Tosoh to acquire Asahi Kasei's 50% stake in Nanyo Kasei, making HDI venture wholly owned

Tosoh Corporation will acquire all shares held by Asahi Kasei Corporation in Nanyo Kasei Co., Ltd., a 50 per cent stake, making the HDI monomer joint venture a wholly owned subsidiary of Tosoh. The B2B Marketplace reported the share acquisition on October 15, 2026. Tosoh manufactures HDI derivatives, and Nanyo Kasei manufactures HDI monomer. Asahi Kasei supplies raw materials and other inputs to Nanyo Kasei and purchases HDI monomer for its own operations.

Tosoh's Purchase of Asahi Kasei's Nanyo Kasei Stake

Nanyo Kasei was established in 1980 through equal investment by Nippon Polyurethane Industry Co., Ltd., now Tosoh Corporation, and Asahi Kasei Corporation for the purpose of manufacturing HDI (hexamethylene diisocyanate) monomer. Tosoh and Asahi Kasei currently supply raw materials and other inputs to Nanyo Kasei, which manufactures HDI monomer, and the HDI monomer produced is then purchased by each company for its respective operations.

Tosoh said the deal will secure supply for its HDI derivatives business and its new HDI derivatives plant, in commercial operation since September 2026. Through the full acquisition of Nanyo Kasei, Tosoh aims to secure a stable supply of HDI monomer and support the stable operation of its HDI derivatives business, according to the company's announcement. The transaction will also contribute to the stable procurement of HDI monomer for Tosoh's new HDI derivatives plant, which commenced commercial operations in September 2026.

Asahi Kasei Therapeutics received FDA approval for a herpes treatment it acquired early this year in an almost $1 billion deal, Endpoints News reported on October 12, 2026. The US FDA approved Asahi Kasei's pritelivir for persistent herpes simplex virus sores in immunocompromised patients unresponsive to antivirals, Yahoo reported on October 9, 2026.

Tosoh's Earlier Recycling Trial and Share Weakness

Tosoh, Shofu, Mitsui Chemicals, and Orbray launched a joint trial to recycle zirconia waste generated during the production of dental prosthetics, aiming for commercialization by fiscal year 2028, BigGo Finance reported in May 2026. Tosoh traded at ¥2,612.5, down 12.05% over 90 days, with a P/E of 14.7x versus an estimated fair P/E of 16.1x, Simply Wall St reported in September 2026. A DCF model valued the stock at ¥6,672.97, implying a significant discount.

Asahi Kasei's Benchtop Virus Filtration System

Asahi Kasei Bioprocess will unveil the VANTIJ SU-VFC Benchtop at BPI EAST 2026, a small-format benchtop system for automated, single-use virus filtration, Stock Titan reported on September 15, 2026.