GB1586242A

GB1586242A - Method and apparatus for producing monofil fleece

Info

Publication number: GB1586242A
Application number: GB4206677A
Authority: GB
Original assignee: KARL MARX STADT TECH TEXTIL
Current assignee: KARL MARX STADT TECH TEXTIL
Priority date: 1976-10-11
Filing date: 1977-10-10
Publication date: 1981-03-18
Also published as: FR2371537B1; SU896112A1; DD128204B1; DD128204A1; FR2371537A1; NL7710970A; DE2742068A1; CS199101B1

Description

(54) METHOD AND APPARATUS FOR PRODUCING MONOFIL FLEECE (71) We, VVB TECHNISCHE TEX TILIEN KARL-MARX-STADT, Wissenschaftlich-Technisches Zentrum Technische Textilien Dresden, of 6 Hohe Strasse, Dresden, German Democratic Republic, a Corporation organised under the laws of the German Democratic Republic, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to bye particularly described in and by the following statement: The present invention is concerned with the manufacture of monofil fleece by the melt or solution spinning principle.

In order to produce monofil fleece, the known .methods provide melt spinning equipment in which threads emerge individually from spinning orifices and are picked up by streams of air, cooled and finally deposited to form a fleece. In corresponding apparatus, the air is used as a cooling, tempering and propellant agent.

The need to obtain, for various fields of use, monofilaments which are stretched to the greatest possible extent, has resulted in the construction of complicated propellant equipment (see, for example, German Patent Specifications Nos. 1,303,569; 1,282,5901,785,158 and 2,048,006), which make exacting demands upon mechanical production and also occasion considerable expense in terms of operation. For example, from information given in German Patent Specification No. 2,048,006, a consumption of air compressed to about 3 kp/sq. cm., of 1200 nom.cu.m./hr. is indicated for a fleece l metre wide. If round spinnerets are used, as described in German Patent Specification No. 1,785 158. then the air consumption. in terms of air compressed to 22 kp/sq. cm., is about 1400 nom.cu.m./hr. for a thread count of 1500. deposited in the normal way to form a fleece 1 metre wide. In this case, the method of propulsion leads to the use of many individual air streams which produce a plurality of groups of threads which it is very difficult or even impossible to bring together to form a uniform flat structure having regular textile-physical properties. The considerable expense of mechanical production and the considerable cost of producing large quantities of compressed air are significant disadvantages of these known methods.

It has also already been suggested to group the spun threads together into a sliver and stretch them over godets . at different peripheral speeds. The stretched fibres are then spread out again, in that streams of gases emerging from an arcuate slotted jet act on the sliver and spread this out in a fan shape, after which it is deposited to form a fleece on a perforated support surface. The disadvantage of this method is that in the event of possible thread breakage and/or electrostatic charging of the threads, lap formation may take place, which will jeopardise the stability of the process.

It is also known for a group of threads to be drawn together with the air into corresponding nozzles extending over the entire working width.

The application of the suction drawing method has the advantage that regular monofil fleeces can be produced over considerable working widths. The expenditure involved in producing and maintaining the suction draught is relatively low, which also speaks in favour of using this method.

In the past, the premise has been that more or less laminar states need to be maintained in the flowing gas while it is passing through a suction drawing nozzle in order to achieve the highest possible rates of flow at the negative pressure applied below the nozzle and, furthermore, to avoid entanglement in the monafilaments passing through the nozzle.

Such a laminar flow of a gaseous medium in a suction drawing nozzle exerts a relatively low stretching function on the monofilaments extruded.

In this way, only fleeces of average strength properties for relatively high elongations and monofilament thicknesses can be produced, so that the fields of application are restricted.

All in all, it can be said that the currently known methods of producing monofil fleece either entail very high technical expenditure and, in addition, high costs for operating the compressor plant or, as in the case of the simpler and less expensive suction drawing methods, they suffer from a limited application of the product.

It is an object of the present invention to provide a method and an apparatus for the production of monofil fleece of high strength and low elongation in all directions of loading, lower monofilament thicknesses and higher surface coverage, combined with minimal cost.

A further object of the present invention is, to the greatest possible degree, to provide advantageous product properties, such as were hitherto attainable only by means of costly propellant air processes or the godet principle, which was susceptible to breakdown, preferably while retaining the basic principle of the simple and cheaper suction air process. In particular, the stretching effect which can be achieved with the suction air is to be increased by appropriate means.

Accordingly, the present invention consists in a method of producing monofil fleece by the melt or solution spinning principle, the spun group of monofilaments being accelerated in a suction drawing nozzle, and are, at the same time, stretched and are deposited on a perforated belt to form a fleece, wherein, inside the nozzle, on one side or on both sides, in addition to the suction flow which is produced below said belt, a gas at a velocity of 200 to 900 m/s is blown from orifices of gas feed means arranged in said nozzle on to the monofilaments at an angle a of 5 to 90" with regard to the direction of thread run, the total quantity of the gas used not exceeding 200 cu.m/hr. and metre of working width. Thus, the threads are deflected in a desired direction, preferably within the suction drawing nozzle. Furthermore, the addition of the gas produces an increase in the degree of turbulence in the nozzle, amplifying the drawing and stretching forces which are exerted on the monofilaments.

By feeding the stream of gas from oppositely disposed or mutually offset openings or at different heights in the nozzle, many varia tions are possible in order to optimise the principle of the present invention.

By varying the rate and direction of flow, for example by pulsation in the various direc tions of flow. it is possible further to improve the textile-physical properties of the flat structure produced. The stream of gas must be brought into the nozzle in such a way that the sliding surfaces for the drawing air and the friction on the groups of threads along the walls of the nozzle are not substantially adversely affected.

Appropriate mechanical arrangements provide for a briefly periodic change of the blow-out conditions in the two feed devices in respect of each other.

For a better understanding of the present invention, one embodiment thereof will now be described in more detail, with reference to the accompanying drawings, in which: Fig. 1 shows a diagrammatic view of the most important parts of a monofil fleece production plant from the transition. of the extruded threads to their being deposited in a fleece; Fig. 2 shows the essential details for accomplishing the present invention in the form of a suction dråwing nozzle; and Fig. 3 shows a section through the parts of a suction drawing nozzle along line A-A of Fig. 1 showing an air supply device, the outlet orifices of which are directed at an angle ss and p 2 two the plane of a group of threads.

The device shown diagrammatically in the drawings constitutes a preferred embodiment, particularly in relation to the arrangement of the supply of gas in a knownsuction drawing nozzle. Groups of monofilaments 2 are extruded from the spinneret arrangement 1. By means of a suction device 9, the groups of threads are drawn in known manner into a suction zone 3, passed through-a suction drawing nozzle 7 and deposited on a belt 8 as a fleece 10. Incorporated inside the members 4a and 4b of the nozzle 7 are gas feed ducts Sa and Sb which are provided with orifices 6. The gas feed ducts 5a and 5b are tubes which are rotatably mounted in the profiles of the members 4a and 4b in corresponding grooves 11. By applying the additional gas stream at high speeds, the monofilaments are deflected and are accelerated substantially more strongly by the suction draught which prevails. It is advantageous to blow the stream of gas out from both members 4a and 4b. Both the angle to the direction of thread run a and also the angle in relation to the plane of the group of threads P S < P2, as well as the location of the orifices 6 in the two members 4a and 4b in respect of each other, can be varied so that advantageous effects can be achieved particularly in respect of the draw off forces and also depositing of the threads.

The blow out conditions may be influenced by displacing the gas feed ducts 5a and 5b transversely to the thread run by an amount d, in synchronism or in opposition with different frequency.

WHAT WE CLAIM IS: 1. A method of producing monofil fleece

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. extruded. In this way, only fleeces of average strength properties for relatively high elongations and monofilament thicknesses can be produced, so that the fields of application are restricted. All in all, it can be said that the currently known methods of producing monofil fleece either entail very high technical expenditure and, in addition, high costs for operating the compressor plant or, as in the case of the simpler and less expensive suction drawing methods, they suffer from a limited application of the product. It is an object of the present invention to provide a method and an apparatus for the production of monofil fleece of high strength and low elongation in all directions of loading, lower monofilament thicknesses and higher surface coverage, combined with minimal cost. A further object of the present invention is, to the greatest possible degree, to provide advantageous product properties, such as were hitherto attainable only by means of costly propellant air processes or the godet principle, which was susceptible to breakdown, preferably while retaining the basic principle of the simple and cheaper suction air process. In particular, the stretching effect which can be achieved with the suction air is to be increased by appropriate means. Accordingly, the present invention consists in a method of producing monofil fleece by the melt or solution spinning principle, the spun group of monofilaments being accelerated in a suction drawing nozzle, and are, at the same time, stretched and are deposited on a perforated belt to form a fleece, wherein, inside the nozzle, on one side or on both sides, in addition to the suction flow which is produced below said belt, a gas at a velocity of 200 to 900 m/s is blown from orifices of gas feed means arranged in said nozzle on to the monofilaments at an angle a of 5 to 90" with regard to the direction of thread run, the total quantity of the gas used not exceeding 200 cu.m/hr. and metre of working width. Thus, the threads are deflected in a desired direction, preferably within the suction drawing nozzle. Furthermore, the addition of the gas produces an increase in the degree of turbulence in the nozzle, amplifying the drawing and stretching forces which are exerted on the monofilaments. By feeding the stream of gas from oppositely disposed or mutually offset openings or at different heights in the nozzle, many varia tions are possible in order to optimise the principle of the present invention. By varying the rate and direction of flow, for example by pulsation in the various direc tions of flow. it is possible further to improve the textile-physical properties of the flat structure produced. The stream of gas must be brought into the nozzle in such a way that the sliding surfaces for the drawing air and the friction on the groups of threads along the walls of the nozzle are not substantially adversely affected. Appropriate mechanical arrangements provide for a briefly periodic change of the blow-out conditions in the two feed devices in respect of each other. For a better understanding of the present invention, one embodiment thereof will now be described in more detail, with reference to the accompanying drawings, in which: Fig. 1 shows a diagrammatic view of the most important parts of a monofil fleece production plant from the transition. of the extruded threads to their being deposited in a fleece; Fig. 2 shows the essential details for accomplishing the present invention in the form of a suction dråwing nozzle; and Fig. 3 shows a section through the parts of a suction drawing nozzle along line A-A of Fig. 1 showing an air supply device, the outlet orifices of which are directed at an angle ss and p 2 two the plane of a group of threads. The device shown diagrammatically in the drawings constitutes a preferred embodiment, particularly in relation to the arrangement of the supply of gas in a knownsuction drawing nozzle. Groups of monofilaments 2 are extruded from the spinneret arrangement 1. By means of a suction device 9, the groups of threads are drawn in known manner into a suction zone 3, passed through-a suction drawing nozzle 7 and deposited on a belt 8 as a fleece 10. Incorporated inside the members 4a and 4b of the nozzle 7 are gas feed ducts Sa and Sb which are provided with orifices 6. The gas feed ducts 5a and 5b are tubes which are rotatably mounted in the profiles of the members 4a and 4b in corresponding grooves 11. By applying the additional gas stream at high speeds, the monofilaments are deflected and are accelerated substantially more strongly by the suction draught which prevails. It is advantageous to blow the stream of gas out from both members 4a and 4b. Both the angle to the direction of thread run a and also the angle in relation to the plane of the group of threads P S < P2, as well as the location of the orifices 6 in the two members 4a and 4b in respect of each other, can be varied so that advantageous effects can be achieved particularly in respect of the draw off forces and also depositing of the threads. The blow out conditions may be influenced by displacing the gas feed ducts 5a and 5b transversely to the thread run by an amount d, in synchronism or in opposition with different frequency. WHAT WE CLAIM IS:

1. A method of producing monofil fleece

by the melt or solution spinning principle, the spun group of monofilaments being accelerated in a suction drawing nozzle, and are, at the same time, stretched and are deposited on a perforated belt to form a fleece, wherein, inside the nozzle, on one side or on both sides in addition to the suction flow which is produced below said belt, a gas at a velocity of 200 to 900 m/s is blown from orifices of gas feed means arranged in said nozzle on to the monofilaments at an angle a of 5 to 900 with regard to the direction of thread run, the total quantity of the gas used not exceeding 200 cu.m/hr. and metre of working width.

2. A method according to claim 1, wherein the blow out condition are influenced by displacing the gas feed means on both sides in the nozzle transversely to the thread run by an amount d, in synchronism or in opposition with different frequency and/or by pulsation in intensity.

3. A method according to claim 1 of producing monofil fleece, substantially as hereinbefore described and with reference to the accompanying drawings.

4. Apparatus for carrying out the method according to claim 1, comprising a suction drawing nozzle which carries inside on one side or on both sides a tubular gas feed duct which is mounted in a groove formed in the nozzle so as to be rotatable through an angle a about the axis of the tube, blow out orifices being provided in the or each gas feed duct.

5. Apparatus according to claim 4, wherein the diameter of the blow out orifices located on the same side is in a ratio of 1:5 to 1:50 in respect of their spacingy.

6. Apparatus according to any of claims 4 or 5, wherein the gas feed ducts on both sides can be displaced longitudinally in the nozzle by an amount d to < y.

7. Apparatus according to any of claims 4 to 6, wherein the gas feed ducts are disposed at different heights.

8. Apparatus according to any of claims 4 to 7, wherein the blow out orifices are directed at angles Pl < P2 to the plane of a group of threads.

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