Patent GB-1444561-A (GB)
Title: Continuous production of elongate section members
IPC: B29C48/34
Filed: 1973-09-21
Abstract: 1444561 Co-extruding materials at differing temperatures DYNAMIT NOBEL AG 21 Sept 1973 [22 Sept 1972] 44503/73 Heading B5A [Also in Division E1] An extruded section, e.g. for use as a window frame member, comprises a rigid polyvinyl chloride which may be foamed, solid or tubular section having a simultaneously extruded exterior coating extending around all its periphery, or as one or two longitudinally extending stripes. The coating is simultaneously extruded at a different temperature from a die located at the outlet of, and thermally insulated from, the die from which the section is extruded, and preferably comprises a homo- or co-polymer of methyl methacrylate of molecular weight of 120,000 to 180,000. The extruded section passes through a sizing die downstream of the extrusion die 3, and may comprise the configuration defined by the extrusion die outlet 2 of Fig. 2a, having a plurality of bores each defined by a die mandrel, such as 12 or 12a, and with the coating along only one side and which is discharged from a die outlet 7 located upstream of the end face of the remainder of the outlet 2. The outlets 2 and 7 are defined in die members 3, 6 supplied from separate extrusion sources, with the thermal insulation comprising thermally insulating material, or an air gap as shown. In the Figs. 3 and 3a embodiment (not shown), the Fig. 2a extruded section is provided with a further coating of the same material on its lower, and lower side surfaces, by a further outlet (7a) of the member 6 which is supplied with the coating material by an annular die passage (24) interconnecting the passages (7), (7a). In the Fig. 4 embodiment (not shown) a square section tubular member is extruded with a coating of a different material on each of three sides, two of the coatings extending completely across adjacent sides, and a third coating comprising a strip extending partially across another side intermediate the edges thereof. In the Figs. 1-4 embodiment, the section and coating are discharged from an outlet in a single plane but the exterior periphery of the part of the outlet defining the coating may extend downstream of the remainder of the outlet, as in the Fig. 5 embodiment (not shown). Such an outlet is shown in the Fig. 6 modification of the Fig. 2a embodiment in which the mandrel 12a is also so extended and provided with a taper 27. In the Figs. 7 and 7a embodiment (not shown) a square tubular section is provided around all its periphery with a coating discharged from a single coating outlet. In the Fig. 8 embodiment, a square tubular section is coated across one side by a coating discharged from an outlet 7, and the thickness of the coating may be varied by varying the thickness of the outlet 7 by means of replaceable plates 17. In the Fig. 9 embodiment, the coating thickness is varied by a vertically adjustable die part 11. In the Fig. 10 embodiment (not shown), a square tubular section is provided along one side with a pair of coating strips of the same material, each extending from one edge of the side and the coatings being discharged from outlets supplied from a single extrusion source.