Film-forming composition for applying to cigarette paper
10349673 ยท 2019-07-16
Assignee
Inventors
Cpc classification
International classification
Abstract
The present invention relates to a composition having two or three film-forming agents for applying to cigarette paper, wherein the molecular weight distributions of the film-forming agents are statistically significantly different from each other. The invention further relates to a cigarette paper on which the composition is applied to discrete regions, wherein the regions are characterized by a value for diffusivity, and to a cigarette comprising the cigarette paper, characterized by values for auto-selection. The present invention further relates to a method for producing the cigarette paper and the cigarette.
Claims
1. A method for manufacturing a cigarette paper comprising the following steps: (a) providing a base cigarette paper having a diffusivity of 0.1 to 3 cm/s, measured at room temperature, and/or an air permeability of 10 to 200 CORESTA units; (b) providing a film-forming composition, said film-forming composition comprising a solvent and at least two film forming agents, selected from the group consisting of the film-forming agents A, B and C, of which the molecular weight distributions are statistically significantly different, wherein the content of each film-forming agent in the composition is selected such that the total content of film-forming agents in the composition is 15 to 30% by weight and the viscosity of the composition is from 13 to 22 s measured using a DIN 4 cup at 70 C., and wherein the film-forming agent A has a mean molecular weight of 200,00050,000 g/Mol, the film-forming agent B has a mean molecular weight of 600,000150,000 g/Mol, and the film-forming agent C has a mean molecular weight of 100,00025,000 g/Mol and wherein the content of said two or three film forming agents A, B and C when selected is as follows: film-forming agent A when selected is 5 to 15% by weight, the content of film-forming agent B when selected is 15 to 22% by weight, and the content of film-forming agent C when selected is 2 to 15% by weight of the film-forming composition and wherein the film-forming agents A, B and/or C are selected independently from one another from the group consisting of starch, starch derivatives and starch degradation products; (c) applying the film-forming composition to the cigarette paper by means of intaglio printing or flexographic printing.
2. The method according to claim 1, wherein the content of each film-forming agent in the composition is selected such that the diffusivity in one or more discrete areas of the cigarette paper, in which the composition is applied, is between 0.08 and 0.5 cm/s, measured after the paper has been heated to 230 C. for 30 minutes.
3. The method according to claim 1, wherein the content of each film-forming agent in the composition is selected such that the diffusivity in one or more discrete areas of the cigarette paper, in which the composition is applied, is between 0.2 and 0.4 cm/s, measured after the paper has been heated to 230 C. for 30 minutes.
4. The method according to claim 1, wherein the content of each film-forming agent in the composition is selected such that the diffusivity in one or more discrete areas of the cigarette paper, in which the composition is applied, is between 0.25 and 0.35 cm/s, measured after the paper has been heated to 230 C. for 30 minutes.
5. The method according to claim 1, wherein the film-forming composition comprises two film-forming agents A and B or A and C or B and C.
6. The method according to claim 1, wherein the film-forming composition comprises three film-forming agents A and B and C.
7. The method according to claim 1, wherein the film-forming agent A and/or B is/are a potato starch or a derivate thereof, and the solvent is an aqueous solvent or water.
8. The method according to claim 1, wherein the film-forming agent C is a degraded starch or a derivative thereof, and the solvent is an aqueous solvent or water.
9. The method according to claim 1, wherein the film-forming agent C is a maltodextrin or a derivate thereof, and the solvent is an aqueous solvent or water.
10. The method of claim 1, wherein the film-forming composition further comprises at least one or more additives, selected from the group consisting of carbonates and oxides.
11. The method according to claim 10, wherein the content of additives is up to 15% by weight.
12. The method according to claim 1, wherein in the film-forming composition the total solids content, including the film-forming materials and optionally at least one additive is 15 to 45% by weight.
13. The method of claim 1, wherein the film-forming composition is applied in an amount of 2.5 to 6 g/m.sup.2.
14. The method according to claim 1, wherein the base cigarette paper further comprises one or more burn additives, said one or more burn additives being citrates.
15. The method of claim 14, wherein said citrates are one of a sodium citrate and a tripotassium citrate.
Description
DETAILED DESCRIPTION OF THE INVENTION
(1)
EXAMPLES
(2) The principle on which the invention is based is described by the example of starches and starch derivatives in aqueous solution, but can also be applied to other film-forming agents, including film-forming agents in non-aqueous solutions.
Example 1: Composition of the Printing Solution and Influence on Diffusivity as Well as SE and FB Value
(3) Different film-forming compositions were applied to a cigarette paper by a printing method. The following film-forming substances were used for the printing solution:
(4) Starch A mean molecular weight 200,000 g/Mol
(5) Starch B mean molecular weight 600,000 g/Mol
(6) Starch MD mean molecular weight 100,000 g/Mol
(7) Starches A and B are carboxylated potato starch powder, the starch MD is an enzymatically degraded potato starch (maltodextrin). The solvent was water. The printing solution also contained calcium carbonate, which is normally added to make the printed bands less visible.
(8) The film-forming composition was applied in the form of bands. The printed bands were 6 mm wide and the distance from the middle of one band to the middle of the next band was 27 mm. The bands were arranged at right angles to the direction of movement of the paper web. The printing was achieved with the aid of an intaglio printing system. This is the preferred, technically most common option, but any other desired printing geometry may also be used.
(9) A cigarette paper having following characteristics was used:
(10) Paper A:
(11) TABLE-US-00001 Basis weight 26 g/m.sup.2 Fibers flax pulp Filler calcium carbonate, 29% Air permeability 60 CU (=cm.sup.3/(cm.sup.2 min kPa)) Burn additives 1.0%, 50:50 mixture of sodium- and tripotassium citrate (in % of the entire paper mass)
(12) The cigarettes produced from this paper had the following characteristics:
(13) TABLE-US-00002 Length 84 mm Circumference 24.6 mm Total weight 920 mg Tobacco weight 650 mg Tobacco mixture American Blend
(14) The paper was printed with three different printing solutions according to Table 1. The diffusion constant of the printed areas was then measured and the diffusivity was derived from these values. Afterwards, cigarettes were manufactured from these papers and the cigarettes were tested.
(15) TABLE-US-00003 TABLE 1 Printing solution Diffu- Starch Starch Starch Sum Viscos- Applied sivity MD A B Starch Chalk ity amount D* SE FB Test [%] [%] [%] [%] [%] [s] [g/m.sup.2] [cm/s] [%] [%] 1 5 0 22 27 5 19.0 5.26 0.205 100 60 2 5 22 0 27 5 18.0 5.72 0.405 57 100 3 5 5 17 27 5 19.5 5.50 0.312 95 90
(16) For the printing solution the percentage value denotes the content of the respective materials in percent by weight (% by weight) based on the finished printing solution. For example, the printing solution in test 1 consists of 5% by weight starch MD, 22% by weight of starch B and 5% by weight of calcium carbonate (chalk). The overall content of starch is thus 27% by weight, the total solids content is 32% by weight and the amount of material remaining to 100% by weight is water.
(17) The viscosity is measured using a DIN 4 cup. The time required by a defined volume of the printing solution to flow through an opening in the base of the standardized cup is measured in seconds. The viscosity of the finished printing solution is measured at 70 C.
(18) The applied amount is the additional weight per printed area unit in g/m.sup.2 provided in the bands on the paper after drying.
(19) Diffusivity describes the resistance to a gas exchange caused by a concentration difference in the area of the printed bands. It is closely related to the diffusion constant. The diffusion constant D has the unit m.sup.2/s and describes the flow rate v caused by a concentration gradient grad(c), which is given approximately by grad(c)=(c.sub.1c.sub.2)/d, wherein d is the thickness of the paper and c.sub.1 and c.sub.2 are the concentrations on both sides of the paper. The following relation applies:
(20)
(21) For the technical application, however, it is of specific interest what flow rate through the paper is achieved at a given concentration difference. This should be given by a value characterizing the paper. Thus, the diffusion constant D and the thickness of the paper d are combined to give a value D* according to D*=D/d, which is called diffusivity. It has the unit m/s or cm/s and therefore makes it possible to calculate the flow rate through the band by means of the following equation:
(22)
(23) Different papers can thus be compared on the basis of D*, without additionally having to consider their thickness. Diffusivity, as specified in Table 1, thus corresponds to the diffusion constant divided by the thickness of the paper. It is measured according to a non-standardized method using a CO.sub.2 diffusivity meter from the company SODIM. Diffusivity thus characterizes how easily (high value) or how difficult (low value) oxygen can pass through the cigarette paper to the glowing cone of the cigarette. If the value is already sufficiently low, then the cigarette self-extinguishes. However, during glowing, the cigarette paper is highly thermally exposed in the region of the glowing cone. It has thus been demonstrated that the significance of this measured value can be increased considerably further if the papers are heated beforehand. The paper is therefore heated for 30 minutes to 230 C. in a drying oven, for example in a drying oven ED53 from the company Binder. The changes in the paper and even in the printed bands are irreversible, which is why the paper can initially be cooled down to determine the diffusivity in the region of the bands.
(24) The SE value characterizes the result of the standardized ignition strength test according to ASTM E2187-04. In this test a glowing cigarette is placed on a substrate formed of 10 layers of the filter paper Whatman #2 and it is then checked whether the cigarette self-extinguishes. The percentage value shows how many cigarettes of a sample of 40 self-extinguish.
(25) The FB value characterizes the result of a non-standardized test, in which a glowing cigarette is fixed in a holder in a horizontal position so that air can reach the cigarette on all sides. The cigarette therefore does not lie on a substrate. This test simulates the glowing of the cigarette in an ashtray. The percentage value shows how many cigarettes of a sample of 40 DO NOT self-extinguish.
(26) As can be seen in Table 1, in test 1 in which the printing solution consists primarily of high-molecular starch B, a diffusivity of 0.205 cm/s was achieved. The cigarettes manufactured from the corresponding cigarette paper had an SE value of 100% and an FB value of only 60%. This means that in this example the cigarettes would self-extinguish too often in the ashtray.
(27) In test 2 a mid-molecular starch A was used instead of high-molecular starch B. Accordingly, diffusivity increases from 0.205 cm/s to 0.405 cm/s. Thus, fewer cigarettes self-extinguish and the SE value is only 57%, whereas no cigarettes self-extinguish in the FB test and the FB value is therefore 100%. Such a cigarette self-extinguishes too rarely to comply with the legal requirements.
(28) In test 3 a mixture of starch A and starch B was used and a diffusivity of 0.312 cm/s could be achieved. This value lies between the values obtained in test 1 (0.205 cm/s) and test 2 (0.405 cm/s). The result for the SE value is 95%, which is satisfactory, as is the result for the FB value at 90%.
(29) In this example an applied amount of approximately 5.5 g/m.sup.2 was provided, however good results can also be achieved with a significantly smaller applied amount of down to approximately 2.5 g/m.sup.2.
(30) This example shows that the desired test results for D*, SE and FB can be achieved without significantly changing the solids content of the printing solution, its viscosity or the applied amount. Therefore, an application unit, for example an intaglio printing machine, can be used to apply these differently composed printing solutions without making any adjustments on the application equipment, for example the etching depth of the printing cylinder, the speed of the paper web or the power of the drying unit. This increases the efficiency and the stability of the application process substantially.
Example 2: Influence of the Cigarette Paper
(31) The film-forming materials, the components of the printing solution, the geometry of the bands and the characteristics of the cigarettes produced were as in EXAMPLE 1.
(32) However, a cigarette paper having the following characteristics was used:
(33) Paper B:
(34) TABLE-US-00004 Basis weight 24 g/m.sup.2 Fibers wood pulp Filler calcium carbonate, 29% Air permeability 75 CU (=cm.sup.3/(cm.sup.2 min kPa)) Burn additives 1.0% tripotassium citrate (in % of the entire paper mass)
(35) Paper B thus differs from paper A with regard to all essential characteristics.
(36) TABLE-US-00005 TABLE 2 Printing Solution Diffu- Starch Starch Starch Sum Viscos- Applied sivity MD A B Starch Chalk ity amount D* SE FB Test % [%] [%] [%] [%] [s] [g/m.sup.2] [cm/s] [%] [%] 4 0 5 17 22 5 19.0 4.20 0.250 100 80 5 5 0 17 22 5 17.5 4.45 0.280 97.5 100
(37) In test 5 the mid-molecular starch A of test 4 was replaced by a low-molecular starch MD. Diffusivity increased accordingly from 0.250 cm/s to 0.280 cm/s. The test results show that satisfactory or optimum results could be achieved for the SE and FB values.
(38) This example shows that the adjustment of the test results for D*, SE and FB to different paper characteristics can be achieved without significantly changing the solids content of the printing solution, its viscosity or the applied amount.
(39) It is desirable for the paper manufacturer to recognize, based on the paper characteristic, and without carrying out its own tests, which results are to be expected for SE and FB. This is achieved by the diffusivity D* of the paper, because this variable can be used to predict SE and FB values. Thus, D* is the value which characterizes the paper or, more precisely, the printed areas.
Example 3: Influence of the Air Permeability of the Cigarette Paper
(40) The film-forming materials, the components of the printing solution and the geometry of the bands were as in EXAMPLE 1.
(41) However, cigarette papers having the following characteristics were used:
(42) Paper C
(43) TABLE-US-00006 Basis weight 26 g/m.sup.2 Fibers flax pulp Filler calcium carbonate, 29% Air permeability 60 CU(=cm.sup.3/(cm.sup.2 min kPa)) Burn additives 1.4% tripotassium citrate (in % of the entire paper mass)
Paper D
(44) TABLE-US-00007 Basis weight 26 g/m.sup.2 Fibers flax pulp Filler calcium carbonate, 29% Air permeability 80 CU(=cm.sup.3/(cm.sup.2 min kPa)) Burn additives 1.4% tripotassium citrate (in % of the entire paper mass)
Paper E
(45) TABLE-US-00008 Basis weight 28 g/m.sup.2 Fibers wood pulp Filler calcium carbonate, 25% Air permeability 10 CU(=cm.sup.3/(cm.sup.2 min kPa)) Burn additives 1.0% tripotassium citrate (in % of the entire paper mass)
Paper F
(46) TABLE-US-00009 Basis weight 25 g/m.sup.2 Fibers wood pulp Filler calcium carbonate, 32% Air permeability 200 CU (=cm.sup.3/(cm.sup.2 min kPa)) Burn additives 1.4% tripotassium citrate (in % of the entire paper mass)
(47) TABLE-US-00010 TABLE 3 Printing solution Diffu- Starch Starch Starch Sum Viscos- sivity MD A B Starch Chalk ity D* Test Paper [%] [%] [%] [%] [%] [s] [cm/s] 6 C 5 2 18 25 10 0.210 7 D 5 2 18 25 10 0.232 8 D 2 5 18 25 10 0.208 9 E 18 2 5 25 8 13.5 0.198 10 F 2 0 24 26 5 22.0 0.220
(48) The table shows that when using paper D (80 CU, test 7) instead of paper C (60 CU, test 6) the diffusivity increases from 0.210 cm/s to 0.232 cm/s with the same printing solution. If the proportion of mid-molecular starch A is increased compared to the low-molecular starch MD (test 8), nearly the same diffusivity as in test 6 can be achieved.
(49) As tests 9 and 10 show, satisfactory diffusivity values can also be achieved with a particularly low (10 CU) or a particularly high (200 CU) initial permeability of the cigarette paper.
Example 4: Influence of the Filler of the Cigarette Paper
(50) The film-forming materials, the components of the printing solution and the geometry of the bands were as in EXAMPLE 1.
(51) However, cigarette papers having the following characteristics were used:
(52) Paper G
(53) TABLE-US-00011 Basis weight 26 g/m2 Fibers flax pulp Filler calcium carbonate, 23% Air permeability 100 CU (=cm3/(cm2 min kPa)) Burn additives 2.0% tripotassium citrate (in % of the entire paper mass)
Paper H
(54) TABLE-US-00012 Basis weight 26 g/m2 Fibers flax pulp Filler calcium carbonate, 32% Air permeability 100 CU(=cm3/(cm2 min kPa)) Burn additives 2.0% tripotassium citrate (in % of the entire paper mass)
(55) TABLE-US-00013 TABLE 4 Printing solution Diffu- Starch Starch Sum sivity Starch A B Starch Chalk D* Test Paper MD [%] [%] [%] [%] [%] [cm/s] 11 G 7 2 16 25 10 0.250 12 H 5 2 18 25 10 0.250
(56) When changing from paper G with a filler content of 23% (test 11) to paper H with a filler content of 32% (test 12) it was necessary to shift the proportion of low-molecular starch MD considerably in favor of the high-molecular starch B to maintain the diffusivity of 0.250 cm/s. This is based on the fact that paper H with the higher filler content also has a higher initial diffusivity in the unprinted areas.
Example 5: Influence of the Burn Additives in the Cigarette Paper
(57) The film-forming materials, the components of the printing solution, the geometry of the bands and the characteristics of the manufactured cigarettes were as in EXAMPLE 1. Paper A (test 13) and paper C (tests 14 and 15) were used, which differ only in their content of burn additives (1.0% and 1.4% citrate respectively).
(58) TABLE-US-00014 TABLE 5 Printing solution Diffu- Starch Starch Starch Sum Viscos- Applied sivity MD A B Starch Chalk ity amount D* SE FB Test [%] [%] [%] [%] [%] [s] [g/m.sup.2] [cm/s] [%] [%] 13 0 5 17 22 5 18.5 4.30 0.354 87.5 100 14 0 5 17 22 5 18.5 4.10 0.435 62.5 100 15 0 2 20 22 5 19.0 4.05 0.365 77.5 100
(59) The table shows that when changing from paper A to paper C with the same printing solution, the diffusivity increases from 0.354 cm/s (test 13) to 0.435 cm/s (test 14). At the same time, the SE value decreases from 87.5% to 62.5% and is therefore below the acceptable value of 75%. The reason for this is that the burn additives accelerate the thermal degradation of the paper and therefore increase diffusivity after heating the paper.
(60) By increasing the content of high-molecular starch B from 17% to 20% and reducing the proportion of mid-molecular starch A from 5% to 2%, a diffusivity of 0.365 cm/s can ultimately be achieved in test 15, which leads to an acceptable SE value of 77.5%.
(61) A higher content of burn additives thus has to be compensated for by decreasing diffusivity, which is possible by increasing the content of high-molecular starch.
(62) In this example also, only the proportions of the starches in the printing solution were changed, while the viscosity, solids content and the applied amount remained virtually unchanged.
Example 6: Production of a Film-Forming Composition
(63) To produce the film-forming composition, a double wall or jacketed tank, for example from the company ENCO Energie Componenten GmbH, can be used, which can be heated with steam. The tank should be equipped with a stirrer, for example consisting of a dispersing disc and two propeller stirrers.
(64) Initially, a defined amount of water is filled into the tank and a corresponding amount of calcium carbonate, for example 5 or 11% by weight, is added to the composition with stirring. The calcium carbonate is dispersed for approximately 5 minutes. The suspension is then heated to 50 C. and the corresponding amount of a starch mixture is added. The temperature of the finished composition is then maintained at 90 C. for approximately 20 minutes; the composition is then ready for use.
(65) As an alternative to calcium carbonate, aluminum hydroxide can also be used and serves the same purpose, namely an improvement of the optical characteristics of the bands, in particular an increase in opacity.
Example 7: Adjustment of a Film-Forming Composition
(66) Depending on the paper characteristics, recommended starting values for the production of a printing solution to obtain a diffusivity of approximately 0.3 cm/s are those given in Table 6. These values must then be adjusted to the filler content and the content of burn additives of the paper as well as the content of calcium carbonate in the printing solution. The values in the table apply to a filler content of 25% and 1% tripotassium citrate in the paper and 5% calcium carbonate in the printing solution.
(67) TABLE-US-00015 TABLE 6 Air Starch permeability MD Starch A Starch B Pulp [CU] [%] [%] [%] Wood 40 5 0 17 60 2 3 17 80 0 5 17 Flax 60 7 2 16 80 4 4 17 100 0 7 18
Example 8: Thermogravimetric Curves
(68)
(69) It can be seen in