U.S. patent application number 12/304622 was filed with the patent office on 2010-01-28 for lyocell staple fiber.
This patent application is currently assigned to LENZING AKTIENGESELLSCHAFT. Invention is credited to Franz Dumberger, Christoph Schrempf, Wolfgang Uhlir.
Application Number | 20100021711 12/304622 |
Document ID | / |
Family ID | 38531755 |
Filed Date | 2010-01-28 |
United States Patent
Application |
20100021711 |
Kind Code |
A1 |
Schrempf; Christoph ; et
al. |
January 28, 2010 |
Lyocell Staple Fiber
Abstract
The present invention relates to Lyocell staple fiber consisting
of a plurality of cut filaments, which is characterized in that at
least part of said cut filaments exhibit an overall cross-sectional
shape which is a bi- or multi-filar cross-sectional shape resulting
from notionally partially overlapping two or more fiber
cross-sectional shapes.
Inventors: |
Schrempf; Christoph; (Bad
Schallerbach, AT) ; Dumberger; Franz; (Schorfling,
AT) ; Uhlir; Wolfgang; (Lenzing, AT) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
1290 Avenue of the Americas
NEW YORK
NY
10104-3800
US
|
Assignee: |
LENZING AKTIENGESELLSCHAFT
Lenzing
AT
|
Family ID: |
38531755 |
Appl. No.: |
12/304622 |
Filed: |
May 29, 2007 |
PCT Filed: |
May 29, 2007 |
PCT NO: |
PCT/AT07/00256 |
371 Date: |
July 17, 2009 |
Current U.S.
Class: |
428/221 ;
264/187; 428/359 |
Current CPC
Class: |
D01D 5/253 20130101;
Y10T 428/2904 20150115; D01F 2/00 20130101; Y10T 428/249921
20150401 |
Class at
Publication: |
428/221 ;
428/359; 264/187 |
International
Class: |
D01F 2/00 20060101
D01F002/00; D01D 5/253 20060101 D01D005/253; D01D 5/38 20060101
D01D005/38 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 14, 2006 |
AT |
A 1015/2006 |
Claims
1. A Lyocell staple fiber consisting of a plurality of cut
filaments, wherein at least part of said cut filaments exhibit an
overall cross-sectional shape which is a bi- or multi-filar
cross-sectional shape resulting from notionally partially
overlapping two or more fiber cross-sectional shapes.
2. The Lyocell staple fiber according to claim 1, wherein at least
part of, preferably all of said partially overlapped
cross-sectional shapes are essentially circular shapes.
3. The Lyocell staple fiber according to claim 2, wherein said two
or more partially overlapped circular shapes have essentially the
same diameter.
4. The Lyocell staple fiber according to claim 2, wherein one or
more of said partially overlapped circular shapes has/have a higher
diameter than the rest of said overlapped circular shapes.
5. The Lyocell staple fiber according to claim 1, wherein said
overall cross-sectional shape is a bi-filar cross-sectional shape
resulting from notionally overlapping two essentially circular
shapes.
6. The Lyocell staple fiber according to claim 1, wherein said
overall cross-sectional shape is a tri-filar cross-sectional shape
resulting from notionally overlapping three essentially circular
shapes.
7. The Lyocell staple fiber according to claim 6, wherein said
three overlapped circular shapes are arranged in a row.
8. The Lyocell staple fiber according to claim 7, wherein said
three overlapped circular shapes are arranged in the form of a
triangle.
9. (canceled)
10. The Lyocell staple fiber according to claim 1, wherein said
overall cross-sectional shape is a quadri-filar cross-sectional
shape resulting from notionally overlapping four essentially
circular shapes.
11. The Lyocell staple fiber according to claim 10, wherein said
four overlapped circular shapes are arranged in a row.
12. The Lyocell staple fiber according to claim 10, wherein said
four overlapped circular shapes are arranged in the form of a
square, a parallelogram, or a rhombus.
13. The Lyocell staple fiber according to claim 10, wherein said
four overlapped circular shapes are arranged in the form of a
triangle, with one of said circular shapes forming the centre of
said triangle.
14. (canceled)
15. The Lyocell staple fiber according to claim 1, wherein said
overall cross-sectional shape is a multi-filar cross-sectional
shape resulting from notionally overlapping five or more,
preferably five or seven essentially circular shapes.
16. The Lyocell staple fiber according to claim 1, wherein at least
one of said partially overlapped cross-sectional shapes is a
non-circular cross-sectional shape.
17. Lyocell staple fiber according to claim 16, wherein said
non-circular cross-sectional shape is a multilobal, preferably
trilobal, or triangular shape.
18. The Lyocell staple fiber according to any of the preceding
claims, wherein essentially all of the cut filaments exhibit
essentially the same overall cross-sectional shape.
19. The Lyocell staple fiber according to claim 1, 2, 3, 4, 5, 6,
7, 8, 10, 11, 12, 13, 15, 16, or 17, wherein said overall
cross-sectional shape is hollow.
20. The Lyocell staple fiber according to claim 1, 2, 3, 4, 5, 6,
7, 8, 10, 11, 12, 13, 15, 16, or 17, wherein it exhibits a fiber
tenacity in conditioned state which is higher by at least 15%,
preferably at least 20%, than the fiber tenacity of a comparison
Lyocell staple fiber of the same decitex, wherein all cut filaments
of said comparison Lyocell staple fiber exhibit an essentially
round cross-section.
21. The Lyocell staple fiber according to claim 1, 2, 3, 4, 5, 6,
7, 8, 10, 11, 12, 13, 15, 16, or 17, wherein it exhibits a
decitex-related flexural rigidity of at least 0.5
mNmm.sup.2/tex.sup.2, preferably more than 0.6
mNmm.sup.2l/tex.sup.2.
22. A process for the manufacture of a Lyocell staple fiber
according to claims 1, comprising the steps of extruding a solution
of cellulose dissolved in an aqueous tertiary amine-oxide through a
spinneret exhibiting a plurality of spinneret orifices whereby
filaments are formed conducting said filaments via an air gap into
a precipitation bath drawing said filaments in said air gap blowing
air on said filaments in said air gap precipitating said filaments
in said precipitation bath cutting said precipitated filaments in
order to form cut filaments, wherein at least part of said
spinneret orifices consists of an assembly of two or more holes
being located adjacent such that when the solution is extruded
through said holes, the filaments extruded from said holes are
partially fused to form one fused filament.
23. The process according to claim 22, wherein at least part of,
preferably all of said holes have a circular shape.
24. The process according to claim 23, wherein all of said holes
have the same diameter.
25. The process according to claim 23, wherein at least one or more
of said holes has/have a higher diameter than the rest of said
holes.
26. (canceled)
27. The process according to claim 22, wherein said spinneret
orifice consists of two to fiver or seven holes, each having a
circular shape.
28-38. (canceled)
39. The process according to any one of claims 22, wherein all of
said spinneret orifices consist of an identical assembly of holes
in terms of the geometrical arrangement, the shape and the size of
said holes.
40. The process according to claim 39, wherein said spinneret
orifices are positioned in a plurality of parallel rows and in
that, within each of said rows, all assemblies of holes are
oriented essentially parallel to each other.
41. The process according to claim 40, wherein said air blown on
said filaments in the air gap is directed onto said filaments in
case of a row arrangement of said holes, essentially parallel to
the direction of said row in case of a triangle arrangement of said
holes, essentially parallel to the direction of one of the base
lines of said triangle in case of a square arrangement of said
holes, essentially parallel to the direction of one of the base
lines of said square in case of other geometrical arrangement of
said holes, essentially parallel to the direction of the main
orientation axis of said arrangement
42-43. (canceled)
44. A product comprising the Lyocell staple fiber according to
claim 1 wherein the product is selected from the group consisting
of medical-, hygiene-, household textiles, technical- and apparel
applications, such as wound dressings, laparotomy pads, bed pads,
tampons, sanitary towels, wipes, incontinence products, pillows,
duvets, towels, carpets, pile fabrics, damask, satin, insulation
materials, reinforcement fiber for polymers, paper or concrete,
textile articles, such as knitted or woven textile articles,
shirtings, velour, chinos, cotton-like hand fabrics and garments
made thereof.
45. The Lyocell fiber according to claim 5, 6, 7, 8, 10, 11, 12, 13
or 15, wherein said filaments exhibit a decitex of from about 0.5
to 8 dtex, preferably 0.5 to 4 dtex.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a Lyocell staple fiber.
[0003] A Lyocell fiber is a celluosic fiber which is spun from a
solution from cellulose in an organic solvent, especially in an
aqueous tertiary amine-oxide. Today, N-methyl-morpholine-N-oxide
(NMMO) is commercially used a solvent to produced Lyocell
fibers.
[0004] 2. Description of the Prior Art
[0005] The process for producing standard Lyocell fibers is well
known from, inter alia, U.S. Pat. No. 4,246,221 or WO 93/19230.
This process is called "amine-oxide process" or also "Lyocell
process".
[0006] Lyocell staple fiber is a product resulting from cutting a
plurality of (endless) filaments which are obtained by spinning the
cellulose solution through a spinneret and precipitating the spun
filaments.
[0007] Typically, the cross-sectional shape of Lyocell fibers is
essentially round. This is in contrast to standard viscose fibers,
which exhibit a rather serrated cross-sectional shape.
[0008] Various processes to produce cellulosic fibers with defined
non-circular cross-sectional shapes have been proposed. For
example, EP 0 301 874 A discloses a process for the manufacture of
so-called multi-lobal cellulosic staple fibers. A further process
for the manufacture of cellulosic staple fibers by spinning of a
spinning solution through a spinneret with multi-lobal spinneret
holes is disclosed in WO 04/85720. Cellulosic fibers of a
"Y"-shaped cross-section are also mentioned in GB-A-2 085 304.
[0009] JP-A 61-113812 and the publication "Verzug, Verstreckung und
Querschnittsmodifizierung beim Viskosespinnen", Treiber E.,
Chemiefasern 5 (1967) 344 348 disclose the manufacture of (endless)
cellulosic filaments by extruding a spinning solution through a
spinneret with multi-lobal spinneret holes.
[0010] All the above references are limited to the production of
cellulosic fibers via the viscose process. Viscose fibers are quite
distinct from Lyocell fibers in terms of their physical and textile
properties.
[0011] The manufacture of a "Y"-shaped Lyocell fiber is mentioned
in EP 0 574 870 A.
[0012] JP 10-140429 A discloses regenerated cellulose fibers which
are produced by spinning a viscose solution through a spinneret
exhibiting arrangements of fiber-forming holes which are located
adjacent. Upon spinning the solution through the spinneret, the
filaments extruded through these fiber-forming holes are fused to
form one fiber exhibiting an anomal cross-sectional shape.
SUMMARY OF THE INVENTION
[0013] It is an object of the present invention to provide a
Lyocell staple fiber having a defined non-circular cross-sectional
shape.
[0014] This object is solved by a Lyocell staple fiber consisting
of a plurality of cut filaments, which is characterized in that at
least part of said cut filaments exhibit an overall cross-sectional
shape which is a bi- or multi-filar cross-sectional shape resulting
from notionally partially overlapping two or more fiber
cross-sectional shapes.
[0015] The term "bi- or multi-filar" cross-sectional shape, for the
purposes of the present invention, means a cross-sectional shape
which results from notionally partially overlapping two or more
fiber cross-sectional shapes.
[0016] I.e. a bi-filar cross-sectional shape is a shape resulting
from partially overlapping two fiber cross-sectional shapes. A
tri-filar cross-sectional shape is a shape resulting from partially
overlapping three fiber cross-sectional shapes, and so on. This
resulting cross-sectional shape will in the following also be
referred to as the "overall cross-sectional shape", in contrast to
the single cross-sectional shapes which are partially
overlapped.
[0017] If in the following terms such as "cross-sectional shape of
the staple fiber" are used, this is to be understood as referring
to the overall cross-sectional shape of the filaments which are
constituting the staple fiber according to the invention.
[0018] In a preferred embodiment, at least part of, and preferably
all of said partially overlapped cross-sectional shapes are
essentially circular shapes.
[0019] A bi- or multi-filar cross-sectional shape according to this
preferred embodiment, therefore, exhibits several sections in the
form of segments of circles, i.e. those segments of the circular
shapes which are not overlapped. Furthermore, the bi- or multifilar
cross-sectional shape exhibits notches or indentations in those
sections where the circular shapes are notionally overlapped.
[0020] Said two or more partially overlapped circular shapes may
have essentially the same diameter. Alternatively, one or more of
said partially overlapped circular shapes may have a higher
diameter than the rest of said overlapped circular shapes. This
means that the overall resulting cross-sectional shape consists of
a mixture of smaller and larger circular shapes which are partially
overlapped.
[0021] As will be described in more detail below, the Lyocell
staple fiber according to the present invention may be produced by
spinning a cellulose solution through a spinneret wherein at least
part of said spinneret orifices consists of an assembly of two or
more holes being located adjacent such that when the solution is
extruded through said holes, the filaments extruded from said holes
are partially fused to form one fused filament.
[0022] This means that in order to produce a Lyocell staple fiber
the bi- or multi-filar cross-sectional shape of which is a mixture
of smaller and larger circular shapes which are partially
overlapped, as mentioned above, a cellulose solution may be
extruded through a certain geometrical arrangement of adjacent
circular holes with different diameter.
[0023] This not only results in a specific overall cross-sectional
shape as already defined, but furthermore, inventive staple fiber
of this kind exhibits surprisingly high crimp values.
[0024] Without wishing to be bound to any theory, it is believed
that the high crimp of this embodiment of inventive staple fiber
results from the fact that, given a certain overall extrusion
velocity and a certain overall draw ratio in the air gap, if
filaments are extruded from spinning holes with different
diameters, the resulting single filaments which are fused together
to form a fused filament have different tensile properties,
resulting in a certain amount of natural tension and, hence,
natural crimp, in the fused filament.
[0025] In a preferred embodiment, the overall cross-sectional shape
of the fiber according to the invention is a bi-filar
cross-sectional shape resulting from notionally overlapping two
essentially circular shapes.
[0026] In another preferred embodiment, said overall
cross-sectional shape is a tri-filar cross-sectional shape
resulting from notionally overlapping three essentially circular
shapes.
[0027] Said three overlapped circular shapes may be arranged in a
row or in the form of a triangle. Said triangle preferably may be
an essentially isosceles triangle.
[0028] In another preferred embodiment, said overall
cross-sectional shape is a quadri-filar cross-sectional shape
resulting from notionally overlapping four essentially circular
shapes.
[0029] Said four overlapped circular shapes may alternatively be
arranged in a row, in the form of a square, a parallelogram or a
rhombus, or in the form of a triangle, with one of said circular
shapes forming the centre of said triangle.
[0030] Lyocell staple fiber comprising filaments with a bi-, tri-
or quadri-filar cross-sectional shape as described above may
exhibit a decitex of from 0.5 to 8 dtex. Staple fiber of this
decitex is especially useful for textile applications. In the field
of absorbent products, or in the field of fiber fillings or
carpets, staple fiber according to the present invention may be
used in a decitex up to 40 dtex or more.
[0031] The overall cross-sectional shape of the staple fiber
according to the present invention may also be a multi-filar
cross-sectional shape resulting from notionally overlapping five or
more, preferably five or seven essentially circular shapes. In this
embodiment, the fibers typically exhibit a decitex of higher than 6
dtex.
[0032] At least one of the partially overlapped cross-sectional
shapes of the staple fiber according to the present invention may
be a non-circular cross-sectional shape.
[0033] I.e. the overall cross-sectional shape of a filament
component of the staple fiber according to the invention may be a
mixture of partially overlapped circular and non-circular
cross-sectional shapes or it may even consist exclusively of
partially overlapped non-circular cross-sectional shapes.
[0034] Said non-circular cross-sectional shape may be a multilobal,
preferably trilobal, or triangular shape.
[0035] An especially preferred embodiment of the staple fiber
according to the present invention is characterized in that
essentially all of the cut filaments exhibit essentially the same
overall cross-sectional shape.
[0036] Staple fiber according to this preferred embodiment has
quite uniform properties in terms of its cross-sectional shape and
the various physical and textile properties achieved thereby.
[0037] In yet a further embodiment, the filament constituting the
Lyocell staple fiber according to the invention may at least partly
exhibit a bi- or multi-filar cross-sectional shape which is hollow.
A hollow structure may be obtained by choosing the spinning
parameters in terms of size and distance of the spinning holes such
that the extruded single filaments are not completely fused, but
rather a gap is left in the centre of the formed fused
filament.
[0038] It has surprisingly been found that the Lyocell staple fiber
according to the invention has a significantly higher tenacity than
comparable standard Lyocell staple fiber of the same decitex.
Especially, Lyocell staple fiber according to the present invention
exhibits a fiber tenacity in conditioned state which is higher by
at least 15%, preferably at least 20%, than the fiber tenacity of a
comparison Lyocell staple fiber of the same decitex, wherein all
cut filaments of said comparison Lyocell staple fiber exhibit an
essentially round cross-section.
[0039] Furthermore, Lyocell staple fiber according to the present
invention has a surprisingly high flexural rigidity.
[0040] Especially, Lyocell staple fiber according to the present
invention exhibits a decitex-related flexural rigidity of at least
0.5 mNmm.sup.2/tex.sup.2, preferably more than 0.6
mNmm.sup.2/tex.sup.2.
[0041] The flexural rigidity is measured by a method developed by
the applicant. The measured value is displayed as the relation of
the gradient of the force to path over a linear measuring range,
based on the decitex.
[0042] In order to carry out the measurement, a conditioned fiber
is clamped into a clamping bar and cut with a cutting device to a
length of exactly 5 mm. The clamping bar is moved upwardly at
constant speed by an electric gear. Thereby, the fiber is pressed
onto a small sensor plate which is adapted to a force sensor. The
stiffer the fiber, the higher is the measured force.
[0043] Due to the lack of possibilities to calibrate, no effective
force is given for the calculation of the flexural stiffness.
However, it is possible to make a relative comparison of fibers in
a specified measuring range. Thereby, the gradient is measured in a
linear measuring range of the measured force over the path and
related to the decitex of the fiber.
[0044] A process for the manufacture of a Lyocell staple fiber
according to the present invention comprises the steps of [0045]
extruding a solution of cellulose dissolved in an aqueous tertiary
amine-oxide through a spinneret exhibiting a plurality of spinneret
orifices whereby filaments are formed [0046] conducting said
filaments via an air gap into a precipitation bath [0047] drawing
said filaments in said air gap [0048] blowing air on said filaments
in said air gap [0049] precipitating said filaments in said
precipitation bath [0050] cutting said precipitated filaments in
order to form cut filaments, and is characterized in that [0051] at
least part of said spinneret orifices consists of an assembly of
two or more holes being located adjacent such that when the
solution is extruded through said holes, the filaments extruded
from said holes are partially fused to form one fused filament.
[0052] It has surprisingly been found that if a cellulose solution
in NMMO is extruded through a spinneret as specified above, fused
filaments result which exhibit a very uniform and reproducible bi-
or multi-filar cross-sectional shape.
[0053] In the process according to the present invention,
preferably at least part of, and more preferably all of said
spinneret holes have a circular shape. All of said holes may have
the same diameter.
[0054] Alternatively, one or more of said holes may have a higher
diameter than the rest of said holes. In this case, a
cross-sectional shape results which is a mixture of partially
overlapped smaller and larger circular shapes, as mentioned above.
The ratio of the cross-sectional area of the hole(s) with the
higher diameter to the hole cross-sectional area of the hole(s)
with a smaller diameter is preferably from more than 1:1 to 16:1,
preferably 1.6 to 1 to 2.7 to 1.
[0055] In a further preferred embodiment, said spinneret orifice
consists of two holes, each having a circular shape.
[0056] Said spinneret orifice may also consist of three holes, each
having a circular shape. The three holes may be arranged in a row,
resulting in an overall flat, oblong cross-sectional shape of the
fused filament.
[0057] Furthermore, said three holes may be arranged in the form of
a triangle,--preferably an isosceles triangle. If the diameter of
all the spinning holes is the same, or especially if the diameter
of the hole in the intersection point of the two equal sides of the
isosceles triangle is bigger than the diameter of the other two
holes, the resulting overall cross-sectional shape of the fused
filament will be of a "teddy-bear"-like nature, two of the
partially overlapped circular shapes forming the "ears" of the
bear, and the circular shape of the filament spun from the hole at
the intersection point of the two equal sides of the isosceles
triangle forming the "face".
[0058] Said spinneret orifice may also consist of four holes, each
having a circular shape.
[0059] The four holes may be arranged in a row, again resulting in
an flat and oblong overall cross-sectional shape of the fused
filament.
[0060] Alternatively, said four holes may be arranged in the form
of a square, a parallelogram, or a rhombus. If the diameter of all
the spinning holes is the same, the resulting overall
cross-sectional shape of the fused filament will then resemble a
square, a parallelogram or a rhombus, respectively.
[0061] Said four holes may also be arranged in the form of a
triangle, with one of said holes forming the centre of said
triangle. Again, depending on the diameter of the spinning holes
employed, a triangular or "teddy-bear"-like shape may result.
[0062] Said spinneret orifice may also consist of five or more
holes, preferably five or seven holes, each having a circular
shape. Of course, many different geometrical arrangements of the
holes are possible, resulting in a variety of different
cross-sectional shapes of the fused filaments, which will be shown
in more detail below with reference to the drawings.
[0063] As will already be apparent from the above, the overall
cross-sectional shape of the fused filaments does not only depend
on the number and geometrical arrangement of the spinneret holes
employed in said spinneret orifice, but there is also a strong
correlation to the size of the hole diameters. I.e. by varying the
hole diameters or by providing a geometrical arrangement of holes
with different diameters, the resulting cross-sectional shape of
the fused filament will be strongly influenced.
[0064] In a further embodiment of the present invention, at least
one of said holes has a non-circular shape. Said non-circular shape
may be a multilobal, preferably trilobal, or triangular shape.
[0065] Preferably, all of said spinneret orifices consist of an
identical assembly of holes in terms of the geometrical
arrangement, the shape and the size of said holes. I.e. in this
embodiment all assemblies of holes have the same geometrical
arrangement, and the respective sizes and shapes of the holes
within said arrangement are the same for all the assemblies. By
this embodiment, it has been found that it is possible to obtain a
plurality of fused filaments which exhibit essentially the same bi-
or multifilar cross-sectional shape. It is quite surprising that
such a uniform and reproducible filament (and staple fiber)
cross-section can be obtained in the amine-oxide or Lyocell
process.
[0066] In case of spinning through uniform spinneret orifices,
these may preferably be positioned in a plurality of parallel rows.
Within each of said rows, all assemblies of holes may be oriented
essentially parallel to each other.
[0067] Furthermore, it has been found that the geometrical
arrangement of the spinneret holes, and their respective size and
shape can be optimally reproduced in the fused filaments if the air
which is blown on said filaments in the air gap is directed onto
said filaments in a specific direction:
[0068] In case of a row arrangement of said holes, the blowing
direction should preferably be essentially parallel to the
direction of said row
[0069] in case of a triangle arrangement of said holes, the blowing
direction should preferably be essentially parallel to the
direction of one of the base lines of said triangle
[0070] in case of a square arrangement of said holes, the blowing
direction should preferably be essentially parallel to the
direction of one of the base lines of said square
[0071] in case of other geometrical arrangement of said holes, the
blowing direction should preferably be essentially parallel to the
direction of the main orientation axis of said arrangement.
[0072] Examples for the main orientation axis of several
geometrical arrangements are given below with regard to the
drawings.
[0073] The diameter of said holes in said hole assembly may be from
35 to 200 .mu.m. In case of non-circular holes, the term "diameter"
means the diameter of the circle which can be circumscribed around
the non-circular shape. As already mentioned, holes of different
diameter may be employed in one hole assembly.
[0074] The distance from the centre of one hole to the centre of
the next adjacent hole in said hole assembly may preferably be from
100 to 500 .mu.m, preferably from 150 to 250 .mu.m. The distance
may be adjusted by the skilled artisan in dependency of the desired
overall cross-sectional shape of the fused filament. By
appropriately adjusting the respective distance between the holes
and the respective hole diameters, a staple fiber with a hollow
cross-sectional shape may be produced.
[0075] The Lyocell staple fiber according to the present invention
may be used in a variety of end-uses, such as medical-, hygiene-,
household textiles-, technical- and apparel applications,
especially wound dressings, laparotomy pads, bed pads, tampons,
sanitary towels, wipes, incontinence products, pillows, duvets,
towels, carpets, pile fabrics, damask, satin, insulation materials,
reinforcement fiber for polymers, paper or concrete, textile
articles, such as knitted or woven textile articles, shirtings,
velour, chinos, cotton-like hand fabrics and garments made
thereof.
[0076] Especially, the Lyocell staple fiber according to the
invention is useful in any application where a stiffer, crisper,
more "cotton-like" hand, or altered thermal and moisture management
properties or different optics are desirable.
[0077] Preferred embodiments of the present invention will now be
described by way of the drawings and examples.
BRIEF DESCRIPTION OF THE DRAWINGS
[0078] FIG. 1 shows schematically a spinneret orifice suitable for
the production of filaments with a bi-filar cross-sectional shape,
the preferable direction of blowing air, and possible overall
cross-sectional shapes of filaments spun from said spinneret
orifice.
[0079] FIGS. 2A) and 2B) show schematically two different spinneret
orifices suitable for the production of filaments with tri-filar
cross-sectional shapes, the preferable direction of blowing air,
and possible overall cross-sectional shapes of filaments spun from
said spinneret orifices.
[0080] FIGS. 3A) to 3C) show schematically three different
spinneret orifices suitable for the production of filaments with a
quadri-filar cross-sectional shape, the preferable direction of
blowing air, and possible overall cross-sectional shapes of
filaments spun from said spinneret orifices.
[0081] FIGS. 4A) to 4B) show schematically two further spinneret
orifices suitable for the production of filaments with a
quadri-filar cross-sectional shape, the preferable direction of
blowing air, and possible overall cross-sectional shapes of
filaments spun from said spinneret orifices.
[0082] FIGS. 5A) to 5B) show schematically two different spinneret
orifices suitable for the production of filaments with a
cross-sectional shape composed of five fiber cross-sectional
shapes, the preferable direction of blowing air, and possible
overall cross-sectional shapes of filaments spun from said
spinneret orifices.
[0083] FIGS. 6A) to 6B) show schematically two further spinneret
orifices suitable for the production of filaments with a
cross-sectional shape composed of five fiber cross-sectional
shapes, the preferable direction of blowing air, and possible
overall cross-sectional shapes of filaments spun from said
spinneret orifices.
[0084] FIGS. 7A) to 7B) show schematically two different spinneret
orifices suitable for the production of filaments with a
cross-sectional shape composed of seven fiber cross-sectional
shapes, the preferable direction of blowing air, and possible
overall cross-sectional shapes of filaments spun from said
spinneret orifices.
[0085] FIGS. 8A) to 8D) show two embodiments of producing staple
fiber according to the invention with a tri-filar cross-sectional
shape.
[0086] FIGS. 9A) to 9B) show a further embodiment of producing
staple fiber according to the present invention with a tri-filar
cross-sectional shape.
[0087] FIG. 10 shows the tri-filar cross-sectional shape of a
Lyocell staple fiber according to the present invention.
[0088] FIG. 11 shows the tri-filar cross-sectional shape of a
further Lyocell staple fiber according to the present invention
[0089] FIG. 12 shows the quadri-filar cross-sectional shape of a
Lyocell staple fiber according to the present invention with a
hollow structure.
[0090] According to FIG. 1, a spinneret orifice for the production
of Lyocell staple fiber with a bi-filar cross-sectional shape
consists of two spinneret holes (left side). The holes may be of
the same or different diameter. An optionally smaller hole diameter
is indicated by a smaller circle, and vice versa (this applies for
all FIGS. 1 to 7).
DETAILED DESCRIPTION OF THE INVENTION
[0091] The shaded structures shown on the right side of FIG. 1 show
the two potential overall cross-sectional shapes of a fused
filament spun through the spinneret orifice at the left side. In
the case of two holes with the same large diameter, a bi-filar
cross-section composed of two partially overlapping comparatively
large circles results. In case that one of the two holes has a
smaller diameter, a cross-sectional shape such as the shaded
structure shown at the right end of FIG. 1 results, wherein one
larger circle is partially overlapping with a smaller circle.
[0092] The arrow in FIG. 1 indicates the preferred direction in
which blowing air should be directed onto the extruded filaments
such as to achieve the best results in terms of reproducibility and
uniformity of the cross-sectional shapes of the fused
filaments.
[0093] FIGS. 2 to 7 are based on the same principal structure as
FIG. 1: On the left side, the geometrical arrangement of a
spinneret structure is shown. Right therefrom, several possible
fiber cross-sectional shapes are shown (shaded structures), in
dependence on the respective hole diameters (small or large).
Furthermore, in each of these figures, the preferred direction of
the blowing air is indicated.
[0094] Therefore, in the following only a few comments are to be
made with regard to FIGS. 2 to 7:
[0095] With regard to FIG. 2A), this shows a tri-filar
cross-sectional shape in a row form, if holes of the same diameter
are used. The blowing direction preferably is essentially parallel
to the row.
[0096] FIG. 2B) shows possible tri-filar cross-section shapes in a
triangular configuration. Especially if the hole in the
intersection point of the two equal sides of the isosceles triangle
is bigger (this is indicated by bold lines in the triangular hole
configuration on the left side in FIG. 2B), a "teddy-bear"-like
shape (the shaded structure in the middle) results. The blowing
direction preferably is essentially parallel to the base line of
the triangle of the spinning holes.
[0097] FIGS. 3A to 3C) show various embodiments of overall
quadri-filar cross-sectional shapes. The preferred blowing
direction, indicated by the arrow, is preferably the same for all
the shown embodiments 3A) to 3C). In the case of FIG. 3A) (hole
arrangement in a column), the blowing direction is preferably
essentially parallel to the row. In the case of FIG. 3B) (hole
arrangement in a square), the blowing direction is preferably
essentially parallel to one of the base lines of the square. In the
case of FIG. 3C), the preferred blowing direction is essentially
parallel to the main orientation axis of the geometrical
arrangement of the spinneret holes. Alternatively, the preferred
blowing direction may be essentially parallel to the main diagonal
of the square of FIG. 3B), or, in the case of FIG. 3C), may be
essentially parallel to the axis defined by the connection between
the uppermost and the lowermost of the holes.
[0098] In FIGS. 4A) and 4B) the respective main orientation axis of
the geometrical arrangements shown is indicated with a dotted line.
The cross-sectional shapes which are obtainable from the hole
arrangement shown depending on the respective hole diameters are
self-explaining. The shaded structure according to Figure A) shows
a hollow cross-sectional structure which is obtainable by suitably
choosing the respective distances of the four spinneret holes.
[0099] The preferred blowing direction with regard to both FIGS.
4A) and 4B) is essentially parallel to the main orientation axis as
indicated therein.
[0100] The same applies to FIGS. 5A) and 5B), showing
cross-sectional shapes resulting from spinning the solution through
a spinneret orifice with five adjacent spinneret holes.
[0101] FIGS. 6 and 7 show further embodiments, including
cross-sectional shapes resulting from spinning the solution through
a spinneret orifice with seven adjacent spinneret holes (FIG. 7)
and including hollow cross-sectional shapes.
Examples
Example 1
[0102] FIGS. 8 and 9 demonstrate the influence of the direction of
blowing air on the obtainable cross-sectional shape of the staple
fiber of the invention.
[0103] In each case, a spinneret with various spinneret orifices
each consisting of three holes, arranged in the form of a triangle,
were used. In each orifice, two of the holes had a diameter of 80
.mu.m, and one of the holes had a diameter of 120 .mu.m. The
distance from the center of the bigger hole to the center of the
adjacent holes was 250 .mu.m each.
[0104] FIGS. 8A, 8B, and 9A, respectively, show the respective
spinneret configuration and the direction of the blowing air
employed.
[0105] All other spinning parameters being constant, the only
variation resided in the direction of the blowing air (indicated by
the arrows in FIGS. 8A), 8B) and 9A), respectively).
[0106] As apparent from FIG. 8C) (showing the result of the
experiment according to FIGS. 8A) and FIG. 8D) (showing the result
of the experiment according to FIG. 8B), as compared with FIG. 9B)
(showing the result of the experiment according to FIG. 9A), the
best uniformity in fiber cross-sectional shape and reproduction of
the original spinneret hole configuration is achieved with the test
arrangement according of FIG. 9A), i.e. where the air is blown onto
the filaments in a direction essentially parallel to the base line
of the triangle defined by the two smaller holes, respectively.
Example 2
[0107] FIGS. 10 and 11 show the cross-sectional shapes of Lyocell
staple fiber according to the present invention, produced from a
spinneret configuration as described above with regard to FIGS. 8
and 9.
[0108] A standard spinning solution of 13% cellulose in NMMO was
spun at 110.degree. C. through the spinneret configuration as
described, and was led through an air gap with a length of around
20 mm.
[0109] Blowing air was directed onto the extruded filaments. The
blowing direction was essentially parallel to the base line of the
triangle defined by the two smaller spinneret holes (cf. FIG.
9A).
[0110] Both FIGS. 10 and FIGS. 11 show very uniform cross-sectional
shapes of the filaments obtained, and good reproduction of the
"teddy-bear"-like configuration of the spinning holes.
Example 3
[0111] For the production of the staple fiber depicted in FIG. 12,
spinneret orifices having four holes each were employed. Each hole
had a diameter of 100 .mu.m. The distance from the center of one
hole to its neighboring hole was 500 .mu.m. The holes were arranged
in the form of a rhomboid. The blowing air was directed onto the
spun filaments essentially parallel to the main orientation axis of
the rhomboid (cf. FIG. 4A). A standard spinning solution of 12.3%
cellulose in NMMO was spun at 120.degree. C. through the spinneret
configuration as described, and was led through an air gap with a
length of around 20 mm.
[0112] As apparent from FIG. 12, the resulting staple fiber shows
excellent uniform cross-sectional shape and has a remarkably
reproducible hollow structure.
Example 4
[0113] Applying a constant set of spinning parameters, standard
Lyocell staple fiber with an essentially round cross-section and
Lyocell staple fiber with a tri-filar cross-sectional shape (spun
from a spinneret with orifices as described with regard to example
1 and FIGS. 8 and 9, respectively) with varying decitex were
produced. The following table compares the fiber tenacities of the
fibers obtained:
TABLE-US-00001 TABLE 1 Fiber tenacity Fiber elongation Spinneret
Pulp Decitex (conditioned (conditioned configuration employed
(dtex) state) cN/dtex state (%) Fiber type Round Bacell* 3.3 35.5
14.5 Lyocell-standard Cf. Example 1 Bacell 3.3 40.2 9.9 Lyocell
trifilar - "teddy-bear" Round Bacell 6.7 31.3 12.4 Lyocell-standard
Cf. Example 1 Bacell 6.7 36.5 11.0 Lyocell trifilar - "teddy-bear"
Round KZO3** 6.7 23.7 9.60 Lyocell-standard Cf. Example 1 KZO3 6.7
30.7 11.20 Lyocell trifilar - "teddy-bear" Cf. Example 1 KZO3 18.7
23.3 9.8 Lyocell trifilar - "teddy-bear" *Bacell is a TCF-bleached
eucalyptus sulfite pulp produced by Bahia Brasil. **KZO3 is a
TCF-bleached beech sulfite pulp produced by Lenzing AG.
[0114] It can easily be seen that the Lyocell staple fiber
according to the invention has a significantly higher fiber
tenacity than a standard Lyocell staple with the same decitex.
Example 5
[0115] Lyocell staple fiber according to the present invention
produced with a spinneret configuration as described with regard to
example 1 and FIGS. 8 and 9, respectively, was compared with
various other types of cellulosic fibers in terms of its
decitex-related flexural rigidity. The results are shown in table
2:
TABLE-US-00002 TABLE 2 Fiber Type Pulp Decitex Flexural (mN
mm.sup.2/tex.sup.2) employed (dtex) rigidity Viscose - Standard
KZO3 1.7 0.29 Viscose - Standard KZO3 1.9 0.24 Viscose - Standard
KZO3 1.7 0.29 Modal fiber - produced from a KZO3 6.2 0.41 spinneret
with trilobal holes Modal fiber - produced from a KZO3 6.4 0.34
spinneret with trilobal holes Modal fiber - produced from a KZO3
6.5 0.44 spinneret with trilobal holes Modal fiber - produced from
a KZO3 6.6 0.35 spinneret with trilobal holes Lyocell trifilar -
"teddy-bear" KZO3 16.7 0.51 Lyocell trifilar - "teddy-bear" KZO3
16.7 0.5 Lyocell trifilar - "teddy-bear" Bacell 3.6 0.91 Lyocell
trifilar - "teddy-bear" KZO3 6.4 0.54 Lyocell trifilar -
"teddy-bear" KZO3 6.5 0.69 Lyocell trifilar - "teddy-bear" Saiccor*
6.8 0.63 Lyocell trifilar - "teddy-bear" Bacell 6.5 0.65 Lyocell
trifilar - "teddy-bear" Bacell 6.5 0.68 Lyocell trifilar -
"teddy-bear" Bacell 6.5 0.63 Lyocell trifilar - "teddy-bear" Bacell
6.5 0.62 Lyocell trfilar - "teddy-bear" Bacell 6.4 0.69 Lyocell -
Standard Bacell 6.1 0.37 *Saiccor is a TCF-bleached eucalyptus
sulfite pulp, produced by Saiccor South Africa.
[0116] The Modal fiber in the above example was produced according
to the teaching of PCT/AT/000493 (not pre-published).
[0117] From table 2, it is apparent that the Lyocell staple fiber
with a tri-filar "teddy-bear"-like cross-sectional shape has a
significantly higher decitex-related flexural rigidity than the
other cellulosic fibers observed. Especially the decitex-related
flexural rigidity of the staple fiber according to the invention
was higher than 0.5 mN mm.sup.2/tex.sup.2 in all of the
examples.
* * * * *