Rock wool

Japanese: 岩綿 - がんめん（英語表記）rock wool

A type of man-made inorganic fiber used as a building material. Also called rock wool. It is made by mixing lime with a mixture of rocks such as andesite and basalt, and slag of manganese and nickel, melting them at high temperatures of 1500-1600°C, letting them flow out from the bottom of a furnace, and blowing them away with centrifugal force, compressed air, or high-pressure steam to create fibers. Because it is molten and vitreous, the fibers are brittle and cannot be made into long fibers. It is 2-20 micrometers thick and about 10-100 millimeters long.

The product often contains small particles that do not form fibers but remain in the molten state, and products containing large amounts of these are defective. It is generally lightly pressed into plates and used as a heat retaining material (insulating material) and sound absorbing material. Also, because it is inorganic, it is mixed with asbestos and cement and sprayed, and is used as a fireproof material.

[Minoru Mori]

Product Type

(1) Rock wool insulation material: Rock wool molded into a plate shape using an appropriate adhesive. Density: 0.2 grams/cubic centimeter, thermal conductivity: 0.044 kilocalories/meter/hour/℃ or less.

(2) Rock wool sound absorbing material: Made into a plate shape using an appropriate adhesive. There are blanket-shaped ones made by reinforcing the plate shape with flat lath, and ones made by cutting layered rock wool to a certain width, lining it up vertically, and finishing it by covering one side with cloth.

(3) Rock wool felt: Rock wool is made into a resilient felt-like material by applying an appropriate adhesive.

(4) Rock wool insulation tubes: Rock wool is formed into a cylindrical shape using a suitable adhesive, and if necessary, a suitable outer covering is attached or a waterproofing agent is added to make the cylindrical shape.

[Minoru Mori]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

人工無機繊維の一種で、建築材料として用いられる。ロックウールともいう。安山岩、玄武岩などの岩石や、マンガン、ニッケルなどの鉱滓(こうさい)（スラグslag）などの混合物に石灰を混合して1500～1600℃の高温で溶融して炉の下から流出させ、これを遠心力、圧縮空気または高圧蒸気で吹き飛ばして繊維状にしたもの。溶融してガラス質を呈しているため繊維はもろく長繊維はできない。太さは2～20マイクロメートルで、長さが10～100ミリメートル程度である。

　製品には一部繊維にならずに溶融粒のままの状態の小粒が混じることが多く、これが多量に含まれているものは不良品である。一般には軽くプレスして板状にし、保温材（断熱材）、吸音材として用いる。また無機質であるため、石綿(せきめん)、セメントと混合吹付けし、耐火材としても用いる。

［森　実］