U.S. patent application number 12/419996 was filed with the patent office on 2009-10-15 for method of producing cellulose carbamate fibre and use of the same.
This patent application is currently assigned to FRAUNHOFER-GESELLSCHAFT zur Forderung der angewandten Forschung e.V.. Invention is credited to Horst Ebeling, Hans-Peter Fink.
Application Number | 20090258227 12/419996 |
Document ID | / |
Family ID | 40929801 |
Filed Date | 2009-10-15 |
United States Patent
Application |
20090258227 |
Kind Code |
A1 |
Ebeling; Horst ; et
al. |
October 15, 2009 |
METHOD OF PRODUCING CELLULOSE CARBAMATE FIBRE AND USE OF THE
SAME
Abstract
The invention relates to a cellulose carbamate spinning
solution, cellulose fibres and a method for the production thereof
in which a solution of cellulose carbamate in an ionic liquid is
pressed through the holes of a spinning nozzle. The shaped fibres
are stretched in air and the cellulose carbamate is regenerated in
an aqueous bath. Solvent is removed by washing and the fibre is
subsequently dried.
Inventors: |
Ebeling; Horst; (Premnitz,
DE) ; Fink; Hans-Peter; (Teltow, DE) |
Correspondence
Address: |
LEYDIG VOIT & MAYER, LTD
TWO PRUDENTIAL PLAZA, SUITE 4900, 180 NORTH STETSON AVENUE
CHICAGO
IL
60601-6731
US
|
Assignee: |
FRAUNHOFER-GESELLSCHAFT zur
Forderung der angewandten Forschung e.V.
Munchen
DE
|
Family ID: |
40929801 |
Appl. No.: |
12/419996 |
Filed: |
April 7, 2009 |
Current U.S.
Class: |
428/364 ;
264/195 |
Current CPC
Class: |
Y10T 428/2913 20150115;
C08L 1/08 20130101; D01F 2/24 20130101 |
Class at
Publication: |
428/364 ;
264/195 |
International
Class: |
D02G 3/02 20060101
D02G003/02; D01F 11/02 20060101 D01F011/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 14, 2008 |
DE |
10 2008 018 743.7 |
Claims
1.-9. (canceled)
10. A method of producing spun cellulose carbamate fibres,
comprising (a) pressing a spinning solution through a spinning
nozzle which has at least one opening, to form a spinning solution
thread, wherein the spinning solution is a cellulose carbamate
spinning solution comprising a solution of cellulose carbamate in
at least one ionic liquid, wherein the cellulose carbamate
concentration of the spinning solution is at least 15% by weight
and the zero shear viscosity, measured at 100.degree. C., is in the
range of 50 to 7,500 Pas; (b) stretching the spinning solution
thread in an air gap; and (c) subsequently coagulating the spinning
solution thread in a precipitation bath.
11. The method of claim 10, wherein the 1/d ratio of the spinning
nozzle is from 2 to 20.
12. The method of claim 10, wherein the width of the air gap is
from 5 to 250 mm.
13. The method of claim 10, wherein an aqueous solution of at least
one ionic liquid is used in the precipitation bath.
14. The method of claim 13, wherein the weight concentration of the
at least one ionic liquid in the aqueous solution is from 0.5 to
50% by weight.
15. The method of claim 10, wherein the temperature of the spinning
solution is from 50 to 150.degree. C.
16. Cellulose carbamate fibre, produced by the method of claim
10.
17. The fibre of claim 16, wherein the fibre has a strength of at
least 30 cN/tex measured according to DIN 53834.
18. The fibre of claim 16, wherein the fibre has a modulus of
elasticity of at least 1,500 cN/tex.
19. The fibre of claim 16, wherein the fibre has a nitrogen content
between 0.01 and 7% by weight.
20. A precursor for industrial fibres comprising the fibre of claim
16.
21. A reinforcing fibre for plastic materials or composites
comprising the fibre of claim 16.
22. The method of claim 10, wherein the ionic liquid has a melting
point below 100.degree. C.
23. The method of claim 10, wherein the ionic liquid is selected
from the group consisting of ammonium-, pyrazolium-, cholinium-, in
1- and 3-position alkyl- or aryl-substituted imidazolium compounds,
and mixtures thereof.
24. The method of claim 23, wherein the ionic liquid is selected
from the group consisting of butyl methylimidazolium acetate, butyl
methylimidazolium chloride, ethyl methylimidazolium chloride, ethyl
methylimidazolium acetate, butyl ethylimidazolium acetate, butyl
ethylimidazolium chloride, methyl tetradecylimidazolium chloride,
butyl methylimidazolium bromide, butyl methylpyridinium chloride,
butyl methylimidazolium thiocyanate, ethyl methylimidazolium
thiocyanate, butyl ethylimidazolium thiocyanate, hexyl
dimethylimidazolium hexafluoroborate, ethoxy methyl
methylpyrrolidinium chloride, hydroxypropyl methylimidazolium
acetate, hydroxypropyl methylimidazolium chloride, butyl
methylpyridinium chloride, and mixtures thereof.
25. The method of claim 10, wherein the cellulose carbamate has a
DP.sub.cuoxam of 150 to 750.
26. The method of claim 10, wherein the cellulose carbamate has a
substitution degree DS.sub.carbamate of 0.1 to 1.
27. The method of claim 10, wherein the cellulose carbamate
concentration is between 20 and 50% by weight.
28. The method of claim 10, wherein dried cellulose carbamate is
used for the production of the spinning solution.
29. The method of claim 10, wherein water-containing cellulose
carbamate is used for the production of the spinning solution and
the dissolving process is implemented at a reduced pressure of less
than 0.9 bar.
30. The method of claim 10, wherein the zero shear viscosity,
measured at 100.degree. C., is in the range of 50 to 5,000 Pas.
Description
[0001] The invention relates to a cellulose carbamate spinning
solution, cellulose fibres and a method for the production thereof
in which a solution of cellulose carbamate in an ionic liquid is
pressed through the holes of a spinning nozzle. The shaped fibres
are stretched in air and the cellulose carbamate is regenerated in
an aqueous bath. The solvent is removed by washing and the fibre is
subsequently dried.
[0002] The production of cellulose fibres according to the viscose
process is still the mostly used method (K. Gotze, "Chemical Fibres
According to the Viscose Method", Springer Press, Berlin Heidelberg
New York 1967). Since the viscose method is associated with
significant environmental impact, e.g. due to carbon disulphide,
hydrogen sulphide, heavy metals, and also with high investment
costs, efforts have already been made for years to replace the
viscose method by alternative methods. Methods have been developed
on the basis of direct dissolving of pulp in a suitable solvent or
alternative derivatisation variants without carbon disulphide.
[0003] The cuproammonium method which is based on the solubility of
pulp in copper oxide ammonia solution is comparable to the viscose
method from the initiation time (Ullmann's Encyclopedia of
Industrial Chemistry: Cellulose--3.3 Cuprammonium Fibres).
[0004] One method (Tencel.RTM.) introduced for the production of
cellulose fibres is the spinning of solutions of cellulose in amine
oxides, preferably in N-methylmorpholine-N-oxide (NMMO), not least
because by means of this the complex route via derivatisation of
the cellulose is avoided. It is known from DE 28 30 685 and U.S.
Pat. No. 3,767,756 and also EP 0 490 870 that cellulose is soluble
in an NMMO water system and can be processed to form textile fibres
by spinning in a generally aqueous NMMO solution
[0005] A further known possibility for the production of moulded
articles made of regenerated cellulose resides in precipitating a
solution of cellulose carbamate (EP 57 105, EP 178 292) which is
formed by conversion of cellulose with urea. Cellulose carbamate is
soluble in cold sodium hydroxide solution and can be regenerated
again into cellulose in heated sodium hydroxide solution.
[0006] The low solids concentration of the cellulose in the
spinning solution which is generally 8 to 15% is disadvantageous
for the productivity of the described cellulose wet spinning
methods.
[0007] The use of concentrations above 20% for the production of
cellulose fibres on the basis of extrusion of solutions of
cellulose carbamate in NMMO is described in DE 10 2004 007 616. In
this method, the high spinning solution viscosities have a
disadvantageous effect. The spinning solution production is
effected by swelling the cellulose carbamate in a 40 to 70%
NMMO/water mixture and subsequent distilling-off of water, which
demands significant dissolving times and a fairly high energy
requirement.
[0008] Ionic liquids have been described as a further solvent for
cellulose in recent times. Ionic liquids are salts which are
constructed from a cyclic, generally nitrogen-containing cation and
an organic or inorganic anion and have a melting point below
100.degree. C. Possibilities for synthesis of ionic liquids, the
use as medium in chemical reactions and also as solvents for
cellulose and also the formation of these solutions into fibres are
described in the subsequently mentioned publication (G. Laus, G.
Bentivoglio, H. Schottenberger, V. Kahlenberg, H. Kopacka, T.
Roder, H. Sixta, "Ionic Liquids: Current Developments, Potential
and Drawbacks for Industrial Applications" in Lenzinger Berichte,
84 (2005) 71-85).
[0009] In WO 2006/000197, a method and device for the production of
moulded articles from solutions of cellulose in ionic liquids are
described. The pulps are disintegrated here in water and supplied
to the dissolving process in wet form. This means that the water
must be removed during dissolving, as a result of which the
dissolving time and the energy requirement are affected. The
described spinning solutions with concentrations up to 20% have
very high zero shear viscosities.
[0010] Starting herefrom, it was the object of the present
invention to provide a cellulose carbamate spinning solution in
which the cellulose carbamate is present in high concentrations in
dissolved form. It was also the object of the present invention to
provide, in comparison with existing methods, an environmentally
friendly method for the production of qualitatively high-quality
cellulose fibres, which method fulfils the demands with respect to
low investment and production costs due to high solution
concentrations. A further object of the invention was to indicate a
correspondingly produced fibre and also possibilities for using the
fibre.
[0011] This object is achieved with respect to the cellulose
carbamate spinning solution by the features of patent claim 1, with
respect to the method for the production of spun cellulose
carbamate fibres by the features of patent claim 10, with respect
to the cellulose carbamate fibres by the features of patent claim
16 and also with respect to the possibilities for using the fibres
by the features of patent claim 20 and 21. The respective dependent
claims demonstrate advantageous developments.
[0012] According to the invention, a spinning solution made of
cellulose carbamate is hence provided, the cellulose carbamate
being dissolved in at least one ionic liquid. According to the
invention, the cellulose carbamate concentration of the spinning
solution is thereby at least 15% by weight and the zero shear
viscosity, measured at 100.degree. C., is thereby in a range of 50
to 7,500 Pas.
[0013] It was shown surprisingly that cellulose carbamate dissolves
in ionic liquids up to high concentrations and can be shaped to
form fibres with high strengths. It was likewise shown surprisingly
that the highly-concentrated solutions, compared to cellulose in
ionic liquids and also to cellulose carbamate in NMMO, have far
lower zero shear viscosities at the processing temperature.
[0014] For the production of the spinning solution according to the
invention, cellulose carbamate is dissolved in an ionic liquid with
agitation or kneading at temperatures above 80.degree. C. and the
resulting spinning solution is filtered.
[0015] Preferably, dried cellulose carbamate is used for production
of the spinning solution and the spinning solution is formed by
mechanical mixing at temperatures between 80 and 120.degree. C.,
preferably between 90 and 100.degree. C. When using
water-containing cellulose carbamate, the dissolving is effected by
kneading with simultaneous withdrawal of the water at reduced
pressure, e.g. less than 0.9 bar.
[0016] In an advantageous embodiment, the melting point of the at
least one ionic liquid is below 100.degree. C., preferably below
75.degree. C., particularly preferred below 50.degree. C.
[0017] The at least one ionic liquid is thereby selected preferably
from the group consisting of ammonium-, pyrazolium-, cholinium-, in
1- and 3-position alkyl- or aryl-substituted imidazolium compounds
and/or mixtures hereof, in particular butyl methylimidazolium
acetate, butyl methylimidazolium chloride, ethyl methylimidazolium
chloride, ethyl methylimidazolium acetate, butyl ethylimidazolium
acetate, butyl ethylimidazolium chloride, methyl
tetradecylimidazolium chloride, butyl methylimidazolium bromide,
butyl methylpyridinium chloride, butyl methylimidazolium
thiocyanate, ethyl methylimidazolium thiocyanate, butyl
ethylimidazolium thiocyanate, hexyl dimethylimidazolium
hexafluoroborate, ethoxy methyl methylpyrrolidinium chloride,
hydroxypropyl methylimidazolium acetate, hydroxypropyl
methylimidazolium chloride and/or butyl methylpyridinium
chloride.
[0018] Further advantages are produced if the cellulose carbamate
has a DP.sub.cuoxam of 150 to 170, preferably of 250 to 550.
[0019] It is likewise preferred if the cellulose carbamate has a
substitution degree DS.sub.carbamate of 0.1 to 1, preferably of 0.2
to 0.6.
[0020] It must be emphasised as a particular advantage of the
present invention that high concentrations of cellulose carbamate
in solution can be set by dissolving the cellulose carbamate in an
ionic liquid. The cellulose carbamate concentration can thus assume
high concentration values, advantageously between 20 and 50% by
weight, further preferred between 20 and 40% by weight,
particularly preferred between 20 and 30% by weight.
[0021] Further advantages of the spinning solution according to the
invention can be seen in the fact that, despite the high cellulose
carbamate content, low zero shear viscosities are produced.
Preferred ranges of the zero shear viscosity, measured at
100.degree. C., are thereby in the range of 50 to 5,000 Pas,
preferably of 150 to 2,500 Pas and particularly preferred of 250 to
1,250 Pas.
[0022] According to the invention, a method for the production of
cellulose carbamate fibres is likewise provided, in which a
spinning solution is pressed through a spinning nozzle which has at
least one opening, the spinning solution thread formed thereby is
stretched in an air gap and coagulated subsequently in a
precipitation bath.
[0023] In the case of the method according to the invention, a
highly concentrated solution of cellulose carbamate in an ionic
liquid is hence formed by means of extrusion from a nozzle with
stretching in an air gap into a coagulation bath.
[0024] Preferably, the cellulose carbamate is dissolved with
agitation or kneading at temperatures above 80.degree. C. in an
ionic liquid, the resulting spinning solution is filtered and
subsequently pressed through the holes of a nozzle. The resulting
threads or formed items can be withdrawn at speeds of greater than
50 m/min via an air gap and a subsequent coagulation bath. In the
air gap, drawing to a multiple of the original length is effected
preferably and the carbamate formed item is coagulated in a
coagulation bath and a part of the solvent is thereby removed.
Subsequently the remaining solvent is washed out preferably in the
counterflow principle and the product is dried.
[0025] Advantageously, spinning nozzles are used in the method, the
1/d ratio of which, i.e. the ratio between the length of the
spinning nozzle hole to the diameter, is 2 to 20, preferably 6 to
15.
[0026] Furthermore, it is advantageous if the width of the air gap
is from 5 to 250 mm.
[0027] An aqueous solution at least of one ionic liquid is used
preferably as precipitation bath. It is hereby preferred if the
weight concentration of the at least one ionic liquid in the
aqueous solution is 0.5 to 50% by weight, preferably 2 to 25% by
weight.
[0028] The temperature of the spinning solution during the spinning
process is adjusted preferably to a temperature range of 50 to
150.degree. C., preferably of 80 to 120.degree. C. The spinning
solution is thereby spun in particular according to a dry/wet jet
method to form fibres.
[0029] According to the invention, cellulose carbamate fibres are
likewise provided which are produced according to a previously
described method. The fibres according to the invention are
distinguished by very high strength.
[0030] The fibres according to the invention can be produced by
varying the regeneration conditions with a varying N-content and
have, as a function of the N-content, a different water absorption
capacity.
[0031] The strength of cellulose carbamate fibres is in particular
at least 30 cN/tex, preferably at least 50 cN/tex, measured
according to DIN 53834.
[0032] Likewise, the fibres are distinguished by a high modulus of
elasticity which is preferably 1,500 cN/tex, preferably at least
2,500 cN/tex.
[0033] The nitrogen content of the fibres can thereby vary
preferably in a range between 0.01 and 7% by weight, preferably
between 0.5 and 5% by weight.
[0034] Possibilities for use according to the invention of the
cellulose carbamate fibres are thereby precursors for industrial
fibres, in particular for the production of carbon fibres or
reinforcing fibres for plastic materials or composites.
[0035] The subject according to the invention is intended to be
explained in more detail with reference to the subsequent examples
without wishing to restrict the latter to the special embodiments
shown here.
Embodiments
EXAMPLE 1
[0036] 20 g cellulose carbamate (DPcuox: 258, DS 0.4) are mixed
with 80 g butyl methylimidazolium acetate and are dissolved in a
horizontal kneader at 110.degree. C. within 2 hours. The resulting
homogeneous, dark brown solution is completely fibre-free. The
viscosity of the solution, measured at 100.degree. C., is 64
Pas.
[0037] The solution was pressed by means of an extruder through a
12-hole spinning nozzle (hole diameter 150 .mu.m), stretched with a
drawing ratio of 30 in the air gap and the cellulose carbamate
fibre was precipitated in the aqueous coagulation bath with 12%
butyl methylimidazolium acetate. The filaments were washed with
soft water and dried at 90.degree. C.
[0038] The filaments had a strength of 52 cN/tex, a stretch of 9%
and a modulus of 2,500 cN/tex.
EXAMPLE 2
[0039] 30 g cellulose carbamate (DPcuox: 258, DS 0.4) are mixed
with 70 g butyl methylimidazolium acetate and are dissolved in a
horizontal kneader at 110.degree. C. within 2 hours. The resulting
homogeneous, dark brown solution is completely fibre-free. The
viscosity of the solution, measured at 100.degree. C., is 1,210
Pas.
[0040] The solution was pressed by means of an extruder through a
12-hole spinning nozzle (hole diameter 150 .mu.m), stretched with a
drawing ratio of 35 in the air gap and the cellulose carbamate
fibre was precipitated in the aqueous coagulation bath with 15%
butyl methylimidazolium acetate. The filaments were washed with
soft water and dried at 90.degree. C.
[0041] The filaments had a strength of 62 cN/tex, a stretch of 8%
and a modulus of 2,970 cN/tex.
EXAMPLE 3
[0042] 20 g cellulose carbamate (DPcuox: 258, DS 0.4) are mixed
with 80 g butyl methylimidazolium chloride and dissolved in a
horizontal kneader at 110.degree. C. within 2 hours. The resulting
homogeneous, yellowish solution is completely fibre-free. The
viscosity of the solution, measured at 100.degree. C., is 504
Pas.
[0043] The solution was pressed by means of an extruder through a
12-hole spinning nozzle (hole diameter 150 .mu.m), stretched with a
drawing ratio of 30 in the air gap and the cellulose carbamate
fibre was precipitated in the aqueous coagulation bath with 12%
butyl methylimidazolium chloride. The filaments were washed with
soft water and dried at 90.degree. C.
[0044] The filaments had a strength of 58 cN/tex, a stretch of 11%
and a modulus of 2,400 cN/tex.
EXAMPLE 4 (COMPARATIVE EXAMPLE)
[0045] 15 g of a prehydrolysis kraft pulp (DPcuox: 552) are
disintegrated in water and subsequently mixed with 85 g butyl
methylimidazolium acetate and dissolved in a horizontal kneader at
150 mbar at 80 to 85.degree. C. within 3 hours. The resulting
homogeneous, brown solution is fibre-free. The viscosity of the
solution, measured at 100.degree. C., is 1,649 Pas.
[0046] The solution was pressed by means of an extruder through a
12-hole spinning nozzle (hole diameter 150 .mu.m), stretched with a
drawing ratio of 30 in the air gap and the cellulose fibre was
precipitated in the aqueous coagulation bath with 12% butyl
methylimidazolium acetate. The filaments were washed with soft
water and dried at 90.degree. C.
[0047] The filaments had a strength of 41 cN/tex, a stretch of 9%
and a modulus of 1,590 cN/tex.
* * * * *