GB853871A - Process and apparatus for the production of artificial filaments - Google Patents

Abstract

The process of the parent Specification (wherein monofilaments of a thermoplastic organic high polymer, such as polystyrene, discharged from an extrusion die head are adjusted to their orientation temperature by contacting the filaments with a heated moving surface and are thereafter stretched at this temperature) is modified in that the cross-section of the filaments comprises at least three webs or ribs radially disposed with respect to a central core portion, the diameter of which is of the same order of magnitude as the thickness of the webs or ribs, the monofilaments being formed by melt-spinning the polymer through orifices having a shape adapted to impart to the filaments the desired cross-section. The filaments are stretched while being maintained at the temperature at which they are to be oriented, which may be between 210 DEG and 300 DEG F. The web or rib portions of the monofilaments are preferably of considerable radial length compared with the diameter of the core portion and are preferably regularly disposed radially to the core of the monofilament. The webs or ribs may all be of equal thickness and of uniform thickness from their roots to their free ends. They are also preferably of equal length radially. The unoriented extruded filaments may be brought to the desired orientation temperature by passing them in a sinuous path over a series of hollow driven rolls maintained at a predetermined temperature by the circulation of steam through them. The filaments of the invention retain more liquid and are stiffer per unit weight and length than filaments of circular cross-section and are thus more suitable for the manufacture of paint brushes and scrubbing brushes. They are also more easily split longitudinally at their ends.