Abstract:
A linear flow equalizer for distributing thermoplastic material to a spin pack of a meltspinning apparatus that provides for uniform apportionment of a flow of a flowable thermoplastic material at least vertically and in a cross-machine direction of the spin pack. The linear flow equalizer includes an inlet plate with multiple liquid passageways equidistantly spaced in the cross-machine direction that each provide flowable thermoplastic material to a set of equalizer plates. Elongated slots extending through alternating equalizer plates are registered with throughholes extending through adjacent plates in the equalizer plate set. Each throughhole in an upstream equalizer plate is registered with the center of a corresponding slot and each throughole in a downstream equalizer plate is registered with one of opposed closed ends of a corresponding slot.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to melt-spinning apparatus and methods, and more particularly to a linear flow equalizer for a spin pack of a melt-spinning apparatus and methods of forming non-woven webs with a melt-spinning apparatus incorporating the linear flow equalizer of the invention.  
       BACKGROUND OF THE INVENTION  
       [0002]     Non-woven webs are incorporated into a diversity of consumer and industrial products, including disposable hygienic articles, throwaway protective apparel, fluid filtration media, and household durables. Generally, non-woven webs are formed using melt-spinning technologies, such as spunbonding processes and meltblowing processes, that form continuous filaments or fibers composed of one or more thermoplastic polymers. Spunbond non-woven webs are relatively strong in both the machine and the cross-machine directions because of drawing that aligns the polymer molecules. The continuity of the filaments also contributes to the observed strength of spunbond non-woven webs. Spunbond non-woven webs also resist abrasion, have a high porosity, and may be soft and conformable.  
         [0003]     Spunbonding processes generally involve pumping one or more molten thermoplastic polymers through a spin pack that distributes, filters, combines, and finally extrudes continuous filaments of the constituent thermoplastic polymer(s) through hundreds or thousands of spinneret holes or orifices in a spinneret. After extrusion, the filaments are cooled or quenched to increase their viscosity and then drawn or stretched by an impinging high-velocity airflow generally capable of orienting the molecules of each constituent thermoplastic polymer if the air velocity is sufficiently high. The airflow propels the drawn filaments toward a forming zone to form a non-woven web on a moving collector.  
         [0004]     The spin pack distributes a flow of each constituent thermoplastic polymer from a few inlet ports to individual outlet ports that span the width of the spin pack. Specifically, the molten thermoplastic polymer from each inlet port is directed into a shared lateral flow passageway and individual portions of the incoming thermoplastic polymer are allocated from the lateral flow passageway to the outlet ports for subsequent distribution to the orifices in the spinneret plate. Because all of the inlet ports share a single lateral flow passageway, thermoplastic material streaming from adjacent inlet ports into the lateral flow passageway intersects, collides and mixes before arriving at the outlet ports. The intersecting streams of molten thermoplastic polymer may experience hold-ups, dead spots or stagnation zones, and/or recirculation within the lateral flow passageway. The individual streams of the polymer(s) from the outlet ports are ultimately supplied to the orifices in the spinneret.  
         [0005]     The inability to uniformly divide the incoming stream of the molten thermoplastic polymer in the machine direction and in the cross-machine direction with uniform flow characteristics to the outlet ports causes unacceptable variations in the non-woven web formed by the spunbonding process. For example, non-uniform distribution of the molten thermoplastic polymer in cross-machine direction may cause the basis weight of the non-woven web to fluctuate in the cross-machine direction, which produces perceptible strips of varying basis weight extending parallel to the machine direction. In particular, the basis weight of the non-woven web originating from filaments extruded from spinneret orifices receiving thermoplastic polymer from outlet ports directly downstream of an inlet port has been observed to be significantly larger than the basis weight of the non-woven web originating from filaments extruded from spinneret orifices receiving thermoplastic polymer from outlet ports near the mid-point between adjacent inlet ports. The fluctuation in the basis weight is believed to arise from unequal flow path lengths in the shared lateral flow passageway. This results in non-uniform residence times and pressure drops for different portions of the non-Newtonian thermoplastic polymer exiting the outlet ports from the lateral flow passageway. The non-uniform flow path lengths also result in disparate shear histories for different portions of the thermoplastic polymer flowing in the lateral flow passageway reflected in the polymer properties and the characteristics of the non-woven web formed therefrom.  
         [0006]     It would be desirable, therefore, to provide a spin pack for a melt-spinning apparatus capable of forming a non-woven web having improved basis weight uniformity in the cross-machine direction.  
       SUMMARY  
       [0007]     In one aspect, the invention is directed to an apparatus for distributing thermoplastic material supplied to a spin pack of a meltspinning apparatus. The apparatus includes a linear flow equalizer having a plurality of flow passageways of substantially equal length that divide a flow of a thermoplastic material supplied from a plurality of liquid inlet ports into individual streams having a spaced relationship in a cross-machine direction.  
         [0008]     In one specific embodiment of the apparatus of the invention, the linear flow equalizer includes an inlet plate having a plurality of liquid passageways spaced substantially equidistantly in a cross-machine direction of the meltspinning apparatus, a first equalizer plate positioned downstream from the inlet plate, and a second equalizer plate positioned downstream from the first equalizer plate. The first equalizer plate has elongated slots each centered about one of the plurality of liquid passageways. Each of the first plurality of elongate slots extends in the cross-machine direction and includes opposed closed ends substantially equidistant from one of the plurality of liquid passageways. The second equalizer plate has throughholes each substantially registered in alignment with one of the opposed closed ends of a corresponding one of the first plurality of elongated slots.  
         [0009]     Another aspect of the invention is directed to a method of distributing thermoplastic material supplied to a spin pack to form a non-woven web. To that end, a flow of thermoplastic material is divided in a cross-machine direction of a spin pack among liquid passageways of substantially equal path length to form individual streams of thermoplastic material spaced in the cross-machine direction. The individual streams of thermoplastic material are shaped or formed into filaments, which are quenched, drawn, and collected to produce the non-woven web.  
         [0010]     In accordance with the principles of the invention, the flows of thermoplastic material within the linear flow equalizer are partitioned homogeneously and symmetrically in the cross-machine direction and vertically in a downstream direction. The basis weight of the non-woven web produced by a melt spinning apparatus incorporating the linear flow equalizer of the invention is more uniform in the cross-machine direction. The improved uniformity in the basis weight is believed to arise from equal or nearly equal flow path lengths in the spin pack, which results in more uniform residence times and pressure drops for different divided portions of the thermoplastic polymer and approximately equal shear histories. As a result, the properties of the non-woven web are substantially independent of the lateral location of the outlet port from the final downstream equalizer plate relative to the individual inlets in the inlet plate. In accordance with the principles of the invention, the linear flow equalizer of the invention optimizes the flow distribution of the thermoplastic polymer(s) while achieving a uniform shear rate and a minimum residence time in the die pack.  
         [0011]     These and other objects and advantages of the present invention shall become more apparent from the accompanying drawings and description thereof. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0012]     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention.  
         [0013]      FIG. 1  is a perspective view of a spin beam assembly;  
         [0014]      FIG. 2  is a partial cross-sectional view taken generally along lines  2 - 2  in  FIG. 1 ;  
         [0015]      FIG. 3  is an exploded view of a linear flow equalizer for a spin pack in accordance with the principles of the invention;  
         [0016]      FIG. 4  is a bottom view of the inlet plate of the spin pack of  FIG. 3 ;  
         [0017]      FIG. 5  is a cross-sectional view taken generally along lines  5 - 5  in  FIG. 4 ;  
         [0018]      FIG. 5A  is a cross-sectional view similar to  FIG. 5  in accordance with an alternative embodiment of the invention; and  
         [0019]      FIG. 6  is a diagrammatic view of the flow paths for molten thermoplastic polymer in the linear flow equalizer of  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]     With reference to  FIGS. 1 and 2 , a spin beam assembly, generally indicated by reference numeral  10 , for forming filaments includes a chassis  12  holding drive pumps  14 ,  15 ,  16 ,  17  each driven by a corresponding one of a set of motors  18 ,  19 ,  20 ,  21 . The motors  18 - 21  are suspended from the chassis  12  by an open framework of beams  22  and generally overlie the drive pumps  14 - 17 . Extending from each of the motors  18 - 21  is a drive shaft  18   a    19   a,    20   a,    21   a  that supplies a drive coupling with a corresponding one of the drive pumps  14 - 17 . The spin beam assembly  10  is incorporated into a melt-spinning apparatus that includes conventional components, such as a filament-drawing device for attenuating the filaments and a moving collector located on a forming table, for forming a non-woven web.  
         [0021]     Drive pumps  14  and  16  receive a flow of a first polymer (Polymer A) furnished by a supply line  23  from an extruder (not shown) and drive pumps  15  and  17  receive a flow of a second polymer (Polymer B) furnished by a separate supply line  24  from another extruder (not shown). The invention contemplates that the drive pumps  14 - 17  may be supplied by a single supply line communicating with and service by a single extruder. The first and second polymers may differ in composition, such as polyethylene and polypropylene, or may constitute two polymers of identical composition that differ with respect to a property such as melt flow rate or the presence or absence of an additive. The two polymers are heated to a temperature sufficient to produce a liquid or semi-solid material having a viscosity suitable for flow through an arbitrary set of passageways.  
         [0022]     With continued reference to  FIGS. 1 and 2 , a pump plate  26  attached to the chassis  12  supports the pumps  14 - 17 . Extending through the pump plate  26  is a plurality of liquid passageways  28 , of which two liquid passageways  28  are shown in  FIG. 2 , arranged in rows such that each is coupled in fluid communication with an outlet of one of the drive pumps  14 ,  16 . Also extending through the pump plate  26  is a plurality of liquid passageways  30 , of which one liquid passageway  30  is shown in  FIG. 2 , each coupled in fluid communication with an outlet of one of the drive pumps  15 ,  17 . Accordingly, each pump  14 ,  16  outputs a stream of polymer A to the liquid passageways  28  and each pump  15 ,  17  outputs a stream of polymer B to the liquid passageways  30 .  
         [0023]     The spin beam assembly  10  further includes a spin pack, generally indicated by reference numeral  32 , supported by support brackets  34 ,  36  within a housing  38  of chassis  12 . The spin pack  32  receives separate flows of the two polymers from the liquid passageways  28 ,  30  in pump plate  26 . The spin pack  32  is an assembly that incorporates, in order from a top or upstream side to a bottom or downstream side, a linear flow equalizer  40 , a combining plate  42 , and a spinneret plate  44 . A major or long axis of the spin pack  32  is aligned generally parallel to a cross-machine direction  45  ( FIG. 1 ), which is generally orthogonal to a machine direction  46 . A collector (not shown) collects the filaments discharged from the spinneret plate  44  of spin pack  32 .  
         [0024]     With reference to  FIGS. 2 and 3 , the linear flow equalizer  40  is an assembly constituted by an inlet plate  48  and three equalizer plate sets  50   a - c.  The inlet plate  48  includes inlet ports or passageways  52 , visible in  FIG. 3 , arranged in three spaced linear rows to coincide with the locations of liquid passageways  28 ,  30 . Adjacent inlet passageways  52  in each of the rows are spaced at equal centerline-to-centerline intervals, or a uniform pitch, across the width of the inlet plate  48 . In one specific embodiment of the invention, the inlet plate  48  features three rows of eight inlet passageways  52 .  
         [0025]     Inlet passageways  52  in the center row are registered for fluid communication at an upstream surface  54  of inlet plate  48  with the liquid passageways  30  in the pump plate  26 . Similarly, inlet passageways  52  in the two rows flanking the center row are registered in fluid communication at the upstream surface  54  of inlet plate  48  with the liquid passageways  28  in the pump plate  26 . Accordingly, each inlet passageway  52  in the center row receives an output stream of polymer B from one of pumps  15 ,  17  and each inlet passageway  52  in the rows flanking the center row receives an output stream of polymer A from one of pumps  14 ,  16 . The rows of inlet passageways  52  in inlet plate  48  adjacent the front and rear edges of the spin pack  32  distribute respective output streams of Polymer A to the equalizer plate sets  50   a,    50   c.  The central row of inlet passageways  52  distributes an output stream of Polymer B to the center equalizer plate set  50   b.    
         [0026]     In accordance with the principles of the invention, the fluid pathways in the linear flow equalizer  40  define approximately equal length lateral and vertical flow paths and, preferably, equal length flow paths, for each polymer stream in a flow path extending from the downstream side of the pump plate  26  to the downstream side of each of the equalizer plate sets  50   a - c.  The approximately equal lengths of the lateral and vertical flow paths in the linear flow equalizer  40  result in approximately uniform residence times and shear histories characterizing the polymer flows through the linear flow equalizer  40 . Preferably, the lateral and vertical flow paths for the polymers in the linear flow equalizer  40  are equal in length for providing optimum filament properties. Consequently, material properties of the resultant non-woven, such as basis weight, possess an improved uniformity in the cross-machine direction  45 .  
         [0027]     With reference to  FIGS. 3-5 , the inlet plate  48  includes shallow rectangular recesses or cavities  56 ,  57 ,  58  partitioned from one another by dividing walls  59 ,  60 . Each of the cavities  56 ,  57 ,  58  is dimensioned to receive one of the equalizer plate sets  50   a - c.  A downstream surface of each cavity  56 ,  57 ,  58  includes a series of shallow multi-segment channels  62  each centered about an outlet of one of the inlet passageways  52 . The channels  62  define a second stage or level of lateral and vertical thermoplastic material distribution in the linear flow equalizer  40 .  
         [0028]     Each channel  62  includes a linear segment  64  extending in the cross-machine direction  45  and centered or symmetrical about inlet passageway  52 . Linear segment  64  terminates at each opposed open end in fluid communication with the center of a corresponding one of a pair of linear segments  66  each extending in the machine direction  46 . The linear segments  66  are equidistant in the cross-machine direction  45  from the corresponding inlet passageway  52 . Each of the linear segments  66  is centered or symmetrical about the intersection with linear segment  64  and terminates at each open end in fluid communication with a slotted linear segment  68 . Each slotted linear segment  68  extends in the cross-machine direction  45  and includes a pair of opposed curved terminal or closed ends  69 ,  70 . Each slotted linear segment  68  is centered or symmetrical about the intersection with the corresponding one of the linear segments  66 . Therefore, the flow path length for the flowable thermoplastic material in each channel  62  is substantially equal and, preferably equal, from the inlet passageway  52  to the closed ends  69 ,  70  of each slotted linear segment  68 .  
         [0029]     As each of the equalizer plate sets  50   a - c  have identical constructions, only one equalizer plate set  50   a  is shown in  FIG. 3  and is described herein. Equalizer plate set  50   a  includes a plurality of, for example, five equalizer plates  72 ,  74 ,  76 ,  78  and  80 , a sheet-forming plate  82 , removable mesh filters  83 ,  84 , and  85 , a filter support plate  86 , and a seal  87  arranged in juxtaposition from the top or upstream side to the bottom or downstream side. The filter support plate  86  has a peripheral rim  88  surrounding a generally rectangular recess that captures the filters  83 ,  84 ,  85  in the set assembly. The equalizer plates  72 ,  74 ,  76 ,  78  and  80  are secured together and fastened to the inlet plate  48  by conventional fasteners  90  extending from countersunk openings in the inlet plate  48  through appropriately aligned bolt holes formed in each of the equalizer plates  72 ,  74 ,  76 ,  78  and  80  and secured by nuts  91  situated in countersunk openings on the downstream side of the sheet-forming plate  82 .  
         [0030]     Each of the equalizer plates  72 ,  74 ,  76 ,  78  and  80  is formed by milling or drilling a thin rectangular sheet of a suitable material using computer numerically controlled (CNC) machining. For example, equalizer plates  72 ,  74 ,  76 ,  78  and  80  may be formed by CNC machining from sheets of a metal alloy, such as 17-4 stainless steel, having thermal expansion characteristics compatible with the surrounding metal environment of the spin pack  32 . The equalizer plats  72 ,  74 ,  76 ,  78  and  80  may also be fabricated by alternative manufacturing techniques, such as by laser or chemical machining or by stamping.  
         [0031]     With reference to  FIG. 3 , equalizer plate  72  is positioned downstream of the inlet plate  48  and includes a plurality of flow passageways in the form of circular bores or thoughholes  92  extending vertically through the thickness of plate  72  from an upstream inlet to a downstream outlet. Contact between the equalizer plate  72  and the inlet plate  48  closes the channels  62  to define flow paths in equalizer plate  72  to the throughholes  92 . The throughholes  92  are arranged in two spaced linear rows such that each throughhole  92  is registered on an upstream surface  93  of plate  72  in substantial vertical alignment with one of the closed ends  69 ,  70  of one of the slotted linear segments  68  in equalizer plate  72 . Adjacent throughholes  92  in each of the rows are spaced at equal centerline-to-centerline intervals, or a uniform pitch, across the width of the equalizer plate  72 . The throughholes  92  receive flowable thermoplastic material from the channels  62  in inlet plate  48  and define individual liquid inlets supplying flowable thermoplastic material to equalizer plate  74 . The channels  62  and the throughholes  92  collectively define a second stage or level of lateral and vertical thermoplastic material distribution in the linear flow equalizer  40 .  
         [0032]     Equalizer plate  74  is positioned downstream of equalizer plate  72  and includes a plurality of slotted flow passageways  94  extending vertically through the thickness of plate  74  from an upstream inlet to a downstream outlet. A major axis of each slotted flow passageway  94  is aligned generally in the cross-machine direction  45 . The center of each slotted flow passageway  94  is registered on an upstream surface  99  of equalizer plate  74  in substantial vertical alignment with one of the throughholes  92  in equalizer plate  72 . Throughholes  92  and channels  62  cooperate to also divide the flow of thermoplastic material into two separate laterally-extending rows. As a result, opposed curved terminal or closed ends  96 ,  98  of each slotted flow passageway  94  are substantially centered or symmetrical in the cross-machine direction  45  relative to the corresponding throughhole  92 .  
         [0033]     With continued reference to  FIG. 3 , equalizer plate  76  is positioned downstream of equalizer plate  74  and includes a plurality of flow passageways in the form of circular bores or thoughholes  100  extending vertically through the thickness of plate  76  from an upstream inlet to a downstream outlet. Each throughhole  100  is registered on an upstream surface  101  of equalizer plate  76  in substantial vertical alignment with one of the closed ends  96 ,  98  of one of the slotted flow passageways  94  in equalizer plate  74 . Adjacent throughholes  100  in each of the rows are spaced at equal centerline-to-centerline intervals, or a uniform pitch, across the width of the equalizer plate  76 . The throughholes  100  in equalizer plate  76  and the slotted flow passageways  94  in equalizer plate  74  define a third stage or level of lateral and vertical thermoplastic material distribution in the linear flow equalizer  40 .  
         [0034]     Equalizer plate  78  is positioned downstream of the equalizer plate  76  and includes a plurality of slotted flow passageways  102  extending vertically through the thickness of equalizer plate  78  from an upstream inlet to a downstream outlet. A major axis of each slotted flow passageway  102  is aligned substantially in the cross-machine direction  45 . The center of each slotted flow passageway  102  is registered on an upstream surface  108  of equalizer plate  78  in substantial vertical alignment with one of the throughholes  100  in equalizer plate  76 , which define individual liquid inlets supplying flowable thermoplastic material to equalizer plate  78 . As a result, opposed curved terminal or closed ends  104 ,  106  of each slotted flow passageway  102  are substantially centered or symmetrical in the cross-machine direction  45  relative to the corresponding throughhole  100 .  
         [0035]     With continued reference to  FIG. 3 , equalizer plate  80  is positioned downstream of equalizer plate  78  and includes a plurality of flow passageways in the form of circular bores or thoughholes  110  extending vertically through the thickness of equalizer plate  80  from an upstream inlet to a downstream outlet. Each throughhole  110  is registered on an upstream surface  112  of equalizer plate  80  in substantial vertical alignment with one of the opposed closed curved ends  104 ,  106  of one of the slotted flow passageways  102 . Adjacent throughholes  110  in each of the rows are spaced at equal centerline-to-centerline intervals, or a uniform pitch, across the width of the equalizer plate  80 . The throughholes  110  in equalizer plate  80  and the slotted flow passageways  102  in equalizer plate  78  define a fourth stage or level of lateral thermoplastic material distribution in the linear flow equalizer  40 .  
         [0036]     The sheet-forming plate  82  includes opposed concavely-curved surfaces  114 ,  116  that integrate or merge the individual liquid flows streaming from the throughholes  110  of equalizer plate  80 . Sheet-forming plate  82  effectively eliminates gaps between adjacent streams of molten thermoplastic polymer exiting the throughholes  110  to form a substantially uniform sheet of flowable thermoplastic material that is provided to the combining plate  42 . The flowable thermoplastic material is subsequently filtered by the downstream filters  83 ,  84 ,  85  before being supplied to openings  86   a  extending through the filter support plate  86 .  
         [0037]     With reference to  FIG. 5A , each of the equalizer plate sets  50   a - c  may be provided in an equalizer plate  71  in which a set of channels  62   a  is formed. Each of the channels  62  includes multiple linear segments, of which only linear segment  64   a  is shown, arranged similarly or identical to channels  62  ( FIGS. 4 and 5 ). Channels  62   a  are intended to replace channels  62  in inlet plate  48  ( FIGS. 4 and 5 ). Consequently, an inlet plate  48   a  is modified to include three rows of inlet passageways  52   a  each of which supplies thermoplastic material to the center of one channel  62   a  for subsequent distribution to downstream equalizer plate  72 . Equalizer plate  71  is installed in recess  56   a  of inlet plate  48   a  between equalizer plate  72  and inlet plate  48   a  and also in the other two recesses in inlet plate  48   a  (not shown but similar to recesses  57  and  58  in  FIG. 3 ).  
         [0038]     The invention further contemplates that additional pairs of equalizer plates (not shown) may be disposed between equalizer plate  80  and sheet-forming plate  82  to provide additional symmetrical and equal divisions of the flowable thermoplastic material in the flow path through the linear flow equalizer  40 . The number of symmetrical and equal divisions will depend, among other variables, upon the width of the spin pack  32  in the cross-machine direction and, therefore, the width of the nonwoven web being formed by the spunbond system (not shown) with which spin beam assembly  10  is operative coupled.  
         [0039]     With renewed reference to  FIG. 3 , seal  87  provides a fluid-tight junction between a downstream side of the filter support plate  86  and an upstream side of the combining plate  42 . The combining plate  42  has internal liquid passageways  118  configured to receive the sheet-like flows of flowable thermoplastic materials from each of the linear flow equalizers  40  and to combine the flows to generate a bicomponent filament arrangement, such as a sheath/core arrangement or a side-by-side arrangement. In a sheath/core arrangement, for example, the flow path within the combining plate  42  of one of the two polymers is interposed and brought into coaxial alignment with the flow path of the other of the two polymers and directed the spinneret plate  44 . The spinneret plate  44  has multiple spinneret holes or orifices  120  registered with liquid outlets in the combining plate  42  from which bicomponent filaments  122  are extruded for subsequent solidification, attenuation and collection as a non-woven web.  
         [0040]     With reference to  FIG. 6 , the operation of the linear flow equalizer  40  will be further explained. The flow path for a flowable thermoplastic material  124  through the linear flow equalizer  40  in a downstream direction from each inlet passageway  52  in inlet plate  48  to each throughhole  110  in equalizer plate  80  is substantially equal to or, preferable equal to, all other flow paths for the flowable thermoplastic material in the linear flow equalizer  40 . Therefore, the linear flow equalizer  40  divides the flow evenly among all flow paths so that the residence time of any arbitrary volume of flowable thermoplastic material  124  flowing between inlet passageway  52  and the corresponding throughholes  110  is approximately equal and, preferably equal, and so that the properties (e.g., shear history) of the flowable thermoplastic material  124  exiting from each throughhole  110  are substantially identical and preferably equal.  
         [0041]     In the exemplary embodiment, the flowable thermoplastic material  124  entering the inlet passageways  52  is divided by inlet plate  48  into eight substantially equal portions, each of which is further subdivided by equalizer plates  72 ,  74  into two substantially equal portions. It is understood that the number of substantially equal portions created by inlet plate  48  is dependent upon the width of the inlet plate  48  and equalizer plate sets  50   a - c  in the cross-machine direction. Equalizer plates  76 ,  78  further subdivide the portions received from equalizer plate  74  again into two substantially equal portions and directed through equalizer plate  80  to the combining plate  42  ( FIG. 2 ). In the combining plate  42 , the thermoplastic material  124 , for example, Polymer A is combined with another thermoplastic material  126 , for example, Polymer B, which is subdivided uniformly in the linear flow equalizer  40  in a manner substantially similar to thermoplastic material  124 . The combined thermoplastic materials  124 ,  126  form bicomponent filaments  122 , such as the sheath/core arrangement illustrated in  FIG. 6 , that are discharged from the spinneret orifices  120  in the spinneret plate  44  as a curtain of filaments  122  for subsequent collection. The invention contemplates that additional thermoplastic materials may be combined with the thermoplastic materials  124 ,  126  to form multicomponent filaments  122  with more than two constituent thermoplastic materials and that the constituent thermoplastic materials may have other configurations, such as side-by-side.  
         [0042]     While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, the principles of the invention may be applied for the formation of filaments composed of a single polymer or of filaments formed from more than two polymers. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept. The scope of the invention itself should only be defined by the appended claims, wherein I claim: