FI70769C - HERBICIDISKT VERKSAM FENOXIALKANKARBOXYLSYRAESTRARS LAGERSTABIL KONCENTRERAD EMULSION OCH DESS FRAMSTAELLNINGSFOERFARANDE - Google Patents

Abstract

Storage-stable, herbicidally- active compositions in the form of a concentrating aqueous emulsion comprising 30 to 75% by weight of one or more herbicidally-active phenoxyalkanecarboxylic acid esters, 0.1 to 5 parts by weight referred to the completed emulsion of one or more oil-soluble emulsifiers which are soluble in the esters and have an HLB value of 9 to 16, and 0.1 to 3 parts by weight referred to the completed emulsion of one or more alkali metal salts of single or multiple unsaturated fatty acid taurides or fatty acid alkyl taurides as watersoluble dispersants, the emulsion having a viscosity of 50 to 3,000 mPa.s., a droplet size of 1 to 5 mu m and a pH value of 6 to 9 and a process for the preparation of such emulsion which comprises forming a solution of the active ester and emulsifier and mixing it with an aqueous solution of the dispersant to form a homogeneous mixture.

Description

i 70769

A durable, concentrated emulsion for storing herbicidally active phenoxyalkanecarboxylic acid esters and a process for its preparation. - Herbicidal active ingredient of phenoxyalkanecarboxylic acid esters is stable, concentrated emulsion or framställningsförfarande.

The present invention relates to an aqueous, storage-stable, concentrated emulsion of one or more herbicidally active phenoxyalkanecarboxylic acid esters and to a process for their preparation.

Phenoxyalkanecarboxylic acids are among the most common herbicides. They are used as their amine salts, mineral salts or also as esters thereof, e.g. as isopropyl, butyl, butyl glycol or 2-ethylhexyl esters.

The advantage of the ester is that it penetrates plants faster and thus its use is less dependent on the weather. Their solubility in water is low, but they are still soluble in oils such as diesel, fuel oil, petroleum ether, xylenes, cyclohexanone, isophorone, or highly purified hydrocarbons. Usually the ester is dissolved in such a solvent, an emulsifier is added to the solvent to form a concentrated, clear, emulsifiable solution (emulsion concentrate, EC) which is diluted for use in the field with water to form an oil-in-water emulsion.

According to AT-PS 307 802, it is also possible to prepare an oil-in-water high viscosity formulation consisting of the active ingredient, mineral oil, water and formulation auxiliaries for the storage of pesticides. This formulation is inverted for application shortly before use with an additive consisting of a solvent and a dispersant into a readily flowing water-in-oil dispersion: "Inverse Emulsion".

However, both formulation methods, both the commonly used emulsion concentrate and the high viscosity dispersion, 70769 have considerable disadvantages due to the solvent used. All solvents commonly used in them, like most organic solvents, are at least hazardous to health and, above all, flammable. Thus, highly purified, predominantly aliphatic hydrocarbons have a flash point of 40 to 80 ° C, an isophorone has a flash point of 93 ° C, cyclohexanone has a flash point of 44 ° C, and the most commonly used xylene has a flash point of only about 25 ° C.

Emulsion concentrates prepared with these solvents are thus also flammable, and to date there have been several stockpiles of both the manufacturer and the user.

On the other hand, it has now been found that with the use of certain excipients it is possible to prepare a storage-resistant, high-strength emulsion of herbicides which is made on an aqueous basis and which is therefore non-combustible and which is not harmful to health due to the solvent.

The fact that the aqueous medium can be used to prepare storage emulsions resistant to the storage of phenoxy esters is surprising, since the phenoxy esters are themselves soluble, albeit to a small extent, in water and can thus be saponified.

The present invention therefore relates to an aqueous, storage-stable, concentrated emulsion of one or more herbicidally active phenoxyalkanecarboxylic acid esters using an oil-soluble emulsifier and a water-soluble dispersant, characterized in that it contains one to more esters-soluble emulsifiers , having an HLB value of 9 to 16 and selected from the group consisting of a fatty acid polyethylene glycol ester, a polyethylene glycol ether of fatty alcohols, glycerides or alkylphenols,. polyoxyethylene and polyoxypropylene block polymers; early salts of mono- or polyunsaturated fatty acid taurides or fatty acid alkyl taurides, optionally together with conventional antifreeze agents and / or conventional antifoams, the active ingredient content of the concentrated emulsion being from 30 to 75% by weight, viscosity from 50 to 3000 mPa.s. 1 to 5 p and pH 6-9.

The highly concentrated emulsion according to the invention is prepared by mixing the individual reaction components or by mixing two solutions: Solution I contains a phenoxy ester or esters and a dispersant dissolved in the ester and optionally an antifreeze, thickener, antifoam or colorant.

Phenoxyester soluble or fat soluble emulsifiers cause the active ingredient to distribute into the outer phase. Examples of such emulsifiers having an HLB ("hydrophil-lipophil-balance") value of 9 to 16 are: Polyethylene glycol ester of fatty alcohols, polyethylene glycol ether of fatty alcohols, mono- or diglycerides and alkylphenols, further polyethylene glycol propylene polyol-polyol The substances can be used alone, in admixture with one another or in admixture with the ammonium, Ca, Mg, K, Na and Zn salts of alkyl (C8-C24) benzenesulfonic acids. Particularly suitable are fatty acid polyethylene glycol ester or polyoxyethylene-polyoxypropylene block polymers with alkylarylsulfonates.

Solution I has a concentration of fat-soluble emulsifiers of 0.15 to 10 parts by weight per 100 parts by weight of solution I, with a range of 2 to 4 parts by weight being particularly preferred.

4,7769 In a concentrated, storage-stable emulsion, the emulsifiers have from 0.1 to 5% by weight, in particular from 1 to 3% by weight, of S.

The water-soluble dispersant stabilizes the inner phase distributions), e.g., by electrostatically charging the particles or by other repulsive forces, e.g., by an etheric blocking effect. Alkali salts of fatty acid taurides or fatty acid alkyl taurides, in particular sodium salts, are used as dispersants. Examples of such fatty acids, which often also occur in mixtures, are straight-chain or branched, saturated or mono- or polyunsaturated aliphatic carboxylic acids having 10 to 20 carbon atoms, such as lauric acid, palmitic acid, stearic acid, in particular myristic acid, myristic acid. The alkyl group of the fatty acid alkyl tauride is lower alkyl having 1 to 4 carbon atoms, especially methyl. Oisperpering agents may contain inorganic salts, in which case it is appropriate to keep the salt content low or to avoid it altogether.

Solution II usually contains 0.2 to 10 parts by weight of water-soluble dispersant, with a range of 1 to 3 parts by weight per 100 parts of solution II being particularly preferred. The concentration of dispersant in the concentrated, storage-stable emulsion is mostly 0.1 to 3% by weight, preferably 0.2 to 1% by weight.

Storage-resistant emulsions are usually prepared by first preparing an aqueous solution II of a dispersant containing any antifreeze, antifoam or thickener, and mixing it as a solution I with a liquid phenoxy ester or ester containing the emulsifier dissolved to form a homogeneous mixture. This mixing takes place with devices,, 2 which generate an emulsion shear rate between 10 • in4 -1

And 1 ° s. At high viscosity (3000 mPa) this 2 4 corresponds to the shear stress 3. 10 - 3. 10 Pa, for which hi 5 70769 are suitable

Homogenizers with Homorex, Ulta-Turrax or homogenisation head. At low viscosities (5 mPa.s), this corresponds to shear stresses of 5 to 500 Pa, which are suitable for devices such as vibrators, low-speed mixers, circulating pumps and similar devices. As the viscosity decreases with increasing temperature, it is also possible to use lower speed devices when using higher temperatures, about 50-90 ° C. In this case, a homogeneous distribution of droplets must be formed so that the droplet sizes are 1-5 [mu] m, preferably 2-3 [mu] m, in which case, in addition to the size of the individual droplets, it is important to have the narrowest possible distribution with low emulsion viscosity. It is also possible to add both solutions to the mixer and then mix, or to add them simultaneously with suitable dosing devices.

The viscosity of the concentrated emulsion is an essential factor for storage stability. The higher the viscosity, the better the storage stability. On the other hand, too high a viscosity in use is unfavorable in terms of water dilutability and spontaneous dispersibility. By means of the concentrated emulsion prepared according to the invention, it is possible to prepare stable and at the same time easily dilutable preparations with a viscosity in the range from 50 to 3000 mPa.s. On the one hand, in terms of dilutability and spontaneous dispersibility and on the other hand, stability (best results are obtained with viscosities between 500 and 1500 mPa.s.

Adjustment of the pH is still essential for the preparation of a stable emulsion. For each combination of active ingredient, emulsifier and dispersant, there is an optimal pH at which the emulsion is most stable.

This physical stability is in the alkaline range, but pH values above 9 must be avoided, as partial saponification of the ester may already begin in this range during long-term storage and at elevated temperatures. For acidic areas, pH values below 6 must be avoided, as fusion can occur in this area during long-term storage, i.e. the emulsion becomes more and more physically unstable. A pH range of 7 to pidetään is preferred.

All herbicidally active phenoxyalkanecarboxylic acid ethers, alone or in mixtures, are suitable for the preparation of the compound according to the invention, in particular esters having an alcohol chain length of -Cg, such as, for example, octyl esters of CMPP, MCPA or 2,4,5-T acids.

Because technical phenoxyalkanecarboxylic acid esters, due to their methods of preparation, usually have a pH of about 3 (measured as a 10% aqueous dispersion), the desired pH is adjusted with a conventional lye, e.g., sodium hydroxide or potassium hydroxide. The desired pH can be adjusted either during or after emulsion preparation. However, it is also possible to use purified, "neutral" esters, in which case it is not necessary to readjust the pH.

To provide sufficient cold resistance to the emulsions, conventional antifreeze agents such as ethylene glycerol, urea, glycol ether or other alcohols may be added. It is further possible to add known inorganic or organic thickeners, such as xanthan gum, sodium polyacrylate, carboxymethylcellulose, colloidal silicic acid or swellable clay minerals, such as bentonite, to control a certain viscosity. To reduce foaming, defoamers such as long chain alcohols, 2-ethylhexanol or cetyl alcohol, high polymeric glycols and especially silicones can be added.

For field use, the concentrated emulsions prepared according to the invention are completely diluted with water in the same way as the hitherto conventional combustible emulsion concentrates and can be applied by the same spraying devices.

The following examples illustrate the preparation and chemical and physical stability of substance i according to the invention.

The technical phenoxyalkanecarboxylic acid esters used comply with the guidelines recommended by WH0. Stability was examined in a storage experiment in which the temperature varied between -10 ° C and + 50 ° C over 24 hours. After four weeks of storage, it was measured.

1. Change in pH 2. Consumption of 0,01 N sodium hydroxide solution required to readjust the initial pH 3. Change in viscosity (measured with a Brookfield LVT viscometer, spindle 2, 6 rpm) 4. 0, Change in turbidity value of 01% emulsion correlated with change in droplet size (measured with a Lange turbidimeter in 100 ml cuvettes) 5. Percentage of supernatant 6. Melting (formation of an oily phase) 7. Re-emulsifiability.

The measurement values included in the examples are summarized in a table. The measurement results show that after a storage period of four weeks, when the temperature varied between -10 ° C and + 50 ° C in 24 hours, the change in measurement points 1, 2, 3, 4 and 5 was not more than 10% in any of the in the example given. No fusion occurred and any accompanying, unfused bottom precipitate could be completely re-emulsified.

Example 1

Solution Is 700 g 2,4,5-T-amyl ester, technical 20 g fatty acid polyethylene glycol ester e 70769 *

Solution II: 5 g Na-oleylmethyl tauride (95%) 25 g ethylene glycol, technical 1.3 g xanthan gum 443 g distilled water

Solution II was prepared and solution I was mixed with a Homorex mixer. After the addition, stirring was continued for another 10 min. at maximum speed, then adjusted to pH 7.25 with semi-normal sodium hydroxide solution, and stirred again, once for a while.

Example 2

Solution I: 350 g MCPA ethyl hexyl ester, technical 10 g fatty acid polyethylene glycol ester,

Solution II: 2,3-g palm kernel fatty acid methyl tauride sodium salt (30% aqueous solution with 7% NAC1 content) 10 g ethylene glycol 126 g distilled water

The procedure is the same as in Example 1. The pH was adjusted to 7.55.

Example 3 ·

Solution I 250 g 2,4-D-ethylhexyl ester 10 g fatty acid polyethylene glycol ester

Solution II 2.5 g of metastatic methyl tauride salt (30% aqueous solution with a NaCl content of 7%, fatty acid = palmitic acid / stearic acid) 10 g ethylene glycol 151 g distilled water 9 70769 k

The procedure is the same as in Example 1. The pH was adjusted to 7.6; C.

Example 4

Solution I: 250 g MCPA-ethylhexyl ester, technical 10 g fatty acid ethylene glycol ester 2.5 g fatty acid azide sodium salt (with inorganic and organic salts, fatty acid s Laurin / myristic acid) 10 g ethylene glycol 125 g distilled water

The procedure is the same as in Example 1. The pH was adjusted to 7.5.

Example 5

Solution I: 350 g CMPP-butyl glycol ester 10 g fatty acid polyethylene glycol ester

Solution II: 2.5 g Na-oleylmethyl tauride (25% aqueous solution) 145 g distilled water

The procedure is the same as in Example 1. The pH was adjusted to 7.5.

Example 6

Solution I: 350 g of 2,4,5-T-amyl ester 10 g of a mixture of nonylphenyl polyethylene oxide, polyoxyethylene polyoxypropylene block polymer (mp. 1800-1900) and alkylaryl sulphonate 10 k 7 0 7 6 9

Solution II: 10 g Na-oleylmethyl tauride (25% aqueous solution) 10 g ethylene glycol 150 g distilled water 1 g antifoam (herring emulsion)

The procedure is the same as in Example 1. The pH was adjusted to 8.0.

Example 7

Solution I: 350 g of 2,4-D-butyl ester 10 g of polyoxyethylene triglyceride and alkylaryl sulphonate

Solution II: 10 g Na-oleylmethyl tauride (25% aqueous solution) 10 g ethylene glycol 165 g distilled water

The procedure is the same as in Example 1. The pH was adjusted to 7.0.

i

Example 8

Solution I: 1200 g 2,4,4-T-ethylhexyl ester, technical, 30 g fatty acid polyglycol ester

Solution II: 9 g Na-oleylmethyl tauride (25% aqueous solution) 105 g ethylene glycol 6 g xanthan gum 1830 g distilled water 2 g antifoam (silicone emulsion)

1.68; g NaOH

70769 I

11 4

In a preliminary experiment, it was found that 0.56 g / l NaOH was needed to neutralize the mixture, after which this calculated amount of NaOH (1.68 g) was added to solution II. Thereafter, the solutions I and II metering pump device, which essentially consists of a circulation pump with a bypass, the feedback of the product and the outlet side paineenpitoventtiilistä. The optimal droplet distribution is obtained with a dosing pump / circulation pump ratio of 1:15 to 1:25. The pH was 7.8.

Example 9

Solution I: 429.5 g MCPA-ethylhexyl ester, technical 226 g 2,4,5-T-ethylhexyl ester, technical 1.2 g fatty alcohol polyglycol ester r.

Solution II: 25 g Na-oleylmethyl tauride (25% aqueous solution); 25 ethylene glycol 0.6 g xanthan gum 321 g distilled water

Solution I was added to solution II with stirring with a Homorex mixer and the pH of the solution was adjusted to 8.30 with a semi-normal NaOH solution brush i. The solution was further homogenized by pressing the emulsion at a pressure of 90 bar through the homogenization head.

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Claims (9)

1. Of one or more herbicidally active phenoxyalkanecarboxylic acid esters consisting of water-based, stock-stable, concentrated emulsion, in which is used an oil-soluble emulsifier and a water-soluble dispersant, characterized in that it contains one or more emulsifiers in a soluble emulsifier. 1-5% by weight based on the finished emulsion, whose HLB value is 9-16 and selected from a group consisting of fatty acid polyethylene glycol ester, polyethylene glycol ether of fatty alcohol, glycerides or alkylphenols, polyoxyethylene and polyoxypropylene segment polymers, blends of polymers, mixtures polyethylene glycol ether or polyethylene glycol polypropylene glycol segment polymer together with alkylarylsulfonates, and 0.1 to 3% by weight based on the final emulsion of one or more water-soluble dispersants from a group consisting of saturated or mono or polyunsaturated fatty acid aryl acid or aryl unsaturated fatty acid or , possibly until ammans with conventional antifreeze and / or conventional antifoaming agent, wherein the active substance content of the concentrating emulsion is 30 - 75% by weight, viscosity 50 - 3000 mPa.s, droplet size 1 - 5 μη »and pH 6-9, 2. Stable, concentrated emulsion according to claim 1, characterized in that fatty acid polyethylene glycol ester is used as ester-soluble emulsifiers. 3. Stable, concentrated emulsion according to claim 1 or 2, characterized in that Na-oleylmethyl tauride is used as water-soluble dispersing agent. 4. Stock stable, concentrated emulsion according to any of patent I? 70769, claims 1 to 3, characterized in that octyl ester of phenoxyalkanecarboxylic acid is used as herbicidal activity. 5. Stable, concentrated emulsion according to any one of claims 1-4, characterized in that it contains 1-3% by weight of emulsifier. 6. Stable, concentrated emulsion according to any one of claims 1-5, characterized in that it contains 0.2-1% by weight of dispersant. 7. Stable, concentrated emulsion according to any of claims 1-6, characterized in that its viscosity is 500 - 1500 mPa.s. Stock stable, concentrated emulsion according to any one of claims 1-7, characterized in that its pH is 7 - 8. 9. A process for preparing a herbicidally-active phenoxyalkanecarboxylic acid esters resistant, stock stable, concentrated emulsion, which uses oil-soluble emulsifier and water-soluble dispersant, characterized in that for the preparation of an aqueous concentrate having an active substance content of 30 to 75% by weight - 3000 mPa.s, a solution I is prepared from one or more phenoxyalkanecarboxylic acid esters and at least one ester-soluble, ionic or nonionic emulsifier, whose HLB value is 9-16, and selected from a group consisting of fatty acid polyethylene glycol ester, polyethylene glycol ether of fatty alcohols, glycerides or alkyl phenols, polyoxyethylene and polyoxy propylene segment polymers, mixtures of this polyethylene glycol ester, polyethylene glycol ether or polyethylene glycol ether.