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Patent 2281802 Summary

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(12) Patent: (11) CA 2281802
(54) English Title: CELLULOSE-BINDING FIBRES
(54) French Title: FIBRES SE LIANT A LA CELLULOSE
Status: Expired and beyond the Period of Reversal
Bibliographic Data
(51) International Patent Classification (IPC):
  • D04H 1/54 (2012.01)
  • D01F 8/06 (2006.01)
(72) Inventors :
  • HANSEN, PIA HOLM (Denmark)
  • LARSEN, ANNE MONRAD (Denmark)
(73) Owners :
  • FIBERVISIONS A/S
(71) Applicants :
  • FIBERVISIONS A/S (Denmark)
(74) Agent: GOWLING WLG (CANADA) LLP
(74) Associate agent:
(45) Issued: 2005-05-24
(86) PCT Filing Date: 1998-03-31
(87) Open to Public Inspection: 1998-10-15
Examination requested: 2001-08-27
Availability of licence: N/A
Dedicated to the Public: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/DK1998/000131
(87) International Publication Number: WO 1998045519
(85) National Entry: 1999-08-24

(30) Application Priority Data:
Application No. Country/Territory Date
0394/97 (Denmark) 1997-04-08

Abstracts

English Abstract


The invention relates to drylaid nonwoven materials comprising bicomponent
fibres comprising a low melting polyolefin component
and a high melting polyolefin component, the low melting polyolefin component
constituting at least a part of the surface of the fibre and
comprising a non-grafted polyolefin component and a grafted polyolefin
component, wherein the grafted polyolefin component has been
grafted with an unsaturated dicarboxylic acid or an anhydride thereof, e.g.
with maleic acid or maleic anhydride. The bicomponent fibres
have an excellent bonding affinity for natural fibres such as cellulose pulp
fibres and allow the production of airlaid nonwovens with reduced
generation of dust during the production process and with improved nonwoven
strength properties.


French Abstract

La présente invention concerne des matériaux non tissés obtenus à sec, comprenant des fibres à deux composants constituées d'un composant polyoléfine à point de fusion bas et d'un composant polyoléfine à point de fusion élevé. Le composant polyoléfine à point de fusion bas constitue au moins une partie de la surface de la fibre et comprend un composant polyoléfine non greffé et un composant polyoléfine greffé, lequel a été greffé avec un acide dicarboxylique insaturé ou un anhydride de celui-ci, par exemple, un acide maléique ou un anhydride maléique. Les fibres à deux composants présentent une excellente affinité de liaison pour des fibres naturelles telles que des fibres de pulpe de cellulose et permettent la production de non-tissés formés par jet d'air, la production de poussière étant réduite pendant le procédé de production et les propriétés de résistance des non-tissés étant améliorées.

Claims

Note: Claims are shown in the official language in which they were submitted.


1
CLAIMS
1. A drylaid nonwoven material comprising bicomponent fibres each fibre
comprising:
A) a high melting polyolefin component; and
B) a low melting polyolefin component
1) having a melting point at least 4°C lower than the melting point of
said
high melting polyolefin component,
2) constituting at least a part of the surface of said bicomponent fibre, and
3) comprising a non-grafted polyolefin component and a grafted polyolefin
component
a) wherein said grafted polyolefin component has been grafted with
an unsaturated dicarboxylic acid or an anhydride thereof.
2. A drylaid nonwoven material according to claim 1 wherein the grafted
polyolefin
component of the bicomponent fibres has been grafted with a compound selected
from
the group consisting of: maleic acid, maleic anhydride and derivatives
thereof; fumaric
acid and derivatives thereof; unsaturated derivatives of malonic acid; and
unsaturated
derivatives of succinic acid.
3. A drylaid nonwoven material according to claim 2 wherein the grafted
polyolefin
component of the bicomponent fibres has been grafted with a compound selected
from
the group consisting of citraconic acid, citraconic anhydride, pyrocinchonic
anhydride, 3
butene-1,1-dicarboxylic acid, benzylidene malonic acid, isopropylidene malonic
acid,
itaconic acid and itaconic anhydride.
4. A drylaid nonwoven material according to claim 2 wherein the grafted
polyolefin
component of the bicomponent fibres has been grafted with maleic acid or
maleic
anhydride.

2
5. A drylaid nonwoven material according to claim 1 wherein the bicomponent
fibres are
sheath-core fibres in which the lower melting polyolefin component constitutes
the sheath
and the high melting polyolefin component constitutes the core.
6. A drylaid nonwoven material according to claim 1 which further comprises at
least one
additional fibrous material.
7. A drylaid nonwoven material according to claim 6 wherein the additional
fibrous
material is selected from the group consisting of cellulose fibres, viscose
fibres and
Lyocell fibres.
8. A drylaid nonwoven material according to claim 6 wherein the additional
fibrous
material comprises cellulose fluff pulp fibres.
9. A drylaid nonwoven material according to claim 1 wherein the high melting
polyolefin
component comprises polypropylene and the low melting polyolefin component
comprises
at least one polyolefin selected from LLDPE, HDPE and LDPE.
10. A drylaid nonwoven material according to claim 1 wherein the difference in
melting
points between the low melting component and the high melting component of the
bicomponent fibres is at least about 20°C.
11. A drylaid nonwoven material according to claim 1 wherein the high melting
polyolefin
component comprises a first polypropylene, and the low melting polyolefin
component
comprises a second polypropylene or a polypropylene copolymer with a melting
point at
least 5°C lower than the first polypropylene.
12. A method for producing a drylaid nonwoven material, comprising forming a
fibrous
web using dry lay nonwoven equipment, the web comprising bicomponent fibres
each
fibre comprising:
A) a high melting polyolefin component; and
B) a low melting polyolefin component
1) having a melting point at least 4°C lower than the melting point of
said
high melting polyolefin component,
2) constituting at least a part of the surface of said bicomponent fibre, and

3
3) comprising a non-grafted polyolefin component and a grafted polyolefin
component
a) wherein said grafted polyolefin component has been grafted with
an unsaturated dicarboxylic acid or an anhydride thereof,
and bonding the fibrous web to result in the drylaid non woven material.
13. A method according to claim 12, wherein the fibrous web further comprises
at least
one additional fibrous material.
14. A method according to claim 13 wherein the additional fibrous material is
selected
from the group consisting of cellulose fibres, viscose fibres and Lyocell
fibres.
15. A method according to claim 13 wherein the additional fibrous material
comprises
cellulose fluff pulp fibres.
16. A method according to claim 12 wherein the grafted polyolefin component of
the
bicomponent fibres has been grafted with a compound selected from the group
consisting
of: maleic acid, maleic anhydride and derivatives thereof; fumaric acid and
derivatives
thereof; unsaturated derivatives of malonic acid; and unsaturated derivatives
of succinic
acid.
17. A method according to claim 16 wherein the grafted polyolefin component of
the
bicomponent fibres has been grafted with a compound selected from citraconic
acid,
citraconic anhydride, pyrocinchonic anhydride, 3-butene-1,1-dicarboxylic acid,
benzylidene malonic acid, isopropylidene malonic acid, itaconic acid and
itaconic anhydride.
18. A method according to claim 16 wherein the grafted polyolefin component of
the
bicomponent fibres has been grafted with maleic acid or maleic anhydride.
19. A method according to claim 12 wherein the bicomponent fibres are sheath-
core fibres
in which the lower melting polyolefin component constitutes the sheath and the
high
melting polyolefin component constitutes the core.

4
20. A method according to claim 12 wherein the high melting polyolefin
component
comprises polypropylene and the low melting polyolefin component comprises at
least
one polyolefin selected from LLDPE, HDPE and LDPE.
21. A method according to claim 12 wherein the difference in melting points
between the
low melting component and the high melting component of the bicomponent fibres
is at
least about 20°C.
22. A method according to claim 12 wherein the high melting polyolefin
component
comprises a first polypropylene and the low melting polyolefin component
comprises a
second polypropylene or a polypropylene copolymer with a melting point at
least 5°C
lower than the first polypropylene.
23. A bicomponent fibre for the production of drylaid nonwoven materials, the
fibre
comprising:
A) a high melting polyolefin component; and
B) a low melting polyolefin component
1) having a melting point at least 4°C lower than the melting point of
said
high melting polyolefin component,
2) constituting at least a part of the surface of said bicomponent fibre, and
3) comprising a non-grafted polyolefin component and a grafted polyolefin
component
a) wherein said grafted polyolefin component has been grafted with
an unsaturated dicarboxylic acid or an anhydride thereof.
24. A drylaid nonwoven material comprising bicomponent fibres as defined in
claim 1 and a
natural or regenerated fibrous material, the bicomponent fibres having a
bonding affinity to the
natural or regenerated fibres such that the nonwoven material shows a dust
value in the
standardised dust test described herein of less than about 15 mg.

5
the bicomponent fibres having a bonding affinity to the natural or regenerated
fibres such
that the nonwoven material shows a dust value in the standardised dust test
described
herein of not more than about 10 mg.

Description

Note: Descriptions are shown in the official language in which they were submitted.


CA 02281802 1999-08-24
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1
CELLULOSE-BINDING FIBRES
FIELD OF THE INVENTION
The present invention relates to drylaid nonwoven materials
comprising polyolefin bicomponent fibres having excellent
bonding affinity for natural fibres such as cellulose fibres.
BACKGROUND OF THE INVENTION
Hygienic absorbent products such as disposable diapers con-
tain, in addition to a water-permeable coverstock, a water-
impermeable backsheet and one or more layers for distribution
of liquid, an absorbent core typically comprising natural fi-
tires such as cellulose fluff pulp fibres, synthetic fibres
based on e.g. polyolefin and/or polyester and a superabsorb-
ent polymer (SAP) material. In absorbent cores of this type,
the synthetic fibres, which often are bicomponent fibres of
e.g. polypropylene/polyethylene or polyester/polyethylene,
are thermobonded to each other to form a supporting network
for the core. Ideally, the synthetic fibres should be able to
not only bond to each other, but also to the natural fibres
and the SAP, so as to result in a core structure which is as
strong and coherent as possible, and in which the natural fi-
tires and the SAP are locked into place within the structure.
However, the existing synthetic fibres that are used for the
production of drylaid, e.g. airlaid, nonwovens suffer from
the disadvantage of suboptimal bonding to e.g. cellulose fi-
tires. The problem is made worse by the fact that the natural
fibres are typically relatively short, e.g. fluff pulp fibres
with a length of not more than about 3 mm, as compared to the
synthetic fibres, which are normally (although not necessar-
ily) considerably longer. As a result, dust problems are cre-
ated in the manufacturing process, and the performance of the
resulting nonwovens is also suboptimal, since a large propor-
.___..v____ __._. ~_ ~._..~.__~ .~_._.._. ~

p I II
CA 02281802 1999-08-24
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2
tion of the natural fibres is not bonded to any of the syn-
thetic fibres or otherwise held in place by means of the
structure formed by bonding of the synthetic fibres.
It is therefore an object of the present invention to provide
a bicomponent synthetic fibre which has an improved bonding
affinity for natural fibres such as cellulose fluff pulp fi-
bres and which therefore is particularly suitable for the
production of drylaid nonwovens comprising a mixture of syn-
thetic fibres and natural fibres.
EP 0465203-Bl discloses thermally bonded fibrous wet laid
webs containing bicomponent fibres comprising a first compo-
nent of polyester, polyamide or polypropylene and a second
component of linear low density polyethylene (LLDPE) with a
density of 0.88-0.945 g/cc and a grafted high density poly-
ethylene (HDPE) with a density of 0.94-0.965 g/cc which has
been grafted with malefic acid or malefic anhydride to provide
succinic acid or succinic anhydride groups along the HDPE
polymer.
EP 0421734-Bl discloses thermobondable bicomponent fibres
composed of two different polyolefins having melting points
which differ by at least 20°C, the lower melting polyolefin
containing 3-loo by weight of a monoglyceride of a fatty acid
of 12 or more carbon atoms incorporated therein. The fibres
are reported to be easily processable without the need for an
oiling agent to be applied during spinning or drawing.
US 4,950,541 discloses succinic acid and succinic anhydride
grafts of linear ethylene polymers obtained by grafting
malefic acid or malefic anhydride onto a LDPE (low density
polyethylene), LLDPE or HDPE polymer. The grafted polymers
are dyeable and can be used e.g. as the sheath component of a
bicomponent fibre.
_...T . _.____. . T _

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3
US 4,684,576 discloses the production of blends of grafted
HDPE with ungrafted LLDPE or LDPE, the HDPE having been
grafted with malefic acid or malefic anhydride to provide suc-
cinic acid or succinic anhydride groups along the HDPE poly-
mer. The blends are disclosed for use in producing laminate
structures.
It has now unexpectedly been found that polyolefin bicompo-
nent fibres whose low melting component comprises a non-
grafted polyolefin component and a grafted polyolefin compo-
nent which has been grafted with an unsaturated dicarboxylic
acid or an anhydride thereof have advantageous properties
when used in the production of drylaid nonwoven materials,
including improved bonding to cellulose pulp fibres and im-
proved strength properties in the resulting nonwovens.
BRIEF DISCLOSURE OF THE INVENTION
In one aspect, the present invention relates to a drylaid
nonwoven material comprising bicomponent fibres comprising a
low melting polyolefin component and a high melting polyole-
fin component, wherein the low melting polyolefin component
has a melting point at least 4°C lower than the melting point
of the high melting polyolefin component, the low melting
polyolefin component constituting at least a part of the sur-
face of the fibre and comprising a non-grafted polyolefin
component and a grafted polyolefin component, wherein the
grafted polyolefin component has been grafted with an unsatu-
rated dicarboxylic acid or an anhydride thereof.
Another aspect of the invention relates to a method for pro-
ducing a drylaid nonwoven material, comprising forming a fi-
brous web using dry lay nonwoven equipment, the web compris-
ing bicomponent fibres comprising a low melting polyolefin
component and a high melting polyolefin component, wherein
the low melting polyolefin component has a melting point at
..__..._

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4
least 4°C lower than the melting point of the high melting
polyolefin component, the low melting polyolefin component
constituting at least a part of the surface of the fibre and
comprising a non-grafted polyolefin component and a grafted
polyolefin component, wherein the grafted polyolefin compo-
nent has been grafted with an unsaturated dicarboxylic acid
or an anhydride thereof, and bonding the fibrous web to re-
sult in the drylaid nonwoven material.
A further aspect of the invention relates to a bicomponent
fibre as described above for the production of drylaid non-
woven materials.
DETAILED DISCLOSURE OF THE INVENTION
The term "polyolefin component" for the purpose of this in-
vention means a polyolefin-containing polymeric material of
which the largest part (by weight) consists of homo- or co-
polymers of monoolefins such as ethylene, propylene, 1-bu-
tene, 9-methyl-1-pentene, etc. Examples of such polymers are
isotactic or syndiotactic polypropylene, polyethylenes of
different densities, such as high density polyethylene, low
density polyethylene and linear low density polyethylene and
blends of the same. The polymeric material may be mixed with
other non-polyolefin polymers such as polyamide or polyester,
provided that polyolefins still constitute the largest part
of the composition. The melts used to produce the polyolefin-
containing fibres may also contain various conventional fibre
additives, such as calcium stearate, antioxidants, process
stabilizers, compatibilizers and pigments, including whiten-
ers and colourants such as TiOz, etc.
Although the present description will for the sake of sim-
plicity generally refer to "fibres", i.e. cut staple fibres,
it is to be understood that the present invention will also
j

CA 02281802 1999-08-24
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be applicable to the production of continuous polyolefin
filaments, e.g. spunbonded filaments.
The term "drylaid" nonwoven refers to a nonwoven material
5 produced by a dry process, including airlaid nonwovens,
carded nonwovens., etc.
The bicomponent fibres may be of the sheath-core type with
the core being located either eccentrically (off-center) or
concentrically (substantially in the center), or of the side-
by-side type, in iahich each of the two components typically
has a semi-circle cross section. Bicomponent fibres having
irregular fibre profiles are also contemplated, e.g. an oval,
ellipse, delta, star, multilobal, or other irregular cross
section, as well as splittable fibres. The bicomponent fibres
will typically have a high melting and low melting polyolefin
component which comprise, respectively, polypropyl-
ene/polyethylene (the polyethylene comprising HDPE, LDPE
and/or LLDPE), high density polyethylene/linear low density
polyethylene, polypropylene random copolymer/polyethylene, or
polypropylene/polypropylene random copolymer.
In certain cases, e.g. when the two components of the fibres
comprise high density polyethylene/linear low density poly-
ethylene or polypropylene/polypropylene random copolymer, the
difference in melting points the difference in melting points
between the two polyolefin components may be quite small,
e.g. about 7-8°C and in some cases even as low as about 4-
5°C. However, it is generally preferred that the two
components have melting points which differ by at least about
20°C, preferably at least about 25°C, more preferably at
least about 28°C, e.g, at least about 30°C.
As mentioned above, a presently preferred aspect of the in-
vention relates to a drylaid nonwoven material containing

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6
polyolefin bicomponent fibres in which the low melting poly-
olefin component comprises a non-grafted component and a
grafted component, the grafted component having been grafted
with an unsaturated dicarboxylic acid or an anhydride
thereof. Examples of such acids and anhydrides are malefic
acid, malefic anhydride and derivatives thereof such as citra-
conic acid, citraconic anhydride and pyrocinchonic anhydride;
fumaric acid and derivatives thereof; unsaturated derivatives
of malonic acid such as 3-butene-l,l-dicarboxylic acid,
benzylidene malonic acid and isopropylidene malonic acid; and
unsaturated derivatives of succinic acid such as itaconic
acid and itaconic anhydride.
Malefic acid and malefic anhydride are particularly preferred
as the dicarboxylic acid or anhydride thereof. When these
compounds are grafted onto a polyolefin chain, the resulting
chain is provided with succinic acid or succinic anhydride
groups, respectively, grafted onto it. The grafting of the
dicarboxylic acid or anhydride thereof onto the polyolefin
may be performed in a manner that is known per se, see e.g.
the above-mentioned EP 0465203, US 4,950,541 and US
4, 684, 576.
The weight ratio of grafted polyolefin to non-grafted poly-
olefin in the low melting polyolefin component of the bicom-
ponent fibres will be within the range of about 1:99 to
50:50, typically about 1.5:98.5 to 30:70, more typically
about 2:98 to 20:80, e.g. about 3:97 to 15:85, such as about
5:95 to 10:90.
Within the grafted polyolefin, the content of carboxylic acid
or anhydride thereof is typically in the range of about 1-30
(by weight), typically about 2-20~, more typically about
3-150, such as about 5-10°.
1 1 1

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7
The weight ratio between the high melting and low melting
polyolefin components will be in the range of from 10:90 to
90:10, typically about 20:80 to 80:20, more typically about
30:70 to 70:30, e.g. 35:65 to 65:35.
As mentioned above, drylaid nonwovens according to the inven-
tion comprising polyolefin bicomponent fibres and natural fi-
bres may be characterised by an improved bonding of the bi-
component fibres to the natural fibres as determined by a
standardised dust test whose result reflects the quality of
the bonding between the two types of fibres. In this stan-
dardised test, drylaid nonwoven samples having a base weight
of about 85 g/m~ and a thickness of about 1.1 mm are prepared
using a line speed of 20 or 40 m/min from a mixture of 25~~ by
weight of the synthetic fibres being tested and 75o by weight
of a cellulose pulp fibre (e. g. NB 416 from Weyerhauser).
Nonwovens to be tested are generally prepared using a series
of different bonding temperatures (e. g. using hot air or cal-
ender bonding, typically a hot air oven) in order to optimise
the properties of a given nonwoven.
The determination of the dust value of a nonwoven is per-
formed as follows. Before the measurement is carried out, the
nonwoven samples to be tested are conditioned for at least 12
hours to ensure that all of the samples have been subjected
to the same temperature and humidity conditions. Since, as
described below, the results are often expressed as a rela-
tive value compared to a control, the exact temperature and
relative humidity for the conditioning of the samples is not
critical, as long as all samples to be compared have been
subjected to the same conditions. Ambient temperature and hu-
midity conditions may therefore be used. Prior to condition-
ing, the nonwovens are cut into individual samples with a
size of 12 x 30 cm. After conditioning, a cardboard strip
with a width of 5 mm is attached to the short sides of the
sample, after which the sample with the attached cardboard

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8
strips is weighed on a laboratory scale with an accuracy of
~0.1 mg. The nonwoven sample to be tested is then fixed with
two clamps having a length of 12 cm, each of which is mounted
on an arm. The exposed area of the fixed nonwoven is about
310 cm', which is about the size of a piece of A4 paper. One
of the arms is stationary, while the other arm is rotatable
and is attached to a spring.
The test is performed by rotating the rotatable arm 45°, so
that the nonwoven sample goes from a "stretched out" condi-
tion to a "relaxed" condition, after which the rotatable arm
is released, whereby the action of the spring returns the ro-
tatable arm to its original position. The movement of the arm
is stopped by the nonwoven sample, which thus is subjected to
a small vibration and stretching effect designed to be simi-
lar to the conditions a nonwoven roll is subjected to when it
is unrolled at the converter, the vibration and stretching
resulting in a loss of loose fibres at the fibre surface.
This action is repeated 50 times. The stretching force the
sample is subjected to must of course lie within the non-
woven's elasticity limit, so that the nonwoven is not sub-
stantially deformed or damaged during the test. For the same
reason, and taking into consideration that the tensile
strength of different nonwovens can vary considerably, the
force provided by the spring must obviously be compatible
with the nonwoven to be tested, so that the nonwoven is on
the one hand returned to its original stretched out position
and subjected to a slight vibration and stretching, but is on
the other hand not excessively stretched so as to become de-
formed or damaged.
After having been subjected to the vibration/stretching ac-
tion 50 times, the sample is again weighed, and the differ-
ence between the two values is calculated and expressed as mg
of dust.
1 1 1

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9
In this standardised dust test, the result in mg will often
be no more than about 15 mg, typically no more than about 10
mg, preferably no more than about 5 mg, more preferably no
more than about 4 mg, still more preferably no more than
about 3 mg, most preferably no more than about 2 mg. For non-
wovens with a particularly good affinity between the syn-
thetic fibres and the natural fibres, the result can be as
low as abort 1 mg of dust.
An alternative and often preferred way of defining the dust-
reducing properties of a given fibre in the standardised dust
test is in terms of reduction of the amount of dust (in mg)
in a standard nonwoven prepared from fibres of the invention
compared to a similar nonwoven prepared from similar fibres
without the grafted polyolefin component. In this case, the
nonwoven prepared from the fibres of the invention should
show a dust reduction of at. least about 40o by weight com-
pared to the control nonwoven prepared with the control fi-
bres, typically at least about 50o by weight. Preferably, the
dust reduction is at least about 600, more preferably at
least about 700, and still more preferably at least about
800. For fibres with particularly good cellulose-binding
properties, the dust reduction can be as much as about 90=~ or
more. Since the dust properties of a given nonwoven can vary
greatly depending on factors such as the nature of the bicom-
ponent fibres and the nature of the cellulose or other fibres
as well as e.g. the particular webforming and bonding proc-
ess, it will often be preferred to compare the performance of
a given fibre in terms of i.ts dust reduction percentage com-
pared to a similar control fibre rather than in terms of an
absolute value in mg.
It is furthermore contemplated that the fibres of the inven-
tion will also show an improved bonding and fixation of not
only cellulosic fibres but also different superabsorbent
polymers (SAP) that are commonly used in hygiene absorbent

CA 02281802 1999-08-24
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products in the form of particles or fibres. Such SAPS, e.g.
a crosslinked polyacrylic acid salt, are typically used in
the form of superabsorbent particles in the absorbent core of
e.g. disposable diapers, since they are able to absorb many
5 times their weight in liquid and form a gel that holds onto
the liquid upon wetting. Even if the fibres of the invention
are not directly bonded to the SAP particles, it is contem-
plated that the improved bonding of the fibres of the inven-
tion to the cellulosic fibres will result in an improved
10 structure that in itself serves to ensure that the SAP parti-
cles are maintained in the desired location in the absorbent
product, whereby the function of the SAP will be improved.
The spinning of the fibres is preferably accomplished using
conventional melt spinning (also known as "long spinning"),
with spinning and stretching being performed in two separate
steps. Alternatively, other means of manufacturing staple fi-
bres, in particular "compact spinning", which is a one step
operation, may be used to carry out the invention. Methods
for the spinning of bicomponent fibres and filaments are
well-known in the art. Such methods generally involve extru-
sion of the melts to produce filaments, cooling and drawing
of the filaments, treatment of the filaments with an appro-
priate spin finish to result in desired surface properties,
e.g. using a spin finish to provide hydrophilic properties
when the fibres are to be used in an absorbent core and/or to
provide antistatic properties, stretching the filaments,
typically, treating with a second spin finish, texturizing
the filaments, drying the filaments and cutting the filaments
to result in staple fibres.
As indicated above, the drylaid nonwovens of the present in-
vention typically comprise, in addition to the polyolefin bi-
component fibres, at least one additional fibrous material,
in particular natural fibres or regenerated fibres, e.g.
selected from cellulose fibres, viscose rayon fibres and
T

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11
Lyocell fibre ~. The cellulose fibres may e.g. be pulp fibres
or cotton fib res and are in particular pulp fibres such as
CTMP (chemi-thermo-mechanical pulp), sulfite pulp or kraft
pulp.
The fibrous web comprising the bicomponent fibres and the ad-
ditional fibrous material will typically comprise 5-50$ by
weight of the bicomponent fibres and 50-95$ by weight of the
additional fibrous material, more typically 10-40$ by weight
of the bicomponent fibres and 60-90$ by weight of the addi-
tional fibrous material, e.g. 15-25~ by weight of the bicom-
ponent fibres and 75-85$ by weight of the additional fibrous
material.
EXAMPLES
EXAMPLE 1
Trials were run with different polyolefin bicomponent fibres
to evaluate their bondability to cellulose pulp fibres.
The cellulose fibres were NB 416 from Weyerhauser. The weight
ratio of between the bicomponent fibres and the'cellulose fi-
bres was 25:75.
The tested bicomponent fibres had the following composition,
fibre No..l being according to the present invention:
l: Core: polypropylene; sheath: loo grafted LLDPE (5$ malefic
acid grafted onto 95$ LLDPE), 90$ LLDPE.
Z. Control fibre; core: polypropylene; sheath: 100$ LLDPE.
3. AL-Speci ~ -C from Danaklon A/S; polypropylene core, HDPE
sheath. ~
4. Hercules 449 from Hercules Inc., length 5 mm, fineness 1.5
dtex; polypropylene core/polyethylene sheath.
~ Tr~dem~

CA 02281802 2004-04-29
WO 98/45519 PCT/DK98/00131
12
Bicomponent fibres 1, 2 and 3 all had a fineness of 1.7 dtex,
a length of 6 mm and a weight ratio between core and sheath
of 35:65.
The fibres were run at a very low speed of 8.33 m/min on an
airlaid apparatus (Dan-Web, Denmark), since the primary pur-
pose of these trials was to determine the fibres' ability to
bond to cellulose. During the trials, an airlaid nonwoven
product having a basis weight of 80 g/m2 was aimed at, and
the trials were started at the lowest possible bonding tem-
perature, after which the temperature in the oven was in-
creased in increments of 5 or 10°C.
Results:
The cross direction (CD) dry strength, machine direction (MD)
dry strength and MD wet strength were determined an samples
produced at different temperatures as indicated below (EDANA
test method No. 20.2-89, tested at a speed of 100 mm/min).
Furthermore, the thickness and the basis weight (g/m2) of
each sample was determined, and this information (not listed
below) was used to adjust the strength values to result in
normalised values that are comparable in spite of minor
differences in thickness and base weight of the individual
samples tested. The results are shown below.
Tm~t~

CA 02281802 1999-08-24
WO 98/45519 PCT/DK98/00131
13
BondingStrength Strength Strength
MD MD,
SampleTemp. CD wet
No. ~C N/5cm N/5cm N/5cm
1 125 25.9 25.2 25.4
1 130 20.9 20.5 18.3
1 135 23.5 22.4 20.6
1 140 23.1 22.3 20.1
1 145 23.9 22.5 18.0
2 125 17.46 15.43 15.13
2 130 13.63 13.32 11.62
2 135 15.17 15.06 12.66
2 140 16.25 15.72 13.99
2 145 12.77 7.3.08 9.78
2 150 11.28 7Ø77 6.77
2 155 4.15 4.26 2.23
3 130 24.01 23.37 23.59
3 140 19.34 7.8.08 18.57
3 150 15.59 1.6.66 14.92
4 130 7.98 7.78 7.98
4 140 9.23 7.93 8.73
4 150 8.83 8.93 8.83
4 160 4.21 4.31 2.26
4 170 3.24 3.14 1.27
The results of the dust test were as follows (average of 2
trials, except for fibre No. 3, which is the range of results
obtained in a larger number of test runs with this fibre):
Fibre number Dust (mg)
1 1.7
2 7.4
3 12-30
4 14.0
Compared to the control PP/PE fibres 2, 3 and 4, fibre 1 ac-
cording to the invention gave a significantly improved result
in the dust test, the greatly reduced dust generation re-
flecting a significantly improved bonding of the bicomponent
fibres of the invention to the cellulose fluff pulp fibres.
Observation of the samples by microscope also revealed bond-
ing of the bicomponent fibres of the invention to the cellu-

CA 02281802 19'99-08-24
WO 98/45519 PCT/DK98/00131
14
lose fibres. It was also found that fibre 1 gave a bulkier
nonwoven compared to fibres 2 and 3 (fibre 4 was not compared
in this regard). Furthermore, as shown by the strength values
given in the table above, the fibres of the invention re-
suited in nonwovens with improved strength and elongation
characteristics.
EXAMPLE 2
A test of the ability of two different fibres to bind cellu-
lose was performed in a test on a commercial airlaid line.
Airlaid nonwovens with a basis weight of about 80 g/m- and a
thickness of about 1 mm were produced. The nonwovens con-
tained 25o by weight of bicomponent fibres and 75o by weight
of cellulose pulp fibres. The bicomponent fibres tested had a
fineness of 1.7 dtex and a length of 6 mm. In addition to
(control) fibre No. 3 described above, a bicomponent fibre
(referred to as No. 5) with the same cellulose-binding addi-
tive as in fibre No. 1 but a higher melting polyethylene
sheath component (HDPE) was tested. This fibre thus had the
following composition:
5: Core: polypropylene; sheath: 10o grafted LLDPE (5o malefic
acid grafted onto 95o LLDPE), 90o HDPE.
The individual nonwoven samples were bonded at different tem-
peratures with intervals of 3°C in order to ascertain the op-
timum bonding temperature for the individual fibres.
It was found that the nonwovens containing bicomponent fibres
of the invention (fibre 5) resulted in an improved binding of
the cellulose fibres as evidenced by a reduced generation of
dust during processing compared to the control fi-
bre(quantitative measurements were not performed in this
case). Furthermore, the fibres of the invention resulted in
...._.. . T

CA 02281802 1999-08-24
10
WO 98/45519 PCT/DK98/00131
nonwovens with improved strength characteristics as evidenced
by the following test results:
MD tensile strength, dry (N/5 cm)
Bonding Fibre
Temp. °C Control 5
137 13.96 15.08
140 15.77 19.01
143 ~ 12.56 19.40
146 - 15.41
EXAMPLE 3
Tests were performed to illustrate the influence of varying
the amount of additive (malefic acid grafted LLDPE with an ac-
15 tine content of 50) in the sheath component.
The bicomponent fibres tested all had a fineness of 1.7 dtex
and a length of 6 mm. The core/sheath weight ratio for fibres
6-9 was 35:65, and 50:50 for fibre No. 10. The core was in
all cases of polypropylene. Nonwovens were produced on a com-
mercial airlaid line using technology from Dan-Web, Denmark,
the nonwovens having a basis weight of about 80 g/m', a
thickness of about 1 mm, and weight ratio of bicomponent
fibres to cellulose fibres of 25:75. Samples with each of the
bicomponent fibres were tested at 3 different bonding
temperatures, 137, 140 and 143°C.
The sheath composition of the individual fibres was as fol-
lows:
6: 5o grafted LLDPE (5o malefic acid grafted onto 95o LLDPE),
95o LLDPE.
7: 5o grafted LLDPE (5o malefic acid grafted onto 95o LLDPE),
95 o HDPE .
8: 10o grafted LLDPE (5° malefic acid grafted onto 95o LLDPE),
9 0 ° HDPE .

CA 02281802 1999-08-24
WO 98/45519 PCT/DK98/00131
16
9: 12.50 grafted LLDPE (5% malefic acid grafted onto 950
LLDPE), 87.50 HDPE.
10. 13° grafted LLDPE (5o malefic acid grafted onto 950
LLDPE ) , 8 7 o HDPE .
As a control, AL-Special-C from Danaklon A/S (polypropylene
core, HDPE sheath; No. 3 above), was used.
The wet and dry tensile strength and the elongation of the
various nonwovens was tested. As the results below show, the
nonwovens containing the fibres of the invention showed a
substantially improved dry and wet tensile strength compared
to the control nonwovens. In addition, some of the fibres of
the invention, notably Nos. 6, 7 and 8, showed elongation
values above those of the control fibres, while fibre 10 and
to a certain extent fibre 9 showed elongation values lower
than for the control fibres. The suboptimal results for fi-
bres 9 and 10 in terms of elongation are believed to be re-
lated to the fact that some difficulties were experienced in
spinning these fibres with a relatively large amount of the
grafted component in the sheath. It is believed that with
further tests and optimisation of the spinning process and
other process parameters, it will be possible to obtain im-
proved results for these and other fibres with a relatively
large content of the grafted polyolefin component as well.
Tensile
strength,
dry (N/5
cm)
Bonding Fibre
No.
Temp . Control 6 7 8 9 10
C
137 8.54 21.58 17.65 16.91 18.68 12.75
140 9.85 18.58 20.98 17.00 17.95 14.40
143 8.53 18.59 19.25 30.63 18.18 16.38
_....__.........T...

CA 02281802 1999-08-24
WO 98/45519 PCT/DK98/00131
17
Elongation,
dry (o)
Bonding Fibre No.
Temp . Control 6 7 8 9 10
C
137 185.25 190.25 154.50 199.67 174.25 133.50
140 175.00 184.75 188.25 195.67 169.00 119.00
143 178.67 189.25 185.78 184.25 185.75 144.75
Tensile
strength,
wet (N/5
cm)
Bonding Fibre
No.
Temp . Control 6 7 8 9 10
C
137 8.24 17.57 15.21 16.03 17.11 9.39
140 9.32 13.64 17 - 13.78 16.31 10.19
143 8.01 15.34 15.2 24.08 17.04 16.31
E1 ion,
wet (o)
Bonding Fibre
No.
Temp . Control 6 7 8 9 10
C
137 175.25 220.75 161.50 179.67 205.25 118.75
140 159.50 194.25 177.75 186.75 189.00 132.50
143 142.50 196.00 179.67 177.00 188.50 123.75
A visual assessment of the dust properties of the nonwovens
indicated that all of the tested bicomponent fibres of the
invention had an improved bonding to the cellulose fibres
compared to the control bicomponent fibres. Fibres 7 and 8
ran particularly well on the production line, and, as the re-
sults above show, excellent strength values were also
obtained for nonwovens containing these fibres.
The results of the fibres of this example in the dust test
were as follows (fibre 10 was not tested):

CA 02281802 19,99-08-24
WO 98/45519 PCT/DK98/00131
18
Fibre number Dust (mg)
6 6.6
7 14.9
8 5.8
9 6.7
Control 29.9
It can be concluded from the above that good results were ob-
tained with all levels of additive addition, although there
appeared to be a tendency for better results with additions
of about 5-100.

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Administrative Status

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Event History

Description Date
Time Limit for Reversal Expired 2015-03-31
Letter Sent 2014-03-31
Inactive: IPC deactivated 2013-11-12
Inactive: IPC deactivated 2013-11-12
Inactive: IPC assigned 2013-03-28
Inactive: First IPC assigned 2013-03-28
Inactive: IPC expired 2012-01-01
Inactive: IPC expired 2012-01-01
Inactive: IPC from MCD 2006-03-12
Grant by Issuance 2005-05-24
Inactive: Cover page published 2005-05-23
Pre-grant 2005-03-14
Inactive: Final fee received 2005-03-14
Notice of Allowance is Issued 2004-09-28
Letter Sent 2004-09-28
Notice of Allowance is Issued 2004-09-28
Inactive: Approved for allowance (AFA) 2004-09-20
Amendment Received - Voluntary Amendment 2004-04-29
Inactive: S.30(2) Rules - Examiner requisition 2003-10-29
Amendment Received - Voluntary Amendment 2002-02-06
Letter Sent 2001-10-02
Amendment Received - Voluntary Amendment 2001-08-27
Request for Examination Requirements Determined Compliant 2001-08-27
All Requirements for Examination Determined Compliant 2001-08-27
Request for Examination Received 2001-08-27
Letter Sent 1999-11-22
Inactive: Cover page published 1999-10-27
Inactive: Single transfer 1999-10-22
Inactive: IPC assigned 1999-10-21
Inactive: First IPC assigned 1999-10-21
Inactive: Courtesy letter - Evidence 1999-10-05
Inactive: Notice - National entry - No RFE 1999-09-29
Application Received - PCT 1999-09-27
Application Published (Open to Public Inspection) 1998-10-15

Abandonment History

There is no abandonment history.

Maintenance Fee

The last payment was received on 2005-03-03

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  • the reinstatement fee;
  • the late payment fee; or
  • additional fee to reverse deemed expiry.

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Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
FIBERVISIONS A/S
Past Owners on Record
ANNE MONRAD LARSEN
PIA HOLM HANSEN
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Claims 2001-08-27 5 171
Abstract 1999-08-24 1 52
Cover Page 1999-10-27 1 44
Description 1999-08-24 18 773
Claims 1999-08-24 5 186
Description 2004-04-29 18 773
Claims 2004-04-29 5 172
Cover Page 2005-04-21 1 34
Notice of National Entry 1999-09-29 1 208
Courtesy - Certificate of registration (related document(s)) 1999-11-22 1 115
Acknowledgement of Request for Examination 2001-10-02 1 194
Commissioner's Notice - Application Found Allowable 2004-09-28 1 160
Maintenance Fee Notice 2014-05-12 1 170
Correspondence 1999-09-29 1 14
PCT 1999-08-24 14 519
Fees 2002-04-02 1 31
Correspondence 2005-03-14 1 26