Meaning
Polymer base acts as the dispersion medium for pigments, additives, or fillers in a concentrated plastic compound. The masterbatch carrier resin must be compatible with both the high concentration of additives and the target moulding resin. It melt blends during the final injection or extrusion process, ensuring that colorants or functional chemicals are uniformly distributed throughout the molded part.
Polymer Compatibility
Selecting the correct base polymer avoids material failure and mechanical defects in the molded part. Choosing a masterbatch carrier resin that matches or is highly compatible with the host polymer ensures homogeneous blending. For example, a polyethylene carrier works well in polyethylene compounds but can cause delamination if used in polystyrene.
This choice governs the structural integrity of the final manufactured product.
Flow Performance
Melt flow properties of the carrier resin are critical for dispersing additives. High molecular weight polymers often struggle to wet out pigments, so a masterbatch carrier resin is usually selected to have a higher melt flow index than the target resin. This high flow allows the masterbatch to melt quickly and mix thoroughly at lower shear rates.
It reduces processing time and energy costs in the factory while preventing the agglomeration of pigments that can lead to visible streaks in the final molded product.
Processing Effect
Incorrect selection can lead to surface blemishes or weakened part weld lines. If the masterbatch carrier resin has a much lower melting point than the base resin, it can degrade during high temperature injection molding. This degradation produces gas bubbles and silver streaks on the part surface.
Processors must ensure that the carrier resin does not compromise the heat stability of the final compound.
