Field of the Invention
The present invention is broadly concerned with a new class of substantially water soluble, biodegradable polyanionic polymers and syntheses thereof finding particular utility in agricultural uses, e.g., directly applied to soil, or in combination with fertilizers to increase nutrient uptake; as seed coatings and pesticide adjuvants; to reduce atmospheric ammonia derived from animal manures; as animal feed and water amendments; and to inhibit nitrification, urease hydrolysis, and phosphate fixation in soils. More particularly, the invention is concerned with novel polymers that are at least tetrapolymers and preferably contain specific types of carboxylic and sulfonate repeat units, as well as methods of synthesizing dicarboxylate/sulfonate polymers including the novel polymers hereof. Other uses of the polyanionic polymers are also disclosed, alone or in combination with other polyanionic (e.g., dicarboxylic) polymers and/or other functional ingredients.
Description of the Prior Art
For a number of years, Specialty Fertilizer Products, LLC of Leawood, Kans., has commercialized a series of aqueous dispersions of maleic-itaconic polymers in partial salt form. These products include AVAIL® for use with granular and liquid fertilizers (respectively the partial sodium and ammonium salts), and NUTRISPHERE-N® for use with granular and liquid fertilizers (the partial calcium salt). For example, such products may be sprayed or otherwise applied to the surface of solid fertilizers, such as urea, ammonium salts, monoammonium phosphate (MAP), diammonium phosphate (DAP), potash, and gypsum, or mixed with liquid fertilizers, such as UAN and ammonium polyphosphate.
These prior products have been shown to have a number of outstanding agricultural properties, including the ability to enhance the uptake of fertilizer nutrients (e.g., phosphates, nitrogen, potassium, and micronutrients), to act as adjuvants for pesticides such as glyphosate herbicides, and, when supplemented with an organic drying agent, to very quickly dry when applied to solid fertilizers, thereby facilitating production of final coated solid fertilizer products. Moreover, the preferred polymers have been shown to have enhanced activity when fertilizer formulations containing different types of polymer partial salts are employed (U.S. Patent Publication No. 2009-0217723). This technology is also described in U.S. Pat. Nos. 6,515,090, 7,655,597, 7,736,412, and 8,043,995, and related patents.
Notwithstanding the success of the prior maleic-itaconic polymers, agriculturally useful polymers having even greater activities would be desirable.