IE46973B1 - Herbicidal compositions - Google Patents

Description

The present invention relates to herbicidal compositions and a method of combatting weeds employing such compositions.

The active substance combination of aminotriazole (3-amino-1 ,2, k triazole) and water-insoluble herbicide^)has until now been conventionally formulated as a wettable powder prepared by blending, milling and mixing the various ingredients to achieve as much homogeneity as practicable. Such powders have considerable disadvantages e.g. they are dusty, difficult to pour, have a low bulk density and frequently require pre-creaming to form a lump-free paste before dilution to the desired final concentration.

In an attempt to overcome these difficulties the active ingredients have been formulated as suspension concentrates in water ( also known as flowahles). These concentrates avoid many of the problems caused by the wettable powders but do exhibit one major drawback in their poor low temperature stability. The presence of the water insoluble herbicide^) suppresses the solubility of aminotriazole which under normal circumstances is 28g/lOO ml at 25°C. The result of this suppression is that the temperature at which the aminotriazole begins to crystallise out of the solution is raised. This temperature will be referred to as the freezing point of the concentrate.

Exposure of such concentrates to low temperatures, particularly during storage, will result in separation of the aminotriazole. In order to obtain the correct dosage of active ingredients the user will now he forced to either employ only whole packages or maintain the concentrates at - 2 46973 a sufficiently high temperature to avoid freezing. Either method involves waste and/or expense and is usually impracticable. This represents a very real problem to which no satisfactory solution has yet been proposed.

It has now been found that by including a suitable acid in such suspension concentrates the freezing point thereof is lowered to temperatures below those normally encountered by the user.

The present invention therefore provides a suspension concentrate having a pH from 4 to 6 which contains as active ingredients aminotriazole and one or more water insoluble herbicides together with an amount of an inorganic or organic acid sufficient to achieve said pH value, which acid is incapable of forming an insoluble salt with aminotriazole.

The total amount of active substance present in such concentrates is between 40$ and 60$,preferably 50$ w/v.

When simazine is the water insoluble herbicide employed, the ratio of aminotriazole to simazine is between 0.5:1, to 1:2 by weight, preferably 0.6:1.

The pH of the concentrates of the invention must be neither too low - the chemical stability performance of the active ingredients could be detrimentally affected -, nor too. high because the desired lowering of freezing point would not occur.

Accordingly, the pH value is between 4 and 6,preferably 4.5 to 5.5· - 3 46973 Examples of suitable acids are inorganic mineral acids such as hydrohalic acids in particular hydrochloric acid, nitric acid, sulphuric acid and sulphamic acid and organic acids such as formic acid, acetic acid, lactic acid, glycollic acid and citric acids.

Certain acids e.g. phosphoric and ascorbic are not suitable for use in the present invention since they tend to form insoluble salts with aminotriazole.

As examples of water insoluble herbicides there may be mentioned for example triazines such as simazine, (2-chloro-4,6-bis(ethylamino)-s-triazine); atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine ); terhuthylazine(2-tert-butylamino-4-chloro-6-ethylamxnos-triazine). Substituted ureas such as (1,3-dimethyl-3,5trifluoromethyl-1,3,A—thiadiazol-2-yl)—urea, Monuron[3-(4chlorophenyl)-1,1-dimethylurea and Diuron[3-(3,4-dichlorophenyl)1,1-dimethylurea,Uracils such as Bromacil(5-bromo-6-methyl-3S-butyluracil), Carbamates such as Karbutilate(m-(3,3dimethylureidoJphenyl tert-butyl-carbamate) and phenoxyalkanoic acids such as 2,4-D(2,4-dichlorophenoxyacetic acid).

The term «water-insoluble as used herein means both totally and predominantly water insoluble or only sparingly soluble in water.

The concentrates of the invention can he diluted to the desired concentration and used in combatting weeds in fclie usual marmAy, - 4 4 G 9 7 3 The concentrates of the invention may be prepared in the conventional manner by intimately admixing the various components. As adjuvants commonly used in the preparation of suspension concentrates there may he mentioned :thickening agents, antifoaming agents, antifreezing agents, surfactants ( as well as optionally other active substances such as further herbicides, insecticides, fungicides, bactericides etc.) and microbicides to prevent mould growth.

The active ingredients, acid and other adjuvants may be mixed in a one stage process or, if more convenient, any of these components may be pre-mixed and the remainder added in a subsequent operation.

The compositions of the present invention are advantageous relative to analogous wettable powder compositions in addition to low temperature storage stability in that: a) as the particle size of the water-insoluble component e.g. simazine in the present compositions ( at least 95$ < 1 b) tlie suspensibility of the present compositions is in the range of 90-100$ so that the material will remain in suspension for a considerable time - even when not agitated; c) the user can add the required quantity of the composition of the invention directly to the spray tank without any need to pre-cream - resulting in a much more easy application; d) no undesirable evolution of dust occurs during the pouring of the present herbicidal compositions from their containers; and e) because of their higher bulk density relative to wettable powder, the present compositions offer advantages in terms of transportation and storage.

The following Examples serve to illustrate the present invention. All percentages given in the description and Examples are weight/volume unless otherwise stated. - 6 46973 Examples 1-4 In each of the following Examples the basis for the concentrate was formed by GESATOP L ( a commercially available herbicidal suspension concentrate containing about 5OOg/litre of simazine as active ingredient). 1. % 70.0 GESATOP L (Gesatqp is a registered Trade Mark) 18.8 Aminotriazole ( pure) 1.2 Ethane - diol 4.0 Concentrated hydrochloric acid 0.05 Antifoaming agent (Silicone emulsion M 10) 1.5 Reax 88B (Lignosulphonate dispersing agent) 0.09 Rhodapol 23 (xanthan gum) to 100. by vol. Tap water pH after formulation: 5± 0.2 2. 70.0 GESATOP L 18.8 Aminotriazole ( pure) 1.2 Ethane-diol 4.0 Concentrated hydrochloric acid 0.05 Antifoaming agent (silicone emulsion MIO) 1.5 Reax 45L (combined wetting and dispersing agent) 0.09 Rhodapol 23 (xanthan gum) to 100 by vol. Tap water pH after formulation: 5 + 0.2 _ 7 . 6973 3· $ 70.0 18.8 1.2 4.0 0.05 1.5 0.2 0.09 to 100% by vol. pH after formulation: 4. 70.0 18.8 1.2 4.0 0.05 1.5 0.2 0.09 to 100. by vol. pH after formulation: 5 ± 0.2 Stability (i) The compositions prepared according to Examples 1-4 were all found to be physiochemically stable after 3 months storage at -5 °C and after a minimum of two years storage at 15-25°C.

GESATOP L Aminotriazole (pure) Ethane - diol Concentrated hydrochloric acid Antifoaming agent (Silicon emulsion MIO) Reax 88B 36% Formaldehyde solution Rhodapol 23 Tap water + 0.2 GESATOP L Aminotriazole (pure) Ethane - diol Concentrated hydrochloric acid Antifoaming agent (Silicone emulsian MIO) Reax 45 L 36% Formaldehyde solution Rhodapol 23 Tap water (ii) To demonstrate the dependence of the freezing point on pH, the concentration of concentrated hydrochloric acid in each formulation was varied and its effect on the freezing point of formulations containing simazine as the water-insoluble herbicide was observed.

The following results were obtained: pH Freezing Point 7 0 - 2?C 6 -3- 2°C 5-5 -5* 2 °C 5 -ei 2’C 4.5 -10°C 4.0 <-10°C

Claims (13)

1. CLAIMS:1. A suspension concentrate having a pH value of from 4 to 6 which contains, as active ingredients, aminotriazole and oite or mare water.-insoluble 5 herbicides, together with an amount of an inorganic or organic acid sufficient to achieve said pH value , which acid is incapable of forming an insoluble salt with aminotriazole

2. A suspension concentrate as claimed in Claim 1 wherein the total amount of active substance is between 10 40$ and 60% weight/volume.

3. A suspension concentrate as claimed in claim 2 wherein the total amount of active substance is 5°$ weight/volume.

4. A suspension concentrate as claimed in any of 15 the preceding claims wherein simazine is the water-insoluble herbicide.

5. A suspension concentrate as claimed in Claim 4 wherein the ratio of aminotriazole to simazine is between 0.5:1 to 1:2 by weight. 20

6. A suspension concentrate as claimed in Claim 5 wherein the ratio of aminotriazole to simazine is 0.6:1 by weight. _ 1046973

7. A suspension concentrate as claimed in any of the preceding claims wherein the pH value is from 4.5 to 5·5·

8. A suspension concentrate as claimed in any of 5 the preceding claims wherein the acid present is a hydrohalic acid, nitric acid, sulphuric acid, sulphamic acid, formic acid, acetic acid, lactic acid, glycollic acid or citric acid.

9. A suspension concentrate as claimed in Claim 1 10. Substantially as described with reference to any of the Examples.

10. A method of producing a suspension concentrate as claimed in Claim 1 comprising intimately admixing the various components. 15

11. A method as claimed in Claim 10 wherein one or more of a thickening agent, an antifoaming agent, an antifreezing agent, a surfactant, a further herbicide, an insecticide, a fungicide, a bactericide and a microbicide is also admixed. 20

12. A method as claimed in Claim 10 or 11 wherein the ingredients are mixed in a one-stage process, or any of the components is pre-mixed and the remainder are added in a subsequent operation.

13. - A method of producing a suspension concentrate as claimed in Claim 10 substantially as described with reference to any of the Examples. ll. A suspension concentrate when produced by 5 a method claimed in any of claims 10 to 13.