CS232748B2 - Production method of concentrated in storage stable emulsion of herbicidely active esters of phenoxyalkanecarboxyl acids - 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

Phenoxyalkainecarboxylic acids are among the most commonly used herbicides. They use - in the form of their - salts with amines, - in the form of - mineral salts - or in the form of - esters, such as, for example, isopropyl ether, butyl esters, butyl glycol ester or 2-ethylhexyl ester. The advantage of esters is that they penetrate faster into the plant and, therefore, their use is less dependent on the weather. Their solubility in water is low, but they are soluble in oils such as oil. for - diesel - engines, - kerosene, petroleum ether, xylenes, cyclohexanone, - isophorone, or - highly - refined - hydrocarbons. Usually - the ester is dissolved in - such a solvent, an emulsifier is added to the solution - to form a concentrated, - clear, emulsifiable solution - - (emulsion concentrate, EC) which. - se. for water application to obtain an oil-in-water emulsion.

According to Austrian Patent Specification No. 30 802 802, it is also possible to produce a high viscosity concentrate for storing pesticides; consisting of active substances - mineral - oil, water and - auxiliary agents used for the manufacture of such oil-in-water formulations which, for application shortly before use, are converted by addition of an additive; consisting of a solvent - and a dispersant, - - - in; a thin dispersion of water in oil, the so-called "inverse emulsion".

However, both formulation types, i.e. the commonly used emulsion concentrate and highly viscous dispersions, have severe deficiencies due to the solvent used. All of the - usually used solvents - are like · most organic solvents - at least harmful to health, especially - however - flammable. So - they have - very pure, especially - - aliphatic hydrocarbons flash point - - 40 - to - - - 80 ° C, isophorone has - flash point 93 - ° C, cyclohexanone - has - flash point - 44 ° C - and most commonly used - xylenes - have a flash point - only about 25 ° C.

This means that in the past, storage fires - both at the manufacturer and at the user - have been flammable and emulsion concentrates in the past.

On the other hand, it has now been found that the use of certain adjuvants makes it possible to produce a highly concentrated, storage-stable emulsion of herbicidally active esters which is formulated on an aqueous basis and therefore is not flammable and - is not harmful to health because of the solvent. The possibility of using the - aqueous medium - for the - production - of the storage of the permanent emulsions of the phenxyesters is surprising - also because the phenoxyesters themselves are partially, although only slightly, soluble in water and can therefore be saponified.

Claims (1)

The invention therefore relates to a process for the production of a concentrated, storage-stable emulsion of herbicidally active esters. phenoxyalkanecarboxylic acids using an oil-soluble emulsifier. and a water-soluble dispersant, which process is characterized in that for the preparation of a water-based concentrate with an active substance content of 30 to 75% and an aqueous yellow of 50 to 3000 mPa.s. a solution I is prepared from one or more phenoxyalkanecarboxylic acid esters and at least one ionic or nonionic emulsifier soluble in said ester having a HLB value of 9 to 16, with 0.15 to 10 parts by weight of emulsifier per 100 parts by weight of this solution I; or mixtures of emulsifiers, this solution is · mixed with aqueous solution II, which · comprises at least one water-soluble dispersant from the group of the alkali salts of taurides or alkyltaurides · saturated or at least once unsaturated fatty acids and optionally a cold protection agent and / or an anti-foaming agent, wherein 100 to 100 parts by weight of the aqueous solution II comprise 0.2 to 10 parts by weight of a dispersant, and the resulting mixture is then homo- at 15 to 90 ° C. If necessary, the pH of the mixture is adjusted to between 6 and 9 before or after homogenization, and then the homogenate is diluted to 30 to 75% by weight of the active substance. The highly concentrated emulsion according to the invention is obtained by mixing the individual reactants or by mixing the two. solutions of which: · solution I · comprises said · phenoxy ester or phenoxy esters and an emulsifier soluble in these esters and solution II 'comprises an emulsifier · dissolved in water · · and optionally a frost protection agent, a thickening agent, an antifoam or a colorant . The emulsifiers soluble in these phenoxy esters, i.e. soluble in fatty compounds, disperse the active substances in the external phase. Examples of such emulsifiers having a HLB (hydrophilic-11-balance-balance) value of 9 to 16 are: polyethylene glycol esters of fatty acids, polyethylene glycol ethers of fatty alcohols, mono- or diglycerides and alkylphenols, and block polymers of polyethylene glycol with polypropylene glycol. mixed with each other or in admixture with ammonium, ammonium, calcium, magnesium, potassium, sodium and zinc salts of alkylbenzenesulfonic acids, in which the alkyl moiety contains 8 to 24 carbon atoms, especially suitable emulsifiers are polyethylene glycol esters of fatty acids or block polymers of polyoxyethylene · Polyoxypropylene · Together with alkylarylsulfonates. In solution I, emulsifiers soluble in fatty compounds are present in a concentration of 0.15 to 10 parts by weight per 100 parts by weight of solution I, with a content of 2 to 4 parts by weight being particularly preferred. In a concentrated storage emulsion, emulsifiers are present at a concentration of 1 to 3% by weight. The water-soluble dispersant stabilizes. dispersing · the internal phase, for example by electrostatic charge of particles or others. repulsive forces, such as, for example, sterile hindrance. Alkali salts, in particular sodium salts of taurides or alkyl fatty acid taurides may be used as dispersants. Examples of such fatty acids often used in the form of mixtures with one another are saturated or at least once unsaturated aliphatic carboxylic acids having from about 10 to 20 carbon atoms in the straight or branched chain, such as lauric, palmitic, stearic, myristic and especially oleic acids. The alkyl portion of the fatty acid alkyltaurides is an alkyl group having from 4 to 4 carbon atoms, in particular a methyl group. These dispersants may contain inorganic salts, it being expedient for the salt content to be as low as possible or not at all. In solution II, the water-soluble dispersant is usually present in a concentration of 0.2 to 10 parts by weight, with a particularly preferred concentration being 1 to 3 parts by weight per 100 parts by weight of solution II. The weight concentration of the dispersant in the concentrated storable emulsion is generally in the range of 0.1 to 3%, preferably 0.2 to 1%.