To manufacture three-layer structural fiber boards being lightweight and having voids, smoothness, and water resistivity by the use of non- decomposable waste paper intended to be scrapped in its middle layer, and also using pelletized fiber board material as a mat.
In use of waste paper, pellets 4 having appropriate shapes, apparent gravity, compression strength, and so on are disposed in the middle layer 2 of a three-layer structure for voids needed in terms of a gravity of products. A prerequisite for achieving lightweight, high bending strength, and bending elasticity is to form a high-compression-strength middle layer 2 with respect to rigid front and rear layers 1, 3 by effectively granulating and utilizing material being as light and small as possible. In particular, pellets made of waste paper consisting mainly of pulp fiber and synthetic resin binder are filled in the middle layer 2, thereby forming a three-layer structural composite fiber board by the agency of melt-fixture of the synthetic binder.
ONOZUKA KATSUMI
SAKAZUME HISATO
