PBAT degradable agricultural mulching film with fertilizer controlled release function

Abstract

The utility model relates to the field of agricultural plastic mulching films, and provides a PBAT degradable agricultural plastic mulching film with a fertilizer controlled release function mainly aiming at the problems of serious pollution and low fertilizer utilization rate of the traditional agricultural plastic mulching film at present. The mulching film comprises a PBAT supporting layer and is characterized in that the mulching film further comprises a fertilizer controlled-release layer stacked on the PBAT supporting layer, the fertilizer controlled-release layer comprises a structural body formed by compounding cellulose nanofibers and urea particles, the cellulose nanofibers form a continuous three-dimensional network in the fertilizer controlled-release layer, the urea particles are dispersed in the three-dimensional network, and the structural body is formed by compounding the cellulose nanofibers and the urea particles. The diameter distribution range of the cellulose nanofibers is 10-60 nm, and the length-diameter ratio distribution range is 10-200. Due to the existence of the controlled release layer with the specific composite layer structure, the fertilizer controlled release layer can gradually release urea into soil in the degradation process, the purpose of slow controlled release of the fertilizer is achieved, and meanwhile multiple functions of heat preservation, moisture preservation and the like are effectively provided for crops.

Description

Technical Field

[0001] This utility model relates to the field of agricultural mulch film, and in particular to a PBAT biodegradable agricultural mulch film with fertilizer controlled release function. Background Technology

[0002] Polybutylene adipate / terephthalate (PBAT) is a thermoplastic biodegradable plastic, a copolymer of butylene adipate and butylene terephthalate. This material exhibits excellent biodegradability, capable of being broken down by microorganisms in the natural environment into water, carbon dioxide, and organic matter, thus reducing environmental pollution. PBAT and its derivative composites are commonly used to manufacture biodegradable plastic products, such as packaging materials, agricultural films, household goods, and medical devices. Furthermore, PBAT possesses good plasticity and processing properties, enabling it to meet the production needs of various specifications of mulch films, effectively providing crops with multiple functions such as heat preservation, moisture retention, and weed control. Compared to traditional agricultural mulch films, PBAT agricultural mulch films can naturally degrade into carbon dioxide and water within a certain period after use, without causing persistent soil pollution. This helps maintain soil ecological balance and long-term fertility, reducing environmental pollution and achieving a good balance between agricultural production and environmental protection.

[0003] Currently, fertilization methods in crop management encompass various strategies such as surface application, application combined with irrigation, and deep burial. However, the release pattern and rate of traditional fast-acting chemical fertilizers in the soil are not easily controlled with precision. Due to their rapid dissolution characteristics, these fertilizers are easily washed away by rainwater or applied through irrigation systems, leading to serious nutrient loss. This not only results in a significant waste of agricultural resources but may also pose a risk of groundwater and soil pollution. Furthermore, traditional fertilization methods often tend to apply large doses of fast-acting fertilizer at once, which fails to accurately match the dynamic changes in nutrient requirements at different growth stages. Initially, there may be an oversupply of nutrients, but as the crop grows and develops, there may be a shortage of nutrients later on, thus reducing the effective utilization rate of fertilizer nutrients and hindering the continuous optimization of crop yield and quality.

[0004] Therefore, improving fertilization techniques and strategies to ensure the timely and necessary release of nutrients has become an urgent need for efficient and environmentally friendly production in modern agriculture. PBAT mulch film can be structurally designed and combined with a fertilizer control-release layer to create a new type of PBAT-based biodegradable mulch film material with control-release functionality. The control-release layer of this type of mulch film can effectively regulate the fertilizer release rate, thereby improving fertilizer utilization efficiency and reducing potential pollution to the ecological environment. Therefore, how to achieve uniform and continuous controlled release of fertilizer during the degradation process of PBAT agricultural mulch film 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 problems of severe pollution and low fertilizer utilization rate of traditional agricultural mulch films by providing a PBAT biodegradable agricultural mulch film with controlled fertilizer release function. It not only maintains the visible light transmittance and mechanical properties of the mulch film itself, but also has excellent controlled fertilizer release function to achieve slow release of fertilizer and gradually release nutrients according to the needs of crop growth, which helps to avoid excessive fertilizer application.

[0006] To solve the above-mentioned technical problems, the solution adopted by this utility model is: to provide a PBAT biodegradable agricultural mulch film with fertilizer controlled release function, the mulch film including a PBAT support layer (1), characterized in that: the mulch film also includes a fertilizer controlled release layer (2) stacked on the PBAT support layer (1), the fertilizer controlled release layer (2) including a structure composed of cellulose nanofibers and urea particles, the cellulose nanofibers forming a continuous three-dimensional network in the fertilizer controlled release layer (2), the urea particles being dispersed in the three-dimensional network, the diameter distribution range of the cellulose nanofibers being 10-60 nm, and the aspect ratio distribution range being 10-200.

[0007] In this invention, the support layer is made of a single PBAT film material, ensuring excellent mechanical properties and good visible light transmittance, meeting the basic requirements of modern agriculture for mulch films. The fertilizer controlled-release layer is composed of cellulose nanofibers and urea in a specific ratio.

[0008] Preferably, there is no adhesive layer between the PBAT support layer and the fertilizer controlled-release layer.

[0009] Preferably, the PBAT support layer and the fertilizer controlled-release layer are prepared by a layer-by-layer assembly process.

[0010] Preferably, the PBAT support layer is first corona treated to enhance its surface affinity and adhesion. Next, a pre-prepared mixture of urea and cellulose nanofibers is uniformly deposited onto the PBAT support layer using a precision pumping system and an atomization spraying process, ensuring the fertilizer components are released evenly and slowly during the film's degradation. While maintaining the original optical and mechanical advantages of the PBAT film, a simple and efficient cellulose slurry spraying process integrates a controlled-release fertilizer layer, effectively improving fertilizer utilization and significantly enhancing the efficiency and quality of agricultural production.

[0011] Corona treatment of the PBAT support layer can improve its surface structure. The surface of the PBAT film before corona treatment is hydrophobic, but the main body of the controlled-release layer to be sprayed on it is composed of hydrophilic cellulose nanofibers, which are relatively hydrophilic. Therefore, the PBAT support layer preferably needs to be corona treated to achieve better bonding between the two layers.

[0012] 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 between 30% and 35%.

[0013] Preferably, the cellulose nanofibers described above have a solid content of 0.5-1%, a diameter distribution ranging from 10 to 60 nm, an aspect ratio distribution ranging from 10 to 200, a crystallinity distribution ranging from 75 to 90%, and a surface charge distribution ranging from -50 to -10 mV. Crystallinity and surface charge further define the cellulose nanofibers in the slow-release layer. Cellulose nanofibers possessing these characteristics have a larger specific surface area, better intrinsic mechanical properties and thermal stability, and stronger interactions with the slow-release fertilizer, thus better enabling the slow-release mulch film to exert its effects and provide protection in the soil.

[0014] Preferably, the urea particle size is 0.85-2.80 mm, and the urea accounts for 20%-40% of the total mass fraction of the controlled-release fertilizer layer; the urea is thoroughly and uniformly mixed with cellulose nanofibers so that the urea is evenly distributed in the cellulose nanofiber film matrix.

[0015] In the controlled-release layer of this invention, the uniformity of urea dispersion in the cellulose film affects the material's effect in actual slow release. There is no special limitation on the thickness; the thickness of the layer is mainly controlled according to the actual application scenario and the type of crop. However, generally speaking, the greater the thickness, the greater the slow-release amount of fertilizer.

[0016] Preferably, the thickness of the PBAT support layer is 15-25 μm, and the thickness of the fertilizer controlled-release layer is 5-10 μm.

[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 preservation and moisture retention properties, processability, and flexibility, while also exhibiting excellent fertilizer controlled-release function. With changes in time and environmental conditions, the PBAT mulch film begins to hydrolyze and undergo microbial degradation. When the composite mulch film degrades to a certain extent, cellulose gradually degrades into polysaccharide fragments and further transforms into glucose. The fertilizer controlled-release layer slowly degrades, and the urea fertilizer in the film is gradually released into the soil. At this point, soil microorganisms can fully utilize these nutrients, and crops can also fully absorb and utilize these nutrients, promoting their healthy growth. PBAT agricultural mulch films with fertilizer controlled-release function not only provide crops with effective heat preservation, moisture retention, and weed prevention, but also integrate fertilizer controlled-release function, which can improve fertilizer utilization, promote crop growth and development, increase crop yield and growth quality, and significantly improve agricultural production efficiency. Attached Figure Description

[0018] Figure 1 A schematic diagram of the cross-sectional structure of a PBAT biodegradable agricultural mulch film with controlled fertilizer release function, wherein 1 is the PBAT support layer; 2 is the controlled fertilizer release layer. Detailed Implementation Plan

[0019] 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.

[0020] like Figure 1 As shown, a PBAT biodegradable agricultural mulch film with controlled fertilizer release function includes a PBAT support layer 1 and a fertilizer controlled release layer 2. The support layer is 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. -1The crystallinity is 30%-35%. The fertilizer controlled-release layer is composed of cellulose nanofibers and urea in a certain proportion. The urea particle size is 0.85-2.80 mm, and the urea accounts for 20%-40% of the total mass fraction of the fertilizer controlled-release layer. Urea and cellulose nanofibers are thoroughly and uniformly mixed to ensure that the urea is evenly distributed in the cellulose nanofiber matrix. The PBAT support layer is subjected to corona treatment to enhance the affinity and adhesion of the support layer surface. The pre-prepared urea and cellulose nanofiber mixture is uniformly deposited on the surface of the treated PBAT support layer using an atomization spraying process. Due to the uniform composite of urea and cellulose nanofibers, the fertilizer controlled-release layer can gradually release urea into the soil during the degradation process, achieving the purpose of slow-release fertilizer. The overall thickness of the PBAT support layer is 15-25 μm, and the thickness of the fertilizer controlled-release layer is 5-10 μm.

[0021] This utility model relates to a PBAT biodegradable agricultural mulch film with controlled fertilizer release function. This PBAT biodegradable agricultural mulch film effectively ensures visible light transmittance, excellent mechanical properties, and processability, while also possessing a controlled fertilizer release function. This allows the PBAT film to improve crop yield and agricultural production efficiency during the degradation process.

Claims

1. A PBAT biodegradable agricultural mulch film with controlled fertilizer release function, the mulch film comprising a PBAT support layer (1), wherein PBAT refers to polybutylene adipate / terephthalate, characterized in that: The mulch film also includes a fertilizer controlled-release layer (2) stacked on the PBAT support layer (1). The fertilizer controlled-release layer (2) has a continuous three-dimensional network of cellulose nanofibers and urea particles uniformly dispersed in the three-dimensional network. The diameter of the cellulose nanofibers is distributed in the range of 10-60 nm and the aspect ratio is distributed in the range of 10-200. The particle size of the urea particles is 0.85-2.80 mm, and the thickness of the fertilizer controlled-release layer (2) is 5-10 μm.

2. The PBAT biodegradable agricultural mulch film with fertilizer controlled-release function according to claim 1, characterized in that: The above The thickness of the PBAT support layer (1) is 10-20 μm.

3. The PBAT biodegradable agricultural mulch film with fertilizer controlled-release function according to claim 1, characterized in that: There is no adhesive layer between the PBAT support layer (1) and the fertilizer controlled-release layer (2).

4. The PBAT biodegradable agricultural mulch film with fertilizer controlled-release function according to claim 1, characterized in that: The fertilizer controlled-release layer (2) completely covers the PBAT support layer (1).

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