Agrochemical compositions in the form of dispersable granules

Details Agrochemical compositions in the form of dispersable granules Agrochemical compositions in the form of dispersable granules

1999-06-01

2001-08-14

Kulkosky, Peter F. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C424S043000

Reexamination Certificate

active

06274156

ABSTRACT:

The subject of the present invention is a new agrochemical composition and a containerization system comprising the said composition.
Containerization systems are known, especially by European Patent Publication No. EP 0544602, comprising effervescent dispersible granules of a material which is active in agriculture placed in a bag, the wall of which is a film consisting of a film-forming material which is soluble or dispersible in water. Such systems offer the user, especially the farmer, a much appreciated convenience of use and especially the possibility of quickly obtaining, and without specific stirring means, a homogeneous spray liquid (known as slurry) while making possible high safety of use.
However, such granules are usually manufactured by so-called dry agglomeration or granulation techniques, that is to say without solvent and especially without water. Such techniques make it desirable to prepare, prior to the granulation, a very fine powder, that is to say a powder whose constituent particles have a size of between 6 and 30 &mgr;m and preferably between 8 and 20 &mgr;m. Now, these powders are capable of coming into contact either directly with the skin of the people who are handling them or, after their accidental suspension in the air in the form of clouds, with the upper respiratory tracts of these same people. Such contacts can occur with the operators present in an industrial plant, during possible escapes when mixers are opened, or alternatively with the operators who carry out cleaning of the equipment, whether mixers or granulators, or alternatively with the operators who carry out the sampling necessary for monitoring the manufacturing process. Now, it is desirable to limit as far as possible, indeed to entirely prevent, any contact of this type in the case of active materials which can exhibit a risk of toxicity, in order to ensure the safety of the operators and to guarantee the cleanliness of the manufacturing sites.
Moreover, the intimate contact in these granules between the active material, which can have traces of residual moisture, and the effervescent agent, which is hygroscopic, is often harmful to the behaviour on storage, that is to say to maintaining the required qualities of the granules, especially regarding their ability to effervesce, due to passivation phenomena.
Japanese Patent Application 4-226901, published on Aug. 17, 1992, indeed mentions a soluble sachet containing dispersible granules of active material, on the one hand, and effervescent granules without active material, on the other hand, which can contribute to reducing these passivation phenomena. However, the dispersible granules described are manufactured by compacting with rollers, which is a dry granulation technique, so that this patent application entirely ignores the critical importance of the problem to be solved, which is related to the industrial hygiene conditions of the manufacture of the product.
An object of the present invention is to make available agrochemical compositions whose manufacture presents a decreased risk for the workers.
Another object of the present invention is to make available agrochemical compositions which are easier to manufacture.
Another subject of the present invention is an improvement in the behaviour on storage of the agrochemical compositions.
Another object of the present invention is to make available to farmers concentrated agrochemical compositions which make it possible, after dilution with water, to easily and quickly obtain a homogeneous spray liquid.
Another object of the present invention is to make available to farmers concentrated agrochemical compositions whose handling offers improved safety.
Another object of the present invention is to make available to the user a concentrated agrochemical composition in a soluble sachet whose rate of dissolution in water is increased.
It has now been found that these aims could be achieved in all or in part by virtue of the compositions and containerization systems according to the invention.
In the present invention, the percentages indicated are percentages by weight, unless otherwise specified, and active materials are understood to mean materials which are active in agriculture such as plant protection agents, agrochemical products, pesticides, growth regulators or plant nutrient agents. The pesticides are more particularly herbicides, insecticides, fungicides, nematicides and acaricides.
Apparent density within the meaning of the present invention is essentially the ratio of the weight of a specific amount of granules to the volume occupied by these same granules after settling carried out under standard conditions, that is to say under the following conditions: 80 g of on-test granules are poured into a 250 cm
3
measuring cylinder which is subjected to 50 periodic movements composed of a movement from the bottom upwards with an amplitude of 2.5 cm followed by a movement from the top downwards of the same amplitude. Each period lasts 2 seconds. At the end of the operation, the volume occupied by the granules in the measuring cylinder is noted, enabling the apparent density of the granules to be deduced.
The first subject of the present invention is agrochemical compositions which are solid concentrated compositions, characterized in that they are a homogeneous mixture:
of one (or a number of) concentrated compositions A in the form of dispersible granules, each granule containing at least one active material and not containing an effervescent agent, and having a cumulative pore volume of between 0.17 and 0.35, preferably between 0.20 and 0.30, ml/g and having an apparent density of between 0.35 and 0.8, preferably between 0.4 and 0.7, g/cm
3
; and
of a concentrated composition B in the form of dispersible granules, each granule containing an effervescent agent and not containing an active material, having a cumulative pore volume of between 0.020 and 0.13, preferably between 0.025 and 0.10, ml/g and having an apparent density of between 0.8 and 1.5 g/cm
3
, preferably between 1.0 and 1.4 g/cm
3
;
the A/B quantitative ratio being between 0.01 and 30, preferably between 0.05 and 10 and more preferentially still between 0.08 and 5.
The cumulative pore volume of the granules according to the invention is measured using a mercury porosimeter according to techniques known per se.
Dispersible granule is understood to mean a solid and cohesive agglomerate of constituent particles which have a size of between 1 and 20 &mgr;m, which agglomerate, after mixing with water, disintegrates or disperses to give a homogeneous and stable suspension. Presentation as a dispersible granule offers the user great convenience of use which makes them very desirable.
The possibilities of chemical reaction between the effervescent agent of the solid composition B and possible residual moisture in the active material of the solid composition A are very greatly restricted due to the very low exchange surface area between these two granulated solid compositions, so that the result thereof is a behaviour on storage of the composition according to the invention which is greatly improved.
The difference in the porosity characteristics between the dispersible granules containing the active material(s) and the effervescent dispersible granules which do not contain them is particularly advantageous in promoting an improved dispersion of the agrochemical composition according to the invention. In fact, water more rapidly penetrates inside granules containing the active material(s), despite the strongly hydrophobic nature of the active materials used in practice, and the effervescent inert granules more efficiently contribute to the rapid disintegration of the dispersible granules of active material.
According to an advantageous aspect of the invention, the material which is active in agriculture which can be used in the dispersible granules of the composition A is a pesticide, preferably an insecticide, a nematicide or an acaricide. It is in fact always desirable, even for a material which is active in agriculture whi

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