U.S. patent application number 11/599813 was filed with the patent office on 2007-03-15 for agricultural chemical suspensions.
Invention is credited to Robert A. Foster, Ronald E. Highsmith.
Application Number | 20070060479 11/599813 |
Document ID | / |
Family ID | 26926939 |
Filed Date | 2007-03-15 |
United States Patent
Application |
20070060479 |
Kind Code |
A1 |
Highsmith; Ronald E. ; et
al. |
March 15, 2007 |
Agricultural chemical suspensions
Abstract
Stable concentrated suspensions readily dispersible in water
comprising one or more agricultural solids, a single non-ionic
surfactant and a water-soluble glycol liquid. The agricultural
solids include fertilizers, adjuvants, herbicides, pesticides and
combinations thereof approved for use with foods. The non-ionic
surfactant is an alkyl-phenoxy-poly(ethylenoxide)alkanol, an
ethoxylated aliphatic C.sub.11 to C.sub.15 alcohol, an ethylene
oxide-propylene oxide block copolymer or an ethoxylated fatty acid.
Preferably, the surfactant has an average molecular weight from
about 300 to about 1000. The water-soluble glycol liquid is
ethylene glycol, propylene glycol, or mixtures thereof. The
agricultural solid particles are at least about 99 wt. % passable
through a Tyler #48 sieve. The suspensions of the invention exhibit
physical stability during normal storage conditions, good
pourability, and are readily dispersed in water.
Inventors: |
Highsmith; Ronald E.;
(Chesterfield, VA) ; Foster; Robert A.; (Richmond,
VA) |
Correspondence
Address: |
Richard S. Roberts;Roberts & Roberts, LLP
Attoneys at Law
P.O. Box 484
Princeton
NJ
08542-0484
US
|
Family ID: |
26926939 |
Appl. No.: |
11/599813 |
Filed: |
November 15, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09886700 |
Jun 21, 2001 |
|
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11599813 |
Nov 15, 2006 |
|
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60233457 |
Sep 18, 2000 |
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Current U.S.
Class: |
504/206 ;
504/362 |
Current CPC
Class: |
C05G 5/27 20200201; A01N
57/20 20130101; A01N 57/20 20130101; A01N 57/20 20130101; C05G 3/60
20200201; A01N 2300/00 20130101; C05G 3/70 20200201; A01N 25/04
20130101; A01N 25/02 20130101; A01N 25/30 20130101; C05G 3/60
20200201; C05G 3/70 20200201; C05G 3/70 20200201; C05G 5/27
20200201; A01N 25/04 20130101; C05G 5/27 20200201 |
Class at
Publication: |
504/206 ;
504/362 |
International
Class: |
A01N 57/18 20060101
A01N057/18; A01N 25/02 20060101 A01N025/02 |
Claims
1. A stable agricultural solids suspension readily dispersible in
water comprising: a. agricultural solids consisting of at least one
member selected from the group consisting of a fertilizer, an
adjuvant, a herbicide and a pesticide, said agricultural solids
having particles more than about 99 wt. % passable through a Tyler
#48 sieve; b. a single non-ionic surfactant selected from the group
consisting of alkyl-phenoxy-poly(ethylenoxide)alkanols, ethoxylated
aliphatic C.sub.11 to C.sub.15 alcohols, ethylene oxide-propylene
oxide block copolymers and ethoxylated fatty acids; and c. a
water-soluble glycol liquid consisting of at least one member of
the group consisting of ethylene glycol, and propylene glycol.
2-20. (canceled)
21. A water-soluble, stable agricultural solids suspension readily
dispersible in water, the suspension comprising: a. water-soluble
agricultural solids consisting of at least one member selected from
the group consisting of a fertilizer, an adjuvant, a herbicide and
a pesticide, said agricultural solids having particles more than
about 99 wt. % passable through a Tyler #48 sieve; b. a single
non-ionic surfactant selected from the group consisting of
alkyl-phenoxy-poly(ethylenoxide)alkanols, ethoxylated aliphatic
C.sub.11 to C.sub.15 alcohols, ethylene oxide-propylene oxide block
copolymers and ethoxylated fatty acids; c. a water-soluble glycol
liquid consisting of at least one member of the group consisting of
ethylene glycol, and propylene glycol; and d. at least one member
selected from the group consisting of ammonium sulfate
((NH.sub.4).sub.2SO.sub.4), diammonium phosphate
((NH.sub.4).sub.2HPO.sub.4) and the isopropylamine salt of
N-(phosphonomethyl) glycine.
22. The agricultural solids suspension of claim 21, wherein the
concentration of the agricultural solids is between about 20 wt. %
and 80 wt. %; the concentration of the glycol liquid is between
about 20 wt. % and about 80 wt. %; and the concentration of the
non-ionic surfactant is between about 1 wt. % and about 9 wt.
%.
23. The agricultural solids suspension of claim 21, wherein the
concentration of the agricultural solids is between about 50 wt. %
and about 70 wt. %; the concentration of the glycol liquid is
between about 30 wt. % and about 50 wt. %; and the concentration of
the non-ionic surfactant is between about 2.5 wt. % and 6.5 wt.
%.
24. The agricultural solids suspension of claim 21, wherein the
molecular weight of the non-ionic surfactant is between about 300
and 1000.
25. The agricultural solids suspension of claim 21, wherein the
non-ionic surfactant is selected from the group consisting of
dodecylphenoxy poly(ethylene oxide).sub.9.5-11 ethanol,
dodecylphenoxy poly(ethylene oxide).sub.9 ethanol, octylphenoxy
poly(ethylene oxide).sub.7 ethanol, octylphenoxy poly(ethylene
oxide).sub.5 ethanol, and nonylphenoxy poly(ethylene
oxide).sub.4.
26. The agricultural solids suspension of claim 21, wherein the
non-ionic surfactant is selected from the group consisting of a
C.sub.12-C.sub.14 secondary aliphatic alcohol (ethoxylate).sub.9, a
C.sub.12-C.sub.14 secondary alcohol (ethoxylate).sub.12, undecanol
(ethoxylate).sub.9 and oleyl (ethoxylate).sub.10.
27. The agricultural solids suspension of claim 21, wherein the
non-ionic surfactant is dodecylphenoxy poly(ethylene
oxide).sub.9.5-11 ethanol.
28. The agricultural solids suspension of claim 21, wherein the
glycol liquid is propylene glycol.
29. A water-soluble, stable suspension of ammonium sulfate
((NH.sub.4).sub.2SO.sub.4) readily dispersible in water, the
suspension comprising: a. water-soluble ammonium sulfate particles
more than about 99 wt. % passable through a Tyler #48 sieve; b. a
single non-ionic surfactant selected from the group consisting of
alkyl-phenoxy-poly(ethylenoxide)alkanols, ethoxylated aliphatic
C.sub.11 to C.sub.15 alcohols, ethylene oxide-propylene oxide block
copolymers and ethoxylated fatty acids; c. water-soluble glycol
liquid consisting of at least one member of the group consisting of
ethylene glycol, and propylene glycol; and d. at least one member
selected from the group consisting of diammonium phosphate
((NH.sub.4).sub.2HPO.sub.4) and the isopropylamine salt of
N-(phosphonomethyl) glycine.
30. The ammonium sulfate suspension of claim 29, wherein the
concentration of the agricultural solids is between about 30 wt. %
and 70 wt. %; the concentration of the glycol liquid is between
about 30 wt. % and about 70 wt. %; and the concentration of the
non-ionic surfactant is between about 1 wt. % and about 9 wt.
%.
31. The ammonium sulfate suspension of claim 29, wherein the
concentration of the ammonium sulfate is between about 40 wt. % and
70 wt. %; the concentration of the glycol liquid is between about
30 wt. % and about 60 wt. %; and the concentration of the non-ionic
surfactant is between about 1 wt. % and about 9 wt. %.
32. The ammonium sulfate suspension of claim 29, wherein the
concentration of the ammonium sulfate is between about 50 wt. % and
about 70 wt. %; the concentration of the glycol liquid is between
about 30 wt. % and about 50 wt. %; and the concentration of the
non-ionic surfactant is between about 2.5 wt. % and 6.5 wt. %.
33. The ammonium sulfate suspension of claim 29, wherein the
non-ionic surfactant has a molecular weight between about 300 and
about 1000.
34. The ammonium sulfate suspension of claim 29, wherein the
non-ionic surfactant is selected from the group consisting of
dodecylphenoxy poly(ethylene oxide).sub.9.5-11 ethanol,
dodecylphenoxy poly(ethylene oxide).sub.9 ethanol, octylphenoxy
poly(ethylene oxide).sub.7 ethanol, octylphenoxy poly(ethylene
oxide).sub.5 ethanol, and nonylphenoxypoly(ethylene
oxide).sub.4.
35. The agricultural solids suspension of claim 29, wherein the
non-ionic surfactant is selected from the group consisting of a
C.sub.12-C.sub.14 secondary aliphatic alcohol (ethoxylate).sub.9, a
C.sub.12-C.sub.14 secondary alcohol (ethoxylate).sub.12, undecanol
(ethoxylate).sub.9 and oleyl (ethoxylate).sub.10.
36. The ammonium sulfate suspension of claim 29, wherein the
non-ionic surfactant is dodecylphenoxy poly(ethylene
oxide).sub.9.5-11 ethanol.
37. The ammonium sulfate suspension of claim 29, wherein the glycol
liquid is propylene glycol.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of provisional
application Ser. No. 60/233,457 filed Sep. 18, 2000 and is related
to co-pending application Ser. No. 09/855,481 filed May 15, 2001,
2001 entitled "Ammonium Sulfate Suspensions in Oils".
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to concentrated glycol
suspensions of water-soluble agricultural materials having superior
stability and pour properties, and that upon dilution in a suitable
volume of water, are suitable for application to plants as
herbicidal compositions, adjuvants in herbicidal compositions, or
fertilizers, or that may be used for other purposes.
[0004] 2. Description of the Related Art
[0005] When growing crops in a field, it is important to kill or
control the growth of undesirable plants (weeds) in the field. If
not controlled, the weeds compete with crop plants for essential
resources such as soil nutrients, water and sunlight. By removing a
fraction of the resources or otherwise reducing the availability of
these resources to crop plants, the weeds restrict crop growth,
resulting in loss of crop yield.
[0006] Timely and judicious use of herbicides can provide weed
control to minimize crop losses and production costs. Herbicides
such as glyphosate (N-phosphonomethyl glycine) and many others are
useful for control of a large variety of weeds. When used in an
herbicidal composition, glyphosate is generally in the form of one
of its various salts in solution, preferably an aqueous
solution.
[0007] Adjuvants are materials that enhance the action of
herbicides by promoting adsorption and translocation and by
complexing antagonistic metal ions in the water used to make the
herbicide solution. Ammonium sulfate has been known as an adjuvant
for several decades. It is perhaps the most important commercial
adjuvant and is also widely used as a fertilizer.
[0008] Herbicides are typically applied to field crops by spraying
an aqueous mixture of several components. Polymers that inhibit
spray drift, defoamers, and other chemicals that enhance the
performance of an herbicide are sometimes mixed with the ammonium
sulfate. All components of a mixture are typically ground to a
small particle size in order to reduce the time required to
dissolve. Growers and contract applicators use a "mix" tank to
prepare the herbicide mixture. A typical mix consists of about 800
pounds of water, 8 to 17 pounds of herbicide, and 8 to 17 pounds of
dry adjuvant. The result is a 1% or 2% solution of herbicide and 1%
or 2% of adjuvant. The typical tank has relatively poor mixing and
the applicator, whether using a truck or airplane, usually has
little time to wait for dissolution. Even small particles tend to
fall to the bottom of the mix tank in clumps and are sometimes slow
to dissolve. In addition, dry materials may generate undesirable
dusty conditions, absorb moisture, tend to cake, and are difficult
to meter.
[0009] Liquid preparations facilitate use. However, liquids may
suffer disadvantages because of low product concentration.
Agricultural materials of interest have limited water solubility.
Freight, handling, and packaging costs can become a substantial
part of the total product cost. As an example, the highest
practical concentration of ammonium sulfate in aqueous solution is
about 38%. This concentration drops to about 34% if drift retardant
polymer is included. Water is the only practical solvent because
ammonium sulfate is practically insoluble in all other common
solvents. Thus, while aqueous solutions are not satisfactory, there
remains a need for liquid agricultural products.
[0010] An alternative approach to a liquid product is to create a
suspension. Many examples of aqueous suspensions of agricultural
materials are known in the art. Japanese patents JP 05105606, JP
02104502, EP 253682, and U.S. Pat. No. 4,526,606 are exemplars.
However, in aqueous suspensions of water-soluble materials, crystal
dissolution and recrystallization occurs continually. This results
in a progressive increase of the size of the particles and eventual
settling. Therefore, it is desirable and convenient to be able to
prepare high concentration suspensions of agricultural solids in
liquids in which they are not appreciably soluble.
[0011] In order for solid materials, which are generally denser
than liquids to remain suspended, they must be broken up into small
particles. Generally, the smaller the particle the more stable the
suspension. Colloidal particles of 0.001 mm (1 micron) or less in
diameter form stable suspensions because of Brownian motion.
However, the energy required to break down ammonium sulfate and
most other materials to colloidal dimensions is extremely high and
impractically costly.
[0012] The liquid in a suspension intended for agricultural
purposes must comply with government regulations, and should be
qualified for use with pesticides under the Code of Federal
Regulations (C.F.R.). The liquid may be soluble or insoluble in
water. Mineral oils and a few other oils such as soybean oil are
approved for agricultural use under 40 C.F.R.180.1001, paragraph c
and have been used as adjuvants themselves. Petroleum distillates
are also approved under this section of the C.F.R. provided they
conform to the conditions of 21 C.F.R.172.882 or 21 C.F.R. 172.884.
Co-pending application Ser. No. 09/855,481 describes useful
suspensions of agricultural materials in water-insoluble oils.
[0013] However, suspending liquids that are water-soluble may be
advantageous in that they have the potential to facilitate
dispersion and dissolution of suspended solids in the applicator's
"mix" tank. Of importance to this invention, propylene glycol and
dipropylene glycol are approved for agricultural use under
paragraph c of 40 C.F.R. 180.1001, and ethylene glycol and
diethylene glycol are approved under paragraph d of the same
part.
[0014] It is not yet possible to predict what combination of liquid
and solid will yield a stable suspension. There is little
understanding of the fundamentals of suspensions. For instance, Yan
et. al. state that, "the effect of particle size on the rheology of
suspensions is a controversial subject" (Y. Yan, et.al., Chem, Eng.
Sci., 46(4), 985-994, (1991)). Other authors have claimed that the
shape and ionic character of the particles can be important
factors. For instance, R. M. Turian, et. al. in a paper published
in Powder Technology, 93, 219-223 (1997) suggests that the
"interparticle interaction effects were quite strong" for the
suspensions he investigated. It is to be expected that different
particles may present uniquely different properties.
[0015] Problems with use of agricultural suspensions may include
syneresis, inability to pour, and difficulty dissolving. To begin
with, suspensions must be stable. Syneresis is a phenomenon of
phase separation marked by free clear liquid separating from a
suspension. It is undesirable because it results in an
inhomogeneous mixture. The most convenient method of measuring
syneresis is to measure the depth of the free liquid in a container
after sitting for some period of time compared to the total depth
of the suspension and expressing the result in terms of percentage
or fraction.
[0016] The first step in using an agricultural suspension is
pouring it from its shipping container into a mix tank to be
diluted for application. It is necessary that the suspension have
the ability to be conveniently and quantitatively transferred from
one container to another under the influence of gravity, i.e. to
have good pourability. Pourability and suspension stability may be
competitive properties. As previously noted, suspension stability
generally increases as particle size decreases. However, suspension
viscosity tends to increase as particle size becomes smaller.
Suspension stability also generally increases with a higher
viscosity suspending liquid. With some choices of particle size and
suspending liquid the viscosity can become so high that the
suspension will no longer pour. A balance between stability and
pourability must be achieved.
[0017] The solids in a suspension must be readily dispersed and/or
dissolved in a mix tank. If a suspension is too viscous or
otherwise antagonistic toward water, the suspension will remain as
large globules in the water and the suspended solids will be slow
to dissolve. Dispersion means that the globules of the suspension
break up into small liquid droplets to form a milky volume in the
water. This is sometimes referred to as "bloom". The resulting high
surface area allows the solid particles rapid access to water where
they can dissolve quickly. Vigorous agitation can also result in
good dispersion, but in mix tanks where agitation is frequently
marginal, the ability of a suspension to quickly and spontaneously
"bloom" can significantly reduce dissolving times.
[0018] Suspensions are well known in the art although few have been
reported that employ non-aqueous liquids. For instance, U.S. Pat.
No. 3,793,015 and British Patent GB 1,151,141 reported stable
suspensions of particles such as carbon black in aliphatic
hydrocarbons using metal salts of pyrophosphates and similar agents
as dispersing agents. The suspensions were described as useful in
imaging such as xerography. U.S. Pat. No. 3,317,635 reported
dispersions of polymer particles in organic liquids. These are
different than conventional suspensions of solid materials since
they are prepared by in situ polymerization of aqueous liquid
droplets in a hydrocarbon fluid. U.S. Pat. No. 4,393,151 described
suspensions of water-soluble polymers in a liquid hydrocarbon
medium including a thickening agent. German Patent 2312372
described suspensions of polishing agents such as alumina, zirconia
and silicon carbide in ethylene glycol thickened with a neutralized
carboxymethylene resin. These suspension were not designed to be
dispersible in water.
[0019] Surfactants and soluble polymers are often used to stabilize
suspensions of particles. These may function by adsorption on the
particle surface and may provide steric interference that inhibits
settling. However, the interaction between a particular liquid,
particle, and surfactant is impossible to predict.
[0020] Suspensions of water-soluble solids in non-aqueous water
miscible fluids such as glycols, ketones, and alcohols are
described in U.S. Pat. Nos. 5,707,551 and 5,906,962. Specific
examples are suspensions of potassium nitrate and of ammonium
dihydrogen phosphate in propylene glycol and diethylene glycol.
Stability of the suspensions is obtained through use of a
surfactant system having three necessary components and the
possible inclusion of water. U.S. Pat. No. 5,906,962 describes a
similar surfactant system additionally containing a water
hydratable polysaccharide.
[0021] The first necessary component of U.S. Pat. No. 5,707,551 is
a nonionic polymeric "viscosity improver", preferably a polymeric
material with a volume mass of less than 15,000. The patent states
that the "viscosity improver" increases viscosity. Most preferably,
the "viscosity improvers" are ethylene-oxide-propylene oxide block
copolymers having molecular weights between 1,122 and 15,000.
Specific examples are the high molecular weight
ethoxylated-propoxylated block copolymers ANTAROX.RTM. F-88 of
8,082 molecular weight, and ANTAROX.RTM. F-108 of 10,812 molecular
weight. Among the possible "viscosity improvers" suggested by U.S.
Pat. No. 5,707,551 are included the genera of ethoxylated alkyl
phenols and ethoxylated aliphatic alcohols. No specific species of
these genera are identified.
[0022] The second necessary component in U.S. Pat. No. 5,707,551 is
an anionic surfactant whose functions are to control the viscosity
increase caused by the first component and to adhere to the surface
of the suspended solids.
[0023] The third necessary component is a bulky nonionic surfactant
having a large hydrophobic substituent group. Such materials are
known to provide steric interference that inhibits settling.
[0024] A fourth optional component in U.S. Pat. No. 5,707,551 is
water. The water may be added to adjust the temperature coefficient
of solubility of the suspended solids.
[0025] As noted above, U.S. Pat. No. 5,906,962 describes a similar
surfactant system that includes yet an additional component
consisting of a hydratable polysaccharide.
[0026] It is evident that the suspension systems described by U.S.
Pat. Nos. 5,707,551 and 5,906,962 are complex, require much time
and effort to adjust for each suspended solid, and are costly to
manufacture and control. A need exists for a non-aqueous,
water-soluble suspension system for agricultural solids that is
simple, economic and easy to adjust for different suspended solids.
In particular, a need exists for simple, low cost, stable,
concentrated suspensions of ammonium sulfate that are readily
dispersible in water and for other purposes.
SUMMARY OF THE INVENTION
[0027] The invention provides stable concentrated suspensions
comprising agricultural solids, a single surfactant, and a
water-soluble glycol liquid approved for agricultural application.
An agricultural solid is a fertilizer, an adjuvant, a herbicide or
a pesticide registered, or exempt from registration under 40 C.F.R.
180, "Tolerances and Exemptions From Tolerances For Pesticides in
Food", Jul. 1, 2000.
[0028] In one embodiment, the invention provides stable
concentrated suspensions comprising ammonium sulfate, a single
surfactant and a water-soluble glycol liquid approved for
agricultural application
[0029] The surfactant is a non-ionic
alkyl-phenoxy-poly(ethylenoxide)alkanol, an ethoxylated aliphatic
C.sub.11 to C.sub.15 alcohol, an ethylene oxide-propylene oxide
block copolymer or an ethoxylated fatty acid. Preferably, the
surfactant has an average molecular weight from about 300 to about
1000. The water-soluble glycol liquid is ethylene glycol, propylene
glycol, or mixtures thereof. The agricultural solid particles are
at least about 99 wt. % passable through a Tyler #48 sieve. The
suspensions of the invention exhibit physical stability during
normal storage conditions, good pourability, and are readily
dispersed in water.
[0030] In another embodiment, the ammonium sulfate suspensions of
the invention additionally contain methylthio-.alpha.-hyroxybutyric
acid. It is surprisingly found that
methylthio-.alpha.-hyroxybutyric acid enhances the stability and
reduces the viscosity of the ammonium sulfate suspensions of the
invention.
[0031] Suspensions of the invention containing ammonium sulfate,
propylene glycol, and dodecylphenoxy poly(ethylene oxide) ethanol
surfactant, diluted in water, and in combination with a herbicide,
exhibit synergistic effects in killing difficult weeds. Herbicide
manufacturers usually recommend applying double the dose of
herbicide when difficult weeds are present. However, from an
environmental point of view it is more desirable to use less
herbicide and an adjuvant to obtain the same effect. The
suspensions of the invention meet that need.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawing figures:
[0032] FIG. 1 shows plots of fractional discharge vs time for two
suspensions of the invention
DETAILED DESCRIPTION OF THE INVENTION
[0033] The products of the invention are stable concentrated
suspensions of agricultural solids readily dispersible in water.
Preferably, the suspensions, upon dilution in a suitable volume of
water, are suitable for application to plants as herbicidal
compositions, adjuvants in herbicidal compositions, or fertilizers,
or may be used for other purposes. For the purposes of this
invention, an agricultural solid is a fertilizer, an adjuvant, a
herbicide or a pesticide registered, or exempt from registration
under 40 C.F.R. 180, "Tolerances and Exemptions From Tolerances For
Pesticides in Food", Jul. 1, 2000.
[0034] The invention provides stable concentrated suspensions
comprising agricultural solids, a single surfactant, and a
water-soluble glycol liquid approved for agricultural application.
More particularly, the invention provides stable concentrated
suspensions comprising ammonium sulfate, a surfactant and a
water-soluble glycol liquid approved for agricultural
application
[0035] An agricultural suspension of the invention is comprised of:
agricultural solids consisting of at least one member selected from
the group consisting of a fertilizer, an adjuvant, a herbicide and
a pesticide, said agricultural solids having particles more than
about 99 wt. % passable through a Tyler #48 sieve; a single
non-ionic surfactant selected from the group consisting of
alkyl-phenoxy-poly(ethylenoxide)alkanols, ethoxylated aliphatic
C.sub.11 to C.sub.15 alcohols, ethylene oxide-propylene oxide block
copolymers and ethoxylated fatty acids; and a water-soluble glycol
liquid consisting of at least one member of the group consisting of
ethylene glycol, and propylene glycol.
[0036] More particularly, the invention provides stable
concentrated suspensions comprising ammonium sulfate particles more
than about 99 wt. % passable through a Tyler #48 sieve; a single
non-ionic surfactant selected from the group consisting of
alkyl-phenoxy-poly(ethylenoxide)alkanol, ethoxylated aliphatic
C.sub.11 to C.sub.15 alcohols, ethyleneoxide-propylene oxide block
copolymers, and ethoxylated fatty acid; and a water-soluble glycol
liquid consisting of at least one member of the group consisting of
ethylene glycol, and propylene glycol.
[0037] In another embodiment, the ammonium sulfate suspensions of
the invention additionally contain methylthio-.alpha.-hyroxybutyric
acid.
[0038] The invention is based on the discovery that agricultural
solids, having particles within a certain size range, and in a
concentration range, in combination with a single surfactant can
form stable suspensions in glycol liquids having both good
stability and good pourability. This is a surprising result as the
closest prior art system for suspending water-soluble solids in
glycol liquids has no fewer than three required surfactants of
different genera. The suspensions of the present invention are
therefore much simpler to formulate and to produce, and are more
economic than the suspensions of the prior art.
[0039] Generally any agricultural solid fertilizer, adjuvant,
herbicide or pesticide or combination thereof having particles more
than about 99 wt. % passable through a Tyler #48 sieve may be
incorporated in a suspension of the invention. The concentration of
the solid materials in the suspension should be between 20 wt. %
and about 80%, and preferably between 50 and about 70%.
[0040] Preferred agricultural solids are ammonium sulfate
((NH.sub.4).sub.2SO.sub.4), diammonium phosphate
((NH.sub.4).sub.2HPO.sub.4) the isopropylamine salt of
N-(phosphonomethyl) glycine and combinations thereof. The last
named material is manufactured by Monsanto Co. and is sold under
the name of RoundUp.RTM. DryPak. Ammonium sulfate is most
preferred.
[0041] Generally, any ordinary ammonium sulfate that is
commercially available and suitable for use as fertilizer may be
used in the suspensions of this invention. One example of useful
ammonium sulfate is commercially available from Honeywell
International Inc. Preferably, the ammonium sulfate to be used in
this invention is of at least about 95 wt % purity and contains
less than about 0.2 wt % of water insoluble (filterable) organic or
carbonaceous impurities. The filterable impurities are determined
by dissolving 10 wt % of the ammonium sulfate in water at
23.degree. C., then passing at least 50 g of the solution through a
membrane filter of 0.45 micrometer opening size (e.g. Gelman
Supor.RTM. brand filter). The organic and carbonaceous content as
determined by combustion analysis of the dried filter cake should
be less than about 0.2 wt % of the ammonium sulfate.
[0042] The particle size and particle size distribution of the
ammonium sulfate are important to achieving the objectives of the
invention. Generally, the smaller the particle the higher the
viscosity and the better the stability of the suspensions. It is
too costly to separate specific sizes of particles. It is desirable
to be able to utilize the size distribution resulting from common
grinding processes The suspensions of the invention have this
advantage.
[0043] The ammonium sulfate particles used in the invention are
substantially passable through a Tyler #48 sieve. It is preferred
that at least 8 wt. % of the ammonium sulfate particles pass a
Tyler #230 sieve. A most preferred particle size range for ammonium
sulfate is as follows: TABLE-US-00001 Weight % Retained on Tyler
Sieve No. Opening Size, mm Sieve 48 0.30 Less than 1 60 0.25 0-10
80 0.18 0-20 100 0.15 0-35 200 0.075 10-30 230 0.060 30-50 400 0.03
10-40 pan 0 10-20
[0044] This is representative of the size range produced by
commercial ball milling of ammonium sulfate and requires no
separation except substantial removal of particles retained by the
Tyler #48 sieve.
[0045] The concentration of ammonium sulfate in a suspension of the
invention should be between about 30 wt. % and 70 wt. %. It is
preferred that the ammonium sulfate concentration be between about
40 wt. %. and 70 wt. % More preferably, the ammonium sulfate
concentration should be between about 50 wt. %. and 70 wt. %.
[0046] It is desirable to prepare a single product with a
combination of a herbicide, ammonium sulfate adjuvant and a
fertilizer. The additional particles can be ground with the
ammonium sulfate or the suspension can be made and then the
additional particles added to the suspension.
[0047] The single non-ionic surfactant in a suspension of the
invention is from the group consisting of
alkyl-phenoxy-poly(ethylenoxide)alkanols, ethoxylated aliphatic
C.sub.11 to C.sub.15 alcohols, ethylene oxide-propylene oxide block
coplymers and ethoxylated fatty acids. For the purposes of this
patent, a "single surfactant" is a surfactant that falls within a
single chemical genus but may include a mixture of species having
molecular weights differing by up to 150 g/mol. Thus, the "single
surfactant" specifically includes ethoxylated derivatives having a
limited range of carbon atoms and/or ethoxy units. More
specifically, the "single surfactant" includes ethoxylated
derivatives of partially purified aliphatic alcohols or fatty acids
having a limited range of molecular weights.
[0048] Preferably, the non-ionic surfactant possesses an average
molecular weight from about 300 to about 1000. Surprisingly, and
contrary to theory, non-ionic surfactants within this molecular
weight range yield more stable suspensions than higher molecular
weight surfactants. Preferred
alkyl-phenoxy-poly(ethylenoxide)alkanols, include dodecylphenoxy
poly(ethylene oxide).sub.9.5-11 ethanol.sup.1 of about 713 average
molecular weight (MW) available under the tradename Igepal.RTM.
RC-630, dodecylphenoxy poly(ethylene oxide).sub.9 ethanol of about
643 MW (Igepal.RTM. RC-520), octylphenoxy poly(ethylene
oxide).sub.7 ethanol of about 514 MW (Igepal.RTM. CA-630),
octylphenoxy poly(ethylene oxide).sub.5 ethanol of about 426 MW
(Igepal.RTM. CA-520) and nonylphenoxy poly(ethylene oxide).sub.4
ethanol of about 396 MW (Witconol.RTM. NP40). The Igepal.RTM.
surfactants are products of Rhodia Inc. The Witconol.RTM. is a
product of Witco Corporation. .sup.1The subscript indicates the
number of ethylene oxide units in the compound.
[0049] Preferred ethoxylated alcohols include a C.sub.12-C.sub.14
secondary aliphatic alcohol (ethoxylate).sub.9 of about 596 average
MW (Tergitole.RTM. 15-S-9), a C.sub.12-C.sub.14 secondary alcohol
(ethoxylate).sub.12 of about 728 average MW (Tergitol.RTM.
15-S-12), and undecanol (ethoxylate).sub.9 of about 568 MW
(Neodol.RTM. 1-9). The Tergitol.RTM. surfactants are products of
the Union Carbide Division of Dow Chemical. The Neodol.RTM. is a
product of Shell Chemical. A preferred ethoxylated acid is oleyl
(ethoxylate).sub.10 of about 708 MW (Brij.RTM. 97), a product of
Uniqima Corporation.
[0050] The most preferred surfactant is dodecylphenoxy
poly(ethylene oxide).sub.9.5-11 ethanol of about 713 average
molecular weight (MW) available under the tradename Igepal.RTM.
RC-630.
[0051] The concentration of the surfactant is between about 1 wt. %
and about 9 wt. % in a suspension of the invention. Preferably the
surfactant concentration is about 2.5 wt. % to about 6.5 wt. %.
[0052] The water-soluble glycol liquids approved for agricultural
application are ethylene glycol, diethylene glycol, triethylene
glycol, propylene glycol and dipropylene glycol. Preferred in this
invention are ethylene glycol and propylene glycol. Most preferred
is propylene glycol.
[0053] The concentration of the glycol liquid is between about 20
wt. % to about 80 wt. % of the suspension of the invention,
preferably, between about 30 wt. % to about 70 wt. %, more
preferably between about 30 wt. % to about 60 wt. %, and most
preferably, between about 30 wt. % to about 50 wt. %.
[0054] Surprisingly, It has been found that incorporation of about
0.03 to 2 wt. % of methylthio-.alpha.-hydroxybutyric acid (chemical
formula: CH.sub.3SCH.sub.2CH.sub.2CH(OH)COOH) further enhances the
stability and further reduces the viscosity of the suspensions of
the invention. Over one hundred other compounds had been screened
for this purpose without success and there appears to be no prior
art reference suggesting this functionality for
methylthio-.alpha.-hydroxybutyric acid. The synthesis of
methylthio-.alpha.-hydroxybutyric acid has been described in U.S.
Pat. No. 2,745,745 hereby incorporated by reference to the extent
not incompatible herewith. Methylthio-.alpha.-hydroxybutyric acid
is an article of commerce sold as an animal feed supplement by
Aventis Animal Nutrition, Alpharetta, Ga. in the form of an 88%
aqueous solution under the tradename Rhodimet.RTM. AT-88.
[0055] The suspensions of the invention can be prepared by simple
mixing of the ingredients provided that the solid particles have
been previously ground to the proper size. The mixing can be done
by any of the well known methods for combining solids and liquids
such as described in Perry's Chemical Engineers Handbook, Sixth
Edition, P. 19.5-19.24, McGraw Hill, New York, 1983. In some cases
it may be desirable to grind or mill the solids in the glycol
liquid but this choice is well known in the art of grinding. Any
conventional means of providing uniform mixing is suitable such as
pug mills, blenders, agitated tanks, and helical mixers. The order
of introduction of the materials appears to not be critical, but
usually the surfactant is added last to provide a more uniform
distribution of the surfactant.
[0056] The suspensions of the invention are characterized by
stability and pourability. Experience has shown that suspensions
that are stable for several days are stable for periods exceeding
six months. Suspension stability was determined by leaving a sample
sit undisturbed at room temperature (20-23.degree. C.) for one or
more days and measuring the volume of the free liquid that
separated by syneresis relative to the volume of the suspension.
The suspensions of the invention exhibit a syneresis percentage
less than 10 vol. % after 2 days preferably less than 5 vol. % and
most preferably less than 1 vol %.
[0057] It should be noted that this method of determining syneresis
percentage is much more demanding than the method described in U.S.
Pat. No. 5,707,551 where the suspension container is tumbled
through thirty inversions before measuring any free liquid.
[0058] Several days after preparation, suspension samples were also
examined for ability to pour. Pourability ratings were determined
by the speed and the completeness of flow of a suspension from a
tilted beaker. A value of 5 was assigned if the sample had a flow
about that of water, a value of 0 if there was no immediate flow
indicating a possible Bingham plastic state, and intermediate
values between these two extremes. Suspensions of the invention
have pourability ratings of 2 or better, preferably 3 or better and
most preferably 4 or better.
[0059] A quantitative measure of pourability was obtained as
follows: The suspension to be characterized was prepared in a total
quantity of 15.65 g. After thorough mixing in a beaker, this
suspension was transferred quickly (less than 10 seconds) into a
glass funnel of 60.degree. cone angle, and having a stem of 4 mm
inside diameter and of 60 mm length. The rate at which a suspension
was discharged from the funnel stem was measured by means of a
scale and recorded vs. time. The approximate relationship between
the relative pourability rating and the time required for 90% of
the suspension (14.1 g) to discharge through the funnel was as
follows: TABLE-US-00002 90% Discharge Time, minutes Pourability
Rating <5 5 10-15 4 25-30 3 40-50 2 >60 1
[0060] Intermediate discharge times were taken to correspond
approximately to intermediate pourability ratings. As an example, a
discharge time of 20 minutes corresponded approximately to a 3.5
pourability rating.
[0061] The following examples are presented to provide a more
complete understanding of the invention. The specific techniques,
conditions, materials, proportions and reported data set forth to
illustrate the principles of the invention are exemplary and should
not be construed as limiting the scope of the invention.
EXAMPLE 1
[0062] Ammonium sulfate granules of approximately 1 mm average size
were obtained from Rhone-Poulenc. The granules were 98 wt. %
ammonium sulfate containing less than 0.1 wt. % of water insoluble
carbonaceous impurities. Forty pounds of this material were ball
milled at the Union Process Company, Akron, Ohio. The ammonium
sulfate was charged to a size 1S ball mill together with 1/4 inch
(6.35 mm) stainless steel balls and batch dry ground at 350 RPM for
55 minutes. Cooling water on the ball mill jacket maintained the
batch temperature at about 23.degree. C. At the completion of the
ball milling, the ammonium sulfate was screened to remove
substantially all particles not passable through a Tyler #48
screen. The particle size distribution of the screened material was
as follows in Table I. TABLE-US-00003 TABLE I Tyler Sieve No.
Opening size, mm Wt. % Retained 48 0.30 Less than 0.1 60 0.25 0.3
80 0.18 0.4 100 0.15 0.3 200 0.075 18 230 0.060 49 400 0.030 19 pan
0 13
COMPARATIVE EXAMPLE 2
[0063] To determine if satisfactory suspensions of ammonium sulfate
can be prepared in a glycol without the presence of a surfactant,
the following experiment was performed. Three mixtures of the
milled and sieved ammonium sulfate described in Example 1 were
prepared with propylene glycol, ethylene glycol and diethylene
glycol respectively, each in weight ratios of 61.7/38.3 (w/w) %
ammonium sulfate/glycol. No surfactant was added to the mixtures.
The glycols had been obtained from Fisher Scientific. The ethylene
glycol had a boiling range of 196-199.degree. C. The propylene
glycol and diethylene glycol were of 99.5% purity.
[0064] After only 24 hours it was obvious that the mixtures were
not satisfactory suspensions. The mixture prepared with propylene
glycol exhibited some pourability for its top half, however the
bottom half of the sample was a thick crumbly-type of solid. The
mixture prepared using ethylene glycol had less pourability in its
top portion and the residue at the bottom was a little less stiff
than the propylene glycol mixture. The mixture prepared with
diethylene glycol was very similar to the propylene glycol sample
having a thick residue at the bottom of the container.
EXAMPLES 3-5 AND COMPARATIVE EXAMPLES 6-13
[0065] The following examples show the effect of single surfactants
of different types, non-ionic, anionic and cationic, and of
differing molecular weights, on the pourability of ammonium sulfate
suspensions. Several portions of the milled and sieved ammonium
sulfate described in Example 1 were each thoroughly mixed in a
beaker with propylene glycol (Fisher Scientific, 99.5% assay) in
proportions of 61.7/38.3 (w/w) % respectively. This was followed by
admixing in each portion a single one of the surfactants indicated
in Table II below. Ammonium sulfate concentration in the suspension
varied slightly from 57.0 to 59.2 wt. % depending on how much
surfactant was added to the mixture.
[0066] The suspensions were left to stand undisturbed at room
temperature after preparation until examination for pourability
after 2, 5, and 8 days. The compositions of the suspensions and the
pourability ratings are shown in Table II below. The pourability
ratings obtained on day 2 were consistent with the pourabilities
observed on day 5 and day 8 except for the Adogen.RTM. 464S sample.
This suspension exhibited some thickening at the bottom of the
beaker and its pourability declined with time.
[0067] The best pourability was obtained with nonionic surfactants,
particularly with the two surfactants having molecular weights
around 700 g/mol. TABLE-US-00004 TABLE II Example Approx. or Avg.
Comp. Ex. Name of Molecular Wt. % Pourability No. Surfactant
Description of Surfactant Weight Surfactant Rating* NON-IONICS 3
Igepal RC-630 Dodecylphenoxy poly(ethylene oxide).sub.9.5-11 713
5.7 4 ethanol 4 Tergitol .RTM. 15-S-12 C.sub.12-C.sub.14 secondary
alcohol (ethoxylate).sub.12 728 7.5 4 5 Synperonic .RTM. Ethylene
oxide/propylene oxide block 2100 4.1 3 PE/L61 copolymer 6 Tween
.RTM. 85 Poly(ethylene oxide).sub.20 sorbitan trioleate 1838 4.5 1
(Comp.) 7 Atlox .RTM. 4912 12-hydrostearic acid (propoxylate) 4900
4.3 1 (Comp.) 8 Pergosperse .RTM. Polyethylene glycol(400)dioleate
932 5.3 1 (Comp.) 400DO 9 Zephrym .RTM. Polymeric ester 5000 5.0 1
(Comp.) PD2206 ANIONICS 10 Rhodameen .RTM. Poly(oxyethylated).sub.5
tallow amine 477 4.5 1 (Comp.) PN-430 11 Mazeen .RTM.
2-(dibutylamino)amine 161 4.8 1 (Comp.) DBA1Amine 12 Foamphos .RTM.
NP-3 Nonoxynol-3 phosphate 696 4.1 1 (Comp.) CATIONIC 13 Adogen
.RTM. 464S Methyl Itri C.sub.8-C.sub.10 quaternary ammonium 445 4.1
3 (Comp.) chloride *5 = water-like 0 = did not flow immediately
(possible Bingham plastic state)
EXAMPLES 14-24
[0068] The following examples show the effects on the stability and
pourability of ammonium sulfate suspensions of several non-ionic
surfactants having molecular weights in the range of about 396 to
about 2400.
[0069] Several portions of the milled and sieved ammonium sulfate
described in Example 1 were each thoroughly mixed with propylene
glycol (Fisher Scientific, 99.5% assay) and surfactant in a beaker.
Ammonium sulfate, propylene glycol and surfactant concentrations
were 58.9 wt. %, 36.6 wt. % and 4.5 wt. % respectively with one
exception. The exception was the suspension containing Tegitol.RTM.
15-S-12 which had ammonium sulfate, propylene glycol and surfactant
concentrations of 59.3 wt. %, 36.9 wt. % and 3.8 wt. %
respectively.
[0070] The suspensions were left undisturbed for two days at room
temperature after preparation. The compositions of the suspensions,
the syneresis, and pourability observations after two days are
shown in Table IIII.
[0071] The best combination of stability (zero syneresis) and very
good pourability was obtained with dodecylphenoxy
poly(ethyleneoxide).sub.9.5-11 ethanol (about 713 MW) obtained
commercially as Igepal.RTM. RC-630, with dodecylphenoxy
poly(ethylene oxide).sub.9 ethanol (about 653 MW) obtained
commercially as Igepal.RTM. RC-520, with tridecyl alcohol
(ethoxylate).sub.6 (about 464 MW) obtained commercially as
Witconol.RTM. TD-60, and with nonylphenol (ethoxylate).sub.4
obtained commercially as Witconol.RTM. NP-40. TABLE-US-00005 TABLE
III Ex. or Approx. Avg. Comp. Ex. Name of Molecular Vol. %
Pourability No. Surfactant Description of Surfactant Weight
Syneresis Rating* 14 Igepal .RTM. RC-630 Dodecylphenoxy 713 0 4
poly(ethyleneoxide).sub.9.5-11 ethanol 15 Igepal .RTM. RC-520
Dodecylphenoxy poly(ethylene oxide).sub.9 653 0 4 ethanol 16 Igepal
.RTM. CA-630 Dodecylphenoxy poly(ethylene oxide).sub.7 514 5.2 4
ethanol 17 Igepal .RTM. CA-520 Dodecylphenoxy poly(ethylene
oxide).sub.7 426 1.8 4 ethanol 18 Tergitol .RTM. C.sub.12-C.sub.14
secondary alcohol 728 1.8 3 15-S-12 (ethoxylate).sub.12 19 Tergitol
.RTM. C.sub.12-C.sub.14 secondary alcohol 596 4.4 3 15-S-9
(ethoxylate).sub.9 20 Witconol .RTM. TD-60 Tridecyl alcohol
(ethoxylate).sub.6 464 0 4 21 Witconol .RTM. NP-40 Nonylphenol
(ethoxylate).sub.4 396 0 4 22 Neodol .RTM. 1-9 C.sub.11 alcohol
(ethoxylate).sub.9 568 1.8 4 23 Neodol .RTM. 25-7 C.sub.12-15
alcohol (ethoxylate).sub.7-8 537 0 4 24 Brij .RTM. 97 poly(ethylene
oxide).sub.10 oleyl ether 708 0 4 *5 = water-like 0 = did not flow
immediately (possible Bingham plastic state)
EXAMPLES 25-36
[0072] Mixtures were prepared having the proportions shown in Table
IV below consisting of the milled and sieved ammonium sulfate
described in Example 1, propylene glycol (Fisher Scientific, 99.5%
assay) and dodecylphenoxy poly(ethyleneoxide).sub.9.5-11 ethanol
(Igepal.RTM. RC-630) surfactant. The suspensions were left
undisturbed for two days at room temperature after preparation with
thorough mixing. The syneresis percentage, pourability and
viscosity observations after two days are shown in Table IV. The
free liquid remained unchanged for each suspension after four
days.
[0073] The apparent viscosities of the suspensions were measured
using a Brookfield DV-E viscometer with an LV-4 spindle at 2.5 rpm
after stabilizing for 5 minutes. The LV-4 spindle is a straight
cylinder having a diameter of 3.15 mm. TABLE-US-00006 TABLE IV Wt.
% Wt. % Apparent Wt.. % ammonium propylene Igepal .RTM. Vol. %
Pourability Viscosity, Ex. No. sulfate glycol RC-630 Syneresis,
Rating poise 25 61.7 35.0 3.3 0 3 9360 26 61.5 34.9 3.6 0 3 9120 27
61.3 34.7 4.0 0 3 8880 28 61.1 34.6 4.3 0 3 7680 29 60.9 34.5 4.6 0
3.5 19400 30 60.7 34.4 4.9 0 3.5 13000 31 60.5 34.3 5.2 0 3.5 11000
32 60.3 34.2 5.5 0 3 9840 33 58.5 36.4 5.1 0 3.5 11040 34 55.9 39.3
4.8 <1 3.5 5760 35 58.4 36.3 5.4 <1 3 9840 36 55.7 39.2 5.1
<1 3 5520
[0074] Each of these suspensions of the invention showed excellent
stability, good pourability and moderate viscosity.
EXAMPLES 37-41
[0075] Mixtures were prepared ammonium sulfate, Igepal.RTM. RC-630
(dodecylphenoxy poly(ethyleneoxide).sub.9.5-11 ethanol) surfactant
and either ethylene glycol or propylene glycol. The ammonium
sulfate was the milled and sieved ammonium sulfate described in
Example 1. The ethylene glycol and propylene glycol were as
described in Comparative Example 2. The resulting suspensions had
the proportions shown in Table V below. The suspensions were left
undisturbed for four days at room temperature after preparation
with thorough mixing. The free liquid, and pourability after four
days were measured and are shown in Table V. TABLE-US-00007 TABLE V
Wt. % Ex. Wt.. % ammonium Wt. % Igepal .RTM. Vol. % Pourability No.
Glycol sulfate Glycol RC-630 Syneresis Rating 37 ethylene 59.3 36.9
3.8 0 3 38 ethylene 60.9 34.5 4.6 <1 2 40 propylene 59.3 36.9
3.8 0 4 41 propylene 58.9 36.6 4.5 0 4
[0076] Each of these suspensions of the invention showed excellent
stability and fair to very good pourability.
EXAMPLE 42-43
[0077] Two suspensions of the invention were prepared having
compositions of 59.1 wt. % ammonium sulfate, 4.2 wt. %
dodecylphenoxy poly(ethylene oxide).sub.9.5-11 ethanol (Igepal.RTM.
RC-630) and 36.7 wt. % glycol liquid. The glycol was ethylene
glycol in one suspension and propylene glycol in the other. The
ammonium sulfate was the milled and sieved material described in
Example 1. The ethylene glycol and propylene glycols were the same
materials described in Comparative Example 2.
[0078] 15.65 g of each suspension was transferred quickly (less
than 10 seconds) into a glass funnel of 60.degree. cone angle, and
having a stem of 4 mm inside diameter and of 60 mm length. The rate
at which a suspension was discharged from the funnel stem was
measured by means of a scale and time. The measurements are shown
in Table VI and are plotted recorded vs. discharge (culmulative
discharge/15.65) vs time in FIG. 1. The pourability ratings were 3
for the suspension in ethylene glycol and 4 for the suspension in
propylene glycol. TABLE-US-00008 TABLE VI Example 42 Example 43
Ammonium Sulfate Suspension In Ammonium Sulfate Suspension In
Ethylene Glycol Propylene Glycol Cumulative Cumulative Time, min
Discharge, g Time, min Discharge, g 1 0.79 2 2.70 3 2.01 3 4.00 5
3.1 4 5.50 7 4.26 5 6.70 9 5.38 6 8.00 11 6.65 7 9.30 13 7.69 8
10.60 15 8.83 9 11.70 17 9.91 10 12.70 19 10.99 11 13.60 21 11.96
12 14.20 23 12.49 13 14.20 25 13.87 27 14.3 29 14.3
EXAMPLES 44-45
[0079] Two suspensions of the invention were prepared having
compositions of 59.1 wt. % ammonium sulfate, 4.2 wt. %
dodecylphenoxy poly(ethylene oxide).sub.9.5-11 ethanol (Igepal.RTM.
RC-630) and 36.7 wt. % glycol liquid. The glycol was ethylene
glycol in one suspension and propylene glycol in the other. The
ammonium sulfate was the milled and sieved material described in
Example 1. The ethylene glycol and propylene glycols were the same
materials described in Comparative Example 2.
[0080] To test the rapidity of their dispersion and dissolution in
water, 1 ml of each suspension was injected from a syringe into 150
ml of tap water in a 250 ml beaker. The water was stirred by a
magnetic stir bar of 37 mm.times.9 mm dimensions rotating at about
200 RPM. As the suspensions were injected into the water, they
dispersed within about one second. The time to dissolve was
measured from the point of injection to the point where solid
particles could no longer be observed. The results were as follows:
TABLE-US-00009 TABLE VII Dissolving Time, Ex. No. Glycol in
Suspension sec 44 ethylene glycol 37 45 propylene glycol 24
EXAMPLES 46-47
[0081] The following examples illustrate suspensions of the
invention containing either a herbicide or a fertilizer. The
ammonium sulfate was the milled and sieved material described in
Example 1. The ethylene glycol was the same material described in
Comparative Example 2.
[0082] The other agricultural solids were RoundUp.RTM. DryPak
herbicide and diammonium phosphate (NH.sub.4).sub.2HPO.sub.4).
RoundUp.RTM. DryPak herbicid, manufactured by Monsanto Co, is the
isopropylamine salt of N-(phosphonomethyl) glycine. It is a member
of the class of herbicides known as glyphosates. The diammonium
phosphate was obtained from Fisher Scientific.
[0083] The RoundUp.RTM. DryPak and the diammonium phosphate were
separately ground in a small (.about.30 ml) SPEX Model 8000
Mixer/Mill using two 1/2 inch (1.27 cm) diameter stainless steel
balls. The ground solids were screened through a Tyler # 48 sieve.
Particles retained on the Tyler #48 sieve were discarded. A typical
particle size distribution for the ground and sieved solids is
listed in Table VIII. TABLE-US-00010 TABLE VIII Tyler Sieve Weight
% Retained No. on Sieve 48 0 60 6 80 15 100 31 200 13 400 19 pan
16
[0084] Suspensions of the invention were prepared each containing
59.1 wt. % total agricultural solids, 36.7 wt. % ethylene glycol
and 4.2 wt. % of dodecylphenoxy poly(ethylene oxide).sub.9.5-11
ethanol (Igepal.RTM. RC-630) surfactant. The suspensions, their
percent syneresis, and pourability ratings after 2 days of
undisturbed storage at room temperature are shown in Table IX.
TABLE-US-00011 TABLE IX Ex. Vol. % Pourability No. Solids
Composition Syneresis Rating 46 isopropylamine salt of 0 3
N-(phosphonomethyl) glycine 47
(NH.sub.4).sub.2SO.sub.4/(NH.sub.4).sub.2HPO.sub.4 - 67/33 0 4
(w/w)%
EXAMPLES 48-50
[0085] Three suspensions were prepared consisting of 59.1 wt. % of
the milled and sieved ammonium sulfate described in Example 1, 36.7
wt. % propylene glycol (Fisher Scientific, 99.5 % assay) and 4.2
wt. % dodecylphenoxy poly(ethylene oxide).sub.9.5-11 ethanol
(Igepal.RTM. RC-630) surfactant.
[0086] One of these suspensions was mixed with 0.3 wt. % of
methylthio-.alpha.-hydroxybutyric acid (chemical formula:
CH.sub.3SCH.sub.2CH.sub.2CH(OH)COOH). The
methylthio-.alpha.-hydroxybutyric acid was purchased from Aventis
Animal Nutrition, Alpharetta, Ga. in the form of an 88% aqueous
solution under the tradename Rhodimet.RTM. AT-88. A second one of
these suspensions was mixed with 0.6 wt. %
methylthio-.alpha.-hydroxybutyric acid. The third suspension was
left unchanged as a control
[0087] The suspensions were left undisturbed for six days at room
temperature after preparation. The syneresis percentage, and
pourability rating after six days are shown in Table X.
TABLE-US-00012 TABLE X Wt. % Vol. % Pourability Ex. No.
methylthio-.alpha.-hydroxybutyric acid Syneresis Rating 48 0 0 3 49
0.3 0 4 50 0.6 0 4
EXAMPLE 51
[0088] A suspension of the invention is prepared containing 59.1
wt. % ammonium sulfate, 36.7 wt. % propylene glycol, and 4.2 wt. %
dodecylphenoxy poly(ethylene oxide).sub.9.5-11 ethanol (Igepal.RTM.
RC-630). The ammonium sulfate is the milled and sieved material
described in Example 1. The propylene glycol is the same as
described in Comparative Example 2.
[0089] The suspension is dispersed and mixed in sufficient water to
bring the ammonium sulfate concentration down to 1 wt. %. Added to
this mixture is 1 wt. % of Monsanto Rodeo.RTM. brand glyphosate
herbicide (isopropylamine salt of N-(phosphonomethyl)glycine) to
form a herbicide/adjuvant spray solution.
[0090] Weed species grown in small pots are sprayed with this
solution at the rate of about 6 gallons per acre. This corresponds
to a doseage of about 0.5 lbs/acre of glyphosate and 0.5 lb/acre of
ammonium sulfate adjuvant. The weed species sprayed are Velvet
Leaf, Morning Glory, and Johnson Grass, known as difficult-to-kill
weeds. As a control, another group of the same weeds is sprayed
with a solution containing only glyphosate at a doseage of 0.5 lb
acre.
[0091] Fourteen days after the treatment the plants are cut off at
ground leveled and weighed. It is found that the new growth of the
weeds sprayed with the herbicide/adjuvant solution made from the
suspension of the invention is significantly less than the new
growth of weeds sprayed with the glyphosate solution.
* * * * *