Chlorantraniliprole and lufenuron suspending agent stable at low temperature and preparation method thereof

Abstract

The invention relates to the field of pesticide preparation processing, and discloses a low-temperature stable chlorantraniliprole and lufenuron suspending agent and a preparation method thereof.The core of the suspending agent is that a grafted copolymer with a polypropylene glycol (PPG) temperature-sensitive chain segment serves as a low-temperature self-adaptive stabilizer and cooperates with modified lignosulfonate; during preparation, through a step-by-step process of firstly adding the modified lignosulfonate and then adding the core stabilizer, a stable adsorption layer with internal charge-external steric hindrance is constructed on the surfaces of the particles; the key point of the invention lies in that a compact physical barrier formed by shrinkage of PPG chain segments at low temperature is utilized to effectively inhibit the Oswald ripening of particles and the physical damage of ice crystals. The problems of serious crystallization, agglomeration and poor fluidity at low temperature in the prior art are solved, and the preparation is endowed with excellent low-temperature storage, freeze-thaw stability and dumping performance.

Description

Technical Field

[0001] This invention relates to the field of pesticide formulation processing technology, and in particular to a low-temperature stable chlorantraniliprole and lufenuron suspension and its preparation method. Background Technology

[0002] Chlorantraniliprole and lufenuron are two excellent insecticides with different mechanisms of action and complementary insecticidal spectra. Their combination into water-dispersible suspensions (SCs) is a common technique in agricultural production, which can broaden the control range and delay the development of resistance. However, preparing stable suspensions from two or more solid active ingredients is challenging, especially for the chlorantraniliprole / lufenuron combination system, where its physical stability at low temperatures is particularly problematic.

[0003] During storage, transportation, or use in cold regions, existing technologies for preparing this compound suspension generally exhibit serious defects. Low temperatures induce the migration of small amounts of active ingredients dissolved in the aqueous system, causing them to recrystallize on the surface of existing particles. This leads to a continuous increase in particle size, eventually forming coarse crystals—a process known as Auschwitz ripening. Simultaneously, when the formulation undergoes freeze-thaw cycles, water within the system crystallizes into ice crystals. The growth of these ice crystals exerts a strong mechanical compression on the suspended pesticide particles, disrupting the protective layer formed by conventional dispersants. This forces the particles to aggregate tightly, forming hard clumps or precipitates that are difficult to redisperse. These physical instabilities not only directly result in a significant decrease in product suspension rate, affecting the uniformity of efficacy, but also drastically reduce the fluidity of the formulation, making it viscous or even semi-solid at low temperatures, difficult to pour from packaging containers, causing great inconvenience to users and wasting active ingredients.

[0004] Currently, conventional suspension stabilization technologies largely rely on traditional polymeric dispersants. While these dispersants can provide some steric hindrance or electrostatic repulsion at room temperature, they are often insufficient to effectively inhibit crystal growth and particle aggregation under complex physicochemical environments such as low temperatures and freeze-thaw cycles. Therefore, developing a chlorantraniliprole / lufenuron compound suspension that can fundamentally inhibit low-temperature crystallization and freeze-thaw aggregation while maintaining good low-temperature fluidity is a pressing technical challenge in this field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that, under low temperature storage or freeze-thaw cycle conditions, the active ingredient particles of the existing chlorantraniliprole and lufenuron composite suspension are prone to Auschwold ripening, which leads to crystal growth and irreversible agglomeration and hard precipitation, resulting in a decrease in the physical stability of the formulation and a reduction in efficacy.

[0006] To address the aforementioned technical problems, this invention provides an innovative chlorantraniliprole and lufenuron suspension with excellent low-temperature stability, and its preparation method.

[0007] The first aspect of this invention provides a low-temperature stable chlorantraniliprole and lufenuron suspension, which comprises the following components by total mass percentage: Chlorantraniliprole: 8-12%; Lufenuron: 4-6%; Low-temperature adaptive core stabilizer: 1.5-3.0%; Surface charge modifier: 2.0-4.0%; Compound antifreeze: 5.0-8.0%; Compound thickener: 0.2-0.5%; One or more functional additives: 0.6-1.8%; The remainder is water.

[0008] In a preferred embodiment of the present invention, the low-temperature adaptive core stabilizer is a specially designed PMAA-g-(PEG-ran-PPG) ternary graft copolymer.

[0009] Its polymethyl methacrylate (PMAA) backbone serves as a hydrophobic anchoring component, with a number-average molecular weight of 10,000-20,000 g / mol; Its polyethylene glycol-polypropylene glycol random copolymer (PEG-ran-PPG) side chain serves as a hydrophilic steric hindrance part, with a number average molecular weight of 1,500-3,000 g / mol, wherein the molar ratio of polyethylene glycol (PEG) units to polypropylene glycol (PPG) units is (3:1) to (5:1).

[0010] The grafting density of the copolymer, i.e. the molar ratio of the main chain monomer to the side chain, is (10:1) to (20:1).

[0011] In another preferred embodiment of the present invention, the surface charge modifier is a modified lignin sulfonate with a sulfonation degree of 1.5-2.5 mmol / g to ensure that it has sufficient negative charge density on the particle surface.

[0012] The technical effect of the suspending agent of this invention stems from its unique, multi-level synergistic stabilization mechanism.

[0013] First, the surface charge modifier (modified lignin sulfonate) preferentially adsorbs onto the surface of the active ingredient particles, providing not only a basic electrostatic repulsion layer, but more importantly, it provides a strong electrostatic anchor point for the subsequent adsorption of the core stabilizer.

[0014] Subsequently, the low-temperature adaptive core stabilizer (PMAA-g-(PEG-ran-PPG) ternary graft copolymer) is more firmly and uniformly coated on the particle surface through the hydrophobic effect and electrostatic assistance of its PMAA backbone, thereby constructing an ordered "internal charge-external space" dual-zone stabilizing layer on the particle surface. This structure is much more stable than the adsorption layer formed by a single stabilizer.

[0015] Furthermore, at room temperature, its PEG-ran-PPG side chains fully extend in the aqueous phase, providing strong steric hindrance. When the temperature drops to near the freezing point, due to the reverse temperature dissolution property of the PPG segments, the side chains undergo reversible conformational contraction, spontaneously forming a dense, dynamic "gel-like protective layer" around the particles.

[0016] This protective layer can actively isolate particles from the forming ice crystals and effectively inhibit the migration of water and solutes at the interface, thus fundamentally inhibiting crystal growth and freeze-thaw aggregation at low temperatures.

[0017] In one specific embodiment, the composite antifreeze is a mixture of propylene glycol and glycerin in a mass ratio of (1:1) to (1:1.5).

[0018] In one specific implementation, the compound thickener is a mixture of xanthan gum and magnesium aluminum silicate in a mass ratio of (3:1) to (5:1) to construct a three-dimensional network structure with excellent thixotropic properties.

[0019] In one specific implementation, the functional additive is selected from at least one of wetting agents, defoamers, and pH adjusters.

[0020] In one specific implementation scheme, the preparation of the core stabilizer PMAA-g-(PEG-ran-PPG) ternary graft copolymer includes the following steps: Step 1: Synthesis of the macromonomer PEG-ran-PPG-MA In a 500 mL three-necked flask equipped with a stirrer, thermometer, and condenser, 150 g (approximately 0.06 mol) of hydroxyl-terminated polyethylene glycol-polypropylene glycol random copolymer (HO-(PEG-ran-PPG)-OH, where the molar ratio of PEG to PPG units is approximately 4:1) with a number average molecular weight of 2500 g / mol and 200 mL of anhydrous toluene were added. The mixture was heated to 50 °C and stirred until completely dissolved. After cooling to room temperature, 7.3 g (approximately 0.072 mol) of triethylamine was added as an acid-binding agent. Under an ice-water bath, 7.5 g (approximately 0.072 mol) of methacryloyl chloride was added dropwise, with the temperature controlled not exceeding 15 °C during the addition. After the addition was complete, the mixture was allowed to return to room temperature and reacted for 10–12 hours. After the reaction was complete, the generated triethylamine hydrochloride was removed by filtration. The filtrate was then evaporated under reduced pressure on a rotary evaporator to remove toluene, yielding a pale yellow viscous liquid. The product was dissolved in 200 mL of dichloromethane, washed three times each with saturated sodium bicarbonate solution and deionized water, dried with anhydrous magnesium sulfate, filtered, and the filtrate was precipitated in a large amount (about 2000 mL) of ice-cold diethyl ether. The precipitation and purification were repeated 2-3 times. Finally, the product was dried to constant weight in a vacuum oven at 40 °C to obtain the methacrylate-terminated polyethylene glycol-polypropylene glycol random copolymer (PEG-ran-PPG-MA).

[0021] Step 2: Synthesis of PMAA-g-(PEG-ran-PPG) terpolymer In a 500 mL three-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen delivery tube, 25 g (approximately 0.01 mol) of the PEG-ran-PPG-MA macromonomer prepared in step one, 15 g (approximately 0.15 mol) of methyl methacrylate (MMA), and 0.2 g of azobisisobutyronitrile (AIBN) as an initiator were added, along with 250 mL of toluene as a solvent. Nitrogen gas was purged for 30 minutes to remove oxygen from the system. Subsequently, under nitrogen protection, the reaction system was heated to 70-75 °C and reacted at this temperature for 8-10 hours. After the reaction was completed, the reaction solution was cooled to room temperature and slowly added dropwise to 2500 mL of petroleum ether (or n-hexane) with vigorous stirring, resulting in the precipitation of a white precipitate. The precipitate was collected by filtration, washed several times with petroleum ether, and then dried in a vacuum oven at 45 °C for 24 hours to constant weight, yielding the target product, PMAA-g-(PEG-ran-PPG) terpolymer. By adjusting the feeding ratio of MMA to macromonomers, the grafting density and molecular weight of the final product can be controlled to ensure that they fall within the range required by this invention.

[0022] In one specific implementation, the preparation of lignin sulfonate modified with a surface charge modifier includes the following steps: 100g of industrial lignin (such as alkali lignin) was dispersed in 500mL of water, and 25g of sodium sulfite was added. The mixture was heated to 140-160℃ in a reaction vessel, and the pressure was maintained at 0.4-0.6MPa for 2-4 hours. After the reaction was completed, the temperature and pressure were reduced, and the reaction solution was filtered to remove insoluble matter. The pH of the filtrate was adjusted to 2-3 with dilute sulfuric acid, at which point lignin sulfonate precipitated. The precipitate was collected by filtration, washed until neutral, and dried to obtain modified lignin sulfonate with a sulfonation degree in the range of 1.5-2.5mmol / g.

[0023] A second aspect of this invention provides a method for preparing the aforementioned low-temperature stable chlorantraniliprole and lufenuron suspension, characterized by a specific processing sequence aimed at constructing the aforementioned composite stable structure. The method comprises the following core steps: (a) Chlorantraniliprole and lufenuron technical grade, along with functional adjuvants and compound antifreeze, are added to the aqueous phase for preliminary dispersion; (b) Under shear conditions, the modified lignin sulfonate is added to the slurry of step (a) to perform surface charge modification treatment on the active pharmaceutical ingredient particles; (c) After completing step (b), while maintaining the shear conditions, add the PMAA-g-(PEG-ran-PPG) ternary graft copolymer to the slurry to perform secondary coating on the modified particle surface and form a composite stable layer. (d) The slurry treated in step (c) is wet-milled, and then the compound thickener is added to thicken it, finally obtaining the target product.

[0024] In one specific implementation, the shearing conditions in steps (b) and (c) are as follows: using a high-speed shear disperser, shearing for 10-15 minutes and 15-20 minutes respectively at a speed of 2000-4000 rpm.

[0025] In a more specific implementation, the wet grinding process parameters in step (d) are: grinding the particle size D90 of the slurry to less than 5.0 micrometers, and controlling the slurry outlet temperature during the grinding process to be below 40°C through circulating cooling.

[0026] The key to this preparation method lies in achieving the orderly assembly of the stabilizer on the particle surface through the sequential steps (b) and (c), which is a necessary process guarantee for obtaining the excellent low-temperature stability described in this invention.

[0027] In summary, the present invention has at least one of the following beneficial technical effects: 1. This invention introduces a PMAA-g-(PEG-ran-PPG) ternary graft copolymer, which utilizes its unique low-temperature adaptive properties to actively form a dynamic "gel-like protective layer" on the particle surface at low temperatures. This protective layer effectively isolates particles from ice crystals and inhibits interfacial mass transfer, mechanistically preventing irreversible agglomeration caused by Auschwold ripening and freeze-thaw cycles, thus ensuring the long-term physical stability of the formulation under harsh low-temperature conditions.

[0028] 2. This invention utilizes a specific preparation process to first modify the surface charge of particles using modified lignin sulfonate, and then coats them with a core stabilizer, constructing a dual-zone stable structure of "internal charge-external space". This synergistic anchoring effect makes the stabilizer adsorbed more firmly, effectively resisting physical shear forces, thus maintaining a very high suspension rate even after long-term storage and avoiding the formation of hard precipitates.

[0029] 3. This invention employs a xanthan gum-magnesium aluminum silicate composite thickener and a propylene glycol-glycerin composite antifreeze agent, which work synergistically. The former provides excellent thixotropic properties, making the product highly stable when standing, while allowing it to be easily shaken before pouring; the latter creates a structured aqueous phase environment, effectively reducing the viscosity thickening effect at low temperatures, ensuring that the product still has good pourability in cold climates, facilitating accurate measurement by users. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below with reference to specific embodiments. However, it should be understood that the description herein is merely exemplary and is not intended to limit the scope of protection of this invention.

[0031] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0032] Active ingredient: Chlorantraniliprole, purity 97.5%, CAS No.: 500008-45-7.

[0033] Lufenuron, purity 97.2%, CAS No.: 103055-07-8.

[0034] Key formulation adjuvants: Polyether modified polysiloxane, wetting agent, CAS No.: 67674-67-3.

[0035] Propylene glycol, CAS No.: 57-55-6.

[0036] Glycerol, CAS No.: 56-81-5.

[0037] Xanthan gum, 200 mesh, CAS No.: 11138-66-2.

[0038] Magnesium aluminum silicate, colloidal grade, CAS No.: 1327-43-1.

[0039] Key synthetic precursors: Methyl methacrylate (MMA), CAS No.: 80-62-6.

[0040] Methacryloyl chloride, purity 97%, CAS No.: 920-46-7.

[0041] Alkali lignin, industrial grade, CAS No.: 8068-05-1.

[0042] Azobisisobutyronitrile (AIBN), initiator, CAS No.: 78-67-1.

[0043] Preparation Example 1: Preparation of hydroxyl-terminated polyethylene glycol-polypropylene glycol random copolymer The preparation of this random copolymer includes the following steps: In a 2L stainless steel high-pressure reactor equipped with a mechanical stirrer, gas inlet tube, and vacuum interface, 7.6g (0.1mol) of propylene glycol was added as an initiator and 4.0g of potassium hydroxide as a catalyst. The reactor was sealed and the mixture was stirred and dehydrated for 2 hours at 110℃ and a vacuum of -0.1MPa. After dehydration, the air inside the reactor was purged three times with high-purity nitrogen.

[0044] The reactor was heated to 120°C, and a mixed monomer consisting of 1762.0 g (40.0 mol) of ethylene oxide and 580.8 g (10.0 mol) of propylene oxide was added dropwise at a uniform rate. During the dropwise addition, the pressure inside the reactor was maintained at no more than 0.4 MPa. After the dropwise addition was completed, the reaction was continued at 120-125°C for 5 hours until the pressure inside the reactor stabilized.

[0045] The reactor was cooled to 90°C, and appropriate amounts of water and phosphoric acid were added to adjust the pH of the material to 6-7 to neutralize the catalyst. After stirring for 30 minutes, the generated potassium phosphate salt was removed by pressure filtration. The filtrate was then subjected to reduced pressure at 110°C and -0.1 MPa to remove water and low-boiling substances, finally yielding a colorless to pale yellow viscous liquid, which is a hydroxyl-terminated polyethylene glycol-polypropylene glycol random copolymer (HO-(PEG-ran-PPG)-OH) with a number average molecular weight of approximately 2500 g / mol.

[0046] Preparation Example 2: Preparation of Low-Temperature Adaptive Core Stabilizer (PMAA-g-(PEG-ran-PPG)) The preparation of this stabilizer includes the following steps: Step 1: Synthesis of the macromonomer PEG-ran-PPG-MA In a 1L three-necked flask equipped with a stirrer, thermometer, and dropping funnel, 250.0 g (0.1 mol) of the hydroxyl-terminated polyethylene glycol-polypropylene glycol random copolymer prepared in Preparation Example 1 and 300 mL of anhydrous toluene were added. The mixture was heated to 50°C and stirred until completely dissolved. After cooling to room temperature, 11.1 g (0.11 mol) of triethylamine was added. Under ice-water bath cooling, 11.5 g (0.11 mol) of methacryloyl chloride was slowly added dropwise to the flask, controlling the system temperature not to exceed 15°C during the addition. After the addition was complete, the ice bath was removed, and the reaction was continued at room temperature for 12 hours. After the reaction was completed, the generated triethylamine hydrochloride precipitate was removed by filtration. The filtrate was evaporated under reduced pressure at 60°C using a rotary evaporator to remove the solvent toluene, yielding a pale yellow viscous product, which was the methacrylate-terminated polyethylene glycol-polypropylene glycol random copolymer (PEG-ran-PPG-MA).

[0047] Step 2: Synthesis of PMAA-g-(PEG-ran-PPG) terpolymer In a 1L three-necked flask equipped with a stirrer, condenser, and nitrogen delivery tube, 52.0 g (approximately 0.02 mol) of the PEG-ran-PPG-MA macromonomer prepared in step one, 20.0 g (0.2 mol) of methyl methacrylate (MMA), and 0.4 g of azobisisobutyronitrile (AIBN) were added, along with 400 mL of toluene as a solvent. Nitrogen gas was bubbled into the system for 30 minutes to remove oxygen. Under nitrogen protection, the reaction system was heated to 75°C and reacted at this temperature for 10 hours. After the reaction was complete, the reaction solution was cooled to room temperature and slowly added dropwise to 4000 mL of n-hexane with vigorous stirring, resulting in the precipitation of a white flocculent precipitate. The precipitate was collected by filtration and washed three times with n-hexane. Finally, it was dried in a vacuum oven at 45°C for 24 hours to constant weight to obtain the target product, PMAA-g-(PEG-ran-PPG) terpolymer.

[0048] Preparation Example 3: Preparation of Surface Charge Modifier (Modified Lignosulfonate) In a 1L high-pressure reactor, 100g of alkali lignin (industrial grade) was dispersed in 500mL of water, followed by the addition of 25g of sodium sulfite. The reactor was sealed, stirring was started, and the temperature inside the reactor was raised to 150℃. The reaction was carried out under these conditions for 3 hours, with the pressure maintained at approximately 0.5MPa. After the reaction was completed, the reactor was cooled to room temperature and the pressure was released. The slurry in the reactor was filtered to remove a small amount of insoluble matter. Then, the pH of the filtrate was slowly adjusted to 2.5 with 20% dilute sulfuric acid, at which point a large amount of brown solid precipitate formed. The solid precipitate was collected by filtration and repeatedly washed with deionized water until the filtrate was neutral. The washed filter cake was dried in an oven at 80℃ to constant weight, and then pulverized to obtain modified lignin sulfonate powder with the required degree of sulfonation.

[0049] Example 1: The suspending agent of this embodiment comprises the following components by mass percentage: chlorantraniliprole (purity 97.5%) 10.0%; lufenuron (purity 97.2%) 5.0%; core stabilizer (product of Preparation Example 2) 2.0%; surface charge modifier (product of Preparation Example 3) 3.0%; propylene glycol 3.5%; glycerin 3.5%; xanthan gum 0.3%; magnesium aluminum silicate 0.1%; polyether-modified silicone (wetting agent) 0.5%; silicone defoamer 0.3%; pH adjuster 0.2%; and deionized water, with the remainder to 100%.

[0050] 2. Preparation method (a) Add the prescribed amounts of deionized water, propylene glycol and glycerin to the mixing tank, start stirring, and then add chlorantraniliprole technical, lufenuron technical, wetting agent and defoamer in sequence. Pre-disperse the mixture for 15 minutes at 1500 rpm in a high-speed shear disperser to form a uniform initial slurry.

[0051] (b) While stirring, slowly add the formulated amount of surface charge modifier (the product of Preparation Example 3) into the slurry, and then increase the shear speed to 3000 rpm and shear for 15 minutes to perform surface modification.

[0052] (c) Continue shearing at 3000 rpm and slowly add the formulated amount of core stabilizer (product of Preparation Example 2) to the slurry, and continue shearing for 20 minutes to coat.

[0053] (d) The slurry processed by the above steps is pumped into a horizontal sand mill for wet grinding. The discharge temperature is controlled below 40°C by circulating cooling water until the particle size D90 of the slurry is less than 3 micrometers.

[0054] (e) The xanthan gum and magnesium aluminum silicate of the specified amounts are pre-prepared into a thickening gel in a small amount of water. The ground slurry is pumped into a thickening vessel, the thickening gel is added, and the pH of the system is adjusted to 6.5 with a pH adjuster. The mixture is stirred slowly until homogeneous to obtain the suspension product of this embodiment.

[0055] Example 2: 1. Formula Composition The suspending agent of this embodiment comprises the following components by mass percentage: chlorantraniliprole (97.5% purity) 8.0%; lufenuron (97.2% purity) 4.0%; core stabilizer (product of Preparation Example 2) 1.5%; surface charge modifier (product of Preparation Example 3) 2.0%; propylene glycol 2.5%; glycerin 2.5%; xanthan gum 0.2%; magnesium aluminum silicate 0.05%; polyether-modified silicone (wetting agent) 0.4%; silicone defoamer 0.2%; pH adjuster 0.1%; and deionized water, with the remainder to 100%.

[0056] 2. Preparation method The preparation method is the same as in Example 1, except that the shearing speed in steps (b) and (c) is 2000 rpm; and the grinding target in step (d) is a particle size D90 of less than 5 micrometers.

[0057] Example 3: 1. Formula Composition The suspending agent of this embodiment comprises the following components by mass percentage: chlorantraniliprole (purity 97.5%) 12.0%; lufenuron (purity 97.2%) 6.0%; core stabilizer (product of Preparation Example 2) 3.0%; surface charge modifier (product of Preparation Example 3) 4.0%; propylene glycol 3.2%; glycerin 4.8%; xanthan gum 0.4%; magnesium aluminum silicate 0.08%; polyether-modified silicone (wetting agent) 1.0%; silicone defoamer 0.5%; pH adjuster 0.3%; and deionized water, with the remainder to 100%.

[0058] 2. Preparation method The preparation method is the same as in Example 1, except that the shearing speed in steps (b) and (c) is 4000 rpm; and the grinding target in step (d) is a particle size D90 of less than 2.5 micrometers.

[0059] Example 4: 1. Formula Composition The suspending agent of this embodiment comprises the following components by mass percentage: chlorantraniliprole (purity 97.5%) 10.0%; lufenuron (purity 97.2%) 5.0%; core stabilizer (product of Preparation Example 2) 2.5%; surface charge modifier (product of Preparation Example 3) 2.5%; propylene glycol 2.4%; glycerol 3.6%; xanthan gum 0.32%; magnesium aluminum silicate 0.08%; polyether-modified silicone (wetting agent) 0.8%; silicone defoamer 0.4%; pH adjuster 0.2%; and deionized water, with the remainder to 100%.

[0060] 2. Preparation method The preparation method is the same as in Example 1.

[0061] Comparative Example 1: 1. Formula Composition The suspension concentrate of this comparative example has the following mass percentages of each component: chlorantraniliprole (purity 97.5%) 10.0%; lufenuron (purity 97.2%) 5.0%; sodium naphthalene sulfonate formaldehyde condensate (conventional dispersant) 5.0%; propylene glycol 3.5%; glycerin 3.5%; xanthan gum 0.3%; magnesium aluminum silicate 0.1%; polyether-modified silicone (wetting agent) 0.5%; silicone defoamer 0.3%; pH adjuster 0.2%; deionized water, with the balance to 100%.

[0062] 2. Preparation method The prescribed amounts of deionized water, propylene glycol, glycerin, chlorantraniliprole, lufenuron, sodium naphthalene sulfonate formaldehyde condensate, wetting agent, and defoamer are added to a mixing tank in one batch and dispersed at 3000 rpm for 30 minutes using a high-speed shear disperser. The slurry is then pumped into a horizontal sand mill for grinding, controlling the discharge temperature below 40°C, until the particle size D90 is less than 3 micrometers. Finally, the ground slurry is pumped into a thickening tank, a pre-prepared thickening gel is added, the pH is adjusted to 6.5, and the mixture is thoroughly mixed to obtain the final product.

[0063] Comparative Example 2: 1. Formula Composition The formulation of this comparative example is exactly the same as that of Example 1, except that the 2.0% of "core stabilizer (product of preparation example 2)" in Example 1 is replaced with an equal amount of "polymethyl methacrylate-g-polyethylene glycol (PMAA-g-PEG) graft copolymer".

[0064] Note: The PMAA-g-PEG graft copolymer described above is prepared in a similar manner to that in Preparation Example 2, except that in step one, hydroxyl-terminated polyethylene glycol (HO-PEG-OH), which has a number-average molecular weight similar to that of the product in Preparation Example 1, is used as the starting material for synthesis.

[0065] 2. Preparation method The preparation method is exactly the same as in Example 1, strictly following the same step-by-step feeding and shearing coating process.

[0066] Comparative Example 3: 1. Formula Composition The formulation of this comparative example is basically the same as that of Example 1, but it does not contain the "surface charge modifier (product of Preparation Example 3)", and its mass percentage is made up by deionized water. That is, the mass percentage of each component is: chlorantraniliprole 10.0%; lufenuron 5.0%; core stabilizer (product of Preparation Example 2) 2.0%; propylene glycol 3.5%; glycerin 3.5%; xanthan gum 0.3%; magnesium aluminum silicate 0.1%; wetting agent 0.5%; defoamer 0.3%; pH adjuster 0.2%; deionized water, with the balance made up to 100%.

[0067] 2. Preparation Method: Since no surface charge modifier is present, step (b) of Example 1 is omitted from the preparation method. Specifically, after the initial slurry is formed (step (a)), the core stabilizer (product of Preparation Example 2) is directly added to the slurry, and sheared at 3000 rpm for 20 minutes (corresponding to step (c) of Example 1). The subsequent grinding and thickening steps are the same as in Example 1.

[0068] Test Example 1: 1. Experimental Objectives and Methods This test aims to evaluate the ability of formulations to inhibit the precipitation and growth of active ingredient crystals and maintain the physical homogeneity of the system under sustained low-temperature conditions. The test was conducted in accordance with GB / T 19137-2003 "Determination of Low-Temperature Stability of Pesticides".

[0069] 2. Test procedure (1) Take 100 mL of each of the samples from Examples 1 to 4 and Comparative Examples 1 to 3, and put them into clean, dry 100 mL stoppered graduated cylinders and seal them.

[0070] (2) Place all the graduated cylinders containing the samples in a constant temperature test chamber at -10℃±1℃ and store them for 7 days.

[0071] (3) After the storage period is over, take out all the graduated cylinders and let them naturally return to room temperature at 20℃±2℃.

[0072] (4) After returning to room temperature, first visually inspect the appearance of each sample and record whether there are any phenomena such as layering, crystallization, or clumping.

[0073] (5) Tighten the measuring cylinder cap and invert it 30 times at a rate of 30 times per minute to mix the contents evenly.

[0074] (6) After mixing, use a pipette to accurately transfer the upper 9 / 10 volume (i.e., 90 mL) of the suspension.

[0075] (7) The total mass (m1) of the active ingredients in the original sample and the mass (m2) of the active ingredients in the 90 mL suspension were determined by high performance liquid chromatography (HPLC).

[0076] (8) Calculate the suspension rate of each sample according to the formula: suspension rate (%) = (m2 / (0.9×m1))×100.

[0077] 3. Test Results Table 1 Results of low-temperature storage stability tests for each sample Sample number Appearance observation Suspension rate (%) Example 1 The system is homogeneous and stable, with no precipitation or agglomeration. 98.7 Example 2 The system is homogeneous and stable, with no precipitation or agglomeration. 97.9 Example 3 The system is homogeneous and stable, with no precipitation or agglomeration. 98.2 Example 4 The system is homogeneous and stable, with no precipitation or agglomeration. 98.5 Comparative Example 1 There is a hard mass at the bottom, with a small number of needle-like crystals visible. 54.3 Comparative Example 2 There is obvious soft sediment at the bottom, and the supernatant is slightly turbid. 76.5 Comparative Example 3 The system exhibits clear stratification, with a clear supernatant and crystals at the bottom. 61.8 4. Results Analysis As shown in Table 1, the suspending agents prepared in Examples 1-4 maintained a homogeneous and stable state after low-temperature storage, with no visible precipitation or agglomeration, and the suspension rate remained at an extremely high level. In contrast, the comparative examples exhibited varying degrees of stability problems, such as hard agglomeration, significant crystallization, and a substantial decrease in suspension rate. This fully demonstrates the significant superiority of the technical solution provided by this invention in terms of low-temperature stability.

[0078] This superior performance is attributed to the PMAA-g-(PEG-ran-PPG) terpolymer used. At low temperatures, the polypropylene glycol (PPG) segments on the copolymer side chains undergo conformational shrinkage due to reduced water solubility, tending to form a dense and dynamic gel-like physical barrier at the solid-liquid interface. This barrier effectively prevents direct contact between the dispersed active ingredient particles and the surrounding continuously forming ice crystals, fundamentally inhibiting mass transfer processes mediated by ice crystals. This prevents crystal growth and aggregation caused by Auschwitz ripening, ensuring the physical integrity of the formulation.

[0079] Furthermore, the specific preparation process employed in this invention is key to achieving this stabilizing effect. By pretreating the particles with a surface charge modifier, their surfaces acquire a negative charge, providing a robust electrostatic anchoring point for the subsequent adsorption of the core stabilizer. This synergistic stabilization mechanism of "internal charge-external steric hindrance" constructs an extremely robust composite adsorption layer, making it difficult for the core stabilizer to detach even under the physical disturbances of low-temperature freeze-thaw cycles. This allows it to continuously and effectively exert its steric hindrance and interfacial isolation functions, ultimately endowing the product with low-temperature storage stability exceeding that of conventional formulations.

[0080] Test Example 2: 1. Experimental Objectives and Methods This test aims to evaluate the formulation's ability to resist particle aggregation and sedimentation, and to maintain a stable suspension state under conditions of drastic temperature changes. The test was conducted in accordance with GB / T 43273-2023, "Determination of Freeze-Thaw Stability of Pesticides".

[0081] 2. Experimental steps (1) Take 50 mL of each of the samples from Examples 1 to 4 and Comparative Examples 1 to 3, and put them into clean, dry 100 mL stoppered graduated cylinders, and record the sample height.

[0082] (2) Place all samples in a constant temperature low temperature chamber at -5℃±1℃ for 18 hours.

[0083] (3) After taking it out, immediately transfer it to a constant temperature water bath at 30℃±1℃ and keep it for 6 hours. This is one freeze-thaw cycle.

[0084] (4) Repeat steps (2) and (3) for a total of 5 freeze-thaw cycles.

[0085] (5) After the cycle is completed, all samples are restored to room temperature at 20℃±2℃.

[0086] (6) After returning to room temperature, first visually inspect the appearance of each sample and record whether there are any phenomena such as layering, clumping, or particle aggregation.

[0087] (7) Determine and calculate the suspension rate of each sample according to the method in steps (5) to (8) of Test Example 1.

[0088] 3. Test Results Table 2 Results of freeze-thaw cycle stability tests for each sample Sample number Appearance observation Suspension rate (%) Example 1 The system is uniform and stable with good liquidity. 97.2 Example 2 The system is uniform and stable with good liquidity. 96.8 Example 3 The system is uniform and stable with good liquidity. 97.5 Example 4 The system is uniform and stable with good liquidity. 97.1 Comparative Example 1 There are a large number of hard lumps at the bottom, and the supernatant is clear. 48.9 Comparative Example 2 There was obvious particle aggregation and soft sediment at the bottom. 68.1 Comparative Example 3 A visible sediment layer with a small amount of aggregates is present at the bottom. 59.5 4. Results Analysis The experimental data in Table 2 show that the suspending agents prepared in Examples 1-4 of this invention maintain excellent physical stability and high suspension rate even after repeated freeze-thaw cycles. In contrast, all comparative examples exhibited severe stability problems, including hardening, clumping, particle aggregation, and a sharp decrease in suspension rate. This demonstrates the effectiveness of the technical solution of this invention in resisting sudden temperature changes.

[0089] This freeze-thaw stability lies in the unique low-temperature adaptive molecular conformation of the core stabilizer. During the cooling and freezing process, the formation and growth of ice crystals within the system exerts strong mechanical compressive stress on the dispersed active ingredient particles. The polypropylene glycol (PPG) segments on the side chains of the stabilizer in this invention change from an extended hydrophilic state to a contracted hydrophobic state at low temperatures, forming a dense, gel-like protective layer on the particle surface that combines toughness and elasticity. This dynamically formed buffer layer effectively absorbs the physical stress caused by ice crystal growth, acting like a "buffer pad" for the particles and preventing irreversible hard agglomeration between them.

[0090] More importantly, this invention does not rely solely on the single function of the core stabilizer, but achieves precise synergy among the components through a specific preparation process. First, a robust negatively charged layer is constructed on the particle surface using a surface charge modifier, providing a strong electrostatic adsorption anchor for the subsequent graft copolymerization of the core stabilizer. This pre-constructed anchoring foundation ensures that the sterically hindered polymer segments of the outer layer do not detach from the particle surface under the severe disturbances of freeze-thaw cycles. The failure of Comparative Example 3 (lacking the charge modifier) ​​precisely demonstrates the importance of this dual stabilizing structure of "internal charge-external steric hindrance." It is this robust composite protective layer that collectively endows the formulation with the ability to resist extreme temperature changes and maintain long-term stability.

[0091] Test Example 3: 1. Experimental Objectives and Methods This test aims to directly verify the effectiveness of the technical solution of this invention in inhibiting particle growth (especially crystals at low temperatures) through quantitative data. The physical stability of the sample is visually evaluated by comparing the changes in particle size before and after low-temperature and freeze-thaw stability tests.

[0092] 2. Test steps (1) Take the initial samples of Examples 1 to 4 and Comparative Examples 1 to 3 respectively, as well as the samples that have been treated by Test Example 1 (stored at -10℃ for 7 days) and Test Example 2 (5 freeze-thaw cycles) and then restored to room temperature.

[0093] (2) Take an appropriate amount of the sample to be tested, dilute it with deionized water to the appropriate concentration range of the instrument, and sonicate it slightly for 1 minute to ensure that the sample is evenly dispersed in the measuring cell.

[0094] (3) Use a laser particle size analyzer, set appropriate refractive index and absorptivity parameters, and measure each sample.

[0095] (4) Record the volume-weighted cumulative distribution particle size D90 value for each sample. This value indicates that 90% of the volume of particles have a particle size smaller than this value.

[0096] 3. Test Results Table 3. Changes in particle size (D90) of each sample before and after stability testing. 4 Results Analysis The quantitative data in Table 3 reveal the differences in stability among different technical solutions. The samples from Examples 1-4 of this invention showed only a negligible increase in D90 particle size after low-temperature storage and freeze-thaw cycles, demonstrating the extremely high stability of their particle systems. In contrast, all comparative samples showed a dramatic increase in particle size, exceeding tens of times, indicating severe and irreversible crystal growth and hard agglomeration within them. This result fundamentally verifies the superior performance of the technical solution of this invention in suppressing particle growth.

[0097] The core mechanism behind this superior particle size stabilization lies in the unique molecular behavior of the low-temperature adaptive core stabilizer. The polypropylene glycol (PPG) portion on the stabilizer's side chain exhibits thermosensitive properties; at low temperatures, its water solubility significantly decreases, causing the chain segments to shrink and form a physically dense gel-like insulating layer on the particle surface. This dynamically formed insulating layer physically blocks the mass exchange channels between the particle surface and the aqueous medium, effectively suppressing the main driving force for crystal growth—the Austrowald ripening process. The significant particle size increase in Comparative Example 2 (lacking PPG segments) precisely demonstrates that this "low-temperature adaptive" characteristic is key to suppressing crystal growth.

[0098] Furthermore, the technical solution of this invention does not rely solely on a single component of the stabilizer, but rather originates from a precise synergistic stabilization system. The failure of Comparative Example 3 (lacking a surface charge modifier) ​​fully demonstrates the necessity of the preparation process of this invention. By pre-adsorbing the surface charge modifier, a negatively charged layer is constructed on the particle surface, providing electrostatic anchoring points for the subsequent coating of the core stabilizer. This composite structure of "internal charge-external steric hindrance" ensures that the stabilizing layer will not desorb under physical stress impacts such as freeze-thaw cycles, thus enabling it to exert its isolation and protective functions for a long time, ultimately achieving effective control over particle size and endowing the formulation with exceptional physical stability.

[0099] Test Example 4: 1. Experimental Objectives and Methods This test aims to evaluate the actual flowability and operability of the formulation under low-temperature conditions, simulating application scenarios in cold climates. The test was conducted in accordance with the provisions of GB / T 31737-2015 "Determination of Pesticide Dumping Properties", but all operational steps were completed under low-temperature conditions.

[0100] 2. Test procedure (1) Place the samples of Examples 1 to 4 and Comparative Examples 1 to 3, sufficient deionized water for rinsing, and clean and dry beakers and sample containers in a constant temperature environment of 5℃±1℃ for at least 4 hours for pretreatment.

[0101] (2) In this low-temperature environment, weigh the mass (m0) of a clean and dry sample container. Add about 100g of the sample to be tested into the container and accurately weigh the total mass (m1) of the container containing the sample.

[0102] (3) Pour the sample from the container into a clean beaker that has been placed on a balance at a steady flow rate for 60 seconds.

[0103] (4) After pouring, invert the sample container over the beaker and hold it for 10 seconds to let it drip dry.

[0104] (5) Return the sample container with residue to the balance and weigh its mass (m2).

[0105] (6) Calculate the percentage of residue by mass. The formula is: Residue (%) = [(m2-m0) / (m1-m0)] × 100.

[0106] 3. Test Results Table 4. Results of Low-Tilting Performance Tests for Each Sample Sample number Residue (%) Example 1 0.28 Example 2 0.35 Example 3 0.24 Example 4 0.31 Comparative Example 1 12.7 Comparative Example 2 6.8 Comparative Example 3 9.3 4. Results Analysis The test results in Table 4 demonstrate the significant advantages of the present invention's technical solution in low-temperature application performance. The samples in Examples 1-4 all exhibited excellent flowability at 5°C, with container residues all below 0.4%, indicating that they could be easily and completely poured out. Conversely, all comparative samples showed high residue rates, meaning they became viscous and had poor flowability at low temperatures, making them difficult to pour out of the container. This would result in waste of the active ingredient and inconvenience in practical applications.

[0107] The excellent low-temperature pourability of the formulation of this invention is fundamentally due to the fact that the formulation system can maintain low viscosity and good flowability at low temperatures. This is thanks to the low-temperature adaptive properties of the polypropylene glycol (PPG) segments in the core stabilizer. In a low-temperature environment, the dynamic gel-like protective layer formed by the PPG segments not only prevents particle aggregation, but more importantly, it effectively inhibits the sharp increase in system viscosity caused by the enhanced interparticle forces. This protective layer acts like a microscopic "liquid bearing," ensuring that even at low temperatures, the dispersed particles can move smoothly, thus maintaining the entire suspension system in a flow state similar to that at room temperature, rather than forming a semi-solidified gel.

[0108] Furthermore, this excellent flowability also relies on the synergistic stabilizing structure constructed in this invention. The high residue rate of Comparative Example 3 (lacking the charge modifier) ​​indicates that without the robust electrostatic anchoring provided by the surface charge modifier, the core stabilizer may partially desorb under the shear force of pouring, leading to particle exposure and adhesion to the container wall, thus hindering smooth flow. This invention, through a precise design of "internal charge-external steric hindrance," constructs an exceptionally robust composite protective layer. This layer is stable not only during static storage but also remains intact during dynamic pouring, thereby ensuring excellent low-temperature flowability and extremely low container residue, demonstrating its significant application value in cold regions.

[0109] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-temperature stable chlorantraniliprole and lufenuron suspension, characterized in that, The suspending agent comprises the following components by total mass percentage: Chlorantraniliprole: 8-12%; Lufenuron: 4-6%; Low-temperature adaptive core stabilizer: 1.5–3.0%; Surface charge modifier: 2.0–4.0%; Compound antifreeze: 5.0–8.0%; Compound thickener: 0.2-0.5%; One or more functional additives: 0.6–1.8%; The remainder is water; The low-temperature adaptive core stabilizer is a PMAA-g-(PEG-ran-PPG) ternary graft copolymer; The surface charge modifier is a modified lignin sulfonate.

2. The low-temperature stable chlorantraniliprole and lufenuron suspension according to claim 1, characterized in that, The structural parameters of the PMAA-g-(PEG-ran-PPG) ternary graft copolymer are as follows: The number-average molecular weight of the polymethyl methacrylate backbone is 10,000–20,000 g / mol; The number-average molecular weight of the side chains of the polyethylene glycol-polypropylene glycol random copolymer is 1,500 to 3,000 g / mol. The molar ratio of polyethylene glycol units to polypropylene glycol units in the side chain is (3:1) to (5:1); The grafting molar ratio of the main chain monomer to the side chain is (10:1) to (20:1).

3. The low-temperature stable chlorantraniliprole and lufenuron suspension according to claim 1, characterized in that, The degree of sulfonation of the modified lignin sulfonate is 1.5–2.5 mmol / g.

4. The low-temperature stable chlorantraniliprole and lufenuron suspension according to claim 1, characterized in that, The composite antifreeze is a mixture of propylene glycol and glycerin in a mass ratio of (1:1) to (1:1.5); the compound thickener is a mixture of xanthan gum and magnesium aluminum silicate in a mass ratio of (3:1) to (5:1).

5. The low-temperature stable chlorantraniliprole and lufenuron suspension according to claim 1, characterized in that, The functional additive is selected from at least one of wetting agents, defoamers, and pH adjusters.

6. A method for preparing a low-temperature stable chlorantraniliprole and lufenuron suspension according to any one of claims 1-5, characterized in that, Includes the following steps: (a) Chlorantraniliprole and lufenuron technical grade were initially dispersed in an aqueous phase; (b) Under shear conditions, modified lignin sulfonate is added to the slurry of step (a) to modify the surface charge of the active pharmaceutical ingredient particles; (c) After completing step (b), PMAA-g-(PEG-ran-PPG) ternary graft copolymer is added to the slurry under shear conditions to coat the modified particle surface and form a composite stable layer. (d) The slurry treated in step (c) is wet-milled, and then a compound thickener is added to thicken it.

7. The preparation method according to claim 6, characterized in that, In step (b), the shearing conditions are shearing at a rotation speed of 2000-4000 rpm for 10-15 minutes.

8. The preparation method according to claim 6, characterized in that, In step (c), the shearing condition is to continue shearing for 15 to 20 minutes at a rotation speed of 2000 to 4000 rpm.

9. The preparation method according to claim 6, characterized in that, The wet grinding in step (d) involves grinding the particle size D90 of the slurry to less than 5.0 micrometers, and controlling the slurry outlet temperature below 40°C during the grinding process.

10. The preparation method according to claim 6, characterized in that, The functional additives and composite antifreeze agents are added to the aqueous phase before or during step (a).

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