Title of Invention

A PROCESS FOR CONTROLLING THE COMPOSITION OF A SOLUTION AND A DEVICE FOR PERFORMING THE PROCESS

Abstract The present invention relates to a method for producing cellulosed shaped bodies, (a) cellulose and an aqueous aminoxide are mixed, whereby a suspension is produced. (b) A cellulose solution is produced behavior of the produced cellulose solution is measured and the measured value is used for correcting the composition of the solution and (d) the cellulose solution is extruded through a gap of air and into an aqueous regenerating bath where said solution is coagulated to form shaped bodies which can go through additional treatment steps. The invention is characterized in that a second property of the produced cellulose solution is measured interposition of the solution is calculated by means of the measured values of both properties. The deviation from a desired composition is used for controlling the composition of the solution. The invention method enables to exactly control the composition of the spinning soluction.
Full Text The invention relates to a process for controlling the composition of solutions in the production of cellulosic shaped bodies, in which (a) cellulose and a water-containing amine oxide are mixed to form a suspension, (b) a cellulose solution is created from the suspension by vaporization of water, (c) a first property or physical behavior of the cellulose solution formed thereby is measured and the measured value is used to adjust the composition of the solution, and (d) the cellulose solution is extruded through an air gap into an aqueous regeneration bath where it is coagulated to form shaped bodies that are capable of undergoing further processing steps. The invention further relates to a device for carrying out this process with a slurrying apparatus equipped with metering devices, a dissolving and vaporizing arrangement connected to the slurrying apparatus and an extruding device connected to the dissolving and vaporizing arrangement by a conduit and having a regeneration bath attached downstream. Wherever the text of this application refers generally to a property for measurement of the cellulose solution, this should also be understood to include a physical behavior of the solution that is capable of being measured (measured variable)•
The properties of the cellulosic shaped bodies produced according to the amine oxide process, particularly the physical properties as textiles of the spun fibers and filaments, depend to a great extent on the composition of the spinning solution. It is therefore desirable for the achievement of optimal properties that the composition of the spinning solution be monitored and that variations be kept within narrow tolerances. From WO 94/28212, it is

known to take a sample from the spinning solution upstream from the extruding device and to measure its refractive index. In order to assure satisfactory extrusion products, the refractive index should be between 1.4890 and 1.4 91 at 60 °C. In addition to this discontinuous system of monitoring, a device for continuous measurement in the conduit, e.g. using a process refractometer, is also indicated. If the spinning solution presents a refractive index outside the refractive index cited, the feedstock for the premixer and/or the vaporization conditions must be reset.
The spinning solution is a ternary mixture of cellulose, amine oxide and water; therefore, its composition cannot be determined precisely by the measurement of only one property of the spinning solution. A number of solution compositions that fall within the solution area in the ternary system"s triangle plot can be allocated to one refractive index. It is therefore not possible to control the concentration of the spinning solution precisely on the basis of the refractive index alone. The fact that a specific solution compound does not fall within the indicated refractive index range anyway is also not addressed.
The object of the present invention is to provide a process for manufacturing cellulosic shaped bodies in accordance with the amine oxide process, wherein the composition of the spinning solution can be monitored precisely. In particular, the composition of the spinning solution is to be monitored precisely so that even small deviations from a predetermined target value can be used to correct the composition of the solution. In addition, a method for preparing cellulosic shaped bodies according to the amine oxide process is proposed, wherein the composition of the spinning solution is adj usted with the smallest possible delay or dead time, so that any fluctuations in the

composition are eliminated rapidly or maintained within
narrow limits. Finally, a device is also proposed for
performing the process, by means of which changes in the
spinning solution composition, e.g. due to changes in
composition of the mixing materials, can be eliminated
rapidly. Further advantages are explained in the following
detailed description,
This object is solved by the process according to the invention indicated in the introduction in that, in step (c) , a second property, which is different fjrom the first property of the spinning solution, is measured, ^he actual composition of the solution is calculated on the basis of the two measured values, and the deviation of the actual composition from a target composition is used to adjust the composition of the solution.
Unlike the known process as described in WO 94/28212, two properties of the spinning solution are m.easured, thus allowing the composition to be calculated precisely from the measured values. This requires that the two properties of the pure components, cellulose, amine oxide and water are known in part. If they are not known, they must be determined experimentally, if necessary also by extrapolation. The measurement of the two properties according to the invention yields the exact composition of the solution. Accordingly, in the event of even small deviations from a desired target composition in the solution, adjustments can be made to the dosages of the solution components for producing the solution, or to the operation forming the solution to compensate for the deviation. The process according to the invention thus allows of considerably more rigorous control of the solution composition than is possible if the refractive index alone is monitored and the adjustment is only activated after the value passes outside the predetermined tolerance range of the refractive index.

In the preferred embodiment of the process according to the invention, the two properties of the spinning solution are chosen from the relative permittivities, the electrical conductivity, the microwave intensity attenuation and speed, the refractive index, the density, the water content, and the ultrasonic speed. The refractive index and the density of the solution are particularly suitable for use as the two properties for measurement. The density can be measured either radiometrically or with a Coriolis force sensor. The water content can be determined by the Karl Fischer method.
In the preferred embodiment of the process according to the invention, the temperature of the cellulose solution is measured during or shortly before or after the two indicated properties are measured, and the measured values of the two solution properties or the physical behavior are adjusted and the measured values are adjusted on the basis of the measured temperature. Since the temperature of the spinning solution may vary, the measured values must be converted to the reference temperature for which the property values or behavior values of the spinning solution of the target composition are known, with which the measured values are to be compared. This reference temperature, to which the measured values must be converted, is, for example 50 °C or 60 °C.
At least one of the two properties of the spinning solution is preferably measured in-line. In-line measurements not only allow rapid calculation of the solution composition, but they also limit the safety hazard from the possible initiation of uncontrollable runaway reactions due to the tendency of the solution to decompose.
In one embodiment of the process according to the invention, the solution composition is adjusted in the dosing of the components described in step (a) above. For

example, if a variation is noted in the cellulose concentration of the spinning solution, it is necessary to make an alteration in the dosing system. The causes may be attributed to a change in the water content of the cellulose used, or in the solvent mixture N-methylmorpholine-N-oxide (NMMO)/ H2O .
In a further embodiment, the adjustment to the solution composition is made to the operating conditions in step (b). If measurements reveal a shift in the NMMO/ H2O ratio, this can be corrected in step (b), for example, by increasing or reducing the rate of water vaporization at this point.
Moreover, the device according to the invention described in the introduction also presents a solution to the object of the invention in that a measuring apparatus is disposed in the conduit between the dissolving and vaporizing arrangement and the extruding device for the purpose of measuring two different properties of the solution and constitutes part of at least one controlling circuit for controlling the composition of the spinning solution. The measuring apparatus in the conduit between solution production and solution extrusion transmits signals, such as for example the refractive index and the density of the solution, by means of which a change is effected in the correcting variables, e.g. the dosing rates for cellulose and/or solvent, or the rate of water vaporization in the dissolving arrangement. The measuring apparatus consists of two instruments for measuring the different solution properties, The measuring instruments may be connected in series or in parallel. They are disposed in the conduit and provide results of measurement with no time so that dead time in the controlling circuit, and thus also fluctuations in the solution composition, are minimized. The invention also extends to the o-line arrangement of the measurement apparatus.

The measurement apparatus preferably includes a" device for measuring the temperature of the solution and for compensating for the measured values of the indicated measuring instruments. In this way, the measurement apparatus returns measured values for both properties that have already been adjusted to compensate for temperature, so that these values can be compared with the property values of the spinning solution having the target composition with respect to a predetermined temperature.
The purposes of the invention are served if the measurement apparatus, together with a microprocessor and the metering devices or the dissolving and vaporizing arrangement, together form at least one control circuit. In such event, correcting variables may be, for example, rhe dosing rates of the metering devices or the rate of water vaporization in the dissolving arrangement.
In the following, the invention will be explained in detail with reference to the drawing and a number of experiments.
The only figure shows the schematic flow diagram of an embodiment of the device according to the invention.
Water-containing cellulose and an NMMO/H2O mixture are introduced into a continuous slurrying apparatus 2 through a metering system 1. Apparatus 2 may be a inultishaft apparatus as described in DE-C 198 37 210.6. A dissolving arrangement 3 is connected downstream of apparatus 2, wherein the suspension formed in 2 is transformed into a solution by the application of heat and negative pressure to vaporize the water. A suitable process for this purpose is known from DE-A 44 41 468.8^ An extrusion tool 4 is connected to dissolving arrangement 3 by means of a conduit 8. The spinning solution is extruded by the extruding tool 4 across an air gap and into a regeneration bath 5. Depending on the type and design of the extrusion tool 4

and the subsequent operations, films, fibers, filaments or other shaped bodies may be produced. The shaped body 6 obtained thereby is passed through a discharging device 7 to subsequent treatment steps such as washing out the amine oxide, secondary treatment, cutting, drying.
The invention provides for the disposition of a measuring apparatus 9-11 in conduit 8 between the dissolving arrangement 3 and the extrusion tool 4. This consists of a measuring instrument 9 for measuring a first property of the solution, a measuring instrument 10 for measuring a second property different from the first property, and an instrument 11 for measuring the temperature of the spinning solution in conduit 8 between measuring instruments 9 and 10. As is shown, measuring instruments 9 and 10 are disposed consecutively in the flow. Measuring instruments 9 and 10 transmit signals to microprocessor 12 that are already corrected on the basis of the temperature measurements provided by instrument 11. From the signals it receives from measuring instruments 9 and 10, microprocessor 12 calculates the actual composition of the solution in conduit 8, derives the deviation from the preset target composition of the spinning solution and, from this deviation, calculates the correcting variables for metering devices 1^, l"^ and/or the operating conditions for dissolving arrangement 3. The correcting commands from microprocessor 12 are transmitted across one of signal circuits 13, 14, 15 or other signal circuits to the adjusting mechanisms concerned. Thus is demonstrated that, if the solution composition in conduit 8 deviates from the target value, the control mechanism, particularly the direct temperature compensation, according to the invention of the two measured values, allovjs for rapid correction, particularly since a sample does not have to be withdrawn in order for the temperature adjustment to be made,

Accordingly the present invention provides a process for controlling the composition of solution(s) in the production of cellulosic shaped bodies, comprising,
(a) mixing cellulose pulp and a water-containing aminoxide, to form a
suspension,
(b) forming a cellulose solution from the suspension by evaporation of water,
(c) measuring a first property or physical behaviour of the formed cellulose solution, and using the measured value for a correction of the composition of the solution, and
(d) extruding the cellulose solution through an air gap into an aqueous
precipitation bath where it is coagulated to form shaped bodies, that are capable of
undergoing flirther processing steps,
characterized in that,
in step (c), a second property of the formed cellulose solution, which is different from the first property, is measured, the actual composition of the solution is calculated from the measured values of those properties, and their deviation from a reference composition is used to adjust the composition of the solution, and furthermore the first and second properties of the cellulose solution are selected from the group consisting of relative permittivity, inductive conductivity, microwave absorption, refractive index, density, water content and ulfrasonic speed.
Accordingly the present invention also provides a device for performing the process according to any of the claims 1 to 5, comprising a mixing apparatus (2) equipped with metering elements (l^ l""), dissolving and evaporating device (3) connected to the mixing-apparatus (2) and an extrusion device (4) connected via line (8) with the dissolving and evaporation device (3), comprising a downsfream precipitation bath (5), characterized in that, the measuring device (9-11) is arranged in the line (8) for measuring two different properties of the solution selected from the group consisting of relative permittivity, inductive conductivity, microwave absorbtion, refractive index, density, water content and ultrasonic speed; which is a part of at least one regulating circuit for adjusting the composition of the cellulose solution.

Experiment 1
A measurement apparatus consisting of an RIS 60-3 radiation process refractometer manufactured by Risens GmbH, Jena, and an LB 386 radiometric densitometer manufactured by EG & G Berthold, Bad Wildbad, were built into the spinning solution conduit directly downstream of the dissolving apparatus in a continuously running installation for spinning Lyocell batch fibers corresponding to the Figure. Measurements of the refractive index and rhe density were adjusted to reflect a temperature of 50 "C in each case. From the measured values thus obtained, the percentage composition of the spinning solution was calculated. Directly after the measurement apparatus, a sample was withdrawn from the conduit through a nozzle for removing samples and tested for cellulose content (precipitation method) and water content (Karl Fischer titration} . The calculated values for the composition obtained therefrom an the values for cellulose and water determined by analysis are shown in the table. A good correspondence is revealed between the composition as calculated from the two measured properties, and the composition determined by analysis.
Experiment 2
The starting conditions were the same as for experiment 1. However, the vaporization conditions were then modified in dissolving arrangement 3 such that the water was vaporized more vigorously. To this end, the vacuum in the dissolving arrangement was increased while the temperature profile and the ratio cellulose/NMM0/H20 in the slurry were kept constant. The measured values for the properties obtained from the spinning solution, the values for cellulose, NMMO and water content derived therefrom, and the water and cellulose -content values determined by analysis are shown in the table. This shows that the change to the vaporization conditions is reflected not only in the values

obtained by direct analysis, but also in the data calculated from the solution properties.
Experiment 3
Beginning with the conditions established for experiment 2, and under constant conditions in the dissolving arrangement, the parameters for slurry preparation were temporarily changed such that the proportion of cellulose in the cellulose/NMMO/HiO ratio was increased. The ratios that existed at the outlet from the dissolving arrangement after 35, 4 5 and 50 minutes were determined by direct analysis and by the percentage content as calculated on the basis of the properties measurements from the measurement apparatus as in experiment 1. These results are listed in rows 3a, 3b, 3c in the table. From the data presented, it is clear that temporary changes in the composition of the spinning solution can be calculated very precisely on the basis of measurements of the two solution properties.
The results of experimentation indicate that the solution composition can be calculated with extremely high accuracy from the measured values of two properties of the spinning solution, so that close control of the composition of the spinning solution is possible. Since the calculated values are available with practically no delay, the process enables finer tolerances in the composition and correspondingly reduced fluctuations in the physical properties of the shaped body formed therefrom.






WE CLAIM:
1. A process for controlling the composition of solution(s) in the production of
cellulosic shaped bodies, comprising,
(a) mixing cellulose pulp and a water-containing aminoxide, to form a
suspension,
(b) forming a cellulose solution from the suspension by evaporation of water,
(c) measuring a first property or physical behaviour of the formed cellulose solution, and using the measured value for a correction of the composition of the solution, and
(d) extruding the cellulose solution through an air gap into an aqueous
precipitation bath where it is coagulated to form shaped bodies, that are capable of
undergoing further processing steps,
characterized in that,
in step (c), a second property of the formed cellulose solution, which is different from the first property, is measured, the actual composition of the solution is calculated from the measured values of those properties, and their deviation from a reference composition is used to adjust the composition of the solution, and furthermore the first and second properties of the cellulose solution are selected from the group consisting of relative permittivity, inductive conductivity, microwave absorption, refractive index, density, water content and ultrasonic speed.
2. The process according to claim 1, wherein the temperature of the cellulose solution is measured during or shortly before or after the measurement of the first and second properties and the measured values of the first and second properties are adjusted on the basis of the measured temperature.
3. The process according any of the claims 1 to 2, wherein at least one of said both properties is measured in-line.

4. The process according any of the claims 1 to 3, wherein the solution composition is adjusted by intervention in the dosing of the suspension components of step (a).
5. The process according to any of the claims I to 4, wherein the solution composition is adjusted by intervention in the operating conditions of step (b).
6. A device for performing the process according to any of the claims 1 to 5, comprising a mixing apparatus (2) equipped with metering elements (la, lb), dissolving and evaporating device (3) connected to the mixing-apparatus (2) and an extrusion device (4) connected via line (8) with the dissolving and evaporation device (3), comprising a downstream precipitation bath (5), characterized in that, the measuring device (9-11) is arranged in the line (8) for measuring two different properties of the solution selected from the group consisting of relative permittivity, inductive conductivity, microwave absorbtion, refractive index, density, water content and ultrasonic speed; which is a part of at least one regulating circuit for adjusting the composition of the cellulose solution.
7. The device according to claim 6, wherein the measuring device comprises two devices (9, 10) for measuring different solution properties.
8. The device according to claim 7, wherein the measuring device comprises a temperature measuring instrument (11) for measuring the temperature of the solution and to compensate for temperature in the measured values of measuring devices (9, 10).
9. The device according to any of the claims 6 to 8, wherein the measuring device (9-11), together with a microprocessor (12) and the metering elements (la, lb) or the dissolving and evaporating device (3), form a controlling circuit.

10. A process for controlling the composition of solution in the production of
cellulosic shaped bodies, substantially as hereinabove described and illustrated with
reference to the accompanying drawing.
11. A device for performing the process, substantially as hereinabove described
and illustrated with reference to the accompanying drawing.

Documents:

in-pct-2002-0257-che abstract.pdf

in-pct-2002-0257-che assignment.pdf

in-pct-2002-0257-che claims duplicate.pdf

in-pct-2002-0257-che claims.pdf

in-pct-2002-0257-che correspondence others.pdf

in-pct-2002-0257-che correspondence po.pdf

in-pct-2002-0257-che description (complete) duplicate.pdf

in-pct-2002-0257-che description (complete).pdf

in-pct-2002-0257-che drawings.pdf

in-pct-2002-0257-che form-1.pdf

in-pct-2002-0257-che form-19.pdf

in-pct-2002-0257-che form-26.pdf

in-pct-2002-0257-che form-3.pdf

in-pct-2002-0257-che form-4.pdf

in-pct-2002-0257-che form-5.pdf

in-pct-2002-0257-che form-6.pdf

in-pct-2002-0257-che pct.pdf

in-pct-2002-0257-che petition.pdf


Patent Number 202415
Indian Patent Application Number IN/PCT/2002/257/CHE
PG Journal Number 05/2007
Publication Date 02-Feb-2007
Grant Date 09-Oct-2006
Date of Filing 18-Feb-2002
Name of Patentee M/S. ZIMMER AKTIENGESELLSCHAFT
Applicant Address BORSIGALLEE 1, D-60388 FRANKFURT AM MAIN,
Inventors:
# Inventor's Name Inventor's Address
1 MEYER, WILHELM UNTERPEILIPP-ORTSSTRASSE 1, 07407 RUDOLSTADT,
2 MAINZER ALTHOF, TANJA STADTSCHREIBEREI 10, 63571 GENHAUSEN,
3 NIEMZ, FRANK-GUNTER AN DER BRUCKE 19, 07407 RUDOLSTADST,
PCT International Classification Number D01F 2/00
PCT International Application Number PCT/DE00/03410
PCT International Filing date 2000-09-29
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 19947910.0 1999-10-06 Denmark
2 19949726.5 1999-10-15 Denmark