U.S. patent application number 10/806221 was filed with the patent office on 2004-09-16 for sheet tobacco, and process and system for manufacturing the same.
This patent application is currently assigned to Japan Tobacco. Invention is credited to Hagiwara, Kouichi, Iijima, Toshiki, Kan, Katsuhiko, Kawai, Kiyotaka, Miyakoshi, Yoshisato, Nakanishi, Yukio, Narita, Hiroaki, Ota, Akinori, Shimono, Naohiko.
Application Number | 20040177857 10/806221 |
Document ID | / |
Family ID | 15660683 |
Filed Date | 2004-09-16 |
United States Patent
Application |
20040177857 |
Kind Code |
A1 |
Nakanishi, Yukio ; et
al. |
September 16, 2004 |
Sheet tobacco, and process and system for manufacturing the
same
Abstract
Sheet tobacco according to the present invention includes a
carrier sheet made of nonwoven plant fibers, and a tobacco powder
layer formed on the carrier sheet and containing a powder mixture
of tobacco lamina powder and binder powder. In a sheet tobacco
manufacturing process according to the present invention, a carrier
sheet of plant fibers is formed by a nonwoven fabric production
process, a tobacco powder layer is formed by spreading the powder
mixture on the carrier sheet, and a cover sheet of plant fibers is
optionally formed on the tobacco powder layer. Subsequently, the
carrier sheet, the tobacco powder layer and the optical cover sheet
are all together subjected to heating and pressing, thereby
producing sheet tobacco with a two- or three-layer structure. The
present invention also provides a manufacturing system for carrying
out the sheet tobacco manufacturing process.
Inventors: |
Nakanishi, Yukio; (Kanagawa,
JP) ; Ota, Akinori; (Kanagawa, JP) ; Kan,
Katsuhiko; (Tokyo, JP) ; Shimono, Naohiko;
(Ibaraki, JP) ; Kawai, Kiyotaka; (Shiga, JP)
; Miyakoshi, Yoshisato; (Ibaraki, JP) ; Narita,
Hiroaki; (Tokyo, JP) ; Iijima, Toshiki;
(Tokyo, JP) ; Hagiwara, Kouichi; (Shiga,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Japan Tobacco
Japan Vilene Company, Ltd.
|
Family ID: |
15660683 |
Appl. No.: |
10/806221 |
Filed: |
March 23, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10806221 |
Mar 23, 2004 |
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10000159 |
Dec 4, 2001 |
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6761175 |
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10000159 |
Dec 4, 2001 |
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PCT/JP00/03612 |
Jun 2, 2000 |
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Current U.S.
Class: |
131/370 |
Current CPC
Class: |
A24B 15/14 20130101;
A24B 3/14 20130101; B32B 37/24 20130101; B32B 2317/00 20130101;
B32B 37/12 20130101; A24B 15/16 20130101 |
Class at
Publication: |
131/370 |
International
Class: |
A24B 003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 4, 1999 |
JP |
11-157934 |
Claims
1. A sheet tobacco manufacturing process comprising: a preparing
step of preparing a carrier sheet of nonwoven plant fibers; a
forming step of spreading a tobacco powder material on said carrier
sheet to form a tobacco powder layer covering one side of said
carrier sheet; an adding step of adding a binder to said tobacco
powder layer during or after said forming step; and a binding step
of binding the tobacco powder material in said tobacco powder layer
as well as said tobacco powder layer and said carrier sheet to each
other by means of the binder.
2. The process according to claim 1, wherein said carrier sheet is
formed in said preparing step by a dry nonwoven fabric production
process, and said forming step is performed continuously following
the formation of said carrier sheet to form said tobacco powder
layer on the one side of said carrier sheet.
3. The process according to claim 1 or 2, further comprising an
intermediate step performed between said forming step and said
binding step, to form a cover sheet of nonwoven plant fibers
covering the other side of said tobacco powder layer.
4. The process according to claim 3, wherein said intermediate step
is performed following the formation of said tobacco powder layer,
to form said cover sheet by a dry nonwoven fabric production
process.
5. The process according to claim 1 or 4, wherein in said binding
step, the plant fibers of at least one of said carrier sheet and
said cover sheet are bound together by means of the binder.
6. The process according to claim 1, wherein in said adding step, a
binder of powder form is added during the formation of said tobacco
powder layer.
7. The process according to claim 6, wherein the binder contains
cornstarch.
8. The process according to claim 6 or 7, further comprising an
infiltrating step performed prior to said binding step, to cause a
solvent for the binder to infiltrate into said tobacco powder layer
admixed with the binder as well as into said carrier sheet.
9. The process according to claim 8, wherein in said binding step,
said tobacco powder layer and said carrier sheet are pressed with
heat applied thereto.
10. The process according to claim 1, further comprising a step of
forming a tobacco particle layer between said carrier sheet and
said tobacco powder layer or between said tobacco powder layer and
said cover sheet, said tobacco particle layer containing particles
of tobacco stems and laminas.
11. A sheet tobacco manufacturing system comprising: an endless net
conveyor traveling in one direction; an upstream-side forming
device arranged at an upstream portion of said net conveyor, for
forming a carrier sheet of nonwoven plant fibers on said net
conveyor; a powder spreading device arranged on a downstream side
of said upstream-side forming device, for spreading a tobacco
powder material on the carrier sheet to form a tobacco powder layer
covering the carrier sheet; and a pressing device arranged on a
downstream side of said powder spreading device, for heating and
pressing the carrier sheet and the tobacco powder layer.
12. The system according to claim 11, further comprising a spraying
device arranged on an upstream side of said upstream-side forming
device, for wetting in advance said net conveyor with a
predetermined liquid.
13. The system according to claim 11 or 12, further comprising a
downstream-side forming device arranged between said powder
spreading device and said pressing machine, for forming a cover
sheet of nonwoven plant fibers covering the tobacco powder
layer.
14. The system according to claim 13, wherein said downstream-side
forming device includes a fiber spreading unit arranged above said
net conveyor for spreading plant fibers toward said net conveyor, a
mesh conveyor arranged between the fiber spreading unit and said
net conveyor, the mesh conveyor sucking thereon the plant fibers
spread from the fiber spreading unit to form a cover sheet and
transporting the cover sheet toward said net conveyor, and peeling
means for peeling the cover sheet from the mesh conveyor to allow
the cover sheet on the mesh conveyor to be transferred onto the
tobacco powder layer.
Description
[0001] This is a divisional application of U.S. application Ser.
No. 10/000,159, now allowed. This divisional application claims
priority to U.S. application Ser. No. 10/000,159 under 35 USC
.sctn.120. The disclosure of U.S. Ser. No. 10/000,159 in its
entirety is expressly incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to sheet tobacco used as a
sort of shredded filler for cigarettes or filter cigarettes, and a
process and system for manufacturing such sheet tobacco.
BACKGROUND ART
[0003] In general, sheet tobacco of this kind is produced by a
rolling process, a papermaking process or a process using slurry as
an intermediate. Each of these processes has its own merits and
demerits; however, whichever process is employed, the sheet tobacco
obtained has low expansion coefficient.
[0004] Examined Japanese Patent Publication (KOKOKU) No. 56-19225
discloses a process for manufacturing sheet tobacco with high
expansion coefficient. This conventional process utilizes
techniques for producing nonwoven fabric. Specifically, first, a
sheet-like mat is formed using a fibrous tobacco material, and the
formed mat is then impregnated with a liquid binder to obtain sheet
tobacco.
[0005] To make use of the above techniques for producing nonwoven
fabric, the tobacco material to be used must be of fibers longer
than a certain length. Thus, only fibers obtained from stalks and
stems of tobacco plant can be used as the tobacco material, and
small pieces of shredded tobacco, fragments thereof, etc. produced
in the process of manufacture of cigarettes or filter cigarettes
practically cannot be reused as the tobacco material.
DISCLOSURE OF THE INVENTION
[0006] An object of the present invention is to provide sheet
tobacco which can enhance the reusability of tobacco material and
has high expansion coefficient, and a process and system for
manufacturing such sheet tobacco.
[0007] Sheet tobacco according to the present invention has a
two-layer structure including a tobacco powder layer and a carrier
layer covering one side of the tobacco powder layer and made of
nonwoven plant fibers, the tobacco powder layer containing a
tobacco powder material and a binder.
[0008] The sheet tobacco of the present invention may further
include a cover layer. The cover layer is made of nonwoven plant
fibers and covers the other side of the tobacco powder layer. In
this case, the sheet tobacco has a three-layer structure wherein
the tobacco powder layer is sandwiched between the carrier layer
and the cover layer.
[0009] The carrier layer and the cover layer serve to increase not
only the expansion coefficient of the sheet tobacco but the
mechanical strength of same. As the powder material of the tobacco
powder layer, fine powder which is obtained from small pieces of
shredded tobacco and fragments thereof produced in the process of
manufacture of cigarettes or filter cigarettes can be used. The
sheet tobacco of the present invention can therefore greatly
enhance the reusability of the tobacco material.
[0010] Preferably, the tobacco powder layer has a basis weight of
30 to 200 g/m.sup.2, and the carrier layer and the cover layer each
have a basis weight of 3 to 50 g/m.sup.2. Also, the content ratio
of the binder, for example, cornstarch, to the tobacco powder
material in the tobacco powder layer is preferably not greater than
15% by weight. The layers having such basis weights and the binder
content impart sufficient original smoking taste and flavor to the
sheet tobacco.
[0011] The binder is preferably used not only to bind the powder
material of the tobacco powder layer, but also to bind together the
plant fibers used in the carrier layer and/or the cover layer. In
this case, no other binder needs to be used for the plant fibers,
making it possible to reduce the binder content in the sheet
tobacco.
[0012] The sheet tobacco according to the present invention may
further include a layer of tobacco particles. The tobacco particle
layer contains particles of tobacco stems and laminas and is
sandwiched between the carrier layer and the tobacco powder layer
or between the tobacco powder layer and the cover layer.
[0013] A sheet tobacco manufacturing process according to the
present invention comprises: a preparing step of preparing a
carrier sheet of nonwoven plant fibers; a forming step of spreading
a tobacco powder material on the carrier sheet to form a tobacco
powder layer covering one side of the carrier sheet; an adding step
of adding a binder to the tobacco powder layer during or after the
forming step; and a binding step of binding the powder material in
the tobacco powder layer as well as the tobacco powder layer and
the carrier sheet to each other by means of the binder.
[0014] With the above manufacturing process, sheet tobacco with a
two-layer structure is obtained which includes the tobacco powder
layer and the carrier sheet as the carrier layer.
[0015] Preferably, the carrier sheet is formed by a dry nonwoven
fabric production process, and the tobacco powder layer is formed
on the carrier sheet continuously following the formation of the
carrier sheet. This procedure permits the binder in the tobacco
powder layer to be used also to bind together the plant fibers in
the carrier sheet.
[0016] Since the carrier sheet is formed by a dry process as
mentioned above, the quantity of water used in the formation of the
carrier sheet is small. Accordingly, the cost of drying the carrier
sheet can be reduced, and also the carrier sheet can be prevented
from being deteriorated in smoking taste and flavor due to the
drying.
[0017] After the tobacco powder layer is formed, a cover sheet made
of nonwoven plant fibers, like the carrier sheet, may be formed on
the tobacco powder layer. In this case, the sheet tobacco has a
three-layer structure wherein the tobacco powder layer is
sandwiched between the carrier sheet and the cover sheet.
[0018] Preferably, the cover sheet on the tobacco powder layer also
is formed by a dry nonwoven fabric production process continuously
following the formation of the tobacco powder layer.
[0019] In the aforementioned binding step, the binder added to the
tobacco powder layer serves to bind together the plant fibers in
the carrier sheet and the cover sheet. Thus, no other binder is
required for the carrier sheet or the cover sheet.
[0020] Specifically, the aforementioned adding step is performed by
adding a binder of powder or liquid form to the tobacco powder
layer in the process of formation of the tobacco powder layer.
Preferably, the binder contains cornstarch as a main component.
Where the binder used is in powder form, the tobacco powder layer
and the carrier sheet, as well as the cover sheet, are made to be
impregnated with a solvent for the binder, for example, water,
prior to the binding step.
[0021] The binding step is carried out by pressing the two-layer
sheet tobacco constituted by the tobacco powder layer and the
carrier sheet or the three-layer sheet tobacco constituted by the
tobacco powder layer, the carrier sheet and the cover sheet with
heat applied thereto. In the process of the binding step, the
binder binds together the powder material in the tobacco powder
layer, binds the tobacco powder layer and the carrier sheet to each
other, and also binds the tobacco powder layer and the cover sheet
to each other. More specifically, in the case where the binder is
in powder form, the binder dissolves in the solvent, forming a
binder liquid. The binder liquid infiltrates also into the carrier
sheet and the cover sheet, and when heated, the solvent of the
binder liquid evaporates, so that the plant fibers are bound
together by the binder.
[0022] The manufacturing process of the present invention may
further comprise the step of forming a tobacco particle layer
between the carrier sheet and the tobacco powder layer or between
the tobacco powder layer and the cover sheet. The tobacco particle
layer is made of particles of tobacco stems and laminas.
[0023] A sheet tobacco manufacturing system according to the
present invention comprises: an endless net conveyor traveling in
one direction; an upstream-side forming device for forming a
carrier sheet of nonwoven plant fibers on the net conveyor; a
powder spreading device for spreading a tobacco powder material on
the carrier sheet to form a tobacco powder layer covering the
carrier sheet; and a pressing device for heating and pressing the
carrier sheet and the tobacco powder layer.
[0024] Preferably, a spraying device is arranged on an upstream
side of the upstream-side forming device as viewed in the traveling
direction of the net conveyor. The spraying device wets in advance
the net conveyor with a predetermined liquid, to facilitate the
peeling of the sheet tobacco from the net conveyor.
[0025] The manufacturing system may further comprise a
downstream-side forming device for forming the cover sheet. The
downstream-side forming device includes a fiber spreading unit
arranged above the net conveyor for spreading plant fibers toward
the net conveyor, a mesh conveyor arranged between the fiber
spreading unit and the net conveyor, the mesh conveyor sucking
thereon the plant fibers spread from the fiber spreading unit to
form a cover sheet and transporting the cover sheet toward the net
conveyor, and peeling means for peeling the cover sheet from the
mesh conveyor to allow the cover sheet on the mesh conveyor to be
transferred onto the tobacco powder layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a schematic view showing a manufacturing system
according to a first embodiment;
[0027] FIG. 2 is a view showing a state of a mat with a two-layer
structure just after being formed in the system of FIG. 1;
[0028] FIG. 3 is a view illustrating spraying of the mat of FIG. 2
with water;
[0029] FIG. 4 is a view illustrating heating of the mat of FIG.
2;
[0030] FIG. 5 is a view illustrating pressing of the mat of FIG.
2;
[0031] FIG. 6 is a partly broken perspective view of produced sheet
tobacco having a two-layer structure;
[0032] FIG. 7 is a schematic view showing part of a manufacturing
system according to a second embodiment;
[0033] FIG. 8 is a view showing a state of a mat with a three-layer
structure just after being formed in the system shown in FIG.
7;
[0034] FIG. 9 is a partly broken perspective view of produced sheet
tobacco having a three-layer structure;
[0035] FIG. 10 is a flowchart illustrating a process for
manufacturing sheet tobacco with a two- or three-layer
structure;
[0036] FIG. 11 is a schematic view showing a manufacturing system
according to a third embodiment;
[0037] FIG. 12 is an enlarged view showing part of an upstream-side
layer deposition device appearing in FIG. 11;
[0038] FIG. 13 is an enlarged plan view of a vibrating feeder
appearing in FIG. 11;
[0039] FIG. 14 is a side view of a powder spreading device
appearing in FIG. 11;
[0040] FIG. 15 is an enlarged view of a downstream-side layer
deposition device appearing in FIG. 11;
[0041] FIG. 16 is a partly broken perspective view of produced
sheet tobacco having a four-layer structure; and
[0042] FIG. 17 is an enlarged view of a pressing device appearing
in FIG. 11.
BEST MODE OF CARRYING OUT THE INVENTION
[0043] FIG. 1 schematically illustrates a manufacturing system
according to a first embodiment for carrying out a sheet tobacco
manufacturing process.
[0044] The manufacturing system includes an endless net conveyor 2.
The net conveyor 2 has a net surface 3 traveling from right to
left, as viewed in FIG. 1, and the net surface 3 passes a pulp
layer deposition device 4. The layer deposition device 4 spreads
plant fibers uniformly on the net surface 3 of the net conveyor 2,
whereby a web of plant fibers, that is, a carrier sheet A, is
formed on the net surface 3. More specifically, the layer
deposition device 4 includes a fiber spreading unit 6 arranged
above the net conveyor 2 and a suction box 8 arranged below the net
surface 3, and the net surface 3 passes between the fiber spreading
unit 6 and the suction box 8.
[0045] The fiber spreading unit 6 is connected through a pipe 10
and a fan 12 to an opening machine 14. The opening machine 14
coarsely crushes wood pulp P. The crushed fibers are transported
from the opening machine 14 toward the fiber spreading unit 6 by
means of the fan 12. The fiber spreading unit 6 has a chamber 7
opening to the net surface 3, and the fibers transported by the fan
12 are fed into the chamber 7. Rotatable agitating blades 9 are
arranged in the chamber 7, and a fine mesh screen 11 is attached to
the open end of the chamber 7.
[0046] The fibers supplied to the chamber 7 are agitated by the
rotation of the agitating blades 9 while at the same time are
discharged uniformly to the net surface 3 of the net conveyor 2
through the fine mesh screen 11 under the influence of suction by
the suction box 8. Consequently, the discharged fibers are
uniformly deposited on the net surface 3, thus forming the carrier
sheet A. The carrier sheet A formed in this manner travels with the
net surface 3. The fibers have an average length of about 2 mm, and
the carrier sheet A has a basis weight of 3 to 50 g/m.sup.2, for
example, 12 g/m.sup.2.
[0047] The chamber 7 is connected to the opening machine 14 also
through a return pipe 16, and the suction box 8 is connected to a
bag filter 20 through a suction fan 18.
[0048] A powder spreading device 22 is arranged above the net
surface 3 on a downstream side of the pulp layer deposition device
4. There are various types of powder spreading device, and in this
embodiment, the powder spreading device 22 includes a hopper 24, a
roll 26 having a wire wound around an outer peripheral surface
thereof, a vibrating brush 28, and a vibrating sieve 30. The hopper
24 stores a powder mixture therein. Specifically, the powder
mixture includes mainly powder of tobacco laminas admixed with
powder of cornstarch as a binder. As the roll 26 is rotated, the
powder mixture in the hopper 24 transfers to the roll 26 and drops
down toward the vibrating sieve 30. The powder mixture then passes
through the vibrating sieve 30 and is spread uniformly over the
carrier sheet A on the net surface 3. Immediately after passing
under the powder spreading device 22, therefore, the carrier sheet
A has a tobacco powder layer B of the powder mixture formed
thereon, as shown in FIG. 2. As a consequence, a two-layer mat M
having the carrier sheet A and the tobacco powder layer B is formed
on the net conveyor 2.
[0049] The tobacco powder layer B has a basis weight of 30 to 200
g/m.sup.2, for example, 88 g/m.sup.2. Also, the proportion of the
binder powder to the lamina powder in the powder mixture stored in
the hopper 24 is not greater than 17% by weight. More specifically,
the powder mixture consists of 91 wt % lamina powder and 9 wt %
binder powder, and the average particle size of the lamina powder
and the binder powder is preferably 10 .mu.m to 500 .mu.m.
[0050] An array of spray nozzles 34 is arranged above the net
conveyor 2 on a downstream side of the powder spreading device 22.
As shown in FIG. 3, the spray nozzles 34 spray a solvent for the
binder powder, for example, water W, uniformly onto the mat M. The
quantity of water sprayed in this case is 20 to 70 wt %, preferably
40 wt %, with respect to the mat M. Specifically, water is sprayed
on the mat M at a rate of 40 g/m.sup.2.
[0051] Accordingly, after passing under the spray nozzle array 34,
the mat M, that is, the tobacco powder layer B and the carrier
sheet A are uniformly impregnated with water.
[0052] Subsequently, the mat M is introduced from the net conveyor
2 into a pressing device 36. The pressing device 36 has a pair of
heat-resistant belt conveyors 38, and a transport path for the mat
M is defined between the belt conveyors 38. The mat M delivered
from the net conveyer 2 enters the transport path from an inlet
thereof and is transported by the upper and lower belt conveyors 38
while being held therebetween. Heaters 40 are arranged inside the
respective belt conveyors 38 and heat the mat M from above and
below, as shown in FIG. 4, up to a temperature of 50 to 150.degree.
C., for example, 120.degree. C. As a result, the water in the mat M
evaporates. Further, upper and lower press rollers 42 are rotatably
arranged at a location just short of an outlet of the transport
path, and press the mat M through the belt conveyors 38, as shown
in FIG. 5. A pressure applied to the mat M is 1 to 10 kg/cm.sup.2,
for example, 5 kg/cm.sup.2.
[0053] As the mat M is subjected to the heating and pressing as
mentioned above, the binder powder becomes pasty and the pasty
binder uniformly infiltrates not only into the tobacco powder layer
B but also into the carrier sheet A. Consequently, the binder binds
together the lamina particles in the tobacco powder layer B, and
also binds together the tobacco powder layer B and the carrier
sheet A as well as the plant fibers in the carrier sheet A.
[0054] Subsequently, the mat M is guided from the pressing device
36 into a far infrared dryer 44 of air circulation type, for
example. The dryer 44 also has a belt conveyor 46 for receiving the
mat M transferred thereto. As the mat M is transported by the belt
conveyor 46, the water content of the mat M is reduced to 5 to 20
wt %, for example, 11 wt %.
[0055] Thus, the mat M is passed through the dryer 44, whereupon
sheet tobacco as shown in FIG. 6 is obtained. The sheet tobacco has
a two-layer structure wherein the tobacco powder layer B is formed
on the nonwoven carrier sheet A.
[0056] The two-layer sheet tobacco shown in FIG. 6 has the
below-mentioned values as its physical properties.
1 Weight: 100 g/m.sup.3 Tensile strength: 4.9 N/15 mm width
Expansion coefficient: 3.51 cc/g Apparent density: 0.732 g/cm.sup.3
Water resistance time: 48 min. Nicotine content: 1.19 D.M. %
[0057] FIG. 7 shows part of a manufacturing system according to a
second embodiment for carrying out a sheet tobacco manufacturing
process.
[0058] The manufacturing system of the second embodiment has two
pulp layer deposition devices 4 between which the powder spreading
device 22 is located. With this manufacturing system, a cover sheet
C can be additionally formed on the mat M, that is, on the tobacco
powder layer B. The cover sheet C is a pulp-deposited sheet similar
to the carrier sheet A. Accordingly, after passing under the
downstream-side layer deposition device 4, the mat M has a
three-layer structure wherein the tobacco powder layer B is
sandwiched between the carrier sheet A and the cover sheet C, as
shown in FIGS. 8 and 9.
[0059] In the case of the mat M with a three-layer structure, the
basis weight of each of the carrier sheet A and the cover sheet C
is 3 to 50 g/m.sup.2, for example, 9 g/m.sup.2, and the basis
weight of the tobacco powder layer B is 30 to 200 g/m.sup.2, for
example, 132 g/m.sup.2. The weight ratio of the binder powder to
the lamina powder in the powder mixture is 10 to 90. Also, the
array of the spray nozzles 34 sprays water W in an amount of 20 to
70 wt %, for example, 40 wt % with respect to the weight of the mat
M. In this case, the quantity of water sprayed on the mat M is 52
g/m.sup.2.
[0060] Further, the mat M is heated in the pressing device 36 at a
temperature of 50 to 150.degree. C., for example, 120.degree. C.,
and is pressed under a pressure of 1 to 10 kg/cm.sup.2, for
example, 5 kg/cm.sup.2.
[0061] The sheet tobacco with a three-layer structure has the
following values as its physical properties:
2 Weight: 100 g/m.sup.3 Tensile strength: 5.4 N/15 mm width
Expansion coefficient: 4.1 cc/g Apparent density: 0.744 g/cm.sup.3
Water resistance time: 59.6 min. Nicotine content: 1.23 D.M. %
[0062] Referring now to FIG. 10, there are shown processes for
manufacturing sheet tobacco by using the manufacturing systems
shown in FIGS. 1 and 7. The lower part of the flowchart branches
into two, the left branch indicating the manufacture of the
two-layer sheet tobacco, and the right branch indicating the
manufacture of the three-layer sheet tobacco.
[0063] As seen from FIG. 10, the tobacco powder layer B may be
formed by spreading the lamina powder and the binder powder
separately over the carrier sheet A, or by alternately spreading
the lamina powder and the binder powder.
[0064] In the case where the powder spreading device 22 spreads the
lamina powder alone on the carrier sheet A, a binder liquid in
which cornstarch is dissolved as the binder may be sprayed from the
spray nozzle array 34.
[0065] Also, the carrier sheet A and the cover sheet C may each be
formed in advance by depositing pulp and stored in the form of a
roll. In this case, the tobacco powder layer B is formed on the
carrier sheet A delivered from the roll. Where the three-layer mat
M is to be produced, the cover sheet C delivered from the roll is
lapped over the tobacco powder layer B. Also, in cases where the
carrier sheet A and the cover sheet C are formed beforehand, the
sheets A and C may each be formed by a wet nonwoven fabric
production process.
[0066] As the binder, not only cornstarch but various other binders
used in the tobacco manufacturing industry may be used. Further,
the tobacco powder layer may be admixed with other substances than
the binder, such as combustion adjuster, inorganic filler,
humectant, water resistance modifier and flavoring material, so
that the quality, flavor and taste of the sheet tobacco can be
adjusted.
[0067] The plant fibers for forming the carrier sheet and the cover
sheet may be admixed with fibers obtained from tobacco stalks and
stems.
[0068] FIG. 11 shows a manufacturing system according to a third
embodiment for carrying out a sheet tobacco manufacturing
process.
[0069] In the manufacturing system of FIG. 11, the net surface 3 of
the net conveyor 2 extends through the pressing device 36. Inside
the net conveyor 2 is arranged a suction box 50 at a location under
the upstream-side layer deposition device 4. Also, to permit
satisfactory deposition of pulp, an array of spray nozzles 52 is
arranged above the net conveyor 2 on an upstream side of the layer
deposition device 4, that is, the fiber spreading unit 6 thereof.
The spray nozzles 52 spray water on the net surface 3.
[0070] As shown in FIG. 12, the chamber 7 of the upstream-side
fiber spreading unit 6 is directly connected to an opening device
54 of drum type, which in turn is connected to a hammer mill
through a pneumatic feed pipe (not shown). Pulp Q coarsely crushed
by the hammer mill is transported through the pneumatic feed pipe
to the opening device 54. The opening device 54 reduces the pulp Q
to separate fibers and supplies the fibers to the chamber 7 of the
fiber spreading unit 6. Since the opening device 54 is arranged
close to the fiber spreading unit 6, a fixed quantity of fibers can
be constantly supplied from the opening device 54 to the chamber 7.
This enables the fiber spreading unit 6 to form the carrier sheet A
with higher accuracy on the net surface 3 of the net conveyor
2.
[0071] A feeder unit 56 is arranged above the net conveyor 2 at a
location between the upstream-side fiber spreading unit 6 and the
powder spreading unit 22. The feeder unit 56 spreads particles of
stems and laminas of tobacco, etc. over the carrier sheet A, to
form a tobacco particle layer B' on the carrier sheet A.
[0072] As shown in FIG. 13, the feeder unit 56 includes a main
vibrating feeder 58 and a sub vibrating feeder 60. Each vibrating
feeder is provided with a hopper 62 storing a mixture of particles
of tobacco stems and laminas, etc. A flat pipe-shaped delivery
guide 64 extends from each hopper 62 and has an oblique open edge
66 at a distal end thereof. The delivery guides 64 vibrate in
respective directions indicated by the arrows in the figure, to
deliver the mixtures in the corresponding hoppers 62 in their
vibrating directions. The mixtures delivered in this manner are
spread uniformly on the carrier sheet A from the entire lengths of
the open edges 66 of the delivery guides 64. As is clear from FIG.
13, the vibrating feeders 58 and 60 together have a mixture
spreading region covering the entire width of the carrier sheet A,
whereby the particle layer B' of the mixture can be uniformly
formed over the carrier sheet A.
[0073] In cases where the open edge 66 of the main feeder 58 has a
length covering the entire width of the carrier sheet A, the feeder
unit 56 may include only the main vibrating feeder 58. Also, the
feeder unit 56 may be arranged between the powder spreading device
22 and the spray nozzle array 34.
[0074] In the third embodiment, the powder spreading device 22 has
a vibrator 70, as shown in FIG. 14, and the vibrator 70 vibrates
the hopper 24 to allow the powder mixture to be retained on the
roll 26 without fail.
[0075] The powder spreading device 22 forms a tobacco powder layer
B on the particle layer B'. Subsequently, the spray nozzle array 34
sprays water W uniformly over the tobacco powder layer B, so that
the water W infiltrates into the particle layer B' and the carrier
sheet A through the tobacco powder layer B.
[0076] As shown in FIG. 15, the downstream-side layer deposition
device 4 includes a fiber spreading unit similar to the unit 6
shown in FIG. 12, and a transfer unit 72. The transfer unit 72 is
arranged between the net conveyor 2 and the fiber spreading unit 6
and has an endless mesh conveyor 74 similar to the net conveyor 2.
The mesh conveyor 74 has a mesh surface 76 facing the fine mesh
screen 11 of the fiber spreading unit 6, and a mesh surface 78
facing the net conveyor 2, that is, the net surface 3. The mesh
conveyor 74 travels in a direction opposite to that of the net
conveyor 2 at the same speed as the net conveyor 2. Accordingly,
the mesh surface 78 of the mesh conveyor 74 moves in the same
direction and at the same speed as the net surface 3.
[0077] A suction box 80 is arranged inside the mesh conveyor 74
along the mesh surface 76 and produces a predetermined suction
force acting upon the mesh surface 76. Accordingly, the plant
fibers spread from the fiber spreading unit 6 form a cover sheet C
on the mesh surface 76, and the cover sheet C is transported
together with the mesh conveyor 74.
[0078] Inside the mesh conveyor 74 is also arranged a rotating rod
82 in the vicinity of the mesh surface 78. More specifically, the
rotating rod 82 is a square rod located at an upstream portion of
the mesh surface 78. When rotated, the rotating rod 82 periodically
taps on the mesh surface 78 to vibrate the same, whereby the cover
sheet C transported from the mesh surface 76 is shaken off toward
the net surface 3 and is lapped over the tobacco powder layer
B.
[0079] Thus, after the net surface 3 passes under the
downstream-side layer deposition device 4, a four-layer mat M
having the particle layer B', the tobacco powder layer B and the
cover sheet C successively formed on the carrier sheet A, as shown
in FIG. 16, is formed on the net surface 3.
[0080] An array of spray nozzles 81 is arranged on an upstream side
of the transfer unit 72 and sprays water so that the water may be
infiltrated into the carrier sheet A through the tobacco powder
layer B and the particle layer B'.
[0081] The mat M then passes through the aforementioned pressing
device 36 to be subjected to heating and pressing. As shown in FIG.
17, the pressing device 36 of the third embodiment has upper and
lower heat-resistant belt conveyors 38, which hold the mat M and
the net surface 3 therebetween and cause the mat M to travel in
cooperation with the net surface 3. The pressing device 36 has a
plurality of heaters 40 arranged inside the individual belt
conveyors 38 along the net surface 3.
[0082] After passing through the pressing device 36, the mat M
transfers from the net conveyor 2 to another conveyor 86, as shown
in FIG. 11, and is transported by the conveyor 86. An array of
spray nozzles 88 is arranged above the conveyor 86 for spraying
water W on the mat M, so that the water content of the mat M can be
adjusted as required.
[0083] The conveyor 86 may be passed through either an embossing
device 90 or a rippling device 92 on a downstream side of a dryer
(not shown), to subject the mat M to embossing or rippling.
[0084] Compared with the manufacturing processes and systems
according to the first and second embodiments, the manufacturing
process and system of the third embodiment additionally provide the
following advantages:
[0085] a) Prior to the formation of the carrier sheet A on the net
conveyor 2, that is, on the net surface 3, the net surface 3 is
sprayed with water W from the spray nozzle array 52 and thus is in
a wet state. Accordingly, when pulp is deposited in layer form, it
does not slip on the net conveyor 2 and forms a layer
satisfactorily.
[0086] b) The mat M includes, besides the tobacco powder layer B,
the particle layer B' containing particles of tobacco stems and
laminas, etc. This makes it possible to manufacture sheet tobacco
having an even higher expansion coefficient.
[0087] c) The cover sheet C is first formed on the mesh conveyor 74
of the transfer unit 72 and then is transferred to be lapped over
the tobacco powder layer B. This method of transferring the cover
sheet C can prevent the disadvantage of directly depositing pulp to
form the cover sheet C on the carrier sheet A with the tobacco
powder layer B and the particle layer B' therebetween, namely, the
disadvantage that the powder materials of the tobacco powder layer
and the particle layer are sucked into the carrier sheet A when the
pulp layer is formed. Also, since the transfer unit 72 is provided
with the rotating rod 82, the cover sheet C can be peeled from the
mesh conveyor 74 without fail to be transferred onto the tobacco
powder layer B.
[0088] It is to be understood that the present invention is not
limited to the embodiments described above, and that various
changes and modifications may be effected therein by one skilled in
the art without departing from the scope or spirit of the
invention.
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