Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to pesticidal formulations, and more
particularly to herbicidal formulations in the form of aqueous emulsions
containing high concentrations of herbicidal 2,6-dini~roaniline derivatives,
such as trifluralin, and to methods of making such fonmulations.
Herbicidal 2,6-dinitroaniline deri~atives characteristically possess
a me~ting point ~hich is less than 200 C and a solubility in water at
25C which is less than 100 parts per million by weight. Such herbiGidal
derivatives have hitherto been formulated in a concentrated solution in
a substantially water-immiscible organic solvent such as xylene, together
with an emulsifying agent. These concentrated formulations are dispersed
in large volumes of water prior to spraying on crop land
The preparation of 2,6-dinitroaniline derivativ~s, such as trifl~ralin,
and their activity as pre-emergent herbicides is described in, ior example,
U.K. Patent Speciiication No, 917,253.
Although the known concentrated formulations of herbicidal 2~6-
dinitroaniline derivatives have proved to be highly effec~ive in enabling
large quantities of the pesticides to be stored in a relatively compact
i-orm whilst being readily dispersible in large volumes of water in
preparation for spraying, they do suffer from the disadvantage that bulk
storage of such formulations carries the unavoidable fire risk associated
with storage of organic solvents, and the commercial penalty of the high
cost of organic solvents. Hitherto it hPs not been possible to provide
an aqueous pesticidal formulation containing a high concentration of a
¦ herbicidal 2,6-dinitroaniline derivative and having satisfactory storage
stability.
- According to the present invention there is provided a herbicidal
ormulation in concentrate fo~m belng an aqueous emulsion comprising
10% to 75% by weight of a herbicide being at least one herbicidal
~
J~
1~
!
2~6-dinitroaniline derivative having a solubili~y in water at 25 C
less tha~ 100 parts per million by weight and a melting point in
the range from -10 C to 150 C7
07. to 607~ by weight of a substantially water-immiscible solvent~
the herbicide and the solvent forming a homogerea~ disperse phase,
0.5% to 10% by weight of an emulsifylng agent, having a hydrophile-
lipophile balance (HLB) of at least 12, and 15% to 70% by weight of
an aqueous solution of an inorganic salt, said aqueous solution having a
pH not greater than 9, the concentratlon of the inorganic salt in the
aqueous solution being at least 5% by weight.
The herbicide may be a single herbicidal 2,6-dinitroaniline derivative
or a mixture of two or more such derivatives. If the herbicide is a mixture
of 2,6-dinitroaniline derivatives, it is the mixture which must fulfil the
melting point and water-solubility requirements.
Similarly the inorganic salt may be a single salt, such as sodium
chloride, a double salt, such as sodium alum~ or a mixture oE salts. The
salt should be such that the aqueous solution is substantially neutral, i.e.
it has a pH not grea~er than 9. Examples of salts which have been found to be
useful include sodium chloride, potassium chloride, ammonium chloride,
calcium chloride, magnesium chloride, ammonium nitrate, sodium acetate9
ammonium carbonate, copper sulphate, magnesium sulphate, sodium sulphate,
alumin;um sulphate, sodium ferric sulphate and potassium dihydrogen phosphate
Salts giving rise to strongly alkaline aqueous solutions, i.e~ solutions
having a pH greater than 9, such as sodium carbonate, potassium carbonate
and potassium monohydrogen phosphate should be avoided.
The emulsifying agent ~.ay consist of a single emulsifying agent
or it may be a blend of emulsifying agents, and it may be a non-ionic,
anionic or cationic surfactant, a blend of two or more non-ionic surfactants,
a blend of non-ionic and anionic surfactants or a blend of non~ionic and
cationic surfactants. Non-ionic surfactants are preEerred. The hydrophile-
_ 3 _
~3
~ i.
:`
lipophile balance (HLB) of ~he emulsifying agent should be at least 12.
The substantially water immiscible solvent may be a single organic solven
or it may be a blend of two or more such materials. It is essential for the
solvent to be such as will dissolve the herbicide in the formulation and
to be substantially immiscible with the aqueous phase of the emulsion.
Desirably the solvent should no~ be soluble in the aqueous phase to an
extent greater than 0.2% wiw, and preferably the solubility of the solvent
in the aqueous phase is 0.2% w/w or less. The solven~ may have a
melting point at o~ above ambient temperatures. However, if this is
) thë case, a mixture of the herbicide and the solvent in relative
proportions equal to their relative proportions in the herbicidal
formulation should desirably be liquid at ambient temperature~ Examples
of suitable solvents include aromatic hydrocarbons, such as xylenes,
trimethylbenzenes and polynuclear aromatic hydrocarbons, such as naphthalene,
alkylnaphthalenes and anthracene, halogenated aromatic hydrocarbons9 such
as o-chlorotoluene, aliphatic hydrocarbons, such as decane, and other
organic solvents such as camphor, and miscible blends of two or more of
such solvents. In the event that the herbicide is a liquid such as
isopropalin, in some circumstances a herbicidal formulation according
to the invention may not include any water-immiscible solvent other than
the herbicide itself.
Preferably formulations in accordance with the invention contain from 15%
to 70% by weight of the herbicideg from 0~/0 to 45% by weight of the solvent,
from 0 9% to 6% by weight of the emulsifying agent and from 20% to 40% by
weight of the aqueous solution, the concentration of the inorganic salt in
¦ the aqueous solution being from 10% to 20% by weight.
¦ Examples of suitable 2,6-dinitroaniline derivatives include trifluralin,
b fl r~lin, isopropalin, ethaliluralin, dinitramine, dipropalin, oryzalin,
- 4 _
lfi7~l
4-methylsulphonyl-2,6-dinitro-N3N~dipropylaniline, ~luchloralin, penoxalin,
profluralin and dlbutalin. These derivatives fall within ~he scope of
the formula I:
\ N /
~ 02N ~ 2
where Rl is hydrogen, C2 4 alkyl or chloroethyl, R2 is Cz 5 alkyl, chloroethyl,
2-methallyl or cyclopropylmethyl, R3 is hydrogen; methyl or amino and R4
i9 trifluoromethyl, Cl 3 alkylg -S02NH2 or -S02CH3.
Pesticidal formulations in accordance with the present invention preferabljr
have one or ~ore of the following features:
(a) the herbicide is a 2,6-dini~roaniline derivative of formula II:
~ 3
~here Rl is C2 4 alkyl or chloroethyl, R~ i5 C2 4 alkyl, chloroethyl or 2-
Methallyl and R3 is hydrogen or amino,
(b) the herbicide is a 2,6-dinitroaniline derivative oE formula II
wherein R is ethyl or propyl, R is propyl, butyl or 2~[nethallyl and R is
¦ hydrogen,
~1 _ 5 _
l! l
(c) the herbicide is trifluralin9
(d) the herbicideforms 15% to 65% by weight of the formulation,
(e~ the herbicideforms at least 40% by weight of the formulation,
(f) the herbicideforms at least 45% by weight of the formulation,
S (g) the herbicideforms not more than 60% by weight of the
formulation,
(h) the solvent forms not more than 50% by weight of the formulation,
(i) the solvent forms 10% to 45% by weight of the forrnulation,
(;) the solvent forms at least 15% by weight of the formulationJ
(k) the solvent forms not more than 2S% by weight of the formulation9
(1) the solvent is an aromatic hydrocarbon solvsnt,
(m) the solvent is xylene or a mixture of xylene and naphthalene;
(n) the emulsifying agent forms at least 0.~% by weight of the form-
ulation,
(o) the emulsifying agent forms at least 2% by weight of the
formulation,
(p) the emulsifying agent forms at least 3% by weight of the formulation,
(q) the emulsifying agent forms not more than 7% by weight of the
formulation,
(r) the emulsifying agent forms not more than 6% by weight of the
formulation,
(s) the emulsifying agent is a non-ionic surfactant or a blend of
two or more non-ionic surfactants,
(t) the emulsifying agent has a calculated hydrophile-lipophile balance
of at least 12,
(u) the emulsifying agent has a calculated hydrophile-lipophile
¦ balance in the range of from 14 to 18,
(v) the emulsifyi~g agent has a calculatad hydrophile-lipophiLe balance
~ in th ange of from 15 to 17,
lfi7~ ~
(w) the emulsifying agent has a calculated hydrophile-lipophile balance
of substantially 16,
(x) the aqueous solution forms not more than 50% by weight o~ the
formulation,
(y) the aqueous solution forms not more than 40% by weight of the
formulationl
(æ) the aqueous solution orms not more than 35~/0 by weight of the
formulation,
(aa) the aqueous solution forms not more than 25~/o by weight of the
formulation, -
(ab) the aqueous solution forms at least 10% by weight of the formulation,
(ac) the aqueous solution fonms at least 15% by weight of the
formulation,
(ad) the aqueous solution forms at least 20% by weight of the
formulation,
(ae) the aqueous solution additionally includes urea at a concentration
up to ~% by weight of the aqueous solution,
(af) the inorganic sslt is selected from sodium chloride, potassium
chloride and calclum chloride,
(ag) the inorganic salt is sodium chloride.
¦ When the herbicide is isopropalin it preferably forms 60% to 75% by
weight of the formulation, no solvent is included, the emulsifying agent
forms 2% to 6% by weight of the formulation and ~he aqueous solution forms
19% to 38% by weight of the formulation.
In accordance with a preferred aspect of the present invention there is
provided a herbicidal formulation in concentrate form being an aqueous
emulsion comprising:
45% to 60% by weight of trifluralin,
l~otO 25% by weight of a substantially water-immiscible aromatic
hydrocarbon solvent, the trifluralin and the solvent fo~ming
a homogeneous disperse phaseJ
3% to 6% by weight of a non-ionic surfactant or a blend of such
surfactants, having a calculated hydrophile-lipophile balance in
the range of from 15 to 17, and
22Z to 3270 by weight of an aqueous solution of sodium chloride9 the sodium
chloride concentration being in the range 10% to 18% by weight of
the aqueous solution, the aqueous solution additionally including
0% to 5% of urea by weight of the solution.
The invention also provides a process for preparing a herbicidal
~ormulation in concentrate orm which process comprises agitating together
a homogeneous organic phase containing lOqo to 75% by weight of the
formulation of a herbicide being at least one herbicidal 2,6-dinitroaniline
having a solubility in water at 25 C less than 100 parts per million by weight
and a melting point in the range of from -10 C to 150 C, and 0% to 60% by
~eight of the formulation of a substantially water-immiscible solvent, and an
aqueous phase consisting of 15% to 707n by weight of the formulation of an
aqueous solution of an inorganic salt, said aqueous solution having a
pH not greater than 9, the concentration of the inorganic salt in the
aqueous solution being at least 5% by weight, with 0.5% to 10% by weight
of the formulation of an emulsifying agent, having a hydrophile-liphophile
balance (HLB) of at least 12, until a stable emulsion is formed therefrom.
__ _
In the method of the present invention it is preferred for at least part
or the emulsifying agent to be dissolved in the organic phase prior to
agitation of the organic phase and the aqueous phase. The herbicide is
preferably dissolved in the solvent, the resulting solution is filtered and
the emulsifying agent is dissolved therein before addition thereto of the
aqueous phase and agitation. The agitation is desirably continued until
3'~
~ - 8 -
the mean droplet diameter of the organic phase is observed to be in the
range 8 to 14 microns. Urea may be dissolved in the aqueous solution up
to 5% by weight of the aqueous solution prior to agitation of the organic
phase and the aqueous phase.
The invention further includes a method of inhibiting growth of weeds
which method comprises disperslng in a large volume of water a herbicidal
formulation according to he invention, and applying the dispersion formed
thereby to a locus in which it is desired to inhibit the growth of weeds.
In the examples of the invention a number of emulsifying agents and
solvents are referred to by their commercial names. The emul-ifying
agents are Remcopal NP 30, Remcopal PONF, Remcopal 25, Remcopal 0.11,
Remcopal 273, Tensagex DP24~ Stepan agent 555-66A, Stepan agent 555-66B,
Ethomeen T.25, Renex 650, Brij 72 and Brij 78. The solvents are Aromasol H
and"Solvesso 100" The chemical natures of these commercial materials
insofar as they are known to the Applicant are as follows :
'~emocopal NP30" - an ethoxylated nonyl phenol containing on average
30 ethoxy groups and having a hydrophile-lipophile
balance (HLB) of 17,5,
'~emocopal PONF" - an ethoxylated nonyl phenol containing on average
11 ethoxy groups and having an HLB of 13.7.
'~emocopal 25" - an ethoxylated oleo-cetyl alcohol containing on
average 25 ethoxy groups and having an HLB of 16.2.
'~emcopal 0.11" - an ethoxylated octyl phenol containing on average
10.5 ethoxy groups and having an HLB of 13.8,
'~emcopal 273" - an ethoxylated tridecylalcohol containing on
average three ethoxy groups and having an HLB of
~ 6~ !
¦ l-14 incl~si~e. The terms bearing these s~perscript ~merals
are all trademarks,
f~
Stepan'agents 555-66A - blends of calcium dodecylben~ene sulfonate
and 555-66B and alkylphenoxy polyoxyethylene ethanols,
E~hom~nT.25 - ethylena oxide condensation product of primary
i`atty amines containing on average 15 ethoxy groups~
"Renex 650" - an alkylaryl e~erhaving an HLB of 17.1,
Brij 72 - a polyoxyethylene stearyl ether having an HLB of 4.9
Brij 78 - a polyoxyethylene stearyl ether having an HLs of 15.
"Aromasol H" - an aromatic hydrocarbon solvent consisting
predominantly of isomeric trimethylben7.enes and
having a specific gravity of 0.879 and distillation
range from 168C to 200C,
Solvesso 100 - an aromatic hydrocarbon solvent consisting
predominantly of Cg hydrocarbons but also containing
some C8 and C10 hydrocarbon and having a specific
gravity of 0.872 and distillation range from 156C
to 180C~
-10-
! .
.
,71
The inve~tion will be better understood from the following illustrative
: Examples:
EXA~PLE 1.
S Triflu~alin~ technical (96% pure) ....... .. .. .. 500 gms
Xylene .. ,. O~ ,. ,. .. .. ,. 230 gms
Emulsifying agent --(blend of 24.4 gm "Remcopal NP30"
and 15.6 gm "Remcopal PONF"). 40 gms
Aqueous solution of sodium chloride (15% w/w) .. O. 310 gms
TOTAl: 1080 gms(1 1itre )
The trifluralin was dissolved in the xylene with gentle ~arming to
50 C and the resulting solution was filtered through a fine grade ~Whatman
No. 42) filterpaper. The emulsifying agent was added to the solution
lS of trifluralin in xylene, and dissolved with gentle warming to 50 C. The
.- aqueous solution of sodium chloride was added to the xylene solution with
agitation. The resulting emulsion was opaque and orange-yellow in colour.
: EXAMPLE 2.
Triflur~lin ..... .. .. .. ., .. .. 500 gms
. Xylene .......... ,. ......... .~ ... .. .. .. 180 gms
Naphthalene (technical grade).~ .. .. .. .. 60 gms
Emulsifying agent as in Example 1 .. .. .. .. 40 gms
¦ Aqueous solution of sodium chloride (15% wtw) ....... .. 310 gms
,5 ¦ TOTAL: 1090 gmS(l litr~ )
. 1-
. ¦ *TRADEMARK
I ~
The trifluralin and naphthalene were dissolved in the xylene
with gentle warming to 50 C, and the remaining steps in forming the
emulsion were as in Example l. The emulsion was opaque and orange-yellow
in colour.
The ~on~ulations of Examples l and 2 were tested for stability by
storing for one month at temperatures of -lO C~ -2 C, room temperature,
40 C and 50 C. There was no noticeable deterioration of the formulations
under these conditions. Both formulations remained free flowing at -18 C,
which was the lowest temperature at which they were tested.
Both emulsions flowed easily and were readily dispersed with sLight
agitation in large volumes of water.
EXAMPLE 3.
A formulation was prepared in identical manner as in Example l
except that the emulsifying agent used was 40 gms of'~ensagex DP 24"
supplied by Tensia S.A. This emulsifying agent is an anionic surfactant.
The resulting formulation was a stable orange-yellow opaque emulsion.
.
EXAMPLE 4.
A formulation was prepared as in Example 3 except that the
emulsifying agent used was 40 gms of a blend of 75% by weight
Stepan agent 555-66A and 25% by weight Stepan agent 555-66B supplied
by Stepan Chemical Company. Both Stepan agents are blends of anionic
,5 and non~ionic surfactants. The resulting opaque emulsion was stable and I was orange-yellow in colour.
¦ EXAMPLE 5.
A formulation was prepared as in Example 3, except that the emulsifying
agent used was 40 gms of Ethomeen T.2~ supplLed by Anmour ~ess Chemicals
~30
*Trademark -12-
1~ 1
Limited. This emulsifying agent is a cationic surfactant. The resulting
emulsion was stable, was opaque in appearance, and was ozange-yellow in
colour.
~XAMPLE 6.
.` A formulation was prepared as in Example 2, except that the aqueous
; solution was 310 gms of an aqueous solution of sodium chloride (17% w/w).
:.
EXAMPLE 7.
A formulation was prepared as in Example 1 except that the aqueous
solution was 310 gms of an aqueous solution of sodium chloride (13% w/w)
and urea (4Z wlw).
.
.~ BXA~uPLB a .
: 15 A formulation was prepared as in Example 1, except that the aqueous
.~ solution was 310 gms of an aqueous solution of potassium dihydrogen phosphate
.~ (13~/o w/w)~
EXAMPLE 9.
20 A formulation was prepared as in Example 1 except that the aqueous
solution was 310 gms of an aqueous solution of ammonium ferric sulphate
(1370w/w)~
EXAMPLES 10 to 15.
Formulations were prepared as in Example 1 except that the
~ following wer used as the emulsiEying ageDts :
.~ 30
I -13-
L671
.
EXAMPLE Emulsifying Agent
Remcopal 25 (36.7 gms) + Remcopal 0.11 (3.3. gms)
ll Renex 650 ~36.4 gms) ~ Brij 72 (3.6 gms)
12 Renex 650 (15.6 gms~ + Brij 78 (24.4 gms)
13 Remcopal NP30 ~18.3 ~ms) + Remcopal PONF (11.7 gms)
14 Remcopal NP30 (12.2 gms) + Remcopal PONF (7.~ gms)
Remcopal NP30 (6.1 gms) ~ Remcopal PONF (3.9 gms)
'' 10
EXAMPLE 16.
A formulation was prepared as in Example 1~ except that in place of the
xylene there was employed 235 gms of Solvesso 100
EXAMPLE 17.
A formulation was prepared as in Example 1, except that in place of the
xylene there was employed 240 gms of Aromasol H.
6XA~PLE 18.
Trifluralin, technical (96% pure) .. .. .. .. 625 gms
Xylene .. .. .. .. .. .. .. ~ 181 gms
Emulsifying agent (36.7 gms of Remcopal 25
a~d 3.3 gms of Remcopal 0.11) .. .. 40 gms
~5 Aqueous solution of sodium chloride (15% w/w) ,. .. 266 6m~
TOTAL: 1112 gms (1 ~re
The above formulati4n was prepared by a similar method to that used
in Example 1.
11
~ 1l 14-
1, . .
;71
~XA~L~ 19.
Trifluralin, technical (96% pure) .. .. .. . .. 688 gms
Xylene .. .. .. .. .. .. .. .. 119 gms
Emulsifying agent ( 24.4 gms of Remcopal NP30
and 15.6 gms of Remcopal PONF .. 40 gms
Aqueous solution of sodium chloride (15% w/w) .. .. 289 gms
TOTAL: 1136 gms (1 litr
This formulation was prepared by a similar method to that used
in Example 1.
The emulsions of Examples 6 to 19 were all stable emulsions opaque
in appearance and orange-yellow in colour.
: EXAMPLE 20.
Benfluralin~ technical (95% pure) ....... .. .. .. 190 gms
Xylene .. .. .. .. .. .. .. .. 317 gms
Naphthalene (technical grade) . .. .. .. .. 104 gms
Emulsifying agent ( 38.9 gms of Remcopal 25
.and 1.1 gms of Remcopal 273 ) .. 40 gms
Aqueous solution of ammonium chloride (13% w/w)..... ~. 362 gms
TOTAL: 1013 gms(l litr~
The above formulation was prepared by a similar method to that
used in Example 1. The resulting stabLe emulsion was opaque and was
. yellow in colour.
.
L.E`~7i
EXAMPLE 21.
Benfluralin, technical (95% pure) .. .. .. .. 190 gms
Xylene .. .. .. .. .. .. .. .. 277 gms
Cyclohexanone .. .. .. .. .. .. .. 130 gms
SEmulsifying agent ( 33.3 gms of Remcopal NP30
and 6.7 gms of Remcopal 273) ..40 gms
Aqueous solution of sodium chloride (15% w/w) ,. .. 362 gms
TOTAL: 999 gms(l litr~
This formulation was prepared by a method similar to that used in Example
l. The resulting emulsion was identical in appearance to that of Example 20.
EXAMPLE 22.
Ethalfluralin, technical t95% pure).. .. .. .. 347 gms
Xylene ........... .. .. .. .. .. ., .. 361 gms
Emulsifying agent ( 33.3 gms of Remcopal NP30
and 6.7 gms of Remcopal 273 ~ .. 40 gms
Aqueous solution of sodium chloride (15% w/w) .. .. 289 gms
TOTAL: 1037 gms(l litr~
The above formulation was prepared by a similar method to that of
Example 1. The resulting stable emulsion was opaque in appearance and
yellow in colour.
EXAMPLE 23.
¦ A formulation was prepared as in Example 22, except that the aqueous
solution was 282 gms of an aqueous solution of potassium chloride (13% w/w).
,
The resulting ~ulsion was similar in :ppea~ance to that o E Examp le 22.
-16-
`
~ ,
EXAMPLE 24.
A formulation was prepared as in Example 22 except that the aqueous
solution was 289 gms of an aqueous solution of calcium chloride (13% w/w).
S The resulting emulsion was similar in appearance to those of Examples 22 and 23.
EXAMPLE 25.
Isopropalin, technical ~90% pure) .. .. .. .. 800 gms
Emulsifying agent ( 33.3 gms of Remcopal NP30
and 6.7 gms of Remcopal 273 ) .. 40 gms
Aqueous solution of sodium chloride (15% w/w) .. .. 33~ gms
TOTAL: 1178 gms(l litre
The emulsifying agent was dissolved in the isopropalin with gentle
warming. The aqueous solution of sodium chloride was added with agita~ion.
The resulting stable emulsion was opaque and dirty orange-yellow in colour.
It should be noted that the emulsifying agent of each of Examples 1 to
25 hss a calculated hydrophile-lipophile balance of substantially 160
In the emulsions of Examples 1 to 25 above it has been found that the
mean droplet diameter of the organic phase is in the range of from 8 to
: 14 microns. These emulsions have been found to disperse readily when added
to 100 volumes of water and to remain substantially dispersed for several
hours. Such dispersions are readily applied to crop land by conventional
2S means such as spraying, and are therefore usable in a similar manner to the
known concentrated formulations.
The emulsions of Examples 1, 2 and 4 to 25 exhiblt particularly good
stability under a variety of storage conditions. Coalescence of droplets
and formation of upper or lower aqueous layers is very slow and samples may
~ 17-
` I .
. I
be stored for at least a year at 25 c or 40 C without appreciable coalescence.
The emulsion of ~xample 7 has been found to have very good stability under
high temperature storage conditions and has remained a stable emulsion after
storage for several weeks at 60 C. At the lower ends of the temperature scale,
these emulsions are generally stable at temperatures of -2 C to -10 C
and exhibit good resistance to crystallisation. In general they do not freeze
until the temperature drops to about -25 C.
The formulations of Examples 1 to 25 present a reduced fire hazard
compared with the known emulsifiable concentrate formulations of 2,6-dinitro-
aniline herbicidea in organic solvents such as xylene.
