Residual Solvent Capacity
Solvent entrapment within laminated flexible packaging structures describes the quantity of ethyl acetate remaining in a film after the adhesive curing process. The chemical compound ethyl acetate acts as a carrier for many printing inks and laminating adhesives used in high speed converting lines. Manufacturers quantify this value to ensure compliance with strict migration limits set for food contact materials.
Odour transfer and potential product tainting occur when levels exceed threshold limits during the shelf life of a finished package.
Measurement Protocol
Gas chromatography head space analysis identifies the concentration of the trapped solvent through a heat induced evaporation cycle. Operators place a specific sample weight into a sealed vial to allow the internal atmosphere to reach equilibrium at a set temperature. The machine then draws a gas aliquot for separation and detection against a known calibration curve.
This method provides the parts per million count required for quality control documentation.
Converting Impact
High retention values result from insufficient tunnel temperatures or inadequate airflow during the lamination phase of production. Operators adjust the drying line settings when detected concentrations rise above the safe operating tolerance for specific substrates. Thin gauge films and low grammage coatings require longer dwell times to prevent solvent blocking within the reel.
Proper moisture and temperature balance during storage limits the migration of these residues into the stored product contents.
