Method and apparatus for producing panels

Abstract

Remoldable panels of a high melting point, high tenacity thermoplastic polymer and a thermosensitive organic filler are produced by forming a mixture of polymer and filler, extruding the mixture to form a web and calendaring the web prior to its solidification. The mixture is formed and extruded in a single step by separately feeding the polymer and the thermosensitive filler into an integral mixing and extruding space that has a feed end and an extrusion end and includes a pair of co-rotating parallel elongated elements. Each of the co-rotating parallel elements has a length extending between the feed end and the extrusion end of the integral space. At least three helical extrusion sections are distanced along the length of the elements and at least two kneading sections are included. The kneading sections and the extrusion sections of the elements are provided at positions along their length to form kneading zones and extrusion zones so as to provide one kneading zone between adjacent extrusion zones in the integral space. The polymer is introduced into the integral space in a first extrusion zone near the feeding end while the thermosensitive filler is introduced in a second extrusion zone closer to the extrusion end than the first extrusion zone. A venting means is connected to the extrusion zone nearest the extrusion end.