SK284686B6 - Spinning device - Google Patents

Abstract

Spinning device for carrying out the amino oxide process by the dry/wet spinning process comprising a spinneret (3) which have spinning apertures for extruding filaments (4, 5) immediately after they have left the spinning apertures, a container (1) containing spinning bath liquid and an air gap (L) which is defined as the distance of the spinneret (3) from the surface of the spinning bath liquid. Bundling element (2) is situated at a distance from the spinneret (3) which is such that the angle (alpha) which the filaments form with respect to the normal to the surface (1a) of the spinning bath liquid is 45° at the most and relation 0.1 + 0.005L <= 0.7 . d0 . (h-L)/h is satisfied, in which d0 is the distance (mm) between a spinning aperture and its neighbouring aperture on the spinneret (3), h is the distance (mm) of the bundling element (2) from the spinneret (3) and (L) is the air gap where 0.4 mm <= d0 <= 2 mm and 0 mm < L < 60 mm.

Description

Technical field

The present invention relates to a spinning apparatus for carrying out the amide oxide process according to a dry / wet spinning method with a spinneret having spinnerets for extruding filaments, a spinning bath liquid tank, a bundling element which is in the spin bath liquid for bundling extruded filaments. and an air gap, which is defined as the distance of the spinneret from the surface of the spin bath liquid.

BACKGROUND OF THE INVENTION

The dry / wet spinning technique generally consists in extruding a spinning mass through a molding tool, for example a spinneret, into a non-shrinking medium medium, for example air or an inert gas, whereby when the spinnerette is used, filaments are formed in the spinneret. during consolidation, this medium is stretched and then fed into a spin bath liquid (shrinkage bath) in which the pigments coagulate.

The amine oxide process is generally understood to mean the formation of cellulosic shaped bodies using a tertiary amine oxide. In this process, the cellulose is dissolved in a mixture of tertiary amine oxide and water, the solution is shaped by a shaping tool and passed through an aqueous precipitation bath in which the cellulose precipitates. N-methylmorpholine-N-oxide (NMMO) is primarily used as the amine oxide. Other amine oxides are described, for example, in EP-A-0 553 070. A method for producing ductile cellulose solutions is known, for example, from EP-AS-0 356 419.

An embodiment of the amine oxide process, dry / wet spinning, is known, for example, from DE-S-29 13 589.

WO 93/19230 and WO 95 / (04173) disclose a preferred embodiment of the amine oxide process and the cellulose fiber production apparatus according to which the cellulose solution is shaped in the tertiary amine oxide in a warm state and the shaped solution is fed through a gas medium (air) The cooling is carried out immediately after shaping and consists essentially in the horizontal blowing of the cellulosic body through air. the fiber density, without adhering the fiberized fibers after exiting the spinneret.

DD-AS-218 121 also relates to a dry / wet spinning process for the production of cellulose fibers from cellulose solutions in tertiary amine oxide. Also, according to this method, the cellulose solution is spun into the air gap, which is the distance between the spinneret and the surface of the spin bath liquid, when stretched and stretched into a water precipitation bath. DD-A-218 121 mentions that the air gap can be shortened without disadvantages for the safety of spinning if a polyalkylene ether is added to the cellulose solution prior to spinning. A small air gap is advantageous because the risk of sticking freshly extruded filaments is reduced.

EP-S-0 574 870 discloses a dry / wet spinning process for treating cellulose solutions in tertiary amine oxide and points out the advantage of a small air gap. In this way, it is possible to spin with a small air gap and with a large number of spinning holes per unit area. In spite of these data, the spinning process should not adhere to the filaments. It is recommended that the spinning filaments be contacted with the spin bath liquid in the spinneret. In a uniform flow with the filaments, the spin bath liquid is guided through the spinner funnel. The axis of the spinneret is substantially perpendicular to the plane of the spinneret, and the flow of liquid for the spinning bath is directed from top to bottom, the flow generally being generated by the free fall of liquid for the spinning bath.

According to EP-A-0 574 870, the elongation or stretching of the freshly extruded filaments is achieved in such a way that the filaments are accelerated to their draw-off speed by the spinning liquid flowing through the spinning funnel.

This previously known spinning device has the disadvantage that the spinning funnel tube, by virtue of its relatively small diameter, determines the filament bundle to be formed with respect to its overall cross-section an upper limit which is still set unsatisfactorily low for a highly technical embodiment of the method. Thus, in the experience of the applicant of the present application at a diameter of 6 mm, as for example disclosed in EP-AS 0 574 870, only the filament bundle consisting of a maximum of 100 filaments can be guided through the funnel, since liquid must also be transported through the funnel. for spinning bath. This in turn means that only a spinneret with a maximum of 100 spinnerets can be used with such a spinning funnel.

If, on the other hand, a wide spinnerette is used with a thousand spinneret holes, such as described in the applicant's Austrian patent AT-B 397.392, the funnel tube must be correspondingly larger, which in turn must drain and circulate much more spinning liquid. This large amount of spin bath liquid leads to turbulent flows in the spin bath, which disrupts the dry / wet spinning process.

GB-A-1,017,855 discloses a dry / wet spinning apparatus for synthetic polymers. It is also recommended here to use a spinner funnel to allow the spin bath liquid to flow in a uniform stream with the extruded fibers. The spinneret is located approximately 0.5 cm above the surface of the spin bath.

SUMMARY OF THE INVENTION

These drawbacks are largely eliminated by the spinning apparatus for performing the amine oxide process of the dry / wet spinning method comprising a spinneret having spinnerets for extruding filaments, a blower for cooling extruded filaments immediately after leaving the spinnerets, a bundling element for bundling extruded filaments in a spin bath liquid and an air gap, defined as the distance of the spinneret from the surface of the spin bath liquid, the principle being that the binder is positioned relative to the spinneret at a distance such that form filaments against the perpendicular to the surface of the water for the spinning bath is at most 45 ° and that the relationship (hl) is met

0,1 +0,005 L <= 0,7.d _o -—, where d ₀ is the distance (mm) between the spinning hole and its always adjacent spinning hole on the spinneret, h is the distance (mm) of the bunching element from the spinnerette , and L is an air gap, wherein

0.4 mm <= d ₀ <= 2 mm a

0 mm <L <60 mm.

When using spinnerets with a high orifice value, freshly extruded filaments need to be cooled immediately after leaving the spinnerets. However, this cooling is already known to the person skilled in the art (see for example WO 95/04173).

In a preferred embodiment of the spinning device according to the invention, the bundling element is designed as a return element on which the filaments are not only bundled but also inverted.

It has proven advantageous to design the return element so that it does not rotate when the filaments are reversed. According to this embodiment, the pulley or roller is not the return element. As a result, the interrupted filaments are not wound on the return element. This facilitates the implementation of 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 for the spinning safety of the dry / wet spinning process it is absolutely important that the draw-in angle and the air gap are as small as possible and in particular do not exceed 20 °. Thereby, the risk of sticking the filaments in the space between the spinneret and the surface of the spin bath can be minimized and the spinning safety increased.

In a further preferred embodiment of the spinning device, the spinneret is provided with a body formed substantially rotationally symmetrically having a cooling gas inlet, a cellulose solution inlet, a circular spinneret having spinneret holes, and an impingement plate to control the flow of cooling filament extruded filaments. from the spinning holes to reach the cooling gas stream perpendicular to the filaments.

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

Preferably, the reservoir containing the spin bath fluid is in communication with a lifting device for moving the reservoir vertically to the spinneret back and forth and for varying the distance, wherein the bundling element is arranged to provide a constant distance.

The spinning apparatus according to the invention allows the amine oxide process according to the dry / wet spinning method to be simple in apparatus and therefore feasible with good spinning (physical spinning safety), while good spinning means high, maximum achievable final withdrawal (= least possible titer) before breaking the fiber. Another measure for spinning is the amount of time it can be spinning without any spinning error that would require a technical support measure. Furthermore, when using spinning nozzles with high orifice density alone, the sticking of the freshly extruded filaments in the air gap should be avoided and as constant a titer as possible (noticeable titer variations) should be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS The invention is further elucidated with reference to the accompanying drawings, in which: FIG. 1, FIG. 2 and FIG. 3 show a general illustration of the dry / wet spinning process.

DETAILED DESCRIPTION OF THE INVENTION

In the spinning process, the spinning mass is extruded through the spinnerette 3, and the extruded filaments 45 are drawn through the air gap L into the spinning liquid in which they coagulate. On the bundle element 2, which is a non-rotatable, cylindrical rod, the coagulated filaments are bundled, inverted and obliquely drawn upwards. The air gap L is defined as the distance of the underside of the spinneret 3 from the surface 1a of the spin bath liquid. The defined angle formed by the filaments relative to the perpendicular to the spin bath surface is indicated by a.

The filament 4 originates from the spinning orifice located at the outer edge of the annulus formed by the spinning orifices in the spinneret 3, d1 being the radius (mm) of the circle that outwardly delimits the annulus formed by the spinning orifices. d ₀ denotes the distance of this spinning orifice to its adjacent spinning orifice, the distance between respective centers of two adjacent spinning orifices, h being the distance of the bundling element 2 from the spinneret 3 and L being the air gap.

According to the embodiment shown in FIG. 1, the reservoir 1 stands on a lifting device (not shown here) which can be moved vertically by the reservoir 1 and thus the size of the air gap L can be varied in a simple manner.

It has proven to be particularly advantageous if the bundling element 2 is not fixed to the container 1, but the container 1 can be moved and at the same time the distance h remains constant. In this simple manner, the air gap L can be varied while keeping the distance h constant. This means a considerable simplification in setting up the spinning device according to the invention. Fig. 2 and FIG. 3 show embodiments of such a type of spinning device according to the invention.

Fig. 2 essentially shows the spinning device of FIG. 1, the same parts being designated with the same reference numerals. The non-rotatable bundling element 2 is connected via a rigid arm 6 to a fixed element 7 which is not connected to the container 1, so that when the container 1 is raised or lowered, the element 7 does not move with it. For example, the element 7 may be a wall. In FIG. 2 shows two positions of the reservoir 1, the lower position being indicated by the dashed line. The device for lifting and lowering the reservoir 1 is not shown. FIG. 2, it is clear that by lifting and lowering the container 1, the air gap can be shortened or extended, while at the same time the distance h remains the same.

Fig. 3 shows a further embodiment of the spinning device according to the invention. In this embodiment, the bundling element 2 is anchored by means of a rigid arm 9 on the floor 8. The arm 9 protrudes by a corresponding opening 11, which is considered in the container 1. In order not to lose any liquid from the reservoir 1, a casing 10 is provided for sealing, which simply closes when the reservoir 1 is lowered by means of a device (not shown).

The following Examples 1, 2, 3 and 4 illustrate the invention in more detail, with Examples 1 and 2 illustrating the effect of angle and the spinability of cellulose solutions. Example 4 illustrates the advantageous effect of a non-rotatable restoring element on spinning.

Example 1

A spinning device substantially corresponding to FIG. 1, but using the spinning funnel of EP-A 0 574 870 as the bundling element. The spinning nozzle used is that described in WO 95/04173.

This previously known spinneret (number of holes: 3960, hole diameter 100 µm, outer diameter of nozzle (outer row of holes) d: 145 mm) has a nozzle body formed essentially rotationally symmetrically, having a cooling gas inlet, for cellulose solutions (13.5% cellulose, temperature 120 ° C), a round deep-grooved spinner made of tempered steel with spinning holes, where the spinneret is formed in a waffle cross-section, and an impingement plate for controlling the cooling gas flow to the cellulosic filaments extruded from the spinnerets (discharge: 0.025 g / min) so that the cooling gas stream (24 m ³ / h) reaches the extruded cellulose filaments substantially perpendicularly. The spinning orifices in the spinneret have a substantially uniform spacing between them (aperture-aperture d ₀ : 1000 pm). The air gap L was 15 mm long. The air in the air gap had a temperature of 24.5 ° C and a water content of 4.5 g water / kg air.

Several spinning experiments were carried out, with the same air gap L changing the distance h of the funnel tie point (transition from the cylindrical tube to the funnel itself) from the surface of the spinneret so that the relationship (h-1)

0.1 + 0.005 L <= 0.7d _o ........, h

(where L = 15 and d ₀ = 1000). In a further experiment, the maximum attainable end draw, i.e. the maximum draw speed of the filaments at fiber breakage, was measured. The results are shown in Table 1:

Table 1 h (mm) angle α (°) final draft (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

It can be seen from Table 1 that no reduction in the ultimate draw-off speed and thus no deterioration of the spinability can be observed up to an angle of about 40 ^° . However, from an angle of 45 ^° the maximum end draw speed decreases markedly. At an angle of approximately 61 ^° , the solution is no longer fiberizable.

Example 2

A spinning device corresponding to FIG. 2, and as the spinnerette, in turn, the one described schematically in WO 95/04173 (number of holes 28.392, hole diameter 100 pm, nozzle outer diameter (outer row of holes (di: 155 pm, hole-hole spacing d ₀₎ : 500 pm).

The cellulose solution used contained 13.5% cellulose and had a temperature of 120 ° C. The removal was 0.025 g / min. The air gap L was 20 mm long. 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 inverted on a cylindrical non-rotatable rod 2 and drawn obliquely upward from the spin bath.

At the same air gap L, the distance h was varied and, analogously to Example 1, the maximum end draw speed and angle α were determined. The results are shown in Table 2.

Table 2 h (m, m) angle α (°) final draft (m / min) 345 13 18 165 25 18 115 34 18 75 46 4

As can be seen in Table 2, there is no reduction in the maximum end draw speed when the angle α is changed from 13 ⁰ to 34 ⁰ . However, if the angle α increases to 46, the end draw speed, i.e., the spinning capacity, is drastically reduced. If the distance h is further reduced, the angle α is no longer spinning.

Example 3

The same fiberising apparatus as described in Example 2 was used, but the air gap L was set constant at 30 mm.

Again the distance h was changed. Due to the occurrence of spinning errors (tearing of the filaments, extreme bonding of the filaments together) the safety of spinning of the solution under predetermined conditions was characterized.

A high spinability is given if virtually no spinning error occurs in a time interval of more than 15 minutes. If more spinning errors occur within a time interval of 15 minutes or earlier, spinning on a technical scale is only possible with a permanent technical support measure.

Furthermore, spinning is characterized by a time stamp, wherein in the following Table 3, "> 15 min." Indicates that good spinning has been given (virtually no spinning errors within 15 minutes). For example, "<10 min." Means that, already 10 minutes after the start of spinning, there were large spinning errors that forced the spinning to be interrupted.

Table 3 h (mm) angle α (°) fiberizability 245 13 > 15 min. 165 25 > 15 min. 115 34 > 15 min. 100 38 10-15 min. 85 42 <10 min.

From Table 3 it can be seen that up to a distance h of 115 mm good spinning is given. However, if h is chosen even less, the relationship established according to the invention is no longer fulfilled, and the spinnability deteriorates drastically. This is the case with both last attempts. This deterioration of the spinning behavior in this case already occurs at an angle and well below 45 [deg.].

Example 4

In a pilot plant for the production of cellulose fibers according to the amine oxide process, in many individual experiments the spinning apparatus according to the invention was also investigated by the method of turning the filaments in the spin bath.

Rotary symmetrical rotary return members of various embodiments (glass rod pulleys having a smooth or ribbed surface) were tested. In these experiments, it has always been found that as soon as the return element is rotated about its own axis, the filaments are wound in a short time at the return roller. The reason for the winding is obviously that in the spinning bath there is sometimes a single tearing of the fibers, which are picked up by the rotating return roller itself, are guided together from the return roller and the coiling of other filaments leads to an increasing winding. In this case, the spinning filaments are damaged, since the filaments wound on the deflection roller must be removed by mechanical intervention, which leads to a deterioration of the end product.

It has been shown that the spinning procedure must be interrupted in a time interval of less than 30 minutes in order to remove the fibers wound on the spinning roller when using the rotating deflection roller.

Since, when the other parameters are removed, the rotation of the return element is prevented by being fixed, for example, virtually no winding takes place. It has been shown that in this way the continuous spinning process can be maintained for more than a few hours. The use of rotatable return elements must therefore be avoided. In order to enable trouble-free operation, it is necessary that all the return elements are preferably non-rotatable.

Claims (6)

PATENT CLAIMS 1. A spinning apparatus for carrying out the amine-oxide dry / wet spinning process comprising a spinneret having spinning holes for extruding filaments, a blowing device for cooling extruded filaments immediately after leaving the spinning holes, a spinning bath liquid tank, a bundling extruder in a fiber bundle a spin bath liquid and an air gap, defined as the distance of the spinneret from the surface of the spin bath liquid, characterized in that the bundle member (2) is positioned relative to the spinneret (3) at a distance such that the angle (α) form filaments (4,5) against the perpendicular to the surface (1a) of the spin bath liquid being at most 45 ° and that the relationship (h-1) is met 0,1 +0,005 L <- 0,7.d _o -—, where d _o is the distance (mm) between the spinning hole and its always adjacent spinning hole on the spinneret (3), h is the distance (mm) of the bundling element (2) from the spinneret (3) and (L) there is an air gap, wherein 0.4 mm <= d ₀ <= 2 mm a 0 mm <L <60 mm. Spinning device according to claim 1, characterized in that the bundling element (2) is a return element for bundling and inverting the filaments (4, 5). Spinning device according to claim 2, characterized in that the bundling element (2) is non-rotatable when the filaments (4, 5) are reversed. Spinning device according to one of claims 1 to 3, characterized in that the angle (α) is at most 20 °. Spinning device according to one of claims 1 to 4, characterized in that the spinnerette (3) is provided with a substantially rotationally symmetrical body having a cooling gas inlet, a cellulose solution inlet, a circular spinneret with spinnerets in its center. apertures, and an impingement plate for controlling the cooling gas flow to the filaments (4, 5) extruded from the spinning holes to engage a cooling gas flow perpendicular to the filaments (4, 5). Spinning device according to one of claims 1 to 5, characterized in that the tank (1) containing the spinning bath liquid is in connection with a lifting device for moving the container (1) in a vertical direction towards the spinnerette (3) back and forth and for varying the distance (L), wherein the bundling element (2) is arranged to provide a constant distance (h).