CN218059316U

CN218059316U - Apparatus for producing cellulose threads from a solution of cellulose in a tertiary amine-oxide

Info

Publication number: CN218059316U
Application number: CN202220096997.5U
Authority: CN
Inventors: O·汉曼
Original assignee: Lenzing AG
Current assignee: Lenzing AG
Priority date: 2022-01-14
Filing date: 2022-01-14
Publication date: 2022-12-16
Anticipated expiration: 2032-01-14

Abstract

The present invention relates to an apparatus for manufacturing cellulose shaped bodies for manufacturing cellulose threads from a solution of cellulose in a tertiary amine oxide, the apparatus comprising a spinneret with spinning orifices, and wherein a.immediately below the spinning orifices a feed device for cooling gas is provided for cooling the cellulose threads, b.the spinning orifices of the spinneret are arranged in a ring, c.the feed device for cooling gas is provided in the center of the ring, which is formed by the arrangement of the spinning orifices, d.a further feed device for cooling gas is provided, which is provided outside the ring formed by the arrangement of the spinning orifices, and in the flow direction a gas flow control unit is installed in front of the feed device, which is controlled by a gas flow control system.

Description

Apparatus for producing cellulose threads from a solution of cellulose in a tertiary amine-oxide

Technical Field

The invention relates to a device for carrying out a method for producing cellulose moulded bodies, wherein a solution of cellulose in a tertiary amine oxide is moulded in the hot state, and the moulded solution is introduced into a coagulation bath in order to coagulate the contained cellulose.

Background

It is known from US2179181 that tertiary amine oxides are capable of dissolving cellulose, from which cellulose shaped bodies can be obtained by coagulation. A process for preparing such solutions is known, for example, from EP-A-0 356 419. According to this publication, a cellulose suspension is first prepared in an aqueous tertiary amine-oxide. The amine oxide contains up to 40% by weight of water. The aqueous cellulose suspension is heated and the water is removed under reduced pressure until the cellulose becomes a solution. The method is carried out in a specially developed stirring apparatus which can be evacuated.

A method of the type described at the outset is known from DE-A2 844 163 and DD-A218. For the production of cellulose fibres or cellulose films, an air space or air gap is arranged between the spinneret and the coagulation bath in order to achieve the drawing-off at the nozzle (die). This drawing is necessary because it becomes very difficult to draw the fiber after the shaped spinning solution is contacted with the coagulation bath containing water. The fiber structure produced in the air gap is fixed in a coagulation bath.

However, there is a risk in the air gap that: the individual fibers that have not yet coagulated will stick together or will fuse together due to their extremely high viscosity, thus making spinning of the fibers impossible. Of course, the longer the gap (air space) between the nozzle plate (die plate) and the surface of the coagulation bath, the greater the risk of such sticking together. On the other hand, a long gap may be advantageous because the orientation of the cellulose molecules requires a certain time. In order to minimize this risk of sticking together when large air gaps are used, the hole density in the spinneret must be reduced, which in turn adversely affects the economics of the spinning process.

While the use of a short air gap does allow spinning with a high hole density, it also compromises the reliability of the spinning process because the liquid from the coagulation bath reaches the spinning bore or the exit side of the spinning hole due to the capillary action of the filaments. As a result, the formed but still fluid fibre material does not withstand being drawn, i.e. does not reach the desired fibre thickness. At the same time, it can be shown that the textile value with respect to the strength and elongation of the fibers is hardly influenced by the shortened dwell time in the air gap.

In DD-a 218, it is provided that the length of the drawing gap on the die can be shortened by adding a polyalkylene ether, in particular polyethylene glycol, to the spinning solution, while the risk of individual fibers sticking together is correspondingly reduced, without any influence on the spinning reliability or on the fiber strength. The extreme viscosity of the spun fibers and the overcoming of this problem are also mentioned in DE-A2 844 163, in which, among other things, it is proposed to spray the fibers in the air gap with a liquid that does not dissolve the cellulose.

Tests have shown that not all proposed solutions are satisfactory in terms of the achievable spinning fibre density or in terms of the influence on the textile properties of the cellulose fibres. According to DE-A2 844 163, the distance between the spinneret and the surface of the coagulation bath is 270mm, but this obviously only allows about 0.0046 fibres/mm ² Spun fiber density of (corresponding to 0.0046 holes/mm in the spinneret) ² Spinning hole density of). Large scale spinning using such small pore densities is not conceivable. To do this, it is necessary to use a porous material having a pore/mm of greater than 0.1 ² The hole density of (a). Such a spinneret is described, for example, in austrian patent application a 2724/89.

Disclosure of Invention

The invention is now explicitly described here, which relates to the problem of improving the method mentioned at the outset by means of a suitable apparatus such that it allows the viscosity of the freshly extruded cellulose shaped body to be reduced without the need to add any type of additive to the spinning material and without the need to spray the surface of the shaped body with a coagulant. Especially, the utility model discloses can solve following problem: a method for producing cellulose fibres is provided, in which a compact fibre bundle can be spun by using a spinneret with a high hole density, which compact fibre bundle is guided through a large air gap to a coagulation bath in order to better control the textile properties of the spun fibres.

Despite such a compact fiber bundle, there should be no adhesion between the individual fibers despite the large air gaps.

The device according to the invention is characterized in that it makes it possible to cool the hot formed spinning solution first and then to bring this formed spinning solution into contact with the coagulation bath, whereby cooling takes place immediately after forming. The best way to cool the forming solution is to expose it to a stream of air.

The use of a gas stream substantially perpendicular to the spinning direction has proven particularly valuable when using spinnerets for the production of cellulose fibres by shaping a cellulose solution. Surprisingly, it has been found that the above-mentioned problem of blocking can be overcome in a simple manner, wherein the freshly spun fibers are exposed to an air stream, for example. Even a simple blowing against the fiber bundle with a fan ensures: can be used with up to 0.7 holes/mm ² And an air gap of up to 70mm length can be selected without any blocking of the individual fibres occurring in the air gap.

The apparatus according to the invention is also suitable for the preparation of cellulose films, wherein the cellulose solution is guided through a film forming apparatus, which apparatus is characterized in that the direction of film formation is substantially perpendicular to the gas flow.

When using spinnerets with still higher hole densities, the air flow distribution provided by the fan is no longer sufficient to ensure uniform cooling of the entire fiber bundle. In this case, a preferred embodiment of the apparatus according to the invention comprises means for exposing the hot forming solution to at least two gas flows, wherein these said gas flows are preferably applied to opposite sides of the forming solution.

One embodiment of this variant of the apparatus according to the invention for producing cellulose fibres comprises a device for conducting a hot cellulose solution through a spinning die, which device has a multiplicity of spinning orifices which are arranged substantially annularly, wherein the hot forming solution which emerges as spun fibres is exposed to two gas streams such that one gas stream is directed radially to the outside and the other gas stream is directed radially to the inside.

In this way, the cooling effect can be increased, so that a gap of at least 50mm can be guided with at most 1.4 fibers/mm ² Without the individual fibers sticking together.

The amount of heat removed from the hot forming solution during the cooling process is especially at least 20KJ/Kg solution, preferably between 20KJ/Kg solution and 350KJ/Kg solution, possibly even more.

The invention also relates to an apparatus for preparing cellulose fibres from a solution of cellulose in a tertiary amine-oxide, wherein the apparatus comprises a spinneret with spinning orifices. According to the utility model discloses a characterized in that, is close to the spinning hole in the low reaches of spinning hole and sets up the entry that is used for cooling gas, and this entry is used for cooling the cellulose fibre.

A particular embodiment of the apparatus according to the invention comprises a substantially annularly arranged spinning orifice in the spinneret, the apparatus having an inlet for cooling gas, which inlet is arranged in the center of the ring formed by the spinning orifice.

For uniform cooling from a sheet having more than 0.7 holes/mm ² The very dense fiber bundle extruded by the spinneret with the hole density of (a) has proven to be advantageous if a further cooling gas flow is provided which is guided onto the fiber bundle from the outside. The configuration of the apparatus according to the invention thus shows a further inlet for cooling gas, which is positioned outside the annular spinneret. In this case, the annular fiber bundle is exposed to the cooling gas not only on the inner side thereof but also on the outer side thereof. It has been shown that the cooling effect is significantly improved in this way.

However, applying multiple air streams on different sides of the same freshly extruded fiber bundle can cause severe disturbances in the uniformity and direction of movement of the fiber bundle. Some (or even many) of the individual fibers of the fiber bundle may stick together or may deviate from their original orientation. This may lead to spinning failure or even failure of the entire spinneret. Surprisingly, this problem can be solved by a gas flow control unit, which is mounted in the flow direction in front of the gas flow feed, which is controlled by a gas flow control system.

A flow device or baffle for homogenizing the flow of the cooling gas can be arranged in the inlet for the cooling gas, which is located in the center of the annular spinneret.

Another embodiment of the apparatus according to the invention comprises spinning orifices arranged in groups in the spinneret.

Drawings

The device according to the invention is further elucidated by means of the drawing, in which,

fig. 1 schematically shows a preferred embodiment of an apparatus for producing cellulose fibres according to the invention;

fig. 2 shows another preferred embodiment of the device according to the invention;

fig. 3 shows another preferred embodiment of the device according to the invention;

fig. 4a shows another preferred embodiment of the device according to the invention;

fig. 4b shows a bottom view of the spinneret plate.

Detailed Description

In fig. 1, a heatable spinning plate 1 is shown (heating device not shown), to which spinning material 3, i.e. a hot cellulose solution having a temperature of approximately 100 ℃, is supplied via a supply line 2. The pump 4 is used for metering the spinning material and for adjusting the pressure required for extrusion. The fiber bundle 5 extruded from the spinneret 1 through the spinning orifice 16 is cooled by means of an inert gas 6, preferably air, which is guided through a gas nozzle 7 onto the fiber bundle 5 leaving the spinneret 1. By means of this gas flow, it is possible to use spinnerets with a high pore density, without the spun fibers sticking together during the spinning process.

The fiber bundle 5 passes through a gas gap, which is defined as the distance between the spinneret 1 and the surface of the coagulation bath 8, then enters the coagulation bath 8, is collected together by guide rollers 9 and is drawn off. According to the invention, the blowing-in of gas and the cooling of the fiber bundle respectively enable the use of relatively long gas gaps, so that there is sufficient time for the orientation of the cellulose molecules to take place during the drawing of the fibers. The drawing is achieved by: the fiber bundle 5 is drawn off by means of a roller 9 at a greater speed than the fiber bundle leaving the spinneret 1.

The gas nozzles 7 surround the fiber bundle 5 in a ring shape and can either be attached directly to the spinneret 1 or can form a specially constructed unit which is attached to the spinneret 1 again. Of course, the transfer of heat from the hot spinning material 3 in the spinneret 1 to the cooling gas 6 should be prevented as far as possible, which can easily be achieved by suitable insulation structures. In order to achieve the effect according to the invention it is essential that the cooling gas flow is directed onto the fibre bundle 5 just leaving the spinneret 1, preferably in a plane substantially parallel to the plane formed by the spinning orifices 16.

Fig. 2, 3 and 4 show schematically further embodiments of the spinning device according to the invention shown in fig. 1, comprising a spinneret and a cooling gas nozzle. By means of these embodiments, even denser fiber bundles can be processed, i.e. spinnerets with still higher hole densities can be used.

Fig. 2 and 3 show a cross section of an annular, heatable (heating means not shown) spinning plate 1', 1 ″ and a device for blowing in gas, which comprises gas nozzles 7', 7 ″ and a central inlet 10, 10 'for cooling gas 13, 13'. At a point not shown in the drawing, the annular spinning dies 1', 1 ″ are supplied with spinning material 11, 11' which is spun to produce a compact annular fiber bundle 5', 5 ″ to which cooling gas is blown not only on the inside, but also on the outside. The blowing direction is indicated in the two figures by

arrows

22, 22 'and 6', 6", respectively.

The embodiments of the device according to the invention shown in the two figures differ in the central inlet points 10, 10 'for the cooling gas 13, 13'. The entry point 10 is designed as a simple tube with a baffle 12 and a passage 14. The inlet point 10 can be supplied with cooling gas 13, for example by means of a fan not shown in the figures. The air stream 13 hits the baffle 12, turns horizontally, flows out of the passage 14 as an air stream 22, and hits the annular fiber bundle 5' at the inner side of the annular fiber bundle. A flow or displacement body 15 for homogenizing the gas flow can be provided in the supply point 10. By blowing air not only from the outside but also radially from the inside to the fiber bundle 5', the cooling effect is significantly increased.

The central inlet point 10 'shown in fig. 3 has a plurality of individual chambers a-d to which cooling gas 13' is supplied. Due to the segmented structure of the entry point 10', different cooling media or cooling conditions can be used when blowing air into the fiber bundle. By means of the arrangement shown in fig. 3, the fiber bundle can also be exposed to the cooling gas over a longer distance and the textile value of the cellulose fibers can therefore be influenced more favorably.

The gas nozzles 7', 7 "which annularly surround the annular fiber bundle 5 can either be attached directly to the spinnerets 1', 1" or can form a separately constructed unit which is attached again to the spinnerets 1', 1 ". As regards the structural design, the structural design implemented in fig. 1 is suitable for this. The same applies to the entry points 10, 10'.

It is also possible to integrate air nozzles for blowing air into the fibers into the spinneret, wherein, of course, thermal insulation is of particular concern. Fig. 4 shows precisely one such embodiment, wherein fig. 4a shows a cross section of an apparatus according to the invention with a cylindrical spinneret housing (which can be heated, but the heating device is not shown), while fig. 4b shows a bottom view of the cross section of the embodiment.

Fig. 4a shows a schematic view of a spinneret 1'", wherein a spinning orifice 16'" is provided at the head of the cylindrical channel 17. The entry point of the spinning material 18 into the spinneret 1 "'is shown as 2'. During the spinning process, the spinning material in the channel 17 is compressed and extruded through the spinning orifice 16' ″. The spinneret plate 1 "'is covered on its capillary side by a circular plate 19 which contains circular cutouts 21 which are shaped and positioned on the plate 19 such that the extruded fibers 5"' emerge unhindered and can be drawn off. This cover of the spinneret 1 "' creates a cavity 20 into which cooling gas is directed (not shown). The plate 19 is designed and applied to the spinning plate 1' "in such a way that it does not contact the head of the channel 17, but forms an annular gap 7'", through which the cooling gas can exit and flow horizontally onto the extruded fiber bundle 5' "(shown in fig. 4a by the arrow 6'" in the gap 7' "). The annular gap 7 "'thus fulfills the function of the gas nozzle 7, 7', 7", which in the embodiments according to fig. 1, 2 and 3 is used in the form of a circle, respectively.

With this particular configuration, therefore, a ring of cooling gas is formed around each fiber bundle 5'", which makes it possible to effectively cool the compact fiber bundle 5'".

Fig. 4b provides a bottom view of the spinneret 1 "', showing the cross section of the plate 19, the cut-outs 21, from which the cooling gas flows out, and the spinning orifices 16"'.

In all embodiments as shown in fig. 2, 3 and 4a, a gas flow control unit is installed in front of the feeding device in the flow direction, which is controlled by a gas flow control system. The gas flow control unit and the gas flow control system are not shown in the drawings. However, once the expert has an understanding of the present invention, the expert can very easily determine their location. The gas flow control unit can be any type of control unit (e.g., a valve, flap, or other device capable of controlling flow within a tube). The gas flow control system can include a computer that can control the methods and apparatus to transmit control signals to the gas flow control unit electronically, pneumatically, hydraulically, or by another suitable principle. The gas flow control system must be programmed in a suitable manner in order to balance the different gas flows in the feed device in such a way that the original direction of the freshly extruded fibers along them towards the coagulation bath (8) is maintained.

The space 20 is covered with an insulating structure 23 on the spinneret side to prevent heat transfer from the spun material 18 to the cooling gas in the space 20.

Claims

1. An apparatus for producing a cellulose thread from a solution of cellulose in a tertiary amine-oxide, the apparatus comprising a spinneret with a spinning orifice and wherein,

a. a feed device for a cooling gas is arranged immediately below the spinning orifice for cooling the cellulose thread,

b. the spinning orifices of the spinneret are arranged in a ring,

c. the feed device for the cooling gas is arranged in the center of the ring formed by the arrangement of the spinning orifices,

d. providing a further feed device for cooling gas, the further feed device being provided outside the loop formed by the arrangement of spinning orifices,

the device is characterized in that a gas flow control unit is arranged in front of the feeding device along the flow direction, and the gas flow control unit is controlled by a gas flow control system.

2. The apparatus according to claim 1, characterized in that a flow or displacement body is provided in the feed device to smooth the flow of the cooling gas, the feed device being located in the center of the loop formed by the arrangement of the spinning orifices.

3. The apparatus of claim 1, wherein the spinneret orifices are grouped together.