U.S. patent application number 16/334110 was filed with the patent office on 2019-08-22 for copper fiber nonwoven fabric.
The applicant listed for this patent is Tomoegawa Co., Ltd.. Invention is credited to Daisuke Muramatsu, Katsuya Okumura, Minoru Tsuchida, Hajime Tsuda.
Application Number | 20190257014 16/334110 |
Document ID | / |
Family ID | 61690439 |
Filed Date | 2019-08-22 |
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United States Patent
Application |
20190257014 |
Kind Code |
A1 |
Okumura; Katsuya ; et
al. |
August 22, 2019 |
COPPER FIBER NONWOVEN FABRIC
Abstract
Provided is a copper fiber nonwoven fabric having a bonding
portion between copper fibers, and in the relationship between
compressive stress and strain, is provided with a first region
exhibiting plastic deformation and a second region exhibiting
elastic deformation in which compressive stress is higher than the
first region. Alternatively, the copper fiber nonwoven fabric has a
bonding portion between copper fibers, and in the relationship
between compressive stress and strain, has a region exhibiting
elastic deformation, wherein the region exhibiting elastic
deformation has an elastic deformation region before an inflection
portion a, the inflection portion a, and an elastic deformation
region after the inflection portion a.
Inventors: |
Okumura; Katsuya; (Tokyo,
JP) ; Tsuchida; Minoru; (Shizouka-shi, JP) ;
Tsuda; Hajime; (Shizuoka-shi, JP) ; Muramatsu;
Daisuke; (Shizuoka-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tomoegawa Co., Ltd. |
Tokyo |
|
JP |
|
|
Family ID: |
61690439 |
Appl. No.: |
16/334110 |
Filed: |
September 22, 2017 |
PCT Filed: |
September 22, 2017 |
PCT NO: |
PCT/JP2017/034341 |
371 Date: |
March 18, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D04H 1/54 20130101; B01D
39/20 20130101; D10B 2505/04 20130101; D10B 2401/061 20130101; D21H
13/48 20130101; D04H 1/732 20130101; D10B 2101/20 20130101; D04H
1/587 20130101; D04H 1/4234 20130101 |
International
Class: |
D04H 1/4234 20060101
D04H001/4234; D04H 1/587 20060101 D04H001/587; D21H 13/48 20060101
D21H013/48 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 26, 2016 |
JP |
2016-187232 |
Claims
1. A copper fiber nonwoven fabric having a bonding portion between
copper fibers and, in the relationship between compressive stress
and strain, is provided with a first region exhibiting plastic
deformation and, a second region exhibiting elastic deformation in
which compressive stress is higher than the first region.
2. The copper fiber nonwoven fabric according to claim 1, having an
inflection portion a in the second region exhibiting elastic
deformation where strain exhibits inflection in response to
compressive stress.
3. A copper fiber nonwoven fabric having a bonding portion between
copper fibers and, in the relationship between compressive stress
and strain, has a region exhibiting elastic deformation, wherein
the region exhibiting elastic deformation has an elastic
deformation region before an inflection portion a, the inflection
portion a, and an elastic deformation region after the inflection
portion a.
Description
TECHNICAL FIELD
[0001] The present invention relates to a copper fiber nonwoven
fabric obtained by bonding between copper fibers.
[0002] The present application claims priority on the basis of
Japanese Patent Application No. 2016-187232 filed in Japan on Sep.
26, 2016, the contents of which are incorporated herein by
reference.
BACKGROUND ART
[0003] Copper fibers have conventionally been processed into the
form of sheets and are used in, or are being examined for use in,
applications for filters or electromagnetic shielding and the like
by taking advantage of their properties such as electrical
conductivity, bactericidal activity and air permeability.
[0004] An example of such a filter application that has been
proposed consists of a cylindrical metal filter, which enables the
density and thickness of the filter body to be adjusted
corresponding to the size of impurities to be filtered out present
in a high-temperature gas, comprising an internal cylindrical wire
mesh having an overlaying portion welded in the longitudinal
direction, a filter body obtained by winding a felt sheet made of
metal fiber around the internal cylindrical wire mesh at a
prescribed thickness and impregnating and drying a heat-resistant
resin, and an external cylindrical wire mesh having an overlaying
portion welded in the longitudinal direction (see, for example,
Patent Document 1).
[0005] Processing such as needle punching or pressing is presumed
to be used to produce the aforementioned filter body, and metal
fibers capable of plastic deformation are proposed to be used
preferably for the material of the filter body. Copper fibers are
also indicated as being able to be used for these metal fibers.
[0006] In addition, a filter device has been proposed that employs
a sealing structure capable of preventing damage and so forth to a
filtration member by installing an elastic member between a
pressing member and the filtration member, and nickel, chromium,
alloys thereof, stainless steel and titanium alloy are proposed as
examples of metals that can be used for the elastic member (see,
for example, Patent Document 2).
PRIOR ART DOCUMENTS
Patent Documents
[0007] Patent Document 1: Japanese Unexamined Patent Application,
First Publication No. H9-276636
[0008] Patent Document 2: Japanese Unexamined Patent Application,
First Publication No. 2004-305964
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0009] When stress is applied to metal, elastic deformation is
known to typically occur followed by the occurrence of plastic
deformation. "Elastic deformation" refers to deformation in the
case of having applied an external force to an object causing
deformation followed by a return to the original shape when that
external force is removed. On the other hand, "plastic deformation"
refers to deformation in which an external force is applied to an
object causing deformation followed by that deformation remaining
even after the external force is removed.
[0010] However, when metal was used as a material and the like by
focusing on such metal properties of electrical conductivity,
durability and toughness, the metal ended up being governed by the
previously described property, namely the initial occurrence of
elastic deformation followed by the occurrence of plastic
deformation. In addition, the aforementioned elastic deformation
accumulates stain in proportion to, for example, compressive
stress. Thus, a material has been sought that, despite being a
metal, initially exhibits plastic deformation followed by the
occurrence of elastic deformation, which differs from the property
typically demonstrated by metals, and has the property of
undergoing a change in strain in response to, for example,
compressive stress within the region exhibiting that elastic
deformation. In particular, a sheet-like material has been sought
that exhibits the aforementioned properties in the case of
considering the degree of freedom of the shape thereof, such as
being able to be arranged in confined locations.
[0011] However, in Patent Document 1, a filter body is used that is
composed of unbound metal fibers. In addition, although the use of
metal fibers capable of plastic deformation is described in Patent
Document 1, there is no clear description of the intent thereof or
a description regarding elastic deformation.
[0012] Patent Document 2 proposes that sealability is attempted to
be enhanced by utilizing the compressive elastic modulus of a
support body 2B and an elastic member, while there is no
description relating to plastic deformation. In addition, there is
no description relating to a change in strain within a region of
elastic deformation. Moreover, although Patent Document 2 does not
contain any description or suggestion regarding copper fibers, this
is because copper fibers are not preferable for use as metal
capable of satisfying the requirements of strength, corrosion
resistance, heat resistance and toughness in elastic member
applications.
[0013] In contrast, the copper fiber nonwoven fabric of the present
invention has a bonding portion between copper fibers and, in the
relationship between compressive stress and strain, is provided
with a first region exhibiting plastic deformation and a second
region exhibiting elastic deformation in which compressive stress
is higher than in the first region.
[0014] Alternatively, the copper wire nonwoven fabric of the
present invention has a bonding portion between copper fibers and,
in the relationship between compressive stress and strain, has a
region exhibiting elastic deformation, wherein the region
exhibiting elastic deformation has an elastic deformation region
before an inflection portion a, the inflection portion a, and an
elastic deformation region after the inflection portion a.
[0015] As a result thereof, an object of the present invention is
to provide a copper fiber nonwoven fabric that exhibits cushioning
while also having high shape followability.
Means for Solving the Problems
[0016] As a result of conducting extensive studies, the inventors
of the present invention found that, by providing a bonding portion
between copper fibers, a copper fiber nonwoven fabric has, in the
relationship between compressive stress and strain, a first region
exhibiting plastic deformation and a second region exhibiting
elastic deformation in which compressive stress is higher than in
the first region. Alternatively, the inventors of the present
invention found that, by providing a bonding portion between copper
fibers, a copper fiber nonwoven fabric has, in the relationship
between compressive stress and strain, a region exhibiting elastic
deformation, wherein the region exhibiting elastic deformation has
an elastic deformation region before an inflection portion a, the
inflection portion a, and an elastic deformation region after the
inflection portion a, thereby leading to invention of the present
copper fiber nonwoven fabric.
[0017] Namely, the present invention is as described below.
[0018] (1) A copper fiber nonwoven fabric having a bonding portion
between copper fibers and, in the relationship between compressive
stress and strain, is provided with a first region exhibiting
plastic deformation and a second region exhibiting elastic
deformation in which compressive stress is higher than the first
region.
[0019] (2) The copper fiber nonwoven fabric described in (1),
having an inflection portion a in the second region exhibiting
elastic deformation where strain exhibits inflection in response to
compressive stress.
[0020] (3) A copper fiber nonwoven fabric having a bonding portion
between copper fibers and, in the relationship between compressive
stress and strain, has a region exhibiting elastic deformation,
wherein the region exhibiting elastic deformation has an elastic
deformation region before an inflection portion a, the inflection
portion a, and an elastic deformation region after the inflection
portion a.
Effects of the Invention
[0021] The copper fiber nonwoven fabric of the present invention,
in the relationship between compressive stress and strain, has a
first region exhibiting plastic deformation and a second region
exhibiting elastic deformation in which compressive stress is
higher than the first region. Alternatively, the copper fiber
nonwoven fabric of the present invention has a region exhibiting
elastic deformation, wherein the region exhibiting elastic
deformation has an elastic deformation region before an inflection
portion a, the inflection portion a, and an elastic deformation
region after the inflection portion a. As a result, the copper
fiber nonwoven fabric is able to demonstrate favorable cushioning
while having shape followability.
[0022] Namely, in the case the copper fiber nonwoven fabric of the
present invention is subjected to compressive stress, the copper
fiber nonwoven fabric is able to follow the shape of the compressed
object due to the first region exhibiting plastic deformation and
the elastic deformation region before the inflection portion a, and
demonstrate favorable cushioning due to the second region
exhibiting elastic deformation and the elastic deformation region
after the inflection portion a.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a photomicrograph showing an SEM cross-section of
a copper fiber nonwoven fabric.
[0024] FIG. 2 is a photomicrograph showing the state in which
copper fibers are bonded.
[0025] FIG. 3 is a graph obtained during measurement of the
relationship between compressive stress and strain in the copper
fiber nonwoven fabric of the present invention (one
embodiment).
[0026] FIG. 4 is a graph for specifically explaining a region
exhibiting elastic deformation according to the present invention
(second region exhibiting elastic deformation).
[0027] FIG. 5 is a graph obtained during measurement of the
relationship between compressive stress and strain in the copper
fiber nonwoven fabric of another embodiment of the present
invention.
[0028] FIG. 6 is a graph obtained during measurement of the
relationship between compressive stress and strain in the copper
fiber nonwoven fabric of another embodiment of the present
invention.
[0029] FIG. 7 is a graph obtained during measurement of the
relationship between compressive stress and strain in the copper
fiber nonwoven fabric of another embodiment of the present
invention.
[0030] FIG. 8 is a graph obtained during measurement of the
relationship between compressive stress and strain in the copper
fiber nonwoven fabric of another embodiment of the present
invention.
[0031] FIG. 9 is a graph obtained during measurement of the
relationship between compressive stress and strain in the copper
fiber nonwoven fabric of another embodiment of the present
invention.
[0032] FIG. 10 is a graph obtained during measurement of the
relationship between compressive stress and strain of a copper
plate.
[0033] FIG. 11 is a schematic diagram of a pressing device for
confirming cushioning of the copper fiber nonwoven fabric of the
present invention.
[0034] FIG. 12 is a schematic diagram for explaining the details of
a compressed body placed in a pressing device.
[0035] FIG. 13 is a photomicrograph indicating the status of a
pressure-sensitive sheet after a press test of a copper fiber
nonwoven fabric of Example 1.
[0036] FIG. 14 is a photomicrograph indicating the status of a
pressure-sensitive sheet after a press test of a copper fiber
nonwoven fabric of Example 5.
[0037] FIG. 15 is a photomicrograph indicating the status of a
pressure-sensitive sheet after a press test of copper foil of
Comparative Example 1.
BEST MODE FOR CARRYING OUT THE INVENTION
[0038] Although the following provides a detailed explanation of
the copper fiber nonwoven fabric of the present invention,
embodiments of the copper fiber nonwoven fabric of the present
invention are not limited thereto.
[0039] In the present description, a nonwoven fabric refers to a
sheet-like material obtained by randomly entangling fibers, and a
copper fiber nonwoven fabric refers to a nonwoven fabric at least
containing fibers composed of copper. The copper fiber nonwoven
fabric of the present invention may be composed only of copper
fibers or may have a component other than the aforementioned copper
fibers. A bonding portion between the copper fibers refers to a
site where the copper fibers are physically fixed in position. The
copper fibers may be directly fixed each other, may be fixed each
other by a second metal component having a metal component
differing from the metal component of the copper fibers, or a part
of the copper fibers may be fixed each other by a component other
than the metal component. Among these, the copper fibers are
preferably fixed directly from the viewpoints of ease of imparting
favorable shape followability and cushioning to the copper fiber
nonwoven fabric. FIG. 1 is photomicrograph showing an SEM
cross-section of a nonwoven fabric composed only of copper fibers
that was fabricated using copper fibers. In addition, FIG. 2 is a
photomicrograph showing one example of the state of bonding between
copper fibers.
[0040] Although there are no particular limitations on the
aforementioned second metal component, examples thereof include
stainless steel, iron, copper, aluminum, bronze, brass, nickel and
chromium, and may also be a precious metal such as gold, platinum,
silver, palladium, rhodium, iridium, ruthenium or osmium.
[0041] Polyolefins such as polyethylene terephthalate (PET) resin,
polyvinyl alcohol (PVA), polyethylene or polypropylene, polyvinyl
chloride resin, aramid resin, nylon, acrylic resin and organic
materials having bonding properties and support properties of these
fibrous materials can be used in those portions containing bonding
portions as the aforementioned component other than the metal
component.
[0042] Although the average fiber diameter of the copper fibers
according to the present invention can be set arbitrarily within a
range that does not impair the formation of the nonwoven fabric, it
is preferably 1 .mu.m to 70 .mu.m and more preferably 15 .mu.m to
30 .mu.m. If average fiber diameter is less than 1 .mu.m, the
copper fibers tend to easily form so-called clumps when forming
into the nonwoven fabric, while if average fiber diameter exceeds
70 .mu.m, the rigidity of the copper fibers has the risk of acting
to prevent fiber entanglement. In addition, although the
cross-sectional shape of the copper fibers may be any of circular,
elliptical, roughly quadrangular or irregular, at least copper
fibers having a circular cross-section are preferably contained.
Copper fibers having a circular cross-section bend more easily
(bending portions) in response to stress than copper fibers having
a prismatic cross-section, and since a difference in the degree of
bending of the copper fibers is not likely to occur with respect to
those locations subjected to stress, degree of bending also tends
to be uniform. Suitable entanglement of copper fibers having
bending portions tends to facilitate enhancement of shape
followability and cushioning. Here, the circular cross-section is
not required to be perfectly circular, but rather is only required
to be a circular cross-section of a degree that facilitates the
formation of suitable bending portions when subjected to stress
generated in the production of ordinary copper fiber nonwoven
fabric. Furthermore, in the present description, "average fiber
diameter" refers to the average value (such as the average value of
20 fibers) of area diameter derived by calculating (by using known
software, for example) the cross-sectional area of the copper
fibers based on a vertical cross-section at an arbitrary location
of the copper fiber nonwoven fabric photographed with a microscope,
and calculating a diameter of a circle which has the same area as
the aforementioned cross-sectional area.
[0043] The length of the copper fibers according to the present
invention is preferably within the range of 1 mm to 50 mm and more
preferably within the range of 3 mm to 20 mm. If the average fiber
length is within the aforementioned ranges, in the case of, for
example, producing the copper fiber nonwoven fabric by papermaking,
in addition to making it difficult for so-called clumping of the
copper fibers to occur and being able to expect the effect of
facilitating suitable adjustment of dispersion, it also becomes
easy to demonstrate the effect of improving sheet strength
attributable to entanglement of the copper fibers. "Average fiber
length" in the present description refers to the value obtained by
measuring, for example, 20 fibers with a microscope and averaging
the measured values. In addition, "papermaking" refers to the
production of paper and the like by forming the raw material into a
wet, pulpy material and thinly spreading followed by drying.
[0044] Although the thickness of the copper fiber nonwoven fabric
can be adjusted to an arbitrary thickness, it is preferably, for
example, within the range of 50 .mu.m to 1.5 mm and more preferably
150 .mu.m to 350 .mu.m. Furthermore, "sheet thickness" in the
present description refers to average value in the case of, for
example, measuring thickness at several arbitrary measurement
points of the copper fiber nonwoven fabric with a terminal drop
type film thickness gauge using air (such as the ID-C112X Digimatic
Indicator manufactured by Mitutoyo Corp.).
[0045] The space factor of the copper fiber nonwoven fabric of the
present invention is within the range of 5% to 60%, preferably 5%
to 40% and more preferably 10% to 25%. In the case the space factor
is less than 5%, the amount of fiber becomes insufficient, thereby
resulting in the risk in a decrease in shape followability and
cushioning, while if the space factor exceeds 60%, the copper fiber
nonwoven fabric becomes rigid resulting in the risk of a decrease
in shape followability and cushioning. Space factor in the present
description refers to the percentage of the portion where fibers
are present to the volume of the copper fiber nonwoven fabric, and
is calculated according to the equation below from the basis weight
and thickness of the copper fiber nonwoven fabric as well as the
true density of the copper fibers (case of copper fiber nonwoven
fabric composed only of copper fibers).
Space factor (%)=(basis weight of copper fiber nonwoven
fabric)/(thickness of copper fiber nonwoven fabric.times.true
density of copper fibers).times.100
[0046] The following provides an explanation of the case of the
copper fiber nonwoven fabric of the present invention not being
subjected to external force following fabrication.
[0047] Plastic deformation and elastic deformation of the copper
fiber nonwoven fabric of the present invention can be confirmed
from a stress-strain curve by carrying out a compression test using
a cycle consisting of compression and release. Namely, since the
copper fiber nonwoven fabric of the present invention undergoes
plastic deformation due to the operation of the first compression
and release and the copper fiber nonwoven fabric undergoes a
reduction in thickness during the second compression, the starting
point of strain (starting position of the compression probe) also
lowers beyond that at the time of the absence of compression. (For
example, in the graph shown in FIG. 3, since the starting point of
the horizontal axis is the point where plastic deformation of the
uncompressed copper fiber nonwoven fabric starts, strain starting
from the second time is indicated with a positive value.) In the
present description, the low strain side is defined as a plastic
deformation region (first region exhibiting plastic deformation),
and strain beyond the plastic deformation region (high strain side)
is defined as an elastic deformation region (second region
exhibiting elastic deformation or region indicating elastic
deformation) bordering on the strain starting value (compression
probe starting position) at the time of existing compression
(during compression for the second or third time) in the
compression test. Furthermore, the plastic deformation region on
the low strain side is not required to be composed only of plastic
deformation, but rather elastic deformation may also be present in
the plastic deformation region of the low strain side in addition
to plastic deformation.
[0048] FIG. 3 is a graph obtained during measurement of the
relationship between compressive stress and strain in the copper
fiber nonwoven fabric of the present invention described in Example
1 of the present description. In the graph, 1st time to 3rd time
indicates the number of times compression was applied, the plot of
the 1st time indicates measured value during initial compression,
the plot of the 2nd time indicates measured values during the
second compression, and the plot of the 3rd time indicates measured
values during the third compression. According thereto, the copper
fiber nonwoven fabric of the present invention can be determined to
have a first region A exhibiting plastic deformation, and a second
region B exhibiting elastic deformation where compression stress is
higher than in the aforementioned first region. Namely, in contrast
to the first region A exhibiting plastic deformation being absent
in the measured values of the copper plate of FIG. 10, in the
copper fiber nonwoven fabric of the present invention shown in FIG.
3, for example, plastic deformation appears as a first region
followed by the appearance of elastic deformation as a second
region.
[0049] Moreover, the second region B exhibiting elastic deformation
preferably has an inflection portion a where strain exhibits
inflection in response to compressive stress. The "inflection
portion a" refers to the portion where the slope of a tangent
changes rapidly in a stress-strain curve. FIG. 4 is a graph for
specifically explaining the second region exhibiting elastic
deformation according to the present invention (region exhibiting
elastic deformation). The data values are the same as those of FIG.
3. A region B1 exhibiting elastic deformation before the inflection
portion a shown in FIG. 4 (located between region A and inflection
portion a) is understood to be a so-called spring elasticity
region, while a region B2 exhibiting elastic deformation after the
inflection portion a is understood to be a so-called strain
elasticity region where strain is accumulated within the metal.
Namely, the copper fiber nonwoven fabric of the present invention
has region B1 exhibiting elastic deformation before the inflection
portion a and a region B2 exhibiting elastic deformation after the
inflection portion a in the second region B exhibiting elastic
deformation (region exhibiting elastic deformation). As a result,
the effect is demonstrated of facilitating enhancement of shape
followability and cushioning. Furthermore, the inflection portion a
and the region B1 exhibiting elastic deformation before the
inflection portion a are not present in the measured values of the
copper plate of FIG. 10.
[0050] Next, an explanation is provided of the case of the copper
fiber nonwoven fabric already having been subjected to external
force following fabrication.
[0051] In the case of the copper fiber nonwoven fabric of the
present invention having already been subjected to external force
(such as compressive stress) following the fabrication thereof, the
aforementioned first region exhibiting plastic deformation is
basically no longer present (at the stage the first cycle of
compression and release has ended in terms of the example of FIG.
4). However, the copper fiber nonwoven fabric of the present
invention has an elastic deformation region before the inflection
portion a, the inflection portion a, and an elastic deformation
region after the inflection portion a in the region exhibiting
elastic deformation as previously described, even if a region
exhibiting plastic deformation is absent. As a result, shape
followability and cushioning are demonstrated that are superior to
those of typical metals. In addition, a first region exhibiting
plastic deformation ought to be present during fabrication of the
copper fiber nonwoven fabric of the present invention even in the
case of already having been subjected to external force.
[0052] The method used to measure the relationship between
compressive stress and strain in the present description uses a
tension-compression strain measuring tester. First, a square test
piece measuring 30 mm on a side is prepared. The thickness of the
prepared test piece is measured as the thickness before compression
testing using the ID-C112X Digimatic Indicator manufactured by
Mitutoyo Corp. This micrometer is able to raise and lower the probe
using air. In addition, the speed thereof can also be set
arbitrarily. Since the test piece is in a state of being easily
crushed by a small amount of stress, when lowering the measuring
probe, lower as slowly as possible so that only the dead weight of
the probe acts on the test piece. Moreover, the probe is contacted
with the test piece only once. The thickness measured at that time
is taken to be the "pre-test thickness".
[0053] Continuing, the compression test is carried out using the
test piece. A 1 kN load cell is used. A compression probe made of
stainless steel and having a diameter of 100 mm is used for the jig
used in the compression test. The compression rate is set to 1
mm/min and the compression and release operations are consecutively
carried out three times on the test piece. As a result, plastic
deformation and elastic deformation of the copper fiber nonwoven
fabric of the present invention can be confirmed.
[0054] In addition, actual strain in response to stress can be
calculated from the stress-strain curve obtained according to the
compression test, and the amount of plastic deformation can be
calculated in accordance with the equation below.
Amount of plastic deformation=(strain of first rising portion of
curve)-(strain of second rising portion of curve)
[0055] At this time, a rising portion refers to strain at 2.5
N.
[0056] Thickness of the test piece after testing is measured using
the same method as previously described and this is taken to be the
"post-test thickness".
[0057] In addition, the plastic deformation rate of the copper
fiber nonwoven fabric of the present invention is preferably within
a desired range. Plastic deformation rate refers to the degree of
plastic deformation of the copper fiber nonwoven fabric. Plastic
deformation rate (such as the plastic deformation rate when
gradually increasing the load from 0 MPa to 1 MPa) is defined as
indicated below.
Amount of plastic deformation (.mu.m)=T0-T1
Plastic deformation rate (%)=(T0-T1)/T0.times.100
[0058] The aforementioned T0 is the thickness of the copper fiber
nonwoven fabric prior to the application of a load, while the
aforementioned T1 is the thickness of the copper fiber nonwoven
fabric after releasing the load after it has been applied.
[0059] The copper fiber nonwoven fabric of the present invention is
required to have a region where plastic deformation occurs as a
first region or have an elastic deformation region before an
inflection portion a, the inflection portion a, and an elastic
deformation region after the inflection portion a in a region
exhibiting elastic deformation. In the case of the first region
where plastic deformation occurs, the plastic deformation rate is
preferably 1% to 90%, more preferably 4% to 75%, even more
preferably 30% to 60% and most preferably 47% to 60%. As a result
of the plastic deformation rate being 1% or more, shape
followability attributable to plastic deformation can be preferably
secured, thereby making this preferable. On the other hand, as a
result of the plastic deformation rate being 90% or less, plastic
deformation does not become excessive, and as a result of leaving
an adequate margin for elastic deformation, cushioning attributable
to elastic deformation can be secured, thereby making this
preferable.
[0060] Elongation percentage of the copper fiber nonwoven fabric of
the present invention is preferably within the range of 3% to 20%,
more preferably 3% to 10%, and even more preferably 5% to 10%. If
elongation percentage is less than 3%, there is the risk of a
decrease in shape followability in cases, for example, of the
surface of the followed object not being flat. If elongation
percentage exceeds 20%, there is the risk of a decrease in shape
stability of the nonwoven fabric.
[0061] Tensile strength of the copper fiber nonwoven fabric of the
present invention is preferably 2 N/mm to 20 N/10 mm, more
preferably 2 N/10 mm to 10 N/10 mm, and even more preferably 5 N/10
mm to 10 N/10 mm. If tensile strength is less than 2 N/10 mm, there
is the risk of breakage of the copper fiber nonwoven fabric
depending on the manner in which it is used, while if tensile
strength exceeds 20 N/10 mm, there is the risk of a decrease in
shape followability.
[0062] Clark stiffness (JIS P 8143:2009) of the copper fiber
nonwoven fabric of the present invention is preferably 3 to 15,
more preferably 3 to 12 and even more preferably 6 to 12. Although
Clark stiffness may be 3 or less, there is the risk of increased
susceptibility to wrinkling and the like from the viewpoint of
handling of the copper fiber nonwoven fabric. In addition, if Clark
stiffness is 15 or more, there is the risk of the occurrence of
buckling depending on such factors as the shape and diameter of the
followed object. The method used to measure Clark stiffness
consists of a measurement method in which self-weight deflection is
used as an indicator, and a large measured value indicates the
strength of the so-called flexural rigidity of a sample. Thus, if
the measured value of a sheet-like material is within a fixed
range, balance is maintained between ductility and flexural
rigidity and the followability of a followed object having a curved
portion can be said to be superior.
[0063] Although there are no particular limitations on the sheet
resistance value of the copper fiber nonwoven fabric of the present
invention, it is preferably 0.8 m.OMEGA./.quadrature. to 1.5
m.OMEGA./.quadrature.. Sheet resistance value can be determined
according to, for example, the Van der Pauw method.
[0064] (Fabrication of Copper Fiber Nonwoven Fabric)
[0065] The copper fiber nonwoven fabric of the present invention
can be obtained by, for example, a method consisting of compression
molding copper fibers or a web consisting mainly of copper fibers,
or papermaking using a wet papermaking method using copper fibers
or a raw material consisting mainly of copper fibers.
[0066] In the case of obtaining the copper fiber nonwoven fabric of
the present invention by compression molding, copper fibers or a
web consisting mainly of copper fibers obtained by a card method or
air-laid method can be compression-molded. At this time, a binder
may be impregnated between the fibers in order to impart bonds
between the fibers. There are no particular limitations on the
binder, and examples of binders that can be used include organic
binders such as acrylic adhesives, epoxy adhesives or urethane
adhesives, and inorganic binders such as colloidal silica, water
glass or sodium silicate. Instead of impregnating with binder, the
surface of the fibers may be pre-coated with a thermoadhesive resin
followed by applying pressure and heated compression after having
laminated the copper fibers or an aggregate consisting mainly of
copper fibers.
[0067] In addition, the copper fiber nonwoven fabric of the present
invention can also be fabricated by a wet papermaking method in
which copper fibers and the like are dispersed in water and then
thinly spreading out the aqueous dispersion and drying. More
specifically, copper fibers or slurry consisting mainly of copper
fibers can be prepared followed by the suitable addition thereto
of, for example, a filler, dispersant, thickener, antifoaming
agent, paper strength enhancer, sizing agent, flocculant, colorant
or fixing agent. In addition, organic fibers demonstrating
adhesiveness by heating and melting in the manner of polyolefins
such as polyethylene terephthalate (PET) resin, polyvinyl alcohol
(PVA), polyethylene or polypropylene, polyvinyl chloride resin,
aramid resin, nylon or acrylic resin, can be added to the slurry as
fibrous materials other than copper fibers. For example, in the
case of providing a bonding portion between the copper fibers by
sintering, the absence of organic fibers and the like between the
copper fibers more reliably facilitates the providing of a binding
portion (by making it easier to increase the number of bonding
points), and facilitates the obtaining of a first region exhibiting
plastic deformation, a second region exhibiting elastic deformation
in which compressive stress is higher than in the first region, and
an elastic deformation region before an inflection portion a, the
inflection portion a and an elastic deformation region after the
inflection portion a in a region exhibiting elastic deformation.
Consequently, the absence of organic fibers and the like between
the copper fibers is preferable from the viewpoints of making it
easier to impart shape followability and cushioning to the copper
fiber nonwoven fabric of the present invention.
[0068] In the case of producing the copper fibers by a papermaking
method in the absence of organic fibers and the like as previously
described, aggregates such as so-called clumps form easily due to
the difference in true density between water and the copper fibers
and excessive entanglement of the copper fibers. Consequently, it
is preferable to use a suitable thickener and the like. In
addition, in the case of slurry present in a stirring mixer, copper
fibers of high true density tend to easily precipitate to the
bottom of the mixer. Consequently, slurry other than near the
bottom of the mixer where the ratio of copper fibers is
comparatively stable is preferably used for the slurry. Carrying
out this procedure demonstrates the effect of facilitating the
imparting of more accurate shape followability and cushioning with
little in-plane variation.
[0069] Next, wet papermaking is carried out with a papermaking
machine using the aforementioned slurry. A cylinder paper machine,
Fourdrinier paper machine, tanmo machine, inclined paper machine or
combination paper machine combining different types or the same
types of these paper machine can be used as papermaking machines.
Following papermaking, the wet paper can be dehydrated and dried
using an air dryer, cylinder dryer, suction drum dryer or infrared
dryer and the like to obtain a sheet.
[0070] In addition, when dehydrating, it is preferable to make the
flow rate of water generated during dehydration (amount of water
generated during dehydration) to be uniform within the plane or in
the direction of width and so forth of the papermaking wire.
Maintaining a constant flow of dehydration water facilitates the
obtaining of a highly homogeneous copper fiber nonwoven fabric
since disturbances during dehydration are suppressed and the rate
at which the copper fibers precipitate into the papermaking wire is
uniform. In order to maintain a constant flow rate during
dehydration, measures can be adopted such as removing any
structures having the potential to obstruct water flow below the
papermaking wire. This demonstrates the effect of making it easy to
impart the copper fiber nonwoven fabric with more accurate shape
followability and cushioning with little in-plane variation.
[0071] When using a wet papermaking method, it is preferable to
produce the copper fiber nonwoven fabric by going through a fiber
entanglement treatment step in which copper fibers or components
consisting mainly of copper fibers, which form a sheet containing
water on the wire, are mutually entangled. Here, the fiber
entanglement treatment step preferably employs, for example, a
fiber entanglement treatment step in which a high-pressure jet
stream of water is sprayed onto the surface of the wet material
sheet. More specifically, as a result of arranging a plurality of
nozzles in the direction perpendicular to the direction of sheet
flow and spraying a high-pressure jet stream of water from the
plurality of nozzles at the same time, the copper fibers or fibers
consisting mainly of copper fibers are entangled over the entire
sheet. After having gone through the aforementioned step, the wet
material sheet goes through a drying step and is wound up.
[0072] The copper fiber nonwoven fabric of the present invention
fabricated according to the aforementioned process may also be
subjected to, for example, a pressing (pressurizing) step prior to
bonding the copper fibers. By carrying out a pressing step prior to
bonding, bonding portions can be easily provided (the number of
bonding points can be easily increased) more reliably in the
subsequent bonding step, and in addition to a first region
exhibiting plastic deformation and a second region exhibiting
elastic deformation in which compressive stress is higher than the
aforementioned first region, an elastic deformation region before
an inflection portion a, the inflection portion a and an elastic
deformation region after the inflection portion a are easily
obtained in the region exhibiting elastic deformation.
Consequently, it is preferably to carry out the pressing step prior
to bonding from the viewpoints of making it easy to impart shape
followability and cushioning to the copper fiber nonwoven fabric of
the present invention. In addition, although pressing may be
carried out in the presence of heating or in the absence of
heating, in the case the copper fiber nonwoven fabric of the
present invention contains organic fibers and the like that
demonstrating bonding properties as a result of heating and
melting, it is effective to heat the fibers to a temperature equal
to or higher than the melt starting temperature thereof, while in
the case the copper fiber nonwoven fabric is composed by containing
copper fibers alone or a second metal component, the fibers are
only required to be pressed. Moreover, although the pressure
applied during pressing may be suitably set in consideration of the
thickness of the copper fiber nonwoven fabric, for example, in case
of the copper fiber nonwoven fabric having a thickness of about 170
.mu.m, by carrying out pressing at a linear pressure of less than
300 kg/cm and preferably less than 250 kg/cm, shape followability
and cushioning are easily imparted to the copper fiber nonwoven
fabric of the present invention, thereby making this preferable. In
addition, this pressing step makes it possible to adjust the space
factor of the copper fiber nonwoven fabric.
[0073] Examples of methods that can be used to bond copper fibers
of a copper fiber nonwoven fabric prepared in this manner include a
method consisting of sintering the copper fiber nonwoven fabric, a
method consisting of bonding by chemical etching, a laser fusion
method, a bonding method using induction heating (IH), a chemical
bonding method and a thermal bonding method. Among the
aforementioned methods, a method consisting of sintering the copper
fiber nonwoven fabric is preferable from the viewpoints of easily
obtaining a first region exhibiting plastic deformation and a
second region exhibiting elastic deformation in which compressive
stress is higher than the aforementioned first region, as well as
an elastic deformation region before an inflection portion a, the
inflection portion a and an elastic deformation region after the
inflection portion a in the region exhibiting elastic deformation,
while also facilitating the imparting of shape followability and
cushioning to the copper fiber nonwoven fabric of the present
invention. FIG. 2 is a photomicrograph observed by SEM of a
cross-section of a copper fiber nonwoven fabric in which the copper
fibers are bonded by sintering.
[0074] A sintering step in which the copper fiber nonwoven fabric
is sintered at a temperature equal to or lower than the melting
point of the copper fibers in a vacuum or non-oxidizing atmosphere
is preferably included for sintering the copper fiber nonwoven
fabric. After having gone through the sintering step, the copper
fiber nonwoven fabric has lost organic matter, and as a result of
bonding at the contact points between copper fibers of a sheet
composed only of copper fibers in this manner, more favorable shape
followability and cushioning can be imparted to the metal fiber
sheet.
[0075] Moreover, the homogeneity of the sintered copper fiber
nonwoven fabric can be further enhanced by carrying out a pressing
(pressurizing) step after sintering. Compressing a copper fiber
nonwoven fabric, in which the fibers have been randomly entangled,
in the direction of thickness not only causes a shift in the fibers
in the direction of thickness, but also in the planar direction. As
a result, the effect of facilitating the arrangement of copper
fibers even at those locations where there were voids during
sintering can be expected to be demonstrated, and such a state can
be maintained by a plastic deformation property of copper fibers.
As a result, the effect is demonstrated of facilitating the
imparting of more accurate shape followability and cushioning to
the copper fiber nonwoven fabric with little in-plane variation.
Pressure during pressing (pressurizing) is suitably set in
consideration of the thickness of the copper fiber nonwoven
fabric.
[0076] (Applications of Copper Fiber Nonwoven Fabric)
[0077] Next, an explanation is provided of applications of the
copper fiber nonwoven fabric of the present invention. Although
there are no particular limitations on applications of the copper
fiber nonwoven fabric of the present invention, it can be used in a
wide range of applications such as whole sound transmission
materials for providing microphones with wind protection, members
providing countermeasures against electromagnetic noise used in
electronic circuit boards for the purpose of suppressing
electromagnetic waves, copper fiber nonwoven fabric heat transfer
materials used as measures against heat generation by
semiconductors when soldering to connect semiconductor chips, as
well as in applications for providing countermeasures against heat
dissipation, heat generation or electromagnetic waves such as in
construction materials, vehicles, aircraft and marine members.
EXAMPLES
Example 1
[0078] Copper fibers having a fiber diameter of 18.5 .mu.m, fiber
length of 10 mm and a roughly circular cross-sectional shape were
dispersed in water followed by the suitable addition of a thickener
to obtain papermaking slurry. This papermaking slurry was loaded
onto a papermaking mesh based on a basis weight of 300 g/m.sup.2
followed by dehydrating and drying to obtain a copper fiber
nonwoven fabric. Subsequently, after pressing the same nonwoven
fabric at a linear pressure of 240 kg/cm at normal temperature, the
nonwoven fabric was heated for 40 minutes at 1020.degree. C. in an
atmosphere consisting of 75% hydrogen gas and 25% nitrogen gas to
obtain the copper fiber nonwoven fabric of Example 1. The thickness
of the resulting copper fiber nonwoven fabric was 166.9 .mu.m and
the space factor was 19.4%.
[0079] Graphs obtained during measurement of the relationship
between compressive stress and strain in the copper fiber nonwoven
fabric of Example 1 are shown in FIGS. 3 and 4.
Example 2
[0080] The copper fiber nonwoven fabric of Example 2 was obtained
in the same manner as Example 1 with the exception of adjusting the
thickness to 213.8 .mu.m and the space factor to 15.8%.
[0081] A graph obtained during measurement of the relationship
between compressive stress and strain in the copper fiber nonwoven
fabric of Example 2 is shown in FIG. 5.
Example 3
[0082] The copper fiber nonwoven fabric of Example 3 was obtained
in the same manner as Example 1 with the exception of adjusting the
thickness to 332.8 .mu.m and the space factor to 10.3%.
[0083] A graph obtained during measurement of the relationship
between compressive stress and strain in the copper fiber nonwoven
fabric of Example 3 is shown in FIG. 6.
Example 4
[0084] The copper fiber nonwoven fabric of Example 4 was obtained
in the same manner as Example 1 with the exception of using copper
fibers having a fiber diameter of 30 .mu.m and fiber length of 10
mm and adjusting the thickness to 149 .mu.m and the space factor to
24%.
[0085] A graph obtained during measurement of the relationship
between compressive stress and strain in the copper fiber nonwoven
fabric of Example 4 is shown in FIG. 7.
Example 5
[0086] The copper fiber nonwoven fabric of Example 5 was obtained
in the same manner as Example 1 with the exception of using copper
fibers having a fiber diameter of 40 .mu.m and fiber length of 10
mm and adjusting the thickness to 177 .mu.m and the space factor to
18.8%.
[0087] A graph obtained during measurement of the relationship
between compressive stress and strain in the copper fiber nonwoven
fabric of Example 5 is shown in FIG. 8.
Example 6
[0088] The copper fiber nonwoven fabric of Example 6 was obtained
in the same manner as Example 1 with the exception of using copper
fibers having a fiber diameter of 50 .mu.m and fiber length of 10
mm and adjusting the thickness to 179 .mu.m and the space factor to
20.4%.
[0089] A graph obtained during measurement of the relationship
between compressive stress and strain in the copper fiber nonwoven
fabric of Example 6 is shown in FIG. 9.
Comparative Example 1
[0090] Surface-roughened copper foil having a thickness of 40 .mu.m
was prepared. The space factor of this copper foil was 80%.
[0091] A graph obtained during measurement of the relationship
between compressive stress and strain in the copper foil of
Comparative Example 1 is shown in FIG. 10.
[0092] (Measurement of Sheet Thickness)
[0093] The thicknesses of the copper fiber nonwoven fabrics
obtained in the examples and the copper foil obtained in the
comparative example were measured with a probe having a diameter of
15 mm using the ID-C112X Digimatic Indicator manufactured by
Mitutoyo Corp. The thicknesses of the resulting sheets were
measured at 9 points and the average value thereof was taken to be
the thickness of the sheet.
[0094] (Measurement of Sheet Dimensions)
[0095] The dimensions of the short side and long side of the copper
fiber nonwoven fabrics obtained in the examples and copper foil
obtained in the comparative example were measured using a JIS first
class metal ruler.
[0096] (Space Factor)
[0097] Space factor of the copper fiber nonwoven fabrics obtained
in the examples was calculated in the manner indicated below.
Space factor (%)=(basis weight of copper fiber nonwoven
fabric/thickness of copper fiber nonwoven fabric.times.true density
of copper fibers).times.100
[0098] Space factor of the copper foil obtained in the comparative
example was calculated in the manner indicated below.
Space factor (%)=bulk density of the sheet/true specific gravity of
the material.times.100
[0099] (Confirmation of Plastic/Elastic Deformation)
[0100] The relationship between compressive stress and strain of
the sheet-like materials (such as copper fiber nonwoven fabrics)
prepared in the examples and comparative examples was measured
according to the method indicated below.
[0101] The aforementioned sheet-like materials were cut into
squares measuring 30 mm on a side followed by placing in a
tension-compression strain measuring tester (trade name: RTC-1210A,
A & D Co., Ltd.). The thickness of the sheet-like material
prior to compression testing is the value obtained by measuring
using the aforementioned method for measuring sheet thickness.
Since the sheet-like material has the potential for being crushed
even by a small amount of stress, when lowering the measuring
probe, lower as slowly as possible so that only the dead weight of
the probe acts on the sheet-like material. Moreover, the probe is
contacted with the sheet-like material only once. The thickness
measured in this manner is taken to be the "pre-test
thickness".
[0102] Continuing, a compression test is carried out using the
sheet-like materials. A 1 kN load cell is used. A compression probe
made of stainless steel and having a diameter of 100 mm is used for
the jig used in the compression test. The compression rate is set
to 1 mm/min and the compression and release operations are
consecutively carried out three times on the sheet-like material.
As a result, plastic deformation and elastic deformation of the
sheet-like material can be confirmed. Actual strain in response to
stress can be calculated from a "stress-strain curve chart"
obtained from testing, and the amount of plastic deformation and
plastic deformation rate can be calculated in accordance with the
equation below.
Amount of plastic deformation (.mu.m)=T0-T1
Plastic deformation rate (%)=(T0-T1)/T0.times.100
[0103] The aforementioned T0 refers to the thickness of the copper
fiber nonwoven fabric prior to applying the load, while the
aforementioned T1 refers to the thickness of the copper fiber
nonwoven fabric after releasing the load after it has been
applied.
[0104] Thickness of the test piece after testing is measured using
the same method as previously described and this is taken to be the
"post-test thickness". Thickness after testing was measured 3 hours
following completion of testing.
[0105] (Measurement of Elongation Percentage and Tensile
Strength)
[0106] Area of the test piece was adjusted to 15 mm.times.180 mm in
compliance with JIS P8113 followed by measuring the elongation
percentage and tensile strength of the copper fiber nonwoven
fabrics of the examples and copper foil of the comparative example
at a pulling speed of 30 mm/min.
[0107] (Pressing Test)
[0108] Shape followability and cushioning of the sheet-like
materials (such as copper fiber nonwoven fabrics) prepared in the
examples and comparative example were confirmed according to the
method indicated below.
[0109] The aforementioned sheet-like materials were cut to 100
mm.times.150 mm followed by superimposing an SUS plate 9
(thickness: 1 mm), elastic body 11 (thickness: 1 mm), mirrored SUS
plate 10 (thickness: 1 mm), resin sheet 12 (thickness: 0.97 mm),
sheet-like material 13 (such as a copper fiber nonwoven fabric),
pressure-sensitivity sheet 14 (thickness: 0.18 mm), mirrored SUS
plate 10 (thickness: 1 mm), elastic body 11 (thickness: 1 mm) and
SUS plate 9 (thickness: 1 mm) in that order starting from the top
to form a compressed body 7 as shown in FIG. 12. Next, the
compressed body is placed between a stationary plate 6 and a
movable plate 8 of the pressing device 3 shown in FIG. 11 provided
with a power supply 4 and a heater 5, and after hot-pressing under
conditions of 120.degree. C. and 0.5 MPa for 2 minutes, cold
pressing was carried out under conditions of 0.5 MPa for 3 minutes.
Subsequently, the pressure was released and the degree of
discoloration of the pressure-sensitive sheet 14 was observed and
evaluated.
[0110] A pre-scale ultra-low pressure sheet (two-sheet type,
Fujifilm Corp.) was used for the pressure-sensitive sheet 14.
[0111] Evaluation criteria were as indicated below.
[0112] .circleincircle.: Hardly any white areas where pressure is
not sensed
[0113] .largecircle.: Slight appearance of white areas indicative
of low sensitivity but no clear difference in in-plane pressure
sensitivity
[0114] X: Prominent presence of white areas indicative of low
sensitivity and prominent difference in in-plane pressure
sensitivity
[0115] FIG. 13 is a photomicrograph of the pressure-sensitive sheet
of Example 1 after the press test, FIG. 14 depicts that of Example
5 and FIG. 15 depicts that of Comparative Example 1.
[0116] (Clark Stiffness Test)
[0117] Shape followability of the sheet-like materials (such as
copper fiber nonwoven fabrics) of the examples and comparative
example was confirmed with the Clark Stiffness Tester Method of JIS
P 8143:2009.
[0118] The presence or absence of plastic deformation and elastic
deformation, results of the press test and Clark stiffness and the
like of the copper fiber nonwoven fabrics of the examples and
copper foil of the comparative example are shown in Table 1.
[0119] Physical property values and the like of the copper fiber
nonwoven fabrics of the examples and copper foil of the comparative
example are shown in Table 2.
TABLE-US-00001 TABLE 1 Presence or absence of plastic deformation/
Region exhibiting elastic elastic deformation deformation First
Second Presence region region Presence or absence Presence
exhibiting exhibiting or of or Press plastic elastic absence
inflection absence test Clark deformation deformation of B1 portion
of B2 results stiffness Ex. 1 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .circleincircle. 6.5 Ex.
2 .largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .circleincircle. 7.3 Ex. 3 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.circleincircle. 11.1 Ex. 4 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .circleincircle. 6.3 Ex.
5 .largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. 5.9 Ex. 6 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. 3.4 Comp. X
.largecircle. X X .largecircle. X 17.7 Ex. 1
TABLE-US-00002 TABLE 2 Amount Avg. Avg. of fiber fiber Space
plastic Plastic Elongation Tensile diameter length Thickness factor
deformation deformation percentage strength (.mu.m) (mm) (.mu.m)
(%) (.mu.m) rate (%) (%) (N/10 mm) Ex. 1 18.5 10 166.9 19.4 87 47.9
8.2 7.7 Ex. 2 18.5 10 213.8 15.8 125 53.9 9.5 7.7 Ex. 3 18.5 10
332.8 10.3 163 59.7 9.2 8 Ex. 4 30 10 149 24 86 57.7 5.4 6.4 Ex. 5
40 10 177 18.8 80 46.2 4 3.5 Ex. 6 50 10 179 20.4 50 33.5 3.6 2.9
Comp. -- -- 40 80 0 0 1.5 103.7 Ex. 1
[0120] As has been described above, the copper fiber nonwoven
fabric of the present invention was determined to have the effect
of equalizing differences in in-plane pressure based on the results
of press testing as shown in the examples, and have greater
ductility than copper foil according to the Clark stiffness tester
method. Namely, the copper fiber nonwoven fabric of the present
invention, in the relationship between compressive stress and
strain, has a first region exhibiting plastic deformation and a
second region exhibiting elastic deformation in which compressive
stress is higher than in the first region, or has a region
exhibiting elastic deformation and the region exhibiting elastic
deformation has an elastic deformation region before an inflection
portion a, the inflection portion a, and an elastic deformation
region after the inflection portion a. As a result, it is able to
demonstrate high shape followability and cushioning.
INDUSTRIAL APPLICABILITY
[0121] A copper fiber nonwoven fabric can be provided that has
cushioning while also have high shape followability.
BRIEF DESCRIPTION OF THE REFERENCE SYMBOLS
[0122] 1 Copper fiber
[0123] 2 Bonding portion
[0124] A First region exhibiting plastic deformation
[0125] B Second region exhibiting elastic deformation (region
exhibiting elastic deformation)
[0126] B1 Elastic deformation region before inflection portion
a
[0127] B2 Elastic deformation region after inflection portion a
[0128] a Inflection portion
[0129] 3 Pressing device
[0130] 4 Power supply
[0131] 5 Heater
[0132] 6 Stationary plate
[0133] 7 Compressed body
[0134] 8 Movable plate
[0135] 9 SUS plate
[0136] 10 Mirrored SUS plate
[0137] 11 Elastic body
[0138] 12 Resin sheet
[0139] 13 Sheet-like material
[0140] 14 Pressure-sensitive sheet
* * * * *