WO1996020300A2

WO1996020300A2 - Spinning device

Info

Publication number: WO1996020300A2
Application number: PCT/AT1995/000229
Authority: WO
Inventors: Franz Schwenninger; Friedrich Ecker; Wilhelm Feilmair; Christoph Schrempf; Heinrich Firgo
Original assignee: Lenzing Aktiengesellschaft
Priority date: 1994-12-22
Filing date: 1995-11-27
Publication date: 1996-07-04
Also published as: AU4167596A; BR9506858A; EP0832995A3; TR199501659A2; HUT78008A; TW293040B; CZ288127B6; EP0746641B1; IL116292A0; BG100793A; CA2183627A1; MA23749A1; DE19581437D2; TR199501659A3; NO963481D0; FI963269A; MX9603562A; PL315840A1; GB9617016D0; CR5234A

Abstract

The invention relates to a spinning device for operating the wet/dry amino-oxide process with: a spinning nozzle having spinning apertures for extruding filaments; a blower device by means of which the extruded filaments can be cooled immediately after leaving the spinning apertures; a container of spinning bath liquid; a bundling unit fitted in the spinning bath liquid to bundle the extruded filaments; and an air gap defined as the distance between the spinning nozzle from the surface of the spinning bath liquid; in which: the bundling unit is at such a distance from the spinning nozzle that the angle (α) between the filaments to the perpendicular to the spinning bath liquid is 45° at the most and the relation 0.1 + .0051 « 0.7.d0.(h-1)/h is satisfied, in which d0 is the distance (in mm) between a spinning aperture and its neighbouring aperture in the spinning nozzle, h is the distance (in mm) between the bundling component and the spinning nozzle and 1 is the air gap (mm), where 0.4 mm « d0 « 2 mm and 0 mm < 1 < 60 mm.

Description

Spinning device

The invention relates to a spinning device for carrying out the amine oxide process according to the dry / wet spinning process with a spinneret which has spinning holes for extruding filaments, a container with spinning bath liquid, a bundling element which is provided in the spinning bath liquid for bundling the extruded filaments, and an air gap , which is defined as the distance of the spinneret to the surface of the spinning bath liquid.

The technique of dry / wet spinning is very generally that spinning mass by a molding tool, e.g. a spinneret, in a medium which does not precipitate for the spinning mass, e.g. Air or an inert gas is extruded, wherein if a spinneret is used, filaments are formed which are stretched in this medium and then passed into a spinning bath liquid (coagulation bath) in which the filaments coagulate.

The amine oxide process is generally understood to mean the production of cellulosic moldings using tertiary amine oxides. Cellulose is dissolved in a mixture of a tertiary amine oxide and water, the solution is shaped with a molding tool and passed through an aqueous precipitation bath in which the cellulose is precipitated. N-Methylmorpholine-N-oxide (NMMO) is primarily used as the amine oxide. Other amine oxides are e.g. in EP-A - 0 553 070. A method of making moldable cellulose solutions is e.g. known from EP-A-0 356 419.

The implementation of the amine oxide process using the dry / wet spinning process is known, for example, from DE-A-29 13 589. From WO 93/19230 and WO 95/04173 by the applicant an advantageous embodiment of the amine oxide process and a device for producing cellulosic fibers are known, according to which a solution of cellulose in a tertiary amine oxide is shaped in the warm state and the shaped solution by a gaseous medium ( Air) is introduced into the precipitation bath in order to precipitate the cellulose contained, the warm, shaped solution being cooled before being introduced into the precipitation bath. The cooling is carried out immediately after molding and preferably consists of blowing the cellulosic molding horizontally with air. The method according to the invention allows the cellulose solution to be spun with a high thread density without the spun threads sticking together after exiting the spinneret.

DD-A-218 121 also relates to a dry / wet spinning process for producing cellulosic fibers from cellulose solutions in tertiary amine oxides. According to this method, too, the cellulose solution is spun in an air gap, that is the distance between the spinneret and the surface of the spinning bath liquid, and is drawn into an aqueous precipitation bath. DD-A-218 121 mentions that the air gap can be shortened without adverse consequences for spinning safety if a polyalkylene ether is added to the cellulose solution before spinning. A small air gap is advantageous because the risk of the freshly extruded filaments sticking together is reduced.

EP-A-0 574 870 describes a dry / wet spinning process for processing solutions of cellulose in tertiary amine oxides and points out the advantage of a small air gap. With this spinning process it is possible, according to the description in the description of this patent application, to spin with a small air gap and with a high number of spinning bores per unit area. Despite these requirements, there should be no sticking of the Filaments are coming. It is recommended that the spun filaments come into contact with the spinning bath liquid in a spinning funnel. Spinning bath liquid is passed through this spinning funnel in cocurrent with the filaments. The axis of the spinning funnel is substantially perpendicular to the plane of the spinneret, and the flow of the spinning bath liquid is directed from top to bottom, the flow generally being caused by the free fall of the spinning bath liquid.

The warping or drawing of the freshly extruded filaments is achieved in accordance with EP-A-0 574 870 in such a way that the filaments are essentially accelerated to their take-off speed by the spinning bath liquid flowing through the spinning funnel.

This known spinning device has the disadvantage that the funnel tube of the spinning funnel, due to its relatively narrow diameter, places an upper limit on the filament bundle to be carried out with regard to its overall cross section, which is additionally set unsatisfactorily low for large-scale implementation of the method. According to the experience of the applicant of the present application, with a diameter of 6 mm, as is exemplified in EP-A-0 574 870, it is only possible to pass a bundle of filaments consisting of a maximum of 100 filaments through the funnel, as well Spin bath liquid must be transported through the funnel. This in turn means that when using such a spinning funnel, only one spinneret with a maximum of 100 spinning holes can be used.

If, on the other hand, a wide spinneret with tens of thousands of spinning holes is used, as is described, for example, in the applicant's Austrian patent AT-B 397.392, the funnel tube must be correspondingly larger, which in turn means that much more spinning bath liquid drains and must be circulated. This high throughput of spin bath liquid leads to turbulent flows in the spin bath, which disrupts the dry / wet spinning process.

GB-A-1,017,855 describes a device for dry / wet spinning of synthetic polymers. Here too, the use of a spinning funnel is recommended, through which spinning bath liquid is allowed to flow in cocurrent with the extruded fibers. The spinneret is about 0.5 cm above the surface of the spin bath.

The object of the invention is to provide a spinning device which makes it possible to carry out the amine oxide process according to the dry / wet spinning process in a simple manner and yet with good spinnability (high spinning reliability), with the highest possible maximum drawdown being possible with good spinnability (= at least possible titer) is to be understood before thread break. Another measure of the spinnability is the length of time during which one can spin without spinning errors that require technical assistance. Furthermore, even when using spinnerets with a high hole density, the freshly extruded filaments should not stick together in the air gap and the titer should be as constant as possible (small titer fluctuations).

The spinning device according to the invention for carrying out the amine oxide process according to the dry / wet spinning process with a spinneret, which spinning holes for extruding

Has filaments, a blowing device with which the extruded

Filaments can be cooled immediately after they have left the spinning holes, a container with spinning bath liquid, A bundling element, which is provided in the spinning bath liquid for bundling the extruded filaments, and an air gap, which is defined as the distance of the spinneret from the surface of the spinning bath liquid, is characterized in that the bundling element is at a distance from the spinneret such that the angle () that the filaments form perpendicular to the surface of the spinning bath liquid is a maximum of 45 ^* , and that the relationship

0.1 + 0.0051 <0.7.d _n . _______ ^u h

is satisfied in which d _{Q is} the distance (mm) between a spinning hole and its respective adjacent spinning hole on the spinneret, h is the distance (mm) of the bundling element to the spinneret, and 1 is the air gap (mm), where

0.4 mm <d _Q <2 mm, and 0 mm <1 <60 mm.

It has been found that the object of the invention can be achieved if the spinning device used is designed in such a way that the above two criteria (angle α maximum 45 ^* and the fulfillment of the above inequalities) are met. When using spinnerets with a high hole density, it is necessary to cool the freshly extruded filaments immediately after leaving the spinning holes. However, this cooling is already known to the person skilled in the art from the prior art (see, for example, WO 95/04173 by the applicant).

A preferred embodiment of the spinning device according to the invention is characterized in that the bundling element is designed as a deflection element which the filaments are not only bundled, but also redirected.

It has proven to be advantageous that the deflecting element is designed such that it does not rotate when the filaments are deflected. According to this embodiment, no rotatable roller or roller is therefore provided as the deflection element. This ensures that torn filaments are not wound on the deflecting element. This makes it easier to carry out the amine oxide process.

A further preferred embodiment of the spinning device according to the invention is characterized in that the angle α does not exceed 20 ". It has been shown that it is very important for the spinning safety in the dry / wet spinning process that the draft angle α in the air gap is as small as possible and preferably does not exceed 20 ^* , thus minimizing the risk of the filaments sticking in the space between the spinneret and the surface of the spinning bath and increasing the spinning safety.

The invention also relates to a spinning device for carrying out the amine oxide process by the dry / wet spinning process with a spinneret, which spinning holes for extruding

Has filaments, a blowing device with which the extruded

Filaments can be cooled immediately after they have left the spinning holes, a container with spinning bath liquid, a deflection element which is provided in the spinning bath liquid for bundling and deflecting the extruded filaments, and an air gap which is the distance from the spinneret to

Spin bath liquid is defined. which is characterized in that the deflecting element is designed such that it does not rotate when the filaments are deflected.

Another expedient embodiment of the spinning device according to the invention is that the spinneret has: an essentially rotationally symmetrical design

Nozzle body that has a feeder at its center

Has cooling gas, a feed for the cellulose solution, an annular spinning insert with spinning holes, and a baffle plate for directing the cooling gas flow onto the

Filaments that are extruded from the spinning holes so that the cooling gas flow is substantially perpendicular to the

Filaments meets.

In this way, it can be spun with an even higher hole density and at the same time effectively prevent the freshly extruded filaments from sticking in the air gap. Cooling an annular filament sheet by blowing with cooling air is known from WO 95/04173 by the applicant.

A further preferred embodiment of the spinning device according to the invention is that the container containing the spinning bath liquid is connected to a lifting device with which the container can be moved towards and away from the spinneret in the vertical direction, whereby the distance 1 is changed, and that the bundling element is arranged so that the distance h remains constant despite this movement.

With the drawing, which consists of Figures 1, 2 and 3, an embodiment of the invention is explained. The drawing shows a general representation of the dry / wet spinning process together with the quantities important for the relationship according to the invention. In FIG. 1, 1 denotes a container for holding spinning bath liquid, the surface of the spinning bath liquid being indicated by la. During the spinning process, spinning mass is extruded through the spinneret 3 and the extruded filaments 4, 5 are drawn off via the air gap 1 into the spinning bath liquid in which they coagulate. At the deflection element 2, which is a non-rotatable, cylindrical rod, the coagulated filaments are bundled, deflected and pulled off obliquely upwards. The distance between the underside of the spinneret 3 and the surface la of the spinning bath liquid is defined as the air gap 1. The angle defined above, which the filaments form perpendicular to the surface of the spinning bath liquid, is denoted by α.

The reference numeral 4 denotes a filament which comes from a spinning hole which is located on the outer edge of a circular ring formed by the spinning holes in the spinneret 3, i. is the radius (mm) of the circle, which limits the circular ring formed by the spinning holes to the outside. With d _Q the distance of this spinning hole to its neighboring spinning hole 5 is designated, whereby the distance between the respective centers of the two neighboring spinning holes is meant. h is the distance between the deflecting element 2 and the spinneret 7, and 1 is the air gap.

According to the embodiment described in FIG. 1, the container 1 stands on a lifting device (not shown) with which the container 1 moves vertically and the size of the air gap 1 can thereby be changed in a simple manner.

It has proven to be particularly advantageous not to attach the deflection element 2 to the container 1, but to provide that the container 1 can be moved and that the distance 4 remains constant at the same time. In this simple manner, the air gap 1 can be changed while keeping the distance h constant. This means a significant simplification when setting the spinning device according to the invention. Figures 2 and 3 show such embodiments of the spinning device according to the invention.

Figure 2 essentially shows the spinning device of Figure

I, the same parts being designated with the same reference numerals. The non-rotatable deflection element 2 is connected via a rigid arm 6 to a fixed element 7, which is not connected to the container 1, so that the element 7 is not moved when the container 1 is raised or lowered. The element 7 can be a wall, for example. Two positions of the container 1 are shown in FIG. 2, the lower position being indicated by dashed lines. The device for lifting and lowering the container 1 is not shown. It is clear from FIG. 2 that the air gap can be shortened or lengthened by raising and lowering the container 1, the distance h remaining the same at the same time.

Figure 3 shows a further embodiment of the spinning device according to the invention. In this embodiment, the deflection element 2 is anchored to the floor 8 by means of a rigid arm 9. The arm 9 protrudes through a corresponding opening

II, which is provided in the container 1. So that no liquid is lost from the container 1, a jacket 10 is provided for sealing, which is simply pushed together when the container 1 is lowered by means of a device, not shown.

The following examples 1, 2, 3 and 4 describe the invention in more detail, examples 1 and 2 documenting the influence of the angle α on the spinnability of cellulose solutions. Example 4 documents the advantageous effect of a non-rotatable deflection element on the spinnability. example 1

A spinning device was used which essentially corresponded to FIG. 1, but a spinning funnel according to EP-A-0 574 870 was used as the bundling element. The spinneret used was that described in WO 95/04173, the disclosure of which is incorporated by reference.

This previously known spinneret (number of holes: 3960; hole diameter: 100 μm; outer diameter of the nozzle (outermost row of holes) d .: 145 mm) has an essentially rotationally symmetrical nozzle body, which has a supply for cooling gas, a supply for cellulose solutions (13, 5% cellulose; temp .: 120 "C), an annular, deep-drawn spinning insert made of precious metal with spinning holes, which spinning insert is trough-shaped in cross-section, and has a baffle plate for directing a cooling gas stream onto cellulose filaments which are extruded from the spinning holes (output: 0.025 g / min), so that the cooling gas flow (24 m ³ / h) hits the extruded cellulose filaments essentially perpendicularly. The spinning holes are essentially uniformly spaced apart from one another in the spinning insert (hole-hole spacing d _Q : 1000 / im) had a length of 15 mm. The air in the air gap had a temperature of 24.5'C and a water hold 4.5 g water / kg air.

Several spinning tests were carried out, the distance h from the bundling point of the funnel (transition from the cylindrical tube to the actual funnel) to the spinneret surface being varied so that the air gap 1 remained constant so that the relationship

0.1 + 0.0051 <0.7.d _Q. t * ^1-1 ) (with 1 = 15 and d_ = 1000) was fulfilled. The maximum achievable end draw, that is the maximum pull-off speed of the filaments during thread breakage, was measured in each test. The results are shown in Table 1:

TABLE 1 h (mm) angle a final deduction (m / min) 240 16.8 ^* 43 190 20.9 ^* 42 140 27.4 ^* 42

90 38.8 ^* 41

70 46.0 ^* 29

40 61.1 ^* 0

Table 1 shows that up to an angle of approx. 40 ^*, no reduction in the final take-off speed and therefore no deterioration in the spinnability can be observed. From an angle of 45 ^* , however, the maximum final withdrawal speed is significantly reduced. At an angle of around 61 ^* , the solution is no longer spinnable.

Example 2

A spinning device was used which corresponded to FIG. 2, and the spinning nozzle used was again the one described schematically in WO 95/04173 (number of holes: 28,392; hole diameter: 100 μm; outer diameter of the nozzle (outermost row of holes)): 155 mm; hole-hole spacing d_: 500 μm).

The cellulose solution used had 13.5% cellulose and had a temperature of 120 ^* C. The output was 0.025 g / min. The air gap 1 had a length of 20 mm. The air in the air gap had a temperature of 12 ^* C and a water content of 5 g water / kg air.

The filaments were deflected on a cylindrical, non-rotatable rod 2 and pulled obliquely upwards out of the spinning bath.

With the air gap 1 remaining the distance h was again varied and, as in Example 1, the maximum final withdrawal speed and the angle α were determined. The results are shown in Table 2.

TABLE 2 h (mm) Angle α final deduction (m / min) 345 13 ^* 18 165 25 ^* 18 115 34 ^* 18 75 46 ^* 4

As can be seen from Table 2, when the angle α changes from 13 ^* to 34 ^*, there is no reduction in the maximum final withdrawal speed. However, if the angle α is increased to 46 ^* , the final take-off speed, ie the spinnability, is drastically reduced. If the distance h is shortened further (and thus the angle α is increased), the solution can no longer be spun.

Example 3

The same spinning device was used as described in Example 2, but the air gap 1 was set constant at 30 mm. The distance h was again varied. On the basis of the occurrence of spinning defects (filament tears, extreme sticking of the filaments to one another), the spinning security of the solution was characterized under the specified conditions.

A high level of spinning security is given if practically no spinning defects occur in a period of more than 15 minutes. If spinning errors occur in a period of 15 minutes or before, spinning on a technical scale is only possible with constant technical assistance.

As a result, the spinning safety is characterized by a time specification, the specification "> 15 min" in Table 3 below meaning that good spinnability (practically no spinning defects within 15 minutes) was given. An indication of e.g. "<10 min" means that massive spinning errors occur before 10 minutes after the start of spinning, which force the spinning to be interrupted.

TABLE 3 h (mm) Angle α Spin protection 345 13 ^* > 15 min 165 25 °> 15 min 115 34 ^* > 15 min 100 38 ^* 10-15 min 85 42 ^* <10 min

It can be seen from Table 3 that good spinnability is achieved up to a distance h of 115 mm. If h is chosen to be even smaller, the relationship established according to the invention is no longer satisfied and the spinnability deteriorates drastically. This is the case with the last two attempts. This deterioration in spinning behavior occurs in the present example at an angle α of well below 45 '.

Example 4

In a pilot plant for the production of cellulose fibers by the amine oxide process, the manner in which the filaments were deflected in the spinning bath was also investigated in numerous individual tests with the spinning device according to the invention.

Rotationally symmetrical, rotatable deflection elements of various designs (rolls with glass rods that had a smooth or a ribbed surface) were tested. In these experiments it was found time and again that as soon as the deflection element rotates about its own axis, filaments are wound up in the deflection roller within a short time. The cause of the winding is apparently that there are sometimes individual thread breaks in the spinning bath, which are caught by a rotating deflection roller, are carried by the deflection roller and lead to ever larger windings by carrying other filaments. The spun filaments are damaged because the filaments wound on the deflection roller have to be removed again by mechanical intervention, which leads to a deterioration in the end product.

It has been found that if a rotatable deflection roller is used, the spinning process must be interrupted in a period of less than 30 minutes in order to remove the fibers wound up on the deflection roller.

If, while maintaining the other parameters, the rotation of the deflecting element is prevented, for example by being rigidly supported, there is practically no winding more. It has been shown that in this way a continuous spinning process can be maintained for several hours. The use of rotatable deflection elements should therefore be avoided. In order to enable trouble-free operation, it is necessary to design all deflection elements as non-rotatably as possible.

Claims

Claims:

1. Spinning device for carrying out the amine oxide process according to the dry / wet spinning process with a spinneret which has spinning holes for extruding filaments, a blowing device with which the extruded filaments can be cooled immediately after they have left the spinning holes, a container with spinning bath liquid, a bundling element, which in the

Spin bath liquid for bundling the extruded

Filaments is provided, and an air gap, which is the distance from the spinneret to

Surface of the spinning bath liquid is defined,

characterized,

that the bundling element (2) is at such a distance from the spinneret (3) that the angle (α) which the filaments form perpendicular to the surface (la) of the spinning bath liquid is at most 45 ^* , and that the relationship

0.1 + 0.0051 <0.7.d _n .l ^h _Ü

is satisfied, in which d _{Q is} the distance (mm) between a spinning hole and its respective neighboring spinning hole on the spinneret (3), h is the distance (mm) of the bundling element (2) to the spinneret (3), and 1 the air gap (mm) is where 0.4 mm <d <2 mm, and 0 mm <1 <60 mm.

2. Spinning device according to claim 1, characterized in that the bundling element (2) is designed as a deflecting element (2) on which the filaments (4; 5) are not only bundled but also deflected.

3. Spinning device according to claim 2, characterized in that the deflecting element (2) is designed such that it does not rotate when the filaments (4; 5) are deflected.

4. Spinning device according to one of claims 1 to 3, characterized in that the angle (α) is at most 20 ^* .

Spinning device for carrying out the amine oxide process by the dry / wet spinning process with a spinneret which has spinning holes for extruding filaments, a blowing device with which the extruded filaments can be cooled immediately after they have left the spinning holes, a container with spinning bath liquid, a deflecting element which in the

Spin bath liquid is provided for bundling and deflecting the extruded filaments, and an air gap, which is the distance from the spinneret to

Spin bath liquid is defined. characterized in that the deflecting element (2) is designed such that it does not rotate when the filaments (4; 5) are deflected.

Spinning device according to one of claims 1 to 5, characterized in that the spinneret has: an essentially rotationally symmetrical nozzle body which has a supply for cooling gas in its center, a supply for the cellulose solution, an annular spinning insert with spinning holes, and a baffle plate for Directing the cooling gas stream onto the filaments that are extruded from the spinning holes so that the cooling gas stream hits the filaments substantially perpendicularly.

Spinning device according to one of Claims 1 to 6, characterized in that the container containing the spinning bath liquid is connected to a lifting device with which the container can be moved towards and away from the spinneret in the vertical direction, thereby changing the distance 1, and in that the bundling element is arranged so that the distance h remains constant despite this movement.