Chemical
Tosoh set to take full control of HDI monomer joint venture, secures supply for new plant
Tosoh and Asahi Kasei supply raw materials and other inputs to Nanyo Kasei
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By ICN Bureau | October 15, 2026
Tosoh Corporation is ready to take full ownership of Nanyo Kasei Co., Ltd., acquiring Asahi Kasei Corporation’s 50% stake in the joint venture to strengthen HDI monomer supply and support the expansion of its derivatives business.
The acquisition will make Nanyo Kasei a wholly owned subsidiary of Tosoh, ending the equal-shareholding arrangement between the two Japanese chemical companies.
Established in 1980 by Nippon Polyurethane Industry Co., Ltd. — now Tosoh Corporation — and Asahi Kasei, Nanyo Kasei was created to manufacture hexamethylene diisocyanate (HDI) monomer, a key raw material for downstream derivatives.
Under the existing arrangement, Tosoh and Asahi Kasei supply raw materials and other inputs to Nanyo Kasei, which manufactures HDI monomer. Both companies then purchase the output for their respective operations.
By acquiring Asahi Kasei’s entire 50% stake, Tosoh aims to strengthen its control over the HDI monomer supply chain and ensure a stable supply to support the continued operation of its HDI derivatives business.
The move is also intended to secure supplies for Tosoh’s new HDI derivatives plant, which commenced commercial operations in September 2026.
The acquisition underscores Tosoh’s focus on strengthening raw-material security and supporting the stable operation of its expanding HDI derivatives business.
