AU2014201871C1 - Herbicidal granule composition and method - Google Patents

Abstract

The invention relates to a hexazinone granule composition and a method of preparation and use of the composition.

Description

Granular Products Assets Pty Ltd (72) Inventor(s)

Pentland, Philip Edward;Le, Tung Ngoc;Flynn, Anthony Gerard (74) Agent / Attorney

Phillips Ormonde Fitzpatrick, L 16 333 Collins St, Melbourne, VIC, 3000, AU (56) Related Art

WO 2010/000365 A2

Material Safety Data Sheet, Hexazinone 240 SL, Arysta Lifescience South Africa, 2005 [online], [retrieved from internet on 21 July 2017] <URL: http:// www.icaterpillar.com.cn/wps/cpxxfile/xgfj/20151112231515482.pdf >

CN 201627759 A

WO 2009/054823 A2 WO 2009/064702 A2 US 5443764 A

2014201871 01 Apr 2014

ABSTRACT

The invention relates to a hexazinone granule composition and a method of preparation and use of the composition.

2014201871 01 Apr 2014

Herbicidal Granule Composition and Method

Field

This invention relates to granules comprising the herbicide hexazinone for use in aerial and broadcast application and to a method of preparation of the herbicidal granules and their use in control of weeds by aerial broadcasting.

Background

Hexazinone is a triazine herbicide with action against perennial weeds and woody weeds. For example in Australia Brigalow (Acacia Harpophylla) and Prickley Acacia (Acacia Nilotica) are endemic woody weeds susceptible to Hexazinone. It is readily absorbed in the root zone and translocated through the weed plant. Hexazinone has been formulated as a 25% solution in ethanol which is sold commercially under the trade name Velpar by Dupont.

Hexazinone has also been formulated as a granule. For example, Proserve Incorporated of Memphis Tennessee USA have formulated hexazinone as a 10% granule which is sold under the trade name Pronone 10G for the control of woody weeds. Rainfall dissolves the hexazinone from the granules and moves it to the root zone where it is absorbed during active periods of plant growth.

US 4979979 (McCollum et al. filed 1989, assigned to DuPont) describes a granular herbicidal composition with characteristics that permit application effectively to forests and woodlands aerially and with minimum drift. The main claim teaches a herbicidal granular particulate composition comprising 50 - 99% by weight hexazinone wherein at least 95% of the granular particulates by weight have drop times (as defined in the text) of from 2-35 seconds and attrition of less than 2% by weight particles having a drop time greater than 35 seconds, said composition having a release rate in water of 55-95% by weight of the herbicide in 4 minutes. In the example 1 of US 4979979 the granulation method is described as follows: 98% hexazinone technical, lactose monohydrate, diisopropylnaphthalene sulfonate sodium salt, polyethoxylated dinonylphenol, sodium 1

2014201871 01 Apr 2014 stearate and sodium alginate are blended in a ribbon blender for 15 minutes, then fed to a no 2 DH hammermill without a screen for de-lumping and then re-blended in another ribbon blender. This blend is then fed to a 24 in diameter air mill to yield a premix of average particle size 17 microns. Pan granulation is used to form damp granules, which 5 are then partially dried in a fluidised vibrating-bed dryer, then fully dried through a similar dryer and then sieved through a stack of vibrating screens to give a final semi-spherical product.

The teachings of US 4979979 show that complex and energy-consuming production 10 methods are required to provide a pan-granulated semi-spherical product. For example, significant energy is expended in grinding the components, and in both of the drying steps.

Feng et al. in Journal of Environmental Science and Health B23(3): 267 - 278 (1988) 15 describe the manufacture and mode of action of the hexazinone granule Pronone 10G in the following terms: The granules are built up from a hard insoluble clay-based material.

This material is surface-coated with 10%w/w hexazinone solid, and these intermediatestage granules are protected by an outer coating free from hexazinone. The hexazinone is released to the forest floor by the first available moisture (rain and dew). The higher concentration of herbicide in a column form may facilitate root uptake compared to the broadcast application of a liquid formulation at the same rate.

Dupont have made and sold water-dispersible granular formulations of hexazinone, and this type of water-dispersible granule has also been described in US 5443764.

The discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of this application.

2014201871 17 Jan 2018

There is a need for improved methods of making granular formulations of hexazinone for aerial or broadcast application, and in particular there is a need to achieve (a) a low-energy process which avoids the steps of fine grinding and drying; and (b) a simple process that does not involve a separate coating operation and which comprises a small number of process steps.

There is a further need for a granule production process that can be carried out in simple, inexpensive and readily-available manufacturing equipment.

Summary

There is provided a method for making hexazinone granules, comprising the steps of: forming a solution comprising:

(a) hexazinone in an amount of at least 40% w/w (preferably at least 50 % w/w) of the solution; and (b) a hydrophilic tackifying agent agent in an amount of at least 1% w/w of the solution;

in a liquid carrier wherein the liquid carrier comprises water miscible organic solvent in an amount of at least 40% w/w (preferably at least 50 % w/w) of the liquid carrier; (preferably in a weight ratio of one part solution to at least 4 parts granular carrier material of size 0.5mm to 5mm to absorb the solution into the granular carrier material), and agitating the mixture until the granules flow and separate.

The hexazinone is preferably solubilised in the liquid carrier by heating the composition to a temperature of at least 40°C, preferably at least 50°C and more preferably at least 60°C. The heaxazinone solution upon absorption in to the granule composition is cooled and is adapted to provide a crystalline deposit in the granular carrier at a temperature of 20°C.

In a further aspect there is provided a hexazinone granule composition comprising:

(a) hexazinone in an amount of from 5 to 20 % w/w of the granular herbicide;

(b) liquid carrier comprising at least 50 % w/w water miscible organic compound;

(c) hydrophilic tackifying agent agent in an amount of from 0.01% to 5% w/w of the granular herbicide; and

2014201871 17 Jan 2018 (d) a granular carrier;

wherein the hexazinone is present in the granular carrier in the form of solid, preferably crystalline, particles.

The liquid carrier is absorbed directly into particulate granular carrier without the need for agglomeration to form the granules. The solid carrier is thus preferably not agglomerated by agglomeration granulation as is common in the industry but is absorbed onto primary particles of granular solid carrier as distinct from particles which are an agglomeration of secondary particles which are a powder of size much less than the primary granule particle.

The composition may be prepared in a rotating drum type mixer in which the granules are mixed with the liquid carrier to absorb the liquid into the solid granular carrier until the herbicidal granules are of free flowing consistency.

There is further provided in one set of embodiments a method of controlling perennial woody weeds (such as Brigalow (Acacia Harpophylla) and Prickley Acacia (Acacia Nilotica)) in an area of land comprising broadcasting onto the land the herein described hexazinone granules.

Throughout the description and the claims of this specification the word “comprise” and variations of the word, such as “comprising” and “comprises” is not intended to exclude other additives, components, integers or steps.

Detailed Description

A liquid carrier is used to apply the hexazinone, hydrophilic tackifying agent as a solution in the liquid carrier.

The liquid carrier comprises at least 40% w/w (preferably at least 50% w/w) of water miscible organic solvent.

2014201871 01 Apr 2014

Examples of the water miscible organic solvent suitable for providing at least 40% w/w hexazinone(preferably at least 50% w/w and more preferably at least 60% w/w hexazinone) include alkylene carbonates, glycerol formal and Ci to Cq alkyl mono ethers of at least one of ethylene glycol, diethylene glycol and triethylene glycol (such as where 5 the alkyl is selected from methyl, ethyl, propyl and butyl and most preferably butyl).

Examples of more preferred water miscible organic solvents may be selected from the group consisting of diethylene glycol monobutyl ether, ethylene glycol monbutyl ether, dipropylene glycol monomethyl ether, 1, 2- propanediol, propane-1,2,3-triol, N-methyl-210 pyrrolidone, triethylene glycol, diethylene glycol monoethyl ether, high and low polarity alkylene carbonates and their mixtures, polyethylene glycol of molecular weight from 200 to 800 (preferably 200 to 600), glycerol formal, 2-ethylhexanol and isopropanol.

In one set of embodiments the water miscible organic solvent comprises at least one of glycerol formal and C2 to C4 alkylene carbonate. Ethylene carbonate and propylene carbonate are generally more preferred.

In one set of embodiments the solvent selected from the group consisting of C₂ to C₄ alkylene carbonates and glycerol formal constitutes at least 40 % w/w (preferably 50 % w/w and more preferably at least 60 % w/w) of the liquid carrier. The combined amount of these solvents is generally no more than 90 % w/w (preferably no more than 85% w/w and still more preferably no more than 80 % w/w) of the total liquid carrier. The liquid carrier may, and preferably will, comprise water. The amount of water in the liquid carrier is preferably at least 10 % w/w and preferably at least 15 % w/w and more preferably at least 20 % w/w of the liquid carrier.

The hexazinone will preferably be soluble in the carrier liquid at a temperature of no more than 80°C and preferably no more than 70°C. Most preferably the hexazinone is soluble in the carrier liquid at 60°C. In a particularly preferred embodiment the hexazinone is not fully soluble. It is preferred that at least 25% of the hexazinone is insoluble in the carrier at 0^QC. More preferably at least 25% by weight of the hexazinone

2014201871 01 Apr 2014 is insoluble in the liquid carrier at 20^QC. The type of organic solvent used in the liquid carrier and the proportion of water may be balanced without undue experimentation to provide these desired solubility parameters.

A tackifying agent is present in a hexazinone granule composition in an amount ranging from 0.01% to 5% w/w of the hexazinone granule composition. In a further embodiment, the tackifier component is present in an amount ranging from 0.05 % to 2% by weight of the hexazinone granule composition. We have found that there is a strong tendency for crystalline hexanone to dislodge as fine particles from the carrier granule and the 10 tackifier reduces significantly this problem by retaining the crystalline hexazinone within the granule.

The tackifying agent may be carbohydrate, protein, lipid, synthetic polymer, glycolipid, glycoprotein, lipoprotein, lignin, a lignin derivative, a carbohydrate-based composition, and a combination thereof. In one embodiment the tackifier component is a lignin derivative and is optionally calcium lignosulfonate. Alternatively, the tackifier component is selected from the group consisting of: a monosaccharide, a disaccharide, an oligosaccharide, a polysaccharide and combinations thereof. Specific carbohydrate tackifiers illustratively include glucose, mannose, fructose, galactose, sucrose, lactose, maltose, xylose, arabinose, trehalose and mixtures thereof such as corn syrup; celluloses such as carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxy-methylethylcellulose, hydroxyethylpropylcellulose, methylhydroxyethyl-cellulose, methylcellulose; starches such as amylose, seagel, starch acetates, starch hydroxyethyl ethers, ionic starches, long-chain alkyl starches, dextrins, amine starches, phosphates starches, and dialdehyde starches; plant starches such as corn starch and potato starch; other carbohydrates such as pectin, amylopectin, xylan, glycogen, agar, alginic acid, phycocolloids, chitin, gum arabic, guar gum, gum karaya, gum tragacanth and locust bean gum; vegetable oils such as corn, soybean, peanut, canola, olive and cotton seed; complex organic substances such as lignin and nitrolignin; derivatives of lignin such as lignosulfonate salts illustratively including calcium lignosulfonate and sodium lignosulfonate and complex carbohydrate-based compositions containing organic and

2014201871 01 Apr 2014 inorganic ingredients such as molasses. Suitable protein tackifiers illustratively include soy extract, zein, protamine, collagen, and casein. Tackifiers operative herein also include synthetic organic polymers capable of promoting or producing cohesion of particle components and such tackifiers illustratively include ethylene oxide polymers, 5 polyacrylamides, polyacrylates, polyvinyl pyrrolidone, polyethylene glycol, polyvinyl alcohol, polyvinylmethyl ether, polyvinyl acrylates, polylactic acid, and latex. In a preferred embodiment, the tackifier comprises a cellulose such as carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxymethylethylcellulose, hydroxyethylpropylcellulose, methylhydroxyethyl-cellulose, 10 methylcellulose and mixtures of two or more thereof.

In a preferred set of embodiments the tackifying agent comprises at least one selected from the group consisting of celluloses such as carboxymethylcellulose; ethylcellulose; hydroxyethylcellulose; hydroxymethylethylcellulose; hydroxypropylmethylcellulose;

hydroxypropyl; partially hydrolysed polyvinyl alcohol; styrene acrylate polymers; acrylic ester styrene polymers; polyvinyl pyrrolidine; and galactomannan gums such as guar and hydroxyl propyl guar.

The more preferred tackifying agents are hydroxypropylmethylcellulose and acrylic ester polymers and methacrylic ester polymers such as C1-C4 alkyl acrylate polymers and Ci C₄ alkyl methacylate polmyers.

Examples of granular carriers useful for formulating the hexazinone granules include clay, bentonite including sodium and calcium bentonite, talc, calcium carbonate, sodium carbonate, zeeklite, sericite, acid clay, quartzite, diatomaceous silica, pumice, zeolite, vermiculite, potassium chloride, urea, white carbon, ammonium sulfate, sodium sulfate, perlite, magnesium sulfate, kaolin, attapulgite and the like. The more preferred carriers are generally attapulgite and kaolin including sodium kaoline and potassium kaolin and mixtures thereof.

2014201871 17 Jan 2018

The granular carrier is of particle size in the range of from 0.5 mm to 4 mm formed by milling material of larger size and sieving to provide carrier granules of size in the range of from 0.5 mm to 4 mm.

The solid carrier may constitute up to 95% by weight of the composition but will typically be up to 90% by weight of the hexazinone granule composition. The solid carrier will generally be at least 65% w/w of the hexazinone granule composition such as at least 70 % w/w or at least 75 % w/w of the herbicidal granule composition.

In one set of embodiments the hexazinone granule composition comprises:

(a) hexazinone in an amount of from 5 to 20 % w/w of the hexazinone granule composition;

(b) liquid carrier comprising at least 40% w/w, preferably 50% w/w to 90 % w/w (more preferably 60 % w/w to 80 % w/w) water miscible organic compound preferably selected from the group consisting of C₂ to C₄ alkylene carbonates and glycerol formal and from 10 w/w % to 50 % w/w water; and (c) hydrophilic tackifying agent agent in an amount of from 0.01% to 5% w/w preferably 0.05 %w/w to 2 % w/w of the granular herbicide; and (d) a granular carrier, preferably selected from attapulgite and bentonite and mixtures thereof, of particle size (preferably unagglomerated particles) in an amount of from 65 % w/w to 95 % w/w of the total hexazinone granule composition; wherein the hexazinone is present in the granular carrier in the form of solid, preferably crystalline, particles.

In one set of embodiments the hexazinone solution which is absorbed on the granular carrier comprises from 20% to 65% w/w hexazinone from 20% to 55% w/w water miscible organic compound;

from 0% to 20% w/w water; and from 1 % to 6% w/w tackifying agent

2014201871 01 Apr 2014 wherein the amounts are by weight of the hexazinone solution absorbed in the granular carrier.

In a more preferred set of embodiments the hexazinone solution which is absorbed into the granular carrier comprises:

from 50% to 60% w/w hexazinone;

from 35% to 50% w/w water miscible organic liquid;

from 8% to 20% w/w water; and from 1.5% to 4% w/w water tackifying agent.

wherein the amounts are by weight of the hexazinone solution absorbed in the granular carrier.

The liquid carrier is preferably absorbed directly into particulate granular carrier without the need for agglomeration. The solid carrier is thus preferably not agglomerated by agglomeration granulation as is common in the industry but is absorbed onto primary particles of granular solid carrier as distinct from particles which are an agglomeration of secondary particles which are a powder of size much less than the primary granule particle.

The final hexazinone granule composition, in one set of embodiments comprises granules, of particle size of at least 0.5 mm and more preferably at least 1 mm. Generally the granular carrier has a particle size of no more than 5 mm and more preferably no more than 4 mm. The granules are thus typically of particle size in the range of from 0.5 mm to 5 mm, more preferably 0.5 mm to 4 mm and most preferably from 1 mm to 4 mm.

The composition may be prepared in a rotating drum type mixer in which the granules are mixed with the liquid carrier to absorb the liquid into the solid granular carrier until the herbicidal granules are of free flowing consistency. For example in one set of embodiments the hexazinone granule composition is prepared in a mixer of the type

2014201871 17 Jan 2018 used in preparing concrete. The mixer may be of significant capacity such as more than 1 cubic metre or in the range of from 3m³ to 9m³ capacity.

There is further provided in one set of embodiments a method of controlling perennial woody weeds (such as Brigalow (Acacia Harpophylla) and Prickley Acacia (Acacia Nilotica)) in an area of land comprising broadcasting onto the land the herein described hexazinone granules. In one embodiment the granules are applied in an area of commercial forrest, alfalfa crop or sugarcane. The granules may be broadcast by hand by mobile applicator or by aerial broadcasting using an aircraft such as a fixed wing aircraft or helicopter which may be fitted with suitable granule broadcasting equipment. The hexazinone is released from the granules on application of water such as from rain, irrigation or the like.

The invention will now be described with reference to the following examples. It is to be understood that the examples are provided by way of illustration of the invention and that they are in no way limiting to the scope of the invention.

EXAMPLES

Examples 1 to 4

Hexazinone granular compositions of Examples 1 to 4 in accordance with the invention were prepared by the procedure below and having the compositions of Tables 1 to 4.

1. To prepare the Hexazinone concentrate, fill a mixing vessel with the required amount of the organic solvent portion of the liquid carrier (NB: It is important not to contaminate the organic solvent drum (particularly in the case of propylene carbonate) with water as this causes deterioration of product).

2. Add Hexazinone and tackifying agent to the mixing vessel and mix until uniform.

3. Add water to mixing vessel and mix until uniform (it is preferable to add water last so that the tackifying agent does not form lumps).

2014201871 01 Apr 2014

4. Heat the mixture to approximately 65^QC to dissolve Hexazinone and tackifying agent. A clear solution should result (it is preferred not to overheat as this will evaporate the solvents and/or lead to some degradation of the active).

5. Pour mixture into bentonite granular carrier of particle size in the range of from

1mm to 4mm contained in a concrete mixer while the mixer is rotating. The liquid mixture will coat the granules evenly without the need for spraying. Granules will appear very wet and sticky. The mixing is continued until granules flow and separate.

6. Granules will change to a white colour on drying/mixing.

7. Pour granules on to trays to cool and dry further if required.

Table 1 Example 1- Formulation Components as follows:

Constituent name	CAS number	Concentration	Purpose in formulation
(a) Active constituent/s
Hexazinone (98%)	51235-04-2	102 g/kg	Active ingredient
(b) Other constituents
Rutocel 60RT6- Hydroxypropyl Methyl Cellulose	9004-65-3	5.9 g/kg	Tackifying agent
Jeffsol® Propylene CarbonatePropylene Carbonate	108-32-7	52.1 g/kg	Organic solvent portion of liquid carrier
Water	7732-18-5	23.3 g/kg	Liquid carrier component
Arumpo® Bentonite kiln dried	1318-93-0	816.7 g/kg	Solid carrier

2014201871 01 Apr 2014

Table 2 Example 2- Formulation Components as follows:

Constituent name	CAS number	Concentration	Purpose in formulation
(a) Active constituent/s
Hexazinone (98%)	51235-04-2	102 g/kg	Active ingredient
(b) Other constituents
Acronal ECO A530ap polymer based on acrylic ester, methacylic ester		5.9 g/kg	Tackifying agent
Jeffsol® Propylene CarbonatePropylene Carbonate	108-32-7	52.1 g/kg	Organic solvent portion of liquid carrier
Water	7732-18-5	23.3 g/kg	Liquid carrier component
Arumpo® Bentonite kiln dried	1318-93-0	816.7 g/kg	Solid carrier

Table 3 Example 3- Formulation Components as follows:

Table 1 Example 1Formulation Components as follows: Constituent name	CAS number	Concentration	Purpose in formulation
(a) Active constituent/s
Hexazinone (98%)	51235-04-2	102 g/kg	Active ingredient
(b) Other constituents
Rutocel 60RT6- Hydroxypropyl Methyl Cellulose	9004-65-3	5.9 g/kg	Tackifying agent
Glycerol formal	4740-78-7 5464-28-8	52.1 g/kg	Organic solvent portion of liquid carrier
Water	7732-18-5	23.3 g/kg	Liquid carrier component
Arumpo® Bentonite kiln dried	1318-93-0	816.7 g/kg	Solid carrier

2014201871 01 Apr 2014

Table 4 Example 4- Formulation Components as follows:

Constituent name	CAS number	Concentration	Purpose in formulation
(a) Active constituent/s
Hexazinone (98%)	51235-04-2	102 g/kg	Active ingredient
(b) Other constituents
Acronal ECO A530ap polymer based on acrylic ester, methacylee ester		5.9 g/kg	Tackifying agent
Glycerol formal	4740-78-7 5464-28-8	52.1 g/kg	Organic solvent portion of liquid carrier
Water	7732-18-5	23.3 g/kg	Liquid carrier component
Arumpo® Bentonite kiln dried	1318-93-0	816.7 g/kg	Solid carrier

Details of organic solvants and tackifying agents which may be used and there chemical id trade names are provided in Tables 5 and 6 respectively.

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2014201871 01 Apr 2014

Example 5

The process of Example 1 may be repeated using a liquid carrier comprising the following combinations of organic solvent (“solvent 1”) and water (“solvent 2”).

Solvent 1	Solvent 2	Total % w/w solvent in granule	% Hexazinone (w/w) in solvent blend	Ratio (solvent 1: solvent 2)	Results
JEFFSOL® AG1555	Water	7.5	57.1	69.3 : 30.7	Dissolves @ 60-C
JEFFSOL® AG- 1505	Water	7.5	57.1	69.3 : 30.7	Does not dissolve
JEFFSOL® AG1530	Water	7.5	57.1	69.3 : 30.7	Dissolves @ 60-C
JEFFSOL® AG1540	Water	7.5	57.1	69.3 : 30.7	Dissolves @ 60-C
Propylene carbonate	Water	7.5	56.3	69.1 : 30.9	Dissolves @ 60-C

Liquid concentrate and binding agent (Rutocel 60RT6 is a HPMC)

Liquid concentrate contains Hexazinone 56.6%wt, Rutocel 3.3%wt, Jeffsol PC 28.9%wt, Water 11,2%wt

Granules prepared without a tackifying agent such as Rutocel (HPMC) are dusty.

Re-crystallized Hexazinone crystals flake off once the granule has completely dried.

Increased concentration of Rutocel increases drying time, increases viscosity of liquid concentrate and decreases uniformity of application.

Rutocel tested at concentrations of 5.6-11.7 g/kg of granule. 5.9 g/kg was found to have the optimal drying time.

Liquid concentrate with added 10 g/kg of propylene glycol increases drying time.

Liquid concentrate does not dissolve if water is substituted with propylene glycol. Even at 60^QC

Concentration of water must be kept low to not cause disintegration of the granule, but sufficient to dissolve the Rutocel.

2014201871 01 Apr 2014

Example 6

Table 7a and 7b shows the preparation of solutions of hexazinone in various organic solvents which may be used alone in combination with each other, where miscible or with addition of water to provide a solution of hexazinone at elevated temperature of 60^QC but in which hexazinone, is at least partly insoluble at 25^Q.

2014201871 01 Apr 2014

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2014201871 01 Apr 2014

Example 7

The granules described in Example 1 Table 1 (100 g hexazinone per kg of granules) were used in the following bioefficacy trial.

Trials were carried out on four 10mx10m plots for each rate of granule application shown in Table 8 at Shauna Hills Bauhinia, Central Queensland Australia. The plots were infested with brigalow tree weeds. Application of granules (g/100m²) was carried out in early May using a “Scotts Easy” Hand-Held Spreader (2m swath +/- 0.5m). Product was weighed using OHAUS Precision Plus Scales.

Ten months after application of the granules, the plots were inspected and brigelow trees in the treated areas were visually categorised as dead, stressed or healthy.

The results are shown in Table 8.

Table 8

Application rate (weight of granules 2 - g per 100m )	Starting tree count (brigelow) Total over 4 plots	Dead trees	Stressed trees	Healthy trees
Zero	15	-	2	11
200	40	2	29	5
400	33	24	11	1
600	45	36	6	1

Note that 200g granules per 100m² plot corresponds to 20g hexazinone active agent per 20 100 m² plot, which in turn corresponds to 2 kg hexazinone active agent per hectare.

2014201871 17 Jan 2018

Claims (30)

1. Claims

   1. A method for making hexazinone granules, comprising the steps of:

   forming a solution comprising (a) hexazinone in an amount of at least 40% w/w of the solution and (b) a hydrophilic tackifying agent, in a liquid carrier wherein the liquid carrier comprises water miscible organic solvent in an amount of at least 40% w/w of the liquid carrier; and mixing solution with a granular carrier material of size 0.5mm to 5mm to absorb the solution into the granular carrier material, and agitating the mixture until the granules flow and separate.
2. 2. A method according to claim 1 wherein the tackifying agent is present in an amount of at least 1% w/w of the solution and mixing of the solution with a granular carrier material is carried out in a weight ratio of one part of the solution to at least four parts of the granular carrier material.
3. 3. A method according to claim 1 wherein the hexazinone is in an amount of at least 50% w/w of the solution.
4. 4. A method according to any one of claims 1 to 3 comprising dissolving the hexazinone in the liquid carrier by heating the composition to a temperature of at least 40°C, absorbing the solution into the granular carrier material and cooling the composition to form solid particles of hexazinone in the granular carrier.
5. 5. A method according to any one of claims 1 to 4 wherein the hexazinone is soluble in the carrier liquid at 60°C and at least partly insoluble at a temperature of 20°C.
6. 6. A method according to any one of claims 1 to 5 the water miscible organic solvent is selected from the group consisting of (C2 to C₄ alkylene) carbonates, glycerol formal and mixtures of two or more thereof.

   2014201871 17 Jan 2018
7. 7. A method according to any one of claims 1 to 6 wherein the water miscible organic solvent is selected from the group consisting of ethylene carbonate, propylene carbonate and mixtures thereof.
8. 8. A method according to any one of claims 1 to 7 wherein the combined amount of (C2 to C4 alkylene) carbonates and glycerol formal is in the range of from 60 % w/w to 85 % w/w of the liquid carrier.
9. 9. A method according to any one of claims 1 to 8 wherein the liquid carrier comprises water in an amount in the range of from 10% w/w to 40% w/w of the liquid carrier composition.
10. 10. A method according to any one of claims 1 to 9 wherein the hexazinone solution comprises

    20% to 65% w/w hexazinone;

    20% to 55% w/w water miscible organic solvent; comprised 0% to 20% w/w water; and 1 % to 6% w/w tackifying agent.
11. 11. A method according to any one of claims 1 to 10 wherein the hexazinone solution comprises

    50% to 60% w/w hexazinone;

    35% to 50% w/w water miscible organic solvent;

    8% to 20% w/w water; and

    1.5% to 4% w/w tackifying agent.
12. 12. A method according to any one of claims 1 to 11 wherein the hexazinone granule composition comprises:

    (a) hexazinone in an amount of from 5 to 20 % w/w of the granular herbicide;

    (b) liquid carrier comprising at least 50% w/w water miscible organic compound; and (c) tackifying agent in an amount of from 0.01% to 5% w/w of the granular herbicide; and

    2014201871 17 Jan 2018 (d) a granular carrier;

    wherein the hexazinone is present in the granular carrier in the form of solid, preferably crystalline, particles.
13. 13. A method according to any one of claims 1 to 12 wherein a tackifying agent is present in a hexazinone granule composition in an amount ranging from 0.01% to 5% w/w of the hexazinone granule composition and a cellulose selected from the group consisting of carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxymethylethylcellulose, hydroxyethylpropylcellulose, methylhydroxyethyl-cellulose, methylcellulose and mixtures of two or more thereof.
14. 14. A method according to any one of claims 1 to 13 wherein the solid carrier comprises from 65% w/w to 95% by weight of the hexazinone granule composition.
15. 15. A method according to any one of claims 1 to 14 wherein the granular carrier is not agglomerated.
16. 16. A method according to any one of claims 1 to 15 wherein the granular carrier is of particle size in the range of from 0.5 mm to 4 mm formed by milling material of larger size and sieving to provide granules of size in the range of from 0.5 mm to 4 mm.
17. 17. A method according to any one of claims 1 to 16 wherein the solution is applied at a temperature of at least 40°C preferably at least 50°C to the granular carrier contained in a rotatable drum, the drum is rotated to distribute the solution into the granular carrier and the solution is allowed to cool to form a crystalline deposit of heaxazinone in the granular carrier.
18. 18. A method of controlling perennial woody weeds comprising at least one of Brigalow (Acacia Harpophylla) and Prickley Acacia (Acacia Nilotica) in an area of land comprising broadcasting onto the land the herein described hexazinone granules, prepared according to any one of claims 1 to 17.
19. 19. A hexazinone granule composition comprising:

    2014201871 17 Jan 2018 (a) hexazinone in an amount of from 5 to 20 % w/w of the granular herbicide;

    (b) liquid carrier for the hexazinone comprising at least 40%w/w water miscible organic compound; and (c) tackifying agent agent in an amount of from 0.01% to 5% w/w of the granular herbicide; and (d) a granular carrier of particle size 0.5mm to 5mm;

    wherein the liquid carrier and hexazinone are absorbed into the granular carrier and hexazinone is present in the granular carrier in the form of solid particles.
20. 20. A hexazinone granule composition according to claim 19 to wherein the heaxazinone is soluble in the carrier liquid at 60°C and soluble in an amount of less than 10% w/w in the liquid carrier at a temperature of 20°C.
21. 21. A hexazinone granule composition according to claim 19 or claim 20 wherein the water miscible organic solvent is selected from the group consisting of (C₂ to C₄ alkylene) carbonates, glycerol formal and mixtures of two or more thereof.
22. 22. A hexazinone granule composition according to any one of claims 19 to 21 wherein the water miscible organic solvent is selected from the group consisting of ethylene carbonate, propylene carbonate and mixtures thereof.
23. 23. A hexazinone granule composition according to any one of claims 19 to 22 wherein the combined amount of (C₂ to C₄ alkylene) carbonates and glycerol formal is in the range of from 60 % w/w to 85 % w/w of the liquid carrier for hexazinone.
24. 24. A hexazinone granule composition according to any one claims 19 to 23 wherein the liquid carrier comprises water in an amount in the range of from 10 % w/w to 60 % w/w of the liquid carrier for hexazinone.
25. 25. A hexazinone granule composition according to any one of claims 19 to 24 wherein the tackifying agent is present in the hexazinone granule composition in an amount ranging from 0.01% to 5% w/w of the hexazinone granule composition and is a cellulose selected from the group consisting of carboxymethylcellulose,

    2014201871 17 Jan 2018 ethylcellulose, hydroxyethylcellulose, hydroxy-methylethylcellulose, hydroxyethylpropylcellulose, methylhydroxyethyl-cellulose, methylcellulose and mixtures of two or more thereof.
26. 26. A hexazinone granule composition according to any one of claims 19 to 25 wherein the solid carrier comprises from 65% w/w to 95% by weight of the hexazinone granule composition.
27. 27. A hexazinone granule composition according to any one claims 19 to 26 wherein the carrier granule is selected from attapulgite, bentonite, kaolin and mixtures thereof.
28. 28. A hexazinone granule composition according to any one of claims 19 to 27 wherein the granular carrier is not agglomerated.
29. 29. A hexazinone granule composition according to any one of claims 19 to 28 wherein the granular carrier is of particle size in the range of from 0.5 mm to 4 mm formed by milling material of larger size and sieving to provide granules of size in the range of from 0.5 mm to 4 mm.
30. 30. A method of controlling perennial woody weeks in an area of land comprising broadcasting onto the land the hexaxinone granules, according to any one of claims 19 to 29.