| 摘要 |
PROBLEM TO BE SOLVED: To obtain a foamed sheet of a styrenic resin for thermoforming having excellent stability against deformation, safety for a human body and operability and useful as a food tray, etc., by using carbon dioxide as a foaming agent and a specific foam nucleating agent, introducing the foaming agent into the styrenic resin under pressure in a gas state and extruding the resin while foaming. SOLUTION: This foamed sheet of a styrenic resin for thermoforming includes only air in the cell of the resin, has <=30% volume swelling rate after being heated at a temperature 20 deg.C higher than the Vicat softening point for 3min, 0.5-2.5mm thickness and 200-500g/m<2> unit weight based on 1mm thickness and is obtained by using a nonionic inorganic fine powder (A) (e.g. a talc or a clay having <=20μm particle diameter) as a nucleating agent for foaming and introducing carbon dioxide (B), which is a foaming agent, into a styrenic resin melt in an extruder under pressure and extruding the styrenic resin containing the carbon dioxide to form the foamed sheet. The amount of the component B to be used is preferably 0.05-0.5mol based on 1kg total amount of the components A and C and the amount of the component A is 0.1-5wt.% based on that of the component C. |
