JP3614773B2 - Coated sustained-release agrochemical granules - Google Patents

Description

【００５５】
（試験例１）：内核の溶出試験
参考例１〜６で得られた内核から放出される農薬活性成分（化合物１）の溶出率を以下に示す方法で測定した。
【００５６】
即ち、標準３度硬水２５ｍｌを入れた５０ｍｌ容の密栓付きサンプル管に、参考例１〜６で得られた内核を、それぞれ含有する農薬活性成分が全て溶出した際には、農薬活性成分（化合物１）の濃度が９２０ｐｐｍになる量に相当する量を投入して水中に沈めた。その状態で、２５℃下所定時間静置後、全量を濾別し、濾液中に溶解している農薬活性成分（化合物１）量をＨＰＬＣにて測定した。測定値より、下記式に基づき溶出率を計算し、結果を表２にまとめた。
【００５７】
溶出率＝（濾液中の農薬活性成分量／粒剤中の農薬活性成分量）×１００
表２に示す結果より明らかなように、本発明の徐放性農薬粒剤においてその内核に相当する参考例１〜６の造粒物（内核）は、含有する農薬活性成分（化合物１）を一週間から２ヶ月の範囲で任意の期間徐放化するとともに、ほぼ完全に放出させることが可能である。
【００５８】
【表２】

【００５９】
（実施例１〜１２）
表３に示す配合割合で、内核とする参考例１〜６の造粒物に、外層部を以下に示す方法により被覆形成して、実施例１〜１２の水稲の育苗箱用粒剤を得た。
【００６０】
まず、外層部の原料粉末として、含有させる農薬活性成分のプロベナゾール原体、無機系希釈担体としてクレー、第二の熱可塑性材料としてパラフィンワックス（日本精蝋（株）製、商品名パラフィンワックス１５０、融点６６℃）、ならびに、必要に応じて界面活性剤としてジアルキルスルホサクシネート（東邦化学工業（株）製、商品名Ｓｏｒｐｏｌ−５０５０）、または補助剤としてクエン酸を、一括してフローティングミキサーに入れ混合した。
【００６１】
次に、参考例１〜６にて得られた造粒物（内核）のいずれかを、加熱装置を装着したフローティングミキサーの中に入れ７０℃まで加熱しながら混合し、先の外層部原料粉末を定量的に添加していき、それぞれ目標の粒度分布、目開き１．０〜２．０ｍｍに相当する粒径を持つ粒子となるように被覆して、実施例１〜１２の水稲の育苗箱用粒剤を得た。なお、ここで得られた粒剤は、いずれも１ｇ当たりの粒子数はおよそ４００粒であった。
【００６２】
【表３】

【００６３】
（比較例１、２）
二種の農薬活性成分（化合物１（殺虫剤）とプロベナゾール（殺菌剤））とを共に造粒物中に含み、且つ被覆層を設けていない粒剤を得るために、表４に示す配合割合で、参考例１〜６の造粒物（内核）と同様の造粒方法で造粒物を調製した。得られた造粒物を、解砕後、篩別し、比較例１、２の粒剤を得た。
【００６４】
【表４】

【００６５】
（比較例３〜５）
表５に示すように、二種の農薬活性成分（化合物１（殺虫剤）とプロベナゾール（殺菌剤））とを共に配合し、参考例１〜６と同様の造粒方法で造粒物（内核）を得た。その後、実施例１〜１２と同様の手順で、農薬活性成分を全く含有していない外層部原料粉末を被覆して、比較例３〜５の粒剤を得た。
【００６６】
【表５】

【００６７】
（比較例６〜８）
表６に示すように、内核にプロベナゾール（殺菌剤））を配合し、参考例１〜６と同様の造粒方法で造粒物（内核）を得た。次いで、化合物１（殺虫剤）を入れて混合した外層部原料粉末を、実施例１〜１２と同様の手順で、造粒物（内核）表面に被覆して比較例６〜８の粒剤を得た。
【００６８】
【表６】

【００６９】
（比較例９）
表７に示す組成となるように、予め化合物１（殺虫剤）を溶解しておいたメタノール溶液を球状固体担体（東海工業（株）製、商品名 伊豆珪石粒、粒度０．３〜１ｍｍ）表面に吹き付けた後、５０℃乾燥器中に３時間静置してメタノールを除去し、徐放化されていない内核を得た。次いで、表７に示す組成の、プロベナゾール（殺菌剤）を入れて混合した外層部原料粉末を、実施例１〜１２と同様の方法で前記内核表面に被覆して、比較例９の粒剤を得た。
【００７０】
【表７】

【００７１】
（試験例２）：水稲の育苗箱用粒剤の溶出試験
上記の実施例１〜１２ならびに比較例１〜９で得られた粒剤について、各粒剤から放出される農薬活性成分の溶出率を測定した。
【００７２】
（１）化合物１（殺虫剤）の溶出率
実施例１〜１２ならびに比較例１〜９で得られた粒剤に含まれる二種の農薬活性成分のうち、各粒剤から放出される化合物１（殺虫剤）の溶出率を以下に示す方法で測定した。
【００７３】
即ち、標準３度硬水２５ｍｌを入れた５０ｍｌ容の密栓付きサンプル管に、実施例および比較例で得られた各粒剤を、それぞれ含有する化合物１（殺虫剤）が全て溶出した際には、化合物１（殺虫剤）の濃度が９２０ｐｐｍになる量に相当する量を投入して水中に沈めた。その状態で、２５℃下所定時間静置後、全量を濾別し、濾液中に溶解している化合物１（殺虫剤）量をＨＰＬＣにて測定した。測定値より、下記式に基づき溶出率を計算し、結果を表８にまとめた。
【００７４】
溶出率＝（濾液中の殺虫剤量／粒剤中の殺虫剤量）×１００
【００７５】
【表８】

【００７６】
表８に示す結果より明らかなように、実施例の粒剤では、内核に含有している殺虫活性成分を約１ヶ月から３ヶ月間、持続して放出させることが可能であり、しかも、ほぼ完全に含有されている殺虫活性成分の全量が放出された。これに対して、被覆層を設けていない比較例１、２、また、内核でなく、外層部中に化合物１を含んでいる比較例６〜８、あるいは、徐放化技術を施していない内核に化合物１を含有させている比較例９では、いずれも徐放化されず、ほぼ１〜３日の間に、１００％近い溶出率に達していた。
【００７７】
（２）プロベナゾール（殺菌剤）の溶出率
実施例１〜１２ならびに比較例１〜９で得られた粒剤に含まれる二種の農薬活性成分のうち、各粒剤から放出されるプロベナゾール（殺菌剤）の溶出率を以下に示す方法で測定した。
【００７８】
即ち、イオン交換水１０００ｍｌを入れた１０００ｍｌ容の密栓付き三角フラスコに、実施例および比較例で得られた各粒剤を、それぞれ含有するプロベナゾール（殺菌剤）が全て溶出した際には、プロベナゾール（殺菌剤）の濃度が３０ｐｐｍになる量に相当する量を投入して水中に沈めた。その状態で、２５℃下静置した。次いで、所定時間毎に水深５ｃｍの深さより、１ｍｌを採水し、その採水サンプル中の殺菌剤濃度をＨＰＬＣにて測定した。供試粒剤中の殺菌剤全量が三角フラスコ中の水１０００ｍｌに溶出したときの濃度は、３０ｐｐｍに達する条件であり、その殺菌剤濃度測定値を３０ｐｐｍで除して、溶出率とした。結果を、表９にまとめた。
【００７９】
【表９】

【００８０】
表９に示す結果より明らかなように、実施例の各粒剤は、約３ヶ月間一定の殺菌剤を放出させることが可能であり、しかも、外層部に含有している殺菌剤の全量がほぼ完全に放出されていた。これに対して、内核に殺菌剤を含有している比較例３〜８の粒剤では、約２ヶ月経過しても、含有量の一部しか溶出しておらず、従って、極端に低い溶出率となっていた。
【００８１】
【発明の効果】
本発明の被覆型徐放性農薬粒剤においては、水溶解度が極端に異なる二種以上の農薬活性成分を含有する際、特に一方の水溶解度が１０００ｐｐｍ以上である場合においても、それら二種以上の農薬活性成分をそれぞれ徐放化することができ、例えば、水稲の育苗箱用粒剤に適する農薬混合粒剤が得られる。また、本発明の被覆型徐放性農薬粒剤では、含有する農薬活性成分二種以上ともに、その含有量の全量をほぼ完全に放出することができるため、所望の期間中に圃場に徐々に散布すべき農薬活性成分が溶出を終えず、その一部が粒剤中に残留する恐れもない。さらには、本発明の被覆型徐放性農薬粒剤は、その製造に際して、内核を、その表面を樹脂で被覆した被覆粒とする必要がなく、この樹脂被覆後に設ける乾燥工程など、余剰な工程を省くことができるため、二層構造の剤型を採用しつつ、その製造コストを低く抑えることができる利点も有する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sustained-release agrochemical granule that contains two or more different types of agrochemical active ingredients and is used to elute and supply each agrochemical active ingredient to an aqueous medium, and a method for producing the same. Specifically, for example, when it is applied to a seedling box used for raising rice seedlings and then planted in rice, it is transferred to the rice field together with the stored seedlings, and then a plurality of kinds of pesticide activities contained in the granules for a certain period of time. The present invention relates to a sustained-release agrochemical granule that can be suitably used as a pesticide granule for a nursery box in which components are continuously released at individual elution rates and a method for producing the same.
[0002]
[Prior art]
In recent years, paddy fields have been rapidly scaled up and mechanized to reduce the cost of rice cultivation. In response to this, technological innovation related to the spraying method of agricultural chemicals has progressed, and various labor-saving preparations and spraying methods have been studied. As an example, development of a seedling box treatment method in which an agrochemical composition is applied to a paddy rice seedling box before planting rice is being promoted. The greatest advantage of the seedling box treatment method in paddy rice cultivation is that the seedlings can be treated with agricultural chemicals at the same time as rice planting. Moreover, even after being transferred to the rice field together with the seedlings, pest control can be achieved over a long period of time after rice planting by slow release of the pesticidal active ingredient contained in the agricultural chemical preparation to be used. Because of this advantage, the seedling box treatment method is an ideal labor-saving application method for pesticides that need to be sprayed during the rice planting season.
[0003]
On the other hand, in recent years, more than two kinds of pesticidal active ingredients, for example, a preparation containing only one pesticidal active ingredient, Insecticide When Fungicide Thus, there is a demand for an agrochemical formulation that enables simultaneous control by a single treatment. That is, a mixed preparation having two or more pesticidal active ingredients that exhibit different actions, and more specifically, 30 to 60 days that need pest control during the rice cultivation period, or more in some cases There is a need for a mixed preparation that releases a pesticidal active ingredient continuously over a long period of time.
[0004]
As an example of sustained release of two or more kinds of pesticidal active ingredients, Japanese Patent Application Laid-Open No. 2000-44404 discloses that the inner core particles containing pesticidal active ingredients that require sustained release are coated with a resin. There is disclosed a mixed preparation having a structure in which an outer layer portion containing another pesticidal active ingredient is further provided outside the coated grain after the coated grain is formed. The important features in the composition of the mixed preparation described here are that (1) it is essential to coat the surface of the inner core particle with a resin, and (2) the outer layer part is not necessarily released gradually. In addition, (3) there is no particular consideration for the difference in water solubility between the two types of active ingredients of the agricultural chemicals contained mainly in the inner core particle and the outer layer part.
[0005]
Referring to Japanese Patent Application Laid-Open No. 2000-44404 in more detail, with respect to the effect of coating the inner core particles with resin, in Table 4 showing the results of Test Example 1 (dissolution test), Examples 2 to 4 and Comparative Examples When the results of 2 to 4 are compared, the elution of the compound contained in the inner core particles is suppressed in Examples 2 to 4 in which the inner core particles are coated with the resin, compared to Comparative Examples 2 to 4 in which the inner core particles are not coated. From this, it is clear that the provision of the resin coating has a significant contribution to the sustained release of the pesticidal active ingredient contained in the inner core particles (the elution is controlled). In addition, once the inner core particles are prepared, a process for coating the surface with a resin is provided, so of course, the number of granule manufacturing steps is increased accordingly, and the operation cost is increased accordingly. To do.
[0006]
Moreover, about the point by which slow release of an outer layer part is not essential, Examples 1-3 in which the elution characteristic is verified in Test Example 1 (elution test) utilize an inorganic solid support for the outer layer part Therefore, there is no room for discussion because it shows a case where it is molded, and in particular, the case where the sustained release treatment is not performed. However, Table 4 shows the result that benfuracarb, an agrochemical active ingredient contained in the outer layer part, gradually elutes in water. This slow elution has a water solubility of benfuracarb at 20 ° C. of 80 ppm, and benfuracarb itself is a compound that is relatively difficult to dissolve in water. Is understood to reflect that. In addition, the test period is a relatively short period of 10 days. Within this period, the inorganic solid carrier molding layer constituting the outer layer portion is slightly disintegrated, and the sustained release treatment is not necessarily performed. Even if it is not applied, it is presumed that contact with the aqueous medium is suppressed.
[0007]
With respect to the two types of agrochemical active ingredients to be contained in the inner core particle and the outer layer part, in this Japanese Patent Application Laid-Open No. 2000-44404, the water solubility of the agrochemical active ingredient to be used is not particularly taken into account. No consideration is given to the difference. Incidentally, in the mixed preparation shown in the Examples, the water solubility of benfuracarb contained in the outer layer part is 80 ppm as described above, and the water solubility of propenazole contained in the inner core particle at 20 ° C. is 150 ppm, The difference is only 70 ppm, which is not very different.
[0008]
In addition, as disclosed in Japanese Patent Application Laid-Open No. 2000-26206, it is already known to use a wax for sustained release of an agrochemical active ingredient having high water solubility. However, by using a sustained release method using a hydrophobic substance such as wax, the same is applied to two or more pesticidal active ingredients, particularly two pesticidal active ingredients having extremely different solubility in water. When trying to release slowly using a wax, if the wax with the optimal release rate of one pesticidal active ingredient is selected, the release rate of the other pesticidal active ingredient becomes extremely fast, or conversely, Either slow, or both, it was difficult to achieve a moderately slow release rate. That is, as far as the present inventors know, as an agrochemical formulation containing two or more kinds of pesticidal active ingredients having extremely different water solubility in one granule and simultaneously releasing the two or more pesticidal active ingredients simultaneously, A suitable dosage form is not known, and there is no report of an example in which two or more kinds of waxes are used for sustained release of different pesticidal active ingredients.
[0009]
[Problems to be solved by the invention]
As described above, two or more kinds of pesticidal active ingredients are contained, and at least one of the pesticidal active ingredients has been proposed for sustained release, but the pesticidal active ingredients having extremely different water solubility are proposed. In the agrochemical formulation containing at least two kinds, if both of them can be simultaneously released so as to be released at individual elution rates, for example, it is suitable as an agrochemical granule for use in a rice seedling box treatment method. So far, there has been no proposal of a dosage form that satisfies this demand.
[0010]
The present invention solves the above-mentioned problems, and an object of the present invention is, for example, two different types or more different in one agrochemical formulation desired for agrochemical granule used in a rice seedling box treatment method. A novel dosage form containing pesticidal active ingredients with extremely different water solubility, and each pesticidal active ingredient with extremely different water solubilities being released simultaneously at a desired dissolution rate It is an object of the present invention to provide a sustained release agrochemical granule and an efficient production method thereof.
[0011]
[Means for Solving the Problems]
As a result of diligent research and examination to solve the above-mentioned problems, the inventors of the present invention have high water solubility when each of two or more agricultural chemical active ingredients having extremely different water solubility is released slowly. The pesticidal active ingredient is dispersed in a wax matrix and formed into a granulated product, which is used as the inner core. On the other hand, the pesticidal active ingredient having a low water solubility is mixed with another wax having a melting point lower than that of the inner core and mixed with the surface of the inner core. It was considered to form a granule with a double structure by coating the outer layer with the outer layer.
[0012]
The present inventors have found that by adopting such a configuration, both the pesticidal active ingredient having a high water solubility in the inner core and the pesticidal active ingredient having a low water solubility in the outer layer are gradually released.
[0013]
More specifically, the agrochemical granule of the present invention is prepared as follows.
[0014]
First, at least one kind of highly water-soluble pesticidal active ingredient, inorganic diluent carrier and first thermoplastic material that is hardly soluble in water used as a wax component are heated, mixed and granulated, A granulated product that is a uniformly dispersed inner core is prepared.
[0015]
Next, at least one kind of agrochemical active ingredient having low water solubility, an inorganic diluent carrier, and a second thermoplastic material having a melting point lower than that of the first thermoplastic material and hardly soluble in water are used as the first thermoplastic material. The double-structured granule of the present invention is obtained by coating a mixture in which each component obtained by heating and mixing at a temperature not exceeding the melting point of the material is uniformly dispersed on the surface of the granulated material as the inner core and then cooling it. Is made.
[0016]
According to the study of the present inventors, in the granule of the present invention, by adopting the dual structure prepared as described above, the agrochemical active ingredient contained in the inner core has high water solubility. Nevertheless, sufficient sustained release is achieved by the action of the first thermoplastic material, and the other agrochemical active ingredients contained in the outer layer portion are added to the second thermoplasticity in addition to the poor water solubility of the agrochemical active ingredient itself. It has been found that sufficient sustained release is achieved by the action of the materials, and eventually two or more kinds of agrochemical active ingredients having different water solubility in one granule can be appropriately sustainedly released. The inventors of the present invention have completed the present invention on the basis of the knowledge acquired through these studies and examinations.
[0017]
That is, the sustained release agricultural chemical granules of the present invention are:
A sustained release agrochemical granule used to continuously elute and supply agrochemical active ingredients to an aqueous medium,
The granule has a configuration of a coated granule composed of an inner core and an outer layer portion covering the surface thereof,
The inner core is a granulated product comprising at least one agrochemical active ingredient having a water solubility at 20 ° C. of 1000 ppm or more and 10% or less, an inorganic diluent carrier, and a first thermoplastic material that is hardly soluble in water. Yes,
The outer layer portion has a melting point lower than that of the first thermoplastic material contained in the inner core, at least one agrochemical active ingredient having a water solubility of 0.01 to 500 ppm at 20 ° C., an inorganic diluent carrier, and It is a coating layer composed of a second thermoplastic material which is a different material and hardly soluble in water,
With such a constitution of the coated granule, the sustained release pesticide granule is characterized in that the pesticidal active ingredient contained in the inner core and the pesticidal active ingredient contained in the outer layer part are each controlled for sustained release. is there.
[0018]
In the sustained-release agrochemical granule of the present invention, the outer layer portion may further contain a surfactant. Further, for example, the first thermoplastic material that is hardly soluble in water contained in the inner core may be a montanic acid wax and / or a montanic acid ester wax. On the other hand, the second thermoplastic material that is hardly soluble in water contained in the outer layer portion is preferably a paraffin wax.
[0019]
In the sustained-release agrochemical granule of the present invention, for example, the agrochemical active ingredient contained in the inner core is (RS) -1-methyl-2-nitro-3- (tetrahydro-3-furylmethyl) guanidine,
A configuration in which the agrochemical active ingredient contained in the outer layer portion is probenazole can be selected.
[0020]
In addition, the method for producing the sustained-release agrochemical granule of the present invention comprises:
A method for producing a sustained-release agrochemical granule having the above-described structure,
When forming a coating layer that is an outer layer portion on the surface of the granulated product that becomes the inner core,
The second thermoplastic material constituting the coating layer is heated and melted to achieve a coating on the surface of the granulated material, and heated to a temperature that does not reach the melting point of the first thermoplastic material contained in the inner core. It is the manufacturing method of the granule characterized by doing.
[0021]
In the two-layer structure of the sustained-release agrochemical granule of the present invention, the term “inner core” is used to mean the portion that becomes the agrochemical nucleus in the central part inside the granule, and the term “outer layer part” is used as the surface of the granule. , Used to mean the portion covering the outer periphery of the inner core.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Below, the sustained release agricultural chemical granules of the present invention will be described in more detail.
[0023]
The sustained-release agrochemical granule of the present invention is, for example, a mixed preparation containing, in one granule, an agrochemical active ingredient having at least two kinds of action in a granule for a seedling box used for a seedling box treatment of paddy rice In this case, the dosage form can be suitably used. In other words, after spraying as a seedling box granule, when two or more kinds of pesticide active ingredients with different actions that need to be gradually eluted and maintained at a desired concentration are supplied. By using the sustained-release pesticidal granules of the present invention having a two-layer structure, the release of one pesticidal active ingredient from the outer layer for a certain period of time and the other pesticidal active ingredient from the inner core over a long period of time Release can be sustained. Therefore, the elution control achieved with the sustained-release agricultural chemical granules of the present invention indicates that different types of agricultural chemical active ingredients contained in the outer layer and the inner core are simultaneously and gradually eluted.
[0024]
The sustained-release agrochemical granule of the present invention takes a two-layer structure composed of an inner core and an outer layer portion, and contains two or more pesticide active ingredients with extremely different water solubility. The inner core contains a pesticide active ingredient with high water solubility, and the outer layer contains a pesticide active ingredient with low water solubility. According to the water solubility of the pesticide active ingredient, It is divided. Specifically, the agrochemical active ingredient contained in the inner core is selected so that the water solubility at 20 ° C. is 1000 ppm or more and 10% or less, and conversely, the agrochemical active ingredient contained in the outer layer portion has an aqueous solubility at 20 ° C. The combination is limited to 0.01 to 500 ppm and has a remarkable difference in water solubility between the two.
[0025]
At that time, the pesticidal active ingredient contained in the inner core, which has a very high water solubility, has a form dispersed in a wax matrix in order to control its dissolution and release rate and to give sufficient sustained release, As the wax component for the matrix, the first thermoplastic material that is hardly soluble in water is used. As a result of forming the first thermoplastic material, which is hardly soluble in water, as a matrix, contact between the aqueous medium and the agrochemical active ingredient is suppressed. In addition, although the outer layer portion is also composed of a second thermoplastic material that is sparingly soluble in other types of water, it also functions as a coating layer using a wax as a binder, and as a result, the agrochemical active ingredient further contained in the inner core Sustained release of is increased. On the other hand, the pesticidal active ingredient with low water solubility contained in the outer layer part is dispersed in the wax matrix using the second thermoplastic material which is hardly soluble in water, and the low water solubility is combined. Thus, the dissolution and release rate is controlled, and a desired sustained release property is imparted.
[0026]
Thus, in the sustained-release agrochemical granule of the present invention, the existence location in the two-layer structure composed of the inner core and the outer layer portion, depending on the difference in water solubility, for the plural types of agrochemical active ingredients to be contained In addition, the type of wax to be used is differentiated according to its water solubility so that the wax matrix is optimal for achieving the desired sustained release. At that time, since the release rate also depends on the particle diameter of the granule (ratio of surface area to volume), for the purpose of setting the desired inner core particle diameter and the entire particle diameter covering the outer layer part to a predetermined value, In addition to each pesticidal active ingredient, an inorganic diluent carrier is added, and the pesticidal active ingredient and inorganic diluent carrier are uniformly mixed with each other and dispersed in a wax matrix composed of a thermoplastic material. The content of the pesticidal active ingredient per volume is adjusted to an appropriate range.
[0027]
As described above, the sustained-release agrochemical granule of the present invention has a two-layer structure composed of an inner core and an outer layer part, each of which is a wax matrix using different thermoplastic materials. And a shape that is clearly divided into an outer layer portion. In order to easily produce the structure, once using the first thermoplastic material as the inner core, after heating and mixing, a granulated product molded to the desired particle size is prepared, and this surface becomes the outer layer part The coating composition is coated, the second thermoplastic material is melted under heating to form a liquid, and then the composition is suitable for the production method of coating on the granulated product. Specifically, in the step of coating the outer layer portion, when used in the heating environment, the outer layer portion is used in order to avoid remelting of the first thermoplastic material that maintains the shape of the granulated material serving as the inner core. The melting point of the second thermoplastic material is selected to be lower than the melting point of the first thermoplastic material. Therefore, although the heating condition in the step of forming the outer layer portion is equal to or higher than the melting point of the second thermoplastic material, the first thermoplastic material is prevented from causing melting of the first thermoplastic material. Select a temperature that does not exceed the melting point of.
[0028]
Thus, in the sustained-release agrochemical granule of the present invention, as a result of subjecting the inner core and the outer layer portion to a sustained release treatment using different thermoplastic materials, for example, pathogens that require different control periods, Even when two or more pesticidal active ingredients having a controlling action against pests are contained, a sustained release function in which the release of these two or more pesticidal active ingredients individually can be secured.
[0029]
Furthermore, the method for producing the sustained-release agricultural chemical granules of the present invention will be described more specifically. First, the pesticidal active ingredient and the inorganic diluent carrier are used as a first heat that is sparingly soluble in water so that the elution of the pesticidal active ingredient having a water solubility at 20 ° C. of 1000 ppm to 10% is gradually released. Using a plastic material, the mixture is heated to a temperature equal to or higher than the melting point of the first thermoplastic material, and the uniformly mixed composition is formed into a desired shape and particle size, cooled, and the granulated product for the inner core is formed. Prepare. Next, the surface of the granule for inner core is uniformly mixed with an agrochemical active ingredient having an aqueous solubility of 0.01 to 500 ppm at 20 ° C. and an inorganic diluent carrier together with a second thermoplastic material that is hardly soluble in water. A two-layered granule having an inner core and an outer layer portion provided on the surface thereof is obtained by coating the composition while being heated to a temperature equal to or higher than the melting point of the second thermoplastic material. Can do. At this time, the melting point of the second thermoplastic material is selected so that the melting point of the second thermoplastic material is lower than the melting point of the first thermoplastic material. It becomes possible to set the temperature so as not to reach the melting point of the thermoplastic material. The state in which the elution of the agrochemical active ingredient in the inner core is sustained is the release of the agrochemical active ingredient into water by heating and melting the first thermoplastic material, which is sparingly soluble in water, into a matrix. It means that it is a pesticide granule that controls
[0030]
That is, the sustained-release agrochemical granule of the present invention can be specifically produced by the following steps.
Process {circle around (1)} First, a mixer equipped with a heating device for an agrochemical active ingredient with high water solubility, a water solubility at 20 ° C. in the range of 1000 ppm to 10%, and an inorganic diluent carrier, and the first thermoplastic material Mix by heating (for example, a floating mixer). At this time, the heating temperature is not lower than the melting temperature of the first thermoplastic material and does not reach the melting point of the pesticidal active ingredient contained therein.
Step {circle around (2)} After heating and mixing, the obtained uniform mixture is granulated by a granulator equipped with a heating device. The type of granulator is appropriately selected in consideration of the shape of the intended granulated product, the particle diameter, and the like. Specifically, when a cylindrical molded product is obtained, an extrusion granulator equipped with a screen suitable for the target particle size is exemplified, and when a spherical molded product is obtained, a rolling granulator is exemplified. . The granulation temperature is preferably set to a temperature not lower than the temperature at which the first thermoplastic material to be used is melted and not reaching the melting point of the agrochemical active ingredient contained therein.
Step {circle around (3)} The obtained granulated product often adheres to each other, and is crushed and classified with a sieve if necessary, and the sustained-release granulated product having a desired shape and particle diameter ( Inner core).
Step (4) Unlike the pesticidal active ingredient having a high water solubility contained in the inner core, the pesticidal active ingredient having a low water solubility in the range of 0.01 to 500 ppm at 20 ° C. and an inorganic diluent carrier, A second thermoplastic material that is different from the first thermoplastic material contained in the inner core and has a lower melting point than the first thermoplastic material and is sparingly soluble in water, and optionally a surfactant and The auxiliary agent is mixed together with a mixer (for example, a floating mixer) to obtain a raw material powder for the outer layer portion.
Process (5) Put the inner core prepared in process (3) into a mixer equipped with a heating device (eg floating mixer, rolling granulator, cooler mixer, drum mixer, malmerizer, etc.) and mix while heating. Then, the outer layer raw material powder prepared in the step (4) is quantitatively charged and coated so as to be particles having a target particle size distribution. At that time, the outer layer part to be coated is set to a temperature at which the second thermoplastic material containing the heating temperature is dissolved, so that the melted second thermoplastic material serves as a binder and the agrochemical active ingredient has low water solubility. A coating layer in which the inorganic diluent is uniformly dispersed is formed, and the coated sustained-release agrochemical granule of the present invention is obtained. In order to avoid adhesion and fusion of inner core particles due to softening / melting of the first thermoplastic material in the inner core during the heating / coating process, and further to avoid adhesion / crimping of the inner core to the inner wall of the mixing tank, It is essential that the heating temperature is equal to or higher than the temperature at which the second thermoplastic material used for the outer layer is melted and does not reach the melting point of the first thermoplastic material used for the inner core.
[0031]
In the coated sustained-release agrochemical granule of the present invention having the structural features described above, the composition ratio of each composition constituting the outer layer portion and the inner core is not particularly limited, and the outer layer portion and the inner core are respectively limited. The dissolution rate of each at least one pesticidal active ingredient to be contained, the metabolic degradation rate in the plant body and the absorption rate into the plant body, and further, in the field where plant seedlings are replanted, The concentration range to be maintained, for example, the control effect expression concentration, the period during which the concentration should be maintained, and the like may be appropriately determined. At that time, generally, the weight of each at least one pesticidal active ingredient to be contained in the outer layer portion and the inner core per one granule is subtotaled, and the ratio of the subtotal weight is determined as inner core: outer layer portion = 1. It is good to set it as the range of 15-15: 1. The coated sustained-release agrochemical granule of the present invention is not limited in its outer size and dosage form as long as it is a solid agent composed of an outer layer part and an inner core. For example, a normal granule type, a pill Any shape such as a type and a tablet type may be used. Moreover, when taking the said dosage form, the magnitude | size can also be suitably selected according to a usage form, For example, if a cylindrical shape and a spherical diameter are in the range of 0.1-3 mm, it will not specifically limit. Specifically, in the coated sustained-release agrochemical granule of the present invention, the particle size is appropriately selected according to the form to be sprayed, and for example, it is applied to a rice seedling box granule. In this case, it is preferable to select a screen opening for adjusting the particle diameter and the outer shape in the range of 0.3 to 3 mm. In addition, it is preferable to select the columnar length within a range that does not become excessively long according to the diameter. For example, if the columnar diameter is within a range of 0.1 to 3 mm, the length Is preferably selected in the range of 0.1 to 10 mm.
[0032]
In the coated sustained-release agrochemical granule of the present invention, for example, when taking a spherical shape, the diameter ratio of the inner core part to the outer layer part is not particularly limited, and is generally in a range not exceeding 1: 3. You can choose. In general, the elution of the contained pesticidal active ingredient is accelerated as the particle size of the granule decreases and the granule surface area per unit content of the pesticidal active ingredient increases. In sustained-release agrochemical granules, the inner core and outer layer are each made of a thermoplastic material that is sparingly soluble in different waters. As long as the diameter ratio of the outer layer portion is within the above range, desired elution characteristics can be achieved.
[0033]
Specifically, the inner core part and the outer layer part each have a constitution containing an inorganic diluent carrier in addition to the agricultural chemical active ingredient, thereby adjusting the amount of the agricultural chemical active ingredient contained per unit volume in a wide range. Therefore, the granule surface area per unit content of the pesticidal active ingredient can be adjusted within a certain range. At that time, in order to dilute each pesticidal active ingredient uniformly with an inorganic diluent carrier in each of the inner core part and the outer layer part, a method in which each pesticidal active ingredient and inorganic diluent carrier are mixed together in powder form. It is more preferable to use
[0034]
In the coated sustained-release agrochemical granule of the present invention, different types of agrochemical active ingredients to be contained in the inner core and the outer layer, respectively, generally include pesticides that can be used for target plants, for example, paddy rice. Among the active ingredients, at least one or more pesticidal active ingredients having high water solubility in the range of 1000 ppm to 10% in water solubility at 20 ° C., and water solubility in the range of 0.01 to 500 ppm water solubility at 20 ° C. It is preferable to use a compound that has biocidal activity and is used for agricultural and horticultural use, at least one of the low pesticidal active ingredients. For example, preferably, for the compound having biocidal activity, a combination of insecticide and fungicide is selected, but a combination of insecticides whose action mechanisms are different from each other, or a combination of fungicides, Selecting a combination of drugs that differ in their effective control period is not excluded from the preferred combination. In addition, the content of these pesticidal active ingredients in the coated sustained-release pesticidal granules is not distinguished depending on whether the containing site is the inner core or the outer layer part, and in each part, usually 0.01 mass % To 50% by mass, preferably 0.5% to 30% by mass, but is not particularly limited. That is, the content of each pesticidal active ingredient contained per granule is determined by the physical properties of the active ingredient and the application scene, and depending on its application form, for example, the form of application as a seedling box granule, What is necessary is just to select content so that the quantity spread | dispersed per hit may satisfy | fill the required processing amount per 10 are.
[0035]
In the coated sustained-release agrochemical granule of the present invention, in order to obtain a mixed granule in which two or more kinds of agrochemical active ingredients having significantly different water solubility are individually released, the agrochemical active ingredient contained in the inner core It is essential that the water solubility at 20 ° C. is significantly higher than the water solubility of the agrochemical active ingredient contained in the outer layer portion. That is, the water solubility at 20 ° C. of the pesticidal active ingredient to be contained in the inner core is selected in the range of at least 1000 ppm to 10%, preferably 5000 ppm to 10%, more preferably 10,000 ppm to 10%, while the outer layer portion. The water solubility of the pesticidal active ingredient to be contained in 20 ° C. is at least 0.01 to 500 ppm, preferably 0.1 to 300 ppm, more preferably 0.5 to 200 ppm. It is preferred to select such that there are orders of magnitude differences between them.
[0036]
In addition, when the melting point of the pesticidal active ingredient to be contained in the inner core is the same as or lower than the melting point of the first thermoplastic material used in the inner core, in the step of producing the sustained-release pesticidal granules of the present invention, granulation for the inner core When the product is prepared and heated to melt the first thermoplastic material, the pesticidal active ingredient mixed therein is also melted. In this state, there is a possibility that they are not uniformly mixed with each other in a liquid state, and even if they are uniformly mixed, there is a possibility that the agrochemical active ingredient is localized and not uniformly dispersed when solidified thereafter. In such a case, in the inner core, the form in which the pesticidal active ingredient is uniformly dispersed in the wax matrix of the first thermoplastic material together with the added inorganic diluent carrier is not achieved, and the expected slowdown is not achieved. There is great concern that liberalization will not be achieved. In order to eliminate the concern, it is desirable that the melting point of the pesticidal active ingredient contained in the inner core is higher than the melting point of the first thermoplastic material to be used, and preferably one having a melting point of 100 ° C. or higher is used. The pesticide active ingredient contained in the inner core is not melted by such selection, but the first thermoplastic material is heated to a temperature at which it softens and melts, for example, a powdery pesticide active ingredient and an inorganic diluent carrier Is preferably uniformly mixed and dispersed in the first thermoplastic material. Similarly, when the melting point of the pesticidal active ingredient contained in the outer layer part is the same as or lower than the melting point of the second thermoplastic material used in the outer layer part, the second thermoplastic material is melted in the step of coating the outer layer part. Therefore, when heated, the pesticidal active ingredient mixed with it will also melt. In that case, there is a concern that the same problem occurs. In avoiding this in advance, the melting point of the agrochemical active ingredient contained in the outer layer portion is at least higher than the melting point of the second thermoplastic material to be used, and preferably higher than that of the first thermoplastic material. It is desirable that the melting point is higher than the melting point. Preferably, a melting point of 100 ° C. or higher is used.
[0037]
Specific examples of the pesticidal active ingredient satisfying the above conditions include the following. As an agrochemical active ingredient to be contained in the inner core, for example, in insecticides, thiocyclam (125 to 128 ° C., about 8%), acetamiprid (101 to 103...) Having melting points and water solubility at 20 ° C. shown in parentheses, respectively. 3 ° C., 4200 ppm), thiamethoxam (139.1 ° C., 4100 ppm), or compound (RS) -1-methyl-2-nitro-3- (tetrahydro-3-furylmethyl) disclosed in JP-A-7-179448 ) Guanidine (about 105 ° C., 54000 ppm), and examples of the bactericidal agent include pyrokilone (112 ° C., 4000 ppm), blasticidin S (235 ° C., 3%), and the like.
[0038]
On the other hand, as an agrochemical active ingredient to be contained in the outer layer portion, for example, insecticides, NAC (142 ° C., about 100 ppm), Bendiocarb (124. 6-128.7 ° C., 40 ppm), clothianidin (176-178 ° C., 270 ppm), pymetrozine (234.4 ° C., 270 ppm), fipronil (about 200 ° C., 1.9 ppm), buprofezin (about 105 ° C., 0.9 ppm) ), Tebufenozide (191 ° C., 0.83 ppm), and as fungicides, thiuram (155 ° C., 30 ppm), iprodione (136 ° C., 13 ppm), flutolanil (102 ° C., 9.6 ppm), tifluzamide ( About 178 ° C., 1.59 ppm), carpropamide (147-149 ° C., .6 ppm), azoxystrobin (about 118 ° C., 10 ppm), probenazole (138 ° C., 150 ppm), diclosimet (about 150 ° C., 5 ppm), oxolinic acid (310 ° C., 3.2 ppm), teclophthalam (198 ° C., 14 ppm) ), Ferrimzone (175 ° C., 162 ppm), dichromedin (250-253.5 ° C., 0.74 ppm), captan (178 ° C., 3.3 ppm), and the like. Among them, the combination in which the insecticide (RS) -1-methyl-2-nitro-3- (tetrahydro-3-furylmethyl) guanidine is arranged in the inner core and the fungicide probenazole is arranged in the outer layer portion is the slowness of the present invention. When preparing a releasable agrochemical granule as a granule for a seedling box, it is one of suitable combinations.
[0039]
The first thermoplastic material for the inner core used in the sustained-release agrochemical granule of the present invention has a water solubility at 20 ° C. of less than 0.5% and is insoluble or hardly soluble in water at room temperature. It is preferable to use an organic substance having a melting point of 70 ° C to 110 ° C, preferably 72 ° C to 100 ° C, more preferably 74 ° C to 98 ° C. For example, plant waxes such as candelilla wax, sugarken wax, rice wax, mineral waxes such as montanic acid wax, ozokerite, and ceresin, petroleum waxes such as microcrystalline wax and petrolatum, and synthetic hydrocarbons such as Fischer-Tropsch wax Modified waxes such as montanic acid wax derivatives, paraffin wax derivatives, microcrystalline wax derivatives, hydrogenated waxes of hardened castor oil, hardened castor oil derivatives, 12-hydroxystearic acid, stearamide, phthalimide anhydride, Examples include fatty acids having a chlorinated hydrocarbon group, acid amides, esters, and ketones. Among them, an acid value of 10 mgKOH / g or more is preferable as an acid value obtained by titration with an alkali in accordance with a test method defined in ASTM D1386. For example, sugarken wax (melting point: 75 ° C., acid value: about 21 mg KOH / g) and montanic acid wax (manufactured by BASF, trade name Luwax S, melting point: 75-85 ° C., acid value: 135-160 mg KOH / g), Montanic acid ester wax (BASF, trade name Luwax E, melting point: 75 to 85 ° C., acid value: 10 to 25 mg KOH / g) and the like are imparted with a sustained release property, but are contained in the inner core Can be released almost 100%, which is particularly preferable. These waxes and thermoplastic materials may be used alone or in combination of two or more. The total amount of the first thermoplastic material used is usually 5% by mass or more, preferably 10% by mass or more, with respect to the total weight of the composition of the inner core constituting the sustained-release agricultural chemical granules of the present invention. However, it can be appropriately determined in consideration of the amount of the pesticidal active ingredient to be added and the physical properties and amount of the inorganic diluent carrier. Preferably, from the economical viewpoint, the upper limit of the amount of the first thermoplastic material added is preferably 20% by mass.
[0040]
The inorganic diluent carrier for the inner core used in the sustained-release agrochemical granule of the present invention is not particularly limited as long as it shows at least almost no water solubility. For example, clay, quartzite, talc, bentonite, carbonic acid Calcium, pumice, diatomaceous earth, vermiculite, pearlite, attapulgite, amorphous hydrous silicic acid, commonly known as white carbon, etc., and commonly used in agricultural powders and granules, so-called extenders and carriers are used in combination with one or more it can.
[0041]
Further, in the sustained-release agrochemical granule of the present invention, the inner core contains an antioxidant, an ultraviolet absorber, an antistatic agent, etc., as long as the purpose and effect of the present invention are not impaired, in addition to the inorganic diluent carrier. Various additives can also be added to form granules. Examples of antioxidants include hindered phenol antioxidants, sulfur antioxidants, phosphorus antioxidants, amine antioxidants, lactone antioxidants, vitamin E antioxidants, and the like. It is done. Examples of the UV absorber include inorganic compound UV absorbers such as titanium dioxide, and organic compound UV absorbers such as benzotriazole, benzophenone, triazine, benzoate, and salicylate. In that case, these antioxidants and ultraviolet absorbers may be selected depending on the physicochemical properties of the pesticidal active ingredient contained in the inner core, and may be blended in an amount in which the effect is recognized.
[0042]
Furthermore, examples of the antistatic agent include inorganic compounds such as titanium oxide, zinc oxide, and magnesium oxide, and calcium phosphate compounds. Further, phosphate ester surfactants such as polyoxyethylene alkyl ether phosphates can also be used as antistatic agents. In addition, what is necessary is just to use an antistatic agent as needed, and should just make it the quantity which the antistatic effect is recognized in the range which does not impair the objective and effect of this invention.
[0043]
On the other hand, in the sustained-release agrochemical granule of the present invention, the second thermoplastic material hardly soluble in water of the outer layer portion is substantially the same material as the thermoplastic material used for the inner core, and two or more types are used. You may mix and use. Its melting point must be lower than that of the first thermoplastic material contained in the inner core. Specifically, the melting point of the second thermoplastic material is 40 ° C. to 70 ° C., preferably 50 ° C. to 69 ° C., More preferably, it is preferable to select in the range of 60 ° C to 68 ° C. Furthermore, since the second thermoplastic material is heated and melted to form a binder in the coating step, if the melt viscosity is low, adhesion of particles at the time of coating is reduced, which is preferable. Specific examples of materials suitable for the second thermoplastic material that satisfy the above-mentioned various conditions include plant waxes such as candelilla wax and tree wax, animal waxes such as beeswax, laurin, whale wax, and beef tallow, and paraffin wax. And petroleum waxes such as petrolatum, synthetic hydrocarbons such as Fischer-Tropsch wax, and modified waxes such as paraffin wax derivatives. Among these, paraffin wax (manufactured by Nippon Seiwa Co., Ltd., trade name paraffin wax 140, melting point: 61 ° C., trade name SP-0145, melting point: 63 ° C., paraffin wax 150, melting point: 66 ° C.) is more preferable. . The amount used depends on the amount of the pesticidal active ingredient contained in the outer layer part and the physical properties of the inorganic diluent carrier, but in the sustained-release pesticidal granule of the present invention, with respect to the total weight of the composition of the outer layer part, Usually, it is selected in the range of 1% by mass to 20% by mass, preferably 1% by mass to 15% by mass. In addition, content of a 2nd thermoplastic material is set to below the total oil absorption capacity of the composition of this outer layer part.
[0044]
The inorganic diluent carrier for the outer layer used in the sustained-release agrochemical granule of the present invention is not particularly limited as long as it shows at least almost water solubility, and the inorganic dilution for the inner core described above is not limited. If the material is almost the same as that of the carrier, the object can be sufficiently achieved. Therefore, for example, clay, silica, talc, bentonite, calcium carbonate, pumice, diatomaceous earth, vermiculite, perlite, attapulgite, and amorphous hydrous silicic acid, commonly known as white carbon, are usually used for agricultural chemical powders and granules. One or more so-called extenders and carriers can be used in combination.
[0045]
In the sustained-release agrochemical granule of the present invention, in addition to the inorganic diluent carrier, the outer layer portion can contain a surfactant and an auxiliary agent within a range not impairing the object and effect of the present invention. .
[0046]
In the sustained-release agrochemical granule of the present invention, as a surfactant that can be added to the outer layer portion, nonionic surfactants, anionic surfactants, cationic surfactants that are usually used in agrochemical formulations are used. And amphoteric surfactants. For example, alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene styryl phenyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan alkylate, polyoxyethylene phenyl ether polymer, polyoxyethylene alkylene aryl phenyl ether, polyoxyethylene Nonionic surfactants such as alkylene glycol, polyoxyethylene polyoxypropylene block polymer, lignin sulfonate, alkyl aryl sulfonate, dialkyl sulfo succinate, polyoxyethylene alkyl aryl ether sulfate, alkyl naphthalene sulfonate, Anionic surfactants such as polyoxyethylene styryl phenyl ether sulfate, alkyl Amine salts, quaternary ammonium salts, alkyl betaines, cationic surfactants and amphoteric surfactants such as an amine oxide. When these surfactants are added, one type may be used, but the same type or different types may be used in combination.
[0047]
In addition to the surfactant, auxiliary agents that can be added to the outer layer include solid organic acids such as aromatic carboxylic acids, polyvalent carboxylic acids, and sugar-derived carboxylic acids, water-soluble polymers, and the like. Specific examples of organic acids include dibasic acids such as succinic acid, malonic acid, succinic acid, maleic acid and fumaric acid, or hydroxy-substituted dibasic acids such as malic acid and tartaric acid, and sugar derivatives such as ascorbic acid and citric acid. Type carboxylic acid. Examples of the water-soluble polymer include polyvinyl alcohol, carboxymethyl cellulose, dextrin, hydroxyethyl cellulose, methyl cellulose, alginate, gelatin, pectin, pullulan, polyvinyl pyrrolidone, polyacrylate, polyethylene oxide and the like. The addition amount of the surfactant and these adjuvants is generally 0.01% by mass to 20% by mass, preferably 0.01% by mass to 10% by mass with respect to the total weight of the composition of the outer layer part as the total of both. % Is preferable.
[0048]
The sustained-release agrochemical granule of the present invention having the above-described configuration gradually releases two or more different agrochemical active ingredients having extremely different water solubility so as to be released at individual elution rates. In particular, it can be used as an agrochemical granule that can be suitably used as a granule for a rice seedling box. By using the sustained-release agrochemical granule of the present invention, 30 to 60 days required for pest control during rice planting to paddy rice cultivation, or longer than that required for rice seedling box granules It is possible to release the pesticidal active ingredient continuously and almost completely. In addition, the sustained-release agrochemical granule of the present invention can eliminate the drying step required in the method described in JP-A-2000-44404 at the time of production, so that the production cost can be kept low. There is also. The sustained-release agricultural chemical granule of the present invention is applied to a paddy rice seedling box before planting rice, for example, when it is used as a granule for a paddy rice seedling box. Moreover, when it is used as a granule for a seedling box, the application amount is 10 g to 100 g per paddy rice seedling box (about 30 cm × 60 cm), usually about 50 g, but is not particularly limited, and the agrochemical active ingredient in the preparation What is necessary is just to decide by content, the required control period of a pest, and the number of seedling boxes used per 10a.
[0049]
In addition, when the pesticide granule of the present invention is applied to, for example, a paddy rice seedling box, the pesticide granule that is entrained per seedling when the seedling is sprayed uniformly over the entire seedling box and the seedling is transplanted into a paddy field. It is preferable not to cause a large variation in the number of pieces. For that purpose, the particle size of the granule, specifically, the opening used for sieving to determine the particle size distribution is made too large, and the number of agrochemical granules corresponding to a predetermined application rate becomes too small. It is desirable to avoid this. That is, when used as a granule for a seedling box for paddy rice, it is desirable to select the openings so that the number of grains per 1 g of agrochemical granule is 300 or more, preferably 400 or more. However, although it depends on the content of the inorganic diluted carrier contained, the bulk specific gravity, etc., it is necessary to avoid that the particle size of the granule becomes too small and floats in water. It is possible to add a surfactant to the outer layer to increase the surface affinity for water and prevent the above problems, but the number of grains per gram of agricultural chemical granules exceeds 2000. It is desirable to keep it to a certain extent.
[0050]
【Example】
Next, the present invention will be described in more detail by way of examples. In particular, an example in which the sustained-release agrochemical granule of the present invention is used as a granule for a rice seedling box is shown, but the method for preparing such a seedling box granule and the resulting formulation are not limited in any way. For example, (RS) -1-methyl-2-nitro-3- (tetrahydro-3-furylmethyl) guanidine exemplified as an agrochemical active ingredient of the inner core, and various kinds of agrochemicals described above as probenazole exemplified as an agrochemical active ingredient of the outer layer portion The sustained-release agrochemical granule of the present invention may be used in place of the active ingredient or each thermoplastic material and inorganic diluent carrier used in the inner core and outer layer exemplified in the examples may be replaced with the other ones described above. It is also possible to obtain granules for rice seedling box.
[0051]
In addition, all the mixture ratios shown in the specific examples described below are mass% unless otherwise specified.
[0052]
(Reference Examples 1-6)
The inner cores of Reference Examples 1 to 6 were obtained at the blending ratios shown in Table 1 according to the production methods shown below.
[0053]
As an agrochemical active ingredient contained in the inner core, (RS) -1-methyl-2-nitro-3- (tetrahydro-3-furylmethyl) guanidine (hereinafter referred to as “Compound 1”) synthesized according to the method described in JP-A-7-179448. ), White carbon, talc, calcium carbonate as the inorganic diluent carrier, montanic acid wax (trade name Luwax S, manufactured by BASF Corp., melting point: 75 to 85 ° C., acid value as the first thermoplastic material 135-160 mgKOH / g), and / or montanic acid ester wax (manufactured by BASF, trade name Luwax E, melting point: 75-85 ° C., acid value: 10-25 mgKOH / g) is attached to the heating device The mixture was then heated to 83 ° C. or 90 ° C. and mixed. This mixture was extruded and granulated using a horizontal extrusion granulator (a screen having an opening of 0.7 mm or 0.8 mm) maintained at 90 ° C. by a heating device. Granules obtained under the charge composition and production conditions shown in Table 1 were crushed and sieved to obtain granulations (inner cores) of Reference Examples 1 to 6.
[0054]
[Table 1]

[0055]
(Test Example 1): Inner core dissolution test
The elution rate of the agrochemical active ingredient (compound 1) released from the inner core obtained in Reference Examples 1 to 6 was measured by the method shown below.
[0056]
That is, when all the pesticidal active ingredients each containing the inner core obtained in Reference Examples 1 to 6 were eluted in a 50 ml sealed sample tube containing 25 ml of standard 3 degree hard water, the pesticidal active ingredients (compounds) An amount corresponding to the concentration at which the concentration of 1) was 920 ppm was added and submerged in water. In that state, after standing at 25 ° C. for a predetermined time, the whole amount was filtered off, and the amount of the pesticidal active ingredient (compound 1) dissolved in the filtrate was measured by HPLC. From the measured values, the dissolution rate was calculated based on the following formula, and the results are summarized in Table 2.
[0057]
Elution rate = (Agricultural active ingredient content in filtrate / Agricultural active ingredient content in granules) × 100
As is clear from the results shown in Table 2, the granulated product (inner core) of Reference Examples 1 to 6 corresponding to the inner core in the sustained release agricultural chemical granule of the present invention contains the agrochemical active ingredient (compound 1) contained therein. It is possible to release it almost completely as well as to release it for an arbitrary period in the range of one week to two months.
[0058]
[Table 2]

[0059]
(Examples 1-12)
The outer layer portion is coated and formed on the granulated product of Reference Examples 1 to 6 as the inner core at the blending ratio shown in Table 3 to obtain granules for seedling boxes for paddy rice of Examples 1 to 12 It was.
[0060]
First, as the raw material powder of the outer layer part, the probenazole raw material of the agrochemical active ingredient to be contained, clay as the inorganic diluent carrier, paraffin wax (made by Nippon Seiwa Co., Ltd., trade name paraffin wax 150, as the second thermoplastic material) Melting point 66 ° C.) and dialkylsulfosuccinate (trade name Sorpol-5050, manufactured by Toho Chemical Industry Co., Ltd.) as a surfactant, or citric acid as an auxiliary agent, if necessary, in a floating mixer. Mixed.
[0061]
Next, any one of the granulated products (inner core) obtained in Reference Examples 1 to 6 is placed in a floating mixer equipped with a heating device and mixed while heating up to 70 ° C. The rice seedling boxes of Examples 1 to 12 were coated so as to be particles having a particle size corresponding to a target particle size distribution and an opening of 1.0 to 2.0 mm. A granule was obtained. In addition, as for the granule obtained here, the number of particles per 1g was about 400.
[0062]
[Table 3]

[0063]
(Comparative Examples 1 and 2)
Two types of pesticide active ingredients (Compound 1 (insecticide) and probenazole (bactericidal agent)) In order to obtain a granule in which both are included in the granulated product and are not provided with a coating layer, the same granulation method as the granulated product (inner core) of Reference Examples 1 to 6 at the blending ratio shown in Table 4 Granulate with Prepared. The resulting granulated product After pulverization, the mixture was sieved to obtain granules of Comparative Examples 1 and 2.
[0064]
[Table 4]

[0065]
(Comparative Examples 3-5)
As shown in Table 5, two types of pesticide active ingredients (Compound 1 (insecticide) and probenazole (bactericidal agent)) And a granulated product (inner core) was obtained by the same granulation method as in Reference Examples 1-6. Then, the outer layer part raw material powder which does not contain any agrochemical active ingredient was coat | covered in the same procedure as Examples 1-12, and the granule of Comparative Examples 3-5 was obtained.
[0066]
[Table 5]

[0067]
(Comparative Examples 6-8)
As shown in Table 6, Probenazole (bactericide) And a granulated product (inner core) was obtained by the same granulation method as in Reference Examples 1-6. Then Compound 1 (insecticide) In the same manner as in Examples 1 to 12, the outer layer part raw material powder mixed with was coated on the surface of the granulated product (inner core) to obtain granules of Comparative Examples 6 to 8.
[0068]
[Table 6]

[0069]
(Comparative Example 9)
In order to obtain the composition shown in Table 7, Compound 1 (insecticide) After spraying the methanol solution that had been dissolved on the surface of a spherical solid carrier (trade name: Izu silica stone, particle size: 0.3 to 1 mm, manufactured by Tokai Kogyo Co., Ltd.), left in a 50 ° C. dryer for 3 hours. The methanol was removed to obtain an inner core that was not released slowly. Next, the composition shown in Table 7 Probenazole (bactericidal agent) The outer layer raw material powder mixed with and mixed was coated on the surface of the inner core in the same manner as in Examples 1 to 12 to obtain granules of Comparative Example 9.
[0070]
[Table 7]

[0071]
(Test Example 2): Dissolution test of granule for rice seedling box
About the granule obtained in said Examples 1-12 and Comparative Examples 1-9, the elution rate of the agrochemical active ingredient released from each granule was measured.
[0072]
(1) Compound 1 (insecticide) Elution rate
In Examples 1-12 and Comparative Examples 1-9 Obtained Of the two types of active ingredients contained in granules, released from each granule Compound 1 (insecticide) Was measured by the method shown below.
[0073]
That is, each granule obtained in Examples and Comparative Examples is contained in a 50 ml-capacity sample tube with 25 ml of standard 3 degree hard water. Compound 1 (insecticide) When all of the Compound 1 (insecticide) An amount corresponding to the amount at which the concentration of 920 was 920 ppm was added and submerged in water. In that state, after standing at 25 ° C. for a predetermined time, the whole amount is separated by filtration and dissolved in the filtrate. Compound 1 (insecticide) The amount was measured by HPLC. From the measured values, the dissolution rate was calculated based on the following formula, and the results are summarized in Table 8.
[0074]
Elution rate = (in the filtrate Insecticide Amount / in granules Insecticide Amount) x 100
[0075]
[Table 8]

[0076]
As is clear from the results shown in Table 8, in the granule of the example, it is possible to continuously release the insecticidal active ingredient contained in the inner core for about 1 to 3 months, The entire amount of insecticidal active ingredient contained completely was released. On the other hand, Comparative Examples 1 and 2 not provided with a coating layer, Comparative Examples 6 to 8 containing Compound 1 in the outer layer portion instead of the inner core, or Inner core not subjected to the sustained release technique In Comparative Example 9 in which Compound 1 was contained, none was sustained-released, and the dissolution rate reached nearly 100% in about 1 to 3 days.
[0077]
(2) Probenazole (bactericidal agent) Elution rate
In Examples 1-12 and Comparative Examples 1-9 Obtained Of the two types of active ingredients contained in granules, released from each granule Probenazole (bactericidal agent) Was measured by the method shown below.
[0078]
That is, each granule obtained in the examples and comparative examples is contained in a 1000 ml-capacity Erlenmeyer flask containing 1000 ml of ion-exchanged water. Probenazole (bactericidal agent) When all of the Probenazole (bactericidal agent) An amount corresponding to an amount of 30 ppm was submerged in water. In that state, it was allowed to stand at 25 ° C. Next, 1 ml of water is sampled from a depth of 5 cm every predetermined time, Fungicide The concentration was measured by HPLC. In the test granules Fungicide The concentration when the total amount was eluted in 1000 ml of water in the Erlenmeyer flask was a condition that reached 30 ppm, and the measured disinfectant concentration value was divided by 30 ppm to obtain the dissolution rate. The results are summarized in Table 9.
[0079]
[Table 9]

[0080]
As is apparent from the results shown in Table 9, each granule of the example can release a certain bactericidal agent for about 3 months, and the total amount of the bactericidal agent contained in the outer layer portion is as follows. Almost completely released. On the other hand, in the granules of Comparative Examples 3 to 8 containing the bactericide in the inner core, only a part of the content was eluted even after about 2 months, and therefore extremely low elution It was a rate.
[0081]
【The invention's effect】
In the coated sustained-release pesticidal granules of the present invention, when two or more kinds of pesticidal active ingredients having extremely different water solubility are contained, particularly when one of the water solubility is 1000 ppm or more, these two or more kinds are used. Each of these agrochemical active ingredients can be gradually released, and for example, an agrochemical mixed granule suitable for a granule for a seedling box for paddy rice can be obtained. Further, in the coated sustained-release pesticidal granules of the present invention, the total amount of the two or more pesticidal active ingredients contained therein can be almost completely released. The pesticidal active ingredient to be sprayed does not finish elution and there is no fear that a part of it remains in the granules. Furthermore, the coated sustained-release agrochemical granule of the present invention does not require the inner core to be coated particles whose surface is coated with a resin in the production thereof, and an extra step such as a drying step provided after the resin coating. Therefore, there is an advantage that the manufacturing cost can be kept low while adopting a dosage form having a two-layer structure.

Claims (6)

A sustained release agrochemical granule used to continuously elute and supply agrochemical active ingredients to an aqueous medium,
The granule has a configuration of a coated granule composed of an inner core and an outer layer portion covering the surface thereof,
The inner core is a granulated product comprising at least one agrochemical active ingredient having a water solubility at 20 ° C. of 1000 ppm or more and 10% or less, an inorganic diluent carrier, and a first thermoplastic material that is hardly soluble in water. Yes,
The outer layer portion has a melting point lower than that of the first thermoplastic material contained in the inner core, at least one agrochemical active ingredient having a water solubility of 0.01 to 500 ppm at 20 ° C., an inorganic diluent carrier, and It is a coating layer composed of a second thermoplastic material which is a different material and hardly soluble in water,
The sustained-release pesticide granule is characterized in that controlled release elution control is carried out for the agrochemical active ingredient contained in the inner core and the agrochemical active ingredient contained in the outer layer part by the constitution of the coated granule. The sustained-release agricultural chemical granule according to claim 1, wherein the outer layer part further contains a surfactant. The sustained-release agrochemical granule according to claim 1 or 2, wherein the first thermoplastic material hardly soluble in water contained in the inner core is a montanic acid wax and / or a montanic acid ester wax. The sustained-release agrochemical granule according to any one of claims 1 to 3, wherein the second thermoplastic material that is sparingly soluble in water contained in the outer layer portion is paraffin wax. The agrochemical active ingredient contained in the inner core is (RS) -1-methyl-2-nitro-3- (tetrahydro-3-furylmethyl) guanidine,
The sustained-release agrochemical granule according to any one of claims 1 to 4, wherein the agrochemical active ingredient contained in the outer layer part is probenazole. A method for producing the sustained release agricultural chemical granules according to claim 1,
When forming a coating layer that is an outer layer portion on the surface of the granulated product that becomes the inner core,
The second thermoplastic material constituting the coating layer is heated and melted to achieve a coating on the surface of the granulated material, and heated to a temperature that does not reach the melting point of the first thermoplastic material contained in the inner core. A method for producing a sustained-release agrochemical granule, characterized by comprising: