CN1132972C - Spinning device - Google Patents

Abstract

The invention relates to a spinning device for carrying out the amine oxide process according to the dry spinning/wet spinning process, which has: a spinneret with spinneret holes for extruding filaments; a blowing device that enables extrusion The filaments are cooled immediately after leaving the spinneret holes; a container with a spinning bath; a diverting element, which is placed in the spinning bath to bundle and divert the spun filaments; An air gap as a distance between the filament plate and the spinning bath surface; it is characterized in that the turning element (2) is designed so that it does not rotate when the filaments (4, 5) turn around.

Description

Spinning device

technical field

The invention relates to a spinning device for implementing an amine oxide process according to a dry spinning/wet spinning process. The spinning device has a spinneret with many spinneret holes for extruding filaments. The spinning device There is also a container for adorning spinning bath liquid and a converging part installed in the spinning bath liquid for bundling extruded filaments. In addition, there is an air gap defined as the distance between the spinneret and the spinning bath surface.

Background technique

Generally speaking, the dry spinning/wet spinning technology is that the spinning dope is extruded through a die such as a spinneret, and then enters a medium that makes the spinning dope not solidify, such as air or an inert gas, wherein A filament formed in the case of a spinneret. It is stretched in this medium, and then sent to the spinning bath (coagulation bath) to solidify.

The so-called amine oxide process refers to the application of tertiary amine oxides to produce cellulose molded bodies. Cellulose is first dissolved in a mixture of tertiary amine oxides and water, the solution is extruded through a die and passed through an aqueous coagulation bath in which the cellulose is coagulated. N-methylmorpholine N-oxide (NMMO) is used primarily as amine oxide. Other amine oxides are described, for example, in EP-A-0 553 070. A method for producing formable cellulose solutions is known, for example, from EP-A-0 356 419.

The implementation of the amine oxide process according to the dry spinning/wet spinning method is known, for example, from German patent DE-A-29 13 589.

A preferred embodiment of the amine oxide process and a plant for the production of cellulose fibers, i.e. cellulose in a tertiary amine oxide, are known from WO 93/19230 and WO 95/04173 of the applicant. The solution is formed while hot, the formed solution is passed through a gaseous medium (air) into the coagulation bath in order to coagulate the cellulose contained, the formed hot solution is allowed to cool before entering the coagulation bath. The cooling process is carried out immediately after forming, preferably by blowing the cellulose shaped body horizontally with air. According to the method of the present invention, the spinning of the cellulose solution can be carried out with a high filament density without causing the filaments to stick together after exiting the spinneret.

DD-A-218 121 also relates to a dry/wet spinning process for the production of cellulose fibers from cellulose solutions in tertiary amine oxides. In this process, the cellulose solution is spun in an air gap, ie in the space between the spinneret and the bath surface of the spinneret, stretched and introduced into an aqueous coagulation bath. In DD-A-218 121 it is pointed out that if polyalkylene ether is added to the cellulose solution before spinning, the air gap can be shortened, and there is no negative effect on spinning safety. Small air gaps are advantageous because the risk of sticking of the freshly extruded strands is reduced.

Introduced in EP-A-0 574 870 is a dry spinning/wet spinning process for processing cellulose solutions dissolved in tertiary amine oxides, and the advantage of utilizing small air gaps. With this spinning process, according to the description in the specification of the patent application, it is possible to spin with a higher number of spinneret holes per unit area in a small air gap. Although under this condition, filament sticking did not occur during spinning. For this purpose it is proposed that the contacting of the spun filaments with the spinning bath takes place in a spinning funnel. The spinning solution flows through the spinning funnel cocurrently with the filaments. The axis of the funnel is basically perpendicular to the plane of the spinneret, and the flow direction of the spinning bath is from top to bottom. This flow is generally produced by the free fall of the spinning bath.

According to EP-A-0 574 870, the freshly extruded filaments are drawn or drafted in such a way that the filaments are substantially accelerated by the spinning bath 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, is adjusted to an upper limit with regard to the overall cross-section of the thread bundle passing through. This upper limit, however, is set at an unsatisfactorily low level for an industrial scale implementation of the process. According to the experience of the applicant of the present application, when the diameter of the funnel tube is 6mm, just as the example that EP-A-0 574 870 gives, can only make the tow that is made up of 100 filaments at most pass through the funnel, because spinning The silk bath must also be conveyed by the funnel. This again shows that, if such a spinning funnel is used, only a spinneret with a maximum of 100 spinneret holes can be used.

On the other hand, if a large spinneret with thousands of spinneret holes is used, as described in the applicant's Austrian patent AT-B 397.392, the funnel tube must be enlarged accordingly, which necessitates further Multiple spinning bath streams pass through and circulate. This high spinning bath throughput leads to turbulent flow in the spinning bath, thus preventing the use of dry/wet spinning processes.

British Patent GB-A-1,017,855 describes an apparatus for the dry/wet spinning process of synthetic polymers. It is also recommended to use a spinning funnel and let the spinning bath flow through the funnel with the extruded filaments. The spinneret is located at a height of about 0.5 cm above the level of the spinning bath.

Contents of the invention

The task proposed by the present invention is to provide a spinning device that can implement the amine oxide process according to the dry spinning/wet spinning process. The equipment is simple but has good spinnability (high spinning safety), good spinnability Refers to the highest achievable final draw (lowest possible titer) before the filament breaks. Another measure of spinnability is the spinnability period, that is, the time during which no spinning defects that require technical assistance occur. Furthermore, the freshly extruded strands should be prevented from sticking in the air gap and should achieve as stable a titer as possible (slight titer deviations) even when using spinnerets with a high spinneret density.

The spinning unit of the present invention for carrying out the amine oxide process according to the dry spinning/wet spinning process, comprising: - a spinneret with spinneret holes for extruding filaments; - a blowing device enabling the extruded The filaments are cooled immediately after leaving the spinneret hole; - a container containing the spinning bath; - a converging unit, which is placed in the spinning bath and bundles the spun filaments; - a definite spinneret The air gap of the distance between the plate and the spinning bath surface;

The present invention is characterized in that: - the clustering part and the spinneret are at such a distance that the angle (α) formed by the filament and the perpendicular to the spinning bath surface is at most 45 ° and - the following relational expression is satisfied: $0.1+0.0051\≤0.7\·d0\&Center\; Dot;\frac{(h-l)}{h}$

In the formula, d0 represents the distance (mm) between a spinneret hole on the spinneret and its adjacent spinneret hole (mm); h is the distance (mm) between the bundled parts and the spinneret; l represents the air gap (mm), where

0.4mm≤d0≤2mm, and

0mm<1<60mm.

This shows that the object of the invention is solved in that the spinning device used is designed to satisfy the two above-mentioned criteria (angle α of at most 45° and the above-mentioned inequalities). When using a spinneret with a higher hole density, the freshly extruded filament needs to be cooled immediately after leaving the spinneret hole. This cooling is already known from the prior art for the specialist (for example referring to the applicant's WO 95/04173).

A preferred embodiment of the spinning device according to the invention is characterized in that the converging element is designed as a deflecting element, ie it not only constricts the thread strands but also guides the deflection of the filament bundle.

An obvious advantage of the diverting element design is that the element itself does not rotate when the filament is diverted. According to this embodiment, no rotating rollers or rollers are provided as deflecting elements. This ensures that broken strands do not wind up on the deflection element. These facilitate 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°. This is decisive for the spinning safety of the dry spinning/wet spinning process. The stretching angle α should be as small as possible in the air gap, preferably no more than 20°. This minimizes the risk of sticking of the strands in the space between the spinneret and the spinning bath surface and increases spinning safety.

The invention also relates to a spinning unit for performing the amine oxide process according to the dry spinning/wet spinning process, comprising: - a spinneret with spinneret holes for extruding filaments; a blowing device capable of The extruded filaments are cooled immediately after leaving the orifice; - a container for the spinning bath; - a deflecting element arranged in the spinning bath to bundle the spun filaments and deflect them, and - a Air gap, which determines the distance between the spinneret and the liquid level of the spinning bath;

The device is characterized in that the design of the steering element is such that the element does not follow the rotation when the yarn is turned.

According to another suitable configuration of the spinning device according to the invention, the spinneret has: - an essentially rotationally symmetrical spinneret body with an inlet for cooling gas in its center; - a cellulose solution a feed opening; - an annular spin insert with orifices; and - a baffle for controlling the cooling air flow to the filaments extruding from the orifices so that the cooling air flow is substantially vertical contact with the thread.

In this way, it is not only possible to spin with a higher hole density, but also to effectively prevent the freshly extruded filaments from sticking in the air gap. Cooling of endless tows by cooling air blowing is known from WO 95/04173 of the applicant.

According to another preferred form of the spinning device of the present invention, the container containing the spinning bath is connected to a lifting device, the container can move vertically with this lifting device, approaching and leaving the spinneret, Thus the air gap l is changed, but the cluster components are arranged such that although the containers move, the distance h remains constant.

Description of drawings

An embodiment of the invention is illustrated with reference to FIGS. 1 , 2 and 3 . The attached drawing shows a general dry spinning/wet spinning process including the main parameters relevant according to the invention.

Fig. 1 represents the view of the spinning device of the present invention;

Fig. 2 represents the spinning device of Fig. 1 of the present invention;

Figure 3 shows another embodiment of the invention.

Detailed ways

In Fig. 1, the container containing the spinning bath is indicated by 1, and the liquid level of the spinning bath is indicated by 1a. During the spinning process, the spinning dope is extruded through the spinneret 3 . The extruded strands 4, 5 are introduced into the spinning bath through the air gap 1 and solidify in the bath. The solidified filaments are bundled and diverted on a non-rotating round stick-shaped diverting element 2, and drawn obliquely upwards. The distance between the bottom of the spinneret 3 and the level 1a of the spinning bath is defined as the air gap l. The angle formed by the previously defined filament and the perpendicular to the spinning bath surface is denoted by α.

A thread emerging from a spinneret orifice, designated 4, is located on the spinneret plate 3 at the outermost edge of a ring of spinneret holes. d1 is the radius of the circumference, which defines the range of the ring domain formed by many spinneret holes. d0 denotes the distance between the spinneret orifice 5 and the adjacent spinneret orifice 5 , and here generally refers to the distance between the individual centers of two adjacent spinneret orifices. h represents the distance between the steering element 2 and the spinneret 3, and l represents the air gap.

According to the structure described in FIG. 1 , the container 1 is located on a lifting device (not shown in the figure). The container 1 moves vertically with the lifting device, so that the size of the air gap 1 can be changed very conveniently.

It is particularly advantageous that the deflection element 2 is not fastened to the container 1 but that the container 1 is movable while the distance h remains constant throughout. In this simple manner, the air gap l can be varied while keeping the distance h constant. This represents a considerable simplification of the adjustment of the spinning device according to the invention. Figures 2 and 3 show such embodiments of spinning devices according to the invention.

Fig. 2 basically shows the spinning apparatus of Fig. 1, and the same reference numerals are used for the same parts in the figure. The non-rotating diverting element 2 is connected by a rigid arm 6 to a fixed part 7, which is not connected to the container 1, so that when the container 1 is raised or lowered, the part 7 does not move with it. Part 7 may be, for example, a wall panel. Two positions of the container 1 are shown in FIG. 2 , the lower position being indicated by a dashed line. The means for raising and lowering the container 1 are not shown in the figures. It is clear from FIG. 2 that by raising and lowering the container 1 the air gap l can be shortened or lengthened, while the distance h remains constant.

FIG. 3 shows another embodiment of the spinning device according to the invention. In this embodiment, the deflection element 2 is fastened to the base plate 8 by means of a rigid arm 9 . The arms 9 project through corresponding openings provided in the container 1 . In order that the bath liquid does not escape from the container 1, a sealing jacket 10 is provided. When the container 1 is lowered by means of a device not shown, the jackets are simply moved together.

The present invention is further illustrated by the following examples 1, 2, 3 and 4, wherein examples 1 and 2 reveal the influence of angle α on the spinnability of cellulose solutions. Example 4 demonstrates the beneficial effect of such a non-rotatable diverting element on spinnability.

example 1:

Once used a kind of spinning device basically identical with Fig. 1, but adopt a spinning funnel by EP-A-0 574 870 as bundle part. The spinneret used was that described in WO 95/04173, the publication of which is cited here as a reference.

This known spinneret (number of holes: 3960; hole diameter: 100 μm; spinneret outer diameter (outermost hole arrangement) d1: 145mm) has a spinneret body formed substantially in rotational symmetry, in which In the center of the main body, there is a cooling gas inlet and a feeding port for cellulose solution (cellulose content is 13.5%, temperature is 120°C); there is also a ring-shaped deep-drawn spinning insert made of precious metal with many spinneret holes , the cross-section of the insert is in the shape of a circular groove, and there is also a baffle to control the cooling airflow (output is 0.025g/min) blown to the cellulose filaments extruded from the spinneret hole, so the cooling airflow (24 m ² /h) was blown substantially vertically onto the spun cellulose strands. The spinneret holes on the spinning insert are substantially uniformly spaced from one another (hole-to-hole spacing d0: 1000 μm). The air gap 1 has a length of 15 mm. The air temperature in the air gap is 24.5°C, and the water content is 4.5g/kg air.

Several spinning tests have been carried out. When the air gap l remains constant, the distance h between the funnel's cluster point (transition from the cylindrical tube to the funnel itself) and the surface of the spinneret is changed in this way to satisfy the relationship : $0.1+0.0051\&le;0.7\&Center\; Dot;d0\&CenterDot;\frac{(h-l)}{h}$

(where l=15 and d0=1000). Each test determined the maximum achievable final stretch, ie the maximum speed at which the filament could be stretched before fiber breakage. The results are listed in Table 1:

Table 1

  h(mm)         Angle α    Final Stretch (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

As can be seen from Table 1, up to an angle of about 40°, no slowdown in final drawing speed and deterioration in spinnability was observed. From an angle of 45°, the maximum final stretch speed slows down significantly. At approximately an angle of 61°, the solution can no longer be spun.

Example 2:

Once used a kind of spinning device that is equivalent to Fig. 2, spinneret also adopts that kind (hole number: 28,392; Hole diameter: 100 μ m; spinneret outer diameter (outermost Hole arrangement) d1: 155 mm; hole-hole spacing d0: 500 μm).

The cellulose solution used contained 13.5% cellulose and had a temperature of 120°C. The output is 0.025g/min. The air gap l is 20mm long. The air temperature in the air gap is 12°C, and its water content is 5g/kg air.

The filaments are deflected by a cylindrical non-rotatable roll 2 and drawn obliquely upwards from the spinning bath.

While the air gap l was kept constant, the gauge h was varied and similarly to Example 1, the maximum final stretching speed and angle α were determined. The results are listed in Table 2:

Table 2

  h(mm)   Angle α                                                                                                                                                           

345 13° 18

165 25° 18

115 34° 18

75 46° 4

It can be seen from Table 2 that the maximum final stretching speed does not slow down until the angle α varies from 13° to 34°. However, when the angle α is enlarged to 46°, the final drawing speed, that is, the spinnability, decreases significantly. Upon further shortening of the gauge h (and thus enlargement of α), the solution can no longer be spun.

Example 3:

The same spinning setup as described in Example 2 was used, but the air gap l was always adjusted at 30 mm. Change the gauge h again. The spinning safety of the solution under given conditions is indicated by the spinning faults that occur (filament breakage, extreme sticking of the filaments to each other).

Only when there are practically no spinning defects for more than 15 minutes does this indicate a high spinning safety. If spinning defects occur frequently within 15 minutes or before, industrial spinning production must be carried out with regular technical assistance measures.

Thereafter, the spinning safety is characterized by time, and thus the time expression ">15 minutes" in Table 3 means that the spinnability is good (actually no spinning defect occurs within 15 minutes). If the time is, for example, "<10 minutes", it indicates that a large number of spinning defects that force the spinning to be interrupted occurred within less than 10 minutes after the start of spinning.

table 3

  h(mm)   Angle α   Spinning Safety

345 13° ＞15 points

165 25° ＞15 points

115 34° ＞15 points

100 38° 10-15 minutes

85 42° ＜10 points

As can be seen from Table 3, the gauge h has good spinnability up to 115mm. If h is selected to be smaller, the relational formula listed according to the present invention can no longer be satisfied, and the spinnability will deteriorate sharply. This is what happened in the last two trials. In the above example, when the angle α is smaller than 45°, the spinning performance has been remarkably deteriorated.

Example 4:

In a pilot plant for the production of cellulose fibers according to the amine oxide process, a number of individual tests were carried out on the spinning apparatus according to the invention to investigate the manner and method of deflection of the filaments in the spinning bath.

Rotatable, rotationally symmetrical deflector elements (glass rod rollers with a smooth or ribbed surface) were tested in many different designs. In these tests, it was repeatedly determined that as soon as the deflecting element was rotated about its axis, the deflection rollers were wound up with thread within a very short time. The reason for the filament winding on the roll is obviously that individual broken fibers sometimes appear in the spinning bath, are collected and dragged by the rotatable deflection roller, and the winding on the roller is larger and larger due to the entrainment of other filaments. The spun sliver is then damaged, since the sliver wound on the deflection roll must be removed again with a mechanical intervention, thus resulting in a deterioration of the final product.

It has been shown here that the spinning process must be interrupted in less than 30 minutes using a rotatable deflection roll in order to remove fibers wound on the deflection roll.

If the other parameters are to be maintained, the rotation of the steering element must be prevented, for example if the element is mounted rigidly, so that no winding occurs in practice. In this way it was shown that a continuous spinning process can be maintained for many hours. Rotatable deflection elements should therefore be avoided. In order to be able to perform a satisfactory production run, all steering elements must be designed as non-rotatable as possible.

Claims (3)

1. Spinning unit for implementing the amine oxide process according to the dry spinning/wet spinning process, which has: - a spinneret with spinneret holes for extruding filaments; - a blowing device, which can make the extruded The filaments are cooled immediately after leaving the spinneret hole; - a container containing the spinning bath; - a diverting element, which is arranged in the spinning bath to bundle and divert the spun filaments; and - a fixed is the air gap between the spinneret and the spinning bath surface as a distance; It is characterized in that: the steering element (2) is designed such that it does not rotate itself when the yarn (4, 5) turns. 2. Spinning device according to claim 1, characterized in that the spinneret has: - a substantially rotationally symmetrical spinneret body with an inlet for cooling gas in its center; - a cellulose solution - an annular spin insert with orifices; and - a baffle to control the cooling air flow to the filaments extruding from the orifices so that the cooling air flow is substantially vertical contact with the thread. 3. The spinning device according to claim 1, wherein the container containing the spinning bath liquid is connected with a lifting device, and the container can move vertically with this lifting device, approaching the spinneret. and away, so that the air gap (1) is varied, while the deflecting element is arranged in such a way that the distance (h) between the deflecting element and the spinneret remains constant despite this lifting movement of the container.

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