High concentrated, solid mepiquat chloride products and processes for making dry form solid mepiquat chloride powder and tablets

The present invention provides hygroscopic plant growth regulator formulations in solid forms and associated methods of making the powders and tablets. The most preferred formulation uses an effective amount of an N,N-dimethyl-piperidinium salt.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to methods for making flowable, highly 
concentrated powders and tablets of hygroscopic plant growth regulator 
compounds, and more specifically to processes to dry mepiquat chloride 
aqueous solutions to form flowable highly concentrated solid products. 
2. Background of the Prior Art 
Plant growth regulators affect the physiology of plant growth and influence 
the natural rhythm of a plant. More specifically, plant growth regulators 
may, for example, reduce plant height, stimulate seed germination, induce 
flowering, promote or inhibit fog, darken leaf coloring, minimize lodging 
of cereals, slow grass growth on lawns, reduce boll rot and provide better 
boll retention in cotton. 
Plant growth regulators may be applied to plants in a variety of methods 
including different formulations. Of these various methods, use of liquid 
and dry compositions are the most common. The particular formulation 
desired and resulting efficacy enhancement will greatly depend upon the 
species to be treated, environmental conditions, the geographical area and 
the climatology of the area at the time of treatment. 
The plant growth regulator, known trivially as mepiquat chloride, is 
generally used to control various aspects of cotton boll growth. See, for 
example, Khafaga, Angew. Botanik 57, 257-265 (1983); Sawan et al., J. 
Agronomy & Plant Science, 154,120-128 (1985); U.S. Pat. Nos. 3,905,798 and 
4,447,255. 
Mepiquat chloride is used as a plant growth regulator in agriculture. 
Mepiquat chloride has a high water solubility of more than 600 g/L. The 
melting point is 223.degree. C. The substance is very hygroscopic when 
exposed to humid air. The substance is very hygroscopic, readily absorbing 
moisture from humid air, so much so, that the dry powder can turn to 
liquid when exposed to ambient humid air. During storage, the solid 
mepiquat chloride readily cakes and sticks to container surfaces, even at 
low residual water contents of less than 0.5%. 
These properties make it extremely difficult to dry mepiquat chloride. In 
conventional spray dryers, the material is very difficult to dry. It must 
be atomized extremely finely to reduce the moisture to a suitable level 
and even then it retains too much water to dry practically. The product 
remains sticky and adheres to the walls of the dryer and the dryer ducts 
and cyclones, eventually plugging the ducts and cyclones. Furthermore, 
powder from such a process, because it is so fine, flows poorly out of the 
dryer, and upon storage in a drum, is rendered unflowable due to caking. 
Solid forms of plant growth regulators offer a number of key advantages, 
including convenience, increased stability and shelf life, as well as 
reduced packaging, storage and shipping costs. Additionally, there is the 
possibility of future government regulation requiring solid forms of 
agricultural products in order to reduce handling of contaminated 
packaging of these products during field application and during disposal. 
These dry flowable plant growth regulating compounds would be safer for 
the farmer to use and dispose of, and also result in a smaller volume of 
hazardous waste being produced. 
There is a need for dry, flowable, highly concentrated powder and tablet 
formulations of hygroscopic plant growth regulators. 
SUMMARY OF THE INVENTION 
Surprisingly, a free-flowing, non-caking solid mepiquat chloride 
formulation can be achieved by mixing the solid hygroscopic plant growth 
regulator with finely divided, highly absorptive inerts. In such mixtures, 
concentrations of the plant growth regulator of up to about 99 percent by 
weight are achievable. When the mixtures of the invention are directly 
applied in a spray tank, the plant growth regulator dissolves instantly in 
the water without residues. 
The preferred plant growth regulators of the present inventions include the 
group consisting of 1,1-dimethyl-3,4-dehydropiperidinium bromide, 
4-chloro-1,1-dimethyl piperidinium bromide, 
1,1-dimethylhexahydropyridazinium bromide, and 1,1-dimethylpiperidinium 
chloride, also known as mepiquat chloride. 
It is an object of the present invention to provide an agriculturally 
acceptable hygroscopic plant growth regulator formulation in a solid form. 
It is a further object of the present invention to provide methods of 
making the solid form of hygroscopic plant growth regulator compositions 
of the present invention. 
It is another object of the present invention to provide an agriculturally 
acceptable hygroscopic plant growth regulator formulation in the form of a 
tablet. 
It is a further object of the present invention to provide methods of 
making the dry, flowable tablet form of hygroscopic plant growth regulator 
compositions of the present invention. 
These and other objects of the present invention will be more fully 
understood from the following description of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As used herein, the term "agriculturally acceptable" includes agricultural, 
industrial and residential use. 
As used herein, "plant growth regulator(s)" (hereinafter abbreviated as 
"PGR") or "regulation" includes the following plant responses: inhibition 
of cell elongation, for example reduction in stem height and internodal 
distance, strengthening of the stem wall, thus increasing the resistance 
to lodging; compact growth in ornamentals for the economic production of 
improved quality plants; promotion of better fruiting; increasing the 
number of ovaries with a view to stepping up yield; promotion of 
senescence of the formation of tissue enabling fruit to absciss; 
defoliation of nursery and ornamental bushes and trees for mail-order 
business in the fall; defoliation of trees to interrupt parasitic chains 
of infection; hastening of ripening, with a view to programming the 
harvest by reducing the harvest to one to two pickings and interrupting 
the food-chain for injurious insects. 
As used herein, PGR formulation of the present invention may be used to 
form both package and tank mix compositions. 
The present preferred invention comprises PGR compositions comprising an 
agriculturally and plant growth regulating effective amount of a 
hygroscopic PGR, and more preferably, an N,N-dimethylpiperidinium salt in 
a dry flowable highly concentrated powder. 
Preferred PGRs include salts of the formula: 
##STR1## 
where R is methyl or ethyl; X is the anion of an inorganic or organic, but 
not phytotoxic acid, preferably bromide or chloride, and A is a chain of 4 
or 5 methylene groups, which chain may be substituted by chloro, bromo, 
methyl, chloromethyl, bromomethyl, hydroxymethyl, and methylene, or which 
chain containing one or two double bonds, or A is the chain 
--(CH.sub.2).sub.n --NH--, where n is 3 or 4, disclosed in U.S. Pat. No. 
3,905,798 and hereby incorporated by reference. 
Preferred specific examples of PGRs include 
1,1-dimethyl-3,4-dehydro-piperidinium bromide, 
4-chloro-1,1-dimethyl-piperidinium bromide, 
1,1-dimethylhexahydropyridazinium bromide and 1,1-dimethyl-piperidinium 
chloride. The most preferred plant growth regulator is 
1,1-dimethyl-piperidinium chloride, also known as N,N-dimethylpiperidinium 
chloride or mepiquat chloride. This product is commercially available 
under the registered trademark Pix.RTM. (BASF AG, Germany). 
For convenience of description, mepiquat chloride will be used. However, 
the methods described apply equally to other hygroscopic PGRs. 
In a preferred embodiment, silica is injected in the inlet air stream of a 
spray dryer at a controlled rate. 
A spray dryer of the type illustrated in FIG. 1 may be used. As can be 
shown from FIG. 1, the aqueous PGR feed solution is agitated in a feed 
tank (2) and fed through a line (4) via a feed pump (6) into the spray 
dryer unit (8). The aqueous PGR feed solution is introduced into the spray 
dryer unit by an atomizing means (10). An inlet air heating means (12) 
provides heat to the dryer at a temperature of about 150.degree. to about 
250 degrees .degree.C. 
A flow aid such as silica is stored in a feed hopper (14) and injected into 
the spray dryer unit (8) via a screw feeder (16) through a line by an air 
eductor (18). The silica adheres to the forming droplets or partially 
dried particles formed by the aqueous mepiquat chloride feed solution in 
the vicinity of the atomizer (10) and reduces or eliminates the tendency 
of the partially dried mepiquat chloride particles from sticking to the 
spray drying unit walls (20, 22), the ducts (24), and the cyclone (26). 
The silica also renders the powder more flowable, eliminating caking in 
the drum even when stored for long periods of time provided the drum 
excludes ambient moist air. The flowing powder is then suitable for 
commercial tabletting or for filling water soluble bags. 
The rate at which the aqueous PGR feed solution is fed into the spray dryer 
unit is not critical and is dependent upon the size of the spray dryer 
used. This rate is easily determined by those skilled in the art. 
A preferred method dries the mepiquat chloride solution with a double drum 
dryer as illustrated in FIG. 2. The double drum dryer has a pair of 
hollow, rotating drums (28, 30) whose surfaces are scraped by a respective 
knife (32). High pressure steam is introduced to the interior of the drums 
and mepiquat chloride solution added continuously via a feed line (34) to 
the nip between the drums (36). The drums turn toward one another, by 
means of a conveyor, for example 38 depositing a portion of the liquid, 
boiling mepiquat chloride solution on the drum surface (28, 30) where 
boiling is initiated. Upon further rotation, the thin film of mepiquat 
chloride's water boils off into the vapor hood (40) and a solid film 
remains that is scraped by sharp knives (32) from the turning drum surface 
(28,30). The material is then collected and the flow aid is added to it to 
improve flowability and impart anti-caking properties prior to tabletting 
or filling water soluble bags. 
A preferred embodiment of the drying process utilizes a batch vacuum dryer 
with chopping blades which can also be described as a mechanical fluid 
bed. The most preferred batch vacuum dryer is a Littleford.RTM. type (or 
Lodige) vacuum dryer, as illustrated in FIG. 3. 
As is seen from FIG. 3, the vacuum dryer unit (50) consists of double 
jacket (42, 44). Inside the double jacket is a hollow rotating shaft (46) 
with attached plough shaped mixing elements (48). 
Aqueous PGR feed solution is fed via a line (50) into the vacuum dryer unit 
(52). Steam or hot water (54) is fed via a line (56) into a jacket (42) 
which surrounds the vacuum dryer unit (52), and optionally through the 
hollow rotating shaft (46). Agitating means (56) in the interior of the 
vacuum dryer unit (52) agitates the aqueous PGR feed solution. A vacuum 
means (58), which may be a pump or vacuum jet unit is introduced into and 
applied to the vacuum dryer unit (52). The vacuum and applied jacket heat 
causes the evaporation of the water from the aqueous PGR feed solution. 
The evaporated water boils up, passes through a bag collector means (60), 
and is recovered by a condenser (62) and collected in a condensate tank 
(64). 
When a sufficient amount of water has been evaporated, a paste begins to 
form. Mixing elements (48) are used to divide the paste, breaking it up, 
and bringing the interior moisture to the surface so as to expose it to 
the vacuum to increase the drying rate. As the material solidifies, the 
chopping means breaks the material into small particles to maintain the 
high drying rate. 
A free-flowing, non-caking solid mepiquat chloride formulation can be 
achieved by mixing the solid mepiquat chloride with a finely divided, 
highly absorptive inert flow aid such as silica. The addition of silica or 
other flow aid renders the powder flowable and non-caking, and suitable 
for tabletting or filling water soluble bags. The flow aid is introduced 
manually or mechanically through a port on or near the top of the drying 
chamber. 
All three drying processes use silica or other flow aid to improve 
flowability and prevent caking. These inert additives include any form of 
silica including fumed silicas, precipitated silicas, aluminum silicates, 
magnesium silicates, and the like, zeolites, bentoinites, 
montmorillonites, and attapulgites and mixtures thereof. The most 
preferred silica is commercially available as Sipernat.RTM. 50S. 
The weight of silica per weight of mepiquat chloride in all of these drying 
processes is about 0.2:100 to 3:100, and more particularly, about 2:100. 
Optionally, to further improve flowability, reduce sticking tendancy or 
caking, or to increase the dissolution rate, binders, fillers, and/or 
disintegrants can be dissolved in the feed solution before drying. 
Suitable binders, fillers, and/or disintegrants include water-soluble 
cellulose derivatives, cellulose derivatives, carboxymethyl cellulose, 
hydroxypropyl methylcellulose, water soluble gums such as gum arabic, gum 
tragacanth, alginates, gelatin, and polyvinylpyrollidone, cross-linked 
polyvinylpyrollidone, microcrystalline cellulose, modified starches such 
as sodium carboxymethyl starch, and mixtures thereof. 
Other suitable fillers, binders, and/or disintegrants include any water 
soluble starch, corn syrup, dextrin or pregelatinized starch which is at 
least partially soluble in water at ambient temperature. For example, 
there can be used as a binder the pregelatinized, modified and stabilized 
waxy maize starch which is marketed by the National Starch and Chemical 
Corporation under the trade name Instant Celar Gel. In addition, 
pregelatinized corn starch marketing by the Hubinger Company under the 
trade name OK Pre-Gel can be used. Other binders suitable for use are 
pregelatinized food starch, refined from tapioca and marketed under the 
trade name Instant Gel; stable, modified amylopectin marketed under the 
trade name Kosol; a low viscosity tapioca dextrin marketed under the trade 
name Crystal Gum; dextrinized corn starch marketed under the trade name 
Purity Glaze; maltodextrin marketed under the trade name Maltrin, such as 
M040 by Grain Processing Corporation. 
All of the above-described powders, with and without fillers, binders, 
and/or disintegrating agents can then be tabletted or filled into water 
soluble bags. Unexpectedly, the high potency powders which contain only 
the hygroscopic PGR active material and silica flow aid, tablet without 
aid of binders, fillers, and/or disintegrants, or lubricants on a 
commercial tablet press. The tablets formed are of commercial quality, 
having reproducible weight, sufficient tablet strength, and acceptable 
solubility. Water absorbance is minimal provided that the tablets are made 
in a dehumidified room. The tablets can be dissolved and passed through a 
50 mesh screen such as that found on spray equipment without residue. 
While the ratios of the concentrations of the various components of the 
present invention hereinafter suggested, those skilled in the art will 
recognize that minor variations may be necessary to accommodate particular 
characteristics of acceptable plant growth regulators which may be 
employed in this invention. 
In general, the formulations of the present invention contain from about 
0.1 to about 99.8%, and preferably from about 95 to about 99% by weight of 
active ingredient. 
Typically, for a plant growth regulator concentrate of the present 
invention, the concentration of regulator active ingredient will be at 
least 0.0125 pints/acre. 
In such mixtures, concentrations of mepiquat chloride up to about 99 
percent by weight are achievable. When the mixtures of the invention are 
directly applied in a spray tank, the mepiquat chloride dissolves 
instantly in the water and this spray solution passes a 50 mesh screen of 
the spray equipment without residues. 
The tablets can be manufactured by compressing the mixtures on tablet 
machines. Also for tabletting, other inert ingredients like disintegrants, 
binders, fillers, and/or disintegrants, wetting agents or lubricants can 
be blended with the PGR mixture. (Optionally, the wetting agents and 
lubricants can be incorporated by addition in the drying step-either into 
the PGR liquid solution before drying, or can be added with the inert flow 
aid during drying.) 
When the tablets are dropped into the water of the spray tank, the mepiquat 
chloride is quickly dissolved and this spray solution passes a 50 mesh 
screen of the spray equipment without residues. 
In addition to the above-described components, the compositions of the 
present invention may also include other ingredients or adjuvants commonly 
employed in the art. 
Examples of such ingredients include drift control agents, defoaming 
agents, preservatives, surfactants, fertilizers, phytotoxicants, 
herbicides, pesticides, insecticides, fungicides, wetting agents, 
adherents, nematocides, bactericides, trace elements, synergists, 
antidotes, mixtures thereof and other such adjuvants well known in the 
plant growth regulator art. 
However, it is preferred to employ the compositions of the present 
invention along with sequential treatments with these other components for 
optimal effect. 
The compositions of the present invention may be applied to plants. The 
application of liquid and particulate solid plant growth regulator 
compositions to above ground portions of plants may be carried out by 
conventional methods, for example, boom and hand application, including 
sprayers or dusters. The composition may be applied aerially as a spray, 
if desired. The mixtures of the present invention are preferably used in 
the form of aqueous solutions. The mixtures are applied in a conventional 
manner, for example, by spraying, atomizing, watering or disinfecting 
seed. 
The forms of application depend entirely on the purpose for which the 
compositions are being used. In any event, they should ensure a fine 
distribution of the active ingredients in the composition. 
The above plant growth regulator formulation may then be dispersed in water 
and sprayed onto plants according to the method of the present invention. 
Powders, dusts and broadcasting agents may be prepared by mixing or 
grinding the active ingredients with a solid carrier. 
Granules, for example, coated, impregnated or homogeneous granules, may be 
prepared by bonding the active ingredients to solid carriers. Examples of 
solid carriers are mineral earths such as silicic acid, silica gels, 
silicates, talc, kaolin, Attaclay, limestone, lime, chalk, bole, loess, 
clay, dolomite, diatomaceous earth, calcium sulfate, magnesium sulfate, 
magnesium oxide, ground plastics, fertilizers such as ammonium sulfate, 
ammonium phosphate, ammonium nitrate, and ureas, and vegetable products 
such as grain flours, bark meal, wood meal, and nutshell meal, cellulosic 
powders, and the like. 
The action of the compositions of the present invention are optimal even at 
low application rates. For a given plant growth regulator composition, the 
skilled artisan will readily arrive at a composition having the optimum 
ratio of the ingredients by routine experimentation. 
The compositions of this invention may be prepared, for example, by adding, 
in any order, the various components of the composition of the present 
invention. For example, one may start with a commercial formulation of 
mepiquat chloride, which is an aqueous concentrate containing 0.35 pounds 
per gallon of mepiquat chloride (4.2%) by weight. Thereafter, in any 
order, one mixes suitable amounts of any optional adjuvants or 
ingredients. 
The following examples serve to illustrate the invention and should in no 
way be construed as limiting the scope thereof. 
EXAMPLES 
Example 1--Formulation 
An aqueous solution of mepiquat chloride was dried to give a solid mepiquat 
chloride with a water content of 0.2%. This product was not free flowing 
and caked in a sealed, tight container after 2 days of storage at room 
temperature. 
Directly after drying, 198 g solid mepiquat chloride were mixed with 2 g of 
Aerosil.RTM. 200 in a laboratory mixer to give a homogeneous mixture. 
After storage in a sealed container for 1 month at room temperature and 
50.degree. C., there was no caking. The mixture remained free flowing. 
Twenty grams of the mixture were poured into a laboratory spray tank 
filled with 1 gallon tap water at room temperature. The mepiquat chloride 
dissolved completely within 1 minute. There was no residue on a 100 mesh 
screen of the laboratory spray tank. 
Example 2--Water Soluble Bag 
One hundred grams of the mixture described in Example 1 were packaged using 
a water soluble film (Monosol.RTM. M7030). This water soluble bag was 
dropped into a spray tank filled with 25 gal. tap water at room 
temperature. The water was circulated through a 50 mesh screen. The 
mepiquat chloride and the film of the bag dissolved completely within 10 
minutes. These was no residue on the 50 mesh screen. 
Example 3--Tablet Formulation 
Ninety-five grams of the mixture described in Example 1 and 5 g 
Divergan.RTM. F were blended in a laboratory mixer. A 15 g tablet, 21/2 
in. (5.7 cm) diameter, was made with a hand operated hydraulic press. The 
tablet was dropped into a spray tank with tap water at room temperature. 
The tablet broke up completely and the mepiquat chloride dissolved within 
10 minutes. There was no residue on the 50 mesh screen of the spray tank. 
Example 4--Formulation 
Directly after drying as described in Example 1, 294 g solid mepiquat 
chloride were mixed with 6 g Sipernat.RTM. 50S in a laboratory mixer to 
give a homogeneous mixture. After storage in a sealed container for 1 
month at room temperature and 50.degree. C., there was no caking. The 
mixture remained free flowing. 
Twenty grams of the mixture were poured into a laboratory spray tank filled 
with 1 gal. tap water at room temperature. The mepiquat chloride dissolved 
completely within 1 minute. There was no residue on the 100 mesh screen of 
the laboratory spray tank. 
Example 5--Water Soluble Bag 
One hundred grams of the mixture described in Example 4 were packaged using 
a water soluble film (Mono Sol.RTM. M8532). This water soluble bag was 
dropped into a spray tank filled with 25 gal. tap water at room 
temperature. The water was circulated through a 100 mesh screen. The 
mepiquat chloride and the film dissolved completely within 10 minutes. 
These was no residue on the 100 mesh screen. 
Example 6--Tablet Formulation 
Using the mixture of Examples 4, 20 g tablets, 21/2 in. (5.7 cm) diameter, 
were made with a hand operated hydraulic press. Five tablets were dropped 
into a spray tank filled with 25 gal. tap water at room temperature. The 
tablets broke up completely and the mepiquat chloride dissolved within 12 
minutes. There was no residue on the 100 mesh screen of the spray tank. 
Example 7--Formulation 
A 600 g/L solution of mepiquat chloride was placed in an agitated, 
jacketed, spray dryer feed tank and heated to 65.degree. C. with tempered 
water. The heated solution was pumped at 125 g/min to an atomizing wheel 
rotating at about 17,000 rpm in a Niro Utility spray dryer. Silica 
(Sipernat 50S) from a loss-in-weight screwfeeder was injected via an air 
eductor into the air plenum to mix with the heated air entering the 
plenum. The silica was fed at a rate of 4% based on the dry basis feed 
rate of the mepiquat chloride solution. The silica/air mixture, at 
200.degree. C., then entered the drying chamber, intermixing with the 
droplets formed by the atomizer. The resultant outlet temperature is about 
140.degree. C. On drying the powder exits the drying chamber does not 
adhere to the walls of the spray dryer, the ducting, or the cyclone 
separator. The powder remains flowable in a polyethylene bag packed in a 
sealed plastic drum. 
The resulting powder was flowable, had a moisture content of 0.25%, a bulk 
density of 0.29 g/ml untapped, 0.38 g/ml tapped, and an ash content of 
about 2%. The powder assayed at about 97% mepiquat chloride. 
Example 8 
Steam at 105 psig was introduced to a lab scale double drum dryer and the 
rolls rotated at about 5 rpm. Mepiquat chloride liquid was fed from a 
reservoir to the nip of the rolls at a rate of about 36 g/minute. The 
material adhered to the rolls and the moisture was evaporated while the 
drums rotated. The solid film was scraped off the rolls by a blade and 
collected. Material collected without silica rapidly caked. Material that 
was collected and mixed with about 2% (Sipernat 50S) silica did not cake 
and was flowable. The moisture content was about 1.2% in the resultant 
powder, with a density of 0.25 g/ml untapped and 0.35 g/ml tapped. 
Example 9 
To a 130 liter Littleford "mechanical fluid bed" dryer (Model FKM-130 with 
chopping blade), 171.6 lbs of mepiquat chloride 600 g/L aqueous solution 
was charged. The agitator plough was started at 155 rpm, and 15 psig steam 
introduced to the jacket. A vacuum was pulled with a vacuum pump, 
maintaining 600 mm Hg at the pump. The evaporated vapors passed through a 
bag filter and were condensed using a cold glycol/water mixture on the 
shell side of a condenser. The resulting condensate was collected in a 
receiver. As evaporation continued, the amperage drawn by the plough motor 
began to rise. The chopper blades were turned on, and the drying 
completed. During this time the steam pressure on the jacket was 
progressively increased to drive off the water from the forming paste. As 
more water was removed, the paste turned to solid, the chopper greatly 
increasing the rate of drying by dividing moist material and exposing the 
interior moisture to the vacuum and hot dryer walls. When water was no 
longer being removed, the dried solid was cooled by applying cool water to 
the jacked of the apparatus. Approximately 2% of silica was then added to 
the material and allowed to blend. When this mixing operation was 
complete, the finished product was discharged to a drum. 
The resulting free flowing powder was composed of particles ranging from 
approximately 5 to 60 microns in diameter, with a moisture of about 0.08%, 
and bulk density of 0.63 untapped and 0.79 tapped, and ash content of 
about 2%. The powder assayed at about 97% mepiquat chloride. There was no 
detectable mepiquat chloride in the overhead condensate. 
Example 10 
About 10 pounds of powder made by the method in Example 9 was charged to 
the feed hopper of a single station Stokes R excenter tablet press located 
in a low humidity room. The relative humidity of the room remained about 
28% between 70.degree. and 80.degree. F. The press was fitting with 
tooling to make 2.25 inch diameter tablets. After pressure and size 
adjustments, tablets were made of about 21 grams with good tablet 
integrity. Hardnesses, as measured on a RIMAC tester, were 15 to 21 lbs 
force. Tablets were found to have picked up less than 0.3% moisture during 
this operation. 
The tablets had thicknesses of about 0.8 to 0.9 centimeters. The tablets 
dissolved under mild agitation in water in about 7 to 9 minutes and the 
resulting liquid did not deposit any residue when passed through 150 
micron sieve (100 mesh). 
Whereas particular embodiments of the invention have been described above 
for purposes of illustration, it will be appreciated by those skilled in 
the art that numerous variations of the details may be made without 
departing from the invention as described in the appended claims. 
Example 11 
A mepiquat chloride powder prepared by the method of (example 8 for drum 
dryer) was tabletted in a Carver press. Press pressure was varied at 6 to 
7 metric tons, 8 to 9 metric tons, and 10 to 11 metric tons for durations 
of 1 minute each. The formed tablets, of 2.26 inches in diameter, had 
thicknesses between 0.24 and 0.26 inches with weights of between 15.3 to 
15.6 gms, with breaking strengths between 9 and 22.3 lbs as determined on 
a modified Chatilion electronic tester, model DFI-50 mounted on a model 
LTC manual test stand. The tablets were dissolved in 750 ml of 342 ppm 
hardness water stirred with a magnetic stirring bar and dissolved 
completely in 0.9 to 4.7 minutes. 
Example 12 
A mepiquat chloride powder prepared by the method of (example 9 for the 
Littleford dryer) was tabletted in a Carver press. Press pressure was 
varied at 8 to 9 metric tons, and 10 to 11 metric tons for durations of 1 
minute each. The formed tablets, of 2.26 inches in diameter, had 
thicknesses between 0.24 and 0.26 inches with weights of between 15.3 to 
15.7 gms, with breaking strengths between 17 and 32 lbs as determined on a 
modified Chatilion electronic tester, model DFI-50 mounted on a model LTC 
manual test stand. The tablets were dissolved in 750 ml of 342 ppm 
hardness water stirred with a magnetic stirring bar and dissolved 
completely in 4.4 to 5.8 minutes. 
Example 13 
A mepiquat chloride powder prepared by the method of (example 7 for the 
spray dryer) was tabletted in a Carver press. Press pressure was varied at 
6 to 7 metric tons, 8 to 9 metric tons, and 10 to 11 metric tons for 
durations of 1 minute each. The formed tablets, of 2.26 inches in 
diameter, had thicknesses between 0.23 and 0.28 inches with weights of 
between 14.4 to 15.7 gms, with breaking strengths between 16.5 and 55 lbs 
as determined on a modified Chatilion electronic tester, model DFI-50 
mounted on a model LTC manual test stand. The tablets were dissolved in 
750 ml of 342 ppm hardness water stirred with a magnetic stirring bar and 
dissolved completely in 3.8 to 4.8 minutes. 
Whereas particular embodiments of the invention have been described above 
for purposes of illustration, it will be appreciated by those skilled in 
the art that numerous variations of the details may be made without 
departing from the invention as described in the appended claims.