U.S. patent application number 13/030621 was filed with the patent office on 2011-06-23 for transparent conductive film, method for production thereof and touch panel therewith.
This patent application is currently assigned to NITTO DENKO CORPORATION. Invention is credited to Tomotake Nashiki, Hideo Sugawara.
Application Number | 20110147340 13/030621 |
Document ID | / |
Family ID | 39274619 |
Filed Date | 2011-06-23 |
United States Patent
Application |
20110147340 |
Kind Code |
A1 |
Nashiki; Tomotake ; et
al. |
June 23, 2011 |
TRANSPARENT CONDUCTIVE FILM, METHOD FOR PRODUCTION THEREOF AND
TOUCH PANEL THEREWITH
Abstract
A transparent conductive film includes: a transparent film
substrate; a transparent conductor layer provided on one or both
sides of the transparent film substrate; and at least one undercoat
layer interposed between the transparent film substrate and the
transparent conductor layer; wherein: the transparent conductor
layer is patterned; and a non-patterned portion not having the
transparent conductor layer has the at least one undercoat
layer.
Inventors: |
Nashiki; Tomotake; (Osaka,
JP) ; Sugawara; Hideo; (Osaka, JP) |
Assignee: |
NITTO DENKO CORPORATION
Osaka
JP
|
Family ID: |
39274619 |
Appl. No.: |
13/030621 |
Filed: |
February 18, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12015006 |
Jan 16, 2008 |
|
|
|
13030621 |
|
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|
Current U.S.
Class: |
216/13 |
Current CPC
Class: |
H01H 2219/012 20130101;
H01H 2229/016 20130101; Y10T 428/24802 20150115; G06F 3/04886
20130101; Y10T 428/24612 20150115; H01H 2201/028 20130101; H01H
2209/082 20130101; H01H 2239/006 20130101; G06F 3/044 20130101 |
Class at
Publication: |
216/13 |
International
Class: |
H05K 13/00 20060101
H05K013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 18, 2007 |
JP |
2007-009295 |
Aug 30, 2007 |
JP |
2007-224232 |
Claims
1. A method for producing a transparent conductive film comprising
a transparent film substrate; a transparent conductor layer
provided on one or both sides of the transparent film substrate;
and at least one undercoat layer interposed between the transparent
film substrate and the transparent conductor layer; wherein the
transparent conductor layer is patterned; and a non-patterned
portion not having the transparent conductor layer has the at least
one undercoat layer, said method comprising the steps of: forming
at least one undercoat layer on one or both sides of the
transparent film substrate, forming the transparent conductor layer
with sputtering on the at least one undercoat layer, patterning the
transparent conductor layer by etching with an acid, and
crystallizing the patterned transparent conductor layer by
annealing, after the step of patterning the transparent conductor
layer.
2. The method according to claim 1, wherein the first undercoat
layer from the transparent film substrate is formed with an organic
material.
3. The method according to claim 1, wherein at least two undercoat
layers are interposed, and further comprising the step of forming
the undercoat layer most distant from the transparent film
substrate with an inorganic material.
4. The method according to claim 3, wherein the undercoat layer
made of the inorganic material is a SiO.sub.2 film formed by
applying a silica sol.
5. The method according to claim 1, wherein there is a difference
of 0.1 or more between the refractive indices of the transparent
conductor layer and the undercoat layer.
Description
[0001] This application is a continuation of application Ser. No.
12/015,006 filed Jan. 16, 2008, which is hereby incorporated by
reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a transparent conductive
film that has transparency in the visible light range and includes
a film substrate and a transparent conductor layer provided on the
substrate with an undercoat layer interposed therebetween, and also
to a method for production thereof. The invention also relates to a
touch panel including the transparent conductive film.
[0004] The transparent conductive film of the present invention may
be used for transparent electrodes in touch panels and display
systems such as liquid crystal displays and electroluminescence
displays and also used for electromagnetic wave shielding or
prevention of static charge of transparent products. In particular,
the transparent conductive film of the present invention is
preferably used for touch panels. The transparent conductive film
of the invention is particularly suitable for use in capacitive
coupling type touch panels.
[0005] 2. Description of the Related Art
[0006] Touch panels can be classified according to the position
detecting method into an optical type, an ultrasonic type, a
capacitive type, a resistive film type, and so on. Resistive film
type touch panels are configured to include a transparent
conductive film and a transparent conductor layer-carrying glass
plate that are arranged opposite to each other with a spacer
interposed therebetween, in which an electric current is allowed to
flow through the transparent conductive film, while the voltage at
the transparent conductor-carrying glass plate is measured. On the
other hand, capacitive type touch panels are basically configured
to include a substrate and a transparent conductive layer provided
on the substrate and characterized by having no moving part.
Capacitive type touch panels have high durability and high
transmittance and thus are suitable for use in vehicle
applications.
[0007] For example, a transparent conductive film for the touch
panels is proposed that includes a transparent film substrate, and
a first undercoat layer, a second undercoat layer and a transparent
conductor layer formed in this order from the film substrate side
on one side of the transparent film substrate (see Patent
Literature 1: Japanese Patent Application Laid-Open (JP-A) No.
2002-326301).
SUMMARY OF THE INVENTION
[0008] In the transparent conductive film, the transparent
conductor layer may be patterned. When the transparent conductor
layer is patterned, however, the difference between the patterned
portion and the non-patterned portion can become clear so that a
display device produced therewith can have a poor appearance.
Particularly, the transparent conductor layer is placed on the
light-incident surface side in capacitive coupling type touch
panels. Therefore, it is desired to produce a display device with a
good appearance, even when the transparent conductor layer is
patterned.
[0009] It is an object of the present invention to provide a
transparent conductive film that has a patterned transparent
conductor layer and a good appearance and to provide a method for
production thereof. It is another object of the invention to
provide a touch panel including such a transparent conductive
film.
[0010] As a result of investigations for solving the problems, the
inventors of the present invention have found that the objects can
be achieved using the features described below, and finally
completed the invention.
[0011] Namely, the transparent conductive film of the present
invention is a transparent conductive film, comprising: a
transparent film substrate; a transparent conductor layer provided
on one or both sides of the transparent film substrate; and at
least one undercoat layer interposed between the transparent film
substrate and the transparent conductor layer; wherein: the
transparent conductor layer is patterned; and a non-patterned
portion not having the transparent conductor layer has the at least
one undercoat layer.
[0012] In the above, it is preferable that at least two undercoat
layers are interposed, and at least the undercoat layer most
distant from the transparent film substrate is patterned in the
same manner as the transparent conductor layer.
[0013] In the above, it is preferable that at least two undercoat
layers are interposed, and at least the undercoat layer most
distant from the transparent film substrate is made of an inorganic
material. It is preferable that the undercoat layer made of the
inorganic material is a SiO.sub.2 film.
[0014] In the above, it is preferable that the first undercoat
layer from the transparent film substrate is made of an organic
material.
[0015] In the above, it is preferable that there is a difference of
0.1 or more between the refractive indices of the transparent
conductor layer and the undercoat layer.
[0016] In the above, it is preferable that two undercoat layers are
interposed between the patterned transparent conductor layer and
the transparent film substrate, the first undercoat layer from the
transparent film substrate has a refractive index (n) of 1.5 to 1.7
and a thickness (d) of 100 nm to 220 nm, the second undercoat layer
from the transparent film substrate has a refractive index (n) of
1.4 to 1.5 and a thickness (d) of 20 nm to 80 nm, the transparent
conductor layer has a refractive index (n) of 1.9 to 2.1 and a
thickness (d) of 15 nm to 30 nm, and the total of the optical
thicknesses (n.times.d) of the respective layers is from 208 nm to
554 nm.
[0017] In the above, it is preferable that there is a difference
(.DELTA.nd) of 40 nm to 130 nm between the total of the optical
thicknesses of the patterned transparent conductor layer and the
two undercoat layers and the optical thickness of the undercoat
layer in the non-patterned portion.
[0018] Also, the transparent conductive film of the present
invention is a transparent conductive film, comprising: at least
two pieces of the above-mentioned transparent conductive film that
are laminated with a transparent pressure-sensitive adhesive layer
interposed therebetween such that the patterned transparent
conductor layer is placed on at least one side.
[0019] Also, the transparent conductive film of the present
invention is a transparent conductive film, comprising: the
above-mentioned transparent conductive film, and a transparent
substrate that is bonded to one side of the above-mentioned
transparent conductive film with a transparent pressure-sensitive
adhesive layer interposed therebetween such that the patterned
transparent conductor layer is placed on one side.
[0020] In the above, it is preferable that the transparent
conductive film is for use in a touch panel. It is preferable that
the touch panel is a capacitive coupling type touch panel.
[0021] Also, the method for producing a transparent conductive film
of the present invention is a method for producing the
above-mentioned transparent conductive film, comprising the steps
of: preparing a transparent conductive film comprising a
transparent film substrate and a transparent conductor layer formed
on one or both sides of the transparent film substrate with at
least one undercoat layer interposed therebetween; and patterning
the transparent conductor layer by etching with an acid.
[0022] In the above, it is preferable that at least two undercoat
layers are interposed, and the method further comprises the step of
etching at least the undercoat layer most distant from the
transparent film substrate with an alkali after the step of
patterning the transparent conductor layer by etching with an
acid.
[0023] In the above, it is preferable that the method further
comprises the step of crystallizing the patterned transparent
conductor layer by annealing, after the step of patterning the
transparent conductor layer.
[0024] Also, the touch panel of the present invention is a touch
panel, comprising the above-mentioned transparent conductive
film.
[0025] In conventional transparent conductive films, patterned
transparent conductor layers produce a clear difference in
reflectance between the patterned and non-patterned portions so
that the appearance can be degraded. In the transparent conductive
film of the present invention, the transparent conductor layer is
patterned, but the non-patterned portion has the undercoat layer so
that the difference in reflectance between the patterned and
non-patterned portions can be kept small. Thus, the defect caused
by patterned portions distinguishable from one another can be
avoided so that a good appearance can be provided. The formation of
the undercoat layer in the non-patterned portion prevents the
exposure of the film substrate so that oligomer generation can be
inhibited in the film substrate, which is favorable for the
appearance. The undercoat layer provided in the non-patterned
portion can insulate portions of the patterned transparent
conductor layer from one another, and the patterned transparent
conductor layer can widen the scope of application of the
transparent conductive film. The transparent conductive film
described above is suitable for use in touch panels and
particularly suitable for use in capacitive coupling type touch
panels.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a cross-sectional view showing a transparent
conductive film according to one embodiment of the present
invention;
[0027] FIG. 2 is a cross-sectional view showing a transparent
conductive film according to one embodiment of the present
invention;
[0028] FIG. 3 is a cross-sectional view showing a transparent
conductive film according to one embodiment of the present
invention;
[0029] FIG. 4 is a cross-sectional view showing a transparent
conductive film according to Comparative Example 1;
[0030] FIG. 5 is a cross-sectional view showing a transparent
conductive film according to one embodiment of the present
invention;
[0031] FIG. 6 is a cross-sectional view showing a transparent
conductive film according to one embodiment of the present
invention;
[0032] FIG. 7 is a cross-sectional view showing a transparent
conductive film according to one embodiment of the present
invention;
[0033] FIG. 8 is a cross-sectional view showing a transparent
conductive film according to one embodiment of the present
invention;
[0034] FIG. 9 is a cross-sectional view showing a transparent
conductive film according to one embodiment of the present
invention;
[0035] FIG. 10 is a cross-sectional view showing a transparent
conductive film according to one embodiment of the present
invention;
[0036] FIG. 11 is a cross-sectional view showing a transparent
conductive film according to one embodiment of the present
invention;
[0037] FIG. 12 is a cross-sectional view showing a transparent
conductive film according to one embodiment of the present
invention;
[0038] FIG. 13 is a top view showing an example of the pattern of
the transparent conductive film of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0039] Embodiments of the present invention are described below
with reference to the drawings. FIG. 1 is a cross-sectional view
showing an example of the transparent conductive film of the
invention. The transparent conductive film of FIG. 1 includes a
transparent film substrate 1 and a transparent conductor layer 3
provided on one side of the substrate 1 with an undercoat layer 2
interposed therebetween. The transparent conductor layer 3 is
patterned. In each drawing, patterning of the transparent conductor
layer 3 is indicated by the combination of a patterned portion a
having the transparent conductor layer 3 and a non-patterned
portion b not having the transparent conductor layer 3. The
non-patterned portion b has the undercoat layer 2. FIGS. 2 and 3
show cases where two undercoat layers (generically indicated by 2)
are provided. In FIG. 2 or 3, undercoat layers 21 and 22 are formed
in this order from the transparent film substrate 1 side. FIG. 2
shows a case where the non-patterned portion b has undercoat layers
21 and 22. In FIG. 3, an undercoat layer 22 most distant from the
transparent film substrate 1 is also patterned in the same manner
as the transparent conductor layer 3. In FIG. 3, the non-patterned
portion b has an undercoat layer 21. Specifically, where the
undercoat layer 2 has a two-layer structure, the non-patterned
portion b has at least the first undercoat layer 21 from the
transparent film substrate 1 side. While FIGS. 2 and 3 each
illustrate the case where the undercoat layers 2 has a two-layer
structure, the undercoat layer 2 may have a three- or more-layer
structure. When the undercoat layer 2 has a three- or more-layer
structure, the non-patterned portion b may have at least the first
undercoat layer 21 from the transparent film substrate 1 side. An
undercoat layer or layers upper than the first undercoat layer may
be patterned or not patterned. It is preferred that the undercoat
layer 2 should be composed of at least two layers, because in such
a case, the difference in reflectance between the patterned portion
a and the non-patterned portion b can be controlled to be small.
Particularly when the undercoat layer 2 is composed of at least two
layers, the undercoat layer most distant from the transparent film
substrate (the layer 22 when the undercoat layer 2 is composed of
two layers as shown in FIG. 3) is preferably patterned in the same
manner as the transparent conductor layer 3, in order that the
difference in reflectance between the patterned portion a and the
non-patterned portion b may be controlled to be small. FIG. 4 shows
a case where a patterned transparent conductor layer 3 is provided
on one side of a transparent film substrate 1 without the undercoat
layer 2 interposed therebetween.
[0040] FIG. 5 is also a cross-sectional view showing a further
example of the transparent conductive film of the invention. While
the structure shown in FIG. 1 is used for illustration in FIG. 5,
it will be understood that the structure shown in FIG. 2 or 3 may
also be used as an alternative in the case of FIG. 5. The
transparent conductive film of FIG. 5 includes a transparent film
substrate 1 and a patterned transparent conductor layer 3 provided
on both sides of the substrate 1 with an undercoat layer 2
interposed therebetween. The transparent conductive film of FIG. 5
has the patterned transparent conductor layer 3 on both sides.
Alternatively, however, the transparent conductor layer 3 may be
patterned only on one side. In the transparent conductive film of
FIG. 5, the patterned portion a and the non-patterned portion b in
the patterned transparent conductor layer 3 on one side are the
same as those on the other side. Alternatively, however, these may
be different between both sides, and both sides may be each
appropriately patterned in various shapes. This applies to the
cases of the other drawings.
[0041] FIGS. 6 to 9 each also show a further example of the
transparent conductive film of the present invention. The
transparent conductive film of each of FIGS. 6 to 9 includes two
pieces of the transparent conductive film shown in FIG. 1 or 5
laminated with a transparent pressure-sensitive adhesive layer 4
interposed therebetween. In each of FIGS. 6 to 9, the transparent
conductive films obtained by being laminated are laminated such
that the patterned transparent conductor layer 3 is placed on at
least one side. In FIGS. 6 and 7, two pieces of the transparent
conductive film shown in FIG. 1 are laminated with the transparent
pressure-sensitive adhesive layer 4 interposed therebetween. FIG. 6
shows a case where the transparent film substrate 1 of a piece of
the transparent conductive film shown in FIG. 1 is laminated on the
patterned transparent conductor layer 3 of another piece of the
transparent conductive film shown in FIG. 1 with the transparent
pressure-sensitive adhesive layer 4 interposed therebetween. FIG. 7
shows a case where the transparent film substrates 1 of two pieces
of the transparent conductive film shown in FIG. 1 are laminated on
each other with the transparent pressure-sensitive adhesive layer 4
interposed therebetween. In FIGS. 8 and 9, the transparent
conductive film shown in FIG. 1 is laminated on the transparent
conductive film shown in FIG. 5 with the transparent
pressure-sensitive adhesive layer 4 interposed therebetween. FIG. 8
shows a case where the patterned transparent conductor layer 3 of
the transparent conductive film shown in FIG. 1 is laminated on one
of the patterned transparent conductor layers 3 of the transparent
conductive film shown in FIG. 5 with the transparent
pressure-sensitive adhesive layer 4 interposed therebetween. FIG. 9
shows a case where the transparent film substrate 1 of the
transparent conductive film shown in FIG. 1 is laminated on one of
the patterned transparent conductor layers 3 of the transparent
conductive film shown in FIG. 5 with the transparent
pressure-sensitive adhesive layer 4 interposed therebetween. FIGS.
6 to 9 illustrate the case where the transparent conductive film
shown in FIG. 1 or 5 is used for the lamination of two pieces with
the transparent pressure-sensitive adhesive layer interposed
therebetween. Alternatively, however, three or more pieces may be
appropriately combined using the transparent conductive film shown
in FIG. 1 or 5 according to the embodiment of each of FIGS. 6 to 9.
While the structure of FIG. 1 is used in the case of each of FIGS.
6 to 9 for illustration, it will be understood that the structure
of FIG. 2 or 3 may be used instead in the case of each of FIGS. 6
to 9.
[0042] The transparent conductive film of the present invention may
be provided with the pressure-sensitive adhesive layer 4 when used.
The pressure-sensitive adhesive layer 4 may be laminated on one
side of the transparent conductive film in a similar manner to the
placement of the patterned transparent conductor layer 3. FIG. 10
shows a case where the transparent pressure-sensitive adhesive
layer 4 is laminated on the transparent film substrate 1 of the
transparent conductive film shown in FIG. 1. FIG. 11 shows a case
where the transparent pressure-sensitive adhesive layer 4 is
laminated on one of the patterned transparent conductor layers 3 of
the transparent conductive film shown in FIG. 5. In FIG. 10 or 11,
a separator S is provided on the pressure-sensitive adhesive layer
4. Even when two or more transparent conductive films are laminated
as shown in FIGS. 6 to 9, the pressure-sensitive adhesive layer 4
may also be laminated on one side of the transparent conductive
film in a similar manner to the placement of the patterned
transparent conductor layer 3.
[0043] A transparent substrate 5 may be further bonded to one side
of the transparent conductive film with a transparent
pressure-sensitive adhesive layer 4 interposed therebetween. The
transparent substrate 5 may be bonded to the transparent conductive
film in a similar manner to the placement of the patterned
transparent conductor layer 3 on one side. FIG. 12 shows another
transparent conductive film that is configured to include the
transparent conductive film of FIG. 1 and a transparent substrate 5
that is bonded to the transparent film substrate 1 of the
transparent conductive film of FIG. 1 (on the side where the
transparent conductor layer 3 is not provided) with a transparent
pressure-sensitive adhesive layer 4 interposed therebetween. The
transparent substrate 5 may comprise a single base film or a
laminate of two or more base films (which may be laminated with a
transparent pressure-sensitive adhesive layer interposed
therebetween). FIG. 12 also shows a case where a hard coat layer
(resin layer) 6 is provided on the outer surface of the transparent
substrate 5. The transparent conductive film of FIG. 1 is used for
illustration in FIG. 12. Alternatively, however, the transparent
conductive film of FIG. 2 or 3 may be used in the same structure.
The transparent conductive film configured as shown in each of
FIGS. 5 to 9 may also be used in the same structure.
[0044] There is no particular limitation to the film substrate 1,
and various types of plastic films having transparency may be used.
Examples of the material for the film substrate 1 include polyester
resins, acetate resins, polyethersulfone resins, polycarbonate
resins, polyamide resins, polyimide resins, polyolefin resins,
(meth)acrylic resins, polyvinyl chloride resins, polyvinylidene
chloride resins, polystyrene resins, polyvinyl alcohol resins,
polyarylate resins, and polyphenylene sulfide resins. In
particular, polyester resins, polycarbonate resins, and polyolefin
resins are preferred.
[0045] Examples thereof also include polymer films as disclosed in
JP-A No. 2001-343529 (WO01/37007) and a resin composition that
contains (A) a thermoplastic resin having a side chain of a
substituted and/or unsubstituted imide group and (B) a
thermoplastic resin having a side chain of substituted and/or
unsubstituted phenyl and nitrile groups. Specifically, a polymer
film of a resin composition containing an alternating copolymer
made of isobutylene and N-methylmaleimide, and an
acrylonitrile-styrene copolymer may be used.
[0046] The thickness of the film substrate 1 is preferably in the
range of 2 to 200 .mu.m, more preferably in the range of 2 to 100
.mu.m. If the thickness of the film substrate 1 is less than 2
.mu.m, the film substrate 1 can have insufficient mechanical
strength so that it can be difficult to use the film substrate 1 in
the form of a roll in the process of continuously forming the
undercoat layer 2 and the transparent conductor layer 3 in some
cases. If the thickness exceeds 200 .mu.m, it can be impossible to
improve the scratch resistance of the transparent conductor layer 3
or the tap properties thereof for touch panels in some cases.
[0047] The surface of the film substrate 1 may be previously
subject to sputtering, corona discharge treatment, flame treatment,
ultraviolet irradiation, electron beam irradiation, chemical
treatment, etching treatment such as oxidation, or undercoating
treatment such that the adhesion of the undercoat layer 2 formed
thereon to the film substrate 1 can be improved. If necessary, the
film substrate may also be subjected to dust removing or cleaning
by solvent cleaning, ultrasonic cleaning or the like, before the
undercoat layer 2 is formed.
[0048] According to the invention, having the undercoat layer 2
makes it possible to obtain a good appearance display device, even
when the transparent conductor layer 3 is patterned. From this
point of view, the undercoat layer 2 preferably has a refractive
index that is 0.1 or more different from the refractive index of
the transparent conductor layer 3. The difference between the
refractive indices of the transparent conductor layer 3 and the
undercoat layer is preferably from 0.1 to 0.9, more preferably from
0.1 to 0.6. The undercoat layer 2 generally has a refractive index
of 1.3 to 2.5, preferably of 1.38 to 2.3, more preferably of 1.4 to
2.3.
[0049] The undercoat layer 2 may be made of an inorganic material,
an organic material or a mixture of inorganic and organic
materials. Examples of the inorganic material include NaF (1.3),
Na.sub.3AlF.sub.6 (1.35), LiF (1.36), MgF.sub.2 (1.38), CaF.sub.2
(1.4), BaF.sub.2 (1.3), SiO.sub.2 (1.46), LaF.sub.3 (1.55),
CeF.sub.3 (1.63), and Al.sub.2O.sub.3 (1.63), wherein each number
inside the parentheses indicates the light refractive index of each
material. In particular, SiO.sub.2, MgF.sub.2, Al.sub.2O.sub.3 or
the like is preferably used, and SiO.sub.2 is particularly
preferred. Besides the above, a complex oxide may also be used that
comprises about 10 to about 40 parts by weight of cerium oxide and
0 to about 20 parts by weight of tin oxide based on indium
oxide.
[0050] Examples of the organic material include acrylic resins,
urethane resins, melamine resins, alkyd resins, siloxane polymers,
and organosilane condensates. At least one selected from the above
organic materials may be used. In particular, a thermosetting resin
comprising a mixture of a melamine resin, an alkyd resin and an
organosilane condensate is preferably used as the organic
material.
[0051] The undercoat layer 2 is placed between the transparent film
substrate 1 and the transparent conductor layer 3. The undercoat
layer 2 does not function as an electrical conductor layer.
Specifically, the undercoat layer 2 is formed as a dielectric layer
such that it can provide insulation between portions of the
patterned transparent conductor layer 3. Therefore, the undercoat
layer 2 generally has a surface resistance of 1.times.10.sup.6
.OMEGA./square or more, preferably of 1.times.10.sup.7
.OMEGA./square or more, more preferably of 1.times.10.sup.8
.OMEGA./square or more. The surface resistance of the undercoat
layer 2 has no specific upper limit. In general, measuring limit,
about 1.times.10.sup.13 .OMEGA./square may be an upper limit for
the surface resistance of the undercoat layer 2, but it may be
higher than 1.times.10.sup.13 .OMEGA./square.
[0052] The first undercoat layer from the transparent film
substrate 1 is preferably made of an organic material in terms of
forming the patterned transparent conductor layer 3 by etching.
Therefore, the undercoat layer 2 composed of a single layer is
preferably made of an organic material.
[0053] When the undercoat layer 2 is composed of at least two
layers, at least a layer that forms the undercoat layer 2 and is
most distant from the transparent film substrate 1 is preferably
made of an inorganic material in terms of forming the patterned
transparent conductor layer 3 by etching. When the undercoat layer
2 is composed of three or more layers, a layer or layers that are
above the second layer from the transparent film substrate 1 are
also preferably made of an inorganic material.
[0054] The undercoat layer made of an inorganic material may be
formed by a dry process such as vacuum deposition, sputtering, and
ion plating or a wet process (coating). The inorganic material for
forming the undercoat layer is preferably SiO.sub.2 as described
above. In a wet process, a silica sol or the like may be applied to
form a SiO.sub.2 film.
[0055] Under the foregoing, when two layers of the undercoat layers
2 are formed, it is preferred that the first undercoat layer 21
should be made of an organic material and that the second undercoat
layer 22 should be made of an inorganic material.
[0056] The thickness of the undercoat layer 2 is generally, but not
limited to, from about 1 to about 300 nm, preferably from 5 to 300
nm, in view of optical design and the effect of preventing oligomer
production from the film substrate 1. When two or more undercoat
layers 2 are formed, the thickness of each layer may be from about
5 to about 250 nm, preferably from 10 to 250 nm.
[0057] As described above, the transparent conductor layer 3
preferably has a refractive index that is 0.1 or more different
from the refractive index of the undercoat layer 2. The transparent
conductor layer 3 generally has a refractive index of about 1.95 to
about 2.05.
[0058] Examples of materials that may be used to form the
transparent conductor layer 3 include, but are not limited to,
oxides of at least one metal selected from the group consisting of
indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium,
magnesium, aluminum, gold, silver, copper, palladium, and tungsten.
Such metal oxides may be optionally doped with any metal atom
selected from the above group. For example, indium oxide doped with
tin oxide or tin oxide doped with antimony is preferably used.
[0059] The thickness of the transparent conductor layer 3 is
preferably, but not limited to, 10 nm or more, in terms of making
it in the form of a continuous coating with good electrical
conductivity and a surface resistance of 1.times.10.sup.3
.OMEGA./square or less. If it is too thick, its transparency can be
reduced. Thus, it preferably has a thickness of 15 to 35 nm, more
preferably within the range of 20 to 30 nm. If it has a thickness
of less than 15 nm, its surface electric resistance can be high,
and it can be difficult to make it in the form of a continuous
film. If it has a thickness of more than 35 nm, its transparency
can be reduced.
[0060] A production method of the transparent conductor layer 3 is
not particularly limited, and may be formed using any known
conventional method. Examples thereof include vacuum deposition,
sputtering, and ion plating. Any appropriate method may be used
depending on the desired thickness. After the transparent conductor
layer 3 is formed, it may be optionally crystallized by annealing
at a temperature in the range of 100 to 150.degree. C. For this
purpose, the film substrate 1 preferably has heat resistance to
100.degree. C. or higher, more preferably to 150.degree. C. or
higher. According to the present invention, the transparent
conductor layer 3 is patterned by etching. After the transparent
conductor layer 3 is crystallized, it can be difficult to etch it.
Therefore, it is preferred that the annealing of the transparent
conductor layer 3 should be performed after the transparent
conductor layer 3 is patterned. In a case where the undercoat layer
2 is also subjected to etching, the annealing of the transparent
conductor layer 3 is preferably performed after the etching of the
undercoat layer 2.
[0061] The transparent conductor layer 3 is patterned on the
undercoat layer 2. Any of various patterns may be formed depending
on applications for which the transparent conductive film can be
used. When the transparent conductor layer 3 is patterned, a
patterned portion and a non-patterned portion are formed. For
example, the patterned portion may have a stripe shape or any other
shape. FIG. 13 is a top view of an example of the transparent
conductive film of the present invention having the transparent
conductor layer 3 in a stripe shape. In this transparent conductive
film, a patterned portion a and a non-patterned portion b of the
transparent conductor layer 3 are formed in stripe shapes. In FIG.
13, the width of the patterned portion a is larger than that of the
non-patterned portion b, but this feature is optional.
[0062] The transparent conductive film of the invention may be
produced by any method without particular limitation, as long as an
undercoat layer and a transparent conductor layer each having the
above-described structure can be formed on one or both sides of a
transparent film substrate. According to a conventional technique,
for example, a transparent conductive film including a transparent
film substrate and a transparent conductor layer provided on one or
both sides of the film substrate with an undercoat layer interposed
between the film substrate and the conductor layer may be prepared,
and then the transparent conductor layer may be patterned by
etching, so that the transparent conductive film of the present
invention can be produced. In the etching process, the transparent
conductor layer may be covered with a patterning mask and then
etched with an etching solution.
[0063] Indium oxide doped with tin oxide or antimony-doped tin
oxide is preferably used to form the transparent conductor layer.
Therefore, an acid is preferably used for the etching solution.
Examples of the acid include inorganic acids such as hydrogen
chloride, hydrogen bromide, sulfuric acid, nitric acid, and
phosphoric acid; organic acids such as acetic acid; and any mixture
thereof and any aqueous solution thereof.
[0064] When at least two undercoat layers are provided, only the
transparent conductor layer may be patterned by etching, or
otherwise patterning of the transparent conductor layer by etching
with an acid may be followed by patterning of at least the
undercoat layer most distant from the transparent film substrate by
etching in the same manner as in the case of the transparent
conductor layer. Preferably, the undercoat layer or layers other
than the first undercoat layer from the transparent film substrate
may be patterned by etching in the same manner as in the case of
the transparent conductor layer.
[0065] In the process of etching the undercoat layer, the undercoat
layer may be covered with a mask for forming patterns in the same
manner as in the case of etching the transparent conductor layer
and then etched with an etching solution. As described above, an
inorganic material such as SiO.sub.2 is preferably used to form the
second undercoat layer or the undercoat layer(s) above the second
undercoat layer. Therefore, an alkali is preferably used for the
etching solution. Examples of the alkali include aqueous solutions
of sodium hydroxide, potassium hydroxide, ammonia, and
tetramethylammonium hydroxide; and any mixture thereof. The first
undercoat layer is preferably made of an organic material that
cannot be etched with acids or alkalis.
[0066] When the patterned transparent conductor layer is provided
through two undercoat layers to form the transparent conductive
film of the present invention, the refractive index (n) and
thickness (d) of each layer and the total of the optical
thicknesses (n.times.d) of the respective layers are preferably as
described below in the patterned portion, so that the patterned
portion and the non-patterned portion can be designed such that the
difference in reflectance between them can be small.
[0067] The first undercoat layer from the transparent film
substrate preferably has a refractive index (n) of 1.5 to 1.7, more
preferably of 1.5 to 1.65, sill more preferably of 1.5 to 1.6, and
preferably has a thickness (d) of 100 to 220 nm, more preferably of
120 to 215 nm, still more preferably of 130 to 210 nm.
[0068] The second undercoat layer from the transparent film
substrate preferably has a refractive index (n) of 1.4 to 1.5, more
preferably of 1.41 to 1.49, sill more preferably of 1.42 to 1.48,
and preferably has a thickness (d) of 20 to 80 nm, more preferably
of 20 to 70 nm, still more preferably of 20 to 60 nm.
[0069] The transparent conductor layer preferably has a refractive
index (n) of 1.9 to 2.1, more preferably of 1.9 to 2.05, sill more
preferably of 1.9 to 2.0, and preferably has a thickness (d) of 15
to 30 nm, more preferably of 15 to 28 nm, still more preferably of
15 to 25 nm.
[0070] The total of the optical thicknesses (n.times.d) of the
respective layers (the first and second undercoat layers and the
transparent conductor layer) is preferably from 208 to 554 nm, more
preferably from 230 to 500 nm, still more preferably from 250 to
450 nm.
[0071] The difference (.DELTA.nd) between the total of the optical
thicknesses in the patterned portion and the optical thickness of
the undercoat layer in the non-patterned portion is preferably from
40 to 130 nm. The difference (.DELTA.nd) between the optical
thicknesses is more preferably from 40 to 120 nm, still more
preferably from 40 to 110 nm.
[0072] As described above, at least two pieces of the transparent
conductive film of the present invention may be laminated with a
transparent pressure-sensitive adhesive layer 4 interposed
therebetween such that the patterned transparent conductor layer 3
is placed on at least one side. A transparent pressure-sensitive
adhesive layer 4 may also be laminated on the transparent
conductive film of the invention such that the patterned
transparent conductor layer 3 is placed on one side.
[0073] In a similar manner to the placement of the patterned
transparent conductor layer 3, a transparent substrate 5 may be
bonded to one side of the transparent conductive film of the
invention with a transparent pressure-sensitive adhesive layer 4
interposed therebetween. The transparent substrate 5 may be a
composite structure including at least two transparent base films
bonded to one another with a transparent pressure-sensitive
adhesive layer interposed therebetween. It is also possible to form
the patterned transparent conductor layer 3 in the transparent
conductive film with such a structure.
[0074] In general, the thickness of the transparent substrate 5 is
preferably from 90 to 300 .mu.m and more preferably controlled to
be from 100 to 250 .mu.m. When the transparent substrate 5 is
composed of a plurality of base films, the thickness of each base
film is preferably from 10 to 200 .mu.m, more preferably from 20 to
150 .mu.m, and may be controlled such that the total thickness of
the transparent substrate 5 including these base films and a
transparent pressure-sensitive adhesive layer(s) can fall within
the above range. Examples of the base film may include those
described above for the film substrate 1.
[0075] The transparent conductive film (e.g., the film substrate 1)
and the transparent substrate 5 may be bonded by a process
including the steps of forming the pressure-sensitive adhesive
layer 4 on the transparent substrate 5 side and bonding the film
substrate 1 thereto or by a process including the steps of forming
the pressure-sensitive adhesive layer 4 contrarily on the film
substrate 1 side and bonding the transparent substrate 5 thereto.
The latter process is more advantageous in view of productivity,
because it enables continuous production of the pressure-sensitive
adhesive layer 4 with the film substrate 1 in the form of a roll.
Alternatively, the transparent substrate 5 may be formed on the
film substrate 1 by sequentially laminating a plurality of base
films with the pressure-sensitive adhesive layers. The transparent
pressure-sensitive adhesive layer for use in laminating the base
films may be made of the same material as the transparent
pressure-sensitive adhesive layer 4 described below. The
transparent conductive films may also be laminated and bonded to
one another with a pressure-sensitive adhesive layer(s) 4, after
the surfaces to be bonded are appropriately selected.
[0076] Any transparent pressure-sensitive adhesive may be used for
the pressure-sensitive adhesive layer 4 without limitation. For
example, the pressure-sensitive adhesive may be appropriately
selected from adhesives based on polymers such as acrylic polymers,
silicone polymers, polyester, polyurethane, polyamide, polyvinyl
ether, vinyl acetate-vinyl chloride copolymers, modified
polyolefins, epoxy polymers, fluoropolymers, and rubbers such as
natural rubbers and synthetic rubbers. In particular, acrylic
pressure-sensitive adhesives are preferably used, because they have
good optical transparency and good weather or heat resistance and
exhibit suitable wettability and adhesion properties such as
cohesiveness and adhesiveness.
[0077] The anchoring strength can be improved using an appropriate
pressure-sensitive adhesive primer, depending on the type of the
pressure-sensitive adhesive as a material for forming the
pressure-sensitive adhesive layer 4. In the case of using such a
pressure-sensitive adhesive, therefore, a certain
pressure-sensitive adhesive primer is preferably used.
[0078] The pressure-sensitive adhesive primer may be of any type as
long as it can improve the anchoring strength of the
pressure-sensitive adhesive. For example, the pressure-sensitive
adhesive primer that may be used is a so-called coupling agent such
as a silane coupling agent having a hydrolyzable alkoxysilyl group
and a reactive functional group such as amino, vinyl, epoxy,
mercapto, and chloro in the same molecule; a titanate coupling
agent having an organic functional group and a titanium-containing
hydrolyzable hydrophilic group in the same molecule; and an
aluminate coupling agent having an organic functional group and an
aluminum-containing hydrolyzable hydrophilic group in the same
molecule; or a resin having an organic reactive group, such as an
epoxy resin, an isocyanate resin, a urethane resin, and an ester
urethane resin. In particular, a silane coupling agent-containing
layer is preferred, because it is easy to handle industrially.
[0079] The pressure-sensitive adhesive layer 4 may contain a
crosslinking agent depending on the base polymer. If necessary, the
pressure-sensitive adhesive layer 4 may also contain appropriate
additives such as natural or synthetic resins, glass fibers or
beads, or fillers comprising metal powder or any other inorganic
powder, pigments, colorants, and antioxidants. The
pressure-sensitive adhesive layer 4 may also contain transparent
fine particles so as to have light diffusing ability.
[0080] The transparent fine particles to be used may be one or more
types of appropriate conductive inorganic fine particles of silica,
calcium oxide, alumina, titania, zirconia, tin oxide, indium oxide,
cadmium oxide, antimony oxide, or the like with an average particle
size of 0.5 to 20 .mu.m or one or more types of appropriate
crosslinked or uncrosslinked organic fine particles of an
appropriate polymer such as poly(methyl methacrylate) and
polyurethane with an average particle size of 0.5 to 20 .mu.m.
[0081] The pressure-sensitive adhesive layer 4 is generally formed
using a pressure-sensitive adhesive solution with a solids content
of about 10 to 50% by weight, in which a base polymer or a
composition thereof is dissolved or dispersed in a solvent. An
organic solvent such as toluene and ethyl acetate, water, or any
other solvent may be appropriately selected depending on the type
of the pressure-sensitive adhesive and used as the above
solvent.
[0082] After the bonding of the transparent substrate 5, the
pressure-sensitive adhesive layer 4 has a cushion effect and thus
can function to improve the scratch resistance of the transparent
conductor layer formed on one side of the film substrate 1 or to
improve the tap properties thereof for touch panels, such as so
called pen input durability and surface pressure durability. In
terms of performing this function better, it is preferred that the
elastic modulus of the pressure-sensitive adhesive layer 4 is set
in the range of 1 to 100 N/cm.sup.2 and that its thickness is set
at 1 .mu.m or more, generally in the range of 5 to 100 .mu.m. If
the thickness is as described above, the effect can be sufficiently
produced, and the adhesion between the transparent substrate 5 and
the film substrate 1 can also be sufficient. If the thickness is
lower than the above range, the durability or adhesion cannot be
sufficiently ensured. If the thickness is higher than the above
range, outward appearances such as transparency can be degraded. In
other modes, the elastic modulus and thickness of the
pressure-sensitive adhesive layer 4 applied to the transparent
conductive film should also be the same as described above.
[0083] If the elastic modulus is less than 1 N/cm.sup.2, the
pressure-sensitive adhesive layer 4 can be inelastic so that the
pressure-sensitive adhesive layer can easily deform by pressing to
make the film substrate 1 irregular and further to make the
transparent conductor layer 3 irregular. If the elastic modulus is
less than 1 N/cm.sup.2, the pressure-sensitive adhesive can be
easily squeezed out of the cut section, and the effect of improving
the scratch resistance of the transparent conductor layer 3 or
improving the tap properties of the transparent conductor layer 3
for touch panels can be reduced. If the elastic modulus is more
than 100 N/cm.sup.2, the pressure-sensitive adhesive layer 4 can be
hard, and the cushion effect cannot be expected, so that the
scratch resistance of the transparent conductor layer 3 or the pen
input durability and surface pressure durability of the transparent
conductor layer 3 for touch panels tends to be difficult to be
improved.
[0084] If the thickness of the pressure-sensitive adhesive layer 4
is less than 1 .mu.m, the cushion effect also cannot be expected so
that the scratch resistance of the transparent conductor layer 3 or
the pen input durability and surface pressure durability of the
transparent conductor layer 3 for touch panels tends to be
difficult to be improved. If it is too thick, it can reduce the
transparency, or it can be difficult to obtain good results on the
formation of the pressure-sensitive adhesive layer 4, the bonding
workability of the transparent substrate 5, and the cost.
[0085] The transparent substrate 5 bonded through the
pressure-sensitive adhesive layer 4 as described above imparts good
mechanical strength to the film substrate 1 and contributes to not
only the pen input durability and the surface pressure durability
but also the prevention of curling.
[0086] The pressure-sensitive adhesive layer 4 may be transferred
using a separator S. In such a case, for example, the separator S
to be used may be a laminate of a polyester film of a
migration-preventing layer and/or a release layer, which is
provided on a polyester film side to be bonded to the
pressure-sensitive adhesive layer 4.
[0087] The total thickness of the separator S is preferably 30
.mu.m or more, more preferably in the range of 60 to 100 .mu.m.
This is to prevent deformation of the pressure-sensitive adhesive
layer 4 (dents) in a case where the pressure-sensitive adhesive
layer 4 is formed and then stored in the form of a roll, in which
the deformation (dents) can be expected to be caused by foreign
particles or the like intruding between portions of the rolled
layer.
[0088] The migration-preventing layer may be made of an appropriate
material for preventing migration of migrant components in the
polyester film, particularly for preventing migration of low
molecular weight oligomer components in the polyester. An inorganic
or organic material or a composite of inorganic and organic
materials may be used as a material for forming the
migration-preventing layer. The thickness of the
migration-preventing layer may be set in the range of 0.01 to 20
.mu.m as needed. The migration-preventing layer may be formed by
any method such as coating, spraying, spin coating, and in-line
coating. Vacuum deposition, sputtering, ion plating, spray thermal
decomposition, chemical plating, electroplating, or the like may
also be used.
[0089] The release layer may be made of an appropriate release
agent such as a silicone release agent, a long-chain alkyl release
agent, a fluorochemical release agent, and a molybdenum sulfide
release agent. The thickness of the release layer may be set as
appropriate in view of the release effect. In general, the
thickness is preferably 20 .mu.m or less, more preferably in the
range of 0.01 to 10 .mu.m, particularly preferably in the range of
0.1 to 5 .mu.m, in view of handleability such as flexibility. A
production method of the release layer is not particularly limited,
and may be formed in the same manner as in the case of the
migration-preventing layer.
[0090] An ionizing radiation-curable resin such as an acrylic
resin, a urethane resin, a melamine resin, and an epoxy resin or a
mixture of the above resin and aluminum oxide, silicon dioxide,
mica, or the like may be used in the coating, spraying, spin
coating, or in-line coating method. When the vacuum deposition,
sputtering, ion plating, spray thermal decomposition, chemical
plating, or electroplating method is used, a metal such as gold,
silver, platinum, palladium, copper, aluminum, nickel, chromium,
titanium, iron, cobalt, or tin or an oxide of an alloy thereof or
any other metal compounds such as metal iodides may be used.
[0091] If necessary, an antiglare or antireflection layer for
improving visibility or a hard coat layer (resin layer) 6 for
protecting the outer surface may be formed on the outer surface of
the transparent substrate 5 (on the side opposite to the
pressure-sensitive adhesive layer 4). For example, the hard coat
layer 6 is preferably made of a cured coating film of a curable
resin such as a melamine resin, a urethane resin, an alkyd resin,
an acrylic resin, and a silicone resin. The hard coat layer 6
preferably has a thickness of 0.1 to 30 .mu.m. If its thickness is
less than 0.1 .mu.m, its hardness can be inadequate. If its
thickness exceeds 30 .mu.m, the hard coat layer 6 can be cracked,
or curling can occur in the whole of the transparent substrate
5.
[0092] The transparent conductive film of the present invention may
be provided with an antiglare layer or an antireflection layer for
the purpose of increasing visibility. When the transparent
conductive film is used for a resistive film type touch panel, an
antiglare layer or an antireflection layer may be formed on the
outer surface of the transparent substrate 5 (on the side opposite
to the pressure-sensitive adhesive layer 4) similarly to the hard
coat layer 6. An antiglare layer or an antireflection layer may
also be formed on the hard coat layer 6. On the other hand, when
the transparent conductive film is used for a capacitive type touch
panel, an antiglare layer or an antireflection layer may be formed
on the transparent conductor layer 3.
[0093] For example, the material to be used to form the antiglare
layer may be, but not limited to, an ionizing radiation-curable
resin, a thermosetting resin, a thermoplastic resin, or the like.
The thickness of the antiglare layer is preferably from 0.1 to 30
.mu.m.
[0094] The antireflection layer may use titanium oxide, zirconium
oxide, silicon oxide, magnesium fluoride, or the like. In order to
produce a more significant antireflection function, a laminate of a
titanium oxide layer(s) and a silicon oxide layer(s) is preferably
used. Such a laminate is preferably a two-layer laminate comprising
a high-refractive-index titanium oxide layer (refractive index:
about 1.8), which is formed on the hard coat layer 6, and a
low-refractive-index silicon oxide layer (refractive index: about
1.45), which is formed on the titanium oxide layer. Also preferred
is a four-layer laminate which comprises the two-layer laminate and
a titanium oxide layer and a silicon oxide layer formed in this
order on the two-layer laminate. The antireflection layer of such a
two- or four-layer laminate can evenly reduce reflection over the
visible light wavelength range (380 to 780 nm).
[0095] For example, the transparent conductive film of the present
invention is suitable for use in optical type, ultrasonic type,
capacitive type, or resistive film type touch panels. In
particular, the transparent conductive film of the invention is
suitable for use in capacitive type touch panels. Also, the
transparent conductive film of the present invention can be
preferably used for flexible display devices of an electrophoretic
type, a twist ball type, a thermal rewritable type, an optical
recording liquid crystal type, a polymer-dispersed liquid crystal
type, a guest-host liquid crystal type, a toner display type, a
chromism type, an electrodeposition type, and the like.
EXAMPLES
[0096] The invention is more specifically described with some
examples below. It will be understood that the invention is not
limited to the examples below without departing from the gist of
the invention. In each example, the term "part or parts" means part
or parts by weight, unless otherwise stated. And in each example,
the term "%" means % by weight, unless otherwise stated.
(Refractive Index)
[0097] The refractive index of each layer was measured with a
measuring beam incident on the measurement surface of each object
in an Abbe refractometer manufactured by Atago Co., Ltd., according
the measurement method specified for the refractometer.
(Thickness of Each Layer)
[0098] The thickness of the layer with a thickness of at least 1
.mu.m, such as the film substrate, the transparent substrate, the
hard coat layer, and the pressure-sensitive adhesive layer, was
measured with a microgauge type thickness gauge manufactured by
Mitutoyo Corporation. The thickness of the layer whose thickness
was difficult to directly measure, such as the hard coat layer and
the pressure-sensitive adhesive layer, was calculated by
subtracting the thickness of the substrate from the measured total
thickness of the substrate and each layer formed thereon.
[0099] The thickness of the first undercoat layer, the second
undercoat layer or the ITO film was calculated using an
instantaneous multichannel photodetector system MCPD-2000 (trade
name) manufactured by Otsuka Electronics Co., Ltd., based on the
waveform data of the resulting interference spectrum.
(Surface Resistance of Undercoat Layer)
[0100] According to JIS K 6911 (1995), the electric surface
resistance (.OMEGA./square) of the undercoat layer was measured by
a double ring method using a surface high resistance meter
manufactured by Mitsubishi Chemical Co., Ltd.
Example 1
(Formation of Undercoat Layer)
[0101] A 185 nm-thick first undercoat layer was formed from a
thermosetting resin (light refractive index n of 1.54) on one side
of a film substrate composed of a 25 .mu.m-thick polyethylene
terephthalate film (hereinafter referred to as "PET film"). The
thermosetting resin was composed of a melamine resin, an alkyd
resin and an organosilane condensate (2:2:1 in weight ratio). A
silica sol (Colcoat P manufactured by Colcoat Co., Ltd.) was then
diluted with ethanol to a solids content concentration of 2%. The
diluted silica sol was applied to the first undercoat layer by a
silica coating method and then dried and cured at 150.degree. C.
for 2 minutes to form a 33 nm-thick second undercoat layer (a
SiO.sub.2 film with a light refractive index of 1.46). Both of the
first and second undercoat layers formed had a surface resistance
of 1.times.10.sup.12 .OMEGA./square or more.
(Formation of Transparent Conductor Layer)
[0102] A 22 nm-thick ITO film (with a light refractive index of
2.00) of an indium-tin complex oxide was formed on the second
undercoat layer by a reactive sputtering method using a sintered
material composed of 97% indium oxide and 3% tin oxide in a 0.4 Pa
atmosphere composed of 98% by volume of argon gas and 2% by volume
of oxygen gas. And so a transparent conductive film was
obtained.
(Formation of Hard Coat Layer)
[0103] A toluene solution as a material for forming a hard coat
layer was prepared by adding 5 parts of a photopolymerization
initiator of hydroxycyclohexyl phenyl ketone (Irgacure 184,
manufactured by Ciba Specialty Chemicals Inc.) to 100 parts of an
acrylic urethane resin (Unidic 17-806, manufactured by Dainippon
Ink and Chemicals, Incorporated) and diluting the mixture with
toluene to a concentration of 30%.
[0104] The hard coat layer-forming material was applied to one side
of a transparent substrate of a 125 .mu.m-thick PET film and dried
at 100.degree. C. for 3 minutes. The coating was then immediately
irradiated with ultraviolet light from two ozone-type high-pressure
mercury lamps (each 80 W/cm.sup.2 in energy density, 15 cm focused
radiation) to form a 5 .mu.m-thick hard coat layer.
(Preparation of Transparent Laminated Conductive Film)
[0105] Subsequently, an about 20 .mu.m-thick transparent acrylic
pressure-sensitive adhesive layer with an elastic modulus of 10
N/cm.sup.2 was formed on the other side of the transparent
substrate opposite to the hard coat layer-receiving side. The
pressure-sensitive adhesive layer was formed using a composition
prepared by adding one part of an isocyanate crosslinking agent to
100 parts of an acrylic copolymer of butyl acrylate, acrylic acid
and vinyl acetate (100:2:5 in weight ratio). The transparent
conductive film (on the side where the transparent conductor layer
is not provided) was bonded to the pressure-sensitive adhesive
layer side so that a transparent laminated conductive film was
obtained.
(Patterning of ITO Film by Etching)
[0106] A photoresist having a stripe pattern was applied to the
transparent conductor layer of the transparent laminated conductive
film and then dried and cured. Thereafter, the ITO film was etched
by immersing it in a 5% hydrochloric acid (aqueous hydrogen
chloride solution) at 25.degree. C. for 1 minute.
(Patterning of Second Undercoat Layer by Etching)
[0107] After the ITO film was etched, the second undercoat layer
was etched by immersing it in an aqueous 2% sodium hydroxide
solution at 45.degree. C. for 3 minutes, while the photoresist
remained laminated. Thereafter, the photoresist was removed.
(Crystallization of Transparent Conductor Layer)
[0108] After the second undercoat layer was etched, the ITO film
was crystallized by heating it at 140.degree. C. for 90
minutes.
Example 2
[0109] A transparent laminated conductive film with a patterned ITO
film was prepared using the process of Example 1, except that the
patterning of the second undercoat layer by etching was not
performed.
Example 3
[0110] A transparent laminated conductive film with a patterned ITO
film was prepared using the process of Example 1, except that the
thickness of the first undercoat layer was changed to 35 nm and
that the second undercoat layer was not formed.
Example 4
[0111] A transparent laminated conductive film with a patterned ITO
film was prepared using the process of Example 1, except that the
thickness of the first undercoat layer was changed to 150 nm.
Example 5
[0112] A transparent laminated conductive film with a patterned ITO
film was prepared using the process of Example 1, except that the
thickness of the first undercoat layer was changed to 150 nm and
that the patterning of the second undercoat layer by etching was
not performed.
[0113] In each of Examples 2 to 5, both of the first and second
undercoat layers formed had a surface resistance of
1.times.10.sup.12 .OMEGA./square or more.
Comparative Example 1
[0114] A transparent laminated conductive film with a patterned ITO
film was prepared using the process of Example 1, except that
neither the first nor second undercoat layer was formed.
Comparative Example 2
[0115] A transparent laminated conductive film with a patterned ITO
film (transparent surface conductor layer) was prepared using the
process of Example 1, except that a 33 nm-thick ITO film was formed
in place of the first undercoat layer, the thickness of the second
undercoat layer was changed to 60 nm, and the patterning of the
second undercoat layer by etching was not performed. The first
undercoat layer (ITO film) formed had a surface resistance of
2.times.10.sup.2 .OMEGA./square, and the second undercoat layer
formed had a surface resistance of 4.times.10.sup.2
.OMEGA./square.
[0116] The transparent laminated conductive films (samples) of the
examples and the comparative examples were evaluated as described
below. The results are shown in Tables 1 and 2.
(Surface Resistance of ITO Film)
[0117] The surface electric resistance (.OMEGA./square) of the ITO
film was measured using a two-terminal method.
(Resistance Value Between Patterned ITO Film Portions)
[0118] The electric resistance (.OMEGA.) between portions of the
patterned ITO film, which were each independently existing, was
measured with a tester, and whether they were insulated from one
another or not was evaluated. A resistance measurement of
1.times.10.sup.6.OMEGA. or more was evaluated as insulating. The
tester used was a digital tester CDM-2000D manufactured by
Custom.
(Light Transmittance)
[0119] The visible light transmittance was measured at a light
wavelength of 550 nm using a spectroscopic analyzer UV-240
manufactured by Shimadzu Corporation.
(Average Reflectance at 450 to 650 nm and Reflection Y Value)
[0120] A reflection spectrum was measured at a reflection incidence
angle of 10.degree. using a spectrophotometer U4100 manufactured by
Hitachi Ltd. in an integrating sphere measurement mode, and the
average reflectance and Y value in the range of 450 to 650 nm were
calculated. A light blocking layer was formed using a black color
spray on the back side (hard coat layer side) of the transparent
laminated conductive film (sample), and the measurement was
performed in a state where almost no light was reflected or came in
from the back side of the sample. For the calculation of the
reflected colors, the standard light D.sub.65 according to JIS Z
8720 was used when the measurement was performed under the 2-degree
visual field conditions. The measurement of the average reflectance
and Y value was performed on the patterned portion (ITO film) and
the non-patterned portion (etched portion), respectively. The
difference in reflectance between the patterned and non-patterned
portions (.DELTA.(reflectance)) and the difference in Y value
between them (.DELTA.(Y value)) are shown together in Table 2.
(Evaluation of Appearance)
[0121] The sample was placed on a black board such that the
transparent conductor layer side faced upward, and whether the
patterned and non-patterned portions were distinguishable from each
other or not was visually evaluated according to the criteria
below. [0122] .circle-w/dot.: The patterned portion is difficult to
distinguish from the non-patterned portion; [0123] .largecircle.:
The patterned portion is slightly distinguishable from the
non-patterned portion; and [0124] .times.: The patterned portion is
clearly distinguishable from the non-patterned portion.
TABLE-US-00001 [0124] TABLE 1 Composition of Transparent Conductive
Optical Thickness (nm) of Transparent Resistance Layer and AC Layer
(thickness: nm) Conductive Layer and AC Layer Surface between
Visible Light Patterned Non-Patterned Patterned Non-Patterned
Difference Resistance Portions with Transmittance Portion Portion
Portion Portion (.DELTA.nd) (.OMEGA./square) Pattern (.OMEGA.) (%)
Example 1 ITO (22 nm)/ First AC (185 nm) 377 285 92 300 >1
.times. 10.sup.12 90.5 Second AC (33 nm)/ First AC (185 nm) Example
2 ITO (22 nm)/ Second AC (33 nm)/ 377 333 44 300 >1 .times.
10.sup.12 89.5 Second AC (33 nm)/ First AC (185 nm) First AC (185
nm) Example 3 ITO(22 nm)/ First AC (35 nm) 98 54 44 300 >1
.times. 10.sup.12 89.0 First AC (35 nm) Example 4 ITO (22 nm)/
First AC (150 nm) 323 231 92 300 >1 .times. 10.sup.12 89.0
Second AC (33 nm)/ First AC (150 nm) Example 5 ITO (22 nm)/ Second
AC (33 nm)/ 323 279 44 300 >1 .times. 10.sup.12 89.0 Second AC
(33 nm)/ First AC (150 nm) First AC (150 nm) Comparative ITO(22 nm)
None 44 -- -- 300 >1 .times. 10.sup.12 87.0 Example 1
Comparative ITO (22 nm)/ Second AC (60 nm)/ 192 148 44 150 .sup. 1
.times. 10.sup.3 92.0 Example 2 Second AC (60 nm)/ First AC (30 nm)
ITO (30 nm) In Table 1, AC (layer) represents "undercoat
layer."
TABLE-US-00002 TABLE 2 Average Reflectance (%) at 450-650 nm Y
Value Patterned Non-Patterned Patterned Non-Patterned
.DELTA.(Reflectance) Appearance Portion Portion Portion Portion (%)
.DELTA.(Y value) Evaluation Example 1 6.9 7.1 6.8 7.3 0.6 0.5
.circle-w/dot. Example 2 6.9 5.8 6.8 6.2 1.0 0.6 .circle-w/dot.
Example 3 7.6 5.9 7.4 5.9 1.7 1.5 .largecircle. Example 4 8.2 6.1
8.3 6.4 2.1 1.8 .largecircle. Example 5 8.2 6.2 8.3 6.1 2.0 2.1
.largecircle. Comparative 10.2 7.2 10.0 7.6 3.2 2.5 X Example 1
Comparative 3.5 7.9 2.9 8.2 4.4 5.3 X Example 2
[0125] It is apparent from Tables 1 and 2 that the transparent
conductive films according to the invention each have a good
appearance, even though they each have a patterned transparent
conductor layer.
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