U.S. patent application number 11/806403 was filed with the patent office on 2008-05-08 for storage container, method for molding resin, and method for forming plating film.
This patent application is currently assigned to HITACHI MAXELL, LTD.. Invention is credited to Masato Fukumori, Takaki Nasu, Yoshiyuki Nomura, Atsushi Yusa.
Application Number | 20080107851 11/806403 |
Document ID | / |
Family ID | 38854928 |
Filed Date | 2008-05-08 |
United States Patent
Application |
20080107851 |
Kind Code |
A1 |
Nasu; Takaki ; et
al. |
May 8, 2008 |
Storage container, method for molding resin, and method for forming
plating film
Abstract
A storage container is provided, which includes carbon dioxide
containing a functional material and a container body in which
carbon dioxide has been hermetically contained. Accordingly, a
method for molding a resin, a method for forming a plating film,
and the storage container for carbon dioxide, which are excellent
in the mass productively at low cost, are provided without using
any special high pressure apparatus for producing a supercritical
fluid.
Inventors: |
Nasu; Takaki; (Kawasaki-shi,
JP) ; Yusa; Atsushi; (Ibaraki-shi, JP) ;
Nomura; Yoshiyuki; (Ibaraki-shi, JP) ; Fukumori;
Masato; (Kawasaki-shi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
HITACHI MAXELL, LTD.
IBARAKI-SHI
JP
|
Family ID: |
38854928 |
Appl. No.: |
11/806403 |
Filed: |
May 31, 2007 |
Current U.S.
Class: |
428/35.8 ;
428/35.7; 524/424 |
Current CPC
Class: |
B01F 13/0818 20130101;
B29C 45/1704 20130101; B29C 48/08 20190201; B29C 48/53 20190201;
B29C 48/2886 20190201; B29C 48/295 20190201; B29K 2705/00 20130101;
B29C 48/268 20190201; B29K 2105/0005 20130101; B65D 81/26 20130101;
B65D 81/267 20130101; B29K 2105/16 20130101; B29C 48/29 20190201;
B29C 48/397 20190201; Y10T 428/1355 20150115; B29C 48/395 20190201;
Y10T 428/1352 20150115; B29K 2105/251 20130101; B29C 48/04
20190201; B29C 48/12 20190201; B29C 48/267 20190201; B29C 2045/1722
20130101; B29C 48/022 20190201; B29C 48/40 20190201; B29K 2105/26
20130101; B29C 45/0053 20130101 |
Class at
Publication: |
428/35.8 ;
428/35.7; 524/424 |
International
Class: |
B32B 15/08 20060101
B32B015/08; B32B 1/08 20060101 B32B001/08; B29D 22/00 20060101
B29D022/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 2, 2006 |
JP |
2006-155355 |
Claims
1. A storage container comprising: carbon dioxide which contains a
functional material; and a container body in which the carbon
dioxide has been hermetically contained.
2. The storage container according to claim 1, wherein the
functional material is metallic fine particles.
3. The storage container according to claim 1, wherein the
functional material is one of a hydrophilic material and a
hydrophobic material.
4. The storage container according to claim 1, wherein the
functional material is inorganic fine particles.
5. The storage container according to claim 1, wherein the
functional material is a surfactant.
6. The storage container according to claim 1, wherein the carbon
dioxide includes liquid carbon dioxide having a pressure in a range
of 3 MPa to 7.38 MPa, and the storage container is provided with a
siphon tube through which the liquid carbon dioxide in the
container body is taken out.
7. The storage container according to claim 6, further comprising a
stirring apparatus.
8. The storage container according to claim 7, wherein the stirring
apparatus includes a stirring bar which is provided in the
container body, and a magnetic stirrer which drives the stirring
bar.
9. The storage container according to claim 8, wherein the
container body is formed of a nonmagnetic material.
10. The storage container according to claim 9, wherein the
nonmagnetic material is formed of one material selected from the
group consisting of aluminum, stainless steel, inconel, hastelloy,
and titanium.
11. The storage container according to claim 1, wherein the carbon
dioxide has a pressure in a range of 3 MPa to 15 MPa.
12. A method for molding a resin, comprising: preparing liquid
carbon dioxide containing a functional material; and impregnating
the functional material into the resin by bringing the liquid
carbon dioxide into contact with the resin having a temperature
higher than that of the liquid carbon dioxide.
13. The method for molding the resin according to claim 12, wherein
a state of the resin is controlled so that the liquid carbon
dioxide is changed into one of carbon dioxide in a supercritical
state and high pressure carbon dioxide gas when the liquid carbon
dioxide is brought into contact with the resin.
14. The method for molding the resin according to claim 12, which
is a method for molding a thermoplastic resin using an injection
molding machine provided with a plasticizing cylinder for injecting
a melted resin into a mold, the method for molding the
thermoplastic resin comprising: introducing the liquid carbon
dioxide containing the functional material into a flow front
portion of the plasticizing cylinder to bring the liquid carbon
dioxide into contact with the melted resin in the plasticizing
cylinder so that the functional material is impregnated into the
melted resin; and injecting the melted resin in the plasticizing
cylinder into the mold to fill the mold therewith.
15. The method for molding the resin according to claim 12, which
is a method for molding a thermoplastic resin using an extrusion
molding machine, the method for molding the thermoplastic resin
comprising: bringing the liquid carbon dioxide containing the
functional material into contact with the thermoplastic resin which
is in a melted state or a softened state in the extrusion molding
machine to impregnate the functional material into the
thermoplastic resin; and performing extrusion molding for the
thermoplastic resin into which the functional material has been
impregnated.
16. The method for molding the resin according to claim 12, wherein
the functional material is metallic fine particles.
17. The method for molding the resin according to claim 12, wherein
the functional material is one of a hydrophilic material and a
hydrophobic material.
18. The method for molding the resin according to claim 12, wherein
the functional material is inorganic fine particles.
19. The method for molding the resin according to claim 12, wherein
the functional material is a surfactant.
20. The method for molding the resin according to claim 12, wherein
the preparation of the liquid carbon dioxide containing the
functional material includes preparing a storage container which is
filled with the liquid carbon dioxide containing the functional
material.
21. A method for forming a plating film, comprising: molding a
molded article including metallic fine particles impregnated into a
surface of the molded article by using the method for forming the
resin as defined in claim 16; and forming the plating film by an
electroless plating method on the surface of the molded article
into which the metallic fine particles are has been impregnated.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a storage container filled
with carbon dioxide containing a functional material (modifying
material), and a method for molding a resin and a method for
forming a plating film, by using carbon dioxide containing the
functional material.
[0003] 2. Description of the Related Art
[0004] The electroless plating method has been hitherto widely used
as a method for forming a metal conductive film on a surface of an
electronic device comprised of a plastic structural member. The
electroless plating process for the plastic somewhat varies
depending on, for example, the material of the plastic. However, in
general, the respective steps of resin molding, degreasing of a
molded article, etching, neutralization and wetting, addition of
catalysts, activation of catalysts, and electroless plating are
performed in this order.
[0005] For example, a chromic acid solution or an alkali metal
hydroxide solution is used as the etching solution in the etching
step of the electroless plating process described above, and
results in the factor to increase the cost, because the etching
solution as described above requires any after treatment such as
the neutralization. Further, a highly toxic etchant is used in the
etching step of the electroless plating process described above.
Therefore, a problem arises in relation to the handling in view of
the environment. In Europe, the instruction of RoHS (Restriction of
the use of certain Hazardous Substances in electrical and electric
equipment) has been established, which restricts specified harmful
chemical substances contained in electric and electronic products.
Materials and parts supply manufacturers are required to guarantee
the fact that hexavalent chromium or the like is not contained in
new electric and electronic devices to be introduced into the
European market after Jul. 1, 2006. In view of the circumstances as
described above, the conventional electroless plating process for
the plastic, which involves the large environmental load, is
confronted with the essential task to make the transfer to any
substitutive technique.
[0006] In order to dissolve the problem involved in the
conventional technique for forming the electroless plating film for
the plastic, for example, a novel plastic electroless plating
method, which is based on the use of the supercritical fluid, is
proposed in "Latest Application Technique for Supercritical Fluid"
(written by Teruo HORI, NTS Publication, pp. 250-255 (2004)).
According to the method described in "Latest Application Technique
for Supercritical Fluid", the metal complex can be injected into
the polymer surface by dissolving the organic metal complex in
carbon dioxide in the supercritical state (hereinafter referred to
as "supercritical carbon dioxide" as well) to bring into contact
with various types of polymers. Metallic fine particles are
deposited on the polymer surface by performing the reducing
treatment such as the chemical reducing treatment or the heating
for the polymer into which the metal complex is injected.
Accordingly, the entire polymer surface can be subjected to the
electroless plating. According to this process, it is seen that the
electroless plating process for the plastic having the good surface
roughness can be achieved, in which it is unnecessary to perform
any treatment for the waste liquid.
[0007] The present inventors have suggested, for example, in
Japanese Patent No. 3696878, a method for producing a molded
article in which a functional material such as a metal complex is
dissolved beforehand in supercritical carbon dioxide, and the
functional material is impregnated into the surface of the molded
article during the injection molding by applying the principle
described in "Latest Application Technique for Supercritical
Fluid". In this method, the functional material is impregnated into
the melted resin by bringing the supercritical carbon dioxide, in
which the functional material has been dissolved, into contact with
the melted resin. After that, the injection molding is performed to
produce the molded article.
[0008] A foam molding process is suggested as an injection molding
process industrially practiced by utilizing the supercritical
fluid, for example, in Japanese Patent Application Laid-open No.
2001-150504. In the molding method disclosed in Japanese Patent
Application Laid-open No. 2001-150504, an inert gas such as N.sub.2
or carbon dioxide is used as a foaming agent without using any
conventional chemical foaming agent. The inert gas in the
supercritical state is kneaded with a melted resin. The kneading is
performed while mixing a resin material to be plasticized and
melted and a supercritical fluid such as N.sub.2 or CO.sub.2 in a
screw when the resin material is plasticized and weighed by using
the screw.
[0009] Various methods have been also hitherto suggested as
techniques for modifying the polymer by utilizing the supercritical
fluid in order to provide the highly advanced function such as, for
example, the improvement in the wettability of the surface of the
polymer base material. For example, Japanese Patent Application
Laid-open No. 2001-226874 discloses the method for forming the
hydrophilic fiber surface by bringing dissolving a supercritical
fluid, in which polyalkyl glycol has been dissolved, into contact
with the fiber. Japanese Patent Application Laid-open No.
2002-129464 discloses a batch process to realize the highly
advanced function of a surface of a polymer base material.
Specifically, the supercritical fluid, in which the solute as the
functional material has been previously dissolved, is brought into
contact with the polymer base material in a supercritical state,
i.e., at a high pressure to perform the dyeing.
[0010] Japanese Patent Application Laid-open No. 2002-313750 also
discloses the following method. At first, a mask, in which holes
having desired shapes are formed, is provided on a substrate. Then,
a supercritical fluid, in which a substance (metal complex) to be
adhered onto the substrate has been dissolved, is jetted onto the
mask to form a pattern of not more than 100 .mu.m of the adhered
substance on the substrate.
[0011] Further, for example, a method is also suggested in Japanese
Patent Application Laid-open No. 2005-305945, in which a plating
catalyst core (metal complex) is impregnated into a part of surface
of a polymer base material by using a technique for modifying the
surface of the polymer base material based on the use of a
supercritical fluid, and then, a plating film is formed on the
polymer base material. In Japanese Patent Application Laid-open No.
2005-305945, the following method is suggested as a method for
selectively impregnating the metal complex into the part of the
surface of the polymer base material. At first, the metal complex
is added to a wide area or the entire area of the surface of the
polymer base material. Subsequently, a mold surface, which has a
predetermined concave/convex pattern, is brought into tight contact
with or adhesion to the surface of the polymer base material.
Subsequently, the supercritical fluid is allowed to flow into the
space defined by the mold (concave portion or recess) and the
surface of the polymer base material. The metal complex is
selectively impregnated into only the surface area of the polymer
base material into which the supercritical fluid is allowed to
flow.
[0012] The method, which is disclosed in "Latest Application
Technique for Supercritical Fluid" described above, is the batch
process. Therefore, this method can be industrially practiced when
a large amount of fiber, sheet or the like can be processed in a
high pressure vessel. However, in this principle, the polymer
surface is softened by the supercritical carbon dioxide or the
like, and the supercritical fluid and the metal complex as the
modifying material (functional material) are impregnated into the
polymer. Therefore, when a large-sized injection molding article or
plastic is produced, the method is difficult to be industrially
practiced, because it is difficult to maintain the shape of the
polymer by softening thereof. Further, the high pressure vessel and
the apparatus for generating the supercritical carbon dioxide are
the factors to increase the cost.
[0013] Nitrogen or carbon dioxide in the supercritical state is
also brought into contact with the resin in the melted state or the
solidified state in the techniques disclosed in Japanese Patent No.
3696878 and Japanese Patent Application Laid-open Nos. 2001-150504,
2001-226874, 2002-129464, 2002-313750, and 2005-345945 described
above. The apparatus for generating the supercritical fluid is the
factor to increase the cost in the same manner as in the technique
disclosed in "Latest Application Technique for Supercritical Fluid"
described above.
[0014] More specifically, in the case of the conventional technique
as described above, when carbon dioxide is used as the medium for
dissolving the functional material, it is necessary that the
pressure is previously raised to not less than 7.38 MPa, and the
temperature is raised to not less than 31.degree. C. to provide the
supercritical state. Therefore, the task resides in the long term
reliability of the seal of the piping and the apparatus for
generating the supercritical fluid. Further, it is necessary to
provide a step of pressurizing carbon dioxide and an expensive high
pressure pump and/or a high pressure dissolution tank for
dissolving the solute (functional material). These matters bring
about the factor to increase the cost when the molded article is
mass-produced.
SUMMARY OF THE INVENTION
[0015] The present invention has been made in order to solve the
problems as described above. An object of the present invention is
to provide a method for molding a resin in which a functional
material is impregnated into the surface and/or the interior of a
molded article without using any special high pressure apparatus
for producing the supercritical fluid as the factor to increase the
cost as described above, a method for forming a plating film on the
surface of the resin, and a storage container for carbon dioxide to
be used for the foregoing methods so that a method for forming a
resin, a method for forming a plating film, and a supply source of
carbon dioxide, which involve the low cost and which are excellent
in the mass productivity, are provided.
[0016] According to a first aspect of the present invention, there
is provided a storage container comprising:
[0017] carbon dioxide which contains a functional material; and
[0018] a container body in which the carbon dioxide has been
hermetically contained (the container body is gas-sealed).
[0019] The state of carbon dioxide to be charged into the storage
container of the present invention may be either the supercritical
state or a state in which the temperature is lower than and/or the
pressure is lower than those of the critical point of the
supercritical state (31.degree. C., 7.38 MFa), i.e., a state in
which carbon dioxide gas and liquid carbon dioxide coexist
(hereinafter referred to as "gas-liquid coexisting state",
"gas-liquid intermixed state", or "gas-liquid mixed state" as
well).
[0020] As a result of diligent investigations performed by the
present inventors in relation to the method for molding the resin
based on the use of the supercritical carbon dioxide, the following
fact has been revealed. That is, some functional materials, which
are soluble in the supercritical carbon dioxide or the high
pressure (pressurized) carbon dioxide gas, are also soluble in the
low pressure carbon dioxide in a liquid state. The some functional
material can be preserved (stored) in such a state that the
functional material (modifying material) is dissolved in the liquid
carbon dioxide which is filled in the transportable high pressure
container (storage container) such as a high pressure bomb.
[0021] The present inventors have found out the following fact.
That is, even when the resin in the melted state is allowed to be
in a reduced pressure atmosphere, and then the carbon dioxide in
the liquid state, which does not arrive at the supercritical
condition, is introduced or injected into the melted resin, the
liquid can be introduced or injected into the melted resin in a
high pressure cylinder such as a molding machine. Further, the
present inventors have found out the following fact. That is, in
this situation, the introduced liquid carbon dioxide
instantaneously undergoes the volume expansion due to the contact
with the high temperature resin in the high pressure cylinder or
the like to provide the supercritical state. Carbon dioxide and the
functional material dissolved therein are easily impregnated into
the melted resin.
[0022] Therefore, when the resin is molded by using the storage
container of the present invention, the functional material can be
impregnated into the resin merely by bringing the melted resin into
contact with carbon dioxide in which the functional material has
been dissolved. Therefore, when the resin is molded by using the
storage container of the present invention, it is unnecessary to
separately prepare any special high pressure apparatus for
producing the supercritical fluid unlike the conventional
technique. Therefore, it is possible to provide the method for
molding the resin and the method for forming the plating film in
which the cost is lower and the mass-productivity is excellent.
Further, the storage container of the present invention is
preferably usable as a inexpensive supply source of the functional
material and carbon dioxide.
[0023] Any arbitrary functional material may be dissolved in carbon
dioxide in the storage container of the present invention.
Specifically, it may be used, for example, various dyes, polyalkyl
glycol, fluorine compounds, low molecular weight polymers, and low
molecular weight monomers.
[0024] In the storage container of the present invention, the
functional material may be a hydrophilic material such as polyalkyl
glycol, or a hydrophobic material such as silicone oil and
fluorine-based materials. For example, the wettability of the resin
surface can be improved by introducing a polymer or a monomer
having an amide group or a hydroxyl group including, for example,
polyalkyl glycol, acrylamide, and s-caprolactam. The water-shedding
quality can be added to the resin surface by using, for example,
fluorine-based compounds or silicone oil.
[0025] In the storage container of the present invention, the
functional material may be metallic fine particles of the metal
complex or the precursor of metal oxide. When the metallic fine
particles are used, the metallic fine particles, which serve as the
catalyst core for the electroless plating, can be impregnated into
the surface of the polymer base material. The conductivity and the
thermal conductivity can be added to the polymer base material by
using the metallic fine particles of, for example, the metal
complex or the metal alkoxide to impregnate the metallic fine
particles into the surface of the polymer base material.
[0026] In the storage container of the present invention, the
functional material may be inorganic fine particles. When the
inorganic fine particles of, for example, SiO.sub.2,
Al.sub.2O.sub.3, Cr.sub.2O.sub.3, or TiO.sub.2 are used as the
functional material, it is possible to suppress the coefficient of
thermal expansion of the polymer base material. When the inorganic
fine particles of, for example, SiO.sub.2 are used as the
functional material, it is possible to control the refractive index
of the polymer base material. When the inorganic substance as
described above is used as the functional material, it is desirable
that the precursor of the raw material is used, or any chemical or
physical modification is applied to the inorganic substance so that
the inorganic substance is soluble in the liquid carbon
dioxide.
[0027] In the storage container of the present invention, the
functional material may be a surfactant. When the surfactant is
used as the functional material, the effect is expected to improve
the wettability of the polymer base material and the prevention of
the electrification.
[0028] The material, which is usable as the functional material
other than the materials described above, includes, for example,
ultraviolet stabilizers such as benzophenone and coumarin, aromatic
agents, monomers of various polymers such as methyl methacrylate
and polymerization initiating materials, and chemicals.
[0029] In the present invention, the pressure is arbitrary in the
storage container for the liquid carbon dioxide. However, in order
to sufficiently maintain the solubility of the functional material,
the storage container may be used at least not less than 3 MPa, and
more desirably not less than 5 MPa. In view of the safety and the
quality control of the storage container, the pressure of carbon
dioxide in the storage container may be not more than 15 MPa, and
more desirably not more than 7.38 MPa at which carbon dioxide is in
the supercritical state.
[0030] According to the laws and ordinances in Japan, it is
specified that the filling constant C of the storage container,
which is represented by C=V/G (G: mass of liquefied gas, V:
container internal volume of the bomb), is not more than 1.34. FIG.
6 shows the relationship between the temperature and the pressure
in the storage container when carbon dioxide is filled or charged
in accordance with the provision of the laws and ordinances. When
the temperature is 14.degree. C., then a state is given, in which
the liquid is 90% and the gas coexists in the upper layer in the
storage container, and the pressure is 4.9 MPa. When the
temperature is 22.degree. C., then the entire content of the
container is the liquid, and the pressure is 5.9 MPa. When the
temperature exceeds the critical temperature (31.degree. C.), then
the entire content of the container is the gas or the supercritical
state. It is prescribed that the safety plate bursts when he
temperature is further raised to arrive at a state having the
pressure of 15.7 MP.
[0031] The method is arbitrary to collect and supply carbon dioxide
in which the functional material has been dissolved, from the
storage container filled with carbon dioxide according to the
present invention. Specifically, for example, when carbon dioxide
is in the gas-liquid coexisting state (state which does not arrive
at the critical point of the supercritical state), it is possible
to collect and use only the liquid carbon dioxide, in which the
functional material has been dissolved, with a siphon tube. The
reason thereof will be explained below.
[0032] FIGS. 7 and B show results of the measurement of the
pressure change in the bomb when carbon dioxide is taken out
continuously at a constant flow rate by using the conventional
liquid carbon dioxide bomb filled with 30 kg. FIG. 7 shows the
characteristic obtained when the bomb, which is not provided with
the siphon tube, is used. FIG. 8 shows the characteristic obtained
when the bomb, which is provided with the siphon tube, is used. The
measurement temperature condition was about 14.degree. C. as a
winter environment. The pressure, which is obtained when the bomb
is fully filled, is about 5 MPa at this temperature. As a result
diligent investigations performed by the present inventors, in the
case of the bomb which is not provided with the siphon tube, as
shown in FIG. 7, the pressure in the container is suddenly lowered
in accordance with the progress of the use of carbon dioxide
(elapsed time depicted on the horizontal axis in FIG. 7), and it is
impossible to maintain any constant pressure in the container. On
the other hand, in the case of the bomb which is provided with the
siphon tube, it is possible to selectively collect the liquid phase
existing in the lower layer in the bomb. Therefore, the following
fact has been revealed. That is, when the flow rate is sufficiently
small (for example, 10 [1/min]), as shown in FIG. 8, the pressure
in the container is not suddenly lowered in accordance with the
progress of the use of carbon dioxide (elapsed time depicted on the
horizontal axis in FIG. 8), and it is possible to stably maintain
the pressure.
[0033] In the case of the storage container of the present
invention, it is desirable that the temperature of the storage
container is not more than 31.degree. C. as the critical point of
the supercritical state of carbon dioxide. More favorably, it is
desirable that the temperature is not more than 22.degree. C. at
which the interior of the storage container, which satisfies the
provision of the filling constant C of the bomb, is in the
gas-liquid coexisting state. In this situation, the liquid carbon
dioxide, in which the functional material has been dissolved, can
be supplied from the storage container at a stable pressure of not
more than about 5.9 MPa. In this case, when the amount of use of
the liquid carbon dioxide is increased, then the liquid level of
the liquid surface is lowered, and the amount of the gas is
increased corresponding thereto. Therefore, when the temperature of
the storage container is not more than 22.degree. C., the carbon
dioxide, in which the functional material has been dissolved, can
be always supplied stably at a constant pressure in the liquid
state, which is preferred.
[0034] As shown in FIG. 8, when the flow rate of the liquid carbon
dioxide is smaller, the liquid carbon dioxide can be supplied at a
stable pressure. Therefore, when it is intended to increase the
flow rate of the liquid carbon dioxide to be supplied, the
following method is favorably adopted. That is, the storage
containers are connected in parallel, and the liquid carbon dioxide
is allowed to outflow simultaneously from the respective storage
containers.
[0035] As for the method for collecting and supplying carbon
dioxide in which the functional material has been dissolved, from
the storage container of the present invention, it is also
appropriate to adopt a method in which the temperature and the
pressure of the storage container are increased, other than the
method in which only the liquid phase is taken out from carbon
dioxide in the gas-liquid intermixed state as described above.
However, in this method, for example, when the carbon dioxide,
which is contained in the storage container, is the gas exceeding
the critical temperature or in the supercritical state, it is
inevitable that the pressure is lowered as the carbon dioxide is
consumed. As a result, when the carbon dioxide is consumed, the
solubility of the functional material is changed in the high
pressure container. Therefore, when this method is used, it is
preferable to adopt the following method as a method for
stabilizing the solubility of the functional material and the
supply pressure of carbon dioxide to be supplied, for example, to
the molding machine.
[0036] For example, the following procedure is preferred. At first,
the temperature is set beforehand so that the internal pressure of
the storage container is about 10 to 15 MPa. Then, the internal
pressure of the storage container, which is located in the primary
or upstream side, is once reduced by using, for example, a
pressure-reducing valve. Subsequently, carbon dioxide is supplied
to the apparatus such as the molding machine in a state in which
the temperature and the pressure of carbon dioxide are constant on
the secondary or downstream side of the pressure-reducing valve or
the like. In the case of this method, it is desirable that the
charge amount of the functional material into the storage container
is adjusted so that the solubility of the functional material
contained in the storage container is not more than the saturation
solubility at the pressure and the temperature of carbon dioxide on
the secondary side subjected to the pressure reduction as the
supply pressure to the apparatus. The pressure in the storage
container during the initial filling, is sufficiently higher than
the pressure on the secondary side. Therefore, the functional
material, which has been dissolved in the unsaturated state,
approaches the saturated state in accordance with the consumption
of the carbon dioxide and the functional material in the storage
container. As a result, the deposition of the functional material
is suppressed as well.
[0037] The storage container of the present invention may further
comprise a stirring apparatus in order to stabilize the solubility
of the functional material in the liquid carbon dioxide. An
apparatus may be used as the stirring apparatus, which includes,
for example, a stirring bar which is provided in the container
body, and a magnetic stirrer which is provided outside the
container body in order to drive the stirring bar. In this
arrangement, when the container body of the storage container is
formed of a nonmagnetic material, the stirring bar, which is
contained in the container body, can be rotated by means of the
external magnetic stirrer. Accordingly, it is possible to stabilize
the solubility of the functional material contained in the liquid
carbon dioxide. The nonmagnetic material, which is usable for the
container body of the storage container, includes, for example,
aluminum, stainless steel, inconel, hastelloy, and titanium. An
ultrasonic generator may be provided as the stirring apparatus at
the outside of the container body. In this arrangement, it is
possible to stabilize the solubility of the functional material
contained in the container body by applying the ultrasonic wave to
the liquid carbon dioxide contained in the container body.
[0038] In the storage container of the present invention, an
organic solvent such as alcohol and acetone may be mixed and used
as an auxiliary agent in the container body in order to stabilize
or improve the solubility of the functional material with respect
to carbon dioxide.
[0039] According to a second aspect of the present invention, there
is provided a method for molding a resin, comprising:
[0040] preparing liquid carbon dioxide containing a functional
material; and
[0041] impregnating the functional material into the resin by
bringing the liquid carbon dioxide into contact with the resin
having a temperature higher than that of the liquid carbon
dioxide.
[0042] In the molding method of the present invention, a state of
the resin may be controlled so that the liquid carbon dioxide is
changed into one of carbon dioxide in a supercritical state and
high pressure carbon dioxide gas when the liquid carbon dioxide is
brought into contact with the resin.
[0043] The present inventors have found out, by a verifying
experiment, the fact that the functional material is impregnated
into the resin even when the liquid carbon dioxide, which has been
dissolved with the functional material and which is in the state of
low temperature and/or low pressure of not more than the critical
point of the supercritical state, is brought into contact with the
resin having a temperature higher than that of the liquid carbon
dioxide. This phenomenon is considered as follows. That is, even
when the liquid carbon dioxide is in the state of low temperature
and/or low pressure of not more than the critical point of the
supercritical state, the liquid carbon dioxide instantaneously has
a high temperature by bringing into contact with the melted resin
having the high temperature. When the temperature is raised to be
high while maintaining a constant volume, the high pressure state
or the supercritical state is given. Then, the liquid carbon
dioxide is diffused at a high velocity into the resin.
Alternatively, the following consideration may be made. That is, as
the pressure is raised, for example, by the holding pressure for
the thermoplastic melted resin, the pressure and the diffusibility
of carbon dioxide are improved in the same manner as described
above. Accordingly, the functional material, which has been
dissolved in the liquid carbon dioxide, can be impregnated into the
resin in the heated, melted, or semi-melted state.
[0044] In the molding method of the present invention, any
arbitrary method may be available to impregnate, into the resin,
the carbon dioxide in which the functional material has been
dissolved. For example, the carbon oxide may be impregnated into a
vent-portion of a vent-type screw, i.e., into a physical
pressure-reducing mechanism portion in a plasticizing cylinder of
an extrusion molding machine or an injection molding machine. In
this case, the carbon dioxide and the functional material can be
impregnated into the whole or a part of the melted resin while
plasticizing the resin.
[0045] In the molding method of the present invention, the method
for molding the resin may be a method for molding a thermoplastic
resin based on the use of an injection molding machine provided
with a plasticizing cylinder for injecting a melted resin into a
mold; the method for molding the thermoplastic resin comprising:
introducing the liquid carbon dioxide containing the functional
material into a flow front portion of the plasticizing cylinder to
bring the liquid carbon dioxide into contact with the melted resin
in the plasticizing cylinder so that the functional material is
impregnated into the melted resin; and injecting the melted resin
in the plasticizing cylinder into the mold to fill the mold
therewith.
[0046] In the molding method based on the injection molding of the
present invention, the method is arbitrary to impregnate the
functional material into the flow front portion. However, for
example, the following process may be adopted. At first, when the
injection molding is performed, the screw is moved backwardly in
ordinary cases in accordance with the increase in the internal
pressure of the resin disposed in front of the screw by performing
the plasticization and the weighing while rotating the screw. In
the molding method of the present invention, the screw is moved
backwardly without rotating the screw after the weighing to reduce
the pressure in the melted resin disposed in front of the screw (on
the side of the mold). Subsequently, the liquid carbon dioxide and
the functional material, which are at the pressure higher than the
internal pressure of the melted resin, are impregnated into the
forward end portion (flow front portion) in the melted resin in the
state of reduced pressure. The back pressure at the back of the
screw is raised, and thus the screw is moved frontwardly again. In
accordance with the method as described above, the carbon dioxide,
which is at the high temperature and the high pressure, for
example, in the supercritical state, can be diffused into the flow
front portion of the resin together with the functional material
dissolved in the carbon dioxide. When the injection molding is
performed (the cavity defined in the mold is filled) after
impregnating the functional material into the flow front portion,
the functional material, which is disposed at the flow front
portion, is diffused to the surface of the molded article due to
the fountain effect of the filling resin (skin layer is formed). As
a result, it is possible to mold the injection molding article in
which the functional material is dispersed in the skin layer (is
impregnated into the surface).
[0047] In the molding method of the present invention, the method
for molding the resin may be a method for molding a thermoplastic
resin based on the use of an extrusion molding machine: the method
for molding the thermoplastic resin comprising: bringing the liquid
carbon dioxide containing the functional material into contact with
the thermoplastic resin which is in a melted state or a softened
state in the extrusion molding machine so that the functional
material is impregnated into the thermoplastic resin; and
performing extrusion molding for the thermoplastic resin into which
the functional material has been impregnated.
[0048] In the molding method based on the extrusion molding of the
present invention, for example, the liquid carbon dioxide, in which
the functional material has been dissolved, is firstly introduced
and impregnated from the storage container (for example, the bomb)
filled with the carbon dioxide dissolved with the functional
material into the thermoplastic resin in the melted or softened
state in the extrusion molding machine. In this method, the resin,
into which the functional material has been impregnated, is
subjected to the extrusion molding. The method for impregnating the
liquid carbon dioxide dissolved with the functional material into
the thermoplastic resin in the melted or softened state includes,
for example, the following method. That is, the internal pressure
of the melted resin is reduced at least at a part of the extrusion
die or the extrusion screw provided with the pressure-reducing
mechanism, and the liquid carbon dioxide and the functional
material are continuously or intermittently introduced into the
reduced pressure portion of the resin. Accordingly, the liquid
carbon dioxide, in which the functional material has been
dissolved, is impregnated into the melted resin. When the molding
method as described above is used, it is possible to modify the
surface or the interior of the molded article with the functional
material.
[0049] In the molding method of the present invention, the
preparation of the liquid carbon dioxide containing the functional
material may include preparing a storage container which is filled
with the liquid carbon dioxide containing the functional material.
In the molding method of the present invention, when the storage
container such as the bomb filled with the liquid carbon dioxide
dissolved with the functional material, is used as the supply
source for the liquid carbon dioxide in which the functional
material has been dissolved, the liquid carbon dioxide, in which
the solubility of the functional material is stabilized, can be
supplied more easily.
[0050] The type of the resin capable of being used in the molding
method of the present invention is arbitrary. It is possible to use
thermoplastic resins, thermosetting resins, and photo-curable
resins. Those usable as the thermoplastic resin include, for
example, synthetic fiber such as those based on polyester,
polypropylene, polymethyl methacrylate, polycarbonate, amorphous
polyolefin, polyetherimide, polyethylene terephthalate, liquid
crystal polymer, ABS resin, polyamideimide, biodegradable plastic
such as polylactic acid, nylon resin, and composite materials
thereof. It is also possible to use resin materials kneaded, for
example, with various inorganic fillers including, for example,
glass fiber, carbon fiber, and nanocarbon. Those usable as the
thermosetting resin include, for example, polyimide, silicone
resin, and urethane resin. Those usable as the photo-curable resin
include, for example, acrylic resin and epoxy resin. The materials
as described above can be appropriately selected depending on the
way of use.
[0051] According to a third aspect of the present invention, there
is provided a method for forming a plating film, comprising:
[0052] molding a molded article including metallic fine particles
impregnated into a surface of the molded article by using the
method for forming the resin according to the second aspect of the
present invention; and
[0053] forming the plating film by an electroless plating method on
the surface of the molded article into which the metallic fine
particles have been impregnated.
[0054] In the molding method of the present invention described
above, when the metallic fine particles are used as the functional
material, the metallic fine particles can be dispersed in the
surface of the molded article (impregnate the metallic fine
particles into the surface of the molded article). The metal film
can be formed on the surface of the molded article by means of the
electroless plating method by using the metallic fine particles as
the catalyst core. When the plating method as described above is
used, the satisfactory electroless plating film can be also formed
on any polymer base material (resin material) on which the surface
is hardly roughened by the etching in the case of any conventional
method and on which it has been difficult to form any electroless
plating film having highly tight contact or adhesion
performance.
[0055] According to the storage container of the present invention,
it is possible to supply carbon dioxide in which the functional
material has been dissolved with the inexpensive apparatus without
using any special high pressure apparatus.
[0056] According to the molding method of the present invention,
the functional material can be impregnated into the resin by using
the liquid carbon dioxide at the low pressure and/or the low
temperature of not more than the critical point of the
supercritical state. Therefore, the molded article, in which the
surface and/or the interior is modified with the functional
material, can be produced without using any special high pressure
apparatus to allow carbon dioxide to be in the high pressure state
or the supercritical state. Therefore, the molded article, in which
the surface and/or the interior is modified with the functional
material, can be easily produced at low cost.
[0057] According to the method for forming the plating film of the
present invention, the metallic fine particles can be dispersed
into the surface of the molded article at the stage of molding of
the molded article. The metal film can be formed on the surface of
the molded article by the electroless plating method by using the
metallic fine particles as the catalyst core. Therefore, the
plating film can be easily formed on the surface of the molded
article without using any solvent which involves the large
environmental load. According to the method for forming the plating
film of the present invention, the satisfactory electroless plating
film can be also formed on any polymer base material (resin
material) on which the surface is hardly roughened by the etching
in the case of any conventional method and on which it has been
difficult to form any electroless plating film having highly tight
contact or adhesion performance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0058] FIG. 1 shows a schematic arrangement illustrating a molding
apparatus used in first to third embodiments.
[0059] FIG. 2 shows magnified mold portions of the molding
apparatus shown in FIG. 1, which illustrates the initial step of
filling the cavity with the resin.
[0060] FIG. 3 shows magnified mold portions of the molding
apparatus shown in FIG. 1, which illustrates a state in which the
cavity is completely filled with the resin.
[0061] FIG. 4 shows a schematic arrangement illustrating a molding
apparatus used in fourth and fifth embodiments.
[0062] FIG. 5 shows the pressure dependence of the solubility of
the functional material used in the embodiments.
[0063] FIG. 6 shows the relationship between the temperature and
the pressure of the carbon dioxide bomb.
[0064] FIG. 7 shows the characteristic of the change of the
container internal pressure with respect to the consumption in the
carbon dioxide bomb when any siphon tube is not used.
[0065] FIG. 8 shows the characteristic of the change of the
container internal pressure with respect to the consumption in the
carbon dioxide bomb when the siphon tube is used.
[0066] FIG. 9 shows a flow chart for explaining the method for
molding the resin and the method for forming a plating film on the
molded article in the first embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0067] An explanation will be specifically made below with
reference to the drawings about embodiments of the storage
container, the method for molding the resin, and the method for
forming the plating film according to the present invention.
However, the present invention is not limited thereto.
First Embodiment
[0068] In a first embodiment, an explanation will be made about a
method for molding a resin and a method for forming a plating film
using an injection molding machine, and a storage container for
supplying, to the injection molding machine, liquid carbon dioxide
in which a functional material has dissolved.
[0069] The type of the resin capable of being used in the molding
method of this embodiment is arbitrary. It is possible to use, for
example, thermoplastic resins including, for example, synthetic
fiber such as those based on polyester, polypropylene, polymethyl
methacrylate, polycarbonate, amorphous polyolefin, polyetherimide,
polyethylene terephthalate, liquid crystal polymer, ABS resin,
polyamideimide, polylactic acid, nylon resin, and composite
materials thereof. It is also possible to use resin materials
kneaded, for example, with various inorganic fillers including, for
example, glass fiber, carbon fiber, and nanocarbon. The materials
as described above can be appropriately selected depending on the
way of use. In this embodiment, polycarbonate having a glass
transition temperature of 145.degree. C. was used.
[0070] In this embodiment, hexafluoroacetylacetonato palladium (II)
as the metal complex was used as the functional material to be
dissolved in the liquid carbon dioxide. The type of the functional
material is arbitrary. It is possible to use, for example, dye or
dyestuff, polyalkyl glycol, metallic fine particles of metal
complex or the like, and fluorine compound. The selection of the
functional material can be appropriately determined, for example,
depending on the way of use. FIG. 5 shows the pressure dependence
of the solubility of the metal complex (hexafluoroacetylacetonato
palladium (II)) used in this embodiment with respect to the liquid
carbon dioxide (20.degree. C.). Carbon dioxide is in the
superaritical state under the condition in which the temperature is
31.degree. C. and the pressure is not less than 7.38 MPa. FIG. 5
also shows the pressure dependence of the solubility with respect
to carbon dioxide at 40.degree. C. (gas state).
[0071] The amount of dissolution of the metal complex with respect
to carbon dioxide was determined by the extraction method.
Specifically, at first, the metal complex is charged or put into a
pressure vessel so that the supersaturated state is given. The
pressure is raised to a desired constant pressure to dissolve the
metal complex in carbon dioxide. After that, the internal pressure
of the pressure vessel is constantly retained by a back pressure
valve. In this state, a predetermined amount of carbon dioxide is
allowed to flow and discharge at a constant flow rate into an
alcohol solvent contained in an extraction vessel disposed outside
the pressure vessel by using a syringe pump. The mass of the metal
complex, which is extracted into the alcohol solvent, is regarded
as the dissolution amount, and the amount of carbon dioxide, which
is allowed to flow, is regarded as the solvent amount to calculate
the solubility of the metal complex.
[0072] As clarified from FIG. 5, it has been revealed that the
metal complex used in this embodiment exhibits the solubility to
some extent even in the gas state at 40.degree. C. and not more
than 7 MPa. According to FIG. 5, it is appreciated that the metal
complex used in this embodiment has the satisfactory solubility
with respect to the liquid carbon dioxide at 20.degree. C. as well.
As described above, it is desirable that the material, which also
exhibits the solubility to some extent with respect to the low
pressure carbon dioxide of not more than the critical point
(supercritical state), is used as the functional material to be
used in the present invention.
[Molding Apparatus]
[0073] FIG. 1 shows a schematic arrangement of a molding apparatus
used in this embodiment. As shown in FIG. 1, the molding apparatus
used in this embodiment principally includes an injection molding
machine 100 and a carbon dioxide supply unit 101.
[0074] As shown in FIG. 1, the injection molding machine 100
principally includes a plasticizing cylinder 40 which injects the
melted resin, and a mold 26. The mold 26 is composed of a movable
mold 19 and a fixed mold 18. As shown in FIG. 1, the fixed mold 18
knocks to the movable mold 19 in the mold 26 to define a cavity 20
at the interface between the fixed mold 18 and the movable mold 19.
The injection molding machine 100 of this embodiment is
interconnected to an unillustrated electric toggle mold-claming
mechanism. The movable mold 19 is moved in the horizontal direction
as viewed in the drawing, and thus the mold 26 is opened/closed. As
shown in FIG. 1, an introducing port 8 for liquid carbon dioxide is
provided at a side portion of a flow front portion 11 in the
plasticizing cylinder 40. The other structure of the injection
molding machine 100 is the same as the structure of any
conventional injection molding machine.
[0075] As shown in FIG. 1, the carbon dioxide supply unit 101
principally includes three storage containers 10, a filter 34, a
pressure-reducing valve 60, a first air operate valve 61, a second
air operate valve 62, three pressure gauges 23 to 25, and a piping
7 which connects the constitutive components as described above. As
shown in FIG. 1, the output side (secondary side) of the second air
operate valve 62 is connected via the piping 7 to the introducing
port 8 of the injection molding machine 100.
[0076] In the present invention, in order to maintain carbon
dioxide in the liquid state, it is desirable that the temperature
is controlled so that the piping and the valves, through which the
liquid carbon dioxide is allowed to flow, have the low temperature.
In this embodiment, the entire piping 7, through which carbon
dioxide is allowed to flow, was the double piping (not shown).
Carbon dioxide was allowed to flow through only the piping disposed
on the inner side. Cooling water at 20.degree. C. was allowed to
flow by using an unillustrated chiller through the piping disposed
on the outer side of the double piping. In this way, in this
embodiment, carbon dioxide, which is disposed in the piping and the
valves, was always cooled.
[0077] In this embodiment, the surrounding of the valve 62 was
covered with an unillustrated cooling manifold to cool the manifold
and the valve 62 in order to suppress the increase in the
temperature of the second air operate valve 62 disposed adjacently
to the plasticizing cylinder 40 having the high temperature.
Further, in this embodiment, the piping 12, which is disposed
between the first air operate valve 61 and the second air operate
valve 62, could be instantaneously heated from the outside by means
of an unillustrated infrared lamp.
[0078] As shown in FIG. 1, the storage container 10 principally
includes a container body 1 which is formed of aluminum
(nonmagnetic material) and is gas-sealed, liquid carbon dioxide 2
with which the interior of the container body 1 is filled
(hermetically contained) and in which the functional material has
been dissolved, a siphon tube 3 which is provided to take out the
liquid carbon dioxide 2 from the storage container 10, a stirring
bar 4 which is provided to retain a constant solubility of the
functional material in the liquid carbon dioxide 2, and a magnetic
stirrer 5 which is provided to drive and rotate the stirring bar 4.
In this embodiment, the carbon dioxide, with which the interior of
the container body 1 is filled, is stored in the gas-liquid mixed
state.
[0079] In the molding apparatus of this embodiment, as shown in
FIG. 1, the outflow ports for carbon dioxide of the respective
storage containers 10, each of which is communicated with the
interior of the container body 1 via the siphon tube 3, are
connected to the piping 7 in parallel. In this embodiment, the
outflow port for carbon dioxide of each of the storage containers
10 was in the normally open state.
[0080] The storage container 10 of this embodiment is provided with
the siphon tube 3 to take out only the liquid phase from the
interior of the container body 1 in which carbon dioxide is in the
gas-liquid mixed state. Therefore, as described above, the liquid
carbon dioxide 2, in which the pressure and the solubility are
stable, can be supplied to the injection molding machine 100. In
this embodiment, the container body 1 is formed of aluminum as the
nonmagnetic material. Therefore, the stirring bar 4, which is
enclosed in the container body 1, can be driven and rotated by the
magnetic stirrer 5. In this embodiment, the stirring bar 4 was
always rotated at 250 rpm to agitate the liquid carbon dioxide 2 so
that the temperature in the liquid carbon dioxide 2 and the
solubility of the functional material are uniformized.
[0081] In this embodiment, the pressure of carbon dioxide contained
in the container body 1 is arbitrary. However, in order to maintain
the solubility of the functional material, it is preferable to make
the use at least not less than 3 MPa and more desirably not less
than 5 MPa. In view of the safety of the container body 1 and the
quality control, the pressure is desirably not more than 15 MPa and
more desirably not more than 7.38 MPa (critical point).
[0082] In this embodiment, in order to stabilize the solubility of
the functional material with respect to carbon dioxide contained in
the container body 1, it is desirable that the temperature of the
container body 1 is controlled. Specifically, it is desirable to
make the control to provide the temperature condition under which
carbon dioxide contained in the container body 1 is in the state of
not more than the critical point, i.e., in the gas-liquid mixed
state. In this embodiment, as shown in FIG. 1, the three storage
containers 10 were covered with an adiabatic wall 6. The air
conditioning was performed so that the temperature in the adiabatic
wall 6 is constant to be 21.+-.1.degree. C. Accordingly, the
temperature in the container body 1 regularly filled with the
liquid carbon dioxide 2 was stabilized to make it possible to
continuously and stably supply the liquid carbon dioxide 2 having a
pressure in a range of 5.5 to 6 MPa.
[0083] In this embodiment, it is desirable that the amount of
dissolution (solubility) of the functional material previously
dissolved in the liquid carbon dioxide 2 in the container body 1 is
not more than the saturation solubility at the supply pressure of
the liquid carbon dioxide during the use, in order to maintain the
constant solubility with respect to the liquid carbon dioxide to be
supplied to the injection molding machine 100. This feature will be
explained more specifically below. For example, as shown in FIG. 5,
when the liquid carbon dioxide having a pressure in a range of 5.5
to 6 MPa is supplied to the injection molding machine 100, then the
solubility of the metal complex used in this embodiment with
respect to the liquid carbon dioxide was about 750 mg/L under the
condition of 20.degree. C. and 6 MPa, and the solubility was about
300 mg/L under the condition of 20.degree. C. and 5.5 MPa. That is,
in order to stably supply the liquid carbon dioxide under the
condition of 20.degree. C. and 6 MPa, it is appropriate that the
dissolution amount (charge amount) of the functional material
previously dissolved in the liquid carbon dioxide 2 in the
container body 1 is adjusted so that the solubility is not more
than 750 mg/L. In order to stably supply the liquid carbon dioxide
under the condition of 20.degree. C. and 5.5 MPa, it is appropriate
that the dissolution amount of the functional material previously
dissolved in the liquid carbon dioxide 2 in the container body 1 is
adjusted so that the solubility is not more than 300 mg/L. When the
charge amount of the functional material in the container body 1 is
adjusted as described above, it is possible to suppress the
fluctuation of the supply amount of the functional material which
would be otherwise caused by the slight change of the temperature
and the pressure. Further, it is possible to suppress the excessive
consumption of the functional material. Accordingly, it is possible
to maintain the constant solubility with respect to the liquid
carbon dioxide to be supplied to the injection molding machine
100.
[0084] In this embodiment, the operating pressure (supply pressure)
of carbon dioxide to be introduced into the injection molding
machine 100 was 5.5 MPa as described later on. Therefore, in this
embodiment, 200 mg of the metal complex per 1 L of the liquid
carbon dioxide was dissolved and used. The container, in which 7 kg
of the amount can be maximally charged per one container, was used
for the container body 1. The regular filling amount was 10 liters.
Therefore, the metal complex of 10.times.0.2=2 g was charged per
one container body. In this embodiment, the metal complex was
previously charged into the container, and then the container was
filled with the liquid carbon dioxide. Thus, the metal complex was
dissolved in the liquid carbon dioxide (step S1 in FIG. 9).
[Method for Molding Resin]
[0085] Next, an explanation will be made with reference to FIGS. 1
to 3 and 9 about a method for molding the resin in this
embodiment.
[0086] The liquid carbon dioxide 2, in which the metal complex was
dissolved, was introduced into the injection molding machine 100 as
follows. At first, the liquid carbon dioxide was allowed to outflow
from the three storage containers 10 so that the indication of the
pressure gauge 25 shown in FIG. 1 was within a range of 5.5 to 6
MPa. The pressure was adjusted to 5.5 MPa by means of the
pressure-reducing valve 60. Subsequently, the first air operate
valve 61 was opened. The liquid carbon dioxide, in which the metal
complex was dissolved, was introduced into the piping 12 between
the first air operate valve 61 and the second air operate valve 62
to raise the indication of the pressure gauge 24. In this
embodiment, when the liquid carbon dioxide, in which the metal
complex has been dissolved, is introduced into the plasticizing
cylinder 40 of the injection molding machine 100, then the second
air operate valve 62 is opened in the state in which the first air
operate valve 61 is closed, and the liquid carbon dioxide is
introduced into the melted resin in the pressure-reduced state as
described later on so that the carbon dioxide and the metal complex
are impregnated into the melted resin. That is, in this embodiment,
the amount of introduction of carbon dioxide was controlled in
accordance with the internal volume of the piping 12.
[0087] Subsequently, the screw 41 was rotated as in the
conventional manner, and pellets 15 of the supplied resin were
plasticized and melted. Then, the screw 41 was moved backwardly
while weighing the melted resin at the portion 22 in front of the
screw. The movement of the screw 41 was stopped at a predetermined
weighing position. Subsequently, the screw 41 was further moved
backwardly to reduce the internal pressure of the weighed melted
resin. In this case, the pressure was lowered so that the resin
pressure, which was measured with the internal pressure monitor 16
of the resin, was not more than 1 MPa.
[0088] Subsequently, the second air operate valve 62 was opened.
The liquid carbon dioxide, with which the piping 12 was filled and
in which the metal complex was dissolved, was introduced from the
introducing port 8 into the flow front portion 11 of the
plasticizing cylinder 40 to bring into contact with the melt resin.
In this step, the liquid carbon dioxide and the metal complex were
impregnated into the melted resin (step S2 in FIG. 9). The
indication of the pressure gauge 24 was lowered from 6 MPa to 3 MPa
when the liquid carbon dioxide was introduced. Subsequently, the
second air operate valve 62 was closed. After that, the screw 41
was moved frontwardly by means of the back pressure force to return
the screw 41 to the filling start position. Accordingly, the carbon
dioxide and the metal complex were diffused into the melted resin
at the flow front portion 11. Then, the air piston 21 was driven to
open the shutoff valve 17. The melted resin was injected into the
cavity 20 of the mold 26 defined by the fixed mold 18 and the
movable mold 19 to fill the cavity 20 therewith (step S3 in FIG.
9).
[0089] FIGS. 2 and 3 schematically show the filling situations of
the melted resin in the mold 26 during the injection. FIG. 2
schematically shows the initial filling situation. In this
situation, the metal complex and the carbon dioxide, which are
impregnated into the flow front portion 11, are diffused in the
cavity 20 while reducing the pressure. In this situation, the
melted resin 27 of the flow front portion 11 is filled while
bringing into contact with the mold surface due to the fountain
effect during the filling to form the skin layer.
[0090] Upon the completion of the filling, as shown in FIG. 3, the
layer (skin layer) 27, into which the metal complex is impregnated,
is formed in the vicinity of the surface of the molded article. The
layer, into which the metal complex is hardly impregnated, is
formed at the core layer 28 of the molded article. Therefore, in
the case of the molded article produced in this embodiment, it is
possible to reduce the amount of use of the metal complex, because
the metal complex, which is impregnated into the inside, does not
contribute to the surface function. Further, the foaming, which
would be otherwise caused by the gasification of carbon dioxide,
can be suppressed by increasing the holding pressure of the melted
resin after performing the primary filling as described above. In
the molding method of this embodiment, carbon dioxide is
impregnated into only the flow front portion 11 in the plasticizing
cylinder 40. Therefore, the absolute amount of carbon dioxide is
small with respect to the entire filling resin. Therefore, the
surface characteristic of the molded article is hardly
deteriorated, even when the counter pressure is not applied into
the mold cavity 20.
[0091] In the molded article manufactured by the molding method as
described above, the palladium metal complex was thermally
decomposed, and the fine particles, which were reduced to the metal
element of palladium, were dispersed (impregnated) in the vicinity
of the surface. The surface of the molded article also included
portions in which the metal complex was dispersed without being
reduced.
[Method for Forming Plating Film]
[0092] Next, a plating film was formed on the surface of the molded
article manufactured by the molding method as described above (step
S4 in FIG. 9). Specifically, the plating film was formed as
follows.
[0093] The molded article manufactured in this embodiment was
subjected to the alkali washing and the annealing, and then the
molded article was immersed in an Ni-P electroless plating solution
(Nicoron DK produced by Okuno Chemical Industries Co., Ltd.) to
form a nickel plating film having a thickness of 1 .mu.m on the
surface of the molded article. As a result, the nickel film
(hereinafter referred to as "first plating film" as well), which
had no blister, was successfully formed over the entire surface of
the molded article. After that, a nickel film having a film
thickness of 20 .mu.m was formed on the first plating film by means
of the electroplating method by using, as the electrode, the first
plating film formed by the electroless plating method. The plating
film (nickel film) was formed on the surface of the molded article
manufactured in this embodiment in accordance with the method
described above. The cross-hatch peel test was performed for the
formed plating film. As a result, any exfoliation of the plating
film was not observed. It was revealed that the satisfactory
plating film was formed.
Second Embodiment
[0094] In this embodiment, the injection molding of the resin was
performed by using the same apparatus as the injection molding
apparatus used in the first embodiment. In this embodiment, in the
same manner as in the first embodiment, the first air operate value
61 was opened, and the liquid carbon dioxide, in which the metal
complex was dissolved, was introduced into the piping 12 between
the first air operate value 61 and the second air operate value 62.
Accordingly, the pressure at the pressure gauge 24 was raised to
5.5 MPa which was the same as the primary pressure.
[0095] Subsequently, the infrared lamp was radiated from the
outside of the piping 12 immediately after introducing, into the
piping 12, the liquid carbon dioxide in which the metal complex was
dissolved so that the temperatures of the piping 12 and the carbon
dioxide contained therein were quickly raised. In this situation,
the pressure at the pressure gauge 24 was raised to 14 MPa. As a
result, it was confirmed that the liquid carbon dioxide, which was
introduced into the piping 12, was in the supercritical state, and
the density was highly concentrated. Subsequently, in the same
manner as in the first embodiment, the second air operate value 62
was opened in the state in which the first air operate value 61 was
closed. The supercritical carbon dioxide and the metal complex were
introduced into the plasticizing cylinder 40, and they were
impregnated into the melted resin in the reduced pressure state.
The injection molding was performed in accordance with the same
method as that of the first embodiment except for the step
described above. As a result, a molded article, in which the
metallic fine particles were impregnated into the surface thereof,
was stably obtained in the same manner as in the first
embodiment.
[0096] In this embodiment, the pressure of the liquid carbon
dioxide can be increased in accordance with the inexpensive method
before the liquid carbon dioxide is introduced into the
plasticizing cylinder 40. For example, it is possible to increase
the amounts of introduction of the carbon dioxide and the
functional material into the resin by providing the supercritical
state. Accordingly, the modification efficiency is improved for the
resin.
[0097] In this embodiment, a plating film was formed on the surface
of the molded article in the same manner as in the first
embodiment. As a result, the metal film, which had the satisfactory
tight contact or adhesion, was successfully obtained in the same
manner as in the first embodiment.
Third Embodiment
[0098] In the third embodiment, the injection molding of the resin
was performed by using the same apparatus as the injection molding
apparatus used in the first embodiment. However, in this
embodiment, the air conditioning was performed so that the
temperature in the adiabatic wall 6 is constant to be
40.+-.1.degree. C. Accordingly, the pressure in the container body
1, which was obtained when the container body 1 was fully filled,
was maintained to be about 13 MPa. That is, in this embodiment, the
carbon dioxide contained in the container body 1 was in the
supercritical state (supercritical carbon dioxide) not in the
gas-liquid intermixed state.
[0099] In this embodiment, when the supercritical carbon dioxide
was introduced into the injection molding machine 100, the pressure
of the supercritical carbon dioxide was reduced so that the
indication of the pressure gauge 23 was 6 MPa by using the
pressure-reducing valve 60. The piping passage, which ranges from
the pressure-reducing valve 60 to the second air operate valve 62,
was cooled and temperature-regulated by using an unillustrated
temperature-regulating flow passage so that the temperature of the
piping passage was 20.degree. C.
[0100] The supercritical carbon dioxide, in which the metal complex
was dissolved, was introduced into the plasticizing cylinder 40 to
perform the injection molding in accordance with the same method as
that of the first embodiment except for the step described above.
As a result, a molded article, in which the metallic fine particles
were impregnated into the surface thereof, was stably obtained in
the same manner as in the first embodiment.
[0101] Further, in this embodiment, a plating film was formed by
performing the electroless plating and the electroplating on the
surface of the manufactured molded article in the same manner as in
the first embodiment. As a result, the satisfactory plating film
was successfully formed on the surface of the molded article in the
same manner as in the first embodiment.
Fourth Embodiment
[0102] In a fourth embodiment, an explanation will be made about a
method for molding the resin by using an extrusion molding machine.
Those usable as the extrusion molding method in the present
invention also include the blow molding, the inflation molding or
the like. All of the conventional methods, which include, for
example, the single screw extrusion and the twin screw extrusion,
can be adopted for the mechanism of the extruder as well. The
conventional manufacturing process can be also used in the
post-processes to be performed after the extrusion molding step as
well. It is possible to adopt the multilayer formation and the
drawing or stretching step.
[0103] In this embodiment, the following single screw extrusion
molding machine was used. That is, the extrusion of the resin was
performed while the thickness of the melted resin was thinned and
the area thereof was expanded in a fan-like form by using a die.
After that, the sheet was wound by using a winding mechanism. The
type of the resin usable in this embodiment is arbitrary. In this
embodiment, polycarbonate was used in the same manner as in the
first embodiment.
[0104] In this embodiment, the same metal complex
(hexafluoroacetylacetonato palladium (II)) as the metal complex
used in the first embodiment was used as the functional material.
Various materials as explained in the first embodiment can be used
as the functional material. The functional material can be
appropriately selected depending on the way of use.
[Molding Apparatus]
[0105] FIG. 4 shows a schematic arrangement of a molding apparatus
used in this embodiment. As shown in FIG. 4, the molding apparatus
used in this embodiment principally includes an extrusion molding
machine 200 and a carbon dioxide supply unit 201.
[0106] As shown in FIG. 4, the extrusion molding machine 200
principally includes a plasticizing melting cylinder 42, a hopper
30 which supplies pellets 15 of the resin into the plasticizing
melting cylinder 42, a motor 50 which rotates a single screw 43 in
the plasticizing melting cylinder 42, a die 31 which performs the
extrusion while thinning the thickness of the melted resin and
expanding the melted resin in a fan-like form, and a winding
mechanism section 202. The extrusion molding machine 200 of this
embodiment is provided with introducing ports for carbon dioxide at
two positions. The first introducing port is a first introducing
port 48 in FIG. 4 which is communicated with a portion disposed in
the vicinity of a vent-mechanism section 44 of the single screw 43
at which the melted resin is subjected to the reduction of
pressure. The second introducing port is a second introducing port
49 in FIG. 4 which is communicated with a pressure-reducing section
47 provided between the die 31 and the single screw 43. As shown in
FIG. 4, the cross-sectional area is widened at the
pressure-reducing section 47. Therefore, the pressure of the melted
resin extruded from the single screw 43 is reduced at the
pressure-reducing section 47. The resin temperature at the
pressure-reducing section 47 was adjusted so that the temperature
is lower than the temperatures of those other than the
pressure-reducing section by using an unillustrated band
heater.
[0107] As shown in FIG. 4, the carbon dioxide supply unit 201
principally includes three storage containers 10, a filter 34, a
pressure-reducing valve 60, a flow rate-adjusting unit 9, two
valves 13, 14, two pressure gauges 23, 25, and a piping 7 which
connects the constitutive components as described above. As shown
in FIG. 4, the output side (secondary side) of the valve 13 is
connected to the first introducing port 48 of the extrusion molding
machine 200 via the piping 7, which is communicated with the
vent-mechanism section 44 in the plasticizing melting cylinder 42.
On the other hand, the output side of the valve 14 is connected to
the second introducing port 49 of the extrusion molding machine 200
via the piping 7, which is communicated with the pressure-reducing
section 47 in the plasticizing melding cylinder 42. The storage
container 10, which stores the carbon dioxide dissolved with the
functional material used in this embodiment, is constructed in the
same manner as in the first embodiment.
[Method for Molding Resin]
[0108] Next, an explanation will be made with reference to FIG. 4
about a method for molding the resin in this embodiment.
[0109] The liquid carbon dioxide, in which the metal complex was
dissolved, was introduced into the extrusion molding machine 200 as
follows. At first, the carbon dioxide was allowed to outflow from
the storage container 10 so that the indication of the pressure
gauge 25 shown in FIG. 4 was within a range of 5.5 to 6 MPa. The
pressure was adjusted to 5.5 MPa by using the pressure-reducing
valve 60. Subsequently, the liquid carbon dioxide was allowed to
flow while providing a constant flow rate of the liquid carbon
dioxide by using the flow rate-adjusting unit 9. The piping 7
between the storage container and the valves 13', 14 was filled
with the liquid carbon dioxide in which the metal complex was
dissolved.
[0110] Subsequently, the liquid carbon dioxide, in which the metal
complex was dissolved, was introduced into the plasticizing
cylinder 42 as follows. In this embodiment, the liquid carbon
dioxide, in which the metal complex was dissolved, was introduced
via the first introducing port 48 communicated with the
vent-mechanism section 44 in the plasticizing cylinder 42. At
first, the pellets 15 of the resin were introduced from the hopper
30 into the heated plasticizing cylinder 42, and the pellets 15
were melted by the rotation of the single screw 43 and the motor 50
in the heated plasticizing cylinder 42. Subsequently, the valve 13
was opened to continuously introduce the liquid carbon dioxide
dissolved with the metal complex into the melted resin while
confirming the fact that the internal pressure of the melted resin
was reduced to be lower than the pressure of 5.5 MPa of the liquid
carbon dioxide by using an internal pressure monitor 45 for the
melted resin provided at the lower portion of the vent-mechanism
section 44 at which the melted resin is subjected to the pressure
reduction. Accordingly, the carbon dioxide and the metal complex
were impregnated into the melted resin. The melted resin, in which
the carbon dioxide and the metal complex were impregnated, is
agitated again by the screw 43 at the downstream from the
vent-mechanism section 44. Accordingly, the metal complex can be
diffused uniformly to the entire resin. In this embodiment, the
amount of permeation into the melted resin was adjusted by
throttling the feed amounts of the liquid carbon dioxide and the
metal complex from the carbon dioxide supply unit 201 (specifically
by controlling the flow rate by using the flow rate-adjusting
unit).
[0111] Subsequently, the melted resin, into which the metal complex
was uniformly diffused, was fed to the die 31. The resin was
extruded from the die 31 to the winding mechanism 202 while
thinning the thickness of the melted resin and expanding the melted
resin in a fan-like form by the die 31. A sheet-shaped molded
article 70, into which the metal complex was uniformly diffused,
was manufactured by using the winding mechanism 202. In this
embodiment, the polycarbonate molded article, in which the metal
complex was decomposed in the molded article and the palladium
element was uniformly dispersed, was obtained in accordance with
the molding method as described above. The thermal conductively of
the molded article of this embodiment was investigated. As a
result, it was acknowledged that the thermal conductivity was
improved. Therefore, when the molding method of this embodiment is
used, it is possible to produce, at the lower cost, the molded
article to be used, for example, for a heat sink material.
Fifth Embodiment
[0112] In a fifth embodiment, the liquid carbon dioxide, in which
the metal complex was dissolved, was introduced via the second
introducing port 49 of the extrusion molding machine 200 used in
the fourth embodiment. Except for the above, the molding process is
the same as that in the fourth embodiment. The metal complex used
in this embodiment was also the same as that used in the fourth
embodiment.
[0113] As shown in FIG. 4, the second introducing port 49 of the
extrusion molding machine 200 is communicated with the
pressure-reducing section 47. The cross section of the flow passage
for the melted resin is increased at the pressure-reducing section
47. Therefore, the melted resin, which is extruded from the
plasticizing cylinder 42, is subjected to the pressure reduction at
the pressure-reducing section 47. The temperature is controlled at
the pressure-reducing section 47 by using the band heater so that
the temperature of the melted resin is lowered. In this embodiment,
the valve 14 was opened to continuously introduce the liquid carbon
dioxide dissolved with the metal complex into the melted resin
while confirming the fact that the internal pressure of the melted
resin was lower than the pressure of 5.5 MPa of the liquid carbon
dioxide by using the internal pressure monitor 45 for the resin
provided at the pressure-reducing section 47.
[0114] However, in this embodiment, the agitation is not performed
with the screw for the resin and the carbon dioxide; The carbon
dioxide and the metal complex, which are introduced in one
direction, are diffused in the lateral direction as the stretching
or drawing direction of the resin at the die in the plasticizing
cylinder. Therefore, an extrusion sheet 70, in which the metal
complex has been impregnated into the surface on one side, is
molded. In this embodiment, the sheet-shaped polycarbonate molded
article 70, in which the metal complex was decomposed and the
palladium metal element was dispersed in the vicinity of the
surface on one side, was obtained in accordance with the method as
described above. The metal complex was dispersed in the vicinity of
the surface without being reduced at a part of the surface of the
molded article 70.
[0115] Subsequently, the molded article manufactured in this
embodiment was subjected to the alkali washing and the annealing,
and then the molded article was immersed in an Ni-P electroless
plating solution (Nicoron DK produced by Okuno Chemical Industries
Co., Ltd.) to form a nickel plating film having a thickness of 1
.mu.m. As a result, the nickel film (hereinafter referred to as
"first plating film" as well), which had no blister, was
successfully formed over the entire surface of the molded article.
After that, a nickel film having a film thickness of 20 .mu.m was
formed on the first plating film by means of the electroplating
method by using, as the electrode, the first plating film formed by
the electroless plating method. The plating film (nickel film) was
formed on the surface of the molded article manufactured in this
embodiment in accordance with the method described above. The
cross-hatch peel test was performed for the formed plating film. As
a result, any exfoliation of the plating film was not observed. It
was revealed that the satisfactory plating film was formed.
[0116] According to the storage container of the present invention,
the carbon dioxide, in which the functional material has been
dissolved, can be supplied by using the inexpensive apparatus
without using any special high pressure apparatus. Therefore, the
storage container of the present invention is preferably usable as
the supply source for the carbon dioxide and the functional
material capable of being used when the fiber or the molded article
is modified and processed by using the carbon dioxide in which the
functional material has been dissolved.
[0117] In the molding method of the present invention, the
functional material can be impregnated into the resin by using the
liquid carbon dioxide having the low temperature and the low
pressure. Therefore, the molded article, in which the surface or
the interior has been modified with the functional material, can be
produced easily and inexpensively without using any special high
pressure apparatus for allowing the carbon dioxide to be in the
high pressure state or the supercritical state. In the molding
method of the present invention, it is possible to simultaneously
perform the molding process and the surface-modifying method for
the resin by using the liquid carbon dioxide as the solvent.
Therefore, the molding method of the present invention is preferred
as the method for producing the molded article modified with the
functional material.
[0118] In the method for forming the plating film of the present
invention, it is possible to simultaneously perform the molding
process and the pretreatment process for the clean electroless
plating. Therefore, the method is more preferred as the method for
forming the plating film. In the method for forming the plating
film of the present invention, the satisfactory plating film can be
formed even on the polymer base material (resin material) for which
the surface has been hardly roughened by the etching in the case of
the conventional plating method and it has been difficult to form
any electroless plating film having the highly tight contact or
adhesion. Therefore, the method for forming the plating film of the
present invention is the method for forming the plating film which
is applicable to all of the fields.
* * * * *