Solid compositions of a pyrazolium salt, urea and a liquid surfactant

There are provided solid herbicidal compositions comprising a molecular solution of a liquid, non-ionic surfactant, a 1,2-dimethyl-3,5-diphenylpyrazolium salt and urea in one another. There is also provided a method for preparing said compositions which comprises the steps of melting together the components of the composition at elevated temperatures and then cooling said melt.

The present invention relates to a solid, three component herbicidal 
composition comprising a molecular solution of a liquid, non-ionic 
surfactant, such as octylhenoxy polyethoxy ethanol, or nonylphenoxy 
polyethoxy ethanol, a 1,2-dimethyl-3,5-diphenylpyrazolium salt and urea, 
in one another. The invention further relates to a method for preparing 
the aforementioned ternary composition which comprises melting the 
components of same together, and then cooling said melt. 
As it is known, 1,2-dimethyl-3,5-diphenylpyrazolium salts can be formulated 
as concentrated aqueous solutions useful as herbicidal compositions. 
Unfortunately, such solutions of 1,2-dimethyl-3,5-diphenylpyrazolium 
salts, especially the methylsulfate, tend to deposit some of the herbicide 
in a crystalline form when stored for a period of time, especially when 
exposed to a cold environment. Once partial crystallization has occurred, 
such concentrates have to be heated and agitated in order to redissolve 
the deposited solids before they can be used for the preparation of dilute 
aqueous sprays. Similarly, conventional solid compositions containing said 
pyrazolium toxicants and the desired surfactants usually result in soft, 
and at times, oily products with poor flow properties which are not 
entirely suitable for agricultural use. 
In general, the above solid herbicide-urea-surfactant compositions which 
are characterized as free flowing powders and soluble in water, can be 
prepared in a straightforward manner as hereinbelow set forth. 
A suitable surfactant, namely, octylphenoxy polyethoxy ethanol, or 
nonyl-phenoxy polyethoxy ethanol, is heated to 90.degree. C. or above. To 
the latter are next added the herbicide, 
1,2-dimethyl-3,5-diphenylpyrazolium salt, preferably the methylsulfate, 
and urea, and the mixture stirred and heated until a homogeneous solution 
is obtained. The molten mixture is then poured or sprayed on a cold 
surface, where it rapidly congeals. If so desired, the above molten 
mixture may be sprayed into a cold, gaseous environment, wherein the 
individual droplets of said spray congeal while in free flight, and are 
collected as a fine powder. The solidified composition is quite hard and 
has an amorphous, sometimes crystalline appearance. In this state, the 
above compositions may be converted to granules, beads, prills, flakes and 
the like, with commercially available equipment. Alternatively, the above, 
molten mixture may be extruded into various shapes by commercially 
available hot-melt extruders. 
Advantageously, the sequence steps of heating, mixing and melting the 
components of the hereinabove described compositions together are not 
critical. Thus, equally good results may be obtained by melting the 
herbicidal salt or the urea first, and then adding the remaining 
components in any order desired, followed by stirring and heating the thus 
obtained mix until a homogeneous melt is obtained. 
The solid particles of the herbicide urea composition obtained by the above 
process are free-flowing, dry and relatively non-hygroscopic. These 
compositions, especially when particulated, are readily soluble in cold 
water. An additional advantage of the present compositions is that the 
particles shaped therefrom, when packed in containers do not form lumps or 
cake-up upon storage. 
Flowability of the above particles of said compositions may be further 
increased by coating said particles with about 1% to 5%, by weight, and 
preferably from 1% to 3%, by weight, of a solid lubricating agent, such as 
a fumed synthetic silica or a precipitated silica with a particle-size 
range of between 0.015 microns and 2 microns. 
The liquid, non-ionic surfactant, referred to hereinabove as "octylphenoxy 
polyethoxy ethanol" has an average molecular weight of 628 and contains an 
average of 9 to 10 ethylene oxide units, representing 67%, by weight, of 
said surfactant. The specific gravity of this surfactant is 1.065 at 
25.degree. C.; the viscosity is 240 cps at 25.degree. C. (Brookfield; 12 
r.p.m.), and the flash point is &gt;300.degree. F. (TOC). While the liquid 
non-ionic surfactant, referred to as "nonylphenoxy polyethoxy ethanol" 
contains an average of 9 ethylene oxide units, representing 66% by weight 
of said surfactant, the specific gravity of this surfactant is 1.06 at 
25.degree. C., the viscosity is 224-300 cps at 25.degree. C., and the 
flash point is &gt;200.degree. F. 
In practice, dilute aqueous sprays of the above compositions are used to 
control undesirable weed species in the presence of agronomic crops. 
Alternatively, the compositions of the present invention may be prepared as 
follows: from about 10% to about 30%, by weight, and, preferably, from 13% 
to 27%, by weight, (of the composition) of octylphenoxy polyethoxy ethanol 
is heated to a temperature range of from about 90.degree. C. to about 
160.degree. C. and, preferably, from 125.degree. C. to 128.degree. C. To 
the above heated surfactant is added from about 33% to 64%, by weight, of 
1,2-dimethyl-3,5-diphenylpyrazolium methylsulfate, and from about 4% to 
about 57%, by weight, and, preferably, from 9% to 54%, by weight, of urea 
to adjust the overall composition to 100%, by weight. After the addition 
is completed, the resultant mixture is stirred and heated at the 
temperature range specified above, for a period of time sufficient to 
obtain a homogeneous melt, usually from about 0.5 hour to about 5 hours. 
Resultant melt may be used directly in a hot-melt extruder to form various 
shapes, or may be poured or sprayed on a cold surface where it congeals. 
The melt may be sprayed into a cold gaseous environment, wherein the 
individual droplets of said spray congeal while in free flight. The 
thus-obtained solid may then be formed, if desired, into flakes, granules, 
beads, prills and the like, by commercially available equipment. The 
present composition in its final shape is free-flowing, dry and 
essentially nonhygroscopic. The flowability of the above particles of said 
composition may further be improved by coating same with about 1% to 5%, 
by weight, and, preferably, from about 1% to 3%, by weight, of a solid 
lubricating agent, such as a fumed synthetic silica or a precipitated 
silica having a particle-size range of from 0.015 micron to 2 microns. 
The above-described solid compositions may also be prepared by pre-blending 
all components of said composition at room temperature and then subjecting 
said blend to the above melt-cool process. 
The 1,2-dimethyl-3,5-diphenylpyrazolium salts of the present compositions 
are known. For instance, they have been disclosed in U.S. Pat. No. 
3,882,142, issued on May 6, 1975 to Walworth et al. Their use as 
herbicides has been disclosed in U.S. Pat. No. 3,922,161, issued on Nov. 
25, 1975 to Walworth et al. 
The hereinabove-defined compositions are eminently suitable for the 
postemergence control of undesired plant species, especially wild oats in 
the presence of crops such as wheat, barley, and rye, when applied at a 
rate of from 0.56 to 3.36 kg per hectare of active cation.

The present invention is further illustrated by the following examples. 
EXAMPLE 1 
Preparation of a solid composition consisting of a pyrazolium herbicide, a 
surfactant and urea 
Octylphenoxy polyethoxy ethanol (367.74 g; 27% by weight of composition) is 
heated to 150.degree. C., then 1,2-dimethyl-3,5-diphenylpyrazolium 
methylsulfate (871.68 g; 64% by weight of composition) is added in small 
increments with stirring, and then the mixture stirred at 
150.degree.-158.degree. C. until a clear solution occurs. Next, urea 
(122.58 g; 9.0% by weight of composition) is added and stirring of the 
mixture continues until a homogeneous melt is formed. The molten mixture 
is poured into aluminum pans and allowed to solidify. 
A portion of the solidified product is ground in a micropulverizer, while 
another portion of the product is coarsely ground to pass through a 10 
mesh screen. Samples of both are stored at 55.degree. C. for 3 days, after 
which neither sample shows visible physical changes in appearance, 
flowability and solubility. 
The freshly prepared composition contains 63.46% by weight of 
1,2-dimethyl-3,5-diphenylpyrazolium methylsulfate. A sample stored at 
45.degree. C. for one month assays 63.46% by weight, and a sample stored 
at 45.degree. C. for two month assays 62.91%, by weight, of the above 
herbicide. 
EXAMPLE 2 
Evaluation of the effect of the temperature of melting on the 
herbicide-surfactant-urea composition 
A. Octylphenoxy polyethoxy ethanol (492 g; 24.6% by weight of composition) 
is heated to 140.degree. C. and 1,2-dimethyl-3,5-diphenylpyrazolium 
methylsulfate (1308 g; 65.4% by weight of composition) is added at once. 
Next, urea (200 g; 10% by weight of composition) is added and the mixture 
heated at 140.degree.-155.degree. C. for 4 hours with intermittent 
stirring. Resultant solution (2000 g) is poured into an aluminum cooling 
pan, and when solidified, is ground. The composition contains 63.81%, by 
weight, of 1,2-dimethyl-3,5-diphenylpyrazolium methylsulfate. 
B. The preparation under A is repeated, except that the sample is heated at 
160.degree.-170.degree. C. for 4 hours. On cooling in the aluminum pan a 
few crystals form in the composition, but the bulk of it remains a tarry, 
tacky mass. The material is not analyzed. 
C. Octylphenoxy polyethoxy ethanol (369 g; 24.58% by weight of composition) 
is heated to 90.degree. C., then 1,2-dimethyl-3,5-diphenylpyrazolium 
methylsulfate (491 g) is added and the whole stirred until a thin slurry 
is obtained. Next, urea (150 g; 10% by weight of composition) is added, 
the temperature of the mixture raised to 120.degree. C. and then a second 
portion of 1,2-dimethyl-3,5-diphenylpyrazolium methylsulfate (491 g; a 
total of 982 g; 65.42% by weight of composition is used) is added and the 
whole heated at 125.degree.-128.degree. C. for 5 hours. A sample removed 
from the melt approximately 30 minutes after start analyses for 64.62%, by 
weight, of 1,2-dimethyl-3,5-diphenylpyrazolium methylsulfate, while the 
rest of the preparation assays 64.76%. 
A sample (43 g) is spread out on a large petri dish and exposed to the 
environment (with daily variations in ambient temperature and relative 
humidity). The sample shows a 0.9 g (2.1%) weight gain in 10 days. 
EXAMPLE 3 
Preparation of a herbicide-fertilizer-surfactant composition 
Octylphenoxy polyethoxy ethanol (52.8 g; 13.2% by weight of formulation) is 
heated to 155.degree. C., then 1,2-dimethyl-3,5-diphenylpyrazolium 
methylsulfate (133.6 g; 33.4% by weight of formulation) is added slowly 
and the mixture stirred until a clear solution occurs. Next, urea (213.6 
g; 53.4% by weight of formulation) is added and the mixture stirred until 
a homogeneous melt is formed. The melt is poured into an aluminum cooling 
pan, and when solidified is ground to 10 mesh. 
EXAMPLE 4 
Preparation of a flaked herbicide-surfactant-urea composition 
A 45.36 kg (100 lbs) batch of a composition comprising: 65.4% by weight of 
1,2-dimethyl-3,5-diphenylpyrazolium methyl sulfate (98%), 24.6% by weight 
of octylphenoxy polyethoxy ethanol and 10.0% by weight of urea is prepared 
by method C for Example 2 and loaded into the heated reservoir of a 
rotating drum type of flaking machine. While in the reservoir the batch is 
kept fluid by maintaining its temperature at about 110.degree. C. 
A slowly rotating heated drum (6 r.p.m; 45.degree.-48.degree. C.) 
continuously picks up on its surface a film of the above molten 
composition from the reservoir (a flat pan). The thickness of the film is 
then adjusted with a pinch roller from about 0.79 mm. to about 1.58 mm 
(1/32" to 1/16"). The slowly solidifying, but still pliable film of 
composition, is then shaved off from the drum with a doctor blade, and 
falls into a storage bin. While in free flight, the material cools off and 
fully solidifies, and fractures into individual flakes, partially while 
still in flight and partially upon impacting in the storage bin. 
The above described composition of Example 4 can also be flaked by using a 
commercially available steel belt flaking-cooling machine. 
EXAMPLE 5 
Preparation of a pan granular formulation of a herbicide-surfactant-urea 
composition 
Employing the molten composition of Example 4, granulation is attained by 
using a pan granulation (agglomeration) machine, such as the HOT MELT 
GRANULATION.TM. equipment manufactured by FERRO-TECH Company of Detroit, 
Mich. 
EXAMPLE 6 
Postemergence Herbicidal Activity 
The postemergence herbicidal activity of the composition of the present 
invention is demonstrated by the following tests, wherein wild oats are 
treated with compositions both of a conventional formulation and the 
formulation of Example 1, in the presence of wheat and barley. In the 
tests, seedling plants are grown in separate cups for about two weeks. The 
test formulations are dissolved in water in sufficient quantity to provide 
the equivalent of about 0.125 kg to 4.0 kg per hectare of active cation 
when applied to the plants through a spray nozzle operating at 2.81 
kg/cm.sup.2 pressure for a predetermined time. After spraying, the plants 
are placed on greenhouse benches and are cared for in the usual manner, 
commensurate with conventional greenhouse practices. Five weeks after 
treatment, the seedling plants are examined and rated according to the 
rating system provided below. The data obtained are reported in Table I 
below. 
TABLE I 
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RATING SYSTEM 
% CONTROL 
RATING (COMED TO CHECK) 
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9 - Complete kill 100 
8 - Approaching complete kill 
91-99 
7 - Good herbicidal effect 
80-90 
6 - Herbicidal effect 
65-79 
5 - Definite injury 
45-64 
4 - Injury 30-44 
3 - Moderate effect 
10-29 
2 - Slight effect 6-15 
1 - Trace effect 1-5 
0 - No effect 0 
______________________________________ 
The above rating scale is based upon visual observation of plant stand, 
vigor, malformation, size, chlorosis, and overall plant appearance as 
compared with a control. 
______________________________________ 
Plant Species 
______________________________________ 
WO = Wild oat (Avena Fatua) 
E = Wheat, Era (Triticum aestivum c.v. Era) 
W = Wheat, Waldron 
(Triticum aestivum c.v. Waldron) 
BY = Barley, Steptoe 
(Hordeum vulgare) 
______________________________________ 
TABLE I 
__________________________________________________________________________ 
Evaluation of the postemergence wild oat herbicidal activity of the 
invention, as compared to conventional formulations. 
Conventional 
64% real, 32% real, 
Rate formulation Composition of Ex. 1 
Composition of Ex. 1 
kg/ha WO E W BY WO E W BY WO E W BY 
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4.0 9 5 6 1 9 5 6 1 9 5 6 3 
2.0 9 5 7 0 9 5 7 0 9 3 7 0 
1.0 9 3 6 0 9 0 5 0 9 3 6 0 
0.5 9 0 5 0 9 0 5 0 9 1 5 0 
0.25 9 0 3 0 8 0 0 0 8 0 3 0 
0.125 6 0 1 0 6 0 0 0 7 0 1 0 
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