New additive improves strength of PLA, says Rohm and Haas
The company said that the additive, Paraloid BPMS 250, complies with EU Directive 2002/72/EC and US Food and Drug Administration (FDA) requirements.
Rohm and Haas claims that the packaging industry's move toward PLA resin has been hampered by unmodified PLA being somewhat weaker and more brittle than traditional materials.
Robert Martin, plastic additives marketing manager, Rohm and Haas, told FoodProductionDaily.com that BPMS 250 was developed in collaboration with US manufacturer of PLA, NatureWorks.
“NatureWorks asked us to render their material tougher so that their equipment would run more rapidly. PLA can break easily as it is brittle and this leads to problems such as web sagging and necking that can lower processing speeds.
“BPMS 250 eliminates these difficulties by adding higher melt strength during the film, sheet and blown film extrusion of PLA,” claims Martin.
He said the modified PLA can be used to package a wide range of food products from meat to dairy and that adding only two per cent of the acrylic additive to PLA increases the melt elasticity of the blend without affecting the clarity of the final product.
PLA is popular with food companies wanting to swap plastic packaging for biomass polymer-based alternatives to stress their green credentials.
It can be used in clear packaging applications such as thermoform or vacuform disposable clamshell-type food containers.
Disposability
According to NatureWorks, its PLA can be physically recycled, composted through industrial processes, incinerated via waste to energy systems, and also chemically recycled back into its base monomer unit of lactic acid.
However, Martin concedes that the biopolymer, which is derived from corn starch, is still more expensive than the polyethylene terephthalate (PET) that it is designed to replace.
Chris Noble, an analyst at UK-based market analysts Applied Market Information, AMI, said of all the bioplastics, PLA is the best established.
The leading European manufacturer of the polymer is Novamont and its Mater-Bi polymer will home-compost, giving it a far better chance of a wide take-up, claims Noble.
Food prices
He said that the current debate over food prices is having an impact on the expansion of food-based plastics and, in terms of growth, the biopolymer market is very difficult to predict.
"The wider political issues are complex," said Noble. "Should arable land be used to grow crops for plastic, or should we concentrate on feeding the world?"
He claims that food-based plastic is currently a niche area with critics arguing that the supermarket chains are simply exploiting the guilty environmental consciences of the middle class.
"However, these consumers are extremely powerful and growth could explode. The bottom line is it's all about oil and food," added Noble.
