PARAQUAT FORMULATION

Abstract

The present invention relates to pesticidal emulsions comprising an aqueous continuous phase comprising paraquat and at least one polyvinylalcohol or polyvinylalcohol derivative; a dispersed oil phase; a pesticidal active ingredient; and at least two polymeric surfactants selected from a sorbitan ester and an ethoxylated sorbitan ester. It also relates to the use of a pesticidal emulsion to control undesired vegetation.

Claims

1. A pesticidal emulsion comprising: (a) an aqueous continuous phase comprising paraquat at a concentration of from 50 to 360 g/l, and at least one polyvinylalcohol or polyvinylalcohol derivative; (b) a dispersed oil phase comprising a heavy aromatic hydrocarbon solvent; (c) at least one pesticidal active ingredient selected from butafenacil and S-metalochlor dissolved in the dispersed oil phase; (d) a polymeric sorbitan ester surfactant; and (e) a polymeric ethoxylated sorbitan ester surfactant; wherein components (d) and (e) are located at the interface between components (a) and (b).

2. The pesticidal emulsion of claim 1, wherein the at least one pesticidal active ingredient is butafenacil.

3. The pesticidal emulsion of claim 2, wherein the weight ratio of paraquat to component (c) is from 400:1 to 100:10.

4. The pesticidal emulsion of claim 1, wherein the dispersed oil phase is present as droplets which have a median diameter of 1 μm or less as measured by light scattering.

5. The pesticidal emulsion of claim 1, wherein the at least one pesticidal active ingredient is S-metalochlor.

6. The pesticidal emulsion of claim 5, wherein the weight ratio of paraquat to component (c) is from 300:500 to 50:150.

7. The pesticidal emulsion of claim 1, wherein the dispersed oil phase is present as droplets which have a median diameter of 2 μm or less as measured by light scattering.

8. The pesticidal emulsion of claim 1, wherein the polymeric ethoxylated sorbitan ester (e) has a mean value of from 4 to 20 ethylene oxide groups.

9. A method of controlling undesired vegetation, comprising: applying the pesticidal emulsion of claim 1 to the undesired vegetation.

Description

FORMULATION EXAMPLE 1: OIL IN WATER EMULSION (EW) CONTAINING PARAQUAT, BUTAFENACIL, POLYVINYLALCOHOL-ACETATE COPOLYMER, SPAN™ 40, TWEEN™ 40, ISOPAR™ M, AND SOLVESSO™ 200

[0060] (i) Preparation of Oil Phase [0061] SOLVESSO™ 200 ND and ISOPAR™ M were added together and stirred gently. DOWANOL™ PnB (a propylene glycol n-butyl ether often used to solvate or couple hydrophobic formulation components), may be added if required, followed by TWEEN™ 40. The resulting mixture was heated to about 40° C., followed by the addition of butafenacil, and the mixture stirred until all the butafenacil dissolved. SPAN™ 40 was added and the resulting mixture stirred until all the SPAN™ 40 has dissolved, to provide the oil phase as a clear to slightly hazy oil with no solid material present.

[0062] (ii) Preparation of Aqueous Phase [0063] A pre-formed Mowiol® 4-88 solution in water was added to a solution of paraquat dichloride with sufficient mixing to ensure that the Mowiol® 4-88 solution dissolved in the paraquat. The dye, pyridine bases and NaOH solution were then added to provide a brown solution with no solid material present.

[0064] (iii) Preparation of the Emulsion [0065] The oil phase was added to the aqueous phase at medium flow rate with high shear mixing. After all the oil phase had been added, the resultant mixture was stirred using the high shear mixer for a further 15 minutes. A fluid dark green emulsion was formed.

[0066] Examples of formulations prepared according to Formulation Example 1 are shown in Table 1 below.

TABLE-US-00001 TABLE 1 Ingredient (grams/litre) A B C D E Paraquat dichloride 757.6 757.6 757.6 757.6 757.6 solution in water (33% w/w paraquat ion) Mowiol ® 4-88 100.0.sup.a 100.0.sup.a 0.0 0.0 0.0 (20% w/w in water) Mowiol ® 4-88 NIL NIL 100.0.sup.b 100.0.sup.b 125.0.sup.c (30% w/w in water) 10% w/w NaOH 2.0 2.0 2.0 2.0 2.0 Sulfacide blue 5J 2.5 2.5 2.5 2.5 2.5 Pyridine bases 1.0 1.0 1.0 1.0 1.0 Butafenacil 5.59 5.59 5.59 5.59 5.59 (99.3%) DOWANOL ™ PnB NIL 23.75 23.75 NIL NIL SPAN ™ 40 2.0 2.0 2.0 2.0 2.0 TWEEN ™ 40 48.0 48.0 48.0 48.0 48.0 ISOPAR ™ M 22.0 22.0 22.0 22.0 22.0 SOLVESSO ™ 200ND To 1 L To 1 L To 1 L To 1 L To 1 L .sup.a20.0 g/l actual Mowiol ®; .sup.b30.0 g/l actual Mowiol ®; .sup.c37.5 g/l actual Mowiol ®

FORMULATION EXAMPLE 2: OIL IN WATER EMULSION (EW) CONTAINING PARAQUAT, BUTAFENACIL, POLYVINYLALCOHOL-ACETATE COPOLYMER, SPAN™ 20, TWEEN™ 22, ISOPAR™ M, AND SOLVESSO™ 200

[0067] (i) Preparation of Oil Phase [0068] SOLVESSO™ 200 ND and ISOPAR™ M were added together and stirred gently. DOWANOL™ PnB is added if required, followed by TWEEN™ 22. The resulting mixture was heated to about 40° C., followed by the addition of butafenacil, and the mixture stirred until all the butafenacil dissolved. SPAN™ 20 was added and the resulting mixture stirred until all the SPAN™ 40 has dissolved, to provide the oil phase as a clear to slightly hazy oil with no solid material present.

[0069] (ii) Preparation of Aqueous Phase [0070] A pre-formed Mowiol® 4-88 solution in water was added to paraquat dichloride solution with sufficient mixing to ensure that the Mowiol® 4-88 solution dissolved in the paraquat. The dye, pyridine bases and NaOH were then added to provide a brown solution with no solid material present.

[0071] (iii) Preparation of the Emulsion [0072] The oil phase was added to the aqueous phase at medium flow rate with high shear mixing. After all the oil phase had been added, the resultant mixture was stirred using the high shear mixer for a further 15 minutes to provide a fluid dark green emulsion.

[0073] Examples of formulations prepared according to Formulation Example 2 are shown in Table 2 below.

TABLE-US-00002 TABLE 2 Ingredient (grams/litre) L M Paraquat dichloride solution in 757.6 757.6 water (typically 33% w/w paraquat ion) Mowiol ® 4-88 125.0 125.0 (30% w/w in water) 10% w/w NaOH 2.0 2.0 Sulfacide blue 5J 2.5 2.5 Pyridine bases 1.0 1.0 Butafenacil (typically 99.3%) 5.59 5.59 SPAN ™ 20 0.88 2.0 TWEEN ™ 22 21.12 48.0 ISOPAR ™ M 22.0 22.0 SOLVESSO ™ 200ND To 1 L To 1 L

[0074] Table 3 shows the formulations where the complete emulsifier package (Mowiol® 4-88/SPAN™ 40/TWEEN™ 40) was not used. In these cases the emulsion concentrates did not form.

TABLE-US-00003 TABLE 3 Ingredient (grams/litre) N P Q R Paraquat dichloride solution in 757.6 757.6 757.6 757.6 water (typically 33% w/w paraquat ion) Mowiol ® 4-88 (30% w/w in 125.0 125.0 NIL 125.0 water) 10% w/w NaOH 2.0 2.0 2.0 2.0 Sulfacide blue 5J 2.5 2.5 2.5 2.5 Pyridine bases 1.0 1.0 1.0 1.0 Butafenacil (typically 99.3%) 5.59 5.59 5.59 5.59 SPAN ™ 40 NIL 2.0 2.0 NIL TWEEN ™ 40 48.0 NIL 48.0 NIL ISOPAR ™ M 22.0 22.0 22.0 22.0 SOLVESSO ™ 200ND To 1 L To 1 L To 1 L To 1 L

[0075] For formulations comprising paraquat and butafenacil, particle size, and physical stability in terms of phase separation were studied over a wide range of temperatures. The results of which are shown in Table 4, below. Crystal growth of butafenacil was also studied as butafenacil crystal growth has been observed in other mixtures of paraquat and butafenacil, due to the recrystallization of butafenacil in aqueous media. The results clearly show that the formulations of this invention do not promote butafenacil crystal growth.

[0076] The viscosity of the formulations of the invention were also assessed. Any formulation that contains more than 10% w/w aromatic hydrocarbon must have a viscosity greater than 20.5 mm.sup.2/sec at 40° C. (OECD 114 Test Method).

TABLE-US-00004 TABLE 4 Stability, Particle Size & Rheology Data After storage Before storage Diameter Butafenacil Initial Viscosity Initial Diameter d(0.9) Crystal Storage at 40° C. d(0.9) microns microns Separation Growth Period (mpas) A 0.29 0.30 trace none 15 months 15.1 B 0.34 1.35 10% none 15 months 12.9 C 0.23 0.24 trace none 9 months 22.7 D 0.25 0.24 trace none 9 months 22.0 E 0.23 0.24 trace none 6 months 26.5 F 0.20 0.22 trace none 2 years 23.4 L 0.50 0.52 trace none 2 months — M 0.35 0.28 trace none 2 months — N 0.22 0.22 Trace none 2 months — P 1.9 Heavy bottom Heavy bottom Heavy bottom 1 month — separation.sup.e separation.sup.e separation.sup.e Q 30.4.sup.d NOT NOT NOT NOT — TESTED TESTED TESTED TESTED R 3.2 Heavy bottom Heavy bottom Heavy bottom 1 month — separation.sup.e separation.sup.e separation.sup.e .sup.ddid not emulsify; .sup.etest discontinued

FORMULATION EXAMPLE 3: OIL IN WATER EMULSION (EW) CONTAINING PARAQUAT, S-METALOCHLOR, POLYVINYLALCOHOL-ACETATE COPOLYMER, SPAN™ 20, TWEEN™ 22, SELVOL™ 523, AND AROMATIC™ 200

[0077] (i) Preparation of Oil Phase [0078] In one container AROMATIC™ 200 ND, TWEEN™ 22, S-metolachlor and SPAN™ 20 were mixed together.

[0079] (ii) Preparation of Aqueous Phase [0080] SELVOL™ 523, cis-3-hexenol, silicone anti-foam (SAG 1572), and dye were added to an aqueous solution of paraquat dichloride with sufficient mixing to ensure that the SELVOL™ 523 solution dissolved in the paraquat.

[0081] (iii) Preparation of the Emulsion [0082] The oil phase was added to the aqueous phase at slow flow rate with high shear mixing. After all the oil phase had been added, the resultant mixture was stirred at high shear for a further 10 minutes to ensure complete mixing of the two phases.

[0083] An example of the formulation prepared according to Formulation Example 3 is shown in Table 5 below.

TABLE-US-00005 TABLE 5 An example of the range of formulations which may be prepared according to the invention: Quantity Ingredient (grams/litre) Paraquat dichloride 140-180 Polyvinyl alcohol/acetate 140-160 Silicon antifoam emulsion 0.55 Brilliant blue (dye) 2.5 Pyrimidine base 0.45 S-metolachlor 200-280 SPAN ™ 20 0.88 TWEEN ™ 22 21 Cis-3-hexenol 1 AROMATIC ™ 200ND 132

[0084] The following Tables 6 to 8 provide further example compositions of the ranges listed above in Table 5.

TABLE-US-00006 TABLE 6 Quantity Ingredient (grams/litre) Paraquat dichloride 140 Polyvinyl alcohol/acetate 140 Silicon antifoam emulsion 0.55 Brilliant blue (dye) 2.5 Pyrimidine base 0.45 S-metolachlor 200 SPAN ™ 20 0.88 TWEEN ™ 22 21 Cis-3-hexenol 1 AROMATIC ™ 200ND 132

TABLE-US-00007 TABLE 7 Quantity Ingredient (grams/litre) Polysorbate 17.95-24.29 Sorbitan ester 0.75-1.01 S-metolachlor 210-270 Solvent - Naphtha (petroleum) 112.50-152.21 Heavy Aromatic Paraquat dichloride 148-180 Water Rest Polyvinyl alcohol 12.99-17.57

TABLE-US-00008 TABLE 8 Quantity Ingredient (grams/litre) Polysorbate 21.12 Sorbitan ester 0.88 S-metolachlor 240 Solvent - Naphtha (petroleum) 132.36 Heavy Aromatic Paraquat dichloride 160 Water Rest Polyvinyl alcohol 15.28

[0085] Example formulations comprising paraquat and S-metolachlor, were tested over a wide range of temperature and time periods for changes in serum, pH, viscosity and particle size. The results of this study are shown in Table 9, below.

TABLE-US-00009 TABLE 9 Stability, Particle Size & Rheology Data Viscosity Particle Size Serum pH (cps) (μm) Dv(95) Initial — 4.54 124 1.18 8 wks @ RT 0 4.53 78 1.32 8 wks @ 50° C. 1.9 4.36 87 1.35 8 wks @ 38° C. 0 4.49 86 1.33 8 wks @ 0° C. 0 4.66 75 1.27 12 wks @ RT 0 4.49 83 1.33 12 wks @ 50° C. 1.8 4.32 91 1.39 12 wks @ 38° C. 0 4.41 81 1.35 12 wks @ 0° C. 0 4.66 75 1.27 24 wks @ RT 1.9 4.50 70 1.34 24 wks @ 50° C. 3.8 4.16 80 1.47 24 wks @ 38° C. 1.9 4.36 70 1.38 24 wks @ 0° C. 0 4.69 70 1.29

[0086] Table 9 shows that significant separation (recorded in Table 9 under the title ‘Serum’) of the formulation was not seen. For some of the samples, especially at higher temperatures, a creaming layer was seen, but this readily mixed back into the formulation.

Glufosinate/Glyphosate Incompatibility with Polyvinylalcohol-Acetate Copolymer (Mowiol® 4-88)

[0087] Table 10 details the maximum ratio of polyvinylalcohol-acetate copolymer (Mowiol® 4-88) to glufosinate and water at which the polyvinylalcohol-acetate copolymer does not precipitate. Above these ratios the polyvinylalcohol-acetate copolymer does precipitate, and glufosinate cannot be formulated as an oil-in-water emulsion (EW) at a commercially acceptable concentration using the Mowiol® 4-88/SPAN™ 40 and TWEEN™ 40 system.

TABLE-US-00010 TABLE 10 Quantity Ingredient % w/w Ammonium glufosinate 8.49 Mowiol ® 4-88 (20% w/w in water) 1.36 Water 90.15

[0088] Table 11 details the maximum ratio of polyvinylalcohol-acetate copolymer (Mowiol® 4-88) to glyphosate and water at which the polyvinylalcohol-acetate copolymer does not precipitate. Above these ratios the polyvinylalcohol-acetate copolymer does precipitate, and glyphosate cannot be formulated as an EW at a commercially acceptable concentration using the Mowiol® 4-88/SPAN™ 40 and TWEEN™ 40 system.

TABLE-US-00011 TABLE 11 Quantity Ingredient % w/w Potassium glyphosate 5.76 Mowiol ® 4-88 (20% w/w in water) 0.76 Water 93.48