Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates to a fibre-containing
material web, especially a paper web, for the manufacture of
filter rods which can be subdivided into filter plugs fcr
tobacco products, the web being provided with a multiplicity
of zones which run in the longitudinal direction and have a
highly fibrillated structure and/or unconnected crac~-like
orifices and also with zones, located between the former zones,
having a denser structure and/or rib-like deformations, but the
cohesion of the material web being preserved. ~aterial webs of
this type, and especially paper webs, are already extensively
used for the manufacture of filter plugs for cigarettes and may
be manufactured by the processes of U.5.~a~èn~s ~, 293t~4~, 2~40
~995481, 31615S~, 31~90~ 22~gO, 3383 449 . Filter
rods produced from such webs using the conventional tow
machines are satisfactory for most purposes in respect of their
draw resistance and the separation effect, which i3 proportional
to the latter, in respect of undesired substances in tobacco
smoke, and the mechanical strength o~ the filter sticks is also
adequate. For some types of filter plugs demanded by the
cigarette manufacturers, it is necessary, in order to ensure
the desired, considerably higher draw resistance, to pass the
particular paper webs, after drying, between a pair of so-called
knurling rollers, the surfaces of which are provided with
pyramid-shaped points, these rollers destroying again, in
particular, the denser zones having the rib-like deformations
in the paper web. The even greater fibrillation achieved as a
- 2 - ~
- result does indeed give the desired higher draw resistance but
at the same time effects a reduction in the mechanical strength
of the particular filter sticks. Another method for increasing
the draw resistance of such paper webs is described in ~I.S,
Patent ~o. 3.383.852 and is based on the replacement of the said
~nurling rollers by a pair of rollers having a smooth surface
which, in particular, results in the rib-like deformations beiny
pressed together and enables the draw resistance to be increased,~
however, this is again at the expense of a reduced mechanical
strength of the filter sticks produced.
According to one aspect of the present invention there
is provided a fibre-containing material web for the manufacture
of filter rods which can be subdivided into filter plugs for
tobacco products, the web having a rib-like structure comprising
a multiplicity of first zones which run longitudinally of the
we~ and have a highly fibrillated structure and second zones,
located between the first zones, having a denser structure than
the first zones, the material web also having impressed therein
a design consisting of closely adjacent impressions which are
in the form of lines of strokes and extend transversely over
at least part of the longitudinal zones to provide the rib-like
structure running in the longitudinal direction with consecutive
indentations spaced longitudinally of the web.
Another aspect of the present invention provides a
2S process for the manufacture of a material web wherein a
material web provided with a multipliclty of zones of different
'72~
alternating dense and less dense structures running in the
longitudinal direction is ~oved in the said longitudinal
direction and, at successive intervals, is pressed together,
for a short time in each case and only in linear regions
running transversely to the material web, a multiplicity of
consecutive permanent indentatlons being produced at least
on the denser longitudinal structures with the longitudinal
structures being retained unde~stroyed between the consecutive
indentations.
~ further aspect of the invention provides apparatus
for the manufacture of a material web suitable for use in the
manufacture of filter rods, such apparatus containing a holdi.ng
frame with two rollers, the axes of which are arranged parallel
to one another, means for adjusting the position of the first
roller in respect of its distance from the second roller, at
least one of the two rollers having, on its surface, projecting
ribs which form a uniform design in the form of strokes that
run at least substantially parallel to the axis of the roller,
and a controllable drive for the two rollers whereby the two
rollers are rotatable with equal surface speeds.
A fourth aspect of the invention provides a filter
rod for filters for tobacco products, which comprises a
packing of a paper web which has been gathered together
transversely to its longitudinal direction and has a
multiplicity of zones which run in the longitudinal direction
and have a highly fibrillic structure and/or unconnected
-- 4 --
'
,
~' ' ' :: '
.
crack-like orifices, and also zones, located between the
former zones. having a denser structure and/or rib-like
deformations, which packing additionally has successive closely
adjacent impre~sions and indentations in the axial direction,
these impressions and indentations extending transversely to
the longitudinal zones.
The present invention is explained in more detail
below in various illustrative embodiments, with the aid of
the accompanying drawings, in which:
Figure 1 is a schematic representation of a longitudinal
section of part of an illustrative embodiment of equipment
provided with embossing rollers according to the teachings
of the invention;
Figure 2 is a schematic horizontal projection of the
equipment according to Figure 1 without the upperr~ller,
Figures 3 and 4 are each a sche~atic cross-section
through a paper web, b~fore entry into the equipment according
to Figures 1 and 2 and, respectively, along the plane A-A after
the web has left the equipment,
Figure 5 is a schematiccross-section through a
further illustrative embodiment of the equipment,
Figure 6 is a photograph of the surface of an
illustrative embodiment of the paper web according to the
invention,
Figure 7 is an eight-fold enlargement of the paper
web shown in Figure 6 on a scale of 8:1,
-- 5
Figure 8 is a photograph of a filter rod formed
from a paper web according to Figures 6 and 7, the covering
of the filter rod belng partly removed,
Figure 9 is a diagram of the draw resistance as a
function of the breadth of raw paper web used for various
filter rods,
Figure 10 is a diagram of the depth of penetration
when hardness measurements are carried out on various filter
rods,
Figures 11-15 each show a view of the surface of
different illustrative embodiments of embossing rollers for
the equipment of Figure l;
Figures 16 and 17 show respectively an axial
longitudinal section and the side view of an illustrative
em~odiment of the embossing rollers,
Figure 18 is a schematic representation of an
illustrative embodiment of an installation for the manufacture
of a roll of paper web according to the invention'
Figure 13 is a schematic representation of an
illustrative embodiment of an installation for the manufacture
of the paper web according to the invention and processing
it into filter rods,
Figure 20 is a schematic representation of an
illustrative embodiment of an installation for the manufacture
of a paper web according to the invention from a roll of
plain paper, and
.. . .
, ,, ' , ' : :
,
' ' ' :
' ' . ' ' : ',:,- ':
.
,
Figure 21 is a schematic representation of an illus-
trative embodiment of an installation for the manufacture of a
paper web according to the invention from a roll of plain paper
and processing the web to form filter rods.
The principle of the process for the production of
the present material web is initially illustrated in more detail
with the aid of Figures 1 to 4. It is assumed that a paper
web 10 of a known type is available which has a multiplicity
of rib-like deformations 12, which run parallel in the longi-
tudinal direction, and thus in the direction of movement 11,
and are of a denser fibre structure, and also longitudinal
zones, located between the former zones, having a highly fibril-
lated structure and a multiplicity of unconnected longitudinal
slits. Paper webs of this type which are, for example, 15 to
30 cm wide are already used in considerable quantities for the
manufacture of filter rods in so-called tow machines, in which
the paper web which passes through is gathered together in
the transverse direction, covered with smooth paper and shaped
to give a continuous cylindrical tow of, for example, 8 mm
diameter, from which the filter rods for example 80 mm in
length, are then manufactured by subdividing. These filter
rods are subsequently fed to one of the conventional cigarette
machines where they are further subdivided into filter plugs
and attached to a tube of tobacco, which has already been
covered, by means of a the so-called tip strip, in order to
produce filter cigarettes.
As shown in the Figures, this paper web 10 is first
- ) )
fed to equipment which, according to Figures 1 and 2, es~entially
consists of the two embo~sing rollers 13 and 14 which are
arranged with their axes parallel and with the distance between
the axes being adjustable. In the illustrative embodiment
shown in Figures 1 and 2, the two rollers have projecting
ribs 17 and 18 on their qurfaces 15 and 16 respectively, these
ribs extending around the entire surface of the rollers and
running para~el to the axes of the rollers. The two rollers
( 13 and 14 have a cross-section with projecting ribs that are
absolutely identical and the rollers are driven together in
such a way that they rotate at the same surface speed. They
are adjusted relative to one another so that the tips of the ribs
of the upper roller 13 and of the ribs of the lower roller 14
are precisely opposite one another in the gap between the two
rollers. The paper web 10 is moved through this gap and for~
this reason the distance between the rollers 13 and 14 is
adjusted so that the fore-parts o~ the ribs 17 and 18. which
are opposite one another, do not come into contact~ A distance
of about 0.1 - 0.2 mm between opposite ribs 17 and 18 must be
2~ maintained.
As indicated schematically in Figures 1 and 2, the
paper web 10, and especially its longitudinal ribs 12, are
provided, on passing through the gap between the rollers 13
and 14, with closely adjacent impressions 19 which, in this
case, extend transversely over all of the longitudinal zones
and, in particular, give corresponding indentations in the
.
longitudinal ribs 12. Whilst the paper web 10 still has the
cross-section indicated schematically i~ Figure 3 and a total
thicXne3s between the upper and lower longitudinal ribs o~,
for example, 0~8 mm when it enters into the gap between the
pair of rollers 13 and 14, the paper web has been preRsed
virtually completely flat along the impressions 19, as is
shown schematically in Figure 4 along the cutting plane A-A.
Of course, the cross-section of the paper we~ remains vixtually ~
( unchanged in the spaces between adjacent i~pressions 19 and
thus corresponds approximately to Figure 3. In the present
illustrative embodiment, the rollers 13 and 14 have diameters
of about 180 mm, and the ribs 17 and 18 respectively, which run
parallel to the central axis of each roller, project about
3 mm beyond the particular surface 15 or 16 respectively of
the roller and have the cross-section of an equilateral
triangle and a distance from centre line to centre line of about
2 mm. In order to ensure accurate true running after the
mechanical production of the rollers, the surfaces of the
rollers are ground, so that the tips of the ribs 17 and 18 are
about 0.2 mm wide.
In the illustrative embodiment of the equipment
according to Figures 1 and 2, it must be ensured that, in
each case, the fore-parts of the ribs 17 and 18 are precisely
opposite one another in the gap between the two rollers 13 and
14 and this requires high precision during manufacture of the
rollers and in respect of the drive and adjustment thereof.
.
_ g _
An illustrative embodiment of the equipment for the manufacture
of the present paper web which is less demanding in this
respect and is preferred is shown in Fiyure 5. In this case
an upper roller 13 having ribs 17, projecting above the ~urface
15, of the same type of construction as in the illustrative
embodiment according to Figure 1 is used. However, this
roller 13, provided with ribs, is opposite a roller 20 which
has a smoothly ground surface 21. The gap between the two
rollers, or between the particular rib 17 and the smooth
surface 21, can be adjusted in this case also and is preferably
set to about 0.15 to 0.2 mm. The paper web 10, which passes
through, is provided with impressions 19 in this case also,
but these impressions are produced only by the upper roller
13 and its ribs 17. When the two rollers 13 and 20 are
correctly set to a gap width oI 0.15 to 0.20 mm, it is, however,
possible to achieve virtually the same advantageous results,
which are explained in even more detail below, as in the case
( of a paper web which is provided with such indentations
on the upper and lower side at the same time, using equipment
according to Figure 1.
As already mentioned above, paper webs which have
rib-liXe deformations running in the longitudinal direction and
zones, located between the latter, having a multiplicity of
unconnected crack-like orifices are already used for the
manufacture of filter sticks ~or tobacco products. Paper webs
which have such longitudinal ribs at intervals of about 1 mm have
-- 10 --
.. .. . .
'' ' ' ~'" :: .
~ ? ~
proved particularly approriate for this purpose. If a paper
web of this type is provided, by means of equipment according
to Figure 5, with impressions, in the form of strokes, which
run transversely to the longitudinal ribs and follow one another
at intervals of approximately 2 mm, this gives the paper web
shown in Figure 6. The unconnected orifices which run in the
longitudinal direction ll and the longitudinal ribs extending
between the latter can clearly be seen, as can the impressions
which run transversely thereto, that is to say vertic~lly to
the direction of the arrow 11. The resulting structure can be
seen even more clearly from Figure 7, which is an eight fold
enlargement of Figure 6. In these two photographs, the white
paper web was, in each case, placed on a black background and
photographed from above in reflected light, so that the black
portions in each case represent orifices in the highly fibril-
lated paper web. However, despite the existing fibrillations,
which is necessary for the desired strong filter effect, a
paper web of this type has considerable strength in the longi-
tudinal direction ll, which is necessary if it is to be proces-
sed in tow machines to manufacture filter rods. Despite themultiplicity of unconnected longitudinal slits, however, the
transverse cohesion of the paper webs is also ensured, which is
also important for processing in a tow machine.
It must, however, be pointed out that the paper web
2$ according to Figures 6 and 7 has, despite the existing fibril-
latio which is important for a good filter action, a stable
structure
-- 11 --
.
which is retained substantially unchanged even after the
deliberate gathering together in the tl~SVerse direction on
entry into a tow machine for the manufacture of filter rods.
This can be seen, for example, from Figure 8 which shows a
photograph of a filter rod manufactured from a paper web
according to Figures 6 and 7, for the photograph, the outer
covering of the cylindrical filter rod of 8 mm diameter
was cut away in order to render the structure of the packing
visible. Despite the fact that the paper web has been gathered
together in an irregular manner and deliberately trans~ersely
to its longitudinal direction, the zones running in the
longitudinal direction, which have a highly fibrillated
structure, and unconnected crack-like orifices can be seen.
Moreover, the packing shows a multiplicity of additional
impressions and indentations which follow one another in the
axial direction and are closely adjacent and which run
transversely to the longitudinal zones. As a result of these
indentations, a multiplicity of transverse connections between
~he individual channels running in the longitudinal direction
for the passage of smoke are thus provided when cigarette filters
of this type are used. At the same time, however, the streams
of smoke in the individual longitudinal channels are slowed
down and deflected by the walls of the indentations and this
results in an increase in the so-called draw resistance of
the filter rods, which i~ advantageous, as will also be
explained further below.
- 12 -
.
-
' '. ' ~ ,
:.
In addition to this desired increase in the draw
resistance, the indentations, however, also effect a stiffening
of the paper web in the transverse direction, caused by the
rib-like deformations 12, which run in the longitudinal
direction, being pressed together, as is shown schematically
in,Figure 4. This stiffening in the transverse direction is
also desirable and, in the packing of the filter sticXs,
effects a certain radial pressure outwards and thus increases
the mechanical strength of these sticks against compression
from the outside.
It will initially be demonstrated that a paper web
treated in accordance with the present process gives a
technical advance in respect of the draw resistance which can
be achieved in filter rods. It is to be taken into account
that, in the present range of draw resistances, the increase
therein is synonymous with an increase in the retention,
that is to say the separation, of undesirable smoke constituents
of the tobacco smoke.
EXAMPLES
The measurements given below were carried out on
filter rods which had all been manufactured from longitudinally
- grooved and fibrillated paper webs made from a smooth raw
paper from Messrs. TENER0/Switzerland on machines available
commercially under the name DIC0( ) at a speed of about 150-200
m~minute. The draw resistance of the filter rods was measured
in a commerc:ially available apparatus which it is not necessary
to describe since it i9 only a comparison of the results which
is important here.
A and B - So-called "slightly creped" paper webs
were manufactured from a raw p'~per weighing about 31 gramme~
per m and of different widths, and filter rods 8.0 mm in
diameter and 84 mm in length wlare produced from these webs on
a tow machine of conventional construction. The draw resistance
in mm of WC (water column) was measured for lOO filter rods
in each case, and the average value was derived from these
measurements and plotted in the diagram of Figure 9 as a
function of the width of the raw paper used. In the case
of the curve designated A, while the paper webs were passed
through a station according to Figure 5, the gap between the
rollers 13 and 20 was set so wide that the ribs 17 did not
come into contact with the paper web. On the other hand, in the
case of the curve designated B, the gap between the ribs 17 of
the roller 13 and the ribs 18 of the roller 14 was in each case
( reduced to about 0.15 mm, that is to say the paper web was
provided, in accordance with the present process, with a
multiplicity of impressions and indentations running transversely.
However, the particular setting of the machine in respect of the
speed, and depth of crepe and the like was retained unchanged.
C and D - In this case highly creped paper webs, that
is to say paper webs provided with rib-likè deformations as deep
as possible and highly fibrillated longitudinal zones between
the deformations, obtained from a raw paper weighing 35 grammes/m2
- 14 -
and of different widths, were used in order to manufacture
8.1 x 66 mm filter rods. The average value of the draw
resistance of laO filter rods in each case was plotted in the
diagram. Curve C shows this draw resistance as a function
of the width of the uncreped paper for filter rods made
from paper webs without emb~ssed indentations and, on the
other hand, D shows the corresponding values for filter rods
made from paper webs having such indentations.
It can be seen from a comparison from curves A and
B that the treatment of the paper web in accordance with the
present process in an equipment described above with the aid
of Figure 5 results in an increase in the draw resistance,
corresponding to the vertical distance between curve B and
curve A. This increase in the draw resistance is about 60%
relative to curve A. In the case of the filter rods
corresponding to curve B, thus, an approximately 6~/o greater
retention of the undesired components of the smoke can be
expected, after the filter rods have been sub-divided into
filter plugs for cigarettes, than in the case of the filter
rods or filter plugs corresponding to curve A.
The advantages of the paper webs treated in
accordance with the present process can also be demonstrated
from curves A and B of Figure 9 by the horizontal distance
becween the two. If, for example, filter rods having a draw
resistance of about 135 mm of WC are to be manufactured, a
width of raw paper of 220 mm is usually required for this purpose
- 15 -
according to curve A. When the present process is used, on
the other hand, a width of raw paper of about 190 mm sllffices,
as curve B shows, to ensure the same draw resistance of the
filter rods. The saving of a 30 mm width of raw paper, or of
about 13 % compared with the previous consumption, is an
appreciable lowering in the cost of such filter rods since
the costs thereof are essentially determined by the consumption
of raw paper.
A comparison of curves A and B thus shows the
considerable superiority of the paper webs treated in
accordance with the present process for the manufacture of
8.0 x 84 mm filter rods having a relatively low draw resistance.
Filter rods of this type are extensively used in the manufacture
of filter cigarettes. However, the paper webs treated in
accordance with the present process can also advantageo~sly
be used in the production of filter rods which have to meet
considerably greater demands, as curves C and D in the
( diagram according to Figure 9 show.
These curves C and D relate to filter rods 8.1 x 66 mm
in size, for which, despite the shorter length, substantially
higher draw resistances of about 150 mm of WC are required
than in the case of the 8.0 x 84 mm filter rods of curves A
and B. Accordingly, wider raw paper webs must be used and a
deeper longitudinal grooving with as high as possible a degree
of fibrillation of the paper web must be provided in order,
according to curve C, to obtain a draw resistance of the
~. :
magnitude demanded without the use of the present process.
However, if the paper web~ for filter rods according to
curve C are additionally provided, in accordance with the
present process, with impressions running transversely, the
draw resistance~ according to.curve D are obtained. In
this case, the increase in the draw resistance is about 10~/o
compared with~curve C, that is to say it is much greater
than in the case of E~ample A-B above and, of course, this
is due to the fact that, with the more strongly pronounced
rib-like deformations of the longitudinally grooved paper web
in this case, the indentations running transversely thereto
also change the paper structure to a greater degree than is
the case with the less deeply longitudinally grooved and
deformed paper webs of Example A-B. The width of raw paper
which would have to be provided in order to manufacture filter
rods having a draw resistance of about 150 mm of WC is, as
shown by the prolongation of curve D, drawn as a broken line,
( . only about 200 mm when the present process is used, compared
with the width of about 270 mm required hitherto according
to curve C. The saving in raw paper would, in this case, then
be about 26 %, that is to say twice as great as in the case of
~xample A-B.
As already mentioned above, a significant factor is
that, in the case of all measures for increasing the draw
resistance of filter rods, too severe an impairment of the
mechanical strength thereof towards a radial pressure exerted
- 17 -
rt`~
vertically to the axis of the filter rod i~ highly undesirable.
This mechanical strength or haxdness can be measured with
commercially available devices. such as are described, for
example, in a publication by J. Flesselles in "Beitrage zur
S Tabakforschung", page 528-538, Number 8, Volume 3, 1966. ~n
explanation is not required here since, in the present context,
it is only the comparison of different values of the depth
of penetration of a loaded stamp in the radial direction into
such filter rods which is of interest.
In the diagram of Figure 10, this depth of penetration
is plotted for the filter rods according to Examples C and
D described above. This depth of penetration is the less the
harder the packing of the filter rods. Accordingly, the depth
of penetration for filter rods according to Example C produced
from 280 mm wide raw papèr webs is less than that for filter
rods produced from 250 mm wide raw paper webs. A hardness
corresponding to depths of penetration of less than about 0.4
mm is regarded as acceptable for the further processing of
the filter rods. As Figure 10 shows, the depth of penetration
is virtually unchanged when paper webs treated in accordance with
the present process are used for the manufacture of the filter
rods according to Example D, despite the fact that, as explained
above, the draw resistance of these filter rods has been
increased by about 100 %, compared with that according to
- 18 -
Example C. Apparently, the indentations running transversely
to the longitudinal axiq of the filter effect an increased
rigidity of the packing in the radial direction, especially in
the longitudinal ribs of the paper web.
The advantage of a constant hardness despite an
increase in the draw resistance, which is achieved with filter
rods manufactured with paper webs treated in accordance
with the present process, can be particularly appreciated
if the negative influence on the hard~ess of the rods
which results from the conventional measures for increasing
the draw resistance is taken into account for comparison. Such
comparison measurements F, F and G under the same
above mentioned test conditions as for the hardness measurements
according to C and D are plotted in Figure 9. 8.1 x 66 mm
filter rods were measured and in each case these were
manufactured from paper webs produced from 290 mm wide raw
paper webs and having extensive creping, that is to say
grooving as deep as possible.
-- 19 --
~ '2 ~
Hardness measurement E: Without additional measures
-
to increase the draw resistance, the filter rods showed a
draw resistance of 120 to 130 mm of WC and a depth of
penetration of 0.19 to 0.27 mm, as plotted in the diagram of
Figure 10.
Hardness measurement F: The same longitudinally
grooved paper web as in Example E was additionally fed, after
longitudinal grooving had been effected, in the dry state
through a so-called knurling station where it passed between
two rollers which were pressed together and rotated about
horizontal axes, the surface of the rollers being provided
with a dense knurling consisting of a multiplicity of pyramid-
shaped protuberances. This knurling station has already
been described in more detail in the ~S. Paten~s Nos. 2~95 481,
3,1~9, 0~ and is a known means of effecting further
fibrillation of the paper webs in order to increase the
draw resistance of the filter rods manufactured therefrom.
It is possible, by this means, to manufacture filter rods
having a draw resistance of about 180 to 200 mm of ~C,
but the hardness diminishes, corresponding to a depth of
penetration of about 0.55 to 0.70 mm. as shown in Figure 10.
This softness of filter rods produced from paper webs
"knurled" in this way is regarded as a disadvantage during
further processing of these rods, but hitherto no other
method for achieving the desired increase in the draw
- 20 -
resistance was known.
Hardness measurement G: The longitudinally grooved
paper web described in Example E was additionally passed, in
the dry state between two smooth cylindrical rollers which
S rotated about parallel horizontal axes and the gap between
which had been narrowed to a slit of 0.1 to 0.2 mm. This
pressing equipment has already~ been described in the
~ ,S, Patent No. 3383852 as a means of
increasing the draw resistance of filter rods produced from
paper webs "flattened" in this way. It is possible to manufacture
filter rods having a draw resistance of 190 to 210 mm of WC
from the paper webs of Example E prepared in this way, but
these rods have a greatly reduced hardness corresponding to
the depth of penetration of 0.84 to 1.04 mm indicated in
Figure 10. Filter rods which have such poor mechanical
hardness values are difficult to use in further processing.
Thus, the present process is the only method known
nitherto for altering the structure of paper webs having
closely adjacent zones which extend in the longitudinal
direction and have a highly fibrillated and weakened
structure, as well as zones, located between the former zones,
having rib-like deformations, so that a substantial
increase in the draw resistance of filter rods manufactured
therefrom is obtained with virtually no reduction. or only a
slight and tolerable reduction, in the mechanical hardness
of these filt:er rods.
- 21 -
The paper webs described above for the filter rods
according to Examples B and D and also the paper webs shown
in Figures 6 and 7 were all treated in accordance with the
present process using equipment corresponding to Figure 5. For
this treatment, a roller 13 with ribs 17 running parallel to
the axis of the roller and ext:ending over its entire length
was used. The surface of the roller 13 is shown schematically
in Figure 11. However, for the present process and the
~'~ advantages, described above. of the correspondingly processed
paper web, it is not necessary for the ribs to extend without
interruption over the entire length of the roller. On the
contrary. it is possible. to use a roller according to Figure
12 with which each of the individual ribs has interruptions.
However, a requirement is that these interruptions in the
individual ribs are not all at the same point but that
the gaps mutually overlap. so that the required homogeneity
of the paper web in respect of the indentations running
transversely to the longitudinal ribs is ensured.
In the embossing rollers according to Figures 11 and
12, all of the ribs run parallel to the axis 22. This is not
absolutely essential for the present purpose, on the contrary
it suffices if the ribs are aligned at least approximately
parallel to the axis of the rollers and. therefore. embossing
rollers according to Figure 13. which have ribs corresponding
to a wavy line. can be used. Ribs which slope slightly
towards the axis of the roller are also admissible, as
- 22 -
~"`6~
shown in Figures 14 or 15. However. in all forms of such
embossing rollers it is important that the direction of the
ribs deviates only relatively slightly ~rom that of the axis 22
of the rollers. since it is important that the indentations in
the form of lines or strokes in the rib-like deformations,
running in the longitudinal direction, of the paper web are
aligned transversely to the longitudinal zones because it is
only then, after the paper we~ has been gathered together to
form a cylindrical filter rod, that these indentations assist
in maintaining a certain rigidity of the packing in the
radial direction, which prevents a reduction in the mechanical
hardness of such filter rods.
When designing the embossing rollers for the present
process, it is important that the longitudinally grooved paper
web provided with indentations running transversely ensures
homogeneous packing of the filter rods or of the filter plugs
formed therefrom by subdividing. Since. for some applications.
for example in the case of so-called double or triple filters.
the filter rods are sub-divided into relatively short filter
plugs having an axial length of only 5 to 6 mm. care must be
taken to ensure adequate homogeneity of the packing even in
these short filter plug sections. Because of this demand,
it is a condition that the indentations in the form of lines
or strokes which are embossed transversely into the paper
web are arranged relatively closely behind one another in the
axial direction, so that at least two or more such indentations
- 23 -
6 4' ;~
are present even in the above mentioned short filter plug
sections. A distance between successive indentations in the
axial direction of about 1.5 to 2 mm has proved to be
appropriate. so that even a short filter section only 5 to 6 mm
in length contains at least two to three of these indentations
running transversely. If the distance between successive
indentations were to be greater than 2 mm, it could happen,
as can be seen from Figure 8, that, in a short filter piece
only 6 mm in length. the packing has two or only one of these
indentations, which could result in considerable divergencies
in the draw resistance from one filter to another. It is
also appropriate to make the cross-section of the individual
rib 17 in an embossing roller 13 of this type relatively
narrow, so that the tip ~ of these ribs does not have a width
greater than about 0.2 to 0.3 mm, even after the embossing
roller has been ground. In this way it is ensured that the
indentations running transversely in the axial direction
of the filter stic~ have a width which is small compared with
the distance between two successive indentations, as can be
seen from Figure 8.
In Figures 1 and 5, the ribs 17 and 13 respectively
are drawn with flat and sharp-edged tips. This embodiment
is advantageous because it is then possible to grind the
surface of each of the finished embossing rollers coaxially to
its axis of rotation befora it is installed in the particular
embossing station, in order to ensure that the distance of
0.15 to 0.20 mm between opposite tips of the ribs 17 and
18 (Figure 1), or between the tips of rib 17 and the
opposite cylindrical surface 21 (Figure 5), which is required
for the present process, is maintained even when the two
interacting rollers are rotated. If even only one of the
two rollers were to be untrue by more than 0.01 mm relative
to its central axis, this would result, because of the
changing gap width between the two rollers during one
revolution of the particular roller, in indentations of
varying depth in the paper web, and this would result in
corresponding differences in the draw resistance of the
filter rods manufactured therefrom. In practice, a means
of checking that the two interacting rollers of an embossing
station of this type run true is first to provide a thin
metal foil or a metalised paper web with corresponding
longitudinal grooving and then to pass the foil or we~
through the gap between the two interacting rollers, since
the design produced by the indentations on the wèb surface
can then be clearly seen on the surface of a material web
of this type and can be checXed in respect of uniformity.
The rollers provided with ribs on the surface, which
are used ln the present process, can usually be manufactured
by milling the desired design of ribs into a roller having a
smooth surface. Since, however, embossing rollers of this
type are subject to a certain wear in operation and have to be
replaced after the surface has been ground several times, since
- 25 -
- ' .
2~
the width of the.particular t~ps of the ribs become~ greater
after every grinding, an embodiment of the ~mbossing rollers
~ccording to Figures 16 and 17 has proved useful4 In this
case, the embossing roller consists of a thick-wailed tube
23, onto which individual rings 24 are pushed, the rings being
secured against movement in the direction of the axis 22 by
a stop ring 25 at each end of the carrier tube 23. The
surfaces of the individual ring 24 are provided with the
particular desired rib design and can be exchanged relatively
easily and replaced when worn without the carrier tube 23 and
its bearings having to be replaced. An embossing roller
of the construction shown in Figures 16 and 17 is, however,
suitable only for an illustrative embodiment of the embossing
station according to Figure 5. in which it interacts with a
cylindrical roller having a smooth surface. miS is because
it is then immaterial whether the surface designs on consecutive
rings 24 coincide or are out of phase with one another.
Of course, it is also necessary to grind over the surface of
an embossing roller provided with embossing rings 24 of this
type after the roller has been assembled, and for this purpose
it suffices mutually to secure the individual rings against
twisting by axial pins with holes of appropriate size on the
sides of the rings which face towards one another. It is
possible to manufacture the embossing rings 24 on conventional
machine tools without difficulty and an embossing roller of
the construction shown in Figures 16 and 17 is cheaper both to
- 26 -
-
manufacture and to maintain in continuous operation than is
an embossing roller consisting of only one piece.
In an embossing station for carrying out the pre~ent
process it can be appropriate, as will also be explained
S further below. to provide heating for the embossing rollers.
Accordingly. in the illustrative embodiment of the embossing
rollers according to Figures 16 and 17, the grooves 26 are
provided in the jacket of the carrier tube 23 parallel to the
axis 22 of the roller, these grooves holding appropriate
electrical heating elements 27. These heating elements 27
are then connected, in operation, via rotating slip rings and
stationary brushes with a corresponding current source. which
appropriately can be regulated. If desired, however. a
carrier roller of this type can also be heated by providing
electrical heating elements in the inner space of the
carrier tube 23. which elements do not rotate with the tube
and can then be connected via a hollow axle supporting the
embossing roller for rotation. It is also possible to
provide internal heating of this type using other means,
thus. for example, using super heated steam or gas.
According to the present process, fibre-containing
material webs, and especially paper webs which have a multiplcity
of zones running in the longitudinal direction and having a
highly fibrillated structure and/or unconnected orifices,
and also zones, located between the former zones, having a
-~-denser structure and/or rib-liXe deformations, can be
- 27 -
.
.~ . .
.
,
,, ' ~' : .
.
~ -
considerably improved so that filter rods manufactured
therefrom have more advantageous properties, Paper webs
of the said type, wound to give so-called coils about 90 cm
in diameter and at most 30 cm in width, are known and are
supplied to filter factories or cigarette manufacturers for
use in the manufacture of filter rods. ~he installations
according to ~igures 18 and 1~ can serve to improve coils of
this type in accordance with the present proce~s.
In the installation shown schematically in Figure 18,
the longitudinally grooved paper web 31, which is to be
treated, is drawn off from the particular coil 30 and fed through
an apparatus 33 before it is fed to the embossing station 34.
The apparatus 33 serves to condition the paper web 31, that
is to say-either to remove moisture from the paper if this has
too high a water content, or slightly to moisten the paper
web if this should be too dry. Since, in some cases,
for example when transported by sea or when stored in a
tropical climate, the coils 30 tend, because of their high
absorbency, to undergo a rise in the moisture content of the
paper, a drying installation 33 is appropriate in some cases.
It can then also be desirable to warm the interacting rollers
35 and 36 of the embossing station 34, as has already been
described above. On the other hand, it has been found that in
some cases long term storage of coils 30 in a dry store room
effect too great a drying out of the paper web 31, so that it
is then appropriate to moisten the paper web somewhat as it
. - 28 -
:
'
,` .f~
passes through the apparatus 33, for example by spraying with
a fine spray of water or by other known means.
The embossing station 34 contains the two interacting
rollers 35 and 36. of which. for example, the roller 35 is
provided as the embossing roller and has ribs on its surface,
while roller 36 has a smooth cylindrical surface. The
embossing station 34 ls arranged in such a manner that the
distance between the rollers 35 and 36 can be precisely and
reproducibly set, for example by an arrangement in which the
bearings of the roller 35 are supported in sliding guides in
the holding frame in the embossing station 34 and can be raised
or lowered using fine-threaded screws. The two rollers are
jointly set in rotary motion by the drive 37 and specifically
are set in motion so that the surface speed of the roller 36
precisely corresponds to the speed of the tips of the ribs
on the roller 35. It must be possible to regulate the drive
37 so that the desired throughput speed ~r the paper web 31
can be set. In the case of paper webs of the type described
?bove with the aid of Examples A to ~, a throughput speed of
the paper web 31 of up to 250 m/minute is possible without
difficult-y. If necessary, however, the speed can be raised
to more than 400 m/minute. At these speeds it may be
appropriate to provide the shaft for the run-off of the coil 30
with a braking device of the type customary in the paper
industry.
- 29 -
~' :
~ 6~
The paper web which issues from the embossing
station 34 and which now has a design of closely adjacent
impressions in the form o~ lines or strokes which extend
transversely over at least part of the longitudinal zones,
so that, in particular, the rib-like deformations running
in the longitudinal direction have successive indentations
in the longitudinal direction, subsequently passes to a
wind-up unit 38 where it is wound up, after passing beneath
- ~ the guide roller 39, in the direction of the arrow to give
a coil 40. The wind-up unit 38 is connected via the shaft
41 to the drive 37 and can be of known construction, so that
a more detailed description is not necessary. An
advantage of the paper web 31 which issues from the embossing
station 34, that is to say a paper web processed in
1~ accordance with the present process, is that the embossed
design in no way effects a reduction, but rather effects an
increase. in the mechanical tear strength of the paper web in
both the longitudinal and the transverse direction.
Accordingly, it is possible without difficulty to wind up
_ 20 ~he paper web. processed in this way, at high speed to give a
co,l 40, which can then be supplied to the consumers, and there
further processed. in the same way as indicated above in
respect of the coil 30.
In the installation shown schematically in Figure 19,
the paper web 31 is fed to the embossing station 34 in the
same way as described above but in this case the embossing
, - 30 -
p
qtation is provided with a drive 41 which can be controlled
electronically. The paper web which issues from the embossing
station 34 is first fed past the guide roller 42 to the tension
measuring device 43 and passes from here directly into the
feed funnel 44 of a tow machine 45 of conventional construction
for the direct manufacture of filter rods. In the tension
measuring device 43, which is indicated only schematically,
the longitudinal tension of the paper web passing through is
monitered in a known manner, for example by means of a balance
arm which has two deflection pulleys at the end and which can
be turned to a greater or lesser extent in the indicated
direction of the arrow depending on the actual tension of
the paper web passing over the deflection pulleys. Such
devices are generally known and do not need to ~e described in
1'- more detail. Depending on the degree to which the particular
balance arm is turned, an electrical correction signal is
- fed from this tension measuring device 43 via the line 46 to
the drive 41, where it is used to change the drive speed for
the embossing station 34 until the throughput speed of the
paper web corresponds to that through the tow machine 45. The
drive of this tow machine 45 is connected, for example, to
a tacho generator, which supplies a signal vla line 47 to the
drive 41. where this signal is compared with a signal from a
similar tacho generator fitted to the embossing station 34.
Electronically controlled drives 41 of this type are generally
- known and do not need to be described in more detail. The
- 31 -
' ' ' ' ~ ' ~
signals on lines 46 and 47 and also the tension measuring
device 43 ensure that the embossing station 34 and the tow
machine 45 work synchronously. that is to say that the paper
web 31 passes at a constant speed and with a constant
longitudinal tension through the embossing station 34 and the
tow machine 45.
It should be point~d out that even when commercially
available tow machines45 are used, the paper web 31 is
gathered together, when it runs into the funnel ~4. in a
completely irregular manner in the transverse direction to give
a cylindrical tow which, after it has been covered with a paper
tape, is subdivided into filter rods. Despite this
deliberate gathering together, each filter rod has a highly
homogeneous packing. as can be seen. for example. from Figure 8,
which shows a filter rod which was manufactured using a tow
machine of this type with a speed of the paper web of more
than 200 m/minute. This homogeneous packing results not
only in very slight divergencies in the draw resistance of
such filter rods but also, after the filter rcds have been
-subdivided into-filter plugs. in a good appearance of the cut at
the end surface without undesired large pores being visibLe.
The installat~ons according to Figures 20 and 21 can
also advantageously be used to manufacture the material webs
having a design of adjacent impressions in the form of lines or
strokes extending transversely over at least part of the
longitudina:L zones and having successive indentations in the
- 32 -
longitudinal direction, especially in the rib-like deformations
of the paper web. In this case. for example, a smooth paper
web weighing 30 - 40 grams/m is used as the starting material
and. depending on the grooved paper webs. provided with
indentations, to be manufactured, this web has a width of about
20 - 30 cm. Smooth paper webs of this type used as starting
materials are designated as raw paper and are commercially
available in the form of raw paper rolls, usually having a
~` diameter of 70 - 90 cm.
In the installation according to Figure 20, the
smooth paper web 51 is withdrawnfrom a raw paper roll 50 and
passes first through a moistening installation, consisting,
in this case, for example of a water bath 52, in which a
rotating roller 53 is partially immers2d. The thin film of
water adhering to the surface of this roller 53 suf~ices to
moisten the paper web 51 which is pressed against this
surIace by means of a roller 54 made of elastic material,
for example of rubber. The moistened raw paper we~ then
passes to a so-called grooving or longitudinal creping station
consisting of-the three driven rollers 55, 56 and 57. A
creping station of this type is described in detail in the
-- U s~ Patent ~o. 3 ~66 3~8 Each of the
creping rollers 55, 56 and 57, which are made of metal,
has on its surface a multiplicity of annular ribs which are
arranged close to one another and have an approximately
rectangular cross-section and a width of about 0.3 mm, the
'
~ J~ ~
distance between consecutive ribs being, for e~ample, 0.7 mm.
The lower roller 55 and the upper creping roller 57 can be
finely adjusted in respect of their distance from the central
creping roller 56, so that the annular ribs of the lower and
the upper creping roller in each case engage in the grooves
between adjacent annular ribs of the central creping roller
56 without the side flanks of the annular ribs engaging with
one another coming into contact with one another. As is
indicated schematically in Fiyure 20, the moistened, and
therefore pliable, paper web first passes into the slit
between the creping rollers 55 and 56, then remains in contact
with the fore-parts of the annular ribs of creping roller 56
for the period of half a revolution and is subsequently
taken over by the tips of the annular ribs of creping
roller 56 for the period of half a revolution and subsequently
taken over by the tips of the annular ribs of creping roller
57 and withdrawn vla the deflection pulley 5~3. me
paper web 59 issuing from this grooving station containing
the creping rollers 55, 56 and 57 then has a multiplicity of
20 zones which run in the longitudinal direction and have a
highly fibrillated structure and/or unconnected crack~like
orifices, and also has zones, located between the former
zones, having a denser structure and/or rib-like deformations,
the structure being determined by the adjustable depth to
~5 which the creping rollers 55 and 57 engage in the central creping
- ~^ roller 56.- The paper web structured in this way, which is
still moist, is then fed via the guide roll 60 to a drying
.. installation 61. in which the moisture content of the paper web
- 34 -
.
2~
is virtually completely eliminated. The dry paper web then
passes into an embossing station 34 which contains the
interacting rollers 35 and 36, as has already been explained
in more detail above with the aid of Figure 18. A drive 63
is provided for rotating the rollers 53 and 5~ of the
moistening station, but this drive is connected to the drive
64 of the creping rollers 55, 56 and 57 and to the drive 6S of
the embossing rollers 35 and 36 and ensures that the paper
web 51 is always under a slight tension in the longitudinal
direction.
The paper web 62 which issues from the embossing
station and has been provided with a design consisting of
closely adjacent impressions and successive indentations in the
longitudinal direction can eith~r be wound up to coils or
further processed direct to filter rods. In the first
mentioned case, the paper web 62 is fed to a wind-up unit 38
of the type already described above for the installation
according to Figure 18. This wind-up unit 38 is coupled via
a shaft to the drives 65, 64 and 63.
Since, according to experience, a relatively large
number of coils 40 can be produced from a raw paper roll 50
using a wind-up unit 38, this wind-up unit 38 is in the present
case appropriately to be so designed that it is possible.
a~ter the production of a coil 40. to remove this
coil and to continue winding up the next coil without the
advancing m~vement o~ the paper web 62 being interrupted or it
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' - ' ''' ` - ' ~' ' -
2;~
being necessary to reduce the operating speed of the incltallation
according to Figure 20. Wind-up apparatuses o~ this type are
known and do not need to be described in any more detail. On
the other hand. however, it is also possible to process the
paper web 62 which issues from the embossing station 34 direct
to filter rods and for this purpose the paper web is-fe~, via
an interconnected tension measuring device 43, of the type
described above with the aid of Figure 19, direct to the feed
{`` funnel 44 of a tow machine ~5 of conventional construction.
In this case also provision must be made, as explained above
with the aid of Figure 19, for synchronisation between the
tow machine 45 and the drive parts 63, 64 and 65 of the
installation according to Figure 20.
A preferred illustrative embodiment of an installation
for the manufacture of a paper web is shown in Figure 21, and
this installation is also intended for processing a raw paper
roll 50. In this case t however, it is necessary to use a
raw paper which can be processed in a longitudinal grooving and
creping station consisting of the creping rollers 55. 56 and 57
wi.thout prior moistening. Raw papers of this type are
commercially available and, after passing through the creping
station, can be fed direct to an embossing station 34 containing
the embossing rollers 35 an~ 36. where they are provided with
an embossed design and a multiplicity of successive indentations
in the long:itudinal direction, as has been described above with
.. the aid of Figures.18 and 19. In a manner similar to that
- 36 -
shown in Figure 19, the paper web issuing from the embossing
station 34 is here fed vla a guide roll 42 and vla an inter-
connected tension measuring device 43 direct to the feed fun-
nel 44 of a tow machine 45 of conventional construction. Since
the raw paper web 51 is not moistened, a drying apparatus of
the type used in the installation according to-Figure 20 is
also not necessary. If desired, an electronic control device
66 for synchronisation between the drive of the tow machine
45 and the drives 64 and 65 can be provided. In an installa-
tion corresponding to Figure 21, very high throughput speedscan be achieved for the paper web 51 and the maximum production
capacity of the tow machine 45 which is used can be fully uti-
lised. Speeds of the paper web of 400 m/minute and more have
already been achieved in operation.
When the paper web produced in the installations
according to Figure 19 and Figure 21 is processed immediately
in a conventional tow machine, the possibility also exists of
providing the particular tow machine with a correspondingly
more powerful drive and of mechanically coupling the appara-
tuses to be driven, of the installation according to Figure 19
or Figure 21, to the drive of the tow machine. It is then
necessary merely to provide commercially available and adjus-
table gearings between the drive shafts and the corresponding
stations, such as those available commercially, for example,
under the name VIP control gears.
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: . , :
.' ~ -
In the installations accordlng to Figures 20 and 21,
it can be advantageous to provide both the creping rollers 55,
56 and 57 and the embossing rollers 35 and 36 with heating,
as, for example, has already been described a~ove with the aid
of Figures 16 and 17. The longitudinal grooving and creping
stations which consist o~ three rollers as (and are of the
type) indicated in the installations according to Figures 20
and 21 are indeed advantageous but can also be replaced by
corresponding stations of simpler construction in which, in
each case, the upper roller 57 is omitted and the paper web 51
is passed only through the slit between the creping rollers
55 and 56 and behind these is withdrawn directly from the
creping station. so that the de1ection rolls 58 and 60 are
omitted. Simpler grooving and creping stations of this type
consisting of only two rollers are especially advantageous
when it is not necessary to provide particularly deep grooving
and rib-like deformations in the particular paper webs.
,~ A check was also carried out on the filter rods.
manufactured in accordance with the Examples A to D illustrated
above in.order.to de~ermine whether the homogeneity of the
packing of such filter rods is influenced in any way by the
~ ressions and indentations produced accordlng to the :pre-ent
p.~cess. For this purpose., when manufacturing the filter
rcds in each case 100 pieces from the exit of the particular
tow machine were numbere,d in sequence and examined to determine
the draw resistance. It-was found that the deviations of
r~ r~
the draw resistance from the average value thereof were less
than + 5 %, which was within the limits of tolexance usually
demanded for such filter rods. It is significant that
8~1 x 66 mm filter rods of t:he above mentioned Examples C
5 and D weighing about 65 grams per 100 piece~ and having a draw
resistance of 340 mm of WC + S % could not be manufactured
hitherto from paper webs by other means without the hardness
showing inadmissibly low values.
In the above mentioned illustrative embodiments,
the material webs, the process for their treatment and their
use has been explained in particular with the aid of suitable
paper webs. However, it should ~e pointed out that it is
also possible to use, in place of these paper webs, flat and
paper-like fibre webs of a different composition if these are
suitable for provision with corresponding structures in the
longitudinal direction and for receiving an embossed design
~ consisting of impressions running transversely and successive
indentations in the longitudinal direction.
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