TOBACCO SMOKE FILTER AND METHOD OF PRODUCTION

Abstract

A product rod comprising a plurality of individual tobacco smoke filters or filter elements abutted end to end; and a wrapper engaged around the plurality of filters or filter elements, the wrapper including perforations.

Claims

1. A method of forming a cigarette comprising the steps of: providing a plurality of individual tobacco smoke filters or filter elements abutted end to end; engaging a wrapper around the plurality of filters or filter elements; perforating the wrapper with a line of 16 to 39 perforations in register with each junction between abutted filters or filter elements; removing at least one of the tobacco smoke filters or filter elements from the plurality of the tobacco smoke filters or filter elements; and employing the at least one of the tobacco smoke filters or filter elements removed from the plurality of the tobacco smoke filters or filter elements as a filter while rolling the cigarette wherein a portion of the wrapper around the removed at least one of the tobacco smoke filters or filter elements is maintained around the removed at least one of the tobacco smoke filters or filter elements while rolling the cigarette.

2. The method according to claim 1 wherein the individual tobacco smoke filters, or individual tobacco smoke filter elements, are identical or substantially identical.

3. The method according to claim 1 wherein the wrapper is paper or other sheet material.

4. The method according to claim 3 wherein the paper has basis weight of 15-50 gsm.

5. The method according to claim 1 wherein the perforations are symmetrical.

6. The method according to claim 1 wherein the perforations are oval or rectangular.

7. The method according to claim 1 wherein the perforations are of approximate dimensions 0.1 mm to 0.7 mm.

8. The method according to claim 1 wherein the perforations are spaced at 10 to 25 holes per cm.

9. The method according to claim 1 wherein the individual tobacco smoke filters or filter elements include a substantially cylindrical core of tobacco smoke filtering material.

10. The method according to claim 1 wherein the individual tobacco smoke filters or filter elements include a self-sustaining longitudinally extending cylindrical core of tobacco smoke filtering material.

11. The method according to claim 1 wherein the individual tobacco smoke filters or filter elements include a self-sustaining longitudinally extending cylindrical core comprising a plurality of longitudinally extending substantially continuous filaments of tobacco smoke filtering material which are bonded at their points of contact.

12. The method according to claim 1 wherein the individual tobacco smoke filters or filter elements include a self-sustaining longitudinally extending cylindrical core comprising a plurality of randomly oriented fibres of tobacco smoke filtering material which are bonded at their points of contact.

13. The method according to claim 1 wherein the individual tobacco smoke filters or filter elements include one or more continuous components extending substantially longitudinally of the cylindrical core.

14. A method of forming a cigarette comprising the steps of: providing a plurality of individual tobacco smoke filters or filter elements abutted end to end; engaging a wrapper around the plurality of filters or filter elements; perforating the wrapper with a line of perforations extending from one end of the product rod to the other end and defining a helix about the periphery of the wrapper; removing at least one of the tobacco smoke filters or filter elements from the plurality of the tobacco smoke filters or filter elements; and employing the at least one of the tobacco smoke filters or filter elements removed from the plurality of the tobacco smoke filters or filter elements as a filter while rolling the cigarette; wherein a portion of the wrapper around the removed at least one of the tobacco smoke filters or filter elements is maintained around the removed at least one of the tobacco smoke filters or filter elements while rolling the cigarette.

15. The method according to claim 14 wherein the pitch of the helix defined by the line of the perforations is the length of a single individual filter or filter element.

16. The method according to claim 14 wherein the perforations are symmetrical.

17. The method according to claim 14 wherein the perforations are oval or rectangular.

18. The method according to claim 14 wherein the perforations are of approximate dimensions 0.1 mm to 0.7 mm.

19. The method according to claim 14 wherein the perforations are spaced at 5 to 25 holes per cm.

20. The method according to claim 14 wherein the individual tobacco smoke filters, or individual tobacco smoke filter elements, are identical or substantially identical.

21. A method of forming a cigarette comprising the steps of: providing a plurality of individual tobacco smoke filters or filter elements abutted end to end; engaging a wrapper around the plurality of filters or filter elements; perforating the wrapper with a line of 16 to 39 perforations in register with each junction between abutted filters or filter elements; removing one of the tobacco smoke filters or filter elements from the plurality of the tobacco smoke filters or filter elements; and employing the one of the tobacco smoke filters or filter elements removed from the plurality of the tobacco smoke filters or filter elements as a filter while rolling the cigarette; wherein a portion of the wrapper around the removed at least one of the tobacco smoke filters or filter elements is maintained around the removed at least one of the tobacco smoke filters or filter elements while rolling the cigarette.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present invention will now be illustrated with reference to the following Examples and the attached drawings in which FIG. 1 schematically illustrates a product rod of filters according to an embodiment of the invention;

[0045] FIG. 2 is a different view of the product rod of filters of FIG. 1;

[0046] FIG. 3 schematically illustrates a method and apparatus which may be used to manufacture the product of e.g. FIGS. 1 and 2;

[0047] FIG. 4 illustrates a product rod of filters according to a further embodiment of the invention; and

[0048] FIG. 5 shows the results of testing products of the invention (Example 1).

[0049] FIGS. 1 and 2 show a NWA “Rip-a-Tip”™ product rod 1 according to one embodiment of the invention.

[0050] The product rod 1 comprises six individual tobacco smoke filters 3 each of around 17.5 mm circumference and length 14 mm abutted end to end. The individual tobacco smoke filters 3 are identical with each other. Each filter 3 includes a self-sustaining substantially cylindrical core formed from a plurality of longitudinally extending substantially continuous filaments of crimped cellulose acetate tow which are bonded at their points of contact (i.e. each filter 3 is a NWA filter). The product rod 1 also includes a wrapper 5 comprising paper of basis weight 25 gsm which is engaged around the filters 3 thereby forming a wrapped cylinder of six filter elements of length 84 mm. As is best seen in FIG. 2, the wrapper includes five lines of perforations 7, each line including thirty oval holes of hole size about 0.6×0.3 mm (aligned such that the length of each oval hole is aligned with the longitudinal axis of the product rod 1). Each line of perforations 7 is in register with a junction between two abutted filters 3 (in other words, in register with each region where adjacent filters or filter elements abut each other). The holes in the wrapper can be made by any means known in the art, e.g. laser, mechanical or electrostatic means; suitable methods are described below.

[0051] In use the smoker takes product rod 1 and pulls or bends the rod at the join closest to one end of the product rod (indicated by the line of perforations closest to the end) to snap off an individual filter; the filter is then used when rolling a RYO cigarette. The oval holes of hole size about 0.6×0.3 mm are sufficiently large that the consumer can see them on the outside of the finished rod 3, enabling him to clearly identify the point at which the rod should be snapped. The lines 7 of perforations (holes) enable a clean break between adjoining tips to be achieved—a jagged break would be unsightly and unacceptable to the consumer. The section of the outer wrapper 5 around the individual filter is retained and forms part of the filter to be used, rather than becoming redundant (and discarded) in the case of conventional Pop-a-Tips.

[0052] FIG. 3 shows a method and apparatus according to a further embodiment of the invention which may be used to manufacture the product of FIGS. 1 and 2.

[0053] As can be seen in FIG. 3 a flow of pre-formed filters 103 and pre-formed dual filter rods 103a is longitudinally advanced in the direction of arrow 104 into a garniture unit 106.

[0054] The pre-formed (identical) filters 103 are each of around 17.5 mm circumference and length 14 mm. Each filter 103 includes a self-sustaining substantially cylindrical core formed from a plurality of longitudinally extending substantially continuous filaments of crimped cellulose acetate tow which are bonded at their points of contact. The pre-formed dual filter rods 103a are each of around 17.5 mm circumference and length 28 mm. Each rod 103a includes a self-sustaining substantially cylindrical core formed from a plurality of longitudinally extending substantially continuous filaments of crimped cellulose acetate tow which are bonded at their points of contact. The filters 103 are NWA filters and may, as well as dual rods 103a, be manufactured by a process similar to that described in UK Patent No. 1169932 (U.S. Pat. No. 3,455,766), in which filaments of cellulose acetate tow to which a plasticiser has been applied are fed into a forming station where a belt is folded around the tow until the longitudinal edges of the belt are juxtaposed and the tow is confined within the belt; the tow is thus formed into a longitudinally extending cylinder by the belt. The belt is then moved to a heat treating station where a heating fluid (e.g. steam) is passed through the belt into contact with the tow to activate the plasticizer. The belt and tow therewithin are then moved through a cooling station where cool air or other fluid is passed through the belt into contact with the tow to deactivate the plasticizer, if necessary, and dry the tow by removal of condensed steam, whereby the tow is made rigid to form a continuous self sustaining and stable longitudinally extending rod. The continuous self sustaining and stable longitudinally extending rod is cut into base rods of filters for subsequent use also by methods well known in the art.

[0055] Conventional Pop-a-Tip manufacture takes place on a dual rod filter making machine. These machines are well known in the art and normally used for combining two different types of base rod, which are held in two different hoppers on the machine. For Pop-a-Tip manufacture the two hoppers are filled with the same base rod type and these base rods are cut down (to provide the required tip length), aligned in an end-to-end relationship, wrapped in transparent film and cut to the final required Pop-a-Tip length. In the process of making product rods according to the present invention the two hoppers of the dual rod filter making machine (not shown) are also filled with base rods of filters 103 manufactured as set out above. One hopper is used to cut down the base rods to individual filters 103 of the required tip length (14 mm) and the other hopper is used to cut down the base rods to dual filter rods 103a of the required tip length (28 mm) and the dual rod machine is then set to arrange and align the filters 103 and dual filter rods 103a in an end-to-end relationship such that each dual filter rod 103 is separated form the next rod 103a by four individual filters 103 to provide the flow of pre-formed filters 103 and multiple (dual) filter rods 103a. As can be seen in FIG. 3 the filters 103 are aligned and abutted end to end (i.e. there are no spaces between individual filters 103 or filters 103 and filter rods 103a) prior to longitudinal advancement in the direction of arrow 104 into the garniture unit 106.

[0056] The garniture unit 106 includes a compression shoe 108 through which the aligned and abutted filters 103 and dual filter rods 103a are passed prior to wrapping in the garniture. Compression shoes are known in the art for control of the final circumference of the finished rod.

[0057] A wrapper 105 of paper of basis weight 25 gsm is applied to the continuously advancing flow of filters or filter elements in the garniture 106 in the conventional manner, to thereby form a continuous wrapped rod 111 comprising groups of four individual filters 103 separated by dual filter rods 103a. The continuous wrapped rod 111 is then cut in register with a position half way along each dual filter rod 103a (see arrow 222) by methods known in the art to provide intermediate product rods of around 17.5 mm circumference and 84 mm length, each containing six individual, identical, 14 mm long filters 103 in a common paper wrapper.

[0058] It is essential that each line of perforation holes (in the above case these would be spaced 14 mm apart) are closely aligned with (in register with) the region where adjoining tips abut. This may be achieved by the use of an on-line laser perforation system (not shown) after each filter rod (e.g. of 84 mm length) has been assembled. Such a laser perforator generates holes around the periphery of the rod in defined locations in a manner that is well-known for the online perforation of filter ventilation holes during cigarette assembly. The laser perforator generates five lines of perforations around the periphery of the rod: each line includes thirty oval holes of hole size about 0.6×0.3 mm, e.g. 0.4×0.2 mm; and each line of perforations is in register with a junction between two abutted filters. The resulting perforated product rod is a product as shown in FIGS. 1 and 2.

[0059] It will be appreciated that there are other ways in which the perforations may be achieved, including: a) use of a pre-perforated wrapper in which the perforations are aligned in rows across the width of the wrapper, each row being separated from the adjacent row by a distance (e.g. 14 mm) corresponding to the length of the filter and then employing a suitable registration system to ensure that these rows are maintained in alignment with the flow of filter tips during filter rod assembly; and b) a system similar to (a) in which, rather than the wrapper being pre-perforated, a series of lateral perforation lines are generated in the (non-perforated) wrapper as part of the filter production process immediately prior to it being used to wrap the filter tips.

[0060] FIG. 4 shows a NWA “Rip-a-Tip”™ product rod 51 according to another embodiment of the invention.

[0061] The product rod 51 comprises six individual (identical) tobacco smoke filters 53 each of around 17.5 mm circumference and length 14 mm abutted end to end. Each filter 53 includes a self-sustaining substantially cylindrical core formed from a plurality of longitudinally extending substantially continuous filaments of crimped cellulose acetate tow which are bonded at their points of contact (i.e. each filter 53 is a NWA filter). The product 51 also includes a wrapper 55 comprising paper of basis weight 25 gsm which is engaged around the filters 53 thereby forming a wrapped cylinder of six filter elements of length 84 mm. The wrapper includes a lines of perforations 57 extending from one end of the product rod 51 to the other (end) and defining a helix (spiral) about the periphery of the product rod. The perforations are oval holes of hole size about 0.4×0.2 mm.

[0062] The holes in the wrapper can be made by any means known in the art, e.g. laser, mechanical or electrostatic means, e.g. by the methods described above. It will be appreciated that if the wrapper is pre-perforated (i.e. perforated before application to the filters/elements of the product rod), the perforations (holes) will have to be carefully located so they form a continuous helix after the wrapper is wrapped around the filters/elements.

[0063] In use of the embodiment of FIG. 4, the consumer peels back a strip of the wrapper along the helical line of perforations to allow individual filter tips to be sequentially released for use; the remaining portion of the wrapper holds the remaining filters in place. It will be appreciated that in this case the wrapper is discarded, rather than remaining part of the filter.

[0064] In another example (not shown) the pitch of the helix defined by the line of the perforations 57 (that is the distance along the helical axis and also along the product rod that results in one full turn of the helix) may be 14 mm, the length of a single individual filter or filter element. In this example, peeling back a single turn of the helix of the wrapper releases a single filter/filter element.

EXAMPLES

Example 1

[0065] The applicants carried out trials to identify the most appropriate size and spacing of holes to enable (i) a clean break, or “snap” of the filter from the product rod and (ii) a suitable visual cue for the consumer.

[0066] The applicants made filter rods (of 17.9 mm circumference) similar to those shown in FIGS. 1 and 2, using NWA filters and a perforated plugwrap paper. The plugwrap paper was perforated with various numbers of either rectangular or oval holes of nominal dimensions 0.2×0.4 mm (with the length of hole orientated along the length of the paper/filter rods—in other words the holes are oriented with their longest axis (i.e. the hole length) perpendicular to the line of perforations). Measurements subsequently made using a microscope showed that the actual hole size was closer to 0.6×0.3 mm.

[0067] The manufactured rods were tested by “snapping” or pulling off one filter from the rest along the line of the perforations.

[0068] The following Table shows the results.

TABLE-US-00001 Number of holes Rectangular holes Oval holes 10 Uneven Uneven “snap”/tearing “snap”/tearing 15 Uneven Uneven “snap”/tearing “snap”/tearing 20 Uneven Fair ease of “snap”/tearing separation and quality of separation line 25 Fair ease of Good ease of separation and separation and quality of quality of separation line separation line 30 Good ease of Very good ease of separation and separation and quality of quality of separation line separation line (see FIG. 5) (see FIG. 5) 35 Very good ease of Excellent ease of separation and separation and quality of quality of separation line; separation line; rod unstable/weak rod unstable/weak

[0069] In all cases, the oval hole shape provides a smoother and more even separation line after ripping (“snapping”) an individual filter off the rod (FIG. 5).

[0070] The best results in terms of ease of separation and the quality of the separation line were obtained with 35 holes for rectangular hole shape; however, similar results were obtained with 30 holes for the oval hole shape (FIG. 5), and even better results in terms of ease of separation were obtained with 35 holes for oval hole shape. However, with 35 holes the rod became unstable and there is a risk of significant difficulty processing the plugwrap with this pattern in production and of the rod becoming unstable during packaging and transportation. Thus, the pattern with 30 oval shaped holes provides the best results in terms of ease of separation, rod stability and the quality of the separation line.

[0071] The example therefore shows that 30 to 35 rectangular or oval shaped holes of nominal dimensions 0.4×0.2 mm around the circumference of a 17.9 mm circumference Pop-a-Tip provide optimum ‘snap’ characteristics (see FIG. 5). Less than around 15 holes of such size give an uneven ‘snap’, whilst more than 35 or 40 holes can result in the paper being too weak to be processed on conventional filter making or packaging machinery.

Example 2

[0072] This Example measures the tensile strength of a plug wrap that has been perforated in accordance with aspects of the invention. The test is designed to assess the runnability of a pre-perforated paper on a filter making machine.

[0073] Strips of non-porous plug wrap paper of 27 gsm basis weight as supplied by Papierfabrik Wattens GmbH of Austria were perforated by laser providing an array of holes each nominally 0.4×0.2 mm. An array of holes were produced at 10, 20, 30, 40, 50 and 60 holes per 17.5 mm width and the tensile strength measured.

[0074] The results were as follows:

TABLE-US-00002 Number of Holes/17.5 mm Mean Tensile Strength (Kgf) 0 2.29 10 2.35 20 2.23 30 1.78 40 1.75 50 1.47 60 1.39

[0075] The test method involved cutting the plug into test pieces of 180 mm length×15 mm width, with each test strip having a single line of holes. Testing was carried out using a Lloyd L500 tensile tester, using a load range of 0-10.0 Kgf, extension range 0-1000 mm and crosshead speed set to ensure that the sample broke within 15 to 25 seconds.

[0076] A surprisingly high level of tensile strength was retained, even at the more extreme number of holes where the paper was visually almost completely cut through.

[0077] These data confirm the runnability of the plug wrap on filter making machines: even at the highest preferred level of 40 holes per 17.5 mm width, the loss of tensile strength was only around 25%.