A waterborne silicon-modified acrylic resin, a preparation method and application thereof

Abstract

This invention discloses a waterborne silicone-modified acrylic resin, its preparation method, and its application, specifically relating to the field of polymer coating materials for agricultural use. This invention introduces a new composite silicone-modified system of "nano-SiO2 + hydroxyl silicone oil + silane coupling agent." Pretreatment of nano-SiO2 with a silane coupling agent solves the aggregation problem, while hydroxyl silicone oil enhances the water resistance of the film. The addition of hydroxypropyl acrylate allows for precise control of crosslinking density through hydroxyl groups. The emulsifier is replaced with a mixture of sodium dodecyl sulfate and isooctylphenol polyoxyethylene ether at a ratio of 1:1.2-1:1.5, balancing emulsion dispersibility and seed compatibility. This resin exhibits uniform film formation, strong adhesion, and no adverse effects on seed germination, making it particularly suitable for coating seeds of grain crops (wheat, corn, soybean, rice), cash crops (cotton, rapeseed), and vegetable crops. It can impart a slow-release function to the coating agent, combining environmental friendliness with practical value.

Description

Technical Field

[0001] This invention relates to the field of polymer coating materials for agricultural use, specifically to a water-based silicone-modified acrylic resin, its preparation method, and its application. Background Technology

[0002] Seed coating technology, by forming a uniform protective film on the seed surface, enables pest and disease control, nutrient supply, and enhanced stress resistance, making it one of the key technologies for modern agricultural development. The coating resin used as the film-forming substrate must meet the following core requirements: 1. Low or non-toxic, not affecting seed vigor and seedling growth; 2. Good film-forming properties, rapidly forming a continuous, crack-free film at room or low temperatures; 3. Strong adhesion to the seed surface, able to withstand mechanical abrasion during processing, transportation, and sowing.

[0003] Currently, traditional acrylic resins and polyurethane resins suffer from brittle and easily cracked film layers; while nano-SiO2 modified acrylic resins can improve hardness and water resistance, the nanoparticles are prone to agglomeration, leading to uneven film layers and potentially affecting seed viability; the epoxy groups in waterborne epoxy modified acrylic resins are prone to react with the seed surface, posing a risk of inhibiting germination.

[0004] In addition, existing silicone-modified resins are mostly designed for industrial coatings, focusing on weather resistance and mechanical properties, without fully considering the special requirements of seed coating for "film-forming slow release" synergy. For example, they need to have an appropriate crosslinking density to achieve controllable release of functional components, and the pH of the system needs to match the suitable environment for seed germination to avoid negative impacts on germination.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The technical problem to be solved by this invention is how to propose a waterborne silicone-modified acrylic resin specifically for seed coating, its preparation method and application.

[0007] The present invention solves the above-mentioned technical problems through the following technical means:

[0008] This invention proposes an aqueous silicone-modified acrylic resin, comprising the following components in parts by weight: methyl methacrylate (MMA) 35-45 parts, butyl acrylate (BA) 40-50 parts, acrylic acid (AA) 5-8 parts, hydroxypropyl acrylate (HPA) 3-5 parts, nano-SiO2 2-4 parts, hydroxyl silicone oil 3-6 parts, silane coupling agent 2-3 parts, ammonium persulfate (APS) 0.8-2.0 parts, emulsifier 3-5 parts, neutralizer 3-5 parts, low-temperature crosslinking agent 1.5-3 parts, and deionized water 160-200 parts.

[0009] This invention introduces a new composite silicon-modified system consisting of "nano-SiO2 + hydroxyl silicone oil + silane coupling agent". The nano-SiO2 is pretreated with a silane coupling agent to solve the aggregation problem, while the hydroxyl silicone oil improves the water resistance and flexibility of the film layer, adapting to the dynamic process of seed water absorption and swelling. Hydroxypropyl acrylate (HPA) is also added. The HPA regulates the crosslinking density through hydroxyl groups and, together with acrylic acid (AA), enhances the adhesion to the seed surface, enabling the controlled release of functional components over 1-3 months, thus meeting the synergistic requirements of "film formation-slow release" in seed coating.

[0010] Preferably, the silane coupling agent includes, but is not limited to, at least one of KH-550 (γ-aminopropyltriethoxysilane), KH-570 (γ-methacryloyloxypropyltrimethoxysilane), KH-561 (γ-glycidyl etheroxypropylmethyldimethoxysilane), KH-792 (N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane), KH-560 (γ-glycidyl etheroxypropyltrimethoxysilane), A-151 (vinyltriethoxysilane), and A-171 (vinyltrimethoxysilane).

[0011] More preferably, the silane coupling agent is KH-560, with CAS number 2530-83-8.

[0012] Preferably, the emulsifier is a compound of anionic emulsifier and nonionic emulsifier, with a compounding mass ratio of 1:(1.2-1.5).

[0013] Preferably, the anionic emulsifier includes, but is not limited to, at least one of sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), and sodium fatty alcohol polyoxyethylene ether sulfate (AES); Preferably, the nonionic emulsifier includes, but is not limited to, at least one of octylphenol polyoxyethylene ether (OP-10), nonylphenol polyoxyethylene ether (NP-10, with an ethylene oxide addition number of 10), fatty alcohol polyoxyethylene ether (AEO-9), and Tween-80 (CAS No. 9005-65-6). More preferably, the emulsifier is a mixture of sodium dodecyl sulfate (SDS) and isooctylphenol polyoxyethylene ether (OP10) in a mass ratio of 1:(1.2-1.5).

[0014] To ensure stable emulsion polymerization and no residual toxicity after film formation.

[0015] Preferably, the neutralizing agent includes, but is not limited to, at least one of the following: ammonia solution with a mass fraction of 20%, triethylamine, diethanolamine, dilute sodium bicarbonate solution, and dilute sodium carbonate solution.

[0016] More preferably, the neutralizing agent is a 20% (w / w) ammonia solution.

[0017] The pH of the emulsion can be adjusted to 7-8. It is non-toxic to plants and does not affect the resin performance. Strong alkaline neutralizing agents (such as sodium hydroxide and potassium hydroxide) are explicitly excluded to avoid damaging seeds and compromising the stability of the emulsion.

[0018] Preferably, the low-temperature crosslinking agent includes, but is not limited to, a combination of multiple of diacetone acrylamide (DAAM), adipic acid dihydrazide (ADH), and malonyl hydrazide.

[0019] More preferably, the low-temperature crosslinking agent is a combination of 1-2 parts of diacetone acrylamide and 0.5-1.0 parts of adipic acid dihydrazide.

[0020] The core requirements for crosslinking agents are: crosslinking at room temperature, improving the wear resistance and water resistance of the film, and having no plant toxicity.

[0021] This invention also proposes a method for preparing the above-mentioned waterborne silicone-modified acrylic resin, comprising the following steps: (1) Pretreatment of silicon modifier: Nano-SiO2 and silane coupling agent are added to deionized water, ultrasonically dispersed, and hydroxyl silicone oil is added to obtain composite silicon modifier dispersion; (2) Seed emulsion polymerization: a. Pre-emulsification: Add the emulsifier to deionized water; then add methyl methacrylate, butyl acrylate, acrylic acid, hydroxypropyl acrylate and diacetone acrylamide to obtain a pre-emulsified monomer solution; b. Preparation of seed emulsion: Add pre-emulsified monomer solution and ammonium persulfate aqueous solution under an inert atmosphere, keep warm, and obtain seed emulsion; c. Adding copolymerization: Mix the pre-emulsified monomer solution with the composite silicon modifier dispersion prepared in step (1) as a mixed adding solution; add the mixed adding solution and ammonium persulfate aqueous solution separately to the reaction flask containing the seed emulsion and heat up; (3) Post-treatment and cross-linking: Cool the reaction system of step (2), add neutralizing agent and adipic acid dihydrazide aqueous solution in sequence, and filter.

[0022] This invention employs a silicon modifier pretreatment + seed emulsion polymerization process, which can form a film quickly at room temperature without high temperature. The core performance features are biosafety (seed germination rate ≥95%), abrasion resistance (film shedding rate <5%), and slow-release function (controllable release over 1-3 months). The pH of the system is strictly controlled at 7-8 to match the suitable environment for seed germination and avoid inhibiting germination.

[0023] Preferably, in step (1), the ultrasonic dispersion conditions are 300 W power, 25 kHz, 40-60 min time, and 65-75℃ temperature.

[0024] The nanoparticles were dispersed by ultrasonication at 300W for 40-60 minutes and reacted at a low temperature of 65-75℃. Hydroxy silicone oil was then added and stirred to ensure uniform dispersion of the nanoparticles and to avoid agglomerated particles scratching the seed coat.

[0025] Preferably, in step (a), the emulsifier is a mixture of anionic and nonionic emulsifiers with a mass ratio of 1:(1.2-1.5).

[0026] Preferably, the anionic emulsifier includes, but is not limited to, at least one of sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), and sodium fatty alcohol polyoxyethylene ether sulfate (AES); Preferably, the nonionic emulsifier includes, but is not limited to, at least one of octylphenol polyoxyethylene ether (OP-10), nonylphenol polyoxyethylene ether (NP-10, with an ethylene oxide addition number of 10), fatty alcohol polyoxyethylene ether (AEO-9), and Tween-80 (CAS No. 9005-65-6). More preferably, the emulsifier is a compound of sodium dodecyl sulfate (SDS) and isooctylphenol polyoxyethylene ether (OP10) in a mass ratio of 1:1.2-1:1.5.

[0027] Preferably, in step (b), the inert atmosphere refers to purging with nitrogen for 20-30 minutes to remove oxygen.

[0028] Preferably, in step (b), the heat preservation method is to raise the temperature to 75-80℃ and keep the reaction at that temperature for 30-40 min until the system exhibits a pale blue fluorescence.

[0029] The seed emulsion prepared in step (b) serves as the "growth core" for subsequent polymerization, providing stable reaction sites and avoiding problems such as uneven particle size and flocculation during monomer polymerization, thus ensuring that the final resin emulsion particle size is controlled within 80-120 nm.

[0030] Preferably, in step (c), the volume ratio of the pre-emulsified monomer liquid to the composite silicone modifier dispersion obtained in step (1) is 2-3:1, and more preferably 3:1.

[0031] Preferably, in step (c), the dripping time is 2.5-3 h.

[0032] Preferably, in step (c), the heating method is to heat to 82-85℃ and hold for 1.5-2 hours.

[0033] In step c, the separate addition of the mixed drop solution and the ammonium persulfate aqueous solution allows for precise control of the contact rate between the initiator and the monomer. This avoids excessively high local initiator concentrations, which could lead to violent polymerization and uneven emulsion particle size. Simultaneously, it ensures uniform grafting of the silicone modifier and monomer. During the drop addition process, the seed emulsion acts as a "core template," with the monomer continuously polymerizing on its surface, achieving "seed growth" and ensuring a stable and controllable polymerization reaction. The drop addition rate is controlled so that the total drop addition time is approximately 2.5-3 hours. After the drop addition is complete, the temperature is raised to 82-85℃ and held for 1.5 hours to ensure a monomer conversion rate greater than 98%.

[0034] The conversion of acrylic monomers into polymer chains of waterborne silicone-modified acrylic resins is a process in which monomers form high molecular weight polymers through polymerization reactions, with a monomer conversion rate greater than 98%.

[0035] Preferably, in step (3), the temperature is lowered to 40-45℃.

[0036] After polymerization at 75-85℃, the temperature is lowered to 40-45℃ and DAAM / ADH is added for low-temperature crosslinking. This avoids high-temperature toxicity and improves the abrasion resistance of the film (peeling rate <5%), making it suitable for mechanical friction during seed processing and transportation.

[0037] Preferably, in step (3), the neutralizing agent includes, but is not limited to, at least one of the following: ammonia solution with a mass fraction of 20%, triethylamine, diethanolamine, dilute sodium bicarbonate solution, and dilute sodium carbonate solution.

[0038] More preferably, the neutralizing agent is a 20% (w / w) ammonia solution.

[0039] Preferably, in step (3), the filtration method is to use 150-200 mesh nylon cloth for filtration, and more preferably 200 mesh nylon cloth for filtration.

[0040] A water-based silicone-modified acrylic resin emulsion with a solid content of 30-35% and a particle size of 80-120 nm was obtained by filtration.

[0041] The present invention also proposes the application of the waterborne silicone-modified acrylic resin emulsion prepared by the above preparation method in seed coating.

[0042] The application method involves using water-based silicone-modified acrylic resin emulsion in the preparation of seed coating agents.

[0043] The present invention also proposes a seed coating agent, which, by mass percentage, comprises 20-40 wt% of the above-mentioned waterborne silicone-modified acrylic resin emulsion, 5-10 wt% of natural modified wax emulsion, 5-12 wt% of colorant, 3-8 wt% of filler, 2-5 wt% of antifreeze, 0.1-0.5 wt% of rheology modifier, 0.1-0.2 wt% of preservative, 0.3-0.8 wt% of plant-derived antibacterial adjuvant, and the remainder being deionized water.

[0044] Preferably, the natural modified wax emulsion is an emulsified aqueous system, wherein the modification is used to improve the hydrophilicity, dispersibility and compatibility of the natural wax with the system; it is prepared using conventional emulsification processes in the art, including heating the natural wax to a molten state, adding an emulsifier for mixing and emulsification, and then subjecting it to high-pressure homogenization to obtain a stable aqueous wax emulsion.

[0045] Preferably, the natural modified wax emulsion includes one or more of carnauba wax modified emulsion, rice bran wax modified emulsion, beeswax modified emulsion, and insect wax modified emulsion.

[0046] The solid content is 25-40 wt%, and the dispersed particle size is ≤1 μm.

[0047] Preferably, the colorant is selected from water-based inorganic pigment pastes; Preferably, the inorganic pigment includes, but is not limited to, at least one of iron oxide red, iron oxide yellow, iron oxide brown, titanium dioxide, ultramarine, chrome green, cobalt blue, carbon black, chrome yellow, and iron blue; the color paste is an aqueous system that has undergone dispersion treatment, with a solid content of 30-50 wt% and a dispersed particle size ≤1 μm.

[0048] Preferably, the filler includes, but is not limited to, at least two of the following: natural cellulose powder, microcrystalline cellulose powder, diatomaceous earth, vermiculite, perlite, silica, sepiolite, and talc. A further preferred formulation is a mixture of diatomaceous earth, vermiculite, and gaseous silica in a ratio of 2:1:0.5, with a particle size ≤325 mesh.

[0049] The porous nature of the material enhances the adhesion of functional ingredients and helps improve the sustained-release effect.

[0050] Preferably, the antifreeze includes, but is not limited to, at least one of propylene glycol, polypropylene glycol and its derivatives, and glycerol; A further preferred formulation is a 1:1 mixture of propylene glycol and polypropylene glycol; Preferably, the polypropylene glycol derivative includes, but is not limited to, one of propylene glycol diglycidyl ether (CAS: 26142-30-3), polypropylene glycol diacrylate (CAS: 52496-08-9), and polypropylene glycol bis(2-aminopropyl ether) (CAS: 9048-57-1); It can prevent freezing at low temperatures, ensuring stability during storage and use.

[0051] Preferably, the rheology modifier includes, but is not limited to, one of xanthan gum, guar gum, hydroxyethyl cellulose, and bentonite.

[0052] The rheological properties of the system can be adjusted to ensure uniform coating of the film during coating.

[0053] Preferably, the preservative is at least one of aqueous isothiazolinones, benzisothiazolinones, organic bromine compounds, and phenolic ethers; for example, but not limited to, Kathon, benzisothiazolinone (CAS: 2634-33-5), and bromonitrobenzene glycol (CAS: 52-51-7).

[0054] More preferably, the preservative is a Kathon-type water-based compound preservative containing 5-chloro-2-methyl-4-isothiazolin-3-one (CMI) and 2-methyl-4-isothiazolin-3-one (MI), with a mass ratio of CMI to MI of (2-4):1, preferably 3:1.

[0055] The CAS number of the 5-chloro-2-methyl-4-isothiazolin-3-one is 26172-55-4.

[0056] The CAS number of the 2-methyl-4-isothiazolin-3-one is 2682-20-4.

[0057] It can inhibit the growth of microorganisms during storage.

[0058] Preferably, the plant-derived antibacterial adjuvant is a modified eugenol derivative; The eugenol modified derivatives include, but are not limited to, one of methyl eugenol (CAS: 93-15-2), acetyl eugenol (CAS: 93-28-7), isoeugenol (CAS: 97-54-1), and epoxy eugenol (CAS: 13400-46-9).

[0059] It can help improve the effectiveness of disease prevention and control.

[0060] The present invention also proposes a method for preparing the above-mentioned seed coating agent, comprising the following steps: The aqueous silicone-modified acrylic resin emulsion, natural modified wax emulsion, colorant, antifreeze, preservative, plant-derived antibacterial agent, deionized water, and flow aid are dispersed and mixed; then filtered to obtain the final product.

[0061] Preferably, the dispersion conditions are dispersion at 800-1200 rpm for 5-20 min.

[0062] Preferably, the filtration method is to use 200-mesh nylon cloth for filtration.

[0063] The rheology modifier is completely dissolved and uniformly dispersed. The viscosity of the system is adjusted to a suitable coating range (2000-10000 mPa·s, 25℃). After dispersion, a sample is taken to test the pH value (which should be maintained at 7-8), viscosity, and dispersion uniformity of the system. If it passes the test, it is filtered through a 200-mesh nylon cloth to remove any possible impurities and agglomerated particles, thus obtaining the finished seed coating agent.

[0064] The present invention also proposes the application of the above-mentioned seed coating agent in seed coating, comprising the following steps: Mix the seeds with the seed coating agent to ensure that each seed is evenly coated with a coating film, and then dry.

[0065] Preferably, when the seeds are corn, wheat, soybean, or rice grain crop seeds, the standard dosage is 2-5 g of coating agent per kilogram of seeds.

[0066] Preferably, when the seeds are cotton, rapeseed, or other economic and vegetable crops, the standard dosage is 5-15 g of coating agent per kilogram of seeds.

[0067] The beneficial effects of this invention are as follows: 1. This invention provides an aqueous silicone-modified acrylic resin, which has the characteristics of uniform film formation, strong adhesion, and no adverse effect on seed germination. It is especially suitable for coating treatment of seeds of grain crops (wheat, corn, soybean, rice), cash crops (cotton, rapeseed) and vegetable crops. It can impart a slow-release function to the coating agent and has both environmental friendliness and practical value.

[0068] 2. Strong adhesion and good wear resistance: Through silicone modification and low-temperature cross-linking design, combined with the synergistic effect of natural modified wax emulsion and porous fillers, the resin film layer is firmly bonded to the seed surface. Tests show that after specific friction experiments, the coating layer peeling rate of coated seeds is less than 5%, which is significantly better than traditional acrylic resin coating.

[0069] 3. High biocompatibility: The resin emulsion is an aqueous system, and the pH of the finished coating agent is maintained at 7-8, which matches the suitable environment for seed germination; after coating with low-toxicity ingredients, the seed germination rate is greater than 95%, and there is no adverse effect on seedling growth.

[0070] 4. Excellent slow-release function: The resin membrane has a suitable cross-linked network structure, which, combined with the adsorption effect of porous fillers, enables the slow and continuous release of functional components in the soil through osmosis. For example, when compounded with fungicides, it can effectively control seedling diseases within 1-3 months; when compounded with nutrients, it can stably supply the needs of seedling growth.

[0071] 5. Easy to operate and widely adaptable: This seed coating agent can be directly used in existing seed coating equipment, and the production process is simple; the coating agent has good storage stability (no stratification, gelation, or precipitation after 30 days of storage at 50℃), making it easy to transport and store for a long time; it has good compatibility with different types of crop seeds and various commonly used functional ingredients, and has a wide range of applications.

[0072] Of course, implementing any product or method of the present invention does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0073] Figure 1 The results of seed abrasion experiments after applying the seed coating agents prepared in Example 1 and Comparative Example 1 of this invention to corn seeds; Figure 2 The results show the seed germination rate of corn seeds after the seed coating agents prepared in Example 1 and Comparative Example 2 of this invention were applied to corn seeds. Figure 3 The results of seed abrasion experiments after applying the seed coating agents prepared in Example 1 and Comparative Example 3 of this invention to corn seeds; Figure 4 The seed coating agents prepared in Example 1 and Comparative Example 5 of this invention were applied to lettuce seeds to determine the seed germination rate. Figure 5 The results of seed abrasion experiments after applying the seed coating agents prepared in Example 1 and Comparative Example 6 of this invention to soybean seeds; Figure 6 The effect of the sustained-release effect of the materials prepared in Example 1 and Comparative Example 6 on soybean growth is shown in Figure 1. A represents the growth status of soybean roots in Example 1, B represents the growth status of soybean roots in Comparative Example 6, C represents the growth status of soybean roots below the roots in Example 1, and D represents the growth status of soybean roots below the roots in Comparative Example 6. Figure 7 The images show the layered preparations of Example 1 and Comparative Example 4 of this invention. Detailed Implementation

[0074] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical terms used below have the same meaning as understood by those skilled in the art.

[0075] Unless otherwise specified, the test materials and reagents used in the following examples are commercially available or prepared by known methods.

[0076] Unless otherwise specified, all techniques or conditions described in the embodiments can be performed in accordance with the techniques or conditions described in the literature in this field or in the product manual. Unless otherwise specified, the quantitative experiments in the following embodiments are all repeated three times or more, and the results are averaged.

[0077] Example 1: This embodiment provides a water-based silicone-modified acrylic resin specifically for seed coating, comprising the following components by weight: 40 parts methyl methacrylate (MMA), 45 parts butyl acrylate (BA), 6 parts acrylic acid (AA), 4 parts hydroxypropyl acrylate (HPA), 3 parts nano-SiO2, 4.5 parts hydroxyl silicone oil, 2.5 parts silane coupling agent (KH560), 1.2 parts ammonium persulfate (APS), 4 parts emulsifier, 4 parts neutralizer (20% ammonia solution by mass), 2.3 parts low-temperature crosslinking agent (composed of 1.5 parts DAAM and 0.8 parts ADH), and 178 parts deionized water; the emulsifier is a compound of sodium dodecyl sulfate (SDS) and isooctylphenol polyoxyethylene ether (OP10) in a mass ratio of 1:1.4.

[0078] This embodiment provides a method for preparing the above-mentioned waterborne silicone-modified acrylic resin specifically for seed coating. The specific steps are as follows: Step 1: Silicon Modifier Pretreatment Nano-sized SiO2 (20 nm particle size) and KH560 were added to deionized water and ultrasonically dispersed (300 W, 25 kHz) for 50 min. The mixture was then heated to 70 °C and reacted at 800 rpm for 2 h. Hydroxy silicone oil was then added, and stirring continued for 30 min to obtain a composite silicone modifier dispersion, which was then cooled for later use.

[0079] Step 2: Seed emulsion polymerization 1. Pre-emulsification: Deionized water and emulsifier (sodium dodecyl sulfate (SDS) and isooctylphenol polyoxyethylene ether (OP10) in a mass ratio of 1:1.4) were added to a pre-emulsification tank and stirred at 1200 rpm for 15 min. All acrylic monomers (MMA, BA, AA, HPA) and DAAM were slowly added, and high-speed stirring was continued for 40 min to obtain a stable pre-emulsified monomer solution.

[0080] 2. Preparation of seed emulsion: In a reaction flask containing deionized water, nitrogen gas is purged for 30 min to remove oxygen, and the temperature is raised to 80°C. Approximately 15% of the pre-emulsified monomer solution and part of the APS aqueous solution (0.4 parts APS dissolved in 5 parts water) are added, and the reaction is maintained at this temperature for 40 min until the system exhibits a pale blue fluorescence. The stirring speed is then reduced to 600 rpm.

[0081] 3. Droplet copolymerization: The remaining 85% pre-emulsified monomer solution and the composite silicone modifier dispersion prepared in step 1 are mixed at a volume ratio of 3:1 to form a mixed droplet solution. This mixed droplet solution and the remaining APS aqueous solution (0.8 parts APS dissolved in 10 parts water) are then added dropwise at a uniform rate to the reaction flask containing the seed emulsion using a peristaltic pump. The dropping rate is controlled so that the total dropping time is approximately 3 hours. After the dropping is complete, the temperature is raised to 84℃ and maintained for 1.5 hours to ensure that the monomer conversion rate is greater than 98%.

[0082] Step 3: Post-treatment and cross-linking The reaction system was cooled to 40℃, and 20% ammonia was slowly added to adjust the pH to 7. The mixture was stirred for 30 min. An ADH aqueous solution (0.8 parts ADH dissolved in 8 parts water) was added, and stirring was continued for 1 h. Finally, the mixture was filtered through a 200-mesh nylon cloth to obtain an aqueous silicone-modified acrylic resin emulsion with a solid content of 35% and a particle size of 120 nm.

[0083] This embodiment provides a seed coating agent, which, by weight percentage, comprises 30 wt% of the above-prepared waterborne silicone-modified acrylic resin emulsion, 8 wt% of the natural modified wax emulsion, 10 wt% of the colorant, 6 wt% of the filler, 4 wt% of the antifreeze, 0.4 wt% of the rheology modifier, 0.1 wt% of the preservative, 0.5 wt% of the plant-derived antibacterial adjuvant, and the remainder being deionized water.

[0084] The natural modified wax emulsion includes carnauba wax modified emulsion and rice bran wax modified emulsion. The natural modified wax emulsion is an emulsion-modified water-based system. It is a conventional water-based emulsion modification. The natural wax is heated to 95°C to melt, a nonionic emulsifier is added, and emulsification is carried out for 60 minutes under stirring. Then, it is homogenized three times under high pressure at 80 MPa to obtain the natural modified wax emulsion.

[0085] The colorant is an aqueous iron oxide red paste.

[0086] The filler is composed of diatomaceous earth, vermiculite and fumed silica in a ratio of 2:1:0.5.

[0087] The antifreeze is a mixture of propylene glycol and polypropylene glycol in a 1:1 ratio.

[0088] The rheology modifier is xanthan gum.

[0089] The preservative is Kathon water-based compound preservative, comprising 5-chloro-2-methyl-4-isothiazolin-3-one (CMI) and 2-methyl-4-isothiazolin-3-one (MI), with a mass ratio of CMI to MI of 3:1.

[0090] The plant-derived antibacterial adjuvant is methyl eugenol.

[0091] Example 2: The difference between this embodiment and Embodiment 1 is that: This embodiment proposes an aqueous silicone-modified acrylic resin, comprising the following components in parts by weight: 35 parts methyl methacrylate (MMA), 40 parts butyl acrylate (BA), 5 parts acrylic acid (AA), 3 parts hydroxypropyl acrylate (HPA), 2 parts nano-SiO2, 3 parts hydroxyl silicone oil, 2 parts silane coupling agent (KH560), 0.8 parts ammonium persulfate (APS), 3 parts emulsifier, 3 parts neutralizer, 1.5 parts low-temperature crosslinking agent (composed of 1 part DAAM and 0.5 parts ADH), and 160 parts deionized water; the emulsifier is a compound of sodium dodecyl sulfate (SDS) and isooctylphenol polyoxyethylene ether (OP10) in a mass ratio of 1:1.2.

[0092] The preparation method is the same as in Example 1.

[0093] This embodiment provides a seed coating agent, which, by mass percentage, comprises 20 wt% of the above-prepared waterborne silicone-modified acrylic resin emulsion, 5 wt% of natural modified wax emulsion, 5 wt% of colorant, 3 wt% of filler, 2 wt% of antifreeze, 0.1 wt% of rheology modifier, 0.2 wt% of preservative, 0.3 wt% of plant-derived antibacterial adjuvant, and the remainder being deionized water.

[0094] The natural modified wax emulsions include beeswax modified emulsions and insect wax modified emulsions.

[0095] The colorant is an aqueous cobalt blue paste.

[0096] The plant-derived antibacterial adjuvant is acetyleugenol. The rest of Example 1 is the same.

[0097] Example 3: The difference between this embodiment and Embodiment 1 is that: This embodiment proposes an aqueous silicone-modified acrylic resin, comprising the following components in parts by weight: 45 parts methyl methacrylate (MMA), 50 parts butyl acrylate (BA), 8 parts acrylic acid (AA), 5 parts hydroxypropyl acrylate (HPA), 4 parts nano-SiO2, 6 parts hydroxyl silicone oil, 3 parts silane coupling agent (KH560), 2.0 parts ammonium persulfate (APS), 5 parts emulsifier, 5 parts neutralizer, 3 parts low-temperature crosslinking agent (composed of 2 parts DAAM and 1 part ADH), and 200 parts deionized water; the emulsifier is a compound of sodium dodecyl sulfate (SDS) and isooctylphenol polyoxyethylene ether (OP10) in a mass ratio of 1:1.5.

[0098] The rest is the same as in Example 1.

[0099] This embodiment provides a seed coating agent, which, by mass percentage, comprises 40 wt% of the above-prepared waterborne silicone-modified acrylic resin emulsion, 10 wt% of the natural modified wax emulsion, 12 wt% of the colorant, 8 wt% of the filler, 5 wt% of the antifreeze, 0.5 wt% of the rheology modifier, 0.2 wt% of the preservative, 0.8 wt% of the plant-derived antibacterial adjuvant, and the remainder being deionized water.

[0100] Example 4: This embodiment provides a method for preparing a water-based silicone-modified acrylic resin specifically for seed coating, which differs from Embodiment 1 in that: Step 1: The ultrasonic dispersion conditions are 300 W power, 25 kHz, 40 min time, and 65℃ temperature.

[0101] Step 2: Preparation of seed emulsion: Nitrogen gas is passed through to remove oxygen for 20 min, the temperature is raised to 75℃, and the reaction is maintained for 30 min.

[0102] Add copolymerization dropwise: Heat to 82℃ and hold for 2 hours.

[0103] The rest is the same as in Example 1, and the prepared waterborne silicone-modified acrylic resin for seed coating has similar effects to that in Example 1.

[0104] Comparative Example 1: The difference between the aqueous silicone-modified acrylic resin emulsion prepared in this comparative example and Example 1 is that the ratio of the core monomer (MMA / BA) deviates from the scope of this invention.

[0105] In step 2, the amount of MMA added is 25 parts, and the amount of BA added is 60 parts. The rest is the same as in Example 1.

[0106] This comparative example provides a seed coating agent, which differs from Example 1 in that it contains the aqueous silicone-modified acrylic resin emulsion prepared in Comparative Example 1, and is otherwise the same as Example 1.

[0107] Comparative Example 2: The difference between the aqueous silicone-modified acrylic resin emulsion prepared in this comparative example and that in Example 1 is that the silicone modification system was not properly treated.

[0108] In step 1, the nano-SiO2 was not pretreated with KH560. The rest was the same as in Example 1.

[0109] This comparative example provides a seed coating agent, which differs from Example 1 in that it contains the aqueous silicone-modified acrylic resin emulsion prepared in Comparative Example 2, and is otherwise the same as Example 1.

[0110] Comparative Example 3: The difference between the aqueous silicone-modified acrylic resin emulsion prepared in this comparative example and Example 1 is that the silicone modification system is missing.

[0111] Step 1 is missing, namely, nano-SiO2, hydroxyl silicone oil, and KH560 are missing. The rest is the same as in Example 1.

[0112] This comparative example provides a seed coating agent, which differs from Example 1 in that it contains the aqueous silicone-modified acrylic resin emulsion prepared in Comparative Example 3, and is otherwise the same as Example 1.

[0113] Comparative Example 4: The difference between the aqueous silicone-modified acrylic resin emulsion prepared in this comparative example and Example 1 is that the emulsifier compounding ratio deviates from the scope of this invention.

[0114] The emulsion agent is a mixture of SDS and OP10 in a 1:1 ratio. The rest is the same as in Example 1.

[0115] Core test results: such as Figure 7 As shown, the emulsion precipitates in layers at room temperature (Example 1 is uniform and stable), and the film formation time is 8 hours at 25°C (Example 1 can form a film quickly in 2 hours).

[0116] Key conclusion: A compounding ratio of 1:1.2 to 1:1.5 is crucial for ensuring emulsion stability and film-forming efficiency; deviation from this ratio will result in the failure of basic performance.

[0117] Comparative Example 5: The difference between the aqueous silicone-modified acrylic resin emulsion prepared in this comparative example and that in Example 1 is that the pH value is adjusted to be slightly acidic (deviating from the range of 7-8).

[0118] The amount of ammonia used was reduced, and the pH of the system was 5-6. Everything else was the same as in Example 1.

[0119] This comparative example provides a seed coating agent, which differs from Example 1 in that it contains the aqueous silicone-modified acrylic resin emulsion prepared in Comparative Example 5, and is otherwise the same as Example 1.

[0120] Comparative Example 6: The difference between the aqueous silicone-modified acrylic resin emulsion prepared in this comparative example and that in Example 1 is that no functional monomer (AA+HPA) was added.

[0121] Remove AA and HPA, and replenish the total monomer amount with MMA+BA. The rest is the same as in Example 1.

[0122] This comparative example provides a seed coating agent, which differs from Example 1 in that it contains the aqueous silicone-modified acrylic resin emulsion prepared in Comparative Example 6, and is otherwise the same as Example 1.

[0123] Results analysis: The seed coating agents prepared in Example 1 and Comparative Example 1 were applied to the coating of corn seeds, such as... Figure 1 As shown, the seed abrasion test results of Example 1 and Comparative Example 1 show that the film shedding rate of Comparative Example 1 is >20%, while the film shedding rate of Example 1 is ≤5%.

[0124] Conclusion: Imbalance in monomer ratio leads to imbalance in the "rigidity-flexibility" of the film layer, proving that 35-45 parts MMA + 40-50 parts BA is the optimal combination that balances abrasion resistance and seed expansion, and is not a conventional choice.

[0125] The seed coating agents prepared in Example 1 and Comparative Example 2 were applied to the coating of corn seeds, such as... Figure 2 As shown, the seed germination rate results of Example 1 and Comparative Example 2 are as follows: the particles on the membrane surface aggregated, the seed germination rate of Comparative Example 2 was 70%, while that of Example 1 was ≥95%.

[0126] Conclusion: KH560 pretreatment is a necessary step to resolve nano-SiO2 agglomeration and ensure biosafety.

[0127] The seed coating agents prepared in Example 1 and Comparative Example 3 were applied to the coating of corn seeds, such as... Figure 3 As shown, the seed abrasion test results of Example 1 and Comparative Example 3 show that the film shedding rate of Comparative Example 3 is >50%, while that of Example 1 is ≤5%.

[0128] Conclusion: Silicon-modified systems are the key to improving the wear resistance of film layers, and conventional acrylic resins cannot achieve this effect.

[0129] The seed coating agents prepared in Example 1 and Comparative Example 5 were applied to the coating of lettuce seeds, such as... Figure 4 As shown, the germination rate of lettuce in Example 1 and Comparative Example 5: Lettuce has biological toxicity to the test material. Example 1 has minimal impact on lettuce seeds. The emulsion gelled after being stored at 50°C for 30 days (Example 1 did not separate).

[0130] Conclusion: pH 7-8 is the optimal range for matching the seed germination environment and ensuring emulsion stability, proving that this parameter is specifically designed rather than arbitrarily adjusted.

[0131] The seed coating agents prepared in Example 1 and Comparative Example 6 were applied to soybean seed coating, such as... Figure 5 As shown, the abrasion test results of Example 1 and Comparative Example 6 show that the film shedding rate of Comparative Example 6 is >50%, while that of Example 1 of the present invention is ≤5%. The coating agent of Comparative Example 6 has no sustained-release effect, while the sustained-release effect of Example 1 can reach 10-30 days.

[0132] Conclusion: AA provides carboxyl groups to enhance adhesion, and HPA regulates crosslinking density to achieve sustained release. The combination of the two is an essential component to ensure the core function of the coating and cannot be replaced by conventional monomer systems.

[0133] like Figure 6As shown, the effect of the slow-release effect of the materials prepared in Example 1 and Comparative Example 6 on soybean growth is evident. It can be seen that the soybean growth in Example 1 is better than that in Comparative Example 6.

[0134] (a) Scope of application The aqueous silicone-modified acrylic resin emulsion prepared by this invention is suitable for coating various crop seeds, including but not limited to wheat, corn, soybean, rice, cotton, and rapeseed. It has no adverse effect on seed germination rate and possesses excellent film-forming properties, adhesion, and sustained-release function.

[0135] (II) Composition of seed coating agent (by mass percentage) 1. Core film-forming component: 20-40 wt% (based on solid content) of the waterborne silicone-modified acrylic resin emulsion prepared in this invention serves as the core film-forming substrate for the coating agent, ensuring the film-forming properties, adhesion, and sustained-release performance of the film layer.

[0136] 2. Natural modified wax emulsion: 5-10 wt%, including one or more of carnauba wax modified emulsion, rice bran wax modified emulsion, beeswax modified emulsion, and insect wax modified emulsion; the natural modified wax emulsion is an emulsified or grafted aqueous system with a solid content of 25-40 wt%, a dispersed particle size ≤1 μm, good compatibility with aqueous silicone modified acrylic resin emulsion and other additives, and no flocculation or stratification. This type of naturally modified wax emulsion is derived from natural sources and is biodegradable. Its core functions are to synergistically improve the abrasion resistance of the coating film (reducing film shedding during transportation and sowing), surface hydrophobicity (reducing the impact of excessive soil moisture on seed soaking), and film density. At the same time, it helps to optimize the slow-release performance of the film and forms a "rigid-flexible" synergistic structure with the core film-forming resin, adapting to the dynamic process of seed water absorption and swelling. It is also low in toxicity and leaves no residue, which is in line with the environmentally friendly design concept. The specific types and compounding ratios are determined according to the crop seed type (such as surface smoothness and particle size) and the application scenario (such as moist soil and dry soil).

[0137] 3. Colorant: 5-12 wt%, using water-based inorganic pigment paste. The inorganic pigment is selected from at least one of the following: iron oxide red, iron oxide yellow, iron oxide brown, titanium dioxide (core component: titanium dioxide), ultramarine (blue), chrome green (core component: chromium trioxide), cobalt blue (core component: cobalt aluminate), carbon black (core component: inorganic carbon black), chrome oxide yellow, and iron blue. The pigment paste is a dispersed water-based system with a solid content of 30-50 wt% and a dispersed particle size ≤1 μm. It has good compatibility with resin emulsions and other additives, and there is no flocculation or sedimentation. It serves as a clear warning color (to distinguish between coated and uncoated seeds and prevent misuse). Because inorganic pigments are chemically stable and non-toxic, they can be slightly decomposed by natural weathering or microorganisms in the soil (or exist stably without polluting the soil), significantly reducing the residual risk of organic colorants and having no adverse effects on soil ecology and crop growth.

[0138] 5. Filler: 3-8 wt%, selected from at least two of the following: natural cellulose powder, microcrystalline cellulose powder, diatomaceous earth, vermiculite, perlite, silica, sepiolite or talc, with a particle size ≤325 mesh. Its porous properties enhance the adhesion of functional ingredients to the seed surface and help improve the slow-release effect.

[0139] 6. Antifreeze: 2-5 wt%, selected from at least one of propylene glycol, polypropylene glycol and its derivatives or glycerol, to prevent the coating agent from freezing at low temperatures and ensure storage and use stability.

[0140] 7. Rheology modifier: 0.1-0.5 wt%, preferably xanthan gum, to adjust the rheological properties of the coating agent and ensure uniform coating of the film during the coating process.

[0141] 8. Preservative: 0.1-0.2wt%, preferably Kathon preservative, to inhibit the growth of microorganisms during the storage of the coating agent and extend the shelf life.

[0142] 9. Plant-derived antibacterial adjuvant: 0.3-0.8 wt%, preferably a modified derivative of eugenol, to help improve the disease control effect.

[0143] 10. Deionized water: Add to 100wt% as a dispersion medium to ensure uniform dispersion of each component and good compatibility with the resin emulsion without compromising the stability of the emulsion.

[0144] (III) Preparation method of seed coating agent 1. Mixing of basic components: Add water-based silicone-modified acrylic resin emulsion, natural modified wax emulsion, colorant, antifreeze, preservative and deionized water to a dispersion vessel equipped with a dispersion plate, turn on the dispersion equipment and disperse at 800-1200 rpm for 5-20 minutes to ensure that the components are initially mixed evenly.

[0145] 2. Rheological property adjustment: Slowly add the rheology modifier (xanthan gum) to the above mixture and continue to disperse for 5-20 minutes at a speed of 800-1200 rpm to ensure that the rheology modifier is completely dissolved and uniformly dispersed. Adjust the viscosity of the system to a suitable coating range (2000-10000 mPa·s, 25℃).

[0146] 3. Post-processing: After dispersion, take samples to test the pH value (should be maintained at 7-8), viscosity and dispersion uniformity of the system. If qualified, filter through 200-mesh nylon cloth to remove any possible impurities and agglomerated particles to obtain the finished seed coating agent.

[0147] (iv) Seed coating application methods 1. Dosage Standard: Adjust the dosage of coating agent according to seed type and size. For grain crop seeds such as corn, wheat, soybean, and rice, the recommended dosage is 2-5 g of finished coating agent per kilogram of seeds; for cash crop and vegetable crop seeds such as cotton and rapeseed, the recommended dosage is 5-15 g per kilogram of seeds.

[0148] 2. Coating process: Add the seeds, the calculated amount of the finished coating agent and the seed coating agent formula to the seed coating machine, and stir and mix at room temperature (20-30℃) for 5-10 minutes to ensure that each seed is evenly coated with a coating film.

[0149] 3. Drying treatment: After coating, place the seeds in a cool, ventilated, and dry place to air dry naturally, or dry them at a low temperature of 30-40℃ until the seed surface is no longer sticky and feels dry to the touch, then they can be stored or sown.

[0150] (vi) Precautions 1. The coating agent should be stirred evenly before use. If slight stratification occurs after long-term standing, it can be used after stirring and testing to ensure that the viscosity and dispersibility are within acceptable limits. This will not affect the coating effect.

[0151] 2. During the preparation and storage of the coating agent, strong acids, strong alkalis or other substances that may damage the stability of the emulsion should be avoided. The ambient temperature should be controlled between 5-40℃, and direct sunlight should be avoided.

[0152] 3. Coated seeds should be stored in a cool, ventilated, and dry place to avoid moisture absorption and mold. The storage environment temperature should be controlled between 0-25℃ and the relative humidity ≤60%.

[0153] 4. For high-value or novel crop seeds, it is recommended to conduct small-scale (100-500 g seeds) coating trials first to verify the germination rate and seedling growth before large-scale application.

[0154] 5. During the coating process and seed drying, avoid high temperatures (above 50°C) and strong light exposure to prevent the coating from cracking or the functional components from decomposing and becoming ineffective.

[0155] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A water-based silicone-modified acrylic resin, characterized in that, It comprises the following components in parts by weight: methyl methacrylate 35-45 parts, butyl acrylate 40-50 parts, acrylic acid 5-8 parts, hydroxypropyl acrylate 3-5 parts, nano-SiO2 2-4 parts, hydroxyl silicone oil 3-6 parts, silane coupling agent 2-3 parts, ammonium persulfate 0.8-2.0 parts, emulsifier 3-5 parts, neutralizer 3-5 parts, low-temperature crosslinking agent 1.5-3 parts, and deionized water 160-200 parts.

2. The waterborne silicone-modified acrylic resin according to claim 1, characterized in that, The emulsifier is a compound of anionic and nonionic emulsifiers in a mass ratio of 1:(1.2-1.5); the anionic emulsifier is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate; the nonionic emulsifier is at least one of octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and Tween-80; the neutralizing agent is at least one of a 20% mass fraction ammonia solution, triethylamine, diethanolamine, dilute sodium bicarbonate solution, and dilute sodium carbonate solution; the low-temperature crosslinking agent is a combination of multiple of diacetone acrylamide, adipate dihydrazide, and malonyl hydrazide.

3. The method for preparing the waterborne silicone-modified acrylic resin according to any one of claims 1-2, characterized in that, Includes the following steps: (1) Pretreatment of silicon modifier: Nano-SiO2 and silane coupling agent are added to deionized water, ultrasonically dispersed, and hydroxyl silicone oil is added to obtain composite silicon modifier dispersion; (2) Seed emulsion polymerization: a. Pre-emulsification: Add the emulsifier to deionized water; then add methyl methacrylate, butyl acrylate, acrylic acid, hydroxypropyl acrylate and diacetone acrylamide to obtain a pre-emulsified monomer solution; b. Preparation of seed emulsion: Add pre-emulsified monomer solution and ammonium persulfate aqueous solution under an inert atmosphere, keep warm, and obtain seed emulsion; c. Adding copolymerization: Mix the pre-emulsified monomer solution with the composite silicon modifier dispersion prepared in step (1) as a mixed adding solution; add the mixed adding solution and ammonium persulfate aqueous solution separately to the reaction flask containing the seed emulsion and heat up; (3) Post-treatment and cross-linking: Cool the reaction system of step (2), add neutralizing agent and adipic acid dihydrazide aqueous solution in sequence, and filter.

4. The preparation method according to claim 3, characterized in that, In step (1), the ultrasonic dispersion power is set to 300W, 25 kHz, and the ultrasonic dispersion time is 40-60 min.

5. The preparation method according to claim 3, characterized in that, In step (a), the emulsifier is a compound of anionic and nonionic emulsifiers with a compounding mass ratio of 1:(1.2-1.5); the anionic emulsifier is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate; the nonionic emulsifier is at least one of octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and Tween-80.

6. The preparation method according to claim 3, characterized in that, In step (b), the inert atmosphere refers to purging with nitrogen to remove oxygen for 20-30 min; the heat preservation method is to raise the temperature to 75-80℃ and keep it at that temperature for 30-40 min; in step (c), the volume ratio of the pre-emulsified monomer liquid to the composite silicon modifier dispersion prepared in step (1) is 2-3:1; the dropping time is 2.5-3 h; the heating method is to raise the temperature to 82-85℃ and keep it at that temperature for 1.5-2 h.

7. The preparation method according to claim 3, characterized in that, In step (3), the temperature is lowered to 40-45℃; the neutralizing agent is at least one of the following: 20% by mass of ammonia solution, triethylamine, diethanolamine, dilute sodium bicarbonate solution, and dilute sodium carbonate solution; the filtration method is to filter with 150-200 mesh nylon cloth.

8. A seed coating agent, characterized in that, By mass percentage, the product comprises 20-40 wt% of an aqueous silicone-modified acrylic resin emulsion prepared by the method described in any one of claims 3-7, 5-10 wt% of a natural modified wax emulsion, 5-12 wt% of a colorant, 3-8 wt% of a filler, 2-5 wt% of an antifreeze, 0.1-0.5 wt% of a rheology modifier, 0.1-0.2 wt% of a preservative, 0.3-0.8 wt% of a plant-derived antibacterial adjuvant, and the remainder being deionized water.

9. The seed coating agent according to claim 8, characterized in that, The natural modified wax emulsion includes one or more of carnauba wax modified emulsion, rice bran wax modified emulsion, beeswax modified emulsion, and insect wax modified emulsion; the natural modified wax emulsion is an emulsified and modified water-based system; the colorant is selected from water-based inorganic pigment paste; the filler is selected from at least two of natural cellulose powder, microcrystalline cellulose powder, diatomaceous earth, vermiculite, perlite, silica, sepiolite, and talc; the antifreeze is selected from at least one of propylene glycol, polypropylene glycol and its derivatives, and glycerol; the rheology modifier is one of xanthan gum, guar gum, hydroxyethyl cellulose, and bentonite; the preservative is at least one of water-based isothiazolinones, benzisothiazolinones, organic bromine compounds, and phenolic ethers; and the plant-derived antibacterial adjuvant is a modified derivative of eugenol.

10. The use of the seed coating agent according to any one of claims 8-9 in seed coating.

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