Abstract
In order to design and control a release pattern of active component, the release characteristics were investigated for the particles coated with multiple layers of fine soluble and permeable particles dispersed in the impermeable wax. The effect of the operational conditions was examined on parameters of the release profile by multivariate analysis. The simplified correlations were obtained for the maximum release rate by the slope and the lag time of the release curve as a function of the volume fraction of permeable particles and the thickness of the permeable- and soluble-particle layers. As a result, it was confirmed that the desired release rate could be obtained in the first place by adjusting the volume fraction and thickness of the permeable-particle layer. Then the required lag time might be attained by changing the thickness of the soluble layer. Finally, the possibility to design the controlled-release particles with the prescribed sigmoidal release pattern was successfully illustrated by the calculation example.
