Whenever goods are transported in large unit loads - be it by sea, land or air - they are usually consolidated on pallets for easier handling. As a rule, products made of wood are used for this purpose. A new generation of transport pallets made of plastic is being launched onto the market by the Hirsch Group, located in Glanegg, Austria.
These pallets overcome quite a few of the drawbacks of the conventional models: among other things, they are easier to clean and very sturdy, but first and foremost, they weigh much less than EuroPallets made of wood. The highly elastic BASF styrene butadiene copolymer Styroflex 2G66 is playing a crucial role in this innovation. Engineers at Hirsch are using Styroflex 2G66 as a toughness modifier for the HIPS film (HIPS: High-impact polystyrene) that protects the lightweight core of the new pallets against damage.
Light weight - low transportation costs
Compared to conventional wooden pallets, weighing 20 to 40 kilograms, or newer metal-reinforced polyethylene pallets, the innovative products from the Hirsch Group offer the advantage of a significantly lower weight: they weigh 50 up to 75 percent less than wooden pallets or solid plastic pallets.
It is hard to estimate how many EuroPallets there are in the global flow of goods. Specialized logistics service providers employ several hundred million such pallets and, year after year, they produce tens of millions of these versatile goods carriers. All in all, the number of pallets roaming the world is probably in the order of magnitude of a few billion: that is how big the potential market is for innovative solutions.
For the purposes of lower transport costs and low carbon dioxide emissions a lightweight pallet represents a decisive environmental advantage - even if only a small part of the enormous quantity of pallets was replaced by the lightweight solution. Even the 5 kilogram pallet, the lightest variant, can handle one ton of payload, that is to say, two hundred times its own weight.
Foamed core wrapped with protective film
In order to minimize the weight of their new plastic pallet, engineers at Hirsch have developed a rigid and strong core made of expanded polystyrene for this standard transport structure. To withstand damage during the rough-and-tumble daily routine of logistical operations this structure has to be protected by a very robust skin. This is why the developers turned to a two-layer film made of BASF's impact-resistant polystyrene whose layers have Styroflex added to them. The one to two millimeters thick film wraps the pallet tightly.
HIPS made tough by Styroflex
While the special styrene butadiene copolymer serves in other applications in the form of films, in this case it is used as a toughness modifier for impact resistant polystyrene. Even in small amounts, it can considerably boost the basic toughness of HIPS, cost-effectively turning it into a material that can withstand severe mechanical stress. The Charpy notched impact strength of the basic polymer and the energy needed to puncture the product are markedly increased. As a result, the new pallets can withstand all of the jolts, impacts and shear loads normally encountered in routine logistics operations without suffering any appreciable damage.
According to BASF experience, Styroflex 2G66 also makes the material less prone to stress cracking as characterized by the so-called environmental stress cracking resistance, abbreviated ESCR. Furthermore, the addition of Styroflex 2G66 also enhances the compatibility among the materials and creates a non-slip surface. Packaged goods are much less prone to slipping on the HIPS-Styroflex film than on smooth polyethylene.
Sturdy - washable - design-friendly
In actual practice, the combination of the lightweight core with the HIPS skin entails a few more advantages. The pallets are considerably more impervious to changing weather conditions than wood and, unlike the latter, they do not absorb water. This is not only advantageous for the transportation of frozen products, where absorbed moisture unnecessarily consumes cooling capacity, but it also means that the plastic pallets do not have to be extensively treated against mold and rot. As an added bonus, occupational accidents and damage caused by splinters or protruding nails are a thing of the past.
What comes on top are hygiene aspects: the modified HIPS surface can be easily cleaned with regular power washers, which makes it the ideal transportation material for food products. Together with the requisite food contact approvals, the new pallets are also suited for the safe transportation of food. Since all of the materials involved come from the polystyrene family, it is, moreover, much easier to recycle the pallets once they have finally reached the end of their useful life.
Last but not least, from a designer's standpoint, the plastic version is much more flexible with regard to design parameters than the obdurate wooden variants. For instance, pallets sporting the colors of the customers, and even with molded indentations or printed with company logos, are all conceivable. RFID tags can easily be inserted under the protective film, so that the route traveled by pallets identified in this manner can be continuously tracked all over the world.
Double benefit in logistics
BASF's styrene butadiene copolymer has already proven itself in other respects of product logistics: In multilayered shrink-wrap or stretch hood films the material helps to effectively secure goods during loading and unloading as well as during handling at the warehouse. For this application films made from pure Styroflex are combined with polyethylene in multiple layers. Here, the product can come up with additional particular properties. Due to its remarkable recovery capacity - even after being stretched by 220 percent - the film once again clings tightly to the items. Pure polyethylene films for industrial use can only be stretched between 20 and 50 percent without loosing their stabilizing function. In the case of stretch hood films made of Styroflex the high puncture resistance together with the high crack resistance of the elastic polymer represents an additional advantage, especially when packaging sharp items.
Hence, the styrene butadiene copolymer Styroflex offers a double benefit for the transport sector - as a protective skin for new lightweight foam pallets and in stretch hood films for fixing packaged goods on the pallet. This comes all down to the fact that small amounts of a specialty plastic, the knowledge of its potential and the focused cooperation with the customer allow new economic logistics solutions to be realized.