Preparation method of rice seed dressing agent and product thereof

Abstract

The invention provides a preparation method of a rice seed-dressing agent and a product thereof. According to the method, the emulsifying dispersity and the storage stability of the redissolved seed dressing agent are improved through sulfonated polyester; the drug slow release performance of the seed dressing agent is improved through sulfonated polyester, ethylene-vinyl acetate copolymer and interfacial polymerization reaction; by adding partially hydrolyzed polyvinyl acetate and a ternary acrylic acid copolymer, the shedding rate of the seed dressing agent is reduced; by using zeolite, humic acid and copper hydroxide, the copper ion slow release capability of the seed dressing agent is improved.

Description

Technical Field

[0001] The invention relates to the technical field of seed dressing agents, and in particular to a preparation method of a rice seed dressing agent and a product thereof. Background Art

[0002] Rice is my country's staple food crop and plays a vital role in agricultural production. Soil-borne and seed-borne diseases of rice during the seedling stage, as well as infestations by pests in the lower and upper soil, affect rice yield and quality. Common rice pests include rice planthoppers, thrips, rice leaf rollers, stem borers, and striped stem borers. Rice seed dressing agents can effectively prevent and control early pests and control the spread of rice diseases. The seed dressing agent is coated on the surface of rice seeds. When the seeds come into contact with water, the active ingredients form a barrier around the seeds, preventing infection by soil-borne pathogens and damage from soil pests, and can kill pathogens and pests hidden in the seeds. As the seeds germinate and become seedlings, the active substances are slowly released from the roots and are internally absorbed and conducted to the aboveground part of the plant, where they continue to promote growth and protect against insects and diseases.

[0003] Sustained-release performance is a key quality indicator for seed dressings. Sustained-release can extend the protection period; it can also control the release rate to reduce the risk of pesticide damage, reduce application frequency, and improve drug utilization. However, existing sustained-release carriers, such as ethyl cellulose, have poor environmental adaptability and a high initial burst release rate, making them unable to meet the full growth period requirements of crop seedlings.

[0004] According to literature reports, copper ions (Cu ) can be used as a key active ingredient in seed dressings, exerting its bactericidal effect by destroying pathogen cell membranes, interfering with enzyme systems, and inducing reactive oxygen species (ROS) bursts. However, existing copper preparations (such as copper sulfate or copper chloride) are too soluble and have a high initial release rate of copper ions, making a sustained supply impossible.

[0005] Another quality indicator of seed dressing agents is the shedding rate. Insufficient seed adhesion can lead to shedding and loss during transportation and sowing, resulting in waste of the active ingredients. Prior art methods have primarily used binders such as carboxymethyl cellulose to reduce shedding rates. However, carboxymethyl cellulose is highly hydrophilic, resulting in a brittle film after drying. This also hinders the air permeability of the seed dressing layer, impacting the biological activity of the seeds.

[0006] Emulsification and dispersibility are also important quality indicators for seed dressing agents. Excellent emulsification and dispersibility improve coating uniformity, allowing the solution to form a continuous film on the seed surface. It also enhances agent stability, preventing stratification of active ingredients, which directly affects the uniformity of the seed dressing and, in turn, the preventive efficacy of the seed dressing. Existing methods for improving emulsification and dispersibility primarily use surfactants, such as alkylphenol polyoxyethylene ethers, to form stable emulsions. However, mixing alkylphenol polyoxyethylene ethers with copper preparations produces blue floccules, limiting their use in copper-containing seed dressings. Summary of the Invention

[0007] In order to solve the above problems, the first aspect of the present invention provides a method for preparing a rice seed dressing agent, comprising the following steps: Step S1, preparing sulfonated polyester: adding adipic acid, dimethyl terephthalate and sodium 5-sulfoisophthalate to a reactor, and carrying out an ester exchange reaction with excess 1,4-butanediol under nitrogen protection; then carrying out a polycondensation reaction to obtain sulfonated polyester; dissolving the sulfonated polyester and sodium dodecylbenzenesulfonate in dichloromethane to prepare oil phase A; Step S2, adding ethylene-vinyl acetate copolymer: dissolving ethylene-vinyl acetate copolymer in oil phase A to prepare oil phase B; Step S3, active ingredient loading: dispersing the active ingredient in oil phase B to prepare oil phase C; Step S4, adding diphenylmethane diisocyanate: dissolving diphenylmethane diisocyanate in the oil phase C to prepare the oil phase D; Step S5, preparing a ternary acrylic acid copolymer solution: dissolving the ternary acrylic acid copolymer and sodium dodecylbenzenesulfonate in ethyl acetate to prepare a ternary acrylic acid copolymer solution E; Step S6, partially hydrolyzing polyvinyl acetate: dissolving polyvinyl acetate in methanol to prepare solution F; adding sodium hydroxide to solution F to carry out a hydrolysis reaction; adjusting the pH with acetic acid to terminate the reaction; adding excess acetone to collect the precipitate; filtering the precipitate, washing with deionized water, and vacuum drying to prepare partially hydrolyzed polyvinyl acetate; dispersing the partially hydrolyzed polyvinyl acetate in ternary acrylic acid copolymer solution E to prepare solution G; Step S7, aqueous phase preparation: dissolving sucrose ester and sodium dioctyl sulfosuccinate in deionized water, and adjusting the pH to 6.8-7.2 with sodium hydroxide to prepare aqueous phase H; Step S8, chelating copper ions with zeolite: dispersing zeolite and copper hydroxide in aqueous phase H to form aqueous phase I; Step S9, adding humic acid: dispersing humic acid in aqueous phase I to form aqueous phase J; Step S10, adding ethylenediamine: dispersing ethylenediamine in aqueous phase J to form aqueous phase K; Step S11, gradient emulsification-interfacial polymerization reaction: adding the oil phase D and solution G to the aqueous phase K, homogenizing, and performing emulsification-interfacial polymerization reaction to prepare a crude emulsion L; Step S12, high-pressure homogenization: adding sodium chloride to the crude emulsion L and homogenizing under high pressure to prepare emulsion M; Step S13, drying: the emulsion M is dried to prepare a seed dressing agent.

[0008] As a preferred technical solution, in step S1, the transesterification reaction temperature is 150°C to 180°C, and the reaction time is 2 hours to 3 hours; the polycondensation reaction temperature is 200°C to 220°C, and the reaction time is 4 hours to 6 hours; the vacuum degree of the polycondensation reaction is <10 mbar; the viscosity of the sulfonated polyester is 0.7 dL / g to 0.9 dL / g; the molar ratio of adipic acid, dimethyl terephthalate, sodium 5-sulfoisophthalate, and 1,4-butanediol is 100:100:(0.4-1):(240-260); and the mass ratio of the sulfonated polyester, dichloromethane, and sodium dodecylbenzenesulfonate is 1:(12-15):(0.03-0.05).

[0009] As a preferred technical solution, the mass ratio of ethylene-vinyl acetate copolymer to oil phase A in step S2 is 1:(10-15); the mass fraction of vinyl acetate homopolymer in the ethylene-vinyl acetate copolymer is 25%-30%; the dissolution temperature is 70°C-80°C, and the dissolution time is 1 hour-2 hours.

[0010] As a preferred technical solution, the mass ratio of the active ingredient to the oil phase B in step S3 is 1:(30-40); the dispersion method is ultrasonic dispersion, the ultrasonic dispersion frequency is 20 kHz, and the time is 30 minutes; the particle size D50 of the oil phase C is less than 2 μm; and the active ingredient is diprofenocet.

[0011] As a preferred technical solution, the mass ratio of diphenylmethane diisocyanate to oil phase C in step S4 is 1:(20-25).

[0012] As a preferred technical solution, the particle size D50 of the ternary acrylic acid copolymer solution in step S5 is less than 500 nm; the finger-gallery ratio of the ternary acrylic acid copolymer, sodium dodecylbenzenesulfonate, and ethyl acetate is 1:(0.4-0.6):(88-92); the mass ratio of methyl methacrylate, 2-butyl acrylate, and acrylic acid in the ternary acrylic acid copolymer is 1:(1-1.2):(0.1-0.12); and the dissolution temperature is 50°C to 60°C.

[0013] As a preferred technical solution, in step S6, the mass ratio of polyvinyl acetate to methanol is 1:(5-10); the dissolution temperature is 50°C-55°C, and the dissolution time is 2 hours-3 hours; the molar ratio of sodium hydroxide to vinyl acetate units is (0.5-0.8):1, the hydrolysis reaction temperature is 60°C-70°C, and the reaction time is 3 hours-5 hours; the vacuum drying temperature is 60°C-70°C; the degree of hydrolysis of the partially hydrolyzed polyvinyl acetate is 50%-80%; the 50%-80% means that 50%-80% of the acetate groups are hydrolyzed; the mass ratio of the partially hydrolyzed polyvinyl acetate to the ternary acrylic acid copolymer solution E is 1:(15-20).

[0014] As a preferred technical solution, the mass ratio of sucrose ester, sodium dioctyl sulfosuccinate, and deionized water in step S7 is 1: (0.1-0.2): (120-140).

[0015] Sucrose esters provide steric hindrance; neutral pH maintains the optimal ionization state of the sulfonic acid groups, and the emulsion is electrostatically stabilized by the sulfonates.

[0016] As a preferred technical solution, the mass ratio of zeolite, copper hydroxide, and aqueous phase H in step S8 is 1: (0.8-1): (8-10); the zeolite particle size D50 ≤ 10 μm; and the dispersion time is 3 hours to 5 hours.

[0017] As a preferred technical solution, the mass ratio of humic acid to aqueous phase I in step S9 is 1:(19-21); the dispersion time is 3 hours to 5 hours; the humic acid is derived from natural organic peat or lignite, and the humic acid meets organic certification standards.

[0018] As a preferred technical solution, the mass ratio of ethylenediamine to the aqueous phase J in step S10 is 1:(100-120).

[0019] As an optimal technical solution, the emulsification-interfacial polymerization reaction in step S11 includes a first-stage emulsification-interfacial polymerization reaction, a second-stage emulsification-interfacial polymerization reaction, and a third-stage emulsification-interfacial polymerization reaction; during the first-stage emulsification-interfacial polymerization reaction, the mass ratio of the oil phase D, the solution G, and the aqueous phase K is 1:0.3:10; the oil phase D is continued to be added to make the mass ratio of the oil phase D and the aqueous phase K be 1:5, homogenized, and the second-stage emulsification-interfacial polymerization reaction is carried out; the oil phase D is continued to be added to make the mass ratio of the oil phase D and the aqueous phase K be 1:3.5, homogenized, and the third-stage emulsification-interfacial polymerization reaction is carried out; the homogenization speed is 18000 rpm; the emulsification-interfacial polymerization reaction time is 2 hours to 4 hours; the emulsification-interfacial polymerization reaction temperature is 50°C to 60°C; the emulsification-interfacial polymerization reaction pH is 8.5 to 9.0.

[0020] Gradient emulsification can avoid phase separation caused by local overconcentration.

[0021] As a preferred technical solution, the sodium chloride concentration in the crude emulsion L in step S12 is 5 mmol / L; and the high-pressure homogenization pressure is 700 bar.

[0022] Staged treatment can avoid emulsion flocculation caused by high pressure in one time.

[0023] As a preferred technical solution, the drying in step S13 is freeze drying; the pre-freezing temperature of the freeze drying is -30°C, and the pre-freezing time is 4 hours; the sublimation drying temperature of the freeze drying is -10°C, and the sublimation drying time is 24 hours; the sublimation drying vacuum degree is 1 mbar; the desorption drying temperature of the freeze drying is 25°C, and the desorption drying time is 6 hours; and the desorption drying vacuum degree is 0.5 mbar.

[0024] The second aspect of the present invention provides a rice seed dressing agent, which is prepared by the above-mentioned preparation method.

[0025] The third aspect of the present invention provides a method for improving the emulsification and dispersibility of a seed dressing agent after redissolution, wherein the method adopts the aforementioned method for preparing the seed dressing agent.

[0026] A fourth aspect of the present invention provides a method for improving the sustained-release performance of active ingredients in a seed dressing agent, wherein the method adopts the aforementioned method for preparing the seed dressing agent.

[0027] A fifth aspect of the present invention provides a method for improving the sustained-release performance of copper ions in a seed dressing agent, wherein the method adopts the aforementioned method for preparing the seed dressing agent.

[0028] A sixth aspect of the present invention provides a method for reducing the shedding rate of a seed dressing agent, wherein the method adopts the aforementioned method for preparing the seed dressing agent.

[0029] Through the above technical solutions, the present invention produces the following technical effects: (1) Sulfonated polyester is used to improve the emulsification, dispersibility and storage stability of seed dressing after redissolution.

[0030] (2) Improve the sustained-release performance of seed dressing by using sulfonated polyester, ethylene-vinyl acetate copolymer, and interfacial polymerization.

[0031] (3) By adding partially hydrolyzed polyvinyl acetate and ternary acrylic acid copolymer, the shedding rate of seed dressing agent is reduced.

[0032] (4) Improve the sustained release capacity of copper ions in seed dressing agents by using zeolite, humic acid and copper hydroxide. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the applicant provides illustrations and analyses through specific embodiments and comparative examples.

[0034] Example 1

[0035] Step S1, preparing sulfonated polyester: adding adipic acid, dimethyl terephthalate and sodium 5-sulfoisophthalate to a reactor, and carrying out an ester exchange reaction with excess 1,4-butanediol under nitrogen protection; then carrying out a polycondensation reaction to obtain sulfonated polyester; the ester exchange reaction temperature is 150° C., and the reaction time is 2 hours; the polycondensation reaction temperature is 200° C., and the reaction time is 4 hours; the vacuum degree of the polycondensation reaction is 3 mbar; the viscosity of the sulfonated polyester is 0.7 dL / g; the molar ratio of adipic acid, dimethyl terephthalate, sodium 5-sulfoisophthalate and 1,4-butanediol is 100:100:0.4:240; Dissolve the sulfonated polyester and sodium dodecylbenzenesulfonate in dichloromethane and stir until completely transparent to prepare oil phase A; the mass ratio of the sulfonated polyester, dichloromethane and sodium dodecylbenzenesulfonate is 1:12:0.03; Step S2, adding ethylene-vinyl acetate copolymer: dissolving ethylene-vinyl acetate copolymer in oil phase A to prepare oil phase B; the mass ratio of the ethylene-vinyl acetate copolymer to the oil phase A is 1:10; the mass fraction of vinyl acetate homopolymer in the ethylene-vinyl acetate copolymer is 25%; the dissolution temperature is 70° C., and the dissolution time is 1 hour; Step S3, active ingredient loading: dispersing the active ingredient in oil phase B to prepare oil phase C; the mass ratio of the active ingredient to oil phase B is 1:30; the dispersion method is ultrasonic dispersion, the ultrasonic dispersion frequency is 20 kHz, and the time is 30 minutes; the particle size D50 of the particles in the oil phase C is 1 μm; the active ingredient is diprofenocet; Step S4, adding diphenylmethane diisocyanate: dissolving diphenylmethane diisocyanate in oil phase C to prepare oil phase D; the mass ratio of diphenylmethane diisocyanate to oil phase C is 1:20; Step S5, preparing a ternary acrylic acid copolymer solution: dissolving the ternary acrylic acid copolymer and sodium dodecylbenzenesulfonate in ethyl acetate to prepare a ternary acrylic acid copolymer solution E; the particle size D50 of the ternary acrylic acid copolymer solution is 200 nm; the finger-gallery ratio of the ternary acrylic acid copolymer, sodium dodecylbenzenesulfonate, and ethyl acetate is 1:0.4:88; the mass ratio of methyl methacrylate, 2-butyl acrylate, and acrylic acid in the ternary acrylic acid copolymer is 1:1:0.1; and the dissolution temperature is 50° C.; Step S6, partially hydrolyzing polyvinyl acetate: dissolving polyvinyl acetate in methanol to prepare solution F; the mass ratio of polyvinyl acetate to methanol is 1:5; the dissolution temperature is 50°C, and the dissolution time is 2 hours; adding sodium hydroxide to solution F to carry out a hydrolysis reaction; the molar ratio of sodium hydroxide to vinyl acetate units is 0.5:1, the hydrolysis reaction temperature is 60°C, and the reaction time is 3 hours; adjusting the pH to 7 with acetic acid to terminate the reaction; adding excess acetone to collect the precipitate; filtering the precipitate, washing with deionized water, and vacuum drying to prepare partially hydrolyzed polyvinyl acetate; the vacuum drying temperature is 60°C; the degree of hydrolysis of the partially hydrolyzed polyvinyl acetate is 50% to 80%; the 50% means that 50% of the acetate groups are hydrolyzed; dispersing the partially hydrolyzed polyvinyl acetate in ternary acrylic acid copolymer solution E to prepare solution G; the mass ratio of the partially hydrolyzed polyvinyl acetate to the ternary acrylic acid copolymer solution E is 1:15; Step S7, aqueous phase preparation: dissolving sucrose ester and sodium dioctyl sulfosuccinate in deionized water, and adjusting the pH to 6.8-7.2 with sodium hydroxide to prepare aqueous phase H; the mass ratio of the sucrose ester, sodium dioctyl sulfosuccinate, and deionized water is 1:0.1:120; Step S8, chelating copper ions with zeolite: dispersing zeolite and copper hydroxide in aqueous phase H to form aqueous phase I; the mass ratio of the zeolite, copper hydroxide, and aqueous phase H is 1:0.8:8; the zeolite particle size D50 is 5 μm; and the dispersion time is 3 hours; Step S9, adding humic acid: dispersing humic acid in aqueous phase I to form aqueous phase J; the mass ratio of humic acid to aqueous phase I is 1:19; the dispersion time is 3 hours; the humic acid is derived from natural organic matter peat or lignite, and the humic acid meets organic certification standards; Step S10, adding ethylenediamine: dispersing ethylenediamine in aqueous phase J to prepare aqueous phase K; the mass ratio of ethylenediamine to aqueous phase J is 1:100; Step S11, gradient emulsification-interfacial polymerization reaction: adding oil phase D and solution G to aqueous phase K, homogenizing, and performing emulsification-interfacial polymerization reaction to prepare a crude emulsion L; the emulsification-interfacial polymerization reaction includes a first-stage emulsification-interfacial polymerization reaction, a second-stage emulsification-interfacial polymerization reaction, and a third-stage emulsification-interfacial polymerization reaction; during the first-stage emulsification-interfacial polymerization reaction, the mass ratio of oil phase D, solution G, and aqueous phase K is 1:0.3:10; continuing to add oil phase D to make the mass ratio of oil phase D to aqueous phase K 1:5, homogenizing, and performing the second-stage emulsification-interfacial polymerization reaction; continuing to add oil phase D to make the mass ratio of oil phase D to aqueous phase K 1:3.5, homogenizing, and performing the third-stage emulsification-interfacial polymerization reaction; the homogenizing speed is 18000 rpm; the emulsification-interfacial polymerization reaction time is 2 hours; the emulsification-interfacial polymerization reaction temperature is 50°C; the emulsification-interfacial polymerization reaction pH is 8.5; Step S12, high-pressure fine homogenization: sodium chloride is added to the crude emulsion L, and high-pressure homogenization is performed to prepare an emulsion M; the sodium chloride concentration in the crude emulsion L is 5 mmol / L; the high-pressure homogenization pressure is 700 bar; Step S13, freeze drying: the emulsion M is freeze-dried to prepare a seed dressing; the pre-freezing temperature of the freeze drying is -30°C, and the pre-freezing time is 4 hours; the sublimation drying temperature of the freeze drying is -10°C, and the sublimation drying time is 24 hours; the sublimation drying vacuum degree is 1 mbar; the desorption drying temperature of the freeze drying is 25°C, and the desorption drying time is 6 hours; the desorption drying vacuum degree is 0.5 mbar.

[0036] Example 2

[0037] Step S1, preparing sulfonated polyester: adding adipic acid, dimethyl terephthalate and sodium 5-sulfoisophthalate into a reactor, and carrying out an ester exchange reaction with excess 1,4-butanediol under nitrogen protection; then carrying out a polycondensation reaction to obtain sulfonated polyester; the ester exchange reaction temperature is 160° C., and the reaction time is 2.5 hours; the polycondensation reaction temperature is 210° C., and the reaction time is 5 hours; the vacuum degree of the polycondensation reaction is 8 mbar; the viscosity of the sulfonated polyester is 0.8 dL / g; the molar ratio of adipic acid, dimethyl terephthalate, sodium 5-sulfoisophthalate and 1,4-butanediol is 100:100:0.7:250; Dissolve the sulfonated polyester and sodium dodecylbenzenesulfonate in dichloromethane and stir until completely transparent to prepare oil phase A; the mass ratio of the sulfonated polyester, dichloromethane and sodium dodecylbenzenesulfonate is 1:14:0.04; Step S2, adding ethylene-vinyl acetate copolymer: dissolving ethylene-vinyl acetate copolymer in oil phase A to prepare oil phase B; the mass ratio of the ethylene-vinyl acetate copolymer to the oil phase A is 1:12; the mass fraction of vinyl acetate homopolymer in the ethylene-vinyl acetate copolymer is 28%; the dissolution temperature is 75° C., and the dissolution time is 1.5 hours; Step S3, active ingredient loading: dispersing the active ingredient in oil phase B to prepare oil phase C; the mass ratio of the active ingredient to oil phase B is 1:35; the dispersion method is ultrasonic dispersion, the ultrasonic dispersion frequency is 20 kHz, and the time is 30 minutes; the particle size D50 of the particles in the oil phase C is 1.5 μm; the active ingredient is diprofenocet; Step S4, adding diphenylmethane diisocyanate: dissolving diphenylmethane diisocyanate in oil phase C to prepare oil phase D; the mass ratio of diphenylmethane diisocyanate to oil phase C is 1:22; Step S5, preparing a ternary acrylic acid copolymer solution: dissolving the ternary acrylic acid copolymer and sodium dodecylbenzenesulfonate in ethyl acetate to prepare a ternary acrylic acid copolymer solution E; the particle size D50 of the ternary acrylic acid copolymer solution is 300 nm; the finger-gallery ratio of the ternary acrylic acid copolymer, sodium dodecylbenzenesulfonate, and ethyl acetate is 1:0.5:90; the mass ratio of methyl methacrylate, 2-butyl acrylate, and acrylic acid in the ternary acrylic acid copolymer is 1:1.1:0.11; and the dissolution temperature is 55° C.; Step S6, partially hydrolyzing polyvinyl acetate: dissolving polyvinyl acetate in methanol to prepare solution F; the mass ratio of polyvinyl acetate to methanol is 1:7; the dissolution temperature is 52°C, and the dissolution time is 2.5 hours; adding sodium hydroxide to solution F to carry out a hydrolysis reaction; the molar ratio of sodium hydroxide to vinyl acetate units is 0.7:1, the hydrolysis reaction temperature is 65°C, and the reaction time is 4 hours; adjusting the pH to 7 with acetic acid to terminate the reaction; adding excess acetone to collect the precipitate; filtering the precipitate, washing with deionized water, and vacuum drying to prepare partially hydrolyzed polyvinyl acetate; the vacuum drying temperature is 65°C; the degree of hydrolysis of the partially hydrolyzed polyvinyl acetate is 70%; the 70% means that 70% of the acetate groups are hydrolyzed; dispersing the partially hydrolyzed polyvinyl acetate in ternary acrylic acid copolymer solution E to prepare solution G; the mass ratio of the partially hydrolyzed polyvinyl acetate to the ternary acrylic acid copolymer solution E is 1:18; Step S7, aqueous phase preparation: dissolving sucrose ester and sodium dioctyl sulfosuccinate in deionized water, adjusting the pH to 6.8-7.2 with sodium hydroxide to prepare aqueous phase H; the mass ratio of the sucrose ester, sodium dioctyl sulfosuccinate, and deionized water is 1:0.15:130; Step S8, chelating copper ions with zeolite: dispersing zeolite and copper hydroxide in aqueous phase H to form aqueous phase I; the mass ratio of the zeolite, copper hydroxide, and aqueous phase H is 1:0.9:9; the zeolite particle size D50 is 8 μm; and the dispersion time is 4 hours; Step S9, adding humic acid: dispersing humic acid in aqueous phase I to form aqueous phase J; the mass ratio of humic acid to aqueous phase I is 1:20; the dispersion time is 4 hours; the humic acid is derived from natural organic matter peat or lignite, and the humic acid meets organic certification standards; Step S10, adding ethylenediamine: dispersing ethylenediamine in aqueous phase J to prepare aqueous phase K; the mass ratio of ethylenediamine to aqueous phase J is 1:110; Step S11, gradient emulsification-interfacial polymerization reaction: adding oil phase D and solution G to aqueous phase K, homogenizing, and conducting emulsification-interfacial polymerization reaction to prepare a crude emulsion L; the emulsification-interfacial polymerization reaction includes a first-stage emulsification-interfacial polymerization reaction, a second-stage emulsification-interfacial polymerization reaction, and a third-stage emulsification-interfacial polymerization reaction; during the first-stage emulsification-interfacial polymerization reaction, the mass ratio of oil phase D, solution G, and aqueous phase K is 1:0.3:10; continuing to add oil phase D to make the mass ratio of oil phase D to aqueous phase K 1:5, homogenizing, and conducting the second-stage emulsification-interfacial polymerization reaction; continuing to add oil phase D to make the mass ratio of oil phase D to aqueous phase K 1:3.5, homogenizing, and conducting the third-stage emulsification-interfacial polymerization reaction; the homogenizing speed is 18000 rpm; the emulsification-interfacial polymerization reaction time is 3 hours; the emulsification-interfacial polymerization reaction temperature is 55°C; the emulsification-interfacial polymerization reaction pH is 8.7; Step S12, high-pressure fine homogenization: sodium chloride is added to the crude emulsion L, and high-pressure homogenization is performed to prepare an emulsion M; the sodium chloride concentration in the crude emulsion L is 5 mmol / L; the high-pressure homogenization pressure is 700 bar; Step S13, freeze drying: the emulsion M is freeze-dried to prepare a seed dressing; the pre-freezing temperature of the freeze drying is -30°C, and the pre-freezing time is 4 hours; the sublimation drying temperature of the freeze drying is -10°C, and the sublimation drying time is 24 hours; the sublimation drying vacuum degree is 1 mbar; the desorption drying temperature of the freeze drying is 25°C, and the desorption drying time is 6 hours; the desorption drying vacuum degree is 0.5 mbar.

[0038] Example 3

[0039] Step S1, preparing sulfonated polyester: adding adipic acid, dimethyl terephthalate and sodium 5-sulfoisophthalate into a reactor, and carrying out an ester exchange reaction with excess 1,4-butanediol under nitrogen protection; then carrying out a polycondensation reaction to obtain sulfonated polyester; the ester exchange reaction temperature is 180° C., and the reaction time is 3 hours; the polycondensation reaction temperature is 220° C., and the reaction time is 6 hours; the vacuum degree of the polycondensation reaction is 9 mbar; the viscosity of the sulfonated polyester is 0.9 dL / g; the molar ratio of adipic acid, dimethyl terephthalate, sodium 5-sulfoisophthalate and 1,4-butanediol is 100:100:1:260; Dissolve the sulfonated polyester and sodium dodecylbenzenesulfonate in dichloromethane and stir until completely transparent to prepare oil phase A; the mass ratio of the sulfonated polyester, dichloromethane and sodium dodecylbenzenesulfonate is 1:15:0.05; Step S2, adding ethylene-vinyl acetate copolymer: dissolving ethylene-vinyl acetate copolymer in oil phase A to prepare oil phase B; the mass ratio of the ethylene-vinyl acetate copolymer to the oil phase A is 1:15; the mass fraction of vinyl acetate homopolymer in the ethylene-vinyl acetate copolymer is 30%; the dissolution temperature is 80° C., and the dissolution time is 2 hours; Step S3, active ingredient loading: dispersing the active ingredient in oil phase B to prepare oil phase C; the mass ratio of the active ingredient to oil phase B is 1:40; the dispersion method is ultrasonic dispersion, the ultrasonic dispersion frequency is 20 kHz, and the time is 30 minutes; the particle size D50 of the particles in the oil phase C is 1.9 μm; the active ingredient is diprofenocet; Step S4, adding diphenylmethane diisocyanate: dissolving diphenylmethane diisocyanate in oil phase C to prepare oil phase D; the mass ratio of diphenylmethane diisocyanate to oil phase C is 1:25; Step S5, preparing a ternary acrylic acid copolymer solution: dissolving the ternary acrylic acid copolymer and sodium dodecylbenzenesulfonate in ethyl acetate to prepare a ternary acrylic acid copolymer solution E; the particle size D50 of the ternary acrylic acid copolymer solution is 450 nm; the finger-gallery ratio of the ternary acrylic acid copolymer, sodium dodecylbenzenesulfonate, and ethyl acetate is 1:0.6:92; the mass ratio of methyl methacrylate, 2-butyl acrylate, and acrylic acid in the ternary acrylic acid copolymer is 1:1.2:0.12; and the dissolution temperature is 60°C; Step S6, partially hydrolyzing polyvinyl acetate: dissolving polyvinyl acetate in methanol to prepare solution F; the mass ratio of polyvinyl acetate to methanol is 1:10; the dissolution temperature is 55°C, and the dissolution time is 3 hours; adding sodium hydroxide to solution F to carry out a hydrolysis reaction; the molar ratio of sodium hydroxide to vinyl acetate units is 0.8:1, the hydrolysis reaction temperature is 70°C, and the reaction time is 5 hours; adjusting the pH to 7 with acetic acid to terminate the reaction; adding excess acetone to collect the precipitate; filtering the precipitate, washing with deionized water, and vacuum drying to prepare partially hydrolyzed polyvinyl acetate; the vacuum drying temperature is 70°C; the degree of hydrolysis of the partially hydrolyzed polyvinyl acetate is 80%; the 580% means that 80% of the acetate groups are hydrolyzed; dispersing the partially hydrolyzed polyvinyl acetate in ternary acrylic acid copolymer solution E to prepare solution G; the mass ratio of the partially hydrolyzed polyvinyl acetate to the ternary acrylic acid copolymer solution E is 1:20; Step S7, aqueous phase preparation: dissolving sucrose ester and sodium dioctyl sulfosuccinate in deionized water, adjusting the pH to 6.8-7.2 with sodium hydroxide to prepare aqueous phase H; the mass ratio of the sucrose ester, sodium dioctyl sulfosuccinate, and deionized water is 1:0.2:140; Step S8, chelating copper ions with zeolite: dispersing zeolite and copper hydroxide in aqueous phase H to form aqueous phase I; the mass ratio of the zeolite, copper hydroxide, and aqueous phase H is 1:1:10; the zeolite particle size D50 is 9 μm; and the dispersion time is 5 hours; Step S9, adding humic acid: dispersing humic acid in aqueous phase I to form aqueous phase J; the mass ratio of humic acid to aqueous phase I is 1:21; the dispersion time is 5 hours; the humic acid is derived from natural organic matter peat or lignite, and the humic acid meets organic certification standards; Step S10, adding ethylenediamine: dispersing ethylenediamine in aqueous phase J to prepare aqueous phase K; the mass ratio of ethylenediamine to aqueous phase J is 1:120; Step S11, gradient emulsification-interfacial polymerization reaction: adding oil phase D and solution G to aqueous phase K, homogenizing, and performing emulsification-interfacial polymerization reaction to prepare a crude emulsion L; the emulsification-interfacial polymerization reaction includes a first-stage emulsification-interfacial polymerization reaction, a second-stage emulsification-interfacial polymerization reaction, and a third-stage emulsification-interfacial polymerization reaction; during the first-stage emulsification-interfacial polymerization reaction, the mass ratio of oil phase D, solution G, and aqueous phase K is 1:0.3:10; continuing to add oil phase D to make the mass ratio of oil phase D to aqueous phase K 1:5, homogenizing, and performing the second-stage emulsification-interfacial polymerization reaction; continuing to add oil phase D to make the mass ratio of oil phase D to aqueous phase K 1:3.5, homogenizing, and performing the third-stage emulsification-interfacial polymerization reaction; the homogenizing speed is 18000 rpm; the emulsification-interfacial polymerization reaction time is 4 hours; the emulsification-interfacial polymerization reaction temperature is 60°C; the emulsification-interfacial polymerization reaction pH is 9.0; Step S12, high-pressure fine homogenization: sodium chloride is added to the crude emulsion L, and high-pressure homogenization is performed to prepare an emulsion M; the sodium chloride concentration in the crude emulsion L is 5 mmol / L; the high-pressure homogenization pressure is 700 bar; Step S13, freeze drying: the emulsion M is freeze-dried to prepare a seed dressing; the pre-freezing temperature of the freeze drying is -30°C, and the pre-freezing time is 4 hours; the sublimation drying temperature of the freeze drying is -10°C, and the sublimation drying time is 24 hours; the sublimation drying vacuum degree is 1 mbar; the desorption drying temperature of the freeze drying is 25°C, and the desorption drying time is 6 hours; the desorption drying vacuum degree is 0.5 mbar.

[0040] Comparative Example 1

[0041] In step S1, no sodium 5-sulfoisophthalate was added, and other steps and parameters were the same as those in Example 1.

[0042] The seed dressing agent was reconstituted with sterile water at a mass ratio of 1:5. Dynamic light scattering (DLS) was used to determine the particle size distribution.

[0043] Storage stability test: Use sterile water to reconstitute the seed dressing agent, with the mass ratio of seed dressing agent to sterile water being 1:5; let it stand at 25°C for 7 days and observe whether there is stratification or precipitation.

[0044] The test results are shown in the table below. Sulfonated polyester can improve the emulsification and dispersibility of seed dressings. Ionization of the sulfonic acid groups increases hydrophilicity, promoting stable dispersion of the polyester in the aqueous phase and improving the emulsification and dispersibility of the seed dressing.

[0045] Table 1: Effect of sulfonated polyester on the emulsification and dispersibility of seed dressing

[0046] Comparative Example 2

[0047] In step S2, vinyl acetate copolymer is used instead of ethylene-vinyl acetate copolymer; other steps and parameters are consistent with those in Example 1.

[0048] Comparative Example 3

[0049] In step S4, diphenylmethane diisocyanate was not added to the oil phase; in step S10, ethylenediamine was not added to the aqueous phase; and no interfacial polymerization reaction was performed; other steps and parameters were consistent with those in Example 1.

[0050] Method for determining sustained-release capacity: (1) In order to explore the slow-release ability of the seed dressing agent, this study used soil extract as the release medium to simulate actual sowing conditions. 0.5 kg of unfertilized soil was placed in a 3000 mL triangular flask, 1000 mL of distilled water was added, and the mixture was stirred thoroughly. The bottle mouth was then sealed with a breathable sealing film and the bottle was placed in a high-pressure steam sterilizer for heating at 121°C for 2 h. After cooling, the mixture was sterile filtered. The supernatant was poured into a 1000 mL constant volume flask, and then sterile distilled water was added to make the volume 1000 mL. The soil extract was stored at 4°C for later use.

[0051] (2) Use sterile water to reconstitute the seed dressing agent, and the mass ratio of the seed dressing agent to sterile water is 1:5; use the shaking plate method to coat the surface sterilized rice seeds (Nanjing 5055) (the mass ratio of rice seeds to the reconstituted seed dressing is 1:20), dry them, and set aside.

[0052] (3) Place 100 seeds treated with the seed dressing agent in 100 mL of soil extract. Take 0.5 mL of the extract on days 1, 7, 14, and 21, and measure the concentration of abifenprofen in the extract, represented by A. At the same time, add 0.5 mL of soil extract to the centrifuge tube. Place 100 seeds treated with the seed dressing agent in 100 mL of soil extract, grind and thoroughly treat with ultrasound to completely release abifenprofen. Measure the concentration of abifenprofen in the suspension, represented by B. The release rate is expressed as A / B × 100%.

[0053] The test results are shown in the table below. Sulfonated polyesters can significantly improve the sustained-release capability of seed dressings. This is likely due to the sulfonic acid groups regulating the polyester's swelling properties, slowing the release rate of pesticides (such as diprofenoprene). This allows for a slow release of the drug, avoiding initial drug waste while ensuring sustained release of the effective drug after sowing.

[0054] Compared to vinyl acetate copolymers, ethylene-vinyl acetate copolymers can further improve the sustained-release properties of drugs in seed dressings. This may be due to the following: the ethylene segments (hydrophobic regions) in ethylene-vinyl acetate copolymers form a physical cross-linked network that restricts pesticide diffusion, while the vinyl acetate segments (amorphous regions) stabilize the pesticide molecules through polar interactions (such as hydrogen bonding). This dynamic balance enables ethylene-vinyl acetate copolymers to achieve a low burst release rate. However, the homogeneous structure of vinyl acetate copolymers lacks a hydrophobic barrier, resulting in excessively rapid migration of pesticide molecules.

[0055] Interfacial polymerization can improve the sustained-release properties of drug-dressing agents. Interfacial polymerization is a condensation reaction that occurs at the oil-water interface. Its core process involves dissolving the oil-soluble monomer diphenylmethane diisocyanate in the organic phase (e.g., oil droplets containing the active ingredient) and the water-soluble monomer ethylenediamine in the aqueous phase. Upon surface contact, a nucleophilic addition reaction (-NCO + -NH2 → -NH-CO-NH-) forms the high-molecular-weight polymer polyurea, forming a dense microcapsule wall that encapsulates the active ingredient and maintains its release pathway. The hydrophobic cross-linked network of polyurea slows water penetration, controlling the rate of drug exchange. Polyurea also achieves sustained-release properties through slow hydrolysis (-NH-CO- + H2O → -NH2 + CO2) in the slightly acidic soil environment (pH 6.5).

[0056] Table 2: Effects of main steps on sustained release of seed dressing agents

[0057] Comparative Example 4

[0058] In step S6, completely hydrolyzed polyvinyl acetate is used instead of partially hydrolyzed polyvinyl acetate, and other steps and parameters are consistent with those in Example 1.

[0059] Comparative Example 5

[0060] In step S6, unhydrolyzed polyvinyl acetate is used instead of partially hydrolyzed polyvinyl acetate, and other steps and parameters are consistent with those in Example 1.

[0061] Comparative Example 6

[0062] In step S5, a dibasic acrylic acid copolymer is used instead of a ternary acrylic acid copolymer, and other steps and parameters are consistent with those in Example 1; the mass ratio of methyl methacrylate to acrylic acid in the dibasic acrylic acid copolymer is 1:(0.1-0.12).

[0063] Method for determining the shedding rate of seed dressing: weigh the initial mass of rice seeds before coating (W0); reconstitute the seed dressing with sterile water at a ratio of 1:5; coat surface-sterilized rice seeds (Nanjing 5055) using the shaking plate method (mass ratio of rice seeds to reconstituted seed dressing is 1:20), dry, and weigh the initial mass of the coated seeds (W1); simulate mechanical friction during transportation / sowing by rotating the drum (rotating drum speed is 35 rpm, simulation time is 2 hours), collect and weigh the shedding material (W2), and calculate the shedding rate: shedding rate = W2 / (W1- W0) × 100%.

[0064] The test results are shown in the table below. Adding partially hydrolyzed polyvinyl acetate can reduce the shedding rate of seed dressings. This may be due to the following: hydroxyl groups (-OH) provide strong hydrogen bonding, enhancing adhesion to the seed surface, while residual acetate groups (-OCOCH3) inhibit excessive membrane swelling through hydrophobic interactions, maintaining mechanical strength. In contrast, unhydrolyzed polyvinyl acetate, due to its complete hydrophobicity (relying solely on physical adsorption), results in a high shedding rate. However, fully hydrolyzed polyvinyl acetate (>99% hydroxyl groups) is overly hydrophilic, causing the membrane to soften and swell, resulting in a higher shedding rate.

[0065] Ternary acrylic acid copolymers can reduce the shedding rate of seed dressing agents. This may be because the butyl chain (C4H9) of butyl acrylate in the ternary acrylic acid copolymer couples with the waxy layer on the seed surface through van der Waals forces, increasing the binding force between the seed dressing agent and the seed surface and reducing the shedding rate.

[0066] Table 3: Effect of partially hydrolyzed polyvinyl acetate on the shedding rate of seed dressing

[0067] Comparative Example 7

[0068] In step S8, no zeolite was added, and other steps and parameters were the same as those in Example 1.

[0069] Comparative Example 8

[0070] In step S9, humic acid was not added, and other steps and parameters were the same as those in Example 1.

[0071] Comparative Example 9

[0072] In step S8, copper sulfate is used instead of copper hydroxide, and other steps and parameters are consistent with those in Example 1.

[0073] Comparative Example 10

[0074] In step S8, copper chloride is used instead of copper hydroxide, and other steps and parameters are consistent with those in Example 1.

[0075] Method for determining the sustained-release ability: In order to explore the sustained-release ability of the seed dressing agent, this study used soil extract as the release medium to simulate actual sowing conditions. Place 0.5 kg of unfertilized soil in a 3000 mL triangular flask, add 1000 mL of distilled water, and stir thoroughly. Then seal the bottle mouth with a breathable sealing film, and place the bottle in a high-pressure steam sterilizer for heating at 121°C for 2 hours. After taking it out and cooling, sterile filter it. Pour the supernatant into a 1000 mL constant-volume flask, then add sterile distilled water to make the volume 1000 mL, and store the soil extract at 4°C for later use.

[0076] The seed dressing agent was reconstituted with sterile water at a ratio of 1:5. Surface-sterilized rice seeds (Nanjing 5055) were coated using the shaking plate method (the mass ratio of rice seeds to the reconstituted seed dressing agent was 1:20), dried, and set aside.

[0077] Place 100 seeds treated with seed dressing in 100 mL of soil extract. Remove 0.5 mL of the extract on days 1, 7, 14, and 21, and measure the copper ion concentration. Simultaneously, add 0.5 mL of soil extract to a centrifuge tube. Place 100 seeds treated with seed dressing in 100 mL of soil extract. Grind and ultrasonicate thoroughly to completely release the copper ions. Measure the copper ion concentration in the suspension, expressed as B. The release rate is expressed as A / B × 100%.

[0078] The test results are shown in the table below. Zeolite can significantly improve the slow-release capacity of copper ions in seed dressings. The possible reason is that zeolite is a porous aluminosilicate mineral with regular cavities and channels in its three-dimensional skeleton structure, and its surface has a permanent negative charge. The exchangeable cations in zeolite (such as N 、 ) and Cu in solution A replacement reaction occurs, Cu Fixed on the framework. The nanoscale pores (0.3-1 nm) of zeolite can also limit the Diffusion rate to avoid explosive release.

[0079] Humic acid can further improve the slow-release capacity of copper ions in seed dressing. The possible reason is that humic acid is a natural organic polymer containing active functional groups such as carboxyl (-COOH) and phenolic hydroxyl (-OH). Form a stable chelate (Cu-OC=O), reducing Cu Free concentration, to achieve slow release of Cu effect.

[0080] The slow-release performance of copper hydroxide is better than that of copper chloride and copper sulfate. The possible reason is that Cu(OH)2 particles can be fixed by zeolite / humic acid, and the solubility product of Cu(OH)2 is much lower than that of CuCl2 and CuSO4, so that it can only dissociate in trace amounts in the soil solution, achieving continuous low-concentration Cu Supply. In the slightly acidic environment of the rhizosphere (pH 6-7), O quilt Neutralizes, pushing the equilibrium to the right, slowly releasing Cu .

[0081] Table 4: Effects of main treatments on the slow-release capacity of copper ions in seed dressing

Claims

1. A method for preparing a rice seed dressing agent, characterized in that: The following steps are involved: Step S1, preparing sulfonated polyester: adding adipic acid, dimethyl terephthalate and sodium 5-sulfoisophthalate to a reactor, and carrying out an ester exchange reaction with excess 1,4-butanediol under nitrogen protection; then carrying out a polycondensation reaction to obtain sulfonated polyester; dissolving the sulfonated polyester and sodium dodecylbenzenesulfonate in dichloromethane to prepare oil phase A; Step S2, adding ethylene-vinyl acetate copolymer: dissolving ethylene-vinyl acetate copolymer in oil phase A to prepare oil phase B; Step S3, active ingredient loading: dispersing the active ingredient in oil phase B to prepare oil phase C; Step S4, adding diphenylmethane diisocyanate: dissolving diphenylmethane diisocyanate in the oil phase C to prepare the oil phase D; Step S5, preparing a ternary acrylic acid copolymer solution: dissolving the ternary acrylic acid copolymer and sodium dodecylbenzenesulfonate in ethyl acetate to prepare a ternary acrylic acid copolymer solution E; Step S6, partially hydrolyzing polyvinyl acetate: dissolving polyvinyl acetate in methanol to prepare solution F; adding sodium hydroxide to solution F to carry out a hydrolysis reaction; adjusting the pH with acetic acid to terminate the reaction; adding excess acetone to collect the precipitate; filtering the precipitate, washing with deionized water, and vacuum drying to prepare partially hydrolyzed polyvinyl acetate; dispersing the partially hydrolyzed polyvinyl acetate in ternary acrylic acid copolymer solution E to prepare solution G; Step S7, aqueous phase preparation: dissolving sucrose ester and sodium dioctyl sulfosuccinate in deionized water, and adjusting the pH to 6.8-7.2 with sodium hydroxide to prepare aqueous phase H; Step S8, chelating copper ions with zeolite: dispersing zeolite and copper hydroxide in aqueous phase H to form aqueous phase I; Step S9, adding humic acid: dispersing humic acid in aqueous phase I to form aqueous phase J; Step S10, adding ethylenediamine: dispersing ethylenediamine in aqueous phase J to form aqueous phase K; Step S11, gradient emulsification-interfacial polymerization reaction: adding the oil phase D and solution G to the aqueous phase K, homogenizing, and performing emulsification-interfacial polymerization reaction to prepare a crude emulsion L; Step S12, high-pressure homogenization: adding sodium chloride to the crude emulsion L and homogenizing under high pressure to prepare emulsion M; Step S13, drying: the emulsion M is dried to prepare a seed dressing agent.

2. The preparation method according to claim 1, characterized in that The active ingredient in step S3 is acyclovir.

3. The preparation method according to claim 2, characterized in that In the step S4, the mass ratio of diphenylmethane diisocyanate to the oil phase C is 1:(20-25).

4. The preparation method according to claim 3, characterized in that In step S8, the mass ratio of zeolite, copper hydroxide, and aqueous phase H is 1: (0.8-1): (8-10); the zeolite particle size D50 is ≤ 10 μm; and the dispersion time is 3 hours to 5 hours.

5. A rice seed dressing agent, characterized in that The seed dressing agent is prepared by the preparation method according to claim 1.

6. A method for improving the emulsification and dispersibility of a seed dressing agent, characterized in that: The method adopts the preparation method as claimed in claim 1.

7. A method for improving the sustained-release performance of active ingredients in seed dressings, characterized in that: The method adopts the preparation method as claimed in claim 1.

8. A method for improving the slow-release performance of copper ions in a seed dressing, characterized in that: The method adopts the preparation method as claimed in claim 1.

9. A method for reducing the shedding rate of a seed dressing agent, characterized in that: The method adopts the preparation method as claimed in claim 1.

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