Purac develops high heat-resistant polylactic acid resin
By Jessica Holbrook, Plastics News
Posted 27 February 2013
Bioplastics firm Purac has developed a high heat-resistant blend of polylactic acid that it says will open up new markets for bioplastic products.
Purac developed its high-heat PLA by using sterochemically pure PLA homopolymers. By combining the different polymers that make up PLA in different ways, Purac can create resin with a range of improved properties, like the ability withstand temperatures up to 356° F.
The Purac technology allows for the development of PLA that can be used as a replacement for polystyrene, polypropylene and ABS, said Francois de Bie, marketing director for bioplastics at Purac, in a presentation at the 2013 Packaging Conference.
Purac says its PLA is made from renewable raw materials, has a reduced carbon footprint, and is biodegradable.
The high-heat PLA is currently being used in several commercial applications, including injection moulded food service ware – plates, bowls, cups and utensils.
The containers are food contact approved, can be used in the microwave and dishwasher, and are heat resistant up to 100° C, so they can hold hot coffee or tea, de Bie said.
Purac has also had interest from consumer goods companies who want to use the material in luxury goods and appliances, among other applications, he said. PLA in those applications could have heat resistance up to 120° C for a short period and would be 100% bio-based.
High-heat PLA can also be used in place of polystyrene in disposable coffee cups. Using PLA does not require new equipment or processes and the line runs at the same speed when converting PLA as it does when converting polystyrene, de Bie said.
PLA is still more expensive than polystyrene, but being able to run at the same speed lessens the impact, he added.
The material can also be used to make injected moulded preforms that are then blow moulded into reusable water bottles or baby bottles. The bottles are not transparent, but the heat resistance means they can withstand boiling water and can be steam sterilized, an important consideration for baby bottles, he said.
Purac has also developed PLA foam that looks and feels identical to expanded polystyrene, he said.
The foam has high impact resistance and similar properties to PS and can be used in packaging materials, but cannot currently be used to make foam coffee cups, he said.
Purac is currently developing a transparent high-heat biaxially oriented PLA film. The film could be used to replace biaxially oriented polypropylene films, and has similar tensile and barrier properties to standard PLA films but with a high melting point of 220-250° C, de Bie said.
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