A method for producing storage stable ureaform dispersion fertilizers by: reaction of urea and monomethylolurea in aqueous solution at a pH between 3.0 and 4.5 with a temperature between 25.degree. and 75.degree. C. until between 15 and 40 percent of the total nitrogen has been converted to form a dispersion of finely divided water insoluble ureaform particles; neutralizing; and admixing a water-insoluble, film-forming oil until the dispersed ureaform particles are coated with sufficient oil to prevent contact between the ureaform particles and the aqueous solution. The water insoluble, film-forming oils found effective include fatty acids, fatty acid esters, castor oil, castor oil esters, alkoxylated castor oils, and alkoxylated alkyl phenols. The amount of film-forming oil required to coat the ureaform particles is between 0.1 and 1.0 percent of the aqueous ureaform dispersion. To prevent settling of the coated ureaform particles a xanthan gum, or iota carrageenan thickener is added.

BACKGROUND OF THE INVENTION 
This invention relates to an improved method for the preparation of a 
ureaform dispersion fertilizer, and the product resulting therefrom. More 
particularly it relates to a new method for preparing ureaform dispersion 
fertilizers from urea and monomethylolurea which are stable in soluble 
fertilizer salt solutions. 
Liquid fertilizers are usually aqueous solutions of salts of ammonium, 
potassium, phosphate, and nitrate ions which frequently contain dissolved 
urea. In recent years liquid fertilizers have been developed which contain 
dispersed insoluble ureaform particles to lengthen the period of time over 
which the nitrogen content is released as a plant nutrient. 
Ureaform is a term which is used in the fertilizer art to denote mixtures 
of urea-formaldehyde polymers. The overall water solubility of these 
polymers is low thereby precluding its releasing nitrogen at a rate high 
enough to burn or damage vegetation. Ureaform polymers may be indicated by 
analysis for water insoluble nitrogen (WIN) according to the method 
reported in Official Methods of Analysis of the Association of Official 
Agricultural Chemists, 11th Edition, 1970. WIN is used herein to denote 
quantitatively the amounts of insoluble ureaform solids. Some water 
soluble low molecular weight urea-formaldehyde methylene compounds are 
also ureaform compounds by virtue of chemical structure. 
Ureaform is usually produced by the acid catalyzed reaction of urea and 
formaldehyde, or urea and urea-formaldehyde concentrates. The reaction is 
also catalyzed at a slower rate by the presence of acid or alkali ions 
even in neutral aqueous solutions. The ureaform reaction can continue 
until virtually all of the formaldehyde moieties are converted to high 
molecular weight water insoluble ureaform solids. Stopping the conversion 
of ureaform at a desired level of conversion to water insoluble solids, so 
that appreciable amounts of the ureaform compounds remain as readily 
available nitrogen nutrients for plants has been the object of much of the 
urea-formaldehyde fertilizer art. The further reaction of ureaform solids 
with urea and water soluble urea-formaldehyde compounds must be 
substantially stopped to produce a storage stable ureaform dispersion 
fertilizer. The ionic content of the dispersion aqueous liquids catalyzes 
this further reaction and makes the required stabilization very difficult. 
Heretofore the efforts made at stabilization have been to change the 
chemical structure of the ureaform solids. 
Techniques which have been used include: drying to eliminate the catalytic 
effects of the ionic components of a ureaform solution; introduction of 
extraneous moieties such as sugars or higher aldehydes into the polymer 
chains; and caping the polymer chains with moieties which inhibit or stop 
further polymerization, such as ammonia, amines, or alcohols. Another 
technique used has been to prepare the insoluble ureaform in two stages; 
the first being carried out at relatively high temperatures and high 
formaldehyde to urea ratios to form methylene and methylene urea polymers; 
and the second being reaction with additional urea at lower temperatures. 
Ureaform dispersion fertilizers offer an effective and safe method for 
supplying nutrients to turf and ornamental and commercial crops. A 
ureaform dispersion fertilizer may be defined as a flowable fertilizer 
containing urea-formaldehyde compounds and polymers, a substantial portion 
of which are water insoluble solid particles, dispersed throughout the 
fertilizer. 
The production of a liquid ureaform fertilizer containing water insoluble 
nitrogen was disclosed in U.S. Pat. No. 3,677,736 by Richard E. Formaini. 
A liquid dispersion fertilizer containing ureaform having at least 1.5 
percent WIN was produced by acidifying to a pH below 5, a dilute 
urea-formaldehyde reaction product, and heating to a temperature between 
30.degree. and 80.degree. C., and neutralizing. Prior to acidifying, 
Formaini heated the urea-formaldehyde mixture under neutral, or basic, 
conditions until 60 percent of the formaldehyde was in the methylene form. 
In U.S. Pat. No. 4,033,745, William P. Moore discloses the stabilization of 
ureaform fertilizer dispersions by utilization of alcohol and sugars as 
polymer caping moeities to stabilize the ureaform. 
Paul Sartoretto et al disclosed in U.S. Pat. No. 4,298,512 aqueous 
dispersions of urea-aldehyde polymers for use as liquid fertilizers. The 
urea-aldehyde polymers are primarily ureaform, modified by the inclusion 
of one or more alkyl aldehydes containing from two to four carbon atoms. 
Even though Sartoretto recommends the use of urea-formaldehyde concentrate 
plus expensive and difficult to handle acetaldehyde or propionaldehyde, 
the reaction mixture is still quite exothermic and difficult to control. 
Urea-formaldehyde concentrate is a partially reacted mixture usually 
containing about 60 percent by weight formaldehyde, 25 percent urea, and 
the remainder water. Sartoretto states that when formaldehyde is reacted 
with urea the urea formaldehyde dispersions formed are unstable because 
polymerization and cross-linking apparently continue even at neutral pH, 
the solids becoming aggregated and lacking in dispersibility. 
In U.S. Pat. No. 4,409,015 Thomas T. Grace discloses a two-stage process 
for preparing an aqueous dispersion fertilizer containing ureaform WIN, 
wherein he teaches reaction in the first stage of 2.5 to 4.7 mols 
formaldehyde with 1 mol of urea at about 90.degree. C. in the presence of 
an acid condensation catalyst until methylene and methyleneurea polymers 
have been formed of the desired length. These polymers are indicated by a 
special methanol solubility test indicating the intermediate to be 
storable for one year. Then, in the second stage the intermediate is 
reacted with an additional amount of urea by means of an acid catalyst 
until the amount of WIN is in the range of 15 to 35 percent of the total 
nitrogen of the system. Grace teaches substantially deactivating the 
formaldehyde in the first stage so that the reaction is less exothermic 
and easier to control in the second stage where the WIN is formed. The 
dispersion fertilizer product from the second stage has a preferred urea 
to formaldehyde mol ratio of 1.1 to 1.7 to 1. Grace further teaches the 
use of dicyandiamide to enhance the stability of the dispersion fertilizer 
by reacting with aldehyde groups present, presumably caping the WIN 
polymers. 
Total nitrogen contents ranging between 15 and 18 percent by weight, and 
preferably 16 to 16.5 percent, are prescribed by Grace with the WIN 
preferably between 20 and 30 percent of the total nitrogen. No 
quantitative specification of, or reference to, unreacted urea contents 
are provided in U.S. Pat. No. 4,409,015. However, it is known that where 
methylene groups exist, particularly as polymethylene chains or methylene 
urea, the amount of additional urea which can be reacted is significantly 
lower than with non-polymerized urea and formaldehyde, or 
monomethylolurea. Liquid ureaform dispersion fertilizers are used 
commercially for turfgrasses, ornamental plants, and foliar feeding crops 
in areas which are long distances from locations of possible manufacture 
so that storage stability and concentration are important factors in the 
costs of shipping, and in the ultimate utility of the product. Maximum 
concentrations of previously disclosed liquid dispersion fertilizers are 
about 18 percent by weight. If one were to ship the highly storable first 
stage intermediate of U.S. Pat. No. 4,409,015, its shipping cost per unit 
of nitrogen would be high because its nitrogen content is only about 10 
percent by weight. 
It has long been an object of those skilled in the art to produce a 
ureaform dispersion fertilizer where the maximum amount of urea is 
protected per formaldehyde moiety used in a simple process generating 
little heat, from raw materials which are high in nitrogen concentrations 
and economical to ship and store. 
It is therefore an object of this invention to provide a method of 
preparing a storage stable ureaform dispersion fertilizer containing 
economically significant amounts of water insoluble nitrogen (WIN). 
It is a further object of this invention to provide an easily controlled 
method of reacting urea to ureaform dispersion fertilizers using minimum 
amounts of formaldehyde moieties. 
It is another object of this invention to provide a ureaform dispersion 
fertilizer which does not solidify or settle during extended periods of 
storage. 
It is still another object to provide a ureaform dispersion fertilizer 
which may be blended with other plant nutrients, such as phosphate and 
potash to form storage stable complete liquid fertilizers. 
SUMMARY OF THE INVENTION 
I have found that a storage stable ureaform dispersion fertilizer can be 
prepared in an easily controlled method, whereby urea is reacted with 
monomethylolurea in acid solution to form a dispersion of finely divided 
water insoluble ureaform particles, the acid is then neutralized, and a 
water insoluble, film-forming oil is admixed to coat the dispersed 
ureaform particles with sufficient oil to prevent contact between the 
particles and the aqueous solution, thereby preventing catalysis of 
further reaction of the solids by the acid ions in the aqueous solutions. 
The dispersion fertilizer containing the oil protected ureaform particles 
may be blended with thickeners to prevent settling of the particles or 
blended with other plant nutrient salts to produce complete liquid 
fertilizers and stored without further reaction of the ureaform solids. 
According to the present invention, a method for producing a storage stable 
ureaform dispersion fertilizer comprises five steps listed as follows: (1) 
admixing between 1 and 3 mols of urea per mol of monomethylolurea in water 
to form an aqueous solution containing between 10 and 20 percent total 
nitrogen by weight; (2) acidifying the aqueous solution to a pH between 
3.0 and 4.5 by admixing a mineral acid; (3) maintaining the acidified 
solution at a temperature between 25.degree. and 75.degree. C. until the 
urea and monomethylolurea have reacted sufficiently to form a dispersion 
of water insoluble ureaform particles containing between 15 and 40 percent 
of the total nitrogen of the acidified solution; (4) neutralizing the 
aqueous dispersion to pH 6.5 to 7.5 by admixing an acid neutralizing 
material; and (5) admixing a water insoluble, film-forming oil with the 
aqueous dispersion until the dispersed ureaform particles are coated with 
an amount of oil sufficient to prevent contact between the ureaform 
particles and the aqueous solution. 
DETAILED DESCRIPTION OF THE INVENTION 
The method of the present invention employs five stages which may be 
carried out in a rather simple reaction vessel which would normally be 
equipped with a centrifugal circulating pump and a heat exchanger through 
which the reaction mixture is circulated. No special, or unusual, 
equipment is required because of the simplicity of the method. The 
agitation and mixing provided by an effective circulating pump is usually 
sufficient although a mechanical mixer and a jacketed reaction vessel may 
also be effectively used. 
The reaction of monomethylolurea with free urea was found to be the most 
effective method for utilizing formaldehyde moieties to convert the 
maximum amounts of urea to ureaform compounds. For example, when a 
two-stage method is used to condense formaldehyde and urea by first 
forming methylene-methylene urea polymers at high formaldehyde to urea 
ratios, and then reacting with additional urea to form a ureaform liquid 
containing about 25 percent of its nitrogen as WIN, at an overall urea to 
formaldehyde moiety ratio of 1.7, the free urea amounted to 38 percent of 
the total nitrogen content of the dispersion fertilizer. Using the same 
moiety ratio and simply reacting monomethylolurea with urea to convert 25 
percent of the total nitrogen, free urea amount to only 22 percent of the 
total nitrogen. The undesirable free urea was thus reduced by 42 percent 
while maintaining the same WIN. 
Monomethylolurea and urea may be admixed with water as pure chemical or 
technical compounds. They may also be prepared "in-situ" by reaction of 
urea and formaldehyde so long as the methylolurea and urea are formed in 
the desired mol ratio and in the concentrations required to produce the 
necessary total nitrogen content. It is also necessary that other 
methylene and methylol compounds amount to less than 10 percent by weight 
of the nitrogen. 
Surprisingly, mechanically isolating the ureaform particles by coating them 
with a layer of water insoluble oil was found to be effective in 
preventing the further reaction of those ureaform molecules to form high 
molecular weight polymers which can form molecular networks throughout the 
liquid to such an extent that it becomes quite viscous, or it completely 
solidifies. Besides preventing the physical degradation of the ureaform 
liquids, the small amount of oil coating used in the method of the present 
invention prevents further polymerization to produce polymers which have a 
low nutrient availability. 
For the method of this invention to be effective in producing a storage 
stable ureaform dispersion fertilizer it is necessary that the five steps 
be performed as defined in the following paragraphs. 
First, between 1 and 3 mols of urea per mol of monomethylolurea must be 
mixed in water to produce an aqueous solution containing between 10 and 20 
percent total nitrogen by weight. It was found that less than 1 mol of 
urea per mol of monomethylolurea, produced a dispersion fertilizer which 
was low in availability to plants, and when more than 3 mols of urea was 
used per mol of monomethylolurea, the free urea in the ureaform product 
was high enough to cause some burning of foliage when applied to bluegrass 
in hot, dry weather at normal rates of 1 pound N/1000 ft.sup.2. To convert 
appreciable amounts of a 20.sup.+ percent total nitrogen solution, for 
example, 25 to 35 percent, was found to produce a dispersion fertilizer 
which was too viscous to handle effectively. Those viscous liquids were 
almost like solids at typical fall and spring ambient temperatures. When 
nitrogen contents were lower than 10 percent by weight, it was difficult 
to produce stable suspensions of the ureaform particles. The method 
performed best when between 1.3 and 1.7 mols of urea per mol of 
monomethylolurea were mixed in water to form an aqueous solution 
containing between 14 and 18 percent total nitrogen. It was found that 
dimethylol-, and trimethylolurea did not perform well in this invention. 
They behaved about like urea-formaldehyde concentrate by exothermically 
reacting with urea in a manner difficult to control, forming water 
insoluble ureaform particles having poor storage stability. 
Second, it is necessary to acidify the aqueous solution to a pH between 3.0 
and 4.5 by adding and mixing a mineral acid. Although mineral acids were 
generally effective in that pH range, best results were obtained when pH 
was held between 3.8 and 4.2 by using nitric, sulfuric, phosphoric, 
superphosphoric or hydrochloric acid, or mixtures of them. Nitric acid was 
effective and provided a small amount of desirable nitrate in the 
dispersion fertilizers. Likewise, the sulfuric and phosphoric acids also 
provided desirable nutrients. 
Third, it is necessary to maintain the acidified solution at a temperature 
between 25.degree. and 75.degree. C. until the urea and monomethylolurea 
have reacted sufficiently to form a dispersion of water insoluble ureaform 
particles containing between 15 and 40 percent of the total nitrogen of 
the acidified solution. At temperatures below 25.degree. C. the ureaform 
reaction rate was found to be too slow for commercial practicality and at 
temperatures above 75.degree. C., the ureaform solids formed were high 
polymers having low plant nutrient availability. Preferred reaction 
temperature was found to be 45.degree. to 55.degree. C. which allowed a 
practical reaction time to form an aqueous dispersion of water insoluble 
ureaform particles containing between 20 and 30 percent of the total 
nitrogen of the acidified solution. 
Fourth, after maintaining the acid reaction conditions it is necessary to 
neutralize the dispersion to a pH of 6.5 to 7.5 by adding and mixing a 
base, and the stability of the product was improved further when pH was 
held between 6.8 and 7.2. The bases found most effective were ammonia, 
alkali metal hydroxides, alkali metal carbonates, alkaline earth oxides, 
alkaline earth carbonates, and alkanolamines. 
Fifth, it is key to the success of the method of this invention to add to 
the dispersion of water insoluble ureaform particles, a water insoluble, 
film-forming, oil and to mix it until the particles are coated with 
sufficient oil to substantially prevent contact between those suspended 
ureaform particles and the aqueous solution which contains the ions which 
act as a catalyst to continue the reaction to form low availability, high 
molecular weight ureaform polymers. To be effective the oils must be 
capable of forming a continuous, thin, water insoluble film over the 
surface of the insoluble ureaform particles which substantially prevent 
the passage of aqueous ions, such as phosphate, sulfate and nitrate. If 
large amounts of oil were required, the system would be unsuitable because 
the oil could cause plant phytotoxicity, application problems, and poor 
economics. 
Drying oils were found to be ineffective because they allowed passage of 
the catalyst ions and subsequent increases in viscosity and solidification 
after relatively short storage periods. To prevent these coating oils from 
sinking to the bottom or rising to the surface of the liquid it was 
necessary that their specific gravity be between 0.9 and 1.2. To 
facilitate the complete coating of the ureaform solids it was found 
necessary that the pour point of the oil be between -30.degree. and 
0.degree. C. 
Coating oils found to be particularly effective were fatty acids, fatty 
acid esters, castor oil, alkoxylated castor oils, castor oil esters, and 
alkoxylated alkylphenols. These particular coating oils were found to have 
a special affinity for the dispersed ureaform particles and effectively 
coated them. Their speed of coating the particles was enhanced by addition 
of nonionic surfactants. Cationic or anionic surfactants were unsuitable, 
causing polymerization and destabilization of the fertilizer dispersion. 
The coating oils need not be chemically pure compounds. The chemical 
compound comprising a large portion of castor oil is glyceryl 
trihydroxyoleate. Fatty acid compounds found to be suitable comprised 
commercial grades of ricinoleic acid, oleic acid and hydroxyoleic acid. 
Castor oil esters found suitable comprised commercial grades of methyl 
ricinoleate, butyl ricinoleate, and glyceryl triacetyl ricinoleate. The 
alkoxylated castor oils found useful in the present invention included 
commercial grades of ethoxylated ricinoleic acid containing from 1 to 6 
mols ethylene oxide per mol of ricinoleic acid. When more than 6 mols of 
ethylene oxide is included, the water solubility of the coating oil is too 
high, allowing the passage of the reaction catalytic ions to the surface 
of the ureaform particles. Alkoxylated castor oil which contains between 1 
and 6 mols of propylene oxide is as effective as the ethoxylated castor 
oil. 
Alkoxylated alkylphenol compounds which were found to perform as effective 
coating oils included nonylphenol alkoxylated with between 3 and 8 mols of 
ethylene or propylene oxide per mol of nonylphenol. 
For successful performance of the method of this invention it is necessary 
to accurately admix small amounts of the coating oil. It was found that 
satisfactory stabilization of the ureaform dispersion fertilizer could be 
obtained with oil amounting to between 0.05 and 1.00 percent by weight of 
the aqueous ureaform dispersion. Further, it was found that the addition 
of a small amount of nonionic surfactant, between 0.02 and 0.08 percent, 
to the coating oil increases the speed of its coating of the dispersed 
ureaform particles. 
Although their use is not required in the method to produce stable ureaform 
dispersion fertilizers, addition of thickening agents to the dispersions 
of this invention drastically decreases the rate of settling of the 
oil-film coated ureaform particles to the point where they stay suspended 
in a substantially homogeneous dispersion for periods of three to six 
months. It was found that the thickener could be added to the dispersion 
prior to the admixing of the coating oil, and that method was preferable, 
when a surfactant was added with the oil, to preclude foaming when the 
thickener was mixed with the dispersion. 
Thickening agents do not take part in protecting the dispersed ureaform 
from further reaction, but simply increase viscosity in the dispersion to 
reduce settling rates. Although settling of the ureaform particles coated 
with the oil film does occur in several days, the particles remain stable, 
do not agglomerate, and may be resuspended by gentle agitation. 
Thickening agents found to be particularly effective in suspending the oil 
coated ureaform particles dispersion fertilizers were iota carrageenan, 
and xanthan gum. The amounts of these agents required for effective use in 
this method were low, with larger amounts required where dispersed 
ureaform particles comprised less than 3 percent by weight nitrogen. When 
those particles amounted to more than 7 percent, very low thickener 
concentrations were required because of the inherent viscosity of the 
dispersion. The range of thickener concentrations which were found to 
perform satisfactorily in the method of this invention was between 0.03 
and 1.00 percent by weight of the dispersion fertilizer, and preferably 
between 0.06 and 0.10 percent. 
Iota carrageenan is a high molecular weight extract from Rhodophyceaea (Red 
Algae). It contains repeating galactose units joined by 1-3, and 1-4 
glycosidic linkages and has a molecular weight between 100,000 and 
500,000. It is marketed under the trade name Gelcarin-DG by FMC 
Corporation. 
Xanthan gum is a high molecular weight natural carbohydrate, specifically a 
polysaccharide, and may be defined as an exocellular biopolysaccharide 
produced in a pure culture fermentation process by the microorganism 
Xanthomonas Campestris. Xanthan gum is marketed under the trade name of 
Kelzan by Merck and Company. 
When the ureaform particles were coated with the oil film, the ureaform 
dispersion, which is essentially a nitrogen fertilizer, could be converted 
to a complete fertilizer by adding other nutrients without destroying the 
dispersion stability. Although phosphate, and potassium plant nutrients 
are used in the form of nearly neutral salts, they ionize to form ions in 
aqueous solution which would ordinarily catalyze the further 
polymerization of ureaform dispersions during storage to solidify the 
liquid dispersion, unless the dispersed particles are protected. Potassium 
chloride, potassium sulfate, potassium phosphate, diammonium phosphate, 
monoammonium phosphate, and ammonium polyphosphate were added to the 
ureaform dispersions of this invention to form liquid suspension 
fertilizers frequently produced and stored for use in the custom lawm 
treating industry. Analyses of these fertilizers prepared included: 
14%N-3%P.sub.2 O.sub.5 -6%K.sub.2 O and 16%N-3%P.sub.2 O.sub.5 -3%K.sub.2 
O. 
It was found that an aqueous ureaform dispersion could be prepared by the 
method of this invention which was very effective as a liquid fertilizer 
for application to turfgrass on the soil and foliage and as a foliar feed 
for commercial and ornamental plants.

The best mode of operating the present invention is described in greater 
detail in the specific examples which follow. In these examples all 
temperatures are in degrees Celsius and all parts and percentages are by 
weight unless stated to be otherwise. 
EXAMPLE 1 
To a round bottom flask equipped with an electric heating mantle, a 
magnetic stirrer, a thermometer, and openings for a pH electrode and for 
the addition of materials were added ingredients in the amounts listed as 
follows: water, 440 grams; monomethylolurea, 388 grams; and urea, 172 
grams. The liquid mixture was hazy when it was blended and cooled to a 
temperature of 15.degree. C. Concentrated sulfuric acid was diluted with 
distilled water to produce a 10 percent sulfuric acid concentration. This 
acid was added until the pH of the well-mixed liquid was 4.0. Heat was 
then applied with the heating mantel until temperature of the liquid 
reached 50.degree. C. 
Agitation was continued for 90 minutes while temperature was maintained at 
50.degree. C. with alternating air cooling of the flask, and electrical 
heating. The pH of the liquid was maintained at 4.0 throughout the 90 
minute period of reacting the urea and monomethylolurea. During the early 
part of the reaction period, the liquid was clear, but it started to cloud 
after about 45 minutes. The liquid had a creamy white appearance caused by 
the presence of finely divided, water insoluble ureaform particles. During 
the reaction period, no temperature rises were observed, and at the end of 
the period, pH was adjusted to 7.0 by the dropwise addition of aqueous 20 
percent potassium hydroxide, and the temperature of the reaction mixture 
was reduced to 23.degree. C. by removing the heating mantle from the flask 
and replacing it with a water bath. 
While agitation of the aqueous ureaform dispersion was continued with the 
magnetic stirrer, 1 gram of castor oil was added and agitation was 
continued until the ureaform particles were evenly coated with the castor 
oil. The dispersion fertilizer was sampled and stored in closed bottles. 
Analyses showed the total nitrogen content to be 19.7 percent. The total 
water insoluble nitrogen (WIN) content was 4.7 percent and the hot water 
insoluble nitrogen (HWIN) content was 0.8 percent. Free urea nitrogen 
content was 5.7 percent, and the water soluble methylene urea nitrogen 
calculated by difference was 9.3 percent. 
The retained samples were shaken for 30 seconds and viscosity was 
determined by a Brookfield viscosimeter at 20.degree. C. and 25 rpm to be 
85 centipoise. When the samples were stored, some settling occurred after 
7 days and about half of the liquid was clear after 2 months storage. When 
the samples were shaken lightly after 2 months storage, the coated 
ureaform particles were easily evenly re-dispersed throughout the liquid 
with no solids remaining on the bottom of the container. Viscosity was 
determined to be 88 centipoise. The same redispersal was done after 6 
months storage and the viscosity was found to be 84 centipoise, indicating 
that the ureaform particles were storage stable and that they were not 
reacted or polymerized further. Analysis on the stored product was again 
performed after 6 months storage, with total nitrogen amounting to 19.8 
percent, WIN 4.8 percent, and HWIN 0.8 percent, further confirming the 
storage stability of the ureaform dispersion. 
EXAMPLE 2 
A 200 gram sample of the freshly prepared product from Example 1 was 
retained. To this sample was added 0.1 gram of iota carrageenan, purchased 
commercially as Gelcarin-DG. The mixture was stirred with the magnetic 
stirrer for 30 minutes and the Brookfield viscosity at 20.degree. C., 
measured at 20 rpm was found to be 160 centipoise. The stabilized ureaform 
dispersion fertilizer showed no sign of settling after 6 months storage 
and viscosity was 175 centipoise. The WIN remained 4.8 and the HWIN was 
0.8 percent. 
EXAMPLE 3 
To a 15,000 gallon capacity stainless steel tank equipped with an external 
heat exchanger for heating with steam and cooling with water, a 
centrifugal pump for recirculating, an agitator, a temperature sensor and 
recorder, an in-line pH meter, and nozzles for introducing fluids, was 
added 13,830 lbs water and 26,915 pounds of a buffered commercially 
marketed solution, containing 30% N and 2% K.sub.2 O, comprising 
monomethylolurea and urea, having a composition as follows: 
______________________________________ 
Component Wt % 
______________________________________ 
Monomethylolurea 47.1 
Methylenediurea 1.9 
Urea 30.0 
Ammonia 1.0 
Potassium bicarbonate 
4.2 
Water 15.8 
______________________________________ 
The mol ratio of urea to monomethylolurea in the reactor charge was 1.05 
and the nitrogen concentration was 19.8 percent. Into the circulating 
aqueous monomethylolurea and urea, nitric acid at 55 percent concentration 
was added. Carbon dioxide effervesced from the solution until the pH had 
decreased below 5. Nitric acid addition was continued until the pH was 
decreased to 3.6, and amounted to 3825 lbs. Steam was applied to the 
systems heat exchanger to increase the temperature of the reaction mixture 
to 60.degree. C. The temperature was maintained at 60.degree. C. for 30 
minutes with very little cooling. During this reaction period, the pH 
tended to increase so that an additional 2055 lbs of 55% nitric acid was 
added to maintain pH between 3.6 and 4.0. The clear initial reaction 
mixture started to cloud after about 10 minutes and had a creamy white 
consistency after 30 minutes, when the pH was brought to 6.7 by 
introducing 1415 lbs of 45 percent potassium carbonate solution. Aqueous 
50 percent urea was added, amounting to 1850 lbs while maximum cooling was 
applied at the same time to bring the temperature down to 25.degree. C. 
To the resulting aqueous dispersion of ureaform solids was added 50 pounds 
of xanthan gum (Kelzan by the Kelco Division, Merck, Inc.) through an 
eductor located on the inlet side of the centrifugal circulating pump. 
After allowing 15 minutes for the hydration and blending of the xanthan 
gum thickener, 2 lbs of the commercial nonionic surfactant Citowett, 
produced by BASF, was added. To the resulting mixture 60 lbs of commercial 
oleic acid was added as a water insoluble film-forming coating oil, and 
allowed to mix for 15 minutes to coat the surfaces of the dispersed 
ureaform particles. 
The product was pumped to a storage tank, sampled and analyzed. Total 
nitrogen content was 17.9 percent, free urea was 5.9 percent, nitrate N 
was 0.9 percent, WIN was 4.6 percent, and HWIN was 1.4 percent. Potassium 
content was 1.9 percent as K.sub.2 O. Viscosity of the product pumped to 
storage was 210 centipoise. 
A 50-gallon drum of the product was retained as a sample and the remainder 
was used commercially as a low burn fertilizer for lawns, after being 
blended with water, ammonium polyphosphate, and potassium chloride to form 
a 14-3-3 liquid concentrate. 
After 3 months storage the material from the 50-gallon drum contained 4.7 
percent WIN and 1.4 percent HWIN, and viscosity was 225 centipoise. There 
was no separation of the coating oil. 
EXAMPLE 4 
To a stirred stainless steel reaction tank, equipped with a recirculating 
pump, temperature indicator, and a pH probe, was charged 2025 pounds of 
the same commercial monomethylolurea and urea solution used in Example 3 
and 1000 pounds of water. Agricultural grade green phosphoric acid 
(0-54-0) was added to reduce the pH from an initial level of 9.6 to 4.0. 
CO.sub.2 effervescence occurred until a pH of about 5 was reached. The 
amount of acid required to bring the pH down was 435 pounds. Live steam 
was then injected directly into the reaction mixture until temperature of 
the agitated mixture reached 57.degree. C. in 7 minutes. The mixture was 
then allowed to react for 21 minutes with the pH varying from 4.0 to 4.5, 
with 48 pounds additional phosphoric acid added in two additions to keep 
pH below 4.6. No cooling was used during the reaction period, and the 
temperature increased slightly to 62.degree. C. At the end of the reaction 
period, the pH was brought to 6.8 by the addition of 155 pounds of 
potassium carbonate. Virtually no temperature change was observed during 
the neutralization. Significant CO.sub.2 effervescence was observed. Water 
amounting to 1120 pounds, 155 pounds of potassium chloride, and then 1044 
pounds prilled urea were added, quickly cooling the reaction mixture to 
38.degree. C. The reaction product was a light gray colored dispersion. 
Iota carrageenan (Gelcarin-DG) thickener amounting to 1.8 pounds was 
blended into the reaction mixture. 
To the stirred, thickened, ureaform dispersion was added 3.6 pounds of 
glyceryl monoricinoleate (marketed as Flexrin 13 by Cas Chem, Inc.) and 
1.0 pound of a nonionic surfactant (Cittowett marketed by BASF). After the 
mixture was stirred 15 minutes to assure complete coating of the dispersed 
ureaform particles, the product was sampled and stored. 
Analyses showed the product to initially contain 18.8% total N, 3.3% WIN, 
1.3% HWIN, 4.2% P.sub.2 O.sub.5, and 3.6% K.sub.2 O. Viscosity was 110 
centipoise. The stored product was used as a low burn, long lasting 
dispersion fertilizer for injection around the roots, and as a foliar feed 
for vegetables. The retained sample after 3 months had a viscosity of 140 
centipoise and the analyses were substantially unchanged. 
EXAMPLE 5 
The product from Example 3 (analyzing 17.9% N-0% P.sub.2 O.sub.5 -1.9% 
K.sub.2 O) was blended with ammonium polyphosphate solution (10-34-0) and 
soluble potassium chloride (0-0-62) to produce a complete fertilizer 
concentrate comprising 14% N-3% P.sub.2 O.sub.5 and 3% K.sub.2 O. This 
concentrate was stored for 3 months with the ureaform particles remaining 
substantially dispersed, with viscosity increasing slightly from 210 
centipoise to 225 centipoise during that period. 
The concentrate was diluted with water until the nitrogen concentration was 
decreased to 4 percent. The dispersed ureaform particles remained stable, 
but they settled out after about 1 hour. They were re-dispersed by mild 
agitation. 
The diluted dispersion fertilizer was applied to bluegrass turf at the rate 
of 1 lb N per 1000 ft.sup.2 and gave a good increase in grass vitality 
with no burn or damage to the foliage.