Cigarette paper comprising flaky filler

Abstract

A cigarette paper contains pulp fibers and filler particles, whereby at least 20% of the filler particles, by mass or by particle number, have a flaked shape. The flaked filler particles have a length l, a width b and a thickness d, which correspond to the respective maximum extension in three mutually orthogonal spatial directions, whereby the length l as well as the width b are at least twice as large as the thickness d. The mass-specific median value d.sub.50 of the particle size distribution measured according to ISO 13317-3 is between 0.2 μm and 4.0 μm, and the flaked particles are formed by calcium carbonate.

Claims

1. Cigarette paper, which contains pulp fibers and filler particles, whereby at least 20% of the filler particles, by mass or by particle number, have a flaked shape, wherein the flaked filler particles have a length l, a width b and a thickness d, which correspond to the respective maximum extension in three mutually orthogonal spatial directions, whereby the length l as well as the width b are at least twice as large as the thickness d, wherein the mass-specific median value d.sub.50 of the particle size distribution measured according to ISO 13317-3 is between 0.2 μm and 4.0 μm, and wherein the flaked particles are formed by calcium carbonate; and wherein the cigarette paper has an air permeability of x CORESTA Units and a diffusion capacity D.sub.x.sup.* for CO.sub.2, and whereby D.sub.x.sup.*.Math.√{square root over (50)}/√{square root over (x)}≧1.80 cm/s holds.

2. Cigarette paper according to claim 1, wherein D.sub.x.sup.*.Math.√{square root over (50)}/√{square root over (x)}≧1.85 cm/s holds.

3. Cigarette paper according to claim 1, wherein D.sub.x.sup.*.Math.√{square root over (50)}/√{square root over (x)}≧1.90 cm/s holds.

4. Cigarette paper according to claim 1, whereby 20≦×≦120 holds.

5. Cigarette paper according to claim 1, wherein preferably 30≦×≦100 holds.

6. Cigarette paper according to claim 1, wherein the mass-specific median value d.sub.50 of the particle size distribution measured according to ISO 13317-3 is between 0.5 μm and 3.0 μm.

7. Cigarette paper according to claim 1, whereby the calcium carbonate comprises a calcite, a vaterite or a mixture thereof.

8. Cigarette paper according to claim 7, whereby the mixture consists of 50% by weight to 70% by weight calcite and 30% by weight to 50% by weight vaterite.

9. Cigarette paper according to claim 1, wherein the entire filler content of the paper is between 10% by weight and 45% by weight.

10. Cigarette paper according to claim 1, wherein the entire filler content of the paper is between 20% by weight and 35% by weight.

11. Cigarette paper according to claim 1, wherein the basis weight is between 10 g/m.sup.2 and 60 g/m.sup.22.

12. Cigarette paper according to claim 1, wherein the basis weight is between 20 g/m.sup.2 and 35 g/m.sup.2.

13. Cigarette paper according to claim 1, wherein the paper is treated in areas with burn-retardant substances, which are suitable for providing a cigarette manufactured from the paper with self-extinguishing properties.

14. Cigarette paper of claim 1, wherein at least 40% of the filler particles, by mass or by particle number, have a flaked shape.

15. Cigarette paper of claim 1, wherein at least 55% of the filler particles, by mass or by particle number, have a flaked shape.

16. Cigarette paper of claim 1, wherein at least 70% of the filler particles, by mass or by particle number, have a flaked shape.

17. A cigarette, comprising a tobacco rod and a cigarette paper wrapping the tobacco rod, whereby the cigarette paper is a cigarette paper, which contains pulp fibers and filler particles , whereby at least 20% of the filler particles, by mass or by particle number, have a flaked shape, wherein the flaked filler particles have a length l, a width b and a thickness d, which correspond to the respective maximum extension in three mutually orthogonal spatial directions, whereby the length l as well as the width b are at least twice as large as the thickness d, wherein the mass-specific median value d.sub.50 of the particle size distribution measured according to ISO 13317-3 is between 0.2 μm and 4.0 μm, and wherein the flaked particles are formed by calcium carbonate; and wherein the cigarette paper has an air permeability of x CORESTA Units and a diffusion capacity D.sub.x.sup.* for CO.sub.2, and whereby D.sub.x.sup.*.Math.√{square root over (50)}/√{square root over (x)}≧1.80 cm/s holds.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic drawing of a flaked filler particle, where the length l, the width b and the thickness d are shown.

DETAILED DESCRIPTION

EXAMPLE 1

(2) The starting point for Example 1 is a cigarette paper not according to the invention comprising wood pulp fibers and 25.5% by weight of a conventional, non-flaked, precipitated calcium carbonate, which serves as an example for comparison. Further substances, however, for example, burn additives, can be included. The cigarette paper had a basis weight of 28.2 g/m.sup.2 and an air permeability of 46.9 CU. The CO.sub.2 diffusion capacity was measured with a CO.sub.2 Diffusivity Meter from the company Sodim after conditioning the paper according to ISO 187 and was found to be D.sub.46.9.sup.*=1.59 cm/s.

(3) A further, identical cigarette paper was produced, for which a calcium carbonate with flaked particles was used instead of the conventional calcium carbonate. An X-ray structural analysis showed that it was a mixture of about 60% by weight calcite and about 40% by weight vaterite. The mean particle diameter was about 1.1 μm. A method to produce such flaked calcium carbonate is described in EP 1 151 966 B1.

(4) It can be seen that by exchanging the calcium carbonate, an increase in the diffusion capacity from 1.59 cm/s to 1.81 cm/s can be achieved with practically identical paper properties, that is by 13.8%. It has to be considered here that the air permeability of the paper with the flaked chalk according to the invention is slightly lower, at 41.7 CU, than that of the paper of the comparative example, at 46.9 CU. This small difference in air permeability can be easily compensated for, for example, by changing the refining intensity of the pulp and it is to be expected that with identical air permeability, the increase in diffusion capacity would be even greater. If the diffusion capacity is normalized to an air permeability of 50 CU in the manner described above, a normalized diffusion capacity of D.sub.50.sup.*=1.59 cm/s.Math.√{square root over (50)}/√{square root over (46.9)}=1.64 cm/s results for the comparative example, while for the cigarette paper of example 1 with the flaked chalk according to the invention, a normalized diffusion capacity D.sub.50.sup.* of 1.81 cm/s.Math.√{square root over (50)}/√{square root over (41.7)}=1.98 cm/s is obtained.

EXAMPLE 2

(5) A cigarette paper not according to the invention comprising 30.2% by weight of a conventional, non-flaked, precipitated calcium carbonate was produced as comparative example. The paper had a basis weight of 28.8 g/m.sup.2, an air permeability of 60.6 CU and a diffusion capacity of 1.84 cm/s, again measured with the CO.sub.2 Diffusivity Meter from the company Sodim after conditioning the paper according to ISO 187. This corresponds to a value normalized to 50 CU of D.sub.50.sup.*=1.84 cm/s.Math.√{square root over (50)}/√{square root over (60.6)}=1.67 cm/s, which is thus similar to that of the comparative example of Example 1.

(6) This cigarette paper was modified by using a mixture of calcite and vaterite with a flaked structure instead of the conventional calcium carbonate. The modified cigarette paper had a filler content of 31.0% by weight, a basis weight of 29.1 g/m.sup.2 and an air permeability of 59.5 CU. The diffusion capacity was 2.17 cm/s. An increase in the diffusion capacity from 1.84 cm/s to 2.17 cm/s, i.e.17.9%, could be achieved thereby for otherwise almost identical paper properties. Such a high diffusion capacity as obtained with the paper according to the invention according to example 2 would be expected for conventional cigarette papers at an air permeability of at least about 85 CU. The diffusion capacity D.sub.50.sup.* normalized to an air permeability of 50 CU is thereby 2.17 cm/s.Math.√{square root over (50)}/√{square root over (59.5)}=1.99 cm/s and is therefore similar to Example 1.

(7) Consequently, the cigarette papers according to the invention allow a substantially improved diffusion of carbon monoxide out of the tobacco rod of a cigarette manufactured from this paper, without having to change the air permeability of the cigarette paper.

(8) Although various exemplary embodiments of the invention have been disclosed, it should be apparent to those skilled in the art that various changes and modifications can be made which will achieve some of the advantages of the invention without departing from the true scope of the invention.