Acrylic polymer emulsion film-forming agent and preparation method therefor, and seed coating agent

Abstract

Disclosed in the present invention is an acrylic polymer emulsion film-forming agent, which is prepared from the following raw materials in parts by weight: 70-80 parts of a pre-emulsion I, 40-60 parts of a pre-emulsion II, 60-70 parts of an emulsifier solution, 5-10 parts of an initiator solution I, and 10-15 parts of an initiator solution II. In the present invention, trifunctional ethoxylated trimethylolpropane triacrylate and a hard monomer are used as cross-linking monomers to form a network-structure prepolymer I having a relatively high cross-linking density, which can improve the film-forming property of a seed coating agent. The present invention further improves the film-forming property and alkali resistance of the polymers, and therefore the film-forming agent still remains stable in water-rich and alkaline soil and slowly releases active ingredients for seeds. The present invention further improves the film-forming property and alkali resistance of the polymers, and therefore the film-forming agent still remains stable in water-rich and alkaline soil and slowly releases active ingredients for seeds. Prepared coated seeds do not stick together into clumps, thereby facilitating large-scale seeding.

Description

An acrylic polymer emulsion film-forming agent and its preparation method, seed coating agent

[0001] This application claims priority to Chinese patent application 2025100683459, filed on January 16, 2025. The entire contents of the aforementioned Chinese patent application are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of local preservation of plants, specifically to an acrylic polymer emulsion film-forming agent, its preparation method, and the prepared seed coating agent. Background Technology

[0003] Film-forming agents are a crucial component of seed coating agents. They adhere the active ingredients and micronutrients to the seed surface, preventing them from detaching during packaging and transportation. After sowing, they slowly release the active ingredients for seed use. Existing film-forming agents in seed coatings are mostly chitosan, gum arabic, starch, and their derivatives, which have good hydrophilicity and retain water in the soil for seed use. However, they are prone to swelling and hydrolysis in water-rich environments. Swelling is particularly pronounced in alkaline soils. Therefore, developing a film-forming agent for seed coatings that is water-resistant, alkali-resistant, and has good film-forming properties is essential.

[0004] Chinese invention patent CN117303967A discloses a method for preparing a biological seed coating agent and its application. Using sweet potato starch as raw material, potassium hydroxide is added under stirring conditions for gelatinization. Then, potassium acrylate monomer, initiator, crosslinking agent, and surfactant are added. After crosslinking, a starch-based acrylate superabsorbent resin is obtained. After pore-expanding treatment, a film-forming agent is obtained. However, using starch as a raw material, its water resistance is poor and it is easily dissolved in water. Chinese invention patent CN102532398B discloses the use of a polymer compound as a seed coating film-forming agent. The polymer compound containing acrylamide monomers has better film-forming performance and a shorter film-forming time as a seed coating film-forming agent, but its water resistance and alkali resistance are poor. Summary of the Invention

[0005] In order to develop a film-forming agent for seed coating with good water resistance, good alkali resistance and good film-forming properties, the first aspect of the present invention provides an acrylic polymer emulsion film-forming agent, the raw materials for which, by weight, include: 70-80 parts of pre-emulsion I, 40-60 parts of pre-emulsion II, 60-70 parts of emulsifier solution, 5-10 parts of initiating solution I, and 10-15 parts of initiating solution II.

[0006] In a preferred embodiment, the raw materials for preparing the pre-emulsion I include, by weight, 1-5 parts of reactive emulsifier, 3-8 parts of trifunctional acrylate monomer, 20-40 parts of hard monomer, 12-16 parts of soft acrylic monomer I, 1-3 parts of acrylic acid, and 10-30 parts of deionized water.

[0007] In a preferred embodiment, the raw materials for preparing the pre-emulsion I include, by weight, 2.5 parts of reactive emulsifier, 5 parts of trifunctional acrylate monomer, 30 parts of hard monomer, 14 parts of soft acrylic monomer I, 1 part of acrylic acid, and 20 parts of deionized water.

[0008] In a preferred embodiment, the reactive emulsifier is a vinyl polyoxyethylene alkyl ether ammonium sulfate emulsifier.

[0009] In a preferred embodiment, the trifunctional acrylate monomer is ethoxylated trimethylolpropane triacrylate.

[0010] In a preferred embodiment, the hard monomer is styrene; the soft acrylic monomer I is butyl acrylate.

[0011] In a preferred embodiment, the raw materials for preparing the preemulsion II include, by weight, 30-40 parts of acrylate monomer containing a tertiary carbon structure, 12-16 parts of soft acrylic monomer II, and 1-3 parts of acrylic acid.

[0012] In a preferred embodiment, the raw materials for preparing the preemulsion II include, by weight, 35 parts of acrylate monomer containing a tertiary carbon structure, 14 parts of soft acrylic monomer II, and 1 part of acrylic acid.

[0013] In a preferred embodiment, the acrylate monomer containing a tertiary carbon structure is vinyl neodecanoate.

[0014] In a preferred embodiment, the acrylic soft monomer II is butyl acrylate.

[0015] In a preferred embodiment, the acrylate monomer containing a tertiary carbon structure has the structure of Formula I or Formula II, wherein Formula I is... Formula II is In the formula: R1 and R2 are both alkyl groups.

[0016] In a preferred embodiment, the initiating solution I is an initiator solution with a mass fraction of 3-5%, and the initiating solution II is an initiator solution with a mass fraction of 1-3%.

[0017] In a preferred embodiment, both initiation solution I and initiation solution II are aqueous solutions of ammonium persulfate.

[0018] In one preferred embodiment, the initiation solution I is 0.2g of ammonium persulfate dissolved in 5g of deionized water; in another preferred embodiment, the initiation solution II is 0.3g of ammonium persulfate dissolved in 12g of deionized water.

[0019] In a preferred embodiment, the mass concentration of the emulsifier solution is 0.5-1%.

[0020] In a preferred embodiment, the emulsifier solution is an aqueous solution of vinyl polyoxyethylene alkyl ether ammonium sulfate.

[0021] In a preferred embodiment, the emulsifier solution is 0.5g of vinyl polyoxyethylene alkyl ether ammonium sulfate dissolved in 60g of deionized water.

[0022] During the experiment, the inventors discovered that using trifunctional ethoxylated trimethylolpropane triacrylate and hard monomers as crosslinking monomers to form a network structure prepolymer I with high crosslinking density can improve the film-forming properties of the seed coating agent. This is because the high-functionality ethoxylated trimethylolpropane triacrylate has high reactivity, resulting in a crosslinking network with high crosslinking density and a certain degree of toughness, enabling rapid film formation on the seed surface. The inventors further discovered that acrylate monomers containing tertiary carbon structures and soft monomers can form linear prepolymer II. The ester groups of prepolymer II are linked to tertiary carbon structures, providing significant steric hindrance. Under alkaline conditions, this protects the ester groups, reduces hydrolysis rate, and improves alkali resistance. Linear prepolymer II can interpenetrate and swell with prepolymer I, further improving the film-forming properties and alkali resistance of the polymer. Furthermore, the use of reactive surfactants during the interpenetrating polymerization of linear prepolymer II and prepolymer I further improves the water resistance of the seed coating agent, allowing it to remain stable in water-rich, alkaline soils and slowly release active ingredients for seed use.

[0023] A second aspect of the present invention provides a method for preparing an acrylic polymer emulsion film-forming agent, comprising the following steps:

[0024] S1. Mix the reactive emulsifier with deionized water and stir for 10-30 minutes. Add the trifunctional acrylate monomer, hard monomer, soft acrylic monomer I, and acrylic acid and stir for 20-30 minutes to obtain pre-emulsion I.

[0025] S2 involves mixing and stirring tertiary carbon-structured acrylate monomers, soft acrylic monomer II, and acrylic acid for 20-30 minutes to form pre-emulsion II.

[0026] S3 is used to prepare initiation solution I and initiation solution II;

[0027] S4 prepares an emulsifier solution in a reactor;

[0028] S5 heats the reactor to 80-85℃, adds initiation solution I, stirs for 3-5 minutes, and simultaneously adds pre-emulsion I and 50wt% initiation solution II dropwise for 1-2 hours, and keeps warm for 1-3 hours; then adds pre-emulsion II and the remaining initiation solution II dropwise for 1-2 hours, keeps warm for 1-3 hours, and then carries out the elimination reaction, cools down to below 50℃ to neutralize to obtain acrylic polymer emulsion film-forming agent.

[0029] In a preferred embodiment, the elimination reaction is carried out by using tert-butyl hydroperoxide or sodium bisulfite to eliminate residual monomers in the system, and the amount of tert-butyl hydroperoxide or sodium bisulfite added is less than 1 wt‰ of the total system. In this invention, ammonia water is used to neutralize the pH to 6.5-7.5 to obtain an acrylic polymer emulsion film-forming agent.

[0030] A third aspect of the present invention provides a seed coating agent, the raw materials of which include the above-mentioned acrylic polymer emulsion film-forming agent.

[0031] In a preferred embodiment, the raw materials for preparing the seed coating agent, by weight percentage, include: 2-9% acrylic polymer emulsion film-forming agent, 0.2-5% wetting agent, 0.2-5% dispersant, 0.1-0.3% suspending agent, 0-2% cellulose ether, 0.1-0.3% defoamer, 0.5-2% leveling agent, 0.1-1% antifreeze agent, 20-25% technical grade component, 0.1-4% warning color, and water to 100%.

[0032] In a preferred embodiment, the active ingredient is selected from one or more combinations of thiamethoxam, tebuconazole, and pyraclostrobin.

[0033] In a preferred embodiment, the wetting agent is selected from one or more combinations of siloxane-based twin-structure surfactants or nonionic organic silicone-free defoamers.

[0034] In a preferred embodiment, the dispersant is an anionic dispersant; more preferably, the anionic dispersant is polyacrylate and / or polycarboxylate.

[0035] In a preferred embodiment, the wetting agent is a siloxane wetting agent.

[0036] In a preferred embodiment, the suspending agent is selected from at least one of xanthan gum, bentonite, attapulgite, magnesium aluminum silicate, and sepiolite; more preferably, the suspending agent is xanthan gum.

[0037] In a preferred embodiment, the cellulose ether is selected from at least one of carboxymethyl cellulose ether and hydroxyethyl cellulose ether; more preferably, the cellulose ether is hydroxyethyl cellulose.

[0038] In a preferred embodiment, the defoamer is selected from mineral oil defoamers and organosilicon defoamers; more preferably, the defoamer is a mineral oil defoamer.

[0039] In a preferred embodiment, the leveling agent is a polyurethane leveling agent.

[0040] In a preferred embodiment, the antifreeze agent is ethylene glycol.

[0041] A fourth aspect of the present invention provides a method for preparing a seed coating agent, comprising the following steps:

[0042] S1 After mixing water, wetting agent, dispersant and defoamer evenly, add suspending agent and cellulose ether in sequence and stir for 5-20 minutes;

[0043] S2 is then added sequentially as an acrylic polymer emulsion film-forming agent, active ingredient, leveling agent, antifreeze agent, and warning color, and mixed thoroughly to obtain the seed coating agent.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The acrylic polymer emulsion film-forming agent of the present invention uses trifunctional ethoxylated trimethylolpropane triacrylate and hard monomer as crosslinking monomers to form a network structure prepolymer I with high crosslinking density, which can improve the film-forming properties of seed coating agents.

[0046] (2) The acrylic polymer emulsion film-forming agent of the present invention contains acrylate monomers with tertiary carbon structures and soft monomers that can form linear prepolymer II. In an alkaline environment, it can protect the ester groups, reduce the hydrolysis rate, and improve alkali resistance.

[0047] (3) The acrylic polymer emulsion film-forming agent of the present invention has a linear prepolymer II that can interpenetrate and swell with prepolymer I, which further improves the film-forming properties and alkali resistance of the polymer, so that it can still exist stably in water-rich and alkaline soils and slowly release active ingredients for seed use.

[0048] (4) The acrylic polymer emulsion film-forming agent of the present invention is environmentally friendly and does not affect the normal germination of seeds; it has strong water resistance and will not be dissolved by water; and it has stable compatibility with each component.

[0049] (5) The acrylic polymer emulsion film-forming agent of the present invention does not stick together after seed coating treatment, which facilitates large-scale sowing. Detailed Implementation

[0050] Example 1

[0051] An acrylic polymer emulsion film-forming agent, the raw materials for preparation include, by weight: 72.5 parts of preemulsion I, 50 parts of preemulsion II, 60.5 parts of emulsifier solution, 5.2 parts of initiating solution I, and 12.3 parts of initiating solution II.

[0052] The raw materials for preparing the pre-emulsion I include, by weight, 2.5 parts of reactive emulsifier, 5 parts of trifunctional acrylate monomer, 30 parts of hard monomer, 14 parts of soft acrylic monomer I, 1 part of acrylic acid, and 20 parts of deionized water.

[0053] The reactive emulsifier is a vinyl polyoxyethylene alkyl ether ammonium sulfate emulsifier, purchased from Adico, brand name SR10.

[0054] The trifunctional acrylate monomer is ethoxylated trimethylolpropane triacrylate.

[0055] The hard monomer is styrene; the soft acrylic monomer I is butyl acrylate.

[0056] The raw materials for preparing the preemulsion II include, by weight, 35 parts of acrylate monomer containing tertiary carbon structure, 14 parts of soft acrylic monomer II, and 1 part of acrylic acid.

[0057] The acrylate monomer containing a tertiary carbon structure is vinyl neodecanoate. The soft acrylate monomer II is butyl acrylate.

[0058] Both initiation solution I and initiation solution II are aqueous solutions of ammonium persulfate.

[0059] A method for preparing an acrylic polymer emulsion film-forming agent includes the following steps:

[0060] S1. The reactive emulsifier is mixed with deionized water and stirred for 20 min. Trifunctional acrylate monomer, hard monomer, soft acrylic monomer I, and acrylic acid are added and stirred for 25 min to obtain pre-emulsion I.

[0061] S2: Mix and stir tertiary carbon structure acrylate monomer, soft acrylic monomer II, and acrylic acid for 25 min to form pre-emulsion II;

[0062] S3 is prepared by dissolving 0.2 g of ammonium persulfate in 5 g of deionized water to form initiation solution I; and by dissolving 0.3 g of ammonium persulfate in 12 g of deionized water to form initiation solution II.

[0063] S4 prepares an emulsifier solution in a reactor by dissolving 0.5g of vinyl polyoxyethylene alkyl ether ammonium sulfate in 60g of deionized water;

[0064] S5 heats the reactor to 80-85℃, adds initiation solution I, stirs for 5 min, and simultaneously adds preemulsion I and 50 wt% initiation solution II dropwise for 1 h, and keeps warm for 2 h; then adds preemulsion II and the remaining initiation solution II dropwise for 1 h, keeps warm for 2 h, and then carries out the elimination reaction, cools down to below 50℃ to neutralize and obtain acrylic polymer emulsion film-forming agent.

[0065] The elimination reaction involves using tert-butyl hydrogen peroxide to eliminate residual monomers in the system, with the amount of tert-butyl hydrogen peroxide added being less than 1 wt‰ of the total system content. In this invention, ammonia is used to neutralize the pH to 6.5-7.5 to obtain an acrylic polymer emulsion film-forming agent.

[0066] Example

[0067] A seed coating agent, wherein the raw materials for preparing the seed coating agent are shown in Table 1 by weight percentage.

[0068] Table 1

[0069] The dispersant SN-5027 was purchased from Sannopco; the wetting agent... Twin 4100 was purchased from Evonik, and the wetting agent... 500 was purchased from Evonik Industries, Inc.; the cellulose ether 250HBR was purchased from Yakulong. The defoamer SN-154 was purchased from Sanopco; the leveling agent RM2020 was purchased from Rohm and Haas. The PVC was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., brand name Poly(vinyl alcohol) 1788; and the CMC was purchased from Hebei Hengju Chemical Co., Ltd., brand name CMC-HV.

[0070] A method for preparing a seed coating agent includes the following steps:

[0071] S1 After mixing water, wetting agent, dispersant and defoamer evenly, add suspending agent and cellulose ether in sequence and stir for 10 minutes;

[0072] S2 is then added sequentially as an acrylic polymer emulsion film-forming agent, active ingredient, leveling agent, antifreeze agent, and warning color, and mixed thoroughly to obtain the seed coating agent.

[0073] Performance testing

[0074] 1. Film-forming property test

[0075] Weigh 0.4g of seed coating agent and cast it onto a 2.5cm×7.6cm glass slide to form a film. Observe the film-forming properties at 23±2℃ and 50±5% relative humidity. The film-forming agent should be free of cracks after drying.

[0076] 2. Swelling test

[0077] Weigh 0.4g of seed coating agent and cast it onto a 2cm×10cm glass slide to form a film. After drying, weigh the film to obtain the dry film weight. After immersing the film in water for 3 hours, weigh the film again to obtain the wet film weight.

[0078] Swelling property Qw = (W - W0) / W0 × 100%

[0079] W0: Dry film weight (g); W: Wet film weight (g).

[0080] 3. Solubility

[0081] Weigh 0.4g of seed coating agent and cast it onto a 2cm×10cm glass slide to form a film. Dry it to constant weight, which is M1. Soak it in distilled water for 48h, take it out and dry it to constant weight, which is M2. Calculate the solubility of the film-forming agent.

[0082] Solubility (%) = (M1-M2) / (M1-M0) x 100%

[0083] M0: Slide mass; M1: Mass of slide and drying film-forming agent;

[0084] M2: Total mass of glass slide and film-forming agent that has been soaked in water for 48 hours and dried.

[0085] 4. Initial drying adhesion

[0086] After the seed coating agent was applied to the seeds at the same ratio, the seeds were allowed to dry for 10 minutes, and the degree of direct adhesion was observed.

[0087] 5. Thermal storage stability

[0088] The seed coating agent was packaged in a sealed container and stored in a 55℃ oven for 7 days. After the storage period, the container was removed and left to stand at (23±2)℃ for 4 hours. The changes in the state of the seed coating agent inside the container were then observed.

[0089] 6. Alkali resistance

[0090] Prepare a saturated calcium hydroxide solution at 23±2℃ and 50±5% relative humidity. After standing for 24 hours, take the supernatant for later use. Cast 0.4g of seed coating agent onto a 2cm×10cm glass slide to form a film. After drying to constant weight, immerse the film in the supernatant. After 24 hours, remove the film and observe the state of the film-forming agent on the glass slide.

[0091] The test results are shown in Table 2.

[0092] Table 2

[0093] Swelling property: Compared with Comparative Examples 2 and 3, the swelling property of Examples 2-4 is limited, indicating that Examples 2-4 have low hydrophilicity and good water resistance; the swelling property of Comparative Example 1 is negative, which is due to the loss of polyvinyl alcohol in water;

[0094] Solubility: Examples 2-4 have essentially zero solubility and excellent water resistance; Comparative Examples 1-3 have nearly 100% solubility and no water resistance.

[0095] Initial drying adhesion: Since the film-forming agent of Examples 2-4 has a Tg of 10-15℃, there is no abnormality in the initial drying adhesion of Examples 2-4, while the seeds of Comparative Examples 1-3 all exhibited clumping.

Claims

1. An acrylic polymer emulsion film-forming agent, characterized in that, The raw materials for preparation include, by weight: 70-80 parts of preemulsion I, 40-60 parts of preemulsion II, 60-70 parts of emulsifier solution, 5-10 parts of initiating solution I, and 10-15 parts of initiating solution II.

2. The acrylic polymer emulsion film-forming agent according to claim 1, characterized in that, The raw materials for preparing the pre-emulsion I include, by weight, 1-5 parts of reactive emulsifier, 3-8 parts of trifunctional acrylate monomer, 20-40 parts of hard monomer, 12-16 parts of soft acrylic monomer I, 1-3 parts of acrylic acid, and 10-30 parts of deionized water.

3. The acrylic polymer emulsion film-forming agent according to claim 2, characterized in that, The raw materials for preparing the preemulsion II include, by weight, 30-40 parts of acrylate monomer containing tertiary carbon structure, 12-16 parts of soft acrylic acid monomer II, and 1-3 parts of acrylic acid.

4. The acrylic polymer emulsion film-forming agent according to claim 3, characterized in that, The acrylate monomer containing a tertiary carbon structure has the structure of formula I or formula II, where formula I is... Formula II is In the formula: R1 and R2 are both alkyl groups.

5. The acrylic polymer emulsion film-forming agent according to claim 3, characterized in that, The initiating solution I is an initiator solution with a mass fraction of 3-5%, and the initiating solution II is an initiator solution with a mass fraction of 1-3%.

6. A method for preparing an acrylic polymer emulsion film-forming agent according to claim 5, characterized in that, Includes the following steps: S1. Mix the reactive emulsifier with deionized water and stir for 10-30 minutes. Add the trifunctional acrylate monomer, hard monomer, soft acrylic monomer I, and acrylic acid and stir for 20-30 minutes to obtain pre-emulsion I. S2 involves mixing and stirring tertiary carbon-structured acrylate monomers, soft acrylic monomer II, and acrylic acid for 20-30 minutes to form pre-emulsion II. S3 is used to prepare initiation solution I and initiation solution II; S4 prepares an emulsifier solution in a reactor; S5 Heat the reactor to 80-85℃, add initiation solution I, stir for 3-5 minutes, and simultaneously add pre-emulsion I and 50wt% initiation solution II dropwise for 1-2 hours, and keep warm for 1-3 hours; Then, pre-emulsion II and the remaining initiating solution II are added dropwise for 1-2 hours, kept warm for 1-3 hours, and then an elimination reaction is carried out. The mixture is then cooled to below 50°C and neutralized to obtain an acrylic polymer emulsion film-forming agent.

7. A seed coating agent, characterized in that, The raw materials for preparation include the acrylic polymer emulsion film-forming agent according to any one of claims 1-5.

8. The seed coating agent according to claim 7, characterized in that, The raw materials for preparing the seed coating agent, by weight percentage, include: 2-9% acrylic polymer emulsion film-forming agent, 0.2-5% wetting agent, 0.2-5% dispersant, 0.1-0.3% suspending agent, 0-2% cellulose ether, 0.1-0.3% defoamer, 0.5-2% leveling agent, 0.1-1% antifreeze agent, 20-25% technical grade component, 0.1-4% warning color, and water to 100%.

9. The seed coating agent according to claim 8, characterized in that, The active ingredient is selected from one or more of thiamethoxam, tebuconazole, and pyraclostrobin.

10. A method for preparing a seed coating agent according to any one of claims 8-9, characterized in that, Includes the following steps: S1 After mixing water, wetting agent, dispersant and defoamer evenly, add suspending agent and cellulose ether in sequence and stir for 5-20 minutes; S2 is then added sequentially as an acrylic polymer emulsion film-forming agent, active ingredient, leveling agent, antifreeze agent, and warning color, and mixed thoroughly to obtain the seed coating agent.

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