Synthetic monofilament bristle for toothbrushes has cross-section with different regions separated by zones of weakness to encourage fracture

摘要

Monofilament bristles, especially for electric toothbrushes, have a cross-section with at least two regions (6,7) and a zone of weakness (8) between them to encourage separation when the ends of the bristles are worked mechanically, e.g. rounded. The resultant split extends to 10 - 25% of the bristle length. The cross-section can be non-circular, e.g. clover leaf, and can have hollow regions. An Independent claim is also included for the process of making such bristles, e.g. by separating the extruded stream and rejoining it in the extrusion die or by extruding different materials side by side.