| 摘要 |
PROBLEM TO BE SOLVED: To provide multi-layered cardboard excellent in buffering property and slip-prevention while exhibiting a high compression strength, burst strength and interlayer strength. SOLUTION: This multi-layered cardboard 1 obtained by using a natural fiber as a main raw material and equipped with at least a surface layer 3, an intermediate layer 2 containing thermally foamed particles and a reverse surface layer 4 is characterized by including projected parts 5 at the outer surfaces of the surface layer 3 and reverse surface layer 4 by the presence of aggregated lumps of the thermally foamed particles in the intermediate layer 2, having≥40 and≤100μm mean height of the projected parts 5 and forming the aggregated lumps of the thermally foamed particles by adding a cationic coagulant and a cationic flocculant in this order to the thermally foamed particles dispersed in an aqueous solution in advance. It is preferable that the unit weight of the surface layer is≥25 and≤80 g/m<SP>2</SP>and the unit weight of the intermediate layer is≥25 and≤80 g/m<SP>2</SP>. Also, the natural fiber at the intermediate layer preferably contains≥70 mass% broadleaf tree kraft pulp. COPYRIGHT: (C)2011,JPO&INPIT |
