Study on filler dispersion

Abstract

Processing aids lower the surface friction of polyolefin (PO) films, allowing the film to be rapidly extruded and then shipped or stored in rolls. Or they allow resin to be converted easily in blown-film processes or in thermoforming processes. Other extruded POs likewise benefit from the friction-reducing properties of slip agents, antiblocking agents, and other processing aids, whether they are added to resin by the resin producer or by the converters themselves. This chapter reviews processing aids in the context of extrusion, with particular attention on cast and blown films. This chapter discusses the particular needs of extrusion processes and how these needs are addressed by slip agents, antiblocking agents, and aids that prevent melt fracture. Some of the unique extrusion situations that require special attention in the choice of processing aid are also elaborated. Various processing aids serve the needs of cast- and blown-film converters and other extrusion operations including high line speeds, more efficient conversion operations downstream, printability and adhesion, process cleanliness, process flexibility, and low scrap. Slip agents lower the sliding coefficient of friction (CoF) between a film and processing equipment or other surfaces (including the film itself). Similar to and sometimes overlapping with the functions of slip agents, antiblocking agents prevent layers of smooth PO film forced into close contact from sticking to one another. Antiblocks include both organic and inorganic additives. “Clarity antiblocks” or “high-clarity slip antiblocks” are recent formulations that combine a mineral antiblocking ingredient with a slip and/or clarifying agent.