Method for applying liquid plasticizer to filamentary filter material

摘要

A filter rod making machine wherein a rotary brush which is installed in a housing normally atomizes successive increments of a stream of liquid plasticizer which is supplied thereto by a varibale-delivery pump at a rate matching the speed of transport of a permeable tow of filamentary filter material through the housing so that the housing confines a quantity of residual plasticizer and the tow thereafter continuously withdraws atomized plasticizer from the housing at the rate at which the pump supplies liquid plasticizer into the range of the brush. When the tow is arrested, at least some of the residul plasticizer is evacuated from the housing and, on renewed starting of the prime mover which drives the tow, the plasticizer is admitted at a rate higher than normal rate, either by resorting to a separate pump or by gathering the evacuted residual plasticizer during the interval of idleness of the prime mover and readmitting the gathered residual plasticizer into the housing during acceleration of the tow to normal speed so as to rapidly reestablish the quantity of residual plasticizer which is necessary to ensure that a state of internal equilibrium prevails in the housing, namely, that the rate of admission of liquid plasticizer into the range of the brush again equals the rate at which the running tow removes atomized plasticizer from the housing.