U.S. patent application number 11/575861 was filed with the patent office on 2008-10-16 for tobacco smoking filter or filter element with a content of adjuncts.
This patent application is currently assigned to RHODIA ACETOW GMBH. Invention is credited to Guenter Maurer, Paul Rustemeyer, Eckart Schuetz, Eberhard Teufel.
Application Number | 20080251091 11/575861 |
Document ID | / |
Family ID | 36046920 |
Filed Date | 2008-10-16 |
United States Patent
Application |
20080251091 |
Kind Code |
A1 |
Schuetz; Eckart ; et
al. |
October 16, 2008 |
Tobacco Smoking Filter or Filter Element with a Content of
Adjuncts
Abstract
A tobacco smoking filter is disclosed, with adjunets on the
surface in the form of fibres filaments or films and whereby the
drawing resistance of the tobacco smoking filter and the mass of
the adjuncts in the tobacco smoking filter meet the following
equation (I) M.sub.ad/.DELTA.p>1 mg/daPA (I), where .DELTA.p is
the drawing resistance [daPA], applied as a value calculated with a
7.8 mm filter diameter and M.sub.ad [mg] is the mass of the
adjuncts. The tobacco smoking filter comprises channel structures
and the filer material is provided as a planar material. Said
tobacco smoking filter has a low draw resistance on smoking with a
particularly good filtration effect and is relatively simple to
produce.
Inventors: |
Schuetz; Eckart;
(Gundelfingen, DE) ; Maurer; Guenter; (Neuenburg,
DE) ; Teufel; Eberhard; (Gundelfingen, DE) ;
Rustemeyer; Paul; (Gundelfingen, DE) |
Correspondence
Address: |
DARBY & DARBY P.C.
P.O. BOX 770, Church Street Station
New York
NY
10008-0770
US
|
Assignee: |
RHODIA ACETOW GMBH
Freiburg
DE
|
Family ID: |
36046920 |
Appl. No.: |
11/575861 |
Filed: |
October 6, 2005 |
PCT Filed: |
October 6, 2005 |
PCT NO: |
PCT/EP05/10775 |
371 Date: |
October 10, 2007 |
Current U.S.
Class: |
131/332 |
Current CPC
Class: |
A24D 3/16 20130101; A24D
3/048 20130101; A24D 3/10 20130101 |
Class at
Publication: |
131/332 |
International
Class: |
A24D 3/06 20060101
A24D003/06 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 6, 2004 |
DE |
10 2004 048 651.4 |
Claims
1. Tobacco smoke filters or filter elements, which are constructed
in one piece and contain fibrous filaments or films based on
polymers or polymer mixtures, which can be spun or processed into
films and contain one or more additives, wherein a) the additives
are present at the surface of the fibers, the filaments or the
films, b) the resistance of the tobacco smoke filter to the passage
of air and the mass of the additives in the tobacco smoke filter
observe the following equation (I): M.sub.ad/.DELTA.P>1 mg/daPA
(I), in which .DELTA.P.sub.7.8 is the resistance to the passage of
air (daPA), which is used as a value calculated on the basis of a
7.8 mm filter diameter, Ma.sub.d(mg) is the mass of the additives,
and c) the tobacco smoke filter has a channel structure and d) the
filter material is present as a two-dimensional formation.
2. The tobacco smoke filter of according to claim 1, wherein the
filter material is a two-dimensional formation of fibers or
filaments or folded film, the two-dimensional formation and/or the
film being smooth, folded, embossed and/or partially
consolidated.
3. The tobacco smoke filter according to claims 1, wherein the
filter material is built up from a cellulose ester.
4. The tobacco smoke filter according to claim 3, wherein the
cellulose ester is cellulose acetate, cellulose butyrate, cellulose
acetobutyrate, cellulose acetopropionate and/or cellulose
propionate.
5. The tobacco smoke filter according to claim 4, wherein the
cellulose acetate has a degree of substitution of approximately 1.5
and 3.0 and especially of 2.2 to 2.6.
6. The tobacco smoke filter according to claim 1, wherein the ratio
of M.sub.ad/.DELTA.P is more than 2 mg/daPa and especially more
than 3 mg/daPa.
7. The tobacco smoke filter according to claims 1, wherein the
additives, on the surface of the fibers, filaments or films are
particulate, and, in particular, have a particle size of less than
300 .mu.m.
8. The tobacco smoke filter according to claim 7, wherein the
particle size of the additives is less than 100 .mu.m and
especially less than 50 .mu.m and particularly less than 30
.mu.m.
9. The tobacco smoke filter according to claims 7, wherein the
particulate additives are porous additives, especially in the form
of an absorbent based on activated charcoal, metal oxides, metal
hydroxides and/or metal oxide hydrates.
10. The tobacco smoke filter according to claim 9, wherein the
metal oxides, hydroxides and/or metal oxide hydrates are those of
aluminum, silicon, titanium and/or magnesium.
11. The tobacco smoke filter according to claims 9, wherein the
porous additive is treated with active substances, especially in
the form of antioxidants, flavors and/or antimutagenic
substances.
12. The tobacco smoke filter according to claims 1, wherein the
additive, on the surface of the fibers, filaments and films, is a
filtration aid, especially in the form of organic acids, acidic
carboxylic esters of polyphenol and/or porphyrin derivatives.
13. The tobacco smoke filter according to claims 1, wherein the
particulate additives are fixed on the surface of the filter
material by means of a binder, especially with polyvinyl acetate,
polyvinyl alcohol, polyethylene glycol, water soluble esters or
ethers, starch, starch derivatives and/or cellulose esters,
especially cellulose acetate with an average degree of acetylation
of 0.3 to 1.
14. The tobacco smoke filter according to claims 1, wherein the
fibers, filaments or films of the film material contain further
additives in their interior to improve the properties.
15. The tobacco smoke filter according to claim 14, wherein the
further additives are plasticizers, marking agents, pigments and/or
stabilizers.
16. The tobacco smoke filter according to claim 15, wherein the
plasticizer within the fibers or filaments or films is present in
an amount of 5 to 15% by weight.
17. The tobacco smoke filter of according to claims 15, wherein the
plasticizer is present in the form of triacetin, ethylene glycol
diacetate and/or diethyl citrate.
18. The tobacco smoke filter according to claim 1, wherein the
fiber weight (or filament weight/resistance to the passage of air
ratio S, related to the filament funnel, is larger than about 0.7,
the S value being calculated from the formula
S=(m.sub.A/.DELTA.P.sub.7.8)/dpf [10 m/daPA] (II) in which m.sub.A
is the fiber weight (g), .DELTA.P (daPA) is the resistance to the
passage of air and dpf is the titer of the filament (dtex) and, for
the resistance to the passage of air, the value, calculated for a
filter diameter of 7.8 mm, is used, and the hardness of the
cigarette filter exceeds approximately 90 filtrona hardness.
19. The tobacco smoke filter according to claim 18, wherein the
fiber weight does not exceed 10 mg/mm of filter length and/or the
residual crimping of the filter material does not exceed the value
of 1.45, Formula (III) applying here:
I.sub.r=10,000.times.m.sub.A/(G.times.I) (III), in which m.sub.A is
the fiber weight (g), G is the total titer (g/10 exp 4.times.m) and
I is the filter length (mm).
20. The tobacco smoke filter according to claim 19, wherein the
residual crimping is between 1.05 and 1.4 and especially between
1.1 and 1.3.
21. The tobacco smoke filter of according to claims 18, wherein the
fiber weight (or filament weight)/resistance to the passage of air
ratio S, related to the filament titer, does not exceed a value of
about 2 and, in particular, has a value between 0.8 and 1.3.
22. The tobacco smoke filter according to claim 18, wherein the
fiber weight (or filament weight) is at least 4 mg/mm of filter
length and especially between 5 and 8 mg/mm of filter length.
23. The tobacco smoke filter according to claim 18, wherein the
filtrona hardness is between about 90 and 95 and particularly
between 91 and 93.
24. The tobacco smoke filter according to claim 1, wherein the
filter contains a photoreactive additive, especially in the form of
finely divided titanium oxide of the anatase type having an average
particle size of less than 2 .mu.m.
Description
[0001] The invention relates to tobacco smoke filters or filter
elements, which are constructed in one piece and contain fibers,
filaments or films based on polymers or polymer mixtures, which can
be spun or processed into films, and contain one or more
additives.
[0002] Tobacco smoke filters of the above type are known in the
art. In this connection, "in one piece" is to be understood that
the tobacco smoke filters are constructed uniformly in the
longitudinal axial direction and can be produced without further
limiting filter elements. Here there is a relevant difference from
so-called "chamber filters", for which an outwardly limited chamber
is created by an enveloping paper between filter elements of
conventional filter material, disposed at a distance from one
another in the longitudinal direction. This chamber may be filled
with additives, such as granular activated charcoal.
[0003] There has been no lack of attempts to design filter
construction, which permit a particularly efficient utilization of
porous elements. The chamber filter construction named has
disadvantages in the efficient utilization of the included
activated charcoal. Because of the limitation to the degree, to
which the chamber can be filled, and due to the comparatively
coarse granulation of the activated charcoal, a portion of the
smoke passes through that part of the chamber, which is not filled,
and, accordingly, does not come into direct contact with the
activated charcoal. The particle size of the activated charcoal
cannot be reduced at will, since this would result in an increase
in the resistance to airflow, which is not acceptable to the
smoker. The filter construction, described in the EPA-O 014 477
behaves more advantageously in this respect. For this construction,
the granular activated charcoal is scattered into a filter element
in a manner that assures an approximately homogeneous distribution
of the activated charcoal particles in the fibers or filaments of
the filter material, which, in turn, are distributed homogeneously.
Even though the formation of a bypass can be excluded in this
manner, coarsely grained additives are nevertheless required, in
order to ensure that the aforementioned particles are fixed in the
tobacco smoke filter. The disadvantages, ascribed to coarsely
grained activated charcoal, are therefore also exhibited by this
filter construction.
[0004] The following may be mentioned in connection with tobacco
smoke filters or their use and as a background for the invention,
which is described below. At their mouth end, filter cigarettes are
provided with tobacco smoke filters, which intercept at least a
portion of the combustion products of the tobacco of the cigarette
and, by so doing, prevent inhalation of the combustion products
during smoking. On the other hand, a tobacco smoke filter should
affect the taste of the tobacco smoke, so that it is evaluated
positively by the smoker. For a portion of filter cigarettes, the
tobacco smoke filter is treated with a porous, particulate
additive, which increases the filtration performance of the tobacco
smoke filter or the tobacco smoke filter elements in comparison to
a tobacco smoke filter without the particulate additives. This
effect frequently can be explained owing to the fact that the
porous additives preferentially adsorb gaseous combustion products
at their inner surface and, by so doing, reduce their concentration
in the smoke. For the most prominent representatives of this type
of cigarette filters, activated charcoal is used as porous,
particulate additive. Other tobacco smoke filters, such as those
described in the DE-A-2 658 479, contain oxides, hydroxides and/or
oxide hydrates of different metals, such as silicon, aluminum,
magnesium, iron and/or titanium. The accessibility of such porous,
particulate additives for the gaseous smoke components is of
decisive importance for their effectiveness. For example, it has
turned out the filter performance of finely divided porous
materials especially is better than that of coarser particles.
Further disadvantages of the chamber filters addressed are to be
seen therein that the cost of manufacturing them are high.
[0005] Other known filter constructions indicate possibilities of
binding also finely grained additives in the tobacco smoke filters.
U.S. Pat. Nos. 3,043,736 and 2,881,770 describe a tobacco smoke
filter consisting of a bundle of endless crimped filaments of
cellulose acetate, which has been combined into a filter rod by
enveloping paper, the individual filaments being coated with finely
divided activated charcoal. The possible devices for applying the
finely particulate additives can be divided into devices a) for
applying the additives from a suspension in an aqueous phase or a
volatile organic carrier or a plasticizer fluid, b) for blowing-on
the additives, which consist of small particles and may previously
be wetted with an adhesive or a plasticizer, c) for applying from a
latex emulsion and d) for applying the additive, in that a bundle
of filaments or threads, previously wetted with adhesive or
plasticizer, is passed through a whirled-up bed of finely divided
activated charcoal. In this respect, reference is made to the DE
127 4 946.
[0006] The tobacco smoke filters, produced according to the above
method, are distinguished owing to the fact that the filaments,
loaded with additives, are oriented preferably longitudinally and
are bound to one another alternately at statistically distributed
contact sites by means of the action of an adhesive or plasticizer,
so that essentially longitudinal, small spaces, distributed
uniformly over the filter, are created between adjacent filaments
by the flow of the tobacco smoke.
[0007] The examples listed make it clear that the tobacco smoke
filters, so produced and treated with particulate additives, have a
high resistance to the flow of air, which is similar to that of
comparison filters, in which particulate additives have not been
enmeshed. Accordingly, filters, which have a uniformly high mass of
additives as well as a low resistance to airflow, cannot be
produced according to these methods.
[0008] Alternatively, paper filters, doped with activated charcoal,
are used in tobacco smoke filters. These contain activated
charcoals of small particle size, which are bound to the paper
during the paper-manufacturing process. At the same time, during
the production of the filter material, a fabric is formed, rolled
onto bobbins and subsequently sent to the processor. The filter or
cigarette manufacturer unrolls the material from the bobbins and
forms it into a rod-shaped product, in order to consolidate it then
transversely axially in the mold part of the filter rod machine,
envelop it in paper and cut it to the ultimate length of the filter
rods. In addition, the fabric usually, but not necessarily, is
wrinkled parallel to the direction in which it runs through the
creping device, before it is shaped into a rod. With that, a
reduction in the density of the material on the one hand, and an
effect on the resistance to the passage of air through the filter
on the other, are achieved. A channel structure, in which
longitudinally aligned, channel-shaped regions of low material
density extend over a considerable portion of the filter or filter
element, is characteristic of such filters produced by folding
two-dimensional materials. These channels are bounded by filter
material of a higher material density. The comparatively low
resistance of these filters to the passage of air can be attributed
essentially to this structural property.
[0009] However, when these two-dimensional filters, which do not
consist or consist only partially of cellulose acetate, are used,
the taste of the smoke frequently is evaluated as being negative.
In addition, such filters do not exhibit the specific retention
performances for phenols or nitrosamines, which are known from
cigarette filters of cellulose acetate.
[0010] It was therefore an object of the invention to improve the
tobacco smoke filters or filter elements, which are constructed in
one piece and described above, so that the effectiveness of the
bonded, finely divided absorbents is effected as little as
possible, and, nevertheless, when a higher mass of the particulate
additives are bonded, the resistance to the passage of air is low.
Moreover, cellulose acetate, in particular, is to be used as filter
material.
[0011] Pursuant to the invention, this objective is accomplished
owing to the fact that that a) the additives are present on the
surface of the fibers, the filaments or the films, b) the
resistance of the tobacco smoke filter to the passage of air and
the mass of the additives in the tobacco smoke filter observe the
following equation (I): M.sub.ad/.DELTA.P>1 mg/daPA (I), in
which .DELTA.P is the resistance to the passage of air (daPA),
which is used as a value calculated on the basis of a 7.8 mm filter
diameter, M.sub.ad(mg) is the mass of the additives, c) the tobacco
smoke filter has a channel structure and d) the filter material is
present as a two-dimensional formation.
[0012] Within the scope of the invention, the usual fibers,
filaments and films, based on polymers or polymer mixtures, which
can be spun or processed into films, may be used. Within the scope
of the invention, the filter material preferably is a
two-dimensional structure of fibers or filaments or a film, the
two-dimensional structure and/or the film being smooth, folded,
embossed and/or partially consolidated.
[0013] It is particularly preferred if the filter material is built
up from a cellulose ester, cellulose acetate, cellulose butyrate,
cellulose acetobutyrate, cellulose acetopropionate and/or cellulose
propionate, in particular, coming into consideration as cellulose
ester. A particularly preferred cellulose acetate has a degree of
substitution of 1.5 to 3.0, especially of about 2.2 to 2.6 and,
particularly of 2.5. Within the scope of the invention or of its
realization, it has proven to be particularly advantageous to use a
tobacco smoke filter, which is described in WO 01/28369. In a
slight modification of the present invention and for the further
optimization, it is preferred that the fiber weight (or filament
weight resistance to the passage of air ratio S), related to the
filament funnel, is larger than about 0.7, the S value being
calculated from the formula
S=(m.sub.A)/.DELTA.p.sub.7.8/dpf(10 m/daPA) (II),
in which m.sub.A is the fiber weight (g) .DELTA.P (sic!!) is the
resistance to the passage of air (daPA) and dpf is the filament
titer (dtex) and, for the resistance to the passage of air, the
value, calculated for a filter diameter of 7.8 mm, is used, and the
hardness of the cigarette filter exceeds approximately 90 filtrona
hardness.
[0014] Moreover, it is regarded as preferred here that the fiber
weight does not exceed 10 mg/mm of filter length and/or the
residual crimping of the filter material does not exceed the value
of 1.45, the following formula (III) applying here:
I.sub.r=10,000.times.m.sub.A/(G.times.I) (III),
in which m.sub.A is the fiber weight (g), G is the total titer
(g/10 exp 4.times.m) and I is the filter length (mm).
[0015] The optimum residual crimping is between 1.05 and 1.4 and
especially between 1.1 and 1.3. Moreover, preferably the fiber
weight (or filament weight)/resistance to the passage of air ratio
S, related to the filament titer, does not exceed a value of about
2 and, in particular, has a value between 0.8 and 1.3.
[0016] Particularly advantageous results are achieved with the
inventive tobacco smoke filter if the fiber weight (or filament
weight) is at least 4 mg/mm of filter length and especially between
about 5 and 8 mg/mm of filter length.
[0017] With respect to optimizing the filtrona hardness, it may be
noted that this should preferably be between about 90 and 95 and
particularly between 91 and 93.
[0018] Within the scope of the invention, the additives, which are
essential for accomplishing the objectives set, are disposed on the
surface of the fibers, the filaments or the films. It is
particularly preferred here if these additives are particulate and,
in particular, have a particle size of less than 300 .mu.m and
especially of less than 100 .mu.m. It is particularly preferred if
the particle diameter is less than 50 .mu.m, a particle size of 30
.mu.m leading to particularly good results. The invention is not
subject to any significant limitation in the selection of the
particulate additives or porous additives. Someone of ordinary of
skill in the art is capable of selecting suitable additives without
any problems, these being present preferably in the form of an
adsorbent based on activated charcoal, metal oxides, metal
hydroxides and/or metal oxide hydrates, especially those of
aluminum, silicon, titanium and/or magnesium. In individual cases,
the porous additive preferably is treated additionally with active
substances, especially in the form of antioxidants, flavors and/or
anti-mutagenic substances.
[0019] The introduction of the particulate additives into the
inventive tobacco smoke filter is not limited critically.
Nevertheless, it is preferred if the particulate additives are
fixed to the surface of the filter material by means of a binder,
especially with polyvinyl acetate, polyvinyl alcohol, polyethylene
glycol, water-soluble esters or ethers, starch, starch derivatives
and/or cellulose esters.
[0020] The surface of the fibers, filaments and films may be
optimized further, as follows. For example, the additive on the
surface may fulfill the function of a filtration aid, especially in
the form of organic acids, acidic carboxylic esters, of polyphenol
and/or porphyrin derivatives. The fibers, filaments and films of
the film material or the fibers, filaments and films, from which
the tobacco smoke filters or filter elements are built up, may
contain in their interior further additives, which improve their
properties. Preferably, these are plasticizers, frosting agents,
pigments and/or stabilizers. The inclusion of plasticizers is of
particular importance. Preferably, these are present within the
fibers or filaments or films in an amount of 0 to 15% by weight and
especially of 5 to 12% by weight. Advisably, the plasticizer is
present as triacetin, ethylene glycol diacetate and/or diethyl
citrate. In addition, the inventive tobacco smoke filter may also
contain a photoreactive additive, especially in the form of a
finely divided titanium dioxide of the anatase type, having an
average particle size of less than 2 .mu.m.
[0021] A particular characteristic is given by the distinguishing
feature b) of the above-defined inventive teachings. According to
this, it is a requirement of the invention that the resistance to
the flow of air of the tobacco smoke filter and the mass of the
additive in the tobacco smoke filter adhere to the following
formula M.sub.ad/.DELTA.P.sub.7.8>1 mg/daPA (I), in which
.DELTA.P is the resistance to the passage of air (daPA), which is
used as a value calculated on the basis of a 7.8 mm filter
diameter, M.sub.ad(mg) is the mass of the additives. In particular,
it is preferred if the ratio of M.sub.ad/.DELTA.P is more than 2
mg/daPa and, in particular, more than 3 mg/daPa.
[0022] The channel structure of the claimed, one-piece tobacco
smoke filter or filter elements is a further significant
distinguishing feature of the invention. It should be pointed out
that, for a channel structure, longitudinally aligned,
channel-shaped regions of lower material density extend over an
appreciable part of the filter or filter element. These channels
are limited by the filter material of a higher material density. In
particular, this channel structure is adhered to owing to the fact
that a two-dimensional formation is used, pursuant to the
invention, as filter material.
[0023] Someone of ordinary skill in the art can, without problems
and without further additional technical information, produce the
one-piece tobacco smoke filter or the one-piece tobacco smoke
filter element. A particularly suitable method is dealt with in the
following. Here, for the production of the inventive tobacco smoke
filter tow is pulled from bales, prepared pneumatically according
to methods customary for space filters. Before the actual
activation step, a nonwoven fabric, with the highest possible
strength in the direction of the two axes of the surface, is
produced in an intermediate step, wound onto spools and acted upon
with additives. Any method, suitable for producing tobacco smoke
filters, can be used for distributing powder on a fiber surface.
The devices are particularly suitable a) for applying the additives
from a suspension in an aqueous liquid or a volatile, organic
carrier or in a plasticizer liquid for the filaments, to which, in
each case, a binder may be added and b) for blowing the additive,
consisting of small particles, onto the filaments, which may
previously be wetted with an adhesive or a plasticizer.
Alternatively or in addition, the adhesion of the particulate
additives can be ensured by a melt adhesive, which is applied
either together with the particulate additives or separately or
activated by heating briefly.
[0024] The inventive tobacco smoke filter can be produced
continuously, starting from filter rods, and cut to a limited
length. Each individual element of a length, limited in this way,
could be used by itself as a tobacco smoke filter for a cigarette.
However, preferably, it is used in a longitudinally aligned
arrangement with at least one further filter element as part of an
assembled (such as a double or triple) cigarette filter.
Preferably, a single filter element of the present invention is
used in combination with a longitudinally aligned mouthpiece
element of the usual appearance, for example, a uniform rod of
cellulose acetate fiber cable.
[0025] The advantages, which are associated with the present
invention, can be summarized as follows. It has turned out that, by
adhering to the inventive teachings, finely divided additives can
be introduced into tobacco smoke filters, and, at the same time,
contrary to the corresponding comparison product from the prior
art, a particularly low resistance to the passage of air can be
noted during smoking. It was found that a particularly high
filtration performance can be achieved with the inventive
filters.
[0026] Moreover, in comparison to the corresponding comparison
products of the state of the art, the inventive one-piece tobacco
smoke filter can be produced relatively easily. Moreover, the
expensive production of the aforementioned chamber filter from
several filter elements is omitted. It is a further advantage that,
particularly when the filter material is constructed from cellulose
acetate, the taste of the smoke is evaluated as particularly
positive. A selective retention effect with respect to phenols is
also observed.
[0027] The invention is described in greater detail below by means
of examples.
EXAMPLE 1
Preparation of an Inventive Filter
[0028] A filter tow, having the specification 2,1Y48 (with a
filament titer of 2.33 dtex and a total titer of 53,333 dtex) is
prepared on a conventional, two-step KDF drafting device of the
Hauni Company, Hamburg and sprayed with 8% triacetin. After leaving
the guide roller, the filter tow web, with a minimum width of 250
mm is introduced into a pair of heated calender rollers and
calendered with an effective line pressure of 40 kg/cm. The
profiled calender rollers have a diameter of 230 cm and a grooved
width of 355 mm and have 10 profiled grooves per cm, whereas the
other roller is not profiled. They are heated to 150.degree. C.
with a silicone oil. The grilled profile is trapezoidal with an
upper width of 0.4 mm and a depth of 0.5 miTL.
[0029] After leaving the calender rollers, the nonwoven, so
prepared, is wound on a spool. Such a nonwoven spool is unwound at
a conventional Foulard and passed through a bath, which is filled
with an aqueous suspension of activated charcoal. In so doing, the
nonwoven, directed downwards, is immersed up to 5 cm in the
suspension and then deflected upward at a guide roller. On leaving
the suspension bath, the excess suspension is squeezed off by a
pair of squeeze rollers. The squeeze rollers are driven at a speed
of 10 m/min and ensure uniform movement of the nonwoven through the
suspension. After leaving the squeeze rollers, the nonwoven is
passed through a recirculating air dryer at a temperature of
150.degree. C. The dryer has a drying segment of 4 meters and, with
that, ensures the drying of the suspension and the fixing of the
activated charcoal on the nonwoven.
[0030] Upon leaving the dryer, the nonwoven, doped with activated
charcoal, is folded into strands in a conventional commercial KDF 2
of the Korber Company, Hamburg, by being introduced into an inlet
nozzle, enveloped with paper and cut to a filter length of 126 mm.
The diameter of the filter rods was adjusted to 7.8 mm.
COMPARISON EXAMPLE 1
Preparation of an Activated charcoal Filter by Scattering Carbon
Particles into a Filter Tow
[0031] A filter tow, having the specification 2,1Y48 (with a
filament titer of 2.33 dtex and a total titer of 53,333 dtex) is
prepared on a conventional KDF 2 drafting device of the Hauni
Company, Hamburg and sprayed with triacetin. Upon leaving the guide
roller, the filter tow web with a minimum width of 200 mm is guided
through a spreader nozzle and treated pneumatically with activated
charcoal particles having a particle size of approximately 250
.mu.m. For this purpose, the activated charcoal powder is dosed
continuously with a dosing balance onto an intake connecting piece
and blown with compressed air through a pipeline to the spreader
nozzle. Advantageously, the spreader nozzle is enclosed in a box
with suction, which has openings only for the intake and discharge
of the filter tow web, in order to avoid any escape of carbon dust
into the surroundings. By matching the amount of activated charcoal
supplied to the speed of the filter tow web, the amount of
activated charcoal on the filter tow web can be adjusted very
accurately. Upon leaving the device described, the filter tow web
is folded into strands in an inlet nozzle and enveloped with paper
in a conventional commercial KDF 2 of the Korber Company, Hamburg,
at a strand speed of 50 m/min and cut to a filter length of 126 mm.
The filter rod diameter was adjusted to 7.8 mm.
[0032] The results of measuring the resistance to airflow and the
mass of the activated charcoal are summarized in the Table.
TABLE-US-00001 Activated Particle Size Charcoal mass Resistance to
Activated (mg per 21 mm flow of air Charcoal Dpf Total of filter
(filter plug) M.sub.ad/.DELTA.P (.mu.m) (dtex) (dtex) plug (daPA)
(mg/daPA) Comparison 250 2.33 53 80 131 0.61 Example 1 333 Example
20 2.33 53 80 10 8.0 333
* * * * *