Improved Dispersion and Processing of Chromatic Pigments in Plastics

摘要

1. Pigments, being crystalline in nature, must be dispersed fully to achieve their value in application. The consequences of poor dispersion are many but include loss in value beyond simply the proportion of undispersed material. 2. Some organic pigments are compactable meaning that inappropriate compression during processing increases particle size rather than reducing it. There has been developed a test for measuring compaction and the values reported can guide the processor in selection of the best type of pigment processes. 3. It is beneficial to understand compaction so that processing conditions can be optimized. Some effects of compaction are counter-intuitive, for example faster extrusion throughput and lower shear can result in higher strength for some pigments. Dispersion operations both aggregate and de-agglomerate pigments in a dynamic balance of forces. 4. Recently, oversized particle controlled pigments have been developed that have narrower particle size distributions. These have value advantages for the processor; processes can be run more efficiently and higher quality dispersions will lead to opportunities in dispersion-critical applications.