Human Wisdom to Achieve Industrial Application of Electron Beams

In 1952, Professor Arthur Charlesby, a physicist in the U.K., discovered a highly unique phenomenon: cross-linking of polyethylene was achieved by electron beam irradiation. This heralded the widespread use of the irradiation and cross-linking process in industrial fields. Cross-linking refers to a chemical reaction that creates new intermolecular bonds by irradiating high-energy electron beams on resins such as polyethylene. This attains characteristics such as heat resistance, oil resistance, chemical resistance, and shape memory effects. Today, this is a very important process to improve the characteristics of polymer materials such as plastics and rubber. Products derived from this process are used in various fields including electric home appliances and automobiles.

The Sumitomo Electric Group was quick to pay attention to the irradiation and cross-linking process. It started research in the 1950s, and launched a joint project with Nissin Electric Co., Ltd. (“Nissin Electric”) in 1957 to develop the electron beam accelerator. In 1960, the first electron beam accelerator for research was set up. In the same year, power cables derived from the process were delivered to an electric power company. Subsequently, the group offered various products as a pioneer of the process to variety of manufacturing industries in Japan. To meet the changing needs of the times and society, the process has evolved over the years. This issue focuses on the history of the irradiation and cross-linking business of the Sumitomo Electric Group, and introduces the current applications and a bright future to be achieved by the process.