CA 03030941 2019-01-15
1
METAL ELECTRODEPOSTTION CATHODE PLATE AND PRODUCTION METHOD
THEREFOR
TECHNICAL FIELD
The present invention relates to a metal
electrodeposition cathode plate and a production method
therefor.
BACKGROUND ART
Conventionally, electric nickel serving as an anode raw
material for nickel plating has been used by being placed in a
titanium basket to be an anode holding tool and hung in a
nickel plating tank. At this time, as the electric nickel of
an anode raw material, those obtained by cutting plate-shaped
electric nickel electrodeposited on a cathode plate into small
pieces have been used.
However, the corner of the small pieces of electric
nickel is sharp, and it has been thus difficult to handle the
electric nickel when charging the electric nickel into a
titanium basket. In addition, the small pieces of electric
nickel cause so-called scaffold bridging as the corner thereof
is caught by the mesh of the titanium basket after the
electric nickel was charged in the titanium basket, the
filling state of electric nickel in the titanium basket
changes, and this causes plating unevenness in some cases.
Hence, it has been proposed to use blobby (button-shaped)
electric nickel with rounded corner. The blobby electric
CA 03030941 2019-01-15
2
nickel can be produced, for example, by precipitating nickel
on a conductive portion by using a cathode plate on which a
plurality of circular conductive portions is disposed at
regular intervals by electrolysis and then peeling off the
electrodeposited nickel from the conductive portion. According
to such a method, it is possible to efficiently produce a
plurality of pieces of blobby electric nickel from one cathode
plate.
Fig. 5 is a view illustrating an example of a
conventional cathode plate to be used in production of blobby
electric nickel. A cathode plate 11 is masked with a non-
conductive film 13 on a flat plate-shaped metal plate 12
except the place to be a conductive portion 12a, and the
conductive portion 12a is a concave portion and the non-
conductive film 13 is a convex portion on this cathode plate
11. Nickel having a proper size is electrodeposited on the
conductive portion 12a and blobby electric nickel is thus
produced by using such a cathode plate 11.
As a method for forming the non-conductive film 13 on the
metal plate 12 as the cathode plate 11, for example, there is
a method for forming a non-conductive film 13 having a desired
pattern by coating a thermosetting non-conductive resin such
as an epoxy resin on the flat plate-shaped metal plate 12 by a
screen printing method and heating the thermosetting non-
conductive resin as illustrated in Fig. 6A (see Patent
Documents 1 and 2). Incidentally, Fig. 6B illustrates a state
in which nickel (electric nickel) 14 is electrodeposited and
CA 03030941 2019-01-15
3
precipitated on the conductive portion 12a by using the
cathode plate 11 on which the non-conductive film 13 is formed.
In the cathode plate 11, the nickel 14 begins to be
electrodeposited and precipitated from the conductive portion
12a, grows not only in the thickness (longitudinal) direction
but also in the planar (lateral) direction, and is in the
state of being piled on the upper portion of the non-
conductive film 13 as well.
In addition, for example, there has also been proposed a
method for forming a non-conductive film 23 having a desired
pattern by coating a photosensitive non-conductive resin on a
metal plate 22 and removing the non-conductive resin at the
place corresponding to a conductive portion 22a by exposure
and development as illustrated in Fig. 7A. Incidentally, Fig.
7B illustrates a state in which nickel (electric nickel) 24 is
electrodeposited and precipitated on the conductive portion
22a by using the cathode plate 21 on which the non-conductive
film 23 is formed. In the cathode plate 21 as well, the nickel
24 begins to be electrodeposited and precipitated from the
conductive portion 22a and grows not only in the thickness
direction but also in the planar direction.
Furthermore, there has also been proposed a method for
producing a cathode plate constituting a non-conductive
portion by solidifying the periphery of a metal structure
incorporated so that a plurality of studs to be a conductive
portion is disposed at regular intervals with an insulating
resin by an injection molding method (see Patent Document 3).
4
Patent Document 1: Japanese Examined Patent Application
Publication No. S51-036693
Patent Document 2: Japanese Unexamined Patent Application,
Publication No. S52-152832
Patent Document 3: Japanese Examined Patent Application
Publication No. S56-029960
SUMMARY
Certain exemplary embodiments provide a metal
electrodeposition cathode plate comprising: a metal plate
having a plurality of disc-shaped protrusions disposed on at
least one surface of the metal plate; and a non-conductive
film formed on a surface of the metal plate except the
protrusions, wherein a height X of each protrusion is 40 pm or
more and 500 pm or less, a minimum film thickness Y of the
non-conductive film at a position between centers of the
adjacent protrusions is 50 pm or more and 510 pm or less, and
a difference (Y - X) between the minimum film thickness Y and
the height X of the protrusion is 10 pm or more and 100 pm or
less.
Other exemplary embodiments provide a method for
producing a metal electrodeposition cathode plate, comprising:
a first step of forming a plurality of disc-shaped
protrusions on at least one surface of a metal plate; and a
second step of forming a non-conductive film on a surface of
the metal plate except the protrusions, wherein a height X of
each protrusion is set to be 40 pm or more and 500 pm or less
Date Recue/Date Received 2020-04-29
4a
in the first step, a minimum film thickness Y of the non-
conductive film at a position between centers of the adjacent
protrusions is set to be 50 pm or more and 510 pm or less in
the second step, and a difference (Y - X) between the minimum
film thickness Y and the height X of the protrusion is set to
be 10 pm or more and 100 pm or less in the second step.
DESCRIPTION OF SELECTED EMBODIMENTS
Meanwhile, in a case in which blobby electric nickel is
produced using a cathode plate as described above, it is
required that the non-conductive film (non-conductive portion)
to be formed on the cathode plate has a long service life and
can be easily maintained even in the case of being lost
(deteriorated).
The film thickness of the non-conductive film 13
gradually decreases toward the conductive portion 12a and is
thus significantly thin at the boundary with the conductive
portion 12a in a case in which the non-conductive film 13 is
formed by coating a non-conductive resin on the metal plate 12
by screen printing as illustrated in Fig. 6A. Such a change in
the film thickness of the non-conductive film 13 depends on
the amount of the non-conductive resin coated, the viscosity
and temperature characteristics of viscosity of the non-
conductive resin, the curing temperature of the non-conductive
resin, the surface roughness and surface free energy of the
metal surface, and the like. Hence, the film thickness of the
Date Recue/Date Received 2020-04-29
CA 03030941 2019-01-15
non-conductive film 13 is significantly thin at the boundary
with the conductive portion 12a.
As described above, the nickel 14 begins to be
electrodeposited and precipitated from the conductive portion
12a, grows not only in the longitudinal direction but also in
the lateral direction, and thus is in the state of gradually
being piled on the non-conductive film 13 as well when blobby
electric nickel is produced by using the cathode plate 11 as
illustrated in Fig. 5 and Fig. 6. Hence, the part of the thin
non-conductive film 13 to be formed in the vicinity of the
boundary with the conductive portion 12a is likely to be lost
by the stress at the time of electrodeposition of the nickel
14 and the impact at the time of peeling off of the electric
nickel as well as the adhesive property of the part with the
metal plate 12 is likely to diminish by penetration of the
electrolytic solution. In addition, the non-conductive film 13
in the vicinity of the non-conductive film 13 lost rises from
the surface of the metal plate 12 when loss of the non-
conductive film 13 once occurs, thus the electrolytic solution
is more likely to enter the gap, and as a result, the
electrolytic solution gets into the gap of the non-conductive
film 13 risen from the surface of the metal plate 12 and the
nickel 14 is electrodeposited when it is attempted to
continuously electrodeposit nickel. Thereafter, the non-
conductive film 13 in which the nickel 14 is bitten is further
lost when it is attempted to peel off the nickel 14
electrodeposited by being gotten into the gap.
CA 03030941 2019-01-15
6
In this manner, in the conventional cathode plate 11,
when loss of the non-conductive film 13 occurs and the lost
part expands in a chain reaction, the nickel 14 grown from the
adjacent conductive portions 12a is likely to be connected to
each other, electric nickel having a desired shape cannot be
obtained, and a defective product is produced. Accordingly, it
is required to peel off the entire non-conductive films 13
before loss of the non-conductive film 13 occurs, to form the
non-conductive film 3 again, and thus to maintain the cathode
plate 11. However, in reality, it is required to perform
maintenance of the cathode plate 11 at the stage at which the
electrodeposition treatment of nickel is conducted about from
several times to at most less than 10 times, and not only the
productivity decreases but the maintenance cost also increases.
On the other hand, it is possible to form the non-
conductive film 23 having a uniform film thickness in the
cathode plate 21 in which the non-conductive film 23 is formed
using a photosensitive non-conductive resin by exposure and
development as illustrated in Fig. 7A. However, the nickel 24
is caught by the step of the non-conductive film 23
constituting the convex portion when the nickel 24 is peeled
off after the electrodeposition, a large impact is likely to
be applied to the non-conductive film 23, and thus loss of the
non-conductive film 23 occurs in this case as well.
Incidentally, in the method for forming a non-conductive
portion by injection molding as in Patent Document 3, the
production cost of the cathode plate itself increases and it
CA 03030941 2019-01-15
7
is difficult to maintain the cathode plate in a case in which
the non-conductive portion is deteriorated although the
service life of the non-conductive portion to be formed
increases.
In view of such conventional circumstances, an object of
the present invention is to provide a metal electrodeposition
cathode plate in which a non-conductive film on a metal plate
is hardly lost and which can be repeatedly used and a
production method therefor.
Means for Solving the Problems
The inventors of the present invention have carried out
intensive investigations in order to solve the problems
described above. As a result, it has been found out that the
non-conductive film is hardly lost as protrusions are provided
on a metal plate to form a conductive portion and a non-
conductive film is provided on the metal surface except the
protrusions, whereby the present invention has been completed.
(1) A first aspect of the present invention is a metal
electrodeposition cathode plate, which includes a metal plate
having a plurality of disc-shaped protrusions disposed on at
least one surface of the metal plate and a non-conductive film
formed on a surface of the metal plate except the protrusions,
in which a minimum film thickness of the non-conductive film
at a position between centers of the adjacent protrusions is
the same as or greater than a height of the protrusion.
(2) A second aspect of the present invention is the metal
electrodeposition cathode plate according to the first aspect,
CA 03030941 2019-01-15
8
in which the height of the protrusion is 50 pm or more and
1000 pm or less.
(3) A third aspect of the present invention is the metal
electrodeposition cathode plate according to the first or
second aspect, in which a difference between the minimum film
thickness of the non-conductive film at the position between
centers of the adjacent protrusions and the height of the
protrusion is 200 pm or less.
(4) A fourth aspect of the present invention is the metal
electrodeposition cathode plate according to any one of the
first to third aspects, in which the metal plate is formed of
titanium or stainless steel.
(5) A fifth aspect of the present invention is the metal
electrodeposition cathode plate according to any one of the
first to fourth aspects, in which the metal electrodeposition
cathode plate is used in production of electric nickel for
plating.
(6) A sixth aspect of the present invention is a method
for producing a metal electrodeposition cathode plate, which
includes a first step of forming a plurality of disc-shaped
protrusions on at least one surface of a metal plate and a
second step of forming a non-conductive film on a surface of
the metal plate except the protrusions, in which a minimum
film thickness of the non-conductive film at a position
between centers of the adjacent protrusions is set to be the
same as or greater than a height of the protrusion in the
second step.
CA 03030941 2019-01-15
9
Effects of the Invention
According to the present invention, it is possible to
provide a metal electrodeposition cathode plate in which a
non-conductive film is hardly lost and which can be repeatedly
used and a production method therefor.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a plan view illustrating a configuration of a
cathode plate.
Fig. 2 is an enlarged cross-sectional view of a main part
illustrating a configuration of a cathode plate, Fig. 2A is an
enlarged cross-sectional view of a main part for describing
the state of a cathode plate before nickel electrodeposition,
and Fig. 2B is an enlarged cross-sectional view of a main part
for describing the state of a cathode plate after nickel
electrodeposition.
Fig. 3 is an enlarged cross-sectional view of a main part
illustrating a configuration of a cathode plate in a case in
which the film thickness of the non-conductive film is thin,
Fig. 3A is an enlarged cross-sectional view of a main part for
describing the state of a cathode plate before nickel
electrodeposition, and Fig. 3B is an enlarged cross-sectional
view of a main part for describing the state of a cathode
plate after nickel electrodeposition.
Fig. 4 is an enlarged cross-sectional view of a main part for
describing a method for producing a cathode plate, Fig. 4A is
an enlarged cross-sectional view of a main part for describing
CA 03030941 2019-01-15
a first step, and Fig. 4B is an enlarged cross-sectional view
of a main part for describing a second step.
Fig. 5 is a plan view illustrating a configuration of a
conventional cathode plate.
Fig. 6 is an enlarged cross-sectional view of a main part
illustrating a configuration of a conventional cathode plate,
Fig. 6A is an enlarged cross-sectional view of a main part for
describing the state of a cathode plate before nickel
electrodeposition, and Fig. 6B is an enlarged cross-sectional
view of a main part for describing the state of a cathode
plate after nickel electrodeposition.
Fig. 7 is an enlarged cross-sectional view of a main part
illustrating a configuration of a conventional cathode plate,
Fig. 7A is an enlarged cross-sectional view of a main part for
describing the state of a cathode plate before nickel
electrodeposition, and Fig. 7B is an enlarged cross-sectional
view of a main part for describing the state of a cathode
plate after nickel electrodeposition.
PREFERRED MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment (hereinafter referred to as
the "present embodiment") in which the metal electrodeposition
cathode plate of the present invention is applied to a metal
electrodeposition cathode plate to be used in the production
of electric nickel will be described in detail. It should be
noted that the present invention is not limited to the
following embodiments and can be appropriately changed without
CA 03030941 2019-01-15
11
changing the gist of the present invention.
<1. Metal electrodeposition cathode plate>
(1) Configuration of cathode plate
A cathode plate 1 according to the present embodiment
includes a metal plate 2 on which a plurality of disc-shaped
protrusions 2a is disposed and a non-conductive film 3 formed
on the surface of the metal plate 2 except the protrusions 2a
as illustrated in Fig. 1. The cathode plate 1 is used, for
example, by being hung in an electrolytic cell containing an
electrolytic solution containing nickel and an anode by a
hanging member 5 and nickel having a desired shape is
electrodeposited and precipitated on the surface of the
cathode plate as to be described later.
[Metal plate]
The metal plate 2 is a plate of a metal having a flat
plate shape and has a plurality of disc-shaped protrusions 2a
as illustrated in Fig. 1 and Fig. 2A. Here, the surface of the
metal plate 2 except the protrusion 2a is referred to as a
"flat area 2b" with respect to the protrusion 2a. In addition,
the "height X of the protrusion" is the protruding height from
the surface of the flat area 2b of the metal plate 2.
Incidentally, an example in which the protrusion 2a is
provided on one surface of the metal plate 2 is illustrated in
Fig. 2, but the protrusion 2a may be provided on both surfaces
of the metal plate 2.
The size of the metal plate 2 is not particularly limited,
and it may be set according to the desired size and number of
CA 03030941 2019-01-15
12
electric nickel to be produced as appropriate. For example,
the size can be set to a rectangular size of which one side is
100 mm or more and 2000 mm or less. In addition, the thickness
of the metal plate 2 is preferably, for example, about 1.5 mm
or more and about 5 mm or less in a case in which the
protrusion 2a is provided on one surface, and it is preferably,
for example, about 3 mm or more and about 10 mm or less in a
case in which the protrusion 2a is provided on both surfaces.
There is a tendency that warpage is likely to occur by the
protrusion 2a and the flat area 2b when the thickness of the
metal plate 2 is too thin. On the other hand, the weight of
the metal plate 2 increases and it is difficult to handle the
metal plate 2 when the thickness of the metal plate 2 is too
thick.
The material for the metal plate 2 is not particularly
limited as long as it is a metal which is less susceptible to
corrosion by the electrolytic solution to be used and forms
only loose bonding with an electrodeposit such as nickel, but
preferred examples thereof may include titanium and stainless
steel.
On the metal plate 2, a concave step is formed by the
adjacent protrusions 2a in order to form the non-conductive
film 3 having a predetermined thickness as well as the surface
of a plurality of disc-shaped protrusions 2a is exposed from
the non-conductive film 3 to be described later and functions
as a conductive portion. Hereinafter, the surface of the
protrusions 2a to be exposed from the non-conductive film 3 is
CA 03030941 2019-01-15
13
referred to as a "conductive portion 2c" in some cases. Nickel
4 is electrodeposited and precipitated on the conductive
portion 2c by an electrolytic treatment.
The size of the disc-shaped protrusion 2a may be set
according to the desired size of electric nickel as
appropriate, but the diameter thereof can be set to, for
example, 5 mm or more and 30 mm or less. In addition, the
height X of the protrusion 2a is preferably 50 pm or more and
1000 pm or less and more preferably 100 pm or more and 500 pm
or less. When the height X of the protrusion 2a is too low,
the film thickness of the non-conductive film 3 to be formed
on the flat area 2b of the metal plate 2 is insufficient and
the non-conductive film is likely to be lost by the stress at
the time of electrodeposition of the nickel 4 and the impact
at the time of peeling off of the electric nickel. On the
other hand, when the height X of the protrusion 2a is too high,
for example, the number of coating increases and the
productivity decreases when forming a non-conductive film by
screen printing. In addition, when the height X is too high,
distortion of the metal plate 2 is likely to occur at the time
of processing of the protrusion 2a, the metal plate 2 is
likely to warp, and it is thus difficult to form the non-
conductive film 3. Incidentally, it is also possible to
increase the thickness of the metal plate 2 in order to
diminish the influence of distortion of the metal plate 2, but
the weight of the metal plate 2 increases and it is difficult
to handle the metal plate.
CA 03030941 2019-01-15
14
In addition, fine concave and convex may be provided on
the surface of the metal plate 2, namely, on the surface of
the disc-shaped protrusion 2a of the metal plate 2 by sand
blasting or etching. This makes it possible to peel off the
nickel 4 electrodeposited on the protrusion 2a with a proper
impact without falling off the nickel 4 during the
electrolytic treatment. In this case, it is preferable that
the film thickness of the non-conductive film 3 to be
described later is two or more times the maximum surface
roughness Rz of the metal plate 2. There is concern that
pinholes and insulation failure portions are generated on the
non-conductive film 3 when the film thickness of the non-
conductive film 3 is thinner than two times the maximum
surface roughness Rz of the metal plate 2.
[Non-conductive film]
The non-conductive film 3 is formed on the flat area 2b,
which is the surface of the metal plate 2 except the
protrusion 2a, as illustrated in Fig. 2, and the surface of a
plurality of protrusions 2a disposed on the metal plate 2,
namely, the conductive portion 2c is put into a state of being
exposed by this. Moreover, the nickel 4 is formed by being
individually divided into a small blobby shape as the nickel 4
is electrodeposited and precipitated on such a conductive
portion 2c of the metal plate 2.
Here, in the cathode plate 1, the non-conductive film 3
is formed on the flat area 2b having a concave step formed by
the adjacent protrusions 2a and thus the non-conductive film 3
CA 03030941 2019-01-15
having a predetermined thickness is formed. In the cathode
plate 1 according to the present embodiment, the minimum film
thickness Y of the non-conductive film 3 is the same as or
greater than the height X of the protrusion 2a and it is
preferably the same as the height X.
Incidentally, the "minimum film thickness Y of the non-
conductive film" is defined as the minimum film thickness of
the non-conductive film 3 at a position between the centers of
the adjacent protrusions 2a. The non-conductive film 3 is
formed as the central portion between adjacent protrusions 2a
is piled by the surface tension as illustrated in Fig. 2A. In
this case, the minimum film thickness Y of the non-conductive
film 3 is the film thickness of the end portion in contact
with the side face of the protrusion 2a. In addition, the non-
conductive film 3 may be formed on the surface of the
protrusion 2a in a case in which the film thickness is thick.
As the minimum film thickness Y of the non-conductive film 3
at this time, not the film thickness of the non-conductive
film 3 formed on the surface of the protrusion 2a but the
minimum value among the film thicknesses of the non-conductive
films 3 formed at the position on the flat areas 2b is taken.
Incidentally, in the cathode plate 1, the film thickness
varies depending on the position of the protrusion 2a to be
selected but the minimum value among the film thicknesses is
taken as the minimum film thickness Y.
The non-conductive film 3 is formed on the flat area 2b
which is formed by the adjacent protrusions 2a and has a
CA 03030941 2019-01-15
16
concave step. Hence, the film thickness of the end portion of
the non-conductive film 3 is hardly thinned and the non-
conductive film 3 is hardly lost even by the stress at the
time of electrodeposition of the nickel 4 and the impact at
the time of peeling off of the nickel 4 after
electrodeposition as the conventional non-conductive film 13
illustrated in Fig. 6. In addition, the non-conductive film 3
does not protrude in a convex shape and the end portion
thereof is protected by the concave step as the conventional
non-conductive film 23 illustrated in Fig. 7. Consequently,
the impact to be applied to the end portion of the non-
conductive film 3 by the nickel 4 is minor and the non-
conductive film 3 is hardly lost even when the nickel 4 is
peeled off from the cathode plate 1. In this manner, in the
cathode plate 1, the non-conductive film 3 is hardly lost and
it is thus possible to repeatedly use the non-conductive film
3 in electrodeposition without replacing the non-conductive
film 3, to decrease the maintenance cost, and to achieve
improvement in the productivity.
Furthermore, the minimum film thickness Y of the non-
conductive film 3 is the same as or greater than the height X
of the protrusion 2a, and the nickel 4 can be thus peeled off
without being caught by the peripheral portion of the
protrusion 2a when the nickel 4 is peeled off from the cathode
plate 1. On the other hand, in a case in which the minimum
film thickness Y of the non-conductive film 3 is less than the
height X of the protrusion 2a as illustrated in Fig. 3, it is
CA 03030941 2019-01-15
17
difficult to peel off the electrodeposited nickel 4 since the
electrodeposited nickel 4 is caught by the peripheral portion
of the protrusion 2a, for example, at the place denoted by "A"
in the drawing when the electrodeposited nickel 4 is peeled
off from the cathode plate 1.
The upper limit of the minimum film thickness Y of the
non-conductive film 3 is not particularly limited, but the
difference (Y - X) between the minimum film thickness Y and
the height X of the protrusion 2a is preferably 200 pm or less,
more preferably 100 pm or less, still more preferably 50 pm or
less, and particularly preferably 5 pm or less. Here, as
described above, the minimum film thickness Y of the non-
conductive film 3 is not particularly limited as long as it is
the same as or greater than the height X of the protrusion 2a,
but it is not required to set the minimum film thickness Y
thicker than necessary. For example, it is difficult to coat
the non-conductive film 3 so as to have a film thickness
thicker than the height X of the protrusion 2a by more than
200 pm by screen printing. It is required to conduct coating
while finely adjusting the size of the pattern of the screen
plate plural times when it is attempted to form the non-
conductive film 3 having a film thickness thicker than the
height X of the protrusion 2a by more than 200 pm by screen
printing, and thus the adjustment is difficult and the
productivity decreases.
Incidentally, in a case in which the non-conductive film
3 is formed on the flat area 2b on the metal plate 2 by the
CA 03030941 2019-01-15
18
screen printing method, the material for the non-conductive
film 3 is coated on the surface of the protrusion 2a as well,
thus the surface area of the conductive portion 2c decreases
and the initial current density increases in some cases, but
there is no problem as long as troubles are not caused in the
characteristics of the electrodeposited nickel 4. In addition,
the non-conductive film 3 attached on the surface of the
protrusion 2a is likely to be lost since the film thickness
thereof is extremely thin, but the non-conductive film 3 to be
formed on the flat area 2b has no problem since the film
thickness thereof is thick and the loss thereof is suppressed.
The non-conductive film 3 is not particularly limited as
long as it is formed from a material which is non-conductive
and is less susceptible to corrosion by the electrolytic
solution to be used. For example, it is preferable that the
non-conductive film 3 is composed of a thermosetting resin or
a photocuring (ultraviolet curing and the like) resin from the
viewpoint of being easy to form the film. Specific examples
thereof may include an insulating resin such as an epoxy-based
resin, a phenol-based resin, a polyamide-based resin, or a
polyimide-based resin.
(2) Production of electric nickel using cathode plate
In the cathode plate 1 having the configuration described
above, the surface of the protrusion 2a to be exposed from the
non-conductive film 3 is the conductive portion 2c and the
nickel 4 is electrodeposited and precipitated thereon as
illustrated in Fig. 2B. In the cathode plate 1, the nickel 4
CA 03030941 2019-01-15
19
grows not only in the thickness direction but also in the
planar direction and is thus in the state of being piled on
the upper part of the non-conductive film 3. For this reason,
it is preferable to terminate the electrodeposition before the
nickel 4 grown from the conductive portion 2c of the surface
of the adjacent protrusion 2a comes into contact with each
other.
Thereafter, a plurality of pieces of blobby electric
nickel can be obtained from one cathode plate 1 by peeling off
the nickel 4 from the cathode plate 1 after the
electrodeposition of nickel is terminated. As described above,
in the cathode plate 1 according to the present embodiment,
the non-conductive film 3 is hardly lost and it is thus
possible to repeatedly use the non-conductive film 3 without
replacing the non-conductive film 3, to decrease the
maintenance cost, and to achieve improvement in the
productivity.
Incidentally, in the cathode plate 1 according to the
present embodiment, the nickel 4 is electrodeposited but
silver, gold, zinc, tin, chromium, cobalt, or any alloy
thereof may be electrodeposited without being limited to
nickel.
<2. Method for producing metal electrodeposition cathode
plate>
The method for producing a cathode plate 1 according to
the present embodiment includes a first step (Fig. 4A) of
forming a plurality of disc-shaped protrusions 2a on at least
CA 03030941 2019-01-15
one surface of a metal plate 2 and a second step (Fig. 4B) of
forming a non-conductive film 3 on the surface of the metal
plate 2 except the protrusions 2a as illustrated in Fig. 4.
[First step]
In the first step, a plurality of disc-shaped protrusions
2a is formed on the surface of the metal plate 2. For example,
the parts of the flat plate-shaped metal plate 2 except the
protrusions 2a are scraped, the protrusions 2a having a height
X are left, and flat areas 2b are thus formed. The processing
method is not particularly limited, and the formation of flat
areas 2b can be conducted by, for example, wet etching
processing, end mill processing, and laser processing.
For example, in the case of processing a flat plate-
shaped stainless steel plate by wet etching, a photosensitive
etching resist is coated on the surface of a stainless steel
plate and is then exposed by passing through a film or glass
on which a desired pattern is drawn and the etching resist of
the part to be etched is removed by a development treatment.
Thereafter, the stainless steel plate developed is dipped in
an etching solution (for example, a ferric chloride solution),
a part of the stainless steel plate from which the etching
resist has been removed is removed, and finally, the etching
resist is peeled off, whereby a plurality of disc-shaped
protrusions 2a matching with a desired pattern can be formed.
Incidentally, the protrusions 2a may be formed only on
one surface of the metal plate 2 or on both surfaces of the
metal plate 2.
CA 03030941 2019-01-15
21
[Second step]
In the second step, the non-conductive film 3 is formed
on the flat areas 2b to be the surface of the metal plate 2
except the protrusions 2a. The method for forming the non-
conductive film 3 is not particularly limited, and the
formation of the non-conductive film 3 can be conducted by
screen printing. In a case in which the material for the non-
conductive film 3 is a thermosetting resin or a photocurable
resin, heat curing or photocuring may be conducted if
necessary.
At this time, the non-conductive film 3 is formed so that
the minimum film thickness Y of the non-conductive film 3 at
the position between the centers of adjacent protrusions 2a is
the same as or greater than the height X of the protrusion 2a.
In a case in which a desired film thickness cannot be obtained
by one time of screen printing, the above-described screen
printing and heat curing or photocuring may be repeated until
the desired film thickness is obtained.
According to the method for producing a cathode plate
according to the present embodiment, it is possible to obtain
the cathode plate 1 in which the non-conductive film on the
metal plate is hardly lost and which can be repeatedly used.
EXAMPLES
Hereinafter, the present invention will be described more
specifically with reference to Examples, but the present
invention is not limited by these Examples at all. It should
CA 03030941 2019-01-15
22
be noted that members having the same functions as the members
illustrated in Fig. 1 to Fig. 6 are denoted by the same
reference numerals for the sake of convenience.
<Fabrication of cathode plate>
[Example 1]
A cathode plate 1 as illustrated in Fig. 1 and Fig. 2 was
fabricated. Specifically, first, a metal plate 2 which was
made of stainless steel and had a size of 200 mm x 100 mm x 4
mm was subjected to wet etching to form disc-shaped
protrusions 2a (18 pieces). At this time, the size of the
protrusion 2a was set to a diameter of 14 mm and a height X of
300 pm, and the minimum center-distance between adjacent
protrusions 2a was set to 21 mm.
Next, a thermosetting epoxy resin was coated on flat
areas 2b of the metal plate 2 by a screen printing method and
cured by heating at 150 C for 60 minutes to form a non-
conductive film 3. In the cathode plate 1 fabricated in this
manner, the difference between the minimum film thickness Y of
the non-conductive film 3 and the height X of the protrusion
at a position between the centers of adjacent protrusions 2a
was measured at arbitrary 10 places by using a laser
displacement meter, and the results were in a range of from 40
to 70 pm and the minimum film thickness Y of the non-
conductive film 3 was thus 340 pm.
[Example 2]
A cathode plate I was fabricated in the same manner as in
Example 1 except that the height X of the protrusion 2a of the
CA 03030941 2019-01-15
23
metal plate 2 was set to 500 pm and the non-conductive film 3
was formed on the flat area 2b so as to have a predetermined
thickness. In the cathode plate 1 fabricated in this manner,
the difference between the minimum film thickness Y of the
non-conductive film 3 and the height X of the protrusion 2a
was measured at arbitrary 10 places by using a laser
displacement meter, and the results were in a range of from 10
to 50 pm and the minimum film thickness Y of the non-
conductive film 3 was thus 510 pm.
[Example 3]
A cathode plate 1 was fabricated in the same manner as in
Example 1 except that the height X of the protrusion 2a of the
metal plate 2 was set to 60 pm and the non-conductive film 3
was formed on the flat area 2b so as to have a predetermined
thickness. In the cathode plate 1 fabricated in this manner,
the difference between the minimum film thickness Y of the
non-conductive film 3 and the height X of the protrusion was
measured at arbitrary 10 places by using a laser displacement
meter, and the results were in a range of from 60 to 90 pm and
the minimum film thickness Y of the non-conductive film 3 was
thus 120 pm.
[Example 4]
A cathode plate 1 was fabricated in the same manner as in
Example 1 except that the height X of the protrusion 2a of the
metal plate 2 was set to 100 pm and the non-conductive film 3
was formed on the flat area 2b so as to have a predetermined
thickness. In the cathode plate 1 fabricated in this manner,
CA 03030941 2019-01-15
24
the difference between the minimum film thickness Y of the
non-conductive film 3 and the height X of the protrusion was
measured at arbitrary 10 places by using a laser displacement
meter, and the results were in a range of from 100 to 150 pm
and the minimum film thickness Y of the non-conductive film 3
was thus 200 pm.
[Example 5]
A cathode plate 1 was fabricated in the same manner as in
Example 1 except that the height X of the protrusion 2a of the
metal plate 2 was set to 40 pm and the non-conductive film 3
was formed on the flat area 2b so as to have a predetermined
thickness. In the cathode plate 1 fabricated in this manner,
the difference between the minimum film thickness Y of the
non-conductive film 3 and the height X of the protrusion 2a
was measured at arbitrary 10 places by using a laser
displacement meter, and the results were in a range of from 10
to 40 pm and the minimum film thickness Y of the non-
conductive film 3 was thus 50 pm.
[Comparative Example 1]
In Comparative Example 1, a conventional cathode plate 11
as illustrated in Fig. 5 and Fig. 6 was fabricated.
Specifically, a thermosetting epoxy resin was coated on a flat
plate-shaped metal plate 12 which was made of stainless steel
and had a size of 200 mm x 100 mm x 4 mm except conductive
portions 12a (18 pieces) having a diameter of 14 mm by a
screen printing method and cured by heating at 150 C for 60
minutes to form a non-conductive film 13, whereby the cathode
CA 03030941 2019-01-15
plate 11 was fabricated. In the cathode plate 11 fabricated in
this manner, the maximum film thickness of the non-conductive
film 13 was measured at arbitrary 10 places by using a laser
displacement meter, and the results were in a range of from 90
to 110 pm.
[Comparative Example 2]
A cathode plate was fabricated in the same manner as in
Example 1 except that the height X of the protrusion of the
metal plate was set to 300 pm and the non-conductive film was
formed on the flat area so as to have a predetermined
thickness. In the cathode plate fabricated in this manner, the
difference between the minimum film thickness of the non-
conductive film and the height of the protrusion was measured
at arbitrary 10 places by using a laser displacement meter,
and the results were in a range of from -200 to -150 pm and
the minimum film thickness Y of the non-conductive film 3 was
thus 300 pm. Incidentally, the minimum film thickness Y of the
non-conductive film 3 is thinner than 500 pm of the height of
the protrusion.
[[Comparative Example 3]
A metal plate which was made of stainless steel and had a
size of 200 mm x 100 mm x 4 mm was subjected to wet etching to
form protrusions (18 pieces) having a height of 2000 pm.
However, warpage of the metal plate was severe and it was
difficult to form a non-conductive film by screen printing.
<Production of electric nickel>
Electric nickel was produced by an electrolytic treatment
CA 03030941 2019-01-15
26
using the cathode plates fabricated in the respective Examples
and Comparative Examples. Specifically, the cathode plate and
an anode plate which was composed of electric nickel and had a
size of 200 mm x 100 mm x 10 mm were dipped in an electrolytic
tank containing a nickel chloride electrolytic solution so as
to face each other. Thereafter, nickel was electrodeposited on
the surface of the cathode plate under the conditions of an
initial current density of 710 A/m2 and an electrolysis time of
3 days. After the electrolysis, the electric nickel
precipitated on the cathode plate was peeled off to obtain
blobby electric nickel for plating.
<Evaluation>
The number of times, by which the cathode plate used in
the electrolysis treatment was able to be repeatedly utilized
as it was, was evaluated. Nickel electrodeposited at the
adjacent protrusions and conductive portions are connected to
each other and electric nickel having a desired shape cannot
be obtained in some cases when the loss of the non-conductive
film expands. Hence, the use was stopped and the number of
repetitions up to this time point was evaluated in a case in
which the non-conductive film was lost from the boundary with
the protrusion in the direction of the flat area by 1 mm or
more. In addition, the use was .stopped and the number of
repetitions up to this time point was evaluated in a case in
which the non-conductive film was lost and the diameter of the
conductive portion increased by 1 mm or more as well.
The evaluation results are presented in the following
CA 03030941 2019-01-15
27
Table 1 together with the configuration of the cathode plate.
[Table 1]
Height X of Minimum film Maximum film
Y-X Number of
protrusion thickness Y thickness
[pm] repeated use
(Pm] [pm) fuml
Example 1 300 340 40 20 or more
Example 2 500 510 10 20 or more
Example 3 60 120 60 16
Example 4 100 200 100 20 or more
Example 5 40 50 10 9
Comparative
90-113 7
Example 1
comparative (Difficult
500 300 -200
Example 2 to peel off)
As presented in Table 1, in Examples 1 to 5 using the
cathode plates 1 in which the non-conductive film 3 was formed
on the flat area 2b of the metal plate 2 and the minimum film
thickness Y of the non-conductive film 3 was the same as or
greater than the height X of the protrusion 2a, loss of the
non-conductive film 3 was suppressed and it was possible to
sufficiently repeatedly use the cathode plates 1. Particularly,
in Examples 1 to 4 in which the height X of the protrusion 2a
was 50 pm or more, the number of repeated use was more than 10
times.
On the other hand, in Comparative Example 1 in which the
non-conductive film 13 was formed in a convex shape on the
flat plate-shaped metal plate 12, the non-conductive film was
lost and it was not possible to sufficiently repeatedly use
the cathode plate. In addition, in Comparative Example 2 in
which the minimum film thickness Y of the non-conductive film
CA 03030941 2019-01-15
28
was less than the height X of the protrusion, nickel was
caught by the peripheral portion of the protrusion at the time
of peeling off of nickel and it was difficult to peel off
nickel.
EXPLANATION OF REFERENCE NUMERALS
1 CATHODE PLATE
2 METAL PLATE
2a PROTRUSION
2b FLAT AREA
2c CONDUCTIVE PORTION
3 NON-CONDUCTIVE FILM
4 NICKEL
