BR102022012950A2 - SUSPENSION CONCENTRATE CONTAINING TERBUTHYLAZINE AND PYROXASULFONE AND METHOD OF PREPARATION THEREOF - Google Patents

Abstract

suspension concentrate containing terbuthylazine and pyroxasulfone and method of preparation thereof. The present invention relates to a suspension concentrate containing terbuthylazine and pyroxasulfone, which comprises: in mass content, 40%~60% of an active ingredient, 4%~10% of a dispersant, 1%~5% of an agent wetting agent, 0.1%~4% of a thickener, and 0.2%~3% of an antifoam agent; The active ingredient comprises terbuthylazine and pyroxasulfone. In the present disclosure, terbuthylazine and pyroxasulfone are compounds in a suspension concentrate, which leads to the expansion of their herbicide spectrum. Through the selection and optimization of the dispersant, problems such as high viscosity, creaminess and agglomeration of the product during storage are effectively solved, and through the selection and optimization of the wetting agent and anti-freezing agent, the problem of peeling of the product product is resolved, and the stability of the product under low temperature conditions is improved, thereby overcoming the technical difficulties of high content suspension concentrate. The prepared suspension concentrate ensures a high suspension rate in water, and increases retentivity on the plant surface by adding a suitable wetting agent, thereby leading to more pronounced effectiveness, and simultaneously reducing environmental pollution caused by the pesticide.

Description

FIELD OF TECHNIQUE

[001] The present disclosure relates to the technical field of pesticides and, particularly, relates to a suspension concentrate containing terbuthylazine and pyroxasulfone and a method of preparing the same.

BACKGROUND OF THE TECHNIQUE

[002] Terbuthylazine, with a chemical name of 2-chloro-4-tert-butylamino-6-ethylamino-1,3,5-triazine, is a selective systemic herbicide. It can be absorbed by the roots before germination, or infiltrated into plants through the stems and leaves and transported to green leaves to inhibit photosynthesis. In general, it has a better effect on newly germinated weeds. It can be applied to crops such as corn, sorghum, soybeans, seed fruit trees, citrus fruits and grapes in order to control annual broadleaf and grass weeds with an effect on broadleaf weeds better than that on grasses. grass weeds, and a weak effect on perennial weeds.

[003] Terbuthylazine has a high application rate if used individually and cannot effectively control broadleaf weeds.

SUMMARY

[004] In view of the foregoing, the technical problem to be solved by the present disclosure is to provide a suspension concentrate containing terbuthylazine and pyroxasulfone and a method of preparing the same. The prepared suspension concentrate has high stability.

[005] The present disclosure provides a suspension concentrate containing terbuthylazine and pyroxasulfone, comprising, in mass content: 40%~60% of an active ingredient, 4%~10% of a dispersant, 1%~5% of an agent wetting agent, 0.1%~4% of a thickener, and 0.2%~3% of an antifoam agent; wherein the active ingredient comprises terbuthylazine and pyroxasulfone.

[006] Pyroxasulfone, with a chemical name of 3- [5-(difluoromethoxy)-1-methyl-3- (trifluoromethyl)pyrazol-4-ylmethylsulfonyl]-4,5-dihydro-5,5-dimethyl-1 ,2-isoxazole, is a novel isoxazole herbicide and is widely used on crops such as corn, cotton, peanuts, wheat, sunflower. It can effectively control grass weeds such as Setaria, Digitaria and Echinochloa, and broadleaf weeds such as Amaranthus, Datura, Solanum and Abutilon.

[007] In the present disclosure, terbuthylazine and pyroxasulfone are compounds, which exert the synergistic effect of the two, to obtain a suspension concentrate. In the production and preparation process of the suspension concentrate, since terbuthylazine and pyroxasulfone have different properties, in which terbuthylazine has strong lipophilicity and there is a risk of particle aggregation in the formulation, while pyroxasulfone has a high density and there is a risk of sedimentation in the formulation, it is difficult to mix the two as a high content aqueous suspension concentrate. What's more, due to the high content and low water content, it is difficult to wet and mix the slurry. Furthermore, in high-content suspension concentrate, the wetting dispersant fails to be well adsorbed on the surface of the active ingredient particles or evenly dispersed, resulting in high viscosity of the system and peeling on the surface layer. Furthermore, in high-concentration suspension concentrate, the probability of particle movement and collision is greater than that of low-concentration suspension concentrate, the intermolecular distance is short, and the particles are aggregated in such a way that the product is prone to peeling and clumping during storage and poor product liquidity. In order to solve the above problems, the present disclosure adjusts the composition and proportion of the auxiliary agents to a specific suspension concentrate, which finally solves the problems of peeling and agglomeration, and ensures the stability of the formulation under low temperature conditions.

[008] In the present disclosure, the suspension concentrate containing terbuthylazine and pyroxasulfone may additionally comprise an anti-freezing agent and/or a preservative.

[009] The mass content of the antifreeze agent is preferably 3%~10%.

[010] The mass content of the preservative is preferably 0.1%~2%.

[011] Preferably, the suspension concentrate containing terbuthylazine and pyroxasulfone comprises, by mass content: 40%~60% of an active ingredient, 4%~10% of a dispersant, 1%~5% of a wetting agent, 0.1%~4% of a thickener, 0.2%~3% of an antifoam agent, 3%~10% of an antifreeze agent, 0.1%~2% of a preservative, and deionized water supplementing up to 100 %.

[012] The active ingredient comprises terbuthylazine and pyroxasulfone.

[013] The mass ratio of terbuthylazine to pyroxasulfone is preferably (1~11): 1, more preferably (1~6): 1, more preferably (1~4.5): 1, specifically 1:1, 1, 5:1, 2.67:1, 4.5:1, 9:1, 10:1, 11:1, or a value in the range with any of the values displayed as the upper or lower limit.

[014] The mass content of terbuthylazine is preferably 20%~55%, more preferably 20%~45%, specifically 20%, 30%, 40%, 45%, 50%, 55%, or a value in the range with any of the values displayed as the upper or lower limit.

[015] The mass content of pyroxasulfone is preferably 5%~20%, more preferably 10%~20%, specifically 5%, 10%, 15%, 20%, or a value in the range with any of the values set forth as the upper or lower limit.

[016] The dispersant content is preferably 4%~10%, more preferably 4%~8%, specifically 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a value in the range with any of the displayed values as the upper or lower limit.

[017] The dispersant is preferably selected from the group consisting of lignosulfonate, triethanolamine salt of tristyrylphenol polyoxyethylene ether phosphate, styrene copolymer - acrylic acid, sodium salt of the copolymer in styrene and maleic anhydride, condensed alkylnaphthalene sulfonate - formaldehyde , ammonium salt of tristyrylphenol polyoxyethylene ether sulfate, methyl methacrylate copolyoxyethylene ether, and a mixture thereof; more preferably selected from the group consisting of lignosulfonate, styrene-acrylic acid copolymer, methyl methacrylate copolyoxyethylene ether, triethanolamine salt of tristyrylphenol polyoxyethylene ether sulfate, ammonium salt of tristyrylphenol polyoxyethylene ether sulfate, condensed alkylnaphthalene sulfonate-formaldehyde, and a mixture thereof; further preferably, a mixed dispersant of methyl methacrylate copolyoxyethylene ether and ammonium salt of tristyrylphenol polyoxyethylene ether sulfate, and the mass ratio of methyl methacrylate copolyoxyethylene ether to ammonium salt of tristyrylphenol polyoxyethylene ether sulfate is preferably 1:(1~5), more preferably 1:2.

[018] Preferably, in the present disclosure, the dispersant comprises a first dispersant and a second dispersant, and the first dispersant is selected from the group consisting of lignosulfonate, triethanolamine salt of tristyrylphenol polyoxyethylene ether phosphate, and ammonium salt of tristyrylphenol polyoxyethylene ether sulfate; and the second dispersant is selected from the group consisting of styrene-acrylic acid copolymer, condensed alkylnaphthalene sulfonate-formaldehyde, and methyl methacrylate copolyoxyethylene ether.

[019] The mass ratio of the first dispersant to the second dispersant is preferably (1~2):1, specifically 1:1, 1.67:1 or 2:1.

[020] In some specific embodiments of the present disclosure, the dispersant is selected from the combination of 2% lignosulfonate + styrene copolymer - 2% acrylic acid.

[021] In some specific embodiments of the present disclosure, the dispersant is selected from the combination of triethanolamine salt of tristyrylphenol polyoxyethylene ether sulfate 5% + condensed alkylnaphthalene sulfonate - formaldehyde 3%.

[022] In some specific embodiments of the present disclosure, the dispersant is selected from the combination of tristyrylphenol ammonium salt polyoxyethylene ether sulfate 4% + methyl methacrylate copolyoxyethylene ether 2%.

[023] The mass content of the wetting agent is preferably 1%~5%, specifically 1%, 2%, 3%, 4%, 5%, or a value in the range with any of the values set forth as the upper limit or lower.

[024] The wetting agent is preferably selected from the group consisting of polyether propylene oxide-ethylene oxide block, polyoxyethylene ether fatty alcohol, polyoxyethylene polyoxypropylene ether fatty alcohol, polyoxyethylene ether lauryl fatty alcohol, and a mixture thereof; more preferably, propylene oxide-ethylene oxide block polyether or polyoxyethylene ether fatty alcohol; additionally preferably, 2% propylene oxide-ethylene oxide block polyether.

[025] In some specific embodiments of the present disclosure, the wetting agent is selected from 5% propylene oxide-ethylene oxide block polyether.

[026] In some specific embodiments of the present disclosure, the wetting agent is selected from 2% propylene oxide-ethylene oxide block polyether.

[027] In some specific embodiments of the present disclosure, the wetting agent is selected from 1% polyoxyethylene ether fatty alcohol.

[028] By selecting a specific dispersant and wetting agent for the composition, the present disclosure reduces the viscosity of the product and improves the stability of the formulation, which is beneficial for moistening the target plant by the formulation. A high suspension rate and moderate product viscosity effectively solve the agglomeration problem.

[029] The mass content of the thickener is preferably 0.1%~4%, specifically 0.1%, 0.15%, 1%, 3%, 4%, or a value in the range with any of the values set forth as the upper or lower limit.

[030] The thickener is preferably selected from the group consisting of magnesium aluminum silicate, organic bentonite, xanthan gum, ordinary white carbon black, and a mixture thereof, more preferably ordinary white carbon black or xanthan gum.

[031] In some specific embodiments of the present disclosure, the thickener is selected from 0.1% xanthan gum.

[032] In some specific embodiments of the present disclosure, the thickener is selected from 0.15% xanthan gum.

[033] In some specific embodiments of the present disclosure, the thickener is selected from 4% ordinary white carbon black.

[034] The mass content of the antifoam agent is preferably 0.2%~3%, more preferably 0.2%~0.5%, specifically 0.2%, 0.5%, 1%, 3%, or a value in the range with any of the values displayed as the upper or lower limit.

[035] The antifoam agent is preferably selected from the group consisting of polyether antifoam agent, organosilicon antifoam agent, polyether modified polysiloxane antifoam agent, and a mixture thereof, more preferably polyether antifoam agent or polyether antifoam agent. organosilicon.

[036] In some specific embodiments of the present disclosure, the antifoam agent is 0.5% polyether antifoam agent.

[037] In some specific embodiments of the present disclosure, the antifoam agent is 0.2% organosilicon antifoam agent.

[038] The mass content of the antifreeze agent is preferably 3%~10%, more preferably 3%~7%, specifically 3%, 4%, 5%, 7%, or a value in the range with any of the values set forth as the upper or lower limit.

[039] The antifreeze agent is preferably selected from the group consisting of urea, ethylene glycol, propylene glycol, glycerol and a mixture thereof, more preferably ethylene glycol or glycerol. In the present disclosure, by selecting a specific antifreeze agent, the product will not freeze at a low ambient temperature and has good storage stability.

[040] In some specific embodiments of the present disclosure, the antifreeze agent is selected from 3% ethylene glycol.

[041] In some specific embodiments of the present disclosure, the antifreeze agent is selected from 5% ethylene glycol.

[042] In some specific embodiments of the present disclosure, the antifreeze agent is selected from 4% glycerol.

[043] The mass content of the preservative is preferably 0.1%~2%, more preferably 0.1%~1.5%, specifically 0.1%, 0.5%, 1.5%, 2%, or a value in the range with any of the displayed values as the upper or lower limit.

[044] The preservative is preferably selected from the group consisting of Kathon, paraformaldehyde, sodium benzoate, and a mixture thereof, more preferably Kathon.

[045] In some specific embodiments of the present disclosure, the preservative is selected from 1.5% sodium benzoate.

[046] In some specific embodiments of the present disclosure, the preservative is selected from 0.1% Kathon.

[047] In some specific embodiments of the present disclosure, the preservative is selected from 0.5% paraformaldehyde.

[048] When the suspended concentrate is an aqueous suspended concentrate, the system is supplemented up to 100% with deionized water.

[049] Unless otherwise specified, the percentages in the present disclosure are all percentages by weight.

[050] The present disclosure provides a method of preparing the aforementioned suspension concentrate containing terbuthylazine and pyroxasulfone, comprising steps of: mixing a wetting agent, a dispersant, a preservative, an antifoam agent, an antifreeze agent and water uniformly, then adding a thickener and active ingredients under high-speed shear condition, mix evenly, and grind to obtain suspension concentrate containing terbuthylazine and pyroxasulfone.

[051] Preferably, in the present disclosure, the high-speed shear speed is 1,000~10,000 r/min.

[052] Preferably, in the present disclosure, after adding the thickener and active ingredient, shearing is carried out for 10~30 min to mix the system evenly.

[053] Preferably, in the present disclosure, the grinding is specifically grinding until the D90 particle size distribution of the mixture is less than 6 μm.

[054] In the present disclosure, grinding can be carried out by any grinding method disclosed in the prior art, for example, grinding can be carried out under a zirconia bead grinding medium. After milling, detection is performed using a laser particle size distribution analyzer until the D90 particle size distribution is less than 6 μm.

[055] Compared to prior technology, the present disclosure provides a suspension concentrate containing terbuthylazine and pyroxasulfone, comprising, in mass content: 40%~60% of an active ingredient, 4%~10% of a dispersant, 1% ~5% of a wetting agent, 0.1%~4% of a thickener, 0.2%~3% of an antifoam agent, 3%~10% of an anti-icing agent, and 0.1%~2% of a preservative; and the active ingredient comprises terbuthylazine and pyroxasulfone.

[056] The present disclosure is the first time to compound terbuthylazine and pyroxasulfone, and prepare them in a suspension concentrate, in which the content of the suspension concentrate of terbuthylazine and pyroxasulfone is relatively high. By composition, the active ingredient pyroxasulfone is increased, and the application rate of terbuthylazine is reduced, leading to the expansion of its herbicide spectrum. Through the selection and optimization of the dispersant, problems such as high viscosity, creaminess and agglomeration of the product during storage are effectively solved, and through the selection and optimization of the wetting agent, the problem of product peeling is solved . After production and during transportation, the product may be exposed to freezing temperatures. Freezing the concentrate in suspension can lead to irreversible changes. Therefore, whether the formulation can withstand repeated freeze-thaw processes is an important property for judging product stability. Through the selection and optimization of the anti-icing agent, the present application improves the stability of the product under low temperature conditions. The prepared suspension concentrate guarantees a high suspension rate in water, which satisfies the requirements of mechanized operation in the market. Furthermore, by adding a suitable wetting agent, the retentivity on the plant surface is increased, thereby reducing the loss of pesticides and leading to more pronounced efficacy, and simultaneously reducing environmental pollution caused by the pesticide. It has a simple, environmentally friendly and pollution-free production process, and has a good prospect for market application.

DETAILED DESCRIPTION OF THE INVENTION

[057] In order to further illustrate the present disclosure, the suspension concentrate containing terbuthylazine and pyroxasulfone and a method of preparation thereof provided by the present invention are described in detail below together with the examples.

EXAMPLES 1~7

[058] According to the ratios in tables 1~2, the wetting agent, dispersant, preservative, antifoam agent, antifreeze agent and water were mixed evenly, and then the thickener and active ingredient were added under the condition of high speed shear of 1,000~10,000 r/min for 10~30 min of shear to mix the system evenly. The system was ground until the D90 particle size distribution of the mixture was less than 6 μm, and a suspension concentrate containing terbuthylazine and pyroxasulfone was obtained.

COMPARATIVE EXAMPLE 1

[059] According to the ratio in Table 2, the suspension concentrate containing terbuthylazine and pyroxasulfone was prepared by the same method as Examples 1~7.

PERFORMANCE TEST

[060] The performances of the aqueous suspension concentrates prepared in the Exposed Examples and Comparative Example were tested, and the results are shown in Table 3 below. The suspension rate was tested according to GB/T14825-2006 suspension rate test method for pesticides; the flowability was tested in accordance with the test method GB/T31737- 2015 of flowability for pesticides; the wet sieve test was carried out according to the MT 185 test method, in which the peeling of samples was determined according to the residue after wet sieve; and the viscosity was tested according to the CIPAC MT 192 method. The freeze-thaw stability was tested as follows: the freeze-thaw stability test was carried out between room temperature (20 ± 2°C) and -10 ± 2°C for four cycles, each cycle comprising 18h of freezing and 6h of defrosting.

[061] It can be seen from Table 3 that the product of Comparative Example 1 had a relatively high viscosity, and massive peeling occurred when stored in a screw-down glass bottle at 54°C. In the wet sieve, the residual amount that did not pass through a 200 mesh sieve reached 10%. There was clumping at the base of the bottle. From the appearance, the fluidity became poor, the sample thickened, and the suspension rate also decreased significantly. The products of Examples 3, 5, 6 and 7 had a high viscosity and slightly poorer quality after hot storage. In the wet sieve, the residual amount that did not pass through a 200 mesh sieve was less than 2%, and the suspension rate was reduced, which conformed to the FAO standard. Examples 1, 2, and 4 were of good quality. The samples of Examples 1 and 2 have good fluidity at room temperature and little peeling after hot storage, which was less than 1%. Among them, Example 4 had the best quality. In the freeze-thaw stability test, the suspension rates of Examples 2, 3, and 7 were relatively low, fluidity recovery was good in Examples 1, 4, 5, and 6, and the suspension rate of Example 4 was the highest. This indicates that the preferred auxiliary agents play a key role in product quality.

FIELD TESTING

[062] This experiment was arranged in the greenhouse of Shandong Weifang Rainbow Chemical Co., Ltd., Weifang City, Shandong Province. The 50% terbuthylazine suspension concentrate, the 40% pyroxasulfone suspension concentrate, and the commercially available pesticide combination of Example 4 and Comparative Example 1 of the present disclosure were selected and mixed into formulations at the experimental design mass concentration after conversion according to the field area and the pot area. The pesticide application rate was expressed as g a.i/hm2, and clear water was used as a control. Plump and consistently sized Japanese brome grass seeds with broadleaf weed and Portulaca oteracea seeds with broadleaf weed were sown to 20 seeds, respectively, and then covered evenly. After treatment, they were grown in a greenhouse with each treatment in triplicate. The base of the pot was irrigated to make the soil completely moist, and the formulation was applied after seedling emergence.

[063] After application, symptoms of damage to Japanese brome grass and Portulaca oteracea were regularly observed. The number of plants remaining and the fresh weight above ground of Japanese brome grass and Portulaca oteracea from each treatment were counted 21 days after treatment. The plant control effect and fresh weight control effect of each treatment were calculated according to the following formulas.

[064] Plant control effect (%) = (the number of weeds in the control group - the number of weeds in the treatment group) / the number of weeds in the control group x 100%;

[065] Fresh weight control effect (%) = (fresh weight of weeds in the control group - fresh weight of weeds in the treatment group) / fresh weight of weeds in the control group x 100%.

[066] The results shown show that the combination of active components in the pesticide composition provided by the present disclosure reduces the rate of herbicide application and, thus, reduces the cost of the formulations. Additionally, through the selection and optimization of the combination of auxiliary agents, such as a wetting agent and an anti-freezing agent, the problem of product peeling is solved, and the stability of the product is improved.

[067] The descriptions of the exposed modalities are used only to help understand the method and central idea of the present disclosure. It should be pointed out that, by those skilled in the art, various improvements and modifications can also be made to the present disclosure without departing from the principle of the present disclosure, and these improvements and modifications also fall within the scope of protection of the claims of the present disclosure. Table 1 Ratio of each raw material in Examples 1~4 Table 2 Ratio of each raw material in Examples 5 to 7 and Comparative Example 1 Petition 870220056750, of 06/29/2022, p. 27/37 Table 3 Performance of aqueous suspension concentrates prepared by the composition of terbuthylazine and pyroxasulfone Table 4 Efficacy test data Table 5 Record table of raw efficacy data

Claims (13)

1. Suspension concentrate containing terbuthylazine and pyroxasulfone, characterized by comprising, in mass content: 40%~60% of an active ingredient, 4%~10% of a dispersant, 1%~5% of a wetting agent, 0 .1%~4% of a thickener, and 0.2%~3% of an antifoam agent; wherein the active ingredient comprises terbuthylazine and pyroxasulfone. 2. Suspension concentrate containing terbuthylazine and pyroxasulfone according to claim 1, characterized in that it additionally comprises an anti-freezing agent and/or a preservative. 3. Suspension concentrate containing terbuthylazine and pyroxasulfone according to claim 2, characterized in that it comprises, in mass content: 40%~60% of an active ingredient, 4%~10% of a dispersant, 1%~5% of a wetting agent, 0.1%~4% of a thickener, 0.2%~3% of an antifoam agent, 3%~10% of an antifreeze agent, 0.1%~2% of a preservative, and deionized water supplementing up to 100%; wherein the active ingredient comprises terbuthylazine and pyroxasulfone. 4. Suspension concentrate containing terbuthylazine and pyroxasulfone according to claim 1, characterized in that the dispersant is selected from the group consisting of lignosulfonate, triethanolamine salt of tristyrylphenol polyoxyethylene ether phosphate, styrene-acrylic acid copolymer, sodium salt of the copolymer in styrene and maleic anhydride, condensed alkylnaphthalene sulfonate - formaldehyde, ammonium salt of tristyrylphenol polyoxyethylene ether sulfate, methyl methacrylate copolyoxyethylene ether, and a mixture thereof. 5. Suspension concentrate containing terbuthylazine and pyroxasulfone according to claim 4, characterized in that the dispersant comprises a first dispersant and a second dispersant; the first dispersant being selected from the group consisting of lignosulfonate, triethanolamine salt of tristyrylphenol polyoxyethylene ether phosphate, and ammonium salt of tristyrylphenol polyoxyethylene ether sulfate, and the second dispersant being selected from the group consisting of styrene copolymer - acrylic acid, condensed alkylnaphthalene sulfonate - formaldehyde, and methyl methacrylate copolyoxyethylene ether. 6. Suspension concentrate containing terbuthylazine and pyroxasulfone according to claim 5, characterized in that a mass ratio of the first dispersant to the second dispersant is preferably (1~2):1. 7. Suspension concentrate containing terbuthylazine and pyroxasulfone according to claim 1, characterized in that the wetting agent is selected from the group consisting of polyether block of propylene oxide-ethylene oxide, fatty alcohol of polyoxyethylene ether, alcohol of polyoxyethylene polyoxypropylene fatty ether, polyoxyethylene ether fatty lauryl alcohol, and a mixture thereof. 8. Suspension concentrate containing terbuthylazine and pyroxasulfone according to claim 7, characterized in that the wetting agent is selected from propylene oxide-ethylene oxide block polyether and polyoxyethylene ether fatty alcohol. 9. Suspension concentrate containing terbuthylazine and pyroxasulfone according to claim 1, characterized in that the thickener is selected from the group consisting of magnesium and aluminum silicate, organic bentonite, xanthan gum, ordinary white carbon black, and a mixture thereof; and the antifoam agent is selected from the group consisting of polyether antifoam agent, organosilicon antifoam agent, polyether modified polysiloxane antifoam agent, and a mixture thereof. 10. Suspension concentrate containing terbuthylazine and pyroxasulfone according to claim 9, characterized in that the thickener is selected from ordinary white carbon black and xanthan gum; and the antifoam agent is selected from polyether antifoam agent and organosilicon antifoam agent. 11. Suspension concentrate containing terbuthylazine and pyroxasulfone according to claim 2, characterized in that the antifreeze agent is selected from the group consisting of urea, ethylene glycol, propylene glycol, glycerol, and a mixture thereof; and the preservative being selected from the group consisting of Kathon, paraformaldehyde, sodium benzoate, and a mixture thereof. 12. Suspension concentrate containing terbuthylazine and pyroxasulfone according to claim 11, characterized in that: the antifreeze agent is selected from ethylene glycol and glycerol; and the preservative will be Kathon. 13. Method of preparing the suspension concentrate containing terbuthylazine and pyroxasulfone as defined in any one of claims 1 to 12, characterized in that it comprises the steps of: mixing a wetting agent, a dispersant, a preservative, an antifoam agent, an antifreeze agent and water evenly, then add thickener and active ingredients under high speed shear condition, mix evenly and grind to obtain suspension concentrate containing terbuthylazine and pyroxasulfone.