Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Reexamination Certificate
1997-10-27
2001-06-26
Levy, Neil S. (Department: 1617)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
C514S786000, C514S789000, C514S937000, C514S939000, C514S970000
Reexamination Certificate
active
06251415
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the general field of formulations of pesticides. In particular it relates to the development of a unique combination of solvents that affords more concentrated solutions of a number of pesticidally active materials, especially pyrethroids such as permethrin, cypermethrin, zetacypermethrin, and bifenthrin, than were previously available in solvents suitable for the preparation of emulsifiable concentrates for agricultural, domestic, and horticultural use. The solvent combination has the added advantage of low odor, low viscosity at reduced temperatures, and a high flash point. The use of this combination of solvents to provide concentrated solutions of pesticides is heretofore unknown. Compositions of the same solvents are also useful for the preparation of microemulsions of pesticides.
SUMMARY OF INVENTION
For the purposes of this application an emulsifiable concentrate (EC) formulation is a concentrated solution of a pesticide in an organic solvent that contains suitable surfactants, including emulsifiers, so that when mixed with a relatively large volume of water it will give a stable oil-in-water emulsion for application, as by spraying, to the target site. The requirements for a satisfactory EC formulation are: chemical stability (no loss of active ingredient during storage); physical stability (no phase separation over the range of temperatures likely to be encountered during storage); high flashpoint (for safe warehouse storage); and low viscosity (for ease of mixing with water for application). If the formulation is to be used or marketed in the United States, it is essential that it be accepted for registration by the Environmental Protection Agency (EPA).
For the purposes of this application a microemulsion (ME) formulation is an emulsion of a small amount of a pesticide solution in an organic solvent in a relatively large volume of water, yielding a concentration of the pesticide ready for application to the target site. The microemulsion will be formed through the use of suitable surfactants, including an amount of emulsifier substantially greater relative to the amount of pesticide than in EC formulations. The resulting emulsion droplets are so small that the microemulsion formulation is optically clear, rather than milky in appearance. Some microemulsions, although ready for use as prepared, retain microemulsion characteristics such as optical clarity upon further dilution with water. The requirements for a satisfactory ME formulation are chemical and physical stability. Again, registration with the Environmental Protection Agency (EPA) is essential, if the formulation is to be used or marketed in the United States.
The studies that led to the development of the novel combination of solvents of this invention were motivated by the desire to improve EPA-approved emulsifiable concentrates containing e.g. from 2 to 3.2 pounds of pyrethroid per gallon of formulation. While these products have been marketed and used successfully, at the low temperatures encountered in some storage facilities the EC formulations undergoes phase separation, including the formation of crystals.
A number of solvents and solvent combinations were investigated for solving the storage stability problem noted above, but a combination of three solvents has now been found to provide excellent results. The three solvents used in this combination are:
glyceryl triacetate, available from Eastman Chemical Products, Inc. as Kodaflex® Triacetin Plasticizer (hereafter called Triacetin);
a hydrotreated light petroleum distillate consisting predominantly of C
12
to C
15
isoparafinic hydrocarbons available e.g. from Exxon Company as Isopar M (hereafter called Isopar M);
bis(-methylethyl)-1,1′-biphenyl available from Ridge Technologies, Inc. as NuSOlv™ ABP-103, (hereafter called ABP-103).
The preferred solvent system is made up of 15 to 32 wt. % Triacetin, 15 to 32 wt. % Isopar M, and 40 to 55 wt. % ABP-103.
REFERENCES:
patent: 1707465 (1929-04-01), Volck
patent: 4871766 (1989-10-01), Tguda et al.
patent: 5160528 (1992-11-01), Chaudhuri et al.
patent: 5707638 (1998-01-01), Lösel et al.
patent: 5792465 (1998-08-01), Hagarty
FMC Corporation
FMC Corporation
Levy Neil S.
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