Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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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
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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
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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
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, ~ ~
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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). ~
~ ~ . -..-: . .
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
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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 ~:~
. ~,: ' .,,-
