U.S. patent application number 12/673369 was filed with the patent office on 2011-05-05 for seamed press felt of multilayered base-fabric structure for papermaking and process for producing the same.
This patent application is currently assigned to ICHIKAWA CO., LTD.. Invention is credited to Yasuyuki Ogiwara.
Application Number | 20110100576 12/673369 |
Document ID | / |
Family ID | 40350689 |
Filed Date | 2011-05-05 |
United States Patent
Application |
20110100576 |
Kind Code |
A1 |
Ogiwara; Yasuyuki |
May 5, 2011 |
SEAMED PRESS FELT OF MULTILAYERED BASE-FABRIC STRUCTURE FOR
PAPERMAKING AND PROCESS FOR PRODUCING THE SAME
Abstract
A single-seam felt which employs a base fabric of a multilayer
structure and which, despite this, is excellent in wet-web surface
smoothness and has satisfactory batt adhesion. It is free from wrap
protrusion and weft fraying in the seamed part of the layered base
fabric.
Inventors: |
Ogiwara; Yasuyuki; (Tokyo,
JP) |
Assignee: |
ICHIKAWA CO., LTD.
Tokyo
JP
|
Family ID: |
40350689 |
Appl. No.: |
12/673369 |
Filed: |
August 8, 2008 |
PCT Filed: |
August 8, 2008 |
PCT NO: |
PCT/JP08/64274 |
371 Date: |
February 12, 2010 |
Current U.S.
Class: |
162/289 ; 139/11;
139/383A; 28/103 |
Current CPC
Class: |
D21F 7/083 20130101 |
Class at
Publication: |
162/289 ; 28/103;
139/11; 139/383.A |
International
Class: |
D21G 9/00 20060101
D21G009/00; D04H 5/02 20060101 D04H005/02; D03D 41/00 20060101
D03D041/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 10, 2007 |
JP |
2007-210505 |
Claims
1. Seamed papermaking press felt comprising a woven base material
having seam loops at both ends and a batt layer, wherein said base
material comprises a first base fabric having seam loops at both
ends which is joined into an endless form by passing a pintle wire
through said seam loops and one or more second base fabric(s)
having seam loops at both ends, through which a pintle wire is not
passed, which is (are) stacked onto said first base fabric, said
batt layer, which is disposed at least on the wet paper side of
said base material and is entangled with said base material, is cut
in the widthwise direction in the vicinity of the seam loop part of
said second base fabric.
2. Seamed papermaking press felt according to claim 1, wherein the
weight per area unit of the second base fabric is lower than the
weight per area unit of the first base fabric.
3. Seamed papermaking press felt according to claim 1, wherein the
opening formed by the seam loops of the second base fabric is
smaller than the opening formed by the seam loops of the first base
fabric.
4. Seamed papermaking press felt according to claim 1, wherein the
loop length and loop height of the seam loops of the second basic
fabric are respectively smaller than the loop length and loop
height of the first base fabric.
5. Seamed papermaking press felt according to claim 1, wherein, in
the vicinity of the seam loop part of the second base fabric, yarns
are further disposed to reduce the opening formed by the seam loop
of the second base fabric.
6. Seamed papermaking press felt according to claim 5, wherein the
yarns are multi-filaments, bulky yarns or spun yarns.
7. A kit comprising a seamed papermaking press felt, which
comprises a woven base material having seam loops at both ends and
a batt layer, and only one pintle wire to be passed through the
seam loops, wherein said base material comprises a first base
fabric having seam loops at both ends and one or more second base
fabric(s) having seam loops at both ends which is (are) stacked
onto said first base fabric, said batt layer, which is attached by
entanglement at least to the wet paper side of said base material,
is cut in the widthwise direction at the seam loop part of said
second base fabric or in the vicinity thereof, said pintle wire
joins said first base fabric into an endless form on the
papermaking machine by being passed through the seam loops of said
first base fabric.
8. A method for producing a seamed papermaking press felt
comprising a woven base material having seam loops at both ends and
a batt layer, comprising a process for making said base material by
stacking one or more second base fabric(s) having seam loops at
both ends onto a first base fabric having seam loops at both ends,
a process for making endless forms by joining the seam loops of one
end of said first base fabric with the seam loops of the other end
via a pintle wire and by joining the seam loops of one end of said
second base fabric with the seam loops of the other end via a
pintle wire, a process for entangling a batt layer with said base
material by disposing it on the wet paper side of said base
material which comprises said first base fabric and said second
base fabric which have been made into endless forms, a process for
making open-ended forms of said first base fabric and said second
base fabric by withdrawing the pintle wires from the seam loops of
both said first base fabric and said second base fabric, a process
for making an open-ended felt by cutting said batt layer in the
widthwise direction at the seam loop part of said second base
fabric or in the vicinity thereof, and a process for making an
endless form on the papermaking machine by re-inserting a pintle
wire only into said first base fabric.
9. A method for producing a seamed papermaking press felt according
to claim 8, further comprising a process for weaving yarns in the
vicinity of the seam loop part of said second base fabric, when
said second base fabric is woven, to reduce the opening formed by
the seam loops of said second base fabric.
10. A method for producing a seamed papermaking press felt
according to claim 8, further comprising a process for inserting
yarns in the vicinity of the seam loop part of said second base
fabric, after weaving the second base fabric and before entangling
the batt part with the base material, to reduce the opening formed
by the seam loops of said second base fabric.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a seamed papermaking press
felt with a multilayer base fabric structure, which is a felt used
in a press part of a papermaking machine, and a method for
producing the same.
PRIOR ART
[0002] In recent years, as a result of the increase in operating
speed so as to improve productivity, felts with a base fabric of a
thick and hard multilayer structure have come to be used in the
press part of papermaking machines. This improves wear resistance
and dewatering capability during high speed operation and
facilitate the installing operations onto the papermaking machine
by means of an open-ended type constitution in which seams are
formed at both end edges of the base fabric.
[0003] Conventional seamed felts, which have seam loops at both
ends, are made into an endless form by interdigitating said seam
loops with one another after passing them between the rolls of the
papermaking machine and joining them by passing a pintle wire
through the common hole thus formed. Due to adopting a multilayer
structure base fabric it is possible to obtain high quality seamed
felts of a greater void volume than with seamed felts of a single
base fabric, which are suitable for parts with high dewatering
volume and parts with high nip pressure.
[0004] This type of seamed felt is made into an open-ended form by
joining a base fabric having seam loops into an endless form via a
pintle wire passed through the seam loops, by using this as a lower
fabric on the external circumference of which one or more layers of
an upper fabric made from a base fabric without seam loops is (are)
superposed, by attaching the upper fabric with the lower fabric by
needling after posing a batt material on the external circumference
of the upper fabric, and by thereafter cutting the upper fabric in
the widthwise direction at the seam loop part of the lower fabric
or in the vicinity thereof.
[0005] However, when cutting the upper fabric in the widthwise
direction, there is the problem that the warp yarns constituting
the base fabric will fray at the cut part and that the weft yarns
of the upper fabric will come loose at the end parts. Such frayed
or loose yarns in the felt surface have a negative effect on the
quality and operability of paper since they can cause markings and
holes in the wet paper; there are even cases in which the paper is
ruptured.
[0006] In order to solve the above-mentioned problems, measures for
preventing the fraying or loosening of yarns at the cut part of the
cut upper fabric have been devised in the prior art.
[0007] In patent documents 1 and 2, heat melt fibers of a low
melting point material are used for the yarns constituting the
upper fabric, and the crossing points are stuck to each other
(refer to patent document 1, FIG. 5). Moreover, the use, in the
lowest layer of the base fabric (the opposite side of the wet
paper), of a greater number of weft yarns than of warp yarns
(patent document 3), the formation of an area without weft yarns in
the cut part (patent document 4), the use of multiple layers (at
least two layers) in a base fabric having seam loops in which, by
offsetting the seam part, the base fabric (i.e., the weft yarns) is
not cut (patent document 5), and other technologies have been
proposed.
[0008] Even though it is possible to obtain the effect of
preventing the yarns from fraying and loosening by these means to
some extent, only insufficient effect is achieved under severe
conditions. With the technology according to patent documents 2
through 4, which cannot withstand the severe conditions of the
repeated compression occurring in the press part of a papermaking
machine and the changes in tension before and after pressing, the
base fabric tissue will come loose at the cut part. With the
technology according to patent document 5, in which there is an
area without weft yarns, there is further problems that the
adhesion of the batt in this area is bad and that fiber loss and
wear of the felt in this area will be accelerated.
[0009] With the technology according to patent document 5, seam
loops are also formed in the base fabric on the wet paper
contacting side. Yarns need to have sufficient strength to form
seam loops, which means that yarns of a big diameter have to be
used; however, base fabrics woven with yarns of a big diameter have
a rough surface, which causes the wet paper to have a bad surface
smoothness, and since the adhesion of the batt is also bad, fibers
are easily lost and the felt is quickly worn. Moreover, due to a
plurality of seam parts, only inferior seaming operations during
installation are achieved. [0010] [Patent Document 1] JP, A,
11-100787 [0011] [Patent Document 2] JP, A, 2003-96685 [0012]
[Patent Document 3] U.S. Pat. No. 4,863,786 [0013] [Patent Document
4] JP, A, 2004-36020 [0014] [Patent Document 5] Canadian Patent
2229121
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0015] The object of the present invention, after reflecting upon
the above-mentioned problems, in particular the use of felts using
a base fabric of a thick and hard multilayer structure that
resulted from the increase in operating speed, is to provide a
single seam felt, for excellent surface smoothness of the wet
paper, having good adhesion to the batt, and wherein, at the seam
part of the stacked base fabric, the warp yarns do not fray and the
weft yarns do not come loose.
Means for Solving the Problems
[0016] The present invention essentially relates to a seamed
papermaking press felt with a multilayer base fabric structure and
is based on the technologies hereinafter.
(1) Seamed papermaking press felt comprising a woven base material
having seam loops at both ends and a batt layer, wherein
[0017] said base material comprises a first base fabric having seam
loops at both ends which is joined into an endless form by passing
a pintle wire through said seam loops and one or more second base
fabric(s) having seam loops at both ends, through which a pintle
wire is not passed, which is (are) stacked onto said first base
fabric,
[0018] said batt layer, which is disposed at least on the wet paper
side of said base material and is entangled with said base
material, is cut in the widthwise direction in the vicinity of the
seam loop part of said second base fabric.
(2) Seamed papermaking press felt wherein the weight per area unit
of said second base fabric is lower than the weight per area unit
of said first base fabric. (3) Seamed papermaking press felt
wherein the opening formed by the seam loops of said second base
fabric is smaller than the opening formed by the seam loops of said
first base fabric. (4) Seamed papermaking press felt wherein the
loop length and loop height of the seam loops of said second basic
fabric are respectively smaller than the loop length and loop
height of said first base fabric. (5) Seamed papermaking press felt
wherein, in the vicinity of the seam loop part of said second base
fabric, yarns are further disposed to reduce the opening formed by
the seam loop of said second base fabric. (6) Seamed papermaking
press felt wherein said yarns are multi-filaments, bulky yarns or
spun yarns. (7) A kit comprising a seamed papermaking press felt,
which comprises a woven base material having seam loops at both
ends and a batt layer, and only one pintle wire to be passed
through the seam loops, wherein
[0019] said base material comprises a first base fabric having seam
loops at both ends and one or more second base fabric(s) having
seam loops at both ends which is (are) stacked onto said first base
fabric,
[0020] said batt layer, which is attached by entanglement at least
to the wet paper side of said base material, is cut in the
widthwise direction at the seam loop part of said second base
fabric or in the vicinity thereof,
[0021] said pintle wire joins said first base fabric into an
endless form on the papermaking machine by being passed through the
seam loops of said first base fabric.
(8) A method for producing a seamed papermaking press felt
comprising a woven base material having seam loops at both ends and
a batt layer, comprising
[0022] a process for making said base material by stacking one or
more second base fabric(s) having seam loops at both ends onto a
first base fabric having seam loops at both ends,
[0023] a process for making endless forms by joining the seam loops
of one end of said first base fabric with the seam loops of the
other end via a pintle wire and by joining the seam loops of one
end of said second base fabric with the seam loops of the other end
via a pintle wire,
[0024] a process for entangling a batt layer with said base
material by disposing it on the wet paper side of said base
material which comprises said first base fabric and said second
base fabric which have been made into endless forms,
[0025] a process for making open-ended forms of said first base
fabric and said second base fabric by withdrawing the pintle wires
from the seam loops of both said first base fabric and said second
base fabric,
[0026] a process for making an open-ended felt by cutting said batt
layer in the widthwise direction at the seam loop part of said
second base fabric or in the vicinity thereof, and
[0027] a process for making an endless form on the papermaking
machine by re-inserting a pintle wire only into said first base
fabric.
(9) A method for producing a seamed papermaking press felt, further
comprising a process for weaving yarns in the vicinity of the seam
loop part of said second base fabric, when said second base fabric
is woven, to reduce the opening formed by the seam loops of said
second base fabric. (10) A method for producing a seamed
papermaking press felt, further comprising a process for inserting
yarns in the vicinity of the seam loop part of said second base
fabric, after weaving the second base fabric and before entangling
the batt part with the base material, to reduce the opening formed
by the seam loops of said second base fabric.
ADVANTAGES OF THE INVENTION
[0028] According to the present invention, it is possible to
provide a single seam felt for excellent surface smoothness of the
wet paper, having good adhesion to the batt, and wherein, at the
seam part of the stacked base fabric, the warp yarns do not fray
and the weft yarns do not come loose.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 An enlarged sectional view of a felt according to the
present invention at the seam loop part and the vicinity thereof
before the felt is cut in the widthwise direction at the seam part
or the vicinity thereof.
[0030] FIG. 2 An enlarged sectional view of a felt according to the
present invention at the seam loop part and the vicinity thereof
when the felt is cut in the widthwise direction at the seam part or
the vicinity thereof.
[0031] FIG. 3 An enlarged sectional view of a felt according to the
present invention at the seam loop part and the vicinity thereof
after installing on a papermaking machine wherein the felt is cut
in the widthwise direction at the seam part or the vicinity
thereof.
[0032] FIG. 4 A view of a felt according to the present invention
in which yarns are disposed in the vicinity of the seam loop part
of the second base fabric.
[0033] FIG. 5 A view of the prior art.
[0034] FIG. 6 A illustrative diagram of a marking test.
[0035] FIG. 7 A illustrative diagram of a wear test used for
measuring the amount of lost fibers.
EXPLANATION OF THE SYMBOLS
[0036] 1: Felt according to the present invention [0037] 10: First
base fabric [0038] 11: Warp yarn of the first base fabric [0039]
12: Weft yarn of the first base fabric [0040] 13: Pintle wire of
the first base fabric [0041] 1L: Seam loops of the first base
fabric [0042] 1LL: Loop length of seam loops of the first base
fabric [0043] 1LH: Loop height of seam loops of the first base
fabric [0044] 20: Second base fabric [0045] 21: Warp yarn of the
second base fabric [0046] 22: Weft yarn of the second base fabric
[0047] 23: Pintle wire of the second base fabric [0048] 2L: Seam
loops of the second base fabric [0049] 2LL: Loop length of the
second base fabric [0050] 2LH: Loop height of the second base
fabric [0051] 30: Batt layer [0052] 40: Cut part
PREFERRED EMBODIMENTS OF THE INVENTION
[0053] The fiber materials used for the yarns constituting the base
fabrics and for the batt layer in the present invention, which can
be those that are generally used for the press felts of papermaking
machines, are appropriately be selected from such fiber materials
as nylon, polyester, polypropylene, natural materials.
[0054] A batt layer is disposed at least on the wet paper side of a
base material comprising the first base fabric and one or more
second base fabric (s) and is attached to said base material by
entanglement with such treatment as needling or fluid
entanglement.
[0055] Moreover, the present invention is not limited to providing
a batt layer only on the wet paper side of the second base fabric;
a batt layer can also be disposed on the machine side (roller side)
of the first base fabric.
[0056] Furthermore, even if the batt layer is disposed only on the
wet paper side of the second base fabric, the batt fibers may
penetrate to the machine side of the first base fabric when
needling is performed.
[0057] When a batt layer (batt fibers) is disposed on the machine
side of the first base layer, the batt fibers in the vicinity of
the seam loops (1L) of the first base fabric may be removed in the
widthwise direction.
[0058] Moreover, yarns that will swell when the press felt is used
may be inserted in the vicinity of the seam loop part of the second
base fabric so as to reduce the opening formed by the seam loops of
the second base fabric, and to improve the adhesion of the batt and
to ameliorate marking. For these yarns, materials with a prescribed
moisture percentage of 4.5% or more, e.g. very hydrophilic
materials that have the ability to absorb more water content such
as nylon, vinylon, acetate, rayon, polynosic, cupra, cotton, hemp,
silk, wool, etc. can be used; multi-filaments, bulky yarns and spun
yarns made from a tow of 1500 to 1600 dtex are preferably used.
[0059] Next, embodiments of the present invention will be explained
by referring to the drawings.
[0060] FIG. 1 shows felt (1) in the attached state in which a batt
layer (30) is entangled with a base material comprising a first
base fabric (10) and a second base fabric (20), wherein said batt
layer is stacked at least onto the wet paper side of the second
base fabric.
[0061] This attached felt is produced by abutting the seam loops of
the first base fabric having seam loops (1L) at both ends and the
second base fabric having seam loops (2L) at both ends so that the
respective seam loops interdigitated with one another, by joining
said seam loops into endless forms via pintle wires (13), (23)
passed through the respective common holes thus formed, and by
thereafter entangling both with the batt layer.
[0062] After attaching the felt (1) as described above, the pintle
wires (13), (23) are once withdrawn and the batt layer (30) is cut
in the widthwise direction at the seam loop (2L) part of the second
base fabric or in the vicinity thereof (FIG. 2). In this way, the
cut part of the batt layer can be formed on the side of wet paper
without injuring the seam loops.
[0063] By forming the cut part (40) the felt (1) becomes an
open-ended form which is joined into an endless form by passing the
pintle wire (13) through only the seam loops (1L) of the first base
fabric (10) after passing them between the rolls of a papermaking
machine. Then, a pintle wire is not inserted into the seam loops
(2L) of the second base fabric (20) (FIG. 3). Thus, the felt of the
present invention is made up.
[0064] Furthermore, by disposing yarns that will swell when the
press felt is used in the vicinity of the seam loop part of the
second base fabric (20) as weft yarns, it is possible to reduce the
opening formed by the seam loops of the second base fabric, improve
the adhesion of the batt and ameliorate marking.
[0065] The yarns disposed in the vicinity of the seam loop part
(outside the seam loops) of the second base fabric can be disposed
by weaving yarns different from the fabric when weaving the second
base fabric or by inserting into the opening in the vicinity of the
seam loop part (outside the seam loops) with a music wire etc.
after weaving and before the base material is entangled with the
batt part.
[0066] The first base fabric and the second base fabric of the
present invention are preferably woven fabrics woven with a warp
double weave. Furthermore, woven fabrics with a weight per area
unit in the range of 300 to 700 g/m.sup.2, preferably 450 to 650
g/m.sup.2, for the first base fabric, and 100 to 500 g/m.sup.2,
preferably 200 to 400 g/m.sup.2, for the second base fabric, can be
used as base fabric of the present invention.
[0067] Moreover, in the present invention, it is preferred that the
opening formed by the seam loops of the first base fabric is 0.24
to 1.86 mm.sup.3 per loop and the opening formed by the seam loops
of the second base fabric is 0.14 to 0.84 mm.sup.3 per loop. It is
further preferred in the present invention that the first base
fabric has a loop length of 1.50 to 3.00 mm and a loop height of
0.50 to 1.50 mm and that the second base fabric has a loop length
of 1.50 to 2.50 mm and a loop height of 0.50 to 1.00 mm. These
dimensions can be measured by an optical microscope.
Examples
[0068] The seamed papermaking felts of Examples 1, 2 and
Comparative Examples 1 through 3 were made by using the fabrics
shown in Table 1. The materials used are as follows:
Base fabric material: nylon Batt material: nylon, size 39 dtex
Front batt amount: 500 g/m.sup.2 Back batt amount: 200 g/m.sup.2
Inserted yarns: 1500 dtex multifilament yarn (made by Toray
Monofilament Co., Ltd., product number: 1450T-68-3158)
TABLE-US-00001 TABLE 1 First base fabric (lower fabric) Second base
fabric (upper fabric) Weave Weave Yarn used structure Yarn used
structure Example 1 warp 1000 d yarn 84 f/5 cm warp double warp
1000 d yarn 40 f/5 cm warp double Without inserted yarns in the
weft 1240 d yarn 80 f/5 cm weave weft 3/330 d yarn 40 f/5 cm weave
vicinity of the seam loop part Example 2 warp 1000 d yarn 84 f/5 cm
warp double warp 1000 d yarn 40 f/5 cm warp double With inserted
yarns in the weft 1240 d yarn 80 f/5 cm weave weft 3/330 d yarn 40
f/5 cm weave vicinity of the seam loop part Comparative warp 1000 d
yarn 84 f/5 cm warp double warp 1000 d yarn 40 f/5 cm warp double
Without seam loops, Example 1 weft 1240 d yarn 80 f/5 cm weave weft
3/330 d yarn 40 f/5 cm weave slitting after joining Comparative
warp 1000 d yarn 84 f/5 cm warp double warp Without second base
fabric Example 2 weft 1240 d yarn 80 f/5 cm weave weft Comparative
warp 1000 d yarn 84 f/5 cm warp double warp 1000 d yarn 84 f/5 cm
warp double Same as first base fabric Example 3 weft 1240 d yarn 80
f/5 cm weave weft 1240 d yarn 80 f/5 cm weave
[0069] The evaluation tests hereinafter were conducted with the
samples produced according to Examples 1, 2 and Comparative
Examples 1 through 3. The evaluated items adopted in the present
invention were the time until loosening of the second base fabric
(upper fabric) occurred, the marking properties, the amount of lost
fibers, the time required for the seaming process. The results are
shown in Table 2.
Time Until Loosening of the Second Fabric (Upper Fabric)
Occurred
[0070] The time until loosening occurred was measured by a high
speed--high pressure papermaking test. The test conditions were as
follows, papermaking speed: 1000 m/min, applied pressure: 100
kg/cm, HPS (high pressure shower): 15 kg/cm.sup.2.
Marking Properties
[0071] The marking properties were evaluated by marking test using
the device according to FIG. 6. In the test, felt, carbon paper,
paper, batt were superposed and pressed by rolls (applied pressure:
30 kg/cm). The batt was added by 100 gsm (gram per square meter).
The value of 1 part of 1000 of the batt weight was taken as marking
index by which it was confirmed by visual observation that a base
fabric marking was not transferred to the paper. The smaller the
marking index the better the marking properties.
Amount of Lost Fibers
[0072] Evaluation was made by wear test according to Japanese
Industrial Standard (JIS II) using the device of FIG. 7. The test
conditions were as follows: The amount of worn fibers was measured
by electronic scales after 400 slides at a frequency of 30 slides
per minute. Sliding distance: 100 mm, wear terminal area:
20.times.20 mm, applied weight of wear terminal: 500 g, and
sandpaper with a grit of 320 was used.
Seaming Time
[0073] The time required for seaming 1 m on a flat surface was
evaluated.
TABLE-US-00002 TABLE 2 Evaluated items Time until loosening Mark-
Amount of the second base ing of lost Seaming fabric (upper fabric)
index fibers time Example 1 No loosening after 1000 0.6 60 mg 60
s/m hours Example 2 No loosening after 1000 0.5 60 mg 60 s/m hours
Comparative Loosening after 300 0.6 70 mg 60 s/m Example 1 hours
Comparative . . . 1.2 160 mg 60 s/m Example 2 Comparative No
loosening after 1000 1.2 80 mg 150 s/m Example 3 hours
[0074] The results of the evaluation tests, as shown in Table 2,
demonstrate that, in Examples 1 and 2, there was no loosening of
the second base fabric, or only after a very long period of time.
The marking index was also small and the marking properties were
good. The loss of fibers was small and there was a good resistance
to fiber loss. Further, the seaming time was short, whereby a
reduction of the time for installing onto the papermaking machine
can be expected.
INDUSTRIAL APPLICABILITY
[0075] According to the present invention it is possible to obtain,
even when a base fabric of a multilayer structure is used, a single
seam felt for excellent surface smoothness of the wet paper, having
good batt adhesion, and wherein, at the seam part of the stacked
base fabric, the warp yarns do not fray and the weft yarns do not
come loose.
[0076] This felt is particularly useful, even when using base
fabrics of a thick and hard multilayer structure that have come
into use as a result of the increase in operating speed, to
increase wear resistance and dewatering capability during high
speed operation, to obtain excellent surface smoothness of the wet
paper surface and durability, and to facilitate the installing
operations.
* * * * *