THERMOPLASTIC RESIN FOAM SHEET, METHOD FOR PRODUCING THIN SHEET OF THERMOPLASTIC RESIN FOAM, AND LIGHT-REFLECTING PLATE

摘要

Provided is a thermoplastic resin foam sheet in which first bubbles and second bubbles are included in the thermoplastic resin sheet, and the second bubbles have a greater average diameter than that of the first bubbles and are distributed in the thickness-wise middle part of the thermoplastic resin sheet. Further provided is a production method, in which, during formation of a resin sheet (13) by extrusion molding of a thermoplastic resin in which a plasticizer is dispersed, extrusion is performed so that a shear force is applied to the extruded resin sheet (13), and the resin sheet (13) is impregnated with an inert gas, after which the resin sheet (13) is heated and caused to foam; first bubbles (11) are formed on both thickness-wise sides, and second bubbles (12) having a greater average diameter than that of the first bubbles (11) are formed at the thickness-wise center to form a thermoplastic resin foam sheet (10); and the region of the thermoplastic resin foam sheet (10) in which the second bubbles (12) are formed is sliced by a slicing blade (20) to divide the thermoplastic resin foam sheet (10) in the plane intersecting the thickness direction to form thin sheets (14, 15) of the thermoplastic resin foam.