Microencapsulation formulations of cadusafos

• US 6,440,443 B1
• Filed: 07/29/1999
• Issued: 08/27/2002
• Est. Priority Date: 07/30/1998
• Status: Expired due to Term

• Current Assignee: FMC Corporation
• Original Assignee: FMC Corporation
• Inventors: Nicholson, Paul, Szamosi, Janos, Sommer, William T., Lee, Fui-Tseng H.
• Primary Examiner(s): Levy, Neil S.
• Application Number:
  US09/363,342
• Time in Patent Office: 1,125 Days
• Field of Search: 264/4.33, 424/405, 424/408, 424/417, 424/406, 424/490, 424/497, 274/109, 274/120, 274/121
• US Class Current: 424/408
• CPC Class Codes: A01N 2300/00 Combinations or mixtures of active ingredients covered by classes A01N27/00 - A01N65/48 with other active or formulation relevant ingredients, e.g. specific carrier materials or surfactants, covered by classes A01N25/00 - A01N65/48
• CPC Class Codes: A01N 25/28 Microcapsules or nanocapsules
• CPC Class Codes: A01N 57/12 containing acyclic or cycloaliphatic radicals

Abstract

Pesticidal formulations of cadusafos are provided. An aqueous capsule suspension is provided, containing from about 150 to about 360 grams of cadusafos per liter of formulation and having lower mammalian toxicity than aqueous cadusafos microemulsion formulations is prepared by interfacial polymerization of a first polyfunctional compound, such as a polymethylene polyphenyl isocyanate, with a second polyfunctional compound, such as a polyfunctional amine or mixtures of polyfunctional amines, in an aqueous phase optionally containing from about 0.05 to about 0.50 xanthan gum viscosity modifier/stabilizer. A granular form of the microencapsulated cadusafos is also provided. Several such formulations and the method of their preparation are described.

Claims

1. A pestidical formulation prepared according to a process comprising the steps of:

a) providing an aqueous phase containing one or more emulsifiers and an antifoam agent;

b) providing a water-immiscible phase, said water-immiscible phase comprising cadusafos and an isocyanate monomer;

c) emulsifying the water-immiscible phase in the aqueous phase forming a dispersion of water-immiscible droplets in the aqueous phase; and

d) adding to the dispersion an aqueous solution of one or more polyfunctional amines, in an amount effective to achieve interfacial polymerization with the isocyanate monomer, thereby forming microencapsules of cadusafos having reduced mammalian toxicity as compared with known aqueous microemulsion cadusafos formulations of an equivalent or lesser cadusafos concentration.

2. A pesticidal formulation prepared according to a process comprising the steps of:

(a) providing an aqueous phase comprised of the one or more emulsifiers and an antifoam agent, and optionally, a xanthan gum viscosity modifier/stabilizer and, optionally, a bactericide;

b) providing a water-immiscible phase comprised of cadusafos optionally pre-treated with a copper salt, polymethylene polyphenyl isocyanate and, optionally, a hydrocarbon solvent;

c) emulsifying the water-immiscible phase in the aqueous phase, forming a dispersion of water-immiscible droplets throughout the aqueous phase;

d) agitating the dispersion while adding thereto an aqueous solution comprised of one or more polyfunctional amines;

e) curing the microcapsules by continuing the agitation while heating the dispersion; and

f) optionally, neutralizing the pH of the formulation with an acid.

14. The pesticidal formulation of claim 2, wherein

a) the weight percent of the one or more emulsifiers is about 0.3 to about 5.0 weight percent of the aqueous phase; the weight percent of the antifoam agent is about 0.1 to about 1.0 weight percent of the aqueous phase;

the weight percent of the xanthan gum viscosity modifier/stabilizer, if any is used, is about 0.05 to about 0.50 weight percent of the aqueous phase; and

the weight percent of the bactericide, if any is used, is about 0.02 to about 0.1 weight percent of the aqueous phase;

b) the weight percent of cadusafos is about 50 to about 98 weight percent of the water-immiscible phase;

the weight percent of the polymethylene polyphenyl isocyanate cadusafos is about 2 to about 35 weight percent of the water-immiscible phase; and

the weight percent of the hydrocarbon solvent, if any is used, is about 15 to about 30 weight percent of the water-immiscible phase;

c) the weight percent of the one or more polyfunctional amines is about 10 to about 100 weight percent of the aqueous solution; and

d) the dispersion is heated at a temperature in the range of about 20 to about 60°

C. for one to ten hours.

15. The pesticidal formulation of claim 14, wherein the one or more emulsifiers is polyvinyl alcohol and the weight percent of the polyvinyl alcohol is about 0.7 to about 2.5 weight percent of the aqueous phase;

the weight percent of the antifoam agent is about 0.3 to about 0.9 weight percent of the aqueous phase;

the weight percent of cadusafos is about 53 to about 92 weight percent of the water immiscible phase;

the weight percent of the isocyanate is about 4 to about 25 percent of the water-immiscible phase; and

the weight percent of the hydrocarbon solvent, if any is used, is about 20 to about 25 percent of the water immiscible phase.

3. A pesticidal formulation of cadusafos comprising an aqueous suspension of microcapsules, the microcapsules comprising a polyurea shell surrounding a core of the cadusafos, the polyurea shell having been formed from interfacial polymerization of an isocyanate and one or more polyfunctional amines, the polyurea shell being sufficiently impermeable to the cadusafos so as to effect a reduction in mammalian toxicity of the formulation as compared with aqueous microemulsion formulations having an equivalent or lesser cadusafos concentration.

4. The pesticidal formulation of claim 3, wherein said pesticidal formulation comprises the aqueous suspension of microcapules and contains from about 150 to about 360 grams of cadusafos per liter of formulation.

5. The pesticidal formulation of claim 3, comprising about 200 grams of cadusafos per liter of formulation.

6. The pesticidal formulation of claim 3, wherein the isocyanate is polymethylene polyphenyl isocyanate (PMPPI).

7. The pesticidal formulation of claim 3, wherein the polyfunctional amine is selected from the group consisting of diethylenetriamine, triethylenetetramine, 1,6-hexanediamine, and a combination of one or more of diethylenetriamine, triethylenetetramine, and 1,6-hexanediamine.

8. The pesticidal formulation of claim 3, which further comprises optionally, about 0.06 to about 0.4 weight percent of xanthan gum viscosity modifier/stabilizer;

optionally, about 0.03 to about 0.05 of one or more bactericides;

optionally, about 0.7 to about 6.7 weight percent of one or more surfactants; and

optionally, about 1.2 to about 5.8 weight percent of propylene glycol or urea;

said weight percents being based on the weight of the total formulation.

9. A granular pesticidal formulation of cadusafos, comprising carrier particles coated with the microcapsules of claim 3.

10. The granular formulation of claim 9, comprising about 5 to about 30 weight percent microcapsules, about 60 to about 95 weight percent carrier, and about 0.05 to about 5.0 weight percent of an adhesive agent;

said weight percents being based on the weight of the total formulation.

11. A pesticidal formulation of from about 150 to about 360 grams cadusafos per liter of formulation, about 0.7 to about 2.5 weight percent polyvinyl alcohol and about 0.3 to about 0.9 weight percent of an antifoam agent, the formulation comprising an aqueous suspension of microcapsules, the microcapsules comprising a polyurea shell surrounding a core of the cadusafos, the polyurea shell having been formed from interfacial polymerization polymethylene polyphenyl isocyanate and one or more polyfunctional amines, wherein the weight percent of cadusafos is about 53 to about 92 percent of a water-immiscible phase provided for the interfacial polymerization, the weight percent of the polymethylene polyphenyl isocyanate is about 4 to about 25 percent of the water-immiscible phase, the polyfunctional amine is selected from the group consisting of diethylenetriamine, triethylenetetramine, 1,6-hexanediamine, and a combination of one or more of diethylenetriamine, triethylenetetramine, and 1,6-hexanediamine, the weight percent of the polyvinyl alcohol and antifoam agent are based on the total composition of the formulation with water included, and said formulation has reduced mammalian toxicity as compared with known aqueous microemulsion cadusafos formulations of an equivalent or lesser cadusafos concentration.

13. The pesticidal formulation of claim 11, wherein the weight percent of cadusafos is up to 98 weight percent of the water-immiscible phase and-the weight percent of the first polyfunctional amine is about 2 to 35 weight percent of the water-immiscible phase.

12. A pestidical formulation of cadusafos, comprising carrier particles coated with an aqueous pesticidal formulation of from about 150 to about 360 grams cadusafos per liter of aqueous formulation, about 0.7 to about 2.5 weight percent polyvinyl alcohol and about 0.3 to about 0.9 weight percent of an antifoam agent, the aqueous formulation comprising an aqueous suspension of microcapsules, the microcapsules comprising a polyurea shell surrounding a core of the cadusafos, the polyurea shell having been formed from interfacial polymerization of polymethylene polyphenyl isocyanate and one or more polyfunctional amines, wherein the weight percent of cadusafos is about 53 to about 92 percent of a water-immiscible phase provided for the interfacial polymerization, the weight percent of the polymethylene polyphenyl isocyanate is about 4 to about 25 percent of the water-immiscible phase, the polyfunctional amine is selected from the group consisting of diethylenetriamine, triethylenetetramine, 1,6-hexanediamine, and a combination of one or more of diethylenetriamine, triethylenetetramine, and 1,6-hexanediamine, the weight percent of the polyvinyl alcohol and antifoam agent are based on the total composition of the aqueous formulation with water included, and said aqueous formulation has reduced mammalian toxicity as compared with known aqueous microemulsion cadusafos formulations of an equivalent or lesser cadusafos concentration.

16. A granular pesticide formulation of cadusafos prepared according to a process comprising drying the coated carrier particles of claim 12.