| 摘要 |
PURPOSE:To prepare a pencil lead with improved strength, color depth and writing property, by forming a kneaded mixture of a colorant and a specified binder into pencil lead shape, followed by hardening and burning in a non-oxidizing atmosphere. CONSTITUTION:A binder consisting of 100pts.wt. bismaleimide-triazine resin and 50-100pts.wt. thermoplastic resin (e.g., PVC having a degree of polymerization of 500-1,000) and a colorant such as graphite or carbon black are kneaded at 100-120 deg.C and the mixture is formed into pencil lead shape having a diameter of 0.3-1.0mm. by means of an extruder kept at 100-120 deg.C. The formed lead is heated at 180-200 deg.C for 1-2hr in the air for hardening and is burned at above 1,000 deg.C in a non-oxidizing atmosphere, followed by impregnation with an oil. |
