CN218059316U - Apparatus for the manufacture of cellulose threads from solutions of cellulose in tertiary amine oxides - Google Patents

Abstract

The utility model relates to a device for manufacturing cellulose moldings, which is used for manufacturing cellulose threads from a solution of cellulose in tertiary amine oxides, the device includes a spinneret with spinning holes, and wherein a. a feed for cooling gas is provided immediately below the spinning holes for cooling the cellulose strands, b. the spinning holes of the spinneret are arranged in a ring, c a feed for the cooling gas is provided in the center of the ring formed by the arrangement of the spinning holes, d. an additional feed for the cooling gas is provided, the additional feed The device is arranged outside the ring formed by the arrangement of the spinning holes, and a gas flow control unit is installed in front of the feeding device in the flow direction, the gas flow control unit being controlled by a gas flow control system.

Description

Apparatus for the manufacture of cellulose threads from solutions of cellulose in tertiary amine oxides

technical field

The utility model relates to a device for implementing a method for preparing a cellulose molded body, wherein a solution of cellulose in a tertiary amine oxide is molded in a hot state, and the molded solution is introduced into a coagulation bath, In order to solidify the contained cellulose.

Background technique

It is known from US Pat. No. 2,179,181 that tertiary amine oxides are capable of dissolving cellulose and that cellulose shaped bodies can be obtained from this solution by coagulation. A method for preparing such solutions is known, for example, from EP-A-0 356 419. According to this publication, a cellulosic suspension is first prepared in an aqueous tertiary amine oxide. Amine oxides contain 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 device which can be evacuated.

A method of the type described at the outset is known from DE-A 2 844 163 and DD-A 218 121 . To produce cellulose fibers or cellulose films, an air space or air gap is arranged between the spinneret and the coagulation bath in order to effect drawing at the die. This pulling is necessary because it becomes very difficult to pull the fibers after the shaped spinning solution comes into contact with the aqueous coagulation bath. The fiber structure produced in the air gap is fixed in a coagulation bath.

However, there is a danger in the air gap that the individual fibers which have not yet coagulated will stick together or will fuse together due to their extremely high viscosity, thus making it impossible to spin the fibers. Of course, the longer the gap (air space) between the die plate and the surface of the coagulation bath, the greater the risk of such sticking. On the other hand, a long gap can be advantageous because the orientation of the cellulose molecules takes a certain amount of 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 has an adverse effect on the economics of the spinning process.

While the use of short air gaps does allow spinning with high hole densities, it also compromises the reliability of the spinning process as liquid from the coagulation bath reaches the spinning boreholes due to capillary action of the filaments Or on the exit side of the spinning hole. As a result, the formed but still fluid fiber material cannot withstand the pull, ie, does not achieve the desired fiber thickness. At the same time, it can be shown that the textile values with regard to the strength and elongation of the fibers are hardly affected by the shortened residence time in the air gap.

In DD-A 218 121 it is specified that by adding a polyalkylene ether, especially polyethylene glycol, to the spinning solution, the length of the drawing gap on the die can be shortened, with a corresponding reduction in the sticking of the individual fibers together without any influence on spinning reliability or on fiber strength. The extreme stickiness of the spun fibers and the overcoming of this problem is also mentioned in DE-A 2 844 163, where it is proposed, among other things, to spray the fibers in the air gap with a cellulose-insoluble liquid.

Tests have shown that not all proposed solutions are satisfactory with regard to the achievable spun fiber densities or with regard to the influence on the textile properties of the cellulosic fibers. According to DE-A 2 844 163, the distance between the spinneret and the surface of the coagulation bath is 270 mm, but this apparently only allows a spinning fiber density of about 0.0046 fibers/mm ² (corresponding to 0.0046 fibers in the spinneret hole/mm ² spinning hole density). Large-scale spinning with such small hole densities is inconceivable. In order to do this, it is necessary to use a spinneret with a hole density greater than 0.1 holes/mm ² . Such a spinneret is described, for example, in Austrian patent application A2724/89.

Contents of the invention

Now, expressly express the utility model here, and the utility model concerns the problem that improves the method mentioned at the beginning by suitable equipment, makes this method allow to reduce the stickiness of the cellulose molded body that just extrudes, and need not give Add any kind of additives to the spinning material, and there is no need to spray the surface of the molded body with a coagulant. In particular, the invention solves the problem of providing a process for the production of cellulose fibers in which, by using a spinneret with a high hole density, it is possible to spin dense fiber bundles, in order to better control the The textile properties of the spun fibers direct the dense fiber bundles through large air gaps to the coagulation bath.

Despite this dense fiber bundle, there should be no adhesion between the individual fibers despite the large air gaps.

The apparatus according to the invention is characterized in that it enables the hot forming spinning solution to be cooled before it is brought into contact with the coagulation bath, whereby cooling takes place immediately after forming. The best way to cool the molding solution is to expose it to a stream of air.

The use of a gas flow substantially perpendicular to the spinning direction has proven especially valuable when using a spinneret for the production of cellulose fibers by shaping a cellulose solution. Surprisingly, it has been shown that the above-mentioned problem of sticking can be overcome in a simple manner by exposing the freshly spun fibers, for example, to an air stream. Even the simple blowing of the fiber bundles with a fan ensures that ^spinnerets with up to 0.7 holes/mm can be used and air gaps up to 70 mm long can be selected without any sticking of the individual fibers in the air gaps.

The device according to the invention is also suitable for the production of cellulose films, wherein the cellulose solution is led through a film forming device which is characterized in that the direction of film formation is substantially perpendicular to the air flow.

When using spinnerets with an even higher hole density, the air distribution provided by the fans 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 air streams, wherein said air streams are preferably applied to the forming solution on the opposite side.

One embodiment of this variant of the plant for producing cellulose fibers according to the invention comprises means for guiding the hot cellulose solution through a spinneret having a large number of spinning holes, said The spinning holes are arranged substantially annularly, wherein the hot forming solution emerging as the spun fibers is exposed to two air streams so that one air stream is directed radially outward and the other air stream is directed radially inward .

The cooling effect can be increased in this way, so that fiber bundles with a density of at most 1.4 fibers/mm ² can be guided over a gap of at least 50 mm without the individual fibers sticking together.

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

The utility model also relates to a device for preparing cellulose fibers from a solution of cellulose in a tertiary amine oxide, wherein the device comprises a spinneret with spinning holes. The device according to the invention is characterized in that an inlet for cooling gas is provided immediately downstream of the spinning hole for cooling the cellulose fibers.

A special embodiment of the device according to the invention comprises substantially annularly arranged spinning holes in the spinneret, the device has an inlet for the cooling gas, which is arranged in the hole formed by the spinning holes. the center of the ring.

In order to uniformly cool very dense fiber bundles extruded from spinnerets having a hole density of more ^than 0.7 holes/mm, it has proven to be advantageous to provide an additional cooling gas flow which Guided onto the fiber bundle from the outside. Thus, the configuration of the device according to the invention exhibits an additional 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 its inner side but also on its outer side. It has been shown that the cooling effect is significantly increased in this way.

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

Flow devices or baffles 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 device according to the invention comprises spinning holes arranged in groups in the spinneret.

Description of drawings

The device according to the present invention is further explained by means of the accompanying drawings, wherein,

Fig. 1 schematically shows a preferred embodiment of the equipment for preparing cellulose fibers according to the present invention;

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

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

Figure 4a shows another preferred embodiment of the device according to the present invention;

Figure 4b shows a bottom view of the spinneret.

detailed description

In FIG. 1 is shown a heatable spinneret 1 (heating means not shown), to which spinneret is supplied via a feed line 2 a spinning material 3, i.e. a hot cellulose solution at a temperature of approximately 100° C. . 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 holes 16 is cooled by means of an inert gas 6 , preferably air, which is directed through the gas nozzles 7 onto the fiber bundle 5 leaving the spinneret 1 . With this gas flow it is possible to use spinnerets with a high hole density without the spun fibers sticking together during the spinning process.

The fiber bundle 5 passes through the air gap, which is defined as the distance between the spinneret 1 and the surface of the coagulation bath 8, and then the fiber bundle enters the coagulation bath 8, is collected together by guide rollers 9 and is lead out. According to the invention, the blowing of the gas and the cooling of the fiber bundle respectively enable the use of a relatively long gas gap, allowing sufficient time for the orientation of the cellulose molecules during drawing of the fibers. The drawing-off is achieved by pulling the fiber bundle 5 by means of the rollers 9 at a greater speed than the fiber bundle leaves the spinneret 1 .

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

Further embodiments of the spinning device according to the invention shown in FIG. 1 , comprising spinnerets and cooling gas nozzles, are schematically shown in FIGS. 2 , 3 and 4 . With these embodiments, even denser fiber bundles can be processed, ie spinnerets with an even higher hole density can be used.

2 and 3 show a cross-section of an annular, heatable (heating means not shown) spinneret 1 ′, 1 ″ and a device for blowing gas comprising gas nozzles 7 ′, 7" and a central inlet 10, 10' for cooling gas 13, 13'. At points not shown in the figures, the annular spinneret 1', 1" is supplied with spinning material 11, 11' which is spun to produce a dense annular fiber bundle 5', 5 ”, the cooling gas is blown against the fiber bundle not only on the inside but also on the outside. The blowing directions are indicated in the two figures by arrows 22, 22' and 6', 6", respectively.

The embodiment of the device according to the invention shown in the two figures differs in the central entry point 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 eg by means of a fan not shown in the figures. Air flow 13 hits baffle 12, turns horizontally, exits channel 14 as air flow 22, and hits looped fiber bundle 5' inside the looped fiber bundle. A flow or displacement body 15 for homogenizing the gas flow can be provided in the supply point 10 . By blowing air radially to the fiber bundle 5' not only from the outside, but also from the inside, the cooling effect is significantly increased.

The central entry point 10' shown in Figure 3 has a plurality of individual chambers a-d to which cooling gas 13' is supplied. Due to this segmented structure of the entry point 10', different cooling media or cooling conditions can be used when blowing air to the fiber bundle. The arrangement shown in FIG. 3 also makes it possible to expose the fiber bundles to the cooling gas over a longer distance and thus to influence the textile value of the cellulose fibers more favorably.

The gas nozzles 7 ′, 7 ″ annularly surrounding the annular fiber bundle 5 can either be attached directly to the spinneret 1 ′, 1 ″, or can form a separately constructed unit which is again attached to the spinneret 1', 1". With regard to the structural design, the structural design implemented in FIG. 1 applies here. The same applies to the entry points 10, 10'.

It is also possible to integrate air nozzles for blowing air on the fibers into the spinneret, wherein, of course, particular consideration must be given to thermal insulation. Just such an embodiment is shown in FIG. 4 , wherein FIG. 4 a shows a cross-section of a device according to the invention with a cylindrical spinneret housing (the spinneret housing can be heated , but the heating means are not shown), while Fig. 4b shows a bottom view in section of this embodiment.

Figure 4a shows a schematic view of a spinneret 1'", wherein a spinning hole 16'" is provided at the head of a 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 channels 17 is compressed and extruded through the spinning holes 16'". The spinneret 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 in such a way that the extruded fibers 5 ″ do not Come out hindered and be able to be drawn out. This covering of the spinneret 1 ″ produces a cavity 20 into which cooling gas is guided (not shown). The plate 19 is designed and applied to the spinneret 1 ″ in such a way that it does not touch The head of the channel 17, but forms an annular gap 7'", through which the cooling gas can come out and flow horizontally onto the extruded fiber bundle 5'" (in Figure 4a by the arrow 6'" in the gap 7'"). The annular gap 7'" thus fulfills the function of the gas nozzles 7, 7', 7", which are used in the form of circles in the embodiments according to Fig. 1 , Fig. 2 and Fig. 3, respectively.

Thus, by means of this particular structure, around each fiber bundle 5'" a ring of cooling gas is formed, which makes it possible to effectively cool the dense fiber bundle 5'".

Figure 4b provides a bottom view of the spinneret 1'" showing the section of the plate 19, the cutouts 21 and the spinning holes 16'" from which the cooling gas flows.

In all the embodiments shown in Fig. 2, Fig. 3 and Fig. 4a, a gas flow control unit is installed in front of the feeding device along the flow direction, which is controlled by the 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 understands the invention, the expert can determine their location very easily. The gas flow control unit can be any type of control unit (such as a valve, flap or other device capable of controlling the flow in the pipe). The gas flow control system can include a computer capable of controlling methods and apparatus to transmit control signals electronically, pneumatically, hydraulically or by other suitable principles to the gas flow control unit. The gas flow control system has to be programmed in a suitable way to balance the different gas flows in the feed in such a way that the freshly extruded fibers are kept in their original direction towards the coagulation bath (8).

The space 20 is surrounded on the spinneret side by an insulating structure 23 in order to prevent the transfer of heat from the spinning material 18 to the cooling gas in the space 20 .

Claims (3)

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.

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