Mitsui, Idemitsu, Sumitomo Polymers Merger Approved! Sumitomo Polymers Business To Be Integrated Into PRM

Mitsui Chemicals, Idemitsu Kosan, and Sumitomo Chemical reached a basic cooperation agreement on September 10, 2025. The three companies plan to integrate the polyolefin (PO) business operated by Prime Polymer Co., Ltd. (PRM), a joint venture between Mitsui Chemicals and Idemitsu Kosan, with Sumitomo Chemical's polypropylene (PP) business and linear low-density polyethylene (LLDPE) business in Japan. This integration aims to establish a core industry that supports Japan's industrial development and has strong risk resistance, enhancing the comprehensive competitiveness of PP and polyethylene (PE) businesses in Japan. On December 24, 2025, the three companies formally signed the business integration agreement and related joint venture agreements.

To advance this business integration, PRM and Sumitomo Chemical submitted a business integration plan to the Japan Fair Trade Commission in accordance with the "Act on Prohibition of Private Monopolies and Ensuring Fair Trade," and are undergoing the relevant review.

On April 24, 2026, the relevant companies have received formal notification from the Japan Fair Trade Commission, deciding not to issue a stop and rectify injunction for this integration, and the approval has been officially granted.

Currently, the merger review processes by various overseas competition regulatory authorities are still ongoing, and this business integration will be implemented after all cross-border reviews are completed.

Timeline:
September 10, 2025: Sumitomo Chemical, Idemitsu Kosan, and Sumitomo Chemical signed a memorandum of understanding to integrate Sumitomo Chemical’s polypropylene (PP) and linear low-density polyethylene (LLDPE) businesses into Prime Polymer, aiming to enhance the competitiveness of Japan’s domestic polyolefin industry.

December 24, 2025: Sumitomo Chemical, Idemitsu Kosan, and Sumitomo Chemical reached a final agreement to proceed with the integration of Sumitomo Chemical’s polypropylene (PP) and linear low-density polyethylene (LLDPE) businesses.