CA2049573C - Uniform tar delivery profile filter - Google Patents
Uniform tar delivery profile filterInfo
- Publication number
- CA2049573C CA2049573C CA002049573A CA2049573A CA2049573C CA 2049573 C CA2049573 C CA 2049573C CA 002049573 A CA002049573 A CA 002049573A CA 2049573 A CA2049573 A CA 2049573A CA 2049573 C CA2049573 C CA 2049573C
- Authority
- CA
- Canada
- Prior art keywords
- smoke
- cigarette
- filter element
- filter
- cylinder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- A—HUMAN NECESSITIES
- A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
- A24D—CIGARS; CIGARETTES; TOBACCO SMOKE FILTERS; MOUTHPIECES FOR CIGARS OR CIGARETTES; MANUFACTURE OF TOBACCO SMOKE FILTERS OR MOUTHPIECES
- A24D3/00—Tobacco smoke filters, e.g. filter-tips, filtering inserts; Filters specially adapted for simulated smoking devices; Mouthpieces for cigars or cigarettes
- A24D3/04—Tobacco smoke filters characterised by their shape or structure
Abstract
A tobacco smoke filter element produces a more uniform tar delivery profile without an unacceptable pressure drop by causing the cigarette smoke to assume a progressively longer flow path through an outer cylinder of higher flow resistance filter tow material before passing radially inwardly through a cylinder of microfine fibres into a low resistance flow path to the smoker's mouth. The progressively increased flow path results from progressive clogging of the cylinder of microfine fibres by filtered material as smoking of the cigarette progresses.
Description
204~73 UNIEORM TAR DELIVERY PROFILE FILTER
The present invention relates to a novel cigarette smoke filter element which is able to provide a more uniform- tar ~delivery profile to the smoker than has heretofore been possible, and to cigarettes incorporating such filter elements.
It is well known that when either a smoker or a smoking machine smokes a conventional filter-tipped cigarette, the amount of "tar" in each puff increases in each successlve puff. The "tar" yield of the last few puffs is usually several times higher than that from the first few puffs. Consequently the "tar" in the last few puffs may be perceived by a smoker as "too strong", and a smoker, therefore, may consider a cigarette as "smoother", if the "tar" delivery profile can be made more even.
There have been many attempts in the past to achieve an "even" puff cigarette by modifying the filter.
Mullor, ~J.S. Patent no. 2,763,267 and Clayton et al, U.S.
Patent no. 3, 809, 097 proposed to use a plurality of discs to be placed inside a cigarette filter rod and placed transverse to the smoke flow. These designs, however, can only improve filtration efficiency, but without any ability of evening the cigarette "tar" profile.
Patterson, U.S. Patent no. 3, 648, 712 proposed to use a low gas permeability disc placed transversely inside an ordinary cellulose acetate filter rod. The disc is of a diameter which is 5 to 25 percent less than the diameter of the filter rod and this filter, therefore, can only achieve improved filtration efficiency, with no ability to even the "tar" delivery profile.
The present invention relates to a novel cigarette smoke filter element which is able to provide a more uniform- tar ~delivery profile to the smoker than has heretofore been possible, and to cigarettes incorporating such filter elements.
It is well known that when either a smoker or a smoking machine smokes a conventional filter-tipped cigarette, the amount of "tar" in each puff increases in each successlve puff. The "tar" yield of the last few puffs is usually several times higher than that from the first few puffs. Consequently the "tar" in the last few puffs may be perceived by a smoker as "too strong", and a smoker, therefore, may consider a cigarette as "smoother", if the "tar" delivery profile can be made more even.
There have been many attempts in the past to achieve an "even" puff cigarette by modifying the filter.
Mullor, ~J.S. Patent no. 2,763,267 and Clayton et al, U.S.
Patent no. 3, 809, 097 proposed to use a plurality of discs to be placed inside a cigarette filter rod and placed transverse to the smoke flow. These designs, however, can only improve filtration efficiency, but without any ability of evening the cigarette "tar" profile.
Patterson, U.S. Patent no. 3, 648, 712 proposed to use a low gas permeability disc placed transversely inside an ordinary cellulose acetate filter rod. The disc is of a diameter which is 5 to 25 percent less than the diameter of the filter rod and this filter, therefore, can only achieve improved filtration efficiency, with no ability to even the "tar" delivery profile.
2 2~ 7~
B.A.T. GB Patent no. 1,339,238 proposed placing a disc of a blocking plug between a tobacco rod and an ordinary cellulose acetate filter rod. This disc has an orifice for smoke to flow through. The disadvantage of 5 this design is that the pressure drop of the cigarette increases to an unacceptable level as the orif ice of the plug becomes clogged up at the later puf f s .
Brackmann et al,. U.S. Patent no. 3,882,877 proposed placing a disc of microfine fibres in between 10 two filter rod segments. This filter is designed to increase filtration efficiency. However, it could not cause the "tar" delivery to be more even, furthermore the pressure drop may increase to an unacceptable level at the later puf f s .
Browne et al., U.S. Patents nos. 4,460,000 and 4,469,112 proposed using a compound filter that contains a perforated barrier disc through which the whole smoke passes to a cellulose acetate filter rod segment. As the smoking process proceeds, more and more "tar" builds up on the cellulose acetate f ibres around the exit of the perforations. The disadvantage of this design is that the build-up of "tar" near the perforations will greatly increase the flow resistance of the cigarette f ilter to an unacceptable level .
G.B. Patent nos. 2,102,271 A, 2,103,065 A, and 2,105,566 A of Filtrona (U.K.), proposed to employ two flow paths, i.e. a low pressure drop path which has low f iltration ef f iciency and a high pressure drop path which has high filtration efficiency, for the smoke to flow in a filter rod. During the initial few puffs of a cigarette, it is intended that the smoke f low through the low pressure drop path. The smoke then switches to f low through the high pressure drop path due to the presence of a blocking m~ch~niF~ on the low pressure drop path. The disadvantage of these f ilters is that they are very complicated and difficult to manufacture.
~ 2049~73 U.S Patent no. 4, 747, 418 USQS a filter element in the form of a membrane having a large number of tiny openings in combination with openings downstream of the membrane through which air may be drawn or conventional 5 filter substance in an attempt to produce a more uniform tar delivery. Again a complicated and expensive structure is required.
In accordance with the present invention, an improved filter structure is provided wherein two lO different filter materials are combined to achieve a more uniform tar delivery.
Accordingly, in one aspect of the present invention, there is provided a cigarette smoke filter element, characterized by an outer elongate cylinder of tobacco 15 smoke filter material, an inner elongate cylinder of microfine fibres and an axial cigarette smoke path radially inwardly of the cylinder of microfine fibres.
The outer cylinder of smoke filter material has a greater resistance to the flow of cigarette smoke therethrough 20 than the axial flow path.
Tobacco smoke flow path directing means is located at one end of the filter element for directing cigarette smoke from a cigarette to which the filter element is attached, only into the outer cylinder of tobacco smoke 25 filter material. In this way, cigarette smoke directed from a cigarette into the outer cylinder passes first through the outer cylinder, and then through the inner cylinder into the axial low resistance flow path.
As smoking of the cigarette proceeds, the tobacco 30 smoke is forced to flow by a progressively-increasing length of flow path through the outer cylinder as a progressively greater proportion of the length of the inner cylinder becomes clogged with tar filtered from the tobacco smoke. As explained in more detail below, A
- 2 0 ~
this effect leads to a more uniform delivery of tar in the cigarette smoke to the smoker ' s mouth .
The cylinder of microfine fibres may be provided between two outer porous support layers . The microf ine 5 fibres may be formed as described in the aforementioned U. S. Patent no. 3, 882, 877, the disclosure of which i8 incorporated herein by reference. The microfine fibres in the cylindrical layer thereof may have any convenient diameter to achieve the desired filtration as described 10 herein, generally from about o . 5 to about 10 microns.
The cylindrical layer may have any convenient thickness to achieve the desired filtration as described herein, generally from about 0 . 05 to about 4 mm . The microf ine fibres may be packed to any desired degree to achieve 15 the desired filtration, generally from about 0.05 to about 0 . 3 g/cc.
The outer annulus of filter material may comprise any of the well-known filtration materials commonly employed in cigarette filters, generally cellulose 20 acetate tow with its fibres extending pr~ ~;n~ntly axially along its length, or a non-woven fibrous material, such as DANAKLON ES (polypropylene/
polyethylene bicomponent fibres made by Danaklon, Denmark ) .
The microfine fibres are a highly efficient cigarette smoke f iltration medium and function to remove liquid components from the smoke, as described more fully in U. S . Patent no . 3, 882, 877 . The f iltration is 50 efficient that the filter can rapidly become blocked 30 and permits no further smoke filtration to occur.
The latter effect is employed to advantage in the novel cigarette smoke f ilter of the invention, where the cigarette smoke is drawn in the same axial direction as the direction of extension of the cigarette filter 35 ,~ nPnts. As the first few puffs are taken, smoke enters the annulus material and then passes through the 2~4~a~3 microfine fibres into the low resistance smoke flow passage to the smoker ' s mouth . The microf ine f ibres in the area where the smoke is drawn through rapidly become clogged, 60 that the smoke is forced to assume a longer 5 path of travel through the annulus material until it can pass through the microfine fibres into the low resistance smoke path.
As the cigarette is smoked, it is necessary for the cigarette smoke to travel for progressively greater 10 di6tances in the annulus material before it can pass through the microfine fibres. A uniform amount of droplet material i5 removed from the smoke by the microfine fibres along the whole of the length of the filter, since each successive portion of the fibres is 15 able to filter out only the same maximum quantity of droplets. However, by forcing the smoke to assume a progressively longer path of travel through the annulus f ilter material progressively greater quantities of droplets are removed from the smoke aerosol. The result 20 of this filtration operation is that the smoke entering the smoker's mouth has a substantially uniform tar content and the problem of increasing tar yield from the cigarette is compensated for by providing progressively increased filtration of the tobacco smoke before it 25 reaches the smoker's mouth, without introducing an unacceptable level of pressure drop.
Accordingly, in another aspect of the present invention, there is provided a method of achieving a more uniform delivery of tar in tobacco smoke entering a 30 smoker's mouth from a cigarette, characterized by causing the tobacco smoke to pass from a burning cigarette f irst into an outer cylinder of tobacco smoke filter material of higher resistance to smoke flow, and then through an inner cylinder of microfine fibres into 35 an axial flow path to the smoker's mouth of lower resistance to smoke flow, filtering filterable 6 20~9573 materials, including tar, from the smoke both in the outer cylinder and the inner cylinder, and causing said smoke to pass through a progressively longer flow path through said outer cylinder as a progressively increased 5 proportion of the inner cylinder becomes incapable of effecting filtration, thereby to remove progressively greater proportion of filterable materials, including tar, from the tobacco smoke.
The invention is described further, by way of 10 illustration, with reference to the accompanying drawings, in which:
Figure l is a schematic sectional view of a novel cigarette filter constructed in accordance with one embodiment of the invention.
Referring to the drawing, a cylindrical cigarette 10 includes a cigarette rod 12 and a novel filter 14, having a construction which the applicants regard as the current best mode of carrying out the invention. The cigarette rod 12 has a conventional paper wrapper 16 and is joined 20 to the filter 14 by a conventional cork wrap 18.
The filter 14 comprises an outer annulus 20 of conventional cellulose acetate tow material having an outer wrap 22. A cylinder of microfine fibres 24 abuts the inner radial extremity of the annulus 20 and 25 typically is supported between outer layers of low flow resistance fabric.
The cylinder 24 is sandwiched between the annulus 20 and an inner plug 26 of low flow resistance material, such as low flow resistance acetate. The inner plug 26 30 may be omitted entirely, if desired, but preferably is employed to provide mechanicaI strength and stability to the structure. Alternative support structures may be employed, such as an extruded plastic core with a star-shaped cross-section or other convenient shape providing A
7 2~9573 smoke flow channels radially inwardly of the cylinder 24 .
At the end of the filter 14 opposite to the smoking end of the cigarette 10, the f ilter is sealed against 5 the f low of cigarette smoke directly from the cigarette rod 16 to the acetate plug 26, such as by crimping 32 the acetate plug 26, and/or by providing a circular baffle 34 overlying the end of the acetate plug 26.
The provision of such f low directing means ensures 10 that any smoke drawn by the smoker from the cigarette rod 12 enters the outer annulus 20 of acetate tow.
Since the inner plug 26 provides a lower resistance flow path for the cigarette smoke than the higher flow resistance annulus, the cigarette smoke tends to want to 15 flow radially inwardly from the resistance annulus 20 into the acetate plug 26, which results in the smoke passing through the cylinder of fibrous filter material 24 .
The 6moke follows the path of lea6t resistance so 20 that, initially, the smoke flows only for a short distance through the annulus material 20 before flowing through the microfine fibres into the acetate plug 26.
However, the microfine fibres effect efficient f iltration of the tobacco smoke to remove smoke-borne 25 particulates including tar-containing droplets and the fibres eventually are unable to effect further filtration. Accordingly, the microfine fibres in the cylinder 24 become, in the direction towards the smoking end of the cigarette 10, progressively unable to effect 3 0 f i ltration .
The cigarette smoke, therefore, is required to transverse a progressively longer path through the annulus filtration material 20 before the smoke can travel radially inwardly into the acetate plug 26. In 35 this way, a progressively greater degree of filtration is effected by the annulus material 20 and, thereby, a ~ 3 progressively greater degree of overall f iltration is effected as the cigarette 10 is smoked, thereby compensating for the progressively greater tar production by the cigarette rod 12.
In the illustrated f~r~hotl;r--nt, smoke can pass from the annulus materiAl 20 directly into the smoker's mouth. However, the predominant smoke flow path is via the acetate plug 26 because of its lower resistance to smoke flow. In addition, if desired, an annular barrier may be provided overlying the smoking end of the annulus material 20 to force all the smoke to flow to the 6moker's mouth through the acetate plug 26.
The filter element 10 may be formed in any convenient manner. In one embodiment, the acetate plug 26 is replaced by an extruded plastic core having a star-shaped cross section so as to provide a plurality of rhAnnPl c through which the filtered smoke can pass to the smoker. The plastic core then is reciprocated in front of a fine fibre extruder on a continuous basis.
The plastic core is rotated about its axis, so that the fibers are collected in an uniform layer 24 on the periphery of the core i . e., at the radial extremities of the points of the star. The relatively few microfine f ibers which may randomly extend into the air pARsa~Pc between the points of the star-shaped cross section are not sufficient to affect significantly the low pressure drop ducts between the legs of the star.
The continuous rod then i5 passed through a filter-making machine, wherein the core is periodically crimped and the normal high efficiency filter material 20 is placed on the outside of the layer 24 of microfine fibres. The filter then is wrapped in conventional plug wrap 22 and cut at the crimped points to provide a plurality of filter elements 14.
g The present invention provides a novel cigarette filter structure to provide a uniform delivery of tar to a smoker by providing for successively greater degrees of filtration as the cigarette is smoked, without producing unacceptable levels of pressure drop. Cigarettes are a staple item of commerce. Modifications are possible within the scope of this invention.
B.A.T. GB Patent no. 1,339,238 proposed placing a disc of a blocking plug between a tobacco rod and an ordinary cellulose acetate filter rod. This disc has an orifice for smoke to flow through. The disadvantage of 5 this design is that the pressure drop of the cigarette increases to an unacceptable level as the orif ice of the plug becomes clogged up at the later puf f s .
Brackmann et al,. U.S. Patent no. 3,882,877 proposed placing a disc of microfine fibres in between 10 two filter rod segments. This filter is designed to increase filtration efficiency. However, it could not cause the "tar" delivery to be more even, furthermore the pressure drop may increase to an unacceptable level at the later puf f s .
Browne et al., U.S. Patents nos. 4,460,000 and 4,469,112 proposed using a compound filter that contains a perforated barrier disc through which the whole smoke passes to a cellulose acetate filter rod segment. As the smoking process proceeds, more and more "tar" builds up on the cellulose acetate f ibres around the exit of the perforations. The disadvantage of this design is that the build-up of "tar" near the perforations will greatly increase the flow resistance of the cigarette f ilter to an unacceptable level .
G.B. Patent nos. 2,102,271 A, 2,103,065 A, and 2,105,566 A of Filtrona (U.K.), proposed to employ two flow paths, i.e. a low pressure drop path which has low f iltration ef f iciency and a high pressure drop path which has high filtration efficiency, for the smoke to flow in a filter rod. During the initial few puffs of a cigarette, it is intended that the smoke f low through the low pressure drop path. The smoke then switches to f low through the high pressure drop path due to the presence of a blocking m~ch~niF~ on the low pressure drop path. The disadvantage of these f ilters is that they are very complicated and difficult to manufacture.
~ 2049~73 U.S Patent no. 4, 747, 418 USQS a filter element in the form of a membrane having a large number of tiny openings in combination with openings downstream of the membrane through which air may be drawn or conventional 5 filter substance in an attempt to produce a more uniform tar delivery. Again a complicated and expensive structure is required.
In accordance with the present invention, an improved filter structure is provided wherein two lO different filter materials are combined to achieve a more uniform tar delivery.
Accordingly, in one aspect of the present invention, there is provided a cigarette smoke filter element, characterized by an outer elongate cylinder of tobacco 15 smoke filter material, an inner elongate cylinder of microfine fibres and an axial cigarette smoke path radially inwardly of the cylinder of microfine fibres.
The outer cylinder of smoke filter material has a greater resistance to the flow of cigarette smoke therethrough 20 than the axial flow path.
Tobacco smoke flow path directing means is located at one end of the filter element for directing cigarette smoke from a cigarette to which the filter element is attached, only into the outer cylinder of tobacco smoke 25 filter material. In this way, cigarette smoke directed from a cigarette into the outer cylinder passes first through the outer cylinder, and then through the inner cylinder into the axial low resistance flow path.
As smoking of the cigarette proceeds, the tobacco 30 smoke is forced to flow by a progressively-increasing length of flow path through the outer cylinder as a progressively greater proportion of the length of the inner cylinder becomes clogged with tar filtered from the tobacco smoke. As explained in more detail below, A
- 2 0 ~
this effect leads to a more uniform delivery of tar in the cigarette smoke to the smoker ' s mouth .
The cylinder of microfine fibres may be provided between two outer porous support layers . The microf ine 5 fibres may be formed as described in the aforementioned U. S. Patent no. 3, 882, 877, the disclosure of which i8 incorporated herein by reference. The microfine fibres in the cylindrical layer thereof may have any convenient diameter to achieve the desired filtration as described 10 herein, generally from about o . 5 to about 10 microns.
The cylindrical layer may have any convenient thickness to achieve the desired filtration as described herein, generally from about 0 . 05 to about 4 mm . The microf ine fibres may be packed to any desired degree to achieve 15 the desired filtration, generally from about 0.05 to about 0 . 3 g/cc.
The outer annulus of filter material may comprise any of the well-known filtration materials commonly employed in cigarette filters, generally cellulose 20 acetate tow with its fibres extending pr~ ~;n~ntly axially along its length, or a non-woven fibrous material, such as DANAKLON ES (polypropylene/
polyethylene bicomponent fibres made by Danaklon, Denmark ) .
The microfine fibres are a highly efficient cigarette smoke f iltration medium and function to remove liquid components from the smoke, as described more fully in U. S . Patent no . 3, 882, 877 . The f iltration is 50 efficient that the filter can rapidly become blocked 30 and permits no further smoke filtration to occur.
The latter effect is employed to advantage in the novel cigarette smoke f ilter of the invention, where the cigarette smoke is drawn in the same axial direction as the direction of extension of the cigarette filter 35 ,~ nPnts. As the first few puffs are taken, smoke enters the annulus material and then passes through the 2~4~a~3 microfine fibres into the low resistance smoke flow passage to the smoker ' s mouth . The microf ine f ibres in the area where the smoke is drawn through rapidly become clogged, 60 that the smoke is forced to assume a longer 5 path of travel through the annulus material until it can pass through the microfine fibres into the low resistance smoke path.
As the cigarette is smoked, it is necessary for the cigarette smoke to travel for progressively greater 10 di6tances in the annulus material before it can pass through the microfine fibres. A uniform amount of droplet material i5 removed from the smoke by the microfine fibres along the whole of the length of the filter, since each successive portion of the fibres is 15 able to filter out only the same maximum quantity of droplets. However, by forcing the smoke to assume a progressively longer path of travel through the annulus f ilter material progressively greater quantities of droplets are removed from the smoke aerosol. The result 20 of this filtration operation is that the smoke entering the smoker's mouth has a substantially uniform tar content and the problem of increasing tar yield from the cigarette is compensated for by providing progressively increased filtration of the tobacco smoke before it 25 reaches the smoker's mouth, without introducing an unacceptable level of pressure drop.
Accordingly, in another aspect of the present invention, there is provided a method of achieving a more uniform delivery of tar in tobacco smoke entering a 30 smoker's mouth from a cigarette, characterized by causing the tobacco smoke to pass from a burning cigarette f irst into an outer cylinder of tobacco smoke filter material of higher resistance to smoke flow, and then through an inner cylinder of microfine fibres into 35 an axial flow path to the smoker's mouth of lower resistance to smoke flow, filtering filterable 6 20~9573 materials, including tar, from the smoke both in the outer cylinder and the inner cylinder, and causing said smoke to pass through a progressively longer flow path through said outer cylinder as a progressively increased 5 proportion of the inner cylinder becomes incapable of effecting filtration, thereby to remove progressively greater proportion of filterable materials, including tar, from the tobacco smoke.
The invention is described further, by way of 10 illustration, with reference to the accompanying drawings, in which:
Figure l is a schematic sectional view of a novel cigarette filter constructed in accordance with one embodiment of the invention.
Referring to the drawing, a cylindrical cigarette 10 includes a cigarette rod 12 and a novel filter 14, having a construction which the applicants regard as the current best mode of carrying out the invention. The cigarette rod 12 has a conventional paper wrapper 16 and is joined 20 to the filter 14 by a conventional cork wrap 18.
The filter 14 comprises an outer annulus 20 of conventional cellulose acetate tow material having an outer wrap 22. A cylinder of microfine fibres 24 abuts the inner radial extremity of the annulus 20 and 25 typically is supported between outer layers of low flow resistance fabric.
The cylinder 24 is sandwiched between the annulus 20 and an inner plug 26 of low flow resistance material, such as low flow resistance acetate. The inner plug 26 30 may be omitted entirely, if desired, but preferably is employed to provide mechanicaI strength and stability to the structure. Alternative support structures may be employed, such as an extruded plastic core with a star-shaped cross-section or other convenient shape providing A
7 2~9573 smoke flow channels radially inwardly of the cylinder 24 .
At the end of the filter 14 opposite to the smoking end of the cigarette 10, the f ilter is sealed against 5 the f low of cigarette smoke directly from the cigarette rod 16 to the acetate plug 26, such as by crimping 32 the acetate plug 26, and/or by providing a circular baffle 34 overlying the end of the acetate plug 26.
The provision of such f low directing means ensures 10 that any smoke drawn by the smoker from the cigarette rod 12 enters the outer annulus 20 of acetate tow.
Since the inner plug 26 provides a lower resistance flow path for the cigarette smoke than the higher flow resistance annulus, the cigarette smoke tends to want to 15 flow radially inwardly from the resistance annulus 20 into the acetate plug 26, which results in the smoke passing through the cylinder of fibrous filter material 24 .
The 6moke follows the path of lea6t resistance so 20 that, initially, the smoke flows only for a short distance through the annulus material 20 before flowing through the microfine fibres into the acetate plug 26.
However, the microfine fibres effect efficient f iltration of the tobacco smoke to remove smoke-borne 25 particulates including tar-containing droplets and the fibres eventually are unable to effect further filtration. Accordingly, the microfine fibres in the cylinder 24 become, in the direction towards the smoking end of the cigarette 10, progressively unable to effect 3 0 f i ltration .
The cigarette smoke, therefore, is required to transverse a progressively longer path through the annulus filtration material 20 before the smoke can travel radially inwardly into the acetate plug 26. In 35 this way, a progressively greater degree of filtration is effected by the annulus material 20 and, thereby, a ~ 3 progressively greater degree of overall f iltration is effected as the cigarette 10 is smoked, thereby compensating for the progressively greater tar production by the cigarette rod 12.
In the illustrated f~r~hotl;r--nt, smoke can pass from the annulus materiAl 20 directly into the smoker's mouth. However, the predominant smoke flow path is via the acetate plug 26 because of its lower resistance to smoke flow. In addition, if desired, an annular barrier may be provided overlying the smoking end of the annulus material 20 to force all the smoke to flow to the 6moker's mouth through the acetate plug 26.
The filter element 10 may be formed in any convenient manner. In one embodiment, the acetate plug 26 is replaced by an extruded plastic core having a star-shaped cross section so as to provide a plurality of rhAnnPl c through which the filtered smoke can pass to the smoker. The plastic core then is reciprocated in front of a fine fibre extruder on a continuous basis.
The plastic core is rotated about its axis, so that the fibers are collected in an uniform layer 24 on the periphery of the core i . e., at the radial extremities of the points of the star. The relatively few microfine f ibers which may randomly extend into the air pARsa~Pc between the points of the star-shaped cross section are not sufficient to affect significantly the low pressure drop ducts between the legs of the star.
The continuous rod then i5 passed through a filter-making machine, wherein the core is periodically crimped and the normal high efficiency filter material 20 is placed on the outside of the layer 24 of microfine fibres. The filter then is wrapped in conventional plug wrap 22 and cut at the crimped points to provide a plurality of filter elements 14.
g The present invention provides a novel cigarette filter structure to provide a uniform delivery of tar to a smoker by providing for successively greater degrees of filtration as the cigarette is smoked, without producing unacceptable levels of pressure drop. Cigarettes are a staple item of commerce. Modifications are possible within the scope of this invention.
Claims (8)
1. A cigarette smoke filter element, characterized by an outer elongate cylinder of tobacco smoke filter materials, an inner elongate cylinder of microfine fibres wherein the microfine fibres each has a diameter from about 0.5 to about 10 microns, an axial cigarette smoke path radially inwardly of said cylinder of microfine fibres, said outer cylinder of smoke filter material having a greater resistance to the flow of cigarette smoke therethrough than said axial flow path, and tobacco smoke flow path directing means located at one end of said filter element for directing cigarette smoke from a cigarette to which the filter element is attached, only into said outer cylinder of tobacco smoke filter material.
2. The filter element claimed in claim 1, wherein the cylinder of microfine fibres has a thickness of about 0.05 to about 4 mm and a density of about 0.05 to about 0.3 g/cc.
3. The filter element of claim 2, wherein the outer cylinder of tobacco smoke filter material is conventional cellulose acetate tow filter material.
4. The filter element of claim 3, wherein said deflection means is provided by baffle means at said one end of said filter element.
5. The filter element of claim 3, wherein said axial cigarette smoke path is provided by a low flow resistance acetate material.
6. The filter element of claim 5, wherein said low resistance acetate material is crimped against tobacco smoke flow at said one end of the filter element.
7. The filter element of claim 3, wherein said axial cigarette smoke path is provided by an elongate plastic tube having a star-shaped cross section, whereby a plurality of flow paths is provided radially inwardly of said cylinder of microfine fibres.
8. The filter element of any one of claims 1, 2, 3, 4, 5, 6 or 7 in combination with a cigarette rod in a cigarette, with said tobacco smoke flow path directing means being located adjacent the join of said filter element to said cigarette rod.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB898904752A GB8904752D0 (en) | 1989-03-02 | 1989-03-02 | Uniform tar delivery profile filter |
| GB8904752.6 | 1989-03-02 | ||
| GB8909660.6 | 1989-04-27 | ||
| GB898909660A GB8909660D0 (en) | 1989-04-27 | 1989-04-27 | Uniform tar delivery profile filter-11 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2049573A1 CA2049573A1 (en) | 1991-09-02 |
| CA2049573C true CA2049573C (en) | 1997-01-14 |
Family
ID=26295035
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002049573A Expired - Fee Related CA2049573C (en) | 1989-03-02 | 1990-03-01 | Uniform tar delivery profile filter |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0461162B1 (en) |
| JP (1) | JP2701974B2 (en) |
| AU (1) | AU629320B2 (en) |
| CA (1) | CA2049573C (en) |
| DE (1) | DE69031032T2 (en) |
| WO (1) | WO1990009741A1 (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8823902D0 (en) * | 1988-10-12 | 1988-11-16 | Rothmans Int Tobacco | Cigarette filter rod elements & cigarettes incorporating such filter rod elements |
| US5365951A (en) * | 1990-08-24 | 1994-11-22 | Philip Morris Incorporated | Concentric smoking filter having cellulose acetate tow periphery and carbon-particle-loaded web filter core |
| US5746230A (en) * | 1990-08-24 | 1998-05-05 | Philip Morris Incorporated | Concentric smoking filter having discrete tow and web filter media |
| GB9117118D0 (en) * | 1991-08-08 | 1991-09-25 | Rothmans Benson & Hedges | Control of cigarette smoke chemistry |
| AU699329B2 (en) * | 1991-08-08 | 1998-12-03 | Rothmans International Services Limited | Control of cigarette smoke chemistry |
| GB9122935D0 (en) * | 1991-10-30 | 1991-12-18 | Rothmans Benson & Hedges | Novel cigarette system |
| TR28750A (en) * | 1992-12-18 | 1997-02-28 | Rothmans Benson & Hedges | A new cigarette structure that allows individual cigarettes to be partially smoked, extinguished and then reintroduced. |
| TR26626A (en) * | 1992-12-18 | 1995-03-15 | Rothmans Benson And Hedges Inc | NEW VERY SOFT SMOKING SYSTEM. |
| GB9307710D0 (en) * | 1993-04-14 | 1993-06-02 | Rothmans Benson & Hedges | Smoking apparatus-l |
| DE4322967C1 (en) * | 1993-07-09 | 1994-10-13 | Rhodia Ag Rhone Poulenc | Cellulose acetate filter tow, production thereof and use thereof as tobacco smoke filter element |
| US7987856B2 (en) * | 2005-12-29 | 2011-08-02 | Philip Morris Usa Inc. | Smoking article with bypass channel |
| GB0713905D0 (en) * | 2007-07-17 | 2007-08-29 | British American Tobacco Co | Cellulose acetate thread in filter |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1097748A (en) * | 1965-05-27 | 1968-01-03 | Monsanto Co | Cigarette filter |
| US3502087A (en) * | 1968-07-05 | 1970-03-24 | Ernest J Romano | Cigarette filter |
| US3621851A (en) * | 1969-11-26 | 1971-11-23 | Kata Mfg & Filtering Co | Filter for smoker's article |
| US3854384A (en) * | 1971-05-24 | 1974-12-17 | Brown & Williamson Tobacco | Method of making tobacco smoke filters |
| GB1360611A (en) * | 1971-06-30 | 1974-07-17 | Molins Ltd | Cigarette filters |
| DE3624661A1 (en) * | 1986-07-22 | 1988-02-04 | Rhodia Ag | VENTILATED CIGARETTE |
| GB8823902D0 (en) * | 1988-10-12 | 1988-11-16 | Rothmans Int Tobacco | Cigarette filter rod elements & cigarettes incorporating such filter rod elements |
| DK499289A (en) * | 1988-10-12 | 1990-04-13 | Rothmans Int Tobacco | CANDLE ELEMENTS FOR CIGARET FILTERS AND CIGARETTE EQUIPPED WITH SUCH CUSTOM ELEMENTS |
-
1990
- 1990-03-01 AU AU52689/90A patent/AU629320B2/en not_active Ceased
- 1990-03-01 JP JP2504512A patent/JP2701974B2/en not_active Expired - Lifetime
- 1990-03-01 EP EP90904210A patent/EP0461162B1/en not_active Expired - Lifetime
- 1990-03-01 CA CA002049573A patent/CA2049573C/en not_active Expired - Fee Related
- 1990-03-01 DE DE69031032T patent/DE69031032T2/en not_active Expired - Fee Related
- 1990-03-01 WO PCT/CA1990/000070 patent/WO1990009741A1/en active IP Right Grant
Also Published As
| Publication number | Publication date |
|---|---|
| WO1990009741A1 (en) | 1990-09-07 |
| JP2701974B2 (en) | 1998-01-21 |
| EP0461162A1 (en) | 1991-12-18 |
| EP0461162B1 (en) | 1997-07-09 |
| AU629320B2 (en) | 1992-10-01 |
| JPH04503753A (en) | 1992-07-09 |
| CA2049573A1 (en) | 1991-09-02 |
| AU5268990A (en) | 1990-09-26 |
| DE69031032D1 (en) | 1997-08-14 |
| DE69031032T2 (en) | 1998-01-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |