Termination of Styrene Monomer Production Business at our Yamaguchi Operations


Taiyo Oil (President & CEO: Yutaka Oka) has decided to terminate the styrene monomer production business at its Yamaguchi Operations.

The Company took over the styrene monomer manufacturing business from Mitsui Chemicals, Inc. and opened the Yamaguchi Operations plant in January 2004. Since then, the plant has responded to domestic and international demand by aggressively expanding and streamlining its facilities. However, with the rapid progress of carbon neutrality-related initiatives worldwide in recent years, the importance of building a sustainable business structure for the future is increasing, and at the same time, the styrene monomer market is expected to continue to face an uncertain business environment in the future, as new manufacturing plants are being built one after another, mainly in China.

In light of this business environment, we have long been considering every possible way to establish an optimal business structure. Based on the possibility of utilizing the management resources of the Yamaguchi Operations, including its land and facilities, in a new business, we have decided that the best course of action is to cease styrene monomer manufacturing and to transform the site into another business location. The specific timing of the termination of the business will be determined in due course, taking into consideration various circumstances.

The Company will consider all business options for the future use of this location that will contribute to the creation of new value for Taiyo Oil and the region. In addition, all employees working at the business will continue to be employed by the Company.

Outline of the Yamaguchi Operations


13-3 Nishioki, Nishiokinoyama, Ube City, Yamaguchi Prefecture

Start of operations

April 1994


Hideo Kumon (Executive Officer)

Number of Employees

65 (as of Dec 1, 2022)

Site Area


Production facilities

Ethylbenzene production equipment capable of outputting 397,000 tons/year

Styrene monomer production equipment capable of outputting 370,000 tons/year