| 摘要 |
A process for obtaining a mouldable material comprises bringing together a cellulosic material and a multi-component catalyst system comprising two or more components which react to form a catalyst system capable of initiating the polymerization of aliphatic 1-olefines, the cellulosic material being brought into contact with the components of the catalyst system before the components have reacted substantially with each other, and, before or after the complete formation of the catalyst system, introducing an aliphatic 1-olefine containing less than 6 carbon atoms and polymerizing the 1-olefine to form a polymer on the cellulosic material. Specified olefines are ethylene, propylene, 1-butene, 1-3-butadiene and isoprene. The cellulosic material may be wood, wood fibres, sawdust, wood flour, paper pulp, bagasse, cotton in the form of batting or linters, hemp, regenerated cellulose produced from viscose or from cuprammonium solutions of cellulose, and compounds such as cellulose acetate, the material being in the form of particles, fibres or filaments. The catalyst may comprise one or more alkyl or aryl compounds of lithium, sodium, potassium, magnesium, calcium, zinc, cadmium, boron or aluminium and at least one halide or ester of titanium, zirconium, vanadium or chromium. The polymerization must as usual be carried out in the substantial absence of oxygen or water and may be carried out under atmospheric pressure at 20 DEG -100 DEG C. The proportion of polymer formed on the cellulose may be from about one up to over 100% of the weight of the cellulose, and is preferably 5 to 75% by weight of the product. The product is hydrophobic, but this property may be changed by the addition of a fraction of one per cent of a wetting agent after polymerization and prior to or after moulding the material to form, for example, a storage battery separator. The material may be moulded without substantial pressure to form a self-supporting porous article readily permitting the passage of gases and liquids and having heat and sound insulating properties. When the moulded article is required to have a maximum tensile strength, the material is preferably moulded at a temperature at or slightly above the crystalline melting point of the polymer coating the cellulose particles or fibres. The porosity of pressure-moulded articles may be increased by dissolving out all or part of the cellulose with liquids such as concentrated sulphuric acid, concentrated aqueous caustic soda solution or carbon disulphide either before or after moulding. High-density sheets and other articles impervious to liquids may be formed by moulding the material at the fusing temperature of the polymer component and pressures of 2,000 to 10,000 p.s.i. The moulding powder may be softened by mixing it with a solvent for the polyolefine and the softened mass formed into an article with accompanying evaporation of the solvent. In an example, 24 grams of wood cellulose floc dispersed in 1400 ml. of dry toluene is reacted at room temperature in an atmosphere of nitrogen with 0,0316 mol. of titanium tetrachloride and 0,0712 mol. of methyl-magnesium bromide added. A stream of gaseous ethylene is passed into the mixture of 50 DEG to 60 DEG C. until about 24 grams of the gas has been absorbed. The solution is cooled, diluted with methanol, filtered and the filter cake washed with methanol and dried to form a white, powdery cellulose-polyethylene material. The powder is formed into a web on a paper making machine and lightly compressed at about 150 DEG C. to form a porous self-supporting sheet which is cut into storage battery separators, a wetting agent having been added to the powder before moulding or to the sheet after moulding.ALSO:A process for obtaining a mouldable material comprises bringing together a cellulosic material and a multi-component catalyst system comprising two or more components which react to form a catalyst system capable of initiating the polymerisation of aliphatic 1-olefines, the cellulosic material being brought into contact with the components of the catalyst system before the components have reacted substantially with each other, and, before or after the complete formation of the catalyst system, introducing an aliphatic 1-olefine containing less than 6 carbon atoms and polymerising the 1-olefine to form a polymer on the cellulosic material. Specified olefines are ethylene, propylene, 1- butene, 1-3- butadiene and isoprene. The cellulosic material may be wood, wood fibres, sawdust, wood flour, paper pulp, bagasse, cotton in the form of batting or linters hemp, regenerated cellulose produced from viscose or from cuprammonium solutions of cellulose, and compounds such as cellulose acetate, the material being in the form of particles, fibres or filaments. The catalyst may comprise one or more alkyl or aryl compounds of lithium, sodium, potassium, magnesium, calcium, zinc, cadmium, boron or aluminium and at least one halide or ester of titanium, zirconium, vanadium or chromium. The polymerization must as usual be carried out in the substantial absence of oxygen or water and may be carried out under atmospheric pressure at 20-100 DEG C. The proportion of polymer formed on the cellulose may be from about one up to over 100% of the weight of the cellulose, and is preferably 5 to 75% by weight of the product. The product is hydrophobic but this property may be changed by the addition of a fraction of 1% of a wetting agent after polymerization and prior to or after moulding the material to form, for example, a storage battery separator. The material may be moulded without substantial pressure to form a self-supporting porous article readily permitting the passage of gases and liquids and having heat and sound insulating properties. When the moulded article is required to have a maximum tensile strength, the material is preferably moulded at a temperature at or slightly above the crystalline melting point of the polymer coating the cellulose particles or fibres. The porosity of pressure moulded articles may be increased by dissolving out all or part of the cellulose with liquids such as concentrated sulphuric acid, concentrated aqueous caustic soda solution or carbon disulphide either before or after moulding. High density sheets and other articles impervious to liquids may be formed by moulding the material at the fusing temperature of the polymer component and pressures of 2000 to 10,000 p.s.i. The moulding powder may be softened by mixing it with a solvent for the polyolefine and the softened mass formed into an article with accompanying evaporation of the solvent. In an example, 24 grams of wood cellulose floc dispersed in 1400 ml of dry toluene is reacted at room temperature in an atmosphere of nitrogen with 0,0316 mol of titanium tetrachloride and 0,0712 mol of methyl-magnesium bromide added. A stream of gaseous ethylene is passed into the mixture at 50 to 60 DEG C. until about 24 grams of the gas has been absorbed. The solution is cooled, diluted with methanol, filtered and the filter cake washed with methanol and dried to form a white, powdery cellulose-polyethylene material. The powder is formed into a web on a paper making machine and lightly compressed at about 150 DEG C. to form a porous self-supporting sheet which is cut into storage battery separators, a wetting agent having been added to the powder before moulding or to the sheet after moulding. |
