Cigarette paper that gives a cigarette a uniform drawing profile

Abstract

A cigarette paper is disclosed that contains at least one burn additive the concentration c(x) of which varies along a direction x of the cigarette paper. For the position-dependent concentration c(x) over an interval of length L, for x over the interval [0,L], (x)cc(x)(x)+c. In this regard, 3 cmL11 cm, (x) is monotonic over the interval [0,L], but not a constant function over the entire interval, and c1% by weight, preferably 0.7% by weight and particularly preferably 0.5% by weight, and especially preferably 0.3% by weight and particularly preferably 0.15% by weight and c>0% by weight, each with respect to the mass of the cigarette paper.

Claims

1. Cigarette paper comprising at least one burn additive that increases or reduces a smoldering speed of the cigarette paper, wherein: a concentration c(x) of the at least one burn additive varies along a direction x of the cigarette paper, a position-dependent concentration c(x) over an interval of length L for x over the interval [0,L] is:
(x)cc(x)(x)+c wherein: 3 cmL1 cm, f(x) is monotonic over the interval [0,L], but is not a constant function over the entire interval, c1% by weight and c0% by weight, respectively with respect to the mass of the cigarette paper, |(L)(0)|2c, the air permeability of the cigarette paper comprising the at least one burn additive is between 20 cm min.sup.1 kPa.sup.1 and 200 cm min.sup.1 kPa.sup.1, and the at least one burn additive comprises at least one of: tri-sodium citrate, tri-potassium citrate, further citrates, malates, tartrates, acetates, nitrates, succinates, fumarates, gluconates, glycolates, lactates, oxylates, salicylates, -hydroxy caprylates, or mixtures thereof.

2. Cigarette paper according to claim 1, wherein c0.7% by weight.

3. Cigarette paper according to claim 1, wherein |(L)(0)|0.5% by weight.

4. Cigarette paper according to claim 1, wherein the function f(x) is defined as: $f\left(x\right)=\{\begin{array}{cc}{c}_0& 0x{L}_1\\ c_0+\left(c_L-c_0\right)\frac{x-L_1}{L_2-L_1}& L_1<x<L_2\\ c_L& L_{2}xL\end{array}$ wherein L.sub.1 and L.sub.2 are boundaries of intervals between 0 and L, c.sub.0 is the concentration at point 0, and c.sub.L is the concentration at point L.

5. Cigarette paper according to claim 4, wherein c.sub.0 or c.sub.L are greater than or equal to 0.2% by weight and 15.0% by weight, wherein in each case c.sub.0 and c.sub.L are different from each other.

6. Cigarette paper according to claim 4, wherein L.sub.12L/3 and L.sub.1L/6.

7. Cigarette paper according to claim 4 wherein, further: L.sub.2L/3 and L.sub.25L/6, wherein L.sub.1L.sub.2 always holds.

8. Cigarette paper according to claim 4 wherein, further: L.sub.2L.sub.1L/6 and L.sub.2L.sub.19L/10.

9. Cigarette paper according to claim 1, with at least one mark, positioned on the cigarette paper in a pre-determined spatial relationship to the function c(x), wherein the mark is detectable by an optical sensor.

10. Cigarette paper according to claim 9, intended for a filter cigarette and wherein the mark is at a position that is located under the tipping paper on a filter cigarette that is manufactured therefrom or where the mark is applied to the side that is facing away from the tobacco on a finished cigarette.

11. Cigarette paper according to claim 1, wherein the described profile c(x) varies periodically, alternating in normal and reverse directions.

12. Cigarette paper according to claim 1, wherein the cigarette paper comprises pulp fibers or a mixture of pulp fibers, wherein the pulp fibers have been sourced from wood, flax, hemp or esparto grass, wherein the cigarette paper has a basis weight from 10 g/m.sup.2 to 60 g/m.sup.2.

13. Cigarette paper according to claim 1, further comprising an inorganic mineral filler, wherein the inorganic mineral filler comprises at least one of chalk, magnesium oxide, aluminum hydroxide, carbonates or mixtures thereof.

14. The cigarette paper of claim 1 wherein c0.5% by weight.

15. The cigarette paper according to claim 1, in which c0.5% by weight and |(L)(0)|2.0% per weight.

16. The cigarette paper according to claim 1, in which c0.3% by weight and |(L)(0)|1.0% per weight.

17. Process for producing a cigarette paper comprising: providing a base cigarette paper, and introducing at least one burn additive that increases or reduces a smoldering speed of the cigarette paper to arrive at the cigarette paper of claim 1.

18. Process according to claim 17, wherein c 0.7% by weight.

19. Process according to claim 17, wherein the at least one burn additive is applied to the base cigarette paper in the form of a liquid composition by a printing process or by spraying.

20. Process according to claim 19, wherein the printing process is roto-gravure printing or flexographic printing.

21. Process according to claim 20, providing a roto-gravure printing cylinder with recesses from which the composition printed is transferred to the base paper, wherein the volume of the recesses and/or the density of the recesses on the roto-gravure printing cylinder are selected such that the desired position-dependent concentration c(x) of the burn additive is obtained.

22. Process according to claim 20, wherein the flow time of the composition is 10 s to 40 s measured in accordance with NORM EN ISO 2431:2011 with a cup with an opening of 4 mm at the temperature the composition is used in the application process.

23. Process according to claim 19, wherein the content of the at least one burn additive or burn additive mixture in the composition is at least 0.1% by weight and at most 15% by weight with respect to the mass of the composition.

24. Process according to claim 19, wherein the composition contains polymers or a mixture of polymers for adjusting the viscosity, wherein the polymers are a cellulose derivative, and are chosen from a group consisting of carboxy methyl cellulose, a polysaccharide, starch or starch derivatives, an alginate, a dextrin, guar or gum Arabic or combinations thereof.

25. Process according to claim 19, wherein the applied amount of the composition per unit area corresponds to at most 80% of the corresponding initial basis weight before application of the composition.

26. Process according to claim 19, further comprising a step of drying the cigarette paper after application of the composition using one of a hot air dryer, an infra-red dryer, a tunnel dryer, by heated drying cylinders or the use of micro-waves.

27. Process according to claim 26, wherein the composition is water-based and drying is carried out by contact with one or more drying cylinders that are heated, wherein one or more spreader rollers or smoothing devices are provided configured for pulling wrinkles out of the paper during drying and arranged such that the paper runs over one or more spreader roller(s) or smoothing device(s) before the drying cylinder.

28. Process according to claim 17, wherein at least a part of the at least one burn additive is introduced by impregnation of the paper: a) in a size or film-press of a paper machine, or b) in equipment downstream of the paper machine with a solution of the burn additive.

29. Process according to claim 17, wherein the at least one burn additive is initially introduced to the paper with an approximately uniform concentration and then washed out in a position-dependent manner, in order to obtain the desired position-dependent burn additive concentration.

30. Cigarette comprising: a tobacco rod; and a cigarette paper, according to claim 1, that surrounds the tobacco rod.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a cigarette and arranged above it is a diagram of an exemplary profile of the content of the at least one burn additive.

(2) FIG. 2 shows an exemplary profile of the content of the at least one burn additive along the cigarette paper, as it results from the common machine-made cigarette production process.

DETAILED DESCRIPTION ON THE INVENTION

(3) Some examples will now demonstrate the desired effect according to the invention.

(4) Tri-sodium citrate was applied as a burn additive to a cigarette paper with a basis weight of 30 g/m.sup.2 from wood pulp, a content of precipitated chalk as filler of 30% of the paper mass and an air permeability of 50 cm min.sup.1 kPa.sup.1, according to ISO 2965.

(5) More precisely, a water-based solution of the burn additive was produced, as is also prepared for impregnation of the paper as is known in the prior art. The burn additive content in the solution resulted thereby from the desired profile of the content in the cigarette paper and the requirements of the application process.

(6) Cigarettes with the following properties were manually produced from the cigarette paper:

(7) TABLE-US-00001 Diameter 7.8 mm Length of the cigarette 84 mm Length of the filter 24 mm Filter cellulose acetate Length of the tipping paper 32 mm Filler weight of the tobacco rod 750 mg Tobacco blend American blend

(8) In this regard, firstly, long tubes of cigarette paper were prepared and cut such that the profile of the burn additive corresponded to the desired profile on a cigarette manufactured therefrom. Then the tubes were filled with tobacco and a filter plug was attached to the tube, filled with tobacco, by means of a tipping paper.

(9) For each profile of the burn additive content, 60 cigarettes were machine-smoked according to ISO 4387 and the tar and nicotine generated in each puff were collected in a Cambridge Filter Pad. Tar and nicotine were determined for each puff from the analysis of the Cambridge Filter Pad.

(10) From the content of tar and nicotine in each puff, the mean value (M) in mg over all puffs, the coefficient of variation (CoV) as a % over all puffs and the ratio V of the content between the last and first puff were calculated. The coefficient of variation in this regard is the standard deviation of the respective smoke yield over all puffs of a cigarette divided by its mean value and expressed as percentage. The profiles of the burn additive content according to the function f(x) are characterized by the parameters c.sub.0, c.sub.L, L.sub.1 and L.sub.2 and are shown in Table 1 together with the results.

(11) TABLE-US-00002 TABLE 1 Profile Tar Nicotine c.sub.0 c.sub.L L.sub.1 L.sub.2 M CoV M CoV No. % % mm mm mg % V mg % V 1 1.4 1.4 0 52 1.25 16.1 1.62 0.075 11.6 1.41 2 0.7 0.0 0 52 1.33 13.0 1.47 0.082 7.6 1.25 3 1.4 0.0 0 52 1.30 12.5 1.44 0.080 6.4 1.20 4 2.0 0.0 0 52 1.29 13.5 1.47 0.078 6.8 1.20 5 2.7 0.0 0 52 1.31 16.0 1.56 0.078 8.9 1.25 6 3.5 0.0 0 52 1.35 19.9 1.70 0.080 12.5 1.35 7 2.7 2.5 0 52 1.52 9.4 1.32 0.086 6.6 1.21 8 2.0 3.5 0 52 1.45 7.1 1.23 0.082 4.8 1.15 9 1.4 3.5 0 52 1.40 6.2 1.18 0.080 4.5 1.12 10 0.7 3.5 0 52 1.37 6.9 1.18 0.079 6.1 1.15 11 0.0 3.5 0 52 1.36 9.3 1.23 0.080 9.1 1.22 12 1.4 3.5 10 40 1.41 4.9 1.18 0.081 3.9 1.13 13 1.4 3.5 5 45 144 4.5 118 0.083 3.4 1.13

(12) Profile No. 1 corresponds to a constant burn additive content of 1.4% and serves for comparison. It can be seen by means of the ratio V that there is a significant increase in the tar content of 62% and in the nicotine content of 41%. The coefficients of variation of tar and nicotine are 16.1% and 11.6%.

(13) The profiles 2 to 6 show a burn additive content that decreases from the mouth end to the cigarette tip, while the profiles 7 to 13 correspond to an increasing burn additive content. For the profiles 12 and 13 the burn additive is constant over a length of 10 mm or 5 mm, respectively, at the mouth end and at the cigarette tip, and in between it increases linearly.

(14) It can be seen from table 1 that for the profiles 2-5 and 7-13, the coefficient of variation of the tar content as well as the ratio of the tar contents between the last and the first puff is less than for a comparative cigarette with the constant profile of example 1. As regards the nicotine content, all of the profiles 2-13 exhibited an improvement over the comparative cigarette with respect to the coefficient of variation of the nicotine content or with respect to the ratio of the nicotine content between the last and first puff.

(15) It can also be seen that for profiles 2-6, with decreasing burn additive content along the tobacco rod, only smaller improvements could be obtained than with the increasing profiles 7-11. This holds for tar as well as for nicotine. As an example, for profiles 2-6 the lowest coefficient of variation of the tar content could be obtained with 12.5% for profile 3, i.e. a decrease from 1.4% to 0% burn additive content, while the same parameter is below this value for all profiles 7-11, and reached a minimum of 6.2% for profile 9, an increase from 1.4% to 3.5% burn additive content.

(16) In this regard, the effect that a constant content of about 1.5% to 3.0% tri-sodium citrate results in a minimum for tar and nicotine values is exploited.

(17) Both profiles 2-6 decreasing in direction towards the cigarette tip, x=L, as well as profiles 7-13, increasing in this direction, exploit the effect that a burn additive content that leads to lower tar and nicotine values is present close to the filter end, where the strong puffs are generated.

(18) In comparison to the other examples, it turns out that the profiles 6 and 11 are less preferred, because for these profiles the burn additive content at the filter end, with 3.5% for profile 6 and with 0% for profile 11, deviates significantly from that burn additive content for which minimum tar and nicotine values can be obtained. For these two profiles the possibilities for stabilizing the puff profile have not been fully utilized.

(19) Generally, the burn additive content in the area of the filter end can thus almost be selected such that it leads to a minimization of a certain smoke yield, in particular tar or nicotine, for an otherwise identical cigarette with constant burn additive content, and starting from this value increases or decreases monotonically or approximately monotonically in the direction towards the cigarette tip. The term almost be selected such should also allow for deviations from the ideal value of the burn additive concentration that are less than 50%, preferably less than 30%, particularly less than 15% of the ideal value. In addition, the term otherwise identical cigarette for a cigarette means that it is produced from the same base cigarette paper or from a base cigarette paper that is similar inasmuch as the basis weight deviates by at most 20% and the mean air permeability, according to ISO 2965, deviates at most 15% from the same base cigarette paper. Particularly good results were found for the two profiles 12 and 13 for which, in addition to a linear increase from 1.4% to 3.5% burn additive content, areas with constant burn additive content of 1.4% and 3.5%, respectively, are provided on a length of 5 mm or 10 mm at the mouth end and at the cigarette tip. Although hardly any improvements can be obtained in the ratio of the tar and nicotine content between the last and the first puff compared with examples 2-11, the coefficient of variation of tar and nicotine can be further reduced and reaches values of 4.9% and 4.5% for tar and 3.9% and 3.4% for nicotine.

(20) The particularly preferred embodiment of examples 12 and 13 is shown in FIG. 1. An exemplary cigarette 100 consists of a filter 101, wrapped with a tipping paper 102 that partially overlaps the tobacco rod 103 that in turn is wrapped with a cigarette paper 104. On the cigarette 100, the tipping paper 102 is located in an overlapping zone over the cigarette paper 104. The dashed line 105 indicates the boundary between the filter and the tobacco rod, so that the overlapping zone runs from the dashed line 105 to the position x=0 along the cigarette axis. The diagram 110 arranged over the cigarette 100 in FIG. 1 shows an exemplary profile of the content of the at least one burn additive. The x-axis 111 shows the position x=0 at the start of the visible tobacco rod and the position x=L at the end of the cigarette to be lit. The y-axis 112 shows the content of the at least one burn additive. At first the content of the at least one burn additive is constant at a level c.sub.0 in the range from x=0 to x=L.sub.1, reference numeral 113, and then it increases linearly in the range from x=L.sub.1 to x=L.sub.2 from the level c.sub.0 to the level c.sub.L, reference numeral 114, and then remains at the level c.sub.L up to the position x=L, reference numeral 115. Of course, this is an idealized profile, from which deviations are possible in reality, for example by the usual production tolerances or inhomogeneities of the paper.

(21) During the machine manufacture of cigarettes, an endless tobacco rod is formed that is cut into pieces, that have the length of the tobacco rod on the cigarette. Between two such pieces a filter plug of double length is inserted and adhered to a tipping paper of double width, so that a double cigarette connected at the filter end is created. In a final cut the double cigarette is divided in two cigarettes and one of the two cigarettes is flipped over so that all cigarettes running out of the cigarette machine are identically oriented. It follows that there is a need for appropriate selection of the profile of the content of the at least one burn additive along the cigarette paper web. Such an exemplary profile is shown in FIG. 2.

(22) The main direction of the cigarette paper, typically the machine direction, is indicated by arrow 201. The direction 202 indicates the content of the at least one burn additive and its profile in the direction 201 is indicated by line 203. On the cigarette machine a piece of tobacco rod is produced by a cut at each of the positions indicated by lines 204 and 205. The area 207 delimited by the dashed lines 206 is located under the tipping paper on a double cigarette and is therefore not visible during normal use. In this area 207 the profile of the content of the at least one burn additive is not important, because this area is typically not smoked. The x-axes 208 indicate the course of the x-coordinate from position x=0 to position x=L for each of the cigarettes manufactured from the tobacco rod. Because a double cigarette is produced with a subsequent cut along the lines 204 and 205 and flipping over of the cigarette, it is necessary that along direction 201 an increasing and a decreasing profile alternate periodically, if the profile of the content of the at least one burn additive is to be permanently nominally identical in the area of the visible tobacco rod on the manufactured cigarettes.

(23) In order to synchronize cutting of the tobacco rod with the profile 203 of the content of the at least one burn additive, marks are employed at the positions indicated by lines 205, i.e. in the area 207, as the areas 207 will be overlapped by the tipping paper on the cigarette and hence the marks are not visible.

(24) Of course, this is just an exemplary profile and it is simple for the skilled person for any desired profile of the at least one burn additive on the cigarette to determine the corresponding profile on the cigarette paper web depending on the production process of the cigarette.

(25) Applying the burn additives according to the invention also brings about changes in the overall tar and nicotine content even compared to the comparative cigarette with the constant profile of example 1. These changes, however, can easily be compensated for by adjustment of the filter ventilation or the filter, without impairing the effect according to the invention.

(26) By means of these examples, the skilled person will be able to work out a profile for the content of at least one burn additive for a large class of burn additives with little experimental effort, so that the invention can easily be transferred to various burn additives. In addition, he/she will be able to work out a desired profile of the content of at least one burn additive for diverse cigarette papers and cigarette designs.