JPH0240302A - Herbicide - Google Patents

Abstract

PURPOSE:To obtain a herbicide, capable of showing sustained release properties for a chemical, exhibiting effects thereof for a long period and preventing weeds from propagating, having high safety of the chemical and effective in killing weeds by enclosing a herbicidal active ingredient in cellular inorganic microcapsules. CONSTITUTION:A herbicide obtained by containing all the herbicides, such as ioxynil, asulam, atrazine, alloxydim and alachlor, in microcapsules (preferably having >=0.5mum particle diameter) made of a cellular inorganic material, e.g. silica or alkaline earth metal silicate, unreactive with the afore-mentioned herbicidal active ingredients. The above-mentioned encapsulated herbicide is used to provide herbicidal effects for a long period after spraying without a fear of environmental pollution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a herbicide that is effective in killing weeds and prevents their proliferation.

! Conventional Technology] Conventionally, weeding has been carried out manually, but in recent years, herbicides using chemicals have come into widespread use. This herbicide is commonly used in the form of an aqueous solution or emulsion.

[Problems to be Solved by the Invention] This type of herbicide preferably exhibits stable efficacy over a long period of time. However, conventional herbicides with such functions have a slow decomposition rate, so they may remain for a long time and be introduced into the food chain, and their use has been severely restricted in recent years. On the other hand, herbicides that are effective for a short period of time have low residual effectiveness, so it is necessary to use a larger amount than necessary each time or to spray the herbicides more frequently. However, using large amounts of herbicides is uneconomical, as there are concerns about the impact on non-target objects such as trees and crops, and increasing the number of sprayings requires a great deal of effort for the user. .

Therefore, an object of the present invention is to provide a herbicide that is highly safe and effective for a long period of time.

[Means for Solving the Problems] The above problems can be solved by encapsulating the herbicidal active ingredient in porous inorganic microcapsules and imparting sustained release properties to the drug.

[Effect] Since the present invention is a microcapsule type herbicide, as shown in Fig. 1, unlike conventional herbicides, the concentration of the drug at the point of action over time varies between the maximum permissible concentration and the minimum effective concentration. in range. Therefore, it remains effective for a long time. Furthermore, since inorganic porous microcapsules are used, problems due to the thickness of the wall film do not occur, unlike when the capsule wall is made of organic resin. In other words, if the wall film is thick, the elution of the drug will be excessively suppressed and the herbicidal performance will decrease, and if the wall film is thin,
There is no problem that the strength is weakened and sustained release properties are lost due to capsule destruction. As described above, the inorganic porous microcapsules containing the herbicidal active ingredient have a sustained release property because the elution rate of the drug is slow, and as a result, a long-life herbicide can be obtained.

[Specific structure of the invention] The present invention will be explained in more detail below.

In the present invention, all the drugs currently used as herbicides can be used as the herbicide active ingredients to be encapsulated in microcapsules.

For example, ioxinil, ajram, atrazine, alloxidim, alachlor, oxacyacin, glyphosate, clomethoxynil, dimetamethrine, biverovos dimethrine, tetrapion, trifluoraline, paraquat, pyrazolate, butachlorpromacin, peslozin, bentiocarb, triclopyr, pendimethalin, metripzim, molinate, ACN, CAT, CN
P.

Examples include DNBP, DPA, MCC, etc. These diffuse into the soil through the countless pores present in the microcapsule walls, and work to kill weeds or prevent them from breeding.

It is necessary to select a material for the microcapsule wall that does not react with these herbicidal active ingredients, and an inorganic material is preferable in terms of strength. Specific examples include silica and alkaline earth metal silicates.

There are various methods for encapsulating herbicidal active ingredients in microcapsules. For example, directly encapsulating drugs;
There is a method in which a pre-formed inorganic porous hollow body is evacuated, an aqueous solution or an organic solution in which a herbicidal active ingredient is dissolved is introduced, and the solvent is evaporated. For example, when using a herbicide that is insoluble in water or an organic solution, it can be used as a core material to prepare a W2O type emulsion and then microencapsulated by interfacial polymerization (precipitation). Furthermore, when using a water-soluble or oil-soluble herbicide, it can be encapsulated by preparing hollow microcapsules in advance and impregnating them or vacuuming them. For hollow microcapsules, the capsule wall is made using the same method as above without using a core material, and the reaction is stopped at an appropriate time, followed by washing and evaporation (solvent inside the capsule).
By this process, porous hollow capsules can be obtained.

The particle size of the microcapsules is preferably 0.5 μm or more.

If it is less than 0.5 μm, the total amount of herbicidal active ingredients contained therein will be too small, resulting in poor long-term performance.

Although there is no upper limit, it is usually 500 μm or less.

The pore diameter of the capsule is preferably 20 Å or more; if it is less than 20, the elution rate of the herbicidal active ingredient will be slow, and a large amount of the capsule-type herbicide will be required to exert the herbicidal effect, which is not practical.

[Example] Next, examples will be shown.

Sodium silicate aqueous solution (SiO□ equivalent 2 mol/β) 5
00ta! 1) was added to a 3% toluene solution of sorbitan monostearate 1) and shaken for 20 minutes with a shaker to obtain a W10 type emulsion. This was added to an aqueous ammonium sulfate solution (1 mol/7ml) while stirring and reacted for 30 minutes, followed by filtration, washing,
The porous hollow microcapsules (silica) used in Example 1 were obtained by drying at ctto° C. for 24 hours. By changing these concentrations and stirring speeds, capsules with various particle sizes and pore sizes can be obtained. Examples 2.3 and 5,
Furthermore, the microcapsules used in Example 4 were obtained by using an aqueous calcium chloride solution instead of an aqueous ammonium sulfate solution.

After evacuating various microcapsules in a Pelger, drop an alcoholic solution of Balaquat onto the capsules.
The capsule contained paraquat. When the content of baraquat was measured, it was about 50% by weight in Example-2.

This microcapsule-type herbicide was sprayed on leveled land where the grass on the surface of the ground had been cut, leaving the roots of the weeds intact, and the subsequent growth of weeds was measured. The growth status of weeds was evaluated by the total weight of weeds per unit area. The results are shown in Table 1.

For comparison, measurements were also taken when only paraquat was sprayed.

From the results in Table 1, in Examples 1 to 5, no weed growth was observed even after 180 days, indicating good herbicidal effects. Comparative Examples 1.2 did not exhibit sufficient long-term herbicidal properties because the capsule particle size or pore size was small.

These problems can be improved by increasing the amount of spraying, but this is not practical. Comparative Example 3 is an example in which paraquat was directly sprayed, but even though the total amount of paraquat sprayed was smaller than in Example 2, it had an adverse effect on trees and its long-term performance was poor. Furthermore, if the amount of paraquat sprayed is reduced as in Comparative Example 4, the effect on trees can be avoided, but the herbicidal performance is further reduced, so frequent spraying is required.

[Effects of the Invention] As described above, according to the present invention, by using an encapsulated herbicide, a long-term herbicidal effect can be obtained after spraying without worrying about environmental pollution.

[Brief explanation of the drawing]

FIG. 1 is a graph showing changes in drug concentration over time at point J. & errand questions

Claims (1)

[Claims] (1) A herbicide characterized by containing a herbicidal active ingredient in inorganic porous microcapsules.