U.S. patent application number 11/365558 was filed with the patent office on 2006-11-23 for transparent conductive film and coating composition therefor.
This patent application is currently assigned to Bussan Nanotech Research Institute Inc.. Invention is credited to Tadashi Ashida, Koichi Handa, Toshiki Natori, Jiayi Shan, Subiantoro, Takayuki Tsukada.
Application Number | 20060263588 11/365558 |
Document ID | / |
Family ID | 37307730 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060263588 |
Kind Code |
A1 |
Handa; Koichi ; et
al. |
November 23, 2006 |
Transparent conductive film and coating composition therefor
Abstract
The disclosed is a transparent conductive film that includes a
matrix and carbon fibrous structures added to the matrix, wherein
the carbon fibrous structures comprise carbon fibers, each having
an outside diameter of 15-100 nm, and wherein the carbon fibrous
structures each comprise a granular part at which two or more
carbon fibers are bound to each other, and wherein the granular
part is concurrently produced in a growth process for the carbon
fibers. When the transparent conductive film is formed at a
thickness of 0.1-5 .mu.m on a glass substrate, it shows a surface
resistivity of not more than
1.0.times.10.sup.12.OMEGA./.quadrature., and a total light
transmittance of not less than 30%. A coating composition for the
conductive transparent film is prepared by using a media mill
equipped with beads having an average diameter of 0.05-1.5 mm to
disperse the carbon fibrous structures into the liquid resinous
composition.
Inventors: |
Handa; Koichi; (Tokyo,
JP) ; Subiantoro;; (Tokyo, JP) ; Tsukada;
Takayuki; (Tokyo, JP) ; Shan; Jiayi; (Tokyo,
JP) ; Ashida; Tadashi; (Tokyo, JP) ; Natori;
Toshiki; (Tokyo, JP) |
Correspondence
Address: |
OSHA LIANG L.L.P.
1221 MCKINNEY STREET
SUITE 2800
HOUSTON
TX
77010
US
|
Assignee: |
Bussan Nanotech Research Institute
Inc.
Tokyo
JP
Parker Corporation
Tokyo
JP
|
Family ID: |
37307730 |
Appl. No.: |
11/365558 |
Filed: |
February 28, 2006 |
Current U.S.
Class: |
428/292.1 |
Current CPC
Class: |
C01B 32/168 20170801;
H01B 1/24 20130101; Y10T 428/249924 20150401; C08J 5/042 20130101;
C01B 2202/34 20130101; B82Y 30/00 20130101; B82Y 40/00 20130101;
C01B 2202/06 20130101; C01B 2202/36 20130101; C08K 7/06
20130101 |
Class at
Publication: |
428/292.1 |
International
Class: |
D04H 1/00 20060101
D04H001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2005 |
JP |
2005-132691 |
Claims
1. A transparent conductive film, comprising a matrix resin and
carbon fibrous structures added to the matrix, wherein the carbon
fibrous structures comprise carbon fibers, each having an outside
diameter of 15-100 nm, and wherein the carbon fibrous structures
each comprise a granular part at which two or more carbon fibers
are bound to each other, and wherein the granular part is produced
in a growth process for the carbon fibers.
2. The transparent conductive film according to claim 1, wherein
the carbon fibrous structures are added at an amount in the range
of 1 to 25 parts by weight based on 100 parts by weight of the
matrix.
3. The transparent conductive film according to claim 1, wherein
the transparent conductive film has a surface resistivity of not
more than 1.0.times.10.sup.12.OMEGA./.quadrature., and a total
light transmittance of not less than 30%, when the transparent
conductive film is formed at a thickness of 0.1-5 .mu.m on a glass
substrate.
4. A coating composition for a transparent conductive film,
comprising a liquid resinous composition and carbon fibrous
structures dispersed into the resinous composition, wherein the
carbon fibrous structures comprise carbon fibers each having an
outside diameter of 15-100 nm, and wherein the carbon fibrous
structures each comprise a granular part at which two or more
carbon fibers are bound to each other, and wherein the granular
part is produced in a growth process for the carbon fibers.
5. The coating composition according to claim 4, wherein the
resinous composition comprises a resin as a non-volatile
vehicle.
6. The coating composition according to claim 4, wherein the carbon
fibrous structures are added at an amount in the range of 1 to 25
parts by weight based on 100 parts by weight of the liquid resinous
composition.
7. The coating composition according to claim 4, wherein the
coating composition is prepared by using a media mill equipped with
beads having an average diameter of 0.05-1.5 mm to disperse the
carbon fibrous structures into the liquid resinous composition.
8. The coating composition according to claim 7, wherein the
coating composition is prepared by using a high-shear type
distributor prior to dispersing the carbon fibrous structures using
the media mill.
Description
CROSS REFERNCE TO RELATED APPLICATIONS
[0001] This claims priority of Japanese Patent Application No.
2005-132691, filed on Apr. 28, 2005, the disclosure of which,
including the specification, claims, drawings and summary, is
incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] This invention relates to a transparent conductive film and
a coating composition for the transparent conductive film. More
particularly, this invention relates to a transparent conductive
film that has a good transparency and a high conductivity, as well
as to a coating composition for forming the transparent conductive
film.
Background Art
[0004] Transparent conductive films have been utilized as electrode
materials for liquid crystal display devices, organic
electroluminescent (EL) devices, and various other electronic
devices. They have also been used for the purpose of removing
static electricity from transparent members in order to prevent
sticking of dusts to such members, through which viewing of the
other sides is desired, such as partitions of clean rooms and
inspection windows of various test equipment.
[0005] Inorganic acid type materials such as ITO, IZO, etc., and
metal evaporated films have been developed as transparent
conductive films in wide use. However, there are several
restrictions on these materials, such as difficulty in controlling
their electrical characteristics, and limited range of applicable
substrate materials.
[0006] Another type of conductive film whose conductivity is
imparted by particles of a certain material, such as metal, metal
oxide, carbon, etc., added to the matrix of the film is also known.
Furthermore, a transparent conductive resin board comprising long
carbon fibers blended with a thermoplastic resin that acts as a
matrix has been proposed in JP-2001-62952A and JP-2004-195993A.
Other transparent conductive resin boards have also been proposed
in JP-2004-230690A, wherein carbon nanotubes are added to a
thermoplastic resin under the condition that the carbon nanotubes
are dispersed in a mutually independent manner, or as bundles
wherein each bundle is composed of some carbon nanotubes and the
bundles are dispersed mutually independent of each other. The
related parts of JP-2001-62952A, JP-2004-195993A and
JP-2004-230690A are incorporated herein by reference.
[0007] In the transparent conductive resin boards shown in
JP-2001-62952A, JP-2004-195993A and JP-2004-230690A, however, it is
difficult to disperse the fibers uniformly throughout the
thermoplastic resin matrix since the long carbon fibers or carbon
nanotubes must be mixed in single-fiber form with the thermoplastic
resin matrix. Therefore, the resulting conductivity of the boards
can hardly be expected to be uniformly inplane. When kneading force
is increased in order to enhance the dispersibility of the carbon
fibers into the matrix, it occurs the problem that the fibers would
be cut into shreds. Consequently it is necessary to add more fibers
in order to achieve a predetermined conductivity. The increased
amount of fibers will result in a reduction of transparency of the
board.
BRIEF SUMMARY OF THE INVENTION
[0008] Therefore, this invention aims to provide a new transparent
conductive film and a coating composition therefor capable of
solving above mentioned problems in the arts. This invention also
aims to provide a transparent conductive film and a coating
composition therefor, which possesses improved and well
controllable electrical properties by adding a small amount of
additive or filler without damaging the characteristic of the
matrix, while maintaining a good transparency of the film.
[0009] As a result of diligent study for solving the above
problems, the inventors have found that the followings are
effective at improving the electrical properties of a matrix even
at a limited additive amount, and finally accomplished the present
invention:
[0010] To adapt carbon fibers having a diameter as small as
possible;
[0011] To make a sparse structure of the carbon fibers, in which
the fibers are bound to each other tightly so that the fibers do
not behave individually and their sparse state are sustained in the
resin matrix;
[0012] To adapt as carbon fibers per se ones which are designed to
have a minimum amount of defects; and
[0013] To use a particular dispersion treatment capable of
dispersing carbon fibrous structures throughout a matrix uniformly
without destroying the fibrous structures.
[0014] The present invention to solve the above mentioned problems
is, therefore, a transparent conductive film, which comprises a
matrix resin and carbon fibrous structures added to the matrix,
wherein the carbon fibrous structures are comprised of carbon
fibers each having an outside diameter of 15-100 nm, and wherein
each carbon fibrous structure further comprises a granular part at
which two or more carbon fibers are bound to each other in a state
that the concerned carbon fibers are outwardly elongated therefrom,
and wherein the granular part is produced in a growth process for
the carbon fibers.
[0015] In an embodiment of a transparent conductive film according
to the present invention, it is disclosed that carbon fibrous
structures are added to a matrix resin at an amount in the range of
1 to 25 parts by weight based on 100 parts by weight of the
matrix.
[0016] In another embodiment of a transparent conductive film
according to the present invention, it is disclosed that the
transparent conductive film has a surface resistivity of not more
than 1.0.times.10.sup.12.OMEGA./.quadrature., and a total light
transmittance of not less than 30%, when the transparent conductive
film is formed at a thickness of 0.1-5 .mu.m on a glass
substrate.
[0017] In another aspect, the present invention to solve the above
mentioned problems is a coating composition for a transparent
conductive film. The coating composition comprises a liquid
resinous composition, including a resin as a non-volatile vehicle,
and carbon fibrous structures dispersed into the resinous
composition, wherein the carbon fibrous structures are comprised of
carbon fibers each having an outside diameter of 15-100 nm, and
wherein each carbon fibrous structure further comprises a granular
part at which two or more carbon fibers are bound to each other in
a state that the concerned carbon fibers are outwardly elongated
therefrom, and wherein the granular part is produced in a growth
process for the carbon fibers.
[0018] In an embodiment of a coating composition for a transparent
conductive film according to the present invention, it is disclosed
that the carbon fibrous structures are added at an amount in the
range of 1 to 25 parts by weight based on 100 parts by weight of
the liquid resinous composition.
[0019] In another embodiment of a coating composition for a
transparent conductive film according to the present invention, it
is disclosed that the coating composition is prepared by using a
media mill equipped with beads having an average diameter of
0.05-1.5 mm to disperse carbon fibrous structures into a liquid
resinous composition.
[0020] In a further embodiment of a coating composition for a
transparent conductive film according to the present invention, it
is disclosed that the coating composition is prepared by using a
high-shear type distributor prior to the dispersion treatment using
the media mill.
[0021] According to embodiments of the present invention, each of
the carbon fibrous structures to be added to a matrix resin as an
electrical conductivity imparting agent has a specific
configuration in which some carbon fibers are bound to each other
tightly by a granular part produced in a growth process for the
carbon fibers wherein the concerned carbon fibers are outwardly
elongated from the granular part. Such carbon fibrous structures
can disperse easily into a matrix resin upon adding, while
maintaining their sparse structure. Even when they are added at a
small amount to the matrix, they can be distributed uniformly
throughout the matrix. Therefore, with respect to electrical
conductivity, it is possible to obtain good electrical conductive
paths throughout the matrix even with a small dosage of added
fibrous structures, thereby improving the electrical conductivity
adequately and controllably of the conductive film. With respect to
transparency of the film, a high degree of transparency can be
maintained since the carbon fibrous structures can be uniformly
distributed throughout the matrix.
[0022] Further, on preparing a coating composition for a
transparent conductive film according to the present invention,
using a media mill equipped with beads of a prescribed mean
diameter, it is possible to achieve a good and uniform dispersion
without adding any dispersion stabilizer such as a surfactant. In
this way, breakdown of the carbon fibrous structures is avoided,
and a transparent conductive film having good properties can be
prepared with ease.
[0023] In addition, by subjecting the mixture of resinous
composition and carbon fibrous structures to a dispersion treatment
using a high-shear type distributor before dispersion treatment
using a media mill, a more homogeneous distribution can be
attained, which, in turn, leads to improve film properties on
making the film film.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a transmission electron micrograph (TEM photo) of
an intermediate for the carbon fibrous structure, which is used for
a transparent conductive film according to embodiments of the
present invention;
[0025] FIGS. 2A and 2B are transmission electron micrographs (TEM)
of a carbon fibrous structure, which is used for a transparent
conductive film according to embodiments of the present
invention;
[0026] FIG. 3 is an X-ray diffraction chart of a carbon fibrous
structure and an intermediate of the carbon fibrous structure,
which are used for a transparent conductive film according to
embodiments of the present invention and an intermediate
thereof;
[0027] FIG. 4 is Raman spectra of a carbon fibrous structure and an
intermediate of the carbon fibrous structure, which is used for a
transparent conductive film according to embodiments of the present
invention and an intermediate thereof;
[0028] FIG. 5 is an optical microphotograph illustrating dispersion
condition of the carbon fibrous structures in an embodiment of a
transparent conductive film according to embodiments of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0029] The present invention will now be described in detail with
reference to some embodiments, which are disclosed only for the
purpose of facilitating the illustration and understanding of the
present invention, and are not to be construed as limiting.
[0030] A transparent conductive film according to embodiments of
the present invention is characterized by the inclusion and
dispersion of carbon fibrous structures in a thermosetting matrix
resin, wherein each of the carbon fibrous structures has a specific
configuration to be described later.
[0031] A carbon fibrous structure to be combined with a transparent
conductive film according to embodiments of the present invention
is, as shown in TEM photos of FIG. 2A and 2B, comprised of carbon
fibers each having an outside diameter of 15-100 nm, and wherein a
granular part at which several carbon fibers are bound to each
other, wherein the concerned carbon fibers are outwardly elongated
from the granular part.
[0032] The reason for ranging the outside diameter of a carbon
fiber between 15 nm and 100 nm is because when the outside diameter
of the carbon fiber is less than 15 nm, the cross-section of the
carbon fiber does not have a polygonal figure, as will be discussed
later. For a physical property of a carbon fiber, the more the
number of the carbon fibers increase per unit quantity and the
smaller the diameter it has, the longer its length in the axial
direction will be. Longer length and smaller diameter is generally
associated with an enhancement in electrical conductivity. Thus,
carbon fibrous structures having outside diameters exceeding 100 nm
is not preferred to use as conductivity imparting agent in a matrix
such as a resinous material, etc. Particularly, it is more
desirable for a carbon fiber to have a diameter in the range of
20-70 nm. Carbon fibers that have diameters within the preferred
range and tubular graphene sheets layered orthogonal to the axis,
i.e., being of the multilayer type, can have high bending stiffness
and ample elasticity. In other words, such carbon fibers would have
the property of being easy to restore to their original shapes
after undergoing any deformation. Therefore, they tend to take a
sparse structure in a matrix such as a resin after mixing with the
matrix material, even if they have been compressed.
[0033] Incidentally, annealing at a temperature of not less than
2400.degree. C. would cause the carbon fibers to form polygonal
cross-sections. Additionally, annealing also narrows the spacing
between the layered graphene sheets, which can increase the true
density of the carbon fibers from 1.89 g/cm.sup.3 to 2.1
g/cm.sup.3. Therefore, annealed carbon fibers can become denser and
have fewer defects in both the stacking direction and the surface
direction of the tubular graphene sheets which comprise a carbon
fiber, with the result that flexural rigidity (EI) is enhanced.
[0034] Additionally, it is preferable that the outside diameter of
a carbon fiber varies along the axial direction of the fiber.
Fibers not having certain diameters but having variable diameters
along their axial direction are expected to have a kind of
anchoring effect at the interface between the fiber and the matrix
material such as a resin, thus restraining migration of the carbon
fibrous structure in the matrix and improving the dispersion
stability.
[0035] Then, in a carbon fibrous structure according to embodiments
of the present invention, the carbon fibers would have
predetermined outside diameters, be configured three dimensionally,
and be bound to each other by a granular part produced in a growth
process for the carbon fibers, wherein the carbon fibers are
outwardly elongated from the granular part. Since the multitude of
carbon fibers are not only entangled with each other, but also
bound to each other tightly at the granular part, they do not
disperse as single fibers, but as bulky carbon fibrous structures
when added to the matrix such as resin. Since the carbon fibers are
bound together by a granular part, produced in the growth process
for the carbon fibers, in a carbon fibrous structure according to
embodiments of the present invention, the carbon fibrous structure
itself can have superior properties such as electrical property.
For instance, a carbon fibrous structure according to the present
invention exhibits an extremely small electrical resistance under a
certain pressed density, as compared with that of a simple
aggregate of carbon fibers and that of a carbon fibrous structure
in which the carbon fibers are fixed at the contacting points with
a carbonaceous material or carbonized the resultant carbon fibers
after their synthesis. Thus, when a carbon fibrous structure in
accordance with embodiments of the invention is added and
distributed into a matrix, it can form a good conductive path in
the matrix.
[0036] Further, although not specifically limited, it is preferred
that the diameter of the granular part is larger than the outside
diameter of a carbon fiber as shown in FIGS. 2A and 2B. When the
granular part (the binding site of the carbon fibers) has an amply
large particle diameter, the binding force between the outwardly
elongated carbon fibers and the granule is enhanced, and thus, even
when the carbon fibrous structures are exposed to a relatively high
shear stress upon blending into a matrix such as a resin, they can
be dispersed as three dimensionally structures into the matrix. The
"particle diameter of the granular part" used herein is the value
measured by assuming that the granular part is biding site of each
carbon fibers.
[0037] Further, a carbon fibrous structure to be used in the
present invention can have a bulky form, in which the carbon fibers
are sparsely configured since the carbon fibrous structure is
comprised of carbon fibers that are bound to each other by a
granular part, wherein the carbon fibers are outwardly elongated
from the granular part as mentioned above. Specifically, it is
desirable that the bulk density thereof is in the range of
0.0001-0.05 g/cm.sup.3, more preferably, 0.001-0.02 g/cm.sup.3.
When the bulk density exceeds 0.05 g/cm.sup.3, the improvement in
the physical properties of a matrix resin would be more difficult
to attain with a small dosage.
[0038] Further, a carbon fibrous structure to be used in the
present invention can itself have good electrical properties, since
the carbon fibers comprising the three dimensionally structure are
bound to each other by a granular part produced in a growth process
for the carbon fibers as mentioned above. For instance, it is
desirable that a carbon fibrous structure according to embodiments
of the present invention shows a particle's resistance of not more
than 0.02 .OMEGA.cm, as determined under a certain pressed density
(0.8 g/cm.sup.3), and more preferably, 0.001 to 0.010 .OMEGA.cm. If
the particle's resistance exceeds 0.02 .OMEGA.cm, it may be more
difficult to form a good conductive path when the structures are
added to a matrix resin.
[0039] In order to enhance the strength and electrical conductivity
of a carbon fibrous structure according to embodiments of the
present invention, it is desirable that the graphene sheets making
up the carbon fibers have a minimum number of defects, and more
specifically, for example, the I.sub.D/I.sub.G ratio of the carbon
fibers as determined by Raman spectroscopy is not more than 0.2,
more preferably, not more than 0.1. Incidentally, in Raman
spectroscopic analysis, if the sample is a large single-crystal
graphite, only the peak (G band) at 1580 cm.sup.-1 is observed.
When the crystals are of finite minute sizes or have any lattice
defects, a peak (D band) at 1360 cm.sup.-1 can appear. Therefore,
when the ratio between D band and G band
(R.dbd.I.sub.1360/I.sub.1580=I.sub.D/I.sub.G) is within the certain
value as mentioned above, it is possible to infer that there is
little defect in the graphene sheets.
[0040] Further, it is desirable that a carbon fibrous structure
according to embodiments of the present invention has a combustion
initiation temperature in air of not less than 750.degree. C.,
preferably, 800.degree. C.-900.degree. C. Such a high thermal
stability can be attributed to the facts that the fibers have very
little defect and have predetermined outside diameters.
[0041] It is not limited to, but a carbon fibrous structure of the
above desirable form may be prepared as follows.
[0042] Basically, an organic compound such as a hydrocarbon is
chemical thermally decomposed through the CVD process in the
presence of ultraminute particles of a transition metal as a
catalyst in order to obtain a fibrous structure (hereinafter
referred to as "intermediate"). The intermediate thus obtained is
then subjected to a high temperature heating treatment.
[0043] For raw material organic compounds, hydrocarbons such as
benzene, toluene, xylene; carbon monoxide (CO), and alcohols such
as ethanol may be used. It is preferable, but not limited, to use
as carbon sources at least two carbon compounds having different
decomposition temperatures. Incidentally, the phrase "at least two
carbon compounds" used herein does not only mean using two or more
kinds of raw materials, but also means using one kind of a raw
material that can effect a reaction such as the hydrodealkylation
of toluene or xylene during the course of synthesis reaction for
the fibrous structure to produce an intermediate, which can
function as at least two kinds of carbon compounds having different
decomposition temperatures in the subsequent thermal decomposition
process.
[0044] Inert gases such as argon, helium, xenon; and hydrogen may
be used as an atmospheric gas.
[0045] A mixture of transition metal such as iron, cobalt,
molybdenum; or transition metal compounds such as ferrocene, metal
acetate; and sulfur or a sulfur compound such as thiophene, ferric
sulfide; may be used as a catalyst.
[0046] The intermediate may be synthesized using a CVD process of
hydrocarbon or other compounds conventionally used in the art. A
typical CVD process includes the following steps: gasifying a
mixture of a raw material organic compound and a catalyst,
supplying the gasified mixture into a reaction furnace along with a
carrier gas such as hydrogen gas, etc., and performing thermal
decomposition at a temperature in the range of 800.degree.
C.-1300.degree. C. By following such a synthesis procedure, one
obtains an aggregate of several to several tens of centimeters in
size composed of plural carbon fibrous structures (intermediates),
each of which shows a sparse three dimensional configuration,
wherein fibers having 15-100 nm in outside diameter are bound to
each other by a granule that has grown around a catalyst particle
as the nucleus.
[0047] The thermal decomposition reactions of hydrocarbon raw
materials mainly occur on the surface of catalyst particles or on a
surface of a granule grown around a catalyst particle nucleus. When
recrystallization of carbons created from the decomposition
reaction progresses in a constant direction from the catalyst
particles or the granule, fibrous growth of carbon may be achieved.
To obtain a carbon fibrous structure according to embodiments of
the present invention, however, the balance between decomposition
rate and growing rate is varied intentionally. For instance, as
mentioned above, using as carbon sources at least two kinds of
carbon compounds having different decomposition temperatures may
allow the carboneous material to grow three dimensionally around a
granule as a centre, rather than growing in one dimensional
direction. Three dimensional growth of carbon fibers depends not
only on the balance between the decomposition rate and the growing
rate, but also on the crystal face's selectivity of a catalyst
particle, residence time within the reaction furnace, temperature
distribution in the furnace, etc., and the balance between the
decomposition rate and the growing rate is affected not only by the
kind of the carbon source as mentioned above, but also by the
reaction temperature, gas temperature, etc. In general, when the
growing rate is larger than the decomposition rate, the carbon
material tends to grow in fibrous configuration, whereas when the
decomposition rate is larger than the growing rate, the carbon
material tends to grow into peripheral directions of the catalyst
particle. Accordingly, by changing the balance between the
decomposition rate and the growing rate intentionally, it is
possible to control the growth of a carbon material in
multi-directions rather than in a certain single direction, and to
form a three dimensional structure according to embodiments of the
present invention.
[0048] In order to form the above mentioned three dimensional
configuration, wherein the fibers are bound to each other by a
granule, it is desirable to optimize the reaction compositions
(catalyst, etc.), the residence time in the reaction furnace, the
reaction temperature, the gas temperature, etc.
[0049] The intermediate obtained by heating the gaseous mixture of
a catalyst and hydrocarbons at a constant temperature in the range
of 800.degree. C.-1300.degree. C. typically takes a structure
resembling some patch-like sheets of carbon atoms laminated
together (and being still in half-raw or incomplete condition).
When analyzed with Raman spectroscopy, a large D band and many
defects are observed.
[0050] The intermediate thus obtained includes unreacted raw
materials, nonfibrous carbide, tar moiety and catalyst metal. In
order to remove such residues to produce the intended carbon
fibrous structure with few defects, the intermediate is subjected
to a high temperature heating treatment at 2400-3000.degree. C.
using a proper method.
[0051] For instance, the intermediate may be first heated at
800-1200.degree. C. to remove unreacted raw materials and volatile
flux such as tar moiety, and thereafter annealed at a high
temperature of 2400-3000.degree. C. to produce the intended
structure and to vaporize the catalyst metal that has been included
in the fiber concurrently. In this process, it may add a reducing
gas and carbon monoxide gas of a small amount into the inert gas
atmosphere to protect the material structure.
[0052] By annealing the intermediate at a temperature of
2400-3000.degree. C., the patch-like sheets of carbon atoms are
rearranged so as to associate mutually and form multiple graphene
sheet-like layers.
[0053] Either before or after such a high temperature heating
treatment, the aggregates may be crushed in order to obtain carbon
fibrous structures that have an area-based circle-equivalent mean
diameter of several centimeters. The obtained carbon fibrous
structures may then be pulverized in order to obtain carbon fibrous
structures that have a predetermined area-based circle-equivalent
mean diameter of 50-100 .mu.m. Pulverizing directly without
crushing is also permissible. Aggregates comprising plural carbon
fibrous structures according to embodiments of the present
invention may also be treated to adjust their shapes, sizes, or
bulk densities to ones suitable for using. More preferably, in
order to utilize effectively the structures formed from the
reaction described above, annealing should be performed on
structures that are in a state of low bulk density (i.e., the state
in which the fibers are extended as much as they can and the
voidage is amply large), which may contribute to improve the
electrical conductivity of a matrix resin.
[0054] Next, as resins to be used as a matrix of a transparent
conductive film according to embodiments of the present invention,
any of various thermoplastic resins and thermosetting resins, as
well as other natural resins or modified resins therefrom, for
example, may be used. Among them, a resin of thermosetting type may
be desirable from the stand point of easy film coating.
[0055] With respect to a transparent conductive film according to
embodiments of the present invention, the amount of carbon fibrous
structures to be mixed into a resin is not particularly limited.
For satisfactory good transparency and conductivity, however, it is
preferable in general that the carbon fibrous structures are added
and dispersed into the resin at an amount of 1-25 parts by weight
based on 100 parts by weight of the resin. A transparent conductive
film having a mixing amount as mentioned above would have a surface
resistivity of not more than
1.0.times.10.sup.12.OMEGA./.quadrature., and a total light
transmittance of not less than 30%, when the transparent conductive
film is formed at a thickness of 0.1-5 .mu.m on a glass substrate.
In addition, the haze of the transparent conductive film would
become not more than 30%.
[0056] When used in a particular application such as a transparent
electrode material, it is more preferable that carbon fibrous
structures are added and dispersed into a resin at an amount of
10-25 parts by weight based on 100 parts by weight of the resin. In
this case, a surface resistivity of
10.sup.1-10.sup.4.OMEGA./.quadrature., and a total light
transmittance of not less than 50% is expected. In another
particular use such as in anti-static window parts, it is more
preferable that carbon fibrous structures are added and dispersed
into a resin at an amount of 1-10 parts by weight based on 100
parts by weight of the resin. In this case, a surface resistivity
of 10.sup.4-10.sup.12.OMEGA./.quadrature., and a total light
transmittance of not less than 30% is expected.
[0057] A coating composition for preparing an aforementioned
transparent conductive film according to embodiments of the present
invention will be described below.
[0058] A coating composition according to embodiments of the
present invention comprises a liquid resinous composition including
a resin as a non-volatile vehicle, and carbon fibrous structures,
each having above mentioned specific structure dispersed into the
liquid resinous composition.
[0059] Carbon fibrous structures used in this coating composition
are the same as described above in detail.
[0060] A liquid resinous composition to be used in embodiments of
this invention may involve various types of liquid resinous
compositions, such as water- or oil-based coating compositions, ink
compositions, as well as other various coating compositions, in
which a resin as a non-volatile vehicle is dissolved in a solvent
or dispersed into a dispersant. As for the resin ingredient,
various organic compounds such as thermoplastic resins,
thermosetting resins, as well as natural resins and modified resins
thereof are usable. For example, acrylic type resins such as
aqueous acrylic, acrylic lacquer; ester type resins such as alkyd
resins, various modified alkyd resins, unsaturated polyesters;
melamin type resins; urethane type resins; epoxy type resins, and
other resins such as polyvinyl chloride, polyvinyl acetate,
polyvinyl alcohol, polystyrene, polyamide, phenol resin, furan
resin, xylene formaldehyde resin, urea resin, and etc., are
concretely examples, but these are not limited examples. Then,
depending on the kind of resin ingredients used, a liquid resinous
composition can be into different types such as baking type, cold
setting type, etc.
[0061] The liquid to be used as solvent or dispersion medium in a
liquid resin composition is also not particularly limited, and may
be selected properly in accordance with the kind of the resin
ingredients to be used. For example, as liquids, water; alcohols
such as methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl
alcohols, allyl alcohols; glycols or their derivatives such as
ethylene glycol, propylene glycol, diethylene glycol, polyethylene
glycols, polypropylene glycols, diethylene glycol monoethyl ether,
polypropylene glycol monoethyl ethers, polyethylene glycol
monoallyl ethers, polypropylene glycol monoallyl ethers; glycerol
or its derivatives such as glycerol, glycerol monoethyl ether,
glycerol monoallyl ether; amides such as N-methyl pyrrolidone;
ethers such as tetrahydorofuran, dioxane; ketones such as methyl
ethyl ketone, methyl isobutyl ketone; hydrocarbons such as liquid
paraffins, decane, decenes, methyl naphthalenes, decalin, kerosene,
diphenyl methane, toluene, dimethyl benzenes, ethyl benzenes,
diethyl benzenes, propyl benzenes, cyclohexane, partially
hydrogenated triphenyl; silicone oils such as polydimethyl
siloxanes, partially octyl-substituted polydimethyl siloxanes,
partially phenyl-substituted polydimethyl siloxanes, fluorosilicone
oils; halogenated hydrocarbons such as chlorobenzenes,
dichlorobenzenes, bromobenzenes, chlorodiphenyls, chlorodiphenyl
methanes; fluorides; and ester compounds such as ethyl benzoate,
octyl benzoate, dioctyl phthalate, trioctyl trimellitate, dibutyl
sebacate, ethyl(meth)acrylate, butyl(meth)acrylate,
dodecyl(meth)acrylate, etc. may be used.
[0062] In a coating composition according to embodiments of the
present invention, the amount of the above mentioned carbon fibrous
structures to be mixed with a resin composition is not particularly
limited, and may be determined properly in view of any requirement,
for example, a requirement for certain electrical characteristics
of a transparent conductive film. For instance, 1-25 parts by
weight of the carbon fibrous structures may be added to 100 parts
by weight of the resin composition. For any amount within the above
additive range, it is possible to prepare a composition in which
carbon fibrous structures are uniformly distributed.
[0063] Incidentally, the coating composition according to
embodiments of the present invention may include various known
additives, such as, coloring agents involving pigments or dyes,
various kinds of stabilizers, antioxidants, ultraviolet absorbers,
flame retardants, and solvents, unless it disturb the purpose of
embodiments of the present invention.
[0064] A coating composition for the transparent conductive film
according to embodiments of the present invention may be prepared
as a highly dispersed system since the carbon fibrous structures to
be used each have a sparse structure and, therefore, may have good
dispersibility. More preferably, it is desirable to prepare the
coating composition by using a media mill, especially, a media mill
equipped with beads having a mean diameter of 0.05-1.5 mm, in order
to disperse carbon fibrous structures throughout the composition.
Specifically, before dispersion treatment using such a media mill,
it may be advantageous to subject the mixture to a dispersion
treatment using a high-shear type distributor as will be explained
in detail below.
[0065] When the particle diameter of beads to be used for the media
mill is too small, there is a concern that carbon fibrous
structures may be broken into more minute pieces. Another concern
is that dispersion of carbon fibrous structures may not progress
sufficiently because kinetic energies of the beads become too
small. Further, handling of the beads also becomes difficult.
Therefore, it is desirable that the average diameter of the beads
is not less than 0.05 mm, preferably not less than 0.5 mm. On the
other hand, when the particle diameter of the beads to be used is
too large, inadequate milling applied to carbon fibrous structures
becomes the major concern because the number of beads per unit
volume is decreased with increasing diameter and, therefore,
lowering the dispersion efficiency. As a result, there is a
possibility that carbon fibrous structures in the composition may
have a large aspect ratio, and the liquidity for the paint or
coating agent cannot be expected. Therefore, it is desirable that
the average diameter of the beads is not more than 1.5 mm,
preferably not more than 1.0 mm.
[0066] The beads material as a dispersion media to be used for the
media mill is not specifically limited. For example, alumina,
zirconia, steel, chrome steel, glass, and etc., may be used. Among
them, zirconia beads are preferable, considering the possible
existence of impurities in the product and the magnitude of kinetic
energy, which is dependent on the specific gravity of the beads
material.
[0067] The shape of the beads is not specifically limited, but, in
general, globular or sphere beads are used.
[0068] The type of the media mill to be used is not specifically
limited, and any known media mill can be used. For example, various
known ATWRITERs, sand mills, ball mills, etc. can be used.
[0069] Incidentally, the filling rate of the beads in the vessel of
a mill may be determined in accordance with the configuration, etc.
of the vessel and stirrer, and is not specifically limited. If the
rate is too low, however, there is a concern that the mill may not
deliver adequate milling or cutting forces to carbon fibrous
structures. On the other hand, if it is too high, the concern is
that the high driving force for rotating the mill is needed.
Furthermore, because of the increase in the beads' abrasion, there
is a concern that contamination in the composition becomes worse.
Therefore, it is desirable that the filling rate of the beads is
set at 70-85% of the effective volume of the vessel.
[0070] Operating conditions such as processing time, axis rotation
number, internal pressure in the vessel, motor load, etc., may be
varied depending on the amount of carbon fibrous structures to be
mixed, the characteristics of the resin into which the carbon
fibrous structures are dispersed, particularly, viscosity and
compatibility of the resin with the carbon fibrous structure. Thus,
the specific conditions should be set appropriately according to
the purpose.
[0071] A preferable example of a high-shear type distributor to be
used before the dispersion treatment using a media mill is a mixer
that includes a stirring wheel capable of high speed rotation, and
a vessel whose inner peripheral surface is set to be closely
adjacent to the outer peripheral surface of the stirring wheel.
During operation, the wheel is rotated at a tip speed of not less
than 30 m/sec in order to force the liquid to be pressed as a thin
film against the inner peripheral surface of the vessel by the
centrifugal force. The thin film is allowed to contact the tips of
the wheel to perform stirring of the liquid. Other in-line rotor
and stator type mixers may also be used preferably. One example of
a desirable high-shear type distributor is the T.K. FILMICS.RTM.
manufactured by TOKUSHU KIKA KOGYO CO., LTD.
[0072] Alternatively, any of other high-shear type distributors,
such as T.K LABO DISPER, T.K. PIPELINE MIXER, T.K. HOMOMIC LINE
MILL.RTM., T.K. HOMO JETTOR, T.K. UNI-MIXER, T.K. HOMOMIC LINE
FLOW.RTM., T.K. AGI HOMO DISPER (manufactured by TOKUSHI KIKA KOGYO
Co., Ltd.), homogenizer POLYTRON.RTM. (manufactured by KINEMATICA
AG), homogenizer Physcotron (manufactured by Microtec Co., Ltd.),
BIOMIXER(manufactured by Nippon Seiki Co., Ltd.), turbo type
stirring machine (manufactured by KODAIRA SEISAKUSHO Co., Ltd.),
ULTRA DISPER (ASADA IRON WORKS. Co., Ltd.), EBARA MILDER
(manufactured by Ebara Corporation) may be used.
EXAMPLES
[0073] Hereinafter, this invention will be illustrated in detail by
practical examples. However, it is to be understood that the
examples are given for illustrative purposes only, and the
invention is not limited thereto.
[0074] The respective physical properties illustrated later in the
examples are measured by the following protocols.
Bulk Density
[0075] One gram (1 g) of powder was added into a transparent
circular cylinder which has 70 mm of an inner diameter equipped
with a distribution plate. Then, 1.3 liter of air at 0.1 Mpa of
pressure was supplied from the lower side of the distribution plate
in order to blow the powder loose. Afterwards, the powder was
allowed to settle naturally. After the fifth air blowing, the
height of the settled powder layer was measured. Six random data
points were taken and averaged in order to determine the bulk
density.
Raman Spectroscopic Analysis
[0076] Raman spectroscopic analysis was performed with LabRam 800
manufactured by HORIBA JOBIN YVON, S.A.S., using a 514 nm
wavelength argon laser.
TG Combustion Temperature
[0077] Combustion behavior was determined using TG-DTA manufactured
by MAX SCIENCE CO. LTD., at an air flow rate of 0.1 liter/minute
and a heating rate of 10.degree. C./minute. When combustion occurs,
TG indicates a quantity reduction and DTA indicates an exothermic
peak. Thus, the top position of the exothermic peak was defined as
the combustion initiation temperature.
X Ray Diffraction
[0078] Using a powder X ray diffraction equipment (JDX3532,
manufactured by JEOL Ltd.), the structures of carbon fibers after
annealing processing were analyzed. K.alpha. ray generated with a
Cu tube at 40 kV, 30 mA was used, and measurement of the spacing
was performed in accordance with the method defined by The Japan
Society for the Promotion of Science (JSPS), described in "Latest
Experimental Technique For Carbon Materials (Analysis Part),"
Edited by Carbon Society of Japan, 2001. Silicon powder was used as
an internal standard. The related parts of this literature are
incorporated herein by reference.
Particle's Resistance and Decompressibility
[0079] One gram (1 g) of CNT powder was weighed out, and then
press-loaded into a resinous die (inner dimensions: 40 L, 10 W, 80
Hmm). The displacement and load were read out. A constant current
was applied to the powder using the four-terminal method, and the
voltage was measured under this condition. After monitoring the
voltage until the density came to 0.9 g/cm.sup.3, the applied
pressure was released and the density after decompression was
measured. Measurements taken when the powder was compressed to 0.5,
0.8 or 0.9 g/cm.sup.3 were adopted as the particle's
resistance.
Coating Ability
[0080] This property was determined according to the following
criteria.
[0081] .smallcircle.: It is easy to coat by a bar coater.
[0082] .times.: It is difficult to coat by a bar coater.
Total Light Transmittance
[0083] Total light transmittance was determined in accordance with
JIS K 7361, by using a haze/transmittance meter HM-150
(manufactured by MURAKAMI COLOR RESEARCH LABORATORY), for a coating
film having a prescribed thickness formed on a glass plate (total
light transmittance of 91.0%, 50.times.50.times.2 mm).
Surface Resistivity
[0084] A 50.times.50 mm coated harden film was prepared on a glass
plate.
[0085] Using a 4-pin probe type resistivity meter (MCP-T600 or
MCP-HT4500, both manufactured by Mitsubishi Chemical), the
resistance (.OMEGA.) at nine points on the coated film surface was
measured. The measured values were converted into volume
resistivity (.OMEGA.cm) by the resistivity meter. An average was
then calculated.
Synthetic Example 1
[0086] Carbon fibrous structures were synthesized using toluene as
a raw material in a CVD process.
[0087] The synthesis was carried out in the presence of a mixture
of ferrocene and thiophene as a catalyst, and in the reducing
atmosphere of hydrogen gas. The toluene and the catalyst were
heated to 380.degree. C. along with the hydrogen gas. The heated
mixture was then supplied to a generation furnace and subjected to
thermal decomposition at 1250.degree. C. in order to obtain carbon
fibrous structures (the first intermediate). The synthesized first
intermediate was baked at 900.degree. C. in nitrogen gas in order
to remove hydrocarbons, such as tar, to produce a second
intermediate. The R value of the second intermediate, as measured
by Raman spectroscopic analysis, was found to be 0.98. A sample for
electron microscopy was prepared by dispersing the first
intermediate into toluene. FIG. 1 shows a TEM photo of the
sample.
[0088] The second intermediate was further subjected to a high
temperature heating treatment at 2600.degree. C. in argon. The
obtained aggregates of the carbon fibrous structures were
pulverized using an air flow pulverizer in order to produce carbon
fibrous structures according to the present invention. A sample for
electron microscopy was prepared by dispersing ultrasonically the
obtained carbon fibrous structures into toluene. FIGS. 2A and 2B
show TEM photos of the sample.
[0089] X-ray diffraction analysis and Raman spectroscopic analysis
were performed on the carbon fibrous structures before and after
the high temperature heating treatment in order to examine the
changes. The results are shown in FIGS. 3 and 4, respectively.
[0090] It was found that the carbon fibrous structures had a bulk
density of 0.0032 g/cm.sup.3, a Raman .sub.D/I.sub.G ratio of
0.090, a TG combustion temperature of 786.degree. C., a spacing of
3.383 angstrom, a particle's resistance of 0.0083 .OMEGA.cm, and a
density after decompression of 0.25 g/cm.sup.3.
Examples 1-9
[0091] The carbon fibrous structures obtained in Synthetic Example
1 was added to 100 parts by weight of polyurethane resin solution
(non-volatile matter: 20%) at ratios shown in Table 1. The
resultant mixture was pulverized and dispersed by using a bead mill
(DYNO-MILL, manufactured by SHINMARU ENTERPRISES CORPORATION) with
zirconium beads (0.05 mm, 0.5 mm, 1.0 mm, or 1.5 mm in diameter) at
a peripheral speed of 10 m/sec, a bead filling rate of 80% by
volume, and a processing time of 2 hrs. As a result, a coating
composition comprising the carbon fibrous structures dispersed
therein was prepared.
[0092] The liquid resinous composition obtained above was coated on
a glass plate to obtain a hardened film of a prescribed thickness
shown in Table 1. The hardened film was tested for coating ability,
total light transmittance, and surface resistivity. The results
obtained are shown in Table 1.
[0093] Furthermore, the dispersion condition of the carbon fibrous
structures in the hardened coating film was observed by an electron
microscope. The result obtained is shown in FIG. 5.
Reference Examples 1-6
[0094] To prepare the coating compositions of Reference Examples
1-6, the same procedure in Examples 1-9 was repeated except that
the dispersion method and its condition were changed as shown in
Table 1. Then, the same tests for coating ability, total light
transmittance, and surface resistivity as in Examples 1-9 were
performed. The results obtained are shown in Table 1.
Controls 1-4
[0095] Multilayered carbon nanotubes (manufactured by Tsinghua
Nafine, 10-20 nm in outer diameter, several .mu.m to several tens
.mu.m in length) were added to 100 parts by weight of a
polyurethane resin solution (non-volatile matter: 20%) at ratios
shown in Table 1. The resultant mixture was pulverized and
dispersed by using a bead mill (DYNO-MILL, manufactured by SHINMARU
ENTERPRISES CORPORATION) with zirconium beads (0.05 mm, or 1.5 mm
in diameter) at a peripheral speed of 10 m/sec, a bead filling rate
of 80% by volume, and a processing time of 2 hrs. As a result, a
coating composition comprising the carbon fibers dispersed therein
was prepared.
[0096] The liquid resinous composition thus obtained was coated on
a glass plate to obtain a hardened film of a prescribed thickness
shown in Table 1. The hardened film was tested for coating ability,
total light transmittance, and surface resistivity. The results
obtained are shown in Table 1.
Examples 10-18
[0097] The carbon fibrous structures obtained in Synthetic Example
1 was added to 100 parts by weight of a polyester resin solution
(non-volatile matter: 65%) at ratios shown in Table 2. The
resultant mixture was pulverized and dispersed by using a bead mill
(DYNO-MILL, manufactured by SHINMARU ENTERPRISES CORPORATION) with
zirconium beads (0.05 mm, 0.5 mm, 1.0 mm, or 1.5 mm in diameter) at
a peripheral speed of 10 m/sec, a beads filling rate of 80% by
volume, and a processing time of 2 hrs. As a result, a coating
composition comprising the carbon fibrous structures dispersed
therein was prepared.
[0098] The liquid resinous composition thus obtained was coated on
a glass plate to obtain a hardened film of a prescribed thickness
as shown in Table 2. The hardened film was tested for coating
ability, total light transmittance, and surface resistivity. The
results obtained are shown in Table 2.
Reference Examples 7-12
[0099] To prepare the coating compositions of Reference Examples
7-12, the same procedure in Examples 10-18 was repeated, except
that the dispersion method and its condition were changed as shown
in Table 2. The same tests for coating ability, total light
transmittance, and surface resistivity as in Examples 10-18 were
performed. The results obtained are shown in Table 2.
Controls 5-8
[0100] Multilayered carbon nanotubes (manufactured by Tsinghua
Nafine, 10-20 nm in outer diameter, several .mu.m to several tens
.mu.m in length) was added to 100 parts by weight of a polyester
resin solution (non-volatile matter: 65%) at ratios shown in Table
2. The resultant mixture was pulverized and dispersed by using a
bead mill (DYNO-MILL, manufactured by SHINMARU ENTERPRISES
CORPORATION) with zirconium beads (0.05 mm, or 1.5 mm in diameter)
at a peripheral speed of 10 m/sec, a bead filling rate of 80% by
volume, and a processing time of 2 hrs. As a result, a coating
composition comprising the carbon fibers dispersed therein was
prepared.
[0101] The liquid resinous composition thus obtained was coated on
a glass plate to obtain a hardened film of a prescribed thickness
as shown in Table 2. The hardened film was tested for coating
ability, total light transmittance, and surface resistivity. The
results obtained are shown in Table 2.
Examples 19-27
[0102] The carbon fibrous structures obtained in Synthetic Example
1 was added to 100 parts by weight of a phenolic resin
(non-volatile matter: 50%) at ratios shown in Table 3. The
resultant mixture was pulverized and dispersed by using a bead mill
(DYNO-MILL, manufactured by SHINMARU ENTERPRISES CORPORATION) with
zirconium beads (0.05 mm, 0.5 mm, 1.0 mm, or 1.5 mm in diameter) at
peripheral speed of 10 m/sec, a bead filling rate of 80% by volume,
and a processing time of 2 hrs. As a result, a coating composition
comprising the carbon fibrous structures dispersed therein was
prepared.
[0103] The liquid resinous composition thus obtained was coated on
a glass plate to obtain a hardened film of a prescribed thickness
as shown in Table 3. The hardened film was tested for coating
ability, total light transmittance, and surface resistivity. The
results obtained are shown in Table 3.
Reference Examples 13-18
[0104] To prepare the coating compositions of Reference Examples
13-18, the same procedure in Examples 19-27 was repeated, except
that the dispersion method and its condition were changed as shown
in Table 3. The same tests for coating ability, total light
transmittance, and surface resistivity as in Examples 19-27 were
performed. The results obtained are shown in Table 3.
Controls 9-12
[0105] Multilayered carbon nanotubes (manufactured by Tsinghua
Nafine, 10-20 nm in outer diameter, several .mu.m to several tens
.mu.m in length) was added to 100 parts by weight of phenolic resin
(non-volatile matter: 50%) at ratios shown in Table 3. The
resultant mixture was pulverized and dispersed by using a bead mill
(DYNO-MILL, manufactured by SHINMARU ENTERPRISES CORPORATION) with
zirconium beads (0.05 mm, or 1.5 mm in diameter) at a peripheral
speed of 10 m/sec, a bead filling rate of 80% by volume, and a
processing time of 2 hrs. As a result, a coating composition
comprising the carbon fibers dispersed therein was prepared.
[0106] The liquid resinous composition thus obtained was coated on
a glass plate to obtain a hardened film of a prescribed thickness
shown in Table 3. The hardened film was tested for coating ability,
total light transmittance, and surface resistivity. The results
obtained are shown in Table 3.
Examples 28-36
[0107] The carbon fibrous structures obtained in Synthetic Example
1 was added to 100 parts by weight of acrylic resin (non-volatile
matter: 35%) at ratios shown in Table 4. The resultant mixture was
pulverized and dispersed by using a bead mill (DYNO-MILL,
manufactured by SHINMARU ENTERPRISES CORPORATION) under the
conditions of zirconium beads (0.05 mm, 0.5 mm, 1.0 mm, or 1.5 mm
in diameter) at a peripheral speed of 10 m/sec, a beads filling
rate of 80% by volume, and a processing time of 2 hrs. As a result,
a coating composition comprising the carbon fibrous structures
dispersed therein was prepared.
[0108] The liquid resinous composition thus obtained was coated on
a glass plate to obtain a hardened film of a prescribed thickness
shown in Table 4. The hardened film was tested for coating ability,
total light transmittance, and surface resistivity. The results
obtained are shown in Table 4.
Reference Examples 19-24
[0109] To prepare the coating compositions of Reference Examples
19-24, the same procedure in Examples 28-36 was repeated, except
that the dispersion method and its condition were changed as shown
in Table 4. Then, the same tests for coating ability, total light
transmittance, and surface resistivity as in Examples 28-36 were
performed.
[0110] The results obtained are shown in Table 4.
Controls 13-16
[0111] Multilayered carbon nanotubes (manufactured by Tsinghua
Nafine, 10-20 nm in outer diameter, several .mu.m to several tens
.mu.m in length) was added to 100 parts by weight of a acrylic
resin (non-volatile matter: 35%) at ratios shown in Table 4. The
resultant mixture was pulverized and dispersed by using a bead mill
(DYNO-MILL, manufactured by SHINMARU ENTERPRISES CORPORATION) with
zirconium beads (0.05 mm, or 1.5 mm in diameter) at a peripheral
speed of 10 m/sec, a bead filling rate of 80% by volume, and a
processing time of 2 hrs. As a result, a coating composition
comprising the carbon fibers dispersed therein was prepared.
[0112] T the liquid resinous composition thus obtained was coated
on a glass plate to obtain a hardened film of a prescribed
thickness shown in Table 4. The hardened film was tested for
coating ability, total light transmittance, and surface
resistivity. The results obtained are shown in Table 4.
Examples 37-40
[0113] The same procedures in Examples 6, 15, 24, and 33 were
repeated except that an additional dispersion treatment, using T.K.
FILMICS.RTM. (manufactured by TOKUSHI KIKA KOGYO CO., LTD) at a tip
speed of 50 m/sec for 2 minutes, was performed before the
dispersion treatment using the bead mill. As a result, a coating
composition comprising the carbon fibrous structures dispersed
therein was prepared.
[0114] The liquid resinous composition thus obtained was coated on
a glass plate to obtain a hardened film of a prescribed thickness
shown in Tables 1-4. The hardened film was tested for coating
ability, total light transmittance, and surface resistivity. The
results obtained are shown in Tables 1-4. TABLE-US-00001 TABLE 1
Example 1 2 3 4 5 6 7 8 9 37 Polyurethane resin 100 100 100 100 100
100 100 100 100 100 Carbon fibrous 5 1.5 2 2 5 5 25 25 25 5
structures Multilayered CNT Method Bead mill .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. dispersion Ball mill dispersion Homogenizer
dispersion Pretreatment .smallcircle. (high-shear type dispersion)
Beads' diameter 1.0 0.05 0.05 1.5 0.5 1.0 0.5 1.0 1.5 1.0 (mm)
Thickness(.mu.m) 0.2 1.0 1.0 3.0 0.5 1.5 1.0 1.0 4.5 1.5 Coating
ability .smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. Total light 88.5 90.2 87.5 77.3 83.5
70.5 52.5 52.8 33.8 78.4 transmittance Surface resistivity 3.8
.times. 10.sup.8 2.7 .times. 10.sup.11 3.6 .times. 10.sup.10 2.4
.times. 10.sup.9 5.8 .times. 10.sup.7 4.7 .times. 10.sup.6 1.2
.times. 10.sup.2 3.7 .times. 10.sup.2 2.6 .times. 10.sup.1 1.1
.times. 10.sup.6 Reference Control 1 2 3 4 5 6 1 2 3 4 Polyurethane
resin 100 100 100 100 100 100 100 100 100 100 Carbon fibrous 1.5
0.5 35 5 5 5 structures Multilayered CNT 1.5 1.5 5 5 Method Bead
mill .smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. dispersion
Ball mill dispersion .smallcircle. Homogenizer .smallcircle.
dispersion Pretreatment (high-shear type dispersion) Beads'
diameter 0.03 0.05 0.05 2.0 0.5 0.5 0.05 1.5 0.05 1.5 (mm)
Thickness(.mu.m) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Coating
ability .smallcircle. .smallcircle. X .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. Total light 89.4 90.5 ND ND ND ND 22.3 17.5 ND ND
transmittance Surface resistivity >10.sup.12 >10.sup.12 2.9
.times. 10.sup.1 2.1 .times. 10.sup.6 9.8 .times. 10.sup.5 3.7
.times. 10.sup.6 >10.sup.12 >10.sup.12 3.5 .times. 10.sup.9
1.3 .times. 10.sup.9 ND: not determined multilayered CNT:
multilayered carbon nanotube (manufactured by Tsinghua Nafine,
10-20 nm in outer diameter, several .mu.m to several tens .mu.m in
length)
[0115] TABLE-US-00002 TABLE 2 Example 10 11 12 13 14 15 16 17 18 38
Polyester resin 100 100 100 100 100 100 100 100 100 100 Carbon
fibrous 5 1.5 2 2 5 5 25 25 25 5 structures Multilayered CNT Method
Bead mill .largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. dispersion Ball mill dispersion
Homogenizer dispersion Pretreatment .largecircle. (high-shear type
dispersion) Beads' diameter 1.0 0.05 0.05 1.5 0.5 1.0 0.5 1.0 1.5
1.0 (mm) Thickness(.mu.m) 0.2 1.0 1.0 3.0 0.5 1.5 1.0 1.0 4.5 1.5
Coating ability .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Total light 83.8 89.2
84.5 73.8 83.8 69.8 52.4 51.7 33.2 74.8 transmittance Surface
resistivity 6.8 .times. 10.sup.8 4.2 .times. 10.sup.11 5.1 .times.
10.sup.10 3.4 .times. 10.sup.9 2.8 .times. 10.sup.7 4.3 .times.
10.sup.6 3.2 .times. 10.sup.2 5.3 .times. 10.sup.2 4.5 .times.
10.sup.1 2.7 .times. 10.sup.6 Reference Control 7 8 9 10 11 12 5 6
7 8 Polyester resin 100 100 100 100 100 100 100 100 100 100 Carbon
fibrous 1.5 0.5 35 5 5 5 structures Multilayered CNT 1.5 1.5 5 5
Method Bead mill .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. dispersion Ball mill dispersion .largecircle.
Homogenizer .largecircle. dispersion Pretreatment (high-shear type
dispersion) Beads' diameter 0.03 0.05 0.05 2.0 0.5 0.5 0.05 1.5
0.05 1.5 (mm) Thickness(.mu.m) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
1.0 Coating ability .largecircle. .largecircle. X .largecircle.
.largecircle. X .largecircle. .largecircle. .largecircle.
.largecircle. Total light 87.5 90.2 ND ND ND ND 24.5 20.1 ND ND
transmittance Surface resistivity >10.sup.12 >10.sup.12 5.3
.times. 10.sup.1 3.2 .times. 10.sup.6 8.6 .times. 10.sup.5 4.3
.times. 10.sup.6 >10.sup.12 >10.sup.12 4.4 .times. 10.sup.9
2.8 .times. 10.sup.9 ND: not determined multilayered CNT:
multilayered carbon nanotube (manufactured by Tsinghua Nafine,
10-20 nm in Outer diameter, several .mu.m to several tens .mu.m in
length)
[0116] TABLE-US-00003 TABLE 3 Example 19 20 21 22 23 24 25 26 27 39
Phenolic resin 100 100 100 100 100 100 100 100 100 100 Carbon
fibrous 5 1.5 2 2 5 5 25 25 25 5 structures Multilayered CNT Method
Bead mill .largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. dispersion Ball mill dispersion
Homogenizer dispersion Pretreatment .largecircle. (high-shear type
dispersion) Beads' diameter 1.0 0.05 0.05 1.5 0.5 1.0 0.5 1.0 1.5
1.0 (mm) Thickness(.mu.m) 0.2 1.0 1.0 3.0 0.5 1.5 1.0 1.0 4.5 1.5
Coating ability .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Total light 82.1 89.5
81.2 74.8 82.4 65.2 51.9 50.3 33.6 72.5 transmittance Surface
resistivity 4.9 .times. 10.sup.8 4.2 .times. 10.sup.11 5.7 .times.
10.sup.10 4.1 .times. 10.sup.9 7.3 .times. 10.sup.7 5.2 .times.
10.sup.6 3.2 .times. 10.sup.2 5.2 .times. 10.sup.2 8.6 .times.
10.sup.1 1.6 .times. 10.sup.6 Reference Control 13 14 15 16 17 18 9
10 11 12 Phenolic resin 100 100 100 100 100 100 100 100 100 100
Carbon fibrous 1.5 0.5 35 5 5 5 structures Multilayered CNT 1.5 1.5
5 5 Method Bead mill .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. dispersion Ball mill dispersion .largecircle.
Homogenizer .largecircle. dispersion Pretreatment (high-shear type
dispersion) Beads' diameter 0.03 0.05 0.05 2.0 0.5 0.5 0.05 1.5
0.05 1.5 (mm) Thickness(.mu.m) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
1.0 Coating ability .largecircle. .largecircle. X .largecircle.
.largecircle. X .largecircle. .largecircle. .largecircle.
.largecircle. Total light 88.7 89.6 ND ND ND ND 18.6 13.8 ND ND
transmittance Surface resistivity >10.sup.12 >10.sup.12 4.2
.times. 10.sup.1 3.4 .times. 10.sup.6 1.6 .times. 10.sup.6 5.3
.times. 10.sup.6 >10.sup.12 >10.sup.12 3.9 .times. 10.sup.9
2.3 .times. 10.sup.9 ND: not determined multilayered CNT:
multilayered carbon nanotube (manufactured by Tsinghua Nafine,
10-20 nm in outer diameter, several .mu.m to several tens .mu.m in
length)
[0117] TABLE-US-00004 TABLE 4 Example 28 29 30 31 32 33 34 35 36 40
Acrylic resin 100 100 100 100 100 100 100 100 100 100 Carbon
fibrous 5 1.5 2 2 5 5 25 25 25 5 structures Multilayered CNT Method
Bead mill .largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. dispersion Ball mill dispersion
Homogenizer dispersion Pretreatment .largecircle. (high-shear type
dispersion) Beads' diameter 1.0 0.05 0.05 1.5 0.5 1.0 0.5 1.0 1.5
1.0 (mm) Thickness(.mu.m) 0.2 1.0 1.0 3.0 0.5 1.5 1.0 1.0 4.5 1.5
Coating ability .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Total light 87.2 88.5
84.8 76.2 85.1 66.4 54.3 53.7 34.6 76.5 transmittance Surface
resistivity 5.2 .times. 10.sup.8 1.4 .times. 10.sup.11 1.9 .times.
10.sup.11 2.1 .times. 10.sup.9 3.5 .times. 10.sup.7 2.5 .times.
10.sup.6 1.8 .times. 10.sup.2 4.5 .times. 10.sup.2 4.8 .times.
10.sup.1 1.2 .times. 10.sup.6 Reference Control 19 20 21 22 23 24
13 14 15 16 Acrylic resin 100 100 100 100 100 100 100 100 100 100
Carbon fibrous 1.5 0.5 35 5 5 5 structures Multilayered CNT 1.5 1.5
5 5 Method Bead mill .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. dispersion Ball mill dispersion .largecircle.
Homogenizer .largecircle. dispersion Pretreatment (high-shear type
dispersion) Beads' diameter 0.03 0.05 0.05 2.0 0.5 0.5 0.05 1.5
0.05 1.5 (mm) Thickness(.mu.m) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
1.0 Coating ability .largecircle. .largecircle. X .largecircle.
.largecircle. X .largecircle. .largecircle. .largecircle.
.largecircle. Total light 90.2 89.5 ND ND ND ND 32.1 28.7 ND ND
transmittance Surface resistivity >10.sup.12 >10.sup.12 5.1
.times. 10.sup.1 3.6 .times. 10.sup.6 5.3 .times. 10.sup.5 2.4
.times. 10.sup.6 >10.sup.12 >10.sup.12 5.5 .times. 10.sup.9
3.3 .times. 10.sup.9 ND: not determined multilayered CNT:
multilayered carbon nanotube (manufactured by Tsinghua Nafine,
10-20 nm in outer diameter, several .mu.m to several tens .mu.m in
length)
[0118] The present invention may be embodied in other specific
forms without departing from the scope or essential characteristics
thereof. The present embodiments and examples are therefore to be
considered in all respects as illustrative and not restrictive, the
scope of the invention being indicated by the appended claims
rather than by the foregoing description and all changes which come
within the meaning and range of equivalency of the claims are
therefore intended to be embraced therein.
* * * * *