Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to the production of filter
means, and relates more particularly to tobacco smoke filter
elements. More specifically, the instant inventive concepts
are primarily concerned with producing filter means for cigar-
ettes, although the products of this invention are generally
useful as filters, particularly for tobacco smoking means,
whether they be cigarettes, cigars, pipes or the like. Since
filters for cigarettes are particularly commercially important,
the basic embodiments of the instant invention will be discussed
as they relate to the production of filtered cigarettes. :
Various prior art techniques are known for making
filters for use in connection with cigarettes and the like,
although the resultant products, in general, have one or more
disadvantages. Perhaps the most important property of the fil-
ter means is its efficiency, that is, its ability to remove
undesirable constituents from the tobacco smoke. Filtration
efficiency is ordinarily measured in terms of the percentage
of total particulate material (TPM) removed from the smoke,
although there is also some concern for the percentage of gas
phase constituents which the filter means is capable of removing.
While filtration efficiency is perhaps the most important property
of cigarette filter means, other properties must also be con-
sidered, including pressure drop, taste, hardness, appearance
and cost. It is necessary to produce a filter which satisfies
commercial requirements in each of these areas. Frequently, a
compromise of certain properties is required in order to satisfy
the need for others. For example, the most commonly utilized
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cellulose acetate filter means has a relatively low filtration
- efficiency since increased efficiency can only be obtained by
increasing the density of the filter material or the length of
the filter element, both of which produce a pressure drop across
the filter which is excessive and unacceptable from a commercial
standpoint. While various suggestions have been made for the
production of filter means which have improved filtering proper- -
ties, most prior art developments have not been commercially -
acceptable either because the resulting means have been found
to have objectionable "taste" characteristics whereby cigarettes
provided with such filtering means fail to satisfy a large seg-
ment of the smoking public, or because the techniques and/or the
materials utilized in the production of such filter means have ~-
increased the cost excessively.
High filtration efficiency is considered by the indus-
try to be removal of 60 percent or more of total particulate -
matter. Cigarette filters having such properties are presently
being produced in accordance with the teachings of U.S. Patents
Nos. 3,533,416, 3,599,646, 3,637,447, 3,648,711, 3,805,801 and - -
3,810,477.
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A further development in the production of tobacco
smoke filter means is disclosed in U.S. Patent No. 3,811,451.
It is always desirable, however, to provide further
techniques for the production of cigarette filter elements or
the like which provide high filtration with correspondingly low
pressure drop, and which may be made at high speeds by eliminat-
ing certain operations of prior art techniques, thereby minimiz-
ing manufacturing costs. It is this area with which the instant
invention is concerned.
Thus, it is a primary object of this invention to
provide a cigarette filter means or the like and a method and
means for manufacturing same wherein the products have a high
filtration efficiency, satisfactory pressure drop and other com-
mercial requirements, and wherein the method and means utilized
enable high speed production of the final product.
A further object of this invention is to provide a
cigarette filter having a multiplicity of embodiments which
enable selective production of a product having a chosen path
for passage of smoke, in some embodiments non-smoke permeable
elements being incorporated to direct the smoke, while in other
embodiments, the entire filter means being producted from mat-
erials that offer filtration properties.
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Another object of this invention is the provision of
a method and means for forming an annul ar intermediate element
of a smoke filtering material and for depositing axially spaced
inner plug members within the internal bore of the intermediate
member.
Still a further object of this invention is to provide
techniques whereby the intermediate and inner members may be ~ -
crimped to assist in precluidng axial disengagement between
these elements.
Accordingly, the present invention provides an apparatus
for making smoke filters comprising: means for providing a
multiplicity of discrete inner plug members; means for axially 1~
spacing said inner members from each other and continuously .
feeding said axially spaced inner members along a path of -
travel; a source of a filtering material including a multiplicity
of fibrous elements; means defining a bonding zone in the form 1.
of an annular space in said path of travel of said inner members;
means for continuously passing said filtering material into ,-
and through said annular space in said bonding zone; means for
contacting said filtering material with a bond activating agent
in said bonding zone to bond said fibrous members of said
filtering material to each other at spaced contact points
thereby forming an elongated, smoke-permeable, annular intermed-
iate member having a continuous axial bore therein and defining
an annular tortuous path for passage of smoke; means for
continuously feeding said axially spaced inner members into : -
said bore to form discrete cavities within said intermediate
member separated from each other by said inner members; means
for overwrapping said intermediate member with an overwrapping ~-
material so as to juxtapose the inner surface of said over-
wrapping material with the exterior surface of said intermediate
member to form sealed areas precluding passage of smoke
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thereacross; and means for transversely severing the resulting
product at selected locations to form individual filter
elements.
The invention will now be described in more detail,
by way of example only, with reference to the accompanying
drawings, wherein: 5
Figure 1 is an enlarged perspective view of one
form of filtered cigarette produced according to this invention, .
parts being broken away for illustrative clarity and convenience;
10Figure 2 is a schematic view of a method and means L
for making filter elements according to the instant inventive
concepts;
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Figure 3 is a fragmentary view of a filter rod
produced according to this invention, parts being in section
and parts being broken away for illustrative
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clarity;
Figure 4 is a longitudinal sectional view through the
filter means of the cigarette of Figure 1, wherein the inner mem-
ber is formed of a smoke-permeable material, the paths of smoke
through the filter means being shown;
Figure 5 is a transverse sectional view taken substan-
tially along lines 5-5 of Figure 4;
Figure 6 is a view similar to Figure 4 through a modi-
fied embodiment of a filter means according to the instant inven-
tive concepts wherein the inner member is non-permeable to smoke,
the paths of travel of smoke through a filter means of this type
also being shown;
Figure 7 is a longitudinal sectional view through still
a further modified embodiment of the filter means according to
the instant inventive concepts wherein the intermediate and inner
members have been crimped to assist in precluding relative axial
movement between these members, the paths of travel of smoke -.
through this filter means also being shown;
Figure 8 is a transverse cross-sectional view taken.
substantially along lines 8-8 of Figure 7; -
Figure 9 is a fragmentary view, partially in cross-
section for illustrative clarity, showing a means for transversely
severing the inner rod to form discrete inner members, and then
axially spacing the inner members from each other; and
Figure 10 is a fragmentary cross-sectional view through
the portion of the manufacturing apparatus wherein the intermedi-
ate member is formed and the inner members are deposited within
the axial bore of the intermediate member in axially spaced
fashion.
Like reference characters refer to like parts through-
out the several views of the drawings.
Referring now to the drawings, and more particularly to
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Figure 1, a filtered cigarette according to the instant inventive
concepts is designated generally by the reference numeral 20 and
comprises basically a tobacco rod shown partially at 22 and a
filter element according to one embodiment of this invention
designated generally by the reference numeral 24, a conventional
tipping overwrap being shown in dotted lines at 26 securing the
tobacco rod and the filter element in end-to-end relationship
according to well known prior art techniques.
Filter element 24 comprises basically an axially elon-
gated, hollow, outer member 28 formed by conventional plug wrapas will be explained hereinafter in more detail, an axially
elongated, hollow, intermediate member 30 formed of a filtering
material, and an inner plug member 32 disposed within the inter-
mediate member 30.
It will be seen that the outer member 28 and the inter-
mediate member 30 are coextensive in axial length whereas the
inner member 32 is shorter than either of the foregoing elements
to define cavity means 34 within the intermediate member. In the
embodiment of Figure 1, it will be seen that the inner member 32
is spaced from both ends of the intermediate member 30 so that
discrete cavities 34 are formed at each end of the filter element
24.
At least the intermediate member 30 is preferably and
primarily formed from a continuous tow of cellulose acetate fila-
mentary material, although other filtering material may be used
with slight modifications. For example, filamentary tow formed
of other materials such as polyethylene, polypropylene and the
like, or even non-woven staple fibers of the type described in
some detail in U.S. Patents Nos. 3,297,041 and 3,552,400, may be
used in the production of the intermediate member 30. In fact,
it is even possible to produce this member from an extruded, open
celled foamed material, such as cellulose acetate foam or the
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like. However, since cellulose acetate filamentary tow is the
presently preferred material from a commercial standpoint, the
remainder of this specification will be directed to the use of
such material for the production of the intermediate member 30.
Thus, the intermediate member 30 is preferably formed of crimped
filamentary cellulose acetate members bonded together at their
contact points to form smoke-permeable elements defining tortuous
paths for passage of smoke therethrough. Filtering material of
this nature is well known, as are techniques for producing same.
According to one embodiment of this invention, the inner
member 32 is also formed of crimped filamentary cellulose acetate
members bonded together at their contact point to form a smoke-
permeable element defining tortuous paths for passage of smoke
therethrough. An element of this nature is shown in Figures 4
and 5. In Figure 4 the paths for passage of smoke through the
filter element 24 are shown by dashed arrows. Thus, it will be
seen that the smoke passes through both cavities 34, as well as
through the material of the intermediate member 30, and the mat-
erial of the inner member 32.
In Figure 3 a continuous rod 40 made up of a multipli-
city of integrally connected elements of the type shown at 24 in
Figuresl, 4 and 5, will be seen. This rod is severed transversely
along the lines 42,44 to produce individual filter elements such
as shown at 24. Of course, the rod 40 could be severed at other
locations to produce filter elements of different lengths. For
example severing the rod 40 at 46 would produce filter elements
which include a cavity means 34 at only one end, and only half
of an inner plug member 32, one end portion of which is coincident
with the end of the intermediate member 30. Moreover, the rod 40
could be severed in a manner such as to produce filter elements
of multiple length. It is common practice, in fact, to initially
product double filters which are then secured to two tobacco sec-
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tions by a common tipping overwrap following which individual
filtered cigarettes are formed by severing the double filter
at its midpoint.
Reference is now made to Figure 6 wherein a filter
element similar to the embodiment of Figures 1, 4 and 5 is shown,
with the inner member of the embodiment of Figure 6 being formed
of a non-smoke permeable material. Since, except for the mat-
erial of the inner member, the embodiment of Figure 6 is sub-
stantially identical to that of Figures 1, 4 and 5, the same
reference numeral has been used to designate similar parts,
followed by the suffix "a". It will be seen from the arrows in
Figure 6, that smoke passing through the filter element 24a,
passes through the individual cavities 34a and the intermediate
member 30a, but cannot pass centrally or axially of the filter
element, being forced radially outwardly through the annular wall
of the intermediate member 30a. In an embodiment of this type,
the inner member 32a may be formed of a variety of non-smoke
permeable materials. For example, an elongated rod of closed-
celled polystyrene may be extruded and transversely severed at
- 20 axially spaced locations to form discrete non-smoke permeable t
inner members. Of course, other non-smoke permeable materials
may be utilized for formation of the inner members 32a in an
obvious manner.
Referring now, particularly, to Figures 7 and 8,
another embodiment of the instant invention will be seen, wherein
parts similar to those of previous embodiments have been desig-
nated by the same reference numeral followed by suffix "b" to
facilitate an understanding of this embodiment. Effectively,
it will be seen that the filter element 24b shown in Figures 7
and 8 is half of a filter element such as shown at 24 in Figures
4 and 5 such as would result if the filter rod 40 were severed at
46, in addition to being severed at 42 and 44. Although the
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embodiment of Figures 7 and 8 has been shown as having a smoke-
permeable inner plug member 32b, it is obvious that a non-smoke
permeable inner member could be substituted therefor. However,
with this particular embodiment the use of a smoke-permeable plug
member 32b is desirable so as to set up smoke flow patterns of
the type shown by the arrows in Figure 7. This particular pattern
results from the provision of limited crimped portions forming
grooves or the like 38 which define cavity means between the outer --
surface of the intermediate member 3Ob and the inner surface of
the outer member 28b. The crimping which forms the grooves 38
functions, additionally, to embed portions of the material of the
; intermediate member 30b into portions of the inner member 32b as
will-be seen from Figures 7 and 8, assisting in precluding rela-
tive axial movement between these members. Of course, it is
important that the crimped portion of the outer surface of the ;-
intermediate member 30b be limited in nature so as to provide a
substantially uniform outer surface for the intermediate member
and, thus, a uniform support for the outer member throughout its
entire length.
In the absence of crimping such as shown at 38 in the
embodiment of Figures 7 and 8, the inner member is secured within
the intermediate member and, in turn, the intermediate member is
secured within the outer member, by having these elements in
press-fit relationship. Thus, the intermediate member is formed
` ~over the axially spaced inner members in a manner wherein the
intermediate member radially grips the inner member and, likewise,
~ the outer member is wrapped about the intermediate member under
j sufficient tension to preclude axial passage of smoke between
their mating surfaces and to preclude relative axial displacement
between these members.
Reference is now made particularly to Figure 2 and
Figures 9 and 10, for an overall method ana means utilized in pro-
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ducing filter elements in accordance with this invention.
Basically, the overall technique is similar in many respects to
the techniques shown and described in detail in U.S. Patent No.
3,637,447, referred to previously. According to an embodiment
of this invention wherein the inner member is formed from a
filtering material such as cellulose acetate tow, a source of
such filtering material is shown schematically at 50. The filter-
ing material 50 includes a multiplicity of bondable fibrous mem-
bers activated by contact with a hot fluid, such as steam. Thus,
the filtering material 50 is continuously pulled by garniture
means 52 into and through a conventional stuffer jet 54, steam
head 56 and cooling head 58 to produce a smoke-permeable rod 60
which is relatively self-supporting.
The rod 60 is transversely severed at axially spaced
locations to form discrete inner plug members 32 by a cutting
means 62, details of one form of which are shown particularly in
Figure 9. The cutting means 62 includes a plurality of radially,
circumferentially spaced blades 64 which are rotatably supported
as at 66 to transversely sever the rod 60.
The uncut portion of the rod 60, continuously moved by
the garniture means 52, pushes the discrete inner plug members 32
into an elongated tube 68 which is so dimensioned as to peripher-
ally seal the discrete inner plug members 32 as they slide through
its internal bore. As will be seen particularly in Figure 9, a
multiplicity of passageways 70 extending radially and angled for-
wardly in the direction of travel of the plug members 32, are
. provided in the tube 68 at a location wherein they communicate
with a manifold 72 connected through a conduit 74 to a source of
fluid pressure, such as pressurized air or the like, in a spacing
means 75. These jets of pressurized fluid, shown as dotted arrows
in Figure 9, are injected between adjacent plug members 32 so as
to axially separate them while they are pushed through the tube 68.
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Of course, other techniques and materials may be used
for the production of the inner rod and for transversely severing
such rod and axially spacing the resultant inner members, but
the device shown in Figure 9 has been found to function satis-
factorily.
With an arrangement of the foregoing type, the elongated
tube 68 may be simultaneously utilized to provide a mandrel
extending through a further stuffer jet 76 and into a further
steam head 78 to form an annular space for production of the
intermediate member 30 from a further filamentary tow material
such as shown at 80. Of course, with such an arrangement, the
tube 68 must extend into the steam head 78 past the points 82 at
which steam contacts the filamentary tow 80 to form the annular
intermediate member 30. As will be seen in Figure 10, the inner
members 32 are then deposited, in axially spaced relationship,
into the internal bore of the intermediate member 30 to form the
spaced cavity means 34.
Due to the resilient nature of the material utilized
in the formation of the inner and intermediate members, and the
use of a relatively thin walled tube 68, the inner and inter-
mediate members 32,30 will normally be in press-fit contact to
preclude relative axial movement between these members. However,
if desired, following passage of the composite formed of the
intermediate and inner members through a cooling head such as ~-
shown at 83, crimping wheels or the like, such as shown in
detail in Figures 10-13 of U.S. Patent No. 3,637,447, and desig-
nated schematically by the dashed lines at 84 in Figure 2, may
be utilized for forming limited external cavities such as shown
at 38 in Figures 7 and 8, and for embedding a portion of the
intermediate member in the outer surface of the inner member.
In either event, the composite rod is continuously
moved forwardly by a further garniture means 86 in which it is
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overwrapped by a conventional plug wrap, a source of which is
shown at 88, to form the outer member 28, and then severed
transversely at selected locations in a cutting means such as
shown schematically at 90.
Due to the substantially uniform and smooth outer
surface of the intermediate member 30, it will be seen that the
outer member 28 is uniformly supported throughout its entire
length. This avoids the need for an internal glue line to
secure the outer member in position as has been necessary with
certain prior art techniques.
Moreover, since the intermediate member is either
uncrimped or only slightly crimped to form relatively limited
external cavities such as shown at 38 in Figures 7 and 8, it
is not distorted as results from substantial crimping techniques
utilized according to the prior art. When the inner rod is sub-
stantially crimped, and thus distorted, it is necessary to use
a relatively heavy weight overwrap to form the outer member in
order to return the filtering material to a true cylindrical
shape. Since the techniques of this invention avoid the need
for any substantial crimping, a relatively light weight conven-
tional plug wrap may be used in producing the outer member,
minimizing production costs in an obvious manner.
The following data compares certain characteristics of
products made according to this invention with prior art products.
The type designated as "I" is a plug made according to this
invention wherein the inner member is formed of a cellulose
acetate tow. The type designated as "II" is a filter element
according to this invention wherein the inner member is formed
of a non-smoke permeable polystyrene plug. The type designated
as "III" is a single filter element of the type shown, for
example, in U.S. Patent No. 3,637,447 and the type designated as
"IV" is a double filter such as shown in U.S. Patent No. 3,805,801.
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Percent
Type Weight Pressure Drop Retention
- I 12.1 gms 2.4" 69
II 16.1 gms 1.0" 78
III 16.5 gms 2.8" 69
IV 13.4 gms 2.8" 65
It will be seen from the above that filter elements prepared
according to the instant inventive concepts compare favorably
with the prior art filters, while providing at least as good,
and frequently better, filtration efficiency. Other commercially
significant properties such as hardness, taste and the like also
compared favorably with prior art filter elements. Moreover,
manufacturing techniques for the products of this invention
require less expensive conventional plug wrap and are especially
high speed.
It will now be seen that there is herein provided a
smoke filter, and method and means for manufacturing same, which
satisfies the various objectives set forth previously, and which
provide significant advantages of a commercial nature. While
this invention has been described with reference to presently-
preferred exemplary embodiments thereof, it should be clearlyunderstood that the invention is not limited thereto, but may be
variously practiced within the scope of the following claims.
This application is a divisional application of copend- -
ing application serial No. 254,765 filed on June 14, 1976. ~
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