| 摘要 |
PROBLEM TO BE SOLVED: To prepare a foamed thermoplastic resin sheet which enables an attempted secondary thickness to be secured even at a low level of a residual blowing agent, has a long web life, and gives a molded article with high strengths and to provide a process for producing the same. SOLUTION: This foamed sheet is produced by extrusion foaming a melt- foamable thermoplastic resin with an extruder. In the cross section of the foamed sheet in the thickness direction at right angle to the direction of extrusion, the main part 10, which is a part remaining when the front and back surface layers each in a thickess of 0.1 mm are excluded, satisfies the relation: 3.1<=n<=4.5 [wherein n=(L1/L2)+0.74.α-0.0043.β; L1 (μm) is the average cell size in the width direction at right angle to the direction of extrusion; L2 (μm) is the average cell size in the thickness direction;α(mm) is the average thickness of the total foamed sheet; andβ(g/m<2> ) is the basis wt. of the sheet].
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