A block polyether sulfonate anionic surfactant, its preparation and application

Abstract

This invention discloses a block polyether sulfonate anionic surfactant with the general structural formula: MSO3-EO b -PO a -EO c -SO3M, where PO is propoxy, EO is ethoxy, and a, b, and c are the average degree of polymerization of PO or EO, ​​with a ranging from 8 to 75 and b+c ranging from 3 to 250. This invention's block polyether sulfonate anionic surfactant exhibits balanced and excellent performance, unaffected by electrolytes, pH, and temperature; it possesses strong emulsifying ability and high interfacial activity, capable of emulsifying oil droplets into smaller nano-sized droplets at a dosage of 1%-10%; when applied to aqueous suspension systems, it solves the problems of particle aggregation, swelling, and storage instability in aqueous suspension systems, effectively reducing viscosity, increasing solids content, exhibiting low foaming, and good oil-water compatibility.

Description

Technical Field

[0001] This invention relates to an alkoxy polyether surfactant, and more particularly to a block polyether sulfonate anionic surfactant, its preparation method, and its application in aqueous suspension systems. Background Technology

[0002] Surfactants, often referred to as "industrial MSG," have a wide range of applications, including pesticides, pharmaceuticals, electronics, petroleum, coatings, inks, dyes, detergents, and personal care products. They are characterized by their small but indispensable usage. Especially in today's world, with heightened global emphasis on environmental protection and safety, the demand for water-based transformation of non-environmentally friendly and unsafe oil-based or solid products in the chemical, pesticide, and dye industries is increasing to achieve safer and more environmentally friendly goals. Simultaneously, companies have a clearer expectation of improving production efficiency, reducing energy consumption, and lowering production costs, leading to the development of water-based suspension systems towards higher solids content, higher storage and usage stability, and lower viscosity.

[0003] Conventional anionic surfactants are sensitive to acids and alkalis and have poor tolerance to electrolytes, but are not sensitive to temperature. Conventional nonionic surfactants, including block copolymers, are sensitive to temperature but have strong tolerance to both acids, alkalis, and electrolytes. Both types of surfactants have significant advantages and disadvantages; in terms of performance, one cannot have everything. Furthermore, most existing block polyether sulfonates are prepared using alkylphenols, triphenylethylphenol, etc., as starting blocks, which have a significant environmental impact and are difficult to degrade.

[0004] Therefore, developing new surfactants with higher performance is of great significance for environmental protection, safety, efficiency improvement and emission reduction in my country's chemical, pesticide, coating, ink, and dye industries. Summary of the Invention

[0005] The purpose of this invention is to provide a block polyether sulfonate anionic surfactant that overcomes the defects of conventional anionic surfactants and provides a novel surfactant with balanced and excellent performance, resistance to acids, alkalis, and electrolytes. The surfactant can increase the solid content of aqueous suspension systems, reduce viscosity, and solve problems such as particle aggregation, swelling, and storage instability of effective substances in aqueous suspension systems.

[0006] Another object of the present invention is to provide a method for preparing the block polyether sulfonate anionic surfactant.

[0007] Another object of the present invention is to provide an application of the block polyether sulfonate anionic surfactant.

[0008] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: a block polyether sulfonate anionic surfactant, with the general structural formula: MSO3-EOb -PO a -EO c -SO3M, where PO is propoxy and EO is ethoxy, PO and EO are block copolymers in any order, a, b, and c are the average degree of polymerization of PO or EO, ​​a ranges from 8 to 75, and b+c ranges from 3 to 250.

[0009] The block polyether sulfonate anionic surfactant, preferably, has a value of a ranging from 50 to 60 and a value of b+c ranging from 135 to 165 in its general structural formula.

[0010] The block polyether sulfonate anionic surfactant, preferably, has M in its general structural formula as any one of Na, K, NH4, Mg, and Ca.

[0011] The method for preparing the block polyether sulfonate anionic surfactant includes the following steps:

[0012] 1) Using propylene glycol as an initiator, a block alkoxylation reaction is carried out with propylene oxide and ethylene oxide under the action of a catalyst to obtain block polyether;

[0013] 2) The block polyether obtained in step 1) is subjected to sulfonation reaction with aminosulfonic acid as sulfonating agent and urea as catalyst, and after neutralization, the block polyether sulfonate anionic surfactant is obtained.

[0014] More specifically, the steps of the method include:

[0015] A. Add the initiator propylene glycol and alkali metal catalyst to the reactor, purge with nitrogen, raise the temperature, and dehydrate under vacuum conditions;

[0016] B. Introduce metered propylene oxide and carry out the etherification reaction at an internal temperature of 100℃-160℃. The reaction pressure shall not exceed 0.4Mpa. After the material is introduced, keep it at the temperature for aging.

[0017] C. A metered amount of ethylene oxide is introduced, and the etherification reaction is carried out at a temperature of 100℃-160℃ in the reactor. The reaction pressure does not exceed 0.4 MPa. After the material is introduced, the reactor is kept warm and aged. After vacuum degassing, the reactor is cooled to obtain block polyether.

[0018] D. The block polyether obtained above is sulfonated with aminosulfonic acid as an agent and urea as a catalyst, and then sulfonated at 80-150°C. After neutralization, the block polyether sulfonate anionic surfactant is obtained.

[0019] Preferably, the alkali metal catalyst is selected from sodium hydroxide, potassium hydroxide, sodium methoxide or potassium methoxide, and the amount of catalyst used is 1-15% of the weight of the initiator.

[0020] In step A above, the dehydration temperature is 80-130℃, preferably 100-120℃, and the dehydration time is 2-20h, preferably 1-3h.

[0021] In step B above, preferably, the etherification reaction temperature is 110-150℃ and the reaction time is 2-20h.

[0022] In step C above, preferably, the etherification reaction is carried out at 120-150°C for 2-20 hours.

[0023] In the method described, the molar ratio of the initiator to propylene oxide and ethylene oxide is 1:(7-74):(3-250), preferably 1:(49-59):(135-165).

[0024] In step D above, the sulfonation reaction temperature is preferably 100-120℃, and the reaction time is 1-9h, preferably 2-6h.

[0025] In step D above, the molar ratio of block polyether to aminosulfonic acid is 1:2-3, preferably 1:2.05-2.2.

[0026] The present invention also provides an application of the block polyether sulfonate anionic surfactant in an aqueous suspension system.

[0027] Furthermore, the amount of the block polyether sulfonate anionic surfactant used in the aqueous suspension system is 1%-10%.

[0028] The aforementioned aqueous suspension system refers to a uniform and stable dispersion system formed by dispersing water-insoluble or water-poorly soluble effective components (functional components or active components) in water as the continuous phase. The applications described in the above technical solutions are not particularly limited, and include, but are not limited to, aqueous suspension systems in pesticides, inks, coatings, electrolytes, detergents, fertilizers, electronics, and personal care products. For example, applying the surfactant of this invention to pesticide suspensions can increase the solid content of the active ingredient from 5-45% to 30%-70%, while also resulting in lower viscosity, less foam, better self-dispersibility, reduced pesticide costs, and improved efficacy.

[0029] Beneficial effects: The block polyether sulfonate anionic surfactant of the present invention contains functional groups such as EO and PO, which are typical of block polyethers in nonionic surfactants, and contains specific block polyether segments, which can improve the affinity with the active ingredient in the suspension system, prevent it from falling off the surface of the active ingredient particles, and provide steric hindrance; at the same time, it contains anionic sulfonic acid groups, which provide electrostatic repulsion, making the suspension system more stable and unaffected by electrolytes, pH and temperature.

[0030] The block polyether sulfonate anionic surfactant described above has the following advantages in aqueous suspensions:

[0031] 1) It has strong emulsifying ability and high interfacial activity. At a dosage of 1%-10%, it can emulsify oil droplets into smaller nano-sized droplets. It solves the problems of particle aggregation, swelling and storage instability of effective particles with a particle size of ≤5 micrometers or even 100 nanometers in aqueous suspension systems. Since the smaller the particles, the larger the specific surface area, the larger the amount of conventional surfactants required. However, by adding a small amount of the surfactant described in this invention, particle aggregation and swelling can be effectively inhibited, and its storage stability can be greatly improved.

[0032] 2) It has strong resistance to temperature, acid and alkali and electrolytes, and has excellent and balanced performance.

[0033] 3) When applied to aqueous suspension systems, it effectively reduces the viscosity of the system, increases the solids content, exhibits low foaming, good oil-water compatibility, and inhibits particle aggregation and growth. The block polyether sulfonate anionic surfactant addresses the problem of high solids content in aqueous suspension systems, increasing the solids content to 20%-70% and reducing the proportion of water in the system, thereby reducing the unit cost of active ingredients, transportation costs, and carbon emissions. Furthermore, it can reduce system viscosity and improve the pulverization efficiency of aqueous suspension systems, thus reducing unit energy consumption and increasing production capacity. The unique molecular structure of the block polyether sulfonate anionic surfactant also effectively solves the problems of defoaming and incompatibility between the oil and water phases in aqueous suspension systems with high solids content.

[0034] 4) Raw materials are widely available, the preparation process is simple, and the cost is low. The synthetic methods involved are characterized by simple synthesis processes, mild reaction conditions, no ultra-high temperature or high pressure reaction conditions, and high yield.

[0035] 5) The resulting product is easily biodegradable, environmentally friendly, and safe. Detailed Implementation

[0036] The present invention will now be described in detail with reference to specific embodiments. These embodiments are for illustrative purposes only, and the scope of protection of the present invention is not limited to the specific implementation methods, but is defined by the claims.

[0037] Example 1

[0038] One structure is NaSO3-EO b -PO 55 -EO c The preparation method of the block polyether sulfonate anionic surfactant of -SO3Na(b+c=160) is as follows:

[0039] At a reactor temperature of 25℃, 76g of propylene glycol (1mol) and 7g of potassium hydroxide were added to the reactor. After replacing the air with nitrogen twice, the reactor was evacuated to a vacuum of -0.085 MPa. The temperature was raised to 100℃ and kept at 100℃ for 2 hours to remove moisture. The vacuum pump was then turned off, and 3132g (54mol) of propylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 130℃ and the reaction pressure was kept below 0.2 MPa. After the material was introduced, the reactor was kept at a high temperature for 4 hours to age. Then, 7040g (160mol) of ethylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 120℃ and the reaction pressure was kept below 0.2 MPa. After the material was introduced, the reactor was kept at a high temperature for 5 hours to age. After the reaction was completed, the vacuum was turned on, and the reactor was degassed for 0.5 hours before cooling to obtain the intermediate product, block polyether.

[0040] The block polyether obtained above was added to a 20L reactor, along with 204g of aminosulfonic acid and 50g of urea. Stirring was started, and the temperature was raised to 110℃. The reaction was carried out at 105-110℃ for 4 hours. Sodium hydroxide was added for ion exchange to obtain block polyether sulfonate anionic surfactant 1.

[0041] Example 2

[0042] One structure is NaSO3-EO b -PO 50 -EO c The preparation method of the block polyether sulfonate anionic surfactant of -SO3Na(b+c=150) is as follows:

[0043] At a reactor temperature of 25℃, 76g (1mol) propylene glycol and 11g KOH were added to the reactor. After replacing the air with nitrogen twice, the reactor was evacuated to a vacuum of -0.085MPa. The temperature was raised to 100℃ and held at 100℃ for 2 hours to remove moisture. The vacuum pump was then turned off, and 2842g (49mol) propylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 130℃ and the reaction pressure was kept below 0.2MPa. After the material was introduced, the reactor was kept at a high temperature for 3 hours to age. Then, 6600g (150mol) ethylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 120℃ and the reaction pressure was kept below 0.2MPa. After the material was introduced, the reactor was kept at a high temperature for 4 hours to age. After the reaction was completed, the vacuum was turned on, and the reactor was degassed for 0.5 hours before cooling to obtain the intermediate product, block polyether.

[0044] The block polyether obtained above was added to a 20L reactor, along with 236g of aminosulfonic acid and 60g of urea. Stirring was started, and the temperature was raised to 110℃. The reaction was carried out at 105-110℃ for 5 hours. Sodium hydroxide was added for ion exchange to obtain block polyether sulfonate anionic surfactant 2.

[0045] Example 3

[0046] One structure is NaSO3-EO b -PO 60 -EO c The preparation method of the block polyether sulfonate anionic surfactant of -SO3Na(b+c=150) is as follows:

[0047] At a reactor temperature of 25°C, 76g (1mol) of propylene glycol and 10g of potassium methoxide were added to the reactor. After replacing the air with nitrogen twice, the reactor was evacuated to a vacuum of -0.085 MPa. The temperature was raised to 100°C and held at 100°C for 2 hours to remove moisture. The vacuum pump was then turned off, and 3422g (59mol) of propylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 130°C and the reaction pressure was kept below 0.2 MPa. After the material was introduced, the reactor was kept at a high temperature for 6 hours to age. Then, 6600g (150mol) of ethylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 120°C and the reaction pressure was kept below 0.2 MPa. After the material was introduced, the reactor was kept at a high temperature for 6 hours to age. After the reaction was completed, the vacuum was turned on, and the reactor was degassed for 0.5 hours before cooling to obtain the intermediate product, block polyether.

[0048] The block polyether obtained above was added to a 20L reactor, along with 212g of aminosulfonic acid and 60g of urea. Stirring was started, and the temperature was raised to 110℃. The reaction was carried out at 105-110℃ for 5 hours. Sodium hydroxide was added for ion exchange to obtain block polyether sulfonate anionic surfactant 3.

[0049] Example 4

[0050] One structure is NaSO3-EO b -PO 60 -EO c The preparation method of the block polyether sulfonate anionic surfactant of -SO3Na(b+c=135) is as follows:

[0051] At a reactor temperature of 25℃, 76g (1mol) propylene glycol and 9g potassium methoxide were added to the reactor. After replacing the air with nitrogen twice, the reactor was evacuated to a vacuum of -0.085 MPa. The temperature was raised to 100℃ and kept at 100℃ for 2 hours to remove moisture. The vacuum pump was then turned off, and 3422g (59mol) propylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 130℃ and the reaction pressure was kept below 0.2 MPa. After the material was introduced, the reactor was kept at a high temperature for 6 hours to age. Then, 5940g (135mol) ethylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 120℃ and the reaction pressure was kept below 0.2 MPa. After the material was introduced, the reactor was kept at a high temperature for 6 hours to age. After the reaction was completed, the vacuum was turned on, and the reactor was degassed for 0.5 hours before cooling to obtain the intermediate product, block polyether.

[0052] The block polyether obtained above was added to a 20L reactor, along with 228g of aminosulfonic acid and 50g of urea. Stirring was started, and the temperature was raised to 110℃. The reaction was carried out at 105-110℃ for 5 hours. Sodium hydroxide was added for ion exchange to obtain block polyether sulfonate anionic surfactant 4.

[0053] Example 5

[0054] One structure is NaSO3-EO b -PO8-EO c The preparation method of the block polyether sulfonate anionic surfactant of -SO3Na(b+c=10) is as follows:

[0055] At a reactor temperature of 25°C, 76g of propylene glycol (1mol) and 7g of sodium hydroxide were added to the reactor. After replacing the air with nitrogen twice, the reactor was evacuated to a vacuum of -0.085 MPa. The temperature was raised to 100°C and held at 100°C for 2 hours to remove moisture. The vacuum pump was then turned off, and 406g (7mol) of propylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 130°C and the reaction pressure was kept below 0.2 MPa. After the material was introduced, the reactor was kept at a high temperature for 2 hours to age. Then, 440g (10mol) of ethylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 120°C and the reaction pressure was kept below 0.2 MPa. After the material was introduced, the reactor was kept at a high temperature for 2 hours to age. After the reaction was completed, the vacuum was turned on, and the reactor was degassed for 0.5 hours before cooling to obtain the intermediate product, block polyether.

[0056] The block polyether obtained above was added to a 5L reactor, along with 204g of aminosulfonic acid and 50g of urea. Stirring was started, and the temperature was raised to 110℃. The reaction was carried out at 105-110℃ for 4 hours. Sodium hydroxide was added for ion exchange to obtain block polyether sulfonate anionic surfactant 5.

[0057] Example 6

[0058] One structure is NaSO3-EO b -PO 18 -EO c The preparation method of the block polyether sulfonate anionic surfactant of -SO3Na(b+c=250) is as follows:

[0059] At a reactor temperature of 25℃, 76g (1mol) propylene glycol and 11g KOH were added to the reactor. After replacing the air with nitrogen twice, the reactor was evacuated to a vacuum of -0.085MPa. The temperature was raised to 100℃ and held at 100℃ for 2 hours to remove moisture. The vacuum pump was then turned off, and 986g (17mol) propylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 130℃ and the reaction pressure was kept below 0.2MPa. After the material was introduced, the reactor was kept at a high temperature for 3 hours to age. Then, 11000g (250mol) ethylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 120℃ and the reaction pressure was kept below 0.2MPa. After the material was introduced, the reactor was kept at a high temperature for 5 hours to age. After the reaction was completed, the vacuum was turned on, and the reactor was degassed for 0.5 hours before cooling to obtain the intermediate product, block polyether.

[0060] The block polyether obtained above was added to a 20L reactor, along with 236g of aminosulfonic acid and 60g of urea. Stirring was started, and the temperature was raised to 110℃. The reaction was carried out at 105-110℃ for 4 hours. Sodium hydroxide was added for ion exchange to obtain block polyether sulfonate anionic surfactant 6.

[0061] Example 7

[0062] One structure is NaSO3-EO b -PO 75 -EO c The preparation method of the block polyether sulfonate anionic surfactant of -SO3Na(b+c=50) is as follows:

[0063] At a reactor temperature of 25℃, 76g (1mol) propylene glycol and 10g potassium methoxide were added to the reactor. After replacing the air with nitrogen twice, the reactor was evacuated to a vacuum of -0.085MPa. The temperature was raised to 100℃ and kept at 100℃ for 2 hours to remove moisture. The vacuum pump was then turned off, and 4292g (74mol) propylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 130℃ and the reaction pressure was kept below 0.2MPa. After the material was introduced, the reactor was kept at a high temperature for 6 hours to age. Then, 2200g (50mol) ethylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 120℃ and the reaction pressure was kept below 0.2MPa. After the material was introduced, the reactor was kept at a high temperature for 3 hours to age. After the reaction was completed, the vacuum was turned on, and the reactor was degassed for 0.5 hours before cooling to obtain the intermediate product, block polyether.

[0064] The block polyether obtained above was added to a 10L reactor, along with 212g of aminosulfonic acid and 60g of urea. Stirring was started, and the temperature was raised to 110℃. The reaction was carried out at 105-110℃ for 4 hours. Sodium hydroxide was added for ion exchange to obtain block polyether sulfonate anionic surfactant 7.

[0065] Example 8

[0066] One structure is NaSO3-EO b -PO 75 -EO c The preparation method of the block polyether sulfonate anionic surfactant of -SO3Na(b+c=100) is as follows:

[0067] At a reactor temperature of 25℃, 76g (1mol) propylene glycol and 9g potassium methoxide were added to the reactor. After replacing the air with nitrogen twice, the reactor was evacuated to a vacuum of -0.085 MPa. The temperature was raised to 100℃ and held at 100℃ for 2 hours to remove moisture. The vacuum pump was then turned off, and 4292g (74mol) propylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 130℃ and the reaction pressure was kept below 0.2 MPa. After the material was introduced, the reactor was kept at a high temperature for 2 hours to age. Then, 4400g (100mol) ethylene oxide was introduced. During the reaction, the temperature of the material inside the reactor was kept at 120℃ and the reaction pressure was kept below 0.2 MPa. After the material was introduced, the reactor was kept at a high temperature for 2 hours to age. After the reaction was completed, the vacuum was turned on, and the reactor was degassed for 0.5 hours before cooling to obtain the intermediate product, block polyether.

[0068] The block polyether obtained above was added to a 20L reactor, along with 228g of aminosulfonic acid and 50g of urea. Stirring was started, and the temperature was raised to 110℃. The reaction was carried out at 105-110℃ for 4 hours. Sodium hydroxide was added for ion exchange to obtain block polyether sulfonate anionic surfactant 8.

[0069] Evaluation of surfactant emulsifying ability

[0070] Take an appropriate amount of solvent oil No. 150, add 8% wt of the block polyether sulfonate anionic surfactant prepared in Examples 1-8, stir for 30 minutes, and dilute the resulting sample 200 times in 250 ml of standard hard water with a stopper. After emulsification, test the particle size. The smaller the particle size, the stronger the emulsification ability. The results are shown in Table 1.

[0071] Comparative Example 1

[0072] The emulsifying ability of the block polyether sulfonate anion of the present invention was evaluated using a commercially available nonionic block polyether (the indicated structural formula is as follows) surfactant instead of the block polyether sulfonate anion of the present invention, and the results are shown in Table 1.

[0073]

[0074] Comparative Example 2

[0075] Commercially available conventional anionic emulsifiers (C 12 H 25 The C6H4SO3)2Ca surfactant was used to replace the block polyether sulfonate anion of the present invention, and its emulsifying ability was evaluated using the same method. The results are shown in Table 1.

[0076] Comparative Example 3

[0077] The conventional surfactants of Comparative Example 1 and Comparative Example 2 were mixed at a mass ratio of 1:2 to replace the block polyether sulfonate anion of the present invention, and their emulsifying ability was evaluated in the same manner. The results are shown in Table 1.

[0078] Table 1 Emulsification performance of Examples 1-8

[0079] Example Droplet size (D90) after 200-fold dilution Example 1 35 nanometers Example 2 62 nanometers Example 3 48 nanometers Example 4 51 nanometers Example 5 89 nanometers Example 6 94 nanometers Example 7 75 nanometers Example 8 74 nanometers Comparative Example 1 Cannot emulsify Comparative Example 2 2153 nanometers Comparative Example 3 1652 nanometers

[0080] As shown in Table 1, under the same conditions, the surfactant prepared by this invention exhibits excellent emulsifying properties. A single emulsifier can emulsify solvent oil No. 150 to the nanoscale, demonstrating superior emulsifying performance. In contrast, traditional emulsifiers require multiple applications, and their emulsifying capabilities only meet routine requirements.

[0081] Example 9

[0082] A water-based disperse dye ink, with the following specific formulation (wt%):

[0083] Disperse Red: 20%

[0084] Thiodiethylene glycol: 15%

[0085] Diethylene glycol: 8%

[0086] Propylene glycol: 3%

[0087] Sodium benzoate: 0.3%

[0088] Surfactant in Example 1: 2%

[0089] Sodium salt of alkyl naphthalene sulfonate formaldehyde condensate: 2%

[0090] AEO3:5%

[0091] Deionized water: Replenish to 100%

[0092] The disperse dye ink of this embodiment has high sand milling efficiency, and the dye can be sand milled to D90:72 nanometers in 5 hours. After a 14-day aging and storage test at 54°C, the suspension system showed no stratification or crusting, good fluidity, a system viscosity of 1.8 CPS, and a particle size of approximately 80 nanometers, with virtually no change in particle size.

[0093] Example 10

[0094] A water-based colorant, with the following specific formula (wt%):

[0095] Permanent Red: 30%

[0096] Sodium maleic acid-acrylic acid copolymer: 2%

[0097] Surfactant in Example 2: 3%

[0098] Xanthan gum: 0.1%

[0099] Sodium benzoate: 0.5%

[0100] Defoamer: 0.1%

[0101] Deionized water: Replenish to 100%

[0102] This embodiment of the water-based color paste exhibits high grinding efficiency, capable of grinding permanent red particles to D90:80 nanometers in just 40 minutes, far exceeding the requirements for color paste applications. This results in more vibrant colors and higher refractive indices. After a 14-day aging and storage test at 54°C, the suspension system showed slight stratification without clumping, good fluidity, a system viscosity of 100 cps, and no change in particle size, significantly improving the application performance of the color paste.

[0103] Example 11

[0104] A high-content pesticide aqueous suspension, with the following specific formula (wt%):

[0105] Diuron: 64%

[0106] Sodium salt of maleic acrylate copolymer: 4%

[0107] Surfactant in Example 3: 2%

[0108] Xanthan gum: 0.1%

[0109] Sodium benzoate: 0.5%

[0110] Glycerol: 3%

[0111] Defoamer: 0.2%

[0112] Deionized water: Replenish to 100%

[0113] This embodiment of the aqueous suspension exhibits high sand milling efficiency, capable of milling diuron particles to a D90 of 70 nanometers in just 40 minutes. This efficiency far surpasses that of conventional surfactants, resulting in smaller pesticide particles that are more easily absorbed by crops during field application. After a 14-day aging storage test at 54°C, the suspension system showed slight stratification without clumping, good fluidity, a viscosity of 400 cps, and no change in particle size, significantly improving the pesticide's application performance.

[0114] Aqueous suspension systems, especially those with high solids content, are prone to generating excessive foam during pulverization. Conventional defoamers are often ineffective at eliminating this foam, leading to low pulverization efficiency, increased system viscosity, elevated temperature, and even solidification within the pulverizing equipment, resulting in production accidents. In this embodiment, the addition of the block polyether sulfonate anionic surfactant, combined with a small amount of conventional defoamer, or even without adding any defoamer, effectively solves the defoaming problem during pesticide preparation.

[0115] Example 12

[0116] A nano-aqueous suspension system – a nano-pesticide – has the following specific formulation:

[0117] Emamectin benzoate: 28%

[0118] Sodium maleic acid-acrylic acid copolymer: 6%

[0119] Surfactant in Example 4: 3%

[0120] White oil: 3%

[0121] Glycerol: 3%

[0122] Attapulgite: 1.5%

[0123] Sodium benzoate: 0.2%

[0124] Defoamer: 0.1%

[0125] Deionized water: Replenish to 100%

[0126] This embodiment demonstrates high grinding efficiency, reducing the particle size of emamectin benzoate to D90:92 nanometers in just 6 hours, far exceeding the grinding efficiency of conventional surfactants. This results in smaller pesticide particles, making them easier for crops to absorb during field application. After a 14-day aging storage test at 54℃, the suspension system showed no stratification or agglomeration, exhibiting good fluidity with a viscosity of 100 cps and no change in particle size, significantly improving the pesticide's application performance.

[0127] As can be seen from Examples 9-12, the surfactant of the present invention can be widely used in aqueous suspension systems, and has the advantages of high milling efficiency, low viscosity of suspension system, low foaming, effective suppression of particle size expansion in suspension system, improved storage stability, and improved product shelf life and end-use performance.

[0128] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A block polyether sulfonate anionic surfactant characterized in that, The general structure of the anionic surfactant is: MSO3-EO b -PO a -EO c -SO3M, wherein PO is propoxy, EO is ethoxy, PO and EO are block copolymerized in any order, a, b, c are average polymerization degrees of PO or EO, a ranges from 50 to 60, and b + c ranges from 135 to 165.

2. The block polyether sulfonate anionic surfactant according to claim 1, characterized in that, Said M is Na, K, NH4, Mg or Ca.

3. A method for preparing the block polyether sulfonate anionic surfactant of claim 1, comprising the following steps: 1) block alkoxylation of propylene glycol as a starter with propylene oxide and ethylene oxide in the presence of a catalyst to obtain a block polyether; 2) sulfonation of the block polyether obtained in step 1) with sulfamic acid as a sulfonating agent and urea as a catalyst, and neutralization to obtain the block polyether sulfonate anionic surfactant.

4. The production method according to claim 3, characterized by, The method comprises the following steps: A. Put the starter propylene glycol and an alkali metal catalyst into a reaction kettle, replace with nitrogen, heat, and dehydrate under vacuum; B. Introduce a metered amount of propylene oxide, and perform etherification at a kettle temperature of 100-160℃ and a reaction pressure of no more than 0.4 Mpa, and then keep aging after the introduction is completed; C. Introduce a metered amount of ethylene oxide, and perform etherification at a kettle temperature of 100-160℃ and a reaction pressure of no more than 0.4 Mpa, and then keep aging after the introduction is completed, and then reduce the temperature after vacuum degassing to obtain a block polyether; D. Add the sulfonating agent sulfamic acid and the catalyst urea to the block polyether obtained above, and perform sulfonation at 80-150℃, and then neutralize to obtain the block polyether sulfonate anionic surfactant.

5. The preparation method according to claim 4, characterized in that, The alkali metal catalyst is selected from sodium hydroxide, potassium hydroxide, sodium methoxide or potassium methoxide, and the catalyst is used in an amount of 1-15% by weight of the starter.

6. The preparation method according to claim 4, characterized in that, In the above step B, the etherification temperature is 110-150℃, and the reaction time is 2-20 h; In the above step C, the etherification temperature is 120-150℃, and the reaction time is 2-20 h; In the above step D, the sulfonation temperature is 100-120℃, and the reaction time is 1-9 h; The molar ratio of the starter to propylene oxide and ethylene oxide is 1: (49-59) : (135-165), and the molar ratio of the block polyether to sulfamic acid is 1:2-3.

7. Use of the block polyether sulfonate anionic surfactant of claim 1 in an aqueous suspension system.

8. Use according to claim 7, characterized in that, The amount of the block polyether sulfonate anionic surfactant used in the aqueous suspension system is 1-10%.

9. Use according to claim 7, characterized in that, The block polyether sulfonate anionic surfactant is used in a pesticide suspension concentrate.

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