Trigger Film is the type of film that is typically used in food packaging as closures for containers. The advantages of the conventional films are that they are lightweight, easily opened and transparent. Their disadvantages are that due to their lightweight nature they are difficult to recycle cost effectively and are easily lost into the environment where they become long term pollutants.
One solution to this problem is to make the film biodegradable so that if it does become lost into the environment it can be broken down over time back into its organic components. However, the current designs of such biodegradable films can take many years to decompose and may not end up in an environment where the degrading process can work i.e. at the bottom of the ocean where there is no oxygen or the temperature is too low. Jacqueline McGlade, chief scientist at the UN Environment Programme says in a recent report on biodegradable plastics “It’s well-intentioned but wrong. A lot of plastics labelled biodegradable, like shopping bags, will only break down in temperatures of 50C and that is not the ocean. They are also not buoyant, so they’re going to sink, so they’re not going to be exposed to UV and break down,”
When used for packaging there is a conflict between the need for the film to decompose quickly after use and the need for the package to have a commercially acceptable shelf life before the package is opened which may years. Clearly a film that breaks down in air over a few months would not be acceptable as the seal on a container of dried noodles as a hole in the seal would render the product unsaleable.
Trigger Film aims to overcome these problems by providing a film that has 2 distinct phases; stable and degrading. The film is designed to remain in its stable phase from the time it is manufactured, through the process and conversion into package film and during its life as a package seal. However, at the time the package is opened the film is shifted into its degrading phase which lasts from the moment the package is opened to the end of the film's life.
By splitting the life-cycle of the film into these two distinct phases it becomes possible to achieve films with longer shelf lives and faster degradation.