Meaning
Chemical salt additives functioning as internal lubricants and acid scavengers reduce friction during thermal processing of synthetic polymers. Calcium stearate acts in polyvinyl chloride and polyolefin formulations to neutralize corrosive catalyst residues and lower melt viscosity. Polymer compounders inject this white powder to prevent melt fracture and torque spikes during high-speed extrusion.
Over-dosing causes plate-out on mould cavity surfaces and reduces printability of finished packaging films.
Additive Functionality
Molecular interactions during polymer extrusion rely on precise lubricant dosing to maintain stable torque levels. Integrating calcium stearate into polyolefin blends neutralizes residual acidic catalysts, protecting metal extruder screws from pitting. Processing engineers adjust lubricant levels to balance internal shear reduction against external mould release performance.
Excessive loading leads to surface bloom and degraded weld line strength.
Thermal Stability
Polymer melting efficiency improves when processing aids prevent local overheating in high-shear extrusion dies. Adding calcium stearate reduces melt pressure during thin-wall injection moulding, allowing faster cycle times without increasing melt temperature. Compounding plants monitor moisture content in the powder feed to prevent steam void defects in extruded sheet products.
Consistent particle size distribution ensures uniform dispersion throughout the polymer matrix.
Datasheet Specifications
Material datasheets for raw additive purity set maximum levels for moisture and free fatty acid impurities. Uncontrolled variance in calcium stearate concentration causes unstable die swell and fluctuating melt flow index readings during continuous production. QC laboratories verify lot consistency using titration and ash content testing.
Substandard lubricant lots result in expensive downtime for tool cleaning.
