Chemistry: fertilizers – Processes and products – Inorganic material
Reexamination Certificate
2001-01-18
2002-07-23
Sayala, Chhaya D. (Department: 1761)
Chemistry: fertilizers
Processes and products
Inorganic material
C071S054000, C071S058000, C071S059000, C071S064130, C504S116100
Reexamination Certificate
active
06423109
ABSTRACT:
INTRODUCTION AND BACKGROUND
The present invention relates to a process and compositions for producing a free flowing fertilizer which exhibits enhanced deposition and anti drift characteristics.
More particularly, the process of the present invention relates to controlling the particle size of the fertilizer to a range which is more course than a fine powder but finer than unprocessed material, spraying onto the presized fertilizer a liquid deposition agent, blending until homogeneous, and post adding other agents such as defoamers, anticaking agents, other deposition enhancement agents, surface active agents, dispersing agents, crystalline inhibitor agents, other sequestering agents, shear resistant anti drift agents and the like and screening out oversized particles if necessary.
The use of fertilizers such as ammonium sulfate to enhance herbicide and pesticide performance is well documented. The need for deposition enhancement and resistance to drift is also well documented. Prior efforts have been made to address these issues. For example, guar as a deposition enhancement component for fertilizer compositions has been suggested in U.S. Pat. No. 5,964,917. The use of polyacrylamide suspensions/emulsions as a deposition enhancement agent for tank mix applications is also known, see U.S. Pat. Nos. 5,550,224; 5,824,797 and 5,874,096. The above patents are relied on and incorporated herein for the disclosure of the polyacrylamide polymers.
To be able to combine the effectiveness of a polyacrylamide suspension/emulsion deposition enhancement agent with fertilizer components such ammonium sulfate would be a desirable feature.
Incorporating a liquid deposition agent onto a fertilizer component presents obstacles to overcome such as tackiness of the mixture, caking in the bag, scaling of the liquid deposition agent with the fertilizer resulting in particles which will not disperse readily in the spray tank or deactivation of the deposition agent and other agents.
Other desirable components that can be incorporated into fertilizer compositions include but are not limited to defoaming agents, surface active agents, potentiating agents, dispersing agents, crystalline inhibitor agents, other dry deposition/anti drift agents, other sequestering agents, shear resistant anti drift agents, and the like.
Polyacrylamides have been used in dry fertilizer mixtures. Sanitek Products has a product known as 41A—FG(Fine Grind) which is a dry milled polyacrylamide mixture with xanthan gum. See U.S. Pat. Nos. 4,510,081 and 4,610,311. These two patents are relied on for the disclosure relating to the polyacrylamide polymers. This product is easy to use in dry systems but is effective only at high concentrations. The polyacrylamide must be ground to a fine particle size to overcome tank mixing problems. When the polyacrylamide dry particles are hydrated, if they are not very small initially, they will swell to form “fish eyes” which can block in line screens and nozzles resulting in pressure buildup in the system and spotty spray patterns. When the polyacrylamide particles are ground to a fine size, a significant reduction in anti drift/deposition efficiency is noted requiring the use of much higher concentrations to achieve adequate control.
Agricultural pesticides prior to spraying often benefit from specific additives to the spray mix which provide functionality that is either not possible or practical as commercial pesticide formulations. These functionalities include but are not limited to the sequestering of antagonistic metal ions found in the water used for spraying or as micronutrients added to the tank to correct soil deficiencies, improved target deposition, reduction of off target drift, foam control, increase in droplet drying time to allow additional absorption time, decreased surface tension/wetting, improved absortion and the like.
Off target drift and enhanced deposition of pesticide containing spray droplets has been an industry issue for many years. This issue has been magnified with the advent of the Biogenetic Era. It is now a common event to spray a powerful herbicide such as glyphosate onto crops such as soybeans which have been genetically engineered to resist damage by glyphosate. At the time of spraying it is not unusual to have glyphosate sensitive crops such as corn growing nearby. Without using good drift management techniques, it is possible to injure or kill young growing corn plants with off target drift containing glyphosate.
Off target drift effects performance of pesticides as the portion which drifts away is not effective on the proper target. This loss of pesticide activity impacts the farmer negatively with reduced crop yields. Therefore, it is desirable to reduce off target drift of the spray mist while enhancing proper deposition onto the intended target. The deposition enhancement effect of droplet adhesion has been studied extensively within the industry. When spray droplets hit the intended target, it is desirable for them to hit and stay on the target rather than to bounce off. The anti bounce effect is related to droplet size and also to droplet elasticity. The greater the retention of the droplet on the target, the more efficient the droplet is in having its intended pesticidal effect.
It is generally considered within the industry that the optimum size of the spray droplet to minimize off target drift while enhancing proper deposition is in the 200 to 400 micron range. Droplets smaller than 150 microns are highly susceptible to drift. Droplets larger than 400 microns represent reduced coverage and therefore reduced pesticide efficiency.
An object of this invention is to provide a convenient and easy-to-use fertilizer composition which offers improved resistance to off-target drift as well as improved deposition onto the desired target.
Another object of the invention is to provide optionally additional functionality such as enhanced sequestering of metal ions found in the water used for spraying or added to the spray mix to correct soil deficiencies, effective foam control, decrease in evaporation rate, decreased surface tension/wetting times, and as a result improved pesticide activity.
SUMMARY OF THE INVENTION
The above and other objects of the invention can be achieved by a combination of dry milled polyacrylamide and a liquid polyacrylamide emulsion/suspension plus other functioning agents for applications to a properly sized solid fertilizer.
Traditional polyacrylamide dry systems are very sensitive to shear and show substantially reduced performance as the tank mix is recirculated through the pumping system. By combining the mixture of a dry milled polyacrylamide with a polyacrylamide emulsion/dispersion, differing rates of hydration from the different systems are used to extend the time of control under different shear rates through the pumping system.
Incorporation of other shear resistant polymers can further extend the time of activity under shear stress.
DETAILED DESCRIPTION OF THE INVENTION
According to a feature of the invention, the free-flowing fertilizer of the invention is comprised of the following:
i) from 25 to 99.5% by weight of a powdered water soluble nitrogen containing fertilizer such as ammonium sulfate, urea, ammonium nitrate, potassium nitrate, diammonium phosphate.
ii) from 0.05 to 1.5% by weight of a polyacrylamide liquid emulsion/dispersion such as Percol E 38 from Ciba Specialties containing a high molecular weight nonionic or anionic polymer
iii) from 0.1 to 3.0% by weight of a polyacrylamide powder whose particle size has been reduced to be primarily 50 to 100 mesh in size such as Magnafloc 156F from Ciba Specialties
iv) from 0 to 5% of a powdered silicone defoamer such as AU-319 from Adjuvants Unlimited Inc. or other suitable silicone defoamers on a water soluble powdered base
v) from 0 to 30% of a nonionic powdered surfactant prepared preferably as a clathrate(urea complex)
vi) from 0 to 50% of specialty sequestering agents/sequestered metals such as ethylene diamine tetra acetic acid(or its salts), citric acid(or its
Brigance Mickey
McManic Greg
Adjuvants Unlimited Inc.
Sayala Chhaya D.
Smith , Gambrell & Russell, LLP
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