| 摘要 |
PURPOSE:To obtain the titled foam which has uniform, fine cells and excellent appearance and heat resistance and is highly expanded, by extrusion-expanding a compsn. consisting of a PP resin, a main chain breakage inhibitor, a blowing agent and a peroxide under specified conditions. CONSTITUTION:A material 2 obtd. by pre-blending 100pts.wt. PP resin (A) having an MFI of 0.5-10 with 0.02-2.0pts.wt. main chain breakage inhibitor (B) (e.g., p,p'-dibenzoylquinone dioxime), etc. is fed through a hopper 1 to an extruder 3, wherein the temp. of a die 5 is set at about 150 deg.C to melt it. 0.05-2.0pts.wt. peroxide (D) having a one-min half-life temp. higher than the m.p. of the compo nent A [e.g., 2,5-dimethyl-2,5-di(t-butylperoxide)hexane], diluted with a volatile blowing agent (C) (e.g., butane) is fed through pressure inlets 4 and 6 to the extruder under pressure. The component d is used in an amount of 0.1-2.0 times that of the component B. While the mixture is reacted and the gel fraction is kept at 0%, it is thoroughly kneaded and extruded through the die 5 to obtain the titled foam having an expansion ratio of 1.5-60. |
