U.S. patent application number 12/823690 was filed with the patent office on 2011-10-20 for papermaking press felt and papermaking method.
This patent application is currently assigned to Ichikawa Co., Ltd.. Invention is credited to Hirofumi MURAKAMI, Hiroyuki ODA, Takashi OUCHI, Yuya TAKAMORI, Takao YAZAKI.
Application Number | 20110253328 12/823690 |
Document ID | / |
Family ID | 43501429 |
Filed Date | 2011-10-20 |
United States Patent
Application |
20110253328 |
Kind Code |
A2 |
YAZAKI; Takao ; et
al. |
October 20, 2011 |
PAPERMAKING PRESS FELT AND PAPERMAKING METHOD
Abstract
The object of the invention is to provide a papermaking felt
which can be easily engaged in a papermaking machine, wherein the
work time for engaging the felt is short, the initial warming-up
period until reaching the highest papermaking speed is short, and
the felt life is long. This object is achieved by integrating and
attaching by dispersion in the batt layer of the felt a polymeric
elastomer having high deformability when pressure is applied and
good recoverability after pressure is applied. When said polymeric
elastomer is in the form of a film and when measured at a room
temperature of 20.degree. C. and a relative humidity of 65%, the
100% modulus value of the film is 1 to 100 kg/cm.sup.2, the
residual strain after 100% elongation is 30% or less, and the
attached amount of polymeric elastomers is 0.5 to 20 wt. % of the
papermaking press felt weight. Examples of materials include
polyurethane elastomers, polyethylene elastomers, styrene-butadiene
rubber, silicone rubber, or the like.
Inventors: |
YAZAKI; Takao; (Tokyo,
JP) ; OUCHI; Takashi; (Tokyo, JP) ; ODA;
Hiroyuki; (Tokyo, JP) ; MURAKAMI; Hirofumi;
(Tokyo, JP) ; TAKAMORI; Yuya; (Tokyo, JP) |
Assignee: |
Ichikawa Co., Ltd.
14-15, Hongo 2-chome, Bunkyo-ku
Tokyo
JP
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20110108224 A1 |
May 12, 2011 |
|
|
Family ID: |
43501429 |
Appl. No.: |
12/823690 |
Filed: |
June 25, 2010 |
Current U.S.
Class: |
162/100;
162/289 |
Current CPC
Class: |
D21F 7/083 20130101 |
Class at
Publication: |
162/100;
162/289 |
International
Class: |
D21H 23/00 20060101
D21H023/00; D21G 9/00 20060101 D21G009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 10, 2009 |
JP |
2009-257389 |
Claims
1. Papermaking press felt comprising a reinforcing fiber base
material and batt layers provided on both the wet paper web
carrying side and the press roll side of said reinforcing fiber
base material or a batt layer provided only on the wet paper web
carrying side of said reinforcing fiber base material; wherein a
polymeric elastomer is dispersedly attached to the batt layer
inside the felt on the wet paper web carrying side of the felt;
wherein, when said polymeric elastomer is in the form of a film and
when measured at a room temperature of 20.degree. C. and a relative
humidity of 65%, the 100% modulus value of the film is 1 to 100
kg/cm.sup.2, the residual strain after 100% elongation is 30% or
less, and the attached amount of polymeric elastomers is 0.5 to 20
wt. % of the papermaking press felt weight.
2. Papermaking press felt according to claim 1; wherein the
polymeric elastomer comprises one or more members selected from the
group consisting of natural rubber, isoprene rubber, 1,4-butadiene
rubber, 1,2-butadiene rubber, styrene-butadiene copolymer rubber,
chloroprene rubber, nitrile rubber, butyl rubber,
ethylene-propylene copolymer rubber, ethylene-propylene-butadiene
copolymer rubber, ethylene-propylene-ethylidene norbornene
copolymer rubber, chlorosulfonated polyethylene elastomer, acrylic
rubber, epichlorohydrine rubber, polysulfide rubber, silicone
rubber, fluoro rubber, polyurethane elastomer, polyolefin elastomer
in which the above-mentioned rubbers or ethylene-vinyl acetate
copolymers have been blended with polyethylene, polyamide
elastomer, polyester elastomer, polystyrene elastomers selected
from the group consisting of styrene-butadiene-styrene-copolymer
elastomer, styrene-ethylene-butylene-styrene copolymer elastomer,
acrylonitrile-butadiene-styrene copolymer elastomer or hydrogenated
products thereof, and plasticized vinyl chloride resin.
3. Papermaking method using a papermaking press felt according to
claim 1.
4. Papermaking method using a papermaking press felt according to
claim 2.
5. Papermaking method using a papermaking press felt according to
claim 1, wherein batt layers are provided on both the wet paper web
carrying side and the press roll side of said reinforcing fiber
base material.
6. Papermaking method using a papermaking press felt according to
claim 1, wherein a batt layer is provided only on the wet paper web
carrying side of said reinforcing fiber base material.
7. Papermaking method using a papermaking press felt according to
claim 2, wherein batt layers are provided on both the wet paper web
carrying side and the press roll side of said reinforcing fiber
base material.
8. Papermaking method using a papermaking press felt according to
claim 2, wherein a batt layer is provided only on the wet paper web
carrying side of said reinforcing fiber base material.
9. Papermaking method using a papermaking press felt according to
claim 1, wherein the polymeric elastomer is foamed or partially
cross-linked.
10. Papermaking method using a papermaking press felt according to
claim 2, wherein the polymeric elastomer is foamed or partially
cross-linked.
11. Papermaking method using a papermaking press felt according to
claim 1, wherein the polymeric elastomer further comprises at least
one inorganic filler or at least one thermal stabilizer, or at
least one inorganic filler and at least one thermal stabilizer.
12. Papermaking method using a papermaking press felt according to
claim 1, wherein the polymeric elastomer further comprises at least
one inorganic filler or at least one thermal stabilizer, or at
least one inorganic filler and at least one thermal stabilizer.
13. Papermaking method using a papermaking press felt according to
claim 1, wherein the 100% modulus value of the film is 1 to 70
kg/cm.sup.2.
14. Papermaking method using a papermaking press felt according to
claim 1, wherein the residual strain after 100% elongation is 20%
or less.
15. Papermaking method using a papermaking press felt according to
claim 1, wherein the 100% modulus value of the film is 1 to 70
kg/cm.sup.2.
16. Papermaking method using a papermaking press felt according to
claim 1, wherein the residual strain after 100% elongation is 20%
or less.
Description
[0001] The present invention relates to a papermaking press felt
(also called "press fabric") used in a papermaking machine. In
greater detail, the present invention relates to a papermaking
press felt (hereinafter also simply called "felt") having good
water squeezing capability of the wet paper web wherein, when a new
papermaking press felt is installed in a papermaking machine, the
period of time is shortened which is required for gradually
increasing the papermaking speed from immediately after the start
of the papermaking operation until the highest papermaking speed is
reached (this period is called the initial warming-up period), and
wherein the operation of the papermaking machine is stabilized.
BACKGROUND ART
[0002] Conventionally, papermaking machines in the papermaking
process are generally equipped with a wire part, a press part and a
dryer part to dewater wet paper webs. These parts are provided in
the direction in which the wet paper web is transferred in the
order of: wire part, press part and dryer part. The wet paper web
is squeezed and dewatered and, at the same time, transferred while
being passed from one papermaking equipment to the next provided in
the wire part and press part, respectively, to be finally dried in
the dryer part.
[0003] In these parts, papermaking equipment is used which
corresponds to the functions of dewatering the wet paper web (wire
part), squeezing water from the wet paper web (press part) and
drying the wet paper web (dryer part). Moreover, the press part is
generally equipped with one or more press devices arranged in
series in the direction in which the wet paper web is
transported.
[0004] Each press device comprises an endless felt (closed type) or
an open-ended felt that has been formed into an endless felt by
connecting it in the papermaking machine. Each press device also
comprises a pair of rolls, which face each other (i.e. a roll
press), or a roll and a shoe, which face each other (i.e. a shoe
press); the wet paper web is placed on the felt, and, while it is
moving together with the felt in the wet paper web conveyance
direction, moisture is squeezed from the wet paper web by pressing
the wet paper web together with the felt in the roll press or in
the shoe press; the moisture pressed from the wet paper web is
continuously absorbed by the felt or passes through the felt to be
drained to the outside of the felt.
[0005] Hereinafter, one example of the press part of a papermaking
machine will be described in detail with reference to FIG. 1. The
papermaking parts are arranged in the wet paper web conveyance
direction in the order of wire part, which is the fore-part in the
papermaking process, press part positioned thereafter, and dryer
part positioned after the press part. This press part is of a
typical transfer twinbar type papermaking machine and comprises 4
press devices; the press devices: No. 1 press device (1P) formed by
a top roll 1a and a bottom roll 1b, No. 2 press device (2P) formed
by a No. 2 roll and a center roll (CR), No. 3 press device (3P)
formed by a No. 3 roll and the center roll (CR), and No. 4 press
device (4P) formed by a top roll 4a and a bottom roll 4b,
respectively, are provided next to each other in series in the wet
paper web conveyance direction. Moreover, there are also
papermaking machines in which, in the press devices, either the top
rolls (1a or 4a) or the bottom rolls (1b or 4b) are configured as a
shoe press device, or in which roll 3 is configured as a shoe press
device.
[0006] The above-mentioned transfer twinbar type papermaking
machines use a plurality of papermaking felts (4 felts in FIG. 1).
Normally, the felts used are a pickup felt (PU felt) for receiving
the wet paper web from the wire part, a pickup felt used on the top
roll side of the No. 1 press device (1P), a 1P bottom felt used on
the bottom roll side, a 3P felt used in the No. 3 press device
(3P), and a 4P felt used in the No. 4 press device (4P). The pickup
felt serves for a felt used in the No. 2 press device (2P).
[0007] The above-mentioned felts are made from a reinforcing fiber
base material 5 and batt layers 6, 7 as shown in FIG. 2 or 3; a
batt layer is provided on both the wet paper web carrying side and
the press roll side of the reinforcing fiber base material, or only
on the wet paper web carrying side. The batt layers 6, 7 are made
by intertwiningly integrating short fibers (staple fibers), from
which the batt is made, with the reinforcing fiber base material by
needle punching. These felts have the fundamental functions of
squeezing water from the wet paper web (water squeezing
capability), of increasing the smoothness of the wet paper web and
of conveying the wet paper web.
[0008] Of the above-mentioned felt function, particularly the
function of squeezing water from the wet paper web is considered to
be important. The wet paper web is pressure squeezed together with
the felt by passing the pressure position of the roll press or the
shoe press; and after the moisture of the wet paper web has been
transferred to the felt, it is drained outside the felt by the
suction force of a suction box or the pressure of a squeeze press;
therefore, the water permeability for assuring a suitable void
volume in the felt and the ability to maintain compressibility and
recoverability are considered to be important properties.
[0009] The above-mentioned suitable void volume is the void volume
of a felt when the highest papermaking speed has been reached after
it has been gradually increased. In other words, from the viewpoint
of productivity, it is important that the operating speed of a
papermaking machine rapidly reaches the highest papermaking speed
as soon as possible after starting to make paper with a new felt.
The period until the highest papermaking speed is reached (the
initial warming-up period) differs according to the operating
conditions of the papermaking machine; however, in general one to
two days, at most five days, are required. It is particularly
important to shorten the initial warming-up period of the
above-mentioned felts with wet paper conveyance methods such as the
no-draw straight-through method, of which the Tandem-Nipco Flex
Press and OptiPress papermaking machines are representative
examples, because high operating speeds are used.
[0010] Strategies to make the felt thinner and increase the felt
density by applying pressure after the felt has been made have been
used to shorten the initial warming-up period of these felts. There
are also cases in which the felt is brought into contact with a
roll that has been heated by a heating medium in order to increase
the pressing effect of the felt. Due to the operating and the
effect of a high density felt it is possible to facilitate the
transfer of the pressing force received by the felt in the press
part to the wet paper web by reducing the void volume in the
felt.
[0011] In JP, T, 2005-524002 (Patent document 1), a felt and a
production method are disclosed in which the void volume of the
felt surface is reduced and the density is increased by polishing
the felt surface after the felt front side (wet paper web carrying
side) has been treated with a polymer substance. A papermaking felt
of this structure is compacted as a new felt from the beginning
(with an increased density); therefore, when the felt is used in a
papermaking machine, the initial warming-up period is
shortened.
[0012] Nevertheless, even though a papermaking felt using a polymer
of the polymer substances mentioned in Patent document 1, which are
polyurethane, polycarbonate urethane, polyacrylate, acryl resin,
epoxy resin, phenol resin or mixed polymers thereof, can be
compacted due to the adhesive force and the coagulating force of
the polymers, stiffness is given to the felt as a whole. When the
stiffness of a felt increases, the compressibility and
recoverability under the press of a papermaking machine is
suppressed; therefore, there is a loss of the wet paper web water
squeezing performance; moreover, when the papermaking felt is
placed in a papermaking machine, due to the felt stiffness, it is
difficult to place the felt which has to be manually inserted in
the narrow spaces between the rolls inside the papermaking
machine.
[0013] Furthermore, US, A1, No. 2009/0163104 (Patent document 2)
discloses a press fabric (felt), wherein the felt surface is coated
with a polymer dispersion liquid which, by drying, bridges the batt
fiber spaces by covering them with a polymer film (membrane);
moreover, by covering the surroundings of the batt fibers (the
polymer layer thickness is 0.05 mm to 1.5 mm), the polymer membrane
adjusts the void volume and the density of the felt surface layer
without separating from the batt fibers. Examples of polymers
include polyurethane elastomers, polyether-polyamide elastomers,
engineering polyamides (polyamide 11, polyamide 12, polyamide 6.12,
or the like). The blending amount of the polymers in relation to
the felt weight is not disclosed by specific figures.
[0014] This felt is characterized in that the air-permeability is
suitably adjusted and in that it can be subjected to washing by a
high pressure water jet. Nevertheless, even though the initial
warming-up period of the felt can be shortened, there is the
disadvantage that, since the void volume is reduced and the overall
thickness of the felt is thinner, the felt is flattened by the
press pressure repeatedly received during use and rapidly arrives
at the limit of the thickness that can be used, and the period
during which the wet paper web can be sufficiently squeezed (felt
life) is shortened.
CITATION LIST
Patent Literature
[0015] Patent document 1: JP, T, No. 2005-524002 [0016] Patent
document 2: US, A1, No. 2009/0163104
SUMMARY OF INVENTION
Technical Problem
[0017] Compared to conventional felts, wherein the void volume for
transferring mechanical pressure and hydraulic pressure to the
squeezed wet paper web is poor, the object of the present invention
is to provide a felt, wherein a suitable void volume for the
initial warming-up period can be ensured from the start of use, and
wherein the initial warming-up period of the felt can be shortened
to four days or less. Moreover, the present invention also provides
a felt, wherein, if the thickness deformation resistance of the
felt is reduced, pressure density tends to increase when pressure
is applied by the press rolls or the like, recoverability after
pressing is high, accumulation of dirt and excessive flattening are
less likely to occur, and water permeability and compressibility
can be maintained for a long time. To provide such a felt is also
an object of the present invention.
[0018] Specifically, the present invention provides a papermaking
press felt, wherein, by including a polymeric elastomer having
suitable flexibility and good compressibility and recoverability, a
suitable void volume can be assured in the felt, water permeability
and compressibility can be maintained for a long time, the initial
warming-up period of the papermaking press felt is shorter than
that of a conventional felt, the felt life is long, and water
squeezing capability is good.
Solution to Problem
[0019] The invention according to claim 1 provides a papermaking
press felt comprising a reinforcing fiber base material and batt
layers provided on both the wet paper web carrying side and the
press roll side of said reinforcing fiber base material or a batt
layer provided only on the wet paper web carrying side of said
reinforcing fiber base material; wherein a polymeric elastomer is
dispersedly attached to the batt layer inside the felt on the wet
paper web carrying side of the felt; wherein, when said polymeric
elastomer is in the form of a film and when measured at a room
temperature of 20.degree. C. and a relative humidity of 65%, the
100% modulus value of the film is 1 to 100 kg/cm.sup.2, the
residual strain after 100% elongation is 30% or less, and the
attached amount of polymeric elastomers is 0.5 to 20 wt. % of the
papermaking press felt weight.
[0020] The invention according to claim 2 provides a papermaking
felt according to claim 1; wherein the polymeric elastomer
comprises one or more members selected from the group consisting of
natural rubber, isoprene rubber, 1,4-butadiene rubber,
1,2-butadiene rubber, styrene-butadiene copolymer rubber,
chloroprene rubber, nitrile rubber, butyl rubber,
ethylene-propylene copolymer rubber, ethylene-propylene-butadiene
copolymer rubber, ethylene-propylene-ethylidene norbornene
copolymer rubber, chlorosulfonated polyethylene elastomer, acrylic
rubber, epichlorohydrine rubber, polysulfide rubber, silicone
rubber, fluoro rubber, polyurethane elastomer, polyolefin elastomer
in which the above-mentioned rubbers or ethylene-vinyl acetate
copolymers have been blended with polyethylene, polyamide
elastomer, polyester elastomer, polystyrene elastomers selected
from the group consisting of styrene-butadiene-styrene-copolymer
elastomer, styrene-ethylene-butylene-styrene copolymer elastomer,
acrylonitrile-butadiene-styrene copolymer elastomer or hydrogenated
products thereof, and plasticized vinyl chloride resin.
Advantageous Effects of Invention
[0021] With the papermaking press felt according to the present
invention, a suitable void volume for the initial warming-up period
can be ensured from the start of use, and the initial warming-up
period can be shortened. Moreover, the present invention also
provides a felt, wherein, if the thickness deformation resistance
of the felt is reduced, pressure density tends to increase when
pressure is applied by the press rolls or the like, recoverability
after pressing is high, accumulation of dirt and excessive
flattening are less likely to occur, and water permeability and
compressibility can be maintained for a long time. By means of such
a felt, it is possible to obtain a papermaking press felt having a
good balance of the fundamental felt functions such as a
maintainance of the water squeezing capability of the felt, or the
like.
BRIEF DESCRIPTION OF DRAWINGS
[0022] FIG. 1 is a schematic diagram of the press part of a
papermaking machine.
[0023] FIG. 2 is a view showing a state in which the polymeric
elastomer present stays in the front-side batt layer in the
papermaking press felt.
[0024] FIG. 3 is a view showing a state in which the polymeric
elastomer present extends from the front-side batt layer to the
rear-side batt layer in the papermaking press felt.
[0025] FIG. 4 is a schematic diagram of a tensile test.
[0026] FIG. 5 is a schematic diagram of a press tester.
DESCRIPTION OF EMBODIMENTS
[0027] Hereinafter, the present invention will be described in
detail with reference to the drawings.
[0028] The present invention is a press felt for use in the press
part shown in FIG. 1. The press felts according to the present
invention exemplified in FIGS. 2 and 3 comprise a reinforcing fiber
base material 5, a front batt layer 6 provided on the wet paper
carrying side (front side) of said base material, and a rear batt
layer 7 provided on the press roll side (rear side) of said base
material; wherein a polymeric elastomer stays in the front batt
layer 6, or the polymeric elastomer extends from the front batt
layer to the rear batt layer 7, as respectively shown in FIGS. 2
and 3.
[0029] The reinforcing fiber base material 5 generally is a woven
fabric woven from a CMD (Cross Machine Direction) yarn and a MD
(Machine Direction) yarn by a loom or the like; however, a lattice
material obtained by overlapping rows of CMD yarns and MD yarns
without weaving may also be used.
[0030] Examples of materials for the reinforcing fiber base
material, which is made from CMD and MD yarns, and for the batt
include polyesters (polyethylene terephthalate, polybutylene
terephthalate, or the like), engineering polyamides (polyamide 11,
polyamide 12, polyamide 6.12, or the like), aromatic polyamides
(aramide), polyvinylidene difluoride, polypropylene,
polyether-polyester ketone, polytetrafluoroethylene, polyethylene,
cotton, wool, metal, or the like.
[0031] Examples of materials for the polymeric elastomer include
one or more members selected from the group consisting of natural
rubber, isoprene rubber, 1,4-butadiene rubber, 1,2-butadiene
rubber, styrene-butadiene copolymer rubber, chloroprene rubber,
nitrile rubber, butyl rubber, ethylene-propylene copolymer rubber,
ethylene-propylene-butadiene copolymer rubber,
ethylene-propylene-ethylidene norbornene copolymer rubber,
chlorosulfonated polyethylene elastomer, acrylic rubber,
epichlorohydrine rubber, polysulfide rubber, silicone rubber,
fluoro rubber, polyurethane elastomer, polyolefin elastomer in
which the above-mentioned rubbers or ethylene-vinyl acetate
copolymers have been blended with polyethylene, polyamide
elastomer, polyester elastomer, polystyrene elastomers selected
from the group consisting of styrene-butadiene-styrene-copolymer
elastomer, styrene-ethylene-butylene-styrene copolymer elastomer,
acrylonitrile-butadiene-styrene copolymer elastomer or hydrogenated
products thereof, and plasticized vinyl chloride resin.
[0032] FIG. 4 shows the measuring part of a test apparatus used for
measuring the 100% modulus value and the residual strain after 100%
elongation of a polymeric elastomer film. In the 100% modulus value
measurement, JIS K6251-2004 was referred and in the measurement of
the residual strain after 100% elongation, JIS K6262-1997 was
referred, and these tests were performed under the conditions
described hereinafter.
[0033] In both tests, a polymeric elastomer specimen 41 was a film
of 10 mm width, 120 mm length (including 40 mm for the grip on each
side), 40 mm grip distance, and 0.5 mm thickness. The tests were
performed at a room temperature of 20.degree. C. and a relative
humidity of 65%.
[0034] The specimen 41 was set in grips 42, stretched to an
elongation percentage of 110% at a stretching speed of 200 mm/min,
and the stress (kg/cm.sup.2) at an elongation percentage of 100%
was taken as the 100% modulus value.
[0035] Further, the specimen was stretched to an elongation
percentage of 100%, the elongation was reversed at the same speed
the moment after reaching the elongation percentage of 100%, and
the percentage of elongation when the stress reached 0 kg/cm.sup.2
was taken as the residual strain after an elongation of 100%.
[0036] The polymeric elastomer may be foamed or partially
cross-linked. It may further comprise (an) inorganic filler(s) and
(a) thermal stabilizer(s). Examples of foaming agents include
ammonium carbonate, sodium bicarbonate, ammonium bicarbonate,
sodium hydrogencarbonate, or the like and examples of inorganic
fillers include titanium oxide, kaolin, clay, talc, diatomaceous
earth, calcium carbonate, calcium silicate, magnesium silicate,
fused silica, mica, or the like.
[0037] The polymeric elastomer is attached to the short fibers
(staple fibers) constituting the batt by dispersing fragments with
5 .mu.m to 2 mm thickness. It can also be envisioned to use the
short fibers (staple fibers) as the center which becomes a core
around which the polymeric elastomer is coated in the shape of a
sheath with a thickness of 1 to 40 .mu.m. When the polymeric
elastomer is attached to the batt fibers in the shape of fragments
and/or in the shape of a sheath formed around a core, the felt has
good compressibility, recoverability and water squeezing
capability; there is moreover the added advantage that, during the
period of use of the felt, these characteristics can be maintained
for a long time.
[0038] In view of felt compressibility, recoverability and water
squeezing capability, the 100% modulus of the polymeric elastomer
film is 1 to 100 kg/cm.sup.2, and preferably 70 kg/cm.sup.2 or
less. Also in view of felt compressibility, recoverability and
water squeezing capability, the residual strain after 100%
elongation is 30% or less, and preferably 20% or less.
[0039] The amount of attached polymeric elastomer is 0.5 to 20 wt.
% of the papermaking press felt weight. When the amount is less
than 0.5 wt. % of the felt weight, it is not possible to maintain
water permeability and compressibility of the felt for a long time,
which results in a deterioration of the felt durability. If, on the
other hand, the amount is more than 20 wt. % of the felt weight,
felt stiffness is too great and the thickness deformation
resistance cannot be reduced, the pressure density does not easily
increase when pressure is applied by the press rolls or the like,
and the recoverability after pressing can decline.
[0040] The location in which the polymeric elastomer is included in
the papermaking felt is not particularly limited; however,
preferably it is included in the region comprising the reinforcing
fiber base material and the wet paper web carrying side batt layer
(front batt layer). Specifically, it can be included in the wet
paper web carrying side batt layer only, in the region extending
from the wet paper web carrying side batt layer to the press roll
side batt layer (rear batt layer), in the region from the wet paper
web carrying side batt layer to the reinforcing fiber base
material, or in the region from the press roll side batt layer to
the reinforcing fiber base material.
[0041] The polymeric elastomer can be attached (bonded) to the
short fibers (staple fibers) constituting the batt by
coating/impregnating on the felt surface by means of coating,
spraying, blade coating, or the like and, thereafter, drying a
solvent dispersion liquid of the polymeric elastomer.
[0042] The papermaking press felt according to the present
invention should include a void volume (air permeability: 2 to 50
cc/cm.sup.2 sec., 125 Pa) that enables the felt to transmit
mechanical and hydraulic pressure to the squeezed wet paper web. In
other words, the felt should maintain a fixed void volume from the
initial warming-up period to the highest papermaking speed region,
in which the operating speed has stabilized, and until the end of
service is reached.
[0043] The degree of felt hardness (stiffness) of the papermaking
press felt according to the present invention is preferably such
that the felt is easily deformed when pressure is applied by the
press roll, or the like, and the felt density is increased to its
highest limit. To achieve this, the polymeric elastomer included in
the felt has an elasticity expressed by the above-mentioned 100%
modulus and the residual strain after 100% elongation.
EXAMPLES
[0044] Hereinafter, the present invention will be described with
reference to the Examples and Comparative Examples. The present
invention is, however, not limited to these Examples.
Examples 1 to 8 and Comparative Examples 1 and 2
[0045] The basic configuration of the felts used in the Examples
and Comparative Examples was as follows:
Reinforcing fiber base material (nylon monofilament twine, single
weave):
[0046] basis weight 750 g/m.sup.2 Batt fiber (nylon 6 staple fiber
of 17 dtex) [0047] wet paper web carrying side (front batt layer)
of the reinforcing base material: [0048] basis weight 500 g/m.sup.2
[0049] press roll side (rear batt layer) of the reinforcing fiber
base material: [0050] basis weight 250 g/m.sup.2
[0051] After making the felt by stacking and intertwiningly
integrating the rear-side batt fibers and the front-side batt
fibers with the reinforcing fiber base material by needling, the
polymeric elastomer was spray coated from the front side of the
felt, dried at 105.degree. C., and, thereafter, cured at
140.degree. C.
[0052] The polymeric elastomer resins shown in Table 1 were applied
under the conditions given in the same Table. TABLE-US-00001 TABLE
1 Polymeric elastomer film characteristics Felt coating 100% Strain
(%) Attached Foaming modulus after 100% amount Attached Polymeric
elastomer agent Filler (kg/cm.sup.2) elong. (wt. %) shape Example 1
Polyurethane -- -- 2 3 10 sheath elastomer (SUPERFLEX.sup.1))
Example 2 Polyurethane -- -- 70 19 5 sheath elastomer
(Impranil.sup.2)) Example 3 Styrene-butadiene -- -- 8 5 20 sheath
& rubber (Nalstar.sup.3)) fragments Example 4 Silicone rubber
(KE.sup.4)) -- -- 24 15 5 sheath Example 5 Polyethylene -- -- 3 18
5 fragments elastomer (HYTEC.sup.5)) Example 6 Polyurethane -- --
15 11 5 sheath elastomer (EVAFANOL.sup.6)) Example 7 Polyurethane
Hydro- -- 10 8 5 fragments elastomer cerol (EVAFANOL.sup.6)) 10 wt.
% Example 8 Polyurethane -- Kaolin 17 13 5 sheath elastomer 10 wt.
% (EVAFANOL.sup.6)) Comparat. Without resin -- -- -- -- -- --
Example 1 Comparat. Polyurethane -- -- 120 38 5 sheath Example 2
elastomer (ADEKA BONTIGHTER.sup.7)) .sup.1)Daiichi Kogyo Seiyaku
Co., Ltd. .sup.2)Bayer Japan Co., Ltd. .sup.3)Nippon A & L Inc.
.sup.4)Shinetsu Chemical Co., Ltd. .sup.5)Toho Chemical Industry
Co., Ltd. .sup.6)Nicca Chemical Co., Ltd. .sup.7)ADEKA
Corporation
[0053] The press tester shown in FIG. 5 was used to perform running
tests with the felts produced in Examples 1 to 8 and Comparative
Examples 1 and 2 (conditions: 1,000 m/min, 100 KN/m pressure, 100
hours); and the water squeezing capability and the elasticity
maintaining properties of the felts were evaluated.
[0054] When the press tester shown in FIG. 5 is used, a sample of a
felt 10 runs around guide rolls GR while being pressed (squeeze
pressed) by a pair of press rolls PR, PR. In this press tester, the
thickness of the felt 10 before pressing, during pressing and after
pressing can be measured by thickness sensors SE0, SE1 and SE2,
respectively. Moreover, a sample of the wet paper web can be taken
at the entrance of the pair of press rolls PR, PR, the wet paper
web can be recovered at the press exit, and the moisture thereof
can be measured. The test was performed by adjusting the moisture
of the felt by a shower which delivered the moisture.
[0055] The squeezing test of the wet paper web was performed with
the following press tester conditions and formulae:
Squeezing test conditions: pressure=100 KN/m,paper speed=1,000
m/min Moisture content of the wet paper web before pressing: 70
.times. % .times. .times. Moisture .times. .times. content .times.
.times. of .times. .times. the .times. .times. wet .times. .times.
paper .times. .times. web .times. .times. before .times. .times.
pressing = ( wet .times. .times. paper .times. .times. web .times.
.times. weight .times. .times. before .times. .times. pressing -
dried .times. .times. paper .times. .times. weight ) wet .times.
.times. paper .times. .times. weight .times. .times. before .times.
.times. pressing .times. 100 ##EQU1## Moisture .times. .times.
content .times. .times. of .times. .times. the .times. .times. wet
.times. .times. paper .times. .times. web .times. .times. after
.times. .times. pressing = ( wet .times. .times. paper .times.
.times. web .times. .times. weight .times. .times. after .times.
.times. pressing - dried .times. .times. paper .times. .times.
weight ) wet .times. .times. paper .times. .times. weight .times.
.times. after .times. .times. pressing .times. 100 ##EQU1.2##
[0056] The lower the moisture content of the wet paper web after
pressing, the better is the water squeezing capability of the felt.
In the papermaking sector it is understood that, even if the
difference in moisture content of the wet paper web after squeezing
is only 1%, there is a big impact on the amount of thermal energy
required in the paper drying process after pressing.
[0057] The compression test of the felt was performed with the
following press tester conditions and formulae:
In the press tester:
[0058] thickness before pressing: T0 [0059] thickness during
pressing: T1(100 KN/m) [0060] thickness after pressing: T2 [0061]
compression rate during pressing=(T0-T1)/T0.times.100 [0062]
thickness maintaining rate before and after
pressing=T2/T0.times.100
[0063] The results of these tests are shown in Table 2.
TABLE-US-00002 TABLE 2 Evaluation items Properties during running
test Water squeezing capability Ability to maintain elasticity
Moisture content (%) of the wet Compression rate (%) during
Thickness maintaining rate (%) paper web after pressing pressing
before and after pressing after 10 min after 100 h after 10 min
after 100 h after 10 min after 100 h Example 1 48 46 29.6 26.8 85.3
87.5 Example 2 52 50 25.9 22.8 83.5 85.8 Example 3 47 45 27.9 26.3
85.4 87.8 Example 4 51 48 26.3 23.0 84.1 86.4 Example 5 48 47 29.6
24.5 83.5 85.4 Example 6 49 46 28.2 24.4 84.9 87.1 Example 7 49 48
28.9 26.0 85.2 87.2 Example 8 50 48 26.9 24.6 84.4 87.1 Comparat.
56 53 29.7 22.1 81.5 84.3 Example 1 Comparat. 54 52 25.2 22.1 82.9
84.9 Example 2
[0064] Table 2 shows that the smaller the value of the moisture
content of the wet paper web after pressing, the better is the
water squeezing capability, and the bigger the values of
compression rate during pressing (corresponding to the
compressibility of the felt) and the thickness maintaining rate
before and after the pressing (corresponding to the recoverability
of the felt after compression), the better is the ability to
maintain elasticity.
[0065] Examples 1 to 8 show that the capability to squeeze water
from a wet paper web as well as the felt compressibility and
recoverability and the maintaining properties thereof are improved
according to a kind of a polymeric elastomer included.
INDUSTRIAL APPLICABILITY
[0066] The papermaking felt obtained according to the present
invention can improve the capability to squeeze water from a wet
paper web throughout its period of use including the initial
warming-up period until the highest papermaking speed is reached,
at which stable production of a papermaking machine is possible;
and, compared to felts like those in Comparative Example 2 in which
a high modulus resin was used, a felt according to the present
invention can be easily installed in a papermaking machine.
DESCRIPTION SIGN LIST
[0067] 1P to 4P No. 1 press device to No. 4 press device [0068] 1a,
4a Top rolls [0069] 1b, 4b Bottom rolls [0070] CR Center roll
[0071] 2, 3 Rolls [0072] 5 Reinforcing fiber base material [0073]
5a MD yarn [0074] 5b CMD yarn [0075] 6 Front batt layer [0076] 7
Rear batt layer [0077] 8 Polymeric elastomer containing layer
[0078] 10 Felt [0079] 41 Specimen [0080] 42 Grips [0081] GR Guide
rolls [0082] PR Press rolls [0083] SE0 Thickness sensor [0084] SE1
Thickness sensor [0085] SE2 Thickness sensor
* * * * *