Low-temperature polyolefin shrink wrap is a highly flexible, easily-shrunk type of tubing that was a pipe dream a few decades ago. However, innovation in the resin formulas used to produce shrink wrap means that many shrink wrapping machines can package products at as low as 65˚ Celsius for just a few seconds – though more often closer to 90˚, depending on the shrink-wrapping machine.
How Does Shrink Wrapping Normally Work?
Shrink wrapping normally takes place over three stages:
– Wrapping the product
– Shrinking the wrap
– Cooling the material
Shrinking the wrap around the product is done by applying hot air to the product, typically either by a machine or by a heat gun. Usually, products are shrink-wrapped together for wrapping purposes, but many major companies are now using shrink wrap for marketing and labelling as well.
Usually, shrink wrap applies heat between 120-130˚ Celsius around a product to contract the shrink wrap. Unsurprisingly, many manufacturers of goods that are heat sensitive are sometimes concerned about how that will affect their product.
Shrink Wrapping With PVC
Until a decade ago, the most common shrink wrap was PVC. It was (and is) commonly used in pipes, doors and windows. To make it softer and more flexible, however, PVC shrink film had to contain a plasticiser, an additive. While this massively expanded how you could use PVC, including as a shrink film, it makes it impossible to put into foods, as plasticisers are toxic to consume.
PVC shrink film is still popularly used for inedible products that are heat sensitive or fragile, like vinyl records. PVC still has the lowest shrink temperature, the widest shrink temperature range, and the lowest shrink force for wrapping flimsy products. However, the toxic and corrosive gas emission from heat sealing means that proper ventilation is required wherever one wraps with it. This makes it impossible to pack food with PVC film.
Why Polyolefin Shrink Film Changed Everything
Low-temperature polyolefin shrink film means we can offer shrink wrap machinery which can protect sensitive edible products, from fruit and produce to probiotics and gels.
Previously, fresh fruit and vegetables would have to be plastic wrapped extremely tightly – you can read about the early history of plastic wrap and the food industry on our blog – which would require extraordinarily expensive machines or painstaking manual labour. Low-temperature polyolefin shrink wrap meant you only needed to apply a heat gun for a few seconds, or that you can very quickly run your product through shrink wrapping machinery to seal your consumable before shipping it to retailers.
When is Low-Temperature Polyolefin Shrink Wrap Used?
Although it is not flame retardant, low-temperature shrink wrap gives good physical and electrical performance and is popularly used for electrical termination insulation, colour coding wires and covering heat devices among electronic engineers.
It also has a lot of use on cosmetics, where the nature of bulk production means shrink wrap would be extremely useful, but older modes of heating the wrap to seal it around the goods would damage the product. For similar reasons, other heat-sensitive products like boxes of chocolates or fruit.
Finally, low-temperature polyolefin shrink film is often used when you need to increase production times. Because the film shrinks quicker, you can feasibly shrink wrap the product faster. If the product is run through a tunnel, you can increase the conveyor speeds on the shrink-wrapping machine for higher output.
If you would like to learn more about the different types of polyolefin shrink wrap, take a look on our website or get in touch and we would be happy to give you our expert advice on the best shrink wrapping equipment.