Diuron granule and production process thereof

Abstract

The invention discloses diuron granules and a production process thereof, and relates to the technical field of pesticides, and the production process comprises the following steps: uniformly mixing diuron and a porous starch carrier, then adding a dispersing agent and a wetting agent, uniformly mixing, and then carrying out crushing treatment through an ultramicro jet mill to obtain granules; placing the granules in a fluidized bed granulator, then spraying an adhesive, and granulating to form master batches; the surfaces of the master batches are sequentially coated with a controlled release film containing ethyl cellulose and nano titanium dioxide and an anti-caking film containing polylactic acid and diatomite microspheres through a fluidized bed, and granules are obtained; performing size grading on the granules by adopting a three-dimensional screening device, performing microwave-hot air coupling drying, and finally performing nitrogen-filled packaging after electrostatic adsorption dust removal to obtain the diuron granules. The diuron granule has higher drug loading property, compressive strength and longer validity period.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticides, and in particular to a diuron granule and a production process thereof. Background Art

[0002] Diuron, as a broad-spectrum urea herbicide, is widely used for non-selective weed control in crops such as sugarcane and cotton.

[0003] During the granulation process of traditional diuron formulations (such as wettable powders and suspension concentrates), the physical mixing of diuron technical with carriers (such as diatomaceous earth and bentonite) easily generates micron-sized dust, which not only causes loss of the active ingredient but also poses a serious health hazard to operators. Furthermore, conventional carriers have a low specific surface area, with drug loading rates generally below 50%, resulting in increased drug usage per unit area and increasing the environmental burden.

[0004] At the same time, existing granules mostly use single-layer coating technology, such as the ethyl cellulose coating disclosed in the patent document with publication number EP2868155B1. Its release behavior is significantly affected by environmental factors. For example, when the soil moisture is greater than 70% during the rainy season, the drug burst release rate is as high as 23.5%, resulting in the risk of drug damage. Under drought conditions, the coating film degrades slowly, and the effective period is only 60-80 days, requiring multiple reapplications, which increases labor costs.

[0005] To solve the above problems, the existing technology has proposed improvement measures. For example, the patent document with publication number CN105175433A proposes using mesoporous silica as a carrier. Although the drug loading rate is increased to 65%, the surface silanol group and the diuron molecules undergo irreversible adsorption, resulting in an actual release rate of only 42%-48%; the patent document with publication number CN107698770A uses pH-responsive polymer coating, but the soil pH fluctuation range is small, the controlled release effect is limited, and the field persistence period is only extended by 15 days. Summary of the Invention

[0006] The purpose of the present invention is to provide a diuron granule and a production process thereof to solve the following technical problems:

[0007] How to improve the drug loading effect and duration of diuron granules.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A production process of diuron granules comprises the following steps:

[0010] Step 1: Diuron and a porous starch carrier are mixed evenly in a weight ratio of 1: (3-5), and then a dispersant and a wetting agent are added and mixed evenly, and then crushed by an ultrafine airflow mill at an airflow pressure of 0.8-1.2 MPa (preferably 1.0 MPa) for 30-45 minutes (preferably 40 minutes) to obtain a granule with a particle size D90 ≤ 10 μm and a specific surface area of ≥ 150 m 2 / g;

[0011] Step 2: placing the granules in a fluidized bed granulator, and then spraying the binder for granulation. During the granulation process, the inlet air temperature of the fluidized bed granulator is 45-55°C (preferably 50°C), the atomization pressure is 0.15-0.25MPa (preferably 0.2MPa), the spray rate is 10-15mL / min (preferably 12mL / min), and the granulation time is 20-30min (preferably 25min), and finally a masterbatch with a particle size of 0.8-1.2mm is formed;

[0012] Step 3: coating the surface of the masterbatch with a controlled release membrane containing ethyl cellulose and nano-titanium dioxide and an anti-caking membrane containing polylactic acid and diatomaceous earth microspheres in a fluidized bed in sequence to obtain granules;

[0013] Step 4: Use a three-dimensional screening device with a vibration frequency of 20-30 Hz (preferably 25 Hz) and a mesh aperture of 0.7-1.5 mm (preferably 1 mm) to size classify the granules, thereby removing particles with unqualified particle size, and then enter a microwave-hot air coupled drying system with a microwave frequency of 2450 MHz, a power density of 0.5-1.0 W / g (preferably 0.8 W / g), a hot air temperature of 60-80°C (preferably 70°C), and a wind speed of 1.2-1.5 m / s (preferably 1.3 m / s) until the moisture content is ≤0.5%. Finally, after electrostatic adsorption dust removal by a high-voltage electrostatic precipitator of 30-50 kV (preferably 40 kV), the granules are sealed and packaged in a nitrogen atmosphere with an oxygen content of ≤0.5% to obtain diuron granules.

[0014] Furthermore, in step 1, the porous starch carrier is prepared by the following method:

[0015] Step A1: corn starch with a purity of ≥98% and α-amylase with an enzyme activity of 5000 U / g are enzymatically hydrolyzed in a phosphate buffer with a pH of 6.0 at 55-60° C. (preferably 58° C.) with stirring for 30 minutes, and then rapidly heated to 90° C. to inactivate the enzyme for 10 minutes;

[0016] Step A2, placing the enzymatically hydrolyzed corn starch in a supercritical reactor, introducing CO2 gas, controlling the pressure at 15 MPa and the temperature at 45°C, maintaining for 2 hours, then releasing the pressure at a rate of 5 MPa / min, and then drying in a vacuum drying oven at 50°C and -0.09 MPa to a moisture content of ≤3%;

[0017] Step A3: Place the dried starch in a turbine mill and grind it to a particle size of D50 = 20-30 μm at a speed of 8000-10000 rpm (preferably 9000 rpm). The porous starch carrier is collected through a 200-mesh sieve. The specific surface area of the porous starch carrier is ≥ 250 m 2 / g, and the pore size distribution is 2-50nm.

[0018] Furthermore, in step 1, the dispersant is a polycarboxylate, preferably sodium polyacrylate with a molecular weight of 2000-5000 Da; the weight ratio of the polycarboxylate to diuron is 100:(2-5), preferably 100:3.

[0019] Furthermore, in step 1, the wetting agent is an alkylnaphthalene sulfonate, preferably sodium dodecylnaphthalene sulfonate; the weight ratio of the alkylnaphthalene sulfonate to diuron is 100:(1-3), preferably 100:2.

[0020] Furthermore, in step 2, the binder is composed of cross-linked sodium carboxymethyl cellulose, polyvinyl butyral ester and modified attapulgite clay in a weight ratio of 100:35:(0.1-0.3), and the weight ratio of the three is preferably 100:35:0.2; wherein the modified attapulgite clay is prepared by the following method: natural attapulgite clay is crushed to 200 mesh, calcined at 500°C for 2h, and then the calcined natural attapulgite clay is mixed with hexadecyltrimethylammonium bromide (CTAB) at a weight ratio of 1:0.5, stirred at 70°C in an alkaline solution of pH 9.0 for 4h, and centrifuged and washed until there is no Br - The residue was then vacuum dried at 80 °C for 6 h to obtain modified attapulgite clay.

[0021] Furthermore, in step three, the controlled release membrane accounts for 3-5 wt% of the masterbatch mass, preferably 4 wt%;

[0022] Furthermore, the controlled release membrane comprises the following components in parts by weight: 40-50 parts of ethyl cellulose, 5-8 parts of nano titanium dioxide, 2-3 parts of triethyl citrate, and 1-2 parts of glyceryl monostearate;

[0023] Preferably, ethyl cellulose is 45 parts, nano titanium dioxide is 6 parts, triethyl citrate is 2.5 parts, and glyceryl monostearate is 1.5 parts.

[0024] Furthermore, the controlled release membrane coating method is: dissolving the components of the controlled release membrane in anhydrous ethanol in proportion to form an inner coating liquid with a solid content of 12-15% (preferably 13%), and then mixing and coating the inner coating liquid with the masterbatch in a pulsed fluidized bed to obtain a masterbatch coated with the controlled release membrane.

[0025] Furthermore, the nano titanium dioxide is composed of anatase titanium dioxide and rutile titanium dioxide in a weight ratio of 7:3.

[0026] Furthermore, in step three, the anti-caking film accounts for 8-12 wt %, preferably 10 wt %, of the masterbatch.

[0027] Furthermore, the anti-caking film comprises the following components in parts by weight: 30-40 parts of polylactic acid, 10-15 parts of diatomaceous earth microspheres, 2-4 parts of magnesium stearate, and 1-3 parts of fumed silica;

[0028] Preferably, the polylactic acid is 35 parts, the diatomaceous earth microspheres are 12 parts, the magnesium stearate is 3 parts, and the fumed silica is 2 parts.

[0029] Furthermore, the coating method of the anti-caking film is: dissolving the components of the anti-caking film in ethyl acetate in proportion to form an outer coating liquid with a solid content of 8-10% (preferably 9%), and then mixing and coating the outer coating liquid with the masterbatch coated with the controlled release membrane in a pulsed fluidized bed to obtain the masterbatch coated with the anti-caking film.

[0030] Furthermore, in the pulsed fluidized bed of the inner coating liquid and the outer coating liquid, the pulse frequency is 5-8 Hz, the pulse waveform is a square wave, the duty cycle is 30-50%, the adsorption pressure is -(0.02-0.05) MPa, the single adsorption time is 3-5 s, the interval time is 2-3 s, the fluidizing gas velocity is 0.4-0.6 m / s, the air flow temperature is 40-50° C., a dual-fluid atomizing spray gun is used, the atomizing air pressure is 0.3-0.4 MPa, and the spray droplet particle size D50 is 50-80 μm;

[0031] Preferably, the pulse frequency is 7 Hz, the pulse waveform is a square wave, the duty cycle is 40%, the adsorption pressure is -0.04 MPa, the single adsorption time is 4 s, the interval time is 2.5 s, the fluidizing gas velocity is 0.5 m / s, the air flow temperature is 45 ° C, a dual-fluid atomizing spray gun is used, the atomizing air pressure is 0.35 MPa, and the spray droplet particle size D50 = 65 um.

[0032] Based on this, a preferred production process of diuron granules is obtained, comprising the following steps:

[0033] Step 1: Diuron and a porous starch carrier are mixed uniformly in a weight ratio of 1:4, and then sodium polyacrylate and sodium dodecylnaphthalene sulfonate with a molecular weight of 2000-5000Da are added and mixed uniformly, wherein the weight ratio of sodium polyacrylate to diuron is 100:3, and the weight ratio of sodium dodecylnaphthalene sulfonate to diuron is 100:2; and then crushed by an ultrafine airflow mill at an airflow pressure of 1MPa for 40min to obtain pellets with a particle size D90≤10um and a specific surface area of the pellets ≥150m 2 / g;

[0034] Step 2: Place the pellets in a fluidized bed granulator, and then spray the binder for granulation. During the granulation process, the inlet air temperature of the fluidized bed granulator is 50°C, the atomization pressure is 0.2MPa, the spray rate is 12mL / min, and the granulation time is 25min, ultimately forming a masterbatch with a particle size of 0.8-1.2mm;

[0035] Step 3: 45 parts of ethyl cellulose, 6 parts of nano titanium dioxide (composed of anatase titanium dioxide and rutile titanium dioxide in a weight ratio of 7:3), 2.5 parts of triethyl citrate, and 1.5 parts of glycerol monostearate were dissolved in anhydrous ethanol to form an inner coating liquid with a solid content of 13%; 35 parts of polylactic acid, 12 parts of diatomaceous earth microspheres, 3 parts of magnesium stearate, and 2 parts of fumed silica were dissolved in ethyl acetate to form an outer coating liquid with a solid content of 9%; the inner coating liquid was first mixed and coated with the masterbatch in a pulsed fluidized bed, and then the outer coating was The coating liquid is mixed with the masterbatch for coating in a pulsed fluidized bed. During the coating process, the inner coating liquid and the outer coating liquid have a pulse frequency of 7 Hz, a square wave pulse waveform, a duty cycle of 40%, an adsorption pressure of -0.04 MPa, a single adsorption time of 4 seconds, an interval time of 2.5 seconds, a fluidizing gas velocity of 0.5 m / s, an air flow temperature of 45°C, a dual-fluid atomizing spray gun, an atomizing air pressure of 0.35 MPa, and a spray droplet size D50 of 65 μm. Finally, a controlled-release film and an anti-caking film are sequentially coated on the surface of the masterbatch to obtain granules.

[0036] Step 4: Use a three-dimensional screening device with a vibration frequency of 25 Hz and a mesh aperture of 1 mm to size-classify the granules to remove particles with unqualified particle size, and then enter a microwave-hot air coupled drying system with a microwave frequency of 2450 MHz, a power density of 0.8 W / g, a hot air temperature of 70°C, and a wind speed of 1.3 m / s until the moisture content is ≤0.5%. Finally, after electrostatic adsorption dust removal by a 40 kV high-voltage electrostatic precipitator, the granules are sealed and packaged in a nitrogen atmosphere with an oxygen content of ≤0.5% to obtain diuron granules.

[0037] In a second aspect, the present invention further discloses a diuron granule, which is prepared by the production process of diuron granule as described above.

[0038] Beneficial effects of the present invention:

[0039] 1. A porous starch carrier is introduced into the diuron granules of the present invention. Through directional hydrolysis by α-amylase combined with supercritical CO2 pore expansion treatment, the specific surface area of the carrier is increased, the porosity is increased, and the drug loading limit of conventional carriers is broken through, thereby improving the drug loading rate.

[0040] 2. The binder in the diuron granules of the present invention introduces CTAB intercalated modified attapulgite clay, which increases the interlayer spacing. The surface hydroxyl groups form a hydrogen bond network with the diuron molecules, which greatly improves the compressive strength of the particles and shortens the granulation time.

[0041] 3. The coating of the diuron granules of the present invention adopts an inner and outer double-layer coating. The inner layer contains nano-titanium dioxide with anatase TiO2 (photocatalytic active site) and rutile TiO2 (ultraviolet shielding function) compounded in a ratio of 7:3. The membrane porosity can be dynamically adjusted under light conditions, so that the drug release rate is positively correlated with the field light intensity; the outer layer of diatomaceous earth microspheres acts as a physical barrier. When the soil moisture reaches a certain level, it absorbs water and expands to produce microcracks, which can achieve humidity-responsive release, thereby increasing its lasting effect. DETAILED DESCRIPTION

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] Unless otherwise specified, the experimental methods in the following preparations, examples, and comparative examples are conventional methods and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, can be obtained from commercial sources, for example:

[0044] Corn starch: purchased from Shandong Hengren Corn Starch Co., Ltd., purity ≥98;

[0045] α-Amylase: purchased from Shanghai Kanglang Biotechnology Co., Ltd., with an enzyme activity of 5000 U / g;

[0046] Natural attapulgite clay: purchased from Jiangsu Xuyi Attapulgite Clay Co., Ltd., purity ≥85 (the interlayer spacing of the original ore is 1.2 nm);

[0047] Ethyl cellulose: purchased from the official website www.ashland.com, viscosity 45-55 mPa·s;

[0048] Polylactic acid: purchased from Anhui Fengyuan Group Co., Ltd., molecular weight 80,000-120,000 Da;

[0049] Diatomaceous earth microspheres: purchased from Shanghai Naqian Chemical, particle size 5-10 μm;

[0050] Cross-linked sodium carboxymethyl cellulose: purchased from Shanxi Jinyang Pharmaceutical Excipients Co., Ltd., with a viscosity of 200-300 mPa·s;

[0051] Polyvinyl butyral: purchased from Shandong Ruifeng Polymer Materials Co., Ltd., with an alcoholysis degree of 88%-92%;

[0052] Sodium polyacrylate: purchased from Henan Zhengjia Energy and Environmental Protection Co., Ltd., with a molecular weight of 2000-5000 Da.

[0053] Preparation Example 1

[0054] Preparation of porous starch carrier:

[0055] Step 1: corn starch and α-amylase were enzymolyzed in a phosphate buffer solution with a pH of 6.0 at a weight ratio of 19:1 at 58°C for 30 minutes, and then the temperature was rapidly raised to 90°C for 10 minutes to inactivate the enzyme;

[0056] Step 2: Place the enzymatically hydrolyzed corn starch in a supercritical reactor, introduce CO2 gas, control the pressure to 15 MPa and the temperature to 45°C, maintain for 2 hours, then release the pressure at a rate of 5 MPa / min, and then dry in a vacuum drying oven at 50°C and -0.09 MPa to a moisture content of ≤3%;

[0057] Step 3: The dried starch was placed in a turbine grinder and ground at a speed of 9000 rpm to a particle size of D50 = 25 μm. The porous starch carrier was collected through a 200-mesh sieve. The specific surface area was determined by the BET method to be 285 m 2 / g, and the pore size distribution is 2-50nm.

[0058] Preparation Example 2

[0059] Preparation of the binder: Natural attapulgite clay was crushed to 200 mesh and calcined at 500°C for 2 hours to remove organic impurities. The calcined natural attapulgite clay was then mixed with CTAB at a weight ratio of 1:0.5. The mixture was stirred in a sodium hydroxide solution with a pH of 9.0 at 70°C for 4 hours, centrifuged and washed until no Br- residue was left. The mixture was then vacuum dried in a vacuum drying oven at 80°C for 6 hours to obtain the modified attapulgite clay. XRD analysis showed that the interlayer spacing of the modified attapulgite clay was enlarged to 4.1 nm, and the specific surface area was 195 m 2 / g; cross-linked sodium carboxymethyl cellulose, polyvinyl butyral and modified attapulgite clay are uniformly mixed in a weight ratio of 100:35:0.2 to obtain a binder.

[0060] Preparation Example 3

[0061] Preparation of inner coating liquid: By weight, 45 parts of ethyl cellulose, 6 parts of nano titanium dioxide (composed of anatase titanium dioxide and rutile titanium dioxide in a weight ratio of 7:3), 2.5 parts of triethyl citrate, and 1.5 parts of glyceryl monostearate are dissolved in anhydrous ethanol to form an inner coating liquid with a solid content of 13%.

[0062] Preparation Example 4

[0063] Prepare the outer coating liquid: dissolve 35 parts of polylactic acid, 12 parts of diatomaceous earth microspheres, 3 parts of magnesium stearate, and 2 parts of fumed silica in ethyl acetate according to weight to form an outer coating liquid with a solid content of 9%.

[0064] Example 1

[0065] Preparation of diuron granules:

[0066] Step 1: 100 g of diuron was mixed with 400 g of the porous starch carrier of Preparation Example 1, and then 3 g of sodium polyacrylate and 2 g of sodium dodecylnaphthalene sulfonate were added and mixed evenly. Then, the mixture was crushed by an ultrafine airflow mill at an airflow pressure of 1 MPa for 40 min to obtain pellets with a particle size D90 ≤ 10 μm, and the specific surface area of the pellets was 172 m 2 / g;

[0067] Step 2: The granules were placed in a fluidized bed granulator, and then the binder of Preparation Example 2 was sprayed into the granulator for granulation. During the granulation process, the inlet air temperature of the fluidized bed granulator was 50°C, the atomization pressure was 0.2 MPa, the spray rate was 12 mL / min, and the granulation time was 25 min. Finally, a masterbatch with a particle size of 0.8-1.2 mm was formed, totaling 515 g.

[0068] Step 3, first, 20.6g of the inner coating liquid of Preparation Example 3 was mixed and coated with the masterbatch in a pulsed fluidized bed, and then 51.5g of the outer coating liquid of Preparation Example 4 was mixed and coated with the masterbatch in a pulsed fluidized bed. During the coating process, the pulse frequency of the inner coating liquid and the outer coating liquid was 7Hz, the pulse waveform was a square wave, the duty cycle was 40%, the adsorption pressure was -0.04MPa, the single adsorption time was 4s, the interval time was 2.5s, the fluidizing gas velocity was 0.5m / s, the air flow temperature was 45°C, a dual-fluid atomizing spray gun was used, the atomizing air pressure was 0.35MPa, and the spray droplet size D50 was 65um; finally, a controlled release film and an anti-caking film were sequentially coated on the surface of the masterbatch to obtain granules;

[0069] Step 4: Use a three-dimensional screening device with a vibration frequency of 25 Hz and a mesh aperture of 1 mm to size-classify the granules, remove particles with unqualified particle size, and then enter a microwave-hot air coupled drying system with a microwave frequency of 2450 MHz, a power density of 0.8 W / g, a hot air temperature of 70°C, and a wind speed of 1.3 m / s until the moisture content is ≤0.5%. Finally, after electrostatic adsorption dust removal by a 40 kV high-voltage electrostatic precipitator, the granules are sealed and packaged in a nitrogen atmosphere with an oxygen content of ≤0.5% to obtain diuron granules.

[0070] Example 2

[0071] Compared with Example 1, the only difference is that some parameters are different, specifically:

[0072] In step 1: diuron 100g, porous starch carrier 300g, sodium polyacrylate 2g, sodium dodecylnaphthalene sulfonate 1g;

[0073] In step 2: the granulation time is 20 min, and the masterbatch obtained is 412 g in total;

[0074] In step 3: 12.36g of inner coating liquid and 32.96g of outer coating liquid;

[0075] Other conditions remained the same, and diuron granules were finally prepared.

[0076] Example 3

[0077] Compared with Example 1, the only difference is that some parameters are different, specifically:

[0078] In step 1: 100 g of diuron, 500 g of porous starch carrier, 5 g of sodium polyacrylate, and 3 g of sodium dodecylnaphthalene sulfonate;

[0079] In step 2: the granulation time is 30 min, and the masterbatch obtained is 622 g in total;

[0080] In step 3: 31.1g of inner coating liquid and 74.64g of outer coating liquid;

[0081] Other conditions remained the same, and diuron granules were finally prepared.

[0082] Example 4

[0083] Compared with Example 1, the only difference is that some parameters are different, specifically:

[0084] In step 4: the power density of the microwave-hot air coupled drying system is 0.5 W / g, the hot air temperature is 60°C, and the wind speed is 1.5 m / s;

[0085] Other conditions remained the same, and diuron granules were finally prepared.

[0086] Example 5

[0087] Compared with Example 1, the only difference is that some parameters are different, specifically:

[0088] In step 4: the power density of the microwave-hot air coupled drying system is 1.0 W / g, the hot air temperature is 80°C, and the wind speed is 1.2 m / s;

[0089] Other conditions remained the same, and diuron granules were finally prepared.

[0090] Comparative Example 1

[0091] Compared with Example 1, the only difference is that in step 1, the porous starch carrier of Preparation Example 1 is replaced by corn starch, and other conditions remain the same, and finally diuron granules are prepared.

[0092] Comparative Example 2

[0093] Compared with Example 1, the only difference is that in step 2, the binder is replaced by a composition consisting of cross-linked sodium carboxymethyl cellulose and polyvinyl butyral in a weight ratio of 100:35, and other conditions remain the same, and finally diuron granules are prepared.

[0094] Comparative Example 3

[0095] Compared with Example 1, the only difference is that in step 3, the coating operation of the outer coating liquid is cancelled, and other conditions remain the same, and finally diuron granules are obtained.

[0096] Comparative Example 4

[0097] Compared with Example 1, the only difference is that in step 3, the coating operation of the inner coating liquid is cancelled, and other conditions remain the same, and finally diuron granules are obtained.

[0098] The performance tests of the diuron granules prepared in Examples 1-5 and Comparative Examples 1-4 were conducted, including drug loading rate, disintegration rate, duration of effect, and compressive strength. The test methods were as follows:

[0099] Drug loading rate: refer to the General Rules 0512 of Part IV of the 2020 edition of the Chinese Pharmacopoeia;

[0100] Disintegration rate: Refer to FAO / WHO pesticide formulation quality standards (C IPAC MT 185);

[0101] Effective period: Refer to GB / T 17980.1-2000 "Guidelines for Field Efficacy Tests of Pesticides";

[0102] Compressive strength: Refer to ASTM D4179 test method.

[0103] The test results are listed in Table 1, which is as follows:

[0104] Table 1

[0105] Drug loading rate / 100% 30min disintegration rate / 100% Duration / day Compressive strength / N Example 1 91.5 98.5 120 19.5 Example 2 90.6 98.4 120 19.2 Example 3 91.1 98.5 120 18.9 Example 4 89.5 98.5 120 19.4 Example 5 90.9 98.4 120 19.2 Comparative Example 1 45.2 82.1 80 15.2 Comparative Example 2 75.2 85.5 95 10.1 Comparative Example 3 74.8 71.2 75 15.5 Comparative Example 4 76.2 73.6 72 15.4

[0106] Analysis of the data in Table 1 shows that, compared with Comparative Examples 1-4, the drug loading rate, disintegration rate, duration of effect and compressive strength of the diuron granules prepared in Examples 1-5 are significantly better, which indicates that the diuron granules of the present invention have better efficacy.

[0107] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A production process of diuron granules, characterized in that: The steps include: Step 1: mixing diuron and a porous starch carrier in a weight ratio of 1:(3-5), adding a dispersant and a wetting agent and mixing evenly, and then crushing by an ultrafine airflow mill to obtain granules; Step 2: Place the pellets in a fluidized bed granulator, then spray the binder into the granulator to form a masterbatch with a particle size of 0.8-1.2 mm; Step 3: coating the surface of the masterbatch with a controlled release membrane containing ethyl cellulose and nano-titanium dioxide and an anti-caking membrane containing polylactic acid and diatomaceous earth microspheres in a fluidized bed in sequence to obtain granules; Step 4: Use a three-dimensional screening device to size-classify the granules, combine with microwave-hot air coupling drying, and finally remove dust by electrostatic adsorption and then fill with nitrogen for packaging to obtain diuron granules.

2. The production process of diuron granules according to claim 1, characterized in that: In step one, the porous starch carrier is prepared by the following method: corn starch and α-amylase are enzymatically hydrolyzed in a buffer solution with a pH of 6.0 at a weight ratio of 19:1 for 30 minutes, and then treated with supercritical carbon dioxide fluid at a pressure of 15 MPa and a temperature of 45°C for 2 hours, followed by drying and crushing to obtain a porous starch carrier.

3. The production process of diuron granules according to claim 1, characterized in that: In step 1, the dispersant is polycarboxylate, and the weight ratio of the polycarboxylate to diuron is 100:(2-5).

4. The production process of diuron granules according to claim 1, characterized in that: In step 1, the wetting agent is alkylnaphthalene sulfonate, and the weight ratio of the alkylnaphthalene sulfonate to diuron is 100:(1-3).

5. The production process of diuron granules according to claim 1, characterized in that: In step 2, the air inlet temperature in the fluidized bed granulator is controlled at 45-55° C. and the atomization pressure is controlled at 0.15-0.25 MPa.

6. The production process of diuron granules according to claim 1, characterized in that: In step 2, the binder is composed of cross-linked sodium carboxymethyl cellulose, polyvinyl butyral ester and modified attapulgite clay in a weight ratio of 100:35:(0.1-0.3); wherein the modified attapulgite clay is prepared by the following method: natural attapulgite clay is crushed to 200 mesh, calcined at 500°C for 2h, and then the calcined natural attapulgite clay is mixed with hexadecyltrimethylammonium bromide in a weight ratio of 1:0.5, stirred at 70°C in an alkaline solution of pH 9.0 for 4h, and centrifuged and washed until there is no Br - The residue is vacuum dried to obtain modified attapulgite clay.

7. The production process of diuron granules according to claim 1, characterized in that: In step 3, the controlled release membrane accounts for 3-5 wt% of the masterbatch mass; The controlled release membrane comprises the following components in parts by weight: 40-50 parts of ethyl cellulose, 5-8 parts of nano titanium dioxide, 2-3 parts of triethyl citrate, and 1-2 parts of glyceryl monostearate; The controlled release membrane coating method comprises dissolving the components of the controlled release membrane in anhydrous ethanol in proportion to form an inner coating liquid with a solid content of 12-15%, and then mixing and coating the inner coating liquid with the masterbatch in a pulsed fluidized bed to obtain the masterbatch coated with the controlled release membrane.

8. The production process of diuron granules according to claim 7, characterized in that: The nano titanium dioxide is composed of anatase titanium dioxide and rutile titanium dioxide in a weight ratio of 7:

3.

9. The production process of diuron granules according to claim 1, characterized in that: In step 3, the anti-caking film accounts for 8-12 wt% of the masterbatch mass; The anti-caking film comprises the following components in parts by weight: 30-40 parts of polylactic acid, 10-15 parts of diatomaceous earth microspheres, 2-4 parts of magnesium stearate, and 1-3 parts of fumed silica; The coating method of the anti-caking film is as follows: the components of the anti-caking film are dissolved in ethyl acetate in proportion to form an outer coating liquid with a solid content of 8-10%, and then the outer coating liquid is mixed and coated with the masterbatch coated with the controlled release membrane in a pulsed fluidized bed to obtain the masterbatch coated with the anti-caking film.

10. A diuron granule, characterized in that: The diuron granules are prepared by the production process of diuron granules according to any one of claims 1 to 9.