| 摘要 |
The present invention relates to a pencil for writing or colouring, which includes the following three layers produced by co-extrusion: a non-expanded polyolefin lead; with a non-expanded protective intermediate layer surrounding the lead and including a mixture of polystyrene and EVA; and an expanded synthetic wood material made of a styrene polymer surrounding the protective intermediate layer, the thickness ratio of the protective intermediate layer to the radius of the lead being from 0.05 to 0.17, preferably from 0.07 to 0.15. |
