GB1579757A

GB1579757A - Spinning lead for synthetic fibres of thermoplastic polymers

Info

Publication number: GB1579757A
Application number: GB3591677A
Authority: GB
Original assignee: Akzo NV
Current assignee: Akzo NV
Priority date: 1976-09-04
Filing date: 1977-08-26
Publication date: 1980-11-26
Also published as: JPS5370118A; NL7708893A; JPS61441B2; ATA553477A; LU78068A1; IT1079352B; AT349602B; FR2363645B1; CH623610A5; FR2363645A1

Abstract

In a spinning head with a curved metal foil (6) which is inserted into a cylindrical bore (3) of a housing (1) and which has spinning orifices (10) in the region of a recess (5) of the housing (1), there are provided, in order to reduce the specific space requirement, simplify the spinneret exchange and improve the spinneret sealing, at least two bores (3) which extend parallel to the underside of the housing (1), and into each of which a metal foil (6) bearing under prestress against the bore wall is inserted. The recesses (5) are preferably designed as grooves which are worked into the underside of the housing (1) transversely to the bores (3) and parallel to one another. As a result of the insertion of further metal foils and of a convexly curved cylindrical ram pressing against these, the metal foils and ram having guide channels and/or passage orifices for at least two spinning components, spinning heads suitable for the spinning of multi-component threads can be produced. <IMAGE>

Description

(54) SPINNING HEAD FOR SYNTHETIC FIBRES OF THERMOPLASTIC POLYMERS (71) We, AKzo N.V. a body corporate organised under the laws of the Netherlands, of Arnhem, Netherlands, 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 be particularly described in and by the following statement: This invention relates to a spinning head for synthetic fibres of thermoplastic polymers; more particularly, it relates to a spinning head comprising a housing having a recess and a cylindrical passage in which is located a metallic foil having spinning openings in the region of the recess.

U.S. Patent No. 3,964,855 describes such a spinning head in which two preformed channel shaped thin sheets provided with spinning openings are inserted in a tubular housing provided with guide channels for the sheets, and the housing is screwed up on the front face with throw-over nuts. An inner melt chamber formed ed between the two preformed channel-shaped sheets and the throw-over nuts is sealed on the one hand by gaskets, and by the edges of the sheet(s) inserted in the groove of the housing.

This design gives rise to problems of sealing in the area of the grooves of the housing caused by the mechanical fixing of the edges of the sheets in the grooves. These problems cannot be overcome by the flexibility of the thin sheets and/or the pressure of the melt against the sheets. Another disadvantage of this known design is the relatively high requirement in space, since only one cylindrical opening is provided per housing, and the fact that the freshly formed threads have to be drawn off in opposite directions, usually horizontally in each case.

Another known spinning head (see U.K.

Patent No. 1,264,346-German Offenlegungsschrift No. 1,942,197) is provided with a metallic foil, having spinning openings, of substantially rectangular shape instead of the conventional die plates or die inserts. In this known design, the metallic foil is stretched between the actual spinneret body or a clamping plate mounted thereon and a cover which may be screwed up with the spinneret body, building up an initial tension in an easily curved shape.

In order to fix this metallic foil securely and tightly, the cover pressing it against the spinneret body is driven home all around by means of numerous screw threaded connections. The metallic foil is preferably surrounded by a crimp-shaped indentation in which a gasket, for example, may be inserted. These known spinning heads have several considerable disadvantages. Since the rectangular metallic foils have to be stretched all around so that they are resistant to pressure, flange joints have to be provided all around, and these flange joints require a large amount of space from the point of view of construction, on the one hand, and require a great amount of time for exchanging the metallic foil, on the other hand.Furthermore, these known spinning heads are only suitable when relatively low spinning pressures are used, such as those prevailing, íor example, when spinning polyacry lonitrile solutions.

An object of the present invention is to overcome the disadvantages described above and to provide a spinneret which operates positively, even at high spinning pressures and high temperatures of the type which occur during melt spinning, occupies a small amount of space and is quickly exchangeable The present invention provides a spinning head for synthetic fibres of thermoplastic polymers which comprises a housing having at least two cylindrical passages having diameters of less than 301my running parallel to the underside of the housing, each of the cylindrical passages forming a recess in the underside of the housing and a metallic foil less than 0.5mm thick being located in each cylindrical passage, the foil con tacking the wall of the cylindrical passage and lining at least part of the curved surface of the cylindrical passage under initial tension and having spinning orifices in the region of the recess and aligned with the recess, and the housing defining a pathway for the supply of molten thermoplastic polymer to each of the cylindrical passages.

The force of the initial tension of the metallic foil is utilised for improving the seal of the melt chamber againts the environment.

Moreover, it is possible to use metallic foils which do not require further processing apart from the provision of the spinning openings (as carried out, for example, in photochemical methods) as well as, in some cases, prelinunary bending in order to guarantee that they are applied evenly OO the wall and are inserted more easily into the passages. These objects not only result in spinning heads which are only suitable for spinning a single spinning component, for example a polyester melt or a polyamide melt and thus produce so-called mono-component fibres", but also result in spinning heads which are suitable for producing multi-component fibres from at least two spinning components.

The cylindrical passages are arranged at small distances from each other in one row or several rows running parallel to each other.

The cross-section of the cylindrical passages may be, for example, oval or semi-circular.

Regarding the diameter of a non-circular cylindrical passage, as will be appreciated by those skilled in the art, for example, in the case of a semi-circle, it remains the diameter, while in the case of an oval or ellipse it is the horizontal axis. However, the passages preferably have a circular cross-section which is the most simple to produce and which ensures an optimum position of the metallic foils adapted to the walls of the passages or to the walls of the hollow cylinder both with regard to solidity and to pressure.

The recesses on the underside of the housing may, for example, be produced by forming the cylindrical passages in sucli a way that part of the cross-section of the passage lies outside the housing and tlius projects over the underside of the housing. Another possibility is to manufacture the cylindrical passages to the underside of the housing and then to mill longitudinal grooves from the underside outwards parallel to the passages which grooves are deep enough to penetrate the passages.

The recesses are preferably formed by grooves which are produced in the underside of the housing, transversely to the cylindrical passages and parallel to each other.

In one embodiment of the present spinning head, hollow cylinders with recesses are arranged in the cylindrical passages. Metallic foils contact the internal walls of these hollow cylinders. The use of such hollow cylinders affords the advantage that they, together with the metallic foil, are easily exchangeable so that it is possible to adapt the recesses and arrangement of spinning openings to specific titres.

The term "metallic foils" in the context of the present invention means thin sheets of metallic materials which have sufficiently high strengths at normal spinning temperatures (which may reach about 300 ) and do not deform, in particular plastically. After bending the metallic foils and inserting them in the cylindrical passages, they should be quite rigid in the area of the recesses. The thickness of such metallic foils must not exceed the valve of 0.5 mm so that they may be easily bent (for inserting the metallic foils in the passages or in the hollow cylinder). Metallic foils which are less than 0.2 mm thick are preferably used.

Spinning openings of practically random size and of random shape may be worked in metallic foils of such thicknesses by, for example, photographic, electrochemical or electroerosive methods.

The radius of curvature of the walls of the cylindrical passages (in the case of circular cylindrical passages, the radius thereof) or of the walls of the hollow cylinder should preferably be smaller than 25 mm, more preferably smaller than 15 mm, un order to ensure that the metallic foils have high bending stresses.

In this way, a good seal in the region of the recesses for the thread passage, as well as sufficient rigidity against flexion is obtained in the axis of the cylinder. The seal at the end of the cylindrical passages may be obtained, for example, by providing the front faces of the housing with covers, using gaskets, for example, these covers being screwed on to the housing.

In one embodiment of the present spinning head, the cylindrical passages have channels for the passage of the melt which open laterally, as well as enlargements at the end and are connected in each case by means of a bolt having a head in one of these enlargements and a nut in the outer, the nut being screwed up from the opposite side and pressing seals against the hous ing. In this embodiment, the bolt simultaneously performs the function of a positive displacement type body which is surrounded by the melt and substantially prevents the formation of clearance volumes in the flow.

This bolt may preferably be adjustable in accordance with temperature, that is to say is provided with heating or cooling means which affect the temperature of the melt shortly before it is discharged.

In another embodiment of the present invention, the housing is formed in two parts, the metallic foil or the hollow cylinder surrounding tlle metallic foil being inserted in pockets in the two parts of the housing.

Other preferred embodiments of the present spinning head are suitable for producing multicomponent fibres. Thus, fibres having a side-byside structure (S/S type), as well as core-sheath structures (C/S type) with symmetrical or assymetrical build-up or matrix-fibril structures (M/F type) may be produced, while maintaining the solvent principle of the spinning heads which are suitable for the production of monocomponent fibres. Reference is made to P.A.

Koch, fibrous substance tables "Bicomponent fibres" February 1970 edition, chapter 1, with regard to the structure of such fibres.

These spinning heads which are suitable for producing multi-component fibres are characterised by at least one other metallic foil per passage, this other metallic foil being pressed against the metallic foil and being provided with guide channels and/or openings for the passage of the spinning components, and by a convexly curved block pressing against this other metallic foil or foils and having at least one guide channel for the spinning component or components.

The most varied fibre structures may be produced by means of the number of further metallic foils and the configuration thereof, in particular shape and size, as well as reciprocal allocation of the guide channels and/or openings for the passage of the spinning components therein, and by means of the configuration of the block and the allocation of the further metallic foils to the metallic foil provided with the spinning openings. Thus, side-by-side spun bi-component fibres may be produced by using only one other metallic foil provided with a number of guide channels which is identical to the number of spinning openings, and a block provided with two guide channels.

The spinning head according to the present invention is preferably provided with two other metallic foils, thus with a total of three superimposed metallic foils. Such designs ensure that core-sheath fibres are spun, these fibres particularly with assymetrical build-up owing to the potential crimpability being generally preferable to the side-by-side spun fibres. The rear (innermost) metallic foil usually has openings for the passage of the core component and the core is surrounded by the sheath component in the guide channels of the centre metallic foil before extrusion through the spinning openings of the foremost (outermost) metallic foil. The buildup of the core-sheath fibres may be influenced substantially by the position of the openings in the rear metallic foil.

Some embodiments of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a section through a housing provided with two cylindrical passages; Figure 2 is a section along the line AB in Figure 1; Figure 3 is a section along line C-D in Figure 2 with a cylindrical passage which is sealed off by means of a bolt acting as positive displacement body; Figure 4 is a section through the cylindrical passage sealed off with a bolt in Figure 3 with an inlaid metallic foil; Figure 5 and Figure 6 illustrate details of a metallic foil provided with spinning openings; Figure 7 is a detail view from underneath of a spinning head according to the present invention; Figure 8 is an enlarged detail of a metallic foil having a profiled spinning opening;; Figure 9 is a section through a two-part spinning head in which the metallic foils rest in pockets; Figure 10 is a longitudinal section through a hollow cylinder suitable for receiving the metallic foil; Figure 11 is a section along line E-F in Figure 10; Figure 12 illustrates a laterally charged spin ning head provided with the hollow cylinder according to Figures 10 and 11; Figure 13 illustrates a spinning head accord ing to the present invention for producing slde by-side spun fibres; Figure 14 illustrates a metallic foil adapted to this spinning head and having guide channels; Figure 15 illustrates a metallic foil adapted to this spinning head and having spinning open ings; Figure 16 illustrates a spinning head for the production of core-sheath fibres in which two components are supplied via the stamp;; Figure 17 illustrates a metallic foil adapted to this spinning head and having spinning open inns; Figure 18 illustrates a metallic foil adapted to this spinning head and having guide channels for the sheath component; Figure 19 illustrates a metallic foil adapted rof this spinning head and having openings for the passage of the core, as well as for the sheath component; Figure 20 illustrates another spinning head for producing core-sheath fibres; Figure 21 illustrates a metallic foil adapted to this spinning head with spinning openings; Figure 22 illustrates a metallic foil adapted to this spinning head with guide channels for the sheath component; and Figure 23 illustrates a metallic foil adapted to this spinning head with openings for the passage of the core component.

Figure 1 illustrates a housing of a spinning head according to the present invention. The housing has a hole 2 for receiving, for example, a screen packing or a support plate and cylindrical passages 3 for receiving metallic foils, as well as channels 4 for the passage of a melt.

Recesses 5 for the passage of fibre run from the underside of the housing 1 transversely to the cylindrical passages 3. These recesses are in this embodiment grooves of rectangular cross-section, and they penetrate the passages 3 at certain points. In the embodiment illustrated in Figures 1 to 3, the housing is round, but if more than two cylindrical passages are provided in one spinning head, a rectangular housing is preferably used.

The cylindrical passages 3 have enlarged portions 3' at the ends thereof. As shown at the top of Figure 3, each passage 3 and enlarged portion 3 receives a bolt 7 and a nut 8 which are screwed together once a metallic foil 6 has been inserted and fixed in the cylindrical passage 3, and are thus pressed firmly against the housing 1 via seals. The nut 8 is secured by means of a pin 9 which engages in a groove 3 By suitably constructing the bolt 7, the flow of melt in the cylindrical passages 3 may be influenced, in particular clearance volumes in the melt are prevented from forming.

The recesses 5 are visible and may be seen in the lower cylindrical passage 3 in Figure 3.

Figure 4 illustrates a detail of a spinning head similar to that of Figures I to 3, in which there are no recesses 5. Figure 4 clarifies the allocation according to the present invention of cylindrical passage 3 which is penetrated by the recesses 5 at sone points. and metallic foil 6 which has spinning openings 10 in tlie area of these penet rations. The tlilllensions of the metallic foil G anti tile spinning openings are not to scale.

Figure 5 illustrates a metallic foil 6 having spinning openings 10 of circular cross-section arranged in three parallel rows. Tile diameter of the spinning openings 10 is, for example, 0.25 n1,11 and tile spacing "a" from 1.5 to 2)2!?t The nietallic foil 6 showil ill Figure 6 is suitable for a spinning Iicad which as shown in Figure 7, has recesses 5 running parallel to each other from the underside of the housing 1 transversely to the cylindrical passages 3. The metallic foil 6 has spinning openings 10 in the area of the recesses 5.

Figure 8 illustrates a detail of a metallic foil 6 having Y-shaped spinning opening í I 11 A con- siderable advantage of the metallic foil used in accordance with the present invention lies in the fact that spinning openings of practically random, complicated shapes and random sizes may be produced in a simple and very inexpensive channel. Thus. it is also feasible to compose profile spinning openings of several slits and/or finest passages.

The spinning head according to tile present invention enables tlic metallic foil 6 to be Cx- changed (quickly at spinning openings or 'viten the spinning foil is changed. 13y selecting suit- able diittensions for the cylindrical passages 3, as well as by using suitable materials for the metallic foils 6, an initial tension force niap be produced witicit exerts a sufficiently itigh pressure on the walls of the cylindrical passages 3 so that the die is not pervious before starting spinning. Widen subjected to tite full pressure of tlic melt, the metallic foil 6 is pressed against the housing 1 and sealed autonlatically.

The automatic seal is further improved by maintaining bar-like supports between the recesses 5 as shown in Figure 7. In tliis way.

relatively long rows of spinning openings 10 may be formed with a single metallic foil. and the normal high pressure during melt spinning may be taken up by the housing.

Figure 9 illustrates a preferred two-part embodiment of a spinning head according to the present invention. The two halves of the housing 12; 13 are pressed together by screw connections (not shown). As in the spinning head shown in Figure 3, the cylindrical passages, ill this embodiment formed as pockets 14; 15 have recesses 5 for tile passage of the fibre. Titey are registered with the spinning openings 10 of the metallic foil 6 which is inserted into the pockets 14;and 1 5 is sealed from these pockets at the end. Tliis embodiment is very desirable from the sealing point of view.

In the embodiments described above, the metallic foils 6 are always directly inserted in the cylindrical passages 3 in the housing 1.

However, as shown in Figures 10 and 11, it is also feasible to insert the metallic foil 6 in a hollow cylinder 16 which is easy and cheap to produce, and to insert this unit into a prepared cylindrical passage 3 of the spinning head.

Recesses 5' for the passage of the fibre may be very easily provided in such a hollow cylinder 16, which may be closed at a front end, with the result that large openings 17 which may be produced simply as groove-shaped recesses may be provided on the housing 1 itself, (e f: Figure 12). The housing 1 illustrated in Figure 12 has a channel 18 for distributing the itielt , troll1 which channel branch lines supply the individual spinning positions.

In this case, the melt is supplied to the front of the hollow cylinder 16 with recesses 5' and inserted metallic foil 6, this hollow cylinder 16 being inserted in to tite cylindrical passage 3 and pressed against the feed side of the housing 1 by means of a feed screw 20 and sealed there.

The use of units consisting of hollow cylinders 16 with recesses 5' in which the metallic foil 6 is inserted has the great advantage of enailing the recesses and arrangement of spinning openings to be adapted to specific titres as these units may be exchanged for other similar units.

The spinning heads shown in Figures 13 to 23 are suitable for the production of fibres con1posed of two spinning components.

The spinning head illustrated in Figure 13 comprises the housing 1, in which cylindrical passages are arranged in parallel to each other and parallel to the under-side of the housing 1.

Only one passage 3 is shown. A metallic foil 6 with spinning openings 10 is placed under initial tension against the wall of the passage 3.

The housing 1 has groove-shaped recesses 5 in the area of the spinning openings 10. Another metallic foil 2' is placed in contact with the initial tension. This other metallic foil 2' has a guide channel 7' for each spinning opening 10 of the metallic foil 6. A convex block 11', the shape of which is adapted almost to the cylindrical passage 3, presses the metallic foils 2', 6 against the wall of the passage. The block 11 has guide channels 12', 13' for the two spinning components which are fed to the feed pipe 14' one axially through the borehole 3 and the other perpendicularly through the feed channel 15'.

Figures 14 and 15 show the metallic foils 2' and 6 respectively adapted to the spinning head in Figure 13. While metallic foil 6 has spinning openings 10 (seven in this case), guide channels 7 (seven in this case also) are provided in metallic foil 2' and are congruent with the spinning opening 10 (elf. Figure 13).

The spinning head in Figure 13 functions in the following manner: A first spinning component (I) supplied through the central feed channel 15' reaches the guide channel 7' of the metallic foil 2' via the feed channel 13' and flows towards the spinning opening 10. A second spinning component (II) supplied axially through passage 3 reaches the feed channel 7 via feed channel 12' and also flows towards the spinning opening 10 where it meets spinning component I and is extruded with the latter with the formation of fibres having a side-byside structure.

Bi-component fibres having a core-sheath structure may by produced using the spinning head shown in Figure 16. Another metallic foil 6 having spinning openings 10 (eight in this case) rests outside in a cylindrical passage 3 of the housing 1 and the housing 1 has a grooveshaped recess 5 in the range of this metallic foil 6. The central metallic foil 2' having guide channels 7' lies between the outermost metallic foil 6 and an inner metallic foil 8' provided with openings 9' and 18'. Three superimposed metallic foils 6, 2' and 8' (shown individually in Figures 17 to 19) are pressed against the wall of the passage 3 by a block 11'. The core component is supplied to the feed pipe 14' via the feed channel 15' and reaches the opening 9' via the feed channel 13'. The cores of the hi-component fibres are preformed therein.

The sheath component enters the passage 3 axially and from there enters the guide channels 7' of the metallic foil 2' via feed channels 12' and passages 18'. It flows therein towards the spinning openings 10, surrounds the cores which are forming and is discharged from the spinning openings 10 together with the cores.

The spinning head shown in Figure 20 also comprises the housing 1, only one of the cylindrical passages of which is shown. The metallic foil 6 having spinning openings 10 lies against the wall of the passage 3. The housing 1 has groove-shaped recesses 5 in the area of the spinning openings 10. The metallic foil 2' having guide channels 7' lies closely against the metallic foil 6. A third metallic foil 8' having openings 9' lies on metallic foil 2' and is pressed by block 11'. Block 11' is hollow and forms the feed channel 16' for the core component which is pressed through the feed channel 17' (which may be groove-shaped) and through the openings 9' of the metallic foil 8' where the cores of the bi-component fibres are formed.

The sheath component is fed via a central feed channel 4 into passage 3 and from there reaches the metallic foil 2' in the direction of the spinning openings 10 via the feed channels 7'. The sheath component surrounds the cores issuing from the openings 9' there, and bi-component fibres having core-sheath structure are extruded from the spinning openings 10.

The metallic foils 6, 2' and 8' are shown individually in Figures 21 to 23.

By varying the shape and size of the openings and/or guide channels, the cross-sections of the fibres obtained may be varied.

By using more than three metallic foils and selecting a suitable system of openings and guide channels in these metallic foils, fibre cross-sections may be produced which have more than two defined component ranges. In this way, matrix-fibril systems may be spun.

Three or four spinning components may also be processed by arranging further feed channels in addition.

WHAT WE CLAIM IS: 1. A spinning head for synthetic fibres of thermoplastic polymers which comprises a housing having at least two cylindrical passages having diameters of less than 30 mm running parallel to the underside of the housing, each of the cylindrical passages forming a recess in the underside of the housing, and a metallic foil less than 0.5 mm thick being located in each cylindrical passage, the foil contacting the wall of the cylindrical passage and lining at least part of the curved surface of the cylindrical passage under initial tension and having spinning orifices in the region of the recess and aligned with the recess, and the housing defining a pathway for the supply of molten thermoplastic polymer to each of the cylindrical passages.

2. A head as claimed in claim 1 having a plurality of recesses formed by grooves in the underside of the housing, the grooves running transversely of the cylindrical passages and parallel to each pother.

3. A head as claimed in claim 1 or claim 2 having hollow cylinders having recesses arranged in each of the cylindrical passages, each cylinder containing a metallic foil lying in contact with and partially lining the internal wall of the cylinder.

4. A head as claimed in claims 1 to 3 having cylindrical passages having laterally opening channels for the passage of molten thermoplastic polymer and having enlargements at the ends, the passages being closed by seals pressed against the housing by means of a bolt showing a head in one of the enlargements and a nut screwed on the bolt and located in the opposite enlargement.

5. A head as claimed in claim 4 having a bolt which is provided with heating or cooling means.

6. A head as claimed in any of claims 1 to 5 having a housing which is in two parts, the metallic foil or the hollow cylinder containing the metallic foil being inserted in pockets in the two parts of the housing.

7. A head as claimed in any of claims 1 to 6 adapted to produce multi-component fibres from at least two spinning components, each cylindrical passage having at least one other metallic foil pressed against the first metallic foil and provided with guide channels and/or openings for the passage of the spinning components, a convexly curved block pressing

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the following manner: A first spinning component (I) supplied through the central feed channel 15' reaches the guide channel 7' of the metallic foil 2' via the feed channel 13' and flows towards the spinning opening 10. A second spinning component (II) supplied axially through passage 3 reaches the feed channel 7 via feed channel 12' and also flows towards the spinning opening 10 where it meets spinning component I and is extruded with the latter with the formation of fibres having a side-byside structure. Bi-component fibres having a core-sheath structure may by produced using the spinning head shown in Figure 16. Another metallic foil 6 having spinning openings 10 (eight in this case) rests outside in a cylindrical passage 3 of the housing 1 and the housing 1 has a grooveshaped recess 5 in the range of this metallic foil 6. The central metallic foil 2' having guide channels 7' lies between the outermost metallic foil 6 and an inner metallic foil 8' provided with openings 9' and 18'. Three superimposed metallic foils 6, 2' and 8' (shown individually in Figures 17 to 19) are pressed against the wall of the passage 3 by a block 11'. The core component is supplied to the feed pipe 14' via the feed channel 15' and reaches the opening 9' via the feed channel 13'. The cores of the hi-component fibres are preformed therein. The sheath component enters the passage 3 axially and from there enters the guide channels 7' of the metallic foil 2' via feed channels 12' and passages 18'. It flows therein towards the spinning openings 10, surrounds the cores which are forming and is discharged from the spinning openings 10 together with the cores. The spinning head shown in Figure 20 also comprises the housing 1, only one of the cylindrical passages of which is shown. The metallic foil 6 having spinning openings 10 lies against the wall of the passage 3. The housing 1 has groove-shaped recesses 5 in the area of the spinning openings 10. The metallic foil 2' having guide channels 7' lies closely against the metallic foil 6. A third metallic foil 8' having openings 9' lies on metallic foil 2' and is pressed by block 11'. Block 11' is hollow and forms the feed channel 16' for the core component which is pressed through the feed channel 17' (which may be groove-shaped) and through the openings 9' of the metallic foil 8' where the cores of the bi-component fibres are formed. The sheath component is fed via a central feed channel 4 into passage 3 and from there reaches the metallic foil 2' in the direction of the spinning openings 10 via the feed channels 7'. The sheath component surrounds the cores issuing from the openings 9' there, and bi-component fibres having core-sheath structure are extruded from the spinning openings 10. The metallic foils 6, 2' and 8' are shown individually in Figures 21 to 23. By varying the shape and size of the openings and/or guide channels, the cross-sections of the fibres obtained may be varied. By using more than three metallic foils and selecting a suitable system of openings and guide channels in these metallic foils, fibre cross-sections may be produced which have more than two defined component ranges. In this way, matrix-fibril systems may be spun. Three or four spinning components may also be processed by arranging further feed channels in addition. WHAT WE CLAIM IS:

1. A spinning head for synthetic fibres of thermoplastic polymers which comprises a housing having at least two cylindrical passages having diameters of less than 30 mm running parallel to the underside of the housing, each of the cylindrical passages forming a recess in the underside of the housing, and a metallic foil less than 0.5 mm thick being located in each cylindrical passage, the foil contacting the wall of the cylindrical passage and lining at least part of the curved surface of the cylindrical passage under initial tension and having spinning orifices in the region of the recess and aligned with the recess, and the housing defining a pathway for the supply of molten thermoplastic polymer to each of the cylindrical passages.

against the other metallic foil and having at least one feed channel for the spinning component or contponents.

8. A head as claimed in claim 7 leaving three superimposed metallic foils.

9. A spinning head as claimed in claim 1 substantially as herein described.

10. A spinning head as claimed in claim 1 substantially as herein described with reference to the accompanying drawings.