Black mulching film for rice cultivation and preparation method thereof

Abstract

The invention discloses a black mulching film for rice cultivation and a preparation method thereof, and relates to the technical field of agricultural high polymer materials. When the black mulching film for rice cultivation is prepared, 1, 4-butanediol, butanedioic anhydride and itaconic acid are subjected to vacuum polycondensation to prepare a poly (butylene succinate)-itaconic acid block copolymer; performing esterification reaction on starch and octenyl succinic anhydride to obtain modified starch; the preparation method comprises the following steps: pyrolyzing corn straws to prepare biological carbon black, carrying out acid pickling activation, loading abamectin, and carrying out surface modification by using 3-mercaptopropyltrimethoxysilane to prepare surface-modified drug-loaded biological-based carbon black powder; and mixing the poly (butylene succinate)-itaconic acid segmented copolymer, modified starch, the surface modified drug-loaded bio-based carbon black powder and glycerol according to a ratio, performing twin-screw extrusion, promoting a click chemical reaction between double bonds and sulfydryl, performing granulation, and performing blow molding to obtain the black mulching film for rice cultivation. The prepared black mulching film for rice cultivation has biodegradability, excellent mechanical properties and a slow-release insecticidal function.

Description

Technical Field

[0001] This invention relates to the field of agricultural polymer materials technology, specifically to a black mulch film for rice cultivation and its preparation method. Background Technology

[0002] Polybutylene succinate (PBS) is an important class of biodegradable aliphatic polyester materials. It is solid at room temperature and possesses good biocompatibility and processing properties. Due to its excellent mechanical properties and biodegradability, PBS-based materials show application potential in packaging, agricultural mulch films, and other fields. However, conventional PBS mulch films still suffer from problems such as limited functionality, lack of insecticidal agronomical functions, potentially insufficient mechanical properties in complex field environments, high costs due to complete reliance on petroleum-based monomers, and failure to maximize the utilization of biomass resources. Furthermore, while traditional polyolefin mulch films are widely used, their raw material preparation consumes large amounts of petroleum resources and is difficult to degrade in the natural environment, resulting in "white pollution" after disposal and placing long-term pressure on soil health and the ecological environment.

[0003] In recent years, with the advancement of sustainable agricultural development and increasingly stringent environmental regulations, mulching technologies such as rice cultivation have placed higher demands on the biodegradability, environmental friendliness, multifunctionality, and bio-based nature of mulch films. Therefore, in order to conserve petroleum resources, reduce environmental pressure, and improve the field performance of mulch films, it is necessary to develop bio-based biodegradable polyester composite mulch film materials that use renewable resources as raw materials and possess good mechanical properties, controllable degradation, and multifunctionality. Summary of the Invention

[0004] The purpose of this invention is to provide a black mulch film for rice cultivation and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A black mulch film for rice cultivation is prepared by mixing polybutylene succinate-itaconic acid block copolymer, modified starch, and surface-modified drug-loaded bio-based carbon black powder, followed by granulation and blow molding.

[0007] As an optimization, the polybutylene succinate-itaconic acid block copolymer is prepared by vacuum polycondensation of 1,4-butanediol, succinic anhydride and itaconic acid.

[0008] As an optimization, the modified starch is prepared by esterification reaction of starch with octenyl succinic anhydride.

[0009] As an optimization, the surface-modified drug-loaded bio-based carbon black powder is prepared by pyrolysis of corn stalks to produce bio-carbon black, which is then acid-washed and activated, loaded with avermectin, and then surface-modified with 3-mercaptopropyltrimethoxysilane.

[0010] A method for preparing black plastic film for rice cultivation includes the following preparation steps:

[0011] (1) In a nitrogen atmosphere, 1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate were mixed evenly in a mass ratio of 1:(0.75~0.95):(0.1~0.3):(0.0004~0.0008) and stirred at 130~170℃ and 200~400r / min for 1~3h. Then, 0.001~0.005 times the mass of 1,4-butanediol was added to tetrabutyl titanate, and the temperature was raised to 180~220℃. The reaction was continued under vacuum for 2~6h to obtain double bond functionalized polybutylene succinate-itaconic acid block copolymer.

[0012] (2) Mix starch and anhydrous pyridine at a mass ratio of 1:8~12, treat with ultrasonic power of 200~500W for 20~40min to form a uniform starch suspension, add octenyl succinic anhydride at a mass of 3%~8% of the dry weight of starch, stir at 25~45℃ and 200~400r / min for 6~10h, centrifuge, wash with deionized water and acetone 2~3 times in sequence, dry, and obtain modified starch;

[0013] (3) Soak corn stalk bio-carbon black powder in 8%~12% sulfuric acid for 6~8h, wash until neutral, dry to obtain pretreated bio-carbon black powder; Soak the pretreated bio-carbon black powder in 2%~5% abamectin acetone solution, treat under ultrasonic power of 200~500W for 20~40min to form a uniform suspension, vacuum impregnate for 2~6h, filter, wash with acetone 1~3 times, vacuum dry in the dark to obtain insecticide-loaded carbon black powder; Mix insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone at a mass ratio of 1:(0.1~0.5):(10~12) evenly, stir at 200~400r / min for 0.5~1.5h, dry at 60~80°C for 12~24h to obtain surface-modified insecticide-loaded bio-based carbon black powder;

[0014] (4) The double-bond functionalized polybutylene succinate-itaconic acid block copolymer, modified starch, surface-modified loaded insecticide bio-based carbon black powder and glycerin are mixed evenly at a mass ratio of 1:(0.25~0.45):(0.08~0.12):(0.05~0.15) and then added to a twin-screw extruder. The barrel temperature from the feeding zone to the die zone is set to 105, 115, 130, 140, 130 and 100℃, and the screw speed is set to 160~180rpm. The extrudate is cut into granules after air cooling. The obtained granules are fed into a blown film machine to blow film and obtain black mulch for rice cultivation.

[0015] As an optimization, the reaction process of the double-bond functionalized polybutylene succinate-itaconic acid block copolymer in step (1) is as follows:

[0016] As an optimization, the starch in step (2) is cassava starch with a straight-chain starch content of 25%, manufactured by Jiangxi Boda Chemical Co., Ltd.

[0017] As an optimization, the corn stalks in step (3) are collected from local farms in Sichuan, China.

[0018] As an optimization, the preparation method of the corn stalk bio-carbon black powder in step (3) is as follows: the corn stalk is dried at 95~115°C for 18~24h, ground, and then the ground corn stalk is placed in a heating reactor and pyrolyzed at 500~800°C for 1~3h. After grinding, it is passed through 200 mesh and 325 mesh standard sieves in sequence, and the material under the 325 mesh sieve is collected to obtain corn stalk bio-carbon black powder with a particle size of 35~45μm.

[0019] As an optimization, the method for blowing black plastic film for rice cultivation in step (4) is as follows: the obtained granules are fed into a blown film machine, and the melt is extruded at a screw speed of 30-70 r / min under the temperature settings of 140-160℃ in the feeding section, 160-180℃ in the compression section and 180-200℃ in the melting section. The melt is blown, cooled and pulled at a blowing ratio of 2.0-3.0 and a traction speed of 15-30 m / min, and finally rolled up to obtain black plastic film for rice cultivation.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0021] In preparing black mulch for rice cultivation, this invention involves vacuum polycondensation of 1,4-butanediol, succinic anhydride, and itaconic acid to obtain polybutylene succinate-itaconic acid block copolymer; esterification of starch with octenyl succinic anhydride to obtain modified starch; pyrolysis of corn stalks to produce biochar black, which is then acid-washed and activated, loaded with avermectin, and surface-modified with 3-mercaptopropyltrimethoxysilane to obtain surface-modified drug-loaded biochar black powder; and mixing the polybutylene succinate-itaconic acid block copolymer, modified starch, surface-modified drug-loaded biochar black powder, and glycerol in a specific ratio, followed by twin-screw extrusion to promote the click reaction between double bonds and thiol groups, granulation, and blow molding to obtain the black mulch for rice cultivation.

[0022] First, in the double-bond functionalized polybutylene succinate-itaconic acid block copolymer synthesized using bio-based monomers, 1,4-butanediol, succinic anhydride, and itaconic acid, the itaconic acid unit introduces a rigid cyclic structure and active carbon-carbon double bonds into the polyester backbone, which not only significantly enhances the tear resistance and toughness of the material but also provides reaction sites for subsequent crosslinking. Then, starch is introduced into the mulch film. Octenyl succinic anhydride-modified starch improves the compatibility with polyester through long-chain alkenyl hydrophobic groups, while retaining a large number of hydroxyl structures in the starch molecule that can be recognized by microorganisms, significantly accelerating the biodegradation process of the mulch film in the soil environment.

[0023] Secondly, after the corn stalk biochar black is activated with sulfuric acid to expand its pore structure and regulate the oxygen-containing groups on its surface, it is efficiently loaded with abamectin insecticide, and then a dense thiol functionalized layer is constructed by surface modification with 3-mercaptopropyltrimethoxysilane. After surface polarity regulation, bio-carbon black particles are uniformly dispersed in polyester melt, giving the mulch film a durable and stable pure black color, completely eliminating light transmittance to inhibit weed photosynthesis. Furthermore, during the melt blending process, the thiol groups on the carbon black surface undergo an efficient thiol-ene click reaction with the carbon-carbon double bonds of the itaconic acid block in the polyester, forming a covalent cross-linked network of "polyester-carbon black" in situ, significantly enhancing the material's puncture resistance and weather resistance. At the same time, the multi-level pores of activated carbon black enable high loading of abamectin, which is released slowly and effectively through pore diffusion, effectively repelling underground pests in rice fields. Combined with the melt flow optimized by the plasticizing effect of glycerol, this design allows the mulch film to maintain complete biodegradability while integrating mechanical strengthening, precise coloring, pest control, and photothermal weed suppression, fundamentally breaking through the non-degradable pollution and functional limitations of traditional polyolefin mulch films. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] To more clearly illustrate the method provided by the present invention, the following embodiments will be described in detail.

[0026] Example 1:

[0027] A method for preparing black plastic film for rice cultivation mainly includes the following preparation steps:

[0028] (1) In a nitrogen atmosphere, 1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate were mixed evenly in a mass ratio of 1:0.75:0.2:0.0004 and stirred at 130°C and 200 r / min for 1 h. Then, 0.003 times the mass of 1,4-butanediol was added to tetrabutyl titanate, the temperature was raised to 200°C, and the reaction was continued under vacuum for 4 h to obtain double bond functionalized polybutylene succinate-itaconic acid block copolymer;

[0029] (2) Mix starch and anhydrous pyridine at a mass ratio of 1:8, treat with ultrasonic power of 200W for 20min to form a uniform starch suspension, add octenyl succinic anhydride at 3% of the dry weight of starch, stir at 25℃ and 200r / min for 6h, centrifuge, wash twice with deionized water and acetone, dry, and obtain modified starch.

[0030] (3) The corn stalks were dried at 95°C for 18 hours, ground, and then placed in a heating reactor. The pyrolysis was carried out at 500°C for 1 hour. The stalks were then ground and passed through a 200-mesh and a 325-mesh standard sieve. The material passing through the 325-mesh sieve was collected to obtain corn stalk biochar black powder with a particle size of 35 μm. The corn stalk biochar black powder was soaked in 8% sulfuric acid for 6 hours, washed until neutral, and dried to obtain pretreated biochar black powder. The pretreated biochar black powder was then soaked in 2% ammonia solution. A vitamin acetone solution was treated with ultrasound at 200W for 20 minutes to form a uniform suspension. The suspension was then vacuum impregnated for 2 hours, filtered, washed once with acetone, and dried under vacuum in the dark to obtain insecticide-loaded carbon black powder. The insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane, and acetone were mixed uniformly at a mass ratio of 1:0.3:10, stirred at 200 r / min for 1 hour, and dried at 60°C for 12 hours to obtain surface-modified insecticide-loaded bio-based carbon black powder.

[0031] (4) Double bond functionalized polybutylene succinate-itaconic acid block copolymer, modified starch, surface-modified loaded insecticide bio-based carbon black powder and glycerin are mixed evenly at a mass ratio of 1:0.35:0.08:0.05 and added to a twin-screw extruder. The barrel temperature from the feeding zone to the die zone is set to 105, 115, 130, 140, 130 and 100℃, and the screw speed is set to 160rpm. The extrudate is cut into granules after air cooling. The obtained granules are fed into a blown film machine. The melt is extruded at a screw speed of 30r / min under the temperature settings of 140℃ in the feeding section, 160℃ in the compression section and 180℃ in the melting section. The blown film is blown, cooled and pulled at a blown ratio of 2.0 and a traction speed of 15m / min. Finally, the black mulch film for rice cultivation is rolled up.

[0032] Example 2:

[0033] A method for preparing black plastic film for rice cultivation mainly includes the following preparation steps:

[0034] (1) In a nitrogen atmosphere, 1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate were mixed evenly in a mass ratio of 1:0.85:0.2:0.0006 and stirred at 150°C and 300 r / min for 2 h. Then, 0.003 times the mass of 1,4-butanediol was added to tetrabutyl titanate, the temperature was raised to 200°C, and the reaction was continued under vacuum for 4 h to obtain double bond functionalized polybutylene succinate-itaconic acid block copolymer;

[0035] (2) Mix starch and anhydrous pyridine at a mass ratio of 1:10, treat with ultrasonic power of 350W for 30min to form a uniform starch suspension, add octenyl succinic anhydride at a mass of 5.5% of the dry weight of starch, stir at 35℃ and 300r / min for 8h, centrifuge, wash with deionized water and acetone three times in sequence, dry, and obtain modified starch;

[0036] (3) The corn stalks were dried at 105°C for 22 hours, ground, and then placed in a heating reactor. The mixture was pyrolyzed at 650°C for 2 hours, ground again, and passed through 200-mesh and 325-mesh standard sieves. The material passing through the 325-mesh sieve was collected to obtain corn stalk biochar black powder with a particle size of 40 μm. The corn stalk biochar black powder was soaked in 10% sulfuric acid for 7 hours, washed until neutral, and dried to obtain pretreated biochar black powder. The pretreated biochar black powder was then immersed in 3.5... A % abamectin acetone solution was treated with ultrasound at 350W for 30 min to form a uniform suspension. The suspension was then vacuum impregnated for 4 h, filtered, washed twice with acetone, and dried under vacuum in the dark to obtain insecticide-loaded carbon black powder. The insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane, and acetone were mixed uniformly at a mass ratio of 1:0.3:11, stirred at 300 r / min for 1 h, and dried at 70°C for 18 h to obtain surface-modified insecticide-loaded bio-based carbon black powder.

[0037] (4) Double bond functionalized polybutylene succinate-itaconic acid block copolymer, modified starch, surface-modified loaded insecticide bio-based carbon black powder and glycerin are mixed evenly at a mass ratio of 1:0.35:0.1:0.1 and then added to a twin-screw extruder. The barrel temperature from the feeding zone to the die zone is set to 105, 115, 130, 140, 130 and 100℃, and the screw speed is set to 170rpm. The extrudate is cut into granules after air cooling. The obtained granules are fed into a blown film machine. The melt is extruded at a screw speed of 50r / min under the temperature settings of 150℃ in the feeding section, 170℃ in the compression section and 190℃ in the melting section. The blown film is blown, cooled and pulled at a blown ratio of 3.0 and a traction speed of 25m / min. Finally, the black mulch film for rice cultivation is rolled up.

[0038] Example 3:

[0039] A method for preparing black plastic film for rice cultivation mainly includes the following preparation steps:

[0040] (1) In a nitrogen atmosphere, 1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate were mixed evenly in a mass ratio of 1:0.95:0.2:0.0008 and stirred at 170°C and 400 r / min for 3 h. Then, 0.003 times the mass of 1,4-butanediol was added to tetrabutyl titanate, the temperature was raised to 200°C, and the reaction was continued for 4 h under vacuum to obtain double bond functionalized polybutylene succinate-itaconic acid block copolymer;

[0041] (2) Mix starch and anhydrous pyridine at a mass ratio of 1:12, treat with ultrasonic power of 500W for 40 min to form a uniform starch suspension, add octenyl succinic anhydride at 8% of the dry weight of starch, stir at 45℃ and 400r / min for 10 h, centrifuge, wash with deionized water and acetone three times in sequence, dry, and obtain modified starch.

[0042] (3) The corn stalks were dried at 115°C for 24 hours, ground, and then placed in a heating reactor. The mixture was pyrolyzed at 800°C for 3 hours, ground, and passed through 200-mesh and 325-mesh standard sieves. The material passing through the 325-mesh sieve was collected to obtain corn stalk biochar black powder with a particle size of 45 μm. The corn stalk biochar black powder was soaked in 12% sulfuric acid for 8 hours, washed until neutral, and dried to obtain pretreated biochar black powder. The pretreated biochar black powder was then immersed in 5% sulfuric acid. Abamectin acetone solution was treated with ultrasonic power 500W for 40 min to form a uniform suspension, vacuum impregnated for 6 h, filtered, washed 3 times with acetone, and vacuum dried in the dark to obtain insecticide-loaded carbon black powder; the insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone were mixed uniformly at a mass ratio of 1:0.3:12, stirred at 400 r / min for 1 h, and dried at 80°C for 24 h to obtain surface-modified insecticide-loaded bio-based carbon black powder;

[0043] (4) Double bond functionalized polybutylene succinate-itaconic acid block copolymer, modified starch, surface-modified loaded insecticide bio-based carbon black powder and glycerin are mixed evenly at a mass ratio of 1:0.35:0.12:0.15 and added to a twin-screw extruder. The barrel temperature from the feeding zone to the die zone is set to 105, 115, 130, 140, 130 and 100℃, and the screw speed is set to 180rpm. The extrudate is cut into granules after air cooling. The obtained granules are fed into a blown film machine. The melt is extruded at a screw speed of 70r / min under the temperature settings of 160℃ in the feeding section, 180℃ in the compression section and 200℃ in the melting section. The blown film is blown, cooled and pulled at a blown ratio of 3.0 and a traction speed of 30m / min. Finally, the black mulch film for rice cultivation is rolled up.

[0044] Comparative Example 1:

[0045] The only difference from Example 2 is the step (1), where “1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate are mixed evenly in a nitrogen atmosphere at a mass ratio of 1:0.85:0.2:0.0006” is changed to “1,4-butanediol, succinic acid, itaconic acid and zirconium acetylacetonate are mixed evenly in a nitrogen atmosphere at a mass ratio of 1:0.85:0.1:0.0006”.

[0046] Comparative Example 2:

[0047] The only difference from Example 2 is the step (1), where “1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate are mixed evenly in a nitrogen atmosphere at a mass ratio of 1:0.85:0.2:0.0006” is changed to “1,4-butanediol, succinic acid, itaconic acid and zirconium acetylacetonate are mixed evenly in a nitrogen atmosphere at a mass ratio of 1:0.85:0.15:0.0006”.

[0048] Comparative Example 3:

[0049] The only difference from Example 2 is the step (1), where “1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate are mixed evenly in a nitrogen atmosphere at a mass ratio of 1:0.85:0.2:0.0006” is changed to “1,4-butanediol, succinic acid, itaconic acid and zirconium acetylacetonate are mixed evenly in a nitrogen atmosphere at a mass ratio of 1:0.85:0.25:0.0006”.

[0050] Comparative Example 4:

[0051] The only difference from Example 2 is the step (1), where “1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate are mixed evenly in a nitrogen atmosphere at a mass ratio of 1:0.85:0.2:0.0006” is changed to “1,4-butanediol, succinic acid, itaconic acid and zirconium acetylacetonate are mixed evenly in a nitrogen atmosphere at a mass ratio of 1:0.85:0.3:0.0006”.

[0052] Comparative Example 5:

[0053] The only difference from Example 2 is step (1), where “adding 0.003 times the mass of 1,4-butanediol in tetrabutyl titanate” is changed to “adding 0.001 times the mass of 1,4-butanediol in tetrabutyl titanate”.

[0054] Comparative Example 6:

[0055] The only difference from Example 2 is step (1), where “adding 0.003 times the mass of 1,4-butanediol in tetrabutyl titanate” is changed to “adding 0.002 times the mass of 1,4-butanediol in tetrabutyl titanate”.

[0056] Comparative Example 7:

[0057] The only difference from Example 2 is step (1), where “adding 0.003 times the mass of 1,4-butanediol in tetrabutyl titanate” is changed to “adding 0.004 times the mass of 1,4-butanediol in tetrabutyl titanate”.

[0058] Comparative Example 8:

[0059] The only difference from Example 2 is step (1), where “adding 0.003 times the mass of 1,4-butanediol in tetrabutyl titanate” is changed to “adding 0.005 times the mass of 1,4-butanediol in tetrabutyl titanate”.

[0060] Comparative Example 9:

[0061] The only difference from Example 2 is the difference in step (1). In step (1), "add 0.003 times the mass of 1,4-butanediol to tetrabutyl titanate, heat to 200°C, and continue to react under vacuum for 4 hours to obtain double bond functionalized polybutylene succinate-itaconic acid block copolymer", the "heat to 200°C" is changed to "heat to 180°C".

[0062] Comparative Example 10:

[0063] The only difference from Example 2 is step (1), where “heating to 200°C” is changed to “heating to 190°C”.

[0064] Comparative Example 11:

[0065] The only difference from Example 2 is step (1), where “heating to 200°C” is changed to “heating to 210°C”.

[0066] Comparative Example 12:

[0067] The only difference from Example 2 is step (1), where “heating to 200°C” is changed to “heating to 220°C”.

[0068] Comparative Example 13:

[0069] The only difference from Example 2 is the difference in step (1). In step (1), "add 0.003 times the mass of 1,4-butanediol to tetrabutyl titanate, heat to 200°C, and continue to react under vacuum for 4 hours to obtain double bond functionalized polybutylene succinate-itaconic acid block copolymer", and "continue to react under vacuum for 4 hours" is changed to "continue to react under vacuum for 2 hours".

[0070] Comparative Example 14:

[0071] The only difference from Example 2 is step (1), which changes "continue the reaction under vacuum for 4 hours" to "continue the reaction under vacuum for 3 hours".

[0072] Comparative Example 15:

[0073] The only difference from Example 2 is step (1), which changes "continue the reaction under vacuum for 4 hours" to "continue the reaction under vacuum for 5 hours".

[0074] Comparative Example 16:

[0075] The only difference from Example 2 is the step (1), which changes "continue the reaction under vacuum for 4 hours" to "continue the reaction under vacuum for 6 hours".

[0076] Comparative Example 17:

[0077] The only difference from Example 2 is the step (3), which changes "mixing the insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone in a mass ratio of 1:0.3:11" to "mixing the insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone in a mass ratio of 1:0.1:11".

[0078] Comparative Example 18:

[0079] The only difference from Example 2 is the step (3), which changes "mixing the insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone in a mass ratio of 1:0.3:11" to "mixing the insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone in a mass ratio of 1:0.2:11".

[0080] Comparative Example 19:

[0081] The only difference from Example 2 is the step (3), which changes "mixing the insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone in a mass ratio of 1:0.3:11" to "mixing the insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone in a mass ratio of 1:0.4:11".

[0082] Comparative Example 20:

[0083] The only difference from Example 2 is the step (3), which changes "mixing the insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone in a mass ratio of 1:0.3:11" to "mixing the insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone in a mass ratio of 1:0.5:11".

[0084] Comparative Example 21:

[0085] The only difference from Example 2 is the difference in step (3). In step (3), "mixing the insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone in a mass ratio of 1:0.3:11, stirring at 300 r / min for 1 h, and drying at 70°C for 18 h to obtain surface-modified insecticide-loaded bio-based carbon black powder" is changed from "stirring at 300 r / min for 1 h" to "stirring at 300 r / min for 0.5 h".

[0086] Comparative Example 22:

[0087] The only difference from Example 2 is step (3), where “stirring at 300 r / min for 1 h” is changed to “stirring at 300 r / min for 1.5 h”.

[0088] Comparative Example 23:

[0089] The only difference from Example 2 is the difference in step (4). The phrase "mixing double-bond functionalized polybutylene succinate-itaconic acid block copolymer, modified starch, surface-modified loaded insecticide bio-based carbon black powder and glycerin in a mass ratio of 1:0.35:0.1:0.1 and then adding it to the twin-screw extruder" is changed to "mixing double-bond functionalized polybutylene succinate-itaconic acid block copolymer, modified starch, surface-modified loaded insecticide bio-based carbon black powder and glycerin in a mass ratio of 1:0.25:0.1:0.1 and then adding it to the twin-screw extruder".

[0090] Comparative Example 24:

[0091] The only difference from Example 2 is the difference in step (4). The phrase "mixing double-bond functionalized polybutylene succinate-itaconic acid block copolymer, modified starch, surface-modified loaded insecticide bio-based carbon black powder and glycerin in a mass ratio of 1:0.35:0.1:0.1 and then adding it to the twin-screw extruder" is changed to "mixing double-bond functionalized polybutylene succinate-itaconic acid block copolymer, modified starch, surface-modified loaded insecticide bio-based carbon black powder and glycerin in a mass ratio of 1:0.45:0.1:0.1 and then adding it to the twin-screw extruder".

[0092] Comparative Example 25:

[0093] A method for preparing black plastic film for rice cultivation mainly includes the following preparation steps:

[0094] (1) In a nitrogen atmosphere, 1,4-butanediol, succinic anhydride and zirconium acetylacetonate were mixed evenly at a mass ratio of 1:0.85:0.0006 and stirred at 150°C and 300 r / min for 4 h to obtain polybutylene succinate.

[0095] (2) Mix starch and anhydrous pyridine at a mass ratio of 1:10, treat with ultrasonic power of 350W for 30min to form a uniform starch suspension, add octenyl succinic anhydride at a mass of 5.5% of the dry weight of starch, stir at 35℃ and 300r / min for 8h, centrifuge, wash with deionized water and acetone three times in sequence, dry, and obtain modified starch;

[0096] (3) The corn stalks were dried at 105°C for 22 hours, ground, and then placed in a heating reactor. The mixture was pyrolyzed at 650°C for 2 hours, ground again, and passed through 200-mesh and 325-mesh standard sieves. The material passing through the 325-mesh sieve was collected to obtain corn stalk biochar black powder with a particle size of 40 μm. The corn stalk biochar black powder was soaked in 10% sulfuric acid for 7 hours, washed until neutral, and dried to obtain pretreated biochar black powder. The pretreated biochar black powder was then immersed in 3.5... A % abamectin acetone solution was treated with ultrasound at 350W for 30 min to form a uniform suspension. The suspension was then vacuum impregnated for 4 h, filtered, washed twice with acetone, and dried under vacuum in the dark to obtain insecticide-loaded carbon black powder. The insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane, and acetone were mixed uniformly at a mass ratio of 1:0.3:11, stirred at 300 r / min for 1 h, and dried at 70°C for 18 h to obtain surface-modified insecticide-loaded bio-based carbon black powder.

[0097] (4) Polybutylene succinate, modified starch, surface-modified insecticide-loaded bio-based carbon black powder and glycerin are mixed evenly in a mass ratio of 1:0.35:0.1:0.1 and then added to a twin-screw extruder. The barrel temperature from the feeding zone to the die zone is set to 105, 115, 130, 140, 130 and 100℃, and the screw speed is set to 170rpm. The extrudate is cut into granules after air cooling. The obtained granules are fed into a blown film machine. The melt is extruded at a screw speed of 50r / min under the temperature settings of 150℃ in the feeding section, 170℃ in the compression section and 190℃ in the melting section. The blown film is blown, cooled and pulled at a blown ratio of 3.0 and a traction speed of 25m / min. Finally, the black mulch film for rice cultivation is rolled up.

[0098] Comparative Example 26:

[0099] A method for preparing black plastic film for rice cultivation mainly includes the following preparation steps:

[0100] (1) In a nitrogen atmosphere, 1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate were mixed evenly in a mass ratio of 1:0.85:0.2:0.0006 and stirred at 150°C and 300 r / min for 2 h. Then, 0.003 times the mass of 1,4-butanediol was added to tetrabutyl titanate, the temperature was raised to 200°C, and the reaction was continued under vacuum for 4 h to obtain double bond functionalized polybutylene succinate-itaconic acid block copolymer;

[0101] (2) Corn stalks were dried at 105°C for 22 hours, ground, and then placed in a heating reactor. The mixture was pyrolyzed at 650°C for 2 hours, ground again, and passed through 200-mesh and 325-mesh standard sieves. The material passing through the 325-mesh sieve was collected to obtain corn stalk biochar black powder with a particle size of 40 μm. The corn stalk biochar black powder was soaked in 10% sulfuric acid for 7 hours, washed until neutral, and dried to obtain pretreated biochar black powder. The pretreated biochar black powder was then immersed in 3.5... A % abamectin acetone solution was treated with ultrasound at 350W for 30 min to form a uniform suspension. The suspension was then vacuum impregnated for 4 h, filtered, washed twice with acetone, and dried under vacuum in the dark to obtain insecticide-loaded carbon black powder. The insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane, and acetone were mixed uniformly at a mass ratio of 1:0.3:11, stirred at 300 r / min for 1 h, and dried at 70°C for 18 h to obtain surface-modified insecticide-loaded bio-based carbon black powder.

[0102] (3) The double bond functionalized polybutylene succinate-itaconic acid block copolymer, surface modified loaded insecticide bio-based carbon black powder and glycerin were mixed evenly at a mass ratio of 1:0.1:0.1 and then added to a twin-screw extruder. The barrel temperature from the feeding zone to the die zone was set to 105, 115, 130, 140, 130 and 100℃, and the screw speed was set to 170rpm. The extrudate was air-cooled and cut into granules. The obtained granules were fed into a blown film machine. The melt was extruded at a screw speed of 50r / min under the temperature settings of 150℃ in the feeding section, 170℃ in the compression section and 190℃ in the melting section. The blown film was blown, cooled and pulled at a blown ratio of 3.0 and a traction speed of 25m / min. Finally, the black mulch film for rice cultivation was rolled up.

[0103] Comparative Example 27:

[0104] A method for preparing black plastic film for rice cultivation mainly includes the following preparation steps:

[0105] (1) In a nitrogen atmosphere, 1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate were mixed evenly in a mass ratio of 1:0.85:0.2:0.0006 and stirred at 150°C and 300 r / min for 2 h. Then, 0.003 times the mass of 1,4-butanediol was added to tetrabutyl titanate, the temperature was raised to 200°C, and the reaction was continued under vacuum for 4 h to obtain double bond functionalized polybutylene succinate-itaconic acid block copolymer;

[0106] (2) Mix starch and anhydrous pyridine at a mass ratio of 1:10, treat with ultrasonic power of 350W for 30min to form a uniform starch suspension, add octenyl succinic anhydride at a mass of 5.5% of the dry weight of starch, stir at 35℃ and 300r / min for 8h, centrifuge, wash with deionized water and acetone three times in sequence, dry, and obtain modified starch;

[0107] (3) The corn stalks were dried at 105°C for 22 hours, ground, and then placed in a heating reactor. The stalks were pyrolyzed at 650°C for 2 hours, ground, and passed through 200 mesh and 325 mesh standard sieves in sequence. The material under the 325 mesh sieve was collected to obtain corn stalk bio-carbon black powder with a particle size of 40 μm. The bio-carbon black powder was immersed in 3.5% abamectin acetone solution and treated under ultrasonic power of 350W for 30 minutes to form a uniform suspension. The suspension was vacuum impregnated for 4 hours, filtered, washed twice with acetone, and dried under vacuum in the dark to obtain insecticide-loaded carbon black powder.

[0108] (4) The double-bond functionalized polybutylene succinate-itaconic acid block copolymer, modified starch, insecticide-loaded bio-based carbon black powder and glycerin were mixed evenly in a mass ratio of 1:0.35:0.1:0.1 and then added to a twin-screw extruder. The barrel temperature from the feeding zone to the die zone was set to 105, 115, 130, 140, 130 and 100℃, and the screw speed was set to 170rpm. The extrudate was air-cooled and cut into granules. The resulting granules were fed into a blown film machine. The melt was extruded at a screw speed of 50r / min under the temperature settings of 150℃ in the feeding section, 170℃ in the compression section and 190℃ in the melting section. The blown film was blown, cooled and pulled at a blown ratio of 3.0 and a traction speed of 25m / min. Finally, the black mulch film for rice cultivation was produced by winding.

[0109] Comparative Example 28:

[0110] A method for preparing black plastic film for rice cultivation mainly includes the following preparation steps:

[0111] (1) In a nitrogen atmosphere, 1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate were mixed evenly in a mass ratio of 1:0.85:0.2:0.0006 and stirred at 150°C and 300 r / min for 2 h. Then, 0.003 times the mass of 1,4-butanediol was added to tetrabutyl titanate, the temperature was raised to 200°C, and the reaction was continued under vacuum for 4 h to obtain double bond functionalized polybutylene succinate-itaconic acid block copolymer;

[0112] (2) Mix starch and anhydrous pyridine at a mass ratio of 1:10, treat with ultrasonic power of 350W for 30min to form a uniform starch suspension, add octenyl succinic anhydride at a mass of 5.5% of the dry weight of starch, stir at 35℃ and 300r / min for 8h, centrifuge, wash with deionized water and acetone three times in sequence, dry, and obtain modified starch;

[0113] (3) The corn stalks were dried at 105°C for 22 hours, ground, and then placed in a heating reactor. The stalks were pyrolyzed at 650°C for 2 hours, ground, and passed through 200 mesh and 325 mesh standard sieves. The material under the 325 mesh sieve was collected to obtain corn stalk bio-carbon black powder with a particle size of 40 μm. The corn stalk bio-carbon black powder was soaked in 10% sulfuric acid for 7 hours, washed until neutral, and dried to obtain pretreated bio-carbon black powder. The pretreated bio-carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone were mixed evenly at a mass ratio of 1:0.3:11, stirred at 300 r / min for 1 hour, and dried at 70°C for 18 hours to obtain surface-modified bio-based carbon black powder.

[0114] (4) The double bond functionalized polybutylene succinate-itaconic acid block copolymer, modified starch, surface modified bio-based carbon black powder and glycerol were mixed evenly in a mass ratio of 1:0.35:0.1:0.1 and then added to a twin-screw extruder. The barrel temperature from the feeding zone to the die zone was set to 105, 115, 130, 140, 130 and 100℃, and the screw speed was set to 170rpm. The extrudate was air-cooled and cut into granules. The resulting granules were fed into a blown film machine. The melt was extruded at a screw speed of 50r / min under the temperature settings of 150℃ in the feeding section, 170℃ in the compression section and 190℃ in the melting section. The blown film was blown, cooled and pulled at a blown ratio of 3.0 and a traction speed of 25m / min. Finally, the black mulch film for rice cultivation was produced by winding.

[0115] Experimental Example 1:

[0116] Determination of optimal conditions for double-bond functionalized polybutylene succinate-itaconic acid block copolymer (itaconic acid addition amount, titanate addition amount, reaction temperature, and reaction time).

[0117] Test method: Analysis was performed by iodine titration based on the double bond content. 0.5 g of the double-bond functionalized polybutylene succinate-itaconic acid block copolymer sample was dissolved in 20 mL of tetrahydrofuran, and 30 mL of Widmanstätten reagent was added. The mixture was reacted at 25 °C in the dark for 1 h. Then, 20 mL of 10% potassium iodide solution was added, and the mixture was shaken well and allowed to stand for 5 min. The flask wall was rinsed with 100 mL of distilled water, and the solution turned reddish-brown. Titration with 0.1 mol / L sodium thiosulfate was performed until a pale yellow color was obtained. 2 mL of starch indicator was added, and titration continued until the blue color disappeared. The titration volume V1 was recorded. The reagent system without the sample was treated in the same way, and V0 was recorded. The results are shown in Table 1.

[0118] Double bond density = (mmol / g);

[0119] C represents the concentration of sodium thiosulfate (mol / L);

[0120] M represents the molecular weight of iodine (126.9 g / mol).

[0121] m represents the sample mass.

[0122] Table 1 Itaconic acid / 1,4-butanediol (mass ratio) Butyl titanate / 1,4-butanediol (mass ratio) reaction temperature reaction time Double bond density Example 2 0.2 0.003 200℃ 4h 0.281mmol / g Comparative Example 1 0.1 0.003 200℃ 4h 0.159mmol / g Comparative Example 2 0.15 0.003 200℃ 4h 0.192mmol / g Comparative Example 3 0.25 0.003 200℃ 4h 0.275mmol / g Comparative Example 4 0.3 0.003 200℃ 4h 0.214mmol / g Comparative Example 5 0.2 0.001 200℃ 4h 0.173mmol / g Comparative Example 6 0.2 0.002 200℃ 4h 0.226mmol / g Comparative Example 7 0.2 0.004 200℃ 4h 0.235mmol / g Comparative Example 8 0.2 0.005 200℃ 4h 0.199mmol / g Comparative Example 9 0.2 0.003 180℃ 4h 0.156mmol / g Comparative Example 10 0.2 0.003 190℃ 4h 0.248mmol / g Comparative Example 11 0.2 0.003 210℃ 4h 0.256mmol / g Comparative Example 12 0.2 0.003 220℃ 4h 0.203mmol / g Comparative Example 13 0.2 0.003 200℃ 2h 0.178mmol / g Comparative Example 14 0.2 0.003 200℃ 3h 0.242mmol / g Comparative Example 15 0.2 0.003 200℃ 5h 0.279mmol / g Comparative Example 16 0.2 0.003 200℃ 6h 0.261mmol / g

[0123] A comparison of Example 2 and Comparative Examples 1-4 reveals that itaconic acid is the source of double bonds in the copolymer, and its addition amount significantly affects the double bond density. When the amount of itaconic acid added is too low, the source of double bonds is insufficient, resulting in a low proportion of itaconic acid units in the copolymer and an inability to provide sufficient crosslinking sites. When the amount of itaconic acid added is too high, excess itaconic acid leads to the formation of homopolymers, reducing the molecular weight, while also causing double bond isomerization and conjugation deactivation. Therefore, experiments determined that the optimal addition amount of itaconic acid is 0.2 times the amount of 1,4-butanediol.

[0124] A comparison of Examples 2 and Comparative Examples 5-8 reveals that the amount of n-butyl titanate added as a catalyst for polycondensation significantly affects the double bond density in the copolymer. When the amount of n-butyl titanate added is low, the catalytic efficiency is insufficient, the degree of polycondensation is low, the molecular chain is short, and the introduced double bond density is low. When the amount of n-butyl titanate added is excessive, the excess titanium ions lead to the decarboxylation of itaconic acid and trigger oxidative crosslinking of the double bonds. Therefore, experiments determined that the optimal amount of n-butyl titanate added is 0.003 times that of 1,4-butanediol.

[0125] A comparison of Example 2 and Comparative Examples 9-12 reveals that the reaction temperature affects the double bond density of the copolymer. Insufficient temperature leads to excessively high viscosity in the reaction system, hindering water removal and resulting in insufficient polymerization. Excessively high temperature causes decarboxylation of itaconic acid and cycloaddition of the double bonds, leading to a loss of double bond density. Therefore, the optimal reaction temperature is controlled at 200°C.

[0126] Comparisons between Example 2 and Comparative Examples 9-12 revealed that the double bond density stabilized at 0.281 mmol / g when the reaction time was 4 h. When the reaction time was less than 3 h, the terminal carboxyl group capping rate was insufficient, and unreacted carboxyl groups competed with the double bond to consume the titanium catalyst, resulting in a decrease in double bond density. After 5 h, the reverse hydrolysis reaction intensified, and the free radicals generated from ester bond breakage attacked the double bond, initiating isomerization and further reducing the effective double bond density. Therefore, the optimal reaction time was determined experimentally to be 4 h.

[0127] Therefore, the optimal selection was chosen as the following: itaconic acid addition amount was 0.2 times that of 1,4-butanediol addition amount, n-butyl ester addition amount was 0.003 times that of 1,4-butanediol addition amount, reaction temperature was 200℃, and reaction time was 4h, which are the reaction conditions of Example 2.

[0128] Experimental Example 2:

[0129] Determination of optimal modification conditions for surface-modified insecticide-loaded bio-based carbon black powder (addition amount of 3-mercaptopropyltrimethoxysilane, reaction time).

[0130] Test method: The tensile strength, toughness, and Young's modulus of black plastic mulch film used for rice cultivation were determined by mechanical properties according to the international standard ISO 1184-1983 "Determination of tensile properties of plastic films". The tensile speed was 2 mm / min. The results are shown in Table 2.

[0131] Table 2 3-Mercaptopropyltrimethoxysilane / carbon black powder (mass ratio) reaction time Tensile strength toughness Young's modulus Example 2 0.3 1h 69.6MPa <![CDATA[5.5MJ / m 3 ]]> 4.9 GPa Comparative Example 17 0.1 1h 38.8MPa <![CDATA[4.0MJ / m 3 ]]> 2.2 GPa Comparative Example 18 0.2 1h 49.3MPa <![CDATA[4.4MJ / m 3 ]]> 3.3 GPa Comparative Example 19 0.4 1h 57.3MPa <![CDATA[5.1MJ / m 3 ]]> 3.8GPa Comparative Example 20 0.5 1h 46.2MPa <![CDATA[4.2MJ / m 3 ]]> 3.1 GPa Comparative Example 21 0.3 0.5h 39.5MPa <![CDATA[4.1MJ / m 3 ]]> 2.4 GPa Comparative Example 22 0.3 1.5h 69.1MPa <![CDATA[5.3MJ / m 3 ]]> 4.8 GPa

[0132] A comparison of Example 2 and Comparative Examples 17-20 reveals that when the amount of 3-mercaptopropyltrimethoxysilane added is 0.3 times the mass of carbon black, the tensile strength of the mulch film reaches a peak of 68.6 MPa, and the maximum toughness reaches 5.5 MJ / m. 3 The Young's modulus remained stable at 4.9 GPa. When the silane addition was too low, the surface thiol density of the carbon black was insufficient, resulting in a low conversion rate of the thiol-olefin click reaction with the polyester double bond during melt blending. Weak interfacial chemical bonding also reduced stress transfer efficiency. When the addition was too high, the agglomerated silane hindered carbon black dispersion, leading to stress concentration points in the mulch film and a decrease in mechanical properties. Therefore, experiments determined the optimal addition amount of 3-mercaptopropyltrimethoxysilane to be 0.3 times the mass of carbon black.

[0133] A comparison of Example 2 and Comparative Examples 17-20 reveals that the mechanical properties are optimal when the reaction time is 1 hour. Insufficient reaction time leads to incomplete silane hydrolysis, resulting in a lack of covalent crosslinking networks at the carbon black-polyester interface. Further increasing the reaction time does not significantly improve the mechanical properties. Therefore, considering experimental efficiency, the reaction time should be controlled at 1 hour.

[0134] Therefore, the optimal selection was to add 0.3 times the mass of carbon black to 3-mercaptopropyltrimethoxysilane and to react for 1 hour, which are the reaction conditions in Example 2.

[0135] Experimental Example 3:

[0136] Determining the optimal amount of modified starch to be added.

[0137] Test Method: For biodegradability testing, 20mm × 20mm thin sheets of black plastic mulch used for rice cultivation were molded and cut as samples. These samples were buried 5cm below the surface of the natural soil. Samples were taken after 120 days to monitor biodegradation. The degradation rate was calculated as 1 - (mass after 120 days / initial mass). The results are shown in Table 3.

[0138] Table 3 Modified starch / polybutylene succinate-itaconic acid block copolymer (mass ratio) Degradation rate Comparative Example 23 0.25 43.2% Example 2 0.35 75.9% Comparative Example 24 0.45 90.1%

[0139] Comparisons between Example 2 and Comparative Examples 23-24 revealed that when the modified starch content was 0.35 times the mass of the polybutylene succinate-itaconic acid block copolymer, the degradation rate of the mulch film was 75.9% after 120 days, and it completely disintegrated within 60 days after harvest. When the starch content was low, the starch phase proportion was insufficient, resulting in scarce microbial colonization sites and a decreased degradation rate; conversely, excessive starch content led to water absorption and swelling, disrupting the continuous polyester phase and causing excessively rapid degradation, which could not match the rice growth cycle. Therefore, experiments determined the optimal modified starch content to be 0.35 times the mass of the polybutylene succinate-itaconic acid block copolymer.

[0140] Test Example 4

[0141] Tests on biodegradability, tensile strength, and insect repellency.

[0142] Biodegradability testing method: The black mulch film for rice cultivation obtained in each example and the mulch film of comparative examples 25-28 were molded and cut into 20mm×20mm thin sheets as samples, buried 5cm below the surface of natural soil, and samples were taken after 120 days to monitor biodegradation. The degradation rate was calculated as 1 - (mass after 120 days / initial mass).

[0143] Tensile strength test method: The tensile strength of the black mulch film for rice cultivation obtained in each example and the mulch film of comparative examples 25~28 were tested according to the international standard ISO 1184-1983 "Determination of tensile properties of plastic films" with a tensile speed of 2 mm / min.

[0144] Insect repellency performance test method: The insect repellency performance of the plastic film was determined using the regional preference method. The black plastic film for rice cultivation obtained in each example and the 25-28 plastic film of the comparative examples were cut into semicircles. Half a sheet of the test film and half a sheet of pure polyester film were placed in a petri dish, respectively. 1 g of dried shrimp paste was placed in the center of each petri dish as bait. Ten adult houseflies were introduced into each dish, and the distribution and number of insects in the sample half and control half were recorded after 3 hours. The repellency rate was calculated using the following formula:

[0145] Avoidance rate (%) = [(Nc-Ns) / Nt] × 100%;

[0146] Nc represents the number of insects in the control half-region;

[0147] Ns represents the number of insects in the sample half-region;

[0148] Nt represents the total number of insects;

[0149] The results are shown in Table 4.

[0150] Table 4 Degradation rate Tensile strength Avoidance rate Example 1 75.3% 69.3MPa 63.9% Example 2 75.9% 69.6MPa 64.5% Example 3 76.1% 69.5MPa 64.1% Comparative Example 25 74.9% 30.2MPa 58.4% Comparative Example 26 36.7% 59.9MPa 60.3% Comparative Example 27 73.8% 42.8MPa 59.6% Comparative Example 28 75.0% 67.6MPa 18.8%

[0151] A comparison of the experimental data from Examples 1-3 and Comparative Examples 25-28 in Table 4 reveals that the black mulch film for rice cultivation prepared by this invention has good biodegradability, tensile strength, and insect repellency.

[0152] By comparing Examples 1-3 and Comparative Example 25, it can be found that when itaconic acid is added during the preparation of polybutylene succinate, the unsaturated double bonds of itaconic acid provide key reaction sites for the mercapto-thiol click chemistry of the thiol group on the carbon black surface, forming a polyester-carbon black covalent crosslinking network, thereby improving the tensile strength. Without the addition of itaconic acid, the carbon black particles exist in the form of physical filling, becoming stress concentration defect points, and the tensile strength is reduced.

[0153] By comparing Examples 1-3 and Comparative Example 26, it can be found that adding modified starch during the preparation of black mulch for rice cultivation can significantly improve its biodegradability.

[0154] By comparing Examples 1-3 and Comparative Example 27, it can be found that surface modification of the insecticide-loaded carbon black powder with 3-mercaptopropyltrimethoxysilane to introduce thiol groups, which undergo thiol-ene click chemistry with the unsaturated double bonds of itaconic acid during subsequent melt blending, forming a polyester-carbon black covalent crosslinking network, which significantly improves tensile strength.

[0155] By comparing Examples 1-3 and Comparative Example 28, it can be found that loading abamectin with biochar black powder can significantly improve the insect repellent performance during the preparation of black mulch for rice cultivation.

Claims

1. A black plastic mulch film for rice cultivation, characterized in that, The black mulch film for rice cultivation is made by mixing polybutylene succinate-itaconic acid block copolymer, modified starch, and surface-modified drug-loaded bio-based carbon black powder, followed by granulation and blow molding.

2. The black mulch film for rice cultivation according to claim 1, characterized in that, The polybutylene succinate-itaconic acid block copolymer is prepared by vacuum polycondensation of 1,4-butanediol, succinic anhydride and itaconic acid.

3. The black mulch film for rice cultivation according to claim 1, characterized in that, The modified starch is prepared by esterification reaction of starch with octenyl succinic anhydride.

4. The black mulch film for rice cultivation according to claim 1, characterized in that, The surface-modified drug-loaded bio-based carbon black powder is prepared by pyrolysis of corn stalks to produce bio-carbon black, which is then acid-washed and activated, loaded with avermectin, and then surface-modified with 3-mercaptopropyltrimethoxysilane.

5. A method for preparing black plastic film for rice cultivation, characterized in that, The preparation steps include the following: (1) In a nitrogen atmosphere, 1,4-butanediol, succinic anhydride, itaconic acid and zirconium acetylacetonate were mixed evenly in a mass ratio of 1:(0.75~0.95):(0.1~0.3):(0.0004~0.0008) and stirred at 130~170℃ and 200~400r / min for 1~3h. Then, 0.001~0.005 times the mass of 1,4-butanediol was added to tetrabutyl titanate, and the temperature was raised to 180~220℃. The reaction was continued under vacuum for 2~6h to obtain double bond functionalized polybutylene succinate-itaconic acid block copolymer. (2) Mix starch and anhydrous pyridine at a mass ratio of 1:8~12, treat with ultrasonic power of 200~500W for 20~40min to form a uniform starch suspension, add octenyl succinic anhydride at a mass of 3%~8% of the dry weight of starch, stir at 25~45℃ and 200~400r / min for 6~10h, centrifuge, wash with deionized water and acetone 2~3 times in sequence, dry, and obtain modified starch; (3) Soak corn stalk bio-carbon black powder in 8%~12% sulfuric acid for 6~8h, wash until neutral, dry to obtain pretreated bio-carbon black powder; Soak the pretreated bio-carbon black powder in 2%~5% abamectin acetone solution, treat under ultrasonic power of 200~500W for 20~40min to form a uniform suspension, vacuum impregnate for 2~6h, filter, wash with acetone 1~3 times, vacuum dry in the dark to obtain insecticide-loaded carbon black powder; Mix insecticide-loaded carbon black powder, 3-mercaptopropyltrimethoxysilane and acetone at a mass ratio of 1:(0.1~0.5):(10~12) evenly, stir at 200~400r / min for 0.5~1.5h, dry at 60~80°C for 12~24h to obtain surface-modified insecticide-loaded bio-based carbon black powder; (4) The double-bond functionalized polybutylene succinate-itaconic acid block copolymer, modified starch, surface-modified loaded insecticide bio-based carbon black powder and glycerin are mixed evenly at a mass ratio of 1:(0.25~0.45):(0.08~0.12):(0.05~0.15) and then added to a twin-screw extruder. The barrel temperature from the feeding zone to the die zone is set to 105, 115, 130, 140, 130 and 100℃, and the screw speed is set to 160~180rpm. The extrudate is cut into granules after air cooling. The obtained granules are fed into a blown film machine to blow film and obtain black mulch for rice cultivation.

6. The method for preparing a black mulch film for rice cultivation according to claim 5, characterized in that, The reaction process of the double-bond functionalized polybutylene succinate-itaconic acid block copolymer in step (1) is as follows: 。 7. The method for preparing a black mulch film for rice cultivation according to claim 5, characterized in that, The starch mentioned in step (2) is cassava starch with a straight-chain starch content of 25%.

8. A method for preparing black plastic film for rice cultivation according to claim 5, characterized in that, The corn stalks mentioned in step (3) were collected from local farms in Sichuan, China.

9. A method for preparing a black mulch film for rice cultivation according to claim 5, characterized in that, The preparation method of the corn stalk bio-carbon black powder in step (3) is as follows: the corn stalk is dried at 95~115°C for 18~24h, ground, and then the ground corn stalk is placed in a heating reactor and pyrolyzed at 500~800°C for 1~3h. After grinding, the powder is passed through a 200 mesh and a 325 mesh standard sieve in sequence, and the material under the 325 mesh sieve is collected to obtain corn stalk bio-carbon black powder with a particle size of 35~45μm.

10. A method for preparing a black plastic film for rice cultivation according to claim 5, characterized in that, The method for blowing black plastic film for rice cultivation described in step (4) is as follows: The obtained granules are fed into a blown film machine. Under the temperature settings of 140~160℃ in the feeding section, 160~180℃ in the compression section, and 180~200℃ in the melting section, the melt is extruded at a screw speed of 30~70r / min. The film is blown, cooled, and pulled at a blowing ratio of 2.0~3.0 and a traction speed of 15~30m / min. Finally, the film is rolled up to obtain black plastic film for rice cultivation.

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