CN101820782B - Smoking article - Google Patents

Abstract

A smoking article 20 has a pattern 34a, 34b, 34c, 34d, 36d' of permeability reducing film forming compound applied to the wrapping paper 24. The pattern is configured so that when a smoking article is placed on a substrate, at least two longitudinal locations along the length of the tobacco rod have film forming compound located only on sides of the smoking article not in contact with the substrate. At these longitudinal locations, the restricted airflow to the tobacco due to the presence of the substrate, in combination with the film-forming compound located at the sides is sufficient to cause the smoking article to self-extinguish. However, when the smoking article is held by a smoker, the presence of the film-forming compound does not by itself cause the smoking article to extinguish. A desirable self burn capability is therefore maintained.

Description

smoking products

technical field

In general, the present invention relates to a smoking article; more particularly, the present invention relates to a smoking article having a pattern provided on a wrapper for a smoking article while burning. The smoking article reduces the propensity to ignite of the smoking article when it is left unnoticed on the litter. the

Contents of the invention

A smoking article comprises a tobacco rod with a wrapper formed from a base paper web having a nominal porosity. Preferably, zones of add-on material are applied to said base paper web in a pattern comprising a plurality of circumferentially spaced zones spaced longitudinally along said tobacco rod. Each region preferably includes at least two substantially opposing regions of add-on material having a lower than nominal air permeability. Preferably, the areas of add-on material are of sufficient size, shape, and concentration of add-on material such that when the tobacco rod is smoldering and placed on a litter, the tobacco rod will tend to extinguish at the corresponding area. For each consecutive first, second and third region, the zones in the second zone are circumferentially offset relative to the zones in the first zone. Furthermore, the zones in the third region are each circumferentially offset relative to the zones in the first and second regions. the

Preferably, said pattern extends substantially continuously along said tobacco rod such that when said tobacco rod is placed on a support and viewed from one end, at least one region is positioned such that its zone of additional material lies substantially on said tobacco rod. side of the strip. the

Preferably, the smoking article exhibits an ignition propensity of no greater than about 25% and a self-extinguishing value of no greater than 50%. the

Preferably, smoking articles according to the present invention comprise a wrapper having a pattern formed from a film-forming compound that reduces air permeability. The pattern is selected such that when the smoking article is placed on the litter, the smoking article will self-extinguish when the advancing burn line reaches one or more longitudinal positions Where there is film-forming mixture on the sides of the smoking article not in contact with the substrate; but when the smoking article is held by a smoker, these sides with film-forming mixture or film-forming agent The smoking article will not be self-extinguishing. Thereby, a pattern may be selected that takes into account the blocking of air flow through the side or sides of the smoking article in contact with the litter. In doing so, the smoking article may have both a reduced propensity to ignite and satisfactory free burn qualities. the

The smoking article has a circular or nearly circular cross-section, which implies that any part of the smoking article will not One or both sides may rest on the underlayment. In this regard, the pattern described herein defines a pattern having a film-forming mixture that does not come into contact with the substrate, regardless of the orientation of the smoking article when the smoking article comes into contact with the substrate. side or side. The smoking article may also have a non-circular cross-section. the

The wrapper and its region of additional material may comprise a plurality of discrete shapes, each extending over a length shorter than the length of the tobacco rod. At each of a plurality of longitudinally spaced locations along the tobacco rod, only the first and second shapes of the pattern are present in a cross-section taken generally perpendicular to the longitudinal axis of the tobacco rod. In one such position, said first shape is provided only on a first side of said smoking article and said second shape is provided only on a first side opposite said first side of said smoking article. on both sides. Said first shape and said second shape may be substantially 180° apart and have a porosity significantly less than that of the base paper web. If desired, the plurality of discrete shapes may be arranged such that a cross-sectional plane through the tobacco rod intersects at least two such discrete shapes. the

Thus, according to the present invention there is provided a smoking article comprising a tobacco rod having a nominal length L and a wrapper having:

a base paper web having a nominal porosity; and

a plurality of regions extending along the nominal length of the tobacco rod, each region having at least two regions of additional material spaced circumferentially around the tobacco rod and having a lower than nominal air permeability ,

Wherein said at least two additional material areas are substantially opposite to each other, and the base paper web is free of additional material in the zone between adjacent additional material areas;

Each area is laterally offset relative to the adjacent area;

wherein each region is longitudinally spaced apart from adjacent regions and the strips of the base web between adjacent regions are free of additional material,

Wherein said smoking article has an ignition propensity of no greater than 25% and a self-extinguishing value of no greater than 50% under free burning conditions. the

Optionally, said propensity to ignite is not greater than 15%. the

Optionally, the additional material area is substantially quadrilateral. the

Optionally, said regions have a longitudinal pitch length along said tobacco rod, and said regions of add-on material have a region width which is less than said longitudinal pitch length. the

Optionally, the base paper web has an air permeability greater than 20 Coresta units. the

Optionally, the additional material is present on one side of the base paper web. the

Optionally, each additional zone includes a starch mixture layer. the

Optionally, each region is laterally offset relative to an adjacent region by a distance corresponding to the lateral dimension of said additional region. the

Optionally, each zone is laterally offset relative to an adjacent zone to define a helical sequence of zones of additional material along the base web

Description of drawings

Many objects and advantages of the present invention will become apparent to those of ordinary skill in the art when this specification is read in conjunction with the accompanying drawings, in which the same reference numerals apply to the same parts, and in the accompanying drawings In the picture:

Figure 1 is a perspective view of a smoking article according to a first embodiment of the invention. the

Figure 2 is an enlarged plan view of an expanded portion of the wrapper employed in the smoking article construction of Figure 1 . the

Figure 3 is an enlarged plan view of a wrapper for a smoking article showing a second quadrilateral pattern. the

Figure 4 is an enlarged plan view of a wrapper for a smoking article showing a third quadrilateral pattern. the

Figure 5 is an enlarged plan view of a wrapper for a smoking article showing a fourth quadrilateral pattern. the

Figure 6 is an enlarged plan view of a wrapper for a smoking article showing a triangular pattern. the

Figure 7 is a side view of a smoking article employing the wrapper of Figure 3, with the smoking article positioned on a substrate and oriented such that a first side of the smoking article contacts the substrate. the

Figure 8 is a side view of a smoking article employing the wrapper of Figure 3, with the smoking article positioned on a substrate and oriented such that a second side of the smoking article contacts the substrate. the

Figure 9 is a side view of a smoking article employing the wrapper of Figure 3, with the smoking article positioned on a substrate and oriented such that a third side of the smoking article contacts the substrate. the

Figure 10 is a cross-sectional view of the smoking article taken along line 10-10 of Figure 7 . the

Figure 11 is a cross-sectional view of the smoking article taken along line 11-11 of Figure 7 . the

Figure 12 is a cross-sectional view of the smoking article taken along line 12-12 of Figure 7 . the

Figure 13 is an enlarged cross-sectional view of a smoking article on a litter and showing airflow against smoldering coals. the

Figure 14 is an enlarged cross-sectional view of a smoking article removed from the litter and showing airflow against smoldering coals. the

Detailed ways

According to the present specification, the smoking article 20 of the first embodiment (see FIG. 1 ) comprises a tobacco rod 22 . The tobacco rod 22 may comprise cut filler and be surrounded by a wrapper 24 . One end of the smoking article 20 may comprise a suitable filter 26 surrounded by a suitable filter tipping paper 27 . The smoking article 20 may typically have a generally circular cross-section over the length of the smoking article. However, other cross-sectional shapes (including, for example, oval) will fall within the scope of this description. The tobacco rod 22 has a nominal length L measured along the longitudinal axis A of the smoking article 20 from the edge of the tipping paper 27 to the free end of the tobacco rod 22 . For example, the nominal length may be in the range of about 60 mm to about 100 mm. the

The wrapper 24 comprises a base paper web that is typically air permeable. The porosity of wrapping paper is typically expressed in Coresta units. Coresta units measure the air permeability of paper in terms of volumetric flow rate (ie cm ³ /sec) per unit area (ie cm ² ) per unit pressure drop (ie cm water). The base paper webs of conventional packaging papers also have a known basis weight, which is measured in grams per square meter (abbreviated "gsm"). The porosity and basis weight of base paper webs of typical smoking product papers commonly used in the industry are shown in the table below.

For purposes of this specification, the base web 24 of the wrapper preferably has an air permeability of at least about 20 Coresta units. Most preferably, the wrapper has an air permeability of greater than about 30 Coresta, such as a common base paper web having a nominal air permeability of about 33 and about 46 Coresta and a basis weight of about 25 gsm. For some applications, the base paper web may have a porosity of greater than about 60 Coresta, or greater than about 80 Coresta, or even higher porosity values. the

Referring again to FIG. 2 , the wrapper also includes pairs of additional material regions (eg, opposing pair of regions 34d, 36d ) at a plurality of spaced locations along the tobacco rod 22 of FIG. 1 . the

Each pair of rectangular regions (eg 34a and 36a, the latter not visible in Figure 1) defines a circumferential region 31 (eg region 31a). The "width" of the striped region 31a is measured from the leading edge 7 (which is closest to the approaching coal) to the trailing edge 9 (which is furthest from the approaching coal) of the region 31a. Preferably, the width of the region (eg 31a) is in the range of about 5.5mm to about 12mm, more preferably in the range of about 7mm to about 10mm, and most preferably in the range of about 8mm to about 9mm. Furthermore, at each circumferential region (eg, region 31a ), zone 34a and zone 36a are circumferentially spaced such that they are disposed in opposing relationship to each other along opposite sides of wrapper 24 when formed on tobacco rod 22 . Preferably, each zone 34a, 36a extends circumferentially over a cross-measure (i.e., a cross-measure relative to the paper web) of about 5 mm to about 9 mm, more preferably a cross-measure of about 6 mm to about It extends circumferentially within a range of 7mm. the

By convention, note that when describing the dimensions of the various embodiments herein, "width" will extend longitudinally along the tobacco rod, but circumferential dimensions will be in terms of "transverse" or "cross- direction)" or "cross-measure". the

Note also that the base paper web is in areas 33 between adjacent areas 31a and 31b as well as areas between opposing areas within each area (e.g. between opposing areas 34b and 36b of area 31b). ) is preferably substantially free of additional material making up the regions (eg, regions 34b, 36b). the

The longitudinal distance between adjacent regions (eg, between regions 31a and 31b), referred to as the strip spacing 33, is preferably from about 4mm to about 12mm, and more preferably from about 6mm to about 8mm. the

Preferably, the respective opposing zones 34, 36 in each zone 31 are offset to some extent (according to the teachings that follow) relative to those in the front row or zone, and a sufficient number of zones 31 are formed along a given tobacco rod (for each selected strip area width and strip area spacing width) such that when the smoking article is placed on the substrate, there is at least one location 101 along the tobacco rod 22 at which at least one location 101 corresponds to Pairs of regions 34 (eg, a pair of opposing regions 34b, 36b in FIG. 1 ) are oriented substantially laterally along the tobacco rod 22 . It is at or near this portion of the tobacco rod 22 (position 101) that self-extinguishing is most likely to occur. Hereinafter, this most closely oriented position along the tobacco rod 22 is referred to as an "oriented snuffer region 101". the

Because the smoking article 26 may be placed on a different tray than that shown in FIG. 1 and/or because the pattern of its zones may be different, it will be appreciated that for different rotational positions of the tobacco rod 22, the directional extinguishing zone 101 may be along the The tobacco rod 22 occurs at different longitudinal positions. The pattern of zones and strip spacing 33 may be selected such that a plurality of directional extinguishing zones 101 may be produced along the tobacco rod 22 . the

Preferably, each zone 34, 36, 36' includes sufficient add-on material to reduce the air permeability of the wrapper at each zone to from 0.0 Coresta to about 10 Coresta, more preferably to about 7 Coresta or less. the

For the purposes of this specification, a pattern of additional material is applied to the wrapper 24 to obtain improved ignition propensity properties and also to achieve improved self-extinguishing properties. Ignition Tendency is a standard test performed as described in ASTM E2187-04 "Standard Test Method for Measuring the Ignition Strength of Smoking articles", which is hereby incorporated by reference in its entirety . Ignition propensity measures the likelihood that the smoking article will generate sufficient heat to keep the tobacco rod 22 statically burning when placed on the litter. Low values of ignition propensity are desirable because such values relate to the reduction in the likelihood that a smoldering smoking article will cause ignition of the underlying litter. the

Self-extinguishing here refers to the smoldering characteristics of smoking articles under free burning conditions. For the assessment of self-extinguishing, laboratory tests are performed at a temperature of 23°C ± 3°C and a relative humidity of 55% ± 5%, which should be monitored by a recording thermo-hygrometer. The fume hood exhausts the combustion products formed during the test. Before testing, the smoking articles to be tested are placed under the conditions of a temperature of 23°C±3°C and a relative humidity of 55%±5% for 24 hours. Just before testing, the smoking articles were placed in glass beakers to ensure free entry of air. the

The self-extinguishing test is carried out in the packaging box or test box. A single port smoking machine or electric igniter is used to ignite the smoking article for testing. During testing, a device or "angle holder" holds the smoking article to be tested by holding an end at an angle of 0° (horizontal), 45° and/or 90° (vertical). Preferably, twenty (20) smoking articles are each tested at the 0°, 45° and 90° positions. If more than one device is used, the devices are preferably positioned such that the smoking articles face away from each other to avoid cross interference. If the smoking article extinguishes before the leading line of smoldering coal reaches the tipping paper, the result is marked as "self-extinguishing"; on the other hand, if the smoking article continues until the leading line of smoldering coal reaches said tipping paper smoldering, then the result is marked as "not extinguished". Thus, for example, a self-extinguishing value of 95% means that 95% of the smoking articles tested exhibit self-extinguishing under free-burning conditions; Only 20% appeared to be self-extinguishing. the

The self-extinguishing value can be expressed according to "self-extinguishing value at 0°", "self-extinguishing value at 45°" or "self-extinguishing value at 90°", and each value refers to the self-extinguishing value at the calibrated test angle. In addition, the self-extinguishing value can also be expressed by "self-extinguishing average value", and the self-extinguishing average value refers to the average value at the three angular positions, that is (i) "self-extinguishing value at 0°", (ii) Average value of "self-extinguishing value at 45°" and (iii) "self-extinguishing value at 90°". When referring to "self-extinguishing value", it does not distinguish between the self-extinguishing value at 0°, the self-extinguishing value at 45°, the self-extinguishing value at 90° or the average value of the self-extinguishing value, but may refer to any one of them. the

The expression "self-extinguishing under free-burning conditions" or "self-extinguishing under free-burning conditions" as used herein refers to the extinguishing of a smoldering cigarette when it is under free-burning conditions without being smoked . the

As currently understood, staggered regions of add-on material in accordance with the present specification allow for the design of a smoking article 20 (see FIG. 1 ) to have a beneficial combination of low ignition propensity values and low self-extinguishing values. The pattern of areas of add-on material of low air permeability provides areas of film-forming compound along the length of the tobacco rod 22 which are capable of interacting with the film-forming compound when the smoking article is placed on the substrate. The litter cooperates to extinguish a lit smoking article 20; however, these zones of additional material (e.g., film-forming mixture) cause the smoking article 20 to self-extinguish when the smoking article 20 is held by a smoker under free-burning conditions. The statistical probability is low. Thus, according to the present specification, by applying a pattern 30 of film-forming mixture to a base paper web, smoking articles 20 can exhibit a reduced propensity to ignite while retaining desirable free burn qualities or low self-extinguishing values. the

In order to obtain the desirable ignition propensity and self-extinguishing properties of the smoking article, it is preferred that the base paper web 24 is in the unrolled condition (such as shown in Figure 2) or while the base paper web 24 is still not slit. The pattern 30 (see Figure 2) is applied to the base web 24 of the wrapping paper as it is wound onto a roll of cigarette paper on a spool. It is an object of the present specification to provide a wrapper which, when formed into a tobacco rod 22, exhibits an ignition propensity value of no greater than 25 and a self-extinguishing value of no greater than 50. Even more preferably, the resulting smoking article has an Ignition Propensity Value of no greater than about 15; most preferably, the resulting smoking article has an Ignition Propensity Value of no greater than about 10. Lower self-extinguishing values are also desirable. In this regard, a more preferred self-extinguishing value is less than about 25, and a most preferred self-extinguishing value is less than about 10. the

Referring specifically to Figure 2, the transverse dimensions of the wrapper 24 are selected based on the diameter of the finished smoking article (about 7mm to about 10mm) and taking into account material overlap at the longitudinal seam of about 1mm to 2mm. For example, considering a 1 mm overlapping seam, for a smoking article having a circumference of about 25.6 mm, the cross-web dimension of the wrapper may be about 27 mm. the

Preferably, the pattern is applied to the base paper web such that a plurality of circumferentially extending regions 31a, 31b, 31c, 31d are provided at a plurality of spaced locations along the tobacco rod 22 (see arrow B in FIG. 2 dotted line to define). The additional material can be applied to one or both sides of the base paper web. In the nominal length of the tobacco rod 22, preferably 3-6 and most preferably 4-6 or more regions 31 are created. Each circumferential region 31a, 31b, 31c, 31d has a longitudinal pitch along the tobacco rod 22 (that is, the length measured along the tobacco rod from the beginning of one region to the beginning of an adjacent region), the longitudinal pitch Less than the nominal length of the tobacco rod 22. By choosing a longitudinal pitch of about 25% of the nominal length, four zones will be provided on each tobacco rod 22. the

At least two zones of additional material (eg 34a, 36a) are provided in each circumferential region (eg 31a). Note that areas of additional material in all figures are identified with stippling to aid in their identification. However, these regions of additional material may or may not be visually identifiable in the smoking article or the wrapper for such a smoking article. Each of these zones is preferably spaced circumferentially such that the zones will oppose each other in the finished tobacco rod 22 . Furthermore, for each triplet of zones, exemplified by 31a, 31b, 31c, the zones 34b, 36b of the second zone 31b are preferably circumferentially offset relative to the zones 34a, 36a of the first zone. Furthermore, the zones 34c, 36c of the third region 31c are preferably circumferentially offset relative to the zones 34b, 36b of the second zone 31b, and further circumferentially offset relative to the zones 34a, 36a of the first zone 31a. the

As shown in FIG. 2, in this embodiment, the additional area of each zone is laterally offset circumferentially relative to the additional area of an adjacent zone by a distance that is a function of the lateral dimension of the additional area. Each zone has a width measured along the tobacco rod 22 and a transverse dimension measured along the circumferential direction of the tobacco rod 22 . For this embodiment, the zone width is smaller than the longitudinal pitch of the relevant zones. As shown in FIG. 2, the longitudinal pitch length may be greater than the corresponding zone width of the corresponding zone. Preferably, the additional zones in successive regions along the tobacco rod 22 are offset relative to the additional regions of adjacent regions, thereby defining a pattern 30 of regions which are inclined along the edges relative to the base web edge. lines to cover multiple parts of the base paper web. Furthermore, the pattern of additional zones may at least partially repeat itself along the length of the base paper web. the

In the illustrated embodiment (FIG. 2), each zone is placed on the wrapper 24 such that the zone is centered on one of three paths 34, 36 and 38 defined by the respective dashed lines 34, 36. and 38 to represent. Thus, for example, the path 34 passes through the corresponding geometric features of the six zones 34a, 34b, 34c, 34d, 34e, 34f. Each zone is spaced apart from other zones; however, alternatively, the zones may be in contact with each other. The paths 34 , 36 , 38 are parallel to one another and are oriented at an acute angle φ relative to the sides of the wrapper 24 . It will be appreciated that zone 36' is preferably identical to zone 36 and is obtained by the development of the pattern shown in Figure 2, wherein zone 34' appears along the opposite edge as zone 34 disappears along one edge. Each pair of cross-web aligned regions (e.g., regions 34a, 36a or regions 34b, 36b) may cover up to about 33% of the total surface area of the respective regions 31a, 31b. For rectangular zones, preferably each zone is in the range of about 8 mm to about 10 mm in longitudinal direction or width and in the range of about 5 mm to about 7 mm in the circumferential transverse measurement direction. The longitudinal spacing 33 between zones is preferably in the range of 4mm to about 12mm, and more preferably in the range of about 6mm to about 8mm. The circumferential spacing of the zones of additional material is preferably in the range of about 3mm to about 20mm, more preferably in the range of about 5mm to about 8mm, and most preferably in the range of about 5.5mm to about 7.0mm. the

When the wrapper 24 is formed around tobacco to make the tobacco rod 22, the areas of additional material at any longitudinal position are preferably spaced about 180 degrees apart from each other. In addition, the ratio of the area occupied by the zones of additional material to the total area of (i) the corresponding zone 31d and (ii) the phase on one side (i) the corresponding zone 31d on one side (this ratio is defined herein as the "zone area ratio") is significantly less than one. The sum of the circular areas between adjacent regions. Preferably, the zone area ratio is in the range of less than about 20% to less than about 50%, and more preferably in the range of about less than about 20% to less than about 35%. More particularly, in some embodiments, the zone area ratio between the zone occupied area and the total area may be less than 30%, or even less than 25%. In general, it is desirable to keep zone area coverage low, since high values (eg, closer to 1) are believed to reduce CO in mainstream smoke when low porosity (i.e., low Coresta) wrappers are used for tobacco rods. Concentration increases. the

When wrapper 24 is formed to make tobacco rod 22, paths 34, 36, 36' describe a first helical path 36/36' (regions 36 and 36' in Figure 2 combine to form helical path 36/36') , and a second helical path 34 (including a helically aligned zone 34), both helical paths extend longitudinally around the axis A and over the entire length of the tobacco rod 22, as shown in FIGS. 7-9. Helical paths 36/36' and 34 (shown in FIG. 2) have a helix angle φ and do not intersect each other. Preferably, the two helical paths may rotate in a counterclockwise direction or in a clockwise direction around the tobacco rod 22 . As shown, the two paths 34, 36' follow a clockwise path from the filter end of the tobacco rod 22 when viewed from the lit end towards the filter end. the

By applying one or more layers of an aqueous film-forming composition (aqueous film-forming composition) to the base paper web of the packaging paper, multiple regions of the pattern 30 can be formed to reduce the air permeability of the paper in these regions. Spend. Alternatively, fibrous material can also be used to form multiple zones. Where a film-forming composition is used, the film-forming composition preferably may contain water and a high concentration (eg, 20% to about 50% by weight) of a plugging agent. The film-forming compound may contain one or more plugging agents such as starch, alginate, cellulose or gum, and may also contain calcium carbonate as a filler. A concentration of about 24% may be beneficial when the starch is a film forming mixture. The film-forming composition may be applied to the base web of wrapper 24 using gravure printing, digital printing, by stencil coating or spraying, or any other suitable technique. For example, the film-forming mixture and method for applying the film-forming mixture described in U.S. Patent Application No. 11/500,918, which is hereby incorporated by reference in its entirety, may be selected for printing a pattern onto a base web of wrapping paper. If desired, areas of additional material may be formed by printing multiple successive layers (eg, two or more successive layers aligned or registered with each other). Furthermore, when multiple layers are used to form additional material regions, the materials in the multiple layers may be the same or different. For example, one layer could be starch and the next layer could be starch and calcium carbonate (or vice versa). the

A presently preferred embodiment for a pattern 30 of regions of additional material is shown in FIG. 3 . Like the embodiment of FIG. 2 , the area of additional material in FIG. 3 is quadrangular, in particular substantially rectangular. Preferably, at least two regions of add-on material (eg 40a, 40b) are applied in each region 31a, 31b, 31c, 31d so as to be spaced circumferentially in the finished smoking article. The circumferential dimension of each zone 40a, 40b is preferably selected to be less than about 50% of the transversely measured dimension of the base paper web 24 when unrolled, and most preferably about 25% of the transversely measured dimension of the base paper web 24 or the circumference of the tobacco rod 22. %. The sum of the circumferential dimension of each zone 40a, 40b plus the circumferential spacing between the zones 40a, 40b is preferably about 50% of the circumferential CD dimension of the base paper web 24. the

The sum of the longitudinal length of the zones 40a, 40b plus the longitudinal spacing 33 between the zones 40a, 40b and 42a, 42b (i.e. the longitudinal pitch length) is preferably chosen such that the nominal length of the tobacco rod 22 of the smoking article Three or four regions 31a, 31b, 31c, 31d will be produced, with additional regions of adjacent regions spaced apart from each other in the longitudinal direction. Preferably, the longitudinal extent or "width" (ie zone width or region width as previously defined) of the zones (eg 40a, 40b) is in the range of about 8 mm to about 10 mm. The circumferential offset x between (i) zones 42a, 42b of zone 31b and (ii) zones 40a, 40b of zone 31a is preferably in the range of about 10% to about 35% of the developed total transverse direction measurement of base paper web 24 In the range. More preferably, the circumferential offset x is in the range of about 12% to about 35% of the developed total cross-direction measurement of the base web 24. Most preferably, the circumferential offset x is approximately half the circumferential or transverse dimension of the additional zone 40a, 40b. The zones of additional material in the other regions 31c, 31d are similarly offset further circumferentially with respect to each other by the same offset x. Note that, for example, a zone of additional material areas 46a, 46c is separated between two edges of the base paper web 24 in region 31d when the base paper web is in the unrolled condition. the

The pattern applied in zones 31 a - 31 d preferably repeats along the length of base paper web 24 . Clearly, if the circumferential offset x is less than 12.5% of the crosswise width of the base web, then more than four regions will define a complete period or phase length of the pattern 30 . Conversely, if the circumferential offset x is greater than 12.5% of the crosswise width of the base web, then four or fewer regions will define the complete cycle length of the pattern 30 (like the pattern shown in Figure 2). the

Another embodiment of pattern 30 (see FIG. 4 ) employs quadrilateral additional material regions 60a, 60b, ie substantially parallelogram shaped regions. Although the regions 60a, 60b are arranged in generally helical alignment with each other when the wrapper is formed into the tobacco rod 22, the configuration of the parallelogram shapes 60, 62, 64, 66 may be selected as desired. For example, mirroring of the shape (mirroring around the longitudinal direction) may be employed, even though the general helical impression may be lost. Likewise, the slope of the parallelogram region can also be varied as desired. In general, however, in this embodiment, the circumferential dimensions, circumferential spacing or offsets, longitudinal dimensions, and longitudinal spacing or offsets of the regions 60, 62, 64, 66 and regions 31a-31d can be determined according to other selected as described in the examples. the

A further embodiment of the pattern 30 (see FIG. 5) employs quadrilateral additional material areas 70, 72, 74, 76, ie substantially trapezoidal areas. Here, again, when the wrapper is bonded to the tobacco rod 22, the generally trapezoidal regions 70a, 72a may be arranged in generally helical alignment with each other. Furthermore, the actual shape of the trapezoidal regions 70, 72, 74, 76 can be selected as desired. For example, the slope of the trapezoidal regions and the proportions of the trapezoidal regions can be varied as desired. In general, however, in this embodiment, the circumferential dimensions, circumferential spacing or offsets, longitudinal dimensions, and longitudinal spacing or offsets of the regions 70, 72, 74, 76 and regions 31a-31d can be determined according to other selected as described in the examples. Preferably, the front edge 7 is the longer of the two parallel sides of the zone 70 . the

Yet another embodiment of the pattern 30 (see FIG. 6 ) employs generally triangular-shaped regions of add-on material 80, 82, 84, 86. The generally triangular-shaped regions 80a, 80b of a region 31 may be constructed and arranged to contact the corresponding generally triangular-shaped regions 82a, 82b of a next adjacent region 31b. The generally triangular-shaped regions 80a, 80b of the first region 31a may be spaced longitudinally from the triangular-shaped regions 82a, 82b of the adjacent region 31b if required by the desired ignition propensity and self-extinguishing characteristics. Depending on the characteristics required for the design of the smoking article, it may also be considered to orient the generally triangular region such that the burning coal of the smoldering smoking article encounters the apex of the triangle and the progressively increasing transverse dimension of the generally triangular region (i.e. in Figure 6 , from right to left in Figure 6), or such that the burning coal of the smoldering smoking article encounters the base of the triangular zone and the sharp increase in the zone of lower air permeability (ie, from left to right in Figure 6). The circumferential spacing of the triangular regions 80, 82, 84, 86 and the dimensions of these triangular regions can be determined according to the preferred ranges described elsewhere in this specification. In addition, the triangular region may be an isosceles triangle as shown, an equilateral triangle, a right triangle, or any other desired satisfactory triangular shape. In general, however, in this embodiment, the circumferential dimensions, circumferential spacing or offsets, longitudinal dimensions, and longitudinal spacing or offsets of the regions 80, 82, 84, 86 and regions 31a-31d can be determined according to other selected as described in the examples. Preferably, the triangular shaped zone 80 is oriented so as to form the front edge 4 (closest to the approaching coal). the

The three different positions in which the smoking article 20 sits on the substrate 98 illustrate the resulting fit between the region of low air permeability add-on material and the substrate 98 . One position (see Figure 7) shows a side view of a smoking article 20 according to the present specification. Rotating the smoking article about its longitudinal axis through an angle of 45 degrees (clockwise as viewed from the left end of Figure 7) the same view as that shown in Figure 8 is obtained. Similarly, by rotating the smoking article 20 a further 45 degrees (clockwise as viewed from the left end of Figure 7), the view shown in Figure 9 is obtained. In each of Figures 7 to 9 it can be seen that at least one pair of regions of additional material are located on the sides of the smoking article at a location along the length of the tobacco rod 22, such as regions 92, 92', Regions 94, 94' of FIG. 8, and regions 96, 96' of FIG. At these locations, the regions of add-on material are substantially on the sides of the smoking article 20 (see FIG. 12 ), and the regions 92 , 92 ′ are substantially upstanding or generally perpendicular to the surface of the substrate 98 . This orientation of the regions 92, 92' is best shown in Figure 12, where the opposing regions 92, 92' are located on respective opposite sides of the smoking article 20 when viewed in cross-section, and opposite The diameter of the tobacco rod 22 is substantially parallel to the surface of the substrate 98 and is positioned substantially symmetrically. the

Figures 10 and 11 illustrate the orientation of regions of add-on material at other longitudinal positions along the smoking article 20. In FIG. 10 , the areas of add-on material 90 , 90 ′ are positioned such that one area 90 contacts the underlayment 98 . The regions 94, 94' of the smoking article 20 in Fig. 7 would also be positioned as in Fig. 10 when viewed from the right end of Fig. 7 . In FIG. 11 , one zone 96 ′ is in contact with the substrate 98 , but the other opposing zone 96 is on top of the smoking article 20 . From a consideration of Figures 7 to 9, it will be appreciated that, regardless of the angular position of the smoking article 20 having the described pattern of add-on material areas, at least one pair of opposing add-on material areas is as shown in Figure 10 or Figure 12 or in rotational positions between those positions. This positioning has been referred to above as directional extinguishing area 101 . the

The regions 92, 92', by virtue of their reduced air permeability, impede the air flow of the burning coal against the tobacco rod 22 when the smoking article 20 is present under free burning conditions (see Figure 14). Instead, the bottom 104 of the wrapper freely allows air to enter the sides of the tobacco rod 22 to support the combustion of the coal. A very different situation arises when smoking articles 20 are placed on a tray 98 (see Figure 13). Here, the underlayment 98 prevents the upward flow of air towards the bottom 90 of the tobacco rod 22 . The zones 92, 92' and the underlayment 98 cooperate to define a much smaller zone 100, 102 available for conveying air through the base paper web. More specifically, the vertical zone 100 between the bottom of the zone 92 and the underlayment 98 and the vertical zone 102 between the bottom of the zone 92′ and the underlayment 98 make it possible for air to pass through to reach the opening of the tobacco rod 22. The area of smoldering coal is significantly reduced. Due to the lack of oxygen in the air, the smoldering coal self-extinguishes when the burn line reaches the opposite add-on material zone positioned as shown in FIG. 13 . The significantly reduced area of air available to support the combustion of the coal also exists in the rotated position of the tobacco rod 22 between the position shown in FIG. 10 and the position shown in FIG. Figure 12, however, shows the location where the area available for incoming air flow is minimized. Similarly, if the smoking article is placed on the litter 98 in a position where any other pair of additional material regions has substantially the position shown in Figure 13, then auto-occurrence may also occur at these other pairs of regions. put out. the

However, when the smoking article is placed on the substrate 98 so that an additional zone contacts the substrate 98 generally as shown in FIG. There is less material cohesion between the underlayment 98 and the additional zone than occurs at the extinguishing zone 101, resulting in a reduction in this area. the

In the preceding examples, the discussion of having a wrapper (on the Reduced ignition propensity values, reduced self-extinguishing values, and improved free burn qualities of smoking articles 20 with formed patterns 30). Naturally, this discussion is for the sake of brevity. It will be readily understood that the pattern according to the present specification enables the smoking article to be extinguished regardless of which side of the smoking article rests on the support 98, and does not require the extent to which the film-forming mixture is applied to the paper To the extent that the desired natural burn qualities in the smoking article are lost. This can be understood by realizing that the opposing film-forming mixture regions need not occur at exactly 90 degrees from the side in contact with the substrate 98 . These regions may be centered at a location closer to or farther from the side contacting the pad 98 , such as between about 60° and 120° from the side contacting the pad 98 . the

Furthermore, the ability to extinguish the smoking article may depend more on setting a minimum length range of add-on material (e.g., film-forming mixture) than on a specific weight per unit area of film-forming mixture at a longitudinal position for a particular chosen pattern . For example, the length of the rectangular region may be no less than about 5.5 mm for the particular design, base web, and film-forming mixture employed. The amount of film-forming mixture employed can be increased to improve ignition propensity properties, usually without loss of free-burning qualities; and, if desired, combustion accelerators can be applied to the paper to support even higher Additional levels. the

Preferably, the zone of add-on material reduces the air permeability of the wrapper to a range of about 0 Coresta to about 10 Coresta. the

It was previously believed that a 3:1 air permeability ratio between the base paper web and the add-on material area was not sufficient to extinguish the smoking article because there was insufficient air permeability reduction in the machine direction position of the paper. However, when there is an underlying substrate 98 and when the add-on material is located on the side of the smoking article that is not in contact with the substrate 98, over a portion of the circumference of the smoking article, this air permeability ratio may be sufficient to allow smoking. The smoking product goes out. the

Therefore, it can be appreciated that the helically rotated positions of the opposing add-on material areas create a situation in which, no matter which side of the wrapper rests on the dunnage 98, there will always be at least one longitudinal position, the at least one longitudinal position The position has the film-forming compound at the side that is not in contact with the underlayment 98 and still has sufficient additional volume and geometry to enable the zone to cooperate with the underlayment 98 so that when the burn line reaches this longitudinal position Make smoking articles self-extinguishing. This fact improves the ignition propensity performance of the smoking article and allows smoking articles to be designed with an ignition propensity value of no greater than 25%. However, in the absence of the pad holder 98 (such as when the smoking article is held by a smoker), the smoking article still does not self-extinguish but remains free-burning. This improves the self-extinguishing properties of the smoking article and allows smoking articles to be designed with a self-extinguishing value of no greater than 50%, which may be the self-extinguishing average. The self-extinguishing value at 0 degrees can be much lower than the self-extinguishing average and can be less than 25%. the

In the above embodiments, the smoking article has a generally circular cross-section. As such, it is possible for either side of the smoking article to rest on the underlayment 98 . However, the patterns taught herein can be such that no matter which side of the smoking article happens to sit on the cushion 98, the above-mentioned burn characteristics described above with respect to Figures 13 and 14 (not greater than 25% Ignition tendency value and self-extinguishing value not greater than 50%). Preferably, the pattern is selected such that when the base paper web is wrapped around the tobacco rod 22, the film-forming mixture zone occurs at one or more longitudinal locations along the tobacco rod 22 on the opposite side that is not in contact with the underlayment 98. Having more than one longitudinal position with the film-forming mixture in a lateral position is preferred in order to accommodate the situation where a smoking article is placed on the support 98 after the burn line has traveled through a portion of the smoking article, This would cause the smoking article to extinguish; or cause the sideways add-on material areas to generally be relatively close to the burn line when the smoking article is placed on the underlayment 98 . the

If desired, areas of additional material may include other geometric shapes besides quadrilaterals, including, for example, ovals, other polygons, and the like. the

Furthermore, the aforementioned helix angle φ can be increased while keeping the size of the zones the same as in the illustrated embodiment. The variation may place the regions in an overlapping pattern (or at least bring the regions closer to each other). Alternatively, by increasing the lateral dimension of the zones or slices while maintaining the same helix angle as in FIG. 2 , or by placing Zones of equal size (so that there are 12 flakes instead of 6 flakes along the path 34), a stepped spiral pattern can be formed. the

When the word "about" or "approximately" etc. is used herein with respect to a value, it is intended to include not only the value but also values that fall within ±5% or range of the exact value to which the "about" is associated. the

It will now be apparent to those of ordinary skill in the art that this specification describes a new, useful, and non-obvious smoking article. It will also be apparent to those of ordinary skill in the art that there are numerous modifications, variations, substitutions, and equivalents to the various aspects of the smoking article that have been described in the foregoing detailed description. Accordingly, it is expressly stated herein that the invention includes all such modifications, variations, substitutions, and equivalents as fall within the spirit and scope of the invention as defined by the appended claims. the

Claims (7)

1. A smoking product, comprising shredded tobacco rod and wrapping paper, the wrapping paper has: base paper web; and a plurality of circumferential regions at spaced locations along the length of the tobacco rod, each region having at least two regions of add-on material having an air permeability greater than that of the base paper web the air permeability is low, the at least two zones of additional material are substantially opposite each other; and for at least each successive first, second and third zone, the zone of each second zone is relative to the zone of the corresponding first zone is circumferentially offset, and the zone of the third region is further circumferentially offset relative to the zone of the corresponding first zone than the zone of the corresponding second zone, Such a pattern extends substantially continuously along the tobacco rod such that when the tobacco rod is placed on a tray and viewed from one end, the orientation of at least one region will be such that the corresponding zone of the at least one region lies along the at the sides of the tobacco rod; and Said zone is of sufficient size, shape and additional material such that when said tobacco rod is placed on a litter under smoldering conditions, said tobacco rod will tend to lie in said orientation in said at least one area goes off, Wherein said smoking article has an ignition propensity of no greater than 25% and a self-extinguishing value of no greater than 50% under free burning conditions. 2. The smoking article according to claim 1, wherein the region of add-on material is substantially quadrangular. 3. The smoking article according to claim 1 or 2, wherein said regions have a longitudinal pitch length along said tobacco rod and said regions of add-on material have a region width which is less than said longitudinal pitch length . 4. The smoking article according to claim 1 or 2, wherein the base paper web has an air permeability of greater than 20 Coresta units. 5. The smoking article according to claim 1 or 2, wherein the add-on material is present on one side of the base paper web. 6. The smoking article as claimed in claim 1 or 2, wherein each region of add-on material comprises a starch mixture layer. 7. The smoking article according to claim 1 or 2, wherein each region is laterally offset relative to an adjacent region by a distance corresponding to the lateral dimension of the zone of add-on material.