Note: Descriptions are shown in the official language in which they were submitted.
2013427
IMPROVEMENTS RELATING TO SMOKING ARTICLES
The invention the subject of this application
relates to cigarettes and similar smoking articles.
It is an object of the subject invention to provide
a cigarette which is of a low tar delivery but which is
sensorily acceptable to the smoker.
The subject invention provides a smoking article
comprising a tobacco rod, which comprises cut expanded
tobacco and a paper wrapper circumscribing said tobacco,
a major portion at least of said tobacco having been
treated with a humectant to provide a loading level of
said humectant of 4~ to 15% by weight of said tobacco,
the packing density of said tobacco rod not exceeding 210
mg/cc and wherein, when said article is smoked under
standard machine smoking conditions, the particulate
matter delivery on a water, nicotine and humectant free
basis to nicotine delivery (PMWNHF) is not more than 6 to
1.
Suitably, the loading level of the humectant on the
tobacco is not less than 5% and does not exceed 12%.
More suitably, the loading level is in the range of 7 -
10%, 9% for example.
The humectant is suitably one or more of glycerol,
propylene glycol, sorbitol and diethylene glycol.
Advantageously, the humectant is applied to the
tobacco prior to the tobacco being subjected to an
expansion process. The loading level of the humectant on
the tobacco prior to expansion may be in a range of about
5% to about 20% in order to result in a post expansion
level of 4% to 15%.
We have found that if the humectant is applied to
the tobacco before rather than after the tobacco is
subjected to the expansion process, a reduction in
tobacco strand length during the process is avoided.
Further advantages
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of applying the humectant prior to expansion reside in the
avoidance of an undesirably high equilibrium moisture
content post expansion and the avoidance of a reduction in
the filling power of the expanded tobacco.
Suitably, the humectant is applied to the tobacco by
being sprayed thereon, advantageously in aqueous solution.
The humectant should, before the tobacco is subjected
to the expansion process, be distributed of the tobacco
with a significant degree of uniformity, which objective
may be furthered by tumbling the tobacco and/or allowing
the tobacco to stand in bulk for a sufficient time after
the application of the humectant.
Tobacco of smoking articles according to the subject
invention which is to be subjected to an expansion process
is suitably pre-conditioned to a moisture content in a
range of 22% to 30% and preferably to a moisture content
in a range of 26% to 30%.
Tobacco of smoking articles according to the subject
invention which is subjected to an expansion process may
be lamina and/or stem tobacco. The expanded tobacco
advantageously comprises a lamina tobacco the product of a
tobacco expansion process which is effective to provide a
high degree of expansion in tobacco subjected to the
process. High expansion processes are disclosed, for
example, in the specification of United States Reissue
Patent No. 30,693 and in United Kingdom Patent
Specifications Nos. 1,570,270 and 2 160 408A. By use of
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high expansion processes, tobacco expansion values, in
terms of filling value increase, of from about,
typically, 75~ and even up to about 125~ may be obtained.
Tobacco which has been subjected to a high expansion
process may have a bulk density of, for example, from
about 100 mg/cc to about 200 mg/cc, and preferably not
less than 150 mg/cc, as measured using a Borgwaldt
Densimeter.
A minor proportion of the smoking material of
smoking articles according to the subject invention may
take the form of reconstituted tobacco and/or tobacco
substitute material. Preferably though, the smoking
material should be wholly natural cut tobacco. It is
also preferable that the whole or a substantial
proportion of the cut tobacco of smoking articles
according to the subject invention should be expanded
tobacco and that the whole of this expanded tobacco
should have been treated with humectant prior to being
expanded. Suitably, at least 65~ of the tobacco is
treated expanded tobacco, and more suitably 70~ is
treated expanded tobacco.
The weight of the smoking material in a cigarette
according to the subject invention is suitably in a range
of 500 to 800 mg.
It is to be observed that when measurement is made
of the PMWNF delivery of a smoking article according to
the subject invention, the value obtained includes a
proportion of the humectant. It may thus be of interest
to express particulate matter delivery on a water
nicotine and humectant free basis (PMWNHF). The PMWNHF
to nicotine delivery ratio of smoking articles according
to the subject invention is not more than 6 to 1 and
preferably is in the region of about 5 to 1.
The humectant in the mainstream smoke of cigarettes
according to the subject invention, as measured under
standard machine smoking conditions, preferably forms not
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201~7
less than 15~, and more preferably not less than 20~, of
the mainstream PMWNF. Yet more preferably the mainstream
smoke humectant forms approximately 25~ of the mainstream
PMWNF. Suitably, the mainstream smoke humectant may also
be in the range 24~ to 26~, 24~ for example.
A burn retardant may be used in smoking articles in
accordance with the subject invention. The burn
retardant may be, for example, magnesium chloride, sodium
chloride, ammonium sulphate, ammonium lactate, or
mixtures thereof, applied to the smoking material.
In order to further the understanding of the subject
invention, examples according thereto will now be
described.
EXAMPLE 1
To a cut tobacco blend comprising 20~ water treated
stem, 40~ burley tobacco lamina and 40~ flue cured
tobacco lamina there was added glycerol at a 10~ loading
level and magnesium chloride at a 1~ loading level. The
blend was conditioned to 25~ moisture content, the blend
being thereafter subjected to a high level expansion
process. The glycerol loading on the expanded tobacco
was about 6~.
Using the thus obtained expanded tobacco, 24.75 mm
circumference cigarettes were made. Each cigarette
comprised a 64 mm long tobacco rod consisting of 100% of
the expanded tobacco and of wrapper of a standard
commercial cigarette paper. The packing density of the
tobacco in the tobacco rods was about 145 mg/cc. To each
of the tobacco rods there was attached, by a tipping
wrapper, a 20 mm long cellulose acetate filter plug. The
cigarettes were laser ventilated at the filters to
provide a ventilation value of 55~.
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These cigarettes were smoked under standard
(Coresta) machine smoking conditions according to which a
35 cm3 puff of two seconds duration is taken every minute
and were found to yield mainstream smoke component
deliveries
~r ~
_ ~.
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as follows.
Component Delivery (mg)
TPM 5.88
Nicotine 0.63
PMWNF 4.37
Glycerol 1.35
PMWNHF 3.02
It is thus to be observed that the PMWNHF to nicotine
ratio was 4.8. It may also be observed that the glycerol
delivery represented 31% of the PMWNF delivery.
It was found that when smoked under Coresta machine
smoking conditions, a commercially available cigarette,
Benson & Hedges Ultra (Trade Mark), of similar delivery,
i.e. 5.57 mg TPM, had a mainstream glycerol delivery of
O.44 mg, this representing 9.4 per cent of the PMWNF
delivery. The PMWNHF to nicotine ratio of the Ultra
cigarettes was 9.9.
In sensory panel smoking tests it was found that the
above detailed cigarettes according to the subject
invention exhibited sensory features superior to those of
the Ultra cigarettes.
EXAMPLE II
To a first cut tobacco blend comprising 65% flue
cured lamina and 35% burley lamina was added glycerol at a
6% loading level and ammonium lactate at a 2% loading
level. The blend was conditioned to a 30% moisture
content, the blend being thereafter subjected to the high
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level DIET expansion process. The glycerol loading level
on the expanded tobacco was 4.4%.
A second cut tobacco blend comprised 50% burley
lamina and 50% sun cured oriental lamina. The second
blend was not subjected to an expansion process.
The first and second blends were combined in the
proportions 70% first to 30% second and to the thus
obtained combined blend was added propylene glycol at a
1.5% loading level. Thus the total loading level of
humectant, glycerol plus propylene glycol, was 4.6%.
Using the tobacco of the combined blend 24.75 mm
circumference cigarettes were made. Each cigarette
comprised a 59 mm long tobacco rod and a standard
commercial cigarette paper. The packing density of the
tobacco in the rods was 190 mg/cc. To each of the rods
there was attached a 25 mm long dual filter comprising a 7
mm long section of crimped paper and an 18 mm long section
of cellulose acetate filtration material. The cigarettes
were laser ventilated at the cellulose acetate sections of
the filters to provide a ventilation of 60%.
When smoked under standard machine smoking
conditions, mainstream smoke component deliveries were
found to be as follows:
ComponentDelivery (mg)
TPM 6.79
Nicotine 0.84
PMWNF 5.43
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Component Delivery (mg)
Glycerol 1.00
Propylene glycol 0.28
PMWNHF 4.15
Thus the PMWNHF to nicotine ratio was 4.9 and
humectant represented 24% of the PMWNF delivery.
A commercially available cigarette of similar
delivery, namely Camel Lights (Trade Mark), was found to
have a mainstream glycerol delivery of 0.39 mg, this
representing 8% of the PMWNF delivery. The PMWNHF to
nicotine ratio of Camel Lights was 9.7.
EXAMPLE III
A cut tobacco blend comprised 25% burley lamina, 40%
flue cured lamina, 25% water treated stem and 10% sun
cured oriental lamina. To this blend was added glycerol
at a 10% loading level and magnesium chloride at a 1%
loading level. The blend was thereafter subjected to a
high level expansion process. The glycerol loading level
on the expanded tobacco was 8%.
Using the thus obtained tobacco cigarettes were made
which were to the same format as the cigarettes according
to the invention of Example I. When smoked under standard
machine smoking conditions, mainstream smoke component
deliveries were found to be as follows:
Component Delivery ~mg)
TPM 6.55
Nicotine 0.54
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Component Delivery (mg)
PMWNF 4.93
Glycerol 1.63
PMWNHF 3.30
Thus the PMWNHF to nicotine ratio was 6.1 and the
humectant represented 33~ of the PMWNF.
