PURPOSE: To obtain predetermined compressive strength and tensile strength by a method wherein a reinforcing plate of a thermoplastic resin has a hollow inside, while a plurality of recesses are formed on two opposite faces on the reinforcing plate so that their bottoms are opposite to each other.
CONSTITUTION: A corrugated board box 11 is equipped with a reinforcing plate 1 inside sides 10a, 10a which are opposite to each other in a corrugated board box body 10. The reinforcing plate 1 comprises a flat plate-like body having a hollow 9 inside by blow-molding a thermoplastic resin. Then on a surface 2 and a rear face which are opposite to each other, a plurality of recesses 4 regularly arranged are formed. The recesses 4 are formed into an approximate truncated cone shape which gradually tapers from its opening face toward a bottom 4a. Thus predetermined compressive strength and tensile strength can be further improved.
NAKAMURA YUKITO
KIKUCHI TOSHITSUGU
OMURA YOSHINORI
YABE TORU
