Functional Layer
Protective coatings or internal treatments prevent the transfer of hydrocarbon contaminants from recycled packaging into the food content. A mineral oil migration barrier acts as a filter or a wall that stops both gaseous and liquid phase movement of aromatic and saturated hydrocarbons. These barriers are applied to the inside of a carton or integrated into the board structure during the manufacturing process.
Their efficiency is measured by the time it takes for a chemical breakthrough to occur.
Protection Mechanism
Physical blocking and chemical adsorption represent the two primary ways these layers function. A dense polymer film might provide a physical shield while a specialized coating could trap the molecules within its matrix.
Performance Verification
Validation of the effectiveness of the mineral oil migration barrier involves rigorous testing under simulated storage conditions. Tenax or other adsorbents are placed in contact with the barrier at elevated temperatures to accelerate the process. A successful barrier must maintain its integrity for the duration of the product’s shelf life.
Factors such as folding, scoring and gluing can create weak points where the barrier might fail. Manufacturers provide technical data sheets that specify the barrier’s resistance in terms of days or months. Choosing the right material depends on the fat content of the food and the expected storage temperature.
Modern solutions strive to be water based to maintain the recyclability of the paper.
