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Bioplastics for Electronic Equipment

Tackling the development of biomass-based plastics -(Bioplastics) for electronic equipment-

Three-layered nano-filler for toughening bioplastic

Regarding baioplastics including polylactic acid as a base resin , further improvement in the material's toughness is required to respond to needs for smaller and thinner devices in the future. As a technology to solve this problem, we have developed a nano-sized filler, or nano-filler, with a triple-layer structure. By adding this filler to polylact nano-sized particle filler (nano filler) dramatically improving the resin's toughness.

This technology is a fundamental technology that can be adapted equally to all our high-performance bioplastic materials (polylactic acid with added kenaf fiber, flame retardant polylactic acid, shape memory polylactic acid, heat conductive polylactic acid), which I introduced previously.

The main feature of this three-layered nano-filler that we have developed is that it can form, in a self-organized fashion, nano-size particles that have different functions in the three layers. It can be formed by agglomeration and condensation of unique organic silicon compounds that have three units. Until now, a multi-stage operation of separation and recovery of the surface finishing and processing chemicals was necessary to form multi-layered filler. This operation was difficult and time-consuming, and, particularly in the case of nano-sized particles, production, was substantially difficult. Yet now with this research it has become possible for the first time to form a three-layered structure efficiently.

The structure of this nano-filler consists mainly of high-density (high rigidity) siloaxane, with an inner layer of flexible silicone rubber and an outside organic layer of caprolactam, which has a high affinity with polylactic acid. For this reason, when mixed with polylactic acid, the filler has the rigidity of conventional inorganic fillers, yet shows improvement in absorbability from its rubber layer and improvement in plasticity from its organic affinitive layer. As a result, by adding a small amount of this filler to polylactic acid (5% by weight), we were able to improve the breaking elongation by more than two times, while still maintaining the polylactic acid's strength.

Aggregation of three units of organic silicon compound + spontaneous formation of three-layered nano-filler (particles) by bridgingFig.11 Aggregation of organic silicon compound and condensation of them to form nano filler with three layers
Toughening of polylactic acid through the addition of three-layered nano-fillerFig.12 Toughening of polylactic acid through the addition of three-layered nano-filler

This technology is effective for toughening bioplastic used on exterior covering, and we believe it will help to make electronic device housing using bioplastics thinner and more durable. In particular, we aim to move forward with achieving cost reductions and optimization of the structure of this nano-filler and develop its commercial viability.

* Cross-linking: connecting chain and branched polymers and converting them into an interlocking structure, like that of a net