Plant protecting and regulating compositions – Plant growth regulating compositions – Organic active compound containing
Reexamination Certificate
2000-10-27
2003-04-01
Pryor, Alton N (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Organic active compound containing
C504S116100, C504S118000, C504S141000
Reexamination Certificate
active
06541425
ABSTRACT:
The present invention relates to a solid formulation of a crop protection product with delayed release of the active ingredient, obtainable by preparing a melt comprising:
0.1-80% by wt. of an active ingredient which can be used in crop protection, or of a combination of such active ingredients,
10-80% by wt. of at least one mineral filler,
0-20% by wt. of inorganic or organic additives, and
to 100% by wt. of at least one thermoplastic water-insoluble polymer,
the total of all constituents equaling 100% by weight, and subsequent shaping.
The invention furthermore relates to a process for the preparation of a solid formulation of a crop protection product, which comprises melting at least one active ingredient, at least one mineral filler and, if appropriate, inorganic or organic additives with at least one thermoplastic, water-insoluble polymer (solubility<100 mg per 1 of water at 20° C.) in an extruder to give a thermoplastic mixture and subsequently subjecting this mixture to shaping, either in the hot or cold state.
The invention furthermore relates to a process which comprises using in solid form such a solid formulation of a crop protection product for controlling phytopathogenic fungi, undesired vegetation, undesired attack by insects or mites, and/or for regulating plant growth, and allowing it to act on plants, their environment or on seed. Such solid formulations furthermore release the active ingredient(s) which it comprises in a controlled and slow manner (complete release within several days up to some months) into the environment (soil, aqueous medium, plants). This leads to a biological availability over a prolonged period to suit the respective purpose. For example, this is necessary for active ingredients which are insufficiently persistent in soil and/or plant, for active ingredients which are phytotoxic to the crop plant, or else for applications where it is required that the availability or release of active ingredient extends over a prolonged period.
Formulations comprising active ingredient which are prepared by melt extrusion are generally known. Extruding and subsequent shaping of melts of water-soluble polymers, preferably copolymers of vinylpyrrolidone, which contain active ingredient are described in EP-A 240904 and EP-A 240906.
WO 94/08455 describes the coextrusion of crop protection products with polyvinylpyrrolidone and subsequent cooling, crushing and grinding. The ground extrudate disperses rapidly and finely in water and is suitable for spray applications.
There are furthermore known solid formulations of crop protection products which are prepared by melt extrusion with subsequent shaping and which allow a controlled, slow release of pesticides.
WO 91/03940 describes biodegradable pesticide-comprising matrices, their preparation by means of melt extrusion with subsequent shaping, and their use for the controlled release of pesticides. In addition to synthetic polymers (<25%, mainly ethylene/vinyl acetate copolymers), starch and starch derivatives are subjected to melt extrusion together with the respective active substances (carbosulfan inter alia) with addition of water and glycerol to give the matrix. Depending on the formula, the matrices release the active ingredients in water within weeks or months.
WO 95/28835 describes the preparation of agrochemical formulations with hydrophobic and hydrophilic waxes. Active ingredient, carnauba wax and polyethylene glycol are subjected to melt extrusion, ground and graded. The 500-1000 &mgr;m fraction is released in water. Depending on the composition, 14-100% of the active ingredients are released after 10 hours.
U.S. Pat. No. 5,643,590 describes insecticidal compositions whose mammalian toxicity is markedly reduced. In a multi-step process, pesticides together with PVC, stabilizer, plasticizer and mineral additive are mixed intimately at 75-110° C., and the mixture is cooled to 70° C., transferred into an extruder, extruded at 150-180° C. and subsequently pelleted. The pellets, which do not dust, exhibit a markedly reduced toxicity to mammals and a prolonged activity (100% worm control over 10 weeks).
DE 19 622 355 describes the preparation by melt extrusion and injection molding of shaped articles which exhibit controlled release. The crop protection agent—together with a vinyl acetate polymer which is insoluble in water and a water-soluble polymer (polyvinyl acetate/vinylpyrrolidone)—is subjected to melt extrusion and granulation.
Formulations based on synthetic polymers and starch (WO 91/03940) can be plastified homogeneously and granulated to give dust-free granules in a simple manner—i.e., inter alia, without addition of water and/or glycerol—only if the polymer content is high (>60%) and rapidly show signs of decomposition since the starch is sensitive to heat and shearing forces. Also, such formulations swell and exhibit low density and thus only show insufficient sedimentation in water or soils flooded with water.
While formulations based on hydrophobic and hydrophilic waxes (WO 95/28835) are easy to prepare by simply melting them together with the active ingredient, they are not easy to process (for example extrusion granulation, hot cutting) and are not dimensionally stable upon heat aging (14 days at 54° C.) as a result of the wax-like consistency. Moreover, formulations made of stearic acid or stearyl alcohol and PEG do not sediment in water (density<1 g/ml).
U.S. Pat. No. 5,643,590 describes a complicated multi-step process in which pesticides are mixed intimately at 75-110° C. with PVC, stabilizer, plasticizer and mineral additive, the mixture is cooled to 70° C., transferred into an extruder and extruded at 150-180° C., and the extrudate is subsequently pelleted. The lack of thermal stability of a large number of active ingredients does not allow high temperature stress because of the danger of decomposition. Moreover, the manufacturing process should be as simple as possible.
In DE 19 622 355, crop protection agents are subjected to melt extrusion and granulation together with a vinyl acetate polymer which is insoluble in water and a water-soluble polymer (polyvinyl acetate/vinylpyrrolidone). Due to low glass transition temperatures, formulations based on polyvinyl acetate polymers exhibit insufficient heat resistance. Upon heat aging (14 days at 54° C.), granulated melt extrudates made of polyvinyl acetate and polyvinylpyrrolidone coalesce to form a coherent mass.
The problems are insufficient heat and storage stability, inadequate sedimentation, poor granulation properties, inadequate homogeneity of the melt, and complicated and expensive production.
It is an object of the present invention to provide a solid, storage-stable, slow-releasing crop protection formulation which settles in water, can be granulated and can be prepared readily from inexpensive components by subjecting a mixture of solids to melt extrusion, followed by shaping.
We have found that this object is achieved by the composition described at the outset and the process for its preparation.
In general, suitable active ingredients are those which do not undergo decomposition under the processing temperatures when preparing the melt. Preferred substances are those which are solid at room temperature since these are easier to mix and meter. However, the use is not restricted to solid active ingredients since even liquid active ingredients can be processed by means of a solid matrix to give a solid, heat-resistant and storage-stable formulation.
The amount of active ingredient components in the total formulation may vary within wide limits, depending on efficacy, release rate and processability. Thus, the active ingredient content may range from 0.1-80% by weight, preferably from 0.5-40% by weight, especially preferably from 1-20% by weight, based on the total formulation. The only condition is that the formulation is still thermoplastically processable.
Crop protection agents which may be mentioned are fungicides, herbicides, insecticides and growth regulators. Combinations are also possible.
The following
Bratz Matthias
Ernst Andreas
Kessler Thomas
Lange Armin
Schelberger Klaus
BASF - Aktiengesellschaft
Keil & Weinkauf
Pryor Alton N
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