Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Reexamination Certificate
1998-02-27
2002-08-20
Levy, Neil S. (Department: 1616)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
C424S407000, C424S408000, C424S409000, C424S417000, C424S419000, C424S420000, C504S190000, C504S334000, C504S352000, C514S184000, C514S242000, C514S412000, C514S465000, C514S481000, C514S483000, C514S494000, C514S499000, C514S520000, C514S535000, C514S615000, C514S617000, C514S726000
Reexamination Certificate
active
06436421
ABSTRACT:
The present invention relates to pesticide compositions. In particular, the present invention relates to pesticide compositions comprising a pesticide and a redispersible polymer. The present invention also relates to a method for controlling agricultural pests by applying to the pest or the locus of the pest a pesticide composition comprising a pesticide and a redispersible polymer.
Compositions intended for the control of agricultural pests are typically applied by spraying a composition comprising the pesticide using water as a carrier liquid. For this reason, pesticide compositions are supplied to the grower in formulations which are intended to be dissolved or dispersed in water. These formulations may be liquid formulations such as aqueous solutions or emulsifiable concentrates or solid formulations such as wettable powders or granular formulations. Solid formulations have many advantages over liquid formulations in terms of cost, storage, and packaging, including disposal of packaging.
Biological efficacy of pesticides is influenced by many factors, particularly the residence time of the pesticide on the treated surface, which is often a plant leaf surface. A major factor influencing the residence time is the degree to which the pesticide resists wash-off by rain, that is, rainfastness. With liquid formulations, rainfastness may be improved by including ingredients in the formulation or adding such ingredients to the spray tank (tank mixing) that, during drying, provide a water-resistant bond between the pesticide and the substrate. For example, emulsified oil or water insoluble polymers prepared in emulsion have been used to improve liquid formulation rainfastness. One widely used material is a formulation comprising a carboxylated synthetic latex emulsion polymer, a primary aliphatic oxyalkylated alcohol, and water. This material has been shown to improve the efficacy of a variety of pesticides. However, because it is a liquid formulation, it cannot be used as a component of a solid pesticide formulation.
Solid formulations present a different set of competing problems when compared to liquid formulations. In order for solid formulations to readily disperse in water, water-resisting additives cannot be used in the formulation. In fact, high levels of water soluble dispersants are typically required so that the solid formulation will disperse in the spray tank. Although emulsified oil or water insoluble polymers prepared in emulsion have been used with liquid formulations or in tank mixes, none has been described that address the problem of improving rainfastness of solid formulations without requiring a separate tank mix additive. This is both inconvenient and problematic for the grower who desires to use a dry, solid pesticide formulation. Dry solid formulations are particularly important because they can be more easily stored, packaged, and transported than their liquid counterparts. Therefore, there is a continuing need for additives which are compatible with solid pesticide formulations.
We have discovered that redispersible polymers may be used as pesticide additives. Redispersible polymers are solid compositions which incorporate water insoluble polymers prepared in emulsion combined, prior to drying, with water soluble polymers. Such compositions are typically isolated by spray drying and the products are referred to as redispersible powders. The water soluble polymer is critical for redispersion of the water insoluble polymer. These polymers overcome many of the problems associated with the use of emulsion polymers as adjuvants in solid pesticide formulations. In addition, they provide a surprising increase in the efficacy of many pesticides and improved resistance to wash-off by rain.
Thus, this invention provides a pesticide composition, comprising:
(a) one or more pesticides; and
(b) one or more redispersible polymers comprising:
(1) one or more water insoluble polymers prepared in emulsion; and
(2) one or more water soluble polymers.
The composition may further comprise other ingredients to aid in dispersibility of the pesticide in water, modify surface tension of the spray, and promote adhesion of the water insoluble polymers.
The term “pesticide” means a chemical which is intended to mitigate a pest including insects, weeds, fungi, and related organisms. For purposes of this invention, a pesticide can also include viruses, bacteria, or other organisms which can control pests and which are found or can be modified to form a stable particle. The pesticide preferably comprises 5 to 90% by weight of the pesticide composition. The pesticide of the composition of this invention may be in the form of a pure active ingredient, a technical grade of the active ingredient, or an active ingredient formulated with one or more agronomically acceptable carriers. By “agronomically acceptable carrier” is meant any substance which can be used to aid the dispersion of the active ingredient in the composition in water without impairing the active ingredient's effectiveness and which by itself has no significant detrimental effect on the soil, equipment, desirable plants, or the agronomic environment. Pesticides in the form of particles are preferred. Most preferred are particles in the range of 0.1 to 20 microns in diameter.
The term “redispersible polymer” means a free-flowing dry powder comprising one or more water insoluble polymers and one or more water soluble polymers, produced by drying an emulsion polymer dispersion, that redisperses readily in water but, when dried a second time, forms a water resistant film. Redispersible polymers are well known in the art. See, for example, U.S. Pat. No. 3,784,648 (RE 28,780) (water insoluble synthetic resins with a water soluble condensation product of melamine and formaldehyde which contains sulfonate groups); U.S. Pat. No. 5,536,779 (polymer powder derived from unsaturated monomers and at least one added starch-degradation product); U.S. Pat. No. 5,519,084 (acrylic emulsion polymers and polyvinyl alcohol); DE 4,402,408 (unsaturated copolymers and post-added protective colloids); JP 7,053,730 (acrylic emulsion polymers and colloid prepared from sodium styrene sulfonate and a polymerizing emulsifying agent); EP 632096 (acrylic and vinyl emulsion polymers with amino functional polyvinyl alcohol); U.S. Pat. No. 5,252,704 (acrylic and vinyl emulsion polymers with polyvinyl pyrollidone); U.S. Pat. No. 5,225,478 (emulsion polymers of olefinically unsaturated monomers with water soluble metal salts of phenolsulfonic acid/formaldehyde condensates); and EP 723975 (emulsion copolymers of styrene and alkyl(meth)acrylates with water soluble colloids).
Many redispersible polymers are two-stage emulsion polymers formed when a second-stage, water soluble polymer forms a “shell” or coating around a discreet domain or “core” of the first-stage, water insoluble polymer. Examples of such core-shell polymers are disclosed in U.S. Pat. Nos. 4,916,171 and 5,403,894. In these examples, the water soluble polymer is a copolymer of methacrylic acid that is neutralized with base. U.S. Pat. No. 4,876,313 also discloses the use of polyfunctional compounds to partially graft or bond the water soluble and water insoluble polymers.
One embodiment of this invention provides a composition comprising a pesticide, formulated as a wettable powder, a dust, or a dispersible granule, and a redispersible powder comprising one or more water insoluble polymers prepared in emulsion and one or more water soluble polymers, such as those disclosed in the above references.
Another embodiment of this invention provides a wettable powder, a dust, or dispersible granule pesticide formulation comprising one or more pesticides and one or more redispersible polymers wherein the formulation is prepared by a process comprising the steps of:
a) combining a dispersion of the pesticide in water with one or more water insoluble polymers formed in emulsion and one or more water soluble polymers and
b) drying the combination.
Another embodiment of this invention provides a dry pesti
Guo Yili
Pierce Gregory C.
Quinn James Allen
Schindler Frederick James
?Rohm and Haas Company
Levy Neil S.
Rogerson Thomas D.
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