Three of Japan’s leading petrochemical firms will combine their domestic operations next April in response to growing competition and oversupply in the plastics market, Kyodo reports.

Mitsui Chemicals, Idemitsu Kosan and Sumitomo Chemical announced on September 10 that they had signed a memorandum of understanding to integrate their general-purpose plastics businesses. The move comes as prices for polyolefins – a category that includes polyethylene and polypropylene used in products such as shopping bags and car parts – have slumped due to surplus production from China.

Japan’s overall polyolefin production capacity stood at 5.83mn tonnes at the end of December, according to the Ministry of Economy, Trade and Industry.

Prime Polymer, a joint venture between Mitsui Chemicals and Idemitsu Kosan established in 2005, is the country’s largest producer of polyolefins. Under the agreement, Sumitomo Chemical’s plastics arm, currently ranked fourth in capacity, will be folded into Prime Polymer, giving the new entity control of more than 30% of domestic output.

Some production sites will be closed as part of the integration, but the firms said jobs would not be affected.

© 2025 bne IntelliNews, source Magazine