CA2018580A1

CA2018580A1 - Liquid formulations of herbicidal mixtures

Info

Publication number: CA2018580A1
Application number: CA 2018580
Authority: CA
Inventors: Gerhard Frisch
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1989-06-10
Filing date: 1990-06-08
Publication date: 1990-12-10
Also published as: JPH0324004A; DE3919036A1; EP0402769A1; AU5691890A

Abstract

Abstract of the disclosure Liquid formulations of herbicidal mixtures Stability problems and, in particular, instabilities caused by crystal growth, and changes in the biological availability of the active substances frequently occur in formulations of mixtures of water-soluble, salt-like active substances with active substances which are insoluble in water, depending on the composition.
The invention relates to particularly stable formulations of mixtures on the basis of linuron and active substances which are dissolved in salt-like form from the group comprising the phenoxyacetic and phenoxypropionic acids, glufosinate, glyphosate, dimethylphosphinoylhydroxyacetic acid and 1,1'-dimethyl-4,4'-bipyridinium chloride. The formulation auxiliaries are, essentially, lignin-sulfonates and salts of polymerized alkylnaphthalene-sulfonic acids.

Description

2 ~ 0 HOECHST AKTIENGESELLSCHAFT HOE 89/F 176 Dr.WE/AP

De~cription : .
Liquid formulations of herbicidal mixtures The invention relates to liquicl formulations of herbi-cidal mixtures containing linuron. Liquid formulations of herbicidal mixtures are those in which there are at least 2 active compounds in the ready-to-use formulation.
Formulations of mixtures are frequently advantageous compared with single-compound formulations because, for example, the action can be improved by combining active substances or the phytotoxic behavior of the herbicides can be markedly improved. Furthermore, the applicational properties can be improved and packaging can be mini-mized. Such formulations of mixtures are already known, for example, of isoproturon and CMPP salt solutions (EP-A 0,130,370) or of glufosinate, simazine and diuron (EP-A 297,305). In these examples the active substances isoproturon and diuron + simazine are present in finely-distributed solid form, and CMPP or glufosinate, respec~
tively, are in the form of a salt in aqueous solution.
These active substances which are dispersed in solid form have solubilities in water of not more than 55 mg~l of water at 20~C, so that there is a comparably very low risk of crystal growth at customary storage temperatures of -10 to +50C. Crystal growth in the formulations is to be avoided since it often result~ in instability of the dispersion. Moreover, the biological availability of the active substances and hence the herbicidal action when the formulation is used is a function of the crystal size. It is furthermore known to add colorants (EP-17,879 (US-4,441,919), DE-A-2,301,922 (VS-3,987,187)) which can inhibit crystallization to active substances which tend to show crystal growth because of their higher solubili-~ties, for exa~ple in water or oils.

It has now been found that, surprisingly, crystal growth can be prevented or substantially inhibited in 2 ~ 8 ~

formulationæ of mixtures of specific salt-like active substances with the herbicide 3-(3,4-dichlorophenyl)-1-methoxy-l-methylurea (linuron) which is dispersed in the form of a solid and which has a solubility in water of approximately 81 mg/l of water at 24C, when a specific combination of surfactants are used.

The invention relates to liquid herbicidal preparations (formulations of mixture~) containing a) 1-40 ~ by weight, preferably 8 to 35 % by weight, of linuron, b) 1-55 ~ by weight, preferably 8-38 % by weight, of at least one active substance, dissolved like a salt, from the group containing salts of phenoxyacetic and phenoxypropionic acids, glufosinate, glyphosate, dimethylphosphinoylhydroxyacetic acid and 1,1~-dimethyl-4,4'-bipyridinium chloride, c) 0.5-20 % by weight, preferably 0.5-6 % by weight, of a ligninsulfonate, d) 0.1-10 ~ by weight, preferably 0.1-5 % by weight, of a salt of a polymerized alkylnaphthalenesulfonic acid, e) 0-25 ~ by weight, preferably 0-15 % by weight, of customary auxiliaries from the group containing wetting agents, defoamers, thickeners, preserva-tives, antifreeze agents and humectants, and f~ 20-80 ~ by weight, preferably 30-65 ~ by weight, of water.

The formulation of the mixture contains linuron (con-stituent a) mainly as an active substance which is dispersed in solid form and only a small proportion of it is in dissolved form.
, ,'. ' .:
The active substances which are dissolved like salts are preferably herbicidally active derivatives of phenoxy-acetic and phenoxypropionic acid in tha form of the alkali metal salts, alkaline earth metal salts and ~` 2 ~

substituted or unsubstituted ammonium salts, in parti-cular of the sodium salts, potassium salts and ammonium salts, it being possible for the latter to be substituted by 1 to 3 subætituents from the group comprising C1-C4-alkyl, hydroxyethyl, hydroxypropyl, polyethoxyethyl or amino-(Cl-C4)-alkyl; salts of glyphosate and dimethyl-phosphinoylhydroxyacetic acid, in particular in the salt forms mentioned above by analogy, furthermore 1,1'-dimethyl-4,4r-bipyridinium chloride and, in particular, glufosinate in the possible salt forms which are men-tioned by analogy are likewise suitable. In this context, optically active compounds can be employed as a racemic mixture, as a mixture with a prevailing proportion of one enantiomer, or in pure enantiomeric form.

The herbicidal active substances which are mentioned specifically and some of their salt~ are known and most of them are described in Ch. R. Worthing's ~The Pesticide Manual", A World Compendium, 8th Ed. (1987) by the British Crop Protection Council, for example: linuron on pages 502/503, Substance No. 7690; glufonsinate, i.e. 2-amino-4-(hydroxy(methyl)phosphinoyl)butanoic acid on page 448/ Substance No. 6930; glyphosate, i.e. N-(phosphono-methyl)-glycine on page 449, Substance No. 6950; 1,1'-dimethyl-4,4'-bipyridinium chloride on pages 630 and 631, Substance No. 9320. ~his manual furthermore describes a series of herbicides of the phenoxyacetic-acid-type and phenoxypropionic-acid-type which can be employed accord-ing to the invention, such as, in particular, phenoxy-phenoxy-, pyridyloxyphenoxy- or heteroaryloxyphenoxy-acetic acids and -propionic acids. Dimethylphosphinoyl-hydroxyacetic acid and some of its salts are described in EP-A 0,106,114 tUS A 4,594,098).
: ,.. .: ~ .
The surfactant combination which the formulations of herbicidal mixtures contain according to the invention is principally composed of the two components (c) and (d), which, according to the invention, are essential for preventing crystal growth of linuron in a ready-to-use 2 ~ 8 ~
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mixture with one or more of the active substances which are dissolved like salts. Besides these two surfactant components/ this ready-to-use mixture can also contain customary auxiliaries, for example wetting agents, such as sodium salts of alkyl ether sulfates having 1 3 EO
(EO = ethyleneoxy units) tfor example ~enapol LRO, HOECHST), defoamers on silicone basis (for example the 0Silcolapse series by ICI or the antifoam agent SH
manufactured by Wacker). Inorganic and/or organic thickeners, for example on the basis of aluminum sili-cate, xanthane, methylcellulose, polysaccharide, alkaline earth metal silicate, gelatine and polyvinyl alcohol, can also be used; equally, if necessary, appropriate preser-vatives, such as, for example, those on the basis of formaldehyde, benzoic acid and triphenyltin. If neces-sary, it is also possible to ~dd antifreeze agents, for example urea and polyols, such as glycol, propylene glycol, glycerol and sugars.

Effective combinations of surfactants which effectively suppress crystal growth in linuron in the present case are preferably those which contain, as constituent (c), ligninsulfonates in their possible salt forms, for example (R)Vanisperse CB and/or (R~Ufoxane 3A manufactured by Borregard, Sarpsborg, Norway, and, as constituent (d), an Na salt of a polymerized alkyl-naphthalenesulfonic acid, such as (R~Darvan No. 1 (R.~. Vanderbuilt Comp.
Norwalk, CT 06855, USA data sheet 07.01.81). ~
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The abovementioned surfactants can be particularly preferably employed in the case of a ligninsulfonate (for example (R)Vanisperse CB, (R)Ufoxane 3A) in an amount of l- -6 ~ by weight and, in the case of an Na salt of a poly-merized alkyl-naphthalenesulfonic acid, such as ~R)Darvan No. 1) in an amount of 0.5-4 % by weight. ~

The active substance for the solid disperse phase ~ -(linuron) can be employed particularly preferably in an amount of 10-:20 ~ by weight, and the active substances which are dissolved like salts (for example glufosinate, ~
glyphosphate) in an amount of 10 to 30 % by weight. ~ -:
The formulations of herbicidal mixtures according to the invention may be prepared by mixing, according to the recipe in question, the constil:uents (a) to (f3 in any desired sequence and grinding the mixture to a fine powder. Howeverr they are pref~_rably prepared by first introducing a proportional amount of water into the reaction vessel and then adding, with stirring, the 1~ surfactants (c) and (d), if appropriate together with other auxiliaries (e), and then the active substances (a) and (b). The suspension which is first obtained is then micronized in a known manner (if necessary after a precomminution step) by means of ball mills (for example bead mills manufactured by Drais, Backofen, Netzsch), it being preferred that 90 % of the solid particles are markedly smaller than 10 ~m.

Examples of the formulations of mixtures which are unobjectionable in terms of use and which are stable on storage are listed in ~able I below. Comparison examples which show massive growth of crystals and/or which are instable, i.e., have a stability of less than 3 months in the storage test at 50C, can be seen in Table II. In the comparison tests, for example colorants were employed which slow down crystal growth in known cases; in other ~-examples of Table II, at least one of the surfactants (c) and (d) which are named as essential was replaced by similar surfactants, which showed that markedly better effects, such as, for example, stability on storage or less crystal growth, is achieved with the surfactant combination according to the invention.
, The amounts in the tables are to be understood as meaning percentages by weight, unless otherwise indicated.

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Explanations of Table II:
Fettrot 5B01 = Solvent Red 27, Color Index No. 26125 PV-Echtwei~ R01 = Pigment White 6, Color Index No. 77891 ~Soprophor PS 15 = alkyl polyethoxyether phosphate (10-40 E0) SE2 = defoamer on silicone basis Dispersant GN = sodium phenylsulfonate Dispersogen A = naphthalenesulfonic acid/formaldehyde condensation p:roduct Agrilan F 513 = neutral salt of a complex organic phosphate : :
Soprophor 3D33 = phosphoric ester of ethoxylated arylphenol Hoe S 3727 = diphenyl ether sulfonic acid/
formaldehyde condensate, neutralized with triethanolamine ~:~
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Claims

1. A herbicidal preparation containing a) 1-40 % by weight of linuron, b) 1-55 % by weight of at least one active substance, dissolved like a salt, from the group containing salts of phenoxyacetic and phenoxypropionic acids, glufosinate, glyphosate, dimethylphosphinoylhydroxy-acetic acid and 1,1'-dimethyl-4,4'-bipyridinium chloride, c) 0.5-20 % by weight of a ligninsulfonate, d) 0.1-10 % by weight of a salt of a polymerized alkylnaphthalenesulfonic acid, e) 0-25 % by weight of customary auxiliaries from the group containing wetting agents, defoamers, thick-eners, preservatives, antifreeze agents and humec-tants, and f) 20-80 % by weight of water.

2. The preparation as claimed in claim 1, which com-prises a) 8-35 % by weight of linuron, b) 8-38 % by weight of at least one active substance, dissolved like a salt, from the group containing salts of phenoxyacetic and phenoxypropionic acids, glufosinate, glyphosate, dimethylphosphinoylhydroxy-acetic acid and 1,1'-dimethyl-4,4'-bipyridinium chloride, c) 0.5-6 % by weight of a ligninsulfonate, d) 0.1-5 % by weight of a salt of a polymerized alkyl-naphthalenesulfonic acid, e) 0-15 % by weight of customary auxiliaries from the group containing wetting agents, defoamers, thick-eners, preservatives, antifreeze agents and humec-tants, and f) 30-65 % by weight of water.

3. The preparation as claimed in claim 1 or 2, wherein constituent (b) is glufosinate or glyphosate or a mixture of these, dissolved in like salt.

4. The preparation as claimed in one or more of claims 1 to 3, which comprises a) 10 to 20 % by weight of linuron, b) 10 to 30 % by weight of glufosinate, glyphosate or a mixture of these in the form of the respec-tive alkali metal salt, alkaline earth metal salt, ammonium salt or mono- to trisubstituted ammonium salt, c) 1 to 6 % by weight of a sodium ligninsulfonate, d) 0.5 to 4 % by weight of a polymerized Na salt of alkylnaphthalenesulfonic acid, e) 0 to 15 % by weight of customary auxiliaries and f) 30 to 65 % by weight of water.

5. The preparation as claimed in one or more of claims 1 to 4, wherein 90 % of the solid particles are smaller than 10 µm.

6. A process for manufacturing the preparation defined in one or more of claims 1 to 5, which comprises mixing the constituents (c), (d), (e) and (f) with stirring, then adding the constituents (a) and (b) and subsequently finely grinding the mixture with customary ball mills.

7. The use of the preparation defined in one or more of claims 1 to 5 for controlling undesired plant growth.