U.S. patent application number 09/778280 was filed with the patent office on 2001-11-15 for microencapsulated clomazone in the presence of fat and resin.
Invention is credited to Becker, John M., Garcia, Hylsa E., Szamosi, Janos.
Application Number | 20010041659 09/778280 |
Document ID | / |
Family ID | 26823215 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010041659 |
Kind Code |
A1 |
Becker, John M. ; et
al. |
November 15, 2001 |
Microencapsulated clomazone in the presence of fat and resin
Abstract
The present invention provides an herbicidal formulation that is
composed of an aqueous liquid having suspended therein a multitude
of microcapsules having a capsule wall of a porous polymer
encapsulating a solution of clomazone, and suitable concentrations
of fat in the absence of a resin, or a resin in the absence of a
fat, or both fat and resin. Preferably, if included, the fat is at
least 95% saturated.
Inventors: |
Becker, John M.;
(Flemington, NJ) ; Szamosi, Janos; (Washington,
NJ) ; Garcia, Hylsa E.; (Elizabeth, NJ) |
Correspondence
Address: |
FMC Corporation
Patent Administrator
1735 Market Street
Philadelphia
PA
19103
US
|
Family ID: |
26823215 |
Appl. No.: |
09/778280 |
Filed: |
February 6, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09778280 |
Feb 6, 2001 |
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09521514 |
Mar 8, 2000 |
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6218339 |
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60125044 |
Mar 18, 1999 |
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Current U.S.
Class: |
504/140 |
Current CPC
Class: |
A01N 43/80 20130101;
A01N 43/80 20130101; A01N 25/28 20130101; A01N 25/04 20130101; A01N
43/80 20130101; A01N 2300/00 20130101 |
Class at
Publication: |
504/140 |
International
Class: |
A01N 043/02 |
Claims
What is claimed is:
1. A herbicidal formulation comprising microcapsules suspended in
an aqueous liquid, wherein the microcapsules comprise a porous
polymer wall, clomazone, and a fat or a resin.
2. The formulation of claim 1, wherein said clomazone and said fat
comprise a solution that is encapsulated by said microcapsules, and
from about 0.5% to about 12% by weight of said solution is said
fat.
3. The formulation of claim 2, wherein said fat is suet, lard, or
tallow.
4. The formulation of claim 3, wherein said fat is lard.
5. The formulation of claim 1, wherein said fat is at least about
95% saturated.
6. The formulation of claim 1, wherein said porous polymer wall
comprises from about 5% by weight to about 35% by weight of each
microcapsule.
7. The formulation of claim 1, wherein said porous polymer is a
polyurea.
8. The formulation of claim 7, wherein said polyurea is a
polymerization product of a polyfunctional isocyanate, resin, and a
polyfunctional amine.
9. The formulation of claim 8, wherein said resin is selected from
the group of ammonium hydroxide, sodium hydroxide, potassium
hydroxide, magnesium hydroxide, and the calcium hydroxide salts of
an anhydrous copolymerization product of styrene and maleic
anhydride; and the ammonium hydroxide, sodium hydroxide, potassium
hydroxide, magnesium hydroxide, and calcium hydroxide salts of a
half-acid/half-ester copolymerization product of styrene and maleic
anhydride.
10. The formulation of claim 9, wherein said cross-linking resin is
selected from said ammonium hydroxide and sodium hydroxide salts of
said anhydrous copolymerization product of styrene and maleic
anhydride.
11. The formulation of claim 1, wherein said microcapsules are
about 1 micron to about 100 microns in average diameter.
12. The formulation of claim 1, further comprising an emulsifier in
said aqueous liquid.
13. The formulation of claim 12, wherein said emulsifier is a
lignosulfonate or a resin.
14. The formulation of claim 1, further comprising an organic
solvent.
15. The formulation of claim 14, wherein said solvent is a
petroleum based mixture of C.sub.19-C.sub.15 aromatic hydrocarbons
with a flash point of about 95.degree. C.
16. The formulation of claim 1, further comprising a pH in the
range of about 5.0 to about 8.0.
17. A method for generating said formulation of claim 1, comprising
the following steps: (a) combining water and a lignosulfonate
surfactant; (b) adding a solution of clomazone, a polyisocyanate, a
highly saturated fat, wherein the highly saturated fat is at least
about 95% saturated, and optionally, an organic solvent; (c)
emulsifying the solution; and (d) adding a polyfunctional amine,
thereby generating microcapsules containing the solution of
clomazone and fat.
18. A method for generating said formulation of claim 1, comprising
the following steps: (a) combining water and a cross-linking resin
emulsifier; (b) adding a solution of clomazone, a polyisocyanate,
and optionally, a highly saturated fat wherein the highly saturated
fat is at least about 95% saturated, and an organic solvent. (c)
emulsifying the solution; and (d) adding a polyfunctional amine;
thereby generating microcapsules containing the solution of
clomazone, solvent, and optionally, fat.
19. A method of controlling vegetation comprising: (a) generating a
formulation in accordance with claim 17; and (b) spraying the
aqueous liquid to apply the clomazone in an herbicidally effective
amount to the surface of a selected plot containing vegetation to
be controlled, whereby vapor transfer of the sprayed herbicide to a
nearby plot containing crops is effectively suppressed without
substantial sacrifice of the herbicidal efficacy of the herbicide
in the plot to which the formulation is sprayed.
20. A method of controlling vegetation comprising: (a) generating a
formulation in accordance with claim 18; and (b) spraying the
aqueous liquid to apply the clomazone in an herbicidally effective
amount to the surface of a selected plot containing vegetation to
be controlled, whereby vapor transfer of the sprayed herbicide to a
nearby plot containing crops is effectively suppressed without
substantial sacrifice of the herbicidal efficacy of the herbicide
in the plot to which the formulation is sprayed.
Description
[0001] The present invention relates generally to the field of
herbicidal chemical compositions. In particular, the present
invention relates to novel compositions of a known herbicidal
compound, namely clomazone, designed to reduce clomazone's
characteristic volatility, thereby reducing risk of unintended
herbicidal activity when clomazone is applied.
[0002] Clomazone
(2-[(2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinon- e) is a
well-known herbicide commercially available for controlling many
broadleaf and most grass weeds, and has been found to have
selective characteristics making it particularly useful for the
control of weeds when growing soybean, cotton, sugarcane, rice,
tobacco, oilseed rape, vegetables and others. Clomazone can be
phytotoxic to some non-targeted crops and naturally occurring plant
species when applied to control undesired vegetation. Contact of
clomazone with such unintended crops is the result of vapor
transfer of the clomazone to sensitive species growing in adjacent
areas.
[0003] Although clomazone can be, and is, sold with suitable label
instructions to prevent exposure to sensitive crops, measures that
will further decrease the exposure of the non-targeted crops to
clomazone without substantial diminution of herbicidal efficacy
against weeds will greatly expand the usefulness of clomazone and
thus result in lower overall costs.
[0004] Other microencapsulated formulations of clomazone exist that
are intended to control the volatile nature of the herbicide. See,
e.g., U.S. Pat. Nos. 5,597,780, 5,583,090, and 5,783,520.
Unfortunately, these formulations do not provide optimum herbicidal
efficacy when compared to commercially available clomazone 4
pound/gallon emulsifiable concentrate (4.0EC) formulation. Given
the commercial value of clomazone, improved formulations are
therefore needed.
SUMMARY OF THE INVENTION
[0005] The present invention is directed to herbicidal formulations
comprising microcapsules suspended in an aqueous liquid medium,
wherein the microcapsules comprise a porous polymer wall,
clomazone, and a fat, or resin. Different embodiments of the
present invention include suitable concentrations of fat in the
absence of resin, or resin in the absence of fat, or both fat and
resin. Preferably, if included, the fat is at least 95% saturated.
The present invention is also directed to said formulations wherein
the porous polymer wall is, in part, the reaction product of the
resin and a polyisocyanate. These formulations provide for the
application of clomazone to undesirable vegetation encountered in
the cultivation of various plant species, particularly agronomic
crops, while minimizing off-target vapor transfer of the herbicide.
Accordingly, embodiments of the present invention provide
sufficient herbicidal efficacy with respect to unwanted vegetation,
yet avoid the aforementioned problems seen in currently available
formulations of clomazone.
[0006] In a first embodiment of the present invention there is
provided an aqueous dispersion of microcapsules containing a
herbicidally effective amount of clomazone in the presence of a
highly saturated fat that is at least about 95 % saturated.
[0007] In a second embodiment of the present invention there is
provided formulations containing a herbicidally effective amount of
clomazone wherein the microcapsule formed is, in part, the reaction
product of a styrene-maleic anhydride copolymer resin and a
polyfunctional polyisocyanate.
[0008] In a third embodiment of the present invention there is
provided formulations containing a herbicidally effective amount of
clomazone in the presence of a highly saturated fat that is at
least about 95% saturated, and wherein the microcapsule formed is,
in part, the reaction product of a styrene-maleic anhydride
copolymer resin and a polyfunctional polyisocyanate.
[0009] Preferably, in those formulations containing it, the fat is
at least about 98% saturated. Examples of such fats include,
without limitation, waxes, suet, lard or tallow. The encapsulant is
a porous condensate polymer of polyurea, polyamide or amide-urea
copolymer. To provide acceptable volatility control without
unacceptable sacrifice of herbicidal efficacy, the percentage of
polymer comprising the microcapsules ranges from about 5 percent to
about 35 percent by weight, preferably about 10 percent to about 25
percent by weight. Also the percentage of highly saturated fat of
the encapsulated material ranges from about 0.5 percent to about 12
percent by weight of the organic phase, preferably about 1 percent
to about 8 percent by weight, more preferably about 2 percent to
about 6 percent by weight.
[0010] The microcapsules of the present invention provide
volatility reduction of about 20-90 percent as compared with
clomazone prepared and applied from an emulsifiable concentrate,
which is commercially available. The microcapsules of the present
invention also provide increased herbicidal efficacy against
certain weed species from about one to about four times that of
known clomazone microcapsule formulations that are also
commercially available. Thus, the practice of the present
invention, among other things, enables one to apply clomazone to
the appropriate locus for control of weeds in crops while
eliminating or substantially diminishing the risk of clomazone
injury to plant species located in areas adjacent thereto without
the need to resort to expensive and time-consuming pre-plant
incorporation or special application procedures.
[0011] Definitions
[0012] The modifier "about" is used herein to indicate that certain
preferred operating ranges, such as ranges for molar ratios for
reactants, material amounts, and temperature, are not fixedly
determined. The meaning will often be apparent to one of ordinary
skill. For example, a recitation of a temperature range of about
120.degree. C. to about 135.degree. C. in reference to, for
example, a range of temperature for a chemical reaction would be
interpreted to include other like temperatures that can be expected
to favor a useful reaction rate for the reaction, such as
105.degree. C. or 150.degree. C. Where guidance from the experience
of those of ordinary skill is lacking, guidance from the context is
lacking, and where a more specific rule is not recited below, the
"about" range shall be not more than 10% of the absolute value of
an end point or 10% of the range recited, whichever is less.
[0013] The term "ambient temperature" refers to a temperature in
the range of about 20 .degree. C. to about 30.degree. C. As used
herein, the terms "crop", or "crops", "plant" or "plants" are one
and the same, and refer to plants of interest or plant products
derived thereof that are grown for ornamental, industrial or food
uses. The terms "weed" or "vegetation" are one and the same, and
refer to an unwanted plant or plants that are growing in a place or
in a manner that is detrimental to a plant or plants of interest.
The term "suet" refers to a hard fat found, for example, around the
kidneys and loins of beef and mutton, or cattle, from which tallow
is derived. The term "tallow" refers to a rendered fat from said
cattle. The term "lard" refers to a soft, solid or semi-solid fat
obtained by rendering fatty tissue of hogs. The term "CS" or "CS
formulation" refers to a microcapsule or capsule suspension
formulation of clomazone. The term, for example, "3.0 CS" or "3.0
CS formulation" refers to a microcapsule or capsule suspension
formulation of clomazone containing 3.0 pounds of clomazone/gallon
of finished formulation. The term "resin" refers to a chemical
polymer with a molecular weight of about 100,000 to about 400,000.
The term "cross-linking" refers to the chemical bonding between two
adjacent polymer chains.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The formulations of clomazone, in a first embodiment of the
present invention, provide an aqueous suspension of microcapsules
containing clomazone in combination with a highly saturated fat
that is at least about 95% saturated.
[0015] In a second embodiment of the present invention there is
provided formulations of clomazone wherein the microcapsule formed
is, in part, the reaction product of a suitable resin and a
polyfunctional polyisocyanate, wherein the resin is suitable if it
acts both as an emulsifier and a cross-linker with the
polyisocyanate. Preferred such resins include the copolymerization
products of styrene and maleic anhydride.
[0016] In a third embodiment of the present invention there is
provided formulations of clomazone in the presence of a highly
saturated fat that is at least about 95% saturated, and wherein the
microcapsule formed is, in part, the reaction product of a suitable
resin and a polyfunctional polyisocyanate, which functions as
described, supra.
[0017] A highly saturated fat that can be used in the context of
the present invention is one wherein at least about 95% of the
carbon-carbon bonds contained therein are single bonds; a preferred
highly saturated fat is one having at least about 98% single-bonded
carbon-carbon bonds; a more preferred highly saturated fat is one
having at least about 99% single bond carbon-carbon bonds.
Preferred highly saturated fats are commonly animal fats, such as,
without limitation, mutton suet, pork lard or beef tallow, or
combinations, or subfractions thereof. Such highly saturated fats
need not be of animal origin. For example, waxes of plant,
synthetic, and also animal origin can also be employed in the
context of the present invention, so long as the selected wax
exhibits the high saturation levels noted above.
[0018] Although the function of the fat used in the present
invention is not fully elucidated, it is believed that the high
degree of saturation of the fat used in the present invention, in
addition to contributing to the lowering of the natural volatility
of the clomazone, also contributes to the lowering of unintended
and detrimental reactions that would likely occur between
less-saturated solvents or fats and components of the wall of the
microcapsule. These unintended and detrimental reactions are
referred to as "fugitive reactions", and tend to disrupt the wall
structure by forming strands that necessitate an additional
filtration step in current clomazone formulation protocols.
Generally, the fat used in the context of the present invention is
a solid at room temperature, but dissolves in the presence of
clomazone, which is a liquid. Accordingly, the clomazone acts as a
solvent with the fat that is encased in the microcapsules of the
present invention.
[0019] The highly saturated fat as used in the context of the
present invention preferably constitutes from about 0.5 percent to
about 12 percent by weight of the solution that is contained in the
microcapsule, the remainder comprising clomazone and, optionally,
other reagents included for purposes of densitization and
stabilization of the formulation. Preferably, the solution of
clomazone and highly saturated fat includes from about 1 percent to
about 8 percent by weight of the highly saturated fat, and more
preferably about 2 percent to about 6 percent.
[0020] The encapsulating walls of the microcapsules are made of a
porous polymer, such as polyurea, polyamide, polysulfonamide,
polyester, polycarbonate, or polyurethane and comprise from about 5
percent to about 35 percent by weight of each microcapsule.
Preferably, the walls of the microcapsule comprise from about 10
percent to about 25 percent by weight of the microcapsule.
[0021] In a preferred embodiment of the present invention, the
microcapsule preparation comprises an aqueous phase comprised of a
solution containing a suitable emulsifier and an optional
stabilizer, which is preferably an anti-foam agent, and an optional
antimicrobial agent. The emulsifier is preferably selected from the
group of the salts of ligninsulfonic acid, such as, for example,
the sodium, potassium, magnesium, and calcium salts thereof.
Particularly effective is the sodium salt of ligninsulfonic acid,
which is referred to herein as a lignosulfonate emulsifier or
surfactant. An organic phase comprising a solution of clomazone, an
optional organic solvent, a highly saturated fat and a
polyfunctional polyisocyanate, which is added to the composition of
water, lignosulfonate surfactant, and optional antifoam agent.
Preferred organic solvents are selected, without limitation, from
aromatic hydrocarbon solvents with flash points in the range of
about 90 .degree. C. to about 250.degree. C., hydrocarbon
C.sub.15-C.sub.16 mixtures, C.sub.14-C.sub.16 alkyl biphenyl
mixtures, aromatic esters, vegetable oils such as corn oil, soybean
oil, soy salad oil, and hydro-treated oils; refined light
paraffinic distillates, petroleum process oils, and mixtures and
subfractions thereof. Particularly preferred solvents are selected
from aromatic hydrocarbon solvents with flash points in the range
of about 90.degree. C. to about 250.degree. C. A more particularly
preferred solvent is a mixture of C.sub.9-C.sub.15 aromatic
hydrocarbons with a flash point of about 95.degree. C. Preferred,
highly saturated fats are selected from animal fats that include
suet, lard, and tallow. A particularly preferred fat is lard. The
resulting mixture is stirred sufficiently under suitable conditions
well-understood by those skilled in the art to form a homogenous
dispersion of small droplets of the clomazone and fat solution
within the aqueous phase.
[0022] Thereafter, in the preferred protocol, a polyfunctional
amine is added with the stirring being continued until the
polyfunctional amine has essentially fully reacted with the
polyfunctional isocyanate. The polyfunctional isocyanate and the
polyfunctional amine react in the presence of the surfactant under
proper agitation and reaction conditions to form microcapsules
having polyurea walls encapsulating the clomazone, optional
solvent, and fat solution.
[0023] In a another embodiment of the present invention, the
microcapsule preparation comprises an aqueous phase comprised of a
solution containing a suitable emulsifier/cross-linking resin, an
optional stabilizer in the form of an anti-foam agent, and an
optional anti-microbial agent. The emulsifier/cross-linking resin
is preferably derived from the copolymerization product of styrene
and maleic anhydride, or derived from the copolymerization product
of styrene, maleic anhydride and an alcohol. The copolymerization
of styrene and maleic anhydride provides a non-esterified or
anhydride copolymer. When the copolymerization of styrene and
maleic anhydride is conducted with an alcohol, the maleic anhydride
rings open to form a copolymer that is a half-acid and half-ester
of the corresponding alcohol that is in the copolymerization
reaction. Such alcohols include, without limitation, straight or
branched chain lower C.sub.1-C.sub.6 alkyl alcohols. The anhydride
copolymers and the half acid/half ester copolymers are further
reacted with hydroxides such as ammonium hydroxide, sodium
hydroxide, potassium hydroxide, magnesium hydroxide, calcium
hydroxide, and the like, to provide the aforementioned resins in
the form of water-soluble salts. Reaction of the aforementioned
hydroxides with the anhydride copolymer causes the maleic anhydride
rings to open to provide a di-salt, for example, a di-sodium salt
or a di-potassium salt. When the anhydride copolymer is reacted
with, for example, ammonium hydroxide, the maleic anhydride rings
open to provide an amide/ammonium salt. In the context of the
present invention, the emulsifier/cross-linking resin is preferably
selected from the ammonium hydroxide, sodium hydroxide, potassium
hydroxide, magnesium hydroxide, and calcium hydroxide salts of an
anhydrous copolymerization product of styrene and maleic anhydride;
and the ammonium hydroxide, sodium hydroxide, potassium hydroxide,
magnesium hydroxide, and calcium hydroxide salts of a
half-acid/half-ester copolymerization product of styrene and maleic
anhydride. Particularly preferred resins are the ammonium hydroxide
and sodium hydroxide salts of an anhydrous copolymerization product
of styrene and maleic anhydride, most preferred is the ammonium
hydroxide salt.
[0024] An organic phase or solution of clomazone, an organic
solvent, and a polyfunctional polyisocyanate is added to the
composition of water, an emulsifier/cross-linking resin, an
optional anti-foam agent, and an optional anti-microbial agent. The
resulting mixture is stirred sufficiently under suitable conditions
to form a homogenous dispersion of small droplets of the clomazone
and organic solvent within the aqueous phase. Thereafter, a
polyfunctional amine is added with the stirring being continued
until the formation of the microcapsule having polyurea walls
encapsulating the clomazone is complete. During the reaction of the
polyfunctional amine with the polyfunctional isocyanate,
cross-linking of the resin occurs. For example, the amide/ammonium
salt moieties of the ammonium hydroxide salt of the anhydrous
copolymerization product of styrene and maleic anhydride cross-link
with the polyfunctional isocyanate during the microcapsule-forming
reaction and become part of the porous polymer encapsulating wall.
It is believed that the incorporation of the
emulsifier/cross-linking resin into the encapsulating wall in the
manner described, supra, promotes long-term physical stability of
the formulation, inasmuch as the emulsifier has become part of the
microcapsule, and cannot be physically removed by, for example, the
exposure to the elements.
[0025] In a third embodiment of the present invention, the
microcapsule preparation comprises an aqueous phase or solution
containing an emulsifier/cross-linking resin as described, supra,
an optional stabilizer in the form of an anti-foam agent, and an
optional antimicrobial agent. An organic phase or solution of
clomazone, a highly saturated fat, an organic solvent and a
polyfunctional polyisocyanate is added to the composition of water,
emulsifier/cross-linking resin, optional antifoam agent, and
optional antimicrobial agent. The resulting mixture is stirred
sufficiently under suitable conditions to form a homogenous
dispersion of small droplets of the clomazone, fat, and organic
solvent within the aqueous phase. Thereafter, a polyfunctional
amine is added with stirring, during which time crosslinking of the
resin occurs with the polyfunctional polyisocyanate as described
supra.
[0026] The rate of the polymerization will depend on the reaction
conditions employed. The rate of polymerization will generally be
directly related to the temperature at which the reaction takes
place.
[0027] The encapsulation process of the present invention is
capable of satisfactory performance and production of encapsulated
material without adjustment to a specific pH value. However, for
purposes of enhanced stability the pH of the finished
microencapsulated formulations is best maintained in a range of
about 5.0 to about 8.0, preferably about 6.0 to about 7.5, more
preferably about 6.5 to about 7.2. It may be desirable to further
adjust the pH of the finished microcapsule formulation as, for
example, when the aqueous base formulation of the microcapsules is
combined with other herbicides, fertilizers, etc., conventional and
suitable reagents for pH adjustment may be used. Such reagents
include hydrochloric acid, acetic acid, phosphoric acid, sodium
hydroxide, potassium hydroxide, ammonium hydroxide and the
like.
[0028] The agitation employed to establish the dispersion of water
immiscible phase droplets in the aqueous phase during the
production of the formulation of the present invention may be
supplied by any means capable of providing suitable high shear.
That is to say that any variable shear mixing apparatus, e.g., a
Waring Blender, a Brinkman Polytron homogenizer, Ross Model 100L
homogenizer and the like can be usefully employed to provide the
desired shear.
[0029] The particular size of the microcapsules for formulating the
composition of the present invention will generally range from
about one micron up to about one hundred microns in average
diameter. From about one to about twenty microns is a preferred
average range, in which a more preferred average range is about
eight to about fourteen microns
[0030] Salts and other compounds may be employed in the
formulation. Salts and other compounds may: 1) act as antifreezes;
2) increase the ionic strength; and 3) function as densifiers in
the aqueous phase. Examples of such salts include, without
limitation, calcium chloride, sodium nitrate, and combinations
thereof. Other compounds include, for example, urea that functions
as an anti-freeze when incorporated into the formulations of the
present invention.
[0031] The microcapsules of clomazone as set forth herein are
preferably suspended in an aqueous medium that preferably includes
reagents that serve to keep the microcapsules from settling. These
reagents, which form a suspension system composition, preferably
comprise a combination of agents, such as surfactants, dispersants,
emulsifiers, antifreeze agents, clays, water, salts, polymers, and
other suspension stabilizing and density balancing agents,
appropriately selected to keep the microcapsules in stable
homogeneous suspension in the water-based carrier over an extended
period of time, such as, for example, two years or more. The agents
comprising the suspension system will generally comprise 0.01
percent by weight to 15 percent by weight of the formulation,
preferably 1 percent to about 15 percent, more preferably 2 percent
by weight to 10 percent by weight.
[0032] Many such agents can be used, and the optimum combination
for each particular suspension system of active ingredient will
vary. Suitable clays include bentonite clay and attapulgite clay
and mixtures thereof, preferably in the range from about 0.01
percent to about 1.0 percent solid by weight, relative to the total
formulation weight although greater or lesser amounts may be
employed. The presence of at least one clay conventionally used in
suspension systems improves the stability of the suspended
microcapsules and particularly aids in the redistribution of the
microcapsules upon shaking in the event some settling of
microcapsules is experienced and redistribution thereof is
required.
[0033] Another preferred suspension system also includes a small
amount of a polysaccaride thickening agent to aid in stabilizing
the suspension of the microcapsules. Xanthan gum is preferable, and
is preferably present in an amount in the range from about 0.01
percent by weight to about 0. 1 percent by weight although greater
or lesser amounts may be employed.
[0034] The viscosity of the final product comprising the suspension
system of the microcapsules of the present invention is preferably
in the range of about 100 to about 4000 centipoise (cP), more
preferably in the range of about 400 to 3000 cP, and most
preferably, about 600 to about 2000 cP.
[0035] In the preferred final product about 100 to 750 grams of
microcapsules (polymer plus encapsulated material) per liter of the
composition and more preferably about 400 to about 600 grams
microcapsules per liter are present. The encapsulating polymer
component in the final encapsulated product normally will be in the
range of about 0.2 percent by weight to about 12 percent by weight
and preferably in the range of about 2 percent by weight to about 9
percent by weight.
[0036] Within the scope of this invention, polyisocyanates will be
generally understood as meaning those compounds that contain two
and more isocyanate groups in the molecule. Preferred isocyanates
are di- and triisocyanates whose isocyanate groups may be linked to
an aliphatic or aromatic moiety. Examples of suitable aliphatic
diisocyanates and aliphatic triisocyanates are tetramethylene
diisocyanate, pentamethylene diisocyanate, hexamethylene
diisocyanate and 4-(isocyanatomethyl)-1,8-oct- yl diisocyanate.
Suitable aromatic isocyanates are toluene diisocyanate (TDI:
DESMODUR Registered TM VL, Bayer), polymethylene
polyphenylisocyanate (MONDUR Registered TM MR, Miles Chemical
Company); PAPI Registered TM 135 (Upjohn Company), 2,4,4'-diphenyl
ether triisocyanate, 3,3'-dimethyl-4,4'-diphenyl diisocyanate,
3,3'-dimethoxy-4,4'-diphenyl diisocyanate, 1,5-naphthalene
diisocyanate and 4,4',4"-triphenylmethane triisocyanate. A further
suitable diisocyanate is isophorone diisocyanate. Also suitable are
adducts of diisocyanates with polyhydric alcohols, such as ethylene
glycol, glycerol and trimethylolpropane, obtained by addition, per
mole of polyhydric alcohol, of a number of moles of diisocyanate
corresponding to the number of hydroxyl groups of the respective
alcohol. In this way several molecules of diisocyanate are linked
urethane groups to the polyhydric alcohol to form high molecular
polyisocyanates. Another suitable product of this kind (DESMODUR
Registered TM L) can be prepared by reacting three moles of toluene
diisocyanate with one mole of 2-ethylglycerol
(1,1-bismethylolpropane). Further suitable products are obtained by
addition of hexamethylene diisocyanate or isophorone diisocyanate
with ethylene glycol or glycerol. Preferred polyisocyanates are
diphenylmethane-4,4'-diisocyanate and polymethylene
polyphenylisocyanate. The di- and triisocyanates specified above
can be employed individually or as mixtures of two or more such
isocyanates.
[0037] Suitable polyamines within the scope of this invention will
be understood as meaning in general those compounds that contain
two or more primary amino groups in the molecule, which amino
groups may be linked to aliphatic and aromatic moieties. Examples
of suitable aliphatic polyamines are alpha, omega-diamines,
including, without limitation, ethylenediamine,
propylene-1,3-diamine, tetramethylenediamine, pentamethylenediamine
and 1,6-hexamethylenediamine. A preferred diamine is
1,6-hexamethylenediamine.
[0038] Further suitable aliphatic polyamines are
polyethyleneamines, including, without limitation,
diethylenetriamine, triethylenetriamine, tetraethylenepentamine,
pentaethylenehexamine.
[0039] Examples of suitable aromatic polyamines are 1
,3-phenylenediamine, 2,4-toluylenediamine,
4,4'-diaminodiphenylmethane, 1,5-diaminoaphthalene,
1,3,5-triaminobenzene, 2,4,6-triaminotoluene,
1,3,6-triaminonaphthalene, 2,4,4'-triaminodiphenyl ether,
3,4,5-triamino-1,2,4-triazole, bis(hexamethylentriamine) and
1,4,5,8-tetraaminoanthraquinone. Those polyamines which are
insoluble or insufficiently soluble in water may be used as
hydrochloride salts.
[0040] Yet further suitable polyamines are those that contain sulfo
or carboxyl groups in addition to the amino groups. Examples of
such polyamines are 1,4-phenylene diaminesulfonic acid,
4,4'-diaminodiphenyl-2-sulfonic acid, or diaminoammocarboxylic
acids such as ornithene and lysine.
[0041] Suitable liquid fertilizers can be mixed with the
formulations herein without the formation of unacceptable amounts
of agglomerates in the spray tank, thus avoiding poor spraying
performance. The liquid fertilizers used in mixtures of the present
invention can be liquid nitrogen fertilizers, optionally containing
phosphate and/or potash components. Liquid fertilizers are usually
designated by the percentage weight of nitrogen, phosphorous and
potassium (N-P-K) ratios, e.g., 4-10-10, 6-18-18, or 10-30-10.
[0042] The microcapsules of the present invention may be formulated
with at least one other active ingredient. Such other active
ingredient includes other pesticides such as herbicides and
insecticides. Examples of such herbicides include dimethachlor,
ametryn, pendimethalin, and trifluralin. Examples of such
insecticides include bifenthrin, permethrin, cypermethrin, and
organophosphates.
[0043] The present invention is better illustrated and is explained
in more detail in the following examples wherein parts and
percentages are given on a weight basis unless otherwise stated. It
should be understood that the examples are merely illustrative of
the invention and not limitative.
EXAMPLE I
[0044] This example illustrates the preparation of an aqueous
suspension of microencapsulated clomazone in solution with a highly
saturated fat.
[0045] PREPARATION OF A CLOMAZONE 3.0 CS FORMULATION CONTAINING
ANIMAL FAT
[0046] A pre-mixed aqueous phase consisting of 10.00 grams of the
sodium salt of lignosulfonic acid (dispersant-Lignosol SFX65, from
Lignotech; Rothchild, Wis.), and seven drops of a 100% polydimethyl
siloxane (anti-foam agent-Dow Corning 1520US, from Ashland
Chemical; Cleveland, Ohio) in 500.00 grams of water was placed in a
1000 mL beaker. The aqueous phase was homogenized at high speed
(about 6000 rpm) for 60 seconds in a Brinkmann Polytron PT6000
blender, and a pre-mixed organic phase consisting of 20.00 grams of
animal fat (solvent-lard, from Armour; Dallas, Tex.), 70.00 grams
of polymethylenepolyphenyl isocyanate (wall-forming material-PAPI
27, from Dow Chemical; Midland, Mich.), 20.00 grams of a solvent
consisting of a mixture of C.sub.9-C.sub.15 aromatic hydrocarbons
with a flash point of about 95.degree. C. (petroleum based
solvent-Aromatic 200, from Exxon; Houston, Tex.), and 350.00 grams
of clomazone (91% active ingredient) was added. Upon completion of
addition, the high-speed blending was continued for about 120
minutes, then with medium stirring, 50.00 grams of
1,6-hexamethylenediamine (polymerizer-aqueous 70% HMDA from DuPont;
Wilmington, Del.) in 50.00 grams of water was quickly injected into
the aqueous/organic emulsion. With continued stirring, the
temperature of the so-formed microcapsule suspension formulation
was brought to about 60.degree. C. during a 30 minute period, where
it was maintained for about two hours. After this time, the
formulation was cooled to ambient temperature and 50.00 grams of
calcium chloride, 47.50 grams of sodium nitrate (densifiers-from
Aldrich, Milwaukee, Wis.), and 20.00 grams of an aqueous 2% xanthum
gum solution (thickener-Kelzan S from Kelco; Chicago, Ill.) was
added to the formulation to promote the suspension of the
microcapsules in water. Particle size: 10.4 microns (90%),
Viscosity: 320 cP, pH: 7.0.
EXAMPLE II
[0047] This example illustrates the preparation of an aqueous
suspension of microencapsulated clomazone where the microcapsule is
formed in part from the reaction product of the amide/ammonium salt
resin of an anhydrous copolymerization product of styrene and
maleic anhydride and a polyfunctional polyisocyanate.
[0048] PREPARATION OF A CLOMAZONE 3.0 CS FORMULATION CONTAINING A
RESIN COPOLYMER
[0049] A pre-mixed aqueous phase consisting of 5.00 grams of an
aqueous 25% solution of styrene maleic anhydride copolymer
amide/ammonium salt (emulsifier/cross-linking-Scripset 720, from
Solutia, Springfield, Mass.), 1.00 gram of a 100% polydimethyl
siloxane (anti-foam agent-Dow Corning 1520US, from Ashland
Chemical; Cleveland, Ohio), and 0.36 gram of an acidic 1.15%
solution of a mixture of 2-methyl-4-isothiazolin-3-ones (a
microbial growth inhibitor-Legend MK, from Rohm and Haas; Ambler,
Pa.) in about 195.10 grams of water was placed in a 1000ml vessel.
The aqueous phase was homogenized at high speed (about 7000 rpm)
for 10 seconds in a Brinkmann Polytron PT6000 blender, and a
pre-mixed organic phase consisting of 210.00 grams of technical
clomazone (90% active ingredient), 42.00 grams of
polymethylenepolyphenyl isocyanate (wall-forming material-PAPI 27,
from Dow Chemical; Midland, Mich.), and 24.00 grams of a solvent
consisting of a mixture of C.sub.9-C.sub.15 aromatic hydrocarbons
with a flash point of about 95.degree. C. (petroleum based
solvent-Aromatic 200, from Exxon; Houston, Tex.) was added at
ambient temperature. Upon completion of addition, the high-speed
blending was continued for about 10 seconds, then with medium
stirring, 42.00 grams of an aqueous 35% solution of
1,6-hexamethylenediamine (polymerizer-aqueous 70% HMDA from DuPont;
Wilmington, Del.) was quickly injected into the aqueous/organic
emulsion. Upon completion of addition of the amine, the so-formed
microcapsule suspension formulation was warmed to 60.degree. C.
where it stirred for 2 hours, and finally, the formulation was
cooled to ambient temperature where it stirred for about 15
minutes. After this time, 24.00 grams of an aqueous 2% xanthum gum
solution (thickener-Kelzan S from Kelco; Chicago, Ill.) was added
to the formulation during a 15 minute period to promote the
suspension of the microcapsules in water. To this was then added
42.00 grams of urea (widely available) as an antifreeze agent. The
pH of the formulation was then adjusted to about 7.6 by the
addition of about 5.00 grams of acetic acid (Aldrich, Milwaukee,
Wis.). Particle size: 10.0 microns (90%), Viscosity; 900 cP, pH:
7.6.
EXAMPLE III
[0050] This example illustrates the preparation of an aqueous
suspension of microencapsulated clomazone in solution with a highly
saturated fat where the microcapsule is formed in part from the
reaction product of the amide/ammonium salt resin of an anhydrous
copolymerization product of styrene and maleic anhydride and a
polyfunctional polyisocyanate.
[0051] PREPARATION OF A CLOMAZONE 3.0 CS FORMULATION CONTAINING
ANIMAL FAT AND A RESIN COPOLYMER
[0052] A pre-mixed aqueous phase consisting of 12.00 grams of an
aqueous 25% solution of styrene maleic anhydride copolymer
amide/ammonium salt (mulsifier/cross-linking-Scripset 720, from
Solutia, Springfield, Mass.), 2.00 gram of a 100% polydimethyl
siloxane (anti-foam agent-Dow Corning 1520US, from Ashland
Chemical; Cleveland, Ohio), and 0.36 gram an acidic 1.15% solution
of a mixture of 2-methyl-4-isothiazolin-3-ones (a microbial growth
inhibitor-Legend MK, from Rohm and Haas, Ambler, Pa.) in about
204.64 grams of water was placed in a 1000ml vessel. The aqueous
phase was homogenized at high speed (about 7000 rpm) for 10 seconds
in a Brinkmann Polytron PT6000 blender, and a pre-mixed organic
phase consisting of 210.00 grams of technical clomazone (90% active
ingredient), 30.00 grams of polymethylenepolyphenyl isocyanate
(wall-forming material-PAPI 27, from Dow Chemical Company; Midland,
Mich.)), 12.00 grams of animal fat (solvent-lard, from Armour;
Dallas, Tex.) and 12.00 grams of a solvent consisting of a mixture
of C.sub.9-C.sub.15 aromatic hydrocarbons with a flash point of
about 95.degree. C. (petroleum based solvent-Aromatic 200 from
Exxon; Houston, Tex.) was added at 35.degree. C. Upon completion of
addition, the high-speed blending was continued for about 10
seconds, then, with medium stirring, 40.00 grams of an aqueous 35%
solution of 1,6-hexamethylenediamine (polymerizer-aqueous 70% HMDA
from DuPont, Wilmington, Del.) was quickly injected to the
emulsion. Upon completion of addition of the amine, the so-formed
microcapsule suspension formulation was warmed to 60.degree. C.
where it stirred for 2 hours, and finally, the formulation was
cooled to ambient temperature where it stirred for about 15
minutes. After this time, 18.00 grams an aqueous 2% Xanthum gum
solution (thickener-Kelzan S from Kelco; Chicago, Ill.) was added
to the formulation during a 15 minute period to promote the
suspension of the microcapsules in water. To this was then added
60.00 grams of urea (widely available) as an antifreeze agent. The
pH of the formulation was then adjusted to about 7.0 by the
addition of about 3.50 grams of acetic acid (Aldrich, Milwaukee,
Wis.). Particle size: 7.0 microns (90%), viscosity: 800 cP, pH:
7.0.
EXAMPLE IV
[0053] This example illustrates microencapsulated formulations of
clomazone within the scope of the present invention wherein the
components are expressed as ranges in weight/weight percents.
1 CLOMAZONE 3.0 CS FORMULATIONS USING ANIMAL FATS AND/OR COPOLYMER
RESIN Percent weight/weight Formulations Formulations Formulations
of of of Example I Example II Example III Component Aqueous Phase
Na salt of lignosulfonic 1.00-2.00 -- -- acid (Dispersant)
Copolymer resin -- 0.20-1.00 0.20-1.00 (Emulsifier/cross-linking)
Anti-microbial agent -- 0.02-0.10 0.02-0.10 Anti-foam agent
0.10-0.40 0.10-0.40 0.10-0.40 Water (Diluent) 27.82-47.26
29.82-52.12 28.82-48.06 Organic Phase Polymethylene poly- 4.50-8.00
4.50-8.00 4.50-8.00 phenylisocyanate (Wall-forming material) Animal
fat (Solvent) 2.00-3.00 -- 2.00-3.00 Petroleum-based hydro-
0.00-2.50 3.50-4.50 1.50-2.50 carbon (Solvent) Clomazone (90-99%)
34.75-35.50 34.75-35.50 34.75-35.50 Amine Phase 1,6-hexanediamine
1.90-5.00 1.90-5.00 1.90-5.00 (Polymerizer) Water (Diluent)
1.90-5.00 1.90-5.00 1.90-5.00 Post-encapsulation Components Xanthan
gum 0.02-0.08 0.02-0.08 0.02-0.08 (Thickener)
Urea/CaCl.sub.2/NaNO.sub.3 5.00-10.00 5.00-10.00 5.00-10.00
(Antifreeze/densifier) CH.sub.3CO.sub.2H (pH adjust) 0.05-0.60
0.05-0.60 0.05-0.60
EXAMPLE V
[0054] The following example further illustrates the present
invention, but, of course, should not be construed as in any way
limiting its scope. The example sets forth certain biological data
illustrating the efficacy of the microcapsule formulations when
compared to the efficacy of similar formulations known in the
art.
[0055] Seeds of barnyardgrass, giant foxtail, green foxtail,
shattercane, and velvetleaf were planted in a 25 cm.times.15
cm.times.7.5 cm fiber flat containing topsoil. Each species was
planted as a single row in the flat, which contained five rows.
There were four replicate flats of the aforementioned weed species
for each rate of application of clomazone test formulation. Stock
solutions of each of the test formulations were prepared by
dissolving a sufficient amount of formulation to provide 0.0356
grams of active ingredient in 40 mL of water. From the stock
solution 20 mL was removed and serially diluted with 20 mL of water
to provide application rates of 0.25, 0.125. 0.0625, 0.0313,
0.0156, and 0.0078 kg a.i./ha. The solutions of test formulation
for each rate of application were then sprayed onto the surface of
the soil using a track-sprayer in a spray hood. Flats were also
sprayed as above with the same rates of a standard clomazone
formulation sold as Command.RTM. Herbicide 4.0 Emulsifiable
Concentrate (EC). Untreated controls were also included in each
test. Upon completion of the spraying, the flats were placed in a
greenhouse, where they were maintained for fourteen days. After
this time, the test was visually evaluated for percent weed
control. The percent weed control data for each test formulation
and the standard Command Herbicide 4.0 EC formulation was subjected
to regression analysis to determine the rate of application that
would provide 85% weed control (ED85) of each of the weed species.
From these data the relative potency of the test formulation ( the
relative potency of the Command Herbicide 4.0 EC is one) was
determined using the following ratio:
2 1 Formulation Relative Potency = Formulation ED 85 Command
Herbicide ED 85 Formulation Relative Potency Barn- yard- Giant
Green Shetter- Velvet- Formulation grass Foxtail Foxtail cane leaf
Formulation of 1.03* 1.43* 1.09* 1.22* 1.94* Example I Formulation
of 0.75 0.75 0.95 1.04 1.00 Example II Formulation of 0.42* 0.75*
0.59* 0.60* 0.54* U.S. Pat. No. 5,783,520 Command 1.00 1.00 1.00
1.00 1.00 Herbicide 4EC *Average of two tests.
[0056] The formulations of Examples I and II of the present
invention are generally equal in, if not more, herbicidally active
than the standard Command Herbicide 4EC. The formulations of
Example I and II are significantly more herbicidally active than
the formulations of U.S. Pat. No. 5,783,520, ranging from about 1.1
to about 3.6 times more herbicidally active.
[0057] While the invention has been described in detail and with
reference to specific embodiments thereof, it will be apparent to
one skilled in the art that various changes and modifications can
be made herein without departing from the spirit and scope
thereof.
* * * * *