Cigarette paper with high short-fiber fraction

Abstract

A wrapping paper for smoking articles has a basis weight of at least 10 g/m.sup.2 and at most 70 g/m.sup.2 and comprises a mixture of cellulosic pulp fibers comprising at least 90% of short-fiber cellulosic pulp fibers, based on the mass of the cellulosic pulp fibers in the cellulosic pulp mixture, or comprising at least 95% of short-fiber cellulosic pulp fibers, based on the number of cellulosic pulp fibers, with at least 10% of the short-fiber cellulosic pulp fibers being ground, based on the mass of the number of cellulosic pulp fibers of the cellulosic pulp fiber mixture, and with the wrapping paper having over more than 50% of its area, preferably at least 55% of its area and especially preferably at least 60% of its area, an air permeability of at least 30 cm.sup.3/(cm.sup.2,min-kPa), and where the wrapping paper comprises at least one burning salt.

Claims

1. Wrapping paper for smoking articles with a basis weight of at least 10 g/m.sup.2 and at most 70 g/m.sup.2, comprising: a mixture of pulp fibers, wherein the mixture of pulp fibers is formed by at least 90% of short-fiber pulp fibers with respect to the mass of the pulp fibers in the pulp mixture, or by at least 95% short-fiber pulp fibers with respect to the number of pulp fibers, wherein said short-fiber pulp is at least primarily sourced from deciduous trees, wherein the fibers of the pulp mixture have a mean length of at least 0.1 mm and of at most 1.5 mm, and wherein at least 10% of the short-fiber pulp fibers, with respect to the mass or number of the pulp fibers of the pulp mixture, are refined, wherein more than 50% of the surface area of the wrapping paper has an air permeability of at least 30 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), and wherein the wrapping paper contains at least one burn additive, wherein said wrapping paper has a tensile strength in the machine direction in accordance with ISO 1924-2:2008 of at least 10 N/15 mm and at most 25 N/15 mm, an elongation at break in the machine direction in accordance with ISO 1924-2:2008 of at least 0.9% and at most 3.0%, and a diffusion capacity in untreated areas that is at least 0.1 cm/s and at most 4.0 cm/s.

2. Wrapping paper according to claim 1, wherein the wrapping paper has coated areas which make up less than 50% of the surface area of the wrapping paper.

3. Wrapping paper according to claim 1, wherein the fraction of the short-fiber pulp with respect to the mass of the pulp fibers in the pulp mixture is at least 95%.

4. Wrapping paper according to claim 1, wherein the fraction of refined short-fiber pulp fibers, with respect to the mass of the entire pulp fibers, is at least 30% and at most 100%, or with respect to the total number of pulp fibers, is at least 35% and at most 100%.

5. Wrapping paper according to claim 1, wherein the degree of refining of the refined short-fiber pulp in accordance with ISO 5267-1:1999 is at least 20 SR and at most 80 SR.

6. Wrapping paper according to claim 1, wherein the degree of refining of the pulp mixture in the wrapping paper is at least 30 SR and at most 70 SR.

7. Wrapping paper according to claim 1, wherein the short-fiber pulp is at least primarily sourced from one or more of the following trees: birch, beech, eucalyptus, poplar or aspen.

8. Wrapping paper according to claim 1, with a basis weight of at least 25 g/m.sup.2 and at most 40 g/m.sup.2.

9. Wrapping paper according to claim 1, further comprising one or more filler materials, wherein at least a fraction of the one or more filler materials is selected from a group which consists of calcium carbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate and aluminum hydroxide.

10. Wrapping paper according to claim 1, wherein the wrapping paper has a filler content of at most 45% by weight and at least 10% by weight, each referred to the weight of the wrapping paper.

11. Wrapping paper according to claim 1, further comprising: at least a burn additive selected from the group consisting of citrates, malates, tartrates, acetates, succinates, fumarates, gluconates, glycolates, lactates, oxalates, salicylates, -hydroxy caprylates, phosphates and hydrogen carbonates.

12. Wrapping paper according to claim 11, wherein the burn additive content is at least 0.5% by weight, and at most 7.0% by weight.

13. Wrapping paper according to claim 1, with an air permeability in untreated areas that is at least 50 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), and at most 5000 cm.sup.3/(cm.sup.2.Math.min.Math.kPa).

14. Wrapping paper according to claim 1, which further has areas of reduced diffusion capacity which serve to self-extinguish a smoking article manufactured therefrom.

15. Wrapping paper according to claim 1, which further is artificially perforated at least in sections.

16. Smoking article comprising a rod of tobacco or a different material, which forms smoke or an aerosol upon combustion or heating, wherein this rod is wrapped with a wrapping paper according to claim 1.

17. Smoking article according to claim 16, which comprises a filter which is connected with the wrapped rod via a tipping paper.

18. Wrapping paper according to claim 11, wherein said burn additive is selected from the group consisting of trisodium citrate and tripotassium citrate.

19. Wrapping paper according to claim 11, wherein the burn additive content is at least 0.7% by weight and at most 3.0% by weight.

20. Wrapping paper according to claim 13, with an air permeability in untreated areas that is at least 70 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 500 cm.sup.3/(cm.sup.2.Math.min.Math.kPa).

Description

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) The following embodiments are intended to demonstrate the effect according to the invention.

(2) Birch pulp and eucalyptus pulp were selected as a short-fiber pulp for the wrapping paper according to the invention. Calcium carbonate was used as a filler material.

(3) TABLE-US-00001 TABLE 1 Degree of Pulp Refining Birch Eucalyptus Filler Birch refined unrefined unrefined Chalk refined Mixture No. % % % % SR SR 1 40 60 0 0 30 22 2 40 60 0 0 40 25 3 20 80 0 0 40 21 4 80 0 20 36.5 36 33 5 80 0 20 39.3 52 46 6 80 0 20 43.0 71 60 7 80 0 20 0 36 33 8 80 0 20 0 52 46 9 80 0 20 0 71 60 10 80 0 20 30.5 79 57 11 80 0 20 0 79 57

(4) Table 1 shows 11 different fiber/filler compositions, from which exemplary wrapping papers were manufactured. The fiber/filler composition is characterized by the fractions of refined birch pulp (Birch refined column), unrefined birch pulp (Birch unrefined column), unrefined eucalyptus pulp (Eucalyptus unrefined column) and filler materials (Filler column). The percentages for the refined and unrefined birch and eucalyptus pulp refer to the mass of the entire pulp mixture. The data for filler in percent, however, is with respect to the mass of the finished wrapping paper. In the columns headed Degree of Refining, the degree of refining is given in accordance with ISO 5267-1:1999 in Schopper-Riegler ( SR). Therein the column Birch refined contains the values for the refined birch pulp only and the column Mixture contains the values for the entire pulp mixture without filler.

(5) As can be seen in Table 1, for the compositions 1-3, mixtures of refined and unrefined birch pulp were used, while in the compositions 4-11, mixtures of refined birch pulp and unrefined eucalyptus pulp were used. The compositions 4-6 and 10 additionally contained precipitated calcium carbonate (Chalk) as a filler material. The refined birch pulp was refined to degrees of refining between 30 SR and 79 SR. This already shows an essential advantage of the invention because, to refine the birch pulp, only about half the refining energy required for normal long-fiber pulp with respect to the mass was needed. This leads to substantial savings in refining energy.

(6) In respect of the design of a wrapping paper, the compositions in Table 1 are the extreme points regarding the degree of refining, the filler content and the fractions of refined and unrefined short-fiber pulp, so that the skilled person will primarily select values between these extreme points when designing a wrapping paper for smoking articles according to the invention.

(7) The fiber length distribution of the refined birch pulp was measured several times with a Fiber Tester Code 912, Type 987666, from the company Lorentzen & Wettre, in accordance with the instructions of the manufacturer of the measuring instrument, and a mean fiber length between 0.8 and 1.0 mm was obtained.

(8) The refined birch pulp was mixed in an aqueous suspension with the unrefined birch pulp or the unrefined eucalyptus pulp according to the mixture ratios in Table 1. The filler was added to the suspension in the appropriate quantity and sheets were formed from the suspension on a laboratory sheet former and dried. In total, 14 wrapping papers were thus produced, whose data are given in Table 2.

(9) Table 2 shows 14 exemplary embodiments according to the invention A-N (column Example), wherein for each embodiment, one of the fiber/filler suspensions of Table 1 was used. Column 2 of Table 2 shows the Composition No.. The numbers provided therein correspond to the number in the column No. of Table 1.

(10) After a conditioning step for the sheets in accordance with ISO 187 at 23 C. and 50% relative humidity, different measurements were carried out on the sheets, the results of which are provided in Table 2.

(11) TABLE-US-00002 TABLE 2 Elonga- Tensile tion Air Compo- Basis Strength at Permeability Diffusion sition Weight N/15 Break cm.sup.3/(cm.sup.2 .Math. Capacity Example No. g/m.sup.2 mm % min .Math. kPa) cm/s A 1 25 10 7200 3.7 B 2 25 12 4900 3.2 C 3 25 9 7500 3.8 D 1 60 148 0.6 E 2 60 90 0.5 F 3 60 175 0.7 G 4 35 5 0.9 580 3.6 H 5 34 6 1.1 308 3.0 I 6 37 8 1.4 147 2.4 J 7 23 20 2.5 1240 2.3 K 8 23 21 2.5 272 1.1 L 9 23 24 2.4 75 0.4 M 10 37 10 1.5 203 2.0 N 11 25 25 2.8 142 0.6

(12) The basis weight was measured in accordance with ISO 536:2012; the results are provided in the column headed Basis Weight. The tensile strength and elongation at break were measured in accordance with ISO 1924-2:2008 and are provided in the columns Tensile Strength and Elongation at Break. The air permeability was measured in accordance with ISO 2965:2009 and is provided in the column Air Permeability. Finally, the diffusion capacity was also measured in accordance with CORESTA Recommended Method No. 77 (April 2014) and the values are provided in the column Diffusion Capacity.

(13) From examples A-C it can be seen that even at a basis weight of 25 g/m.sup.2, a sufficient tensile strength of at least 9 N/15 mm can be achieved so that the wrapping paper can be processed automatically into a smoking article without problems. The air permeabilities of examples A-C of 4900 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) to 7500 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) are very high for common wrapping papers for smoking articles; by increasing the basis weight, the refining energy or the fraction of refined birch pulp, but also by selecting a different short-fiber pulp, the air permeability can be reduced if needed. The diffusion capacities of the wrapping papers from examples A-C are also high, which can reduce the carbon monoxide content in the smoke of a smoking article manufactured therefrom.

(14) Examples D-F use the same fiber/filler suspensions 1-3 as the examples A-C, but at a considerably higher basis weight of 60 g/m.sup.2. Thus, the air permeability, with values of 90 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) to 175 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) is also substantially lower than in the examples A-C. The diffusion capacities of the wrapping papers of the examples D-F of 0.5 cm/s to 0.7 cm/s are within the usual range for wrapping papers for smoking articles. The tensile strength was not measured because the composition of the wrapping papers of the examples D-F is the same as for the examples A-C and because of the higher basis weight, a substantial increase in tensile strength would be expected, so that the values will in any case be substantially above 12 N/15 mm, which is the highest value for examples A-C.

(15) The wrapping papers of examples G-N contained refined birch pulp and unrefined eucalyptus pulp and examples G, H, I and M also contained filler material. The basis weights are within a normal range for conventional wrapping papers for smoking articles of 23 g/m.sup.2 to 37 g/m.sup.2. The examples G and H, with a tensile strength of 5 N/15 mm and 6 N/15 mm respectively, are just within an acceptable range. From these examples, it can be seen that by refining the birch pulp a little and using a high fraction of filler material of 36.5% (example G) and 39.3% (example H), the tensile strength of the wrapping paper is reduced. For example I, however, the filler content is even higher at 43%, but the birch pulp is also refined to a higher degree of refining of 71 SR. Thus, a tensile strength of 8 N/15 mm is achieved, which may be sufficient for, automatic processing of the wrapping paper, but is in any case sufficient for a wrapping paper for manually produced smoking articles.

(16) For examples G-N the elongation at break was also measured. Values from 0.9% to 2.8% were found, which is in any case sufficient for automatic processing of the wrapping paper.

(17) The air permeability of the wrapping paper of examples G-N is in the range from 75 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) to 1240 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), and fully covers the normal range of wrapping papers for smoking articles. The same applies to the diffusion capacities of examples G-N, which are between 0.4 cm/s and 3.6 cm/s.

(18) The wrapping papers described can be used to manufacture a smoking article, for example by using the wrapping papers to wrap a tobacco rod or a different material which releases an aerosol upon heating or combustion. Because all essential properties of the wrapping paper of the examples A-N lie in a typical range for a wrapping paper for smoking articles, the manufacturing processes for manufacturing smoking articles do not differ from those known from the prior art. For this reason, the processes for manufacturing corresponding smoking articles have not been described in the present description.

(19) Overall, it can be seen from the exemplary embodiments A-N that, contrary to expectations, wrapping papers for smoking articles with the typical properties of such wrapping papers can be manufactured by primarily or exclusively using short-fiber pulp. In contrast to the prior art, this is possible with substantial savings in costs for energy and raw materials.