A03034: Investigation into the applications of food contact laminated materials; examination of migration potential and recommendations for safe use

Study Duration: May 2001 to September 2003

Contractor: Rapra Technology Ltd.

Most flexible packaging, used in contact with food, has a laminate structure. This is due to demands to reduce pack weight, to improve physical properties such as strength and tear, to control the atmosphere surrounding the food. If the materials in the laminate differ in terms of polymer type, then in most cases adhesive tie-layers are required to bond the different layers together (adhesive laminating). The adhesive formulations used represent a chemistry that is chosen to withstand the processing and distribution environment of the filled product. Adhesives polymerise and/or cross-link when applied.

Although adhesive layers in laminates are behind a barrier layer of the food contacting plastic, there exists the possibility that components of the adhesive could permeate from the adhesive, through the plastic, into food. The aims of this project are to:

• Review the composition and applications of multi-layer plastic packaging and laminated materials used in different UK food-contact sectors.
• Review the composition and applications of active packaging in the UK.
• Review the manufacturing processes used for producing laminated materials.
• Identify potential migration risk situations from the above research.
• Provide validated migration data from representative test samples into food simulants and food.

The research is being undertaken with the collaboration of Industry. Migration studies will be undertaken using advanced analytical techniques on a representative selection of adhesively laminated film samples supplied by Industry.

The overall conclusion from this work was that potential migration of laminating adhesive components is only likely to be of interest if an inappropriate type of adhesive has been selected for a particular application.

• Products laminated using extrudable adhesive polymers such as polyethylene, ethylene vinyl acetate and ionomers were not considered to present any migration interest.
• Laminating adhesive is always behind a barrier film layer. The thickness of this layer, the levels of crystallinity as well as polymer type influence the migration rates of adhesive components through this layer. The rate of permeation of food or food simulant into the packaging is also controlled by the nature of the food contact layer. Because of the presence of this barrier layer between the adhesive and the food, low molecular weight mobile chemical species have the potential to contaminate food.
• Tests have been developed to help identify the nature of potential migrants from laminating adhesives. Application of the technique of liquid chromatography-mass spectrometry has significantly advanced the detection of low-level migrants from laminates into food and food simulants. The technique can also help point towards a better understanding of the chemistry of cure and chemical make-up of the adhesive.
• For those products laminated using reactive polyurethane based adhesives, suppliers have been aware for many years of the potential migration of amines formed by the reaction of unreacted isocyanate monomer with water and recommend that laminated products are given time to fully cure before they are used in contact with food. Migration experiments undertaken as part of this project have confirmed that levels of migration from cured adhesives are very low or not detectable and well within limits specified in Directive 2002/72/EC for food contact plastic materials.

Final report is available from the FSA Library and Information centre.
To obtain a copy, please contact the Enquiry Desk, Dr. Elsie Widdowson Library and Information Services, Food Standards Agency (020 7276 8181/8182 or at library&info@foodstandards.gsi.gov.uk).

Contact: For any enquiries concerning this research project, please contact the relevant Programme contact or email science@foodstandards.gsi.gov.uk