| 摘要 |
<p>1486870 Coated products ASAHI KASEI KOGYO KK 21 May 1975 [22 May 1974 (2) 8 July 1974 (2) 29 July 1974 30 Oct 1974 29 Nov 1974 (2)] 21961/75 Heading B2E [Also in Divisions B5 and C3] A coated product comprises a coating layer of a magnesia cement composition which comprises, on a dry weight basis 42-94% active magnesia (obtained by heating a decomposable magnesium compound at 400-1000‹C) 5-38% magnesium sulphate, and 1-20% cellulose pulp or cellulose pulp/glass fibre mixture. The composition is preferably obtained by mixing active magnesia, cellulose pulp (optionally together with glass fibre). and an aqueous solution comprising at least 10% by weight magnesium sulphate. The solution may also comprise magnesium chloride, such that the weight ratio of sulphate to chloride is 2-10:1. The weight ratio of cellulose pulp to glass fibre, if present. is preferably 0.1-10:1. Other fibres may be included e.g. asbestos, carbon, cotton or rayon. The cement composition may be coated on, e.g., cellular concrete board, plywood. gypsum plaster board, plastic foam (e.g. foamed phenolic resin) or cemented excelsior board, and hardened in situ thereon. The magnesia cement layer is preferably of thickness 0.2-6mm.</p> |
