Managing Dual Use Additives Information Flow in Plastic Packaging Declarations
Dual use additive management demands specific identity flow from resin compounders to food packers to satisfy direct food additive maximum limits.
Fatty Acid Amides
Meaning
Organic surface modifiers represent a distinct class of additives used to adjust the frictional properties of polymers. Chemical structures known as fatty acid amides migrate to the surface of molded or extruded plastics to form a thin, lubricating layer. This layer reduces the coefficient of friction between the plastic and metal processing equipment or other plastic surfaces.
These compounds are commonly added to polyolefins during compounding or film extrusion.
Slip Performance
Migration rate determines how quickly the additive establishes a slippery surface on the plastic. After extrusion, fatty acid amides migrate from the bulk polymer to the surface due to their limited solubility in the polymer matrix. Erucamide and oleamide are two common examples that exhibit different migration speeds and thermal stabilities.
The resulting drop in friction prevents film layers from sticking together and facilitates automated packaging operations.
Melt Processing
Incorporating these amides affects the behavior of the polymer melt inside the extruder barrel. They act as internal lubricants, reducing melt viscosity and torque during processing. This lubricating effect can lower the temperature required to process the resin, which protects the polymer from thermal degradation.
However, excessive amounts can cause screw slippage, reducing throughput and leading to erratic pressure profiles.
Secondary Effect
Downstream operations can be disrupted if the concentration of the additive is not controlled. When fatty acid amides accumulate excessively on the part surface, they interfere with printing inks, adhesives, and metallization layers. This blooming effect can also cause visual defects like haze or a greasy feel on the finished part.
Molders must balance the slip requirements against the needs of subsequent assembly or decoration steps to avoid surface contamination. Adjusting the additive concentration in the masterbatch is the primary method used to control this behavior.
Analytical Screening Methods for Unintentional Additive Degradation Products in Finished Rigid Packaging
Analytical screening of additive degradation products in rigid packaging demands hyphenated mass spectrometry matched against finished container migration testing.