Smoking articles with reduced ignition proclivity characteristics
View Patent ↗A process for reducing the permeability of a paper wrapper used in the construction of a smoking article is disclosed. The paper wrapper is treated with a film-forming composition that forms treated discrete areas on the wrapper. The treated discrete areas have a permeability within a predetermined range sufficient to reduce the ignition proclivity properties of a smoking article made with the wrapper. In accordance with the present invention, the film-forming composition contains a film-forming material. The film-forming material has a relatively low viscosity. In this manner, the film-forming composition can have a relatively high solids content and still be applied to the wrapper using conventional techniques, such as by using a gravure printer.
1. A process for producing a paper wrapper having reduced ignition proclivity characteristics when incorporated into a smoking article comprising:
applying a film-forming composition to a paper wrapper at particular locations, the paper wrapper comprising a paper web containing a filler, the paper wrapper having a basis weight of from about 18 gsm to about 60 gsm, said film-forming composition forming treated discrete areas on said wrapper, the treated areas being separated by untreated areas, the treated discrete areas having a BMI of less than about 5 cm −1 , the film-forming composition comprising a film-forming material contained in the composition in an amount sufficient for the composition to have a solids content of at least 6% by weight, the film-forming material having a molecular weight such that the film-forming material has a viscosity of less than about 500 cP when present in a 3% by weight aqueous solution at 25° C., the treated areas having a permeability up to about 40 Coresta, the treated areas reducing ignition proclivity of a cigarette incorporating the wrapper, the untreated areas of the paper wrapper having a permeability of about 55 Coresta to about 110 Coresta.
2. A process as defined in claim 1 , wherein the film-forming material comprises an alginate.
3. A process as defined in claim 2 , wherein the alginate is a sodium alginate.
4. A process as defined in claim 1 , wherein the film-forming material is present in the composition such that the composition has a solids content of at least 10% by weight.
5. A process as defined in claim 1 , wherein the film-forming material has a viscosity of less than about 250 cP when present in a 3% by weight solution at 25° C.
6. A process as defined in claim 1 , wherein the film-forming material has a viscosity of less than about 100 cP when present in a 3% by weight solution at 25° C.
7. A process as defined in claim 1 , wherein the film-forming material is a material selected from the group consisting of guar gum, pectin, polyvinyl alcohol, a cellulose derivative, starch, a starch derivative, and mixtures thereof.
8. A process as defined in claim 1 , wherein the treated areas have a BMI of from about 1 cm −1 to about 5 cm −1 .
9. A process as defined in claim 1 , wherein the film-forming composition is printed onto the paper wrapper.
10. A process as defined in claim 9 , wherein the film-forming composition is printed onto the paper wrapper in a multi-pass operation.
11. A process as defined in claim 1 , wherein the treated areas comprise a plurality of discrete circumferential bands disposed longitudinally along the paper wrapper, the bands having a width of greater than 4 mm, the bands being spaced from each other from a distance of from about 10 mm to about 40 mm.
12. A process as defined in claim 1 , wherein the film-forming composition is applied to the paper wrapper using gravure printing.
13. A process as defined in claim 1 , wherein the film-forming composition is applied to the paper wrapper in the treated discrete areas in an amount up to about 30% by weight based upon the weight of the paper wrapper.
14. A process as defined in claim 1 , wherein the treated discrete areas have a BMI of less than about 3 cm −1 .
15. A process as defined in claim 1 , further comprising the step of drying the paper wrapper after the film-forming composition has been applied.
16. A process as defined in claim 1 , further comprising the step of incorporating the paper wrapper into a smoking article, the smoking article comprising a column of a smokable tobacco, the column of the smokable tobacco being surrounded by the paper wrapper.
17. A process as defined in claim 1 , wherein the filler contained in the paper web comprises calcium carbonate or magnesium oxide, the filler being present in the paper web in an amount from about 10% by weight to about 40% by weight.
18. A process as defined in claim 1 , wherein the film-forming composition comprises an aqueous composition.
19. A process as defined in claim 1 , wherein the film-forming composition has a viscosity of greater than about 800 cP.
20. A process as defined in claim 1 , wherein the film-forming composition has a viscosity of greater than about 1000 cP.
21. A process as defined in claim 1 , wherein the film-forming material comprises starch or a starch derivative.
22. A process for producing a paper wrapper having reduced ignition proclivity characteristics when incorporated into a smoking article comprising:
printing a film-forming composition on a paper wrapper at particular locations to form treated discrete areas on the wrapper, the paper wrapper comprised of a paper web, the paper web containing a filler, the treated discrete areas being separated by untreated areas, the treated discrete areas having a BMI within a range sufficient to reduce the ignition proclivity characteristics of a smoking article without causing the smoking article to self extinguish in a free burn state, the BMI of the treated discrete areas being less than about 5 cm −1 , the film-forming composition comprising an aqueous solution containing an alginate, the solution containing the alginate in an amount so as to have a solids content of at least 8% by weight, the alginate having a molecular weight such that the film-forming material has a viscosity of less than about 250 cP when present in a 3% by weight aqueous solution at 25° C., the treated areas forming circumferential bands along the length of the paper wrapper when incorporated into a smoking article, the treated areas having a permeability of less than about 40 Coresta, the film-forming composition being applied to the paper wrapper in the treated areas in an amount of from about 2% to about 20% by weight based upon the weight of the wrapper, the untreated areas of the paper wrapper having a permeability of about 55 Coresta to about 110 Coresta.
23. A process as defined in claim 22 , wherein the treated discrete areas have a BMI of less than about 3 cm −1 .
24. A process as defined in claim 22 , further comprising the step of incorporating the paper wrapper into a smoking article, the smoking article comprising a column of a smokable tobacco, the column of the smokable tobacco being surrounded by the paper wrapper.
25. A process as defined in claim 22 , wherein the film-forming composition has a viscosity of greater than about 800 cP.
26. A process as defined in claim 22 , wherein the film-forming composition has a viscosity of greater than about 1000 cP.
27. A process as defined in claim 22 , wherein the treated areas comprise a plurality of discrete circumferential bands disposed longitudinally along the paper wrapper, the bands having a width of greater than 4 mm, the bands being spaced from each other from a distance of from about 10 mm to about 40 mm.
28. A process as defined in claim 22 , wherein the film-forming material comprises starch or a starch derivative.