GB1594530A - Spray spinning nozzle system - Google Patents

Description

(54) SPRAY SPINNING NOZZLE SYSTEM (71) We, CELANESE COR PORATION, a corporation organized and existing under the laws of the State of Delaware, located at 1211 Avenue of the Americas, New York, New York, U.S.A., 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 generally to the production of filamentary material and more particularly to a novel spray spinning nozzle for spinning molten synthetic resinous material to form a nonwoven structure.

Various apparatus have been developed in the past to create an integrated system for forming a fibrous assembly, such as a nonwoven fabric or the like, directly from a molten synthetic resinous material.

Typically, such an apparatus may use an extruder in which a synthetic resinous polymeric material is plasticated under the influence of heat and pressure to form a quantity of molten material which can then be forced through a nozzle orifice as a continuous liquid filament. Each of a plurality of high velocity gaseous jets is directed along the freshly extruded filament at a shallow angle to create a drag force for attenuating the filament which is then carried along by the attenuating gaseous jets and deposited on a collection surface to form a nonwoven structure. Such a device in the past has been known as spray spinning apparatus because the filamentary material appears to be sprayed against the collection surface.

The attenuating gaseous jets contribute to filament cooling in addition to both attenuating and conveying the filament to the collection surface. Since the filament of polymeric material is still in a somewhat molten or tacky stage as it strikes the collection surface, some sticking together occurs at each point where filament contacts itself. Also, the filament may loop about and stick to itself.

One such spray spinning apparatus is shown in our U.S. Patent No. 3,849,040.

This patent shows a stream of filamentary material emanating from a nozzle. A pair of elongated attenuating gas jets, each with a rectangular cross section, are placed on either side of the nozzle. The gas jet outlets are both in the same plane perpendicular to the nozzle axis, are positioned forwardly of the nozzle orifice and the gas jets therefrom intersect at a point offset from the nozzle axis in the plane of the nozzle axis. The axial component of the drag forces produced on the filament by the gas jets attenuates the filament. The filament is collected on a rotating mandrel against which is biased an idler roller for packing the collected filament into a cylindrical web. One disadvantage of such apparatus relates to the difficulty in controlling the spray pattern. The filament seems to wander, causing an unduly broad and unfocused spray pattern. Great care must be taken to control the geometry of the gas jets to provide a proper distribution in the collected filament. In addition, the intersecting jets diverge from their point of intersection in the direction of the collecting mandrel and produce a relatively wide spray pattern. Since only two vertically aligned planar discharge orifices are used, the resulting attenuating jets tend to control only two degrees of freedom of the filament stream.

Other existing spray spinning nozzles include jets which converge toward a filament in such a manner that the jet axes define a hyperboloid having a waist without intersecting the filament. Such nozzles also induce a twisting motion on the filament which is not a useful and desirable effect.

Moreover, as with the planar jets in the nozzle discussed above, the jets diverge downstream of the hyperboloid waist producing a wide spray pattern.

The spray pattern of known nozzles is appreciably larger than the diameter of the collecting mandrel. Accordingly, portions of the filament within the spray pattern but above and below the mandrel will spray past the mandrel and perhaps be collected on the idler roller. This phenomenon is called overspraying. As the idler roller and the mandrel are rotatable, the oversprayed filament may be broken or irregularly compacted. These effects will cause difficulty in controlling the uniformity of the nonwoven structure.

Large spray patterns may also permit the filament to overcool so that it will be somewhat less molten and less tacky when it strikes the collection mandrel and, therefore, less apt to properly bond together so as to form an integrated nonwoven structure. Thus, large spray patterns produce products with poor filament bonding and inferior strength.

One disadvantage of the system shown in U.S. Patent No. 3,849,040 is that the angles of the gas jets require adjustment when the gas pressure or polymer flow rate is changed. Thus, careful and time-consuming control of the gas pressure and gas jet angles is required.

The molten polymer and the attenuating gas do not flow through the same nozzle.

The gas jets are separated from the nozzle orifice by an insulating means such as an air space. As a result, the gas jets produce a low pressure area near the nozzle orifice which induces a flow of ambient air past the nozzle. This induced flow tends to convectively cool the nozzle and to cause the molten material to harden. and obstruct the orifice: known as nozzle freeze-up.

In the past it has been necessary to use high throughput rates of polymeric material through the nozzle to reduce nozzle freezeup. This produces a thicker filament, requires higher gas supply pressure to obtain high momentum in the attenuating gas jets, and requires the distance between the nozzle orifice and the collection surface to be greater than desired. As a result of these higher operating parameters, the nonwoven structures produced by present spray spinning apparatus have not been entirely satisfactory. The filament is relatively thick and also includes quantities of "shot" which is solid debris or beads of non-attenuated material which increase cost and weight of a product and undesirably affect the feel of the nonwoven product.

Uniformity of filament thickness and spray pattern has been difficult to attain and maintain. Collection can be difficult and attenuation efficiency has been low. Under these conditions overall operation can be difficult.

There is a need for a nozzle attenuating system which can be continuously operated without freezing due either to conductive cooling caused by direct contact between the gas jet and the nozzle body or convective cooling caused by induced air flow when the gas jet is spaced apart from the nozzle body.

A nozzle which does not readily freeze-up will permit lower polymer throughput rates and improve the resulting filament and nonwoven product. It is also desirably to have a gas jet which can be easily disassembled from the nozzle body to reduce the time necessary to clean the nozzle should it become obstructed.

During start-up of a horizontal spray spinning system, the plasticated synthetic resinous material passes through the nozzle orifice and is allowed to drip without attenuation, when time-wise steady temperature and flow conditions are obtained, the gas jets are brought into operation to attenuate and convey the filament to the collection surface.

Also, during operation of the spray spinning apparatus, aberrant performance of a spray spinning nozzle may necessitate abrupt interruption of the action of the gas jets to avoid ruining a product being manufactured. Easy disassembly of the system is advantageous.

Another significant problem with spray spinning nozzles relates to the manner in which orifice blockage can be removed.

Generally, extensive disassembly of the nozzle is required. In fact, in many instances, the entire spray spinning nozzle must be removed from the source of polymeric material and disassembled. With a small diameter extrusion orifice, the likelihood of blockage and freeze-up is materially increased.

Accordingly, it will be apparent to those skilled in the art that there continues to exist a need for a spray spinning nozzle assembly which overcomes problems of the type discussed above.

A spray spinning nozzle in accordance with the invention includes a nozzle assembly for receiving synthetic resinous polymeric material from a source thereof.

The nozzle assembly includes -a fluid passage with an opening in the distal end communicating with the passage. The opening is adapted to receive an orifice body having an extrusion orifice therethrough.

In order to attenuate a filament of synthetic resinous material extruded through the orifice and to convey the attenuated filament to a collection surface, an assembly for directing gaseous jets in the general direction of the filament is provided. This assembly may include a manifold for receiving and distributing pressurized gas to a plurality of jet forming conduits.

The jet forming conduits can extend in cantilever fashion from the manifold to a position downstream of the extrusion orifice and eliminate an annular member around the orifice which might be fouled by synthetic resinous material during, for example, starting. Each jet forming conduit has a discharge opening positioned at a common radius from the axis of the extrusion orifice and discharges a gaseous jet at a common angle with respect to the axis. In this manner, the gaseous jets provide a balanced gaseous flow around the filament to provide good spray pattern control. Moreover, by locating the discharge openings downstream of the extrusion orifice, the likelihood of convective cooling and material freeze-up in the orifice is diminished since high velocity jets do not traverse the orifice body.

The manifold, with the cantilevered jet forming conduits, is adapted to be laterally movable relative to the nozzle assembly and the orifice body. In this fashion, the manifold and the gaseous jets can be moved into operative relationship with the filament when the polymeric material attains uniform conditions at start-up. Moreover, the manifold and the gaseous jets can be quickly moved out of operative relationship relative to the filament in the event there is a malfunction in the nozzle assembly, orifice body or an upstream supply device.

In order to adjust the direction of the filament being spray spun, the manifold is mounted for translation in each of three orthogonal directions as well as for rotation about each of two perpendicular axes, each of which is also perpendicular to the nozzle axis.

By arranging the jet forming conduits so that no conduit is positioned vertically below the extrusion orifice, the potential that any polymeric material can collect on any one of the conduits is severely diminished.

With the extrusion orifice positioned in a removable orifice body, the delay in eliminating a plugged orifice is also reduced. This reduction is effected by the ability to quickly remove and replace the orifice body without completely disassembling and reassembling the spray spinning nozzle.

To enable the spray spinning nozzle to operate at low polymeric material throughput rates, the jet forming conduits may include serpentine bends to position the discharge openings thereof radially close to the nozzle orifice axis as well as axially close to the nozzle orifice exit plane.

In this manner, the gaseous jets are positioned sufficiently close to the orifice to pick up a filament which emanates from the orifice at a comparatively low velocity associated with a low throughput rate.

The nozzle assembly is preferably provided with heating means to guard against heat loss by convective cooling and to maintain the nozzle assembly and orifice body at a suitable temperature. Preferably, the temperature is maintained at a level in the range between the melting temperature of the material being extruded into a filament and that temperature at which the material becomes so degraded as to be incapable of forming a substantially continuous filament. This temperature range resists any external influences which might otherwise tend to cause nozzle freezeup.

In one embodiment of the spray spinning nozzle, the nozzle assembly has a polymeric material passage which is straight and extends to the orifice body. The manifold has a C-shaped cross-sectional configuration which is adapted to move laterally with respect to the axis of the extrusion nozzle into a saddle-like relationship to the nozzle assembly. In this embodiment, the manifold configuration permits a straight material passage which reduces the likelihood of material degradation during traversal of the nozzle assembly.

The orifice body is preferably mounted in in opening at the distal end of the nozzle assembly so as to be essentially flush with the distal end thereby minimizing heat loss by convective cooling. Moreover, the end portion of the orifice body is radially spaced from the surrounding nozzle assembly and defines an annular recess which facilitates removal of the orifice body in the event of thermal expansion.

In a second embodiment of the spray spinning nozzle, the nozzle assembly includes an offset adapter having a polymeric material passage therethrough which radially displaces the orifice body from an inlet. The manifold may have an easily fabricated cylindrical configuration with the jet forming conduits extending therefrom. The jet forming conduits traverse the distal end of the offset adapter and are positioned around a filament emanating therefrom.

The angle formed between the axis of the nozzle body along which the filament is attenuated and the axis of the gas jet may be varied. In one embodiment, the gas jets impinge upon the filament at the same shallow angle converging to a point and then crossing over and diverging to the collection surface. The cross-over point can be varied to control the spray pattern impinging on the collection surface.

Alternatively the jets may be aligned parallel to the nozzle body axis. Since the gaseous jets are spaced about the axis, they form a balanced flow of attenuating gas about the filament. Since the jets are aligned essentially parallel to the axis the area of the resulting attenuating gas flow can be controlled by adjusting the radial distance at which the discharge orifices are placed from the axis. The jets do not intersect and then diverge from a point of intersection closer to the nozzle than to the downstream collection surface. Thus, the spray area of the filament is controlled to minimize undesirable overspray and the properties of the nonwoven structure can be belter controlled.

Essentially parallel flow of the gas jets has the further advantage of producing a filament of a greater and more uniform medium diameter to form a stronger and more uniform structure. In comparison to converging and diverging spray patterns, essentially parallel flow also produces a filament which includes less "shot" or solid debris in the form of non-attenuated polymeric material and thus produces a nonwoven structure having a better feel while conserving polymeric material.

In another embodiment the nozzle includes a narrow central portion connecting an enlarged tip portion and a mounting head for connecting the nozzle to an extruder. The enlarged tip portion includes recesses spaced about the peripheral surface thereof for partially accommodating conductive heating means.

It has been discovered that the fluid properties of the polymer melt will not be adversely affected by providing conduction heating in the area of the nozzle tip portion.

Consequently, the present invention provides heating means to maintain the nozzle tip. portion within a predetermined temperature range, to reduce the possibility of nozzle freeze-up. The enlarged tip portion is constructed of metal with a good thermal conductivity and has a sufficient mass of material to facilitate an even temperature distribution throughout the tip.

Spaced between the heater means recesses on the nozzle tip are a plurality of notches that facilitate the placing of gas jet exits of the attenuating system radially close to the nozzle orifice. The notches also provide a means for mounting the attenuating system on the nozzle. It is desirable to place the gas jets radially close to the nozzle centerline so that the angle at which the gas jet contacts the freshly extruded filament may be made small. This permits, amohg other things, the use of lower gas stream supply pressures. Also, because the present invention contemplates lower polymer nozzle throughput rates, it is desirable to have the gas stream contact the filament quickly at a position close to the nozzle orifice.

The gaseous jet attenuating assembly includes an annular manifold and a generally cylindrical gas jet housing which slides onto the nozzle. The manifold has an annular plenum chamber which communicates with a plurality of gas jet passages in the gas jet housing. The discharge openings. of the gas jet passages are disposed in a small circle about the nozzle axis. The gas jet passages may be aligned so that the individual attenuating gas jets converge at a small angle to the nozzle axis and intersect one another at a common point along the nozzle axis in front of the nozzle orifice.

The gas jet housing includes a central passage which has projections directed toward the nozzle axis. The projections mate with the complimentary notches on the nozzle tip portion. The gas jet discharge openings are in these projections to facilitate jet placement radially close to the nozzle axis. Clearance between the projections and the notches is sufficient to permit sliding of the manifold assembly onto the nozzle. There is not a sufficient space to permit an induced air flow to develop about the nozzle tip portion.

The gas jet housing also includes recesses between the projections which are complimentary to and align with the corresponding recesses on the nozzle tip portion so as to form pockets in which the heater means may fit. As the attenuating assembly slides over the nozzle, the rear surface of the gas manifold abuts spikes which project axially forward from the forward facing surface of the nozzle mounting head to provide a working space for the heater electrical connection.

When assembled, the nozzle orifice is preferably recessed behind the free end of the gas jet housing. The plane of the gas jet discharge openings is slightly forward of the exit plane of the nozzle orifice so as to reduce the risk of nozzle freeze-up from gaseous jet cooling.

Other features and advantages of this invention will become apparent from the following description of the preferred embodiments thereof taken in conjunction with the following drawings wherein: Figures 1 and I a are schematic illustrations of an integrated spray spinning assembly in which a spray spinning nozzle according to the invention may advantageously be employed with converging-diverging gas jets in the embodiment of Figure 1 and parallel gas jets in the embodiment of Figure la.

Figure 2 is an enlarged perspective view of one embodiment of the spray spinning nozzle and its associated attenuating assembly with portions broken away for the sake of clarity; Figure 3 is a longitudinal view in partial cross section of the nozzle and attenuating assembly shown in Figure 2; Figure 3a is a partial longitudinal view in partial cross section showing parallel gas jets; Figure 4 is a front elevational view of the nozzle and attenuating assembly shown in Figure 2; Figure 5 is an enlarged perspective view of a second embodiment of the spray spinning nozzle and its associated attenuating assembly; Figure 6 is a longitudinal view in partial cross section of the nozzle and attenuating assembly shown in Figure 5; Figure 6a is a partial longitudinal view in partial cross section showing parallel gas jets; Figure 7 is a front elevational view of the nozzle and attenuating assembly shown in Figure 5; Figure 8 is a partial cross-sectional view taken along the line 8-8 of Figure 6; Figure 9 is an enlarged view of an orifice body for producing several filaments; Figure 10 is a perspective view of another embodiment of the invention shown partially broken away for clarity; Figure 11 is a rear elevation view of the nozzle of Figure 10; Figure 12 is a partial cross-sectional view taken longitudinally of the embodiment of Figure 10; and, Figure 13 is a front elevational view of the embodiment of Figure 10.

In reference to Figure 1, a spray spinning system in accordance with the present invention includes a source of molten synthetic resinous polymeric material which may include a suitable conventional extruder 11 for plasticating particulate synthetic resinous material under appropriate conditions of heat and pressure.

The plasticated or melted material may then be advanced to a suitable conventional melt pump 13 where the material may be further pressurized and delivered to a horizontally oriented spray spinning nozzle assembly 15 constructed in accordance with this invention.

Also communicating with spray spinning nozzle assembly 15 is a suitable source 17 of pressurized gaseous fluid, such as pressurized ambient air. The spray spinning nozzle assembly 15 shapes the melted material into a filament 19 and directs a gaseous current of pressurized air jets toward the filament to attenuate the filament, cool the filament, orient the material of the filament and convey the filament to a suitable conventional collection surface 21. In Figure 1, the gas jets are shown converging an(t diverging. In Figure la all similar elements are similarly numbered and the gas jets are shown parallel to each other and to filament 19.

Turning now to Figure 2, the spray spinning nozzle includes an extrusion nozzle (generally identified as 1) from which a substantially continuous filament of.molten polymeric material is emitted. An assembly (generally designated as 2) is provided for emitting converging symmetrically aligned gas jets which contact the filament at a point 23 along an axis 25 of an orifice body 27.

The point 23 is also in front of the orifice body 27 so that the gas jets attenuate the molten polymeric filament to a thin diameter. The filament may then be carried along by the gas jets and onto the collection surface to form a three-dimensional nonwoven structure.

The nozzle assembly 1 has a generally cylindrical body 10 (see Figure 3) with a mounting head 12 connected to one end thereof for mounting the nozzle assembly to the melt pump or the extrusion apparatus.

The body 10 receives polymeric material from the extruder and advances the material to the orifice body 27. The nozzle assembly 1 may have a generally axial fluid passage 10a extending throughout its length which includes a generally cylindrical portion and, in the mounting head 12, a frustoconical portion. The frustoconical portion tapers convergently toward the nozzle centerline.

The nozzle centerline is coaxial with the axis 25 of the orifice body 27.

At the distal end of the body 10, there is a coaxial cylindrical recess or opening 14 for accommodating the orifice body 27. The orifice body 27 includes a body section 18 having a diameter greater than fluid passage 10a of the nozzle body 10. The discharge end of the orifice body 27 has a head 20 in which are disposed four axial sockets 22 that accommodate a spanner wrench. The spanner wrench may be used to tighten or remove the orifice body 27 from the nozzle body 10 without disassembling the entire nozzle assembly 1. The body section 18 is externally threaded and has a diameter sufficient to accommodate threads of a size and strength to hold the orifice body 27 securely inside the end of the body 10. The diameter of the recess 14 is correspondingly chosen to accept the body section 18 and is internally threaded.

The orifice body 27 has a central passage 10b which tapers in two steps to an extrusion orifice 24 having a diameter of approximately 0.016 inches and a length of approximately 0.064 inches. The discharge end of the extrusion orifice 24 may project slightly beyond the plane of the head 20. An annular coaxial flange 26 projects axially from the periphery of nozzle body 10 and completely surrounds the head 20. The outside diameter of the head 20 is less than the inside diameter of the flange 26 so that an annular air space 29 is provided between the head 20 and the flange 26. This annular air space 29 prevents binding between the head 20 and the flange 26 at high temperatures. The head 20 and the flange 26 terminate in the same plane and are essentially flush with one another.

The body 10 and the mounting head 12 are each completely surrounded by suitable conventional heating means 28, 30 which provide conductive heat transfer to the body 10 and the head 12 respectively. The heating means 28, 30 maintain the nozzle body 10 within a predetermined temperature range. This temperature range is preferably between the melting temperature of the particular polymeric material and that temperature at which the polymeric material becomes so degraded as to be incapable of forming a substantially continuous filament so that any tendency to freeze-up is substantially diminished.

The attenuating apparatus 2 includes a hollow manifold 40 having a C-shaped cross-sectional configuration (see Figure 4).

The manifold 40 is suspended about the nozzle body 10 in a saddle-like relationship by a device 42. Preferably, the device 42 is adapted for moving the manifold 40 axially with respect to the nozzle body 10, for moving the manifold 40 transversely of the axis 25 in a horizontal plane, and for moving the -manifold 40 traversely of the axis 25 in a vertical plane. In addition, the device 42 may rotate the manifold 40 about a vertical axis perpendicular to the nozzle axis 25 and may rotate the manifold 40 about a horizontal axis perpendicular to the nozzle axis 25. With the foregoing adjustability, the manifold 40 can be adjusted as required to direct the filament extruded through the orifice 27 and to accommodate maldistribution of the filament material issuing from the orifice body 27. A suitable means for laterally displacing the manifold 40 is connected to the device 42 to which the nozzle body 10 is connected so as to support the device 42.

The C-shaped cross section of manifold 40 allows it to be easily positioned laterally relative to the body 10; The manifold 40 defines a plenum chamber 44 (see Figure 3) into which pressurized attenuating gas (preferably ambient air) is directed through a coupling 46 from the supply apparatus 17 (see Figure 1). As seen in Figure 4, the inside surface 41 of the C-shaped manifold 40 is radially spaced apart from the peripheral surface of the body 10 and the heating means 28 therearound.

Extending in cantilever fashion from a forward facing surface 48 of the manifold 40 are three gas conduits 50 each of which communicate with the plenum chamber 44 (see Figure 3) to deliver a corresponding jet of attenuating gas to a location downstream of the extrusion orifice 24. The gas conduits 50 communicate with the plenum 44 through corresponding holes 52 in the forward facing surface 48. The inside of each hole 52 may be chamfered to facilitate air flow. Each gas conduit 50 may be fabricated from a reasonably stiff material such as stainless steel, which can be bent into a desired contour and will maintain that contour without external support. The discharge opening 53 of each gas conduit 50 is aligned in a plane perpendicular to the axis 25 of the orifice body 27. In addition, the discharge openings 53 are disposed at a common radius from the nozzle axis (see Figure 4) and may be equiangularly positioned. Each gas conduit 50 is directed (see Figure 3) to provide a gas jet which converges upon the nozzle axis 25 at an angle less than 45". Preferably the angle is in the range of 5 to 300. The gas jets intersect each other at the point 23 downstream of the extrusion orifice 24.

In Figure 3a there is shown a portion of the system shown in Figure 3 except that conduits 50 are aligned to provide parallel gas jets. In Figures 3 and 3a all similar elements are similarly numbered.

A minimum of three gas conduits 50 is required to provide a flow that is circumferentially balanced around the filament. Any number of gas conduits greater than three may be used so long as the gas conduit discharge openings 53 are coplanar and angularly spaced at a common radial distance from the axis 25. It will be observed from Figure 4 that no discharge opening 53 is positioned vertically under the extrusion orifice 24. In this manner, the molten filament is unlikely to fall upon and foul any of the discharge openings 53.

Because the present invention contemplates operating at a low material throughput rate, it is desirable to have the gas jets contact the molten filament quickly and close to extrusion orifice 24. This result is accomplished by positioning the discharge openings 53 of the gas conduits radially close to the axis 25 and axially close to the extrusion orifice 24. The serpentine or S-shaped configuration of the gas conduits 50 (see Figure 3) makes possible the appropriate positioning of the discharge openings 53.

The radius of the discharge openings from the axis 25 preferably is no smaller than about 0.25 inch and preferably is no greater than about 1.0 inch. Smaller radii would be likely to interfere with the filament as it leaves the orifice 24 as the filament does not always follow a straight path. Larger radii would be undesirable as the gas jets become too remote and their effectiveness diminishes requiring greater flow rates and higher gas pressures.

It will be observed from Figure 3 that an air space does exist between the body 10 and the inside surface 41 of the manifold 40.

The gas jets emanating from the discharge openings 53 will induce a certain amount of air flow through this space. This induced air flow, however, will not appreciably cool the body 10 because it is surrounded by the heater means 28. Furthermore, because the diameter of body 10 is reasonably large, most of this induced air flow will bypass the vicinity of the extrusion orifice 24 so that convective cooling will be minimized.

In operation (see Figure 3), a quantity of molten polymeric material enters the nozzle assembly I through the converging section of the nozzle passage 10a in the head 12 and proceeds to the orifice body 27 where it converges in two steps and is shaped by the extrusion orifice 24 into a filament.

Pressurized attenuating gas enters the intake 46, circulates in the plenum chamber 44, enters each gas conduit 50 through a corresponding chamfered hole 52 and exhausts from the corresponding discharge opening 53 as a plurality of substantially equiangularly spaced gas jets in front of the extrusion orifice 24. The jets intersect each other at the point 23 on the axis 25. As the filament generally follows the axis 25, the gas jets also impinge upon the freshly extruded filament. Alternatively as shown in Figures la and 3a the jets can be aligned parallel to the filament.

Drag forces exerted on the filament by the jets attenuate the freshly extruded filament to a fine diameter. The resulting filament is substantially continuous meaning that its length is measurable in feet. The filament is carried along by a combination of the gas jets and entrained air and then deposited on the collection surface to form a nonwoven structure.

During starting, as well as during operation, the manifold 40 can be moved laterally into and out of operative position with respect to the nozzle assembly 1.

Accordingly, the influence of gas jets on the filament can be interrupted as necessary.

Moreover, the positioning of the discharge openings 53 is such that the orifice body 27 is isolated from convective cooling effects.

The removable orifice body permits rapid return to operation as it can be rapidly changed in the event of orifice blockage.

Turning briefly to Figure 9, an orifice body 180 is disclosed which is similar to the orifice body discussed above in connection with the first embodiment. The orifice body 180 may be used in combination with the nozzle system of the first embodiment and includes three extrusion orifices 182 so that a plurality of filaments may be simultaneously emitted. The orifices 182 are preferably positioned at a common radius from the axis 184 and are preferably equiangularly spaced to achieve uniform fluid properties in the melt as it advances therethrough.

Turning now to Figure 5, there is shown a second embodiment of the present invention which includes an offset extrusion nozzle assembly (generally identified as 3) from which a continuous stream of molten polymeric material is emitted. An attenuation gas assembly (generally designated as 4) emits at least three symmetrically aligned converging gas jets which contact the filament at a point 80 along the axis 82 of an orifice body 84. The point 80 is downstream of the orifice body 84 to facilitate attenuation of the molten stream to a thin filament. The filament may be carried along by the gas jets in the same manner as described above in connection with the first embodiment.

The offset nozzle assembly 3 includes (see Figure 6) a generally cylindrical mounting head 100 for connecting the assembly to a source of molten polymeric material. A portion 102 of an L-shaped nozzle offset adapter 104 extends axially from a forward facing surface 103 of the mounting head 100. The nozzle offset adapter 104 includes a leg 105 extending generally perpendicularly from the distal end of the portion 102. The mounting head 100 has a rearwardly facing flange 86 (see Figure 6) for positioning the nozzle assembly 3 relative to the supply of extrudable material.

The nozzle assembly 3 (see Figure 5) may have a fluid passage 106 extending throughout its length and including generally cylindrical portions and, in the mounting head 100, a generally frustoconical portion 107. The frustoconical surface portion is positioned in the mounting head 100 and converges from the rearward facing flange 86 to the generally cylindrical fluid passage. The fluid passage 106 includes two bends 109, 111, each of which turns the polymeric material through an angle. The bends 109, 111 enable the axis 90 of a discharge opening 88 to be offset from the axis 92 of the adapter portion 102.

Thus, the offset fluid passage 106 in the offset adapter 104 permits a polymeric material stream to be extruded along the axis 90 which is parallel to but radially displaced from the axis 92 of the nozzle body portion 102.

An extrusion orifice 108 is disposed in the orifice body 84 which is mounted at the distal end of the offset adapter leg 105 and in the forward facing surface thereof. The orifice body 84 is removable and is aligned such that its axis 90 is coaxial with axis 90 of the opening 88 and parallel to the axis 92 of the portion 102.

The leg 105 of the nozzle offset adapter 104 has a trapezoidal cross section and includes a plurality of parallel cylindrical recesses 110, 112, 114 (see Figure 8) for accommodating a corresponding plurality of heater means 117. In Figure 6, two recesses 112, 114 extend from the radially remote surface 113 of adapter leg 105 toward the portion 102 and are generally parallel to and rearward of fluid passage 106. The recess 110 extends from the bottom surface 115 of the adapter leg 105 away from the axis 92 in a direction parallel to and forward of fluid passage 106. The recesses. 110, 112, 114 provide pockets surrounding the fluid passage 106 into which a corresponding plurality of heating means may be placed to provide conductive heat transfer to the leg 105. The heat transfer maintains the leg within the predetermined temperature range discussed above in connection with the first embodiment. The heater means may comprise a cylindrical cartridge heater 117 made of a material having a high electrical resistance which, when energized by an electrical circuit (not shown), generates heat and keeps the leg 105 within the temperature range discussed above. The adapter 104 is preferably made of material having good thermal conductivity and has sufficient mass to facilitate an even temperature distribution throughout the leg 105.

Confronting surfaces 118, 125 of the leg 105 and the head 100, respectively, each have a corresponding key 119, 121 on which the air attenuation assembly 4 can be mounted The attenuating assembly 4 includes a generally cylindrical hollow manifold 120 which includes generally rectangular keyways 122 and 124 on opposite end surfaces thereof for receiving the keys 119, 121 to mount the manifold 120 between the confronting surfaces 118, 125. The manifold 120 is aligned coaxially with the axis 90 of the orifice 108 and the orifice body 84. The axial length of the manifold 120 is slightly less than the distance between the confronting surfaces of adapter leg 105 and the head 100 so that the manifold 120 may slide laterally into position therebetween.

Suitable means may be connected to the air manifold 120 to move it laterally into and out of coaxial position with respect to the axis 90. Within the manifold 120 is a plenum chamber 126 into which a pressurized attenuating gas (preferably ambient air) is supplied through a coupling 128 from the supply thereof.

Extending from the forward facing surface 130 of the manifold 120 are three gas conduits 132 (see Figure 7), each of which communicates with the plenum chamber 126 (see Figure 6). Each conduit 132 provides a jet of attenuating gas in the vicinity of nozzle orifice 108. The gas conduits 132 are preferably made of a reasonably stiff material such as stainless steel. The discharge opening 134 of each conduit 132 is positioned in a plane perpendicular to the axis 90 (see Figure 6) of the nozzle orifice 108. In addition, the discharge openings 134 are preferably equiangularly disposed at a common radius from the axis 90 of the orifice 108. The conduits 132 are oriented to provide gas jets which converge upon the axis 90 of orifice 108 at an angle such as that described above in connection with the first embodiment. In addition, the gas jets intersect each other as well as the filament at the point 80. In Figure 6a, there is shown a portion of the system shown in Figure 6 except that the conduits 132 are aligned to provide parallel gas jets. In Figures 6 and 6a all similar elements are similarly numbered.

As with the first embodiment, a minimum of three gas tubes 132 are required to provide balanced flow. Any number greater than three conduits 132 may be used so long as the discharge openings are angularly spaced at a fixed radial distance from the orifice axis to provide a balanced flow.

The operation of the second embodiment is similar to that of the first embodiment. A quantity of molten polymeric material enters the nozzle assembly 3 through the converging section 107 of the nozzle passage in the head 100 and proceeds through the cylindrical portion 106 past the bends 109 and 111 to the nozzle body 84 where it is shaped by the extrusion orifice 108 into a substantially continuous filament.

Pressurized attenuating gas enters the intake 128, circulates in the plenum chamber 126, enters each of the gas conduits 135 as a plurality of equiangularly spaced gas jets in front of the extrusion orifice 108. The jets intersect each other at a point 80 on axis 90. As the filament generally follows the axis 90, the gas jets also impinge upon the freshly extruded filament. The filament is then attenuated and conveyed to a collection surface as described in connection with the first embodiment. Alternatively as shown in Figures la and 6a, the jets can be aligned parallel to the filament.

In another embodiment of the invention shown in Figure 10, the nozzle assembly has a generally cylindrical central portion 512 connecting an enlarged tip portion 514 and a mounting device 516 in fluid communicating relationship. The tip portion 514 has a generally star-shaped cross section. The mounting device includes a hexagonal mounting head 516 for attachment to a source of polymeric material. Three axially aligned spacer spikes 518 are supported at a fixed radial distance from a nozzle axis 523 or center line and are substantially equiangularly distributed on a forward facing surface 525 of the head 516.

The spikes 518 are operable to axially position the filament attenuating assembly 502 relative to the nozzle 501. A threaded connection 520 may extend from a rearward facing surface of the head 516 for connecting nozzle 501 to the polymer source.

The nozzle tip portion 514 terminates in a small extrusion orifice 522 which ultimately sizes the filament. The orifice 522 may have a diameter of about 0.016" and a length of about 0.064". The tip portion 514 has a peripheral surface 527 that includes three axially aligned concave arcuate recesses 524 (see Figure 13). The recesses 524 are substantially equiangularly spaced around the periphery of enlarged tip 514. Heating elements 526, such as generally cylindrical cartridge heater rods, are partially surrounded by the recesses 524 to provide conductive heat transfer to the tip portion 514. The heater elements 526 maintain tip portion 514 within a pre-determined temperature range by conductive heat transfer to minimize the possibility of nozzle freeze-up. The predetermined temperature range is preferably between the melting temperature of the particular polymeric material and that temperature at which the polymeric material becomes so degraded as to be incapable of forming a substantially continuous filament.

Between the plurality of'recesses 524 is a plurality of axially aligned spaced "V" shaped concave notches 529 that facilitate placement of gas jet discharge openings 531 of the attenuating assembly 502 radially close to the nozzle axis 523. If desired, concave notches 529 may be equiangularly spaced. In addition, the notches 529 provide a rotation limiting mounting on the nozzle 501 for attenuating assembly 502.

While the recesses 524 may be portions of a cylindrical surface, they are selected to conform to the external configuration of the corresponding heating elements 526 and need not be arcuate. In addition, the notches 529 need not be "V" shaped as any convenient shape will be satisfactory. The recesses 524 and the notches 529 also need not be axially aligned parallel' to the nozzle axis: the notches or the recesses or both may taper at convenient angles to permit even closer radial placement of gas jet exits to the nozzle orifice 522.

The nozzle 501 and especially the enlarged tip portion 514 are preferably made of a metal which has good thermal conductivity. The tip portion 514 is radially enlarged to provide a sufficient mass of material to facilitate even temperature distribution throughout tip 514.

The filament attenuating assembly 502 functions to direct jets of attenuating gas along the filament of freshly extruded molten polymer after the filament leaves the nozzle orifice 522. These jets of attenuating gas (preferably ambient air) produce a drag force on the filament to attenuate it into a relatively fine diameter preferably in the range of 0.0002" to 0.005". The drag force exerted on the extruded filament occasionally may cause the filament to break but the filament produced is substantially continuous in the sense that its length is on the order of feet. The attenuated filament is carried by the jets and deposited on a collection surface. Filament diameter will depend upon extrusion throughput rate, nozzle orifice dimensions and the operating gas pressure and the gas flow rate of the attenuation assembly.

The attenuating assembly 502 includes an annular manifold 530 and a generally cylindrical gaseous jet housing 540 (see Figure 12) which are held together in coaxially aligned abutting relationship by external threads 535 disposed on the outside of the housing 540 and mating internal threads 537 on the inside of a coaxial flange 532 which extends forwardly from an abutting surface 533 of manifold 530. The outside diameter of the annular manifold 530 is greater, and the inside diameter of the annular manifold 530 is less than the outside diameter of the housing 540. The manifold 530 includes a coaxially aligned annular slot extending from the abutting surface 533 partway through the manifold 530 to form an annular coaxial plenum chamber 534.

The chamber 534 receives attenuating gas delivered thereto through an intake connection 536 from the source of pressurized gas.

Three straight angularly spaced gas passages 542 extend through the length of the air jet housing 540. Each gas passage tapers at the same angle relative to the nozzle axis 523. One end of each passage 542 communicates with chamber 534; the other end of each passage 542 exhausts through a corresponding discharge opening 531 in the free end surface 539 of the housing 540 remote from manifold 530 and perpendicular to the nozzle axis 523. Each passage 542 provides a jet of attenuating gas emanating from air jet housing 540 and converging on the nozzle axis at a common point downstream of the extrusion orifice.

The discharge openings 531 of the passages 542 may be equiangularly spaced at a common radius from the nozzle axis 523.

Each passage 542 tapers at an angle less than 45" to the axis and preferably in the range of 10 to 300. A minimum of three passages 542 are required to provide spatial equilibrium of the fluid acting on the filament. Any number greater than three passages 542 may be used. Preferably, the passage exits are equiangularly spaced at a fixed radial distance from the centreline of housing 540 to provide a balanced fluid flow.

The inner peripheral surface or wall 541 (see Figure 12) of the air jet housing 540 defines an axially aligned central passage which permits the housing 540 to slide onto the nozzle tip 514. The inner peripheral surface 541 conforms to the surface 527 of the nozzle tip 514 (see Figure 13) and includes a plurality of complimentary recesses 548. The complimentary recesses 548 and the recesses 524 of the nozzle tip 514 are in radial alignment with one another and define pockets for the heating elements 526. Accordingly, the complimentary recesses 548 may be cylindrical in configuration where the heating element is cylindrical. While the recesses 548 may be axially aligned, they may also be inclined relative to the nozzle axis.

The confronting complimentary recesses 548 and recesses 524, which form the pockets for heater elements 526, minimize thermal gradients in the surface of the heater elements 526 which may cause damage to said heater elements.

In addition, the internal surface 541 defines spaced projections 546 which conform to and mate with complimentary "V" shaped notches 529 on nozzle-tip 514.

The clearance between the projections 546 and the notches 529 is sufficient to permit housing 540 to be easily inserted over and removed from the nozzle- tip in the axial direction and to permit sufficient thermal expansion of the tip 514 under the influence of heating rods 526 without binding. The projections 546, like the notches 529, need not be axially aligned but may taper to permit even closer placement of air jet discharge openings 531 to the nozzle orifice 522.

When the spray spinning nozzle is assembled, the attenuating assembly 502 fits coaxially over nozzle assembly 501 so that the extrusion orifice 522 is recessed behind the end surface 539 of air jet housing 540.

The proper recessed distance is maintained by the spikes 518 which project from the forward facing surface of the hexagonal mounting head 516 and abut against the confronting face of the manifold 530 (see Figure 12). Preferably, the spikes 518 space the head 516 apart from the manifold 530 a sufficient distance to permit a working space for heater and instrument wiring.

In operation, a molten polymeric material enters the nozzle 501 through threaded connector 520 and exits through the extrusion orifice 522 as a filament.

Attenuating gas enters the intake 536, circulates in the chamber 534, and passes out through the gas passages 542 in three jets. The jets exhaust from the housing 540 downstream of the orifice 522 and intersect each other at a point on--the nozzle axis 523.

Drag forces produced by the jets attenuate the freshly extruded filament to a fine diameter. The stream of fluid, including the jets and entrained ambient air carry the filament along and deposit it on a collection surface to form a nonwoven structure.

An electric current is passed through the heater rods 526 by a suitable conventional electric circuit (not shown). As the -rods 526 have a high electrical resistance, heat is generated and evenly distributed throughout the thermal mass of the enlarged nozzle tip 514 by heat conduction. The nozzle tip 514 is maintained af a relatively uniform temperature which generally corresponds to the melt temperature of the polymer being spun to minimize nozzle freeze-up. The heaters 526 may also have the effect of heating the gas manifold 540 and thus heating the gas jets as they pass through the passages 542.

The present invention provides a nozzle attenuation system that produces a substantially continuous polymer filament that can be collected into a satisfactory nonwoven structure.

It has been found that satisfactory nonwoven structures may be produced from various polymeric materials, for example, polypropylene, nylon, PET or polyacetal. It has been found that satisfactory conditions of producing polypropylene nonwoven structures include a melt temperature of 600"F to 7500F which produces a liquid melt having appropriate viscosity. A melt throughput of I to 10 lbs. per hour with a recessed nozzle is appropriate for an orifice diameter of 0.016 inch and an orifice length of 0.064 inch used in conjunction with the gas manifold. The gas manifold may have three gas passages which provide jets of air each directed at an angle of 15 to the nozzle axis and intersecting each other on the axis in front of the nozzle orifice. With ambient air supplied to the manifold at a pressure in the range of 10--100 p.s.i.g., satisfactory filament is produced.

Average filament diameters - obtainable with the nozzle attenuation system of the present invention are in the range of .0002" to .005" for polypropylene, nylon and PET.

Large fiber diameter is obtained from polyacetal.

Tests were conducted using nylon to compare the nonwoven structure obtained from the spray spinning apparatus disclosed in U.S. Patent 3,849,040 with the nonwoven structure obtained using the apparatus in the present invention. The results are shown in the following table: U.S. Patent Present Test Parameter 3,849,040 Invention Throughput in Ibs.

per hour 4.0 4.5 6.4 6.4 Air pressure (p.s.i.g.) 55 100 40 80.

Web Tensile strength (Ibs. per 3" of width) 6.0 4.6 6.0 12.9 Fiber size, average (mils) 3.3 3.6 1.9 0.73 It can be seen from the foregoing table that the tensile strength of the nonwoven structure produced by the apparatus of the present invention is as strong as or stronger than that produced by the patent invention.

Because the nozzle attenuating system of the present invention is well protected against nozzle freeze-up, it is possible to operate with a smaller polymeric material throughput rate and thus produce a finer filament. The nozzle assembly includes a removable orifice to facilitate quick replacement should it be necessary. The gas attenuation assembly moves laterally or axially - of the nozzle assembly to further facilitate quick access to an obstructed or malfunctioning nozzle orifice. Fast removal of the gas attenuation assembly permits filament collection to be quickly interrupted because, when the attenuation assembly is removed, the filament will tend to drop so as not to impinge the collection surface.

Furthermore, because the present apparatus is able to use smaller throughput rates and provide a thinner filament, the attenuation efficiency is higher and the pressure of the attenuating gas is correspondingly lower so that a- smaller amount of gas is used: This has a further benefit of permitting the collection surface to be placed close to the nozzle orifice.

Moreover, there is no need to adjust the angle of the attenuating gas stream to accommodate different gas pressures.

The spray spinning nozzle according to the present invention has the further advantage of providing a comparatively well focused spray pattern when compared to prior art devices. This pattern results from the enhanced directional control which the gas attenuation system provides for the filament.

In addition, the gas attenuation assembly produces a nonwoven product having superior strength in comparison to the prior art. The strength results from improved bonding of the filament with itself in the nonwoven product. This bonding improvement may result from less cooling of the filament during attenuation by virtue of the improved spray pattern definition.

It will be understood that the particular apparatus described in these preferred embodiments of the invention are susceptible to considerable modification without departing from the inventive concept herein disclosed. Consequently, it is not intended that the invention be limited to the precise details but only as set forth in the following claims.

WHAT WE CLAIM IS: 1. A spray spinning nozzle for producing a substantially continuous filament from molten synthetic resinous polymeric material comprising: nozzle means for receiving the material from a source of molten material, having a distal end with an- opening therein and a fluid passage therethrough; shaping means for forming a filament from the material, connected at the opening in fluid communication with the fluid passage and having an axis and an extrusion orifice; and, attenuation means for supplying gaseous jets angularly spaced about the axis, and including; at least three conduits, each having an exhaust opening, being aligned so as to create a drag force on said filament, and the exhaust openings being angularly spaced about the axis downstream of the extrusion orifice; and manifold means for supplying pressurized gas to the said conduits, having the said conduits connected thereto and extending so that the exhaust openings are downstream of the shaping means, and

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

Claims (24)

**WARNING** start of CLMS field may overlap end of DESC **. nozzle axis and intersecting each other on the axis in front of the nozzle orifice. With ambient air supplied to the manifold at a pressure in the range of 10--100 p.s.i.g., satisfactory filament is produced. Average filament diameters - obtainable with the nozzle attenuation system of the present invention are in the range of .0002" to .005" for polypropylene, nylon and PET. Large fiber diameter is obtained from polyacetal. Tests were conducted using nylon to compare the nonwoven structure obtained from the spray spinning apparatus disclosed in U.S. Patent 3,849,040 with the nonwoven structure obtained using the apparatus in the present invention. The results are shown in the following table: U.S. Patent Present Test Parameter 3,849,040 Invention Throughput in Ibs. per hour 4.0 4.5 6.4 6.4 Air pressure (p.s.i.g.) 55 100 40 80. Web Tensile strength (Ibs. per 3" of width) 6.0 4.6 6.0 12.9 Fiber size, average (mils) 3.3 3.6 1.9 0.73 It can be seen from the foregoing table that the tensile strength of the nonwoven structure produced by the apparatus of the present invention is as strong as or stronger than that produced by the patent invention. Because the nozzle attenuating system of the present invention is well protected against nozzle freeze-up, it is possible to operate with a smaller polymeric material throughput rate and thus produce a finer filament. The nozzle assembly includes a removable orifice to facilitate quick replacement should it be necessary. The gas attenuation assembly moves laterally or axially - of the nozzle assembly to further facilitate quick access to an obstructed or malfunctioning nozzle orifice. Fast removal of the gas attenuation assembly permits filament collection to be quickly interrupted because, when the attenuation assembly is removed, the filament will tend to drop so as not to impinge the collection surface. Furthermore, because the present apparatus is able to use smaller throughput rates and provide a thinner filament, the attenuation efficiency is higher and the pressure of the attenuating gas is correspondingly lower so that a- smaller amount of gas is used: This has a further benefit of permitting the collection surface to be placed close to the nozzle orifice. Moreover, there is no need to adjust the angle of the attenuating gas stream to accommodate different gas pressures. The spray spinning nozzle according to the present invention has the further advantage of providing a comparatively well focused spray pattern when compared to prior art devices. This pattern results from the enhanced directional control which the gas attenuation system provides for the filament. In addition, the gas attenuation assembly produces a nonwoven product having superior strength in comparison to the prior art. The strength results from improved bonding of the filament with itself in the nonwoven product. This bonding improvement may result from less cooling of the filament during attenuation by virtue of the improved spray pattern definition. It will be understood that the particular apparatus described in these preferred embodiments of the invention are susceptible to considerable modification without departing from the inventive concept herein disclosed. Consequently, it is not intended that the invention be limited to the precise details but only as set forth in the following claims. WHAT WE CLAIM IS:

1. A spray spinning nozzle for producing a substantially continuous filament from molten synthetic resinous polymeric material comprising: nozzle means for receiving the material from a source of molten material, having a distal end with an- opening therein and a fluid passage therethrough; shaping means for forming a filament from the material, connected at the opening in fluid communication with the fluid passage and having an axis and an extrusion orifice; and, attenuation means for supplying gaseous jets angularly spaced about the axis, and including; at least three conduits, each having an exhaust opening, being aligned so as to create a drag force on said filament, and the exhaust openings being angularly spaced about the axis downstream of the extrusion orifice; and manifold means for supplying pressurized gas to the said conduits, having the said conduits connected thereto and extending so that the exhaust openings are downstream of the shaping means, and

being movable into and out of operative position with respect to the shaping means.

2. The spray spinning nozzle of Claim 1 wherein the manifold means is laterally movable with respect to the shaping means.

3. The spray spinning nozzle of Claim 2 wherein each conduit has an S-shaped configuration so that the exhaust openings can be axially adjacent the shaping means.

4. The spray spinning nozzle of Claim 3 wherein: the nozzle means has a longitudinal axis coaxial with the axis of the shaping means; and, the manifold has a C-shaped configuration adapted to move into a saddle-like relation with the nozzle means so that the exhaust openings are spaced at a uniform distance from the shaping means.

5. The spray spinning nozzle of Claim 4 wherein: the opening of the nozzle means is positioned in a cylindrical recess at the distal end thereof; and, the shaping means includes a cylindrical end portion having a diameter less than the diameter of the cylindrical recess so as to define a circumscribing annular recess which reduces heat transfer therefrom.

6. The spray spinning nozzle of Claim 2 wherein the nozzle means includes an angled adapter having the opening at the distal end thereof to offset the shaping means from an inlet to the fluid passage.

7. The spray spinning nozzle of Claim 6, wherein: the manifold means includes a generally cylindrical chamber positioned on one side of the adapter distal end; and, the conduits extend transversely around the distal end to position the discharge openings downstream of the opening, the conduits being spaced to receive the distal end therebetween.

8. The spray spinning nozzle of Claim 7, wherein: the adapter includes a key on the distal end adjacent the manifold means; and, the manifold means include a slot adjacent the key, adapted to receive the key and cooperating therewith to rotationally position the manifold means.

9. The spray spinning nozzle of Claim 2, wherein the shaping means includes a plurality of orifices equidistant from the axis and equiangularly spaced therearound so that a corresponding plurality of filaments can be simultaneously produced.

10. The spray spinning nozzle of Ciaim 2, wherein the shaping means is removably connected to the nozzle means so that only the shaping means need be replaced if the extrusion orifice becomes blocked.

11. The spray spinning apparatus of Claim 1, wherein said conduits are aligned to provide essentially parallel gaseous jets.

12. The spray spinning nozzle ot Claim I wherein: said nozzle means has an axis, a first end, a second end and a peripheral surface; wherein said shaping means includes mounting means at the second end for connecting the nozzle means in fluid communication with a source of the material, and a plurality of circumferentially spaced recesses in the peripheral surface, each being generally parallel to the axis; and wherein said attenuation means includes an annular manifold defining a plenum, and a jet housing extending forwardly from the manifold and having an inner peripheral wall conforming to the peripheral surface and having a plurality of complimentary longitudinal recesses correspondingly positioned with the plurality of circumferentially spaced recesses and cooperating therewith to define a plurality of pockets, a plurality of spaced jet passages communicating with the plenum and aligned to converge on the axis downstream of the extrusion orifice; and further including heating means positioned in the plurality of pockets for supplying heat to the nozzle means.

13. The spray spinning nozzle of Claim 12, wherein the peripheral surface includes a plurality of notches, each notch positioned between two of the plurality of recesses, and each of the plurality of jet passages having a discharge opening in a corresponding notch so as to reduce the diameter of a circle connecting the jet passage discharge openings.

14. The spray spinning nozzle of Claim 12, wherein the said plurality of recesses and said plurality of complimentary longitudinal recesses define a plurality of cylindrical pockets.

15. The spray spinning nozzle of Claim 12 wherein said notches define a generally "V" shaped surface cooperating with said conforming inner peripheral wall to rotationally position said attenuating means.

16. The spray spinning nozzle of Claim 12, further including means for spacing said manifold axially apart from said mounting means to provide a working space therebetween.

17. The spray spinning nozzle of Claim 12, wherein said heating means includes generally cylindrical heater rods aligned parallel to the axis of said nozzle means to provide conductive heat transfer to said nozzle means and said jet housing; and wherein said nozzle means is fashioned from a sufficient quantity of thermally conductive material to provide a temperature distribution which retards nozzle freeze-up.

18. The spray spinning nozzle of claim 12, wherein each jet passage has a discharge opening and wherein said nozzle orifice is recessed from a plane defined by the jet passage discharge opening by a predetermined distance to provide a heated recess in the vicinity of the nozzle means.

19. The spray spinning nozzle of any one of claims 2 to 10, in which the exhaust openings of the conduits are arranged so as to direct the gaseous jets that they converge on the axis at the same point.

20. The spray spinning nozzle of any one of claims 12 to 18 in which the extrusion orifice is positioned at said first end and coaxially with respect to the axis, the gaseous jets are so oriented to converge on the axis at the same point, and the attenuating means is coaxial with the axis.

21. The spray spinning nozzle of claim 2 in which the exhaust openings of the conduits are arranged so to direct the gaseous jets that they are substantially parallel.

22. A spray spinning nozzle substantially as hereinbefore described and as illustrated in Figures 1, 2, 3 and 4 or as illustrated in Figures 5, 6, 7 and 8.

23. A spray spinning nozzle substantially as hereinbefore described and as illustrated in Figures 10 to 13.

24. A spray spinning nozzle substantially as hereinbefore described and as illustrated in Figures la and 3a or as illustrated in Figure 6a.