Single layer packs have for many years formed the bulk of food packaging, be it for bags, film or rigid containers. The reasons for this have been ease (cost) of manufacture and low cost to users (manufacturers). The disadvantages of single layer packs, are carried by both manufacturers (packers) and end users (consumers). Packers have to retract unsold stock that has passed sell by dates, this stock is then destroyed or re-processed, and the container also has to be recycled to prevent environmental harm. Consumers of course are faced with products that go off before they’re used, a waste of money and an inconvenience as well. Again the environmental impact of disposing of the products has to be considered.
Currently, for rigid packaging in multi-layer (up to 6 layers) the best option is Extrusion Blow moulding. The reasons for this are varied, but they’re extremely compelling.
- Ease of processing – The multilayer technology is built into the machine, not the moulds.
- Flexibility of mould shapes – because an extruded parison is used to blow containers different shapes are easily achieved, including punched handleware. This is not possible in a process that uses injection as its primary process.
- Colour and layer versatility – The multi-layer process lends itself to colour changes as well as layer (properties) changes. This offers the manufacturer and end user a highly versatile way to manufacture property specific containers. It would be possible to use a 6 layer system on 3 layers only, simply by changing the materials in the respective extruders, because of the nature of extrusion, there would be no impediment to that.
- In line recycling – The nature of the process allows for inline recycling of tops, tails and in the case of handle ware, punchings at the machine, where the off trims are immediately recovered before they can become contaminated, granulated and fed into the middle layers of the extrusion process resulting in no offsite reclamation of material. It also results in a zero loss position on material utilization allowing for more competitive quoting on containers by manufacturers.
- Dairy Applications – In a dairy environment, multi-layer technology can boost profits by reducing spoilage and creating a buffer to cold chain irregularities. In a South African context, this can add up to substantial profits, due to many retailers and producers outsourcing cold transport, a process which they have no control over, but in many cases have to carry the responsibility for. Extrusion also offers the aesthetic attractiveness of traditional shape packs with the advantages of multilayer technology, without resorting to squared off user unfriendly no-handle packs