Stable high strength oil-in-water emulsions

Abstract

Novel high-strength herbicidal oil-in-water emulsions containing a water soluble salt of glyphosate and an oil soluble herbicide active ingredient show enhanced stability to oil phase coalescence and active ingredient crystallization by the use of specific surfactants and water immiscible organic solvents.

1 . A stable high-strength herbicidal oil-in-water emulsion composition comprising:
 a) a discontinuous oil phase comprising, with respect to the oil-in-water emulsion, from about 25 grams active ingredient per liter (g ai/L) to about 300 g ai/L of at least one oil soluble herbicide active ingredient and from 0 grams per liter (g/L) to about 300 g/L of a water immiscible organic solvent;   b) a continuous aqueous phase comprising, with respect to the oil-in-water emulsion, from about 260 g ai/L to about 570 g ai /L of a water soluble salt of glyphosate and from about 200 g/L to about 500 g/L of water; and   c) at least two non-ionic EO/PO block copolymer emulsifying surfactants with at least one having a hydrophile lipophile balance (HLB) value of about 13 to about 16 and at least one having an HLB value of about 22 to about 29 and with each having a molecular weight (mw) of about 5000 or higher, with the combined emulsifying surfactants comprising, with respect to the oil-in-water emulsion, from about 1 g/L to about 200 g/L.   
     
     
         2 . The composition of  claim 1 , wherein the at least one oil soluble herbicide active ingredients is a synthetic auxin or a lipid synthesis inhibitor herbicide. 
     
     
         3 . The composition of  claim 1 , wherein the at least one oil soluble herbicide active ingredient has a water solubility of less than about 3000 parts per million (ppm). 
     
     
         4 . The composition of  claim 1 , wherein the water immiscible organic solvent has a water solubility of less than about 1000 ppm. 
     
     
         5 . The composition of  claim 1 , wherein the discontinuous oil phase includes from 0 grams per liter (g/L) to about 300 g/L of a water immiscible organic solvent. 
     
     
         6 . The composition of  claim 1 , wherein the discontinuous oil phase further includes an emulsion stabilizer. 
     
     
         7 . The composition of  claim 1 , wherein the continuous oil phase includes from about 200 g/L to about 400 g/L of water. 
     
     
         8 . The composition of  claim 1 , wherein the continuous oil phase includes a water soluble salt of glyphosate. 
     
     
         9 . The composition of  claim 8 , wherein the water soluble salt of glyphosate is an organo ammonium salt or a potassium salt. 
     
     
         10 . The composition of  claim 8 , wherein the organo ammonium salt is a dimethyl ammonium, a isopropyl ammonium, a monoethanol ammonium, or a N,N,N,N-trimethylethanol ammonium (choline) salt. 
     
     
         11 . The composition of  claim 8 , wherein the continuous aqueous phase includes about 260 g ai/L to about 450 g ai/L of the water soluble salt of glyphosate. 
     
     
         12 . The composition of  claim 1 , wherein the at least two non-ionic EO/PO block copolymer emulsifying surfactants include both di- and tri-block co-polymers of ethylene oxide (E0) and propylene oxide (PO). 
     
     
         13 . The composition of  claim 1 , wherein the combined emulsifying surfactants comprise, with respect to the oil-in-water emulsion, about 1 g/L to about 100 g/L. 
     
     
         14 . The composition of  claim 1 , further including additional water soluble herbicide active ingredients. 
     
     
         15 . The composition of  claim 1 , wherein the composition forms a stable, homogeneous emulsion that does not exhibit coalescence under the storage conditions. 
     
     
         16 . The composition of  claim 1 , wherein the composition is stable at temperatures of greater than or equal to about 40° C. for a period of at least 4 weeks. 
     
     
         17 . The composition of  claim 1 , wherein the composition does not exhibit separation or precipitation (or crystallization) of any of the components at temperatures below about 20° C. 
     
     
         18 . The composition of  claim 1 , wherein the discontinuous oil phase comprises fluroxypyr-meptyl and naphthalene depleted Aromatic 150 fluid, and the continuous aqueous phase comprises glyphosate dimethyl ammonium and water. 
     
     
         19 . A method of preparing a stable high-strength herbicidal oil-in-water emulsion composition comprising:
 a) preparing a discontinuous oil phase comprising, with respect to the oil-in-water emulsion, from about 25 grams active ingredient per liter (g ai/L) to about 300 g ai/L of at least one oil soluble herbicide active ingredient and from 0 grams per liter (g/L) to about 300 g/L of a water immiscible organic solvent;   b) preparing a continuous aqueous phase comprising, with respect to the oil-in-water emulsion, from about 260 g ai/L to about 570 g ai /L of a water soluble salt of glyphosate and from about 200 g/L to about 500 g/L of water, and at least two non-ionic EO/PO block copolymer emulsifying surfactants with at least one having a hydrophile lipophile balance (HLB) value of about 13 to about 16 and at least one having an HLB value of about 22 to about 29 and with each having a molecular weight (mw) of about 5000 or higher, with the combined emulsifying surfactants comprising, with respect to the oil-in-water emulsion, from about 1 g/L to about 200 g/L; and   c) adding the oil phase into the aqueous phase under high shear homogenization until an emulsion is achieved.   
     
     
         20 . The method of preparing the stable high-strength herbicidal oil-in-water emulsion composition of  claim 19 , wherein the emulsion droplet size is between 0.1 μm and 5 μm.