WO2005041661A1

WO2005041661A1 - Composition for use as an adjuvant, and method of preparing the composition

Info

Publication number: WO2005041661A1
Application number: PCT/AU2004/000586
Authority: WO
Inventors: David Johnson
Original assignee: Caltex Australia Petroleum Pty Ltd
Priority date: 2003-10-21
Filing date: 2004-05-06
Publication date: 2005-05-12
Also published as: CN1870890A; CN100527956C

Abstract

The invention relates to a composition for use as an adjuvant for a pesticide, the composition comprising: (i) a super wetter; (ii) a petroleum oil; and (iii) a surfactant to effect suspension of the super wetter in the petroleum oil and emulsify the petroleum oil when the composition is added to water; wherein the composition is homogeneous. The invention also relates to a method of preparing such a composition.

Description

COMPOSITION FOR USE AS AN ADJUVANT, AND METHOD OF PREPARING THE COMPOSITION

FIELD OF THE INVENTION The present invention relates to a composition for use as an adjuvant and a method of preparing the composition. The composition has been developed primarily for use as an adjuvant for pesticides.

BACKGROUND OF THE INVENTION Adjuvants are used in combination with pesticide formulations to enhance the efficacy of the active ingredient in the formulation (the Al). Adjuvants achieve this by improving the emulsifying, dispersing, initial spray droplet size and evaporation rate, foliar droplet retention, spreading, wetting, solubilising, evaporating or surface- modifying properties of the pesticide formulation. A desire to improve the efficiency and efficacy of pesticides has led to continued development in adjuvant technology over the decades. Adjuvants may be added to a pesticide formulation during the production of the pesticide formulation, or mixed with the pesticide formulation, e.g. in a spray tank, by the user prior to application of the pesticide formulation to a crop. Common adjuvants include surfactants, compatibility agents, anti-foaming agents, petroleum spray oils and drift control polymers. Surfactants are agents which improve the emulsifying, dispersing, spreading, wetting, or other surface tension related properties of liquids. Surfactants achieve these effects because of their amphiphilic chemical structures. Surfactants are generally utilised in adjuvant compositions to increase the spray coverage of the pesticide formulation on foliage. This assists in the uptake of the pesticide into crops. Surfactants include emulsifying agents, wetting agents (spreaders), and some stickers. Petroleum spray oils (PSOs) have long been used as adjuvants for pesticides. A PSO usually consists of up to about 5% surfactant suspended in an oil of petroleum origin. This small amount of surfactant allows the PSO to be dispersed in water as an emulsion. PSOs can offer benefits in droplet drift control, evaporation, deposition, wetting, spreading, cuticular penetration and rainfastness. The petroleum oil type and the surfactant type and level in the PSO formulation can all affect the efficacy of an Al. A main mode-of-action of PSO adjuvancy arises through the ability of the petroleum oil to improve the permeation of the leaf cuticle by the Al by softening or swelling the cuticular structure. The low volatility of petroleum oils can contribute to another mode-of-action of PSO adjuvancy by maintaining the droplet deposit in a liquid state on the leaf surface for long periods of time following water evaporation from the droplet. PSO formulations have shelf-lives limited by the solubility of the surfactant in the oil. It is usually difficult to formulate PSOs on low concentrations of surfactant when the surfactant's solubility in the oil is limiting. The surfactant selected for a PSO formulation must therefore be of sufficient solubility, or must self-assemble into oil soluble agglomerates, to impart adequate shelf-life to the PSO, as well as being capable of producing an emulsion of satisfactory stability when the PSO is added to water. Crop oil concentrates (COCs) are also known in the adjuvant market. COCs contain about 75 to 90% petroleum or vegetable-derived oil and about 10 to 25% surfactant. The high level of surfactants in COCs allows them to be used at lower rates in the tank mixture than PSOs and in some situations can also promote better Al efficacy than PSOs. An excess level of surfactants is required to maintain the reduction in the droplet leaf interfacial tension as the droplet spreads. If excess surfactant is present then dilution of the effective concentration of surfactant at the advancing front of the droplet can be prevented and surfactant lost by adsorption to the leaf surface can be replenished. Another advantage of some COCs is the ability of the surfactant to solubilise the plant cuticle thereby facilitating the passage of the Al through this barrier. More recently, COCs have been used in place of PSOs as adjuvants in herbicide spray mixtures. A range of surfactants have been used in PSO and COC compositions. Most surfactants used are nonionic but other formulations can be made with ionic surfactants or a mixture of ionic and nonionic surfactants. The hydrophilic aspect of nonionic surfactants is often achieved by the inclusion of ethylene or propylene oxide subunits in the surfactant structure while the hydrophobicity can be achieved from long hydrocarbon chains. The chemistry of the hydrophilic and hydrophobic sections of the surfactant molecule influences not only the mixing of the oil with the water, but also the composition's shelf-life, and the persistence of the formulation on the leaf (leaf persistence), cuticular penetration rate and tank-mix compatibility of the PSO or COC. The type of surfactant used in a PSO or COC formulation is therefore very important and can have a major effect on its overall performance. WO 01/89299 discloses the use of an organosiloxane copolymer containing separate terminal or pendant amino-containing and polyether-containing functional groups, and compositions containing such organosiloxanes, as an adjuvant for herbicides. US 5,504,054 discloses agricultural spray compositions (e.g. pesticidal compositions) comprising a superspreading low-foaming trisiloxane surfactant. The document discloses the addition of a superspreading low-foaming trisiloxane surfactant to agricultural spray mixtures to provide a composition having low foaming properties. It would be advantageous to provide new compositions for use as adjuvants to improve the efficiency and efficacy of pesticides.

SUMMARY OF THE INVENTION In a first aspect, the present invention provides a composition for use as an adjuvant for a pesticide, the composition comprising: (i) a super wetter; (iϊ) a petroleum oil; and (iii) a surfactant to effect suspension of the super wetter in the petroleum oil and emulsify the petroleum oil when the composition is added to water; wherein the composition is homogeneous.

In a second aspect, the present invention provides a composition for use as an adjuvant for a pesticide, the composition comprising: (i) a super wetter; (ii) a petroleum oil; (iii) water; and (iv) a surfactant to, in combination with water, effect suspension of the super wetter in the petroleum oil and emulsify the petroleum oil when the composition is added to water; wherein the composition is in the form of a homogeneous water-in-oil microemulsion. The surfactant used in the composition according to the first or second aspect of the invention may be a nonionic surfactant, or an ionic surfactant, or a mixture of two or more nonionic surfactants, or a mixture of two or more ionic surfactants, or a mixture of one or more nonionic surfactants and one or more ionic surfactants. In a third aspect, the present invention provides a method of preparing a composition according to the first aspect of the present invention, the method comprising mixing a super wetter, a surfactant to effect suspension of the super wetter in the petroleum oil and emulsify the petroleum oil when the composition is added to water, and a petroleum oil in amounts sufficient to form a homogeneous composition. In a fourth aspect, the present invention provides a method of preparing a composition according to the second aspect of the present invention, the method comprising mixing a super wetter, a surfactant to effect suspension of the super wetter in the petroleum oil and emulsify the petroleum oil when the composition is added to water, water and a petroleum oil in amounts sufficient to form a homogeneous water-in-oil microemulsion. In a fifth aspect, the present invention provides a method of suspending a super wetter in a petroleum oil, the method comprising mixing the super wetter, the petroleum oil, and a surfactant to effect suspension of the super wetter in the petroleum oil. In a sixth aspect, the present invention provides a method of suspending a super wetter in a petroleum oil, the method comprising mixing the super wetter, the petroleum oil, a surfactant to effect suspension of the super wetter in the petroleum oil, the surfactant being of sufficient solubility in the oil to prevent phase separation occurring within the resultant mixture, and sufficient water to initiate formation of an inverted microemulsion. The surfactant used in the method according to the third, fourth, fifth or sixth aspect of the invention may be a nonionic surfactant, or an ionic surfactant, or a mixture of two or more nonionic surfactants, or a mixture of two or more ionic surfactants, or a mixture of one or more nonionic surfactants and one or more ionic surfactants. The method according to the fifth or sixth aspect of the present invention may be used to prepare, respectively, a composition according to the first aspect of the present invention or a composition according to the second aspect of the present invention. In a seventh aspect, the present invention provides a method of enhancing the efficacy of a pesticide in controlling pests on a crop, the method comprising applying to the crop a mixture comprising the pesticide and a composition according to the first or second aspect of the present invention. The crop may be a single plant or multiple plants, and the pest may be on or in the vicinity of the plant(s). In an eighth aspect, the present invention provides the use of a composition according to the first or second aspect of the present invention as an adjuvant for a pesticide. In a ninth aspect, the present invention provides the use of a composition according to the first or second aspect of the present invention in the preparation of a pesticide. In a tenth aspect, the present invention provides the use of a composition according to the first or second aspect of the present invention as a pesticide. DEFINITIONS As used in this Specification including the Claims, the term "pesticide" means a substance used to control pests of any sort, and includes insecticides, insect growth regulators, herbicides, fungicides, nematicides, miticides and acaricides. Plant growth regulators, which in certain amounts can act as plant hormones, are included within the scope of the term "pesticide" used in this Specification including the Claims. As used in the Summary of the Invention, the Detailed Description of the Invention, and the Claims, the term "homogeneous" in relation to a microemulsion or composition means a microemulsion or composition which has a uniform dispersion of the components of the microemulsion or composition. As used in the Summary of the Invention, the Detailed Description of the Invention, and the Claims, the term "super wetter" means a hydrophiHcally substituted organosilicone surfactant which is capable of lowering the static surface tension of water to less than or equal to 25 mN/m at its critical micelle concentration (cmc). DETAILED DESCRIPTION OF THE INVENTION The present invention will now be described in further detail. Organosilicone surfactants can modify the surface-active properties of non-polar solvents (such as oils) or water. Generally, the organosilicone backbones can be either hydrophobically substituted with alkyl chains to impart surface activity in non-polar solvents, or hydrophilically substituted, usually with polyoxyethylene or polyoxypropylene groups, copolymers thereof, or anionic, cationic or amphoteric groups, to impart surface activity in water. Hydrophilically substituted organosilicone surfactants modify the surface-active properties of water and can act as rainfasteners. Above the cmc, certain hydrophilically substituted organosilicone surfactants have a water spreading ability superior to most surfactants. Because of this, certain hydrophilically substituted organosilicone surfactants are sometimes referred to as organosilicone "super wetters". Super wetters can promote complete coverage of the agrochemical on the target foliage usually leading to an increase in the efficacy of the Al. Super wetters can be based on methyl-substituted trisiloxanes, trimethyl silanes and organo-polysiloxane copolymer backbones. Polymeric forms can be based on a number of different subunits, the most common of which is the dimethylsiloxane chain. Super wetters are effective spreaders of aqueous agrochemical solutions because they rapidly lower spray droplet surface tension and significantly reduce the interfacial tension between the droplet and the plant surface. Usually, only organosilicone surfactants with molecular weights less than about 1500 have the desired combination of properties of low final surface tension and rapid reduction of the surface tension to this final surface tension. Thus super wetter organosilicone surfactants are distinguished from other organosilicone surfactants by the rate at which individual surfactant molecules tend to move to interfacial surfaces, and the low surface tension they create at the interface. Rapid reduction to a very low final surface tension is advantageous and most beneficial on hard-to-wet, hydrophobic surfaces and leads to spontaneous spreading of droplets, promoting superior spreading and coverage, stomatal flooding and direct contact between Al and leaf surface. The present inventor sought to gain the value of super wetters and the value of

COCs from a single homogeneous composition by incorporating a super wetter into a COC, for use as an adjuvant. It was desirable that the composition have a commercially acceptable shelf-life, i.e. a composition in which the components remained uniformly dispersed for a commercially acceptable period of time, preferably for at least two years. However, during the course of early investigations by the inventor, it was initially found that super wetters could not be effectively solubilised in typical COC formulations. In such compositions, the super wetter separated from the petroleum oil. The present inventor surprisingly found that a homogeneous adjuvant composition comprising a super wetter and a petroleum oil could be prepared by using a surfactant which effected suspension of the super wetter in the oil and caused emulsification of the petroleum oil when the composition was added to water. Suitable surfactants were found to include surfactants having a hydrophobic group which was chemically similar to the petroleum oil matrix and a hydrophilic group which was of sufficient size to favour the formation of inverted micelles. The present inventor also surprisingly found that a homogeneous adjuvant composition comprising a super wetter and a petroleum oil could be prepared by including a surfactant and water in the composition. It was found that a number of surfactants were suitable for use in combination with water to produce a homogeneous water-in-oil microemulsion. It was further found that the addition of a small amount of water could reduce the concentration of surfactant needed to solubilise the super wetter. For example, certain surfactant systems could be utilised at less than equimolar concentrations with the super wetter, by the addition of a small amount of water. It is known to those skilled in the art that surfactants will self-assemble into various types of aggregates, or phases, depending on the relative dimensions of the hydrophilic and hydrophobic groups, surfactant concentration, the nature of the continuous phase, and temperature. When the hydrophobic group is of similar proportions to the hydrophilic group, the surfactant will favour formation of bilayer aggregates. Super wetters are an example of surfactants that favour bilayer aggregates when in sufficient concentration. In petroleum oils, super wetter bilayers are not particularly soluble and they phase separate quickly. Other surfactants form more soluble aggregates in petroleum oil. Such aggregates can take the form of inverted spherical micelles. Linear alcohol ethoxylates are an example of surfactant that can form soluble aggregates in petroleum oil across a wide range of concentrations. It is known to those skilled in the art that an inverted, water-in-oil (w/o) microemulsion can be formed in oil/surfactant/water systems when the interfacial tension between the dispersed water phase and continuous oil phase is reduced to close to zero. W/o microemulsions are of indefinite stability because they are thermodynamically stable. The relative dimensions of the hydrophilic and the hydrophobic sections of a surfactant determine its packing geometry at the water/oil interface, if the hydrophilic head group is small enough relative to the hydrophobic tail, then a microemulsion of inverted w/o micelles can form if sufficient surfactant is present. Cosurfactants can be used to improve the surfactant packing efficiency by effectively increasing the relative volume of the hydrophobic tail. Certain molecules in the petroleum oil matrix can also act as cosurfactants for surfactants of suitable size and shape. Cosolvents can also be used in PSO and COC formulations to alter the polarity of the petroleum oil so that surfactants and other additives can be made more miscible with the petroleum oil. Without wishing to be bound by theory, the present inventor hypothesises that, in the compositions according to the first aspect of the present invention, either the surfactant forms inverted micelles with the super wetter in the oil matrix or the surfactant acts as a cosolvent in the oil matrix, resulting in a homogeneous adjuvant composition having satisfactory commercial shelf-life. In the case of the compositions according to the second aspect of the present invention, it is hypothesised that water initiates the formation of an inverted water-in-oil microemulsion. Since the composition is intended to be used in agricultural applications as an emulsifiable oil, it is important that the surfactant system be selected to also emulsify the petroleum oil in water. Surfactants (or surfactant mixtures) with HLB from about 6 to about 12 can be effective for emulsifying petroleum oils. Long alkyl or monounsaturated carbon chains are petroleum oil-compatible hydrophobes. A convenient way of measuring the relative size of the hydrophobe and hydrophile of nonionic surfactants is to use the hydrophilic/lipophilic balance (HLB) approach. Surfactants, or surfactant mixtures, with high HLB (15-20) are water soluble and have too large a hydrophilic group to form suitable inverted micelles in non-polar media. Surfactants, or surfactant mixtures, with low HLB (1-3) are too oil soluble to be attracted to form inverted micelles or microemulsions with small amounts of water dispersed in non-aqueous media. Ionic surfactants having a surface packing ratio of from about 0.7 to about 1.3 can be effective in suspending the super wetter in the petroleum oil, and emulsifying the petroleum oil when the composition is added to water. The surfactant packing ratio, P, is given by the expression: P = V/a_h .l_t where N is the molecular volume of the surfactant, ah is the area of the polar head group of the surfactant molecule and l_t is the length of the hydrophobic tail of the surfactant. When P > 1, inverted micelles and w/o microemulsions are favoured. The presence of w/o promoting cosurfactants effectively increases N without affecting aj, or l . The present invention advantageously provides an adjuvant, in the form of a homogeneous composition, for use in agriculture that provides the spreading and coverage benefits offered by super wetters, combined with the anti-evaporative and cuticular permeation benefits provided by COCs. Such an adjuvant has not previously been contemplated. Advantageously, such a composition enables a user to measure out desired quantities of the composition without the need to mix or shake the composition prior to measuring. The super wetter used in the composition of the present invention may be any super wetter. The super wetter used in the composition of the present invention may be a mixture of two or more super wetters. Preferably, the super wetter lowers the surface tension of water to less than or equal to 25 mN/m in less than about one second at its cmc. The super wetter may, for example, be selected from the group consisting of: (i) trisiloxane polyoxyethylene surfactants of the general formula: Si((-O-TMSi)₂M(-(CH₂)₃-(E/P)_n) where TMSi stands for (CH₃)₃Si-, M stands for -CH₃, (E P)_n stands for a polyoxyethylene group -(OCH^H^_π-R¹ or polyoxypropylene group

or a polymer consisting of a combination of polyoxyethylene and polyoxypropylene, where n is an integer from 1 to 50, and R¹ is -H, -OH, -OCH₃, -OC(O)CH₃, or a linear or branched alkyl or aryl group with 1 to 20 carbon atoms; (ii) trimethylsilane polyoxyethylene surfactants of the general formula: TMSi(CH₂)_m-O-(E/P)_n where m is an integer from 1 to 50, and E/P, n, R¹ and TMSi have the same nomenclature as above; and (iii) low molecular weight (<1500 a.m.u.) polymeric forms based on a substituted siloxane chain of the general formula: R¹-X-[Si(R²)₂-0]a-Si(R²)₂-X-R¹ where the X groups can be either the same or different and are either -(E/P)_p- or -Si(R²) O- groups, p is an integer from 5 to 30, R² can be either the same or different and is either linear or branched alkyl or aryl group with up to 20 carbon atoms or is (E/P)_p-R¹ group, with the proviso that at least one of the R² groups is an (EZP)p-R¹ group, a equals 0 or an integer from 1 to 20, and (E/P) and R¹ have the same nomenclature as above. Preferably, the super wetter is selected from the super wetters defined in (i) or

(ii) above. In some embodiments, the super wetter is selected from the super wetters defined in (i) or (ii) above, wherein n is an integer from 10 to 20, and m is an integer from 1 to 10. In other embodiments, the super wetter is selected from the super wetters defined in (iii) above, wherein a equals 0 or an integer from 1 to 10, and p is an integer

Suitable super wetters include, for example, ethoxylated heptamethyltrisiloxane, polyethoxylated trisiloxane, and ethoxylated polydimethylsiloxane. The super wetter is typically present in the range of from about 2.0% w/w to about 20% w/w of the composition, and preferably in the range of from about 2% w/w to about 10% w/w of the composition. Typically, the petroleum oil used in the composition of the present invention is an oil of petroleum origin having a median distillation point from about 250°C to about 450°C (ASTM D2887). It will be appreciated by those skilled in the art that "petroleum oil" is also referred to as "mineral oil", and encompasses "mineral oil", "white mineral oil", "white oil", "paraffinic oil", "paraffinic mineral oil", "paraffin oil", "saturated paraffin oil", "petroleum base oil" and "lubricating oil". The petroleum oil is typically present in the composition of the invention in the range of from about 30% w/w to about 90% w/w of the composition, and preferably in the range of from about 50% w/w to about 85% w/w of the composition, e.g. in the range of from about 50% w/w to about 80% w/w of the composition. The petroleum oil may be selected from the group consisting of a group I base oil, a group TI base oil, a group HI base oil, and mixtures thereof. The surfactant used in the composition of the invention may be selected from the group consisting of a nonionic surfactant, an ionic surfactant, a mixture of two or more nonionic surfactants, a mixture of two or more ionic surfactants, and a mixture of one or more nonionic surfactants and one or more ionic surfactants. The surfactant is present in the composition of the invention in an amount effective to suspend the super wetter in the petroleum oil and emulsify the petroleum oil when the composition is added to water. Preferably, the surfactant is present at at least about an equimolar concentration with the super wetter. In the case of nonionic surfactants, the surfactant may be selected such that the hydrophilic head group of the surfactant, or the average head group of a mixture of nonionic surfactants, is from about 30% to about 60% of the mass of the nomomc surfactant (HLB from about 6 to about 12). In the case of ionic surfactants, the surfactant maybe selected such that the surfactant packing ratio, P, is from about 0.7 to about 1.3, preferably from about 0.8 to about 1.2. The surfactant may be selected from the group consisting of fatty alcohol ethoxylates, fatty amine ethoxylates, fatty acids and their ethoxylates, alkyl phenol ethoxylates, sorbitan esters and their ethoxylated derivatives, glycol and glyceryl esters and their ethoxylates, ethoxylated oils and fats, N-alky me ylammonium chlorides, N- alkyl imidazoline chlorides, amine and imidazoline hydrochlorides, alkyl benzene and naphthalene sulphonates, sulphosuccinates, alkyl phosphate esters, sulphated oils and glycerides, alkyl phenol ether sulphates, sulphosuccinate diesters, and mixtures thereof. The surfactant is typically present in the range of from about 5% w/w to about 65% w/w of the composition, preferably in the range of from about 5% w/w to about 50% w/w of the composition, and more preferably in the range of from about 5% w/w to about 30%) w/w of the composition. Water is typically present in the composition according to the second aspect of the present invention in the range of from about 0.25% w/w to about 10% w/w of the composition, preferably in the range of from about 0.25% w/w to about 7.5% w/w of the composition, and more preferably in the range of from about 0.5% w/w to about 5% w/w of the composition. The composition of the present invention may further comprise a cosolvent to improve the solubility of the surfactant in the petroleum oil. The cosolvent may be selected from the group consisting of esterified vegetable oils, vegetable oils, fish oils, aromatic or unsaturated hydrocarbon solvents, fatty alcohols, aldehyde or ketone solvents, and mixtures thereof. An embodiment of the composition according to the first aspect of the present invention is a composition comprising: (i) from about 3% w/w to about 7% w/w of a super wetter; (ii) from about 70% w/w to about 85% w/w of a petroleum oil; and (iii) from about 8% w/w to about 30% w/w of a surfactant selected from the group consisting of sorbitan esters and their ethoxylated derivatives, and mixtures thereof; wherein the composition is homogeneous. An embodiment of the composition according to the second aspect of the present invention is a composition comprising: (i) from about 3% w/w to about 7% w/w of a super wetter; (ii) from about 70% w/w to about 85% w/w of a petroleum oil; (iii) from about 0.5% w/w to about 5% w/w water; and (iv) from about 8% w/w to about 30% w/w of a surfactant selected from the group consisting of sorbitan esters and their ethoxylated derivatives, and mixtures thereof; wherein the composition is in the form of a homogeneous water-in-oil microemulsion. The shelf-life of compositions can be determined using common physical test methods, e.g. CIPAC MT 46.1.3. A composition of the present invention is typically stable for more than six months, typically for more than three years, when stored at room temperature. Accelerated shelf-life testing at 54°C showed that the compositions of the present invention typically remained homogeneous for up to 21 days at this temperature. Advantageously, in preferred embodiments of the composition of the invention, the composition is a stable, homogeneous composition. The composition according to the first aspect of the present invention may be prepared by mixing a super wetter, a surfactant and a petroleum oil in amounts sufficient to form a homogeneous composition. A cosolvent may be added to improve the solubility of the surfactant in the petroleum oil. Typically, the composition according to the first aspect of the present invention is made by mixing the surfactant into a mixture of petroleum oil and super wetter until a homogeneous composition is formed. In an embodiment of the invention, the process of formulating a composition according to the first aspect of the present invention from petroleum oil and a super wetter with nonionic surfactants was undertaken using a matched pair of surfactants. An ethoxylated surfactant of high HLB was selected to emulsify the petroleum oil, while its ability to form an inverted mixed micelle with the super wetter was enhanced by the addition of its non-ethoxylated, low HLB partner to act as cosurfactant. The composition according to the second aspect of the present invention may be prepared by mixing a super wetter, a surfactant, water and a petroleum oil in amounts sufficient to form a homogeneous water-in-oil microemulsion. A cosolvent may be added to improve the solubility of the surfactant in the petroleum oil. Typically, the composition according to the second aspect of the present invention is made by mixing the surfactant into a mixture of petroleum oil and super wetter. Water is then added and the mixture mixed until a homogeneous water-in-oil microemulsion is formed. In an embodiment of the invention, the process of formulating a composition according to the second aspect of the present invention from petroleum oil and a super wetter with nonionic surfactants was undertaken using a matched pair of surfactants and water. An ethoxylated surfactant of high HLB was selected to emulsify the petroleum oil, while its ability to form an inverted microemulsion with the super wetter and water was enhanced by the addition of its non-ethoxylated, low HLB partner to act as cosurfactant. The composition of the invention may be used as an adjuvant for a pesticide to enhance the efficacy of an Al of the pesticide on a crop by improving the rate and consistency of pest kill. For example, the composition of the invention may be added directly to the tank mix containing one or more pesticides before spraying. The composition of the invention may also be mixed with the pesticide and then applied to the crop. The crop may be a single plant or multiple plants, and a pest may be on or in the vicinity of the plant(s) . When the composition of the invention is added to water in a tank mix for practical end-use as an adjuvant, the high solubility of the super wetter in water allows it to separate from the petroleum oil and act almost independently of the remaining surfactant system which acts to form a typical o/w emulsion. The super wetter reduces the surface tension of the water which allows facile formation of very small o/w micelles and therefore a very stable emulsion for spraying. The composition of the present invention may also be used to manufacture or prepare a pesticidal formulation. For example, the pesticide can be formulated directly into the composition of the invention. The composition of the invention may itself be used as a pesticide. Preferred embodiments of the invention will now be described, by way of example only, with reference to the following Examples and Field Trials. EXAMPLES Example 1 Table 1 shows an example of an embodiment of the composition of the invention. The surfactants, ethoxylated oleic acid and linear alcohol ethoxylate, were blended into the base oil until the mixture was homogeneous. The super wetter was then blended into the mixture followed by the water. The resulting mixture was blended until homogeneous.

Table 1: Components of Example 1

Example 2 Table 2 shows an example of an embodiment of the composition of the invention. The surfactant, ethoxylated oleic acid, was blended into the base oil until the mixture was homogeneous. The super wetter was then blended into the mixture followed by the water. The resulting mixture was blended until homogeneous.

Table 2: Components of Example 2

Example 3 Table 3 shows an example of an embodiment of the composition of the invention. The surfactant, linear alcohol ethoxylate, was blended into the base oil until the mixture was homogeneous. The super wetter was then blended into the mixture until the resulting mixture was homogeneous.

Table 3: Components of Example 3

Example 4 Table 4 shows an example of an embodiment of the composition of the invention. The surfactants, linear alcohol ethoxylate and ethoxylated oleyl amine, were blended into the base oil until the mixture was homogeneous. The super wetter was then blended into the mixture until the resulting mixture was homogeneous.

Table 4: Components of Example 4

Example 5 Table 5 shows an example of an embodiment of the composition of the invention. The anionic ethoxylated alcohol phosphate ester and alcohol ethoxylate were blended into the base oil until the mixture was homogeneous. The super wetter and water were then blended into the mixture until the resulting mixture was homogeneous. Table 5: Components of Example 5

Example 6 Table 6 shows an example of an embodiment of the composition of the invention. The sorbitan esters were blended into the base oil until the rnixture was homogeneous. The super wetter was then blended into the mixture until the resulting mixture was homogeneous.

Table 6: Components of Example 6

Example 7 Table 7 shows an example of an embodiment of the composition of the invention. The ethoxylated sorbitan ester was blended into the base oil until homogeneous. The super wetter and water were then blended into the rnixture until homogeneous. Table 7: Components of Example 7

MELD TRIALS The advantages of the composition of Example 1 were illustrated by replicated field trials under commercial conditions of use. Two small plot replicated field trials were conducted to evaluate the composition as an adjuvant to enhance the performance of the selective grass herbicides clethodim (SELECT 240 EC) and a mixture of the herbicides butroxydim and fluazifop-p (FUSION WG).

Field Trial 1 The first trial was conducted on a commercial farm near Long Plains in the Lower North region of South Australia. The major weed species present was annual rye grass (Lolium rigidum) which was at early tillering stage when sprayed and the crop was field peas. The trial was laid out as a randomised complete block experiment with four replicates. The plot size used was 2 metres by 18 metres. A 0.5 metre unsprayed buffer was left between each treated plot. All treatments were applied using a hand held gas operated 2 metre-boom sprayer incorporating four Spraying Systems 800067 flat fan nozzles. At a speed of 1 metre per second and a pressure of 220 kPa, the treatments were applied in a total volume of 73 L/ha. Assessments for weed control were conducted at 7, 14, 29 and 56 days after treatment (DAT). Weed control was assessed as percentage biomass reduction using a 0- 100 score where 0 = no effect, 50 = 50% reduction in weed biomass, and 100 = complete control of weeds. The results are summarised in Table 8. All data have been analysed using analysis of variance and least significant difference (LSD) techniques. Means with small letters adjacent to them in common are not significantly different at the 95 % level of probability. The adjuvant composition was shown to enhance the performance of SELECT 240EC at lOOml/ha and FUSION WG at lOOg/ha. SELECT provided little control of annual ryegrass without the aid of the adjuvant composition while FUSION provided only minor control without the aid of the adjuvant composition.

Table 8: Summary of results for Field Trial 1 - Long Plains, South Australia. Mean Annual Ryegrass Control Rating (0-100 scale)

Field Trial 2 The second trial was conducted on a commercial farm near York in the southern grain belt of Western Australia. The major weed species present was annual rye grass (Lolium rigidum) which was sprayed at 15-23 Zadoks and the crop was lupins (cv: Gungurru). The trial was laid out as a randomised complete block experiment with four replicates. The plot size used was 2 metres by 12 metres. A 0.5 metre unsprayed buffer was left between each treated plot. All treatments were applied using a hand held gas operated 2 metre-boom sprayer incorporating four Spraying Systems 800067 flat fan nozzles. At a speed of 1.3 metre per second and a pressure of 200 kPa, the treatments were applied in a total volume of 65 L/ha. Assessments for weed control were conducted at 5, 12, 27 and 61 days after treatment (DAT). Weed control was assessed as percentage biomass reduction using a 0-100 score where 0 = no effect, 50 = 50% reduction in weed biomass and 100 = complete control of weeds. The results are summarised in Table 9. All data have been analysed using analysis of variance and least significant difference (LSD) techniques. Means with small letters adjacent to them in common are not significantly different at the 95% level of probability. Again the adjuvant composition was shown to significantly enhance the performance of SELECT 240EC at 125 ml/ha and FUSION WG at 140g ha at various stages throughout the trial. Rainfall between 27 and 61 DAT promoted vigorous weed growth which served to increase the activity of the herbicide in this period. Drier than normal weather prior to 27 DAT slowed the herbicide activity and showed the greatest differences.

Table 9: Summary of results for Field Trial 2 - York, Western Australia. Mean Annual Ryegrass Control Rating (0-100 scale)

Although the invention has been described with reference to particular examples and field trials, it will be appreciated by those skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. All such variations and/or modifications are to be considered within the scope of the present invention the nature of which is to be determined from the foregoing description. It will be appreciated by those skilled in the art that the invention may be embodied in many forms. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. A reference herein to a prior art document is not an admission that the document forms part of the common general knowledge in the art in Australia or in any other country.

Claims

The claims defining the invention are as follows:

1. A composition for use as an adjuvant for a pesticide, the composition comprising: (i) a super wetter; (ii) a petroleum oil; and (iii) a surfactant to effect suspension of the super wetter in the petroleum oil and emulsify the petroleum oil when the composition is added to water; wherein the composition is homogeneous.

2. A composition for use as an adjuvant for a pesticide, the composition comprising: (i) a super wetter; (ii) a petroleum oil; (iii) water; and (iv) a surfactant to, in combination with water, effect suspension of the super wetter in the petroleum oil and emulsify the petroleum oil when the composition is added to water; wherein the composition is in the form of a homogeneous water-in-oil microemulsion.

3. A composition according to claim 1 or 2, wherein the super wetter is selected from the group consisting of: (i) trisiloxane polyoxyethylene surfactants of the general formula: Si((-O-TMSi)₂M(-(CH₂)₃-(E/P)_n) where TMSi stands for (CH₃)₃Si-, M stands for -CH₃, (E/P)„ stands for a polyoxyethylene group -(OCH₂CH₂)_n-R¹ or polyoxypropylene group -(OC^Q ÷CH^_n-R¹ or a polymer consisting of a combination of polyoxyethylene and polyoxypropylene, where n is an integer from 1 to 50, and R¹ is -H, -OH, -OCH₃, -OC(O)CH₃, or a linear or branched alkyl or aryl group with 1 to 20 carbon atoms; (ii) trimethylsilane polyoxyethylene surfactants of the general formula: TMSi(CH₂)_m-O-(E/P)_n where m is an integer from 1 to 50, and E/P, n, R¹ and TMSi have the same nomenclature as above; and (iii) low molecular weight (<1500 a.m.u.) polymeric forms based on a substituted siloxane chain of the general formula: R¹-X-[Si(R²)₂-O]_a-Si(R²)₂-X-R¹ where the X groups can be either the same or different and are either -(E/P)_p- or -Si(R²)₂O- groups, p an integer from 5 to 30, R² can be either the same or different and is either linear or branched alkyl or aryl group with up to 20 carbon 1 atoms or is (E/P)p-R group, with the proviso that at least one of the R groups is an (EZP)_p-R¹ group, a equals 0 or an integer from 1 to 20, and (E/P) and R¹ have the same nomenclature as above.

4. A composition according to any one of claims 1 to 3, wherein the super wetter is selected from: (i) trisiloxane polyoxyethylene surfactants of the general formula: Si((-O-TMSi)₂M(-(CH₂)₃-(E/P)„) where TMSi stands for (CH₃)₃Si-, M stands for -CH₃, (E/P)„ stands for a polyoxyethylene group -(OC^CH^_n-R¹ or polyoxypropylene group -(OCH2CH₂CH₂)n-R^{1 or a} polymer consisting of a combination of polyoxyethylene and polyoxypropylene, where n is an integer from 1 to 50, and R¹ is -H, -OH, -OCH₃, -OC(O)CH₃, or a linear or branched alkyl or aryl group with 1 to 20 carbon atoms.

5. A composition according to any one of claims 1 to 3, wherein the super wetter is selected from (ii) trimethylsilane polyoxyethylene surfactants of the general formula: TMSi(CH₂)_m-O-(E/P)_n where m is an integer from 1 to 50, and E/P, n, R¹ and TMSi are as defined in claim 3.

6. A composition according to any one of claims 1 to 5, wherein the super wetter is present in the range of from about 2.0% w/w to about 20% w/w of the composition.

7. A composition according to claim 6, wherein the super wetter is present in the range of from about 2% w/w to about 10% w/w of the composition.

8. A composition according to any one of claims 1 to 7, wherein the petroleum oil is present in the range of from about 30% w/w to about 90% w/w of the composition.

9. A composition according to claim 8, wherein the petroleum oil is present in the range of from about 50% w/w to about 85% w/w of the composition.

10. A composition according to any one of claims 1 to 9, wherein the petroleum oil is selected from the group consisting of a group I base oil, a group II base oil, a group HI base oil, and mixtures thereof.

11. A composition according to any one of claim 1 to 10, wherein the surfactant is selected from the group consisting of a nonionic surfactant, an ionic surfactant, a mixture of two or more nonionic surfactants, a mixture of two or more ionic surfactants, and a mixture of one or more nonionic surfactants and one or more ionic surfactants.

12. A composition according to claim 11, wherein the surfactant is a nonionic surfactant.

13. A composition according to claim 12, wherein the nonionic surfactant is a surfactant having an HLB from about 6 to about 12.

14. A composition according to claim 11 , wherein the surfactant is an ionic surfactant.

15. A composition according to claim 14, wherein the ionic surfactant has a surfactant packing ratio, P, from about 0.7 to about 1.3.

16. A composition according to claim 15, wherein the ionic surfactant has a surfactant packing ratio, P, from about 0.8 to about 1.2.

17. A composition according to any one of claim 1 to 16, wherein the surfactant is selected from the group consisting of fatty alcohol ethoxylates, fatty amine ethoxylates, fatty acids and their ethoxylates, alkyl phenol ethoxylates, sorbitan esters and their ethoxylated derivatives, glycol and glyceryl esters and their ethoxylates, ethoxylated oils and fats, N-alkyltrimethylammonium chlorides, N- alkyl imidazoline chlorides, amine and imidazoline hydrochlorides, alkyl benzene and naphthalene sulphonates, sulphosuccinates, alkyl phosphate esters, sulphated oils and glycerides, alkyl phenol ether sulphates, sulphosuccinate diesters, and mixtures thereof.

18. A composition according to any one of claims 1 to 17, wherein the surfactant is present in the range of from about 5% w/w to about 65% w/w of the composition.

19. A composition according to claim 18, wherein the surfactant is present in the range of from about 5% w/w to about 50% w/w of the composition.

20. A composition according to claim 19, wherein the surfactant is present in the range of from about 5% w/w to about 30% w/w of the composition.

21. A composition according to claim 2 or any one of claims 3 to 20 when dependent on claim 2, wherein water is present in the range of from about 0.25% w/w to about 10% w/w of the composition.

22. A composition according to claim 21 , wherein water is present in the range of from about 0.25% w/w to about 7.5% w/w of the composition.

23. A composition according to claim 22, wherein water is present in the range of from about 0.5% w/w to about 5% w/w of the composition.

24. A composition according to any one of claims 1 to 23, further comprising a cosolvent to improve the solubility of the surfactant in the petroleum oil.

25. A composition according to claim 24, wherein the cosolvent is selected from the group consisting of esterified vegetable oils, vegetable oils, fish oils, aromatic or unsaturated hydrocarbon solvents, fatty alcohols, aldehyde or ketone solvents and mixtures thereof.

26. A method of preparing a composition according to claim 1, the method comprising mixing a super wetter, a surfactant to effect suspension of the super wetter in the petroleum oil and emulsify the petroleum oil when the composition is added to water, and a petroleum oil in amounts sufficient to form a homogeneous composition.

27. A method of preparing a composition according to claim 2, the method comprising mixing a super wetter, a surfactant, water and a petroleum oil in amounts sufficient to form a homogeneous water-in-oil microemulsion.

28. A method of suspending a super wetter in a petroleum oil, the method comprising mixing the super wetter, the petroleum oil, and a surfactant to effect suspension of the super wetter in the petroleum oil.

29. A method of suspending a super wetter in a petroleum oil, the method comprising mixing the super wetter, the petroleum oil, a surfactant to effect suspension of the super wetter in the petroleum oil, the surfactant being of sufficient solubility in the oil to prevent phase separation occurring within the resultant mixture, and sufficient water to initiate formation of an inverted microemulsion.

30. A method according to claim 26 or 28, wherein a composition of claim 1 is formed.

31. A method according to claim 27 or 29, wherein a composition of claim 2 is formed.

32. A method of enhancing the efficacy of a pesticide in controlling pests on a crop, the method comprising applying to the crop a rnixture comprising the pesticide and a composition according to any one of claims 1 to 25 as an adjuvant.

33. The use of a composition according to any one of claims 1 to 25 as an adjuvant for a pesticide.

34. The use of a composition according to any one of claims 1 to 25 in the preparation of a pesticide.

35. The use of a composition according to any one of claims 1 to 25 as a pesticide.

36. A composition for use as an adjuvant for a pesticide, the composition comprising: (i) from about 3% w/w to about 7% w/w of a super wetter; (ii) from about 70% w/w to about 85% w/w of a petroleum oil; and (iii) from about 8% w/w to about 30% w/w of a surfactant selected from the group consisting of sorbitan esters and their ethoxylated derivatives, and mixtures thereof; wherein the composition is homogeneous.

37. A composition for use as an adjuvant for a pesticide, the composition comprising: (i) from about 3% w/w to about 7% w/w of a super wetter; (ii) from about 70% w/w to about 85% w/w of a petroleum oil; (iii) from about 0.5% w/w to about 5% w/w water; and (iv) from about 8% w/w to about 30% w/w of a surfactant selected from the group consisting of sorbitan esters and their ethoxylated derivatives, and mixtures thereof; wherein the composition is in the form of a homogeneous water-in-oil microemulsion.