Polyurethane encapsulated fertilizer having improved slow-release properties
US6364925B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 10, 1999 |
| Grant date | Apr 2, 2002 |
| Priority date | — |
| Expiry date | Dec 10, 2019 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G18/6696
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
The present invention relates to polyurethane encapsulated fertilizer particles which exhibit slow-release properties and to a process for their production. The process comprises applying an isocyanate-reactive component to fertilizer particles, to form fertilizer particles coated with an isocyanate-reactive component, applying a polyisocyanate component onto the coated fertilizer particles to form polyurethane encapsulated fertilizer particles, and, optionally, repeating these steps as many times as necessary to form the polyurethane encapsulated fertilizer particles that contain about 2 to 20% by weight of polyurethane, based on the total weight of the encapsulated fertilizer particles. Suitable isocyanate-reactive components include polyesterether polyols that comprise either a blend of or the reaction product of (i) castor oil having an OH number of about 160 to about 170, a viscosity of about 500 to about 900 mPa.s at 25° C., and a water content of less than 0.5% by weight; and (ii) a polyether polyol having an OH number of from 28 to 700, a functionality of from 3 to 8, and a molecular weight of about 240 to about 6,000, and a viscosity of from about 50 to 35,000 mPa.s at…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.