
Why is Japan’s petrochemical giant Maruzen shutting down a key ethylene plant after 50+ years? The answer reveals a bigger shift in the industry.
The Big Decision
Japan’s Maruzen Petrochemical, part of Cosmo Energy Holdings, announced on April 1 that it will shut down its ethylene production unit in Chiba by the 2026/27 financial year.
The move is part of a consolidation plan with its joint venture, Keiyo Ethylene (55% owned by Maruzen, 45% by Sumitomo Chemical), to cut costs and stay competitive.

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Why Now?
The Japanese ethylene industry is under pressure. Global oversupply, especially from China’s massive new plants, and shrinking local demand have slashed profits.
On top of that, companies face strict net-zero carbon targets, pushing them to streamline operations.
Maruzen’s Chiba unit, operating since 1969, can produce 525,000 metric tons yearly—but Keiyo Ethylene’s newer facility (768,000 tons/year) is more efficient. By merging production, Maruzen and Sumitomo aim to boost output rates and reduce expenses.
A Trend in the Industry
This isn’t the only consolidation in Japan. Last year, Idemitsu Kosan and Mitsui Chemicals also announced plans to merge their Chiba ethylene plants.
Ethylene, a key ingredient for plastics like polyethylene (used in bags and containers), remains vital—but only the strongest players will survive the current market crunch.
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