Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2 3 2~ 12 `~
WO ~3/12652 ~Cr/US9;!/11~5~;6
~ . ` .
TITLE ~ -
STABILIZED GELLED--PASTE FORMUI~TIONS OF SULFONYLUREAS `
AND AN INJECTION SYSTEM FOR THEIR APPLICATION
BACK(~QUNI:~ OF T~ lVENTION
- This invention comprises "ge~led-paste"
compositions of ~ulfonylurea herbicides in an aqueous
chemically stabilized formulation which requires
vigorous mixing to disperse into aqueous media. This .
invention also compri e~ an improved method of dirert
injection to crops Of ~uch highly viscous crop
protection products, and a new and impro~ed apparatus
for the direct injection of qaid products.
Sulfonylurea harbicides and chemically stabilized
aqueous compositions thereof are known in the
literature. For instance, U.S. 4,936,900 teaches
chemically stabilized aqueous sulfonylurea or
agriculturally suitable sulfonylurea salt dispersions
in salt mediums which retain their effectiveness as
herbicides when formulated as aqueous suspensions
consisting of a sulfonylurea or its agric~lturally
suitable salt with a salt of a carboxylic or an
inorganic acid, or with mixtures of such carboxylic or
inorganic acid salts. The present invention teaches
the gellation o~ sulfonylureas in salt mediums thereby
preser~ing the stability of the typically unstable
sul~onylurea.
.~UMMARY OF THE INYENTION
The pre~ent invention teaches aqueous, chemically
stabilized, gelled-paste compositions of sulfonylurea
herbicides. These herbicidal compositions are prepared
from a suqpension o~ the type described by U.S.
4,936,900 by the addition of a water-soluble or water-
~wellabl~ synthetic, semisynthetic or biological .
polymer(s) which retains its gel characteriqtics in
WOg3~126~2 PCT/U~92/10556~ -.
212~312 2
salt mediums and which does not adversely affect the -.
chemical stability of the sulfonylurea or
agriculturally suitable salt of the suspension. ~:
One embodiment of the present invention is a -
process for making a sulfonylurea herbicide gelled-
paste composition, comprising combining a sulfonylurea
herbicide and one or a mixture of agriculturally
suitable salts of a carboxylic or inorganic acid in an Fs
aqueous medium to form a stable disper~ion of the
resultant sulfonylurea salt in the aqueous medium, then
blending one or more gelling agents into said
dispersion in sufficient amount to form a gelled-paste
compositionr which gelling agent is inert with re~pect -
to said herbicide. :
Another embodiment of the present invention
compri~es an aqueous herbicidal gelled-paste
sulfonylurea composition comprising, in admixture, in
weight percent ba3ed on total formulation weight:
(a) 1-60% of one or a mixture of ~ulfonylurea
herbicide active ingredient(~,
(b~ 1-40% of one or a mixture of
agriculturally suitable salts of ~ carboxylic or
inorganic acid, provided that the solubility of ~uch
carboxylic or inorganic acid salts in water at 5C and ::
25 a pH of about 6-10 is greater than or equal to 3% and ~.;
~urther provided that the pH of a 0.1 molar ~olution of
the carboxylic or inorganic acid salt is between 6 and
10,
(c) 0.5-20% of one or a mixture of a water-
soluble or water-swellable synthetic, semisynthetic or
biological polymer and that the water-soluble or water-
swellable ~ynthetic, semisynthetic or biological
polymer(s) used to form the gelled-paste is compatible
with the carboxylic or inorganic acid salts and does
W093/1~652 ~1 ~ 6 3 ~ ~ PCT/US921tO556
. .:
not lead to chemical decomposition of th~ sulfonylurea
or its agriculturally suitable salt,
~d) 0-10% of one or a mixture of dispersant,
and
(e) an aqueous medium forming the balance;
the sulfonylurea; polymer and a~ueous medium in amounts
effective to form a gelled-past~ composition, provided
that the sum of components (a) and (b) is no greater
than 85%.
A further embodiment of the pre~ent invention
comprises an aqueous herbicidal gelled-paste
sulfonylurea compo~ition comprising, in admixture, in
weight percent ba~ed on total formulation weight:
1-85% of one or a mixture of stablized
sulfonylurea herbicide,
0.5-20% of one or a mixture of water-soluble
or water-~wellable synthetic, semi~ynthetic or
biological polymer,
0-10% of di~persant, and
an aqueous medium ~orming ~he balance; -~
the sulfonylurea, polymer and aqu20u~ medium in
amounts effective to form a gelled-pa~te composition.
The compositions of this invention may also -~
optionally contain other water-soluble or water-
insoluble pesticides or crop pr~tection chemicals, more
specifically, pesticides ~elected from the class of
herbicides, fungicides, bactericides, insecticides, :.
insect antifeedants, acaricides, miticides, .-
nematocides, and plant growth regulants. -:
This invention further compri~es an apparatus for
direct injection of highly ~iscous crop pro~ection .
product~ for agricultural u~es. This invention
provides a means by which typical soluble agricultural
product forms, as well a~ atypical, non-traditional,
agricultural product forms (highly vi~cous insoluble
WO93/126S2 2 ~ PCT/US92/10556
gels and pastes), which would otherwise not be
dispersible into a carrier medium, can be dispersed
in~o a carrier medium.
This apparatus comprises, in combination:
(a) one or a plurality of container means for
housing crop protec~ivn product having an optional
inlet opening~ and ha~ing an outlet opening,
(b) pressure means associated with said container --
means for applying pressure to said crop protection
product within said container means for dispensing of
said crop protection product through said opening in
said container means,
(c) a mixing chamber, interconnected to said
opening in the container means, having a first inle~
opening for receiving the crop protection product
displaced from said opening of said container means,
and a second inlet opening for permitting entry of a :
carrier medium for said crop pro~ection product, and an
outlet opening,
(d) shearing means positioned within said mixing
chamber for dispersing said crop protection product
into said carrier medium to produce a sprayable
dispersion, and
(e) means for forcing a sprayable dispersion out
of the outlet opening of said mixing chamber to be
available for application onto agricultural crops.
The preferred container means is a cartridge which
is cylindrical in shape with an opening at one end
thereof, said cartridge having a ram positioned within
said cylindrical shape remote from said opening, being
capable of displacement toward said opening to provide
pres-~ure. Said ram operates as a plunger for exerting
said pre~sure
This in~ention is al30 directed to a method for
treating agricultural crops comprising the steps of:
WO~3/12652 2 ~ 2 6 31 ?~ PCT/US92/10556
pro~iding a source of crop protection product in an
extrudable form, forcing a measured amount of crop
protection product from said source into a mixing zone,
introducing a liquid carrier medium into said mixing
zone, shearing the crop protection product together
with the liquid carrier medium in said mixing zone to
disperse said crop protection product within said
liquid carrier medium in said mixing zone, and spraying
the r~sulting mixture as it is formed onto the
agricultural crop.
The injection method and apparatus proYided by the
present invention offers advan~ages for applying crop
protection product in mediums such as gels and pas~es.
These forms of the crop protection product are
extrudable from the outlet opening of the container
means, in the sense that if the container means were
not connected ~o the interconnection means, the
extruded crop protection product would tend to maintain -
its extrudate shape without external assistance. This -
20 enables the crop protection product to be suppl~ed to -~
the application site in concentrated form without ;~
tendency to phase separate in said con~ainer or to leak
from the container in which it is ~upplied. The
invention u~es a design whereby all the crop protection
product, and some or all of a carrier medium, is
sxposed to an energy intense zone ~shear zone~ so that
su~ficient mechanical energy is imparted to the product
to insure dispersion into the carrier madium.
After exiting the shear zone, this dispers2d crop
protection product is comparable to crop protection
product in traditional solutions. Other application
ds~ices discloYed in the art fail to accomplish this
result. -
'~
WO93~12SS~ -~ P~T/US92/10~56
2~2S~2 -
BRIEF DES~RI~ION OF D~ ~RAWING~
Other features and advantages of the present
invention will become more fully apparent from the
following detailed description of the appended claims
and the accompanying drawings. Figure 1 is a schematic
cross-~ec~ional side view of apparatus according to the
invention. Figure 2 is a schematic cros~-sectional ~-
side view of apparatus with a plurality of containers,
according to the invention.
~ G~
The advantages offered by the no~el gelled-paste
compositions herein disclosed ars both functionally and
en~ironmentally attractive rela~ive to other
traditional product forms such as liquids, suspensions,
granules and powders. The gelled~paste product form
described by the present invention reduces risk of
point source contamination and user exposure associated
with pouring and handling of agricultural products. It
is also non-dusty and spill resistant and offers
improved shelf stability over traditional aqueous
suspensions, in that the disper~ed solid particulates
are locked-up in a gel matrix and not able to settle,
remaining uniform in active concentration throughout
the container during storage.
Preferred compositions of the invention are:
~1) Compositions wherein the weight psrcent of
the components are: 10-50~ of a sulfonylurea herbicide
and optionally, at least one additional agricultural
pesticide; 5-40% of an agriculturally suitable salt of
a carboxylic or inorganic acid; 0.5-10% of a water-
soluble or water-swellable synthetic, sémisynthetic or
biological polymer(s); and 1-10% of a dispersant.
(2) Compositions of Preferred 1 wherein the
weight percent of the components are: 10-40% of a
sulfonylursa herbicide and optionally, at least one
.... . . . .. . . .. . . . .. . ...
WO93/12652 2 1 2. 6 3 1 2 PCT/U~92~10556
additional agricultural pesticide; 5-25% of an
agriculturally suitable salt of a carboxylic or
inorganic acid; 0.5-5~ of a water-soluble or water-
swellable synthetic, semisynthetic or biological
polymer; and 1-5% of a dispersant.
(3) Compositions of Preferred 2 wherein the
weight percent of the components are: 20-40% of a
sulfonylurea herbicîde and optionally, at least one
additional agricultural pesticide; lQ-25~ of an
agriculturally suitable salt of a carboxylic or
inorganic acid; 0.5-2-~ of a water-soluble or water-
swellable synthetic, semisynthetic or biological
polymer; and 1-2% of a dispersant. `
(4) Compositions of Preferred 3 wherein the
15 water-soluble or water-swellable s~nthetic, -~
semisynthetic or biological polymer is 3elected from
the group consisting of alginates, alkali metal
alginatesl acrylic and methacrylic acids, acrylamides,
ioto lambda carrageenans, cellulo-Qe gums and their
20 derivati~es, N-vinyl-2-pyrrolidinone, starches and -~
their deri~atives, and xanthan gums.
(5) Compositions of Preferred 4 wherein the
water-soluble or water-swellable synthetic,
semisynthetic or biological polymer is selected from
the group consisting of alginates, alkali metal
alginates, acrylic and methacrylic acids, acrylamides,
ioto lambda carrageenans, N-vinyl-2-pyrrolidinons,
aluminum or calcium cro s-linked carboxymethyl
celluloQe, and starches and their derivatives.
(6) Compositions of Preferred 4 wherein ~he
cellulose i~ carboxymethyl cellulo e.
(7) Compositions of Preferred 4 wherein the
cellulose is hydroxyethyl cellulose.
W093~1265~ ` PCT/US92/~56
21.~6~12
8 :
(8) Compositions of Preferred 5 wherain the ~;;
cellulose is an aluminum cross-linked carboxyme~hyl
cellulose.
(9) Compositions of Preferred 5 wherein the
cellulose is a calcium cross-linked carboxymethyl
cellulose.
(10) Compositions of Preferred 4 wherein the
starch is derivatizsd with a synthetic acrylamide and
sodium or potassium acrylate polymer.
10(11) Co~positions of Preferred 4 wherein the
polymer is xanthan gum.
(12) Compo~itions of Preferred 4 wherein the
sulfonylurea herbicide is selected from the group:
chlorsulfuron; sulfometuron methyl; chlorimuron methyl;
metsulfuron methyl; methyl 2-[~[[(4,6-dimethoxy-2-
pyrimidinyl3amino]-carbonyl]amino]sulfonyl3-6-
(trifluoromethyl)-3-pyridinecarboxylate; ethamet-
sulfuron methyl; triasulfuron; ethyl 5-~[[(4,6-
dimethoxy-2-pyrimidinyl)amino]carbonyllamino~sulfonyl]-
1-methyl-1~-pyrazole-4-carboxylate; N-~ ,6-dimethoxy-
2-pyrimidinylamino]carbonyl]-3-(ethyl.~ulfonyl)-2-
pyridinesulfonamide; thifensulfuron methyl; tribenuron
methyl; bensulfuron methyl; nicosulfuron; and methyl
2-~[~[~4,6-bis(difluoromethoxy-2-pyrimidinyl~amino]-
carbonyl]amino]su~fonyl]benzoate.
(13~ The process wherein the gelled-paste is
comprised of, in weight percent based on total
formulation weight:
~a) one or a mixture of ~ulfonylurea in the
amount of 1-60% of active ingredi~nt,
. (b) one or a mixture of salts of a
carboxylic or inorganic acid, in the amount of 1-40%
pro~ided that the ~olubility of carboxylic or inorganic
acid salts in water at 5C and a pH of about 6-10 is
graater than or aqual to 3~ and further provided that
wo g3/.2~52 2 ~ ~. 6 3 ~ ~ PCT/US92/10556
9 .,
the pH of a 0.1 molar solution of the carboxylic or
inorganic acid salt is between 6 and 10,
(c~ one or a mix~ure of water-soluble or
water-swellable synthetic, semisynthetic or biological
polymers in the amount of 0.5-20%,
(d) 0-10% of a dispersant, and
~ e) an effective amount of an aqueous
medium.
(14) The process of Preferred 13 wher~in said ~-
gelling agent is blended into the dispersion by the
stirring of said disper~ion at sufficiently low shear -
so tha~ said gelled-paste is not broken up as it is
formed.
~15) Compositions of Preferred ~3) wherein the
sulfonylurea herbicide and additional pesticide
component is selected from the group consi~ting of
nicosulfuron and bromoxynil, chlorimuron ethyl and
metsulfuron methyl, and metsulfuron methyl and 2,4-D.
The term " ulfonylurea herbicide" is meant to
include the entire cla3s of sulfonylurea herbicides,
that is tho~e compounds containing the following and
any closely r~lated functionalities.
The preparation of sulfonylurea herbicides is
known in the art, e.g., see U.S. 4,127,405 and U.S.
4,169,719. Agriculturally suitable salts of
sulfonylureas are also useful herbicides and can be
prepared in a number of ways known in the art. For
example, metal salts can be made by treating
sul~onylureas with a 301ution of an alkali metal salt
ha~ing a sufficiently basic anion ~e.g., hydroxide,
, .. ,, ~ , . , ... . ,, ~ . ~
W093~2~52 - PCT/US92/1~55~
21%~31~ lo
alkoxide, carbonate or hydride). Ammonium and
substituted ammonium salts can also be made by similar
techniques Cation exchange to form the agriculturally
suitable sulfonylurea salt where the sulfonylurea acid
or salt is direc~ly treated with an aqueous solution
containing the cation to be exchanged is ~lso known in
the art. Cation exchange can also be effected by
passing an aqueous solution of ~he sulfonylurea salt
through a column packed with a cation exchange resin.
U.S. 4,936,900 teaches that stabilized aqueous
suspansions of compounds of sulfonylurea herbicide
acti~e ingredients can be prepared when the aqueous
suspending medium contains ammonium, sub-~tituted
ammonium or al~ali metal salts of a carboxylic acid or
an inorganic acid or mixtures of such salts provided
that the solubility of those salLs at pH 6-10 is
greater than or equal to 3% at 5C, and fur~her
provided tha~ ~he pH of a 0.1 molar aqueous solution of
the carboxylic or inorganic acid salt i5 between 6 and
10.
The salts which are preferred in the aqueous
medium are ammonium, substituted ammonium or alkali
metal salts of a carboxylic or an inorganic acid which
are soluble in water at 3% or more at 5C. The useful
concentration range is from 3% to the saturation point
at 5C. The prefsrred salts of the invention will
further possess a pH between 6 and 10 for a 0.1 molar
aqueous solution. Examples of these salts ar~
diammonium hydrogen phosphate, ammonium acetate,
lithium acetate, sodium thiocyanate, sodium ac~tate,
potassium acetate, or compatible mixtures thereof.
Diammonium hydrogen phosphate and sodium acetate are
preferred for compositions containing the ammonium and
sodium salts, respecti~ely, of the salts of the
sulfonylurea herbicide. The useful pH xange of these
WO93/126~2 2 ~ 3 1 2 ~CT~VS92~10556
11 `
compositions is ~-10 although 7-9 is-preferred. In
most cases, the salts de3cribed above automatically
produce a formulation with the desired pH. The anion
of the carboxylic or inorganio acid salt may act as an
acid acceptor and generate in situ the salt of thP
sulfonylurea herbicide from its corresponding conjugate -
acid.
The formulations of this inven~ion contain about 1
to ~0~ (preferably 10 to 40%) of the compounds of the
sulfonylurea herbicide active ingredients ~uspended in
an aqueous solution which contains from 3% to the salt
saturation amounts of an agriculturally suitable salt
of a carboxylic or an inorganic acid or mixtures
thereof as described above. Preferred concentrations
of these carboxylic or inorganic acid salts are in the
range of about 10-40% in the aqueous phase.
U.S. 4,936,900 disclo-~es the need for di~persants
to insure proper wetting and disper3ing
characteristics. The term "dispersant" is meant to
20 include common wetting and dispersing agents ~uch a-~ -
trimethylnonyl polyethylene glycol ether, ~odium
alkylnaphthalenesulfonates, sodium ;
.- alkylbenzenesulfonates, sodium dioctyl sulfosuccinate,
sodium dodecyl sulfate, the ammonium and sodium salts
of ligno~ulfonic acid and formaldehyde condensates of
naphthalenesulfonic acid.
The pre~ent invention incorporates the use of at
least one synthetic, semisynthstic or biological
polymer which is water-soluble or watar-swellabler
3~ which will retain its u~ility as a gelling agent in the
presence of ammonium or alkali metal salts of a
carboxylic or an inorganic acid allowing the
consistency of the aqueous sulfonylurea or
agriculturally suitable ~alt -~uspension ~o be altered
to that of a gelled-paste without a detrimental effect
W~9~/12652 PCT/US9~/105~6
212 6~ 1 2 12 ^
on the chemical stability of the sulfonylurea or its
agriculturally suitable salt, as determined by
comparison to a reference sample which does not contain
polymer.
In this invantion the term "water-soluble or
water-swellable synthetic, semisynthetic or biological
polymer" includes macromolecules which form hydrogels,
have weight average molecular weights ranging from
se~eral thousands to millions, and retain their
functionality in the presence of carboxylic ~r
inorganic acid salt or mixtures thereof.
Examples of polymers which can form hydrogels
include, but are not limited to, alginates and alkali
metal alginates, acrylic and methacrylic acids,
glycerol methacrylates, acrylamides r ioto and lambda
carrageenans, cellu}ose gums and their deri~ati~es
~e.g., carboxymethyl cellulose and hydroxyethyl -~
cellulose), poly(CHEM~), copolymers of N-vinyl-2-
pyrrolidinone, starches and their deri~atives (e.g.,
naturally occurring starch derivatives with a synthetic
acrylamide and sodium or potassium acrylate polymer),
and xanthan gums.
An additional requirement for the selection of
polymers which are suitable as gelling agents in this
invention is chemical and physical compatibility with
the sulfonylurea present in solution and as par~icles ;
of the paste. The identification o~ polymers with
suitable characteristics is detailed below. Polymers
which are not suitable for use in this pre~ent
invention are polymers which do not form hydrogels in
salt environments or which chemically destabilize
sulfonylureas.
For many polymers the adverse ef~ect o* salts on ~
their ability to form gels in aqueous solutions is `-
known in the art. Product literature avail ble from
W093~12652 2 1 ~ 3 1 2 PCT/US92~10556
.
13
most vendors of polymeric materials and the following -
reference contain such information, ~andbook of Water
Soluble Gums and Resins, Robert L. D~idson, Ed.
McGraw-Hill, 1908.
The ~elled-pa-~tes of this in~ention can also be
appled directly to the locus to be protected without
prior dissolution or dispersion into a spray solu~ion.
For example, a spot gun may be used to directly apply
the gelled-pa3te at the base of a tree of into the
soil.
The gelled-pastes of this invention do ~ot
compromise performance when u3ed with mechanical mixing
devices which i~sure incorporation.of the gelled-paste
into a spray solution. When finely disper~ed, these
compositions can be sprayed through conventional spray
nozzles in which 50 mech scrsens precede each nozzle to
protect it from blockage. When disper~ed the gelled-
pastes of this invention have been shown ~o be as
biologically effecti~e as the control dispersion (no
polymer3 in greenhouse testing.
The gelled-pastes o~ this invention can also be
applied directly to the locus to be protected without
prior dissolution or dispersion into a spray solution.
For example, a spot gun may be used to directly apply
the gelled-paste at the base of a tree or into the
soil.
The gelled-pastes detailed in this invention are
obtained by the combination of the techniques detailed
in U.S. 4,936,900 with the selection of appropriate
water-solubie or water-swellable synthetic,
semisynthetic of biological polymer(s). In accordance
with the process of ~.S. 4,936,900, it is known in the
art th~t polymers (organic macromolecules), clays,
silicas and silicates can be u3ed, alone or in
W~3/12652 PCT/US92tlO556
2~ 631.~ 14
combination, as thickening or suspending agents for
aqueous suspensions.
In the agrichemical art, thickeners are used to
thicken agrichemical liquid formulations but still
S leave them pourable, so as to be adaptable for addition
to mixing tanks and dispersible therein when mixed with
water.
It is also known in the art ~hat polymer
thickeners are more effective thickening agents than
are the inorganic thickeners, requiring O.Ol to 0.2
percent (polymer) V5. 0.5 to 5% ~inorganics) to achie~e
~he desirable antisettling characteris~ic associated
with thickened aqueous suspensions..
The pres~nt invention in~olves not only the
selection of certain polymers for gelling the herbicide
composition so as to render it nonflowable, but al~o
the selection of ~he use of such polymer in a greater
amount than used as a thickener and incorporation into
the composition in a manner which permits the gellation
to occur.
The polymers useful in this invention retain their
identity as gelling agents in the presence of ~alt and ~:
sulfonylurea particulates while simu~taneously `~
preser~ing the chemical stabili~y of the sulfonylurea
25 or agriculturally suitable sulfonylurea salt. The :-
novel gelled-pastes of the present in~ention are rigid
and cannot readily be diluted into water unle~s they
are mechanically sheared first. -
Addition of the polymex at any step in the ..
preparation of the composition is acceptable, provided
the polymer does not degrade during the wet milling
step, per U.S 4,936,900. If stability to wet milling
is not known, the effect of mechanical energy on the
polymer in que~tion can be determined by comparing the
WO93/1~6~2 2 ~ 1 2 PCT/US~2/1~556
' :
properties of a formulation made by pre- and post- ~-
milling addition of the polymer.
By adjusting the amount of polymer, the desired
gelled-paste con~istency can ~e obtained. Optimiza~ion
of this consistency can be accomplished by ~isual
observation and experimental measurem~nt. Two measures -
of the gelled-paste strength ha~e been used to ~uantify
the extent of gellation, viscosity and yield stress
measurements. In the Examples of this invention, both -
the viscosity and yield stress were measured using a
rotational v~scometer. Standard instruments are
readily available from various companies, such as
Haake, Contraves, Carri-Med, Bohlin and Brookfield. -
Both the instrument and accompanying geometry (parallel
plate, cone and plate, concentric cylinder sample
compar~ments~ can be used to accurately mea ure yield
stress and ViSCQsity by one of the following
techniques.
Either a fixed shear rate can be imposed on a
sample and the resulting stress measured, or a
controlled stress can be imposed on a 3ample and the
resulting shear rate measured. Regardless of the
method chosen~ a plot of the shear rate vs. stre~s can
be constructed and analyzed, to extract the plastic
~5 viscosity and yield stress of the sample, by applying
the Bingham Equation. This is done by fitting the
linear portion of the data to the equation. The slope
of the plot gives the plastic viscosity of the sample
and the intercept of the plot gi~es its yield stress.
A more in-depth review of the art can be found in many
texts on viscometry, rheology or rheometry. The
ollowing references contain such in~ormation: 1)
K. Walters, "Rheometry: Industrial Applications",
Research Studies Press (1980), 2) P. Sherman,
"Industrial Rheology", Academic Press (1970), 3)
WO93/12652 - i PCT/US92/10~56
2 1 2 ~
16
T. C. Patton~ "Paint Flow and Pigment Dispersion",
Wiley (1979~. Geometric constants, equa~ions and
instrumentation to automate instrument operation and
calculation are routinely supplied with all of the -
5 instruments mentioned above. :~
In genexal, the plastic viscosity and yield stre~s
of a ge~led-pa~te will be higher than that of a
suspension which does not contain a gellant. Thus, the -
measurement of yield stress and plastic viscosity can
be used to evaluate the degree of gellation or the
strength of the gelled-paste under consideration.
In the instant invention, visual observation,
plastic viscosity, yield stress and chemical stability
of the active sulfsnylurea herbicide or its
agriculturally suitable salt wer~ uYed to establish
that a suitable polymer had been selected, i.e., one
which gave a physically suitable gelled-paste
composition in which the chemical s~ability of the
sulfonylurea or agriculturally suitable sulfonylurea
salt was not diminished relative to ~hat of the aqueous
high salt suspension which did not contain the polymer -~
used to form the gelled-paste. The aqueous high salt
suspension which did not contain the gellant is
rsferred to as the control or reference sample in the
Ex~mples which follow.
G. G. Ha~ley's, "The Condensed Chemical
Dictionary," 10th Edition, Van Nostrand Reinhold
Company, defines a gel as "a colloid in which the
dispersed pha-qe has combined with the continuous phase
to produce a viscous, jelly-like product." Consis~ent
with this definition, an aqueous suspension not
containing an effective "gellant" is thin and fluid-
like, and eventually phase separate on stsrage at
ambient temperature. In contrast, an effective gellant
WO93/1~6~ 2. ~`?. &~ ~ ?. PCT/U~92/~V556 ~
,,
17 ~;
produces a ~ombina~ion of continuous phase and
dispersed phaqe interaction(s) leading to a viscous, --
jelly-like product. -
For the purpose of physically characterizing the
aqueous suspen~ions, and the gelled-pastes of this
invention, the effectiveness of a given p~lymer(s) was
visually assessed by using one or more of the following
criteria:
i. Rigidity, reflected by the gelled-paste's
ability to re~ain a deformation over an ob~erved time
frame of several minutes, for example upon separating
~pulling apart) two plates between which a gelled-paste
of thickness about 1 mm has been placed, the gelled-
paste shows and retains a unique solid-like form and
resists flow under its own weight as evidenced by the
persistence of a macroscopic ~orm or "structure"
(ridges).
ii. Resiliency, elastic "jelly-like" or
"toothpaste-like" consistency, the la~ter being more
descriptive of a gel which con~ain~ ~u~pended
particles.
iii. Resistance to movemen~ (flow) as determined
.- by littla or no mo~ement of the sample on tilting.
iv. Little or no pha~e separation over time.
v. Requires vigorous mixing to disperse into ~-
aqusous media.
A more quantitative method by which the
effectiveness of a polymer is det~rmined is ~he
measurement of viscosity and yield stress. This
techni~ue was also used to characterize the gelled-
pastes of this instant invention and required that ~he
rheological responQe of the sample be evaluated by
conventional rotational rheometry technîques. For the
purpo3e o~ this invention, a controlled stre~
W~93/12652 2 1 2 6 3 ~ 2 PCT/US92~105~6 .
... .
,
18
rheometer equipped with a standard, calibrated, cone
and plate geometry was used.
For the liquid-like, con~rol dispersîons, a range
of stress from 0.1-10 Pa was applied to the sample in
20 logarithmic st~ps, from lowsst to highest, with each
stress allowed to act on the sample for 30 saconds
before the next higher stress was applied. The same
procedure was used for the gelled-pas~e samples with ~-
one exception, the applied stre~s range was shifted
from 10-100 Pa to accommodate the increased stiffness
of the gelled-paste samples. The Bingham Equation was
applied to each data set, as previously described to
calculate yield stre~s and plastic viscosity. -:
Chemical ~ Urements
Once an acceptable polymer was identified, based
on the physical characteristics described, the original
gelled-paste and control ~no gellant) samples were
stored ~ide-by-~ide in sealed containers for 3 weeks at
0-5-~C. Upon removal, both sample sets were assayed
for sulfonylurea or sulfonylursa salt content and the
re~ults compared to determine the chemical suitability
- of the polymer. ~:
The correct Qelection of polymer is determined as
follows. The gelled-paste is compared to a reference ::
sample, wherein the reference sample contains water in
place of polymer;
a) the polymer is selected by visual inspection,
in which the beneficial effect of the invention is
demonstrated by an increase in rigidity, consistency,
30 resiliency, resistance to flow, and reduced phase ;
~eparation relative to the reference, or
b) the polymer is selected by viscosity
measurement, in which the beneficial effect of the
invention is demonstrated by an increase in viscosity
. .
WO93/12652 2 1 2 6 3 1 2 PCT/U~9~/105~6
.
over that o~ the reference dispersion which does not -
contain a gellant, or
c) the polymer is selected by yield stress
measurement, in which the beneficial effect of the
invention is demonstrated by an increase in yield
stress over that of the control dispersion which does
not contain a gellant.
The gr~up of sulfonylureas selected to illustrate
the novel gelled-paste formulations of this invention
are listed below by their common name. For the purpo~e
of the following examples, these sulfonylureas will be
hereafter referred to by the compound numbers~
chlorsulfuron, II - met-~ulfuron methyl, III =
thifensulfuron methyl, and IV = tribenuron methyl.
The p~eparation of stable gelled-paste
compositions can be separated into two 3eparate steps~
formation of the dispersion, followed by the additio~
of the gelling agent ~3) .
A preferred technique for the preparation of
stabilized disper3ions is described in U.S. 4,936,900.
In accordance with this procedure the sulfonylurea is -~
~uspended in watsr and a dispersant, thickener or
suspending agent is added. The mixture is then treated
with a desired base such as ammonium or sodium
hydroxide t~ a pH of 6.0-lO.0, pre~era~ly 7.0-9.0, and
then treated with an insolubilizing salt, such as a
carboxylic ~r inorganic acid salt(s), with agitation.
The insolubilizing salt decreases the solubili~y of the
sulfonylurea causing the sulfonylurea to precipitate
out of solution. This method of preparation has been
adopted in the present invention. Since the dispersion
was to be gelled, the thickener was excluded from the
composition. All salts were added incrementally to the
neutralized conjugate acids in order to develop the
precipitated sulfonylurea and sulfonylurea salt slowly
WO93/12652 PCT/US92~105~6
212~312 ` `
and avoid the formation of a tacky solid or gum, per
U.S. 4,936,900. The resulting suspension was then
bead-milled to a particle size of 1-20 microns,
preferably 1-8 microns.
A gelling agent or mixture of gelling agents,
water soluble or water swellable synthetic,
semisynthetic or biological polymer(s), were added
after the milling step was completed to void the risk
of degradation of the polymer during a high shear
milling step.
The gelling agents selected to illustrate the
novel gelled-paste formulations of the instant
invention are listed below. Specific commercial
products from each class are referred to by name and
15 source. In the following Examplesf all polymers are -
referred to by c~mmercial or trade name.
Xanthan Gum - Kelzan~, a product of Kelco Corp.,
was selected to demonstrate ~he utility of water
soluble biopolymers/gums. ~
Modified Starch - SGP147~ ("Super Slurper"), a ;
produc~ of ~enkel Corp., was selected to demonstrate
the u~ility of water swellable starches.
Cellulose - CMC-7L~ and CMC-7M~, a product of
Hercules, Inc., low(L) and medium(M) molecular weight
carboxymethyl derivatives of cellulose, were salected
to demonstrate the utility of cellulosics.
Examples 1-10 illustrate the utility of the above
polymers with a variety of sulfonylurea actives, at a
sulfonylurea concentration of approximately 19-21% by
weight. Examples 11-14 illustrate the utility of the
invention at higher sulfonylurea content and under
conditions wherein the -qtabilizing salt level and
identity have been changed.
In all cases where a composition is not re~erred
to a~ a control it contains a gellant or gellant system
WO93/12652 2 ~ 2 ~ 3 ~ 2 P~T/US92/10556
21
and will be classified as a gelled-paste. In all the
Examples which follow, the gelled-pastes can be
visually described as being rigid and resilient,
exhibiting a range of alastic character and viscosities
which are consistently greater than that of the control
dispersion.
Com ~ ~n
~en~ntb~Wei~t)
~e~en~ Con~ol~ ~OD~OL~ ~Ll No.2
Compo~dl 20.2 20.2 20.2 20.2
s~umaky~ph~en~N~o~te 1.0 1.0 1.0 1.0
A~eousS0%S~umHy~n~ 4.5 4.5 4.5 4-5
S~um A~te(ADhy~n~s) 0.0 20.0 20.0 20.0
Water 74.3 ~.3 sæ3 52.4
Ge~gAgentX~n~um - 2.0
~9)
M~fiedS~h(Su~Slwp~) - - 1.9
The sodium alkylnaphthalenesulfonate was dissolved
in about 80-90% of the total water, at room
temperature, with stirring. Compound I was added
incrementally, in three equal portions, and allowed to
disperse well. The 50% aqueous sodi~m hydroxide
solution was then added slowly over a 15 min. period
with stirring to form the salt of Compound I. Where
anhydrous sodium acetate is indicated, it was added in
three steps, in a 1:1:2 ratio by weight. The additions
were made at 30, 45 and 55 min. during which time the
slurry was continually being stirred. The dispersion
was then bead-milled for 30 min. Upon completion, the
Z0 pH sf the milled dispersion was adjusted to 8.4 using a
dilute ~Cl so}ution and the gelling agent and/or water
were added to achieve the above statement of
composition. The final mixture was stirred un~il
~isually homogeneous.
WOg3/12652 PCT/US92/10556
~ 126312 2?
The yield s~ress and plastic ~iscosity of each
composition were measured as previously described. The
results are tabulated below.
Yield Stress Plastic Viscosity
!Pa~cala~
- Control A (No Salt~ <1 <l
Control B (No Gellant) 0.33 0.03 .
No. 1 ~el~an~ 250.0 331.0
No. 2 Super Slurper 40.6 0.65
To determine chemical stability and acceptability
of physical properties, all samples were aged at 45C
for 3 weeks. After aging, their visual appearance and
chemical properties were assessed and compared.
- Both aged and unaged control samples ~A and B)
settled leaving a brownish supernatan~ phase atop the
dispersion within a day, whereas, the gelled systems
showed little or no t~ndency to form a supernatant over
the three week per~od of the experiment. Greater than -
10% relative decomposition of Compound I occurred
during the 3 week, 45~C oven aging of Control A, due to
the absence of the stabilizing carboxylic or inorganic
acid salt. No detectable decomposition of active
ingredient occurred during 3 week storage at 45C in
the Control B sample which contained the stabilizing
sodium acetate carboxylic acid salt. Likewise, no
detectable decomposition was seen in sample No. 1
~Kelzan~) or No. 2 (Super Slurper). From these data
the ability to gel a dispersion of sulfonylur~a with a
polymer which is functional in high salt medium without
significant decomposition of the sulfonylurea active,
is demonstrated.
WO 93/12~52 2 ~ ~. 6 3 1~ ~ P~/VS9~/10556
23
E~PLE~ 3 TO 5
Composldol~
(Percent by Wei~ht) :
~rediçnts CQn~ o. 3 ~o.4
Compound I 18.7 18.û 18.4 17.8
sodiumallyl~aphthalenesulfonate 0.9 0.9 0.9 0.9
Aqueous 50% Sodium Hydro~de 4.1 4.0 4.0 3.9
Sodium Acetate (A~ydrous) ~8.4 17.8 18.1 17.6
Water 57.9 ~6A 54.~ 55.4
Gelling Agent CaIbo~nnethyl -- 2.9
CaIbo~ymethyl C~lulose (CMC-7L~) -- -- 3.8 3.8
Crosslinld~g Agen~ Aluminum -- -- -- 0.6
Acetate Monobasic
The compositions were processed pex Examples 1 and
2. Upon completion of the bead-milling step, the pH of
the milled disper~ion was adju~ted to 8.4 using a
dilute HCl solution~ The gelling agent was then added
followed by water and/or water plus the Aluminum
Acetate Monobasic, per the above statement of
composition. The final mixture was stirred until
visually homogenaous.
The yield stress and plastic visco~ity of earh
composition were measured as previously described. The
results are tabula~ed below.
Yield Stress Pla~tic Vlscoslty
~m ~Pascal~
Contrsl C (No Gellant)0 . l9 O . Ol
~o . 3 CMC-7~ 133 . 0 25 . 1
No. 4 CMC-7IAD 63 . 8 2 . O
No . 5 Cros~-linked CMC-7I~ 64 . 3 1. 2
,
To determine chemical stability and acceptability
of physical properties, all ~amples were aged at 4SC
for 3 weeks. After aging, their visual appearance and
WO931126~2 ~ 2 6 3 1 2 P~T/US92/10556
24
chemical properties were assesse~ and compared. The
control sample settled leaving a brownish supernatant
phase atop the dispersion within a day, whereas, the
gelled systems showed little or no tendency to form a -~
supernatant over the three week period of the
experiment. No decomposition of the acti~e was
detected in the control or gelled samples as a result
of the 45C oven aging. From ~hese data the ability to
gel a dispersion of sulfonylurea with a polymer which
10 is functional in high salt medium and which can be `
cross-linked to pro~ide grea~er gel strength without
significant decomposition of the sulfonylurea acti~e is
demonstrated.
EXAMPLE~
Compo~it~on :
(Percent b~ Wei~ht?
Compou~d II 21.0 21.0
sod~um alkylnaphthalene~ul~onate 1.O 1.O
Aqueous 50~ Sodium Hydroxide3.5 3.5
Sodium Acetate ~Anhydrous) 20.0 20.0
Water 54.4 50,7
Carboxymethyl Cellulose ~CMC-7~ 3.8
15The compositions were processed per Examples 1 and
2. Upon completion of the bead-milling step, the pH of `~
the milled dispersion was adjusted to 8.0 using a
dilute NaOH solution and the qelling agent and/or water
were added to achieve the above statement of
~0 composition. The final mixture was then stirred until
visually homogeneous. The yield stress and plastic
vi~cosity of each composition were measured as
previously described. The results are tabulated below.
W ~ 93/12652 ~ 1 2 S 3 ~ 2 PCT/VS92~10556
'
Yield Stress Plastic Vi~cosity
Syst~m ~Pascals) (Pa~G~L-secon~L
Control D~No Gellant) 0.18 0.01
No. 6 CMC-7L~ 62.5 1.9
To determine chemical stability and acceptability
of physical properties, all samples were aged at 45C
for 3 weeks. After aging, their visual appearance and
chemica~ properties were assessad and compared. The
control sample settled leaving a brow~ish supernatant
phase atop the dispersion within a day, whereas, the
gelled systems showed little or no tendency to form a
supernatant o~er the ~hree week period of the
experiment. Nine percent relative decomposition of the
active was measured in the control sa~ple after 3 weeks
storage at 45C. Less than 4% relati~e decomposition
was measured in the CMC-7L~ gellsd-pa~te stored a~ 45C
for 3 weeks. From these data the ability to gel a
dispersion of ~ulfonylurea with a polymer which is
15 functional in high salt medium without significant
decomposition of the sulfonylurea active is
demonstrated.
EX~MPLES 7 T0 8
Composltion
(Percent by Wei~ht)
:9~ls~L5 SÇ~9L_~ No 7 NQ_ a
Compound III 21.0 2~.0 21.0
90dium alkylnaphthalene~u}fonate 1.0 1.0 1.0
Aqueous 50% Sodium Hydroxide4.1 3.5 3.5
Sodium Acetate (Anhydrous) 20.0 20.0 20.0
Water 53.9 52.5 49.5
Gelling Agent Xanthan Gum -- 2.0 --
(Kelzan~)
Carboxymethyl Cellulose (CMC-7~ 3.8
Cros31inklng Agent - Aluminum -- -- 0.6
Acetate Monobasic
WO93/126~2 PCT/VS92/10~56
2~ 26~12 26
The compositions were processed per Examples 1 and
2. Upon completion of the bead-milling step, the pH of
the milled dispersion was found to be 8.1 and was not
further adjusted. The gelling agent waQ added,
followed by water and/or water plus the Aluminum
Acetate Monobasic, per ~he above statement of
composition. The final mixture was stirred until
visually homogeneous.
The yield stress and plastic viscosity of each
composition were measured as pre~iously described. The
results are tabulated below. -
Yield Str~s Plastic Vi~cosity
System tP~cal~ lPasGa~-S~conds~
Control E (No Gellant~ 0 . 06 0 . 03
No. 7 Kelzan~D 81. 0 6 .1
No. 8 Cro~-linked C~C-7L~) 96.5 2.2 :
To determine chemical stability and acceptability
of physical properti~s, all samples were aged at 45C
for 3 weeks. After aging, their visual appearance and
chemical properties were ass~ssed and compared. The
control sample settled within a day whereas, the gelled
systems showed little or no tendency to form a
supernatant over the three week period of the
experiment. Less than 4% relative decomposition of
active was found in all samples after 3 week aging at
45C. From these data the ability to gel a dispersion
of sulfonylurea with a polymer which is fu~ctional in
high salt medium and which can be cross-linked to
provide greater gel strength without significant
decomposition of the sulfonylurea active is
demonstrated.
WO93/12652 ~ l 2 6 ~ ~ ~ PCT/US~2/1055
27
Compo~ition
~Percent ~y Weiqht~
In~ledient~ 2L_~ ~Q__~ NQ. lQ
Compound IV 21.0 21.0 21.0
sodium al~ylnaphthalene~ul~onate 1.0 1.0 1.0
Aqueous 50% Sodium Hydroxide 0.3 0.3 0-3
Sodium Acetate (Anhydrou~) 20.0 20.0 20.0
Water
Gelliny Agent M~dlfied Starch -- 3.8 --
~Super Slurper~
Carboxymethyl Cellulo3e (CMC-7~ -- 3.8
The compositions were processed per Examples 1 and
2~ The pH of the bead-milled dispersion was then
adjusted to 8.2 with a dilute solution of sodium ~~
hydroxide and ths gelling agent and/or water were added
to achieve the above statement of comp~sition. The
final mixture was stirred until visually homogeneous.
The yield stress and plastic viscosity of each
composition were measured as previously described. The
results are tabulated below.
Ylald Stre33Pla3tic Vi~c08ity
~y~m ~Pa~cal~ lPa~al-Second~)
Control F ~No Gellant) 0.06 0.02 ~
No. 9 Super Slurper 76.4 63.0 :
No. 10 CMC-7~ 63.9 1.2 ~
`~.
To determine chemical stability and acceptability
of physical properties, all samples were aged at 45C
~or 3 weeks, After aging, their visual appearance and
chemical properties were assessed and comparad. The
control sample set~led leaving a brownish supernatant
phase atop the dispersion within a day whereas, the
gelled systems showed little or no tendency to fonm a
WO93/l2652 PCT/US92/10556
~2S3~2
2~
supernatant over the three week period of the
experiment. Less than 5~ relative decomposition of
active occurred in the control sample, while 14-29~
re~ativ2 decomposition was found in the gslled samples
after storage for 3 weeks at 45C.
The increased decomposition rate for the gelled-
pastes of Compound IV over that of ~he control sample
is characteristic of the enhanced instability of
Compound IV active which is easily decomposed by trace
nucleophi~ic impurities such as those which could enter
into a gelled-paste through the addition of the
polymer.
~LES 11 TO 12
Composit~on
~Percent bY Wei~h~)
In~rçdien~s ~Q~¢~QL Q ~Q__11No. 12
Compound I 41.0 41.0 41.0
sodium al~ylnaphthalenesulfonate 2.0 2.0 2.0
Aqueous 50% Sodium Hydsoxide 8.5 8.5 8.5
Sodium Acetate (Anhydrou~) 10.0 10.0 10.0
Water 38.5 3B.0 37.5
Gelling Agent Xanthan Gum -- 0.5 --
- (K~lzan~) :
~o~ified Starch (Super Slurper) ~ 1.0
Using Compound I at about 40% active, Examples 11
and 12 represent hiqher active ingredient levPls than
thus far ex~mplified. The sodium acetate content has
also been dropped from 20% to 10~ to accommodate the
increa~ed active content.
The compositions were processed per Examples 1 and
Z. The pH of the bead-milled dispPrsion was then
adjuQted to 7.5 with a dilute -QolUtion of sodium
hydroY.ide and the gelling aqent and/or water were added
to achieve the above statement of composition. The
final mixture was stirred until visually homogeneous.
WO93/1~652 2 ~ 2 6 3 1.~ P~T/US92/10~5
29
The yield stress and plastic viscosity of each
composition were measured as previously described. The
results are tabulated below.
Yield StrassPla~tic Viscosity
~y~m ( Pa~ca I ~ ) IPa~cal-~cond~
Control G (No Gellant)1.3 0.33
No. 11 Kelzan~ 3~.~ 0.82
No. 12 Super Slurper 29.4 0.78
To determine chemical stability and acceptability
of physical properties, all samples were aged at 45C
for 3 weeks. After aging, their visual appearance and `
chemical properties were assessed and compared to the ~:
control. The control sample settled leaving a brownish
supernatant phase atop the dispersion within a few
10 days, whereas, the gelled systems showed little or no ~:~
tendency to form a supernatant over the three week
period of the experiment. ~ess than 3~ rel~tive -.
decomposition of active occurred in the control and
gellad samples, after 3 week aging at 4~C. From thase
15 data the ability to gel a 40% active dispersion of :~
sulfonylurea with a polymer which is functional in high
salt medium and which does not destabilize the .`
su~fonylurea active of interest, even in a gelled-paste
in which the sodium acetate stabilizing salt percentage
is reduced to 10%, is demonstrated.
,, . . .. ,, , ... , . ~ . . . .
WO~3/12652 PCT/US9~/10556
2126312 30
XAMPLE~ 13 T~ 14
Composltion
~Percent by Wa1qht)
In~re~ient~ Control H No~ 13 ~Q~
Compound II 41.1 41.1 41.1
sodium alkylnaphthalene~ulfonate 2.0 2.0 2.0
Aqueous 50% Sodium Hydro~ide 8.1 8.1 8.1
Sodium Acetate ~Anhydrous)10.0 10.0 10.0
Water 48.8 46.8 44.9
Gelling Agent Xanthan Gum -- 2.0 --
~Kelzan~)
Modified Starch (SUPBr S}urp~r) -- -- 3.9
Using Compound II at about 40%.active ingredient,
Ex~mples 13 and 14 represent higher active ingredient
levels than thus far exemplified. The sodium acetate
conten~ was also dropped from 20% to 10%, absolute, to
accommodate the incxea~ed active content. The
compositions were proce~sed per Examples 1 and 2. The
dispersion was bead-milled for approximately 30 min.
The pH of the milled dispersion was then adjust~d to
8.3 with a dilute solution of sodium hydrQxide and the
gelling agent and/or water were ~dded to achieve the
above statement of composition. The final mixture was
stirred until visually homogeneous.
The yield stress and plas~ic viscosity of each
15 composition was not measured. However, the expected '
range is given in the following table. -~
Yield StressPlastic Vlsco~ity
~m ~Pa3cals) (Pa3$al-S~çQn~
Control H (No Gellant) 2 - 5 0.2 - 0.5
No. 13 Kelza~ 50 - 500 10 - 800
No. 14 Super Slurper50 - 300 10 - 2000
WO93/12652 ~ 3 1 2 PCT/US92/10556
.
31
To determine chemical stability and acceptability
of physical properties, all samples were aged at 45C
for 3 weeks. After aging, their visual appearance and
chemical properties were assessed and compared to the
control. The control sample settled leaving a brownish
supernatan~ phase atop the dispersion within a few
days, whereas, the gelled systems showed little or no
tendency to form a supernatant over the three week
period of the experiment. Less than 2% relative
decomposition of active occurred in the control and
gelled samplesl during 3 week aging at 45C. From these
data the ability to gel a dispersion of sulfonylurea
with a polymer which is functional in high salt medium
without decomposing the su}fonylurea active is -
demonstrated.
The above Examples are presented to illustrate,
but in no way limit, the compositions of the present
invention. :-
The direct injection of crop prot ction products
is important in that it enables use of concentrated
crop protection products without ha~ing to dilute the
- crop protection products in a large spray tank. This
avoids contaminating a spray tank and, thereby, greatly
reduces the production of waste from the residue of
diluted crop protection products. Also, existing
systems have limited viscosity and other physical
property ranges due to a lack of an appropriate sys~em
component design ~Ghate, S. R. and Phatak, S. C.,
American Society of Agricultural Engineers paper
#901056, 1990 International Meeting, Columbus, Ohio,
Reichard, D. L. and Ladd, T. L., Transactions o~ the
American Society of Agricultural Engineer~ 1983, 26(3):
683-686). The known systems are limited ~o traditional
agricultural product forms (solutions, emulsifiable
concentrates, wettable powders and dry flowables) that
WO93/1265~ 1 2 PCT/US~2/10~6
are prepared by mechanical ~milling, stirring) and
chemical (formulation) means, to insure that the active
ingredient(s) disperses or dissolves into the carrier
medium when exposed to traditional low intensity tank
mix agitation and/or sparging. These products are
dissolved or mixed in contact with secondary fluids
such as water and oils, or a mixture thereof, the
carriers used to transfer the dispersed active ~-
ingredients through the spray machine, to a target.
These limitations are due to the limited range of
physical properties which the dispersing mechanisms can
handle. `
The prior art requires that crop protection
products be readily soluble and/or dispersible in
water, emulsions, or oil as a bulk carrier in a two-
fluid system. This requirement prohibits direct
injection of many useful crop protection products that
are not readily soluble or disparsible. This invention
provides a new and improved method and apparatus for
the direct injection of highly viscous and/or insoluble
crop protection products.
In accordance with the invention, and as shown in
Figure l and Figure 2, the apparatus 5 generally
includes displacement means lO, container means 15,
manifold 25, solenoid gate 30, mixing ch~mber 35, and
shearing means 40. A quick connect sealing means 20 is
mounted between container means 15 and interconnecting
means 21. Said quick connect ~ealing means is depicted
in a disconnected position for clarity in Figure l.
Container means 15, has an opening at its front
end 16 and optionally at its rear end 17, through which
the crop protection product can be loaded into the
container means. Application of pressure to the crop
protection product within container means 15 dispenses
it from said container means 15 through said front end
WO93~12652 ~ ~ 2 fi ~ ~ ~ PCT/US92/1~556
33
opening andr in turn, through said quick connect -
sealing means 20 and manifold 25 to the inlet opening
22 of said mixing chamber 35 through interconnecting
means 21 at a uniform or variable rate, depending on
control desired, as positive pressure is applied to
container means 15. Container means 15 may take :~
various sizes and shapes which will allow container
means 15 to be sealed so as to be internally
pressuri~able by internal or external means. Container
means 15 may itself contain the crop protection product
or may ser~e as a holder within which a replaceable
secondary container or cartridge 7 holding crop
protection product is placed.
Container means 15 is adapted by conventional
means to be readily replaceable by different containers
to thereby enable apparatus 5 to readily dispense a
variety of crop protection products with minimal delay
due to switching of crop prstection products.
Container m2ans 15 may also comprise a plurality of
like or s?milar containers for housing crop protection
products mounted by conventional means on a container
support. Each of the plurality of container~ may house
a different crop protection product. Container means
15, when removed from apparatus 5, may be used for
storing crop protection products.
Container means 15 is u~ed with a pressuxe means,
10, for applying pressure to the interior of container
means 15 to transfer crop protection product from
container means 15 to manifold 25 and into mixing
chamber 35. Also preferab~y, container means 15 is in
the form of a hollow cylinder that can be pressurized
by pressure means 10 that i5 in the form of a piston
consisting of Rod 9 and a piston head 11 mounted on one ~-
end of the rod. Head ll is suitably dimensioned to
provide for substantially flush contact with the
WO93/12652 2 1 2 fi 3 1 ,~ PCT/US92/10556
34
interior walls of container msans 15 or of cartridge 7
when container means 15 is provided with a replaceable
cartridge 7.`
The interconnecting means 21 may utilize any - ~`
conventional means of connecting the container means 15
with the mixing chamber 35.
The preferred interconnecting means 21, attached
to the front end of container means 15 by means of a
quick connect seal 20, is comprised of a manifold 25
and a solenoid gate 30 at the downstream end of
interconnecting mean~ 21.
The solenoid gate 30, located down~tream of
mani~old 25 and upstream of mixing cha~ber 35, is quick
acting to shut on-off instantaneously on command. The
solenoid is indicated in the drawing by a gate 30 in
the closed on-off position. The manifold'~ 25 role in
this device is to facilitate the flow of ~aterial from
container means 15 to the solenoid gate 30. Thi~
device may be a single fitting with a s~ngle channel
for materials to flow through or a series of channels
for multiple materials to flow through simul~aneou~ly
to meet at or before the solenoid gate 30. The
solenoid gate 30 control~ the flow of product from the
end of one or more channels in manifold 25 to mixing
chamber 35. This solenoid gate 30 can be operated
manually, electrically or hydraulically. The preferred
solenoid gate 30 for this invention is electrically
operated.
The pressure means 10 is a de~ice for forcing
products from container means 15 by putting prassure on
the product. Displacement of the crop protection
product may be accomplished by any means that allows
~or di~pensing of substantially all of the crop
protection product in the container means at a uniform
and con~i3tent rate oYer a wide range of ambiont
W093/12652 2 1 2 6 ~ 1 2 PCT/US92/10556
- ':
environmental conditions utilizing a positive pressure
differential between the product in container means 15
and the mixing chamber 35. This may be accomplished
by, but is not limited to such means as the following
methods, mechanical linear actuator hydraulic pressure,
compressed air, vacuum, or positive displacemen~ pump.
The preferred pressure means 10 is a device
providing energy to posi~ively displace material by
means of a DC drive motor/electronic controller
actuating a linear ball screw mechanism. A piston
drive plate corresponding to piston head 11, attached
to the end of the srrew engages a piston plunger 9 to
dispense product from the container.. Mechanical
displacement of the drive plate toward the container
outlet results in a gi~en volume of product dispensed
for a given linear stroke. This results in linear
rela'ionship of consistently accurate feed rates
metered across the entire operating range of the drive
mo~or, i.e., equal ~olume dispenQed per shaft rotation,
independent of the physical properties of the product,
such as changes in viscosity. Displacement rates are
dependent on dimensions of the container means and gear
ratio of the linear ball scraw. Limit switche~ may be
employed to monitor and regulate ~inear stroke length.
The mixing chamber 35 allows for the primary
medium, crop protection product, in a form such as a -
gel or paste, introduced from the container means
through a first inlet opening 23, ~o be dispersed and
mixed with a secondary carrier medium, such as water
andtor vegetable oils, coming under pressure from a
source thereof (not shown) via 3econd inlet opening 22.
Thi3 mixing chamber 35 must be adaptable to the
manifold 25, solenoid gate 30 and to the shearing means
40 without leaking liquid when the secondary carrier
medium is flowing through the chamber under pressure.
WO93J12652 ` PCT~US9~/105~6
21~1S312
36
The mixing chamber 35 should be of sufficient size and
shape to accommodate flows of 0 to lO00 gals per minute
under pressures of 0 to 827.4 KPA. The mixing chamber
35 must be of a design so that all the secondary and
primary media experience the high shear zone of the
mixing chamber. The inlets and outlets of the mixing
chamber are sized so as to not restrict the flow
volume. Preferably the pressure on the secondary
liquid medium, supplied ~uch as by a pump (not shown)
which transfers this medium from its source to the
mixing chamber, also is sufficient for applying the
resultant mix~ure exiting the chamber via outlet
opening 24 to the agricultural crop preferably as a
spray. -
The preferred mixing chamber 35 i5 a pressurized
vessel that houses a shearing means 40 for
homogeneously dispersing crop protection product as i~
is dispensed from container means 15 with t~e ~econdary
liquid medium. The crop protection product meets with -
the carrier medium ju3t prior to entering the shear
zone of the mixing chamber 35, which zone is defined by
the shearing means 40. Overall mixing chamber 35
dimensions are such that a minimum of residence time
for the mixture is required prior to exiting the outlet
opening 24. The mixing chamber 35 preferably comprises
two halves mounted directly to a DC motor drive (not
shown), for shearing means 40, to a position within the
chamber and disassembles to facilitate maintenance of
the internal components.
The shearing means 40 provides for the
instantaneous and homogeneous dispersion of the primary
material with the secondary medium or carrier. The
preferred device consists of a stationary housing, a
rotating blade(s) 42 po~itioned within said hou~ing,
3S said blade(s) having a close tolerance to said housing.
~0~3/l2652 ~ S 3 1 2 PCT/USg2/1~56
.. :
There are several conventional shearing de~ices. In
the preferred de~ice, the point at which the dispersion
exits (outlet opening ~4) is located in such an
- orientation within the shearing zone so materi l is
sheared as the flow exits the rotating blade 42 and
housing interface.
Suitable crop protec~ion products for use with
this in~ention are selected ~rom the group consisting
of herbicides, fungicides, insecticides, acaricides,
nematocides, miticides, virusides, algicides,
bactericides, and plant growth regulants, and their
agriculturally suitable salts. These products can be
made into pastes by addition of thickening agents to
dispersions or solutions thereof. The pastes can be ~-~
made into gels by addition of gelling agents, such as
gums, thereto. Carrier medium useful in this invention
include water and/or vegetable oils. Preferably the
carrier medium is aqueous. ;~
GENER~L PRO~EDURE
The crop protection product can be in the form of
a closed capsule or cartridge. Tha user loads the
cartridge into the container means 15. The user th~n
sets a controller to control the rate of di~pensing of
crop protection product by positive pressure at a -~
setting based on a unit volume/unit time calculation
according to the specifications of the crop protection -
product to be u~ed. The crop protection product is
intrcduced into the mixing chamber 35 and the correct
dosage is instantaneously and homogeneously mixed with
the secondary medium by the sheaxing means and sent
through outlet opening 24 to nozzles to the target
agricultural crop. The housing of shearing means 40
contains one or more exit slots 41 to permit the
dispersed crop protection product to flow from shearing
means 40 and exit through outlet opening 24 of the
WO93/12652 PCT/US92/10556
~12~12 38
mixing chamber 35. Since the crop protection product
is instantaneously mixed, the apparatus can be located
anywhere downstream of any spray equipment's main tank
as convenient and appropriate for installation and the
5 requirements of the installer/user, The preferred ~
location is on the main boom line after the pump and ~,
bypass line and before the split to auxiliary boom
lines. It is preferable that ~he apparatus be as close
as possible to the nozzle in order to reduce
contamination of the equipment.
The cartridge is connected and sealed by the quick
connect sealing means at the tip of the cartridge to
the solenoid gate. As the crop prote,ction product
moves through an electronic solenoid gate wh~ch
controls the flow of material into the mi~ing chamber,
it comes in contact with the secondary carrier medium.
The crop protection product and carrier medium flowing
under pressure mix through the shearing zone created by
a rotative blade, or other conventional shearing or
2Q mixing device. In the preferred invention there are
three blades 4~ turning at a high rate of revolutions
per minute that shear the material (crop protection
product plus carrier medium) between the blades and the
eight exit slots 41 that the materials pass through
be~ore exiting in a homogeneously mixed and finely
dispersed or solubiliæed form into the primary boom of
the spray system that the invention is attached to. An
electric 12 volt D.C. motor driv~s the blades of the
shearing means. The resulting mixture is forced out of
outlet opening 24 and then is relea~ed through the
spray nozzles where it is sprayed onto the target.
An example of a gel composition containing a crop
protection product to be used in this device is shown
below:
WO93/12652 ~ ~ hl 6 3 1 2 PCT/US92/10~6
39
Composition
(Perc~n~ ~y Wei~h~)
1. chlorsulfuron (herbicide) 18.4
2. sodium alkylnapthalenesulfonate 0.9
5 3. aqueous 50% sodium hydroxide 4.0
4. sodium acetate (anhydrous) 18.1 -
5. water 56.6-58.1
6. carboxymethyl cellulose (CMC-7L~) 0.5-2.0
The herbicide is mixed with ingredients 2-5
mentioned above under conditions of high shear as
described in U.S. 4,936,900 to form an aqueous
dispersion or paste of the chlorosulfuron, *ollowed by
addition of the CMC-7L~ under conditions of low shear
to form a gel of the paste having a viscosity in excess
of lOMM poise and possessing a yield stress of greater
than 1,000 Pa. This product is mixed and loaded into a
cartridge of a lengtX of 21.6 cm with a diameter of S.1
cm. A plastic plunger plate is fitted into tha open
end of th~ tube. The other end o~ the tube narrows to
an opening of 0.64 cm National Pipe Thread ;NPT) at
. which a quick connect coupler is attached.
- The cartridge is inserted into a cylinder sleeve
the quick connect coupler of which protrudes at one end
and which is closed OQ the other end to the closed gear
box. The gear box has a 30.5 cm long linear actuator
shaft which has 5.9 turns/cm. This shaft runs through
the gear box with a 5.4 cm round plate attached to the
end. This plate provides force against the plunger in
the cartridge to put force on the crop protection
product inside the cartridge. A 12 volt D.C. elactric
motor is connected by a coupler to the gear box to
drive the gears turning the shaft to provide the
forward movement of the actuator shaft engaging the
plunger. Mechanical displacement results in a given
WO93~12652 PCT/US92/10~5~
~1~6~12 40 ` ~
volume of product dispensed for a given linear stroke.
The rate at which materials forcPd through the solenoid
and into the mixing chamber at a continuous or variable
rate is dependent on the setting of a rheostat which - ~`
controls the amount of electric current the motor
receives thus determining the speed of its shaft
rotation. -~
Those skilled in the art, having the benefit of
the teachings of the present in~ention as hereinabove
set forth, ~an effect numerous modifications thereto.
These modifications are to be construed as being
encompassed wi~hin the scope of the present invention
as set forth in the appended Claims.
