Expanded pencil and method for manufacturing same

摘要

The pencil (1) comprises a refill part (3) including a lead (4), and an envelope portion (2) that surrounds the refill part and is made of an expanded synthetic material. The refill part is partially expanded. The refill part includes an intermediate layer (5) surrounding the lead. The intermediate layer is made of a material containing an expanded synthetic polymer. The lead is nonexpanded or expanded. The envelope portion and the intermediate layer comprise expanded thermoplastic materials. The expanded parts result from a thermal expansion action of a blowing agent. The pencil (1) comprises a refill part (3) including a lead (4), and an envelope portion (2) that surrounds the refill part and is made of an expanded synthetic material. The refill part is partially expanded. The refill part includes an intermediate layer (5) surrounding the lead. The intermediate layer is made of a material containing an expanded synthetic polymer. The lead is nonexpanded or expanded. The envelope portion and the intermediate layer comprise expanded thermoplastic materials. The expanded parts result from a thermal expansion action of a blowing agent. The blowing agent is physical blowing agents and heat-expandable microspheres. The blowing agent is introduced into the material of the envelope portion in a proportion of 0.5-3 wt.% compared to the total weight of the envelope portion and introduced into the material of the refill part in a proportion of 0.1-1 wt.% compared to the total weight of the refill part. The blowing agent includes the microspheres whose size is 20-40 micro m in an expanded state. The lead is hard or soft. An independent claim is included for a method for manufacturing a pencil.