Talc is used as a filler inpolypropylene (PP), high density polyethylene (HDPE), low density polyethylene (LDPE), polyvinyl chloride (PVC), etc.
In this application, its properties like high specific heat (ability to take heat without much increase in temperature), high electrical resistance, good mechanical strength, resistance to ultraviolet light, greasiness, platy structure, chemical inertness and high oil absorption are made use of.
These improved plastic materials find use in automobile dashboards and bumpers requiring mechanical strength, computer bodies requiring high specific heat and electrical resistance and garden chairs requiring high specific heat and resistance to ultraviolet light. In all these applications, smoothness and greasiness of talc are carried to the product and platy structure gives smooth finish.
High oil absorption ensures excellent mixing of talc with the oleo-resinous materials and inertness prevents chemical reaction between them.
For ensuring colour neutrality, talc should be strongly white with a degree of whiteness 92-98% (cf., value for fresh titanium dioxide which is the whitest substance is 98-100%) and the content of Fe2O3 should be not more than 0.5 percent. For uniform dispersion within the matrix, industries specify ultra-fine particle size and for high-quality sensitive products the size is as small as one micron.