Patent GB-1028844-A (GB)
Title: Improvements relating to cellular insulating material
Inventor: HERON GORDON FREDERICK
IPC: C04B30/02
Filed: 1963-02-21
Abstract: A cellular material is produced by (a) forming a stable dispersion of film-forming asbestos fibres, with or without other fibres, in water with the use of a precipitable surface-active agent or agents (A); (b) adding an agent (B) to coagulate the dispersion and precipitate agent (A) as a binder for the fibres, while continuously disintegrating the films formed; (c) introducing the resultant mixture into a mould; and (d) heating it in the mould to remove water and leave a dry cellular structure. The term "film-forming" means that if a dispersion of fibres is spread over a flat surface and the water is evaporated, the fibres will form a film which may be removed from the surface.  The preferred fibres are chrysotile asbestos. Other fibres which may be included may be organic or inorganic, e.g. chopped glass strands, amphibole asbestos or undispersed chrysotile asbestos. Agent (A) may be a water-soluble soap or another type, e.g. sodium dodecyl benzene sulphonate, or a mixture thereof.  Agent (B) may be a soluble salt of a polyvalent metal, e.g. lead nitrate, copper sulphate, thorium nitrate or aluminium sulphate.  Additional binders may be present, e.g. artificial resins, or ethyl silicate plus sodium hydroxide.  Other additives which may be used include colloidal silica, boron, graphite, polymer foam expanding agents, and foamable polystyrene beads.  After step (c) above, some of the water may be allowed to drain off through drainage holes in the mould.  The undrained water may be removed by heating the mould to 200-300 DEG C.; vapour may escape through perforated top plates. The product may then be baked for a further period at 200-300 DEG  C. A continuous slab may be formed by use of a channel-shaped mould formed by an endless band which travels through heating chambers. The product may be used as a lightweight thermal or acoustic insulation material.ALSO:A cellular material is produced by (a) forming a stable dispersion of film-forming asbestos fibres, with or without other fibres, in water with the use of precipitable surface-active agent or agents (A); (b) adding an agent (B) to coagulate the dispersion and precipitate agent (A) as a binder for the fibres, while continuously disintegrating the films formed; (c) introducing the resultant mixture into a mould; and (d) heating it in the mould to remove water and leave a dry cellular structure.  The term "film-forming" means that if a dispersion of fibres is spread over a flat surface and the water is evaporated, the fibres will form a film which may be removed from the surface.  The preferred fibres are chrysotile asbestos. Other fibres which may be included may be organic or inorganic, e.g. chopped glass strands, amphibole asbestos or undispersed chrysotile asbestos.  Agent (A) may be a water-soluble soap or another type e.g. sodium dodecyl benzene sulphonate, or a mixture thereof.  Agent (B) may be a soluble salt of a polyvalent metal, e.g. lead nitrate, copper sulphate, thorium nitrate or aluminium sulphate.  Additional binders may be present, e.g. artificial resins, or ethyl silicate plus sodium hydroxide.  Other additives which may be used include colloidal silica, boron, graphite, polymer foam expanding agents, and foamable polystyrene beads.  After step (c) above, some of the water may be allowed to drain off through drainage holes in the mould.  The undrained water may be removed by heating the mould to 200-300 DEG C.; vapour may escape through perforated top plates.  The product may then be baked for a further period at 200-300 DEG C.  A continuous slab may be formed by use of a channel-shaped mould formed by an endless band which travels through heating chambers.  The product may be used as a lightweight thermal or acoustic insulation material.