Experimental modeling of polymer latex spray coating for producing controlled-release urea

Spray coating of polymer latex onto fertilizer particles in a fluidized bed for producing controlled-release urea is an environment friendly technology as it does not need any toxic organic solvent. Since the spray coating process in a fluidized bed occurs in the presence of particle collisions, the coating of the particles is random, intermittent and multiple, thus making it difficult to investigate the film formation process. In this paper, an experimental model apparatus was designed and used to investigate the effects of the key factors in the spray coating process. This apparatus reasonably simplified the complex process to avoid particle collisions and randomness in the coating. The intermittent coating in the fluidized bed was modeled by periodic coating and dewatering in the experimental apparatus. A large area film was obtained, and the film permeability was measured. The effects of atomizing gas flow rate, spray rate of latex, solid content of latex and gas temperature on film structure and film permeability were investigated. It was found that water transfer played a dominant role in the spray coating process.

An experimental model apparatus was designed and used to simulate random, intermittent, multiple coating-dewatering in fluidized bed for studying spray coating process in production of controlled-release urea. It was found that water transfer played a dominant role in the spray coating process.Figure optionsDownload as PowerPoint slide