Water-based microemulsion of a pyrethroid

Details Water-based microemulsion of a pyrethroid Water-based microemulsion of a pyrethroid

2000-04-04

2001-06-26

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

C424S406000, C424S078170, C424S078180, C424S078310, C514S772100, C514S772400, C514S772700, C514S784000, C514S785000, C514S937000, C514S941000, C514S943000

Reexamination Certificate

active

06251416

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a delivery system for agriculturally active chemicals, and, more particularly, to a clear, one-phase, efficacious aqueous microemulsion for delivering a pyrethroid insecticide at a high loading.
2. Description of the Prior Art
Agriculturally active chemicals are most preferably applied in the form of aqueous emulsions, solutions or suspensions. Occasionally, they may also be applied in the form of a dust wherein the active ingredient is adsorbed onto or mixed with a finely divided inert carrier material, such as, china clay, or the like. With such powdered or dust compositions, drift due to wind is a problem and consequently, liquid formulations are preferred.
One of the problems with such liquid formulations is the fact that chemicals having agricultural activity often exhibit extreme insolubility in water. This results in their having to be dissolved either in organic solvents or utilized in the form of emulsions or suspensions. With respect to the use of organic solvents, these are generally disadvantageous from an environmental and cost viewpoint. Particularly, such organic chemicals may exhibit toxicity or side-effects which may be adverse to the effect of the agricultural chemical itself or to the subsequent fruit or vegetable produced in the particular agricultural use. This toxicity may also be disadvantageous with respect to handling.
When attempts are made to provide emulsified or suspension formulations, difficulties are encountered with respect to providing a desirably high concentration of the agriculturally active ingredient. Thus, when such agriculturally active chemicals are formulated into a macroemulsion (sometimes referred to herein as an emulsion), it is difficult to maintain the emulsified state. This, in turn, creates problems in maintaining a uniform formulation, particularly, when the formulation is diluted with water for application to the plants.
U.S. Pat. No. 5,317,042 disclosed a clear stable, efficacious aqueous microemulsion of a pyrethroid insecticide, alone, or in a complex mixture, obtained by mixing the insecticide with an inert matrix composition containing a defined mixture of nonionic surfactant to form a microemulsion concentrate, and diluting with water. The inert matrix composition consisted of a predetermined mixture of nonionic surfactants which also included nonylphenol ethoxylate with HLB>6. However, the presence of nonylphenol ethoxylate in the formulation may be considered detrimental in some cases.
It is also desired to provide an aqueous microemulsion a pyrethroid insecticide which is free of nonylphenol ethoxylate, and which is stable upon formation, and which can be used within a relatively long time, without significant hydrolysis or precipitation.
SUMMARY OF THE INVENTION
What is provided herein is a clear, one-phase, efficacious aqueous microemulsion of an agriculturally active pyrethroid insecticide, which is free of nonylphenol ethoxylate, and which comprises, by weight:
(a) about 0.0005-5%, preferably 0.01-3% of said pyrethroid,
(b) about 0-6%, preferably 0.015-4%, of N- C
1
-C
4
alkyl pyrrolidone, preferably N-methyl pyrrolidone,
(c) about 0.0002-4%, preferably 0.005-2%, of a C
6
-C
18
a alkyl pyrrolidone, preferably N-octyl pyrrolidone,
(d) 0-3%, preferably 0.05-1.5%, of an EO/PO block copolymer surfactant,
(e) 0.003-10%, preferably 0.04-6%, of an ethoxylated castor oil or a tristyryl phenol ethoxylate, and
(f) 0-1%, preferably 0.0005-0.6% of a phosphate ester as a pH buffer,
(g) at least about 80% of water, preferably 90-99.99%.
DETAILED DESCRIPTION OF THE INVENTION
Surfactant Trade Names
Pluronic® L31-EO/PO block copolymer surfactants, BASF
Igepal® CO-630-Nonylphenol ethoxylate, Rhone-Poulenc
Soprophor® BSU-Tristyrylphenol ethoxylate, Rhone-Poulenc
Soprophor® 3D-33-Tristyrylphenol ethoxylate phosphate ester, Rhone-Poulenc
Alkamuls® EL 620-Ethoxylated Castor Oil, Rhone-Poulenc
Gafac® RE-610-Nonylphenol ethoxylate phosphate ester, Rhone-Poulenc
Rhodafac® RA 600-Linear ethoxylate phosphate ester, Rhone-Poulenc
Rhodafac® RS 710-Branched ethoxylate phosphate ester, 9.75 E.O., Rhone-Poulenc
A pyrethroid is a class of well known and widely-used insecticides of which cypermethrin, o-allethrin, permethrin, piperonyl butoxide and tetramethrin are representative examples. In accordance with the invention a clear, efficacious, aqueous, microemulsion of a pyrethroid was formulated having the following components, in parts by weight.
TABLE 1
AQUEOUS MICROEMULSION COMPOSITION
OF THE INVENTION
Amounts (% by Wt.)
Component
Suitable
Preferred
(a)
Pyrethroid
0.0005-4
0.010-3
e.g. cypermethrin
(b)
C
1
-C
4
alkyl pyrrolidone
   0-6
0.015-4
e.g. N-methyl pyrrolidone
(c)
C
6
-C
18
alkyl pyrrolidone,
0.0002-4
0.005-2
e.g. octyl pyrrolidone
(d)
EO/PO block copolymer
   0-3
 0.05-1.5
e.g. Pluronic ® L31
(e)
Ethoxylate of Castor Oil
 0.003-10
 0.04-6
or tristyryl phenol
ethoxylate, e.g.
Alkamuls ® EL-620
or Soprophor ® BSU
(f)
Phosphate ester, e.g.
  0-1%
  0.005-0.6%
Soprophor ® 3D-33,
Rhodafac ® RS 710 or
Rhodafac ® RA 600
(8)
Water
>80
    90-99.99
100.0
100.0
This composition is a stable, one-phase, efficacious microemulsion of pH<4 at ambient temperatures free of nonylphenol ethoxylate and which is designed for use after preparation.
Other agricultural active chemicals which may be included in the compositions of the invention are: permethrin; permethrin+Kathon®, D-allethrin; tetramethrin; deltamethrin; piperonyl butoxide; mixed pyrethroids; dicofol; tefluthrin; resmethrin; phenothrin; kadethrin; bifenthrin; cyhalothrin; cycloprothrin; tralomethrin; cyfluthrin; fenvalerate and isomers; fenpropathrin; fluvalenate; rotenone; biphenyl compounds like, methoxychlor; chlorbenzilate; bromopropylate and chlorfenethol.


REFERENCES:
patent: 5427794 (1995-06-01), Miles

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