U.S. patent application number 13/371872 was filed with the patent office on 2013-08-15 for structured fabric for use in a papermaking machine and the fibrous web produced thereon.
The applicant listed for this patent is Scott Quigley. Invention is credited to Scott Quigley.
Application Number | 20130206348 13/371872 |
Document ID | / |
Family ID | 47720501 |
Filed Date | 2013-08-15 |
United States Patent
Application |
20130206348 |
Kind Code |
A1 |
Quigley; Scott |
August 15, 2013 |
STRUCTURED FABRIC FOR USE IN A PAPERMAKING MACHINE AND THE FIBROUS
WEB PRODUCED THEREON
Abstract
A papermaking machine for the production of a fibrous web. The
papermaking machine including a plurality of rollers and a
structured fabric moving along the plurality of rollers. The
structured fabric includes a plurality of weft yarns and a
plurality of warp yarns woven with the plurality of weft yarns to
produce a weave pattern. The plurality of warp yarns being a
plurality of paired warp yarn sets. Each paired warp yarn set
including a first warp yarn and a second warp yarn, within the
weave pattern the first warp yarn forms a float over at least three
weft yarns and weaves with a single weft yarn immediately adjacent
to the float. The second warp yarn having a reverse pattern to the
first warp yarn. The float of the first warp yarn having a start
that is at the same position as a finish of the float of the second
warp yarn.
Inventors: |
Quigley; Scott; (Bossier
City, LA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Quigley; Scott |
Bossier City |
LA |
US |
|
|
Family ID: |
47720501 |
Appl. No.: |
13/371872 |
Filed: |
February 13, 2012 |
Current U.S.
Class: |
162/116 ;
162/358.2 |
Current CPC
Class: |
D21F 11/006 20130101;
D21F 9/00 20130101; D21F 11/14 20130101; D21F 1/0027 20130101 |
Class at
Publication: |
162/116 ;
162/358.2 |
International
Class: |
D21H 27/02 20060101
D21H027/02; D21F 3/00 20060101 D21F003/00 |
Claims
1. A papermaking machine for the production of a fibrous web, the
papermaking machine, comprising: a plurality of rollers; and a
structured fabric moving along said plurality of rollers, said
structured fabric including: a plurality of weft yarns; and a
plurality of warp yarns woven with said plurality of weft yarns to
produce a weave pattern, said plurality of warp yarns being a
plurality of paired warp yarn sets, each paired warp yarn set
including a first warp yarn and a second warp yarn, within said
weave pattern said first warp yarn forming a float over at least
three weft yarns and weaving with a single weft yarn immediately
adjacent to said float, said second warp yarn having a reverse
pattern to said first warp yarn, said float of said first warp yarn
having a start that is at the same position as a finish of said
float of said second warp yarn.
2. The papermaking machine of claim 1, wherein said yarn weave of
said plurality of warp yarns of said structured fabric additionally
has a weave with two of said weft yarns adjacent to said float.
3. The papermaking machine of claim 2, wherein said weave pattern
is repeated every ten warp yarns and every ten weft yarns.
4. The papermaking machine of claim 3, wherein said yarn weave is
repeating sequentially going over three weft yarns in said float,
under one weft yarn, over the next weft yarn, under the next two
weft yarns, over the next one weft yarn, then under the next two
weft yarns.
5. The papermaking machine of claim 1, wherein each said warp yarn
has a cross-sectional dimension of between approximately 0.10 mm
and approximately 1.0 mm.
6. The papermaking machine of claim 1, wherein the papermaking
machine is one of a TAD system, an ATMOS system, an E-TAD system,
and a Metso system.
7. The papermaking machine of claim 1, wherein at least one of said
plurality of warp yarns of said weave pattern have a polygonal
cross-section.
8. The papermaking machine of claim 1, wherein said weave pattern
results in pockets, said pockets having a quantity that is between
approximately 50/in.sup.2 and approximately 500/in.sup.2.
9. A structured fabric for use with a papermaking machine for the
production of a fibrous web, the structured fabric, comprising: a
plurality of weft yarns; and a plurality of warp yarns woven with
said plurality of weft yarns to produce a weave pattern, said
plurality of warp yarns being a plurality of paired warp yarn sets,
each paired warp yarn set including a first warp yarn and a second
warp yarn, within said weave pattern said first warp yarn forming a
float over at least three weft yarns and weaving with a single weft
yarn immediately adjacent to said float, said second warp yarn
having a reverse pattern to said first warp yarn, said float of
said first warp yarn having a start that is at the same position as
a finish of said float of said second warp yarn.
10. The structured fabric of claim 9, wherein said yarn weave of
said plurality of warp yarns additionally has a weave with two of
said weft yarns adjacent to said float.
11. The structured fabric of claim 10, wherein said weave pattern
is repeated every ten warp yarns and every ten weft yarns.
12. The structured fabric of claim 11, wherein said yarn weave is
repeating sequentially going over three weft yarns in said float,
under one weft yarn, over the next weft yarn, under the next two
weft yarns, over the next one weft yarn, then under the next two
weft yarns.
13. The structured fabric of claim 9, wherein said warp yarns have
a diameter of between approximately 0.10 mm and approximately 1.0
mm.
14. The structured fabric of claim 9, wherein the papermaking
machine is one of a TAD system, an ATMOS system, an E-TAD system,
and a Metso system.
15. The structured fabric of claim 9, wherein at least one of said
plurality of warp yarns of said weave pattern have a polygonal
cross-section.
16. The structured fabric of claim 9, wherein said weave pattern
results in pockets, said pockets having a quantity that is between
approximately 50/in.sup.2 and approximately 500/in.sup.2.
17. A fibrous web, comprising: a fibrous construct having at least
one formed surface feature, said surface feature including a
topographical pattern reflective of a weave pattern in a fabric
used in a papermaking machine, the fabric including: a plurality of
weft yarns; and a plurality of warp yarns woven with said plurality
of weft yarns to produce a weave pattern, said plurality of warp
yarns being a plurality of paired warp yarn sets, each paired warp
yarn set including a first warp yarn and a second warp yarn, within
said weave pattern said first warp yarn forming a float over at
least three weft yarns and weaving with a single weft yarn
immediately adjacent to said float, said second warp yarn having a
reverse pattern to said first warp yarn, said float of said first
warp yarn having a start that is at the same position as a finish
of said float of said second warp yarn.
18. The fibrous web of claim 17, wherein said yarn weave of said
plurality of warp yarns additionally has a weave with two of said
weft yarns adjacent to said float.
19. The fibrous web of claim 18, wherein said weave pattern is
repeated every ten warp yarns and every ten weft yarns.
20. The fibrous web of claim 19, wherein the fibrous web has at
least one, preferably all of the following properties: a basis
weight in the range of 17-19.5 gram/m.sup.2; a caliper of 0.45 to
0.49 mm; a bulk of 22 to 27 cm.sup.3/gram; and an absorbency of
15-18 gram of water/gram of paper.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to papermaking, and
relates more specifically to a structured fabric employed in a
papermaking machine for the production of a fibrous web and the
fibrous web manufactured thereby, the fibrous web being tissue or
toweling.
[0003] 2. Description of the related art.
[0004] In a conventional papermaking process, a water slurry, or
suspension, of cellulosic fibers (known as the paper "stock") is
fed into a gap between two endless woven wires that travels between
two or more rolls. At least one of the wires are often referred to
as a "structured fabric" that provides a papermaking surface on the
upper surface of its upper run which operates as a filter to
separate the cellulosic fibers of the paper stock from the aqueous
medium, thereby forming a wet paper web. The aqueous medium drains
through mesh openings of the structured fabric, known as drainage
holes, by gravity or vacuum located on the lower surface of the
upper run (i.e., the "machine side") of the fabric.
[0005] After leaving the forming section, the paper web is
transferred to a press section of the paper machine, where it is
passed through the nips of one or more pairs of pressure rollers
covered with another fabric, typically referred to as a "press
felt." Pressure from the rollers removes additional moisture from
the web; the moisture removal is often enhanced by the presence of
a "batt" layer of the press felt. The paper is then transferred to
a dryer section for further moisture removal. After drying, the
paper is ready for secondary processing and packaging.
[0006] Typically, papermakers' fabrics are manufactured as endless
belts by one of two basic weaving techniques. In the first of these
techniques, fabrics are flat woven by a flat weaving process, with
their ends being joined to form an endless belt by any one of a
number of well-known joining methods, such as dismantling and
reweaving the ends together (commonly known as splicing), or sewing
on a pin-seamable flap or a special foldback on each end, then
reweaving these into pin-seamable loops. A number of auto-joining
machines are available, which for certain fabrics may be used to
automate at least part of the joining process. In a flat woven
papermakers' fabric, the warp yarns extend in the machine direction
and the filling or weft yarns extend in the cross machine
direction.
[0007] In the second basic weaving technique, fabrics are woven
directly in the form of a continuous belt with an endless weaving
process. In the endless weaving process, the warp yarns extend in
the cross machine direction and the filling yarns extend in the
machine direction. Both weaving methods described hereinabove are
well known in the art, and the term "endless belt" as used herein
refers to belts made by either method.
[0008] Effective sheet and fiber support are important
considerations in papermaking, especially for the forming section
of the papermaking machine, where the wet web is initially formed.
Additionally, the structured fabrics should exhibit good stability
when they are run at high speeds on the papermaking machines, and
preferably are highly permeable to reduce the amount of water
retained in the web when it is transferred to the press section of
the paper machine. In both tissue and fine paper applications
(i.e., paper for use in quality printing, carbonizing, cigarettes,
electrical condensers, and the like) the papermaking surface
comprises a very finely woven or fine wire mesh structure.
[0009] In a conventional tissue forming machine, the sheet is
formed flat. At the press section, 100% of the sheet is pressed and
compacted to reach the necessary dryness and the sheet is further
dried on a Yankee and hood section. The sheet is then creped and
wound-up, thereby producing a flat sheet.
[0010] In an ATMOS.TM. system, a sheet is formed on a structured or
molding fabric and the sheet is further sandwiched between the
structured or molding fabric and a dewatering fabric. The sheet is
dewatered through the dewatering fabric and opposite the molding
fabric. The dewatering takes place with airflow and mechanical
pressure. The mechanical pressure is created by a permeable belt
and the direction of air flow is from the permeable belt to the
dewatering fabric. This can occur when the sandwich passes through
an extended pressure nip formed by a vacuum roll and the permeable
belt. The sheet is then transferred to a Yankee by a press nip.
Only about 25% of the sheet is slightly pressed by the Yankee while
approximately 75% of the sheet remains unpressed for quality. The
sheet is dried by a Yankee/Hood dryer arrangement and then dry
creped. In the ATMOS.TM. system, one and the same structured fabric
is used to carry the sheet from the headbox to the Yankee dryer.
Using the ATMOS.TM. system, the sheet reaches between about 35 to
38% dryness after the ATMOS.TM. roll, which is almost the same
dryness as a conventional press section. However, this
advantageously occurs with almost 40 times lower nip pressure and
without compacting and destroying sheet quality. Furthermore, a big
advantage of the ATMOS.TM. system is that it utilizes a permeable
belt which is highly tensioned, e.g., about 60 kN/m. This belt
enhances the contact points and intimacy for maximum vacuum
dewatering. Additionally, the belt nip is more than 20 times longer
than a conventional press and utilizes airflow through the nip,
which is not the case on a conventional press system.
[0011] Actual results from trials using an ATMOS.TM. system have
shown that the caliper and bulk of the sheet is 30% higher than the
conventional through-air drying (TAD) formed towel fabrics.
Absorbency capacity is also 30% higher than with conventional TAD
formed towel fabrics. The results are the same whether one uses
100% virgin pulp up to 100% recycled pulp. Sheets can be produced
with basis weight ratios of between 14 to 40 g/m.sup.2. The
ATMOS.TM. system also provides excellent sheet transfer to the
Yankee working at 33 to 37% dryness. A key aspect of the ATMOS.TM.
system is that it forms the sheet on the molding fabric and the
same molding fabric carries the sheet from the headbox to the
Yankee dryer. This produces a sheet with a uniform and defined pore
size for maximum absorbency capacity.
[0012] U.S. Pat. No. 7,585,395 to Quigley, the disclosure of which
is hereby expressly incorporated by reference in its entirety,
discloses a structured fabric for an ATMOS.TM. system. The fabric
utilizes an at least three float warp and weft structure, in a
symmetrical form.
[0013] U.S. Pat. No. 5,429,686 to Chiu et al., the disclosure of
which is hereby expressly incorporated by reference in its
entirety, discloses structured forming fabrics which utilize a
load-bearing layer and a sculptured layer. The fabrics utilize
impression knuckles to imprint the sheet and increase its surface
contour. This document, however, does not create pillows in the
sheet for effective dewatering of TAD applications, nor does it
teach using the disclosed fabrics on an ATMOS.TM. system and/or
forming the pillows in the sheet while the sheet is relatively wet
and utilizing a hi-tension press nip.
[0014] What is needed in the art is an efficient effective single
layer fabric weave pattern to be used in a papermaking machine.
SUMMARY OF THE INVENTION
[0015] In one aspect, the invention provides a papermaking machine
for the production of a fibrous web. The papermaking machine
including a plurality of rollers and a structured fabric moving
along the plurality of rollers. The structured fabric includes a
plurality of weft yarns and a plurality of warp yarns woven with
the plurality of weft yarns to produce a weave pattern. The
plurality of warp yarns being a plurality of paired warp yarn sets.
Each paired warp yarn set including a first warp yarn and a second
warp yarn, within the weave pattern the first warp yarn forms a
float over at least three weft yarns and weaves with a single weft
yarn immediately adjacent to the float. The second warp yarn having
a reverse pattern to the first warp yarn. The float of the first
warp yarn having a start that is at the same position as a finish
of the float of the second warp yarn.
[0016] In another aspect, the invention is a structured fabric for
use in a papermaking machine to produce a fibrous web. The
structured fabric includes a plurality of weft yarns and a
plurality of warp yarns woven with the plurality of weft yarns to
produce a weave pattern. The plurality of warp yarns being a
plurality of paired warp yarn sets. Each paired warp yarn set
including a first warp yarn and a second warp yarn, within the
weave pattern the first warp yarn forms a float over at least three
weft yarns and weaves with a single weft yarn immediately adjacent
to the float. The second warp yarn having a reverse pattern to the
first warp yarn. The float of the first warp yarn having a start
that is at the same position as a finish of the float of the second
warp yarn.
[0017] In yet another aspect the invention provides a fibrous web
having a fibrous construct with at least one formed surface
feature. The surface feature includes a topographical pattern
reflective of a weave pattern in a structured fabric used in a
papermaking machine, the structured fabric having a machine facing
side and a web facing side. The structured fabric includes a
plurality of weft yarns and a plurality of warp yarns woven with
the plurality of weft yarns to produce a weave pattern. The
plurality of warp yarns being a plurality of paired warp yarn sets.
Each paired warp yarn set including a first warp yarn and a second
warp yarn, within the weave pattern the first warp yarn forms a
float over at least three weft yarns and weaves with a single weft
yarn immediately adjacent to the float. The second warp yarn having
a reverse pattern to the first warp yarn. The float of the first
warp yarn having a start that is at the same position as a finish
of the float of the second warp yarn.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The above-mentioned and other features and advantages of
this invention, and the manner of attaining them, will become more
apparent and the invention will be better understood by reference
to the following description of embodiments of the invention taken
in conjunction with the accompanying drawings, wherein:
[0019] FIG. 1 shows a repeating weave pattern from the top side, or
web facing side, of an embodiment of a structured fabric of the
present invention, each `X` indicating a location where a warp yarn
passes over a weft yarn;
[0020] FIG. 2 illustrates the repeating weave pattern of the warp
yarns of the embodiment of FIG. 1;
[0021] FIG. 3 shows a surface motif of the weave pattern of FIGS. 1
and 2;
[0022] FIG. 4 illustrates a schematic cross-sectional view of an
embodiment of an ATMOS.TM. papermaking machine;
[0023] FIG. 5 illustrates a schematic cross-sectional view of
another embodiment of an ATMOS.TM. papermaking machine;
[0024] FIG. 6 illustrates a schematic cross-sectional view of
another embodiment of an ATMOS.TM. papermaking machine;
[0025] FIG. 7 illustrates a schematic cross-sectional view of
another embodiment of an ATMOS.TM. papermaking machine;
[0026] FIG. 8 illustrates a schematic cross-sectional view of
another embodiment of an ATMOS.TM. papermaking machine;
[0027] FIG. 9 illustrates a schematic cross-sectional view of
another embodiment of an ATMOS.TM. papermaking machine;
[0028] FIG. 10 illustrates a schematic cross-sectional view of
another embodiment of an ATMOS.TM. papermaking machine;
[0029] FIG. 11 illustrates a schematic cross-sectional view of
another embodiment of an ATMOS.TM. papermaking machine; and
[0030] FIG. 12 is a schematic process flow diagram of a
throughdrying process in accordance with this invention,
illustrating an uncreped throughdrying process with only one
throughdryer;
[0031] FIG. 13 is a schematic process flow diagram of a
throughdrying process in accordance with this invention,
illustrating an uncreped throughdrying process having two
throughdryers in series; and
[0032] FIG. 14 shows another schematic view of an apparatus for
practicing the present invention product and process.
[0033] Corresponding reference characters indicate corresponding
parts throughout the several views. The exemplification set out
herein illustrates one embodiment of the invention, in one form,
and such exemplification is not to be construed as limiting the
scope of the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
[0034] The particulars shown herein are by way of example and for
purposes of illustrative discussion of the embodiments of the
present invention only and are presented in the cause of providing
what is believed to be the most useful and readily understood
description of the principles and conceptual aspects of the present
invention. In this regard, no attempt is made to show structural
details of the present invention in more detail than is necessary
for the fundamental understanding of the present invention, and the
description is taken with the drawings making apparent to those
skilled in the art how the forms of the present invention may be
embodied in practice.
[0035] The present invention relates to a structured fabric for a
papermaking machine, a former for manufacturing a paper web, and
also to a former which utilizes the structured fabric, and in some
embodiments a belt press, in a papermaking machine, and the fibrous
web manufactured thereby.
[0036] The present invention also relates to a twin wire former
ATMOS.TM. system which utilizes the structured fabric which has
good resistance to pressure and excessive tensile strain forces,
and which can withstand wear/hydrolysis effects that are
experienced in an ATMOS.TM. system. The system may also include a
permeable belt for use in a high tension extended nip around a
rotating roll or a stationary shoe and a dewatering fabric for the
manufacture of premium tissue or towel grades. The fabric has key
parameters which include permeability, weight, caliper, and certain
compressibility.
[0037] Weave pattern 10 of structured fabric 28 of the present
invention is illustrated in FIGS. 1-3. FIG. 1 depicts a weave
pattern 10 from a top pattern view of the web facing side of the
fabric, also known as the papermaking surface. The numbers 1-10,
shown on the bottom of the pattern identify the warp, machine
direction (MD) yarns, while the right side numbers 1-10 show the
weft, cross direction (CD) yarns. The symbol `X` illustrates a
location where a warp yarn passes over a weft yarn and a box
without an `X` illustrates a location where a warp yarn passes
under a weft yarn. As shown in FIG. 1, the areas that are shaded
also having an `X` therein indicates long float warp yarns, which
float over three weft yarns. The shaded areas not having an X
illustrates weft yarns that are on top of warp yarns in structured
fabric 28. The non-shaded areas represent pocket areas 12 and 14,
with the `X` in the pocket area indicating a warp yarn that is at a
lower level than the immediately adjacent warp yarns, because this
warp yarn is woven with weft yarns on each side of the warp yarn
where the `X` is located in the unshaded pocket areas.
[0038] FIG. 2 illustrates the weave pattern of the warp yarns
relative to the weft yarns with the weft yarns being represented in
each line as the numbers and with the numbered line (1-10 arranged
vertically) being the pattern of the warp yarns. Each line
represents the warp yarn identified along the left side of the
Fig.
[0039] Referring now to FIG. 3 there is an illustration of what
weave pattern 10 produces within structured fabric 28. The pattern
of the web formed on fabric 28 will be a substantial reflection of
the pattern illustrated herein. Both FIGS. 1 and 3 have two example
pocket areas 12 and 14 boldly outlined schematically as a somewhat
square shape.
[0040] Topographical features of weave pattern 10 are repeated in
structured fabric 28 and are reflected upon web 38, as web 38 is
produced in the papermaking machine. The topographical features
cause a three-dimensional effect in web 38 reflective of weave
pattern 10, which enhances web 38 and imparts characteristics to
web 38, such as pocket depth and texture.
[0041] The warp yarns interact with the weft yarns to produce weave
patterns 10. Floats that occur over three weft yarns are in the
shaded portions of FIG. 1 with three sequential `X` s in the MD.
The three sequential shaded boxes not having an `X` in the CD are
where the weft yarn floats over the warp yarns, resulting in a
reciprocal float pattern, which can be thought of as the weft
floats in the CD being reciprocal to the warp floats in the MD.
Looking at the floats occurring in the MD each have a start and a
finish, which is where the warp yarn starts and finishes. For the
sake of convenience a start can be considered to occur at the lower
numbered weft yarn at which the float begins, as you go in a
positive sequential manner, and the finish being the higher number
weft yarn where the float ends. This means that a float that
continues to the next weave pattern will have a start occurring at
a higher numbered weft yarn than the finish. For example, in FIGS.
1-3, the floats that occurs with warp yarn 1 have a start between
weft yarns 8 and 9 and a finish between weft yarns 1 and 2. Warp
yarn 2 has it's start between weft yarns 5 and 6 and it's finish
between weft yarns 8 and 9. The adjacent floats of the warp yarns
have a start that is adjacent to a finish and a finish that is
adjacent to a start of another warp yarn. Looking at FIG. 2 it can
be seen that the start of the float of warp yarn 1 is where the
finish of the float of warp yarn 2 occurs, and so the yarn weave is
repeated in weave pattern 10 with the location of the start of a
warp float having a finish of a warp float in an immediately
adjacent warp yarn.
[0042] Further, each warp yarn sequentially passes beneath two
adjacent weft yarns either at the start or the finish of the warp
float. This can be seen to alternate in weave pattern 10 with the
odd numbered warp yarns having the two adjacent weft yarn weaves
prior to the start of the float and the even numbered warp yarns
having the two adjacent weft yarn weave following the finish of
each float. More specifically, looking at an odd numbered warp
yarn, such as warp yarn number 7, the warp yarn floats over three
weft yarns (1-3) goes under one weft yarn (4), over one weft yarn
(5), under two weft yarns (6 and 7), over one weft yarn (8), then
under two weft yarns (9 and 10). Looking at an even numbered warp
yarn, such as warp yarn 2, the warp yarn goes over one weft yarn
(1), under two weft yarns (2 and 3) over one weft yarn (4), under
one weft yarn (5), floats over three weft yarns (6-8), then goes
under two weft yarns (9 and 10).
[0043] The warp yarn weave sequence of the odd numbered warp yarns
can be thought of as being opposite or reciprocal to the even
numbered warp yarns, which can be seen, for example, by looking at
warp yarns 1 and 2 and starting between weft yarns 8 and 9, and
moving to the right in the weave of warp yarn 1 and to the left in
the weave of warp yarn 2. In so doing you first have the three yarn
float, followed by a single weave, then the warp yarns go under two
adjacent weft yarns, then a single weave, then the warp yarns go
under two more adjacent weft yarns back to the point of the
beginning of the floats.
[0044] Structured fabric 28 includes ten weft yarns and ten warp
yarns woven with the weft yarns to produce weave pattern 10. The
ten warp yarns may be grouped into five pairs of warp yarn sets.
Each paired warp yarn set includes a first warp yarn and an
adjacent second warp yarn. Within weave pattern 10 the first warp
yarn floats over at least three weft yarns and weaves with a
singular weft yarn then goes under two adjacent weft yarns, has a
single weave then goes under two more weft yarns. The second warp
yarn has a reciprocal pattern to the first warp yarn, which is a
way of saying, when viewed from an opposite direction of weaving
the yarn, it has an identical weave. The second warp yarn having a
float finish that occurs where the float start of the first warp
yarn occurs, when viewed in a sequential manner.
[0045] The first warp yarn of the next pair has the finish of it's
float at the same position as the start of the float in the second
warp yarn of the previous warp yarn pair. In this way as weave
pattern 10 is viewed in FIG. 2, it can be seen that the finish of
the float of each sequential warp yarn aligns with the start of the
float of the previous warp yarn.
[0046] Structured fabric 28 can also be treated and/or coated with
an additional polymeric material that is applied by, e.g.,
deposition. The material can be added cross-linked during
processing in order to enhance fabric stability, contamination
resistance, drainage, wearability, improve heat and/or hydrolysis
resistance and in order to reduce fabric surface tension. This aids
in sheet release and/or reduced drive loads. The treatment/coating
can be applied to impart/improve one or several of these properties
of the fabric. The topographical pattern in the paper web can be
changed and manipulated by use of adjustments to the specific
fabric weave by changes to the yarn diameter, yarn counts, yarn
types, yarn shapes, permeability, caliper and the addition of a
treatment or coating etc. In addition, a printed design, such as a
screen-printed design, of polymeric material can be applied to the
fabric to enhance its ability to impart an aesthetic pattern into
the web or to enhance the quality of the web. Finally, one or more
surfaces of the fabric or molding belt can be subjected to sanding
and/or abrading in order to enhance surface characteristics.
[0047] The characteristics of the individual yarns utilized in the
fabric of the present invention can vary depending upon the desired
properties of the final papermakers' fabric. For example, the
materials comprising yarns employed in the fabric of the present
invention may be those commonly used in papermakers' fabric. As
such, the yarns may be formed of polypropylene, polyester, nylon,
or the like. The skilled artisan should select a yarn material
according to the particular application of the final fabric.
[0048] The yarns may have differing dimensions and shapes relative
to adjacent yarns to thereby alter the size of the pocket areas.
One of the pocket areas 12 is illustrated in FIGS. 1 and 3 as a
darkened border and this one pocket area is representative of the
others that occur across weave pattern 10. Based on many factors
the size of the pocket area can be altered. For example if warp
yarns 10 and 3 are larger than warp yarns 1 and 2, then the
proportional width of the pocket area will be narrower, and
proportionally deeper. Pocket areas 12 and 14 are similar, but are
the mirror image of each other because of the pattern within. Note
that the `X`s occur in the opposite corners in pocket areas 12 and
14.
[0049] Some characteristics of the warp and weft yarns include
various cross-sections, such as circular, elliptical, polygonal,
rectangular and square. The meshes and yarn counts can be from 10
to 100 and more particularly between 26 and 86. The yarn
cross-sectional dimensions can vary from 0.10 mm to 1.0 mm, and
more particularly between 0.30 mm and 0.45 mm. The number of pocket
areas per square inch can be from 50 to 500 and more particularly
between 150 to 300. The permeability of fabric 28 may be from 100
to 1,000 cubic feet per minute (CFM) per ft.sup.2, and more
particularly between 350 and 700 CFM.
[0050] The paper that results from the forming process using the
inventive fabric has desirable attributes. Those attributes include
a basis weight in the range of 17-19.5 gm/m.sup.2, a caliper of
0.45 to 0.49 mm, a bulk of 22 to 27 cm.sup.3/gm, a machine
direction gram force per 50 mm of between 900 and 1300 gm, a
cross-machine direction gram force per 50 mm of between 500 and 700
gm, a machine direction stretch of 9-15%, and an absorbency of
15-18 gm of water/gm of paper.
[0051] By way of a non-limiting example, the structured fabric is a
single-layered woven fabric which can withstand high pressures,
heat, moisture concentrations, and which can achieve a high level
of water removal and also mold or emboss the paper web. These
characteristics provide a structured fabric appropriate for the
Voith ATMOS.TM. papermaking process. The fabric preferably has a
width stability and a suitable high permeability and preferably
utilizes hydrolysis and/or temperature resistant materials, as
discussed above. The fabric is preferably a woven fabric that can
be installed on an ATMOS.TM. machine as a pre-joined and/or seamed
continuous and/or endless belt. Alternatively, the structured
fabric can be joined in the ATMOS.TM. machine using, e.g., a
pin-seam arrangement or can otherwise be seamed on the machine.
[0052] The invention also provides for utilizing the structured
fabric disclosed herein on a machine for making a fibrous web,
e.g., tissue or hygiene paper web, etc., which can be, e.g., a twin
wire or a permeable belt ATMOS.TM. system. Referring again to the
drawings, and more particularly to FIGS. 4-10, there is a fibrous
web machine including a headbox 22 that discharges a fibrous slurry
between a forming fabric 26 and a structured fabric 28 having a
weave pattern 10. It should be understood that structured fabric 28
is an embodiment of the structured fabric discussed above in
connection with FIGS. 1-28. Rollers 30 and 32 direct fabric 26 in
such a manner that tension is applied thereto, against slurry 24
and structured fabric 28. Structured fabric 28 is supported by
forming roll 34 which rotates with a surface speed that matches the
speed of structured fabric 28 and forming fabric 26. Structured
fabric 28 has peaks and valleys as defined by weave pattern 10,
which give a corresponding structure to web 38 formed thereon.
Structured fabric 28 travels in a web direction, and as moisture is
driven from the fibrous slurry, structured fibrous web 38 takes
form. The moisture that leaves the slurry travels through forming
fabric 26.
[0053] The fibrous slurry is formed into a web 38 with a structure
that matches the shape of structured fabric 28. Forming fabric 26
is porous and allows moisture to escape during forming. Further,
water is removed through dewatering fabric 82. The removal of
moisture through fabric 82 does not cause compression of web 38
traveling on structured fabric 28.
[0054] Due to the formation of the web 38 with the structured
fabric 28 the pockets of the fabric 28 are fully filled with
fibers. Therefore, at the Yankee surface 52 the web 38 has a much
higher contact area, up to approximately 100%, as compared to the
prior art because the web 38 on the side contacting the Yankee
surface 52 is almost flat.
[0055] Referring to FIG. 4, there is shown an embodiment of the
process where a structured fibrous web 38 is formed. Structured
fabric 28 carries a three dimensional structured fibrous web 38 to
an advanced dewatering system 50, past vacuum box 67 and then to a
position where the web is transferred to Yankee dryer 52 and hood
section 54 for additional drying and creping before winding up on a
reel (not shown).
[0056] A shoe press 56 is placed adjacent to structured fabric 28,
holding fabric 28 in a position proximate Yankee dryer 52.
Structured fibrous web 38 comes into contact with Yankee dryer 52
and transfers to a surface thereof, for further drying and
subsequent creping.
[0057] A vacuum box 58 is placed adjacent to structured fabric 28
to achieve improved solids levels. Web 38, which is carried by
structured fabric 28, contacts dewatering fabric 82 and proceeds
toward vacuum roll 60. Vacuum roll 60 operates at a vacuum level of
-0.2 to -0.8 bar with a preferred operating level of at least -0.4
bar. Hot air hood 62 is optionally fit over vacuum roll 60 to
improve dewatering.
[0058] Optionally a steam box can be installed instead of the hood
62 supplying steam to the web 38. The steam box preferably has a
sectionalized design to influence the moisture re-dryness cross
profile of the web 38. The length of the vacuum zone inside the
vacuum roll 60 can be from 200 mm to 2,500 mm, with a preferable
length of 300 mm to 1,200 mm and an even more preferable length of
between 400 mm to 800 mm. The solids level of web 38 leaving
suction roll 60 is 25% to 55% depending on installed options. A
vacuum box 67 and hot air supply 65 can be used to increase web 38
solids after vacuum roll 60 and prior to Yankee dryer 52. Wire
turning roll 69 can also be a suction roll with a hot air supply
hood. As discussed above, roll 56 includes a shoe press with a shoe
width of 80 mm or higher, preferably 120 mm or higher, with a
maximum peak pressure of less than 2.5 MPa. To create an even
longer nip to facilitate the transfer of web 38 to Yankee dryer 52,
web 38 carried on structured fabric 28 can be brought into contact
with the surface of Yankee dryer 52 prior to the press nip
associated with shoe press 56. Further, the contact can be
maintained after structured fabric 28 travels beyond press 56.
[0059] Now, additionally referring to FIG. 5, there is shown yet
another embodiment of the present invention, which is substantially
similar to the invention illustrated in FIG. 4, except that instead
of hot air hood 62, there is a belt press 64. Belt press 64
includes a permeable belt 66 capable of applying pressure to the
machine side of structured fabric 28 that carries web 38 around
vacuum roll 60. Fabric 66 of belt press 64 is also known as an
extended nip press belt or a link fabric, which can run at 60 KN/m
fabric tension with a pressing length that is longer than the
suction zone of roll 60.
[0060] Preferred embodiments of the fabric 66 and the required
operation conditions are also described in PCT/EP2004/053688 and
PCT/EP2005/050198 which are herewith incorporated by reference.
[0061] The above mentioned references are also fully applicable for
dewatering fabrics 82 and press fabrics 66 described in the further
embodiments.
[0062] Belt 66 is a specially designed extended nip press belt 66,
made of, for example reinforced polyurethane and/or a spiral link
fabric. Belt 66 also can have a woven construction. Such a woven
construction is disclosed, e.g., in EP 1837439. Belt 66 is
permeable thereby allowing air to flow there through to enhance the
moisture removing capability of belt press 64. Moisture is drawn
from web 38 through dewatering fabric 82 and into vacuum roll
60.
[0063] Referring to FIG. 6, there is shown another embodiment of
the present invention which is substantially similar to the
embodiment shown in FIG. 5 with the addition of hot air hood 68
placed inside of belt press 64 to enhance the dewatering capability
of belt press 64 in conjunction with vacuum roll 60.
[0064] Referring to FIG. 7, there is shown yet another embodiment
of the present invention, which is substantially similar to the
embodiment shown in FIG. 5, but including a boost dryer 70 which
encounters structured fabric 28. Web 38 is subjected to a hot
surface of boost dryer 70, and structured web 38 rides around boost
dryer 70 with another woven fabric 72 riding on top of structured
fabric 28. On top of woven fabric 72 is a thermally conductive
fabric 74, which is in contact with both woven fabric 72 and a
cooling jacket 76 that applies cooling and pressure to all fabrics
and web 38. The pressing process does not negatively impact web
quality. The drying rate of boost dryer 70 is above 400 kg/hr
m.sup.2 and preferably above 500 kg/hr m.sup.2. The concept of
boost dryer 70 is to provide sufficient pressure to hold web 38
against the hot surface of the dryer thus preventing blistering.
Steam that is formed at the knuckle points of fabric 28 passes
through fabric 28 and is condensed on fabric 72. Fabric 72 is
cooled by fabric 74 that is in contact with cooling jacket 76,
which reduces its temperature to well below that of the steam. Thus
the steam is condensed to avoid a pressure build up to thereby
avoid blistering of web 38. The condensed water is captured in
woven fabric 72, which is dewatered by dewatering device 75. It has
been shown that depending on the size of boost dryer 70, the need
for vacuum roll 60 can be eliminated. Further, depending on the
size of boost dryer 70, web 38 may be creped on the surface of
boost dryer 70, thereby eliminating the need for Yankee dryer
52.
[0065] Referring to FIG. 8, there is shown yet another embodiment
of the present invention substantially similar to the invention
disclosed in FIG. 5 but with an addition of an air press 78, which
is a four roll cluster press that is used with high temperature air
and is referred to as a High Pressure Through Air Dryer (HPTAD) for
additional web drying prior to the transfer of web 38 to Yankee
dryer 52. Four-roll cluster press 78 includes a main roll, a vented
roll, and two cap rolls. The purpose of this cluster press is to
provide a sealed chamber that is capable of being pressurized. The
pressure chamber contains high temperature air, for example,
150.degree. C. or higher and is at a significantly higher pressure
than conventional TAD technology, for example, greater than 1.5 psi
resulting in a much higher drying rate than a conventional TAD. The
high-pressure hot air passes through an optional air dispersion
fabric, through web 38 and fabric structured 28 into a vent roll.
The air dispersion fabric may prevent web 38 from following one of
the cap rolls. The air dispersion fabric is very open, having a
permeability that equals or exceeds that of fabric structured 28.
The drying rate of the HPTAD depends on the solids content of web
38 as it enters the HPTAD. The preferred drying rate is at least
500 kg/hr m.sup.2, which is a rate of at least twice that of
conventional TAD machines.
[0066] Advantages of the HPTAD process are in the areas of improved
sheet dewatering without a significant loss in sheet quality and
compactness in size and energy efficiency. Additionally, it enables
higher pre-Yankee solids, which increase the speed potential of the
invention. Further, the compact size of the HPTAD allows for easy
retrofitting to an existing machine. The compact size of the HPTAD
and the fact that it is a closed system means that it can be easily
insulated and optimized as a unit to increase energy
efficiency.
[0067] Referring to FIG. 9, there is shown another embodiment of
the present invention. This is significantly similar to the
embodiments shown in FIGS. 5 and 8 except for the addition of a
two-pass HPTAD 80. In this case, two vented rolls are used to
double the dwell time of structured web 38 relative to the design
shown in FIG. 8. An optional coarse mesh fabric may be used as in
the previous embodiment. Hot pressurized air passes through web 38
carried on structured fabric 28 and onto the two vent rolls. It has
been shown that depending on the configuration and size of the
HPTAD, more than one HPTAD can be placed in series, which can
eliminate the need for roll 60.
[0068] Referring to FIG. 10, a conventional twin wire former 90 may
be used to replace the crescent former shown in previous examples.
The forming roll can be either a solid or open roll. If an open
roll is used, care must be taken to prevent significant dewatering
through the structured fabric to avoid losing basis weight in the
pillow areas. The outer forming fabric 93 can be either a standard
forming fabric or one such as that disclosed in U.S. Pat. No.
6,237,644. The inner fabric 91 should be a structured fabric that
is much coarser than the outer forming fabric 90. For example,
inner fabric 91 may be similar to structured fabric 28. A vacuum
roll 92 may be needed to ensure that the web stays with structured
fabric 91 and does not go with outer wire 90. Web 38 is transferred
to structured fabric 28 using a vacuum device. The transfer can be
a stationary vacuum shoe or a vacuum assisted rotating pick-up roll
94. The second structured fabric 28 is at least the same coarseness
and preferably coarser than first structured fabric 91. The process
from this point is the same as the process previously discussed in
conjunction with FIG. 5. The registration of the web from the first
structured fabric to the second structured fabric is not perfect,
and as such some pillows will lose some basis weight during the
expansion process, thereby losing some of the benefit of the
present invention. However, this process option allows for running
a differential speed transfer, which has been shown to improve some
sheet properties. Any of the arrangements for removing water
discussed above as may be used with the twin wire former
arrangement and a conventional TAD.
[0069] Referring to FIG. 11 there is illustrated another ATMOS.TM.
system having many elements as discussed above. The ATMOS.TM.
system of FIG. 11, is further described in WO 2010/069695 having a
priority date of Dec. 19, 2008. Belt press 64 constitutes a first
pressing zone where web 38 is pressed. Web 38 proceeds to a second
pressing zone 65 where web 38 is pressed again.
[0070] Now, additionally referring to FIGS. 12-14 there are
illustrated types of TAD systems, specifically those described in
the patent record of Kimberly-Clark (See WO 2005/073461 A1) and
Procter & Gamble (See WO 2009/069046 A1). These systems are
discussed using various fabrics, of which structured fabric 28,
discussed above, may be used in place of the fabrics discussed
hereinbelow. FIG. 12 illustrates one of many papermaking processes
to which the invention is applicable. Shown is an uncreped
through-dried tissue process in which a twin wire former having a
layered papermaking headbox 205 injects or deposits a stream of an
aqueous suspension of papermaking fibers between two forming
fabrics 206 and 207. Forming fabric 207 being the same as
structured fabric 28, discussed above. Forming fabric 207 serves to
support and carry the newly-formed wet web 208 downstream in the
process as the web is partially dewatered to an appropriate
consistency, such as about 10% dry weight percent. As shown in this
example, profiling of the web in accordance with this invention
takes place at the point in the process where the exhaust gas
recovery plenum 211 and the vacuum box(es) 210 are positioned.
Additional dewatering of the wet web can be carried out, such as by
vacuum suction, using one or more steam boxes in conjunction with
one or more vacuum suction boxes (not shown) while the wet web is
supported by the forming fabric 207.
[0071] The wet web 208 is then transferred from the forming fabric
207 to a transfer fabric 213 traveling at a slower speed than the
forming fabric 207 in order to impart increased MD stretch into the
web. The transfer is carried out to avoid compression of the wet
web, preferably with the assistance of a vacuum shoe 214. Although
not shown, it is within the scope of this invention for the
profiling to take place at any point while the web is supported by
the transfer fabric as well as the forming fabric 207.
[0072] The web is then transferred from the transfer fabric 213 to
the throughdrying fabric 220 with the aid of a vacuum transfer roll
215 or a vacuum transfer shoe. Transfer is preferably carried out
with vacuum assistance to ensure deformation of the sheet to
conform to the throughdrying fabric, thus yielding desired bulk,
flexibility, CD stretch and appearance.
[0073] The vacuum shoe (negative pressure) can be supplemented or
replaced by the use of positive pressure from the opposite side of
the web to blow the web onto the next fabric in addition to or as a
replacement for sucking it onto the next fabric with vacuum. Also,
a vacuum roll or rolls can be used to replace the vacuum
shoe(s).
[0074] While supported by the throughdrying fabric 220, the web is
dried to a final consistency, typically about 94 percent or
greater, by the throughdryer 225 and thereafter transferred to a
carrier fabric 230. The dried basesheet 227 is transported to the
reel 235 using carrier fabric 230 and an optional carrier fabric
231. An optional pressurized turning roll 233 can be used to
facilitate transfer of the web from carrier fabric 230 to fabric
231. Although not shown, reel calendering or subsequent off-line
calendering can be used to improve the smoothness and softness of
the basesheet.
[0075] The hot air used to dry the web while passing over the
throughdryer is provided by a burner 240 and distributed over the
surface of the throughdrying drum using a hood 241. The air is
drawn through the web into the interior of the throughdrying drum
via fan 243 which serves to circulate the air back to the burner.
In order to avoid moisture build-up in the system, a portion of the
spent air is vented 245, while a proportionate amount of fresh
make-up air 247 is fed to the burner. The exhaust gas recycle
stream 250 provides exhaust gas to the exhaust gas recovery plenum
211 operatively positioned in the vicinity of one or more vacuum
suction boxes 210, such that exhaust gas fed to the exhaust gas
recovery plenum is drawn through the web, through the papermaking
fabric and into the vacuum box(es) in order to control the
consistency profile the web. The humidity of the recycled exhaust
gas can be about 0.15 pounds of water vapor or greater per pound of
air, more specifically about 0.20 pounds of water vapor or greater
per pound of air, and still more specifically about 0.25 pounds of
water vapor or greater per pound of air.
[0076] FIG. 13 is a schematic process flow diagram of another
throughdrying process in accordance with this invention, similar to
that illustrated in FIG. 12, but in which two throughdryers are
used in series to dry the web. The components of the second
throughdryer are given the same reference numbers used for the
first throughdryer, but distinguished with a "prime". When two
throughdryers are used as shown, the exhaust gas from the first
(primary) throughdryer is recycled to the exhaust gas recovery
plenum 211 because of its relatively greater heat value. As
previously noted, if the throughdryers are operated in such a
fashion that the relative heat value of the second throughdryer is
greater than the first for the given application, the exhaust gas
from the second throughdryer can be used for the recycle stream to
the exhaust gas recovery plenum 211.
[0077] Optionally, exhaust gas from the second throughdryer can be
used to heat and/or profile the dewatered web by providing an
exhaust gas recycle stream 255 which, as shown, is directed to
exhaust gas recovery plenum 256 opposite vacuum roll or shoe 257.
Any of the web-contacting or sheet-contacting rolls in the vicinity
of vacuum roll or shoe 257 are also suitable locations for
introducing the exhaust gas for purposes of profiling in accordance
with this invention should these rolls be equipped with vacuum. As
an alternative (not shown), a vacuum box can be placed within the
loop of fabric 213 and the plenum 256 can be placed operatively
opposite this vacuum box to profile the web.
[0078] As described supra, one fibrous structure useful in
achieving the fibrous structure paper product of the present
invention is the through-air-dried (TAD), differential density
structure described in U.S. Pat. No. 4,528,239. Such a structure
may be formed according to the nonlimiting embodiment of the
apparatus exemplified in FIG. 14. The apparatus 300 includes a head
box 310, a Fourdrinier section 320 comprising a Fourdrinier wire
322, a press section 330 comprising a TAD carrier fabric 332, which
is the same as structured fabric 28 discussed above and a Yankee
Dryer 340.
[0079] In one embodiment, it is possible to operate the papermaking
machine such that there is a differential velocity between the TAD
carrier fabric 332 and the Fourdrinier wire 322 to provide
increased fibers in the pillow regions of the fibrous web. The
Fourdrinier wire 322 may even run at a higher speed than the TAD
carrier fabric 332.
[0080] As described supra, it is found that some consumers prefer a
relatively bulky product as compared to a relatively cushiony
product. It is surprisingly found that in addition to the
process/additive changes described supra, in some embodiments
during the transfer of the slurry from the Fourdrinier wire to the
TAD carrier fabric, if the speed of the Fourdrinier wire and the
speed of the TAD carrier fabric are approximately equal, or if the
Fourdrinier wire is operating at a relatively slower speed than the
TAD carrier fabric, then a relatively high amount of fibers are
distributed in the walls of the formed features compared to the
formed features of the prior art and a relatively bulky product may
be achieved. In other embodiments, the speed of the Fourdrinier
wire is from about 0% to about -6% of the TAD carrier fabric
(wire-to-press draw of from about 0% to about -6%). One of skill in
the art will appreciate that a resin coated belt may be used
instead of a TAD carrier fabric.
[0081] While this invention has been described with respect to at
least one embodiment, the present invention can be further modified
within the spirit and scope of this disclosure. This application is
therefore intended to cover any variations, uses, or adaptations of
the invention using its general principles. Further, this
application is intended to cover such departures from the present
disclosure as come within known or customary practice in the art to
which this invention pertains and which fall within the limits of
the appended claims.
* * * * *