U.S. patent application number 10/695495 was filed with the patent office on 2005-04-28 for apparatus for measuring a property of a cigarette paper wrapper and associated method.
This patent application is currently assigned to R. J. Reynolds Tobacco Company. Invention is credited to Caudle, Jason Craig, Norman, Alan Benson.
Application Number | 20050087202 10/695495 |
Document ID | / |
Family ID | 34522808 |
Filed Date | 2005-04-28 |
United States Patent
Application |
20050087202 |
Kind Code |
A1 |
Norman, Alan Benson ; et
al. |
April 28, 2005 |
Apparatus for measuring a property of a cigarette paper wrapper and
associated method
Abstract
An apparatus for measuring a property of a cigarette paper
wrapper is provided and includes a sampling device having a first
chamber portion capable of being engaged with a corresponding
second chamber portion to define a sampling area configured to
receive the wrapper such that the wrapper spans the sampling area
and separates the chamber portions. A first gas source supplies a
carrier gas to the first chamber portion and a second gas source
supplies a detectable gas to the second chamber portion. An
analyzer device in communication with the first chamber portion
receives a resultant gas flow that includes the carrier gas and any
of the detectable gas entering the first chamber portion through
the wrapper. The analyzer device is capable of determining an
amount of the detectable gas in the resultant gas flow so as to
thereby determine a property of the cigarette paper wrapper, such
as a diffusion coefficient with respect to the detectable gas. An
associated method is also provided.
Inventors: |
Norman, Alan Benson;
(Clemmons, NC) ; Caudle, Jason Craig; (Pfafftown,
NC) |
Correspondence
Address: |
ALSTON & BIRD LLP
BANK OF AMERICA PLAZA
101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
R. J. Reynolds Tobacco
Company
|
Family ID: |
34522808 |
Appl. No.: |
10/695495 |
Filed: |
October 28, 2003 |
Current U.S.
Class: |
131/280 ;
131/908 |
Current CPC
Class: |
G01N 2015/084 20130101;
G01N 2013/003 20130101; G01N 13/00 20130101 |
Class at
Publication: |
131/280 ;
131/908 |
International
Class: |
A24C 005/32 |
Claims
That which is claimed:
1. An apparatus adapted to measure a property of a cigarette paper
wrapper, said apparatus comprising: a sampling device defining a
first chamber portion and a corresponding second chamber portion,
the first and second chamber portions engaging at and defining a
sampling area, the sampling device being configured to receive the
cigarette paper wrapper such that the cigarette paper wrapper spans
the sampling area and separates the first chamber portion from the
second chamber portion; a first gas source configured to supply a
regulated flow of a carrier gas to the first chamber portion; a
second gas source configured to supply a regulated flow of a
detectable gas to the second chamber portion; and an analyzer
device in communication with the first chamber portion and
configured to receive a resultant gas flow, the resultant gas flow
including the carrier gas and any of the detectable gas entering
the first chamber portion through the cigarette paper wrapper, the
analyzer device being further configured to be capable of
determining an amount of the detectable gas in the resultant gas
flow so as to thereby determine a property of the cigarette paper
wrapper.
2. An apparatus according to claim 1 further comprising a mass flow
meter operably engaged between each of the first and second gas
sources and the first and second chamber portions, respectively,
the respective mass flow sensors being adjustable to regulate the
flows of the carrier gas and the detectable gas such that
substantially equal mass flows thereof are supplied to the first
and second chamber portions, respectively.
3. An apparatus according to claim 1 wherein the cigarette paper
wrapper is provided as a roll of paper wrapper having regularly
repeating contiguous first and second bands, each band having a
defined area and the first band and the second band having
different values of a common property, and the sampling device is
further configured such that the sampling area is smaller than the
respective defined areas of the first and second bands.
4. An apparatus according to claim 3 further comprising an
advancement device configured to selectively advance the paper
wrapper from the roll and through the sampling device.
5. An apparatus according to claim 4 further comprising a sensor
operably engaged with the advancement device and configured to be
capable of directing the advancement device to selectively stop the
advancement of the paper wrapper through the sampling device such
that only one of the first and second bands spans the sampling
area.
6. An apparatus according to claim 5 further comprising a sensor
operably engaged with at least the analyzer device and configured
to direct the analyzer device to determine the amount of the
detectable gas in the resultant gas flow at least when the
advancement of the paper wrapper through the sampling device is
stopped and only one of the first and second bands spans the
sampling area.
7. An apparatus according to claim 1 wherein the analyzer device is
further configured to be capable of determining a diffusion
coefficient of the cigarette paper wrapper with respect to the
detectable gas.
8. An apparatus according to claim 1 wherein the carrier gas is a
substantially inert gas.
9. An apparatus according to claim 1 wherein the detectable gas is
substantially harmless and capable of being released to atmosphere
from the second chamber portion.
10. An apparatus according to claim 1 wherein the analyzer device
is further configured to determine when the amount of the
detectable gas in the resultant gas flow reaches an
equilibrium.
11. A method of measuring a property of a cigarette paper wrapper,
said method comprising: receiving a cigarette paper wrapper in a
sampling device defining a first chamber portion and a
corresponding second chamber portion, the first and second chamber
portions engaging at and defining a sampling area, the sampling
device being configured to receive the cigarette paper wrapper such
that the cigarette paper wrapper spans the sampling area and
separates the first chamber portion from the second chamber
portion; supplying a regulated flow of a carrier gas to the first
chamber portion; supplying a regulated flow of a detectable gas to
the second chamber portion; receiving a resultant gas flow at an
analyzer device in communication with the first chamber portion,
the resultant gas flow including the carrier gas and any of the
detectable gas entering the first chamber portion through the
cigarette paper wrapper; and determining, with the analyzer device,
an amount of the detectable gas in the resultant gas flow so as to
thereby determine a property of the cigarette paper wrapper.
12. A method according to claim 11 further comprising regulating
the flows of the carrier gas and the detectable gas with a mass
flow meter operably engaged between each of the first and second
gas sources and the first and second chamber portions,
respectively, such that substantially equal mass flows of the
carrier and detectable gases are supplied to the first and second
chamber portions, respectively.
13. A method according to claim 11 further comprising supplying the
cigarette paper wrapper as a roll of paper wrapper having regularly
repeating contiguous first and second bands, each band having a
defined area and the first band and the second band having
different values of a common property.
14. A method according to claim 13 wherein receiving the cigarette
paper wrapper in the sampling device further comprises receiving
the cigarette paper wrapper in a sampling device having a sampling
area is smaller than the respective defined areas of the first and
second bands.
15. A method according to claim 13 further comprising selectively
advancing the paper wrapper from the roll and through the sampling
device with an advancement device.
16. A method according to claim 15 further comprising directing the
advancement device to selectively stop the advancement of the paper
wrapper through the sampling device, with a sensor operably engaged
with the advancement device, such that only one of the first and
second bands spans the sampling area.
17. A method according to claim 16 further comprising directing the
analyzer device to determine the amount of the detectable gas in
the resultant gas flow, with a sensor operably engaged with at
least the analyzer device, at least when the advancement of the
paper wrapper through the sampling device is stopped and only one
of the first and second bands spans the sampling area.
18. A method according to claim 11 wherein determining an amount of
the detectable gas in the resultant gas flow further comprises
determining an amount of the detectable gas in the resultant gas
flow so as to determine a diffusion coefficient of the cigarette
paper wrapper with respect to the detectable gas.
19. A method according to claim 11 wherein supplying a regulated
flow of a carrier gas further comprises supplying a regulated flow
of a substantially inert gas.
20. A method according to claim 11 wherein supplying a regulated
flow of a detectable gas further comprises supplying a regulated
flow of a substantially harmless gas capable of being released to
atmosphere from the second chamber portion.
21. A method according to claim 11 wherein determining an amount of
the detectable gas in the resultant gas flow further comprises
determining an amount of the detectable gas in the resultant gas
flow when the amount of the detectable gas in the resultant gas
flow reaches an equilibrium.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to smoking articles and, more
particularly, to an apparatus for measuring a property of a paper
material suitable for use as components of such smoking
articles.
[0003] 2. Description of Related Art
[0004] Popular smoking articles, such as cigarettes, have a
substantially cylindrical rod shaped structure and include a
charge, roll or column of smokable material such as shredded
tobacco (e.g., in cut filler form) surrounded by a paper wrapper
thereby forming a so-called "tobacco rod." Normally, a cigarette
has a cylindrical filter element aligned in an end-to-end
relationship with the tobacco rod. Typically, a filter element
comprises plasticized cellulose acetate tow circumscribed by a
paper material known as "plug wrap." Certain cigarettes incorporate
a filter element having multiple segments, and one of those
segments can comprise activated charcoal particles. Typically, the
filter element is attached to one end of the tobacco rod using a
circumscribing wrapping material known as "tipping paper." It also
has become desirable to perforate the tipping material and plug
wrap, in order to provide dilution of drawn mainstream smoke with
ambient air. A cigarette is employed by a smoker by lighting one
end thereof and burning the tobacco rod. The smoker then receives
mainstream smoke into his/her mouth by drawing on the opposite end
(e.g., the filter end) of the cigarette.
[0005] Numerous references propose various types of cigarettes
possessing various types of paper wrapping materials. See, for
example, U.S. Pat. No. 1,909,924 to Schweitzer; U.S. Pat. No.
4,489,650 to Weinert; U.S. Pat. No. 3,030,963 to Cohn; U.S. Pat.
No. 4,146,040 to Cohn; U.S. Pat. No. 4,489,738 to Simon; U.S. Pat.
No. 4,615,345 to Durocher; U.S. Pat. No. 4,607,647 to Dashley; U.S.
Pat. No. 5,060,675 to Milford et al.; U.S. Pat. No. 4,924,888 to
Perfetti et al.; U.S. Pat. No. 5,143,098 to Rogers et al.; U.S.
Pat. No. 4,998,543 to Goodman; U.S. Pat. No. 5,220,930 to Gentry;
and U.S. Pat. No. 5,271,419 to Arzonico et al. Some paper wrapping
materials are so-called "banded papers" and possess segments
defined by the composition, location and properties of the various
materials within those wrapping materials. Numerous references
contain disclosures suggesting various banded wrapping material
configurations. See, for example, U.S. Pat. No. 1,996,002 to
Seaman; U.S. Pat. No. 2,013,508 to Seaman; U.S. Pat. No. 4,452,259
to Norman et al.; U.S. Pat. No. 5,417,228 to Baldwin et al.; U.S.
Pat. No. 5,878,753 to Peterson et al., U.S. Pat. No. 5,878,754 to
Peterson et al.; and U.S. Pat. No. 6,198,537 to Bokelman et al.;
and PCT WO 02/37991. Methods for manufacturing banded-type wrapping
materials also have been proposed. See, for example, U.S. Pat. No.
4,739,775 to Hampl, Jr.; U.S. Pat. No. 5,474,095 to Allen et al.;
and PCT WO 02/44700 and PCT WO 02/055294. Some references further
describe banded papers having segments of paper, fibrous cellulosic
material or particulate material adhered to a paper web. See, for
example, U.S. Pat. No. 5,191,906 to Myracle, Jr.; U.S. Pat. No.
5,263,999 to Baldwin et al.; U.S. Pat. No. 5,417,228 to Baldwin et
al.; and U.S. Pat. No. 5,450,863 to Collins et al.; and U.S. Patent
Application Publication No. 2002/0092621 to Suzuki. In addition,
some references describe apparatuses and method for inspecting such
papers and wrapping materials, some of which may be capable of
operating in an automated and/or high speed process. See, for
example, U.S. Pat. No. 4,845,374 to White et al.; U.S. Pat. No.
5,966,218 to Bokelman et al.; U.S. Pat. No. 6,020,969 to Struckhoff
et al.; and U.S. Pat. No. 6,198,537 to Bokelman et al.; U.S. Patent
Application Publication Nos. 2003/0145869 and 2003/0150466 to Kitao
et al., and 2003/0197126 to Sato et al.; and U.S. patent
application Ser. Nos. 10/645,996, filed Aug. 22, 2003, and Ser. No.
10/665,066, filed Sep. 17, 2003.
[0006] Since certain properties are often required to provide the
desired burn characteristics and/or other characteristics of such
wrapping materials and since consistency between individual paper
wrappers for a particular product is also desired, it has been
desirable, if not necessary, to determine certain physical
properties or characteristics of wrapping materials for smoking
articles. For example, techniques for measuring the air
permeability or porosity of such wrapping papers, as well as the
diffusion of gases, such as carbon monoxide, through such wrapping
papers, have been developed. For example, the CORESTA method
(CORESTA Publication ISO/TC0126/SC I N159E (1986)) details a
procedure for measuring air flow through paper with a specified
pressure difference across the paper. This procedure may generally
provide accurate readings for large sample areas or relatively high
flow rates. However, this method may also be undesirably subject to
high relative errors and high variability for small sample areas
and low flow rates.
[0007] Further, for example, Drake et al. (D. G. Drake, D. S.
Riley, R. R. Baker and K. D. Kilbum, On a Cell to Measure Diffusion
Coefficients of Gases Through Cigarette Papers, Int. J. Heat and
Mass Transfer, 23 (1980) 127-134) describe a procedure for direct
measurement of paper diffusion coefficients. However, this
reference does not describe an apparatus suitable for measuring
small band areas of a sample. In addition, Durocher (U.S. Pat. No.
4,615,345 and other patents) describes an indirect and destructive
sample test producing results asserted to be proportional to paper
diffusion coefficients. However, such a method is undesirably
limited by destruction of the sample and the amount of time
required to perform the test.
[0008] Thus, there exists a need for an apparatus and method
capable of nondestructively measure certain physical properties or
characteristics of wrapping papers, such as those used for the
manufacture of smoking articles. Such an apparatus and method
should be capable of expeditiously determining the value of the
particular characteristic for the tested sample of the wrapping
paper and, in some instances, would desirably have the capability
of being applied in an automated and/or high speed process to
perform regular or random evaluations of the paper wrappers.
Further, such an apparatus and method should desirably be
nondestructive to the paper wrapper, applicable to a small area of
the paper wrapper (sample), cost and time effective, and capable of
being implemented in an environmentally friendly manner.
BRIEF SUMMARY OF THE INVENTION
[0009] The above and other needs are met by the present invention
which, in one embodiment, provides an apparatus adapted to measure
a property of a cigarette paper wrapper. Such an apparatus includes
a sampling device defining a first chamber portion and a
corresponding second chamber portion, wherein the first and second
chamber portions engage at and define a sampling area. The sampling
device is configured to receive the cigarette paper wrapper such
that the cigarette paper wrapper spans the sampling area and
separates the first chamber portion from the second chamber
portion. A first gas source is configured to supply a regulated
flow of a carrier gas to the first chamber portion, while a second
gas source is configured to supply a regulated flow of a detectable
gas to the second chamber portion. An analyzer device in
communication with the first chamber portion is configured to
receive a resultant gas flow, wherein the resultant gas flow
includes the carrier gas and any of the detectable gas entering the
first chamber portion through the cigarette paper wrapper. The
analyzer device is further configured to be capable of determining
an amount of the detectable gas in the resultant gas flow so as to
thereby determine a property of the cigarette paper wrapper, such
as the diffusion coefficient with respect to the detectable
gas.
[0010] Another advantageous aspect of the present invention
comprises a method of measuring a property of a cigarette paper
wrapper. First, a cigarette paper wrapper is received in a sampling
device defining a first chamber portion and a corresponding second
chamber portion, wherein the first and second chamber portions
engage at and define a sampling area. The sampling device is
further configured to receive the cigarette paper wrapper such that
the cigarette paper wrapper spans the sampling area and separates
the first chamber portion from the second chamber portion. A
regulated flow of a carrier gas is then supplied to the first
chamber portion, while a regulated flow of a detectable gas is
supplied to the second chamber portion. A resultant gas flow is
thereafter received at an analyzer device in communication with the
first chamber portion, wherein the resultant gas flow including the
carrier gas and any of the detectable gas entering the first
chamber portion through the cigarette paper wrapper. An amount of
the detectable gas in the resultant gas flow is then determined
with the analyzer device, from which a property of the cigarette
paper wrapper, such as the diffusion coefficient with respect to
the detectable gas, is determined.
[0011] Thus, embodiments of the present invention meet the
above-identified needs and provide distinct advantages as further
detailed herein.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0012] Having thus described the invention in general terms,
reference will now be made to the accompanying drawings, which are
not necessarily drawn to scale, and wherein:
[0013] FIG. 1 is a schematic of an apparatus adapted to measure a
property of a cigarette paper wrapper according to one embodiment
of the present invention.
[0014] FIG. 2 is a schematic plan view of a banded cigarette paper
wrapper advancing through an apparatus adapted to measure a
property of a cigarette paper wrapper according to one embodiment
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The present inventions now will be described more fully
hereinafter with reference to the accompanying drawings, in which
some, but not all embodiments of the invention are shown. Indeed,
these inventions may be embodied in many different forms and should
not be construed as limited to the embodiments set forth herein;
rather, these embodiments are provided so that this disclosure will
satisfy applicable legal requirements. Like numbers refer to like
elements throughout.
[0016] FIG. 1 schematically illustrates an apparatus, indicated
generally by the numeral 10, adapted to measure a property of a
cigarette paper wrapper according to one embodiment of the present
invention, wherein the apparatus 10 may be used, for example, to
evaluate various types of paper wrapping materials and treated
wrapping materials as disclosed in U.S. Patent Application
Publication No. 2003/0131860 to Ashcraft et al., which is
incorporated herein in its entirety by reference. Such an apparatus
10 comprises a sampling device 100 defining a first chamber portion
150 and a corresponding second chamber portion 200. The first and
second chamber portions 150, 200 are configured to be capable of
engaging about a sampling area 250, wherein the sampling area 250
is defined by one or more dimensions. The sampling device 100 is
further configured to receive a cigarette paper wrapper 50 between
the first and second chamber portions 150, 200. Preferably, the
sampling area 250 and/or the cigarette paper wrapper 50 are
dimensioned such that the cigarette paper wrapper 50 spans the
sampling area 250 and extends sufficiently beyond the sampling area
250 so as to be capable of being secured between the first and
second chamber portions 150, 200. For example, the first and second
chamber portions 150, 200 may be movable with respect to each other
so as to allow the cigarette paper wrapper 50 to be placed
therebetween. Such a cigarette paper wrapper 50 may vary
considerably in, for example, composition and characteristics, some
of which are described in, for instance, U.S. Patent Application
Publication No. 2003/0131860, also assigned to the assignee of the
present invention. Accordingly, U.S. Patent Application Publication
No. 2003/0131860 is incorporated herein in its entirety by
reference.
[0017] In a particularly advantageous embodiment, the engaging
faces of the first and second chamber portions 150, 200 are
configured to be brought together, with the cigarette paper wrapper
50 therebetween, so as to form a seal therewith. For example, the
engaging faces of the first and second chamber portions 150, 200
may be machined to respective flat surfaces or into any other
suitable complementary configuration. However, if necessary, each
of the first and second chamber portions 150, 200 may have, for
instance, a gasket 140 on the engaging faces thereof surrounding
the sampling area 250. Such a configuration is shown in FIG. 1, but
it will be understood that the gaskets 140 may not be necessary in
light of the particularly advantageous gasket-less embodiment
previously described. If gaskets 140 are used, the gaskets 140 form
a seal between the respective chamber portion and the cigarette
paper wrapper 50 when the cigarette paper wrapper 50 is placed
between the first and second chamber portions 150, 200 and the
first and second chamber portions 150, 200 are brought together. In
particularly advantageous instances, with or without the gaskets
140, the first and second chamber portions 150, 200 are configured
to form a substantially air-tight seal about the cigarette paper
wrapper 50. One skilled in the art will appreciate, however, that
many different configurations for sealing the cigarette paper
wrapper 50 between the first and second chamber portions 150, 200
may be possible, preferably without causing damage or deformity to
the cigarette paper wrapper 50, and that the configurations
presented herein are merely examples thereof. In any instance, the
cigarette paper wrapper 50 essentially separates the first chamber
portion 150 from the second chamber portion 200 when secured
therebetween.
[0018] Each of the first and second chamber portions 150, 200
further includes a respective gas inlet port 160, 210 and a
respective gas outlet port 170, 220. The gas inlet port 160 of the
first chamber portion 150 is connected a gas supply 180 of a
carrier gas. According to one advantageous embodiment of the
present invention, the carrier gas is substantially inert,
comprising, for example, nitrogen, helium, argon, or the like.
Further, the gas inlet port 210 of the second chamber portion 200
is connected to a gas supply 230 of a detectable gas. In one
advantageous embodiment, the detectable gas is detectable over the
carrier gas. In addition, the detectable gas is preferably
substantially harmless if released to atmosphere. As such, the
detectable gas may comprise, for example, carbon dioxide, oxygen,
or the like. Respective gas flow regulating devices such as, for
example, mass flow meters 190, 240, are disposed between the gas
supplies 180, 230 and the respective gas inlet ports 160, 210 for
regulating the flows of the gases. In advantageous instances, the
mass flow meters 190, 240 are adjustable such that substantially
equal mass flows of the respective gases are directed to flow into
the first and second chamber portions 150, 200 through the gas
inlet ports 160, 210 such that the pressures in the chamber
portions 150, 200 are also substantially equal. In this manner, the
gases do not provide a driving force in either direction through
the cigarette paper wrapper 50. In one advantageous embodiment, the
apparatus 10 is operated such that the pressures in the chamber
portions 150, 200 are close to atmospheric pressure.
[0019] The detectable gas leaving the second chamber portion 200
through the gas outlet port 220 may, in some instances, be vented
directly to atmosphere. However, in other instances, where the
detectable gas cannot be safely vented to atmosphere, one skilled
in the art will appreciate that the waste detectable gas may be
directed to a variety of devices for collecting, neutralizing,
and/or otherwise converting the detectable gas into a form suitable
for disposal. The gas outlet port 170 of the first chamber portion
150, however, is connected to an analyzer device 300. Such a
connection can be established, for example, through the use of a
sample loop (not shown) or other mechanism configured so as to
avoid elevating the pressure in the first chamber portion 150 over
the second chamber portion 200. The analyzer device 300 is thus
configured to receive a resultant gas flow from the first chamber
portion 150, wherein the resultant gas flow is comprised of the
carrier gas and any of the detectable gas that diffuses across the
cigarette paper wrapper 50 from the second chamber portion 200 into
the first chamber portion 150. As such, in one advantageous
embodiment, the analyzer device 300 is configured to be capable of
conducting at least one analysis to determine the amount of the
detectable gas in the resultant gas flow. Such an analysis can
indicate, for instance, the diffusivity or diffusion coefficient of
the cigarette paper wrapper 50 as described herein in further
detail. In some instances, under the conditions in the sampling
device 100, the diffusion of the detectable gas across the
cigarette paper wrapper 50 may require a certain amount of time to
reach an equilibrium, after which time the amount of the detectable
gas in the resultant gas flow remains substantially constant.
Accordingly, the analyzer device 300 may be configured, for
example, to make several measurements or analyses in order to
determine when such an equilibrium has been reached, or to perform
the measurement following a certain elapsed time from the start of
the test for the particular cigarette paper wrapper 50. For
instance, the analyzer device 300 may be configured to perform the
necessary measurement at between about 3 seconds and about 10
seconds after the test process is initiated.
[0020] According to one advantageous aspect of the present
invention, the diffusivity of the cigarette paper wrapper 50 can be
determined according to the following methodology. More
particularly, a sample of a cigarette paper wrapper 50 is first
placed between the first and second chamber portions 150, 200 so as
to span the sampling area 250. Once the wrapper 50 is secured
between the chamber portions 150, 200, a steady stream of a
substantially inert carrier gas, such as N.sub.2, is fed into the
first chamber portion 150 through the gas inlet port 160 thereof,
while a steady stream of a detectable gas, such as CO.sub.2, is fed
into the second chamber portion 200 through the gas inlet port 210
thereof. Since cigarette paper wrapper 50 is at least partially
porous, some CO.sub.2 detectable gas will tend to migrate from the
second chamber portion 200, through the wrapper 50, and into the
N.sub.2 carrier gas stream (and likewise, some of the N.sub.2
carrier gas will tend to migrate through the wrapper 50 and into
the CO.sub.2 detectable gas stream). The rate at which the
detectable gas migration occurs is related to, for example, the
diffusion coefficient of the wrapper (D.sub.p), the binary
diffusion coefficient of CO.sub.2 into N.sub.2 (D.sub.g=0.171
cm.sup.2/s), the temperature (T), the differential pressure
(.DELTA.P), and the gas concentration differential between the
first and second chamber portions 150, 200. The diffusion
coefficient D.sub.p of the wrapper 50 can be subsequently
calculated, for instance, from the concentration of the detectable
gas in the resultant gas flow (the measured outlet gas
concentration (CO.sub.out)) and the aforementioned parameters.
[0021] One skilled in the art will also appreciate that the
concentration of the respective gas in each chamber portion 150,
200 may change along the length of the sampling area 250
(.delta.C/.delta.x) depending on the amount of the respective gas
migrating across the wrapper 50. Likewise the concentration of the
respective gas will vary over the depth of the respective chamber
portions 150, 200 (.delta.C/.delta.z), corresponding to a distance
away from the sample of the wrapper 50. Thus, taking these various
factors into consideration, the resultant system of partial
differential equations relating the concentration of the detectable
gas in the resultant gas flow (% CO.sub.2) in the first chamber
portion 150 to the diffusion coefficient DP of the cigarette paper
wrapper 50 (as discussed in D. G. Drake, D. S. Riley, R. R. Baker
and K. D. Kilburn, On a Cell to Measure Diffusion Coefficients of
Gases Through Cigarette Papers, Int. J. Heat and Mass Transfer, 23
(1980) 127-134, the contents of which are incorporated herein by
reference) may have the general form: 1 m = 2 2 n = 1 .infin. 1 n 2
[ n 2 + 2 + ] - 6 n 2 x Eqn . 1
[0022] where .mu..sub.n are the positive roots of
.mu. tan .mu.=.alpha. Eqn. 2
[0023] Further:
.theta..sub.m=2C.sub.out/C.sub.CO2-1 Eqn. 3
.chi.=bD.sub.gx/6Ve Eqn. 4
.alpha.=2eD.sub.p/tD.sub.g Eqn. 5
[0024] where:
[0025] C.sub.CO2=input CO.sub.2 concentration=100%;
[0026] b=chamber portion width;
[0027] x=chamber portion length;
[0028] V=volumetric flow rate;
[0029] e=chamber portion depth; and
[0030] t=wrapper thickness.
[0031] The solution is subsequently determined, for example, by a
numerical iteration procedure, as follows:
[0032] 1) Determine an initial estimate for D.sub.p;
[0033] 2) Calculate .alpha. using Eqn. 5;
[0034] 3) Determine the first ten positive values for .mu. that
satisfy Eqn. 2;
[0035] 4) Calculate C.sub.out as predicted by Eqn. 1;
[0036] 5) Compare to calculated C.sub.out to C.sub.out actually
measured; and
[0037] 6) Increment D.sub.p and repeat steps 2-5 until calculated
C.sub.out is within 0.01% of C.sub.out actually measured.
[0038] D.sub.p, expressed in units of, for example, cm.sup.2/s,
describes a rate of migration through a material and is independent
of the material's geometry. Further, a cigarette burn rate is at
least partly governed by the amount of oxygen that diffuses from
ambient through the cigarette paper wrapper 50 and into the fire
coal. Accordingly, another relevant measurement may be a diffusive
flux (D*) across the cigarette paper wrapper 50, expressed in terms
of volume of gas per unit area per unit time (cm.sup.3/cm.sup.2/s
or cm/s). D* may also be expressed as the ratio of DP and the
wrapper thickness t (D*=D.sub.p/t).
[0039] In order to simplify these calculations for routine use, D*
and CO.sub.out as calculated can be related with the aforementioned
procedure at standard ambient conditions (725 torr, 299.degree. K.)
by, for example, a fourth degree polynomial regression (at least
partially dependent on the dimensions of the chamber) having an
applicable equation as follows:
D*.sub.s=.lambda..sub.4C.sub.out.sup.4.lambda..sub.3C.sub.out.sup.3+.lambd-
a..sub.2C.sub.out.sup.2.lambda..sub.1C.sub.out Eqn. 6
[0040] wherein this equation is applicable to a chamber having
particular dimensions for chamber width (b=0.4 cm), chamber length
(x=2.0 cm), and chamber depth (d=0.175 cm), and
[0041] where:
[0042] .lambda..sub.4=1.530E-04;
[0043] .lambda..sub.3=-887.513E-04;
[0044] .lambda..sub.2=8.624E-03; and
[0045] .lambda..sub.11=1.184E-01.
[0046] D*.sub.s thus denotes the diffusion coefficient at the
standard environmental conditions and for the specific chamber
dimensions described above. However, in instances where a
controlled mass flow is fed into the respective chamber portions
150, 200, the volumetric flow and resultant D* must be corrected
for temperature and barometric pressure, as follows: 2 D * = D s *
.times. 725 P a .times. T a 299 Eqn . 7
[0047] where:
[0048] P.sub.a=ambient pressure; and
[0049] T.sub.a=ambient temperature.
[0050] The flow rates of both the carrier gas and the detectable
gas may be readily determined from the respective mass flow meters
190, 240. As such, the diffusion coefficient D.sub.p of the
cigarette paper wrapper 50 may be determined using the described
apparatus 10, as detailed, according to embodiments of the present
invention.
[0051] In some instances, as shown in FIG. 2, the cigarette paper
wrapper 50 may be provided as a contiguous roll 350 of cigarette
paper wrappers 50, wherein, in some instances, each cigarette paper
wrapper 50 may comprise two contiguous bands 60, 70 though, in some
instances, each cigarette paper wrapper 50 may comprise more than
two bands. According to other aspects of the present invention, the
bands 60, 70 can have different values of a common property, as
will be appreciated by one skilled in the art. For example, one
band may have a greater diffusion coefficient than the other band.
When arranged along the roll 350, the bands 60, 70 are regularly
repeating. As such, in some instances, the apparatus 10 may be
configured to selectively perform a measurement of either or both
bands 60, 70 at selected points along the roll 350. In such
instances, the apparatus 10 further includes an advancement device
400 for advancing the cigarette paper wrappers 50 from the roll 350
through the sampling device 100.
[0052] One skilled in the art will further appreciate that
embodiments of the apparatus 10, applicable to a roll 350 of
cigarette paper wrappers 50, may be configured in many different
manners. For example, the apparatus 10 may be configured to perform
a measurement of each and every band 60, 70 along the roll 350.
However, such a configuration may not be practical in a
manufacturing process. Accordingly, the apparatus 10 may be
configured so as to selectively perform a measurement at various
intervals along the roll 350. For example, the apparatus 10 may be
configured to measure each tenth occurrence of the first band 60
and/or the second band 70. In such instances, the apparatus 10 may
further include a sensor 450 operably engaged with the advancement
device 400 and capable of directing the advancement device 400 to
stop the advancement of the cigarette paper wrappers 50 on the roll
350 when a certain point on the roll 350 is reached such that a
particular band lies within the sampling device 100. More
particularly, the sensor 450 may be configured to analyze the roll
350 so as to direct the advancement device 400 to stop the
advancement of the cigarette paper wrappers 50 when only one of the
bands 60, 70 is spanning the sampling area 250 within the gaskets
140. Such a sensor 450 may comprise an optical sensor, though one
skilled in the art will appreciate that many different types of
sensors and/or other mechanisms may be implemented to accomplish
the selective stopping of the advancement of the roll 350 as
described herein. For example, a registration and inspection system
(not shown) may be implemented, wherein such a system may include,
for instance, a detection apparatus utilizing a spectroscopic
(non-optical) system such as a non-contact ultrasonic transmission
system or a near infrared (NIR) absorption system.
[0053] In addition, in other instances, the apparatus 10 may also
include a sensor 500 operably engaged with the analyzer device 300,
wherein such a sensor 500 may be configured to determine when the
advancement of the roll 350 has stopped and when the sampling
device 100 is prepared for a measurement with only one of the bands
60, 70 spanning the sampling area 250. Upon sensing the necessary
conditions, the sensor 500 may actuate the gas supplies 180, 230 to
start the gas flows, may actuate the mass flow sensors 190, 240 to
appropriately regulate the gas flows, and then actuate the analyzer
device 300 to perform the measurement at the appropriate moment.
However, one skilled in the art will appreciate that several
sensors or other mechanisms may be implemented to perform such
tasks.
[0054] Many modifications and other embodiments of the inventions
set forth herein will come to mind to one skilled in the art to
which these inventions pertain having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. For example, embodiments of the apparatus 10 as described
herein may be controlled by, incorporate, or otherwise include a
computer device (not shown) such as a computer, controller, or the
like capable of controlling any or all of the described components
and/or functions of the apparatus 10. In addition, where such a
computer device is included, one skilled in that art will
appreciate that associated methods and computer software program
products will be within the spirit and scope of the present
invention. Further, one skilled in the art will appreciate that the
described apparatus may be other wise configured or include
additional components so as to be capable of determining other
properties of the cigarette paper wrapper 50, such as, for example,
a tensile strength or porosity thereof (that may be related to the
diffusion coefficient D.sub.p), other than those properties
described in detail herein. Therefore, it is to be understood that
the inventions are not to be limited to the specific embodiments
disclosed and that modifications and other embodiments are intended
to be included within the scope of the appended claims. Although
specific terms are employed herein, they are used in a generic and
descriptive sense only and not for purposes of limitation.
* * * * *