Patent Publication Number: US-2007098984-A1

Title: Fiber with release-material sheath for papermaking belts

Description:
FIELD OF INVENTION  
      The present invention relates to papermaking belts. More particularly, the present invention concerns fibers with release-material sheaths, methods and systems for making such fibers, papermaking belts incorporating such fibers, and papermaking processes using belts incorporating such fibers.  
     BACKGROUND  
      Considerable efforts have been devoted to increasing the efficiency and reducing the costs of making various types of paper, including facial tissue, paper towels, bathroom tissue, and napkins. As part of this effort, there have been numerous attempts to improve the durability and/or release properties of papermaking belts (i.e., the belts and fabrics used during one or more stages of a papermaking process to carry a fibrous web that is being made into paper).  
      For example, U.S. Pat. Nos. 6,701,637 and 6,514,382 describe the application of release coatings (e.g., fluoropolymers and silicone release agents) to papermaking belts to reduce the tendency of the fibrous web to stick to the belt. These release coatings, however, are temporary and need to be reapplied, thereby increasing costs.  
      To avoid or minimize the use of temporary chemical release agents, WO 03/057977 A2, an international application published under the PCT, describes “papermaking belts and industrial textiles with enhanced surface properties.” This application discusses the use of a primer to graft a resin system onto a textile fabric after the surface of the fabric has been sanded. (Belt fabric is typically sanded to increase its surface contact area.) The resin system “provides a number of benefits including the enhancement of hydrophobic properties giving superior paper web sheet release thus eliminating or at least minimizing the need to continuously apply a temporary chemical release agent to the TAD (through-air drying) fabric.” 
      The belts described in WO 03/057977 A2, however, suffer from several deficiencies and shortcomings. The resin may not uniformly cover the fabric, thereby increasing the amount of temporary chemical release agent that needs to be applied to the fabric belt to provide acceptable release properties. Moreover, the use of a primer increases the complexity of the fabrication process.  
      In another example, WO 00/51801 describes a transfer fabric that “employs a sheath-core composite yarn which may be heated on one or both surfaces so that the sheath component is melted. Melting produces a support layer which is non-porous or substantially non-porous. The core of each yarn [which has a higher melting temperature than the sheath component] is unaffected by melting and thus becomes embedded in the support layer.”  
      The belts described in WO 00/51801 also suffer from several deficiencies and shortcomings. The sheath material (e.g., polyurethane) is a tacky substance, not a non-sticking material. Thus, there is no reduction in the amount of temporary chemical release agents that must be repeatedly applied to these belts to provide adequate release properties.  
      In another example, WO 99/05358 describes “yarns or fibres which have been subjected to plasma treatment.” “To provide a water-repellant finish (hydrophobic) the plasma may be created from a siloxane or perfluorocarbon compound.” One advantage cited in WO 99/05358 for plasma treatment is that “very small amounts of the raw materials are required (e.g., 30-100 mg per m 2  fabric).” 
      The belts described in WO 99/05358 also suffer from several deficiencies and shortcomings. The material deposited on the yam or fiber by the plasma is so thin (e.g., 30-100 mg per m 2  corresponds to 150-500 Angstroms for a material with a density of 2 gm/cm 3 ) that the material will not be durable. Indeed, most or all of the material would be removed from belts made of plasma-treated yarn if the belts were sanded.  
      Thus, there remains a need for improved papermaking belts with better durability and release properties.  
     SUMMARY  
      The present invention addresses the needs described above by providing fibers with release-material sheaths, methods and systems for making such fibers, papermaking belts incorporating such fibers, and papermaking processes using belts incorporating such fibers.  
      One aspect of the invention involves a fiber for use in a papermaking belt. The fiber includes an inner core and an outer sheath. The outer sheath has a thickness of at least 10 microns prior to sanding, if any, of the fiber, and includes a release material to facilitate the release of a paper web when the paper web is in contact with the fiber.  
      Another aspect of the invention involves a method for making a fiber. The method includes forming a fiber core and forming an outer sheath around the fiber core. The outer sheath has a thickness of at least 10 microns prior to sanding, if any, of the fiber, and includes a release material to facilitate the release of a paper web when the paper web is in contact with the fiber.  
      Another aspect of the invention involves a papermaking belt that includes a mesh of fibers. At least some of the fibers include an outer sheath integrally formed around an inner core. The outer sheath has a thickness of at least 10 microns prior to sanding, if any, of the belt, and includes a release material to facilitate the release of a fibrous web of paper when the web is in contact with the belt.  
      Another aspect of the invention is a method of intermeshing a plurality of fibers to form a papermaking fabric. At least some fibers in the plurality of fibers include an outer sheath integrally formed around an inner core. The outer sheath has a thickness of at least 10 microns prior to sanding, if any, of the fabric, and includes a release material to facilitate the release of a fibrous web of paper when the web is in contact with the fabric.  
      Another aspect of the invention is a method of using a papermaking belt to carry a fibrous web in at least one part of a papermaking process. The papermaking belt includes a mesh of fibers. At least some of the fibers include an outer sheath integrally formed around an inner core. The outer sheath has a thickness of at least 10 microns prior to sanding, if any, of the belt, and includes a release material to facilitate the release of a fibrous web of paper when the web is in contact with the belt.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      For a better understanding of the aforementioned aspects of the invention as well as additional aspects and embodiments thereof, reference should be made to the Description of Embodiments below, in conjunction with the following drawings in which like reference numerals refer to corresponding parts throughout the figures.  
       FIG. 1  is a schematic diagram illustrating an exemplary system for producing fibers with release-material sheaths.  
       FIG. 2  is a schematic diagram illustrating the system of  FIG. 1  with additional components for measuring fiber uniformity, cooling fiber in a controlled manner, and winding fiber onto a spool.  
       FIG. 3  is a schematic diagram illustrating the spin pack assembly in more detail.  
       FIG. 4  is a schematic diagram illustrating multi-purpose blocks  350 A &amp;  350 B and cutaway views of transfer/heating blocks  400 A &amp;  400 B in more detail.  
       FIG. 5  is a flow chart illustrating an exemplary process for producing fibers with release-material sheaths.  
       FIG. 6  is a schematic diagram illustrating exemplary fiber core cross sections, including (a) circular, (b) corrugated, (c) rectangular, (d) rectangular with rounded corners, and (e) racetrack oval. 
    
    
     DESCRIPTION OF EMBODIMENTS  
      This section describes fibers with release-material sheaths, methods and systems for making such fibers, papermaking belts incorporating such fibers, and papermaking processes using belts incorporating such fibers. Reference will be made to certain embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the embodiments, it will be understood that it is not intended to limit the invention to these particular embodiments alone. On the contrary, the invention is intended to cover alternatives, modifications and equivalents that are within the spirit and scope of the invention as defined by the appended claims.  
      Moreover, in the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these particular details. In other instances, methods, procedures, and components that are well-known to those of ordinary skill in the art are not described in detail to avoid obscuring aspects of the present invention.  
       FIG. 1  is a schematic diagram illustrating an exemplary system for producing fibers with release-material sheaths. The system in  FIG. 1  includes both “A” components that are used to extrude the core of the fiber and “B” components that are used to continuously extrude the release-material sheath around the core of the fiber. The A and B mechanical components are nearly the same in configuration, with the main difference being the size of the motor/extruder combination. This exemplary system includes: extruder drive assemblies  100 A &amp;  100 B, feed hopper/dryer systems  200 A &amp;  200 B, extruder screw/barrel assemblies  300 A &amp;  300 B, barrel heater bands  310 A &amp;  310 B, multi-purpose blocks  350 A &amp;  350 B, transfer/heating blocks  400 A &amp;  400 B, band heaters  410 A &amp;  410 B for transfer/heating blocks  400 A &amp;  400 B, pump/drive assemblies  500 A &amp;  500 B, pump heater bands  510 A &amp;  510 B, planetary gear pumps  520 A &amp;  520 B, flow distributors  600 A &amp;  600 B, and band heaters  610 A &amp;  610 B for flow distributors  600 A &amp;  600 B.  
       FIG. 2  is a schematic diagram illustrating the system of  FIG. 1  with additional components for measuring fiber uniformity, cooling fiber in a controlled manner, and winding fiber onto a spool. The additional components include: idler roll  1300 , individual product guide  1350 , segmented idler roll  1400 , quench unit stage  1   1100 , quench unit stage  2   1150 , quench unit stage  3   1000 , segmented drive roll  1200  (with independent controlling motors  1250 X for each segment in drive roll  1200 ), laser micrometer  1900 , and winding unit  2000 . Winding unit  2000  includes electrically driven high precision draw rolls  2100 , accumulator system  2200 , and traverse mechanism  2300  for fiber spool  2400 .  
      In some embodiments, quench unit stage  3   1000  is removed and quench unit stage  1   1100  and quench unit stage  2   1150  are lowered to be closer to spinneret face plate  700 . As shown in  FIG. 2 , in some embodiments, quench units  1000 ,  1100 , and  1150  are stacked on top of each other in the same orientation so that the air flows in the same direction in each quench unit (e.g., right to left in  FIG. 2 ). In other embodiments (not shown), the quench units are stacked in a staggered configuration so that the airflows are in opposite directions in adjacent quench units. For example, the airflow in quench unit stage  1   1100  is right-to-left and the airflow in quench unit stage  2   1150  is left-to-right (with quench unit stage  3   1000  removed). Opposing airflows can help maintain the shape of the fiber.  
      In some embodiments, each filament has its own winding unit  2000 , which allows for individual adjustment in filament speed. (For clarity, only one winding unit  2000  is shown in  FIG. 2 .) Multiple winding units  2000  and multiple spinneret inserts  800  allow for the formation of distinct fibers from each of the filament streams. Thus, if desired, a variety of fibers with different shapes and/or sizes can be run concurrently in the extrusion system by varying the spinneret insert(s)  800  and/or the winder  2000  settings. The winding unit accumulator system  2200  provides for continuous operation of the winder even during spool changes through the accumulation of fiber. The traverse mechanism  2300  controls the movement of spool  2400  and is electronically integrated to adjust take-up speed to uniformly wind fiber  1600  onto the spool as the diameter of the fiber accumulated on spool  2400  increases. Traverse mechanism  2300  moves fiber spool  2400  in and out during fiber  1600  uptake onto spool  2400 . Additional adjustments are provided for each of the fiber streams produced via the substitution of spinneret inserts  800 , e.g., varying the spinneret size and/or geometric shape.  
      It will be understood by those of ordinary skill in the art that additional flow distribution channels could be connected with additional extruders to produce multilayered fiber core and/or multilayered release-material sheaths.  
       FIG. 3  is a schematic diagram illustrating the spin pack assembly  950  in more detail. Spin pack assembly  950  is typically comprised of a number of sub-blocks, such as: multi-purpose blocks  350 A &amp;  350 B, transfer/heating blocks  400 A &amp;  400 B, filter block  535 , flow distributors  600 A &amp;  600 B, band heaters  610 A &amp;  610 B for flow distributors  600 A &amp;  600 B, spinneret face plate  700 , spinneret insert(s)  800 , spin face heater bands  825 , and filtration/polymer integration sub-assembly  850 . Filter block  535  contains polymer filters  525 . Polymer filters  525  remove any polymer gels present and also remove any potential charred polymer from the extrusion system. Exemplary filter cups are available through the Mott Filter Company (84 Spring Lane, Farmington, Conn. 06032) and are capable of removing particles that typically range from 10 to 100 microns in size. Spinneret insert(s)  800  provides for rapid replacement and changeover in spinneret shape(s) and spinneret size(s). As is well-known in the art, polymer integration sub-assembly  850  combines the molten core and sheath materials just prior to co-extrusion so that integrally formed (core+sheath) fiber structures can be produced (e.g., see U.S. Pat. No. 5,533,883, the disclosure of which is hereby incorporated by reference). Co-extrusion promotes adhesion between the core and the release-material sheath so that no primer is needed.  
       FIG. 4  is a schematic diagram illustrating multi-purpose blocks  350 A &amp;  350 B and cutaway views of transfer/heating blocks  400 A &amp;  400 B in more detail. Multi-purpose blocks  350 A &amp;  350 B include burst plugs  353 A &amp;  353 B (pressure safety valves), temperature probes  352 A &amp;  352 B, and pressure transducers  351 A &amp;  351 B. The design of blocks  350 A &amp;  350 B and  400 A &amp;  400 B minimizes resistance to polymer flow and provides feedback on processing parameters (e.g., temperature and pressure). Blocks  400 A &amp;  400 B can be split into two halves for easier cleaning. Transfer blocks  400 A &amp;  400 B also include breaker plates  360 A &amp;  360 B to improve the mixing of melted polymer.  FIG. 4  illustrates system components for both the core and the sheath, with each designated by an A or B, respectively. As noted above, it will be understood by those skilled in the art that spin pack assembly  950  could be connected with additional extruders to produce multilayered cores and/or multilayered sheaths.  
      The methods described herein can be applied to virtually all core materials and sheath release materials.  
      Exemplary core materials include, without limitation, polyester; nylon; polyphenylene sulphide; poly 1,4 cyclohexane dimethylene terephthalate; polyethylene naphthalate; polyetheretherketone; or combinations thereof.  
      As used in the specification and claims, a “release material” is a solid fluoropolymer [e.g., polytetrafluoroethylene (PTFE); fluorinated ethylene propylene (FEP) copolymers such as a tetrafluoroethylene hexafluoropropylene copolymer; perfluoroalkoxy (PFA) polymers; ethylene and tetrafluoroethylene (EFTE) copolymers; tetrafluoroethylene hexafluoropropylene vinylidene (THV) copolymers; and polyvinylidene difluoride] that facilitates the release of a paper web from a papermaking belt.  
       FIG. 5  is a flow chart illustrating an exemplary process for producing fibers with release-material sheaths. As noted above, the core and sheath extruders operate in an analogous manner, although they may be different in size.  
      At  5010 , pellets of clean and purified core and sheath polymer resins (polymeric starting materials, typically supplied by commercial resin manufacturers) are fed into feed hopper/dryer systems  200 A &amp;  200 B, respectively. Dryer systems  200 A &amp;  200 B continually dry the polymer resins using compressed air and a heating system. The temperature used in dryer systems  200 A is typically between 100 to 140° C., with 135° C. being preferred. Moisture is removed from the resins by operating dryer systems  200 A at a dew point of −40° C. Dryer system  200 B is not required to operate for all materials. Both dryer systems  200 A &amp;  200 B also have two coalescing filters in series to remove liquid water and oil droplet particles down to 0.01 micron in size. An exemplary dryer system  200  is a Novatect™ Compressed Air Dryer (Novatec, Inc. 222 E. Thomas Ave., Baltimore Md. 21225, www.novatec.com).  
      At  5020 , extruder drive assemblies  100 A &amp;  100 B feed the polymers into extruder screw/barrel assemblies  300 A &amp;  300 B, respectively, where the polymers are melted. Extruder drive assemblies  100 A &amp;  100 B are dedicated drive systems that maintain consistent operating RPMs to provide stable pressures during the continuous extrusion processes.  
      The gear ratios of the pulleys in extruder drive assemblies  100 A &amp;  100 B can be changed to enable the drive assembly motors to run at a preferred rate of 90-100% of the rated motor speed. A stable motor speed produces a stable screw speed, which, in turn, produces a consistent extrudate pressure. The measured pressure fluctuations are less than 2% during operation at various working pressures. Thus, the precision drives in extruder drive assemblies  100 A &amp;  100 B enable greater extruder control and feeding uniformity of the extrudates.  
      In some embodiments, extruder screw/barrel assemblies  300 A &amp;  300 B may be vented to remove volatile contaminants from the melted resins. In some embodiments, the polymers in the extruder assemblies may be blanketed with nitrogen (or inert gas) or subjected to vacuum in order to further reduce resin contamination and to improve the uniformity of the melts.  
      At  5030 , the feed screws in extruder screw/barrel assemblies  300 A &amp;  300 B move the melted core and sheath polymers through multipurpose blocks  350 A &amp;  350 B and transfer/heating blocks  400 A &amp;  400 B into planetary gear pumps  520 A &amp;  520 B, respectively, in a continuous, uniform manner. Planetary gear pumps  520 A &amp;  520 B are driven by dedicated drive assemblies  500 A &amp;  500 B, respectively. Pumps  520 A &amp;  520 B are single inlet pumps with multiple outlets. In some embodiments, the temperatures for the core and sheath polymers of the fiber are independently controlled and only come together as the fiber is being formed, thereby allowing for core and sheath polymers with different temperatures to be extruded simultaneously.  
      At  5040 , the melted core and sheath polymers move back into their respective transfer/heating blocks  400 A &amp;  400 B in a continuous, uniform manner. Pumps  520 A &amp;  520 B pressurize the molten polymers as they divide and distribute the flows into independent distribution channels in transfer blocks  400 A &amp;  400 B. For clarity,  FIG. 4  shows just one of the independent channels (i.e., channel  450 A) located within transfer/heating block  400 A. Similarly,  FIG. 4  shows just one of the independent channels (i.e., channel  450 B) located within transfer/heating block  400 B.  
      Channels  450 A and  450 B in blocks  400 A &amp;  400 B, respectively, permit high polymer flow rates with low restriction, thereby reducing shear heating (and concurrent temperature nonuniformities) in the polymer melts. The direction of polymer flow in spin pack assembly  950  can be changed in 90° increments. Thus, extrusion via spin pack assembly  950  can be vertically upward, vertically downward, or horizontal. Heating bands  610 A &amp;  610 B facilitate temperature control (and thus viscosity control) of the molten polymers while passing through spin pack assembly  950 .  
      At  5050 , the molten sheath material flows uniformly around the molten core material in polymer integration subassembly  850 , just before the molten core and sheath enter spinneret face plate  700 . Spinneret face plate  700  is equipped with spinneret inserts  800 . Spinneret inserts  800  enable rapid changeover in spinneret hole diameter, shape and the pin length-to-diameter ratio. The spin face heaters  825  control the temperature uniformity of the core and sheath extrudates as they exit the spinneret inserts  800  to form fiber  1600 .  
      At  5060 , the molten polymer core and sheath are co-extruded through spinneret face plate  700 . In some embodiments, forcing the molten polymer core through circular openings in spinneret insert(s)  800  forms a fiber core with substantially circular cross-sections. In other embodiments, forcing the molten polymer core through rectangular or other similarly shaped openings in spinneret insert(s)  800  forms a fiber core with substantially flat cross-sections.  FIG. 6  is a schematic diagram illustrating exemplary fiber core cross sections, including (a) circular, (b) corrugated, (c) rectangular, (d) rectangular with rounded comers, and (e) racetrack oval. The corrugation shown in  FIG. 6 ( b ) applied to a circular cross section can also be applied to other shapes, such as the shapes shown in FIGS.  6 ( c )- 6 ( e ). Co-extruding the molten polymer sheath that has flowed around the molten core material through openings in spinneret insert(s)  800  forms a sheath around the core. Spinneret insert(s)  800  may be changed to allow simultaneous production of different size and/or shaped fibers, thereby adding versatility to the production system.  
      In some embodiments, to increase the uniformity of the fiber cross sections, the extrusion in step  5060  is performed in a substantially vertical upward direction, against the force of gravity.  
      If vertically upward extrusion is used, at the start of the extrusion process, a metal rod or other inert surface makes contact with fiber  1600  exiting spinneret insert  800 , and lifts fiber  1600  up through individual product guide  1350 , then to idler roll  1300  and onto drive roll  1200 . Fiber  1600  is/are then passed over segmented idler roll  1400  and through the rest of the system in the same manner as is commonly done for horizontal or vertically downward extrusion processes. Each segment in idler roll  1400  can spin at a different speed if fiber streams with different dimensions are being extruded simultaneously. Alternatively, each segment in idler roll  1400  can spin at the same speed if fiber streams with the same dimensions are being extruded simultaneously.  
      At  5070 , fiber  1600  is cooled in a controlled manner. In some embodiments, fiber  1600  is cooled in a two- or three-stage cooling zone system.  
      In a two-stage cool with stage  3  quench unit  1000  removed, stage  1  quench unit  1100  is located adjacent to the spinneret face  700  and typically 3.5 inches away from fiber  1600  exiting spinneret insert(s)  800 . Stage  1  quench unit  1100  gradually cools fiber  1600  by blowing air over the fibers. Stage  1  quench unit  1100  is typically operated between 0 and 30° C., with 0° C. being preferred. Fans in stage  1  quench unit  1100  typically operate between 0 and 1750 RPM (corresponding to a measured air velocity of 0-493 feet per minute), with 1275 RPM (188 feet per minute) being preferred. Stage  2  quench unit  1150  typically operates at a temperature between 0 and 30° C., with 0° C. being preferred. Fans in stage  2  quench unit  1150  typically operate between 0 and 1750 RPM (corresponding to a measured air velocity of 0-573 feet per minute), with 1300 RPM (192 feet per minute) being preferred. Stage  2  quench unit  1150  is stacked in a staggered configuration with stage  1  quench unit  1100  so that the airflows in quench units  1100  and  1150  are in opposite directions. Stage  2  quench unit  1100  is positioned typically 2 inches away from the centerline of fiber  1600 . The staggered configuration allows for more uniform application of cool air to fiber  1600 , thereby producing more uniform cooling and preventing curling of the fiber. In some embodiments, the quench system is segmented into discrete chambers around each fiber filament stream to allow for individual control of air temperature and air speed around each individual fiber filament stream.  
      In some embodiments, stage  1   1100 , stage  2   1150  and stage  3   1000  quench units are stacked directly on top of one another. This embodiment is preferred for round fibers as the “curling” effect is less prevalent. This embodiment also can be segmented to allow for individual control of air temperature and airflow speed for each fiber. Tables 1-6 give exemplary process conditions for the co-extrusion of a fiber with a release-material sheath  1600 .  
               TABLE 1                       Exemplary process conditions for 500 micron diameter       polyester fiber (e.g., Dupont 5149 Polyester) with a       THV sheath (e.g., Dyneon THV 220G)                                                Temperature   Temperature           (° C.)   (° C.)       Component   for Core (A)   for Sheath (B)               screw/barrel assembly 300 zone 1   235   165       (zone nearest dryer 200)       screw/barrel assembly 300 zone 2   265   175       screw/barrel assembly 300 zone 3   275   185       screw/barrel assembly 300 zone 4   280   200       screw/barrel assembly 300 zone 5   280   240       (zone nearest block 350)       planetary gear pump 520 inlet   283   228       planetary gear pump 520 block   271   194       planetary gear pump 520 outlet   290   251       pump heater band 510   280   240       band heater 410   281   250       band heater(s) 610   281/291/279   260/260/250       plate 700 inlet   285   267       spin face heater band 825   250   250               Component   Core (A)   Sheath (B)               Screw/barrel assembly 300 pressure   1200   2000       set point (PSI)       Planetary gear pump 520 outlet   749   1495       pressure (PSI)       Planetary gear pump 520 speed   3.26   13       (RPM)                 Fiber was produced at 8.5 meters per minute. Tensile strength was 8.60 kgf.             
 
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
               
               
                 Exemplary process conditions for 350 micron diameter 
               
               
                 polyester fiber (e.g., Dupont 5149 Polyester) with a 
               
               
                 THV sheath (e.g., Dyneon THV 220G) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Temperature 
                 Temperature 
               
               
                   
                 (° C.) 
                 (° C.) 
               
               
                 Component 
                 for Core (A) 
                 for Sheath (B) 
               
               
                   
               
               
                 screw/barrel assembly 300 zone 1 
                 235 
                 165 
               
               
                 (zone nearest dryer 200) 
               
               
                 screw/barrel assembly 300 zone 2 
                 265 
                 175 
               
               
                 screw/barrel assembly 300 zone 3 
                 275 
                 185 
               
               
                 screw/barrel assembly 300 zone 4 
                 280 
                 200 
               
               
                 screw/barrel assembly 300 zone 5 
                 280 
                 240 
               
               
                 (zone nearest block 350) 
               
               
                 planetary gear pump 520 inlet 
                 282 
                 230 
               
               
                 planetary gear pump 520 block 
                 271 
                 191 
               
               
                 planetary gear pump 520 outlet 
                 290 
                 252 
               
               
                 pump heater band 510 
                 280 
                 240 
               
               
                 band heater 410 
                 281 
                 260 
               
               
                 band heater(s) 610 
                 285/291/279 
                 267/260/250 
               
               
                 plate 700 inlet 
                 285 
                 267 
               
               
                 spin face heater band 825 
                 250 
                 250 
               
               
                   
               
               
                 Component 
                 Core (A) 
                 Sheath (B) 
               
               
                   
               
               
                 Screw/barrel assembly 300 pressure 
                 1200 
                 2000 
               
               
                 set point (PSI) 
               
               
                 Planetary gear pump 520 outlet 
                 827 
                 1187 
               
               
                 pressure (PSI) 
               
               
                 Planetary gear pump 520 speed 
                 3.56 
                 10 
               
               
                 (RPM) 
               
               
                   
               
               
                   Fiber was produced at 14.6 meters per minute. Tensile strength was 6.00 kgf.    
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
               
                   
               
               
                 Exemplary process conditions for 500 micron diameter 
               
               
                 polyester fiber (e.g., Dupont 5149 Polyester) with a 
               
               
                 THV sheath (e.g., Dyneon THV 815G) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Temperature 
                 Temperature 
               
               
                   
                 (° C.) 
                 (° C.) 
               
               
                 Component 
                 for Core (A) 
                 for Sheath (B) 
               
               
                   
               
               
                 screw/barrel assembly 300 zone 1 
                 235 
                 275 
               
               
                 (zone nearest dryer 200) 
               
               
                 screw/barrel assembly 300 zone 2 
                 265 
                 285 
               
               
                 screw/barrel assembly 300 zone 3 
                 280 
                 285 
               
               
                 screw/barrel assembly 300 zone 4 
                 285 
                 285 
               
               
                 screw/barrel assembly 300 zone 5 
                 285 
                 285 
               
               
                 (zone nearest block 350) 
               
               
                 planetary gear pump 520 inlet 
                 288 
                 284 
               
               
                 planetary gear pump 520 block 
                 276 
                 283 
               
               
                 planetary gear pump 520 outlet 
                 294 
                 299 
               
               
                 pump heater band 510 
                 282 
                 292 
               
               
                 band heater 410 
                 285 
                 280 
               
               
                 band heater(s) 610 
                 285/285/282 
                 290/290/280 
               
               
                 plate 700 inlet 
                 290 
                 290 
               
               
                 spin face heater band 825 
                 296 
                 296 
               
               
                   
               
               
                 Component 
                 Core (A) 
                 Sheath (B) 
               
               
                   
               
               
                 Screw/barrel assembly 300 pressure 
                 1200 
                 2250 
               
               
                 set point (PSI) 
               
               
                 Planetary gear pump 520 outlet 
                 367 
                 1467 
               
               
                 pressure (PSI) 
               
               
                 Planetary gear pump 520 speed 
                 3.40 
                 13 
               
               
                 (RPM) 
               
               
                   
               
               
                   Fiber was produced at 8.4 meters per minute. Tensile strength was 9.44 kgf.    
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
               
                   
               
               
                 Exemplary process conditions for 350 micron diameter 
               
               
                 polyester fiber (e.g., Dupont 5149 Polyester) with a 
               
               
                 THV sheath (e.g., Dyneon THV 815G) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Temperature 
                 Temperature 
               
               
                   
                 (° C.) 
                 (° C.) 
               
               
                 Component 
                 for Core (A) 
                 for Sheath (B) 
               
               
                   
               
               
                 screw/barrel assembly 300 zone 1 
                 235 
                 275 
               
               
                 (zone nearest dryer 200) 
               
               
                 screw/barrel assembly 300 zone 2 
                 265 
                 285 
               
               
                 screw/barrel assembly 300 zone 3 
                 280 
                 285 
               
               
                 screw/barrel assembly 300 zone 4 
                 285 
                 285 
               
               
                 screw/barrel assembly 300 zone 5 
                 285 
                 285 
               
               
                 (zone nearest block 350) 
               
               
                 planetary gear pump 520 inlet 
                 287 
                 284 
               
               
                 planetary gear pump 520 block 
                 275 
                 282 
               
               
                 planetary gear pump 520 outlet 
                 292 
                 299 
               
               
                 pump heater band 510 
                 282 
                 290 
               
               
                 band heater 410 
                 285 
                 280 
               
               
                 band heater(s) 610 
                 285/285/282 
                 285/290/290 
               
               
                 plate 700 inlet 
                 282 
                 283 
               
               
                 spin face heater band 825 
                 297 
                 297 
               
               
                   
               
               
                 Component 
                 Core (A) 
                 Sheath (B) 
               
               
                   
               
               
                 Screw/barrel assembly 300 pressure 
                 1200 
                 1750 
               
               
                 set point (PSI) 
               
               
                 Planetary gear pump 520 outlet 
                 469 
                 1638 
               
               
                 pressure (PSI) 
               
               
                 Planetary gear pump 520 speed 
                 3.39 
                 13 
               
               
                 (RPM) 
               
               
                   
               
               
                   Fiber was produced at 14.2 meters per minute. Tensile strength was 5.84 kgf.    
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 5 
               
               
                   
               
               
                   
               
               
                 Exemplary process conditions for 500 micron diameter 
               
               
                 polyester fiber (e.g., Dupont 5147 Polyester) with a 
               
               
                 THV sheath (e.g., Dyneon THV 220G) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Temperature 
                 Temperature 
               
               
                   
                 (° C.) 
                 (° C.) 
               
               
                 Component 
                 for Core (A) 
                 for Sheath (B) 
               
               
                   
               
               
                 screw/barrel assembly 300 zone 1 
                 235 
                 165 
               
               
                 (zone nearest dryer 200) 
               
               
                 screw/barrel assembly 300 zone 2 
                 265 
                 175 
               
               
                 screw/barrel assembly 300 zone 3 
                 275 
                 185 
               
               
                 screw/barrel assembly 300 zone 4 
                 295 
                 200 
               
               
                 screw/barrel assembly 300 zone 5 
                 290 
                 240 
               
               
                 (zone nearest block 350) 
               
               
                 planetary gear pump 520 inlet 
                 267 
                 225 
               
               
                 planetary gear pump 520 block 
                 279 
                 192 
               
               
                 planetary gear pump 520 outlet 
                 299 
                 255 
               
               
                 pump heater band 510 
                 285 
                 233 
               
               
                 band heater 410 
                 290 
                 240 
               
               
                 band heater(s) 610 
                 286/286/280 
                 260/260/250 
               
               
                 plate 700 inlet 
                 285 
                 261 
               
               
                 spin face heater band 825 
                 252 
                 252 
               
               
                   
               
               
                 Component 
                 Core (A) 
                 Sheath (B) 
               
               
                   
               
               
                 Screw/barrel assembly 300 pressure 
                 400 
                 1400 
               
               
                 set point (PSI) 
               
               
                 Planetary gear pump 520 outlet 
                 171 
                 1229 
               
               
                 pressure (PSI) 
               
               
                 Planetary gear pump 520 speed 
                 7.5 
                 17 
               
               
                 (RPM) 
               
               
                   
               
               
                   Fiber was produced at 7.3 meters per minute. Tensile strength was 9.83 kgf.    
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 6 
               
               
                   
               
               
                   
               
               
                 Exemplary process conditions for 350 micron diameter 
               
               
                 polyester fiber (e.g., Dupont 5149 Polyester) with a 
               
               
                 FEP sheath (e.g., Dupont FEP 100) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Temperature 
                 Temperature 
               
               
                   
                 (° C.) 
                 (° C.) 
               
               
                 Component 
                 for Core (A) 
                 for Sheath (B) 
               
               
                   
               
               
                 screw/barrel assembly 300 zone 1 
                 255 
                 310 
               
               
                 (zone nearest dryer 200) 
               
               
                 screw/barrel assembly 300 zone 2 
                 285 
                 380 
               
               
                 screw/barrel assembly 300 zone 3 
                 287 
                 385 
               
               
                 screw/barrel assembly 300 zone 4 
                 285 
                 380 
               
               
                 screw/barrel assembly 300 zone 5 
                 285 
                 380 
               
               
                 (zone nearest block 350) 
               
               
                 planetary gear pump 520 inlet 
                 275 
                 388 
               
               
                 planetary gear pump 520 block 
                 277 
                 372 
               
               
                 planetary gear pump 520 outlet 
                 294 
                 400 
               
               
                 pump heater band 510 
                 282 
                 368 
               
               
                 band heater 410 
                 285 
                 376 
               
               
                 band heater(s) 610 
                 285/285/282 
                 364/364/322 
               
               
                 plate 700 inlet 
                 293 
                 322 
               
               
                 spin face heater band 825 
                 359 
                 359 
               
               
                   
               
               
                 Component 
                 Core (A) 
                 Sheath (B) 
               
               
                   
               
               
                 Screw/barrel assembly 300 pressure 
                 1000 
                 2750 
               
               
                 set point (PSI) 
               
               
                 Planetary gear pump 520 outlet 
                 340 
                 2822 
               
               
                 pressure (PSI) 
               
               
                 Planetary gear pump 520 speed 
                 1.4 
                 15 
               
               
                 (RPM) 
               
               
                   
               
               
                   Fiber was produced at 8.3 meters per minute. Tensile strength was 8.60 kgf.    
               
            
           
         
       
     
      At  5080 , the uniformity of the fiber cross section is measured. In some embodiments, the measurement is done using laser micrometer  1900 . An exemplary laser micrometer  1900  is a Beta LaserMike diameter gauge (Beta LaserMike, 8001 Technology Blvd., Dayton, Ohio 45424, www.betalasermike.com). In some embodiments, to increase the uniformity of the fiber cross section, laser micrometer  1900  can be part of an on-line automatic feedback control system. An automatic feedback system integrated with laser micrometer  1900  can send information used to control a servo-motor system for each fiber filament, thereby controlling size and operation independently for each fiber filament.  
      As shown in  FIG. 2 , at  5090 , fiber  1600  is fed to S wrap system  2100  in winding unit  2000  and wound onto fiber spool  2400 .  
      In addition to the steps described above, after extrusion, fiber  1600  can be drawn (i.e., stretched) by a variety of different methods, including without limitation: (1) spin drawing; (2) spin drawing plus solid-state drawing; and (3) continuous incremental drawing.  
      In spin drawing, fiber  1600  are drawn immediately after co-extrusion and wound onto a spool. This drawing method typically provides excellent sheath uniformity with no phase separation between the sheath and the core. This drawing method typically produces fiber with low molecular orientation and moderate strength.  
      In spin drawing plus solid-state drawing, fiber  1600  is drawn immediately after co-extrusion and wound onto a spool. Fiber  1600  is then unwound from the spool in a secondary process and drawn in the solid state with a large draw ratio. This drawing method typically produces highly oriented fiber with high strength and excellent sheath uniformity. However, phase separation between the core and sheath during the solid-state drawing step may produce defects in fiber  1600 .  
      In continuous incremental drawing, co-extruded fiber  1600  is continuously drawn by increasing the linear speed of each roll that fiber  1600  passes over. For example, the linear speed of a second roll will be greater than the linear speed of a first roll, thereby drawing the fiber between the second roll and the first roll. This incremental drawing process can be repeated between additional rolls and under different drawing temperatures. This drawing procedure results in a large draw ratio and high molecular orientation without a separate solid-state drawing step. This drawing method typically produces high strength fiber with excellent physical and environmental stability, excellent cross section uniformity, and no phase separation between the sheath and core of fiber  1600 .  
      Fiber  1600  with a wide range of dimensions can be manufactured. Table 7 presents exemplary dimensional data for 350 micron and 500 micron diameter fibers. In some cases, the standard deviation in fiber cross-section diameter is less than 2 percent of the average fiber cross-section diameter. In some cases, the standard deviation in fiber cross-section diameter is less than 0.5 percent of the average fiber cross-section diameter. The uniformity of the fiber core cross section is essentially the same as the uniformity of the entire (core+sheath) cross section because the sheath thickness is much less than the core thickness. The sheath thickness was typically 10 microns, although greater thicknesses can be used (e.g., to ensure that some release material remains if belts made from the fibers are sanded).  
               TABLE 7                          Exemplary dimensional data                         Nominal fiber dimensions   Actual Size   Roundness       (microns)   (microns)   (microns)               350   Fiber 1 Avg: 349.3   Fiber 1 Avg: 3.9       (core w/ sheath)   StdDev: 3.2   StdDev: 1.1       Core: Polyester   Fiber 2 Avg: 351.4   Fiber 2 Avg: 2.3       (e.g., Dupont 5149 Polyester)   StdDev: 4.5   StdDev: 1.2       Sheath: THV   Fiber 3 Avg: 351.1   Fiber 3 Avg: 3.2       (e.g., Dyneon THV 815G)   StdDev: 3.8   StdDev: 1.1           Fiber 4 Avg. 352.1   Fiber 4 Avg. 4.6           StdDev: 3.6   StdDev: 1.3           N = 5731 Samples   N = 5731 Samples       500   Fiber 1 Avg: 499.1   Fiber 1 Avg: 4.2       (core w/ sheath)   StdDev: 1.8   StdDev: 0.9       Core: Polyester   Fiber 2 Avg: 500.3   Fiber 2 Avg: 3.3       (e.g., Dupont 5149 Polyester)   StdDev: 1.8   StdDev: 1.3       Sheath: THV   Fiber 3 Avg: 499.4   Fiber 3 Avg: 3.3       (e.g., Dyneon THV 815G)   StdDev: 2.4   StdDev: 1.6           Fiber 4 Avg. 500.1   Fiber 4 Avg. 3.4           StdDev: 2.3   StdDev: 1.6           N = 2355 Samples   N = 5731 Samples       350   Fiber 1 Avg: 358.5   Fiber 1 Avg: 11.8       (core w/ sheath)   StdDev: 26.5   StdDev: 6.0       Core: Polyester   N = 93 Samples   N = 93 Samples       (e.g., Dupont 5149 Polyester)       Sheath: FEP       (e.g., Dupont FEP 100)                  
 
      A plurality of fibers can be intermeshed to form a papermaking fabric (belt). The intermeshing can be done in a wide variety of ways that are well known in the art, including by weaving, knitting, or coiling. Examples of these methods are described in U.S. Pat. Nos. 6,352,772; 6,174,825; 5,776,313; and 4,239,065, the disclosures of which are hereby incorporated by reference. In some embodiments, the paper making belt made from the fibers also includes a temporary release material applied to the mesh of fibers.  
      The papermaking belt can be used to carry a fibrous web in at least one part of a papermaking process. The papermaking can be done in a wide variety of ways that are well known in the art. Examples of papermaking methods are described in U.S. Pat. Nos. 6,514,382; 6,248,212; 6,139,686; 3,994,771; and 3,825,381, the disclosures of which are hereby incorporated by reference.  
      The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.