FIELD OF THE INVENTION
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The present invention relates to a smoking article, for example a Heat-Not-Burn (HNB) device.
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Heat-Not-Burn (HNB) devices which are sometimes also referred to as non-combustion type smoking articles are being developed as a possible alternative to conventional cigarettes. HNB technology generates an aerosol by heating rather than burning tobacco and/or other smoking materials. Examples of coaxial HNB cigarettes are known from US Publication No. US 2005/0066985 and U.S. Pat. No. 5,265,626.
A disadvantage of known HNB products, for example Premier™ and Eclipse™ introduced by RJ Reynolds Tobacco Company is that they do not provide a similar user experience to conventional tobacco burning cigarettes. For example, the above HNB products look, feel and taste different to conventional cigarettes.
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According to the invention there is provided a smoking article, comprising: an inner rod of aerosol generating material; a inner wrapper, circumscribing the inner rod; and a combustible outer rod circumscribing the inner wrapper, wherein combustion of the outer rod is arranged to heat the inner rod to generate an aerosol for delivery through the inner rod.
Advantageously the aerosol is generated through heating but not burning the inner rod. In addition, combustion of the outer rod provides a visual indictor of consumption to the user.
Conveniently, the inner wrapper is substantially non-flammable. This can help prevent combustion of the inner rod.
The inner wrapper may be substantially non-permeable.
Preferably, the smoking article comprises a central low impedance path which is surrounded by a high impedance path.
Typically, the outer rod is of a higher density than the inner rod creating a pressure drop to control airflow through the inner rod.
Preferably, the smoking article further comprises a filter arranged to create a pressure drop by having portions of varying density in the filter to control airflow through the inner rod.
Optionally, airflow is restricted to flow through the inner rod only.
The inner wrapper may comprise bands, spaced along the length of the inner wrapper, wherein the bands are arranged to enable the inner rod to break and be disposed of along with ash from the outer rod.
The inner rod can have break portions, spaced along the length of the inner rod, the break portions becoming brittle when heated to enable the inner rod to break and be disposed of along with ash from the outer rod.
Typically, the aerosol generating material and/or the combustible material of the outer rod is tobacco or a tobacco substitute.
The aerosol generating material can include additives, including humectants, and may be substantially non-combustible. Advantageously, humectants may i) prevent or arrest combustion of the inner rod, ii) contribute to the flavour and sensory experience for the consumer, and iii) prevent the aerosol generating material from drying out.
The invention also includes a method of manufacturing a smoking article described above.
BRIEF DESCRIPTION OF THE DRAWINGS
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Embodiments of the present invention will now be described by way of illustrative example with reference to the accompanying drawings, in which:
FIG. 1a is a perspective view of a coaxial smoking article showing internal features of a body of the smoking article, including an inner rod and inner wrapper, in dashed lines.
FIG. 1b is transverse cross-sectional view of the body of coaxial smoking article of FIG. 1;
FIG. 2 is a longitudinal cross-sectional view of the coaxial smoking article of FIG. 1, showing an expanded view of a coaxial rod arrangement of the body;
FIG. 3a is the longitudinal cross-sectional view of FIG. 2, showing an expanded view of a filter arrangement for the smoking article;
FIG. 3b is the longitudinal cross-sectional view of FIG. 2, showing an expanded view of an alternative filter arrangement to that of FIG. 3a; and
FIG. 4 is a longitudinal cross-sectional view of the coaxial smoking article of FIG. 1, part way though consumption.
FIGS. 1a, 1b and 2 show a coaxial smoking article 1, referred to hereinafter as a cigarette, that has a body 2 and a filter 4. The body 2 of the cigarette is of coaxial construction and has an inner rod 6, an inner wrapper 8, an outer rod 10 and an outer wrapper 12.
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The inner rod 6 of the coaxial arrangement contains tobacco or a tobacco substitute. The inner rod 6 is heated during use to cause volatilisation of low boiling point components within the product, while avoiding pyrolysis or combustion of the tobacco or volatiles. This volatilisation leads to the creation of a vapour which is drawn through the cigarette 1 and is then condensed into an aerosol and inhaled by the consumer. The volatilised components include water, nicotine, humectants and light volatiles.
The inner rod 6 preferably contains a blend of tobacco or tobacco substitute which has been specifically formulated for the coaxial HNB cigarette although existing tobacco blends or tobacco substitutes may be used for the inner rod 6.
The tobacco blend of one embodiment may include additives which are included to enhance the sensorial attributes of the aerosol. For example, additives such as propylene glycol, glycerol or triacetin may be added to the tobacco blend.