DK145213B - HERBICID CONCENTRATE OF 2-ETHOXY-2,3-DIHYDRO-3,3-DIMETHYLBENZOFURAN-5-YL METHANSULPHONATE - Google Patents

Description

in 1452 13

The invention relates to a herbicidal concentrate of ethhofumesate which is 2-ethoxy-2,3-dihydro-3,3-dimethyl-benzofuran-5-yl-methanesulfonate.

Ethofumesate is a known, water-insoluble herbicide that is difficult to formulate into stable concentrates. As a result, it has heretofore been formulated only as wettable powder or as a low concentration emulsifiable concentrate of the compound.

The wettable powder is difficult to precisely measure, is prone to cake formation during storage, and can be blown away by the wind when used, thereby causing adverse effects on neighboring areas. In addition, the active ingredient tends to be separated from any diluted formulation prepared for use by dispersing the wettable powder in water.

The emulsifiable concentrate contains toxic and expensive hydrocarbons as solvents for the active ingredient. In addition, the content of active ingredient can only be up to 20% due to its low solubility in the solvents. Thus, it is a bulky formulation that is expensive to store and transport. Through the present invention, these difficulties are overcome by providing a formulation that can contain water as the sole carrier and which is stable at concentrations up to 700 g / liter of active ingredient. Since the concentrate is aqueous, it is inexpensive to produce and can be easily diluted with additional water when used.

The concentrate according to the invention contains in aqueous suspension from 100 to 700 gAiter 2-ethoxy-2,3-dihydro-3,3-dimethyl-benzofuran-5-yl-methanesulfonate, whose particles have a diameter of at least 85%. below 5 microns measured with Coulter Counter, and, as a surfactant, a block copolymer of ethylene oxide and propylene oxide, and it is characteristic that said block copolymer has a reversible thickening temperature as defined in the description of 45 ° C or greater and is to ϊ.

Present in the concentrate in an amount of 0.5 to 30% by weight based on the weight of said sulphonate present, and further comprising from 0.5 to 10 g / liter of a Xanthomonas hydrophilic colloid and 5 from 0 5 to 30% by weight based on the weight of said sulfonate present by an anionic deflocculant.

The term "reversible thickening temperature" as used in the present specification with claims is understood to mean the temperature at which a pronounced change in viscosity can be observed upon heating a ground aqueous suspension consisting of 48.5% (wt. / volume) pure ethofumesate, 1.5% (w / v) of the surfactant, 4.85% 15 (w / v) of "Dyapol PFS" (deflocculant consisting of a sodium salt of an anionic sulfonated condensation product from Yorkshire Chemicals Limited ) and 0.1% (w / v) of Antifoam RD (Dow Corning anti-foaming agent).

The suspensions can be prepared by a process of mixing the ingredients. The ethofumesate having a larger particle size than desired in the suspension is conveniently mixed with other ingredients (including the block copolymer of ethylene oxide and propylene oxide) and ground to the proper size e.g. in a ball mill. The suspending agent may conveniently be admixed as a solution or suspension thereof in water.

The suspensions in question preferably contain a total of from 100 to 600 g / liter of ethofumesate, especially 30 at least 300 g / liter, e.g. 500 g / liter.

The concentrate is then usually diluted with water prior to use, usually such that the concentration of the ethhofumesate is from 0.05 to 5 g / liter and preferably from 0.5 to 5 g / liter. However, larger concentrations can be used if desired, especially if small volumes are desired.

As mentioned, the suspensions contain the suspending agent, a Xanthomonas hydrophilic colloid, at a rate of from 0.5 to 10 g / liter.

The hydrophilic Xanthomonas colloid (also known as xanthangurami) is preferably that. available on the market under the trade name "Ke1zan" from Kelco Compa-5 new. A Xanthomonas hydrophilic colloid is a colloid produced by fermentation by a bacterium of the genus Xanthomonas, such as Xanthomonas campestris.

The block copolymer of ethylene oxide and propylene oxide used as a surfactant is preferably obtained by the addition of ethylene oxide to a polyoxypropylene chain to form a polyol. More preferred are such polyols having a polyoxypropylene chain having a molecular weight greater than 1500 and especially greater than 1800. Further, it is preferred that the polyol contains from 30 to 70% by weight, e.g. from 40 to 60% by weight, e.g. ca. 50% by weight ethylene oxide. Preferred polyols of this kind are those available under the trade name "PluTOnic1® from Ugine Kuhlmann, especially those having the code numbers F68, F127, L62, L103, P75, 20 P94, P104 and P105.

The surfactant is preferably present in a weight range of from 3-15% of the content of the ethhofumesate.

The anionic deflocculant may be any ordinary anionic deflocculant. However, it is preferred to use a sodium salt of an anionic sulfonated condensation product, e.g. what is available from Yorkshire Chemicals Limited under the trade name "Dyapol DFS".

The deflocculant is preferably present in an amount of from 3 to 15% by weight based on the weight of the ethhofumesate.

The suspensions may thus contain further compatible water-miscible materials as carriers, although water is preferably the only carrier.

The suspensions may contain additives, e.g. anti-foaming agents (e.g., a silicone-based anti-foaming agent) e.g. in amounts of 0.02 to 2% by weight of the continuous phase, antifreeze agents (e.g. ethylene glycol) e.g. in an amount of 5-20% by weight of the continuous phase, or preservatives (e.g. formaldehyde) e.g. in an amount of 0.02 to 2 wt% 5 of the continuous phase.

Other compatible pesticides, e.g. herbicides, insecticides or fungicides, or plant growth regulators may be present in the concentrated suspension or in the diluted preparations. It is particularly useful to add one or more herbicides, especially herbicides useful for the selective control of weeds in sugar beets.

Alternatively, the present compositions may be used before or after one or more of the herbicides listed above.

The ratio of the total amount of ethofumesate present to the additional or each additional herbicide present is preferably from 1: 5 to 5: 1 part by weight.

The additional or any additional herbicide may be incorporated into the present suspension either before dilution of the concentrate if it does not adversely affect the stability of the concentrate or after.

The suspensions have excellent stability and the concentrates retain their homogeneous and free-flowing nature particularly well during storage even at fluctuating temperatures. Furthermore, they have excellent dispersibility in the medium used to dilute them prior to use. The suspensions are especially valuable for controlling weeds in crops, e.g. beet, sunflower, tobacco, grass and cruciferous crops, and especially beet.

The amount of use is usually 0.5 to 8 kg of 35 ethhofumesate per liter. hectares, e.g. 1-4 kg per acres.

The suspensions can be used before or after sowing the crop. They can be used after the sprouting or, preferably, before the sprouting.

5 145213

The invention is further illustrated in the following examples.

Example 1

An aqueous liquid suspension concentrate was prepared from the following as described below:

Technical ethofumesate, 98% purity 510 g

Pluronium% 75 (block copolymer prepared by condensation of ethylene oxide with molecular weight polyoxypropylene chain about 2050, wherein the polyoxyethylene constitutes 50% by weight of the 10 block copolymer); from Ugine Kuhlmann

Company 15 g

Polyphon H (sodium salt of sulfonated

Kraft Lignin from Westvaco Corporation) 15 g

Antifoam RD emulsion (silicone-based anti-foaming emulsion from Dow Corning 15 Corporation) 0.5 g

Ethylene glycol 80 g

Xanthan gum (Kelzan from Kelco Company) 2 g

Formaldehyde 1 g

Water up to 1 liter of about 510 ml 20 Water (360 ml), Antifoam RD emulsion, Pluronic P75, Polyphon H, ethylene glycol and ethofumesate were successively added to a running ball mill. The mixture was ground until more than 95% by weight of the ethofumesate had a particle size below 5 microns as determined by Coulter Counter measurement. A solution of xanthan gum and formaldehyde (a preservative for xanthan gum) in water (150 ml) was then added to the milled product, using a vane stirrer until homogeneous. The pH of the suspension was adjusted to 30 to 7.0 with 10% aqueous hydrochloric acid.

comparison Example

In comparison, a suspension concentrate was prepared identical to that described in Example 1 except that the suspension was omitted.

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Example 2

The suspension concentrate of Example 1 was compared in a temperature storage experiment (the temperature was maintained at 40 ° C in one experiment and in another 5 experiments the temperature was maintained successively for 12 hours at 12 ° C and 38 ° C over a period of 6 months). the suspension concentrate according to the comparative example. After the end of the storage period, it was found that the suspension of Example 1 had no hard precipitate and could still flow while the suspension of the comparative example. was precipitated, leaving a hard precipitate of ca. 50% by volume of a clear supernatant liquid. Further, it was found that the precipitate could not be resuspended in the supernatant liquid by methods which one would expect a consumer to be able to use, including stirring and shaking.

Example 3

Determination of the reversible thickening temperature.

A mixture of ground technical ethofumesate (98% pure, 1020 g), Dyapol PFS (Yorkshire Chemicals Limited deflocculant; 100 g) Antifoam RD (Dow Corning anti-foaming agent; 2 g) and water (844 ml) was milled in 5 l / 2 hours to obtain a milky consistency suspension having a density of 1.12. Part of this suspension (8.5 ml) was then mixed with 1.5 ml of a 10% aqueous solution of Renex 690 (a surfactant from Atlas Chemical Industries Company). Thereafter, the mixture was slowly warmed to a water bath while measuring its temperature. At 45 ° C, a significant thickening of the suspension occurred, which was readily observed by the experimenter. The suspension remained in this state upon further heating, but, upon cooling to below 45 ° C, returned to its previous consistency. Therefore, the reversible thickening temperature for Renex 690 was determined as 45 ° C.

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Many other surfactants were similarly rated, with the results set forth below:

Pluronic ® P75> 62 ° C

Pluronic ® F127> 62 ° C

5 Pluronic ® P105> 62 ° C

Pluronic ® P94> 62 ° C

Pluronic ® L103> 62 ° C

Pluronic ® F68 51 ° C

Pluronic ® L6 2 49 ° C