Smoking article
The invention relates to a smoking article comprising a rod and a filter and to a process of manufacturing such smoking article . Tipping papers are used to connect a filter to a tobacco rod in the manufacture of filter cigarettes. Generally, a tipping paper comprises or even completely consists of paper, but since it may also involve different materials, in the follow¬ ing just the term "tipping" is used.
While in most filter cigarettes the tipping has a straight cut perpendicular to the longitudinal axis of the cigarette, spe¬ cial decorative effects on the cigarette can be obtained by using a curved or patterned cut at the edge of the tipping, i.e. at the rod-sided edge line where the tipping overlaps the tobacco rod.
Before filter cigarettes became popular, non-filter cigarettes had been equipped with a so-called mouthpiece, i.e. a layer of foil, paper or cork to be applied over the cigarette paper. A method for applying a non-straightly cut mouthpiece to obtain an ornamental edge zone is described in GB 252,838 A.
GB 430,240 A discloses the attachment of a filter enclosed in a projecting tube to a cigarette rod. Slits or serrations in the rod-sided end region of the tube facilitate the insertion of the cigarette rod.
In current filter-attaching units, a process different from that disclosed in GB 430,240 A is applied: A double filter having a certain diameter and twice the filter length is placed between two tobacco rods having the substantially same
diameter. A strip of tipping having a width which is greater than the length of the double filter is supplied from a bob¬ bin, cut to a length somewhat greater than the circumference of the double filter and the cigarette rods, glue-coated and wrapped around the double filters and the cigarette rods. Fi¬ nally, the double cigarette made in this way is cut centrally to obtain two single filter cigarettes.
GB 2 199 726 A discloses a tipping paper having a decorative, non-straight rod-sided edge line for the use in making filter cigarettes. Unless the rod-sided edge line (i.e. the cut line) of the tipping comprises linear line segments running perpendicularly to the longitudinal axis of the rod, as in some em¬ bodiments, there will be a mismatch of different regions of the decorative pattern at the seam line of the tipping, which causes a negative impact on the intended decorative effect. WO 03/037112 A describes a tipping having punch-outs or openings in its rod-sided area to enhance diffusion of carbon monoxide out of the cigarette paper. An embodiment having punch-outs at the rod-sided edge line of the tipping is included, which causes a similar mismatch as mentioned before.
Moreover, WO 2012/045468 A discloses cut-out patterns, either within the area or at the rod-sided edge line of a tipping. When such tipping papers are supplied on an endless strip from a bobbin, as described further above, the cut-out patterns pe¬ riodically repeat with a repetition length which is somewhat greater than the circumference of a filter to allow for some overlap in a seam area after the tipping strip has been cut and an individual tipping has been laid around a cigarette. The cut is to extend through a straight line segment (running perpendicularly to the longitudinal axes of filter and ciga¬ rette) of the rod-sided edge line of the tipping. In this case, the resulting cigarettes will exhibit the same tipping pattern at the same position, and there will be no mismatch at
the seam area because the cut-out pattern does not extend to the seam area.
However, when an endless tipping strip is fed from a bobbin into the filter attachment section of a cigarette maker, any means for registration of certain positions on the tipping strip to the position of the cutting means for cutting the strip are only available on machines with a special and expen¬ sive registration kit. Thus, usually the position of any pat- tern or mark on the tipping relative to the cutting line is not determined and will vary over production time. In particu¬ lar, it will occur that the tipping strip is cut at the position of a cut-out element of the pattern. Thus, the cutting line moves from the straight line segment regions disclosed in WO 2012/045468 A into a curved cut-out part in the pattern of the tipping. It is obvious that in this case different regions of the pattern will overlap at the seam line of the tipping, causing a negative visual impression. It is the object of the invention to provide a smoking article comprising a rod and a filter, wherein the tipping for connecting rod and filter can include a cut-out pattern which gives a positive visual impression in the finished smoking ar¬ ticle, without the need for applying particular means in the manufacturing process to register the pattern.
This object is achieved by a smoking article as defined in claim 1. Claim 11 relates to a process of manufacturing such smoking articles. Advantageous embodiments of the invention follow from the dependent claims.
The smoking article according to the invention comprises a rod and a filter, both having generally the same longitudinal axis and generally the same circumference. The rod and the filter are connected by a tipping, which extends about the circumfer-
ence and has a rod-sided edge line provided with a cut-out pattern along the circumference. The pattern is composed of periodically repeating subunits having a subunit length meas¬ ured along the circumference. The ratio of the circumference to the subunit length is a natural number, preferably 1 or 2.
The tipping may comprise an overlap area where it overlaps to itself, i.e. a seam area. If the pattern periodically contin¬ ues at the rod-sided edge line of the overlap area, a matching of the pattern will be achieved at this seam area, even when the pattern does not involve, at least in the seam area, lin¬ ear line segments running perpendicularly to the longitudinal axis (as disclosed in WO 2012/045468 A) . This results from the selection of the subunit length as 1/n of the circumference of rod and filter, n = 1, 2, 3, etc.
The invention creates a special look of the tipping giving the impression of an attractive pattern, without a mismatch in the seam area, e.g. a pattern having an inclined edge, a wave or an angle. There is no need for linear line segments of the pattern running perpendicularly to the longitudinal axis of the cigarette. Two embodiments include either a sinusoidal or a triangular (zigzag) pattern, but the invention is not restricted to those.
In a process of manufacturing smoking articles according to the invention, the tipping is supplied from an endless tipping strip having an endless cut-out pattern along a longitudinal edge. This cut-out pattern is composed of periodically repeat- ing subunits having a subunit length equal to the circumfer¬ ence of the smoking articles divided by a natural number, which preferably is selected as 1 or 2. In the usual manufac¬ turing process, double filters are placed between two tobacco rods and wrapped with a double tipping supplied from an end- less double-width tipping strip, before the double cigarettes
thus produced are cut in the middle of the double filters, as explained further above. In this case both longitudinal edges of the double-width tipping strip can be provided with cut-out patterns composed of periodically repeating subunits fulfill- ing the above criterion related to the ratio of the circumfer¬ ence to the subunit length. There is no need that the patterns at both longitudinal edges are equal.
Moreover, it is an essential benefit of the invention that there is no need to cut a respective tipping (or double tip¬ ping) from the endless tipping strip (or the endless double- width tipping strip) in register with the pattern. Even the length of the cut tipping (or double-tipping) , measured in the direction of the circumference, does not matter because any excessive length will just increase the overlap area without affecting the appearance of the overlap area by a mismatch in the pattern. To achieve all this, it is important that the above criterion related to the ratio of the circumference to the subunit length is met.
Since cigarettes are manufactured in an air-conditioned envi¬ ronment involving humidity control, tolerances concerning the circumference of smoking articles or the length or width of tipping paper are generally small. For example, a typical tol- erance for the circumference of a cigarette filter is 0.1 mm or even less. That means that the above ratio of the circum¬ ference to the subunit length can be determined rather pre¬ cisely, and deviations from a given natural number are corre¬ spondingly small.
In advantageous embodiments of the invention, the tipping overlaps the rod by at most 8 mm. This figure allows the ap¬ plication of a standard smoking analysis even though the dis¬ tance between the rod-sided edge line of the tipping and the rod-sided end of the filter varies. The procedure to estimate
the "butt length" for standard machine-smoking is defined in DIN ISO 4387:2011-01 as being the largest of either 23 mm, filter length + 8 mm, or tipping length + 3 mm. A smoking article according to the invention will have the defined butt length independent of the position where the tipping length is measured if no part of the tipping extends to further than 8 mm upstream from the rod-sided end of the filter.
Moreover, along the pattern a maximum/minimum amplitude (i.e. its maximum total variation) , measured in the direction of the longitudinal axis, may be at most 6.5 mm. To allow a reliable and tight connection between the filter and the rod, a minimum overlap of 1.5 mm is required. This criterion will be ful¬ filled if the maximum/minimum amplitude of the cut-out pattern is 6.5 mm or less, provided the tipping extends far enough (but not necessarily further than 8 mm) upstream from the rod- sided end of the filter.
In further advantageous embodiments of the invention, at least one additional design element having an edge segment is printed onto the tipping, wherein at least part of the edge segment runs in parallel to the cut-out pattern. Thus, the tipping is printed with a specific pattern, e.g. lines or are¬ as, and parts of this printed pattern run in parallel the rod- sided edge line of the tipping as defined by the cut-out pat¬ tern, which may enhance the optical appearance of the smoking article .
The smoking article can be designed as a filter cigarette, in which the rod comprises tobacco-containing material wrapped with a cigarette paper. The tobacco-containing material may be, e.g., a usual tobacco blend or a mixture of tobacco with some flavourant material.
In other embodiments, the rod comprises a hollow tube adapted to be filled with loose tobacco. Such smoking articles, some¬ times called "filter tubes", are used by consumers in order to prepare their own cigarettes from cut tobacco taken from a separate package.
In the following, the invention is further explained by means of embodiments. The figures show in Figure 1 a schematic illustration of a standard method of at¬ taching filters to cigarette rods, which can also be modified for use with the present invention,
Figure 2 a schematic cross sectional view of an embodiment of a filter cigarette taken through the filter,
Figure 3 in parts (a) , (b) and (c) plan views of parts of em¬ bodiments of endless double-width tipping strips, as used with the present invention, and
Figure 4 in parts (a) and (b) views of two embodiments of fil¬ ter cigarettes according to the invention.
In Figure 1, it is schematically illustrated how filters are attached to smoking article rods by means of a current filter- attaching unit. To this end, an endless strip (web) 1 of tip¬ ping material (usually paper) having a width of 2-b is sup¬ plied from a bobbin. A double filter 2, i.e. a piece of filter rod having twice the length of a filter of a finished smoking article, is placed in between two smoking article rods 3, which in the embodiment are tobacco rods comprising a tobacco blend wrapped in cigarette paper. Both the double filter 2 and the rods 3 have a diameter d. To attach the double filter 2 to the rods 3, a piece of material, designated as double tipping 4, is cut from the tipping strip 1, glue-coated and wrapped
around the double filter 2 and the rods 3. The length of the double tipping 4, designated by L in Figure 1 and measured in circumferential direction of the double filter 2 and the rods 3, is somewhat greater than the circumference n-d of the dou- ble filter 2 and the rods 3 so that the double tipping 4 com¬ pletely covers the lateral area of the double filter 2 and al¬ lows for an overlap area along a seam line. Moreover, since 2-b is greater than the length of the double filter 2 measured in the direction of the longitudinal axis of the double filter 2 and the rods 3, the double filter 2 is safely attached to both rods 3. Finally, the double cigarette made in this way is cut centrally, as indicated in Figure 1 by the line c, to ob¬ tain two single filter cigarettes. Figure 2 shows a cross section through a filter cigarette manufactured in this way, in a plane running through the fil¬ ter and perpendicularly to the longitudinal axis of the filter cigarette. The filter is designated by 10, the tipping by 12 and the overlap area by 14. The width of the overlap area 14 is indicated by e. It is L = n-d + e.
The process described so far can be used in the manufacture of conventional smoking articles as well as in the manufacture of smoking articles according to the invention. In the invention, however, the tipping strip 1 of Figure 1, which has straight longitudinal edges, is replaced by a tipping strip in which the respective longitudinal edges are provided with an endless cut-out pattern, which is composed of periodically repeating subunits. Figures 3(a), 3(b) and 3(c) illustrate three embodi- ments, in which the respective double-width tipping strips are designated by 20, 20' and 20", respectively, and the respec¬ tive endless cut-out patterns by 22, 22' and 22", respec¬ tively.
The respective subunits have a length measured in the direc¬ tion indicated by the vertical double arrow in Figure 3 (a) . The subunit length is related to the diameter d of the filter and the rod by subunit length = n-d / n with n being a natural number. In Figure 3(a) is n = 2, and in Figures 3(b) and 3(c) is n = 1.
The patterns 22 and 22' in Figures 3(a) and 3(b), respec¬ tively, are triangular (zigzag-shaped), and the pattern 22" in Figure 3(c) is sinusoidal. The respective maximum/minimum am¬ plitudes are designated by a, a' and a", respectively.
When a tipping cut from one of the tipping strips 20, 20' and 20" is wrapped around the filter and the rod of a smoking ar¬ ticle, the respective cut-out pattern 22, 22' and 22" extends along the circumference of the smoking article and defines the rod-sided edge line of the respective tipping. Because of the above relation subunit length = n-d/n, the pattern fits to the circumference of the smoking article, and there is no mismatch at the overlap area (14 in Figure 2) of the tipping. This holds irrespective of the actual value of L (see Figure 1) or e (see Figure 2) . In other words, the cutting step for preparing double tippings (4 in Figure 1) from an endless double strip (1 in Figure 1; 22, 22', 22" in Figure 3) does not re¬ quire any registration with respect to the cut-out pattern. The width e may even vary during the process.
Endless tipping strips like 20, 20', 22" having a desired cut¬ out pattern like 22, 22', 22" can be prepared from endless tipping strips having straight (plain) edges (like 1 in Figure 1), e.g., by laser-cutting. They can be delivered in a rolled- up state on bobbins, ready for use in a process described in
the context of Figure 1. It is also conceivable that the pat¬ terns at both longitudinal edges of a tipping strip are dif¬ ferent. Moreover, the process is not restricted to the use of double filters and double-width tipping strips, but generally it is also possible to assemble single filters by means of single tippings cut from a single-width tipping strip.
Figures 4 (a) and 4 (b) show embodiments of finished smoking ar¬ ticles, i.e. filter cigarettes 30 and 30'. The filter ciga- rettes 30 and 30' comprise a wrapped tobacco rod 32 and 32', respectively, connected to a filter 34 and 34 ' , respectively, by a tipping 36 and 36', respectively.
The tipping 36 has a rod-sided edge line 37 provided with a zigzag cut-out pattern 38. Moreover, an element 40 having an edge segment 42 is printed onto the tipping 36. The edge seg¬ ment 42 runs in parallel to the edge line of the tipping 36 as defined by the cut-out pattern 38, see Figure 4(a) . In Figure 4(b), a rod-sided edge line 37' is provided with a sinusoidal cut-out pattern 38'. A printed element 40' consists of two lines, one of them designated by 42', which is an edge segment running in parallel to the cut-out pattern 38'.