| 摘要 |
PURPOSE:To safely and simply obtain a polyolefin foam having fine, uniform and closed empty pores, by impregnating a polyolefin resin with a blowing agent containing a specific liquefied hydrocarbon, adding a blowing auxiliary such as an organic acid or an inorganic acid during extrusion molding of the resin. CONSTITUTION:A polyolefin resin (e.g. low-density polyethylene) is previously impregnated with <=1wt.% of a blowing agent containing >=80% of a 3-4C liquefied hydrocarbon (e.g. liquefied propane) in a pressure container, mixed with a blowing auxiliary comprising an organic acid (e.g. citric acid) or an inorganic acid (e.g. sodium hydrogencarbonate) or both, uniformly blended by a blender, supplied to a hopper of an extrusion molding machine equipped with a die, continuously extruded and molded to give the objective polyolefin foam without danger of explosion and problems in terms of food sanitary, having uniform and closed empty pores, useful as a tray for food, medicine, medical use and an agricultural material for raising seedling. |
