Biopolymers: Polylactic acid and flame retardancy

Biopolymers have gained much attention, because they are based on "renewable carbon" in place of "fossil carbon". Polylactic acid (PLA) is a commercially available biopolymer gained by fermentation of biomass such as corn and potatoes with production sites in the USA, China and Japan.

Another big motivation for using biopolymers is to meet a Japanese government directive that 20% of all plastics used in Japan must be bio-derived by 2020. This directive opened the way for partly bio-based resins-alloys or blends of bio- and petrochemical materials, which both reduce the overall "carbon footprint" and improve the biomaterial's properties.

In Japan, a laptop computer cover has been developed, using a 50/50 PLA/PC blend and flame-retardant additives. The 50/50 blend is claimed to have the processability, heat resistance, and flame resistance required for larger IT devices.

In addition, a bio-based plastic with flame retardance for multifunction office systems is currently developed by several Japanese IT companies. The material - which includes more than 25% of PLA biopolymer - achieves the most demanding level of flame retardance, 5V, according to UL 94 flammability tests. Examples of flame retardant systems used for PLA are silicon resins, metal hydroxides such as aluminium trihydrate, ammonium polyphosphate, as well as other phosphorous and nitrogen compounds as components of intumescent systems.

It is planned to use approximately 100 tons of the material per year. Compared with conventional petroleum-based plastics used in multifunction office systems, this new bio-based compound offers an expected reduction in manufacturing-related CO2 emissions of approximately 20%.

The development of the new bio-based plastic will enable its use not only for select parts in multifunction office systems, but also for replacing petroleum-based plastics used for exterior parts, which require a high level of flame retardance.