Bridgestone claims NR-beating isoprene

TOKYO (Feb. 24, 2017) — Bridgestone Corp. is claiming a breakthrough in polymer science that could yield a synthetic isoprene (IR) with performance characteristics surpassing those of natural rubber (NR) and which could be derived from renewable biomass.

Bridgestone said its breakthrough was achieved through the use of "precise molecular structure control" using a proprietarily developed polymerization catalyst that allowed its researchers to synthesize IR with "exceptionally high" molecular microstructure regularity similar to the levels seen in NR.

The development is in line with corporation's goal of working toward sourcing all of the raw materials used in its tires from sustainable materials by 2050. To accomplish this, Bridgestone said it is advancing research and development activities on various raw materials such as natural rubber and polyisoprene.

Natural rubber is an organic resource produced by the Para rubber tree, Bridgestone noted, and is considered a key raw material in tire production due to its superior durability and wear resistance when compared with synthetic rubber. It also exhibits strong adhesiveness with reinforcement materials.

As tire demand increases, the amount of NR consumed is projected to grow as well, Bridgestone said, and the fact that Para rubber trees can be grown only in equatorial or near-equatorial climates makes the search for NR alternatives that much more critical.

As for the new IR commercial-scale availability, Bridgestone said: "Going forward, we will evaluate the necessary conditions for the process of bringing this IR to practical application and determine how to secure a stable supply of isoprene with the aim of realizing practical application in the 2020s."

From a technical point of view, Bridgestone said its breakthrough is based on the development of a gadolinium-based catalyst that the tire maker claims can be used at temperatures above 100 degrees F, the range commonly used in polymer synthesis. Previously, Bridgestone said, Gd-based catalysts were restricted to operating environments below 32 degrees F.

Synthetic isoprene traditionally is processed using lithium (Li), titanium (Ti), or neodymium (Nd) catalysts, Bridgestone said. Using Gd-based catalysts allow for more precise control of the molecular structure of IR.

Gadolinium is a rare-earth chemical element with atomic number 64.

Besides work on a better isoprene, Bridgestone's efforts to diversify and increase the productivity of natural rubber resources include:

• Research into increasing the productivity and yield of rubber trees;

• Introduction of new agricultural materials and development of more sophisticated management techniques;

• Selection and multiplication of beneficial trees based on genome information;

• Disease prevention – Techniques for early-stage diagnosis and eradication of diseases

• Research into organic NR alternatives, such as guayule or Russian dandelions