Composition for coating a paper wrapper for smoking articles

Abstract

The present invention relates to a composition for coating paper wrapper for smoking articles, which comprises a combination of gum arabic, preferably between 40% and 95% by weight with respect to the total dry material weight of the composition, and a filler that comprises calcium carbonate, preferably in an amount of at least 5% by weight with respect to the dry material weight of the composition, alone or in combination with other substances such as, for example, kaolin, calcium sulphate, titanium dioxide and mixtures thereof, and to the use thereof for producing a paper wrapper for smoking articles.

Claims

1. A composition for coating paper wrappers for smoking articles, consisting of water, between 40% and 95% by weight of gum arabic with respect to the total dry material weight of the composition, and between 5 and 60% by weight of calcium carbonate with respect to the total dry material weight of the composition, wherein the composition has a viscosity of between 80 and 600 cps, measured with a Brookfield RVT viscometer at room temperature, and wherein a smoking article comprising a paper wrapper coated with the composition is self-extinguishing and has an SE value equal or higher than 75% and a FASE value equal or lower than 15%.

2. A method of coating a paper wrapper for a smoking article comprising applying a composition as a total or partial coating of a paper wrapper that wraps the tobacco rod of the smoking article, wherein the composition comprises gum arabic and a filler, wherein the filler comprises calcium carbonate alone or in combination with substances selected from the group consisting of kaolin, calcium sulphate, citrate, titanium dioxide and mixtures thereof, wherein the composition comprises: between 40% and 95% by weight of gum arabic with respect to the total dry material weight of the composition, and between 5% and 60% of calcium carbonate with respect to the total dry material weight of the composition, wherein the composition has a viscosity of between 80 and 600 cps, measured with a Brookfield RVT viscometer at room temperature, wherein the composition is applied by printing by means of a technique selected from the group consisting of flexography and rotogravure, and wherein the composition provides a self-extinguishing smoking article having an SE value equal or higher than 75% and a FASE value equal or lower than 15%.

3. The method of claim 2, wherein the composition is applied on a paper wrapper that wraps the tobacco rod of the smoking article as partial coating, in the form of bands parallel to each other and arranged perpendicularly to the longitudinal axis of the smoking article.

4. The method of claim 2, wherein the composition is applied on a wrapper that wraps the tobacco rod of the smoking article paper as partial coating, in the form of bands parallel to each other and arranged at an angle of between 0.5° and 5°, approximately with respect to the perpendicular of the longitudinal axis of the smoking article.

5. The method of claim 4, wherein the bands parallel to each other have a width of between 4 and 10 mm.

6. The method of claim 4, wherein the bands parallel to each other have a width of between 6 and 8 mm.

7. The method of claim 4, wherein the bands parallel to each other are separated by a distance of between 10 and 30 mm.

8. The method of claim 4, wherein the bands parallel to each other are separated by a distance of between 15 and 25 mm.

9. The method of claim 2, wherein the composition is applied by printing the paper wrapper that wraps the tobacco rod of a smoking article in amounts comprised between 0.5 and 10 grams of dry material per square meter of paper, measured in the printed area.

10. The method of claim 2, wherein the composition is applied by printing the paper wrapper that wraps the tobacco rod of the smoking article in amount comprised between 0.9 and 8 grams of dry material per square meter of paper, measured in the printed area.

11. The method of claim 2, wherein the composition comprises between 45% and 90% by weight of gum arabic with respect to the total dry material weight of the composition.

12. The method of claim 2, wherein the composition consists of water, between 40% and 95% by weight of gum arabic with respect to the total dry material weight of the composition, and between 5 and 60% by weight of calcium carbonate with respect to the total dry material weight of the composition, wherein the composition provides a self-extinguishing smoking article having an SE value equal or higher than 75% and a FASE value equal or lower than 15%, and wherein the composition has a viscosity of between 80 and 600 cps, measured with a Brookfield RVT viscometer at room temperature.

13. The method of claim 2, wherein the composition consists of water, between 40% and 95% by weight of gum arabic with respect to the total dry material weight of the composition, and a filler consisting of calcium carbonate and substances selected from the group consisting of kaolin, calcium sulphate, citrate, titanium dioxide and mixtures thereof, wherein the calcium carbonate is present in an amount of between 5% and 60% by weight with respect to the total dry material weight of the composition, wherein the composition provides a self-extinguishing smoking article having an SE value equal or higher than 75% and a FASE value equal or lower than 15%, and wherein the composition has a viscosity of between 80 and 600 cps, measured with a Brookfield RVT viscometer at room temperature.

14. A coated paper wrapper for obtaining a self-extinguishing smoking article, wherein such coated paper wrapper comprises a composition as a total or partial coating, wherein the composition comprises gum arabic and a filler, wherein the filler comprises calcium carbonate alone or in combination with substances selected from the group consisting of kaolin, calcium sulphate, citrate, titanium dioxide and mixtures thereof, wherein the composition comprises: between 40% and 95% by weight of gum arabic with respect to the total dry material weight of the composition, and between 5% and 60% of calcium carbonate with respect to the total dry material weight of the composition, wherein the composition has a viscosity of between 80 and 600 cps, measured with a Brookfield RVT viscometer at room temperature, wherein the coated paper wrapper wraps a tobacco rod of a smoking article, and wherein the coated paper wrapper provides a self-extinguishing smoking article having an SE value equal or higher than 75% and a FASE value equal or lower than 15%.

15. The coated paper wrapper according to claim 14, wherein such paper wrapper comprises, at least, areas coated with an ink composed by: a percentage of dry material of between 25 and 40% by weight with respect to the total composition, between 40% and 95% by weight of gum arabic with respect to the dry material weight, between 5 and 60% by weight, of calcium carbonate with respect to the dry material weight, 3.5% by weight, of a combustion agent selected from the group consisting of trisodium citrate, tripotassium citrate, and mixtures thereof, the coated paper wrapper having an initial air permeability of between 10 CU and 150 CU.

16. A self-extinguishing smoking article which comprises the coated paper wrapper defined in claim 14, wherein the coated paper wrapper wraps a tobacco rod of the smoking article, and wherein the coated paper wrapper provides a self-extinguishing smoking article with an SE value equal or higher than 75% and a FASE value equal or lower than 15%.

17. A composition for coating paper wrappers for smoking articles consisting of water, between 40% and 95% by weight of gum arabic with respect to the total dry material weight of the composition, and a filler consisting of calcium carbonate and substances selected from the group consisting of kaolin, calcium sulphate, citrate, titanium dioxide and mixtures thereof, wherein the calcium carbonate is present in an amount of between 5% and 60% by weight with respect to the total dry material weight of the composition, wherein the composition has a viscosity of between 80 and 600 cps, measured with a Brookfield RVT viscometer at room temperature, and wherein a smoking article comprising a paper wrapper coated with the composition is self-extinguishing and has an SE value equal or higher than 75% and a FASE value equal or lower than 15%.

18. The composition according to claim 17, wherein the filler comprises calcium carbonate and a citrate selected from the group consisting of trisodium citrate, tripotassium citrate, and mixtures thereof.

19. A coated paper wrapper for obtaining a self-extinguishing smoking article, wherein such coated paper wrapper comprises the composition defined in claim 1 as a total or partial coating.

20. A coated paper wrapper for obtaining a self-extinguishing smoking article, wherein such coated paper wrapper comprises the composition defined in claim 17 as a total or partial coating.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the results obtained of percentage of extinguished cigarettes, measured according to ASTM E2187 (SE) and according to the parameter of free combustion extinguishment (FASE), against the diffusivity values, for cigarettes with a filler exclusively of calcium carbonate.

(2) FIG. 2 shows the results obtained of percentage of extinguished cigarettes, measured according to ASTM E2187 (SE) and according to the parameter of free combustion extinguishment (FASE), against the diffusivity values, for cigarettes with a filler exclusively of aluminium hydroxide.

EXAMPLES OF EMBODIMENT

(3) Preparation of a Coating Composition

(4) The preparation of a composition according to the invention is described in the patent application WO2003/15543.

(5) Such composition is prepared by dissolving a predetermined amount of gum arabic or acacia gum in water in concentrations that vary between 40 and 95% by weight with respect to the total weight of dry material of the composition, preferably between 45 and 90% by weight, more preferably between 50 and 80% by weight, and even more preferably between 60 and 68% by weight, the rest of solids being calcium carbonate at least. Water is added until completing 100% by weight.

(6) The preparation of the coating liquid ink, or composition, is made by mixing the appropriate amounts of a solution of gum arabic in water at 39% and calcium carbonate in the suitable system to achieve a good dispersion of the calcium carbonate (normally, said system are stirrers with an important shear component such as for example, a Silverstone stirrer), adding at the end the required amount of water to adjust the suitable concentration of dry material.

(7) This concentration of dry material depends basically on two factors: the printing parameters, which in flexography is mainly the volume of anilox roller the diffusivity and/or the air permeability of the paper wrapper for smoking articles to be printed. The diffusivity and/or the air permeability of the paper wrapper for smoking articles are not parameters that strictly measure the same, although they are related for a specific sample of paper wrapper for smoking articles.

(8) Example of application of the coating composition and analysis of the influence of the type of filler.

(9) To determine the working limits with our technology, we have started from an ink consisting of 67% by weight of dry material of gum arabic, and 33% by weight with respect to dry material, of filler at several levels of content in solids, this filler being aluminium hydroxide with a particle size of 1.2 microns in one case and calcium carbonate precipitated with a particle size of less than 1 micron in the other. With this composition there have been printed bands with different weights on a paper wrapper for smoking articles manufactured with wood fibres and with an air permeability of 50 CU.

(10) Specific Application Mode of the Composition to the Wrap

(11) The layer of ink or coating composition was printed with a central drum flexographic machine, using a 30 cc/m.sup.2 anilox and a 2.54 mm etching plate.

(12) The diffusivity of the bands printed has been analyzed and cigarettes have been manufactured using tobacco of a typical “American blend”. The cigarettes have been analyzed according to the ASTM E2187 method for determining their extinguishment on a filter paper support (SE). Likewise their free combustion extinguishment (FASE) has been determined.

(13) FIGS. 1 and 2 show the results of percentage of extinguished cigarettes measured according to the self-extinguishment (SE) parameter and according to the free combustion extinguishment (FASE) parameter, against the diffusivity values, for cigarettes with a filler exclusively of calcium carbonate (FIG. 1) and for cigarettes with a filler exclusively of aluminium hydroxide (FIG. 2).

(14) Taking into account that the objectives are to obtain a minimum of 75% of cigarettes extinguished on support (% SE) and a FASE value as low as possible, this study shows that the values of % FASE for this value of 75% SE are substantially lower using calcium carbonate than using aluminium hydroxide (approximately, 50% FASE with aluminium hydroxide and 15% with calcium carbonate). In addition, the range of diffusivity values to obtain at least 75% of SE is greater for the case of calcium carbonate (0 to 0.293 cm/sec) than for the case of aluminium hydroxide (0 to 0.172 cm/sec).

(15) Example of a Cigarette Wrap According to the Invention

(16) Although any paper wrapper for smoking articles, as is the case of those having a permeability to air comprised between 15 and 150 CU, is useful for the object of the present invention, for demonstration purposes in the following table are indicated the characteristics of the paper used in the following tests:

(17) TABLE-US-00001 TABLE 1 Characteristics of the paper wrapper for smoking articles: TYPE OF PAPER VERGE EXTRA 824 N-50_CO WEIGHT g/m.sup.2 25.5 ASHES, % 17.0 POROSITY, CU 49.1 STREGTH, g/15 mm 1400 ELONGATION, % 1.4 COMBUSTION ADDITIVES * 0.70 * percentage of citric acid monohydrate

(18) What is defined as ashes is a measure of the content of mineral filler of the paper, which in the case of the paper wrapper for smoking articles, is normally calcium carbonate. The experimental factor by which this value has to be multiplied to obtain the percentage of calcium carbonate is 1.695.

(19) The data of composition of the ink, layer weight applied, together with the diffusivity measured in the band and the SE and FASE values of the cigarettes manufactured with these papers are shown in tables 2 and 3, in the following.

(20) TABLE-US-00002 TABLE 2 Composition with aluminium hydroxide: Layer Ink composition Weight, Diffusivity, (% by weight) g/m.sup.2 cm/sec % SE % FASE 25% Gum arabic 4.4 0.06 100 100 12.4% aluminium hydroxide 20% Gum arabic 3.4 0.122 100 85 9.9% aluminium hydroxide 16% Gum arabic 2.5 0.248 35 0 7.9% aluminium hydroxide 12.1% Gum 1.7 0.642 0 0 arabic 5.9% aluminium hydroxide

(21) TABLE-US-00003 TABLE 3 Composition with calcium carbonate: Layer % by weight, in Weight, Diffusivity, the composition g/m.sup.2 cm/sec % SE % FASE 25% Gum arabic 3.9 0.129 100 100 12.4% calcium carbonate 20% Gum arabic 3.2 0.144 100 100 9.9% calcium carbonate 16% Gum arabic 2.5 0.293 75 15 7.9% calcium carbonate 12.1% Gum 1.7 0.476 10 0 arabic 5.9% calcium carbonate

(22) In all the cases, the percentages of gum arabic and calcium carbonate on dry material are 67% and 33% respectively. The percentage of dry material of the ink used in the printing varies.

(23) FIGS. 1 and 2 show the relationship between diffusivity of the band and the SE and FASE percentages for each type of filler.

(24) It is very difficult to achieve predetermined SE values, so inks with various contents of dry material are prepared keeping the relationship between gum arabic and filler, and it is interpolated.