Tobacco reconstitution

Abstract

The invention relates to the extrusion of filamentary strands of reconstituted tobacco through a die plate and the downstream handling thereof. The die plate is configured such that each filament is of a square or rectangular cross-section, the downstream handling of which effects draw down of the extruded filament.

1 . A method of handling an extruded reconstituted tobacco filament downstream of die means through which said filament is being extruded, wherein said filament is transferred in a direction longitudinal of said filament away from said die by pneumatic conveyance means, said conveyance means effecting draw down of said filament such that the cross-sectional dimensions of said filament are reduced.  
     
     
         2 . A method according to  claim 1 , wherein said extruded filament is cut transversely at intervals along the length thereof into a plurality of elements.  
     
     
         3 . A method according to  claim 2 , wherein said elements are cut at intervals in the range of about 10 mm to about 50 mm.  
     
     
         4 . A method according to  claim 2  or  3 , wherein said extruded filament is cut subsequent to the reduction in the cross-sectional dimensions of said filament.  
     
     
         5 . A method according to any one of claims  2 - 4 , wherein cutting means utilised in the cutting step is a rotary cutter.  
     
     
         6 . A method according to any one of the preceding claims, wherein cooling air is brought into contact with said extruded filament to effect cooling thereof.  
     
     
         7 . A method according to  claim 6 , wherein the temperature of said extruded filament when cut is within the range of about 20° to about 60° Celsius.  
     
     
         8 . A method according to  claim 7 , wherein said temperature is in the range of about 30° to about 50° Celsius.  
     
     
         9 . A method according to any one of the preceding claims, wherein said pneumatic conveyance means comprises gaseous medium transfer means and duct means, said transfer means being operable to cause transfer of a gaseous medium, as a continuous flow through said duct means.  
     
     
         10 . A method according to any one of the preceding claims, wherein the transfer in a direction longitudinal of said filament is initially perpendicular to the die face of said die means.  
     
     
         11 . A method according to  claim 10 , wherein after the transfer perpendicular to the die face, the transfer is in a substantially horizontal or vertical plane.  
     
     
         12 . A method according to any one of the preceding claims, wherein draw down of said filament is effected by the velocity of the gaseous medium flowing in a direction which corresponds with the transfer direction of said filament being greater than the extrusion velocity.  
     
     
         13 . A method according to  claim 12 , wherein said velocity of said gaseous medium is in the range of 60-180 m/s.  
     
     
         14 . A method according to  claim 13 , wherein said velocity is at least 100 m/s.  
     
     
         15 . A method according to any one of claims  11 - 13 , wherein the draw down of said filament is enhanced by tensioning said filament further by drawing said filament over tensioning means.  
     
     
         16 . A method according to  claim 14 , wherein said tensioning means is a driven roller.  
     
     
         17 . A method according to any one of the preceding claims, wherein the conveying velocity after draw down of said filament is in the range of 30-60 m/s.  
     
     
         18 . A method according to  claim 17 , wherein said conveying velocity is at least 35 m/s.  
     
     
         19 . A method according to  claim 18 , wherein said conveying velocity is in the range of 40-60 m/s.  
     
     
         20 . A method according to any one of claims  9 - 19 , wherein a pneumatic conveyance means configuration and a mass airflow valve are selected such that said filament(s) does not, in its transference through said duct means, come into contact with any inner surface of said duct means.  
     
     
         21 . A tobacco filament made in accordance with the method of any one of claims  1 - 20 , wherein said extruded tobacco filament is of rectangular or square cross-section.  
     
     
         22 . A tobacco filament made in accordance with the method of any one of claims  2 - 21 , wherein the cross section of said filament following draw down thereof, has dimensions of about 0.7 mm by about 1 mm.  
     
     
         23 . A tobacco filament according to  claim 22 , wherein said dimensions are about 0.3 mm by about 0.8 mm.  
     
     
         24 . An extruder die plate comprising die orifices, said die orifices being of a generally square or rectangular configuration, and the sides of the square or rectangle being concave.  
     
     
         25 . An extruder die plate according to  claim 24 , wherein said die orifices are arranged in such a manner that the extruded filaments issuing therefrom are in a side-by-side array.  
     
     
         26 . An extruder die plate according to claims  23  or  24 , wherein the exit face of said die plate is oblong in configuration and the exit orifices thereof are arranged in a single row across the face.  
     
     
         27 . An extruder die plate according to claims  23  or  24 , wherein the exit face of said die plate is oblong in configuration and the exit orifices thereat are arranged in two, upper and lower, longitudinal rows, the orifices of the upper row being vertically out of registration with the orifices of the lower row.  
     
     
         28 . An extruded reconstituted tobacco filament, wherein said filament is of a substantially rectangular or square cross-section.  
     
     
         29 . An extruded reconstituted tobacco filament according to  claim 23 , comprising a cellular interior and an integral skin extending over at least the four sides of said filament.  
     
     
         30 . An extruded reconstituted tobacco filament according to  claim 28  or  29 , wherein the cross-section of said filament has dimensions of about 0.7 mm by 1 mm.  
     
     
         31 . An extruded reconstituted tobacco filament according to  claim 30 , wherein said dimensions are about 0.3 mm by about 0.8 mm.  
     
     
         32 . A filamentary reconstituted tobacco product consisting of lengths of a filament comprising a cellular interior and an integral skin extending over, when the filament is of a square or oblong cross-section, at least the four longitudinal sides of the filament.  
     
     
         33 . A filamentary reconstituted tobacco product according to  claim 32 , wherein said product has a filling value in the range of about 3.8 to about 5.0 mm 3 /mg.  
     
     
         34 . A filamentary reconstituted tobacco product according to  claim 33 , wherein said filling value is in the range of about 4.0 mm 3 /mg to about 4.6 mm 3 /mg.  
     
     
         35 . A filamentary reconstituted tobacco product according to any one of claims  32 - 34  and having a density in the range of about 150 mg/mm 3  to about 600 mg/mm 3 .  
     
     
         36 . A filamentary reconstituted tobacco product according to  claim 35 , wherein said density is less than about 400 mg/mm 3 .  
     
     
         37 . A method according to any one of claims  1 - 20 , in conjunction with an extruder die plate of any one of claims  24 - 27 , wherein the concavity of said orifices of said die plate is such that there is produced a filament, the cross-sectional shape of which is a straight-sided square or rectangle.  
     
     
         38 . A method according to any one of claims  1 - 20  or  claim 37 , wherein a plurality of reconstituted tobacco filaments are co-extruded by means of a die comprising a plurality of exit orifices.  
     
     
         39 . A method according to  claim 37  or  38 , wherein the exit orifices of said die are arranged in such a manner that the filaments issuing therefrom are in a side-by-side array.  
     
     
         40 . An extruded filamentary tobacco pneumatic conveyance means comprising in combination gaseous medium transfer means and duct means, the transfer means being operable to cause transfer of gaseous medium, as a continuous flow thereof, through the duct means, and an extruder comprising a die plate arranged to produce a plurality of filaments, wherein the inlet end of said duct means is positioned adjacent to said extruder die plate such that when said filaments emerge from the die orifice, said filaments are readily transferred in a direction longitudinal of said filaments away from said die plate under the action of said continuous flow of gaseous medium through said duct means, wherein a plurality of filaments are able to travel side-by-side of one another through said duct, said conveyance means effecting draw down of said filament such that the cross-sectional dimensions of said filament are reduced.  
     
     
         41 . An extruded filamentary tobacco pneumatic conveyance means according to  claim 40 , wherein said inlet end of said duct means is located within about 5 mm-20 mm from said extruder die.  
     
     
         42 . An extruded filamentary tobacco pneumatic conveyance means according to  claim 41 , wherein said inlet end of said duct means is located within the range of about 10 mm-about 15 mm from said extruder die.  
     
     
         43 . An extruded filamentary tobacco conveyance means according to any one of claims  40 - 42 , wherein said side-by-side arrangement is horizontal.  
     
     
         44 . An extruded filamentary tobacco pneumatic conveyance means according to any one of claims  40 - 43 , wherein said duct means has an oblong cross-section suitable to allow a plurality of filaments to travel side-by-side of one another through said duct.  
     
     
         45 . An extruded filamentary tobacco pneumatic conveyance means according to any one of claims  40 - 44 , wherein said die plate is that of claims  24 - 27 .  
     
     
         46 . A smoking article comprising a filamentary reconstituted tobacco product according to any one of claims  32 - 36 .