U.S. patent application number 12/566979 was filed with the patent office on 2010-10-07 for paper machine clothing with edge reinforcement.
Invention is credited to Marc Begin, Robert Eberhardt, Lippi A. Fernandes, Jacqueline Marz, Sanjay Patel, Matthew Ryan, Matthias Schmitt.
Application Number | 20100252217 12/566979 |
Document ID | / |
Family ID | 42825217 |
Filed Date | 2010-10-07 |
United States Patent
Application |
20100252217 |
Kind Code |
A1 |
Eberhardt; Robert ; et
al. |
October 7, 2010 |
PAPER MACHINE CLOTHING WITH EDGE REINFORCEMENT
Abstract
The invention relates to a clothing for a web-processing
machine, in particular a tissue machine, including a flat basic
structure with an upper side and a lower side, and with a coating
which is applied to the upper side and/or lower side and includes
at least one polymer material. At least one polymer material is a
polyurea, in particular an elastomer polyurea.
Inventors: |
Eberhardt; Robert;
(Ellwangen, DE) ; Marz; Jacqueline; (Heidenheim,
DE) ; Schmitt; Matthias; (Munchen, DE) ;
Fernandes; Lippi A.; (Brummen, NL) ; Patel;
Sanjay; (Halmstad, SE) ; Begin; Marc;
(Raleigh, NC) ; Ryan; Matthew; (Appleton,
WI) |
Correspondence
Address: |
TAYLOR IP, P.C.
P.O. Box 560, 142. S Main Street
Avilla
IN
46710
US
|
Family ID: |
42825217 |
Appl. No.: |
12/566979 |
Filed: |
September 25, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/US08/58135 |
Mar 25, 2008 |
|
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|
12566979 |
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Current U.S.
Class: |
162/289 |
Current CPC
Class: |
D21F 1/0027
20130101 |
Class at
Publication: |
162/289 |
International
Class: |
D21G 9/00 20060101
D21G009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2007 |
DE |
10 2007 015 055.7 |
Claims
1. A clothing for a machine which processes a web of fibrous
material, the clothing comprising: a flat basic structure including
an upper side, a lower side, and a coating applied to at least one
of said upper side and said lower side, said coating including at
least one polymer material wherein said polymeric material is a
polyurea.
2. The clothing according to claim 1, wherein said polyurea is an
elastomer polyurea.
3. The clothing according to claim 1, wherein said coating is
applied in a plurality of areas of said basic structure only on at
least one of said upper side and said lower side of said basic
structure.
4. The clothing according to claim 1, wherein said coating is
applied to at least one of all of said upper side and all of said
lower side of said basic structure
5. The clothing according to claim 1, wherein said flat basic
structure is a fabric.
6. The clothing according to claim 5, wherein said fabric includes
a plurality of threads in an area of said fabric in which said
coating is applied, said plurality of threads in said area being
covered at least partly by said coating.
7. The clothing according to claim 5, wherein said fabric is a
three-dimensionally structured fabric.
8. The clothing according to claim 7, wherein said
three-dimensionally structured fabric is a through-air dryer
mesh.
9. The clothing according to claim 5, wherein said fabric includes
at least one of a plurality of polyethylene terephthalate threads,
a plurality of polyamide threads, and a plurality of polyphenylene
sulfide threads.
10. The clothing according to claim 1, wherein said polyurea is
present in said coating with a weight fraction of at least 10%.
11. The clothing according to claim 1, wherein said polyurea is a
two-component polyurea.
12. The clothing according to claim 1, wherein said basic structure
includes a plurality of points covered with said coating, said
basic structure having been subjected, prior to said coating being
applied, to a surface treatment at said plurality of points which
are covered with said coating.
13. The clothing according to claim 1, wherein said coating
includes an additive configured for at least one of increasing a
wear stability of said coating and reducing a coefficient of
friction of said coating.
14. The clothing according to claim 13, wherein said additive
includes at least one of colloidal silicone dioxide, ultra high
molecular weight polyethylene, and boronitride.
15. The clothing according to claim 13, wherein said additive
includes a plurality of particles.
16. The clothing according to claim 13, wherein said additive
includes a plurality of nanoparticles.
17. The clothing according to claim 1, wherein said basic structure
includes two longitudinal edge regions each including a
longitudinal edge of said basic structure, said coating being
applied in each of said longitudinal edge regions.
18. The clothing according to claim 17, wherein said coating
extends from each said longitudinal edge over approximately 3/8
inch to approximately 1 inch in a cross machine direction.
19. The clothing according to claim 1, wherein said basic structure
includes two transverse edge regions each including a transverse
edge of said basic structure, each transverse edge extending in a
cross machine direction of the clothing, said transverse edges
being joined together and thereby rendering said basic structure
endless and forming a seam region, said coating being applied in
said transverse edge regions.
Description
[0001] This is a continuation of PCT application No.
PCT/U.S.08/58135, entitled "PAPER MACHINE CLOTHING WITH EDGE
REINFORCEMENT", filed Mar. 25, 2008, which is incorporated herein
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a clothing for a web-processing
machine, in particular a paper machine, paperboard machine or
tissue machine.
[0004] 2. Description of the Related Art
[0005] To improve wear resistance and/or hydrolysis resistance,
clothings for web-processing machines are often equipped in their
edge region and/or seam region with a coating. These coatings
frequently have the disadvantage of not adhering firmly enough to
the threads of the, for example woven, structure of the clothing,
and therefore, of flaking off the threads when exposed to the
effects of tensile stress, abrasion forces, heat and moisture. In
particular on dryer fabrics or through-air dryer ("TAD") meshes,
which are exposed to high temperature combined with a high level of
moisture, and for this reason, are often equipped with or made from
PET threads, it is a problem that the coatings known from the prior
art flake off the PET threads after a short time already. These
coatings frequently also improve the hydrolysis resistance of such
meshes only to a limited extent or not at all.
[0006] What is needed in the art is a clothing of the type
initially referred to on which the described flaking does not occur
or occurs only to a much reduced extent and through which the
hydrolysis resistance of the herewith equipped clothing is
improved.
SUMMARY OF THE INVENTION
[0007] The present invention provides a clothing for a
web-processing machine, in particular a paper machine, paperboard
machine or tissue machine, including a flat basic structure with an
upper side and a lower side, and with a coating which is applied to
the upper side and/or lower side and includes at least one polymer
material, whereby the at least one polymer material is a polyurea,
for example, an elastomer polyurea.
[0008] By providing a coating containing a polyurea, a coating with
a much improved adherence to the basic structure of the clothing, a
far higher resistance to abrasion and a far higher resistance to
chemicals is provided. The penetration of moisture into the
material of the basic structure is prevented by the coating,
leading to a clear improvement in the hydrolysis resistance of the
clothing that is provided with said coating.
[0009] The inventive clothing is used in this case preferably but
not exclusively, for applications in which the clothing is exposed
to a high level of moisture combined with a high temperature. For
example the inventive clothing is used as a dryer fabric or a TAD
mesh. It is, however, also possible that the inventive clothing is
a press felt or a forming screen.
[0010] One embodiment of the invention provides that the coating is
applied only in some areas on the upper and/or underside of the
basic structure. Alternatively it may be provided that the coating
is applied to the entire upper- and/or underside of the basic
structure. "In some areas" is to be understood specifically to mean
that the coating is applied only to a section of the width of the
clothing.
[0011] Preferably the flat basic structure is a fabric. The fabric
is hereby formed, for example, by monofilament threads. In the
section where the coating is applied the threads which form the
fabric are advantageously covered at least partly, for example,
completely, by the coating. The entire fabric may be covered by the
coating in that area in which the coating is applied to the fabric.
In this way the threads of the fabric are protected from harmful
ambient influences.
[0012] In addition, in the area(s) which is (are) provided with the
coating the threads of the fabric are, for example, connected with
each other due to the coating at the thread crossing points and/or
thread contact areas. Thread contact areas are created, for
example, when the polyurea coating is applied to that area in which
the threads run parallel to each other and touch each other. This
improves the dimensional stability of the inventive clothing. In
addition, the accumulation of dirt in the thread crossing points is
hereby clearly reduced. Since the threads are connected with each
other, the interior abrasion of the clothing is further obviated or
at least minimized, determined by the relative movement of the
threads between each other
[0013] In addition, trials conducted by the applicant have shown
that the polyurea coating can accumulate also between the threads
at the thread crossing points or contact areas and are separated
from each other by this coating and are, so to speak, elastically
stratified on the coating. In other words, the polyurea coating
forms an elastic intermediate layer between threads at thread
contact or thread crossing points.
[0014] In order to produce the inventive clothing it is possible to
first produce the basic structure and to subsequently provide the
completed basic structure with the coating. If the basic structure,
for example, is in the embodiment of a woven fabric, then the
fabric in this scenario is produced--in other words woven--first
and is then provided with the coating.
[0015] Alternatively, it is possible to first provide a portion of
the threads which make up the fabric with the coating, and to
subsequently interweave the so coated threads during the production
of the fabric.
[0016] Advantageously the basic structure is permeable for water
and air. Depending on the requirements, the coating can be applied
in this connection such that the permeability is not affected by
the coating, meaning that the clothing in the coated area has the
same or essentially the same permeability as in the uncoated area.
Alternatively, the permeability of the clothing in the coated area
can be lower than the permeability in the uncoated area. For
example, the permeability of the clothing in the coated area can be
a maximum of 20% less, for example a maximum of 15% less, for
example a maximum of 10% less than in the uncoated area. With a
fabric this is achieved, for example, by filling out the meshes of
the fabric in at least some areas.
[0017] In addition, it is possible that the clothing in the coated
area is impermeable for air and water and that the clothing in the
uncoated area is permeable. This is achieved in particular by the
upper side and the lower side of the basic structure in the coated
area being covered completely by the coating.
[0018] The coating is applied to the basic structure such that the
thickness of the clothing in the coated area is equal to or only
non-essentially greater than that in the uncoated area. In this
connection, essentially greater is understood to be a clothing
thickness in the coated area which is a maximum 15%, in particular
a maximum 10% greater than in the uncoated area. The thickness of
the coating can be in the range of approximately 1 .mu.m to
approximately 6 .mu.m, for example, in the range of approximately 3
.mu.m to approximately 30 .mu.m. Layer thicknesses in the range of
1-60 .mu.m are advantageous if the clothing is permeable in the
area of the coating.
[0019] The fabric is, for example, a three-dimensionally structured
fabric, in particular a TAD mesh.
[0020] The inventive clothing can be used on a tissue machine on
which the tissue web is formed on the clothing from the fibrous
suspension and the formed tissue web is then conveyed on this
clothing as far as the Yankee drying cylinder. The tissue web is
charged in this case upstream from the drying cylinder with a hot
air current and/or steam current.
[0021] For the previously mentioned application it makes sense in
particular for the fabric to include polyethylene terephthalate
("PET") and/or polyamide ("PA") and/or polyphenylene sulfide
("PPS") threads. It is therefore possible that the fabric
representing the basic structure is formed entirely from threads of
one of the PET, PA or PPS materials. It is, however, also possible
that the fabric is formed partially from threads from one of the
first of the aforementioned materials and partially from threads of
one of the subsequently aforementioned materials.
[0022] It has been discovered that the inventive coating already
possesses the advantageous properties when the polyurea is present
in the coating with a weight fraction of 10% or more.
[0023] The polyurea can be a two-component polyurea, whereby the
one component of the two is, for example, a diisocyanate and the
other of the two components is, for example, a diamine. The use of
a diamine is advantageous in particular due to its low viscosity,
which permits auxiliary materials to be added without the viscosity
and the mix behavior being affected thereby. Used in particular is
a diisocyanate known under the trade-name Araltide AY 8683. Also
preferably used is a diamine known under the trade-name Hardener HY
8683
[0024] It is also conceivable that the polyurea is a
single-component polyurea. A single-component polyurea of this type
may, for example, be moisture-hardening or moisture-crosslinking. A
catalyst can be used to speed up the hardening or cross-linking
reaction. Products to be considered as single-component polyurea
are, for example, products produced by "Nitroil Performance
Chemicals" under the label "PC MD 8.6" or "PC MD 11".
[0025] Single or two-component polyurea may, for example, be
applied onto the basic structure in diluted form or as a solution
in an organic solvent. The solvent used in this application is in
particular a non-protic solvent. For example, THF
(Tetrahydrofurane) would be suitable as a non-protic solvent.
[0026] The coating including the polyurea possesses a temperature
stability of 180.degree. C. to 220.degree. C. at a temperature
reaction time of at least 2 minutes. In this context, temperature
stability is to be understood to mean that the coating shows no
degradation aspect, visible to the naked eye.
[0027] To improve further the adherence of the coating to the basic
structure, an embodiment of the invention provides for the basic
structure to be subjected, prior to the coating being applied, to a
surface treatment at least at those points which are covered with
the coating. The surface treatment can include, either alone or in
combination, cleaning with a solvent or by way of corona discharge.
The surface treatment can, for example, additionally include
treatment of the basic structure with atmospheric pressure plasma.
In this context, it is also possible that the atmospheric pressure
plasma is an oxygen plasma.
[0028] A second embodiment of the present invention provides for
the coating to contain an additive which increases the wear
stability of the coating and/or reduces the coefficient of friction
of the coating. In particular, colloidal silicone dioxide, ultra
high molecular weight polyethylene ("UHMW PE") or boronitride can
be cited, by way of example, as additives for use alone or in
combination in this connection.
[0029] In this connection, the additive may include particles, in
particular nanoparticles, or for it to be formed by particles, in
particular nanoparticles.
[0030] As it is in particular the longitudinal edges of the basic
structure which are exposed to greater abrasion and/or an increased
temperature stress, then it is an advantage in particular for the
coating to be applied in the region of the two longitudinal edges
of the basic structure. The increased temperature stress is caused
especially in that the longitudinal edges along the edge areas of
the clothing are not covered by a paper web and are therefore, for
example, in a TAD machine, subjected directly to the full hot air
flow.
[0031] Especially in order to increase the hydrolysis stability it
is useful if the coating--when viewed in transverse machine
direction--extends from each of the two longitudinal edges in
direction toward the center of the clothing to a point where at
least the two areas of the clothing are coated which are never in
contact with the paper web during operation of the clothing. In
order to further increase the hydrolysis stability of the inventive
clothing the coating can extend from each of the two longitudinal
edges in direction toward the center of the clothing to a point
that the two areas of the clothing are coated which only come into
contact with the paper web only temporarily while the paper web is
in contact with the clothing, for example, edge strip areas.
[0032] In order to increase the abrasion resistance, coating can
extend from the longitudinal edges over approximately 3/8 inch to 1
inch in the cross machine direction ("CMD direction"). In order to
increase the hydrolysis stability the coating can extend from the
longitudinal edges approximately 5 cm to 20 cm in CMD
direction.
[0033] Also exposed to greater wear is the seam region. A third
embodiment of the present invention thus provides for the basic
structure to have transverse edges, which extend in the CMD
direction and can be joined together in order to render the basic
structure endless while constructing a seam region, and for the
coating to be applied in the region of the transverse edges.
[0034] Possible application methods for applying the coating are,
for example, dip-coating and subsequent wiping in order to equalize
the coating, roll coating, knife-coating, spray coating or
extrusion coating.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] 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:
[0036] FIG. 1 shows a first embodiment of an inventive clothing in
a plan view of its upper side;
[0037] FIG. 2 shows the clothing from FIG. 1 in cross-sectional
direction;
[0038] FIG. 3 shows a top view of the upper side of a second
embodiment of an inventive clothing;
[0039] FIG. 4 shows a cross-directional view of the clothing
depicted in FIG. 3; and
[0040] FIG. 5 is a device for the production of an inventive
clothing.
[0041] Corresponding reference characters indicate corresponding
parts throughout the several views. The exemplifications set out
herein illustrate embodiments of the invention, and such
exemplifications are not to be construed as limiting the scope of
the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
[0042] Referring now to the drawings, and more particularly to FIG.
1, there is shown an embodiment of inventive clothing 1 in a plan
view of upper side 2.
[0043] The represented clothing 1 is a TAD mesh. Mesh 1 has a flat
basic structure which is formed by permeable fabric 3 woven from
PET threads 4 and 5.
[0044] In addition mesh 1 includes coating 6 which is applied
respectively in the region of two longitudinal edges 7 and 8
extending in the machine direction ("MD direction") and in edge
areas 10, 11 on fabric 3 on upper side 2 and on lower side 9 (shown
only in FIG. 2). Between two coated edge areas 10, 11 is an
uncoated area 13.
[0045] According to the present invention, coating 6 includes a
polymer material, which in the example in question is formed by a
two-component elastomer polyurea and nanoparticles 12 of
boronitride. The wear stability of coating 6 is increased by
boronitride nanoparticles 12.
[0046] Coated edge areas 10, 11 extend in this case respectively by
approximately 1 inch from longitudinal edges 7 and 8 in the CMD
direction. The coating is applied in this case such that upper side
2 and lower side 9 of fabric 3 in coated edge areas 10, 11 are
covered completely by the coating and edge areas 10, 11 are
impermeable.
[0047] FIG. 2 shows mesh 1 from FIG. 1 in the cross-sectional
direction (CMD direction) in the region of coated edge area 10 and
adjacent uncoated area 13 of fabric 3. It is evident that the
thickness of mesh 1 in coated edge area 10 is only non-essentially
greater than in uncoated area 13, whereby in the case in question
the clothing thickness in coated edge area 10 is a maximum 5%
greater than in uncoated area 13.
[0048] FIG. 3 shows a top view of upper side 102 of one embodiment
of additional inventive clothing 101.
[0049] Illustrated clothing 1 represents a dryer fabric or TAD
mesh. Mesh 101 has a flat basic structure which is formed by woven
and permeable fabric 103 which consists of PET threads 104 and
105.
[0050] Mesh 101 further includes coating 106 which is applied
respectively onto top side 102 of fabric 103 in edge regions 110,
111 which run along two longitudinal edges 107 and 108 progressing
in MD direction, and onto underside 109 which is only depicted in
FIG. 4. Non-coated area 113 is located between two coated edge
areas 110, 111.
[0051] In accordance with the present invention coating 106
includes a polymer material which, in the current example, is
composed by a single-component, or two-component elastomer
polyurea.
[0052] The two broken lines in the illustration in FIG. 3 separate
paper contact area 114 of clothing 101. That is, they separate an
area which may be brought into contact with a paper web during
operation of inventive mesh 101 from two paper-free areas 115 and
116 with which the paper web is never in contact during
operation.
[0053] As can be seen in the illustration in FIG. 3 coating
106--when viewed in cross machine direction (CMD)--extends from
each of two longitudinal edges 107 and 108 in the direction toward
the center of clothing 101 to a point where at least two areas 115
and 116 of clothing 101 are coated which are never in contact with
the paper web during operation of clothing 101. In this example,
coating 106 even extends from each of two longitudinal edges 107
and 108 in CMD direction into a section of the paper contact area
114.
[0054] In this scenario, coating 106 is applied onto upper side 102
and underside 109 of fabric 103 in such a way that threads 104 and
105 are completely enveloped in coating 106. In addition, threads
104, 105 are connected with each other through coating 106 at
thread crossing points 117. Coating 106 has a thickness which may
be in the range of approximately 1 .mu.m to approximately 60 .mu.m.
The permeability of clothing 101 is not substantially affected by
coating 106, so that fabric 103 has a permeability in non-coated
region 113 which is essentially the same as the permeability in two
coated edge sections 110, 111.
[0055] "Essentially the same permeability" in this context is to be
understood to mean that the permeability in coated edge sections
110, 111 is a maximum of 15%, for example, a maximum of 10% less
than the permeability in non-coated section 113.
[0056] FIG. 4 shows mesh 101 of FIG. 3 in cross direction
(CMD-direction) in the area of coated edge section 110 and
non-coated section 113 of fabric 103 adjacent to it. It is evident
that the coating forms a film which fully covers threads 104, 105
in the coated edge area 110 and which connects threads 104, 105
with each other at thread crossing points 117.
[0057] FIG. 5 shows a device for the production of an inventive
clothing. Here, a continuous basic structure in the embodiment of,
for example, fabric 203 is stretched between two rolls 204, 205
which are positioned parallel to each other. Prior to the
application of coating 206 fabric 203 is pre-treated by way of
atmospheric pressure plasma which is produced by plasma nozzle 207.
Applicator roll 209 is used to apply polyurea coating 206 with
which the polyurea which was dissolved in an organic solvent is
applied onto fabric 203. After the application of the coating
material the coating material is, for example, subjected to a heat
treatment by way of dryer 208, causing it to harden or cross-link
and forming the coating.
[0058] While this present 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.
* * * * *