composition

Abstract

A granular (GR) composition comprising an agrochemical, a non-aromatic non-ionic surfactant having a Hydrophilic–Lipophilic Balance (HLB) value greater or equal to 8, at least one plasticiser and a carrier.

Description

[0001] Composition

[0002] The present invention relates to granular compositions, together with methods of preparing and using the same.

[0003] The pyrethroid insecticides ("pyrethroids") are a well-known class of insecticides and include, for example, permethrin, cypermethrin, zeta-cypermethrin, fenvalerate, esfenvalerate, deltamethrin, cyhalothrin, lambda-cyhalothrin, gamma-cyhalothrin, bifenthrin, fenpropathrin, cyfluthrin, beta-cyfluthrin, tefluthrin, ethofenprox, natural pyrethrin, tetramethrin, s-bioallethrin, fenfluthrin, prallethrin and 5-benzyl-3-furylmethyl-(E)-(1 R,3S)-2,2- dimethyl-3-(2-oxothiolan- 3-ylidene- methyl)cyclopropane carboxylate.

[0004] Most of the pyrethroids are applied as foliar or aerosol spray applications. However, certain pyrethroids have utility as soil-applied insecticides. One such pyrethroid, which is particularly useful as a soil-applied insecticide, is tefluthrin (chemical name: (2, 3, 5, 6- tetrafluoro-4- methylphenyl)methyl-(1 a,3a)-(Z)-(plus or minus)-3-(2-chloro-3,3,3-trifluoro-1 -propenyl)-2,2- dimethylcyclopropanecarboxylate).

[0005] Tefluthrin is particularly useful in the control of beetles, rootworms (e.g. corn rootworm), cutworms (e.g. black cutworm), wireworms and seed corn maggots, and has been commercialised as a granular (GR) composition.

[0006] Typical granule formulations comprise one or more active ingredients that are absorbed onto a granular carrier. The carrier granule is treated with an application solution containing the active ingredient in order to absorb the active ingredient onto the surface and into the body of the granules. This application solution frequently contains a solvent and a surfactant and this mixture subsequently aids in the dissolution and stabilisation of solid or semi-solid active ingredients. These components prevent crystallisation of the active ingredient and aid in application and penetration of the application solution by reducing viscosity. Surfactants, such as nonylphenol ethoxylates (NPEs), assist in the movement of active ingredients through the soil after application and such surfactants are known to solubilise and stabilise granular compositions.

[0007] Nonyl phenol ethoxylate surfactants have been in use in the agrochemical industry for more than 40 years. However, it has recently come to light that they are highly toxic to aquatic life and the cessation of the use of NPEs in agrochemical formulations has become an important goal. There is therefore a need to develop stable, efficacious agrochemical formulation products with low environmental toxicity that do not contain nonylphenol ethoxylates. Overcoming the challenges created by the removal of the nonylphenol ethoxylates is technically complex as the replacement formulations must still be efficacious and chemically stable as well as able to solubilise and stabilise the pesticide within the granule.

[0008] It has surprisingly been found that above technical problems are solved by the present invention.

[0009] There is therefore provided an a granular (GR) composition comprising: an agrochemical, a non-aromatic surfactant having a Hydrophilic-Lipophilic Balance (HLB) value greater or equal to 8, at least one plasticiser, and a carrier.

[0010] Granules (GR) are hard, solid, dry particles comprised of porous materials and active ingredient. They are used most often for soil treatment. Granules will not cling to plant foliage and so may be directly applied over plants or soil. In an embodiment, the GR formulation is in the form of flowable granules, and may be applied as such.

[0011] Preferably, the agrochemical is present in an amount of from 0.01 to 50 %, from 0.02 to 45 %, preferably from 0.03 to 40 %, more preferably from 0.04 to 35 %, even more preferably from 0.05 to 25%, most preferably from 0.1 to 10%, by weight of the composition.

[0012] The terms ‘agrochemical’ and ‘active ingredient’ will be used interchangeably herein.

[0013] The agrochemical is advantageously a pyrethroid.

[0014] Preferably, tefluthrin is the sole agrochemical.

[0015] Preferably, the tefluthrin is present in an amount of from 0.01 to 10 %, from 0.02 to 8 %, preferably from 0.03 to 7.5 %, more preferably from 0.04 to 5 %, even more preferably from 0.05 to 3 %, most preferably from 0.1 to 2 %, by weight of the composition.

[0016] The term "surfactant" as used herein means any agrochemically acceptable surfactant or surfactant system that enables release of the active ingredient from the granular support. Non-aromatic surfactants are surfactants which do not contain organic moieties which are cyclically conjugated. Aromatic chemistries are typified as comprising, but not limited to, phenyl rings and their derivatives. All references herein to ‘surfactant’ as part of the invention are to be considered as non-aromatic surfactants unless otherwise stated.

[0017] The present surfactant system may comprise one or more surfactants.

[0018] Surfactants can be defined by their HLB values. Hydrophilic-lipophilic balance (HLB) is the balance of the size and strength of the hydrophilic and lipophilic moieties of a surfactant molecule. The Griffin HLB scale ranges from 0 to 20. The determination of HLB value is well documented, for example by Griffin, William C. (1949), "Classification of Surface-Active Agents by 'HLB'" (PDF), Journal of the Society of Cosmetic Chemists, 1 (5): 311-26.

[0019] It is a surprisingly feature of the present invention that a satisfactory technical performance is achieved with a non-aromatic surfactant having a Griffin HLB value greater than or equal to 8. Preferably, the HLB value is from 9 to 16, more preferably from 10 to 15.

[0020] The non-aromatic surfactant is a non-ionic surfactant.

[0021] Preferably, the surfactant is present in an amount of from 0.1 to 10% by weight of the composition, more preferably from 1 to 7.5% by weight of the composition, even more preferably from 2 to 6%, by weight of the composition.

[0022] Examples of non-aromatic surfactants include, but are not limited to, sorbitan and sorbitol esters (including span type esters), sorbitan and sorbitol alkoxylate esters (including tween type alkoxylate esters), esters of mono-, di- and tri-saccharides including sucrose fatty acid esters, alkyl polyglycosides, alkoxylate ethers, alkoxylate esters, esters of alcohols (such as polyglycerol fatty acid esters), and alkoxylates (including co-polymers and block co-polymers).

[0023] Advantageously, the non-aromatic surfactant is a polyoxyalkylene alkyl ether. Preferably the surfactant has an alkyl chain of length C1 to C30, more preferably from 06 to 020.

[0024] Preferably the surfactant is a 04 to 026 ethoxylated propoxylated alcohol, more preferably, the surfactant is a 08-18, ethoxylated propoxylated alcohol. Preferably, the agrochemical composition of this invention contains no, or substantially no, nonylphenol ethoxylate. By ‘substantially no’ we mean that the composition contains less than 0.1 % by weight of the specified compound.

[0025] The term ’plasticiser’ refers to substances which promote plasticity and flexibility of the composition in which they are present. Examples of plasticisers include, but not limited to, esters such as adipates, azelates, citrates, benzoates, ortho-phthalates, terephthalates, sebacates, and trimellitates.

[0026] It has surprisingly been found that the addition of plasticisers improves the stability and / or efficacy of the resulting formulations. Further the present of a plasticiser reduces the viscosity of the preparatory compositions enabling a uniform application of the active ingredient and surfactant to the carrier during formation of the granules.

[0027] Preferably the plasticiser has a solubility in water of less than 100 g / L, from 0 to 90 g / L, preferably from 0 to 75 g / L, more preferably from 0 to 60 g / L, even more preferably from 0 to 50 g / L, most preferably from 0 to 30 g / L.

[0028] Preferably, the plasticiser comprises bis(2-methylpropyl) hexanedioate (diisobutyl adipate).

[0029] Preferably, the plasticiser comprises epoxidized soybean oil.

[0030] More preferably, the plasticiser comprises epoxidized soybean oil and bis(2-methylpropyl) hexanedioate (diisobutyl adipate).

[0031] Preferably the plasticiser is present from 0.01 to 5 %, more preferably from 0.01 to 2%, or even more preferably from 0.1 to 1 %, by weight of the composition.

[0032] The weight ratio of the surfactant to plasticiser is important for certain particularly preferred granular compositions according to this invention. Thus, in these particularly preferred granular compositions, it is preferred that the weight ratio of the surfactant to active ingredient stabilizer is in the range from 50:1 to 1 :1 , preferably from 25:1 to 1 :1 , even more preferably from 20:1 , even more preferably from 15:1 to 1 :1 and most preferably from 10:1 to 1 :1.

[0033] Typically, granule formulations comprise a carrier. A carrier refers to the solid substance that is used to adsorb the active ingredient(s) of the pesticide. It helps to deliver the active ingredient(s) effectively and evenly onto the target area. The carrier may also contain other additives such as surfactants, stabilizers, or adjuvants to enhance the performance and efficacy of the pesticide. Carriers can be organic or inorganic in nature.

[0034] Inorganic carriers are typically comprised of pumice or clays which include, inter alia, attapulgite, montmorillonite, kaolin, bentonite type clays, zeolites, diatomaceous earth, calcium carbonate or silica stone.

[0035] Preferably, the carrier is inorganic material comprises pumice. Preferably the pumice has a granule size of less than 5000 microns or more preferably less than 2000 microns.

[0036] Preferably, the inorganic material comprises extruded granules composed of mixtures of inorganic powdered materials.

[0037] The carrier is present in an amount of from 50 to 99 %, from 60 to 99 %, preferably from 75 to 99%, more preferably from 80 to 99 % or most preferably from 90 to 99%, by weight of the composition.

[0038] The compositions may further comprise a preservative. A preservative is a substance or a chemical that is added to products to prevent decomposition, for example by microbial growth or by undesirable chemical changes.

[0039] Preservatives include, but are not limited to, anti-microbials and antioxidants. Antioxidants prevent or inhibit the oxidation process, suppressing the formation of hydroperoxides, whereas anti-microbials prevent degradation by bacteria. Chemical preservatives are added to compositions, such as agrochemical formulations, in order to increase the stability of the active ingredient.

[0040] Examples of preservatives include, but are not limited to, sorbic acid, ascorbic acid, sodium ascorbate, ascorbyl palmitate, butylated hydroxytoluene, butylated hydroxyanisole, gallic acid, sodium gallate, sulfur dioxide, sulfites and tocopherols.

[0041] Preferably, the preservative comprises an antioxidant.

[0042] Preferably, the antioxidant comprises butylated hydroxytoluene. Preferably, the preservative is present from 0.001 to 1%, more preferably from 0.005 to 0.5%, even more preferably from 0.01 to 0.25%, by weight of the composition.

[0043] The composition advantageously does not contain any hydrophobic components or waterspreading elements, such as oils.

[0044] A second aspect of the present invention provides for a method of controlling insects, comprising applying a composition as described herein to the locus of said insects, in particular to the soil for the growth of plants susceptible to attack by insects.

[0045] The compositions described above can be used in a method for controlling pests, which comprises applying a composition comprising a mixture as described above to the pests or their environment, with the exception of a method for treatment of the human or animal body by surgery or therapy and diagnostic methods practised on the human or animal body. In an embodiment, the use is a non-therapeutic use. In an embodiment, the method is a non- therapeutic method.

[0046] The composition according to the invention is effective against harmful insects, such as the yellow striped flea beetle, that feed on the leaves of brassicas and related plants.

[0047] Soil-applied pesticides (e.g., insecticides, such as tefluthrin) when applied as granular compositions are typically applied at the time of planting, via banded, T-banded, or in-furrow application methods to the soil at the base of the target crop (e.g., corn).

[0048] Application of the granular compositions is typically performed via a metered applicator tube or a granular dispensing unit which places the granular composition between the furrow openers and press wheels but may also use tines, closing wheels or another suitable method so as to incorporate the granular composition within the top three centimeters (~ an "inch") of the soil by the aforementioned methods.

[0049] Accurate metering of the formulation delivers the specified application rate and may be performed electronically or mechanically.

[0050] Suitable application equipment includes systems such as the AMVAC SmartBox system. Other suitable application systems include those made by Allis Chalmers, International Harvester, Noble, White, Gandy, Kinze or John Deere. Alternatively, smaller plots can be treated with hand-held granule applicators such as the Sunper Start (Yamato Nohji Ltd.) or the granule sprayer Saratto (Minoru Industrial Co., Ltd.).

[0051] In a third aspect of the invention, there is provided a method of preparing a composition as described herein.

[0052] Advantageously, if the composition is in the form of a GR, the method of preparation comprises:

[0053] 1. Melting of the active ingredient;

[0054] 2. Solubilising the active ingredient in surfactant and plasticiser;

[0055] 3. Charging a drum mixer with the carrier and the liquid mixture resulting from step 2; and

[0056] 4. Sieving the resulting granules.

[0057] Unless otherwise stated, the weights and concentrations are expressed herein in percentage by weight.

[0058] The invention is described by the following non-limiting Examples.

[0059] EXAMPLES

[0060] Tefluthrin granule formulations were prepared in combination with a range of the co-formulants listed in Table 1.

[0061] Table 1

[0062] Preparation of the granular compositions

[0063] The granular compositions according to the invention were prepared by the following procedure. The carrier was added to the drum mixer. The tefluthrin, surfactant and active ingredient stabiliser were mixed together at 60 °C in a separate container before being added to the carrier by drip wise addition into the drum mixer. The resulting composition was passed through a 2.4 mm (7 mesh) sieve to produce a granule composition of the invention.

[0064] Example 1

[0065] The aim of the experiment was to investigate the effect of Griffin HLB value on the bio-efficacy of the composition. Eight granule formulations were prepared. Formulation 1-1 contains N PE while Formulations 1-2 to 1-7 are according to the invention. The compositions are shown in Table 2.

[0066] In each granule composition, the non-aromatic surfactants were selected from those with Griffin HLB values in the range from 8.1 to 14.0, while Formulation 1-8 did not contain a surfactant.

[0067] Table 2

[0068] The solubilisation and emulsification properties of tefluthrin, surfactants and plasticizer mixtures, were observed alongside that of the plasticizer. The solutions were rated on a scale of 3 (very good) to 0 (very poor). The results of the ratings can be seen in Table 3.

[0069] Table 3

[0070] The data shows that increasing the HLB value of the surfactant also increases the solubilisation and emulsification property rating of the tefluthrin in solution. The data also shows that a combination of surfactant and plasticizer, is equally effective providing that the surfactant is present at a higher ratio to the plasticizer. Biological test method

[0071] The compositions according to this invention were tested for bio-efficacy using the following biological test method. Efficacy was determined in relation to the mortality rates of yellow striped flea beetles.

[0072] A mixture of test product (0.32g) and a culture medium (1 L), were mixed until homogeneous. Approximately 100 mL of the prepared mixture and 50 mL of water were added to a clear cup. Ten adult beetles were placed in a transparent acrylic cylinder closed at each end with a nylon mesh. These were then placed on a filter paper on the surface of the culture medium. The cup was then sealed. Cups were placed in an incubator at 25 °C, 60% relative humidity and Light-Dark cycle of 16\8 hours. The number of dead insects were then counted after 10, 20, 30, 60, 120, 180 minutes, 24 and 72 hours.

[0073] Table 4 shows the mortality rate results from the application of the compositions to populations of the yellow striped beetle.

[0074] Table 4 It was surprisingly found that the composition was as effective, with high mortality rates, with the addition of a plasticiser to the non-aromatic surfactant. There was an increase in efficacy of the composition with increasing Griffin HLB value of the surfactant used.

[0075] Example 2

[0076] The effect of changing the ratio of non-aromatic surfactant to plasticiser was investigated. Nine granule compositions were prepared with the components indicated in Table 5. Formulations 2-2 to 2-9 were prepared according to the invention.

[0077] In each composition the ratio of non-aromatic surfactant to plasticiser was adjusted in the range from 2:8 to 8:2. Two non-aromatic surfactants were investigated with Griffin HLB values of 11.5 and 14.0.

[0078] The compositions were tested for bio-efficacy using the biological test method described above in relation to the mortality rates of yellow striped flea beetle.

[0079] Table 5

[0080] Table 6 sets out the mortality rates from the application of the formulations on the yellow striped beetle.

[0081] Table 6

[0082] The results show that the mortality rate increases proportionally with increasing amount of polyalkylene oxide alkyl ether surfactant in the mixture. The data also show that the higher HLB value the higher the rate of mortality.

[0083] Example 3

[0084] The effect of a preservative into the granule composition was investigated. Two granule compositions were prepared and are detailed in Table 7.

[0085] Formulation 3-1, according to the present invention, was prepared with the preservative, butylated hydroxytoluene, and Formulation 3-2 was prepared without a preservative. The two formulations were subjected to stability storage regimes of 2 weeks at 60 °C, 2 weeks at 54 °C and 4 weeks at 40 °C. The amount of tefluthrin was determined relative to the amount present at the start of the experiment.

[0086] Table 7

[0087] The sample prepared with the preservative butylated hydroxytoluene was found to be stable through the duration of the experiment.

[0088] The invention is defined by the claims.

Claims

Claims1. A granular (GR) composition comprising;(i) an agrochemical;(ii) a non-aromatic, non-ionic surfactant having a Hydrophilic-Lipophilic Balance (HLB) value greater or equal to 8;(iii) at least one plasticiser; and(iv) a carrier.

2. A composition according to claim 1, wherein the agrochemical is tefluthrin.

3. A composition according to claim 1 or 2, wherein the active ingredient is present in an amount from 0.01 to 50 % by weight.

4. A composition according to any of the preceding claims, wherein the non-aromatic surfactant is a polyoxyalkylene alkyl ether.

5. A composition according to any of the preceding claims, wherein the non-aromatic surfactant is a C8-18, ethoxylated propoxylated alcohol.

6. A composition according to any of the preceding claims, wherein the composition comprises no, or substantially no, nonylphenol ethoxylate (NPE).

7. A composition according to any of the preceding claims, wherein the surfactant is present in an amount from 0.01 to 10 % by weight of the composition.

8. A composition according to any of the preceding claims, wherein the plasticiser comprises bis(2-methylpropyl) hexanedioate (diisobutyl adipate), epoxidized soybean oil, or a mixture thereof.

9. A composition according to any of the preceding claims, wherein the plasticiser is present from 0.01 % to 10 % by weight of the composition.

10. A composition according to any of the preceding claims, wherein the ratio of the surfactant : plasticiser is from 50:1 to 1:1.

11. A composition according to any of the preceding claims, wherein the carrier is an inorganic material, preferably pumice.

12. A composition according to any of the preceding claims, wherein the carrier is present in an amount of from 50 to 99 % by weight.

13. A composition according to the preceding claims further comprising a preservative, preferably wherein the preservative is butylated hydroxytoluene.

14. A method for the preparation of formulation as defined in any of claims 1 to 13, comprising the addition of the liquid agrochemical solution to the carrier, preferably to a drum mixer.

15. Use of a composition as defined in claims 1 to 13 for the treatment of pests, preferably the treatment of yellow striped flea beetle.

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