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

Abstract

The invention discloses an acrylic polymer emulsion film-forming agent, which is prepared from the following raw materials in parts by weight: 70 to 80 parts of pre-emulsion I, 40 to 60 parts of pre-emulsion II, 60 to 70 parts of emulsifier solution, 5 to 10 parts of initiation solution I and 10 to 15 parts of initiation solution II. The trifunctional ethoxylated trimethylolpropane triacrylate and the hard monomer are used as crosslinking monomers to form a network structure prepolymer I with relatively high crosslinking density, so that the film-forming property of the seed coating agent can be improved. And the acrylate monomer containing the tertiary carbon structure and the soft monomer can form a linear prepolymer II, and in an alkaline environment, ester groups can be protected, the hydrolysis rate can be reduced, and the alkali resistance can be improved. The film-forming property and alkali resistance of the polymer are further improved, so that the polymer can still stably exist in water-rich and alkaline soil, and active ingredients are slowly released for seeds to use. And the prepared seeds are not adhered and clustered after being coated, so that large-scale seeding is facilitated.

Description

Technical Field

[0001] The invention relates to the field of local preservation of plants, and in particular to an acrylic polymer emulsion film-forming agent, a preparation method thereof and a seed coating agent prepared thereby. Background Art

[0002] Film-forming agents are an important component of seed coating agents. They can adhere the original drug and micro-fertilizer to the surface of the seeds, so that the components do not fall off during packaging and transportation. After sowing, the active ingredients are slowly released for seeds to use. The film-forming agents in existing coating agents are mostly chitosan, gum arabic, starch and its derivatives, etc., which have good hydrophilicity and enrich water in the soil for seeds to use. However, they are easy to swell and hydrolyze in a water-rich environment. Especially in alkaline soils, swelling problems are more likely to occur. Therefore, it is very important to develop a film-forming agent for seed coating agents with good water resistance, good alkali resistance and good film-forming properties.

[0003] Chinese invention patent CN117303967A discloses a preparation method and application of a biological seed coating agent, using sweet potato starch as raw material, adding potassium hydroxide to gelatinize under stirring conditions, then adding potassium acrylate monomer, initiator, crosslinking agent and surfactant, crosslinking to obtain starch-based acrylate superabsorbent resin, and after pore expansion treatment, a film-forming agent is obtained, but starch is used as raw material, and the water resistance is poor and it is easily destroyed by water. Chinese invention patent CN102532398B discloses the use of a polymer compound as a seed coating film-forming agent, using a polymer compound containing acrylamide monomers as a seed coating film-forming agent, having better film-forming properties and shorter film-forming time, but poor water resistance and alkali resistance. Summary of the invention

[0004] In order to develop a film-forming agent for seed coating agents 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, and the preparation raw materials include, by weight: 70-80 parts of pre-emulsion I, 40-60 parts of pre-emulsion II, 60-70 parts of emulsifier solution, 5-10 parts of initiator solution I, and 10-15 parts of initiator solution II.

[0005] As 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 acrylic soft monomer I, 1-3 parts of acrylic acid, and 10-30 parts of deionized water.

[0006] As 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 acrylic soft monomer I, 1 part of acrylic acid, and 20 parts of deionized water.

[0007] As a preferred embodiment, the reactive emulsifier is a vinyl polyoxyethylene alkyl ether ammonium sulfate emulsifier.

[0008] As a preferred embodiment, the trifunctional acrylate monomer is ethoxylated trimethylolpropane triacrylate.

[0009] As a preferred embodiment, the hard monomer is styrene; and the acrylic soft monomer I is butyl acrylate.

[0010] As a preferred embodiment, the raw materials for preparing the pre-emulsion II include, by weight, 30-40 parts of acrylate monomers containing tertiary carbon structures, 12-16 parts of acrylic soft monomers II, and 1-3 parts of acrylic acid.

[0011] As a preferred embodiment, the raw materials for preparing the pre-emulsion II include, by weight, 35 parts of acrylate monomers containing tertiary carbon structures, 14 parts of acrylic soft monomers II, and 1 part of acrylic acid.

[0012] As a preferred embodiment, the tertiary carbon structure-containing acrylic acid ester monomer is vinyl neodecanoate.

[0013] As a preferred embodiment, the acrylic soft monomer II is butyl acrylate.

[0014] As a preferred embodiment, the structure of the tertiary carbon structure-containing acrylic ester monomer is Formula I or Formula II, where Formula I is Formula II is In the formula: R1 and R2 are both alkyl groups.

[0015] As a preferred embodiment, the initiator solution I is an initiator solution with a mass fraction of 3-5%, and the initiator solution II is an initiator solution with a mass fraction of 1-3%.

[0016] As a preferred embodiment, the initiating solution I and the initiating solution II are both aqueous solutions of ammonium persulfate.

[0017] As a preferred embodiment, the initiating solution I is 0.2 g of ammonium persulfate dissolved in 5 g of deionized water; as a preferred embodiment, the initiating solution II is 0.3 g of ammonium persulfate dissolved in 12 g of deionized water.

[0018] As a preferred embodiment, the mass concentration of the emulsifier solution is 0.5-1%.

[0019] As a preferred embodiment, the emulsifier solution is an aqueous solution of vinyl polyoxyethylene alkyl ether ammonium sulfate.

[0020] As a preferred embodiment, the emulsifier solution is 0.5 g of vinyl polyoxyethylene alkyl ether ammonium sulfate dissolved in 60 g of deionized water.

[0021] The inventors found in the experimental process that the use of trifunctional ethoxylated trimethylolpropane triacrylate and hard monomer as cross-linking monomers to form a network structure prepolymer I with a high cross-linking density can improve the film-forming property of the seed coating agent. The reason is that the high-functionality ethoxylated trimethylolpropane triacrylate has a high reaction activity, the cross-linking network formed has a high cross-linking density, and has a certain toughness, and can quickly form a film on the seed surface. The inventors further found that the acrylate monomer containing a tertiary carbon structure and the soft monomer can form a linear prepolymer II. The ester group of prepolymer II connects the tertiary carbon structure and has a large steric hindrance. Under alkaline conditions, it can protect the ester group, reduce the hydrolysis rate, and improve the alkali resistance. The linear prepolymer II can interpenetrate and swell with the prepolymer I, further improving the film-forming property and alkali resistance of the polymer. In addition, the use of a reactive surfactant reaction in the interpenetrating polymerization process of the linear prepolymer II and the prepolymer I further improves the water resistance of the seed coating agent, so that it can still exist stably in water-rich, alkaline soils, and slowly release active ingredients for seeds.

[0022] The second aspect of the present invention provides a method for preparing an acrylic polymer emulsion film-forming agent, comprising the following steps:

[0023] S1: Mix the reactive emulsifier and deionized water and stir for 10-30 minutes, add the trifunctional acrylate monomer, hard monomer, acrylic soft monomer I, and acrylic acid and stir for 20-30 minutes to obtain pre-emulsion I;

[0024] S2: tertiary carbon structure acrylate monomer, acrylic soft monomer II, and acrylic acid are mixed and stirred for 20-30 minutes to prepare pre-emulsion II;

[0025] S3 prepares initiating solution I and initiating solution II;

[0026] S4 prepares an emulsifier solution in a reactor;

[0027] S5: Heat the reactor to 80-85°C, add initiator solution I, stir for 3-5 minutes, and simultaneously drip pre-emulsion I and 50wt% of initiator solution II, drip for 1-2 hours, and keep warm for 1-3 hours; then drip pre-emulsion II and the remaining initiator solution II, drip for 1-2 hours, and keep warm for 1-3 hours, then carry out elimination reaction, cool to below 50°C and neutralize to neutral to obtain an acrylic polymer emulsion film-forming agent.

[0028] As a preferred embodiment, the elimination reaction is to use tert-butyl hydroperoxide or sodium bisulfite to eliminate residual monomers in the system, and the addition amount of tert-butyl hydroperoxide or sodium bisulfite is less than 1wt‰ of the entire system; the present invention uses ammonia water to neutralize the pH to 6.5-7.5 to obtain an acrylic polymer emulsion film-forming agent.

[0029] The third aspect of the present invention provides a seed coating agent, the raw materials for preparing the agent include the acrylic polymer emulsion film-forming agent mentioned above.

[0030] As a preferred embodiment, the raw materials for preparing the seed coating agent include, by weight percentage: 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% defoaming agent, 0.5-2% leveling agent, 0.1-1% antifreeze agent, 20-25% original drug component, 0.1-4% warning color, and water is supplemented to 100%.

[0031] As a preferred embodiment, the technical component is selected from one or more combinations of thiamethoxam, metconazole, and myclobutanil.

[0032] As a preferred embodiment, the wetting agent is selected from a combination of one or more of a siloxane-based gemini surfactant or a nonionic organic silicon-free defoaming agent.

[0033] As a preferred embodiment, the dispersant is an anionic dispersant; more preferably, the anionic dispersant is a polyacrylate and / or a polycarboxylate.

[0034] As a preferred embodiment, the wetting agent is a silicone wetting agent.

[0035] As 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.

[0036] As 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.

[0037] As a preferred embodiment, the defoaming agent is selected from a mineral oil defoaming agent and a silicone defoaming agent. More preferably, the defoaming agent is a mineral oil defoaming agent.

[0038] As a preferred embodiment, the leveling agent is a polyurethane leveling agent.

[0039] As a preferred embodiment, the antifreeze agent is ethylene glycol.

[0040] A fourth aspect of the present invention provides a method for preparing a seed coating agent, comprising the following steps:

[0041] S1: Mix water, wetting agent, dispersant and defoamer evenly, then add suspending agent and cellulose ether in turn and stir for 5-20 minutes;

[0042] S2 then adds acrylic polymer emulsion film-forming agent, technical component, leveling agent, antifreeze agent and warning color in sequence and mixes evenly to obtain seed coating agent.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The acrylic polymer emulsion film-forming agent of the present invention uses trifunctional ethoxylated trimethylolpropane triacrylate and a hard monomer as cross-linking monomers to form a network structure prepolymer I with a high cross-linking density, which can improve the film-forming property of the seed coating agent.

[0045] (2) The acrylic polymer emulsion film-forming agent of the present invention contains tertiary carbon structure acrylic ester monomers and soft monomers to form linear prepolymer II, which can protect the ester group in an alkaline environment, reduce the hydrolysis rate, and improve the alkali resistance.

[0046] (3) The acrylic polymer emulsion film-forming agent of the present invention, the linear prepolymer II can interpenetrate and swell with the prepolymer I, further improving the film-forming property and alkali resistance of the polymer, so that it can still exist stably in water-rich, alkaline soil and slowly release the active ingredient for seed use.

[0047] (4) The acrylic polymer emulsion film-forming agent of the present invention is harmless to the environment and does not affect the normal germination of seeds; it has strong water resistance and will not be destroyed by water; and it has stable compatibility with various components.

[0048] (5) The acrylic polymer emulsion film-forming agent of the present invention does not adhere to the seeds after being coated, which is convenient for large-scale sowing. DETAILED DESCRIPTION

[0049] Example 1

[0050] An acrylic polymer emulsion film-forming agent is prepared by raw materials including, by weight: 72.5 parts of pre-emulsion I, 50 parts of pre-emulsion II, 60.5 parts of emulsifier solution, 5.2 parts of initiator solution I, and 12.3 parts of initiator solution II.

[0051] 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 acrylic soft monomer I, 1 part of acrylic acid, and 20 parts of deionized water.

[0052] The reactive emulsifier is vinyl polyoxyethylene alkyl ether ammonium sulfate emulsifier, purchased from Aidico, brand SR10.

[0053] The trifunctional acrylate monomer is ethoxylated trimethylolpropane triacrylate.

[0054] The hard monomer is styrene; the acrylic soft monomer I is butyl acrylate.

[0055] The raw materials for preparing the pre-emulsion II include, by weight, 35 parts of tertiary carbon structure-containing acrylic acid ester monomers, 14 parts of acrylic acid soft monomer II, and 1 part of acrylic acid.

[0056] The acrylic acid ester monomer containing a tertiary carbon structure is vinyl neodecanoate. The acrylic acid soft monomer II is butyl acrylate.

[0057] The initiating solution I and the initiating solution II are both aqueous solutions of ammonium persulfate.

[0058] A method for preparing an acrylic polymer emulsion film-forming agent comprises the following steps:

[0059] S1: Mix the reactive emulsifier and deionized water and stir for 20 minutes, add the trifunctional acrylate monomer, hard monomer, acrylic acid soft monomer I, and acrylic acid and stir for 25 minutes to obtain pre-emulsion I;

[0060] S2: tertiary carbon structure acrylate monomer, acrylic soft monomer II, and acrylic acid are mixed and stirred for 25 minutes to prepare pre-emulsion II;

[0061] S3: Prepare initiator solution I by dissolving 0.2 g of ammonium persulfate in 5 g of deionized water; initiator solution II by dissolving 0.3 g of ammonium persulfate in 12 g of deionized water;

[0062] S4: preparing an emulsifier solution in a reactor by dissolving 0.5 g of vinyl polyoxyethylene alkyl ether ammonium sulfate in 60 g of deionized water;

[0063] S5: Heat the reactor to 80-85°C, add initiator solution I, stir for 5 minutes, and simultaneously drip pre-emulsion I and 50wt% of initiator solution II, drip for 1 hour, and keep warm for 2 hours; then drip pre-emulsion II and the remaining initiator solution II, drip for 1 hour, and keep warm for 2 hours, then carry out elimination reaction, cool to below 50°C and neutralize to obtain an acrylic polymer emulsion film-forming agent.

[0064] The elimination reaction uses tert-butyl hydroperoxide to eliminate residual monomers in the system, and the amount of tert-butyl hydroperoxide added is less than 1wt‰ of the entire system; the present invention uses ammonia water to neutralize the pH to 6.5-7.5 to obtain an acrylic polymer emulsion film-forming agent.

[0065] Example

[0066] A seed coating agent, the raw materials for preparing the seed coating agent are expressed in percentage by weight, as shown in Table 1.

[0067] Table 1

[0068]

[0069]

[0070] The dispersant SN-5027 was purchased from San Nopco; the wetting agent Twin 4100 was purchased from Evonik, the wetting agent 500 was purchased from Evonik, the cellulose ether 250HBR was purchased from Aqualon, the defoamer SN-154 was purchased from San Nopco, and the leveling agent RM2020 was purchased from Rohm and Haas. The PVC was purchased from Shanghai MacLean Biochemical Technology Co., Ltd., with the brand name Poly (vinyl alcohol) 1788, and the CMC was purchased from Hebei Hengju Chemical Co., Ltd., with the brand name CMC-HV.

[0071] A method for preparing a seed coating agent comprises the following steps:

[0072] S1: Mix water, wetting agent, dispersant and defoamer evenly, then add suspending agent and cellulose ether in turn and stir for 10 minutes;

[0073] S2 then adds acrylic polymer emulsion film-forming agent, technical component, leveling agent, antifreeze agent and warning color in sequence and mixes evenly to obtain seed coating agent.

[0074] Performance Testing

[0075] 1. Film forming test

[0076] Weigh 0.4 g of seed coating agent and cast it onto a 2.5 cm × 7.6 cm glass slide to form a film. Observe the film-forming property at 23±2°C and 50±5% relative humidity. There should be no cracks after the film-forming agent dries.

[0077] 2. Swelling test

[0078] Weigh 0.4 g of seed coating agent and cast it on a 2 cm × 10 cm glass slide to form a film. After drying, weigh it, which is the dry film weight; soak it in water for 3 hours and weigh it again, which is the wet film weight.

[0079] Swelling Q w =(W-W0) / W0×100%

[0080] W0: dry film weight (g); W: wet film weight (g).

[0081] 3. Solubility

[0082] Weigh 0.4 g of seed coating agent and cast it on a 2 cm × 10 cm glass slide to form a film, dry it to constant weight, which is M1; soak it in distilled water for 48 hours, take it out and dry it to constant weight, which is M2, and calculate the solubility of the film-forming agent.

[0083] Solubility (%) = (M1-M2) / (M1-M0) x 100%

[0084] M0: mass of glass slide; M1: mass of glass slide and dry film-forming agent;

[0085] M2: The total mass of the glass slide and the dried film-forming agent after immersion in water for 48 hours.

[0086] 4. Initial dry adhesion

[0087] After the seed coating agent is coated on the seeds at the same seed-drug ratio and initially dried for 10 minutes, the direct adhesion of the seeds is observed.

[0088] 5. Thermal storage stability

[0089] The seed coating agent was packaged in a sealed container and heat-stored in a 55°C oven for 7 days. After the heat storage, the seed coating agent was taken out and placed at (23±2)°C. After 4 hours, the state changes in the seed coating agent tank were observed.

[0090] 6. Alkali resistance

[0091] A saturated solution of calcium hydroxide was prepared at 23±2°C and 50±5% relative humidity. After standing for 24 hours, the supernatant was collected for later use. 0.4 g of the seed coating agent was cast into a film on a 2cm×10cm glass slide, dried to constant weight, and then immersed in the supernatant. After 24 hours, the film-forming agent was taken out and the state of the film-forming agent on the glass slide was observed.

[0092] The test results are shown in Table 2.

[0093] Table 2

[0094]

[0095]

[0096] Swelling property: Compared with Comparative Example 2 and Comparative Example 3, the swelling property of Examples 2-4 is limited, indicating that Examples 2-4 are not highly hydrophilic and have good water resistance; the swelling property of Comparative Example 1 is negative, which is caused by the dissolution of polyvinyl alcohol in water; Solubility: The solubility of Examples 2-4 is basically 0, and the water resistance is excellent; the solubility of Comparative Examples 1-3 is nearly 100%, and it is not water resistant.

[0097] Initial dry adhesion: Since the Tg of the film-forming agent of Examples 2-4 is 10-15°C, there is no abnormality in the initial dry adhesion of Examples 2-4, while the seeds of Comparative Examples 1-3 all have the phenomenon of 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 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.

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 acrylic soft 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 pre-emulsion II include, by weight, 30-40 parts of acrylate monomers containing tertiary carbon structures, 12-16 parts of acrylic soft monomers II, and 1-3 parts of acrylic acid.

4. The acrylic polymer emulsion film-forming agent according to claim 3, characterized in that: The structure of the tertiary carbon structure-containing acrylic acid ester monomer is 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 initiator solution I is an initiator solution with a mass fraction of 3-5%, and the initiator solution II is an initiator solution with a mass fraction of 1-3%.

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

7. A seed coating agent, characterized in that: The preparation raw materials include the acrylic polymer emulsion film-forming agent described in 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 include, by weight percentage: 2-9% acrylic polymer emulsion film former, 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% original drug component, 0.1-4% warning color, and water supplemented to 100%.

9. The seed coating agent according to claim 8, characterized in that: The original drug component is selected from one or more combinations of thiamethoxam, metconazole and azoxystrobin.

10. A method for preparing the seed coating agent according to any one of claims 8 to 9, characterized in that: The following steps are involved: S1: Mix water, wetting agent, dispersant and defoamer evenly, then add suspending agent and cellulose ether in turn and stir for 5-20 minutes; S2 then adds acrylic polymer emulsion film-forming agent, technical component, leveling agent, antifreeze agent and warning color in sequence and mixes evenly to obtain seed coating agent.

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