Method of and device for admixing finely divided dye stuff into a synthetic granulate

Claim 1

A method of admixing a finely divided dye stuff to a stream of synthetic granulate comprising the steps of feeding a densely packed stream of said granulate through an interspace formed between an inner wall of a fall shaft and an outer wall of an upright filling channel, the fall shaft communicating with an inlet of an extruder and the filling channel having an outlet opening into the fall shaft at a distance above said inlet, whereby a sloping cavity is continuously formed within said stream of granulate below the outlet of said filling channel; and dosing the dye stuff and feeding said dye stuff by free fall through said filling channel into said cavity.

Claim 2

A method of admixing a finely divided dye stuff to a stream of synthetic granulate comprising the steps of feeding a densely packed stream of said granulate through an interspace formed between an inner wall of a fall shaft and an outer wall of an upright filling channel, the fall shaft communicating with an inlet of an extruder and the filling channel having an outlet opening into the fall shaft at a distance above said inlet, whereby a sloping cavity is continuously formed within said stream of granulate below the outlet of said filling channel; and dosing the dye stuff and feeding said dye stuff by free fall through said filling channel into said cavity.

Claim 4

A device for mixing a finely divided dye stuff into a stream of synthetic granulate fed into an extruder, comprising a filling shaft for the synthetic granulate, the filling shaft including an inclined upper part and a vertical lower part communicating with an intake opening of the extruder; a vertical filling channel for the dye stuff arranged above and communicating with the vertical lower part of the filling shaft; the ratio of cross-sections of said lower part of the filling shaft and said filling channel being smaller than 6:1 to produce a funnel-shaped cavity in the stream of synthetic granulate below said filling channel; and said vertical filling channel having an inlet provided with a funnel for feeding against sloping walls of said cavity a narrow string of the dye stuff free falling substantially along a center axis of the filling channel.

Claim 5

A device for mixing a finely divided dye stuff into a stream of synthetic granulate fed into an extruder, comprising a filling shaft for the synthetic granulate, the filling shaft including an inclined upper part and a vertical lower part communicating with an intake opening of the extruder; a vertical filling channel for the dye stuff arranged above and communicating with the vertical lower part of the filling shaft; the ratio of cross-sections of said lower part of the filling shaft and said filling channel being smaller than 6:1 to produce a funnel-shaped cavity in the stream of synthetic granulate below said filling channel; and said vertical filling channel having an inlet provided with a funnel for feeding against sloping walls of said cavity a narrow string of the dye stuff free falling substantially along a center axis of the filling channel.