Smoking Articles and Method for Manufacturing Smoking Articles

Abstract

The invention relates to a method of manufacturing a plurality of smoking articles, comprising providing a wrapping paper having a permeability of less than 15 CU and applying a burn retardant additive material in a predetermined pattern to the wrapping paper. The wrapping paper is wrapped about a tobacco material to form a wrapped rod and the wrapped rod is cut to form the plurality of smoking articles. The invention also relates to a smoking article manufactured by the method, wherein the wrapping paper has a permeability of less than 15 CU in areas without the burn retardant additive and a lower permeability in areas where the additive is applied.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a method for making smoking articles, and more particularly a method for applying a burn retardant additive material to a wrapping paper prior to wrapping the wrapping paper about a tobacco material, to produce a smoking article having a reduced ignition propensity.BACKGROUND TO THE INVENTION[0002]Many different methods have been suggested for manufacturing smoking articles such as cigarettes having a reduced ignition propensity i.e. a tendency to self-extinguish when not drawn on by a smoker. The aim is that such cigarettes will self extinguish when dropped or left on a flammable substrate before igniting the flammable substrate. It has been recognised that the constitution of the wrapper has a significant effect on the burn rate of a cigarette and by modifying the wrapper by various methods, a self-extinguishing cigarette can be produced.[0003]One method for making wrappers for smoking articles having reduced ignition pr...

AI Technical Summary

Benefits of technology

[0016]The low permeability of the paper means that a smaller amount of burn retardant material needs to be added to obtain the required self-extinguishing effect. This reduces the problems associated with applying larger amounts of burn retardant material, such as tearing of the paper when it is damp. This means that the application of the burn retardant material can more easily be carried out in one continuous process with the cigarette manufacture. The requirement for heating / drying steps is reduced, although heating steps may still optionally be added before or after the application of the burn retardant additive. Furthermore, the reduction in the amount of burn retardant additive combined with the lower permeability paper enables a degree of online control to be maintained, for instance to take account of variations in paper specification and tobacco density.

[0024]Preferably, the additive is applied to the inner surface of the paper and is in liquid form with viscosity, type, temperature and level of additive applied such that additional heating to dry the paper is not required. In such case additive can be applied directly prior to the area where tobacco is added to the paper bed, such that minimal modification to making equipment is needed and manufacturing efficiency is not impaired.

Problems solved by technology

Firstly, the cost of such papers is typically four to five times the cost of standard cigarette paper.

This is due to the cost of the additive material and the additional manufacturing cost of providing a separate apparatus and processing sequence for applying the banded additive and drying the paper prior to manufacturing the cigarettes in the usual way.

It is most desirable for the bands only to occur in portions of the cigarettes close to the filter and it is undesirable for bands to occur at the other end of the cigarette which is the first to be smoked.

This is because it is desirable that the cigarette self extinguish towards the end of the smoking and undesirable for the cigarette to self extinguish during the first few millimetres of smoking.

When using banded papers, there is no way to ensure that the bands are positioned in particular positions along the cigarette.

Furthermore, the extremely low permeability means that the smoulder rate is very low all the way through the smoking and therefore, to deliver an overall tar yield, the tar per puff is low.

However, these processes have additional drawbacks which mean that no such system has yet been brought to commercial production.

One problem is in the drying of the paper once the burn retardant solution has been applied.

Firstly, this must be dried before the garniture section of the machine where the tobacco is wrapped in the paper, because if the paper is damp at this stage when it comes into contact with the tobacco then discolouration of the paper may occur.

Furthermore, the machines used for wrapping cigarettes, which may be modified to include a section for applying a burn retardant solution, apply significant tension to the paper and when the paper is damp its tensile strength is significantly reduced so that tearing of the paper easily occurs.

The slowing of the machine may also alleviate problems with tearing, but this decreases production efficiency.

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