U.S. patent application number 12/594919 was filed with the patent office on 2010-06-24 for copper alloy composite and method for manufacturing same.
This patent application is currently assigned to TAISEI PLAS CO., LTD.. Invention is credited to Naoki Ando, Masanori Naritomi.
Application Number | 20100159196 12/594919 |
Document ID | / |
Family ID | 39863910 |
Filed Date | 2010-06-24 |
United States Patent
Application |
20100159196 |
Kind Code |
A1 |
Naritomi; Masanori ; et
al. |
June 24, 2010 |
COPPER ALLOY COMPOSITE AND METHOD FOR MANUFACTURING SAME
Abstract
An integrated product whose joint strength between a copper
alloy and a carbon fiber prepreg is extremely high. A copper alloy
given a certain special surface shape yields tremendous bonding
strength through compatibility with an epoxy resin adhesive. With a
composite part in which this technology is utilized to integrate a
copper alloy member as a cover material with a CFRP, it is possible
to take advantage of the characteristics of both the copper alloy
and the FRP due to the tremendous bonding strength. In a step in
which an FRP prepreg is put into a mold and heated and cured,
usually the mold is first coated with a release agent to facilitate
release from the mold, but with high-technology CFRP, bleeding of
the release agent often diminishes the properties. A copper alloy
sheet 21 is used as a cover material, and a CFRP 22 is cured.
Inventors: |
Naritomi; Masanori; (Tokyo,
JP) ; Ando; Naoki; (Tokyo, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW, SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
TAISEI PLAS CO., LTD.
Tokyo
JP
|
Family ID: |
39863910 |
Appl. No.: |
12/594919 |
Filed: |
April 4, 2008 |
PCT Filed: |
April 4, 2008 |
PCT NO: |
PCT/JP2008/056820 |
371 Date: |
December 16, 2009 |
Current U.S.
Class: |
428/141 ; 216/7;
977/773 |
Current CPC
Class: |
B32B 3/18 20130101; B32B
2264/101 20130101; C23F 1/18 20130101; B32B 27/322 20130101; B29K
2995/0072 20130101; Y10T 428/31678 20150401; B32B 37/02 20130101;
B32B 2605/00 20130101; Y10T 428/24997 20150401; B32B 2255/06
20130101; B29K 2705/10 20130101; B32B 27/32 20130101; B32B 7/12
20130101; B32B 15/20 20130101; B32B 27/04 20130101; B32B 27/06
20130101; B32B 2262/101 20130101; B32B 2262/106 20130101; B32B
2457/00 20130101; B32B 2307/302 20130101; B32B 2255/26 20130101;
B32B 2605/18 20130101; B29C 70/088 20130101; Y10T 428/24355
20150115; B32B 2262/0269 20130101; B32B 2264/104 20130101; B32B
2260/046 20130101; B32B 2264/102 20130101; B32B 2605/12 20130101;
B32B 2260/021 20130101; B32B 15/14 20130101; B32B 2535/00 20130101;
B32B 2307/714 20130101 |
Class at
Publication: |
428/141 ; 216/7;
977/773 |
International
Class: |
B32B 3/00 20060101
B32B003/00; C23F 1/00 20060101 C23F001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 6, 2007 |
JP |
2007-100727 |
Claims
1. A copper alloy composite, comprising: a copper alloy part having
micron-order roughness produced by chemical etching, whose surface,
when observed by electron microscope, has ultrafine texturing in
which holes or depressions that are circular in shape with a
diameter of 10 to 150 nm or elliptical in shape with an average of
major and minor diameters of 10 to 150 nm are present over
substantially the entire surface at an irregular spacing of 30 to
300 nm, the surface being mainly a thin layer of cupric oxide; and
an adherend that is bonded using, as an adhesive, an epoxy adhesive
that has permeated the ultrafine texturing.
2. A copper alloy composite, comprising: a copper alloy part having
micron-order roughness produced by chemical etching, whose surface,
when observed by electron microscope, has ultrafine texturing in
which bumps that are circular in shape with a diameter of 10 to 200
nm or elliptical in shape with an average of major and minor
diameters of 10 to 200 nm are present over substantially the entire
surface, the surface being mainly a thin layer of cupric oxide; and
an adherend that is bonded using, as an adhesive, an epoxy adhesive
that has permeated the ultrafine texturing.
3. A copper alloy composite, comprising: a copper alloy part having
micron-order roughness produced by chemical etching, substantially
the entire surface of which is covered with, when observed by
electron microscope, ultrafine texturing in which granules or
amorphous polygons with a diameter of 10 to 150 nm are lined up and
partially melted together in a stacked shape, the surface being
mainly a thin layer of cupric oxide; and an adherend that is bonded
using, as an adhesive, an epoxy adhesive that has permeated the
ultrafine texturing.
4. A copper alloy composite, comprising: a copper alloy part having
micron-order roughness produced by chemical etching, substantially
the entire surface of which is covered with, when observed by
electron microscope, ultrafine texturing in the form of gullies on
the slope of a lava plateau, in which granules with a diameter of
10 to 20 nm and amorphous polygons with a diameter of 50 to 150 nm
are mixed together in a stacked shape, the surface being mainly a
thin layer of cupric oxide; and an adherend that is bonded using,
as an adhesive, an epoxy adhesive that has permeated the ultrafine
texturing.
5. The copper alloy composite according to any of claims 1 to 4,
wherein the adherend is a copper alloy part which is made of a
copper alloy and on which the ultrafine texturing has been
formed.
6. The copper alloy composite according to any of claims 1 to 4,
wherein the adherend is a fiber-reinforced plastic that contains
the epoxy adhesive and has been reinforced by filling and layering
at least one type selected from long fibers, short fibers and fiber
cloth.
7. The copper alloy composite according to any of claims 1 to 4,
wherein the micron-order surface roughness is such that the mean
length of a roughness curve (RSm) is 0.8 to 10 .mu.m and the
maximum height of roughness (Rz) is 0.2 to 5 .mu.m.
8. The copper alloy composite according to any of claims 1 to 4,
wherein the resin component of the cured epoxy resin contains no
more than 30 weight parts elastomer component per 100 weight parts
of total resin component.
9. The copper alloy composite according to any of claims 1 to 4,
wherein the cured epoxy resin contains a total of no more than 50
weight parts filler per 100 weight parts of total resin
component.
10. The copper alloy composite according to claim 9, wherein the
filler is one type selected from reinforcing fibers of glass fiber,
carbon fiber, and aramid fiber, and at least one type selected from
powder fillers of calcium carbonate, magnesium carbonate, silica,
talc, clay, and glass.
11. The copper alloy composite according to claim 8, wherein the
elastomer component is at least one type selected from vulcanized
rubber powders with a particle size of 1 to 30 .mu.m,
semi-crosslinked rubber, unvulcanized rubber, terminal-modified
thermoplastic resins in which the melt softening point of a
hydroxyl group terminated polyether sulfone is at least 300.degree.
C., and polyolefin resins.
12. A method for manufacturing a copper alloy composite,
comprising: a step of shaping a copper alloy part by machining or
the like from a casting or an intermediate material; a chemical
etching step of immersing the shaped copper alloy part in an acidic
aqueous solution containing an oxidant; a surface hardening step of
immersing the chemically etched copper alloy part in a strongly
basic aqueous solution containing an oxidant; a step of coating the
necessary portions of the copper alloy part with an uncured epoxy
resin; a step of adjusting a prepreg of a fiber-reinforced plastic
to the required size; a step of applying the prepreg to the coated
side of the copper alloy part; and a step of positioning the
prepreg and the copper alloy part, and heating the prepreg and the
copper alloy part while holding them down, to cure the epoxy resin
component.
13. A method for manufacturing a copper alloy composite,
comprising: a step of shaping a copper alloy part by machining or
the like from a casting or an intermediate material; a chemical
etching step of immersing the shaped copper alloy part in an acidic
aqueous solution containing an oxidant, to form ultrafine texturing
on the surface thereof; a surface hardening step of immersing the
chemically etched copper alloy part in a strongly basic aqueous
solution containing an oxidant; a step of coating the necessary
portions of the copper alloy part with an uncured epoxy resin; a
hardening pretreatment step of putting the copper alloy part that
has been coated with the uncured epoxy resin in a sealed vessel,
depressurizing, and then pressurizing to force the uncured epoxy
resin into the ultrafine texturing on the copper alloy surface; a
step of adjusting a prepreg of a fiber-reinforced plastic to the
required size; a step of applying the prepreg of a fiber-reinforced
plastic to the coated side of the copper alloy part; and a step of
positioning the prepreg and the copper alloy part, and heating the
prepreg and the copper alloy part while holding them down, to cure
the epoxy resin component.
Description
TECHNICAL FIELD
[0001] This invention relates to a copper alloy composite used in
moving machinery, electrical devices, medical devices, general
machinery, and other such devices, and a method for manufacturing
this composite. More specifically, this invention relates to a
novel, fundamental copper alloy composite used in parts for
automobiles, aircraft, ships, and other such moving machinery,
structures, and so forth, and a method for manufacturing this
composite, and more particularly relates to a copper alloy
composite that makes use of both a copper alloy part and a
fiber-reinforced plastic part, and a method for manufacturing this
composite.
BACKGROUND ART
[0002] Techniques for integrating metal and metal, or metal and
resin, is needed in a wide range of fields, such as the manufacture
of parts used in automobiles, household electrical products,
industrial machinery, and so forth, and many different adhesives
have been developed for this purpose. Of these, some extremely good
adhesives have been commercially available and are in use. For
example, adhesives that exhibit their function at normal
temperature or when heated are used to bond and integrate metals
with synthetic resins, and this method is the standard bonding
method in use today.
[0003] Meanwhile, bonding methods that do not involve the use of an
adhesive have been researched. An example is a method in which a
high-strength engineering plastic is integrated with a light metal
such as magnesium, aluminum, or an alloy of these, or an iron alloy
such as stainless steel, without any adhesive being interposed
between the materials. For instance, as a method for simultaneously
bonding by injection or another such method (hereinafter referred
to as "injection bonding"), a manufacturing technique has been
developed in which a polybutylene terephthalate resin (hereinafter
referred to as PBT) or a polyphenylene sulfide resin (hereinafter
referred to as PPS) is injection bonded to an aluminum alloy (see
Patent Documents 1 and 2, for example). In addition, it has been
proven in the past that magnesium alloys, copper alloys, titanium
alloys, stainless steel, and the like can be injection bonded by
using a similar type of resin (Patent Documents 3, 4, 5 and 6).
[0004] These inventions were all made by the present inventors, but
they are based on simple bonding theory. These are the "NMT" theory
related to the injection bonding of aluminum alloys, and the "new
NMT" theory related to the injection bonding of all metal alloys.
One of the present inventors, Ando, who is the creator of the "new
NMT" theory that can be used in a broader sense, has described the
theory as follows. To produce injection bonding and its tremendous
bonding strength, various conditions pertain to both the metal
alloy side and the injected resin side, and starting with the metal
side, the following three conditions have to be met. Condition (1)
is that the metal alloy have a rough profile curve (roughness
curve) in which chemical etching produces a period (spacing)
between peaks or between valleys of 1 to 10 .mu.m, and the
peak-valley height difference is preferably about one-half this,
specifically, about 0.5 to 5 .mu.m.
[0005] Obtaining a rough surface such as this 100% by chemical
reaction is actually impossible; more specifically, condition (1)
is deemed to have been satisfied if a roughness curve can be
plotted in which the texturing appears at an irregular period
between 0.2 and 20 .mu.m and the maximum height difference thereof
is between 0.2 and 5 .mu.m, or if scanning analysis by scanning
probe microscope reveals a rough surface (roughness) in which the
mean width of the profile elements (RSm) of the profile curve
elements referred to in JIS standards (JIS B 0601:2001) is 0.8 to
10 .mu.m and the maximum height of the maximum height of profile
(maximum height roughness) (Rz) is 0.2 to 5 .mu.m. The present
inventors call this "a surface with micron-order roughness" for
short. There is also a condition (2), which is that there be the
above-mentioned large textured surface, or more precisely, a finely
textured surface with a period of at least 10 nm, and preferably 50
nm, on the inner walls of the depressions. The last one is
condition (3), which is that the surface that forms the fine
texturing have ceramic layer, or more specifically, a metal oxide
layer that is thicker than the natural oxidation layer, or an
intentionally produced metal phosphorus oxide layer. It is also
preferable if this hard layer is a thin layer with a thickness of
only a few nanometers to a few dozen nanometers.
[0006] The condition on the resin side is that it be a hard
crystalline resin, which can be compounded with another suitable
polymer, for example, to slow down the crystallization during
quenching. Actually, a resin composition in which another suitable
polymer and glass fibers have been compounded with PBT, PPS, or
another such crystalline resin can be used. These can be used to
perform injection bonding in an injection molding mold and a
standard injection molding machine; this process is described
according to the "new NMT" theory of the inventors. The injected
molten resin is guided into a mold whose temperature is about
150.degree. C. than the melting point of the resin, but it is seen
to be cooled in the runner and other channels and drop below its
melting point. Specifically, it will probably be understood that
even though the temperature drops below the melting point when a
molten crystalline resin is quenched, crystals of that resin are
produced and the resin changes into a solid in zero time.
[0007] In other words, a state in which the resin is molten while
being under its melting point, which is called a super-cooled
state, only exists for an extremely short time. With PBT or PPS
that has been specially compounded as discussed above, this
super-cooling time is thought to be slightly longer, and this was
utilized so that the resin would penetrate into the large
depressions on the micron-order metal before its viscosity was
sharply increased by the production of a large quantity of
microcrystals. The molten resin continues to cool even after
penetrating these depressions, and the number of microcrystals
increases and the viscosity rises sharply. Because of this, whether
or not the molten resin can reach the deepest part of the
depressions is determined by the size and shape of the depressions.
Experiment results indicate that regardless of the type of metal,
the resin penetrated quite far as long as the depressions had a
diameter of at least 1 .mu.m and a depth of 0.5 to 5 .mu.m.
Furthermore, if the inner walls of the depressions are rough when
viewed microscopically, part of the resin will also penetrate into
the gaps of this ultrafine texturing, and as a result, even if a
pull-out force is applied to the resin side, the resin will hang on
and be resistant to coming loose.
[0008] If this rough surface is a metal oxide, it will be hard and
have a hooking effect much like a spike. If the texturing period is
at least 10 .mu.m, the result will be weaker bonding, but the
reason for this is clear. Specifically, if we consider a cluster of
dimple-like depressions as an example, the larger is the depression
diameter, the fewer dimples there will be per unit of surface area,
and as the depressions become larger, the above-mentioned spike
(hook) latching effect is diminished. As to the bonding itself, it
is a question of the resin component and the metal alloy surface,
but when reinforcing fiber or an inorganic filler is added to a
resin composition, the coefficient of linear expansion of the resin
as a whole draws closer to that of a metal alloy, so it is easier
to maintain bonding strength after bonding. According to this
hypothesis, when a PBT or PPS resin or the like is injection bonded
to the surface of a magnesium alloy, copper alloy, titanium alloy,
stainless steel, or the like, the result is a strong integrated
material with a shear breaking force of 200 to 300 Kgf/cm.sup.2
(approximately 20 to 30 N/mm.sup.2, or 20 to 30 MPa).
[0009] The present inventors proved the "new NMT" theory to be true
by injection bonding many different metal alloys, but the
hypothesis used here is based on an assumption related to a
fundamental portion of polymer physical chemistry, and ordinarily
would have to be reviewed by many chemists and scientists. For
instance, the inventors have taken it upon themselves to discuss
molten crystalline resin during quenching, but as to whether or not
the crystallization rate really does drop, this was not something
that was debated in the past from the perspective of polymer
physics, and while it is believed to be true, frankly it has not
yet been proven. Specifically, this is a fast reaction that takes
place under high temperature and pressure, making direct
measurement impossible. Also, this hypothesis sets forth a
completely physical anchor effect theory for bonding, and is not in
complete agreement with conventional wisdom and standard theory.
Specifically, most of the current books written by specialists in
the field of adhesion ascribe this to chemical processes.
[0010] The present inventors resigned themselves to the difficulty
of direct experimentation that would lead to a proof of their
hypothesis, they decided to take an opposite approach.
Specifically, seeing that the "new NMT" theory can also be applied
to adhesive bonding, they determined to corroborate
high-performance adhesion by a similar theory. Namely, they used a
commercially available multi-purpose epoxy adhesive, varied only
the surface condition of the adherend, and sought to find a bonding
system that was heretofore unknown.
[0011] As to bonding with an adhesive agent, there has already been
wonderful progress, and this sophisticated technology has been put
to use in the assembly of aircraft. This technology involves a
surface treatment that imparts corrosion resistance and minute
texturing to a metal alloy, and the use of a high-performance
adhesive. However, when it is examined more closely, the surface
treatment of the metal seems to be treatment methods that were
developed over 40 years ago, such as phosphating, chromating, and
anodizing, and even today these methods are used as standard
procedure, so progress seems to have come to a halt. Meanwhile, as
to the development of the adhesives themselves, mass production of
instant adhesives began decades ago, and ever since the much-touted
debut of second-generation acrylic adhesives, there has been no
word of anything revolutionary.
[0012] As to adhesion theory, although the most recent scholarly
trends are not known to the present inventors, commercially
available books are a vague mix of chemical theory and physical
theory, making it seem unlikely that any significant progress will
be made in materials. The present inventors were fortunate enough
to be working in an era in which the electron microscope, which has
a resolution down to just a few nanometers, can be freely and
inexpensively used, and looking at these high-resolution
micrographs made it possible to come up with the hypotheses related
to "NMT" and "new NMT" injection bonding. As a result, they arrived
at the above-mentioned hypothesis based entirely on an anchor
effect. Consequently, it was anticipated that some new discovery
would be made if the physical aspect were given emphasis in
experiments into adhesion theory by adhesive bonding.
[0013] Meanwhile, copper and copper alloys have the best electrical
and thermal conductivity of all practical metals, and also have
excellent corrosion resistance. Their specific gravity is around
8.9, and while this makes them relatively heavy metals, they are
used in a vast range of applications because of their
above-mentioned performance. The present inventors have begun trial
production of relay case take-off terminals from tough pitch copper
C1100 copper alloy rod and PPS resin using an injection bonding
method that has already been developed (Patent Document 4), and
wondered if heat diffusers for mobile electronic devices and the
like, lead wire take-offs for anti-explosive devices, and other
such parts could be manufactured by using an adhesive agent, rather
than by injection bonding. In particular, when it comes to tensile
strength, carbon fiber reinforced plastic (hereinafter referred to
as CFRP) is one of the best of all structural materials, including
metals, and it is also super-light, with a specific gravity of 1.6
to 1.7. The inventors thought that parts that take advantage of
both light weight and the advantages of copper could be produced by
combining this CFRP with a copper alloy having a higher specific
gravity.
[0014] A CFRP prepreg is a weave or cluster of carbon fiber
(hereinafter referred to as CF) that has been impregnated with
uncured epoxy resin, and simultaneous curing is possible, and
integration is easy, if there is good compatibility with the epoxy
adhesive applied to the metal side. Therefore, in producing an
integrated product, the inventors felt that the first focus of
research and development should be how high the bonding strength
between a copper alloy and an epoxy adhesive could be increased and
how stable it could be made. A copper alloy also exhibits good
corrosion resistance even in seawater with a high salt content. And
not only is corrosion resistance good, but very little seaweed
adheres to copper parts in seawater and fresh water. For example,
it is known that if bacteria adhere to copper or silver coins, they
are killed, and this effect is attributed to the redox capability
of the tiny amounts of copper ions and silver ions that are
dissolved out. To put it another way, these metals are used as
coins because of this effect, and it is surmised that this is also
the reason why almost no seaweed adheres to the copper plates
attached to ships hulls.
[0015] It is common knowledge among seafarers that a ship with aged
hull paint will become completely covered in seaweed upon mooring
in port for just a few days in the summertime. Hull paint itself
releases ions of copper or tin in very small amounts at a time, and
although there have been improvements of late, it is still a vivid
memory that seawater fouling occurred with past hull paint with
good anti-seaweed performance. It can be readily understood that no
anti-seaweed paint would be necessary if an FRP ship covered with
thin copper plates could be manufactured. For example, FIG. 4 shows
the tip of a seaplane pontoon made of CFRP covered with a thin
copper alloy plate, which is an idea of the present inventors. It
is not known whether or not such ideas or specific challenges
existed in the past, but if a copper plating that could be
adhesively bonded to FRP at extremely high strength could be
obtained, it would not be difficult to product a practical pontoon
having such a structure.
[0016] Because of the above, an attempt was made to develop a
method for obtaining a strong bond with a fiber reinforced plastic
(hereinafter referred to as FRP), focusing on the development of
technology for the surface treatment copper alloys.
[0017] Patent Document 1: WO 03/064150 A1
[0018] Patent Document 2: WO 2004/041532 A1
[0019] Patent Document 3: PCT/JP2007/073526
[0020] Patent Document 4: PCT/JP2007/070205
[0021] Patent Document 5: PCT/JP2007/074749
[0022] Patent Document 6: PCT/JP2007/075287
DISCLOSURE OF THE INVENTION
[0023] The present invention adopts the following means for
achieving the stated object.
[0024] The copper alloy composite of present invention 1 is
composed of: a copper alloy part having micron-order roughness
produced by chemical etching, whose surface, when observed by
electron microscope, has ultrafine texturing in which holes or
depressions that are circular in shape with a diameter of 10 to 150
nm or elliptical in shape with an average of major and minor
diameters of 10 to 150 nm are present over substantially the entire
surface at an irregular spacing of 30 to 300 nm, the surface being
mainly a thin layer of cupric oxide; and an adherend that is bonded
using, as an adhesive, an epoxy adhesive that has permeated the
ultrafine texturing.
[0025] The copper alloy composite of present invention 2 is
composed of: a copper alloy part having micron-order roughness
produced by chemical etching, whose surface, when observed by
electron microscope, has ultrafine texturing in which bumps that
are circular in shape with a diameter of 10 to 200 nm or elliptical
in shape with an average of major and minor diameters of 10 to 200
nm are present over substantially the entire surface, the surface
being mainly a thin layer of cupric oxide; and an adherend that is
bonded using, as an adhesive, an epoxy adhesive that has permeated
the ultrafine texturing.
[0026] The alloy composite of present invention 3 is composed of: a
copper alloy part having micron-order roughness produced by
chemical etching, substantially the entire surface of which is
covered with, when observed by electron microscope, ultrafine
texturing in which granules or amorphous polygons with a diameter
of 10 to 150 nm are lined up and partially melted together in a
stacked shape, the surface being mainly a thin layer of cupric
oxide; and an adherend that is bonded using, as an adhesive, an
epoxy adhesive that has permeated the ultrafine texturing.
[0027] The alloy composite of present invention 4 is composed of: a
copper alloy part having micron-order roughness produced by
chemical etching, substantially the entire surface of which is
covered with, when observed by electron microscope, ultrafine
texturing in the form of gullies on the slope of a lava plateau, in
which granules with a diameter of 10 to 20 nm and amorphous
polygons with a diameter of 50 to 150 nm are mixed together in a
stacked shape, the surface being mainly a thin layer of cupric
oxide; and an adherend that is bonded using, as an adhesive, an
epoxy adhesive that has permeated the ultrafine texturing.
[0028] The method for manufacturing the copper alloy composite of
present invention 1 comprises a step of shaping a copper alloy part
by machining or the like from a casting or an intermediate
material, a chemical etching step of immersing the shaped copper
alloy part in an acidic aqueous solution containing an oxidant, a
surface hardening step of immersing the chemically etched copper
alloy part in a strongly basic aqueous solution containing an
oxidant, a step of coating the necessary portions of the copper
alloy part with an uncured epoxy resin, a step of adjusting a
prepreg of a fiber-reinforced plastic to the required size, a step
of applying the prepreg to the coated side of the copper alloy
part, and a step of positioning the prepreg and the copper alloy
part, and heating the prepreg and the copper alloy part while
holding them down, to cure the epoxy resin component.
[0029] The method for manufacturing the copper alloy composite of
present invention 2 comprises a step of shaping a copper alloy part
by machining or the like from a casting or an intermediate
material, a chemical etching step of immersing the shaped copper
alloy part in an acidic aqueous solution containing an oxidant, to
form ultrafine texturing on the surface thereof, a surface
hardening step of immersing the chemically etched copper alloy part
in a strongly basic aqueous solution containing an oxidant, a step
of coating the necessary portions of the copper alloy part with an
uncured epoxy resin, a hardening pretreatment step of putting the
copper alloy part that has been coated with the uncured epoxy resin
in a sealed vessel, depressurizing, and then pressurizing to force
the uncured epoxy resin into the ultrafine texturing on the copper
alloy surface, a step of adjusting a prepreg of a fiber-reinforced
plastic to the required size, a step of applying the prepreg of a
fiber-reinforced plastic to the coated side of the copper alloy
part, and a step of positioning the prepreg and the copper alloy
part, and heating the prepreg and the copper alloy part while
holding them down, to cure the epoxy resin component.
[0030] The various elements of the present invention mentioned
above will now be described in detail.
[0031] Copper Alloy Part
[0032] The "copper" and "copper alloy" used in the present
invention refer to copper, brass, phosphor bronze, nickel silver,
aluminum bronze, and the like, and apply to all copper alloys,
including pure copper alloys such as C1020 and C1100 set forth in
the Japanese Industrial Standards (JIS H 3000 series), C2600-series
brass alloys, C5600-series cupro-nickel alloys, and other copper
alloys developed for various applications, including iron alloys
used for connectors. Also applicable are plastically worked
products that are intermediate materials of these, such as
sheeting, strip, tubing, rod, and wire, which are subjected to
cutting, stamping, or other mechanical working to obtain a part in
the desired shape, as well as forged parts and so forth.
[0033] Surface Treatment/Pretreatment/Chemical Etching of Copper
Alloy Part
[0034] The copper alloy part is preferably first immersed in a
degreasing tank in which oil and fingerprints are removed from the
surface mechanically. More specifically, it is preferable if a
commercially available copper alloy degreaser is put in water in
the concentration indicated by the chemical manufacturer to prepare
an aqueous solution, and the copper alloy part is immersed in this
and rinsed with water, but it is also possible to use a
commercially available degreaser for iron, stainless steel,
aluminum, or the like, as well as an aqueous solution obtained by
dissolving an industrial-use or household-use neutral detergent.
More specifically, it is preferable if a commercially available
degreaser or neutral detergent is dissolved in water in a
concentration of from a few percent to 5%, and the copper alloy
part is soaked for 5 to 10 minutes at 50 to 70.degree. C. and then
rinsed with water.
[0035] Next, preliminary base washing is preferably performed, in
which the copper alloy part is immersed in a caustic soda aqueous
solution with a concentration of a few percent and maintained at
about 40.degree. C., after which it is rinsed with water. It is
also preferable if the copper alloy part is immersed in an aqueous
solution containing hydrogen peroxide and sulfuric acid, then
rinsed with water and chemically etched. This chemical etching
preferably involves the use of an aqueous solution containing a few
percent of both sulfuric acid and hydrogen peroxide between
20.degree. C. and close to normal temperature. The immersion time
here will vary with the type of alloy, but ranges from a few
minutes to 20 minutes. In these pretreatment steps, the resulting
copper alloy will have a roughness that is favorable for most
copper alloys, specifically, it will have texturing with an
irregular period between 0.2 and 20 .mu.m, and the maximum height
difference of this texturing will be about 0.2 to 10 .mu.m, or will
be such that analysis by scanning probe microscope reveals a mean
length (RSm) of the roughness curve referred to in JIS standards
(JIS B 0601:2001 (ISO 4287)) is 0.8 to 10 .mu.m and the maximum
height roughness (Rz) is 0.2 to 10 .mu.m. Preferably, the maximum
height roughness (Rz) is 0.2 to 5 .mu.m.
[0036] However, and this is particularly true with a pure
copper-based copper alloy, the rough surface obtained as a result
of the above-mentioned chemical etching also often results in a
texturing period of over 10 .mu.m, and the mean value thereof (RSm)
is greater than that of other copper alloys besides those based on
pure copper. On the other hand, given the large RSm, the texturing
height difference is small. In particular, with C1020 (oxygen-free
copper) and the like that have a high copper purity, it is clear
that the metal crystal grain size is large, and obviously often
gives a roughness curve with a large period as mentioned above, and
it was surmised that there is a direct correlation between
texturing period and the metal crystal grain size. With chemical
etching performed not only with pure copper alloys, but also with
various other metals, it is surmised that most of the etching can
probably be attributed to the fact that corrosion starts from the
crystal grain boundaries. At any rate, even if the texturing period
is on the micron order, if the texturing height difference is small
in proportion to that period, the present invention will tend not
to have as much of an effect. Consequently, if it is felt that
there is inadequate roughness of large texturing, a corresponding
treatment is preferably carried out, which will be discussed
below.
[0037] Surface Treatment of Copper Alloy Part: Surface Hardening
Treatment
[0038] After undergoing pretreatment, the copper alloy part is
oxidized. In the electronic parts industry, there is a known method
called a blackening treatment; the oxidation performed in the
present invention, although it differs in its purpose and extent of
oxidation, is the same as far as the step itself is concerned.
Chemically speaking, the surface layer of the copper alloy is
oxidized by an oxidant under strongly basic conditions. When a
copper atom is ionized by an oxidant, if the surroundings are
strongly basic, the atom will turn into black cupric oxide without
dissolving in the aqueous solution. When a copper alloy part is
used as a heat sink or heat generating material part, the surface
is blackened in order to improve the efficiency of the dissipation
or absorption of radiant heat, and this treatment is called a
blackening treatment in the electronic parts industry where copper
is used. This blackening treatment can be utilized for the surface
treatment of the present invention. The purpose of this blackening
treatment, however, is to create a surface that is hard and has
ultrafine texturing on the nano-order on a copper alloy part that
has roughness, so it is not literally blackening.
[0039] A commercially available blackening agent can be used at the
concentration and temperature recommended by the manufacturer, but
the immersion time in this case is far shorter than during
so-called blackening. Actually, the immersion time is adjusted by
observing the obtained alloy under an electron microscope. The
present inventors found that it is preferable to use an aqueous
solution containing about 5% sodium chlorite and about 10% caustic
soda, at 60 to 70.degree. C., and that it is preferable in that
case for the immersion time to be about 0.5 to 1.0 minute. This
procedure covers the copper alloy with a thin layer of cupric
oxide, the surface of which is rough, with a roughness on the
micron order, and when this is observed under an electron
microscope, it is seen that there are formed in this rough surface
circular holes with a diameter of 20 to 150 nm, or elliptical holes
with a major or minor diameter of 20 to 150 nm.
[0040] The openings of these circular or elliptical holes are in
the form of ultrafine texturing that is present over the entire
surface at a period of 100 to 200 nm (an example of this is shown
in the photograph of FIG. 5). The crux of the matter is that when
this surface hardening treatment is performed, ultrafine texturing
and a surface hardened layer are both obtained at the same time. It
was also effectively found that if the immersion time in the
above-mentioned treatment solution is increased to 2 to 3 minutes,
for example, the surface hardening treatment will be excessive, and
will actually weaken bonding strength, so this is undesirable.
[0041] Surface Treatment of Copper Alloy Part: Repeated
Treatment
[0042] With the etching of a pure copper-based copper alloy
discussed above, observational results have revealed a definite
pattern in which the corrosion of the copper occurs from the metal
crystal grains, and as mentioned above, when the crystal grain size
is particularly large, that is, with oxygen-free copper (C1020),
good bonding strength cannot be achieved by the above-mentioned
chemical etching and surface hardening treatment alone. In short,
depressions of the most important size were not produced as
anticipated.
[0043] The inventors discovered a method for dealing with such
situations. The result is an extremely simple method, in which a
surface hardening treatment (blackening) is first performed, after
which this product is again immersed for a short time in the
etching solution and re-etched, after which it is again blackened.
As a result, the period of micron-order roughness approached about
10 .mu.m or less, as anticipated, and observation by electron
microscope showed that the ultrafine texturing looked the same as
when this repeated treatment was not performed.
[0044] Adherend
[0045] The adherend referred to in the present invention may be
made of any material, but means a copper alloy part made of a
copper alloy which has been treated as above to form ultrafine
texturing, an FRP composed of long fiber, short fiber, a fiber
cloth, or the like and containing an epoxy adhesive, and so on.
[0046] Epoxy Resin (Adhesive) and Application Thereof
[0047] There are some outstanding commercially available products
for the epoxy adhesive itself. Even if it is produced in house, the
raw materials can be easily found for sale. Specifically,
commercially available bisphenol-type epoxy resins,
glycidylamine-type epoxy resins, polyfunctional polyphenol-type
epoxy resins, alicyclic epoxy resins, and so forth are commercially
available, and all can be used as the material used in the present
invention. Also, these epoxy resins can be linked together by
reacting them with a polyfunctional third component, such as a
polyfunctional oligomer having a plurality of hydroxyl groups, and
this product can be used. It is preferable to add a polyfunctional
amine compound as a curing agent to one of these epoxy resins, and
mix these to obtain an epoxy adhesive.
[0048] Adding a filler component, elastomer component, or the like
to the cured epoxy resin is preferable because the coefficient of
linear expansion will be on a par with that of an aluminum alloy,
and with that of a CFRP material, and the result can serve as a
cushioning material if subjected to temperature shock. It is
preferable for the elastomer component to be contained in an amount
of 0 to 30 weight parts, and specifically no more than 30 weight
parts, per combined 100 weight parts of the above-mentioned resin
component (epoxy resin component+curing agent component), because
this will improve impact resistance and temperature shock
resistance. It is undesirable for the amount to be greater than 30
weight parts because the bonding strength will decrease. One
elastomer component is a vulcanized rubber powder with a particle
size of 1 to 15 .mu.m. If the size is a diameter of a few microns,
the particles will be too large to penetrate into the ultrafine
texturing on the aluminum alloy when the adhesive is applied, which
means that they will not affect the anchor portion, and will merely
remain in the adhesive layer. Therefore, they have the role of
resisting temperature shock without lowering bonding strength.
[0049] Any kind of vulcanized rubber can be used, but actually it
is difficult to pulverize it down to a size of just a few microns,
regardless of the type of rubber. As far as the inventors could
find, there has not been much research and development into methods
for manufacturing vulcanized rubber microparticles. The inventors
adopted a method in which a vulcanized rubber or unvulcanized
rubber and a thermoplastic resin are cooled with liquid nitrogen,
then mechanically pulverized and graded. Unfortunately, the
manufacturing efficiency and cost here are not really at a
commercial level. Another thing is the use of unvulcanized or
semi-crosslinked rubber, and modified super engineering plastics,
polyolefin resins, and so forth. An example of a super engineering
plastic is "PES 100P" a hydroxy-terminated polyether sulfone made
by Mitsui Chemical. Also, polyolefin resins that readily mix with
epoxy resins have already been developed, and these can be used
favorably.
[0050] The inventors have seen that durability with respect to the
temperature shock is theoretically inferior to that of powdered
unvulcanized rubber, but in actual practice it is still not
entirely clear. The evaluation method itself has not been
completely perfected with the method of the present inventors. At
any rate, even with these unvulcanized elastomers, temperature
shock resistance is better when they are admixed. Polyolefin resins
such as this include maleic anhydride-modified ethylenic
copolymers, glycidyl methacrylate-modified ethylenic copolymers,
glycidyl ether-modified ethylene copolymers, ethylene alkyl
acrylate copolymers, and so forth. Examples of these maleic
anhydride-modified ethylenic copolymers include maleic
anhydride-graft modified ethylene copolymers, maleic
anhydride-ethylene copolymers, and ethylene-acrylic acid
ester-maleic anhydride ternary copolymers. Of these, because a
particularly good composite can be obtained, it is preferable to
use an ethylene-acrylic acid ester-maleic anhydride ternary
copolymer, and a specific example of this ethylene-acrylic acid
ester-maleic anhydride ternary copolymer is Bondine, made by
Arkema.
[0051] Examples of this glycidyl methacrylate-modified ethylenic
copolymer include glycidyl methacrylate-graft modified ethylene
polymers and glycidyl methacrylate-ethylene copolymers, of which a
glycidyl methacrylate-ethylene copolymer is preferable because a
particularly favorable composite can be obtained. A specific
example of said glycidyl methacrylate-ethylene copolymer is
Bondfast (made by Sumitomo Chemical). Examples of said glycidyl
ether-modified ethylene copolymers include glycidyl ether-graft
modified ethylene copolymers and glycidyl ether-ethylene
copolymers. A specific example of said ethylene alkyl acrylate
copolymers is Lotryl (made by Arkema).
[0052] Filler
[0053] A filler may be added to the cured epoxy resin. This filler
will be discussed in greater detail. It is preferable to use an
epoxy adhesive composition containing a filler in an amount of 0 to
100 weight parts (no more than 100 weight parts), and preferably 10
to 60 weight parts, per 100 weight parts of the combined resin
component including the elastomer component. Even more preferably,
the total amount of added filler is no more than 50 weight parts
per 100 weight parts of the combined resin component. Examples of
fillers that are used include reinforcing fibers such as carbon
fiber, glass fiber, and aramid fiber, while examples of powdered
fillers include calcium carbonate, mica, glass flakes, glass
balloons, magnesium carbonate, silica, talc, clay, carbon fiber,
and aramid fiber that has been pulverized.
[0054] Adjustment of Epoxy Adhesive
[0055] Next, the specific work of adjusting the epoxy adhesive will
be discussed. The epoxy resin main material, the curing agent, the
elastomer, and the filler are thoroughly mixed, and a small amount
of an epoxy adhesive solvent (a commonly known, commercially
available product) is added and mixed depending on the viscosity,
to obtain an adhesive composition (uncured epoxy adhesive). This
adhesive composition is applied to the necessary places on the
metal alloy part obtained in the step described above. How this is
applied does not matter, and may be brushing on by hand, or
application by coating machine that automatically applies the
adhesive.
[0056] Treatment Step after Epoxy Resin Adhesive Application
[0057] After coating, the coated product is placed in a vacuum
vessel or a pressure vessel, the pressure is reduced to close to a
vacuum, and after leaving the product for a few minutes, air is let
in to return the vessel to normal pressure (atmospheric pressure),
or preferably the product is left under a pressure environment of
several atmospheres or several dozen atmospheres. The pressure
reduction and elevation cycle is preferably repeated under this
pressure environment. This makes it easier for air or gas to escape
between the coating material and the metal alloy, and helps the
coating material to penetrate into the ultrafine texturing.
[0058] In actual mass production, using a pressure vessel and using
high-pressure air lead to higher cost both in terms of equipment
and expense, so a method in which the step of reducing pressure and
returning to normal pressure using the vacuum vessel is carried out
one time, or repeated a number of times, is an economical. With the
metal alloy of the present invention, sufficiently stable bonding
strength can be obtained in a few cycles of reduced pressure and
normal pressure. After being taken out of the vessel, the product
is preferably left at normal temperature, or under an environment
of about 40.degree. C., for about 30 minutes or longer.
Specifically, doing this allows a considerable portion of the
solvent to be volatilized even if a certain amount of solvent is
added to the epoxy adhesive composition.
[0059] FRP Prepreg
[0060] A commercially available FRP prepreg or CFRP prepreg can be
used. As commercially available products, those in which a carbon
fiber weave is impregnated with the above-mentioned epoxy resin
composition, those in which a film is first made from the
above-mentioned uncured epoxy resin, and then superposed with a
fiber weave, and so forth are sold as prepregs. The epoxy resin in
the prepreg that is used is mostly a dicyandiamide or amine curing
type, which maintain a B stage at normal temperature (in an uncured
state, but close to a solid), first melt in the process of being
heated to a hundred and some few dozen degrees centigrade, and then
solidify.
[0061] A CFRP prepreg will be discussed. It is cut to the required
shape and superposed in the required form to prepare a prepreg
portion. Specifically, when a plurality of sheets of a
unidirectional prepreg (a prepreg made from a weave in which there
are many warp threads and very few weft threads) are superposed,
the directions thereof are superposed, or superposed at an angle,
so that the directionality of strength of the final CFRP sheeting
can be controlled (designed), and there is said to be a great deal
of knowledge about how these are put together. Also, with a regular
weave of carbon fiber, the number of warp and weft threads is the
same, and it is said that if the prepregs are superposed by
offsetting the angle 45 degrees each time, strength that is equal
in all directions can be produced. In other words, the required
number of sheets and how they are superposed is designed ahead of
time, each prepreg is cut according to this, and the pieces are put
together as designed to complete the preparation.
[0062] Prepreg Lamination, and Method for Manufacturing
Composite
[0063] The above-mentioned FRP prepreg is placed on the
above-mentioned metal alloy part that has been coated with an epoxy
adhesive composition. When heated in this state, the epoxy resin
adhesive and the epoxy resin in the prepreg first melt and then are
cured. To join (bond) the two firmly together, they must be heated
while being pressed together, and any air contained in the gap must
be purged when the epoxy resins are melted. For example, a seat is
made in advance in the opposite shape of the face of the metal
alloy to be jointed, a polyethylene film is laid over this, the
above-mentioned metal alloy part is put in place, the prepreg is
placed on this, another polyethylene film is laid over the prepreg,
a fixing member (jig) in the final prepreg shape that has been
produced separately from a structural material or the like is
placed on this, and a weight is placed on top of this, thereby
pressing the components together and fixing them during heating and
curing. In other words, a jig and a weight are used for joining. Of
course, what matters is that the two pieces between pressed
together and cured, so various other methods can also be used, such
as fixing with screws, rather than using a weight and relying
solely on gravity.
[0064] Heating is performed by putting the metal alloy part, the
FRP prepreg, and the jig all together into a hot air dryer, an
autoclave, or another such heating furnace. This heating preferably
involves first leaving the pieces for several tens of minutes,
usually at 100 to 140.degree. C., to melt the adhesive component
and create a gel, then heating for another several tens of minutes
with the temperature raised to between 150 and 180.degree. C. for
curing. The ideal temperature conditions will vary with the type
and amount of the epoxy component, the curing agent component, and
so forth. Once the specified heating is complete, the product is
allowed to cool, the jig is removed, and the molded article is
taken out. If the above-mentioned polyethylene films were used for
release, they are peeled off.
[0065] Example of how Composite is Used
[0066] FIG. 1(a) is a diagram illustrating an example of using the
copper alloy part of the present invention in a seaplane pontoon,
and FIG. 1(b) is a cross section of the pontoon when cut along the
b-b line in FIG. 1(a). The pontoon 20 is one used for a small
seaplane or the like. The pontoon 20 is known to be resistant to
the growth of seaweed when left immersed for an extended period in
seawater or fresh water. To this end, the outer surface of the
pontoon 20 is covered with copper alloy sheeting 21. Lightweight
and strong CFRP 22 is bonded on the inside of the copper alloy
sheeting 21. Furthermore, the above-mentioned epoxy adhesive 23 is
securely bonded at the boundary layer of the CFRP 22 and the copper
alloy sheeting 21, which prevents the two from coming apart. Since
seaweed will not adhere, the pontoon 20 is maintenance-free. Since
this need to reduce the growth of seaweed is also present with the
hulls of boats and so forth, the copper alloy composite of the
present invention can also be used for the hulls of small
boats.
[0067] As detailed above, the copper alloy composite of the present
invention comprises a tightly integrated copper alloy part and FRP,
and makes it possible to provide parts and structures that
lightweight, have excellent properties such as electrical and
thermal conductivity and seaweed resistance in seawater and fresh
water, and furthermore have high mechanical strength. Industrial
fields in which the copper alloy composite of the present invention
can be utilized include parts used in mobile electronic devices,
automotive parts, boat parts, aircraft parts, moving robot parts,
and other such moving machinery parts, and structures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0068] FIG. 1(a) is a diagram illustrating an example of using the
composite of the present invention in a seaplane pontoon, and FIG.
1(b) is a cross section along the b-b line in FIG. 1(a);
[0069] FIG. 2 is a diagram of a copper alloy piece and CFRP that
have been integrated, and shows a test piece used to measure the
joint strength between a copper alloy and an FRP member as the
shear breaking strength;
[0070] FIG. 3 is a cross section of a baking jig used for bonding a
copper alloy piece and an FRP;
[0071] FIG. 4 is a diagram of a test piece used in a tensile
breaking test of a copper alloy piece produced by baking a copper
alloy piece and a CFRP;
[0072] FIG. 5 consists of 10,000 and 100,000 power electron
micrographs of a C1100 copper alloy piece that has been chemically
etched and subjected to a surface hardening treatment;
[0073] FIG. 6 consists of 10,000 and 100,000 power electron
micrographs of a C1020 copper alloy piece that has been chemically
etched and subjected to a surface hardening treatment;
[0074] FIG. 7 consists of 10,000 and 100,000 power electron
micrographs of a test piece obtained by chemically etching an
iron-based copper alloy ("KFC" made by Kobe Steel) piece and
subjecting it to a surface hardening treatment;
[0075] FIG. 8 consists of 10,000 and 100,000 power electron
micrographs of a test piece obtained by chemically etching a JIS
phosphor bronze type 2 (C5191) copper alloy piece and subjecting it
to a surface hardening treatment;
[0076] FIG. 9 is a roughness graph produced by scanning probe
microscope of a test piece obtained by chemically etching a pure
copper-based copper alloy C1100 (tough pitch copper) piece and
subjecting it to a surface hardening treatment;
[0077] FIG. 10 is a roughness graph produced by scanning probe
microscope of a test piece obtained by chemically etching a pure
copper-based copper alloy C1020 (oxygen-free copper) piece and
subjecting it to a surface hardening treatment; and
[0078] FIG. 11 is a roughness graph produced by scanning probe
microscope of a test piece obtained by chemically etching an
iron-containing copper alloy ("KFC" made by Kobe Steel) piece and
subjecting it to a surface hardening treatment.
BEST MODE FOR CARRYING OUT THE INVENTION
Experiment Equipment Used
[0079] Specific examples will now be given through working
examples, and the following equipment was used for measurement and
so forth.
[0080] (a) X-ray Surface Observation (XPS Observation)
[0081] An ESCA "AXIS-Nova" (made by Kratos/Shimadzu) was used, of
the type that looks at a surface a few microns in diameter and to a
depth of 1 to 2 nm, and the constituent elements in this
portion.
[0082] (b) Electron Beam Surface Observation (EPMA Observation)
[0083] An electron beam microanalyzer ("EPMA 1600" made by
Shimadzu) was used, of the type that looks at a surface a few
microns in diameter and to a depth of a few microns, and the
constituent elements in this portion.
[0084] (c) Electron Microscope Observation
[0085] Using a SEM type of electron microscope ("JSM-6700F" made by
JEOL), observations were made at 1 to 2 kV.
[0086] (d) Scanning Probe Microscope Observation
[0087] An "SPM-9600" (made by Shimadzu) was used.
[0088] (e) Measurement of Composite Joint Strength
[0089] Using a tensile tester ("Model 1323" made by Aiko
Engineering), the shear breaking strength was measured at a pulling
rate of 10 mm/minute.
Experiment Example 1
Copper Alloy and Adhesive
[0090] A commercially available C1100 tough pitch copper sheeting
with a thickness of 1 mm was purchased and cut into a rectangular
copper alloy piece 25 measuring 45 mm.times.18 mm (see FIG. 2). An
aqueous solution containing a commercially available aluminum alloy
degreaser ("NE-6" made by Meltex) in an amount of 7.5% was adjusted
to 60.degree. C. and used as a degreaser aqueous solution, and an
immersion tank was filled with it. The rectangular copper alloy
piece 25 was soaked for 5 minutes in this to degrease it, and then
was rinsed thoroughly with water. The copper alloy piece 25 was
then soaked for 1 minute in a 1.5% caustic soda aqueous solution
adjusted to 40.degree. C. in a separate tank, and rinsed with water
to perform preliminary base washing. Next, an aqueous solution
containing a copper alloy etchant ("CB5002" made by MEC) in an
amount of 20% and 30% hydrogen peroxide in an amount of 20% was
prepared as an etching solution, and the copper alloy piece 25 that
had undergone the above treatment was soaked for 10 minutes in this
etching solution adjusted to 25.degree. C., after which it was
rinsed with water.
[0091] Next, in a separate tank, an aqueous solution containing
caustic soda in an amount of 10% and sodium chlorite in an amount
of 5% was prepared as an oxidation aqueous solution, this was
adjusted to 65.degree. C., and then the above-mentioned copper
alloy piece 25 was soaked for 1 minute therein and rinsed
thoroughly with water. The piece was then soaked for another minute
in the previous etching aqueous solution, after which it was rinsed
with water, and again soaked for 1 minute in the oxidation aqueous
solution and rinsed with water. This product was dried for 15
minutes in a 90.degree. C. hot air dryer. The dried copper alloy
piece 25 was a dark reddish-brown in color. The copper alloy pieces
25 were wrapped in aluminum foil, then put in a plastic bag,
sealed, and stored. For the sake of reference, the oxidation
treatment was continued for 5 minutes on one piece, which turned
completely black. This made it clear that the dark-colored
component produced on the surface layer was cupric oxide.
[0092] Four days later, one of the pieces was measured for
roughness using a scanning probe microscope, which revealed that
the peak-valley mean spacing (RSm) referred to in JIS was 3.6
.mu.m, and the maximum roughness height (Rz) was 3.5 .mu.m. FIG. 9
shows the results of measuring this surface roughness with a
tester. The actual roughness measurement curve, as shown in FIG. 9,
is gentle, in which the fine peak-valley height difference is not
even 0.1 .mu.m, whereas the surface shape was such that large
valleys were present at a period of 5 to 10 .mu.m. These large
crevices looked like traces of the crystal grain boundary. It can
be predicted from the data in FIG. 9 that the true RSm is a number
between 6 and 10 .mu.m, and the RSm value obtained by scanning
analysis with this scanning microscope (mean length of roughness
curve) does not express the real situation. In analysis by scanning
probe microscope (performed by the attached computer), it was clear
that the small period of height difference of less than 0.1 .mu.m
was not well employed in the analysis of this data.
[0093] Meanwhile, the maximum roughness height Rz indicated the
correct measured value. Consequently, when measurements were made
again with a conventional roughness gauge, the RSm measured at a
length of 500 .mu.m came out as 8.1 .mu.m. In the end, the
roughness of the surface is determined by the sharpness of the
measurement end and the data processing method, so if the data is
judged to be abnormal, the only thing to do is make a decision from
the data and a micrograph taken by electron microscope.
Specifically, when the same object is observed by electron
microscope at 10,000 and 100,000 power, a relatively gentle hill
shape in which there are numerous openings (depressions) is
observed. These openings are such that the diameter of the circle,
or the average of the major and minor diameters of an ellipse, is
20 to 150 nm, and the period at which these openings are present is
100 to 300 nm. These openings correspond to fine texturing, and a
single hill made by this fine textured surface seems to correspond
to a single crystal grain as seen with a probe microscope. FIG. 5
is a photograph of this.
[0094] The same day the copper alloy piece 25 was taken out, it was
thinly coated at the end with a commercially available
liquid-liquid amine curing type of epoxy adhesive ("EP-106" made by
Cemedine). The piece was placed in a desiccator with the coated
side up, the pressure was reduced to 3 mmHg with a vacuum pump, and
after standing for 1 minute, air was let in to return to normal
pressure. The cycle of reduced pressure and returning to normal
pressure was repeated three times, and the piece was taken out of
the desiccator. The two ends coated with the adhesive 26 were put
together, and two copper alloy pieces were obtained as shown in
FIG. 2. The joined surface area (1.times.m) at the two ends of the
alloy pieces 25 was about 0.5 cm.sup.2. These pieces were put in a
hot air dryer adjusted to 120.degree. C. and heated with a 300 g
weight placed on the two overlapped copper alloy pieces. After 40
minutes of this heating, the temperature setting of the hot air
dryer was changed to 150.degree. C., and after the temperature had
risen to 150.degree. C., the pieces were left for 20 minutes, then
the hot air dryer was switched off and the door was left open while
the pieces cooled. The product had the shape shown in FIG. 2. Two
days later a tensile breaking test was conducted, in which the
shear breaking strength as an average of 4 sets was 36 MPa, which
means the bond was extremely strong.
Experiment Example 2
Copper Alloy and Adhesive
[0095] The etching aqueous solution was changed to 98% sulfuric
acid in an amount of 5%, aqueous hydrogen peroxide with a
concentration of 30% in an amount of 20%, and deionized water in an
amount of 75%, but everything else was exactly the same as in
Experiment Example 1. The adhesive bonding was also carried out in
an exactly the same manner as in Experiment Example 1, and the
shear breaking strength as an average of 4 sets was 34 MPa.
Experiment Example 3
Copper Alloy and Adhesive
[0096] A commercially available C1020 oxygen-free copper sheeting
with a thickness of 1 mm was used and cut to the same size as in
Experiment Example 1. An aqueous solution containing a commercially
available aluminum alloy degreaser ("NE-6" made by Meltex) in an
amount of 7.5% was adjusted to 60.degree. C. and used as a
degreaser aqueous solution. The copper alloy piece 25 was soaked
for 5 minutes in this to degrease it, and then was rinsed
thoroughly with water. The copper alloy piece 25 was then soaked
for 1 minute in a 1.5% caustic soda aqueous solution adjusted to
25.degree. C. in a separate tank, and rinsed with water to perform
preliminary base washing. Next, an aqueous solution containing a
copper alloy etchant ("CB5002" made by MEC) in an amount of 20% and
30% hydrogen peroxide in an amount of 20% was prepared as an
etching solution, and the copper alloy piece 25 that had undergone
the above treatment was soaked for 15 minutes and then rinsed with
water. Next, an aqueous solution containing caustic soda in an
amount of 10% and sodium chlorite in an amount of 5% was prepared
as an oxidation aqueous solution in a separate tank, this was
adjusted to 65.degree. C., and then the above-mentioned alloy
sheeting was soaked for 1 minute therein and rinsed thoroughly with
water.
[0097] The piece was then soaked for another minute in the previous
etching aqueous solution, after which it was rinsed with water, and
again soaked for 1 minute in the oxidation aqueous solution and
rinsed with water. This product was dried for 15 minutes in a
90.degree. C. hot air dryer. The dried copper alloy piece 25 was a
dark reddish-brown in color. The copper alloy pieces 25 were
wrapped in aluminum foil, then put in a plastic bag, sealed, and
stored. FIG. 6 shows the results of electron microscope
observation. As is clear from the 100,000 power micrograph, unlike
the micrograph in FIG. 5, the convex parts were more noticeable
than the concave parts, and there was an ultrafine texturing shape
in which granules with a diameter of 10 to 200 nm were mixed
together and present over the entire surface.
[0098] Also, the numerical value related to roughness measured with
a scanning probe microscope, that is, the peak-valley mean spacing
(RSm) referred to in JIS, was 1.0 .mu.m, and the maximum roughness
height (Rz) was 0.38 .mu.m. These numbers, however, did not express
the true state, just as in Experiment Example 1. Specifically, the
roughness curve obtained by probe microscope is shown in FIG. 10,
in which the value of Rz indicates the depth formed by large,
gentle valleys with a period of about 10 .mu.m as shown, while the
peak-valley mean spacing RSm can be seen to be a vague number that
also picks up the fine period. If a period demarcated by large,
gentle valleys is found from FIG. 10, it will be 7 to 13 .mu.m.
When measurements were made again with a conventional roughness
gauge, RSm was calculated to be 10 .mu.m, and Rz was 0.4 .mu.m.
[0099] After this, in exactly the same manner as in Experiment
Example 1, the ends was thinly coated with a commercially available
liquid-liquid amine curing type of epoxy adhesive ("EP-106" made by
Cemedine), the piece was placed in a desiccator and subjected to
the same treatment, two sides coated with the adhesive were put
together, and the coating was cured in a hot air dryer. A tensile
breaking test was conducted two days layer, in which the shear
breaking strength as an average of 4 sets was 36 MPa, which means
the bond was extremely strong.
Experiment Example 4
Copper Alloy and Adhesive
[0100] A commercially available iron-based copper alloy sheeting
with a thickness of 0.7 mm ("KFC" made by Kobe Steel) was purchased
and cut into numerous rectangular pieces measuring 45 mm.times.18
mm. An aqueous solution containing a commercially available
aluminum alloy degreaser ("NE-6" made by Meltex) in an amount of
7.5% was adjusted to 60.degree. C. and used as a degreaser aqueous
solution. The copper alloy piece 25 was soaked for 5 minutes in
this to degrease it, and then was rinsed thoroughly with water. The
copper alloy piece 25 was then soaked for 8 minutes in an aqueous
solution containing a copper alloy etchant ("CB5002" made by MEC)
in an amount of 20% and 30% hydrogen peroxide in an amount of 18%
in a separate tank, and then rinsed with water.
[0101] Next, an aqueous solution containing caustic soda in an
amount of 10% and sodium chlorite in an amount of 5% was prepared
as an oxidation aqueous solution in a separate tank, this was
adjusted to 65.degree. C., and then the above-mentioned alloy
sheeting was soaked for 1 minute therein and rinsed thoroughly with
water. The piece was then soaked for another minute in the previous
etching aqueous solution, after which it was rinsed with water, and
again soaked for 1 minute in the oxidation aqueous solution and
rinsed thoroughly with water. This product was dried for 15 minutes
in a 90.degree. C. hot air dryer. The dried copper alloy piece was
a dark reddish-brown in color. The copper alloy pieces were wrapped
in aluminum foil, then put in a plastic bag, sealed, and
stored.
[0102] After four days of this storage, one of the pieces was put
under a scanning probe microscope. The result is shown in FIG. 11.
The peak-valley mean spacing (RSm) referred to in JIS was 1.5
.mu.m, and the maximum roughness height (Rz) was 0.32 .mu.m.
Observation by 100,000 power electron microscope revealed that the
entire surface was covered by ultrafine texturing in which granules
with a diameter of 10 to 20 nm and large amorphous polygons with a
diameter of 50 to 150 nm were mixed together and in a stacked
shape, similar in form to the gullies on the slope of a lava
plateau. FIG. 7 is a micrograph of this.
[0103] The same day the copper alloy piece was taken out, it was
thinly coated at the end with a commercially available
liquid-liquid amine curing type of epoxy adhesive ("EP-106" made by
Cemedine). The piece was placed in a desiccator with the coated
side up, the pressure was reduced to 3 mmHg with a vacuum pump, and
after standing for 1 minute, air was let in to return to normal
pressure. The cycle of reduced pressure and returning to normal
pressure was repeated three times, and the piece was taken out of
the desiccator. The two ends coated with the adhesive were put
together, and the joined surface area was about 0.5 cm.sup.2. These
pieces were put in a hot air dryer adjusted to 120.degree. C. and
heated with a 300 g weight placed on the two overlapped copper
alloy pieces. After 40 minutes of heating at 120.degree. C., the
temperature setting of the hot air dryer was changed to 150.degree.
C., and after the temperature had risen to 150.degree. C., the
pieces were left for 20 minutes, then the hot air dryer was
switched off and the door was left open while the pieces cooled.
Two days later a tensile breaking test was conducted, in which the
shear breaking strength as an average of 4 sets was 40.5 MPa, which
means the bond was extremely strong.
Experiment Example 5
Copper Alloy and Adhesive
[0104] A commercially available JIS phosphor bronze type 2 (C5191)
sheeting with a thickness of 1 mm was purchased and cut into
numerous rectangular pieces measuring 45.times.18 mm. An aqueous
solution containing a commercially available aluminum alloy
degreaser ("NE-6" made by Meltex) in an amount of 7.5% was adjusted
to 60.degree. C. in a tank and used as a degreaser aqueous
solution. The above-mentioned copper alloy piece was soaked for 5
minutes in this to degrease it, and then was rinsed thoroughly with
water. The copper alloy piece was then soaked for 15 minutes in an
aqueous solution adjusted to 25.degree. C. and containing a copper
alloy etchant ("CB5002" made by MEC) in an amount of 20% and 30%
hydrogen peroxide in an amount of 18% in a separate tank, and then
rinsed with water. Next, an aqueous solution containing caustic
soda in an amount of 10% and sodium chlorite in an amount of 5% was
prepared as an oxidation aqueous solution in a separate tank, this
was adjusted to 65.degree. C., and then the above-mentioned alloy
sheeting was soaked for 1 minute therein and rinsed thoroughly with
water.
[0105] The piece was then soaked for another minute in the previous
etching aqueous solution, after which it was rinsed with water, and
again soaked for 1 minute in the oxidation aqueous solution and
rinsed thoroughly with water. This product was dried for 15 minutes
in a 90.degree. C. hot air dryer. The dried copper alloy piece was
a dark reddish-brown in color. The copper alloy pieces were wrapped
in aluminum foil, then put in a plastic bag, sealed, and stored.
Four days later, observation by electron microscope revealed that
substantially the entire surface was covered with ultrafine
texturing in which granules or amorphous polygons with a diameter
of 10 to 150 nm that are lined up and partially melted together in
a stacked shape. FIG. 8 is a micrograph of this ultrafine
texturing. After this, the C5191 phosphor bronze pieces were bonded
together and subjected to a tensile breaking test in exactly the
same manner as in Experiment Example 4. The shear breaking strength
as an average of 4 sets was 46 MPa, which means the bond was
extremely strong.
Experiment Example 6
Copper Alloy and Adhesive
[0106] A commercially available connector-use copper alloy sheeting
with a thickness of 0.4 mm ("KLF5" made by Kobe Steel) was
purchased and cut into numerous rectangular pieces measuring 45
mm.times.18 mm. The liquid treatment method was exactly the same as
in Experiment Example 4. As seen from the results of electron
microscope observation, there was fine texturing in which convex
components with a diameter of 10 to 150 nm completely filled in the
surface, and the spacing between the convex components was noted to
be extremely short, about 10 nm. The experiment for adhesive
bonding was also conducted in the same manner as in Experiment
Example 4. The tensile breaking test was also conducted in the same
manner as in Experiment Example 4, and while it was only breaking
data that was difficult to theorize, whose starting point was
separation due to moment breakage, and the sheeting was thin, a
numerical value of 36 MPa was obtained.
Experiment Example 7
Copper Alloy and Adhesive
[0107] A commercially available large connector-use copper alloy
sheeting with a thickness of 0.8 mm ("CAC16" made by Kobe Steel)
was purchased and cut into numerous rectangular pieces measuring 45
mm.times.18 mm. The liquid treatment method was exactly the same as
in Experiment Example 4. As seen from the results of electron
microscope observation, there was fine texturing in which convex
components with a diameter of 10 to 100 nm completely filled in the
surface, and the spacing between the convex components was noted to
be extremely short, about 10 nm, but a special shape of partially
acute film form was also present. The above-mentioned ultrafine
texturing covered 99% of the surface, though. The adhesive bonding
experiment was the same as in Experiment Example 4. The tensile
breaking test was also conducted in the same manner as in
Experiment Example 4. The shear breaking strength was 43 MPa.
Experiment Example 8
Copper Alloy and Adhesive
[0108] A commercially available large connector-use copper alloy
sheeting with a thickness of 0.4 mm ("KLF194" made by Kobe Steel)
was purchased and cut into numerous rectangular pieces measuring 45
mm.times.18 mm. The liquid treatment method was exactly the same as
in Experiment Example 4. As seen from the results of electron
microscope observation, granules with a diameter of 10 to 100 nm
completely filled in the surface, with a spacing of about 10 nm,
but in a 10,000 powder electron micrograph, it can be seen that the
areas around the large granules are actually concave, so it could
be said that countless concave components of 10 to 100 nm in
diameter cover the surface. The adhesive bonding experiment was the
same as in Experiment Example 4. The tensile breaking test was also
conducted in the same manner as in Experiment Example 4, and while
it was only breaking data that was difficult to theorize, whose
starting point was separation due to moment breakage, and the
sheeting was thin, a numerical value of 32 MPa was obtained.
Experiment Example 9
Production of Prepreg
[0109] A prepreg is a molding intermediate material in the form of
a sheet in which a weave of carbon, glass, or the like is permeated
with a thermosetting resin, and when it is heated and cured, it
produces a light yet strong fiber-reinforced plastic (FRP). In
Experiment Example 9, a thermosetting resin composed of the
components shown in the following Table 1 was used to make this
prepreg.
TABLE-US-00001 TABLE 1 Thermosetting resin used for prepreg Amount
(weight parts) Resin components Epoxy brominated bisphenol A-type
solid epoxy 10.0 resin resin ("EPC-152" made by Dainippon Ink &
Chemicals) bisphenol A-type liquid epoxy resin ("EP- 13.9 828" made
by Yuka Shell Epoxy) bisphenol F-type liquid epoxy resin ("EPC-
24.8 830" made by Dainippon Ink & Chemicals) Elastomer weakly
crosslinkable carboxyl group- 8.0 terminated solid acrylonitrile
butadiene rubber ("DN-611" made by Nippon Zeon) thermoplastic
resin, hydroxyl group- 3.0 terminated polyether sulfone ("PES-100P"
made by Mitsui Toatsu Chemical) Curing Agent
tetraglycidyldiaminodiphenylmethane ("ELM-434" made by 15.0
Sumitomo Chemical) 4,4'-diaminodiphenylsulfone ("4,4'-DDS" made by
25.0 Sumitomo Chemical) BF.sub.3 monoethylamine complex ("BF3-MEA")
0.3 Total 100.0
[0110] The thermosetting resin components shown in Table 1 were
mixed with a roll at normal temperature and made into a sheet. The
thermosetting resin film thus obtained was placed in a prepreg
machine and pressed by a standard method from both sides of carbon
fiber ("T-300" made by Toray) aligned in a single direction as
reinforcing fiber, which gave a prepreg adjusted to a resin content
of 38%. The fiber basis weight was 190 g/m.sup.2.
Experiment Example 10
Adhesive Agent
[0111] A common, commercially available liquid-liquid dicyandiamide
curing type of epoxy adhesive ("EP-106" made by Cemedine) was
purchased. Meanwhile, an ethylene-acrylic acid ester-maleic
anhydride ternary copolymer ("Bondine TX8030" made by Arkema),
which is a polyolefin resin, was purchased and freeze-dried and
pulverized at the temperature of liquid nitrogen, which gave a
powder of 30 .mu.m pass. Also, glass fiber with an average fiber
diameter of 9 .mu.m and a fiber length of 3 mm ("RES03-TP91" made
by Nippon Sheet Glass) was purchased and lightly pulverized in a
mortar. 100 g of "EP-106" epoxy adhesive, 5 g of the
above-mentioned powdered polyolefin resin, and 10 g of the
above-mentioned glass fiber were put in a polyethylene beaker and
thoroughly stirred, allowed to stand for 1 hour, and then stirred
again to mix well. This was termed an epoxy adhesive composition.
The adhesive composition thus obtained was used in place of the
"EP-106," but everything else was conducted in exactly the same
manner as in Experiment Example 1. A tensile breaking test was
conducted two days after the adhesive was cured, and the shear
breaking strength as an average of 4 sets was 38 MPa.
Experiment Example 11
Adhesive Agent
[0112] A common, commercially available epoxy adhesive ("EP-106")
was purchased. Meanwhile, a glycidyl methacrylate-ethylene
copolymer ("Bondfast E" made by Sumitomo Chemical), which is a
polyolefin resin, was purchased and freeze-dried and pulverized at
the temperature of liquid nitrogen, which gave a powder of 30 .mu.m
pass. 100 g of "EP-106" epoxy adhesive, 5 g of the above-mentioned
powdered polyolefin resin, and 10 g of the "RES03-TP91" glass fiber
were put in a polyethylene beaker and thoroughly stirred, allowed
to stand for 1 hour, and then stirred again to mix well. This was
termed an epoxy adhesive composition. The adhesive composition thus
obtained was used in place of the "EP-106," but everything else was
conducted in exactly the same manner as in Experiment Example 1. A
tensile breaking test was conducted two days after the adhesive was
cured, and the shear breaking strength as an average of 4 sets was
36 MPa.
[0113] It is clear from looking at the results of this experiment
example and Experiment Examples 1 and 10 that the basic bonding
strength is determined by the shape and properties of the metal
surface. Specifically, the fact that the results in this example
were substantially the same as those in Experiment Examples 1 and
10 seems to indicate that the basic performance of the adhesive
itself is no different between this example and with "EP-106." In
fact, since the adhesive of this example contains an elastomer, and
the coefficient of linear expansion should be close to that of the
metal because of the filler admixture, it was anticipated, based on
conventional wisdom, that a good effect would be obtained after
undergoing vibration or after undergoing a high temperature. This
is common sense to researchers at the forefront of adhesive
chemistry.
Experiment Example 12
Production of Composite, and Evaluation Thereof
[0114] A C1100 copper alloy piece with a thickness of 1 mm was cut
into numerous rectangular pieces measuring 45 mm.times.15 mm.
Liquid treatment was performed in exactly the same manner as in
Experiment Example 1. Specifically, the piece was degreased with an
"NE-6" aluminum alloy degreaser aqueous solution, then subjected to
preliminary base washing with a caustic soda aqueous solution with
a concentration of 1.5%, and then etched with a copper etching
aqueous solution, oxidized with an aqueous solution containing
caustic soda and sodium chlorite, then soaked for 1 minute in the
copper etching solution, rinsed with water, and then re-oxidized by
being soaked for another minute in an oxidation aqueous solution.
This product was dried for 15 minutes in a 90.degree. C. hot air
dryer. After drying, the above-mentioned copper alloy sheets were
wrapped together in aluminum foil and stored.
[0115] The same day the copper alloy piece that had undergone the
above-mentioned treatment was taken out, it was thinly coated at
the end with a commercially available liquid-liquid dicyandiamide
curing type of epoxy adhesive ("EP-106" made by Cemedine). The
piece was placed in a desiccator with the coated side up, the
pressure was reduced to 3 mmHg with a vacuum pump, and after
standing for 1 minute, air was let in to return to normal pressure.
The cycle of reduced pressure and returning to normal pressure was
repeated three times, and the piece was taken out of the
desiccator.
[0116] Baking Jig 1
[0117] FIG. 3 is a cross section of a baking jig for baking to bond
a copper alloy sheet and an FRP. FIG. 4 is a diagram of an
integrated product 10 of a copper alloy piece 11 and a CFRP 12,
produced by baking the copper alloy sheet and the CFRP in this
baking jig 1. The baking jig 1 is used to fix the copper alloy
piece 11 and the prepreg 12 when they are being baked. A mold main
body 2 is open on the top side, and a rectangular mold depression 3
is formed. In the bottom of this is formed a mold through-hole 4,
which is a hole that goes all the way through.
[0118] A bottom plate protrusion 6 of a mold bottom plate 5 was
inserted into the mold through-hole 4. The bottom plate protrusion
6 stuck out from a mold bottom plate 7 of the mold main body 2. The
bottom of the mold main body 2 was placed over a mold seat 8. The
baking jig 1 was such that the copper alloy piece 10 produced by
joining the copper alloy piece 11 and the CFRP 12 as shown in FIG.
4 was baked and manufactured in a state in which the mold bottom
plate 5 had been inserted into the mold depression 3 of the mold
main body 2. In short, this copper alloy piece composite 10 was
manufactured by the following procedure. First, a releasing film 17
was spread out over the entire top face of the mold bottom plate 5.
The copper alloy piece 11 and a flat PTFE spacer 16 were placed
over the releasing film 17.
[0119] Three to five sheets of fabric of carbon fiber (T-300
(Toray)) 12 that had been cut to the required size and produced by
regular weaving were layered over the PTFE spacer 16 made of PTFE
(polytetrafluoroethylene resin) and over the end of the copper
alloy piece 11. The carbon fiber weave 12 was impregnated with
uncured epoxy adhesive (EP-106) by injecting a volume of
approximately 1 cc from an injector. This produced an uncured CFRP
prepreg.
[0120] After the layering of this prepreg 12, a releasing film 13
(a polyethylene film used for release) was further layered over the
copper alloy piece 11 and the prepreg 12. Over this were placed
PTFE blocks 14 and 15 that were made of PTFE and used as weights.
If needed, a weight (not shown) of a few hundred grams may also be
placed. In this state, everything was put into a baking oven and
the prepreg was cured and allowed to cool, after which the weight,
the seat 8, and so forth were removed, and the bottom end of the
bottom plate protrusion 6 was pressed against the floor, which
removed the releasing films 13 and 17 as well as the copper alloy
composite 10 (see FIG. 4) of the copper alloy piece 11 and the
CFRP. The PTFE spacer 16 and the releasing films 17 and 13 can be
easily peeled away from the CFRP, because they are made of
non-stick material.
[0121] Further, the prepreg 12 and the copper alloy piece 11 were
inserted into place inside the baking jig 1 by the procedure
discussed above, the PTFE blocks 14 and 15 were placed over these,
and everything was put in a hot air dryer. Here, iron weights of
0.5 kg each were placed on the PTFE blocks 14 and 15, power was
turned on to the hot air dryer (baking oven), and the temperature
was raised to 135.degree. C. Heating was performed at 135.degree.
C. for 40 minutes, then the temperature was raised to 165.degree.
C. over a period of 5 minutes, held for 20 minutes at 165.degree.
C., and then the power was shut off and the contents were allowed
to cool with the door left shut. The product was taken out of the
hot air dryer the next day, the copper alloy composite 10 was
released from the baking jig 1, and the releasing polyethylene film
was peeled away to obtain an object in the shape shown in FIG. 4.
The same operation was repeated to obtain eight integrated
products.
[0122] Two days after the joining of the copper alloy composite 10,
four of the pieces were subjected to a tensile breaking test to
measure the shear strength of the joined portion of the copper
alloy piece 11 and the CFRP 12. The CFRP portion was sandwiched
between two pieces of SUS 304 stainless steel with a thickness of 1
mm and that had been sanded with sandpaper, and this was clamped in
a chuck. The shear breaking strength of the four sets on average
was 38 MPa, which was extremely strong. As shown in FIG. 2, the
joint surface area was calculated as 1.times.m. Next, the remaining
four pieces were clamped in a tensile tester in the same manner as
above, the pulling was halted at the point when approximately 20
MPa had been reached, the pieces were left for 10 minutes like
this, and then the chuck was loosened and the pieces removed from
the tester and allowed to rest. The next day, when these pieces
were subjected to a tensile breaking test, the result was 40 MPa on
average, with no particular decrease in joint strength being
noted.
Experiment Example 13
Production of Composite, and Evaluation Thereof
[0123] A C1100 copper alloy piece with a thickness of 1 mm was cut
into rectangular pieces measuring 45 mm.times.15 mm just as in
Experiment Example 12, and the same adhesive strength measurement
test pieces were produced. Specifically, the copper alloy piece 11
was coated with an adhesive agent and put in a desiccator, the
cycle of reducing pressure with a vacuum pump and returning to
normal pressure, etc., was repeated three times, and a copper alloy
piece that had been coated with an adhesive was prepared. Next, the
baking mold 1 shown in FIG. 3 was prepared, and everything was
performed as in Experiment Example 12. However, the CFRP prepreg
was produced as in Experiment Example 9.
[0124] Specifically, just as in Experiment Example 9, five of the
prepregs that had been cut were layered inside the baking jig 1,
the releasing film 13 was placed over the copper alloy 11 and the
prepreg 12, after which the hold-down PTFE blocks 14 and 15 were
put in place, and everything was put into a hot air dryer. Here,
iron weights of 0.5 kg each were placed on the PTFE blocks 14 and
15, power was turned on to the dryer, and the temperature was
raised to 135.degree. C. Heating was performed at 135.degree. C.
for 60 minutes, then the temperature was raised to 165.degree. C.
over a period of 10 minutes, held for 40 minutes at 165.degree. C.,
and then the power was shut off and the contents were allowed to
cool with the door left shut. The product was taken out of the hot
air dryer the next day, the copper alloy composite 10 was released
from the baking jig 1, and the releasing polyethylene film was
peeled away to obtain an object in the shape shown in FIG. 4. A
tensile breaking test was performed on the second day after
joining. The CFRP portion was sandwiched between two pieces of SUS
304 stainless steel with a thickness of 1 mm and that had been
sanded with sandpaper, and this was clamped in a chuck. The shear
breaking strength of the four sets on average was 35 MPa, which was
extremely strong. As shown in FIG. 2, the joint surface area was
calculated as 1.times.m.
Experiment Example 14
Copper Alloy and Adhesive: Comparative Example
[0125] Just as in Experiment Example 1, C1100 tough pitch copper
sheeting was cut into a rectangular copper alloy piece 25 measuring
45 mm.times.18 mm (see FIG. 2). An aqueous solution containing a
commercially available aluminum alloy degreaser ("NE-6" made by
Meltex) in an amount of 7.5% was adjusted to 60.degree. C. and used
as a degreaser aqueous solution, and an immersion tank was filled
with it. The rectangular copper alloy piece 25 was soaked for 5
minutes in this to degrease it, and then was rinsed thoroughly with
water. The piece was then soaked for 1 minute in a 1.5% caustic
soda aqueous solution adjusted to 40.degree. C. in a separate tank,
and rinsed with water to perform preliminary base washing. Next, an
aqueous solution containing 98% sulfuric acid in an amount of 10%
and 30% hydrogen peroxide in an amount of 20% was prepared as an
etching solution. The temperature of this etching solution was
adjusted to 25.degree. C., and the copper alloy piece 25 treated by
the above method was soaked for 10 minutes and then rinsed with
water.
[0126] Next, an aqueous solution containing caustic soda in an
amount of 10% and sodium chlorite in an amount of 5% was prepared
as an oxidation aqueous solution in a separate treatment tank, this
was adjusted to 65.degree. C., and then the above-mentioned copper
alloy piece 25 was soaked for 1 minute therein and rinsed
thoroughly with water. Unlike in Experiment Example 1, re-etching
and re-oxidation were not performed after this, and the piece was
dried for 15 minutes in a 90.degree. C. hot air dryer. The dried
copper alloy piece 25 was a dark reddish-brown in color, and it
looked exactly the same as in Experiment Example 1. The copper
alloy pieces 25 were wrapped in aluminum foil, then put in a
plastic bag, sealed, and stored.
[0127] The day after the pieces were stored, one of them was
measured for roughness using a scanning probe microscope, which
revealed the mean length (RSm) of the roughness curve referred to
in JIS to be from 13 to 15 mm, and the maximum roughness height
(Rz) to be from 3 to 4 .mu.m, meaning that the period between the
convex and concave parts of the roughness was greater than in
Experiment Example 1. Next, electron microscope observation was
performed at 10,000 and 100,000 power, but it was exactly the same
as in FIG. 5, and the fine texturing was the same as in Experiment
Example 1. In other words, the roughness had a period that was too
large to be called micron-order roughness, but otherwise a product
substantially the same as in Experiment Example 1 could be
produced. Using this product, a bonding experiment was conducted
between metal alloys using EP106 in exactly the same manner as in
Experiment Example 1. This was subjected to tensile breakage and
the shear breaking strength was found; in a total of five sets,
there was some variance between 18 and 27 MPa, with the mean being
20 MPa. The strength was clearly weaker than in Experiment Example
1.
Experiment Example 15
Copper Alloy and Adhesive: Comparative Example
[0128] A commercially available C1100 tough pitch copper sheeting
with a thickness of 1 mm was purchased and the surface was lightly
polished with 1000 grit sandpaper. This was cut into a rectangular
copper alloy piece 25 measuring 45 mm.times.18 mm (see FIG. 2). An
aqueous solution containing a commercially available aluminum alloy
degreaser ("NE-6" made by Meltex) in an amount of 7.5% was adjusted
to 60.degree. C. and used as a degreaser aqueous solution in a
tank. The rectangular copper alloy piece 25 was soaked for 5
minutes in this to degrease it, and then was rinsed thoroughly with
water. The copper alloy piece 25 was then soaked for 1 minute in a
1.5% caustic soda aqueous solution adjusted to 40.degree. C. in a
separate tank, and rinsed with water to perform preliminary base
washing. Next, an aqueous solution containing 98% sulfuric acid in
an amount of 10% and 30% hydrogen peroxide in an amount of 5% was
prepared as an etching solution, and the above-mentioned copper
alloy piece 25 was soaked for 10 minutes in the above-mentioned
solution adjusted to 25.degree. C., and then rinsed with water.
[0129] Next, an aqueous solution containing caustic soda in an
amount of 10% and sodium chlorite in an amount of 5% was prepared
as an oxidation aqueous solution in a separate treatment tank, this
was adjusted to 65.degree. C., and then the above-mentioned copper
alloy piece 25 was soaked for 1 minute therein and rinsed
thoroughly with water. The piece was then soaked for another minute
in the previous etching aqueous solution, after which it was rinsed
with water, and again soaked for 1 minute in the oxidation aqueous
solution and rinsed with water. This product was dried for 15
minutes in a 90.degree. C. hot air dryer. The dried copper alloy
piece 25 was a dark reddish-brown in color. The copper alloy pieces
25 were wrapped in aluminum foil, then put in a plastic bag,
sealed, and stored.
[0130] After four days of this storage, one of the pieces was put
under a scanning probe microscope and its roughness was measured.
The average of six scans revealed that the peak-valley mean spacing
(RSm) referred to in JIS was 18 .mu.m, and the maximum roughness
height (Rz) was 8.5 .mu.m. Observation by electron microscope was
also performed, but the result was the same as in FIG. 5. With this
copper piece, the roughness period was large at greater than 10
.mu.m, and was away from the micron-order roughness that is ideal
with the present invention.
[0131] Using this product, a bonding experiment was conducted
between metal alloys using EP106 in exactly the same manner as in
Experiment Example 1. This was then subjected to tensile breakage
and the shear breaking strength was found; in a total of five sets,
there was variance between 15 and 25 MPa, with the mean being 21
MPa. The strength was clearly weaker than in Experiment Example
1.
* * * * *