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(11) | EP 2 027 314 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
LYOCELL STAPLE FIBER LYOCELL-STAPELFASER FIBRE TEXTILE COUPÉE LYOCELL |
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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). |
[0001] The present invention relates to a process for the manufacture of a Lyocell staple fiber as well as a Lyocell staple fiber obtainable by said process.
[0002] A Lyocell fiber is a cellulosic fiber which is spun from a solution from cellulose in an organic solvent, especially in an aqueous tertiary amine-oxide. Today, N-methylmorpholine-N-oxide (NMMO) is commercially used a solvent to produced Lyocell fibers.
[0003] The process for producing standard Lyocell fibers is well known from, inter alia, US 4,246,221 or WO 93/19230. This process is called-"amine-oxide process" or also "Lyocell process".
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0010] 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.
[0011] It is an object of the present invention to provide a Lyocell staple fiber having a defined non-circular cross-sectional shape.
[0013] The process according to the present invention comprises 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,
- 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
- 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.
[0014] It has surprisingly been found that if a cellulose solution in NMMO is extruded through a spinneret as specified above and under the further conditions as specified above, fused filaments result which exhibit a very uniform and reproducible bi- or multi-filar cross-sectional shape.
[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.
[0018] In the process according to the present invention, prererably at least part of, and more preferably all of said spinneret holes have a circular shape. By employing spinneret orifices all of the holes of which have a circular hole, the Lyocell staple fiber according to the present invention is obtainable.
[0020] 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.
[0021] In a further preferred embodiment, said spinneret orifice consists of two holes, each having a circular shape.
[0022] 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.
[0023] Furthermore, said 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".
[0025] The four holes may be arranged in a row, again resulting in an flat and oblong overall cross-sectional shape of the fused filament.
[0026] 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.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] According to the present invention, 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:
- In case of a row arrangement of said holes, the blowing direction should preferably be essentially parallel to the direction of said row
- 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
- 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
- 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.
[0034] Examples for the main orientation axis of several geometrical arrangements are given below with regard to the drawings.
[0035] The diameter of said holes in said hole assembly may be from 35 to 200 µm. 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.
[0036] 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 µm, preferably from 150 to 250 µm. 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.
[0037] The object of the present invention is, furthermore, solved by a Lyocell staple fiber obtainable by the process of any of claims 2 to 9.
[0038] The Lyocell staple fiber according to the present invention consists 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 and wherein all of said partially overlapped cross-sectional shapes are essentially circular shapes.
[0039] In the Lyocell staple fibre according to the present invention, all of said partially overlapped cross-sectional shapes are essentially circular shapes.
[0040] A bi- or multi-filar cross-sectional shape of the Lyocell staple fibre according to the present invention, 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.
[0041] 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 overal resulting cross-sectional shape consists of a mixture of smaller and larger circular shapes which are partially overlapped.
[0042] As described in more detail above, 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, and by applying the further features of claims 1 and 2.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] In another preferred embodiment, said overall cross-sectional shape is a tri-filar cross-sectional shape resulting from notionally overlapping three essentially circular shapes.
[0048] 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.
[0049] In another preferred embodiment, said overall cross-sectional shape is a quadri-filar cross-sectional shape resulting from notionally overlapping four essentially circular shapes.
[0050] 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.
[0051] 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.
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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 fibre tenacity in conditioned state which is higher by at least 15%, preferably at least 20%, than the fibre 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.
[0057] Furthermore, Lyocell staple fiber according to the present invention has a surprisingly high flexural rigidity.
[0058] Especially, Lyocell staple fiber according to the present invention exhibits a decitex-related flexural rigidity of at least 0.5 mN.mm2/tex2, preferably more than 0.6 mN.mm2/tex2.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] The Lyocell staple fiber according to the present invention may be used in a variety of end-uses, such as medical-, hygeniene-, 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 fibre 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.
[0063] 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.
[0064] Preferred embodiments of the present invention will now be described by way of the drawings and examples.
Short description of the drawings:
[0065]
Figure 1 shows schematically a spinneret orifice suitable for the production of filaments with a bi-filar cross-sectional shape, the direction of blowing air according to the present invention, and possible overall cross-sectional shapes of filaments spun from said spinneret orifice.
Figures 2A) and 2B) show schematically two different spinneret orifices suitable for the production of filaments with tri-filar cross-sectional shapes, the direction of blowing air according to the present invention, and possible overall cross-sectional shapes of filaments spun from said spinneret orifices.
Figures 3A) to 3C) show schematically three different spinneret orifices suitable for the production of filaments with a quadri-filar cross-sectional shape, the direction of blowing air according to the present invention, and possible overall cross-sectional shapes of filaments spun from said spinneret orifices.
Figures 4A) to 4B) show schematically two further spinneret orifices suitable for the production of filaments with a quadri-filar cross-sectional shape, the direction of blowing air according to the present invention, and possible overall cross-sectional shapes of filaments spun from said spinneret orifices.
Figures 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 direction of blowing air according to the present invention, and possible overall cross-sectional shapes of filaments spun from said spinneret orifices.
Figures 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 direction of blowing air according to the present invention, and possible overall cross-sectional shapes of filaments spun from said spinneret orifices.
Figures 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 direction of blowing air according to the present invention, and possible overall cross-sectional shapes of filaments spun from said spinneret orifices.
Figures 8A) to 8D) show two embodiments of producing staple fiber with a tri-filar cross-sectional shape (comparison example).
Figures 9A) to 9B) show an embodiment of producing staple fiber according to the present invention with a tri-filar cross-sectional shape.
Figure 10 shows the tri-filar cross-sectional shape of a Lyocell staple fiber according to the present invention.
Figure 11 shows the tri-filar cross-sectional shape of a further Lyocell staple fiber according to the present invention.
Fig. 12 shows the quadri-filar cross-sectional shape of a Lyocell staple fiber according to the present invention with a hollow structure.
[0066] According to Figure 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 figures 1 to 7).
[0067] The shaded structures shown on the right side of Figure 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 Figure 1 results, wherein one larger circle is partially overlapping with a smaller circle.
[0068] The arrow in Figure 1 indicates the direction in which according to the present invention 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.
[0069] Figures 2 to 7 are based on the same principal structure as Figure 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 direction of the blowing air according to the present invention is indicated.
[0070] Therefore, in the following only a few comments are to be made with regard to Figures 2 to 7:
[0071] With regard to Figure 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.
[0072] Figure 2B) shows possible tri-filar cross-section shapes in a triangular configuration. Especially 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 Figure 2B), a "teddy-bear"-like shape (the shaded structure in the middle) results. The blowing direction is essentially parallel to the base line of the triangle of the spinning holes.
[0073] Figures 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 Figure 3A) (hole arrangement in a column), the blowing direction is essentially parallel to the row. In the case of Figure 3B) (hole arrangement in a square), the blowing direction is essentially parallel to one of the base lines of the square. In the case of Figure 3C), the blowing direction is essentially parallel to the main orientation axis of the geometrical arrangement of the spinneret holes. Alternatively, the blowing direction may be essentially parallel to the main diagonal of the square of Figure 3B), or, in the case of Figure 3C), may be essentially parallel to the axis defined by the connection between the uppermost and the lowermost of the holes.
[0074] In Figures 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.
[0075] The blowing direction according to the present invention with regard to both Figures 4A) and 4B) is essentially parallel to the main orientation axis as indicated therein.
[0076] The same applies to Figures 5A) and 5B), showing cross-sectional shapes resulting from spinning the solution through a spinneret orifice with five adjacent spinneret holes.
[0077] Figures 6 and 7 show further embodiments, including cross-sectional shapes resulting from spinning the solution through a spinneret orifice with seven adjacent spinneret holes (Figure 7) and including hollow cross-sectional shapes.
Examples:
Example 1:
[0078] Figures 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.
[0079] 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 µm, and one of the holes had a diameter of 120 µm. The distance from the center of the bigger hole to the center of the adjacent holes was 250 µm each.
[0080] Figures 8A, 8B, and 9A, respectively, show the respective spinneret configuration and the direction of the blowing air employed.
[0081] All other spinning parameters being constant, the only variation resided in the direction of the blowing air (indicated by the arrows in Figures 8A), 8B) and 9A), respectively).
[0082] As apparent from Figure 8C) (showing the result of the experiment according to Figure 8A) and Figure 8D) (showing the result of the experiment according to Figure 8B), as compared with Figure 9B) (showing the result of the experiment according to Figure 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 Figure 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:
[0083] Figures 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 Figures 8 and 9.
[0084] A standard spinning solution of 13% cellulose in NMMO was spun at 110°C through the spinneret configuration as described, and was led through an air gap with a length of around 20 mm.
[0085] 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. Figure 9A).
[0086] Both Figures 10 and Figures 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:
[0087] For the production of the staple fiber depicted in Figure 12, spinneret orifices having four holes each were employed. Each hole had a diameter of 100 µm. The distance from the center of one hole to its neighbouring hole was 500 µm. 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°C through the spinneret configuration as described, and was led through an air gap with a length of around 20 mm.
[0088] As apparent from Figure 12, the resulting staple fiber shows excellent uniform cross-sectional shape and has a remarkably reproducible hollow structure.
Example 4:
[0089] 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 Figures 8 and 9, respectively) with varying decitex were produced. The following table compares the fiber tenacities of the fibers obtained:
Table 1
| Spinneret configuration | Pulp employed | Decitex (dtex) | Fiber tenacity (conditioned state) cN/dtex | Fiber elongation (conditioned 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 sulfat pulp produced by Bahia Brasil. ** KZO3 is a TCF-bleached beech sulfite pulp produced by Lenzing AG. |
[0090] 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:
[0091] Lyocell staple fiber according to the present invention produced with a spinneret configuration as described with regard to example 1 and Figures 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 2:
| Fiber Type | Pulp employed | Decitex (dtex) | Flexural rigidity (mN mm2/tex2) |
| 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 spinneret with trilobal, holes | KZO3 | 6.2 | 0.41 |
| Modal fiber- produced from a spinneret with trilobal holes | KZO3 | 6.4 | 0.34 |
| Modal fiber - produced from a spinneret with trilobal, holes | KZO3 | 6.5 | 0.44 |
| Modal fiber-produced from a spinneret with | KZO3 | 6.6 | 0.35 |
| 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 trifilar - "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. |
[0092] The Modal fiber in the above example was produced according to the teaching of WO 2006/060835 (not pre-published).
[0093] 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 mm2/tex2 in all of the examples.
1. Process for the manufacture of a Lyocell staple fiber, 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,
said process being characterized in that 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.
2. Process according to claim 1, characterized in that all of said holes have a circular shape.
3. Process according to claim 2, characterized in that all of said holes have the same diameter.
4. Process according to claim 2, characterized in that at least one or more of said holes has/have a higher diameter than the rest of said
holes.
5. Process according to claim 4, characterized in that the ratio of the cross-sectional area of the hole(s) with the higher diameter to
the cross-sectional area of the hole(s) with a smaller diameter is from more than
1:1 to 16:1, preferably 1.6 to 1 to 2.7 to 1.
6. Process according to any one of claims 1 to 5, characterized in that 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.
7. Process according to claim 6, characterized in that 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.
8. Process according to any one of claims 1 to 7, characterized in that the diameter of said holes in said hole assembly is from 35 to 200 µm.
9. Process according to any one of claims 1 to 8, characterized in that the distance from the centre of one hole to the centre of the next adjacent hole
in said hole assembly is from 100 to 500 µm, preferably 150 to 250 µm.
10. Process according to claim 1, characterized in that at least one of said holes has a non-circular shape.
11. Process according to claim 10, characterized in that said non-circular shape is a multilobal, preferably trilobal, or triangular shape.
12. Lyocell staple fibre consisting of a plurality of cut filaments, obtainable by a process
according to any of claims 2 to 9, 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 and wherein all of said partially overlapped cross-sectional shapes are essentially
circular shapes.
13. Lyocell staple fiber according to claim 12, characterized in that said two or more partially overlapped circular shapes have essentially the same diameter.
14. Lyocell staple fiber according to claim 12, characterized in that one or more of said partially overlapped circular shapes has/have a higher diameter
than the rest of said overlapped circular shapes.
15. Lyocell staple fiber according to any of claims 12 to 14, characterized in that said overall cross-sectional shape is a bi-filar cross-sectional shape resulting
from notionally overlapping two essentially circular shapes.
16. Lyocell staple fiber according to any one of claims 12 to 14, characterized in that said overall cross-sectional shape is a tri-filar cross-sectional shape resulting
from notionally overlapping three essentially circular shapes.
17. Lyocell staple fiber according to claim 16, characterized in that said three overlapped circular shapes are arranged in a row.
18. Lyocell staple fiber according to claim 17, characterized in that said three overlapped circular shapes are arranged in the form of a triangle.
19. Lyocell staple fiber according to any one of claims 12 to 14, characterized in that said overall cross-sectional shape is a quadri-filar cross-sectional shape resulting
from notionally overlapping four essentially circular shapes.
20. Lyocell staple fiber according to claim 19, characterized in that said four overlapped circular shapes are arranged in a row.
21. Lyocell staple fiber according to claim 19, characterized in that said four overlapped circular shapes are arranged in the form of a square, a parallelogram,
or a rhombus.
22. Lyocell staple fiber according to claim 19, characterized in that 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.
23. Lyocell staple fiber according to any of claims 15 to 22, characterized in that said filaments exhibit a decitex of from 0.5 to 8 dtex, preferably 0.5 to 4 dtex.
24. Lyocell staple fiber according to any of claims 12 to 14, characterized in that 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.
25. Lyocell staple fiber according to any of claims 12 to 24, characterized in that essentially all of the cut filaments exhibit essentially the same overall cross-sectional
shape.
26. Lyocell staple fiber according to any claims 12 to 25, characterized in that said overall cross-sectional shape is hollow.
27. Lyocell staple fiber according to any of claims 12 to 26, characterized in that it exhibits a fibre tenacity in conditioned state which is higher by at least 15%,
preferably at least 20%, than the fibre 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.
28. Lyocell staple fiber according to any of claims 12 to 27, characterized in that it exhibits a decitex-related flexural rigidity of at least 0.5 mN.mm2/tex2, preferably more than 0.6 mN.mm2/tex2.
29. Use of Lyocell staple fiber according to any one of claims 12 to 28 for a product
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 fibre 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.
1. Verfahren zur Herstellung einer Lyocell-Stapelfaser, umfassend die folgenden Schritte:
- das Extrudieren einer Lösung von Cellulose, die in einem wässrigen tertiären Aminoxid gelöst ist, durch eine Spinndüse, die eine Mehrzahl von Spinndüsenöffnungen aufweist, wodurch Filamente gebildet werden
- das Leiten dieser Filamente über einen Luftspalt in ein Fällbad
- das Verstrecken der Filamente in diesem Luftspalt
- das Blasen von Luft auf die Filamente im Luftspalt
- das Ausfällen der Filamente im Fällbad
- das Zerschneiden der ausgefällten Filamente, um geschnittene Filamente zu bilden,
wobei- zumindest ein Teil dieser Spinndüsenöffnungen aus einer Gruppe von zwei oder mehr nebeneinanderliegenden Löchern besteht, so dass beim Extrudieren der Lösung durch die Löcher die aus diesen Löchern extrudierten Filamente teilweise verschmolzen werden, um ein einziges verschmolzenes Filament zu bilden,
wobei das Verfahren dadurch gekennzeichnet ist, dass die Luft, die auf die Filamente im Luftspalt geblasen wird,- im Falle einer Reihenanordnung der Löcher im Wesentlichen parallel zur Richtung der Reihe
- im Falle einer Dreiecksanordnung der Löcher im Wesentlichen parallel zur Richtung einer der Grundlinien des Dreiecks
- im Falle einer Quadratanordnung der Löcher im Wesentlichen parallel zur Richtung einer der Grundlinien des Quadrats
- im Falle einer anderen geometrischen Anordnung der Löcher im Wesentlichen parallel zur Richtung der Hauptorientierungsachse der Anordnung
auf die Filamente gerichtet wird.2. Verfahren gemäß Anspruch 1, dadurch gekennzeichnet, dass all diese Löcher eine kreisrunde Form haben.
3. Verfahren gemäß Anspruch 2, dadurch gekennzeichnet, dass all diese Löcher denselben Durchmesser haben.
4. Verfahren gemäß Anspruch 2, dadurch gekennzeichnet, dass zumindest eines oder mehrere dieser Löcher einen größeren Durchmesser hat bzw. haben
als der Rest der Löcher.
5. Verfahren gemäß Anspruch 4, dadurch gekennzeichnet, dass das Verhältnis der Querschnittsfläche des Lochs (der Löcher) mit dem größeren Durchmesser
zur Querschnittsfläche des Lochs (der Löcher) mit kleinerem Durchmesser von mehr als
1:1 bis 16:1, vorzugsweise von 1,6 zu 1 bis 2,7 zu 1, beträgt.
6. Verfahren gemäß einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass alle Spinndüsenöffnungen aus einer hinsichtlich der geometrischen Anordnung, der
Form und der Größe der Löcher identischen Gruppe von Löchern bestehen.
7. Verfahren gemäß Anspruch 6, dadurch gekennzeichnet, dass die Spinndüsenöffnungen in einer Mehrzahl von parallelen Reihen positioniert sind
und dass in jeder dieser Reihen alle Gruppen von Löchern im Wesentlichen parallel
zueinander ausgerichtet sind.
8. Verfahren gemäß einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass der Durchmesser der Löcher bei dieser Lochgruppe 35 bis 200 µm beträgt.
9. Verfahren gemäß einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass der Abstand vom Zentrum des einen Lochs zum Zentrum des nächsten benachbarten Lochs
bei der Lochgruppe 100 bis 500 µm, vorzugsweise 150 bis 250 µm, beträgt.
10. Verfahren gemäß Anspruch 1, dadurch gekennzeichnet, dass zumindest eines der Löcher eine nicht kreisrunde Form hat.
11. Verfahren gemäß Anspruch 10, dadurch gekennzeichnet, dass die nicht kreisrunde Form eine multilobale, vorzugsweise trilobale, oder dreieckige
Form ist.
12. Lyocell-Stapelfaser, bestehend aus einer Mehrzahl von geschnittenen Filamenten, erhältlich
durch ein Verfahren gemäß einem der Ansprüche 2 bis 9, wobei zumindest ein Teil dieser
geschnittenen Filamente eine Gesamtquerschnittsform aufweist, welche eine bi- oder
multifilare Querschnittsform ist, die sich aus zwei oder mehr, sich gedanklich teilweise
überlappenden Faserquerschnittsformen ergibt, und wobei alle der teilweise überlappten
Querschnittsformen im Wesentlichen kreisrunde Formen sind.
13. Lyocell-Stapelfaser gemäß Anspruch 12, dadurch gekennzeichnet, dass diese zwei oder mehr teilweise überlappten Kreisformen im Wesentlichen denselben
Durchmesser haben.
14. Lyocell-Stapelfaser gemäß Anspruch 12, dadurch gekennzeichnet, dass eine oder mehrere dieser teilweise überlappten Kreisformen einen größeren Durchmesser
hat bzw. haben als der Rest der überlappten Kreisformen.
15. Lyocell-Stapelfaser gemäß einem der Ansprüche 12 bis 14, dadurch gekennzeichnet, dass die Gesamtquerschnittsform eine bifilare Querschnittsform ist, die sich aus zwei,
sich gedanklich überlappenden, im Wesentlichen kreisrunden Formen ergibt.
16. Lyocell-Stapelfaser gemäß einem der Ansprüche 12 bis 14, dadurch gekennzeichnet, dass die Gesamtquerschnittsform eine trifilare Querschnittsform ist, die sich aus drei,
sich gedanklich überlappenden, im Wesentlichen kreisrunden Formen ergibt.
17. Lyocell-Stapelfaser gemäß Anspruch 16, dadurch gekennzeichnet, dass die drei überlappten Kreisformen in einer Reihe angeordnet sind.
18. Lyocell-Stapelfaser gemäß Anspruch 17, dadurch gekennzeichnet, dass die drei überlappten Kreisformen in Form eines Dreiecks angeordnet sind.
19. Lyocell-Stapelfaser gemäß einem der Ansprüche 12 bis 14, dadurch gekennzeichnet, dass die Gesamtquerschnittsform eine quadrifilare Querschnittsform ist, die sich aus vier,
sich gedanklich überlappenden, im Wesentlichen kreisrunden Formen ergibt.
20. Lyocell-Stapelfaser gemäß Anspruch 19, dadurch gekennzeichnet, dass die vier überlappten Kreisformen in einer Reihe angeordnet sind.
21. Lyocell-Stapelfaser gemäß Anspruch 19, dadurch gekennzeichnet, dass die vier überlappten Kreisformen in Form eines Quadrats, eines Parallelogramms oder
einer Raute angeordnet sind.
22. Lyocell-Stapelfaser gemäß Anspruch 19, dadurch gekennzeichnet, dass die vier überlappten Kreisformen in Form eines Dreiecks angeordnet sind, wobei eine
dieser Kreisformen das Zentrum des Dreiecks bildet.
23. Lyocell-Stapelfaser gemäß einem der Ansprüche 15 bis 22, dadurch gekennzeichnet, dass die Filamente einen Titer von 0,5 bis 8 dtex, vorzugsweise 0,5 bis 4 dtex, aufweisen.
24. Lyocell-Stapelfaser gemäß einem der Ansprüche 12 bis 14, dadurch gekennzeichnet, dass die Gesamtquerschnittsform eine multifilare Querschnittsform ist, die sich aus fünf
oder mehr, vorzugsweise fünf oder sieben, sich gedanklich überlappenden, im Wesentlichen
kreisrunden Formen ergibt.
25. Lyocell-Stapelfaser gemäß einem der Ansprüche 12 bis 24, dadurch gekennzeichnet, dass im Wesentlichen alle geschnittenen Filamente im Wesentlichen dieselbe Gesamtquerschnittsform
aufweisen.
26. Lyocell-Stapelfaser gemäß einem der Ansprüche 12 bis 25, dadurch gekennzeichnet, dass die Gesamtquerschnittsform hohl ist.
27. Lyocell-Stapelfaser gemäß einem der Ansprüche 12 bis 26, dadurch gekennzeichnet, dass sie im konditionierten Zustand eine Faserfestigkeit aufweist, die um zumindest 15%,
vorzugsweise zumindest 20%, höher als die Faserfestigkeit einer als Vergleich dienenden
Lyocell-Stapelfaser mit demselben Titer ist, wobei alle geschnittenen Filamente dieser
als Vergleich dienenden Lyocell-Stapelfaser einen im Wesentlichen runden Querschnitt
aufweisen.
28. Lyocell-Stapelfaser gemäß einem der Ansprüche 12 bis 27, dadurch gekennzeichnet, dass sie eine Titer-bezogene Biegesteifigkeit von zumindest 0,5 mN.mm2/tex2, vorzugsweise von mehr als 0,6 mN.mm2/tex2, aufweist.
29. Verwendung einer Lyocell-Stapelfaser gemäß einem der Ansprüche 12 bis 28 für ein Produkt,
ausgewählt aus der Gruppe, bestehend aus medizinischen Textilien, Hygienetextilien,
Haushaltstextilien, technischen und Bekleidungsanwendungen, wie z.B. Wundverbänden,
Laparotomie-Kompressen, Bettkissen, Tampons, Damenbinden, Wischtüchern, Inkontinenzprodukten,
Kissen, Schlafdecken, Handtüchern, Teppichen, Florgeweben, Damast, Satin, Isoliermaterialien,
Verstärkungsfasern für Polymere, Papier oder Beton, Textilartikeln wie z.B. gestrickten
oder gewebten Textilartikeln, Hemdenstoffen, Velours, Chinostoffen, Geweben mit baumwollartigem
Griff und daraus hergestellten Kleidungsstücken.
1. Procédé de fabrication d'une fibre coupée de lyocell, comprenant les étapes de
- extrusion d'une solution de cellulose dissoute dans un oxyde d'amine tertiaire aqueux à travers une filière présentant une pluralité d'orifices de filière de sorte que des filaments sont formés
- conduite desdits filaments par l'intermédiaire d'une couche d'air dans un bain de précipitation
- entraînement desdits filaments dans ladite couche d'air
- soufflage d'air sur lesdits filaments dans ladite couche d'air
- précipitation desdits filaments dans ledit bain de précipitation
- découpe desdits filaments précipités afin de former des filaments coupés,
dans lequel- au moins une partie desdits orifices de la filière est constituée d'un ensemble de deux trous ou plus étant situés de manière adjacente de sorte que lorsque la solution est extrudée à travers lesdits trous, les filaments extrudés desdits trous sont partiellement fusionnés pour former un filament fusionné,
ledit procédé étant caractérisé en ce que ledit air soufflé sur lesdits filaments dans la couche d'air est dirigé sur lesdits filaments- dans le cas d'un agencement par rangée desdits trous, sensiblement parallèle à la direction de ladite rangée
- dans le cas d'un agencement en triangle desdits trous, sensiblement parallèle à la direction de l'une des lignes de base dudit triangle
- dans le cas d'un agencement en carré desdits trous, sensiblement parallèle à la direction de l'une des lignes de base dudit carré
- dans le cas d'un autre agencement géométrique desdits trous, sensiblement parallèle à la direction de l'axe principal d'orientation dudit agencement.
2. Procédé selon la revendication 1, caractérisé en ce que lesdits trous ont tous une forme circulaire.
3. Procédé selon la revendication 2, caractérisé en ce que lesdits trous ont tous le même diamètre.
4. Procédé selon la revendication 2, caractérisé en ce qu'au moins un ou plusieurs desdits trous a/ont un diamètre supérieur au reste desdits
trous.
5. Procédé selon la revendication 4, caractérisé en ce que le rapport de l'aire en coupe transversale du(des) trou(s) avec le diamètre plus
élevé sur la surface en coupe transversale du(des) trou(s) avec un diamètre plus petit
est de plus de 1:1 à 16:1, de préférence de 1,6 à 1 jusqu'à 2,7 à 1.
6. Procédé selon l'une quelconque des revendications 1 à 5, caractérisé en ce que lesdits orifices de la filière sont tous constitués d'un ensemble identique de trous
en termes d'agencement géométrique, de forme et de taille desdits trous.
7. Procédé selon la revendication 6, caractérisé en ce que lesdits orifices de la filière sont positionnés en une pluralité de rangées parallèles
et en ce que, à l'intérieur de chacune desdites rangées, tous les ensembles de trous sont orientés
sensiblement parallèlement les uns aux autres.
8. Procédé selon l'une quelconque des revendications 1 à 7, caractérisé en ce que le diamètre desdits trous dans ledit ensemble de trous est de 35 à 200 µm.
9. Procédé selon l'une quelconque des revendications 1 à 8, caractérisé en ce que la distance du centre d'un trou au centre du trou adjacent suivant dans ledit ensemble
de trous est de 100 à 500 µm, de préférence 150 à 250 µm.
10. Procédé selon la revendication 1, caractérisé en ce qu'au moins l'un desdits trous a une forme non circulaire.
11. Procédé selon la revendication 10, caractérisé en ce que ladite forme non circulaire est une forme multilobée, de préférence trilobée, ou
triangulaire.
12. Fibre coupée de Lyocell constituée d'une pluralité de filaments coupés, pouvant être
obtenue par un procédé selon l'une quelconque des revendications 2 à 9, dans laquelle
au moins une partie desdits filaments coupés présente une forme générale en coupe
transversale qui est une forme bi ou multifilaire en coupe transversale résultant
de deux formes de fibres en coupe transversale ou plus se chevauchant théoriquement
partiellement et dans laquelle toutes lesdites formes en coupe transversale se chevauchant
partiellement sont sensiblement de formes circulaires.
13. Fibre coupée de Lyocell selon la revendication 12, caractérisée en ce que lesdites deux formes circulaires se chevauchant partiellement ou plus ont sensiblement
le même diamètre.
14. Fibre coupée de Lyocell selon la revendication 12, caractérisée en ce qu'une ou plusieurs desdites formes circulaires se chevauchant partiellement a/ont un
diamètre supérieur au reste desdites formes circulaires se chevauchant.
15. Fibre coupée de Lyocell selon l'une quelconque des revendications 12 à 14, caractérisée en ce que ladite forme générale en coupe transversale est une forme bi-filaire en coupe transversale,
résultant de deux formes sensiblement circulaires se chevauchant théoriquement.
16. Fibre coupée de Lyocell selon l'une quelconque des revendications 12 à 14, caractérisée en ce que ladite forme générale en coupe transversale est une forme tri-filaire en coupe transversale,
résultant de trois formes sensiblement circulaires se chevauchant théoriquement.
17. Fibre coupée de Lyocell selon la revendication 16, caractérisée en ce que lesdites trois formes circulaires se chevauchant sont agencées en une rangée.
18. Fibre coupée de Lyocell selon la revendication 17, caractérisée en ce que lesdites trois formes circulaires se chevauchant sont agencées sous la forme d'un
triangle.
19. Fibre coupée de Lyocell selon l'une quelconque des revendications 12 à 14, caractérisée en ce que ladite forme générale en coupe transversale est une forme quadri-filaire en coupe
transversale résultant de quatre formes sensiblement circulaires se chevauchant théoriquement.
20. Fibre coupée de Lyocell selon la revendication 19, caractérisée en ce que lesdites quatre formes circulaires se chevauchant sont agencées en une rangée.
21. Fibre coupée de Lyocell selon la revendication 19, caractérisée en ce que lesdites quatre formes circulaires se chevauchant sont agencées sous la forme d'un
carré, d'un parallélogramme, ou d'un losange.
22. Fibre coupée de Lyocell selon la revendication 19, caractérisée en ce que lesdites quatre formes circulaires se chevauchant sont agencées sous la forme d'un
triangle, avec l'une desdites formes circulaires formant le centre dudit triangle.
23. Fibre coupée de Lyocell selon l'une quelconque des revendications 15 à 22, caractérisée en ce que lesdits filaments présentent un décitex de 0,5 à 8 dtex, de préférence 0,5 à 4 dtex.
24. Fibre coupée de Lyocell selon l'une quelconque des revendications 12 à 14, caractérisée en ce que ladite forme générale en coupe transversale est une forme multifilaire en coupe résultant
de cinq ou plus, de préférence cinq ou sept formes sensiblement circulaires se chevauchant
théoriquement.
25. Fibre coupée de Lyocell selon l'une quelconque des revendications 12 à 24, caractérisée en ce que sensiblement tous les filaments coupés présentent sensiblement la même forme générale
en coupe transversale.
26. Fibre coupée de Lyocell selon l'une quelconque des revendications 12 à 25, caractérisée en ce que ladite forme générale en coupe transversale est creuse.
27. Fibre coupée de Lyocell selon l'une quelconque des revendications 12 à 26, caractérisée en ce qu'elle présente une ténacité de fibre à l'état conditionné, qui est supérieure d'au
moins 15 %, de préférence d'au moins 20 %, à la ténacité de fibre d'une fibre coupée
de Lyocell de comparaison du même décitex, dans laquelle tous les filaments coupés
de ladite fibre coupée de Lyocell de comparaison présentent une coupe transversale
sensiblement ronde.
28. Fibre coupée de Lyocell selon l'une quelconque des revendications 12 à 27, caractérisée en ce qu'elle présente une rigidité à la flexion reliée au décitex d'au moins 0,5 mN.mm2/tex2, de préférence plus de 0,6 mN.mm2/tex2
29. Utilisation de fibre coupée de Lyocell selon l'une quelconque des revendications 12
à 28 pour un produit choisi dans le groupe constitué par des applications médicales,
d'hygiène, de textiles ménagers, techniques et vestimentaires, telles que des pansements,
des compresses pour laparotomie, des coussins, des tampons, des serviettes hygiéniques,
des lingettes, des produits d'incontinence, des oreillers, des couettes, des serviettes,
des tapis, des tissus à poils, des damas, du satin, des matériaux d'isolation, des
fibres de renfort pour les polymères, du papier ou du béton, des articles textiles,
tels que des articles textiles tricotés ou tissés, des chemises, du velours, des chinos,
des tissus faits main analogues au coton et des vêtements faits avec ceux-ci.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
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