Abstract:
A lamellar die apparatus for extruding a heated liquid into single or multiple component filaments. The apparatus includes a plurality of plates each having opposite side faces. At least two of the side faces confront each other and have a liquid passage positioned therebetween for transferring the heated liquid. At least two of the side faces confront each other and have a heating element passage therebetween. A heating element is positioned within the heating element passage for heating at least two of the plates. An extrusion die is coupled with the plurality of plates and communicates with the liquid passage for discharging the heated liquid as multiple filaments.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention generally relates to apparatus and methods for extruding thermoplastic filaments and, more particularly, apparatus for spunbonding multi-component or single component filaments.  
       BACKGROUND OF THE INVENTION  
       [0002]     Melt spinning techniques, such as spunbonding or meltblowing techniques, for extruding fine diameter filaments find many different applications in various industries including, for example, in nonwoven material manufacturing. This technology generally involves extruding a thermoplastic material from multiple rows of discharge outlets extending along the lower surface of an elongate spinneret. Spunbonded and/or meltblown materials are used in such products as diapers, surgical gowns, carpet backings, filters and many other consumer and industrial products. The machines for meltspinning such materials can be very large and include numerous filament discharge outlets.  
         [0003]     For certain applications, it is desirable to utilize two or more types of thermoplastic liquid materials to form individual cross-sectional portions of each filament. Often, these multi-component filaments comprise two components and, therefore, are referred to as bicomponent filaments. For example, when manufacturing nonwoven materials for use in the garment industry, it may be desirable to produce bicomponent filaments having a sheath-core construction. The outer sheath may be formed from a softer material which is comfortable to the skin of an individual and the inner core may be formed from a stronger, but perhaps less comfortable material having greater tensile strength to provide durability to the garment. Another important consideration involves cost of the material. For example, a core of inexpensive material may be combined with a sheath of more expensive material. For example, the core may be formed from polypropylene or nylon and the sheath may be formed from a polyester or co-polyester. Many other multi-component fiber configurations exist, including side-by-side, tipped, and microdenier configurations, each having its own special applications. Various material properties can be controlled using one or more of the component liquids. These include, as examples, thermal, chemical, electrical, optical, fragrance, and anti-microbial properties. Likewise, many types of die tips exist for combining the multiple liquid components just prior to discharge or extrusion to produce filaments of the desired cross-sectional configuration.  
         [0004]     One problem associated with multi-component extrusion apparatus involves the cost and complexity of the manifolds used to transmit liquid(s) to the spinneret or extrusion die. Typical manifolds are machined with many different passages to ensure that the proper flow of each component liquid reaches the die under the proper pressure and temperature conditions. These manifolds are therefore relatively complex and expensive components of the melt spinning apparatus.  
         [0005]     For these reasons, it would be desirable to provide a an extruding apparatus having a manifold system which may be easily manufactured while still achieving the goal of effectively transmitting the heated liquid or liquids to the die tip.  
       SUMMARY OF THE INVENTION  
       [0006]     The invention generally provides a lamellar die apparatus for extruding a heated liquid into filaments preferably by spunbonding techniques. The apparatus is constructed with a plurality of plates each having opposite side faces. At least two of the side faces confront each other and have a liquid passage positioned therebetween for transferring the heated liquid. At least two of the side faces confront each other and have a heating element passage therebetween. A heating element is positioned within the heating element passage for heating the liquid in the liquid passage. An extrusion die is coupled with the plurality of plates and communicates with the liquid passage for discharging the heated liquid as multiple filaments.  
         [0007]     The liquid passage is preferably formed by respective first and second recesses on adjacent plates that abut one another. Likewise, the heating element passage is formed by respective third and fourth recesses on adjacent plates that abut one another. Recesses from different ones of these pairs of recesses may, for example, be located on opposite sides of the same plate. In the preferred embodiment, multiple heating element passages are positioned between two of the plates and multiple heating elements are respectively contained in the heating element passages.  
         [0008]     The liquid passage includes an inlet portion and an outlet portion with the outlet portion being wider than the inlet portion. The outlet portion of the liquid passage forms an elongate liquid outlet slot. The extrusion die includes an elongate liquid inlet slot aligned in communication with the elongate liquid outlet slot to facilitate liquid flow to the extrusion outlets.  
         [0009]     The invention further contemplates methods of extruding liquid filaments, such as single or multiple component thermoplastic polymeric filaments, in general accordance with the use of the apparatus described above.  
         [0010]     Various advantages, objectives, and features of the invention will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is an exploded perspective view of a multi-component spunbonding apparatus constructed in accordance with a preferred embodiment of the invention.  
         [0012]      FIG. 2  is a cross sectional view taken along line  2 - 2  of  FIG. 3 .  
         [0013]      FIG. 3  is a fragmented top view of the assembled apparatus of  FIG. 1  taken generally along line  3 - 3  of  FIG. 2 .  
         [0014]      FIG. 4  is a cross sectional view similar to  FIG. 2 , but illustrating an alternative embodiment of the apparatus and taken along line  4 - 4  of  FIG. 5 .  
         [0015]      FIG. 5  is a cross sectional view taken along line  5 - 5  of  FIG. 4 .  
         [0016]      FIG. 6  is a cross sectional view similar to  FIG. 2 , but illustrating another alternative embodiment of the apparatus.  
         [0017]      FIG. 7  is a cross sectional view similar to  FIG. 4 , but illustrating another alternative embodiment of the apparatus. 
     
    
     DETAILED DESCRIPTION  
       [0018]      FIGS. 1-3  illustrate a die apparatus  10  constructed in accordance with a first embodiment. Apparatus  10  is comprised of a manifold structure  12  coupled for fluid communication with an extrusion die  14 . Manifold structure  12  is a lamellar construction or plate assembly comprised of multiple plates  16   a - c ,  18   a - c  and  20 . These plates are securely fastened together in side-by-side relation using appropriate fasteners  22  (only one shown in  FIGS. 2 and 3 ) extending through holes  24  in each of the plates. As best shown in  FIG. 2 , respective outside pairs of plates  16   a ,  16   b  and  18   a ,  18   b  form optional air manifold sections and include respective quench air input ports  26 ,  28 . Positive pressure quench air assists in quickly cooling the discharged filaments. Optionally, vacuum may be drawn through ports  26 ,  28  for purposes of removing monomer gases at the filament discharge area. In each case, it will be understood that the appropriate openings (not shown) will be provided in or adjacent die  14  to allow the discharge of quench air or intake of monomer gases. Plates  16   a ,  16   b  and  18   a ,  18   b  respectively abut each other and contain air passages  27 ,  29  therebetween. Air passages  27 ,  29  are respectively formed by pairs of recesses  30 ,  32  and  34 ,  36  that align with each other in abutting faces of the plates  16   a ,  16   b  and  18   a ,  18   b.    
         [0019]     As shown best in  FIG. 1 , these recesses  30 ,  32  and  34 ,  36  take the form of so-called coat hangar recesses which become wider in dimension from the inlet portion  40  located proximate input ports  26 ,  28  to an outlet portion  42  located proximate respective distribution passages  44 . Distribution passages  44  extend respectively through plates  16   b  and  18   b  and lead to extrusion die  14 . Plates  16   c  and  18   c  respectively abut central plate  20  as shown.  
         [0020]     Respective liquid passages  54 ,  56  are formed between plates  16   c ,  20  and  18   c ,  20  and, again, are formed by respective pairs of coat hangar recesses  58 ,  60  and  62 ,  64  that align with each other in abutting surfaces of these plates  16   c ,  20  and  18   c ,  20 . As shown in  FIG. 1A , these recesses  58 ,  60  and  62 ,  64  are also formed with a coat hangar configuration between inlet portions adjacent respective liquid input ports  66 ,  68  and outlet portions which form elongate liquid outlet slots  70 ,  72  for abutting the top surface of the extrusion die  14  and aligning with coextensive liquid inlet slots  73 ,  75 . In this embodiment, the two liquid input ports  66 ,  68  and coat hangar passages  54 ,  56  are provided for producing bicomponent filaments from extrusion die  14 . Extrusion die  14  may be any suitable extrusion die having, for example, a laminated plate construction with appropriate porting and passages to combine and extrude filaments from the outlet orifices extending along the underside of the extrusion die  14  and to attenuate or otherwise affect those filaments with process air. Representative dies are, for example, disclosed in U.S. Pat. Nos. 5,562,930; 5,551,588; and 5,344,297, however, such dies would require modification with suitable passages to transfer and discharge quench air received from distribution passages  44 .  
         [0021]     Also in accordance with the invention, heating elements  74 ,  76  are respectively contained in passages  80 ,  82  between plates  16   b ,  16   c  and  18   b ,  18   c . Each passage is again preferably formed by respective pairs of aligned and abutting recesses  84 ,  86  and  88 ,  90  in plates  16   b ,  16   c  and  18   b ,  18   c . These heating elements  74 ,  76 , which are preferably electrically operated heating elements, may be advantageously situated between the respective air and liquid passages  27 ,  54  and  29 ,  56  so as to heat both the liquid and the air traveling to extrusion die  14 . Sufficient heat may also be supplied to heat the extrusion die  14  itself to the appropriate operating temperature.  
         [0022]      FIGS. 4 and 5  illustrate another apparatus  10 ′ constructed in accordance with the invention. In this embodiment, apparatus  10 ′ again comprises a multiple plate assembly or manifold structure  12 ′ coupled with an extrusion die  14 ′. Manifold structure  12 ′ and die  14 ′ are similar to the first embodiment except that a five plate construction is used instead of a seven plate construction thereby eliminating the quench air. In this embodiment, plates  16   a ,  18   a  have been eliminated from the outside of the manifold structure  12 ′ to eliminate the quenching air to the extrusion die  14 ′. This quenching air can instead be discharged at the filaments by other means such as conventional components located below die  14 ′. Other elements indicated with like reference numerals to the first embodiment but have prime mark (′) designations are only slightly modified as shown. Elements having like numerals to the first embodiment are identical elements. In both cases, no further description is necessary to an understanding of the invention.  
         [0023]      FIG. 6  illustrates another alternative die apparatus  200  having a laminated plate construction. This apparatus  200  is similar to that described above with respect to the first embodiment ( FIGS. 1-3 ), but is configured to discharge single component filaments or monofilaments rather than a bicomponent filament. Thus, the central plate  20  used in the first embodiment has been eliminated thereby resulting in a six plate construction rather than a seven plate construction for manifold structure  202 . As with the previous embodiments, an extrusion die  204  is coupled to manifold structure  202  for discharging one or more filaments and, optionally, discharging quenching air. A single liquid input port  206  and coat hanger passage  208  receive the liquid, such as a thermoplastic polymer. Coat hanger passage  208  is formed by aligned recesses  210 ,  212  in abutting faces of plates  16   c ′ and  18   c ′. Plates  16   c ′ and  18   c ′ are designated with prime marks (′) to denote that they are slightly modified, as illustrated, from plates  16   c ,  18   c . All other aspects of apparatus  200  are as described above with respect to the first embodiment and, therefore, identical reference numerals have been used and no further description is necessary.  
         [0024]      FIG. 7  illustrates another alternative apparatus  220  similar to that described above with respect to  FIGS. 4 and 5  but, like the embodiment of  FIG. 6 , apparatus  220  is configured to discharge single component filaments or monofilaments rather than bicomponent filaments. Again, the central plate  20  of the embodiment illustrated in  FIGS. 4 and 5  has been eliminated and a four plate manifold structure  222  results. Manifold structure  222  is configured to deliver a single type of liquid, such as a thermoplastic polymer, to an extrusion die  224 . A single liquid input port  206  and a coat hanger passage  208  is formed between abutting plates  16   c ′,  18   c ′ to communicate with an appropriate elongate inlet slot (not shown) in the top of the extrusion die  224 . Plates  16   c ′ and  18   c ′ are identical to those shown in  FIG. 6 . All other aspects of the embodiment shown in  FIG. 7  are described with respect to the first two embodiments described above and, therefore, identical reference numerals have been used and no further description is necessary.  
         [0025]     While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments has been described in some 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. The various features of the invention may be used alone or in numerous combinations depending on the needs and preferences of the user. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known. However, the invention itself should only be defined by the appended claims, wherein we claim: