A transparent
conductive film has a cured layer mainly containing a curable resin and
a transparent conductive thin film successively layered on a
transparent plastic film base. The transparent conductive film is
characterized in that it has 3-200 protrusions over the surface of the
transparent conductive thin film per 100 µm2, each having a
diameter of 0.05-3.0 µm and a height of 0.005-2.00 µm. The transparent
conductive film is characterized in that a volatile component amount
contained in the transparent conductive film is at most 30 Pa.
BACKGROUND OF THE
INVENTION
1. Field of the Invention
The present invention relates to a transparent conductive film or
transparent conductive sheet with a cured layer and transparent conductive
thin film successively layered on a transparent plastic film base as well
as a touchpanel using the same. More particularly, the present invention
relates to a transparent conductive film or transparent conductive sheet
with excellent resistance to pen sliding when used for a touchpanel for
pen input as well as a touchpanel using the same.
2. Description of the Background Art
Transparent conductive films with a transparent thin film having small
resistance layered on a transparent plastic film base are widely used in
electrical and electronic fields, e.g., in a
flat panel display such as a
liquid crystal display or an electroluminescence (EL) display and a
transparent electrode for a touchpanel.
Recently, due to a proliferation of portable information terminals,
notebook computers with touchpanels and the like, the demand for a
touchpanel with excellent resistance to pen sliding has been on the
increase.
When input is made to a touchpanel by a pen, transparent conductive thin
films on the sides of a fixed electrode and a movable electrode (film
electrode) are brought into contact. Therefore, a transparent conductive
film with excellent resistance to pen sliding is required which has
sufficient resistance to a load applied by the pen to prevent cracks,
separation and the like.
However, a conventional transparent conductive film suffers from the
following problem.
A transparent conductive film (Japanese Patent Laying-Open No. 2-66809) has
been proposed having a transparent conductive thin film on a transparent
plastic film base with a thickness of 120 µm or smaller applied to
another transparent base by a tackifier layer. However, after a 100,000
linear-sliding test with a load of 5.0N using a polyacetal pen, which will
later be described in conjunction with a sliding-resistance test, it was
found that separation was caused to the transparent conductive thin films
and resistance to pen input was unsatisfactory. Due to whitening of the
separated portion, a display quality decreases when used for a display
with a touchpanel.
A transparent conductive film with a layer formed by hydrolysis of an
organosilicon compound on a transparent plastic film base and further
having a crystalline transparent conductive thin film layered thereon has
been proposed for example in Japanese Patent Laying-Open No. 60-131711,
No. 61-79647, No. 61-183809, No. 2-194943, No. 2-276630, and No. 8-64034.
However, such a transparent conductive film is extremely fragile because of
its crystallinity and small thickness. Thus, after a 100,000
linear-sliding test with a load of 5.0N using a polyacetal pen which will
later be described in conjunction with a sliding-resistance test, cracks
are caused to the transparent conductive thin film. In addition, since a
thermal treatment at about 150° C. is required after sputtering the
transparent conductive thin film, such a film involves high process cost.
Further, a conductive plastic layer stack with a transparent conductive
thin film formed on a curable coating layer has been proposed in Japanese
Patent Laying-Open No. 2-5308 and No. 2000-62074. However, although the
layer stack is sufficient for use as a transparent electrode of a liquid
crystal display, it does not have sufficient sliding-resistance when used
for a touchpanel. This is because a residual volatile component is
gasified from the cured coating layer during fabrication of the
transparent conductive thin film, whereby the quality of the transparent
conductive thin film decreases.
SUMMARY OF THE INVENTION
In view of the above, an object of the present invention is to provide a
transparent conductive film or a transparent conductive sheet which
exhibits excellent resistance to pen input when used for a touchpanel and,
in particular, which prevents breakage of a the transparent conductive
thin film even after a 100,000 sliding test with a load of 5.0N using a
polyacetal pen which will later be described in conjunction with a
sliding-resistance test, as well as a touchpanel using the same. The
transparent conductive film, transparent conductive sheet and touchpanel
of the present invention which solve the aforementioned problem are set
forth in the following.
Namely, the present invention is a transparent conductive film having a
cured layer mainly containing a curable resin and a transparent conductive
thin film successively layered on a transparent plastic film base, which
is characterized in that 3-200 protrusions, each having a diameter of
0.05-3.0 µm and a height of 0.005-2.00 µm, are formed per 100
µm
2 over a surface of the transparent conductive thin film.
According to another aspect of the present invention, the transparent
conductive film is characterized in that the curable resin is an
ultraviolet-curable resin, a resin which is insoluble with the
ultraviolet-curable resin is a polyester resin having an average molecular
weight of 5,000-50,000, and the polyester resin is contained in an amount
of 0.10-20 parts by weight with respect to 100 parts of the
ultraviolet-curable resin.
According to another aspect of the present invention, the transparent
conductive film is characterized in that the transparent conductive thin
film is formed of an indium-tin oxide compound or a tin-antimony oxide
compound.
According to another aspect of the present invention, the transparent
conductive film is characterized in that a hardcoat layer is formed on the
transparent conductive film on the side opposite the transparent
conductive thin film.
According to another aspect of the present invention, the transparent
conductive film is characterized in that the hardcoat layer has an
anti-glare effect.
According to another aspect of the present invention, the transparent
conductive film is characterized in that the hardcoat layer is subjected
to a treatment for low reflection.
According to another aspect of the present invention, the transparent
conductive sheet is characterized in that a transparent resin sheet is
applied to the transparent conductive film by a tackifier on the side
opposite the transparent conductive thin film.
According to another aspect of the present invention, in a touchpanel
having a pair of panel plates with the transparent conductive thin films
arranged through a spacer such that the transparent conductive films are
opposite each other, the touchpanel is characterized in that at least one
panel plate is formed of the above mentioned transparent conductive film
or transparent conductive sheet.
The foregoing and other objects, features, aspects and advantages of the
present invention will become more apparent from the following detailed
description of the present invention when taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 to 8 are diagrams respectively showing output shapes from a
touchpanel according to first to eighth examples of the present invention.
FIGS. 9 to 12 are diagrams respectively showing output shapes from a
touchpanel according to first to fourth comparative examples.
FIG. 13 is a cross sectional view of a touchpanel obtained with use of a
transparent conductive film of the present invention.
FIG. 14 is a cross sectional view of a touchpanel formed of plastic which
does not employ a glass plate obtained by using a transparent conductive
film and a transparent conductive sheet of the present invention.
FIG. 15 is a picture taken by a scanning-type electronic microscope showing
a transparent conductive thin film surface in a transparent conductive
film of the fourth example.
FIGS. 16 to 25 are diagrams respectively showing output shapes from a
touchpanel according to ninth to eighteenth examples of the present
invention.
FIG. 26 is a graph showing a relationship between hardness and indentation
fracture depth used for hardness measurement of the transparent conductive
thin film of the fourteenth example of the present invention.
DESCRIPTION OF THE PREFERRED EXAMPLES
A transparent plastic film base used in the present invention refers to a
film obtained by melt-extruding or solution-extruding an organic polymer
and performing drawing, cooling and thermosetting in a longitudinal
direction and/or a width direction as necessary. Examples of organic
polymer include polyethylene, polypropylene, polyethylene terephthalate,
polyethylene-2, 6-naphthalate, polypropylene terephthalate, nylon 6, nylon
4, nylon 66, nylon 12, polyimide, polyamide-imide, polyether sulfin,
polyether ether ketone, polycarbonate, polyarylate, cellulose propionate,
polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyether
imide, polyphenylene sulfide, polyphenylene oxide, polystyrene,
syndiotactic polystyrene, and norbornene polymer.
Most preferably, among these organic polymers, polyethylene terephthalate,
polypropylene terephthalate, polyethylene-2, 6-naphthalate, syndiotactic
polystyrene, norbornene polymer, polycarbonate, polyarylate or the like is
used. Any of these organic polymers may be a copolymer obtained by
copolymerization with a small amount of another monomer, or a blend with
another organic polymer.
A thickness of a transparent plastic film base of the present invention is
preferably more than 10 µm and not more than 300 µm and, in
particular, a thickness of 70-260 µm is preferable. If the thickness of
the plastic film is 10 µm or smaller, a mechanical strength is
insufficient. In this case, particularly, deformation caused by pen input
when used for a touchpanel is too large to provide sufficient durability.
On the contrary, if the thickness exceeds 300 µm, a pen load for
deforming a film is too great when used for the touchpanel, which is not
preferable.
The transparent plastic film base used for the present invention may be
subjected to a surface activation treatment such as corona
discharge, glow
discharge, flame treatment, ultraviolet treatment, electronic treatment,
or ozonation treatment insofar as it does not adversely affect the object
of the present invention.
Although the curable resin used in the present invention is not
particularly limited insofar as it is curable by application of energy for
example from heating, ultraviolet ray irradiation, electronic irradiation
and the like, a resin which is curable by ultraviolet rays is preferable
in terms of productivity. Examples of such ultraviolet-curable resin
include a polyfunctional acrylate resin such as acrylic acid or
methacrylic acid ester of polyvalent alcohol, diisocyanate, polyvalent
alcohol, and polyfunctional urethane acrylate resin synthesized by
hydroxyalkyl ester of acrylic acid or methacrylic acid. Any of these
polyfunctional resins may be copolymerized with monofunctional monomer,
e.g., vinyl pyrrolidone, methyl methacrylate, styrene or the like.
The ultraviolet-curable resin is generally used with a photo polymerization
initiator added thereto. For the photo polymerization initiator, a known
compound which absorbs ultraviolet rays to generate radicals can be used
without any particular limitation. Examples of photo polymerization
initiator include various benzoins, phenyl ketones, and benzophenones. The
photo polymerization initiator is generally added in an amount of 1.0-5.0
parts by weight with respect to 100 parts of ultraviolet-curable resin.
The cured layer used in the present invention preferably contains a resin
insoluble with the curable resin in combination with the curable resin of
a main component. Addition of a small amount of resin insoluble with the
curable resin of a matrix causes phase separation in the curable resin and
dispersion of the resin insoluble with the curable resin as particles. The
dispersed particles of the insoluble resin can provide irregularities over
the cured surface.
If the curable resin is an ultraviolet-curable resin, a polyester resin,
polyolefin resin, polystyrene resin, and polyamide resin can be enumerated
as the insoluble resin.
The polyester resin preferably has a high average molecular weight of
5,000-50,000, and more particularly 8,000-30,000. If the average molecular
weight of the polyester resin is smaller than 5,000, it becomes difficult
to disperse the polyester resin in the cured layer with an appropriate
particle size. On the other hand, if the average molecular weight of the
polyester resin exceeds 50,000, solubility with respect to a solvent
decreases in preparing a coating liquid, which is not preferable.
The above mentioned polyester resin of high molecular weight is an
amorphous saturation polyester resin obtained by copolymerizing dihydric
alcohol and dihydric carboxylic acid, which is soluble in the solvent
common to the above mentioned ultraviolet-curable resin.
Examples of the above dihydric alcohol include ethylene glycol, propylene
glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol,
neopentyl glycol, 1,4-cyclohexanedimethanol, and hydrogenation bisphenol
A.
Examples of the above dihydric carboxylic acid include isophthalic acid,
terephthalic acid, adipic acid, phthalic anhydride, tetrahydro
anhydrous
phthalic acid, and hexahedron anhydrous phthalic acid.
Insofar as insufficiency of insolubility with respect to the solvent is not
caused, alcohol of at least trivalence such as trimethylol propane and
pentaerythritol, and carboxylic acid having at least trivalence such as
anhydride trimellitic acid or anhydrous pyromellitic acid can be
copolymerized.
In the present invention, as for the blending amount of the
ultraviolet-curable resin and polyester resin of high molecule amount
which are main components of the cured layer, the polyester resin is
preferably contained in an amount of 0.10-20 parts by weight with respect
to 100 parts of the ultraviolet-curable resin, and more preferably
contained in an amount of 0.20-10 parts by weight and particularly
preferably 0.50-5.0 parts by weight. If the blending amount of the
polyester resin is smaller than 0.10 parts by weight with respect to 100
parts of the ultraviolet-curable resin, the number of protrusions formed
over the surface of the cured layer becomes too small, which is not
preferable. On the other hand, because of the difference in refractive
index of the polyester resin and the ultraviolet-curable resin, if the
blending amount of the polyester resin exceeds 20 parts by weight with
respect to 100 parts of the ultraviolet-curable resin, the haze value of
the cured layer tends to be higher and transparency may be deteriorated,
which is not preferable. Conversely, by positively utilizing deterioration
of transparency due to dispersed particles in the polyester resin of high
molecular weight, a film with a high haze value can be used as an
anti-glare film.
The above mentioned ultraviolet-curable resin, photo polymerization
initiator, and polyester resin of high molecular weight are dissolved in
the same solvent to prepare a coating liquid. Although not particularly
limited, the solvent employed may be any of alcohols including ethyl
alcohol and isopropyl alcohol, acetic ether, esters including butyl
acetate, ethers including dibutyl ether, ethylene glycol monoethyl ether,
ketones including methyl isobutyl ketone and cyclohexanone, and aromatic
hydrocarbons including toluene, xylene and solvent naphtha, which may be
used independently or in combination. The concentration of the resin in
the coating liquid may be appropriately selected in consideration of
viscosity according to a coating method or the like. For example, the
total amount of the ultraviolet-curable resin, photo polymerization
initiator and polyester resin of high molecular weight is 20-80% by weight
of the coating liquid. In addition, other known additives, e.g., silicone
leveling agent or the like may be added to the coating liquid as
necessary.
In the present invention, the prepared coating liquid is applied to the
transparent plastic film base. Although not particularly limited, examples
of coating method include barcode method, gravure coating method, reverse
coating method or the like, which is conventionally known. The applied
coating liquid evaporates in the following drying step and is removed. In
this step, the polyester resin of high molecular weight evenly dissolved
in the coating liquid turns to fine particles to precipitate in the
ultraviolet-curable resin. After the coating is dried, ultraviolet rays
are further directed to the plastic film, and the ultraviolet-curable
resin is crosslinked and cured to form a cured layer. In this curing step,
the fine particles of the polyester resin of high molecular weight are set
in a hardcoat layer to form protrusions over the surface of the cured
layer.
The thickness of the cured layer is preferably 0.10-15 µm, more
preferably 0.50-10 µm, and particularly preferably 1.0-8.0 µm. If
the thickness of the cured layer is less than 0.10 µm, protrusions
which will later be described may be unsatisfactory. On the other hand,
the thickness exceeding 15 µm is not preferable in terms of
productivity.
Although not particularly limited insofar as it is a material having both
transparency and conductivity, as a transparent conductive thin film of
the present invention, an indium oxide, tin oxide, zinc oxide, indium-tin
oxide compound, tin-antimony oxide compound, zinc-aluminum oxide compound,
indium-zinc oxide compound, silver and silver alloy, copper and copper
alloy, gold and the like can be enumerated, which is in the form of a
single layer or a stack of at least two layers. Among these, an indium-tin
oxide compound or tin-antimony oxide compound is well suited in terms of
environmental stability or circuit workability.
The thickness of the transparent conductive thin film is preferably 4-800
nm, and particularly preferably 5-500 nm. If the thickness of the
transparent conductive thin film is smaller than 4 nm, formation of
continuous thin film and provision of good conductivity become difficult.
A thickness greater than 800 nm tends to lower transparency.
Examples of a method of forming the transparent conductive thin film of the
present invention include vacuum deposition, sputtering, CVD, ion
plating,
and spraying, although the method can be appropriately used according to a
required thickness.
For example, in the case of sputtering, a general sputtering method using
an oxide target, or a reactive sputtering using a metal target and the
like may be used. In this case, as a reactive gas, oxygen, nitrogen,
moisture vapor and the like may be introduced, or ozone addition, plasma
irradiation, ion assisting and the like may be used in combination.
Further, insofar as the object of the present invention is not adversely
affected, a bias such as direct current, alternating current, and high
frequency may be applied to a substrate.
A temperature in forming the transparent conductive thin film on the
transparent plastic film through the cured layer is preferably not higher
than 150° C. The temperature exceeding 150° C. during film
formation requires extremely low feeding speed of the plastic film, which
is unsuitable in terms of industrial application.
A vacuum for sputtering is preferably 0.01-13.0 Pa. If the vacuum exceeds
0.01 Pa, stable discharge and hence stable sputtering cannot be performed.
If the vacuum is below 13.0 Pa, similarly, stable discharge and hence
stable sputtering are not performed. This also applies to other methods
such as deposition and CVD.
To provide greater adhesion of the transparent conductive thin film and the
cured layer, it is effective to finish the cured layer. Specifically, a
discharge method irradiating glow or corona discharge to increase carbonyl
group, carboxyl group and hydrogen group, or a chemicalization process
treating with acid or alkali to increase polar group such as
amino group,
hydrogen group and carbonyl group can be enumerated.
Since the transparent conductive film of the present invention has a
transparent conductive layer formed on the cured layer having
irregularities obtained by utilizing phase separation, surface
irregularities of the cured layer also appear in the transparent
conductive layer. Specifically, 3-200 protrusions, each having a diameter
of 0.05-3.0 µm and a height of 0.01-2.0 µm, are formed over the
surface of the transparent conductive thin film per 100 µm
2.
The diameter of the protrusion must be 0.05-3.0 µm, preferably 0.06-2.0
µm, and particularly preferably 0.10-1.0 µm. The height of the
protrusion must be 0.005-2.00 µm, preferably 0.050-1.00 µm, and
particularly preferably 0.100-0.800 µm. Further, the number of
protrusions per 100 µm
2 over the surface of the transparent
conductive thin film must be 3-200, preferably 10-100, and particularly
preferably 20-80.
If the transparent conductive film of the present invention having the
above mentioned protrusions are used for a touchpanel, excellent
slidability is obtained with respect to the transparent conductive thin
film of the fixed electrode. Thus, even after a 100,000 linear-sliding
test with a load of 5.0N using a polyacetal pen (leading edge: 0.8 mmR),
the transparent conductive thin film is not deteriorated.
If the diameter of the protrusion is smaller than 0.05 µm, if the height
of the protrusion is smaller than 0.005 µm, or if the number of the
protrusions is less than 3 per 100 µm
2, good sidability is not
obtained. In this case, after the 100,000 linear-sliding test with a load
of 5.0N using a polyacetal pen (leading edge: 0.8 mmR), deterioration of
the transparent conductive thin film is observed and hence such size of
the protrusion is not preferable. On the other hand, if the diameter
exceeds 3 µm, if the height of the protrusion exceeds 2 µm, or if
the number of protrusions exceeds 200 per 100 µml, an increasing effect
of slidability comes to a saturation and a haze value increases. Thus,
such size of the protrusion is not preferable.
The transparent conductive thin film is formed on the cured layer by a
vacuum process such as sputtering, as described above. If a volatile
component is contained in the cured layer and/or plastic film, such vacuum
process is adversely affected.
If an indium-tin oxide compound thin film is formed by sputtering, for
example, sputtered indium atoms and gas vaporized from the cured layer
collide in a gas phase, whereby the energy of indium atoms decreases. As a
result, the hardness and quality of the transparent conductive thin film
formed on the cured layer are deteriorated.
The gas component volatilized from the cured layer is incorporated as
impurities. In this case also, a transparent conductive thin film with
inferior quality and hardness is formed. If a transparent conductive film
with such a transparent conductive thin film with inferior quality layered
thereon is used for a touchpanel, the transparent conductive thin film
exhibits degradation due to wearing after 100,000 linear-sliding test with
a load of 5.0N, which is not preferable.
Examples of volatile components in the cured layer include the above
mentioned solvent used for coating of the cured layer, a residual photo
polymerization initiator which did not contribute to ultraviolet curing
reaction, and a by-product thereof.
To reduce the amount of the volatile component, it is suitable to perform a
heat treatment after crosslinking reaction by ultraviolet irradiation. The
temperature at the time is preferably 100-200° C. If the
temperature is below 100° C., the volatile component is not
effectively reduced. If the temperature exceeds 200° C., the
planarity of the film is not readily maintained, which is not preferable.
Alternatively, the volatile component can be effectively reduced by
exposing the film to a vacuum in a vacuum chamber for sputtering or the
like. At the time, the volatile component can be more effectively reduced
by increasing the temperature of a roll which is in contact, or by heating
the film with an
infrared heater.
In these film-forming processes, immediately before forming a film,
preferably, a plastic film with a cured layer is maintained in a vacuum.
The vacuum exposure enables further reduction in volatile component
amount.
Having been subjected to such a process of reducing volatile component, the
transparent conductive film has a volatile component amount of at most 30
ppm. As such, the transparent conductive film has a transparent conductive
thin film of excellent quality. If the transparent conductive film is used
for a touchpanel, degradation of the transparent conductive thin film was
not seen after 100,000 linear-sliding test with a load of 5.0N with use of
a polyacetal pen (leading edge: 0.8 mmR).
Further, in the present invention, since the transparent conductive thin
film is provided with increased hardness, degradation of the transparent
conductive thin film due to a friction with respect to a glass plate is
not seen as a result of a pen sliding-resistance test when used for a
touchpanel.
The metal oxide forming the transparent conductive thin film is classified
as either amorphous or crystalline according to its electron diffraction
image. A crystalline metal oxide is produced by heating an amorphous metal
oxide. The crystalline metal oxide generally has greater hardness than the
amorphous metal oxide. However, as crystallization of the metal oxide
forming the conductive thin film proceeds, the conductive thin film
becomes more fragile. Thus, cracks tend to be caused to the thin film
after the linear-sliding test using a polyacetal pen.
To give greater hardness to the amorphous transparent conductive thin film,
the following two measures are effective in forming the transparent
conductive thin film.
(1) To increase the temperature of the film substrate.
(2) To eliminate impurities such as moisture in an ambient for film
formation.
To give greater hardness to the transparent conducive thin film, it is
important to increase the temperature of the film, which is to be a
substrate. This is because migration can occur over the substrate (film)
surface as evaporated particles are deposited when the transparent
conductive thin film is formed, so that more stable movement in terms of
energy is enabled, and the transparent conductive thin film with extremely
high density can be obtained. Since the evaporated particles of the metal
oxide can be deposited on the film substrate with high density, extremely
high hardness can be provided.
For example, when forming the transparent conductive thin film on the film
using a take-up apparatus by sputtering, the temperature of the film to be
a substrate can be increased by increasing the temperature of the roll in
contact with the back surface (the opposite side of the surface on which
the transparent conductive thin film is formed) of the film.
The temperature in forming the transparent conductive thin film on the
transparent plastic film to be a substrate is preferably 40-150° C.
If the temperature at the time of film formation exceeds 150° C.,
the surface of the plastic film becomes soft, whereby damage is more
likely to be caused to the film surface when being moved in the vacuum
chamber. On the contrary, if the temperature is below 40° C., the
conductive thin film with great hardness cannot be readily obtained.
For control of the roll temperature, a water passage may be provided in the
roll in which a temperature-adjusted heating medium is fed. Although not
particularly limited, as the heating medium, it is suitable that water,
oil, ethylene glycol, or propylene glycol may be used independently or in
combination.
To produce a transparent conductive thin film with great hardness, it is
important to reduce the impurity such as water in the ambient for film
formation as much as possible.
If the film is formed by sputtering, preferably, the pressure in a vacuum
chamber is decreased down to 1.110 Pa or lower before sputtering, and then
an inactive gas such as Ar and a reactive gas such as oxygen are
introduced to the vacuum chamber. Then, discharge electricity is generated
with a pressure ranging from 0.01-10 Pa for sputtering. This applies to
other methods such as vapor deposition, CVD, and the like.
As described above, the transparent conductive film having the transparent
conductive thin film with excellent quality and great hardness is obtained
by reducing the impurities such as moisture in the ambient for film
formation as much as possible. Thus, when the transparent conductive thin
film is used for a touchpanel, degradation of the transparent conductive
thin film is not seen after 100,000 linear-sliding test with a load of
5.0N with use of a polyacetal pen (leading edge: 0.8 mmR).
Further, to provide the transparent conductive thin film with greater
hardness, energy may be applied after film formation by means of, e.g.,
heating or ultraviolet irradiation. Among these energy applying methods,
heating in an oxygen ambient is suitable.
The heating temperature is preferably 150-200° C. If the temperature
is below 150° C., the effect of improving the film is insufficient.
On the contrary, if the temperature exceeds 200° C., planarity of
the film is not readily maintained, and the degree of crystallization of
the transparent conductive thin film becomes extremely high, thereby
resulting in a fragile transparent conductive thin film.
The heating time is preferably 0.2-60 minutes. If the heating time is
shorter than 0.2 minutes, the effect of improving the film is insufficient
even with a high temperature of about 220° C. The heating time that
is longer than 60 minutes is industrially unsuitable.
The ambient for heating is preferably obtained by preliminary evacuating a
space to achieve a pressure of at most 0.2 Pa and then filling the space
with oxygen. The pressure at the time is preferably at most the
atmospheric pressure.
To provide the outermost layer (pen input surface) with greater resistance
to damage when used for a touchpanel, a hardcoat layer is preferably
provided on the opposite side (the pen input surface of the outermost
layer when used for the touchpanel) of the surface on which the
transparent conductive thin film of the transparent plastic film is
formed. Preferably the hardcoat layer has a hardness of at least 2 H of a
pencil hardness. The hardness smaller than 2 H is insufficient in terms of
resistance to damage as a hardness of the hardcoat layer.
Preferably, the hardcoat layer has a thickness of 0.5-10 µm. If the
thickness is smaller than 0.5 µm, resistance to damage is
unsatisfactory. The thickness greater than 10 µm is not preferable in
terms of productivity.
The composition of the curable resin used for the hardcoat layer preferably
includes a functional group of acrylate, e.g., polyester resin, polyether
resin, acrylic resin, epoxy resin, urethane resin, alkyd resin,
spiroacetal resin, polybutadiene resin, polythiol polyene resin, oligomer
or prepolymer of, e.g., (meth)acrylate of a polyfunctional compound of,
e.g., polyvalent alcohol. The curable resin used for the hardcoat layer
further includes as a reactive diluent in a relatively large amount,
monofunctional monomer such as ethyl(meth)acrylate, ethyl
hexyl(meth)acrylate, styrene, methyl styrene, N-vinyl pyrrolidone, and/or
polyfunctional monomer such as trimethylolpropane tri(meth)acrylate,
hexanediol(meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene
glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate,
dipentaerythritol hexa(meth)acrylate, 1. 6-hexanediol di(meth)acrylate,
neopentyl glycol di(meth)acrylate.
In the present invention, urethane acrylate as an oligomer and
dipentaerythritol hexa(meth)acrylate as a monomer are mixed, for example.
In particular, a compound of polyester acrylate and polyurethane acrylate
is suitable. Polyester acrylate provides an extremely hard coating and
hence is suitable for the hardcoat layer. However, if polyester acrylate
is independently used for coating, shock-resistance tends to be low,
resulting in a fragile coating. Thus, to provide the coating with
shock-resistance and flexibility, polyurethane acrylate is used in
combination.
More specifically, with polyurethane acrylate being used in combination
with polyester acrylate, the coating is provided with greater
shock-resistance and flexibility while maintaining a hardness as a
hardcoat layer.
Polyurethane acrylate is blended in an amount of 30 parts by weight or
lower with respect to 100 parts of polyester acrylate. If the blending
amount exceeds 30 parts by weight, the coating becomes too soft and hence
shock-resistance tends to be unsatisfactory.
The composition of the above curable resin can be cured by a general curing
method, i.e., heating, electron ray irradiation or ultraviolet
irradiation. For example, in the case of electron ray irradiation,
electron rays with an energy of 50-1000 keV, and preferably 100-300 keV,
is emitted from various electron ray accelerators of, e.g., a
Cockcroft-Walton type, Van de Graatt type, resonance transformation type,
insulating core transformer type, linear type, Dynamitron type, and high
frequency type. In the case of ultraviolet ray irradiation, ultraviolet
rays emitted from ultra-high pressure mercury lamp, high voltage mercury
lamp, low-voltage mercury lamp, carbon arc, xenon arc, and metal halide
lamp may be used.
Further, in the case of ionizing
radiation for curing, as a photo
polymerization initiator, acetophenones, benzophenones, Michler's benzoyl
benzoate, α-amyloxyme ester, tetramethylthiuram monosulfide
thioxanthenes or the like is preferably blended in the composition of the
curable resin, and as a photosensitizer, n-butylamine, triethylamine,
tri-n-butylphosphines or the like is preferably blended. In the present
invention, it is particularly preferable to blend urethane acrylate as an
oligomer and to blend dipentaerythritol hexa(meth)acrylate as a monomer.
To give anti-glare properties to the hardcoat layer, it is effective to
disperse inorganic particles of, e.g., CaCO
3 or SiO
2 in the
curable resin, or form irregularities over the surface of the hardcoat
layer. For example, to provide irregularities, after coating a liquid
containing a composition of curable resin, an embossing film having
protrusions over the surface is laminated and ultraviolet rays are
directed from above the embossing film to cure the curable resin, and then
only the embossing film is removed.
As the above mentioned embossing film, a base film of for example
polyethylene terephthalate (hereinafter abbreviated as PET) having
releasability with desired protrusions, or a base film of for example PET
having a layer with fine protrusions may be used. The protruding layer may
be obtained by coating a resin composition of inorganic particles and
binder resin on the base film. For the binder resin, for example, acrylic
polyol crosslinked by polyisocyanate is used. As the inorganic particle,
CaCO
3 or SiO
2 may be used. Further, PET of a mat type mixed with
inorganic particles of for example SiO
2 at the time of PET
fabrication may be used.
When the coating of the ultraviolet-curable resin is laminated with the
embossing film and then ultraviolet rays are directed to cure the coating,
in the case of the base film having PET as the embossing film, the short
wavelength side of the ultraviolet rays is absorbed by the film, so that
the ultraviolet-curable resin would not be fully cured. Thus, the
embossing film which is laminated on the coating of the
ultraviolet-curable resin must have a transmittance of at least 20%.
In order to further improve transmittance of visible rays when used for the
touchpanel, a treatment for low reflection may be performed on the
hardcoat layer. In the treatment for low reflection, a material having a
refractive index which differs from that of the hardcoat layer is
preferably layered in a single form or in a structure of at least two
layers. In the case of the single layer, a material having a refractive
index smaller than that of the hardcoat layer is preferably used. In the
case of a multilayer structure of at least two layers, the layer which is
adjacent to the hardcoat layer has a material having a refractive index
greater than that of the hardcoat layer, and a material having a
refractive index smaller than that of the hardcoat layer is used for the
layer thereabove. The material used for the treatment for low reflection
is not particularly limited insofar as it satisfies the conditions of the
above refractive indices and may be either an organic or inorganic
material. For example, a dielectric material of, e.g., CaF
2,
MgF
2, NaAlF
4, SiO
2, ThF
4, ZrO
2, Nd
2 O
3,
SnO
2, TiO
2, CeO
2, ZnS, or In
2 O
3, is preferably
used.
The treatment for low reflection may be a dry coating process such as
vacuum deposition, sputtering, CVD, ion plating, or a wet coating process
such as gravure method, reverse method, or die coating method.
Prior to a process of treatment for low reflection, well known finishing
processes such as corona discharge, plasma treatment, sputter etching,
electron beam irradiation, ultraviolet ray irradiation, primer treatment,
or soft adhesion treatment may be performed on the hardcoat layer.
The use of the transparent conductive film of the present invention that is
layered on the transparent resin sheet with a tackifier on the surface
without the transparent conductive thin film provides a transparent
conductive layer sheet for a fixed electrode of the touchpanel. Namely,
the use of resin for the fixed electrode rather than glass enables
manufacture of a touchpanel which is light in weight and which does not
easily break up.
Although not particularly limited insofar as provided with transparency,
for the tackifier, acrylic adhesive, silicone adhesive, rubber adhesive or
the like is suitable. Although the thickness of the tackifier is not
particularly limited, it is generally desirable that the thickness is
1-100 µm. If the thickness of the tackifier is smaller than 1 µm,
practical adhesion is not easily obtained. The thickness exceeding 100
µm is not preferable in terms of productivity.
The transparent resin sheet applied through the tackifier is used for the
purpose of giving a mechanical strength equivalent to that of glass. The
thickness of the transparent resin sheet is preferably 0.05-5.0 mm. The
thickness of the transparent resin sheet smaller than 0.05 mm is
insufficient in mechanical strength as compared with glass. The thickness
exceeding 5.0 mm is too thick to be used for a touchpanel. The material of
the transparent resin sheet may be the same as that of the transparent
plastic film.
FIG. 13 shows an exemplary touchpanel with a transparent conductive film
(10) of the present invention. In the touchpanel having a pair of panel
plates that has transparent conductive film (10) including a cured layer
(12) and a transparent conductive thin film (13) layered on a transparent
plastic film (11), arranged through a spacer (20), e.g., a bead, such that
the transparent conductive thin films are opposite each other, the
transparent conductive film (10) of the present invention is used for one
of the panel plates. Note that a hardcoat layer (14) is layered on the
side of transparent plastic film (11) that is opposite to cured layer
(12). In the touchpanel, when a character is input by a pen, the pressure
of the pen brings the opposite transparent conductive thin films to be in
contact with each other, so that the device is electrically turned on for
detecting the position of the pen over the touchpanel. By successively and
precisely detecting the position of the pen, characters can be recognized
with movement of the pen. At the time, if the transparent conductive film
of the present invention is used for a movable electrode on the side in
which the pen is used, excellent resistance to pen input is provided,
whereby the touchpanel can be stably used over a long period of time.
Note that FIG. 14 shows a cross sectional view of a plastic touchpanel not
provided with a glass substrate obtained by using transparent conductive
film (10) and transparent conductive sheet (40) of the present invention.
Since the plastic touchpanel does not use glass plate (30) in FIG. 13, it
is extremely light in weight and has sufficient shock-resistance. Here,
transparent resin sheet (42) of transparent conductive sheet (40) and
transparent plastic film (11) are bonded by a tackifier.
EXAMPLES
The present invention will now be described in further detail with
examples. The present invention is not limited by the examples. Note that
the test for determining performance of the transparent conductive film
and resistance to pen input of the touchpanel was conducted in the
following way.
<Light Ray Transmittance and Haze>
In accordance with JIS-K7105, NDH-1001DP manufactured by Nippon Denshoku
Industries Co., Ltd. was used for measuring light ray transmittance and
haze.
<Surface Resistance>
In accordance with JIS-K7194, measurement was carried out by 4-terminal
method. For the measurement, a Lotest AMCP-T400 manufactured by Mitsubishi
Oil Co., Ltd. was used.
<Number of Protrusions over Surface>
Using a scanning
electron microscope (S-800 manufactured by Hitachi, Ltd.),
the surface of the film on the side of the transparent conductive thin
film was observed. The picture of the film surface was taken to determine
the number of protrusions per 100 µm
2 over the film surface at ten
positions, and the average value was determined as the number of
protrusions.
<Diameter and Height of Protrusion>
The diameter and height of the protrusion over the surface of the film on
the side of the transparent conductive thin film was measured with use of
a scanning probe microscope (SPA300 manufactured by Seiko Instruments).
Measurement was performed for 50 protrusions, and the average value was
determined. For a scanner, a 100 micron scanner was used and atomic force
microscope observation was carried out under the following conditions.
Cantilever: SI-DF3 (silicon spring constant: about 2N/m).
Scan mode: DFM mode
Scan speed: 0.5-2.0 Hz
Pixel number: 512 pixels×256 pixels
Measuring environment: ambient (temperature 20° C.×moisture
content 65% RH)
<Coefficient of Dynamic Friction>
In accordance with JIS-P8147, the coefficient of dynamic frictions of the
surface of ITO of glass (a 450 Ω/.sunburst. product manufactured by
Nippon Soda Co., Ltd.) obtained by layering an indium-tin oxide compound
(ITO) thin film and the transparent conductive thin film of the
transparent conductive film of the present invention were measured with a
load of 43.1N (4.4 kgf) at a drawing speed of 200 m/min.
<Volatile Component Amount>
The transparent conductive film weighing 3 g was cut into strips each
having a size of 3 cm×0.5 cm. The strips were subjected to a heating
and elimination process in He for 15 minutes at 100° C. using a
solid purge and trap apparatus (JHS-100 manufactured by Japan Analytical
Industry Co., Ltd.). The eliminated component was cold-trapped to an
adsorbent (quartz wool) which had been cooled by a liquid nitrogen, and
then introduced to GC-MS apparatus (HP6890 and HP5973 manufactured by
Hewlett-Packard Co.) by rapidly heating. Then, the volatile component
amount in the transparent conductive film was determined.
<Adherence Measurement>
An ionomer film with a thickness of 40 µm was laminated onto a
polyethylene terephthalate film with a thickness of 75 µm using a
polyester adhesive to provide a layered stack for adherence measurement.
The ionomer surface of the layered stack for adherence measurement and the
transparent conductive thin film surface of the transparent conductive
film were placed opposite each other and heat-sealed at 130° C. The
layered stack for adherence measurement and the transparent conductive
film were separated by a 180° degree peeling method and the peeling
strength force was determined as an adherence. Then, the separation speed
was 1000 mm/min.
<Test for Endurance to Pen Input>
A load of 5.0N was applied to a polyacetal pen (leading edge: 0.8 mmR) to
perform a 100,000 (50, 000 round trips) sliding test on the touchpanel.
Then, a sliding distance was 30 mm and a sliding speed was 60 mm/second.
After the endurance test, visible inspection was performed to see if the
sliding portion was subjected to whitening. Further, a circle having a
size of 20 mmφ was written with a pen load of 0.5N on the sliding
portion, and it was evaluated if the touchpanel could correctly read the
circle. Further, an ON resistance (a resistance value when the movable
electrode (film electrode) and the fixed electrode are in contact) was
measured when the sliding portion was pressed with a pen load of 0. 5N.
<Average Molecular weight>
Polyester resin in an amount of 0.03 g was dissolved in 10 ml
tetrahydrofuran. Measurement was carried out using a GPC-LALLS apparatus
low angle light scattering photometer LS-8000 (tetrahydrofuran solvent,
reference: polystyrene manufactured by Tosoh Corporation).
<Hardness of Transparent Conductive Thin Film Surface of Transparent
Conductive Film>
A sample of transparent conductive film was cut into pieces each having a
size of 7 mm×7 mm and the side opposite to the transparent
conductive thin film was fixed to an aluminum sample holder by a 2-liquid
mixture epoxy adhesive. Using a Nano Indenter XP (manufactured by Toyo
Corporation), the transparent conductive thin film surface of the
transparent conductive film was measured for hardness by a continuous
rigidity measuring method with the following load excitation. For an
indenter, an AccuTip type Burcovitch diamond chip having a curvature
radius of 40 nm was used.
(1) Surface Detection
The indenter was lowered to the transparent conductive thin film surface of
the transparent conductive film at a speed of 20 nm/second, and the
portion with a rigidity 1.5 times that during free oscillation (in
atmosphere) was determined as a surface.
(2) Process of Applying Load
With a loading rate of (dF/dt)/F=0.05 (F: load), the load was subjected to
oscillation modulation at 45 Hz. In addition, the indenter was pushed in
down to a depth of 200 nm.
(3) Process of Removing Load
A constant load was maintained for 15 minutes, and then 80% of the maximum
load was removed at a speed that is 70% the ultimate speed in the load
applying process.
(4) Drift Detection
50 points were measured for displacement every two seconds with a load that
is 20% the maximum load, and the drift speed was calculated. Using the
result, a load-displacement curve was modified.
After the completion of the above measurement, the effective contact depth
of the indenter was calculated using a method of Oliver & Pharr. A
preliminary obtained indenter shape correcting expression is applied to
find an effective contact projective cross sectional area. The load at
each measuring point was divided by the area to find hardness (GPa).
The central portion of the sample was measured at 10 points, at intervals
of 40 µm, of which average value was determined. A maximum hardness was
found by a graph of the hardness and depth, of which third decimal place
was rounded off to obtain hardness (GPa) of the transparent conductive
thin film of the transparent conductive film.
FIG. 26 is a graph showing a hardness and indentation fracture depth of the
transparent conductive thin film surface of the fourteenth example. The
hardness of the thin film of this case is 0.51 GPa.
<Determination of Transparent Conductive Thin Film for Crystallinity>
The transparent conductive film was soaked in 1, 1, 1, 3, 3,
3-hexafluoroisopropanol, and a plastic film and cured polymeric layer were
dissolved to provide a single film of a transparent conductive thin film.
Thereafter, the transparent conductive thin film in the solution was
placed on a MicroGrid and the solution was allowed to stay for air drying
for a day. The dried sample was measured for the electron diffraction
image by a transmission electron microscope (JEM-2010). The electron ray
had an accelerating voltage of 200 kV and a wavelength of 0.0025 nm. Based
on the electron diffraction image, it was determined if the transparent
conductive thin film was crystalline or amorphous.
Effect of a configuration of transparent conductive film or the like
(Examples 1-8, Comparative Examples 1-4).
Examples 1-3 and Comparative Examples 1 and 2
Copolymer polyester resin (Byron 200, average molecular weight: 18,000
manufactured by Toyobo Co., Ltd.) was blended in an amount shown in Table
1 with respect to 100 parts of acrylic resin containing photo
polymerization initiator (Seika beam EXF-01J, manufactured by
Dainichiseika Color & Chemicals Mfg. Co., Ltd.) and a mixture solvent of
toluene/MEK (8/2; weight ratio) was added as a solvent to provide solid
content concentration of 50% by weight to prepare a coating by agitation
and uniform dissolution. The prepared coating was applied in the thickness
of 5 µm on an adhesive layer of a biaxially oriented polyethylene
terephthalate film (A4140, thickness: 188 µm manufactured by Toyobo
Co., Ltd.) having a soft adhesion layer on one surface and dried for one
minute at 80° C. Then, ultraviolet rays (light amount: 300
mJ/cm
2) were directed by ultraviolet irradiation apparatus
(UB042-5AM-W type, manufactured by Eyegraphics, Co.) and the coating was
cured.
Then, a transparent conductive thin film made of an indium-tin oxide
compound was formed on the cured layer. At the time, DC electric power of
2.0 W/cm
2 was applied using an indium oxide containing a tin oxide in
an amount of 10% by weight as a target (density: 7.1 g/cm
3,
manufactured by Mitsui Kinzoku Co.). In addition, an Ar gas was introduced
at a flow of 130 sccm, and an O
2 gas was introduced at a flow of 10
sccm, so that a film was formed by DC magnetron sputtering in an ambient
of 0.40 Pa. However, general DC was not performed and, rather, a pulse
having a width of 5 µs at +20 V was applied with a period of 50 kHz. In
addition, sputtering was performed with the film being cooled by a cooling
roll at -10° C. Further, while always observing an oxygen partial
pressure of the ambient by a sputter process monitor (SPM200, manufactured
by Hakuto Co., Ltd.), the oxygen gas was fed back to a flow meter and DC
power supply source such that an oxidation degree in the indium-tin oxide
compound could be kept at a constant value. Thus, a transparent conductive
thin film of the indium-tin oxide compound with a thickness of 27 nm was
deposited.
Further, the transparent conductive film was used as one panel plate, and a
transparent conductive thin film of an indium-tin oxide compound (tin
oxide content: 10% by weight) with a thickness of 20 nm formed by plasma
CVD on the glass substrate was used as the other panel plate. Two panel
plates were arranged such that the transparent conductive thin films were
arranged opposite each other with an epoxy bead having a diameter of 30
µm interposed to provide a touchpanel.
Fourth Example
A transparent conductive thin film of a tin-antimony oxide compound was
formed on a transparent plastic film base/cured layer of the second
example. At the time, DC power of 1.5 W/cm
2 was applied using as a
target (density: 5.7 g/cm
3) an indium oxide containing antimony oxide
in an amount of 5% by weight. An Ar gas was introduced at a flow of 130
sccm and an O
2 gas was introduced at a flow of 20 sccm, so that a
film was formed by DC magnetron sputtering in an ambient of 0.40 Pa. Note
that, general DC was not performed, but a pulse with a width of 5 µs at
+20 V was applied with a period of 100 kHz to prevent arc discharge.
Further, by cooling the film with a cooling roll at -10° C.,
sputtering was performed. While always observing by a sputter process
monitor (SPM200, manufactured by Hakuto Co.) the oxygen partial pressure
of the ambient, the oxygen gas was fed back to a flow meter and DC power
supply source such that an oxidation degree in the indium-tin oxide
compound could be kept at a constant value. Thus, a transparent conductive
thin film of a tin-antimony oxide compound with a thickness of 30 nm was
deposited.
The test result for performance of the obtained transparent conductive film
is shown in Table 1. As in the second example, a touchpanel was
manufactured.
Fifth Example
An ultraviolet curable resin (EXG, manufactured by Dainichiseika Color &
Chemicals Mfg. Co., Ltd.) of a mixture of polyester acrylate and
polyurethane acrylate was applied by a gravure reverse method to form a
film with thickness of 5 µm (when dried) as a hardcoat layer resin on
the side opposite the cured layer surface of a stack including a
transparent plastic film base/cured layer of the second example, and the
solvent was dried. Thereafter, it was transported at a speed of 10 m/min
below an ultraviolet irradiation apparatus of 160 W to cure the
ultraviolet curable resin, so that a hardcoat layer was formed.
As in the fourth example, a tin-antimony oxide compound was formed on the
cured layer of a stack including the hardcoat layer/transparent plastic
film base/cured layer. With use of the transparent conductive film, a
touchpanel was manufactured as in the second example.
Sixth Example
As in the second example, a stack of the transparent plastic film
base/cured layer was manufactured. On the side opposite the cured layer of
the stack, as hardcoat layer resin, an ultraviolet curable resin (EXG
manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) of a
mixture of polyester acrylate and polyurethane acrylate was applied by a
gravure reverse method to have a thickness of 5 µm (when dried), and
the solvent was dried. Thereafter, a mat embossing film (X, manufactured
by Toray Industries, Inc.) was laminated such that the mat surface was
brought into contact with the ultraviolet curable resin, which film was of
a polyethylene terephthalate film having fine protrusions over its
surface. The surface of the mat embossing film had an average surface
roughness of 0.40 µm, and average interval of protrusions of 160 µm
and maximum surface roughness of 25 µm. Thus obtained laminated film
was transported below the ultraviolet irradiation apparatus of 160 W at a
speed of 10 m/min to cure the ultraviolet curable resin. Thereafter, the
mat embossing film was separated to form a hardcoat layer with recesses
over its surface and having an anti-glare effect.
As in the fourth example, a transparent conductive thin film of a
tin-antimony oxide compound thin film was formed on the cured layer of a
stack including the anti-glare hardcoat layer/transparent plastic film
base/cured layer. In addition, the transparent conductive film was used as
one panel plate, and a touchpanel was manufactured as in the second
example.
Seventh Example
As in the sixth example, a stack of the anti-glare hardcoat
layer/transparent plastic film base/cured layer/transparent conductive
thin film layer was manufactured. Then, TiO
2 (refractive index: 2.30,
thickness: 15 nm), SiO
2 (refractive index: 1.46, thickness: 29 nm),
TiO
2 (refractive index: 2.30, thickness: 109 nm), and SiO
2
(refractive index: 1.46, thickness: 87 nm) were successively layered on
the anti-glare hardcoat layer to form an antireflection layer. To form a
TiO
2 thin film, titanium was used as a target, and Ar and O
2
gases were respectively introduced at flow speeds of 500 sccm and 80 sccm
with a vacuum of 0.27 Pa by direct current magnetron sputtering. With a
cooling roll having a surface temperature of 0° C. being provided
on the back surface of the substrate, the transparent plastic film was
cooled. At that time, power of 7.8 W/cm
2 was supplied to the target,
and a dynamic rate was 23 nm.multidot.m/min.
The SiO
2 thin film was formed by direct current magnetron sputtering
using silicon as a target, with the vacuum maintained at 0.27 Pa and Ar
and O
2 gases were respectively introduced at flow speeds of 500 sccm
and 80 sccm. The cooling roll at 0° C. was provided at the back
surface of the substrate and the transparent plastic film was cooled.
Electric power of 7.8 W/cm
2 was supplied to the target, and a dynamic
rate was 23 nm.multidot.m/min. The transparent conductive film was used as
one panel plate and a touchpanel was manufactured as in the second
example.
Eighth Example
The transparent conductive film manufactured as in the fourth example was
attached to a polycarbonate sheet having a thickness of 1.0 mm through
acrylic tackifier to provide a transparent conductive layered stack sheet.
The transparent conductive layered stack sheet was used as a fixed
electrode, and the transparent conductive film of the sixth example was
used as a movable electrode to manufacture a touchpanel as in the second
example.
Third Comparative Example
A cured layer containing silica fine particles was manufactured instead of
a polyester resin. Monodispersed silica fine particles (SEAHOSTAR KE-P150,
manufactured by Nippon Shokubai Co., Ltd.) having an average particle size
of 1.5 µm was added in an amount of 0.5 parts by weight with respect to
100 parts of acrylic resin (Seika beam EXF-01J, manufactured by
Dainichiseika Color & Chemicals Mfg. Co., Ltd.) containing a photo
polymerization initiator, while toluene is added in an amount of 80 parts
by weight as a solvent, which is then agitated to prepare a coating with
uniformly dispersed silica fine particles. The prepared coating was
applied using a Meyer bar to have a thickness of 5 µm on the adhesive
layer of a biaxially oriented polyethylene terephthalate film (A4140,
thickness 188 µm, manufactured by Toyobo Co., Ltd.) having a soft
adhesion layer on one surface, which is dried for one minute at 80°
C. Thereafter, ultraviolet rays (light amount: 300 mJ/cm
2) were
directed to cure the coating using the ultraviolet irradiation apparatus
(UB042-5AM-W type, manufactured by Eyegraphics, Co.). A tin-antimony oxide
compound thin film was formed as in the fourth example on the resultant
cured layer of the transparent plastic film base. Further, using the
transparent conductive film, a touchpanel was manufactured as in the
second example.
Fourth Comparative Example
An alcohol solution (concentration: 1% by weight) of a mixture of butanol
and isopropanol of an organosilicon compound was applied to the adhesive
layer of the biaxially drawn polyethylene terephthalate film (A4140,
thickness: 188 µm, manufactured by Toyobo Co., Ltd.) having on its one
surface a soft adhesion layer as in the first example and dried for one
minute at 100° C. Then, using an indium-tin alloy target containing
tin oxide in an amount of 5% by weight, a film was formed on the
organosilicon compound with a substrate temperature of 120° C. The
vacuum was 0.27 Pa, and Ar and O
2 gases were respectively introduced
at flow rates of 130 sccm and 40 sccm. Power of 1.5 W/cm
2 was applied
to the target. After the film formation, a heat treatment is performed at
150° C. for ten minutes to provide a crystalline indium-tin oxide
compound thin film. With use of the transparent conductive film, a
touchpanel was manufactured as in the second example.
The measurement results of the foregoing examples and comparative examples
are shown in Table 1 and in FIGS. 1 to 12. FIG. 15 shows a surface
configuration observed by a scanning type electronic microscope over the
transparent conductive thin film surface of the transparent conductive
film in the fourth example.
As is apparent from the result shown in Table 1, the transparent conductive
films of the present invention having a specific number of protrusions
with specific configuration (diameter and height) over the transparent
conductive thin film surface according to the first to eighth examples
exhibited low Haze values and good transparency. Further, since the
touchpanel using the transparent conductive film is superior in
slidability because of its protrusions over the surface, even after
100,000 sliding test with a load of 5.0N using a polyacetal pen (leading
edge: 0.8 mmR), whitening did not occur at a sliding portion (denoted by
reference numeral 1 in FIGS. 1 to 8) and an ON resistance was not
deteriorated. In addition, the input circle mark was properly recognized.
On the other hand, the transparent conductive film of the first comparative
example had protrusions of the transparent conductive thin film with a
diameter, height and the number which are all smaller than the lower
limits of the present invention. As such, although it had excellent
transparency, because of its poor slidability due to protrusions, when
used for the touchpanel, whitening occurred at the sliding portion
(reference numeral 1 in FIG. 9) after 100,000 sliding test with a load of
5.0N using a polyacetal pen (leading edge: 0.8 mmR), and an ON resistance
increased. In addition, the input circle mark was not properly recognized
at the sliding portion.
The transparent conductive film of the second comparative example with
protrusions of the transparent conductive thin film having a diameter,
height and the number which are all greater than the upper limits of the
present invention was inferior in transparency and exhibited a high haze
value.
The transparent conductive film of the third comparative example with
silica particles added to the cured layer exhibited a high haze value,
extremely large protrusions and inferior slidability. Thus, when used for
the touchpanel, whitening occurred at the sliding portion (reference
numeral 1 in FIG. 11) after 100,000 sliding test with a load of 5.0N using
a polyacetal pen (leading edge: 0.8 mmR), and an ON resistance increased.
In addition, the input circle mark was not properly recognized at the
sliding portion.
When the crystalline indium-tin oxide compound thin film was used and the
transparent conductive film of the fourth comparative example not having
protrusions over the transparent conductive thin film surface was used for
the touchpanel, whitening was not observed at the sliding portion
(reference numeral 1 in FIG. 12) after 100,000 sliding test with a load of
5.0N using a polyacetal pen (leading edge: 0.8 mmR), but an ON resistance
increased. In addition, the input circle mark was not properly recognized
at the sliding portion. This is because the sidability was deteriorated
since the transparent conductive thin film surface did not have any
protrusion and cracks occurred by the sliding test.
TABLE 1
Composition of cured layer
(parts by weight)
Acrylic resin
containing Protrusion over transparent
Transparent conductive film Endurance test by pen input
photo conductive thin film surface
Surface Coeffi- Initial
poly- Poly- Silica Dia- Number Light
resis- cient of Whitening resis- ON
merization ester fine meter Height (number/ transmit-
Haze tance dynamic at sliding tance resistance
initiator resin particle (µm) (µm) 100 µm2)
tance (%) (%) (Ω/.quadrature.) friction portion (kΩ)
after test
Example 1 100 0.20 -- 0.20 0.010 10 88.3
0.80 450 3 None 2.0 2.0
Example 2 100 3.0 -- 0.80 0.030 60 88.1
1.2 450 0.8 None 2.0 2.0
Example 3 100 9.0 -- 2.5 0.150 150 87.9
1.7 450 0.5 None 2.0 2.0
Comparative 100 0.05 -- 0.04 0.004 2 88.2
0.50 450 9 Yes 2.0 500
example 1
Comparative 100 30 -- 3.5 2.50 300 87.6
15 450 0.1 None 2.0 2.1
example 2
Example 4 100 3.0 -- 0.80 0.030 60 87.7
1.2 1500 0.8 None 2.8 2.8
Example 5 100 3.0 -- 0.80 0.030 60 88.0
1.2 1500 0.8 None 2.8 2.8
Example 6 100 3.0 -- 0.80 0.030 60 87.3
4.8 1500 0.8 None 2.8 2.8
Example 7 100 3.0 -- 0.80 0.030 60 91.9
4.8 1500 0.8 None 2.8 2.8
Example 8 100 3.0 -- 0.80 0.030 60 87.3
1.4 1500 0.8 None 2.8 2.8
Example 3 100 -- 0.5 4.0 1.00 2 87.1
4.2 1500 8 Yes 2.8 >1000
Example 4 100 -- -- -- -- -- 87.8
0.90 400 7 None 2.0 3.0
Ninth Example
Copolymer polyester resin (Byron 200, average molecular weight: 18,000,
manufactured by Toyobo Co., Ltd.) was blended in an amount of 3 parts by
weight with respect to 100 parts of acrylic resin containing photo
polymerization initiator (Seika beam EXF-01J, manufactured by
Dainichiseika Color & Chemicals Mfg. Co., Ltd.) and a mixture solvent of
toluene/MEK (8/2; weight ratio) was added as a solvent to provide solid
content concentration of 50% by weight to prepare a coating by agitation
and uniform dissolution. The prepared coating was applied to have a
thickness of 5 µm on an adhesive layer of a biaxially oriented
polyethylene terephthalate film (A4340, thickness: 188 µm manufactured
by Toyobo Co., Ltd.) using a Meyer bar, which was then dried for one
minute at 80° C. Thereafter, ultraviolet rays (light amount: 300
mJ/cm
2) were directed by ultraviolet irradiation apparatus
(UB042-5AM-W type, manufactured by Eyegraphics, Co.) and the coating was
cured. Then, a heat treatment was performed at 180° C. for one
minute to reduce volatile component.
To perform vacuum exposure on the plastic film with the cured layer, a
rollback process was performed in a vacuum chamber. The pressure at the
time was 0.002 Pa and the exposure time was 10 minutes. The temperature of
the center roll was 40° C.
Then, a transparent conductive a transparent conductive thin film made of
an indium-tin oxide compound was formed on the cured layer. At the time,
DC electric power of 2 W/cm
2 was applied using a tin oxide in an
indium oxide in an amount of 5% by weight as a target (density: 7.1
g/cm
3, manufactured by Mitsui Kinzoku Co.). In addition, an Ar gas
was introduced at a flow of 130 sccm, and an O
2 gas was introduced at
a flow of 10 sccm, so that a film was formed by DC magnetron sputtering in
an ambient of 0.4 Pa. However, general DC was not performed and, rather, a
pulse having a width of 5 µs with a period of 50 kHz was applied with
use of PRG-100 manufactured by ENI Japan to prevent arc discharge. In
addition, sputtering was performed with the temperature of the center roll
maintained at 20° C.
Further, while always observing an oxygen partial pressure of the ambient
by a sputter process monitor (SPM200, manufactured by Hakuto Co., Ltd.),
the oxygen gas was fed back to a flow meter and DC power supply source so
that an oxidation degree in the indium-tin oxide compound could kept at a
constant value. Thus, a transparent conductive thin film of the indium-tin
oxide compound with a thickness of 22 nm was deposited. Further, a
touchpanel was manufactured using thus obtained transparent conductive
film as in the first example.
Tenth Example
An ultraviolet curable resin (EXG, manufactured by Dainichiseika Color &
Chemicals Mfg. Co., Ltd.) of a mixture of polyester acrylate and
polyurethane acrylate was applied by a gravure reverse method to form a
film with thickness of 5 µm when dried as a hardcoat layer resin on the
side opposite the cured layer surface of a stack including a transparent
plastic film base/cured layer of the ninth example, and the solvent was
dried. Thereafter, it was transported at a speed of 10 m/min below an
ultraviolet irradiation apparatus of 160 W to cure the ultraviolet curable
resin, so that a hardcoat layer was formed. Then, a heat treatment was
performed at 180° C. for one minute to reduce volatile component.
As in the ninth example, a indium-tin oxide compound was formed on the
cured layer of a stack including the hardcoat layer/transparent plastic
film base/cured layer. With use of the transparent conductive film, a
touchpanel was manufactured as in the first example.
Eleventh Example
As in the ninth example, a stack of the transparent plastic film base/cured
layer was manufactured. On the side opposite the cured layer of the stack,
as hardcoat layer resin, an ultraviolet curable resin (EXG manufactured by
Dainichiseika Color & Chemicals Mfg. Co., Ltd.) of a mixture of polyester
acrylate and polyurethane acrylate was applied by a gravure reverse method
to have a thickness of 5 µm when dried, and the solvent was dried.
Thereafter, a mat embossing film (X, manufactured by Toray Industries,
Inc.) was laminated such that the mat surface was brought into contact
with the ultraviolet curable resin, which film was of a polyethylene
terephthalate film having fine protrusions over its surface. The surface
of the mat embossing film had an average surface roughness of 0.40 µm,
and average interval of protrusions of 160 µm and maximum surface
roughness of 25 µm.
Thus laminated film was transported below the ultraviolet irradiation
apparatus of 160 W at a speed of 10 m/min to cure the ultraviolet curable
resin. Thereafter, the mat embossing film was separated to form a hardcoat
layer with recesses over its surface and having an anti-glare effect.
Thereafter, a heat treatment was performed at 180° C. for one
minute to reduce volatile component.
As in the ninth example, a transparent conductive thin film of an
indium-tin oxide compound thin film was formed as a transparent conductive
thin film on the cured layer of a stack including the anti-glare hardcoat
layer/transparent plastic film base/cured layer. In addition, the
transparent conductive film was used as one panel plate, and a touchpanel
was manufactured as in the first example.
Twelfth Example
As in the eleventh example, a stack of the anti-glare hardcoat
layer/transparent plastic film base/cured layer/transparent conductive
thin film layer was manufactured. Then, TiO
2 (refractive index: 2.30,
thickness: 15 nm), SiO
2 (refractive index: 1.46, thickness: 29 nm),
TiO
2 (refractive index: 2.30, thickness: 109 nm), and SiO
2
(refractive index: 1.46, thickness: 87 nm) were successively layered on
the anti-glare hardcoat layer to form an antireflection layer. To form a
TiO
2 thin film, titanium was used as a target, and Ar and O
2
gases were respectively introduced at flow speeds of 500 sccm and 80 sccm
with a vacuum of 0.27 Pa by direct current magnetron sputtering. With a
cooling roll having a surface temperature of 0° C. being provided
on the back surface of the substrate, the transparent plastic film was
cooled. At that time, power of 7.8 W/cm
2 was supplied to the target,
and a dynamic rate was 23 nm.multidot.m/min.
The SiO
2 thin film was formed by direct current magnetron sputtering
using silicon as a target, with the vacuum maintained at 0.27 Pa and Ar
and O
2 gases were respectively introduced at flow speeds of 500 sccm
and 80 sccm. The cooling roll at 0° C. was provided at the back
surface of the substrate and the transparent plastic film was cooled.
Electric power of 7.8 W/cm
2 was supplied to the target, and a dynamic
rate was 23 nm.multidot.m/min. The transparent conductive film was used as
one panel plate and a touchpanel was manufactured as in the first example.
Thirteenth Example
The transparent conductive film manufactured as in the ninth example was
attached to a polycarbonate sheet having a thickness of 1.0 mm through
acrylic tackifier to provide a transparent conductive layered stack sheet.
The transparent conductive layered stack sheet was used as a fixed
electrode, and the transparent conductive film of the sixth example was
used as a movable electrode to manufacture a touchpanel as in the first
example.
Example 9A
A transparent conductive film was manufactured as in the ninth example
except for a heat treatment at 180° C. for one minute and a process
of vacuum exposure for reducing volatile component. Further, with use of
the transparent conductive film, a touchpanel was manufactured as in the
first example.
The measurement results of the above described tenth to thirteenth examples
as well as example 9A are shown in Table 2, and output shapes of the ninth
to thirteenth examples are shown in FIGS. 16 to 20.
Referring to Table 2, the transparent conductive films of the ninth to
thirteenth examples provides transparent conductive thin films of good
quality with reduced amount of volatile components. Whitening was not
caused to the touchpanel with the transparent conductive film even after
100,000 sliding test with a load of 5.0N using a polyacetal pen (leading
edge: 0.8 mmR), and an On resistance was not deteriorated. In addition,
the input circle mark was properly recognized.
On the other hand, in the case of example 9A, because of its large amount
of volatile component, the film had a somewhat inferior quality. When used
for the touchpanel, the sliding portion was slightly whitened after
100,000 sliding test with a load of 5.0N using a polyacetal pen (leading
edge: 0.8 mmR), and an ON resistance increased. In addition, the
recognition accuracy of the input circle mark at the sliding portion was
somewhat inferior.
TABLE 2
Volatile Test of endurance
to pen input
compo-
ON
nent Light ray Surface Whitening Initial
ON resistance
amount transmit- Haze resistance Adhesion at sliding
resistance after test
(ppm) tance (%) (%) (Ω/.quadrature.) (N/15 mm)
portion (kΩ) (k/Ω)
Example 9 0.5 88.1 1.2 250 1.5 None 2.0
2.0
Example 10 0.5 88.3 1.2 250 1.5 None 2.0
2.0
Example 11 0.5 87.5 5.9 250 1.5 None 2.0
2.8
Example 12 0.4 89.9 5.9 250 1.5 None 2.0
2.8
Example 13 0.5 87.3 1.5 250 1.5 None 2.0
2.8
Example 9A 32 87.8 1.2 250 1.5 Some 2.0
750
(Note)
There were 60 protrusions over the surface of the transparent conductive
thin film per 100 µm2 in each of the above examples each having an
diameter of 0.08 µm and height of 0.30 µm.
Effect on hardness of transparent conductive thin film
Fourteenth Example
Copolymer polyester resin (Byron 200, average molecular weight: 18,000,
manufactured by Toyobo Co., Ltd.) was blended in an amount of 3 parts by
weight with respect to 100 parts of acrylic resin containing photo
polymerization initiator (Seika beam EXF-01J, manufactured by
Dainichiseika Color & Chemicals Mfg. Co., Ltd.) and a mixture solvent of
toluene/MEK (8/2; weight ratio) was added as a solvent to provide solid
content concentration of 50% by weight, in order to prepare a coating by
agitation and uniform dissolution.
The prepared coating was applied to have a thickness of 5 µm on a
biaxially oriented PET film having on both sides soft adhesion layers
(A4340, thickness: 188 µm manufactured by Toyobo Co., Ltd.) using a
Meyer bar, which was then dried for one minute at 80° C.
Thereafter, ultraviolet rays (light amount: 300 mJ/cm
2) were directed
by ultraviolet irradiation apparatus (UB042-5AM-W type, manufactured by
Eyegraphics, Co.) and the coating was cured. Then, a heat treatment was
performed at 180° C. for one minute to reduce volatile component.
To perform vacuum exposure on the plastic film with the cured layer, a
rollback process was performed in a vacuum chamber. The pressure at the
time was 0.002 Pa and the exposure time was 10 minutes. The temperature of
the center roll was 40° C.
Then, a transparent conductive a transparent conductive thin film made of
an indium-tin oxide compound was formed on the cured layer. At the time,
DC electric power of 2 W/cm
2 was applied using a tin oxide in an
indium oxide in an amount of 5% by weight as a target (density: 7.1
g/cm
3, manufactured by Mitsui Kinzoku Co.). In addition, an Ar gas
was introduced at a flow of 130 sccm, and an O
2 gas was introduced at
a flow of 10 sccm, so that a film was formed by DC magnetron sputtering in
an ambient of 0.4 Pa. However, general DC was not performed and, rather, a
pulse having a width of 5 µs with a period of 50 kHz was applied with
use of PRG-100 manufactured by ENI Japan to prevent arc discharge. In
addition, sputtering was performed with the temperature of the center roll
maintained at 50° C.
Further, while always observing an oxygen partial pressure of the ambient
by a sputter process monitor (SPM200, manufactured by Hakuto Co., Ltd.),
the oxygen gas was fed back to a flow meter and DC power supply source
with an oxidation degree in the indium-tin oxide compound being kept at a
constant value. Thus, a transparent conductive thin film of the indium-tin
oxide compound with a thickness of 22 nm was deposited. Further, the
transparent conductive film was used as one panel, and a transparent
conductive thin film (S500 manufactured by Nippon Soda Co., Ltd) of an
indium-tin oxide compound thin film (tin oxide content: 10% by weight)
with a thickness of 20 nm formed by plasma CVD on the glass substrate was
used as the other panel plate. Two panel plates were arranged such that
the transparent conductive thin films were arranged opposite each other
with an epoxy bead having a diameter of 30 µm interposed to provide a
touchpanel.
Fifteenth Example
In the fourteenth example, an ultraviolet curable resin (EXG, manufactured
by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) of a mixture of
polyester acrylate and polyurethane acrylate was applied by a gravure
reverse method to form a film with thickness of 5 µm when dried as a
hardcoat layer resin on the side opposite the cured layer surface of a
stack including a transparent biaxially oriented PET film base/cured
layer, and the solvent was dried. Thereafter, it was transported at a
speed of 10 m/min below an ultraviolet irradiation apparatus of 160 W to
cure the ultraviolet curable resin, so that a hardcoat layer was formed.
Then, a heat treatment was performed at 180° C. for one minute to
reduce volatile component.
As in the fourteenth example, a indium-tin oxide compound thin film was
formed on the cured layer of a stack including the hardcoat
layer/transparent biaxially oriented film base/cured layer. With use of
the transparent conductive film, a touchpanel was manufactured as in the
fourteenth example.
Sixteenth Example
As in the fourteenth example, a stack of the transparent biaxially oriented
PET film base/cured layer was manufactured. On the side opposite the cured
layer of the stack, as hardcoat layer resin, an ultraviolet curable resin
(EXG manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) of a
mixture of polyester acrylate and polyurethane acrylate was applied by a
gravure reverse method to have a thickness of 5 µm when dried, and the
solvent was dried. Thereafter, a mat embossing film (X, manufactured by
Toray Industries, Inc.) was laminated such that the mat surface was
brought into contact with the ultraviolet curable resin, which film was of
a PET film having fine protrusions over its surface. The surface of the
mat embossing film had an average surface roughness of 0.40 µm, and
average interval of protrusions of 160 µm and maximum surface roughness
of 25 µm.
Thus laminated film was transported below the ultraviolet irradiation
apparatus of 160 W at a speed of 10 m/min to cure the ultraviolet curable
resin. Thereafter, the mat embossing film was separated to form a hardcoat
layer with recesses over its surface and having an anti-glare effect.
Thereafter, a heat treatment was performed at 180° C. for one
minute to reduce volatile component.
As in the fourteenth example, a transparent conductive thin film of an
indium-tin oxide compound thin film was formed as a transparent conductive
thin film on the cured layer of a stack including the anti-glare hardcoat
layer/transparent biaxially oriented PET film base/cured layer. In
addition, the transparent conductive film was used as one panel plate, and
a touchpanel was manufactured as in the fourteenth example.
Seventeenth Example
As in the sixteenth example, a stack of the anti-glare hardcoat
layer/transparent biaxially oriented PET film base/cured layer/transparent
conductive thin film layer was manufactured. Then, TiO
2 (refractive
index: 2.30, thickness: 15 nm), SiO
2 (refractive index: 1.46,
thickness: 29 nm), TiO
2 (refractive index: 2.30, thickness: 109 nm),
and SiO
2 (refractive index: 1.46, thickness: 87 nm) were successively
layered on the anti-glare hardcoat layer to form an antireflection layer.
To form a TiO
2 thin film, titanium was used as a target, and Ar and
O
2 gases were respectively introduced at flow speeds of 500 sccm and
80 sccm with a vacuum of 0.27 Pa by direct current magnetron sputtering.
With a cooling roll having a surface temperature of 0° C. being
provided on the back surface of the substrate, the transparent plastic
film was cooled. At that time, power of 7.8 W/cm
2 was supplied to the
target, and a dynamic rate was 23 nm.multidot.m/min.
The SiO
2 thin film was formed by direct current magnetron sputtering
using silicon as a target, with the vacuum maintained at 0.27 Pa and Ar
and O
2 gases were respectively introduced at flow speeds of 500 sccm
and 80 sccm. The cooling roll at 0° C. was provided at the back
surface of the substrate and the transparent plastic film was cooled.
Electric power of 7.8 W/cm
2 was supplied to the target, and a dynamic
rate was 23 nm.multidot.m/min. The transparent conductive film was used as
one panel plate and a touchpanel was manufactured as in the fourteenth
example.
Eigthteenth Example
The transparent conductive film manufactured as in the fourteenth example
was attached to a polycarbonate sheet having a thickness of 1.0 mm through
acrylic tackifier to provide a transparent conductive layered stack sheet.
The transparent conductive layered stack sheet was used as a fixed
electrode, and the transparent conductive film of the fifteenth example
was used as a movable electrode to manufacture a touchpanel as in the
fourteenth example.
Example 14A
A transparent conductive film was manufactured as in the fourteenth example
except that a heat treatment at 180° C. for one minute and a
process of reducing volatile component by a vacuum exposure for 10 minutes
were not performed. Further, with use of the transparent conductive film,
a touchpanel was manufactured as in the fourteenth example.
Example 14B
A touchpanel was manufactured as in the fourteenth example except that a
heat treatment was performed at 210° C. for one minute was
performed.
The measurement results of the above described fourteenth to eighteenth
examples as well as examples 14A and 14B are shown in Table 3, and output
shapes of the fourteenth to eighteenth examples are shown in FIGS. 21 to
25.
Referring to Table 3, the transparent conductive films and transparent
conductive sheets of the fourteenth to eighteenth examples provide
transparent conductive thin films of high hardness. Whitening was not
caused to the touchpanel with the transparent conductive film even after
100,000 sliding test with a load of 5.0N using a polyacetal pen (leading
edge: 0.8 mmR), and an On resistance was not deteriorated. In addition,
the input circle mark was properly recognized.
On the other hand, in the case of example 14A, because of its insufficient
hardness, when used for the touchpanel, the sliding portion was slightly
whitened after 100,000 sliding test with a load of 5.0N using a polyacetal
pen (leading edge: 0.8 mmR), and an ON resistance increased. In addition,
the recognition accuracy of the input circle mark at the sliding portion
was somewhat inferior.
The transparent conductive film of the example 14B was a fragile thin film
because of its extremely high hardness of the transparent conductive thin
film. Although whitening was not caused or an ON resistance did not
increase, after 100,000 sliding test with a load of 5.0N using a
polyacetal pen (leading edge: 0.8 mmR), recognition accuracy of the input
circle mark at the sliding portion was inferior. This is because cracks
were caused to the transparent conductive thin film due to the sliding
test.
TABLE 3
Hard- Test of endurance
to pen-sliding
ness
ON
of thin Light ray Surface Whitening
Initial resistance
film transmit- Haze resistance Adhesion at sliding
resistance after test
(GPa) tance (%) (%) (Ω/.quadrature.) (N/15 mm)
portion (kΩ) (k/Ω)
Example 14 0.51 88.3 0.8 250 1.5 None
2.0 2.0
Example 15 0.51 88.5 5.9 250 1.5 None
2.0 2.0
Example 16 0.51 87.3 5.9 250 1.5 None
2.0 2.0
Example 17 0.51 89.8 1.5 250 1.5 None
2.0 2.0
Example 18 0.51 88.1 1.7 250 1.5 None
2.0 2.0
Example 14A 0.34 88.5 1.2 250 1.5 Some
2.0 >1000
Example 14B 0.89 89.2 0.8 380 0.5 None
2.0 2.1
Note
There were 60 protrusions over the surface of the transparent conductive
thin film per 100 µm2 in each of the above examples each having an
diameter of 0.08 µm and height of 0.30 µm.
The transparent conductive thin film of the present invention has good
slidability and transparency because of its specific number (3-200/100
µm
2) of protrusions of a specific configuration (having a diameter
of 0.05-3.0 µm and a height of 0.005-2.00 µm) over the surface of
the transparent conductive thin film with the cured layer mainly including
a curable resin and the transparent conductive thin film successively
layered on the transparent plastic film base.
Since the volatile component of the film is at most 30 ppm, a transparent
conductive film of good quality can be formed. Thus, separation, cracks or
the like are not caused to a touchpanel for pen input using the
transparent conductive film even if the opposite transparent conductive
films are brought into contact by the pen pressure.
Further, the transparent conductive film is characterized in that the
hardness of the transparent conductive thin film is 0.4-0.8 Pa, so that
separation, cracks or the like are not caused to a touchpanel for pen
input using the transparent conductive film even if the opposite
transparent conductive films are brought into contact by the pen pressure.
The touchpanel for pen input of the present invention has good resistance
to pen input, e.g., separation, cracks or the like are not caused even if
the opposite transparent conductive films are brought into contact by the
pen pressure, and has excellent position detecting accuracy and display
quality. As such, it is well suited as a touchpanel for pen input.
Although the present invention has been described and illustrated in
detail, it is clearly understood that the same is by way of illustration
and example only and is not to be taken by way of limitation, the spirit
and scope of the present invention being limited only by the terms of the
appended claims.
* * * * *
United States Patent 6603085
