In the present invention, a process for preparing a zinc stearate dispersion is provided. The process is less strenuous on equipment than a size-reducing homogenization method and provides a dispersion with a particle size distribution comparable to that of a stearate powder. The in-situ process also saves time and money and is especially suitable for applications requiring a high degree of toner particle coverage, such as rubber slab dipping processing.
The process is carried out by bringing a metal stearate solution and a lubricant together in one step. The lubricant is first introduced into the mixture and the zinc salt added afterward. This process is particularly useful where it is desired to achieve a lubrication level that exceeds the level achievable by homogenization using size-reducing technology.
For example, the dispersion prepared by this method can be used to coat a 3 to 4 microns size non-pigmented resin particle in a rubber slab dipping application. The aqueous dispersion is capable of achieving a GSDv value of 0.15 to 0.2 (selective coating). This level of coverage is far superior to the results achieved by the size-reducing homogenization method.
The aqueous dispersion produced by the process of the present invention is stable and will not separate under ambient temperatures without adequate agitation. However, if separation does occur, the dispersion can be re-dispersed by stirring. In addition, the aqueous dispersion is free of odors and is readily biodegradable.