U.S. patent application number 13/896068 was filed with the patent office on 2017-05-11 for cigarette wrapper with novel pattern.
This patent application is currently assigned to Altria Client Services Inc.. The applicant listed for this patent is Altria Client Services Inc.. Invention is credited to Marc Rose, Timothy S. Sherwood, Robert N. Smith.
Application Number | 20170127718 13/896068 |
Document ID | / |
Family ID | 49580272 |
Filed Date | 2017-05-11 |
United States Patent
Application |
20170127718 |
Kind Code |
A9 |
Rose; Marc ; et al. |
May 11, 2017 |
CIGARETTE WRAPPER WITH NOVEL PATTERN
Abstract
A wrapper for a smoking article has a base web and a plurality
of elements each having at least a pair of patch areas where
diffusivity is in the range of 0 to about 0.2 cm/sec. Patches of
adjacent elements are circumferentially offset from one another
along the axis of a smoking article. The add-on material can be
applied by gravure printing in a single pass in a chevron pattern
such that an apex of the element is co-linear with substantially
symmetrically spaced points on a trailing, outer edge of an
adjacent element. Testing elements may be simultaneously printed
with the add-on material to monitor diffusivity and/or presence of
add-on material.
Inventors: |
Rose; Marc; (Mechanicsville,
VA) ; Sherwood; Timothy S.; (Midlothian, VA) ;
Smith; Robert N.; (Glen Allen, VA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Altria Client Services Inc. |
Richmond |
VA |
US |
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Assignee: |
Altria Client Services Inc.
Richmond
VA
|
Prior
Publication: |
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Document Identifier |
Publication Date |
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US 20130306088 A1 |
November 21, 2013 |
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Family ID: |
49580272 |
Appl. No.: |
13/896068 |
Filed: |
May 16, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13324747 |
Dec 13, 2011 |
9302522 |
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13896068 |
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61647898 |
May 16, 2012 |
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61422525 |
Dec 13, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A24D 1/025 20130101 |
International
Class: |
A24D 1/02 20060101
A24D001/02 |
Claims
1. A wrapper for a smoking article including a tobacco rod, the
wrapper comprising: a base web having a longitudinal direction and
a transverse direction; and an add-on material applied to the base
web according to a pattern comprising a plurality of generally
transverse rows of patch elements, the rows being spaced from one
another in the longitudinal direction of the base web, each row
including a plurality of transversely spaced apart patch elements,
each patch element having a diffusivity in the range of 0 to about
0.2 cm/sec, the add-on material comprising starch and an
anti-wrinkling agent, and said add-on material having been applied
to the base web as an aqueous starch solution; the add-on material
being in a condition of having been applied to the base web in a
single pass application while being maintained by thermal
conditioning at a desired viscosity and film-forming capacity; the
rows being in a condition of having been applied to the base web in
a chevron form; and the rows being mutually off-set from one
another according to a repeated, predetermined pattern, with a
predetermined number of rows establishing a row set, the row sets
establishing a snuffer region at a location along the tobacco rod
comprising the wrapper.
2. The wrapper of claim 1, wherein the chevron form extends in a
transverse direction of the base web and points in the longitudinal
direction.
3. The wrapper of claim 2, wherein the chevron form includes an
apex and an angle at the apex, the angle being in the range of
about 0.5.degree. to about 5.degree..
4. The wrapper of claim 2, wherein the patches of one patch row are
offset from patches of a second patch row in the transverse
direction of the base web.
5. The wrapper of claim 2, wherein each patch extends in the range
of about 7 to about 8 mm in the transverse direction, and extends
in the range of about 6 to about 9 mm in the longitudinal
direction.
6. The wrapper of claim 5, wherein each patch extends about 7.5 mm
in the transverse direction, and extends in the range of about 7 to
about 8 mm in the longitudinal direction.
7. The wrapper of claim 1, wherein the add-on material includes
calcium carbonate.
8. The wrapper paper of claim 1, wherein the anti-wrinkling agent
is selected from the group consisting of propylene glycol; 1,2
propylene glycol; and glycerin.
9. The wrapper paper of claim 1, wherein the base web has a
permeability of greater than about 20 CORESTA.
10. The wrapper paper of claim 1, wherein the base web has a
permeability of less than about 100 CORESTA.
11. The wrapper paper of claim 1, wherein said thermal conditioning
comprises maintaining said add-on material in a solution at a
temperature ranging from about 120.degree. F. to about 150.degree.
F. until applied.
12. The wrapper of claim 11, wherein said desired viscosity ranges
from about 16.5 seconds to about 19.5 seconds as measured by a Zahn
#2 cup at 120.degree. F. at time of application.
13. The wrapper of claim 14, wherein said desired film-forming
capacity comprises release of at least one of amylopectin and
amylose from a starch in said solution.
14. A smoking article comprising: a rod of smokeable material, said
rod comprising a filler and a wrapper, the rod having a
circumferential direction and an axial direction; the wrapper
further including: a base web; a plurality of patch elements having
at least two patches formed of add-on material, the patches being
spaced from one another in the circumferential direction, the patch
elements being spaced from one another in the axial direction, and
the patches having a diffusivity in the range of 0.0 to about 0.2
cm/sec.
15. The smoking article of claim 14, wherein at least four patch
elements are provided on the rod of smokeable material.
16. The smoking article of claim 14, wherein the patches of each
patch element are circumferentially offset from the patches of each
adjacent patch element.
17. The smoking article of claim 16, wherein the circumferential
offset is in the range of about 40.degree. to about 90.degree.,
measured in the circumferential direction about an axis of the
smokeable rod.
18. The smoking article of claim 17, wherein the circumferential
offset is about 45.degree..
19. The smoking article of claim 14, wherein the patches are
generally quadrilateral.
20. The smoking article of claim 14, wherein the patches are
generally rectangular.
21. The smoking article of claim 14, wherein the each patch extends
in the range of about 7 to about 8 mm in the circumferential
direction, and extends in the range of about 6 to about 9 mm in the
axial direction.
22. The smoking article of claim 14, wherein the add-on material
comprises starch, calcium carbonate, and an anti-wrinkling
agent.
23. The smoking article of claim 22, wherein the add-on material is
aqueous when applied.
24. The smoking article of claim 22, wherein the anti-wrinkling
agent is selected from the group consisting of propylene glycol;
1,2 propylene glycol; and glycerin.
25. The smoking article of claim 14, wherein the base web has a
permeability of greater than about 20 CORESTA.
26. The smoking article of claim 14, wherein the base web has a
permeability of less than about 100 CORESTA.
27. The smoking article of claim 14, having an IP performance of
less than about 25%; and having an SE performance less than about
50%.
28. A smoking article comprising a tobacco rod, said tobacco rod
comprising a wrapper, said wrapper comprising a plurality of patch
elements arranged in circumferentially extending, longitudinally
spaced-apart, mutually offset rows, said patch elements of such
number, size, and diffusivity value that said smoking article
exhibits an IP performance of less than about 15%; and exhibits an
average SE performance less than about 35%.
29. A method of achieving ignition propensity performance in a
smoking article together with statistically fewer
self-extinguishments in such smoking articles, comprising:
establishing on a wrapper of said smoking article a plurality of
patch elements arranged in circumferentially extending,
longitudinally spaced-apart, mutually offset rows; said
establishing step including establishing said patch elements at
predetermined size and diffusivity value such that said smoking
article exhibits an IP performance of less than about 15%; and
exhibits an average SE performance less than about 35%.
30. The method of claim 29, wherein said diffusivity value is
established in the range of 0 to about 0.2 cm/sec.
31. The method of claim 29 further including forming the patches by
single-pass printing of an aqueous solution containing starch,
calcium carbonate, and an anti-wrinkling agent.
32. The method of claim 31, wherein said establishing further
comprises applying the rows of patch elements to a base web
according to a chevron form.
33. A process of making wrapper for a smoking article comprising:
applying an add-on material on a base web in the form of a
plurality of patch elements; controlling diffusivity values in the
patch elements to lie in the range of 0 to about 0.2 cm/sec using
an aqueous solution of starch, calcium carbonate, and an
anti-wrinkling agent.
34. The process of claim 33, further including selecting the
anti-wrinkling agent from the group consisting of propylene glycol;
1,2 propylene glycol; and glycerin.
35. The process of claim 33 further including slitting the base web
to form bobbins.
36. The process of claim 33, wherein the elements of patches are
applied to the base web in a chevron pattern.
37. The process of claim 36, wherein the patch elements are applied
to the base web in a chevron pattern such that an apex of a lagging
chevron is essentially transverse of an outer edge portion of a
leading chevron.
38. The process of claim 36, wherein the chevron pattern has an
angle with respect to the transverse direction of the web, which
angle lies in the range of about 0.5.degree. to about
5.degree..
39. A wrapper substantially free of creases and frayed edges, the
wrapper in a condition of having been formed by: printing an add-on
material on a base web in the form of a plurality of elements of
patches; and controlling diffusivity in the patches to lie in the
range of 0 to about 0.2 cm/sec using an aqueous solution of starch,
calcium carbonate, and an anti-wrinkling agent, the aqueous
solution in a condition of having been maintained at a temperature
ranging from about 120.degree. F. to about 140.degree. F. prior to
application.
40. A method of conducting quality control in a manufacture of a
wrapper comprising rows of occlusive elements, said method
comprising: printing a first pattern of said rows of occlusive
elements in a first lane along a base web with an add-on material
and a gravure roller having a cell geometry; and concurrently
printing a second pattern of test elements in a second lane along
said base web with said add-on material and said cell geometry;
conducting on portions of said second pattern testing for
diffusivity; and optionally testing for a presence of said first
pattern; whereby at least one of a diffusivity value and a presence
of said first pattern is monitored.
41. The method of claim 40 wherein each test element has sufficient
size and/or geometry to facilitate measurement of diffusivity.
Description
WORKING ENVIRONMENT
Ignition Propensity ("IP")
[0001] A measure of the tendency of a smoking article to cause
ignition when left placed upon a substrate is the Ignition
Propensity value. An Ignition Propensity value, or IP value, of a
smoking article should preferably be no greater than about 25%.
More preferably, the IP value should be no greater than about 20%;
and even more preferably no greater than about 10%.
[0002] Ignition Propensity or IP is a standard test conducted as
set forth in ASTM E 2187-04, "Standard Test Method for Measuring
the Ignition Strength of Smoking articles", which is incorporated
herein in its entirety by this reference thereto. Ignition
propensity measures the probability that a smoking article, when
smoldering and placed on a substrate, will generate sufficient heat
to maintain smoldering of the tobacco rod. Low values for IP are
desirable as such values correlate with a reduced likelihood that a
smoldering smoking article, when inadvertently left unattended upon
a substrate, will cause combustion in the substrate.
Self Extinguishment ("SE")
[0003] Smoking articles exhibiting reduced IP values typically also
tend to self-extinguish between puffs during smoldering, which is
contrary to adult consumer expectations. Adult consumers do not
like having to re-light a cigarette during their smoking
experience.
[0004] A measure of the tendency for a smoking article to
self-extinguish during free burn has been developed and is known as
the Self-Extinguishment value. The Self-Extinguishment value or SE
value has been found to be a useful indicia of the likelihood of a
smoking article to self-extinguish between puffs during smoking.
The Self-Extinguishment Average value for a smoking article should
preferably be no greater than about 80% and/or the
Self-Extinguishment at 0.degree. value (0.degree. indicating that
the cigarette is smoldering in horizontal orientation) should be no
greater than about 50%, and more preferably no greater than about
25%.
[0005] Self-Extinguishment or SE herein is a reference to
smoldering characteristics of a smoking article under free burn
conditions (away from any substrate). To evaluate SE, a laboratory
test is conducted at a temperature of 23.degree. C..+-.3.degree. C.
and relative humidity of 55%.+-.5%, both of which should be
monitored by a recording hygrothermograph. Exhaust hood(s) remove
combustion products formed during testing. Prior to testing,
smoking articles to be tested are conditioned at 55%.+-.5% relative
humidity and 23.degree. C..+-.3.degree. C. for at least 24 hours.
To facilitate conditioning, the smoking articles are placed in
glass beakers to assure free air access.
[0006] SE testing takes place within an enclosure or test box. A
single port smoking machine or an electric lighter is used to
ignite the smoking articles for the test. During testing, an
apparatus or "angle holder" holds the smoking articles to be tested
by holding an end at angles of 0.degree. (horizontal), 45.degree.,
and/or 90.degree. (vertical). Preferably, twenty (20) smoking
articles are tested at each of the 0.degree., 45.degree., and
90.degree. positions. If more than one apparatus is used, the
apparatuses are preferably positioned such that the smoking
articles face away from each other to avoid cross interference. If
a smoking article goes out before the front line of the smoldering
coal reaches the tipping paper, the outcome is scored as
"self-extinguishment"; on the other hand, if the smoking article
continues smoldering until the front line of the smoldering coal
reaches the tipping paper, then the outcome is scored as
"non-extinguishment". Thus, for example, an SE value of 95%
indicates that 95% of the smoking articles tested exhibited
self-extinguishment under the free burn conditions; while an SE
value of 20% indicates that only 20% of the smoking articles tested
exhibited self-extinguishment under such free burn conditions.
[0007] The SE value may be referred to in terms of
"Self-Extinguishment at 0.degree. value", "Self-Extinguishment at
45.degree. value", or "Self-Extinguishment at 90.degree. value",
each of which refers to the value of SE at the specified tested
angle. In addition, the SE value may be referred to in terms of
"Self-Extinguishment Average value", which refers to an average of
the three angular positions: namely, an average of (i) the
"Self-Extinguishment at 0.degree. value" (level, or horizontal
orientation), (ii) the "Self-Extinguishment at 45.degree. value",
and (iii) the "Self-Extinguishment at 90.degree. value" (vertical
orientation). A reference to "Self-Extinguishment value" or "SE
value" does not distinguish between SE at 0.degree., SE at
45.degree., SE at 90.degree., or SE average values and may refer to
any one of them.
[0008] As noted above, it is desirable to achieve IP performance
with a patterned paper that meets and exceeds governmental
requirements. As previously noted, achievement of a desired IP
performance often adversely impacts the SE performance of the
smoking article. Stated differently, while an IP performance of a
smoking article may meet or exceed the governmental requirement
(i.e., it has a 0% IP value), that level of IP performance
typically results in a smoking article that will self-extinguish
when the cigarette smolders away from any substrate (i.e., it has
an SE value of 100%). Improvement of SE performance while
maintaining requisite IP performance constitutes a highly desirable
feature for cigarette wrappers and smoking articles constructed
from them. Applicants have discovered arrangements of the patch
elements on wrapper that provide such improved SE performance while
maintaining the desired or requisite IP performance.
SUMMARY
[0009] In accordance with this disclosure, an improved cigarette
wrapper and smoking article using that wrapper has remarkably low
IP and SE values, which values satisfy various governmental
regulations and requirements for smoking articles. The improved
wrapper exhibits circumferential patch elements of add-on material,
where the add-on material is applied in substantially rectangular
shapes or patches in a single printing application. The patches
have a width measured in the longitudinal direction of the wrapper,
which width preferably lies in the range of about 5 to about 10 mm,
more preferably in the range of about 6 to about 9 mm. The patches
preferably also have a circumferential dimension which lies in the
range of about 6 to about 10 mm, more preferably about 7 to about 9
mm, such that the patches of a row are circumferentially spaced
from one another by a distance of about 5 mm.
[0010] The patches are preferably applied to a base web using an
aqueous starch solution containing an anti-wrinkling agent and
calcium carbonate. Preferably, the anti-wrinkling agent comprises
propylene glycol. Particularly preferred composition of the aqueous
starch solution are explained more fully below. Nevertheless, when
dried, the add-on material in the patches exhibits a diffusivity in
the range of 0 to about 0.2 cm/sec, and preferably in the range of
0 to about 0.1 cm/sec.
[0011] Preferably, the add-on material is applied to the base web
in a single step, gravure printing operation, which operation
includes maintenance of the add-on material at temperatures
sufficient to avoid degradation of the aqueous starch solution.
Single pass operations with measures to abate wrinkling of the base
web have been avoided to present difficult alignment and
registration issues encountered in high speed multi-pass
operations. Practice of the teachings herein provides a wrapper
having enhanced consistency and more predictable ignition
propensity (IP) and SE performances.
[0012] Preferably, the printed pattern on the base web includes one
or more longitudinally extending lanes of spaced apart rows of
patches of a nominal add-on rate, together with one or more lanes
of test marks adjacent to the lane(s) of patches. Preferably, the
test marks are applied to the base web at the same add-on rate as
for the patch elements and may comprise a plurality of spaced-apart
solid bands of add-on material or other geometric form of
sufficient size and/or geometry to facilitate measurement of
diffusivity for purposes of quality control. As spaced-apart solid
bands, the test marks also can be used to optically inspect the
base web during printing operations to confirm presence of desired
print patterns along the base web during its conversion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Many objects and advantages of the present disclosure will
be apparent to those skilled in the art when this specification is
read in conjunction with the accompanying drawings, wherein like
reference numerals are applied to like patch elements and
wherein:
[0014] FIG. 1 is a side elevation of a smoking article according to
the disclosure, where the patch elements are shown in solid lines
for illustrative purposes.
[0015] FIG. 2 is a plan view of a portion of a base web with patch
elements applied thereto.
[0016] FIG. 3 is a process flow diagram of a process for making and
applying an aqueous starch solution to a base web.
[0017] FIG. 4 is a side elevation of a smoking article according to
the disclosure, placed against a substrate.
[0018] FIG. 5 is a side elevation of smoking article according to
the disclosure, similar to FIG. 4, but rotated about 45.degree.
about the axis of the smoking article.
[0019] FIG. 6 is a side elevation of a smoking article according to
the disclosure, similar to FIG. 4, but rotated about 90.degree.
about the axis of the smoking article.
[0020] FIG. 7 is a cross-sectional view taken along the line 7-7 of
FIG. 4.
[0021] FIG. 8 is a cross-sectional view taken along the line 8-8 of
FIG. 4.
[0022] FIG. 9 is a cross-sectional view taken along the line 9-9 of
FIG. 4.
[0023] FIG. 10 is a transverse cross-sectional view of the smoking
article of FIG. 1 with the patches oriented for optimal ignition
propensity.
[0024] FIG. 11 is a transverse cross-sectional view of the smoking
article of FIG. 1, similar to FIG. 10, but showing a free-burn
condition.
[0025] FIG. 12 is a schematic view of a gravure printing
system.
[0026] FIG. 13 is schematic perspective view of a gravure roller
according to the disclosure.
[0027] FIG. 14 is a plan view of a base web with representation in
outline of areas where patch elements are applied.
[0028] FIG. 15 is a reduced scale view of a base web which includes
primary lanes comprising spaced-apart transverse rows of printed
patch elements and supplementary lanes comprising spaced-apart
transverse test marks in the form of solid banded regions.
DETAILED DESCRIPTION
[0029] Referring to FIG. 1, in a preferred embodiment, a smoking
article 120 (e.g., a cigarette) preferably comprises a tobacco rod
122 and optionally a filter 132 attached to the tobacco rod 122
with a tipping paper 193. The tobacco rod 122 comprises a column of
smokeable material (e.g., tobacco cut filler) and a wrapper 123
disposed about the column of smokeable material. Preferably, the
wrapper 123 includes a plurality of spaced apart, circumferential
rows 131a, b, c. d, each row comprising one or more patch elements
(or "patches") 126 of add-on material. The rows 131a, b, c, d and
their respective patch elements 126 are configured to obtain
extinguishment when a smoldering smoking article 120 is left
unattended on a substrate. Preferably, the respective patch
elements 126 of adjacent rows 131a, b, c, d are circumferentially
off-set from one another, more preferably, each of the second,
third, and fourth rows 131b, c, d, respectively are increasingly
off-set from the first row 131a, and together all four rows 131a,
b, c, d define a set of rows 139 (or row set 139). Referring now
also to FIG. 2, preferably, row sets 139 are uniformly repeated in
the printing of patch elements 126 on the base web 140. It is
envisioned that the number of rows 131 within a row set 139 could
be other than four (e.g., two, three, five or more), but four is
preferred particularly when a row 131 nominally comprises only two
patch elements.
[0030] Preferably, each patch (or patch element) 126 is rectangular
and is formed of an add-on solution which is aqueous and applied in
a single pass, gravure printing operation, which operation includes
maintenance of the add-on material at temperatures sufficient to
avoid degradation of the aqueous starch solution (see FIG. 3).
Single pass operations with measure to abate wrinkling of the base
web have been found to promote precise printing execution and avoid
misalignment or mis-registration issues during high speed
multi-pass printing operations. The preferred measures to abate
wrinkling include provision of an anti-wrinkling agent in an
aqueous starch add-on solution, which preferably also includes
calcium carbonate. Another technique to further abate wrinkling
(and creasing of cigarette wrapper) is to use a chevron printing
pattern for application of the rows 131 of patches 126 (instead of
straight lines without angularity), such as described in the
teachings which follow with reference to FIGS. 13-14.
[0031] Preferably, the material is applied at a rate sufficient to
achieve a diffusivity value of about 0 to about 0.2 cm/sec,
preferably 0 to about 0.1 cm/sec.
[0032] Referring now to FIG. 15, preferably, the printed pattern
806 of the base web 140 includes one or more longitudinally
extending lanes 810, 810' of spaced apart rows 131, 131' of patches
126 of a nominal add-on rate together with one or more supplemental
lanes 812, 812', 812'' of spaced apart, test marks 814, 814', 814''
adjacent to the lane(s) 810, 810' of patches 126. Preferably, the
test marks 814 are applied to the base web 140 at essentially the
same add-on rate (i.e., same solution, same engraving depth/cell
dimensions) as for the patch elements 126 and may comprise a
plurality of spaced-apart solid bands of add-on material or other
geometric form of sufficient size and/or geometry to facilitate
measurement of diffusivity for purposes of quality control.
[0033] In a preferred embodiment, the clamp mechanism of a
diffusivity tester encloses a rectangular area of base web of
approximately 4 mm by 15 mm. Accordingly, the test marks 810, 810'
are sized greater than the enclosed area of the clamp. In this
embodiment, the reference marks 810, 810' are sized approximately
5-6 mm wide and extend transversely by at least several inches. The
latter could be shortened.
[0034] The reference or test marks 810, 810' are configured to make
possible testing for diffusivity, whereas the patch elements 126
themselves are not so configured. The ability to measure the
diffusivity values in regions bearing the applied add-on material
reduces the need to make test cigarettes and to conduct ignition
propensity tests of smoldering cigarettes. Instead, the diffusivity
of the test marks 810, 810' is measured to confirm or deny by
correlation that the patch elements 126 in adjacent portions of the
base web are at the desired level of diffusivity and therefore
possess the desired level of IP performance. Being able to monitor
diffusivity values avoids the waste and cost associated with
preparing cigarettes and actually conducting ignition propensity
tests. As spaced-apart solid bands, the test marks can also be used
to optically inspect the base web during printing operations to
confirm presence of desired print patterns along the base web
during its conversion. To that end, one lane may be used to test
for presence of the desired print patterns, while another lane (of
test elements) may be used to test for diffusivity values. The test
protocol described herein is applicable to various patterns of
occlusive elements formed of add-on material, including without
limitation rows of occlusive elements comprising longitudinally
spaced-apart, transverse bands, patches and various patterns of
occlusive elements such as shown and described in U.S. published
application no. 2011/0297736, incorporated herein by reference in
its entirety. Suitable optical inspection techniques for
determining the presence of occlusive elements may include those
described in U.S. Pat. No. 6,198,537, which is incorporated herein
by reference in its entirety. Other inspection techniques could be
employed, including those which utilize wavelengths other than
visible.
[0035] All of the above-mentioned teachings and the further details
which follow contribute to a wrapper 123 which can provide enhanced
and more balanced IP performance and SE performance in smoking
articles constructed therefrom. Additionally, with the abatement of
wrinkling and single-pass operation, the patches 126 can be
precisely and more uniformly printed at commercially acceptable
printing speeds, which can be monitored during their construction
to assure acceptable levels of quality control. Further details of
the preferred embodiments are provided in the description which
follows.
DEFINITIONS
[0036] As used herein, the phrase "leading edge" refers to the edge
146 (see FIG. 1) of a patch element 126 that is closest to an
approaching coal during smoldering of a smoking article 120 whose
wrapper 123 contains the patch element 126, while the phrase
"trailing edge" refers to the edge 148 of a patch element 126 that
is farthest from an approaching coal during smoldering of a smoking
article 120 whose wrapper 123 contains the patch element 126.
[0037] With reference to FIG. 1, for purposes of this disclosure,
"band spacing" or "row spacing" refers to the distance 137 between
the trailing edge 148 of patch element 126 in a row 131 and the
nearest leading edge 146 of a patch element 126 of an adjacent row
131.
[0038] An "anti-wrinkling agent" is a material which abates the
tendency of an aqueous starch solution to shrink a base web upon
its application and drying. A suitable anti-wrinkling agent may be
selected from the group consisting of 1,2 propylene glycol,
propylene glycol, and glycerin. Other anti-wrinkling agents can be
used in addition to, or in lieu of the preferred materials. For
example, other suitable anti-wrinkling agents include polyols,
including without limitation, glycerol, polyethylene glycol,
glucose, sucrose, isomalt, maltilol, sorbitol, xylitol, and other
agents exhibiting comparable functionalities.
[0039] For purposes of this disclosure, "layer" refers to a unitary
quantity of add-on material applied to a base web from which a
wrapper is fabricated. A patch element 126 may be fashioned from
one or more layers that may be superimposed on one another; however
experience with multi-pass applications has shown a tendency of the
base web 140 to wrinkle upon application of an aqueous solution,
which confounds proper alignment and registration between
applications of the patch pattern, which caused consistency and
predictability in a wrapper's IP performance to suffer.
Accordingly, it is preferred to apply patch elements 126 in a
single-pass gravure operation, and further preferred to include
with the single-pass operations measures which abate wrinkling of
the base web 140.
[0040] For purposes of this disclosure, "longitudinal" refers to
the direction along the length of a tobacco rod (e.g., along the
axis 134 in FIG. 1), or along the length of a base web 140 (e.g.,
arrow 141 in FIG. 2) used in the preparation of wrapper that, in
turn, may be used to fabricate a tobacco rod, or in the so-called
machine-direction of a printing press, i.e., the direction through
which a base web is drawn through a print station(s).
[0041] For purposes of this disclosure, "transverse" refers to the
direction circumferentially around a tobacco rod 122 (see FIG. 1),
or transversely of a base web 140 (e.g., arrow 144 in FIG. 2) which
corresponds with the so-called cross-machine direction of a
printing press.
[0042] For purposes of this disclosure and with reference to FIGS.
1 and 2, the "width" of an individual patch element 126 or of a row
(or "zone" or "band") 131 of patch elements (e.g., row 131a)
extends in a longitudinal direction (e.g., the width extends in the
direction of axis 134 in FIG. 1 and the arrow 141 in FIG. 2).
[0043] In this specification, the unit of measurement for basis
weight, gram(s) per square meter, is abbreviated as "gsm".
[0044] When the phrase "weight percent" is used herein with respect
to the starch component of a starch solution, the "weight percent"
is the ratio of the weight of the starch to the total weight of the
starch solution. Unless noted otherwise, when the phrase "weight
percent" is used herein with respect to any component other than
the starch component of a starch solution, the "weight percent" is
the ratio of the weight of that other component to the weight of
the starch component.
[0045] For gravure printing applications, the phrase "single pass"
as used in the specification is intended to mean printing using a
single cylinder. For other application techniques, the phrase
"single pass" is intended to mean a process where the entire band
or pattern is applied at one time.
[0046] The phrases "self-extinguish under free-burn conditions" or
"self-extinguishment" as used herein, refer to the extinguishment
of a smoldering cigarette without puffing, when such cigarette is
subjected or exposed to free-burn conditions.
[0047] When the word "about" is used in this specification in
connection with a numerical value, it is intended that the
associated numerical value include a tolerance of .+-.10% around
the stated numerical value.
[0048] The terms and phrases used herein are not to be interpreted
with mathematical or geometric precision, rather geometric
terminology is to be interpreted as meaning approximating or
similar to the geometric terms and concepts. Terms such as
"generally" and "substantially" are intended to encompass both
precise meanings of the associated terms and concepts as well as to
provide reasonable latitude which is consistent with form,
function, and/or meaning.
Smoking Article with Improved Wrapper
[0049] Referring again to FIG. 1, a smoking article 120, such as a
cigarette, preferably includes a tobacco rod 122 and a filter 132
attached to the tobacco rod 122 with tipping paper 193. Preferably,
the tobacco rod 122 comprises a column of shredded tobacco ("cut
filler") and a wrapper 123 disposed about the column of tobacco,
which wrapper 123 is constructed in accordance with teachings which
follow. The tobacco rod 122 has a lightable or lit end 124 and a
tipped end 130 (which in the case of non-filter cigarettes, is
referenced as the mouth end 130 of the cigarette 120). Cut filler
tobacco is an industry-standard designation. Further, the tobacco
rod 122 typically has a generally circular cross section, although
other oval cross section and other shapes are within the scope of
this disclosure. The wrapper is sealed along a longitudinal seam
181 to form the tobacco rod 122.
[0050] The tobacco rod has a nominal length "L" measured from the
edge 130 of the tipping paper 193 to the lit end 124 of the tobacco
rod along a longitudinal axis 134 of smoking article. By way of
example, that nominal length may lie in the range of about 50 to
about 100 mm.
[0051] As shown in FIG. 2, the wrapper 123 is constructed from a
base web 140 that may be made from flax, wood pulp, cellulose
fiber, or the like, and may have a plurality of patch elements 126
applied to one or both sides of the base web 140. Preferably, the
patch elements 126 are applied to the inside of the wrapper 123 in
the sense of how the wrapper 123 surrounds a column of tobacco in
the tobacco rod 122 (shown in FIG. 1).
[0052] Preferably, the transverse dimensions of the wrapper 123 are
selected based on the diameter of the finished smoking article
(about 5 to about 10 mm) and allowing for overlapping material at a
longitudinal seam of about 1 to about 2 mm. For example, allowing
for about 2 mm overlapping seams, the wrapper-paper cross-web
dimension may be about 27 mm for a smoking article having a
circumference of about 24.8 mm.
[0053] The wrapper includes a base web which typically is permeable
to air. Permeability of wrapper is typically identified in CORESTA
units. A CORESTA unit measures paper permeability in terms of
volumetric flow rate (i.e., cm.sup.3/sec) per unit area (i.e.,
cm.sup.2) per unit pressure drop (i.e., cm of water). The base web
of conventional wrapper also has well-known basis weights, measured
in grams per square meter, abbreviated as "gsm". The permeability
and basis weight for base web of typical smoking article papers
commonly used in the industry are set out in the table below:
TABLE-US-00001 Permeability, CORESTA units Basis Weight, gsm 24 25
33 24-26 46 24-26 60 26-28
[0054] For purposes of this description, the base web of a
preferred wrapper has a permeability of at least about 20 CORESTA
units. Most preferably, the wrapper has a permeability greater than
about 30 CORESTA, such as common base webs having nominal
permeabilities of about 33 and about 46 CORESTA with a basis weight
of about 25 gsm. For some applications, the base web may have a
permeability of greater than about 60 CORESTA, or greater than
about 80 CORESTA, or even higher permeability values, with a basis
weight of about 26 gsm or greater.
[0055] Depictions of cross sections taken through a patterned
paper, such as FIGS. 7-10, are believed to be useful schematic
representations of a paper web having patch elements fashioned from
one or more layered applications, and of the application processes
by which such patterned papers are fabricated. Nevertheless, those
representations are schematic and are not scale representations of
the actual patch elements or relative paper thickness.
[0056] Each layer of add-on material may be substantially
continuous, may have a uniform or variable thickness, and/or may
have a smooth or rough surface.
[0057] Thus, schematic descriptions of paper with one or more
layers of add-on material are at significant variance with the real
world results of applying one or more layers of add-on material to
a base web 140. Accordingly, the schematic representations of
add-on layers fairly show the process application rates, as might
be used as a guide to etch application patch elements of a gravure
print cylinder or the like. However, those schematic
representations do not accurately represent the actual structure of
the finished wrapper prepared by applying one or more layers of
add-on material to a base web.
[0058] Techniques other than gravure printing may be used to
produce the desired patches 126, such a xerographic printing,
digital printing, coating or spraying using a template, or any
other suitable technique or including a separate step for
establishing material-free regions. However, single-pass, gravure
printing techniques are preferred.
Diffusivity
[0059] When using the preferred add-on solutions, base webs and
application techniques of the teachings which follow, a printing
solution, upon its application to a base web and drying, forms an
air-occlusive film on the base web that is effective to locally
reduce diffusivity values from a diffusivity level of approximately
2 cm/sec or greater (for the base web in its original condition) to
a value in the range of 0.0 to about 0.2 cm/sec, more preferably
less than approximately 0.1 cm/sec, as measured by a Sodim CO.sub.2
Diffusivity Tester (purchased from Sodim SAS of France). To measure
the diffusivity of a piece of paper using a Diffusivity Tester, the
paper is positioned within a clamping head so that the paper
separates two vertically arranged chambers. The upper chamber
contains a carrier gas, such as nitrogen, while the lower chamber
contains a marker gas, such as carbon dioxide. As there is no
pressure difference between the two chambers, any migration of
gases is due to differences in concentrations of the gases, and
there is no permeability effect, which occurs when a pressure
difference is maintained between two surfaces of the paper. After a
predetermined period of time (e.g., for a predetermined time of
about 25 seconds or less), the concentration of carbon dioxide
within the nitrogen stream of the upper chamber is measured in an
analyzer. A computer then converts the detected level of
concentration into a measure of diffusivity.
Preparation of Add-on Material
[0060] As described in U.S. Patent Application Publication No.
2008/0295854 filed May 23, 2008, the entire content of which is
incorporated by reference thereto, preferably, a film-forming
composition may be used to form the patch elements 126. The
film-forming composition comprises water and a high concentration
of an occluding agent, e.g., about 14% to about 50% by weight of
the water plus the occluding agent. The film-forming compound can
include one or more occluding agents such as starch, alginate,
cellulose, or gum and may further include calcium carbonate as a
filler. Further, the film-forming composition preferably includes
an anti-wrinkling agent. Where starch is the film-forming compound,
a concentration of about 16% to about 26% may be particularly
advantageous, and a concentration of about 21% is presently most
preferred.
[0061] To improve the ignition propensity characteristics of a
smoking article fashioned from the wrapper, the pattern is
preferably applied with a printing solution containing an oxidized
starch and formed by a process as described herein. Preferred
printing characteristics and film-forming characteristics of the
add-on material may be achieved using an aqueous oxidized starch
solution having a viscosity ranging from about 40 centiPoises (cP)
to about 80 cP as measured using a Brookfield RVDV-2 viscometer
with a #1 spindle at 20 rotations per minute (rpm) as measured at
120.degree. F., more preferably in the range of about 40 cP to
about 60 cP. At the press or at time of printing, the viscosity is
adjusted by an addition of hot water and/or heat to achieve a
preferred final, print solution having a viscosity of about 16.5 to
about 19.5 seconds, as measured by a Zahn #2 cup at 120.degree. F.,
more preferably about 17 seconds to about 19 seconds. Starch
employed for the printing solution preferably may be initially
mixed with water to form an aqueous starch mixture having a solids
content of about 29% to about 34% (by weight), more preferably
about 30% to about 33% (by weight). While various starches may be
used, for purposes of this invention it is preferred, without
limitation, to use an oxidized starch. Preferred oxidized starches
include an oxidized tapioca starch, such as FloMax.RTM. 8 available
from National Starch, LLC (now Ingredion). The type (e.g. tapioca)
and treatment (e.g. oxidation) provides starch components (e.g.
amylose and amylopectin) that are in the preferred molecular weight
range.
[0062] Preferably, the printing solution also includes
1,2-propylene glycol, in amounts sufficient to abate the tendency
of the base web to wrinkle in the course of applying and drying an
aqueous starch solution during printing (the "anti-wrinkling"
effect of propylene glycol). It is presently understood that this
effect is achieved at inclusion levels which result in there being,
in the final wrapper, a presence of propylene glycol in the bands
at a basis weight level of about 0.2 to 0.5 grams per square meter
or more. Further teachings regarding inclusion levels of propylene
glycol and other "anti-wrinkling" agents are set forth in U.S.
Patent Application Ser. No. 61/064,438, "Patterned Wrapper with an
Anti-Wrinkling Agent," filed Mar. 5, 2008, the content of which is
incorporated herein by this reference thereto.
[0063] A presently preferred solution may comprise at the press
(all percentages here being based on the total solution weight):
starch--in an amount of about 18 to about 23 wt %
(weight--percent), more preferably about 20 to about 22 wt %, and
even more preferably about 21 wt % of the total solution weight;
propylene glycol--in an amount ranging from about 7 to about 10 wt
%, more preferably about 7 to about 9 wt %, and even more
preferably about 8 wt % of the total solution weight; calcium
carbonate--in an amount in the range of about 9 to about 13 wt %,
more preferably about 10 to about 12 wt %, and even more preferably
about 11 wt % of the total solution weight; with water essentially
comprising the remainder (in an amount ranging from about 55 to
about 65 wt %, more preferably about 60 wt %).
[0064] It has been further discovered that at preferred inclusion
levels, and upon addition of propylene glycol at or near the
conclusion of cooking of the aqueous oxidized starch solution, the
propylene glycol has additional beneficial effects. Upon its
inclusion in a cooked aqueous starch solution, it abates the
tendency of the starch components to retrograde or gel, so as to
act as a stabilizing agent. It also provides anti-microbial effects
in the resulting printing solution. Both of these effects enhance
the shelf life of the printing solution. The enhanced shelf life of
the printing solution makes it possible to prepare the solution
remotely from where printing operations are to occur and to ship
the solution. As will be further explained in the teachings which
follow, the operational shelf life of the printing solution is
further enhanced by maintaining the printing solution in the range
of 120 to 150.degree. F., more preferably about 120.degree. F. to
about 140.degree. F., during transit and/or at the time of
printing. Furthermore, inclusion of propylene glycol in the process
as taught herein also has the effect of reducing the printing
solution's viscosity to levels which further promote its
printability.
[0065] Preferably, a conventional filler material, such as calcium
carbonate, may be included in the printing solution, as desired, to
lighten the printed material to make it less visible on the wrapper
and to improve self extinguishment performance of the finished
smoking article. Preferably, if included, the calcium carbonate is
added to the printing solution just before printing. The calcium
carbonate may also help abate wrinkling of the wrapper by reducing
the water content in the applied solution. Preferably, the printing
solution has a pH in the range of about 4 to about 8, more
preferably about 7 to about 8 after calcium carbonate has been
added thereto.
[0066] Furthermore, the predetermined pattern of printing solution
is typically applied to a base web having a permeability in the
range of about 10 to about 80 CORESTA units. Preferably, the
printing solution forms a film on the base web, when dry, that is
effective to locally reduce diffusivity values in the range of 0 to
about 0.20 centimeters per second (cm/sec) as measured by a Sodim
CO.sub.2 Diffusivity Tester (available from Sodim SAS of France,
more preferably diffusivity values in the range of 0 to about 0.10
cm/sec.
[0067] Various balances or trade-offs need to be made in selection
of starch parameters for use in applying films to wrapper. For
example, while high molecular weight starch may give rise to
effective diffusivity reduction, such high molecular weight
starches are of lower solubility, and consequently, must be used in
lower concentrations, resulting in a printing solution and with
very high water content, which elevates drying requirements and
exacerbates the wrinkling of the base web.
[0068] In the preferred embodiment, as shown in FIG. 3, the
printing solution is prepared by adding water 200 and adding
oxidized starch 205 to a container in a batch process. The
preferred embodiment provides a batch process. In the batch
process, the water and an oxidized starch are mixed (step 210) at
about 75.degree. F. at low speeds of about 15 rotations per minute
(rpm) to disperse the starch granules in water and form an aqueous
oxidized starch mixture having a pH in the range of about 4 to
about 5.5. In the preferred embodiment, the water may be heated to
about 75.degree. F. or more before adding (step 205) the oxidized
starch thereto. Upon mixing (step 210), the oxidized starch mixture
is then heated (step 220) to a temperature in the range of at least
about 180.degree. F. to at least about 200.degree. F., more
preferably about 195.degree. F. Preferably, the temperature is
raised over a preferred time interval of about 60 to about 90
minutes, preferably with agitation so as to assure uniformity. Also
preferably, the temperature of the heated oxidized starch mixture
is then "cooked" by maintaining (step 230) the solution at the
aforementioned selected temperature in the range of about
180.degree. F. to about 200.degree. F., preferably at about
195.degree. F. while mixing for at least about 30 minutes, more
preferably at least about 45 minutes. During the heating and
maintaining steps, the starch granules (detectable under a
microscope) are believed to absorb water, swell, rupture, and
release amylose and/or amylopectin into the solution.
[0069] After the heating (step 220) and the maintaining (step 230)
the temperature of the aqueous oxidized starch solution, the
process preferably also includes adding (step 250) propylene glycol
to the aqueous oxidized starch solution and mixing (step 260) while
holding the temperature substantially constant either at
aforementioned, selected temperature, or more preferably, at or
about 180.degree. F. If, when adding propylene glycol, it is at
room temperature, the temperature of the solution may drop from the
aforementioned 195.degree. F. to a temperature of about 180.degree.
F. Once the propylene glycol is added (step 250), the aqueous
oxidized starch solution is mixed for at least about 30 minutes to
thoroughly disperse the propylene glycol throughout the aqueous
oxidized starch solution.
[0070] Preferably, the aqueous oxidized starch solution is
continuously mixed during the heating (step 220), the maintaining
(step 230), and after the adding (step 250). Preferably, the
propylene glycol is maintained at room temperature or higher before
its addition to the aqueous oxidized starch solution. Moreover, the
propylene glycol is preferably added as quickly as possible to the
aqueous oxidized starch solution. In a batch process, for example,
the aqueous oxidized starch mixture can be mixed using low speed,
low shear mixing of about 15 rpm in a 1000 gallon tank during the
heating (step 220), during the maintaining (step 230), and after
the adding propylene glycol to the aqueous oxidized starch solution
(step 250). Preferably, the mixing (step 260) is conducted while
the solution is at an elevated temperature, preferably at about
180.degree. F. or above.
[0071] In an alternative embodiment, the heating (step 220) can be
accomplished by use of a jet cooker, which produces cooked starch
on a substantially continuous basis "on demand", where liquid
heated to at least about 180.degree. C. is jetted against an
impaction surface to break-up granular structures of the starch in
the liquid.
[0072] Not wishing to be bound by theory, it is believed that by
maintaining the temperature of the aqueous oxidized starch mixture
at or above about 195.degree. F., any remaining starch granules are
caused to swell, rupture, and release amylose and/or amylopectin
therefrom. By adding propylene glycol thereafter, it is believed
that the propylene glycol substantially abates recombination
thereof so that the film forming capability/capacity of the starch
printing solution is preserved for an extended period of time.
Moreover, the propylene glycol stays in solution with the starch to
provide a substantially homogenous mixture having a low viscosity
of less than about 100 cP, more preferably less than about 60 cP,
more preferably about 40 cP to about 60 cP when measured using a
Brookfield RVDV-2 viscometer with a #1 spindle at 20 rpm at
120.degree. F.
[0073] Moreover, it is believed that the addition of propylene
glycol to the aqueous oxidized starch solution provides stability
and anti-microbial effects, and therefore, improved shelf-life to
the printing solution. These effects are evidenced by the solution
pH, which does not change (i.e., is substantially constant) for
several days after the printing solution has been prepared.
[0074] After addition of propylene glycol (step 250) and the mixing
(step 260), the printing solution may be cooled (step 240) to a
temperature ranging from about 120.degree. F. to about 140.degree.
F. Preferably, the printing solution is maintained at a temperature
at about or greater than about 120.degree. F. to avoid
agglomeration and viscosity increase. It has been found that as the
solution temperature drops below about 100.degree. F.,
retrogradation accelerates resulting in undesired gelling of the
solution. Once the gelling effect begins, the retrograded condition
of the solution is irreversible.
[0075] At a temperature of about 120.degree. F., the printing
solution prior to initiation of printing operations preferably has
a viscosity of about 40 cP to about 60 cP as measured using a
Brookfield RVDV-2 viscometer with a #1 spindle at 20 rpm at
120.degree. F. Also preferably, at a temperature of about
120.degree. F. the printing solution has a pH of about 4 to about
5. At the press, just prior to initiation of printing operations
either an addition of hot water or an increase in temperature (not
higher than 150.degree. F.) or both may be used to achieve a
desired, final printing viscosity (in the range of about 16.5 to
19.5 sec, more preferably about 17 to 19 sec).
[0076] In one embodiment, the printing solution may then be stored
in drums/totes and at a temperature of about 120.degree. to about
140.degree. F. until use at the time of printing. The drums/totes
can be transported using an insulated blanket or heated truck, as
needed, while maintaining the drums at a temperature of at least
about 120.degree. F. The drums/totes can also be stored under
heated conditions. In the preferred embodiment, the printing
solution may also be continuously agitated at low speed during
storage. Preferably, the printing solution is used within 72 hours
of production. The aforementioned maintenance of temperature,
together with the addition of the propylene glycol provide
stability to the solution such that a shelf-life of at least 2 or 3
days or longer is achievable.
[0077] In the preferred embodiment, the process may also preferably
include adding (step 270) calcium carbonate to the printing
solution. In the preferred embodiment, about 300 pounds of the
printing solution can be mixed with about 40 pounds of water and
about 40 pounds of calcium carbonate while mixing for about 15 to
about 25 minutes. Preferably, the mixture is mixed using a Neptune
impeller at low speed to suspend the calcium carbonate (or chalk)
in the mixture, avoid foaming, and form a printing solution. The
calcium carbonate is preferably added just before printing so that
the calcium carbonate does not settle out of solution.
[0078] At the converter/printer, the printing solution can then be
pumped to a run drum of a printing press. Preferably, the final
printing solution (after addition of water and calcium carbonate)
has a pH of about 7 to about 8 and a viscosity of about 20 cP as
measured using a Brookfield RVDV-2 viscometer with a #1 spindle at
20 rpm at 120.degree. F.
[0079] At the press, the process also includes providing a base web
of wrapper (step 280) and applying the printing solution to the
base web to form a cigarette wrapper (step 290).
[0080] In the preferred embodiment, the printing solution allows
for higher starch loading to the base web, uses less water, and the
propylene glycol has a greater anti-wrinkling effect due to a
higher concentration of propylene glycol with respect to the water
content. These features synergistically substantially reduce
wrinkling of the base web and reduce the viscosity of the printing
solution so as to enhance printability. For example, after
application to a 33 CORESTA base web for a 6.8 mm wide solid band,
with a 27 mm band period, about 0.9 grams per square meter
(g/m.sup.2) starch, about 0.4 g/m.sup.2 propylene glycol and about
0.4 g/m.sup.2 calcium carbonate is deposited on the base web.
[0081] The following examples are given to illustrate embodiments
of the process described herein and should not be construed to
limit the scope of such embodiments.
Example 1
[0082] Oxidized starch and water are mixed at about 75.degree. F.
and heated to about 195.degree. F. for about 45 minutes with low
agitation (low shear mixing) to form a mixture. Propylene glycol is
added thereto while mixing for about 30 more minutes while
maintaining the solution at a temperature of at least about
180.degree. F. The solution is cooled to a temperature of about
140.degree. F. while mixing. The solution is then packed and the
temperature of the solution is maintained at a temperature ranging
from about 120.degree. F. to about 140.degree. F. and transported
to a location of a press.
[0083] The solution contains about 31% (by weight) starch, about
10% (by weight) propylene glycol and about 59% (by weight) water.
At the press or printing operation, about 300 pounds of the
solution is then mixed with 40 pounds hot water and about 40 pounds
calcium carbonate to form a printing solution having about 21% (by
weight) starch, about 8% (by weight) propylene glycol, about 60%
(by weight) water and about 11% (by weight) calcium carbonate to
form a final, preferred printing solution.
[0084] The solution exhibited desired printability and film-forming
characteristics.
Example 2
[0085] About 51 pounds water heated to a temperature of about
70.degree. F. to about 80.degree. F. is mixed with about 31 pounds
of starch powder, such as FloMax.RTM. 8 available from National
Starch, LLC (now Ingredion). The water and starch powder are
further mixed while heating for about 45 minutes to a temperature
of about 200.degree. F. to form an aqueous oxidized starch
solution. About 10 pounds of either condensed steam or additional
water heated to about 200.degree. F. is added to the aqueous
oxidized starch solution. The aqueous oxidized starch solution is
tested using an oven bake method and has a solids content of about
31%. The viscosity is tested using a Brookfield RVDV-2 viscometer
with a #1 spindle at 20 rpm at 120.degree. F., and the aqueous
oxidized starch solution is found to have a viscosity of about 50
cP. The aqueous oxidized starch solution has a pH of about 4 to
about 5.
[0086] About 8 pounds of propylene glycol are then added to the
aqueous oxidized starch solution and is mixed for about 30 minutes
at a temperature ranging from about 180.degree. F. to about
200.degree. F. The printing solution is then cooled to a
temperature of about 130.degree. F. The viscosity is tested again
using a Brookfield RVDV-2 viscometer with a #1 spindle at 20 rpm at
120.degree. F., and the printing solution is found to have a
viscosity of about 45 cP. Such evidences the favorable effect of
the propylene glycol to reduce viscosity. The printing solution is
kept under substantially constant agitation, the intensity of which
is dependent upon tank size, dimensions and agitator type. Calcium
carbonate is added while mixing to suspend the calcium carbonate
and form a printing solution which is maintained at a temperature
of about 120.degree. F. to about 130.degree. F. The printing
solution contains about 54.5 pounds of water, about 24.5 pounds of
pounds starch, about 10.5 pounds calcium carbonate, and about 10.5
pounds propylene glycol; and has a viscosity of about 17.5 sec to
about 18.5 sec as measured by a Zahn #2 cup at 120.degree. F.
[0087] As an alternative, turbidity of the aqueous oxidized starch
and propylene glycol solution can also be measured to identify
changes in the aqueous oxidized starch and propylene glycol
solution before viscosity changes are noticed using viscosity
measurements. Turbidity measures the amount of light transmitted
through a given quantity of material, and can thus be used as a
quality control tool to determine if the aqueous oxidized starch
and propylene glycol solution should be used or discarded prior to
mixing with calcium carbonate. Thus, the turbidity measurement can
be used to determine the film-forming capability of the aqueous
oxidized starch and propylene glycol solution.
[0088] In practicing the preferred embodiment of this invention,
the step of maintaining the solution temperature in the range of
about 120.degree. to about 150.degree. F. provides numerous
advantages including, without limitation, permitting high starch
content to be attained and maintained in the aqueous solution and
lowering the aqueous solution's viscosity. Accordingly, through use
of the temperature maintenance step until the printing step, a
desired printing solution is achieved, which solution is suitable
for a single pass application to a base web.
[0089] When propylene glycol is applied as an anti-wrinkling agent
in accordance with this specification, the propylene glycol also
counteracts the tendency of certain microorganisms to thrive in a
starch solution at a temperature in the range of about 120.degree.
to about 150.degree. F.
[0090] The film-forming composition may be applied to the base web
of the wrapper 140 using gravure printing, digital printing,
coating or spraying using a template, or any other suitable
technique. Because of the intricate dimensions of the material-free
regions of the various embodiments, a single-pass gravure printing
operation is preferred. However, if desired, the patch elements 126
of add-on material can be formed by printing multiple, successive
layers, e.g., two or more successive layers registered or aligned
with one another.
[0091] For single-pass gravure printing operations, the preferred
aqueous starch solution comprises at least 25% starch by weight;
between about 20% and about 35% anti-wrinkling agent (preferably
propylene glycol), and between about 30% and about 80% chalk
(preferably a fine calcium carbonate) (percentages here being based
on percent of starch weight). More preferably, the solution may
comprise at the press (all percentages here being based on the
total solution weight): starch--in an amount of about 18 to about
23 wt % (weight--percent), more preferably about 20 to about 22 wt
%, and even more preferably about 21 wt % of the total solution
weight; propylene glycol--in an amount ranging from about 7 to
about 10 wt %, more preferably about 7 to about 9 wt %, and even
more preferably about 8 wt % of the total solution weight; calcium
carbonate--in an amount in the range of about 9 to about 13 wt %,
more preferably about 10 to about 12 wt %, and even more preferably
about 11 wt % of the total solution weight; with water essentially
comprising the remainder (in an amount ranging from about 55 to
about 65 wt %, more preferably about 60 wt %). Preferably the
aqueous starch solution is applied at the press at a temperature
between about 120 to 140.degree. F. and is preferably prepared and
applied in accordance with those and other teachings of the U.S.
patent application Ser. No. 13/324,747, filed Dec. 13, 2011,
(Attorney Docket No. 1021238-001292), the entirety of which is
incorporated herein by reference.
[0092] For multi-pass operations, a preferred aqueous solution may
comprise approximately 16% starch, 6% chalk or calcium carbonate,
and 6% 1,2 propylene glycol (weight percents of solution).
[0093] With inclusion of the chalk in this embodiment as described,
one may abate the tendency of the patterned paper cigarettes to
self-extinguish, enhance appearance of the product to a consumer
and achieve these and other associated advantages.
[0094] The inclusion of an anti-wrinkling agent (preferably, such
as propylene glycol) in an aqueous starch solution used to make
patterned wrapper in a manner consistent with the teaching herein
can reduce transverse shrinkage to operationally manageable levels,
alleviate pronounced wrinkling and essentially eliminate creasing
problems that previously presented themselves. Inclusion of an
anti-wrinkling agent has been found to have additional benefits,
too. Cracking and flaking at patch elements are believed to be
alleviated. In addition, it is believed that the presence of the
anti-wrinkling agent appears to cause the starch solution to reside
more on the surface of the base web with less penetration into that
material, and thus enhance film formation. Shrinkage of the wrapper
in the vicinity of patch elements formed from an aqueous starch
solution that includes an anti-wrinkling agent has been observed to
be in the range of about 0.0625 to 0.125 in. for a 36 in. wide base
web--a range which does not result in creasing nor excessive
waviness in the base web. Furthermore, inclusion of an
anti-wrinkling agent in the aqueous starch solution has been found
to make possible the application of add-on material to be applied
to the base web in a single application, printing pass, or the
like, provided that sufficient drying capability is established
with such practices. In addition, the shelf life of the aqueous
starch solution is materially improved by the inclusion of an
anti-wrinkling agent as disclosed herein.
Cigarette Wrapper with Patch Elements
[0095] Referring now to FIG. 2, the patch elements 126 of add-on
material determine and regulate the IP and SE characteristics of
the smoking article. Those patch elements 126 of add-on material
are applied to a base web 140 (see FIG. 2) of the wrapper 123,
which is then formed into a tobacco rod in conventional cigarette
making equipment. Nominal permeability of the base web 140 may be
in the range of about 20 to about 100 CORESTA. Currently, the
preferred nominal permeability of the base web lies in the range of
about 30 to about 70 CORESTA, with the most preferred nominal
permeabilities being about 33 and about 60 CORESTA.
[0096] The manufacture of base web 140 preferably includes the
production of a roll of base web of several feet across (usually
about 3 to four feet across or in transverse dimension). The base
web is then drawn through a printing press or the like and rewound
to produce a roll of patterned paper, which is then slit into
bobbins. With reference also to FIG. 2, the base web 140 is in
effect slit along the longitudinal lines 145a, 145b, which has a
transverse dimension correlating with the nominal circumference of
the smoking article with accommodation for overlap along the seam,
as previously discussed. Preferably, pairs of patch elements 126
(such as the patch elements 134a, 136a) are established between the
lines 145a and 145b, which preferably locate at opposite sides of
the tobacco rod 122 in FIG. 1 to establish a row 131 of patch
elements.
[0097] Each pair of rectangular patches (for example, patches 134a
and 136a--the latter not being visible in FIG. 1) define a
circumferential patch row 131 (or "zone" or "band") (for example,
the row 131a). Preferably, the "width" of the row 131, or the width
of each of the two patch elements 134a and 136a of the row 131a is
in the range of about 5 to about 10 mm, more preferably, in the
range of about 6 to about 9 mm, and even more preferably, in the
range of about 6.5 to about 8.5 mm. Moreover, at each
circumferential region, such as row 131a, the patch elements 134a
and 136a are circumferentially spaced apart such that they are
disposed in mutually opposing relation along opposite sides of the
wrapper 124 when formed on a tobacco rod 122. Preferably the patch
elements 134a, 136a are circumferentially spaced apart from one
another such that they are disposed in a mutually opposing relation
along opposite sides of the wrapper 123 of the tobacco rod 122.
Preferably, each patch 134a, 136a extends circumferentially (i.e.,
in cross-measure relative to the paper web) in the range of about 6
to about 10 mm in cross-measure, more preferably, about 7 to about
9 mm in cross-measure, and even more preferably about 7.5 mm to
about 8.5 mm in cross measure.
[0098] It is further noted that the portion 133 of base web 140
outside of the patch elements 126 are preferably, essentially free
of add-on material. More particularly, the areas between adjacent
regions 131a, 131b and the areas between opposing elements within
each region (such as between the opposing elements 134b, 136b of
the region 131b) are preferably essentially free of add-on material
comprising the patch elements (e.g., patch elements 134b,
136b).
[0099] The longitudinal distance between adjacent regions (such as
between rows 131a, 131b, see FIG. 1) is referenced as row spacing
137 (or band spacing 137), which is preferably about 6 to about 12
mm, and more preferably about 7 to about 11 mm, and even more
preferably about 8 to about 10 mm.
[0100] Preferably, the respective patch elements 126 (see FIGS. 1
and 2) of adjacent rows 131a, b, c, d are circumferentially off-set
from one another, more preferably, each of the second, third and
fourth rows 131b, c, and d respectively, are increasingly off-set
from the first row 131a, and together all four rows 131a, b, c, d
define a set of rows 139 (or row set 139). Preferably, a sufficient
number of regions 131 are established along a given tobacco rod
(per selection of band-region width and width of band spacing)
that, when the smoking article is placed up on a substrate, that
there occurs at least one location along the tobacco rod 122 where
the respective pair of patch elements 134 are oriented
substantially alongside the tobacco rod 122, such as the opposing
pair of patch elements 131b in FIG. 1, and a second patch, not
shown, on the opposite side of the tobacco rod. It is at or about
this portion (location 301) of the tobacco rod 122 where
extinguishment is most likely to occur when the smoking article 120
is left to smolder on a substrate. The location along the tobacco
rod 122 where this orientation most closely occurs is hereinafter
referenced as the "snuffer region 301."
[0101] Preferably, four or more patch rows are provided along the
nominal length of a tobacco rod. Furthermore, preferably the
patches of each patch row 131 are circumferentially offset from the
patches of the adjacent patch rows. That offset may be selected
such that the patches are offset from one another relative to the
axis 134 of the tobacco rod by an angle in the range of about
40.degree. to about 75.degree., more preferably in the range of
about 45.degree. to about 60.degree., and most preferably about
45.degree..
[0102] Because any particular smoking article 120 might be laid
upon a substrate differently from the orientation shown in FIG. 1
and/or because its pattern of patch elements may differ, it is to
be realized that the oriented snuffer region 301 may appear at
different longitudinal positions along the tobacco rod 122 for
different rotational positions of the tobacco rod 122. The pattern
of patch elements and the band spacing 137 may be selected such
that more than one oriented snuffer region 301 may occur along the
tobacco rod 122.
[0103] Preferably, each patch element 134, 136 includes sufficient
add-on material to reduce the diffusivity of the wrapper at each
patch element to 0.0 to about 0.2 cm/sec, and more preferably to
the range of 0.0 to about 0.1 cm/sec.
[0104] As presently understood, the staggered patch rows of add-on
material according to this description permit a smoking article 120
(see FIG. 1) to be designed with an advantageous combination of low
IP values and low SE values. The patterns of low permeability patch
elements of add-on material provide areas of film-forming compound
along the length of the tobacco rod 122 that can cooperate with a
substrate to extinguish the lit smoking article 120 when it is
placed on that substrate, yet these areas of add-on material (such
as a film-forming compound) cause the smoking article 120 to
self-extinguish at statistically fewer occurrences when the smoking
article 120 is held by an adult smoker in a free-burn condition.
Thus, the smoking article 120 can exhibit a reduced ignition
propensity while retaining a desirable free-burn quality or low SE
value by applying a pattern 130 of film-forming compound to the
base web according to this description.
[0105] To achieve desirable IP and SE characteristics of the
smoking article, a pattern 130 (see FIG. 2) is applied to the base
web 140 of the wrapper paper, preferably while the base web 140 is
in an unfolded condition, such as shown in FIG. 2, or when the base
web comprises a roll of cigarette paper that has yet to be slit
into bobbins. An object of this description is to provide wrapper
papers which, when formed into a tobacco rod 122, exhibit IP values
no greater than 25 and SE values no greater than 50. Even more
preferred, is an IP value for the resulting smoking article no
greater than about 15; and the most preferred IP value for the
resulting smoking article is no greater than about 10. Lower SE
values are also desired. In this connection, a more preferred SE
value is less than about 25; while the most preferred SE value is
less than about 10.
[0106] Preferably, the pattern is applied to the base web such that
a plurality of circumferentially extending rows 131a, 131b, 131c,
131d are disposed at spaced locations along the tobacco rod 122.
The add-on material can be applied to one or to both sides of the
base web. Preferably, three to six, and most preferably four to six
or more, of the rows 131 occur in the nominal length of the tobacco
rod 122. More particularly, a row set 139 in a preferred embodiment
comprises four rows 131, but could be a fewer or a greater number
of rows. Generally, the configuration of patch elements 126 are
configured amongst the rows of a given row set 139 such that the
occurrence of a snuffer region 301 is assured when the smoking
article 122 is placed upon a substrate as previously explained. The
occurrence of a complete row set is then assured by making the unit
length of a row set 139 (as represented by the designation 139 in
FIG. 2) less than the nominal length of the tobacco rod. More
particularly, it is desired that an integral number of rows occurs
in that nominal length of the tobacco rod. The nominal length of
the tobacco rod may, for example, be about 54 mm. By way of
example, and without limitation, where four rows of patches having
an 8 mm length in the longitudinal direction are used, the spacing
between adjacent rows (in the longitudinal direction) would be
about 5.5 mm.
[0107] Each of the circumferential rows 131a, 131b, 131c, 131d has
a longitudinal pitch or period along the tobacco rod 122 (i.e.,
length measured along the tobacco rod from the beginning of one row
to the beginning of the adjacent row) which is less than the
nominal length of the tobacco rod 122. By selecting the
longitudinal pitch length or period at about 25% of the nominal
length, four rows will be provided on each tobacco rod 122.
[0108] Preferably, the pattern corresponding to row sets 139 may
repeat itself at least partially along the length of the tobacco
rod 122 and it is envisioned to configure the unit length of a row
set 139 such that a multiple of row sets may occur along a tobacco
rod 122.
[0109] When wrapper paper 140 is formed about tobacco to make a
tobacco rod 122, patch elements of add-on material at any
longitudinal location are preferably spaced about 180 degrees from
each other. Moreover, the ratio of the printed area to available
surface area (the area of patch elements of a given patch row
divided by the circumference of the smoking article times the width
of the patch row and the spacing between adjacent patch rows--that
ratio here being defined as the "printed area ratio") is
substantially less than one. Preferably, the zone area ratio lies
in the range of less than about 20% to less than about 50%, and
more preferably in the range of less than about 20% to less than
about 35%. More particularly, in some embodiments the zone area
ratio for element-occupied area to total area may be less than 30%,
and even less that 25%. Generally speaking, it is desirable to keep
the zone area coverage ratio low because high values (i.e., closer
to 1) are believed to increase carbon monoxide concentration in
mainstream smoke.
[0110] The patch elements of the pattern 130 may be formed by
applying one or more layers of an aqueous film-forming composition
to the base web of the wrapper paper to reduce the permeability of
the paper in those patch elements. Alternatively, a cellulosic
material may also be used to form the patch elements. Where a
film-forming composition is used, that film-forming composition
preferably may include water and a high concentration of an
occluding agent, e.g., 20% to about 50% by weight. The film-forming
compound can include one or more occluding agents such as starch,
alginate, cellulose or gum and may also include calcium carbonate
as a filler. Where starch is the film-forming compound, a
concentration of about 21% may be advantageous. The film-forming
composition may be applied to the base web of the wrapper paper 123
using gravure printing, digital printing, coating or spraying using
a template, or any other suitable technique. For example, the
film-forming compounds and methods for applying film-forming
compounds described in U.S. application Ser. No. 11/500,918, which
is hereby incorporated herein in its entirety by this reference
thereto, may be chosen for applying a pattern to the base web of
the wrapper paper. If desired, the patch elements of add-on
material can be formed by printing multiple, successive layers,
e.g., two or more successive layers registered or aligned with one
another. Furthermore, when layers are used to form the patch
elements of add-on material, the material in layers may be the same
of different. For example, one layer may be starch while the next
layer may be starch and calcium carbonate (or vice versa).
[0111] The presently preferred embodiment for the pattern 139 of
patch elements of add-on material is illustrated in FIG. 2. The
patch elements of add-on material are quadrilateral, specifically,
generally rectangular, or generally square.
[0112] The circumferential offset, x, between (i) the patch
elements 134a, 136a of the row 131a and (ii) the corresponding
patch elements 134b, 136b of the adjacent row 131b preferably lies
in the range of about 10% to about 35% of the total, unwrapped
cross-measure of the bobbin. More preferably, the circumferential
offset, x, lies in the range of about 12% to about 35% of the
total, unwrapped cross-measure of the bobbin 140. Most preferably,
the circumferential offset, x, is about half the circumferential
dimension or cross-measure of the add-on row. The patch elements of
add-on material in other rows, 131c, 131d, are likewise further
offset circumferentially by the same offset, x, with respect to
each other. In an embodiment, each row 131 of a row set 139 may be
offset from one another in the range of about 3.5 to about 4 mm in
the transverse direction, and in one example, by about 3.375 mm for
a row set 139 of four rows 131 and a tobacco rod circumference of
about 25 mm.
[0113] The pattern applied to establish rows 131a-131d is
preferably repeated along the length of the base web 140. Clearly,
if the circumferential offset, x, is less than 12.5% of the
cross-directional width of the bobbin, more than four rows will
define a complete cycle or phase length or pitch for the pattern
130. Conversely, if the circumferential offset, x, is greater than
12.5%, less than four rows will define a complete cycle for the
pattern 139 (as in the case of the FIG. 2 pattern).
[0114] Three different positions of the smoking article 120 resting
on substrate 198 are illustrative of the cooperation which occurs
between the patch elements of low permeability add-on material and
the substrate 198. One position (see FIG. 4) illustrates a side
view of the smoking article 120 according to this description.
Rotation of the smoking article through a 45.degree. angle about
its longitudinal axis (clockwise from the left end of FIG. 4)
results in an elevation similar to that shown in FIG. 5. Similarly,
further rotation of the smoking article 120 through another
45.degree. angle (also clockwise from the left end of FIG. 4)
results in an elevation to that illustrated in FIG. 6. In each of
FIGS. 4-6 it can be seen that at least one pair of patch elements
of add-on material are positioned on the sides of the smoking
article at a location along the length of the tobacco rod 122,
e.g., patch elements 192, 192' (not shown) of FIG. 4, patch
elements 194, 194' of FIG. 5, and patch elements 196, 196' of FIG.
6. At those locations where the patch elements of add-on material
are positioned substantially on the sides of the smoking article
120 (FIG. 10), the patch elements 192, 192' are substantially
upright or generally perpendicular to the surface of the substrate
198. That orientation of the patch elements 192, 192' is best
illustrated in FIG. 11, where the opposed patch elements 192, 192'
are located on corresponding opposed sides of the smoking article
120 when viewed in cross section, substantially symmetrically
positioned relative to a diameter of the tobacco rod 122, which
diameter is substantially parallel to the surface of the substrate
198.
[0115] Orientation of the patch elements of add-on material at
other longitudinal locations along the smoking article 120 are
shown in FIGS. 7-9. In FIG. 7, the patch elements 190, 190' of
add-on material are positioned such that one patch element 90
touches the substrate 198. In FIG. 9, one patch element 196'
contacts the substrate 198, but the other opposed patch element 196
is located at the top of the smoking article 20. From consideration
of FIGS. 7-9, it will be appreciated that regardless of the angular
position of a smoking article 120 having the pattern of patch
elements of add-on material described, at least one pair of opposed
patch elements of add-on material are substantially positioned as
shown in FIG. 10, or a slightly rotated position close thereto.
This position has been referred to above as the oriented snuffer
region 301.
[0116] When the smoking article 120 exists in free-burn condition
(see FIG. 11), the patch elements 192, 192' obstruct airflow to the
burning coal of the tobacco rod 122 by virtue of their reduced
permeability. On the other hand, the bottom portion 304 of the
wrapper paper freely permits air to enter the bottom or bottom side
of the tobacco rod 122 to support combustion of the coal. A vastly
different situation occurs when the smoking article 120 is placed
on a substrate 198 (see FIG. 10). Here, the substrate 198 blocks
the flow of air upwardly to the bottom portion 190 of the tobacco
rod 122. The patch elements 192, 192' and the substrate 198
cooperate to define much smaller areas 300, 302 through which air
can be delivered through the base web. More specifically, the
vertical area 300 between the bottom of the patch element 192 and
the substrate 198 and the vertical area 302 between the bottom of
the patch element 192' and the substrate 198 present a substantial
reduction in the area through which air can pass to reach the
smoldering coal of the tobacco rod 122. As a result of deprivation
of oxygen in the air, the smoldering coal self-extinguishes when
the burn line reaches opposed patch elements of add-on material
positioned as depicted in FIG. 10. The condition of substantially
reduced area for air to support burning of the coal also exists for
rotational positions of the tobacco rod 122 between that position
illustrated in FIG. 10 and the position illustrated in FIG. 7 when
the patch elements of add-on material do not contact the substrate
198, with FIG. 10 representing the position of most reduction in
the area accessible to airflow. Similarly, if the smoking article
is placed on a substrate 198 in a position where any of the other
pairs of patch elements of add-on material have substantially the
position shown in FIG. 10, self-extinction will also likely occur
at such other pairs of patch elements.
[0117] However, when the smoking article is placed on the substrate
198 such that one of the add-on patch elements contacts the
substrate 198, substantially as shown in FIG. 9, the add-on patch
elements may sufficiently restrict the area through which air can
pass to the base web, and there is a lesser degree of material
cooperation between the substrate 198 and the add-on patch elements
to effect a reduction in that area, in comparison to what occurs at
the snuffer region(s) 301.
[0118] In the foregoing example, the reduction in IP value,
reduction in SE value, and improved free-burn quality of a smoking
article 120 having a wrapping paper with pattern 139 formed thereon
is discussed in relation to a situation where the smoking article
happens to be placed on a substrate 198 at one of three specific
orientations, the orientations being spaced (off-set) 45.degree.
apart from each other. Naturally, the discussion proceeded in this
manner for the sake of brevity. It will be readily understood that
a pattern according to this description can extinguish the smoking
article, regardless of which side portion rests against a substrate
198 and without a need for applying film-forming compound to the
paper to such an extent that a desirable free-burn quality in the
smoking article is lost. This may be understood by recognizing that
opposing patch elements of film-forming compound need not appear at
locations exactly 90 degrees from the side portion in contact with
the substrate 198. Those patch elements may be centered at a
location that is closer to or farther from the side portion in
contact with the substrate 198, for example, between about
60.degree. and 120.degree. from the side portion in contact with
the substrate 198. It is also contemplated that more than two patch
elements 126 may comprise each row 131 of patches about a
circumference of a smoking article 120.
[0119] Additionally, for a particular chosen pattern, the ability
to extinguish the smoking article may depend more on providing
minimum lengthwise extent of add-on material (e.g., a film-forming
compound), rather than a particular weight per area of film-forming
compound at longitudinal locations. The length of a rectangular
patch element or patch, for example, may be no less than about 7 mm
for a particular design, base web, and film-forming compound used.
The amount of film-forming compound used may be increased to
improve IP performance, usually without losing a free-burn quality,
and if desired, a burn accelerator may be applied to the paper to
support even higher add-on levels.
[0120] Preferably, the patches of add-on material reduce
diffusivity of the wrapper paper to the range of from about 0 to
about 0.2 cm/sec, and more preferably to the range of from about 0
to about 0.1 cm/sec.
[0121] Accordingly it is seen that the spirally rotated position of
the opposed patch elements of add-on material creates a situation
where, regardless of which side portion of the wrapper paper is
placed against the substrate 198, there will always be at least one
longitudinal location along the tobacco rod having patch elements
disposed along opposite sides of the tobacco rod, not in contact
with the substrate 198 yet having a sufficient geometry and add-on
material to extinguish a smoldering smoking article when left
unattended on the substrate 198. The arrangement permits a smoking
article to be designed with an IP value no greater than 25% or
less. In that each row 131 of patches includes uncoated areas
between patch elements 126, the smoking article has a significantly
improved SE performance during free burn. The arrangement enables a
smoking article to be designed with an SE value of less than 50%
and may be less than 25%.
[0122] In the embodiments described above, the smoking article has
a generally circular cross section. Therefore, it is possible for
any side portion of the smoking article to rest against the
substrate 198. However, a pattern as taught herein can be such that
the burn characteristics described above (IP values no greater than
25% and SE values no greater than 50%) in relation to FIGS. 10 and
11 can be realized, regardless of which side portion of the smoking
article happens to rest against the substrate 198. Preferably, the
pattern is selected so that when the base web is wrapped around a
tobacco rod 122, patch elements of film-forming compound appear at
opposing sides not in contact with the substrate 198 at one or more
longitudinal locations along the tobacco rod 122. Having more than
one longitudinal location with film-forming compound at the side
positions is preferred so as to accommodate situations where the
smoking article is placed on a substrate 198 after the burn line
has advanced through a portion of the smoking article which would
have extinguished the smoking article, or so that side patch
elements of add-on material are always relatively close to a burn
line when the smoking article is placed on the substrate 198.
[0123] If desired, the patch elements of add-on material may also
comprise other geometric shapes other than quadrilaterals
including, for example, ovals, other polygons, or the like.
[0124] The patch elements 126 of add-on material may be applied to
the base web 140 preferably by a printing technique. While one or
more printing technique (selected from the group consisting of
direct printing, offset printing, inkjet printing, gravure
printing, and the like) may be used to apply the patch element 126,
preferably a gravure printing process will be used. Gravure
printing provides ample control over deposition rates, deposition
patterns, and the like, and is suitable for high-speed printing on
the base web 140. For purposes of this disclosure, "high-speed"
printing refers to printing processes where the base web 140
advances through the printing process at a linear speed greater
than about 300 feet/min. For cigarette manufacturing purposes, base
web printing speeds greater than 450 feet/min. are preferred, and
speeds greater than 500 feet/minute or more are even more
preferred. In this regard, the rates of deposition for add-on
material, as well as the quality of the pattern of deposited add-on
material, can vary considerably when wrapper prepared by high-speed
printing processes is compared with wrapper prepared by low-speed
printing processes. Higher-speed printing operations can achieve
production of wrappers capable of providing both desirable IP
values (performance) and desired SE values (performance).
[0125] Remarkably, it has been found that a base web may be
converted (printed) to include patch elements in accordance with
the embodiment described with reference to FIGS. 1 and 2 at about
1000 feet per minute with acceptable paper appearance (i.e.,
without quality defects) and without elevated or unacceptable
statistical occurrences of creases or wrinkles.
[0126] This disclosure contemplates that various anti-wrinkling
agents are suitable to attain the desired characteristics described
herein. In particular, the anti-wrinkling agent is selected from
the group consisting of glycerin, propylene glycol, and 1,2
propylene glycol. Propylene glycol is a preferred member of the
anti-wrinkling agent group, however, 1,2 propylene glycol is the
most preferred member of the anti-wrinkling agent group.
[0127] Patch elements 126 of this disclosure preferably comprise an
aqueous solution containing starch, chalk or CaCO.sub.3, and an
anti-wrinkling agent. While many types of starch are contemplated,
tapioca starch is presently preferred for the starch component of
the layers of add-on material. A suitable commercially available
starch is FLO-MAX8.RTM. available from National Starch, LLC (now
Ingredion).
[0128] Many types of calcium carbonate particles are contemplated
as falling within the spirit and scope of this disclosure.
Presently, however, calcium carbonate available from Solvay
Chemicals, Inc., as SOCAL 31 is a suitable commercially available
calcium carbonate. SOCAL 31 is an ultrafine, precipitated form of
calcium carbonate having an average particle size of about 70 nm
(nanometers). Larger particles of calcium carbonate have been
observed to not function as well in this application when compared
to the ultrafine, precipitated form of calcium carbonate, due at
least in part to the tendency of larger particles to precipitate
from solution more quickly and due at least in part to the need for
greater quantities to attain the beneficial characteristics
discussed herein.
[0129] The film-forming compound can include one or more occluding
agents such as starch, alginate, cellulose or gum and may also
include calcium carbonate as a filler. Where starch is the
film-forming compound, a concentration of about 21% may be
advantageous. The film-forming composition may be applied to the
base web of the wrapper using gravure printing, digital printing,
coating or spraying using a template, or any other suitable
technique.
[0130] Uncoated areas of the base web preferably do not comprise
and are essentially free of any permeability reducing add-on
material.
[0131] The manufacture of base web 140 usually will include the
production of a roll of base web of several feet across (usually
about 3 feet across or in transverse dimension). The base web is
then drawn through a printing press or the like and rewound to
produce a roll of patterned paper, which is then slit into bobbins.
Printing operations are preferably conducted on the rolls, but
could be conducted after slitting. Preferably, the bobbins
themselves will have a transverse dimension equivalent to the width
needed to make tobacco rods 122 or an integral number of such
widths (e.g., 1, 2, or 4 of such widths). The bobbins are adapted
for use with typical cigarette making machinery. The wrapper
preferably has a dimension in cross-direction that takes into
account the nominal circumference of the tobacco rod and an
overlapping seam. As a result, when the wrapper is slit, the
smoking article formed therefrom always has a longitudinal seam
with an exact overlap.
[0132] The base web advances or passes through a first gravure
printing station where the first layer of each patch element is
printed on the paper. The printing process may be applied to the
"felt side" or the "wire side" of the base web, or both.
[0133] When an aqueous starch solution is being used as the add-on
materials, its preparation for application before and at the
printing press is preferably such that the add-on solution is
maintained at or about 120.degree. F. to about 140.degree. F., as
taught in U.S. patent application Ser. No. 13/324,747, filed Dec.
13, 2011.
[0134] Two illustrative examples for the geometric characteristics
of the patch element have been found to be desirable. In a first
arrangement, the patch elements may have a longitudinal length of
about 7 mm, a circumferential dimension of about 8.25 mm. In a
second arrangement, the patch elements may have a longitudinal
length of about 8 mm, and a circumferential dimension of about 8.25
mm.
Printing Apparatus
[0135] Referring now to FIG. 12, a preferred printing apparatus
includes a dispensing reel 601, a collection reel 608, an engraved
printing cylinder (gravure roller) 610, an impression cylinder 612,
an optional backing roller 614, a nip 616 defined between the
cylinder 610 and 612, a reservoir of add-on material 618, a pump
620 operative to pump add-on material from the reservoir 618, a
heat exchanger 622, an applicator 624, a bath 626, a collector 627,
a drain 628, a doctor blade 630, and an idler roller 634.
[0136] The impression cylinder 612 is mounted for counter-rotation
on an axis parallel to the axis of the printing cylinder (or
gravure roller) 610. In some applications, the impression cylinder
includes a nonmetallic resilient surface. The impression cylinder
is positioned between the roller and an optional backing roller
614, which is also mounted for rotation on an axis parallel to the
axis of gravure the roller 610 and which counter-rotates relative
to the impression cylinder. One of the functions provided by the
optional backing roller 614 is stiffening the central portions of
the impression cylinder so that the uniform printing pressure is
obtained between the gravure roller 610 and the impression cylinder
612. The gravure roller 610 and the impression cylinder 612
cooperate to define a nip 616 through which the base web is drawn
during the printing process. The nip 616 is sized to pinch the base
web as it moves between the gravure cylinder 610 and the impression
cylinder 612. The nip pressure 612 on the base web ensures the
correct transfer of the add-on material from the gravure roller 610
to the paper base web 140.
[0137] In a preferred embodiment, the reservoir 628 contains the
occlusive composition (add-on material), preferably an aqueous
starch solution as discussed above for forming patch elements 126
on the base web 140. The reservoir communicates with a suitable
pump 610 which is capable of handling the viscous occlusive
composition. The occlusive composition may then flow to a suitable
heat exchanger 622 where the temperature of the occlusive
composition is elevated so that it lies in the range of about
40.degree. to about 90.degree. C. (about 120.degree. F. to about
140.degree. F.) so that the viscosity of the occlusive composition
is adjusted to a level which is suitable for gravure printing and
for maintain desired conditions of the starch solution. As
discussed above, gravure printing usually requires a viscosity of
less than about 200 cP. Preferably, the temperature of the
occlusive composition is selected so that the viscosity is less
than about 100 cP. For example, the occlusive composition may have
a viscosity of about 10-40 cP at about 120.degree. F.
[0138] While a separate heat exchanger 622 is disclosed, it may be
desirable to provide thermal conditioning of the occlusive
composition in the reservoir 618 itself. For example, heating
elements and stirring apparatus may be included in the reservoir
618 to maintain the elevated temperature for the occlusive
composition. Placement of the thermal conditioning in the reservoir
has the advantage of making pump selection and operating
requirements simpler since the pump need not handle the occlusive
composition at the higher viscosity associated with lower
temperatures because the occlusive composition would already be
heated and, therefore, at the lower viscosity. Whether thermal
conditioning occurs in the reservoir or in a separate heat
exchanger, it is important that the thermal conditioning step occur
at a controlled temperature selected to avoid scorching the
occlusive composition. Scorching can cause discoloration of the
occlusive composition, and can affect the occlusive characteristics
of the composition.
[0139] Additionally, it is important to maintain an aqueous starch
solution at or about the range of about 120.degree. F. to
140.degree. F. prior to and during printing operations. Aqueous
starch solutions tend to degrade irreversibly if allowed to drop
below those temperatures.
[0140] Regardless of where the thermal conditioning step occurs,
the heated occlusive composition is preferably delivered to a
suitable applicator 624 that spreads the occlusive composition
across the width of the gravure cylinder. That spreading step may
be effected by pouring or spraying the occlusive composition onto
the gravure cylinder, or by delivering the liquid occlusive
composition to a collector 627 to establish a bath 626 of occlusive
composition in contact with a lower portion of the gravure cylinder
610. The gravure cylinder 610 may be heated to prevent premature
cooling of the composition.
[0141] Generally, the collector 627 extends partially about the
gravure roller to a height sufficient to collect the bath, but to a
height well below the top of the gravure cylinder 610. When the
bath reaches the top of the collector, occlusive composition can
flow through a drain 628 at the bottom of the apparatus back into
the reservoir. Thus, the occlusive composition circulates through
the printing station and can be maintained at suitable printing
viscosity by the thermal conditioning apparatus discussed
above.
Printing Cylinder
[0142] Referring now to FIG. 13, the preferred embodiment includes
an engraved printing cylinder (print roller) 610 having a plurality
of engraved regions 611, 611' in spaced-apart relation about the
circumference of the cylinder 610 corresponding to the desired
width "w" of the patch elements and the desired spacing "s" between
bands or rows as indicated by arrows "w" and "s" respectively, in
FIG. 13. The details of the engraved regions 611, 611' and the
printed rows 131, 131' have been omitted in FIGS. 13 and 14,
respectively, but the omitted details would correspond with those
appearing as printed rows 131, 131' in FIG. 14. Preferably the
engraved regions 611 are each slightly angulated in the form of a
chevron. The angle "A" at the tip 901 of the chevron is greater
than about 170 degrees. Such arrangement helps to further relieve
stress in the paper base web 140 upon application of the add-on
material, by spreading any puckering or wrinkling in opposing
directions on the left and right halves of the web along the
machine direction. It is envisioned that the engraved regions 611
might be instead arranged linearly without any chevron.
[0143] Preferably, the circumference of the roller is determined
such that it is an integer multiple of the sum of the nominal
distance between patch elements plus the patch element width. Thus,
for each revolution of the roller, that predetermined integer
number of patch elements is printed on the base web 140.
[0144] Printing consistency and efficiency is further enhanced by
elevating nip-pressure at the press. In a preferred embodiment, a
nip pressure was increased by approximately 10 to 15%, e.g., from
the normally applied pressure for the genre of printing
operation.
[0145] In the preferred embodiment, as shown in FIG. 14, each web
140 is printed with multiple rows 131 of patch elements 126 along
the length thereof. Preferably, the patch elements 126 are printed
in a chevron pattern on the base web (prior to slitting) such that
the apex 700 in the leading edge of each patch element 126 (FIG. 1)
is essentially transversely disposed of the outer points 710, 710'
(FIG. 14) on the trailing edge 148 (FIG. 1) of the preceding patch
element 126. In other words, the apex 700 (FIG. 14) and the outer
points 710, 710' essentially lie along an imaginary transverse line
702. It is envisioned that the angle at the apex 700 may be
adjusted to re-establish the aforementioned relationship if the
roll width is increased or decreased. Preferably, the apex angle
lies in the range of about 0.5.degree. to about 5.degree.. In the
alternative, the apex 700 may be established slightly ahead in a
machine direction of outer points 710, 710' of an adjacent patch
element 126.
[0146] The etched regions 611, 611' (FIG. 13) of the gravure roller
610 are configured and mutually arranged correspondingly. This
chevron shape and relationship helps avoid excessive waviness in
the web as a result of printing operations so that rewinding the
printed web and the slitting the web into bobbins may be conducted
without unacceptable occurrences of creases and tears. More
particularly, it is to be noted that along any transverse region
(or imaginary line) across the entire base web 140 after
application of the add-on composition, the transverse region will
include portions of the base web 140 that are not treated with
add-on material as well as portions that are treated with add-on
material. In contrast, without the chevrons (i.e., the patch
elements are arranged straight across the web), the shrinking
effect of the aqueous add-on material during drying is localized at
the location of the bands such that some transverse regions of the
web is subject to all the shrinking effect and some adjacent
transverse regions are not, which circumstance is known to
exacerbate waviness, which in turn leads to creasing and tears in
the web during rewinding and slitting.
[0147] With the chevrons (FIG. 14) the shrinking effect of the
add-on composition is distributed with a longitudinal component and
no longer does any thin, imaginary transverse region bear the
entirety of an application of add-on material. Consequently,
tendencies for creasing and tearing are abated. Accordingly, when
the add-on material is dried, the related transverse web shrinkage
is not localized in the printed (i.e., patch) areas, rather that
shrinkage rate gradually increases from a minimum value at the
leading at the apex 700 to the trailing edge apex 709 at the apex,
and remains substantially constant until the leading edge 146 (FIG.
1) of the band (the respective row 131) reaches the lateral edge of
the band (FIG. 14). From that location, the shrinkage decreases
until the trailing edge of the band where the minimum shrinkage
value exists. Thus, rather than step-wise shrinkage discontinuity,
the chevron printing design gives gradual shrinkage variation and
results in reduced waviness compared to prior techniques which used
parallel bands disposed perpendicularly across the base web.
[0148] Still referring to FIG. 14, once the base web 140 has been
printed with the chevron shaped rows 131 of patch element 126, the
base web is rolled and then slit longitudinally into a plurality of
parallel ribbons that are wound into bobbins. Typically the base
web may have a transverse width of about 50 inches, while
individual ribbons may have a transverse width of about 26 to 28 mm
or multiples thereof with a length of material on the order of
6,000 meters. Accordingly, the base web 140 of about 50 inch width
generates about 45 to about 50 ribbons or bobbins. Each individual
ribbon is collected by tightly winding it on a corresponding
bobbin, where each bobbin may have a length of material on the
order of 6,000 meters. The bobbins may then be used in conventional
cigarette making machinery in combination with tobacco material to
form a tobacco rod. The tobacco rods are then severed at
predetermined lengths, such that filters can be attached with
tipping paper to form finished cigarettes or smoking articles.
EXAMPLES
[0149] In a first example of a preferred embodiment, bobbins of 33
CORESTA patch wrapper were constructed with each patch element 126
being approximately 8 mm in width and approximately 8.25 mm in
cross measure, with an approximately 8.45 mm band spacing (between
adjacent rows 131) and an approximately 5.25 mm circumferential
spacing or gap (corresponding to designation 166 in FIG. 2) between
the patch elements 126. The add-on solution comprised water,
starch, calcium carbonate and 1,2 propylene glycol. The add-on
material was applied in a single pass gravure printing operation
utilizing chevron and solution preparation and thermal maintenance
as taught herein. The target diffusivity value was zero at the
patch elements and row sets 129 comprised four rows 131. Cigarettes
were constructed with the wrappers and tested for IP and SE
performance, with the results of an overall average IP of 7.7% and
an overall average SE value of 31%. Such is a significant and
surprisingly low SE value coupled with acceptable IP performance. A
second test resulted an overall average IP of 21.9% and an overall
average SE value of 23.6%.
[0150] In a second example of a preferred embodiment, bobbins of 33
CORESTA patch wrapper were constructed with each patch element 126
being approximately 7 mm in width and approximately 8.25 mm in
cross measure, with an approximately 9.45 mm band spacing (between
adjacent rows 131) and an approximately 5.25 mm circumferential
spacing or gap (corresponding to designation 166 in FIG. 2) between
the patch elements 126. The add-on solution comprised water,
starch, calcium carbonate and 1,2 propylene glycol. The add-on
material was applied in a single pass gravure printing operation
utilizing chevron and solution preparation and thermal maintenance
as taught herein. The target diffusivity value was zero at the
patch elements and row sets comprised four rows. Cigarettes were
constructed with the wrappers and tested for IP and SE performance,
with the results of an overall average IP of 13.4% and an overall
average SE value of 23.6%. Such is a significant and surprisingly
low SE value coupled with acceptable IP performance. A second test
resulted an overall average IP of 28.1% and an overall average SE
value of 21.7%.
[0151] It will now be apparent to those skilled in the art that
this specification describes a new, useful, and nonobvious smoking
article. It will also be apparent to those skilled in the art that
numerous modifications, variations, substitutes, and equivalents
exist for various aspects of the smoking article that have been
described in the detailed description above. Accordingly, it is
expressly intended that all such modifications, variations,
substitutions, and equivalents that fall within the spirit and
scope of the invention, as defined by the appended claims, be
embraced thereby.
* * * * *