Differing from conventional PLA, which is comprised solely of poly-L-lactic acid polymer, stereocomplex PLA also contains the poly-D-lactic acid enantiomer. This results in a melting point that is more than 40°C higher than standard PLA, putting Biofront's heat resistance on a par with petroleum-derived polybutylene terephthalate (PBT).
Boston Club expects to sell 2000 pairs of the eyeglasses annually. Most pairs of eyeglass frames weigh 25 grams or a bit less, so the volume discussed here is small. For Teijin, though, it is an opportunity for its material to see use in a high visibility application (pun intended).
As we reported last year, Teijin aims to make about 5000 tons of the Biofront material in its fiscal 2011 and eventually reach several tens of thousands of tons. Here is some additional information on Teijin's Biofront PLA material, which in addition to its higher melting point offers at least 10 times more hydrolytic resistance than conventional bioplastics.
Teijin says the material also is highly resistant to bleaching and bacteria, has good hydrolytic stability and achieves semi-crystallization in just 20-25% of the time required by conventional PLA, making it an excellent choice for many molded-plastic applications.
In 2009, Teijin collaborated with Tanaka Foresight Inc., which manufactures and sells approximately 60% of all plastic eyeglass parts in Japan, to develop eyeglass frames made from Biofront.
Acetate is commonly used for the plastic parts of eyeglasses, but contact with cosmetics or hair-styling products can bleach the material.