CA2152161A1 - Cigarette filter rod elements and cigarettes incorporating such filter rod elements - Google Patents
Cigarette filter rod elements and cigarettes incorporating such filter rod elementsInfo
- Publication number
- CA2152161A1 CA2152161A1 CA002152161A CA2152161A CA2152161A1 CA 2152161 A1 CA2152161 A1 CA 2152161A1 CA 002152161 A CA002152161 A CA 002152161A CA 2152161 A CA2152161 A CA 2152161A CA 2152161 A1 CA2152161 A1 CA 2152161A1
- Authority
- CA
- Canada
- Prior art keywords
- cigarette filter
- tube
- adhesive
- filter according
- cigarette
- 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.)
- Abandoned
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
Landscapes
- Cigarettes, Filters, And Manufacturing Of Filters (AREA)
Abstract
Disclosed is a filter element (21) for a cigarette, and a cigarette incorporating such a filter element, comprising an outer wall provided by a plug wrap (4) surrounding an axially extending porous barrier tube (2) of micro-fibres. The space therebetween is called with a porous filtering material (3). A porous support in the form of a rod of filtering material (5) is provided with an adhesive layer in the form of an adhesive tube (1). The core rod, comprising the barrier tube (2), adhesive tube (1), and porous support (5) is crimped to form a crimp (6) impervious for gas flow. The adhesive layer may conveniently be provided by an adhesive material, for example nitrile rubber, vinyl acetate-acrylic acid, vinyl acetate-ethylene, polyacrylate(carboxylic)polyamides, polyimides, polyhydroxy ether, polyester plus isocyanate, or another suitable adhesive. The material WUNDAWEBTM is particularly suitable.
Description
21~2161 CIGARETTE FILTER ROD T~'rT~'M~TS AND CIGARETTES
INCORPORATING SUCH FILTER ROD ~T~M~TS
TECHNICAL FIELD OF THE INVENTION
This invention relates to cigarette filter rod elements and cigarettes incorporating such elements.
BACKGROUND ART
In EP-A-0364253 a cigarette filter rod element is shown having an outer wall which surrounds an axially extending porous barrier tube made from micro-fine fibres to provide a space therebetween which is fiIled with a porous filtering material. One end of the barrier tube is closed and the tube is lcoated so that at least part of the gas flow passes continuously through its wall. In some of the embodiments described the end of the barrier tube is closed by deforming the tube material, for example by crimping. Again, in some embodiments the barrier tube is carried on a porous support. In EP-A-0310257 it has been suggested that a closure of a tube in a filter may be made by application of sufficient glue or other iller material.
DISCLOSURE OF THE INVENTION
It has been found that there are difficulties in crimping the closed end due to the properties of the material and if a porous support is employed the material of the barrier tube and the porous support may be incompatible for self-adhesion with heat and tend not to stick together satisfactorily after crimping under heat and pressure.
The present invention is intended to overcome or at least alleviate the difficultie.s referred to above.
The present invention provides a cigarette filter rod element comprising an axially extending porous AMENDEDS~
21~2161 . .
~ barrier tube enclosing a porous filtering material, one end of said barrier tube being closed by deforming the tube material, the tube being located so that at least part of the gas flow through the filter passes continuously through a wall thereof;
is characterized in that an adhesive in the deformed part holds it together at its closed end and is provided by a layer of adhesive at the inner surface of the barrier tube.
Preferably, the barrier tube is surrounded by an outer wall to define a space therebetween which is at least partly filled with a porous filtering material.
The adhesive layer may conveniently be provided by an adhesive material, for example nitrile rubber, vinyl acetate-acrylic acid, vinyl acetate-ethylene, polyacrylate (carboxylic) polyamides, polyimides, polyhydroxy ether, polyester plus isocyanate or any other suitable adhesive. It may be a layer separate from or on the surface of the barrier layer, but in either case will preferably be coextensive with that layer.
It has been found that the material sold under the Trade Mark "WUNDAWEB" made by Frudenberg Nonwovens Ltd of Halifax, England, is particularly suitable to provide the adhesive layer.
Preferably the barrier tube is made of micro-fine fibres, a suitable diameter of which is between 0.1 ~m and 10 ~m. Layers of micro-fine fibres in the barrier tube can have one or more layers of protective fabric made up of coarse fibres and the protective fabric can be porous. Advantageously, these micro-fine fibres and the protective fabric may be composed of organic polymeric materials, for example polypropyiene f_bres.
The wall thickness of the barrier tube can be A~iDE0 SHE~
between 0.05 mm and 2 mm with a density of between 0.04 and 0.3 gcm~3.
Preferably the barrier tube is carried on a porous support and this can be made as a rod of filter material.
The porous support rod can be made of a filter material which has a low flow resistance and a low filtration efficiency and the filter material surrounding the barrier tube can have a higher flow resistance.
In a convenient construction the end of the barrier tube is closed by crimping.
Tip ventilation holes can be provided if desired.
The invention also includes a cigarette filter rod element which comprises a first rod segment formed as an element as set forth above and a second filter rod segment in abutment therewith.
The second filter rod segment may comprise an impervious material or a aensely packed filter material with a high resistance to gas flow and a centrally and axially situated core of lower resistance to gas flow.
The invention also includes a cigarette incorporating a filter rod element as set forth above.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention can be performed in various ways and some embodiments will now be described by way of example and with reference to the accompanying drawings in which:-Figure l is a cross-sectional view of one embodiment of a filter rod element according to the invention;
Figure 2 is a cross-sectional view on line II-II
of Figure l;
Figure 3 is a cross-sectional view on line III-III of Figure l;
Figure 4 is a cross-sectional view of another embodiment of a filter rod element according to the invention;
Figure 5 is a cross-sectional view on line V-V of Figure 4;
Figure 6 is a cross-sectional view of another embodiment of the filter rod element according to the invention;
Figure 7 is a cross-sectional view on line VII-VII of Figure 6;
Figure 8 is a cross-sectional view of another embodiment of a filter rod element according to the invention;
Figure 9 is a cross-sectional view on line IX-IX
of Figure 8;
Figure lO is a cross-sectional view of yet another embodiment of a filter rod element according to the invention;
Figure ll is a cross-sectional view on line XI-XI
of Figure lO;
Figure 12 is a cross-sectional view of a still further embodiment of a filter rod element according to the invention;
Figure 13 is the end view of the filter rod element as viewed from filter end 29 as shown in Figure 12;
Figure 14 is the end view of the filter rod element as viewed from filter end 28 as shown in Figure WO94/14345 215 2161 PCT/GB931026~
12;
Figure 15 is a cross-sectional view of the embodiment shown in Figure 1, showing the smoke flow directions inside the filter rod element during the initial smoking periodi Figure 16 is a cross-sectional view of the embodiment as shown in Figure 1, showing the smoke flow directions inside the filter rod element during the later smoking period;
Figure 17 is a cross-sectional view of the preferred embodiment of a cigarette according to the present invention;
Figure 18 is a diagram showing a process for manufacturing filter rods according to the invention; and Figure 19 shows an alternative process.
BEST MODE ~ON1~PLATED BY THE APPLICANT
As shown in Figures 1, 2 and 3 a filter element 21, according to the invention, comprises an outer wall provided by a plug wrap 4 which surrounds an axially extending porous barrier tube 2 made from micro-fine fibres to provide a space therebetween which is filled with a porous filtering material 3. A porous support in the form of a rod of filtering material 5 is provided with an adhesive layer in the form of an adhesive tube 1.
The core rod provided by the barrier tube 2, adhesive tube 1 and porous support 5 is crimped to form a crimp 6 at what will be referred to as the filter end 8 of the element.
AS will be seen from Figure 3 the crimp 6 is of cruciform shape although other practical shapes can also be used. The crimp 6 is impervious for gas flow.
3S The barrier tube 2 is made of at least one layer WO94/14345 PCT/GB93/026~
of micro-fine fibres which can be produced by a melt-blown process. The diameter of the micro-fine fibres ranges from between 0.1 ~m and 10 ~m. The thickness of this layer ranges between 0.05 mm and 2 mm and the density of the layer ranges from between 0.04 and 0.3 gcm~3. For easier handling and protection the layer of micro-fine fibres can be supplied with either one or two layers of protective fabric made up of coarse fibres. In the case when two protective fabrics are used, the fine fibre layer is sandwiched between these protective fibres which are porous.
The adhesive tube 1 is located between the barrier tube 2 and the filter material 5 and is made of an adhesive material, preferably a hot melt material.
Common adhesive materials such as nitrile rubber, vinyl acetate-acrylic acid, vinyl acetate-ethylene, polyacrylate (carboxylic) polyamides, polyimides, polyhydroxy ether, polyester plus isocyanate, or similar materials are suitable. ~
The function of the adhesive tube is that it helps to_fuse the barrier tube 2 and the material 5 together firmly in the crimp 6 after the crimping process. It will be appreciated that the adhesive tube must be porous to gas flow.
Filter materials 3 and 5 are common cigarette filter materials such as cellulose acetate tow, polypropylene tow, paper, etc. Material 5 is the filter tow item such as 8Y/14000, 6Y/17000 etc, that provides low flow resistance and low filtration efficiency. In comparison, material 3 always provides higher flow resistance than the flow resistance from material 5.
soth materials 3 and 5 may be processed in the presence ?I521 61 of steam. By using a conventional device such as mandrel and steam, material 3 may be moulded so that material 3 does not fill the space 7 where crimp 6 is located.
However, the filter is also effective when the space 7 is filled, as shown in another embodiment of the present invention illustrated in Figures 4 and 5.
Figures 6 and 7 show another embodiment of a filter rod element according to the present invention.
Filter rod element 23 consists of all the parts as shown in Figure 1, except that there are apertures 11 on tubes 1 and 2. The total number of apertures 11 ranges between 1 and 10, preferably 2. The total opening area of the apertures ranges between 0.1 mm2 and 10 mm2. The apertures may be located anywhere between locations K and N so that:
M < ~ L
where M is the distance of the apertures as measured from the filter end 8, and L is the total length of the filter rod element 23.
Figures 8 and 9 show another embodiment in which the filter rod element 24 is a dual filter rod consisting of a plugwrap 12 and filter rod segments 21 and 25.
Filter rod segment 21 is as described in Figure 1.
Filter rod segment 25 consists of a plugwrap 4, and filter material 13. Material 13 is common filter material such as cellulose acetate tow, or polypropylene tow, paper, or similar material. Filter element 24 will also be effective if filter rod element 21 is replaced by filter rod component such as filter rod ~lements 22 or 23.
A~N~,DS~E~
Figures 10 and 11 show yet another embodiment of the filter rod element according to the present invention and in which element 25 is a dual filter rod. It consists of a plugwrap 12 and filter rod segments 21 and 28 Filter rod element 21 is as described in Figure 1.
Filter rod segment 28 consists of a plugwrap 4 and filter materials 15 and 16. Filter materials 15 and 16 are common cigarette filter materials such as cellulose acetate tow, polypropylene tow, paper, etc. Preferably, the material 15 is one that provides a high resistance flow path, and material 16 provides a low resistance flow path. The filter rod element 25 will also be effective if filter rod element 21 is replaced by other elements such as filter rod elements 22 or 23.
Figure 12 shows a still further embodiment of the present invention, being a filter rod element 26 crimped at filter end 8. The filter rod element 26 consists of conventional filter material 5, preferably a cellulose acetate tow such as 8Y/38000 tow. Barrier tube 1 acts as the plugwrap of filter rod element 26. Adhesive tube 2 is located between the barrier tube 1 and the filter material 5. Adhesive tube 2 helps to fuse the barrier tube 1 and material 5 together in crimp 6 after the 25 crimping process. Apertures 11 are shown on the barrier tube 1 and adhesive tube 2, but are optional. Filter rod element 26 can be used to form a filter-tipped cigarette 36 (Fig. 17), with crimp 6 preferably placed to abut the tobacco rod 37 As shown in Figure 14, the crimp 6 has a cruciform section, but other profiles are possible as previously described.
3 5 The flow pattern of smoke through filter rod rl~n~ S~
WO94/1~45 21 5 21 61 PCT/GB93/026~
element according to the invention, without ventilating air, is shown in Figures 15 and 16. Smoke is shown to flow from filter end 8 towards filter end 9. Figure 15 shows the flow paths of the tobacco smoke during the initial puffing period. Before the smoke passes through the filter, the various filter materials are clean.
There are two paths: paths 31 and 32. Flow path 31 is for smoke that flows through the annulus space passage filled with material 3 and path 32 is for smoke that flows through the core rod material 5. Since material 3 always provides higher flow resistance than that from material 5, the amount of smoke on path 31 is lower or even negligible as compared with the amount of smoke on path 32.
The majority of the smoke flows through the region where the resistance is lowest, i.e. region 40.
This smoke has to pass through the micro-fine fabric layer 2 and adhesive layer 1 before reaching material 5.
Figure 16 shows the flow paths inside the filter after a number of puffs of cigarette smoke have passed through~the filter. Region 40 has now collected sufficient ~'tar" from the smoke on the micro-fine fabric such that the flow resistance in region 40 is greatly increased. Consequently the smoke switches to flow through the cleaner fabric surface away from region 40.
Due to flow resistance differences between materials 3 and 5, the amount of smoke flowing in path 31 is again lower or even negligible as compared with the amount of smoke flowing in path 32.
The location B shown in Figures 15 and 16 represents the position of ventilating air flow into filter rod element 21 through ventilation holes on the tipping paper (not shown) and porous plugwrap 4 or through holes formed by a laser.
Figure 17 shows the preferred embodiment o a cigarette according to the present invention. Cigarette ~6 consists of a tobacco rod ~7, a filter rod element 21 and tipping paper 17 and ventilation holes 18. The cigarette also performs effectively if filter rod element 21 is replaced by other filter rod elements such as element 22, 23, 24 or 25. Filter end 8 is shown preferably in abutment with the tobacco rod. However, the filter is also effective if filter end 9 is in abutment with the tobacco rod 37. Cigarette ~6 performs also effectively, with or without the ventilation holes 18.
In the arrangements described above the adhesive material is shown as a tube but it will be appreciated that it could be provided merely as an adhered layer to the barrier tube 2 and could, for example, be formed by spraying an adhesive material onto the rlaterial from which the barrier tube is made. Other ways of providing the layer will be apparent to the man skilled in the art.
Figure 18 is a diagram showing a process for manufacturing filter rods according to the invention and the various features are identified. It will be seen that the porous support, in the form of a rod of filtering material, is made from tow indicated by reference numeral i00 and passes through a tow blooming section 101 and a plasticiser applicator 102. It is then forwarded by a transport jet 103 to a garniture (with steam) 104. The formed rod 105 passes irto a further garniture (with hot air) 106 where it is joined by the micro-flne fabric and an adhesive web indicated by Yi~ S,i~
WO94/14345 215 2161 PCT/GB93l02613 reference numeral 107. The material 107 is supplied to the garniture 106 and is wrapped around the porous support rod 105. The combined material 108 now passes to a heated crimper 109 where it is crimped under heat and pressure into appropriate lengths. The crimped material 110 passes through a transport jet 111 where it is joined by further tow material taken from a tow bale 112 via a booming section 113 and a plasticiser applicator 114.
The wrapped core rod provided by the barrier tube, adhesive layer and porous support, is now wrapped with a plug wrap taken from a reel 115 in a garniture with steam indicated by reference numeral 116.
In an alternative process, as indicated in Figure 19, the same reference numerals are used to indicate similar parts but in this process the adhesive web is indicated by reference numeral 117 is supplied separately from the micro-fine fabric indicated by reference numeral 118. The adhesive web and micro-fine fabric are combined with the porous support rod 105 in the garniture 106.
INCORPORATING SUCH FILTER ROD ~T~M~TS
TECHNICAL FIELD OF THE INVENTION
This invention relates to cigarette filter rod elements and cigarettes incorporating such elements.
BACKGROUND ART
In EP-A-0364253 a cigarette filter rod element is shown having an outer wall which surrounds an axially extending porous barrier tube made from micro-fine fibres to provide a space therebetween which is fiIled with a porous filtering material. One end of the barrier tube is closed and the tube is lcoated so that at least part of the gas flow passes continuously through its wall. In some of the embodiments described the end of the barrier tube is closed by deforming the tube material, for example by crimping. Again, in some embodiments the barrier tube is carried on a porous support. In EP-A-0310257 it has been suggested that a closure of a tube in a filter may be made by application of sufficient glue or other iller material.
DISCLOSURE OF THE INVENTION
It has been found that there are difficulties in crimping the closed end due to the properties of the material and if a porous support is employed the material of the barrier tube and the porous support may be incompatible for self-adhesion with heat and tend not to stick together satisfactorily after crimping under heat and pressure.
The present invention is intended to overcome or at least alleviate the difficultie.s referred to above.
The present invention provides a cigarette filter rod element comprising an axially extending porous AMENDEDS~
21~2161 . .
~ barrier tube enclosing a porous filtering material, one end of said barrier tube being closed by deforming the tube material, the tube being located so that at least part of the gas flow through the filter passes continuously through a wall thereof;
is characterized in that an adhesive in the deformed part holds it together at its closed end and is provided by a layer of adhesive at the inner surface of the barrier tube.
Preferably, the barrier tube is surrounded by an outer wall to define a space therebetween which is at least partly filled with a porous filtering material.
The adhesive layer may conveniently be provided by an adhesive material, for example nitrile rubber, vinyl acetate-acrylic acid, vinyl acetate-ethylene, polyacrylate (carboxylic) polyamides, polyimides, polyhydroxy ether, polyester plus isocyanate or any other suitable adhesive. It may be a layer separate from or on the surface of the barrier layer, but in either case will preferably be coextensive with that layer.
It has been found that the material sold under the Trade Mark "WUNDAWEB" made by Frudenberg Nonwovens Ltd of Halifax, England, is particularly suitable to provide the adhesive layer.
Preferably the barrier tube is made of micro-fine fibres, a suitable diameter of which is between 0.1 ~m and 10 ~m. Layers of micro-fine fibres in the barrier tube can have one or more layers of protective fabric made up of coarse fibres and the protective fabric can be porous. Advantageously, these micro-fine fibres and the protective fabric may be composed of organic polymeric materials, for example polypropyiene f_bres.
The wall thickness of the barrier tube can be A~iDE0 SHE~
between 0.05 mm and 2 mm with a density of between 0.04 and 0.3 gcm~3.
Preferably the barrier tube is carried on a porous support and this can be made as a rod of filter material.
The porous support rod can be made of a filter material which has a low flow resistance and a low filtration efficiency and the filter material surrounding the barrier tube can have a higher flow resistance.
In a convenient construction the end of the barrier tube is closed by crimping.
Tip ventilation holes can be provided if desired.
The invention also includes a cigarette filter rod element which comprises a first rod segment formed as an element as set forth above and a second filter rod segment in abutment therewith.
The second filter rod segment may comprise an impervious material or a aensely packed filter material with a high resistance to gas flow and a centrally and axially situated core of lower resistance to gas flow.
The invention also includes a cigarette incorporating a filter rod element as set forth above.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention can be performed in various ways and some embodiments will now be described by way of example and with reference to the accompanying drawings in which:-Figure l is a cross-sectional view of one embodiment of a filter rod element according to the invention;
Figure 2 is a cross-sectional view on line II-II
of Figure l;
Figure 3 is a cross-sectional view on line III-III of Figure l;
Figure 4 is a cross-sectional view of another embodiment of a filter rod element according to the invention;
Figure 5 is a cross-sectional view on line V-V of Figure 4;
Figure 6 is a cross-sectional view of another embodiment of the filter rod element according to the invention;
Figure 7 is a cross-sectional view on line VII-VII of Figure 6;
Figure 8 is a cross-sectional view of another embodiment of a filter rod element according to the invention;
Figure 9 is a cross-sectional view on line IX-IX
of Figure 8;
Figure lO is a cross-sectional view of yet another embodiment of a filter rod element according to the invention;
Figure ll is a cross-sectional view on line XI-XI
of Figure lO;
Figure 12 is a cross-sectional view of a still further embodiment of a filter rod element according to the invention;
Figure 13 is the end view of the filter rod element as viewed from filter end 29 as shown in Figure 12;
Figure 14 is the end view of the filter rod element as viewed from filter end 28 as shown in Figure WO94/14345 215 2161 PCT/GB931026~
12;
Figure 15 is a cross-sectional view of the embodiment shown in Figure 1, showing the smoke flow directions inside the filter rod element during the initial smoking periodi Figure 16 is a cross-sectional view of the embodiment as shown in Figure 1, showing the smoke flow directions inside the filter rod element during the later smoking period;
Figure 17 is a cross-sectional view of the preferred embodiment of a cigarette according to the present invention;
Figure 18 is a diagram showing a process for manufacturing filter rods according to the invention; and Figure 19 shows an alternative process.
BEST MODE ~ON1~PLATED BY THE APPLICANT
As shown in Figures 1, 2 and 3 a filter element 21, according to the invention, comprises an outer wall provided by a plug wrap 4 which surrounds an axially extending porous barrier tube 2 made from micro-fine fibres to provide a space therebetween which is filled with a porous filtering material 3. A porous support in the form of a rod of filtering material 5 is provided with an adhesive layer in the form of an adhesive tube 1.
The core rod provided by the barrier tube 2, adhesive tube 1 and porous support 5 is crimped to form a crimp 6 at what will be referred to as the filter end 8 of the element.
AS will be seen from Figure 3 the crimp 6 is of cruciform shape although other practical shapes can also be used. The crimp 6 is impervious for gas flow.
3S The barrier tube 2 is made of at least one layer WO94/14345 PCT/GB93/026~
of micro-fine fibres which can be produced by a melt-blown process. The diameter of the micro-fine fibres ranges from between 0.1 ~m and 10 ~m. The thickness of this layer ranges between 0.05 mm and 2 mm and the density of the layer ranges from between 0.04 and 0.3 gcm~3. For easier handling and protection the layer of micro-fine fibres can be supplied with either one or two layers of protective fabric made up of coarse fibres. In the case when two protective fabrics are used, the fine fibre layer is sandwiched between these protective fibres which are porous.
The adhesive tube 1 is located between the barrier tube 2 and the filter material 5 and is made of an adhesive material, preferably a hot melt material.
Common adhesive materials such as nitrile rubber, vinyl acetate-acrylic acid, vinyl acetate-ethylene, polyacrylate (carboxylic) polyamides, polyimides, polyhydroxy ether, polyester plus isocyanate, or similar materials are suitable. ~
The function of the adhesive tube is that it helps to_fuse the barrier tube 2 and the material 5 together firmly in the crimp 6 after the crimping process. It will be appreciated that the adhesive tube must be porous to gas flow.
Filter materials 3 and 5 are common cigarette filter materials such as cellulose acetate tow, polypropylene tow, paper, etc. Material 5 is the filter tow item such as 8Y/14000, 6Y/17000 etc, that provides low flow resistance and low filtration efficiency. In comparison, material 3 always provides higher flow resistance than the flow resistance from material 5.
soth materials 3 and 5 may be processed in the presence ?I521 61 of steam. By using a conventional device such as mandrel and steam, material 3 may be moulded so that material 3 does not fill the space 7 where crimp 6 is located.
However, the filter is also effective when the space 7 is filled, as shown in another embodiment of the present invention illustrated in Figures 4 and 5.
Figures 6 and 7 show another embodiment of a filter rod element according to the present invention.
Filter rod element 23 consists of all the parts as shown in Figure 1, except that there are apertures 11 on tubes 1 and 2. The total number of apertures 11 ranges between 1 and 10, preferably 2. The total opening area of the apertures ranges between 0.1 mm2 and 10 mm2. The apertures may be located anywhere between locations K and N so that:
M < ~ L
where M is the distance of the apertures as measured from the filter end 8, and L is the total length of the filter rod element 23.
Figures 8 and 9 show another embodiment in which the filter rod element 24 is a dual filter rod consisting of a plugwrap 12 and filter rod segments 21 and 25.
Filter rod segment 21 is as described in Figure 1.
Filter rod segment 25 consists of a plugwrap 4, and filter material 13. Material 13 is common filter material such as cellulose acetate tow, or polypropylene tow, paper, or similar material. Filter element 24 will also be effective if filter rod element 21 is replaced by filter rod component such as filter rod ~lements 22 or 23.
A~N~,DS~E~
Figures 10 and 11 show yet another embodiment of the filter rod element according to the present invention and in which element 25 is a dual filter rod. It consists of a plugwrap 12 and filter rod segments 21 and 28 Filter rod element 21 is as described in Figure 1.
Filter rod segment 28 consists of a plugwrap 4 and filter materials 15 and 16. Filter materials 15 and 16 are common cigarette filter materials such as cellulose acetate tow, polypropylene tow, paper, etc. Preferably, the material 15 is one that provides a high resistance flow path, and material 16 provides a low resistance flow path. The filter rod element 25 will also be effective if filter rod element 21 is replaced by other elements such as filter rod elements 22 or 23.
Figure 12 shows a still further embodiment of the present invention, being a filter rod element 26 crimped at filter end 8. The filter rod element 26 consists of conventional filter material 5, preferably a cellulose acetate tow such as 8Y/38000 tow. Barrier tube 1 acts as the plugwrap of filter rod element 26. Adhesive tube 2 is located between the barrier tube 1 and the filter material 5. Adhesive tube 2 helps to fuse the barrier tube 1 and material 5 together in crimp 6 after the 25 crimping process. Apertures 11 are shown on the barrier tube 1 and adhesive tube 2, but are optional. Filter rod element 26 can be used to form a filter-tipped cigarette 36 (Fig. 17), with crimp 6 preferably placed to abut the tobacco rod 37 As shown in Figure 14, the crimp 6 has a cruciform section, but other profiles are possible as previously described.
3 5 The flow pattern of smoke through filter rod rl~n~ S~
WO94/1~45 21 5 21 61 PCT/GB93/026~
element according to the invention, without ventilating air, is shown in Figures 15 and 16. Smoke is shown to flow from filter end 8 towards filter end 9. Figure 15 shows the flow paths of the tobacco smoke during the initial puffing period. Before the smoke passes through the filter, the various filter materials are clean.
There are two paths: paths 31 and 32. Flow path 31 is for smoke that flows through the annulus space passage filled with material 3 and path 32 is for smoke that flows through the core rod material 5. Since material 3 always provides higher flow resistance than that from material 5, the amount of smoke on path 31 is lower or even negligible as compared with the amount of smoke on path 32.
The majority of the smoke flows through the region where the resistance is lowest, i.e. region 40.
This smoke has to pass through the micro-fine fabric layer 2 and adhesive layer 1 before reaching material 5.
Figure 16 shows the flow paths inside the filter after a number of puffs of cigarette smoke have passed through~the filter. Region 40 has now collected sufficient ~'tar" from the smoke on the micro-fine fabric such that the flow resistance in region 40 is greatly increased. Consequently the smoke switches to flow through the cleaner fabric surface away from region 40.
Due to flow resistance differences between materials 3 and 5, the amount of smoke flowing in path 31 is again lower or even negligible as compared with the amount of smoke flowing in path 32.
The location B shown in Figures 15 and 16 represents the position of ventilating air flow into filter rod element 21 through ventilation holes on the tipping paper (not shown) and porous plugwrap 4 or through holes formed by a laser.
Figure 17 shows the preferred embodiment o a cigarette according to the present invention. Cigarette ~6 consists of a tobacco rod ~7, a filter rod element 21 and tipping paper 17 and ventilation holes 18. The cigarette also performs effectively if filter rod element 21 is replaced by other filter rod elements such as element 22, 23, 24 or 25. Filter end 8 is shown preferably in abutment with the tobacco rod. However, the filter is also effective if filter end 9 is in abutment with the tobacco rod 37. Cigarette ~6 performs also effectively, with or without the ventilation holes 18.
In the arrangements described above the adhesive material is shown as a tube but it will be appreciated that it could be provided merely as an adhered layer to the barrier tube 2 and could, for example, be formed by spraying an adhesive material onto the rlaterial from which the barrier tube is made. Other ways of providing the layer will be apparent to the man skilled in the art.
Figure 18 is a diagram showing a process for manufacturing filter rods according to the invention and the various features are identified. It will be seen that the porous support, in the form of a rod of filtering material, is made from tow indicated by reference numeral i00 and passes through a tow blooming section 101 and a plasticiser applicator 102. It is then forwarded by a transport jet 103 to a garniture (with steam) 104. The formed rod 105 passes irto a further garniture (with hot air) 106 where it is joined by the micro-flne fabric and an adhesive web indicated by Yi~ S,i~
WO94/14345 215 2161 PCT/GB93l02613 reference numeral 107. The material 107 is supplied to the garniture 106 and is wrapped around the porous support rod 105. The combined material 108 now passes to a heated crimper 109 where it is crimped under heat and pressure into appropriate lengths. The crimped material 110 passes through a transport jet 111 where it is joined by further tow material taken from a tow bale 112 via a booming section 113 and a plasticiser applicator 114.
The wrapped core rod provided by the barrier tube, adhesive layer and porous support, is now wrapped with a plug wrap taken from a reel 115 in a garniture with steam indicated by reference numeral 116.
In an alternative process, as indicated in Figure 19, the same reference numerals are used to indicate similar parts but in this process the adhesive web is indicated by reference numeral 117 is supplied separately from the micro-fine fabric indicated by reference numeral 118. The adhesive web and micro-fine fabric are combined with the porous support rod 105 in the garniture 106.
Claims (16)
1. A cigarette filter (21-26) comprising an axially extending porous barrier tube (2) enclosing a porous filtering material (5), one end of said barrier tube (6) being closed by deforming the tube material, the tube being located so that at least part of the gas flow through the filter passes continuously through a wall thereof;
wherein an adhesive in the deformed part holds it together at its closed end and is provided by a layer (1) of adhesive at the inner surface of the barrier tube (2).
wherein an adhesive in the deformed part holds it together at its closed end and is provided by a layer (1) of adhesive at the inner surface of the barrier tube (2).
2. A cigarette filter according to claim 1 wherein the barrier tube is surrounded by an outer wall (4) thereby to define a space therebetween which is at least partly filled with a porous filtering material (3).
3. A cigarette filter according to claim 2 wherein the filter material (5) within the barrier tube (2) has a relatively low flow resistance and a relatively low filtration efficiency, and the filter material (3) surrounding the barrier tube (2) has a relatively higher flow resistance.
4. A cigarette filter according to claim 1, claim 2 or claim 3 wherein the adhesive layer is provided by an adhesive material selected from nitrile rubber, vinyl acetate-acrylic acid, vinyl acetate-ethylene, a polyacrylate polyamide, a polyimide, polyhydroxy ether, or polyester and isocyanate.
5. A cigarette filter according to any preceding claim wherein the barrier tube is made of micro-fine fibres.
6. A cigarette filter according to claim 5 wherein the micro-fine fibres have a diameter between 0.1 µm and 10 µm.
7. A cigarette filter according to claim 6 wherein the micro-fine fibres are composed of an organic polymeric material.
8. A cigarette filter according to claim 7 wherein the micro-fine fibres are polypropylene fibres.
9. A cigarette filter according to any preceding claim wherein the wall thickness of the barrier tube is between 0.5 mm and 2 mm.
10. A cigarette filter according to any preceding claim wherein the density of the barrier tube wall is between 0.04 and 0.3 gcm-3.
11. A cigarette filter according to any preceding claim having tip ventilation holes (11) in the barrier tube.
12. A cigarette filter according to any one of the preceding claims wherein the adhesive layer is separate from the barrier layer.
13. A cigarette filter according to any one of claims 1 to 11 wherein the adhesive layer is on the inner surface of the barrier layer.
14. A cigarette filter according to any one of the preceding claims wherein the adhesive layer is coextensive with the barrier layer.
15. A cigarette filter element comprising a first filter segment (21-26) according to any preceding claim and a second filter segment (28) in longitudinal abutment therewith.
16. A cigarette (36) incorporating a filter rod element (21-26) according to any preceding claim.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9226940.6 | 1992-12-24 | ||
| GB929226940A GB9226940D0 (en) | 1992-12-24 | 1992-12-24 | Cigarette filter rod elements and cigarettes incorporating such filter rod elements |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2152161A1 true CA2152161A1 (en) | 1994-07-07 |
Family
ID=10727207
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002152161A Abandoned CA2152161A1 (en) | 1992-12-24 | 1993-12-21 | Cigarette filter rod elements and cigarettes incorporating such filter rod elements |
Country Status (7)
| Country | Link |
|---|---|
| AU (1) | AU5708594A (en) |
| CA (1) | CA2152161A1 (en) |
| FI (1) | FI953129A (en) |
| GB (1) | GB9226940D0 (en) |
| NO (1) | NO952477L (en) |
| WO (1) | WO1994014345A1 (en) |
| ZA (1) | ZA939676B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995035042A1 (en) * | 1994-06-17 | 1995-12-28 | Rothmans International Services Limited | Cigarette filter rod elements and cigarettes incorporating such filter rod elements |
| GB0813567D0 (en) * | 2008-07-24 | 2008-09-03 | British American Tobacco Co | Filter for a smoking article |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8721876D0 (en) * | 1987-09-17 | 1987-10-21 | Rothmans Int Tobacco | Cigarette filter |
| GB8823902D0 (en) * | 1988-10-12 | 1988-11-16 | Rothmans Int Tobacco | Cigarette filter rod elements & cigarettes incorporating such filter rod elements |
| GB8916137D0 (en) * | 1989-07-14 | 1989-08-31 | Rothmans Int Tobacco | Cigarettes |
| GB9008887D0 (en) * | 1990-04-20 | 1990-06-20 | Rothmans Benson & Hedges | Cigarette smoke filter |
-
1992
- 1992-12-24 GB GB929226940A patent/GB9226940D0/en active Pending
-
1993
- 1993-12-21 WO PCT/GB1993/002613 patent/WO1994014345A1/en active Application Filing
- 1993-12-21 CA CA002152161A patent/CA2152161A1/en not_active Abandoned
- 1993-12-21 AU AU57085/94A patent/AU5708594A/en not_active Abandoned
- 1993-12-23 ZA ZA939676A patent/ZA939676B/en unknown
-
1995
- 1995-06-21 NO NO952477A patent/NO952477L/en unknown
- 1995-06-22 FI FI953129A patent/FI953129A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| WO1994014345A1 (en) | 1994-07-07 |
| NO952477D0 (en) | 1995-06-21 |
| ZA939676B (en) | 1994-08-26 |
| AU5708594A (en) | 1994-07-19 |
| FI953129A0 (en) | 1995-06-22 |
| NO952477L (en) | 1995-06-21 |
| GB9226940D0 (en) | 1993-02-17 |
| FI953129A (en) | 1995-06-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |