U.S. patent application number 14/849408 was filed with the patent office on 2015-12-31 for biodegradable cigarette filter tow and method of manufacture.
The applicant listed for this patent is Greenbutts LLC. Invention is credited to Vera Chetty, Tadas Lisauskas, Stephen Russell, Matthew Tipper, Xavier Alexander Van Osten.
Application Number | 20150374030 14/849408 |
Document ID | / |
Family ID | 54554479 |
Filed Date | 2015-12-31 |
United States Patent
Application |
20150374030 |
Kind Code |
A1 |
Lisauskas; Tadas ; et
al. |
December 31, 2015 |
BIODEGRADABLE CIGARETTE FILTER TOW AND METHOD OF MANUFACTURE
Abstract
A biodegradable cigarette filter tow includes a mixture of at
least two or more natural materials selected from the group
consisting of hemp fiber, flax fiber, abaca fiber or pulp, sisal
fiber or pulp, wood pulp, and cotton fiber or cotton flock. The
mixture may also include regenerated cellulose fibers. The mixture
may include a natural binder or may be hydroentangled.
Inventors: |
Lisauskas; Tadas; (San
Diego, CA) ; Van Osten; Xavier Alexander; (San Diego,
CA) ; Tipper; Matthew; (York, GB) ; Chetty;
Vera; (Mirfield, GB) ; Russell; Stephen;
(Harrogate, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Greenbutts LLC |
San Diego |
CA |
US |
|
|
Family ID: |
54554479 |
Appl. No.: |
14/849408 |
Filed: |
September 9, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/US2015/018355 |
Mar 2, 2015 |
|
|
|
14849408 |
|
|
|
|
62002608 |
May 23, 2014 |
|
|
|
Current U.S.
Class: |
131/345 ;
131/331; 162/146 |
Current CPC
Class: |
A24D 3/068 20130101;
A24D 3/14 20130101; A24D 3/08 20130101; D21H 13/08 20130101; A24D
3/0229 20130101; D21H 11/12 20130101; A24D 3/10 20130101; A24D 3/06
20130101 |
International
Class: |
A24D 3/06 20060101
A24D003/06; D21H 11/12 20060101 D21H011/12; A24D 3/08 20060101
A24D003/08; D21H 13/08 20060101 D21H013/08; A24D 3/02 20060101
A24D003/02; A24D 3/10 20060101 A24D003/10 |
Claims
1. A biodegradable cigarette filter tow, comprising: at least two
natural fibrous materials, the natural fibrous materials being
selected from the group consisting of: hemp, flax, abaca, sisal,
wood pulp, and cotton; and regenerated cellulose fiber.
2. The filter tow of claim 1, wherein the natural fibrous materials
include at least one of abaca, sisal and wood pulp.
3. The filter tow of claim 1, further comprising a natural
binder.
4. The filter tow of claim 1, comprising: 0-50% by weight of hemp
fiber or hemp filler; 0-50% by weight of flax fiber or flax filler;
0-95% by weight of abaca fiber or abaca pulp; 0-95% by weight of
sisal fibers or sisal pulp; 0-50% by weight of wood pulp; 0-50% by
weight of cotton fibers or cotton flock; 0-50% by weight of
regenerated cellulose fibers; and 0-30% by weight of a natural
binder.
5. The filter tow of claim 4, wherein the natural binder is
selected from the group consisting of natural latex, vegetable gum,
starch based binder, cationic starch binder, carboxymethyl
cellulose, and other biopolymer and bio based polymers.
6. The filter tow of claim 1, wherein the natural fibrous materials
comprise at least one of hemp and flax material, at least one of
abaca, sisal, and wood pulp material, and cotton fiber or cotton
flock.
7. The filter tow of claim 6, further comprising a natural binder
comprising a cationic starch.
8. The filter tow of claim 1, comprising: 1-50% by weight of hemp
or flax fiber or filler; 1-95% by weight of abaca or sisal pulp or
fiber or 1-50% by weight of wood pulp; 1-50% by weight of cotton
fiber or cotton flock; and 1-50% by weight of regenerated cellulose
fibers.
9. The filter tow of claim 8, comprising: 5-25% by weight of hemp
or flax fiber or filler; 20-50% by weight of abaca or sisal pulp or
fiber or wood pulp; 10-30% by weight of cotton flock; and 30-40% by
weight of regenerated cellulose fibers.
10. The filter tow of claim 9, comprising 5-25% by weight of
hemp.
11. The filter tow of claim 9, comprising no more than 20% by
weight hemp or flax filler.
12. The filter tow of claim 9, comprising 30 to 45% by weight
abaca, sisal or wood pulp.
13. The filter tow of claim 9, comprising 15 to 30% cotton
flock.
14. The filter tow of claim 8, further comprising a natural
binder.
15. The filter tow of claim 8, wherein the natural fibrous
materials include at least one or more of hemp and flax cut to a
mean fiber length of less than 3.5 mm and having a predetermined
fiber diameter.
16. The filter tow of claim 15, wherein the fiber diameter is no
greater than 500 .mu.m.
17. The filter tow of claim 8, wherein the cotton fiber length is
in the range of 250-1000 .mu.m and the cotton fiber thickness is in
the range from 10-50 .mu.m.
18. The filter tow of claim 1, wherein the regenerated cellulose
fibers have a fiber length in the range from 2 to 6 mm.
19. The filter tow of claim 1, wherein the fibrous materials are
formed into a fibrous web having an open bulky structure with a
volume density of no greater than 200 kgm.sup.-3 and the fibrous
web has an air permeability of greater than 100
cm.sup.3cm.sup.-2sec.sup.-1 at a differential pressure of 200
Pa.
20. The filter tow of claim 1, wherein the fibrous materials are
formed into a fibrous web having an areal density in the range from
25 gm.sup.-2 to 65 gm.sup.-2.
21. A biodegradable cigarette filter material comprising at least
two or more natural fibrous materials, at least one of the natural
fibrous materials being selected from the group consisting of wood
pulp, abaca and sisal and at least one other natural fibrous
material being selected from the group consisting of hemp, flax and
cotton.
22. The biodegradable cigarette filter material of claim 21,
comprising a non-woven fibrous web.
23. The biodegradable cigarette filter material of claim 21,
further comprising a regenerated cellulose fiber.
24. The biodegradable cigarette filter material of claim 21,
further comprising a natural binder.
25. The biodegradable cigarette filter material of claim 23,
comprising a mixture of hemp, cotton, regenerated cellulose fiber,
and one natural fibrous material selected from wood pulp, abaca and
sisal.
26. The biodegradable cigarette filter material of claim 23,
comprising a mixture of hemp, cotton, regenerated cellulose fiber,
and wood pulp.
27. A method of making a biodegradable cigarette filter material,
comprising: dispersing a mixture of fibrous materials in water, the
fibrous materials comprising at least two natural fibrous materials
selected from the group consisting of hemp, flax, abaca, sisal,
wood pulp and cotton in water; forming the dispersed fiber mixture
into a non-woven fibrous sheet in a wetlaid or papermaking machine;
removing excess water from the non-woven fibrous sheet using
suction; adding a natural binder to the fiber mixture prior to or
during formation of the non-woven fibrous sheet; drying the
non-woven fibrous sheet; and forming the non-woven fibrous sheet
into cigarette filter tow.
28. The method of claim 27, wherein the mixture of fibrous
materials comprises 0-50% by weight of hemp fiber or hemp filler;
0-50% by weight of flax fiber or flax filler; 0-95% by weight of
abaca fiber or abaca pulp; 0-95% by weight of sisal fibers or sisal
pulp; 0-50% by weight of wood pulp; 0-50% by weight of cotton
fibers or cotton flock; and 0-50% by weight of regenerated
cellulose fibers.
29. The method of claim 27, wherein the natural binder is selected
from the group consisting of natural latex, vegetable gums, starch
based binders, cationic starch binder and carboxymethyl cellulose
(CMC).
30. The method of claim 29, wherein the mixture of fibrous material
comprises 5-25% by weight of hemp or flax fiber or filler; 20-50%
by weight of abaca or sisal or wood pulp or fiber; 10-30% by weight
of cotton flock; and 30-40% by weight of regenerated cellulose
fibers.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The present invention relates generally to a biodegradable
cigarette filter and more specifically, to a non-synthetic, natural
cigarette filter tow.
[0003] 2. Related Art
[0004] Popular smoking articles have undergone significant
development in the past 50 years with a recent increased awareness
of limiting consumption of chemicals which can impede the emotional
enjoyment of smoking cigarettes or other products. In addressing
the desire for an enhanced smoking experience, much research and
development has centered around the cigarette filter which
currently primarily serves the purpose of filtering the smoke
generated from burning tobacco. Typically, a filter has a filter
tow made from plasticized cellulose acetate and can also include
polyhydric alcohols, and the tow is wrapped with an inner and outer
layer of cigarette paper. The inner layer is known as the plug wrap
and the outer wrapping layer is known as the tipping paper. A
cigarette is smoked by a consumer lighting one end and burning the
tobacco rod end of the cigarette, opposite from the filter. The
smoker then receives mainstream smoke into his mouth by drawing the
tobacco smoke through the filter on the opposite end of the
cigarette.
[0005] Certain cigarettes incorporate filter elements or tows
having absorbent materials dispersed therein, such as activated
carbon or charcoal materials in particulate or granular form. For
example, a cigarette filter can possess multiple segments, and at
least one of those segments can comprise particles of high
carbon-content materials.
[0006] In other areas of the art, cellulose acetate is known and
widely used in cigarette filter material. In most forms the
biodegradability of cellulose acetate remains relatively low.
Further, the biodegradation character of cellulose acetate is most
often dependent on the degree of substitution, or the number of
acetyl groups per glucose unit of the cellulose acetate molecular
structure. For example, if the degree of substitution of cellulose
acetate is decreased, the biodegradation rate of cellulose acetate
is increased.
[0007] A typical cigarette includes a filter at one end which has a
core or body which filters the smoke generated from burning tobacco
and a paper wrapper having one or more wrapper layers surrounding
the filter body. The filter core or body is commonly made from a
fibrous filter material and a binder. After a user smokes the
cigarette, the filter or cigarette butt is typically discarded.
Such filters are often discarded in outdoor areas such as beaches,
parks, and the like. The materials making up the filter core and
binder biodegrade only very slowly over lengthy periods of time and
thus cause unsightly environmental litter and pollution.
[0008] Attempts have been made to address the problem of
non-biodegradable materials in filter cigarettes. In some studies,
investigators have sought to introduce micro-organisms which act to
accelerate the degradation process. In such methods however, the
biodegradation rate of the entire filter is determined by the
biodegradation rate of the material that can be easily biodegraded
and, thus, the biodegradation rate of the cellulose acetate itself
is not increased.
[0009] Other proposals for biodegradable and partially
biodegradable filters involve relatively complicated manufacturing
processes which often require chemical intermediates for
production. Moreover, such methods also do not address the issue of
introduction of complex chemical compounds into the environment
which leads to pollution.
[0010] As such, there exists a need for a filter and methods for
producing a more environmentally friendly cigarette filter to
assist in decreasing pollution and litter from cigarette filters
which currently employ use of chemicals and materials that are
synthetic, non-biodegradable and harmful to smokers and the
environment.
SUMMARY
[0011] Embodiments described herein provide for an improved
biodegradable cigarette filter tow, an improved biodegradable
cigarette filter material, and an improved method of making a
biodegradable cigarette filter material.
[0012] According to one embodiment, a biodegradable cigarette
filter tow is made from a mixture of two or more natural fibers or
pulps or man-made fibers derived from natural sources, selected
from the group consisting of hemp fiber, flax fiber, wood fiber
pulp, abaca fiber or abaca pulp, sisal fiber or sisal pulp, and
cotton fiber or cotton flock. In one example, the filter mixture
also contains a man-made fiber derived from a natural resource such
as wood pulp, for example regenerated cellulose fiber such as
Tencel.RTM., viscose, or Lyocell.RTM.. In one embodiment, the
cigarette filter mixture contains three natural fibers or
pulps.
[0013] In one embodiment, the biodegradable cigarette filter tow
contains abaca or sisal pulp along with at least one other natural
fiber material. According to one aspect, the abaca or sisal is in
the form of pulp or short cut fiber. In one embodiment, the
biodegradable cigarette filter tow contains wood pulp in place of
abaca or sisal fiber or pulp, or in addition to abaca or sisal
fiber or pulp. In one aspect, the biodegradable cigarette filter
tow is made from a non woven, fibrous sheet of abaca or sisal pulp
or fiber, hemp or abaca filler, cotton flock, and regenerated
cellulose fiber, and may also contain a natural binder such as
cationic starch.
[0014] In one aspect, the biodegradable filter tow comprises:
[0015] 20-60% by weight of abaca or sisal pulp or fiber or wood
pulp, or 20-60% by weight of combinations of two or more of wood
pulp, abaca pulp or fiber, and sisal pulp or fiber; [0016] 5-25% by
weight of hemp or flax short cut fibers or filler; [0017] 10-35% by
weight of cotton flock; [0018] 5-40% by weight of regenerated
cellulose fiber.
[0019] In one embodiment, the mixture also includes a natural
binder or a binder manufactured from natural renewable sources. The
binder may be derived from biopolymers or bio-based polymers, such
as starch, a water soluble biodegradable polymer material such as
carboxymethyl cellulose. The binder is water soluble to create a
solution, or water dispersible to create binder dispersion/emulsion
in water. Binder solution/dispersion/emulsion viscosity is adjusted
to comply with the application process. Solid binder content
applied on the fibrous web varies in range 2%-30% of dry weight. In
another embodiment, no binder is used, and the filter is
manufactured using a wetlaid and hydroentanglement process.
[0020] In one embodiment, the natural binder is selected from the
group consisting of natural latex, vegetable gums, biopolymer or
bio-based binders, such as starch based binders, cationic starch
binder and binders made from renewable sources such as
Carboxymethyl cellulose (CMC).
[0021] In one embodiment, an intimate blend of two or more natural
fibers is used to form a nonwoven sheet for manufacturing of a
cigarette filter element. The fiber blend also contains fiber from
a regenerated natural polymer, preferably cellulose. A natural
binder (adhesive) or binder derived from a natural source is
applied to the nonwoven sheet. The binder may be applied such that
it coats all of the constituent fiber surfaces, or may be applied
in specific locations on the sheet. The optimum fiber morphology,
fiber composition, binder content and nonwoven sheet parameters
such as areal density, volume density, air permeability and
mechanical properties can be altered to obtain different
performance of a cigarette filter with respect to smoking
parameters, such as pressure drop and retention properties. These
depend on the particular product requirements. The binder provides
nonwoven material with the strength for converting process. The
water soluble binder allows for disintegration in dry state, and
promotes quick dispersibility in high moisture (humidity) and wet
state.
[0022] According to another aspect, a nonwoven sheet for use in
manufacture of a biodegradable cigarette filter comprises a mixture
of: [0023] 0-50% by weight of hemp fiber, hemp short cut fiber, or
hemp filler; [0024] 0-50% by weight of flax fiber, flax short cut
fiber, or flax filler; [0025] 0-95% by weight of abaca fiber or
abaca pulp; [0026] 0-95% by weight of sisal fibers or sisal pulp;
[0027] 0-50% by weight of wood pulp; [0028] 0-50% by weight of
cotton fibers or cotton flock; [0029] 0-50% by weight of
regenerated cellulose fibers; and [0030] 0-30% by weight of a
natural binder or a binder manufactured from natural renewable
sources.
[0031] According to another aspect, a method of making a
biodegradable cigarette filter comprises forming a suspension of
the selected natural fiber mixture in water and then draining water
from the mixture to form a fibrous, non-woven fiber sheet. The
non-woven sheet is then either coated/impregnated with a binder
solution, or hydroentangled using a hydroentanglement process, or a
combination thereof. Binder may be applied onto the fiber mixture
before or during nonwoven sheet formation. The sheets may then be
pressed between rollers, and cut into strips which are then formed
into cigarette filters.
[0032] Other features and advantages of the present invention will
become more readily apparent to those of ordinary skill in the art
after reviewing the following detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The details of the present invention, both as to its
structure and operation, may be gleaned in part by study of the
accompanying drawings, in which like reference numerals refer to
like parts, and in which:
[0034] FIG. 1 is a perspective cross-sectional view of a cigarette
incorporating a biodegradable filter element;
[0035] FIG. 1A is a cutaway view of part of the filter element of
FIG. 1;
[0036] FIG. 2 is a graph showing residual tensile strength of
samples comprising cotton fiber flock and wood pulp;
[0037] FIG. 3 is a graph showing residual tensile strength of
samples comprising hemp fiber filler and wood pulp;
[0038] FIG. 4 is a graph showing residual tensile strength of
samples comprising flax fiber filler and cotton fiber flock;
[0039] FIG. 5 is a graph showing residual tensile strength of
samples comprising flax fiber filler and wood pulp;
[0040] FIG. 6 is a graph showing residual tensile strength of
samples comprising flax short cut fibers and cotton fiber
flock;
[0041] FIG. 7 is a graph showing residual tensile strength of
samples comprising flax short cut fibers and wood pulp;
[0042] FIG. 8 is a graph showing air permeability of various
different sheet samples with applied binders;
[0043] FIG. 9 is a graph showing air permeability of another set of
sheet samples with different applied binders from FIG. 8;
[0044] FIG. 10 is a graph showing tensile strength of the same
samples as FIG. 9;
[0045] FIG. 11 is a graph showing tensile strength of samples
manufactured in a development phase 2 and pilot line trial; and
[0046] FIG. 12 is a graph showing air permeability of the same
samples as FIG. 11.
DETAILED DESCRIPTION
[0047] Certain embodiments as disclosed herein provide for a
biodegradable filter element made from 100% natural and compostable
materials, to be used in the manufacture of cigarettes containing
tobacco or other smokable materials or to be supplied to customers
for use in rolling their own cigarettes.
[0048] After reading this description it will become apparent to
one skilled in the art how to implement the invention in various
alternative embodiments and alternative applications. However,
although various embodiments of the present invention will be
described herein, it is understood that these embodiments are
presented by way of example only, and not limitation.
[0049] FIGS. 1 and 1A illustrate a cigarette 10 incorporating a
first embodiment of a biodegradable filter element or body 20
surrounded by one or more outer wrapper layers 18 at one end of the
cigarette. The remainder of the cigarette contains cigarette
tobacco 15 or other smokable material surrounded by an elongated
cylindrical tube 14 of cigarette paper. The filter material 16 of
filter body 20 includes a number of natural ingredients including a
biodegradable and compostable combination of natural fibers of
various types bound together with a natural binder solution or
dispersion, or hydroentangled. The surrounding paper or wrapper
layer is wrapped around the filter body and glued along a
longitudinal seam using any appropriate liquid starch adhesive.
[0050] An intimate blend of two or more natural fibers is used to
form a nonwoven sheet for manufacturing of cigarette filter element
20. The fiber blend also contains fibers from a regenerated natural
polymer, for example cellulose. A natural binder (adhesive) or
binder derived from a natural source is applied to the nonwoven
sheet. The binder may be applied such that it coats all of the
constituent fiber surfaces, or may be applied in specific locations
on the sheet. The optimum fiber morphology, fiber composition,
binder content and nonwoven sheet parameters such as areal density,
volume density, air permeability and mechanical properties can be
altered to obtain different performance of a cigarette filter with
respect to smoking parameters, such as pressure drop and retention
properties. These depend on the particular product
requirements.
[0051] The following describes examples of various different
combinations of natural fiber materials and binders as filter
elements and testing of the different embodiments of filter
elements for suitability in cigarette manufacture. The development
of the natural filter element is designed to conform to performance
standards suitable for the manufacture of standard cigarette
filters and roll-your-own filters.
[0052] The choice of fiber type is specifically targeted to satisfy
the requirements for biodegradability, compostability and
sustainability. The same applies to biodegradable binders applied
to the nonwoven materials, which are also derived from natural
sources, such as starch, biopolymers, natural rubber or gums, and
wood pulp.
1. Screening
[0053] Both constituent fiber materials and different nonwoven
fabric constructions (web formation and bonding) of some
embodiments of a biodegradable cigarette filter element or tow were
tested and compared, as summarized below.
1.1 Biodegradable Fibers
[0054] Biodegradable fibers, derived from natural sources, can be
divided into three main groups on the basis of the nature of raw
materials [0055] Plant fibers [0056] Protein fibers [0057]
Regenerated and modified man-made fibers from natural sources
[0058] Plant fibers are obtained from various parts of plants.
Fibers such as cotton (seed fibers), leaf and bast fibers and wood
pulp are commonly used in the manufacturing of nonwoven fabrics.
They can be subjected to carding, airlaying and wetlaying, and
consequently bonded by mechanical, chemical and thermal methods.
These fabrics may assist rapid biodegradation of the nonwovens
fabrics after product disposal, however, their variability in
morphology and structural quality strongly depend on climate and
weather conditions, protection against insect and fungi and
nutrition available in the soil. All these aspects can have
negative effect on fiber quality and consequently on products made
of these fibers. The most common commercially available plant
fibers are cotton fibers followed by bast fibers (flax, hemp, jute,
ramie, kenaf); leaf fibers (abaca, sisal) and wood pulp fibers used
mainly for making papers and wetlaid nonwovens.
[0059] Protein fibers are obtained from various animal species; the
most commonly commercially available animal hair fiber is sheep's
wool. Protein fibers, such as sheep's wool, are also commonly used
renewably sourced materials. Wool fibers can be subjected to
carding, airlaying as well as wetlaying, although only carding is
common commercially. Their affinity to liquid binders is relatively
low as well as their adhesion to thermoplastic binders, therefore
processing using chemical and thermal bonding methods for wool
fibers is very limited. The variability of morphology and quality
of wool fibers are also strongly dependent on the climate and
weather conditions, nutrition available to the animals. Wool fibers
also differ depending on the part of the sheep where they have
grown. Wool fibers from the sheep back are different from fibers
grown on the legs, for example. These factors have negative effect
on the homogeneity of the fibers. Due to the variability in fiber
quality, the production processes has to be regularly adjusted to
make sure that products of required parameters and properties are
obtained.
[0060] Man-made fibers, derived from natural renewable sources, are
generally produced from cellulose (wood) or starch (e.g. corn). The
most common and commercially available fibers from regenerated
cellulose are viscose and Tencel.RTM.. The cellulosic fibers offer
very good biodegradable performance. Fibers manufactured from
regenerated cellulose (e.g. viscose, Lyocell and Tencel.RTM.) are
highly uniform fibers identical to each other with respect to fiber
shape, diameter and length regardless of climatic weather
conditions and seasonal changes. Processing of these fibers into
nonwoven fabrics is commonplace employing a wide variety of web
forming and bonding processes. Products of consistent properties
are obtained without making significant adjustments during
processing.
[0061] The consistency in fiber morphology and properties is
critical for obtaining uniform nonwoven fabrics.
[0062] A list of some biodegradable fibers obtained from renewable
sources is provided below:
TABLE-US-00001 Fibers Form Web formation Cotton Staple fibers
Airlaid, Wetlaid, Carded Bast fibers (flax, Staple fibers, short
cut Airlaid, Wetlaid, Carded hemp, jute, ramie,
fibers/flock/filler, pulp kenaf) Leaf Fibers (abaca, Staple fibers,
short cut Airlaid, wetlaid, carded sisal) Fibers/flock/filler, pulp
Wood pulp Very short fibers Wetlaid, Airlaid Wool Staple fibers
Airlaid, Carded Silk Continuous filaments Viscose Staple fibers
Airlaid, Wetlaid, Carded Viscose rayon Spun-laid rayon Tencel
.RTM., Lyocell Staple fibers, short cut Airlaid, Wetlaid, Carded
fibers, filaments
[0063] Life cycle assessment (LCA) provides many criteria to
compare environmental impact of the individual fibers. Cotton
fibers, for example, are low energy intensive fibers and their land
use is relatively low. However the extensive water consumption and
usage of fertilizers and pesticides for cotton growth have
significant negative impact on the environment. On the other hand
man-made fibers from regenerated cellulose have high energy use but
perform well in all other criteria. Bast fibers, excluding the
bio-retted hemp fibers, use little energy and their water
consumption is also low. Their only disadvantage is higher land use
compare to other fibers and usage of fertilizers and pesticides in
the case of flax fibers.
[0064] In one embodiment, a blend of the following fibers is used
to form a nonwoven sheet for manufacturing of a cigarette filter
element: hemp or flax fibers or a combination of both hemp and flax
fiber; abaca or sisal fibers or a combination of both abaca and
sisal fibers; short cotton fibers or flock; wood pulp; and fibers
made from regenerated cellulose such as Tencel.RTM., Lyocell or
viscose. A natural binder or a binder manufactured from natural
renewable sources (typically wood pulp) is added to the nonwoven
material. Suitable binders are described in more detail below.
[0065] Hemp or flax fibers or a combination of both fiber types are
used to prepare the fiber blend. Very clean raw material with the
lowest possible content of hard shiv is preferred. Preferably, the
fibers are unbleached. Preferably, the fibers are cut or milled to
a short length of <3.5 mm. Fiber parameters for one embodiment
of the biodegradable cigarette filter are listed below: [0066] Raw
material cleanliness (hard wood/shiv content) is <95%,
preferably <97%, most preferably <99%; [0067] Mean fiber
length is <3.5 mm, preferably <1.5 mm, and most preferably
.ltoreq.1 mm; [0068] Fiber diameter is <500 .mu.m, preferably
<100 .mu.m and most preferably <50 .mu.m; [0069] Hemp or flax
fiber content in the nonwoven sheet ranges from 0-50% by
weight.
[0070] The hemp and flax fibers provide the filter material with
natural appearance, hardness, and their short length contributes to
the material's disintegration in dry state and dispersibility in
water. Due to the high surface area, the fibers also contribute to
the retention properties.
[0071] Abaca or sisal fibers or a combination of both are also used
to prepare the fiber blend. Both fibers have relatively high fiber
length and high strength. The fibers are unbleached. The fibers are
refined to ensure good dispersibility before the sheet formation.
Only limited level of refining is applied to open the fiber
structure slightly and allow only limited hydrogen bonding in the
nonwoven structure. The fiber length provides the material with
strength, and the low level of hydrogen bonding promotes the
disintegration in dry state and quick dispersibility in wet state.
A low brightness level is required to promote the natural look of
the product. Fiber parameters are listed below: [0072]
Wetness--fibers are supplied in low wetness (15-21SR) and slightly
refined to Wetness in range 20-30SR, preferably 21-25SR, most
preferably 21SR; [0073] Brightness--60-75%; [0074] Fiber content in
the nonwoven material is in range 0%-95% by weight.
[0075] Abaca or sisal pulp provides the filter material with high
dry tensile and tear strength, contribute to wet strength important
during nonwoven manufacturing. The low level of refining promotes
disintegration in dry state and quick dispersibility in wet state.
The relatively low level of refining enhances low volume density
and high air permeability of the material. The fibers also
contribute the natural appearance of the material. Pulp fiber
content in the structure also contributes to the mass uniformity of
the material.
[0076] Wood pulp fibers are also used to prepare the fiber blend in
some embodiments, either in addition to abaca or sisal fibers, or
as an alternative to abaca or sisal. Wood pulp fibers are selected
from grades designed to provide relatively long fibers and high
bulk to the sheets. No refining or only a limited level of refining
is applied to open the fiber structure slightly and allow only
limited hydrogen bonding in the nonwoven structure. The fiber
length provides the material with strength, and the low level of
hydrogen bonding promotes the disintegration in dry state and quick
dispersibility in wet state. A low brightness level is required to
promote the natural look of the product. Fiber parameters are
listed below:
[0077] Wetness--fibers are supplied in low wetness (14-20SR) and
slightly refined to Wetness in range 21-25SR, preferably 21SR, most
preferably below 20SR;
[0078] Brightness--<90%, preferably <85%, most preferably
<80%;
[0079] Fibre length-->1.5 mm, preferably >2 mm and most
preferably >2.5 mm;
[0080] Fibre width-->20 .mu.m, preferable >30 .mu.m, and most
preferably >40 .mu.m.
[0081] Wood pulp fibers enhance the tensile of filter material. The
low level of refining promotes disintegration in the dry state and
quick dispersibility in the wet state. The relatively low level of
refining enhances low volume density and high air permeability of
the material. Pulp fiber content in the structure also contributes
to the mass uniformity of the material.
[0082] Short cotton fibers/flock used in the fiber blend are
unbleached. The fibers are cut or milled from cotton linters (waste
from cotton fiber textile processing). The fiber parameters are
shown below:
[0083] Fiber length requires <5000 .mu.m, preferably <1500
.mu.m, ideally in range 250-1000 .mu.m;
[0084] Fiber thickness average 10-50 .mu.m, preferably 10-20
.mu.m;
[0085] Fiber content in the nonwoven material is in range
0-50%.
[0086] The short fiber length contributes to material
disintegration in dry state and quick dispersibility in wet state.
Fibers obtained from waste material contribute to the sustainable
claims of the product. The unbleached cotton fibers also contribute
to the natural appearance of the product.
[0087] Tencel, Lyocell or viscose fibers are man-made fibers
derived from natural resources (typically wood pulp). Fiber
parameters are shown below:
[0088] Fiber linear density in range 1.7-3.3 dtex;
[0089] Fiber length in range 2-6 mm;
[0090] Fiber content in the nonwoven material in range 0-50%.
[0091] The fiber length is selected to ensure good dispersiblity in
fiber dispersion before the web formation process, and also provide
the material with great wet strength during processing. Fibers from
regenerated cellulose contribute to the materials tensile strength
and enhance mass uniformity.
1.2 Biodegradable Binders
[0092] Binders are used in nonwoven production to enhance tensile
strength of fibrous structures by forming adhesive bonds between
the fibers. Many chemical bonding binders are man-made from
non-renewable sources; materials such as Styrene Butadiene Rubber
(SBR), acrylics and vinyl acetate polymers are commonly employed.
These materials are generally cross-linking emulsion polymers
activated by heat but are not considered biodegradable.
[0093] Biodegradable binders are usually dissolved into a solution
or dispersed into a dispersion/emulsion and applied on fibrous
structure in liquid form. Hence the structure is dried and the
binder consolidated in the structure providing improved mechanical
properties.
[0094] In one embodiment, a natural binder or binder manufactured
from natural renewable sources is used. The binder is water soluble
to create a solution, or water dispersible to create binder
dispersion/emulsion in water. Binder solution/dispersion/emulsion
viscosity is adjusted to comply with the application process. Solid
binder content applied on the fibrous web varies in range 2%-30% of
dry weight.
[0095] The natural binder can be natural latex, vegetable gums,
biopolymer based (also bio based polymers) such as starch based
binders, cationic starch binder and binders made from renewable
sources such as carboxymethyl cellulose (CMC).
[0096] The binder provides nonwoven material with the strength for
converting process. The water soluble binder allows for
disintegration in dry state, and promotes quick dispersibility in
high moisture (humidity) and wet state.
[0097] Carboxymethyl cellulose (CMC) is a water-soluble
biodegradable polymer made from renewable sources (wood pulp) and
used in nonwoven fabrics as a binder.
[0098] Starches are also polysacharide-based polymers extracted
from variety of plants (maize, wheat, potato, rice, tapioca). They
are water soluble and biodegradable and are widely used in
papermaking industry.
[0099] Natural rubber (Polyisoprene) is commonly used binder in
nonwoven fabrics. It is derived from latex, a milky colloid
produced by some plants. It is biodegradable and commercially
available in the form of water-based emulsions. Sodium alginate
binder, a salt of alginic acid extracted from seaweed has also been
employed in nonwoven applications.
1.3 Manufacturing of Nonwoven Fabrics
[0100] Nonwoven fabrics are flat, porous sheets made directly from
separate fibers or from molten polymers formed into filaments. By
forming webs of fibers or filaments and consequently bonding them
by mechanical (inter-fiber friction), thermal or chemical means,
strong, lightweight fabrics are produced.
[0101] Drylaid and wetlaid web formation processes use staple
fibers to form fibrous webs, including plant fibers, protein fibers
and man-made fibers. Spunbond and meltblowing processes are
suitable for thermoplastic polymers and special types of fibers
from renewable sources. All types of fibrous webs can be bonded by
using any of the web bonding methods, however certain combinations
of web formation and web bonding are more common in manufacturing
of nonwoven fabrics than others.
1.3.1 Wetlaid Web Formation
[0102] Wetlaid paper and wetlaid nonwovens are fibrous webs with
highly uniform structure made by a paper making process or a
modified papermaking process, respectively. Disintegrated fibers
are suspended and dispersed in water to make a slurry. The slurry
is then transported to a formation wire where fibers form a uniform
sheet of material while water is drained off the fibers. Fibers
used in wet laid process are usually shorter than 10 mm.
1.3.2 Drylaid Web Formation
[0103] In the drylaid process, fibrous webs are prepared from
staple fibers usually 12 to 200 mm long using the carding process
or airlaying to separate and orientate the fibers. Carding is the
most common process to produce fibrous webs with predominately
parallel fiber orientation in the machine direction (production
direction). Parallel-laid structures are created by layering
several carded webs. More randomized structures are obtained by
cross-lapping of the carded web at an angle.
[0104] Structures with more isotropic fiber orientation are formed
using the airlaid process. The process involves disentanglement of
staple fibers, their dispersion in a strong stream of flowing air
and deposition on a forming wire. Again, fibers commonly used in
airlaid processes are usually shorter than 10 mm.
1.3.3 Mechanical Web Bonding for Nonwovens
[0105] Two main processes are used for mechanical bonding of
nonwoven structures where the strength of the fabrics is secured by
friction between fibers enhanced by intensive fiber entanglement.
In the needle punching process, the fibers are mechanically
interlocked throughout the fibrous web by the action of barbed
needles moving perpendicularly to the plane of the web,
transporting fibers captured in the grooves of needle barbs.
Hydroentanglement (also known as spunlacing, hydraulic
entanglement, or water jet needling) uses high-pressure water jets
running through a fibrous web perpendicularly to its plane to
initiate the fiber migration through the web and intensive
entanglement.
[0106] The interaction of the energized water with fibers in a web
and support surface increases the fiber entanglement and induces
displacement and rearrangement of fiber segments in the web to
achieve mechanical bonding. Hydroentanglement is a binder free
process.
1.3.4 Chemical Web Bonding
[0107] Bonding a web by means of application of a polymer solution,
emulsion or dispersion is one of the most common methods for
bonding of nonwoven fabrics. Several methods are used to apply a
binder in liquid or foam form to the web, such as padding, coating,
dipping, spraying, print bonding and foam bonding. Subsequently,
the web with applied binder is dried and thermally cured to obtain
bonding action and consolidation. In the case of wetlaid nonwovens
and paper manufacturing, the binder solution/emulsion/dispersion
can also be added into the fiber mix prior to sheet formation. The
fibrous web with binder is dried and thermally cured to obtain
bonding action and consolation.
1.3.5 Thermal Web Bonding
[0108] Thermal bonding processes use heat to bond and stabilize
fibrous webs that comprise of a thermoplastic binder. The binder
can be in the form of thermoplastic fibers integrated into the
structuring fiber formation or a powder, perforated foil,
thermoplastic net or web, etc. There are three methods for thermal
bonding. Calendaring uses hot rollers to apply direct heat and
pressure to achieve bonding within the fibrous structures.
Circulating hot air through a fibrous web is used for bonding in a
hot-air oven. A heat radiation source can be also used as a
non-contact thermal bonding process. The disadvantage of thermal
bonding is the traditional used of non-biodegradable thermoplastic
binders.
1.4 Screening Conclusions
[0109] Considering all the aspects related to different types of
biodegradable fibers from renewable sources, suitable candidates
for formation of nonwoven fabrics are selected from the group of
plant fibers (hemp, cotton, flax, abaca, sisal) and fibers made
from regenerated cellulose (viscose, Lyocell and Tencel.RTM.). The
fabrics can be subjected to carding, airlaying or wetlaying
formation processes. Mechanical or chemical bonding can be applied
to consolidate and stabilize the fibrous webs and enhance their
mechanical properties of the nonwoven structures. Mechanical
bonding is a binder free method. Chemical bonding methods can be
used to apply water-soluble biodegradable binders on the fibrous
webs. Thermal bonding uses thermoplastic polymer, which are
generally non-biodegradable and therefore it is not suitable for
nonwovens with required rapid degradation.
Example Manufacturing Process
[0110] In one embodiment, a fibrous web (wetlaid nonwoven or
wetlaid paper) of the fiber composition described above is formed
by a wetlaid or paper making process. The process involves
dispersion of fibers in water, delivery of the fiber dispersion to
the formation wire of a wetlaid or papermaking machine (flat wire,
incline wire, cylindrical mold machine, etc.). The technical
differences between the processes are well known and described in
literature. The concept is based on the fibers in the form of
dispersion in water being deposited on the formation wire (aperture
belt) and subsequent removal of excess water from the fiber layer
by a suction system. The selection of the machinery, setting of
process parameters, and addition of process additives depend on the
type and morphology of fibers involved in the process. The process
parameters are set to provide sufficient fiber dispersion, uniform
deposition of fibers on the forming wire, fiber orientation in the
fibrous web and areal density of the product.
[0111] A binder is applied to the formed web for web bonding. In
one embodiment, the binder is in a form of solution/emulsion or
foamed solution/emulsion. The binder solution/emulsion is selected
to have parameters (viscosity, solid content, pH value, ionic
concentration, and the like) to comply with the application process
and deliver the required solid binder content on the web. Any
chemical bonding process can be used, which includes but is not
limited to: coating or scraper bonding, impregnation/saturation,
printing, spray and/or foam bonding, etc. The processes are well
known and described in literature. The binder solution/emulsion can
also be added to the dilute fiber suspension prior the web
formation process on the machine wire. The binder particles are
mixed with the fibers in water dispersion, and deposited onto the
forming wire with the fibers.
[0112] By choice of binder type and binder content, the
characteristics of the fibrous web can be varied from soft and
drapeable to stiff, rigid or rubbery.
[0113] The properties of binder systems can be enhanced or cost
reduced by addition of other materials. This is important in
facilitating of the bonding processing, enhancing the bonded web
parameters and also for cost reduction. The auxiliaries include
fillers, thickeners, antifoaming agents, dispersing agents, and
other. Their functions are well known and described in
literature.
[0114] Conventional drying processes are used to evaporate excess
water and enhance the bonding of fibrous web. Convection or
conduction dryers with horizontal, vertical or cylindrical drying
drums are used. The type of a dryer and drying parameters
(temperature, heat and mass transfer, production speed) are set to
enhance the product parameters, such as mechanical properties in
dry and wet state, the disintegration and dispersion of the final
product in dry, moist or wet conditions.
[0115] In one embodiment, a fibrous web with applied cationic
starch binder is dried in a conventional hot air oven. The drying
conditions are set to dry the material but prevent excessive
shrinking and degradation of the binder. The drying temperature
should be set <200.degree. C., preferably <160.degree. C.,
ideally <110.degree..
2. Development of Natural Biodegradable Cigarette Filter
Material
[0116] The development stage involved formation of nonwoven sheets
from the acquired fibers and binders, and evaluation of their
parameters and properties. A sheet-forming machine was used to
manufacture small-scale nonwoven sheets from the different blends
of natural fibers and wood pulp. Biodegradable binders were applied
on the sheets using pad mangling. To identify the most suitable
materials, the properties of the fabrics, including tensile
strength, biodegradability and air permeability have been
determined according to standard test methods.
[0117] This involved sourcing suitable types of fibers and binders,
and prototyping of modified fabrics. The wetlaid process was
identified as the most appropriate method to form nonwoven sheets
for the cigarette filter application.
[0118] The fibers acquired are commercially available natural plant
fibers such as hemp, flax and cotton. Wood pulp is a material
obtained from natural source, particularly from Scandinavian soft
wood trees. Biodegradable binders applied to the nonwoven sheets
are derived from natural sources.
2.1 Selection of Appropriate Fibers and Binders
[0119] The fibers and binders selected for the cigarette filter
element have to meet the requirements of biodegradability,
compostability and sustainability. Hemp fibers are extracted from
stems of Cannabis saliva plants. Cotton fibers are extracted from
capsules protecting cotton seeds. Sisal fibers are extracted from
the leaves of Agave sisilana plant and abaca from leaves of Musa
plants. All fibers are therefore considered as materials obtained
from sustainable sources.
[0120] The list of acquired natural fibers and their parameters are
shown below. The wood pulp was in a form of water suspension, and
the wood pulp content in the suspension was 2%. Suppliers used as
sources for the fibers used in testing the filter material are
provided by way of example only, and similar fibers may be obtained
from other sources.
TABLE-US-00002 Cut Fiber length coarseness Supplier Fiber type Type
[mm] [.mu.m] Colour Procotex Flax fiber filler quality A 4 Not
specified natural Flax short cut F513/6 6 10-500 natural STW Hemp
fiber F517/800 .apprxeq.3 10-50 natural filler Goonvean Cotton
fiber CD5000 .ltoreq.5 10-20 natural Fibers flock Sodra Sodra black
kraft soft wood pulp
[0121] Some suitable binders obtained from natural and sustainable
sources for use in the cigarette filter element are starch based
binders, biopolymer based binders, and isoprene or natural rubber
binders. Suppliers used as sources for the binders used in testing
the filter material are provided by way of example only, and
similar binders may be obtained from other suppliers.
TABLE-US-00003 Concentration of Supplier Binder Type Polymer
solution (%) National RediBOND .RTM. 4000 Starch based 32 Starch
OrganoClick OC-biobinder Biopolymer based 20.4 Synthomer Revultex
Isoprene (Natural 61 rubber)
[0122] One example of a suitable binder is a liquid, ready-to-use,
cationic starch extracted from plant sources, such as maize, wheat,
potato, rice or tapioca, such as RediBOND.RTM. available from
Ingredion UK Limited of Manchester, UK. The material has been
developed to improve dry tensile strength, softness and absorbency
of the textile or paper materials.
[0123] Another example of a suitable binder is biopolymer based,
such as OC-biobinder available from OrganoClick of Taby, Sweden.
The type of polymer in OC-biobinder has not been revealed by the
supplier. It is suggested that it is composed from completely
renewable substances, such as modified biopolymers, water and
natural plant compounds. It is used for improving mechanical
properties of nonwoven textiles. It is considered nontoxic for
humans and biodegradable.
[0124] Another binder which was tested is based on natural latex or
rubber, such as Revultex, which is water-based dispersion of
natural latex (rubber) with additives, manufactured by Synthomer of
Harlow, UK. Natural latex is a milky colloid produced by some
plants, such as the para rubber tree. Natural latex is insoluble in
water, however colloidal particles can be dispersed in water and
this water-based dispersion is widely used as adhesive in paper and
carpet industries. Natural latex does not contain any critical
hazards to man and environment, however it contains natural rubber,
which can cause allergic reactions for some people.
2.2 Prototype Filter Material Formation
[0125] Small-scale prototype nonwoven sheets were formed in a sheet
forming machine in accordance with TAPPI T205 standard of the
forming machine.
[0126] Fiber blends were dispersed in water to create a fiber
suspension. A volume of the suspension for formation of one sheet
was measured out in a beaker. The sheet former was filled with
water and the fiber suspension added. The water-fiber suspension
was then stirred using a perforated stirrer. After 5.+-.1 seconds,
the machine drain was fully opened and the water drained through
the wire grid plate under suction. The fibers were collected on the
forming wire in the form of a fibrous sheet. The machine was opened
and two pieces of standard blotting paper were placed on top of the
fiber. The web and blotting paper were then removed, stacked
between polished plates and pressure was applied in a press
(stacked with 9 other samples). A pressure of 50 psi was applied
for 5 minutes. After the pressure was released, the sheets were
adhered to the polished plates so that the blotters were peeled off
and discarded. The individual samples were fitted into drying rings
and fully dried before peeling off the plate.
2.3 Binder Application
[0127] A padding machine was used to apply a binder solution on the
nonwoven sheets. The liquid binders were diluted to 10% wt.
solutions. All sheets were placed in a polyamide net prior
processing to prevent displacement and elongation during the
padding process, which would not be required on a production-scale
process. Clean moving padding rolls were pressed together at 1 kg.
cm.sup.-2; the rotational speed was 2 rpm. 40 ml of the binder
solution was poured and held between the rolls. The net and sheet
were immersed in the binder solution, captured between the padding
rolls and pulled through. The impregnated sheets were dried to
constant weight at 102.degree. C.
2.4 Test Methods
2.4.1 Tensile Strength
[0128] An Instron Tensile Tester, with a constant rate extension,
was used to evaluate the tensile strength of the nonwoven sheets.
The width of the tested specimen was 25 mm, the gauge length 75 mm
and the loading speed 100 mm-min.sup.-1. Tensile strength is
defined as the force measured at the breaking point of a specimen
per the specimen width [N/25 mm].
2.4.2 Areal Density and Solid Binder Content
[0129] A digital analytical scale was introduced to evaluate the
areal density and solid binder content of the wetlaid sheets.
[0130] Areal density [g-m.sup.-2] is calculated from the weight m
[g] of an individual sheet and its area s [m.sup.2]:
Areal Density=m/s
[0131] The solid binder content [%] is calculated from a dry weight
of a sheet before binder application m.sub.1 [g] and after binder
application m.sub.2 [g]:
Solid Binder Content = 100 .times. ( m 2 - m 1 ) m 2
##EQU00001##
2.4.3 Biodegradability
[0132] A biodegradability test was carried out according to AATCC
Test Method 30-2004. The aim was to identify the time period for
biodegradation of the nonwoven sheets with applied binders. A
material is considered biodegraded if its residual tensile strength
is 10% or lower. The residual tensile [%] strength was calculated
as a ratio of the tensile strength measured after the
biodegradability test F.sub.2 [N/25 mm] to the original tensile
strength F.sub.1 [N/25 mm]:
Residual tensile strength = F 2 F 1 / 100 . ##EQU00002##
2.4.4 Air Permeability
[0133] The air permeability was tested according to BS EB ISO
9073-15:2008 standard using a Shirley Air Permeability Tester. A
tested specimen was placed on a test head of the air permeability
testing apparatus and sealed with a ring with adequate tension to
prevent distortion or side leakage while the test was being
performed. The air suction device was turned on, airflow regulated
until the maximum pressure drop .DELTA.p [Pa] value for each sheet.
Readings of the airflow Q [cm.sup.3/sec] were taken. The air
permeability K measured over an area 5 cm.sup.2 was calculated
according to formula:
K(5 cm.sup.2)=Q/.DELTA.p(cm.sup.3sec.sup.-15 cm.sup.-2)
Air permeability was also tested using EDANA standard WSP 70.01 at
pressure drop 200 Pa over the area of 20 cm.sup.2 or 5 cm.sup.2 and
presented in cm.sup.3sec.sup.-1cm.sup.-2.
2.4.5 Scanning Electron Microscope
[0134] The structure of selected sheets was observed using Scanning
Electron microscopy (SEM).
2.5 Results
2.5.1 Areal Density and Solid Binder Content
[0135] When manufacturing nonwoven sheets, the aim was to minimize
the wood pulp content in sheets comprised from textile fibers, such
as cotton, hemp and flax, in order to obtain a porous and flexible
structure. High wood pulp content is associated with more compact
sheets and dense structures similar to paper, which is not
favorable for cigarette filter applications. Conversely, some wood
pulp content is necessary to provide the sheets with sufficient
hydrogen bonding and the requisite tensile strength for further
handling and processing. Sheets with different fiber/wood pulp
contents were manufactured and tested. The wood pulp content for
sheets comprising cotton fiber flock was 10% wt. and for sheets
containing hemp fiber filler, flax fiber filler and flax short cut
fibers, 25% wt.
[0136] The same applies when flax/cotton and hemp/cotton blends
were prepared. The cotton fibers provide the sheet structure with
sufficient hydrogen bonding. It was determined, that a minimum
content of 50% wt. cotton fiber flock was needed to obtain sheets
with sufficient strength for handling and processing.
[0137] The sheet forming process described in Section 2.2 involves
a number of operations, which influence the quality of the final
sheets. Sheets constructed from textile fibers reduces the hydrogen
bonding making handling of sheets difficult and can result in some
fiber loss to other surfaces. It has a negative effect on weight
variation in the individual sheets and hence the wide range of
areal densities of the individual sheets, as shown in Table 1
below. This does not occur while processing on a wetlaid pilot or
industrial line.
TABLE-US-00004 TABLE 1 Areal Solid Binder Notification Fiber
composition Binder applied Density(g/m.sup.2) Content (%) 1A 90%
cotton flock RediBOND (10%) 55-66 27-29 10% wood pulp 1B 90% cotton
flock OC-biobinder (10%) 57-60 23-24 10% wood pulp 1C 90% cotton
flock Natural Latex (10%) 56-58 18-23 10% wood pulp 2A 50% hemp
filler RediBOND (10%) 50-73 19-23 50% cotton flock 2B 50% hemp
filler OC-biobinder (10%) 58-67 19-24 50% cotton flock 2C 50% hemp
filler Natural Latex (10%) 54-70 15-22 50% cotton flock 4A 75% hemp
filler RediBOND (10%) 48-51 17-22 25% cotton 4B 75% hemp filler
OC-biobinder (10%) 48-64 14-16 25% cotton 4C 75% hemp filler
Natural Latex (10%) 47-56 14-15 25% cotton 5S - A 50% flax filler
RediBOND (10%) 56-70 26-28 50% cotton flock 5S- B 50% flax filler
OC-biobinder (10%) 49-67 23-24 50% cotton flock 5S -C 50% flax
filler Natural Latex (10%) 53-59 21-23 50% cotton flock 7S - A 75%
flax filler RediBOND (10%) 63-65 22-24 25% wood pulp 7S - B 75%
flax filler OC-biobinder (10%) 55-62 16-19 25% wood pulp 7S - C 75%
flax filler Natural Latex (10%) 56-58 20-31 25% wood pulp 5L -A 50%
flax short cut RediBOND (10%) 55-60 20-23 50% cotton flock 5L-B 50%
flax short cut OC-biobinder (10%) 55-60 21-23 50% cotton flock 5L-C
50% flax short cut Natural Latex (10%) 44-53 23-26 50% cotton flock
7L- A 75% flax short cut RediBOND (10%) 55-64 22-23 25% wood pulp
7L -B 75% flax short cut OC-biobinder (10%) 51-62 16-18 25% wood
pulp 7L- C 75% flax short cut Natural Latex (10%) 61-91 31-47 25%
wood pulp
2.5.2 Tensile Strength
[0138] The tensile strength of some embodiments of biodegradable
cigarette filter materials listed in Table 1 was also evaluated to
identify their ability to withstand the cigarette filter formation
process. 25 mm wide strips were cut from individual sheets and
clamped into an Instron Tensile Tester. The force was applied until
the breaking point was reached. The values of the tensile strength
and elongation at the breaking point have been recorded. The
results are shown in Table 2 below.
TABLE-US-00005 TABLE 2 Aeral Density Solid Binder Tensile
Elongation Sheet [g/m.sup.2] Binder Content [%] Strength [N] [mm] 1
55.5 A 28.0 37.0 2.7 60.2 B 22.7 50.4 3.4 56.7 C 17.9 7.6 6.1 2
59.6 A 23.4 19.5 2.9 58.0 B 23.8 36.4 2.9 54.7 C 14.8 2.3 4.7 4
49.8 A 2.3 16.5 2.2 48.1 B 15.8 16.7 1.4 55.5 C 14.5 8.0 2.8 5S
55.9 A 27.7 33.3 3.1 59.4 B 23.6 46.1 2.9 53.4 C 23.4 6.7 5.2 7S
63.6 A 22.1 69.4 3.9 60.5 B 18.0 73.4 2.7 68.3 C 30.0 14.2 4.2 5L
54.8 A 21.7 52.3 2.5 56.7 B 21.2 39.8 2.3 44.0 C 25.7 5.9 5.6 7L
55.0 A 23.4 66.8 2.9 57.6 B 17.1 87.4 2.5 61.5 C 31.7 18.4 4.2
[0139] It can be concluded that the OC-biobinder provides the
strongest bonding of the sheet structures. The values of tensile
strength of sheets with comparable areal density and solid binder
content are higher for sheets with applied OC-biobinder than
RediBOND.RTM.. The lowest tensile strength is achieved by sheets
with applied natural latex.
[0140] The results also show that the sheet comprising flax fiber
filler (5S and 7S) and sheets comprising short cut flax fibers (5L
and 7L) have higher strength than fibers comprising hemp fiber
filler (2 and 4). The highest strength is achieved by sheets
comprising flax fiber filler/wood pulp blend and flax short cut
fiber/wood pulp blends.
2.5.3 Biodegradability
[0141] The biodegradability of some embodiments of the nonwoven
sheets was assessed by the loss of tensile strength after a period
of time when the sheets were exposed to the conditions (moisture,
temperature) and fungal activity in the soil bed. The fungal
activity of the soil bed was evaluated using a pure cotton fabric
of 167 g-m.sup.-2. The fabric strips were inserted in the soil bed
and their tensile strength was evaluated every few days. The
material lost more 95% of its tensile strength after being buried
in the soil bed for 9 days. According to the standard, the fungal
activity is sufficient if the residual tensile strength of the pure
cotton fabric is 10% or lower after being in soil for 7 days.
Therefore the fungal activity in the soil bed inside the heated
propagators was considered sufficient.
[0142] A thin layer of soil was spread inside a heated propagator.
Four strips from each fiber/binder combination of width 25 mm and
length 125 mm were placed on the soil bed and covered with 2-3 cm
layer of soil. The soil moisture was monitored two times per day
using a soil moisture meter.
[0143] The conditions inside the heated propagator have also been
monitored during the test. The soil moisture was maintained at
20-25%, the air humidity was in the range of 90-98% rh and the
temperature inside the propagator in range 15-25.degree. C. The
tensile strength of the degraded strips was tested after being in
the soil bed for three, five and nine days. The test results for
the various compositions are shown in FIGS. 2 to 7.
[0144] All sheets with applied starch based binder A and bio-binder
B lost more than 90% of their tensile strength after being in the
soil bed for three days and therefore were considered
biodegraded.
[0145] The sheets comprising hemp fiber filler/wood pulp and flax
fiber filler/wood pulp blends with applied natural latex binder C
were also biodegraded after being in the soil bed for three days.
The sheets comprising flax fiber filler/cotton flock, flax short
cut fibers/cotton flock and flax short cut fibers/wood pulp with
applied natural latex binder were bio-degraded after being in the
soil bed for five days. The sheets comprising cotton flock/wood
pulp and hemp fiber filler/cotton flock and the natural latex
showed the highest resistance to the conditions in the soil bed and
were considered to be biodegraded after being in soil bed for nine
days.
2.5.4 Air Permeability
[0146] The air permeability results show that the sheets comprising
25% of wood pulp (4, 7S, 7L) allow lower volume of air to be passed
through their structure compared to sheets comprising 50% of cotton
fiber flock in the structure (2, 5S, 5L) and sheet comprising 90%
cotton flock and only 10% of wood pulp fibers (1), as shown in FIG.
8. The results indicate that the materials comprising 25% wood pulp
have lower porosity and therefore higher resistance to passing air.
With regard to different binders applied on the sheets, the sheets
with applied binder A have higher air permeability than the sheets
of the same fiber composition with applied binders B and C. The
sheets with applied binder A (5S-A and 5L-A) exhibit higher
porosity than the sheets with applied binders B and C (5S-B, 5S-C,
5L-B, 5L-C) and hence they allow higher air volume to pass through
their structure at the constant pressure drop.
2.5.5 Development Conclusions
[0147] The liquid binders of 10% concentration were applied on the
sheets. The solid binder content on the sheets was in range 22-28%
for binder A (RediBOND.RTM.), 16-24% for binder B (OC biobinder),
and 14-32% for binder C (Natural latex). The relatively narrow
range of the solid binder content for binder A proves that the
binder is evenly distributed and dispersed in the liquid solution.
Conversely, binder C (Natural latex) showed variable solid binder
content on the nonwovens. The colloidal particles of natural latex
are dispersed in water, not dissolved. If the dispersion is
unstable, a coagulation of the colloidal particles may occur which
has a negative effect on the uniformity of the particle
distribution in the dispersion, and subsequently an uneven binder
pick-up on the sheets is obtained. The coagulation of the colloidal
particles could be eliminated by using appropriate surfactant
additives.
[0148] Nonwovens sheets were formed in the range of area weight
47-67 gm.sup.-2. The range is considered quite high, however sheets
with similar area density were selected for the tensile and air
permeability testing and therefore the results are comparable. The
weight can be reduced during scale-up trials on full-scale or
prototype wetlaying lines.
[0149] The results of tensile strength show that the OC-biobinder
(binder B) provided the sheets with the highest tensile strength
values despite its lower solid binder content on the sheets
(16-24%) compared to the lower tensile strength values obtained for
sheets with applied binder A (RediBOND.RTM.) at higher solid binder
content (22-28%). As the aim is to have as little binder content on
the sheets as possible to retain the porous structure of the
nonwoven sheets, the OC-binder is the better binder to achieve this
aim. The lowest tensile strength was observed in the sheets with
natural latex binder at the solid binder content comparable or
higher than in the case of the OC-biobinder.
[0150] The highest values of tensile strength were obtained by
sheets comprising flax fiber filler/wood pulp and flax short cut
fibers/wood pulp blends, followed by cotton flock/wood pulp, flax
fiber filler/cotton flock and flax short cut fiber/cotton flock
blends. The sheets comprising hemp fiber filler showed the lowest
tensile strength. The hemp fibers filler is shorter than flax fiber
filler, flax short cut fibers and cotton fiber flock. The hemp
fiber filler also contains pieces of hard shiv, which are residues
of the core of the hemp plant not removed during the hemp fiber
manufacturing process. Both factors (short fiber length and
presence of the shiv) have a negative effect on the tensile
strength. Hemp fiber filler was obtained from three different
suppliers and the quality of the materials was very similar. It has
been confirmed that this is the standard quality of hemp fiber
filler commercially available.
[0151] The air permeability was higher for sheets comprised from
cotton fiber flock/wood pulp, hemp fiber filler/cotton fiber flock,
flax fiber filler/cotton fiber flock and flax short cut
fibers/cotton fiber flock compared to sheet comprising 25% wood
pulp fibers and hemp fiber filler, flax fiber filler and flax short
cut fibers, respectively. The application of RediBOND.RTM. (binder
A) resulted in the lowest reduction in air permeability.
[0152] The nonwoven sheets with starch based binder (such as
RebiBOND.RTM.) and biopolymer-based binder (such as OC-Biobinder)
exhibited excellent biodegradability. Most of the sheets with these
two binders applied were biodegraded after being exposed in the
soil bed for three days. All materials were bio-degraded after
being in the soil bed for five days. The nonwoven sheets with
applied natural latex were more resistant to biodegradation,
however all sheets biodegraded within five to nine days, which is
also considered a very good result.
[0153] The compositions of the nonwoven sheets manufactured in the
first phase of the development stage are listed in Table 3
below.
TABLE-US-00006 TABLE 3 Solid Areal binder density content Sheet
Fibre composition Binder applied [g/m.sup.2] [%] 5S 50% flax filler
A - RediBOND (10%) 63-65 22-24 50% cotton B- OC-biobinder (10%)
55-62 16-19 flock CD 5000 5L 50% flax short A - RediBOND (10%)
55-60 20-23 cut 50% cotton B- OC-biobinder (10%) 55-60 21-23 flock
CD 5000
[0154] The best performing binder was the OC-biobinder with regard
to improvement of the tensile strength of the sheets and
RediBOND.RTM. with regard to the lowest air permeability reduction.
The air permeability of the sheets is an important performance
parameter while the tensile strength is significant for the
processing of the nonwoven material into cigarette filters. If the
filtration performance is considered a priority then RediBOND.RTM.
or a similar starch based binder is a more suitable binder to be
applied on the nonwoven materials. It may be possible to modify
both properties by altering the concentration of the binder
solution, so both binders should not be discounted at this
stage.
3. Development--Phase 2
[0155] Sheets with fiber composition 50% flax filler/50% cotton
flock and 50% flax short cut fibers/50% cotton flock were selected
to be taken forward for further development. In one embodiment,
hemp filler was incorporated into flax/cotton nonwoven sheets at an
amount which will not affect the performance parameters.
3.1 Selection of Fibers and Binders
[0156] A better quality of hemp filler having a shorter fiber
length and containing smaller pieces of shiv was used in some
embodiments. A better quality of cotton flock with no yarn and
fabric residues was also acquired. The materials are listed below.
These materials help to improve the uniformity of the nonwoven
sheets.
[0157] The fiber parameters are given below.
TABLE-US-00007 Cut Fiber length coarseness Supplier Fiber type Type
[mm] [.mu.m] Colour Procotex Flax fiber quality A 4 Not specified
natural filler STW Flax short cut F513/6 6 10-500 natural Hemp
fiber F517/250 .apprxeq.1.5 10-50 natural filler Goonvean Cotton
fiber ECD24 <0.750 10-20 natural Fibers flock
[0158] In one embodiment, four types of nonwoven sheets were
manufactured. Their fiber compositions were: [0159] 1. 20% hemp
filler/30% flax filler/50% cotton flock [0160] 2. 20% hemp
filler/30% flax shot cut fibers/50% cotton flock [0161] 3. 50% flax
filler/50% cotton flock [0162] 4. 50% flax short cut fibers/50%
cotton flock
[0163] Three types of binders from natural and sustainable sources
were applied on the nonwoven sheets. Very low values of tensile
strength were obtained for sheets with applied natural rubber
binder and therefore this type of binder has been excluded from the
development of the nonwoven materials for the cigarette filter
element. The list of binders used in this stage of the development
is shown below.
TABLE-US-00008 Concentration of the supplied Supplier Binder type
Polymer solution [%] National Starch RediBOND 4000 Starch based 32
OrganoClick OC-biobinder Biopolymer based 20.4
[0164] Small-scale prototype nonwoven sheets were formed using the
sheet forming machine described in Section 2.2. A padding mangle
was used to apply a binder solution on the nonwoven sheets. The
liquid binders were diluted to 10% wt. solutions. The binder
application process is described in Section 2.3 above.
3.3 Test Methods
[0165] Tensile strength, air permeability, areal density and binder
content were evaluated using the test methods described in section
2.4. Table 4 below shows the areal density results for the four
types of nonwoven sheets listed above. The biodegradability test
was not carried out. Shorter hemp filler and shorter cotton flock
have been used in the sheets and similar binder content applied on
the sheets, therefore it is assumed that the biodegradability
performance of the nonwoven sheets of fiber compositions and binder
content shown in Table 4 below is similar to the one recorded for
the nonwoven sheets manufactured and tested in the first
development stage.
TABLE-US-00009 TABLE 4 Areal density Solider binder Sheet Fibre
composition Binder applied [g/m.sup.2] content [%] 1 20% hemp
filler 517/250 A - RediBOND (10%) 53-57 28-28.6 30% flax short cut
B- OC-biobinder (10%) 46-59 20-30.5 50% cotton flock ECD 24 2 20%
hemp filler 517/250 A - RediBOND (10%) 57-62 26.5-29 30% flax
filler B- OC-biobinder (10%) .sup. 53-59.5 17-20.sup. 50% cotton
flock ECD 24 3 50% flax short cut A - RediBOND (10%) 54-64 31.5-32
50% cotton flock ECD 24 B- OC-biobinder (10%) 54-56 20.5-22 4 50%
flax filler A- RediBOND (10%) 45.5-62.sup. 18-28.5 50% cotton flock
ECD 24 B- OC-biobinder (10%) 48-55 19-19.3
3.4 Results
3.4.1 Areal Density and Solid Binder Content
[0166] The sheet forming process described in Section 2.2 above
involves a number of operations, which influence the quality of the
final sheets. Constructing sheets from textile fibers (compared to
wood pulp) reduces the hydrogen bonding making handling of sheets
difficult and can result in some fiber loss to other surfaces. It
has a negative effect on weight variation in the individual sheets
and hence the wide range of areal densities of the individual
sheets, given in Table 4. The consequence of weight variation is
the variation in binder content on the sheets. Higher sheet weights
result in increased binder pick-up.
3.4.2 Tensile Strength
[0167] The tensile strength of the materials was evaluated to
identify their ability to withstand the cigarette filter formation
process. The results are shown in Table 5 below as well as in
graphical form in FIG. 10, together with the values obtained for
the sheets selected as the best performing materials 5S and 5L from
the first phase of the development stage, as shown in Table 4
above.
TABLE-US-00010 TABLE 5 Areal Solid Density Binder Tensile
Elongation Sheet [g/m.sup.2] Binder Content [%] Strength [N] [mm] 1
57.3 A 28.5 44.3 2.6 48.6 B 22.3 35.5 3.4 2 56.8 A 26.5 32.7 2.4
52.8 B 17.0 32.2 2.7 3 54.4 A 32.0 41.8 3.2 56.4 B 20.6 50.0 2.7 4
53.9 A 23.4 32.2 2.6 48.0 B 19.3 27.0 1.8 5S 55.9 A 27.7 33.3 3.1
59.4 B 23.6 46.1 2.9 5L 54.8 A 21.7 52.3 2.5 56.7 B 21.2 39.8
2.3
[0168] All materials show very good values of tensile strength
independent of the fiber composition and applied binder. The flax
short-cut fiber content in sheets 5L, 1, 3 results in higher values
of tensile strength compared to sheets with flax filler in the
structure (5S, 2, 4).
[0169] All sheets comprising flax fiber filler (5S, 2, 4) with
applied RediBOND.RTM. binder show similar values of the tensile
strength. The higher tensile strength of sheets 5S from the first
phase of the development stage with applied OC-biobinder compared
to the sheets 2 and 4 with the same binder can be explained by
higher areal density and slightly higher binder pick-up for the
sheets 5S. The results also show that the 20% hemp filer content in
sheet 2 does not have a negative effect on the tensile strength.
The same applies for the implementation of short cotton flock
fibers. The values of the tensile strength of the sheets comprising
the short cotton flock (2, 4) are comparable to those for sheets
with the longer cotton flock in the structure (5S).
[0170] The sheets 5L comprising flax short cut fibers/cotton flock
with long fibers (5 mm) with applied RediBOND.RTM. binder show
higher tensile strength values than sheets 1 comprising hemp
filler/flax short cut fibers/cotton flock with short fibers (0.75
mm) and sheets 3 comprising flax short cut fibers/cotton flock with
short fibers (0.75 mm). The same applies for sheets with applied
OC-biobinder. The sheets 5L comprising flax short cut fibers/cotton
flock with long fibers (5 mm) show higher tensile strength than the
sheets with hemp filler/cotton flock (0.75 mm) in the structure
(1). The sheets (3) comprising flax short cut fibers and short
cotton flock (0.75 mm) with applied OC-biobinder show higher
tensile strength than sheets with hemp filler content (1) due to
higher areal density.
3.4.3 Air Permeability
[0171] The highest values of air permeability in the range 350-430
cm.sup.3sec.sup.-15 cm.sup.-2 were obtained for sheets with applied
RediBOND.RTM. binder, as shown in FIG. 9. All sheets with
OC-biobinder applied exhibited lower air permeability values in the
range 200-270 cm.sup.3sec.sup.-15 cm.sup.-2. The results suggest
that the RediBOND.RTM. binder provided a more open structure, which
allows easier passage for the air than the sheets with applied
OC-biobinder. The variability of air permeability between sheets
with the same applied binder can be attributed to mass variation
between the individual samples.
3.5 Cigarette Filter Tip Assembly and Retention Test
[0172] Typical prior art paper cigarette filters comprise paper
filter element wrapped in a plug wrap. They are 110 mm long. In a
typical cigarette making process, these filters are cut to length
of 20 mm and used to assemble cigarettes.
[0173] Nonwoven sheets made of two different fiber blends FSC12 and
FF listed below were used to assemble rectangular samples of 33
cm.times.30 cm and prepared for the cigarette filter tip assembly
and smoking test. The fiber composition of the materials and the
rectangular sheets are shown below.
TABLE-US-00011 SHEET FIBER COMPOSITION FSC12 20% hemp filler/30%
flax short cut fibers/ 50% cotton flock FF 20% hemp filler/25% flax
filler/5% wood pulp/50% cotton flock
[0174] The rectangular sheets were embossed and then cigarette
filter tips were manually assembled. The feedback on the filter
manufacturing was received; the FF sheet material seemed to emboss
easier than the FSC12 (at the same setting) but broke apart easily
when filters were assembled. The FSC12 material broke up a bit more
on embossing but was easier to make into filters.
[0175] The results from a smoking test are shown below.
TABLE-US-00012 Development Retention Report This series of filter
samples recently received have been tested for retention as
requested. The results are given in the table below Butt NFDPM
Nicotine Tip PD Tip PD Water Sample Id Ref No. Tip Length Tip Circ
Tob Rod Length Mean Mean Mean SD Mean 2012-38456 FF Sheets 24 24
Imperial 24 mm 8 19.5 37.6 29 10.7 92.7 2012-38457 FSC Sheets 24 24
Imperial 24 mm 8 12.1 34.6 19 4.5 95.3
[0176] Filters made from FF sheets gave more inconsistent Pressure
drop (PD) readings (a larger range and more at the lower and higher
ends of its scale). Filters made from FSC12 sheets gave more
consistent PD readings within a narrower range. FIGS. 11 and 12
provide tensile strength and air permeability results for the FF
and FSC12 materials compared with the materials listed in Table 4
above.
[0177] The table below lists physical measurements from a trial
production run of a filter manufactured using materials as
described above, together with the variability analysis.
TABLE-US-00013 Measurable Sample Parameters Size Spec Mean SD C of
V % Min Max Length 20 108 108.19 0.22 0.20 107.74 108.59
Circumference (Laser) 40 24.45 24.41 0.19 0.78 24.02 24.73
Circumference Specification targets 24.02 24.88 Roundness 40 100%
95.62 1.74 1.82 89.5 97.7 Finished Weight 10 0.96 0.01 0.10 0.95
0.99 Full Rod PD 40 391 377.7 24.2 6.42 325 416 Filter Rod Hardness
10 89 93.95 1.16 1.23 92 95.5
[0178] The table below depicts a comparison of deliveries between a
commercially available cigarette using a cellulose acetate filter
and a new cigarette prototype with the same cigarette column and
using an embodiment of a filter manufactured as described above.
Both cigarettes are unventilated and have closely matched filter
pressure drop. The results show delivery of lower levels of the
non-volatiles in the new cigarette as compared to the commercially
available filter with a cellulose acetate filter.
TABLE-US-00014 Commercial New Cigarette Cigarette Mean SD Mean SD
Lit 7.8 0.2 7.2 0.3 Puffs NFDPM mg 14.8 1.0 8.5 0.5 Nicotine mg
1.20 0.04 0.55 0.04 CO mg 13.5 0.5 13.6 0.3 Water 2.5 0.6 0.8
0.2
3.6 Development
[0179] A proportion of hemp fiber filler was incorporated into the
selected blends and hence two other embodiments of fiber blends
were included in the further development; 20% hemp filler/30% flax
filler/50% cotton flock and 20% hemp filler/30% flax shot cut
fibers/50% cotton flock.
[0180] Two types of liquid binders at 10% concentration were
applied on the sheets. The solid binder content on the sheets was
in range 21.7-32% for RediBOND.RTM. binder and 17-23.6% for
OC-biobinder.
[0181] Nonwovens sheets were formed in the range of area density
48-59.4 gm.sup.-2. The range was considered quite large, however
sheets with similar area densities were selected for the tensile
and air permeability testing and therefore the results are
comparable. The weight can be reduced during scale-up trials on
full-scale or pilot wetlaid lines. Variation would also be expected
to be much lower on full-scale production equipment.
[0182] Results for tensile strength range between 27-33 N/25 mm for
samples comprising flax fiber filler (5S, 2, 4) regardless the type
of applied binder. The sheet comprising hemp fiber filler (2) shows
comparable values of the tensile strength to sheets 5S and 4.
[0183] Sheets comprising short flax fibers (5L, 1, 3) exhibit
higher tensile strength in range 35-50 N/25 mm compared with sheets
comprising flax fiber filler (5S, 2, 4). There is no noticeable
difference between sheets comprising hemp fiber filler (1) and the
other sheets (5L, 3).
[0184] The air permeability was higher for sheets with applied
RediBOND.RTM. binder than for sheets with applied OC-biobinder.
[0185] Based on the outcomes from this development stage, the
nonwoven sheets comprising 20% of hemp fiber filler provide
comparable performance parameters to those without hemp filler in
their structure. Based on the superior air permeability performance
of nonwoven sheets with applied starch based binder, RediBOND.RTM.
or other cationic starch based binder is recommended for the
application.
[0186] The results from the retention test showed low pressure drop
(PD) and retention levels for the filter element tips made of
wetlaid sheet materials. This is likely a result of the
hand-manufacturing process and perhaps not representative of a more
controlled manufacturing method. The pressure drop variation was
quite high, which may be due to the unusual nature of the filters
and the clamping method used during testing. Hand manufacturing
processes will also increase the variability in this case.
4. Pilot Line Testing
[0187] Due to the encouraging results from the cigarette filter tip
assembly trial and smoking test both FF and FSC12 materials were
used for a pilot line scale-up, along with other embodiments of
suitable cigarette filter tip materials. An alteration of FSC12
material was suggested to improve its performance during the
embossing process. It was decided to add 5% of wood pulp in the
material blend for the FSC12 composition to provide more hydrogen
bonding to the structure and reduce or prevent the shredding of the
material when exposed to the embossing process.
[0188] In some embodiments, nonwoven sheets were made from mixtures
including different blends of natural fibers, fillers or pulps as
follows: [0189] 1. Hemp fiber or filler/abaca fiber or pulp/cotton
fibers or cotton flock [0190] 2. Hemp fiber or filler/sisal fiber
or pulp/cotton fibers or cotton flock [0191] 3. Hemp fiber or
filler/abaca fiber or pulp/sisal fiber or pulp (with or without
cotton fibers or cotton flock) [0192] 4. Flax fiber filler/cotton
flock [0193] 5. Flax short cut fiber/cotton flock [0194] 6. Cotton
flock/wood pulp [0195] 7. Flax fiber filler/wood pulp [0196] 8.
Flax short cut fiber/wood pulp [0197] 9. Hemp fiber filler/cotton
flock [0198] 10. Hemp fiber filler/wood pulp
4.1 Materials
[0199] Fibers for the pilot trials were acquired from the
manufacturers STW (flax filler, flax short cut fibers, hemp
filler), Goonvean Fibers (Cotton flock), National Starch
(RediBOND.RTM.). The fiber compositions in these embodiments are
listed below in Table 24.
4.2 Processing
[0200] The wetlaid processing involved formation of the wetlaid web
and subsequent application of a liquid binder using a curtain
coating machine. The curtain coating process differs from the
mangle padding process used for binder application and could enable
production of lower density structures. An initial coating trial on
a laboratory curtain coater was carried out to simulate the binder
application process prior running the pilot line trial and identify
optimum processing conditions for obtaining the required solid
binder concentration on the wetlaid materials.
[0201] Reservoirs for fiber dispersion preparation were located at
the beginning of the pilot line. The reservoirs were filled with a
fiber suspension of a different fiber blend, as shown in Table 6
below.
TABLE-US-00015 TABLE 6 Blend Fiber composition Binder 1 20% hem
F517/250 6% RediBOND 4000 solution 25% flax short cut fibers F513/6
5% wood pulp - Sodra black 50% cotton flock ECD24 2 20% hem
F517/250 6% RediBOND 4000 solution 25% flax filler F513/400 5% wood
pulp - Sodra black 50% cotton flock ECD24
[0202] RediBOND.RTM. 4000 binder in 6% concentration was filled in
a binder reservoir (50L) and applied using a curtain coating
machine. The reservoir can be topped up during the processing to
ensure that a sufficient volume of the liquid binder is
available.
[0203] Setting of the processing parameters is based on the
experience of staff operating the wetlaid pilot line. The aim was
to obtain maximum possible length of nonwoven fabrics of area
weight 50 gm.sup.-2. Few challenges occurred during the pilot line
processing. The wetlaid fabric formed from the fiber blends as they
are shown in Table 6 with applied starch based (RediBOND.RTM.)
binder had very low strength and it was impossible to transfer the
material from the wetlaid forming wire on the conveyor to the
drying oven. In addition, the RediBOND binder at 6% concentration
was very tacky which caused further complications at the same point
on the pilot line. It was impossible to detach the wetlaid fabric
from the web forming wire.
[0204] The binder concentration was decreased to 4% to eliminate
tackiness of the binder. Simultaneously, an additional type of
fiber was integrated in the wetlaid structure to improve the wet
strength of the fabric and reduce the risk of damage to the fabric
during the transfer of the wetlaid fabric from the formation wire
to the oven conveyor. Tencel.RTM. fibers were selected as the most
suitable fibers to overcome the difficulties with the manufacturing
on the pilot line.
[0205] Tencel.RTM. fibers belong to a group of fibers made from
regenerated cellulose obtained from dissolved wood pulp.
Regenerated cellulose fibers from Lenzing, Austria represent
man-made fibers manufactured using some of the most sustainable
technology. The wet strength of Tencel.RTM. fibers is the highest
from the group of fibers made from regenerated cellulose. The
presence of Tencel.RTM. fibers (1.7 dtex, 6 mm) in the fabric
structure compensates for the lower solid binder content in the
structures caused by lower concentration of the applied binder and
hence provides strength to the dry wetlaid fabric.
[0206] Initially, 10% of Tencel.RTM. fibers were added to the chest
and a wetlaid fabric was formed. For the blend 1, the wet strength
of the wetlaid fabric was sufficient for the transfer between
forming wire and oven conveyor. However, the dry strength of the
final fabric was low. To achieve sufficient dry strength of the
fabrics without further alteration of the fiber blend, the areal
density of the material was increased to 65 g/m2.
[0207] For blend 2, an extra 5% of Tencel.RTM. fibers were added to
obtain satisfactory parameters of the wetlaid fabric.
[0208] The fiber composition in the wetlaid fabrics was calculated
and the fabric thickness measured. The results are shown in Table 7
below.
TABLE-US-00016 TABLE 7 Fiber Areal density Thickness Blend
composition Binder [g/m.sub.2] [mm] 1 (FSC12) 17.5% hemp 4%
RediBOND 65 0.96 F517/250 4000 22% flax short cut fibers F513/6 8%
wood pulp - Sodra black 44% cotton flock ECD24 8.5% Tencel .RTM.
1.7 dtex, 6 mm 2 (FF) 16.8% hemp 4% RediBOND 65 0.90 F517/250 4000
21% flax filler F513/400 7.6% wood pulp - Sodra black 42% cotton
flock ECD24 12.6% Tencel .RTM. 1.7 dtex, 6 mm
[0209] The comparison of areal density, tensile strength and air
permeability of samples with applied starch based binder
manufactured in first development phase (Section 3), in second
development phase (Section 4) and on the pilot line (Section 5) are
shown in Table 8 below.
4.3 Fabric Performance
[0210] The materials manufactured on the pilot line were subjected
to the analysis of their tensile strength and air permeability. The
results are shown below. The tensile strength test was carried out
as described in section 2.4.1 above. The tensile strength and
elongation were evaluated in machine (MD) and cross direction (CD).
Air permeability was also tested, as described in Section 2.4.4 at
pressure drop 1 mm of water column. The results for tensile
strength, elongation, and air permeability are shown in Table 14
below. The values of the tensile strength were lower than intended.
The reason was the reduced concentration of the binder, which
resulted in lower binder content on the fabrics.
[0211] Tensile strength and air permeability of the fabrics from
the pilot line trial were compared with samples manufactured during
Development phase 2 (Section 3.4) with applied RediBOND.RTM.
binder, as shown in Table 8 below.
TABLE-US-00017 TABLE 8 Areal Tensile Air Applied density strength
permeability Sample Fiber blend binder [gm.sup.2] [N/25 mm]
[cm.sup.3 sec.sup.-1 .5 cm.sup.-2] 1 20% hemp filler 10% 56 44.35
425 5017/250 RediBOND 30% flax short cut 50% cotton flock ECD24 2
20% hemp filler 10% 56.84 32.66 429.2 517/250 RediBOND 30% flax
filler 50% cotton flock ECD24 3 50% flax short cut 10% 54.42 41.81
421.4 50% cotton flock RediBOND ECD24 4 50% flax filler 10% 53.9
32.2 433.8 50% cotton flock RediBOND ECD24 FSC12 17.5% hemp filler
4% 65 MD 12.1 690 22% flax short cut RediBOND CD 7.54 8% wood pulp
44% cotton flock ECD24 FF 16.8% hemp filler 4% 65 MC 8.35 687 21%
flax filler RediBOND CD 7.54 7.6% wood pulp 42% cotton flock ECD24
12.6% Tencel fiber
[0212] Materials manufactured on the pilot line trial exhibited
lower tensile strength compared to the sheet materials due to the
lower concentration of the applied binder. The air permeability is
higher for the pilot line materials. The performance differences
are influenced by the different methods of binder application. The
wetlaid sheets are compressed between the rolls of padding mangle
during the binder application in the laboratory trials, as
described in Section 2.3. The padding roll pressure decreases the
thickness, which results in lower porosity and hence reduced void
space in the structure for transporting air. Conversely, the binder
application using a curtain coater on the pilot line results in
lower levels of compression to the fabric and therefore the final
structure is more open and allows higher volume of air to pass
through.
4.4 Cigarette Filter Tip Assembly and Smoking Test
[0213] The wetlaid rolls manufactured on the pilot line trial were
slit to different widths and subjected to filter tip manufacturing
process. The low strength materials, shown below, caused problems
during the embossing process.
TABLE-US-00018 Sheet Fiber composition FSC12 20% hemp filler/30%
flax short cut fiber/50% cotton flock FF 20% hemp filler/25% flax
filler/5% wood pulp/50% cotton flock
[0214] The FSC12 material stuck to the rollers especially in the
places where the hard pieces of flax shiv occur in the structure.
This created holes and tears in the fabric and it also indicated
possible difficulties for running this material at high speeds in a
production process. The FF material embossed much easier and did
not suffer the problem with shiv pieces sticking to the rolls.
However the material is relatively low strength and may not be
suitable in its current form for higher speeds production
processing, though it may be suitable for "roll-your-own" cigarette
making
[0215] Results from the smoking test carried out at an ISO17025
accredited smoke testing laboratory are shown in Table 9 and
provide the performance criteria (pressure drop, Nicotine
retention, Tar retention, etc.) achieved with the cigarette filters
formed from FSC12 and FF materials.
TABLE-US-00019 TABLE 9 Development Retention Report This series of
filter samples recently received have been tested for retention as
requested. The results are given in the table below Tip Tip Butt
Tip PD Tip PD Tissue Length Circ Length NFDPM Nicotine Mean SD
Water width Sample Id Ref No. mm mm Tob Rod mm Mean % Mean % mm/wg
mm/wg Mean % mm 2012-38891 D633 4895 A 24 23.8 Imperial 24 mm 8
72.9 76.6 171 9.7 95.8 150 2012-38892 D633 4895 B 24 23.8 Imperial
24 mm 8 58.7 52.9 96 6.6 93.5 130 2012-38893 D633 4895 C 24 23.8
Imperial 24 mm 8 49.5 52.3 60 5.8 89.8 110 2012-38894 D633 4895 D
24 23.8 Imperial 24 mm 8 82.3 96.7 561 21.3 99.0 220 2012-38895
D633 4897 A 24 23.8 Imperial 24 mm 8 84.6 87.4 326 13.6 97.8 180
2012-38896 D633 4897 B 24 23.8 Imperial 24 mm 8 83.1 85.0 276 12.3
95.7 160 2012-38897 D633 4897 C 24 23.8 Imperial 24 mm 8 86.3 68.0
127 9.2 92.1 130
4.5 Pilot Line Trial Conclusions
[0216] The processing of two selected fiber blends
(FSC1212--hemp/flax short cut fibers/cotton flock/wood pulp;
FF12--hemp/flax filler/cotton flock/wood pulp) with applied 6%
RediBOND.RTM. binder faced some complication during the wetlaid
processing on an industrial pilot line. The wet strength of the
wetlaid structure was too low to withstand the manufacturing
process. The high tackiness of the RediBOND.RTM. binder at 6%
concentration caused adhesion of the wetlaid fabric with applied
binder to the forming wetlaid wire. The fabric was susceptible to
tearing at the point of transfer from the wetlaid forming wire on
the conveyor to the drying oven.
[0217] Tencel.RTM. fibers were added to both fiber blends to
improve the wet strength of the wetlaid fabrics and the
concentration of RediBOND.RTM. binder was decreased to 4% to
eliminate the fabric adhesion to the forming wire. The
manufacturing of the materials with Tencel.RTM. fibers in their
structure and lower binder concentration was successful. One roll
of FSC12 and one roll of FF12 materials were produced. However, due
to low binder concentration the final dry tensile strength of the
wetlaid fabrics was lower than aimed for. Subsequently, the low
strength caused problem in embossing during the filter tip
manufacturing process.
[0218] The FSC12 sheet caused problems when embossing and stuck to
the rollers where some of the hard pieces of shiv were. This
created holes and tears in the fabric and as such it is considered
difficult to run this material at high speeds for production
purposes. The FF12 material did emboss much easier and did not
suffer from the same problem. However the material was relatively
weak and broke easily.
[0219] FSC12 material in four different widths (220, 180, 130 and
110 mm) was used to assemble cigarette filters ((D633/4695 A, B, C,
and D) and FF12 material in three different widths (180, 160 and
130 mm) was used to assemble cigarette filters (D633/4697), as
shown in Table 9. Generally, the retention and pressure drop values
are higher than those for cellulose acetate filters. The filters
made from the FSC12 narrow material 110 mm (D633 4695 C) provided
Tar and Nicotine retention, and pressure drop values close to those
achieved by very fine (1.7 dtex) cellulose acetate tow filters. The
FF12 material in 130 mm width (D633 4697 C) provides Nicotine and
tar retention slightly higher than the 1.7 dtex cellulose acetate
tow, but the pressure drop is double. The rods made from the FCS12
material in 110 mm width and FF12 material in 130 mm width are soft
in comparison to the cellulose acetate filter rods. The pressure
drop variation is comparable with that achieved by cellulose
acetate filters. Two fiber blends were selected for a pilot line
scale-up. The outcomes of pilot line trial highlighted the need to
add Tencel.RTM. fibers into the blend of natural fibers to ensure
sufficient wet strength of the fiber blends to withstand wetlaid
industrial processing.
[0220] The starch-based binder such as RediBOND.RTM. is applied in
a concentration below 6%, which results in low binder pick-up and
low strength of the final wetlaid fabric. The fabric in this form
caused problems during the cigarette filter tip manufacturing
process. To overcome this problem, starch binder may be replaced
with a different type of binder, such as carboxymethyl cellulose
binder (CMC).
[0221] From the two different fiber blends, the blend containing
flax fiber filler (FF12) is more suitable for the cigarette filter
manufacturing process.
[0222] The smoking performance of the cigarette filters made from
FSC12 material of 110 mm wide was found to be superior to other
variations tested at that time. The FF12 material in 130 mm width
provided slightly higher retention values than the cellulose
acetate tow, but double the pressure drop. The filters made of this
material were also soft.
[0223] There are two ways to decrease the retention and pressure
drop values. One way is to use shorter tip lengths in the
cigarettes which would also enhance the hardness (24 mm was chosen
as a match for Natural American Spirit filter tips). The second way
is to increase the Tencel.RTM. fiber content while decreasing the
cotton filler content. The cotton fiber filler comprises very short
and fine fibers. If cotton fiber filler is replaced by fibers of
higher diameter and length, such as regenerated cellulose fibers, a
filter structure of higher porosity which has improved ability to
conduct air (cigarette smoke) may be produced. Regenerated
cellulose fibers also have smaller specific surface compared to the
cotton flock fiber filler which may further decrease Nicotine and
tar retention values.
[0224] Overall, the FF material was considered more suitable for
the cigarette assembly processing due to the improved embossing
performance. The wet strength of the material during the wetlaid
processing as well as dry strength of the final wetlaid product may
be improved by suitable choice of materials and processing steps.
In one embodiment wet strength is improved by adding regenerated
cellulose fibers such as Tencel.RTM. fibers in the fiber blend; dry
strength is improved by increasing binder pick-up on the materials,
for example by using a higher concentration of a different type of
binder obtained from natural sources such as carboxymethyl
cellulose.
[0225] In one embodiment, the cotton fiber flock fibers in the
filter compositions listed for samples FSC12 and FF12 may be
replaced with coarser regenerated cellulose fibers in the
structure, to increase porosity as well as air permeability. Other
biodegradable fiber mixtures may be used in alternative
embodiments, as discussed in more detail below.
[0226] In one embodiment, filter compositions of materials in the
following % ranges may be used for production of a biodegradable
filter element: [0227] 0-25% by weight hemp fiber short cut fibers
or hemp filler, [0228] 0-25% by weight flax fiber short cut or flax
fiber flock, [0229] 0-55% of abaca fiber or abaca pulp, [0230]
0-55% of sisal fibers or sisal pulp, [0231] 0-40% of regenerated
cellulose fibers, [0232] 0-50% of wood pulp, [0233] 0-20% cotton
fibers or cotton flock, and [0234] 0-20% of a natural binder (e.g.
liquid starch extracted from plant sources or a water soluble
biodegradable polymer material such as carboxymethyl cellulose). If
the binder is not included, the proportion of the other components
remains the same, but a heavier web is manufactured (60 gsm or
grams per square meter) using a hydroentanglement process.
Currently the web weight with binder is approximately 50 gsm+added
binder (around 10 gsm)=total weight 60 gsm.
5. Additional Embodiments
[0235] Tables 10 to 16 below list the material compositions of the
FF12 and FSC12 cigarette filter nonwoven substrate materials
described above and some additional examples of nonwoven material
substrate compositions suitable for cigarette filters. The material
codes used in Tables 10 to 16 are listed below in Table 9A.
TABLE-US-00020 TABLE 9A List of tested material codes Material code
Machine FF12 Pilot line FSC12 Pilot line FF13 Pilot line FF_Feb14
Pilot line AB_Feb14 Pilot line FF_Mar14 Industrial line AB_Oct14
Industrial line AB_Dec14 Industrial line FE1-FE4 Sheet former
FE5-FE6 Sheet former FE7 Sheet former V1-V6 Sheet former V7(H)
Sheet former V8-V9 Sheet former
TABLE-US-00021 TABLE 10 Fibre composition Fibre type/Fibre
parameters Binder added FF12 FSC12 FF13 FF14_Feb14 AB_Feb14 Flax
21% Flax filler 21% Flax short 25% Flax fibre 25% Flax fibre 25%
Abaca pulp 2.5 mm cut 5 mm 2.5 mm Beater trial to 6 mm 25SR Pulp
Specialties Hemp 17% Hemp 17.5% Hemp 20% Hemp 20% Hemp flock 20%
Hemp flock filler filler flock 1.5 mm 1.5 mm 1.5 mm 1.5 mm 0.25 mm
Wood pulp 8% Sodra 8% Sodra black 5% Sodra black 5% Sodra black 5%
Sodra black black beater trial to beater trial to beater trial to
beater trial to beater trial to 25SR 25SR 25SR 25SR 25SR Cotton 42%
Cotton 42% Cotton 15% Cotton 15% Cotton flock 15% Cotton flock
flock flock 0.75 mm flock 0.75 mm 0.75 mm 0.75 mm 0.75 mm Tencel
12% Tencel 12% Tencel 35% Tencel 35% Tencel 35% Tencel 6 mm 6 mm 6
mm 6 mm 6 mm Binder Cationic starch Cationic starch Cationic starch
Cationic starch Cationic starch 10-15% wt 10-15% wt. 10-15% wt
10-15% wt. 15-20% wt
TABLE-US-00022 TABLE 11 Fibre composition Fibre type/Fibre
parameters Binder added FF_Mar14 AB_Oct14 AB_Dec14 Flax 25% Flax
filler -- -- 2.5 mm Hemp 20% Hemp flock 5% Hemp flock 14.5% Hemp
flock 1.5 mm 1 mm 1 mm Pulp 5% Sodra black 45% Abaca 33% Abaca
beater trial to beater trial to beater trial to 25SR 27SR 21-25 SR
Cotton 15% Cotton flock 15% Cotton flock 19.5% Cotton flock 0.75 mm
0.75 mm 0.75 mm Tencel 35% Tencel 35% Tencel 33% Tencel 6 mm 6 mm 6
mm Binder Cationic starch Cationic starch Cationic starch 10-15% wt
15-20% wt 2-3% wt and 8-10% wt
TABLE-US-00023 TABLE 12 Fibre composition Fibre type/Fibre
parameters Binder added FE1 FE2 FE3 FE4 Flax 25% Flax filler 25%
Flax filler 25% Flax filler 25% Flax filler 2.0 mm 2.0 mm 2.0 mm
2.0 mm Hemp 20% Hemp filler 20% Hemp filler 20% Hemp filler 20%
Hemp filler 1.5 mm 1.5 mm 1.5 mm 1.5 mm Wood pulp 5% Sodra black 5%
Sodra black 5% Sodra black 5% Sodra black beater trial to 25SR
beater trial to 25SR beater trial to 25SR beater trial to 25SR
Cotton 50% Cotton flock 25% Cotton flock -- 35% Cotton flock 0.75
mm 0.75 mm 0.75 mm Tencel -- 25% Tencel 50% Tencel 15% Tencel 6 mm
6 mm 6 mm Binder Cationic starch I Cationic starch I Cationic
starch I Cationic starch I Cationic starch II Cationic starch II
Cationic starch II Cationic starch II
TABLE-US-00024 TABLE 13 Fibre composition Fibre type/Fibre
parameters Binder added FE5 FE6 FE7 Flax 25% Flax short 25% Flax
short 25% Flax short cut quality A cut quality B cut quality A 3.5
mm 5 mm 3.5 mm Hemp 20% Hemp 20% Hemp 20% Hemp filler filler filler
1.7 mm 1.7 mm 1.7 mm Wood pulp 5% Sodra black 5% Sodra black 5%
Sodra black beater trial beater trial beater trial to 25SR to 25SR
to 25SR Cotton 25% Cotton 25% Cotton 15% Cotton flock flock flock
0.75 mm 0.75 mm 0.75 mm Tencel 25% Tencel 25% Tencel 35% Tencel 6
mm 6 mm 6 mm Binder Cationic Cationic Cationic starch starch
starch
TABLE-US-00025 TABLE 14 Fibre composition Fibre type/Fibre
parameters Binder added V1 V2 V3 V4 Hemp 10% Hemp 5% Hemp 10% Hemp
10% Hemp filler filler filler filler 1.5 mm 1.5 mm 1.5 mm 1.5 mm
Pulp 40% Abaca 45% Abaca 55% Abaca 25% Abaca beater trial beater
trial beater trial beater trial to 21SR to 21SR to 21SR to 21SR
Cotton 15% Cotton 15% Cotton -- 30% Cotton flock flock flock 0.75
mm 0.75 mm 0.75 mm Tencel 35% Tencel 35% Tencel 35% Tencel 35%
Tencel 6 mm 6 mm 6 mm 6 mm Binder Cationic Cationic Cationic
Cationic starch starch starch starch
TABLE-US-00026 TABLE 15 Fibre composition Fibre type/Fibre
parameters Binder added V5 V6 Hemp 10% Hemp filler 10% Hemp filler
1.5 mm 1.5 mm Sisal pulp 40% Sisal pulp -- beater trial to 21SR
Sisal fibre -- 40% Sisal short cut 2.0 mm Cotton 15% Cotton flock
15% Cotton flock 0.75 mm 0.75 mm Tencel 35% Tencel 35% Tencel 6 mm
6 mm Binder Cationic starch Cationic starch
TABLE-US-00027 TABLE 16 Fibre composition Fibre type/Fibre
parameters Binder added V7(H) V8 V9 Hemp 5% Hemp 10% Hemp 20% Hemp
filler filler filler 1.5 mm 1.5 mm 1.5 mm Abaca pulp 45% Abaca 35%
Abaca 30% Abaca beater trial beater trial beater trial to 27SR to
27SR to 27SR Cotton 15% Cotton 20% Cotton 15% Cotton flock flock
flock 0.75 mm 0.75 mm 0.75 mm Tencel 35% Tencel 35% Tencel 35%
Tencel 6 mm 6 mm 6 mm Binder Cationic Cationic Cationic starch
starch starch
[0236] Some important parameters for cigarette filter materials are
discussed below.
Areal Density (gm-2) and Mass Uniformity (%)
[0237] The areal density of the product can vary from 25 gm.sup.-2
to 65 gm.sup.-2. The optimum areal density is selected to comply
with the cigarette filter converting process and provide required
smoking performance.
[0238] Mass uniformity of the material is at least <10%, and may
be <5%, or <1%.
Volume Density
[0239] Relatively low volume density provides open and bulky
structure of the fibrous material. The volume density is at least
<200 kgm.sup.-3, and may be <150 kgm.sup.-3, or <100
kgm.sup.-3.
Air Permeability
[0240] The open bulky structure allows the air to pass relatively
easy through the plane of the material. Desirable air permeability
measured at differential pressure 200 Pa (Pascals) is at least
[0241] >20 cm.sup.3cm.sup.-2sec.sup.-1, and best results are
achieved with air permeability >100 cm.sup.3cm.sup.-2sec-1, or
>200 cm.sup.3cm.sup.3cm.sup.-2sec.sup.-1.
Tensile Strength
[0242] Tensile strength in the cigarette filter manufacturing
process is not below 20N (Newton) for 25 mm wide material measured
in the machine direction.
Wet Strength
[0243] Sufficient wet strength is important during the material
processing (web forming, web bonding, drying). The wet strength
depends on the machinery selected for the product
manufacturing.
Dispersibility
[0244] The aim is for provide material which complies with Guidance
Document for Flushability of Nonwoven Consumer Products issued by
the European Disposables and Nonwovens Association (EDANA) in 2009.
The materials listed in Tables below were evaluated using
Dispersibility Shake Flask Test (FG511.1 Tier1)--Assessment of the
rate and extent of disintegration of a test material in the
presence of tap water. The use of orbital floor shaked capable of
150 rpm with clamps suitable for 2800 mL Fernbach triple-baffled,
glass flasks is required. The material of mass 1-2 g is placed in a
flask and 1 L of tap water added. The flask with the material is
exposed to agitation at 150 rpm for 1 hour. After the end of the
agitation, the flask is removed and the entire content of a single
flask poured through a nest of screens arranged from to top to
bottom in the following order: Aperture size (diameter of opening)
12 mm, 6 mm, 3 mm, 1.5 mm. The material is gently rinsed with hand
held shower head held approximately 10-15 cm above the top screen
for 2 minutes at water flow rate is 4 L/minute. After two minutes
of rinsing, the top screen is removed and the rinse continues on
the next screen for additional two minutes. This rinsing process
continues until all of the screens have been rinsed. The retained
material on the individual screens is removed, transferred onto a
drying pan and dried in an oven. The percentage of the
disintegrated test product retained on the individual screens is
calculated from the initial test sample dry mass and the dry mass
of the material proportion retained on the individual screens.
[0245] According to the flushability guidelines, a material is
recommended for the Risk Assessment for Chemical Substances for
flushability, landfill and incinerator disposal when 95% of its
initial mass passes through the 12 mm screen.
Soil Burial Test
[0246] AATCC Test Method determines the soil burial test for
materials in direct contact with soil. The test assesses the loss
in tensile strength as a consequence of textile deterioration as a
result of fungal growth. The method involves exposure to the fungal
activity in a soil bed for several days. The soil bed activity is
considered satisfactory if cotton woven cloth of 271 gm.sup.-2
looses 90% of its tensile strength in seven days exposure. [0247]
Soil bed--optimum moisture content 25.+-.5% of dry weight, air
relative humidity above 83.+-.3% rh, soil bed height 10.+-.1 cm.
[0248] Specimen--dimensions 75 mm.times.25 mm, space the specimen
at least 2.5 cm apart, cover with 2.5.+-.0.5 cm of soil bed. [0249]
Tensile test--gauge length set to 75% of the original length,
loading speed 100 mmmin.sup.-1.
[0250] The above parameters were measured for the compositions
listed in Tables 10 to 16. The measured parameters are provided in
the following Tables 17 to 22. Note that modified versions of
compositions V1 to V5 and V7 to V9 were produced with different
areal densities as well as versions with no binder and with
different binder content, and test results for these alternatives
are listed in Tables 20 and 21.
TABLE-US-00028 TABLE 17 Areal Volume Tensile strength density
Thickness density Air permeability* [N/25 mm] Material [g m.sup.-2]
[mm] [kg m.sup.-2] [cm.sup.-2 cm.sup.-2 sec.sup.-1] MD CD FF12 65
0.79 82.3 216 8.35 6.59 FSC12 65 0.80 81.25 205 12.10 7.54 FF13 61
0.655 93.1 292 23.3 18.5 FF_Feb14 62 0.805 77.0 315 26.0 26.6
AB_Feb14 62 0.69 89.9 157 60.7 47.8 FF_Mar14 60.5 0.75 80.7 260 50
27 AB_Oct14 36.0-41.7 0.30 133.3 192 50.0-63.9 28.0-35.5 AB_Dec14
29.5 0.315 93.7 239 30.9 21.0 *Air permeability measured at 200
Pa
TABLE-US-00029 TABLE 18 Areal Binder Tensile density content
strength Air permeability Material Binder applied [g m.sup.-2] [%]
[N/25 mm] [cm.sup.3 cm.sup.-2 sec.sup.-1] FE1 4% Cationic starch I
54.9 8.9 11.05 122 no Tencel 4% Cationic starch II 55.7 8.0 10.9
118 fibres 6% Cationic starch I 61.5 18.1 26.75 97.1 6% Cationic
starch II 60.8 14.5 16.05 103 FE4 4% Cationic starch I 59.0 11.26
31.9 114 15% Tencel 4% Cationic starch II 58.3 12.3 31.6 107 fibres
6% Cationic starch I 61.5 17.0 31.7 104.5 6% Cationic starch II
62.4 17.3 42.7 106.5 FE2 4% Cationic starch I 61.5 12.1 48.8 110.5
25% Tencel 4% Cationic starch II 59.4 10.1 33.6 121.5 fibres 6%
Cationic starch I 62.8 17.7 46.7 110.4 6% Cationic starch II 63.5
15.4 48.45 108 FE4 4% Cationic starch I 59.1 14.0 54.9 156 50%
Tencel 4% Cationic starch II 59.8 12.6 52.8 136 fibres 6% Cationic
starch I 66.9 18.8 73.75 129.5 6% Cationic starch II 63.9 20.8
70.85 128 *Air permeability measured at 200 Pa
TABLE-US-00030 TABLE 19 Areal Solid binder Tensile Air density
content strength permeability Material [g m.sup.-2] [%] [N/25 mm]
[cm.sup.3 cm.sup.-2 s.sup.-1] FE5 57.3 13.6 39.8 93.2 FE6 N/A FE7
55.0 12.5 43.7 132.0 *Air permeability measured at 200 Pa
TABLE-US-00031 TABLE 20 Areal Binder Air perme- Tensile density
content ability at 200 strength Material [g m.sup.-2] [% wt] Pa
[cm.sup.3 cm.sup.-2 sec.sup.-1] [N/25 mm] V1_40 40.4 -- 117.5 16.05
V1_40_B 43.4 17.2 107.0 74.7 V1_60 62.3 -- 57.25 26.05 V1_60_B 56.6
15.3 60.1 101.05 V2_40 39.2 -- 85.85 17.6 V2_40_B 41.9 19.2 84.0
80.75 V2_60 60.2 -- 63.5 28.05 V2_60_B 60.3 15.3 52.1 120.5 V3_40
43.0 -- 67.35 28.95 V3_40_B 42.6 20.3 60.85 80.05 V3_60 60.2 --
38.60 44.75 V3_60_B 64.8 17.2 37.35 140.6 V4_40 40.0 -- 121.5 6.1
V4_40_B 42.3 18.5 139.5 56.55 V4_60 59.7 -- 83.75 13.0 V4_60_B 64.0
16.6 76.05 92.60 V5_40 40.0 -- 123.5 15.8 V5_40_B 44.6 18.9 120.0
60.4 V5_60 59.8 -- 70.75 24.55 V5_60_B 63.05 15.1 70.30 93.3 V6
N/A
TABLE-US-00032 TABLE 21 Air perme- Areal Binder ability at 200
Tensile strength density content Pa [cm.sup.3 cm.sup.-2 [N/25 [N/15
Material [g m.sup.-2] [% wt] sec.sup.-1] mm] mm] V7_40 35.3 -- 67.1
17.8 10.3 V7_40_B2 37.4 9.7 66.3 54.1 32.5 V7_40_B6 38.9 18.7 75.3
59.3 35.6 V8_40 37.2 -- 102.0 12.3 7.4 V8_40_B2 39.2 11.6 116.3
46.4 27.8 V8_40_B6 40.9 20.0 113.3 60.9 36.5 V9_40 42.2 -- 122.5
9.3 5.6 V9_40_B2 43.8 10.4 128.8 52.6 31.6 V9_40_B6 47.5 21.6 104.5
66.9 40.2 V8_30 34.6 -- 102.7 12.5 7.6 V8_30_B2 35.7 10.5 121.2
48.3 29.0 V8_30_B6 39.6 23.8 101.1 61.9 37.12 V9_30 34.5 -- 132.5
9.5 5.7 V9_30_B2 36.8 11.0 144 48.0 28.8 V9_30_B6 40.8 23.0 123.3
57.6 34.5
The results in Tables 17 to 21 show that the tested filter
materials have the desired open and bulky structure and air
permeability parameters.
[0251] Material dispersibility results are listed in Table 22
below.
TABLE-US-00033 TABLE 22 Shake flask test for 1 hour agitation
Material passing Material passing 12 mm screen 3 mm screen Material
[%] [%] FF_March14 100.00 99.76 AB_Oct14 100.00 89.76 AB_Dec14
99.78 99.78 V1_60_B 100.00 100.00 V3_60_B 100.00 99.65 V4_60_B
99.69 99.69 V2_40 100.00 100.00 V2_40_B2 100.00 99.34 V2_40_B6
100.00 100.00 V7_40 100.00 100.00 V7_40_B2 100.00 100.00 V7_40_B6
100.00 100.00 V8_40 100.00 100.00 V8_40_B2 100.00 100.00 V8_40_B6
100.00 100.00 V9_40 100.00 100.00 V9_40_B2 100.00 100.00 V9_4_B6
100.00 100.00 V8_30 100.00 100.00 V8_30_B2 100.00 100.00 V8_30_B6
100.00 100.00 V9_30 100.00 100.00 V9_30_B2 100.00 100.00 V9_30_B6
100.00 100.00
[0252] The materials listed in Table 22 meet dispersibility
requirements since the percentages of disintegrated test product
remaining on a 3 mm screen following the dispersibility test
described above is minimal to zero, and the materials disintegrated
rapidly under wet conditions. Soil burial tests were also carried
out on the above sample materials. All samples had a tensile
strength lower than 90% of the original value after three to five
days exposure to the fungal activity in a soil bed.
[0253] The compositions with lower hard fiber content, i.e.
examples VI-V5 and V7-V9 of Tables 14 to 16, 20 and 21 which have a
lower amount of hemp (or flax) provide improved processing and
uniformity in the end product and thus work well in a biodegradable
cigarette filter tow.
[0254] The biodegradable cigarette filter materials described above
provide good smoking performance and are made of all natural and
compostable materials which are readily biodegradable when
cigarette butts are discarded outdoors. The filter material may be
used in cigarette manufacture or supplied to customers for use in
rolling their own cigarettes.
[0255] The above description of the disclosed embodiments is
provided to enable any person skilled in the art to make or use the
invention. Various modifications to these embodiments will be
readily apparent to those skilled in the art, and the generic
principles defined herein can be applied to other embodiments
without departing from the spirit or scope of the invention. Thus,
the invention is not intended to be limited to the embodiments
shown herein but is to be accorded the widest scope consistent with
the principles and novel features disclosed herein.
* * * * *