Showa Denko K.K.
Native name
Shōwa Denkō kabushiki gaisha
Company typePublic KK
TYO: 4004
FoundedJune 1, 1939; 85 years ago (1939-06-01)
Key people
Mitsuo Ohashi (Chairman)
Hideo Ichikawa (President & CEO)
JPY 76.7 billion (2007)
JPY 1,023.2 billion (2007)
Number of employees
15,778 (2008)
Showa Denko previous logo

Showa Denko K. K. (昭和電工株式会社, Shōwa Denkō Kabushiki-gaisha, abbreviated as SDK), founded in 1939 by the merger of Nihon Electrical Industries and Showa Fertilizers, both established by a Japanese entrepreneur Nobuteru Mori, is a Japanese chemical company producing chemical products and industrial materials.

SDK's products serve a wide array of fields ranging from heavy industry to the electronic and computer industries. The company is divided in five business sectors: petrochemicals (olefins, organic chemicals, plastic products), aluminum (aluminum cans, sheets, ingots, foils), electronics (semiconductors, ceramic materials, hard disk drive platters), chemicals (industrial gases, ammonia, agrochemicals), and inorganic materials (ceramics, graphite electrodes). Showa Denko has more than 180 subsidiaries and affiliates. The company has vast overseas operations and a joint venture with Netherlands-based Montell and Nippon Petrochemicals to make and market polypropylenes. In March 2001, SDK merged with Showa Denko Aluminum Corporation to strengthen the high-value-added fabricated aluminum products operations, and is today developing next-generation optical communications-use wafers.

Showa Denko is a member of the Mizuho keiretsu.

Showa Denko is now known as Resonac.[1]


Group companies

Hard Disc Media





Electronics, other

Petrochemicals sector

The Petrochemicals Sector supports the growth of Showa Denko's basic business through the manufacture and sales of organic chemicals, olefins and specialty polymers.

SDK is the leader of the Asian ethyl acetate market. The Oita Plant, the main manufacturing base, supplies SDK and other chemical companies with the basic materials for making acetyl derivatives, synthetic resin, synthetic rubber, and styrene monomers.

Innovative products include a new heat-resistant, transparent sheet and film that can be used in flexible displays such as electronic paper and organic EL displays.

Chemicals sector

Originally focused on general-purpose industrial gases, medical gases, and industrial chemicals, SDK now provides a variety of products including high-purity gases and chemicals for the semiconductor industry. As the semiconductor industry shifted to other Asian locations, SDK established overseas specialty gases production sites in Shanghai and Singapore.

The company also offers an array of technologies and products covering various fields, including food additives, feed additives, cosmetic ingredients, medical and agricultural intermediates, optical-function materials, information-recording materials, functional polymeric materials, differentiated composite material, and liquid chromatography equipment (Shodex).

SDK recently launched an environmental initiative to reduce waste and encourage chemical recycling. In 2016 Showa Denko acquired GMM Nonstick Coatings, one of the world's largest nonstick coatings companies founded in 2007 by Ravin Gandhi. Clients included companies in the American housewares industry including KitchenAid and Calphalon,[5] in addition to foreign markets.[6]

Electronics sector

The Electronics Sector includes compound semiconductors, rare-earth magnetic alloys, solid aluminum capacitors, and hard disks.

The compound semiconductors business deals with the crystal growth process, providing a wide range of products including Ultrabright LED Chips as well as blue LED Chips.

The solid aluminum capacitor business relies on conductive polymers, a combination of inorganic aluminum materials with organic polymers. The products offer with high heat resistance and high capacitance.

The electronics sector also produces aluminum-based and glass-based hard disks as well as aluminum substrates for hard disks. In September 2008 SDK announced a consolidation their hard disk (HD) media operations by establishing a joint venture with Hoya corporation in January 2009. The joint venture was to be owned about 75% by SDK and about 25% by HOYA. However, this joint venture ended in March 2009 due to the rapid deterioration of the global economy in the Hard Disk Sector.

Inorganics sector

The Inorganics Sector consists of the Ceramics Division, Carbons Division and Fine Carbon Department.

SDK's Ceramics products are used in a wide range of fields, including chemical products, refractory products, ceramics, paper manufacture, plastics and electronics. Key products include alumina hydroxide, alumina, and high-purity alumina. SDK also produces fused alumina abrasive grains, silicon carbide and boron nitride.

SDK produces artificial graphite electrodes, an indispensable material for the recycling of steel. Other products include fine carburizing agents for iron casting.

In addition to VGCF carbon nanofibers and fuel battery materials already on the market, SDK is focusing R&D efforts on high-functionality carbon products, including battery materials, electronics materials, and materials for alternative energy solutions.[buzzword]

Aluminium sector

Condensers for automobile air conditioners are manufactured in the Showa Aluminium Czech factory in Kladno, Czech Republic

SDK produces heat exchangers, beverage cans, and other high value-added fabricated products from aluminum materials (including rolled, extruded and forged products).


Niigata Minamata disease

Further information: Niigata Minamata disease

The company is known for causing the second outbreak of Minamata disease (a type of severe mercury poisoning) in Kanose, currently part of Aga-machi, Niigata Prefecture, through the release of organomercury compounds into the Agano River.

Tryptophan contamination

In the 1980s Showa Denko applied genetic engineering to the bacteria it used in the fermentation through which it manufactured tryptophan so that the bacteria would be more efficient.[7] At the same time, they also changed the technique used to purify the tryptophan.[8]: 327–328  Multiple epidemiological studies[7][9][10] traced an outbreak of eosinophilia-myalgia syndrome (EMS) to L-tryptophan supplied by Showa Denko.[11] It was further hypothesized that one or more trace impurities produced during the manufacture of tryptophan may have been responsible for the EMS outbreak.[12][13] The fact that the Showa Denko facility used genetically engineered bacteria to produce L-tryptophan gave rise to speculation that genetic engineering was responsible for such impurities.[14] However, the methodology used in the initial epidemiological studies has been criticized.[15][16] An alternative explanation for the 1989 EMS outbreak is that large doses of tryptophan produce metabolites which inhibit the normal degradation of histamine and excess histamine in turn has been proposed to cause EMS.[17] Once the link between EMS and Showa Denko's tryptophan had been established, chemical analyses of the tryptophan was performed by researchers at the Mayo Clinic, the U.S. Food and Drug Administration (FDA), the Centers for Disease Control (CDC) and the Japanese National Institute of Hygienic Sciences to determine if any contaminants were associated with EMS.[18] Showa Denko reportedly destroyed the GM bacterial stocks after the EMS cases began to emerge.[19] In 2017, the last of the 6 contaminant associated with the 1989 EMS disease outbreak, labelled Peak AAA, has been identified using high-resolution mass spectroscopy.[20]


  1. ^ a b "Showa Denko reborn as Resonac". Retrieved 2023-03-23.
  2. ^ "Minamata Disease the History and Measures - Chapter 2 [MOE]".
  3. ^ "Showa Denko Unveils $8.8 Billion Deal for Hitachi Chemical". 18 December 2019. Retrieved 2020-08-02.
  4. ^ "Announcement of Changing Company's Name : Hitachi Chemical". Retrieved 2020-08-02.
  5. ^ "Chicagoan's GMM Nonstick Coatings acquired by Japanese chemicals giant". Chicago Tribune. 21 November 2016.
  6. ^ "GMM Cooks up Durable Nonstick Market - Middle Market Growth". Archived from the original on 2017-09-28.
  7. ^ a b Slutsker L, Hoesly FC, Miller L, Williams LP, Watson JC, Fleming DW (1990). "Eosinophilia-myalgia syndrome associated with exposure to tryptophan from a single manufacturer". JAMA. 264 (2): 213–7. doi:10.1001/jama.264.2.213. PMID 2355442.
  8. ^ Edward A Belongia, MD. Toxic Tryptophan? Investigating the Eosinophila Myalgia Syndrome in Minnesota. Chapter 26 in Cases in Field Epidemiology: A Global Perspective. Ed Mark Dworkin. Jones & Bartlett Learning, 2011
  9. ^ Back EE, Henning KJ, Kallenbach LR, Brix KA, Gunn RA, Melius JM (1993). "Risk factors for developing eosinophilia myalgia syndrome among L-tryptophan users in New York". J. Rheumatol. 20 (4): 666–72. PMID 8496862.
  10. ^ Kilbourne EM, Philen RM, Kamb ML, Falk H (1996). "Tryptophan produced by Showa Denko and epidemic eosinophilia-myalgia syndrome". The Journal of Rheumatology. Supplement. 46: 81–8, discussion 89–91. PMID 8895184.
  11. ^ U. S. Food and Drug Administration Center for Food Safety and Applied Nutrition, Office of Nutritional Products, Labeling, and Dietary Supplements. February 2001 FDA Information Paper on L-tryptophan and 5-hydroxy-L-tryptophan
  12. ^ Mayeno AN, Lin F, Foote CS, Loegering DA, Ames MM, Hedberg CW, Gleich GJ (1990). "Characterization of "peak E," a novel amino acid associated with eosinophilia-myalgia syndrome". Science. 250 (4988): 1707–8. Bibcode:1990Sci...250.1707M. doi:10.1126/science.2270484. PMID 2270484.
  13. ^ Ito J, Hosaki Y, Torigoe Y, Sakimoto K (1992). "Identification of substances formed by decomposition of peak E substance in tryptophan". Food Chem. Toxicol. 30 (1): 71–81. doi:10.1016/0278-6915(92)90139-C. PMID 1544609.
  14. ^ Mayeno AN, Gleich GJ (September 1994). "Eosinophilia-myalgia syndrome and tryptophan production: a cautionary tale". Trends Biotechnol. 12 (9): 346–52. doi:10.1016/0167-7799(94)90035-3. PMID 7765187.
  15. ^ Shapiro S (1996). "Epidemiologic studies of the association of L-tryptophan with the eosinophilia-myalgia syndrome: a critique". The Journal of Rheumatology. Supplement. 46: 44–58, discussion 58–9. PMID 8895181.
  16. ^ Horwitz RI, Daniels SR (1996). "Bias or biology: evaluating the epidemiologic studies of L-tryptophan and the eosinophilia-myalgia syndrome". The Journal of Rheumatology. Supplement. 46: 60–72. PMID 8895182.
  17. ^ Smith MJ, Garrett RH (2005). "A heretofore undisclosed crux of eosinophilia-myalgia syndrome: compromised histamine degradation". Inflamm. Res. 54 (11): 435–50. doi:10.1007/s00011-005-1380-7. PMID 16307217. S2CID 7785345.
  18. ^ Mayeno, A.; Gleich, G. J. (1994). "Eosinophilia-myalgia syndrome and tryptophan production: A cautionary tale". Trends in Biotechnology. 12 (9): 346–352. doi:10.1016/0167-7799(94)90035-3. PMID 7765187.
  19. ^ Felicity Goodyear-Smith (2001). "Health and safety issues pertaining to genetically modified foods". Australian and New Zealand Journal of Public Health. 25 (4): 371–375. doi:10.1111/j.1467-842X.2001.tb00597.x. PMID 11529622. S2CID 24737585.
  20. ^ Klaus Klarskov & Al. (2017). "Structure determination of disease associated peak AAA from l-Tryptophan implicated in the eosinophilia-myalgia syndrome". Toxicology Letters. 282 (5): 71–80. doi:10.1016/j.toxlet.2017.10.012. PMID 29037509.