Schreibstift, Schreibmine und Verfahren zur Herstellung von Schreibstiften

摘要

In a pencil consisting of a solid lead and of a lead casing, the binder used at least in the casing material is Polystyrol. In addition, the casing material contains talcum-filled LDPE, thus improving the sharpenability of the casing material and its adherence to the lead material. It is also proposed to use talcum-filled Polystyrol. The proportion of Polystyrol lies from 60 to 70 % by weight, of the talcum-filled LDPEs from 20 to 40 % by weight. Standard Polystyrol or HIPS Is also used for the lead material. Both the casing material and the lead material are extruded, an endothermally acting blowing agent being added to the Polystyrol only when the latter is already in the extruder.