Title of Invention

A PROCESS FOR PRODUCING CONTINUOUS SHAPED CELLULOSE ARTICLES FROM PULP BY USING AQUEOUS AMINE OXIDES

Abstract The invention relates to a method for producing continuous moulded bodies consisting of cellulose, from pulp, according to the dry-wet extrusion technique. The inventive method comprises an improved thread-forming process which incorporates the determination of the pulp properties and the time-independent thermodynamic and time-dependent kinetic values of thread-formation in a ratio, respectively and which therefore enables the fibre, filament yarn or film properties to be calculated specifically, in advance, from the cellulose parameters in the solution and significant process parameters. This is achieved by fulfilling ratio (I) with (II) for fibres and filaments or (III) for films.
Full Text

[Description]
This invention relates to a process for producing continuous shaped cellulose articles from pulp by the dry-wet extrusion process using aqueous amine oxides, especially N-methylmorpholine N-oxide, which comprises a) pulp and aqueous amine oxide being mixed and converted into a homogeneous solution by water removal and shearing, b)the solution being fed to at least one shaping channel and shaped into a continuous shaped cellulose article, c) the shaped solution being transported through a noncoagulating medium with simultaneous further shaping, d) the continuous shaped cellulose article being exposed to a linear air or gas fl'bw substantially at right angles to its direction of transport shortly before entry into the coagulation bath, and e) the continuous shaped cellulose article being precipitated in a coagulation bath, diverted over a godet/roll to separate it from the coagulation bath, washed in a multistage aftertreatment apparatus, optionally bleached, finished, dried and wound up or cut into staple and dried,
[Prior art]
US 4 246 221 and US 4 416 698 disclose dissolving cellulose in aqueous amine oxides, shaping in spinning capillaries under low shear, stretching the solution jets in a large air gap, precipitating the cellulose by a spin bath containing aqueous amine oxide and withdrawing the cellulose filaments over a godet. US 5 417 909 describes a process which includes shaping the solution in the spinning capillaries .under high shear, stretching the solution jets in a short air gap, precipitating the cellulose and the filaments or sheet of filaments being gathered via a spinning funnel and transported

cocurrently. EP 0 430 926, EP 0 494 852, EP 0 756 025 and WO 94/28 210 describe certain dies having different spinning capillary geometries and arrangements. WO 96/20 300 concerns the spacing between two spinning capillaries and the distance between a spinning capillary and a deflecting element in the coagulation bath. EP 0 584 318, EP 0 671 492, EP 0 795 052, WO 94/28 218 and WO 96/21 758 describe a wide range of forms of treating the filament sheet in the gap between spinneret die and coagulation bath with air of differing water content* EP 0 797 694 claims to obtain lyocell fibers having improved properties by maintaining a relationship between pulp DP, cellulose concentration and takeoff speed of the form
The patent provides no indications as to the method for determining DP nor data concerning the change in DP during dissolving. According to DE 100 25 230 and DE 100 25 231, fibers possessing high loop tenacity and low fibrillation are obtained when the average heat flow and/or the average acceleration across the air gap height are controlled to a certain level.
EP 0 659 219 describes the production of a cellulose fiber having a reduced tendency to fibrillate by having an empirical formula derived from spinneret die hole diameter, dope output per hole, linear density, air gap height and moisture content of the quenching air not exceed a value of 10, EP 0731 856 claims to achieve a reduced tendency to fibrillate by having the quenching air contain aliphatic alcohols. EP 0 853 146 claims to achieve a reduced tendency to fibrillate by conducting the coagulation in two or more stages.
It is further known to modify fiber structure and properties by means of certain aftertreatment processes,

such as treatment with wetting agents EP 0 783 602, EP 0 796 358, with 10-18 % aqueous sodium hydroxide solution WO 97/45 574 or with alkanol, diol, -etriol in at least one washing bath WO 97/25 462.
WO 98/58102 and WO 98/58103 claim that the use of pulp mixtures having widely differing Dps and treating the fibers in the air gap with air of defined moisture content lead to increased spinning consistency and to fibers having special properties with regard to fineness and fibrillation.
All the processes mentioned fail to take proper account of the properties of the cellulose, especially in solution, do not consider the step of fiber formation in the lyocell process, i.e. the shaping in the die and in the air gap, as a unit, but predominantly statistically, and try to influence fiber structure and fiber properties through modifying individual steps such as, for example, pulp DP and cellulose blend, spinneret die geometry, water content of air gap atmosphere, coagulation bath design and/or aftertreatment,
[Object clause]
It is an object of the present invention to create a process which features an improved fiber-forming operation and which captures not only pulp properties but also time-independent thermodynamic and time-dependent kinetic variables of fiber formation in one mathematical expression each and thus permits controlled prediction of fiber, filament yarn or film properties from the cellulose parameters in solution and essential process parameters. It has been found that the properties of the "cellulose entanglement network" which is present in the polymer solution can be adequately characterized by the molar mass (expressed by the average degree of polymerization determined by the cuoxam method), the molar mass distribution (expressed by the rheologically

determined molecular dispersity), the cellulose concentration and the density and in that the shaping in the die channel under the influence of the pressure and in the air gap under the influence of the axial elongational tension must be considered as a unit and is characterized by the square root of the quotient formed from the inlet area of the shaping channel and the fineness of the continuous shaped article. According to the present invention, the process for producing continuous shaped articles consists of a plurality of steps which involve
a) pulp and aqueous amine oxide being mixed and converted into a homogeneous solution by water removal and shearing,
b) the solution being fed to at least one shaping channel and shaped into a continuous shaped cellulose article^
c) the shaped solution being transported through a noncoagulating medium with simultaneous further shaping,
d) the continuous shaped cellulose article being exposed to a linear air or gas flow substantially at right angles to its direction of transport shortly before entry into the coagulation bath,
e) the continuous shaped cellulose article being precipitated in a coagulation bath, diverted over a godet/roll to separate it from the coagulation bath, washed in a multistage aftertreatment apparatus, optionally bleached, finished, dried and wound up or cut into staple and dried,
and which satisfy the mathematical expression


are subject to A^ ~ H^-B^.
DE is the inlet diameter of the shaping channel in cm in
the case of fibers and films and H^ is the inlet height
and Bt: the inlet width of the shaping channel in cm in the
case of films. The factor of 105.4 is a dimensionless
conversion factor for the different dimensions and has no
particular physical meaning.
In the mathematical expression (1), the first term
describes the isotropic contribution of the strength of
the cellulose entanglement network and the second term

describes the orientation contribution of the strength due to the time-independent change in orientation during the two-step elongational shaping. Preferably, 30 Cuoxam DP is determined by precipitating the dissolved cellulose as a thin film, drying this thin film and dissolving it completely in cuoxam solution (consisting of 13 ± 0.6 g/1 of copper, 200 ± 5 g/1 of ammonia, 16 g/1 of ammonium chloride, 1 g/1 of dextrose) to form a 0.1% solution. The flow times of solution and solvent in a capillary viscometer are measured at 23 °C to determine the relative viscosity, from which the limiting viscosity is calculated by using the Schulz-Blaschke equation. The cuoxam DP is equal to twice the value of the cuoxam limiting viscosity.
The dispersity U,, is obtained from the quotient formed from the zero shear viscosity rio and the "viscosity contribution n"" at the crossing point of the dynamically recorded deformation curves [C; C' = f (co) ] , i.e. when the storage modulus G' and the loss modulus C' have the same magnitude.

The index n is intended to indicate that the dispersity results from rheological data and not from the determination of the number and mass averages of the molar mass. The measurements can be carried out using a plate and cone rheometer which permits not only rotation (ηo) but also oscillation (ηM directly on the polymer solution to be spun or on a separately prepared solution containing about 10-12 % of cellulose.
The method of determination is extensively described in the literature (Michels Ch, , Kosan B, Chemical Fibers

International in the press).
In a preferred embodiment of the process according to the present invention, not only the cellulose and time-independent parameters are controlled according to the equation (1) , but also the time-dependent, kinetic parameters in steps b) , c) and d) via the elongation rate according to the mathematical expression

In the mathematical expression (2) :
εD is the elongation rate in the shaping channel in s-1
εa is the elongation rate in the air gap in s-1
DA is the exit diameter of the shaping channel in cm
V3 is the takeoff speed in m/min
SVD is the spin-stretch ratio in the die channel

Vs is the exit speed from the shaping channel in m/min 1 is the length of the shaping channel in cm a is the length of the air gap in cm.
The elongation rate determines the "goodness" of structure development in continuous shaped articles, especially in the amorphous regions. As the elongation rate decreases, the loop tenacity and breaking extension in the case of fibers and the knot tenacity and breaking

extension in the case of filament yarns increase exponentially. Astonishingly, neither the L/D ratio of the cylindrical portion in the shaping channel nor its remaining geometry find reflection in the relationships found according to the present invention. The mathematical expressions (1) and (2) formally hold for one temperature only. But since molar mass, molar mass distribution, cellulose concentration and elongation rate determine the viscosity and the relaxation time of the entanglement network and these depend on the temperature, the relationship is established via the temperature

is chosen such that the zero shear viscosity in the shaping channel is between 2 000 and 10 000 Pas and preferably between 4 000 and 7 000 Pas and the relaxation time is between 0.5 and 80 s and preferably 1 and 8 s.
The invention will now be illustrated with reference to examples.
[Examples]
Example 1
A wood pulp of Chinese origin (cuoxam DP 694) , having been enzymatically activated, was, in a vertical kneader, mixed with aqueous amine oxide (84 % by mass of N-methyl-morpholine N-oxide) and converted, by heating and water removal, into a homogeneous solution having a cellulose content of 10.3 % by mass, a density of 1,163 g/cm3, a zero shear viscosity of 9 710 Pas and a relaxation time of 6.4 s at 85 °C. A viscosity contribution of 1 229 Pas at the crossing point of the dynamically recorded deformation functions of storage and loss moduli at 85 °C

results in a dispersity of 6.9,
The cuoxam DP of the cellulose in the solution before spinning was found to be 639. The shaping of the solution into fibers having a fineness of 1,30 dtex took place at a dope temperature of 90 °C through a spinning die whose spinning capillaries had an entry cross-section of 3,834-10-4 cm2. Inserting these parameters in mathematical expression (1) gives a tension value of 44.8.
The testing of the fibers resulted in the following parameters:

Example la
A portion of the solution of example 1 was shaped at 92oC through a round slot die having a diameter of 3 cm and an entry cross-section of 1,885 cm2 to form a film tube which was transported through the air gap under such an internal pressure that the 3 cm diameter of the film tube was preserved. Subsequently the film tube was washed, dried and cut into 1 cm wide strips for testing. The fineness of the film tube, having a thickness of 25 µm and a diameter of 3 cm, was 52 300 dtex. Putting these values into the mathematical expression (1) gives a stress value of 35.9.

Testing of the film strips produced the following values:

Example 2
A wood pulp of American origin (Weyerhaeuser Comp.) having a cuoxam DP of 446 was not pretreated before being dissolved similarly to example 1. The homogeneous solution contained 13-2 % of cellulose, had a density of 1-192 q/cm3, a zero shear viscosity of 3 050 Pas and a relaxation time of 5.5 s at 85oC. The cuoxam DP of the dissolved cellulose was 419 and the dispersity 7.6. The shaping of the solution at a dope temperature of 80 °C through spinning capillaries having an entry cross-section of 2.137-10-1 cm2 led to 1.85 dtex fibers, According to the mathematical expression (1), the stress parameter is 33.7.
Fiber testing gave the following values:

Example 3
A cotton linters pulp of Chinese origin (cuoxam DP 632)

was pjfocessed similarly to example 1 into a homogeneous solution having 12.3 % of cellulose, a density of 1,183 g/cm2, a zero shear viscosity of 7 200 Pas and a relaxation time of 1,6 s at 85oC. The cuoxam DP of the dissolved cellulose was 599 and the dispersity was 3.5. The spinning at 86 °C through spinning capillaries having an entry cross-section of 3.97-10-4 cm2 produced 0.9 dtex fibers. A stress value of 55.4 results for the mathematical expression (1) .

Fiber testing revealed the following values;

Example 4
A wood pulp of American origin (cuoxam DP 522) was to be spun into 1.30 dtex fiber having a breaking stress > 40 cN/tex and a loop tenacity > 20 cN/tex, The measuring of a solution having a cellulose content of 12.4 % revealed a cuoxam DP of 510, a density of 1.184 g/cm' at 85 °C, a zero shear viscosity of 6 100 Pas, a relaxation time of 4.4 s at 85 °C and a dispersity of 5,9. Putting these values into the mathematical relationship (1) gives a stress value of 42,9. To spin fibers having a loop tenacity > 20 cN/tex, the elongation rate should generally be below 25 s-1 according to mathematical expression (2). To shape the polymer solution in the die channel at a spinning dope temperature of 85.1 °C, a die was chosen with spinning capillaries of Di, = 221 µm, DEA = 140 µm and 1 = 0.05 cm. The cylindrical portion of the spinning capillary had an L/D ratio of 1. The shaping in the air gap at a = 6,0 cm was carried out at an ejection speed vs of 2.71 m/min and a takeoff speed vs of 52.4 m/min. Putting these parameters into mathematical expression (2) gives an elongation rate value of 13.4 s-1. After passing through 5-5.5 cm of the air gap, the filament bundle was subjected to an air stream of

10 1/min blown from a slot nozzle at right angles to the transport direction of the filament bundle.
Fiber testing revealed the following values:

Example 5
To spin a 40 dtex 32 filament yarn having a breaking
stress > 40 cN/tex and a knot strength > 24 cN/tex, a
cuoxam DP 544 wood pulp was dissolved in amine oxide to
form a homogeneous solution, which was measured. The
cuoxam DP of the dissolved cellulose was 510, the
cellulose concentration was 12.8 %, the dispersity was
5.8, the density at 85 °C was 1.188 g/cm3, the zero shear
viscosity was 5 850 Pas and the relaxation time was
4,3 s.
The elongation rate should be of the cellulose solution. The following parameters were
chosen for the spinning conditions:
spinning die containing 32 capillaries, De; = 225 µm,
DR - 90 µm and 1 = 0.05 cm. Air gap of a = 5 cm,
va = 23.2 m/min, va= 2 00 m/min.
After passing through 4-4 .5 cm of the air gap, the
filament bundle is subjected to an 8 1/min gas stream
blown from a slot nozzle at right angles to the direction

of transport.
The spinning test produced the following results:

Example 6
To spin a 750 dtex 750 filament industrial filament yarn having a breaking stress > 55 cN/tex and a knot strength > 40 cN/tex, a cuoxam DP 650 cotton 1inters pulp was selected, enzymatically pretreated and processed in amine oxide monohydrate to form a homogeneous solution. Measurement of the solution revealed a cellulose concentration of 12.5 %, a cuoxam DP of 626 for the dissolved cellulose, an 85°C density of 1.185, a zero shear viscosity of 5 600 Pas and a relaxation time of 1.6 s. The dispersity was 2,75, A knot strength of > 70 % of the yarn strength requires an elongation rate Shaping at a dope temperature of 86°C was carried out using a 70/30 gold/platinum spinneret die having 750 spinning capillaries 0.05 cm in length, 225 pm in inlet diameter and 90 pm in outlet diameter. The shaping in the air gap of a = 2. 5cm accelerated the f ilamients from the injection speed of 7.2 m/min to the takeoff speed of 75,2 m/min. Just above the coagulation bath surface, the filament bundle was subjected to a 12 1/min gas stream blown at right angles to the filament bundle's direction of transport from a slot nozzle.

The spinning test leads to the following result:



[Claims]
1. A process for producing continuous shaped cellulose articles from pulp by the dry-wet extrusion process using aqueous amine oxides, especially N-methylmorpholine N-oxide, which comprises
a) pulp and aqueous amine oxide being mixed and converted into a homogeneous solution by water removal and shearing,
b) the solution being fed to at least one shaping channel and shaped into a continuous shaped cellulose article,
c) the shaped solution being transported through a noncoagulating medium with simultaneous further shaping,
d) the continuous shaped cellulose article being exposed to a linear air or gas flow at right angles to its direction of transport shortly before entry into the coagulation bath,
e) the continuous shaped cellulose article being precipitated in a coagulation bath, diverted over a godet/roll to separate it from the coagulation bath, washed in a multistage aftertreatment apparatus, optionally bleached, finished, dried and wound up or cut into staple and dried,
characterized in that the operation in steps a) to e) satisfies the mathematical expression


where DE is the inlet diameter of the shaping channel in the case of fibers and filaments and HE is the inlet height and BE the inlet width of the shaping channel in the case of films.
2, A process according to claim 1, characterized in that
the average degree of poJ,ymerization is in the
range 350-2 000, preferably 4 50-7 50 and the molecular dispersity UE is in the range 1,5-12 and preferably 2,5-7.
3, A process according to claim 1, characterized in that
the shaping channel inlet diameter DE is in the range
0,015-0.3 cm and preferably 0.018-0,03 cm in case of
filaments and fibers,
4. A process according to claim 1, characterized in that
in the case of films the shaping channel inlet cross
section AE follows from the product and the
shaping channel inlet height HE- is in the range 0,5-0,05 cm,
5. A process according to claim 1, characterized in that
the cellulose concentration Ccell. is 3-16 %, preferably 9-
14 %.
6, A process according to claim 1, characterized in that
the fineness of filamentary continuous cellulose articles
is in the range 0,2-20 dtex and preferably 0,9-2 dtex,
7. A process according to claim 1, characterized in that
the zero shear viscosity of the spinning solution in the
shaping channel is in the range 2 000-10 000 and
preferably 4 000-7 000 Pas.

8. A process according to claim 1, characterized in that
the relaxation time of the solution at 85 °C is in the
range 0,5-80 s and preferably 1-8 s.
9. A process according to claim 1-8, characterized in
that the elongation rate E D.a of the shaping in steps b)
and c) satisfies the mathematical expression

10. A process according to claim 1-6 and 8-9,
characterized in that the elongation rate is preferably
in the range 6-60. 1/s for spinning fibers and films.
11. A process according to claim 1-3 and 5-8,
characterized in that the elongation rate is preferably
in the range 20-100 1/s for spinning filament yarns.

12. A process for producing continuous shaped cellulose articles substantially as herein described and exemplified.


Documents:

909-chenp-2003-abstract.pdf

909-chenp-2003-claims filed.pdf

909-chenp-2003-claims granted.pdf

909-chenp-2003-correspondnece-others.pdf

909-chenp-2003-correspondnece-po.pdf

909-chenp-2003-description(complete)filed.pdf

909-chenp-2003-description(complete)granted.pdf

909-chenp-2003-form 1.pdf

909-chenp-2003-form 26.pdf

909-chenp-2003-form 3.pdf

909-chenp-2003-form 5.pdf

909-chenp-2003-other documents.pdf

909-chenp-2003-pct.pdf


Patent Number 212212
Indian Patent Application Number 909/CHENP/2003
PG Journal Number 02/2008
Publication Date 11-Jan-2008
Grant Date 26-Nov-2007
Date of Filing 10-Jun-2003
Name of Patentee THUERINGISCHES INSTITUT FUR TEXTIL-UND KUNSTSTOFF-FORSCHUNG E.V
Applicant Address Breitscheidstrasse 97, D-07407 Rudolstadt
Inventors:
# Inventor's Name Inventor's Address
1 MICHELS, Christoph Gabelsbergerstrasse 7 07407 Rudolstadt
PCT International Classification Number C08B 1/00
PCT International Application Number PCT/DE2001/004620
PCT International Filing date 2001-12-07
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 100 62 083.3 2000-12-13 Germany