Water emulsion-suspension type pretilachlor herbicide as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of pesticide herbicides, and discloses an emulsion-suspension type pretilachlor herbicide which is obtained by uniformly mixing and dispersing pretilachlor emulsion in water and pretilachlor sustained-release agent microparticles according to the mass ratio of (4-40): 1. The dosage form not only contains an o / w type aqueous emulsion, but also contains suspended slow-release pretilachlor microparticles, has good dispersity and slow-release property, has a good weeding effect, is safe and environment-friendly, and has the effect of promoting the growth of rice. Different from the existing commonly used missible oil preparation, the pretilachlor herbicide provided by the invention avoids the use of irritant and toxic organic solvents, improves the production and application safety of pretilachlor herbicides, and protects human health and ecological environment. The invention further discloses a preparation method and application, application is more convenient, the effect is better, and the water emulsion-suspended pretilachlor herbicide has the advantages of being fast in early-stage release and slow in later-stage release and is beneficial for improving the weeding effect.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticide herbicides, and particularly relates to an eco-friendly pretilachlor aqueous emulsion-suspension concentrate containing no toxic organic solvents, and a preparation method and application thereof. Background Art

[0002] Pretilachlor is an oily liquid and a highly selective herbicide for rice fields. It cannot be dispersed in water and its solubility in water at 20°C is 50 mg / L. It needs to be processed into a convenient dosage form before it can be used. At present, the main dosage forms of pretilachlor herbicides include emulsifiable concentrates, water emulsions, wettable powders, granules, etc. Among them, emulsifiable concentrates and water emulsions are fluid, have low preparation costs, and are simple and convenient to use, so they have been widely promoted and applied. However, these two dosage forms still have some shortcomings: 1. The disadvantage of existing emulsifiable concentrate products is that, generally, pungent and toxic organic solvents are added to pretilachlor, such as one or more toluene, xylene, acetone, kerosene, cyclohexane, cyclohexanone, etc. These toxic organic solvents not only affect the production safety of the product, but also the emulsifiable concentrate products harm the growth of rice, damage human health, and seriously pollute the ecological environment.

[0003] 2. The shortcomings of existing water-emulsion products are that, first, toxic organic solvents such as toluene are generally added to pretilachlor as the oil phase, and then surfactants are used to emulsify it into an o / w type water emulsion, in which the harmfulness of the organic solvent is the same as that of the existing emulsifiable concentrate formulation; there are also water emulsions without adding toxic organic solvents, which have a single functional design and no sustained release effect. Second, in order to prevent low-temperature freezing, existing water emulsions add ethylene glycol or polyethylene glycol as antifreeze aids, which will poison rice or inhibit rice growth and reduce yield; third, existing water emulsion technology still needs to improve the application effect research. In fact, the application effect of a herbicide should reflect the weed control rate and focus on its degree of damage to crops. The present invention found that although some water emulsion technologies have added rice safener 4,6-dichloro-2-phenylpyrimidine, it still affects rice growth.

[0004] Based on the current situation that emulsifiable concentrate or water-emulsion formulation is single and the application effect needs to be improved, it is urgent to invent a water-emulsion-suspension formulation of pretilachlor herbicide that does not contain toxic organic solvents and chemical substances that inhibit rice growth, so that it has the characteristics of safety, environmental protection and economy. This is the beneficial technical content for realizing "green agriculture" and "efficient agriculture" and is an important direction for the development of pesticide formulations. Summary of the invention The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a water-emulsion-suspension pretilachlor herbicide that does not contain toxic organic solvents and chemical substances that inhibit rice growth, which has good weed control effect, is safe, environmentally friendly and promotes rice growth.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is: A pretilachlor herbicide in the form of an emulsion-suspension formulation, which is obtained by uniformly mixing and dispersing a pretilachlor emulsion-in-water and pretilachlor slow-release agent microparticles in a mass ratio of 4-40:1; The raw materials of the pretilachlor emulsion in water include the following components in parts by weight: Pretilachlor: 5.0-55.0 parts by weight, 4,6-dichloro-2-phenylpyrimidine: 0.25-22.0 parts by weight, emulsifier: 3.24-42.0 parts by weight, polyethylene glycol stearate: 0.9-8.0 parts by weight, stearic acid monoglyceride: 0.3-3.0 parts by weight, diisobutylnaphthalene sulfonate: 0.2-4.5 parts by weight, penetrant T: 0.6-6.0 parts by weight, low molecular weight polyacrylate: 0.2-3.5 parts by weight, urea: 1.2-5.0 parts by weight, water: 50.0-100.0 parts by weight; The raw materials of the pretilachlor sustained-release microgranules include the following components in parts by weight: Pretilachlor: 10.0-80.0 parts by weight, kaolin: 9.0-116.0 parts by weight, microcrystalline cellulose: 1.5-8.0 parts by weight, acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer: 30.0-100.0 parts by weight, water: 15.0-80.0 parts by weight.

[0006] The above-mentioned water emulsion-suspension type pretilachlor herbicide, preferably, the raw materials of the pretilachlor water emulsion also include 3-12 parts of vegetable oil, and the vegetable oil includes any one or more of rapeseed oil, palm oil, soybean oil, corn oil, olive oil, tea seed oil, cottonseed oil and sunflower seed oil; the diisobutylnaphthalene sulfonate is sodium diisobutylnaphthalene sulfonate. The vegetable oil is non-toxic and harmless, has no irritating odor, and is used as a diluent solvent in the formula. Preferably, the vegetable oil is preferably rapeseed oil and soybean oil, etc. These vegetable oils have low freezing points and are beneficial to maintaining dispersibility at low temperatures.

[0007] Preferably, the emulsifier includes Tween 20: 2.7-30.0 parts by weight; Tween 60: 0.3-9.0 parts by weight; Span 20: 0.24-3.0 parts by weight; the low molecular weight polyacrylate is a low molecular weight polymer of sodium acrylate or potassium acrylate, with a pH of 6-8 and a number average molecular weight of 2000-10000.

[0008] Preferably, in the pretilachlor aqueous emulsion, the preferred amount of the pretilachlor is 20-40 parts by weight; the preferred amount of 4,6-dichloro-2-phenylpyrimidine is 3-12 parts by weight; Tween 20 is the main emulsifier, and the preferred amount is 5-20 parts by weight; Tween 60 and Span 20 are auxiliary emulsifiers, which can increase the stability of the emulsified system, and the preferred amounts are 0.9-4.5 parts by weight and 0.6-1.8 parts by weight, respectively; polyethylene glycol stearate and stearic acid monoglyceride can play a thickening and stabilizing role, and can increase the consistency and stability of the emulsified system, and the preferred amounts are 0.6-1.5 parts by weight, respectively and 0.5-1.5 weight parts; diisobutylnaphthalene sulfonate and penetrant T can play a strong diffusion and wetting role, significantly increase the dispersibility of the aqueous emulsion in water, and the preferred amounts are 1.2-3.5 weight parts and 1.5-4.0 weight parts respectively; low molecular weight polyacrylate plays the role of dispersing emulsion particles in the lubricating system, preferably potassium polyacrylate (containing potassium ions beneficial to plant growth) is used, and the amount is 0.4-1.8 weight parts; the preferred amount of vegetable oil is 3-9.0 weight parts; urea is used as an antifreeze agent, and the preferred amount is 2.0-4.0 weight parts; the preferred amount of water is 60-80 weight parts.

[0009] Preferably, the acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer is obtained by ternary copolymerization of three monomers of acrylic acid, hydroxypropyl acrylate and N-hydroxymethyl acrylamide in a molar ratio of (2-6):(1-5):(1-5).

[0010] In the described pretilachlor sustained-release agent granules, kaolin and microcrystalline cellulose are used as physical adsorption carrier materials for pretilachlor, and acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer is used as a water-soluble polymer material, which can be dried and dehydrated at 70-105°C to achieve self-crosslinking to form a network structure. Its role in the described pretilachlor sustained-release agent granules is to seal and fix pretilachlor to achieve a slow release effect.

[0011] Based on a general inventive concept, the present invention also provides a method for preparing a water emulsion-suspension type pretilachlor herbicide, comprising the following steps: (1) Preparing a pretilachlor emulsion in water: adding 4,6-dichloro-2-phenylpyrimidine, diisobutylnaphthalene sulfonate, stearic acid monoglyceride, polyethylene glycol stearate, and vegetable oil to pretilachlor and heating to dissolve, then adding low molecular weight polyacrylate, Tween 20, Tween 60, Span 20, penetrant T, and urea, and finally adding water, stirring and emulsifying to obtain the pretilachlor emulsion in water; (2) Preparing pretilachlor sustained-release microparticles: stirring and dispersing acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer, water, kaolin and microcrystalline cellulose, and finally adding pretilachlor and stirring and mixing to form a viscous paste. The paste is dried and crushed into powder to obtain the pretilachlor sustained-release microparticles; (3) The pretilachlor emulsion in water and the pretilachlor sustained-release agent microparticles are mixed and dispersed uniformly to obtain the pretilachlor herbicide in the form of an emulsion-suspension formulation.

[0012] In the above preparation method, preferably, in step (1), the heating temperature is 50-90° C., and the stirring and emulsification is carried out by uniform stirring at a shear emulsifier speed of 100-10000 r / min.

[0013] Preferably, in step (2), the preparation method of the acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer is as follows: S1, neutralizing acrylic acid with sodium hydroxide to a pH of 6-7 to obtain neutral acrylic acid; S2, adding sodium hypophosphite to the aqueous solution, wherein the mass concentration of sodium hypophosphite in the aqueous solution is 0.4-2.0%; S3, adding three monomers of neutral acrylic acid, hydroxypropyl acrylate and N-hydroxymethyl acrylamide to the aqueous solution after step S2, with the molar ratio of the three monomers being 2-6:1-5:1-5, and the total mass concentration of the three monomers in the aqueous solution being 10-30%, to obtain a ternary copolymer system; S4, place the ternary copolymer system in 60 The polymerized product is irradiated in a Co γ-ray field with a radiation dose of 0.6-20.0 kGy and a dose rate of 0.3-12.0 kGy / h to obtain an acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer.

[0014] Preferably, in step (2), the drying is performed by hot air drying at 70-105°C (preferably 95°C), and the powder is a powder with a mesh size of 300 or more.

[0015] Based on a general inventive concept, the present invention also provides an application of an aqueous emulsion-suspension type pretilachlor herbicide, wherein the aqueous emulsion-suspension type pretilachlor herbicide is used for weeding in direct-seeded rice fields, with a net content of pretilachlor of 45-75 g / mu.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The aqueous emulsion-suspension type pretilachlor herbicide of the present invention contains both an o / w aqueous emulsion and suspended slow-release pretilachlor microparticles, has good dispersibility and slow-release properties, has good weed control effects, is safe and environmentally friendly, and can promote rice growth.

[0017] 2. Different from the commonly used emulsifiable concentrates, the present invention avoids the use of irritating and toxic organic solvents, improves the production and application safety of pretilachlor herbicides, and protects human health and the ecological environment; 3. Different from the existing water emulsion, the pretilachlor sustained-release particles contained in the water emulsion-suspension pretilachlor herbicide of the present invention have a sustained-release effect. Therefore, it not only has a good weed control effect, but also does not cause rice damage, and is particularly beneficial to rice growth.

[0018] 4. Unlike the pretilachlor granules which need to be mixed with soil or mixed with other matrix carriers for spreading, the pretilachlor herbicide of the present invention can be used by diluting and dispersing with water, which is more convenient to use and has better effect. The pretilachlor herbicide of the present invention has the characteristics of fast release in the early stage and slow release in the later stage, which is beneficial to improving the weed control effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The figures are the weed control effect and rice growth in the laboratory (21st day and 30th day), from left to right: clean water, pretilachlor emulsifiable concentrate (commercially available), and the aqueous emulsion-suspension pretilachlor herbicide of the present invention; Figure 2 It is a real picture of weed control effect and rice growth, wherein: A, clean water; B, pretilachlor emulsifiable concentrate (commercially available); C, pretilachlor water emulsion prepared by the present invention; D, pretilachlor water emulsion-suspension type herbicide prepared by the present invention; Figure 3 The release curves of the pretilachlor emulsifiable concentrate (commercially available), the pretilachlor aqueous emulsion prepared by the present invention, and the pretilachlor herbicide in aqueous emulsion-suspension form prepared by the present invention; DETAILED DESCRIPTION In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0021] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0022] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0023] The acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer of the present invention is obtained by ternary copolymerization of acrylic acid, hydroxypropyl acrylate and N-hydroxymethyl acrylamide at a molar ratio of 3:1:1. The specific preparation method is as follows: ternary copolymerization of acrylic acid, hydroxypropyl acrylate and N-hydroxymethyl acrylamide is carried out, n acrylic acid: n hydroxypropyl acrylate: n N-hydroxymethyl acrylamide (molar ratio) = 3:1:1, and the total mass concentration of the three monomers in the aqueous solution is 30%, wherein the acrylic acid is neutralized with sodium hydroxide to a pH of 6-7, sodium hypophosphite is added to the aqueous solution (the mass concentration of sodium hypophosphite in the aqueous solution is 0.8%), and the ternary copolymer system is placed in 60 The polymer was polymerized by radiation in a Co γ-ray field with a radiation dose of 4 kGy and a dose rate of 0.8 kGy / h to obtain an acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer.

[0024] Embodiment 1-5: A pretilachlor herbicide in the form of an emulsion-suspension formulation is obtained by uniformly mixing and dispersing a pretilachlor emulsion-in-water (first component) and pretilachlor sustained-release microparticles (second component). The specific preparation method is as follows: (1) Preparation of pretilachlor emulsion in water: 4,6-dichloro-2-phenylpyrimidine, sodium diisobutylnaphthalene sulfonate, stearic acid monoglyceride, polyethylene glycol stearate, and edible vegetable oil are added (in no order) to pretilachlor and heated to (80°C) to dissolve, and then (in no order) low molecular weight polyacrylate, Tween 20, Tween 60, Span 20, penetrant T, and urea are added, and finally water is added, and the mixture is uniformly stirred and emulsified at a shear emulsifier speed of 1000 r / min to obtain the pretilachlor emulsion in water; the distribution ratio of each component in the pretilachlor emulsion in water is shown in Table 1; (2) Preparation of pretilachlor sustained-release microparticles: 100 parts by weight of acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer, 80 parts by weight of water, 116 parts by weight of kaolin and 8.0 parts by weight of microcrystalline cellulose were stirred and dispersed at room temperature, and finally 80 parts by weight of pretilachlor was added and stirred and mixed to form a viscous paste. The paste was dried at 95°C with hot air for 3 hours and then crushed into powder with a mesh size of 300 or more to obtain pretilachlor sustained-release microparticles; the net content of pretilachlor therein was determined to be 26.5% by liquid chromatography; (3) Add the slow-release pretilachlor granules into the mixture and stir to disperse the granules evenly to obtain a water-emulsion-suspension pretilachlor herbicide.

[0025] Table 1 Examples 1-5 (Formulation of water emulsion-suspension pretilachlor herbicide)

[0026] In order to verify the dispersibility of the aqueous emulsion-suspension pretilachlor herbicide of Example 1-5, the aqueous emulsion-suspension pretilachlor herbicide of Example 1-5 was diluted 300 times and placed in a conical glass bottle. The dispersibility after dilution at different times was shown in Table 2 under slight shaking of an oscillator (30 r / min). As can be seen from Table 2, the aqueous emulsion-suspension pretilachlor herbicide has good dispersibility after dilution and is convenient to use.

[0027] Table 2 Dispersibility of water emulsion-suspension pretilachlor herbicide

[0028] Description: No floating oil means that the water-insoluble substances (density is lower than water) in the water-emulsion-suspension pretilachlor herbicide dilution do not float on the surface of the dilution. No sinking oil and no precipitation means that the water-insoluble substances (density is higher than water) in the water-emulsion-suspension pretilachlor herbicide dilution and the pretilachlor slow-release agent particles do not settle to the bottom layer.

[0029] The aqueous emulsion-suspension pretilachlor herbicide of Example 3 was used as the research object to verify the sustained release property. The method was to add it into 100 ml of 30% methanol solution (net content of pretilachlor was 0.1600 g) and measure the release rate of pretilachlor. The same method was used to measure the release rate of pretilachlor emulsifiable concentrate (commercially available), pretilachlor aqueous emulsion (the first component of Example 3), and pretilachlor sustained release granules. Figure 3 It can be seen that at 60 minutes and 120 minutes, the content of pretilachlor emulsifiable concentrate (commercially available) was 90.9% and 96.4% respectively, the pretilachlor sustained-release agent granules (second component) had the best sustained-release performance, which were 31.5% and 37.7% respectively, and the aqueous emulsion-suspension type pretilachlor herbicide had sustained-release properties, and the pretilachlor release rates were 68.0% and 77.2% respectively. Data analysis and reasoning showed that the greater the content of the second component (pretilachlor sustained-release agent granules) in the aqueous emulsion-suspension pretilachlor herbicide, the better the pretilachlor sustained-release performance. The aqueous emulsion-suspension pretilachlor herbicide of the present invention has the characteristics of fast early release and slow late release, which is beneficial to prolonging the efficacy time and improving the weed control effect.

[0030] Embodiment 6: The invention discloses an application of a pretilachlor herbicide in an emulsion-suspension form, wherein the pretilachlor herbicide in an emulsion-suspension form is used for weeding in direct-seeded rice fields, and the net content of pretilachlor per mu is 45-75 g / mu.

[0031] 1. Laboratory weed control effect and rice growth (as shown in Table 3 and Figure 2 ) The present invention compares the weed control effect and rice growth of the commercial pretilachlor emulsifiable concentrate and the water emulsion-suspension pretilachlor herbicide of the present invention. Experimental method: add soil of the same mass and quality to the same container, plant the same number of rice seeds that have been germinated and whitened and barnyard grass seeds that have been soaked for 10 hours into the soil surface layer in the container, then add clean water or herbicide, and then add water to the container in equal amounts each time to moisten the soil according to the dryness and wetness of the soil, ensure that the seed growth conditions are the same, and observe the growth of rice and barnyard grass. The clean water sample means that no herbicide is added, and the net weight amount of the herbicide pretilachlor in other samples is 45g / mu.

[0032] Barnyard grass weed control rate (characterizing the weed control effect): η1=[(total barnyard grass number - surviving barnyard grass number) / total barnyard grass number]*100%; Rice survival rate (characterizing damage to rice): η2 = [(total number of rice - number of surviving barnyard grass) / total number of barnyard grass] * 100%; Rice plant height and rice growth morphology reflect whether herbicides are beneficial to rice growth.

[0033] Table 3 Laboratory weed control effect and rice growth

[0034] Experimental data show that the aqueous emulsion-suspension pretilachlor herbicide (the formulation of Example 3 of the present invention) is superior to the commercial pretilachlor emulsifiable concentrate, has a better weed control effect, does not harm rice and is beneficial to rice growth.

[0035] 2. Field weeding effect and rice growth Twelve independent plots of 6m×4m were built in the rice field. The same amount of rice seeds (Tianyou Huazhan) that had been germinated and whitened and barnyard grass seeds that had been soaked for 10 hours were evenly sown in each independent plot (100g rice seeds and 20g barnyard grass seeds per plot), and then different types of pretilachlor herbicides were sprayed (the net weight of pretilachlor in the pretilachlor emulsion and pretilachlor slow-release agent was 45g / mu). The experiment was designed with four samples, and each sample was repeated three times. The average value of the survey results is shown in Table 4 and Figure 3 .

[0036] Table 4 Rice growth in the field

[0037] From the field experiment results in Table 4 and Figure 3It can be seen that the order of growth advantage of field rice judging from the overall appearance is the pretilachlor emulsion-suspension herbicide prepared by the present invention> the pretilachlor emulsion prepared by the present invention> water> emulsifiable concentrate (commercially available), and the plant height, root length and main stem width of rice using the pretilachlor emulsion-suspension herbicide prepared by the present invention are significantly better than those of the emulsifiable concentrate (commercially available). This shows that the pretilachlor emulsion-suspension herbicide of the present invention has a good weed control effect, is safe and environmentally friendly, and promotes rice growth.

Claims

1. A pretilachlor herbicide in the form of an emulsion-suspension formulation, characterized in that: The method is obtained by uniformly mixing and dispersing the pretilachlor aqueous emulsion and the pretilachlor sustained-release agent microparticles in a mass ratio of 4-40:1; The raw materials of the pretilachlor emulsion in water include the following components in parts by weight: Pretilachlor: 5.0-55.0 parts by weight, 4,6-dichloro-2-phenylpyrimidine: 0.25-22.0 parts by weight, emulsifier: 3.24-42.0 parts by weight, polyethylene glycol stearate: 0.9-8.0 parts by weight, stearic acid monoglyceride: 0.3-3.0 parts by weight, diisobutylnaphthalene sulfonate: 0.2-4.5 parts by weight, penetrant T: 0.6-6.0 parts by weight, low molecular weight polyacrylate: 0.2-3.5 parts by weight, urea: 1.2-5.0 parts by weight, water: 50.0-100.0 parts by weight; The raw materials of the pretilachlor sustained-release microgranules include the following components in parts by weight: Pretilachlor: 10.0-80.0 parts by weight, kaolin: 9.0-116.0 parts by weight, microcrystalline cellulose: 1.5-8.0 parts by weight, acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer: 30.0-100.0 parts by weight, water: 15.0-80.0 parts by weight.

2. The aqueous emulsion-suspension type pretilachlor herbicide according to claim 1, characterized in that: The raw materials of the pretilachlor aqueous emulsion also include 3-12 parts of vegetable oil, and the vegetable oil includes any one or more of rapeseed oil, palm oil, soybean oil, corn oil, olive oil, tea seed oil, cottonseed oil and sunflower seed oil; the diisobutylnaphthalene sulfonate is sodium diisobutylnaphthalene sulfonate.

3. The aqueous emulsion-suspension type pretilachlor herbicide according to claim 1, characterized in that: The emulsifier includes Tween 20: 2.7-30.0 weight parts; Tween 60: 0.3-9.0 weight parts; Span 20: 0.24-3.0 weight parts; the low molecular weight polyacrylate is a low molecular weight polymer of sodium acrylate or potassium acrylate, with a pH of 6-8 and a number average molecular weight of 2000-10000.

4. The aqueous emulsion-suspension type pretilachlor herbicide according to claim 1, characterized in that: The raw materials of the pretilachlor emulsion in water include the following components in parts by weight: Pretilachlor: 20.0-40.0 parts by weight, 4,6-dichloro-2-phenylpyrimidine: 3.0-12.0 parts by weight, Tween 20: 5.0-20.0 parts by weight; Tween 60: 0.9-4.5 parts by weight; Span 20: 0.6-1.8 parts by weight, polyethylene glycol stearate: 0.6-1.5 parts by weight, stearic acid monoglyceride: 0.5-1.5 parts by weight, diisobutylnaphthalene sulfonate: 1.2-3.5 parts by weight, penetrant T: 1.5-4.0 parts by weight, low molecular weight polyacrylate: 0.4-1.8 parts by weight, vegetable oil: 3.0-9.0 parts by weight, urea: 2.0-4.0 parts by weight, water: 60.0-80.0 parts by weight.

5. The aqueous emulsion-suspension type pretilachlor herbicide according to any one of claims 1 to 4, characterized in that: The acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer is obtained by ternary copolymerization of three monomers of acrylic acid, hydroxypropyl acrylate and N-hydroxymethyl acrylamide at a molar ratio of (2-6):(1-5):(1-5).

6. A method for preparing the aqueous emulsion-suspension type pretilachlor herbicide according to any one of claims 1 to 4, characterized in that: The steps include: (1) Preparing a pretilachlor emulsion in water: adding 4,6-dichloro-2-phenylpyrimidine, diisobutylnaphthalene sulfonate, stearic acid monoglyceride, polyethylene glycol stearate, and vegetable oil to pretilachlor and heating to dissolve, then adding low molecular weight polyacrylate, Tween 20, Tween 60, Span 20, penetrant T, and urea, and finally adding water, stirring and emulsifying to obtain the pretilachlor emulsion in water; (2) Preparing pretilachlor sustained-release microparticles: stirring and dispersing acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer, water, kaolin and microcrystalline cellulose, and finally adding pretilachlor and stirring and mixing to form a viscous paste. The paste is dried and crushed into powder to obtain the pretilachlor sustained-release microparticles; (3) The pretilachlor emulsion in water and the pretilachlor sustained-release agent microparticles are mixed and dispersed uniformly to obtain the pretilachlor herbicide in the form of an emulsion-suspension formulation.

7. The method for preparing the aqueous emulsion-suspension type pretilachlor herbicide according to claim 6, characterized in that: In step (1), the heating temperature is 50-90° C., and the stirring emulsification is carried out by uniform stirring at a shear emulsifier speed of 100-10000 r / min.

8. The method for preparing the aqueous emulsion-suspension type pretilachlor herbicide according to claim 6, characterized in that: In step (2), the preparation method of the acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer is as follows: S1, neutralizing acrylic acid with sodium hydroxide to a pH of 6-7 to obtain neutral acrylic acid; S2, adding sodium hypophosphite to the aqueous solution, wherein the mass concentration of sodium hypophosphite in the aqueous solution is 0.4-2.0%; S3, adding three monomers of neutral acrylic acid, hydroxypropyl acrylate and N-hydroxymethyl acrylamide to the aqueous solution after step S2, with the molar ratio of the three monomers being 2-6:1-5:1-5, and the total mass concentration of the three monomers in the aqueous solution being 10-30%, to obtain a ternary copolymer system; S4, place the ternary copolymer system in 60 The polymerized product is irradiated in a Co γ-ray field with a radiation dose of 0.6-20.0 kGy and a dose rate of 0.3-12.0 kGy / h to obtain an acrylic acid-hydroxypropyl acrylate-N-hydroxymethyl acrylamide copolymer.

9. The method for preparing the aqueous emulsion-suspension type pretilachlor herbicide according to claim 6, characterized in that: In step (2), the drying is performed by hot air drying at 70-105° C., and the powder is a powder with a mesh size of 300 or more.

10. Use of the pretilachlor herbicide in an emulsion-suspension formulation according to any one of claims 1 to 5 or the pretilachlor herbicide obtained by the preparation method according to any one of claims 6 to 9, characterized in that: The aqueous emulsion-suspension type pretilachlor herbicide is used for weeding in direct-seeded rice fields, with a net content of pretilachlor of 45-75 g / mu.

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