Patent Application
20060094602
The invention relates to an adjuvant composition for use with agrochemicals. More particularly the invention relates to an adjuvant composition having pH adjusting characteristics.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date part of common general knowledge; or known to be relevant to an attempt to solve any problem with which this specification is concerned.
There is a growing trend to produce adjuvants to improve the efficacy of agrochemicals, including herbicides. For example, farmers add adjuvants which may contain lipophilic solvents, surfactants, plant nutrients or water conditioners to tank mixes of agrochemicals in order to improve their efficacy. Most pesticide applications benefit by the addition of one or more of the adjuvant types above.
One of the factors which farmers must consider when using agrochemicals is the pH of the water being used as the carrier for the tank mix. High pH water commonly comes from aquifers that flow through basic minerals and ground water emitted from alkaline soils. Low pH water can come from minerals, acidic soils and more recently from surface waters that result from acid rain.
Some agrochemicals are sensitive to the pH of the overall composition and may actually be substantially degraded if the pH is outside a certain range. High pH water may cause alkaline hydrolysis resulting in the degradation of the chemical. Low pH water can also cause chemicals to breakdown by acid hydrolysis. The organophosphate insecticides are known to be sensitive to high pH as is dimethoate whilst the sulphonylurea herbicides break down more quickly at low pH. Because many pesticides can be degraded by alkaline or acidic conditions, it is common for pesticide manufacturers to recommend a preferred pH range usually in the neutral to slightly acidic range 5 to 7, however some agrochemicals may have a preferred pH outside of this range. In addition to the problem of chemical degradation associated with high or low pH, uptake of foliar herbicides can be affected by the pH of the spray solution applied.
Inorganic buffers are available and will easily adjust the pH of a spray solution into the required range but do not provide the other adjuvant effects which are often necessary to optimize pesticide applications. The use of inorganic buffers will usually require additional adjuvants to be used for pesticide applications to obtain optimum results.
As a result, there have been attempts to produce adjuvants which will enhance the effectiveness of pH sensitive agrochemicals by incorporating buffering components with other adjuvant components (eg lipophilic solvents and/or surfactants). Previous attempts to address this issue by formulating adjuvant compositions which modify pH have assumed that the water being used would be alkaline and therefore merely added an acidifying agent such as propionic acid or phosphate esters such as an alkylaryl polyethoxy phosphate ester. As a result, these compositions cannot be used with neutral or acidic waters since the resultant pH may be too low for the agrochemical to be effective.
There is thus a need for an adjuvant composition which can be used to facilitate use of an agrochemical in water that has a low pH, a neutral pH or a high pH.
It has surprisingly been found that the combination of C1 to C6 organic carboxylic acids, boric acid and organic amines can be readily formulated with lipophilic solvents and/or surfactants. This enables the preparation of adjuvant compositions having pH adjusting capabilities as well as pH adjusting compositions having other adjuvant characteristics such as wetting, penetration, spreading and solubility. Both types of compositions are able to enhance the efficacy of an agrochemical when mixed with this pH adjusted water.
According to a first aspect of the invention an adjuvant composition having pH adjusting capabilities for use with water to be used for spraying an agrochemical is provided, said adjuvant composition comprising:
Preferably, the amount of boric acid is in the range from 0.5 to 5.0, more preferably 1.0 to 3.0. Preferably, the amount of organic carboxylic acid is in the range from 0.5 to 5.0, more preferably 1.0 to 3.0. Preferably, the amount of organic amine is in the range from 1 to 25.
According to a second aspect of the invention, there is provided a pH adjusting composition having other adjuvant properties for use with water to be used for spraying an agrochemical is provided, said pH adjusting composition comprising:
Preferably, the amount of boric acid is in the range from 0.5 to 5.0, more preferably 1.0 to 3.0. Preferably, the amount of organic carboxylic acid is in the range 5 to 30. Preferably, the amount of organic amine is in the range from 1 to 25.
According to a third aspect of the invention, there is provided a method for adjusting the pH of water to be used for spraying an agrochemical, said method comprising the step of adding an adjuvant composition according to the first aspect of the invention or a pH adjusting composition according to the second aspect of the invention to the water.
In a preferred embodiment, the adjuvant composition and pH adjusting composition in use adjusts the pH of the water to be used for spraying an agrochemical to raise the pH of low pH water or lower the pH of high pH water to a pH in the range of from 3.5 to 9. Preferably, the pH is adjusted to within the range of from 5 to 8.
Some pesticide products may have a preferred pH at which they are known to be more stable or more efficacious. The adjuvant composition and pH adjusting composition can be prepared to adjust the pH of water toward a particular pH within the ranges specified by carefully selecting the proportions of acids (i) and (ii) and alkaline (iii) components. For example, a pH adjusting composition with 1.5% w/w boric acid, 25.5% w/w propionic acid and 9.4% w/w of oleylamidopropylamine will adjust the pH of water towards 4, whereas an adjuvant composition with boric acid 3.5% w/w, propionic acid 1.5% w/w and cocoamine 9.7% w/w will adjust the pH of water towards 8.5. The pH adjusting compositions having higher proportions of buffering system are more effective at adjusting pH than the adjuvant compositions according to the first aspect of the invention. However, the adjuvant compositions will be used when more effective other adjuvant properties such as wetting, spreading or penetration are desired. It will depend on the specific situation whether a composition according to either of the first or second aspects of the invention is used.
Suitable mineral oils are known to those skilled in the art and typically include aliphatic hydrocarbons with average carbon number from 15 to 30 or may be denoted by their viscosity with suitable examples being 60 to 150 second solvent neutral oils.
The vegetable oils are any suitable vegetable oils known to those skilled in the art including medium chain triglycerides and canola, corn, sunflower and soyabean oils.
If alkyl esters of fatty acids are used then a majority of unsaturated fatty acids are preferred. Without wishing to be bound by theory, unsaturated fatty acids are preferred because they are more effective as surface modifiers and remain as usable liquid at lower temperatures. There are innumerable variations of the esters of fatty acids which may be produced from the natural oils and fats such as lard, tallow and vegetable oils, such as canola, corn, sunflower and soyabean oils, or from specific blends produced by fatty acid manufacturers or from fatty acids produced by synthetic means. The alkyl moiety may be derived from simple alcohols such as methyl, ethyl, propyl or butyl alcohols.
The range of surfactants suitable for use as the carrier will be well known to those skilled in the art and may be selected from nonionic, cationic or anionic surfactants and should be chosen for either or both of the following purposes:
Examples of suitable surfactants include, but are not limited to, sodium diisooctylsulphosuccinate, sulphated alcohol ethoxylates, alcohol ethoxylates, alkylaryl ethoxylates, fatty acid ethoxylates, fatty acid glycerol esters, fatty alkanolamides, fatty amine ethoxylates, fatty acid sorbitan esters, ethoxylated fatty acid sorbitan esters, alkyl polyglucosides, fatty amine oxides and fatty betaines.
The organic carboxylic acid containing up to six carbon atoms may be a simple carboxylic acid such as acetic or propionic acid or may contain other functionality such as hydroxyl, ether or additional carboxyl groups. Examples include, but are not limited to, malic, maleic, or citric acids.
Examples of suitable organic amines include, but are not limited to, alkanolamines, or primary or tertiary alkylamines such as fattyamines, dimethylalkylamines and alkylamidoalkyldimethylamines. Specific examples includes oleylamidopropylamine, cocoamine, oleylamine, triethanolamine, oleylamidoethanolamine, di(C10)methylamine, dimethylcocoamine and oleylpropylenediamine.
For adjuvant compositions and pH adjusting compositions where the carrier is a surfactant, then the organic amine may be an alkanolamine such as mono-, di-, or triethanolamine, which should provide adequate solubility of the buffering salt into the surfactant.
For adjuvant compositions and pH adjusting compositions where the carrier is primarily a lipophilic solvent, then the organic amine may be selected from primary amines or tertiary dimethylamines of the structure (CH3)2N—R wherein R contains an alkyl group of at least 8 carbon atoms and may contain other chemical moieties. For example, the tertiary dimethylamines may be selected from dimethylalkylamines or other substituted alkyldimethylamines such as alkylamidoalkyldimethylamines. Examples of such tertiary dimethylamines are dimethylcocoamine, oleylamidopropyldimethylamine and oleo adducts prepared from N.N-dimethylaminoethanol and N.N-dimethylethylenediamine. Other tertiary amines such as di(C10)methylamine may also be suitable.
In a preferred embodiment of the invention, the adjuvant composition and pH adjusting composition may further comprise other solvents which improve the physical characteristics of the formulation such as reduced viscosity or homogeneity over a wide temperature range. Examples of suitable other solvents include glycols such as glycerine, hexylene glycol or 1,3-butanediol, glycol ethers such as dipropyleneglycol monomethyl ether, simple alcohols such as ethanol or isopropanol or water.
According to a fourth aspect of the invention, a buffering system for use with water to be used for spraying an agrochemical is provided, said buffering system comprising
According to a fifth aspect of the invention, there is provided a method for adjusting the pH of water to be used for spraying an agrochemical to a pH in the range of from 3.5 to 9 comprising the steps of:
The invention will now be further explained and illustrated by reference to the following non-limiting examples.
The following components are used in the examples:
The following Compositions were prepared according to the invention for use in the examples:
Buffering Characteristics of Compositions 1-20
In this example, Compositions 1 to 20 were added to high and low pH water to compare pH adjusting characteristics.
A stock of 4 waters, adjusted to unit pH's with NaOH or HCl as appropriate, had their pH measured after additions of 0.2%, 0.5% or 1% of each the 20 compositions. A further water was adjusted to pH 9 and contained 1 WHO hardness, wherein 1 WHO contains 342 ppm of CaCO3. Water containing ions such as CaCO3 are generally more difficult to adjust the pH than water free of such ions.
In the tables, a (-) means that the composition was not tested at that pH.
All of Compositions 1 to 20 demonstrated an ability to adjust pH. Most of the Compositions (1-4, 6, 8, 9, 11-20) adjusted the pH of both the high and low pH water to within the range of about 5 to 8. Higher usage rates of Compositions 1 to 20 tended to adjust the pH to a preferred pH more effectively.
Composition 5 adjusted the water to a narrow range around pH 5. Composition 7 was designed to adjust the pH of the compositions to about 4, whilst Composition 10 adjusted the pH toward about 8.5. These examples show that the adjuvant composition can be prepared to target a particular pH within the specified range. Further, the compositions with higher proportions of buffering system as per the second aspect of the invention (Compositions 7 and 20) were more effective at adjusting pH than compositions according to a first aspect of the invention. Where the agrochemical is particularly sensitive to pH then a composition according to the second aspect of the invention is preferred.
Glyphosate Herbicide Efficacy
In this example, adjuvant compositions according to the invention were tested for efficacy with the herbicide RoundUp CT in water at initial pH of 7 and 9.
Initial pH 7 Water
Annual ryegrass seedlings were treated with RoundUp CT and the various adjuvant compositions at 70 g and 140 g glyphosate/hectare in water initially at pH 7. The Control was not sprayed. The adjuvants were used at the rates specified.
The following table sets out the fresh weight after 14 days. The lower the fresh weight, the more effective the treatment.
The results show that at pH 7, the adjuvants according to the invention provided enhanced efficacy for RoundUp CT. Composition 1 which adjusted the pH to around pH 7 may be more effective than Composition 7 which adjusted to pH 4, or the acidifier adjuvant LI-700.
Initial pH 9 Water
The following mixtures containing RoundUp CT and adjuvants at 70 g and 140 g glyphosate/hectare were prepared water initially at pH 9 then left for 4 hours before spraying.
Annual rye grass seedlings were treated with the spray compositions and collected after 14 days and the fresh mean weight measured.
Both Composition 1 and LI-700 provided significant herbicidal efficacy compared with the RoundUp CT alone showing that the buffering and acidifying characteristics of these adjuvants may be providing protection for the pesticide.
Glufosinate Herbicide Efficacy
In this example, adjuvant compositions according to the invention were tested for efficacy with the herbicide product BASTA which may be sensitive to low pH water. All treatments were applied at 250 g a.i./Ha and sprayed at 64 L/Ha. Adjuvants were added to the pH adjusted water before the herbicide then the mixture allowed to stand for either nil, 4 hours or overnight (16 hours) as indicated before applying to the plants (annual ryegrass 2-3 leaf stage). The time interval between mixing and spraying was chosen to allow time for any degradation of the herbicide to occur which may be associated with the non-neutral pH waters.
Results are reported as mean Fresh Weight grams per plant 12 days after treatment.
There is no significant difference between the treatments at pH 9, 7 or 4. However at pH 2 the use of Composition 1 significantly increased efficacy when compared with either no adjuvant or the acidifier adjuvant LI-700 indicating that the pH adjusting characteristics of Composition 1 may be protecting the pesticide from the acidic conditions.
The word ‘comprising’ and forms of the word ‘comprising’ as used in this description and in the claims does not limit the invention claimed to exclude any variants or additions.
Modifications and improvements to the invention will be readily apparent to those skilled in the art. Such modifications and improvements are intended to be within the scope of this invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| PS 2228 | May 2002 | AU | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/AU03/00553 | 5/9/2003 | WO | 8/4/2005 |
