Method of producing thick-walled brushes, in particular toothbrushes

A method of producing brushes with a grip piece and a brush head for supporting bristle filaments, comprising the steps of:

• initially producing a unitary basic body of a hard plastic material including a grip-handle core, a neck area and a brush head in a first injection molding cycle in a first die cavity,
• transferring said basic body to a larger die cavity, and
• circumferentially surrounding the grip-handle core with a cover layer of a hard plastic material in a subsequent injection molding cycle to form a multi-layered grip piece of hard plastic material wherein the grip-handle core and the hard plastic material layered on top of the circumference of the grip-handle core in the subsequent injection molding cycle are dimensioned such that the times between injection and cooling to a temperature to permit the basic body and the basic body with the layer on the grip-handle core to be removed from the respective mold in a dimensionally stable form are approximately equal for the formation of the grip-handle core and for the formation of the basic body with the layer of hard plastic material on the grip-handle core,
• wherein the layer of hard plastic material applied on the grip-handle core has a thickness in the range from 15-50% of the thickness of the grip-handle core,
• and wherein in a further injection molding cycle, the cover layer enclosing the grid-handle core is encompassed by another layer of plastic material formed by injection molding.