U.S. patent application number 15/021198 was filed with the patent office on 2016-08-04 for tobacco smoke filter.
The applicant listed for this patent is ESSENTRA FILTER PRODUCTS DEVELOPMENT CO. PTE. LTD. Invention is credited to Elizabeth GERRINGER, Ahmad Fashihul LISAN, James REED, Kenneth TULLY.
Application Number | 20160219930 15/021198 |
Document ID | / |
Family ID | 49552537 |
Filed Date | 2016-08-04 |
United States Patent
Application |
20160219930 |
Kind Code |
A1 |
REED; James ; et
al. |
August 4, 2016 |
TOBACCO SMOKE FILTER
Abstract
A tobacco smoke filter or filter element including a
longitudinally extending core of tobacco smoke filtering material
of perimeter 14 to 17 mm; and an additive release vessel fully
enclosed within the core; wherein the filtering material is a
filamentary material having a filament denier of 5.3 or greater and
a total denier of 18,000 or less.
Inventors: |
REED; James; (Newcastle,
GB) ; LISAN; Ahmad Fashihul; (Sidoarjo, ID) ;
GERRINGER; Elizabeth; (Newcastle, GB) ; TULLY;
Kenneth; (Newcastle, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ESSENTRA FILTER PRODUCTS DEVELOPMENT CO. PTE. LTD |
Singapore |
|
SG |
|
|
Family ID: |
49552537 |
Appl. No.: |
15/021198 |
Filed: |
September 10, 2014 |
PCT Filed: |
September 10, 2014 |
PCT NO: |
PCT/EP2014/069328 |
371 Date: |
March 10, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A24D 3/062 20130101;
A24D 3/04 20130101; A24D 3/063 20130101; A24D 3/10 20130101; A24D
3/061 20130101 |
International
Class: |
A24D 3/06 20060101
A24D003/06; A24D 3/10 20060101 A24D003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 11, 2013 |
GB |
1316210.2 |
Claims
1. A tobacco smoke filter or filter element comprising a
longitudinally extending core of tobacco smoke filtering material
of perimeter 14 to 17 mm; and an additive release vessel fully
enclosed within the core; wherein the filtering material is a
filamentary material having a filament denier of 5.3 or greater and
a total denier of 18,000 or less.
2. A tobacco smoke filter or filter element according to claim 1
wherein the longitudinally extending core of tobacco smoke
filtering material is a substantially cylindrical core of tobacco
smoke filtering material.
3. A tobacco smoke filter or filter element according to claim 1
wherein the longitudinally extending core of tobacco smoke
filtering material is of perimeter or circumference 16 to 17
mm.
4. A tobacco smoke filter or filter element according to claim 1
further including a wrapper engaged around the longitudinally
extending core.
5. A tobacco smoke filter or filter element according to claim 1
wherein the filtering material is filamentary cellulose acetate
tow.
6. A tobacco smoke filter or filter element according to claim 1
wherein the filamentary material has a filament denier of 5.3 to
13, for example 5.3 to 9, for example 5.4 to 8, for example 6 to
7.
7. A tobacco smoke filter or filter element according to claim 1
wherein the filamentary material has a total denier of 9,000 to
18,000, for example 10,000 to 18,000, for example 12,000 to 17,000,
for example 14,000 to 16,000.
8. A tobacco smoke filter or filter element comprising a
longitudinally extending core of tobacco smoke filtering material
of perimeter 14 to 17 mm; and an additive release vessel fully
enclosed within the core; wherein the tobacco smoke filtering
material is cellulose acetate having a filament denier of 5.3 or
greater and a total denier of 18,000 or less.
9. A tobacco smoke filter or filter element according to claim 8
wherein the longitudinally extending core of tobacco smoke
filtering material is a substantially cylindrical core of tobacco
smoke filtering material.
10. A tobacco smoke filter or filter element according to claim 8
wherein the longitudinally extending core of tobacco smoke
filtering material is of perimeter or circumference 16 to 17
mm.
11. A tobacco smoke filter or filter element according to claim 8
further including a wrapper engaged around the longitudinally
extending core.
12. A tobacco smoke filter or filter element according to claim 8
wherein the cellulose acetate has a filament denier of 5.3 to 13,
for example 5.3 to 9, for example 5.4 to 8, for example 6 to 7.
13. A tobacco smoke filter or filter element according to claim 8
wherein the cellulose acetate has a total denier of 9,000 to
18,000, for example 10,000 to 18,000, for example 12,000 to 17,000,
for example 14,000 to 16,000.
14. A tobacco smoke filter or filter element according to claim 1
wherein the additive release vessel is a capsule, for example a
frangible capsule.
15. A tobacco smoke filter or filter element according to claim 1
wherein the additive release vessel includes additive in the form
of a flavourant.
16. A tobacco smoke filter or filter element according to claim 1
wherein the additive release vessel is of width 2.0 to 4 mm, e.g.
3.2 to 3.7 mm, e.g. 3.5 mm.
17. (canceled)
18. A filter cigarette comprising a filter according to claim 1,
joined to a wrapped tobacco rod with one end of the filter towards
the tobacco.
19. A multiple rod comprising a plurality of filters or filter
elements according to claim 1 joined end-to-end.
20. A product rod comprising a plurality of individual tobacco
smoke filters according to claim 1, abutted end to end; and a
wrapper engaged around the plurality of filters.
21. A filter cigarette comprising a filter which includes a filter
element according to claim 1, joined to a wrapped tobacco rod with
one end of the filter towards the tobacco.
22. A product rod comprising a plurality of individual tobacco
smoke filters including filter elements according to claim 1,
abutted end to end; and a wrapper engaged around the plurality of
filters.
Description
[0001] The present invention relates to tobacco smoke filters and
filter elements, for example for smoking articles such as
cigarettes.
[0002] The manufacture and use of cigarette filters containing a
breakable capsule is well-known. On breakage by the smoker prior
to, during, or after smoking, these capsules release liquid or
substances contained therein--typically flavourants--that can in
turn be transferred to the cigarette smoke whilst the cigarette is
being smoked, or into the surrounding environment after the
cigarette has been extinguished.
[0003] It is also known to provide cigarette filters in a variety
of different circumferences, typically from around 25 mm to around
14 mm. These are known as `standard`, `slim`, `superslim` and
`microslim` products as the filter circumference decreases within
this range (e.g. from around 24.5 mm, to around 23 mm, to around
16-17 mm, to around 14-15 mm respectively). However, to date, there
has been no commercial exploitation of capsule-bearing filters in
the superslim (circumference around 16-17 mm) and micro-slim
(circumference around 14-15 mm) formats. One of the issues is that
the capsule tends to occupy a relatively higher proportion of the
cross-sectional area of a superslim or microslim filter product,
resulting in an unacceptably high pressure drop (because the smoke
is channelled through a narrower conduit surround the capsule).
[0004] According to the present invention in a first aspect there
is provided a tobacco smoke filter or filter element comprising a
longitudinally extending (e.g. substantially cylindrical) core of
tobacco smoke filtering material of perimeter (e.g. circumference)
14 to 17 mm (e.g. 16 to 17 mm); and an additive release vessel
(e.g. a capsule) fully enclosed within the core; wherein the
filtering material is a filamentary material (e.g. a filamentary
filter tow) having a filament denier of 5.3 or greater and a total
denier of 18,000 or less.
[0005] Preferably, the longitudinally extending core of tobacco
smoke filtering material is a substantially cylindrical core of
tobacco smoke filtering material.
[0006] Preferably, the longitudinally extending core of tobacco
smoke filtering material is of circumference 16 to 17 mm (that is,
the filter or filter element is a superslim filter or filter
element).
[0007] The filter or filter element may further include a wrapper
(e.g. paper, plugwrap) engaged around the longitudinally extending
(e.g. substantially cylindrical) core. The wrapper may be a wrapper
of paper, for example a wrapper of an air-permeable paper.
[0008] The additive release vessel (e.g. a capsule) is fully
enclosed within the longitudinally extending (e.g. substantially
cylindrical) core of tobacco smoke filtering material. This means
that the additive release vessel (e.g. a capsule) is not visible
(to the smoker) at the mouth or buccal end of the filter/filter
element, or at the mouth end of a cigarette including a filter of
this aspect of the invention, in use. Preferably at least one end
of the longitudinally extending (e.g. substantially cylindrical)
core of tobacco smoke filtering material has a uniform appearance.
Preferably at least one end of the longitudinally extending (e.g.
substantially cylindrical) core of tobacco smoke filtering material
has a uniform appearance such that only the tobacco smoke filtering
material is visible at that end of the core (e.g. such that other
components such as additive, channels or similar are not visible at
that end of the core). A uniform end appearance (e.g. an appearance
such that only smoke filtering material is visible at that end of
the core) may advantageously be pleasing to the smoker.
[0009] The tobacco smoke filtering material of the longitudinally
extending core may be any filamentary material conventionally
employed for tobacco smoke filter manufacture. The filtering
material may be a natural or synthetic filamentary tow, e.g. of
cotton or plastics such as polyethylene or polypropylene, or
cellulose acetate filamentary tow. Preferably, the filtering
material is filamentary cellulose acetate tow.
[0010] According to the present invention in an aspect there is
provided a tobacco smoke filter or filter element comprising a
longitudinally extending (e.g. substantially cylindrical) core of
tobacco smoke filtering material of perimeter (e.g. circumference)
14 to 17 mm (e.g. 16 to 17 mm); and an additive release vessel
(e.g. a capsule) fully enclosed within the core; wherein the
tobacco smoke filtering material is (e.g. filamentary) cellulose
acetate (e.g. cellulose acetate tow) having a filament denier of
5.3 or greater and a total denier of 18,000 or less.
[0011] Preferably, the longitudinally extending core of tobacco
smoke filtering material is a substantially cylindrical core of
tobacco smoke filtering material.
[0012] Preferably, the longitudinally extending core of tobacco
smoke filtering material is of circumference 16 to 17 mm (that is,
the filter or filter element is a superslim filter or filter
element).
[0013] The filter or filter element may further include a wrapper
(e.g. paper, plugwrap) engaged around the longitudinally extending
(e.g. substantially cylindrical) core. The wrapper may be a wrapper
of paper, for example a wrapper of an air-permeable paper.
[0014] The specification of a filamentary tobacco smoke filtering
material (e.g. filter material tow) such as cellulose acetate is
described in terms of the denier per filament (dpf); total denier;
and the fibre cross-sectional shape. The filament denier is defined
as the weight in grams of 9000 metres of a single filament; the
total denier is then simply the dpf multiplied by the number of
filaments in the tow. Thus, for example, a 5Y30,000 tow describes a
material with a filament with a dpf of 5 grams per 9000 metres in
the shape of a Y, comprising 6,000 filaments giving a total denier
of 30,000 grams per 9000 metre length; a 5.2Y18,000 tow describes a
material with a filament with a dpf of 5.2 grams per 9000 metres in
the shape of a Y, comprising about 3,500 filaments giving a total
denier of 18,000 grams per 9000 metre length; and a 6.8Y15,000 tow
describes a material with a filament with a dpf of 6.8 grams per
9000 metres in the shape of a Y, comprising about 2200 filaments
giving a total denier of 15,000 grams per 9000 metre length.
[0015] The filamentary material (e.g. filamentary filter tow,
cellulose acetate, cellulose acetate tow) may having a filament
denier of 5.3 or greater, for example 5.3 to 13, for example 5.3 to
12, for example 5.3 to 9, for example 5.4 to 8, for example 6 to 7.
The filamentary material (e.g. filamentary filter tow, cellulose
acetate, cellulose acetate tow) may have a filament denier of 5.3
to 7.9, 5.3 to 7.5, for example 6 to 7.5. The filamentary material
(e.g. filamentary filter tow, cellulose acetate, cellulose acetate
tow) may having a filament denier of 5.3, 5.4, 5.5, 5.6, 5.7, 5.8,
5.9, 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2,
7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6,
8.7, 8.8, 8.9, 9. In examples, the filamentary material may have a
filament denier of 5.3 or greater, for example 5.4 or greater, for
example 5.5 or greater, for example 5.6 or greater, for example 5.7
or greater, for example 5.8 or greater, for example 5.9 or greater,
for example 6 or greater, for example 6.1 or greater, for example
6.2 or greater, for example 6.3 or greater, for example 6.4 or
greater, for example 6.5 or greater.
[0016] The filamentary material (e.g. filamentary filter tow,
cellulose acetate, cellulose acetate tow) may have a total denier
of 9,000 to 18,000, for example 10,000 to 18,000, for example
12,000 to 17,000, for example 14,000 to 16,000. The filamentary
material (e.g. filamentary filter tow, cellulose acetate, cellulose
acetate tow) may have a total denier of 15,000 to 18,000, for
example 15,100 to 18,000, for example 15,500 to 17,000, for example
15,500 to 16,000. The filamentary material (e.g. filamentary filter
tow, cellulose acetate, cellulose acetate tow) may have a total
denier of 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000,
17,000, 18,000. In examples, the filamentary material may have a
total denier of 18,000 or less, for example 17,900 or less, for
example 17,800 or less, for example 17,700 or less, for example
17,600 or less, for example 17,500 or less, for example 17,400 or
less, for example 17,300 or less, for example 17,200 or less, for
example 17,100 or less, for example 17,000 or less.
[0017] The filamentary material may be of any cross section (e.g. Y
shaped cross section, X shaped cross section, circular cross
section, the skilled person will appreciate that various cross
sections are known in the art). Filamentary material of Y shaped
cross section is preferred.
[0018] The additive release vessel may be a capsule, for example a
frangible capsule. The (e.g. frangible) capsule may include
additive in the form of a flavourant. The additive release vessel
[(e.g. frangible) capsule] may contain one or more additives, for
example a flavourant and/or a liquid, solid or other material, such
as activated carbon, e.g. to aid smoke filtration. The use of
additive containing capsules in filters is well known in the
art.
[0019] The flavourant may be any flavourant known or suitable for
use in a smoking article such as a cigarette, for example menthol,
spearmint, peppermint, fenugreek, clove etc. Preferably the
flavouring agent is or comprises menthol. The vessel (capsule) may
comprise more than one flavouring agent (and may provide blends of
different flavours, which may or may not include menthol).
[0020] The filter or filter element may include additive in the
form of flavourant [e.g. in the the additive release vessel [(e.g.
frangible) capsule], wherein the amount of additive (flavourant) is
less than 35 mg (per filter/filter element). The filter or filter
element may include additive in the form of flavourant [e.g. in the
additive release vessel [(e.g. frangible) capsule], wherein the
amount of additive (flavourant) is 5 to 30 mg, for example 7 to 25
mg, for example 10 to 25 mg, for example 10 to 20 mg (per
filter/filter element).
[0021] The additive release vessel [(e.g. frangible) capsule] may
be of width (when measured at its broadest point in a direction
across the filter, that is perpendicular to the direction in which
the longitudinally extending core extends) 2.0 to 4 mm, e.g. 2.5 to
3.9 mm, e.g. 3.0 to 3.8 mm, e.g. 3.2 to 3.7 mm, e.g. 3.5 mm. The
additive release vessel [(e.g. frangible) capsule] may include less
than 35 mg flavourant. The additive release vessel [(e.g.
frangible) capsule] may include from 5 to 30 mg, for example 7 to
25 mg, for example 10 to 25 mg, for example 10 to 20 mg
flavourant.
[0022] The filter or filter element may be of length 10 to 30 mm,
e.g. 14 to 27 mm, e.g. 17 to 25 mm.
[0023] As set out in Example 1 below, the present applicants made
superslim filters without capsules to determine minimum, maximum
and optimum tow weights for the relevant filter dimensions, and
then made corresponding filters with capsules, in order to assess
the effect of the capsules on the pressure drop. Surprisingly, the
applicants found that inclusion of a capsule in filter including a
core of a filamentary filtering material (e.g. cellulose acetate
tow) with a filament denier of 5.3 or greater (e.g. 6.8) and a
total denier of 18,000 or less (e.g. 15,000) was associated with
only a fairly small increase in pressure drop. This indicates that
filamentary filter material (e.g. cellulose acetate tow) having
filament denier of 5.3 or greater (e.g. 6.8) and a total denier of
18,000 or less (e.g. 15,000) may be particularly suited for use in
capsule-containing superslim or microslim filters.
[0024] A filter element according to the invention may be used as a
segment of a multi-segment slim filter, e.g. a dual, triple, other
multiple filter. Such filters are well known in the art. If the
filter element is used as or in a segment of a multi-segment
filter, it may be used at (or in) the mouth or buccal end segment
of the filter, or as (or in) any other segment of the filter. If
the filter element is used as or in a segment of a multi-segment
filter, the other segments may be, for example, wrapped or
non-wrapper acetate segments; segments which include particulate or
liquid additives such as activated carbon or flavours (e.g. active
acetate filter segments, flavour thread filter segments); segments
which comprise paper or nonwoven materials; other capsule-bearing
segments etc. A filter element according to the invention may be
used on its own e.g. as a single segment superslim or microslim
filter (e.g. in the same way as a monoacetate filter).
[0025] Filters of the invention may be packaged and sold for use in
Roll Your Own or Make Your Own smoking articles such as roll your
own cigarettes. The filters may be packaged in a similar way to
Pop-a-Tip.TM. filters for Roll-Your-Own (RYO) Smokers, which are
well known and available from Filtrona Filters. Pop-a-Tip
filters-type comprise a series of filters (filter tips) wrapped in
a transparent film e.g. made of BOPP or cellophane. The filters are
individually pushed (or `popped`) out of the transparent wrap by
smokers of RYO products, who then use the filter when rolling their
cigarette. According to the present invention in a further aspect
there is provided a product rod comprising a plurality (e.g. two or
more, e.g. 4-6) of individual tobacco smoke filters according to
any aspect of the invention (or a plurality of individual tobacco
smoke filters including filter elements according to any aspect of
the invention) abutted end to end; and a (common) wrapper engaged
around the plurality of filters or filter elements. The common
wrapper may be a transparent material e.g. made of BOPP or
cellophane.
[0026] In a filter cigarette according to the invention, a filter
of the invention (or a filter which includes a filter element of
the invention) is joined to a wrapped tobacco rod with one end of
the filter towards the tobacco. The filter may be joined to the
wrapped tobacco rod by ring tipping [which engages around just the
adjacent ends of the (wrapped) filter and rod to leave much of the
filter wrap exposed]. The filter may be joined by a full tipping
overwrap (which engages around the full filter length and the
adjacent end of the tobacco rod).
[0027] The filter, filter element or filter cigarette according to
the invention may be ventilated by methods well known in the art,
e.g. by use of a pre-perforated or air-permeable wrapper, and/or
laser perforation of the wrapper and, if present, tipping overwrap.
A ventilating full tipping overwrap may likewise be inherently
air-permeable or provided with ventilation holes, and in ventilated
products where both wrapper and tipping overwrap are present
ventilation through the overwrap will usually (and preferably) be
in register with that through the wrapper (e.g. plugwrap).
Ventilation holes through the filter wrapper, or through a tipping
overwrap, or through both simultaneously, may be made by laser
perforation during filter or filter cigarette production, as is
well known in the art.
[0028] According to the invention in a further aspect there is
provided a multiple rod comprising a plurality (e.g. 2, 4, 6 etc.)
of filters (or filter elements) as described above and/or herein
integrally joined end-to-end in a mirror image relationship.
[0029] The present invention will now be illustrated with reference
to the attached drawings in which:
[0030] FIG. 1 is a view of a tobacco smoke filter according to an
example of the invention;
[0031] FIG. 2 is a view of the tobacco smoke filter of FIG. 1 with
part cut away to show the interior of the filter;
[0032] FIG. 3 shows the capability curve for the 5.2Y18000 tow, as
described in Example 1 below; and
[0033] FIG. 4 shows the capability curve for the 6.8Y15000 tow
described in Example 1 below.
[0034] The filter 1 shown in FIG. 1 (and FIG. 2) includes a
longitudinally extending substantially cylindrical core 2 of
tobacco smoke filtering material of perimeter 16.8 mm and length 27
mm. (In actual fact the core 2 has circumference 16.8 mm, because
the cylindrical core 2 is of circular cross-section.) The filtering
material is a 6.8Y15,000 filamentary tow of filamentary cellulose
acetate. Filter 1 also includes a wrapper 3 of plugwrap which is
engaged around the longitudinally extending core 2 and held in
place by a lapped and stuck seam, as is well known in the art.
[0035] Filter 1 also includes an additive release vessel in the
form of a flavour containing frangible capsule 5 which is fully
enclosed within the cylindrical core 2; the filtering material
completely encloses the capsule. This is perhaps best seen in FIG.
2 (which shows a cutaway view of the filter and capsule) but the
position of the capsule 5 within the core 2 is also shown in FIG. 1
by means of the dotted line 5a. The additive release vessel is a
spherical capsule 5 having diameter 3.5 mm which comprises a
breakable outer shell 6 of gelatin or similar, which encloses
menthol containing liquid 7. Such frangible or breakable spherical
capsules 5, which include flavourant therein, and their methods of
manufacture, are well known in the art.
[0036] Methods for making capsule containing filters are well
known. It is well known to make longitudinally extending filter
rods from filamentary filter materials such as cellulose acetate
tow by drawing the cellulose acetate filamentary tow from a source,
gathering the longitudinally advancing tow (e.g. by passing through
a nozzle), and advancing the gathered/compressed tow through a
garniture where the newly formed longitudinally extending rod of
filtering material is wrapped in a plugwrap, and the plugwrap fixed
in place by a lapped and stuck seam. The longitudinally advancing
rod may be cut into individual filters, or, more usually, into
multiple rod comprising a plurality (e.g. 2, 4, 6 etc.) of filters.
This method may be adapted to make capsule containing filters by
including a machine which inserts capsules (such machines are well
known) into the process. In one such machine, (spherical) capsules
5 are held in a stack and fed consecutively into the longitudinally
advancing filamentary cellulose acetate tow as it is gathered, so
the advancing tow is gathered and compressed around capsules 5 as
it passes through the nozzle and into the garniture. The resulting
longitudinally advancing rod which includes capsules is cut into
filters/rods in the usual manner.
[0037] The filter of FIG. 1 may be joined to a wrapped tobacco rod
(not shown) with one end of the filter towards the tobacco, by
methods well known in the art. The filter may be joined to the
wrapped tobacco rod by ring tipping, which engages around just the
adjacent ends of the wrapped filter 1 and rod to leave much of the
wrapper 3 exposed, or joined by means of a full tipping overwrap
which engages around the full length of the filter 1 and the
adjacent end of the tobacco rod.
EXAMPLE 1
Trials for the Manufacture of Superslim Capsule Filters
[0038] Multiple length `mono` filter rods were made by methods
known in the art. Each multiple length filter rod comprised a
longitudinally extending substantially cylindrical core of
filamentary cellulose acetate of length 108 mm and a circumference
of 16.8 mm. It will be appreciated that this rod is a multiple rod
which may be cut down to four filters of length 27 mm (a so called
"4 up" rod). Two different cellulose acetate filter tows were
used--5.2Y18000 and 6.8Y15000. As is well-known, the first number
(5.2 or 6.8) refers to the filament denier, Y refers to the
filament cross-sectional shape and the second number (15000 or
18000) refers to the total denier of the tow.
[0039] The above mono filters/filter rods, without capsules, were
assessed to determine the minimum, maximum and optimum tow weights
for these filter dimensions--enabling the plot of a so-called `tow
capability curve`. Such curves are well-known to those skilled in
the art. Having determined these three points for the `mono` rods
(and also having confirmed that these values were consistent with
those predicted by a standard modelling program `virtual tow
selector`), corresponding rods with 4 evenly spaced capsules
(spherical shape, diameter 3.5 mm) per 108 mm rod, one per filter
in the rod, were made to assess the effect of the capsules on the
pressure drop of the filters.
[0040] Tables 1 and 2 below show capability against pressure drop
results for `mono` filter rods and capsule containing filter rods
including 5.2Y18000 tow (Table 1) and 6.8Y15000 tow (Table 2)
following the assessment, and these data are also shown graphically
in FIGS. 3 and 4.
[0041] The minimum point was determined as the tow weight which
gave a 1 mm recess in the finished rod (i.e. the tow `sprang back`
to give a dished end to the finished filter/rod after cutting). The
maximum point was determined by the tow weight which yielded a
co-efficient of variation in pressure drop of around 6%--higher
variability values are generally considered unacceptable. Tow
weights were input into the virtual tow selector program to
determine the `capability percentage` shown in the Tables. The
5.2Y18000 tow item provided a capability range of -1 to 36%. The
6.8Y15000 tow item yielded a capability range of 0 to 70%.
TABLE-US-00001 TABLE 1 5.2Y18000 Tow Results Tow Mean Tip PD
Circum- Weight PD PD Capa- Capsule Capability Rod ference (g/100
(mm/ CoV bility Increase Level Type (mm) rods) rod) (%) (%) (mm)*
Low Mono 16.71 24.60 375.6 3.8 -1 Capsule 16.80 24.60 479.2 3.6 -1
33 Optimum Mono 16.85 25.88 399 3.4 9 Capsule 16.95 25.88 535 5.3 9
38 Maximum Mono 16.99 28.32 451 7.3 36 Capsule 17.17 28.32 584.8
6.4 36 27.2
TABLE-US-00002 TABLE 2 6.8Y15000 Tow Results Tow Mean Tip PD
Circum- Weight PD PD Capa- Capsule Capability Rod ference (g/100
(mm/ CoV bility Increase Level Type (mm) rods) rod) (%) (%) (mm)*
Low Mono 16.78 21.04 206.5 3.8 0 Capsule 16.81 21.04 267.7 4.3 0 15
Optimum Mono 16.83 23.92 288.3 5.3 34 Capsule 16.86 23.92 363.7 5.6
34 21 Maximum Mono 16.98 26.60 338.4 9.8 70 Capsule 17.17 26.60
429.8 8.8 70 18.9
[0042] Pressure drop is a key parameter in filter design. Decision
criteria for available pressure drop range would be typically based
on those data points that yielded a co-efficient of variation of 6%
or less from the tow items. The available pressure drop range from
the capsule filters using these tows was accordingly found to be
270-380 mm water gauge for 6.8Y15000 tow and 480-550 mm water gauge
for 5.2Y18000 tow. Use of these tows outside these ranges, may
yield poorly running or performing product (i.e. which is difficult
to manufacture or has inferior performance). * Corrected for
circumference differences and 4 tips per rod.
[0043] As expected, the addition of the capsule caused an increase
in the pressure drop of the rod. The 5.2Y18000 tow saw an average
pressure drop increase of 33 mm per tip (based on results for a 108
mm/4-up rod) whilst the average tip PD increase for the 6.8Y15000
tow was only 18 mm.
[0044] Thus, unexpectedly, the applicants found that inclusion of a
capsule in filter including a core of a filamentary filtering
material (e.g. cellulose acetate tow) with a filament denier of 5.3
or greater (e.g. 6.8) and a total denier of 18,000 or less (e.g.
15,000) was associated with only a fairly small increase in
pressure drop. This indicates that filamentary filter material
(e.g. cellulose acetate tow) having filament denier of 5.3 or
greater (e.g. 6.8) and a total denier of 18,000 or less (e.g.
15,000) may be particularly suited for use in capsule-containing
superslim or microslim filters.
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