METHOD OF PRODUCING THREE-LAYER FILM BASING ON POLYPROPYLENE WITH FILLER FROM CALCIUM CARBONATE Russian patent published in 2016 - IPC B29D7/01 B29C47/06 B32B27/32 B32B27/06 B32B27/18 

FIELD: manufacturing technology.

SUBSTANCE: invention relates to extrusion methods of producing multilayer filled thermoplastic films and can be used for producing by flat-slot extrusion multilayer polypropylene films with a filler from calcium carbonate for further making articles, in particular for packaging and disposable plastic ware. Method of producing a three-layer film basing on polypropylene with a filler from calcium carbonate involves dosed supply of initial components into an extruder, stirring, the mixture plasticizing until obtaining a melt, the melt separation into layers with its supply through a flat-slot extrusion head and forming a film. Polypropylene, a dye and calcium carbonate are used as the initial components, which are dosed into a two-screw extruder and a co-extruder in two stages. At the first stage the two-screw extruder is loaded with polypropylene, and the co-extruder is loaded with polypropylene with the dye. Then the components are mixed in the extruders using screws with decreasing depth of thread, the loaded mass is plasticized with additional heating. Then at the second stage in the two-screw extruder the polypropylene melt is added with calcium carbonate, mixed till homogeneous mass, then it is degassed. Then both molten flows from both extruders are introduced through appropriate inlet holes into an adapter, where the melt flow from the co-extruder is divided into two flows and the melt flow from the two-screw extruder is directed between them, and fed into the flat-slot extrusion head to produce at the outlet a three-layer fabric, from which the film is formed using the a calender.

EFFECT: proposed is a method of producing a three-layer film basing on polypropylene with a filler from calcium carbonate.

1 cl, 1 dwg