History of Pallet Stretch Wrap to Date
You may not think it, but pallet stretch wrap has had a decidedly long history in the industrial packaging world. Indeed, it has become one of the fastest-growing industrial supply industries on the international market. The growth of global demand for pallet stretch wrap has been expected to increase at a steady rate of at least 5.5% each year. It comes as no surprise, then, that pallet stretch wrap has undergone a number of changes since its introduction to the chemical industry.
Early Days of Pallet Stretch Wrap
The LLDPE pallet stretch wrap as we know it today was not always in the form we manufacture it as today. Like many other plastics, initial research that began its development was mostly created by pure accident. Polyethylene itself is reported to have first been developed by Hans von Pechmann in Germany, 1898, decades before its real development began to take place fronted by the work of other chemists. It was a formation of the resin polymethylene – as it was named then – from the heating up of another chemical, diazomethane. The CH2 chains developed by this process would ignite further research and development around the world.
Industrial production for linear low-density polyethylene can be traced back as having been started in 1939 after Michael Perrin developed a process by which polyethylene could be reproduced in a stable environment. Over the next few decades, catalysts were created to further improve the polymerisation process, resulting in a variety of different levels of temperatures and pressures by which polyethylene could be produced. This included that of Karl Ziegler in 1953 and chemists at Phillips Petroleum, J. Paul Hogan and Robert Banks.
Both the Phillips and Ziegler catalysts were used for the creation of high-density polyethylene, leading to further development of its linear and low-density polyethylene form.
Industrial Development
With the plastic resins being created due to these processes, it became more apparent that industries could begin to use them for much more than solid plastic items. In fact, the linear nature of these polymers is exactly what led to the development of its thin film formation. Despite its thin appearance, the linear carbon polymers were able to hold together strongly, providing a plastic with a good tensile strength. Packaging solutions were about to become a lot more appealing to thousands of industries.
The first patent for a pallet wrapper (mechanical brake) was filed in the United States in 1967 by R. W. Burhop. This was perhaps the first real sign of stretch wrap from polyethylene being used in an industrial setting, and perhaps spurred the rest of the industry to take notice and begin the process of pallet wrapping using stretch wrap. Two forms of polyethylene were in circulation at the time; LDPE and LLDPE.
Source: dce.com.cn
LDPE has been noted as being the polymer with the lowest tensile strength and higher ductility, which means it has become more often used for industries looking for strong containers and those which are requiring a film wrap or for plastic poly bags. On the other hand, LLDPE is used for far more applications. Industries use it for not only for packaging film coverings but for other solid items including containers and even for toys.
Layering Up the Film
When pallet stretch wrap was first developed, it was created as a mono film (only one layer). By 1972, stretch film had become a staple of the pallet wrapping industry. This was the case up to the 1980s. The machine stretch wrap of 23microns was a single layer that had a stretch capacity of only around 10-15%. Ideally suitable for mechanical brake pallet wrappers. As you can imagine, this lack of flexibility alongside the development of larger pallets and containers needed to be addressed. That is where the idea of changing from mono film to multi-layered film came from.
Initially, all stretch film was made from either LDPE or PVC. Industrial professionals first assumed that the PVC was the best choice due to its 50% stretch ability, compared to 30% of LDPE, but it soon became apparent that PVC was more prone to tears and breakage than its LDPE counterpart. As such, LDPE became the focus of the global stretch film revolution. This meant that LDPE mono film was in industrial production throughout the 1970s, and changes only came in the 1980s when demands by companies for affordability and resilience of their films had to be met, introducing the newly developed LLDPE – a film far more capable of the stretch and resilience companies were looking for.
Many industries in the United States in 1982 began to create films that were three layers thick. Each layer had a different property in the film, including the middle piece for flexibility, one outer layer for clinging, and one for a smooth outside finish to the film. The stretch ability grew to 100% for a most cost-effective product. However, it was not long before more layers were added to the LLDPE process. (The reasoning for power stretch pallet wrappers).
Source: ProPurchaser.com
Demand for pallet stretch wrap only increased as usage expanded globally. Demand doubled between 1985 and 1990 to 500million lbs a year, doubling yet again in the following five years, meaning that both pricing and durability needed to be addressed for businesses to make a profit on both the supplier and consumer sides of the packaging industry. From one, to three layers, to the 1990s introducing 5-layered films. Today, stretch films are now capable of stretching up to 400% at 23microns, meaning that a single one-meter roll of film can stretch up to 5 metres without tearing. For the packaging and wrapping industries, this was the cost-effective product they were looking for.
Today’s Stretch Films
We have come a long way in the last few decades with our pallet stretch films. Extrusion technology has become so advanced that we have seen thinner 17micron films with 7 layers able to stretch up to 250%+ of their starting length. Now, as recently as 36 months ago, we are seeing the development of films with 34 layers at 12microns that can stretch up to 300% , with Nano technology.
34 layered pallet wrap films are stronger ( and have better load retention properties) than say 12 to 20 layered film with metallasoline and similar like chemicals added to give it that extra stretch ability. When any 12 micron film is stretched to 300% it is only 3 micron thick. Therefor the 34 layered film is constructed with a latticed effect which gives it, its strength, while the lessor layered films only have a linear (one direction) additive for stretch ability and strength. They are generally weaker with their load retention properties
Q.E.D. 34 layered films have the better load retention and puncture proof properties. However, a word of caution, do not expect your nearly new (2/3 years old, or certain types of new pallet wrappers, generally the bargain priced ones) with 300% power stretch to maximise the advantages of any of the 12 micron films. In short, they do not possess the stretching and especially the application technology to apply a 3 micron thick film to the load successfully. However, as every load is different, there are always exceptions to the rule. Talk to us, its free !. Tele;- 0333 123 66 66
Case Study Four Alpha 508 power stretch wrappers, processed 1000 rolls of 12 micron 34 layered film at 300% (ie one meter became four) and produced 11 million 800.000 meters of stretched film wrapping 238.000 pallets, without complaint. Cost of wrapping the pallets was only 16.78.p each (2014)
Focus Packaging can supply a 12 micron 34 layered film that will stretch to 300% and still offer high retention properties for the load also 23 micron that will stretch to 400% and plus. The Alpha 508 pallet wrapper can apply all of these types of pallet wrap, successfully to the load every time. It possesses the technology.
Advanced technical developments in the extrusion industry is starting to become more useful for the packaging industry in its development of stretch film, and it has been the tireless efforts of just two businesses in promoting these films. Their commitment to very substantial amounts of capital expenditure to purchase state of the art extruders and to commit to individual research and development projects in the user market is what has really sustained the process of creating thinner & more durable films for the market.
Thinner pallet wrap stretch films will reduce the cost of wrapping a pallet and also the amount used film to be disposed of by the end user. It will also reduce the amount of pallets that has to be bought and stored, ie a roll of 12 micron film stretched by 300% offers 11200 meters to wrap pallets, (while a 23 micron film only offers 5560 meters to wrap pallets). The operator spends less time loading the pallet wrapper and there is only half the amount of cardboard cores to dispose of. Also less money is tied up on buying the film.
We are happy to come and demonstrate the attributes of this pallet wrap if you think it’s suitable.
Thank you for taking the time to read this, I hope you found this article interesting and the information useful.
Regards. Richard Taszarek