A high-active-content agricultural suspension concentrate dispersant and its preparation method

Abstract

The present invention relates to the technical field of suspension concentrate dispersants, particularly to IPC A01N25, and more specifically to a high-active-content agricultural suspension concentrate dispersant and a preparation method thereof. The preparation raw materials of the present invention include polyethylene glycol monomethyl ether monomer, methacrylic acid monomer, acrylic ester monomer, alcohol, toluene, a catalyst, an initiator, and phenothiazine. The high-active-content agricultural suspension concentrate dispersant is synthesized through esterification and polymerization of some of the raw materials. The dispersant exhibits high adsorption fastness, high adsorption thickness, increased interparticle lubricity, and anti-foaming and wetting properties.

Description

Technical Field

[0001] The present invention relates to the technical field of suspension concentrate dispersants, in particular to IPC A01N25, and more specifically to an agricultural suspension concentrate dispersant with high active content and a preparation method thereof. Background Art

[0002] Suspension concentrates use water as a medium and, with the aid of additives, grind and pulverize the insoluble or slightly soluble solid drug into a uniform dispersion in water. These additives are typically dispersants, which inhibit flocculation and aggregation of particles in the dispersed phase, stabilizing the suspension formulation and promoting dilution of the dispersion into a uniform suspension upon addition to water.

[0003] Currently commonly used dispersants include: lignin sulfonate, naphthalene sulfonate, alkyl naphthalene sulfonate formaldehyde condensate, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, etc. The existing patent CN201410326621.9 discloses a carboxylated alkali lignin sulfonate dye dispersant and its preparation method. The formula of the reaction raw materials is: 100 parts of alkali lignin, 20-60 parts of sulfonating agent, 2-20 parts of aldehyde compound, and 20-45 parts of carboxylic acid compound, calculated by mass fraction. It has good dispersing properties, but has reducing properties to some azo compounds.

[0004] Dispersion issues are common in suspension concentrate applications. For example, some dispersants are difficult to deform, have weak adsorption, and easily fall off the particle surface, resulting in increased viscosity and even excessive foaming during grinding. Therefore, there is a need to develop a high-active-content dispersant for agricultural suspension concentrates that improves adsorption fastness, enhances adsorption layer thickness, increases interparticle lubrication, and possesses certain foam suppression and wetting properties, as well as a method for its preparation. Summary of the Invention

[0005] In order to solve the problems in the prior art, the first aspect of the present invention provides a high-active content agricultural suspension concentrate dispersant, the raw materials for its preparation include polyethylene glycol monomethyl ether monomer, methacrylic acid monomer, acrylate monomer, alcohol, toluene, catalyst, initiator, and phenothiazine.

[0006] Preferably, the high-active content agricultural suspension concentrate dispersant, calculated by weight, comprises raw materials comprising 180-200 parts of polyethylene glycol monomethyl ether monomer, 20-90 parts of methacrylic acid monomer, 50-120 parts of acrylate monomer, 2-4 parts of alcohol, 20-40 parts of toluene, 2-10 parts of catalyst, 0.01-10 parts of initiator, and 1-10 parts of phenothiazine.

[0007] Preferably, the polyethylene glycol monomethyl ether monomer includes one or more of MPEG (polyethylene glycol monomethyl ether)-500, MPEG-700, MPEG-1200, and MPEG-2000; more preferably, it is MPEG-700.

[0008] Preferably, the hydroxyl value of the MPEG-700 is 60 to 150 mgKOH / g.

[0009] Preferably, the MPEG-700 is purchased from Haian Petrochemical Plant in Jiangsu Province, and the model is MPEG.

[0010] Preferably, the acrylic acid ester monomer includes one or more of methyl acrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, and ethyl methacrylate.

[0011] Preferably, the alcohol is one or both of propylene glycol and isopropyl alcohol.

[0012] Preferably, the catalyst is methanesulfonic acid.

[0013] Preferably, the CAS number of the methanesulfonic acid is 75-75-2.

[0014] Preferably, the initiator is one or more of dibenzoyl peroxide BPO, tert-butyl perbenzoate TBPB, ethyl 3-ethoxypropionate EEP, and tert-butyl peroxy-2-ethylhexanoate TBPO.

[0015] A second aspect of the present invention provides a method for preparing a high-active content agricultural suspension concentrate dispersant, comprising the following steps:

[0016] Step 1: Esterification reaction:

[0017] S1: adding polyethylene glycol monomethyl ether monomer and phenothiazine into an esterification kettle;

[0018] S2: Heat the esterification kettle until the temperature reaches 60-80°C, then add methacrylic acid monomer and catalyst into the esterification kettle;

[0019] S3: Turn on the cooling water, cool the esterification kettle to room temperature, and add toluene into the esterification kettle;

[0020] S4: heating the esterification kettle to 120-140°C, reacting for 2 hours, then heating the esterification kettle to 150-152°C, reacting for 5-7 hours;

[0021] S5: taking a sample, determining the acid value, cooling to 35-45° C., and preparing a polymer;

[0022] Step 2: Polymerization reaction:

[0023] M1: Add methacrylic acid monomer and acrylic acid ester monomer to the esterification kettle containing the polymer obtained after the esterification reaction, mix and set aside;

[0024] M2: Add alcohol to the polymerization reactor, then add toluene and stir thoroughly; heat the polymerization reactor to 110-130°C;

[0025] M3: Add the mixture and initiator in the esterification reactor in step M1 dropwise into the polymerization reactor at the same time. After the addition is complete, react for 2.5 to 3.5 hours at a reaction temperature of 113 to 117°C.

[0026] M4: Toluene in the polymerization reactor is vacuum stripped, and the residual monomer is purified by steam stripping, then neutralized with alkali and filtered to obtain an agricultural suspension concentrate dispersant.

[0027] Preferably, the acid value in step S5 is 15 to 25 mgKOH / g; more preferably, it is 17 to 20 mgKOH / g.

[0028] Preferably, the base used for neutralization is one or more of sodium hydroxide, potassium hydroxide, ammonia water, and ethanolamine.

[0029] In the present invention, a specific amount of MPEG-700, phenothiazine, methacrylic acid, and a specific catalyst, methanesulfonic acid, are selected and heated to 150-152°C to improve the efficiency of the esterification reaction while producing a specific polymer. The inventors unexpectedly discovered that by selecting a specific amount of MPEG-700, phenothiazine, methacrylic acid, and a specific catalyst, methanesulfonic acid, and heating the reaction to 150-152°C, the methacrylic acid and MPEG-700 react to the maximum extent possible, improving the efficiency of the esterification reaction while producing a specific polymer. Methanesulfonic acid is selected as the catalyst because it has high catalytic activity, is non-corrosive to equipment, simplifies the process, is environmentally friendly, and is easily separated from the product. During the reaction, if the temperature is too low, the esterification reaction will be incomplete, wasting some raw materials and increasing costs. If the temperature is too high, some methacrylic acid will polymerize, preventing the desired polymer from being produced, thus affecting the next reaction and, in turn, the performance of the dispersant.

[0030] In the present invention, the polymer obtained in the esterification reaction, methyl methacrylate, and methacrylic acid are added dropwise, along with an initiator. The reaction temperature is controlled at 113-117°C, followed by vacuum stripping, purification, steam stripping, neutralization, and filtration to obtain a uniform polymer, i.e., a dispersant with high adsorption fastness, a high adsorption layer thickness, and a high active content. The inventors speculate that the dropwise addition of the mixture and initiator can cause the polymer, methyl methacrylate, and methacrylic acid to copolymerize. The resulting copolymer structure has good deformability and can be firmly adsorbed on the particle surface, preventing excessive foaming without changing the viscosity of the entire system. Simultaneously, controlling the reaction temperature to a stable level of 113-117°C can prevent the polymer from flocculating.

[0031] Beneficial effects

[0032] In the present invention, a certain amount of MPEG-700, phenothiazine, methacrylic acid and a specific catalyst, methanesulfonic acid, are selected and heated to 150-152° C., thereby improving the efficiency of the esterification reaction and obtaining a specific polymer.

[0033] In the present invention, the polymer obtained in the esterification reaction, methyl methacrylate and methacrylic acid are added dropwise, and an initiator is added dropwise at the same time, and the reaction temperature is controlled to be 113-117° C., followed by vacuum stripping, purification, steam stripping, neutralization and filtration to obtain a uniform polymer, i.e., a dispersant with high adsorption fastness, high adsorption layer thickness and high active content. DETAILED DESCRIPTION

[0034] Example 1

[0035] By weight, 186 parts of MPEG (polyethylene glycol monomethyl ether)-700 and 4 parts of phenothiazine were added to an esterification reactor and heated while stirring. When the temperature of the reactor rose to 65°C, 26 parts of methacrylic acid and 4 parts of methanesulfonic acid were added dropwise. The reactor was cooled with cold water, and 29 parts of toluene was added dropwise. The reaction was heated at 130°C for 8 hours. The temperature was maintained at 130°C during the reaction. It was found that the esterification reaction was incomplete.

[0036] Example 2

[0037] By weight, 186 parts of MPEG (polyethylene glycol monomethyl ether)-700 and 4 parts of phenothiazine were added to a reactor and heated while stirring. When the temperature of the reactor rose to 65°C, 26 parts of methacrylic acid and 4 parts of methanesulfonic acid were added dropwise. The reactor was cooled with cold water, and 29 parts of toluene was added dropwise and heated to 130°C. After reacting for 2 hours, the temperature was heated to 150°C and reacted for 6 hours. The esterification reaction was found to be complete.

[0038] Example 3

[0039] 186 parts of MPEG (polyethylene glycol monomethyl ether)-700 and 4 parts of phenothiazine were added to a reactor by weight and heated while stirring. When the temperature of the reactor reached 65°C, 26 parts of methacrylic acid and 4 parts of methanesulfonic acid were added dropwise. The reactor was cooled with cold water, and 29 parts of toluene was added dropwise. The temperature was heated to 130°C. After reacting for 2 hours, the temperature was increased to 160°C and the reaction was continued for 6 hours. It was detected that some methacrylic acid was polymerized.

[0040] Example 4

[0041] The entire polymer obtained by the esterification reaction in Example 2, 117 parts of methyl methacrylate, and 6 parts of methacrylic acid were mixed in an esterification kettle to form a mixture, calculated by weight, and set aside. Two parts of propylene glycol were added to the polymerization kettle, followed by 3 parts of toluene, and stirred thoroughly. The polymerization kettle was heated to 117°C. The mixture in the esterification kettle was added dropwise to the polymerization kettle, and 0.1 part of the initiator, t-butyl peroxybenzoate, was simultaneously added dropwise. The addition temperature was controlled at 117°C. The mixture was added dropwise over 3 hours, and the initiator was added dropwise over 3 hours and 9 minutes. After the additions were complete, the temperature was controlled at 125°C for 3 hours. Flocculation was observed during the polymerization process. Ammonia was used as the base for neutralization.

[0042] Example 5

[0043] The entire polymer obtained by the esterification reaction in Example 2, 117 parts of methyl methacrylate, and 6 parts of methacrylic acid were mixed in an esterification kettle by weight to form a mixture for later use. Two parts of propylene glycol were added to the polymerization kettle, followed by 3 parts of toluene, and the mixture was stirred thoroughly. The polymerization kettle was heated to 117°C. The mixture in the esterification kettle was added dropwise to the polymerization kettle, and 0.1 part of the initiator, t-butyl peroxybenzoate, was simultaneously added dropwise. The addition temperature was controlled at 117°C. The mixture was added dropwise over 3 hours, and the initiator was added dropwise over 3 hours and 9 minutes. After the additions were complete, the temperature was controlled at 115°C and the mixture was reacted for 3 hours. The mixture was then vacuum stripped, purified, stripped, neutralized, and filtered. A uniform polymer was obtained. The base used for neutralization was sodium hydroxide.

[0044] Example 6

[0045] The entire polymer obtained by the esterification reaction in Example 2, 62 parts of methyl methacrylate, and 60 parts of methacrylic acid were mixed in an esterification kettle by weight to form a mixture for later use. Two parts of propylene glycol were added to the polymerization kettle, followed by 3 parts of toluene, and the mixture was stirred thoroughly. The polymerization kettle was heated to 117°C. The mixture in the esterification kettle was added dropwise to the polymerization kettle, and 0.1 part of the initiator, t-butyl peroxybenzoate, was simultaneously added dropwise. The addition temperature was controlled at 117°C. The mixture was added dropwise over 3 hours, and the initiator was added dropwise over 3 hours and 9 minutes. After the additions were complete, the temperature was controlled at 115°C and the mixture was reacted for 3 hours. The mixture was then vacuum stripped, purified, stripped, neutralized, and filtered. A uniform polymer was obtained. The base used for neutralization was potassium hydroxide.

[0046] Performance Testing

[0047] 1. Weigh 5g of each polymer prepared in Examples 4-6 and prepare a 500mL aqueous solution for later use. Prepare reagents: 0.1% sodium oleate solution and 0.1% anhydrous calcium chloride solution. Take 30mL of the 0.1% sodium oleate solution and dropwise add the prepared polymer solutions of Examples 4-6 to the solution. Observe for precipitation. If precipitation forms, increase the amount of the prepared polymer solution added accordingly. If no precipitation forms, reduce the amount of the prepared polymer solution added accordingly. Determine the critical point V value. A smaller V value indicates better dispersibility. Average the values ​​of the dispersibility V values ​​of Examples 4-6 by repeating the experiment three times. Record the results in Table 1.

[0048] 2. Emulsion stability evaluation: 5% of the polymer (dispersant) prepared in Examples 4 to 6, 45% of fatty acid methyl ester, and 50% of water were mixed in proportion. The emulsion stability test was carried out in accordance with GB / T1603-2001 Pesticide Emulsion Stability. It can be seen that no stratification occurs under high-speed centrifugation conditions, indicating good stability. The dispersant was placed in a bottle, sealed, and placed in a 54°C constant temperature box for 24 hours. The changes were observed and the particle size changes were tested using a laser particle size analyzer. The dispersant of the present invention showed little change before and after heat storage, demonstrating good heat resistance and storage properties. The results are shown in Table 1.

[0049] Table 1

[0050] Example 4 Example 5 Example 6 Flocculation phenomenon have none none Dispersibility V value 2.6 1.4 1.9 54℃, 24 hours storage experiment Unqualified, turbidity and sedimentation Qualified, no turbidity and precipitation Qualified, no turbidity and precipitation <![CDATA[Thermal stability D 50 Particle size μm]]> 4.2 1.45 2.1

Claims

1. A method for preparing a high-active content agricultural suspension concentrate dispersant, characterized in that: The following steps are involved: Step 1: Esterification reaction: S1: adding polyethylene glycol monomethyl ether monomer and phenothiazine into an esterification kettle; S2: Heat the esterification kettle until the temperature reaches 60-80°C, then add methacrylic acid monomer and catalyst into the esterification kettle; S3: Turn on the cooling water, cool the esterification kettle to room temperature, and add toluene into the esterification kettle; S4: heating the esterification kettle to 120-140°C, reacting for 2 hours, then heating the esterification kettle to 150-152°C, reacting for 5-7 hours; S5: taking a sample, determining the acid value, cooling to 35-45° C., and preparing a polymer; Step 2: Polymerization reaction: M1: Add methacrylic acid monomer and acrylic acid ester monomer to the esterification kettle containing the polymer obtained after the esterification reaction, mix and set aside; M2: Add alcohol to the polymerization reactor, then add toluene and stir thoroughly; heat the polymerization reactor to 110-130°C; M3: Add the mixture and initiator in the esterification reactor in step M1 dropwise into the polymerization reactor simultaneously, controlling the temperature of the addition. After the addition is complete, react for 2.5 to 3.5 hours at a reaction temperature of 113 to 117°C. M4: Toluene in the polymerization reactor is vacuum stripped, and the residual monomer is purified by steam stripping, then neutralized with alkali and filtered to obtain an agricultural suspension concentrate dispersant; The high-activity agricultural suspension concentrate dispersant comprises, by weight, 180 to 200 parts of polyethylene glycol monomethyl ether monomer, 20 to 90 parts of methacrylic acid monomer, 50 to 120 parts of acrylic acid ester monomer, 2 to 4 parts of alcohol, 20 to 40 parts of toluene, 2 to 10 parts of catalyst, 0.01 to 10 parts of initiator, and 1 to 10 parts of phenothiazine.

2. The method for preparing a high-active content agricultural suspension concentrate dispersant according to claim 1, characterized in that: The polyethylene glycol monomethyl ether monomer includes one or more of MPEG-500, MPEG-700, MPEG-1200, and MPEG-2000.

3. The method for preparing a high-active content agricultural suspension concentrate dispersant according to claim 1, characterized in that: The acrylic acid ester monomer includes one or more of methyl acrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, and ethyl methacrylate.

4. The method for preparing a high-active content agricultural suspension concentrate dispersant according to claim 1, characterized in that: The alcohol is one or both of propylene glycol and isopropyl alcohol.

5. The method for preparing a high-active content agricultural suspension concentrate dispersant according to claim 1, characterized in that: The catalyst is methanesulfonic acid.

6. The method for preparing a high-active content agricultural suspension concentrate dispersant according to claim 1, characterized in that: The initiator is one or more of dibenzoyl peroxide (BPO), tert-butyl perbenzoate (TBPB), ethyl 3-ethoxypropionate (EEP), and tert-butyl peroxy-2-ethylhexanoate (TBPO).

7. The method for preparing a high-active content agricultural suspension concentrate dispersant according to claim 1, characterized in that: The acid value in the step S5 is 15 to 25 mgKOH / g.

8. The method for preparing a high-active content agricultural suspension concentrate dispersant according to claim 1, characterized in that: The alkali used for the neutralization is one or more of sodium hydroxide, potassium hydroxide, ammonia water, and ethanolamine.