WO1993017554A1

WO1993017554A1 - Pesticidal concentrates having low volatility

Info

Publication number: WO1993017554A1
Application number: PCT/US1993/002069
Authority: WO
Inventors: Maria Garcia Ochomogo
Original assignee: Monsanto Company
Priority date: 1992-03-13
Filing date: 1993-03-12
Publication date: 1993-09-16

Abstract

A pesticidal formulation in concentrate form having low volatility is formed containing solid particulate bioactive in compounds and non-ionic surfactants, hydrocarbons having a viscosity of about 30 centipoise at 25 °C, silica and, optionally a polymeric oil-miscible thickener. The use of a large amount of organic solvents is avoided, therefore making the concentrate environmentally safe, easily storable, and providing a reduced fire hazard. The concentrate can be diluted with water and/or oil for use as a spray.

Description

PESTICIDAL CONCENTRATES HAVING LOW VOLATILITY

FIELD OF THE INVENTION

The present invention is directed to pesticidal concentrates with low volatility which 5 result in advantageous storage features, reduced health and fire hazards, allows high loading of solid active ingredient, and lower cost of formulation.

BACKGROUND OF THE INVENTION

Many pesticidally active compounds are sold

10 as emulsifiable concentrate (EC) formulations in which the active ingredient is dissolved in an organic solvent with appropriate surfactants. When the concentrate is mixed with water the active ingredient becomes dispersed in an emulsion.

15 However, since the organic solvent is a primary ingredient of the emulsion, such formulations must be stored under special conditions, related to the flashpoint and fire hazard of the organic chemicals and to the volatility of the organic solvent as a

20 health risk.

The present invention provides an advantageous concentrate wherein most of the organic ingredients, and in particular the organic solvent,

** are minimized. This results in formulations which are

25 less hazardous to the environment, are less irritating to the users, have higher flashpoints, and unexpectedly, allow for a high load of solid active ingredient. Furthermore, the present invention provides an advantage in that the concentrate can be dispersed in large volumes of either water or oil.

It is therefore an object of the present invention to provide pesticidal concentrates which have improved storage characteristics and reduced health and fire hazards.

It is yet a further object of the present invention to provide improved pesticidal concentrates which are dilutable in either water or oil.

It is yet another object of the present invention to provide pesticidal concentrates which are unexpectedly stable and exhibit improved loading of solid active compounds. These and other objects will be apparent from the following description and from practice of the invention.

SUMMARY OF THE INVENTION

The present invention provides a pesticidal formulation in concentrate form comprising about 5 - 20 % by weight of non-ionic surfactants containing hydrophobic and hydrophilic groups; about 1 to 45 % by weight biologically active particulate compounds having an average particle diameter of less than about 5 microns; about 5 to 40 % by weight of a hydrocarbon characterized by a viscosity of less than about 30 centipoise at 25°C; up to about 3 % by weight hydrophobic silica, preferably up to about .08 % by weight of a polymeric oil-miscible thickener; and water. This formulation can be stabilized between pH 2 and pH 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The non-ionic surfactants which may be utilized in the formulation of the present invention are those which have a hydrophile-lipophile balance (HLB) of at least about 7 and preferables less than about 12. Preferred surfactants are polyoxyethylene- polyoxypropylene copolymers and in particular those sold under the trade name Pluronic™. The concentrate according to the present invention will contain about 5 to 20 % by weight of such non-ionic surfactants. A preferred range is 5 to 10 % by weight of non-ionic surfactants.

The bioactive compounds utilized in the concentrate will be solids, milled to an average particle size (diameter) of about 5 microns or less. Typical bioactive compounds include the pesticide N,N-[1,4-piperazinediyl-bis-(2,2,2- trichloroethylidene) ]-bis-[formamide] , commonly known as triforine. Other pesticides include, but are not limited to: Herbicides

Dimethyl tetrachloroterephthalate (Dacthal)

Ethyl-2-[4-(6 chloroguinoxalin -2-yloxy) phenoxy] propionate. (Assure)

3-(1-methylethyl)-1(H)-2,1,3-benzothiadiazin- 4(3H)-one 2,2-dioxide (bentazone, BASAGRAN)

3-5-dibromo-4-hydroxybenzonitrile (bromoxynil) 3-amino-2,5-dichlorobenzoic acid (chloramben, AMIBEN)

3,6-dichloro-2-pyridinecarboxylic acid (clopyralid, LONTREL)

2-[1-(ethoxyimino)butyl]-3-hydroxy-5- (tetrahydro-2H-thiopyran-3-yl)-2-cyclohexene- 1-one (cycloxydim)

Ethyl 2 [[[[(4-chloro-6-methoxypyrimidin-2- yl) amino] carbonyl] amino] sulfonyl] benzoate (sulfonyl urea, Classic) methyl sulfanilylcarba ate (Asulam)

2-[4,5-dihydro-4-methyl-4-(1-methyethyl)-5- oxo-lH-imidazol-2-yl]-3-quinolinecarboxylic acid (imazaquin, SCEPTER) 3-(3,4-dichlorophenyl)-l-methoxy-l- methylurea. (Linuron)

3,5-dinitro-N4, N4-dipropyl sulfanilamide (SurfIan) (2-chloro-4-ethyl-amino-6-isopropylamino-5- triazine) (Atrazine) α,α,α - trifluoro-2,6-dinitro-N,N-dipropyl-p- toluidine (Trifluralin)

Fungicides 5,6-dihydro-2-methyl-N-phenyl-l,4-oxathiin— 3-carboxamide 4,4-dioxide (oxycarboxin)

N-trichloromethylthio-4-cyclohexene-l,2- dicarboximide (captan)

5-butyl-2-(dimethylamino)-6-methyl-4(1H)- pyrimidinone (dimethirimol)

Insecticides dimethyl N,N - (thiobis (methylimino) . carbonyloxy)bis(ethanimidothioate) (thiodicarb) 2,2-dimethyϊ-l,3 henzodioxal-4-yl methyl carbamate (Bendiocarb)

Hexakis (2-methyl-2 phenylpropy1)- distannoxane (vendex)

(1-naphthyl N-methylcarbamate) (Carbanyl) IGR

Ethyl (2-[4-phenoxy phenoxy-] ethyl) carbamate (Fenoxycarb)

PGR

Butanedioic acid mono (2,2-dimethyl hydrazide) (Daminozide)

N- [(acetylamino) methyl) ]-2-chlor-N-(2,6-di- ethyl-phenyl) acetamide (Limit)

-Preferably, the solid bioactive compound will have a melting point greater than about 40° C. The particle size of the solid material which is used in the concentrate according to the present invention is important since there is no organic solvent per se utilized in the formulation, and therefore the solids will be essentially insoluble. In order to effect stability of the solids, therefore, the particle size must be relatively small in order to remain suspended within the viscous oil.

The hydrocarbons utilized in the composition of the present invention are preferably liquid paraffinic oils and other oils having viscosities less than about 30 centipoise at 25° C. Examples of such oils are soybean oil, aromatic hydrocarbons of greater than about 8 carbon atoms, and Chevron® 10ON. The composition will contain about 5 to 40 % by weight, and preferably about 15 to 30 % by weight of the hydrocarbon.

The silica used is preferably a hydrophobic high surface area silica such as fumed silica, an example of which is a commercial product Degussa™ R.972. The composition will contain from about 0.5 to 3 % by weight of the silica and preferably about 0.5 to 1 % by weight.

A small amount of a polymeric oil thickener is also desirable, usually present in amounts of about 0.03 to 0.10 % by weight and more preferably 0.05 to 0.08 % by weight. Typical polymeric oil thickeners are ethoxylated castor oil such as those typically sold by N Chemicals or known under the trade name Thixin R. The concentrate will typically contain about 1 to 45 % by weight of the bioactive compound and preferably about 15 to 40 % by weight of the bioactive compound. The concentration of bioactive compound for a given formulation will be that which can be conveniently diluted by the user to be administered in effective dosages for the given active compound. The formulation according to the present invention is a dispersion of an oil phase, entrapping the solid bioactive particle in a continuous aqueous phase. It is advantageous that this concentrate can be diluted with water, oil or both. Typical dilutions of the concentrates are 1:100 to 1:1000. Once diluted the resulting formulation is suitable for agricultural spraying, is stable over a wide temperature range, and may be easily cleaned from their packages and containers. Due to the minimal use of organic solvents, the formulations are usually non-irritants to the eyes and skin, and have flashpoints of over about 200° F.

The concentrates according to the present invention are typically characterized by room temperature viscosity between about 400 to 800 cps and will contain between around 50 to 350 grams/liter of solid biologically active compound. This is an advantageously high loading of the active compound as compared with other types of emulsifiable concentrate formulations of the same viscosity.

The present invention also provides a process for preparing a low volatility pesticidal concentrate which comprises the formation of a first pre-mixture by agitating together silica, hydrocarbon oil and the polymeric oil-miscible thickener, if present, and heating to about 50° C for several minutes (usually up to about 15 minutes is sufficient) to form a uniform mixture. A second pre-mixture is formed by blending the surfactants in approximately 1/2 of the water to be utilized. The aqueous mixture is warmed until the surfactants are evenly dispersed. A third pre-mixture is formed by adding the bioactive compound to the remaining water and stirring to uniform consistency. The second pre-mixture containing the surfactants is added to the third pre- mixture and mixed until a uniform mixture is provided. Finally, the first pre-mixture containing the silica, oil thickener and hydrocarbon is added slowly until an emulsion is formed with mixing.

Having described the preferred embodiments of the invention the following examples are provided by way of illustration but are not intended to limit the invention in any way. Example 1

Ingredient Percentage/wt Triforine 20.20% (19.6%) Aerosil R-972 (fumed silica) 0.95%

Thixin R' 0.07%

Chevron 100 N Oil 25.98%

Pluronic P104 1.00% Pluronic L92 5.00%

Pluronic R25R4 2.00%

Water 44.80%

Total 100%

A premix A of Thixin R, Aerosil R-972 and Chevron 100N oil is first made by heating to 50 % C for 15 minutes. Separately a pre-mix B is made by blending the pluronic surfactants in 1/2 the water. Warm the pre-mix gently until surfactants are dispersed in the water. Then, to the rest of the water add the triforine by mixing _* .h a mechanical agitator at 4000 rpm for 5 minutes. Add the pre-mix B and continue mixing at 4000 rpm. At last, add the pre- mix A slowly until the emulsion is formed. Mix at 8000 rpm for 15 minutes. The resulting formulation was stable and white in color.

Example 2

Ingredient

Triforine (97%) Aerosil R-972 Thixin R

Chevron 100 N Oil Pluronic P104 Pluronic L92 Pluronic R25R4 Water

Total

The formulation is identically prepared as Example 1. The resulting formulation was stable and white in color. The viscosity of this formulation was lower than Example 1.

Example 3

A formulation was prepared as in Example 1 except that the surfactant Pluronic R25R4 was eliminated and the Pluronic L92 was increased to 7.00 %. The resulting formation was stable and white in color. The viscosity was higher than Example l.

Example 4

A formulation was prepared as in Example l except that the Chevron 100 N oil was substituted by soybean oil. The resulting formulation was similar to Example 1.

Example 5

A formulation was prepared as Example 1 except using an organoborane as the active ingredient. The resulting formulation was a stable white opaque emulsion.

Example 6 A formulation was prepared as Example 1 except that a C-10 aromatic hydrocarbon was used instead of Chevron 100 N oil. The resulting formulation was a stable white opaque emulsion.

Example 7

A formulation was prepared as Example 1 except the triforine to was increased 25 % a.i. The resulting formulation was a stable white opaque emulsion.

Claims

WHAT IS CLAIMED IS:

1. A pesticidal formulation in concentrate form being an emulsion comprising:

(a) about 5 to 20 % by weight of non-ionic surfactants having an HLB of at least about 7;

(b) about 1 to 45 % by weight of a solid biologically active particulate compound of average particle diameter of less than about 5 microns;

(c) about 5 to 40 % by weight of a hydrocarbon characterized by viscosity of less than about 30 centipose at 25° C;

(d) up to about 3 % by weight of silica; and

(e) water.

2. The composition according to claim 1 further comprising up to about .08 % by weight of a polymeric oil-miscible thickener.

3. A composition according to claim 1 wherein said non-ionic surfactants comprise about 5 to 10 weight percent of said composition.

4. A composition according to claim l wherein said biologically active compound comprises about 15 to 40 % by weight of said composition.

5. A composition according to claim 1 wherein said hydrocarbon comprises about 15 to 30 weight percent of said composition.

6. A composition according to claim 1 wherein said silica comprises about 0.5 to 1 % by weight of said composition. __l _

7. A composition according to claim 2 wherein said polymeric oil miscible thickener comprises about 0.05 to 0.08 weight percent of said composition.

8. A composition according to claim 1 or 4 wherein said bioactive compound comprises N-^ N-[l,4- piperazinediy 1-bis-(2,2,2-trichloroethylidene) ]-bis- [formamide] .

9. A composition according to claim 1 or 6 wherein said silica comprises fumed silica.

10. A composition according to claim 1 or 2 wherein said polymeric oil miscible thickener comprises ethoxylated castor oil.

11. A composition according to claim 1 or 5 wherein said hydrocarbon comprises paraffinic oil.

12. A composition according to claim 1 or 3 wherein said non-ionic surfactants comprise polyoxyethylene-polyoxypropylene copolymers.

13. A method for preparing a bioactive formulation in concentrate form wherein said composition comprises 5 to 20 weight percent of non- ionic surfactants containing hydrophilic and hydrophobic groups; 1 to 40 % by weight of biologically active solid particulate compounds having average particle diameter of less than about 5 microns; 5 to 40 % by weight of hydrocarbons characterized by viscosity of less than about 30 centipoise at 25° C; up to about 3 % by weight of silica; up to .08 % by weight of polymeric oil- miscible thickener; and water; forming a first pre-mixture comprising said polymeric oil-miscible thickener, silica and hydrocarbons by mixing said three ingredients at a temperature up to about 50° C until a uniform pre- mixture is formed; forming a second pre-mixture comprising said non-ionic surfactants and a portion of said water; forming a third pre-mixture formed by agitating said bioactive compound in the remaining water; adding said second pre-mixture to said third pre-mixture; adding said first pre-mixture to the resulting mixture.