Pendimethalin microcapsule suspending agent and preparation method thereof

Abstract

The invention belongs to the technical field of medicament preparation, and particularly relates to a pendimethalin microcapsule suspending agent and a preparation method thereof. The invention provides a pendimethalin microcapsule suspending agent. The pendimethalin microcapsule suspending agent is prepared from the following raw materials in parts by mass: 40-50 parts of pendimethalin, 1-4 parts of an oily wall material, 1-4 parts of a water-based wall material, 100-150 parts of water, 0.1-1 part of a defoaming agent, 0.5-2 parts of an emulsifying agent, 2-4 parts of a dispersing agent, 1-3 parts of xanthan gum and 8-12 parts of an anti-freezing agent. The pendimethalin microcapsule suspending agent provided by the invention takes water as a medium, so that the influence on the environment is greatly reduced, and the obtained microcapsule suspending agent has an excellent weed control effect and good environmental compatibility.

Description

Technical Field

[0001] The present invention belongs to the technical field of pharmaceutical preparation, and particularly relates to a pendimethalin microcapsule suspension and a preparation method thereof. Background Art

[0002] Pendimethalin is mainly used for weed control. Its advantages are that it is effective not only against monocotyledonous weeds but also against dicotyledonous weeds. The applicable period of application is relatively long, and it can be used from before sowing to after emergence of seedlings. It is an ideal component of a mixture and has good effects when used on crops such as corn, cotton, and wheat.

[0003] This medicament has been widely promoted, but the main dosage form is the emulsifiable concentrate dosage form, and there are still some problems at present: First, the emulsifiable concentrate dosage form contains a large amount of organic solvents, which is easy to cause environmental pollution; at the same time, it is relatively easy to adhere to the skin and other items during the application process, posing a potential danger. Second, it is highly toxic to aquatic organisms and poses a threat to water bodies when applied in areas with a relatively high groundwater level. Third, affected by soil types, temperature, humidity and other conditions in different regions, the effective period of the medicament is relatively short, affecting its application effect in the fields. Summary of the Invention

[0004] The purpose of the present invention is to provide a pendimethalin microcapsule suspension and a preparation method thereof. The pendimethalin microcapsule suspension prepared by the method provided by the present invention is safe and has a longer effective period of the medicament.

[0005] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a pendimethalin microcapsule suspension, which comprises the following raw materials for preparation in parts by mass:

[0007] 40 - 50 parts of pendimethalin, 1 - 4 parts of an oily wall material, 1 - 4 parts of an aqueous wall material, 100 - 150 parts of water, 0.1 - 1 part of an antifoaming agent, 0.5 - 2 parts of an emulsifier, 2 - 4 parts of a dispersant, 1 - 3 parts of xanthan gum, and 8 - 12 parts of an antifreeze.

[0008] Preferably, the oily wall material comprises at least one of TDI, MDI, IPDI, and polymeric MDI;

[0009] The aqueous wall material comprises at least one of ethylene glycol, glycerol, triethylenetetramine, polyethylene glycol, and ethylenediamine.

[0010] Preferably, the antifoaming agent comprises at least one of polydimethylsiloxane, composite silicone grease emulsion, and polyether antifoaming agent;

[0011] The emulsifier comprises at least one of emulsifier CRODA - 4913, emulsifier SP - 7215, emulsifier SP - 7213, and emulsifier SP - 27001;

[0012] The dispersant includes at least one of nonylphenol polyoxyethylene ether, polyvinyl alcohol, and alkyl sulfonate;

[0013] The antifreeze includes at least one of ethylene glycol, propylene glycol, urea, diethylene glycol, and glycerol.

[0014] The present invention also provides a method for preparing the pendimethalin microcapsule suspension agent according to the above technical solution, including the following steps:

[0015] Mix pendimethalin and an oily wall material for the first time to obtain a first material;

[0016] Mix the first part of water, an antifoaming agent, an emulsifier, and a dispersant for the second time to obtain a second material;

[0017] Mix the second part of water and an aqueous wall material for the third time to obtain a third material;

[0018] Mix the third part of water and xanthan gum for the fourth time to obtain a fourth material;

[0019] Mix the first material and the second material for the fifth time to obtain a fifth material;

[0020] Mix the third material and the fifth material for the sixth time to obtain a sixth material;

[0021] Mix the fourth material, the antifreeze, and the sixth material for the seventh time to obtain the pendimethalin microcapsule suspension agent.

[0022] Preferably, the temperature of the first mixing is 60-70 °C, and the first mixing is carried out under stirring conditions.

[0023] Preferably, the temperature of the second mixing is 60-70 °C, the second mixing is carried out under stirring conditions, and the stirring speed is 6000 rpm.

[0024] Preferably, the mass concentration of the aqueous wall material in the third material is 15-30%;

[0025] The mass concentration of xanthan gum in the fourth material is 1-3%.

[0026] Preferably, the process of the fifth mixing is: pouring the first material into the second material for shearing; the shearing speed is 10000-12000 rpm, the time is 1-5 min, and the temperature is 60-70 °C.

[0027] Preferably, the process of the sixth mixing is: dropping the third material into the fifth material, and the temperature of the sixth mixing is 60-70 °C.

[0028] Preferably, the process of the seventh mixing is: adding the fourth material and the antifreeze into the sixth material, and stirring to cool down.

[0029] The present invention provides a pendimethalin microcapsule suspension, which comprises the following raw materials for preparation in parts by mass: 40 - 50 parts of pendimethalin, 1 - 4 parts of oily wall material, 1 - 4 parts of aqueous wall material, 100 - 150 parts of water, 0.1 - 1 part of defoamer, 0.5 - 2 parts of emulsifier, 2 - 4 parts of dispersant, 1 - 3 parts of xanthan gum, and 8 - 12 parts of antifreeze.

[0030] Compared with the prior art, the advantages of the present invention are as follows:

[0031] (1) The amount of organic solvents is significantly reduced. Using water as the dispersion medium, it completely does not contain organic solvents such as xylene and cyclohexanone, reducing the emission of volatile organic compounds (VOCs);

[0032] (2) Enhanced biodegradability: The wall material of the microcapsules mostly adopts degradable polymers such as plant cellulose or urea - formaldehyde resin, reducing environmental residues;

[0033] (3) Improved safety. The microcapsule suspension can reduce the direct contact between the active ingredient and the crop roots, and is especially safer for solanaceous crops (such as tomatoes), while the emulsifiable concentrate is prone to root burning due to improper application;

[0034] (4) Convenient to use, allowing a wider time window for application before emergence after sowing, while the emulsifiable concentrate needs to be strictly applied within 5 days after sowing;

[0035] (5) Dosage form stability. The microcapsule suspension has no crystal precipitation during storage at - 5°C to 54°C, and the dumping qualification rate > 95%, while the emulsifiable concentrate has problems of easy crystallization at low temperature and easy volatilization at high temperature;

[0036] (6) The microcapsule suspension has a longer drug - effect period, with excellent weed control effect and good environmental compatibility.

[0037] The present invention also provides a preparation method of the pendimethalin microcapsule suspension described in the above technical solution. Traditional micro - capsule preparation technologies have rough preparation conditions during industrialization, resulting in low encapsulation efficiency of the obtained micro - capsules, uneven particle size distribution, and difficulty in precisely controlling the internal structure and release rate of the micro - capsules. The present invention adopts the interfacial polymerization method, which has the characteristics of high drug - loading capacity, high encapsulation efficiency, and easy control of the particle size of the micro - capsules compared with other methods, and is simple to operate, with mild conditions and fast speed, suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a microscope image of the microcapsule suspension obtained in Example 1 after heat storage;

[0039] Figure 2Microscopic image of the microcapsule suspension obtained in Example 1 after cold storage;

[0040] Figure 3 Particle size test results of the microcapsule suspension obtained in Example 1;

[0041] Figure 4 Physical image of the microcapsule suspension obtained in Example 1. Detailed implementation manners

[0042] The present invention provides a pendimethalin microcapsule suspension, which comprises the following raw materials for preparation in parts by mass:

[0043] 40 - 50 parts of pendimethalin, 1 - 4 parts of oily wall material, 1 - 4 parts of water-based wall material, 100 - 150 parts of water, 0.1 - 1 part of defoamer, 0.5 - 2 parts of emulsifier, 2 - 4 parts of dispersant, 1 - 3 parts of xanthan gum, and 8 - 12 parts of antifreeze.

[0044] In parts by mass, the raw materials for preparation of the pendimethalin microcapsule suspension provided by the present invention include 40 - 50 parts of pendimethalin, specifically 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 parts, 49 parts, 50 parts.

[0045] In parts by mass, the raw materials for preparation of the pendimethalin microcapsule suspension provided by the present invention include 1 - 4 parts of oily wall material, specifically 1 part, 2 parts, 3 parts, 4 parts. In the present invention, the oily wall material preferably includes at least one of TDI, MDI, IPDI, and polymeric MDI.

[0046] In parts by mass, the raw materials for preparation of the pendimethalin microcapsule suspension provided by the present invention include 1 - 4 parts of water-based wall material, specifically 1 part, 2 parts, 3 parts, 4 parts. In the present invention, the water-based wall material preferably includes at least one of ethylene glycol, glycerol, triethylenetetramine, polyethylene glycol, and ethylenediamine.

[0047] In parts by mass, the raw materials for preparation of the pendimethalin microcapsule suspension provided by the present invention include 100 - 150 parts of water, specifically 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, 150 parts.

[0048] In parts by mass, the raw materials for preparation of the pendimethalin microcapsule suspension provided by the present invention include 0.1 - 1 part of defoamer, specifically 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1.0 part. In the present invention, the defoamer preferably includes at least one of polydimethylsiloxane, composite silicone grease emulsion, and polyether defoamers.

[0049] In terms of parts by mass, the raw materials for preparing the pendimethalin microcapsule suspension provided by the present invention include 0.5 - 2 parts of an emulsifier, specifically 0.5 part, 0.8 part, 1.0 part, 1.2 parts, 1.5 parts, 1.8 parts, or 2.0 parts. In the present invention, the emulsifier preferably includes at least one of emulsifier CRODA - 4913, emulsifier SP - 7215, emulsifier SP - 7213, and emulsifier SP - 27001.

[0050] In terms of parts by mass, the raw materials for preparing the pendimethalin microcapsule suspension provided by the present invention include 2 - 4 parts of a dispersant, specifically 2 parts, 2.5 parts, 3.0 parts, 3.5 parts, or 4 parts. In the present invention, the dispersant preferably includes at least one of nonylphenol polyoxyethylene ether, polyvinyl alcohol, and alkyl sulfonate.

[0051] In terms of parts by mass, the raw materials for preparing the pendimethalin microcapsule suspension provided by the present invention include 1 - 3 parts of xanthan gum, specifically 1 part, 2 parts, or 3 parts. In the present invention, the xanthan gum is used as a thickener and stabilizer, which can further improve the stability of the suspension.

[0052] In terms of parts by mass, the raw materials for preparing the pendimethalin microcapsule suspension provided by the present invention include 8 - 12 parts of an antifreeze agent, specifically 8 parts, 9 parts, 10 parts, 11 parts, or 12 parts. In the present invention, the antifreeze agent preferably includes at least one of ethylene glycol, propylene glycol, urea, diethylene glycol, and glycerol.

[0053] The present invention also provides a method for preparing the pendimethalin microcapsule suspension according to the above - mentioned technical solution, including the following steps:

[0054] Mix pendimethalin and an oily wall material for the first time to obtain a first material;

[0055] Mix a first portion of water, an antifoaming agent, an emulsifier, and a dispersant for the second time to obtain a second material;

[0056] Mix a second portion of water and an aqueous wall material for the third time to obtain a third material;

[0057] Mix a third portion of water and xanthan gum for the fourth time to obtain a fourth material;

[0058] Mix the first material and the second material for the fifth time to obtain a fifth material;

[0059] Mix the third material and the fifth material for the sixth time to obtain a sixth material;

[0060] Mix the fourth material, the antifreeze agent, and the sixth material for the seventh time to obtain the pendimethalin microcapsule suspension.

[0061] The present invention first mixes pendimethalin and an oily wall material to obtain a first material. In the present invention, the temperature of the first mixing is preferably 60-70 °C, and the first mixing is preferably carried out under stirring conditions.

[0062] The present invention second mixes a first portion of water, an antifoaming agent, an emulsifier, and a dispersant to obtain a second material. In the present invention, the temperature of the second mixing is preferably 60-70 °C, the second mixing is preferably carried out under stirring conditions, and the stirring speed is preferably 6000 rpm.

[0063] The present invention third mixes a second portion of water and an aqueous wall material to obtain a third material; and fourth mixes a third portion of water and xanthan gum to obtain a fourth material. The present invention has no special limitation on the processes of the third mixing and the fourth mixing, and those well-known to those skilled in the art can be used. In the present invention, the mass concentration of the aqueous wall material in the third material is preferably 10-30%, more preferably 15-20%; the mass concentration of xanthan gum in the fourth material is preferably 1-3%, more preferably 1.5-2.1%.

[0064] After obtaining the first material and the second material, the present invention fifth mixes the first material and the second material to obtain a fifth material. In the present invention, the process of the fifth mixing is preferably: pouring the first material into the second material for shearing; the shearing speed is preferably 10000-12000 rpm, the time is preferably 1-5 min, and the temperature is preferably 60-70 °C.

[0065] After obtaining the fifth material and the third material, the present invention sixth mixes the third material and the fifth material to obtain a sixth material. In the present invention, the process of the sixth mixing is preferably: dropping the third material into the fifth material; the dropping rate is 2-3 mL / min; the temperature of the sixth mixing is preferably 60-70 °C. In the present invention, during the process of the sixth mixing, by controlling the temperature at 60-70 °C, the reaction can be made gentle, and the obtained particles have a uniform particle size distribution and a smooth surface; if the temperature is too low, the curing reaction will be slow, the yield will be low, the particle surface will be rough, the particle size will be large, and even the curing will not occur; if the temperature is too high, the curing reaction will be too fast, and the obtained particles will adhere to each other.

[0066] After obtaining the sixth material and the fourth material, the present invention seventh mixes the fourth material, an antifreeze agent, and the sixth material to obtain the pendimethalin microcapsule suspension. In the present invention, the process of the seventh mixing is preferably: adding the fourth material and the antifreeze agent to the sixth material and stirring to cool down. In the present invention, the temperature of the system after cooling is preferably 30 °C.

[0067] In the present invention, the particle size D50 of the pendimethalin microcapsule suspension is preferably 1 - 6 μm, and D90 is preferably 5 - 13 μm.

[0068] Unless otherwise specified, the materials and equipment used in the present invention are commercially available products in the art.

[0069] The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0070] Example 1

[0071] Heat 45 g of pendimethalin and 3 g of polymeric MDI to 65 °C and stir evenly to obtain the first material.

[0072] Mix 28 g of water, 0.1 g of polydimethylsiloxane, 1 g of emulsifier SP - 7215, and 3 g of polyvinyl alcohol and stir evenly at a stirring speed of 6000 rpm and a temperature of 60 °C to obtain the second material.

[0073] Mix 3 g of polyethylene glycol and water to prepare an aqueous polyethylene glycol solution with a mass concentration of 20% to obtain the third material.

[0074] Mix 2 g of xanthan gum and water to prepare a xanthan gum mother liquor with a mass concentration of 2.1% to obtain the fourth material.

[0075] Pour the first material into the second material, shear at 12000 rpm for 5 min at a temperature of 60 °C to obtain the fifth material.

[0076] Drop the third material into the fifth material at a rate of 3 mL / min at a temperature of 60 °C to obtain the sixth material.

[0077] Add the fourth material and 8 g of propylene glycol to the sixth material, stir and cool down to 30 °C to obtain the pendimethalin microcapsule suspension. The physical picture obtained is as Figure 4 shown.

[0078] Example 2

[0079] Prepare the pendimethalin microcapsule suspension in the same manner as in Example 1, except that 40 g of pendimethalin and 1.8 g of polymeric MDI are used.

[0080] Example 3

[0081] The pendimethalin microcapsule suspension was prepared in the same manner as in Example 1, except that 1.8 g of polymeric MDI was added; in the fifth mixing, the first material was poured into the second material and sheared at 10,000 rpm for 1.5 min.

[0082] Comparative Example 1

[0083] The pendimethalin microcapsule suspension was prepared in the same manner as in Example 1, except that in the sixth mixing, the temperature of dropping the third material into the fifth material was controlled at 35 °C.

[0084] Comparative Example 2

[0085] The pendimethalin microcapsule suspension was prepared in the same manner as in Example 1, except that in the sixth mixing, the temperature of dropping the third material into the fifth material was controlled at 75 °C.

[0086] Performance Test

[0087] Test Example 1

[0088] The suspensions obtained in the examples and comparative examples were respectively tested for heat storage, cold storage and encapsulation rate. The test conditions for heat storage were as follows: the suspension was filled into a container, sealed and placed in a constant temperature oven at (54 ± 2) °C, taken out after standing for 14 days, and the appearance was observed; the test conditions for cold storage were as follows: the suspension was filled into a container, sealed and left to stand at 0 °C for 14 days, and then taken out to observe the appearance.

[0089] The results obtained are shown in Table 1:

[0090] Table 1 Stability test results of the suspensions in the examples and comparative examples

[0091] Entrapment efficiency / % Thermal storage stability Cold storage stability Example 1 99.3 Good fluidity, no delamination or caking Good fluidity, no delamination or caking Example 2 98.9 Good fluidity, no delamination or caking Good fluidity, no delamination or caking Example 3 98.4 Good fluidity, no delamination or caking Good fluidity, no delamination or caking Comparative Example 1 76.2 Average fluidity, caking Poor fluidity, caking Comparative Example 2 84.1 Average fluidity, caking Average fluidity, caking

[0092] Figure 1 Microscopic image of the microcapsule suspension obtained in Example 1 after heat storage; Figure 2 Microscopic image of the microcapsule suspension obtained in Example 1 after cold storage; Figure 3 Particle size test results of the microcapsule suspension obtained in Example 1, from Figures 1 - 3 It can be seen that the suspension provided by the present invention has stable performance and can maintain good fluidity after cold storage and heat storage.

[0093] Test Example 2

[0094] The suspensions obtained in the examples and comparative examples were tested in accordance with "450 g / L Pendimethalin Microcapsule Suspension" (an industry standard implemented on March 1, 2019), and the specific results obtained are shown in Table 2;

[0095] Table 2 Performance test results of the suspensions obtained in the examples and comparative examples

[0096] Test Index Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Mass concentration 450 ± 22.5 g / L 458 458 459 460 452 Mass fraction 38.5±1.9(％) 38.9 39.0 39.0 39.0 39.0 pH 7.0～10 9.0 9.1 9.0 8.9 8.8 Density <![CDATA[1.17~1.19(g / cm 3 )]]> 1.177 1.175 1.177 1.179 1.181 Free ≤3.8(％) 0.20 0.15 0.10 4.30 5.40

[0097] As can be seen from Table 2, the free value of the suspending agent obtained in the present invention meets the requirements of the indicators, indicating that the technical drug in the obtained suspending agent is all encapsulated in the capsules, while the free values of Comparative Example 1 and Comparative Example 2 exceed the standard, indicating that there is technical drug not encapsulated in the capsules.

[0098] Test Example 3

[0099] The efficacy of the suspending agent obtained in Test Example 1 against annual weeds in cotton fields was tested, with 330 g / L pendimethalin emulsifiable concentrate as the blank control;

[0100] Among them, the cotton variety was Guoshen Cotton 668, and the annual weeds were mainly Digitaria sanguinalis and Commelina bengalensis;

[0101] Cultivation conditions: The soil type was lime concretion black soil, with an organic matter content of 1.80%, available nitrogen of 198.41 mg / kg, available phosphorus of 22.78 mg / kg, available potassium of 103.78 mg / kg, pH 7.10, and the tillage method was rotary tillage. The tested cotton was planted by manually opening holes for dibbling, with a seeding rate of 0.9 kg / mu.

[0102] Tested agents: The suspending agent obtained in Example 1 and 330 g / L pendimethalin emulsifiable concentrate;

[0103] The dosage was 175 mL / mu;

[0104] Efficacy calculation method:

[0105]

[0106] The obtained test results are shown in Table 3;

[0107] Table 3 Efficacy test results of the suspending agent obtained in the example

[0108]

[0109] Although the above embodiments have described the present invention in detail, they are only some embodiments of the present invention, rather than all embodiments. Other embodiments can be obtained based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A pendimethalin microcapsule suspension, characterized in that, It includes the following raw materials for preparation in parts by mass: 40 - 50 parts of pendimethalin, 1 - 4 parts of oil-based wall material, 1 - 4 parts of water-based wall material, 100 - 150 parts of water, 0.1 - 1 part of defoamer, 0.5 - 2 parts of emulsifier, 2 - 4 parts of dispersant, 1 - 3 parts of xanthan gum, and 8 - 12 parts of antifreeze agent.

2. The pendimethalin microcapsule suspension according to claim 1, wherein, The oil-based wall material includes at least one of TDI, MDI, IPDI, and polymeric MDI; The water-based wall material includes at least one of ethylene glycol, glycerol, triethylenetetramine, polyethylene glycol, and ethylenediamine; 3. The pendimethalin microcapsule suspension according to claim 1, wherein, The defoamer includes at least one of polydimethylsiloxane, composite silicone grease emulsion, and polyether defoamer; The emulsifier includes at least one of emulsifier CRODA - 4913, emulsifier SP - 7215, emulsifier SP - 7213, and emulsifier SP - 27001; The dispersant includes at least one of nonylphenol polyoxyethylene ether, polyvinyl alcohol, and alkyl sulfonate; The antifreeze agent includes at least one of ethylene glycol, propylene glycol, urea, diethylene glycol, and glycerol.

4. The preparation method of the pendimethalin microcapsule suspension agent according to any one of claims 1 to 3, characterized in that, It includes the following steps: First mix pendimethalin and the oil-based wall material to obtain the first material; Second mix the first part of water, defoamer, emulsifier, and dispersant to obtain the second material; Third mix the second part of water and the water-based wall material to obtain the third material; Fourth mix the third part of water and xanthan gum to obtain the fourth material; Fifth mix the first material and the second material to obtain the fifth material; Sixth mix the third material and the fifth material to obtain the sixth material; Seventh mix the fourth material, antifreeze agent, and the sixth material to obtain the pendimethalin microcapsule suspension.

5. The preparation method according to claim 4, characterized in that, The temperature of the first mixing is 60 - 70°C, and the first mixing is carried out under stirring.

6. The preparation method according to claim 4, characterized in that, The temperature of the second mixing is 60 - 70°C, the second mixing is carried out under stirring, and the stirring speed is 6000 rpm.

7. The preparation method according to claim 4, characterized in that, The mass concentration of the water-based wall material in the third material is 15 - 30%; The mass concentration of xanthan gum in the fourth material is 1 - 3%.

8. The preparation method according to claim 4, characterized in that, The process of the fifth mixing is: pour the first material into the second material for shearing; the shearing speed is 10000 - 12000 rpm, the time is 1 - 5 min, and the temperature is 60 - 70°C.

9. The preparation method according to claim 4, characterized in that, The process of the sixth mixing is: drop the third material into the fifth material, and the temperature of the sixth mixing is 60 - 70°C.

10. The preparation method according to claim 4, characterized in that, The process of the seventh mixing is: add the fourth material and the antifreeze agent to the sixth material and stir to cool down.

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