Herbicide preparation, a process for producing it and an...

Plant protecting and regulating compositions – Plant growth regulating compositions – Organic active compound containing

Reexamination Certificate

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C504S363000

Reexamination Certificate

active

06180566

ABSTRACT:

The present invention relates to concentrated herbicide preparations comprising at least one herbicide being fine-grained and suspended in an aqueous electrolyte solution, said herbicide comprising at least one primary, secondary or tertiary amino group and at least one carboxylic acid group and at least one phosphor containing acid group, a process for producing it and an activating, concentrated additive for application in combination with said herbicides.
It is customary to produce herbicide preparations as suspensions in water. But normally the content of electrolytes in the aqueous phase is low, since a high content of electrolytes in water has a tendency to lower the solubility of the additives being necessary to stabilize the herbicide suspension. Amongst these additives, the surfactants are particularly important, said surfactants being necessary to ensure the wetting in connection with the grinding of the suspended herbicide, and being often desirable in connection with the intrusion of the herbicides in the weeds. Often only a few surfactants are suitable to ensure, in an appropriately broad temperature interval from −10° C. to approximately 50° C., that the suspension is effectively wetted and also flows satisfactorily. Additionally the suspensions almost always contain soluble, viscosity regulating compounds, ensuring that the viscosity in a broad temperature interval does not fall below a certain low value in order to avoid precipitation of the suspended herbicide. A too high content of electrolytes in the aqueous phase might lead to the gelatination or precipitation of the viscosity regulating compounds. The surfactants as well as the viscosity regulating compounds and eventually a certain amount of a dissolved glycol component can ensure, that the suspension after freezing and subsequent unfreezing thaws out again as a flowable, not gritty suspension.
In published european patent application EP 388.239 A1 pesticide suspensions are described, in which a certain amount of electrolytes is desirable. The suspension of finely ground pesticides in a concentration from 10-70% by weight in aqueous, structured systems of surfactants is described. The following pesticides are mentioned explicitly: ethofumesate, phenmedipham, dazomet, mancozeb, methylene bisthiocyanate, amitraz and triforine. None of these pesticides contains both an acid and an amino group. The wording “structured systems of surfactants” is intended to mean aqueous systems, in which the surfactants form mesophases comprising structures larger than conventional spherical micelles and mutually interacting to form thixotropy in the aqueous medium. The structure comprises multilayers of spherulites or lamellae dispersed or emulsified as rods or discs in an outer aqueous phase, the size being normally 0.5-20 &mgr;m. In the 14 examples of the application the not surface active electrolytes are present in an amount of 1.2-6.4% by weight of the total composition. It is a characteristic feature of this system, that the surfactant and the electrolyte must be adapted to each other as regards composition and amount to obtain the desired, stable structure.
Hungarian patent HU 200076 discloses, how the sedimentation tendency of aqueous suspensions may be avoided by addition of electrolytes to the suspensions. According to the patent lumps of surfactant will be formed when an electrolyte is added, causing the liquid to be turbid as the stabilisation takes place. It is not clearly evident from the patent whether the stabilisation is caused by crystallisation of surfactant on the surface of the suspended pesticide or by crystallisation of surfactant as a new phase (compare EP 388.239), or by the viscoelasticity caused by the precipitation. The improved stability is evaluated by centrifugation through indication of the not sedimented part. Only one of the samples (table 7) is subjected to normal long term storage. The preferred electrolyte is diammonium hydrogen phosphate. According to the patent 5-10% diammonium hydrogen phosphate provides optimal effect. It is not surprising that addition of electrolyte increases the stability of an aqueous suspension, the viscosity normally being increased and frequently causing the suspension to gelatinate. It is contrarily surprising, that the patent does not indicate the viscosity of the evaluated suspensions. All the examples comprise glycol, frequently about 10%. This addition counteracts the salting-out caused by the electrolyte.
The adjustment of the viscosity of a suspension by changing an eventual content of electrolyte, surfactant and glycol being well-known, this technic, however, is almost never practiced at the final adjustment of viscosity, because the effect is very dependent of temperature and difficult to reproduce. Centrifugal tests are notoriously of no relevance for the long term stability of suspensions. HU 200076 does not disclose that the amount of emulsifier necessary for sufficient wetting of the suspended pesticide may be reduced when an electrolyte is added. Similarly it is not disclosed in HU 200076, that the surfactant or the viscosity regulating polysaccharide may be omitted following the addition of an electrolyte. There is a certain overlap between the intervals of added electrolyte in HU 200076 and in the present invention, but the optimal amount of electrolyte in the present invention is above the most effective in HU 200076. The described pesticides are atrazine, isoproturon, bensultap, fluomethuron, lindane, thiophanat-methyl and elementary sulfur. None of these pesticides comprises a carboxylic acid group or a phosphor containing acid group.
It is well known that ammonium sulphate acts synergistically on the biological effect of glyphosate and glufosinate. For instance the patent literature contains many examples of combinations of glyphosate and ammonium sulphate, and in practice the farmer usually adds supplementary ammonium sulphate when diluting the glyphosate for use.
Danish patent application no. 2348/88 describe liquid, aqueous solutions of glyphosate with ethoxylated monoamines as surfactants. The possibility of dissolving additional ammonium sulphate exists, but this will lead to a lowering of the dissolvable quantity of glyphosate. Therefore, the maximum amount of glyphosate in a solution containing 280 g/l ammonium sulphate is approximately 120 g/l.
UK patent application GB 2.233.229 A describes a similar system, the ethoxylated monoamines being replaced by ethoxylated diamines. The typical, aqueous solutions contain 200 g/l ammonium sulphate and 75 g/l of glyphosate as its isopropylammonium salt.
UK patent application GB 2.245.170 A claims solutions of glyphosate containing ethoxylated phosphate esters as surfactants. In the examples, where ammonium sulphate has been added supplementary to the formulation in amounts of 200-300 g/l, the glyphosate constitutes 75 g/l corresponding to 100 g/l of the isopropylammonium salt.
In European patent application EP 441.764 A1 is mentioned, that alkoxylated, quaternary ammonium compounds especially coethoxylated-propoxylated quaternary ammonium compounds, is environmentally more acceptable and less skin and eye irritating than ethoxylated fatty amines. It is stated, that aqueous solutions of glyphosate in combinations with said surfactants also can contain ammonium sulphate, but no examples with such formulations are given. On the other hand two solid compositions containing ammonium sulphate are described.
In European patent application EP 498.785 A1 glyphosate formulations are mentioned, which contain esters of sorbitol and fatty acids as surfactants in combination with another surfactant. It is mentioned, that these formulations whether aqueous solutions or solid, finely distributed formulations may also contain ammonium sulphate or other inorganic ammonium salts. The system, however, seems to be best suited for solid formulations.
European patent application EP 498.145 A1 describes solid compositions containing glyphosate as free acid or salt, an inorganic ammonium salt (preferably ammonium

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