Patent GB-1105983-A (GB)
Title: A method and apparatus for the preparation of a composite thermoplastic resinous article
IPC: B29C48/08
Filed: 1966-02-03
Abstract: 1,105,983. Conjugate films and filaments; extruding composite plastics articles. DOW CHEMICAL CO. 3 Feb., 1966 [9 Feb., 1965], No. 4861/66. Headings B5A and B5B. A method of preparing a composite thermoplastic resinous article comprises extruding a first stream of a synthetic thermoplastic rbsinous material in a heat plastified condition, the first stream of material on Cooling being capable of orientation to provide a high tensile strength mono-directionally oriented body, dividing the first stream into a plurality of substreams, providing at least a second stream of synthetic thermoplastic resinous material, which on cooling, has an elongation at break substantially greater than the elongation at break of the oriented thermoplastic resinous material, causing the plurality of substreams within the second stream of thermoplastic resinous material to form a composite stream having a plurality of spaced-apart sub-streams encapsulated by a matrix formed by the second stream, cooling the composite stream to a temperature at which the material of the substreams will orient and subsequently drawing the composite stream to a degree sufficient to provide mono-directional orientation within the material of the sub-streams, thereby providing a composite article comprising a matrix having a plurality of spaced-apart members of a high tensile material in a matrix of a higher elongation, material. Said plurality of substreams may form a three-dimensional pattern. The first stream of material may be nylon or crystalline polyvinylidene chloride and the second stream may be polyethylene, rubber; plasticized polyvinyl chloride or ethyl cellulose. Suitably the first stream of material is nylon 66 and the second stream is polyethylene, polyvinyl chloride or a blend of 80 parts of polystyrene and 20 parts of butadiene rubber. Alternatively, the first stream of material may be nylon 6 and the second stream a copolymer of 85 parts vinyl chloride and 15 parts vinyl acetate. The first stream may also be polypropylene and the second polyethylene, a copolymer of 80 parts polyvinyl chloride and 20 parts butyl acrylate or a blend of 80 parts polystyrene and 20 parts butadiene rubber. The first stream may alternatively be polystyrene and the second stream polyethylene. Again, the first stream may be a copolymer of 90 parts vinylidene chloride and 10 parts vinyl chloride and the second stream a copolymer of 85 parts vinyl chloride and 15 parts vinylidene chloride. Figs. 4, 10 and 11 illustrate reinforced film and sheet materials obtained by the process of the invention, while Figs. 7, 8 and 9 illustrate filamentary or cord-like materials obtained by the process of the invention. In Fig. 1, extruders 11 and 12 deliver first and second streams of thermoplastic resinous material via conduits 14 and 15 to die 17 having an extrusion orifice 18 from which issues a composite stream 20 of thermoplastic resinous material, which is cooled by cooling means 21 to an orientation temperature and oriented by passage around rolls 27, 28 and 29, which are driven by means not shown at successively increasing surface speed, and the composite thermoplastic article 20a produced is taken up on wind-up means 33. Die 17 is shown in more detail in Fig. 2. Conduit 14 communicates with passageway 36 and converging passageway 37 terminating in extrusion orifice 18. Conduit 15 communicates with a second or inner passageway 41 which terminates in a plurality of extrusion orifices 42. Fig. 3 shows chamber 41 and the extrusion orifices 42 in more detail. Operation results in the product shown in Fig. 4. The appatatus of Fig. 5 enables three streams of polymeric material to be used, to yield the product shown in Fig. 7. Material supplied via conduit 64 passes to chamber 63 and thence through channels 66 and is extruded as an assembly of filamentary elements (82 in Fig. 7). The elements are encapsulated by material 81 which is supplied via conduit 66 to chamber 68. The outer layer 84 is formed from material supplied at passageway 70 to annular cavity 71, the conjugate filament being extruded at 74. Modified forms of the apparatus of Figs. 2 and 5 enable the production of the materials shown in Figs. 8, 9, 10 and 11. Such material may have the form of films or sheets, or of filaments, thicker mono-filaments of concentric conjugate construction, or thicker materials suitable for use as guy lines. High strength mono-directionally oriented articles are thus readily fabricated from a wide variety of thermoplastic materials, the critical features being that for a tape, filament or body of maximum physical resistance the encapsulated phase should be monodirectionally oriented to a maximum degree while the encapsulating phase is maintained with a minimum orientation. Thus, stretching temperatures are selected to favour the orientation of the encapsulated material. In this manner, a relatively high proportion of high strength material is incorporated into a body of non-oriented material which thus prevents fibrillation, so that an essentially mono-directionally oriented product is obtained of high tensile strength.