Patent GB-1236097-A (GB)
Title: Process and apparatus for the manufacture of films and yarns, and the products thus manufactured
Inventor: FONTIJN WILHEMUS JOHANNES
IPC: B29C48/05
Filed: 1968-07-11
Abstract: 1,236,097. Synthetic films and yarns. ALGEMENE KUNSTZIJDE UNIE N.V. 11 July, 1968 [12 July, 1967], No. 33133/68. Heading B5B. Synthetic films are made by a process in which at least two liquid component polymers are placed side by side in a given order to form a single main stream which is repeatedly flattened and divided to form a multi-layer stream which is forced through an extrusion slit, which in the longitudinal direction thereof extends substantially perpendicular to the planes of the divisions between the layers to form a film in which the layers extend side by side across the film. Advantageously, the layered stream, which has a virtually square cross-section, is transformed at least once while the cross-sectional surface area is maintained constant, into a stream having a rectangular cross-section whose short-side dimension is not smaller than 1 mm. The process is more particularly characterized in that the main stream is made up of at least three components, at least two of which properly adhere to each other in the extruded film but differ widely in shrinkability after drawing in the longitudinal direction of the film and of which at least one other component which hardly adheres to its neighbouring components is present between the components which do not adhere to each other. As the said other component use may be made of a material which is soluble in solvents which do not attack the components that adhere to each other and the film, after it has been drawn or not, is passed through a bath containing these solvents. The said other component may have a melting point which is lower than the softening point of the components which adhere and the film, after it has been drawn or not, is heated. The material for the other component may have an elongation at its breaking point which is lower than that corresponding to the ratio at which the adhering components are drawn, and the film is then drawn. In another embodiment, the main stream is composed of at least 3 components of which in the formed film at least two poorly adhere to each other, and of which at least one other component which properly adheres to its neighbouring components is present between the two poorly adhering components. Threads, fibres or yarns can be made from the film by splitting each film sheet into a large number of threads by a mechanical, chemical or physical treatment. In the examples, the following films are described: (i) a two-component film of nylon 6, and nylon 6 and polystyrene, the polystyrene thereafter being removed, thus forming a fibre sheet, (ii) a two-component film of nylon 6 and polyethylene, the polyethylene thereafter being entirely or partially removed after which the film may be processed into a spun yarn, (iii) a three-component film of nylon 6, polyethylene terephthalate, and copolyesteramide which latter component properly adheres to the first two poorly adhering components, (iv) a three component film of nylon 6, a copolyamide of nylon 6 and 11, and polystyrene, which film can be readily fiberized and split after removal therefrom of polystyrene.