Plant protecting and regulating compositions – Plant growth regulating compositions – Plural active ingredients
Reexamination Certificate
1998-11-24
2003-12-23
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Plural active ingredients
C504S128000, C504S206000, C504S365000, C514S975000
Reexamination Certificate
active
06667276
ABSTRACT:
The invention relates to the technical field of surfactant systems for liquid aqueous or aqueous-organic formulations (preparations), preferably comprising an organic and an aqueous phase in the form of a microemulsion. The invention preferably relates to surfactant systems for single-phase or multi-phase formulations of one or more active compounds, where at least one of the active compounds is readily soluble in water. In this context, the active compounds can be, for example, active compounds from the fields of medicine or agriculture, or else other substances having particular technical function, such as, for example, colorants. In particular, the invention relates to microemulsions of crop protection agents with a combination of water-soluble active compounds and active compounds which are virtually insoluble in water, specifically microemulsions of glufosinate and oxyfluorfen or glyphosate and oxyfluorfen.
Frequently, combinations of active compounds are employed to use the properties of the individual active compounds jointly in the application, or else because the individual active compounds in the combination are synergistic, i.e. show super-additive increases in activity. Moreover, the active compounds are usually not employed as pure substances but, depending on the area of application and the desired physical properties of the application form, in combination with certain auxiliaries, i.e. they are “formulated”. In the case of a combination of active compounds of chemically different types, the person skilled in the art of formulation frequently encounters the problem of incompatibility of the individual active compounds with one another and with the auxiliaries in the joint formulation. To be able to make full use of the advantages of the combined active compounds, stable coformulations are of particular interest.
In principle, combinations of different active compounds can be formulated in various ways, depending on the prevalent biological and/or chemical-physical parameters. In general, suitable formulation possibilities in this context are, for example: wettable powders (WP), oil-in-water or water-in-oil emulsions (EW and EO, respectively), suspensions (SC), suspo-emulsions (SE) or else granules for soil application or application by scattering, or water-dispersible granules (WG). The abovementioned types of formulation are known in principle and described, for example, in: Winnacker-Küchler, “Chemische Technologie”, [Chemical Technology], Volume 7, C. Hauser-Verlag, Munich, 4th edition 1986; van Valkenburg, “Pesticides Formulations”, Marcel-Dekker N.Y., 1973; K. Martens, “Spray Drying Handbook”, 3rd Ed., 1979, G. Goodwin Ltd. London.
If the active compounds to be combined are compounds having contrasting chemical-physical properties, the formulation possibilities are naturally limited. Thus, for example, the broad-spectrum herbicides glufosinate and glyphosate, having phosphinoyl or phosphono groups, and their salts belong to the polar hydrophilic active compounds which dissolve relatively well in water. In contrast, herbicides from the group of the diphenyl ethers such as oxyfluorfen are virtually insoluble in water.
The combined use of herbicides of the abovementioned kind is already known. In DE-A-19501986 (WO 96122692, ZA-A-96/0502), for example, synergistic combinations of glufosinate-ammonium and salts thereof with oxyfluorfen are described, and wettable powders (WP), water-dispersible granules (WDG) and oil-in-water emulsions (EW) are mentioned as possible coformulations. Other coformulations of glufosinate-ammonium and oxyfluorfen are known from U.S. Pat. No. 5,324,708 and Research Disclosure 275 (1987), 154. In addition, the preparation of granules for such active compound combinations has been described; see EP-A-448538, EP-A-0394211.
Furthermore, for example aqueous dispersions with glufosinate or salts thereof and a water-insoluble herbicide are known (JP-A-07089817). In particular, aqueous dispersions with glufosinate-ammonium and linuron, monolinuron, metolachlor or alachlor (EP-A-0244754) or with glufosinate-ammonium and diuron or simazine (EP-A-0499798) are known.
Combinations of glyphosate(salts) and oxyfluorfen are known from WO 84/03607 and EP-A-0143547.
However, none of the abovementioned formulations is a microemulsion or comprises a microemulsion. In contrast to the milky-turbid macroemulsions and suspensions, microemulsions or micellar solutions are—owing to the small particle size (≦100 nm)—optically transparent. A particular advantage of the microemulsions consists in their thermodynamic stability, owing to which microemulsions have theoretically unlimited storage-stability and shelf-life. In contrast, macroemulsions or suspensions are usually only kinetically stable, and phase separation and thus “decomposition” of the formulation may occur after a period of time which differs, depending on the individual case.
Compared to the likewise optically transparent emulsion concentrates (EC), microemulsions have additionally generally a reduced percentage by weight of solvents. Furthermore, owing to the large reduction of the interfacial tension between the aqueous and the oil phase by the emulsifier systems in question, the otherwise widely used thickeners for stabilizing the formulation can be dispensed with. Since there is a correlation between interfacial and surface tension (see Young's equations), such micellar solutions additionally frequently do not require antifoams.
A further advantage of microemulsions is the fact that the very small oil or water droplets which are present in the concentrate are preserved or converted into stable macroemulsion droplets on dilution with water. Dilution with water, which is customary prior to biological application, therefore results in spray liquors having small particle sizes, thus preventing clogging of spray apparatus. Moreover, microemulsions can advantageously be prepared with very low energy input and with technically simple stirrers, i.e. even during the production advantages result compared to the abovementioned thermodynamically instable formulations, not only in terms of materials saved, but also in terms of reduced energy costs.
Examples of preparing pesticidal microemulsions are given, inter alia, in the publications WO-A-9006681, WO-A-9314630, EP-A-0160182, EP-A-0533057, EP-A-499587, EP-A-500401, EP-A-432062, DE-A-3624910, DE-A-3235612, EP-A-648414 and EP-A-617894.
However, the microemulsions in question contain neither glufosinate-ammonium nor glyphosate(salts), and the emulsifiers, wetting agents and dispersants disclosed in the abovementioned publications are in most cases unsuitable for preparing glufosinate—and/or glyphosate-containing microemulsions; their use results in instable formulations, characterized by strong turbidity and subsequent phase separation.
Furthermore, it is known that microemulsions with glyphosate(salts) and oxyfluorfen can be prepared using mixtures of fatty amine ethoxylates of various degrees of ethoxylation (GB-A-2267825) or of fatty amine ethoxylates and quaternized cationic surfactants (U.S. Pat. No. 5565409) in the presence of other surfactants or of compatibility agents. The emulsifiers mentioned in the publications are of an exclusively basic or cationic nature.
In addition to the abovementioned general advantages of microemulsions, it is also known, however, that microemulsions are “critical” systems insofar as they are usually sensitive toward variations in temperature and/or in exchange or in the addition of individual components. In most cases, a modification by addition of other surfactants is not possible, which makes an adaptation of the microemulsions to the active compounds and active compound combinations which are employed in each case or to other application conditions, such as the ratio of the active compounds, temperature variations during storage, climatic zones, etc., more difficult.
Hitherto, it is difficult to predict if stable microemulsions can be prepared for an individual case, and in most cases special coord
Maier Thomas
Würtz Jochen
Clardy S. Mark
Frommer & Lawrence & Haug LLP
Hoechst Schering AgrEvo GmbH
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