Note: Descriptions are shown in the official language in which they were submitted.
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FO~TION OF TOBACCO BLENDS
The present invention is concerned with formation
of tobacco blends for cigarette formation.
This application is a division of copending
application Serial No. 372,861 filed March 12, 1981.
In the manufacture of cigarettes, tobacco leaf is
processed to separate the stems from the lamina. The
lamina are shredded and formed into cigarettes or other
smoking articles. The stems are not successfully
utilizable as such in cigarette making because of their
relatively large diameter, their hard nature and poor
burning properties.
Nevertheless, tobacco stem material constitutes a
substantial proportion of the leaf, usually about 20 to
25% of the weight thereof, and contains tar, nicotine
and other materials common to the lamina. In the past,
therefore, efforts have been made to process the stem
material for use i`n smoking articles but such
procedures have generally been unsatisfactory,
unsuccessful or inefficient.
It now has been found that tobacco stem material
can be satisfactorily, successfully and efficiently
blended with tobacco lamina for use in forming
cigarettes by a combination of steps.
In accordance with the present invention, there is
provided a method of forming a tobacco feed material
suitable for the formation of cigarettes therefrom,
which comprises: moistening tobacco stem material in
water to a moisture content of about 30 to about 60% by
weight, mechanically fiberizing the moistened tobacco
stem material to a shredded fibrous form, partially
drying the shredded stem material to form
partially-dried shredded stem material of a lower
moisture content in the range of about 19 to about 35
35 wt.%, blending the partially-dried shredded stem
material with shredded tobacco lamina material having a
substantially similar moisture content in the
proportion of about 2 to about 50% by weight of the
partially-dried shredded stem material and about 98 to
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about 50% by weight of the shredded tobacco lamina, and
drying the blend so formed to a moisture content of
about 10 to about 16 wt.%.
In the method, a mass of tobacco stem material
which may first be cut into convenient lengths, for
example, about 0.5 to 6 inches, is initially treated
with water to moisten the same to an overall moisture
content of about 30 to about 60% by weight. preferably
about 50 to about 60% by weight.
The procedure may involve soaking of the mass of
stem material in water at atmospheric pressure in such
a way as to avoid any substantial loss of water
extractibles from the mass. This result may be
achieved by initially exposing the tobacco mass to
water for about 5 to about 15 minutes, so as to permit
the mass to soak up the water. The water has a volume
sufficient to permit the desired moisture content to be
achieved and may have~any convenient temperature up to
the boiling point thereof, such as about 15 to about
90C, higher temperatures speeding up the absorbtion of
the water.
Thereafter, the exposed mass is stored in confined
manner to permit the soaked up water to permeate
through the mass and into the tobacco stem material
therein and to evenly distribute therethrough. The
confinement may be from about 0.25 to about 24 hours,
preferably about 1 to about 4 hours.
Alternatively, the tobacco mass may be exposed to
water in a suitable conditioning drum for a period
sufficient to achieve the desired overall moisture
content.
The mass of soaked stem material resulting from
the moistening step is mechanically fiberized to a
shredded fibrous form. Apparatus suitable for carrying
3~ out the mechanical fiberizing step is a revolving disc
refiner, such as are manufactured by Bauer Bros.,
Sprout-Waldron and American Defibrator. The disc
refiner includes two disc-like counter-rotating plates
which are closely spaced apart, and at least one has a
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face pattern designed to fiberize the material fed
- between the plates.
The disc refiner usually is of the
counter-rotating type with the plates spaced apart
about 0.05 to about 0.3 inches, preferably 0.13 to 0.18
inches, operating at atmospheric pressure. The optimum
plate-spacing and pattern, rotational speed and
retention time are readily determined for a particular
tobacco stem material and type of disc refiner used.
The product resulting from the refiner generally has
the appearance and size of shredded tobacco lamina,
namely, bundles of loosely integrated fibres.
Some temperature rise results in the mechanical
fiberizing step, as a result of the friction between
lS the plate ribs and the tobacco stem material. The
soaked mass of tobacco stem material may be fed to the
mechanical fiberizing step at any convenient
temperature up to the boiling point of the water.
The effect of such heat on the final product is to
increase the filling power and pressure drop parameters
and at the same time increase the burn rate. The
temperature of the mass, therefore, may be used to vary
the parameters possessed by the product.
The temperature usually ranges from about 15 to
about 90C. When lower temperature operations are
desired, the temperature of the mass entering the
mechanical fiberizing step may vary from about 10 to
about 35C, preferably about 15 to about 25C.
The shredded stem material which results from the
mechanical fiberizing step is dried first to an
intermediate moisture level of about 19 to about 35
wt.~, blended at that moisture level with the desired
quantity of shredded lamina material having a
substantially similar moisture content, and then drying
the blend to the final moisture content of about 10 to
about 16 wt.%, preferably about 12 to about 15 wt.%.
In one preferred embodiment of the invention, the
shredded stem material is discharged directly from the
disc refiner into a flowing air stream to maintain the
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fibres in a substantially separated condition. This
- action may be combined with cooling of the shredded
stem material by using an air stream having a
temperature below that of the exiting shredded stem
material, for example, about 20 to 25C.
The maintenance of the fibres in a separated
condition decreases the incidence of "balling", or the
joining together and curling up of the fibres to form
ball-like particles which are unusable in the final
product. Once the shredded fibres have been discharged
from the air stream, for example, using a flexible
shell air-lock, they are dried to the intermediate
moisture level of about 19 to about 35% by weight,
using any conventional tobacco drying equipment, such
i5 as, a rotary tumbler drier.
Thereafter, any ball-like particles may be removed
from the fibres by any conventional winnowing
technique, such as, by air separation and recycled to
the refiner, prior to blending the shredded stem
material with shredded tobacco lamina, and drying the
blend to the final moisture level.
The use of the moistening and fiberizing procedure
to produce a shredded stem material having a physical
appearance and size similar to shredded lamina and the
use of the two-stage drying operation with intermediate
blending of the shredded lamina material, permits the
tobacco stem material to be successfully used as a
cigarette filler material.
In summary of this disclosure, the present
invention provides a novel method of achieving blends
of tobacco stem material and tobacco lamina material
useful in cigarette making. Modifications are possible
within the scope of this invention.
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