Anti-ultraviolet PBAT (poly (butylene adipate-co-terephthalate)) composite degradable agricultural mulching film

Abstract

The utility model relates to the field of agricultural mulching films, mainly aims to solve the problem that the existing PBAT agricultural mulching film is insufficient in ultraviolet shielding effect, and provides an anti-ultraviolet PBAT composite degradable agricultural mulching film which is characterized by comprising a front packaging layer 1 serving as an illuminated surface, an ultraviolet shielding layer 2 and a back packaging layer 3 serving as a soil contact surface which are sequentially stacked, the ultraviolet shielding layer 2 comprises a structural body formed by compounding PBAT and a nanoscale ultraviolet shielding material, the nanoscale ultraviolet shielding material is of a micro-nano composite structure formed by uniformly mixing a nano sheet layer and a micron sheet layer in the ultraviolet shielding layer 2, and the nanoscale ultraviolet shielding material is arranged in a PBAT matrix in an oriented mode to form a brick mud structure. The PBAT degradable composite mulching film can effectively ensure visible light transmission and excellent mechanical properties, can reduce aging and degradation of the mulching film caused by ultraviolet radiation, and can be expected to be used in the agricultural field, especially in the agricultural field especially needing anti-ultraviolet shielding.

Description

Technical Field

[0001] This utility model relates to the field of agricultural mulch film, and in particular to a UV-resistant PBAT composite biodegradable agricultural mulch film. Background Technology

[0002] Polybutylene adipate / terephthalate (PBAT) is a thermoplastic biodegradable plastic, a copolymer of butylene adipate and butylene terephthalate. It is biodegradable, capable of being broken down by microorganisms into water, carbon dioxide, and organic matter in the natural environment, reducing environmental pollution. PBAT has excellent processing properties, making it suitable for manufacturing packaging materials, consumer goods, medical devices, and agricultural mulch films, among other applications, and has significant environmental and economic implications. Traditional agricultural mulch films are typically made of plastics such as polyethylene, but these films may cause environmental problems after use, such as difficulty in degradation and impacts on soil ecosystems. Agricultural mulch films based on PBAT can effectively control soil moisture, temperature, and weed growth, while PBAT's excellent biodegradability allows it to be broken down by microorganisms into harmless substances after use, without long-term impacts on soil and the environment, thereby improving crop yield and quality. However, PBAT itself has the disadvantage of insufficient ultraviolet shielding effect, which causes PBAT agricultural mulch film to degrade and age under ultraviolet radiation, affecting the service life and function of agricultural mulch film, and to some extent hindering the widespread application of PBAT in the field of mulch film.

[0003] Currently, the main strategy for improving the UV shielding of PBAT mulch films is to add UV absorbers to the PBAT granules. UV absorbers are broadly classified into two categories: organic and inorganic. Common organic absorbers include phenols and styrene, but these organic absorbers themselves possess a certain degree of toxicity, causing damage to organisms and the natural environment both during use and after disposal. Inorganic absorbers are inorganic substances such as metal oxides and metal complexes, with typical examples including zinc oxide and titanium dioxide. However, inorganic UV absorbers have drawbacks such as narrow absorption wavelengths, limited photostability, and poor dispersion, which can introduce mechanical defects when added to PBAT mulch films. Furthermore, some UV absorbers possess a certain color, which, when added to PBAT mulch films, reduces the film's visible light transmittance, affecting the film's color and performance.

[0004] In conclusion, how to achieve superior UV shielding effect of PBAT agricultural mulch film through structural improvements without affecting its mechanical strength, biodegradability, and visible light transmittance is a problem that urgently needs to be solved in this field. Utility Model Content

[0005] This invention addresses the problem of insufficient UV shielding effect of current PBAT-based agricultural mulch films by designing and providing a UV-resistant PBAT composite biodegradable agricultural mulch film. It not only maintains the light transmittance and mechanical properties of the mulch film itself, but also has excellent UV shielding effect, effectively blocking ultraviolet rays, delaying the aging and degradation of the mulch film, and extending its service life.

[0006] The solution adopted in this invention is a UV-resistant PBAT composite biodegradable agricultural mulch film, which comprises a front sealing layer (sun-receiving surface), a UV-shielding layer, and a back sealing layer (soil-contacting surface) stacked sequentially. The front and back sealing layers are composed of a single PBAT film, while the UV-shielding layer is composed of PBAT and nano-scale UV-shielding materials in a specific ratio. Because the nano-scale UV-shielding materials are uniformly composited and oriented within the PBAT matrix to form a brick-and-mortar structure, this layer exhibits excellent UV-shielding performance. Combined with the front and back sealing layers, while effectively ensuring visible light transmission and excellent mechanical properties, the mulch film's superior UV-shielding effect can significantly improve the efficiency and quality of agricultural production.

[0007] The brick-and-mortar structure refers to a structure in which nanoscale ultraviolet shielding materials, such as mica sheets, are equivalent to the "bricks" in a building wall, while the PBAT matrix is ​​the "mortar." The mica sheets are arranged in an orderly orientation within the thin film matrix to construct the "brick-and-mortar" structure.

[0008] Preferably, the crystallization temperature of the above-mentioned PBAT is 105-110℃, the melting point is 110-140℃, and the density is 1.0-1.3g / ml. -1 The crystallinity is 30%-35%.

[0009] Preferably, the diameter of the micron-scale sheets is 20-50 μm, the diameter of the nano-scale sheets is 100-500 nm, and the composite ratio of the nano-scale sheets and the micron-scale sheets is 3:7 to 7:3, preferably 1:1.

[0010] The nanoscale ultraviolet shielding material accounts for 2%-10% of the total mass fraction of the ultraviolet shielding layer.

[0011] During the formation of the ultraviolet shielding layer, micron- and nano-sheets are uniformly distributed in the PBAT film through shear force oriented deformation assembly technology, and are oriented and arranged in the PBAT film matrix under the orientation force of the film shear force deformation assembly technology.

[0012] Preferably, the nanoscale ultraviolet shielding material is selected from phlogopite sheets with a micro-nano composite structure.

[0013] Preferably, the thickness of the front encapsulation layer is 10-20 μm, the thickness of the ultraviolet shielding layer is 5-10 μm, and the thickness of the back encapsulation layer is 10-20 μm.

[0014] Preferably, the front encapsulation layer, the ultraviolet shielding layer and the back encapsulation layer are prepared by a layer-by-layer assembly process, and then hot-pressed at 80-95°C.

[0015] Preferably, the front encapsulation layer, the ultraviolet shielding layer, and the back encapsulation layer are directly stacked together.

[0016] Preferably, the front encapsulation layer 1, the ultraviolet shielding layer 2, and the back encapsulation layer 3 can be directly laminated using a thermoforming process. In this assembly method, no adhesive layer is required between the layers, which helps save on manufacturing costs and reduces environmental pollution caused by the volatilization of VOC components in the adhesive.

[0017] The beneficial effects of this invention are as follows: Compared to ordinary PBAT agricultural mulch films on the market, this invention possesses superior biodegradability, heat retention and moisture retention, processability, and flexibility, while also exhibiting excellent ultraviolet (UV) shielding performance. Under intense outdoor sunlight and UV radiation, the oriented micro-nano composite mica sheet structure in the PBAT agricultural mulch film causes multiple reflections and scatterings of UV rays on the mica sheet surface, resulting in multiple attenuations of UV radiation and effectively reducing its penetration depth. Furthermore, the synergistic effects of charge transfer and size effect on the mica surface contribute to the film's excellent UV shielding effect. In summary, this PBAT biodegradable composite mulch film effectively ensures visible light transmittance and excellent mechanical properties while reducing aging and degradation caused by UV radiation, thereby reducing the frequency of mulch film replacement and saving on agricultural film costs. Secondly, the film's excellent UV shielding effectively protects crop roots from UV radiation damage, promotes crop growth and development, improves crop yield and growth quality, and significantly enhances agricultural production efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the cross-sectional structure of a UV-resistant PBAT composite biodegradable agricultural mulch film according to the present invention, wherein 1 is the front sealing layer; 2 is the UV shielding layer; and 3 is the back sealing layer.

[0019] Figure 2 The results show the reflectance of the thin film samples prepared according to Example 1 and Comparative Example 1 in the ultraviolet band.

[0020] Figure 3This is a cross-sectional image of the PBAT thin film prepared according to Example 1 using a scanning electron microscope.

[0021] Figure 4 Cross-sectional images of the sample prepared for comparison example 1 using a scanning electron microscope. Detailed Implementation Plan

[0022] To provide a more detailed and intuitive understanding of this utility model, the following description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the utility model. It should be emphasized that the following description only illustrates preferred embodiments of the utility model and is not intended to limit the utility model. Any simple modifications to the utility model fall within the protection scope of this utility model.

[0023] As Example 1, the preparation was as follows: Figure 1 The image shows a UV-resistant PBAT composite biodegradable agricultural mulch film. It includes a front sealing layer 1, a UV-shielding layer 2, and a back sealing layer 3. The front and back sealing layers are composed of a single PBAT film. PBAT has a crystallization temperature of 105-110℃, a melting point of 110-140℃, and a density of 1.0-1.3 g / ml. -1 The crystallinity is 30%-35%. The ultraviolet shielding layer is composed of PBAT and nano-scale ultraviolet shielding material in a certain proportion. The aforementioned nano-scale ultraviolet shielding material adopts micro-nano composite phlogopite sheets, with the diameter of the micron sheets being 20-50 μm and the diameter of the nanosheets being 100-500 nm. The composite ratio of nanosheets to micron sheets is 1:1, and the micro-nano composite phlogopite sheets account for 2%-10% of the total mass fraction of the ultraviolet shielding layer. The micro- and nanosheets are uniformly distributed in the PBAT film through a shear deformation assembly method. Due to the orientation and uniform composite of the nano-scale ultraviolet shielding material in the PBAT matrix, this layer has excellent ultraviolet shielding effect. Combined with the front and back encapsulation layers, the overall thickness of the front encapsulation layer is 10-20 μm, the ultraviolet shielding layer is 5-10 μm, and the back encapsulation layer is 10-20 μm. The three are prepared by a layer-by-layer assembly process, and then hot-pressed at 80-95℃.

[0024] As a comparative example 1, unlike Example 1, the ultraviolet shielding layer 2 was not assembled by shear force deformation during preparation, but was formed by natural drying without applying any external force.

[0025] Figure 2Thin film samples were prepared for Example 1 and Comparative Example 1, and reflectance curves were obtained by measuring the reflectance using a UV-Vis-NIR spectrophotometer (Shimadzu Corporation, Solid 3700 DUV). The curves show that the PBAT composite film, after orientation and uniform composite, exhibits higher reflectance in the UV band, demonstrating superior UV shielding capability compared to the film in Comparative Example 1.

[0026] Figure 3 This is a cross-sectional image obtained by scanning electron microscopy (GeminiSEM 500 Schottky field emission scanning electron microscope, 3 kV accelerating voltage) of the PBAT thin film prepared in Example 1. It can be seen that the sheets are oriented and arranged in the PBAT thin film substrate, forming a "brick-and-mortar" structure, which enhances the ultraviolet shielding performance.

[0027] Figure 4 The image shown is a cross-sectional image obtained using a scanning electron microscope (GeminiSEM 500 Schottky field emission scanning electron microscope, 3 kV accelerating voltage) on the sample prepared in Comparative Example 1. It can be seen that the mica sheets are randomly arranged in the PBAT film, failing to exhibit an ordered "brick-and-mortar" structural characteristic.

[0028] This utility model relates to a UV-resistant PBAT composite biodegradable agricultural mulch film. This PBAT biodegradable composite agricultural mulch film effectively ensures visible light transmittance and excellent mechanical and processability properties, while also possessing excellent UV shielding performance. It effectively reduces the penetration depth of ultraviolet rays, resulting in a better UV shielding effect, meeting the UV shielding requirements of agricultural mulch films, and improving crop yield and agricultural production efficiency.

Claims

1. A UV-resistant PBAT composite biodegradable agricultural mulch film, characterized in that: It includes a front encapsulation layer (1) that serves as the light-receiving surface, an ultraviolet shielding layer (2), and a back encapsulation layer (3) that serves as the soil contact surface, which are stacked in sequence. The phlogopite in the ultraviolet shielding layer (2) has a micro-nano composite structure in which nanosheets and microsheets are uniformly combined. The phlogopite is oriented and arranged in the PBAT matrix of the ultraviolet shielding layer (2) to form a brick-and-mortar structure. The diameter of the microsheets is 20-50 μm, and the diameter of the nanosheets is 100-500 nm.

2. The UV-resistant PBAT composite biodegradable agricultural mulch film according to claim 1, characterized in that: The thickness of the front encapsulation layer (1) is 10-20 μm, the thickness of the ultraviolet shielding layer (2) is 5-10 μm, and the thickness of the back encapsulation layer (3) is 10-20 μm.

3. The UV-resistant PBAT composite biodegradable agricultural mulch film according to claim 1, characterized in that: The front encapsulation layer (1), the ultraviolet shielding layer (2), and the back encapsulation layer (3) are directly stacked together.

4. The UV-resistant PBAT composite biodegradable agricultural mulch film according to claim 3, characterized in that: There is no adhesive layer between the front encapsulation layer (1), the ultraviolet shielding layer (2), and the back encapsulation layer (3).

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