WO2023244128A1

WO2023244128A1 - Liquid suspension concentrate and methods of manufacture and use

Info

Publication number: WO2023244128A1
Application number: PCT/NZ2023/050060
Authority: WO
Inventors: Karen Yeritsyan
Original assignee: Donaghys Limited
Priority date: 2022-06-17
Filing date: 2023-06-16
Publication date: 2023-12-21
Also published as: AR129637A1

Abstract

A liquid suspension concentrate is described herein comprising, in the concentrate, two triazine herbicide compounds being hexazinone and terbuthylazine along with water immiscible solvent. Methods of manufacturing and use of the above concentrate are also described. The liquid suspension concentrate offers a dual active product that is stable for extended periods of time and even retains stability when diluted prior to application and stored in a diluted form.

Description

LIQUID SUSPENSION CONCENTRATE AND METHODS OF MANUFACTURE AND USE

RELATED APPLICATIONS

This application derives priority from Australia patent application number 2022901646 filed on 17 June 2022 with WIPO DAS code 4AE9 and Australia patent application number 2022902164 filed on 2 August 2022 with WIPO DAS code 9DB8, both of which are incorporated herein by reference.

TECHNICAL FIELD

Described herein is a liquid suspension concentrate comprising, in the concentrate, two triazine herbicide compounds being hexazinone and terbuthylazine. Methods of manufacturing and use of the above concentrate are also described.

BACKGROUND ART

Stabilising herbicide compounds in one suspension concentrate can be challenging. Such herbicide compounds when mixed may be inherently incompatible, for example, due to varying physical properties. This may make the manufacture, storage and use of such mixtures challenging or impossible without compromising stability. Common problems in the art relate to precipitation of different compounds, active agent degradation and even active agent reactions in storage leading to poor end outcomes.

Triazine herbicide compounds broadly have a planar six-membered benzene like structure however, three carbons are replaced by nitrogen atoms. There are three different isomers of triazine distinguished by where the nitrogen atoms are located in the compound.

Terbuthylazine is one form of triazine being a selective residual herbicide for grass and broadleaf weed control. It is used in forestry, maize, sweet corn, peas, certain orchard crops, and for long-term non- selective weed control in non-crop situations. Terbuthylazine belongs to the s-triazine chemical family which includes many herbicides widely used in agriculture practice for pre-emergence and postemergence weed control. The comparatively low cost and broad-spectrum activity of terbuthylazine has led to this herbicide having a wide range of applications in New Zealand's arable cropping scene. This use has been both on-label and off-label such as for cereal crops. Use in a similar manner may have occurred in other countries.

Terbuthylazine herbicide is taken up by the roots of weed plant seedlings and to some extent by the emerging cotyledons.

Hexazinone is another form of s-triazine which is a contact and residual herbicide. It is also understood to be absorbed by leaves and the roots of plants. In forestry, it is most commonly used for site preparation and for conifer release. Hexazinone is tolerated by conifers, thus it is a very effective herbicide in forestry for reducing competition to growing conifer trees from weeds and other broad leaf woody species.

Due to their low aqueous solubility, triazines do not significantly penetrate to lower levels of the soil and consequently they have little effect on deep rooted crops or weeds.

Triazine herbicide compounds influence plant growth by:

Inhibition of photosynthetic pathways;

Blockage of carbon fixation, in essence starving the plant tissue;

Oxidation of chlorophyll and membrane lipids.

Terbuthylazine and hexazinone triazine compounds are used in combination in New Zealand forestry to control a range of competitive weed species during the first year after planting Pinus Radiata. Other use may occur in other countries. The key attributes of these two herbicides, which underpin their value to the New Zealand forestry sector are:

1. The selectivity of these herbicides to P. radiata and not causing phototoxic damage to P. radiata; and,

2. The persistence of these herbicides that provides activity, following either aerial or spot treatment, to reduce weed growth for up to one year.

These attributes are particularly relevant to the control of some of the more competitive weeds that occur on forest plantations.

A number of art commercial formulations exist for triazine herbicides used in forestry operations but these are based on single active ingredients. Examples of suspension concentrates containing terbuthylazine include: Terb 500™ by Lonza NZ Ltd, Agpro Terbuthylazine 500™, Terbaflo™ by Ravensdown, Assett Herbicide™ by Orion AgriScience, Timberwolf 500SC™ by Kenso NZ.

Water dispersible granule products containing terbuthylazine alone can also be purchased currently. Examples include: Timberwolf 900WG™ by Kenso NZ.

The main commercially available products containing hexazinone are single active water dispersible granule products and not suspension concentrates Examples of hexazinone containing granule products currently available include: Hexazinone 750WG™ by Adria, Viper™ by Orion AgriScience, and Vel-Ken 900WG™ by Kenso NZ.

In general, combination concentrate formulations may be preferable. This is due to convenience as the end user does not need to mix two single active products to obtain a multi-active solution. Simply mixing multiple active compounds may not however be simple. To anyone experienced in art, it is well known that mixing different compounds to prepare a working solution may come with significant complications due to possible incompatibility of used formulations. Such incompatibility may result in either precipitation, phase separation, flocculation and/or other negative effects that may cause issues with product dispersion, product waste, poor herbicidal activity, and potentially discarded product. Attempts have been made to mix triazine compounds.

For example terbuthylazine and hexazinone are sold as a combined product, examples including: Timberwolf Xtra™ by Kenso NZ which contains 435g/L terbuthylazine and 65g/L hexazinone, and Release KT Herbicide™ by Orion AgriScience which contains 425g/L terbuthylazine and 75g/L hexazinone. These products however, are essentially made from two separate single active compositions that are mixed together when an order is received and which are shipped for immediate use. The lifetime of the combined concentrate may be limited before the combined concentrate separates or otherwise becomes unstable. This is not ideal and has been a drawback to production and sales of any truly commercial combined product.

China patent publication no. CN10408230A in the English machine translation has some description around producing terbuthylazine and hexazinone suspensions. One example suspension described comprises both actives along with dispersant, wetting agent, defoamer, thickener and antifreeze. The suspensions described in CN10408230A lack the presence of a water immiscible solvent, a key compound identified by the inventor that assists with multi-active agent stability. As a result, the suspensions of CN10408230A have a similar problem to art products where the diluted terbuthylazine and hexazinone combination must be used quickly otherwise the actives separate and are not able to be re-dispersed leading to product loss/waste.

As may be appreciated from the above, it may be useful to produce stable triazine containing liquid suspension concentrates, or at least provide the public with another choice of multiple activity triazine suspension concentrate.

Further aspects and advantages of the liquid suspension concentrate and methods of manufacture and use will become apparent from the ensuing description that is given by way of example only.

SUMMARY

Described herein is a liquid suspension concentrate comprising, in the concentrate, two triazine herbicide compounds being hexazinone and terbuthylazine. Methods of manufacturing and use of the above concentrate are also described. The liquid suspension concentrate offers a dual active product that may be stable for extended periods of time and even retains stability when diluted prior to application.

In a first aspect there is provided a liquid suspension concentrate comprising:

3-cyclohexyl-6-(dimethylamino)-l-methyl-l,3,5-triazine-2,4(lH,3H)-dione (hexazinone);

N-tert-butyl-6-chloro-N'-ethyl-l,3,5-triazine-2,4-diamine (terbuthylazine); and water immiscible solvent.

In a second aspect, there is provided a liquid suspension concentrate comprising: terbuthylazine; hexazinone; water immiscible solvent; a first dispersing agent comprising condensed methyl naphthalene sulfonate sodium salt; wetting agent; and a further dispersing agent comprising block copolymer dispersant.

In a third aspect, there is provided a liquid suspension concentrate comprising: terbuthylazine 97% purity; hexazinone 98% purity; water immiscible solvent; condensed methyl naphthalene sulfonate sodium salt; ethoxylated alcohol; block copolymer dispersant; monopropylene glycol; xanthan gum; preservative; antifoaming agent; and water.

In a fourth aspect, there is provided a liquid suspension concentrate comprising:

35-50%w/v terbuthylazine 97% purity;

5.0-15%w/v hexazinone 98% purity;

0.5-10%w/v water immiscible solvent;

1.5- 3.5% w/v condensed methyl naphthalene sulfonate sodium salt;

1.5-3.0%w/v ethoxylated alcohol;

1.0-3.5%w/v block copolymer dispersant;

5-10%w/v monopropylene glycol;

0.15-0.25%w/v xanthan gum;

0.05-0. l%w/v preservative;

0.1-1.0%w/v antifoaming agent; and to 100% water.

In a fifth aspect, there is provided a diluted liquid suspension comprising: a liquid suspension concentrate comprising: terbuthylazine, hexazinone, water immiscible solvent, first dispersing agent, wetting agent, further dispersing agent; and water; wherein water is added at a ratio of 1 part liquid suspension concentrate to 1 to 100 parts water.

In a sixth aspect, there is provided a method of manufacturing a liquid suspension concentrate comprising hexazinone and terbuthylazine by: mixing together carrier, water immiscible solvent, first dispersing agent, wetting agent, further dispersing agent; adding hexazinone and terbuthylazine; mixing until all solid ingredients are wetted to produce a formed liquid; milling the formed liquid to produce formed particles; adding further carrier to the formed particles under constant agitation to form a liquid suspension concentrate.

In a seventh aspect, there is provided a method of use comprising: selecting a liquid suspension concentrate substantially as described above; applying the liquid suspension concentrate to an area to be treated; wherein the area to be treated comprises: a target plant, the target plant being substantially unaffected by the liquid suspension concentrate; and a plant or part thereof affected by the active compounds in the liquid suspension concentrate in a way that slows or kills growth of the plant or part thereof.

The liquid suspension concentrate described may provide a number of advantages including dual delivery in one concentrate of two herbicidal active compounds. There may be no need to measure out specific amounts of either individual composition and mix these individual compositions and then have a finite short time life before use. The liquid suspension concentrate may be diluted and stored and later re-dispersed easily and subsequently used. This may avoid waste of diluted liquid suspension from caking and separation post dilution. Further, the concentrate described may overcome a long standing problem in the art of needing to separate these active compounds due to their varying properties and, at best, mix and use quickly. To the inventor's knowledge, no long term stabile suspension concentrate is on the market despite the commercial benefits such a product would provide. Further benefits are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the liquid suspension concentrate and methods of manufacture and use will become apparent from the following description that is given by way of example only and with reference to the accompanying drawings in which:

Figure 1 illustrates a photo of three samples of liquid suspension concentrate post re-dispersion after storage for 10 hours where: Trial Formulation 1 is Formulation 1 from Example 2 including water miscible solvent; Trial Formulation 2 is Formulation 1 of Example 2 without water immiscible solvent; and Trial Formulation 3 is Example 12 from art publication CN104082308A;

Figure 2 illustrates a photo of three samples of Trial Formulations 4, 5 and 6 using, as water immiscible solvent, Recosol D60™ (Trial Formulation 4); toluene (Trial Formulation 5); and Solvent C9™ (Trial Formulation 6). The photos show the re-dispersion findings for these different water immiscible solvents;

Figure 3 illustrates a photo of three samples of Trial Formulations 7, 8 and 9 using varying concentrations of water immiscible solvent and exchanged first dispersing agent where: Trial Formulation 7 uses 0.5% w/v water immiscible solvent; Trial Formulation 8 uses 10% w/v water immiscible solvent; and, Trial Formulation 9 uses 1% w/v/ water immiscible solvent and sodium lignosulfonate as the first dispersing agent;

Figure 4 illustrates a photo of Trial Formulation 7 inverted additional times (total 10 times) to cause re-dispersion;

Figure 5 illustrates photos of the liquid suspension concentrate tested at time 0 [A], after 8 days

[B], after 11 days [C], after 19 days [D], after 27 days [E] and after 28 days [F]; and

Figure 6 illustrates a photo of three samples of liquid suspension concentrate diluted with water and pictured side by side post inversion after a storage stability trial.

DETAILED DESCRIPTION

As noted above, described herein is a liquid suspension concentrate comprising, in the concentrate, two triazine herbicide compounds being hexazinone and terbuthylazine. Methods of manufacturing and use of the above concentrate are also described. The liquid suspension concentrate offers a dual active product that is stable for extended periods of time and even retains stability when diluted prior to application. More advantages are described further below. For the purposes of this specification, the term 'about' or 'approximately' and grammatical variations thereof mean a quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length that varies by as much as 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% to a reference quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length.

The term 'substantially' or grammatical variations thereof refers to at least about 50%, for example 75%, 85%, 95% or 98%.

The term 'comprise¹ and grammatical variations thereof 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.

Liquid Suspension Concentrate

In a first aspect there is provided a liquid suspension concentrate comprising:

Actives

As noted above, the liquid suspension concentrate comprises both the s-triazine compounds hexazinone and terbuthylazine mixed together in one liquid suspension as a concentrate.

The liquid suspension concentrate may comprise l-20%w/v hexazinone and 10-50%w/v terbuthylazine. Note that these amounts may vary depending on the purity of the triazine compounds prior to addition to the liquid suspension concentrate. For example, if the purity of a triazine compound is less than 90%, more triazine compound may be needed to form the liquid suspension concentrate than for a 97-99% purity triazine compound. Water Immiscible Solvent

As noted above, the liquid suspension concentrate comprises water immiscible solvent. The water immiscible solvent may be present as one compound or multiple compounds. Reference to singular or plural is not intended to be limiting with respect to the water immiscible solvent.

Water immiscible solvent was found by the inventor to avoid or minimise caking and precipitation issues in the art associated with dual active suspensions using terbuthylazine and hexazinone. This avoidance of caking was particularly unexpected and surprising as the use of water immiscible solvent meant that concentrates, even diluted to working solutions and left undisturbed for prolonged periods of time, either did not form caking or were very easily re-dispersed into suspension once caking had formed. Diluted concentrates without water immiscible solvent present did not re-disperse once diluted as is a known and longstanding problem in art. This inability to re-disperse diluted concentrates of this nature has led to existing handling guidelines of keeping the actives separate or mixing the actives at use and then using quickly prior to caking occurring. Once caking occurs, the product must be disposed of.

Trials completed by the inventor highlighted the requirement of using water immiscible solvent. Diluted concentrate samples prepared without water immiscible solvent produced non-dispersible caking/precipitates after as little as 4 hours post dilution.

The mechanism of how water immiscible solvent improves storage stability is not known to the inventor for certain. Without being bound by theory, the inventor has found that water immiscible solvent appears to add "slipperiness" to suspended particles in the suspension preventing these particles from strongly binding with each other to form larger agglomerates. As a result, the particles are easily redispersed should any caking/precipitation form. The inventor also understands that use of water immiscible solvent would likely contribute to the overall physical stability of the liquid suspension concentrate, especially at low temperatures. This may be another reason why the water immiscible solvent acts so effectively to address caking and re-dispersion.

The water immiscible solvent may be selected based on the ability of the water immiscible solvent contributing a "slipperiness" to the solid particles in the suspension.

The water immiscible solvent may be an organic solvent.

The water immiscible solvent may have a low viscosity similar to water. The low viscosity may be below 10mm²/s @25°C.

Choice of water immiscible solvent may also be influenced by factors such as material cost or handling characteristics such as the water immiscible solvent flash point, environmental 'friendliness' or compatibility, and hazardous properties. The water immiscible solvent may be selected from: naptha aromatic solvent, kerosene, white spirits, turpentine, isopropyl myristate, isophorone, toluene, other aromatic hydrocarbon compounds, and combinations thereof. Examples of aromatic hydrocarbons may be Recosol D60™ and Solvent C9™

Solvent naphtha aromatic may be a useful water immiscible solvent due to the wide availability and cost effectiveness of this water immiscible solvent. As noted above and elsewhere in this specification, other water immiscible solvents may be used and reference to solvent naphtha aromatic should not be seen as limiting.

The concentration of water immiscible solvent in the liquid suspension concentrate may be from 0.5 to lOw/v, or from 0.5 to 5w/v, or from 0.5 to 2w/v, or approximately 1.0%w/v. This range and the amount of approximately 1.0% w/v is based on the inventor's experience of testing varying concentrations of water immiscible solvent and still obtaining easy re-dispersion of any caking post dilution and storage. The exact amount of water immiscible solvent may differ within this range depending on the extent of dilution and type of water immiscible solvent chosen however, this range appears to be an optimum. At 0.5% w/v, the extent of caking and ability to re-disperse the cake becomes more difficult which is thought to be due to the particles in the suspension (and cake formed) having insufficient 'slipperiness'. Any lower concentration of water immiscible solvent would likely impair or prevent re-dispersion.

Higher amounts of water immiscible solvent (above 1.0% w/v) may allow the diluted concentrate to be re-dispersed once caking occurs and the exact optimal amount will be in this range up to 10% w/v. More water immiscible solvent could be added however, the benefit is negated and higher additions simply add extra cost and material use hence, are not optimal. At amounts over 10% w/v, it is envisaged that oil/water phase separation could occur which is also not desirable. Lower amounts of water immiscible solvent may also minimise any handling issues, avoid flammability and avoid strong smells from the water immiscible solvents.

Stability

The liquid suspension concentrate described above is stable. Stability in this context refers to the liquid suspension remaining in suspension over time under ambient conditions over time.

The liquid suspension concentrate may be stable under accelerated stability conditions of 54°C for at least 14 days.

The liquid suspension concentrate may be stable when left for at least 28 days at ambient temperature and pressure.

The liquid suspension concentrate may be configured to be sufficiently stable to support at least 2 years shelf life.

Shelf life may be tested according to CIPAC recommendations for suspension concentrates or other methods. First Dispersing Agent

The liquid suspension concentrate may comprise a first dispersing agent. The first dispersing agent may be a polymeric anionic dispersing agent. The first dispersing agent may be condensed methyl naphthalene sulfonate sodium salt.

The first dispersing agent may comprise 0.5-20%w/v, or 0.5% to 10%w/v, or 0.75 to 7.5%w/v, or 0.5% to 5%\N/\I, or 1.5-3.5%, or 0.75-2.5%w/v, or approximately 2%w/v of the liquid suspension concentrate.

Wetting Agent

The liquid suspension concentrate may comprise a wetting agent/surfactant, referred to hereafter as a wetting agent. The wetting agent may be an ethoxylated alcohol. The wetting agent may be ethoxylated isodecyl alcohol.

The concentration of wetting agent may be from 0.25-10%w/v, or l-5%w/v, or 1.5-3%w/v of the liquid suspension concentrate.

Further Dispersing Agent

The liquid suspension concentrate may comprise a further dispersing agent. The further dispersing agent may be a block copolymer dispersant. The block copolymer dispersant may be selected from: acrylic polymer amine salt; hydrophobically modified acrylic copolymer; polyacrylic acid and partly neutralised sodium salt; and combinations thereof.

The concentration of further dispersing agent may be from 0.25-7%w/v, or 0.5-5%w/v, or l-3.5%w/v of the liquid suspension concentrate.

Anti-Freezing Agent

The liquid suspension concentrate may comprise anti-freezing agent. The anti-freezing agent may be a glycol compound. The anti-freezing agent may be monopropylene glycol.

The concentration of anti-freezing agent may be from 5-10%w/v of the liquid suspension concentrate.

Antifoaming Agent

The liquid suspension concentrate may comprise antifoaming agent.

The concentration of antifoaming agent may be approximately 0.1-1.0%w/v of the liquid suspension concentrate. Thickener

The liquid suspension concentrate may comprise thickener/stabilizing agent, referred to hereafter as thickener. The thickener may be a gum or alginate compound. The thickener may be xanthan gum.

The concentration of xanthan gum may be approximately 0.15 to 0.25%w/v of the liquid suspension concentrate.

Preservative

The liquid suspension concentrate may comprise preservative. The preservative may be a selected from: quaternary ammonium compounds, salts, alcohols, and combinations thereof.

The concentration of preservative may be approximately 0.05 to 0.1%w/v of the liquid suspension concentrate.

Carrier

The liquid suspension concentrate may comprise a carrier. The carrier may be liquid, gel, or semi-solid in viscosity and form. The carrier may be an aqueous carrier. The liquid suspension concentrate may be an aqueous suspension. The carrier may be water.

Carrier may be added to volume or 100%. In practice, the amount of carrier added, if the carrier is water may be from 35-50%w/v, or from 40-45%w/v. This amount of carrier may vary depending on the carrier type and amount of other compounds used to form the liquid suspension concentration.

35-50%w/v terbuthylazine 97% purity;

5.0-15%w/v hexazinone 98% purity;

0.5-10%w/v water immiscible solvent;

1.5- 3.5% w/v condensed methyl naphthalene sulfonate sodium salt;

1.5-3.0%w/v ethoxylated alcohol;

1.0-3.5%w/v block copolymer dispersant;

5-10%w/v monopropylene glycol;

0.15-0.25%w/v xanthan gum;

0.05-0. l%w/v preservative;

0.1-1.0%w/v antifoaming agent; and to 100% water.

Viscosity

The liquid suspension concentrate may have a viscosity of 700-75,000, or 35,000-55,000, or 40,000- 50,000, or 40,000 to 45,000mPa.s when measured with Brookfield viscometer, Spindle 3.

Diluted Liquid Suspension

In a fifth aspect, there is provided a diluted liquid suspension comprising: a liquid suspension concentrate comprising: terbuthylazine, hexazinone, water immiscible solvent, first dispersing agent, wetting agent, further dispersing agent; and aqueous carrier; wherein aqueous carrier is added at a ratio of 1 part liquid suspension concentrate to 1 to 100 parts aqueous carrier. Aqueous Carrier

The aqueous carrier may be water.

Diluted Stability

The diluted liquid suspension may not form a cake of precipitated solids when no agitation is applied for at least 24 hours.

The diluted liquid suspension may not form a hard to disperse cake for at least 3 weeks post dilution with water.

The diluted liquid suspension may be sufficiently stable so that gentle mixing will re-suspend any solids that may form over time.

Method of Manufacture

Additional Compounds

Antifoaming agent may be added to the carrier, water immiscible solvent, first dispersing agent, wetting agent, further dispersing agent.

Preservative may be added with the further carrier to the formed particles.

Thickener and anti-freezing agent may also be added with the further carrier to the formed particles.

Thickener may first be dispersed in the anti-freezing agent prior to addition to the further carrier.

Optionally, the liquid suspension concentrate produced may be adjusted to a desired concentration by adding additional carrier. Initial Form

The carrier, antifoaming agent, wetting agent, water immiscible solvent, preservative and anti-freezing agent where used in the above method, may be in liquid form prior to manufacture of the liquid suspension concentrate.

The first and further dispersing agents, hexazinone, terbuthylazine and thickener may be in dry form prior to manufacture of the liquid suspension concentrate e.g. powder or granule.

Wetted

For the purposes of this specification, the term 'wetted' or grammatical variations thereof in the context of the above method, refers to the mixture being visually homogenous and evenly mixed together.

Milling

Milling comprises passing the formed liquid (water, surfactants, dispersants, active ingredients) through a bead or other mill. Milling may decrease individual particle size to micron size. The micron size may be less than or equal to 10 microns. This milling step may also improve wetting of solid particles by the wetting agent and water.

Ambient Conditions

The above method may be completed under ambient conditions. No temperature changes are required. No pressure or humidity or other atmospheric changes are required during the manufacturing method.

Method of Use

In a seventh aspect, there is provided a method of use comprising: selecting a liquid suspension concentrate substantially as described above; applying the liquid suspension concentrate to an area to be treated; wherein the area to be treated comprises: a target plant, the target plant being substantially unaffected by the liquid suspension concentrate; and a plant or part thereof affected by the active compounds in the liquid suspension concentrate in a way that slows or kills growth of the plant or part thereof. Application Dilution, Rate, Timing and Ratio

The liquid suspension concentrate may be diluted prior to application or applied in a concentrate form.

The liquid suspension concentrate may be applied at an application rate corresponding to existing art rates of application for the individual compounds.

The liquid suspension concentrate may be applied at varying times during a plant growth cycle. For example, the liquid suspension concentrate may be applied to plants and surrounding substrate (e.g. ground or soil), prior to target plant growth. This may be done to slow or kill existing plant growth to allow the target plant growth to occur. Alternatively, the liquid suspension concentrate may be applied to plants and surrounding substrate during a dormant growth phase for the plant(s), for example during winter. Alternatively, the liquid suspension concentrate may be applied to plants and surrounding substrate during an active growth phase for the plant(s), for example during summer.

The ratio of each active agent in the liquid suspension concentrate may vary. For example, the ratio terbuthylazine to hexazinone in the liquid suspension concentrate may vary depending on the timing of application. For example, the ratio of terbuthylazine to hexazinone in the liquid suspension concentrate when used in summer or an active plant growing time period may vary from the ratio of terbuthylazine to hexazinone in the liquid suspension concentrate when used in winter or a dormant plant growing time period.

Plants or Part of a Plant

The plants or parts of a plant to which the liquid suspension concentrate may be applied may be the foliar, stem or root portions of a plant or part thereof.

Plant types suitable for use with the liquid suspension concentrate described may be varied. Use may be to control competitive growth from surrounding plants to allow the target plants to grow. Target plants that may be unaffected by the liquid suspension concentrate where preferential growth may be useful may include plants selected from: forestry plants, cereal crops, orchard crops, nitrogen fixing crops, and combinations thereof.

More specific examples of target forestry plants for which preferential growth may be useful may comprise: pine species, eucalyptus species, fir species, oak species, redwood species, acacia species, poplar species, conifer species, and combinations thereof.

More specific examples of cereal crop plants may comprise species of: maize, oat, rice, wheat, rye, buckwheat, barley, sorghum, millet, quinoa, and combinations thereof.

More specific examples of orchard crop plants may comprise species of fruit or nut trees. More specific examples of nitrogen fixing crop plants may comprise species of: alfalfa (also known as Lucerne), clover crops, soybean crops, pea crops, bean crops, chickpea crops, peanut crops, and combinations thereof.

The inventor's understand that the described stability relates to the suspended particles not forming larger aggregates to cake together. Aggregation is understood to be avoided by

Sufficient wetting during manufacture;

Use of water immiscible solvent as described above leads to a "slipperiness" to suspended particles in the suspension preventing these particles from strongly binding with each other to form larger agglomerates and as a result, any caking that occurs may easily be redispersed;

Selection of suitable dispersants/surfactants as described above which causes the suspended solid particles to be surrounded by charge carrying molecules/ions, that push each other away due to having the same charge; and

If the stabilizing system is selected correctly as described, there may be sufficient viscosity in the concentrate (and diluted concentrate) to keep the dispersed particles in suspension.

The liquid suspension concentrate described may provide a number of advantages including:

Dual delivery in one concentrate of two herbicidal active compounds;

There may be no need to measure out specific amounts of either individual composition and mix these individual compositions and then have a finite short time life before use;

The concentrate described may overcome a long standing problem in the art of needing to separate these active compounds due to their varying properties and, at best, mix and use quickly. No long term stabile suspension concentrate is on the market despite the commercial benefits such a product would provide;

The concentrate may be reduced in volume being a concentrate hence minimises the cost of transport of the concentrate through avoiding transport of water;

The concentrate may be very stable over time even under challenging conditions;

Diluted solutions ready for application may be stored for prolonged periods of time without risk of forming hard cakes if application has to be interrupted for some reason (for example wind, faults with equipment, etc.). This means no diluted solution may need to be discarded and application can be restarted even after a long break, which not only has an economic benefit, but also may have an environmental benefit, as prepared solution that cannot be used immediately does not need to be discarded;

The concentrate may easily be diluted and dispersed ensuring that the actives are transferred into the working solution and used, which in turn results in rinsing and cleaning water savings, as less water is required to wash off all residue left in the spray tanks when suspension concentrates are used. This may result in a decreased impact on the environment.

The embodiments described above may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features.

Further, where specific integers are mentioned herein which have known equivalents in the art to which the embodiments relate, such known equivalents are deemed to be incorporated herein as if individually set forth. WORKING EXAMPLES

The above described liquid suspension concentrate and methods of manufacture and use are now described by reference to specific examples.

EXAMPLE 1 A general liquid suspension concentrate comprising terbuthylazine and hexazinone may comprise the following compounds and amounts as shown in Table 1 below:

Table 1 - General Dual Triazine Formulation

EXAMPLE 2

An example of a specific liquid suspension concentrate may be as shown in Table 2 below, labelled

Formulation 1:

Table 2 - Formulation 1

EXAMPLE S An example of a specific liquid suspension concentrate may be as shown in Table 3 below labelled

Formulation 2:

Table 3 - Formulation 2

EXAMPLE 4

An example of a specific liquid suspension concentrate may be as shown in Table 4 below, labelled

Formulation 3:

Table 4 - Formulation 3

EXAMPLE 5

An example of a specific liquid suspension concentrate may be as shown in Table 5 below, labelled

Formulation 4:

Table 5 - Formulation 4

EXAMPLE 6

The above examples use solvent naphtha aromatic as the water immiscible solvent. This water immiscible solvent can be easily replaced by other water immiscible solvents with similar properties to solvent naphtha aromatic. Tables 6 to 11 below illustrate other liquid suspension concentrates using different water immiscible solvents.

Table 6- Formulation 5

Table 7- Formulation 6

Table 8- Formulation 7

Table 9- Formulation 8

Table 10 - Formulation 9

Table 11 - Formulation 10

EXAMPLE 7

As described above, the inventor identified the water immiscible solvent was unexpectedly found to allow for easy re-dispersion of diluted and stored liquid suspension concentrates.

The actual mechanism of how water immiscible solvent improves storage stability is understood by the inventor to be due to the water immiscible solvent providing "slipperiness" to suspended particles preventing them from strongly binding with each other and forming larger agglomerates.

The advantage of using water immiscible solvent was confirmed by in an experiment. Three formulations being liquid suspension concentrates were prepared as follows:

Trial Formulation 1 was prepared as per Formulation 1 described in Example 2 above;

Trial Formulation 2 was prepared as per Formulation 1 described in Example 2 above however no water immiscible solvent was added to Trial Formulation 2;

Trial Formulation 3 was prepared as per Example 12 described in prior art document CN10408230A noting that Example 12 from CN10408230A represents the closest known art to the liquid suspension concentrate described herein and which, as noted, does not have water immiscible solvent present.

Working solutions of the three Trial Formulations above were prepared and mixed until complete dispersion occurred to prepare the suspension. The Trial Formulations were then put into containers and stored at ambient conditions and undisturbed for 10 hours.

After storage, precipitate caking was observed in all three Trial Formulations.

The containers in which each Trial Formulation was held were then inverted gently 10 times in an attempt to re-disperse the Trial Formulation suspensions and the results shown in Figure 1. As can be seen in Figure 1, the only caking precipitate that fully transferred back into suspension, was Trial Formulation 1 prepared as per Example 2, where water immiscible solvent was present. Trial Formulation 2 using the same formulation as Example 2 Formulation 1 without water immiscible solvent present did not re-disperse at all.

Similarly, as anticipated, prior art Trial Formulation 3 which does not have water immiscible solvent, also did not re-disperse.

The results found from Trial Formulation 2 and 3 are consistent with the prior art that leads away from mixing the described actives in suspension due to caking issues and inability to re-disperse the mixture once separation occurs.

The above example demonstrates the inventor's finding that water immiscible solvent leads to the ability to re-disperse the formulation and how the use of water immiscible solvent appears to contribute to overall physical stability of the suspension concentrate, especially at ambient temperatures.

EXAMPLE 8

In this experiment, the versatility of different water immiscible solvents is demonstrated.

Experiments were completed using other types of water immiscible solvent to demonstrate that the redispersion effect of the water immiscible solvent can be achieved using a variety of types of water immiscible solvent.

Trial Formulations 4, 5 and 6 using as water immiscible solvent:

Recosol D60™ (Trial Formulation 4 being from Table 8 Example 6 above);

Toluene (Trial Formulation 5 being from Table 7 Example 6 above);

Solvent C9™ (Trial Formulation 6 being from Table 9 Example 6 above).

The Trial Formulations were prepared, suspended and diluted with water. Storage and re-dispersion in a diluted form represents a maximally challenging case for management of caking and subsequent redispersion.

The Trial Formulations were stored at ambient conditions and undisturbed for 7 hours and then gently inverted 10 times to test for re-dispersion. As shown in Figure 2, all three Trial Formulations completely re-dispersed with no visual sign of remaining caking thus confirming the water immiscible solvent can be varied and yet achieve the same results around re-dispersion.

EXAMPLE 9 As noted above, the amount of water immiscible solvent that may be used may vary from 0.5% w/v to 10% w/v. An experiment was completed to illustrate the impact of water immiscible solvent concentration on re-dispersion of liquid suspension concentrate using the following trial formulations:

Trial Formulation 7 = Sample of Formulation 1 Example 2 with only 0.5% w/v water-immiscible solvent present;

Trial Formulation 8 = Sample of Formulation 1 Example 2 with 10% water-immiscible solvent present;

Trial Formulation 9 = Sample of Formulation 1 Example 2 where condensed methyl naphthalene sulfonate sodium salt is replaced by the same amount of a different dispersant sodium lignosulfonate.

The trial formulations were prepared, suspended and then left at ambient conditions and undisturbed for 10 hours standing time. After this time period, the samples were then inverted gently 10 times and visually evaluated for re-dispersion.

As shown in Figure 3, Trial Formulation 7 only partly re-dispersed illustrating the lower limit for water immiscible solvent concentration. Trial Formulation 8 with 10% w/v/ water immiscible solvent concentration shows complete re-dispersion.

Trial Formulation 9 gave only partial re-dispersion indicating the need for water immiscible solvent and condensed methyl naphthalene sulfonate sodium salt as a first dispersing agent to achieve fully redispersible suspension if the suspension is to be left undisturbed for prolonged periods of time (or to add more water immiscible solvent if condensed methyl naphthalene sulfonate sodium salt is not used).

As shown in Figure 4, Trial Formulation 7 using 0.5% w/v water-immiscible solvent does completely redisperse after 30 inversions hence, this lower limit of 0.5% w/v could be used albeit, the separation is less easy to re-disperse.

From a practicality and cost perspective, the inventor identified that approximately 1% w/v water immiscible solvent may be an optimum concentration to achieve full and rapid re-dispersibility of formed precipitate/caking although some variation from %\N/\I may occur.

EXAMPLE 10

As noted above, the liquid suspension concentrate described has extended stability. The stability was tested to confirm this property.

Formulation 1 described above in Example 2 was prepared and subjected to stability evaluation according to CIPAC guidelines.

The results of accelerated stability at 54°C for 14 days are presented in Table 12 below. Table 12 - Stability Trial Results

The above near identical results before and after accelerated aging confirmed the stability identified for the concentrates described herein.

EXAMPLE 11

A further stability trial was completed to confirm the accelerated aging findings.

250mL of Formulation 1 described above in Example 2 was placed in a clear PVC container and left untouched for 1 month. Observations were taken at the start of the experiment and once the experiment was complete after 1 month to evaluate the stability of the suspension when left undisturbed for prolonged periods of time.

The observations completed were to measure for physical stability based on:

• Visual observation of formed "oil" phase in the top layer of the sample and measurement of formed liquid phase;

• Changes in colour, formation of larger particles/ "flakes";

• Noticeable sedimentation of suspended active ingredients. Figure 5 shows photos of the liquid suspension concentrate at time 0 [A], after 8 days [B], after 11 days [C], after 19 days [D], after 27 days [E] and after 28 days [F].

At each time point the sample was checked for formed free "oil" layer, any visual changes in appearance (for example, formation of coarse particles/ "flakes"), formation of solid sedimentations, any visually observed phase separation indicating sedimentation or separation of suspended solids from the total volume.

As can be seen from the photographs in Figure 5, the only noticeable change during this experiment was formation of traces of "free oil" on the surface of the liquid. This free oil formation was expected as this is normal for suspension concentrates and is insignificant in practice as the free oil quickly re-disperses when the formulation is shaken. No other changes were observed with the formulation when left over time confirming the stability of the formulation.

EXAMPLE 12

The stability of a working solution produced from the suspension concentrate was further tested and compared to existing art concentrates.

The sample of Formulation 1 Example 2 was diluted to a working solution concentration (equivalent to llOmL of suspension concentrate mixed with 890mL water being the approximate knapsack application rate) using tap water and left undisturbed for 3 weeks. Similar solutions were prepared with commercially available formulations comprising the herbicides ethofumesate and metamitron each on their own i.e. not mixed together in suspension concentrate form prior to dilution.

Dilution would normally occur prior to dispersing the herbicide. Caking, precipitation or other solid formation may be undesirable as it can block spray heads or otherwise disrupt dispersion.

In the experiment conducted, the three diluted samples were inverted 5 times after 3 weeks standing to evaluate "cake" formation after prolonged storage.

The results of the trial are shown in Figure 6 which illustrates a photo of the three samples side by side post inversion. The two art diluted solutions had obvious cake formation that did not dissipate post inversion. In a commercial setting, this would result in product being discarded as it is no longer usable once in this caked state. By contrast, any caking that occurred for diluted Formulation 1 Example 2 was easily re-dispersed after inversion as shown in Figure 6. As noted, a small amount of precipitated solids were observed in Formulation 1 Example 2 after storage in this diluted form however, these solids were small and readily re-dispersed back into suspension with minimal shaking. This was unexpected since some caking would have been expected post dilution and further illustrates the stability of the described suspension concentrate. EXAMPLE 13

In this example, a method of manufacturing the suspension concentrate is described.

The manufacturing process may comprise:

Charging a mixing vessel with 90% of calculated amount of carrier (e.g. water);

Adding antifoaming agent;

Adding wetting agent first dispersing agent (e.g. methyl naphthalene sulfonate sodium salt), water immiscible solvent (naptha aromatic solvent), further dispersing agent (e.g. block copolymer dispersant), all added under constant agitation;

Adding the triazine herbicide agents hexazinone and terbuthylazine;

Mixing the formed liquid over time to ensure all solid ingredients are sufficiently wetted;

Milling the mixture into <10 micron size particles;

Adding further carrier (water), preservative and pre-dispersed solution of thickener (xanthan gum) in anti-freezing agent (monopropylene glycol) under constant agitation to the particles; Adjusting the formed suspension volume with remaining carrier (water).

Quality Control steps and packing may be completed into retail sizes post the above steps being completed.

The example compounds in brackets above may be substituted by other compounds.

The water, antifoaming agent, wetting agent, water immiscible solvent, preservative and anti-freezing agent e.g. glycol, used in the above method are in liquid form prior to manufacture of the liquid suspension concentrate.

The above method is completed under ambient conditions.

EXAMPLE 14

In this example, a method of use of the suspension concentrate is described.

The use in a practical context may be achieved by selecting a liquid suspension concentrate such as those described above and labelled as Formulation 1-10. The liquid suspension concentrate may then be applied to a plants and substrate on and about a target plant either as a concentrate or post dilution.

For example, the target plant may be Pinus radiata seedling and the liquid suspension concentrate is applied to the Pinus radiata seedlings and surrounding soil and plant matter. The aim of the application may be to allow the Pinus radiata seedlings to grow without competition form surround weeds or other plant matter and hence allowing the seedlings to establish preferentially over the surround plants. Mention is made here of Pinus radiata being a target plant for preferential growth. It is envisaged that the liquid suspension concentrate may be used to target preferential growth of many types of plant, examples comprising: forestry plants, cereal crops, orchard crops, nitrogen fixing crops, and combinations thereof. The liquid suspension concentrate application rate used may be the same as that used for each individual active agent alone. Application may be by spraying post seedling planting and the ratio of active agents used varied to suit the target plant, the season / growth stage of surrounding vegetation, or to suit other factors.

Spraying is noted and may be to foliar growth of the surrounding plants to be slowed or killed. Non- foliar application may also assist to slow or kill growth for example to target seeds or root systems.

Aspects of the liquid suspension concentrate and methods of manufacture have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the claims herein.

Claims

1. A liquid suspension concentrate configured to be sufficiently stable to support at least 2 years shelf life comprising:

2. The liquid suspension concentrate as claimed in claim 1 wherein the liquid suspension concentrate comprises l-20%w/v hexazinone and 10-50%w/v terbuthylazine.

3. The liquid suspension as claimed in claim 1 wherein the water immiscible solvent is an organic solvent with a viscosity below 10mm²/s @25°C.

4. The liquid suspension concentrate as claimed in claim 1 wherein the water immiscible solvent is selected from: naptha aromatic solvent, kerosene, white spirits, turpentine, isopropyl myristate, isophorone, toluene, other aromatic hydrocarbon compounds, and combinations thereof.

5. The liquid suspension concentrate as claimed in claim 1 wherein the water immiscible solvent comprises 0.5%w/v to 10%w/v of the liquid suspension concentrate.

6. The liquid suspension concentrate as claimed in claim 1 wherein the liquid suspension concentrate comprises a first dispersing agent and wherein the first dispersing agent is a polymeric anionic dispersing agent.

7. The liquid suspension concentrate as claimed in claim 6 wherein the polymeric anionic dispersing agent is condensed methyl naphthalene sulfonate sodium salt.

8. The liquid suspension concentrate as claimed in claim 6 wherein the first dispersing agent comprises 0.5-20%w/v of the liquid suspension concentrate.

9. The liquid suspension concentrate as claimed in claim 1 wherein the liquid suspension concentrate comprises a wetting agent and wherein the wetting agent is an ethoxylated alcohol.

10. The liquid suspension concentrate as claimed in claim 9 wherein a concentration of wetting agent is from 0.25-10%w/v of the liquid suspension concentrate.

11. The liquid suspension concentrate as claimed in claim 1 wherein the liquid suspension concentrate comprises a further dispersing agent, the further dispersing agent being a block copolymer dispersant.

12. The liquid suspension concentrate as claimed in claim 11 wherein the block copolymer dispersant is selected from: acrylic polymer amine salt; hydrophobically modified acrylic copolymer; polyacrylic acid and partly neutralised sodium salt; and combinations thereof.

13. The liquid suspension concentrate as claimed in claim 11 wherein a concentration of further dispersing agent is from 0.25-7%w/v of the liquid suspension concentrate.

14. The liquid suspension concentrate as claimed in claim 1 wherein the liquid suspension concentrate comprises: anti-freezing agent, antifoaming agent, thickener, preservative, carrier, and combinations thereof.

15. The liquid suspension concentrate as claimed in claim 1 wherein the liquid suspension concentrate comprises a carrier and wherein the carrier is water.

16. The liquid suspension concentrate as claimed in claim 1 wherein the liquid suspension concentrate has a viscosity of 700-75, OOOmPa.s when measured with Brookfield viscometer, Spindle 3.

17. The liquid suspension concentrate as claimed in claim 1 wherein the liquid suspension concentrate is an aqueous suspension.

18. A liquid suspension concentrate configured to be sufficiently stable to support at least 2 years shelf life comprising: terbuthylazine; hexazinone; water immiscible solvent; a first dispersing agent comprising condensed methyl naphthalene sulfonate sodium salt; wetting agent; and a further dispersing agent comprising block copolymer dispersant.

19. The liquid suspension concentrate as claimed in claim 18 further comprising: anti-freezing agent, antifoaming agent, thickener, preservative, carrier, and combinations thereof.

20. A liquid suspension concentrate configured to be sufficiently stable to support at least 2 years shelf life comprising: terbuthylazine 97% purity; hexazinone 98% purity; water immiscible solvent; condensed methyl naphthalene sulfonate sodium salt; ethoxylated alcohol; block copolymer dispersant; monopropylene glycol; xanthan gum; preservative; antifoaming agent; and water.

21. The liquid suspension concentrate as claimed in claim 18 comprising:

35-50%w/v terbuthylazine 97% purity;

5.0-15%w/v hexazinone 98% purity;

0.5-10%w/v water immiscible solvent;

1.5- 3.5% w/v condensed methyl naphthalene sulfonate sodium salt;

1.5-3.0%w/v ethoxylated alcohol;

1.0-3.5%w/v block copolymer dispersant;

5-10%w/v monopropylene glycol;

0.15-0.25%w/v xanthan gum;

0.05-0. l%w/v preservative ;

0.1-1.0%w/v antifoaming agent; and to 100% water.

22. A diluted liquid suspension configured to be sufficiently stable to support at least 2 years shelf life comprising: a liquid suspension concentrate comprising: terbuthylazine, hexazinone, water immiscible solvent, first dispersing agent, wetting agent, further dispersing agent; and aqueous carrier; wherein aqueous carrier is added at a ratio of 1 part liquid suspension concentrate to 1 to 100 parts aqueous carrier.

23. The diluted liquid suspension as claimed in claim 20 wherein the diluted liquid suspension does not form a hard to disperse cake for at least 3 weeks post dilution with water.

24. A method of manufacturing a liquid suspension concentrate comprising hexazinone and terbuthylazine configured to be sufficiently stable to support at least 2 years shelf life by: mixing together carrier, water immiscible solvent, first dispersing agent, wetting agent, further dispersing agent; adding hexazinone and terbuthylazine; mixing until all solid ingredients are wetted to produce a formed liquid; milling the formed liquid to produce formed particles; adding further carrier to the formed particles under constant agitation to form a liquid suspension concentrate.

25. The method as claimed in claim 24 wherein antifoaming agent is added to the carrier, water immiscible solvent, first dispersing agent, wetting agent, further dispersing agent.

26. The method as claimed in claim 24 wherein preservative, thickener and anti-freezing agent are added with the further carrier to the formed particles.

27. A method of use comprising: selecting a liquid suspension concentrate as claimed in claim 1; applying the liquid suspension concentrate to an area to be treated; wherein the area to be treated comprises: a target plant, the target plant being substantially unaffected by the liquid suspension concentrate; and a plant or part thereof affected by the active compounds in the liquid suspension concentrate in a way that slows or kills growth of the plant or part thereof.