WO2011034444A1

WO2011034444A1 - Herbicidal surfactant formulations

Info

Publication number: WO2011034444A1
Application number: PCT/NZ2010/000182
Authority: WO
Inventors: Raymond Nigel Simms; Kin-Wai Mok
Original assignee: Polygon (Nz) Limited
Priority date: 2009-09-17
Filing date: 2010-09-13
Publication date: 2011-03-24
Also published as: AU2010296099A1; AU2010296099B2

Abstract

The invention relates to a surfactant system for use in a herbicidal formulation or for use as an adjuvant to a herbicidal formulation, particularly a glyphosate herbicidal formulation. The surfactant system comprises at least one surfactant selected from the group comprising alkylpolyglycosides as the principal or main surfactant, and at least one surfactant selected from the group comprising alkylbetaines and alkyl(amidoalkyl)betaines as the secondary or minor surfactant. The invention further relates to a herbicidal formulation, particularly a highly concentrated aqueous herbicidal formulation comprising one or more water soluble salts of N-phosphonomethylglycine and the surfactant system, wherein the total content of the surfactant system in the herbicidal formulation is less than 90 g/L, expressed in active content of surfactants. The invention further relates to a method of controlling unwanted vegetation by application of the herbicidal formulation to the vegetation.

Description

HERBICIDAL SURFACTANT FORMULATIONS

FIELD OF THE INVENTION This invention relates to surfactant systems and in particular to surfactant systems for use in herbicidal formulations, or for use as adjuvants to herbicidal formulations. It has particular, though not sole application to surfactant systems for use in or as adjuvants to glyphosate herbicide formulations.

BACKGROUND OF THE INVENTION Surfactants are commonly used in herbicidal formulations to enhance the activity of the herbicide, by encouraging wetting of the plant by the active herbicidal ingredient or by encouraging penetration of the active herbicidal ingredient into the plant. Surfactants may either be "built-in" to herbicidal formulations or may be added to the herbicidal formulation as adjuvants before use. For example, if the herbicidal formulation is a concentrated formulation, a surfactant or surfactant system could be added separately into the tank mix during dilution of the herbicide concentrate prior to its application.

N-phosphonomethylglycine (common name "glyphosate") is a well known herbicide which is used to control a wide variety of unwanted vegetation in a range of commercial applications, including agriculture, forestry, industrial, municipal, residential, and amenity applications. Glyphosate is relatively insoluble in water so it is generally used in the form of its salts. There are many salts of glyphosate, including sodium salt, potassium salt, ammonium salt, sulphonium salts such as trimethylsulphonium, amine salts such as monoisopropylamine, dimethylamine, and diamines (for example ethylenediamine), and alkanolamines (for example monoethanolamine). Glyphosate formulations containing the monoisopropylamine salt (often referred to as "IPA" salt) are the most widely used glyphosate formulations and are usually sold in concentrated aqueous solutions which usually contain one or more surfactants. Generally in commercial practice it is desired to enhance the activity of glyphosate by the use of one or more surfactants. Some of the surfactants which are commonly used in herbicidal formulations are hazardous, and can be serious irritants to eyes, skin and the respiratory tract, and highly toxic to plants and animals especially aquatic plants and animals, even at low concentrations. They may also contain contaminants which are carcinogenic to humans. In addition, they may not be biodegradable. An example of such a commonly used surfactant is ethoxylated alkyl amine.

Other problems associated with surfactants can be an undesirable generation of foam during dilution, mixing and spraying of the herbicidal formulation by the user.

There are also other formulation problems, in particular it is becoming more and more desirable to increase the active herbicide concentration in formulations so that a given dose of herbicide can be provided in a smaller liquid volume resulting in advantages in terms of transport, storage, handling and container disposal. In terms of glyphosate formulations, concentrations of at least 510 g/L are desired.

It is very difficult to provide such high strength formulations with "built-in" surfactants since the formulations are required to remain chemically and physically stable over extended storage periods and in possible extremes of temperature. Highly concentrated herbicide formulations have a tendency to crystallise and exhibit phase separation when stored for prolonged periods at low temperatures. Traditional surfactants and surfactant blends which attempt to accommodate high concentration glyphosate formulations are problematic in that the high concentration of surfactant required causes immiscibility between the surfactant and the glyphosate. This immiscibility is mainly due to the low water content of the formulation. Hence it can be difficult for traditional surfactants and surfactant blends to adequately support high concentration herbicide formulations.

As mentioned above, generally a high loading of surfactants in herbicidal formulations such as glyphosate formulations is required in order to achieve the desired herbicidal efficacy, and to enable effective utilisation of the formulations. However, the higher the loading of surfactants in the formulation, the less desirable the formulation is, due to the above mentioned disadvantages.

Therefore there is a need for an improved surfactant system for use in herbicidal formulations and/or for use as an adjuvant to herbicidal formulations. Further, there is a need for a stable highly concentrated herbicidal formulation, which has a low loading of surfactants, yet still exhibits a high degree of herbicidal efficacy.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide an improved surfactant system for use in a herbicidal formulation, or one which will at least provide the public with a useful choice. It is a further object of the present invention to provide an improved surfactant system for use as an adjuvant to a herbicidal formulation, or one which will at least provide the public with a useful choice. It is a further object of the invention to provide an improved herbicidal formulation containing said surfactant system, or one which will at least provide the public with a useful choice. It is still a further object of the invention to provide an improved method of controlling unwanted vegetation, or one which will at least provide the public with a useful choice.

SUMMARY OF THE INVENTION

In a first aspect the invention broadly consists in a surfactant system for use in a herbicidal formulation or for use as an adjuvant to a herbicidal formulation, the surfactant system comprising at least one surfactant selected from the group comprising alkylpolyglycosides and at least one surfactant selected from the group comprising alkylbetaines and alkyl(amidoalkyl)betaines.

It has surprisingly been found that this particular combination of surfactants has synergistic activity.

Preferably the alkylpolyglycoside surfactant has the following structural formula:

wherein n is an integer of from about 8 - 16, preferably about 8 - 12, and x (the degree of polymerization) is from 1 - 3, with an average value preferably between about 1.2 - 1.9. Preferably the alkylbetaine or alkyl(amidoalkyl)betaine surfactant has one or more of the following structural formulae:

(I)

R¹R²R²N+-CH₂COO-

(II)

R R³HN+-CH₂-CH₂COO- (III)

R²

/

R -CON-(CH₂)₃N⁺-CH₂COO- \

r² in which formulae:

R¹ represents a linear or branched alkyl group containing 3 to 30 carbon atoms, preferably 3 to 20 carbon atoms, such as propyl, dodecyl, hexadecyl, tetradecyl, octyl, or mixtures thereof, or an alkamide group, such as a dodecanamide;

R which may or may not be identical, represents an alkyl radical, preferably a methyl radical; and

R³ represents a hydrogen atom or an alkyl radical. Preferably the alkylbetaine surfactant is lauryl betaine.

Preferably the alkyl(amidoalkyl)betaine surfactant is cocoamidopropyl betaine.

Preferably the alkylpolyglycoside surfactant is the principal or main surfactant in the surfactant system, and the alkylbetaine or alkyl(amidoalkyl)betaine surfactant is the secondary or minor surfactant in the surfactant system.

Preferably the ratio of alkylpolyglycoside surfactant to alkylbetaine or alkyl(amidoalkyl)betaine surfactant is from about 3 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 40 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active content of the surfactant.

More preferably the ratio of alkylpolyglycoside surfactant to alkylbetaine or alkyl(amidoalkyl)betaine surfactant is from about 5 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 9 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active content of the surfactant.

Preferably the total amount of active surfactant in the surfactant system is from about 30 - 100% w/w. More preferably, the total amount of active surfactant in the surfactant system is from about 50 - 70% w/w.

Preferably, the amount of alkylpolyglycoside surfactant present in the surfactant system is in the range of 35 - 70% w/w as active surfactant.

Preferably, the amount of alkylbetaine or alkyl(amidoalkyl)betaine surfactant present in the surfactant system is in the range of 1 - 20% w/w as active surfactant. The surfactant system may further include dyes, antifoaming agents and other auxiliary additives as may be desired by end-users.

If the surfactant system is to be incorporated into a herbicidal formulation during preparation or manufacture of the herbicidal formulation, preferably a herbicidally enhancing amount of the surfactant system is added to the formulation. Preferably the herbicidally enhancing amount is less than 90 g/L, and preferably is between about 1 - 89 g/L expressed as active content of surfactants. More preferably the herbicidally enhancing amount is less than 80 g/L, and preferably is between about 1 - 79 g/L. Even more preferably the herbicidally enhancing amount is less than 60 g/L. Most preferably the herbicidally enhancing amount is between about 20 - 59 g/L expressed as active content of surfactants. If the surfactant system is to be used as an adjuvant to a herbicidal formulation, preferably a herbicidally enhancing amount of the surfactant system is added to the herbicidal formulation prior to or during mixing and/or dilution of the herbicidal formulation. Preferably, less than two grams active content of the surfactant system is added to one litre of the dilute working solution of the herbicidal formulation, and more preferably less than 0.4 grams active content of the surfactant system is added to one litre of the dilute working solution of the herbicidal formulation.

In a second aspect the invention broadly consists in a surfactant system for use in a herbicidal formulation or for use as an adjuvant to a herbicidal formulation, the surfactant system comprising at least one surfactant selected from the group comprising alkylpolyglycosides and at least one surfactant selected from the group comprising alkylbetaines and alkyl(amidoalkyl)betaines, wherein the ratio of alkylpolyglycoside surfactant to alkylbetaine or alkyl(amidoalkyl)betaine surfactant is from about 3 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 40 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active surfactants.

In a further aspect the invention broadly consists in a herbicidal formulation comprising at least one active herbicidal ingredient and a surfactant system comprising at least one surfactant selected from the group comprising alkylpolyglycosides and at least one surfactant selected from the group comprising alkylbetaines and alkyl(amidoalkyl)betaines.

Preferably the ratio of the surfactants in the surfactant system of the herbicidal formulation is from about 3 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 40 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active surfactants.

More preferably the ratio is from about 5 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 9 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active surfactants.

Preferably the active herbicidal ingredient is present in a concentration of between 10 - 900 g L.

Preferably the active herbicidal ingredient is selected from the group comprising aminophosphate or aminophosphonate herbicides. More preferably the active herbicidal ingredient is N-phosphonomethylglycine, in the form of one or more of its water soluble salts.

Preferably the water soluble salt or salts are selected from the group comprising sodium salt, potassium salt, ammonium salt, amine salts, alkanolamine salts and combinations thereof. Preferably the amine salt or salts are selected from the group comprising isopropylamine salt and other alkylamine salts.

Preferably the alkanolamine salt or salts are selected from the group comprising monoethanolamine salt, diethanolamine salt and triethanolamine salt.

Preferably the herbicidal formulation is in the form of an aqueous liquid concentrate, which is designed to be diluted in a suitable volume of water by the end-user before application.

Where the active herbicidal ingredient is one or more water soluble salts of N- phosphonomethylglycine, preferably the active herbicidal ingredient is present in a concentration of more than 510 g/L, expressed in acid herbicide equivalents. More preferably, the active herbicidal ingredient is present in a concentration of at least 540 g/L. Most preferably, the active herbicidal ingredient is present in a concentration of greater than 550 g/L.

Preferably the alkylpolyglycoside surfactant is present in an amount of between about 1 - 89 ' g/L, expressed in active content of the surfactant. More preferably the alkylpolyglycoside surfactant is present in an amount of between about 20 to 45 g/L. Preferably the alkylbetaine or alkyl(amidoalkyl)betaine surfactant is present in an amount of between about 0.1 - 20 g/L, expressed in active content of the surfactant. More preferably, the alkylbetaine or alkyl(amidoalkyl)betaine surfactant is present in an amount of between about 1 to 15 g/L.

Preferably the total content of the surfactant system in the herbicidal formulation is less than 90 g/L, and preferably is between about 1 - 89 g/L, expressed in active content of surfactants. More preferably the total content of the surfactant system in the herbicidal formulation is less than 80 g/L, and preferably is between about 1 - 79 g/L. Even more preferably the total content of the surfactant system in the herbicidal formulation is less than 60 g/L. Most preferably the total content of the surfactant system in the herbicidal formulation is between about 20 - 59 g/L, expressed in active content of surfactants.

In a further aspect the invention broadly consists in a herbicidal formulation comprising at least one active herbicidal ingredient, and a surfactant system comprising at least one surfactant selected from the group comprising alkylpolyglycosides, and at least one surfactant selected from the group comprising alkylbetaines and alkyl(amidoalkyl)betaines, wherein the total amount of active surfactants in the formulation is less than 90 g/L.

Preferably the total amount of active surfactants in the formulation is less than 80 g/L.

Preferably the total amount of active surfactants in the formulation is less than 60 g/L. In a further aspect the invention broadly consists in a herbicidal formulation comprising at least one active herbicidal ingredient, and a surfactant system comprising at least one surfactant selected from the group comprising alkylpolyglycosides, and at least one surfactant selected from the group comprising alkylbetaines and alkyl(amidoalkyl)betaines, wherein the ratio of the surfactants in the surfactant system of the herbicidal formulation is from about 3 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 40 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active surfactants, and wherein the total amount of active surfactants in the formulation is less than 90 g/L. Preferably the ratio of the surfactants in the surfactant system is from about 5 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 9 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active surfactants. Preferably the total amount of active surfactants in the formulation is less than 80 g/L.

Preferably the total amount of active surfactants in the formulation is less than 60 g/L.

In a further aspect the invention broadly consists in a concentrated aqueous herbicidal formulation comprising one or more water soluble salts of N-phosphonomethylglycine, and a surfactant system comprising at least one surfactant selected from the group comprising alkylpolyglycosides, and at least one surfactant selected from the group comprising alkylbetaines and alkyl(amidoalkyl)betaines.

Preferably the concentration of N-phosphonomethylglycine in the formulation is greater than 510 g/L, expressed in acid equivalency. More preferably the concentration of N- phosphonomethylglycine is at least 540 g/L, expressed in acid equivalency. Most preferably, the concentration of N-phosphonomethylglycine is greater than 550 g/L, expressed in_. acid equivalency.

Preferably the water soluble salt or salts are selected from the group comprising sodium salt, potassium salt, ammonium salt, amine salts, alkanolamine salts and combinations thereof.

Preferably the amine salt or salts are selected from the group comprising isopropylamine salt and other alkylamine salts.

Preferably the alkanolamine salt or salts are selected from the group comprising monoethanolamine salt, diethanolamine salt and triethanolamine salt. Preferably the ratio of the surfactants in the surfactant system of the herbicidal formulation is from about 3 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 40 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active surfactants. More preferably the ratio of the surfactants in the surfactant system of the herbicidal formulation is from about 5 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 9 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active surfactants. Preferably the alkylpolyglycoside surfactant is present in an amount of between about 1 - 89 g/L, expressed in active content of the surfactant. More preferably the alkylpolyglycoside surfactant is present in an amount of between about 20 - 45 g L. Preferably the alkylbetaine or alkyl(amidoalkyl)betaine surfactant is present in an amount of between about 0.1 - 20 g/L, expressed in active content of the surfactant. More preferably, the alkylbetaine or alkyl(amidoalkyl)betaine surfactant is present in an amount of between about 1 - 15 g/L. Preferably the total content of the surfactant system in the herbicidal formulation is less than 90 g/L, and preferably is between about 1 - 89 g/L, expressed in active content of surfactants. More preferably the total content of the surfactant system in the herbicidal formulation is less than 80 g/L, and preferably is between about 1 - 79 g/L. Even more preferably the total content of the surfactant system in the herbicidal formulation is less than 60 g/L. Most preferably the total content of the surfactant system in the herbicidal formulation is between about 20 - 59 g/L, expressed in active content of surfactants.

In a further aspect the invention broadly consists in a concentrated aqueous herbicidal formulation comprising one or more water soluble salts of N-phosphonomethylglycine, and a surfactant system comprising at least one surfactant selected from the group comprising alkylpolyglycosides, and at least one surfactant selected from the group comprising alkylbetaines and ^*alkyl(amidoalkyl)betaines, wherein the N-phosphonomethylglycine is present in an amount of at least 540 g/L, and the total active content of the surfactant system in the formulation is less than 90 g/L.

Preferably the N-phosphonomethylglycine is present in an amount of greater than 550 g/L. Preferably the total amount of active surfactants in the formulation is less than 80 g/L.

In a further aspect the invention broadly consists in a concentrated aqueous herbicidal formulation comprising at least 540 g/L of one or more water soluble salts of N- phosphonomethylglycine, and a surfactant system comprising at least one surfactant selected from the group comprising alkylpolyglycosides, said alkylpolyglycoside surfactant being present in an amount of between about 1 - 89 g/L expressed as active surfactant, and at least one surfactant selected from the group comprising alkylbetaines and alkyl(amidoalkyl)betaines, said alkylbetaine or alkyl(amidoalkyl)betaine being present in an amount of between about 0.1 - 20 g/L expressed as active surfactant, wherein the total amount of active surfactants in the formulation is less than 90 g/L.

Preferably the N-phosphonomethylglycine is present in an amount of greater than 550 g/L.

Preferably the total amount of active surfactants in the formulation is less than 80 g L. Preferably the total amount of active surfactants in the formulation is less than 60 g/L.

In a further aspect the invention broadly consists in a method of controlling unwanted vegetation comprising applying to the vegetation an effective amount of the herbicidal formulation of the present invention.

If the herbicidal formulation is a concentrated formulation, preferably the herbicidal formulation is diluted in a suitable volume of water by the end-user before application.

Preferably the herbicidal formulation is diluted between 50 and 250-fold to form a working solution for application to the unwanted vegetation.

Preferably the herbicidal formulation is applied in an amount of up to 20 L/ha.

In still a further aspect the invention broadly consists in a method of controlling unwanted vegetation comprising obtaining or preparing a surfactant system of the present invention, adding a herbicidally enhancing amount of the surfactant system to a herbicidal formulation comprising at least one active herbicidal ingredient, and applying an effective amount of the herbicidal formulation to the unwanted vegetation.

If the surfactant system is to be incorporated into a herbicidal formulation during preparation or manufacture of the herbicidal formulation, preferably a herbicidally enhancing amount of the surfactant system is added to the formulation. Preferably the herbicidally enhancing amount is less than 90 g/L, and preferably is between about 1 - 89 g/L, expressed as active content of surfactants. More preferably the herbicidally enhancing amount is less than 80 g/L, and preferably is between about 1—79 g/L. Even more preferably the herbicidally enhancing amount is less than 60 g/L. Most preferably the herbicidally enhancing amount is between about 20 - 59 g/L, expressed as active content of surfactants.

If the surfactant system is to be used as an adjuvant to a herbicidal formulation, preferably a herbicidally enhancing amount of the surfactant system is added to the herbicidal formulation prior to or during mixing and/or dilution of the herbicidal formulation. Preferably, less than two grams active content of the surfactant system is added to one litre of the dilute working solution of the herbicidal formulation, and more preferably less than 0.4 grams active content of the surfactant system is added to one litre of the dilute working solution of the herbicidal formulation. The term "herbicidal formulation" as used herein includes formulations comprising one or more herbicides, one or more fungicides, one or more plant growth regulators, or any combination thereof.

The term "herbicidally enhancing amount" as used herein means a sufficient amount of the surfactant system to enhance or improve the biological efficacy of the herbicidal active ingredient of the herbicidal formulation, in comparison to other herbicidal formulations applied without surfactants.

It is acknowledged that the term 'comprise' may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term 'comprise' shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term 'comprised' or 'comprising' is used in relation to one or more steps in a method or process.

DETAILED DESCRIPTION

The following description will describe the invention in relation to preferred embodiments of the invention. The invention is in no way limited to these preferred embodiments as they are purely to exemplify the invention only and it is to be understood that possible variations and modifications that would be readily apparent are intended to be included without departing from the spirit and scope of the invention.

In a first aspect the present invention provides a surfactant system for use in a herbicidal formulation or for use as an adjuvant to a herbicidal formulation. The surfactant system is designed to enhance the herbicidal activity of the active ingredient in the herbicidal formulation. The surfactant system contains at least one surfactant selected from the group comprising alkylpolyglycosides and at least one surfactant selected from the group comprising alkylbetaines and alkyl(amidoalkyl)betaines. It has surprisingly been found that this particular combination of surfactants works synergistically. Suitable alkylpolyglycoside surfactants for use in the present invention can be depicted by the following structural formula:

wherein n is an integer of from about 8 - 16, preferably about 8 - 12, and x (the degree of polymerization) is from 1 - 3, with an average value preferably between about 1.2— 1.9.

These types of surfactants are commercially available. An example of a suitable alkylpolyglycoside product is sold under the trade name AGNIQUE PG 8107-G (from Cognis). This is a liquid composition which contains 68 - 72% of a C_8-10 alkylpolyglycoside with a degree of polymerization of 1.7. Other examples of similar products suitable for use in the invention include ALKADET 15 (from Huntsman), and GLUCOPON 225 DK (from Cognis).

Preferably, the alkylpolyglycoside surfactant has at least about 70% alkylpolyglycoside so as to minimize transportation costs, and the surfactant loading in the herbicidal formulation.

Suitable alkylbetaine and alkyl(amidoalkyl)betaine surfactants for use in the present invention can be depicted by one or more of the following structural formulae: (I)

R¹R²R²N⁺-CH₂COO-

(Π)

R R³HN+-CH₂-CH₂COO- (III)

R²

/

R -CON-(CH₂)₃N^*-CH₂COO- \

R² in which formulae:

R² which may or may not be identical, represents an alkyl radical, preferably a methyl radical; and

R represents a hydrogen atom or an alkyl radical.

These types of surfactants are commercially available. An example of a suitable alkylbetaine product useable in the invention is lauryl betaine sold under the trade name SYNTHECOL BT (from Chemcolour Limited). This is a liquid composition containing 30 - 32% lauryl betaine. An example of a suitable alkyl(amidoalkyl)betaine product useable in the invention is cocoamidopropyl betaine sold under the trade name SYNTHECOL CAB (from Chemcolour Limited). This is a liquid composition containing a minimum of 30% cocoamidopropyl betaine. Preferably, the betaine surfactant has at least about 30% alkylbetaine or alkyl(amidoalkyl)betaine so as to minimize transportation costs, and the surfactant loading in the herbicidal formulation.

The surfactant system of the invention is a blended combination of at least one surfactant selected from each of these classes of surfactants. The surfactants act in synergy so the combination of surfactants has a synergistic effect. In preferred embodiments, the alkylpolyglycoside surfactant is the principal or main surfactant in the surfactant system, and the alkylbetaine or alkyl(amidoalkyl)betaine surfactant is the secondary or minor surfactant in. the surfactant system. In preferred embodiments the ratio of alkylpolyglycoside surfactant to alkylbetaine or alkyl(amidoalkyl)betaine surfactant is from about 3 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 40 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant. More preferably the ratio of alkylpolyglycoside surfactant to alkylbetaine or alkyl(amidoalkyl)betaine surfactant is from about 5 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 9 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant. This ratio is expressed in active content of surfactant.

The surfactant system of the invention can be prepared by slowly adding the alkylbetaine or alkyl(amidoalkyl)betaine surfactant to the alkylpolyglycoside surfactant and mixing at low shear until a homogenous blend is produced. In preferred embodiments of the invention, the total amount of active surfactant in the surfactant system is from about 30 - 100% w/w. More preferably, the total amount of active surfactant in the surfactant system is from about 50 - 70% w/w. The amount of alkylpolyglycoside surfactant present in the surfactant system is preferably in the range of about 35 - 70% w/w, and the amount of alkylbetaine or alkyl(amidoalkyl)betaine surfactant present in the surfactant system is preferably in the range of about 1 - 20% w/w. The remainder of the surfactant system is made up of by-products, including sodium chloride (a by-product of the betaine surfactant), and water (produced during the manufacturing process).

The surfactant system may further include dyes (for example, FDC Brilliant Blue), antifoaming agents (for example, Dow 1410 Antifoam) and other auxiliary additives as may be desired by end-users.

The surfactant system of the invention is intended for use with herbicidal formulations in order to enhance the herbicidal efficacy of the formulation, either by incorporating the surfactant system into a herbicidal formulation during preparation or manufacture of the herbicidal formulation, or by using the surfactant system as a separate adjuvant in conjunction with a herbicidal formulation. For example, the surfactant system can be added to the herbicidal formulation (for example by adding it to the spray tank or other application apparatus) prior to or during use of the formulation.

The surfactant system could be incorporated into or used as an adjuvant to any type of herbicidal formulation, for example, a solid or granular formulation, or a liquid formulation, including a liquid concentrate. These herbicidal formulations may already contain one or more built-in surfactants or wetting agents, or alternatively they may not contain any surfactants or wetting agents at all and therefore will rely on the addition of the surfactant system to increase the efficacy of the herbicidal formulation. If the surfactant system is to be incorporated into a herbicidal formulation during preparation or manufacture of the herbicidal formulation, the different surfactants in the surfactant system can be provided in the formulation as separate ingredients, or they can be provided as a pre-prepared mixture or blend. The surfactant system should be added in an amount sufficient to enhance the herbicidal activity of the active ingredient of the herbicidal formulation. This should be able to be achieved with a low loading of the surfactant system of the invention. Preferably the surfactant system should be added in an amount of less than 90 g/L, expressed as active content of surfactants. More preferably the surfactant system should be added in an amount of less than 80 g/L. Even more preferably the surfactant system should be added in an amount of less than 60 g/L. If the surfactant system is to be used as an adjuvant to a herbicidal formulation, only a small amount of the surfactant system should be required to achieve the desired enhancement of herbicidal activity. For example, the surfactant system could be added to the herbicidal formulation in an amount of from about 0.1 - 2 grams active surfactant per litre of the ready- to-use herbicidal formulation. In a second aspect the present invention provides a herbicidal formulation comprising at least one active herbicidal ingredient, together with the surfactant system as described herein.

The active herbicidal ingredient can be any type of herbicide, fungicide or plant growth regulator. Some examples of herbicides useable in the present invention include glyphosate, glufosinate, diquat, 2,4-D, atrazine, MCPA, metsulfuron, and picloram. The active herbicidal ingredient can be present in an amount from about 10 - 900 g/L. In a preferred embodiment of the invention the active herbicidal ingredient is selected from the group comprising aminophosphate and aminophosphonate herbicides, for example, N-phosphonomethylglycine, whose common name is glyphosate. Because glyphosate is an organic acid of limited water solubility, it is preferably used in the form of one or more of its water soluble salts. Suitable salts include the salts of alkali metals such as sodium or potassium; or ammonium salt; or amine salts including secondary Or primary amines such as isopropylamine, dimethylamine, diamines such as ethylenediamine; or alkanolamine salts such as monethanolamine; or sulphonium salts such as trimethylsulphonium; the salts being present alone or in combination. Although it is envisaged that any herbicidal salt of glyphosate is useable in the formulations of the present invention, preferred glyphosate salts include sodium salt, potassium salt, ammonium salt, isopropylamine salt and other alkylamine salts, monoethanolamine salt, diethanolamine salt, triethanolamine salt and other alkanolamine salts.

Preferably the herbicidal formulation is a concentrated formulation in which the glyphosate concentration is greater than 510 g/L, expressed in acid equivalency. More preferably, the glyphosate concentration is at least 540 g/L, expressed in acid equivalency. Most preferably, the glyphosate concentration is greater than 550 g/L, expressed in acid equivalency. It should be noted that all concentrations of glyphosate referred to herein, unless otherwise stated, are expressed in terms of acid equivalency. Preferably the ratio of the surfactants in the surfactant system of the herbicidal formulation is from about 3 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 40 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active surfactants. More preferably the ratio of the surfactants in the surfactant system of the herbicidal formulation is from about 5 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 9 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active surfactants. Preferably the alkylpolyglycoside surfactant is present in the formulation in an amount of between about 1 - 89 g/L, expressed in active content of the surfactant. More preferably the alkylpolyglycoside surfactant is present in an amount of between about 20 - 45 g/L .

Preferably the alkylbetaine or alkyl(amidoalkyl)betaine surfactant is present in the formulation in an amount of between about 0.1 - 20 g/L, expressed in active content of the surfactant. More preferably, the alkylbetaine or alkyl(amidoalkyl)betaine surfactant is present in an amount of between about 1 - 15 g/L.

Preferably the total content of the surfactant system in the herbicidal formulation is less than 90 g/L, and preferably is between about 1 - 89 g/L, expressed in active content of surfactants. More preferably the total content of the surfactant system in the herbicidal formulation is less than 80 g/L, and preferably is between about 1 - 79 g/L. Even more preferably the total content of the surfactant system in the herbicidal formulation is less than 60 g/L. Most preferably the total content of the surfactant system in the herbicidal formulation is between about 20 - 59 g/L expressed in active content of surfactants. The herbicidal formulations of the present invention are preferably liquid formulations, including soluble concentrates, oil-in-water emulsions, suspension concentrates and suspoemulsions.

Preferably the herbicidal formulation is in the form of a liquid concentrate which is designed to be diluted (usually in a suitable volume of water) prior to application, to a desired strength dependent on the particular application. In preferred embodiments of the invention the herbicidal formulation is a concentrated aqueous formulation, in which at least one water- soluble herbicidal active ingredient is present in concentrated solution in an aqueous phase of the formulation. In this case the formulation may either have a single phase that is an aqueous solution of the herbicidal active ingredient(s), or a continuous phase that is an aqueous solution of the herbicidal active ingredient(s) and one or more non-aqueous discontinuous phases. For example, if it is desired to make a herbicidal formulation comprising or including a herbicidal active ingredient that has limited or low water solubility, the herbicidal active ingredient could be present in a discontinuous non-aqueous phase of the formulation, for example, in an oil phase of an oil-in-water emulsion or in a solid particulate phase of a suspension concentrate. An antifoaming agent may be added to the formulations of the invention. Numerous antifoaming agents are known in the art and commercially available antifoaming agents operate at very low concentrations and hence do not have a major impact on the loading of the formulations. An example of a suitable antifoaming agent is DOW Antifoam 1410. The formulations of the present invention can also comprise other additives and/or excipients such as viscosity modifying agents, dyes, humectants, activity enhancers, anti-freeze agents, crystallization inhibitors, anti-drift agents, wetting agents, thickening agents, compatibilizing agents, additional surfactants, or other additional herbicides or other agrochemicals. However, it is generally preferred not to add too many additives or excipients to the formulations in order to keep the loading of the formulations to a minimum. If other additives or excipients are included, the amount of each should be very low, for example less than about 1% by weight of the formulation, or even less than about 0.1% by weight of the formulation.

The herbicidal formulations of the invention can be prepared by mixing their different constituents, preferably in a jacketed mixing vessel. Preferably the components of the surfactant system or the surfactant system as a pre-prepared mixture or blend is added slowly to the mixture after the other constituents have been mixed. For example, the first step in the preparation of a glyphosate formulation is to react the glyphosate acid in an aqueous medium with a suitable base to form an aqueous solution of the selected salt of glyphosate. For example, if the potassium salt is used, potassium hydroxide can be used, or if the isopropylamine salt is used, monoisopropylamine can be used. Approximately equimolar amounts of glyphosate and the base are used. Once the aqueous solution is prepared with the desired glyphosate acid equivalent concentration, a suitable herbicidally enhancing amount of the components of the surfactant system, or the surfactant system as a pre-prepared mixture or blend, can be added.

The glyphosate formulations of the present invention are active against a broad range of weed species, and can be applied directly to unwanted plants by known means such as boom or aerial spraying, handgun application, knapsack application, application with wiper equipment or application with a mist blower. Thus according to a further aspect of the invention there is provided a method of controlling unwanted vegetation which comprises applying to the vegetation an effective amount of the herbicidal formulation of the invention. If the herbicidal formulation is a concentrated or high-strength formulation it should be diluted with water before application. The amount of dilution required will vary depending on the concentration of the formulation and the intended method of application. The "effective amount" or rate of application of the formulations of the invention will vary depending on a number of factors including, for example, the concentration of the active herbicidal ingredient in the formulation, the method of application, and the identity of the unwanted vegetation and whether the formulation is to be applied for foliage or root uptake. As a general guide, glyphosate formulations of the invention, when applied by boom or aerial spraying, can be applied at a rate of up to about 20 litres per hectare, depending on the weed species to be treated.

Some non-limiting examples of the invention will now be described.

Example 1 The following surfactant systems of the present invention were prepared:

Surfactant Alkylpolyglycoside Total (4)

Alkylpolyglycoside ³' Alkylbetaine Alkyl(amidoalkyl)betaine'⁵' Composition to Betaine Ratio'¹' Surfactant

(approx 70% (approx 31% (approx 31% activity) as Active '²'

activity) activity)

(% w/w) (g) (% w/w) (g) (% w/w) (g) (% w/w)

A 9:1 62 4 56 1 6.2 0 0

B 7 :1 60 6 52.5 2 7.75 0 0

C 5:1 58 11 48.1 5 9.7 0 0

D 9:1 62 4 56 0 0 1 6.2

E 7:1 60 3 52.5 0 0 1 7.75

F 5:1 58 11 48.1 0 0 5 9.7

G 3:1 53 13.5 40.2 10 13.2 0 0

H 15:1 65 6.7 60.9 0 0 1 4.0

I 25:1 67 11 64.2 1 2.6 0 0 J 35:1 68 15.5 65.8 0 0 1 1.9

K 40:1 68 17.7 66.3 1 1.7 0 0

(1) Calculated based on amount by weight of surfactant x % activity of surfactant

(2) Calculated based on (sum of (amount by weight x % activity of each surfactant)) / (total amount by weight of surfactants) x 100 (rounded to nearest whole number)

(3) AGNIQUE PG 8107-G (from Cognis), contains 68-72% C8-10 alkyl polyglycoside, D.P.=1.7

(4) SYNTHECOL BT (from Chemcolour Ltd), contains 30-32% lauryl betaine

(₅) SYNTHECOL CAB (from Chemcolour Ltd), contains 30% minimum cocoamidopropyl betaine

Commercial size batches of the surfactant systems can be prepared by loading the alkylpolyglycoside surfactant into a mixing vessel, then whilst mixing at low shear adding the alkylbetaine or alkyl(amidoalkyl)betaine surfactant, and continuing mixing until a homogenous blend is produced.

The other components of the surfactant systems exemplified above include sodium chloride which is a by-product of the betaine surfactant and water which is a by-product of the manufacturing process. For example, the surfactant system of Formulation B above contains the following components:

Component Function % w/w

Surfactant/

Alkylpolyglycoside 52.5

Wetting Agent

Surfactant/

Alkylbetaine 7.75

Wetting Agent

By-product in

Sodium Chloride 1.75

betaine

Diluent (by¬

Water 38.0

product)

Example 2

A herbicidal formulation of the present invention was prepared with the following composition:

The formulation was prepared by adding water to a jacketed mixing vessel and cooling the water by circulating cold water via a chiller unit. The potassium hydroxide was carefully added to the water and paddle mixed until dissolved. The glyphosate acid was then slowly added to the mixing vessel whilst mixing, and mixing was continued until a clear solution was obtained. The temperature was kept below 65°C during this process. The mix was then cooled to less than 30°C. The surfactant system was then slowly added whilst mixing. The antifoam was then added and mixing was continued for about 30 minutes until a homogenous solution was obtained.

The resulting formulation is a glyphosate herbicide formulation containing the potassium salt. It is envisaged that the glyphosate acid and potassium hydroxide quantities would be adjusted based on the actual raw material potency.

Example 3

A herbicidal formulation of the present invention was prepared with the following composition: Ingredient % w/v

Glyphosate Acid, 95% 58.0

Potassium Hydroxide, (commercial grade 85% pellet) 22.6

Surfactant System as per Formulation B above (60% active) 8.0

Purified Water q.s. to 100

The resulting formulation is a glyphosate herbicide formulation containing the potassium salt. The formulation was prepared in accordance with the method as described in example 2 above (without the addition of the antifoam). The resulting formulation contains about 551 g/L glyphosate acid and about 48 g/L total active surfactant (the surfactant system comprising about 42 g/L alkylpolyglycoside surfactant and about 6.2 g/L betaine surfactant).

Example 4

The resulting formulation is a glyphosate herbicide formulation containing the potassium salt. The formulation was prepared in accordance with the method as described in example 2 above (without the addition of the antifoam). The resulting formulation contains about 551 g/L glyphosate acid and about 46 g/L total active surfactant (the surfactant system comprising about 38.5 g/L alkylpolyglycoside surfactant and about 7.76 g/L betaine surfactant). Example 5

The resulting formulation is a glyphosate herbicide formulation containing the potassium salt. The formulation was prepared in accordance with the method as described in example 2 above (without the addition of the antifoam). The resulting formulation contains about 551 g/L glyphosate acid and about 46 g/L total active surfactant (the surfactant system comprising about 38.5 g/L alkylpolyglycoside surfactant and about 7.76 g/L betaine surfactant).

Example 6

The resulting formulation is a glyphosate herbicide formulation containing the amine salt, monoisopropylamine. The formulation was prepared in accordance with the method as described in example 2 above except that monoisopropylamine was added to aqueous suspension of glyphosate acid with temperature kept below 30°C during the process. The resulting formulation contains about 551 g/L glyphosate acid and about 48 g/L total active surfactant (the surfactant system comprising about 42 g/L alkylpolyglycoside surfactant and about 6.2 g/L betaine surfactant).

Example 7

The resulting formulation is a glyphosate herbicide formulation containing the amine salt, monoisopropylamine. The formulation was prepared in accordance with the method as described in example 6 above. The resulting formulation contains about 551 g/L glyphosate acid and about 30 g/L total active surfactant (the surfactant system comprising about 26 g/L alkylpolyglycoside surfactant and about 3.9 g/L betaine surfactant). Example 8

The formulation was prepared by adding 16% (i.e., 16kg per 100L) batch size of water to a jacketed mixing vessel and cooling the water by circulating cold water via a chiller unit. The glyphosate acid was then added to the mixing vessel whilst mixing to form slurry. The potassium hydroxide pellet was carefully added to the mixture and paddle mixed until dissolved. The temperature was kept below 30°C during this process. Stoichiometric amount of monoisopropylamine (4.6%) was added slowly with mixing. Dow 1410 Antifoam was added with mixing. The pH of the mixture was then adjusted from 4.9 to 5.6 with the remaining amount of monoisopropylamine (6.4%). The surfactant system was premixed with the blue dye and was then slowly added whilst mixing. The batch was made to required volume with water. Mixing was continued for about 30 minutes until a homogenous solution was obtained. The pH of the product was 5.4. The resulting formulation contains a total of about 580 g/L glyphosate acid (which comprises of about 450 g/L glyphosate acid as the potassium salt and about 130 g/L glyphosate acid as the monoisopropylamine salt) and about 32 g/L total active surfactant (the surfactant system comprising about 27.8 g/L alkylpolyglycoside surfactant and about 4.1 g/L betaine surfactant). Example 9

The formulation was prepared by adding 5% batch size of water to a jacketed mixing vessel and cooling the water by circulating cold water via a chiller unit. 7% (i.e., 7kg per 100L batch) of required glyphosate acid wet cake was then added to the mixing vessel whilst mixing to form slurry. 10% (i.e., 4.8kg per 100L) of required potassium hydroxide solution was carefully added to the mixture and paddle mixed until dissolved. Dow 1410 Antifoam was added with mixing. The temperature was kept below 30°C during this process. The remaining quantity of glyphosate acid and potassium hydroxide solution were added alternatively in portions with mixing. The pH was now around 5.0. The surfactant system was premixed with the blue dye and was then slowly added whilst mixing. The batch was made to required volume with water. Mixing was continued for about 30 minutes until a homogenous solution was obtained. The pH of the product was 4.9. The resulting formulation contains a total of about 600 g/L glyphosate acid (as the potassium salt) and about, 33 g/L total active surfactant (the surfactant system comprising about 28.9 g/L alkylpolyglycoside surfactant and about 4.26 g/L betaine surfactant). Wetting Studies

Wetting tests were carried out to compare the wetting properties of some of the example herbicidal formulations above to commercially available herbicidal formulations. A - hydrophobic cotton piece (25mm x 25mm) was placed on the surface of the formulations. When the wetting of the cotton substrate was complete, the substrate sank into the formulation. The time required for complete wetting was recorded when the cotton piece started sinking in the formulation. The results of these studies are provided in Table 1.

At the lowest practical concentration (i.e. 2 g/L of glyphosate) in ready-to-use solutions, it was found that all three commercially available products X, Y and Z (with traditional high surfactant loading) did not exhibit significant wetting on the testing tapes. The herbicidal formulations of Examples 3 and 6 above provided good wetting properties (less than 20 minutes), and these formulations had reduced surfactant content at 48 g/L active surfactants. The herbicidal formulations of Examples 8 and 9 above (comprising high glyphosate concentrations and further reduced surfactant content at 33 g/L active surfactants) also provided adequate wetting properties.

At a 2-fold increase of the lowest practical concentration (i.e. 4 g/L of glyphosate) in ready- to-use solution, only product X showed good wetting. Products Y and Z still did not provide significant wetting. In contrast, the herbicidal formulations of Examples 3 and 6 above provided rapid wetting while the herbicidal formulations of Examples 8 and 9 above achieved good wetting.

Table 1. Wetting Time of Hydrophobic Cotton in Glyphosate Solutions

FORMULATION %V/V IN TAP WETTING TIME

WATER (MINUTES)

Ready-to-use concentration: 2g/L glyphosate acid

Example 3: 55 lg a.e./L 0.40 17

Example 6: 55 lg a.e./L 0.40 10

Example 8: 580g a.e./L 0.37 58

Example 9: 600g a.e/L 0.36 67

Product X ^*: 580g a.e./L 0.37 No significant wetting

Product Y ^**: 360g a.e./L 0.60 No significant wetting

Product Z 540g a.e./L 0.40 No significant wetting

Ready-to-use concentration: 4g/L glyphosate acid

Example 3: 55 lg a.e./L 0.80 3

Example 6: 55 lg a.e./L 0.80 3

Example 8: 580g a.e./L 0.74 11

Example 9: 600g a.e./L 0.72 10

Product X ^*: 580g a.e./L 0.74 18

Product Y ^**: 360g a.e./L 1.20 No significant wetting

Product Z 540g a.e./L 0.80 No significant wetting

^* Product X: 580g glyphosate acid/L as potassium and triethanolamine salts with built-in surfactant system containing alkylpolyglycoside

^** Product Y: 360g glyphosate acid/L as monoisopropylamine salt with built-in surfactant system containing ethoxylated alkyl amine

^*" Product Z: 540g glyphosate acid /L as potassium salt with built-in surfactant system containing ethoxylated alkyl amine Synergistic Effects

It has surprisingly been found that the herbicidal formulations of the invention, despite comprising a low loading of surfactants, are capable of achieving the same level or a higher level of herbicidal efficacy in comparison to similar commercially available herbicidal formulations comprising a much higher loading of surfactants.

It has been found that the components of the surfactant system of the present invention work together synergistically to provide the maximum adjuvant effect despite the low loading of surfactants, together with the optimum capacity to be incorporated into concentrated formulations without affecting the chemical and physical stability or viscosity of the formulation.

Due to the toxicity of ethoxylated alkyl amine type surfactants to both humans and the environment, the inventors conducted numerous studies with the object of providing an improved surfactant system for use in or with herbicidal formulations, particularly high strength glyphosate formulations. Surfactants other than ethoxylated alkyl amine type surfactants are commercially available for use with herbicidal formulations such as glyphosate formulations. Some examples include: GERONOL CF/AR (from Rhodia) which is an anionic surfactant comprising 70% ethoxylated alcohol phosphate ester; GERONOL CF/AS 50HL (from Rhodia) which comprises 50% ammonium quaternary compound; and BREAK-THRU G850 (from Evonik) which comprises 38% fatty acid amino alkyl betaine. Trials were carried out to evaluate the use of varying amounts of each of these surfactants with a highly concentrated herbicidal formulation of glyphosate potassium (540 g acid/L). It was found that none of these surfactants were compatible with the glyphosate formulation, as the samples were unstable, resulting in phase separation or gel formation in each of the samples. As a result, other commercially available surfactants were evaluated for use in a similar glyphosate herbicidal formulation. Details of these further studies are set out in Table 2 below. Table 2. Evaluation of Surfactants

Glyphosate Surfactant Observation

Potassium (1 drop unless otherwise stated)

550 - 580 g acid/L

4 drops Superwetter (organosilicone) cloudy

4 drops Soprophor FL cloudy

(ethoxylated polyarylphenol phosphate amine)

4 drops Alkamuls OR/36 (ethoxylated castor oil) cloudy

4 drops Alkamuls A (ethoxylated oleic acid) cloudy

4 drops Soprophor BSU (ethoxylated tristyryl phenol) cloudy

4 drops Rhodameen RAM/7 cloudy

4 drops Soprophor TSP/461 cloudy

4 drops Companion EWA11 cloudy

4 drops Synthecol Quad LF cloudy

4 drops Triton X-45 cloudy

4 drops POE Sorbitan Monooleate cloudy

4 drops Tergitol 15-S-9 cloudy

4 drops Terwet 3780 cloudy

4 drops Triton X-100 cloudy

4.2g + 0.5g water 0.2g Synthecol BT not miscible

(lauryl betaine)

4.2g + 1.2g water 0.2g Synthecol BT not miscible

(lauryl betaine)

4.2g + 1.8g water 0.2g Synthecol BT clear

(lauryl betaine)

11.7g + 0.6g water 1.5g Synthecol BT not miscible

(lauryl betaine)

9.5mL 0.2mL Glucopon 225 DK miscible

(alkylpolyglycoside)

11.7g (no water) 2.1 g Synthecol CAB not miscible

(cocoamidopropyl betaine)

9.5mL 4 drops Synthecol CAB not miscible

(cocoamidopropyl betaine)

9.5mL 4 drops Geropon SDS (sodium sulfosuccinate) not miscible After these results Synthecol BT was combined with Geronol CF/AR for evaluation. The results are provided in Table 3 below. These two surfactants were found to be miscible with each other. However when the surfactant mixture was added to a herbicidal formulation of glyphosate potassium, the resultant formulation was only miscible when the ratio of Synthecol BT to Geronol CF/AR was 1:2. The total surfactant content was about 6% as is. Wetting tests were conducted to evaluate the wetting properties of the miscible formulation. However the formulation did not provide significant wetting on the hydrophobic cotton even when it was diluted to up to 4% w/v in water.

Table 3. Evaluation of Synthecol BT and Geronol CF/AR

The wetting properties of the glyphosate formulation containing Glucopon 225 DK as shown in Table 2 were then evaluated. The results are shown in Table 4 below. Table 4. Wetting Properties of Glucopon 225 DK Surfactant

Samples of the individual alkylpolyglycoside and alkylbetaine surfactants and their combinations in tap water were then prepared for evaluation. Wetting tests were carried out for comparison of the surfactants' wetting properties. A hydrophobic cotton piece (25mm x 25mm) was put on the surface of the prepared surfactant solutions. When the wetting of the cotton substrate was complete, the substrate sank into the solution. The time required for complete wetting was recorded when the cotton piece started sinking in the solution. The results of these studies are provided in Table 5 below.

The results in Table 5 show that a low level of alkylbetaine (0.15g/L) on its own was not a good wetting agent. Similarly, a low level of alkylpolyglycoside (0.2 g/L) on its own did not provide significant wetting for the hydrophobic substrate. However, addition of only a very small amount of alkylbetaine (0.005 g/L) surprisingly resulted in an improved wetting of the hydrophobic substrate, with wetting completed in 52 minutes. Further addition of a small amount of alkylbetaine (to 0.067 g/L) resulted in a huge reduction in wetting time to 6 minutes. Addition of 0.15 g/L of alkylbetaine surfactant to 1 g/L of alkylpolyglycoside surfactant significantly reduced the wetting time of the hydrophobic substrate by over 60%.

Table 5. Wetting Time of Hydrophobic Cotton in Alkylpolyglycoside and Alkylbetaine Surfactants

These results show that the combination of alkylpolyglycoside surfactant and alkylbetaine surfactant has a synergistic effect on the wetting time of the hydrophobic substrate. The synergy of this combination of surfactants means that the surfactant system can be used in herbicidal formulations to significantly reduce the surfactant loading in the formulation, yet still provide rapid wetting of the vegetation after application of the formulation to sufficiently enhance the herbicidal efficacy of the formulation. The surfactant system of the invention, comprising one or more alkylpolyglycosides and one or more alkylbetaines and/or alkyl(amidoalkyl)betaines, within a certain ratio of alkylpolyglycoside to betaine, provides a highly efficient surfactant system, particularly to high strength aminophosphate and aminophosphonate herbicidal formulations. At less than 90 g/L total surfactant loading, stable formulations of aminophosphate and aminophosphonate herbicides with a concentration of at least 540 g/L can be made, without adversely affecting the physical or chemical stability of the formulations. The efficacy of these formulations is at least similar to or better than that achieved by similar commercially available herbicidal formulations. This is a significant advance in the art that could not have been predicted from prior knowledge of these surfactants.

In field use the formulations of the invention are highly desirable as they can provide delivery of high concentrations of herbicide to unwanted vegetation in a relatively small amount and with very low surfactant loading, making them safer and easier to use, less toxic and less harmful to the environment.

Stability Trials

The stability of the formulations described in examples 2 to 9 above were studied under accelerated conditions in order to estimate an appropriate shelf life for the products of the present invention. This accelerated stability trial was conducted at 54°C for 14 days and 4°C for 14 days. A stable formulation under these conditions normally supports a two year ambient temperature shelf-life. lOOmL samples of the formulations were subjected to a formal stability study with reference to the New Zealand ACVM Registration Standard and Guideline for Chemistry of Plant Compounds (23 ACVM 06/05). The test methodology was as described by the Collaborative International Pesticides Analytical Council (CIPAC).

The results showed that all of the samples retained good physical and chemical stability for the duration of the stability trial. No phase separation or precipitation was observed. There was no significant change in the visual appearance of the formulations, the density of the formulations, the chemical assay of glyphosate in the formulations, or the pH of the formulations after the accelerated stability trials. This essentially demonstrates that the formulations are chemically and physically stable and that they should have a minimum two year ambient shelf-life. ADVANTAGES

The main advantage of the surfactant system of the present invention is that only a very small amount of the surfactant system is required in order to achieve the same level or higher level of herbicidal efficacy in comparison to current commercially available surfactant formulations and/or herbicidal formulations. Such a low loading of surfactant would usually be considered inadequate to give reliable enhancement of herbicidal efficacy however the surfactant system of the present invention achieves an excellent level of biological activity, due to the synergism between the particular combinations of surfactants. Accordingly, the surfactant system of the invention can be included in a herbicidal formulation or be used as an adjuvant to a herbicidal formulation in significantly lower concentrations than other surfactants or surfactant systems.

The surfactant system of the present invention is particularly suitable for use in or with high concentration herbicide formulations such as high concentration glyphosate formulations which have traditionally required a high loading of surfactants. Despite the lower loading of surfactants, the herbicidal formulations still exhibit the required degree of physical and chemical stability, and they are of suitable viscosity to enable easy application.

The formulations of the present invention are less hazardous and less toxic compared to other formulations of or comprising known surfactants and surfactant systems. The components of the surfactant system of the invention are readily biodegradable and are of low toxicity, therefore making them safe to use and environmentally friendly.

In addition, cost advantages can be realised due to the reduced amount of surfactant system required. Further advantages in terms of transport, storage, handling and container disposal are also realised due to the ability to produce an effective high concentration herbicidal formulation in a smaller liquid volume. VARIATIONS

It will be appreciated that the formulations presented in examples 1 to 9 above are examples only and that other formulations are contemplated without departing from the spirit and scope of the invention. For example, the surfactant system of the invention may include different surfactants from the general classes of surfactants described, and in a different ratio than those exemplified. In addition, the surfactant system may include other suitable additives and/or excipients.

Although the formulations of examples 2 to 9 refer to glyphosate herbicide formulations, it is envisaged that different types of herbicides may be used as the active ingredient in the formulations without departing from the spirit and scope of the invention. Furthermore, it will be appreciated that the herbicidal formulation may further include more than one herbicidal active ingredient, or other additional agrochemicals. The herbicidal formulations may also include other additives and/or excipients which are capable of being incorporated in the formulation without adversely affecting the chemical or physical stability of the formulation. For example, additional additives and/or excipients may be included within the formulations of the present invention to tailor them to suit a specific administration method or a specific weed species to be treated.

It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is hereinbefore described.

It is to be further understood that even though numerous characteristics and advantages of the various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and functioning of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail so long as the functioning of the invention is not adversely affected.

Claims

A surfactant system for use in a herbicidal formulation or for use as an adjuvant to a herbicidal formulation, the surfactant system comprising at least one surfactant selected from the group comprising alkylpolyglycosides and at least one surfactant selected from the group comprising alkylbetaines and alkyl(amidoalkyl)betaines.

A surfactant system as claimed in claim 1, wherein the ratio of alkylpolyglycoside surfactant to alkylbetaine or alkyl(amidoalkyl)betaine surfactant is from about 3 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 40 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active content of the surfactant.

A surfactant system as claimed in claim 2, wherein the ratio of alkylpolyglycoside surfactant to alkylbetaine or alkyl(amidoalkyl)betaine surfactant is from about 5 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant to about 9 parts by weight of alkylpolyglycoside surfactant per 1 part by weight of alkylbetaine or alkyl(amidoalkyl)betaine surfactant, expressed as active content of the surfactant.

A surfactant system as claimed in any one of the previous claims, wherein the amount of alkylpolyglycoside surfactant present in the surfactant system is in the range of about 35 - 70% w/w as active surfactant.

A surfactant system as claimed in any one of the previous claims, wherein the amount of alkylbetaine or alkyl(amidoalkyl)betaine surfactant present in the surfactant system is in the range of about 1 - 20% w/w as active surfactant.

6. A herbicidal formulation comprising at least one active herbicidal ingredient and a surfactant system as claimed in any one of the previous claims.

7. A herbicidal formulation as claimed in claim 6, wherein the active herbicidal ingredient is N-phosphonomethylglycine, in the form of one or more of its water soluble salts.

8. A herbicidal formulation as. claimed in claim 7, wherein the active herbicidal ingredient is present in a concentration of greater than 510 g/L.

9. A herbicidal formulation as claimed in any one of claims 6 - 8, wherein the total content of the surfactant system in the herbicidal formulation is less than 90 g/L, expressed in active content of surfactants.

10. A concentrated aqueous herbicidal formulation comprising one or more water soluble salts of N-phosphonomethylglycine, and a surfactant system as claimed in any one of claims 1 - 5, wherein the N-phosphonomethylglycine is present in an amount of at least 540 g/L, and the total content of the surfactant system in the formulation is less than 80 g/L, expressed in active content of surfactants.

11. A method of controlling unwanted vegetation comprising applying to the vegetation an effective amount of the herbicidal formulation as claimed in any one of claims 6 - 10.

12. A method of controlling unwanted vegetation comprising obtaining or preparing a surfactant system as claimed in any one of claims 1 - 5, adding a herbicidally enhancing amount of the surfactant system to a herbicidal formulation comprising at least one active herbicidal ingredient, and applying an effective amount of the herbicidal formulation to the unwanted vegetation.

13. A method as claimed in claim 11 or 12, wherein the herbicidal formulation is diluted with water prior to application.