Patent ID: 7021025

Claim:
A method for producing a filter bag for containing a substance for infusion in a liquid, said method comprising: feeding in a predetermined feed direction and parallel with one another: a filter paper web, a cotton thread positioned longitudinally to and opposite the filter paper web and a succession of tags, the tags being placed along the web at predetermined intervals; forming on the thread a succession of first winding loops, separated by an interval corresponding to the tag interval; connecting the first winding loops of thread to the pick-up tags, and connecting the pick-up tags to the paper web; folding the filter paper web over itself in a direction away from the thread and tag so that longitudinal edges of the filter paper web which were initially opposite one another are overlapping, gradually forming a filter paper tube in which the thread and tag are on the outside of said tube; depositing a succession of doses of the substance for infusion on the web, before the tube is definitively formed; connecting the longitudinal edges of the tube to one another; making pairs of transverse connections on the tube, upstream and downstream of each tag, designed to delimit a succession of sealed containment chambers containing at least one dose of the substance for infusion; securing the sections of thread between the transverse connections to the tube; cutting the filter paper web at a predetermined distance from one of said pickup tags to form a slit; and, forcing the thread through the slit to form a second loop projecting from the filter paper web on a side opposite that in contact with the thread.