Cylindrical composite paperboard cushion core and process for producing same.

摘要

A cylindrical composite paperboard cushion core for winding a sheet material therearound without forming undesirable stepwise marks thereon, comprises a cylindrical paperboard substrate (2) and a cushion layer (3) formed on the cylindrical paperboard substrate from an expanded paper sheet having a density of 0.1 to 0.4 g/cm<3>, the expanded paper sheet being formed by forming an unexpended paper sheet containing therein a plurality of expansible microcapsules each having a volatile liquid core contained in a thermoplastic resin shell and capable of starting an expansion at a temperature of 80 DEG C to 200 DEG C, and heating the unexpanded paper sheet at the expansion-starting temperature of the microcapsules or higher, to cause the paper sheet to be expanded.