Nihon Tokushu Rozai Co., Ltd.
Japanese specialist manufacturer of monolithic (unshaped) refractories, including castables, plastic refractories and special refractory mortars.
Last updated September 29, 2026
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Overview
Nihon Tokushu Rozai Co., Ltd. (often abbreviated as Nitoro) is a Japanese manufacturer of monolithic, or unshaped, refractories. The company is headquartered in Tamano, Okayama Prefecture, and describes itself as a specialist maker of monolithic refractories, supplying products and related peripheral technologies to industries that operate high-temperature furnaces. Its product range includes castable refractories, plastic refractories, special refractory mortars, acid-resistant cements and other acid-resistant materials, as well as precast shaped castable blocks. Beyond materials, the company designs and constructs industrial furnaces, carries out and manages furnace masonry work, and sells or leases kiln and furnace repair machinery and combustion equipment. The company traces its origins to 1924, when Kato Hisashi founded the Kato Acid-Resistant Refractory Materials Research Institute in what was then Uno Town, Kojima District (now part of Tamano City, Okayama Prefecture). That venture developed "Permatite," described as Japan's first air-setting mortar for refractory bonding, and later acid-resistant mortar products such as "Asipulfite." In 1931 the business merged with Uno Refractory Brick Co., Ltd. and continued manufacturing as that company's special products section. In 1944 the special products section merged with Endo Goshi Kaisha to establish Nihon Tokushu Rozai Co., Ltd. After the Second World War the company expanded its product line and its sales network. It began manufacturing and selling the castable refractory "Permacast" in 1954 and the plastic refractory "Permaplast" in 1960. In 1959 it contracted Kanto Rozai Co., Ltd. and Osaka Permatite Co., Ltd. as general sales agents for the Kanto and Kansai regions respectively, and in 1969 it absorbed both companies and established a Kanto branch, a Hokkaido sales office, a Kansai branch, a Nagoya sales office and an Okayama sales office. Further offices and plants followed, including an Oita sales office and the Chiba Plant in 1970, a Kitakyushu sales office and the establishment of Nittoku Furnace Co., Ltd. in 1973, and the Yahama Plant in 1974. Over the following decades the company invested in automated production. It installed a fully automated Permacast production plant at the Chiba Plant in 1970 and a computer-controlled fully automated Permacast plant at the Okayama Plant in 1987. It added precast manufacturing equipment at Chiba in 1982 and expanded precast capacity at Yahama in 1992, the same year it installed a fully automated thermal spray material plant at Okayama. In the 2000s and 2010s it continued to modernize: a new technical research laboratory was built in 2003, a packaging materials warehouse and thermal spray materials laboratory were added at Okayama in 2006, and new castable and mortar plants (designated 3CP and 3MP) were installed at Okayama in 2010 and 2011. A fifth Okayama plant was acquired in 2012, and in 2013 new plants capable of producing castables and mortars (5CP) were installed at both the Okayama and Chiba plants. In 2015 the Yahama Plant installed solar power generation equipment and both Yahama and Chiba added factory buildings; in 2016 Yahama added a drying furnace and Chiba added a latest-generation castable plant (6CP) and drying furnace; and in 2018 Yahama added another factory building and drying furnace. The company remains privately held and is not listed on a stock exchange. It continues to operate as a specialist refractory materials manufacturer serving Japanese industry, with manufacturing concentrated at its Okayama, Chiba and Yahama plants and sales offices across Japan.
History
The history of Nihon Tokushu Rozai is rooted in the development of Japan's refractory industry. According to the company's own history, full-scale research into and manufacture of refractories in Japan began around the end of the Edo period, when the shogunate and domains built reverberatory furnaces for cannon casting amid debates over coastal defense. Refractories were then defined by three conditions: they must not melt even under intense heat, must withstand heat without cracking, and must be extremely precise and robust. The Okayama region became a center of refractory brick production because it had deposits of pyrophyllite (the raw material for refractory bricks), good access to fuel and shipping, and an existing ceramics tradition such as Bizen ware. Against this background, Kato Hisashi, the third son of Kato Ninkuro, who is regarded as one of the founders of the Okayama refractory industry, established the Kato Acid-Resistant Refractory Materials Research Institute in 1924 in what was then Uno Town, Kojima District (present-day Tamano City, Okayama Prefecture). This is the starting point of the company's history. The institute developed "Permatite," described as Japan's first air-setting mortar for refractory bonding, and subsequently developed and manufactured acid-resistant mortar "Asipulfite" and other products, selling them through Endo Goshi Kaisha as sales agent. In 1931 the business merged with Uno Refractory Brick Co., Ltd. and continued manufacturing these products as that company's special products section. In 1944 the special products section of Uno Refractory Brick Co., Ltd. merged with Endo Goshi Kaisha to establish Nihon Tokushu Rozai Co., Ltd. After the war the company broadened its product range. In 1954 it began manufacturing and selling the castable refractory "Permacast," and in 1960 it began manufacturing and selling the plastic refractory "Permaplast." In 1959 it concluded general sales agency agreements for the Kanto and Kansai regions with Kanto Rozai Co., Ltd. and Osaka Permatite Co., Ltd. respectively, entrusting them with sales of Nihon Tokushu Rozai products. In 1969 it absorbed and merged both companies and established a Kanto branch, a Hokkaido sales office, a Kansai branch, a Nagoya sales office and an Okayama sales office. Expansion continued in the 1970s. In 1970 the company set up an Oita sales office and opened the Chiba Plant, installing a fully automated Permacast production plant there and starting production. In 1973 it set up a Kitakyushu sales office and established Nittoku Furnace Co., Ltd. In 1974 it opened the Yahama Plant and installed precast manufacturing equipment there. In 1976 it expanded and renovated the wet products manufacturing plant at the Okayama Plant. In the 1980s and 1990s the company continued to invest in production technology. In 1982 it installed precast manufacturing equipment at the Chiba Plant. In 1987 it installed a computer-controlled fully automated Permacast production plant at the Okayama Plant. In 1992 it expanded the precast manufacturing plant at the Yahama Plant and improved assembly, packing and shipping facilities, and installed a fully automated thermal spray material production plant at the Okayama Plant. In the 2000s and 2010s the company modernized further. It built a new technical research laboratory in 2003. In 2006 it built a packaging materials warehouse and a thermal spray materials laboratory at the Okayama Plant. In 2009, marking the 40th anniversary of the 1969 merger and the 65th anniversary of its founding, it published a company history titled "Sixty-Five Years of Progress," and added a thermal spray material production plant at the Okayama Plant. In 2010 it installed a state-of-the-art castable production plant (3CP) at the Okayama Plant, and in 2011 a state-of-the-art mortar production plant (3MP) there. In 2012 it acquired a fifth plant as part of the Okayama Plant expansion. In 2013 it installed state-of-the-art production plants (5CP) capable of producing castables and mortars at both the Okayama and Chiba plants. In 2015 it installed solar power generation equipment at the Yahama Plant and added factory buildings at the Yahama and Chiba plants. In 2016 it installed a drying furnace at the Yahama Plant and a state-of-the-art castable production plant (6CP) and drying furnace at the Chiba Plant. In 2018 it added a factory building and drying furnace at the Yahama Plant. The company remains a privately held specialist manufacturer of monolithic refractories, headquartered in Tamano, Okayama Prefecture, with production at the Okayama, Chiba and Yahama plants and sales offices across Japan.
- 2016
Installed a drying furnace at the Yahama Plant and a state-of-the-art castable production plant (6CP) and drying furnace at the Chiba Plant.
- 2015
Installed solar power generation equipment at the Yahama Plant; added factory buildings at Yahama and Chiba plants.
- 2013
Installed state-of-the-art production plants (5CP) capable of producing castables and mortars at both the Okayama and Chiba plants.
- 2012
Acquired a fifth plant as part of the Okayama Plant expansion.
- 2011
Installed a state-of-the-art mortar production plant (3MP) at the Okayama Plant.
- 2010
Installed a state-of-the-art castable production plant (3CP) at the Okayama Plant.
- 2009
Published company history "Sixty-Five Years of Progress" and added a thermal spray material production plant at the Okayama Plant.
- 2006
Built a packaging materials warehouse and thermal spray materials laboratory at the Okayama Plant.
- 2003
Built a new technical research laboratory.
- 1992
Expanded precast manufacturing plant at Yahama Plant and installed a fully automated thermal spray material production plant at the Okayama Plant.
Products and positioning
Specialist manufacturer of monolithic (unshaped) refractories, combining long experience with new technology to supply superior products and peripheral technologies for high-temperature industrial furnaces.
Permacast
Castable refractory first manufactured and sold in 1954; produced at automated plants including the Chiba Plant (1970) and Okayama Plant (1987).
Permaplast
Plastic refractory first manufactured and sold in 1960.
Permatite
Described as Japan's first air-setting mortar for refractory bonding, developed from 1924.
Asipulfite
Acid-resistant mortar developed and manufactured after Permatite.
Precast blocks
Design, manufacture and sale of precast shaped castable refractory blocks; precast equipment installed at Yahama (1974, 1992) and Chiba (1982).
Thermal spray materials
Produced at a fully automated plant installed at the Okayama Plant in 1992, with additional capacity in 2009.
Sources5 sources
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