BACKGROUND OF THE INVENTION

A. Field of the Invention

The invention generally concerns urea-aldehyde condensation compositions, processes for preparing the same, and the use of the condensation compositions as fertilizers. The condensation compositions can be free of hot water insoluble nitrogen (HWIN).

B. Description of Related Art

Urea-aldehyde condensates and polymers thereof are typically used in products ranging from slow-release fertilizers and feed for cattle to binders, resins, plastics, and insulating materials (Jahns et al. Journal of Polymers and the Environment (2003) 11:155; U.S. Pat. No. 9,340,495). Short chain urea-aldehyde condensates and polymers are especially valuable for use in fertilizers because of their water soluble nitrogen content.

Conventionally, urea-aldehyde condensates are generated by the reaction of urea with formaldehyde and optionally a higher aldehyde (C2 and greater aldehyde) under acidic conditions and temperatures of greater than 50° C. to form urea-aldehyde condensate polymers (see U.S. Pat. Nos. 3,459,528; 4,298,512). The reaction is typically stopped by increasing the pH to approximately 7 to 8. When a higher aldehyde is used, molar ratios of formaldehyde to higher aldehyde are typically 9:1 to 1:3.

However, synthesis of short chain urea condensed products can be challenging due to the rate of polymerization. In particular, the ratio of urea to aldehyde(s) or amides, reaction temperatures, and the order of addition of the reactants can play a major role in the degree of polymerization, which can detrimentally affect the water soluble content of the resulting reaction products. As an example, U.S. Pat. Nos. 3,441,539 and 4,298,512 each disclose the use of various reaction conditions to form urea condensates. These condensates included HWIN or insoluble nitrogen when isobutyraldehyde, isobutylidenediurea (IBDU), or acetaldehyde were used in the condensation reaction.

The presence of HWIN in short chain urea-aldehyde condensate fertilizer products can result in a product that does not provide a consistent and steady release of nitrogen to plants throughout a given growing season. For example, HWIN can be undesirable in quick release fertilizers. Further, the slow nature of nitrogen release from HWIN can result in irregular fertilization of plants and negatively affect plant growth and production.

SUMMARY OF THE INVENTION

A discovery has been made that provides a solution to the aforementioned problems associated with producing urea-aldehyde condensate products. In particular, the solution is premised on reacting urea with various C1-C4 aldehydes under particular reaction conditions to form urea-aldehyde condensates that can be free of HWIN. In preferred instances, the reactants can include urea, a first C1-C4 aldehyde (e.g., formaldehyde, butyraldehyde, isobutyraldehyde, or crotonaldehyde), and at least a second C1-C4 aldehyde that can be the same or different than the first C1-C4 aldehyde. The reaction can be run at a temperature of 25° C. to up to 100° C. and the temperature can be the same or different in each step of the reaction. Additionally, the process can begin with a base-catalyzed reaction and then be pushed to an acid-catalyzed reaction (e.g., by adjusting the pH of the reaction medium from basic to acidic). Notably, the C1-C4 aldehydes can be introduced at different periods of time (e.g., a first C1-C4 aldehyde can be introduced during the base-catalyzed reaction and additional C1-C4 aldehydes can also be introduced during the base-catalyzed reaction and/or during the acid-catalyzed reaction). Without wishing to be bound by theory, it is believed that apart from reaction conditions such as temperature and time, the order of addition of reactants allows for more efficient control of the degree of polymerization during the reaction and can result in urea-aldehyde condensates free of HWIN. Also, the inclusion of a second C1-C4 aldehyde during the acidification step is believed to provide the ability to control the amount of cold water soluble nitrogen (CWSN) and hot water soluble nitrogen (HWSN) present in the resulting product. Still further, the process of the present invention can be performed in a single reaction chamber or vessel (i.e., a “one-pot” reaction scheme) by adjusting the pH of the reaction mixture from basic to acidic and then to neutral to stop the reaction, which provides for an efficient and scalable production process that can meet the ever growing needs of the fertilizer industry.

In one aspect of the present invention, a method for producing a urea condensation composition is disclosed. The method can include (a) reacting a solution containing urea, formaldehyde, and at least one C2-C4 aldehyde under basic conditions to form a first composition, and (b) acidifying the first composition to form a urea condensation composition containing at least one urea oligomer. Alternatively, the method can include (a) reacting a solution containing urea and formaldehyde under basic conditions to form a first composition, and (b) reacting the first composition and at least one C2-C4 aldehyde under acidic conditions to form a urea condensation composition containing at least one urea oligomer. Still further, the method can include (a) reacting a solution containing urea and at least one first C1-C4 aldehyde or a derivative thereof under basic conditions to form a first composition, and (b) reacting the first composition and at least one second C1-C4 aldehyde or a derivative thereof under acidic conditions to form a urea condensation composition containing at least one urea oligomer. In preferred instances, the first and second C1-C4 aldehydes are different. In each alternative, the resulting urea condensation composition can be free of HWIN.

In some instances, step (a) includes heat-treating the solution at a temperature of 40° C. to up to or less than 100° C., 50° C. to up to or less than 70° C., 60° C., 50° C., or any range therein. The solution in step (a) can react for any amount of time. In some instances, the reaction is reacted for at least 30 minutes, for no more than 90 minutes, and/or for 60 minutes, or any time therein. In some instances, the solution in step (a) has a pH of about 8 to about 10.

The amount of the urea, formaldehyde, at least one C2-C4 aldehyde, and/or at least one C1-C4 aldehyde in the reaction step (a) can be any amount sufficient to carry out the base-catalyzed reaction. In some instances, the mol. % ratio of urea to the combined formaldehyde and the at least one C2-C4 aldehyde in step (a) is 2:1 or greater. In some instances, the mol. % ratio of formaldehyde to the at least one C2-C4 aldehyde is 9:1 to 1:3 in step (a). In some instances, the mol. % ratio of urea to the combined formaldehyde and the at least one C2-C4 aldehyde is 2:1 or greater, and the mol. % ratio of formaldehyde to the at least one C2-C4 aldehyde is 9:1 to 1:3 in step (a).

In some instances, the pH of the first composition in step (b) is decreased to about 2 to about 5. In some instances, step (b) polymerizes the urea in the presence of the one or more aldehyde. In some instances, the acidifying step (b) is performed at a temperature of 25° C. to up to or less than 60° C., and/or at 45° C., or any temperature therein. In some instances, the acidified step (b) can further include allowing the acidified composition to polymerize for any amount of time. In some instances, the acidified composition is allowed to polymerize for at least 30 minutes, for no more than 90 minutes, and/or for 60 minutes, or any time therein. In further instances, the pH of the reaction in step (b) can subsequently be increased to neutral (about 7 to about 8, preferably about 7 to 7.5) or a basic pH to stop the polymerization reaction.

The C1-C4 aldehydes used in the processes of the present invention can be any C1-C4 aldehyde, derivative thereof, or combination thereof. In some instances, the C1-C4 aldehydes can be formaldehyde, butyraldehyde, isobutyraldehyde, crotonaldehyde, or any combination thereof. The formaldehyde can be in a variety of forms such as its aldehyde form (CH2O), its hydrated form (methanediol), and its paraformaldehyde form. In some particular instances, the formaldehyde can be urea formaldehyde concentrate-85, or formalin containing 37-65% formaldehyde.

The method of the present invention can produce urea oligomers. In some instances, the urea is condensed with formaldehyde, a C2-C4 aldehyde, a first C1-C4 aldehyde, a second C2-C4 aldehyde or any combination thereof. In some instances, the method produces more than one urea oligomer. In some instances, the method consumes 85 wt. % or more of the urea (product contains 15 wt. % or less urea). In some instances, the method produces at least one C1-C4/urea oligomer and consumes at least 85 wt. % of the urea. In some instances, the method produces at least one methylene urea oligomer and at least one isobutylidenediurea derivative. In some instances, the at least one C1-C4/urea oligomer includes isobutylidenediurea, mono (ureidomethylene) isobutylenediurea, bis(ureidomethylene) isobutylenediurea, and at least two, three, or all four methylene urea oligomers selected from the group consisting of methylene diurea, dimethylene triurea, trimethylene tetraurea, and tetramethylene pentaurea.

The methods of the present invention can be used to produce a urea condensation composition wherein 100% of the nitrogen content is water soluble. In some instances, the nitrogen content is at least 32%, 32% to 42%, or 35 to 38% by weight of the composition. In some instances, the water-soluble nitrogen content contains 50%, 50% or more, 60% or more, 75% or more, 80% or more, or 82% or more of cold water-soluble nitrogen content.

In some aspects of the present invention, there is disclosed a method for producing a urea condensation composition by (a) heat-treating a basic aqueous solution having a pH of about 8 to about 10 to a temperature of 40° C. to less than 100° C. for 30 minutes to 90 minutes, the basic aqueous solution containing urea, formaldehyde, and isobutyraldehyde, wherein the mol. % ratio of formaldehyde to isobutyraldehyde is 9:1 to 1:3 and the mol. % ratio of urea to the combined formaldehyde and isobutyraldehyde is 2:1 or greater, and (b) acidifying the basic aqueous solution from step (a) to have a pH of about 2 to about 5 to polymerize the urea in the presence of the formaldehyde and isobutyraldehyde at 25° C. to less than 60° C. for 30 minutes to 90 minutes, preferably at 45° C. for 60 minutes, to form a urea condensation composition containing at least one methylene urea oligomer and at least one isobutylidenediurea derivative.

Also disclosed in the context of the present invention is a urea-condensation composition containing at least one C1-C4/urea oligomer and includes less than 15 wt. % urea and has a nitrogen content that is 100% water-soluble (i.e., all of the nitrogen in the composition is water soluble). In some instances, the water-soluble nitrogen content is 50%, 50% or more, 60% or more, 75% or more, 80% or more, or 82% or more of cold water-soluble nitrogen. In some instances, the at least one C1-C4/urea oligomer includes at least one isobutylidenediurea derivative and at least one methylene urea oligomer. In some instances, the at least one C1-C4/urea oligomer includes isobutylidenediurea, mono (ureidomethylene) isobutylenediurea, bis(ureidomethylene) isobutylenediurea, and at least two, three, or all four methylene urea oligomers selected from the group consisting of methylene diurea, dimethylene triurea, trimethylene tetraurea, and tetramethylene pentaurea.

The urea condensation composition or one or more chemicals therein can be formulated into any composition, such as, but not limited to, fertilizers, edible products, binders, resins, plastics, and insulating materials. In some instances, the composition is formulated into a fertilizer. In some instances, the composition is formulated into a slow-release fertilizer. In some instances, the composition is formulated into a specialty fertilizer. The processes disclosed herein can further include the step of mixing the condensate or one or more chemicals therein with another fertilizer, secondary nutrient, trace element, plant protection agent, filler, and/or with other fertilizer ingredients to form a mixed fertilizer.

Also disclosed are the following Embodiments 1 to 20 of the present invention. Embodiment 1 is a method for producing a urea condensation composition comprising: (a) reacting a solution comprising urea, formaldehyde, and at least one C2-C4 aldehyde under basic conditions to form a first composition; and (b) acidifying the first composition to form a urea condensation composition comprising at least one urea oligomer. Embodiment 2 is the method of Embodiment 1, wherein step (a) and (b) further comprises heat-treating the solution at a temperature of 25° C. to less than 100° C. Embodiment 3 is the method of any of Embodiments 1 to 2, wherein the at least one C2-C4 aldehyde comprises butyraldehyde, isobutyraldehyde, crotonaldehyde, or any combination thereof. Embodiment 4 is the method of any of Embodiments 1 to 3, wherein the urea condensation composition comprises a nitrogen content that is 100% water soluble. Embodiment 5 is the method of any of Embodiments 1 to 4, wherein the urea condensation composition comprises a nitrogen content that is at least 32%, 32% to 42%, or 35 to 38% by weight of the urea condensation composition. Embodiment 6 is the method of any of Embodiments 1 to 5, wherein the urea condensation composition comprises a water soluble nitrogen content comprising 60% or more, 75% or more, 80% or more, or 82% or more of cold water soluble nitrogen content. Embodiment 7 is the method of any one of Embodiments 1 to 6, wherein steps (a) and (b) comprise: (a) heating-treating the solution at a pH of about 8 to about 10 at a temperature of 40° C. to less than 100° C. for 30 minutes to 90 minutes, the solution comprising water, urea, formaldehyde, and isobutyraldehyde, wherein the mol. % ratio of formaldehyde to isobutyraldehyde is 9:1 to 1:3 and the mol. % ratio of urea to the combined formaldehyde and isobutyraldehyde is 2 or greater: 1; (b) acidifying the first composition from step (a) to have a pH of about 2 to about 5 to polymerize the urea in the presence of the formaldehyde and isobutyraldehyde at 25° C. to less than 60° C. for 30 minutes to 90 minutes, preferably at 45° C. for 60 minutes, to form a urea condensation composition comprising at least one methylene urea oligomer and at least one isobutylidenediurea derivative. Embodiment 8 is the method of any of Embodiments 1 to 7, further comprising: (c) formulating the urea condensation composition of step (b) in a fertilizer composition. Embodiment 9 is a urea condensation composition comprising: at least one C1-C4/urea oligomer; and less than 15 wt. % urea, wherein the urea condensation composition has a nitrogen content comprising 100% water soluble nitrogen content. Embodiment 10 is the urea condensation composition of Embodiment 9, wherein the water soluble nitrogen content comprises 75% or more, 80% or more, or 82% or more of cold water soluble nitrogen content. Embodiment 11 is the urea condensation composition of any of Embodiments 9 to 10, wherein the at least one C1-C4/urea oligomer comprises: at least two, three, or all four methylene urea oligomers selected from the group consisting of methylene diurea, dimethylene triurea, trimethylene tetraurea, and tetramethylene pentaurea; isobutylidenediurea; mono (ureidomethylene) isobutylenediurea; and bis(ureidomethylene) isobutylenediurea. Embodiment 12 is a method for producing a urea condensation composition comprising: (a) reacting a solution comprising urea and at least one first C1-C4 aldehyde or a derivative thereof under basic conditions to form a first composition; and (b) reacting the first composition and at least one second C1-C4 aldehyde or a derivative thereof under acidic conditions to form a urea condensation composition comprising at least one urea oligomer, wherein the at least one first C1-C4 aldehyde is different from the least one second C1-C4 aldehyde. Embodiment 13 is the method of Embodiment 12, wherein the at least one first C1-C4 aldehyde or at least one second C1-C4 aldehyde comprises formaldehyde, butyraldehyde, isobutyraldehyde, crotonaldehyde, or any combination thereof. Embodiment 14 is the method of Embodiment 12, wherein the first aldehyde in step (a) is formaldehyde and the second aldehyde in step (b) is a C2-C4 aldehyde. Embodiment 15 is the method of Embodiment 14, wherein the second C2-C4 aldehyde in step (b) is butyraldehyde, isobutyraldehyde, crotonaldehyde, or any combination thereof. Embodiment 16 is the method of any of Embodiments 12 to 15, wherein the urea condensation composition comprises a nitrogen content that is 100% water soluble. Embodiment 17 is the method of any of Embodiments 12 to 16, wherein the urea condensation composition comprises a nitrogen content that is at least 32%, 32% to 42%, or 34 to 38% by weight of the urea condensation composition. Embodiment 18 is the method of any of Embodiments 12 to 17, wherein the urea condensation composition comprises a water soluble nitrogen content comprising 60% or more, 75% or more, 80% or more, or 82% or more of cold water soluble nitrogen content. Embodiment 19 is the method of any of Embodiments 12 to 18, further comprising: (c) formulating the urea condensation composition of step (b) in a fertilizer composition.

The following includes definitions of various terms and phrases used throughout this specification.

“Free of hot water insoluble nitrogen (HWIN)” or “HWIN free” includes a composition that includes 0.5 wt. % or less of HWIN, preferably 0 wt. % HWIN.

A “C1-C4 aldehyde” and/or “C2-C4 aldehyde” can be a straight or branched aldehyde, saturated or unsaturated aldehyde, a substituted aldehyde, etc. having 1 to 4 carbon atoms or 2 to 4 carbon atoms, respectively. Non-limiting examples include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, and crotonaldehyde.

“Nitrogen content” of a composition is the nitrogen contained in the composition. It can include free nitrogen in the composition and nitrogen present in a given compound (e.g., a C1-C4/urea oligomer of the present invention has nitrogen present in its chemical structure) that is present in the composition. The amount of nitrogen content in a composition can be expressed in a percentage of weight/weight (wt./wt.) of nitrogen in a composition. The nitrogen of the composition can be water soluble and/or hot-water insoluble.

“Water soluble-nitrogen” can include any nitrogen content that is soluble in water at or below 100° C. Water soluble-nitrogen content can include cold water-soluble nitrogen content (CWSN) and hot water-soluble nitrogen content (HWSN), but does not include hot water-insoluble nitrogen content (HWIN). “Cold water-soluble nitrogen” is any nitrogen containing compound that is soluble in water below and at 25° C. “Hot water-soluble nitrogen” is any nitrogen containing compound that is soluble in water below and at 100° C. but is not soluble in water below 26° C. “Hot water-insoluble nitrogen” is any nitrogen content that is not soluble in water below 101° C.

The term “short chain” methyleneureas can include methyleneureas containing one to five urea units.

The terms “about”, “approximately”, and “substantially” are defined as being close to, as understood by one of ordinary skill in the art. In one non-limiting instance, the terms are defined to be within 10%, preferably, within 5%, more preferably, within 1%, and most preferably, within 0.5%.

The terms “wt. %,” “vol. %,” or “mol. %” refers to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume, or the total moles of material that includes the component. In a non-limiting example, 10 grams of a component in 100 grams of the material that includes the component is 10 wt. % of component.

The use of the words “a” or “an” when used in conjunction with any of the terms “comprising,” “including,” “containing,” or “having” in the claims or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.”

The words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”), or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

The process of the present invention can “comprise,” “consist essentially of,” or “consist of” particular ingredients, components, compositions, etc., disclosed throughout the specification. With respect to the transitional phase “consisting essentially of” in one non-limiting aspect, a basic and novel characteristic of the process of the present invention is the ability to produce a urea condensation composition from urea, a first C1 to C4 aldehyde, and a second C1 to C4 aldehyde. Preferably, the composition is free of HWIN.

Other objects, features and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes, combinations, and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

