| 摘要 |
<p>PURPOSE:To obtain a thermoplastic resin foam in multi-layer structure consisting of a plurality of layers whose packings of foaming fine stripes are different from each other and outward foam magnifications are different from each other, by a method wherein a cap having a large number of extrusion holes whose arrangement intervals are different from those of the adjoining group is used and a relation between an extrusion rate and take-off rate is controlled so as to fall within a specific range. CONSTITUTION:Thermoplasitc resin kneaded with a foaming agent within an extrusion machine 1 is extruded and foamed through a cap 5, introduced into a shaping device 6 and taken off by a take-off machine 7. Extrusion holes 51, whose diameter is Dmm, consisting of a plurality of groups whose arrangement intervals are different from each other are bored on the cap 5. The intervals L of the extrusion holes 51 are given by an expression of 0.9 DR<1/2=L<=3.6DR<1/2> and R falls within a range of a free foam magnification of a foam fine stripe. As for the foam fine stripe 8, a take-off rate of the same is controlled and taken off at the rate V falling within a range of 0.54VD{R<1/2>/(SIGMALi/n)}<=V<=1.26VDR<1/2>/SIGMALi/n (V<V is given and V is the extrusion rate of the foam fine stripe, (n) is the number of the groups of the extrusion holes, Li is the interval of the extrusion holes of the (i)th group of the extru sion holes).</p> |
