Extended-release urea-based granular fertilizer
View Patent ↗An improved granular-type urea fertilizer having an extended or slow release nitrogen component in which a non-thermosetting urea-formaldehyde resin concentrate is used to provide the granular fertilizer with an extended-release nitrogen component.
1. A granular-type urea fertilizer comprising a mixture of from 50% to 95% by weight urea and 50% to 5% by weight of non-thermosetting urea-formaldehyde resin solids based on the combined weight of the urea and the non-thermosetting urea-formaldehyde resin solids.
2. The granular-type urea fertilizer of claim 1 wherein the urea-formaldehyde resin solids are made by reacting formaldehyde (F), urea (U) and optionally ammonia (A) and optionally a primary amine (A) in the absence of acid condensation at a mole ratio of urea to formaldehyde to ammonia and primary amine (F:U:A) in the range of 0.5-4.0:1.0:0.0-1.0.
3. The granular-type urea fertilizer of claim 2 wherein the urea-formaldehyde resin solids is made by reacting formaldehyde, urea and optionally ammonia and optionally a primary amine in the absence of acid condensation.
4. The granular-type urea fertilizer of claim 2 wherein the urea-formaldehyde resin solids contains more than 20% by weight triazone.
5. A process for making a granular-type urea fertilizer comprising mixing urea with an non-thermosetting urea-formaldehyde resin concentrate to provide a fluid mixture containing from 50% to 95% by weight urea and from 50% to 5% by weight of urea-formaldehyde resin solids based on the combined weight of the urea and the non-thermosetting urea-formaldehyde resin solids, the urea being in a form selected from a urea melt and a concentrated urea solution; and then solidifying the fluid mixture to produce the granular-type fertilizer comprising a mixture of urea and non-thermosetting urea-formaldehyde resin solids.
6. The process of claim 5 wherein the non-thermosetting urea-formaldehyde resin concentrate is made by reacting formaldehyde (F), urea (U) and optionally ammonia (A) and optionally a primary amine (A) in the absence of acid condensation at a mole ratio of urea to formaldehyde to ammonia and primary amine (F:U:A) in the range of 0.5-4.0:1.0:0.0-1.0.