Low ignition propensity (LIP) paper smoking articles

Abstract

Apparatus for producing low ignition propensity (“LIP”) smoking articles provides independent control of the belt drive transport speed and the cutting head rotational speed in dependence on the relative position of the cutting head blades to the position of the continuous tobacco column on the tape drive, by detecting the presence of synchronizing marks disposed on the outer surface of the tobacco column LIP paper wrapper, thereby controlling cutting of the continuous column to provide registration of the LIP paper's LP bands to their designated location within the finished article's tobacco column.

Description

TECHNICAL FIELD [0001] This invention relates to the manufacture of smoking articles, and more particularly to the manufacture of low ignition propensity smoking articles which are designed to self extinguish if left unattended. BACKGROUND ART [0002] With smoking articles, such as cigarettes, the paper wrapper is important to the overall quality of the cigarette. The paper affects the taste and ash appearance of the cigarette, and the paper porosity (i.e. the oxygen permeability) determines the rate and direction of airflow through the cigarette. Higher porosity papers produce lower tar and nicotine yields to the user by increasing the heat and burn rate of the cigarette without altering the flavor. This has led to the use of higher porosity papers by cigarette manufacturers. Today's conventional cigarette papers have porosity levels on the order of 40 to 50 Coresta units (cu), which are expressed as: cu=cc / minute / cm2 at 100 mb pressure (1000 mm water). [0003] While these high poros...

AI Technical Summary

Benefits of technology

[0011] According to the first aspect, improved LIP paper tobacco wrapper has LP bands disposed thereon the width of the paper, the being bands arranged in interleaved fashion with untreated areas in a longitudinally extending array of consecutive panels, each panel extending horizontally a panel length which substantially equals the desired length of the tobacco column of the smoking article formed by the LP paper, the LIP paper further including synchronizing marks disposed longitudinally thereon, in the direction of the panels, and at mark interval spacing which is proportional to the panel length, each synchronizing mark thereby located on the LIP paper in known axial relation to the panel boundaries, the synchronizing marks being capable of detection by the LIP smoking article manufacturing apparatus to permit the apparatus to synchronize cutting of the continuous LIP wrapped tobacco column at locations proximate to the panel boundaries, thereby to provide registration of each panel to the cut length of article tobacco column.

[0017] The present invention provides for controlled placement of the LP bands of the LIP paper along the cigarette's rod length, so as to provide repeatable registration of the LP bands and a consistent appearance to the finished cigarette product. The invention provides this with no visible indications remaining on the LIP paper, other than that resulting from the caps LP bands themselves.

Problems solved by technology

While these high porosity papers introduce air into the smoke stream to lower the concentration of gases and particulate matter in the smoke, an unintended result of their high oxygen permeability is that, when lighted, they can burn their entire length without the user having to draw smoke or the cigarette having to be placed in a free burn environment.

As a result, if left unattended, they can ignite flammable objects they come in contact with.

Also, since the wet slurry processes of forming the LP bands cannot be performed during the manufacture of the smoking article due to the likelihood of the wet paper breaking when placed under tension, the LIP smoking article is preferably manufactured using pre-manufactured LIP wrapping paper.

Since conventional smoking articles do not have this constraint, conventional smoking article manufacturing equipment is not capable of performing the required synchronization.

There are also no prior art methods for achieving this pattern length to tobacco column length registration.

It is apparent, therefore, that there is a need for a method and apparatus capable of providing accurate and repeatable placement of the LP bands within the tobacco column, and that conventional article manufacturing methods and apparatus are not capable of providing this.

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