| 摘要 |
PURPOSE:To easily produce a bulky foamed body with a high apparent expansion ratio, by staggering and bending strings of a specified thermoplastic resin containing a foaming agent in a forming device to firmly weld the strings to each other. CONSTITUTION:A mixture of 100pts.wt. of an ethylene resin and 10-80pts.wt. of a polybutene resin is used as a thermoplastic resin containing a foaming agent. The mixture is extruded through a multiplicity of extrusion holes of a mouthpiece fitted to the tip of an extruder, and while taking off the resultant foamed thin strings at a rate lower than the extruding rate, the strings are bent and staggered in the forming device to weld the contact parts of the strings to each other. In this case, the hole spacing L of the mouthpiece 5 is preferably so set that 0.9D R<=L<=3.6D R, where R is the free expansion ratio of foamed strings in the case of free extrusion through the extruding holes of the mouthpiece, in order that the cross-sectional shape of the mouthpiece 5 is similar to and smaller than that of the foamed body 8. The foamed thin strings are taken off as a foamed body 8 having the same shape as the inside shape of the forming device 6, by controlling the extruding rate or the take-off rate so that the take-off rate (v) (<V) is made in the range of 0.54VD(R/L)<=v<=1.26VD(R/L). |
