- January 11, 2013
MEERHOUT, BELGIUM | The ExxonMobil Chemical polymer plant in Meerhout is introducing a more sustainable stretch hood film solution to its packaging operations. The new stretch hood solution with Vistamaxx propylene-based elastomer (PBE) keeps not only 25kg sacks of polymer pellets secure and stable on the pallet, but also allows for up to 16% reduction of material use, thus helping to lower costs.
Until 2004, the Meerhout Polymer Plant (MPP) used shrink hood packaging for pallet unitization and load protection. A stretch hood solution was then introduced to improve load stability, enhance safety as no open flame is required, and reduce costs as a thinner film could be used.
The stretch hood film formulation being used was 100% Exceed metallocene polyethylene (mPE) resin in the outer layers with 100% Nexxstar ethylene vinyl acetate (EVA) copolymer resin in the core layer. This 100-micron film provided high holding force, load stability, tear and puncture resistance, seal strength, and weather protection.
adding Vistamaxx PBE
Committed to the principles of sustainability, ExxonMobil Chemical wanted to develop a new stretch hood film formulation that used less material and reduced costs, while maintaining effective stability and protection of the polymer sacks on the pallet. In addition, having established a stretch ratio target of 55% on the pallet, a more flexible film solution was needed.
ExxonMobil Chemical turned to its Vistamaxx PBE as it can be used to deliver new levels of performance, processing efficiencies and lower formulation costs for flexible films. Vistamaxx PBE can enhance targeted properties, such as elasticity, flexibility, adhesion, sealability, cling, toughness, and clarity, for specific applications.
Extensive formulation development, trials, and testing resulted in a new stretch hood film solution. The three-layer film structure comprised 100% Exceed mPE resin in the outer layers and 15% Vistamaxx PBE and 85% Nexxstar EVA copolymer resin in the core.
The Exceed mPE resin-based skin layers deliver toughness, improved resistance to hole formation and tear propagation in addition to superior optical properties. Nexxstar EVA copolymer resins provide high holding force and stretch capability. The addition of Vistamaxx propylene-based elastomer (PBE) in the core layer allows softness and elastic recovery to be enhanced.
Tests indicated that this formulation provided the optimum performance for this application. The film was produced by Selene SpA based in Italy.
“Compared to standard EVA-based films, the addition of Vistamaxx PBE provides good opportunities to downgauge stretch hood films and improve the flexibility. We tested a Vistamaxx PBE-based film at MPP that covers standard pallets of polymer bags. In this case, Vistamaxx PBE saved almost 20% of packaging material, without losing pallet stability,” said Marco Rubertà, Technical Department and R&D, Selene SpA.
10% thinner films with similar performance
The film met the stretch ratio target of 55% and was thinner, having been downgauged from 100 micron to 90 micron. This resulted in 16% raw material savings.
Pallets using the downgauged stretch hood film were successfully tested by ESTL nv, Deerlijk, Belgium, and certified as stable according to EN 12195-1.
The load stability tests simulated a truck, loaded with a pallet unit, having to make an emergency stop. During the test, the pallet is accelerating at 0.5G. The acceleration of 0.5G is comparable to the force applied to the pallet during an emergency stop of a truck.
The change in shape of the pallet unit was then measured. The tests showed that the new stretch hood film was as effective as the original film in providing load stability. Puncture tests confirmed that the 90 micron film provided as much protection as the 100 micron film.
Frank Bruhn ApS, an independent specialist in stretch hood machinery based in Denmark, helped ExxonMobil Chemical optimize the running of the film in Meerhout.
“At MPP in Belgium, we put a thinner Vistamaxx PBE-based stretch hood film into the production line. The result was the same high quality protection and load stability as with the thicker film previously used. I am convinced that many of my customers will be able to save up to 100 grams of film per pallet load with the new Vistamaxx PBE-based stretch hood film,” said Bruhn.
The stretch hood film is now commercial at the MPP plant, with ExxonMobil Chemical planning to introduce it to other polymer plants in its global network. The company also believes the success of Vistamaxx PBE-based stretch hood film at MPP can be extended into other stretch hood applications.
“I expect interest in the new Vistamaxx PBE-based film by stretch hood users globally. At a time when companies are looking at cost optimization, the new film can meet these demands through its downgauging capabilities which will be highly valued by customers,” said Bruhn. “Appliances are another application where stretch hood technology growth is accelerating. We have experienced good results using Vistamaxx PBE-based film formulations because they offer flexibility, better “snap-back” and excellent optical properties,” said Rubertà.