Foamed thermoplastic resin sheet and manufacturing method of the same

摘要

A foamed thermoplastic resin sheet has a foaming ratio of not less than 2.5, and cells, existing in an interior part which extends inward from a depth of 20 percent a whole thickness of the sheet from the front and rear surfaces thereof respectively in a thickness direction thereof and from 15 percent a width of the sheet from both side edges respectively, satisfy the following expressions (1) and (2): $$ $ where\; C\; represents\; a\; mean\; cell\; diameter\; in\; the\; thickness\; direction\; of\; the\; foamed\; thermoplastic\; resin\; sheet,\; D\; represents\; a\; mean\; cell\; diameter\; in\; an\; extrusion\; direction\; (MD)\; of\; the\; same,\; and\; E\; represents\; a\; mean\; cell\; diameter\; in\; the\; width\; direction\; (TD)\; of\; the\; same.\; The\; foamed\; thermoplastic\; resin\; sheet\; thus\; arranged\; has\; a\; high\; foaming\; ratio,\; and\; is\; formed\; thick.\mathop{\mathrm{image}}$$$