(19) |
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(11) |
EP 0 973 966 B1 |
(12) |
EUROPEAN PATENT SPECIFICATION |
(45) |
Mention of the grant of the patent: |
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18.09.2002 Bulletin 2002/38 |
(22) |
Date of filing: 31.03.1998 |
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(86) |
International application number: |
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PCT/DK9800/131 |
(87) |
International publication number: |
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WO 9804/5519 (15.10.1998 Gazette 1998/41) |
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(54) |
CELLULOSE-BINDING FIBRES
CELLULOSE BINDENDE FASERN
FIBRES SE LIANT A LA CELLULOSE
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(84) |
Designated Contracting States: |
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CH DE DK ES FI FR GB IT LI SE |
(30) |
Priority: |
08.04.1997 DK 39497
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(43) |
Date of publication of application: |
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26.01.2000 Bulletin 2000/04 |
(73) |
Proprietor: FIBERVISIONS A/S |
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6800 Varde (DK) |
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(72) |
Inventors: |
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- HANSEN, Pia, Holm
DK-6862 Tistrup (DK)
- LARSEN, Anne, Monrad
DK-6700 Esbjerg (DK)
|
(74) |
Representative: Plougmann, Vingtoft & Partners A/S |
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Sankt Annae Plads 11,
P.O. Box 3007 1021 Copenhagen K 1021 Copenhagen K (DK) |
(56) |
References cited: :
EP-A- 0 019 950 DE-A- 19 506 083
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EP-A- 0 465 203 US-A- 4 950 541
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|
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- DATABASE WPI Section Ch, Week 7916 Derwent Publications Ltd., London, GB; Class A17,
AN 79-30238B XP002057459 & JP 54 030 929 A (CHISSO CORP) , 7 March 1979 & CHEMICAL
ABSTRACTS, vol. 91, no. 4, 23 July 1979 Columbus, Ohio, US; abstract no. 22388p, KUNIMUNE
K ET AL: "Synthetic nonwoven fabrics" page 91; column 2;
- DATABASE WPI Section Ch, Week 9023 Derwent Publications Ltd., London, GB; Class A96,
AN 90-174051 XP002057460 & JP 02 112 415 A (UNITIKA LTD) , 25 April 1990
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
|
FIELD OF THE INVENTION
[0001] 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
[0002] Hygienic absorbent products such as disposable diapers contain, 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 fibres such
as cellulose fluff pulp fibres, synthetic fibres based on e.g. polyolefin and/or polyester
and a superabsorbent 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 fibres and the
SAP are locked into place within the structure.
[0003] 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 fibres. 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
necessarily) considerably longer. As a result, dust problems are created in the manufacturing
process, and the performance of the resulting nonwovens is also suboptimal, since
a large proportion of the natural fibres is not bonded to any of the synthetic fibres
or otherwise held in place by means of the structure formed by bonding of the synthetic
fibres.
[0004] 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 fibres and which therefore is particularly suitable for the production
of drylaid nonwovens comprising a mixture of synthetic fibres and natural fibres.
[0005] EP 0465203-B1 discloses thermally bonded fibrous wet laid webs containing bicomponent
fibres comprising a first component 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 polyethylene (HDPE) with a density of 0.94-0.965 g/cc
which has been grafted with maleic acid or maleic anhydride to provide succinic acid
or succinic anhydride groups along the HDPE polymer.
[0006] EP 0421734-B1 discloses thermobondable bicomponent fibres composed of two different
polyolefins having melting points which differ by at least 20°C, the lower melting
polyolefin containing 3-10% 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.
[0007] US 4,950,541 discloses succinic acid and succinic anhydride grafts of linear ethylene
polymers obtained by grafting maleic acid or maleic 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.
[0008] EP 0465203-A discloses wetlaid bonded fibrous webs comprising bicomponent fibres
including a first component of polyester or polyamide and a second component of linear
low density polyethylene. The second component may also include a grafted high density
polyethylene.
[0009] US 4/684,576 discloses the production of blends of grafted HDPE with ungrafted LLDPE
or LDPE, the HDPE having been grafted with maleic acid or maleic anhydride to provide
succinic acid or succinic anhydride groups along the HDPE polymer. The blends are
disclosed for use in producing laminate structures.
[0010] It has now unexpectedly been found that polyolefin bicomponent fibres whose low melting
component comprises a non-grafted polyolefin component and a grafted polyolefin component
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 improved strength properties
in the resulting nonwovens.
BRIEF DISCLOSURE OF THE INVENTION
[0011] In one aspect, the present invention relates to a drylaid nonwoven material comprising
bicomponent fibres and at least one additional fibrous material, the 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 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 component has been grafted with an unsaturated dicarboxylic acid
or an anhydride thereof.
[0012] Another aspect of the invention relates to a method for producing a drylaid nonwoven
material, comprising forming a fibrous web using dry lay nonwoven equipment, the web
comprising bicomponent fibres and at least one additional fibrous material, the 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 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 component has been grafted with an unsaturated dicarboxylic
acid or an anhydride thereof, and bonding the fibrous web to result in the drylaid
nonwoven material.
[0013] A further aspect of the invention relates to a bicomponent fibre as described above
for the production of drylaid nonwoven materials.
DETAILED DISCLOSURE OF THE INVENTION
[0014] The term "polyolefin component" for the purpose of this invention means a polyolefin-containing
polymeric material of which the largest part (by weight) consists of homo- or copolymers
of monoolefins such as ethylene, propylene, 1-butene, 4-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 whiteners and colourants such as TiO
2, etc.
[0015] Although the present description will for the sake of simplicity generally refer
to "fibres", i.e. cut staple fibres, it is to be understood that the present invention
will also be applicable to the production of continuous polyolefin filaments, e.g.
spunbonded filaments.
[0016] The term "drylaid" nonwoven refers to a nonwoven material produced by a dry process,
including airlaid nonwovens, carded nonwovens, etc.
[0017] 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 which 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, polypropylene/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.
[0018] In certain cases, e.g. when the two components of the fibres comprise high density
polyethylene/linear low density polyethylene 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.
[0019] As mentioned above, a presently preferred aspect of the invention relates to a drylaid
nonwoven material containing polyolefin bicomponent fibres in which the low melting
polyolefin 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 maleic acid, maleic anhydride
and derivatives thereof such as citraconic acid, citraconic anhydride and pyrocinchonic
anhydride; fumaric acid and derivatives thereof; unsaturated derivatives of malonic
acid such as 3-butene-1,1-dicarboxylic acid, benzylidene malonic acid and isopropylidene
malonic acid; and unsaturated derivatives of succinic acid such as itaconic acid and
itaconic anhydride.
[0020] Maleic acid and maleic 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.
[0021] The weight ratio of grafted polyolefin to non-grafted polyolefin in the low melting
polyolefin component of the bicomponent 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.
[0022] 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 3-15%, such as about 5-10%.
[0023] 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.
[0024] As mentioned above, drylaid nonwovens according to the invention comprising polyolefin
bicomponent fibres and natural fibres may be characterised by an improved bonding
of the bicomponent 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 standardised test, drylaid nonwoven samples having a base weight of about
85 g/m
2 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 75% 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 calender bonding, typically a hot air oven) in order to optimise the properties
of a given nonwoven.
[0025] The determination of the dust value of a nonwoven is performed by Test Method A:
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 relative 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 humidity conditions may therefore be used. Prior to conditioning, 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 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
2, 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.
[0026] The test is performed by rotating the rotatable arm 45°, so that the nonwoven sample
goes from a "stretched out" condition to a "relaxed" condition, after which the rotatable
arm is released, whereby the action of the spring returns the rotatable 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 similar
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 substantially 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 deformed or damaged.
[0027] After having been subjected to the vibration/stretching action 50 times, the sample
is again weighed, and the difference between the two values is calculated and expressed
as mg of dust.
[0028] 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 nonwovens with a particularly good affinity
between the synthetic fibres and the natural fibres, the result can be as low as about
1 mg of dust.
[0029] 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 40% by weight compared to the control nonwoven
prepared with the control fibres, typically at least about 50% by weight. Preferably,
the dust reduction is at least about 60%, more preferably at least about 70%, and
still more preferably at least about 80%. 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 bicomponent fibres and the nature of the cellulose or other fibres as well
as e.g. the particular webforming and bonding process, it will often be preferred
to compare the performance of a given fibre in terms of its dust reduction percentage
compared to a similar control fibre rather than in terms of an absolute value in mg.
[0030] It is furthermore contemplated that the fibres of the invention 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 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 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 contemplated that the improved
bonding of the fibres of the invention to the cellulosic fibres will result in an
improved structure that in itself serves to ensure that the SAP particles are maintained
in the desired location in the absorbent product, whereby the function of the SAP
will be improved.
[0031] 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 fibres, 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 extrusion of the melts to produce filaments, cooling
and drawing of the filaments, treatment of the filaments with an appropriate 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.
[0032] As indicated above, the drylaid nonwovens of the present invention typically comprise,
in addition to the polyolefin bicomponent fibres, at least one additional fibrous
material, in particular natural fibres or regenerated fibres, e.g. selected from cellulose
fibres, viscose rayon fibres and Lyocell fibres. The cellulose fibres may e.g. be
pulp fibres or cotton fibres and are in particular pulp fibres such as CTMP (chemi-thermo-mechanical
pulp), sulfite pulp or kraft pulp.
[0033] The fibrous web comprising the bicomponent fibres and the additional 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 additional fibrous material, e.g. 15-25% by weight
of the bicomponent fibres and 75-85% by weight of the additional fibrous material.
EXAMPLES
EXAMPLE 1
[0034] Trials were run with different polyolefin bicomponent fibres to evaluate their bondability
to cellulose pulp fibres.
[0035] The cellulose fibres were NB 416 from Weyerhauser. The weight ratio of between the
bicomponent fibres and the cellulose fibres was 25:75.
[0036] The tested bicomponent fibres had the following composition, fibre No. 1 being according
to the present invention:
1: Core: polypropylene; sheath: 10% grafted LLDPE (5% maleic acid grafted onto 95%
LLDPE), 90% LLDPE.
2. Control fibre; core: polypropylene; sheath: 100% LLDPE.
3. AL-Special-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.
[0037] 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.
[0038] The fibres were run at a very low speed of 8.33 m/min on an airlaid apparatus (Dan-Web,
Denmark), since the primary purpose 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/m
2 was aimed at, and the trials were started at the lowest possible bonding temperature,
after which the temperature in the oven was increased in increments of 5 or 10°C.
Results:
[0039] The cross direction (CD) dry strength, machine direction (MD) dry strength and MD
wet strength were determined on 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/m
2) 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.
Sample No. |
Bonding Temp. °C |
Strength MD N/5cm |
Strength CD N/5cm |
Strength MD, wet 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 |
13.49 |
2 |
145 |
12.77 |
13.08 |
9.78 |
2 |
150 |
11.28 |
10.77 |
6.77 |
2 |
155 |
4.15 |
4.26 |
2.23 |
|
3 |
130 |
24.01 |
23.37 |
23.59 |
3 |
140 |
19.34 |
18.08 |
18.57 |
3 |
150 |
15.59 |
16.66 |
14.42 |
|
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 |
[0040] 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 |
[0041] Compared to the control PP/PE fibres 2, 3 and 4, fibre 1 according to the invention
gave a significantly improved result in the dust test, the greatly reduced dust generation
reflecting 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 bonding of the bicomponent fibres of the invention to the cellulose 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 resulted in nonwovens with improved
strength and elongation characteristics.
EXAMPLE 2
[0042] A test of the ability of two different fibres to bind cellulose was performed in
a test on a commercial airlaid line. Airlaid nonwovens with a basis weight of about
80 g/m
2 and a thickness of about 1 mm were produced. The nonwovens contained 25% by weight
of bicomponent fibres and 75% 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 additive 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: 10% grafted LLDPE (5% maleic acid grafted onto 95%
LLDPE), 90% HDPE.
[0043] The individual nonwoven samples were bonded at different temperatures with intervals
of 3°C in order to ascertain the optimum bonding temperature for the individual fibres.
[0044] 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 fibre(quantitative measurements
were not performed in this case). Furthermore, the fibres of the invention resulted
in nonwovens with improved strength characteristics as evidenced by the following
test results:
MD tensile strength, dry (N/5 cm) |
Bonding Temp. °C |
Fibre |
|
Control |
5 |
137 |
13.96 |
15.08 |
140 |
15.77 |
19.01 |
143 |
12.56 |
19.40 |
146 |
- |
15.41 |
EXAMPLE 3
[0045] Tests were performed to illustrate the influence of varying the amount of additive
(maleic acid grafted LLDPE with an active content of 5%) in the sheath component.
[0046] 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 commercial
airlaid line using technology from Dan-Web, Denmark, the nonwovens having a basis
weight of about 80 g/m
2, 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.
[0047] The sheath composition of the individual fibres was as follows:
6: 5% grafted LLDPE (5% maleic acid grafted onto 95% LLDPE), 95% LLDPE.
7: 5% grafted LLDPE (5% maleic acid grafted onto 95% LLDPE), 95% HDPE.
8: 10% grafted LLDPE (5% maleic acid grafted onto 95% LLDPE), 90% HDPE.
9: 12.5% grafted LLDPE (5% maleic acid grafted onto 95% LLDPE), 87.5% HDPE.
10. 13% grafted LLDPE (5% maleic acid grafted onto 95% LLDPE), 87% HDPE.
[0048] As a control, AL-Special-C from Danaklon A/S (polypropylene core, HDPE sheath; No.
3 above), was used.
[0049] 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 fibres 9 and 10 in terms of elongation are believed to
be related 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 improved 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
Temp.°C |
Control |
Fibre No. |
|
|
6 |
7 |
8 |
9 |
10 |
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 |
Elongation, dry (%) |
Bonding
Temp.°C |
Control |
Fibre No. |
|
|
6 |
7 |
8 |
9 |
10 |
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
Temp.°C |
Control |
Fibre No. |
|
|
6 |
7 |
8 |
9 |
10 |
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 |
Elongation, wet (%) |
Bonding
Temp.°C |
Control |
Fibre No. |
|
|
6 |
7 |
8 |
9 |
10 |
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 |
[0050] 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 results above show, excellent strength values
were also obtained for nonwovens containing these fibres.
[0051] The results of the fibres of this example in the dust test were as follows (fibre
10 was not tested):
Fibre number |
Dust (mg) |
6 |
6.6 |
7 |
14.9 |
8 |
5.8 |
9 |
6.7 |
Control |
29.9 |
[0052] It can be concluded from the above that good results were obtained with all levels
of additive addition, although there appeared to be a tendency for better results
with additions of about 5-10%.
1. A drylaid nonwoven material comprising bicomponent fibres and at least one additional
fibrous material, said 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 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 component has been
grafted with an unsaturated dicarboxylic acid or an anhydride thereof,
wherein the at least one additional fibrous material is selected from natural or regenerated
fibrous material,
wherein 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 is such that the weight ratio of grafted polyolefin to non-grafted polyolefin
is in the range of 1:99 to 50:50;
and wherein 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 Method A of not more than about 10 mg.
2. A material according to claim 1, wherein 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 is such that the weight ratio of grafted
polyolefin to non-grafted polyolefin is in the range of 1.5:98.5 to 30:70, such as
2:98 to 20: 80, 3:97 to 15:85; most preferably in the range of 5:95 to 10:90.
3. A material according to any one of claims 1-2, wherein the natural fibres and regenerated
fibres are selected from the group consisting of cellulose fibre, viscose fibre and
Lyocell fibres.
4. A drylaid nonwoven material according to claim 3, wherein the additional fibrous material
comprises cellulose fluff pulp fibres.
5. A drylaid nonwoven material according to any of claims 1-4, wherein the nonwoven material
shows a dust value in the standardised dust test Method A of not more than about 5
mg, more preferably not more than about 4 mg, still more preferably no more than about
3 mg, most preferably no more than about 2 mg.
6. A drylaid nonwoven material according to any one of claims 1-5, wherein the grafted
polyolefin component of the bicomponent fibres has been grafted with a compound selected
from: maleic acid, maleic anhydride and derivatives thereof such as citraconic acid,
citraconic anhydride and pyrocinchonic anhydride; fumaric acid and derivatives thereof;
unsaturated derivatives of malonic acid such as 3-butene-1,1-dicarboxylic acid, benzylidene
malonic acid and isopropylidene malonic acid; and unsaturated derivatives of succinic
acid such as itaconic acid and itaconic anhydride.
7. A drylaid nonwoven material according to claim 6, wherein the grafted polyolefin component
of the bicomponent fibres has been grafted with maleic acid or maleic anhydride.
8. A drylaid nonwoven material according to any one of claims 1-7, 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.
9. A drylaid nonwoven material according to any of the preceding claims 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 any of the preceding claims 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 any of claims 1-10, 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 drylaid nonwoven material according to any of the preceding claims wherein the fibrous
web comprises 5-50% by weight of the bicomponent fibres and 50-95% by weight of additional
fibrous material, typically 10-40% by weight of the bicomponent fibres and 60-90%
by weight of the additional fibrous material, e.g. 15-25% by weight of the bicomponent
fibres and 75-85% by weight of the additional fibrous material.
13. A method for producing a drylaid nonwoven material, comprising forming a fibrous web
using dry lay nonwoven equipment, the web comprising bicomponent fibres and at least
one additional fibrous material, said 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 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 component
has been grafted with an unsaturated dicarboxylic acid or an anhydride thereof, and
bonding the fibrous web to result in the drylaid nonwoven material.
14. A method according to claim 13, wherein the additional fibrous material is selected
from natural fibres and regenerated fibres, e.g. selected from cellulose fibres, viscose
fibres and Lyocell fibres.
15. A method according to claim 14, wherein the additional fibrous material comprises
cellulose fluff pulp fibres.
16. A method according to any one of claims 13-15, wherein the grafted polyolefin component
of the bicomponent fibres has been grafted with a compound selected from: maleic acid,
maleic anhydride and derivatives thereof such as citraconic acid, citraconic anhydride
and pyrocinchonic anhydride; fumaric acid and derivatives thereof; unsaturated derivatives
of malonic acid such as 3-butene-1,1-dicarboxylic acid, benzylidene malonic acid and
isopropylidene malonic acid; and unsaturated derivatives of succinic acid such as
itaconic acid and itaconic anhydride.
17. A method according to claim 16, wherein the grafted polyolefin component of the bicomponent
fibres has been grafted with maleic acid or maleic anhydride.
18. A method according to any one of claims 13-17, 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.
19. A method according to any one of claims 13-18, 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.
20. A method according to any of claims 13-19, 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.
21. A method according to any of claims 13-20, 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.
22. A method according to any of claims 13-21, wherein the fibrous web comprises 5-50%
by weight of the bicomponent fibres and 50-95% by weight of additional fibrous material,
typically 10-40% by weight of the bicomponent fibres and 60-90% by weight of the additional
fibrous material, e.g. 15-25% by weight of the bicomponent fibres and 75-85% by weight
of the additional fibrous material.
23. A bicomponent fibre for the production of drylaid nonwoven materials, the fibre comprising
a low melting polyolefin component and a high melting polyolefin 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 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,
wherein 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 is such that the weight ratio of grafted polyolefin to non-grafted polyolefin
is in the range of 1:99 to 50:50.
1. Trockengelegtes Vliesmaterial, das Zweikomponentenfasern und mindestens ein zusätzliches
Fasermaterial umfasst, wobei die Zweikomponentenfasern eine niedrigschmelzende Polyolefinkomponente
und eine hochschmelzende Polyolefinkomponente umfassen, wobei die niedrigschmelzende
Polyolefinkomponente einen mindestens 4°C niedrigeren Schmelzpunkt als den Schmelzpunkt
der hochschmelzenden Polyolefinkomponente aufweist, die niedrigschmelzende Polyolefinkomponente
mindestens einen Teil der Faseroberfläche ausmacht und eine nichtgepfropfte Polyolefinkomponente
und eine gepfropfte Polyolefinkomponente umfasst, wobei die gepfropfte Polyolefinkomponente
mit einer ungesättigten Dicarbonsäure oder einem Anhydrid davon gepfropft worden ist,
wobei das mindestens eine zusätzliche Fasermaterial aus natürlichem oder regeneriertem
Fasermaterial ausgewählt ist, wobei die niedrigschmelzende Polyolefinkomponente, die
mindestens einen Teil der Faseroberfläche ausmacht und die eine nichtgepfropfte Polyolefinkomponente
und eine gepfropfte Polyolefinkomponente umfasst, so ausgestaltet ist, dass das Gewichtsverhältnis
von gepfropftem Polyolefin zu nichtgepfropftem Polyolefin im Bereich von 1:99 bis
50:50 liegt; und wobei die Zweikomponentenfasern eine Bindungsaffinität zu den natürlichen
oder regenierten Fasern aufweisen, so dass das Vliesmaterial im standardisierten Staub-Testverfahren
A einen Staubwert von nicht mehr als etwa 10 mg aufweist.
2. Material nach Anspruch 1, wobei die niedrigschmelzende Polyolefinkomponente, die mindestens
einen Teil der Faseroberfläche ausmacht und die eine nichtgepfropfte Polyolefinkomponente
und eine gepfropfte Polyolefinkomponente umfasst, so ausgestaltet ist, dass das Gewichtsverhältnis
von gepfropftem Polyolefin zu nichtgepfropftem Polyolefin im Bereich von 1,5:98,5
bis 30:70, wie 2:98 bis 20:80, 3:97 bis 15:85, am stärksten bevorzugt im Bereich von
5:95 bis 10:90 liegt.
3. Material nach einem der Ansprüche 1 - 2, wobei die natürlichen Fasern und regenerierten
Fasern aus Cellulosefasern, Viscosefasem und Lyocellfasern ausgewählt sind.
4. Trockengelegtes Vliesmaterial nach Anspruch 3, wobei das zusätzliche Fasermaterial
Celluloseschliffzellstofffasern ("cellulose fluff pulp fibres") umfasst.
5. Trockengelegtes Vliesmaterial nach einem der Ansprüche 1 - 4, wobei das Vliesmaterial
im standardisierten Staub-Testverfahren A einen Staubwert von nicht mehr als etwa
5 mg, stärker bevorzugt nicht mehr als etwa 4 mg, noch stärker bevorzugt nicht mehr
als etwa 3 mg, am stärksten bevorzugt nicht mehr als etwa 2 mg aufweist.
6. Trockengelegtes Vliesmaterial nach einem der Ansprüche 1 - 5, wobei die gepfropfte
Polyolefinkomponente der Zweikomponentenfasern mit einer Verbindung gepfropft worden
ist, die aus Maleinsäure, Maleinsäureanhydrid und Derivaten davon, wie Citraconsäure,
Citraconsäureanhydrid und Pyrocinchonsäureanhydrid; Fumarsäure und Derivaten davon;
ungesättigten Derivaten der Malonsäure, wie 3-Buten-1,1-dicarbonsäure, Benzylidenmalonsäure
und Isopropylidenmalonsäure; und ungesättigten Derivaten der Bernsteinsäure, wie Itaconsäure
und Itaconsäureanhydrid, ausgewählt ist.
7. Trockengelegtes Vliesmaterial nach Anspruch 6, wobei die gepfropfte Polyolefinkomponente
der Zweikomponentenfasern mit Maleinsäure oder Maleinsäureanhydrid gepfropft worden
ist.
8. Trockengelegtes Vliesmaterial nach einem der Ansprüche 1 - 7, wobei die Zweikomponentenfasern
Mantel-Kern-Fasern sind, bei denen die niedriger schmelzende Polyolefinkomponente
den Mantel ausmacht und die hochschmelzende Polyolefinkomponente den Kern ausmacht.
9. Trockengelegtes Vliesmaterial nach einem der vorstehenden Ansprüche, wobei die hochschmelzende
Polyolefinkomponente Polypropylen umfasst und die niedrigschmelzende Polyolefinkomponente
mindestens ein Polyolefin umfasst, das aus LLDPE, HDPE und LDPE ausgewählt ist.
10. Trockengelegtes Vliesmaterial nach einem der vorstehenden Ansprüche, wobei der Unterschied
in den Schmelzpunkten zwischen der niedrigschmelzenden Komponente und der hochschmelzenden
Komponente der Zweikomponentenfasern mindestens etwa 20°C ist.
11. Trockengelegtes Vliesmaterial nach einem der Ansprüche 1 - 10, wobei die hochschmelzende
Polyolefinkomponente ein erstes Polypropylen umfasst und die niedrigschmelzende Polyolefinkomponente
ein zweites Polypropylen oder ein Polypropylencopolymer mit einem mindestens 5°C niedrigeren
Schmelzpunkt als beim ersten Polypropylen umfasst.
12. Trockengelegtes Vliesmaterial nach einem der vorstehenden Ansprüche, wobei die Faserbahn
5 - 50 Gew.-% Zweikomponentenfasern und 50 - 95 Gew.-% zusätzliches Fasermaterial,
typischerweise 10 - 40 Gew.-% Zweikomponentenfasern und 60 - 90 Gew.-% zusätzliches
Fasermaterial, z.B. 15 - 25 Gew.-% Zweikomponentenfasern und 75 - 85 Gew.-% zusätzliches
Fasermaterial, umfasst.
13. Verfahren zum Herstellen eines trockengelegten Vliesmaterials, umfassend das Bilden
einer Faserbahn unter Verwendung einer Ausrüstung zum Trockenlegen von Vlies, wobei
die Bahn Zweikomponentenfasern und mindestens ein zusätzliches Fasermaterial umfasst,
wobei die Zweikomponentenfasern eine niedrigschmelzende Polyolefinkomponente und eine
hochschmelzende Polyolefinkomponente umfassen, wobei die niedrigschmelzende Polyolefinkomponente
einen mindestens 4°C niedrigeren Schmelzpunkt als den Schmelzpunkt der hochschmelzenden
Polyolefinkomponente aufweist, die niedrigschmelzende Polyolefinkomponente mindestens
einen Teil der Faseroberfläche ausmacht und eine nichtgepfropfte Polyolefinkomponente
und eine gepfropfte Polyolefinkomponente umfasst, wobei die gepfropfte Polyolefinkomponente
mit einer ungesättigten Dicarbonsäure oder einem Anhydrid davon gepfropft worden ist,
und Binden der Faserbahn, um das trockengelegte Vliesmaterial zu erhalten.
14. Verfahren nach Anspruch 13, wobei das zusätzliche Fasermaterial aus Naturfasern und
regenerierten Fasern ausgewählt ist, z.B. aus Cellulosefasern, Viscosefasern und Lyocellfasern
ausgewählt ist.
15. Verfahren nach Anspruch 14, wobei das zusätzliche Fasermaterial Celluloseschliffzellstofffasern
umfasst.
16. Verfahren nach einem der Ansprüche 13 - 15, wobei die gepfropfte Polyolefinkomponente
der Zweikomponentenfasern mit einer Verbindung gepfropft worden ist, die aus Maleinsäure,
Maleinsäureanhydrid und Derivaten davon, wie Citraconsäure, Citraconsäureanhydrid
und Pyrocinchonsäureanhydrid; Fumarsäure und Derivaten davon; ungesättigten Derivaten
der Malonsäure, wie 3-Buten-1,1-dicarbonsäure, Benzylidenmalonsäure und Isopropylidenmalonsäure;
und ungesättigten Derivaten der Bernsteinsäure, wie Itaconsäure und Itaconsäureanhydrid,
ausgewählt ist.
17. Verfahren nach Anspruch 16, wobei die gepfropfte Polyolefinkomponente der Zweikomponentenfasern
mit Maleinsäure oder Maleinsäureanhydrid gepfropft worden ist.
18. Verfahren nach einem der Ansprüche 13 - 17, wobei die Zweikomponentenfasern Mantel-Kern-Fasern
sind, bei denen die niedriger schmelzende Polyolefinkomponente den Mantel ausmacht
und die hochschmelzende Polyolefinkomponente den Kern ausmacht.
19. Verfahren nach einem der Ansprüche 13 - 18, wobei die hochschmelzende Polyolefinkomponente
Polypropylen umfasst und die niedrigschmelzende Polyolefinkomponente mindestens ein
Polyolefin umfasst, das aus LLDPE, HDPE und LDPE ausgewählt ist.
20. Verfahren nach einem der Ansprüche 13 - 19, wobei der Unterschied in den Schmelzpunkten
zwischen der niedrigschmelzenden Komponente und der hochschmelzenden Komponente der
Zweikomponentenfasern mindestens etwa 20°C ist.
21. Verfahren nach einem der Ansprüche 13 - 20, wobei die hochschmelzende Polyolefinkomponente
ein erstes Polypropylen umfasst und die niedrigschmelzende Polyolefinkomponente ein
zweites Polypropylen oder ein Polypropylencopolymer mit einem mindestens 5°C niedrigeren
Schmelzpunkt als beim ersten Polypropylen umfasst.
22. Verfahren nach einem der Ansprüche 13 - 21, wobei die Faserbahn 5 - 50 Gew.-% Zweikomponentenfasern
und 50 - 95 Gew.-% zusätzliches Fasermaterial, typischerweise 10 - 40 Gew.-% Zweikomponentenfasern
und 60 - 90 Gew.-% zusätzliches Fasermaterial, z.B. 15 - 25 Gew.-% Zweikomponentenfasern
und 75 - 85 Gew.-% zusätzliches Fasermaterial umfasst.
23. Zweikomponentenfaser zur Herstellung trockengelegter Vliesmaterialien, wobei die Faser
eine niedrigschmelzende Polyolefinkomponente und eine hochschmelzende Polyolefinkomponente
umfasst, wobei die niedrigschmelzende Polyolefinkomponente einen mindestens 4°C niedrigeren
Schmelzpunkt als den Schmelzpunkt der hochschmelzenden Polyolefinkomponente aufweist,
die niedrigschmelzende Polyolefinkomponente mindestens einen Teil der Faseroberfläche
ausmacht und eine nichtgepfropfte Polyolefinkomponente und eine gepfropfte Polyolefinkomponente
umfasst, wobei die gepfropfte Polyolefinkomponente mit einer ungesättigten Dicarbonsäure
oder einem Anhydrid davon gepfropft worden ist, wobei die niedrigschmelzende Polyolefinkomponente,
die mindestens einen Teil der Faseroberfläche ausmacht und die eine nichtgepfropfte
Polyolefinkomponente und eine gepfropfte Polyolefinkomponente umfasst, so gestaltet
ist, dass das Gewichtsverhältnis von gepfropftem Polyolefin zu nichtgepfropftem Polyolefin
im Bereich von 1:99 bis 50:50 liegt.
1. Matière non tissée formée par voie sèche, comprenant des fibres bicomposantes et au
moins un matériau fibreux supplémentaire, lesdites fibres bicomposantes comprenant
un composant à base de polyoléfine à bas point de fusion et un composant à base de
polyoléfine à haut point de fusion, où le composant à base de polyoléfine à bas point
de fusion présente un point de fusion inférieur d'au moins 4°C au point de fusion
du composant à base de polyoléfine à haut point de fusion, le composant à base de
polyoléfine à bas point de fusion constituant au moins une partie de la surface de
la fibre et comprenant un composant à base de polyoléfine non greffé et un composant
à base de polyoléfine greffé, où le composant à base de polyoléfine greffé a été greffé
avec un acide dicarboxylique insaturé ou un de ses anhydrides,
dans laquelle ledit au moins un matériau fibreux supplémentaire est choisi parmi un
matériau fibreux naturel ou régénéré,
dans laquelle le composant à base de polyoléfine à bas point de fusion constituant
au moins une partie de la surface de la fibre et comprenant un composant à base de
polyoléfine non greffé et un composant à base de polyoléfine greffé est tel que le
rapport pondéral de la polyoléfine greffée à la polyoléfine non greffée se situe dans
la gamme de 1:99 à 50:50 ;
et dans laquelle les fibres bicomposantes ayant une affinité de liaison pour les fibres
naturelles ou régénérées sont telles que la matière non tissée présente une teneur
en poussières dans la méthode d'essai A de poussières normalisée non supérieure à
environ 10 mg.
2. Matière selon la revendication 1, dans laquelle le composant à base de polyoléfine
à bas point de fusion constituant au moins une partie de la surface de la fibre et
comprenant un composant à base de polyoléfine non greffé et un composant à base de
polyoléfine greffé est tel que le rapport pondéral de la polyoléfine greffée à la
polyoléfine non greffée se situe dans la gamme de 1,5:98,5 à 30:70, tel que 2:98 à
20:80, 3:97 à 15:85 ; le plus préférentiellement dans la gamme de 5:95 à 10:90.
3. Matière selon l'une quelconque des revendications 1-2, dans laquelle les fibres naturelles
et les fibres régénérées sont choisies dans le groupe constitué de la fibre de cellulose,
de la fibre de viscose, et des fibres Lyocell.
4. Matière non tissée formée par voie sèche selon la revendication 3, dans laquelle le
matériau fibreux supplémentaire comprend des fibres de pâte de cellulose en flocons.
5. Matière non tissée formée par voie sèche selon l'une quelconque des revendications
1-4, dans laquelle la matière non tissée présente une teneur en poussières dans la
méthode d'essai A de poussières normalisée non supérieure à environ 5 mg, plus préférentiellement
non supérieure à environ 4 mg, encore plus préférentiellement non supérieure à environ
3 mg, le plus préférentiellement non supérieure à environ 2 mg.
6. Matière non tissée formée par vole sèche selon l'une quelconque des revendications
1-5, dans laquelle le composant à base de polyoléfine greffé des fibres bicomposantes
a été greffé avec un composé choisi parmi : l'acide maléique, l'anhydride maléique
et leurs dérivés tels que l'acide citraconique, l'anhydride citraconique, l'anhydride
citraconique et l'anhydride pyrocinchonique ; l'acide fumarique et ses dérivés ; les
dérivés insaturés de l'acide malonique tels que l'acide 3-butène-1,1-dicarboxylique,
l'acide benzylidène-malonique et l'acide isopropylidènemalonique ; et les dérivés
insaturés de l'acide succinique tels que l'acide itaconique et l'anhydride itaconique.
7. Matière non tissée formée par voie sèche selon la revendication 6, dans laquelle le
composant à base de polyoléfine greffé des fibres bicomposantes a été greffé avec
de l'acide maléique ou de l'anhydride n'aléique.
8. Matière non tissée formée par voie sèche selon l'une quelconque des revendications
1-7, dans laquelle les fibres bicomposantes sont des fibres âme/gaine dans lesquelles
le composant à base de polyoléfine à point de fusion inférieur constitue la gaine
et le composant à base de polyoléfine à haut point de fusion constitue l'âme.
9. Matière non tissée formée par voie sèche selon l'une quelconque des revendications
précédentes, dans laquelle le composant à base de polyoléfine à haut point de fusion
comprend du polypropylène et le composant à base de polyoléfine à bas point de fusion
comprend au moins une polyoléfine choisie parmi LLDPE, HDPE et LDPE.
10. Matière non tissée formée par voie sèche selon l'une quelconque des revendications
précédentes, dans laquelle la différence de point de fusion entre le composant à bas
point de fusion et le composant à haut point de fusion des fibres bicomposantes est
d'au moins environ 20°C,
11. Matière non tissée formée par voie sèche selon l'une quelconque des revendications
1-10, dans laquelle le composant à base de polyoléfine à haut point de fusion comprend
un premier polypropylène, et le composant à base de polyoléfine à bas point de fusion
comprend un second polypropylène ou un copolymère de polypropylène avec un point de
fusion inférieur d'au moins 5°C au premier polypropylène.
12. Matière non tissée formée par voie sèche selon l'une quelconque des revendications
précédentes, dans laquelle la bande fibreuse comprend 5-50% en poids des fibres bicomposantes
et 50-95% en poids d'un matériau fibreux supplémentaire, typiquement 10-40% en poids
des fibres bicomposantes et 60-90% en poids du matériau fibreux supplémentaire, par
exemple 15-25% en poids des fibres bicomposantes et 75-85% en poids du matériau fibreux
supplémentaire.
13. Procédé de production d'une matière non tissée formée par voie sèche, comprenant la
formation d'une bande fibreuse au moyen d'un matériel pour non tissé par voio sèche,
la bande comprenant des fibres bicomposantes et au moins un matériau fibreux supplémentaire,
lesdites fibres bicomposantes comprenant un composant à base de polyoléfine à bas
point de fusion et un composant à base de polyoléfine à haut point de fusion, où le
composant à base de polyoléfine à bas point de fusion présente un point de fusion
inférieur d'au moins 4°C au point de fusion du composant à base de polyoléfine à haut
point de fusion, le composant à base de polyoléfine à bas point de fusion constituant
au moins une partie de la surface de la fibre et comprenant un composant à base de
polyoléfine non greffé et un composant à base de polyoléfine greffé, où le composant
à base de polyoléfine greffé a été greffé avec un acide dicarboxylique insaturé ou
un de ses anhydrides, et le liage de la bande fibreuse avec pour résultat la matière
non tissée formée par voie sèche.
14. Procédé selon la revendication 13, dans lequel le matériau fibreux supplémentaire
est choisi parmi les fibres naturelles et les fibres régénérées, par exemple choisi
parmi les fibres de cellulose, les fibres de viscose et les fibres Lyocell.
15. Procédé selon la revendication 14, dans lequel le matériau fibreux supplémentaire
comprend des fibres de pâte de cellulose en flocons.
16. Procédé selon l'une quelconque des revendications 13-15, dans lequel le composant
à base de polyoléfine greffé des fibres bicomposantes a été greffé avec un composé
choisi parmi : l'acide maléique, l'anhydride maléique et leurs dérivés tels que l'acide
citraconique, l'anhydride citraconique, l'anhydride citraconique et l'anhydride pyrocinchonique
; l'acide fumarique et ses dérivés ; les dérivés insaturés de l'acide malonique tels
que l'acide 3-butène-1,1-dicarboxylique, l'acide benzylidène-malonique et l'acide
isopropylidènemalonique ; et les dérivés insaturés de l'acide succinique tels que
l'acide itaconique et l'anhydride itaconique.
17. Procédé selon la revendication 16, dans lequel le composant à base de polyoléfine
greffé des fibres bicomposantes a été greffé avec de l'acide maléique ou de l'anhydride
maléique.
18. Procédé selon l'une quelconque des revendications 13-17, dans lequel les fibres bicomposantes
sont des fibres âme/gaine dans lesquelles le composant à base de polyoléfine à point
de fusion inférieur constitue la gaine et le composant à base de polyoléfine à haut
point de fusion constitue l'âme.
19. Procédé selon l'une quelconque des revendications 13-18, dans lequel le composant
à base de polyoléfine à haut point de fusion comprend du polypropylène et le composant
à base de polyoléfine à bas point de fusion comprend au moins une polyoléfine choisie
parmi LLDPE, HDPE et LDPE.
20. Procédé selon l'une quelconque des revendications 13-19, dans lequel la différence
de point de fusion entre le composant à bas point de fusion et le composant à haut
point de fusion des fibres bicomposantes est d'au moins environ 20°C.
21. Procédé selon l'une quelconque des revendications 13-20, dans lequel le composant
à base de polyoléfine à haut point de fusion comprend un premier polypropylène, et
le composant à base de polyoléfine à bas point de fusion comprend un second polypropylène
ou un copolymère de polypropylène avec un point de fusion inférieur d'au moins 5°C
au premier polypropylène.
22. Procédé selon l'une quelconque des revendications 13-21, dans lequel la bande fibreuse
comprend 5-50% en poids des fibres bicomposantes et 50-95% en poids d'un matériau
fibreux supplémentaire, typiquement 10-40% en poids des fibres bicomposantes et 60-90%
en poids du matériau fibreux supplémentaire, par exemple 15-25% en poids des fibres
bicomposantes et 75-85% en poids du matériau fibreux supplémentaire.
23. Fibre bicomposante pour la production de matières non tissées formées par voie sèche,
la fibre comprenant un composant à base de polyoléfine à bas point de fusion et un
composant à base de polyoléfine à haut point de fusion, où le composant à base de
polyoléfine à bas point de fusion présente un point de fusion inférieur d'au moins
4°C au point de fusion du composant à base de polyoléfine à haut point de fusion,
le composant à base de polyoléfine à bas point de fusion constituant au moins une
partie de la surface de la fibre et comprenant un composant à base de polyoléfine
non greffé et un composant à base de polyoléfine greffé, où le composant à base de
polyoléfine greffé a été greffé avec un acide dicarboxylique insaturé ou un de ses
anhydrides, dans laquelle le composant à base de polyoléfine à bas point de fusion
constituant au moins une partie de la surface de la fibre et comprenant un composant
à base de polyoléfine non greffé et un composant à base de polyoléfine greffé est
tel que le rapport pondéral de la polyoléfine greffée à la polyoléfine non greffée
se situe dans la gamme de 1:99 à 50:50.