| 摘要 |
Acid resistant containers, such as battery boxes, are made from a mouldable composition comprising hydrolysed vegetable fibrous material free from acid-soluble material and containing 65-57 per cent cellulose and 35-43 per cent lignin impregnated with a single-stage thermosetting phenol-formaldehyde resin or cresol-formaldehyde resin, or a combination of both, in quantities of 15-45 per cent of the total composition. The vegetable fibrous material, i.e. hardwood sawdust, such as red oak, maple, or gum sawdust, is bleached with dilute sulphuric acid, either in a steam-heated chamber or in a steam-jacketed tube until pure ligno-cellulose remains. The hydrolysed product is filtered off, washed and ground either wet or dry, the material being dried in either case to a moisture content of 4-15 per cent, and an aqueous solution of the synthetic resin added, the water-wood fibre ratio being 0.5 : 1-2.5 : 1. An accelerator, such as hexamethylenetetramine, ammonium hydroxide or calcium oxide, and a mould lubricant, such as 2-50 per cent fatty acids or their salts, may be added and the mix passed through a rubber mill to complete the impregnation of the fibres. The sheeted material is granulated and dried to a moisture content of 4-5 per cent by weight. |
