U.S. patent application number 12/913035 was filed with the patent office on 2011-05-05 for fine particle dispersion liquid containing tantalum oxide fine particles, tantalum oxide fine particle-resin composite, and method of producing fine particle dispersion liquid.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Seiji Okada.
Application Number | 20110105666 12/913035 |
Document ID | / |
Family ID | 43926096 |
Filed Date | 2011-05-05 |
United States Patent
Application |
20110105666 |
Kind Code |
A1 |
Okada; Seiji |
May 5, 2011 |
FINE PARTICLE DISPERSION LIQUID CONTAINING TANTALUM OXIDE FINE
PARTICLES, TANTALUM OXIDE FINE PARTICLE-RESIN COMPOSITE, AND METHOD
OF PRODUCING FINE PARTICLE DISPERSION LIQUID
Abstract
Provided are fine particle dispersion liquid containing tantalum
oxide fine particles each having a small crystallite size and
uniformly dispersed in an organic solvent, a tantalum oxide fine
particle-resin composite, and a method of producing the dispersion
liquid. The method of producing a fine particle dispersion liquid
containing tantalum oxide fine particles includes: preparing a
mixture of the tantalum oxide fine particles, a basic compound, a
surface modifier, and an organic solvent; and subjecting the
mixture to a dispersion treatment.
Inventors: |
Okada; Seiji; (Kawasaki-shi,
JP) |
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
43926096 |
Appl. No.: |
12/913035 |
Filed: |
October 27, 2010 |
Current U.S.
Class: |
524/408 |
Current CPC
Class: |
C08K 9/08 20130101; Y10T
428/2991 20150115; Y10T 428/2995 20150115; C08K 9/04 20130101 |
Class at
Publication: |
524/408 |
International
Class: |
C08K 3/22 20060101
C08K003/22 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 2009 |
JP |
2009-251486(PAT.) |
Claims
1. A method of producing a fine particle dispersion liquid
containing tantalum oxide fine particles, the method comprising:
preparing a mixture of the tantalum oxide fine particles, a basic
compound, a surface modifier, and an organic solvent; and
subjecting the mixture to a dispersion treatment.
2. The method of producing a fine particle dispersion liquid
according to claim 1, wherein the basic compound comprises an
organic amine compound.
3. The method of producing a fine particle dispersion liquid
according to claim 1, wherein the basic compound comprises at least
one basic compound selected from the group consisting of
triethylamine, butylamine, dibutylamine, aniline, pyridine,
tetramethylethylenediamine, and 2-(2-aminoethoxy)ethanol.
4. The method of producing a fine particle dispersion liquid
according to claim 1, wherein the surface modifier comprises a
silane coupling agent.
5. The method of producing a fine particle dispersion liquid
according to claim 1, wherein the surface modifier comprises
3-methacryloxypropyltriethoxysilane.
6. The method of producing a fine particle dispersion liquid
according to claim 1, wherein the organic solvent comprises at
least one of tetrahydrofuran and methyl methacrylate.
7. A method of producing a fine particle dispersion liquid
containing tantalum oxide fine particles, the method comprising:
preparing a mixture of the tantalum oxide fine particles, a basic
compound, a surface modifier, and an organic solvent; and
subjecting the mixture to a dispersion treatment, wherein the
dispersion treatment is based on one of a bead mill method and a
jet mill method.
8. A fine particle dispersion liquid containing tantalum oxide,
comprising: tantalum oxide fine particles each of which has a
crystallite size of 10 nm or less and is covered with a surface
modifier; a basic compound; and an organic solvent.
9. The fine particle dispersion liquid according to claim 8,
wherein the tantalum oxide fine particles each have a
volume-average particle diameter of 20 nm or less.
10. A fine particle-resin composite obtained from the fine particle
dispersion liquid according to claim 8.
11. A method of producing a fine particle dispersion liquid
containing tantalum oxide fine particles, the method comprising:
preparing the tantalum oxide fine particles; mixing the tantalum
oxide fine particles prepared, a basic compound, a surface
modifier, and an organic solvent to obtain a mixture; and
subjecting the mixture to a dispersion treatment.
12. A method of producing a fine particle-resin composite, the
method comprising: preparing tantalum oxide fine particles; mixing
the tantalum oxide fine particles prepared, a basic compound, a
surface modifier, and a curable monomer to obtain a mixture;
subjecting the mixture to a dispersion treatment; and polymerizing
the curable monomer in the mixture.
13. A method of producing a fine particle-resin composite, the
method comprising: mixing a fine particle dispersion liquid
produced by the method according to claim 11 and a resin to obtain
a mixed liquid; and polymerizing the resin in the mixed liquid.
14. A method of producing a fine particle-resin composite, the
method comprising: obtaining tantalum oxide fine particles coated
with a surface modifier from a fine particle dispersion liquid
produced by the method according to claim 11; melting and kneading
the tantalum oxide fine particles and a resin; and polymerizing the
resin.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a fine particle dispersion
liquid containing tantalum oxide fine particles, a tantalum oxide
fine particle-resin composite, and a method of producing a fine
particle dispersion liquid.
[0003] 2. Description of the Related Art
[0004] In recent years, researches on the formation of a colorless,
transparent, high-refractive index resin have been vigorously
conducted with a view to increasing the refractive index of a
resin. The formation involves introducing fine particles of a metal
oxide having a high refractive index such as titanium oxide,
zirconium oxide, zinc oxide, tantalum oxide, or niobium oxide, or a
composite oxide of two or more of such metal oxides into the resin
while maintaining a dispersed state.
[0005] The high-refractive index, transparent resin has been
expected to find applications in various optical materials because
the resin is a material bringing together the characteristics of an
organic polymer such as transparency, flexibility, a light weight,
and ease of molding, and the characteristics of an inorganic
compound such as a high refractive index, a high strength, and heat
resistance. Specific examples of the optical materials include:
light guides provided for optical fibers, optical wiring boards,
and the like; the parts and optical lenses of various instruments
such as an image sensor, a camera, and a copying machine; various
display materials; and resin compositions for sealing optical
semiconductor devices such as a printed wiring board and a
light-emitting diode.
[0006] It has been generally said that, in order for a metal oxide
fine particle-resin composite to be transparent, the following
requirements have only to be satisfied. That is, metal oxide fine
particles are uniformly dispersed in a resin, and the
volume-average particle diameter of each of the metal oxide fine
particles is equal to or less than a quarter of the wavelength of
visible light. It has also been generally said that the
volume-average particle diameter is desired to be as small as
possible. However, the metal oxide fine particles are apt to
agglomerate as their particle diameters become smaller, and hence
it has been difficult to disperse the metal oxide fine particles
having small particle diameters in the resin uniformly and
stably.
[0007] A method of solving the problem is, for example, an approach
involving subjecting metal oxide fine particles such as zirconia
particles to a dispersion treatment in the presence of a surface
modifier such as a silane coupling agent to disperse the metal
oxide fine particles in a solvent or a resin uniformly and stably
as described in each of Japanese Patent Application Laid-Open No.
H03-12460 and Japanese Patent Application Laid-Open No.
2008-120848.
[0008] As described above, a metal oxide having a high refractive
index is, for example, titanium oxide, zirconium oxide, zinc oxide,
tantalum oxide, or niobium oxide. Tantalum oxide has a wider band
gap than that of any other high-refractive index metal oxide such
as titanium oxide, zinc oxide, or niobium oxide, and hence is
substantially free of photocatalytic activity with visible light.
Accordingly, a tantalum oxide-resin composite has a small influence
on a resin caused by the photocatalytic activity of tantalum oxide
and is excellent in light fastness. Although zirconium oxide is
also a metal oxide having a wide band gap and free of
photocatalytic activity, the refractive index of zirconium oxide is
lower than that of tantalum oxide. By reason of the foregoing,
expectations have been placed on the potential of tantalum oxide to
serve as a new high-refractive index material.
[0009] However, it has been difficult to obtain tantalum oxide
particles each having high dispersibility in a solvent or a resin
and a small crystallite size at an inexpensive price.
SUMMARY OF THE INVENTION
[0010] An object of the present invention is to provide a fine
particle dispersion liquid containing tantalum oxide fine particles
each having a small crystallite size and uniformly dispersed in an
organic solvent, a tantalum oxide fine particle-resin composite,
and a method of producing the dispersion liquid for solving the
above-mentioned problem.
[0011] A method of producing a fine particle dispersion liquid
containing tantalum oxide fine particles according to an aspect of
the present invention includes: preparing a mixture of the tantalum
oxide fine particles, a basic compound, a surface modifier, and an
organic solvent; and subjecting the mixture to a dispersion
treatment.
[0012] A fine particle dispersion liquid containing tantalum oxide
fine particles according to another aspect of the present invention
includes: tantalum oxide fine particles each of which has a
crystallite size of 10 nm or less and is covered with a surface
modifier; a basic compound; and an organic solvent.
[0013] According to the method of producing a fine particle
dispersion liquid containing tantalum oxide fine particles of the
present invention, when the dispersion treatment is performed in
the organic solvent containing the tantalum oxide fine particles,
the basic compound, and the surface modifier, the crystallite size
of each of the tantalum oxide fine particles reduces as compared
with that before the dispersion treatment. Further, the fine
particle dispersion liquid containing the tantalum oxide fine
particles where the tantalum oxide fine particles are uniformly
dispersed in the organic solvent is obtained.
[0014] The fine particle dispersion liquid containing tantalum
oxide fine particles of the present invention can be easily
compatible with a resin because both the crystallite size and
volume-average particle diameter of each of the tantalum oxide fine
particles are small enough for the tantalum oxide fine particles to
be uniformly dispersed in the organic solvent. In addition, a
tantalum oxide fine particle-resin composite produced by using the
tantalum oxide fine particles or fine particle dispersion liquid
containing tantalum oxide fine particles of the present invention
has high transparency.
[0015] In addition, the use of the organic solvent of the fine
particle dispersion liquid containing tantalum oxide fine particles
of the present invention with one or both of a thermosetting
monomer and a photocurable monomer allows one to integrate the
method of producing a fine particle dispersion liquid containing
tantalum oxide fine particles and the method of producing a
tantalum oxide fine particle-resin composite of the present
invention into a single method. Accordingly, the present invention
can provide not only a tantalum oxide fine particle-resin composite
having high transparency but also a simple method of producing the
composite.
[0016] Further features of the present invention will become
apparent from the following description of exemplary embodiments
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a TEM photograph of tantalum oxide fine particles
in a fine particle dispersion liquid containing the tantalum oxide
fine particles obtained in Example 1 of the present invention.
[0018] FIG. 2 is a schematic view for illustrating a fine
particle-resin composite according to an embodiment of the present
invention.
DESCRIPTION OF THE EMBODIMENTS
[0019] Hereinafter, the embodiments of the present invention are
described in detail. It should be noted that the embodiments to be
individually disclosed are examples of the method of producing a
fine particle dispersion liquid containing tantalum oxide fine
particles, fine particle dispersion liquid containing tantalum
oxide fine particles, and tantalum oxide fine particle-resin
composite and method of producing the composite of the present
invention and the present invention is not limited to the
examples.
[0020] (Method of Producing Tantalum Oxide Fine Particles)
[0021] The method of producing a fine particle dispersion liquid
containing tantalum oxide fine particles according to an embodiment
of the present invention includes: preparing a mixture of the
tantalum oxide fine particles, a basic compound, a surface
modifier, and an organic solvent; and subjecting the mixture to a
dispersion treatment. When the dispersion treatment is performed in
the organic solvent containing the tantalum oxide fine particles,
the basic compound, and the surface modifier, the crystallite size
of each of the tantalum oxide fine particles reduces as compared
with that before the dispersion treatment. A possible reason for
the fact that the crystallite size of each of the tantalum oxide
fine particles reduces as described above is that the basic
compound dissolves the tantalum oxide fine particles. Further, the
resultant fine particle dispersion liquid containing the tantalum
oxide fine particles is such that the tantalum oxide fine particles
are uniformly dispersed in the organic solvent.
[0022] The terms "tantalum oxide fine particles," "basic compound,"
"surface modifier," and "organic solvent" as used herein are
described later.
[0023] The doses of the tantalum oxide fine particles, the basic
compound, and the surface modifier added to the organic solvent
fall within the following ranges.
[0024] In the dispersing step, the tantalum oxide fine particles
are preferably used at a ratio of 1 wt % or more to 50 wt % or less
with respect to the organic solvent. In consideration of the
dispersion efficiency and productivity of the fine particle
dispersion liquid containing the tantalum oxide fine particles, the
ratio is more preferably 5 wt % or more to 30 wt % or less.
[0025] In the dispersing step, the surface modifier is used at a
ratio of preferably 5 wt % or more to 200 wt % or less, more
preferably 30 wt % or more to 150 wt % or less with respect to the
tantalum oxide fine particles.
[0026] The reasons for the preferred ratio are as described below.
When the weight ratio of the surface modifier is less than 5 wt %,
it becomes difficult to disperse the tantalum oxide fine particles
in the organic solvent. As a result, the transparency of the fine
particle dispersion liquid containing the tantalum oxide fine
particles is lost. On the other hand, when the weight ratio of the
surface modifier exceeds 200 wt %, an influence of the surface
modifier on the refractive index of the tantalum oxide enlarges. As
a result, the refractive index of the fine particle dispersion
liquid containing the tantalum oxide fine particles reduces.
[0027] In the dispersing step, the basic compound is used at a
ratio of preferably 0.01 wt % or more to 50 wt % or less, more
preferably 1 wt % or more to 30 wt % or less with respect to the
tantalum oxide fine particles. The reasons for the preferred ratio
are as described below. When the weight ratio of the basic compound
is less than 0.01 wt % with respect to the tantalum oxide fine
particles, such effect that the crystallite size of each of the
tantalum oxide fine particles reduces cannot be sufficiently
obtained. On the other hand, when the weight ratio of the basic
compound exceeds 50 wt %, an influence of the basic compound on the
refractive index of the tantalum oxide enlarges. As a result, the
refractive index of the fine particle dispersion liquid containing
the tantalum oxide fine particles reduces.
[0028] A dispersion method employed in the dispersion treatment is
not particularly limited, and examples of the method include wet
dispersion methods such as a ball mill method, a vibration mill
method, a planetary ball mill method, a bead mill method, a jet
mill method, and a homogenizer method. Of those, the bead mill
method or the jet mill method is preferably employed. This is
because, in the bead mill method or the jet mill method, the
particles can be shredded by applying a stronger force to each of
the particles than that in any one of the other methods described
above.
[0029] When the bead mill method is employed, beads to be used are
not particularly limited, but zirconia beads each having high
abrasion resistance are preferably used in order that the inclusion
of impurities in the fine particle dispersion liquid containing the
tantalum oxide fine particles may be avoided. The beads each have a
particle diameter of preferably 1 .mu.m or more to 100 .mu.m or
less, particularly preferably 20 .mu.m or more to 50 .mu.m or less.
When the particle diameter of each of the beads is less than 1
.mu.m, an impact force on a raw material powder is small, and hence
the dispersion requires a long time. On the other hand, when the
particle diameter of each of the beads exceeds 100 .mu.m, the
impact force on the raw material powder becomes so large that the
dispersed particles each have increased surface energy and their
reagglomeration is apt to occur. In addition, the filling factor of
the beads, which is not particularly limited, is generally 30% or
more to 90% or less, and is preferably 40% or more to 70% or less
from the viewpoints of the viscosity and dispersion efficiency of
the tantalum oxide dispersion liquid.
[0030] As described above, the fine particle dispersion liquid
containing tantalum oxide fine particles according to the
embodiment of the present invention is produced by the production
method including: preparing the mixture of the tantalum oxide fine
particles, the basic compound, the surface modifier, and the
organic solvent; and subjecting the mixture to the dispersion
treatment.
[0031] Accordingly, the contents of the tantalum oxide fine
particles, the organic solvent, the basic compound, and the surface
modifier in the fine particle dispersion liquid containing the
tantalum oxide fine particles according to the embodiment of the
present invention also fall within the above-mentioned ranges.
[0032] That is, the tantalum oxide fine particles are preferably
used at a ratio of 1 wt % or more to 50 wt % or less with respect
to the organic solvent. In consideration of the dispersion
efficiency and productivity of the fine particle dispersion liquid
containing the tantalum oxide fine particles, the ratio is more
preferably 5 wt % or more to 30 wt % or less.
[0033] In addition, the surface modifier is used at a ratio of
preferably 5 wt % or more to 200 wt % or less, more preferably 30
wt % or more to 150 wt % or less with respect to the tantalum oxide
fine particles.
[0034] Further, the basic compound is used at a ratio of preferably
0.01 wt % or more to 50 wt % or less, more preferably 1 wt % or
more to 30 wt % or less with respect to the tantalum oxide fine
particles.
[0035] In the method of producing the tantalum oxide fine particles
according to the embodiment of the present invention, the purifying
step of removing the surface modifier, which is chemically bonded
to the surface of each of the tantalum oxide fine particles and
does not contribute to a surface treatment, to purify the
dispersion liquid can be added as required after the dispersion
treatment. The removing step of removing coarse particles in the
fine particle dispersion liquid containing the tantalum oxide fine
particles obtained in the production method can also be added.
Although those steps are not particularly limited, examples of the
steps include an ultrafiltration method, a centrifugal separation
method, and a reprecipitation method.
[0036] (Fine Particle Dispersion Liquid Containing Tantalum Oxide
Fine Particles)
[0037] A fine particle dispersion liquid containing tantalum oxide
fine particles according to another embodiment of the present
invention contains: tantalum oxide fine particles each of which has
a crystallite size of 10 nm or less and is covered with a surface
modifier; a basic compound; and an organic solvent.
[0038] The term "crystallite size" as used herein refers to the
particle diameter of the minimum unit (primary particle) forming
each particle. The particle diameter is a value D(110) calculated
from the X-ray diffraction peak of the (110) surface of a particle
obtained with an X-ray diffractometer (XRD) by using
Debye-Scherrer's equation (Eq. 1) described below. It should be
noted that the value D(110) is calculated from the following
equation:
D(110)=K*.lamda./.beta. cos .theta. (Eq. 1)
[0039] where D(110) represents a crystallite size (crystallite
size), K=0.9, .lamda.Cu-K.alpha.1=0.154056 nm, and represents the
half width of the diffraction peak.
[0040] (Tantalum Oxide Fine Particles)
[0041] The structures of the tantalum oxide fine particles in the
fine particle dispersion liquid containing the tantalum oxide fine
particles according to the embodiment of the present invention are
not particularly limited, and may be any one, or a mixture, of an
.alpha.-type structure, .beta.-type structure, a .delta.-type
structure, and an amorphous structure.
[0042] A tantalum oxide fine particle-resin composite having high
transparency is obtained because the tantalum oxide fine particles
each have a crystallite size of 1 nm or more to 10 nm or less. In
addition, the surface of each of the tantalum oxide fine particles
is covered with the surface modifier, and hence a tantalum oxide
fine particle-resin composite having the tantalum oxide fine
particles uniformly and stably dispersed in a resin is
obtained.
[0043] In addition, the above-mentioned tantalum oxide fine
particles may be in a powder state or in a dispersion state in
which the fine particles are dispersed in a solvent.
[0044] Further, the volume-average particle diameter of each of the
tantalum oxide fine particles is preferably 1 nm or more to 20 nm
or less. The term "volume-average particle diameter" as used herein
refers to the particle diameter of a particle formed by the
agglomeration of primary particles (secondary particle). The
particle diameter is a value for a volume particle diameter when a
cumulative frequency in the cumulative distribution function of
volume particle diameters obtained from a dynamic light scattering
particle diameter distribution-measuring apparatus (DLS) reaches
50% of the entirety.
[0045] (Basic Compound)
[0046] In the embodiment of the present invention, the basic
compound in the fine particle dispersion liquid containing tantalum
oxide fine particles is a component for reducing the crystallite
size of each of the tantalum oxide fine particles. Examples of the
basic compound used in the embodiment of the present invention
include: ammonia (including an aqueous solution of ammonia);
organic amine compounds; hydroxides of alkali metals and alkaline
earth metals such as sodium hydroxide and potassium hydroxide; and
alkoxides of alkali metals such as sodium methoxide and sodium
ethoxide. Of those, the organic amine compounds are particularly
preferred.
[0047] Here, the "organic amine compound" refers to an organic
compound having a nitrogen atom. Examples of the organic amine
compound include an alkylamine, an alkanolamine, an arylamine, a
heterocyclic amine, and an alkoxyamine. Examples of the alkylamine
include alkylamines each having 1 to 10 carbon atoms such as
methylamine, ethylamine, propylamine, butylamine, hexylamine,
octylamine, N,N-dimethylamine, N,N-diethylamine, N,N-dipropylamine,
N,N-dibutylamine, trimethylamine, triethylamine, tripropylamine,
and tributylamine. Examples of the alkanolamine include
2-(2-aminoethoxy)ethanol. Examples of the arylamine include
aniline. Examples of the heterocyclic amine include pyridine.
[0048] As the basic compound, preferred is at least one basic
compound selected from triethylamine, butylamine, N,N-dibutylamine,
aniline, pyridine, tetramethylethylenediamine, and
2-(2-aminoethoxy)ethanol. Of those, pyridine is more preferred.
This is because, when pyridine is used, an effect of reducing the
crystallite size of each of the tantalum oxide fine particles
through a dispersion treatment is large.
[0049] It should be noted that one kind of the above-mentioned
basic compounds may be used alone or two or more kinds thereof may
be used as a mixture.
[0050] (Organic Solvent)
[0051] Examples of the organic solvent included in the fine
particle dispersion liquid containing tantalum oxide fine particles
in this embodiment include: alcohols such as methanol, ethanol,
n-propyl alcohol, i-propyl alcohol, n-butanol, and i-butanol;
aliphatic hydrocarbons such as pentane, hexane, heptane, decane,
and cyclohexane; aromatic hydrocarbons such as toluene and xylene;
ethers such as diethyl ether, tetrahydrofuran, and 1,4-dioxane;
ketones such as dimethyl ketone, methyl ethyl ketone, and acetone;
esters such as ethyl acetate, and butyl acetate; and a
thermosetting monomer and/or a photocurable monomer. As one or both
of the thermosetting monomer and the photocurable monomer, there
are given (meth)acryl monomers such as methyl acrylate, methyl
methacrylate, and benzyl methacrylate, and epoxy monomers. In
addition, two or more kinds of organic solvents may be mixed. The
organic solvent is preferably at least one of tetrahydrofuran and
methyl methacrylate.
[0052] As can be seen from the examples of the organic solvent, the
organic solvent in the fine particle dispersion liquid containing
tantalum oxide fine particles in the embodiment of the present
invention, for example, at least one of a thermosetting monomer and
a photocurable monomer can be used as a resin serving as a
component for a tantalum oxide fine particle-resin composite in
another embodiment of the present invention to be described later
as well. As a result, the tantalum oxide fine particle-resin
composite in the embodiment of the present invention can be
obtained by adding one or both of a thermal polymerization
initiator and a photopolymerization initiator to the fine particle
dispersion liquid containing tantalum oxide fine particles and
curing the mixture.
[0053] (Surface Modifier)
[0054] In the embodiment of the present invention, the surface
modifier in the fine particle dispersion liquid containing tantalum
oxide fine particles covers each of the tantalum oxide fine
particles each having a small crystallite size in order that the
tantalum oxide fine particles may be uniformly and stably dispersed
in a resin. At least one of a silane coupling agent and a
metal-based coupling agent can be used as the surface modifier used
in the present invention. Of those, the silane coupling agent is
particularly preferred from the viewpoints of, for example, ease of
use and a cost. The term "silane coupling agent" as used herein
refers to a hydrolyzable silane compound having such a structure
that an organic substituent having affinity or reactivity for an
organic substance is chemically bonded to a hydrolyzable silyl
group having affinity or reactivity for an inorganic material.
[0055] In this embodiment, the silane coupling agent is not
particularly limited as long as the silane coupling agent can be
chemically bonded to a hydroxyl group on the surface of each of the
tantalum oxide fine particles to exert a surface treatment
function. Examples of the silane coupling agent include
vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriphenoxysilane,
p-styryltrimethoxysilane, p-styryltriethoxysilane,
p-styryltriphenoxysilane, 3-acryloxypropyltrimethoxysilane,
3-acryloxypropyltriethoxysilane, 3-acryloxypropyltriphenoxysilane,
3-methacryloxypropyltrimethoxysilane,
3-methacryloxypropyltriethoxysilane,
3-methacryloxypropyltriphenoxysilane,
3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane,
3-mercaptopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane,
allyltrimethoxysilane, allyltriethoxysilane, allyltriphenoxysilane,
methyltrimethoxysilane, dimethyldimethoxysilane,
trimethylmethoxysilane, n-propyltrimethoxysilane,
n-butyltriethoxysilane, n-hexyltrimethoxysilane,
n-hexyltriethoxysilane, n-octyltriethoxysilane,
n-decyltrimethoxysilane, phenyltrimethoxysilane, and
diphenyldimethoxysilane. In addition, two or more kinds of surface
modifiers may be used as a mixture. The surface modifier is
preferably 3-methacryloxypropyltriethoxysilane.
[0056] In this embodiment, examples of the metal-based coupling
agent include a titanate coupling agent, an aluminate coupling
agent, and a zirconate coupling agent. Examples of the titanate
coupling agent include isopropoxytitanium tristearate,
triisopropoxytitanium isostearate, isopropoxytitanium tripalmitate,
and isopropoxytitanium trimyristate. Examples of the aluminate
coupling agent include acetoalkoxyaluminum diisopropylate.
[0057] The kind of the silane coupling agent used in the present
invention to be described later can be appropriately selected
depending on the kind of the organic solvent. For example, a silane
coupling agent having a solubility parameter close to that of the
organic solvent is preferably used.
[0058] (Tantalum Oxide Fine Particle-Resin Composite)
[0059] The tantalum oxide fine particle-resin composite in another
embodiment of the present invention is obtained from a fine
particle dispersion liquid containing tantalum oxide fine
particles. The phrase "obtained from" as used herein refers to a
state in which the composite is obtained by a method of producing a
tantalum oxide fine particle-resin composite to be described later.
Specific examples of the method include: a method involving
polymerizing the fine particle dispersion liquid containing
tantalum oxide fine particles without any treatment; a method
involving mixing the fine particle dispersion liquid containing
tantalum oxide fine particles and a resin, and removing the organic
solvent; and a method involving taking a tantalum oxide powder out
of the tantalum oxide dispersion liquid, and melting and kneading
the powder with the resin.
[0060] A fine particle-resin composite 103 according to the
embodiment of the present invention has the tantalum oxide fine
particles 102 and a resin 101 (FIG. 2). As illustrated in the
figure, the tantalum oxide fine particles 102 are preferably
dispersed in the resin 101 in a uniform fashion because the
transparency of the fine particle-resin composite 103 is improved.
It should be noted that any one of the materials listed in the
following item (Resin) can be used as the resin 101.
[0061] (Method of Producing Tantalum Oxide Fine Particle-Resin
Composite)
[0062] The tantalum oxide fine particle-resin composite can be
produced with the tantalum oxide fine particles or the fine
particle dispersion liquid containing tantalum oxide fine particles
obtained by the production method in the embodiment of the present
invention. Although a method of producing the tantalum oxide fine
particle-resin composite is not particularly limited, the
production can be performed by any one of the methods listed below
selected depending on a material to be used and a purpose.
[0063] When, for example, a curable monomer is used as the organic
solvent in the fine particle dispersion liquid containing tantalum
oxide fine particles in the embodiment of the present invention,
the tantalum oxide fine particle-resin composite in the embodiment
of the present invention can be obtained by adding a step involving
adding a polymerization initiator corresponding to the curable
monomer and curing the mixture. As described above, a tantalum
oxide fine particle-resin composite having high transparency can be
easily produced by integrating the method of producing a fine
particle dispersion liquid containing tantalum oxide fine particles
and the method of producing a tantalum oxide fine particle-resin
composite. In addition, the resultant tantalum oxide fine
particle-resin composite may have a higher refractive index than
that of the resin alone because the composite has tantalum oxide
fine particles having high refractive indices.
[0064] The term "curable monomer" as used herein refers to one or
both of a thermosetting monomer and a photocurable monomer, and the
term "corresponding polymerization initiator" as used herein refers
to one or both of a thermal polymerization initiator and a
photopolymerization initiator.
[0065] The curable monomer cures the fine particle dispersion
liquid containing tantalum oxide fine particles in the presence of
a polymerization initiator by the application of an active energy
ray such as ultraviolet light or a visible light ray or heating, or
a combination of the application and the heating. As a result, the
tantalum oxide fine particle-resin composite can be obtained.
[0066] Examples of the polymerization initiator include: a
photopolymerization initiator that generates a radical by the
application of an active energy ray such as ultraviolet light or a
visible light ray; and a thermal polymerization initiator that
generates a radical by heating. The photopolymerization initiator
and the thermal polymerization initiator can be used in
combination.
[0067] As the photopolymerization initiator, there may be used a
known compound known to be usable in the application. Examples of
the compound include benzophenone, benzoin methyl ether, benzoin
propyl ether, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl
ketone, 2,6-dimethylbenzoyldiphenylphosphine oxide, and
2,4,6-trimethylbenzoyldiphenylphosphine oxide. One kind of those
photopolymerization initiators may be used alone or two or more
kinds thereof may be used in combination.
[0068] The photopolymerization initiator is typically used in an
amount of 0.001 part by weight to 5 parts by weight with respect to
100 parts by weight of the curable monomer.
[0069] As the thermal polymerization initiator, there may be used a
known compound known to be usable in the application. Examples of
the compound include dicumyl peroxide, di-t-butyl peroxide, t-butyl
peroxybenzoate, and t-butyl hydroperoxide. One kind of those
thermal polymerization initiators may be used alone or two or more
kinds thereof may be used in combination.
[0070] The thermal polymerization initiator is typically used in an
amount of 0.1 part by weight to 10 parts by weight with respect to
100 parts by weight of the curable monomer.
[0071] In addition, another example of the production method
includes the steps of: mixing the fine particle dispersion liquid
containing tantalum oxide fine particles and the resin or a resin
solution to prepare a tantalum oxide fine particle/resin mixed
liquid; and removing the organic solvent from the tantalum oxide
fine particle/resin mixed liquid.
[0072] Another example of the production method includes the steps
of: obtaining a tantalum oxide fine particle powder having a
crystallite size of 10 nm or less and covered with the surface
modifier from the fine particle dispersion liquid containing
tantalum oxide fine particles; and melting and kneading the
tantalum oxide fine particle powder and the resin.
[0073] (Resin)
[0074] Although the resin in which the tantalum oxide fine
particles are dispersed is not particularly limited as long as the
resin is a transparent resin material to be generally used as an
optical material, the resin is preferably an acrylic resin, a
cyclic olefin resin, a polycarbonate resin, a polyester resin, a
polyether resin, a polyamide resin, or a polyimide resin. The resin
is used at a ratio of preferably 30 wt % or more to 20,000 wt % or
less, more preferably 100 wt % or more to 2000 wt % or less with
respect to the tantalum oxide fine particle powder.
[0075] Hereinafter, examples are given for describing the present
invention in detail. However, the present invention is not limited
to these examples.
Example 1
Method of Measuring Crystallite Size of Tantalum Oxide Fine
Particle
[0076] The crystallite size of each of tantalum oxide fine
particles of this example is a value D(110) calculated from the
X-ray diffraction peak of the (110) surface of the tantalum oxide
fine particle obtained with an XRD (RINT2100 manufactured by Rigaku
Corporation) by using Debye-Scherrer's equation (Eq. 1) described
below:
D(110)=K*.lamda./.beta. cos .theta. (Eq. 1)
[0077] where D(110) represents a crystallite size (crystallite
size), K=0.9, .lamda.Cu-K.alpha.1=0.154056 nm, and represents the
half width of the diffraction peak.
[0078] (Method of Measuring Volume-Average Particle Diameter of
Tantalum Oxide Fine Particle)
[0079] The volume-average particle diameter of each of the tantalum
oxide fine particles of this example was measured with a dynamic
light scattering particle diameter distribution-measuring apparatus
(ZETASIZER Nano-S manufactured by Malvern Instruments Ltd.).
[0080] (Method of Measuring Haze Ratio of Fine Particle Dispersion
Liquid Containing Tantalum Oxide Fine Particles)
[0081] The haze ratio of a fine particle dispersion liquid
containing the tantalum oxide fine particles of this example was
measured as described below. A 10-wt % solution of the tantalum
oxide fine particles was prepared, and then its haze ratio was
measured with a turbidity meter (NDH-2000 manufactured by NIPPON
DENSHOKU INDUSTRIES CO., LTD.). A quartz cell having an optical
path length of 1 cm was used as a cell. When the solution had a
haze ratio of 10% or less, the solution was judged as having high
transparency.
[0082] (Evaluation for Dispersibility)
[0083] A metal oxide fine particle dispersion liquid was evaluated
for its dispersibility by observing the dispersion liquid with the
eyes after a lapse of 24 hours from a wet dispersion treatment. The
dispersion liquid in which a metal oxide was uniformly dispersed
without sedimenting was judged as being GOOD, and the dispersion
liquid in which the metal oxide sedimented but was not dispersed
was judged as being NG.
[0084] (Method of Producing Fine Particle Dispersion Liquid
Containing Tantalum Oxide Fine Particles)
[0085] Formulation
TABLE-US-00001 Tantalum oxide fine particles each having 3.1 parts
by weight a crystallite size of 20 nm
3-methacryloxypropyltriethoxysilane 3.1 parts by weight
Tetrahydrofuran 24.9 parts by weight Triethylamine 0.6 part by
weight
[0086] A mixture of the above-mentioned components was added to a
100-cc vessel, and was then subjected to a pretreatment with a bead
mill dispersing machine (UAM-015 manufactured by IMEX Co., Ltd.) at
a number of revolutions of 650 rpm for 10 minutes. After the
pretreatment, 104 parts by weight of zirconia beads each having a
diameter of 30 .mu.m were further added to the mixture (at a
filling factor of 50%), and then the whole was subjected to a
treatment at a number of revolutions of 1600 rpm for 360 minutes.
The zirconia beads were removed from the resultant slurry by
filtration. Thus, a fine particle dispersion liquid containing
tantalum oxide fine particles where the tantalum oxide fine
particles were dispersed in tetrahydrofuran was obtained. Tantalum
oxide in the resultant fine particle dispersion liquid containing
the tantalum oxide fine particles had a crystallite size of 5 nm
and a volume-average particle diameter of 11 nm, and hence the
crystallite size of tantalum oxide after the dispersion became
smaller than the crystallite size before the dispersion. In
addition, the dispersion liquid had a haze ratio of 7%, and hence
its transparency was high.
[0087] FIG. 1 shows a TEM photograph of the tantalum oxide fine
particles in the fine particle dispersion liquid containing the
tantalum oxide fine particles produced in Example 1. As can be seen
from the figure, tantalum oxide fine particles each having a
particle diameter of about 3 nm or more to 10 nm or less are
obtained, and the particle diameter coincides well with the
crystallite size calculated from the result of the XRD.
Example 2
[0088] The same operations as those of Example 1 were performed
except that the amount of triethylamine was changed to 0.3 part by
weight. Tantalum oxide in the resultant fine particle dispersion
liquid containing the tantalum oxide fine particles had a
crystallite size of 5 nm and a volume-average particle diameter of
13 nm, and hence the crystallite size of tantalum oxide after the
dispersion became smaller than the crystallite size of the raw
material. In addition, the dispersion liquid had a haze ratio of
7%, and hence its transparency was high.
Example 3
[0089] The same operations as those of Example 1 were performed
except that the amount of triethylamine was changed to 1.2 parts by
weight. Tantalum oxide in the resultant fine particle dispersion
liquid containing the tantalum oxide fine particles had a
crystallite size of 4 nm and a volume-average particle diameter of
13 nm, and hence the crystallite size of tantalum oxide after the
dispersion became smaller than the crystallite size of the raw
material. In addition, the dispersion liquid had a haze ratio of
7%, and hence its transparency was high.
Example 4
[0090] The same operations as those of Example 1 were performed
except that tantalum oxide fine particles each having a crystallite
size of 50 nm were used instead of the tantalum oxide fine
particles each having a crystallite size of 20 nm. Tantalum oxide
in the resultant fine particle dispersion liquid containing the
tantalum oxide fine particles had a crystallite size of 5 nm and a
volume-average particle diameter of 10 nm, and hence the
crystallite size of tantalum oxide after the dispersion became
smaller than the crystallite size of the raw material. In addition,
the dispersion liquid had a haze ratio of 6%, and hence its
transparency was high.
Example 5
[0091] The same operations as those of Example 1 were performed
except that triethylamine was changed to n-butylamine. Tantalum
oxide in the resultant fine particle dispersion liquid containing
the tantalum oxide fine particles had a crystallite size of 3 nm
and a volume-average particle diameter of 12 nm, and hence the
crystallite size of tantalum oxide after the dispersion became
smaller than the crystallite size of the raw material. In addition,
the dispersion liquid had a haze ratio of 7%, and hence its
transparency was high.
Example 6
[0092] The same operations as those of Example 1 were performed
except that triethylamine was changed to N,N-dibutylamine. Tantalum
oxide in the resultant fine particle dispersion liquid containing
the tantalum oxide fine particles had a crystallite size of 3 nm
and a volume-average particle diameter of 11 nm, and hence the
crystallite size of tantalum oxide after the dispersion became
smaller than the crystallite size of the raw material. In addition,
the dispersion liquid had a haze ratio of 5%, and hence its
transparency was high.
Example 7
[0093] The same operations as those of Example 1 were performed
except that triethylamine was changed to aniline. Tantalum oxide in
the resultant fine particle dispersion liquid containing the
tantalum oxide fine particles had a crystallite size of 5 nm and a
volume-average particle diameter of 13 nm, and hence the
crystallite size of tantalum oxide after the dispersion became
smaller than the crystallite size of the raw material. In addition,
the dispersion liquid had a haze ratio of 7%, and hence its
transparency was high.
Example 8
[0094] The same operations as those of Example 1 were performed
except that triethylamine was changed to pyridine. Tantalum oxide
in the resultant fine particle dispersion liquid containing the
tantalum oxide fine particles had a crystallite size of 2 nm and a
volume-average particle diameter of 9 nm, and hence the crystallite
size of tantalum oxide after the dispersion became smaller than the
crystallite size of the raw material. In addition, the dispersion
liquid had a haze ratio of 5%, and hence its transparency was
high.
Example 9
[0095] The same operations as those of Example 1 were performed
except that triethylamine was changed to
tetramethylethylenediamine. Tantalum oxide in the resultant fine
particle dispersion liquid containing the tantalum oxide fine
particles had a crystallite size of 4 nm and a volume-average
particle diameter of 12 nm, and hence the crystallite size of
tantalum oxide after the dispersion became smaller than the
crystallite size of the raw material. In addition, the dispersion
liquid had a haze ratio of 7%, and hence its transparency was
high.
Example 10
[0096] The same operations as those of Example 1 were performed
except that triethylamine was changed to 2-(2-aminoethoxy)ethanol.
Tantalum oxide in the resultant fine particle dispersion liquid
containing the tantalum oxide fine particles had a crystallite size
of 5 nm and a volume-average particle diameter of 13 nm, and hence
the crystallite size of tantalum oxide after the dispersion became
smaller than the crystallite size of the raw material. In addition,
the dispersion liquid had a haze ratio of 7%, and hence its
transparency was high.
Example 11
[0097] The same operations as those of Example 1 were performed
except that the bead mill dispersion treatment time was changed to
1440 minutes. Tantalum oxide in the resultant fine particle
dispersion liquid containing the tantalum oxide fine particles had
a crystallite size of 3 nm and a volume-average particle diameter
of 10 nm, and hence the crystallite size of tantalum oxide after
the dispersion became smaller than the crystallite size of the raw
material. In addition, the dispersion liquid had a haze ratio of
5%, and hence its transparency was high.
Example 12
[0098] The same operations as those of Example 1 were performed
except that tetrahydrofuran was changed to methyl methacrylate.
Tantalum oxide in the resultant fine particle dispersion liquid
containing the tantalum oxide fine particles had a crystallite size
of 5 nm and a volume-average particle diameter of 9 nm, and hence
the crystallite size of tantalum oxide after the dispersion became
smaller than the crystallite size of the raw material. In addition,
the dispersion liquid had a haze ratio of 5%, and hence its
transparency was high.
Comparative Example 1
[0099] The same operations as those of Example 1 were performed
except that triethylamine was not added. Tantalum oxide in the
resultant fine particle dispersion liquid containing the tantalum
oxide fine particles had a crystallite size of 20 nm and a
volume-average particle diameter of 36 nm, and hence such an effect
that the crystallite size after the dispersion became smaller than
the crystallite size of the raw material was not obtained. In
addition, the dispersion liquid had a haze ratio of 26%, and was
opaque.
Comparative Example 2
[0100] The same operations as those of Example 1 were performed
except that 3-methacryloxypropyltriethoxysilane was not added. The
tantalum oxide fine particles retained an agglomerated state, and
were not dispersed in tetrahydrofuran. In addition, such an effect
that the crystallite size after the stirring became smaller than
the crystallite size of the raw material was not obtained.
Comparative Example 3
[0101] Stirring was performed with a stirrer for 1440 minutes
instead of the bead mill dispersion in Example 1. The tantalum
oxide fine particles retained an agglomerated state, and were not
dispersed in tetrahydrofuran. In addition, such an effect that the
crystallite size after the stirring became smaller than the
crystallite size of the raw material was not obtained.
Comparative Example 4
[0102] The same operations as those of Example 1 were performed
except that .gamma.-alumina fine particles each having a
crystallite size of 7 nm were used instead of the tantalum oxide
fine particles each having a crystallite size of 20 nm. As a
result, a .gamma.-alumina fine particle dispersion liquid where the
.gamma.-alumina fine particles were dispersed in tetrahydrofuran
was obtained. .gamma.-Alumina in the resultant .gamma.-alumina fine
particle dispersion liquid had a crystallite size of 7 nm and a
volume-average particle diameter of 14 nm. In addition, the
dispersion liquid had a haze ratio of 10%, and hence its
transparency was high. However, such an effect that the crystallite
size after the dispersion became smaller than the crystallite size
of the raw material was not obtained.
Comparative Example 5
[0103] The same operations as those of Example 1 were performed
except that zinc oxide fine particles each having a crystallite
size of 30 nm were used instead of the tantalum oxide fine
particles each having a crystallite size of 20 nm. The zinc oxide
fine particles were not uniformly dispersed in tetrahydrofuran. In
addition, such an effect that the crystallite size after the bead
mill dispersion treatment became smaller than the crystallite size
of the raw material was not obtained.
Comparative Example 6
[0104] The same operations as those of Example 1 were performed
except that titanium oxide fine particles each having a crystallite
size of 15 nm were used instead of the tantalum oxide fine
particles each having a crystallite size of 10 nm. The titanium
oxide fine particles were not uniformly dispersed in
tetrahydrofuran. In addition, such an effect that the crystallite
size after the bead mill dispersion treatment became smaller than
the crystallite size of the raw material was not obtained.
[0105] As can be seen from the results of the foregoing examples
and comparative examples, the acquisition of a fine particle
dispersion liquid containing tantalum oxide fine particles each
having a small crystallite size requires a dispersion method by
which a strong shear is applied to a fine particle such as bead
mill dispersion, the presence of a basic compound, and the presence
of a surface modifier. It can also be seen from the results that
the phenomenon is a phenomenon peculiar to tantalum oxide.
[0106] As can be seen from the results of the foregoing examples
and comparative examples, the presence of a basic compound is
important in obtaining a fine particle dispersion liquid containing
tantalum oxide fine particles each having a small crystallite size,
and the fact that the presence is important is a phenomenon
peculiar to tantalum oxide. It can also be seen from the results
that uniform dispersion of the tantalum oxide fine particles in an
organic solvent requires the presence of a surface modifier. Table
1 summarizes the foregoing results.
TABLE-US-00002 TABLE 1 Raw material metal oxide (crystallite size)
Basic compound Surface modifier Organic solvent Example 1 3.1 parts
by weight 0.6 part by weight 3.1 parts by weight 24.9 parts by
weight of Ta.sub.2O.sub.5 (20 nm) of triethylamine of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Example 2
3.1 parts by weight 0.3 part by weight 3.1 parts by weight 24.9
parts by weight of Ta.sub.2O.sub.5 (20 nm) of triethylamine of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Example 3
3.1 parts by weight 1.2 parts by weight 3.1 parts by weight 24.9
parts by weight of Ta.sub.2O.sub.5 (20 nm) of triethylamine of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Example 4
3.1 parts by weight 0.6 part by weight 3.1 parts by weight 24.9
parts by weight of Ta.sub.2O.sub.5 (50 nm) of triethylamine of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Example 5
3.1 parts by weight 0.6 part by weight 3.1 parts by weight 24.9
parts by weight of Ta.sub.2O.sub.5 (20 nm) of butylamine of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Example 6
3.1 parts by weight 0.6 part by weight 3.1 parts by weight 24.9
parts by weight of Ta.sub.2O.sub.5 (20 nm) of N,N-dibutylamine of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Example 7
3.1 parts by weight 0.6 part by weight 3.1 parts by weight 24.9
parts by weight of Ta.sub.2O.sub.5 (20 nm) of aniline of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Example 8
3.1 parts by weight 0.6 part by weight 3.1 parts by weight 24.9
parts by weight of Ta.sub.2O.sub.5 (20 nm) of pyridine of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Example 9
3.1 parts by weight 0.6 part by weight 3.1 parts by weight 24.9
parts by weight of Ta.sub.2O.sub.5 (20 nm) of
tetramethylethylenediamine of 3-methacryloxypropyltriethoxysilane
of tetrahydrofuran Example 10 3.1 parts by weight 0.6 part by
weight 3.1 parts by weight 24.9 parts by weight of Ta.sub.2O.sub.5
(20 nm) of 2-(2-aminoethoxy)ethanol of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Example 11
3.1 parts by weight 0.6 part by weight 3.1 parts by weight 24.9
parts by weight of Ta.sub.2O.sub.5 (20 nm) of triethylamine of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Example 12
3.1 parts by weight 0.6 part by weight 3.1 parts by weight 24.9
parts by weight of Ta.sub.2O.sub.5 (20 nm) of triethylamine of
3-methacryloxypropyltriethoxysilane of methyl methacrylate
Comparative 3.1 parts by weight None 3.1 parts by weight 24.9 parts
by weight Example 1 of Ta.sub.2O.sub.5 (20 nm) of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Comparative
3.1 parts by weight 0.6 part by weight None 24.9 parts by weight
Example 2 of Ta.sub.2O.sub.5 (20 nm) of triethylamine of
tetrahydrofuran Comparative 3.1 parts by weight 0.6 part by weight
3.1 parts by weight 24.9 parts by weight Example 3 of
Ta.sub.2O.sub.5 (20 nm) of triethylamine of
3-methacryloxypropyltriethoxysilane of tetrahydrofuran Comparative
3.1 parts by weight 0.6 part by weight 3.1 parts by weight 24.9
parts by weight Example 4 of Al.sub.2O.sub.3 (7 nm) of
triethylamine of 3-methacryloxypropyltriethoxysilane of
tetrahydrofuran Comparative 3.1 parts by weight 0.6 part by weight
3.1 parts by weight 24.9 parts by weight Example 5 of ZnO (30 nm)
of triethylamine of 3-methacryloxypropyltriethoxysilane of
tetrahydrofuran Comparative 3.1 parts by weight 0.6 part by weight
3.1 parts by weight 24.9 parts by weight Example 6 of TiO.sub.2 (15
nm) of triethylamine of 3-methacryloxypropyltriethoxysilane of
tetrahydrofuran Crystallite Volume-average Dispersion size after
particle diameter Haze ratio treatment dispersion after dispersion
of dispersion time Dispersibility treatment treatment liquid
Example 1 360 minutes GOOD 5 nm 11 nm 6% Example 2 360 minutes GOOD
5 nm 13 nm 7% Example 3 360 minutes GOOD 4 nm 13 nm 7% Example 4
360 minutes GOOD 5 nm 10 nm 6% Example 5 360 minutes GOOD 3 nm 12
nm 7% Example 6 360 minutes GOOD 3 nm 11 nm 5% Example 7 360
minutes GOOD 5 nm 13 nm 7% Example 8 360 minutes GOOD 2 nm 9 nm 5%
Example 9 360 minutes GOOD 4 nm 12 nm 7% Example 10 360 minutes
GOOD 5 nm 13 nm 7% Example 11 1440 minutes GOOD 3 nm 10 nm 5%
Example 12 360 minutes GOOD 5 nm 9 nm 5% Comparative 360 minutes
GOOD 20 nm 36 nm 26% Example 1 Comparative 360 minutes NG 20 nm
Unmeasurable -- Example 2 Comparative Stirring with NG 20 nm
Unmeasurable -- Example 3 stirrer for 1440 minutes Comparative 360
minutes GOOD 7 nm 14 nm 10% Example 4 Comparative 360 minutes NG 30
nm Unmeasurable -- Example 5 Comparative 360 minutes NG 15 nm
Unmeasurable -- Example 6
[0107] The tantalum oxide particle dispersion liquid obtained by
the production method of the present invention can find
applications in the fields of, for example, optical materials,
electronic part materials, and recording materials.
[0108] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0109] This application claims the benefit of Japanese Patent
Application No. 2009-251486, filed Oct. 30, 2009, which is hereby
incorporated by reference herein in its entirety.
* * * * *