HRP950610A2 - Spinning machine - Google Patents

Description

The present invention relates to a spinning device for carrying out the aminooxide-process in accordance with the dry/wet spinning process with a nozzle, which has openings for squeezing out the fiber, a tank with liquid for the spinning bath, with an element for tying the extruded fibers (into a bundle) and an air by the gap, which is determined as the distance of the nozzle to the surface of the liquid in the spinning bath.

The technique of the dry/wet spinning process generally consists in the fact that the spinning mass is extruded (extruded) through a mold, e.g. a spinning nozzle, into a medium in which the spinning mass does not settle, e.g. air or an inert gas, whereby, in the case of using a spinning nozzle, fibers are created that are stretched in that medium, and are finally led to the spinning bath (deposition bath), where the fibers coagulate.

The amine oxide process generally refers to the production of cellulose molds with the use of tertiary amine oxides. In this process, the cellulose is dissolved in a mixture of tertiary amine oxide and water, the solution is shaped using a molding tool and passed through a water bath for deposition, in which the cellulose is separated. N-methylmorpholine-N-oxide (NMMO) is primarily used as an amine oxide. Other amine oxides are described, for example, in EP-A-0 553 070. The process for the production of formable cellulose solutions is known, for example, from EP-A-0 356 419.

Carrying out the amine oxide process after the dry/wet spinning process is known, for example, from DE-A-29 13 589.

From WO 93/19230 and WO 95/04173, a recommended way of carrying out the amine oxide process and a device for the production of cellulose fibers is known, according to which a cellulose solution is formed in a tertiary amine oxide in a warm state and then the formed solution is introduced into the settling bath, to settle the resulting cellulose, the warm, formed solution being cooled before being placed in the settling bath. Cooling is accessed immediately after molding and consists of horizontal blowing of air onto the cellulose mold. The process according to this invention enables the spinning of a cellulose solution with a high fiber density, without the fibers joining (sticking) after exiting the nozzle.

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. Also according to this procedure, the cellulose solution is spun in the air gap, which is the gap between the nozzle and the surface of the spinning bath, stretched and led into the water bath for deposition. In DD-A-218 121 it is stated that the air gap can be reduced without unpleasant consequences, if a polyalkyl ether is added to the cellulose solution before spinning. A small air gap is therefore recommended, as it reduces the risk of freshly extruded fibers sticking together.

EP-A-0 574 870 describes a dry/wet spinning process for the processing of cellulose solutions in tertiary amine oxides and points to the advantage of a small air gap. By means of this process, according to the information provided in the patent announcement, it is possible to spin with a small air gap and with a large number of spinning holes per unit area. Regardless of the above, the fibers must not stick together during spinning. It is recommended to contact the spun fibers with the spinning bath in a funnel. The spinning bath is also led through this funnel with uniform flow with the fibers. The axis of the spinning hopper is generally perpendicular to the plane of the nozzle, and the flow of the spinning bath is directed from top to bottom, the flow occurring due to the free fall of the spinning bath.

Tightening or drawing of freshly extruded fibers is achieved according to EP-A-0 574 870 so that the fibers flowing from the spinning bath are generally accelerated to their drawing speed. This already known spinning device has the disadvantage that the tube of the spinning funnel, due to its relatively small diameter, sets an upper limit for the bundle of fibers with regard to the total cross-section, which is still too low for carrying out the process in large industrial plants. Thus, according to experience, with a diameter of 6 mm, as stated in EP-A-0 574 870, it is possible to guide only a bundle of fibers consisting of a maximum of 100 fibers through the funnel, since the liquid of the spinning bath must also be transported through the funnel . This means that when using a spinning funnel of this type, only a nozzle with a maximum of 100 spinning holes can be used.

If, on the other hand, a wide nozzle with about a thousand spinning holes is used, as for example described in Austrian Patent AT-B 397,392, then the funnel tube must be correspondingly larger, as a result of which more liquid flows into the spinning bath, and care must be taken to circulation. This high spinning bath liquid flow leads to turbulent flows in the spinning bath, which adversely affects the dry/wet spinning process.

GB-A-1,017,855 describes an apparatus for dry/wet spinning of synthetic polymers. The use of a spinning funnel is also recommended here, through which the liquid of the spinning bath would flow in the same direction as the extruded fibers. The nozzle is located about 0.5 cm above the surface of the spinning bath. The task of this invention is to provide a spinning device, which would enable simple implementation of the amine oxide process according to the dry-/wet spinning process and which would ensure high-quality spinning (high spinning safety), whereby high-quality spinning is considered to be the highest possible final pull-out rate (=lowest possible titer) before the fiber breaks. The next measure for spinning ability is the duration, in which it can be spun, without spinning errors, which require technical assistance. Furthermore, even when using a spinning nozzle with a large number of openings, the sticking of freshly extruded fibers in the air gap should be avoided and, if possible, a constant titer should be achieved (small titer deviations).

The spinning device according to the present invention for carrying out the amine oxide process according to the dry-/wet spinning process with

one spinning nozzle, which has spinning openings for extruding the fibers, one blowing device, by means of which the extruded fibers are cooled, immediately after they leave the spinning openings, a tank for the liquid of the spinning bath, one element for tying the bundle, which is provided in the liquid spinning bath for tying the extruded fibers into a bundle, and the air gap, which is determined as the distance of the spinning nozzle to the surface of the liquid of the spinning bath, is indicated by,

- that the element for tying into a bundle is located at such a distance from the spinning nozzle, that the angle (α) formed by the fibers to the vertical on the liquid surface of the spinning bath is a maximum of 45°,

- and that the condition is met

[image]

where do is the distance (mm) between one spinning hole and its neighboring spinning hole on the nozzle, h is the distance (mm) of the element for tying into bundles to the nozzle, 1 is the air gap (mm), where

[image]

It has been shown that the task of this invention can be solved in this way, if the spinning device is constructed in such a way that the above two conditions are met (angle a maximum of 45° as well as the fulfillment of the aforementioned inequalities). When using spinning nozzles with a high opening density, it is necessary to cool the freshly extruded fibers immediately after exiting the spinning openings. This cooling has long been known to any person skilled in the art (see e.g. WO 95/04173).

A recommended embodiment of the spinning device according to the present invention is indicated by the fact that the element for tying into bundles is designed as a turning element, on which the fibers are not only tied into bundles but are also turned.

It turned out to be good that the turning element is constructed in such a way that the element itself does not turn when the fibers are turned. According to this design, no reel or roller is provided as a turning element. This ensures that the cracked fibers do not wind up on the turning element. This makes it easier to carry out the amine oxide procedure.

The following recommended embodiment of the spinning device according to this invention is indicated by the fact that the angle a does not exceed 20°. In practice, it has been shown that for the safety of spinning in the dry-/wet spinning process, it is better that the extraction angle α in the air gap be as small as possible, and preferably not exceed 20°. This can reduce the risk of fibers sticking together in the space between the nozzle and the surface of the spinning bath and increase the safety of spinning.

This invention also relates to a spinning device for carrying out the amine oxide process after the dry-/wet spinning process with:

- a spinning nozzle, which has openings for extruding fibers,

- a blowing device, by means of which the extruded fibers are cooled, after passing through the spinning holes,

- a container containing liquid for the spinning bath,

- a diverting element, which in the liquid for the spinning bath is intended for tying into bundles and diverting the extruded fibers, and

- by the air gap, which is determined as the gap between the nozzle and the liquid of the spinning bath,

which is characterized by the fact that the turning element is designed so that it does not turn when the fibers are turned.

The next expedient embodiment of the spinning device according to this invention is that the spinning nozzle has:

- the rotationally symmetrical body of the nozzle, which has a supply for cooling gas in the middle,

-feed for cellulose solution,

-ring insert for spinning with openings for spinning, i

- a deflector plate for deflecting the flow of cooling gas onto the fibers, which are extruded from the spinning opening, so that the flow of cooling gas comes in principle perpendicular to the fibers.

In this way, it is possible to spin with even more openings for spinning and at the same time prevent newly extruded fibers from sticking together in the air gap. Cooling of ring fibers by blowing in cooling air is known from WO 95/04173.

The next recommended embodiment of the spinning device according to the present invention consists in the fact that the container containing the liquid for the spinning bath is connected to a lifting device, by means of which the container can be vertically moved closer and further away from the nozzle, thereby changing distance 1, and that the element for tying into bundles is placed in such a way that the distance h remains constant despite these shifts.

With the help of drawings consisting of figures 1, 2 and 3, the embodiment of the invention is explained in more detail. The drawing shows a representation of the dry-/wet-spinning process together with the corresponding relationship of important sizes.

On Fig. 1, the container for receiving the liquid for the industrial bath is marked with the number 1, and the surface of the liquid for the industrial bath is marked with la. During the spinning process, the spinning mass is extruded through the nozzle 3, and the extruded fibers 4, 5 are drawn through the air gap 1 into the liquid for the spinning bath, where they coagulate. On the turning element 2, which is a cylindrical rod, which cannot be turned, the coagulated fibers are joined, turned and pulled diagonally upwards. The air gap 1 is defined as the distance between the lower side of the nozzle 3 and the surface la of the spinning bath liquid. The angle defined above, which the fibers make to the vertical on the liquid surface of the spinning bath, is denoted by α.

The reference number 4 indicates the fiber, which originates from the opening for spinning, which is located on the outer edge of the circular ring, derived from the opening for spinning in the nozzle 3. d1 is the radius (mm) of the circle formed by the spinning openings, which is limited towards the outer side. The distance between that opening for spinning and the adjacent opening for spinning 5 is marked with do, which means the distance between certain centers of two adjacent openings. h is the distance of the deflection element 2 to the nozzle 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), by means of which the container 1 is moved vertically and thus the size of the air gap 1 can easily be changed.

It turned out to be good, that the turning element 2 is not attached to the tank 1, but to foresee the possibility of moving the tank 1, while the distance h remains constant. In such a simple way, while keeping the distance h constant, the air gap 1 can be changed. This means a significant simplification in the adjustment of the spinning device according to this invention. Figures 1 and 2 show such embodiments of the spinning device according to the present invention.

Fig. 2 basically shows the spinning device of Fig. 1, where the same parts are marked with the same signs. The non-rotating turning element 2 is connected via a rigid lever 6 to the fixed element 7, which is not connected to the tank 1, so that when the tank 1 is raised or lowered, the element 7 does not move together with it. Element 7 can be, for example, one wall. On Fig. 2 shows two positions of tank 1, where the lower position is indicated by a dashed line. The device for raising and lowering container 1 is not shown. From Fig. 2, it is visible that with the raising and lowering of the container 1, the air gap decreases or increases, while at the same time the gap h remains the same.

Figure 3 shows the following embodiment of the spinning device according to the present invention. According to this design, the turning element 2 is anchored in the bottom 8 by means of a rigid lever 9. The lever 9 protrudes through the corresponding opening 11, which is provided on the container 1. In order to prevent the liquid from leaving the container 1, a casing 10 is provided for sealing, which by pressing deforms, when container 1 is lowered using a device not shown.

Using the following examples 1, 2, 3 and 4, the invention is explained in more detail, whereby examples 1 and 2 show the influence of the angle α on the possibility of spinning cellulose solutions. Example 4 documents the positive effect of a non-rotatable deflection element on spinning capability.

Example 1

A spinning device is used, which in principle corresponds to Fig. 1, whereby the spinning funnel according to EP-A-0 574 870 is used as the element for tying the bundles. The spinning nozzle described in WO 95/04173 and published here is used as the spinning nozzle.

This already known nozzle (number of openings: 3960; diameter of openings: 100 um; outer diameter of the nozzle (outer series of openings) d1 145 mm) has a rotationally symmetrical nozzle body, which in the middle has an inlet for cooling gas, an inlet for cellulose solution (13 ,5% cellulose; temp.: 120°C), ring-shaped, deeply placed spinning cartridge made of precious metal with spinning openings, whose cross-section spinning cartridge is made in the form of a bath, a baffle plate for diverting the flow of cooling gas onto the cellulose fibers, which are extruded from spinning holes (extrusion: 0.025 g/min), so that the flow of cooling gas (24 m3/h) in principle comes perpendicular to the extruded cellulose fibers. The spinning holes in the insert are spaced from each other (hole-hole spacing up to: 1000 um). Air gap 1 has a length of 15 mm. The air in the air gap has a temperature of 24.5°C and a water content of 4.5 g water/kg air.

Several experiments were performed for spinning, in which, with the same air gap 1, the distance h of the point of attachment in the funnel bundles (the transition from the cylindrical tube to the actual funnel) to the surface of the nozzle varies so that the condition is met

[image]

(with 1=15 and up to=1000).

In each experiment, the maximum final pull-out is measured, that is the maximum attainable final speed of fiber extraction at the point of fiber breakage. The results are shown in table 1:

TABLE 1

[image]

It can be seen from Table 1 that up to an angle of approx. 40° cannot see a reduction in output speed, and thus no deterioration in spinning ability. From an angle of 45°, however, the maximum final exit speed is significantly reduced. At an angle of about 61°, the solution can no longer be spun.

Example 2

A spinning device is used, which corresponds to FIG. 2, and the one that is schematically described in WO 95/04173 is used as a nozzle [number of openings: 28,392; hole diameter: 100 µm; outer diameter of the nozzle (outer series of openings) d1: 155 mm; aperture-aperture spacing up to: 500 um].

The cellulose solution used contained 13.5% cellulose and had a temperature of 120°C. The extrusion rate was 0.025 g/min.

Air gap 1 has a length of 20 mm. The air in the air gap had a temperature of 12°C and a water content of 5g of water per kg of air. The fibers are deflected on a non-rotating cylindrical rod 2 and drawn diagonally upwards from the spinning bath.

At the same air gap 1, the distance h varies again and, analogously to example 1, determines the maximum speed of the final exposure as well as the angle a. The results are listed in table 2.

TABLE 2

[image]

As can be seen from Table 2, when the angle a changes from 13° to 34°, there is no decrease in the maximum velocity of the final exposure. If the angle a increases to 46°, then the speed of the final exit is drastically reduced, this means the possibility of spinning. With the subsequent reduction of the distance h (and thus the increase of the angle a), the solution can no longer be spun.

Example 3

The same spinning device described in Example 2 is used, and the air gap 1 is constantly adjusted to 30 mm. The spacing h varies again. The safety of solution spinning under the aforementioned conditions was characterized by the occurrence of errors in spinning (fiber breaks, ultimate sticking of fibers to each other).

High spinning reliability is achieved when practically no spinning errors occur in a period of more than 15 minutes. If several errors appear within a period of 15 minutes or earlier, spinning is possible from a technical point of view only with constant technical supervision.

Furthermore, the safety of spinning is characterized by specifying the time (period), where in the following Table 3, the data ">15 min" means that a good spinning effect was achieved (practically without spinning errors within 15 minutes). An indication of, for example, "< 10 min" means that before the expiration of 10 minutes after the start of spinning, huge spinning errors occur, which require an interruption of the spinning process.

TABLE 3

[image]

It is evident from Table 3 that up to a distance h of 115 mm, a good quality of spinning is achieved. If an even smaller h is chosen, the conditions set according to the invention are no longer met, and the possibility of spinning deteriorates drastically. This is the case with the last two experiments. This deterioration in spinning appears in the proposed example at an angle a well below 45°.

Example 4

In the pilot device for the production of cellulose fibers according to the amine oxide process, the method and type of fiber deflection in the spinning bath was investigated through numerous individual experiments with the spinning device according to this invention. Rotationally symmetrical turning elements that can be turned in various designs (reels with glass rods, which have a smooth or wrinkled surface) were tested. In those experiments, the following was always established again: as soon as the turning element turns around its axis, the fibers are wound on the turning roller in a short period of time. The cause of winding is that in the spinning bath, individual fibers sometimes break, which are then caught on the turning roller, then the turning roller leads them further and by guiding the other fibers, causes more and more windings. In doing so, the spun fibers are damaged, because the fibers wound on the turning roller must be removed mechanically, which leads to a lower quality of the final product.

It has been shown in practice that when using a turning roller that can be turned in a period of less than 30 minutes, the spinning process must be interrupted in order to remove the fibers wound on the turning roller.

If, while observing other parameters, the turning of the turning element is omitted; there is practically no more coiling. It has been shown that in this way the continuous spinning process can be carried out for several hours. The use of turning elements that can be turned should be avoided. In order to ensure trouble-free operation, it is necessary to design all turning elements as non-rotating elements if possible.

Claims (7)

1. Spinning device for carrying out the amine oxide process after the dry-/wet spinning process with - a nozzle, which has openings for spinning to squeeze out (extrude) fibers, - a blowing device, with which the extruded fibers can be cooled, immediately after exiting the spinning holes, - a container with liquid for the industrial bath, -the element for tying into bundles, which is provided in the liquid for the spinning bath for tying the extruded fibers, and - by the air gap, which is defined as the gap between the nozzle and the liquid surface of the spinning bath, i - by the air gap, which is defined as the gap between the nozzle and the liquid surface of the spinning bath, indicated by that the element for tying into bundles (2) is located at such a distance from the nozzle (3), that the angle (α) formed by the fibers to the vertical on the surface (la) of the liquid of the spinning bath is a maximum of 45°, and that the request is fulfilled [image] where do is the distance (mm) between one spinning hole and its neighboring spinning hole on the nozzle (3), h is the distance (mm) of the element for tying into bundles (2) to the nozzle (3), and 1 is the air gap (mm ), whereby [image] 2. The spinning device according to patent claim 1, characterized in that the element for tying into bundles (2) is designed as a turning element (2), on which the fibers (4; 5) are not only tied into bundles but also turned. 3. Spinning device according to patent claim 2, characterized in that the turning element (2) is designed so that it does not rotate when the fibers (4; 5) are turned. 4. Spinning device according to one of claims 1 to 3, characterized in that the angle (α) is a maximum of 20°. 5. Spinning device for carrying out the amine oxide process according to the dry-/wet spinning process with - nozzle, which has openings for pushing out fibers, - a blowing device, with which the extruded fibers can be cooled, immediately after exiting the spinning holes, - a container with liquid for the industrial bath, - a diverting element, which is provided in the liquid for the spinning bath for connecting into bundles and diverting the extruded fibers, and - the air gap, which is defined as the gap between the nozzle and the liquid for the spinning bath, characterized by the fact that the turning element (2) is constructed in such a way that it does not turn when the fibers (4;5) are turned. 6. Spinning device according to one of claims 1 to 5, characterized in that the nozzle has: -one, in principle, rotationally symmetrical body of the nozzle, which has a supply for cooling gas in the middle, -feed for cellulose solution, -ring insert for spinning with openings for spinning, i - a deflector plate for deflecting the flow of cooling gas onto the fibers, which are pushed out of the spinning holes, so that the flow of cooling gas in principle comes perpendicular to the fibers. 7. Spinning device according to one of patent claims 1 to 6, characterized in that the container containing the liquid for the spinning bath is connected to a lifting device (elevator), by means of which the container can be moved in the vertical direction to or from the nozzle, which changes the distance 1, and that the element for tying into bundles is placed in such a way that the distance h remains constant despite this movement.