| 摘要 |
PROBLEM TO BE SOLVED: To provide an extrusion foamed sheet which has preferable thermoformability and cushioning properties, has satisfactory retention property and rigidity (anti-deflection) and is excellent in shock resistance at a low temperature in relation to a foamed sheet having a high expansion ratio, made of a resin comprising primarily high-density polyethylene based resin. SOLUTION: The polyethylene-based resin extrusion foamed sheet has apparent density of 0.02 to 0.1 g/cm<SP>3</SP>, a sheet thickness of 1 to 10 mm, a crystallization temperature of 110 to 120°C and a percentage of closed cells of 30% or more, wherein the following requirements (α), (β), (γ) are satisfied: (α) the melt tension at crystallization temperature +15°C of the foamed sheet is 20 cN or more; (β) the melting heat quantity of the foamed sheet by the thermal flux differential scanning calorimetric measurement is 145 to 175 J/g; (γ) the time until reaching the heat quantity of 80% of the total crystallization heat quantity from the starting of crystallization to the completion of crystallization when heating the foamed sheet from 23°C to 200°C at a temperature rising rate of 10°C/min with the thermal flux differential scanning calorimetric measurement and, thereafter, cooling the foamed sheet from 200°C to 30°C at a temperature falling rate of 10°C/min is 90 to 200 s. COPYRIGHT: (C)2011,JPO&INPIT |
