FR2509575A1 - Effervescent herbicidal granules - contg. acid herbicide and alkali metal carbonate - Google Patents

Abstract

Water soluble granules contain 50-90% of an acidic herbicide or plant growth regulant (I), 10-40% of an alkaline carbonate or bicarbonate, and 0-10% of impurities from the herbicidal acid (I). (I) is pref. 2,4-D, MCPA, 1-naphthalene acetic acid, and esp. acifluorfen. The alkaline carbonate is pref. Na2CO3 or NaHCO3, and the compsns. pref. contain 1-10% of additives such as surfactants and lubricants. The granules effervesce and dissolve rapidly in water, giving a herbicidal or growth-regulating solution ready for spraying. Such granules are suitable for use with hygroscopic materials as (I), and avoids both the need to store solutions and the difficulties of handling powders. In an example 96% pure acifluorfen (7.23g), anhydrous sodium carbonate (1.12g) and aluminium stearate (0.01g) were ground in a ball mill and sieved, then compressed to small granules. Those of 20-60 mesh size were separated. When added to water they effervesced and dissolved ready for spraying.

Description

The present invention relates to compositions
bio-active consisting of effervescent granules containing a herbicide or acid growth regulator, an alkali carbonate or bicarbonate, and optionally additives such as mold release agents, binding agents and / or fillers.

 We know the herbicide acifluorfen-sodium salt, sold under the brands of Tackle and Blazer and consisting of 5-c2-chloro-4- (trifluoromethyl) phenoxy) -2-nitrobenzoate sodium; the acifluorfen is therefore 5- [2-chloro-4- (trifluoromethy) phenoxy3 -2-nitro benzoic acid.

 In the present description, the compounds are designated under their chemical name according to the French nomenclature, however the figures indicating the position of the substituents are placed before the latter in accordance with the Anglosaxon nomenclature.

 The formulations marketed for acifluorfen-sodium salt are compositions comprising as main constituents of water (76 S) and only about 24% of herbicide.

 An object of the invention is to produce dry herbicidal compositions, easily dispersible in water and which contain a fairly high concentration of active herbicidal material.

 On this point, it should be noted that the acifluorfen-sodium salt being hygroscopic, it is not in itself a herbicidal concentrate suitable commercially.

 Another object of the invention is to provide herbicidal compositions which are not in powder form. In fact, people who apply pesticide products are increasingly turning away from compositions in powder form because of the nuisance and inconvenience in handling the powders (need for a mask, soiling, etc.).

 Various kinds of water-dispersible pesticide granules are well known from tailors, in particular those called self-dispersible granules (in English "dry flowables"). In particular, effervescent granules have been proposed (French patents 2,290,844 and English patents 847,370), these granules comprising at least three essential constituents: the active material, the carbonate and an acid capable of reacting with the carbonate.

 Another object of the invention is to provide herbicidal compositions as simple as possible and containing a high content of active material.

 Another object of the invention is to provide dry herbicidal compositions which can easily use active materials such as acifl-uorfen-sodium salt.

 It has now been found that these various aims could be achieved by virtue of the compositions according to the invention.

 The subject of the invention is therefore pesticide, bioactive, and more particularly herbicide compositions, in the form of water-soluble granules, said granules comprising 50 to 90% by weight of an acidic herbicide (or growth regulator). and about 10 to 40% of an alkali metal carbonate or bicarbonate, especially potassium or preferably sodium. The amount of active acid material is preferably between 60 and 75%. The compositions according to the invention also optionally contain 0 to 10% of impurities of the herbicidal acid (isomers or by-products of manufacture).

 It should be understood that the term granules should not be taken in a limited sense, and that it includes any other similar form such as grains, pastilles, tablets.

 Generally, these granules have at least one dimension between 0.1 and 50 mm, preferably between 0.3 and 3 mm.

 The relative amount of herbicidal active material relative to the carbonate is such that the carbonate or bicarbonate / acid active material molar ratio is between 1 and 3, preferably between 1.3 and 9.

 The compositions according to the invention may contain minor amounts (for example 0.1 to 10%) of other additives such as lubricants or release agents (for example 0.05 to 1% of aluminum stearate, or less ), stabilizers, binders, agents promoting grain cohesion (for example urea or cellulose derivatives), agents promoting disintegration.

 The compositions according to the invention may also contain other additives useful for the pesticide application under consideration. Thus, it may be necessary to add surfactants or wetting or dispersing agents or any other product capable of promoting the penetration of the active material into the vetoetal.

 These surfactants can be emulsifying, dispersing or wetting agents of ionic or nonionic type or a mixture of such surfactants. Mention may be made, for example, of salts of polyacrylic acids, salts of lignosulfonic acids, polycondensates of ethylene oxide on fatty alcohols or on fatty acids or on fatty amines, substituted phenols (in particular alkylphenols or arylphenols), salts of sulfosuccinic acid esters, oes derived from taurine (in particular alkyltaurates), phosphoric esters of polyoxyethylated alcohols or phenols, esters of fatty acids and polyols; derivatives with sulphate, sulphonate, phosphate functions of the above compounds.

 Preferably, in the compositions according to the invention, the grains are separated from each other and their mass can flow when poured.

 According to an advantageous variant, the compositions of the invention do not contain any inert content, in particular no inert water-insoluble content.

 Acitluorten is the particular active ingredient suitable for the invention, but it is also possible to use 5- [2-chloro-4- (trifluoromethyl) phenoxy j -2-nitro-N-methanesulfonyl-benzamide, acid 2, 4-dichlorophenoxyacetic, 2-methyl-4-chlorophenoxyacetic acid, l-naphthalene acetic acid (as growth regulator), methyl paraaminophenylsulfonylcarbamate.

 The granules according to the present invention can be made by compression (for example using a press or a compactor) of the constituents so as to obtain a tablet, then by granulation of the compact material obtained.

 Obtaining ready-to-use slurry (solution or suspension) from the granules according to the invention is carried out simply by placing said granules in water in an amount corresponding to the desired concentration for the active material.

 The CO2 released during effervescence causes rapid stirring of the solution; this stirring accelerates the dissolution of the ingredients in water and the salification of the acid; moreover, the use of an acid in the formulation makes it possible to incorporate into the composition a higher content of active material than when the salt is added separately: this is a particularly advantageous advantage in the phytosanitary field where it is desirable to handle as little quantity of products as possible.

 The following examples, given without limitation, illustrate the invention and show how it can be implemented.

Example 1
One mixes - 7.239 acifluorfen of 96% purity - 1.129 anhydrous sodium carbonate - 0.01 g of aluminum stearate.

 The whole is ground in a glass bead mill comprising the same poios of glass beads of Smm .e diameter. The mixture is then sieved and then compressed. The pellets obtained are lightly crushed in a mor third then pounded, sieved and the fraction of 20 g 60 mesh is kept (American standard of sieves, 0.25-0.84 mm).

 By adding these granules to water, effervescence and dissolution takes place, a clear solution ready for spraying is obtained, except that it comprises in suspension particles of aluminum stearate.

 The mixture contains 83% herbicidal acid equivalent to 88% of the salt.

Example 2:
One mixes - 7.229 of acifluorfen (purity 96%) - 1.85g of sodium bicarbonate - 0.01 of aluminum stearate.

 The mixture is treated as in Example 1. When added to water, results equivalent to those of Example 1 are obtained.

 The mixture contains 76.4 o herbicidal acid equivalent to 81% salt.

Example 3:
Mixing: - 74.9 g of acifluorfen of 80% purity - 25 g of anhydrous sodium carbonate - 0.1 g of aluminum stearate.

 The whole is finely ground in a mechanical mill so as to obtain particles of 3 to 50 microns.

 The mixture thus obtained is compressed under a pressure of 20 bars by a tablet making machine. The pellets obtained are crushed, then sieved so as to retain the grains of size 20 to 60 mesh (0.25 to 0.84 mm). These trains contain approximately 60 S of acifluorfen equivalent to 63.6 W of its sodium salt.

 These granules added to water disintegrate with the departure of carbon dioxide and the formation of the sodium salt of the acifluorfen-sodium salt, as in the previous examples.

Example 4:
Mixed - 63 g of acifluorfen of 80% purity - 25 g of anhydrous sodium carbonate - 0.1 g of aluminum stearate.

 The whole is ground as in Example 3.

 The mixture obtained is compressed under a pressure of 5 bars by a machine 4 to make pellets. The pellets obtained are crushed and then sieved so as to retain the grains of size 15 q 30 mesh (0.5 to 1-2 mm). These grains contain 57.2% acifluorfen equivalent to 60% of its sodium salt; when put in water, they disintegrate perfectly and give an aqueous solution of the herbicide acifluorfen-sodium salt.

Example 5
The procedure is as in Example 3 but replacing the 25 g of carbonate with 18 g of carbonate and 7 g of urea.

 Granules of similar size are obtained and perfectly satisfactory as regards their disintegration in water.

Example 6:
Example 3 is reproduced successively with 5 r2-chloro-4- (trifluoromethyl) phenoxyf -2-nitro-N-methanesulfonyl-benzamide, 2,4-dichlorophenoxyacetic acid, 2-methyl-4-chlorophenoxyacetic acid and l-naphthalene acetic acid.

 In the same way, granules are obtained which satisfy and disintegrate well in water.

Claims (10)

1) Bioactive compositions in the form of water-soluble granules, the said granules being characterized in that they comprise 50 to 90% of a herbicidal acid or growth regulator as well as 10 to 40% of carbonate or bicarbonate alkaline and possibly O to 10% of impurities of the herbicidal acid. 2) Compositions according to claim 1 characterized in that the active material is herbicide. 3) Composition according to one of claims 1 or 2 characterized in that the alkali carbonate or bicarbonate is a sodium carbonate or bicarbonate. 4) Compositions according to one of claims 1 to 3 characterized in that they contain 60 to 75% of acidic herbicide. 5) Compositions according to one of claims 1 to 4 characterized in that the carbonate or bicarbonate / acid molar ratio is between 1 and 3, preferably between 1.3 and 2. 6) Compositions according to one of claims 1 to 5 characterized in that the granules are separated from each other and that their assembly is capable of flowing and that they do not contain an inert filler insoluble in water. 7) Composition according to one of claims 1 to 6 characterized in that they contain 0.1 to 10% of an additive such as mold release agent, agent promoting disintegration, surfactant. 8) Compositions according to one of claims 1 to 7 characterized in that they contain 0.05 to 1 S of aluminum stearate. 9) Compositions according to one of claims 1 to 8 characterized in that the herbicide is acifluorfen. 10) Compositions according to one of claims 1 to 8 characterized in that the acid active material is chosen from the group consisting of 5-02-chloro-4- (trifluoromethyl) phenoxyl-2-nitro-N-methane sulfonylbenzamide, 2,4-dichlorophenoxyacetic acid, l-naphthalene acetic acid.