Latex offers environmentally friendly packaging
Over the past decade, researchers have sought to improve the properties of latex to serve the needs of the food packaging industry. Latex-coated wrapping can preserve food, be recovered easily within the paper recycling process and is compostable. But scientists are still struggling to make latex commercially competitive with polyethylene, though a new Swedish study has made breakthroughs in barrier coating technology.
According to Professor Lars Järnström of Karlstad University, latex has been championed for the last decade as a material that is easy to recycle. But compared with polyethylene, latex remains expensive and prone to breakdown once incorporated into packaging. Järnström and his student, Caisa Andersson, have been studying the polymerisation of latex in the hope of finding the optimum reaction conditions that create a strong and durable coating to protect food from moisture and oxidation.
“Compared with polyethylene-coated packaging, which has to be transported to a special plant to separate the polyethylene from the paper before recycling, latex can easily be separated from paper wrappings at the cellulose dissolving stage in a paper mill,” Järnström told edie. “Thus handling efficiency is increased and transportation costs are reduced. Latex is also compostable.”
But although latex coating technology also has other environmental advantages such as a heat-sealing process that eliminates the need for glue, the material is prone to tearing when handled. “When the consumer picks up a box of washing detergent, for example, the box can open because the joints are weak,” says Järnström.
“Because latex is expensive and suffers from sealability problems, we need solve these problems and offer something more to the packging industry to make it attractive.” His student has been working at the molecular level to control the transport of gases through latex food packaging, where damaging oxygen and water molecules are excluded while preservatives such as nitrogen and carbon dioxide are retained. “We are fine-tuning the mechanisms involved in barrier coating to improve the properties of latex films,” says Järnström.
Latex is also being refined to be used in packaging vegetables, a relatively new application, says Järnström. Vegatables are prone to rapid degradation from the natural release of ethylene which reduces a vegetable’s shelf-life.