U.S. patent number 3,596,663 [Application Number 04/828,835] was granted by the patent office on 1971-08-03 for ventilated smoking article.
This patent grant is currently assigned to Lorillard Corporation. Invention is credited to Chase W. Lassiter, Frederick J. Schultz.
United States Patent |
3,596,663 |
Schultz , et al. |
August 3, 1971 |
VENTILATED SMOKING ARTICLE
Abstract
The admission of outside air to a tobacco smoke filter is
enhanced by providing a corrugated wrapper around the filter plug,
thereby to define a multiplicity of passages for conducting air
admitted through the tipping paper over a relatively large portion
of the surface of the filter plug.
Inventors: |
Schultz; Frederick J.
(Greensboro, NC), Lassiter; Chase W. (Greensboro, NC) |
Assignee: |
Lorillard Corporation (New
York, NY)
|
Family
ID: |
25252865 |
Appl.
No.: |
04/828,835 |
Filed: |
May 29, 1969 |
Current U.S.
Class: |
131/336 |
Current CPC
Class: |
A24D
3/043 (20130101) |
Current International
Class: |
A24D
3/04 (20060101); A24D 3/00 (20060101); A24d
001/04 (); A24f 013/06 () |
Field of
Search: |
;131/10,1A,9,198,198A,15B |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
269256 |
December 1882 |
Bourgeois |
3396733 |
August 1968 |
Allseits et al. |
3490461 |
January 1970 |
Osmalon et al. |
|
Foreign Patent Documents
|
|
|
|
|
|
|
240,650 |
|
Sep 1962 |
|
AU |
|
668,052 |
|
Aug 1963 |
|
CA |
|
938,902 |
|
Oct 1963 |
|
GB |
|
Primary Examiner: Medbery; Aldrich F.
Assistant Examiner: Pitrelli; J. F.
Claims
We claim:
1. A smoking article comprising an elongated body of tobacco, a
filter mass in end-to-end relation to the tobacco body, a separate
wrapper of air-permeable material surrounding and directly engaging
the filter mass, and a tipping paper surrounding the air-permeable
wrapper and a portion of the tobacco body and secured to them to
join them together, the tipping paper having means overlying the
air-permeable wrapper for admitting air to the filter air-permeable
wrapper, and the air-permeable wrapper being corrugated to increase
the permeable surface area thereof to facilitate conducting air
admitted through the tipping paper to the filter mass.
2. A smoking article according to claim 1 wherein the means for
admitting air through the tipping paper comprises at least one
generally circumferential row of spaced-apart perforations
overlying the filter mass, and wherein the number of corrugations
in the air-permeable wrapper corresponds generally to the number of
such perforations in the row.
3. A smoking article according to claim 1 wherein the corrugations
in the air-permeable wrapper range from about 10 to about 60 per
inch in number and have an overall depth in the range of from about
0.01 inch to about 0.06 inch.
4. A smoking article according to claim 1 further comprising a
mouthpiece in end-to-end relation to the filter mass.
5. A smoking article comprising an elongated body of tobacco, a
filter mass in end-to-end relation to the tobacco body, a wrapper
of porous paper surrounding the filter mass and a tipping paper
surrounding the paper wrapper and a portion of the tobacco body and
secured to them to join them together, the tipping paper having at
least one generally circumferential row of perforations overlying
the filter mass and the paper wrapper, and the paper wrapper being
corrugated generally lengthwise of the filter mass with
corrugations in the range of from about 10 to about 60 per inch in
number and having an overall depth of from about 0.01 inch to 0.06
inch thereby to define a multiplicity of passages for conducting
air admitted through the tipping paper to the filter mass, the
number of corrugations in the wrapper corresponding generally to
the number of such perforations in the row.
Description
BACKGROUND OF THE INVENTION
This invention relates to tobacco smoke filters of the ventilated
type and, in particular, to ventilated filters for use in
cigarettes.
A relatively recent development in the cigarette industry is the
so-called ventilated filter. A ventilated filter may be defined as
a filter which is constructed in a manner such that outside air is
drawn in through the filter and blended with the smoke for
admission to the smoker's mouth. The ventilated filter makes it
possible to use a higher density filtering medium for removal of
greater quantities of smoke while not reducing the draw that the
smoker expects.
The usual form of ventilated filter comprises one or more rows of
tiny holes in the tipping paper located in a region overlying the
filter plug. Ordinarily, the filter plug in both conventional and
ventilated filters, is enclosed in a paper wrapper, and in the case
of ventilated filters, the wrapper is either perforated or is
formed of a porous paper so that air admitted through the small
holes in the tipping paper can pass through the wrapper to the
filter plug.
It is apparent that ventilated filters of the construction
described above provide a relatively high restriction to the entry
of air to the filter. First of all, the admission of air is limited
to the holes through the tipping paper. Secondly, by reason of the
tight wrapping of the tipping paper around the filter-plug wrapper
and the wrapper around the filter plug, the admission of air is
limited to a relatively small portion of the surface area of the
filter plug, such portion of the surface area of the filter plug,
such portion being not much greater than the total area of the
holes.
SUMMARY OF THE INVENTION
There is provided, in accordance with the invention, a ventilated
filter that significantly reduces the restriction of the passage of
air to the filtering medium. More particularly, a ventilated
filter, according to the invention, comprises a filter plug, which
may be fibrous or particulate material or may be a composite or
combination of fibrous and particulate material, and will usually
have a porous filter wrapper around it. A tipping paper is wrapped
around the filter plug and a portion of the tobacco body of the
cigarette to join the filter plug to the cigarette body. The
tipping paper is constructed to admit air to the filter plug, such
as by the provision of tiny holes through it in a region overlying
the filter plug. In accordance with the invention, a significant
increase in the passage of air from the tipping paper holes into
the filter plug is afforded by providing a corrugated inner wrapper
between the filter plug and the tipping paper. The corrugations
provide a multiplicity of passages adjacent to the filter plug and
in communication with the air inlet holes in the tipping paper so
that air entering through the perforations is spread over a
relatively large area of the filter plug and is communicated over a
considerably increased surface area of the filter plug. Thus, the
invention makes it possible to lower the pressure drop at the exit
end of the filter, as compared to essentially the same filter
construction without a corrugated inner wrapper, or to provide the
same pressure drop with a less restricted airflow to the filter,
thus enabling a denser filter medium to be used.
DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention, reference may be made
to the following description of exemplary embodiments, taken in
conjunction with the figures of the accompanying drawings, in
which:
FIG. 1 is a pictorial view of a cigarette having the improved
ventilated filter, portions of the components of the cigarette
being broken away more clearly to show the construction;
FIG. 2 is a pictorial view of a cigarette having the improved
ventilated filter and also provided with a built-in mouthpiece,
portions again being broken away;
FIG. 3 is an end cross-sectional view taken through the filter plug
section of the cigarettes of either FIG. 1 or FIG. 2, the view
being on an enlarged scale relative to FIGS. 1 and 2 and being
taken generally along the plane represented by the lines 3-3 in
FIGS. 1 and 2; and
FIG. 4 is a further enlarged end sectional view of a segment of the
filter.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
The embodiment of FIG. 1 comprises, of course, a cylindrical rod 10
of tobacco encased within a paper wrapper 12 and constituting the
body of the cigarette. In end-to-end relation to one end of the
tobacco rod 10 is a filter plug 14, which may be any appropriate
smoke filter medium. The drawings show a fibrous medium. Today's
conventional fibrous filter plugs are manufactured with a paper
wrapper (not shown), and for a ventilated filter, the filter plug
wrapper is made of porous paper or a paper formed with
perforations. For purposes of the following description any
reference to the filter plug will mean the filter plug and its
wrapper, if it has one.
The filter plug 14 is enclosed within an inner band or wrapper 16
of a material that is permeable to air either by virtue of a
relatively porous structure or by the formation of perforations
through a relatively nonporous closed structure. A preferred
material for the inner wrapper 16 is a porous paper having the
following specifications:
---------------------------------------------------------------------------
Thickness 0.05 mm. Density 27--33 g/m.sup.2 Greiner Porosity 1.9
sec/50 cc. air.
__________________________________________________________________________
The filter plug 14 and the wrapper 16 are attached to the cigarette
body 10 with a conventional tipping paper 18 which encompasses the
entire filter plug and overlaps a portion of the cigarette
body.
The embodiment of FIG. 2 is the same as the embodiment of FIG. 1
except for the lengths of the filter plug 14a and the inner wrapper
16a and the inclusion in end-to-end relation at the smoking end of
the cigarette of a mouthpiece 20. The mouthpiece may be a
cylindrical plastic extrusion formed with an internal structure
providing support for the cylindrical body, and may, for example,
be of the construction described as shown in U. S. Pat. No.
3,396,733. The inner wrapper 16a is wrapped around both the filter
plug and the mouthpiece and serves to join them together for
handling as a composite unit in tipping machinery.
The filter structures of the embodiments of both FIGS. 1 and 2
provide for the admission of air into the filter and thence to the
smoker's mouth by, first of all, conduction of air through the
tipping paper 18 by way of a multiplicity of small holes 22 spaced
circumferentially around the tipping paper 18 in a region overlying
the filter plug 14 (or 14a). The number and size of the holes is
established so that a desired draw through the cigarette, with due
consideration for the pressure loss of the smoke passing through
the filter, is obtained. In other words, the filter plug may have a
pressure loss in excess of that which would provide a desirable
product, from the smoker's standpoint, and the perforations provide
for the admission of air to the filter and the flow of air with the
smoke to the smoker's mouth, the airflow compensating for the
increased pressure drop across the filter.
In accordance with the invention, the air drawn in through the
holes 22 when the cigarette is smoked is enabled to pass more
readily into the filter plug material by forming corrugations in
the inner wrapper 16 prior to assembling it onto the filter plug.
The corrugations can be produced in various ways, such as by
passing the strip for the wrapper paper between two grooved or
screw-threaded rollers. The depth and pitch of the corrugations in
the paper is controlled by the geometry of the forming rollers and
the pressure applied to them. When threaded rollers are used, one
has a right-hand thread and the other a left-hand thread, and they
are rotated in opposite directions so that the surfaces of both
move with, and in fact, feed the paper through them. The number of
corrugations is, of course, controlled by the number of grooves or
threads on the forming rollers and may range from about 10 to about
60 per inch. The depth of the corrugations may range from about
0.01 to 0.06 inch and is related somewhat to the pitch of the
corrugations.
The pitch of the corrugations is desirably such that the number of
corrugations approximates the number of holes through the tipping
paper so that most of the holes will be exposed to an open area
between the points of contact between the tipping paper 18 and the
wrapper 16. However, the corrugations should not have a pitch equal
to the number of ventilated holes, since equality in that respect
would present a risk of all ventilation holes being covered by the
outer loops of the wrapper in some cigarettes produced.
As is apparent from FIG. 4., particularly, the corrugations provide
a multiplicity of generally lengthwise airspaces running the length
of the wrapper and in communication with the outside air through
the ventilation holes 22. Thus, air drawn through the holes is
distributed along the passages and flows through the porous or
perforated wrapper 16 over a relatively large area of the surface
of the filter plug. The opportunity for air to pass relatively
freely into the filter plug is consequently greatly enhanced, as
compared to the conventional construction in which a layer of paper
overlying the filter plug closely engages the filter plug surface
and is closely engaged by the tipping paper. The net effect of such
closely engaged layers of wrapping material is a relatively
nonporous laminate, whereas the interposition of the corrugated
wrapper opens the structure and spreads the air over a much larger
area of the filter plug.
In addition to providing an increased surface for the air to enter
the filter, the corrugations of the wrapper increase the porosity
of the paper material itself by an opening up of the fiber
structure in the process of forming the corrugations. The
corrugating process involves a significant stretching of the paper
in a direction transverse to the corrugations. Therefore, this
additional factor of increased porosity of a corrugated wrapper
further enhances the freedom of entry of air into the filter.
It should be mentioned that the corrugations in the wrapper 16 do
not afford any opportunity for channeling or bypassing of smoke
along the corrugations. The end of the filter wrapper 16 is an
end-to-end engagement with the end of the cigarette body wrapper
12, and therefore the ends of the air passages constituted by the
corrugations of the wrapper 16 are closed off.
Tests have been conducted to determine the contribution of the
corrugationed wrapper to a ventilated-type filter structure. The
tests were made on control cigarettes and sample cigarettes, the
controls and the samples being of identical construction except
that the samples incorporated a plain (uncorrugated) wrapper of the
same material around the filter plug. The cigarettes were tested on
conventional mechanical smoking machines, and the pertinent
physical properties and the results of the smoking tests are set
forth in table I below.
One series of tests involved smoking the cigarettes with the holes
taped closed so as to provide a measure of the degree of similarity
between the controls and samples apart from the ventilation
feature. It is apparent from the results that the controls and
samples were quite similar. With the holes open, however, the draw
was improved, and the amounts of tar and nicotine were
substantially lower, as compared to the results obtained when the
holes were taped. Moreover, the tests showed clearly that the draw
was improved and tar and nicotine were significantly reduced in the
samples, as compared to the controls, thus demonstrating that the
invention provides material improvements in draw, tar and
nicotine.
Samples A and B1 included corrugated filter plug wrappers made of
paper having the specifications given above corrugated by passing
through rolls having 24 threads per inch and a thread depth of
0.027 inch urged together with a nip pressure on the paper of 12
lbs./inch. Sample B2 had a wrapper of the same paper corrugated on
the same equipment but with a nip pressure of 13 lbs./inch and thus
sample B2 had a slightly greater depth of corrugation than samples
A and B1. ##SPC1##
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