MULTI-SHEET FILTER FOR A SMOKING ARTICLE

Abstract

A filter for a smoking article. The filter includes two or more filter substrate sheets, wherein each filter substrate sheet is folded individually such that the two or more filter substrate sheets are disposed adjacent to each other within the filter and are not layered with respect to each other.

Claims

1. A filter for a smoking article, comprising two or more filter substrate sheets, wherein each filter substrate sheet is folded individually such that the two or more filter substrate sheets are disposed adjacent to each other within the filter.

2. The filter of claim 1, further comprising three or more filter substrate sheets disposed adjacent to each other within the filter.

3. The filter of claim 1, wherein the two or more filter substrate sheets are not layered with respect to each other.

4. The filter of claim 2, wherein the three or more filter substrate sheets are not layered with respect to each other.

5. The filter of claim 1, wherein each filter substrate sheet has a basis weight of 3-35 gsm.

6. The filter of claim 5, wherein each filter substrate sheet has a basis weight of 5-20 gsm.

7. The filter of claim 6, wherein each filter substrate sheet has a basis weight of 8-13 gsm.

8. The filter of claim 2, wherein each filter substrate sheet has a basis weight of 3-35 gsm.

9. The filter of claim 8, wherein each filter substrate sheet has a basis weight of 5-20 gsm.

10. The filter of claim 9, wherein each filter substrate sheet has a basis weight of 8-13 gsm.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0009] Advantages of embodiments of the present invention will be apparent from the following detailed description of the exemplary embodiments. The following detailed description should be considered in conjunction with the accompanying figures in which:

[0010] FIG. 1 shows an exemplary filter as generally known in the prior art.

[0011] FIG. 2 shows an exemplary filter according to the embodiments disclosed herein.

[0012] FIG. 3 shows an exemplary method of forming a filter according to the embodiments disclosed herein.

[0013] FIG. 4 shows an exemplary manufacturing apparatus for forming a filter according to the embodiments disclosed herein.

DETAILED DESCRIPTION

[0014] Aspects of the invention are disclosed in the following description and related drawings directed to specific embodiments of the invention. Those skilled in the art will recognize that alternate embodiments may be devised without departing from the spirit or the scope of the claims. Additionally, well-known elements of exemplary embodiments of the invention will not be described in detail or will be omitted so as not to obscure the relevant details of the invention. Further, to facilitate an understanding of the description discussion of several terms used herein follows.

[0015] As used herein, the word exemplary means serving as an example, instance or illustration. The embodiments described herein are not limiting, but rather are exemplary only. It should be understood that the described embodiment are not necessarily to be construed as preferred or advantageous over other embodiments. Moreover, the terms embodiments of the invention, embodiments or invention do not require that all embodiments of the invention include the discussed feature, advantage or mode of operation.

[0016] According to at least one exemplary embodiment, a smoking article filter and a method of forming a smoking article filter are disclosed.

[0017] FIG. 1 shows a prior art smoking article filter 10, formed by folding and crimping a single sheet 12 of substrate material, such as, for example, paper or similar material, and inserting the folded and crimped sheet 12 into a wrapper 14 of a certain diameter. As a result of the folding and crimping, numerous channels 18 are created between folds 16 of the sheet. Large variability in the size and concentration of channels 18 can be seen in FIG. 1.

[0018] In a smoking article filter according to the present embodiments, the number and, consequently, the density of folds and channels in a transverse cross-sectional area of the smoking article filter is maximized. Increasing the density of folds and channels can result in a higher consistency of the pressure drop parameters of the filter, as well as a lower variability in the size and distribution of the channels.

[0019] In order to provide the necessary number and density of folds and channels, the amount of substrate material needs to be more densely packed within the wrapper, thereby requiring an increased amount of substrate material. This may present several challenges during the manufacturing process. One such challenge is the width of the sheet material that is being used for filter production. Prior to manufacturing, the substrate material is typically wound on bobbins, from which it is then unwound and fed into a filter manufacturing apparatus. Large substrate sheets require bobbins of commensurate size; at substrate widths over 300 mm, the increased mass of the bobbin would present issues due to high inertia while unwinding, thereby significantly limiting the linear speed of the substrate during filter production. Another challenge is that crimping rollers, through which the substrate typically passes in order to be imprinted or embossed with desired features, would likewise be heavy and difficult to produce at widths larger than 300 mm.

[0020] Furthermore, such limitations in width result in a need to increase the basis weight of the substrate material that is used for production of filters wherein a certain level of pressure drop is desired. In practice, it is preferred to use a substrate having the lowest possible basis weight, which can provide a more consistent smoking experience, similar to a cellulose acetate filter. However, a single sheet of substrate having a low basis weight cannot adequately fill a 7.8 mm (i.e., king size) filter tip. Such a filter tip filled with a single sheet of low-basis-weight substrate would result in a lower than desired pressure drop, a lower hardness, and unsatisfactory performance when air is drawn through the filter tip.

[0021] The inventors have found that including a plurality of, or at least two, substrate sheets in a smoking article filter provides improved consistency and pressure drop characteristics to the filter. Each substrate sheet can be folded and crimped individually, and subsequently inserted together into the wrapper of the smoking article filter. The inventors have further found that providing at least two substrate sheets for manufacturing a smoking article filter allows for the use of substrate sheets having a lower gsm than would be required if only a single sheet was used for manufacturing the smoking article filter. Furthermore, the use of at least two substrate sheets for manufacturing a smoking article filter allows for the use of separate bobbins for each sheet, thereby allowing the bobbins to be unwound at higher speeds and increasing the rate of filter production.

[0022] The inventors have further found that the advantageous characteristics of a smoking article filter formed from at least two substrate sheets are only present if the sheets are folded and crimped separately and subsequently inserted together into the wrapper of the smoking article filter. In other words, the substrate sheets are not layered, but are rather disposed adjacent to each other within the filter. In contrast, using a substrate sheet having multiple layers (i.e., a multiple-ply substrate sheet or multiple substrate sheets layered analogous thereto) to manufacture a smoking article filter provides a filter having characteristics similar to a filter using a single sheet of substrate material. In such filters, no improvement in the number of channels, the consistency and positions and sizes of the channels, nor the consistency of the pressure drop is obtained.

[0023] FIG. 2 shows an exemplary embodiment of a smoking article filter 100 having a plurality of filter substrate sheets 102 disposed within a wrapper 104. In the exemplary embodiment, three filter substrate sheets 102 are provided for the filter 100; however, to obtain the desired characteristics described herein, the number of substrate sheets may be at least two. Any number of substrate sheets above two that enable filter 100 to function as described herein may be contemplated and provided is desired. The specific number of substrate sheets may be selected as desired based on several factors such as a desired pressure drop, sheet width, length and diameter of the filter, as well as other variables that may depend on requirements of a specific brand or model of smoking article.

[0024] Each filter substrate sheet 102 is folded and/or crimped individually. Subsequently, the separate folded and/or crimped filter sheets are brought together to form the filter rod, which is then enclosed by wrapper 104 and subdivided into individual filters as desired.

[0025] According to the exemplary embodiments, each filter substrate sheet 102 may be obtained from a large substrate sheet 101, by slitting the large substrate sheet 101 into two, three, or more filter substrate sheets 102. The large substrate sheet 101 may have a width of 250-700 mm, or, more optimally, 450-600 mm. From this large substrate sheet 101 the filter substrate sheets 102 having lower width are obtained. The resulting widths of the filter substrate sheets 102 may then depend on both the width of the large substrate sheet 101, as well as the number of filter substrate sheets 102 obtained therefrom. For example, when a large substrate sheet 101 is split into two filter substrate sheets 102, each filter substrate sheet 102 may have a width of 125-350 mm, or, more optimally, 225-300 mm. As another example, when a large substrate sheet 101 is split into three substrate sheets 102, each s filter substrate sheet 102 may have a width of 83-233 mm, or, more optimally, 150-200 mm.

[0026] Each filter substrate sheet 102 may further have a basis weight of 3-35 gsm, more optimally 5-20 gsm, or, more optimally, 8-13 gsm.

[0027] A filter 100 having two or more filter substrate sheets 102 may have an increased number of folds 106 and channels 108 with respect to a prior art filter. For example, the number of folds and channels in a filter according to the present embodiments may be double, or more than double, than the amount of folds and channels in a prior art filter. Additionally, the CV of a filter according to the present embodiments may be reduced by at least 50% compared to a prior art filter. The number of filter sheets 102 within a filter 100, as well as gsm and width of the sheets, may be correlated with the number of folds 106 and channels 108 within the filter 100. These values may be varied and optimized as needed to achieve a desired pressure drop across the filter 100.

[0028] FIG. 3 shows an exemplary method 200 of forming a smoking article filter according to the embodiments disclosed herein. At step 202, two or more substrate sheets are provided. At step 204, each substrate sheet may be folded and/or crimped to provide a folded sheet having a plurality of folds and channels. At step 206, the two or more folded substrate sheets may be combined so as to form a continuous filter rod. At step 208, the filter rod may be enclosed in a wrapper, and, subsequently, at step 210, the filter rod may be cut into individual filter portions as desired.

[0029] FIG. 4 shows an exemplary apparatus 300 for forming a filter 100 according to the embodiments disclosed herein. In the exemplary embodiment, one or more large substrate sheets 101 may be provided on rollers and unwound therefrom by a corresponding unwinding module 310. The large substrate sheets 101 may then pass into splicing module wherein they are spliced together to form a single large substrate sheet 101. Subsequently, the large substrate sheet 101 may be split into two or more filter substrate sheets 102 by splicing knives 332. The two or more filter substrate sheets 102 then pass into the crimpling module 330, where each substrate sheet 102 is individually folded and/or crimped. Filter substrate sheets 102 then pass toward filter rod making machine 340, wherein the filter substrate sheets 102 are used to form filter 100 according to the embodiments described herein.

[0030] Table 1 shows experimental results for filters formed according to the embodiments disclosed herein, while Table 2 shows experimental results for comparative prior art filters. The filters used to obtain the results in Table 1 was formed from three separate substrate sheets, each having a basis weight of 13 gsm. The filters used to obtain the results in Table 2 was formed from a single substrate sheet having a basis weight of 18 gsm. As can be seen from the experimental results, the filters according to the present embodiments show an almost 40% improvement in variability of the pressure drop (a CV of 1.94% for the present filters vs 3.00% for the prior art filters) in cases the pressure drop is the same. Furthermore, the prior art filters can present an even higher variability, as the only way to increase the pressure drop in the prior single-sheet filters is by using a higher-basis-weight paper, which results in increased variability due use of stiffer paper.

TABLE-US-00001 TABLE 1 Results for 10 example filters made from 3 sheets, with a target length of 120.0 mm and target diameter of 7.60 mm. Basis Weight D.sub.1 D.sub.2 O.sub.1 O.sub.2 m PD Hardness Sheets (gsm) (mm) (mm) (mm) (mm) (g) (mmWG) (%) Example 1 3 13 7.63 7.63 0.51 0.51 1.223 290.00 94.00 Example 2 3 13 7.63 7.63 0.40 0.44 1.219 290.00 94.00 Example 3 3 13 7.62 7.62 0.50 0.55 1.225 289.00 94.00 Example 4 3 13 7.63 7.63 0.56 0.52 1.233 301.00 94.00 Example 5 3 13 7.64 7.64 0.43 0.48 1.225 301.00 94.00 Example 6 3 13 7.65 7.64 0.53 0.53 1.228 291.00 94.00 Example 7 3 13 7.63 7.63 0.44 0.50 1.202 295.00 94.00 Example 8 3 13 7.65 7.64 0.43 0.52 1.198 290.00 94.00 Example 9 3 13 7.62 7.63 0.42 0.49 1.215 299.00 94.00 Example 10 3 13 7.63 7.63 0.51 0.56 1.230 304.00 94.00 Min 7.62 7.62 0.40 0.44 1.20 289.00 Average PD: Max 7.65 7.64 0.56 0.56 1.23 304.00 295.00 Sdev 0.01 0.01 0.05 0.03 0.01 5.73 MAX-Min 0.03 0.02 0.16 0.12 0.04 15.00 CV: 1.94%

TABLE-US-00002 TABLE 2 Results for 10 comparative example filters made from 1 sheet, with a target length of 120.0 mm and target diameter of 7.60 mm. Basis Weight D.sub.1 D.sub.2 O.sub.1 O.sub.2 m PD Hardness Sheets (gsm) (mm) (mm) (mm) (mm) (g) (mmWG) (%) Comparative 1 18 7.50 7.50 0.44 0.45 0.856 189.00 89.30 Example 1 Comparative 1 18 7.49 7.50 0.44 0.46 0.875 196.00 89.30 Example 2 Comparative 1 18 7.48 7.47 0.44 0.33 0.862 186.00 89.30 Example 3 Comparative 1 18 7.50 7.48 0.31 0.39 0.868 180.00 89.30 Example 4 Comparative 1 18 7.49 7.50 0.41 0.41 0.860 182.00 89.30 Example 5 Comparative 1 18 7.52 7.52 0.38 0.34 0.870 187.00 89.30 Example 6 Comparative 1 18 7.49 7.49 0.41 0.46 0.870 190.00 89.30 Example 7 Comparative 1 18 7.47 7.47 0.56 0.58 0.854 185.00 89.30 Example 8 Comparative 1 18 7.47 7.47 0.50 0.51 0.852 176.00 89.30 Example 9 Comparative 1 18 7.47 7.47 0.54 0.56 0.845 187.00 89.30 Example 10 Min 7.47 7.47 0.31 0.33 0.85 176.00 Average PD: Max 7.53 7.51 0.58 0.58 0.88 196.00 185.80 Sdev 0.03 0.02 0.07 0.08 0.01 5.57 MAX-Min 0.05 0.04 0.25 0.25 0.03 20.00 CV: 3.00%

[0031] An additional advantage of a filter according to the embodiments disclosed herein is that, when used in heat-not-burn smoking articles, such a filter provides significantly more cooling of the effluent smoke due to the increased surface area, folds, and channels. The cooling characteristics of the smoke and the effect to the user are therefore improved.

[0032] The foregoing description and accompanying figures illustrate the principles, preferred embodiments and modes of operation of the invention. However, the invention should not be construed as being limited to the particular embodiments discussed above. Additional variations of the embodiments discussed above will be appreciated by those skilled in the art.

[0033] Therefore, the above-described embodiments should be regarded as illustrative rather than restrictive. Accordingly, it should be appreciated that variations to those embodiments can be made by those skilled in the art without departing from the scope of the invention as defined by the following claims.