Apparatus and Method for Filter Manufacture

Abstract

A filter rod for a smoking article comprising an extruded hardened tubular element formed from a filter material with entrained cured plasticiser, and a continuous core of filler material provided within the tubular element. Also disclosed is an apparatus for manufacturing such a filter rod, the apparatus comprising a duct having an inlet to receive filter tow material and plasticiser, and an outlet. The duct tapers between the inlet and the outlet. A mandrel is disposed at least partially within the duct and is fixed relative to the duct. The mandrel is hollow and includes an internal passage extending though the mandrel through which a filler material may be conveyed. The passage includes an outlet at a distal end of the mandrel though which the filler material may be expelled. A heating zone is configured to heat filter material. The apparatus is configured such that filter tow material and plasticiser conveyed through the duct is compressed around the mandrel into a tubular rod, and filler material fed though the internal passage of the mandrel is expelled out of the passage outlet to fill the bore of the tubular rod. The tubular rod is heated in the heating zone to at least partially cure the plasticiser, to produce a continuous filter rod comprising a tubular rod of hardened filter material with a continuous core of filler material. Also disclosed is a method of manufacture of such a filter rod.

1 . A filter rod for a smoking article wherein the filter rod comprises a filter segment or may be cut to form individual filter segments, and wherein the filter rod is an extruded hardened tubular element formed from a filter material with entrained cured plasticiser, and a continuous core of filler material provided within the tubular element. 
     
     
         2 . A filter rod according to  claim 1  wherein the filter material comprises cellulose acetate tow which is hardened with a plasticiser. 
     
     
         3 . A filter rod according to  claim 1  wherein the filter rod does not comprise any outer wrap around the tubular element. 
     
     
         4 . A filter rod according to  claim 1  wherein the filler material of the core comprises cellulose acetate. 
     
     
         5 . A filter rod according to  claim 1  wherein the filler material comprises a granular aerosol modifying material. 
     
     
         6 . A filter rod according to  claim 1  wherein the filler material comprises tobacco or a derivative of tobacco. 
     
     
         7 . A filter for a smoking article comprising a filter rod according to  claim 1 , and a second filter segment axially aligned with the filter rod and joined thereto by a plug wrap around the filter rod and second filter segment. 
     
     
         8 . A smoking article comprising a tobacco rod and a filter rod or filter according to  claim 1  joined to one end of the tobacco rod. 
     
     
         9 . An apparatus for manufacturing an extruded filter rod for smoking articles, the apparatus comprising:
 a duct having an inlet configured to receive filter tow material and plasticiser, and an outlet, the duct tapering between the inlet and the outlet;   a mandrel disposed at least partially within the duct and fixed relative to the duct;   wherein the mandrel is hollow and includes an internal passage extending though the mandrel through which a filler material may be conveyed;   the passage including an outlet at a distal end of the mandrel though which the filler material may be expelled; and   a heating zone configured to heat filter material;   the apparatus configured such that filter tow material and plasticiser conveyed through the duct is compressed around the mandrel into a tubular rod, and filler material fed though the internal passage of the mandrel is expelled out of the passage outlet to fill the bore of the tubular rod, and the tubular rod is heated in the heating zone to at least partially cure the plasticiser, to produce a continuous filter rod comprising a tubular rod of hardened filter material with a continuous core of filler material.   
     
     
         10 . An apparatus according to  claim 9  wherein the internal passage of the hollow mandrel includes a tapered section which narrows in a direction towards the distal end of the mandrel. 
     
     
         11 . An apparatus according to  claim 9  wherein the outer dimension of the hollow mandrel includes a tapered section which narrows in a direction towards the distal end of the mandrel. 
     
     
         12 . An apparatus according to  claim 9  wherein a distance between an outer surface of the mandrel and an inner surface of the duct reduces along at least a part of the length of the duct in a direction towards the distal end of the mandrel. 
     
     
         13 . An apparatus according to  claim 9  wherein the distal end of the mandrel is positioned downstream of the outlet of the duct. 
     
     
         14 . An apparatus according to  claim 9  wherein the mandrel extends entirely through the length of the duct. 
     
     
         15 . An apparatus according to  claim 9  wherein the distal end of the mandrel is positioned within the duct. 
     
     
         16 . An apparatus according to  claim 15  wherein the mandrel extends into the heating zone. 
     
     
         17 . An apparatus according to  claim 16 , wherein the duct comprises first and second sections, wherein the first section tapers from the inlet to the second section, and the second section is of constant cross-section, and wherein the distal end of the mandrel is disposed within the second section. 
     
     
         18 . An apparatus according to  claim 15 , wherein the distal end of the mandrel is disposed within the heating zone. 
     
     
         19 . An apparatus according to  claim 9  wherein the mandrel is disposed coaxially with the duct. 
     
     
         20 . An apparatus according to  claim 9  wherein the heating zone comprises a steam supply to heat the filter material and plasticiser. 
     
     
         21 . An apparatus according to  claim 20  wherein the heating zone includes a steam chamber formed around a section of the duct, and the duct includes steam vents to allow steam supplied to the steam chamber to pass into the duct to directly heat the filter material. 
     
     
         22 . An apparatus according to  claim 9  further comprising a post-curing treatment station downstream of the heating zone with respect to the conveyance direction of the extruded continuous filter rod, the post-curing treatment station configured to further smooth the outer surface of the extruded continuous filter rod. 
     
     
         23 . An apparatus according to  claim 22  wherein the post-curing treatment station comprises an electrical heater configured to heat the outer surface of the continuous filter rod. 
     
     
         24 . An apparatus according to  claim 23  wherein the electrical heater is configured to heat the outer surface of the continuous filter rod to between 100-200 degrees Celsius. 
     
     
         25 . An apparatus according to  claim 23  wherein the post-curing treatment station is configured to melt the plasticiser on the outer surface of the continuous filter rod so that the melted outer surface can subsequently set as a smooth finish. 
     
     
         26 . An apparatus according to  claim 22  wherein the post-curing treatment station comprises a spray-coating station including a spray nozzle and a source of liquid treatment connected to the spray nozzle to spray the liquid treatment onto the outer surface of the continuous filter rod to form a smooth outer coating. 
     
     
         27 . An apparatus according to  claim 26  wherein the liquid treatment sprayed from the spray nozzle comprises a plasticiser, and may comprise triacetate. 
     
     
         28 . An apparatus according to  claim 9  further comprising a cutting station configured to cut the continuous extruded filter rod into discrete filter rods. 
     
     
         29 . A method of manufacturing extruded filters for smoking articles, the method comprising feeding filter tow material and plasticiser into an inlet of a duct, the duct tapering between the inlet and an outlet, conveying the filter tow material through the duct and around a hollow mandrel disposed at least partially within the duct and fixed relative to the duct, such that the filter material is compressed into a tubular rod, conveying a filler material along an internal passage extending through the hollow mandrel, expelling the filler material from an outlet of the internal passage at a distal end of the mandrel to fill the bore of the tubular rod with the filler material, and heating the tubular rod to at least partially cure the plasticiser to produce a continuous filter rod comprising a tubular rod of hardened filter material with a continuous core of filler material. 
     
     
         30 . A method according to  claim 29  comprising expelling the filler material from the internal passage outlet at the distal end of the mandrel downstream of the outlet of the duct. 
     
     
         31 . A method according to  claim 29  comprising expelling the filler material from the internal passage outlet at the distal end of the mandrel within the duct, upstream of the duct outlet. 
     
     
         32 . A method according to  claim 29  comprising heating the filter material and plasticiser in a heating zone of the apparatus using steam. 
     
     
         33 . A method according to  claim 32  comprising heating the filter material in the heating zone to at least partially cure the plasticiser before filling the bore of the tubular rod with the filler material. 
     
     
         34 . A method according to  claim 29  comprising compressing the filter tow material to at least partially form the tubular rod before filling the bore of the tubular rod with the filler material. 
     
     
         35 . A method according to  claim 29  comprising providing cellulose acetate tow as the filler material. 
     
     
         36 . A method according to  claim 29  comprising providing a pre-formed filter rod through the mandrel as the filler material. 
     
     
         37 . A method according to  claim 29  comprising providing tobacco as the filler material. 
     
     
         38 . A method according to  claim 29  further comprising performing a post-curing treatment on the continuous filter rod to provide the continuous filter rod with a smoother outer surface than the surface texture present when expelled from the heating region. 
     
     
         39 . A method according to  claim 38  wherein the post-curing treatment comprises heating the outer surface of the continuous filter rod with an electrical heater and smoothing the outer surface. 
     
     
         40 . A method according to  claim 39  wherein the post-curing treatment comprises heating the outer surface sufficiently to melt the plasticiser on the outer surface of the continuous filter rod and subsequently setting the melted outer surface as a smooth finish. 
     
     
         41 . A method according to  claim 40  comprising heating the outer surface of the continuous filter rod to between 100-200 degrees Celsius. 
     
     
         42 . A method according to  claim 38  wherein the post-curing treatment comprises spray-coating a liquid treatment onto the outer surface of the continuous filter rod to form a smooth outer coating. 
     
     
         43 . A method according to  claim 42  comprising spraying a plasticiser, which may comprise triacetate, onto the outer surface of the continuous filter rod. 
     
     
         44 . A method according to  claim 29  further comprising cutting the continuous extruded filter rod into discrete filter rods.