U.S. patent application number 11/265706 was filed with the patent office on 2007-05-03 for fiber with release-material sheath for papermaking belts.
Invention is credited to Pierluigi Cappellini, Kambiz Damaghi, James F. II Peterson.
Application Number | 20070098984 11/265706 |
Document ID | / |
Family ID | 37996741 |
Filed Date | 2007-05-03 |
United States Patent
Application |
20070098984 |
Kind Code |
A1 |
Peterson; James F. II ; et
al. |
May 3, 2007 |
Fiber with release-material sheath for papermaking belts
Abstract
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 are
described.
Inventors: |
Peterson; James F. II;
(State College, PA) ; Cappellini; Pierluigi;
(Jersey Shore, PA) ; Damaghi; Kambiz; (Great Neck,
NY) |
Correspondence
Address: |
MORGAN, LEWIS & BOCKIUS, LLP.
2 PALO ALTO SQUARE
3000 EL CAMINO REAL
PALO ALTO
CA
94306
US
|
Family ID: |
37996741 |
Appl. No.: |
11/265706 |
Filed: |
November 1, 2005 |
Current U.S.
Class: |
428/375 |
Current CPC
Class: |
D01F 8/04 20130101; D21F
1/0027 20130101; Y10T 428/2933 20150115 |
Class at
Publication: |
428/375 |
International
Class: |
D02G 3/00 20060101
D02G003/00 |
Claims
1. A fiber for use in a papermaking belt, comprising: an inner core
and an outer sheath that are integrally formed, wherein the outer
sheath: has a thickness of at least 10 microns prior to sanding, if
any, of the fiber, and includes a release material with a melting
temperature greater than the melting temperature of the inner core
to facilitate the release of a paper web when the paper web is in
contact with the fiber.
2. A fiber for use in a papermaking belt, comprising: an inner core
and an outer sheath, wherein 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.
3. The fiber of claim 2, wherein the core and the outer sheath are
integrally formed.
4. The fiber of claim 3, wherein the core and the outer sheath are
formed by co-extrusion.
5. The fiber of claim 2, wherein the thickness of the outer sheath
is sufficient to allow sanding of the fiber without reaching the
inner core.
6. The fiber of claim 2, wherein the release material has a melting
temperature greater than the melting temperature of the inner
core.
7. The fiber of claim 2, wherein the standard deviation in fiber
cross-section diameter is less than 2 percent of the average fiber
cross-section diameter.
8. The fiber of claim 2, wherein the standard deviation in fiber
cross-section diameter is less than 0.5 percent of the average
fiber cross-section diameter.
9. A method of making a fiber, comprising forming a fiber core, and
forming an outer sheath around the fiber core, wherein 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.
10. The method of claim 9, wherein the core and the sheath are
integrally formed.
11. The method of claim 9, wherein the core and the sheath are
formed by coextrusion.
12. The method of claim 9, wherein there is no primer between the
core and the sheath.
13. A paper making belt, comprising: a mesh of fibers, wherein at
least some of the fibers include an outer sheath integrally formed
around an inner core, wherein 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.
14. The paper making belt of claim 13, further including a
temporary release material applied to the mesh of fibers.
15. A method, comprising: intermeshing a plurality of fibers to
form a papermaking belt, wherein at least some fibers in the
plurality of fibers include an outer sheath integrally formed
around an inner core, wherein 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.
16. The method of claim 15, wherein the intermeshing is done by
weaving, knitting, or coiling.
17. A method, comprising: using a papermaking belt to carry a
fibrous web in at least one part of a papermaking process, wherein
the belt comprises a mesh of fibers, wherein at least some of the
fibers include an outer sheath integrally formed around an inner
core, wherein 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.
Description
FIELD OF INVENTION
[0001] 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
[0002] 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).
[0003] 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.
[0004] 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."
[0005] 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.
[0006] 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."
[0007] 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.
[0008] 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.sup.2
fabric)."
[0009] 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.sup.2
corresponds to 150-500 Angstroms for a material with a density of 2
gm/cm.sup.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.
[0010] Thus, there remains a need for improved papermaking belts
with better durability and release properties.
SUMMARY
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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
[0017] 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.
[0018] FIG. 1 is a schematic diagram illustrating an exemplary
system for producing fibers with release-material sheaths.
[0019] 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.
[0020] FIG. 3 is a schematic diagram illustrating the spin pack
assembly in more detail.
[0021] FIG. 4 is a schematic diagram illustrating multi-purpose
blocks 350A & 350B and cutaway views of transfer/heating blocks
400A & 400B in more detail.
[0022] FIG. 5 is a flow chart illustrating an exemplary process for
producing fibers with release-material sheaths.
[0023] 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
[0024] 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.
[0025] 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.
[0026] 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 100A & 100B, feed hopper/dryer
systems 200A & 200B, extruder screw/barrel assemblies 300A
& 300B, barrel heater bands 310A & 310B, multi-purpose
blocks 350A & 350B, transfer/heating blocks 400A & 400B,
band heaters 410A & 410B for transfer/heating blocks 400A &
400B, pump/drive assemblies 500A & 500B, pump heater bands 510A
& 510B, planetary gear pumps 520A & 520B, flow distributors
600A & 600B, and band heaters 610A & 610B for flow
distributors 600A & 600B.
[0027] 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 1250X 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.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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
350A & 350B, transfer/heating blocks 400A & 400B, filter
block 535, flow distributors 600A & 600B, band heaters 610A
& 610B for flow distributors 600A & 600B, 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.
[0032] FIG. 4 is a schematic diagram illustrating multi-purpose
blocks 350A & 350B and cutaway views of transfer/heating blocks
400A & 400B in more detail. Multi-purpose blocks 350A &
350B include burst plugs 353A & 353B (pressure safety valves),
temperature probes 352A & 352B, and pressure transducers 351A
& 351B. The design of blocks 350A & 350B and 400A &
400B minimizes resistance to polymer flow and provides feedback on
processing parameters (e.g., temperature and pressure). Blocks 400A
& 400B can be split into two halves for easier cleaning.
Transfer blocks 400A & 400B also include breaker plates 360A
& 360B 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.
[0033] The methods described herein can be applied to virtually all
core materials and sheath release materials.
[0034] Exemplary core materials include, without limitation,
polyester; nylon; polyphenylene sulphide; poly 1,4 cyclohexane
dimethylene terephthalate; polyethylene naphthalate;
polyetheretherketone; or combinations thereof.
[0035] 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.
[0036] 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.
[0037] 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 200A & 200B, respectively. Dryer systems 200A &
200B continually dry the polymer resins using compressed air and a
heating system. The temperature used in dryer systems 200A is
typically between 100 to 140.degree. C., with 135.degree. C. being
preferred. Moisture is removed from the resins by operating dryer
systems 200A at a dew point of -40.degree. C. Dryer system 200B is
not required to operate for all materials. Both dryer systems 200A
& 200B 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.TM. Compressed Air
Dryer (Novatec, Inc. 222 E. Thomas Ave., Baltimore Md. 21225,
www.novatec.com).
[0038] At 5020, extruder drive assemblies 100A & 100B feed the
polymers into extruder screw/barrel assemblies 300A & 300B,
respectively, where the polymers are melted. Extruder drive
assemblies 100A & 100B are dedicated drive systems that
maintain consistent operating RPMs to provide stable pressures
during the continuous extrusion processes.
[0039] The gear ratios of the pulleys in extruder drive assemblies
100A & 100B 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
100A & 100B enable greater extruder control and feeding
uniformity of the extrudates.
[0040] In some embodiments, extruder screw/barrel assemblies 300A
& 300B 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.
[0041] At 5030, the feed screws in extruder screw/barrel assemblies
300A & 300B move the melted core and sheath polymers through
multipurpose blocks 350A & 350B and transfer/heating blocks
400A & 400B into planetary gear pumps 520A & 520B,
respectively, in a continuous, uniform manner. Planetary gear pumps
520A & 520B are driven by dedicated drive assemblies 500A &
500B, respectively. Pumps 520A & 520B 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.
[0042] At 5040, the melted core and sheath polymers move back into
their respective transfer/heating blocks 400A & 400B in a
continuous, uniform manner. Pumps 520A & 520B pressurize the
molten polymers as they divide and distribute the flows into
independent distribution channels in transfer blocks 400A &
400B. For clarity, FIG. 4 shows just one of the independent
channels (i.e., channel 450A) located within transfer/heating block
400A. Similarly, FIG. 4 shows just one of the independent channels
(i.e., channel 450B) located within transfer/heating block
400B.
[0043] Channels 450A and 450B in blocks 400A & 400B,
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.degree.
increments. Thus, extrusion via spin pack assembly 950 can be
vertically upward, vertically downward, or horizontal. Heating
bands 610A & 610B facilitate temperature control (and thus
viscosity control) of the molten polymers while passing through
spin pack assembly 950.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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.degree. C., with 0.degree. 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.degree. C., with 0.degree. 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.
[0050] 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-US-00001 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 (.degree.
C.) (.degree. 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.
[0051] TABLE-US-00002 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
(.degree. C.) (.degree. 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.
[0052] TABLE-US-00003 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
(.degree. C.) (.degree. 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.
[0053] TABLE-US-00004 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
(.degree. C.) (.degree. 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.
[0054] TABLE-US-00005 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
(.degree. C.) (.degree. 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.
[0055] TABLE-US-00006 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
(.degree. C.) (.degree. 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.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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-US-00007 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)
[0063] 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.
[0064] 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.
[0065] 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.
* * * * *
References