Patent Publication Number: US-7210914-B2

Title: Series apparatus for forming layered fibrous mat of differing fibers and controlled surfaces

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional of U.S. patent application Ser. No. 10/028,189, filed on Dec. 20, 2001, now U.S. Pat. No. 6,736,914, issued on May 18, 2004. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a method, apparatus and product relating to fibrous mat and more particularly to a unique and novel arrangement for making fibrous mat in such a combined manner that the resulting attenuated fibrous layered mat has fiber layers, each of select fiber size distribution and, if elected a controlled surface and variable permeability. 
   The present invention has particular applicability to polymer fibrous mat produced by melt blowing die apparatus but it is to be understood that the present invention can be readily utilized in layered mat production where in layered fibrous mats of other fibrous materials in addition to preselected polymer material—such as glass—are extracted in die attenuated form from heated die sources unto spaced collector sources. 
   Layered fibrous mat composed of fibers attenuated from a heated die source unto a space layered matt collector surface are generally well known in both the glass and melt blown arts but none have utilized the unique and novel unified arrangement disclosed herein. Although, as above-noted, the present invention is not be considered as limited to die feeding polymer materials from heated melt blown die sources, the unique and novel arrangement set forth herein has particular applicability in the melt blowing die feeding arrangements as disclosed in the U.S. Pat. No. 5,725,812, issued to Kyung-Ju Choi on Mar. 10, 1998; U.S. Pat. No. 5,891,482, issued to Kyung-Ju Choi on Apr. 6, 1999; U.S. Pat. No. 5,976,209, issued to Kyung-Ju Choi on Nov. 2, 1999; U.S. Pat. No. 5,976,427, issued to Kyung-Ju Choi, also on Nov. 2, 1999; U.S. Pat. No. 6,159,318, issued to Kyung-Ju Choi on Dec. 12, 2000; and U.S. Pat. No. 6,230,776, issued to Kyung-Ju Choi on May 15, 2001. 
   The external treatment of fibers with respect to a fiber collecting source is generally well known in the production of non-woven fabrics, attention being directed to U.S. Pat. No. 4,095,312, issued to D. J. Haley on Jun. 20, 1978, wherein fibers are collected from two fiber feeding sources to a pair of moving collecting surfaces to form a nip; to U.S. Pat. No. 4,100,324, issued to R. A. Anderson, et al. on Jul. 11, 1978, wherein wood pulp fibers are added to a matrix of collected polymeric melt blown microfibers; to U.S. Pat. No. 4,267,002, issued to C. H. Sloan on May 21, 1981, wherein fibers are formed in elongated rod shape with a heavy build-up in a central portion and a light build-up in a lip portion folded back over the central portion; to U.S. Pat. No. 4,375,446, issued to S. Fujii, et al. on Mar. 1, 1983, wherein melt blown fibers are collected in a valley-like fiber-collecting zone formed by relatively moveable and compressible porous plates which have a controlled number of pores; and, finally to U.S. Pat. No. 4,526,733, issued to J. C. Lau on Jul. 2, 1955, wherein a fluid stream of attenuated fibers is preselectively temperature treated upon exiting die tip orifices to provide improved collected web properties. 
   Although these above-noted patents disclose various external treatments of fiber streams attenuated from heated die sources, none teaches or suggests, either alone or in combination, the economical and straight-forward arrangement which includes successively feeding and combining fiber layers, each layer having select fiber size distributions and, if elected, the novel diversion and vortically creating force exertion of a selected portion of fiber streams to provide fiber layers with select fiber size distributions, selected surface, and, selected variable permeability of the total fibrous mat as it passes to a fiber collecting source. 
   The present invention provides a unique and novel die attenuated fiber arrangement including a straight-forward, economical and inventively unified production method, apparatus and final layered, relatively strong fibrous mat product which allows for efficient and economic control of fiber size distribution, surface, and permeability of a layered fibrous mat product which can have selected fiber size distributions, variable density, permeability and surface. 
   The present invention accomplishes the unique features thereof with a minimum of apparatus, parts, elements, and method steps in both manufacture and maintenance and, at the same time, which allows for ready adjustment to control variable fiber mat density, fiber distribution, mat permeability and surface in selected areas of a produced fibrous mat. 
   Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein. 
   BRIEF SUMMARY OF THE INVENTION 
   More particularly the present invention provides a unified, unique and novel method, apparatus and product arrangement in the production of die attenuated fibrous mat which can be utilized in any number of commercial environments—one of which being the fluid filtration art. 
   Specifically, the present invention provides a unique and novel method of forming a web of fibrous media comprising: feeding fibers in attenuated multiple fiber layers from a first spaced orifice zone in a first feed path to a first selectively spaced, longitudinally extending, rotating collector zone in successive lower and upper fiber layers, the first fibers having a first selected fiber size distribution when passed to the first collector zone to form a first fibrous mat having a first selected fiber size distribution; feeding the first formed fibrous mat to at least a second similarly rotating collector zone selectively spaced from the first rotating collector zone; feeding second fibers in attenuated multiple fiber layers from a second spaced orifice zone in a second feed path to a second similarly rotating collector zone selectively spaced from the second orifice zone to form a second fibrous mat combined with the first fibrous mat fed to the second collector zone from the first collector zone, the second fibers having a second selected fiber size distribution and, feeding the combined fiber mat from the second collector source zone to a third mat forming zone. 
   In addition, the present invention provides several embodiments of method steps for controlling the outer surface or surfaces of the web of filter media formed by the novel method embodiments described herein. 
   Further, the present invention provides in a unified manner, a unique and novel mat of fibrous media comprising: at least a first layered mat portion of selected first fiber size distribution and permeability and at least a second layered mat portion of selected second fiber size distribution, and permeability, both the first and second layered mat portions being of substantially aligned fibers of first and second selected fiber size distributions, and permeabilities with each being attenuated as layers from spaced die sources directly to separate spaced similarly rotating collector sources with one of such sources receiving the layered mat portion from the other of the spaced collector sources. 
   In addition, the present invention provides apparatus for manufacturing a fibrous mat comprising a first die source including spaced die orifices capable of feeding a first attenuated multiple fiber layered portion; a first selectively gap spaced longitudinally extending first rotating collector surface to eventually receive the totality of the first layered portion; at least a spaced second die source including spaced die orifices capable of feeding a second attenuating multiple fiber layered portion; a second selectively gap spaced longitudinally extending second similarly rotating collector surface to eventually receive the totality of the second fiber layered portion, the second rotating collector surface being spaced from the first rotating collector surface; and, transfer and orientation means positioned between the first and second collector surfaces to orient and transfer the first layered mat portion from the first rotating collector surface to a select quadrant of the second similarly rotating collector surface. 
   Moreover, the present invention provides several novel rotating collector surface embodiments associated with the unique apparatus described herein to control the nature, permeability and strength of the outer surfaces and the fiber composition therebetween of the novel fibrous media mat described herein. 
   It is to be understood that various changes can be made by one skilled in the art in the several steps of the method and the several elements and parts of the product and apparatus herein disclosed without departing from the scope or spirit of the present unified invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings which disclose several advantageous embodiments of the present invention and modifications thereto: 
       FIG. 1  is a schematic side view of one embodiment of the novel apparatus of the present invention; 
       FIG. 1A  is a schematic front view of one embodiment of a cylindrical rotatable collector showing a perforated surface; 
       FIG. 2  is a schematic side view similar to that of  FIG. 1 , further disclosing a novel collector-like vortically creating force deflector; 
       FIG. 3  is a schematic, cross-section of a portion of a novel fibrous mat produced by the novel apparatus of  FIG. 1 ; 
       FIG. 4  is another schematic, cross-section of a portion of a novel fibrous mat produced by structure similar to that of  FIG. 1  and including the novel apparatus of  FIG. 2 ; 
       FIG. 5  is a schematic side view of a second embodiment of the novel apparatus of the present invention; 
       FIG. 6  is a schematic cross sectional side view of a fibrous mat produced by the arrangement of  FIG. 5 ; 
       FIGS. 7 and 8  are schematic side views of a third embodiment of the novel apparatus and cross-sectional side view of the fibrous mat produced thereby; 
       FIGS. 9 and 10  are views like  FIGS. 5–8  disclosing a fourth embodiment of the present invention; 
       FIGS. 11 and 12  are views similar to  FIGS. 5–10 , disclosing a fifth embodiment of the present invention; and, 
       FIG. 13  is a schematic chart disclosing the comparative bond strength in pounds from spaced stations extending from edge to edge of a fibrous mat of the present invention when compared with two commercially competitive fibrous mats. 
   

   DETAILED DESCRIPTION OF THE DRAWINGS 
   Referring to  FIG. 1  of the drawings, one embodiment  2  of the novel apparatus of the invention is disclosed for forming the unique layered web of fibrous media in accordance with the inventive overall arrangement described herein. 
   The overall arrangement of embodiment  2  includes three spaced successive similar fibrous mat forming structures,  3 ,  4  and  6 . Each of these three structures includes a first melt blow die source  7  which includes spaced die orifices  8 , each capable of feeding one of three fiber feed paths of attenuated multiple filter fiber layer portions to one of three longitudinally extending, cylindrical rotatable collectors  11 , each of which collectors has a peripheral, perforated collector surface  25  selectively spaced from and aligned with the first melt blown die source  7  including spaced die orifices  8 .  FIG. 1A  shows the perforated collector surface  25  of cylindrical rotatable collector  11 . A suitable motor and gear driven system (now shown) can be provided to rotate each perforated collector  11  in a selected clockwise rotational direction, as shown by the rotational arrow of  FIG. 1 . It is to be understood that each perforated rotatable collector  11  eventually receives the selected totality of the filter fiber layered portion from its fiber feed path and that each collector  11  can be provided with an appropriate internal coolant or vacuum source  12 , the internal piping and expansive arrangement being disclosed schematically in  FIG. 1  and is similar to that as shown in above U.S. Pat. No. 6,159,318 and No. 6,230,775. In an advantageous embodiment of the present Invention collectors  11  can be selectively spaced from die orifices  8  approximately in the range of two (2) to sixty (60) inches and preferably approximately eighteen (18) inches. The polymer volumes and air pressure at the die are appropriately selected for making the particular filter medium. 
   To accomplish the transfer of layered fiber portions from one spaced, perforated rotating collector  11  to the next adjacent collector  11 , longitudinally extending idler rolls  13  are positioned between collectors  11 . These idler rolls  13  are positioned relative to the three spaced rotating collectors  11 , in accordance with one feature of the present invention, so that the layered mat portion formed on the peripheral surface of a preceding rotatable collector  11  passes from its first cross-sectional quadrant in its rotational direction in oriented fashion along spaced idler rolls  13  to an adjacent rotatable spaced collector  11  so as to be fed to such adjacent rotatable collector  11  along the fourth cross-sectional quadrant that—is advantageously between approximately ninety (90°) degrees of a preceding cross-sectional quadrant to an approximately two hundred seventy (270°) degrees of an adjacent, following collector cross-sectional quadrant. 
   It is to be understood that, in one embodiment of the present invention, the fibrous layer portion of one fibrous feed path  9  can be superposed above the fibrous layer of another or vice versa—all in accordance with appropriate motor and drive gearing, as well as feed timing (not shown). Also, in accordance with another embodiment of the present invention, it would be possible to selectively intersperse the fibers of the two fibrous layer portions of fibrous feed paths  9 . 
   Further, in other features of the present invention, the fibrous filter media mat formed in portions on the successive mat forming structures,  3 ,  4 , and  6 , as above described, which mat is subsequently passed to an additional work forming station (also not shown in detail but shown schematically as block  14 ) can be of selective composition fiber size distributions, and web permeability. 
   Advantageously, the first layered filter media mat portion formed by a feed path  9  from die orifices  8  can be of synthetic composition with fiber size distributions, being in the approximate range of zero point one (0.1) to twenty-seven (27) micrometers and the permeability range of five (5) to two thousand (2000) cubic feet per minute per square foot (cfm/ft 2 ). The second layered filter media mat portion formed by a feed path  9  from die orifices  8  can be of similar synthetic melt blown composition with fiber size distributions in the approximate range of one (1) to fifty (50) micrometers and the permeability can be in the approximate range of thirty (30) to four thousand (4000) cubic feet per minute per square foot (cfm/ft2). The third layered portion also can be of similar composition within similar selected fiber size distribution and permeability ranges as the second layered portion. 
   Referring to  FIG. 2  of the drawings, still another additional structural feature of the present invention can be seen. This additional structural feature can be included with any one or more of the mat forming structures  3 ,  4  and  6  like that shown in  FIG. 1 , as might be elected and in accordance with the specific nature of a fluid stream to be treated. 
   In a manner similar to that of co-pending application Ser. No. 09/635,310, filed on Aug. 9, 2000, now U.S. Pat. No. 6,596,205 issued on Jul. 22, 2003, a direction and external vortically creating force in the form of counter-clockwise rotational, cylindrical drum  16 , which is of smaller surface than the clockwise rotational cylindrical collector  11  having perforated surface  25 . The drum  16  is gap-spaced a preselected distance from collector  11  so as to exert an external vortically creating force on a preselected portion of the multiple fiber sheet before that portion is reformed on collector  11  to join the remaining portions of the multiple fiber sheet. This action of counter-rotational diverter drum  16  serves to curl the fibers when returned to the rotatable collector  11 . It is to be understood that the diverting arrangement as shown, as well as such other diverting arrangements disclosed in the aforementioned co-pending application, can be employed with the collectors as shown and with other collectors which might be added to the overall mat forming structures. 
   In summary and in carrying out one embodiment of the present invention in accordance with the mat forming structures  2 ,  4  and  6  of  FIG. 1  with fibers in the size range of zero point one (0.1) to fifty (50) micrometers as elected for each of the structures  3 ,  4  and  6 , first filter fibers are fed in a first feed zone from spaced melt blow orifices, the first filter fibers being of synthetic melt blown composition with a permeability in the approximate range of five (5) to two thousand (2000) cubic feet per minute per square foot (cfm/ft 2 ) and a fiber size distribution in the approximate range of zero point one (p.1) to twenty seven (27) micrometers, the fibers forming a first portion of a combined filter mat on a first rotating cylindrical collector zone in successive lower and upper first layers in the first zone. The first portion of the mat is then passed through a filter mat orientation feed zone to second and third spaced similarly rotating collector zones to peripherally collect thereon. 
   More specifically, In the second and third filter zones, fibers which also can be of synthetic melt blown compositions are fed in like feed paths  9  from second and third spaced melt blown orifices  8 , the second and third fibers in feed paths  9  having permeability in the approximate range of thirty (30) to four thousand (4000) cubic feet per minute per square foot (cfm/ft2) and fiber size distributions in the approximate range of one (1) to fifty (50) micrometers. The second and third fiber paths  9  are fed to second and third spaced rotating collector zones  11  in successive lower and upper fiber layers or in an interspersed manner with fibers from the preceding zone or zones forming a second and third portions of the combined filter mat with preceding portions of the mat. The combined mat portions are then passed to a further work zone (shown schematically as block  14 ). 
   It is to be understood that, if desired, the vortically creating external forces as above discussed, can be employed in one or more of the collecting zones so as to produce curled, entangled fibers, on at least a portion of inventive layered mat. It further is to be understood that in accordance with another feature of the invention that in each of the mat forming structures  3 ,  4  and  6 , the spacing between die orifices  8  and rotating cylindrical collectors  11  in each mat forming structure advantageously is of significant import and advantageously should be in the range of approximately two (2) to sixty (60) inches. 
   Referring to  FIGS. 3 and 4  of the drawings, schematic cross-sections of two fibrous mats  17  and  18  can be seen, fibrous mat  17  having been produced by apparatus similar to that shown in  FIG. 1  of the drawings and mat  18  having been produced by apparatus also similar to that shown in  FIG. 1  but which also includes a vortically creating force deflector structure ( FIG. 2 ) cooperative with at least one of the rotatable cylindrical drums of the structure of  FIG. 1 . 
   It is to be noted in  FIGS. 3 and 4  that the outer surfaces  19  and  21 , here shown respectively in each of  FIGS. 3 and 4  as the upper surface, is of a smooth, skin-like nature as distinguished from the lower surfaces in each figure. This is a consequence of selectively attenuating fibers of a comparatively smaller fiber size distribution into the feed path of either the first or last fibrous producing layers in mat forming structures  3  or  6 . 
   It is to be understood that either the first, last or both such end fibrous mat producing layer structures can be so arranged to produce such a desired outer surface with the final mat produced work product at  14  being appropriately inverted, as might be occasioned. 
   It further is to be noted in  FIGS. 3 and 4  that the lower layers  22  and  23  of mats  17  and  18  respectively are selectively of coarser nature, the attenuated fibers being of comparatively greater fiber size distribution. Moreover, lower layer  23  of  FIG. 4  is shown as entangled as the consequence of the aforedescribed vertical force filter displacement by counter-rotating small drum structure as shown in  FIG. 2 . 
   In  FIGS. 5 and 6 , another embodiment of the present invention can be seen. In this embodiment, spaced mat forming structures  24  and  26  are disclosed. Each mat forming structure includes a melt blown die source  27  with die orifices  28  adapted to have attenuated therefrom fiber feed paths  29  unto spaced, cylindrical, fluid pervious, rotatable cylindrical collectors  31 , each collector including coolant or vacuum piping with expanders  32  at the distal end and a perforated surface  35 . A triangularly spaced idler roller set  33  is positioned between the two spaced fluid pervious rotatable, cylindrical collectors  31  and an idler roller  34  is positioned below the later of collectors  31  to receive and direct the layered fibrous mat to a following location. In this embodiment of the invention, only two spaced rotatable collectors  31  are disclosed. These perforated collectors  31 , like the three spaced perforated collectors  11  of  FIG. 1 , are shown to rotate in the same direction and to receive fiber feed paths  29  attenuated from orifices  28  in the first cross-sectional quadrant of each collector in a manner similar to the feed paths  9  and collectors  11  arrangement of  FIG. 1 . 
   The resulting layered melt blown fibrous mat  36  can be seen in the schematic cross-sectional drawing ( FIG. 6 ) to include a smooth skin-like outer surface  37  formed by the finer attenuated fiber layer  38  having comparatively smaller fiber size distribution than the coarser attenuated fiber layer  39 . 
   Referring to  FIGS. 7 and 8 , still another embodiment of the present invention can be seen. In this embodiment, spaced mat forming structures  41  and  42  can be seen. Each structure includes a melt blown die source  43  with die orifices  44  serving to have attenuated therefrom fiber feed paths  46  unto spaced cylindrical, fluid pervious rotatable cylindrical collectors  47  having perforated collector surfaces  45 , each collector including coolant or vacuum piping with a distal expanders  48 --the structure described so far being comparable to that structure of  FIGS. 5 and 6  except for a single idler roll  50  being positioned between the spaced rotating collectors  47  and except for the fact that the cylindrical rotatable collectors  47  are rotated in opposite directions from each other. It also is to be noted in this embodiment of the invention that the fiber feed paths  46  are directed to the fourth cross-sectional quadrant of the collectors as distinguished from the first cross-sectional quadrant--as can be seen in  FIGS. 1 and 5 . 
   In the embodiment of the invention of  FIG. 7  and as can be seen in  FIG. 8  disclosing a schematic cross-sectional view of a layered fibrous mat  49  produced by the mat forming arrangement of  FIG. 7 , fine fiber layers  51  and coarse fiber layers  52  are shown with both outer surfaces  53  and  54  having comparatively smooth, skin-like properties. As above discussed, the finer fibers of layers  51  have comparatively smaller fiber size distribution properties than the coarser layers  52 . 
   In still another embodiment of the invention as disclosed in  FIGS. 9 and 10  of the drawings, mat forming structures  56  and  57  can be seen. Like that of  FIG. 7  each structure  56  and  57  includes a melt blown die source  58  with the die orifices  59  serving to have attenuated therefrom fiber feed paths  61  unto spaced cylindrical, fluid pervious, rotatable cylindrical spaced collectors  62 , each collector including coolant or vacuum piping with a distal expander  63  in flow communication with perforated surface  65 . 
   In this embodiment of  FIG. 9 , the spaced collectors  62  are shown as rotating in the same direction. However, the fiber feed path  61  in the mat forming structure  56  is directed to the cross-sectional first quadrant of rotatable collector  62  whereas the fiber feed path  61  in mat forming structure  57  is directed to the cross-sectional fourth quadrant of its rotatable collector  62 . A suitable idler roll  64  is shown positioned between spaced rotatable collectors  62  to direct the produced fibrous layers from one rotatable collector  62  to the other spaced fluid pervious rotatable collector  62 . 
   As above, the produced fiber layers can be of coarse and fine fibers with the fine fibers of one fiber feed path  61  having a smaller fiber size distribution than the fiber feed path of the other fiber feed path  61 . 
   Referring to  FIG. 10 , the cross-section of a portion of a fibrous matt  66  can be seen as produced by and arrangement such as disclosed in  FIG. 9 . This mat is shown as including layers  67  of fine fibers and layers of coarse fibers  68 . In this embodiment, both outer surfaces  69  and  71  have been formed so as to be of smooth, skin-like nature. 
     FIGS. 11 and 12  show still a further embodiment of the present unified invention  FIG. 11  is shown to include melt blown mat forming structures  72  and  73 , each of which includes melt blown die source  74  with die orifices  76  serving to have attenuated therefrom fiber feed paths  77  unto spaced, cylindrical, fluid pervious, rotatable cylindrical collector  78  having perforated surfaces  75 . As above, for  FIG. 9 , each collector  78  includes coolant or vacuum piping with a distal expander  79 . 
   In this  FIG. 11  the spaced rotatable, cylindrical collectors are shown as rotatable in opposite directions with fiber feed paths  77  being directed to the first cross-sectional quadrant of each rotatable collector. A suitable idler roll  81  can be seen positioned between spaced collectors  78 . 
   In the embodiment of  FIG. 12 , fiber attenuation paths  77  for mat forming structures  72  and  73  can be of coarse and fine fibers, respectively with the finer fibers having a smaller fiber size distribution than the coarser fibers. 
   Referring to  FIG. 12 , the cross-section of a portion of a fibrous mat  82  can be seen as produced by an arrangement such as disclosed in  FIG. 11 . This mat  82  is shown as including layers  83  of fine fibers and layers of coarse fibers  84 . As in  FIG. 10 , both outer surfaces  86  and  87  have been formed so as to be of smooth, skin-like nature. 
   This, in accordance with the several embodiments of the unified invention disclosed, it can be seen that relatively strong webs of fiber medium can be produced form spaced die attenuating structures advantageously of the melt blown type but not necessarily limited thereto with fiber feed paths feeding attenuated fibers of selective fine and coarser nature over a selective distance and in a selectively contacting manner to spaced rotatable cylindrical collectors which, in the several embodiments disclosed, can be rotated in different manners with respect to each other. The resulting fibrous mat products—which are particularly suited for fluid filtration, provide a number of unique and novel features to the filtration art, including controlled outer smooth, skin-like fibrous mat surfaces which serve to minimize the amount of loose fibers on the web surface. And, as can be seen in  FIG. 13 , the fibrous mat of the present invention provides an increased bond strength in pounds when the inventive mat is compared to two well known other fibrous mats which are now available on the commercial market. 
   In this regard, the chart of  FIG. 13 , compares bond strengths in pounds across eight (8) edge-to-edge spacer stations of an inventive fibrous mat product as represented by the full line  88  when compared in performance with the two other commercially available fibrous mat products represented by longer dash line  89  and the shorter dash line  91 .