Degradable white breathable reflective cover film material and preparation method thereof

Abstract

The invention relates to the technical field of reflective cover film material processing, in particular to a degradable white breathable reflective cover film material and a preparation method thereof.The degradable white breathable reflective cover film material is prepared from, by weight, 40-50 parts of polypropylene, 40-50 parts of biodegradable materials, 1-2 parts of anti-UV master batch and 5-9 parts of reflective color master batch; the biodegradable material is composed of a starch graft polymer, polyhydroxyalkanoate and an iron stearate inclusion according to a weight ratio of (5-10): (2-5): 0.3. Through the biodegradability of the starch grafted polymer and the polyhydroxyalkanoate and the slow-release catalysis effect of the iron stearate wrappage, the degradability and the air permeability of the material are remarkably improved on the basis of ensuring the strength and the light reflection performance of the polypropylene. Meanwhile, the anti-UV master batch effectively prolongs the service life of the material, so that the material can be naturally degraded after meeting the growth cycle requirements of crops, the problem that the traditional polypropylene reflective film is difficult to degrade and recycle is solved, and the anti-UV reflective film has environmental protection property and practicability.

Description

Technical Field

[0001] The present application relates to the technical field of reflective covering film material processing, and more specifically, to a degradable white breathable reflective covering film material and a preparation method thereof. Background Art

[0002] Polypropylene reflective sheeting is made of bright white plastic and effectively reflects sunlight, reflecting the majority of visible light back into the crop canopy, increasing light intensity and photosynthetically active radiation in the lower and middle parts of the crop. Furthermore, polypropylene is inherently weather-resistant, maintaining relatively stable performance in outdoor environments exposed to natural factors such as UV rays, wind and rain. Unlike some common reflective materials, it will not age, discolor, or experience a significant decrease in reflective effectiveness over a short period of time. Its service life typically lasts for several months or even longer, meeting the needs of a single crop growing season.

[0003] However, with the continuous development of agricultural production, the recycling and disposal issues faced by polypropylene reflective sheeting after use have become increasingly prominent. Due to its resistance to natural degradation, if not properly recycled, the polypropylene reflective sheeting remaining in the soil can damage the soil structure, affecting its air and water permeability, and in turn negatively impacting the soil ecosystem and subsequent crop growth. This, to a certain extent, hinders the sustainable development of agriculture. Summary of the Invention

[0004] In order to improve the degradability of polypropylene reflective film, the present application provides a degradable white breathable reflective covering film material and a preparation method thereof.

[0005] In a first aspect, the present application provides a degradable white breathable reflective covering film material, which adopts the following technical solution: A degradable white breathable reflective covering film material is prepared from the following raw materials in parts by weight: 40-50 parts polypropylene 40-50 parts of biodegradable materials 1-2 copies of UV-resistant masterbatch 5-9 parts of reflective masterbatch; The biodegradable material is composed of starch graft polymer, polyhydroxyalkanoate and iron stearate wrapping in a weight ratio of (5-10): (2-5): 0.3; The iron stearate inclusions were prepared according to the following method: Mixing iron stearate and polyethylene glycol, heating in a water bath at 70-80°C, stirring for 1-2 hours after the iron stearate is fully dissolved in the polyethylene glycol, and slowly cooling at room temperature to obtain a solid, which is then placed in a vacuum drying oven to obtain an iron stearate inclusion; The weight ratio of the iron stearate to the polyethylene glycol is 5:(20-30).

[0006] By adopting the above technical solution, the biodegradable material in this application is composed of a starch graft polymer, polyhydroxyalkanoate, and an iron stearate coating. Both the starch graft polymer and the polyhydroxyalkanoate can gradually decompose under the action of microorganisms in the natural environment. The iron stearate coating promotes the entire biodegradation process. These three components work synergistically, allowing the entire reflective covering film material to gradually degrade in the natural environment after its service life, avoiding the problem of long-term residue in the soil and damage to soil structure. This effectively solves the problem of traditional polypropylene reflective film being difficult to recycle and difficult to degrade.

[0007] When iron stearate is coated with polyethylene glycol, it can reduce direct contact with oxygen, thereby reducing the possibility of oxidation during use. This makes the chemical properties of iron stearate in the material more stable and less susceptible to deterioration due to oxidation, thereby extending the service life of the material. In the early stages of the material's use, the iron stearate is tightly coated with polyethylene glycol, making it relatively stable and unlikely to release the iron stearate easily. This ensures the material's performance stability during use and enables it to meet the requirements of use within the crop growth cycle. When the material completes its mission and enters the natural environment, the polyethylene glycol degrades relatively quickly under natural conditions. As the polyethylene glycol gradually degrades, the iron stearate is slowly released. The released iron stearate can act as a catalyst for microbial degradation, promoting the decomposition of biodegradable materials and accelerating the degradation of the entire material, allowing it to better integrate into the cycle of the natural environment.

[0008] At the same time, the addition of biodegradable materials in this application does not completely undermine the advantages of polypropylene, while also giving the material biodegradable properties. The presence of polypropylene ensures sufficient strength and stability during the life cycle of the reflective cover film, while the biodegradable materials provide the possibility of subsequent degradation.

[0009] The starch graft polymer and polyhydroxyalkanoate components in the biodegradable material have a looser molecular structure than polypropylene. When mixed with other components to form a film, they form tiny pores or channels within the reflective cover film. These channels allow air molecules to exchange between the two sides of the film, thus achieving breathability.

[0010] The high reflectivity components in the reflective masterbatch work in conjunction with the optical properties of polypropylene. The high light transmittance and low scattering characteristics of polypropylene enable the active ingredients in the reflective masterbatch to play a better role, reflecting most of the visible light back to the crop canopy, thereby enhancing the reflective effect.

[0011] Anti-UV masterbatch can absorb ultraviolet rays, thereby protecting polypropylene and biodegradable materials from excessive damage by ultraviolet rays, extending the service life of the materials in outdoor environments, and enabling the materials to maintain relatively stable performance while meeting the crop growth cycle.

[0012] Preferably, the molecular weight of the polyethylene glycol is 2000-7000.

[0013] By adopting the above technical solution, the molecular weight of polyethylene glycol is optimized so that it has moderate viscosity and fluidity, can be fully mixed with iron stearate and evenly wrap the iron stearate particles, the iron stearate can be evenly dispersed in the polypropylene matrix, and can form a continuous and stable film on the surface of the iron stearate, so that the iron stearate inclusions can remain stable in the material and are not easily broken or fallen off, thereby extending the service life of the material.

[0014] Preferably, the polypropylene is modified polypropylene, which is prepared by the following method: 1) polypropylene, acrylic acid monomer, and DCP initiator are mixed in a weight ratio of (90-100): (5-10): 0.1, added to a high-speed mixer, and mixed evenly to fully disperse the components to obtain a mixture; 2) adding the mixture into a twin-screw extruder, extruding, and pelletizing to obtain modified polypropylene; The temperature of each zone is set as follows: the temperature of the feeding section is 170-180℃, the temperature of the compression section is 190-200℃, the temperature of the homogenization section is 210-220℃, and the screw speed is 200-300r / min.

[0015] By adopting this technical solution, the original polypropylene, which had poor compatibility with biodegradable materials and exhibited interface defects that affected material performance, was modified by the introduction of acrylic acid monomers. This increased polarity improves compatibility with biodegradable materials such as starch graft polymers and polyhydroxyalkanoates, reduces interface defects, and enhances overall material performance. The modified polypropylene is more compatible with the components of the reflective masterbatch, enabling a more uniform dispersion of the masterbatch within the polypropylene matrix. This uniform dispersion improves the uniformity and stability of the material's reflective properties, ensuring consistent reflective effects across the entire cover film.

[0016] At the same time, the modified polypropylene interacts with biodegradable materials, promoting the overall degradation performance of the reflective film. Furthermore, the modified polypropylene itself may also absorb moisture and microbial activity to a certain extent, thereby accelerating its own degradation, reducing the amount of reflective film remaining in the soil and minimizing damage to the soil ecological environment.

[0017] Preferably, the acrylic acid monomer is prepared from methyl acrylate and hydroxyethyl acrylate in a weight ratio of (6-9):3.

[0018] By employing the above technical solution and optimizing the type and dosage ratio of acrylic acid monomers, the modified polypropylene molecular chains are made more susceptible to water erosion in the natural environment, thereby accelerating the degradation of polypropylene. The combination of methyl acrylate and hydroxyethyl acrylate introduces functional groups with different properties. The hydroxyl groups in hydroxyethyl acrylate enhance the material's hydrophilicity, making the reflective film more susceptible to water absorption in soil environments, thereby accelerating microbial erosion and decomposition. Furthermore, the introduction of acrylic acid monomers disrupts the regularity of the polypropylene molecular chains, reducing the material's crystallinity and accelerating its degradation in the natural environment.

[0019] Furthermore, polypropylene itself is a highly crystalline polymer with relatively poor air permeability. However, grafting with acrylic acid monomers reduces the regularity of the polypropylene molecular chains and lowers their crystallinity, thereby creating more microporous structures and air channels within the material. Furthermore, the hydroxyl groups in hydroxyethyl acrylate have a certain degree of hydrophilicity, which can absorb a certain amount of water, further promoting gas exchange within the material and enhancing the air permeability of the reflective film. This facilitates soil air permeability and moisture regulation during crop growth, creating a more favorable growing environment for crops.

[0020] The introduction of acrylic monomers changes the surface properties of polypropylene, improves the surface roughness and light scattering ability of the material, and enables the reflective film to more effectively reflect various wavelengths of sunlight.

[0021] Preferably, the reflective masterbatch is prepared by the following method: Yttrium-doped zinc oxide, mica powder, barium sulfate and polylactic acid are mixed in a weight ratio of (1-2): (3-5): (6-8): 20, and then added into a twin-screw extruder, extruded, and pelletized to obtain reflective masterbatch.

[0022] By employing this technical solution, yttrium-doped zinc oxide possesses a high refractive index, effectively reflecting light, particularly ultraviolet and visible light, enhancing the reflective brightness of the mulch film. The layered structure of the mica powder creates a specular reflection, allowing light to be regularly reflected to the crop canopy, improving light energy utilization. Barium sulfate further scatters and reflects light, filling gaps in the mica powder's reflections and making the reflected light more uniform. These three factors synergistically enhance the mulch film's reflective properties, increasing light intensity and photosynthetically active radiation in the lower and middle parts of the crop.

[0023] Barium sulfate also has high chemical stability and appropriate porosity, which helps form tiny channels in the reflective film, allowing air and water vapor to exchange through these channels, thereby enhancing the film's breathability. Polylactic acid is a biodegradable material with certain breathability and biodegradability. Its presence in reflective masterbatch not only helps improve the film's breathability but also improves its biodegradability to a certain extent, reducing environmental pollution.

[0024] Preferably, the average particle size of the mica powder is 0.1-0.5 μm.

[0025] Preferably, the average particle size of the barium sulfate is 0.01-0.2 μm.

[0026] Preferably, the average particle size of the yttrium-doped zinc oxide is 30-50 nm.

[0027] By employing the above technical solution, the average particle sizes of mica powder, barium sulfate, and yttrium-doped zinc oxide are optimized, helping to improve the reflective efficiency of the reflective sheeting for visible light, enhancing the brightness and uniformity of the reflected light. The flaky structure of the mica powder enables multiple reflections and scattering of incident light, increasing the light's residence time on the sheeting's surface. The barium sulfate, with its small particle size, high refractive index, and excellent chemical stability, is evenly distributed throughout the sheeting, forming dense reflection points that scatter and reflect light. This ensures excellent reflective effect at various angles, improving the sheeting's uniformity and overall reflective performance. Yttrium-doped zinc oxide has the smallest particle size, a high specific surface area, and excellent UV reflectivity. Its nanometer-scale particle size allows for more uniform distribution throughout the sheeting, forming a dense protective layer that effectively absorbs and reflects UV light. The combined effect of these three ingredients results in multiple reflections and scattering of light from the surfaces of particles of varying particle sizes, enhancing the sheeting's brightness and uniformity.

[0028] At the same time, the particle sizes of the three are different, which can form a tiny pore structure. These gaps can provide channels for the diffusion of gas molecules, allowing air and water vapor to exchange through these channels, thereby enhancing the air permeability of the reflective film.

[0029] Preferably, the UV-resistant masterbatch is prepared by the following method: Polylactic acid, an anti-UV agent and a dispersant are mixed in a weight ratio of (5-6): (0.5-1): (1-2), and then fed into a twin-screw extruder for extrusion and granulation to obtain an anti-UV masterbatch.

[0030] By adopting the above technical solution, polylactic acid is used as a matrix material, providing a carrier for anti-UV agents and other agents, allowing them to be evenly dispersed throughout the reflective sheeting, thereby enhancing the overall performance of the sheeting. The anti-UV agent effectively absorbs and shields ultraviolet rays, preventing photodegradation of the reflective sheeting by ultraviolet rays, thereby extending the service life of the sheeting. The dispersant improves the compatibility and dispersibility of the various components, reducing performance variations caused by component aggregation, and achieving more uniform performance of the reflective sheeting. The lubricant reduces friction between the various components during processing, improving processing fluidity, and enhancing production efficiency and product quality.

[0031] In a second aspect, the present application provides a method for preparing a degradable white breathable reflective covering film material, which adopts the following technical solution: A method for preparing a degradable white breathable reflective covering film material comprises the following steps: Polypropylene, biodegradable materials, anti-UV masterbatch and reflective color masterbatch are mixed, and then extruded and granulated to obtain a degradable white breathable reflective covering film.

[0032] By employing this technical solution, the raw materials are fully dispersed and integrated during the mixing process, ensuring the uniformity and stability of the mulch film. The synergistic effect of polypropylene and biodegradable materials ensures that the mulch film not only has excellent mechanical properties and weather resistance, but also gradually degrades after use, reducing environmental pollution. The addition of anti-UV masterbatch effectively improves the mulch film's UV resistance and aging resistance, extending its service life. The reflective masterbatch imparts excellent reflective properties to the mulch film, increasing light intensity and photosynthetically active radiation in the lower and middle parts of crops. Furthermore, the mulch film produced by this process also has excellent air permeability, which facilitates soil ventilation and moisture regulation.

[0033] In summary, this application has the following beneficial effects: 1. Improve degradability: By adding biodegradable materials (starch grafted polymer, polyhydroxyalkanoate and iron stearate wrapping), the reflective film is more easily decomposed by microorganisms in the natural environment, reducing long-term pollution to the soil and solving the problem that traditional polypropylene reflective film is difficult to degrade.

[0034] 2. Maintain reflective properties: Add reflective masterbatch to the formula to ensure that the cover film can still effectively reflect most light in the visible light range, increase the light intensity and photosynthetic active radiation in the middle and lower parts of the crop, thereby maintaining and improving crop yield and quality.

[0035] 3. Good air permeability: The degradable white breathable reflective covering film has good air permeability, which is beneficial to soil ventilation and moisture regulation. DETAILED DESCRIPTION

[0036] Preparation Example Preparation Example 1 A UV-resistant masterbatch is prepared by the following method: 50 g of polylactic acid, 0.5 g of anti-UV agent (UV-531) and 1 g of dispersant (calcium stearate) were mixed in a weight ratio of 5:0.5:1:2, and then fed into a twin-screw extruder for extrusion and granulation to obtain anti-UV masterbatch.

[0037] Preparation Example 2 A UV-resistant masterbatch is prepared by the following method: Polylactic acid 55g, anti-UV agent 0.8g (UV-2908) and dispersant 1.5g (polyethylene wax) were mixed in a weight ratio of 5.5:0.8:1.5:2, and then fed into a twin-screw extruder for extrusion and granulation to obtain anti-UV masterbatch.

[0038] Preparation Example 3 A UV-resistant masterbatch is prepared by the following method: 60 g of polylactic acid, 1 g of anti-UV agent (UV-328) and 2 g of dispersant (oleic acid amide) were mixed in a weight ratio of 6:1:1:2, and then fed into a twin-screw extruder for extrusion and granulation to obtain anti-UV masterbatch.

[0039] Preparation Example 4 A reflective masterbatch is prepared by the following method: 10 g of yttrium-doped zinc oxide, 30 g of mica powder, 60 g of barium sulfate and 200 g of polylactic acid were mixed in a weight ratio of 1:3:6:20, added into a twin-screw extruder, extruded, and pelletized to obtain a reflective masterbatch.

[0040] The average particle size of mica powder is 0.1 μm.

[0041] The average particle size of barium sulfate is 0.01 μm.

[0042] The average particle size of yttrium-doped zinc oxide is 30 nm.

[0043] Preparation Example 5 A reflective masterbatch is prepared by the following method: 15 g of yttrium-doped zinc oxide, 40 g of mica powder, 70 g of barium sulfate and 200 g of polylactic acid were mixed in a weight ratio of 1.5:5:7:20, added into a twin-screw extruder, extruded, and pelletized to obtain a reflective masterbatch.

[0044] The average particle size of the mica powder is 0.3 μm.

[0045] The average particle size of barium sulfate is 0.1 μm.

[0046] The average particle size of yttrium-doped zinc oxide is 40 nm.

[0047] Preparation Example 6 A reflective masterbatch is prepared by the following method: 20 g of yttrium-doped zinc oxide, 50 g of mica powder, 80 g of barium sulfate and 200 g of polylactic acid were mixed in a weight ratio of 1:5:8:20, added into a twin-screw extruder, extruded, and pelletized to obtain a reflective masterbatch.

[0048] The average particle size of the mica powder is 0.5 μm.

[0049] The average particle size of barium sulfate is 0.2 μm.

[0050] The average particle size of yttrium-doped zinc oxide is 50 nm.

[0051] Preparation Example 7 A reflective masterbatch. The difference between this preparation example and Preparation Example 4 is that no mica powder is added.

[0052] Preparation Example 8 A reflective masterbatch. The difference between this preparation example and Preparation Example 4 is that barium sulfate is not added.

[0053] Preparation Example 9 A reflective masterbatch. The difference between this preparation example and Preparation Example 4 is that the average particle size of the mica powder is 1 μm. Example

[0054] Polypropylene was purchased from Shanghai Yuanye Biotechnology Co., Ltd. under the catalog number S52842.

[0055] Polylactic acid (PLA) was purchased from Guangzhou Yuanda New Materials Co., Ltd., with a purity of 100% and a packaging of 1 kg.

[0056] Starch grafted polycaprolactone copolymer was purchased from Xi'an Ruixi Biotechnology Co., Ltd., model R-22000.

[0057] Example 1 A degradable white breathable reflective covering film material is prepared by the following method: 400 g of polypropylene, 400 g of biodegradable material, 10 g of anti-UV masterbatch (from Preparation Example 1), and 50 g of reflective masterbatch (from Preparation Example 4) were mixed, and then extruded and granulated to obtain a degradable white breathable reflective covering film.

[0058] The biodegradable material is composed of starch graft polymer (starch grafted polycaprolactone copolymer), polyhydroxyalkanoate and iron stearate wrapping in a weight ratio of 5:2:0.3; The iron stearate inclusions were prepared according to the following method: Mix 50 g of iron stearate and 200 g of polyethylene glycol, heat in a water bath, control the temperature at 70°C, and continue stirring for 1 hour after the iron stearate is fully dissolved in the polyethylene glycol. Place the mixture at room temperature and slowly cool to obtain a solid. Place the solid in a vacuum drying oven to obtain an iron stearate inclusion.

[0059] The molecular weight of polyethylene glycol is 2000.

[0060] The difference between Example 2-3 and Example 1 is that the raw material types, amounts and parameters for preparing the degradable white breathable reflective covering film material are different. The specific differences are shown in Table 1: Table 1: Types, amounts and parameters of raw materials for preparing degradable white breathable reflective covering film materials in Examples 1-3 The iron stearate inclusions in Example 2 were prepared according to the following method: Mix 50 g of iron stearate and 250 g of polyethylene glycol, heat in a water bath, control the temperature at 75°C, and continue stirring for 1.5 hours after the iron stearate is fully dissolved in the polyethylene glycol. Place the mixture at room temperature and slowly cool to obtain a solid. Place the solid in a vacuum drying oven to obtain an iron stearate inclusion.

[0061] The molecular weight of polyethylene glycol is 5000.

[0062] The iron stearate inclusions in Example 3 were prepared according to the following method: Mix 50 g of iron stearate and 300 g of polyethylene glycol, heat in a water bath, and control the temperature at 80°C. After the iron stearate is fully dissolved in the polyethylene glycol, continue stirring for 2 hours, place it at room temperature and slowly cool it to obtain a solid. Place the solid in a vacuum drying oven to obtain an iron stearate inclusion.

[0063] The molecular weight of polyethylene glycol is 7000.

[0064] Example 4 A degradable white breathable reflective covering film material. This embodiment differs from Example 1 in that the polypropylene is modified polypropylene, which is prepared by the following method: 1) 450 g of polypropylene, 250 g of acrylic acid monomer, and 0.5 g of DCP initiator were mixed in a weight ratio of 90:5:0.1, added to a high-speed mixer, and mixed evenly to fully disperse the components to obtain a mixture; 2) adding the mixture into a twin-screw extruder, extruding, and pelletizing to obtain modified polypropylene; The temperature of each zone was set as follows: the feeding section temperature was 170°C, the compression section temperature was 190°C, the homogenization section temperature was 210°C, and the screw speed was 200 r / min.

[0065] The acrylic acid monomer is prepared from methyl acrylate and hydroxyethyl acrylate in a weight ratio of 6:3.

[0066] Example 5 A degradable white breathable reflective covering film material. This embodiment differs from Example 1 in that the polypropylene is modified polypropylene, which is prepared by the following method: 1) 500 g of polypropylene, 50 g of acrylic acid monomer, and 0.5 g of DCP initiator were mixed in a weight ratio of 100:10:0.1, added to a high-speed mixer, and mixed evenly to fully disperse the components to obtain a mixture; 2) adding the mixture into a twin-screw extruder, extruding, and pelletizing to obtain modified polypropylene; The temperature of each zone was set as follows: the feeding section temperature was 180°C, the compression section temperature was 200°C, the homogenization section temperature was 220°C, and the screw speed was 300 r / min.

[0067] The acrylic acid monomer is prepared from methyl acrylate and hydroxyethyl acrylate in a weight ratio of 9:3.

[0068] Example 6 A degradable white breathable reflective covering film material. The difference between this embodiment and Example 1 is that the reflective masterbatch comes from Preparation Example 7.

[0069] Example 7 A degradable white breathable reflective covering film material. The difference between this embodiment and Example 1 is that the reflective masterbatch comes from Preparation Example 8.

[0070] Example 8 A degradable white breathable reflective covering film material. The difference between this embodiment and Example 1 is that the reflective masterbatch comes from Preparation Example 9.

[0071] Comparative Example Comparative Example 1 A degradable white breathable reflective covering film material. The difference between this comparative example and Example 1 is that the biodegradable material is a starch graft polymer.

[0072] Comparative Example 2 A degradable white breathable reflective covering film material. The difference between this comparative example and Example 1 is that the iron stearate wrapping is replaced by iron stearate.

[0073] Comparative Example 3 A degradable white breathable reflective covering film material. The difference between this comparative example and Example 1 is that the biodegradable material consists of starch graft polymer and polyhydroxyalkanoate in a weight ratio of 5:2.

[0074] Comparative Example 4 A biodegradable white breathable reflective covering film material. The difference between this comparative example and Example 1 is that the biodegradable material is polylactic acid.

[0075] Comparative Example 5 A degradable white breathable reflective covering film material. The difference between this comparative example and Example 1 is that the reflective masterbatch is replaced by barium sulfate.

[0076] Detection method / test method The degradable white breathable reflective covering film materials prepared in Examples 1-8 and Comparative Examples 1-5 were extruded, cast, stretched, and heat-set to form films, thereby obtaining degradable white breathable reflective covering films with a thickness of 0.1 mm.

[0077] Degradability: According to GB / T 19277.1-2011 standard, the degradation rate of degradable white breathable reflective covering film was tested by composting method.

[0078] Reflectivity: Calibrate the spectrophotometer to the standard setting, then place the degradable white breathable reflective cover film sample to be tested on the spectrophotometer's integrating sphere, ensuring that the sample surface is flat and in close contact with the integrating sphere. The spectrophotometer automatically measures reflectance at 10nm intervals within the wavelength range of 400-1100nm, recording the reflectance value corresponding to each wavelength. Record the average reflectance value for the visible light band of 400-700nm; the average reflectance value for the near-infrared band of 700-1100nm.

[0079] Air permeability: The water vapor permeability of the degradable white breathable reflective covering film was measured at a temperature of 23° C. using a moisture permeability tester sold by MOCON, USA under the trade name Permatran-w3 / 61, in accordance with ASTM 1434-8.

[0080] Durability: Cut the degradable white breathable reflective covering film sample into 10cm×10cm pieces and place them in a UV aging test chamber. Set the test chamber parameters, such as UV intensity of 0.85W / m 2 ±0.02W / m 2 The temperature is 60℃±2℃, the humidity is 50%±5%, and the test period is 600 hours. Observe the changes on the surface, such as whether there is discoloration, cracking, shrinkage, etc., and record them. The experimental data are shown in Table 2: Table 2 Experimental data of Examples 1-8 and Comparative Examples 1-5 It can be seen from the experimental data of Example 1 and Comparative Examples 1-5 that the degradable white breathable reflective covering film in Example 1 is superior to Comparative Examples 1-5 in terms of comprehensive performance such as degradation rate, reflectivity and water vapor permeability, indicating that the biodegradable material formula (a combination of starch grafted polymer, polyhydroxyalkanoate and iron stearate wrapping) and the preparation method of modified polypropylene used in the example can effectively improve the comprehensive performance of the covering film, and can better balance the degradability, reflective performance and air permeability of the covering film to meet the needs of agricultural applications.

[0081] It can be seen from the experimental data of Examples 1 and 4-5 that the use of modified polypropylene significantly improves the degradation rate, reflectivity and water vapor permeability of the degradable white breathable reflective covering film. This shows that the introduction of modified polypropylene can significantly improve the biodegradability of the covering film while maintaining good reflective properties and breathability, making it more environmentally friendly and efficient in agricultural applications.

[0082] The experimental data from Examples 1 and 6-8 demonstrate that the optimal combination of mica powder and barium sulfate in the reflective masterbatch plays a crucial role in improving the reflectivity and air permeability of the degradable white breathable reflective cover film. The absence of either component or the use of mica powder with a larger particle size significantly reduces the reflectivity and air permeability of the cover film, while having a relatively minor impact on the degradation rate.

[0083] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A degradable white breathable reflective covering film material, characterized in that: Prepared from the following raw materials in parts by weight: 40-50 parts polypropylene 40-50 parts of biodegradable materials 1-2 copies of UV-resistant masterbatch 5-9 parts of reflective masterbatch; The biodegradable material is composed of starch graft polymer, polyhydroxyalkanoate and iron stearate wrapping in a weight ratio of (5-10): (2-5): 0.3; The iron stearate inclusions were prepared according to the following method: Mixing iron stearate and polyethylene glycol, heating in a water bath at 70-80°C, stirring for 1-2 hours after the iron stearate is fully dissolved in the polyethylene glycol, and slowly cooling at room temperature to obtain a solid, which is then placed in a vacuum drying oven to obtain an iron stearate inclusion; The weight ratio of the iron stearate to the polyethylene glycol is 5:(20-30).

2. The degradable white breathable reflective covering film material according to claim 1, characterized in that: The molecular weight of the polyethylene glycol is 2000-7000.

3. The degradable white breathable reflective covering film material according to claim 1, characterized in that: The polypropylene is modified polypropylene, which is prepared by the following method: 1) Prepare polypropylene, acrylic acid monomer and DCP initiator in a weight ratio of (90-100): (5-10): 0.1, add to a high-speed mixer, mix evenly, make all components fully dispersed, and obtain a mixture; 2) adding the mixture into a twin-screw extruder, extruding, and pelletizing to obtain modified polypropylene; The temperature of each zone is set as follows: the temperature of the feeding section is 170-180℃, the temperature of the compression section is 190-200℃, the temperature of the homogenization section is 210-220℃, and the screw speed is 200-300r / min.

4. The degradable white breathable reflective covering film material according to claim 3, characterized in that: The acrylic acid monomer is prepared from methyl acrylate and hydroxyethyl acrylate in a weight ratio of (6-9):

3.

5. The degradable white breathable reflective covering film material according to claim 1, characterized in that: The reflective masterbatch is prepared by the following method: Yttrium-doped zinc oxide, mica powder, barium sulfate and polylactic acid are mixed in a weight ratio of (1-2): (3-5): (6-8): 20, and then added into a twin-screw extruder, extruded, and pelletized to obtain a reflective masterbatch.

6. The degradable white breathable reflective covering film material according to claim 5, characterized in that: The average particle size of the mica powder is 0.1-0.5 μm.

7. The degradable white breathable reflective covering film material according to claim 5, characterized in that: The average particle size of the barium sulfate is 0.01-0.2 μm.

8. The degradable white breathable reflective covering film material according to claim 5, characterized in that: The yttrium-doped zinc oxide has a thickness of 30-50 nm.

9. The degradable white breathable reflective covering film material according to claim 1, characterized in that: The anti-UV masterbatch is prepared by the following method: Polylactic acid, anti-UV agent and dispersant are mixed in a weight ratio of (5-6): (0.5-1): (1-2), and then fed into a twin-screw extruder for extrusion and granulation to obtain anti-UV masterbatch.

10. A method for preparing the degradable white breathable reflective covering film material according to any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: Polypropylene, biodegradable materials, anti-UV masterbatch and reflective color masterbatch are mixed, and then extruded and granulated to obtain a degradable white breathable reflective covering film.

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