Melt agglomeration

Nucleation is the initial phase of agglomeration in which nuclei or small agglomerates of loose and porous structure are formed after the primary particles are wetted by a binding liquid droplet. The primary particles are bound by liquid bridges in the 

In nucleation by distribution method, a molten binding liquid is distributed onto the surfaces of fine solid particles. The nuclei are formed by the collision between the wetted particles. The formed nuclei have a loose structure with entrapped air unlike those produced by the immersion method. Generally, small binder droplet size, low binder viscosity, and high shearing forces are favorable conditions for nucleation by the distribution method. 

The nucleation phase is characterized by the disappearance of fines (35), as a consequence of coalescence between the wetted primary particles or the primary particles with the formed nuclei. The resultant nuclei would undergo consolidation under the impact of the externally applied mechanical forces and acquire sufficient 

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The melt processes require at least a meltable material in the manufacture of the solid dosage form. This article intends to address the influence of meltable materials on the processes of melt pelletization, melt granulation, and tumbling melt granulation. Approaches to meet the processing attributes of the meltable materials for these melt agglomeration processes, via spray congealing, are discussed. 

By the size enlargement processes, melt agglomeration may be employed to produce multiple-unit solid dosage form. The melt agglomerates are called... 

Two modes of melt agglomeration based on the elementary mechanisms have been proposed—distribution and immersion. In agglomeration by the distribution mode, a distribution of molten binding liquid on the surfaces of primary particles will occur, and agglomerates are formed via coalescence between the wetted nuclei (Fig. 3). In agglomeration by the immersion mode, nuclei are formed by immersion of the primary particles onto the surface of a droplet of molten binding liquid (Fig. 3). The distribution of molten binding liquid to surfaces of... 

Table 1 Types of meltable binders in the melt agglomeration process...

Eliasen, H. Kristensen, H.G. Schaefer, T. Growth mechanisms in melt agglomeration with a low viscosity binder. Int. J. Pharm. 1999,186, 149-159. 

Melt granulation is a process by which granules are obtained through the addition of either a molten binder or a solid binder that melts during the process. This process is also called melt agglomeration and thermoplastic granulation. ... 

Chemical/physical reactions during agglomeration. In a holt-melt agglomeration process, the hot-melt binder typically is of low viscosity initially but immediately starts to harden on contact with the cooler powder. Hence, the deformability of the agglomerating mass is constantly changing. 

Seo A, Holm P, Schaefer T. Effects of droplet size and type of binder on the agglomerate growth mechanisms by melt agglomeration in a fluidized bed. Eur J Pharm Sci 2002 16 95-105. 

Schaefer T. Melt Agglomeration with Polyethylene Glycols in High Shear Mixers. Ph.D. thesis. The Royal Danish School of Pharmacy, Copenhagen, 1996. 

The growth processes of melt agglomerates are highly sensitive to formulation, processing, and equipment variables. Uncontrollable melt agglomeration is... 

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