Note: Descriptions are shown in the official language in which they were submitted.
CA 02751670 2011-08-05
20/08 2010 11:56 FAX VENNER SHIPLEY 401 n 4
PCT/EP 2010/050 803 - 20-08-2010
-1-
Smoking Articles and Method for Manufacturing Smoking Articles
Field of the Invention
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 i
smoking article having a reduced ignition prc;opensity.
Background to the Invention
Many different methods have been suggested for manufacturing smoking articles
such a s 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 tecognised that the constitution of the
wrapper
1-5- 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.
One method for snaking wrappers for smoki~zg articles having reduced ignition
propensity is to add bands of paper to the wrapping paper, wherein the
composition'
of the wrapper and the band paper are selected to yield a composite paper
having
the desired burn rate, as disclosed in EP 0 483998 and EP 0 202550.
Another method is to provide bands of lesser and greater air permeability by
calenderhig the paper, for example, as disclosed in U5 4,945,932.
A further method is to chemically treat the paper by applying a burn retardant
material to a cigatette paper. The burn retardant additive is typically
applied in a
pattern such as bands which, in the final assembled cigarette, extend around
the
circumference of the cigarette- A method for manufacturing a suitable such
banded
paper is disclosed in W 098/01233. Such banded papers have a number of
drawbacks. 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
Duration: 20.08.2010 13:01:34 - 20.08.2010 13:03:12. This page 14 of AMENDED
SHEET2010 13:03:00
Received at the EPO on Aug 20, 2010 13:03:12. Page 14 of 16
A
CA 02751670 2011-08-05
2Q/08 2010 11:58 FAX VENNER SHIPLEY IN15
PCT/EP 2010/050 803.- 20-08-2010
sequence for applying the bandcd additivc and drying the paper prior to
manufacturing the cigarettes in the usual way. Furthermore, when the paper is
used.
to manufacture the cigarettes, the bands are randomly situated along the
length of
the cigarette. 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 !i
positions along the cigarette.
A further method of manufacturing a low ignition propensity cigarette is to
use a it
non banded paper of ultra low permeability, typically approximately 5 Coresta
Units
(CU). These non banded papers ate less expensive than the banded papers but
also
have a number of drawbacks. Firstly, conversely to the banded papers, the self
extinguishing element is constant along the whole length of the paper and
therefore
the cigarette may self extinguish at any point. Furthermore, the extremely low
permeability means that the smoulder rate is very low all the way through the
smoking and rherefore, to deliver an overall tar yield, the rat per puff is
low. The
low natural permeability of the paper futthcr means that little diffusion of
carbon
monoxide can occur from the rod, such that the carbon monoxide/tar ratio of
the
smoke is generally high. Addition of ventilation, for example via
Electrostatic
perforation (EP) does not significantly increase the burn rate but dilutes the
smoke
yield pet puff. Furthermore, it has been found that relatively small changes
in the
physical and chemical properties of the paper can affect its ability to pass
the lit
ignition propensity test (LIl.ST), and therefore the CU specifications for low
permeability papers will be tequired to be set at a lower value than optimal
so as to 11
ensure compliance to pass the LIPT.
Attempts have been made to apply banding during the cigarette making process.
This allows the bands to be positioned at desired locations by synchronising
the
application of the bands with cutting of the rod formed when the tobacco is
wrapped in the banded paper. This overcomes the problem of positioning of the
it
Duration: 20.08.2010 13:01:34 - 20.08.2010 13:03:12. This page 15 of AMENDED
SHEET2010 13:03:08
Received at the EPO on Aug 20, 2010 13:03:12. Page 15 of 16
CA 02751670 2011-08-05
WO 2010/097258 PCT/EP2010/050803
-3-
bands found with the pre-manufactured banded papers. This on line application
of
banding is disclosed in WO 2004/057986 and US 2004/0261805. 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
90 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. Various heaters can be included in the machine to assist
in
drying the paper but to allow time for these to properly dry the paper, the
machine
must be slowed. The slowing of the machine may also alleviate problems with
tearing, but this decreases production efficiency.
Summary of the Invention
The present invention provides a method of manufacturing a plurality of
smoking
articles, comprising:
providing a wrapping paper having a permeability of less than 15 CU;
applying a burn retardant additive material in a predetermined pattern to the
wrapping paper;
wrapping the wrapping paper about a tobacco material to form a wrapped
rod; and
cutting the wrapped rod to form the plurality of smoking articles.
The present invention also provides a smoking article, comprising:
a rod of tobacco material;
a wrapping paper surrounding the rod of tobacco material, the wrapping
paper having a pattern of a burn retardant additive material applied thereto,
the
wrapping paper having 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.
CA 02751670 2011-08-05
WO 2010/097258 PCT/EP2010/050803
-4-
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
/0 permeability paper enables a degree of online control to be maintained, for
instance
to take account of variations in paper specification and tobacco density.
Preferably, the permeability of the wrapping paper is 5 to 10 CU.
In the method of the present invention, preferably the applying of the burn
retardant additive material is synchronised with the cutting of the wrapped
rod such
that the pattern is located in a predetermined position with respect to an end
of
each smoking article. Preferably the wrapped rod is cut so that the pattern is
located in substantially the same position on each smoking article. Preferably
the
rod is cut so that the pattern covers 25-50% of the length of the smoking
article at
one end of the smoking article. Preferably, a filter is attached to the end of
the
smoking article at which the pattern is formed.
Preferably, the pattern comprises a plurality of bands which, in the smoking
articles,
extend around the circumference of the smoking articles.
Preferably, in the area of the paper to which the pattern is applied, the burn
retardant additive material adds less than 10% to the weight of the paper,
preferably
less than 8%. More preferably the burn retardant additive material adds 0-5%
to the
weight of the paper, most preferably 2-5%.
Preferably, the burn retardant additive includes one or more of the following:
gums
such as guar gum, gum arabic etc, adhesives such as starches, hot melt
adhesives,
CA 02751670 2011-08-05
WO 2010/097258 PCT/EP2010/050803
5-
PVA etc, organic salts such as alginates and citrates, inorganic salts such as
chlorides (eg KCL) and oxides (eg MgO).
The pattern may be applied by printing or spraying.
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
/0 minimal modification to making equipment is needed and manufacturing
efficiency
is not impaired.
Brief Description of the Drawing
Preferred embodiments of the present invention will now be described with
reference to the accompanying drawings, in which:
Figure 1 is a schematic illustration of a cigarette making machine suitable
for
carrying out the method of the present invention; and
Figure 2 shows a smoking article according to an embodiment of the present
invention.
Detailed Description
Figure 1 shows a cigarette making apparatus 10 of a type known in the art,
which has been
modified to apply a burn retardant additive material to a wrapping paper prior
to forming
the wrapping paper into cigarettes. The cigarette making apparatus 10 includes
a source of
tobacco material 20 which is provided to chimney region 16 where it is blown
upwards by
air stream 22 onto a lower outside surface of endless conveyor system 28. The
endless
conveyor system 28 includes a porous belt 32 having a low pressure region 41
into which
the tobacco material 20 is drawn, wherein the porous belt 32 retains the
tobacco material
against the bottom of the conveyor system 28 to form a stream of tobacco
material
conveyed towards a garniture section 45.
CA 02751670 2011-08-05
WO 2010/097258 PCT/EP2010/050803
-6-
A paper supply section 8 is provided to supply a continuous web of paper
wrapping
material 55 from a roll 58 through a series of rollers and guide posts 60, 61
to the garniture
section 45 where the wrapping material 55 is wrapped around the tobacco
material 20 to
form a continuous wrapped rod. Typically, the paper supply section 8 will
include a
printing device 65 for printing a serial number or indicia onto the paper at
predetermined
intervals. In the apparatus shown in Figure 1, the paper supply section 8 has
additionally
been modified to supply a burn retardant additive material in a pre-determined
pattern to
the wrapping paper 55. The burn retardant additive material is applied by the
applicator
section 70 which comprises a reservoir 85 of LIP solution, a pickup roller 78
and a transfer
90 roller 82. The pickup roller has a series of grooves cut into it in the
pattern which is to be
applied to the paper 55 and picks up LIP solution from the reservoir 85. The
solution is
picked up in the grooves and transferred to the transfer roller 82 as a
pattern of solution.
The transfer roller 82 transfers the pattern to the paper 55. The pattern is
typically a series
of spaced apart bands. The bands will preferably run substantially across the
full width of
the paper (may have small gap for adhesive sealing) and be 1mm or more wide
(preferably
2-5mm). The LIP solution in the reservoir 85 may be a liquid or paste
containing burn
retardant additives such as gums such as guar gum, gum arabic etc, adhesives
such as
starches, hot melt adhesives, PVA etc, organic salts such as alginates and
citrates,
or inorganic salts such as chlorides (eg KCL) and oxides (eg MgO). Optionally,
the
burn retardant material is maintained at a temperature above ambient via
heating of the
reservoir and/or application system.
Optionally, the paper 55 may be heated prior to passing through the applicator
section 70,
to assist in drying the paper. A further heater 120, such as an infra red
heater, may heat the
paper after the pattern has been applied.
The applicator section 70 is arranged to apply the burn retardant additive
material to the
side of the paper 50 which will be the inside of the wrapping material i.e.
facing the tobacco
when the wrapping material is wrapped around the tobacco material 20 in the
garniture
section 45.
The garniture section 45 includes a garniture conveyor belt 130 driven by a
roller
132.
CA 02751670 2011-08-05
WO 2010/097258 PCT/EP2010/050803
-7-
According to the present invention, the wrapping material 55 is paper having a
starting permeability of less than 15 CU, preferably 5 to 10 CU. The use of
low
permeability paper means that the finished cigarette already has more of a
tendency
to self extinguish even without the burn retardant additive, although without
the
burn retardant additive the self extinguishing properties would not be
sufficient to
pass a Lit Ignition Propensity Test. However, the low permeability paper does
allow the quantity of burn retardant additive which it is necessary to add to
the
paper to be reduced, to a level such that, in the final paper, the burn
retardant
/0 additive adds less than 8%, preferably 0 to 5%, more preferably 2 to 5% to
the
weight of the paper.
Due to the reduced amount of burn retardant, drying of the paper 55 is
improved so
that heater 120 may not be required. If heater 120 is not required, it is
preferable
that the applicator section 70 be located as close as possible to the entry of
the
garniture section 45 to prevent build up or loss of the LIP solution as the
paper 55
passes through further rollers before being formed into a wrapped rod in the
garniture section 45.
In the garniture section 45, the garniture conveyor belt 130 conveys the paper
55
under a rail assembly 140 through a garniture entrance cone 144. The tobacco
material 20 is carried by the conveyor belt 32 and deposited on the paper web
55
and the finger rail assembly 140 and garniture entrance cone 144 guide the
filler
material 20 from the porous conveyor belt 32 into the garniture section 45.
The
garniture section 45 further includes a tongue 160 positioned over the path of
the
garniture conveyor belt 132. The tongue 160 constricts the tobacco filler 20
on the
wrapping paper 55 so that the tongue 160 and the conveyor belt 130 define a
passage which decreases in cross section so that the tobacco material is
compressed
to form a tobacco material rod 170. A folding mechanism 180 located downstream
from the tongue 160 compresses the tobacco material 20 further and folds the
paper
web 55 around the rod 170. An adhesive applicator 184 applies adhesive to an
edge
of the paper web and secures the edge to an overlapping portion of the paper
web
55. The continuous rod 170 then passes to a cutting section 186 where it is
divided
CA 02751670 2011-08-05
WO 2010/097258 PCT/EP2010/050803
8-
by a knife into a plurality of smoking articles 190,191. The knife is located
within
knife support 192.
The knife is synchronised with the applicator section 70 so that the rod 170
is cut at
positions such that the pattern of burn retardant material on the wrapping
paper is
located at a particular position on each of the plurality of smoking articles
190, 191.
Particularly, the pattern may be applied at one end of each rod, preferably
extending
over the first 25-50% of the length of the rod. A filter is subsequently
applied to
the end having the pattern of burn retardant material, and affixed with a
tipping
paper in a manner known in the art.
The synchronisation of the knife which cuts the rod into sections and the
positioning of bands is achieved via mechanical or electrical means. In the
mechanical method, the gearing that moves the knife is joined directly via a
series of
linkages to the additive applicator. In the electrical method, an electrical
pulse,
timed by the knife is used to time the applicator mechanism.
Figure 2 shows a smoking article I according to the present invention, which
has
been manufactured using the process described above. The smoking article 1
comprises a wrapped rod 2 of tobacco material with a filter 3 at one end. The
filter
is attached to the wrapped rod 2 with tipping paper and the wrapped rod 2
includes
a tobacco core surrounded by a wrapping paper. The wrapping paper has a
pattern
of a burn retardant additive material applied thereto, the pattern comprising
a
plurality of spaced apart bands 4. The pattern is located at the filter end of
the rod
2. The bands 4 will preferably be 1mm or more wide (preferably 2-5mm) and the
length 12
of the wrapped rod 2 to which the bands 4 are applied is 25 to 50% of the
length 1, of the
whole wrapped rod 2.
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.
Preferably the paper has a permeability of 5 to 10 CU in areas without the
burn
retardant additive.
