GLYPHOSATE-AMMONIUM SULFATE HERBICIDAL FORMULATION

Abstract: A shelf-stable aqueous concentrate herbicidal formulation containing glyphosate, ammonium sulfate and a quaternary ammonium salt.

Description: Field of the Invention This invention relates to a novel aqueous concentrate herbicidal formulation containing both glyphosate and ammonium sulfate. Description of the Prior Art Glyphosate (N-phosphonomethylglycine) is well-known in the art as an effective herbicide. It is known in the art that glyphosate, which is an organic acid, is relatively insoluble in water. Therefore, glyphosate is normally formulated and applied as a water-soluble salt, especially as the isopropylamine salt (IPA salt). Various formulations of glyphosate are disclosed in U.S. Patents 4,405,531, 3,977,860 and 3,853,530. Roundup® Herbicide comprising the IPA salt of glyphosate is sold by Monsanto Company as an aqueous concentrate formulation which is diluted in water prior to application. Researchers have suggested that formulated mixtures of glyphosate and ammonium sulfate are, in many cases, more efficacious than formulated glyphosate alone. ( Weed Research 1975 vol. 15, 13-19; and 1980 vol. 20, 139-146). Unfortunately, such formulations of glyphosate and ammonium sulfate with surfactants will salt out upon standing for relatively short periods of time. The short shelf life of these mixture formulations makes them commercially unacceptable. Therefore, the farmer is generally required to tank mix the glyphosate-ammonium sulfate mixture on site just prior to use. This inconvenience has resulted in farmers avoiding the use of glyphosate-ammonium sulfate mixtures. It is desired in the art to find a shelf-­ stable, aqueous, concentrate formulation containing both glyphosate and ammonium sulfate. Summary of the Invention The present invention relates to a herbicidal aqueous concentrate glyphosate/ammonium sulfate formulation comprising a water-soluble glyphosate salt, ammonium sulfate and a quaternary ammonium salt. Suitable classes of quaternary ammonium salts useful in the present invention include quaternized long chain amines; quaternized polyoxyalkylenated long chain amines; quaternary salts of pyridines; quaternary salts of carboxylated imidazolines (open and closed chain) and trialkyl betaines. Trialkylamine oxides which comprise a class of compounds which form quaternary ammonium hydroxide salts upon addition to water are also useful in the practice of the present invention. Other general classes of quaternary ammonium salts useful in the practice of the present invention will be known to those skilled in the art. Preferred subclasses of quaternary ammonium salts for use in the present invention are alkylloweralkyl, dihydroxyloweralkyl ammonium chlorides; alkyl, trilower­ alkyl ammonium chlorides; carboxymethylated imidazoline and alkyldiloweralkyl betaines. The formulation of the present invention is shelf-stable to enable its commercial distribution as one package mixture. The formulation can be easily used by the farmer and is readily diluted in water prior to its use. The formulation avoids the problems of having to tank mix the glyphosate-ammonium sulfate mixture on site just prior to use. A more thorough disclosure of the present invention is presented in the detailed description which follows. Detailed Description of the Invention The present invention relates to a herbicidal, aqueous concentrate formulation of glyphosate and ammonium sulfate comprising water-soluble glyphosate salt, ammonium sulfate and quaternary ammonium salt. The formulation also contains water. The formulation of the present invention is shelf-stable in that it does not experience salting out of ingredients when stored for prolonged periods of time at lower ambient temperatures (e.g. temperatures as low as 0°C and lower). The shelf-stability of the formulation of the present invention enables its commercial distri­ butions as a one package mixture. The formulation of the present invention contains a water-soluble salt of glyphosate. Several processes for the preparation of glyphosate are disclosed in the patent and chemical literature, e.g., U.S. Patents 3,977,860 and 4,486,358. Suitable water-soluble salts of glyphosate useful in the present invention are disclosed in U.S. Patent 4,405,531. The isopropyl amine salt of glyphosate is preferred in the formulation of the present invention. Commercially available fertilizer grade ammonium sulfate may be used in the formulation of the present invention. Other grades of ammonium sulfate useful in the practice of the present invention will be known to those skilled in art. During the formulation process, the formulations are normally filtered to remove any insoluble particulate materials which may be present in some commercial grades of ammonium sulfate. The key feature of the formulation of the present invention is the quaternary ammonium salt. A variety of quaternary ammonium salts can be utilized in the practice of the present invention. Suitable anions for the quaternary ammonium salts of the present invention include the chloro anion, hydroxy anion and the phosphate anion. Other suitable anions will be known to those skilled in the art. The quaternary ammonium salt functions to stabilize the formulation. Suitable classes, subclasses and species of quaternary ammonium salts for use in the present invention are as follows: 1. quaternized long chain amines: a) alkyl, triloweralkyl ammonium chloride i) trimethyl coco ammonium chloride (coco = C₁₂-C₁₅ alkyl) ii) trimethyl octadecyl ammonium chloride b) dialkyl, diloweralkyl ammonium chloride i) dimethyl, dioctadecyl ammonium chloride 2. quaternized polyoxyalkylenated long chain amines: a) dialkyl dihydroxyethyl ammonium chloride i) methyl bis(2-hydroxyethyl) coco ammonium chloride ii) methyl bis(2-hydroxyethyl) lauryl ammonium chloride iii) methyl bis(2-hydroxyethyl) oleo ammonium chloride b) alkyl di(polyoxyethylene) lower alkyl ammonium chloride i) methyl bis(omegahydroxypoly(oxyethylene)coco) ammonium chloride where the polyoxyethylene is derived from 3-20 moles of ethylene oxide ii) methyl bis(omegahydroxypoly(oxyethylene)oleo) ammonium chloride where the polyoxyethylene is derived from 3-20 moles of ethylene oxide c) hydroxyalkyl polyoxyethylene diloweralkyl ammonium chloride i) hydroxyethyl dimethyl polyoxyethylene (2 moles) ammonium chloride d) alkyl tri(polyoxyethylene) ammonium phosphate i) lauryl tripolyoxyethylene ammonium phosphate 3. quaternized pyridines i) N-octyl pyridine chloride ii) N-dodecyl pyridine chloride 4. quaternized carboxylated imidazolines (closed and open chain). i) N-carboxymethyl N-aminoethyl undecyl imidazoline ii) N-carboxy N-hydroxyethyl undecyl imidazoline iii) N-carboxymethyl N-aminoethyl-(N′,N′-dicarboxy­ methyl) undecyl imidazoline iv) N-carboxymethyl N-(carboxymethoxy) ethyl undecyl imidazoline v) N-carboxymethyl N-hydroxyethyl heptadecyl imidazoline ( stearoamphoglycinate) iv) N-carboxymethyl N-hydroxyethyl undecyl imidazoline ( lauroamphoglycinate) 5. trialkyl betaines a) alkyl, diloweralkyl betaines i) lauryl dimethyl betaine ii) stearyl dimethyl betaine iii) coco dimethyl betaine iv) decyl dimethyl betaine 6. amine oxides a) trialkylamine oxides i) lauryl dimethyl amine oxide ii) stearyl dimethyl amine oxide b) dihydroxyethyl alkyl amine oxide i) dihydroxyethyl octyl amine oxide ii) dihydroxyethyl dodecyl amine oxide iii) dihydroxyethyl tallowamine oxide c) di(polyhydroxyethylene) alkyl amine oxide i) bis(polyoxyethylene) tallowamine oxide d) loweralkyl polyoxyethylene alkyl amine oxide i) methyl polyoxyethylene (2 mole) cocoamine oxide Other general class, subclasses and species of quaternary ammonium salts useful in the practice of the present invention will be known to those skilled in the art. Certain quaternary ammonium salts will provide for more stable formulation than others and those skilled in the art will be able to readily optimize formulations of the present invention by selection of suitable quaternary ammonium salts and by varying the concentration of the formulation ingredients. Quaternary ammonium salts useful in the formulation of the present invention are commercially available from a number of manufacturers and are generally described in McCutcheon's Detergents and Emulsifiers , North American Edition 1985 Annual and in McCutcheon's Detergent and Emulsifiers International Edition 1985. The formulations may optionally contain a secondary surfactant. A suitable class of secondary surfactant are the nonionic surfactants. Suitable nonionic surfactants are polyoxyethylene alkylphenyl­ ether, polyoxyethylene oleyl ether and dialkylene glycol monoalkyl ether. Additional suitable secondary nonionic surfactants are set forth in U.S. Patent 4,405,531. Other suitable nonionic surfactants will be known to those skilled in the art. The water-soluble concentrate formulations of the present invention are comprised as follows: The formulations of the present invention may be generally prepared by mixing the ingredients together in a blender. The formulations of the present invention may also be admixed with other additives such as urea, thickening agents, anti-foam agents such as silicones, water-repellants, humectants, chelating agents, dyes, dispersing agents, and other active ingredients such as herbicides and fungicides or the like. The formulations of the present invention can be readily diluted in water by the farmer in a spray tank prior to use. Suitable application rates of glyphosate will vary depending on plant species, but generally 90 to 360 grams per hectare on an acid equivalent basis will be suitable. The following examples are presented to illustrate the present invention as well as some of the various embodiments of the invention. These examples are presented as being illustrative of the novel formulations and are not intended to be a limitation of the scope thereof. Examples I-VIII show suitable formulation in accordance with the present invention. Example IX demonstrates the efficacy of the formulations of the present invention. Example I 218 g of aqueous solution of IPA salt of glyphosate containing 62.6% by weight of the IPA salt, 270 g of ammonium sulfate powder, 23 g of methyl bis (2-hydroxyethyl) coco ammonium chloride, 3 g of polyoxyethylenealkyl phenyl ether and 486 g of water are mixed in an agitator at room temperature until the surfactant and ammonium sulfate are dissolved and the solution becomes clear. Usually about 10 minutes is sufficient. This mixing process does not require high shearing nor heating. The resulting formulation is clear. This formulation showed acceptable stability in accelerated aging tests. In two one-month accelerated aging tests where the temp­ erature was set at -5°C for one test and 60°C for the other test, the formulation showed acceptable stability in both tests in that the formulation did not show any change in the appearance, the active ingredient content, and the physical properties such as cloud point, dilution property and the like. The composition of the formulation of Example 1 was as follows: Example II 218 g of aqueous solution of IPA salt of glyphosate (62.6% a.i.), 217 g of ammonium sulfate powder, 134 g of lauryl dimethyl amine oxide, and 377 g of water are mixed gently by an agitator for about 10 minutes. This formulation also showed acceptable stability in one month accelerated aging tests according to Example I. The composition of the formulation of Example II was as follows: Example III The composition of this formulation was as follows: This formulation was prepared in accordance with the procedure of Example II and showed acceptable stability in one month accelerated aging tests according to Example I. Example IV The composition of this formulation was as follows: This formulation was prepared in accordance with the procedure of Example II and showed acceptable stability in one month accelerated aging tests according to Example I. Example V The composition of this formulation was as follows: This formulation was prepared in accordance with the procedure of Example II and showed acceptable stability in one month accelerated aging tests according to Example I. Example VI The composition of this formulation was as follows: This formulation was prepared in accordance with the procedure of Example II and showed acceptable stability in one month accelerated aging tests according to Example I. Example VII The following seven formulations were prepared by standard procedures as set forth in Examples I-VI and showed acceptable stability in 1 week accelerated aging tests where the temperature was set at -5°C and 60°C. Each formulation comprised the following: The surfactants for the seven formulations were as follows: a) lauryl dimethyl betaine b) stearyl dimethyl betaine c) N-octyl pyridine chloride d) lauryl, trimethyl ammonium chloride e) N-octadecyl methyl pyridine chloride f) lauryl, methyl dihydroxyethyl ammonium chloride g) N-carboxymethyl N-hydroxyethyl lauryl imidazoline Example VIII The following formulations were prepared by standard procedure and demonstrated acceptable formula­ tion characteristics. Each formulation comprised 2.22 grams of an aqueous solution of IPA salt of glypho­ sate (62.6% a.i.); 1.9 grams of ammonium sulfate; a quaternary ammonium salt (CTFA name*) and water. * Official nomenclature of Cosmetics, Toiletry and Fragrance Association. CLASS - Quaternized Imidazolines 1. Caproamphoglycinate (37% a.i.) 1.12 g Water 4.76 g 2. Capryloamphocarboxypropionate 1.03 g Water (40% a.i.) 4.85. 3. Capryloamphopropionate 1.09 g Water 4.79 g 4. Cocoamphopropionate 0.91 g (potassium salt) (45% a.i.) Water 4.96 g 5. Mixed short chain alkyl 0.41 g amphopropionate Water 5.47 g CLASS - Quaternized Polyethoxyethylenated long chain amines 9. Methyl bis (2-hydroxyethyl) coco ammonium chloride 0.56 g Water 5.32 g 10. Methyl bis (2-hydroxyethyl) oleo ammonium chloride 0.57 g Water 5.31 g Example IX Mixtures of water-soluble salts of glyphosate and ammonium sulfate are well known in the art to be efficacious as a post-emergent herbicide. The following demonstrates the biological efficacy of the formulation of the present invention when applied to established stands of difficult to control weeds. Although this invention has been described with respect to specific embodiments, the details hereof are not to be construed as limitations, for it will be apparent that various equivalents, changes and modifications may be resorted to without departing from the spirit and scope of this invention and it is understood that such equivalent embodiments are intended to be included within the scope of this invention.

Claims: 1. An aqueous concentrate herbicidal formulation comprising water soluble glyphosate salt, ammonium sulfate and quaternary ammonium salt. 2. The formulation of Claim 1 wherein the water-soluble glyphosate salt is the isopropyl amine salt. 3. The formulation of Claim 1 wherein the quaternary ammonium salt is a quaternized polyoxyethylenated long chain amine. 4. The formulation of Claim 3 wherein the quaternary ammonium salt is dialkyl dihydroxyethyl ammonium chloride. 5. The formulation of Claim 4 wherein the quaternary ammonium salt is methyl bis (2-hydroxyethyl)­ coco ammonium chloride. 6. The formulation of Claim 1 wherein the quaternary ammonium salt is a quaternized long chain amine. 7. The formulation of Claim 6 wherein the quaternary ammonium salt is trimethyl coco ammonium chloride. 8. The formulation of Claim 1 wherein the quaternary ammonium salt is a quaternized carboxylated imidazoline. 9. The formulation of Claim 8 wherein the quaternary ammonium salt is N-carboxymethyl N-aminoethyl (N′,N′-dicarboxymethyl) undecyl imidazoline. 10. The formulation of Claim 1 wherein the quaternary ammonium salt is a quaternized pyridine. 11. The formulation of Claim 10 wherein the quaternary ammonium salt is N-octyl pyridine chloride. 12. The formulation of Claim 1 wherein the quaternary ammonium salt is trialkyl betaine. 13. An aqueous concentrate herbicidal formulation comprising a water soluble salt of glyphosate, ammonium sulfate and trialkyl amine oxide. 14. The formulation of Claim 13 wherein the salt of glyphosate is the isopropyl amine salt. 15. The formulation of Claim 14 wherein the trialkyl amine oxide is lauryl dimethyl amine oxide.

Inventors: KUCHIKATA, MASUO, SATO, TATSUO
Applicants: MONSANTO COMPANY
Application year: 1987
Main classification: A01N57
IPC codes: A01N59, A01N25, A01N57