Solvent Retention
Chemical residues on printed packaging films can affect the quality of sensitive food and pharmaceutical products. The presence of ethyl acetate residual occurs when solvent-based inks or adhesives fail to dry completely during the drying stage of the converting process. Flexographic and gravure presses utilise these solvents to carry pigments, but incomplete evaporation leaves trapped compounds in the dried ink film.
This retention happens when high run speeds outpace the drying capacity of the ovens, particularly when printing heavy ink coverage on non-porous plastic films. The trapped solvent then migrates slowly through the reel layers during storage.
Detection Method
Gas chromatography provides the standard means of measuring solvent volumes retained in printed substrates. The ethyl acetate residual is extracted from a known surface area of the packaging using headspace analysis at elevated temperatures. Calibration curves created with known solvent concentrations help quantify the exact micrograms per square metre remaining on the film.
High levels indicate inadequate ventilation or excessive line speed. This measurement ensures the packaging conforms to industry safety thresholds.
Packaging Contamination
Migrating chemicals can compromise the flavor profiles of packaged goods. When the ethyl acetate residual exceeds acceptable limits, the compound passes through the inner functional barriers of the carton to contaminate the food. This migration creates undesirable off-odours that make the product unusable.
Regulations for direct food contact restrict these solvent levels to very low concentrations.
