vulnerable profiles of items. Not specifically used in food packaging but widely used in products associated with the cooking and storage of food • Moulded pulp applications (already mentioned under Section 8.8.11 above for eggs and apples). 8.8.15 Cap liners (wads) and diaphragms There are a number of ways of ensuring a good seal when a lid is applied to a jar, bottle or similar rigid container. • Pulpboard disk. The simplest type of cap liner is a pulpboard disk made from mechanical pulp fitted inside a plastic cap. This cap liner or wad has to be compressible and inert with respect to the contents of the container. This liner could be faced with aluminium foil or PE where the nature of the contents require separation from direct contact with the pulpboard. • Induction sealed disk. The disk comprises pulpboard/wax/alumium foil/ heat seal coating or lacquer. The cap with the disk in place is applied to the container and secured. It then passes under an induction heating coil. This heats the aluminium foil which causes the wax to melt and become absorbed in the pulpboard. It also activates the heat seal coating and seals the aluminium foil to the perimeter of the container. When the consumer removes the cap the adhesion between the pulpboard and the aluminium foil breaks leaving the foil attached to the container. This seal therefore provides product protection and tamper evidence. Where subsequent contact between the contents and the pulpboard is undesirable, the pulpboard is permanently bonded to the aluminium foil. (A simpler version dispenses with the wax and replaces the pulpboard with paper.) 8.9 Systems
There are many examples today of a total systems concept involving one packaging company acting in partnership with the food manufacturer in an integrated system from the point of packing and processing to the point of sale.
Paper and paperboard based packaging systems for food products implies consideration of:
• the functional needs of packaged preserved foods
• how these needs are met by paper and paperboard based materials and the packaging made from such materials • packaging machinery
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