A pesticide microcapsule suspension with degradable capsule wall and preparation method thereof

Abstract

The present application relates to the field of pesticides, and specifically discloses a kind of pesticide microcapsule suspension with degradable capsule wall and its preparation method, and the raw material of pesticide microcapsule suspension includes the following components by weight: 5-50 parts of original medicine, 2-10 parts of isocyanate prepolymer, 3-5 parts of emulsifier, 2-4 parts of dispersant, 0.1-0.5 parts of curing agent, 1.2-7.5 parts of other auxiliary agents; the preparation raw material of the isocyanate prepolymer includes the following components: isocyanate, polyol, the isocyanate is L-lysine ethyl diisocyanate, and the polyol is at least one of vegetable oil polyol, poly (ε-caprolactone) diol, and polylactic acid polyol. The microcapsule formed in the present application can stably wrap the original medicine, improve the stability of the original medicine, and the wall material has good biodegradability, and the degradation product has no toxic side effects, which reduces the pollution to the environment.

Description

Technical Field

[0001] The present application relates to the field of pesticides, and more specifically, to a pesticide microcapsule suspension with degradable capsule walls and a preparation method thereof. Background Art

[0002] Pesticides play an important role in agricultural production. Pesticides can be used to kill insects, fungi and other organisms that harm crop growth, and can also be used to prevent crop diseases and pests. With social development and technological progress, pesticides can be divided into wettable powders, soluble powders, emulsions, emulsifiable concentrates, concentrated emulsions, creams, suspensions, etc. according to the processing dosage form. Among them, suspensions do not have the dust problem of powders, and suspensions have the advantages of being non-flammable and non-explosive, high in biological activity, and safe and environmentally friendly compared to other pesticide dosage forms, and have been widely used.

[0003] However, there are also problems in the use of pesticides, such as loss of original medicine due to volatilization of pesticides, deterioration of original medicine during storage, etc. Therefore, people have introduced microcapsule technology into pesticide suspensions. Pesticide microencapsulation technology uses polymer substrates as capsule walls or capsule membranes, and uses chemical, physical or physicochemical methods to encapsulate active substances such as original medicines to form microcapsules with core (shell) structures and sustained-release effects. Compared with conventional pesticides, since the active ingredients of pesticides are encapsulated in a closed or semi-permeable membrane, the stability of the original medicine is improved, the loss caused by the volatilization of pesticides is reduced, and the sustained-release effect can be used to extend the effective period of the pesticide.

[0004] Commonly used wall materials for pesticide microcapsule suspensions include polyurethane, polyurea, urea-formaldehyde resin, melamine resin, etc. A common method for preparing pesticide microcapsule suspensions is: polyisocyanate prepolymer and original drug are used as oil phase, and then the oil phase is emulsified with the water phase, and then cross-linked and cured to form a microcapsule shell. The formed microcapsules can well encapsulate the original drug, improve the original drug encapsulation rate, and improve the stability of the pesticide suspension.

[0005] However, the polyisocyanate prepolymer used, on the one hand, forms a capsule wall that is difficult to degrade, and on the other hand, the degradation products are toxic to the environment to a certain extent, which is inconsistent with the current concept of green pesticides. Summary of the invention

[0006] The present application provides a pesticide microcapsule suspension with a degradable capsule wall and a preparation method thereof. The formed microcapsule structure can stably encapsulate the original drug, thereby improving the stability of the original drug. In addition, the wall material has good biodegradability, and the degradation product has no toxic side effects, thereby reducing pollution to the environment.

[0007] In the first aspect, the present application provides a pesticide microcapsule suspension with a degradable capsule wall, adopting the following technical scheme: a pesticide microcapsule suspension with a degradable capsule wall, the raw materials comprising the following components by weight: 5-50 parts of original drug, 2-10 parts of isocyanate prepolymer, 3-5 parts of emulsifier, 2-4 parts of dispersant, 0.1-0.5 parts of curing agent, and 1.2-7.5 parts of other additives; the raw materials for preparing the isocyanate prepolymer include the following components: isocyanate, polyol, the isocyanate is L-lysine ethyl diisocyanate, and the polyol is at least one of vegetable oil polyol, poly (ε-caprolactone) diol, and polylactic acid polyol.

[0008] By adopting the above technical scheme, L-lysine ethyl diisocyanate is selected as an isocyanate monomer. On the one hand, the main chain of L-lysine ethyl diisocyanate has a flexible aliphatic structure, so it can be well degraded, and the final degradation product is carbon dioxide and water; at the same time, vegetable oil polyols, poly (ε-caprolactone) diols, and polylactic acid polyols are also degradable substances, so that the prepared wall material has good biodegradability, and the degradation product has no toxic side effects, which reduces the pollution to the environment. On the other hand, vegetable oil polyols, poly (ε-caprolactone) diols, and polylactic acid polyols can be better compounded with L-lysine ethyl diisocyanate, respectively, and the original medicine can be well coated, with excellent encapsulation rate, and the prevention effect of subsequent pesticides is improved, so that the application can stably wrap the original medicine, improve the stability of the original medicine, and the wall material has good biodegradability, and the degradation product has no toxic side effects, which reduces the pollution to the environment.

[0009] Preferably, the emulsifier includes at least one of ammonium salt of styrene-maleic anhydride copolymer, alkylbenzene sulfonate, and alkyl carboxylate.

[0010] Preferably, the dispersant is at least one of naphthalene sulfonates, lignin sulfonates, naphthalene sulfonate formaldehyde condensates, alkylphenol polyoxyethylene ether formaldehyde condensates, and tristyrylphenol polyoxyethylene ethers.

[0011] Preferably, the other additives include antifreeze, defoaming agent and viscosity regulator; further, the antifreeze is at least one of ethylene glycol, glycerol, propylene glycol or urea; the viscosity regulator is at least one of xanthan gum, magnesium aluminum silicate, hydroxyethyl cellulose and white carbon black, and the defoaming agent is at least one of long-chain fatty alcohol, fatty acid ester, tributyl phosphate, polyether and polyether-modified silicone.

[0012] By adopting the above technical solution, the addition of antifreeze, defoaming agent and viscosity regulator, and the cooperation with other substances, the suspension system can be made more stable and the performance of the pesticide microcapsule suspension can be further improved.

[0013] The curing agent includes at least one of starch, cellulose, lignin, chitosan, sodium alginate and polylactic acid.

[0014] Preferably, the raw materials for preparing the isocyanate prepolymer also include the following components: polydopamine-modified silica; the raw materials for the polydopamine-modified silica include the following components: nano-silicon dioxide, dopamine hydrochloride, and the mass ratio of the nano-silicon dioxide to the dopamine hydrochloride is 1:(0.1-0.25).

[0015] By adopting the above technical scheme, polydopamine-modified silica can be obtained after the reaction of nano-silica and dopamine hydrochloride. On the one hand, the polydopamine-modified silica can be well grafted and attached to the surface of the microcapsule, thereby improving the roughness of the microcapsule surface and the adhesion of the microcapsule on the plant leaves, thereby improving the resistance of the pesticide to rain erosion and improving the efficacy of the pesticide; and in the polydopamine-modified silica, the surface of the polydopamine has a large number of hydroxyl, carboxyl, amino and other groups, which can improve the directional adsorption of the microcapsule on different parts of the plant, thereby improving the resistance of the pesticide to rain erosion and improving the efficacy of the pesticide.

[0016] Preferably, the mass ratio of the isocyanate to the polydopamine-modified silica is 1:(0.012-0.021).

[0017] By adopting the above technical solution and controlling the amount of polydopamine-modified silica added, the polydopamine-modified silica can be better bound to the surface of the microcapsule. On the one hand, too little polydopamine-modified silica may directly reduce the amount of polydopamine-modified silica bound to the surface of the microcapsule. On the other hand, too much polydopamine-modified silica will affect the encapsulation effect of the microcapsule itself on the original drug.

[0018] In a second aspect, the present application provides a method for preparing a pesticide microcapsule suspension with degradable capsule wall, using the following technical solution:

[0019] A method for preparing a pesticide microcapsule suspension with degradable capsule wall comprises the following steps:

[0020] The isocyanate and the polyol are mixed and reacted to obtain L-lysine ethyl ester diisocyanate prepolymer;

[0021] The technical and L-lysine ethyl ester diisocyanate prepolymer are uniformly mixed to obtain an oil phase;

[0022] adding an emulsifier and a dispersant into water and mixing to obtain an aqueous phase;

[0023] The oil phase and the water phase are mixed and emulsified to obtain an emulsion, a curing agent is added to the emulsion, and a microcapsule emulsion is obtained by reaction; a viscosity regulator, a defoaming agent, a dispersant and an antifreeze agent are added to the microcapsule emulsion to obtain a pesticide microcapsule suspension.

[0024] Optionally, nano-silica and dopamine hydrochloride are reacted to prepare polydopamine-modified silica; after turbidity appears during the mixed reaction of isocyanate and polyol, the polydopamine-modified silica is added to the mixed system of isocyanate and polyol.

[0025] By adopting the above technical solution, after turbidity appears in the mixed reaction of isocyanate and polyol, polydopamine-modified silica is added. On the one hand, the polydopamine-modified silica can be better bonded to the surface of the microcapsule, and on the other hand, the influence of the polydopamine-modified silica on the microcapsule encapsulation process of the original drug is reduced.

[0026] In summary, this application has the following beneficial effects:

[0027] 1. The present application selects degradable L-lysine ethyl ester diisocyanate as the isocyanate monomer, and combines it with degradable vegetable oil polyols, poly(ε-caprolactone) diols, and polylactic acid polyols, so that the prepared wall material has good biodegradability, and the generated wall material can also well coat the original drug, thereby improving the stability of the original drug.

[0028] 2. The present application also adds polydopamine-modified silica, and the polydopamine-modified silica is well bonded to the surface of the microcapsule, which can improve the surface roughness of the microcapsule on the one hand, and on the other hand, the hydroxyl groups of polydopamine and nano-silica can be used to improve the adhesion of the microcapsule on the plant leaf surface, thereby improving the resistance of the pesticide to rain erosion and improving the protective effect of the pesticide. DETAILED DESCRIPTION

[0029] The present application is further described in detail below with reference to the embodiments.

[0030] Preparation Example of Isocyanate Prepolymer

[0031] The materials in this preparation example can all be obtained from commercial sources. Specifically, the vegetable oil polyol is castor oil, and the molecular weight of the poly(ε-caprolactone) diol is 700.

[0032] Preparation Example 1

[0033] Preparation Example 1 provides an isocyanate prepolymer, and its preparation raw materials include isocyanate and polyol; wherein the isocyanate is L-lysine ethyl diisocyanate, and the polyol is vegetable oil polyol.

[0034] Preparation Example 1 provides a method for preparing an isocyanate prepolymer, comprising the following steps:

[0035] 500 g of L-lysine ethyl ester diisocyanate and 150 g of vegetable oil polyol were reacted under a nitrogen atmosphere at 50° C. and 300 rpm for 3.5 hours, and then cooled to room temperature to obtain an isocyanate prepolymer.

[0036] Preparation Example 2

[0037] The difference between Preparation Example 2 and Preparation Example 1 is that the polyol is poly(ε-caprolactone) diol.

[0038] Preparation Example 3

[0039] The difference between Preparation Example 3 and Preparation Example 1 is that the polyol is polylactic acid polyol, which is polylactic acid diol synthesized by the reaction of lactide and 1,6-hexanediol, and has a molecular weight of 1200.

[0040] Preparation Example 4

[0041] The difference between Preparation Example 4 and Preparation Example 1 is that the polyol is a mixture of poly(ε-caprolactone) diol and polylactic acid polyol in a mass ratio of 1:1.

[0042] Preparation Example 5

[0043] The difference between Preparation Example 5 and Preparation Example 1 is that the polyol is a mixture of vegetable oil polyol and polylactic acid polyol in a mass ratio of 1:1.

[0044] Preparation Example 6

[0045] The difference between Preparation Example 6 and Preparation Example 4 is that the raw materials for preparing the isocyanate prepolymer also include: polydopamine-modified silica, and the amount of isocyanate and polydopamine-modified silica is used in a mass ratio of 1:0.012; the raw materials for preparing the polydopamine-modified silica include nano-silica and dopamine hydrochloride, the particle size of the nano-silica is 15-17 nanometers, and the amount of nano-silica and dopamine hydrochloride is used in a mass ratio of 1:0.1.

[0046] Preparation Example 6 also provides a method for preparing an isocyanate prepolymer, comprising the following steps:

[0047] 10 g of nano-silicon dioxide and 0.3 g of sodium hexametaphosphate were added to 1500 ml of water, and a suspension was obtained after ultrasonic dispersion. The pH value was adjusted to 8.4 with a 5 wt % hydrochloric acid solution, and 1 g of dopamine hydrochloride was added to the suspension. After stirring for 25 hours, the reaction liquid was separated and dried to obtain polydopamine-modified silica.

[0048] 500 g of L-lysine ethyl ester diisocyanate and 150 g of vegetable oil polyol were reacted under a nitrogen atmosphere at 50° C. and 300 rpm. When the reaction liquid became turbid, 6 g of polydopamine-modified silica was added to the reaction liquid. The temperature was raised to 70° C. The total reaction time was 3.5 hours. After cooling to room temperature, an isocyanate prepolymer was obtained.

[0049] Preparation Example 7-10

[0050] The difference between Preparation Examples 7-10 and Preparation Example 6 is that the raw materials used in the preparation of the isocyanate prepolymer are different, as shown in Table 1.

[0051] Table 1 Raw materials of isocyanate prepolymers of Preparation Examples 6-7 (unit: g)

[0052]

[0053] Preparation Example 11

[0054] The difference between Preparation Example 11 and Preparation Example 7 is that:

[0055] 500 g of L-lysine ethyl ester diisocyanate and 150 g of vegetable oil polyol were reacted under a nitrogen atmosphere at 50° C. and 300 rpm. 20 minutes after the reaction liquid became turbid, 8 g of polydopamine-modified silica was added to the reaction liquid. The temperature was raised to 70° C. The total reaction time was 3.5 hours. After cooling to room temperature, an isocyanate prepolymer was obtained.

[0056] Preparation Example 12

[0057] The difference between Preparation Example 12 and Preparation Example 7 is that:

[0058] 500 g of L-lysine ethyl ester diisocyanate, 150 g of vegetable oil polyol, and 8 g of polydopamine-modified silica were mixed, and reacted under a nitrogen atmosphere at 60° C. and 300 rpm for a total reaction time of 3.5 hours. After cooling to room temperature, an isocyanate prepolymer was obtained.

[0059] Example

[0060] Example 1

[0061] Example 1 provides a pesticide microcapsule suspension with a degradable capsule wall. The raw materials include the following components by weight: 5g of original drug, 2g of isocyanate prepolymer, kg of emulsifier, kg of dispersant, 0.1g of curing agent, 1g of antifreeze agent, 0.1g of viscosity regulator, and 0.1g of defoaming agent.

[0062] The original drug in this embodiment is diazinon.

[0063] The emulsifier is sodium dodecylbenzene sulfonate.

[0064] The dispersant is tristyrylphenol polyoxyethylene ether, CAS: 99734-09-5.

[0065] The curing agent is sodium alginate.

[0066] The viscosity modifier is xanthan gum.

[0067] The antifreeze is ethylene glycol.

[0068] The defoaming agent is tributyl phosphate.

[0069] This embodiment also provides a method for preparing a pesticide microcapsule suspension with degradable capsule wall, comprising the following steps:

[0070] The technical and L-lysine ethyl ester diisocyanate prepolymer are uniformly mixed to obtain an oil phase;

[0071] adding an emulsifier and a dispersant into water and mixing to obtain an aqueous phase;

[0072] The oil phase and the water phase are mixed and emulsified to obtain an emulsion, a curing agent is added to the emulsion, and a microcapsule emulsion is obtained by reaction; a viscosity regulator, a dispersant, a defoaming agent and an antifreeze agent are added to the microcapsule emulsion, and the mixture is evenly mixed to obtain a pesticide microcapsule suspension.

[0073] Example 2-13

[0074] The difference between Example 2-13 and Example 1 is that the raw material content is different, see Table 2 for details.

[0075] Table 2 Raw materials of Examples 1-13 (unit: g)

[0076]

[0077]

[0078] Embodiment 13

[0079] The difference between Example 13 and Example 1 is that in Example 13, the emulsifier is sodium dodecylbenzene sulfonate, the dispersant is sodium lignin sulfonate, the curing agent is starch, the viscosity modifier is magnesium aluminum silicate, the antifreeze agent is glycerol, and the defoaming agent is polypropylene glycol with a molecular weight of 400.

[0080] Embodiment 14

[0081] The difference between Example 14 and Example 1 is that in Example 13, the emulsifier is ammonium salt of styrene-maleic anhydride copolymer, CAS No.: 26022-09-3. The dispersant is naphthalenesulfonate formaldehyde condensation product. The curing agent is chitosan. The viscosity modifier is xanthan gum. The antifreeze agent is glycerol. The defoaming agent is tributyl phosphate.

[0082] Comparative Example

[0083] Comparative Example 1

[0084] The difference between Comparative Example 1 and Example 1 is that the polyol is polyethylene oxide glycol with a molecular weight of 400.

[0085] Comparative Example 2

[0086] The difference between Comparative Example 2 and Example 1 is that the polyol is polyoxypropylene glycol with a molecular weight of 400.

[0087] Performance testing

[0088] The pesticide microcapsule suspensions obtained in the examples and comparative examples were subjected to the following performance tests:

[0089] 1. Determination of microcapsule encapsulation efficiency:

[0090] Take 1g of pesticide microcapsule suspension sample, put the sample and methanol water solution into a 100ml volumetric flask, the volume ratio of methanol to water is 1:1, dilute to 100ml and let stand, take the liquid sample and centrifuge, measure the absorbance of the centrifuge by ultraviolet spectrophotometry, and calculate the original drug mass M1 by comparing with the standard curve. Then ultrasonicate the volumetric flask for 20min, remove the liquid sample, measure the absorbance of the centrifuge by ultraviolet spectrophotometry, and calculate the original drug mass M2 by comparing with the standard curve. Then the encapsulation efficiency of the pesticide microcapsule suspension = (M2-M1) / the mass of the pesticide microcapsule suspension sample.

[0091] 2. Rainwater erosion test:

[0092] ① Preparation of liquid medicine: Add water to the suspension prepared in the examples and comparative examples to prepare a uniform liquid medicine containing 0.1 wt% of the original drug component.

[0093] ② Use a pipette to take 1 μl of each pesticide microcapsule suspension and drop it on clean rice leaves. Drop three rice leaves with each pesticide microcapsule suspension. Place them in a 30℃ incubator to dry for 3 hours. Take pictures of the dried slides under a microscope.

[0094] ③ Rainwater scouring treatment: Place the rice leaves at a 60-degree angle under a spray tower, spray 1L of water, dry them in a 30℃ incubator after spraying, and take pictures under a microscope;

[0095] ④Data processing and calculation: Use software to calculate the area of ​​drug spots on rice leaves before and after spraying, and the ratio of the area of ​​drug spots after / before spraying can be used to obtain the rain resistance effect.

[0096] 3. Field trials:

[0097] According to the test method in the "Guidelines for Field Efficacy Tests of Pesticides (NY / T1464.32-2010)", the suspension concentrate obtained in the examples and comparative examples was subjected to field tests for controlling peanut bacterial wilt.

[0098] Application method: spray the pesticide for the first time when the diseased plants are first seen, and spray the pesticide for the second time 7 days later. Apply the pesticide twice in total, set up 6 plots, each with an area of ​​20m 2 , repeated 4 times, a total of 24 plots. The dosage of active ingredient is 10g / 667m 2 .

[0099] Investigation method: 7d and 14d after the second application of pesticides, investigate all plants in each plot, record the total number of plants and the number of diseased plants, and calculate the control effect.

[0100] The test results are shown in Table 3

[0101] Table 3 Performance test table of pesticide microcapsule suspension

[0102]

[0103]

[0104] As can be seen from Examples 1-4, the present application can coat the pesticide original drug well, and has good drug efficacy, among which the overall technical effect of Example 4 is the best. Among them, the original drug content is the highest in Example 3, but the effect is not as good as other embodiments, which may be because the original drug is too much, affecting the reason why the microcapsule is coated. In addition, it can be seen from the test results of Comparative Examples 1 and 2 that after replacing the polyol, the various effects of the pesticide decrease, which may be because there is a better reaction and compounding effect between the L-lysine ethyl diisocyanate of the present application and the corresponding polyol. In addition, the test results of Example 4 and Example 5 are analyzed to find that the effect of Example 4 is better than that of Example 5, and Example 5 only uses different polyols from Example 4, indicating that the compounding effect of L-lysine ethyl diisocyanate and poly (ε-caprolactone) diol, polylactic acid polyol is better than the compounding effect of L-lysine ethyl diisocyanate and vegetable oil polyol, polylactic acid polyol.

[0105] From the test results of Examples 6 to 8, it can be seen that after the addition of polydopamine-modified silica, the coverage rate of the pesticide does not change much, but the resistance of the pesticide to rain erosion is greatly improved, and the protective effect of the pesticide is further improved. Among them, Example 7 has the best overall effect, which indicates that dopamine-modified silica is attached to the surface of the microcapsule, thereby improving the adhesion effect of the pesticide on the leaves.

[0106] However, the test results of Example 9 and Example 10 show that no matter too much polydopamine-modified silica is added or too little polydopamine-modified silica is added, the effect of the pesticide is reduced. In comparison, the adhesion rate of adding too little polydopamine-modified silica is worse, indicating that adding too little polydopamine-modified silica makes it impossible for polydopamine-modified silica to adhere well to the surface of the microcapsule. However, adding too much polydopamine-modified silica does not make the adhesion of the pesticide better, but further reduces the encapsulation rate and efficacy. This may be because too much polydopamine-modified silica affects the formation of the microcapsule or a part of the polydopamine-modified silica is encapsulated in the microcapsule. Therefore, the encapsulation rate of Example 10 is worse.

[0107] In addition, because polydopamine-modified silica affects the formation of microcapsules, for Example 11 and Example 12, if the addition time of polydopamine-modified silica is not appropriate, although Example 11 has excellent encapsulation efficiency, the resistance of Example 11 to rain erosion decreases significantly.

[0108] From the test results of Example 13 and Example 14, it can be seen that the effects of Example 13 and Example 14 are slightly better than that of Example 1, indicating that other adjuvants such as dispersants and emulsifiers can also help improve the performance of pesticides.

[0109] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A pesticide microcapsule suspension with degradable capsule wall, characterized in that: The raw materials include the following components by weight: 5-50 parts of original drug, 2-10 parts of isocyanate prepolymer, 3-5 parts of emulsifier, 2-4 parts of dispersant, 0.1-0.5 parts of curing agent, and 1.2-7.5 parts of other additives; The raw materials for preparing the isocyanate prepolymer include the following components: isocyanate and polyol, wherein the isocyanate is L-lysine ethyl diisocyanate, and the polyol is at least one of vegetable oil polyol, poly(ε-caprolactone) diol, and polylactic acid polyol; The raw materials for preparing the isocyanate prepolymer also include the following components: polydopamine-modified silica; the raw materials for the polydopamine-modified silica include the following components: nano-silicon dioxide, dopamine hydrochloride, and the amount of the nano-silicon dioxide and the dopamine hydrochloride is 1: (0.1-0.25) by mass ratio; The emulsifier includes at least one of ammonium salt of styrene-maleic anhydride copolymer, alkylbenzene sulfonate, and alkyl carboxylate; The dispersant is at least one of naphthalene sulfonates, alkylphenol polyoxyethylene ether formaldehyde condensates, tristyrylphenol polyoxyethylene ethers, naphthalene sulfonate formaldehyde condensates, and lignin sulfonates; The method for preparing the pesticide microcapsule suspension with degradable capsule wall comprises the following steps: The isocyanate and the polyol are mixed and reacted to obtain L-lysine ethyl ester diisocyanate prepolymer; The technical and L-lysine ethyl ester diisocyanate prepolymer are uniformly mixed to obtain an oil phase; adding an emulsifier and a dispersant into water and mixing to obtain an aqueous phase; The oil phase and the water phase are mixed and emulsified to obtain an emulsion, and a curing agent is added to the emulsion to react to obtain a microcapsule emulsion; Adding a viscosity regulator, a defoamer, a dispersant and an antifreeze agent to the microcapsule emulsion to obtain a pesticide microcapsule suspension; Nano-silicon dioxide and dopamine hydrochloride are reacted to prepare polydopamine-modified silicon dioxide; after turbidity occurs in the mixed reaction of isocyanate and polyol, the polydopamine-modified silicon dioxide is added into the mixed system of isocyanate and polyol.

2. The pesticide microcapsule suspension with degradable capsule wall according to claim 1, characterized in that: The other additives include antifreeze agents, defoaming agents and viscosity regulators.

3. The pesticide microcapsule suspension with degradable capsule wall according to claim 2, characterized in that: The viscosity modifier is at least one of xanthan gum, magnesium aluminum silicate, hydroxyethyl cellulose and white carbon black.

4. The pesticide microcapsule suspension with degradable capsule wall according to claim 1, characterized in that: The curing agent includes at least one of starch, cellulose, lignin, chitosan, sodium alginate and polylactic acid.

5. The pesticide microcapsule suspension with degradable capsule wall according to claim 1, characterized in that: The mass ratio of the isocyanate to the polydopamine-modified silica is 1:(0.012-0.021).

Images