Resonac
Japanese diversified chemical and advanced-materials company formerly known as Showa Denko.
Last updated October 30, 2026
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Overview
Resonac is a Japanese chemical and advanced materials company whose roots extend to the iodine, fertilizer, and industrial-chemicals businesses established by entrepreneur Nobuteru Mori in the early twentieth century. The present company was created in 1939 when Nihon Electrical Industries merged with Showa Fertilizers to form Showa Denko K.K. It operated for decades as a diversified industrial manufacturer, supplying materials and chemicals to heavy industry, construction, packaging, electronics, information technology, agriculture, and other industrial sectors. Historically, the company combined large-volume chemical manufacturing with increasingly specialized materials businesses. Its petrochemicals operations included olefins, organic chemicals, acetyl derivatives, synthetic-resin inputs, synthetic rubber materials, styrene monomers, and specialty polymers. Its chemicals activities covered industrial and medical gases, ammonia, agricultural and pharmaceutical intermediates, food and feed additives, cosmetic ingredients, specialty chemicals, and high-purity gases and chemicals used in semiconductor manufacturing. The company developed overseas production capacity for specialty gases as semiconductor manufacturing expanded across Asia. Resonac also built substantial positions in inorganic and carbon materials. These activities included alumina, high-purity alumina, fused-alumina abrasives, silicon carbide, boron nitride, graphite electrodes, carburizing agents, carbon nanofibers, fuel-cell materials, and other fine-carbon products. Such materials serve steel recycling, refractories, ceramics, electronics, batteries, and energy-related applications. Its aluminum operations historically included rolled, extruded, forged, and fabricated products, beverage cans, aluminum sheets, ingots, foils, and heat exchangers. Electronics and information-recording materials became increasingly important to the company. Showa Denko produced compound-semiconductor materials and gallium-nitride-based blue and white LED chips, rare-earth magnetic alloys, conductive-polymer solid aluminum capacitors, and hard-disk media made with aluminum and glass technologies. It also developed materials intended for emerging display and optical-communications applications. These activities placed the group between traditional bulk chemicals and higher-value materials used by the semiconductor, data-storage, display, and communications industries. A major strategic change came with the acquisition of Hitachi Chemical, announced in 2019 and completed as part of the expansion of the group’s battery and advanced-materials capabilities. Hitachi Chemical was renamed Showa Denko Materials in 2020. Showa Denko and Showa Denko Materials were subsequently combined in January 2023, and the company adopted the Resonac name. The rebranding expressed an ambition to operate as an integrated specialty-chemicals and materials supplier rather than primarily as a conventional diversified chemical producer. The group has also expanded through subsidiaries, affiliates, joint ventures, and overseas manufacturing operations. Its historical businesses included petrochemicals, aluminum, electronics, chemicals, and inorganic materials, with products sold to industrial and technology customers rather than mainly to consumers. Resonac’s portfolio therefore spans basic chemical intermediates and industrial materials as well as high-purity semiconductor inputs, battery materials, electronic components, carbon products, and other functional materials. The company’s history also includes serious environmental and product-safety controversies, notably mercury pollution associated with the Agano River and the late-1980s eosinophilia-myalgia syndrome outbreak linked to Showa Denko-supplied L-tryptophan. These episodes remain important parts of the company’s historical record.
History
Resonac traces its corporate history to businesses founded by Nobuteru Mori. In December 1908, Mori established Sobo Marine Products in Chiba Prefecture to manufacture and sell iodine. That business developed into Nihon Iodine, which was formally established in October 1926. Mori also founded Showa Fertilizer in April 1928. The fertilizer company opened Japan’s first ammonium-sulfate factory in April 1931, establishing an industrial base that later became central to the Showa Denko group. Nihon Iodine changed its name to Nihon Electrical Industries in March 1934. In June 1939, Nihon Electrical Industries and Showa Fertilizer merged to create Showa Denko K.K. The new company expanded across chemicals and industrial materials and was listed on the Tokyo Stock Exchange in May 1949. It received the first Deming Prize in September 1951, an early recognition of its quality-management practices. During the postwar industrial expansion, Showa Denko developed petrochemical, fertilizer, inorganic-materials, aluminum, electronics, and industrial-gas operations. Its Oita Petrochemical Complex began commercial operations in April 1969, and a second ethylene-capacity expansion was completed there in March 1977. The company later withdrew from domestic aluminum smelting in February 1986 while retaining and developing higher-value fabricated aluminum activities. It completed its first hard-disk plant in Chiba in November 1989, reflecting the group’s growing involvement in information-recording materials. The company’s history also includes major environmental and product-safety controversies. In the late 1960s, mercury pollution associated with the company caused the second major Minamata-disease outbreak in Japan along the Agano River in Niigata Prefecture. In the 1980s, an outbreak of eosinophilia-myalgia syndrome was linked through epidemiological investigations to L-tryptophan supplied by Showa Denko. Investigators examined manufacturing changes and trace contaminants; debate continued over the precise mechanism and the relevance of the genetically engineered bacteria used in production. Showa Denko pursued quality and environmental-management systems during the 1990s. Omachi Works obtained ISO 9001 certification in January 1995, and its Production Technology Center obtained ISO 14001 certification in May 1997. In March 2001, the company merged with Showa Aluminum Corporation, strengthening its fabricated-aluminum portfolio. In 2003, polyethylene activities of Japan Polyolefins and Japan Polychem were integrated into a new joint venture. The following years brought further expansion in hard-disk media, compound semiconductors, aluminum products, specialty gases, rare-earth alloys, carbon materials, and overseas manufacturing. Showa Denko announced a medium-term business plan called the PASSION Project for 2006–2008. It opened or expanded plants for aluminum cylinders, hard-disk media, and neodymium-based alloys, and developed crystal-growth technology for gallium-nitride blue and white LEDs. It also entered and consolidated businesses in specialty coatings, carbon materials, electronic components, and other differentiated products. A proposed 2009 hard-disk-media joint venture with Hoya was abandoned after the global hard-disk market deteriorated. The company’s next major transformation began with its acquisition of Hitachi Chemical, announced in December 2019 for the purpose of scaling its lithium-ion-battery and advanced-materials businesses. Hitachi Chemical was renamed Showa Denko Materials in June 2020. In January 2023, Showa Denko K.K. and Showa Denko Materials merged to form Resonac. The new name and integrated structure were intended to support a more focused identity as a specialty-chemicals and advanced-materials group. Resonac’s inherited portfolio spans petrochemicals, aluminum, electronics, industrial and high-purity chemicals, ceramics, graphite, carbon products, semiconductor materials, hard-disk media, and battery-related materials.
- 2023
Resonac formed
[1]Showa Denko and Showa Denko Materials merged, and the combined company adopted the Resonac name.
- 2020
Hitachi Chemical becomes Showa Denko Materials
[1]The acquired company adopted the Showa Denko Materials name.
- 2019
Hitachi Chemical acquisition announced
[1]Showa Denko announced the acquisition of Hitachi Chemical to expand advanced-materials and battery activities.
- 2005
Perpendicular-recording hard-disk media
[1]The company began production of hard-disk media using perpendicular magnetic-recording technology.
- 2001
Merger with Showa Aluminum
[1]Showa Denko merged with Showa Aluminum Corporation to strengthen fabricated and higher-value aluminum operations.
- 1989
Hard-disk plant completed in Chiba
[1]Showa Denko completed its first hard-disk plant in Chiba.
- 1969
Oita Petrochemical Complex begins operations
[1]The Oita complex entered commercial operation and became a major base for petrochemical production.
- 1968
Agano River mercury pollution
[1]Mercury pollution associated with the company caused the Niigata Minamata disease outbreak.
- 1951
Receives the first Deming Prize
[1]The company was awarded the first Deming Prize for quality-management achievement.
- 1949
Listed on the Tokyo Stock Exchange
[1]Showa Denko became a publicly listed company in Japan. Showa Denko was listed on the Tokyo Stock Exchange.
Products and positioning
An integrated Japanese specialty-chemicals and advanced-materials supplier serving industrial, semiconductor, electronics, energy, mobility, and infrastructure value chains. A diversified Japanese chemicals and advanced-materials group positioned between large-scale industrial manufacturing and high-value electronic, semiconductor, battery and carbon-material applications.
Petrochemicals
Petrochemicals
The petrochemicals portfolio includes olefins, organic chemicals, acetyl derivatives, synthetic-resin inputs, synthetic rubber materials, styrene monomers, and specialty polymers. The Oita complex supplies basic intermediates used by Resonac and other manufacturers. The business has historically included a strong position in Asian ethyl acetate and related chemical value chains. The company has also developed heat-resistant transparent sheets and films intended for applications such as flexible displays and organic-electroluminescent display technologies. Resonac’s petrochemical portfolio includes olefins, organic chemicals, acetyl derivatives, specialty polymers and other basic inputs used in synthetic resins, rubber and industrial manufacturing. The Oita complex is a major production base and supports both Resonac’s internal value chain and external customers. The company has also developed heat-resistant transparent sheets and films intended for applications such as flexible displays and organic-electroluminescent display technologies.
Industrial and electronic chemicals
High-purity gases and chemicals
Resonac supplies industrial and medical gases as well as high-purity gases and chemicals used in semiconductor manufacturing. The group developed overseas specialty-gas production sites as semiconductor production expanded in Asian markets, including facilities associated with Shanghai and Singapore. Related chemical activities include ammonia, agricultural intermediates, food and feed additives, cosmetic ingredients, and medical intermediates.
Electronics materials
Semiconductor and electronic materials
The electronics portfolio has included compound semiconductors, gallium-nitride-based blue and white LED chips, rare-earth magnetic alloys, conductive-polymer solid aluminum capacitors, and other materials for electronic devices. These products address semiconductor, optoelectronic, information-recording, and communications applications.
Information-recording materials · 1989
Hard-disk media
Showa Denko developed aluminum- and glass-based hard-disk media and substrates. Its Chiba operations and later overseas facilities supported the group's role in data-storage materials, including production based on perpendicular magnetic-recording technology.
Inorganic materials
Ceramics and alumina
The ceramics business produces alumina hydroxide, alumina, high-purity alumina, fused-alumina abrasive grains, silicon carbide, and boron nitride. These materials serve refractories, ceramics, paper, plastics, chemicals, and electronics applications.
Carbon materials
Graphite and fine-carbon materials
Carbon activities include artificial graphite electrodes used in electric-arc steelmaking, fine carburizing agents for iron casting, vapor-grown carbon nanofibers, fuel-cell materials, and other functional carbon products intended for batteries, electronics, and alternative-energy applications.
Aluminum materials and packaging
Aluminum products
The aluminum business has included beverage cans, rolled sheets, ingots, foils, extruded and forged products, heat exchangers, and other fabricated materials. The 2001 merger with Showa Aluminum strengthened the company’s higher-value fabricated-aluminum activities. The aluminum business covers beverage cans, rolled products, sheets, foils, ingots, extruded and forged materials, heat exchangers and other fabricated components. After withdrawing from domestic primary aluminum smelting, the group concentrated more heavily on processing and higher-value-added products for packaging, transportation, industrial equipment and other applications.
Energy and advanced materials · 2019
Battery and advanced materials
The acquisition and integration of Hitachi Chemical expanded the group's exposure to lithium-ion-battery materials and advanced materials. These activities became central to the strategic rationale for combining Showa Denko Materials with Showa Denko under the Resonac name.
Chemicals
Industrial and semiconductor gases
The gases business spans general-purpose industrial gases, medical gases and high-purity gases and chemicals for semiconductor production. As semiconductor manufacturing expanded across Asia, the group established overseas specialty-gas production capabilities, including facilities associated with Shanghai and Singapore. These materials support controlled-atmosphere processing, deposition, etching and other demanding manufacturing steps.
Inorganic materials
Graphite electrodes and carbon materials
Resonac produces artificial graphite electrodes used in electric-arc furnaces for steel recycling, together with fine carburizing agents and other carbon products. Its fine-carbon activities include vapor-grown carbon nanofibers, fuel-cell materials and research into high-functionality carbon materials for batteries, electronics and alternative-energy applications. These activities connect the company’s traditional inorganic-materials base with newer energy and electronic-materials markets.
Ceramics
Ceramics and high-purity alumina
The ceramics portfolio includes alumina hydroxide, alumina, high-purity alumina, fused-alumina abrasive grains, silicon carbide and boron nitride. These materials serve refractory products, chemical processing, paper, plastics and electronics. High-purity grades are particularly relevant to advanced processing and electronic applications where contamination control and thermal performance are important.
Electronics materials
Electronic materials and hard-disk media
Resonac’s electronics activities include compound-semiconductor materials, blue and ultraviolet LED-related products, rare-earth magnetic alloys, conductive-polymer aluminum capacitors, aluminum and glass hard-disk media and hard-disk substrates. The business has historically invested in crystal-growth technology, magnetic-recording media and materials designed for high heat resistance, high capacitance and demanding information-storage applications.
Laboratory equipment
Shodex analytical systems
Shodex is associated with Resonac's liquid-chromatography equipment and analytical-materials activities. These products support laboratory separation and analysis across pharmaceutical, chemical, food, environmental and research applications. The offering complements the group's broader portfolio of specialty chemicals and functional materials.
Controversies
1989
L-tryptophan and eosinophilia-myalgia syndrome
An outbreak of eosinophilia-myalgia syndrome was linked by multiple epidemiological studies to L-tryptophan supplied by Showa Denko. Investigations examined changes in fermentation and purification processes and identified trace impurities as a possible cause. The role of genetically engineered production bacteria was widely debated, but the reference notes that the initial causal interpretation was contested. L-tryptophan manufactured by Showa Denko was linked by epidemiological investigations to an outbreak of eosinophilia-myalgia syndrome. Investigators examined changes to fermentation and purification processes and identified trace contaminants as a possible explanation. Later research also questioned some aspects of the original causal interpretation and considered alternative biological mechanisms.
1968
Niigata Minamata disease
Showa Denko was associated with the second major Minamata-disease outbreak in Japan after organomercury pollution entered the Agano River in Niigata Prefecture. The contamination caused severe mercury poisoning among affected communities and remains one of the company’s most serious environmental controversies. Showa Denko was associated with organomercury pollution in the Agano River basin in Niigata Prefecture. The contamination caused severe mercury poisoning among affected communities and became known as Niigata Minamata disease.
Brand decisions
2023
Adopt the Resonac identityStrategyBackground
The merger of Showa Denko and Showa Denko Materials created a larger group with chemicals, electronics, battery, and advanced-materials activities.
Action taken
The combined company adopted the Resonac name and repositioned itself around specialty chemicals and advanced materials.
Aftermath
The rebrand marked the company’s transition away from an identity centered on the former Showa Denko corporate name.
2023
Formation of ResonacStrategyBackground
The group sought to integrate Showa Denko’s chemical and industrial-materials portfolio with the advanced-materials businesses acquired from Hitachi Chemical.
Action taken
Showa Denko K.K. and Showa Denko Materials merged and adopted the Resonac name.
Aftermath
The combined company operates across chemicals, carbon, electronics, semiconductor, battery, aluminum and other advanced-materials fields.
2019
Acquire Hitachi ChemicalM&ABackground
Showa Denko aimed to increase its scale in lithium-ion batteries and advanced materials.
Action taken
Showa Denko agreed to acquire Hitachi Chemical. The company announced an acquisition of Hitachi Chemical.
Aftermath
Hitachi Chemical became Showa Denko Materials in 2020 and was later combined with Showa Denko in the formation of Resonac.
2001
Merge with Showa AluminumM&ABackground
Showa Denko sought to reinforce its aluminum businesses, particularly higher-value fabricated products.
Action taken
Showa Denko merged with Showa Aluminum Corporation.
Aftermath
The transaction broadened Showa Denko’s aluminum portfolio to include additional fabricated and packaging-related operations. The merger expanded the group’s integrated aluminum-materials and fabricated-products capabilities.
1986
Withdrawal from domestic aluminum smeltingStrategyBackground
Showa Denko’s aluminum activities were being reshaped away from domestic primary smelting and toward processed and fabricated products.
Action taken
The company withdrew from its domestic aluminum-smelting business while retaining and developing aluminum-processing operations.
Aftermath
The change supported a longer-term emphasis on higher-value-added aluminum materials and components.
Recent events
- 2023
Showa Denko and Showa Denko Materials merge to form Resonac[1]
M&A · Leadership change · Other
The two companies completed their merger and began operating as Resonac, combining the legacy Showa Denko portfolio with Hitachi Chemical’s advanced-materials businesses.
- 2020
Hitachi Chemical renamed Showa Denko Materials[1]
M&A · Other
Following the acquisition, Hitachi Chemical adopted the Showa Denko Materials name as part of its integration into the group.
- 2019
Showa Denko acquires Hitachi Chemical[1]
M&A
Showa Denko agreed to acquire Hitachi Chemical in a transaction intended to expand its lithium-ion battery and advanced-materials businesses.
Sources2 sources
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