U.S. patent application number 12/521149 was filed with the patent office on 2010-02-04 for composite of metal and resin and method for manufacturing the same.
This patent application is currently assigned to TAISEI PLAS CO., LTD.. Invention is credited to Naoki Andoh, Masanori Naritomi.
Application Number | 20100028602 12/521149 |
Document ID | / |
Family ID | 39588613 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100028602 |
Kind Code |
A1 |
Naritomi; Masanori ; et
al. |
February 4, 2010 |
COMPOSITE OF METAL AND RESIN AND METHOD FOR MANUFACTURING THE
SAME
Abstract
It is an object to manufacture a composite of a metal part and a
resin composition part, which is improved so as to securely join
and integrate stainless steel and a resin. A stainless steel part
whose surface has been suitably roughened by chemical etching or
the like can be used. An integrated product is obtained by
inserting a stainless steel piece 1 with its surface treated into a
cavity formed by a movable-side mold plate 2 and a fixed-side mold
plate 3 of a metallic mold for injection molding 10 and injecting a
specific resin. PBT, PPS or an aromatic polyamide resin can be used
as the main resin component of a resin composition 4 that is used.
High injection joining strength is obtained if the resin
composition contains, as an auxiliary component, PET and/or a
polyolefin resin in the case of PBT, a polyolefin resin in the case
of PPS and an aliphatic polyamide resin in the case of an aromatic
polyamide resin.
Inventors: |
Naritomi; Masanori; (Tokyo,
JP) ; Andoh; 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: |
39588613 |
Appl. No.: |
12/521149 |
Filed: |
December 28, 2007 |
PCT Filed: |
December 28, 2007 |
PCT NO: |
PCT/JP2007/075287 |
371 Date: |
June 25, 2009 |
Current U.S.
Class: |
428/147 ; 216/52;
264/238 |
Current CPC
Class: |
B29K 2705/00 20130101;
B32B 2262/0261 20130101; B32B 5/147 20130101; C23F 1/22 20130101;
B29K 2077/10 20130101; B32B 2307/704 20130101; B32B 27/38 20130101;
B32B 2605/00 20130101; Y10T 428/24405 20150115; B32B 2307/714
20130101; B29C 45/14 20130101; B29C 45/14311 20130101; B32B 27/32
20130101; C23C 22/18 20130101; B32B 27/18 20130101; B32B 2307/542
20130101; B32B 2457/00 20130101; C23C 22/83 20130101; B32B 27/36
20130101; B32B 15/08 20130101; B32B 2262/106 20130101; B32B
2262/101 20130101; C23C 22/57 20130101; B32B 2262/0269 20130101;
B29C 2045/14868 20130101; B29C 45/14336 20130101; B32B 27/34
20130101; B29K 2705/02 20130101; B32B 2509/00 20130101; B29K
2067/006 20130101; B32B 27/308 20130101; B32B 15/18 20130101; B32B
27/286 20130101; B32B 2535/00 20130101; B32B 2270/00 20130101; B32B
2307/54 20130101; C23C 22/05 20130101; B29K 2081/04 20130101 |
Class at
Publication: |
428/147 ;
264/238; 216/52 |
International
Class: |
B32B 3/00 20060101
B32B003/00; C23F 1/00 20060101 C23F001/00; B29C 45/00 20060101
B29C045/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2006 |
JP |
2006-354636 |
Claims
1. A composite of metal and resin, consisting of: a steel part made
of stainless steel, in which the surface is chemically etched after
being worked into a specific shape and substantially the entire
surface is covered with a ultrafine textured face in which
amorphous polygons or particulates with a diameter of 20 to 70 nm
are stacked on top of one another, and a resin part made of one
type of resin selected from the group consisting of a first resin
composition, whose main component is a polyphenylene sulfide resin,
a second resin composition whose main component is a polybutylene
terephthalate resin and a third resin composition whose main
component is an aromatic polyamide resin, which is directly joined
by injection molding onto the ultrafine textured face of said steel
part.
2. The composite of metal and resin according to claim 1, wherein
the resin component of said first resin composition is a resin
composition in which the polyphenylene sulfide resin is the main
component and a polyolefin resin is an auxiliary component.
3. The composite of metal and resin according to claim 1, wherein
the resin component of said second resin composition is a resin
composition in which the polybutylene terephthalate resin is the
main component and a polyethylene terephthalate resin and/or a
polyolefin resin is an auxiliary component.
4. The composite of metal and resin according to claim 1, wherein
the resin component of said third resin composition is a resin
composition, in which a mixture of different kinds of aromatic
polyamide resins is the main component, or a resin composition, in
which an aromatic polyamide resin is the main component and an
aliphatic polyamide resin is an auxiliary component.
5. The composite of metal and resin according to claim 2, wherein
said first resin composition contains the polyphenylene sulfide
resin by 70 to 97 wt % and the polyolefin resin by 3 to 30 wt
%.
6. The composite of metal and resin according to claim 3, wherein
said second resin composition contains the polybutylene
terephthalate resin by 70 to 97 wt % and the polyethylene
terephthalate resin and/or polyolefin resin by 3 to 30 wt %.
7. The composite of metal and resin according to claim 4, wherein
said third resin composition contains the aromatic polyamide resin
by 70 to 95 wt % and the aliphatic polyamide resin by 5 to 30 wt
%.
8. The composite of metal and resin according to any of claims 1 to
7, wherein at least one type of reinforcing fiber selected from
among glass fiber, carbon fiber, nylon fiber and aramid fiber, in
an amount of 20 to 60 wt %, and at least one type of filler
selected from among calcium carbonate, magnesium carbonate, silica,
talc, clay and glass powder are contained in said one type of resin
selected from the group consisting of said first resin composition,
said second resin composition and said third resin composition.
9. A method for manufacturing a composite of metal and resin,
comprising: a shaping step of shaping a substrate composed of
stainless steel by mechanical working; a liquid treatment step
including chemical etching for providing the surface of said shaped
substrate with a ultrafine textured face, in which protrusions with
a height, width and length of at least 10 nm rise up at a spacing
period of at least 10 nm, and for obtaining a surface roughness, in
which the mean width (RSm) of profile elements made up of said
ultrafine textured face is 0.5 to 10 .mu.m and the maximum height
of roughness (Rz) is 0.2 to 5 .mu.m; an insertion step of inserting
said substrate that has undergone the liquid treatment into a
metallic mold for injection molding; an injection step of injecting
onto the surface of said inserted substrate one type of resin; and
an integration step of integrating said substrate with said one
type of resin by said injection, said one type of resin being
selected from: a first resin composition in which a polyphenylene
sulfide resin is the main component and a polyolefin resin is an
auxiliary component, a second resin composition in which a
polybutylene terephthalate resin is the main component and a
polyethylene terephthalate resin and/or a polyolefin resin is an
auxiliary component, and a third resin composition that is a resin
composition in which a mixture of different kinds of aromatic
polyamide resins is the main component, or a resin composition in
which an aromatic polyamide resin is the main component and an
aliphatic polyamide resin is an auxiliary component.
10. A method for manufacturing a composite of metal and resin,
comprising: a shaping step of shaping a substrate composed of
stainless steel by mechanical working; a chemical etching step of
immersing the substrate that has undergone said shaping step in a
sulfuric acid aqueous solution to chemically etch the surface
thereof; an insertion step inserting the substrate that has
undergone said chemical etching into a metallic mold for injection
molding; an injection step of injecting onto the surface of said
inserted substrate one type of resin; and an integration step of
integrating said substrate with said one type of resin by said
injection, said one type of resin being selected from the group
consisting of: a first resin composition in which a polyphenylene
sulfide resin is the main component and a polyolefin resin is an
auxiliary component, a second resin composition in which a
polybutylene terephthalate resin is the main component and a
polyethylene terephthalate resin and/or a polyolefin resin is an
auxiliary component, and a third resin composition that is a resin
composition, in which a mixture of different kinds of aromatic
polyamide resins is the main component, or a resin composition, in
which an aromatic polyamide resin is the main component and an
aliphatic polyamide resin is an auxiliary component.
11. A method for manufacturing a composite of metal and resin,
comprising: a shaping step of shaping stainless steel by mechanical
working; a chemical etching step immersing the stainless steel
substrate that has undergone said shaping step in a sulfuric acid
aqueous solution to chemically etch the surface thereof; an
oxidation step of immersing the substrate that has undergone said
chemical etching step in a nitric acid aqueous solution; an
insertion step of inserting the substrate that has undergone said
oxidation step into a metallic mold for injection molding; an
injection step of injecting onto the surface of the inserted
substrate one type of resin; and an integration step of integrating
said substrate with said one type of resin by said injection, said
one type of resin being selected from the group consisting of: a
first resin composition in which a polyphenylene sulfide resin is
the main component and a polyolefin resin is an auxiliary
component, a second resin composition in which a polybutylene
terephthalate resin is the main component and a polyethylene
terephthalate resin and/or a polyolefin resin is an auxiliary
component, and a third resin composition that is a resin
composition, in which a mixture of different kinds of aromatic
polyamide resins is the main component, or a resin composition in
which an aromatic polyamide resin is the main component and an
aliphatic polyamide resin is an auxiliary component.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a composite of a metal
part, particularly one made of stainless steel or a part made of an
alloy thereof, and a molded resin article, which is used for the
housings of electronic equipments, the housings of consumer
electrical equipments, mechanical parts and so forth and also
related to a method for manufacturing the composite. More
particularly, the present invention relates to a composite, in
which a thermoplastic resin composition is integrated with a
stainless steel part made by mechanical working, and to a method
for manufacturing the composite and also relates to a composite of
metal and resin, which can be used in various electronic
equipments, consumer electrical products, medical instruments,
automotive structural parts, automotive mounted equipments or other
electrical parts or in corrosion resistant exterior trim parts or
the like and to a method for manufacturing the composite.
BACKGROUND OF THE INVENTION
[0002] Technology for integrating metals and resins is needed in
many different fields of industry, such as manufacturing of parts
for automobiles, consumer electrical products, industrial machinery
and so forth and many adhesive agents have been developed for this
purpose. Some very excellent adhesives have been proposed. For
example, adhesives that exhibit their function at normal
temperature or with heating are used to integrally join metals and
synthetic resins and this method is currently a common joining
technique.
[0003] On the other hand, more rational joining methods that do not
involve the use of an adhesive have been studied heretofore. 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
using any adhesive. For instance, the inventors proposed a method,
in which a molten resin is injected onto a metal part preliminarily
inserted into a metallic mold for injection molding thereby forming
a resin portion and at the same time the molded article and the
metal part are joined (hereinafter this will be referred to as
"injection joining").
[0004] According to the technology, a manufacturing technique was
proposed, in which a polybutylene terephthalate resin (hereinafter
referred to as "PBT") or a polyphenylene sulfide resin (hereinafter
referred to as "PPS") is joined by injection joining to an aluminum
alloy (see Japanese Patent Application Laid-open No. 2004-216425:
Patent Document 1, for example). A joining technique was also
disclosed, in which somewhat large holes (but invisible to the
naked eye) is made in an anodized film on a piece of aluminum and a
synthetic resin is made to penetrate into these holes and adjoined
there (see WO/2004-055248 A1: Patent Document 2, for example).
[0005] The principle behind the injection joining in Patent
Document 1 is as follows. An aluminum alloy is immersed in a dilute
aqueous solution of a water-soluble amine compound and the aluminum
alloy is finely etched with a weakly basic aqueous solution. It was
found that the amine compound molecules are adsorbed to the surface
of the aluminum alloy at the same time in this immersion treatment.
After undergoing this immersion treatment, the aluminum alloy is
inserted into a metallic mold for injection molding and a molten
thermoplastic resin is injected under high pressure.
[0006] Here, the amine compound molecules adsorbed to the surface
of the aluminum alloy encounter the thermoplastic resin to produce
a chemical reaction such as an exothermic reaction or a
macromolecular cleaving reaction. As a result of this chemical
reaction, the thermoplastic resin, which was apt to be quenched,
crystallized and solidified by contact with the aluminum alloy held
at a low temperature of the mold, is not solidified as quickly and
gets into ultrafine recesses on the aluminum alloy surface.
Consequently, with a composite composed of an aluminum alloy and a
thermoplastic resin, the thermoplastic resin is securely joined
(hereinafter also referred to as fixed) without being separated
from the aluminum alloy surface. That is, when an exothermic
reaction or a macromolecular cleaving reaction occurs, a strong
injection joint is produced. It has actually been confirmed that
PBT or PPS, which can undergo the above-mentioned chemical reaction
with an amine compound, can be joined by injection joining to an
aluminum alloy. Another well known technique involves performing
chemical etching preliminarily, then inserting a metal part into
the metallic mold of an injection molding machine and performing
injection molding with a thermoplastic resin material (see Japanese
Patent Application Laid-Open No. 2001-225352: Patent Document 3,
for example).
[0007] However, although the joining principle in Patent Document 1
by the inventors does exhibit an extremely good effect with
aluminum alloys or the like, it has not effect in injection joining
to other metals besides aluminum alloys. Accordingly, there has
been a need for the development of a novel technique for joining
metals and resins. The inventors discovered such a novel technique
in the course of making improvements to injection joining of a hard
resin to an aluminum alloy. Specifically, the conditions were
discovered under which injection joining might be possible without
any chemical adsorption of the amine compound to the metal part
surface, in other words, without the help of a special exothermic
reaction or any particular chemical reaction.
[0008] At least two conditions are necessary. The first condition
is that a hard resin of high crystallinity be used, namely, that
PPS, PBT or an aromatic polyamide be used and, furthermore, that
these be suited to injection joining to obtain a further improved
composition. Another condition is that the surface layer of the
metal part have a suitably rough shape and that the surface be
hard. In ordinary words, this means that the surface is strong and
strength is expressed in terms of material mechanics by tensile
strength, compression strength, shear strength and so forth.
However, the actual thickness of the surface layer to which
attention is paid in the present invention is from ten to a few
dozen nanometers and the strength of such a fine portion can be
rephrased as hardness. Therefore, the surface layer is preferably a
ceramic layer whose hardness is higher than that of metal crystals
and, more specifically, the inventors attained the conclusion that
it is essential for the surface layer to be a metal oxide or metal
phosphorus oxide.
[0009] For example, when a shaped material in which a copper alloy
serves as the substrate is used and it is immersed in an acidic
hydrogen peroxide aqueous solution, the copper is oxidized to
become copper ions. As a result, if the immersion conditions are
suitably set, the surface of the substrate is chemically etched to
a surface roughness in which the bumps have a period of one to
several microns. If the chemically etched copper alloy that has
been shaped is then immersed in a strongly basic sodium chlorite
aqueous solution, the copper is oxidized but the copper ions do not
dissolve and the surface is covered with a thin layer of cupric
oxide. Examination of this surface with an electron microscope
revealed it to be covered by a ultrafine textured face in which
recesses (openings) with a diameter of several dozen to several
hundred nanometers are present at a period of several hundred
nanometers.
[0010] These shaped copper alloys with their surfaces treated are
considered theoretically as follows, assuming that they are
inserted into a metallic mold for injection molding. The metallic
mold for injection molding and the inserted shaped copper alloy are
generally held at a temperature that is at least by 100.degree. C.
below the melting point of the resin being injected, although it
varies with the injection molding conditions, so there is a high
possibility that the temperature of injected resin may have dropped
below its melting point at the time when it is quenched upon
entering the channel inside the metallic mold for injection molding
and comes into contact with copper alloy part.
[0011] Regardless of the crystalline resin, when it is rapidly
cooled to below its melting point, it does not become crystallized
and solidified immediately (that is, in zero time) but there is a
time, albeit an extremely short time, for the resin to remain in a
molten state below the melting temperature or, in other words, in a
super-cooled state. If the roughness (surface roughness) of a
shaped alloy is on the micron order, that is, if the recesses are
large with an inside diameter of several microns, then
microcrystalline resin will penetrate into these recesses within
the limited time from super-cooled state to creation of the initial
crystals, that is, microcrystals. To put this in another way, if
the numerical density of the macromolecular microcrystal group that
is produced is still low, then the resin will sufficiently
penetrate into the recesses as long as the recesses are large with
an inside diameter of several microns.
[0012] These microcrystals of the injected resin are surmised from
molecular models to have a size from a few to more than a dozen
nanometers. If there are fine openings (holes in the recesses)
about 50 nm in diameter in the inner walls of the above-mentioned
micron-order recesses, then there is a slight possibility of
penetration, although it can hardly be said that microcrystals can
readily penetrate these fine openings. Specifically, countless
microcrystals are simultaneously produced, so there is an abrupt
increase in the viscosity of the resin flow at places abutting on
the metal face of the mold or at the distal end of the injected
resin. Therefore, this resin flow is surmised to have a shape
resembling the roots of a plant that stick slightly into the fine
openings in the inner wall faces.
[0013] In other words, the flowing molten resin cannot penetrate
into the deep portions of the fine openings but does penetrate
somewhat, then crystallizes and solidifies to become a crystalline
resin that has solidified in the micron-order recesses. In
addition, if the metal surface layer that forms the fine openings
is copper oxide, that is, a hard ceramic surface layer, then the
resin will be hooked more securely within the recesses, making it
less likely that the resin having solidified and crystallized will
come out of the recesses. In short, the joint strength will be
higher.
[0014] Improving the resin composition that is injected is an
important element in the present invention. Specifically, if the
resin composition is one that crystallizes slowly in injection
molding (when quenched from a molten state to a temperature below
the melting point), the joint strength will be higher. This is a
requirement for a resin composition to be suitable for injection
joining. Based on this, the inventors discovered that, if the
surface of a shaped copper alloy is chemically etched as discussed
above, the surface layer is made into a ceramic by a surface
treatment such as oxidation and a hard crystalline resin is joined
by injection joining to this, good joining ability is obtained
(PCT/JP2007/070205). The inventors have also made a proposal based
on their finding that, in addition to the above-mentioned PBT-based
and PPS-based resins, a resin composition whose main component is
an aromatic polyamide resin is also a suited to injection joining
as a resin composition which is hard and highly crystalline and
crystallizes extremely slowly during quenching similarly as in the
technology discussed just above (PCT/JP2006/324493).
[0015] In the above description about the theory of injection
joining, there is nothing that limits the kinds of metal. This
indicates that injection joining can be performed using PBT, PPS or
other such crystalline resin that has been improved for use in
injection joining with respect to all metals and metal alloys, as
long as it has the same surface shape and surface layer properties.
Patent Document 3 discloses a method for manufacturing a lead
wire-equipped battery cover having a shape such that several copper
wires pass through the middle portion of a PPS disk, in which a
chemically etched copper wire is inserted into a metallic mold for
injection molding, and PPS is injected. This technology is said to
be characterized by the fact that even if the internal pressure of
gas generated in a battery rises a labyrinth effect will prevent
the gas from leaking out through the lead wire part owing to the
shape of bumps (roughness) on the surface of a copper wire by
chemical etching.
[0016] At first glance the technology discussed in Patent Document
3 represents one that is similar to that according to the present
invention. However, it is not the above-mentioned injection joining
technology that the inventors assert in detail but is instead a
technology that is an extension of existing injection molding
technology and is no more than one that utilizes the difference in
the linear coefficient of expansion of metals and the molding
shrinkage of resins. In manufacturing a shaped article in which a
rod-like metal piece passes through the inner portion of a resin
part, if the resin is injected around this rod-like piece for
injection molding, then the molded article is parted from the mold
for injection molding and allowed to be cooled, the rod-like piece
is in such a situation as to be pressed by the surrounding molded
resin portion. The reason is that the linear coefficient of
expansion of a metal is at most 1.7 to 2.5.times.10.sup.-5.degree.
C..sup.-1 for an aluminum alloy, magnesium alloy, copper or copper
alloy and, even if the calculation is made on the assumption that
the metal has been removed from the metallic mold for injection
molding and cooled to room temperature, the shrinkage will be in a
range of the linear coefficient of expansion multiplied by a
hundred and several tens of degrees and it will be no more than 0.2
to 0.3% of the total length.
[0017] Concerned with a resin, however, the molding shrinkage is
about 1% for PPS and 0.5% for PPS containing glass fiber and even
for a resin, in which the filler content has been increased, the
resin portion will always undergo more heat shrinkage than the
metal part after injection molding. Therefore, if a shaped article
in which the metal part is disposed in the center and this metal
part goes through the resin portion is produced by injection
molding with an insert, an integrated product can be manufactured
in which the metal part is not likely to come loose due to the
pressing effect produced by heat shrinkage after the molding of the
resin portion.
[0018] This method for manufacturing an integrated metal and resin
product that makes use of heat shrinkage is known conventionally
and is used to fabricate knobs on fuel oil stoves, for example.
This method involves inserting a thick iron needle with a diameter
of about 2 mm into a metallic mold for injection molding and
injecting a heat resistant resin or the like into the mold. In this
method, jagged bumps (by knurling) are formed around the outer
peripheral face of the needle and the resin is injected and molded
so that there is no relative movement. Patent Document 3 discloses
that the surface configuration is smoothed by changing the
texturing process from a physical process to a chemical process
with knurling or the like, bumps are made finer and grip effect is
improved by using a resin that is hard and crystalline.
[0019] The composite according to the present invention does not at
all require that the resin press the metal by heat shrinkage or the
like, and even with a shaped article in which two flat plates are
joined together at their flat planes, a tremendous force is needed
to break the joint. In order that the joined state of the metal and
thermoplastic resin is to be maintained stably over an extended
period, it is actually necessary for the linear coefficients of
expansion of the two materials to be close in value. The linear
coefficient of expansion of a thermoplastic resin composition can
be lowered considerably by adding a large amount of glass fiber,
carbon fiber or other such reinforcing fiber (that is, a filler)
but the limit to this is generally 2 to 3.times.10.sup.-5.degree.
C..sup.-1. Kinds of metals that have such numerical value at a
normal temperature or so are aluminum, magnesium, copper and
silver.
[0020] The present invention relates to technology that makes
possible the injection joining of a hard resin to stainless steel.
The linear coefficient of expansion of stainless steel is about
1.times.10.sup.-5.degree. C..sup.-1, which corresponds to about the
middle value of the above-mentioned group of metals. In this sense,
research and development related to injection joining conducted by
the inventors lags behind in priority, while it is thought very
likely that it can be used if the temperature range in use is
narrow and the inventors have also conducted research and
development into stainless steel.
[0021] Stainless steel has a specific gravity of about 8. It has
high mechanical strength and is used as a metal with high corrosion
resistance. Therefore, stainless steel parts are frequently used in
various heavy-duty electronic and electrical equipments, medical
instruments, automotive mounted equipments, automobile parts,
marine machineries and other such parts used in movable equipments
and particularly in the casings and housings of equipments that may
be exposed to drops of salt water or sea water. If a hard resin can
be injected onto stainless steel, the production of these casings
or housings for equipments is considered to be extremely easy.
[0022] The required conditions for the injection joining of a metal
and a resin will once again be summed and explained below based on
the hypothesis of the inventors. Specifically, to obtain good
injection joining strength, at least the shaped metal should
satisfy the following conditions.
[0023] (1) The surface has large bumps (surface roughness) obtained
by chemical etching and the period thereof is usually on the micron
order, which in the present invention refers to the range of 0.5 to
10 .mu.m.
[0024] (2) The surface is sufficiently hard (a metal oxide or metal
phosphorus oxide) and, to prevent slippage, has a coarse surface
that consists of ultrafine bumps on the nanometer order (a coarse
surface in subjective view with an electron microscope).
[0025] (3) The resin must be a crystalline resin of high hardness,
while it is particularly favorable to use these improved
compositions in which the crystallization rate during quenching is
further slowed.
[0026] The findings of the inventors have shown that this
hypothesis is correct for magnesium alloys, copper alloys, and
titanium alloys. The "coarse surface" in (2) above is a figure of
speech expressing what is observed with an electron microscope and
high injection joining strength can be obtained when the surface is
a ultrafine textured surface in which the spacing period is at
least 10 nm and the height or depth was at least 10 nm.
SUMMARY OF THE INVENTION
[0027] The present invention was conceived in light of the
technical background discussed above and achieves the following
object.
[0028] It is an object of the present invention to provide a metal
and resin composite, in which a resin is joined by injection
joining to a piece of shaped stainless steel and a good joint
strength is obtained, as well as a method for manufacturing this
composite.
[0029] It is another object of the present invention to provide a
metal and resin composite, in which joinability is improved by
injection joining between a shaped stainless steel with surface
treatment performed and a high-hardness crystalline resin
composition, as well as a method for manufacturing this
composite.
[0030] The present invention employs the following means for
achieving the stated objects.
[0031] The composite of metal and resin according to the present
invention 1 consists of:
[0032] a steel part made of stainless steel, in which the surface
is chemically etched after being worked into a specific shape and
substantially the entire surface is covered with a ultrafine
textured face in which amorphous polygons or particulates with a
diameter of 20 to 70 nm are stacked on top of one another, and a
resin part made of one type of resin selected from the group
consisting of a first resin composition, whose main component is a
polyphenylene sulfide resin, a second resin composition whose main
component is a polybutylene terephthalate resin and a third resin
composition whose main component is an aromatic polyamide resin,
which is directly joined by injection molding onto the ultrafine
textured face of said steel part.
[0033] The method for manufacturing a composite of metal and resin
according to the present invention 9 comprises:
[0034] a shaping step of shaping a substrate composed of stainless
steel by mechanical working;
[0035] a liquid treatment step including chemical etching for
providing the surface of said shaped substrate with a ultrafine
textured face, in which protrusions with a height, width and length
of at least 10 nm rise up at a spacing period of at least 10 nm,
and for obtaining a surface roughness, in which the mean width
(RSm) of profile elements made up of said ultrafine textured face
is 0.5 to 10 .mu.m and the maximum height of roughness (Rz) is 0.2
to 5 .mu.m;
[0036] an insertion step of inserting said substrate that has
undergone the liquid treatment into a metallic mold for injection
molding;
[0037] an injection step of injecting onto the surface of said
inserted substrate one type of resin; and
[0038] an integration step of integrating said substrate with said
one type of resin by said injection,
[0039] said one type of resin being selected from: a first resin
composition in which a polyphenylene sulfide resin is the main
component and a polyolefin resin is an auxiliary component,
[0040] a second resin composition in which a polybutylene
terephthalate resin is the main component and a polyethylene
terephthalate resin and/or a polyolefin resin is an auxiliary
component, and
[0041] a third resin composition that is a resin composition in
which a mixture of different kinds of aromatic polyamide resins is
the main component, or a resin composition in which an aromatic
polyamide resin is the main component and an aliphatic polyamide
resin is an auxiliary component.
[0042] The method for manufacturing a composite of metal and resin
of present invention 10 comprises:
[0043] a shaping step of shaping a substrate composed of stainless
steel by mechanical working;
[0044] a chemical etching step of immersing the substrate that has
undergone said shaping step in a sulfuric acid aqueous solution to
chemically etch the surface thereof;
[0045] an insertion step inserting the substrate that has undergone
said chemical etching into a metallic mold for injection
molding;
[0046] an injection step of injecting onto the surface of said
inserted substrate one type of resin; and
[0047] an integration step of integrating said substrate with said
one type of resin by said injection,
[0048] said one type of resin being selected from the group
consisting of:
[0049] a first resin composition in which a polyphenylene sulfide
resin is the main component and a polyolefin resin is an auxiliary
component,
[0050] a second resin composition in which a polybutylene
terephthalate resin is the main component and a polyethylene
terephthalate resin and/or a polyolefin resin is an auxiliary
component, and
[0051] a third resin composition that is a resin composition, in
which a mixture of different kinds of aromatic polyamide resins is
the main component, or a resin composition, in which an aromatic
polyamide resin is the main component and an aliphatic polyamide
resin is an auxiliary component.
[0052] The method for manufacturing a composite of metal and resin
according to the present invention 11 comprises:
[0053] a shaping step of shaping stainless steel by mechanical
working;
[0054] a chemical etching step immersing the stainless steel
substrate that has undergone said shaping step in a sulfuric acid
aqueous solution to chemically etch the surface thereof;
[0055] an oxidation step of immersing the substrate that has
undergone said chemical etching step in a nitric acid aqueous
solution;
[0056] an insertion step of inserting the substrate that has
undergone said oxidation step into a metallic mold for injection
molding;
[0057] an injection step of injecting onto the surface of the
inserted substrate one type of resin; and
[0058] an integration step of integrating said substrate with said
one type of resin by said injection,
[0059] said one type of resin being selected from the group
consisting of:
[0060] a first resin composition in which a polyphenylene sulfide
resin is the main component and a polyolefin resin is an auxiliary
component,
[0061] a second resin composition in which a polybutylene
terephthalate resin is the main component and a polyethylene
terephthalate resin and/or a polyolefin resin is an auxiliary
component, and
[0062] a third resin composition that is a resin composition, in
which a mixture of different kinds of aromatic polyamide resins is
the main component, or a resin composition in which an aromatic
polyamide resin is the main component and an aliphatic polyamide
resin is an auxiliary component.
FIELD OF APPLICATION
[0063] Applying the present invention in various fields affords
better joinability (fixability), improvement of productivity,
higher efficiency, an extended range of application and so forth
and makes possible the rationalization of manufacture and the
enhancement of corrosion resistance in the casings of electronic
equipments and consumer electrical equipments. As a result, the
present invention can contribute to better productivity and
performance in casings and parts used in mobile electronic
equipments, mounted electrical and electronic equipments,
marine-use electrical and electronic equipments and many other
fields.
EFFECTIVENESS
[0064] As explained in detail above, with the composite and method
for manufacturing the composite according to the present invention,
a resin composition part and a stainless steel metal part are
integrated so that they may not readily come apart. A thermoplastic
resin composition having a resin component containing PBT by 70 to
97 wt % and PET and/or polyolefin resin by 3 to 30 wt %, a
thermoplastic resin composition having a resin component containing
PPS by 70 to 97 wt % and polyolefin resin by 3 to 30 wt % or a
thermoplastic resin composition whose main component is an aromatic
polyamide resin can be securely joined by injection joining to a
shaped part obtained by subjecting a stainless steel metal part to
the surface treatment according to the present invention and, as a
result, a composite can be manufactured in which a resin and a
metal alloy are integrated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0065] FIG. 1 is a view of a metallic mold schematically
illustrating the process of manufacturing a composite of a metal
and a resin (a stainless steel piece and a resin composition);
[0066] FIG. 2 is an external view schematically illustrating a
composite of a metal and a resin (a stainless steel piece and a
resin composition);
[0067] FIG. 3 is an electron micrograph of the surface of SUS 304
in magnification of 10,000 times that has been etched using a
sulfuric acid aqueous solution as etchant, rinsed with water and
dried;
[0068] FIG. 4 is an electron micrograph of the surface of SUS 304
in magnification of 100,000 times that has been etched using a
sulfuric acid aqueous solution as etchant, rinsed with water and
dried;
[0069] FIG. 5 is an electron micrograph of the surface of SUS 316
in magnification of 10,000 times that has been etched using a
sulfuric acid aqueous solution as etchant, rinsed with water and
dried; and
[0070] FIG. 6 is an electron micrograph of the surface of SUS 316
in magnification of 100,000 times that has been etched using a
sulfuric acid aqueous solution as etchant, rinsed with water and
dried.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0071] The various elements that make up the composite of metal and
resin according to the present invention will now be described in
detail.
[Stainless Steel]
[0072] The "stainless steel" referred to in the present invention
is chromium stainless steel in which chromium (Cr) is added to
iron, Cr--Ni stainless steel in which nickel (Ni) is added in
combination with chromium (Cr) or any other known corrosion
resistant iron alloy that is called stainless steel. Examples
include SUS 405, SUS 429, SUS 403 and other such chromium stainless
steel and SUS 304, SUS 304L, SUS 316, SUS 316L and other such
Cr--Ni stainless steel, as specified by the Japan Industrial
Standards (JIS) and so forth. The stainless steel used in the
present invention is the product of working a stainless steel from
the above list into a specific shape, then chemically etching the
surface and forming a natural oxidized layer or a layer oxidized by
use of an oxidant.
[Chemical Etching of Stainless Steel]
[0073] Most of the various kinds of stainless steel that are
commercially available were developed for the purpose of increasing
corrosion resistance, so they clearly have chemical resistance and
other such characteristics. Known types of metal corrosion include
total surface corrosion, pitting, fatigue corrosion and so on,
while the corrosive used in the present invention should be
selected by trial and error using chemicals that produce total
surface corrosion and choosing the etchant that is best suited to
the task. According to published documents (such as "Handbook of
Chemical Engineering (edited by the Chemical Engineering Society:
Japan)"), all types of stainless steel undergo total surface
corrosion with an aqueous solution of hydrochloric acid or another
such halogenated hydroacid, sulfurous acid, sulfuric acid, a metal
halide or the like. A drawback of a stainless steel that is
resistant to corrosion by many chemicals is that it will be
corroded by halides. This drawback with respect to halides is
diminished for stainless steel to which molybdenum has been added,
stainless steel in which the carbon content has been reduced and so
forth. However, the chemical etchant of stainless steel used in the
present invention is basically an aqueous solution that produces
the above-mentioned total surface corrosion, while to obtain the
optimal etching conditions the immersion conditions should be
varied according to the type of stainless steel rather than
remaining constant in every case.
[0074] A specific example of the treatment conditions will now be
described. First, a commercially available stainless steel
degreaser, iron degreaser, aluminum alloy degreaser or commercially
available general-purpose neutral detergent is procured, an aqueous
solution is prepared with a concentration of a few percent or a
concentration according to the directions given on the product made
by the degreaser manufacturer, the temperature of this aqueous
solution is adjusted to about 40 to 70.degree. C. and the metal is
immersed for 5 to 10 minutes and then rinsed with water.
Specifically, the stainless steel degreasing treatment in the
present invention is a common, known treatment method. For SUS 304,
it is preferable to adjust a sulfuric acid aqueous solution with a
concentration of about 10% to between 60 and 70.degree. C. and
immerse the metal in this solution for a few minutes, which gives
roughness on the micron order. For SUS 316, it is preferable to
adjust a sulfuric acid aqueous solution with a concentration of
about 10 to 15% to between 60 and 70.degree. C. and immerse the
metal in this solution for a few minutes.
[0075] The term "roughness on the micron order" (also called
surface roughness) used by the present inventors refers to a
textured face with an irregular period of about 0.5 to 10 um and
this textured face can be simply measured by a scanning probe
microscope. An actual problem encountered with roughness such as
this is that the depth or height difference of the high and low
spots is often 0.2 to 3 .mu.m. The surface roughness of a textured
face can be automatically measured using a scanning probe
microscope, for example. Surface roughness refers to the surface
profile, which can be represented by a roughness profile as one of
the curves showing the surface profile. This roughness profile is
defined by the mean width of the profile elements (RSm), the
maximum height of the roughness profile (Rz), etc.
[0076] These numerical values are specified by the Japan Industrial
Standards (JIS B 0601: 2001). This Japan Industrial Standard (JIS B
0601: 2001) was produced, translating ISO 4287 issued in 1997 into
Japanese without changing the technical content or specification
table format. The ultrafine textured face on the nanometer level
was observed with an electron microscope in magnification of
100,000 times and in magnification of 10,000 times.
[0077] FIG. 3 is an electron micrograph in magnification of 10,000
times of the surface of a piece of SUS 304 that had been etched
using a 10% sulfuric acid aqueous solution at a temperature of
70.degree. C. as the etchant, rinsed with water and dried. FIG. 4
is an electron micrograph in magnification of 100,000 times. FIG. 5
is an electron micrograph in magnification of 10,000 times of the
surface of a piece of SUS 316 that had been etched using a 10%
sulfuric acid aqueous solution as the etchant, rinsed with water
and dried. FIG. 6 is an electron micrograph in magnification of
100,000 times. As shown in the electron micrographs of FIGS. 3 and
5, the surface of the piece of SUS 316 has a shape such that
amorphous polygons or particulates with a diameter of 20 to 70 nm
are stacked on top of one another with things resembling sloped
gullies in a lava bed. To put this another way, the surface of the
piece of SUS 316 can be envisaged to have a ultrafine textured face
on a level ranging from a few dozen to a few hundred nanometers in
a shape that looks as if large boulders or stones had been stacked
up in a sloped mound and these would crumble down to the bottom on
the occasion of an earthquake, while it can be seen in FIGS. 3 and
5 that the proportion of the area occupied by this ultrafine
textured face in the total area is so high as to be approximately
80 to 100%.
[0078] A halogenated hydroacid, such as a hydrochloric acid aqueous
solution, is suited to etching but when this aqueous solution is
brought to a high temperature, there is the risk that part of the
acid will volatilize and corrode any surrounding iron structures so
that local venting some kind of treatment has to be performed on
the exhaust gas. In this respect, the use of a sulfuric acid
aqueous solution is preferable in terms of cost. Because of the
above situation, a stainless steel substrate that is suited to
joining is one in which substantially the entire surface is covered
with a ultrafine textured face where amorphous polygons or
particulates with a diameter of at least 20 to 70 nm are stacked on
top of one another. Also, while this is only supposition, the
surface of the stainless steel substrate preferably has an
ultrafine textured face in which protrusions with a height, width
and length of at least 10 nm rise up at a spacing period of at
least 10 nm and has a surface roughness in which the height
difference of the bumps made up of the textured face is at least
0.2 um at a period of 0.5 to 10 .mu.m.
[Surface Hardening of Stainless Steel]
[0079] When the above-mentioned stainless steel is thoroughly
washed with water after chemical etching, its surface undergoes
natural oxidation and goes back to being a surface layer that
withstands corrosion, hence as a general rule there is no need for
any special hardening treatment. However, to obtain a good, hard
metal oxidized layer on the surface of the stainless steel, it is
preferable to use a treatment method in which the metal is immersed
in an aqueous solution of an oxidative acid, such as nitric acid or
another such oxidant, namely, nitric acid, sulfuric acid, hydrogen
peroxide, potassium permanganate, sodium chlorate or the like and
then rinsed with water. Once etching or the formation of an oxide
layer has been completed, the surface is dried, which completes the
surface treatment of the stainless steel applied in the present
invention.
[0080] To find the surface treatment method best suited to the
joining referred to in the present invention, it is preferable to
adopt the procedure in which the products by surface treatment
under various conditions are subjected to an injection joining
test, those with the highest joint strength are chosen and the
surface of stainless steel treated under the same conditions as
these is observed with an electron microscope to confirm the
presence of the above-mentioned ultrafine textured face and confirm
the configuration thereof. Naturally, the injection joining test
may be performed after precedent observation with the electron
microscope. In either way, injection joining strength should be
high for stainless steel having a fine structured surface in which
a ultrafine textured face on a level ranging from a few dozen to a
few hundred nanometers is reliably formed and present. This has
already been confirmed by the inventors with magnesium alloys,
aluminum alloys, copper alloys and titanium alloys.
[0081] Let us now discuss the importance of using chemical etching
here. Any method can be used as long as the anticipated surface
shape discussed above is formed but a question occurs as to why
chemical etching is required. This is related to situation where it
is believed that the designed ultrafine textured face can be
achieved with one of the recent sophisticated ultrafine working
methods used today in the manufacture of semiconductors, in which
the material is coated with a photochemical resist or dipped in it
and visible light rays or ultraviolet rays are used for exposure.
However, there are some reasons why chemical etching is
particularly favorable for injection joining other than the
simplicity of operation entailed.
[0082] Specifically, if the chemical etching is carried out under
the right conditions, not only will the appropriate bump period and
the appropriate recess depth be obtained but the fine shape of the
resulting recesses will not be simple and most of the recesses will
have an undercut structure. An undercut structure means that there
are places that cannot be seen inside the recesses when the
recesses are viewed from above in its vertical plane and, if it
were possible to look at these microscopically from the bottom of
the recess, overhanging places would be seen. It should be easily
understood that undercut structures are necessary for injection
joining. In other words, an undercut structure is one in which an
interior space of a recess is so formed as to be wider than the
opening at the surface.
[Resin Composition]
[0083] The resin composition used in the present invention is a
first resin composition whose main component is a polyphenylene
sulfide resin, a second resin composition whose main component is a
polybutylene terephthalate resin or a third resin composition whose
main component is an aromatic polyamide resin. The resin component
of this first resin composition is a resin composition in which a
polyphenylene sulfide resin is the main component and a polyolefin
resin is an auxiliary component. The resin component of this second
resin composition is a resin composition, in which a polybutylene
terephthalate resin is the main component and a polyethylene
terephthalate resin and/or a polyolefin resin is an auxiliary
component. The resin component of this third resin composition is a
resin composition whose main component is a polyamide resin, in
which different kinds of aromatic polyamide resins are mixed, or a
resin composition, in which an aromatic polyamide resin is the main
component, and whose auxiliary component is an aliphatic polyamide
resin.
[0084] The first resin composition preferably contains
polyphenylene sulfide resin by 70 to 97 wt % and polyolefin resin
by 3 to 30 wt %. The second resin composition preferably contains
polybutylene terephthalate resin by 70 to 97 wt % and polyethylene
terephthalate resin and/or polyolefin resin by 3 to 30 wt %. The
third resin composition preferably contains aromatic polyamide
resin by 70 to 95 wt % and aliphatic polyamide resin by 5 to 30 wt
%. Preferably, at least one type of reinforcing fiber selected from
among glass fiber, carbon fiber, nylon fiber and aramid fiber, in a
total amount of 20 to 60 wt % and at least one type of filler
selected from among calcium carbonate, magnesium carbonate, silica,
talc, clay and glass powder are further added to the first resin
composition, the second resin composition or the third resin
composition. Specifically, when these are added, the remaining 40
to 80 wt % of the first resin composition, second resin composition
or third resin composition is resin component. Adding these
reinforcing fibers and fillers allows the linear coefficient of
expansion of the molded resin to be adjusted to 2 to
3.times.10.sup.-5.degree. C..sup.-1 and kept as low as
possible.
[Resin Composition/PPS-based]
[0085] The PPS resin composition will now be discussed. When the
resin component is composed of PPS by 70 to 97% and polyolefin
resin by 3 to 30%, a composite with particularly good joint
strength can be obtained. If the polyolefin resin content is less
than 3%, the effect of adding the polyolefin resin on enhancing
injection joining strength will not be reliable and the same
applies if its content is over 30%. For a PPS resin to which more
than 30% polyolefin resin has been added, the pyrolysis of the
polyolefin resin in the injection barrel of the injection molding
machine will result in an abnormally large amount of gas being
generated, which can hinder even the injection molding itself.
[0086] Any PPS can be used as long as it is classified as PPS,
while one with a melt viscosity of 100 to 30,000 poise as measured
at a temperature of 315.degree. C. and a load of 98 N (10 kgf) with
a Koka type flow tester mounted with a die 1 mm in diameter and 2
mm long is preferable because it will have better moldability and
workability when formed into a resin composition part. Also, the
PPS may be one substituted with amino groups, carboxyl groups or
the like or may be one copolymerized with trichlorobenzene or the
like during polymerization.
[0087] Also, the PPS may be of a linear structure or may have a
branched structure within it and may have undergone heat treatment
in an inert gas, etc. Furthermore, the ions, oligomers or other
such impurities in the PPS may have been reduced by performing a
deionization treatment (acid washing, hot water washing, etc.) or
washing treatment with an organic solvent such as acetone before or
after heating and curing, while its curing may have been promoted
by performing a heat treatment in an oxidative gas upon completion
of the polymerization reaction.
[0088] The polyolefin resin is an ethylene resin, propylene resin
or other such material normally known as a polyolefin resin and may
be a commercially available product. Of these, maleic
anhydride-modified ethylene copolymers, glycidyl
methacrylate-modified ethylene copolymers, glycidyl ether-modified
ethylene copolymers, ethylene alkyl acrylate copolymers or the like
are preferable because a composite with particularly good
bondability can be obtained.
[0089] Examples of maleic anhydride-modified ethylene copolymers
include maleic anhydride graft-modified ethylene copolymers, maleic
anhydride-ethylene copolymers and ethylene-acrylic acid
ester-maleic anhydride ternary copolymers, of which an
ethylene-acrylic acid ester-maleic anhydride ternary copolymer is
preferable because a particularly excellent composite is obtained.
A specific example of an ethylene-acrylic acid ester-maleic
anhydride ternary copolymer is Bondine (made by Arkema, Kyoto,
Japan).
[0090] Examples of glycidyl methacrylate-modified ethylene
copolymers include glycidyl methacrylate graft-modified ethylene
copolymers and glycidyl methacrylate-ethylene copolymers, of which
a glycidyl methacrylate-ethylene copolymer is preferable because a
particularly excellent composite is obtained. A specific example of
a glycidyl methacrylate-ethylene copolymer is Bondfast (made by
Sumitomo Chemical, Tokyo, Japan). Examples of glycidyl
ether-modified ethylene copolymers include glycidyl ether
graft-modified ethylene copolymers and glycidyl ether-ethylene
copolymers and a specific example of an ethylene alkyl acrylate
copolymer is Lotryl (made by Arkema).
[0091] With the composite of the present invention, the resin
composition part preferably contains polyfunctional isocyanate
compound by 0.1 to 6 weight parts and/or epoxy resin by 1 to 25
parts per 100 weight parts of the total resin component including
PPS by 70 to 97 wt % and polyolefin resin by 3 to 30 wt %, because
the joining of the shaped stainless steel and the resin composition
part will be better. A commercially available non-blocked or
blocked polyfunctional isocyanate compound can be used as a
polyfunctional isocyanate compound.
[0092] Examples of polyfunctional non-blocked isocyanate compounds
include 4,4'-diphenylmethane diisocyanate, 4,4'-diphenylpropane
diisocyanate, toluene diisocyanate, phenylene diisocyanate and
bis(4-isocyanate phenyl)sulfone. A polyfunctional blocked
isocyanate compound has two or more isocyanate groups per molecule,
while these isocyanate groups reacted with a volatile active
hydrogen compound, making the material inert at normal temperature.
There is no particular restriction on the type of polyfunctional
blocked isocyanate compound but generally it will have a structure
in which the isocyanate groups are masked by a blocking agent such
as an alcohol, a phenol, .epsilon.-caprolactam, an oxime or an
active methylene compound.
[0093] An example of a polyfunctional blocked isocyanate is
Takenate (made by Mitsui Takeda Chemical, Tokyo, Japan). The epoxy
resin can be any commonly known type such as a bisphenol A type or
a cresol novolac type. An example of a bisphenol A type epoxy resin
is Epikote (made by Japan Epoxy Resin, Tokyo, Japan), while an
example of a cresol novolac type epoxy resin is Epiclon (made by
Dainippon Ink & Chemicals, Tokyo, Japan).
[Resin Composition/PBT-based]
[0094] The PBT resin composition will now be discussed. Preferably,
the resin composition will include not just the above-mentioned
filler but 3 to 30% PET and/or polyolefin resin and 70 to 97% PBT.
Injection joining strength is superior with a PBT resin composition
in which PBT is the main component and PET and/or a polyolefin
resin is an auxiliary component. The same polyolefin resins as
those listed for the PPS resin composition can be used. Joint
strength will be highest when the PET and/or polyolefin resin
accounts for 5 to 20%, while the joint will still not be so weak at
3 to 5% or at 20 to 30%. However, if the amount is more than 30%,
the effect on injection joining strength will be diminished and, if
the PET component is over 25%, an ester interchange reaction with
PBT will be more likely to proceed at the high temperatures in the
injection molding machine, so there is the risk that the strength
of the resin itself will be lowered. Also, if the polyolefin resin
component is over 30%, more gas will be generated and moldability
will tend to be worsened.
[Resin Composition/Aromatic Polyamide Composition]
[0095] The aromatic polyamide used in the third resin composition
will now be described in specific terms. The aromatic polyamide
referred to here can be a polyamide resin synthesized from a
phthalic acid and an aliphatic diamine, such as a polyamide resin
synthesized from terephthalic acid and hexamethylenediamine
(hereinafter referred to as "nylon 6T") or a polyamide resin
synthesized from isophthalic acid and hexamethylenediamine
(hereinafter referred to as "nylon 6I"). One of the third resin
compositions that are favorable for use in the present invention is
one in which a mixture of different kinds of aromatic polyamide
resins is the main component, a typical example of which is a
mixture of the above-mentioned nylon 6T and nylon 6I.
[0096] If two types are mixed, it is preferable for one to be the
main component and the other an auxiliary component. For instance,
if the two combined together account for 100% of the resin
component, then the main component preferably accounts for 70 to
90%. Another of the third resin compositions that are favorable for
use in the present invention is one in which an aromatic polyamide
resin accounts for 75 to 95% of the resin component and an
aliphatic polyamide resin accounts for 5 to 25%. In any case, if
the amounts are outside the above ranges, the result will be drop
in injection joining strength. It is the theory by Ando, one of the
inventors that the crystallization rate during quenching is
probably increasing (in other words, it is surmised that "it may be
approaching to the normal crystallization rate").
[Resin Composition/Filler]
[0097] The resin composition that is used is not limited to the
first resin composition, second resin composition or third resin
composition and at least one type of reinforcing fiber selected
from among glass fiber, carbon fiber, nylon fiber and aramid fiber
in a combined amount of 20 to 60 wt % and at least one type of
filler selected from among calcium carbonate, magnesium carbonate,
silica, talc, clay and glass powder are preferably contained in
addition to the above compositions. The reason is simple and is
that adding these fillers in addition to the resin component lowers
the linear coefficient of expansion of the resin composition to
about 2 to 3.times.10.sup.-5.degree. C..sup.-1. For metal alloys, a
magnesium alloy has a linear coefficient of expansion of about
2.5.times.10.sup.-5.degree. C..sup.-1, which is the maximum in
metal alloys, and stainless steel has a linear coefficient of
expansion of about 1.0 to 1.1.times.10.sup.-5.degree.
C..sup.-1.
[0098] The linear coefficient of expansion of the resin composition
will never reach the level of stainless steel no matter what is
done but, for the resin component alone with no filler contained,
the linear coefficient of expansion is close to
10.times.10.sup.-5.degree. C..sup.-1, which is extremely high, so
slight changes in the environment temperature cause internal stress
to build up at the joint face and over an extended period of time
this can lead to failure. The higher the filler content is, the
more the linear coefficient of expansion is lowered but, if too
much filler is contained, the melt viscosity of the resin
composition will rise and injection molding itself will be
difficult, so the practical limit will be probably 60% regardless
of the type of filler. Also, even if the filler amount is increased
to near this limit, the best that can be achieved is a linear
coefficient of expansion of about 2.times.10.sup.-5.degree.
C..sup.-1. What this means is that the linear coefficients of
expansion of the resin and stainless steel are never going to
match. Consequently, a product that has been integrated by
injection joining suffers from posing problems when subjected to
major temperature changes.
[0099] One way to prevent such impediments or accidents from
happening is to modify the design so that the thickness or
toughness of both materials is not strengthened. For example, if
one of the materials is made thinner, the internal strain produced
by the difference in linear coefficient of expansion will be
decreased by expansion or contraction of the thinner material (the
weaker material). Methods such as dividing the joint face are also
effective in dispersing the force produced by internal strain to
other areas. In any case, it will be necessary to check whether or
not there is a tendency of the joint strength to be lowered by
subjecting the resulting integrated product to a temperature impact
test.
[Composite Manufacturing Method/Injection Joining Method]
[0100] To summarize the method of the present invention for
manufacturing a composite, a metal part that has undergone the
above-mentioned chemical etching, surface hardening treatment and
so forth is inserted into a metallic mold for injection molding,
the mold is closed, the above-mentioned resin composition is
injected and solidified, after which the mold is opened and the
product is removed, thus a composite being manufactured. This
method for manufacturing a composite is extremely simple and
affords good productivity and is, therefore, suited to mass
production.
[0101] The injection conditions will be described in brief. The
temperature of the metallic mold is preferably on the high side
since solidification will be too fast if the temperature is too
low, even though the resin being used crystallizes more slowly than
ordinary resins. Because of this, as well as experimental results,
100.degree. C. or higher is preferable and 120.degree. C. or higher
is even better. If the temperature is too high, on the other hand,
the injection molding cycle will end up taking longer, so there is
a limit from the standpoint of production efficiency. The inventors
think that 120 to 150.degree. C. is probably a favorable
temperature of the mold. The other conditions, namely, injection
temperature, injection pressure and injection rate are not much
different from those of ordinary injection molding but, if pressed
to say, the injection rate and injection pressure are better on the
high side. This will probably be understood from the explanation of
theory given above.
[0102] Embodiments of the present invention will now be described
through working examples. FIG. 1 is a cross sectional view of a
metallic mold for injection molding 10, schematically illustrating
the process of manufacturing a composite of a metal and a resin (a
stainless steel piece and a resin composition). FIG. 2 is an
exterior view schematically illustrating a composite 7 of a metal
and a resin (a stainless steel piece and a resin composition). The
metallic mold for injection molding 10 shown in FIG. 1 and the
composite 7 shown in FIG. 2 are common to all the working examples.
This mold for injection molding 10 is made up of a movable mold
plate 2 and a stationary mold plate 3 and a resin injector
comprising a pinpoint gate 5, a runner and so forth is constituted
on the stationary mold plate 3 side.
[0103] The formation of the composite 7 is carried out as follows.
First, the movable mold plate 2 is opened and a stainless steel
piece 1 is inserted into the cavity formed between the movable mold
plate 2 and the stationary mold plate 3. After this insertion, the
movable mold plate 2 is closed, resulting in the state before
injection. A molten resin composition is then injected through the
pinpoint gate 5 into the cavity in which the stainless steel was
inserted. Upon being injected, the resin composition 4 is mated
with the stainless steel and fills the cavity that is not occupied
by the stainless steel, which gives the integrated composite 7 made
up of metal and resin. The composite 7 has a joining face 6 between
the stainless steel piece 1 and the resin composition 4 and the
surface area of this joining face 6 is 5 mm.times.10 mm.
Specifically, the surface area of the joining face 6 is 0.5
cm.sup.2. In the following working examples, strength is obtained
using the same basis for the surface area of the joining face.
Strength is obtained under the same conditions in the comparative
examples given below and comparison is made, as well.
WORKING EXAMPLES
[0104] Working examples of the present invention will now be
described in detail.
[0105] The methods for evaluating and measuring the composites
obtained in the following working examples will also be
described.
[Measurement of PPS Melt Viscosity]
[0106] Melt viscosity was measured with a Koka-type flow tester
(CFT-500, made by Shimadzu, Kyoto, Japan) equipped with die having
a diameter of 1 mm and a length of 2 mm, at a measurement
temperature of 315.degree. C. and a load of 98 N (10 kgf).
[0107] (a) X-ray Photoelectron Analyzer (XPS Observation)
[0108] Surface observation method involved the use of photoelectron
analyzer (XPS observation) that analyzes the energy of
photoelectrons emitted from the sample upon irradiation of the same
with X-rays and performs qualitative and quantitative analysis of
elements. This photoelectron analyzer was an Axis-Nova (product
name, made by Kratos Analytical: England and Shimadzu: Japan),
which is a model that allows a surface only a few microns in
diameter to be observed to a depth of a few nanometers.
[0109] (b) Electron Microscopy
[0110] Electron microscopes were mainly used to observe the
substrate surface. These electron microscopes were scanning
electron microscopes (SEM): S-4800 (product name, made by Hitachi,
Tokyo, Japan) and a JSM-6700F (product name, made by JEOL, Tokyo,
Japan), where observations were made at 1 to 2 kV.
[0111] (c) Scanning Probe Microscopy
[0112] A microscope was used mainly to observe the substrate
surface. This microscope is a scanning probe microscope in which a
probe with a pointed tip is used so as to move scanning on the
surface of the substance and the surface condition is enlarged for
observation. This scanning probe microscope was an SPM-9600
(product name; made by Shimadzu, Kyoto, Japan).
[Measurement of Composite Joining Strength]
[0113] Tensile stress was measured by pulling the composite 7 in a
tensile tester to impart shearing force and the breaking force at
break was termed the shear stress. This tensile tester was a Model
1323 (product name; made by Aikoh Engineering, Tokyo, Japan) and
the shear was measured at a pulling rate of 10 mm/minute.
PREPARATIONS EXAMPLE 1
PS Composition Preparation Example
[0114] 6214 g of Na.sub.2S2.9H.sub.2O and 17,000 g of
N-methyl-2-pyrrolidone were supplied to a 50 liter autoclave
equipped with a stirrer. The temperature was gradually raised to
205.degree. C. while stirring the system under a nitrogen gas flow
and 1355 g of water was distilled off. This system was cooled to
140.degree. C., after which 7160 g of p-dichlorobenzene and 5000 g
of N-methyl-2-pyrrolidone were added and the system was sealed
under a nitrogen gas flow. The temperature of the system was raised
to 225.degree. C. over 2 hours, the system was polymerized for 2
hours at 225.degree. C., then the temperature was raised to
250.degree. C. over 30 minutes and polymerization was conducted for
another 3 hours at 250.degree. C. Upon completion of the
polymerization, the system was cooled to room temperature and the
polymer was separated in a centrifuge. The solids of the polymer
obtained by this separation were repeatedly washed with warm water
and dried over night at 100.degree. C., which gave PPS with a melt
viscosity of 280 poise (hereinafter referred to as PPS (1)).
[0115] This PPS (1) was cured for 3 hours at 250.degree. C. under a
nitrogen atmosphere to obtain PPS (hereinafter referred to as PPS
(2)). The melt viscosity of the resulting PPS (2) was 400 poise.
6.0 kg of the resulting PPS (2), 1.5 kg of ethylene-acrylic
ester-maleic anhydride ternary copolymer (Bondine TX8030, made by
Arkema) and 0.5 kg of epoxy resin (Epicote 1004, made by Japan
Epoxy Resin) were uniformly mixed preliminarily in a tumbler. After
this, 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,
Tokyo, Japan) was supplied by side feeder so that the added amount
would be 20 wt % while being melt-kneaded in a biaxial extruder
(TEM-35B, made by Toshiba Machine, Shizuoka, Japan) at a cylinder
temperature of 300.degree. C., which gave a pelletized PPS
composition (1). The resulting PPS composition (1) was dried for 5
hours at 175.degree. C.
PREPARATION EXAMPLE 2
Preparation of PPS Composition
[0116] The PPS (1) obtained in Preparation Example 1 was cured for
3 hours at 250.degree. C. under an oxygen atmosphere, which gave
PPS (hereinafter referred to as PPS (3)). The resulting PPS (3) had
a melt viscosity of 1800 poise. 5.98 kg of the resulting PPS (3)
and 0.02 kg of polyethylene (Nipolon Hard 8300A, made by Tosoh,
Tokyo, Japan) were uniformly mixed preliminarily in a tumbler.
After this, glass fiber with an average fiber diameter of 9 .mu.m
and a fiber length of 3 mm (RES03-TP91) was supplied by side feeder
so that the added amount would be 40 wt % while being melt-kneaded
in a biaxial extruder (TEM-35B) at a cylinder temperature of
300.degree. C., which gave a pelletized PPS composition (2). The
resulting PPS composition (2) was dried for 5 hours at 175.degree.
C.
PREPARATION EXAMPLE 3
Preparation of PPS Composition
[0117] 7.2 kg of the PPS (2) obtained in Preparation Example 1 and
0.8 kg of glycidyl methacrylate-ethylene copolymer (Bondfast E,
made by Sumitomo Chemical) were uniformly mixed preliminarily in a
tumbler. After this, glass fiber with an average fiber diameter of
9 .mu.m and a fiber length of 3 mm (RES03-TP91) was supplied by
side feeder so that the added amount would be 20 wt % while being
melt-kneaded in a biaxial extruder (TEM-35B) at a cylinder
temperature of 300.degree. C., which gave a pelletized PPS
composition (3). The resulting PPS composition (3) was dried for 5
hours at 175.degree. C.
PREPARATION EXAMPLE 4
Preparation of PPS Composition
[0118] 4.0 kg of the PPS (2) obtained in Preparation Example 1 and
4.0 kg of ethylene-acrylic ester-maleic anhydride ternary copolymer
(Bondine TX8030, made by Arkema) were uniformly mixed preliminarily
in a tumbler. After this, glass fiber with an average fiber
diameter of 9 .mu.m and a fiber length of 3 mm (RES03-TP91) was
supplied by side feeder so that the added amount would be 20 wt %
while being melt-kneaded in a biaxial extruder (TEM-35B) at a
cylinder temperature of 300.degree. C., which gave a pelletized PPS
composition (4). The resulting PPS composition (4) was dried for 5
hours at 175.degree. C.
PREPARATION EXAMPLE 5
Preparation of PBT Composition
[0119] 4.5 kg of PBT resin (Toraycon 1100S, made by Toray) and 0.5
kg of PET resin (TR-4550BH, made by Teijin Kasei, Tokyo, Japan)
were uniformly mixed in a tumbler. After this, glass fiber with an
average fiber diameter of 9 .mu.m and a fiber length of 3 mm
(RES03-TP91) was supplied by side feeder so that the added amount
would be 30 wt % while being melt-kneaded in a biaxial extruder
(TEM-35B) at a cylinder temperature of 270.degree. C., which gave a
pelletized PBT resin composition. This was dried for 3 hours at
140.degree. C. to obtain a PBT composition (1).
PREPARATION EXAMPLE 6
Preparation of PBT Composition
[0120] 6.0 kg of PBT resin (Toraycon 1401X31, made by Toray), 0.7
kg of ethylene-acrylic ester-maleic anhydride ternary copolymer
(Bondine TX8030, made by Arkema) and 0.15 kg of epoxy resin
(Epicote 1004, made by Japan Epoxy Resin) were uniformly mixed
preliminarily in a tumbler. After this, 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 supplied by side feeder so that the
added amount would be 30 wt % while being melt-kneaded in a biaxial
extruder (TEM-35B, made by Toshiba Machine) at a cylinder
temperature of 270.degree. C., which gave a pelletized PBT
composition (2). The resulting PBT composition (2) was dried for 5
hours at 150.degree. C.
PREPARATION EXAMPLE 7
Preparation of PBT Composition
[0121] 6.0 kg of PBT resin (Toraycon 1401X31, made by Toray, Tokyo,
Japan), 0.5 kg of PET resin (TR-4550BH, made by Teijin Kasei), 0.5
kg of ethylene-acrylic ester-maleic anhydride ternary copolymer
(Bondine TX8030, made by Arkema) and 0.1 kg of epoxy resin (Epicote
1004, made by Japan Epoxy Resin) were uniformly mixed preliminarily
in a tumbler. After this, 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 supplied by side feeder so that the added
amount would be 30 wt % while being melt-kneaded in a biaxial
extruder (TEM-35B, made by Toshiba Machine) at a cylinder
temperature of 270.degree. C., which gave a pelletized PBT
composition (3). The resulting PBT composition (3) was dried for 5
hours at 150.degree. C.
PREPARATION EXAMPLE 8
Preparation of Polyamide Resin Composition
[0122] 15 weight parts of an aromatic polyamide resin (nylon 6T)
obtained from hexamethylenediamine and terephthalic acid was mixed
in a tumbler with 85 weight parts of an aromatic polyamide resin
(nylon 6I) obtained from hexamethylenediamine and isophthalic acid.
After this, 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 supplied by side feeder so that the added amount would be 30
weight parts while being melt-kneaded in a biaxial extruder
(TEM-35B, made by Toshiba Machine) at a cylinder temperature of
300.degree. C., which gave a pelletized aromatic polyamide resin
composition (1). The resulting aromatic polyamide resin composition
(1) was dried for 10 hours at 80.degree. C.
PREPARATION EXAMPLE 9
Preparation of Polyamide Resin Composition
[0123] 85 weight parts of an aromatic polyamide resin (nylon 6I)
obtained from hexamethylenediamine and isophthalic acid was mixed
in a tumbler with 15 weight parts of nylon 6 resin. After this,
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
supplied by side feeder so that the added amount will be 30 weight
parts while being melt-kneaded in a biaxial extruder (TEM-35B, made
by Toshiba Machine) at a cylinder temperature of 280.degree. C.,
which gave a pelletized aromatic polyamide resin composition (2).
The resulting aromatic polyamide resin composition (2) was dried
for 10 hours at 80.degree. C.
WORKING EXAMPLE 1
[0124] Commercially available SUS 304 sheeting with a thickness of
1.0 mm was purchased and cut into numerous rectangular pieces
measuring 18 mm.times.45 mm to obtain stainless steel pieces as
metal pieces 1. A hole was formed to pass through the end of each
steel piece, copper wire coated with polyvinyl chloride was passed
through the holes of a dozen or so pieces and the copper wire was
bent so that the stainless steel pieces would not overlap each
other, thus allowing all pieces to be hung up at the same time. An
aqueous solution containing aluminum alloy degreaser (NE-6, made by
Meltex (Tokyo, Japan)) by 7.5% was adjusted to 60.degree. C. and
made ready in a tank, while the above-mentioned stainless steel
pieces were immersed for 5 minutes and thoroughly rinsed with tap
water (Ota City, Gunma, Japan).
[0125] In the next, an aqueous solution containing sulfuric acid
(98% concentration) by 10% and adjusted to 70.degree. C. was made
ready in another tank and the above-mentioned metal pieces were
immersed for 6 minutes and then thoroughly rinsed with deionized
water. They were then dried for 15 minutes in a warm air dryer set
to 90.degree. C. The surface was dark brown in color. The copper
wire was taken out of the stainless steel pieces placed on a clean
aluminum foil and the pieces were wrapped up together, then put in
a plastic bag, sealed and stored. In this work, no fingers touched
the faces to be joined (the end portion on the opposite side from
where each hole was formed).
[0126] Two days later, one of the pieces was cut and observed with
an electron microscope and a scanning probe microscope. The results
of observation with the electron microscope in magnification of
10,000 times and 100,000 times are shown in FIGS. 3 and 4
respectively. How the surface looked can be seen in detail in FIG.
4 and the appearance is such that amorphous polygons or
particulates with a diameter of 20 to 70 nm are stacked on top of
one another with the surface covered with the above-mentioned
ultrafine textured face that looks like gullies. It can be seen in
FIG. 3 that this ultrafine textured face extends over the entire
surface. Observation with the scanning probe microscope revealed a
rough surface covered with a roughness of 0.5 to 3 .mu.m. With XPS,
large amounts of oxygen, iron, nickel and chromium were detected
and small amounts of carbon and sulfur were also found. The surface
layer was therefore considered to be the same as an ordinary
oxidized film on stainless steel.
[0127] One day later the remaining stainless steel pieces were
taken out, the portion with the hole formed was grasped with a
glove so that no oil or the like would adhere and each piece was
inserted into a metallic mold for injection molding. The mold was
closed and the PPS composition (1) obtained in Preparation Example
1 was injected at an injection temperature of 310.degree. C. The
temperature of the metallic mold was 140.degree. C. and 20 of the
integrated composites shown in FIG. 2 were obtained. The size of
the resin part was 10 mm.times.45 mm.times.5 mm and the joining
face 6 measured 10 mm.times.5 mm (0.5 cm.sup.2). These products
were placed for 1 hour in a hot air dryer set at 170.degree. C. on
the day of molding to anneal them and then further one day later
they were subjected to a tensile test, which revealed the average
shear breaking strength to be 25 MPa.
WORKING EXAMPLE 2
[0128] Other than using the PPS composition (2) obtained in
Preparation Example 2 instead of the PPS composition (1) obtained
in Preparation Example 1, stainless steel pieces were produced,
injection molding was performed and composites were obtained by
exactly the same method as in Working Example 1. The composites
thus obtained were annealed for 1 hour at 170.degree. C. In short,
in this experiment a PPS containing only a tiny amount of
polyolefin polymer and a PPS resin composition containing only
filler were used. One day later, ten of these were subjected to a
tensile test, which revealed the average shear breaking strength to
be 13.5 MPa. This was far from Working Example 1 and the difference
in the resin material used showed up in the result.
WORKING EXAMPLE 3
[0129] Other than using the PPS composition (3) obtained in
Preparation Example 3 instead of the PPS composition (1) obtained
in Preparation Example 1, composites were obtained by exactly the
same method as in Working Example 1. The composites were annealed
for 1 hour at 170.degree. C. on the day of molding and two days
later these composites were measured for shear breaking strength
with a tensile tester, the average of which was 20 MPa.
COMPARATIVE EXAMPLE 1
[0130] Other than using the PPS composition (4) obtained in
Preparation Example 4 instead of the PPS composition (1), an
attempt was made to obtain a composite by the same method as in
Working Example 1. That is, in this experiment a PPS resin
composition was used that contained an extremely large amount of
polyolefin polymer. However, a large quantity of gas was generated
during molding and this caused molding to be stopped. In this
experiment the main component of the resin composition was not
PPS.
WORKING EXAMPLE 4
[0131] Other than using the PBT composition (1) obtained in
Preparation Example 5 instead of the PPS composition (1) obtained
in Preparation Example 1, stainless steel pieces were produced,
injection molding was performed and composites were obtained by
exactly the same method as in Working Example 1. The injection
temperature was 280.degree. C., the mold temperature was
140.degree. C. and the annealing conditions for the obtained
composites were 1 hour at 150.degree. C. One day later, these
composites were subjected to a tensile test, which revealed the
shear breaking strength to be an average of 26 MPa for 10
pieces.
WORKING EXAMPLE 5
[0132] Other than using the PBT composition (2) obtained in
Preparation Example 6 instead of the PBT composition (1) obtained
in Working Example 5, stainless steel pieces were produced,
injection molding was performed and composites were obtained by
exactly the same method as in Working Example 5. The annealing
conditions for the obtained composites were also the same. One day
later, these composites were subjected to a tensile test, which
revealed the shear breaking strength to be an average of 23.1 MPa
for 10 pieces.
WORKING EXAMPLE 6
[0133] Other than using the PBT composition (3) obtained in
Preparation Example 7 instead of the PBT composition (1) obtained
in Preparation Example 5, stainless steel pieces were produced,
injection molding was performed and composites were obtained by
exactly the same method as in Working Example 5. The annealing
conditions for the obtained composites were also the same. One day
later, these composites were subjected to a tensile test, which
revealed the shear breaking strength to be an average of 29.1 MPa
for 10 pieces.
WORKING EXAMPLE 7
[0134] Commercially available SUS 304 sheeting was treated part way
in exactly the same manner as in Working Example 1. That is, it was
degreased and rinsed with water, etched with a sulfuric acid
aqueous solution and rinsed with water. A nitric acid aqueous
solution with a concentration of 3% was then made ready, adjusted
to 40.degree. C., the above-mentioned metal pieces were immersed in
this for 3 minutes and thoroughly rinsed with deionized water. They
were then dried for 15 minutes in a warm air dryer set at
90.degree. C. After this, the PPS composition (1) was used to
perform injection joining and the resulting composites were
annealed, all in exactly the same manner as in Working Example 1. A
tensile test conducted one day after the annealing revealed the
average shear breaking strength to be 28.3 MPa.
WORKING EXAMPLE 8
[0135] Commercially available SUS 316 sheeting with a thickness of
1.0 mm was purchased and cut into numerous rectangular pieces
measuring 18 mm.times.45 mm to obtain stainless steel pieces as
metal pieces 1. A hole was formed to pass through the end of each
steel piece, copper wire coated with polyvinyl chloride was passed
through the holes of a dozen or so pieces and the copper wire was
bent so that the stainless steel pieces would not overlap each
other, thus allowing all pieces to be hung up at the same time. An
aqueous solution containing aluminum alloy degreaser (NE-6, made by
Meltex) by 7.5% was adjusted to 60.degree. C. and made ready in a
tank and the above-mentioned stainless steel pieces were immersed
for 5 minutes and thoroughly rinsed with tap water (Ota City,
Gunma, Japan).
[0136] In the next, an aqueous solution containing 98% sulfuric
acid in an amount of 10% and adjusted to 70.degree. C. was made
ready in another tank. The above-mentioned steel pieces were
immersed for 3 minutes and then thoroughly rinsed with deionized
water. They were then dried for 15 minutes in a warm air dryer set
to 90.degree. C. The surface was pale dark brown in color. The
copper wire was taken out of the stainless steel pieces placed on a
clean aluminum foil and the pieces were wrapped up together, then
put in a plastic bag, sealed and stored. In this work, no fingers
touched the faces to be joined (the end portion on the opposite
side from where each hole was formed).
[0137] Two days later, one of the pieces was cut and observed with
an electron microscope and a scanning probe microscope. The results
of observation with the electron microscope in magnitude of 10,000
times and 100,000 times are shown in FIGS. 5 and 6 respectively.
How the surface looked can be seen in detail in FIG. 6, and the
appearance is such that amorphous polygons or particulates with a
diameter of 20 to 50 nm are stacked on top of one another, with the
surface covered with the above-mentioned ultrafine textured face
that looks like gullies. It can be seen in FIG. 5 that this fine
textured face extends over 80 to 90% of the surface. One day later
the remaining stainless steel pieces were taken out, the portion
with the hole formed was grasped with a glove so that no oil or the
like would adhere and each piece was inserted into a metallic mold
for injection molding. The mold was closed and the PPS composition
(1) obtained in Preparation Example 1 was injected at an injection
temperature of 310.degree. C. The temperature of the metallic mold
was 140.degree. C. and 20 of the integrated composites shown in
FIG. 2 were obtained. The size of the resin part was 10 mm.times.45
mm.times.5 mm and the joining face 6 measured 10 mm.times.5 mm (0.5
cm.sup.2). These products were placed for 1 hour in a hot air dryer
set at 170.degree. C. on the day of molding to anneal them and then
one day later they were subjected to a tensile test, which revealed
the average shear breaking strength to be 24 MPa.
WORKING EXAMPLE 9
[0138] Commercially available SUS 301 sheeting with a thickness of
1.0 mm was purchased and cut into numerous rectangular pieces
measuring 18 mm.times.45 mm to obtain stainless steel pieces as
metal pieces 1. A hole was formed to pass through the end portion
of each steel piece, copper wire coated with polyvinyl chloride was
passed through the holes of a dozen or so pieces and the copper
wire was bent so that the stainless steel pieces would not overlap
each other, thus allowing all pieces to be hung up at the same
time. An aqueous solution containing aluminum alloy degreaser
(NE-6, made by Meltex, Tokyo, Japan) by 7.5% was adjusted to
60.degree. C. and made ready in a tank and the above-mentioned
stainless steel pieces were immersed for 5 minutes and thoroughly
rinsed with tap water (Ota City, Gunma, Japan).
[0139] In the next, an aqueous solution containing caustic soda by
1.5% and adjusted to 40.degree. C. was made ready in another tank
and the above-mentioned metal pieces were immersed for 1 minute and
then thoroughly rinsed with water. Then, an aqueous solution
adjusted to 65.degree. C. and containing sulfuric acid (98%
concentration) by 5% and ammonium monohydrodifluoride by 1% was
made ready in another tank and the above-mentioned metal pieces
were immersed in this for 1 minute and then thoroughly rinsed with
deionized water. They were then immersed for 3 minutes in an
aqueous solution containing nitric acid by 3% and adjusted to
40.degree. C. and then thoroughly rinsed with deionized water. They
were then dried for 15 minutes in a warm air dryer set to
90.degree. C. The surface was dark brown in color. The copper wire
was taken out of the stainless steel pieces placed on a clean
aluminum foil and the pieces were wrapped up together, then put in
a plastic bag, sealed and stored. In this work, no fingers touched
the face to be joined (the end portion on the opposite side from
where each hole was formed).
[0140] Two days later, one of the pieces was cut and observed with
an electron microscope and a scanning probe microscope. The results
of observation with the electron microscope in magnitude of 100,000
times reveal that the appearance is such that amorphous polygons or
particulates with a diameter of 20 to 70 nm are stacked on top of
one another with the surface covered with the above-mentioned
ultrafine textured face that looks like gullies. Observation with
the scanning probe microscope revealed a rough surface covered with
a roughness of 1 to 2.5 .mu.m.
[0141] Further one day later the remaining stainless steel pieces
were taken out, the portion with the hole formed was grasped with a
glove so that no oil or the like would adhere and each piece was
inserted into a metallic mold for injection molding. The mold was
closed and the PPS composition (1) obtained in Preparation Example
1 was injected at an injection temperature of 310.degree. C. The
mold temperature was 140.degree. C. and 20 of the integrated
composites shown in FIG. 2 were obtained. The size of the resin
part was 10 mm.times.45 mm.times.5 mm and the joining face 6
measured 10 mm.times.5 mm (0.5 cm.sup.2). These products were
placed for 1 hour in a hot air dryer set at 170.degree. C. on the
day of molding to anneal them and then one day later they were
subjected to a tensile test, which revealed the average shear
breaking strength to be 22 MPa.
WORKING EXAMPLE 10
[0142] Commercially available SUS 430 sheeting with a thickness of
1.0 mm was purchased and cut into numerous rectangular pieces
measuring 18 mm.times.45 mm to obtain stainless steel pieces as
metal pieces 1. A hole was formed to pass through the end of each
steel piece, copper wire coated with polyvinyl chloride was passed
through the holes of a dozen or so pieces and the copper wire was
bent so that the stainless steel pieces would not overlap each
other, thus allowing all pieces to be hung up at the same time. An
aqueous solution containing aluminum alloy degreaser (NE-6, made by
Meltex, Tokyo, Japan) by 7.5% was adjusted to 60.degree. C. and
made ready in a tank and the above-mentioned stainless steel pieces
were immersed for 5 minutes and thoroughly rinsed with tap water
(Ota City, Gunma, Japan).
[0143] In the next, an aqueous solution containing caustic soda by
1.5% and adjusted to 40.degree. C. was made ready in another tank
and the above-mentioned metal pieces were immersed for 1 minute and
then thoroughly rinsed with water. Then, an aqueous solution
adjusted to 65.degree. C. and containing sulfuric acid (98%
concentration) by 10% and ammonium monohydrodifluoride by 1% was
made ready in another tank and the above-mentioned metal pieces
were immersed in this for 3 minute and then thoroughly rinsed with
deionized water. They were then immersed for 3 minutes in an
aqueous solution containing nitric acid by 3% and adjusted to
40.degree. C. and then thoroughly rinsed with deionized water. They
were then dried for 15 minutes in a warm air dryer set to
90.degree. C. The surface was dark brown in color. The copper wire
was taken out of the stainless steel pieces placed on a clean
aluminum foil and the pieces were wrapped up together, then put in
a plastic bag, sealed and stored. In this work, no fingers touched
the surfaces to be joined (the end portion on the opposite side
from where each hole was made).
[0144] One week after the above, the stainless steel pieces were
taken out, the portion with the hole formed was grasped with a
glove so that no oil or the like would adhere and was inserted into
a metallic mold for injection molding. The mold was closed and the
PPS composition (1) obtained in Preparation Example 1 was injected
at an injection temperature of 310.degree. C. The temperature of
the metallic mold was 140.degree. C. and 20 of the integrated
composites shown in FIG. 2 were obtained. The size of the resin
part was 10 mm.times.45 mm.times.5 mm and the joining face 6
measured 10 mm.times.5 mm (0.5 cm.sup.2). These products were
placed for 1 hour in a hot air dryer set at 170.degree. C. on the
day of molding to anneal them and then one day later they were
subjected to a tensile test, which revealed the average shear
breaking strength to be 20 MPa.
WORKING EXAMPLE 11
[0145] Commercially available SUS 403 sheeting with a thickness of
1.0 mm was purchased and cut into numerous rectangular pieces
measuring 18 mm.times.45 mm to obtain stainless steel pieces as
metal pieces 1. A hole was formed to pass through the end of each
steel piece, copper wire coated with polyvinyl chloride was passed
through the holes of a dozen of or so pieces and the copper wire
was bent so that the stainless steel pieces would not overlap each
other, thus allowing all pieces to be hung up at the same time. An
aqueous solution containing aluminum alloy degreaser (NE-6, made by
Meltex, Tokyo, Japan) by 7.5% was adjusted to 60.degree. C. and
made ready in a tank and the above-mentioned stainless steel pieces
were immersed for 5 minutes and thoroughly rinsed with tap water
(Ota City, Gunma, Japan).
[0146] In the next, an aqueous solution containing caustic soda by
1.5% and adjusted to 40.degree. C. was made ready in another tank
and the above-mentioned metal pieces were immersed for 1 minute and
then thoroughly rinsed with water. Then, an aqueous solution
adjusted to 65.degree. C. and containing sulfuric acid (98%
concentration) by 10% and ammonium monohydrodifluoride by 1% was
made ready in a separate tank and the above-mentioned metal pieces
were immersed in this for 1.5 minute and then thoroughly rinsed
with deionized water. They were then immersed for 3 minutes in an
aqueous solution containing nitric acid by 3% and adjusted to
40.degree. C. and then thoroughly rinsed with deionized water. They
were then dried for 15 minutes in a warm air dryer set to
90.degree. C. The surface was dark brown in color. The copper wire
was taken out of the stainless steel pieces placed on a clean
aluminum foil and the pieces were wrapped up together, then put in
a plastic bag, sealed and stored. In this work, no fingers touched
the surfaces to be joined (the end portion on the opposite side
from where each holes was formed).
[0147] One week after the above, the stainless steel pieces were
taken out, the portion with the hole formed was grasped with a
glove so that no oil or the like would adhere and each piece was
inserted into a metallic mold for injection molding. The mold was
closed and the PPS composition (1) obtained in Preparation Example
1 was injected at an injection temperature of 310.degree. C. The
temperature of the metallic mold was 140.degree. C. and 20 of the
integrated composites shown in FIG. 2 were obtained. The size of
the resin part was 10 mm.times.45 mm.times.5 mm and the joining
face 6 measured 10 mm.times.5 mm (0.5 cm.sup.2). These products
were placed for 1 hour in a hot air dryer set at 170.degree. C. on
the day of molding to anneal them and then one day later they were
subjected to a tensile test, which revealed the average shear
breaking strength to be 18 MPa.
WORKING EXAMPLE 12
[0148] Commercially available SUS 304BA sheeting with a thickness
of 1.0 mm was purchased and cut into numerous rectangular pieces
measuring 18 mm.times.45 mm to obtain stainless steel pieces as
metal pieces 1. A hole was formed to pass through the end of each
steel piece, copper wire coated with polyvinyl chloride was passed
through a dozen of or so pieces and the copper wire was bent so
that the stainless steel pieces would not overlap each other, thus
allowing all pieces to be hung up at the same time. An aqueous
solution containing aluminum alloy degreaser (NE-6, made by Meltex,
Tokyo, Japan) by 7.5% was adjusted to 60.degree. C. and made ready
in a tank and the above-mentioned stainless steel pieces were
immersed for 5 minutes and thoroughly rinsed with tap water (Ota
City, Gunma, Japan).
[0149] In the next, an aqueous solution containing caustic soda by
1.5% and adjusted to 40.degree. C. was made ready in another tank
and the above-mentioned metal pieces were immersed for 1 minute and
then thoroughly rinsed with water. Then, an aqueous solution
adjusted to 65.degree. C. and containing sulfuric acid (98%
concentration) by 5% and ammonium monohydrodifluoride by 1% was
made ready in another tank and the above-mentioned metal pieces
were immersed in this for 8 minute and then thoroughly rinsed with
deionized water. They were then immersed for 3 minutes in an
aqueous solution containing nitric acid by 3% and adjusted to
40.degree. C. and then thoroughly rinsed with deionized water. They
were then dried for 15 minutes in a warm air dryer set to
90.degree. C. The surface was dark brown in color. The copper wire
was taken out of the stainless steel pieces placed on a clean
aluminum foil and the pieces were wrapped up together, then put in
a plastic bag, sealed and stored. In this work, no fingers touched
the surfaces to be joined (the end portion on the opposite side
from where each hole was formed).
[0150] One week after the above, the stainless steel pieces were
taken out, the portion with the hole formed was grasped with a
glove so that no oil or the like would adhere and was inserted into
a metallic mold for injection molding. The mold was closed and the
PPS composition (1) obtained in Preparation Example 1 was injected
at an injection temperature of 310.degree. C. The temperature of
the metallic mold was 140.degree. C. and 20 of the integrated
composites shown in FIG. 2 were obtained. The size of the resin
part was 10 mm.times.45 mm.times.5 mm and the joining face 6
measured 10 mm.times.5 mm (0.5 cm.sup.2). These products were
placed for 1 hour in a hot air dryer set at 170.degree. C. on the
day of molding to anneal them and then one day later they were
subjected to a tensile test, which revealed the average shear
breaking strength to be 22 MPa.
WORKING EXAMPLE 13
[0151] Other than using the aromatic polyamide resin composition
(1) obtained in Preparation Example 8 instead of the PPS
composition (1) obtained in Preparation Example 1, composites were
obtained by the same method as in Working Example 1. The composites
were annealed for 1 hour at 170.degree. C. on the day of the
molding and two days later, these composites were subjected to a
tensile test, which revealed the shear breaking strength to be an
average of 20 MPa.
WORKING EXAMPLE 14
[0152] Other than using the aromatic polyamide resin composition
(2) obtained in Preparation Example 9 instead of the aromatic
polyamide resin composition (1) obtained in Preparation Example 8,
composites were obtained by the same method as in Working Example
13. The composites were annealed for 1 hour at 170.degree. C. on
the day of the molding and two days later, these composites were
subjected to a tensile test, which revealed the shear breaking
strength to be an average of 19 MPa.
WORKING EXAMPLE 15
[0153] Three composites of the PPS composition (1) and SUS 304
obtained by the method of Working Example 1 were subjected to a
temperature impact test. The temperature impact program involved
cycles, each of which consists of holding a temperature of
-55.degree. C. for 30 minutes, raising the temperature to
+150.degree. C. within 5 minutes thereafter, holding the
temperature there for 30 minutes and then lowering the temperature
back to -55.degree. C. within 5 minutes. 1000 cycles were carried
out, after which the composites were taken out of the temperature
impact tester, subjected to a tensile test on the following day and
measured for shear breaking strength, which was found to be an
average of 23 MPa. Assuming that the original value is 25 MPa
obtained in Working Example 1, then the joint strength seems to be
in a level which is not be considered as having been lowered
substantially.
* * * * *