EP0871805A1

EP0871805A1 - Process and device for the formation of monofilaments produced by melt-spinning

Info

Publication number: EP0871805A1
Application number: EP96944640A
Authority: EP
Inventors: Jürgen Büdenbender; Eckhard Gärtner
Original assignee: Bayer Faser GmbH
Current assignee: Asahi Kasei Spandex Europe GmbH
Priority date: 1996-01-03
Filing date: 1996-12-23
Publication date: 1998-10-21
Also published as: US6036895A; DE19600090A1; WO1997025458A1; JP2000503076A

Abstract

The invention relates to a continuous process and a device for the formation of monofilaments, produced by melt-spinning and having a diameter of 60 νm to 2500 νm, from fibre-forming polymers. During said process the molten polymer from a spinning head (17) is spun in the air, is blown laterally in a spinning column (2) at a defined air speed, and is subsequently cooled in a liquid bath (5).

Description

Method and device for producing melt-spun monofilaments

The invention relates to a continuous process and an apparatus for

Production of melt-spun monofilaments with a diameter of 60 μm to 2500 μm from thread-forming polymers, in particular polyamide. In this process, the polymer melt is spun from a spinning head in air, blown to the side in a spinning shaft with a defined air velocity profile and then cooled in a liquid bath

The processes for the production of monofilaments from thermoplastic polymers without additional air blowing between the spinning head and the spinning trough with a cooling liquid are fundamentally known. In the handbook of plastic extrusion technology II, Carl Hauser Verlag Munich, Vienna, 1986, pages 295 to 319, the known process steps are described in detail. Thereafter, thermoplastic monofilaments (with a diameter greater than 60 μm) can be spun, for example in water, with an outlet speed of the finished monofilaments of a maximum of 600 m / min

Monofilaments with a much smaller cross-section and multifilament threads are spun directly in air as a coolant at a significantly higher outlet speed using other processes. For example, German published patent application DE 41 29 521 AI describes a device for the rapid spinning of multifilament threads at a winding speed of at least 2000 m / min

In the latter process, monofilaments or multifilament threads are spun in air and wound up directly. A special feature of this process is the cow device used. It consists of a porous tube which is open in the spinning direction and which is arranged concentrically with the thread sheet. At the high winding speed, an active supply of a cooling medium is dispensed with. The process described there relates to filament yarns with a single titer of filaments from 0.1 to 6 dtex and is not applicable to monofilaments with a diameter greater than 50 μm (approx. 22 dtex)

International patent application WO 91/1 1547 describes a method and a device for the rapid spinning of monofilaments with a single titer of 1 up to 30 dtex (corresponding to approx. 10 to 57 μm) are known. Here, the melt-spun monofilaments are cooled with blown air, drawn off via a friction element, provided with a preparation and wound up at a speed of up to 6000 m / min. This process differs fundamentally from the process according to DE 41 29 521 AI relating to the active cooling of the

Monofilament through blowing air and through the use of the friction element, through which the thread tension is influenced

In principle, both direct spinning drawing processes (according to DE 41 29 520 AI and WO 91/1 1547) are limited to the production of thin monofilament diameters (ie with a thread diameter <57 μm) due to the unfavorable heat dissipation due to air cooling and the poor internal heat conduction in the thread

The German patent application with the file number P 43 36 097 1 describes a continuous high-speed production process for the production of melt-spun monofilament threads with a diameter of 60 μm to 500 μm. In this method, the polymer threads formed are laterally underneath the spinning head over a distance of 1 to 10 cm blown with tempered air from blowing nozzles to stabilize the smooth running of the threads. After the air cooling, the polymer threads are cooled in a liquid bath

The surface of the melt thread running only through a short air gap, for example according to the last-mentioned method and then spun directly into a liquid, shows a structure similar to that of an orange peel. The monofilaments show a loss of strength and a large spread with regard to their knot strength

In addition, the sudden cooling of the monofilaments in the cooling liquid leads to a pronounced core-sheath structure of the threads, which also negatively influences the mechanical properties of the threads

Due to the unfavorable heat dissipation in air cooling and the poor internal heat conduction in such processes in which spinning is only carried out in air as a cooling medium, monofilament production is limited to a diameter of <57 μm

REPLACEMENT BLAπ (RULE 26) An additional air blowing between the spinning head and the spinning bath by means of blowing nozzles over an air distance of 1 to 10 cm (according to DE 43 36 097) leads to satisfactory textile properties with rapidly spun thin monofilaments (with a diameter of <200 μm). The use of the air cooling section described is not sufficient for thicker monofilaments. In addition, the method is extremely susceptible to air movement in the area of the thread formation, as a result of which the running safety of the system is impaired.

The invention has for its object to improve the spinning process for monofilaments described so that the spinning security and the textile properties of the monofilaments obtained, in particular their knot strength, are increased.

The object is achieved according to the invention by a continuous process for the production of monofilament threads with a diameter of 60 μm to 2000 μm from thread-forming thermoplastic polymers by melt spinning the melted polymer from a spinning head in air, blowing on the side with cooling gas in a spinning shaft, cooling the threads formed in one

Liquid bath, removal of the adhering liquid, optionally preparation, stretching of the threads in one or more stages, fixing and winding up the threads at an outlet speed of the fixed threads of 100 to 4000 m / min, characterized in that the cooling gas has a temperature of 0 to 50 ° C and that the cooling gas falling over the direction of the thread

Speed profile, measured perpendicular to the direction of the threads, shows that the coolant has a temperature of -10 to 150 ° C.

The thread-forming polymer is melt-spun in particular from a basically known melt spinning head in air, in a spinning shaft with a defined air velocity profile with tempered air (a temperature of

0 ° C to 50 ° C) preferably from one side from blowing nozzles or, in the case of round spinning nozzles, annularly blown from the side from ring nozzles and then cooled in a liquid bath at a temperature of 5 ° C. to 50 ° C.

In a preferred variant, the air speed across the monofilaments is just below the spinneret (for example at a distance of 0.5 to 6 cm from the nozzle) from 0.1 to 10 m / sec, in particular from 0.1 to 2 m / sec sec, and falls to a lower but above all in the further course of the spinning shaft seen the longitudinal section surface of the spinning shaft extremely uniform Luftge¬ speed of 0.001 m / sec to 1 m / sec, in particular 0.01 to 0.2 m / sec

In a preferred method, the cooling gas flows from nozzles, which are arranged in a ring around the filaments in the spinning shaft, into the spinning shaft, and the cooling gas is sucked out together with the outgassings from the spun thread beneath the blowing nozzle

In a further variant of the method, the nozzles are arranged on one side in the spinning shaft and the cooling gas, together with the outgassing, is drawn off from the spun threads relative to the blow nozzles

Also preferred is a method using a spinning shaft which covers the distance between the spinning head and the liquid bath. The spinning shaft can have a length of 2 to 200 cm. The spinning shaft preferably has a length of 8 to 60 cm

In a preferred variant of the method, the air speed in the spinning shaft is transverse to the monofilaments at a distance of 0.5 to 6 cm from the

Spinning nozzle 0.05 to 10 m / sec, in particular 0.1 to 2 m / sec. The air speed in the spinning shaft, in particular at a distance of 6 to 200 cm from the spinning nozzle, is from 0.001 m / sec to 1 m / sec, preferably of 0.01 to 0.2 m / sec

The monofilaments are preferably blown in the spinning shaft with tempered air at a temperature of 0 to 50 ° C., in particular 10 to 30 ° C.

In a further preferred variant of the method, the air blown into the spinning shaft, together with the outgassings from the spun threads, is sucked off uniformly over the entire spinning shaft relative to the air inlet. In particular, if the spinning gas is suctioned off in the spinning shaft, a pressure difference to the ambient pressure becomes high from 10 to

100 Pa generated

The temperature of the cooling bath is preferably 5 to 50 ° C The outlet speed of the threads is preferably 1000 to 3500 m / min. The monofilaments obtainable from the process have in particular a diameter of 100 to 400 μm, preferably 180 to 250 μm.

Polyamide, polyethylene terephthalate, polybutylene terephthalate, polypropylene and polyethylene are particularly suitable as thread-forming polymer. The preferred polymer is polyamide, in particular polyamide-6, polyamide-6.6, polyamide-6.10, polyamide-6.12, polyamide 11, polyamide 12, a mixture of the polyamides mentioned or a copolyamide of the polyamides mentioned. A copolyamide consisting of polyamide-6 and polyamide-6.6, a copolyamide made of polyamide-6 and polyamide-12 and a copolyamide consisting of polyamide-6 and polyamide-1 1 are particularly preferred. Another preferred mixed polyamide consists of polyamide-6, polyamide -6.6 and either polyamide-1 1 or polyamide-12.

In a further preferred variant, the spinning shaft closes on its underside with the liquid surface of the cooling liquid of the spinning bath.

After leaving the liquid bath, the monofilaments are usually freed of adhering cooling liquid and aftertreated by optionally preparing, stretching and fixing. The monofilaments are then wound up.

The monofilaments produced according to the new so-called dry / wet melt spinning process are characterized by a smoother surface and a higher working capacity (defined as a product of the tenacity and maximum tensile strength).

Due to the defined air cooling described, especially if the preferred flow profi le is adhered to, a smooth surface of the threads is produced and the monofilament jacket is gently cooled, so that the core-jacket structure is less than in the usual processes (spinning through a small air gap in the liquid bath) is pronounced.

In particular, the described spinning method according to the invention is necessary at a higher production speed of 600 to 3000 m / min in order to achieve that of the

Monofilament to achieve the required textile properties. The melt spinning process according to the invention is preferably used for the production of fishing wires, in particular for high-strength transparent fishing wires and for the production of technical monofilaments, in particular at a higher production speed (> 600 m / min) or an increased number of die holes

The transparency and, above all, the knot strength of, for example, fishing wires from the monofilaments are significantly improved by the spinning process according to the invention

Another object of the invention is a device for carrying out the inventive method consisting of a melt spinning head with spinneret, a spinning shaft with a blowing unit and suction unit, a liquid bath with thread deflection and flow breakers, scrapers and an adhesive liquid suction, optionally a preparation point , one or more stretching units, in particular for hot stretching, a fixing zone and winding points. The device is characterized in that the spinning shaft surrounds or in particular encloses the space between the spinning head and the liquid surface of the cooling liquid bath in a gas-tight manner

In particular, gas nozzles for blowing the monofilaments in the spinning shaft are provided on one side of the shaft, which are optionally provided with flow comparators in the area of the monofilaments

In a preferred embodiment, the first blowing nozzle in the spinning shaft below the spinning nozzle is a flat nozzle with an adjustable nozzle gap. All the air nozzles in the spinning shaft can preferably be regulated separately, so that the air streams can be adjusted in accordance with the required air flow profile

A variant of the device has a ring nozzle with flow comparators for comparing the gas velocity profile in front of the nozzle for blowing on the monofilaments in the spinning shaft The spun thread can be sucked off. A device is preferred in which the suction is arranged in the spinning shaft opposite the air inlet nozzles The invention is explained in more detail below with reference to FIGS. 1 to 3 without restricting the invention in detail

Show in the figures.

Figure 1 is a schematic view of the front part of the spinning device according to the invention

Figure 2 An enlarged view of the spinneret and cooling bath from one

Variant of the spinning device according to the invention shown in FIG. 1

Figure 3 is a schematic view of the entire spinning device with

Aftertreatment line

REPLACEMENT BLAπ (RULE 26) Examples

General process description

The polymer melt is fed via a line to the melt spinning head 17 with the spinneret 1 (see FIG. 1). The spinning shaft 2 has an air-blowing unit 3 and suction unit 4, which are used for feeding and discharging the

Provide cooling air and face each other as shown in Fig. 1. An additional slot nozzle 19 with flow equalizers 21 for uniformizing the gas velocity profile in front of the nozzle 19 is attached above the blowing unit.

In a variant of the device according to FIG. 2, the suction unit 4 has a suction channel 22 which extends in a ring around the spinning shaft 2 and which causes the spatially uniform escape of the spinning gas. Instead of the slot nozzle 19 there is an annular nozzle 20 and as a blowing unit 3 there are annular nozzles with flow equalizers.

The thread sheet 23 of the monofilaments is pre-cooled in the spinning shaft 2 in both variants by blowing with air.

The thread sheet 23 is then further cooled and solidified in a liquid bath 5. A thread deflection 6 causes the gentle change in direction of the running direction of the thread sheet 23 by means of a plurality of deflecting rods. In the cooling bath, flow breakers 16 calm the cooling bath liquid at high production speed in order to avoid turbulence in the cooling bath liquid due to the liquid carried by the monofilaments and to prevent the still soft monofilaments from beating (see FIG. 1). Since the monofilament cooling bath liquid is entrained from the cooling bath 5 at a high outlet speed, liquid wipers 7 are attached behind the outlet of the monofilaments 23 from the cooling bath liquid and in front of the pair of traction rollers 8, which, like a further adhesive liquid suction device 9, remove the entrained cooling bath liquid from remove the monofilament 23. The spinning device also has a preparation site 10 and subsequent suction 11 for excess preparation, a hot stretching zone 13, a fixing zone 14 and winding machines 15 for winding the monofilaments. The running speed of the

REPLACEMENT BLAπ (RULE 26) Roller septets 12, 24 and 25 determine the distortion in the area of the hot stretching zone 13 and the fixing zone 14 (see FIG. 3).

The spinning shaft 2 of the spinning device is designed in both device variants in such a way that the spinning shaft 2 gas-tightly encloses the space between the spinning head 17 and the liquid surface 18 of the cooling liquid bath 5 in which the monofilaments are formed.

A device in the variant according to FIG. 1 was used for the following test examples. However, the spinning shaft 2 had not been used to enclose the space between the spinning head 17 and the liquid surface 18 in a gas-tight manner. One or three standing on top of each other were used for blowing

Nozzles 19 and 3a, 3b used. The width of the nozzles covered the width of the thread sheet.

The nozzle 19 was a slot nozzle with the height indicated in each of the examples. The nozzles 3a and 3b were nozzles equipped with a more uniform flow, the height of which covered the remaining height below the spinning nozzle.

example 1

Monofilaments with a diameter of 0.40 mm were produced from a commercially available copolyamide with the designation Ultramid C 35 (manufacturer: BASF AG, Ludwigshafen) under the standard conditions described above.

The distance between the exit of the melt from the spinning nozzle opening and the surface of the cooling medium (water) was 60 mm.

A slot nozzle 19 with a slot height of 25 mm was installed in this zone, with the aid of which the monofilaments between the nozzle outlet and the inlet into the cooling medium were blown with air in a defined manner. The linear and knot strength measured on the monofilaments obtained is as indicated in Table 1

For the comparative example in Table 1, there were no blowing nozzles. The thread sheet was in the area between spinning head 17 and

ERSATZBUπ (RULE 26) Cooling liquid surface is guided through ambient air over a distance of 15 mm

Table 1

Example 2

Monofilaments with a diameter of 0.20 mm were produced from a commercially available polyamide of type Durethan B 31 (manufacturer BAYER AG, Leverkusen) under the standard conditions described. The distance between the melt exit from the spinneret opening and the surface of the cooling medium was ( Water) 280 mm

For the comparative example in Table 2, no blowing nozzles were used. The thread sheet was guided in the area between the spinner head 17 and the cooling liquid surface over a distance of 15 mm through ambient air

Table 2

REPLACEMENT BLAπ (RULE 26) Example 3

Monofilaments of different diameters were produced from a commercially available copolyamide with the designation Ultramid C 35 (manufacturer BASF AG, Ludwigshafen) under the standard conditions described. The distance between the exit of the melt from the spinneret opening and the surface of the cooling medium (water ) 60 mm

In this zone, a protective nozzle 19 with a slot height of 25 mm was installed, with the aid of which the monofilaments between the nozzle outlet and the entry into the cooling medium were blown with air in a defined manner. For the comparative example in Table 3, the installation of blowing nozzles was dispensed with The

In the area between the spinning head 17 and the cooling liquid surface, a thread sheet was guided over a distance of 15 mm through ambient air. The linear and knot strength measured on the monofilaments obtained was as follows

REPLACEMENT BLAπ (RULE 26) Table 3

REPLACEMENT BLAπ (RULE 26)

Claims

1 Continuous process for producing monofilament thread 23 with a diameter of 60 μm to 2000 μm from thread-forming thermoplastic polymers by melt spinning the molten polymer from a spinning head 17, blowing the thread 23 sideways with a cooling gas in a spinning shaft 2, cooling the thread formed in a cooling liquid bath 5, removal of the adhering cooling liquid 24, optionally preparation, stretching of the thread 23 in one or more stages, fixing and winding up the thread 23 at an outlet speed of the fixed thread 23 of 100 to 4000 m / min, characterized in that the cooling gas has a temperature of 0 to 50 ° C, that the cooling gas shows a defined speed profile and that the cooling liquid has a temperature of -10 to 150 ° C

2 The method according to claim 1, characterized in that the cooling gas flows from blow nozzles 20, which are arranged in a ring around the thread 23 in the spinning shaft in the spinning shaft 2, and that the cooling gas is sucked out together with the outgassings from the spun thread 23 below the blow nozzles 20

3 The method according to claim 1, characterized in that the cooling gas enters through the blowing unit 3, which is arranged in the spinning shaft 2 on one side and that the cooling gas is sucked out together with the outgassings from the spun thread 23 relative to the unit 3

4 Process according to claims 1 to 3, characterized in that the spinning shaft 2 closes the thread 23 between the spinning head 17 and liquid bath 5 from the environment

5 The method according to any one of claims 1 to 4, characterized in that the spinning shaft 2 has a length of 2 to 200 cm, in particular from 8 to 60 cm

REPLACEMENT BLAπ (RULE 26) Method according to one of claims 1 to 5, characterized in that the air speed in the spinning shaft 2 measured transversely to the direction of withdrawal of the threads 23 at a distance of 0.5 to 6 cm from the spinneret 1 0.05 to 10 m / sec, is in particular 0.1 to 2 m / sec

Method according to one of claims 1 to 6, characterized in that the spinning gas velocity in the spinning shaft 2 at a distance of 6 to 200 cm from the spinneret 1 is from 0.001 m / sec to 1 m / sec, in particular from 0.01 to 0.2 m / sec

Method according to one of claims 1 to 7, characterized in that the threads 23 are blown with tempered air at a temperature of 0 to 50 ° C, in particular 10 to 30 ° C in the spinning shaft 2

Method according to one of claims 1 to 7, characterized in that the cooling gas blown into the spinning shaft 2 together with the outgassings from the spun threads 23 is sucked off uniformly over the entire spinning shaft 2 with respect to the entry of the cooling gas

Method according to one of claims 4 to 9, characterized in that the suction produces a pressure difference of 10 to 100 Pa in the spinning shaft 2 with respect to the ambient pressure

Method according to one of claims 1 to 10, characterized in that a polyamide, polyethylene terephthalate,

Polybutylene terephthalate, polypropylene or polyethylene, in particular a polyamide is used

Device for performing the method according to one of claims 1 to 1 1, consisting of a melt spinning head 17 with a spinneret 1, a spinning shaft 2 with a blowing unit 3, a suction unit 4, a

Liquid bath 5 with thread deflection 6 and flow breakers 12, wipers 7 and an adhesive liquid suction 9, optionally a spinning preparation station 10, one or more drawing units 12, in particular for hot drawing, a fixing zone 14 and winding stations 15, characterized in that the spinning shaft 2 den room

REPLACEMENT BLAπ (RULE 26) surrounds between the spinning head 17 and the liquid surface 18 of the cooling liquid bath 5 in the region of the monofilaments 23

Apparatus according to claim 12, characterized in that blowing nozzles in the blowing unit 3 for blowing the threads 23 in the spinning shaft 2 are arranged on one side and provided with flow comparators 21

Apparatus according to claim 12 to 13, characterized in that the first nozzle of the blowing unit 3 in the spinning shaft 2 below the spinneret 1 is an adjustable flat nozzle

Device according to claim 12 to 14, characterized in that all

Nozzles of the spinning shaft 2 can be regulated separately in order to adjust the gas speed of the nozzles in accordance with the required air flow profile

Device according to claim 12, characterized in that an annular nozzle with flow comparators is provided in the chimney shaft 2 as the blowing unit 3 of the threads 23

Apparatus according to claim 12 to 16, characterized in that an annular suction 22 is provided in the spinning shaft 2, via which the cooling gas blown into the spinning shaft 2 together with the outgassings from the spun thread 23 can be sucked out below the blowing nozzle

Device according to claims 12 to 16, characterized in that the spinning shaft 2 contains cooling gas suction devices lying opposite the air inlet nozzles

REPLACEMENT BLAπ (RULE 26)