Controllable bio-based degradable mulching film for rice and preparation method thereof

Abstract

The application belongs to the field of polymer films. The application relates to controllable bio-based degradable mulching film for rice and a preparation method thereof. The material comprises the following raw materials in parts by weight: PBAT resin 70-90 parts; functionalized bamboo fiber 5.0-10.0 parts; modified filler 5-20 parts; black master batch 3.0-5.0 parts; light stabilizer 0.2-0.3 parts; antioxidant 0.2-0.5 parts; lubricant 0.1-0.2 parts; hydrolysis inhibitor 0.5-1.0 parts; wherein the functionalized bamboo fiber comprises a bamboo fiber matrix and a metal-organic ligand functional layer-coupling functional layer loaded on the surface and / or pores thereof; the above raw materials are blended and blown into films to effectively solve the problem that the existing mulching film has controllable degradation and high-efficiency weeding (under the premise of reducing or not using herbicides) at the same time, and effectively promote the construction of ecological agriculture.

Description

Technical Field

[0001] This invention relates to a controllable bio-based biodegradable weed control film for rice and its preparation method. This invention belongs to the field of biodegradable polymer films. Background Technology

[0002] Mulching in rice cultivation serves several purposes, including heat preservation, moisture retention, weed control, and improvement of the field microclimate. Black mulch, in particular, with its strong shading properties, significantly inhibits weed germination and growth, reducing competition for water, nutrients, and light. This is crucial for improving early-stage rice seedling quality and plant uniformity. Especially in direct-seeded rice or some machine-transplanted rice cultivation, when rice seedlings are small and the canopy has not yet closed, abundant weed growth can easily compete with rice for light and nutrients, thus affecting tillering, growth vigor, and final yield. Therefore, black biodegradable mulch has high application value in rice cultivation, effectively reducing or eliminating the need for herbicides and promoting ecological agriculture.

[0003] Currently, PBAT has become one of the main resins for biodegradable agricultural mulch films due to its good flexibility, processability, and biodegradability. However, existing PBAT mulch films generally suffer from insufficient controllability of degradation in rice applications: on the one hand, some films crack too early in the early stages of service, leading to reduced shading and weed control effects, allowing weeds to regrow and compete with rice for nutrients and light, thus affecting normal rice growth and yield; on the other hand, some films degrade too late, leaving a significant amount of film residue after rice harvest, which is detrimental to subsequent cultivation and field environmental management. In particular, rice planting systems vary, with different crops per year (two or three), and the required service time of the mulch film differs for different growth cycles, making it difficult for existing PBAT mulch films to achieve graded control for different cultivation cycles.

[0004] To address the aforementioned issues, existing technologies typically adjust the mechanical properties and degradation behavior of mulch films by adding light stabilizers, anti-hydrolysis agents, inorganic fillers, fibers, or changing the PBAT resin grade. For example, adding light stabilizers and anti-hydrolysis agents can delay early aging, adding fillers can improve mechanical properties and reduce cost, and introducing fibers or degradation-promoting components can accelerate later degradation. However, these methods often have limitations: relying solely on light stabilizers and anti-hydrolysis agents, while extending early service life, can easily delay the initiation of later degradation; simply adding fillers or fibers, while improving some properties, often results in poor interfacial compatibility, decreased mechanical properties, or insufficient stability during blown film processing; and directly adding degradation-promoting components can easily lead to premature early degradation, making it difficult to balance service life stability with rapid later degradation.

[0005] For rice mulch, the mulch does not necessarily need to remain intact throughout the entire growth period; rather, it needs to be matched to the rice's canopy shading stage. Once the rice plants have grown tall and the canopy is closed, even if weeds gain some growing space after the mulch cracks, they will be unable to continue growing vigorously due to the shading effect of the rice canopy. Therefore, at this stage, the impact of mulch cracking on weed control and yield is relatively small. Based on this, different mulch cracking times are suitable for different rice growth stages: for example, for rice with a growth period of about 90 days, mulch cracking at about 60 days is sufficient to meet the early weed control needs; for rice with a growth period of about 120 days, cracking at about 90 days is suitable; and for rice with a growth period of about 180 days, cracking at about 120 days is more appropriate. Therefore, developing a black PBAT biodegradable mulch that can achieve graded cracking control at 60 days, 90 days, and 120 days for different rice growth stages has significant practical application value. Summary of the Invention

[0006] The purpose of this invention is to address the problem of poor controllability of PBAT mulch film in rice cultivation, which affects rice growth. This invention provides a method for preparing a controllable bio-based degradable weed control mulch film for rice. Through formulation design, PBAT is used as the main resin, and two types of PBAT resins with different physical properties are compounded. Pretreated bamboo fiber is used as a carrier, and a metal-organic ligand functional layer and a reactive interface layer are constructed on its surface and / or in its internal pores. Combined with blown film technology, a controllable bio-based degradable weed control mulch film for rice is prepared. This mulch film not only solves the problem of controllable degradation but also has a highly efficient weed control function (reducing or eliminating the use of herbicides), effectively promoting the construction of ecological agriculture. The technical solution adopted by this invention to solve its technical problem is: This invention provides a controllable bio-based degradable weed control film for rice, comprising the following raw materials in parts by weight: 70-90 parts of PBAT resin; Functionalized bamboo fiber 5.0-10.0 parts; 5-20 parts of modified filler; 3.0-5.0 parts of black masterbatch; Light stabilizer 0.2-0.3 parts; Antioxidant 0.2-0.5 parts; Lubricant 0.1-0.2 parts; Anti-hydrolysis agent 0.5-1.0 parts; The functionalized bamboo fiber includes a bamboo fiber matrix and a metal-organic ligand functional layer-coupling functional layer loaded on its surface and / or in its pores.

[0007] Furthermore, The functionalized bamboo fiber includes the following preparation steps: S11, bamboo fiber pretreatment, i.e. Bamboo fibers are subjected to alkali washing, dried after washing, and then crushed or chopped to obtain pretreated bamboo fibers. S12, metal ion adsorption, i.e. Add the S11 product to the metal ion solution to allow the metal ions to be adsorbed on the fiber surface and / or in the internal pores. S13, organic ligand assembly, i.e. The S12 product is transferred into an organic ligand solution, which allows the organic ligand to undergo in-situ complexation with the metal ions adsorbed on the fiber surface, thereby forming a metal-organic ligand functional layer on the surface and / or in the internal pores of the bamboo fiber. S14, Construction of reactive interface layer, i.e. The S13 product is contacted with an epoxy-containing surface treatment agent to introduce a reactive interface layer on its surface; after post-treatment, functionalized bamboo fiber, i.e., the target product, is obtained.

[0008] Furthermore, The metal ion is manganese, copper, or iron; and The organic ligand is tartaric acid, citric acid, or malic acid.

[0009] Furthermore, The PBAT resin is a first PBAT resin and a second PBAT resin in a mass ratio of (0.2-0.8):(0.8-0.2). The first PBAT resin has a melt flow rate of 3-5 g / 10 min and a terminal carboxyl group value of 15-25 mol / t; and The melt flow rate of the second PBAT resin is 3-5 g / 10 min, and the terminal carboxyl group value is 7-15 mol / t.

[0010] Furthermore, The modified filler includes one or more of the following: modified non-grain biomass filler, modified calcium carbonate, or modified talc.

[0011] Furthermore, The modified filler is a hydrophobically modified filler with a particle size of 2000-5000 mesh.

[0012] Furthermore, The black masterbatch is obtained by mixing carbon black and PBAT in a weight ratio of 1:2 and then extruding.

[0013] Furthermore, The light stabilizer is a polymeric hindered amine light stabilizer.

[0014] Another object of the present invention is to provide a method for preparing a controllable bio-based degradable weed control film for rice, comprising the following steps: S21, raw material pretreatment, i.e. PBAT resin, functionalized bamboo fiber, filler, and black masterbatch were pretreated separately. S22, Mixing, i.e. Add the ingredients according to the formula to a mixer and mix for 5-20 minutes to obtain a mixture; and S23, extrusion blown film, i.e. The mixture is directly fed into a blown film extruder for melt plasticizing and blown film forming to obtain a controllable bio-based biodegradable weed control film for rice.

[0015] The beneficial effects of this invention are: (1) This invention provides a controllable bio-based degradable weed control film for rice, with self-made functionalized bamboo fiber added to the formula. First, the metal ions loaded on it have a catalytic degradation regulating effect, which can effectively regulate the degradation time of the film; second, its coupling functional layer can act as a compatibilizer to promote interfacial reaction and improve phase compatibility; third, bamboo fiber can improve the mechanical properties of the film and has a reinforcing effect; fourth, bamboo fiber, as a biomass material, has excellent degradation performance.

[0016] (2) This invention provides a controllable bio-based degradable weed control film for rice. Through formulation design, the degradation time of the film can be further synergistically controlled by PBAT resin with different physical properties and different types and amounts of modified fillers in the formulation.

[0017] (3) This invention provides a controllable bio-based degradable weed control film for rice. Through formulation design, by adding hindered amine light stabilizers, it can maintain long-term light stability while avoiding light competition with functionalized bamboo fiber metal ions after the film cracks, thereby further improving the degradation time control effect.

[0018] In summary, this invention provides a controllable bio-based degradable weed control film for rice. Through reasonable formulation design, the degradation time of the PBAT black film is effectively improved by the synergistic effect of self-made functionalized bamboo fiber, PBAT with different physical properties, and different modified fillers in the base of the black film, which has broad application prospects. Detailed Implementation

[0019] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0020] The purpose of this invention is to develop a controllable bio-based degradable weed control film for rice cultivation, addressing the problem of poor controllability in the degradation of existing PBAT-based black mulch films during rice planting, which negatively impacts rice growth. The design concept is as follows: Firstly, from a molecular / structural design perspective, functionalized bamboo fiber with dual functions of promoting interfacial reaction compatibility and degradation is self-made. Specifically, utilizing the hollow porous structure and surface active sites of bamboo fiber, metal ions are loaded after pretreatment, followed by in-situ assembly with organic ligands to further construct a reactive interfacial layer on its surface, thereby obtaining a functionalized fiber possessing metal loading capacity, interfacial compatibility regulation ability, and post-degradation promotion ability. Secondly, from a formulation design perspective, two PBAT resins with different physical properties are compounded to complement each other in terms of melt index, terminal carboxyl groups, molecular weight, and melt strength, achieving graded control of different cracking cycles at 60d, 90d, and 120d. Simultaneously, surface-treated fillers with suitable particle sizes are selected to improve the interfacial bonding and stress transfer effects of the system. Combined with specific light stabilizers, this ensures the system provides light stability in the early stages, guaranteeing mechanical integrity during service life, while avoiding excessive light competition in the later stages, thus creating conditions for rapid degradation. The theoretical basis for this is as follows: First, the hollow porous structure of bamboo fiber facilitates the adsorption and loading of metal ions; second, metal ions and organic ligands can form a stable functional layer on the fiber surface and interact with the PBAT matrix or interfacial active groups, thereby promoting interfacial compatibilization; third, the differences in molecular weight, terminal carboxyl groups, and melt flowability between the two PBAT resins can jointly regulate the early mechanical properties and later degradation rate of the mulch film; fourth, surface-treated fillers with suitable particle sizes help improve mechanical properties and influence water and oxygen transport and local degradation behavior; fifth, the light stabilizer works synergistically with the above components to achieve the goal of "stable in the early stages and rapid degradation in the later stages." The self-made functionalized bamboo fiber was mixed with compound PBAT resin, fillers, and additives, then extruded and blown into film. The components synergistically improved the mechanical properties and degradation controllability of the black mulch film for rice cultivation; simultaneously, it reduced or eliminated the use of herbicides, effectively promoting ecological agriculture. Examples of this invention are as follows: This invention provides a controllable bio-based degradable weed control film for rice, comprising the following raw materials in parts by weight: 70-90 parts of PBAT resin; Functionalized bamboo fiber 5.0-10.0 parts; 5-20 parts of modified filler; 3.0-5.0 parts of black masterbatch; Light stabilizer 0.2-0.3 parts; Antioxidant 0.2-0.5 parts; Lubricant 0.1-0.2 parts; Anti-hydrolysis agent 0.5-1.0 parts; The functionalized bamboo fiber includes a bamboo fiber matrix and a metal-organic ligand functional layer-coupling functional layer loaded on its surface and / or in its pores.

[0021] The functionalized bamboo fiber includes the following preparation steps: S11: After dispersing bamboo fiber, treat it with a 1.0 mol / L sodium hydroxide aqueous solution for 5 h, wash it with deionized water until the pH is neutral, and then dry it. The ratio of bamboo fiber to sodium hydroxide aqueous solution is 1g:100mL; The bamboo fiber is commercially available bamboo fiber with a diameter of [missing information]. .

[0022] S12: Add the product of S11 to an aqueous solution of metal ions, adjust the pH to 4.0-5.5, and treat at 20-25°C and 250 rpm for 20-60 min; so that the metal ions are adsorbed on the fiber surface and / or in the internal pores (the adsorption completion is verified by titration test of the metal ion concentration before and after treatment). The metal ion is manganese, copper or iron; its corresponding anion can be chloride, acetate or sulfate. The concentration of the metal ion is 100-300 mg / L; the liquid-to-solid ratio is 100 mL / g. S13: Transfer the product from S12 into an organic ligand solution, control the pH of the system to 4.0-5.0, and treat at 20-30°C and 250 rpm for 30-120 min; this allows the organic ligand to undergo in-situ complexation with the metal ions adsorbed on the fiber surface, thereby forming a metal-organic ligand functional layer on the surface and / or in the internal pores of the bamboo fiber (the adsorption completion is verified by titration test of the organic ligand concentration before and after treatment). The organic ligand is tartaric acid, citric acid, or malic acid; and the concentration is 4-8 mmol / L; The molar ratio of the organic ligand to the metal ion is (1.5-2.0):1.

[0023] S14: An epoxy silane coupling agent was pre-hydrolyzed in an ethanol / water mixed solvent (V / V = 80 / 20) at room temperature for 1 hour to prepare a 1 wt% treatment solution. The product from S13 was washed to remove free ligands and then immersed in the solution for 1 hour, introducing a reactive interface layer onto its surface (911 cm⁻¹ was observed after treatment, as measured by reflectance infrared spectroscopy). -1 (Epoxy group absorption peak); after washing three times with deionized water, filtering, and drying at 60-70°C to constant weight, functionalized bamboo fiber, i.e., the target product, is obtained.

[0024] The amount of the epoxy silane coupling agent and the S13 product is 1-3g:100g; and The epoxy silane coupling agent can be silane coupling agent KH560, silane coupling agent KH561, silane coupling agent KH577, silane coupling agent KH578, etc.; and preferably, silane coupling agent KH560.

[0025] The PBAT resin is a first PBAT resin and a second PBAT resin in a mass ratio of (0.2-0.8):(0.8-0.2). The first PBAT resin has a melt flow rate of 3-5 g / 10 min and a terminal carboxyl group value of 15-25 mol / t; and in the following embodiments and comparative examples of this invention, the first PBAT resin is AP11 type, with an MFR of 4.3 g / 10 min and a terminal carboxyl group value of 17.5 mol / t; purchased from Kanghui New Materials Technology Co., Ltd.; and The second PBAT resin has a melt flow rate of 3-5 g / 10 min and a terminal carboxyl group value of 7-15 mol / t; and in the following examples and comparative examples of the present invention, the second PBAT resin is of type TH801T, with an MFR of 3.7 g / 10 min and a terminal carboxyl group value of 7.5 mol / t; it was purchased from Xinjiang Lanshan Tunhe Degradable Materials Co., Ltd.

[0026] The modified filler includes one or more of the following: modified non-grain biomass filler, modified calcium carbonate, or modified talc.

[0027] The non-grain biomass fillers include wood flour, starch, or straw, etc.

[0028] The modified filler is a hydrophobically modified filler; When the modified filler is a modified non-grain biomass filler, its preparation method is as follows: A 95 wt% ethanol-water solution was prepared. Silane coupling agent KH550 was added to this ethanol-water solution to prepare a silane treatment solution. The pH was adjusted to 3 with acetic acid. Dry non-grain biomass packing material was added and mixed thoroughly. The mixture was stirred at room temperature for 12 h. The solution was filtered, and the insoluble matter was collected. The insoluble matter was then repeatedly washed with distilled water until the washings were neutral. The solution was dried at 105 °C to constant weight to obtain the hydrophobically treated modified non-grain biomass packing material. The ratio of silane coupling agent KH550 to dry non-grain biomass packing material was 5 g:95 g.

[0029] When the modified filler is modified calcium carbonate or modified talc, its preparation method is as follows: The dried talc or calcium carbonate is added to a temperature-controlled mixing device, and 1.5 wt% stearic acid is added based on the mass of the talc. The mixture is stirred at 90°C for 20 min to obtain modified talc or modified calcium carbonate.

[0030] The modified filler has a particle size of 2000-5000 mesh.

[0031] The black masterbatch is obtained by mixing carbon black and PBAT in a weight ratio of 1:2 and then extruding.

[0032] The carbon black has an average particle size of 18-30 nm and an oil absorption value of 80-110 mL / 100 g; the PBAT is type TH801T. In the preparation of the black masterbatch, the carbon black and PBAT are first dried and premixed at high speed, then melt-blended using a twin-screw extruder at 125-145℃, extruded, cooled, and granulated to obtain the black masterbatch.

[0033] The light stabilizer is a polymerizable hindered amine light stabilizer; specifically, it can be Hostavin. ™ N30P, Chimassorb ® 944, JYLSTAB-944, or JADEWIN LS 944, etc.; and, in the following embodiments and comparative examples of the present invention, the light stabilizer is Hostavin. ™ N30P.

[0034] The antioxidant is a hindered phenol; it can be antioxidant 1010, antioxidant 1076, antioxidant 264, antioxidant 2246, etc.; and, in the following embodiments and comparative examples of the present invention, the antioxidant is antioxidant 1010.

[0035] The lubricant is EBS, oleamide, or erucamide, etc.; and the lubricant used in the following embodiments and comparative examples of the present invention is EBS.

[0036] The anti-hydrolysis agent is HyMax 210, HyMax 213, HyMax 220, AHA80, stabaxol P or stabaxol I, etc.; and the anti-hydrolysis agent mentioned in the following embodiments and comparative examples of the present invention is HyMax 220.

[0037] The mechanism of action of the functionalized bamboo fiber described in this invention is mainly reflected in the following aspects: Firstly, as a biomass fiber, bamboo fiber has the advantages of hollow porous structure and high specific surface area, which are conducive to the adsorption and loading of metal ions. This allows the metal active sites to be distributed more evenly on the fiber surface and in the internal pores, thus providing stable active centers for the controlled degradation of the PBAT matrix in the later stage. Secondly, bamboo fiber itself can play a certain role in reinforcement and stress transfer in the composite system, which is beneficial to improving the initial mechanical properties of the mulch film.

[0038] Secondly, a metal-organic ligand functional layer is constructed on the surface of bamboo fiber through in-situ complexation of organic ligands with metal ions. The polar groups such as carboxyl and hydroxyl groups in the ligands not only form relatively stable coordination structures with metal ions but also enhance the polarity and interfacial activity of the fiber surface, thereby strengthening the interfacial interaction between the fiber and the PBAT resin matrix, promoting interfacial bonding, and improving the mechanical properties and interfacial stability of the composite material. Simultaneously, the metal-organic ligand functional layer can be gradually exposed in the later stages of the mulch film's service life and participate in the localized oxidative chain scission process of PBAT molecules, thus playing a role in promoting degradation.

[0039] Furthermore, a reactive epoxy-containing surface layer is introduced on the outside of the functional layer, enabling the functionalized bamboo fiber to undergo further interfacial reactions with the terminal groups of the PBAT molecular chain and / or other auxiliaries in the system during melt blending, reactive extrusion, and blown film processing. This improves the interfacial bonding strength between the fiber and the PBAT matrix, enhances dispersion uniformity, and reduces dependence on external compatibilizers, thereby improving the stability of blown film processing and the overall performance of the material.

[0040] Furthermore, due to the inherent hydrophilic conductivity and interfacial channeling properties of bamboo fiber, moisture and oxygen are more readily introduced into the PBAT interior along the fiber / matrix interface during the later stages of the mulch film's service life. This allows the metal-organic ligand functional layer loaded on the fiber surface to be exposed and function earlier, thereby achieving a controlled degradation process that extends from the local interface to the entire film. In other words, this invention does not simply rely on the homogeneous aging of the entire PBAT, but rather constructs a degradation pathway of "interface-prioritized triggering and gradual expansion to the whole" through functionalized bamboo fiber, achieving the goal of stabilizing the mulch film in its early stages and accelerating its degradation in its later stages.

[0041] Therefore, the functionalized bamboo fiber described in this invention is essentially a multi-level structural functional material with biomass fiber as the skeleton, metal-organic ligand structure as the functional center, and reactive surface layer as the interface regulation unit. The fiber skeleton provides reinforcement and porous loading, the metal-organic ligand functional layer provides interface polarity regulation, promotes later degradation, and stabilizes active sites, and the reactive surface layer further enhances its interfacial bonding and processing dispersibility with the PBAT matrix. These three components work synergistically to improve the mechanical properties and processing stability of controllable bio-based degradable weed control film for rice, and to enhance the controllability of the degradation initiation time and degradation process, thereby achieving effective regulation of the cracking and film-free periods.

[0042] Another objective of this invention is to provide a method for preparing a controllable bio-based degradable weed control film for rice, comprising the following steps: S21, raw material pretreatment, i.e. PBAT resin, functionalized bamboo fiber, filler, and black masterbatch were pretreated separately. PBAT resin was dried at 75℃ for 6 hours; functionalized bamboo fiber was dried at 85℃ for 8 hours; black masterbatch was dried at 70℃ for 3 hours; and filler was dried at 90℃ for 4 hours.

[0043] S22, Mixing, i.e. Premix the pretreated PBAT resin with black masterbatch for 2-5 minutes, then add functionalized bamboo fiber and filler and continue mixing for 3-8 minutes. Finally, add anti-hydrolysis agent, light stabilizer, and other additives and continue mixing for 2-5 minutes. The total mixing time is controlled at 8-15 minutes to obtain a relatively uniformly dispersed mixture. S23, extrusion blown film, i.e. The mixture is directly fed into a blown film extruder for melt plasticization and blown film forming; after inflation, cooling, traction and winding, a controllable bio-based biodegradable weed control film for rice is obtained.

[0044] The temperature of each zone along the feeding direction of the barrel is controlled sequentially as follows: 145-155℃, 150-160℃, 155-165℃, and 160-170℃; the temperature of the die head is controlled as 160-175℃; the screw speed is 30-50 rpm; the blowing ratio is 2.0-2.5; and the traction ratio is 3.0-4.0.

[0045] To further understand the present invention, the following detailed description of a controllable bio-based degradable weed control film for rice provided by the present invention is provided in conjunction with specific embodiments. The scope of protection of the present invention is not limited by the following embodiments. Example 1

[0046] A rice-based controllable biodegradable weed control film comprises the following raw materials in parts by weight: 80 parts of PBAT resin; Functionalized bamboo fiber, 8.0 parts; 15 parts of modified filler; 4.0 parts of black masterbatch; 0.25 parts light stabilizer; Antioxidant 0.35 parts; 0.15 parts lubricant; 0.8 parts of anti-hydrolysis agent; The functionalized bamboo fiber includes a bamboo fiber matrix and a metal-organic ligand functional layer-coupling functional layer loaded on its surface and / or in its pores.

[0047] The functionalized bamboo fiber includes the following preparation steps: S11 involves dispersing bamboo fibers and soaking them in water, then repeatedly squeezing to remove impurities and soluble substances from the fiber surface; after natural air drying, the fibers are treated with a 1.0 mol / L sodium hydroxide aqueous solution for 5 hours, washed with deionized water until the pH is neutral, and then dried.

[0048] The ratio of bamboo fiber to sodium hydroxide aqueous solution is 1g:100mL.

[0049] S12: Add the product of S11 to an aqueous solution of manganese sulfate, adjust the pH to 4.5, and treat at 23°C and 250 rpm for 40 min; so that manganese ions are adsorbed on the fiber surface and / or in the internal pores.

[0050] The concentration of manganese sulfate is 200 mg / L; the liquid-to-solid ratio is 100 mL / g.

[0051] S13: The product of S12 is transferred into a tartaric acid solution, the pH of the system is controlled at 4.5, and it is treated at 25°C and 250 rpm for 60 min; this allows the tartaric acid to undergo in-situ complexation with the metal ions adsorbed on the fiber surface, thereby forming a metal-tartaric acid functional layer on the surface and / or in the internal pores of the bamboo fiber.

[0052] The concentration of tartaric acid was 6 mmol / L; The molar ratio of tartaric acid to metal ions is 1.7:1.

[0053] S14: Silane coupling agent KH560 was pre-hydrolyzed in an ethanol / water mixed solvent (V / V=80 / 20) at room temperature for 1 hour to prepare a 1wt% treatment solution; the product of S13 was washed to remove free tartaric acid and then impregnated in the solution for 1 hour to introduce a reactive interface layer on its surface; after washing three times with deionized water, filtering, and drying at 65°C to constant weight, functionalized bamboo fiber, i.e., the target product, was obtained.

[0054] The ratio of the silane coupling agent KH560 to the S13 product is 1g:100g.

[0055] The PBAT resin is a first PBAT resin and a second PBAT resin in a mass ratio of 0.4:0.6.

[0056] The modified filler is modified calcium carbonate with a particle size of 2500 mesh.

[0057] A method for preparing a rice-based biodegradable weed control film includes the following steps: S21, raw material pretreatment, i.e. PBAT resin, functionalized bamboo fiber, filler, and black masterbatch were pretreated separately. PBAT resin was dried at 75℃ for 6 hours; functionalized bamboo fiber was dried at 85℃ for 8 hours; black masterbatch was dried at 70℃ for 3 hours; and filler was dried at 90℃ for 4 hours.

[0058] S22, Mixing, i.e. Pre-treated PBAT resin and black masterbatch were pre-mixed for 4 minutes, then functionalized bamboo fiber and filler were added and mixed for another 5 minutes. Finally, anti-hydrolysis agent, light stabilizer, and other additives were added and mixed for another 3 minutes. The total mixing time was controlled to 12 minutes, resulting in a relatively uniformly dispersed mixture. S23, extrusion blown film, i.e. The mixture is directly fed into a blown film extruder for melt plasticization and blown film forming; after inflation, cooling, traction and winding, a controllable bio-based biodegradable weed control film for rice is obtained.

[0059] The temperature of each zone along the feeding direction of the barrel is controlled sequentially at 150℃, 155℃, 160℃, and 165℃, and the temperature of the die head is controlled at 165℃; the screw speed is 40 rpm; the blowing ratio is 2.2; and the traction ratio is 3.5. Example 2

[0060] A rice-based controllable biodegradable weed control film comprises the following raw materials in parts by weight: 90 parts of PBAT resin; 5.0 parts of functionalized bamboo fiber; 5 parts of modified filler; 5.0 parts of black masterbatch; 0.3 parts light stabilizer; Antioxidant 0.5 parts; 0.1 parts lubricant; 1.0 part of anti-hydrolysis agent; The functionalized bamboo fiber includes a bamboo fiber matrix and a metal-organic ligand functional layer-coupling functional layer loaded on its surface and / or in its pores.

[0061] The functionalized bamboo fiber includes the following preparation steps: S11 involves dispersing bamboo fibers and soaking them in water, then repeatedly squeezing to remove impurities and soluble substances from the fiber surface; after natural air drying, the fibers are treated with a 1.0 mol / L sodium hydroxide aqueous solution for 5 hours, washed with deionized water until the pH is neutral, and then dried.

[0062] The ratio of bamboo fiber to sodium hydroxide aqueous solution is 1g:100mL.

[0063] S12: Add the product of S11 to an aqueous solution of copper sulfate, adjust the pH to 5.5, and treat at 20°C and 250 rpm for 60 min; so that copper ions are adsorbed on the fiber surface and / or in the internal pores.

[0064] The concentration of copper sulfate is 100 mg / L; the liquid-to-solid ratio is 100 mL / g.

[0065] S13: The product of S12 is transferred into a malic acid solution, the pH of the system is controlled at 5.0, and it is treated at 30°C and 250 rpm for 120 min; this allows the malic acid to undergo in-situ complexation with the metal ions adsorbed on the fiber surface, thereby forming a metal-malic acid functional layer on the surface and / or in the internal pores of the bamboo fiber.

[0066] The concentration of malic acid was 8 mmol / L; The molar ratio of malic acid to metal ions is 2.0:1.

[0067] S14: Silane coupling agent KH560 was pre-hydrolyzed in an ethanol / water mixed solvent (V / V=80 / 20) at room temperature for 1 hour to prepare a 1wt% treatment solution; the product of S13 was washed to remove free malic acid and then impregnated in the solution for 1 hour to introduce a reactive interface layer on its surface; after washing three times with deionized water, filtering, and drying at 70°C to constant weight, functionalized bamboo fiber, i.e., the target product, was obtained.

[0068] The ratio of the silane coupling agent KH560 to the S13 product is 2g:100g.

[0069] The PBAT resin is a first PBAT resin and a second PBAT resin in a mass ratio of 0.2:0.8.

[0070] The modified filler is modified talc powder with a particle size of 2500 mesh.

[0071] A method for preparing a rice-based biodegradable weed control film includes the following steps: S21, raw material pretreatment, i.e. PBAT resin, functionalized bamboo fiber, filler, and black masterbatch were pretreated separately. PBAT resin was dried at 75℃ for 6 hours; functionalized bamboo fiber was dried at 85℃ for 8 hours; black masterbatch was dried at 70℃ for 3 hours; and filler was dried at 90℃ for 4 hours.

[0072] S22, Mixing, i.e. Pre-treated PBAT resin and black masterbatch were pre-mixed for 4 minutes, then functionalized bamboo fiber and filler were added and mixed for another 5 minutes. Finally, anti-hydrolysis agent, light stabilizer, and other additives were added and mixed for another 3 minutes. The total mixing time was controlled to 12 minutes, resulting in a relatively uniformly dispersed mixture. S23, extrusion blown film, i.e. The mixture is directly fed into a blown film extruder for melt plasticization and blown film forming; after inflation, cooling, traction and winding, a controllable bio-based biodegradable weed control film for rice is obtained.

[0073] The temperature of each zone along the feeding direction of the barrel is controlled sequentially at 155℃, 160℃, 165℃, and 170℃, while the temperature of the die head is controlled at 175℃; the screw speed is 30 rpm; the blowing ratio is 2.5; and the traction ratio is 3.0. Example 3

[0074] A rice-based controllable biodegradable weed control film comprises the following raw materials in parts by weight: 70 parts of PBAT resin; 10.0 parts of functionalized bamboo fiber; 20 parts of modified filler; 3.0 parts black masterbatch; 0.2 parts light stabilizer; Antioxidant 0.2 parts; 0.2 parts lubricant; 0.5 parts of anti-hydrolysis agent; The functionalized bamboo fiber includes a bamboo fiber matrix and a metal-organic ligand functional layer-coupling functional layer loaded on its surface and / or in its pores.

[0075] The functionalized bamboo fiber includes the following preparation steps: S11 involves dispersing bamboo fibers and soaking them in water, then repeatedly squeezing to remove impurities and soluble substances from the fiber surface; after natural air drying, the fibers are treated with a 1.0 mol / L sodium hydroxide aqueous solution for 5 hours, washed with deionized water until the pH is neutral, and then dried.

[0076] The ratio of bamboo fiber to sodium hydroxide aqueous solution is 1g:100mL.

[0077] S12: Add the product of S11 to an aqueous solution of ferric chloride, adjust the pH to 4.0, and treat at 25°C and 250 rpm for 20 min; so that iron ions are adsorbed on the fiber surface and / or in the internal pores.

[0078] The concentration of ferric chloride is 300 mg / L; the liquid-to-solid ratio is 100 mL / g. S13: The product of S12 is transferred into a citric acid solution, the pH of the system is controlled at 4.0, and it is treated at 20°C and 250 rpm for 30 min; this allows the citric acid to undergo in-situ complexation with the metal ions adsorbed on the fiber surface, thereby forming a metal-citric acid functional layer on the surface and / or in the internal pores of the bamboo fiber. The concentration of citric acid is 4 mmol / L; The molar ratio of citric acid to metal ions is 1.5:1.

[0079] S14: Silane coupling agent KH560 was pre-hydrolyzed in an ethanol / water mixed solvent (V / V=80 / 20) at room temperature for 1 hour to prepare a 1wt% treatment solution; the product of S13 was washed to remove free citric acid and then impregnated in the solution for 1 hour to introduce a reactive interface layer on its surface; after washing three times with deionized water, filtering, and drying at 60°C to constant weight, functionalized bamboo fiber, i.e., the target product, was obtained.

[0080] The ratio of the silane coupling agent KH560 to the S13 product is 3g:100g.

[0081] The PBAT resin is a first PBAT resin and a second PBAT resin in a mass ratio of 0.8:0.2.

[0082] The modified filler is made by adding modified starch and modified calcium carbonate in a mass ratio of 3 / 1; wherein the modified starch has a particle size of 2000 mesh and the modified calcium carbonate has a particle size of 2500 mesh.

[0083] A method for preparing a rice-based biodegradable weed control film includes the following steps: S21, raw material pretreatment, i.e. PBAT resin, functionalized bamboo fiber, filler, and black masterbatch were pretreated separately. PBAT resin was dried at 75℃ for 6 hours; functionalized bamboo fiber was dried at 85℃ for 8 hours; black masterbatch was dried at 70℃ for 3 hours; and filler was dried at 90℃ for 4 hours.

[0084] S22, Mixing, i.e. Pre-treated PBAT resin and black masterbatch were pre-mixed for 4 minutes, then functionalized bamboo fiber and filler were added and mixed for another 5 minutes. Finally, anti-hydrolysis agent, light stabilizer, and other additives were added and mixed for another 3 minutes. The total mixing time was controlled to 12 minutes, resulting in a relatively uniformly dispersed mixture. S23, extrusion blown film, i.e. The mixture is directly fed into a blown film extruder for melt plasticization and blown film forming; after inflation, cooling, traction and winding, a controllable bio-based biodegradable weed control film for rice is obtained.

[0085] The temperature of each zone along the feeding direction of the barrel is controlled sequentially as 145℃, 150℃, 155℃, and 160℃, and the temperature of the die head is controlled as 160℃; the screw speed is 50 rpm; the blowing ratio is 2.0; and the traction ratio is 4.0. Example 4

[0086] Everything else is the same as in Example 1, except that: The PBAT resin is a first PBAT resin and a second PBAT resin in a mass ratio of 0.3:0.7. Example 5

[0087] Everything else is the same as in Example 1, except that: The PBAT resin is a first PBAT resin and a second PBAT resin in a mass ratio of 0.5:0.5. Example 6

[0088] Everything else is the same as in Example 1, except that: The modified filler is 10 parts by weight. Example 7

[0089] Everything else is the same as in Example 1, except that: The modified filler is 20 parts by weight.

[0090] The following comparative examples are all compared with specific embodiment 1: Comparative Example 1 Everything else is the same as in Example 1, except that: The functionalized bamboo fiber has a weight fraction of 0 parts; that is, no such component was added.

[0091] Comparative Example 2 Everything else is the same as in Example 1, except that: The functionalized bamboo fiber includes a bamboo fiber matrix and a metal-organic ligand functional layer loaded on its surface and / or pores; the preparation steps are specifically without the S14 reactive interface layer construction step; that is, the surface of the functionalized bamboo fiber does not contain an epoxy-based coupling functional layer.

[0092] Implement Comparative Example 3 Everything else is the same as in Example 1, except that: The functionalized bamboo fiber comprises a bamboo fiber matrix and a coupling functional layer loaded on its surface and / or pores; the specific preparation steps are as follows: S11 involves dispersing bamboo fibers and soaking them in water, then repeatedly squeezing to remove impurities and soluble substances from the fiber surface; after natural air drying, the fibers are treated with a 1.0 mol / L sodium hydroxide aqueous solution for 5 hours, washed with deionized water until the pH is neutral, and then dried.

[0093] The ratio of bamboo fiber to sodium hydroxide aqueous solution is 1g:100mL.

[0094] S12: Prepare a 1wt% treatment solution by pre-hydrolyzing silane coupling agent KH560 in an ethanol / water mixed solvent (V / V=80 / 20) at room temperature for 1 hour; then immerse the S11 product in the solution for 1 hour to introduce a reactive interface layer on its surface.

[0095] The ratio of the silane coupling agent KH560 to the S11 product is 1g:100g.

[0096] Comparative Example 4 Everything else is the same as in Example 1, except that: The functionalized bamboo fiber is replaced with functionalized cotton fiber; in the specific preparation steps, the bamboo fiber in S11 is replaced with cotton fiber.

[0097] Comparative Example 5 Everything else is the same as in Example 1, except that: The PBAT resin is the first PBAT resin.

[0098] Comparative Example 6 Everything else is the same as in Example 1, except that: The PBAT resin is a second PBAT resin.

[0099] Comparative Example 7 Everything else is the same as in Example 1, except that: The modified filler was replaced with a filler that was not hydrophobically modified.

[0100] Implemented Comparative Example 8 Everything else is the same as in Example 1, except that: The modified filler has a particle size of 1000 mesh.

[0101] Comparative Example 9 Everything else is the same as in Example 1, except that: The light stabilizer was replaced with a UV absorber (UV-234).

[0102] Implement Comparative Example 10 Everything else is the same as in Example 1, except that: The light stabilizer was replaced with a small molecule light stabilizer (UV-292).

[0103] The results of measuring the physical properties of the rice-based controlled bio-based degradable weed control film in the embodiments and comparative examples of the present invention are shown in Table 1.

[0104] Table 1 Physical performance tests of each embodiment First, as can be seen from Examples 1-7 in Table 1, the rice-based controllable biodegradable weed control film of the present invention has excellent mechanical properties and controllable degradation ability (the cracking period is mainly within the range of 60 days, 90 days and 120 days respectively; and the degradation from the cracking period to the film-free period is completed in a relatively short time (within 20 days).

[0105] Secondly, as can be observed from Example 1 and Comparative Examples 1-4, the rice-based controllable biodegradable weed control film of the present invention uses self-made functionalized bamboo fiber, which promotes interfacial reaction, increases mechanical properties, and accelerates degradation. The hollow porous structure of the bamboo fiber effectively enhances the loading capacity of metal ions, thus exhibiting excellent degradation-promoting properties. As can be observed from Example 1 and Comparative Examples 5-6, the combined use of two types of PBAT in the present invention has a positive effect on controllable degradation. As can be observed from Example 1 and Comparative Examples 7-8, the surface treatment of the filler and the appropriate particle size have a positive impact on both mechanical properties and degradation rate. As can be observed from Example 1 and Comparative Examples 9-10, the light stabilizer of the present invention provides photostable effect in the early stage compared to small molecule structures; and compared to ultraviolet absorbers, it does not participate in light competition in the later stage, providing rapid degradation.

[0106] In summary, the present invention provides a controllable bio-based degradable weed control film for rice. On the one hand, it uses molecular design to create functionalized bamboo fiber; on the other hand, it uses formulation design to utilize the synergistic effect of compounded PBAT resin, suitable fillers, and additives to effectively improve the mechanical properties and controllable degradation of the PBAT black film, which has broad application prospects.

[0107] The testing method is as follows: (1) Mechanical properties: tested according to the method described in GB / T 1040.3-2006.

[0108] (2) Degradation status: According to the experimental design, the degradation of the mulch film was divided into two stages: cracking stage (the mulch film begins to crack) and no-film stage (the mulch film is completely degraded). The duration of each stage was monitored and recorded to characterize the degradation status of the mulch film.

[0109] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A controllable bio-based degradable weed control film for rice, characterized in that, Including the following parts by weight of raw materials: 70-90 parts of PBAT resin; Functionalized bamboo fiber 5.0-10.0 parts; 5-20 parts of modified filler; 3.0-5.0 parts of black masterbatch; Light stabilizer 0.2-0.3 parts; Antioxidant 0.2-0.5 parts; Lubricant 0.1-0.2 parts; Anti-hydrolysis agent 0.5-1.0 parts; The functionalized bamboo fiber includes a bamboo fiber matrix and a metal-organic ligand functional layer-coupling functional layer loaded on its surface and / or in its pores.

2. The rice-based controllable biodegradable weed control film according to claim 1, characterized in that, The functionalized bamboo fiber includes the following preparation steps: S11, bamboo fiber pretreatment, i.e. Bamboo fibers are subjected to alkali washing, dried after washing, and then crushed or chopped to obtain pretreated bamboo fibers. S12, metal ion adsorption, i.e. Add the S11 product to the metal ion solution to allow the metal ions to be adsorbed on the fiber surface and / or in the internal pores. S13, organic ligand assembly, i.e. The S12 product is transferred into an organic ligand solution, which allows the organic ligand to undergo in-situ complexation with the metal ions adsorbed on the fiber surface, thereby forming a metal-organic ligand functional layer on the surface and / or in the internal pores of the bamboo fiber. S14, Construction of reactive interface layer, i.e. The S13 product is contacted with an epoxy-containing surface treatment agent to introduce a reactive interface layer on its surface; after post-treatment, functionalized bamboo fiber, i.e., the target product, is obtained.

3. The rice-based controllable biodegradable weed control film according to claim 2, characterized in that, The metal ion is manganese, copper, or iron; and The organic ligand is tartaric acid, citric acid, or malic acid.

4. The rice-based controllable biodegradable weed control film according to claim 1, characterized in that, The PBAT resin is composed of a first PBAT resin and a second PBAT resin in a mass ratio of (0.2-0.8):(0.8-0.2). The first PBAT resin has a melt flow rate of 3-5 g / 10 min and a terminal carboxyl group value of 15-25 mol / t; and The melt flow rate of the second PBAT resin is 3-5 g / 10 min, and the terminal carboxyl group value is 7-15 mol / t.

5. The rice-based controllable biodegradable weed control film according to claim 1, characterized in that, The modified filler includes one or more of the following: modified non-grain biomass filler, modified calcium carbonate, or modified talc.

6. The rice-based controllable biodegradable weed control film according to claim 1 or 5, characterized in that, The modified filler is a hydrophobically modified filler with a particle size of 2000-5000 mesh.

7. The rice-based controllable biodegradable weed control film according to claim 1, characterized in that, The black masterbatch is obtained by mixing carbon black and PBAT in a weight ratio of 1:2 and then extruding.

8. The rice-based controllable biodegradable weed control film according to claim 1, characterized in that, The light stabilizer is a polymeric hindered amine light stabilizer.

9. The method for preparing a rice-based controllable biodegradable weed control film according to claim 1, characterized in that, Includes the following steps: S21, raw material pretreatment, i.e. PBAT resin, functionalized bamboo fiber, filler, and black masterbatch were pretreated separately. S22, Mixing, i.e. Add the ingredients according to the formula to a mixer and mix for 5-20 minutes to obtain a mixture; and S23, extrusion blown film, i.e. The mixture is directly fed into a blown film extruder for melt plasticizing and blown film forming to obtain a controllable bio-based biodegradable weed control film for rice.

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