U.S. patent application number 17/108842 was filed with the patent office on 2021-05-27 for silicon compound-coated metal particles.
This patent application is currently assigned to M. TECHNIQUE CO., LTD.. The applicant listed for this patent is M. TECHNIQUE CO., LTD.. Invention is credited to Masakazu ENOMURA, Daisuke HONDA.
Application Number | 20210154736 17/108842 |
Document ID | / |
Family ID | 1000005374348 |
Filed Date | 2021-05-27 |
United States Patent
Application |
20210154736 |
Kind Code |
A1 |
ENOMURA; Masakazu ; et
al. |
May 27, 2021 |
SILICON COMPOUND-COATED METAL PARTICLES
Abstract
The present invention relates to silicon-compound-coated fine
metal particles, with which surfaces of fine metal particles,
composed of at least one type of metal element or metalloid
element, are at least partially coated with a silicon compound and
a ratio of Si--OH bonds contained in the silicon-compound-coated
fine metal particles is controlled to be 0.1% or more and 70% or
less. By the present invention, silicon-compound-coated fine metal
particles that are controlled in dispersibility and other
properties can be provided by controlling the ratio of Si--OH bonds
or the ratio of Si--OH bonds/Si--O bonds contained in the
silicon-compound-coated fine metal particles. By controlling the
ratio of Si--OH bonds or the ratio of Si--OH bonds/Si--O bonds, a
composition that is more appropriate for diversifying applications
and targeted properties of silicon-compound-coated fine metal
particles than was conventionally possible can be designed
easily.
Inventors: |
ENOMURA; Masakazu;
(Izumi-shi, JP) ; HONDA; Daisuke; (Izumi-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
M. TECHNIQUE CO., LTD. |
Izumi-shi |
|
JP |
|
|
Assignee: |
M. TECHNIQUE CO., LTD.
Izumi-shi
JP
|
Family ID: |
1000005374348 |
Appl. No.: |
17/108842 |
Filed: |
December 1, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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16306242 |
Nov 30, 2018 |
10882109 |
|
|
PCT/JP2017/020494 |
Jun 1, 2017 |
|
|
|
17108842 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C01P 2006/66 20130101;
C01P 2004/03 20130101; C01G 49/06 20130101; C01P 2006/90 20130101;
C09C 1/24 20130101; C01G 23/04 20130101; B22F 2301/15 20130101;
C01P 2004/50 20130101; B22F 1/0018 20130101; C01G 53/006 20130101;
C01G 49/02 20130101; C01B 33/02 20130101; C01P 2002/82 20130101;
C01P 2002/70 20130101; C01P 2002/01 20130101; C01G 9/02 20130101;
C09C 3/12 20130101; B22F 1/0062 20130101; C01P 2004/04 20130101;
B22F 2304/054 20130101; C01P 2004/62 20130101; C01P 2004/64
20130101; C09D 7/62 20180101; C01P 2002/02 20130101; B22F 2304/056
20130101; B22F 2301/10 20130101; C01P 2002/72 20130101; C01P
2004/80 20130101; C09C 3/06 20130101; C01P 2006/62 20130101; B22F
2302/256 20130101; C01B 13/145 20130101; C09C 3/063 20130101; C09C
1/043 20130101; B22F 2301/255 20130101; C01B 33/325 20130101; C01B
13/14 20130101; C01F 17/206 20200101; C01P 2006/60 20130101 |
International
Class: |
B22F 1/00 20060101
B22F001/00; C01G 49/06 20060101 C01G049/06; C01G 9/02 20060101
C01G009/02; C09C 1/24 20060101 C09C001/24; C01B 33/02 20060101
C01B033/02; C01B 33/32 20060101 C01B033/32; C01G 53/00 20060101
C01G053/00; C09C 3/06 20060101 C09C003/06; C01B 13/14 20060101
C01B013/14; C01F 17/206 20060101 C01F017/206; C01G 49/02 20060101
C01G049/02; C09D 7/62 20060101 C09D007/62; C09C 1/04 20060101
C09C001/04; C09C 3/12 20060101 C09C003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 2, 2016 |
JP |
2016-111346 |
Jun 3, 2016 |
JP |
PCT/JP2016/066542 |
Nov 7, 2016 |
JP |
PCT/JP2016/083001 |
Claims
1. Silicon-compound-coated fine metal particles, wherein surfaces
of fine metal particles are composed of at least one type of metal
element or metalloid element, wherein the silicon-compound-coated
fine metal particles are those with which surfaces of single metal
particles are at least partially coated with a silicon compound, a
primary particle diameter of the metal particles is 1 .mu.m or
less, and a primary particle diameter of the
silicon-compound-coated fine metal particles is 100.5% or more and
190% or less of the primary particle diameter of the metal
particles, or a diameter of aggregates is 1 .mu.m or less, and a
particle diameter of the silicon-compound-coated fine metal
particles is 100.5% or more and 190% or less of the diameter of the
aggregates.
2. Silicon-compound-coated fine metal particles according to claim
1, wherein the silicon compound contains an amorphous silicon
oxide.
3-5. (canceled)
6. The silicon-compound-coated fine metal particles according to
claim 1, wherein the silicon-compound-coated fine metal particles
are core-shell type silicon-compound-coated fine metal particles,
with each of which an entire surface of a single fine metal
particle serving as a core is coated with a silicon compound
serving as a shell.
7. (canceled)
8. The silicon-compound-coated fine metal particles according to
claim 1, wherein the metal element or metalloid element includes at
least one type of element selected from a group consisting of
silver, copper, and nickel.
9-11. (canceled)
12. The silicon-compound-coated fine metal particles according to
claim 1, wherein the silicon-compound-coated fine metal particles
are those obtained by fine metal particles being precipitated and a
silicon compound being coated on the surfaces of the fine metal
particles continuously subsequent to the precipitation between
processing surfaces that are capable of approaching and separating
from each other and rotate relative to each other.
13. The silicon-compound-coated fine metal particles according to
claim 1, wherein the silicon-compound-coated fine metal particles
are silicon-compound-coated fine metal particles, with which
silicon is contained in interiors of the fine metal particles at
least before a heat treatment is applied and, by application of the
heat treatment, the silicon is migrated from the interior toward an
outer circumference of each fine metal particle in comparison to
before application of the heat treatment.
14. (canceled)
15. A coating composition, a composition for transparent material,
a magnetic composition, a conductive composition, a coloring
composition, a reaction composition, or a catalyst composition that
contains the silicon-compound-coated fine metal particles according
to claim 1.
16-20. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of copending application
Ser. No. 16/306,242, filed on Nov. 30, 2018, which was filed as PCT
International Application No. PCT/JP2017/020494 on Jun. 1, 2017,
which claims the benefit under 35 U.S.C. .sctn. 119(a) to Patent
Application No. 2016-111346, filed in Japan on Jun. 2, 2016, and
Patent Application No. PCT/JP2016/066542, filed in Japan on Jun. 3,
2016, and Patent Application No. PCT/JP2016/083001, filed in Japan
on Nov. 7, 2016, all of which are hereby expressly incorporated by
reference into the present application.
TECHNICAL FIELD
[0002] The present invention relates to silicon-compound-coated
fine metal particles.
BACKGROUND ART
[0003] Fine metal particles are materials that are used in a wide
range of applications, including magnetic materials, conductive
materials, coloring materials, catalysts, and the like, and
especially by making them as fine as 1 .mu.m or less, the metal
particles become improved in properties thereof and can become a
composition suitable for use as a dispersion or the like. However,
in any application, in accompaniment with the properties that are
generated or improved as the metal particles are made finer,
explosive reaction due to rapid oxidation in the atmosphere, loss
of properties anticipated of the fine metal particles due to
oxidation, hydroxylation, or the like due to contact with moisture,
or so forth becomes more likely to occur at the same time, making
it difficult to make maximum use of the properties as fine metal
particles.
[0004] Although to solve the above problems, it is effective to
coat surfaces of the fine metal particles with silica or other
silicon compound as described in Patent Literature 1 or Patent
Literature 2, with these prior arts, control of coating state is
difficult in itself such that an originally-anticipated effect of
the fine metal particles is compromised by coating with a silicon
compound or silicon-compound-coated fine metal particles that are
precisely controlled in properties are not obtained, and factors of
properties of fine metal particles coated with a silicon compound
were not clear.
[0005] Although Patent Literature 3 describes a method for
producing coated particles, in which, in order to control
conductivity, coverage with respect to particles is controlled by a
coating amount of silica on surfaces of the metal particles, the
coverage must obviously be increased to increase insulating
property and with silicon-compound-coated fine metal particles that
are thus treated to be high in coverage, there are such problems as
significant decrease in dispersibility in various dispersion media,
non-realization of anticipated effects, and so forth, and
silicon-compound-coated fine metal particles that are reduced as
much as possible in the silica coating amount with respect to fine
metal particles are being demanded from industries as well.
[0006] In regard to silica coating, Patent Literature 4 describes
particles, with which silica-coated metal oxide particles are
subject to further surface treatment with a
hydrophobicity-imparting material, such as dimethylethoxysilane.
However, no disclosure is made whatsoever in regard to
silica-coated fine metal particles, and in regard to silica-coated
metal oxide particles, the particles are merely treated with a
hydrophobicity-imparting material merely to increase dispersibility
in an oil-based dispersion medium, such as polyglycerin
triisostearate, silicone oil, or squalane, for cosmetic purposes.
Also, although it is stated in Patent Literature 4 that a peak seen
at 1150 to 1250 cm.sup.-1 in an infrared absorption spectrum is an
absorption due to bending vibration of Si--OH, the peak should
usually be assigned to an Si--O bond and the statement that it is
due to Si--OH is clearly in error. Also, a ratio of two different
peaks in the infrared absorption spectrum stated in Patent
Literature 4 clearly has no relationship to properties of
silica-coated fine metal particles, and therefore even in Patent
Literature 4, influences that a ratio of Si--OH bonds contained in
silica-coated metal oxides or a ratio of Si--OH bonds with respect
to a ratio of Si--O bonds contained in the particles has on the
properties of the fine particles are not discovered and
silicon-compound-coated fine metal particles that are controlled
precisely in properties are not obtained.
[0007] Also, Patent Literature 5 by the applicant of the present
application describes a method for producing uniform metal
particles using a method for precipitating various nanoparticles,
such as fine metal particles and fine magnetic particles, between
processing surfaces that are capable of approaching and separating
from each other and rotate relative to each other. However, in
Patent Literature 5, although the production of uniform fine metal
particles is described, there is no description regarding
silicon-compound-coated fine metal particles and obviously there is
also no description regarding control of properties of such
silicon-compound-coated fine metal particles, especially
dispersibility of silicon-compound-coated fine metal particles, by
control of Si--O bonds or Si--OH bonds contained in a silicon
compound. That is, nothing is indicated regarding control of
properties expressed by silicon-compound-coated fine metal
particles, and silicon-compound-coated fine metal particles that
are precisely controlled in properties were thus demanded.
PRIOR ART LITERATURE
Patent Literature
[0008] Patent Literature 1: JP 2008-264611
[0009] Patent Literature 2: JP 2007-088156
[0010] Patent Literature 3: JP 2011-219869
[0011] Patent Literature 4: WO 2000/042112
[0012] Patent Literature 5: WO 2009/008393
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0013] In light of such circumstances, an object of the present
invention is to provide silicon-compound-coated fine metal
particles that are controlled in properties. That is, the object is
to coat fine metal particles with a silicon compound and control
the properties for the purpose of maximally improving the
properties that are anticipated of fine metal particles and
compensate for such properties. Use is made of the fact that the
ratio of Si--OH bonds or the ratio of Si--OH bonds/Si--O bonds
inside the silicon compound that is coated changes in accordance
with a method for preparing the silicon-compound-coated fine metal
particles and environmental changes after preparation. The present
inventors have found that the ratio of Si--OH bonds or the ratio of
Si--OH bonds/Si--O bonds contained in the silicon-compound-coated
fine metal particles is controllable in a specific range and by
controlling the ratio of Si--OH bonds or the ratio of Si--OH
bonds/Si--O bonds in the specific range, dispersibility and other
properties of the silicon-compound-coated fine metal particles can
be controlled precisely, and as a result have completed the present
invention. Also, in light of the above circumstances, an object of
the present invention is to provide various compositions using the
silicon-compound-coated fine metal particles that precisely
controlled in properties.
Solution to the Problem
[0014] More specifically, the present invention is
silicon-compound-coated fine metal particles, with which surfaces
of fine metal particles, composed of at least one type of metal
element or metalloid element, are at least partially coated with a
silicon compound and a ratio of Si--OH bonds contained in the
silicon-compound-coated fine metal particles is controlled to be
0.1% or more and 70% or less.
[0015] Also, the present invention is silicon-compound-coated fine
metal particles, with which surfaces of fine metal particles,
composed of at least one type of metal element or metalloid
element, are at least partially coated with a silicon compound, and
a ratio of Si--OH bonds/Si--O bonds that is a ratio of Si--OH bonds
with respect to a ratio of Si--O bonds contained in the
silicon-compound-coated fine metal particles is controlled to be
0.001 or more and 700 or less.
[0016] In the present invention, preferably, the ratio of Si--OH
bonds or the ratio of Si--OH bonds/Si--O bonds contained in the
silicon-compound-coated fine metal particles is controlled by a
functional group changing treatment.
[0017] In the present invention, preferably, the functional group
changing treatment is at least one type of reaction selected from
among a substitution reaction, an addition reaction, an elimination
reaction, a dehydration reaction, a condensation reaction, a
reduction reaction, and an oxidation reaction.
[0018] In the present invention, preferably, the
silicon-compound-coated fine metal particles are those with which
surfaces of single metal particles are at least partially coated
with the silicon compound, a primary particle diameter of the fine
metal particles is 1 .mu.m or less, and a primary particle diameter
of the silicon-compound-coated fine metal particles is 100.5% or
more and 190% or less of the primary particle diameter of the fine
metal particles.
[0019] In the present invention, preferably, the
silicon-compound-coated fine metal particles are core-shell type
silicon-compound-coated fine metal particles, with each of which an
entire surface of a single fine metal particle serving as a core is
coated with the silicon compound serving as a shell.
[0020] In the present invention, preferably, the
silicon-compound-coated fine metal particles are those with which
surfaces of aggregates, each formed by aggregation of a plurality
of fine metal particles, are at least partially coated with the
silicon compound, a diameter of the aggregates is 1 .mu.m or less,
and a particle diameter of the silicon-compound-coated fine metal
particles is 100.5% or more and 190% or less of the diameter of the
aggregates.
[0021] In the present invention, preferably, the metal element or
metalloid element includes at least one type of element selected
from a group consisting of silver, copper, and nickel.
[0022] In the present invention, preferably, the ratio of Si--OH
bonds or the ratio of Si--OH bonds/Si--O bonds is that obtained by
waveform separation of peaks in a wavenumber region of 750
cm.sup.-1 to 1300 cm.sup.-1 in an infrared absorption spectrum of
the silicon-compound-coated fine metal particles measured using an
attenuated total reflection method (ATR method).
[0023] In the present invention, preferably, the Si--OH bonds are
attributed to a peak of greatest area ratio among
Si--OH-bond-derived peaks, obtained by waveform separation of peaks
in a wavenumber region of 750 cm.sup.-1 to 1300 cm.sup.-1 in an
infrared absorption spectrum of the silicon-compound-coated fine
metal particles measured using an attenuated total reflection
method (ATR method) and waveform-separated in a wavenumber region
of 850 cm.sup.-1 to 980 cm.sup.-1, and the ratio of Si--OH bonds is
a ratio of an area of the peak attributed to the Si--OH bonds with
respect to a total area of peaks obtained by waveform separation of
peaks in the wavenumber region of 750 cm.sup.-1 to 1300
cm.sup.-1.
[0024] In the present invention, preferably, the Si--O bonds are
attributed to a peak of greatest area ratio among
Si--O-bond-derived peaks, obtained by waveform separation of peaks
in a wavenumber region of 750 cm.sup.-1 to 1300 cm.sup.-1 in an
infrared absorption spectrum of the silicon-compound-coated fine
metal particles measured using an attenuated total reflection
method (ATR method) and waveform-separated in a wavenumber region
of 1000 cm.sup.-1 or more and 1300 cm.sup.-1 or less, the Si--OH
bonds are attributed to a peak of greatest area ratio among
Si--OH-bond-derived peaks, obtained by waveform separation of peaks
in the wavenumber region of 750 cm.sup.-1 to 1300 cm.sup.-1 in the
infrared absorption spectrum of the silicon-compound-coated fine
metal particles measured using the attenuated total reflection
method (ATR method) and waveform-separated in a wavenumber region
of 850 cm.sup.-1 to 980 cm.sup.-1, and the ratio of Si--OH
bonds/Si--O bonds is a ratio of an area of the peak attributed to
the Si--OH bonds with respect to an area of the peaks attributed to
the Si--O bonds.
[0025] In the present invention, preferably, the
silicon-compound-coated fine metal particles are those obtained by
the fine metal particles being precipitated and the silicon
compound being coated on the surfaces of the fine metal particles
continuously subsequent to the precipitation between processing
surfaces that are capable of approaching and separating from each
other and rotate relative to each other.
[0026] In the present invention, preferably, the
silicon-compound-coated fine metal particles are
silicon-compound-coated fine metal particles, with which silicon is
contained in interiors of the fine metal particles at least before
a heat treatment is applied and, by application of the heat
treatment, the silicon is migrated from the interior toward an
outer circumference of each fine metal particle in comparison to
before application of the heat treatment.
[0027] In the present invention, preferably, dispersibility of the
silicon-compound-coated fine metal particles in a solvent is
controlled by the ratio of the Si--OH bonds being controlled to be
0.1% or more and 70% or less or the ratio of Si--OH bonds/Si--O
bonds being controlled to be 0.001 or more and 700 or less.
[0028] Also, the present invention may be embodied as a coating
composition, a composition for transparent material, a magnetic
composition, a conductive composition, a coloring composition, a
reaction composition, or a catalyst composition that contains the
silicon-compound-coated fine metal particles of the present
invention.
Advantageous Effects of the Invention
[0029] According to the present invention, silicon-compound-coated
fine metal particles that are controlled in dispersibility and
other properties can be provided by controlling a ratio of Si--OH
bonds or a ratio of Si--OH bonds/Si--O bonds contained in the
silicon-compound-coated fine metal particles. By controlling the
ratio of Si--OH bonds or the ratio of Si--OH bonds/Si--O bonds, a
composition that is more appropriate for diversifying applications
and targeted properties of silicon-compound-coated fine metal
particles than was conventionally possible can be designed
easily.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a diagram illustrating STEM mapping results of a
silicon-compound-coated fine silver particle obtained in Example
1-1.
[0031] FIG. 2 is a diagram illustrating line analysis results of
the silicon-compound-coated fine silver particle obtained in
Example 1-1.
[0032] FIG. 3 is a diagram illustrating results of waveform
separation in a wavenumber region of 750 cm.sup.-1 to 1300
cm.sup.-1 of FT-IR measurement results of silicon-compound-coated
fine silver particles obtained in Example 1-7.
[0033] FIG. 4 is a diagram illustrating results of XRD measurements
of the silicon-compound-coated fine silver particles obtained in
Example 1-1.
[0034] FIG. 5 is a TEM photograph observed using a collodion
membrane prepared from an aqueous dispersion liquid of the
silicon-compound-coated fine silver particles obtained in Example
1-1.
[0035] FIG. 6 is a diagram illustrating STEM mapping results of a
silicon-compound-coated, silicon-aluminum-doped fine iron particle
obtained in Example 5-5.
[0036] FIG. 7 is a diagram illustrating results of XRD measurement
of the silicon-compound-coated, silicon-aluminum-doped fine iron
particle obtained in Example 5-5.
[0037] FIG. 8 is a diagram enlarging regions of the XRD measurement
results of the silicon-compound-coated, silicon-aluminum-doped fine
iron particle obtained in Example 5-5 in which peaks were seen to
compare a peak list with peaks of Fe (metal) in a database.
EMBODIMENTS TO CARRY OUT THE INVENTION
[0038] Hereinafter, the present invention will be described by way
of exemplary embodiments with reference to the attached drawings.
However, the aspects of the present invention are not limited to
the embodiments described below.
[0039] (Silicon-Compound-Coated Fine Metal Particle
Composition--1)
[0040] Silicon-compound-coated fine metal particles according to
the present invention are silicon-compound-coated fine metal
particles that are controlled in dispersibility and other
properties by controlling a ratio of Si--OH bonds or a ratio of
Si--OH bonds/Si--O bonds contained in the silicon-compound-coated
fine metal particles. The silicon-compound-coated fine metal
particles according to the present invention are especially
suitable for a coating composition, used for a purpose of coating
onto a coating film or a coated body, a composition for transparent
material, used for a purpose of kneading into or coating onto a
transparent agent, such as a glass, film, or transparent film, a
magnetic composition, used for a purpose of adding to a magnetic
fluid, a magnetic material, or the like, a conductive composition,
used for a purpose of adding to an electronic material, a
semiconductor material, or the like, a coloring composition, used
for a purpose of coloring a coating film, a coated body, a
transparent agent, or the like, or a reaction composition or a
catalyst composition, used as a material for any of various
chemical reactions.
[0041] (Silicon-Compound-Coated Fine Metal Particle
Composition--2)
[0042] The silicon-compound-coated fine metal particles according
to the present invention are silicon-compound-coated fine metal
particles, with which the ratio of Si--OH bonds contained in the
silicon-compound-coated fine metal particles is controlled to be in
a range of 0.1% or more and 70% or less or especially with which
the ratio of Si--OH bonds/Si--O bonds is controlled to be in a
range of 0.001 or more and 700 or less. Dispersibility can thereby
be controlled precisely with respect to a hydrophilic or lipophilic
dispersion medium in a case of use in any of the various
compositions mentioned above. For example, by using the
silicon-compound-coated fine metal particles, with which the ratio
of Si--OH bonds or the ratio of Si--OH bonds/Si--O bonds contained
in the silicon-compound-coated fine metal particles is controlled
with respect to octanol/water partition coefficients of different
dispersion media, properties required of the
silicon-compound-coated fine metal particles can be exhibited
sufficiently in use as an intended composition because the
dispersibility with respect to the dispersion medium is controlled
precisely. The present inventors have found that despite such
control being difficult when the ratio of Si--OH bonds or the ratio
of Si--OH bonds/Si--O bonds contained in the
silicon-compound-coated fine metal particles is outside the
corresponding range mentioned above, such control can be performed
extremely easily when either ratio is within the corresponding
range. Usually with a coated silicon compound, in order to obtain a
satisfactory dispersion state, various functional groups are
treated in accordance with a dispersion medium used, and the
functional groups are selected according to whether the dispersion
medium is an aqueous dispersion medium or a non-aqueous dispersion
medium. Although silicon compounds added with various functional
groups, for example, phenolic hydroxyl groups, carboxylic groups,
carbonyl groups, amino groups, nitro groups, sulfo groups, alkyl
groups, and the like, are used, as particle diameter decreases,
degradation of dispersion state occurs due to accompaniment of
aggregation and it was difficult to achieve the purpose merely by
the selection of the functional groups. Under such circumstances,
it was found that even in a state where various functional groups
are selected, targeted dispersion states could be obtained by
controlling the ratio of Si--OH bonds/Si--O bonds and the present
invention was thereby completed. That is, information on various
bonds are obtained by an FT-IR spectrum and especially among such
information, ratios of areas of peaks attributed to Si--OH bonds
and Si--O bonds, obtained by waveform-separation of peaks in a
wavenumber region of 750 cm.sup.-1 to 1300 cm.sup.-1, can be
controlled to realize the targeted dispersion states. It was found
that suitable use in any of the various compositions mentioned
above is made possible because silicon-compound-coated metal
particles that are precisely controlled in dispersibility with
respect to various solvents can be produced and because properties,
such as stability of the silicon-compound-coated fine metal
particles per se and preservation stability in a powder state, can
be controlled.
[0043] (Silicon-Compound-Coated Fine Metal Particle
Composition--3)
[0044] With the silicon-compound-coated fine metal particles
according to the present invention, by the ratio of Si--OH bonds
contained in the silicon-compound-coated fine metal particles being
controlled to be in the range of 0.1% or more and 70% or less or
the ratio of Si--OH bonds/Si--O bonds being controlled to be in the
range of 0.001 or more and 700 or less, properties, other than the
dispersibility and stabilities mentioned above, such as absorption
properties, transmission properties, reflection properties, plasmon
properties, and the like with respect to ultraviolet rays, visible
rays, near-infrared rays, and other electromagnetic waves are also
controlled to enable suitable use in a transparent agent
composition, fora purpose of use with a glass, film, transparent
resin or the like or a coating composition for a coating film or a
coated body. Also, in a case where silicon-compound-coated fine
metal particles, with which surfaces of fine metal particles,
composed of at least one type of metal element or metalloid
element, are coated with a silicon compound, are used as a magnetic
composition, the particles are formed as nano-size magnetic domains
insulated by the silicon compound and therefore control with
magnetic anisotropies being isolated is enabled and consequently,
control of holding force is enabled as well. That is, the particles
areas suitable as a magnetic composition as never before. The
particles are also suitable as an internal electrode of an
electronic component. For example, in a case of use in an internal
electrode of a laminated ceramic capacitor, a dispersion is
processed into a laminated coating film and thereafter baked in a
reducing atmosphere and in the process of baking, the silicon
compound migrates to a surface layer of the electrode and becomes
formed as a thin insulating film at a boundary between an electrode
layer and a dielectric layer to greatly improve performance of the
laminated ceramic capacitor. Also, in both the case of using the
silicon-compound-coated fine metal particles as the magnetic
composition and in the case of using the particles as the internal
electrode material, slurrying is an important factor and slurrying
in a dispersed state without aggregation in an appropriate
dispersion medium is essential, and the ratio of Si--OH bonds/Si--O
binds influences coating film formation states and states after
baking according to baking conditions. Si--O bonds are significant
in water-repellent or lipophilic tendency, Si--OH bonds are
significant in hydrophilic tendency, and the ratio of these bonds
is indeed a controlling factor in dispersion and is also an
important factor in control of progress of water evaporation and
reduction as well as control of insulating property even at a
baking temperature or under a baking atmosphere.
[0045] Further, in a case of silicon-compound-coated fine metal
particles with semiconductor properties, the particles are
controlled in semiconductor properties, such as conductivity,
insulating property, or temperature dependence of such properties,
and can therefore be used suitably in a semiconductor composition.
Although factors that have made such control possible are not
definite, the Si--OH bonds or Si--O bonds contained in particle
surfaces respectively have properties of vibrating in response to
and thereby absorbing waves of different energies and the present
inventors consider that by controlling the ratio of Si--OH bonds or
the ratio of Si--OH bonds/Si--O bonds contained in the
silicon-compound-coated fine metal particles, it is possible to
control the types of different energies that are absorbed by the
respective vibrations of the Si--OH bonds or the Si--O bonds. Also,
whereas at mutual bonds, such as Si--Si, of the silicon element,
which is a metalloid, and at bonds, such as Si-M, of the silicon
element (Si) and M, which is another metal element or metalloid
element, free electrons may be considered to move freely between
atoms, at terminal portions of such bonds, in other words, at
particle surfaces, the free electrons may considered to be in an
activated state due to being in a state of not having anywhere to
move to and may be said to be in a state of being capable of
constantly giving rise to new bonds. The present inventors consider
that a metal element or a metalloid element, such as silicon, that
contains activated electrons give rise to bonds with, for example,
oxygen or the like in the surroundings, and a resulting
silicon-oxygen bond (Si--O bond) or metal-oxygen bond (M-O bond)
reacts further with another element or functional group to change
into a bond, such a silicon-oxygen bond (Si--OH bond) or a
metal-hydroxyl group bond (M-OH bond), that is most stable under
the environment in which the particles are placed. It was thus
found that because the Si--O bonds or M-O bonds and the Si--OH
bonds or M-OH bonds on the particle surfaces are in equilibrium
states, the ratio of Si--OH bonds/Si--O bonds or a ratio of M-OH
bonds/M-0 bonds can be controlled by treating the particles under a
specific environment, and because influences that these ratios have
on the properties of the particles become greater as the particles
become smaller, the properties of the silicon-compound-coated fine
metal particles can be controlled precisely by controlling the
ratio of the Si--OH bonds/Si--O bonds precisely.
[0046] In a case of using the silicon-compound-coated fine metal
particles according to the present invention as a catalyst,
suitable use in a catalyst composition is also possible because
catalytic ability can also be controlled by controlling a coating
state of the silicon-compound-coated fine metal particles other
than controlling the dispersibility as mentioned above and also,
for example, in a case of use in a liquid, since coverage is
controlled by making at least a part of the silicon compound
coating the surfaces dissolve during use such that surface-active
portions of the fine metal particles that were coated become
exposed by dissolution of the silicon compound coating and the
catalytic ability of the metal particles thus become exhibited or
improved, the catalytic activity in this process can be controlled
by controlling the ratio of Si--OH bonds or the ratio of Si--OH
bonds/Si--O bonds contained in the silicon-compound-coated fine
metal particles to control solubility or dissolution rate of the
silicon compound, coating the surfaces of the fine metal particles
at least partially, to enable control and improvement of the
properties of the catalyst. Similarly, in a case of using the
silicon-compound-coated fine metal particles according to the
present invention as a reaction material in an oxidizing agent, a
reducing agent, or the like, suitable use in a reaction composition
is also possible because, by controlling the solubility or the
dissolution rate of the silicon compound in the liquid, by which
the surfaces of the metal particles in a liquid are coated at least
partially, an intended reaction of the metal particles included in
the silicon-compound-coated fine metal particles with a reactant
can be controlled to enable improvement of reaction product yield
and selectivity.
[0047] (Configuration of Silicon-Compound-Coated Fine Metal
Particles--1)
[0048] The silicon-compound-coated fine metal particles according
to the present invention are silicon-compound-coated fine metal
particles, with which surfaces of fine metal particles are at least
partially coated with a silicon compound, and the fine metal
particles contain, as the metal, one or plurality of different
elements among metal elements and metalloid elements on the
periodic table. The metal elements in the present invention are not
specifically limited and the metal element Ag, Cu, Fe, Al, or the
like can be cited as preferable. Also, the metalloid elements in
the present invention are not specifically limited and the
metalloid element Si, Ge, As, Sb, Te, Se or the like can be cited
as preferable. In regard to the metals and metalloids, the metal
particles may be fine metal particles composed of a single metal
element or may be fine alloy particles composed of a plurality of
metal elements or fine alloy particles containing a metal element
and a metalloid element.
[0049] (Configuration of Silicon-Compound-Coated Fine Metal
Particles--2)
[0050] The metal particles in the silicon-compound-coated fine
metal particles according to the present invention are not limited
to just those composed only of a metal. The present invention can
be embodied by including a compound other than a metal to the
extent that it does not affect the present invention. For example,
the silicon-compound-coated fine metal particles can be embodied as
those with which surfaces of fine metal particles or fine alloy
particles that contain a compound other than metal are at least
partially coated with a silicon compound. Examples of the compound
other than a metal include oxides, hydroxides, nitrides, carbides,
various salts, such as nitrates, sulfates, and carbonates,
hydrates, and organic solvates.
[0051] (Configuration of Silicon-Compound-Coated Fine Metal
Particles--3)
[0052] The silicon-compound-coated fine metal particles of the
present invention are silicon-compound-coated fine metal particles,
with which the ratio of Si--OH bonds contained in the
silicon-compound-coated metal particles or the ratio of Si--OH
bonds/Si--O bonds that is the ratio of Si--OH bonds with respect to
the Si--O bonds contained in the particles is controlled. The
silicon-compound-coated fine metal particles of the present
invention thus contain at least silicon (Si) and oxygen (O). As a
method for evaluating that silicon (Si) and oxygen (O) are
contained, a method, where a transmission electron microscope (TEM)
or a scanning transmission electron microscope (STEM) is used to
observe a plurality of the particles and an energy dispersive x-ray
analysis apparatus (EDS) is used to determine an abundance ratio of
silicon with respect to elements other than silicon and presence
positions of silicon in each particle, is preferable. As an
example, a method for evaluating uniformity by specifying the
abundance ratio (molar ratio) of an element other than silicon and
silicon contained in a single silicon-compound-coated fine metal
particle and calculating an average value and a coefficient of
variation of the molar ratio in a plurality of
silicon-compound-coated fine metal particles, a method for
specifying the presence positions of silicon contained in a
silicon-compound-coated fine metal particle by mapping, or the like
can be cited. In the present invention, the silicon-compound-coated
fine metal particles are preferably those with which silicon and
oxygen are detected in vicinities of surface layers of the
silicon-compound-coated fine metal particles in STEM mapping or
line analysis. By coating the surfaces of fine metal particles with
the silicon compound, an advantage of enabling water resistance and
chemical stability, such as acid resistance and alkali resistance,
to be imparted to the fine metal particles is provided.
[0053] (Description of Si--OH Bonds and Si--O Bonds--1)
[0054] In the present invention, various properties, such as
dispersibility, of the silicon-compound-coated fine metal particles
are controlled by controlling the ratio of Si--OH bonds contained
in the silicon-compound-coated fine metal particles or the ratio of
Si--OH bonds/Si--O bonds that is the ratio of Si--OH bonds with
respect to the Si--O bonds contained in the particles. The ratio of
the Si--OH bonds or the Si--OH bonds/Si--O bonds can, for example,
be determined from FT-IR measurement results. Here, IR is an
abbreviation for infrared absorption spectroscopy. (Hereinafter
indicated simply as IR measurement.) The ratio of the Si--OH bonds
or the Si--OH bonds/Si--O bonds may be measured by a method other
than IR measurement and examples of such a method include X-ray
photoelectron spectroscopy (XPS), solid state nuclear magnetic
resonance (solid NMR), electron energy loss spectroscopy (EELS),
and the like.
[0055] (Description of Si--OH Bonds and Si--O Bonds--2)
[0056] In the present invention, the ratio of Si--OH bonds or the
ratio of Si--OH bonds/Si--O bonds contained in the
silicon-compound-coated fine metal particles is preferably obtained
by waveform separation of peaks in a wavenumber region of 750
cm.sup.-1 to 1300 cm.sup.-1 in an infrared absorption spectrum
measurement of the silicon-compound-coated fine metal particles, an
Si--OH-bond-derived peak is preferably deemed to be a peak
attributed to a peak of greatest area ratio among
Si--OH-bond-derived peaks, waveform-separated in a wavenumber
region of 850 cm.sup.-1 to 980 cm.sup.-1, and an Si--O-bond-derived
peak is preferably deemed to be a peak attributed to a peak of
greatest area ratio among Si--O-bond-derived peaks,
waveform-separated in a wavenumber region of 1000 cm.sup.-1 or more
and 1300 cm.sup.-1 or less. Usually, it is preferable to deem the
ratio of Si--OH bonds to be a ratio of an area of the peak
attributed to the Si--OH bonds with respect to a total area of
peaks obtained by waveform separation of peaks in the wavenumber
region of 750 cm.sup.-1 to 1300 cm.sup.-1, to deem the ratio of
Si--O bonds to be a ratio of an area of the peak attributed to the
Si--O bonds with respect to the total area of the peaks, and to
calculate the ratio of Si--OH bonds/Si--O bonds from the ratio of
Si--OH bonds with respect to the ratio of Si--O bonds obtained by
the waveform separation of peaks in the wavenumber region of 750
cm.sup.-1 to 1300 cm.sup.-1. That is, control of ratio is performed
at least in regard to a bond of a functional group differing from
the types of bonds described in Patent Literature 4.
[0057] (Description of Amorphous Silicon Compound)
[0058] In the present invention, the silicon compound coating the
surface of the fine metal particles at least partially preferably
contains an amorphous silicon oxide to facilitate the control of
the ratio of the Si--OH bonds or the Si--OH bonds/Si--O bonds. A
method for evaluating that the silicon compound contains an
amorphous silicon oxide is not specifically limited, and a method
for evaluating by combining a result that a peak derived from
crystalline silica (SiO.sub.2) is not seen in XRD measurement with
the confirmation of the presence of Si and O by the STEM mapping
mentioned above and the confirmation of the presence of a silicon
oxide by an infrared absorption spectrum, a method for confirming
that a crystal lattice is not observed at portions at which Si and
O are detected in TEM observation or STEM observation, or the like
can be cited.
[0059] (Method for Controlling the Ratio of Si--OH Bonds or Si--OH
Bonds/Si--O Bonds--1)
[0060] In the present invention, although a method for controlling
the ratio of the Si--OH bonds or the Si--OH bonds/Si--O bonds is
not specifically limited, it is preferable to control the ratio of
the Si--OH bonds or the Si--OH bonds/Si--O bonds by a changing
treatment of functional groups contained in the
silicon-compound-coated fine metal particles. In the functional
group changing treatment, the ratio of the Si--OH bonds or the
Si--OH bonds/Si--O bonds can be controlled by a method for
subjecting the functional groups contained in the
silicon-compound-coated fine metal particles to a conventionally
known substitution reaction, addition reaction, elimination
reaction, dehydration reaction, condensation reaction, reduction
reaction, oxidation reaction, or the like. The ratio of the Si--OH
bonds or the Si--OH bonds/Si--O bonds may be controlled to increase
or may be controlled to decrease by the functional group changing
treatment. As an example, a method can be cited where, for example,
a carboxylic acid, such as acetic anhydride, is made to act on the
Si--OH bonds contained in the silicon-compound-coated fine metal
particles to control the ratio of the Si--OH bonds or the Si--OH
bonds/Si--O bonds by esterification achieved by a
dehydration/condensation reaction, in which OH is eliminated from a
carboxyl group (--COOH) and H is eliminated from a hydroxyl group
(--OH) of an Si--OH group, and for the esterification, a method for
using a dehydrating agent, such as a mixed acid anhydride, an acid
hydride, or a carbodiimide, or other method other than the method
for using an acid anhydride may be employed. Other than the
abovementioned esterification, the ratio of Si--OH bonds or the
ratio of Si--OH bonds/Si--O bonds can also be controlled by a
method for making an alkyl halide, an aryl halide, or a heteroaryl
halide act on the Si--OH group, preferably under the presence of an
acid catalyst, to make an ether bond form between Si and a
substance, such as the abovementioned alkyl halide, by dehydration,
a method for making an isocyanate or a thioisocyanate act on the
Si--OH to make a (thio) urethane bond be formed, or the like.
[0061] In regard to a substance to be made to act on the Si--OH
bonds, a substance, containing a fluorine-containing functional
group or a hydrophilic, lipophilic, or other functional group, may
be used to control the ratio of Si--OH bonds or the ratio of Si--OH
bonds/Si--O bonds contained in the silicon-compound-coated fine
metal particles. The present invention is not limited to making
another substance or functional group act directly on the Si--OH
bonds or the Si--O bonds to form new bonds and, for example, the
ratio of Si--OH bonds or the ratio of Si--OH bonds/Si--O bonds can
also be controlled by a method for controlling the ratio of Si--OH
bonds or the ratio of Si--OH bonds/Si--O bonds by a method for
making a carbodiimide act on a carboxylic acid or the like
contained in the particles, or a method for making ethylene oxide
or the like act on the Si--OH bonds to form bonds, such as
Si--O--(CH.sub.2).sub.2--OH, or making an epihalohydrin act on the
Si--OH bonds, and so forth. Other than the above, the ratio of
Si--OH bonds or the ratio of Si--OH bonds/Si--O bonds can also be
controlled by a method for making hydrogen peroxide or ozone act on
the silicon-compound-coated fine metal particles. It is also
possible to control the ratio of Si--OH bonds or the ratio of
Si--OH bonds/Si--O bonds by using a formulation of a metal raw
material liquid or a metal precipitation solvent for precipitating
the silicon-compound-coated fine metal particles or a method for
controlling the pH or the like during precipitation of the
silicon-compound-coated fine metal particles in a liquid. Also, as
an example of the dehydration reaction, the ratio of Si--OH bonds
or the ratio of Si--OH bonds/Si--O bonds can be controlled by a
method for heat-treating the silicon-compound-coated fine metal
particles. For controlling the ratio of Si--OH bonds or the ratio
of Si--OH bonds/Si--O bonds by the method for heat-treating the
silicon-compound-coated fine metal particles, a dry-heat treatment
can be performed or heat treatment can be performed in a dispersion
state, in which the silicon-compound-coated fine metal particles
are dispersed in a dispersion medium.
[0062] (Method for Controlling the Ratio of Si--OH Bonds or Si--OH
Bonds/Si--O Bonds--2)
[0063] As the functional group changing treatment of the
silicon-compound-coated fine metal particles according to the
present invention, other than a reaction, such as dehydration, the
ratio of Si--OH bonds or Si--OH bonds/Si--O bonds can be controlled
by a reduction reaction or an oxidation reaction by treatment of
the silicon-compound-coated fine metal particles in a reducing
atmosphere or an oxidizing atmosphere. For example, the ratio of
Si--OH bonds or Si--OH bonds/Si--O bonds can be controlled by
treating a powder of the silicon-compound-coated fine metal
particles with a reducing gas, such as hydrogen, ammonia, hydrogen
sulfide, sulfur dioxide, or nitrogen monoxide, an oxidizing gas,
such as oxygen, ozone, or nitrogen dioxide, or the like inside a
furnace to change an oxidation number of Si or M contained in the
silicon-compound-coated fine metal particles, with which the
surfaces of the fine metal particles are at least partially coated
with the silicon compound. Such functional group changing
treatments, including the oxidation treatment or reduction
treatment mentioned above, may be performed in combination, for
example, in a method for performing a heat treatment and a
reduction treatment at the same time or the like.
[0064] (Method for Controlling the Ratio of Si--OH Bonds or Si--OH
Bonds/Si--O Bonds--3)
[0065] Also, as will be described later, the ratio of Si--OH bonds
or the ratio of Si--OH bonds/Si--O bonds may be controlled by
dispersing the silicon-compound-coated fine metal particles in an
intended solvent, adding a substance containing a functional group
to the dispersion liquid, and applying a treatment, such as
stirring, or the ratio of Si--OH bonds or the ratio of Si--OH
bonds/Si--O bonds may be controlled by continuing to apply the
treatment, such as stirring, as it is to the dispersion liquid
containing the silicon-compound-coated fine metal particles
precipitated by mixing the metal raw material liquid, the metal
precipitation solvent, and a silicon compound raw material liquid.
Furthermore, the control can be performed by constructing an
apparatus, in which a dispersing device and a membrane filter are
arranged in series, and changing, in performing such a method as
applying a dispersion treatment on the particles and performing
cross-flow membrane filtration to remove impurities from a slurry
containing the silicon-compound-coated fine metal particles, the
temperature of the slurry, the temperature of a washing liquid used
for cross flow, or the like. In this case, a uniform modifying
treatment can be performed on the primary particles and
particularly the surfaces of the respective primary particles of
the silicon-compound-coated fine metal particles and there is
therefore an advantage that the control of the ratio of Si--OH
bonds or the ratio of Si--OH bonds/Si--O bonds contained in the
silicon-compound-coated fine metal particles and the control of
dispersibility and other properties of the present invention can be
performed more precisely and homogeneously.
[0066] In regard to the pH adjustment for precipitating the
silicon-compound-coated fine metal particles, the adjustment may be
performed by a pH adjusting agent, such as an acidic or basic
substance, being included in at least one of various solutions and
solvents in the present invention or adjustment may be performed by
changing the flow rate when mixing a fluid containing the metal raw
material liquid with a fluid containing the metal precipitation
solvent.
[0067] The method for changing the functional groups contained in
the silicon-compound-coated fine metal particles according to the
present invention is not particularly limited. The change may be
achieved by dispersing the silicon-compound-coated fine metal
particles in an intended solvent, adding a substance containing a
functional group to the dispersion liquid, and subjecting the
dispersion liquid to a treatment such as stirring or the change may
be achieved by mixing a fluid, containing the
silicon-compound-coated fine metal particles, with a fluid,
containing a substance containing a functional group, using a
microreactor described in Patent Literature 5.
[0068] The substance containing a functional group is not
particularly limited, but is a substance containing a functional
group that can be substituted with a hydroxyl group contained in
the silicon-compound-coated fine metal particles and examples of
such a substance include acylating agents, such as acetic anhydride
and propionic anhydride; methylating agents, such as dimethyl
sulfate and dimethyl carbonate; silane coupling agents, such as
chlorotrimethylsilane and methyltrimethoxysilane; and the like.
Other than the above, for example, a fluorine-containing compound,
such as trifluoroacetic acid or trifluoromethanesulfonic acid that
is a substance containing a CF bond, which is a hydrophobic group,
or an anhydride of such substance, or a fluorine-containing silane
coupling agent, such as
triethoxy-1H,1H,2H,2H-heptadecafluorodecylsilane or
trimethoxy(3,3,3-trifluoropropyl)silane, or a fluorine compound,
such as trifluoromethane or trifluoroethane can be cited. Further,
it is also possible to control the ratio of Si--OH bonds or the
ratio of Si--OH bonds/Si--O bonds contained in
silicon-compound-coated oxide particles, for example, by a method
for making a gas, such as trifluoromethane or trifluoroethane, act
on silicon-compound-coated oxide particles as well. Specifically,
when such substances containing a functional group that can be
substituted with a hydroxyl group is used, the ratio of Si--OH
bonds can be controlled.
[0069] As mentioned above, the ratio of Si--OH bonds or the ratio
of Si--OH bonds/Si--O bonds can also be controlled by a method for
making hydrogen peroxide or ozone act on the oxide particles. The
method for making hydrogen peroxide or ozone act on the
silicon-compound-coated fine metal particles is not particularly
limited. It may be performed by dispersing the
silicon-compound-coated fine metal particles in an intended
solvent, adding hydrogen peroxide or ozone or an aqueous solution
or other solution containing these substances, and performing a
treatment, such as stirring, or it may be performed by mixing a
fluid, containing the silicon-compound-coated fine metal particles,
and a fluid, containing hydrogen peroxide or ozone, using the
microreactor described in Patent Literature 5.
[0070] The dispersion may be a liquid dispersion, in which the
silicon-compound-coated fine metal particles are dispersed in a
liquid dispersion medium, such as water, an organic solvent, or
resin, or may be a film-like dispersion prepared using a dispersion
liquid containing the silicon-compound-coated fine metal particles.
Performing heat treatment in a state of a dispersion containing the
silicon-compound-coated fine metal particles is suitable for
reducing the number of steps and for precise control of properties
because aggregation of particles can be suppressed as compared with
heat treatment in a dry state and, for example, when the
silicon-compound-coated fine metal particles of the present
invention are used in a coating film, the properties of the
silicon-compound-coated fine metal particles can be controlled by
controlling the ratio of Si--OH bonds or the ratio of Si--OH
bonds/Si--O bonds contained in the silicon-compound-coated fine
metal particles by such a method as heat treatment after the
silicon-compound-coated fine metal particles are processed into a
coating film.
[0071] Also, other than the coating film application mentioned
above, the silicon-compound-coated fine metal particles can also be
used in a composition for transparent material to be used, for
example, in a glass, film, transparent resin, or the like of a
building, by dispersing in a glass, a resin, or the like and
thereby used suitably to shield against electromagnetic waves, such
as ultraviolet rays and near-infrared rays, and can thus be used
suitably as a silicon-compound-coated fine metal composition for a
purpose of ultraviolet protection or near-infrared protection as
well. Also, as with the coating film mentioned above, the particles
are suitable for reducing the number of steps and for precise
control of properties because, as with the coating film mentioned
above, the properties of the silicon-compound-coated fine metal
particles can be controlled by controlling the ratio of Si--OH
bonds or the ratio of Si--OH bonds/Si--O bonds contained in the
silicon-compound-coated fine metal particles by performing
functional group changing treatment by heat treatment or the like
after the silicon-compound-coated fine metal particles are
dispersed in a glass, a transparent resin, or the like and
processed into a film.
[0072] In the present invention, the primary particle diameter of
the metal particles in the silicon-compound-coated fine metal
particles is preferably 1 .mu.m or less, and more preferably 1 nm
or more and 1 .mu.m or less. Also, the primary particle diameter of
the silicon-compound-coated fine metal particles that are coated is
preferably 1 .mu.m or less, and more preferably 1 nm or more and
0.5 .mu.m or less. It can be assumed that the control of the
properties of the silicon-compound-coated fine metal particles can
be performed precisely because the Si--OH bonds or the Si--O bonds
contained in the silicon-compound-coated fine metal particles are
present mainly on the particle surfaces, and therefore with the
silicon-compound-coated fine metal particles that have a primary
particle diameter of 1 .mu.m or less are thus have an increased
surface area as compared with silicon-compound-coated fine metal
particles having a primary particle diameter of more than 1 .mu.m,
influences, imparted on such properties as dispersibility of the
silicon-compound-coated fine metal particles by the control of the
ratio of Si--OH bonds or the ratio of Si--OH bonds/Si--O bonds of
the silicon-compound-coated fine metal particles, are considered to
be high. Silicon-compound-coated fine metal particles having a
primary particle diameter of 1 nm or less thus provide an advantage
of enabling predetermined properties (especially properties
suitable for use in a coating composition for purpose of use in a
coating film, a coated body, or the like, a composition for
transparent material for purpose of use in a coated body, glass,
transparent resin, or film, with which transparency is required, a
magnetic composition for purpose of use in a magnetic body, such as
a magnetic fluid, a semiconductor composition for purpose of use in
a semiconductor or the like, a conductive composition for purpose
of use as a conductive material, or a reaction composition for
purpose of use in reaction material or the like or a catalyst
composition for purpose of use in catalyst material or the like) to
be exhibited suitably by control of the ratio of Si--OH bonds or
the ratio of Si--OH bonds/Si--O bonds contained in the
silicon-compound-coated fine metal particles.
[0073] With the silicon-compound-coated fine metal particles
according to the present invention, a ratio of the average primary
particle diameter of the silicon-compound-coated fine metal
particles with respect to the average primary particle diameter of
the fine metal particles before coating with the silicon compound
is preferably 100.5% or more and 190% or less. If the coating of
the silicon compound on the fine metal particles is too thin, there
is a possibility that an effect related to the properties that the
silicon-compound-coated fine metal particles have and so forth
cannot be exhibited, and therefore, the average primary particle
diameter of the silicon-compound-coated fine metal particles is
preferably 100.5% or more of the average primary particle diameter
of the metal particles, and because when the coating is too thick
or when coarse aggregates are coated, it is difficult to control
the properties, and when the thickness of the coating exceeds 1
.mu.m, a possibility of mutual overlapping of the
Si--OH-bond-derived peaks and the Si--O-bond-derived peaks in the
IR measurement result arises, the average primary particle diameter
of the silicon-compound-coated fine metal particles is preferably
190% or less of the average primary particle diameter of the fine
metal particles. The various compositions according to the present
invention include fine metal particles with surfaces at least
partially covered with a silicon compound, that is, the
silicon-compound-coated fine metal particles per se. The
silicon-compound-coated fine metal particles according to the
present invention may be silicon-compound-coated fine metal
particles of core-shell type, with which entire surfaces of the
fine metal particles serving as cores are uniformly coated with the
silicon compound. Also, although the silicon-compound-coated fine
metal particles are preferably silicon-compound-coated fine metal
particles, with which a plurality of fine metal particles are not
aggregated and with which surfaces of single metal particles are at
least partially coated with the silicon compound, the particles may
also be silicon-compound-coated fine metal particles, with which
surfaces of aggregates, each formed by aggregation of a plurality
of fine metal particles, are at least partially coated with the
silicon compound. However in this case, the silicon-compound-coated
fine metal particles, with which the abovementioned aggregates that
exceed a certain size are coated with the silicon compound, are not
preferable in that dispersibility and other properties mentioned
above cannot be obtained readily in comparison to the
silicon-compound-coated fine metal particles, with which the
surface of single fine metal particles are at least partially
covered with the silicon compound. Here, the aggregates exceeding a
certain size refer, for example, to aggregates that exceed 1 .mu.m
in size. Also, the particle diameter of the silicon-compound-coated
fine metal particles, with which surfaces of aggregates, each
formed by aggregation of a plurality of fine metal particles, are
at least partially coated with the silicon compound, is preferably
100.5% or more and 190% or less of the diameter of the aggregates.
Here, the diameter of the aggregates is deemed to be the distance
between the maximum outer circumferences of the aggregates.
[0074] (Method for Producing Silicon-Compound-Coated Fine Metal
Particles: Preferable Method)
[0075] As an example of a method for producing the
silicon-compound-coated fine metal particles according to the
present invention, it is preferred to use a method for producing
the silicon-compound-coated fine metal particles by preparing a
metal raw material liquid, containing at least a raw material of
the metal particles that are to be coated with the silicon
compound, and a metal precipitation solvent, containing at least a
metal precipitation substance for precipitating the metal
particles, precipitating the fine metal particles by a method of
reaction, crystallization, separation, co-precipitation, or the
like in a mixture fluid, in which the metal raw material liquid and
the metal precipitation solvent are mixed, and mixing the mixture
fluid, containing the precipitated fine metal particles, with a
silicon compound raw material liquid, containing at least a raw
material of the silicon compound, to coat the surfaces of the fine
metal particles at least partially with the silicon compound. Also,
in a case where the fine metal particles are fine alloy particles
and the purpose is to prepare silicon-compound-coated fine alloy
particles, the plurality of different metal elements or metalloid
elements contained in the fine metal particles may be contained
together in the metal raw material liquid or may be contained
respectively in the metal raw material liquid and the metal
precipitation solvent, or may be contained in both the metal raw
material liquid and the metal precipitation solvent or the silicon
compound raw material liquid.
[0076] The raw material of the silicon-compound-coated fine metal
particles in the present invention are not limited in particular.
Any raw material that can be formed into the
silicon-compound-coated fine metal particles by a method of
reaction, crystallization, separation, co-precipitation, or the
like may be applicable. Also, with the present invention, a
compound of a metal or a metalloid is referred to generally as a
compound. The compound is not limited in particular and to give an
example, a salt, oxide, hydroxide, hydroxide oxide, nitride,
carbide, complex, organic salt, organic complex, or organic
compound of a metal or a metalloid that contains a metal element or
a metalloid element, or a hydrate, organic solvate, or the like of
such a compound can be cited. An elementary metal or metalloid may
also be used. The salt of a metal or metalloid is not limited in
particular and a nitrate, nitrite, sulfate, sulfite, carbonate,
formate, acetate, phosphate, phosphite, hypophosphite, chloride,
oxy salt, or acetylacetonate salt of a metal or a metalloid, or a
hydrate, organic solvate, or the like of such a salt can be cited,
and as the organic compound, an alkoxide or the like of a metal or
a metalloid can be cited. These metal or metalloid compounds may be
used alone or may be used as a mixture of a plurality or more of
the compounds. In the present invention, if the metal constituting
the silicon-compound-coated fine metal particles is a plurality of
different metal elements or metalloid elements and if the main
metal element is M1 and a subsidiary metal element is M2, a molar
ratio (M2/M1) of M2 with respect to M1 is preferably 0.01 or more
and 1.00 or less.
[0077] Also, as the raw material of the silicon compound according
to the present invention, an oxide or hydroxide of silicon as well
as a compound, such as a salt or alkoxide of silicon, or a hydrate
of such a compound can be cited. Although not limited in
particular, sodium silicate or other silicate,
phenyltrimethoxysilane, methyltrimethoxysilane,
methyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane,
3-trifluoropropyltrimethoxysilane,
methacryloxypropyltriethoxysilane, tetramethoxysilane (TMOS),
tetraethoxysilane (TEOS), ethyl silicate 40 or other oligomer
condensate of TEOS, tetraisopropylsilane, tetrapropoxysilane,
tetraisobutoxysilane, tetrabutoxysilane, or other similar substance
can be cited. Further as the raw material of the silicon compound,
any of other siloxane compounds, bis(triethoxysilyl)methane,
1,9-bis(triethoxysilyl)nonane, diethoxydichlorosilane,
triethoxychlorosilane, or the like may be used.
[0078] Also, when the raw material of the fine metal particles or
the silicon compound for coating is a solid, each raw material is
preferably used in a molten state or state of being dissolved or
mixed (including a state of being molecularly dispersed) in a
solvent described later. Even when each raw material is a liquid or
a gas, it is preferably used in a state of being dissolved or mixed
(including a state of being molecularly dispersed) in a solvent
described below.
[0079] The metal precipitation substance is not particularly
limited as long as it is a substance capable of making the raw
material of the silicon-compound-coated fine metal particles,
contained in the metal raw material liquid, precipitate as the
silicon-compound-coated fine metal particles, and, for example, a
reducing agent, capable of reducing ions of the metal or metalloid
contained in the metal raw material liquid, is preferably used. The
reducing agent is not limited in particular, and all reducing
agents capable of reducing the metal element or metalloid element
constituting the silicon-compound-coated fine metal particles can
be used. As an example, a hydride-based reducing agent, such as
sodium borohydride or lithium borohydride, an aldehyde, such as
formalin or an aldehyde, a sulfite, a carboxylic acid, such as
formic acid, oxalic acid, succinic acid, ascorbic acid, or citric
acid, a lactone, a monoalcohol, such as an aliphatic monoalcohol,
such as methanol, ethanol butanol, isopropyl alcohol, or octanol,
or an alicyclic monoalcohol, such as turpineol, an aliphatic diol,
such as ethylene glycol, propylene glycol, diethylene glycol,
dipropylene glycol, triethylene glycol, or tetraethylene glycol, a
polyol, such as glycerin or trimethylolpropane, a polyether, such
as polyethylene glycol or polypropylene glycol, an alkanolamine,
such as diethanolamine or monoethanolamine, a phenol, such as
hydroquinone, resorcinol, or aminophenol, a saccharide, such as
glucose or fructose, sodium citrate, hypochlorous acid or a salt
thereof, ions of a transition metal (ions of titanium, iron, or the
like), a hydrazine, an amine, such as triethylamine,
triethanolamine, dimethylaminoethanol, octylamine, or
dimethylaminoborane, a pyrrolidone (polyvinylpyrrolidone,
1-vinyl-2-pyrrolidone, methylpyrollidone), or the like can be
cited, and a reducing gas, such as hydrogen gas or ammonia gas, may
also be used.
[0080] Also, the metal raw material liquid and the metal
precipitation solvent may contain an acidic substance or a basic
substance. Examples of the basic substance include metal
hydroxides, such as sodium hydroxide and potassium hydroxide, metal
alkoxides, such as sodium methoxide and sodium isopropoxide, amine
compounds, such as triethylamine, diethylaminoethanol, and
diethylamine, ammonia, and the like.
[0081] Examples of the acidic substance include inorganic acids,
such as aqua regia, hydrochloric acid, nitric acid, fuming nitric
acid, sulfuric acid, and fuming sulfuric acid, and organic acids,
such as formic acid, acetic acid, chloroacetic acid, dichloroacetic
acid, oxalic acid, trifluoroacetic acid, trichloroacetic acid, and
citric acid. The basic substance and the acidic substance can also
be used for precipitating the silicon-compound-coated metal
particles or the compound for coating.
[0082] (Solvent)
[0083] Examples of the solvent used as the solvent for the metal
raw material liquid, the metal precipitation solvent, or the
silicon raw material liquid include water, an organic solvent, and
a mixed solvent composed of a plurality of the same. Examples of
the water include tap water, ion-exchanged water, pure water,
ultrapure water, RO water (reverse osmosis water), and the like and
examples of the organic solvent include alcohol compound solvents,
amide compound solvents, ketone compound solvents, ether compound
solvents, aromatic compound solvents, carbon disulfide, aliphatic
compound solvents, nitrile compound solvents, sulfoxide compound
solvents, halogen compound solvents, ester compound solvents, ionic
liquids, carboxylic acid compounds, sulfonic acid compounds, and
the like. The above solvents may be used alone or may be used as a
mixture of a plurality of the solvents. Examples of the alcohol
compound solvents include monohydric alcohols, such as methanol and
ethanol, polyols, such as ethylene glycol and propylene glycol, and
the like.
[0084] (Dispersants, Etc.)
[0085] Various dispersants and surfactants may be used according to
purpose and necessity in a range of not adversely affecting the
preparation of the silicon-compound-coated fine metal particles
according to the present invention. The dispersant or surfactant is
not limited in particular and any of various generally used,
commercially available products, manufactured goods, newly
synthesized products, or the like can be used. For example, anionic
surfactants, cationic surfactants, nonionic surfactants, and
various polymers and other dispersants, and the like can be cited.
These may be used alone or in combination of two or more thereof.
The surfactant and dispersant may be contained in at least one of
either of the metal raw material liquid and the metal precipitation
solvent. Also, the surfactant and the dispersant may be contained
in another fluid different from the metal raw material liquid and
the metal precipitation solvent.
[0086] (Method for Producing Silicon-Compound-Coated Fine Metal
Particles: Outline of Method)
[0087] In the step of coating the surfaces of the fine metal
particles at least partially with the silicon compound, it is
preferable for the fine metal particles to be coated with the
silicon compound before the metal particles aggregate. In mixing
the silicon compound raw material liquid into the fluid containing
the fine metal particles, it is important as to how the silicon
compound raw material liquid can be charged and the silicon
compound be precipitated on the surfaces of the fine metal
particles at a rate faster than that at which aggregation occurs
after the fine metal particles precipitate. Further, by charging
the silicon compound raw material liquid into the fluid containing
the fine metal particles, the pH of the fluid containing the fine
metal particles and the concentration of the silicon compound raw
material change gradually, and if the silicon compound for coating
the surfaces of the particles precipitates after circumstances
where the particles are readily dispersed change to circumstances
where aggregation occurs readily, there is a possibility that it
becomes difficult to achieve coating before aggregation occurs to a
degree such that the properties of the present invention cannot be
exhibited. It is preferable to make the silicon compound raw
material contained in the silicon compound raw material liquid act
immediately after the fine metal particles precipitate. It is
preferable to obtain the silicon-compound-coated fine metal
particles by a method for making the fine metal particles
precipitate and coating the silicon compound on the surfaces of the
fine metal particles continuously subsequent to the precipitation
of the fine metal particles between processing surfaces that are
capable of approaching and separating from each other and rotate
relative to each other as described in Patent Literature 5. An
advantage of enabling the silicon-compound-coated fine metal
particles of the present invention to be prepared and the control
of the ratio of Si--OH bonds or the ratio of Si--OH bonds/Si--O
bonds and the control of the properties of the
silicon-compound-coated metal particles thereby to be performed
with precision by changing the temperature, the pH, and the
formulation conditions in the process of obtaining the
silicon-compound-coated fine metal particles is provided. By
setting the temperature in the process of obtaining the
silicon-compound-coated fine metal particles to a certain
temperature or higher, it is possible to prepare
silicon-compound-coated fine metal particles, each having a hollow
layer between the fine metal particle and the coating layer of the
silicon compound in the silicon-compound-coated fine metal
particle. Use is made of a shrinkage rate of the silicon compound
being lower than a shrinkage rate of the fine metal particles in
the silicon-compound-coated fine metal particles by precipitating
the fine metal particles under an environment of the certain
temperature or higher, then coating the particle surfaces with the
silicon compound at approximately the same temperature, and
thereafter cooling to a low temperature, such as room temperature.
In the present invention, the temperature for obtaining the
silicon-compound-coated metal particles having a hollow layer is
preferably 150.degree. C. or more and more preferably 200.degree.
C. or more.
[0088] (Method for Producing Silicon-Compound-Coated Fine Metal
Particles: Apparatus)
[0089] Examples of the method for producing the
silicon-compound-coated fine metal particles according to the
present invention include methods of preparing the
silicon-compound-coated fine metal particles and so forth by using
a microreactor, performing a reaction in a dilute system inside a
batch vessel, or the like. Also, the apparatus and the method as
described in Publication of JP 2009-112892, which are proposed by
the applicant of the present application, may be used to prepare
the silicon-compound-coated fine metal particles. The apparatus
described in Publication of JP 2009-112892 has a stirring tank,
having an inner circumferential surface with a circular cross
section, and an stirring tool, installed with there being a slight
gap from the inner circumferential surface of the stirring tank,
the stirring tank includes at least two fluid inlets and at least
one fluid outlet, a first fluid to be processed, which, among
fluids to be processed, contains one reactant, is introduced into
the stirring tank from one of the fluid inlets, a second fluid to
be processed, containing one reactant different from the above
reactant, is introduced into the stirring tank from the other one
of the fluid inlets by a flow path different from that of the first
fluid to be processed, at least one of either of the stirring tank
and the stirring tool rotates at a high speed with respect to the
other, thereby bringing the fluids to be processed into a thin film
state, and in this thin film, at least the reactants contained in
the first fluid to be processed and the second fluid to be
processed are made to react with each other, and it is stated that,
in order to introduce three or more fluids to be processed into the
stirring tank, three or more introduction pipes may be provided as
illustrated in FIG. 4 and FIG. 5 of the publication. Also, examples
of the microreactor described above include apparatuses of the same
principle as fluid treatment apparatuses described in Patent
Literature 5.
[0090] As a method for producing the silicon-compound-coated fine
metal particles of the present invention that differs from the
above method, a method for treating fine particles of a substance,
capable of being a precursor of the metal contained in the fine
metal particles, in a reducing atmosphere can be cited.
Specifically, the method is one where silicon-compound-coated fine
precursor particles, with which surfaces of fine particles
containing the precursor are at least partially coated with the
silicon compound, or silicon-doped fine precursor particles, with
which fine particles containing the precursor are doped with
silicon, are prepared and the silicon-compound-coated fine
precursor particles or the silicon-doped fine precursor particles
are treated in the reducing atmosphere. As the precursor, an oxide,
a hydroxide, a nitride, a carbide, any of various salts, such as a
nitrate, sulfate, or carbonate, a hydrate, or an organic solvate
containing a metal element or a metalloid element that constitutes
the fine metal particles can be cited. For example, by heat
treating the silicon-compound-coated fine precursor particles, such
as silicon-compound-coated iron oxide particles, in a hydrogen
atmosphere, which is a reducing atmosphere, reduction to
silicon-compound-coated iron particles can be performed. Also, even
in a case where, by treating the silicon-compound-coated fine
precursor particles in the reducing atmosphere, the silicon
compound is also reduced all the way to silicon, conversion to a
silicon oxide or other silicon compound is possible by treating in
air or other air atmosphere and therefore the
silicon-compound-coated fine metal particles can be obtained in the
same manner as the above. By thus treating the
silicon-compound-coated fine precursor particles, containing the
precursor to the fine metal particles, in the reducing atmosphere,
an advantage is provided in that not only is it possible to perform
the production of the silicon-compound-coated fine metal particles
and the ratio of Si--OH bonds or the ratio of Si--OH bonds/Si--O
bonds at practically the same time but it is also possible to
perform the ratio of Si--OH bonds or the ratio of Si--OH
bonds/Si--O bonds more precisely.
[0091] Also, the silicon-compound-coated fine metal particles
according to the present invention can also be obtained by treating
the silicon-doped fine precursor particles, with which silicon is
contained in the precursor, in the reducing atmosphere. For
example, first, by heat treating silicon-doped iron oxide
particles, which are silicon-doped precursor particles, under the
reducing atmosphere, both silicon and iron are reduced and
silicon-iron alloy particles can be obtained. Next, by treating the
obtained silicon-iron alloy particles in an oxidizing atmosphere,
such as air, and oxidizing the silicon, contained in surfaces of
the silicon-iron alloy particles, to a silicon oxide or other
silicon compound, the silicon-compound-coated fine metal particles,
such as silicon-compound-coated iron particles or
silicon-compound-coated silicon-iron alloy particles, can be
prepared.
[0092] Also, the present inventors have found that, by the heat
treatment, a change occurs where the silicon contained in the metal
particles or the oxide or other precursor particles migrates from
inner sides to exteriors of the particles. It has been found that
even in a case where particles are fused to each other, a state can
be realized where silicon or a silicon compound is decreased to a
state of not being contained at fused portions between particles,
and surfaces of the particles, which, due to fusion, have increased
in particle diameter in comparison to before treatment, can be put
in a state of being coated with the silicon compound. With the
silicon-compound-coated fine metal particles, which are prepared
using these methods and with which silicon is contained in
interiors of the fine metal particles at least before the
application of heat treatment and with which, by the application of
heat treatment, the silicon have been made to migrate from the
interiors toward outer circumferences of the fine metal particles
in comparison to before the application of heat treatment, an
advantage is provided in that the reduction or control of particle
diameter of the precursor particles and the control of the ratio of
Si--OH bonds or the ratio of Si--OH bonds/Si--O bonds can
respectively be performed at the same time. However, the present
invention is not limited to performing the reduction and the
control of the ratio of Si--OH bonds or the ratio of Si--OH
bonds/Si--O bonds at the same time. Also, for example, in a case of
using the silicon-compound-coated fine metal particles according to
the present invention in a wiring material or the like that is a
conductive material, a conductive wiring can be formed of the metal
element contained in the silicon-compound-coated fine metal
particles and, at the same time, an outer circumferential part of
the wiring can be put in a state of being coated by the silicon
compound, thus providing an advantage of enabling the metal,
forming the wiring, to be protected from moisture and protected
from oxidation by the silicon compound at the outer circumferential
part of the wiring. With the present invention, the reduction
treatment of the silicon-compound-coated fine precursor particles
or the silicon-doped fine precursor particles may be performed by a
dry method or may be performed by a wet method.
[0093] In the case of obtaining the silicon-compound-coated fine
metal particles by reduction of the silicon-compound-coated fine
precursor particles or the silicon-doped precursor particles, it is
preferable for a particle diameter of the silicon-compound-coated
fine precursor particles to be 100 nm or less. By the particle
diameter being 100 nm or less, uniform reduction treatment to the
silicon-compound-coated fine metal particles is made possible,
providing not only the advantage of enabling the control of the
ratio of Si--OH bonds or the ratio of Si--OH bonds/Si--O bonds to
be performed at the same time but also providing an advantage of
enabling fine metal particles to be produced by reduction even with
a base metal, which conventionally could not be reduced readily
except by a method, such as electroreduction using a large amount
of electricity or other energy. A method for producing the
silicon-compound-coated precursor particles is not limited in
particular, and, as with the silicon-compound-coated fine metal
particles, a preparation method using the apparatus described in
Patent Literature 5 may be performed or fine precursor particles
may be prepared using a bead mill or other pulverization method or
the like and, after the preparation, a treatment of coating the
silicon compound on the precursor particles inside a reaction
vessel or using above-described the microreactor or the like may be
performed.
[0094] (Correspondence Relationship to Priority Claim
Applications)
[0095] The present inventors found that dispersibility and other
properties of silicon-compound-coated fine metal particles can be
controlled by controlling the ratio of Si--OH bonds or the ratio of
Si--OH bonds/Si--O bonds contained in the silicon-compound-coated
fine metal particles and have thereby completed the present
invention. Coating of a silicon compound on surfaces of various
fine particles and obtaining of silicon-compound-coated fine metal
oxide particles, which can be a precursor to
silicon-compound-coated fine metal particles and with which the
silicon compound is a silicon oxide, are also disclosed in Japanese
Patent Application No. 2016-111346, which is a basic application of
the present application, and the inventors found that, with these
particles, reduction all the way to a metal can be performed in a
reducing atmosphere. The present inventors further found that by
controlling the Si--OH bonds contained in the
silicon-compound-coated fine metal particles in a specific
atmosphere as disclosed in PCT/JP2016/83001, which is another basic
application of the present application, dispersibility and other
properties of the silicon-compound-coated fine metal particles can
be controlled.
EXAMPLES
[0096] Hereinafter, the present invention will be described in more
detail with reference to Examples, but the present invention is not
limited to only these Examples. Pure water used in the Examples
below was of a conductivity of 0.84 .mu.S/cm (measurement
temperature: 25.degree. C.), unless otherwise noted.
[0097] (Preparation of Samples for TEM Observation and Preparation
of Samples for STEM Observation)
[0098] Silicon-compound-coated fine metal particles obtained in the
Examples were dispersed in a dispersion medium, the obtained
dispersion liquid was dropped on a collodion membrane and dried to
prepare a sample for TEM observation or a sample for STEM
observation.
[0099] (Transmission Electron Microscope and Energy Dispersive
X-Ray Analysis Apparatus: TEM-EDS Analysis)
[0100] For observation and quantitative analysis of the
silicon-compound-coated fine metal particles by TEM-EDS analysis, a
transmission electron microscope JEM-2100 (manufactured by JEOL
Ltd.) equipped with an energy dispersive X-ray analyzer JED-2300
(manufactured by JEOL Ltd.) was used. For observation, conditions
were an acceleration voltage of 80 kV and a magnification of
.times.25,000 or more. The particle diameter was calculated from
the distance between the maximum outer circumferences of
silicon-compound-coated fine metal particles observed by TEM, and
then the average value (average primary particle diameter) of the
results of measuring the particle diameters of 100 particles was
calculated. The molar ratio of the elemental components that
constitute the silicon-compound-coated fine metal particles was
calculated by TEM-EDS, and then the average value of the results of
calculating the molar ratio for 10 or more particles was
calculated.
[0101] (Scanning Transmission Electron Microscope and Energy
Dispersive X-Ray Analysis Apparatus: STEM-EDS Analysis)
[0102] For the mapping and quantification of elements contained in
the silicon-compound-coated fine metal particles by STEM-EDS
analysis, an atomic resolution analytical electron microscope
JEM-ARM 200F (manufactured by JEOL Ltd.) equipped with an energy
dispersive X-ray analyzer Centurio (manufactured by JEOL Ltd.) was
used. Analysis was performed upon setting the observation
conditions to an acceleration voltage of 80 kV, a magnification of
.times.50,000 or more, and a beam size of 0.2 nm in diameter.
[0103] (X-Ray Diffraction Measurement)
[0104] For X-ray diffraction (XRD) measurement, a powder X-ray
diffractometer EMPYREAN (manufactured by PANalytical Division,
Spectris Co., Ltd.) was used. Measurement conditions were as
follows: a measurement range of 10 to 100 [.degree.2.theta.], a Cu
anticathode, a tube voltage of 45 kV, a tube current of 40 mA, and
a scan rate of 0.3 degrees per minute. XRD measurement was carried
out on a dried powder of the silicon-compound-coated fine metal
particles obtained in each Example.
[0105] (FT-IR Measurement)
[0106] FT-IR measurement was carried out using a Fourier transform
infrared spectrophotometer FT/IR-6600 (manufactured by JASCO
Corporation). The measurement conditions were a resolution of 4.0
cm.sup.-1 and a number of times of accumulation of 1024 using an
ATR method under a nitrogen atmosphere. Waveform separation of
peaks at wavenumbers of 750 cm.sup.-1 to 1350 cm.sup.-1 in the IR
spectrum was performed using the spectral analysis program attached
to the control software of FT/IR-6600 mentioned above to give a
residual square sum of 0.01 or less. Measurement was carried out
using the dried powder of silicon-compound-coated fine metal
particles obtained in the Examples.
[0107] (Particle Size Distribution Measurement)
[0108] For particle size distribution measurement, a particle size
analyzer, UPA-UT151 (made by NIKKISO), was used. As measurement
conditions, the dispersion medium, in which the
silicon-compound-coated fine metal obtained in each Example was
dispersed, was used as a measurement solvent, and as a particle
refractive index and density, numerical values of the main metal
element or metalloid element constituting the metal fine particles
in the silicon-compound-coated fine metal particles obtained in
each Example were used.
Example 1
[0109] With Example 1, silicon-compound-coated fine metal particles
were prepared using an apparatus of the principles described in
Patent Literature 5 and examples of controlling dispersibility in
various dispersion media by controlling the ratio of Si--OH bonds
or the ratio of Si--OH bonds/Si--O bonds contained in the
silicon-compound-coated fine metal particles are illustrated. Using
a high-speed rotation-type dispersion emulsifier CLEARMIX (product
name: CLM-2.2S, manufactured by M Technique Co., Ltd.), a metal raw
material liquid (liquid A), a metal precipitation solvent (liquid
B), and a silicon compound raw material liquid (liquid C) were
prepared. Specifically, based on the formulation of the metal raw
material liquid indicated for Example 1 in Table 1, the respective
ingredients of the metal raw material liquid were stirred and
homogeneously mixed together at a preparation temperature of
50.degree. C. for 30 minutes using CLEARMIX at a rotor rotational
speed of 20,000 rpm to prepare the metal raw material liquid. Also,
based on the formulation of the metal precipitation solvent
indicated for Example 1 in Table 2, the respective ingredients of
the metal precipitation solvent were stirred and homogeneously
mixed together at a preparation temperature of 25.degree. C. for 30
minutes, using CLEARMIX at a rotor rotational speed of 8,000 rpm to
prepare the metal precipitation solvent. Furthermore, based on the
formulation of the silicon compound raw material liquid indicated
for Example 1 in Table 3, the respective ingredients of the silicon
compound raw material liquid were stirred and homogeneously mixed
together at a preparation temperature of 20.degree. C. for 10
minutes using CLEARMIX at a rotor rotational speed of 6,000 rpm to
prepare the silicon compound raw material liquid. Regarding the
substances indicated by chemical formulas and abbreviations
indicated in Table 1 to Table 3, as MeOH, methanol (manufactured by
Mitsubishi Chemical Corporation) was used, as EG, ethylene glycol
(manufactured by Kishida Chemical Co., Ltd.) was used, as KOH,
potassium hydroxide (manufactured by Nippon Soda Co., Ltd.) was
used, as NaOH, sodium hydroxide (manufactured by KANTO CHEMICAL
CO., INC.) was used, as TEOS, tetraethyl orthosilicate
(manufactured by Wako Pure Chemical Industries, Ltd.) was used, as
AgNO.sub.3, silver nitrate (manufactured by KANTO CHEMICAL CO.,
INC.) was used, as NaBH.sub.4, sodium tetrahydroborate
(manufactured by Wako Pure Chemical Industries, Ltd.) was used, as
HMH, hydrazine monohydrate (manufactured by KANTO CHEMICAL CO.,
INC.) was used, as PVP, polyvinylpyrrolidone K=30 (manufactured by
KANTO CHEMICAL CO., INC.) was used, as DMAE, 2-dimethylaminoethanol
(manufactured by KANTO CHEMICAL CO., INC.) was used, and as
H.sub.2SO.sub.4, concentrated sulfuric acid (manufactured by
Kishida Chemical Co., Ltd.) was used.
[0110] Subsequently, the prepared metal raw material liquid, metal
precipitation solvent, and silicon compound raw material liquid
were mixed together using a fluid treatment apparatus described in
Patent Literature 5 of the present applicant. Here, the fluid
treatment apparatus described in Patent Literature 5 is one
described in FIG. 1(B) of the literature and that having a
concentric circular annular shape, with which openings d20 and d30
of second and third introduction portions surround an opening at
the center of a processing surface 2 that is a disk formed in a
ring shape, was used. In particular, as a liquid A, the metal raw
material liquid or the metal precipitation solvent was introduced
from the first introduction portion d1 into between the processing
surfaces 1 and 2, and while driving a processing portion 10 at a
rotational speed of 1,130 rpm, the other of the metal raw material
liquid or the metal precipitation solvent, differing from the
liquid fed as the liquid A, was introduced as a liquid B from the
second introduction portion d2 into between the processing surfaces
1 and 2, and the metal raw material liquid and the metal
precipitation solvent were mixed in a thin film fluid to
precipitate fine silver particles, which are to be cores, between
the processing surfaces 1 and 2. Then, as a liquid C, the silicon
compound raw material liquid was introduced from a third
introduction portion d3 into between the processing surfaces 1 and
2 and mixed with the mixture fluid, containing the fine silver
particles, which are to be the cores, in the thin film fluid. A
silicon compound was precipitated on the surfaces of the fine
silver particles, which are to be the cores, and then a discharged
liquid, containing the silicon-compound-coated fine silver
particles (hereinafter referred to as a silicon-compound-coated
fine silver particle dispersion liquid), was discharged from
between the processing surfaces 1 and 2 of the fluid treatment
apparatus. The discharged silicon-compound-coated fine silver
particle dispersion liquid was collected in a beaker b through a
vessel v.
[0111] Table 4 shows operating conditions of the fluid treatment
apparatus, the Si/M molar ratios (Si/Ag in the case of Example 1)
calculated from the TEM-EDS analysis calculated from the TEM
observation results of the obtained silicon-compound-coated fine
silver particles, and calculated values calculated from the
formulations and introduction flow rates of the liquids A, liquids
B, and liquids C. Introduction temperatures (liquid feed
temperatures) and introduction pressures (liquid feed pressures) of
the liquids A, liquids B, and liquids C shown in Table 4 were
measured using thermometers and pressure gauges installed inside
sealed introduction passages (first introduction portion d1, second
introduction portion d2, and third introduction port d3) in
communication with an interval between processing surfaces 1 and 2,
and the introduction temperature of each liquid A shown in Table 2
is the actual temperature of the liquid A under the introduction
pressure in the first introduction portion d1, the introduction
temperature of each liquid B is likewise the actual temperature of
the liquid B under the introduction pressure in the second
introduction portion d2, and the introduction temperature of each
liquid C is likewise the actual temperature of the liquid C under
the introduction pressure in the third introduction portion d3.
[0112] The measurement of pH was performed using a pH meter of type
D-51 made by HORIBA, Ltd. Before the introduction of a liquid A, a
liquid B, and a liquid C into the fluid treatment apparatus, the pH
vales of these liquids were measured at room temperature. Also, it
is difficult to measure the pH of the mixed fluid immediately after
mixing the metal raw material liquid and the metal precipitation
solvent and the pH immediately after mixing the fluid containing
the fine silver particles, which are to be the cores, and the
silicon compound raw material liquid, and thus the pH of the
silicon-compound-coated fine silver particle dispersion liquid that
was discharged from the apparatus and then collected into the
beaker b was measured at room temperature.
[0113] From the silicon-compound-coated fine silver particle
dispersion liquid discharged from the fluid treatment apparatus and
then collected into the beaker b, a dried powder and a wet cake
sample were prepared. The preparation method was carried out
according to a conventional method of this type of treatment, and
the discharged silicon-compound-coated fine silver particle
dispersion liquid was collected, the silicon-compound-coated fine
silver particles were made to settle, a resulting supernatant was
removed, the settled particles were subsequently subjected
repeatedly to washing with 100 parts by weight of pure water and
settling and repeatedly washed until a conductivity of a wash
liquid containing the silicon-compound-coated fine silver particles
became 10 .mu.S/cm or less, and a part of a wet cake of the finally
obtained silicon-compound-coated fine silver particles was dried at
25.degree. C. under -0.10 MPaG for 20 hours to give a dried powder.
The remainder was taken as a wet cake sample.
TABLE-US-00001 TABLE 1 Formulation of the 1st fluid (Liquid A:
metal raw material liquid) Formulation pH Raw [wt %] Raw [wt %] pH
[.degree. C.] material material
TABLE-US-00002 TABLE 2 Example 1-1 AgNO.sub.3 0.150 Pure water
99.850 4.92 14.4 1-2 AgNO.sub.3 0.150 Pure water 99.850 4.92 14.4
1-3 AgNO3 0.150 Pure water 99.850 4.92 14.4 1-4 AgNO.sub.3 0.150
Pure water 99.850 4.92 14.4 1-5 AgNO.sub.3 0.150 Pure water 99.850
4.92 14.4 1-6 AgNO.sub.3 0.150 Pure water 99.850 4.92 14.4 1-7
AgNO.sub.3 0.038 EG 99.962 3.28 21.1 1-8 AgNO.sub.3 0.038 EG 99.962
3.28 21.1 1-9 AgNO.sub.3 0.038 EG 99.962 3.28 21.1
TABLE-US-00003 TABLE 3 Formulation of the 2nd fluid (Liquid B:
metal precipitation solvent) Formulation Raw Raw Raw Raw Raw Raw pH
material [wt %] material [wt %] material [wt %] material [wt %]
material [wt %] material [wt %] pH [.degree. C.] Example 1-1
NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000
>14 -- water 1-2 NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 --
0.000 -- 0.000 -- 0.000 >14 -- water 1-3 NaBH.sub.4 0.650 NaOH
1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000 >14 -- water 1-4
NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000
>14 -- water 1-5 NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 --
0.000 -- 0.000 -- 0.000 >14 -- water 1-6 NaBH.sub.4 0.650 NaOH
1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000 >14 -- water 1-7
HMH 20.00 PVP 9.75 DMAE 5.00 KOH 2.55 Pure 7.45 EG 55.25 >14 --
water 1-8 HMH 20.00 PVP 9.75 DMAE 5.00 KOH 2.55 Pure 7.45 EG 55.25
>14 -- water 1-9 HMH 20.00 PVP 9.75 DMAE 5.00 KOH 2.55 Pure 7.45
EG 55.25 >14 -- water
TABLE-US-00004 TABLE 4 Formulation of the 3rd fluid (Liquid C:
silicon compound raw material liquid) Formulation Raw Raw Raw pH
material [wt %] material [wt %] material [wt %] pH [.degree. C.]
Example 1-1 H.sub.2SO.sub.4 0.3100 TEOS 0.1300 MeOH 99.5600 1.75
14.4 1-2 H.sub.2SO.sub.4 0.3100 TEOS 0.1300 MeOH 99.5600 1.75 14.4
1-3 H.sub.2SO.sub.4 0.3100 TEOS 0.1300 MeOH 99.5600 1.75 14.4 1-4
H.sub.2SO.sub.4 0.4320 TEOS 0.1300 MeOH 99.4380 0.26 13.6 1-5
H.sub.2SO.sub.4 0.2340 TEOS 0.1300 MeOH 99.6360 1.89 14.3 1-6
H.sub.2SO.sub.4 0.0560 TEOS 0.1300 MeOH 99.8140 2.84 15.1 1-7 MeOH
1.2300 TEOS 0.0279 EG 98.7421 3.46 23.3 1-8 MeOH 1.2300 TEOS 0.0279
EG 98.7421 3.46 23.3 1-9 MeOH 1.2300 TEOS 0.0279 EG 98.7421 3.46
23.3
TABLE-US-00005 Introduction Introduction Introduction flow rate
temperature pressure (liquid feed (liquid feed (liquid feed
Discharged (Si/M) flow rate) temperature) pressure) liquid [molar
ratio] [ml/min] [.degree. C.] [MPaG] Temper- [Calculated Liquid
Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid ature
value] [EDS] A B C A B C A B C pH [.degree. C.] Si M Si M Example
1-1 500 30 85 19 17 18 0.109 0.20 0.20 9.56 24.3 10.7 89.3 10.8
89.2 1-2 500 30 85 40 38 39 0.112 0.20 0.20 9.61 23.9 10.7 89.3
10.6 89.4 1-3 500 30 85 61 62 59 0.114 0.20 0.20 9.59 24.1 10.7
89.3 10.8 89.2 1-4 500 30 85 19 17 18 0.121 0.20 0.20 7.86 23.8
10.7 89.3 10.8 89.2 1-5 500 30 85 20 18 17 0.121 0.20 0.20 11.34
24.2 10.7 89.3 10.6 89.4 1-6 500 30 85 19 18 17 0.112 0.20 0.20
13.14 23.7 10.7 89.3 10.8 89.2 1-7 500 50 100 151 87 113 0.118 0.20
0.20 11.75 32.5 10.7 89.3 10.9 89.1 1-8 500 50 100 189 89 114 0.116
0.20 0.20 11.48 28.6 10.7 89.3 10.6 89.4 1-9 500 50 100 234 89 113
0.114 0.20 0.20 11.65 29.0 10.7 89.3 10.5 89.5
[0114] With Example 1-1 to Example 1-3, the treatment temperature
in the process of precipitating the fine metal particles and making
the fluid containing the silicon compound (silicon compound raw
material liquid) act on the fine metal particles was changed for a
purpose of changing the ratio of Si--OH bonds or the ratio of
Si--OH bonds/Si--O bonds. With Example 1-4 to Example 1-6, the pH
in the process of precipitating the metal particles and making the
fluid containing the silicon compound act on the fine metal
particles was changed by changing the concentration of sulfuric
acid contained in the fluid containing the silicon compound with
respect to that of Example 1-1. With Example 1-7 to Example 1-9,
the formulations of the metal raw material liquid, metal
precipitation solvent, and the silicon compound raw material liquid
were changed and the treatment temperature was changed.
[0115] As a further example of changing treatment of the functional
groups contained in the silicon-compound-coated fine silver
particles, hydrogen peroxide was made to act on the
silicon-compound-coated fine silver particles obtained in Example
1-1. Specifically, the silicon-compound-coated fine silver
particles obtained in Example 1-1 were charged into propylene
glycol such as to be 0.1% by weight as silicon-compound-coated fine
silver particles, and using the high-speed rotation-type dispersion
emulsifier CLEARMIX (product name: CLM-2.2S, manufactured by M
Technique Co., Ltd.) stirring at a rotor rotational speed of 20,000
rpm was performed for 30 minutes at a preparation temperature of
30.degree. C. to mix and disperse homogenously and thereby prepare
a silicon-compound-coated fine silver particle dispersion liquid.
While using CLEARMIX to stir the dispersion liquid at 20,000 rpm, a
35% by weight hydrogen peroxide water (manufactured by KANTO
CHEMICAL CO., INC.) was charged in, and the treatment was continued
for 30 minutes while keeping the rotational speed of CLEARMIX at
20,000 rpm and the treatment temperature at 30.degree. C. to
35.degree. C. After the end of the treatment, a dried powder and a
wet cake sample of the silicon-compound-coated fine silver
particles were prepared by the same methods as for Example 1-1 to
Example 1-9. In regard to the charged amount of the hydrogen
peroxide water, the hydrogen peroxide was charged such that the
amount of the hydrogen peroxide with respect to the silver
contained in the silicon-compound-coated fine silver particles
would be 0.005 mol times in Example 1-10, 0.01 mol times in Example
1-11, and 0.1 mol in Example 1-12.
[0116] As a changing treatment of the functional groups contained
in the silicon compound of the silicon-compound-coated fine silver
particles, the silicon-compound-coated fine silver particles of
Example 1-1 were heat-treated using an electric furnace. The heat
treatment conditions were as follows: Example 1-1: untreated;
Example 1-13: at 100.degree. C. for 30 minutes; Example 1-14: at
200.degree. C. for 30 minutes; and Example 1-15: at 300.degree. C.
for 30 minutes.
[0117] As a changing treatment of the functional groups contained
in the silicon compound of the silicon-compound-coated fine silver
particles, the silicon-compound-coated fine silver particles of
Example 1-1 were treated inside a desiccator under a fuming
sulfuric acid atmosphere to make sulfonic acid act on the Si--OH
groups contained in the silicon-compound-coated silver particles
and thereby introduce sulfonic groups. The heat treatment
conditions were as follows: Example 1-1: untreated; Example 1-16:
at room temperature (25.degree. C.) for 120 minutes; and Example
1-17: at room temperature (25.degree. C.) for 480 minutes.
[0118] FIG. 1 shows STEM mapping results of a
silicon-compound-coated fine silver particle obtained in Example
1-1 and FIG. 2 shows results of line analysis at a position
indicated by a broken line in the HAADF image of FIG. 1. In FIG. 1,
(a) is the dark field image (HAADF image), (b) is the mapping
result of oxygen (O), (c) is the mapping result of silicon (Si),
and (d) is the mapping result of zinc (Ag). FIG. 2 shows the
results of line analysis at the position indicated by the broken
line in the HAADF image of FIG. 1, the results indicating atomic %
(mol %) of elements detected along the line segment from one end to
the other end of the particle. As is evident from FIG. 2, whereas
oxygen and silicon were detected up to both ends of the analytical
range of the line analysis, silver was detected only up to parts
several nm inward from the ends of the particle, and it can be
understood that a surface of the fine silver particle is coated
with the silicon compound that contains a silicon oxide. As is
evident from FIG. 1 and FIG. 2, the silicon-compound-coated fine
silver particle obtained in Example 1-1 was observed to be a fine
silver particle, with which an entirety of the particle is covered
with the silicon compound. Although STEM mapping and line analysis
results, similar to those of Example 1-1, were also obtained for
the silicon-compound-coated oxide particles obtained in Example 1-2
to Example 1-17, in regard to Example 1-6, a
silicon-compound-coated fine silver particle was seen with which a
silver particle is not covered entirely by the silicon compound but
with which a surface of the fine silver particle is partially
coated with the silicon compound that contains a silicon oxide. The
present invention can be embodied as silicon-compound-coated fine
metal particles, with which surfaces of metal particles are at
least partially coated with a silicon compound. Also, with each of
Example 1-9, Example 1-14, and Example 1-15, a hollow layer was
seen between a fine silver particle and the silicon compound
covering its surface.
[0119] FIG. 3 shows the results of performing waveform separation
on the wavenumber region of 750 cm.sup.-1 to 1300 cm.sup.-1 of the
FT-IR measurement results for the silicon-compound-coated fine
silver particles obtained in Example 1-7. As is evident from FIG.
3, with the present Example, as results of waveform separation of
peaks in the wavenumber region of 750 cm.sup.-1 to 1300 cm.sup.-1,
an Si--OH-bond-derived peak was deemed to be a peak attributed to a
peak of greatest area ratio among Si--OH-bond-derived peaks,
waveform-separated in a wavenumber region of 850 cm.sup.-1 to 950
cm.sup.-1, an Si--O-bond-derived peak was deemed to be a peak
attributed to a peak of greatest area ratio among
Si--O-bond-derived peaks, waveform-separated in a wavenumber region
of 1000 cm.sup.-1 or more and 1300 cm.sup.-1 or less, the ratio of
Si--OH bonds was deemed to be a ratio of an area of the peak
attributed to the Si--OH bonds with respect to a total area of
peaks obtained by waveform separation of peaks in the wavenumber
region of 750 cm.sup.-1 to 1300 cm.sup.-1, the ratio of Si--O bonds
was deemed to be a ratio of an area of the peak attributed to the
Si--O bonds, and the ratio of Si--OH bonds and the ratio of Si--OH
bonds/Si--O bonds were thereby calculated.
[0120] FIG. 4 shows XRD measurement results of the
silicon-compound-coated fine silver particles obtained in Example
1-1. As is evident from FIG. 4, in the XRD measurement, only the
peak derived from Ag was detected. It was thus confirmed that the
silicon-oxide-containing silicon compound seen in each of the STEM
and IR measurements is an amorphous silicon compound. Similar XRD
measurement results were also obtained for Example 1-2 to Example
1-15.
[0121] The average primary particles diameters, the ratios of
Si--OH bonds (Si--OH bonds ratios), the ratios of Si--O bonds
(Si--O bonds ratios), and the ratios of Si--OH bonds/Si--O bonds
(Si--OH bonds/Si--O bonds ratios) of the silicon-compound-coated
fine silver particles obtained in Example 1-1 to Example 1-15 are
shown in Table 5 together with results indicating, using volume
average particle diameters resulting from particle size
distribution measurements, dispersed particle diameters in
dispersion liquids in which the silicon-compound-coated fine silver
particles obtained in the respective Examples are dispersed in pure
water or toluene (manufactured by KANTO CHEMICAL CO., INC.) as the
dispersion medium. With the present Examples, dispersibility was
evaluated as one of the properties of the silicon-compound-coated
fine metal particles and the dispersibility was evaluated by the
dispersed particle diameter and the dispersed particle diameter
with respect to the average primary particle diameter (dispersed
particle diameter/average primary particle diameter). In regard to
the preparation of the dispersion liquids, the
silicon-compound-coated fine silver particles were charged into
each dispersion medium such as to be 0.1% by weight, and using
CLEARMIX, stirring at a rotor rotational speed of 20,000 rpm was
performed for 30 minutes at a preparation temperature of 30.degree.
C. to mix and disperse homogenously and thereby prepare each
silicon-compound-coated fine silver particle dispersion liquid.
TABLE-US-00006 TABLE 5 Dispersion state Dispersion medium 1:
Dispersion medium 2: Average Si--OH Pure water Toluene primary
Si--OH Si--O bonds/ Dispersed Dispersed particle Dispersed
Dispersed particle particle bonds bonds Si--O particle
diameter/Average particle diameter/Average diameter ratio ratio
bonds diameter primary particle diameter primary particle [nm] [%]
[%] ratio [nm] diameter [nm] diameter Example 1-1 18.6 53.21 0.61
87.2295 59.4 3.2 87.6 4.7 1-2 18.4 48.63 1.43 34.0070 66.5 3.6 85.3
4.6 1-3 18.2 39.33 3.32 11.8464 68.4 3.8 82.1 4.5 1-4 18.3 35.41
8.41 4.2105 71.0 3.9 75.4 4.1 1-5 18.6 56.42 0.43 131.2093 54.6 2.9
88.6 4.8 1-6 18.3 68.42 0.12 570.1667 51.9 2.8 93.6 5.1 1-7 18.4
30.11 11.11 2.7102 74.4 4.0 68.9 3.7 1-8 18.2 28.19 14.16 1.9908
78.9 4.3 66.8 3.7 1-9 18.1 24.21 15.36 1.5762 88.4 4.9 64.3 3.6
1-10 18.3 49.33 1.79 27.5587 64.1 3.5 86.4 4.7 1-11 18.4 36.29 6.48
5.6003 69.3 3.8 77.4 4.2 1-12 18.6 31.43 7.22 4.3532 72.1 3.9 71.2
3.8 1-13 18.4 23.14 17.16 1.3485 92.3 5.0 61.2 3.3 1-14 18.9 8.34
23.46 0.3555 113.1 6.0 41.2 2.2 1-15 19.1 0.18 58.97 0.0031 324.0
17.0 38.6 2.0 1-16 18.7 44.62 2.64 16.9015 67.4 3.6 86.4 4.6 1-17
18.6 37.23 6.54 5.6927 70.1 3.8 79.4 4.3
[0122] As is evident from Table 5, a tendency that the dispersed
particle diameter and the dispersed particle diameter/average
primary particle diameter are decreased by the Si--OH bonds ratio
and the Si--OH bonds/Si--O bonds ratio being increased was seen in
the case of using pure water and ethanol as the dispersion medium,
and a tendency that the dispersed particle diameter and the
dispersed particle diameter/average primary particle diameter are
decreased by the Si--OH bonds/Si--O bonds ratio being decreased was
seen in the case of using toluene as the dispersion medium. Also,
with Example 1-16 and Example 1-17, a sulfo group, which is a
hydrophilic functional group, was seen in the IR measurement
results, and by decrease of the Si--OH bonds ratio or the Si--OH
bonds/Si--O bonds ratio, the dispersibility in pure water decreased
and the dispersibility in toluene improved. FIG. 5 shows a TEM
photograph observed using a collodion membrane prepared with an
aqueous dispersion liquid of the silicon-compound-coated fine
silver particles obtained in Example 1-1.
[0123] With Examples 2 to 4, silicon-compound-coated fine metal
particles were prepared with the metal element in the
silicon-compound-coated fine metal particles being changed (Example
2 and Example 3) or with the treatment apparatus being changed.
Conditions, which differ in metal element or differ in treatment
apparatus but are conditions that are the same in the branch number
of the respective Examples, are conditions, with which, in the
preparation of the silicon-compound-coated fine metal particles,
the purpose is the same and the silicon-compound-coated fine metal
particles are prepared or treated under similar conditions. The
same applies to lists of analysis results and evaluation results of
the respective Examples (Example 2: [Table 10], Example 3: [Table
15], Example 4: [Table 16]).
Example 2
[0124] For Example 2, silicon-compound-coated copper particles,
with which surfaces of fine copper particles, as fine metal
particles, are at least partially coated with a silicon compound,
shall now be described. Other than the preparation conditions being
as indicated in Table 6 to Table 9, preparation was performed under
the same conditions as those of Example 1. The analysis results and
the evaluation results of the obtained silicon-compound-coated fine
copper particles are shown in Table 10. Regarding the substances
indicated by chemical formulas and abbreviations indicated in Table
6 to Table 8, as Cu(NO.sub.3).sub.2.3H.sub.2O, copper nitrate
trihydrate (manufactured by Wako Pure Chemical Industries, Ltd.)
was used as a substance differing from the substances indicated in
Table 1 to Table 3, and other than this, the same substances as
those of Example 1 were used.
Example 3
[0125] For Example 3, silicon-compound-coated nickel particles,
with which surfaces of nickel particles, as fine metal particles,
are at least partially coated with a silicon compound, shall now be
described. Other than the preparation conditions being as indicated
in Table 11 to Table 14, preparation was performed under the same
conditions as those of Example 1. The analysis results and the
evaluation results of the obtained silicon-compound-coated fine
nickel particles are shown in Table 15. Regarding the substances
indicated by chemical formulas and abbreviations indicated in Table
11 to Table 13, as Ni(NO.sub.3).sub.2.6H.sub.2O, nickel nitrate
hexahydrate (manufactured by KANTO CHEMICAL CO., INC.) was used as
a substance differing from the substances indicated in Table 1 to
Table 3 or Table 6 to Table 8, and other than this, the same
substances as those of Example 1 or Example 2 were used.
[0126] Also with both Example 2 and Example 3, results similar to
Example 1 were obtained as the STEM mapping and line analysis
results and the XRD measurement results, only a peak derived from
Cu was detected in the XRD measurement results for Example 2, and
only a peak derived from Ni was detected in the XRD measurement
results for Example 3.
[0127] As is evident from Table 10 and Table 15, results similar to
Example 1 were also obtained for the silicon-compound-coated fine
copper particles and the silicon-compound-coated fine nickel
particles. It was found that even if the metal particles in the
silicon-compound-coated fine metal particles are of metals of
different types, the dispersibility of the silicon-compound-coated
metal particles can be controlled in a range of Si--OH bonds ratio
of 0.1% or more and 70% or less and in a range of Si--OH
bonds/Si--O bonds ratio of 0.001 or more and 700 or less.
TABLE-US-00007 TABLE 6 Formulation of the 1st fluid (Liquid A:
metal raw material liquid) Formulation Raw Raw pH material [wt %]
material [wt %] pH [.degree. C.] Example 2-1 Cu
(NO.sub.3).sub.2.cndot.3H.sub.2O 0.213 Pure water 99.787 3.86 16.3
2-2 Cu (NO.sub.3).sub.2.cndot.3H.sub.2O 0.213 Pure water 99.787
3.86 16.3 2-3 Cu (NO.sub.3).sub.2.cndot.3H.sub.2O 0.213 Pure water
99.787 3.86 16.3 2-4 Cu (NO.sub.3).sub.2.cndot.3H.sub.2O 0.213 Pure
water 99.787 3.86 16.3 2-5 Cu (NO.sub.3).sub.2.cndot.3H.sub.2O
0.213 Pure water 99.787 3.86 16.3 2-6 Cu
(NO.sub.3).sub.2.cndot.3H.sub.2O 0.213 Pure water 99.787 3.86 16.3
2-7 Cu (NO.sub.3).sub.2.cndot.3H.sub.2O 0.054 EG 99.946 2.84 20.9
2-8 Cu (NO.sub.3).sub.2.cndot.3H.sub.2O 0.054 EG 99.946 2.84 20.9
2-9 Cu (NO.sub.3).sub.2.cndot.3H.sub.2O 0.054 EG 99.946 2.84
20.9
TABLE-US-00008 TABLE 7 Formulation of the 2nd fluid (Liquid B:
metal precipitation solvent) Formulation Raw Raw Raw Raw Raw Raw pH
material [wt %] material [wt %] material [wt %] material [wt %]
material [wt %] material [wt %] pH [.degree. C.] Example 2-1
NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000
>14 -- water 2-2 NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 --
0.000 -- 0.000 -- 0.000 >14 -- water 2-3 NaBH.sub.4 0.650 NaOH
1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000 >14 -- water 2-4
NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000
>14 -- water 2-5 NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 --
0.000 -- 0.000 -- 0.000 >14 -- water 2-6 NaBH.sub.4 0.650 NaOH
1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000 >14 -- water 2-7
HMH 20.00 PVP 9.75 DMAE 5.00 KOH 2.55 Pure 7.45 EG 55.25 >14 --
water 2-8 HMH 20.00 PVP 9.75 DMAE 5.00 KOH 2.55 Pure 7.45 EG 55.25
>14 -- water 2-9 HMH 20.00 PVP 9.75 DMAE 5.00 KOH 2.55 Pure 7.45
EG 55.25 >14 -- water
TABLE-US-00009 TABLE 8 Formulation of the 3rd fluid (Liquid C:
silicon compound raw material liquid) Formulation Raw Raw Raw pH
material [wt %] material [wt %] material [wt %] pH [.degree. C.]
Example 2-1 H.sub.2SO.sub.4 0.3100 TEOS 0.1300 MeOH 99.5600 1.75
14.4 2-2 H.sub.2SO.sub.4 0.3100 TEOS 0.1300 MeOH 99.5600 1.75 14.4
2-3 H.sub.2SO.sub.4 0.3100 TEOS 0.1300 MeOH 99.5600 1.75 14.4 2-4
H.sub.2SO.sub.4 0.4320 TEOS 0.1300 MeOH 99.4380 0.26 13.6 2-5
H.sub.2SO.sub.4 0.2340 TEOS 0.1300 MeOH 99.6360 1.89 14.3 2-6
H.sub.2SO.sub.4 0.0560 TEOS 0.1300 MeOH 99.8140 2.84 15.1 2-7 MeOH
1.2300 TEOS 0.0279 EG 98.7421 3.46 23.3 2-8 MeOH 1.2300 TEOS 0.0279
EG 98.7421 3.46 23.3 2-9 MeOH 1.2300 TEOS 0.0279 EG 98.7421 3.46
23.3
TABLE-US-00010 TABLE 9 Introduction Introduction Introduction flow
rate temperature pressure (liquid feed (liquid feed (liquid feed
Discharged Si/M flow rate) temperature) pressure) liquid [molar
ratio] [ml/min] [.degree. C.] [MPaG] Temper- [Calculated Liquid
Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid ature
value] [EDS] A B C A B C A B C pH [.degree. C.] Si M Si M Example
2-1 500 30 85 21 18 17 0.111 0.20 0.20 9.89 23.3 10.7 89.3 10.8
89.2 2-2 500 30 85 39 40 40 0.109 0.20 0.20 9.91 23.4 10.7 89.3
10.6 89.4 2-3 500 30 85 60 61 60 0.113 0.20 0.20 9.87 23.1 10.7
89.3 10.8 89.2 2-4 500 30 85 19 18 19 0.119 0.20 0.20 7.76 23.4
10.7 89.3 10.9 89.1 2-5 500 30 85 19 19 18 0.122 0.20 0.20 11.28
23.9 10.7 89.3 10.8 89.2 2-6 500 30 85 20 20 19 0.114 0.20 0.20
13.28 23.1 10.7 89.3 10.9 89.1 2-7 500 50 100 150 88 111 0.121 0.20
0.20 11.71 29.3 10.7 89.3 10.8 89.2 2-8 500 50 100 191 91 113 0.117
0.20 0.20 11.49 29.1 10.7 89.3 10.9 89.1 2-9 500 50 100 231 90 115
0.116 0.20 0.20 11.67 28.9 10.7 89.3 10.8 89.2
TABLE-US-00011 TABLE 10 Dispersion state Dispersion medium 1:
Dispersion medium 2: Average Si--OH Pure water Toluene primary
Si--OH Si--O bonds/ Dispersed Dispersed particle Dispersed
Dispersed particle particle bonds bonds Si--O particle
diameter/Average particle diameter/Average diameter ratio ratio
bonds diameter primary particle diameter primary particle [nm] [%]
[%] ratio [nm] diameter [nm] diameter Example 2-1 21.2 53.14 0.48
110.71 58.9 2.8 86.3 4.1 2-2 22.3 48.71 1.28 38.055 65.9 3.0 84.3
3.8 2-3 22.1 39.11 3.46 11.303 69.1 3.1 81.2 3.7 2-4 21.1 35.34
8.48 4.1675 72.6 3.4 74.9 3.5 2-5 21.3 56.14 0.31 181.10 55.7 2.6
87.6 4.1 2-6 20.9 68.14 0.11 619.5 52.3 2.5 91.2 4.4 2-7 21.3 30.43
10.62 2.865 75.1 3.5 67.3 3.2 2-8 22.6 28.39 13.84 2.051 79.9 3.5
65.4 2.9 2-9 21.6 24.18 15.26 1.585 89.1 4.1 60.9 2.8 2-10 21.3
48.97 1.81 27.055 64.3 3.0 85.4 4.0 2-11 20.9 35.98 6.51 5.5269
68.9 3.3 77.2 3.7 2-12 21.6 31.36 7.24 4.3315 72.6 3.4 71.9 3.3
2-13 22.1 23.36 17.21 1.3574 91.9 4.2 59.8 2.7 2-14 21.4 9.14 23.54
0.3883 112.3 5.2 42.6 2.0 2-15 21.6 0.45 59.19 0.0076 223.6 10.4
41.1 1.9
TABLE-US-00012 TABLE 11 Formulation of the 1st fluid (Liquid A:
metal raw material liquid) Formulation Raw Raw pH material [wt %]
material [wt %] pH [.degree. C.] 3-1 Ni
(NO.sub.3).sub.2.cndot.6H.sub.2O 0.257 Pure water 99.743 3.86 16.3
3-2 Ni (NO.sub.3).sub.2.cndot.6H.sub.2O 0.257 Pure water 99.743
3.86 16.3 3-3 Ni (NO.sub.3).sub.2.cndot.6H.sub.2O 0.257 Pure water
99.743 3.86 16.3 3-4 Ni (NO.sub.3).sub.2.cndot.6H.sub.2O 0.257 Pure
water 99.743 3.86 16.3 Example 3-5 Ni
(NO.sub.3).sub.2.cndot.6H.sub.2O 0.257 Pure water 99.743 3.86 16.3
3-6 Ni (NO.sub.3).sub.2.cndot.6H.sub.2O 0.257 Pure water 99.743
3.86 16.3 3-7 Ni (NO.sub.3).sub.2.cndot.6H.sub.2O 0.065 EG 99.935
2.74 20.1 3-8 Ni (NO.sub.3).sub.2.cndot.6H.sub.2O 0.065 EG 99.935
2.74 20.1 3-9 Ni (NO.sub.3).sub.2.cndot.6H.sub.2O 0.065 EG 99.935
2.74 20.1
TABLE-US-00013 TABLE 12 Formulation of the 2nd fluid (Liquid B:
metal precipitation solvent) Formulation Raw Raw Raw Raw Raw Raw pH
material [wt %] material [wt %] material [wt %] material [wt %]
material [wt %] material [wt %] pH [.degree. C.] Example 3-1
NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000
>14 -- water 3-2 NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 --
0.000 -- 0.000 -- 0.000 >14 -- water 3-3 NaBH.sub.4 0.650 NaOH
1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000 >14 -- water 3-4
NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000
>14 -- water 3-5 NaBH.sub.4 0.650 NaOH 1.000 Pure 98.350 --
0.000 -- 0.000 -- 0.000 >14 -- water 3-6 NaBH.sub.4 0.650 NaOH
1.000 Pure 98.350 -- 0.000 -- 0.000 -- 0.000 >14 -- water 3-7
HMH 20.00 PVP 9.75 DMAE 5.00 KOH 2.55 Pure 7.45 EG 55.25 >14 --
water 3-8 HMH 20.00 PVP 9.75 DMAE 5.00 KOH 2.55 Pure 7.45 EG 55.25
>14 -- water 3-9 HMH 20.00 PVP 9.75 DMAE 5.00 KOH 2.55 Pure 7.45
EG 55.25 >14 -- water
TABLE-US-00014 TABLE 13 Formulation of the 3rd fluid (Liquid C:
silicon compound raw material liquid) Formulation Raw Raw Raw pH
material [wt %] material [wt %] material [wt %] pH [.degree. C.]
Example 3-1 H.sub.2SO.sub.4 0.3100 TEOS 0.1300 MeOH 99.5600 1.75
14.4 3-2 H.sub.2SO.sub.4 0.3100 TEOS 0.1300 MeOH 99.5600 1.75 14.4
3-3 H.sub.2SO.sub.4 0.3100 TEOS 0.1300 MeOH 99.5600 1.75 14.4 3-4
H.sub.2SO.sub.4 0.4320 TEOS 0.1300 MeOH 99.4380 0.26 13.6 3-5
H.sub.2SO.sub.4 0.2340 TEOS 0.1300 MeOH 99.6360 1.89 14.3 3-6
H.sub.2SO.sub.4 0.0560 TEOS 0.1300 MeOH 99.8140 2.84 15.1 3-7 MeOH
1.2300 TEOS 0.0279 EG 98.7421 3.46 23.3 3-8 MeOH 1.2300 TEOS 0.0279
EG 98.7421 3.46 23.3 3-9 MeOH 1.2300 TEOS 0.0279 EG 98.7421 3.46
23.3
TABLE-US-00015 TABLE 14 Introduction Introduction Introduction flow
rate temperature pressure (liquid feed (liquid feed (liquid feed
Discharged Si/M flow rate) temperature) pressure) liquid [molar
ratio] [ml/min] [.degree. C.] [MPaG] Temper- [Calculated Liquid
Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid ature
value] [EDS] A B C A B C A B C pH [.degree. C.] Si M Si M Example
3-1 500 30 85 20 19 16 0.119 0.20 0.20 9.89 23.3 10.7 89.3 10.8
89.2 3-2 500 30 85 42 41 39 0.122 0.20 0.20 9.91 23.4 10.7 89.3
10.8 89.2 3-3 500 30 85 59 60 62 0.119 0.20 0.20 9.87 23.1 10.7
89.3 10.6 89.4 3-4 500 30 85 20 19 18 0.122 0.20 0.20 7.76 23.4
10.7 89.3 10.8 89.2 3-5 500 30 85 18 20 19 0.114 0.20 0.20 11.28
23.9 10.7 89.3 10.8 89.2 3-6 500 30 85 21 18 19 0.114 0.20 0.20
13.28 23.1 10.7 89.3 10.6 89.4 3-7 500 50 100 153 86 110 0.114 0.20
0.20 11.71 29.3 10.7 89.3 10.8 89.2 3-8 500 50 100 193 90 111 0.119
0.20 0.20 11.49 29.1 10.7 89.3 10.5 89.5 3-9 500 50 100 234 91 113
0.122 0.20 0.20 11.67 28.9 10.7 89.3 10.8 89.2
TABLE-US-00016 TABLE 15 Dispersion state Dispersion medium 1:
Dispersion medium 2: Average Si--OH Pure water Toluene primary
Si--OH Si--O bonds/ Dispersed Dispersed particle Dispersed
Dispersed particle particle bonds bonds Si--O particle
diameter/Average particle diameter/Average diameter ratio ratio
bonds diameter primary particle diameter primary particle [nm] [%]
[%] ratio [nm] diameter [nm] diameter Example 3-1 32.1 52.99 0.41
129.2 56.9 1.8 87.3 2.7 3-2 33.1 49.54 1.43 34.6 63.9 1.9 85.3 2.6
3-3 33.1 38.87 3.28 11.9 67.1 2.0 82.2 2.5 3-4 32.4 35.49 8.54 4.2
70.6 2.2 75.9 2.3 3-5 31.3 55.84 0.24 232.7 53.7 1.7 88.6 2.8 3-6
32.3 68.27 0.14 487.6 49.3 1.5 91.2 2.8 3-7 33.4 31.28 10.28 3.0
72.1 2.2 65.9 2.0 3-8 31.9 27.54 14.23 1.9 77.9 2.4 63.2 2.0 3-9
33.9 23.84 15.46 1.5 87.9 2.6 57.7 1.7 3-10 32.6 48.64 1.76 27.6364
63.9 2.0 84.9 2.6 3-11 33.1 34.87 6.38 5.4655 69.1 2.1 76.9 2.3
3-12 32.9 32.14 7.46 4.3083 73.2 2.2 72.3 2.2 3-13 34.6 23.69 17.54
1.3506 92.1 2.7 60.1 1.7 3-14 33.6 8.43 24.13 0.3494 114.6 3.4 45.6
1.4 3-15 31.9 0.59 60.21 0.0098 396.3 12.4 42.1 1.3
Example 4
[0128] As Example 4, silicon-compound-coated silver particles were
prepared with conditions being the same as those in Example 1 with
the exception of employing the apparatus and procedures described
in Publication of JP 2009-112892 for mixing and reacting a liquid
A, a liquid B, and liquid C. Here, as the apparatus of Publication
of JP 2009-112892, the apparatus described in FIG. 1 of that
publication was used, with the inner diameter of the stirring tank
being 80 mm, the gap between the outer end of the stirring tool and
the inner peripheral side surface of the stirring tank being 0.5
mm, and the rotational speed of the stirring blade being 7,200 rpm.
Also, the liquid A was introduced into the stirring tank, and the
liquid B was then added to a thin film composed of the liquid A
being pressed against the inner peripheral side surface of the
stirring tank to make the liquids become mixed and react with each
other.
[0129] Results similar to Example 1 were obtained as the STEM
mapping and line analysis results and the XRD measurement
results.
[0130] The analysis results and the evaluation results for the
silicon-compound-coated fine silver particles obtained in Example 4
are shown in Table 16. As is evident from Table 16, it was found
that even with Example 4, which was carried out using an apparatus
differing from the apparatus described in Patent Literature 5, the
dispersibility can be controlled by controlling the Si--OH bonds
ratio or the Si--OH bonds/Si--O bonds ratio in the
silicon-compound-coated fine metal particles as in Examples 1 to
3.
TABLE-US-00017 TABLE 16 Dispersion state Dispersion medium 1:
Dispersion medium 2: Average Si--OH Pure water Toluene primary
Si--OH Si--O bonds/ Dispersed Dispersed particle Dispersed
Dispersed particle particle bonds bonds Si--O particle
diameter/Average particle diameter/Average diameter ratio ratio
bonds diameter primary particle diameter primary particle [nm] [%]
[%] ratio [nm] diameter [nm] diameter Example 4-1 64.3 52.96 0.63
84.0635 146.1 2.3 195.3 3.0 4-2 66.9 47.89 1.44 33.2569 163.5 2.4
190.2 2.8 4-3 65.9 38.29 3.42 11.1959 168.3 2.6 183.1 2.8 4-4 65.4
34.91 8.16 4.2782 174.5 2.7 168.1 2.6 4-5 67.4 55.36 0.39 141.9487
134.3 2.0 206.1 3.1 4-6 68.1 67.39 0.18 374.3889 127.7 1.9 208.7
3.1 4-7 65.1 29.98 10.76 2.7862 183.0 2.8 153.6 2.4 4-8 65.6 27.08
13.79 1.9637 194.1 3.0 149.0 2.3 4-9 66.3 23.46 14.97 1.5671 217.3
3.3 143.4 2.2 4-10 68.1 48.61 1.65 29.4606 157.8 2.3 192.7 2.8 4-11
67.2 35.89 6.51 5.5131 170.5 2.5 172.6 2.6 4-12 64.3 30.97 7.46
4.1515 177.4 2.8 158.8 2.5 4-13 65.1 29.97 17.29 1.7334 181.2 2.8
153.4 2.4 4-14 68.9 8.46 24.51 0.3452 278.2 4.0 91.9 1.3 4-15 67.3
0.89 59.14 0.0150 364.2 5.4 82.1 1.2
Example 5
[0131] As Example 5, an example of producing
silicon-compound-coated fine metal particles using
silicon-compound-coated precursor particles and controlling the
ratio of Si--OH bonds or the ratio of Si--OH bonds/Si--O bonds
shall now be described. As the silicon-compound-coated fine
precursor particles, silicon-compound-coated,
silicon-aluminum-doped fine iron oxide particles were prepared. In
regard to the preparation conditions, besides preparing based on
the formulation conditions indicated in Table 17 to Table 19 and
using the treatment conditions indicated in Table 20, the
silicon-compound-coated, silicon-aluminum-doped fine iron oxide
particles were prepared by the same method as that of Example 1.
Oxide particles are prepared in an initial stage of Example 5 and
therefore the metal raw material liquid is indicated as an oxide
raw material liquid and the metal precipitation solvent is
indicated as an oxide precipitation solvent. Regarding the
substances indicated by chemical formulas and abbreviations
indicated in Table 17 to Table 19, as Fe(NO.sub.3).sub.3.9H.sub.2O,
iron nitrate nonahydrate (manufactured by KANTO CHEMICAL CO., INC.)
was used and, as Al(NO.sub.3).sub.3.9H.sub.2O, aluminum nitrate
nonahydrate (manufactured by KANTO CHEMICAL CO., INC.) was used as
substances differing from the substances indicated in Table 1 to
Table, Table 6 to Table 8, or Table 11 to Table 13, and other than
these, the same substances as those of Example 1 to Example 4 were
used.
TABLE-US-00018 TABLE 17 Formulation of the 1st fluid (Liquid A:
oxide raw material liquid) Formulation Raw Raw Raw Raw pH material
[wt %] material [wt %] material [wt %] material [wt %] pH [.degree.
C.] Example 5 Fe (NO.sub.3).sub.3.cndot.9H.sub.2O 3.000 TEOS 0.286
Al (NO.sub.3).sub.3.cndot.9H.sub.2O 0.056 Pure water 96.658 0.48
19.3
TABLE-US-00019 TABLE 18 Formulation of the 2nd fluid (Liquid B:
oxide precipitation solvent) Formulation Raw Raw pH material [wt %]
material [wt %] pH [.degree. C.] Example 5 NaOH 13.50 Pure water
86.50 >14 --
TABLE-US-00020 TABLE 19 Formulation of the 3rd fluid (Liquid C:
silicon compound raw material liquid) Formulation Raw Raw pH
material [wt %] material [wt %] pH [.degree. C.] Example 5 MeOH
99.5361 TEOS 0.4639 4.98 19.1
TABLE-US-00021 TABLE 20 Introduction Introduction Introduction flow
rate temperature pressure Si (core + shell)/ (liquid feed (liquid
feed (liquid feed Discharged M (Fe + Al) flow rate) temperature)
pressure) liquid [molar ratio] [ml/min] [.degree. C.] [MPaG]
Temper- [Calculated Liquid Liquid Liquid Liquid Liquid Liquid
Liquid Liquid Liquid ature value] [EDS] A B C A B C A B C pH
[.degree. C.] Si M Si M Example 5 400 40 50 141 89 88 0.415 0.20
0.20 11.69 23.9 6.8 93.2 6.9 93.1
[0132] The silicon-compound-coated, silicon-aluminum-doped fine
iron oxide particles obtained in Example 5 were heat-treated inside
a reducing furnace with an argon gas, containing hydrogen, being
made to flow through the reducing furnace as a reducing atmosphere.
Hydrogen concentration, treatment temperatures, and treatment times
in the gas being made to flow through the reducing furnace, the
average primary particles diameters, the ratios of Si--OH bonds
(Si--OH bonds ratios), the ratios of Si--O bonds (Si--O bonds
ratios), and the ratios of Si--OH bonds/Si--O bonds (Si--OH
bonds/Si--O bonds ratios) of the silicon-compound-coated metal
particles obtained are shown in Table 21 together with results
indicating, using volume average particle diameters resulting from
particle size distribution measurements, dispersed particle
diameters in dispersion liquids in which the
silicon-compound-coated fine metal particles obtained in the
respective Examples are dispersed in pure water or toluene
(manufactured by KANTO CHEMICAL CO., INC.) as the dispersion
medium. (The results for Example 5-1 to Example 5-10 are those for
silicon-compound-coated metal particles.)
TABLE-US-00022 TABLE 21 Dispersion state Dispersion Dispersion
medium 1: medium 2: Pure water Toluene Dispersed Dispersed particle
particle Reducing atmosphere conditions Average Si--OH diameter/
diameter/ Hydrogen Treatment primary Si--OH Si--O bonds/ Dispersed
Average Dispersed Average concen- Gas temper- Treatment particle
bonds bonds Si--O particle primary particle primary tration flow
ature time diameter ratio ratio bonds diameter particle diameter
particle [%] [L/min] [.degree. C.] [min] [nm] [%] [%] ratio [nm]
diameter [nm] diameter Example 5 -- -- -- -- 9.5 -- -- -- -- -- --
-- 5-1 3 5 400 30 23.1 58.8 6.7 8.78 51.9 2.2 165.4 7.2 5-2 3 5 450
30 24.6 46.8 9.1 5.14 54.6 2.2 156.3 6.4 5-3 3 5 500 30 23.9 37.9
15.4 2.46 65.4 2.7 131.2 5.5 5-4 3 5 550 30 24.6 28.6 18.4 1.55
68.9 2.8 111.2 4.5 5-5 3 5 600 30 36.4 19.3 24.1 0.80 112.1 3.1
131.2 3.6 5-6 3 5 600 60 116.4 13.9 35.4 0.39 431.2 3.7 361.1 3.1
5-7 3 5 600 90 236.4 6.7 43.9 0.15 896.3 3.8 461.2 2.0 5-8 3 5 650
60 346.2 2.3 68.4 0.03 1346.2 3.9 631.2 1.8
[0133] STEM mapping results for a silicon-compound-coated,
silicon-aluminum-doped fine iron particle obtained in Example 5-5
are shown in FIG. 6. As is evident from FIG. 5, it can be
understood that a surface of a silicon-aluminum-doped fine iron
particle is coated with a silicon compound that contains a silicon
oxide. Similar STEM mapping results were also obtained for Example
5-1 to Example 5-4 and Example 5-6 to Example 5-8. It was also
confirmed that with increase of the treatment temperature or
extension of the treatment time, the silicon contained in the
silicon-aluminum-doped fine iron particle migrates toward a
vicinity of a surface layer of the particle.
[0134] From XRD measurement results, whereas a peak of magnetite or
other oxide was seen with the silicon-compound-coated,
silicon-aluminum-doped fine iron particles obtained under the
conditions of each of Example 5-1 to Example 5-3, an oxide peak was
not seen and a peak close to a peak of only iron was seen with the
silicon-aluminum-doped iron particles obtained in Example 5-4 to
Example 5-8. As a representative, the measurement results for
Example 5-5 are shown in FIG. 7. In FIG. 8, peak positions of iron
(Fe: metal) in a database are shown with respect to a peak list of
the measurement results shown in FIG. 7 with the vicinities of the
respective peaks being enlarged. As is evident from FIG. 8, it can
be understood that the XRD measurement results for the
silicon-aluminum-doped fine iron particles obtained in Example 5-5
indicate peaks being close to those of iron but shifted in peak
position with respect to those of iron itself. It is considered
that the above XRD measurement results were obtained due to the
silicon-aluminum-doped fine iron particle being that with which
iron, silicon, and aluminum form a solid solution.
[0135] As is evident from Table 21, it was found that
silicon-compound-coated metal particles are obtained by treating
silicon-compound-coated fine precursor particles in a reducing
atmosphere and that the dispersibility of the
silicon-compound-coated fine metal particles can be controlled by
controlling the Si--OH bonds/Si--O bonds ratio contained in the
silicon-compound-coated fine metal particles as well.
* * * * *