Efficiently producible cigarette paper for self-extinguishing cigarettes

Abstract

A cigarette paper is disclosed that has at least one treated area to which a composition that contains filler particles or a mixture of filler particles is applied. The diffusion capacity thereby in the at least one treated area is less than in an untreated area of the cigarette paper, wherein at least 20% by weight, preferably at least 50% by weight and particularly preferably at least 70% by weight of the filler particles in the treated area are formed by a filler with a flaked shape or a filler with a cubic shape. Additionally or alternatively, a filler with a scalenohedral or rhombohedral crystal structure can be used, as long as the particle size distribution is selected appropriately.

Claims

1. Cigarette paper that has at least one treated area to which a composition that contains filler particles or a mixture of filler particles is applied, wherein the diffusion capacity in the at least one treated areameasured after heating the cigarette paper to 230 C. for 30 min in atmospheric air, subsequent cooling and conditioning in accordance with ISO 187:1990is smaller by a factor between 2 and 4 than in an untreated area of the cigarette paper and is larger than 0.1 and less than 1 cm/s, wherein at least 50% by weight of the filler particles in the applied composition are formed by calcium carbonate with a flaked shape.

2. Cigarette paper according to claim 1, wherein the calcium carbonate filler particle with flaked shape have a median size d.sub.50 of at least 0.3 m, and a median size of at most 5 m.

3. Cigarette paper according to claim 2, wherein the calcium carbonate with a flaked shape has a median size d.sub.50 of at least 0.5 m, and at most 5 m.

4. Cigarette paper according to claim 1, wherein the following holds for the particle size distribution of the calcium carbonate with a flaked shape: p0.5 and p1.0.

5. Cigarette paper according to claim 1, wherein the calcium carbonate particles with a flaked shape have a length (l), a width (b) and a thickness (d), that correspond to the respective maximum dimensions in three spatial directions mutually orthogonal to each other, wherein the length (1) as well as the width (b) are at least twice as large as the thickness (d).

6. Cigarette paper according to claim 1, wherein the filler is formed by precipitated calcium carbonate.

7. Cigarette paper according to claim 6, wherein said precipitated calcium carbonate is calcite.

8. Cigarette paper according to claim 1, wherein the composition contains a material that is capable of reducing its diffusion capacity upon application to a cigarette paper selected from a group consisting of starch, starch derivatives, cellulose, cellulose derivatives, dextrins, guar or gum Arabic and alginates.

9. Cigarette paper according to claim 1, wherein the amount of material applied in the treated areas, given as mass/applied area in the dried state, is at least 0.5 g/m.sup.2 and at most 12 g/m.sup.2.

10. Cigarette paper according to claim 1, wherein the at least one treated area is disposed on a wire side of the cigarette paper.

11. Cigarette paper that has at least one treated area to which a composition that contains filler particles or a mixture of filler particles is applied, wherein the diffusion capacity in the at least one treated areameasured after heating the cigarette paper to 230 C. for 30 min in atmospheric air, subsequent cooling and conditioning in accordance with ISO 187:1990is smaller by a factor between 5 and 8 than in an untreated area of the cigarette paper and is larger than 0.1 cm/s and less than 1 cm/s, wherein at least 50% by weight of the filler particles in the applied composition are formed by a filler with cubic shape.

12. Cigarette paper according to claim 11, wherein the following holds for the particle size distribution of the filler with a cubic shape: p0.2 and p0.7.

13. Cigarette paper according to claim 11, wherein the filler particles with cubic shape are formed by calcium carbonate, titanium dioxide, magnesium oxide, magnesium hydroxide or aluminum hydroxide.

14. Cigarette paper that has at least one treated area to which a composition that contains filler particles or a mixture of filler particles is applied, wherein the diffusion capacity in the at least one treated areameasured after heating the cigarette paper to 230 C. for 30 min in atmospheric air, subsequent cooling and conditioning in accordance with ISO 187:1990is smaller by a factor between 3 and 6 than in an untreated area of the cigarette paper and is larger than 0.1 cm/s and less than 1 cm/s, wherein at least 50% by weight of the filler particles in the applied composition are formed by a filler with a scalenohedral crystal structure and with a particle size distribution, for which the following holds: p0.8, or p0.3.

15. Cigarette paper that has at least one treated area to which a composition that contains filler particles or a mixture of filler particles is applied, wherein the diffusion capacity in the at least one treated areameasured after heating the cigarette paper to 230 C. for 30 min in atmospheric air, subsequent cooling and conditioning in accordance with ISO 187:1990is smaller by a factor of less than 5 than in an untreated area of the cigarette paper and is larger than 0.1 cm/s and less than 1 cm/s, wherein at least 50% by weight of the filler particles in the applied composition are formed by a filler with a rhombohedral crystal structure and with a particle size distribution for which the following holds: p0.6.

16. Process for producing a cigarette paper with the following steps: producing a base paper, and treating at least one area of the base paper with a composition that contains filler particles or a mixture of filler particles in order to reduce the diffusion capacity in the treated area compared with the diffusion capacity of the base cigarette paper, by a factor between 2 and 4, to a value that is larger than 0.1 and less than 1 cm/s, wherein the diffusion capacity is measured after heating the cigarette paper to 230 C. for 30 min in atmospheric air and subsequently cooling and conditioning the cigarette paper in accordance with ISO 187:1990, and wherein at least 50% by weight of the filler particles in the composition are formed by calcium carbonate with a flaked shape.

17. Process according to claim 16, wherein the composition contains a material that is capable of reducing the diffusion capacity of cigarette paper upon application to the cigarette paper, the material is selected from the group consisting of starch, starch derivatives, cellulose, cellulose derivatives, dextrins, guar or gum Arabic and alginates.

18. Process according to claim 16, wherein the composition contains a solvent that can form a solution or suspension with a material that is capable of reducing the diffusion capacity upon application to the cigarette paper.

19. Process according to claim 17, with the following steps: producing a first amount of a preliminary composition that contains a solvent and a material that is capable of reducing the diffusion capacity of the cigarette paper, removing a first part of the preliminary composition, adding the filler particles containing the calcium carbonate with a flaked shape to the removed first part of the preliminary composition in order to form a first composition, and treating areas of the base paper with the first composition.

20. Process according to claim 19, wherein the addition of fillers to the removed part of the preliminary composition is carried out in an application apparatus or in a pipe feeding to the application apparatus for the application of the preliminary or first composition, respectively.

21. Process according to claim 16, wherein the composition is applied by a printing process, wherein the composition preferably has a flow time of at least 10 s and at most 35 s, measured with a flow cup with a 4 mm opening in accordance with EN ISO 2431:2001 at a temperature of the composition of 60 C., or is applied by a spraying process.

22. Process according to claim 16, wherein the cigarette paper is re-wetted after the application of the composition and subsequently dried under mechanical load in order to avoid wrinkles in the cigarette paper, wherein the composition preferably contains substances to reduce the formation of wrinkles, in particular propylene glycol or glycerin.

23. Cigarette with a cigarette paper that wraps a tobacco column, wherein the cigarette paper is a cigarette paper according to claim 1.

24. Cigarette according to claim 23, wherein the filler, respectively, in the composition is selected such that the cigarette extinguishes with a probability of at least 75% in a test in accordance with ISO 12863:2010, but during smoldering in air smolders over the entire length of its tobacco column with a probability of at least 50% without self-extinguishing.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows, for scalenohedral fillers, the relationship between the dimensionless distribution parameter p of the particle size distribution and the diffusion capacity.

(2) FIG. 2 shows, for rhombohedral fillers, the relationship between the dimensionless distribution parameter p of the particle size distribution and the diffusion capacity.

(3) FIG. 3 is a schematic drawing of a flaked calcium carbonate particle, for which the length l, the width b and the thickness d are shown.

(4) FIG. 4 shows a table with diffusion capacities and viscosity values for various filler types when using a first base paper A.

(5) FIG. 5 shows a table with diffusion capacities for various filler types when using a second base paper B.

EXAMPLES

(6) For a better understanding of the present invention it is illustrated below in some examples.

(7) The composition applied to the paper is an aqueous composition consisting of 13% by weight oxidized starch, 0.5% by weight cationic starch and 6% by weight chalk as filler. The composition was produced according to the manufacturer's instructions. In total, 13 different fillers were selected in accordance with FIG. 4 and one of the fillers was each dispersed in the composition.

(8) The flow time of the composition as a measure of the viscosity was determined with a flow cup with an opening of 4 mm in accordance with the standard represented by ONORM EN ISO 2431:2011 at a temperature of the composition of 60 C. and is shown in FIG. 4.

(9) The composition was applied to two different cigarette papers A and B. Before application of the composition, cigarette paper A had a basis weight of 25 g/m.sup.2, an air permeability in accordance with ISO 2965 of 70 cm.Math.min.sup.1.Math.kPa.sup.1, a filler content of 33% by weight and a content of 1% by weight tri-potassium citrate as burn additive, while cigarette paper B had a basis weight of 24 g/m.sup.2, an air permeability in accordance with ISO 2965 of 75 cm.Math.min.sup.1.Math.kPa.sup.1, a filler content of 29% by weight and a content of 2% by weight tri-potassium citrate as burn additive. To simulate the thermal decomposition of the cigarette paper during smoking, the cigarette paper was stored in a heating cabinet, pre-heated to 230 C., for 30 minutes in an atmosphere of air, and then it was removed from the heating cabinet and conditioned in accordance with ISO 187:1990. The measurement of diffusion capacity was then carried out in accordance with CORESTA Recommended Method No. 77 with a Diffusivity Tester (Borgwaldt A50) manufactured by Borgwaldt KC GmbH of Hamburg, Germany.

(10) Without application of the composition, after the above heating process, both cigarette papers had an average diffusion capacity of 2.17 cm/s calculated from 10 individual values.

(11) The application of the composition was carried out by means of a roto-gravure printing station in accordance with the prior art in one layer on the wire side of the original, that is not heat-treated, cigarette paper, in the shape of 6 mm wide bands oriented in the cross-direction of the paper with a distance from band centre to band centre of 27 mm. After application, the paper was dried.

(12) In similar manner to that described above for the measurement of the diffusion capacity of the cigarette paper without application of the composition, the paper, now with the composition applied to it, was stored in a heating cabinet, pre-heated to 230 C., for 30 minutes in an atmosphere of air, then it was removed from the heating cabinet and conditioned in accordance with ISO 187:1990. The measurement of diffusion capacity was then carried out in accordance with CORESTA Recommended Method No. 77 with a Diffusivity Tester (Borgwaldt A50) manufactured by Borgwaldt KC GmbH of Hamburg, Germany, each on 10 different positions. The mean values of the diffusion capacities are shown in tables 1 and 2 of FIGS. 4 and 5.

(13) The ratio of the mean values of the diffusion capacities of the untreated cigarette paper and the treated areas is given in table 1 of FIG. 4 for paper A and in table 2 of FIG. 5 for paper B, each in the column Ratio.

(14) The geologically sourced and ground chalk of examples 8 and 23 serves as a point of reference.

(15) It can be seen firstly from examples 1 and 15 that an extraordinarily high diffusion capacity can be achieved with flaked calcite. The use of such types of filler causes a decrease of the diffusion capacity by a factor between 2 and 4 compared with that of the untreated cigarette paper. On the contrary, with a cubic calcite, examples 13 and 25, a very low diffusion capacity and correspondingly a decrease of the diffusion capacity compared with that of the untreated cigarette paper by a factor 5 to 8 is obtained.

(16) The scalenohedral and rhombohedral calcites of the remaining examples provide mostly diffusion capacities in the median range.

(17) In FIG. 1 the values of the distribution parameter p and the diffusion capacities for papers, to which a composition with a scalenohedral filler has been applied, are shown graphically, that is, for examples 3, 4, 6, 9-11, 16-18, 21, 22 and 24 as a round dot, and for examples 12 and 26, for which the filler also contains aragonite in addition to calcite, as a small square. It can clearly be seen that for low values of p, for example, p<0.3, as well as for high values of p, for example, p>0.7, a high diffusion capacity can be obtained. In these ranges for the parameter p, the diffusion capacity is reduced by factor 3 to 6 compared with the untreated cigarette paper. For values of p between 0.3 and 0.7, low diffusion capacities and correspondingly a decrease of the diffusion capacity by a factor greater than 6 are obtained. The line in FIG. 1 shows the curve p(p1)+0.6 cm/s and illustrates the good correlation of this parameter with the diffusion capacity. The correlation coefficient is greater than 0.94.

(18) Examples 12 and 26 show a mixture of calcite and aragonite, with primarily scalenohedral crystal structure. The data are shown as a small square in FIG. 1 and fit well into the picture for scalenohedral fillers.

(19) In FIG. 2, the values for the distribution parameter p and the diffusion capacities for papers to which a composition with a rhombohedral filler has been applied are shown graphically, that is, for examples 2, 5, 7, 14, 19 and 20. It can clearly be seen that for low values of p, for example, p<0.5, a low diffusion capacity can be obtained and thereby a reduction of the diffusion capacity by a factor of more than about 5 compared with the untreated cigarette paper, while for values of p>0.5, high diffusion capacities, that is a reduction by a factor of less than about 5, are obtained. The line in FIG. 2 shows the curve 3p(p0.6)+0.7 in cm/s and illustrates the good correlation of this parameter with the diffusion capacity. The correlation coefficient is greater than 0.98. Whether rhombohedral fillers also exhibit an increase in the diffusion capacity for particularly low values of the distribution parameter p or not cannot be determined reliably from the data. The skilled person is capable of determining this by simple experimentation, however.

(20) The rows in tables 1 and 2 of FIGS. 4 and 5 are ranked in descending order. It can also be seen by comparing the first and second column of FIG. 5 that the order of the chalk types remains approximately the same. Since the examples of tables 1 and 2 of FIGS. 4 and 5 differ only with respect to the cigarette paper, it turns out that the invention can be used essentially independently of the cigarette paper.

(21) In addition, the flow time of the composition, as indicated in table 1 of FIG. 4, should be noted. The flow time is a measure of the viscosity and in all examples is in the relatively narrow interval from 14.3 s to 16.5 s, so that without further adjustments to the process parameters, all compositions can be processed in the same way. Thus, the advantage of a quick adjustment of the diffusion capacity can be employed for small production batches and, depending on the process, without substantial time delay when changing the diffusion capacity.

(22) A particular advantage of the invention, as mentioned above, consists in the fact that the diffusion capacity can be influenced without changing the process parameters or the chemical composition of the composition to be applied, simply by selection of an appropriate crystal structure, shape or size of the filler particles.

(23) The invention can be realized in the following process in a particularly advantageous manner.

(24) Firstly, a cigarette paper is provided to which the composition is to be applied in areas.

(25) In a next step, a preliminary composition is produced, comprising at least the solvent and a material for reducing the diffusion capacity, but at most negligible amounts of the fillers according to the invention. This can preferably be carried out in a receiver tank.

(26) In the case of a starch or a starch derivative, this step can comprise suspending the starch or the starch derivative in water, heating the suspension and maintaining it at an elevated temperature then cooling. All these steps can be carried out while stirring this preliminary composition.

(27) In general, the preliminary composition can be produced according to the instructions of the manufacturer of the material that reduces the diffusion capacity.

(28) The next step consists in selecting the type of filler particle based on the intended diffusion capacity of the treated areas on the cigarette paper.

(29) Here again, the starting point for the following considerations is the diffusion capacity of the areas of a cigarette paper that is treated in areas with a composition that contains, as filler, a geologically sourced chalk with a median particle size of about 2.38 m. Terms like high, higher, low, lower or middle in relation to the diffusion capacity should be understood to be with respect to this point of reference.

(30) To obtain a high diffusion capacity, one selects, for example, a flaked calcium carbonate filler. Preferably, the distribution parameter p=d.sub.50/(d.sub.90d.sub.10) should be at least 0.5, preferably at least 0.6 and at most 1.0, preferably at most 0.9.

(31) In order to obtain a low diffusion capacity, a cubic filler is preferably selected. Preferably, the distribution parameter p=d.sub.50/(d.sub.90d.sub.10) should be at least 0.2, preferably at least 0.3 and at most 0.7, preferably at most 0.6.

(32) In order to adjust the diffusion capacity in a median range more precisely, a filler with a scalenohedral crystal structure that leads to the desired diffusion capacity with respect to its distribution parameter p=d.sub.50/(d.sub.90d.sub.10) can preferably be used. For high diffusion capacities in the median range, a filler with a value for p of greater than 0 and less than or equal to 0.3, preferably less than or equal to 0.25 and particularly preferably less than or equal to 0.2 will be selected, or alternatively a filler with a value of p0.7, preferably 0.8, particularly preferably 0.85 and in particular 0.9. However, in this regard, p should be 1.2, preferably 1.0. For low diffusion capacities in the median range, the distribution parameter p for the scalenohedral filler will be selected so as to be 0.3, preferably 0.4 and 0.7, preferably 0.6. To reduce the diffusion capacity, the range 0.45p0.55 can be used.

(33) Alternatively, in order to adjust the diffusion capacity in the median range, a filler with a rhombohedral crystal structure that leads to the desired diffusion capacity with respect to its distribution parameter p=d.sub.50/(d.sub.90d.sub.10) can also be used. For high diffusion capacities in the median range, a filler with a value of p0.5, preferably 0.6 and particularly preferably p0.7 and preferably less than 1.0, preferably less than 0.8 will be selected. For low diffusion capacities in the median range, the distribution parameter p of the rhombohedral filler will be selected to be 0.1, preferably 0.2 and 0.5, preferably 0.4.

(34) With respect to the type of filler, the indications given above are advantageously taken into consideration. Calcium carbonate is preferred and calcite is particularly preferred.

(35) The next step consists in dispersing the filler in the preliminary composition. In this regard, it is essential for the invention that the filler is not added, as is usually the case, to the entire preliminary composition produced in the first step, but only to a part thereof. The amount of filler added to this part of the preliminary composition results from the corresponding desired filler content in the finished composition. This allows for the production of smaller amounts of the finished composition, so that smaller batches of paper can be produced. Furthermore it allows for a quick and trouble-free change of the diffusion capacity by changing the filler, without having to produce the preliminary composition anew.

(36) Dispersing the filler in a part of the preliminary composition can be carried out in various ways.

(37) For example, it is possible to transfer firstly a part of the preliminary composition, for example, by pumping into a further tank and to add the corresponding amount of filler there and to disperse it, for example, by stirring.

(38) Alternatively and preferably, it is also possible to disperse the filler firstly in a solvent, for example, by stirring, wherein preferably, the same solvent is used as for the preliminary composition, and then to add the filler suspension to the preliminary composition while the latter is being transferred to the application apparatus. This is preferred because fillers are often produced or are commercially available as aqueous suspensions (slurry) and not as dry powder.

(39) The preliminary composition can, for example, be pumped in a pipe from the receiving tank to the application apparatus and the filler suspension is added in the required amount, preferably by pumping, to the same pipe. Particularly preferred thereby is a process in which the flow in the tube is turbulent and thereby mixing of the filler suspension with the preliminary composition occurs as quickly as possible. In a particular advantageous manner, this process can then be used if the dead volume of lines, tanks and devices up to application of the composition to the paper is as small as possible. This can be the case, for example, when application is by means of a spraying process. In this manner, a change of the type of filler can have an effect on the diffusion capacity of the treated areas on the cigarette paper in a very short time, for example, without stopping the application apparatus.

(40) In the following step, the finished composition is transferred to the application apparatus and applied to areas of the paper. The usual processes such as printing processes, in particular roto-gravure printing and flexographic printing, or spraying processes are available for this purpose. Then the paper is dried.

(41) To remove wrinkles that occur when applying aqueous compositions, the aforementioned processes can be used.

(42) In a further embodiment of the process according to the invention, the diffusion capacity of the treated areas can be adjusted further by automatically adapting the mixing ratio of two or more different fillers.

(43) Firstly, the diffusion capacity of the areas of the cigarette paper is measured. This can be carried out by sampling, off-line, on a separate measuring device, for example a Diffusivity Tester (Borgwaldt A50) manufactured by Borgwaldt KC GmbH of Hamburg, Germany, in accordance with CORESTA Recommended Method No. 77, or in the running application apparatus, that is, on-line. Since a direct on-line measurement of diffusion capacity is difficult, it can be estimated from other parameters, for example, transmission, absorption or reflection of electro-magnetic radiation. Such estimation can be carried out with image-analysis tools, for example, based on the transparency of the paper to electro-magnetic waves with a wave length of at least 100 nm and at most 500 nm. This can be done by comparing the intensity of a reference beam of these electro-magnetic waves that does not pass through the paper with the intensity of a beam that passes through the paper. The higher the diffusion capacity and hence the pore volume of the paper, the lower will be the attenuation of the beam compared with the reference beam. This comparison of the intensities has to be synchronized with the presence of treated areas in the operational area of the sensor.

(44) The measured value obtained is then compared with a target value and the difference transferred to an actuator that changes the ratio of the amount of fillers added to the preliminary composition. For example, the proportion of cubic calcite will be decreased and the proportion of flaked calcite increased if too low a diffusion capacity is measured and it is desired to increase the diffusion capacity. For a diffusion capacity which is too high, the reverse procedure is followed. This can, for example, be carried out by adjusting the flow rates with a flow controller. Preferably the proportion is adjusted in a manner such that the entire amount of filler in the composition does not change.

(45) Entirely analogously this process can, of course, also be carried out with a mixture of two or more fillers of different shape or crystal structure, for example, cubic and scalenohedral, or flaked and rhombohedral, or cubic, scalenohedral and flaked, or cubic, rhombohedral and flaked.

(46) Finally, in one embodiment of the invention, two scalenohedral fillers can also be used, which differ sufficiently with the distribution parameter p=d.sub.50/(d.sub.90d.sub.10) having regard to the value p(p1). Preferably, a filler with a value of p of greater than 0 and 0.3, preferably 0.2 will be selected and combined with a filler with a value of p0.3, preferably 0.4 and 0.7, preferably 0.6. Alternatively, a filler with a value of p0.7, preferably 0.8 and 1.2, preferably 1.0 will be selected and combined with a filler with a value of p0.3, preferably 0.4 and 0.7, preferably 0.6.

(47) Similarly, in an embodiment of the invention two rhombohedral fillers can be used that differ sufficiently with respect to the value p(p0.6) with the distribution parameter p=d.sub.50/(d.sub.90d.sub.10). Preferably, a filler with a value of p0.1, preferably 0.2 and 0.5, preferably 0.4 will be selected and combined with a filler with a value of p0.5, preferably 0.6 and 1.0, preferably 0.8.

(48) For flaked calcium carbonate particles, a filler with a distribution parameter p=d.sub.50/(d.sub.90d.sub.10) from at least 0.5, preferably at least 0.6 to at most 1.0, preferably at most 0.9 can preferably be selected.

(49) For cubic filler particles, a filler with a distribution parameter p=d.sub.50/(d.sub.90d.sub.10) from at least 0.2, preferably at least 0.3, to at most 0.7, preferably at most 0.6 can preferably be selected.

(50) The principle in this respect is that always, independently of shape, crystal structure and particle size distribution, two or more fillers are combined that result in diffusion capacities in the areas on the cigarette paper that are substantially different from each other.

(51) It is also possible to mix two or more fillers of the same shape but different particle size distribution, or even different chemical compounds using this regulation process. However, the mixture of two fillers is preferred because then the regulation process can be designed easily. The use of said mixtures is, of course, also possible without this regulation.

(52) The intervals according to this invention and the preferred intervals for the distribution parameter are generally valid for the use of filler particles with the respective shape or crystal structure irrespectively of whether the filler is used alone or in a mixture of two or more fillers.

(53) From the cigarette papers according to the invention, cigarettes can be manufactured by machine, manually or partially manually by prior art processes.