| 摘要 |
PURPOSE:To improve the quality of pencil lead, by using an oily substance integrated with a pore-forming material as a thickener, thereby increasing the viscosity of the oily substance. CONSTITUTION:A pencil lead is produced by heat-treating a thin rod at a high temperature and impregnating an oily substance into obtained baked core material having interconnected pores. In the above process, a thickener consisting of the above oily substance (e.g. spindle oil) integrated with a pore-forming material (e.g. naphthalene and polystyrene) is used to obtain the objective pencil lead. The amount of the thickener is preferably 5-30wt.% based on binder.
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