U.S. patent application number 17/111005 was filed with the patent office on 2021-03-25 for cellulose fiber.
The applicant listed for this patent is LENZING AKTIENGESELLSCHAFT. Invention is credited to Heinrich Firgo, Karl Michael Hainbucher, Hartmut Ruf, Christoph Schrempf, Kurt Christian Schuster.
Application Number | 20210087714 17/111005 |
Document ID | / |
Family ID | 1000005253436 |
Filed Date | 2021-03-25 |
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United States Patent
Application |
20210087714 |
Kind Code |
A1 |
Schrempf; Christoph ; et
al. |
March 25, 2021 |
CELLULOSE FIBER
Abstract
The present invention relates to a fiber of the Lyocell type
which has a titer of from 0.8 dtex to 3.3 dtex and is characterized
by the following relationships: Holler factor F2.gtoreq.1,
preferably .gtoreq.2 Holler factor F1.gtoreq.-0.6 Holler factor
F2.ltoreq.6 and Holler factor F2 minus 4.5*Holler factor
F1.gtoreq.1, preferably .gtoreq.3. The fiber according to the
invention displays a specific combination of properties with regard
to the Holler factors, the flexibility and the abrasion resistance
within a planar assembly. Hence, the fiber shows a behavior more
similar to viscose and can be processed in the textile chain
according to viscose standard methods.
Inventors: |
Schrempf; Christoph; (A-4701
Bad Schallerbach, AT) ; Schuster; Kurt Christian;
(A-4840 Vocklabruck, AT) ; Ruf; Hartmut; (A-4861
Schorfling, AT) ; Firgo; Heinrich; (A-4840
Vocklabruck, AT) ; Hainbucher; Karl Michael; (A-4861
Schorfling, AT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LENZING AKTIENGESELLSCHAFT |
A-4860 Lenzing |
|
AT |
|
|
Family ID: |
1000005253436 |
Appl. No.: |
17/111005 |
Filed: |
December 3, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15108713 |
Jun 28, 2016 |
10883196 |
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PCT/EP2014/079043 |
Dec 22, 2014 |
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17111005 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D01F 2/00 20130101 |
International
Class: |
D01F 2/00 20060101
D01F002/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 3, 2014 |
EP |
14150132.0 |
Claims
1) A cellulosic fiber of the Lyocell type which has a titer of from
0.8 dtex to 3.3 dtex and is characterized by the following
relationships: Holler factor F2.gtoreq.1, preferably .gtoreq.2
Holler factor F1.gtoreq.-0.6 Holler factor F2.ltoreq.6 and Holler
factor F2 minus 4.5*Holler factor F1.gtoreq.1, preferably
.gtoreq.3.
2) The fiber according to claim 1, characterized by a wet abrasion
resistance amounting to between 300 and 5000 revolutions.
3) The fiber according to claim 1 or 2, characterized by a
flexibility of between 0.55 and 1.00.
4) The fiber according to any of the preceding claims, wherein a
single jersey 150 g/m2 produced from a ring yarn Nm 50/1 of said
fiber exhibits an abrasion resistance according to Martindale of
between 30 000 and 60 000 tours up to the point of hole
formation.
5) The fiber according to any of the preceding claims,
characterized in that it is produced according to the amine oxide
process.
6) The fiber according to any of the preceding claims,
characterized in that it is produced from a mixture of at least two
different pulps.
7) A fiber bundle comprising a plurality of fibers according to any
of the preceding claims.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to a cellulosic fiber of the
Lyocell type.
[0002] In consequence of the environmental problems associated with
the known viscose process for the production of cellulosic fibers,
intense efforts have been made in recent decades to provide
alternative and more environmentally friendly methods. A
particularly interesting possibility which thereby has arisen in
recent years is to dissolve cellulose in an organic solvent without
a derivative being formed and to extrude moulded bodies from said
solution. Fibers spun from such solutions have received the generic
name Lyocell from BISFA (The International Bureau for the
Standardization of man-made fibers), wherein an organic solvent is
understood to be a mixture of an organic chemical and water.
[0003] Furthermore, such fibers are also known by the term
"solvent-spun fibers".
[0004] It has turned out that in particular a mixture of a tertiary
amine oxide and water is perfectly suitable as an organic solvent
for the production of Lyocell fibers and other moulded bodies,
respectively. Thereby, N-methylmorpholine-N-oxide (NMMO) is
predominantly used as the amine oxide. Other suitable amine oxides
are disclosed in EP-A 553 070.
[0005] In EP 0 356 419 A, a technical implementation of the method
of producing a solution of a pulp in an amine oxide is described.
In doing so, a suspension of the crushed pulp is conveyed in an
aqueous tertiary amine oxide in the form of a thin layer across a
heating surface, water is evaporated and, thereby, a spinnable
cellulose solution is produced.
[0006] A method of spinning cellulose solutions in amine oxides is
known from U.S. Pat. No. 4,246,221. According to said method,
filaments extruded from a spinneret are guided through an air gap,
drawn therein and, subsequently, the cellulose is precipitated in
an aqueous spinning bath. The method is known as a "dry/wet
spinning process" or also as an "air-gap spinning process".
[0007] The entire method of producing fibers from solutions of
cellulose in a tertiary amine oxide is referred to in the following
as an "amine oxide process", with the abbreviation "NMMO" denoting
hereinafter all tertiary amine oxides which are able to dissolve
cellulose. Fibers produced according to the amine oxide process are
characterized by a high fiber strength in the conditioned state as
well as in the wet state, a high wet modulus and a high loop
strength.
[0008] The conditions within the air gap such as temperature,
humidity, cooling rate of the filaments as well as draft dynamics
are of great significance for the properties of the resulting
fibers (see, in this connection, the publication by Volker Simon in
"Transactions of the American Society of Mechanical Engineers
(ASME) 118 (1996) No. February, p. 246-249").
[0009] Technical embodiments of the spinning process have been
described in numerous documents:
[0010] WO 93/19230 describes a method wherein the extruded
filaments are cooled just beneath the nozzle by being blasted with
air. WO 94/28218 describes a nozzle design and a blowing method. WO
95/01470 claims a laminar flow of the cooling gas stream described
in WO 93/19230. WO 95/04173 describes a further technical
implementation of blowing. In WO 96/17118, the moisture content of
the blowing air is defined. In WO 01/68958, the blowing air stream
is directed downwards toward the extruded filaments at an angle of
from 0.degree. to 45.degree.. WO 03/014436 describes a blowing
device comprising a suction of the blowing air. WO 03/057951 claims
the shielding of part of the air gap from the blowing air. In WO
03/057952, a turbulent gas stream for cooling the filaments is
described. WO 05/116309 likewise describes the shielding of part of
the air gap from the blowing air.
[0011] The fibers/filaments obtained according to the air-gap
spinning process differ in structural terms from known viscose
fibers. While the crystalline orientation is approximately at the
same high level both in viscose fibers and in Lyocell fibers (a
largely parallel arrangement of the cellulose chains located in the
structured areas of the fiber relative to the fiber axis),
considerable differences exist in the amorphous orientation (a
higher parallelism of the random portions in Lyocell fibers).
[0012] The particularities of the Lyocell fiber such as a high
crystallinity, long and thin crystallites and a high amorphous
orientation prevent an adequate bond of the crystallites
transversely to the fiber axis. In the wet state, the swelling of
the fibers additionally reduces the bonding forces transversely to
the fiber axis and thus leads to the separation of fiber fragments
under mechanical strain. This behavior is referred to as wet
fibrillation and causes quality losses in the form of greying and
hairiness in the final textile product.
[0013] Surveys of the state of research in this field are provided
by the works of Josef Schurz, Jurgen Lenz: "Investigations on the
structure of regenerated cellulose fibers" in Macromolecular
Symposia, Volume 83, Issue 1, pages 273-289, May 1994, and Fink
H-P, Weigel P, Purz H-J, Ganster J "Structure formation of
regenerated cellulose materials from NMMO-solutions" Prog. Polym.
Sci. 2001 (26) p. 1473-1524.
[0014] Previous efforts to improve the wet-fibrillation resistance
of Lyocell fibers were aimed in two directions:
[0015] varying the manufacturing conditions, or
[0016] introducing a step of chemical cross-linking during the
production process
[0017] However, it is hardly possible to evaluate the success of
the measures of reducing fibrillation which have been described in
each case. There is no standardized method of measuring the
fibrillation behavior, and all the methods applied in the patent
literature are proprietary.
[0018] The second procedure, chemical cross-linking, is associated
with a number of drawbacks such as
[0019] additional chemicals/costs of chemicals/waste water problems
during the production of the fiber
[0020] environmental pollution during the production of the
cross-linking chemicals
[0021] inadequate hydrolysis stability of cross-linking under the
conditions of textile processing.
[0022] Examples of the procedure of chemical cross-linking are
described in EP 0 53 977 A, EP 0 665 904 A and EP 0 943 027 A,
respectively.
[0023] Numerous documents have been published with regard to the
first procedure, varying the manufacturing conditions. However, the
described methods have either brought about only a slight
improvement in the fibrillation behavior, which has not been
reflected in a lasting improvement of processability, or the
methods have failed to be feasible on a large scale as a result of
the costs/technical expenditures.
[0024] In SU 1,224,362, a dope is spun from a single pulp into a
bath containing NMMO in amyl alcohol or isopropanol, respectively.
WO 92/14871 claims a fiber with a reduced fibrillation,
characterized in that the pH of the spinning bath and of subsequent
washing baths is below 8.5. No details are given about the type of
the pulp or the spinning conditions.
[0025] WO 94/19405 describes a method wherein a pulp mixture is
used. However, no reference is made to the tendency toward
fibrillation of the fibers which have been spun.
[0026] WO 95/02082 describes a combination of process parameters,
illustrated in a mathematical expression, for the production of a
fiber with a low tendency toward fibrillation. Said process
parameters are the diameter of the spinning hole, the output of
spinning mass, the titer of the filaments, the width of the air gap
and the humidity in the air gap. The pulp used is not described in
detail, the spinning temperature is only 115.degree. C.
[0027] In WO 95/16063, the extruded filaments are contacted in the
spinning bath or in the aftertreatment baths, respectively, with a
surfactant in a dissolved form. The type of the pulp used is not
specified, the spinning temperature is 115.degree. C.
[0028] WO 96/07779 uses an organic solvent, preferably polyethylene
glycol, as a spinning bath. No details are given about the pulp
used or the textile-mechanical properties of the obtained fibers.
110.degree. C. is indicated as the spinning temperature.
[0029] In WO 96/07777, the extruded filaments are contacted in the
air gap with an aliphatic alcohol provided in a gaseous form. The
type of the pulp used is not specified, the spinning temperature is
115.degree. C.
[0030] WO 96/20301 describes a method wherein the moulded solution
is guided consecutively through at least two precipitation media,
with a slower coagulation of the cellulose occurring in the first
precipitation medium as compared to the latter precipitation
medium. In the examples, a higher alcohol is preferably used as the
first precipitation medium. The pulp used is not indicated, the
spinning temperature amounts to 115.degree. C.
[0031] WO 96/21758 describes a method wherein the moulded solution
is blasted in the air gap in an upper zone with air having a higher
moisture content and in a lower zone with air having a lower
moisture content. Single pulps of various degrees of polymerization
are used as pulps, the spinning temperature amounts to 115.degree.
C.
[0032] EP 0 853 146 describes a two-stage method wherein the dwell
time of the fibers in the first precipitation stage is adjusted
such that merely the stickiness of the surface of the solution
moulded into fibers is prevented and the fibers are coagulated
without tension in a later precipitation stage. In the examples,
the spinning temperature amounts to 109-112.degree. C.
[0033] In WO 97/23669, spinning takes place into a spinning bath
having a content of NMMO of more than 60%. A single pulp is
used.
[0034] In WO 97/35054, a combination of parameters for obtaining a
fiber low in fibrillation is described, namely the concentration of
the dope, the draft in the air gap as well as the diameter of the
nozzle hole. A single pulp is used, the spinning temperature ranges
from 80 to 120.degree. C.
[0035] In WO 97/38153, a combination of parameters for obtaining a
fiber low in fibrillation is likewise described, namely the length
of the air gap, the spinning rate, the dwell time in the air gap,
the speed of the blowing air in the air gap, the moisture content
of the blowing air as well as the product of the dwell time in the
air gap times the moisture content of the blowing air. A single
pulp is used as the pulp.
[0036] In WO 97/36028, the fibers are treated with a solution of
40-80% NMMO, optionally with an additive being added, upon leaving
the precipitation bath.
[0037] In WO 97/36029, the fibers are treated with a solution of
zinc chloride upon leaving the precipitation bath.
[0038] In WO 97/46745, the fibers are treated with a solution of
NaOH upon leaving the precipitation bath.
[0039] In WO 98/02602, the fibers are treated with a solution of
NaOH upon leaving the precipitation bath in a relaxed state.
[0040] In WO 98/06745, a pulp mixture is used which is obtained by
mixing solutions of pulps of different degrees of polymerization.
No details are given with regard to the spinning temperature.
[0041] In WO 98/09009, the addition of additives (polyalkylenes,
polyethylene glycols, polyacrylates) to the spinning mass is
described. A single pulp is used as the pulp.
[0042] In WO 98/22642, a pulp mixture having a low degree of
polymerization is used. The spinning temperature amounts to
110-120.degree. C.
[0043] Also in WO 98/30740, a pulp mixture is used, the spinning
mass is spun according to a centrifugal spinning process. The
spinning temperature amounts to 80-120.degree. C.
[0044] In WO 98/58103, details about the molecular weight
distribution of the pulp in a spinning mass from a pulp mixture are
indicated, which lead to stable spinning. However, no reference is
made to the fibrillation behavior of the obtained
fibers/filaments.
[0045] In DE 19753190, the fibers are treated with a concentrated
NMMO solution upon leaving the precipitation bath.
[0046] In GB 2337990, a co-solvent is used for dissolving the
single pulp. The nascent solution is spun at 60-70.degree. C.
[0047] In U.S. Pat. No. 6,471,727, a spinning mass from a single
pulp with a high content of hemicellulose and lignin is processed
according to a dry/wet or meltblown spinning process,
respectively.
[0048] In WO 01/81663, a spinneret is described in which the
spinning capillary is directly heated close to the outlet
cross-section. Said measure is supposed to reduce the tendency
toward fibrillation of Lyocell fibers, however, no test conditions
are specified for this.
[0049] WO 01/90451 describes a spinning method characterized by a
mathematical relationship including the heat flux density in the
air gap and the ratio of length to diameter of the extrusion
channel. Fibers spun according to the invention are proposed to
display a lower tendency toward fibrillation, however, no further
details are given in this connection.
[0050] In U.S. Pat. No. 6,773,648, a meltblown process for the
production of a fibrillation-reduced fiber is made public. Due to
their irregular titers, meltblown fibers are unsuitable for textile
use.
[0051] In DE 10203093, a fiber with a low fibrillation is produced
by spinning two dopes of different cellulose concentrations from a
single pulp from a biocomponent nozzle. No example is given.
[0052] In DE 10304655, polyvinyl alcohol is added to the NMMO in
order to improve the quality of the solution. The conditions for
spinning the claimed less fibrillating fiber are not indicated.
[0053] The specific structure of the Lyocell fiber leads, on the
one hand, to excellent textile-mechanical properties such as a high
strength in both the dry and wet states as well as to a very good
dimensional stability of the planar assemblies produced therefrom
and, on the other hand, to little flexibility (high brittleness) of
the fibers, which manifests itself in a decrease in the abrasion
resistance in comparison to viscose fibers within the planar
assembly.
[0054] The term flexibility (compliance) is defined, according to
Hooke's Law, as the quotient from the elongation of the test body
and the load causing the elongation. Increasing the flexibility of
Lyocell fibers is the object of a number of publications:
[0055] A flexible Lyocell fiber is described in EP 0 686 712. The
patent claims a fiber with a reduced NMR degree of order, obtained
by adding nitrogenous substances such as urea, caprolactam or
aminopropanol to the polymer solution or into the precipitation
bath, respectively. However, a fiber with a very low wet strength
is obtained; thus, the fiber differs distinctly from the fibers
according to the invention as described below.
[0056] In WO 97/25462, a method for the production of a flexible
and fibrillation-reduced fiber is described, wherein, after the
precipitation bath, the moulded fiber is guided through a washing
and aftertreatment bath containing an aliphatic alcohol, in
addition, optionally, with an additive of sodium hydroxide. The
properties of the obtained fibers are described only very
insufficiently. In particular data about the dry and wet strengths
are missing, which would allow classification in the "Holler
chart", as described in further detail below.
[0057] It may be said, however, that, in the examples of the
present application, the fiber shows considerable differences in a
comparison of the fiber elongations indicated in said document with
the corresponding data of the fibers according to the invention and
that, due to the low values of elongation as indicated in said
document, the flexibility of the fiber cannot be very high
according to the above-mentioned definition of flexibility. The
improvement in the fibrillation behavior as mentioned in the text
of the document is not confirmed by any data whatsoever.
[0058] Documents EP 1 433 881, EP 1 493 753, EP 1 493 850, EP 1 841
905, EP 2 097 563 and EP 2 292 815 describe fibers and filaments,
respectively, preferably for the application tyre cord, produced by
adding polyvinyl alcohol to the NMMO/dope. The fibers/filaments are
characterized by high strength, but little elongation. Accordingly,
their flexibility can only be minor according to the
above-mentioned definition.
[0059] Further publications which indicate that, by adding
additives to the spinning mass, influence can be exerted on the
fibrillation behavior and/or the flexibility of the fiber, are
[0060] Chanzy H, Paillet m, Hagege R "Spinning of cellulose from
N-methylmorpholine N-oxide in the presence of additives" Polymer
1990, 31, p 400-5 [0061] Weigel P, Gensrich J, Fink H-P
"Strukturbildung Cellulosefasem aus Aminoxidlosungen" Lenzinger
Berichte 1994; 74(9), p 31-6 and [0062] Mortimer S A, Peguy A A
"Methods for reducing the tendency of lyocell fibers to fibrillate"
J. appl. Polym. Sci. 1996, 60, p 305-16.
[0063] WO 2014/029748 (not pre-published) discloses the manufacture
of solvent-spun cellulosic fibers, especially from solutions in
ionic liquids. Further state of the art in this regard is known
from DE 10 2011 119 840 A1, AT 506 268 A1, U.S. Pat. No. 6,153,136,
CN 102477591A, WO 2006/000197, EP 1 657 258 A1, US 2010/0256352 A1,
WO 2011/048608 A2, JP 2004/159231 A and CN 101285213 A.
[0064] The invention of viscose fibers (Cross and Bevan 1892, GB
8700) occurred more than a hundred years ago. Despite weaknesses in
the production (environmental problems) and the properties (poor
washing behavior of the standard type), more than one million tons
of said fiber type is produced each year.
[0065] The further development of the old process after the second
world war (polynosic and modal fibers) resulted in fibers with a
better washing behavior and a higher dimensional stability, but was
unable to change the intrinsic properties of the method
(environmental relevance as well as, due to the large number of
process steps, an extremely complicated method).
[0066] Conversely, it became apparent during the development of the
new fiber type "Lyocell" that, due to its varying structure, the
fiber places special demands on the processing conditions and,
thus, the established methods of processing a viscose or modal
fiber cannot be applied in the textile chain. Special machines and
processing adjustments which are adapted to the fiber are required
especially for dyeing and wet finishing. Today, more than 20 years
after the Lyocell fiber was placed on the market, this is still
regarded as a disadvantage.
[0067] Now it would be desirable to impart particular properties of
the viscose fiber such as
[0068] a lower tendency toward fibrillation in the wet state
[0069] higher flexibility (less brittleness)
to the Lyocell fiber while maintaining the excellent properties of
the Lyocell fiber (such as, e.g., a high wet strength, a high wet
modulus and, hence, a washability and a dimensional stability
which, in comparison to viscose fibers, are substantially
improved).
[0070] It is thus an object of the present invention to provide a
Lyocell fiber with properties more similar to viscose by means of
which processing of the fiber according to the well-known and
established methods of viscose processing is rendered possible.
[0071] The change in properties should be achieved solely by
choosing suitable process parameters for the production of the
fiber, without having to fall back on chemicals extraneous to the
process as additives to either the spinning mass, the spinning bath
or during the aftertreatment. Every additional chemical in the
system, be it as an additive to the spinning mass or to the
spinning bath, necessitates increased efforts for the recovery and
constitutes a cost factor.
[0072] The object of the present invention is achieved by a
cellulosic fiber of the Lyocell type which has a titer of from 0.8
dtex to 3.3 dtex and is characterized by the following
relationships:
[0073] Holler factor F2.gtoreq.1, preferably .gtoreq.2
[0074] Holler factor F1.gtoreq.-0.6
[0075] Holler factor F2.ltoreq.6 and
[0076] Holler factor F2 minus 4.5*Holler factor F1.gtoreq.1,
preferably .gtoreq.3.
SHORT DESCRIPTION OF THE FIGURES
[0077] FIG. 1 shows a Holler chart of commercially available fibers
from regenerated cellulose prior to the development of the Lyocell
fiber.
[0078] FIG. 2 shows the area in the Holler chart in which the
fibers according to the invention are located.
[0079] FIG. 3 shows a Holler chart in which the fiber according to
the invention is contrasted to a common Lyocell fiber.
DETAILED DESCRIPTION OF THE INVENTION
[0080] In the following, the new Lyocell fibers according to the
invention are described by reference to the so-called "Holler
factors" F1 and F2 and are distinguished from known cellulosic
man-made fibers of the prior art.
[0081] While the basic chemical structure of man-made cellulosic
fibers such as, e.g., viscose fibers, but also of Lyocell fibers,
is essentially the same (cellulose), the fibers differ in factors
such as, e.g., the crystallinity or also the orientation in
particular of amorphous areas. It is difficult to quantitatively
distinguish those factors from each other.
[0082] It is also apparent to a person skilled in the art that a
Lyocell fiber differs, for example, from a viscose fiber in
textile-mechanical parameters (such as, e.g., strength values), but
also in properties which can be defined less clearly, e.g., the
textile "grip". Likewise, there are considerable differences
between the different types of cellulose fibers produced according
to the viscose process such as, e.g., a (standard) viscose fiber, a
modal fiber or a polynosic fiber.
[0083] In the essay by R. Holler "Neue Methode zur
Charakterisierung von Fasem aus Regeneratcellulose" Melliand
Textilberichte 1984 (65) p. 573-4, a clear differentiation between
the different fiber types made of regenerated cellulose known at
the time, i.e., the fibers produced according to the viscose
process, could be presented on the basis of quantitative
features.
[0084] According to this suggestion the complexity of the
comparison of a greater number of fiber properties could be
simplified significantly by way of formation of few parameters
splitting fibers into groups of similar properties and by factor
analysis. Factor analysis is a multivariate statistical method
which makes it possible to reduce a group of correlated features to
a smaller number of uncorrelated factors.
[0085] The textile-mechanical properties used by Holler for factor
analysis were the maximum tensile force conditioned (FFk) and wet
(FFn), the maximum tensile force elongation conditioned (FDk) and
wet (FDn), the wet modulus (NM), the loop strength conditioned
(SFk) as well as the knot strength conditioned (KFk).
[0086] All those measurands as well as their determination are
known to a person skilled in the art, see, in particular, BISFA
regulation "Testing methods viscose, modal, lyocell and acetate
staple fibers and tows" Edition 2004 Chapters 6 and 7, and will be
described in further detail below.
[0087] In the fiber collective available to Holler, 87% to 92% of
the variance between the samples could be detected by merely two
factors (see FIG. 1). Those two factors are calculated as
follows:
Holler factor
F1=-1.109+0.03992.times.FFk-0.06502.times.FDk+0.04634.times.FFn-0.04048.t-
imes.FDn+0.08936.times.NM+0.02748.times.SFk+0.02559.times.KFk
Holler factor
F2=-7.070+0.02771.times.FFk+0.04335.times.FDk+0.02541FFn+0.03885FDn-0.015-
42.times.NM+0.2891.times.SFk+0.1640.times.KFk.
[0088] As can be seen in FIG. 1, a clear differentiation between
the different fiber types could be illustrated by way of this
analysis--drawn up on the basis of clearly measurable
parameters.
[0089] FIG. 1 shows in the coordinate system of Holler factors F1
and F2 the fiber collective made up of 70 samples of commercially
available fibers of regenerated cellulose which has been examined
by Holler. Along factor F1, it is possible to identify the division
into (standard) viscose fibers and modal fibers, which are also
listed by BISFA as different fiber types (although they are
produced according to the same basic method, namely the viscose
process). To the left of the ordinate, the region of (standard)
viscose fibers is shown (designated as "V" in FIG. 1). Essentially
to the right of the ordinate the region of modal fibers is shown,
which are further structured in two sub-groups, i.e. fibers of the
HWM-type ("HWM"--high wet modulus) and fibers of the polynosic type
("PN"). In addition, a (dashed) boundary is plotted in the graph,
beyond which none of the fibers made of regenerated cellulose and
examined at the time were located. However, at the time of this
publication, Lyocell fibers were still in the trial stage and not
commercially available.
[0090] Lyocell fibers which currently are commercially available
have Holler F1 values of 2 to 3 and F2 values of 2 to 8. In the
"Holler chart" according to FIG. 1, such fibers would therefore be
located beyond the above-mentioned boundary, from which the
considerable difference between the fibers of the viscose group and
the Lyocell fibers is apparent already purely visually.
[0091] The fiber according to the invention is now located in an
area of the Holler chart which can be illustrated by a square.
[0092] The sides of the square correspond to the following values
or relationships, respectively:
[0093] Lower boundary F2=1
[0094] Left-hand boundary F1=-0.6
[0095] Upper boundary F2=6
[0096] Right-hand boundary defined via the relationship:
[0097] Holler factor F2 minus 4.5*Holler factor F1.gtoreq.1,
preferably .gtoreq.3
[0098] The arrangement of the Lyocell fiber according to the
invention in the Holler chart resulting from said relation is shown
in FIG. 2. Loosely speaking, the fiber according to the invention
thus occupies in the Holler chart the space above the abscissa and
around the ordinate as well as to the left thereof and is clearly
distinguished from Lyocell fibers which are currently commercially
available and, in the Holler chart, are located, loosely speaking,
(considerably) to the right of the ordinate.
[0099] Conversely, the Lyocell fiber according to the invention is
located in the Holler chart close to the area of the (standard)
viscose. Actually, it has been shown that the Lyocell fiber
according to the invention has, with regard to its processability,
properties which are by far "more similar to viscose" than those of
Lyocell fibers which are currently commercially common.
[0100] In textile practice, these "more viscose-like" properties
lead to the following property changes:
[0101] The fiber according to the invention can be dyed as a planar
assembly like viscose in a strand (conventional Lyocell fibers are
only suitable for open-width dyeing).
[0102] Planar assemblies (such as knitted fabrics) made of the
fiber according to the invention, which have not been subjected to
high-grade finishing with a resin finish, will keep an unchanged
fabric appearance for a longer time when being washed.
[0103] Planar assemblies made of the fiber according to the
invention exhibit an abrasion resistance similar to planar
assemblies made of viscose and hence display an improvement by the
double in comparison to conventional Lyocell fibers.
[0104] However, the fiber according to the invention retains during
washing processes the high dimensional stability which is
characteristic of the Lyocell fiber.
[0105] Although the areas of the fiber according to the invention
and of (standard) viscose fibers as well as, partially, of modal
fibers overlap in the Holler chart, the fiber types can, however,
clearly be differentiated from each other based on basic
differences in the manufacturing process, since the fiber according
to the invention can be analytically distinguished unambiguously
from fibers produced according to the viscose process such as
(standard) viscose fibers and modal fibers:
[0106] A residual amount of solvent associated to the fiber type
Lyocell is detectable (in particular residues of NMMO in case of
fibers produced according to the amine oxide process).
[0107] Unlike a fiber produced according to the viscose process,
the fiber contains no sulphur.
[0108] According to the method described below, the wet abrasion
behavior of the fiber according to the invention ranges between 300
and 5000 revolutions up to the point of fiber breakage, preferably
between 500 and 3000 revolutions.
[0109] The flexibility (i.e., the quotient FDk/FFk) of the fiber
according to the invention preferably ranges between 0.55 and 1.00,
preferably between 0.65 and 1.00.
[0110] It has been shown that the dry abrasion according to
Martindale of a single jersey 150 g/m.sup.2 made of a ring yarn Nm
50/1 of the fiber according to the invention may range between 30
000 and 60 000 tours up to the point of hole formation.
[0111] The fiber according to the invention is preferably
characterized in that it is produced according to the amine oxide
process.
[0112] The fiber according to the invention is preferably provided
as a staple fiber, i.e., as cut fibers.
[0113] The property change according to the invention of Lyocell
fibers toward a Lyocell fiber similar to viscose and hence the
repositioning of the fiber data in the Holler chart is achieved,
according to the present invention, by carefully adjusting the raw
material and the process conditions:
1) Pulp
[0114] A defined molecular weight distribution of the raw material
used is required for the production of the fiber according to the
invention. This is achieved in particular by mixing two or more
single pulps. Accordingly, the fiber according to the invention is
preferably characterized in that it is produced from a mixture of
at least two different pulps.
[0115] The molecular weight distribution is characterized by the
following parameters:
[0116] a) The amount of celluloses or accompanying substances of
cellulose (polymeric pentosans and hexosans such as xylan,
glucomannan, low-molecular beta-1,4-glucan) with a degree of
polymerization of less than 50 is below 2% (based on the pulp
mixture), preferably below 1.5% (determination of the molecular
weight distribution with GPC/SEC by MALLS detection in DMAC/LiCl,
Bohm, R., A. Potthast, et al. (2004). "A novel diazo reagent for
fluorescence labeling of carboxyl groups in pulp." Lenzinger
Berichte 83: 84-91).
[0117] b) An amount of 70% to 95% of the pulp mixture has a
limiting viscosity number ranging from 250 to 500 ml/g, preferably
from 390 to 420 ml/g (measured according to SCAN-CM 15:99), in the
following referred to as the "low-molecular component".
[0118] c) An amount of 5% to 30% of the pulp mixture has a limiting
viscosity number of from 1000 to 2500 ml/g, preferably of 1500-2100
ml/g, in the following referred to as the "high-molecular
component".
[0119] d) Preferably, the amount of the low-molecular component is
70-75%, if the high-molecular component has a limiting viscosity
number of 1000-1800 ml/g, and, respectively, 70-95%, if the
high-molecular component has a limiting viscosity number of
>2000 ml/g.
[0120] e) Furthermore, the purity of the pulps used is important:
The purity is defined as the mean value of alkali resistances R10
and R18 according to DIN 54355 (1977), i.e. the determination of
the resistance of pulp against caustic soda (alkali resistance).
Said value approximately corresponds to the content of alpha
cellulose according to TAPPI T 203 CM-99.
[0121] The purity of the low-molecular component is >91%,
preferably >94%, the purity of the high-molecular component is
>91%, preferably >96%.
[0122] It has been shown that, in particular by using high-purity
pulps such as cotton linter pulps, it is possible more easily to
produce fibers displaying the properties according to the
invention.
[0123] Furthermore, it has been shown that pulps made from
reclaimed cotton textiles ("reclaimed cotton fibers"--RCF) are
suitable for the manufacture of the fibers according to the
invention. Such pulps can be produced according to the teaching of
the publication "Process for pretreating reclaimed cotton fibers to
be used in the production of moulded bodies from regenerated
cellulose" (Research Disclosure, www.researchdisclosure.com,
database number 609040, published digitally Dec. 11, 2014).
2) Spinning Conditions
[0124] In addition to choosing the appropriate pulp composition,
the spinning conditions for producing the fiber according to the
invention are of particular importance:
[0125] i) The throughput of spinning mass should range between 0.01
and 0.05 g/nozzle hole/min, preferably between 0.015 and 0.025
g/nozzle hole/min.
[0126] ii) Air gap length: The procedure of producing the fiber
according to the invention differs from the prior art (WO 95/02082,
WO 97/38153) in that the air gap length does not constitute a
relevant parameter. Fibers according to the invention are obtained
already with an air gap length starting from 20 mm.
[0127] iii) Climate within the air gap: The production of the fiber
according to the invention also differs from the prior art (WO
95/02082, WO 97/38153) in that the humidity and the temperature of
the blowing air do not constitute relevant parameters. Humidity
values of the blowing air of between 0 g/kg air and 30 g/kg air are
applicable, and the temperature of the blowing air may range
between 10.degree. C. and 30.degree. C. (it is known to a person
skilled in the art that, for a given humidity setpoint of the
blowing air, a minimum air temperature corresponding to a relative
humidity of 100% cannot be fallen short of).
[0128] The speed of the blowing air in the air gap is lower than
for the production of Lyocell fibers which currently are
commercially available and should be below 3 m/sec, preferably at
about 1-2 m/sec.
[0129] iv) Draft in the air gap: The value of the draft in the air
gap (quotient of the haul-off speed from the spinning bath to the
extrusion speed from the nozzle) should be below 7. Given a defined
titer of the fiber, a small draft is achievable by using nozzles
with small hole diameters. Nozzles having a hole diameter of
.ltoreq.100 .mu.m are usable, nozzles having a hole diameter of
between 40 .mu.m and 60 .mu.m are preferred.
[0130] v) Spinning temperature: Spinning must occur at a
temperature as high as possible, which is limited only by the
thermostability of the solvent. However, it must not fall short of
a value of 130.degree. C.
[0131] vi) The spinning bath temperature may range between
0.degree. C. and 40.degree. C., values of from 0.degree. C. to
10.degree. C. are preferred.
[0132] vii) During the transport of the fiber from the spinning
bath into the aftertreatment and during the aftertreatment, the
filaments should be exposed, according to WO 97/33020, to a tensile
load in the longitudinal direction of not more than 5.5 cN/tex.
[0133] It has been shown that, if the above parameters are met,
Lyocell fibers which comply with the relations according to the
invention with regard to the two Holler factors F1 and F2 and thus
have more "viscose-like" properties are obtained in a reproducible
way.
[0134] The present invention also relates to a fiber bundle
comprising a plurality of fibers according to the invention. A
"fiber bundle" is understood to be a plurality of fibers, for
example, a plurality of staple fibers, a strand of continuous
filaments or a bale of fibers.
Measuring Methods:
Testing of Textile-Mechanical Properties:
[0135] The determination of the titer of the fibers (linear
density) was carried out according to BISFA regulation "Testing
methods viscose, modal, lyocell and acetate staple fibers and tows"
Edition 2004 Chapter 6 by means of a vibroscope, type Lenzing
Technik.
[0136] The determination of the maximum tensile force (breaking
tenacity), of the maximum tensile force elongation (elongation at
break) in the conditioned and wet state, and of the wet modulus was
carried out, according to the above-mentioned BISFA regulation,
Chapter 7, by means of a tensile testing device Lenzing Vibrodyn
(device for tensile tests on single fibers at a constant
deformation speed).
[0137] The loop strength was determined on the basis of DIN 53843,
Part 2, in the following way:
The titers of the two fibers used for the test are determined on
the vibroscope. For determining the loop strength, the first fiber
is formed into a loop and clamped with both ends into the pre-load
weight (size of the pre-load weight according to the
above-mentioned BISFA regulation, Chapter 7). The second fiber is
drawn into the loop of the first fiber and the ends are placed into
the upper clamp (measuring head) of the tensile testing device in
such a way that the interlacing is located in the middle of the two
clamps. After the pre-load has levelled out, the lower clamp is
closed and the tensile test is started (clamping length 20 mm,
traction speed 2 mm/min). It should be made sure that the breakage
of the fiber occurs at the loop arc. As a titer-related loop
strength, the measured maximum tensile force value, which has been
obtained, is divided by the smaller one of the two fiber
titers.
[0138] The knot strength was determined on the basis of DIN 53842,
Part 1, in the following way:
A loop is formed from the fiber to be tested, one end of the fiber
is drawn through the loop and, thus, a loose knot is formed. The
fiber is placed into the upper clamp of the tensile testing device
in such a way that the knot is located in the middle between the
clamps. After the pre-load has levelled out, the lower clamp is
closed and the tensile test is started (clamping length 20 mm,
traction speed 2 mm/min). For the evaluation, only results are used
in which the fiber has actually broken at the knot.
Determination of the Fibrillation Behavior According to the Wet
Abrasion Method:
[0139] The method described in the publication by Helfried Stover:
"Zur Fasernassscheuerung von Viskosefasern" Faserforschung und
Textiltechnik 19 (1968) Issue 10, p. 447-452, was employed.
[0140] The principle is based on the abrasion of single fibers in
the wet state using a rotating steel shaft coated with a viscose
filament hose. The hose is continuously moistened with water. The
number of revolutions until the fiber has been worn through and the
pre-load weight triggers a contact is determined and related to the
respective fiber titer.
[0141] Device: Abrasion Machine Delta 100 of Lenzing Technik
Instruments Departing from the above-cited publication, the steel
shaft is continuously shifted in the longitudinal direction during
the measurement in order to prevent the formation of grooves in the
filament hose.
Source of supply of the filament hose: Vom Baur GmbH & KG.
Marktstra e 34,
D-42369 Wuppertal
Test Conditions:
[0142] Water flow rate: 8.2 ml/min Speed of rotation: 500 U/min
Abrasion angle: 40 for titer 1.3 dtex, 500 for titer 1.7 dtex, 500
for titer 3.3 dtex Pre-load weight: 50 mg for titer 1.3 dtex, 70 mg
for titer 1.7 dtex, 150 mg for titer 3.3 dtex
Determination of the Abrasion Resistance of Planar Assemblies
According to Martindale:
[0143] Methods according to the standard "Determination of the
Abrasion Resistance of Planar Textile Assemblies by means of the
Martindale Method--Part 2: Definition of the Destruction of Samples
(ISO 12947-2:1998+Cor.1:2002; German version EN ISO
12947-2:1998+AC:2006).
Examples
[0144] The pulps and pulp mixtures, respectively, described below
in Table 1 were processed into spinning masses of the composition
indicated in Table 2 and spun into fibers having a titer of approx.
1.2 to approx. 1.6 dtex by a spinning method according to WO
93/19230 under the conditions of Table 2.
[0145] Constant parameters not indicated in the table are:
[0146] the spinning mass output of 0.02 g/hole/min
[0147] the air gap of 20 mm
[0148] the humidity of the blowing air of 8-12 g H.sub.2O/kg
air
[0149] the temperature of the blowing air of 28-32.degree. C.
[0150] the speed of the blowing air in the air gap of 2 m/sec
[0151] The textile-mechanical data of the obtained fibers are
indicated in Table 3. The Holler factors calculated from the
textile data, the wet abrasion value and the flexibility of the
fibers can be seen in Table 4. The results clearly show the impact
of the pulp and the particular importance of the spinning
temperature.
TABLE-US-00001 TABLE 1 limiting amount viscosity alpha of DP <
number content 50 DP > Pulp code ml/g % % 2000 Solucell 250 So
250 270 91.8 1.3 2.8 Borregard Derivative Bo HV 1030 n.b. 1.4 49.1
HV Saiccor Sai 383 90.4 6.6 14.9 Borregard Derivative Bo VHV 1500
92.7 n.b. n.b. VHV Solucell 400 So 400 415 94.9 1.9 11.8 Cotton
Linters low Co LV 396 97.1 0.6 0 MW Cotton Linters high Co HV 2030
99.1 0 98.3 MW Reclaimed cotton RCF LV 423 97.1 0.45 7.7 fibers,
low MW Reclaimed cotton RCF HV 1840 97.8 0 68.7 fibers, high MW
[0152] The pulps "RCV LV" and "RCV HV" were produced according to
the teaching of the publication "Process for pretreating reclaimed
cotton fibers to be used in the production of moulded bodies from
regenerated cellulose" (Research Disclosure,
www.researchdisclosure.com, database number 609040, published
digitally Dec. 11, 2014).
TABLE-US-00002 TABLE 2 cellulose water pulp or pulp ratio
high-molecular in spinning in spinning spinning spinning bath
mixture, amount/low- mass mass nozzle temperature temperature
respectively molecular amount % % .mu. draft .degree. C. .degree.
C. Example 1 Co HV/Co LV 10/90 11 12 40 1.54 131 0 Example 2 Co
HV/Co LV 10/90 11 12 50 2.41 131 0 Example 3 Co HV/Co LV 10/90 11
12 60 3.47 130 0 Example 4 Co HV/Co LV 10/90 11 12 80 6.17 130 0
Example 5 Co HV/Co LV 10/90 11 12 60 3.47 130 20 Example 6 Co HV/Co
LV 10/90 11 10.5 50 2.41 132 0 Example 7 Co HV/Co LV 10/90 11 10.5
50 2.41 132 20 Example 8 Co HV/Co LV 10/90 13 11.7 50 2.85 131 0
Example 9 Co HV/Co LV 5/95 13.5 10 50 2.96 130 20 Example 10 Co
HV/Co LV 5/95 13.5 10 50 2.96 131 0 Example 11 Bo HV/So 250 30/70
11 12 40 1.54 130 20 Example 12 Bo HV/So 250 30/70 11 12 50 2.41
130 20 Example 13 Bo HV/So 250 30/70 11 12 60 3.47 130 20 Example
14 Bo HV/So 250 30/70 11 12 70 4.73 130 20 Example 15 Bo VHV/So 400
24/76 11 12 50 2.41 132 20 Example 16 RCF HV/ 10/90 11 12 50 2.41
130 0 RCF LV Example 17 Bo VHV/ 10/90 11 12 50 2.41 132 0 RCF LV
Comparative Co HV/Co LV 5/95 13.5 10 50 2.96 122 0 Example 1
Comparative Co HV/Co LV 10/90 11 12 100 9.64 130 20 Example 2
Comparative Sai 12.8 10.5 40 1.80 132 20 Example 3 Comparative Sai
13 10.5 100 11.4 124 20 Example 4 (commercial Lyocell fiber)
TABLE-US-00003 TABLE 3 titer FFk FDk FFn FDn NM SFk KFk dtex cN/tex
% cN/tex % cN/tex, 5% cN/tex cN/tex Example 1 1.37 21.8 15.2 16.7
22.8 4.2 14.8 21.3 Example 2 1.37 25.1 21.5 17.8 28.2 3.9 15.7 23.3
Example 3 1.37 26.4 17.4 19.0 22.2 4.8 16.3 23.3 Example 4 1.37
26.3 16.5 20.8 22.8 5.4 17.5 25.1 Example 5 1.36 26.0 14.0 17.5
20.5 4.7 14.5 22.7 Example 6 1.23 24.5 19.0 18.7 25.5 4.4 16.1 22.5
Example 7 1.34 24.7 17.5 20.0 24.4 5.5 16.7 24.1 Example 8 1.54
26.4 16.1 19.5 21.7 4.7 17.4 23.6 Example 9 1.29 27.5 14.9 20.5
21.0 5.8 20.6 24.9 Example 10 1.37 24.8 17.8 19.4 24.2 4.5 19.1
23.6 Example 11 1.34 21.3 14.1 14.9 22.8 3.6 11.5 19.2 Example 12
1.30 24.1 15.2 15.4 19.2 4.4 10.2 19.4 Example 13 1.37 22.9 15.9
18.1 22.7 4.4 11.1 20.3 Example 14 1.30 25.3 14.6 19.4 21.8 5.0
12.0 20.5 Example 15 1.30 27.5 16.9 22.7 22.8 6.0 13.2 23.8 Example
16 1.36 24.6 16.0 18.5 23.9 4.2 14.8 22.4 Example 17 1.32 23.1 16.5
17.9 24.5 4.0 14.1 20.9 Comparative 1.30 28.8 15.0 21.1 23.6 5.3
20.9 25.2 Example 1 Comparative 1.43 27.7 11.1 21.6 16.1 8.1 16.7
25.0 Example 2 Comparative 1.31 30.1 13.5 22.3 16.4 6.9 11.3 21.1
Example 3 Comparative 1.37 39.3 13.6 34.9 18.6 10.6 18.9 31.7
Example 4 commercial Lyocell fiber
TABLE-US-00004 TABLE 4 Holler wet abrasion value factor Holler
factor revolutions until flexibility F 1 F 2 breakage FDk/FFk
Example 1 -0.05 3.20 1951 0.70 Example 2 -0.45 4.39 1947 0.86
Example 3 0.27 4.22 664 0.66 Example 4 0.51 4.88 370 0.63 Example 5
0.40 3.33 244 0.54 Example 6 -0.12 4.16 1427 0.78 Example 7 -0.07
5.02 1455 0.71 Example 8 0.42 4.53 511 0.61 Example 9 0.84 5.61 303
0.54 Example 10 0.17 5.15 635 0.72 Example 11 -0.28 1.82 336 0.66
Example 12 -0.04 1.45 585 0.63 Example 13 -0.09 2.06 410 0.70
Example 14 0.27 2.36 312 0.58 Example 15 0.52 3.49 443 0.62 Example
16 0.08 3.59 1153 0.65 Example 17 -0.14 3.13 821 0.71 Comparative
1.21 5.94 332 0.52 Example 1 Comparative 1.45 4.16 125 0.40 Example
2 Comparative 1.05 2.17 30 0.45 Example 3 Comparative 2.72 6.17 40
0.34 Example 4 commercial Lyocell fiber
[0153] FIG. 3 shows the position of the examples/comparative
examples in the Holler chart as well as the area of the chart which
is claimed according to the invention. Therein, examples 1 to 17
(according to the invention) are designated with their respective
numbers, while the comparative examples 1 to 4 are designated with
a pre-fix "V", respectively.
[0154] Comparative Example 1 demonstrates that the object according
to the invention is not achieved if the spinning temperature,
which, at 122.degree. C., is below the required value of at least
130.degree. C. even if all remaining manufacturing parameters
correspond to the parameters for the production of the fiber
according to the invention.
[0155] Comparative Example 2 demonstrates that the object according
to the invention is not achieved if the draft, which, at 9.64, is
above the required value of less than 8.00, even if all remaining
manufacturing parameters correspond to the parameters for the
production of the fiber according to the invention.
[0156] Comparative Example 3 demonstrates the significance of the
pulp. The object according to the invention is not achieved if the
pulp composition, which, with a single pulp, fails to exhibit the
necessary proportion of a very high and a low molecular weight,
even if all remaining manufacturing parameters correspond to the
parameters for the production of the fiber according to the
invention.
[0157] Comparative Example 4 shows the properties and the position
in the Holler chart of a commercial Lyocell fiber (Tencel.RTM. of
Lenzing AG).
Processing Example
[0158] A 130 kg bale of a fiber of 1.3 dtex/38 mm according to
Example 11 was processed into a ring yarn Nm 50. A single jersey
with a mass per unit area of 150 g/m2 was produced from said yarn.
A sample of this single jersey was dyed with 4% Novacronmarine FG,
bath ratio 1:30, at 60.degree. C. in a laboratory jet for 45 min
and subsequently subjected to 15 household washings at 60.degree.
C.
[0159] Table 5 shows the abrasion and washing behavior of this
single jersey in comparison to a planar assembly of the same
structure made of a commercial viscose or Lyocell fiber,
respectively.
TABLE-US-00005 TABLE 5 Lyocell Fiber according to viscose 1.3
standard 1.3 Example 11 dtex dtex Abrasion Martindale 57 500 58 750
15 500 tours until hole formation Washing test Grey scale* Grade
after 1st washing 4-5 4 3-4 Grade after 5th washing 4-5 4 1 Grade
after 10th washing 3 4-5 2 Grade after 15th washing 2-3 4-5 1
*Grades from 1 to 5, the best grade is 5
* * * * *
References