Cigarette Paper

What is this patent about?

'677 is related to the field of cigarette paper manufacturing, specifically addressing the reduction of carbon monoxide (CO) in cigarette smoke without sacrificing the taste or other desirable properties of the cigarette. The background highlights the challenge of reducing the harmful gas phase, particularly CO, while maintaining the particle phase responsible for taste. Prior attempts to reduce CO, such as increasing air permeability, often negatively impacted the taste.

The underlying idea behind '677 is to modify the cigarette paper's pore structure to selectively enhance the diffusion of CO out of the cigarette. This is achieved by using a specific blend of fibers, particularly a high proportion of rag fibers (bast fibers or regenerated cellulose fibers), and subjecting them to an extremely fine fibrillation process during manufacturing. This fibrillation creates a larger number of smaller pores, facilitating CO diffusion without significantly affecting the diffusion of other smoke components.

The claims of '677 focus on a cigarette paper composition comprising fibrous materials based on rag fibers, burning additives, and fillers. A key aspect is the rag fiber content, ranging from 20 to 50% by weight of the paper's dry weight. Furthermore, the rag fibers and/or regenerated cellulose fibers must exhibit a degree of grinding of at least 85 SR (Schopper-Riegler), indicating the fineness of fibrillation.

In practice, the invention involves carefully controlling the grinding process of the rag fibers to achieve the desired level of fibrillation. This fine fibrillation increases the surface area of the fibers and promotes entanglement, resulting in a pore structure that favors CO diffusion. The fiber length ratio, measured by the fiber fraction R16, is also controlled to maintain the desired pore structure and ensure optimal CO reduction.

This approach differs from prior methods that primarily focused on increasing the overall air permeability of the cigarette paper. While increased air permeability does reduce CO, it also dilutes the smoke and affects the taste. By selectively enhancing CO diffusion through a tailored pore structure, '677 allows for a reduction in CO levels without significantly altering the taste or other desirable characteristics of the cigarette smoke. The use of specific fiber types and the control of their fibrillation are crucial to achieving this selective diffusion.