U.S. patent application number 14/176423 was filed with the patent office on 2014-06-05 for gravure-printed, banded cigarette paper.
This patent application is currently assigned to PHILIP MORRIS USA, INC.. The applicant listed for this patent is PHILIP MORRIS USA, INC.. Invention is credited to Ping Li, Tracy L. Madison, Don E. Miser, Joe Yousef Mohajer, Tony A. Phan, Yezdi B. Pithawalla, Firooz Rasouli, TIMOTHY S. SHERWOOD, John R. Tilley, Bruce E. Waymack.
Application Number | 20140150811 14/176423 |
Document ID | / |
Family ID | 37499709 |
Filed Date | 2014-06-05 |
United States Patent
Application |
20140150811 |
Kind Code |
A1 |
SHERWOOD; TIMOTHY S. ; et
al. |
June 5, 2014 |
GRAVURE-PRINTED, BANDED CIGARETTE PAPER
Abstract
A cigarette and cigarette paper have a plurality of multilayer
bands formed by printing a highly viscous aqueous film-forming
composition. After heating the composition to lower its viscosity,
the bands are applied to the cigarette paper by gravure printing
the composition. The composition is quenched and gelatinized by
contact with the cool cigarette paper reducing absorption of water
by the paper and reducing wrinkling, cockling, and waviness.
Multiple gravure printed layers may be used to form the bands.
Inventors: |
SHERWOOD; TIMOTHY S.;
(Midlothian, VA) ; Rasouli; Firooz; (Midlothian,
VA) ; Li; Ping; (Glen Allen, VA) ; Miser; Don
E.; (Chesterfield, VA) ; Mohajer; Joe Yousef;
(Midlothian, VA) ; Waymack; Bruce E.; (Prince
George, VA) ; Phan; Tony A.; (Richmond, VA) ;
Madison; Tracy L.; (Richmond, VA) ; Tilley; John
R.; (Chesterfield, VA) ; Pithawalla; Yezdi B.;
(Midlothian, VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PHILIP MORRIS USA, INC. |
Richmond |
VA |
US |
|
|
Assignee: |
PHILIP MORRIS USA, INC.
Richmond
VA
|
Family ID: |
37499709 |
Appl. No.: |
14/176423 |
Filed: |
February 10, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11500918 |
Aug 9, 2006 |
8646463 |
|
|
14176423 |
|
|
|
|
60707964 |
Aug 15, 2005 |
|
|
|
Current U.S.
Class: |
131/331 ;
106/31.13; 131/365 |
Current CPC
Class: |
A24D 1/16 20130101; A24C
5/005 20130101; A24D 1/02 20130101; A24D 1/025 20130101 |
Class at
Publication: |
131/331 ;
131/365; 106/31.13 |
International
Class: |
A24D 1/02 20060101
A24D001/02; A24D 1/16 20060101 A24D001/16 |
Claims
1-15. (canceled)
16. A printing composition for cigarette paper comprising: water;
and a film-forming compound comprising 20 to 50% by weight; wherein
the printing composition has a viscosity less than about 100 cP at
a temperature in the range of 40.degree. to 90.degree. C., and a
viscosity exceeding about 200 cP at a temperature of about
23.degree. C.
17. The printing composition of claim 16, wherein the film-forming
compound is selected from the group consisting of starch, alginate,
carrageenan, guar gum, pectin, calcium carbonate, and citrates.
18. The printing composition of claim 16, wherein the film-forming
compound is starch.
19. The printing composition of claim 17, wherein the film-forming
compound is an oxidized starch.
20. The printing composition of claim 17, wherein the film-forming
compound is alginate.
21. A cigarette wrapper paper comprising: a paper web having a
porosity exceeding about 20 Coresta units; a plurality of bands on
the web, the bands being generally parallel and spaced from one
another by a nominal distance exceeding the width of the bands but
less than the nominal length of a cigarette tobacco rod, each band
including a gelatinized film-forming composition that gels when
cooled to room temperature and which comprises at least two layers,
and the porosity through the band and underlying paper being in the
range of 0 to 15 Coresta units; a first layer of said at least two
layers being directly on the web consisting of a gelled
film-forming composition selected from the group consisting of
starch, alginate, carrageen, guar gum, pectin, calcium carbonate,
and citrates, the gelled film-forming composition having been
printed directly onto the web as a viscous, aqueous solution in a
heated condition and cooled upon contact with the surface of the
web.
22-23. (canceled)
24. The cigarette wrapper paper of claim 21, wherein the layers of
each band have a composite coat weight in the range of 0.5 to 15
gsm.
25. The cigarette wrapper paper of claim 24, wherein the composite
coat weight is about 5 gsm.
26. The cigarette wrapper paper of claim 21, wherein a first layer
contacts the paper, and a second layer is on the first layer.
27. The cigarette wrapper paper of claim 26, wherein a third layer
is on the second layer.
28. A cigarette comprising: a tobacco rod constructed of the
wrapper as claimed in claim 21.
29-39. (canceled)
40. A cigarette wrapper comprising: a base web; and a plurality of
bands disposed at spaced locations along said base web, said bands
including at least one application of a gelled film-forming agent
that is in a condition of having been printed upon said spaced
locations while in a fluid heated state, said agent having gelled
upon contact with the base web.
41. A smoking article comprising a tobacco rod and optionally a
filter, said tobacco rod including the cigarette wrapper of claim
40.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C.
.sctn.119(e) to U.S. provisional Application No. 60/707,964, filed
on Aug. 15, 2005, the entire content of which is incorporated
herein by reference.
FIELD OF THE DISCLOSURE
[0002] This disclosure relates generally to banded paper for use in
manufacturing cigarettes. More particularly, it concerns print
banded paper made with a gravure printing process using an aqueous
composition of highly viscous material.
SUMMARY
[0003] A cigarette according to one embodiment includes cigarette
paper with a plurality of bands, each of which is effective to
substantially reduce permeability of cigarette paper in its
vicinity to control ignition propensity and inhibit unattended
burning when the cigarette is left on a substrate. Each band may be
formed by one or more layers, each of which may be applied by
gravure printing. Moreover, the first layer (or layers) of each
band is (or are) preferably formed using an aqueous film-forming
composition having a viscosity not well-suited for gravure
printing. The subsequent layer (or layers) of each band is (are)
preferably formed by using the same aqueous film forming
composition or other aqueous compositions containing fillers, burn
inhibitors, burn promoters, flavors and the like.
[0004] During the gravure printing steps, the viscous film-forming
composition is heated to a temperature where its viscosity lies
within the range of viscosities suitable for gravure printing. When
the heated film-forming composition is applied to the cigarette
paper, the film-forming composition is cooled or quenched and may
be gelatinized. Thus, a portion of the free water in the
film-forming composition becomes bound and unavailable to soak or
migrate into underlying fibers of the cigarette paper. That binding
of free water inhibits formation of waviness, cockling, and/or
wrinkling in the cigarette paper. Total coat weight for the band
preferably lies in the range of 0.5 to 15 grams per square meter
("gsm"), and most preferably about 2 gsm. Permeability of the
cigarette paper normally exceeds 20 Coresta units. However,
permeability through the bands and the underlying cigarette paper
preferably lies in the range of 0 to 15 Coresta units. The
reduction in permeability preferably restricts air flow needed to
support combustion of the cigarette coal in the vicinity of the
band.
[0005] In a preferred embodiment, the film-forming composition used
for printing comprises water and about 20% to about 50%
film-forming compound selected from the group consisting of
alginate, carrageenan, guar gum, pectin, calcium carbonate, and
citrates. At higher concentrations of the film-forming compound in
the composition, the composition may experience gelatinization when
its temperature is rapidly reduced. Thus, the binding of free water
into the printed band may occur.
[0006] According to a preferred method of manufacturing cigarette
paper with bands, the cigarette paper advances to a first printing
station. At that first printing station, the film-forming
composition is heated so that its viscosity is decreased to a
predetermined value useful for gravure printing. The heated
film-forming composition is applied to the patterned surface of a
rotating gravure cylinder. The rotating gravure cylinder may be
heated to prevent premature cooling of the composition. The
rotating gravure cylinder cooperates with a parallel impression
roller to define a nip through which the cigarette paper advances.
As the gravure cylinder rotates, its patterned surface contacts the
cigarette paper and applies the first layer of the bands to the
cigarette paper.
[0007] The film-forming composition is believed to cool and gel on
contact with the cigarette paper. Thus, the water content of the
film-forming composition is not appreciably absorbed into the
cigarette paper and planarity of the cigarette paper is
preserved.
[0008] After the first layer is applied to the cigarette paper it
is allowed to dry thereon. The paper may then advance to a second
gravure printing station where a second layer may be applied to the
first layer of each band. Preferably, this optional second layer is
coextensive with the first layer in both width and length; however,
the second layer may be thicker than the first layer. The
film-forming composition of the second layer gels on the cooler
first layer--and free water does not get absorbed by the paper.
[0009] Optional third and successive layers may be applied on top
of the second layer, and on underlying layers in the same way,
preferably using the same film-forming composition, or different
compositions containing fillers, burn inhibitors, burn promoters,
flavors, and the like, as may be desired.
[0010] Another embodiment provides a process of applying only the
first layer utilizing a heated gelatinizable film-forming solution,
with one or more additional layers comprising a different add-on
material such as a starch that is printable in an unheated
state.
[0011] The resulting banded cigarette is collected on a reel that
is subsequently cut into bobbins and used as cigarette paper to
make cigarettes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The accompanying drawings depict a print banded paper where
the bands are printed in multiple successive layers and apparatus
for making such paper. In the accompanying drawings, like reference
numerals are applied to like elements.
[0013] FIG. 1 is a perspective view of a cigarette made with paper
having multilayer bands.
[0014] FIG. 2 is a cross-sectional view taken along the line 2-2 of
FIG. 1.
[0015] FIG. 3 is an enlarged scale portion of FIG. 2 circumscribed
by the line 3 with the thickness of the multilayer band exaggerated
for purposes of clarity.
[0016] FIG. 4 is a schematic view of apparatus for preparing
multi-layer print banded paper.
DETAILED DESCRIPTION
[0017] In accordance with this disclosure (see FIG. 1), a cigarette
20 includes a tobacco rod including cut filler, covered by
cigarette paper 22. One end of the cigarette 20 may include a
suitable filter 24 surrounded by suitable filter tipping paper
26.
[0018] The cigarette paper 22 (see FIG. 2) surrounds a column of
tobacco 28 made from cut filler tobacco. The tobacco rod 28 has a
nominal length measured along the longitudinal axis 29 which
nominal length is the difference between the overall length and the
length of the filter 24.
[0019] Conventional cigarette paper is permeable, with the
permeability commonly designated 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). Conventional cigarette papers also have
well-known basis weights, measured in grams per square meter,
abbreviated as "gsm". The permeability and basis weight for typical
cigarette 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 25 46 25 60 26
[0020] For purposes of this disclosure, unbanded regions of a
preferred cigarette paper have a permeability of at least 20
Coresta units. Most preferably, the cigarette paper has a
permeability of about 33 to about 46 Coresta and a basis weight of
about 25 gsm.
[0021] To regulate the ignition propensity of the cigarette and to
inhibit unattended burning of the cigarette, the cigarette paper 22
has a plurality of bands 30 spaced axially along the tobacco rod
28. Permeability of the cigarette paper 22 through the area covered
by the bands 30 preferably lies in the range of 0 to about 15
Coresta units. Typically, at least two bands 30 are disposed along
the tobacco rod 28. Adjacent bands 30 are spaced from one another
along the tobacco rod 28 by a nominal distance which preferably
exceeds the width of the bands 30. However, that nominal distance
is less than the nominal length of the tobacco rod 28. Each band 30
extends circumferentially around the tobacco rod 28 preferably on
the inside of the cigarette paper 22. Accordingly, the presence of
the bands 30 is essentially invisible from the outside of the
cigarette.
[0022] Each band 30 (see FIG. 3) may comprise a plurality of
layers. Two or three layers 32, 34, 36 may be provided. The first
layer 32 rests directly on the inside (or alternatively, the
outside) of the cigarette paper 22 and has a corresponding
first-layer thickness. The optional second layer 34 lies on the
first layer 32 and, preferably extends coextensively with the first
layer both in width and length. The second layer 34 has a
corresponding second-layer thickness. The optional third layer 36,
lies on the second layer and, preferably extends coextensively with
the second layer both in width and length. The third layer 36 has a
third-layer thickness. Thicknesses of the various layers 32, 34, 36
are measured perpendicularly to the surface of the cigarette paper
22.
[0023] The first layer 32 is applied to the cigarette paper 22 to
seal the paper surface from water penetration and thereby minimize
resultant distortion of the cigarette paper 22 by way of wrinkling,
cockling, and waviness. Such distortions can occur when paper
fibers absorb water, then stretch and warp, and fail to return to
their original position and state in the paper web. The first-layer
thickness is selected such that aqueous solvent does not penetrate
deeply into the paper 22. Thickness of the layers 32, 34, 36 is a
direct function of coat weight. Accordingly, relative thicknesses
of the layers correspond to relative coat weights, and vice
versa.
[0024] In accordance a preferred embodiment, each band 30 is
printed on the cigarette paper 22 by sequential gravure printing
steps using an aqueous film-forming composition or other aqueous
compositions as desired. The film-forming composition preferably
includes water and a high concentration of a film-forming compound.
For example, the film-forming compound preferably comprises about
20% to about 50%, by weight, of the film-forming composition. At
room temperature (about 23.degree. C.), the high-solid-content
film-forming composition has a viscosity exceeding about 200
centipoise (cP) and is unsuitable for gravure printing; however, at
a temperature in the range of about 40.degree. to about 90.degree.
C., the viscosity of the film-forming composition is decreased
sufficiently for use as a gravure printing composition. For gravure
printing, the upper limit of suitable viscosity is about 200 cP.
Most preferably, the film-forming composition has a viscosity of
about 100 cP at a temperature in the range of 40.degree. C. to
90.degree. C. so that the composition can be quenched on contact
with the paper after gravure printing at that temperature. The
viscosity of the composition at room temperature is also important.
The high viscosity at room temperature is needed so that the
film-forming composition gels at room temperature.
[0025] The film-forming compound used in the film-forming
composition may be selected from the group consisting of alginate,
carrageenan, guar gum, pectin, calcium carbonate, and citrates.
Preferably, the film-forming compound is selected from the group
consisting of an oxidized starch, such as tapioca.
[0026] Preferably, the bands 30 are applied to the cigarette paper
22 using a sequential gravure printing process (see FIG. 4).
Gravure printing operations are capable of precise registry of
successive printing operations. Accordingly, gravure printing can
be used to effectively print not only the first layer 32 of the
bands 30, but also the second layer 34 substantially coextensive
with the first layer, and the third layer 36 substantially
coextensive with the second layer.
[0027] With the first layer 32 sealing the surface of the cigarette
paper 22, the optional second layer can be applied with a heavier
coat weight, i.e., coat thickness. If desired, the second layer 34
may be thicker than the first layer 32 by a factor of at least
about 1.5 times the first-layer thickness, or at least a 50%
increase in coat weight. Moreover, the optional third layer 36 may
be thicker than the second layer 34 and may also be thicker than
the first layer 32 by a factor of at least about 2.5 times the
first-layer thickness--i.e., an increase of at least about 150% in
coat weight.
[0028] The gravure printing process can be used immediately
following paper manufacture, i.e., at the end of the paper making
machine. Alternatively, the gravure printing process can be used in
connection with reels carrying the cigarette paper onto which the
bands are to be printed. For example, a reel 40 of cigarette paper
having a selected permeability and a selected basis weight is
mounted so that the cigarette paper 22 can be unspooled from the
reel 40 as a continuous paper web.
[0029] The web of cigarette paper 22 advances or passes through a
first gravure printing station 42 where the base layer 32 of each
band 30 is printed on the paper 22. The printing process may be
applied to the felt side or the wire side of the paper, or both.
Next, the cigarette paper 22 passes through a second gravure
printing station 44 where the second layer 34 of each band 30 is
printed on the corresponding base layer 32. The cigarette paper 22
then passes through a third gravure printing station 46 where the
third layer 36 of each band 30 is printed on the corresponding
second layer 34. Additional layers are applied in a similar manner
as described. Finally, the cigarette paper 22 with the printed
bands is wound up on a collection reel 48. The collection reel 48
is then slit into bobbins. The bobbins are used for wrapping
tobacco rods during manufacture of cigarettes in an otherwise
conventional way.
[0030] The apparatus at each of the three gravure printing stations
42, 44, 46 is essentially the same in its material aspects.
Accordingly, it will suffice to describe one of the gravure
printing stations in detail, it being understood that the other
gravure printing stations have common features, unless otherwise
noted. Thus, features of the first gravure printing station 42 will
use reference numerals with the suffix "a". Corresponding features
of the second gravure printing station 44 will use the same
reference numeral but will use the suffix "b". Likewise,
corresponding features of the third gravure printing station 46
will use the same reference numeral but will use the suffix
"c".
[0031] At the first gravure printing station 42, the apparatus
includes a gravure cylinder or roller 50a generally mounted for
rotation around a horizontal axis. The generally cylindrical
surface of the roller 50a is patterned in a suitable process to
define a negative of the first layer 32 of bands 30. Conventional
engraving, chemical engraving, electronic engraving, and photo
etching can be used to pattern the surface of the gravure cylinder.
The circumference of the roller 50a is determined such that it is
an integral multiple of the sum of the nominal distance between
bands plus the band width. Thus, for each revolution of the roller
50a, that integral number of first layers of the bands is printed
on the cigarette paper.
[0032] An impression cylinder 52a is mounted for counter-rotation
on an axis parallel to the axis of the roller 50a. In some
applications, the impression cylinder 52a includes a nonmetallic
resilient surface. The impression cylinder 52a is positioned
between the roller 50a and a backing roller 54a, which is also
mounted for rotation on an axis parallel to the axis of the roller
50a and which counter-rotates relative to the impression cylinder
52a. One of the functions provided by the backing roller 54a is
stiffening the central portions of the impression cylinder 52a so
that the uniform printing pressure is attained between the roller
50a and the impression cylinder 52a. The gravure cylinder or roller
50a and the impression cylinder 52a cooperate to define a nip 56a
through which the paper web 22 advances during the printing
process. That nip 56a is sized to pinch the paper web 22 as it
moves between the gravure cylinder 50a and the impression cylinder
52a. The nip pressure on the paper web is critical to ensure the
correct transfer of the composition from the cylinder to the
paper.
[0033] A reservoir 58a contains the film-forming composition
discussed above for forming bands on the cigarette paper. The
reservoir 58a communicates with a suitable pump 60a which is
capable of handling the viscous film-forming composition. The
film-forming composition may then flow to a suitable heat exchanger
62a where the temperature of the film-forming composition is
elevated so that it lies in the range of about 40.degree. to about
90.degree. C. so that the viscosity of the film-forming composition
is adjusted to a level which is suitable for gravure printing. As
discussed above, viscosity for gravure printing needs to be less
than about 200 cP. Preferably, the temperature of the film-forming
composition is selected so that the viscosity is less than about
100 cP.
[0034] While a separate heat exchanger 62a is disclosed, it may be
desirable to provide thermal conditioning of the film-forming
composition in the reservoir 58a itself. For example, heating
elements and stirring apparatus may be included in the reservoir
58a to maintain the elevated temperature for the film-forming
composition. Placement of the thermal conditioning in the reservoir
58a has the advantage of making pump selection and operating
requirements simpler since the pump 60a need not handle the
film-forming composition at the higher viscosity associated with
lower temperatures because the film-forming composition would
already be heated and, therefore, at the lower viscosity. Whether
thermal conditioning occurs in the reservoir 58a or in a separate
heat exchanger 62a, it is important that the thermal conditioning
step occur at a temperature selected to avoid scorching the
film-forming composition. Scorching can cause discoloration of the
film-forming composition, and can affect the film-forming
characteristics of the composition. Thus, scorching is to be
avoided while the film-forming composition is subjected to thermal
conditioning.
[0035] Regardless of where the thermal conditioning step occurs,
the heated film-forming composition is delivered to a suitable
applicator 64a that spreads the film-forming composition along the
length of the gravure cylinder 50a. That spreading step may be
effected by pouring or spraying the film-forming composition onto
the gravure cylinder 50a, or simply by delivering the liquid
film-forming composition to a bath 66a of film-forming composition
that collects at the bottom of the gravure cylinder 50a, between
the gravure cylinder 50a and a collector 67a. The cylinder may be
heated to prevent premature cooling of the composition.
[0036] Generally, the collector 67a extends vertically around the
gravure roller 50a to a height sufficient to collect the bath 66a,
but to a height well below the top of the gravure cylinder 50a.
When the bath 66a reaches the top of the collector 67a,
film-forming composition can flow through a drain 68a at the bottom
of the apparatus back into the reservoir 58a. Thus, the
film-forming composition circulates through the printing station
and can be maintained at suitable printing viscosity by the thermal
conditioning apparatus discussed above.
[0037] As the gravure cylinder 50a rotates through the applicator
64a and/or the bath 66a, the film-forming composition adheres to
the surface of the gravure cylinder 50a, including in the
impressions provided therein to define the bands. Further rotation
of the gravure cylinder 50a toward the nip 56a moves the cylinder
surface past a suitable doctor blade 70a. The doctor blade 70a
extends along the length of the gravure cylinder and is positioned
so that is wipes the surface of the gravure cylinder 50a. In this
way, those portions of the gravure cylinder 50a that define the
nominal spacing between adjacent bands is essentially wiped clean
of the film-forming composition, while engraved portions of the
gravure cylinder that define the bands themselves advance toward
the nip 56a full of the film-forming composition.
[0038] As the cigarette paper 22 and the surface of the gravure
cylinder 50a move through the nip 56a, the film-forming composition
is transferred to the surface of the cigarette paper 22. The linear
speed or velocity of the cigarette paper 22 matches the tangential
surface speed of both the gravure cylinder 50a and the impression
cylinder 52a as the cigarette paper 22 passes through the nip 56a.
In that way, slippage and/or smearing of the film-forming
composition on the cigarette paper 22 are avoided.
[0039] When the bands are printed on the cigarette paper 22 at the
first printing stations 42, the heated film-forming composition
encounters cigarette paper 22 at room temperature of about
23.degree. C.--which is considerably cooler than the temperature of
the film-forming composition--i.e., about 40.degree. to about
90.degree. C. Upon contact with the paper 22, the temperature of
the film-forming composition is quenched to the temperature of the
paper 22. That quenching occurs through several heat transfer
processes or mechanisms. The paper 22 has a sufficiently large
thermal mass when compared to the thickness and width of the first
layer of the band, that the film-forming material in the band
equilibrates to a temperature near to the temperature of the paper
rapidly, if not immediately. The temperature of air near the paper
22 and the gravure cylinder 50a is also well below the temperature
of the film-forming material on the surface of the gravure cylinder
50a so cooling to ambient air also occurs. In addition, movement of
the surface of the gravure cylinder 50a, as well as movement of the
cigarette paper 22 after printing, contributes to convective
cooling of the film-forming material.
[0040] The combined cooling effect of those heat transfer
mechanisms causes the film-forming material to gel on the surface
of the cigarette paper 22. That gelling of the first layer of the
band tends to bind water in the film-forming composition so that
the water does not penetrate deeply into, and possibly saturate,
the cigarette paper 22. As a result, fibers of the cigarette paper
22 typically are not wetted by water to such an extent that the
fibers warp and stretch in a way that leads to waviness, wrinkling,
and/or cockling in the cigarette paper 22. The impression cylinder
52a can optionally be cooled to further accelerate gelatinization
of the film-forming composition on the cigarette paper. Additional
techniques may be used to reduce water absorption. For example,
acceleration of solidification of the film forming material may be
effected by mixing alginate with a calcium sale, such as calcium
chloride, in situ or by exposure to ultraviolet light.
[0041] As the cigarette paper 22 leaves the first printing station
42, moisture in the film-forming composition is permitted to dry.
To this end, suitable arrangements (not shown) may be employed.
[0042] Cigarette paper with the first layer of the bands printed at
the first gravure printing station 42 then pass over an adjustment
cylinder 72b of the second gravure printing station 44. The gravure
cylinder 50b of the second printing station has a patterned surface
that is designed to print the second layer of the bands. The depth
of the pattern on the surface of the gravure cylinder 50b is
selected to be about 1.5 times the depth of the pattern on the
first gravure cylinder 50a. Preferably, the second layer of the
bands will be coextensive in width (in the direction of paper
movement) and coextensive in length (in the direction transverse to
paper movement) with the first layer of the band. The gravure
cylinder 50b of the second printing station 44 must therefore be
registered with the gravure cylinder 50a of the first printing
station 42. While various techniques for assuring that registration
are known to those skilled in the art, the adjustment cylinder 72b
can be used to assure correct registration. More particularly, the
length of the cigarette paper 22 between the nip 56a of the first
printing station 42 and the nip 56b of the second printing station
44 depends on the vertical position of the adjustment cylinder 72b.
By adjusting the position of the cylinder 72b, proper registration
between the first and second print stations 42, 44 can be achieved
and, if necessary, adjusted.
[0043] As the cigarette paper 22 moves from the second printing
station 44 to the third printing station 46, the film-forming
composition applied at the second printing station 44 has
sufficient time to dry. After passing over the adjustment roller
72c of the third printing station 46, the cigarette paper 22 enters
the nip 56c of the third printing station 46 where the third layer
of the bands is applied.
[0044] The gravure cylinder 50c of the third printing station 46
has a patterned surface that is designed to print the third layer
of the bands. The depth of the pattern on the surface of the
gravure cylinder 50c is selected to be about 2.5 times the depth of
the pattern on the first gravure cylinder 50a. Preferably, the
second layer of the bands will be coextensive in width (in the
direction of paper movement) and coextensive in length (in the
direction transverse to paper movement) with both the first layer
and the second layer of the band. The gravure cylinder 50c of the
third printing station 44 must therefore be registered with the
gravure cylinder 50b of the second printing station 44. As
described above, the adjustment cylinder 72c can provide that
registration function.
[0045] After leaving the third printing station 46, the third layer
of the band is allowed to dry before encountering the idler roller
74. Additional printing stations (not shown) may be used, as
desired. The cigarette paper 22 with the multi-layer bands is then
collected on the collection reel 48.
[0046] The bands 30 are applied with a low coat weight. For
example, the total coat weight may lie in the range of about 0.5 to
about 15 gsm for the multiple layers of the bands 30. Preferably,
the coat weight may be about 2 gsm. With those coat weights, the
thickness of the multilayer bands 30 (FIG. 3) preferably is less
than about 20% of the thickness of the cigarette paper, and may be
less than 5% of the thickness of the cigarette paper. The thickness
of the first layer 32 of the band 30 applied in the first gravure
printing station, preferably is less than 4% of the cigarette paper
thickness, and may be less than 1% of the cigarette paper
thickness. Thus, it is seen that the thickness of the first layer
is small in relation to the thickness of the underlying cigarette
paper.
[0047] By heating the film-forming composition, gelatinization of
the film-forming compound upon cooling is enhanced. Accordingly,
when the film-forming composition is quenched at the surface of the
cigarette paper 22, a gel forms. Formation of the gel binds some of
the water from the composition and prevents that water from
entering fibers of the cigarette paper. This effect further reduces
the possibility that printing of the aqueous film-forming
composition will lead to waviness or other imperfections in the
resulting banded cigarette paper.
[0048] While the process for making banded cigarette paper
according to this disclosure will be apparent to those skilled in
the art from the foregoing description, the process will
nevertheless be summarized below.
[0049] Cigarette paper mounted on a reel 40 (see FIG. 4), advances
as a paper web 22 to a first printing station 42. At that first
printing station 42, gravure printing apparatus prints a first
layer of the film-forming composition on the cigarette paper 22.
That printing step includes heating the film-forming composition to
temperature where viscosity of the film-forming composition drops
below the threshold for gravure printing while avoiding
temperatures that could scorch the film-forming material. The
heating step reduces viscosity of the film-forming material below
about 200 cP, and most preferably to around 100 cP or less.
[0050] The heated film-forming composition is applied to the
patterned surface of a rotating gravure cylinder 50a. Application
of the composition to the patterned surface may be accomplished by
pouring or spraying the composition on the patterned surface or by
moving the patterned surface through a bath of heated composition.
Regardless of the application technique used, excess composition is
wiped from the patterned surface of the gravure cylinder 50a with a
doctor blade.
[0051] Thereafter, the rotating surface of the gravure roller 50a
contacts the advancing cigarette paper as it moves through the nip
56a. There, the film-forming composition transfers from the
patterned surface of the gravure cylinder 50a to the cigarette
paper 22 and is quenched by contact with the cigarette paper
surface. Gelatinization of the film-forming composition on the
surface of the cigarette paper 22 binds at least a portion of the
free water in the film-forming composition so that the water
content of the composition does not disrupt planarity of the
cigarette paper and cause cockling, waviness, and/or wrinkling.
[0052] The first layer 32 of the bands 30 then dries as the
cigarette paper 22 continues to advance through the printing
operations. When the first layer 32 has dried, it enters a second
gravure printing station 44 where a second layer of the bands 34 is
applied. The gravure printing at the second station 44 and the
film-forming composition used are processed in the same way as
described above in connection with the first printing station 42.
However, the patterned surface of the second gravure cylinder 50b
is prepared so that the thickness of bands it applies exceeds the
thickness of the first layer. The second layer of each band is
printed on the first layer so as to be coextensive with the first
layer, both in width and in length.
[0053] After the second layer of the bands dries, the cigarette
paper advances to the third gravure printing station 46 where a
third layer may be printed on the second layer in the manner just
described. At the third station 46, the patterned surface of the
gravure cylinder is prepared so that the thickness of bands it
applies exceeds the thickness of the second layer.
[0054] When all the desired layers have been printed on the
cigarette paper 22, the paper is wound on a collection reel 48 for
subsequent use in manufacture of cigarettes.
[0055] The terms and phases 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. Where the term "about"
is used in relation to a number, it is intended that such number
has a tolerance of plus or minus 5%. Similarly, such terms 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.
[0056] It will now be apparent to those skilled in the art that
this specification describes a new, useful, and nonobvious
progressive multi-pass print banded paper. It will also be apparent
to those skilled in the art that numerous modifications,
variations, substitutes, and equivalents exist for various aspects
of the invention 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.
* * * * *