U.S. patent application number 13/892651 was filed with the patent office on 2013-09-26 for transparent laminate film and method for producing same.
This patent application is currently assigned to TOKAI RUBBER INDUSTRIES, LTD.. The applicant listed for this patent is TOKAI RUBBER INDUSTRIES, LTD.. Invention is credited to Hiroki INAGAKI, Masataka INUDUKA, Tetsuji NARASAKI, Taiji NISHITANI, Tetsuya TAKEUCHI.
Application Number | 20130248091 13/892651 |
Document ID | / |
Family ID | 43627861 |
Filed Date | 2013-09-26 |
United States Patent
Application |
20130248091 |
Kind Code |
A1 |
INUDUKA; Masataka ; et
al. |
September 26, 2013 |
TRANSPARENT LAMINATE FILM AND METHOD FOR PRODUCING SAME
Abstract
A transparent laminate film which has visible light
transmittance, sunlight blocking properties, radio wave
transmittance and good appearance is provided. A transparent
laminate film includes a laminate structure formed on at least one
side of a transparent polymer film, in which a metal oxide layer
and a metal layer are laminated, the metal oxide layer containing
an organic component, wherein grooves having a width of 30 .mu.m or
less are formed in the laminate structure, and an overall surface
resistance is 150.OMEGA./.quadrature. or more. Preferably, the
grooves are numerous cracks, or are formed by laser processing.
Further, preferably, the transparent polymer film has an easy
adhesion layer formed on at least one side thereof, and the
laminate structure is formed on top of the easy adhesion layer.
Furthermore, preferably, the metal oxide layer containing the
organic component is formed by a sol-gel method using optical
energy during sol-gel curing.
Inventors: |
INUDUKA; Masataka;
(Aichi-ken, JP) ; TAKEUCHI; Tetsuya; (Aichi-ken,
JP) ; INAGAKI; Hiroki; (Aichi-ken, JP) ;
NARASAKI; Tetsuji; (Aichi-ken, JP) ; NISHITANI;
Taiji; (Aichi-ken, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOKAI RUBBER INDUSTRIES, LTD. |
Aichi-ken |
|
JP |
|
|
Assignee: |
TOKAI RUBBER INDUSTRIES,
LTD.
Aichi-ken
JP
|
Family ID: |
43627861 |
Appl. No.: |
13/892651 |
Filed: |
May 13, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13308967 |
Dec 1, 2011 |
8455086 |
|
|
13892651 |
|
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PCT/JP2010/064179 |
Aug 23, 2010 |
|
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13308967 |
|
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Current U.S.
Class: |
156/209 |
Current CPC
Class: |
Y10T 428/24479 20150115;
Y10T 428/2457 20150115; B32B 17/064 20130101; Y10T 428/24612
20150115; B32B 3/30 20130101; B32B 7/12 20130101; Y10T 156/1082
20150115; G02B 5/22 20130101; Y10T 156/1023 20150115; G02B 5/26
20130101 |
Class at
Publication: |
156/209 |
International
Class: |
B32B 3/30 20060101
B32B003/30 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 26, 2009 |
JP |
2012-195020 |
Sep 16, 2009 |
JP |
2009-214667 |
Claims
1. A method for producing a transparent laminate film, comprising:
a lamination process forming, on at least one side of a transparent
polymer film, a laminate structure in which a metal oxide layer and
a metal layer are laminated, the metal oxide layer containing an
organic component; and a groove formation process forming grooves
having a width of 30 .mu.m or less in a formed laminate structure
so that an overall surface resistance is 150.OMEGA./.quadrature. or
more.
2. The method for producing a transparent laminate film according
to claim 1, wherein formation of the grooves is performed by
causing the organic component in the metal oxide layer containing
the organic component to react to cause cracks to form due to a
stress generated in the laminate structure during the reaction.
3. The method for producing a transparent laminate film according
to claim 1, wherein the organic component is a remaining component
of a starting material of a sol-gel method, and the formation of
the grooves comprises a step applying energy to the laminate
structure from a surface thereof in an atmosphere containing one
kind or two or more kinds of materials selected from oxygen, ozone,
and water.
4. The method for producing a transparent laminate film according
to claim 1, wherein the formation of the grooves is performed by
subjecting a surface of the laminate structure to laser
processing.
5. A method for producing a transparent laminate film, comprising:
a lamination process forming, on at least one side of a transparent
polymer film, a laminate structure in which a metal oxide layer and
a metal layer are laminated, the metal oxide layer containing an
organic component; and a groove formation process forming grooves
having a width of 30 .mu.m or less in a formed laminate structure
so that an overall surface resistance is 150.OMEGA./.quadrature. or
more, wherein the formation of the grooves is performed by
stretching of the transparent laminate film.
6. The method for producing a transparent laminate film according
to claim 5, wherein the stretching is a biaxial stretching.
Description
CLAIM FOR PRIORITY
[0001] This application is a divisional of U.S. application Ser.
No. 13/308,967, which is a continuation of PCT/JP2010/064179 filed
Aug. 23, 2010, and claims the priority benefit of Japanese
Applications No. 2009-195020, filed Aug. 26, 2009, and No.
2009-214667, filed Sep. 16, 2009, the contents of each of which are
expressly incorporated by reference in their entireties.
TECHNICAL FIELD
[0002] The present invention relates to a transparent laminate film
and a method for producing the same. More specifically, the present
invention relates to a transparent laminate film that can be
suitably used for heat ray cutting and a method for producing the
same.
TECHNICAL BACKGROUND
[0003] Conventionally, as a solar radiation shielding film, a heat
ray cut film is known. For example, in Patent Document 1, an
optical interference film formed by simultaneously extruding a
plurality of polymer layers having different refractive indices is
described.
[0004] In recent years, a transparent laminate film of a multilayer
film type is also proposed in which metal oxide layers and metal
layers are alternately laminated on one side of a transparent
polymer film. For example, in Patent Document 2, a transparent
laminate film is disclosed in which seven layers of titanium oxide
layers and silver layers are alternately laminated on one side of a
PET film, the titanium oxide layers being formed by using a sol-gel
method, and the silver layers being formed by using a sputtering
method. In the Patent Document 2, it is described that the
transparent laminate film is applicable to heat ray cutting.
[0005] Further, for example, in Patent Document 3, a technology is
disclosed in which, in a heat ray reflecting glass formed by
laminating a film having a high heat ray reflectance on a glass
substrate, the film has a surface resistivity of
500.OMEGA./.quadrature. or less, a dividing groove is formed on the
film, and a solar radiation transmittance is 50% or less. In the
Patent Document 3, it is described that, although a thermal
insulation film allows radio waves to pass through at a groove
width of about 50 .mu.m, when the groove width is too small,
because an electrical current jumps over a gap of the groove by a
displacement current, a thermal insulation film becomes an
electrically continuous body.
RELATED ART
Patent Documents
[0006] Patent Document 1: Japanese Patent Laid-Open Publication No.
H 4-313704 [0007] Patent Document 2: Japanese Patent Laid-Open
Publication No. 2005-353656 [0008] Patent Document 3: Japanese
Examined Patent Application Publication No. H 8-28592
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0009] However, the above described conventional technologies have
left room for improvement with respect to the following points.
[0010] For example, in order to reduce a rise in temperature in a
building, a house, or an automobile, a heat ray cut film may be
applied to a window glass. In this case, the heat ray cut film is
required to have such functional capabilities as visible light
transparency and solar radiation shielding capability. Further, in
a building, a house, and the like, in order to use a mobile phone,
a television, and the like, radio wave transparency at a high
frequency of several hundred MHz or more is required. In recent
years, ETC systems are in widespread use. When a heat ray cut film
is applied to a window glass of an automobile, radio wave
transparency is required so as to not hinder radio wave reception
of an in-vehicle ETC equipment.
[0011] However, the film of the Patent Document 1 is composed of a
plurality of polymer layers and does not include any metal layer.
Therefore, there is a problem that, although the film has radio
wave transparency, the film does not have sufficient solar
radiation shielding capability. In addition, when this film is
applied to a curved glass such as a windshield of an automobile,
the polymer layers may be partially distorted, causing film
thickness to change and color unevenness to occur, which may impair
appearance.
[0012] Further, the film of the Patent Document 2 has a laminate
structure in which metal oxide layers and metal layers are
laminated. Therefore, although the film has visible light
transparency and solar radiation shielding capability, because the
metal layers are continuous, the film has poor radio wave
transparency.
[0013] Further, in the technology of the Patent Document 3, the
dividing groove formed on the film has a wide width of 50 .mu.m or
more. Therefore, although the film allows radio waves to
efficiently pass through, the dividing groove is noticeable so that
the film has a poor appearance.
[0014] The preset invention is devised in view of the above
described problems. A problem to be solved by the present invention
is to provide a transparent laminate film that has a combination of
visible light transparency, solar radiation shielding capability,
radio wave transparency, and a good appearance.
Means for Solving the Problems
[0015] To solve the above described problems, a transparent
laminate film according to the present invention includes a
laminate structure formed on at least one side of a transparent
polymer film, in which a metal oxide layer and a metal layer are
laminated, the metal oxide layer containing an organic component.
Grooves having a width of 30 .mu.m or less are formed in the
laminate structure, and the transparent laminate film has an
overall surface resistance of 150.OMEGA./.quadrature. or more.
[0016] Here, it is desirable that the grooves be numerous
cracks.
[0017] Or, it is desirable that the grooves be formed by laser
processing.
[0018] In the transparent laminate film, it is desirable that the
transparent polymer film have an easy adhesion layer formed on at
least one side thereof, and the laminate structure be formed on top
of the easy adhesion layer.
[0019] Further, in the above transparent laminate film, it is
desirable that the metal oxide layer containing the organic
component be formed by a sol-gel method using optical energy during
sol-gel curing.
[0020] Further, it is desirable that a barrier layer composed
mainly of metal oxide be formed on at least one side of the metal
layer.
[0021] Further, it is desirable that the metal oxide layer be a
titanium oxide layer.
[0022] Further, it is desirable that the metal layer be a silver
layer or a silver alloy layer.
[0023] Further, it is desirable that the barrier layer be composed
mainly of titanium oxide.
[0024] Further, it is desirable that the barrier layer be a layer
formed by post-oxidizing a metal Ti layer or a layer formed by
post-oxidizing a partially oxidized titanium oxide layer.
[0025] Further, it is desirable that the transparent laminate film
have a visible light transmittance of 60% or more.
[0026] Further, it is desirable that the transparent laminate film
be used for transmission of radio wave of a frequency of 100 MHz or
more.
[0027] A method for producing a transparent laminate film according
to the present invention includes a lamination process forming, on
at least one side of a transparent polymer film, a laminate
structure in which a metal oxide layer and a metal layer are
laminated, the metal oxide layer containing an organic component;
and a groove formation process forming grooves having a width of 30
.mu.m or less in a formed laminate structure so that an overall
surface resistance of the transparent laminate film is
150.OMEGA./.quadrature. or more.
[0028] Here, it is desirable that formation of the grooves be
performed by causing the organic component in the metal oxide layer
containing the organic component to react, which causes cracks to
form due to a stress that occurs in the laminate structure during
the reaction.
[0029] Further, it is desirable that the organic component be a
remaining component of a starting material of a sol-gel method, and
the formation of the grooves include a step applying energy to the
laminate structure from a surface thereof in an atmosphere
containing one kind or two or more kinds of materials selected from
oxygen, ozone, and water.
[0030] Further, it is desirable that the formation of the grooves
be performed by subjecting the surface of the laminate structure to
laser processing.
[0031] Further, it is desirable that the formation of the grooves
be performed by stretching the transparent laminate film. In this
case, it is desirable that the stretching be a biaxial
stretching.
[0032] Another method for producing a transparent laminate film
according to the present invention includes preparing a transparent
polymer film having an easy adhesion layer formed on at least one
side thereof; forming a laminate structure by laminating a metal
oxide layer and a metal layer on top of the easy adhesion layer on
at least one side, the metal oxide layer containing an organic
component; and forming numerous cracks having a width of 30 .mu.m
or less in the laminate structure so that an overall surface
resistance of the transparent laminate film is
150.OMEGA./.quadrature. or more.
Effect of the Invention
[0033] The transparent laminate film according to the present
invention includes a laminate structure in which a metal oxide
layer and a metal layer are laminated, the metal oxide layer
containing an organic component. Therefore, the transparent
laminate film has good visible light transparency and solar
radiation shielding capability. Further, for the transparent
laminate film according to the present invention, groves having a
width of 30 .mu.m or less are formed in the laminate structure, and
the overall surface resistance is 150.OMEGA./.quadrature. or more.
That is, the metal layers in the laminate structures are broken by
the grooves having a width of 30 .mu.m or less so that the overall
surface resistance of the transparent laminate film is
150.OMEGA./.quadrature. or more. Therefore, in addition to a
practical radio wave transparency, the transparent laminate film
also has a good appearance as the grooves are hardly visible.
[0034] Therefore, the transparent laminate film according to the
present invention, which has a combination of visible light
transparency, solar radiation shielding capability, radio wave
transparency, and a good appearance, is useful as a film for
applying to a window glass of an architectural structure such as a
building, a house, and the like, a window glass of a vehicle such
as an automobile, and the like.
[0035] Here, in the case where the grooves are numerous cracks,
directionality in the surface resistance is unlikely to appear so
that the transparent laminate film has a superior uniformity in the
surface resistance. Further, cracks can be introduced into the
laminate structure in a relatively short time. Therefore, the
transparent laminate film has a superior mass productivity.
[0036] Further, in the case where the grooves are formed by laser
processing, the grooves can be formed in any form such as
lattice-like, strip-like, slit-like, and the like.
[0037] In the transparent laminate film, in the case where the
laminate structure is formed on top of an easy adhesion layer of
the transparent polymer film, the continuity of the metal layer can
be broken by cracks formed during the formation of the laminate
structure.
[0038] In the transparent laminate film, in the case where the
metal oxide layer containing the organic component is formed by a
sol-gel method using optical energy during sol-gel curing, a
starting material (such as a metal alkoxide and the like) of the
sol-gel method is likely to remain in the metal oxide layer as an
organic component. Therefore, by causing this organic component to
react so as to cause cracks to form by a stress generated in the
laminate structure during the reaction, grooves are easily
formed.
[0039] Further, in the case where a barrier layer composed mainly
of a metal oxide is formed on at least one side of the metal layer,
diffusion of metal elements constituting each metal layer due to
solar radiation can be inhibited. Therefore, the visible light
transparency, solar radiation shielding capability, radio wave
transparency, and good appearance are likely to be maintained for a
long period of time, which can contribute to improved durability
and reliability.
[0040] Further, in the case where the metal oxide layer is a
titanium oxide layer, a relatively high refractive index is likely
to be obtained. Therefore, visible light transparency is likely to
be improved.
[0041] Further, the case where the metal layer is a silver layer or
a silver alloy layer provides a good balance between visible light
transparency, solar radiation shielding capability, and radio wave
transparency, specified in the present invention.
[0042] Further, in the case where the barrier layer is composed
mainly of a titanium oxide, diffusion of the elements constituting
the metal layer such as silver and the like due to solar radiation
and heat is likely to be inhibited.
[0043] Further, in the case where the barrier layer is a layer
formed by post-oxidizing a metal Ti layer or a layer formed by
post-oxidizing a partially oxidized titanium oxide layer, absorbed
water and oxygen contained in the laminate structure are consumed
during post-oxidation. Therefore, even when exposed to sunlight,
shape change of the metal oxide layer containing the organic
component is inhibited, peeling of the laminate structure is
unlikely to occur, and durability against solar radiation is likely
improved.
[0044] Further, in the case where the visible light transmittance
is 60% or more, the transparent laminate film is useful as a film
for applying to a window glass of an architectural structure such
as a building and a house, a window glass of a vehicle such as an
automobile, and the like.
[0045] The method for producing a transparent laminate film
according to the present invention includes a lamination process
forming, on at least one side of a transparent polymer film, a
laminate structure in which a metal oxide layer and a metal layer
are laminated, the metal oxide layer containing an organic
component; and a groove formation process forming grooves having a
width of 30 .mu.m or less in a formed laminate structure so that an
overall surface resistance of the transparent laminate film is
150.OMEGA./.quadrature. or more. Therefore, a transparent laminate
film of the above described configuration can be suitably
produced.
[0046] Further, in the case where the formation of the grooves is
performed by causing the organic component in the metal oxide layer
containing the organic component to react to cause cracks to form
due to a stress generated in the laminate structure during the
reaction, numerous cracks can be formed in the laminate structure
as grooves. Therefore, directionality in the surface resistance is
unlikely to appear, and a transparent laminate film having superior
uniformity in the surface resistance can be obtained. Further,
cracks can be introduced in a relatively short time. Therefore, the
transparent laminate film has a superior mass productivity.
[0047] Further, in the case where the organic component is a
remaining component of a starting material of a sol-gel method and
the formation of the grooves include a step applying energy to the
laminate structure from the surface thereof in an atmosphere
containing one kind or two or more kinds of materials selected from
oxygen, ozone, and water, the one kind or two or more kinds of
materials selected from oxygen, ozone, and water contained in the
atmosphere cause the remaining component to undergo a sol-gel
reaction, so that cracks are induced in the metal oxide layer by
cure shrinkage, and, using these cracks as base points, the cracks
can be propagated into the laminate structure. Therefore, hardly
visible cracks can be relatively simply introduced into the
laminate structure, and a predetermined surface resistance can be
ensured.
[0048] Further, in the case where the formation of the grooves is
performed by subjecting the surface of the laminate structure to
laser processing, grooves can be formed in any form such as
lattice-like, strip-like, slit-like, and the like.
[0049] Further, in the case where the formation of the grooves is
performed by stretching the transparent laminate film, hardly
visible cracks can be relatively simply introduced into the
laminate structure, and a predetermined surface resistance can be
ensured. In particular, when the stretching is a biaxial
stretching, non-directional cracks are easily formed. Therefore,
directionality in the surface resistance is unlikely to appear, and
a transparent laminate film having superior uniformity in the
surface resistance can be obtained.
[0050] The other method for producing a transparent laminate film
according to the present invention includes preparing a transparent
polymer film having an easy adhesion layer formed on at least one
side thereof; forming a laminate structure by laminating a metal
oxide layer and a metal layer on top of the easy adhesion layer on
the at least one side, the metal oxide layer containing an organic
component; and forming numerous cracks having a width of 30 .mu.m
or less in the laminate structure so that an overall surface
resistance of the transparent laminate film is
150.OMEGA./.quadrature. or more.
[0051] Therefore, simultaneously with the formation of the laminate
structure, the continuity of the metal layer can be broken due to
the cracks, and thus the groove formation process after the
lamination process can be omitted. Therefore, the transparent
laminate film has a superior mass productivity, which can
contribute to cost reduction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] FIG. 1 is a diagram illustrating a relation between surface
resistance (.OMEGA./.quadrature.) and transmission attenuation
(dB);
[0053] FIG. 2(a) is a diagram of a transparent laminate film viewed
from a surface side of a laminate structure, illustrating slit-like
grooves;
[0054] FIG. 2(b) is a diagram of a transparent laminate film viewed
from a surface side of a laminate structure, illustrating
lattice-like grooves;
[0055] FIG. 3 is an optical micrograph of a transparent laminate
film according to a comparative example 4, viewed from a surface
side of a laminate structure;
[0056] FIG. 4 is an optical micrograph of a transparent laminate
film according to embodiment 2, viewed from a surface side of a
laminate structure (for a case where grooves are cracks formed by
ozone ashing);
[0057] FIG. 5 is an optical micrograph of a transparent laminate
film according to embodiment 4, viewed from a surface side of a
laminate structure (for a case where grooves are formed by laser
processing);
[0058] FIG. 6 is an enlarged photograph of FIG. 5;
[0059] FIG. 7 is an optical micrograph of a transparent laminate
film according to embodiment 7, viewed from a surface side of a
laminate structure (for a case where grooves are cracks formed by a
uniaxial stretching);
[0060] FIG. 8 is an optical micrograph of a transparent laminate
film according to embodiment 8, viewed from a surface side of a
laminate structure (for a case where grooves are cracks formed by a
biaxial stretching); and
[0061] FIG. 9 is an optical micrograph of a transparent laminate
film according to embodiment 10, viewed from a surface side of a
laminate structure (for a case where grooves are cracks formed
during formation of the laminate structure).
MODE FOR CARRYING OUT THE INVENTION
[0062] A transparent laminate film (which may be referred to as
"the present film" in the following) and a method for producing the
same (which may be referred to as "the present production method"
in the following) according to the present embodiment are explained
in detail.
[0063] 1. The Present Film
[0064] The present film includes a transparent polymer film and a
laminate structure. The laminate structure may be formed on any one
side of the transparent polymer film or on both sides of the
transparent polymer film. From a point of view of cost and the
like, it is desirable that the laminate structure be formed on one
side of the transparent polymer film.
[0065] In the present film, the transparent polymer film acts as a
base material for forming the laminate structure. As a material of
the transparent polymer film, any material can be used that has
transparency in a visible light region and a thin film can be
formed without any difficulty on a surface thereof.
[0066] Examples of the material of the transparent polymer film
include, specifically, for example, polymer materials such as
polyethylene terephthalate, polycarbonate, polymethyl methacrylate,
polyethylene, polypropylene, ethylene-vinyl acetate copolymer,
polystyrene, polyimide, polyamide, polybutylene terephthalate,
polyethylene naphthalate, polysulfone, polyether sulfone, polyether
ether ketone, polyvinyl alcohol, polyvinyl chloride, polyvinylidene
chloride, triacetyl cellulose, polyurethane, cyclo-olefin polymer,
and the like. One kind or two or more kinds of these materials may
be contained. Further, two or more kinds of transparent polymers
can be laminated and used.
[0067] Among these material, from a point of view of having
superior transparency, durability, workability, and the like,
polyethylene terephthalate, polycarbonate, polymethyl methacrylate,
cyclo-olefin polymer, and the like are examples of particularly
preferred materials.
[0068] The transparent polymer film may have a surface treatment
layer such as an easy adhesion layer and the like formed on one
side or both sides of the transparent polymer film. The easy
adhesive layer is mainly for a purpose of improving winding
workability and handling workability of the transparent polymer
film. In particular, such an easy adhesion layer is often formed on
a transparent polymer film for optical applications for which
silica particles or the like are mixed in the film or are attached
to a surface of the film so that the above mentioned purpose is
difficult to achieve.
[0069] Examples of a polymer material constituting the easy
adhesion layer include, for example, acrylic resins, urethane
resins, polyester resins, acrylic-urethane resins, and the like. In
the easy adhesion layer, silica particles, polyethylene particles,
and the like may be dispersed.
[0070] Thickness of the easy adhesion layer is not particularly
limited. From a point of view of adhesiveness, transparency, cost,
and the like, it is desirable that the thickness of the easy
adhesion layer have an upper limit of preferably 20 .mu.m or less,
more preferably 10 .mu.m or less, and even more preferably 5 .mu.m
or less. On the other hand, from a point of view of effect
realization, it is desirable that the thickness of the easy
adhesion layer have a lower limit of preferably 0.5 .mu.m or more,
more preferably 0.8 .mu.m or more, and even more preferably 1.0
.mu.m or more.
[0071] When the transparent polymer film has the easy adhesion
layer, it is desirable that the laminate structure be formed on top
of the easy adhesion layer. When the laminate structure is formed
on top of the easy adhesion layer, a phenomenon is seen that cracks
are easily formed in the layers constituting the laminate structure
during the formation of the laminate structure. Therefore, the
laminate structure formed on top of the easy adhesion layer has
cracks formed during the formation of the laminate structure. These
cracks are used as grooves, thereby, the continuity of a metal
layer constituting the laminate structure can be broken (metal
layer, grooves, and the like will be described in detail
later).
[0072] Thickness of the transparent polymer film can be adjusted in
various ways taking into account an intended purpose of the present
film, the material of the present film, optical characteristics,
durability, and the like. From a point of view of being hard for
wrinkles to occur and hard to be broken during processing, it is
desirable that the thickness of the transparent polymer film have a
lower limit of preferably 25 .mu.m or more, and more preferably 50
.mu.m or more. On the other hand, from a point of view of being
easy to be wound, economic efficiency, and the like, it is
desirable that the thickness of the transparent polymer film have
an upper limit of preferably 500 .mu.m or less, and more preferably
250 .mu.m or less.
[0073] In the present film, the laminate structure is formed by
laminating a plurality of thin film layers and contains at least a
metal oxide layer (which may be sometimes referred to as an "MO
layer" in abbreviation in the following) and a metal layer (which
may be sometimes referred to as an "M layer" in abbreviation in the
following). Further, a barrier layer (which may be sometimes
referred to as a "B layer" in abbreviation in the following) may be
formed on any one side or both sides of the metal layer (M
layer).
[0074] Examples of a basic structure of the laminate structure
includes a laminate structure and the like in which the metal oxide
layer (MO layer) and the metal layer (M layer) are alternately
laminated.
[0075] Examples of a basic unit of the laminate structure include,
specifically, for example, first basic units such as, from the
transparent polymer film side, MO layer|B layer/M layer/B layer, MO
layer|M layer/B layer, MO layer|B layer/M layer, or second basic
units such as, from the transparent polymer film side, B layer/M
layer/B layer|MO layer, M layer/B layer|MO layer, B layer/M
layer|MO layer, and the like. Here, "|" means a layer separator;
and "/" means that a B layer is attached to an M layer.
[0076] The laminate structure may be formed by laminating singly or
repeatedly one basic unit or two or more basic units selected from
the first basic units, and may also be formed by laminating singly
or repeatedly one basic unit or two or more basic units selected
from the second basic units.
[0077] Among these, from a point of view of being easy to inhibit
diffusion of an element constituting the M layer into the MO layer,
the unit of MO layer|B layer/M layer/B layer in the case of the
first basic units and the unit of B layer/M layer/B layer|MO layer
in the case of the second basic units can be preferably
selected.
[0078] Among the thin film layers constituting the laminate
structure, it is desirable that a thin film layer in contact with
the transparent polymer film be a metal oxide layer (MO layer).
This is because of advantages of being superior in optical
characteristics such as high visible light transparency, low
visible light reflection, and the like. Further, among the thin
film layers constituting the laminate structure, it is desirable
that a thin film layer arranged as an outermost layer be a metal
oxide layer (MO layer). This is because of advantages such as being
easy for grooves to form and the like, which will be described
later (in particular for the case of cracks).
[0079] The number of laminating layers of the laminate structure
can be varied taking into account optical characteristics such as
visible light transparency, solar radiation shielding capability,
and the like, overall surface resistance of the film, material and
film thickness of each thin film layer, production cost, and the
like. As the number of laminating layers, 2-10 layers and the like
are preferable. Odd number of layers such as 3 layers, 5 layers, 7
layers, 9 layers, and the like are more preferable. From a point of
view of production cost and the like, 3 layers, 5 layers and 7
layers are even more preferable.
[0080] More specifically, from a point of view of being easy to
achieve a balance between transparency and solar radiation
shielding capability, suppression of production cost, and the like,
examples of preferred structures as the laminate structure include
three-layer laminate structures such as MO layer (first layer)|B
layer/M layer/B layer (second layer)|MO layer (third layer), MO
layer (first layer)|B layer/M layer (second layer)|MO layer (third
layer), MO layer (first layer)|M layer/B layer (second layer)|MO
layer (third layer), MO layer (first layer)|M layer (second
layer)|MO layer (third layer), and the like, five-layer laminate
structures such as MO layer (first layer)|B layer/M layer/B layer
(second layer)|MO layer (third layer)|B layer/M layer/B layer
(fourth layer)|MO layer (fifth layer), MO layer (first layer)|B
layer/M layer (second layer)|MO layer (third layer)|B layer/M layer
(fourth layer)|MO layer (fifth layer), MO layer (first layer)|M
layer/B layer (second layer)|MO layer (third layer)|M layer/B layer
(fourth layer)|MO layer (fifth layer), MO layer (first layer)|M
layer (second layer)|MO layer (third layer)|M layer (fourth
layer)|MO layer (fifth layer), and the like, and seven-layer
laminate structures such as MO layer (first layer)|B layer/M
layer/B layer (second layer)|MO layer (third layer)|B layer/M
layer/B layer (fourth layer)|MO layer (fifth layer)|B layer/M
layer/B layer (sixth layer)|MO layer (seventh layer), MO layer
(first layer)|B layer/M layer (second layer)|MO layer (third
layer)|B layer/M layer (fourth layer)|MO layer (fifth layer)|B
layer/M layer (sixth layer)|MO layer (seventh layer), MO layer
(first layer)|M layer/B layer (second layer)|MO layer (third
layer)|M layer/B layer (fourth layer)|MO layer (fifth layer)|M
layer/B layer (sixth layer)|MO layer (seventh layer), MO layer
(first layer)|M layer (second layer)|MO layer (third layer)|M layer
(fourth layer)|MO layer (fifth layer)|M layer (sixth layer)|MO
layer (seventh layer), and the like, from the transparent polymer
film side.
[0081] Further, the examples of preferred structures as the
laminate structure include three-layer laminate structures such as
B layer/M layer/B layer (first layer)|MO layer (second layer)|B
layer/M layer/B layer (third layer), B layer/M layer (first
layer)|MO layer (second layer)|B layer/M layer (third layer), M
layer/B layer (first layer)|MO layer (second layer)|M layer/B layer
(third layer), M layer (first layer)|MO layer (second layer)|M
layer (third layer), and the like, five-layer laminate structures
such as B layer/M layer/B layer (first layer)|MO layer (second
layer)|B layer/M layer/B layer (third layer)|MO layer (fourth
layer)|B layer/M layer/B layer (fifth layer), B layer/M layer
(first layer)|MO layer (second layer)|B layer/M layer (third
layer)|MO layer (fourth layer)|B layer/M layer (fifth layer), M
layer/B layer (first layer)|MO layer (second layer)|M layer/B layer
(third layer)|MO layer (fourth layer)|B layer/M layer (fifth
layer), M layer (first layer)|MO layer (second layer)|M layer
(third layer)|MO layer (fourth layer)|M layer (fifth layer), and
the like, and seven-layer laminate structures such as B layer/M
layer/B layer (first layer)|MO layer (second layer)|B layer/M
layer/B layer (third layer)|MO layer (fourth layer)|B layer/M
layer/B layer (fifth layer)|MO layer (sixth layer)|B layer/M
layer/B layer (seventh layer), B layer/M layer (first layer)|MO
layer (second layer)|B layer/M layer (third layer)|MO layer (fourth
layer)|B layer/M layer (fifth layer)|MO layer (sixth layer)|B
layer/M layer (seventh layer), M layer/B layer (first layer)|MO
layer (second layer)|M layer/B layer (third layer)|MO layer (fourth
layer)|M layer/B layer (fifth layer)|MO layer (sixth layer)|M
layer/B layer (seventh layer), M layer (first layer)|MO layer
(second layer)|M layer (third layer)|MO layer (fourth layer)|M
layer (fifth layer)|MO layer (sixth layer)|M layer (seventh layer),
and the like, from the transparent polymer film side.
[0082] A B layer is a thin film layer associated with an M layer.
Therefore, for the number of laminating layers in the present
application, an M layer including a B layer is counted as one
layer, and an MO layer is counted as one layer.
[0083] In the present film, each thin film layer may be formed at
once or may be formed in a divided manner. Further, some or all of
the thin film layers contained in the laminate structure may be
formed in a divided manner. In a case where each thin film layer is
composed of a plurality of divisional layers, the number of
divisions for each of the thin film layers may be the same or may
be different. A divisional layer is not counted as one laminating
layer. One thin film layer formed by a collection of a plurality of
divisional layers is counted as one layer.
[0084] In the present film, composition and material of each thin
film layer may be formed by the same composition or material, and
may also be formed by different composition or material. This point
also applies to the case where each thin film layer is formed from
a plurality of divisional layers.
[0085] Film thickness of each thin film layer may be the same, and
may also be different for each individual film.
[0086] The present film, roughly, has the laminate structure
described above. Grooves are formed in this laminate structure. The
grooves have primarily a role to break the continuity of the metal
layer contained in the laminate structure, increase the surface
resistance, and ensure radio wave transparency. The grooves have a
width of 30 .mu.m or less. The reason that the width of the grooves
is limited to 30 .mu.m or less is because that, when the width is
above 30 .mu.m, the grooves become easily visible and appearance
deteriorates. From a point of view of appearance and the like, it
is desirable that the width of the grooves be preferably 20 .mu.m
or less, and more preferably 10 .mu.m or less. The width of the
grooves is an average value of widths obtained by capturing five
images of a surface of the laminate structure using an optical
microscope and measuring with respect to grooves at three spots for
each image (total fifteen spots).
[0087] There is no particular restriction with regard to a lower
limit of the width of the grooves. However, from a point of view of
surface resistance and the like, it is desirable that the lower
limit of the width of the grooves be preferably 0.05 .mu.m or more,
and more preferably 0.1 .mu.m or more.
[0088] With regard to a thickness-wise direction of the laminate
structure, as far as the surface resistance is below a later
described predetermined value, the grooves may have any depth. All
of the grooves may have the same depth from the surface of the
laminate structure, and each of the grooves may also have a
different depth from the surface of the laminate structure.
[0089] Examples of shapes of the grooves include, for example,
regular shapes such as a lattice-like shape, a slit-like shape, and
the like, and irregular shapes such as cracks and the like. Shapes
such as the lattice-like shape, the slit-like shape, and the like,
for example, can be formed by subjecting the surface of the
laminate structure to laser processing and the like. Whether a
groove is formed by laser processing can often be confirmed by
observing an edge of the groove. Cracks can be formed by causing a
stress to be generated in a formed laminate structure. Or, cracks
can also be formed during formation of a laminate structure. It is
preferable that there are an infinite number of cracks. This is
because directionality in the surface resistance, which will be
described later, is unlikely to appear, which contributes to
uniformity of the surface resistance.
[0090] The present film has an overall surface resistance of
150.OMEGA./.quadrature. or more. There is a close relationship
between the surface resistance of the film and the transmission
attenuation of a radio wave. That is, in practice, in order to have
radio wave transparency, it is desirable that 1/5 or more of radio
wave energy be allowed to pass through. In order to allow 1/5 or
more of the radio wave energy to pass through, the transmission
attenuation needs to be 7 db or less. In order for the transmission
attenuation to be 7 db or less, the overall surface resistance of
the film needs to be 150.OMEGA./.quadrature. or more. In the
present application, in order to achieve this, grooves are formed
in the laminate structure.
[0091] From a point of view of improving radio wave transparency,
it is desirable that the surface resistance be preferably
170.OMEGA./.quadrature. or more, more preferably
200.OMEGA./.quadrature. or more, and even more preferably
300.OMEGA./.quadrature. or more. There is no particular restriction
with regard to an upper limit of the surface resistance. However,
from a point of view of solar radiation shielding capability,
transparency, appearance, and the like, it is desirable that the
upper limit of the surface resistance be preferably
1000.OMEGA./.quadrature. or less, and more preferably
800.OMEGA./.quadrature. or less. The surface resistance can be
measured using an eddy current meter and the like.
[0092] In the following, the metal oxide layers (MO layers) and
metal layers (M layers) that constitute the laminate structure of
the present film, and the barrier layers (B layers) that may be
optionally included in the laminate structure of the present film,
are explained in detail.
[0093] <Metal Oxide Layer>
[0094] In the present film, a metal oxide layer has transparency in
the visible light region, and acts primarily as a high refractive
index layer. Here, a high refractive index means a refractive index
of 1.7 or more with respect to light of 633 nm.
[0095] Examples of the above metal oxide include, specifically, for
example, titanium oxide, zinc oxide, indium oxide, tin oxide, oxide
of indium and tin, magnesium oxide, aluminum oxide, zirconium
oxide, niobium oxide, cerium oxide, and the like. One kind or two
or more kinds of these materials may be contained. Further, these
metal oxides may also be complex oxides that combine two or more
kinds of metal oxides.
[0096] In particular, from a point of view of having a relatively
large refractive index with respect to visible light and the like,
examples of suitable materials as the above metal oxide include
titanium oxide (TiO.sub.2), ITO, zinc oxide (ZnO), tin oxide
(SnO.sub.2), and the like. One kind or two or more kinds of these
materials may be contained.
[0097] Here, the metal oxide layer is mainly composed of the above
described metal oxides. However, in addition to the metal oxides,
an organic component may also be contained. This is because
containing an organic component can further improve the flexibility
of the present film. Examples of an organic component of this kind
include, specifically, for example, components originating from a
starting material of a sol-gel method, components originating from
a material for forming the metal oxide layers, and the like.
[0098] Examples of the above organic component include, more
specifically, for example, organic metallic compounds (including
also decomposed materials thereof) such as metal alkoxides, metal
acylates, metal chelates, and the like, of metals constituting the
above described metal oxides, various kinds of additives such as
organic compounds (described later) for forming ultraviolet
absorbing chelates by reacting with the above organic metallic
compounds, and the like. One kind or two or more kinds of these
materials may be contained.
[0099] From a point of view of being easy to impart flexibility and
the like, it is desirable that content of the organic component
contained in the metal oxide layers have a lower limit of
preferably 3% by mass or more, more preferably 5% by mass or more,
and even more preferably 7% by mass or more. On the other hand,
from a point of view of being likely to ensure a high refractive
index, being likely to ensure solvent resistance, and the like, it
is desirable that the content of the organic component contained in
the metal oxide layers have an upper limit of preferably 30% by
mass or less, more preferably 25% by mass or less, and even more
preferably 20% by mass or less.
[0100] The content of the organic component can be examined using
an X-ray photoelectron spectroscopy (XPS) or the like. The type of
the organic component can be examined using an infrared
spectroscopy (IR) (infrared absorption analysis) or the like.
[0101] The film thickness of the metal oxide layers can be adjusted
by considering solar radiation shielding capability, visibility,
reflected color, and the like.
[0102] From a point of view of being easy to inhibit red and yellow
coloration of reflected color, being easy to obtain high
transparency, and the like, it is desirable that the film thickness
of the metal oxide layers have a lower limit of preferably 10 nm or
more, more preferably 15 nm or more, and even more preferably 20 nm
or more. On the other hand, from a point of view of being easy to
inhibit green coloration of reflected color, being easy to obtain
high transparency, and the like, it is desirable that the film
thickness of the metal oxide layers have an upper limit of
preferably 90 nm or less, more preferably 85 nm or less, and even
more preferably 80 nm or less.
[0103] The metal oxide layers having the above described
configuration, can be formed using any one of a gas phase method
and a liquid phase method. The liquid phase method, as compared to
the gas phase method, does not require vacuuming and using high
power. Therefore, the liquid phase method is cost effective, and is
also superior in productivity, and is thus preferable.
[0104] As the liquid phase method, from a point of view of being
easy for an organic component to remain, and the like, a sol-gel
method can be preferably used.
[0105] Examples of the sol-gel method include, more specifically,
for example, a method and the like in which a coating liquid
containing an organic metallic compound of a metal that constitutes
a metal oxide is coated in a thin film shape, which is dried as
needed to form a precursor layer of a metal oxide layer, and
thereafter, the organic metallic compound contained in this
precursor layer is caused to undergo a hydrolysis and condensation
reaction to synthesize an oxide of the metal that constitutes the
organic metallic compound. According to this, a metal oxide layer,
containing a metal oxide as a main component and an organic
component, can be formed. In the following, the above method is
explained in detail.
[0106] The coating liquid can be prepared by dissolving the above
organic metallic compound in a suitable solvent. In this case,
examples of the organic metallic compound include, specifically,
for example, organic metallic compounds of metals such as titanium,
zinc, indium, tin, magnesium, aluminum, zirconium, niobium, cerium,
silicon, hafnium, lead, and the like. One kind or two or more kinds
of these materials may be contained.
[0107] Examples of the organic metallic compound include,
specifically, for example, metal alkoxides, metal acylates, metal
chelates, and the like, of the above metals. From a point of view
of stability in the air, the metal chelates are preferable.
[0108] As the organic metallic compound, in particular, an organic
compound of a metal that can lead to a metal oxide having a high
refractive index can be preferably used. Examples of such an
organic metallic compound include, for example, an organic titanium
compound and the like.
[0109] Examples of the organic titanium compound include,
specifically, for example, titanium alkoxides having a M-O--R bond
(where R denotes an alkyl group and M denotes a titanium atom) such
as tetra-n-butoxy titanium, tetraethoxy titanium, tetra-i-propoxy
titanium, tetramethoxy titanium, and the like; titanium acylates
having a M-O--CO--R bond (where R denotes an alkyl group and M
denotes a titanium atom) such as isopropoxy titanium stearate, and
the like; titanium chelates such as diisopropoxy titanium bis
acetylacetonato, dihydroxy bis lactato titanium, diisopropoxy bis
triethanol aminato titanium, diisopropoxy his ethyl acetoacetate
titanium, and the like; and the like. One kind or two or more kinds
of these compounds may be mixed. Further, these compounds may be
monomers or polymers.
[0110] From a point of view of film thickness uniformity of a
coated film, film thickness achievable by one coating, and the
like, it is desirable that content of an organic metallic compound
in the coating liquid be within a range of preferably 1-20% by
mass, more preferably 3-15% by mass, and even more preferably 5-10%
by mass.
[0111] Examples of a solvent dissolving the organic metallic
compound include, specifically, for example, alcohols such as
methanol, ethanol, propanol, butanol, heptanol, isopropyl alcohol,
and the like; organic acid esters such as ethyl acetate, and the
like; ketones such as acetonitrile, acetone, methyl ethyl ketone,
and the like; cyclo ethers such as tetrahydrofuran, dioxane, and
the like; acid amides such as formamide, N,N-dimethylformamide, and
the like; hydrocarbons such as hexane and the like; aromatic series
such as toluene and the like; and the like. One kind or two or more
kinds of these compounds may be mixed.
[0112] In this case, from a point of view of film thickness
uniformity of a coated film, film thickness achievable by one
coating, and the like, it is desirable that an amount of the
solvent be within a range of preferably 5-100 times, more
preferably 7-30 times, and even more preferably 10-20 times of an
amount of a solid component of the organic metallic compound.
[0113] When the amount of the solvent is more than 100 times, the
film thickness achieved by one coating becomes thinner, and, in
order to achieve a desired film thickness, there is a tendency that
multiple times of coating become necessary. On the other hand, when
the amount of the solvent is less than 5 times, there is a tendency
that the film thickness becomes too thick and the hydrolysis and
condensation reaction of the organic metallic compound becomes
difficult to proceed sufficiently. Therefore, it is desirable that
the amount of the solvent be selected taking these factors into
consideration.
[0114] From a point of view of promoting hydrolysis using a sol-gel
method, being likely to achieve a high refractive index, and the
like, the coating liquid may contain water as needed.
[0115] The coating liquid can be prepared, for example, by a method
such as stirring and mixing the organic metallic compound weighed
so as to achieve a predetermined ratio, an appropriate amount of
the solvent, and other ingredients added as needed, for a
predetermined period of time using a stirring means such as a
stirrer and the like. In this case, the mixing of the components
may be done at one time or may be divided into multiple times.
[0116] From a point of view of facilitating a uniform coating,
examples of a preferable coating method of the above coating liquid
include various wet coating methods such as a micro gravure method,
a gravure method, a reverse roll coating method, a dye coating
method, a knife coating method, a dip coating method, a spin
coating method, a bar coating method, and the like. These methods
can be appropriately selected and used. One kind or two or more
kinds of these methods may be used in combination.
[0117] When drying a coated coating liquid, a conventional drying
equipment and the like may be used. In this case, examples of
drying conditions include, specifically, for example, a temperature
range of 80.degree. C.-120.degree. C., a drying time of 0.5
minute-5 minutes, and the like.
[0118] Examples of various means for causing the organic metallic
compound in the precursor layer to undergo a hydrolysis and
condensation reaction include, specifically, for example,
irradiation of optical energy such as ultraviolet light, an
electron beam, X-ray, and the like, heating, and the like. One kind
or two or more kinds of these may be combined and used. Among
these, the irradiation of optical energy, in particular, the
ultraviolet irradiation, can be preferably used. This is because,
as compared to other means, a metal oxide can be produced at a low
temperature and in a short time, and it is less likely to add a
thermal load such as thermal degradation and the like to the
transparent polymer film (in particular, for the case of
ultraviolet irradiation, there is an advantage that only a
relatively simple equipment is required). Further, there is
advantage that it is likely for the organic metallic compound
(including decomposed materials thereof) to remain as the organic
component.
[0119] In this case, examples of an ultraviolet irradiation
equipment include, specifically, for example, a mercury lamp, an
xenon lamp, a deuterium lamp, an excimer lamp, a metal halide lamp,
and the like. One kind or two or more kinds of these may be
combined and used.
[0120] Intensity of irradiating optical energy can be adjusted in
various ways taking into consideration the type of the organic
metallic compound from which the precursor layer is primarily
formed, the thickness of the coating layer, and the like. When the
intensity of the irradiating optical energy is too small, a high
refractive index of the metal oxide layer is hard to achieve. On
the other hand, when the intensity of the irradiating optical
energy is too large, the transparent polymer film may deform due to
heat generated during the optical energy irradiation. Therefore, it
is preferred to pay attention to these factors.
[0121] In the case where the irradiating optical energy is
ultraviolet light, from a point of view of the refractive index of
the metal oxide layer, damage received by the transparent polymer
film, and the like, when a measurement wavelength is within a range
of 300-390 nm, it is desirable that the intensity of the
ultraviolet light be within a range of preferably 300-8000
mJ/cm.sup.2, and more preferably 500-5000 mJ/cm.sup.2.
[0122] When the optical energy irradiation is used as a means for
causing the organic metallic compound in the precursor layer to
undergo a hydrolysis and condensation reaction, it is desirable
that an additive such as an organic compound and the like that
reacts with the organic metallic compound to form a light absorbing
(for example, ultraviolet light absorbing) chelate be added to the
above described coating liquid. When the additive is added to the
coating liquid, which is a starting solution, a place where a light
absorbing chelate was formed in advance is irradiated with optical
energy. Therefore, a high refractive index of a metal oxide layer
can be easily achieved at a relatively low temperature.
[0123] Examples of the above additive include, specifically, for
example, such as .beta. diketones, alkoxy alcohols, alkanolamines,
and the like. More specifically, examples of the .beta. diketones
include, for example, acetylacetone, benzoylacetone, ethyl
acetoacetate, methyl acetoacetate, diethyl malonate, and the like.
Examples of the alkoxy alcohols include, for example,
2-methoxyethanol, 2-ethoxyethanol, 2-methoxy-2-propanol, and the
like. Examples of the alkanolamines include, for example,
monoethanolamine, diethanolamine, triethanolamine, and the like.
One kind or two or more kinds of these compounds may be mixed.
[0124] Among these, the .beta. diketones are particularly
preferable. Among the .beta. diketones, the acetylacetone can be
most preferably used.
[0125] From a point of view of likely increasing the refractive
index, stability of a state of a coated film, and the like, it is
desirable that a mixing ratio of the above additive be within a
range of preferably 0.1-2 moles, and more preferably 0.5-1.5 moles,
with respect to 1 mole of metal atoms in the above organic metallic
compound.
[0126] <Metal Layer>
[0127] In the present film, a metal layer primarily acts as a solar
radiation shielding layer and the like.
[0128] Examples of the metal include, specifically, for example,
metals such as silver, gold, platinum, copper, aluminum, chromium,
titanium, zinc, tin, nickel, cobalt, niobium, tantalum, tungsten,
zirconium, lead, palladium, indium, and the like; alloys of these
metals; and the like. One kind or two or more kinds of these
materials may be contained.
[0129] From a point of view of being superior in visible light
transparency, heat ray reflectivity, electrical conductivity, and
the like for a lamination, it is desirable that the above metal be
silver or a silver alloy. From a point of view of improving
durability with respect to an environment of heat, light, moisture,
and the like, it is more desirable that the metal be a silver alloy
containing silver as a primary component and at least one or more
metallic elements such as copper, bismuth, gold, palladium,
platinum, titanium, and the like. It is even more desirable that
the metal be a copper-containing silver alloy (Ag--Cu based alloy),
a bismuth-containing silver alloy (Ag--Bi based alloy),
titanium-containing silver alloy (Ag--Ti based alloy), or the like.
This is because of advantages such as a large silver diffusion
inhibition effect, being cost effective, and the like.
[0130] When a copper-containing silver alloy is used, in addition
to silver and copper, other elements and unavoidable impurities may
also be contained as far as they do not adversely affect, for
example, silver aggregation and diffusion inhibition effects.
[0131] Examples of the above-mentioned other elements include,
specifically, for example, elements solid-soluble in Ag such as Mg,
Pd, Pt, Au, Zn, Al, Ga, In, Sn, Sb, Li, Cd, Hg, As, and the like;
elements that can be precipitated as a single phase in an Ag--Cu
based alloy such as Be, Ru, Rh, Os, Ir, Bi, Ge, V, Nb, Ta, Cr, Mo,
W, Mn, Re, Fe, Co, Ni, Si, Tl, Pb, and the like; elements that can
precipitate an intermetallic compound with Ag such as Y, La, Ce,
Nd, Sm, Gd, Tb, Dy, Ti, Zr, Hf, Na, Ca, Sr, Ba, Sc, Pr, Eu, Ho, Er,
Tm, Yb, Lu, S, Se, Te, and the like; and the like. One kind or two
or more kinds of these elements may be contained.
[0132] When a copper-containing silver alloy is used, from a point
of view of obtaining an additive effect, it is desirable that
copper content have a lower limit of preferably 1% by atom or more,
more preferably 2% by atom or more, and even more preferably 3% by
atom or more. On the other hand, from a point of view of being easy
to ensure high transparency, manufacturability such as easy
preparation of a sputtering target, and the like, it is desirable
that the content of copper have an upper limit of preferably 20% by
atom or less, more preferably 10% by atom or less, and even more
preferably 5% by atom or less.
[0133] When a bismuth-containing silver alloy is used, in addition
to silver and bismuth, other elements and unavoidable impurities
may also be contained as far as they do not adversely affect, for
example, the silver aggregation and diffusion inhibition
effects.
[0134] Examples of the above-mentioned other elements include,
specifically, for example, elements solid-soluble in Ag such as Mg,
Pd, Pt, Au, Zn, Al, Ga, In, Sn, Sb, Li, Cd, Hg, As, and the like;
elements that can be precipitated as a single phase in an Ag--Bi
based alloy such as Be, Ru, Rh, Os, Ir, Cu, Ge, V, Nb, Ta, Cr, Mo,
W, Mn, Re, Fe, Co, Ni, Si, Tl, Pb, and the like; elements that can
precipitate an intermetallic compound with Ag such as Y, La, Ce,
Nd, Sm, Gd, Tb, Dy, Ti, Zr, Hf, Na, Ca, Sr, Ba, Sc, Pr, Eu, Ho, Er,
Tm, Yb, Lu, S, Se, Te, and the like; and the like. One kind or two
or more kinds of these elements may be contained.
[0135] When a bismuth-containing silver alloy is used, from a point
of view of obtaining an additive effect, it is desirable that
bismuth content have a lower limit of preferably 0.01% by atom or
more, more preferably 0.05% by atom or more, and even more
preferably 0.1% by atom or more. On the other hand, from a point of
view of manufacturability such as easy preparation of a sputtering
target, and the like, it is desirable that the content of bismuth
have an upper limit of preferably 5% by atom or less, more
preferably 2% by atom or less, and even more preferably 1% by atom
or less.
[0136] When a titanium-containing silver alloy is used, in addition
to silver and titanium, other elements and unavoidable impurities
may also be contained as far as they do not adversely affect, for
example, the silver aggregation and diffusion inhibition
effects.
[0137] Examples of the above-mentioned other elements include,
specifically, for example, elements solid-soluble in Ag such as Mg,
Pd, Pt, Au, Zn, Al, Ga, In, Sn, Sb, Li, Cd, Hg, As, and the like;
elements that can be precipitated as a single phase in an Ag--Ti
based alloy such as Be, Ru, Rh, Os, Ir, Cu, Ge, V, Nb, Ta, Cr, Mo,
W, Mn, Re, Fe, Co, Ni, Si, Tl, Pb, Bi and the like; elements that
can precipitate an intermetallic compound with Ag such as Y, La,
Ce, Nd, Sm, Gd, Tb, Dy, Zr, Hf, Na, Ca, Sr, Ba, Sc, Pr, Eu, Ho, Er,
Tm, Yb, Lu, S, Se, Te, and the like; and the like. One kind or two
or more kinds of these elements may be contained.
[0138] When a titanium-containing silver alloy is used, from a
point of view of obtaining an additive effect, it is desirable that
titanium content have a lower limit of preferably 0.01% by atom or
more, more preferably 0.05% by atom or more, and even more
preferably 0.1% by atom or more. On the other hand, from a point of
view of being easy to obtain a complete solid solution when a film
is formed, and the like, it is desirable that the content of
titanium have an upper limit of preferably 2% by atom or less, more
preferably 1.75% by atom or less, and even more preferably 1.5% by
atom or less.
[0139] Ratio of a secondary element such as the above-mentioned
copper, bismuth, titanium, and the like can be measured using ICP
analysis. A metal (alloy) constituting the metal layer may be
partially oxidized.
[0140] From a point of view of stability, heat ray reflectivity,
and the like, it is desirable that the film thickness of the metal
layer have a lower limit of preferably 3 nm or more, more
preferably 5 nm or more, and even more preferably 7 nm or more. On
the other hand, from a point of view of visible light transparency,
economic efficiency, and the like, it is desirable that the film
thickness of the metal layer have an upper limit of preferably 30
nm or less, more preferably 20 nm or less, and even more preferably
15 nm or less.
[0141] Here, examples of a method for forming the metal layer
include gas phase methods, specifically, for example, physical
vapor deposition methods (PVD) such as a vacuum deposition method,
a sputtering method, an ion plating method, an MBE method, a laser
ablation method, and the like; chemical vapor deposition methods
(CVD) such as a thermal CVD method, a plasma CVD method, and the
like; and the like. The metal layer may be formed by using any one
of these methods, or may be formed by using two or more of these
methods.
[0142] Among these methods, from a point of view of being able to
obtain a dense film quality, being relatively easy to control film
thickness, and the like, the sputtering method such as a DC
magnetron sputtering method, an RF magnetron sputtering method, and
the like can be preferably used.
[0143] The metal layer may be oxidized by subjecting the metal
layer to post-oxidization and the like, which will be described
later, as far as functional capabilities of the metal layer are not
impaired.
[0144] <Barrier Layer>
[0145] In the present film, a barrier layer primarily acts as a
barrier inhibiting diffusion of elements constituting the metal
layer into the metal oxide layer. Further, by intervening between
the metal oxide layer and the metal layer, the barrier layer also
contributes to improvement of adhesion between the metal oxide
layer and the metal layer.
[0146] As far as being able to inhibit the diffusion, the barrier
layer may even have a discontinuous part such as a part in a shape
of a floating island.
[0147] Examples of a metal oxide constituting the barrier layer
include, specifically, for example, titanium oxide, zinc oxide,
indium oxide, tin oxide, oxide of indium and tin, magnesium oxide,
aluminum oxide, zirconium oxide, niobium oxide, cerium oxide, and
the like. One kind or two or more kinds of these materials may be
contained. Further, these metal oxides may also be complex oxides
that combine two or more kinds of metal oxides. Besides the metal
oxides, the barrier layer may also contain unavoidable impurities
and the like.
[0148] Here, from a point of view of having a superior diffusion
inhibition effect of a metal constituting the metal layer, superior
adhesion, and the like, it is desirable that the barrier layer be
composed primarily of an oxide of a metal contained in the metal
oxide layer.
[0149] More specifically, for example, when a TiO.sub.2 layer is
selected as the metal oxide layer, it is desirable that the barrier
layer be a titanium oxide layer composed primarily of an oxide of
Ti, which is the metal contained in the TiO.sub.2 layer.
[0150] Further, when the barrier layer is a titanium oxide layer,
the barrier layer may be a thin film layer formed as a titanium
oxide from the very beginning. The barrier layer may also be a thin
film layer formed by post-oxidizing a metal Ti layer, or a thin
film layer formed by post-oxidizing a partially oxidized titanium
oxide layer.
[0151] The barrier layer is composed mainly of a metal oxide, same
as the metal oxide layer. However, the barrier layer is configured
to have a thinner film thickness than the metal oxide layer. This
is because diffusion of the metal constituting the metal layer
occurs at an atomic level so that the necessity is low to thicken
to a film thickness required to ensure a sufficient refractive
index. Further, forming a thin layer reduces film formation cost,
and thus can contribute to reduction of the production cost of the
present film.
[0152] From a point of view of being likely to ensure barrier
capability and the like, it is desirable that the film thickness of
the barrier layer have a lower limit of preferably 1 nm or more,
more preferably 1.5 nm or more, and even more preferably 2 nm or
more. On the other hand, from a point of view of economic
efficiency and the like, it is desirable that the film thickness of
the barrier layer have an upper limit of preferably 15 nm or less,
more preferably 10 nm or less, and even more preferably 8 nm or
less.
[0153] When the barrier layer is composed mainly of a titanium
oxide, from a point of view of the barrier capability and the like,
it is desirable that an atomic mole ratio, Ti/O, of titanium with
respect to oxygen in the titanium oxide have a lower limit of
preferably 1.0/4.0 or more, more preferably 1.0/3.8 or more, even
more preferably 1.0/3.5 or more, even most preferably 1./0/3.0 or
more, and most preferably 1.0/2.8 or more.
[0154] When the barrier layer is composed mainly of a titanium
oxide, from a point of view of the visible light transparency and
the like, it is desirable that the atomic mole ratio, Ti/O, of
titanium with respect to oxygen in the titanium oxide have an upper
limit of preferably 1.0/0.5 or less, more preferably 1.0/0.7 or
less, even more preferably 1.0/1.0 or less, even more preferably
1.0/1.2 or less, and most preferably 1./0/1.5 or less.
[0155] The Ti/O ratio can be calculated from the composition of the
layer. As a composition analysis method of the layer, from a point
of view of allowing composition of an extremely thin thin film
layer to be relatively accurately analyzed, energy dispersive
fluorescent X-ray analysis (EDX) can be preferably used.
[0156] To explain about a specific composition analysis method,
first, by using an ultra thin sectioning method (microtome) and the
like, a test specimen is prepared having a thickness of 100 nm or
less in a cross sectional direction of the laminate structure
containing the layer to be analyzed. Next, the laminated structure
and location of the layer from the cross sectional direction are
confirmed using a transmission electron microscope (TEM). Next, an
electron beam is emitted from an electron gun of an EDX equipment
and is made incident to a vicinity of a thickness-wise central
region of the layer to be analyzed. Electrons made incident from a
surface of the test specimen penetrate to a certain depth and
generate various electron beams and X-rays. In this case, by
detecting and analyzing characteristic X-rays, constituent elements
of the layer can be analyzed.
[0157] In the present film, for the barrier layer, from a point of
view of allowing formation of a dense film, allowing formation of a
thin film layer having a uniform film thickness of about from
several nanometers to several tens of nanometers, and the like, a
gas phase method can be preferably used.
[0158] Examples of the gas phase method include, specifically, for
example, physical vapor deposition methods (PVD) such as a vacuum
deposition method, a sputtering method, an ion plating method, an
MBE method, a laser ablation method, and the like; chemical vapor
deposition methods (CVD) such as a thermal CVD method, a plasma CVD
method, and the like; and the like. As the gas phase method, the
sputtering method such as a DC magnetron sputtering method, an RF
magnetron sputtering method, and the like can be preferably used,
from a point of view that adhesion at a film interface is superior,
film thickness control is easy, and the like, as compared to a
vacuum deposition method and the like.
[0159] Each barrier layer contained in the laminate structure may
be formed by using any one of these gas phase methods, or, may also
be formed by using two or more of these gas phase methods.
[0160] The barrier layer may be formed using the above described
gas phase methods as a metal oxide layer from the very beginning.
Or, the barrier layer can also be formed by first forming a metal
layer or a partially oxidized metal oxide layer and then
post-oxidizing the metal layer or the partially oxidized metal
oxide layer. A partially oxidized metal oxide layer is a metal
oxide layer having room for further oxidation.
[0161] In the case where the barrier layer is formed as a metal
oxide layer from the very beginning, specifically, for example, the
thin film may be formed by further mixing a gas containing oxygen
as a reactive gas with an inert gas such as argon and neon as a
sputtering gas and allowing metal and oxygen to react (reactive
sputtering method). In the case where, for example, a titanium
oxide layer having the above-mentioned Ti/O ratio is obtained using
the reactive sputtering method, an optimal oxygen concentration in
the atmosphere (volume ratio of the oxygen-containing gas to the
inert gas) may be appropriately selected by considering the above
described film thickness range.
[0162] On the other hand, in the case where a metal layer or a
partially oxidized metal oxide layer is formed and later
post-oxidized, specifically, the above described laminate structure
may be formed on the transparent polymer film and thereafter the
metal layer or partially oxidized metal oxide layer in the laminate
structure may be post-oxidized. For the formation of the metal
layer, a sputtering method and the like may be used; for the
formation of the partially oxidized metal oxide layer, the above
described reactive sputtering method and the like may be used.
[0163] Examples of a post-oxidation method include heat treatment,
pressure treatment, chemical treatment, natural oxidation, and the
like. Among these post-oxidation methods, from a point of view of
being relatively simple and allowing post-oxidation to be reliably
performed and the like, the heat treatment is preferable. Examples
of the heat treatment include, for example, a method in which the
transparent polymer film having the above described laminate
structure is placed in a heating atmosphere such as a heating
furnace and the like, a warm water immersion method, a microwave
heating method, a method in which a metal layer, a partially
oxidized metal oxide layer, and the like in the laminate structure
are electrical-current heated, and the like. One method or a
combination of two or more of these methods may be performed.
[0164] It is desirable that heating conditions during the heat
treatment be selected from, specifically, for example, a heating
temperature within a range of preferably 30.degree. C.-60.degree.
C., more preferably 32.degree. C.-57.degree. C., and even more
preferably 35.degree. C.-55.degree. C., and a heating time of
preferably 5 days or more, more preferably 10 days or more, and
even more preferably 15 days or more, when placed in a heating
atmosphere. This is because of good post-oxidation effect, thermal
deformation and fusion bonding inhibition effects of the
transparent polymer film, and the like, when the heating conditions
are within the above ranges.
[0165] It is desirable that the heating atmosphere during the heat
treatment be an atmosphere containing oxygen and moisture such as
the air, a high oxygen atmosphere, a high humidity atmosphere, and
the like. From a point of view of manufacturability, cost
reduction, and the like, the air is particularly preferable.
[0166] In a case where the above described post-oxidized thin film
is contained in the laminate structure, during post-oxidation,
moisture and oxygen contained in the metal oxide layer are
consumed. Therefore, even when exposed to sunlight, the metal oxide
layer is unlikely to undergo a chemical reaction. Specifically, for
example, when a metal oxide layer is formed using a sol-gel method,
during post-oxidation, moisture and oxygen contained in the metal
oxide layer are consumed. Therefore, it is unlikely for a sol-gel
curing reaction, caused by sunlight, to occur between a starting
material (metal alkoxide and the like) of the sol-gel method
remained in the metal oxide layer and moisture (absorbed water and
the like), oxygen, and the like. Therefore, an internal stress
caused by a volume change due to cure shrinkage and the like can be
relaxed, interfacial debonding in the laminate structure is likely
inhibited, and durability against sunlight is likely improved.
[0167] It is desirable that the above described present film have a
visible light transmittance of 60% or more. This is because the
present film is useful as a film for applying to a window glass of
an architectural structure such as a building and a house, a window
glass of a vehicle such as an automobile, and the like. It is
desirable that the visible light transmittance be preferably 65% or
more and more preferably 70% or more.
[0168] The present film can be suitably used for transmission of
radio wave having a frequency of 100 MHz or more. Examples of
specific radio waves include radio wave of an ETC system (5.8 GHz),
radio wave of a mobile phone (800 MHz-2.2 GHz), and the like.
[0169] 2. Present Production Method
[0170] The present production method is a method capable of
suitably producing the present film described above.
[0171] 2.1 First Production Method
[0172] A first production method includes a lamination process and
a groove formation process.
[0173] The lamination process is a process forming the laminate
structure in which a metal oxide layer, which contains an organic
component, and a metal layer are laminated on at least one side of
a transparent polymer film. The lamination process varies depending
on the configuration of the laminate structure. However, basically,
each layer can be formed using an optimal method for the layer, and
the laminate structure can be formed by sequentially laminating
each layer. In the case where a barrier layer is formed using a
post-oxidation method, each layer is sequentially laminated in a
way including the layer before post-oxidation, and thereafter,
convert the layer into a barrier layer by post-oxidation.
[0174] In the lamination process, a transparent polymer film having
an easy adhesion layer formed on one side or both sides thereof can
be suitably used. In this case, it is desirable that the laminate
structure be formed on top of the easy adhesion layer. This is
because that, during the formation of the laminate structure,
cracks can be formed, and thus, the surface resistance of the film
is easily ensured.
[0175] The groove formation process is a process forming grooves
having a width of 30 .mu.m or less in the laminate structure formed
by the lamination process so that the overall surface resistance is
150.OMEGA./.quadrature. or more.
[0176] Examples of a groove formation method includes, for example,
(1) a method of applying a stress to generate cracks in the
laminate structure formed by the lamination process; (2) a method
of subjecting a surface of the laminate structure to laser
processing; (3) a method of stretching the film having the laminate
structure formed therein to generate cracks; and the like.
[0177] In the case of (1), for example, when the metal oxide layer
in the laminate structure contains as an organic component a
remaining component and the like of a starting material and the
like of a sol-gel method, the organic component is caused to
undergo a reaction, and a stress is generated in the laminate
structure by the reaction process, which causes cracks to form.
Such a method and the like can be used.
[0178] More specifically, for example, in an atmosphere containing
oxygen (O.sub.2), ozone (O.sub.3), moisture, and the like, by
supplying energy such as ultraviolet light, electron beam, heat,
and the like from the surface of the laminate structure, the
organic component is caused to undergo a reaction, and a stress is
generated in the laminate structure by the reaction process, which
can cause cracks to form.
[0179] The above groove formation process may be performed once or
two or more times. That is, the groove formation process may be
performed for a plurality of times so that the overall surface
resistance of the film is 150.OMEGA./.quadrature. or more. Further,
from a point of view of promoting the above-mentioned reaction, the
cracks may be formed under heating.
[0180] In the above method (1), when grooves are formed by cracks,
it is desirable that the outermost surface of the laminate
structure be a metal oxide layer containing as an organic component
a remaining component of a starting material of sol-gel method.
This is because a sol-gel reaction of a remaining component
contained in the outermost surface proceeds easily, cracks are
induced in the metal oxide layer by cure shrinkage, and, using
these cracks as base points, the cracks are easily propagated into
the laminate structure.
[0181] Processing conditions for the laser processing of the above
method (2) is not particularly limited as far as grooves of 30
.mu.m or less can be formed. Examples of the laser wavelength used
include, for example, a range of 0.1-10 .mu.m, and the like.
[0182] The film stretching in the above method (3) may any one of a
uniaxial stretching and a biaxial stretching. When the groove
formation is performed by film stretching, hardly visible cracks
can be relatively simply introduced into the laminate structure,
and a predetermined surface resistance can be ensured. In
particular, when the stretching is a biaxial stretching,
non-directional cracks are easily formed. Therefore, directionality
in the surface resistance is unlikely to appear, and a transparent
laminate film having superior uniformity in the surface resistance
can be obtained.
[0183] From a point of view of ensuring the surface resistance, it
is desirable that a tensile ratio during stretching have a lower
limit of preferably 0.5% or more, more preferably 1% or more, and
even more preferably 2% or more. On the other hand, from a point of
view of flatness of the film, heat resistance, ensuring optical
characteristics, and the like, it is desirable that the tensile
ratio during stretching have an upper limit of preferably 50% or
less, more preferably 40% or less, and even more preferably 30% or
less.
[0184] When performing the above described post-oxidation, the
post-oxidation may be performed before the grooves are formed or
after the groove are formed.
[0185] 2.2 Second Production Method
[0186] A second production method includes a lamination process.
However, the second production method is significantly different
from the first production method in that the second production
method does not include a groove formation process.
[0187] That is, the lamination process of the second production
method is a process in which a transparent polymer film having an
easy adhesion layer on at least one side thereof is prepared, and,
on top of the easy adhesion layer on the at least one side, a metal
oxide layer, which contains an organic component, and a metal
layer, are laminated to form a laminate structure.
[0188] When the laminate structure is formed on top of the easy
adhesion layer, a phenomenon is seen that cracks are easily formed
in the layers constituting the laminate structure during the
formation of the laminate structure. A detailed mechanism is
unknown. However, it is presumed that it is because crack formation
is promoted by a stress caused by shrinkage of the easy adhesion
layer due to the formation of the laminate structure, stress
concentration on protruding portions due to dispersed particles
such as silica particles, which are often contained in the easy
adhesion layer, surface roughness of the easy adhesion layer, and
the like. Regardless of the underlying mechanism, the cracks formed
during the formation of the laminate structure can be used as
grooves, thereby, the continuity of the metal layer constituting
the laminate structure can be broken in the lamination process.
Therefore, a groove formation process can be omitted.
[0189] In the lamination process, it is desirable that the prepared
transparent polymer film have the easy adhesion layer formed on
both sides thereof. This is because of advantages such as that,
when an easy adhesion layer also exists on a side of the film
opposite to the side on which the laminate structure is formed,
winding and feeding of the film become easy.
EMBODIMENTS
[0190] In the following, the present invention is explained in
detail using embodiments and comparative examples.
1. Preliminary Experiment
[0191] Four types of transparent laminate films and two types of
ITO films, having different surface resistances, were prepared. The
surfaces resistances of these six types of films were measured
using an eddy current meter (manufactured by DELCOM). Transmission
attenuation (shielding capability) at a frequency of 1 GHz was
measured using an electromagnetic wave shielding and
electromagnetic shielding properties testing equipment ("MA8602B"
manufactured by Anritsu Corporation) and a spectrum analyzer
("MS2661C" manufactured by Anritsu Corporation), according to a
method of the Kansai Electronic Industry Development Center (KEC).
FIG. 1 illustrates a relation between the surface resistance
(.OMEGA./.quadrature.) and the transmission attenuation (dB).
[0192] According to FIG. 1, in order to achieve a transmission
attenuation of 7 dB or less, required to allow 1/5 or more of radio
wave energy to pass through, an overall surface resistance of 150
(.OMEGA./.quadrature.) or more of the film is required. It is clear
that, when the surface resistance is less than 150
(.OMEGA./.quadrature.), the transmission attenuation increases so
that a degree of radio wave transparency necessary for practical
use cannot be obtained.
2. Experiment 1
[0193] 2.1 Preparation of Transparent Laminate Film (without
Grooves)
[0194] Transparent laminate films (without grooves) having a
three-layer laminate structure and a seven-layer laminate
structure, as outlined in the following, were prepared.
[0195] That is, the transparent laminate film having a three-layer
laminate structure (without grooves) has a laminate structure in
which the following layers are laminated in sequence on a surface
(PET surface) on a side opposite to an easy adhesion layer side of
a PET film: a TiO.sub.2 layer formed by a sol-gel method and
ultraviolet irradiation (first layer)|a layer formed by
post-oxidizing a metal Ti layer/an Ag--Cu alloy layer/a metal Ti
layer (second layer)|a TiO.sub.2 layer formed by a sol-gel method
and ultraviolet irradiation (third layer).
[0196] On the other hand, the transparent laminate film having a
seven-layer laminate structure (without grooves) has a laminate
structure in which the following layers are laminated in sequence
on a surface (PET surface) on a side opposite to an easy adhesion
layer side of a PET film: a TiO.sub.2 layer formed by a sol-gel
method and ultraviolet irradiation (first layer)|a layer formed by
post-oxidizing a metal Ti layer/an Ag--Cu alloy layer/a metal Ti
layer (second layer)|a TiO.sub.2 layer formed by a sol-gel method
and ultraviolet irradiation (third layer)|a layer formed by
post-oxidizing a metal Ti layer/an Ag--Cu alloy layer/a metal Ti
layer (fourth layer)|a TiO.sub.2 layer formed by a sol-gel method
and ultraviolet irradiation (fifth layer)|a layer formed by
post-oxidizing a metal Ti layer/an Ag--Cu alloy layer/a metal Ti
layer (sixth layer)|a TiO.sub.2 layer formed by a sol-gel method
and ultraviolet irradiation (seventh layer).
[0197] In the above, the post-oxidized metal Ti layers correspond
to barrier layers. The barrier layers, as thin films attached to
the alloy layers, are included in the alloy layers for laminating
layer number counting. The post-oxidation, specifically, is thermal
oxidation.
[0198] In the following, specific preparation steps of the
transparent laminate film (without grooves) are explained.
[0199] (Preparation of Coating Liquid)
[0200] First, a coating liquid used in forming a TiO.sub.2 thin
film by a sol-gel method was prepared. That is, the coating liquid
was prepared by combining a tetra-n-butoxy titanium tetramer ("B4",
manufactured by Nippon Soda Co., Ltd.) as a titanium alkoxide and
acetylacetone as an additive forming a ultraviolet light absorbing
chelate with a mixed solution of n-butanol and isopropyl alcohol,
and mixing the combination for 10 minutes using a stirrer. In this
case, combination percentages of tetra-n-butoxy titanium
tetramer/acetylacetone/n-butanol/isopropyl alcohol were
respectively 6.75% by mass/3.38% by mass/59.87% by mass/30.00% by
mass.
[0201] (Lamination of each Layer)
[0202] As the transparent polymer film, a polyethylene
terephthalate film having a thickness of 50 .mu.m and having an
easy adhesion layer formed on one side thereof ("COSMOSHINE
(registered trademark) A4100" manufactured by Toyobo Co., Ltd.)
(referred to as "PET film" in the following) was used. On a side
(the PET side) opposite to the easy adhesion layer side of the PET
film, a TiO.sub.2 layer as a first layer was formed by the
following steps.
[0203] That is, the coating liquid was continuously coated on the
PET side of the PET film using a micro gravure coater with gravure
rolls each having a predetermined groove volume. Next, using an
inline drying furnace, the coated film was dried for 80 seconds at
a temperature of 100.degree. C., and a precursor layer of a
TiO.sub.2 layer was formed. Next, using an inline ultraviolet light
irradiation equipment [a high pressure mercury lamp (160 W/cm)],
the precursor layer was continuously irradiated with ultraviolet
light for 1.5 seconds at a same line speed as during coating. By
doing this, a TiO.sub.2 layer (first layer) by a sol-gel method
using ultraviolet light energy during sol-gel curing (which may be
sometimes referred to as "sol-gel+UV" in abbreviation in the
following) was formed on the PET film.
[0204] Next, on top of the first layer, thin films constituting the
second layer were formed.
[0205] That is, a lower side metal Ti layer was formed on top of
the TiO.sub.2 layer of the first layer by sputtering using a DC
magnetron sputter equipment. Next, an Ag--Cu alloy layer was formed
on top of the lower side metal Ti layer by sputtering. Next, an
upper side metal Ti layer was formed on top of the Ag--Cu alloy
layer by sputtering.
[0206] In this case, film formation conditions for the upper and
lower side metal Ti layers were as follows: Ti target (purity 4N);
ultimate vacuum pressure: 5.times.10.sup.-6 (Torr); inert gas: Ar;
gas pressure: 2.5.times.10.sup.-3 (Torr); input power: 1.5 (kW);
and film formation time: 1.1 seconds.
[0207] Film formation conditions for the Ag--Cu alloy thin film
were as follows: Ag--Cu alloy target (Cu content: 4% by atom);
ultimate vacuum pressure: 5.times.10.sup.-6 (Torr); inert gas: Ar;
gas pressure: 2.5.times.10.sup.-3 (Torr); input power: 1.5 (kW);
and film formation time: 1.1 seconds.
[0208] Next, as the third layer, the TiO.sub.2 layer by
"sol-gel+UV" was formed on top of the second layer. Here, a
predetermined film thickness was obtained by performing twice the
film formation steps according to the first layer.
[0209] Thereafter, the transparent laminate film obtained via the
above lamination process was subjected to a heat treatment in a
heating furnace for 300 hours at a temperature of 40.degree. C. to
post-oxidize the metal Ti layer/Ag--Cu alloy layer/metal Ti layer
(the second layer) contained in the laminate structure.
[0210] Thus, the transparent laminate film having the three-layer
laminate structure (without grooves) was prepared. The transparent
laminate film having the seven-layer laminate structure (without
grooves) was prepared by performing the following steps, continued
from the step after the third layer was laminated (without the
post-oxidation step after the formation of the third layer) in the
preparation of the transparent laminate film having the three-layer
laminate structure (without grooves). That is, as the fourth layer,
on top of the third layer, thin films constituting the fourth layer
were formed. Here, film formation steps according to the second
layer were performed.
[0211] However, the above described film formation conditions
during the formation of the Ag--Cu alloy thin film were modified as
follows: Ag--Cu alloy target (Cu content: 4% by atom); ultimate
vacuum pressure: 5.times.10.sup.-6 (Torr); inert gas: Ar; gas
pressure: 2.5.times.10.sup.-3 (Torr); input power: 1.8 (kW); and
film formation time: 1.1 seconds, and thereby, the film thickness
was changed.
[0212] Next, as the fifth layer, on top of the fourth layer, a
TiO.sub.2 layer by "sol-gel+UV" having the same configuration as
the third layer was formed.
[0213] Next, as the sixth layer, on top of the fifth layer, thin
films having the same configuration as those of the second layer
were formed.
[0214] Next, as the seventh layer, on top of the sixth layer, a
TiO.sub.2 layer by "sol-gel+UV" was formed. Here, a predetermined
film thickness was obtained by performing once the film formation
steps according to the first layer.
[0215] Thereafter, the transparent laminate film obtained via the
above lamination process was subjected to a heat treatment in a
heating furnace for 300 hours at a temperature of 40.degree. C. to
post-oxidize the metal Ti layer/Ag--Cu alloy layer/metal Ti layer
(the second, fourth, and sixth layers) contained in the laminate
structure.
[0216] Thus, the transparent laminate film having the seven-layer
laminate structure (without grooves) was prepared.
[0217] Refractive indices of the TiO.sub.2 layers (for a
measurement wavelength of 633 nm) were measured using a FilmTek
3000 (manufactured by Scientific Computing International).
[0218] Contents of the organic components contained in the
TiO.sub.2 layers were measured using an X-ray photoelectron
spectroscopy (XPS).
[0219] With respect to the titanium oxide thin films formed by
post-oxidizing the metal Ti layers, EDX analysis was performed, and
Ti/O ratios were obtained as follows.
[0220] That is, a test specimen having a thickness of 100 nm or
less in a cross sectional direction of the laminated structure
containing the titanium oxide layer (barrier layer) to be analyzed
was prepared by cutting the transparent laminate film using a
microtome ("ultrome V2088" manufactured by LKB). A cross section of
the prepared test specimen was confirmed using a field emission
electron microscopy (HRTEM) ("JEM2001F" manufactured by JEOL Ltd.).
Next, by using an EDX equipment (which has a spectral resolution of
133 eV or less) ("JED-2300T" manufactured by JEOL Ltd.), an
electron beam was emitted from an electron gun of the EDX equipment
and was made incident to a vicinity of a thickness-wise central
region of the titanium oxide layer (barrier layer) to be analyzed.
Analysis of constituent elements of the titanium oxide layer
(barrier layer) was performed by detecting and analyzing generated
characteristic X-rays.
[0221] Content of the secondary element Cu contained in the alloy
layers was obtained as follows. That is, under the film formation
conditions, a test specimen was separately prepared by forming an
Ag--Cu alloy layer on a glass substrate. The test specimen was
immersed in a solution containing 6% of HNO.sub.3. After performing
elution by ultrasound for 20 minutes, the obtained sample solution
was used to perform a measurement using a concentration method of
an ICP analysis method.
[0222] Thickness of each of the layers was measured by
cross-sectional observation of the test specimen using the field
emission electron microscopy (HRTEM) ("JEM2001F" manufactured by
JEOL Ltd.).
[0223] Table 1 illustrates detailed lamination configuration of the
transparent laminate films having the three-layer laminate
structures (without grooves), and Table 2 illustrates detailed
lamination configuration of the transparent laminate films having
the seven-layer laminate structures (without grooves).
TABLE-US-00001 TABLE 1 Comparative Embodiments examples 1, 3, 5, 6
1, 3, 5 Thin first Metal oxide layer (sol-gel + UV) -- TiO.sub.2
TiO.sub.2 film layer layer Film thickness (nm) 22 22 configuration
Refractive index -- 1.85 1.85 (before Organic component content (%)
15 15 groove second layer Barrier layer Post-oxidation Titanium
oxide Titanium oxide formation) Film thickness (nm) 2 2 Ti/O ratio
-- 1.0/1.8-1.0/1.6 1.0/1.8-1.0/1.6 Metal layer -- Ag--Cu Ag--Cu
Film thickness (nm) 9 9 Secondary element content (% by atom) Cu: 4
Cu: 4 Barrier layer Post-oxidation Titanium oxide Titanium oxide
Film thickness (nm) 2 2 Ti/O ratio -- 1.0/1.8-1.0/1.6
1.0/1.8-1.0/1.6 third Metal oxide layer (sol-gel + UV) -- TiO.sub.2
TiO.sub.2 layer Film thickness (nm) 34 34 Refractive index -- 1.85
1.85 Organic component content (%) 15 15 Order of a laminating
layer is counted from the film side. A barrier layer, as a thin
film layer attached to a metal layer, is included in the metal
layer for laminating layer number counting. Film thickness is
physical film thickness.
TABLE-US-00002 TABLE 2 Comparative Embodiments examples 2, 4, 7, 8
2, 4, 6 Thin first Metal oxide layer (sol-gel + UV) -- TiO.sub.2
TiO.sub.2 film layer layer Film thickness (nm) 22 22 configuration
Refractive index -- 1.85 1.85 (before Organic component content (%)
15 15 groove second & Barrier layer Post-oxidation Titanium
oxide Titanium oxide formation) sixth layers Film thickness (nm) 2
2 Ti/O ratio -- 1.0/1.8-1.0/1.6 1.0/1.8-1.0/1.6 Metal layer --
Ag--Cu Ag--Cu Film thickness (nm) 9 9 Secondary element content (%
by atom) Cu: 4 Cu: 4 Barrier layer Post-oxidation Titanium oxide
Titanium oxide Film thickness (nm) 2 2 Ti/O ratio --
1.0/1.8-1.0/1.6 1.0/1.8-1.0/1.6 third & Metal oxide layer
(sol-gel + UV) -- TiO.sub.2 TiO.sub.2 fifth Film thickness (nm) 68
68 layers Refractive index -- 1.85 1.85 Organic component content
(%) 15 15 fourth layer Barrier layer Post-oxidation Titanium oxide
Titanium oxide Film thickness (nm) 2 2 Ti/O ratio --
1.0/1.8-1.0/1.6 1.0/1.8-1.0/1.6 Metal layer -- Ag--Cu Ag--Cu Film
thickness (nm) 11 11 Secondary element content (% by atom) Cu: 4
Cu: 4 Barrier layer Post-oxidation Titanium oxide Titanium oxide
Film thickness (nm) 2 2 Ti/O ratio -- 1.0/1.8-1.0/1.6
1.0/1.8-1.0/1.6 seventh Metal oxide thin film (sol-gel + --
TiO.sub.2 TiO.sub.2 layer UV) Film thickness (nm) 34 34 Refractive
index -- 1.85 1.85 Organic component content (%) 15 15 Order of a
laminating layer is counted from the film side. A barrier layer, as
a thin film layer attached to a metal layer, is included in the
metal layer for laminating layer number counting. Film thickness is
physical film thickness.
[0224] 2.2 Preparation of Transparent Laminate Film (with
Grooves)
(1) Transparent Laminate Film Having Grooves Formed by Cracks
(Ozone Ashing)
[0225] The above prepared transparent laminate film having the
three-layer laminate structure (without grooves) and transparent
laminate film having the seven-layer laminate structure (without
grooves) were prepared.
[0226] Next, surfaces of the laminate structures of the transparent
laminate films (without grooves) were ozone ashed in a mixture of
oxygen (O.sub.2) and ozone (O.sub.3) using a surface treatment
apparatus (an "ozone ashing equipment" manufactured by Surf Clean
Co.).
[0227] In this case, a supplying oxygen (O.sub.2) flow rate was 3
L/minute, and ozone (O.sub.3) concentration was 50 ppm. A stage
speed of the surface treatment apparatus was 0.3 m/minute. Heating
was performed for promoting sol-gel reaction of a remaining
component of a starting material of the sol-gel method, contained
in the TiO.sub.2 layers (in particular, the outermost layer).
Heating was performed using an infrared heater equipped in the
surface treatment apparatus (heater set temperature:
160.quadrature.).
[0228] The above ozone ashing processing was performed five times
with respect to the transparent laminate film having the
three-layer laminate structure (without grooves), which was used as
a transparent laminate film according to an embodiment 1. The above
ozone ashing processing was performed five times with respect to
the transparent laminate film having the seven-layer laminate
structure (without grooves), which was then used as a transparent
laminate film according to an embodiment 2.
[0229] On the other hand, the transparent laminate film having the
three-layer laminate structure (without grooves) was used as a
transparent laminate film according to a comparative example 1. The
transparent laminate film having the seven-layer laminate structure
(without grooves) was used as a transparent laminate film according
to a comparative example 2. The above ozone ashing processing was
performed three times with respect to the transparent laminate film
having the three-layer laminate structure (without grooves), which
was then used as a transparent laminate film according to a
comparative example 3. The above ozone ashing processing was
performed three times with respect to the transparent laminate film
having the seven-layer laminate structure (without grooves), which
was then used as a transparent laminate film according to a
comparative example 4.
(2) Transparent Laminate Film Having Grooves Formed by Laser
Processing
[0230] The above prepared transparent laminate film having the
three-layer laminate structure (without grooves) and transparent
laminate film having the seven-layer laminate structure (without
grooves) were prepared.
[0231] Next, surfaces of the laminate structures of the transparent
laminate film (without grooves) were laser processed using a laser
processing apparatus (LD pumped Nd:YVO4 laser of a wavelength
.lamda.=532 nm, manufactured by Takei Electric Industries Co.,
Ltd.). FIG. 2 illustrates shapes formed by the laser processing.
FIG. 2 shows diagrams of the transparent laminate films F viewed
from the laminate structure surface side: (a) illustrates slit-like
grooves having a groove width W=10 .mu.m and a groove pitch P=2 mm;
and (b) illustrates lattice-like grooves having a groove width W=10
.mu.m and a groove pitch P=2 mm. Laser processing conditions, for
processing any of the shapes, were as follows: power: 0.1 W;
frequency: 40 kHz; and processing speed: 200 mm/second.
[0232] The transparent laminate film having the three-layer
laminate structure (without grooves) was used to have lattice-like
grooves formed in the laminate structure so as to obtain a surface
resistance of 150.OMEGA./.quadrature. or more, and was then used as
a transparent laminate film according to an embodiment 3. The
transparent laminate film having the seven-layer laminate structure
(without grooves) was used to have lattice-like grooves formed in
the laminate structure so as to obtain a surface resistance of
150.OMEGA./.quadrature. or more, and was then used as a transparent
laminate film according to an embodiment 4.
[0233] On the other hand, the transparent laminate film having the
three-layer laminate structure (without grooves) was used to have
slit-like grooves formed in the laminate structure so as to obtain
a surface resistance of less than 150.OMEGA./.quadrature., and was
then used as a transparent laminate film according to a comparative
example 5. The transparent laminate film having the seven-layer
laminate structure (without grooves) was used to have slit-like
grooves formed in the laminate structure so as to obtain a surface
resistance of less than 150.OMEGA./.quadrature., and was then used
as a transparent laminate film according to a comparative example
6.
(3) Transparent Laminate Film Having Grooves (Stretching) Formed by
Cracks
[0234] The above prepared transparent laminate film having the
three-layer laminate structure (without grooves) and transparent
laminate film having the seven-layer laminate structure (without
grooves) were prepared. Sizes of the prepared transparent laminate
films are: length: 200 mm, and width: 200 mm.
[0235] Next, uniaxial stretching was performed with respect to each
sample using a uniaxial stretching apparatus ("STA-1225"
manufactured by ORIENTEC Co., Ltd.) to introduce cracks as grooves.
Biaxial stretching was performed with respect to each sample using
a biaxial stretching apparatus ("2AT-500" manufactured by Shimadzu
Corporation) to introduce cracks as grooves.
[0236] In this case, conditions of the uniaxial stretching were:
tensile direction:longitudinal direction, and tensile ratio:15%.
Conditions of the biaxial stretching were: tensile
direction:longitudinal direction and width-wise direction, and
tensile ratio:3%.
[0237] The above uniaxial stretching was performed with respect to
the transparent laminate film having the three-layer laminate
structure (without grooves), which was then used as a transparent
laminate film according to an embodiment 5. The above biaxial
stretching was performed with respect to the transparent laminate
film having the three-layer laminate structure (without grooves),
which was then used as a transparent laminate film according to an
embodiment 6. The above uniaxial stretching was performed with
respect to the transparent laminate film having the seven-layer
laminate structure (without grooves), which was then used as a
transparent laminate film according to an embodiment 7. The above
biaxial stretching was performed with respect to the transparent
laminate film having the seven-layer laminate structure (without
grooves), which was then used as a transparent laminate film
according to an embodiment 8.
3. Experiment 2
[0238] 3.1 Preparation of Transparent Laminate Film (with
Grooves)
[0239] A polyethylene terephthalate film of a thickness of 38 .mu.m
having an easy adhesion layer formed on both sides thereof
("COSMOSHINE (registered trademark) A4300" manufactured by Toyobo
Co., Ltd.) (PET film) was prepared as the transparent polymer film,
and a thin film having a three-layer laminate structure or a
seven-layer laminate structure was formed on one easy adhesion
layer side of this PET film. Except this point, a transparent
laminate film having a three-layer laminate structure (with
grooves) (embodiment 9) and a transparent laminate film having a
seven-layer laminate structure (with grooves) (embodiment 10) were
prepared in the same way as for the preparation of the transparent
laminate film (without grooves) in the experiment 1, as outlined in
the following.
[0240] That is, the transparent laminate film having a three-layer
laminate structure (with grooves) (embodiment 9) has a laminate
structure in which the following layers are laminated in sequence
on top of the easy adhesion layer of the PET film: a TiO.sub.2
layer formed by a sol-gel method and ultraviolet irradiation (first
layer)|a layer formed by post-oxidizing a metal Ti layer/an Ag--Cu
alloy layer/a metal Ti layer (second layer)|a TiO.sub.2 layer
formed by a sol-gel method and ultraviolet irradiation (third
layer).
[0241] On the other hand, the transparent laminate film having a
seven-layer laminate structure (with grooves) (embodiment 10) has
laminate structure in which the following layers are laminated in
sequence on top of the easy adhesion layer of the PET film: a
TiO.sub.2 layer formed by a sol-gel method and ultraviolet
irradiation (first layer)|a layer formed by post-oxidizing a metal
Ti layer/an Ag--Cu alloy layer/a metal Ti layer (second layer)|a
TiO.sub.2 layer formed by a sol-gel method and ultraviolet
irradiation (third layer)|a layer formed by post-oxidizing a metal
Ti layer/an Ag--Cu alloy layer/a metal Ti layer (fourth layer)|a
TiO.sub.2 layer formed by a sol-gel method and ultraviolet
irradiation (fifth layer)|a layer formed by post-oxidizing a metal
Ti layer/an Ag--Cu alloy layer/a metal Ti layer (sixth layer)|a
TiO.sub.2 layer formed by a sol-gel method and ultraviolet
irradiation (seventh layer).
[0242] In the above, the post-oxidized metal Ti layers correspond
to barrier layers. The barrier layers, as thin films attached to
the alloy layers, are included in the alloy layers for laminating
layer number counting. The post-oxidation, specifically, is thermal
oxidation.
[0243] Here, the preparation of the transparent laminate film (with
grooves) is significantly different as compared with the
preparation of the transparent laminate film (without grooves) in
the experiment 1 in that the laminate structure is formed on top of
the adhesion layer of the PET film. When the laminate structure is
formed on top of the easy adhesion layer, cracks are formed in the
metal layers constituting the laminate structure during the
formation of the laminate structure. Therefore, by using these
cracks as grooves, without going through the groove formation
process performed in the experiment 1, the continuity of the metal
layers constituting the laminate structure can be broken, and
surface resistance can be increased.
[0244] 3.2 Preparation of Transparent Laminate Film (without
Grooves)
[0245] A polyethylene terephthalate film of a thickness of 38 .mu.m
having an easy adhesion layer formed on one side thereof
("COSMOSHINE (registered trademark) A4100" manufactured by Toyobo
Co., Ltd.) (PET film) was prepared as the transparent polymer film,
and a thin film having a three-layer laminate structure or a
seven-layer laminate structure was formed on a surface (PET
surface) on a side opposite to the easy adhesion layer side of this
PET film. Except this point, a transparent laminate film having a
three-layer laminate structure (without grooves) (comparative
example 7) and a transparent laminate film having a seven-layer
laminate structure (without grooves) (comparative example 8) were
prepared in the same way as for the preparation of the transparent
laminate film (without grooves) in the experiment 1, as outlined in
the following.
[0246] That is, the transparent laminate film having a three-layer
laminate structure (without grooves) (comparative example 7) has a
laminate structure in which the following layers are laminated in
sequence on a surface (PET surface) on a side opposite to the easy
adhesion layer side of the PET film: a TiO.sub.2 layer formed by a
sol-gel method and ultraviolet irradiation (first layer)|a layer
formed by post-oxidizing a metal Ti layer/an Ag--Cu alloy layer/a
metal Ti layer (second layer)|a TiO.sub.2 layer formed by a sol-gel
method and ultraviolet irradiation (third layer).
[0247] On the other hand, the transparent laminate film having a
seven-layer laminate structure (without grooves) (comparative
example 8) has laminate structure in which the following layers are
laminated in sequence on a surface (PET surface) on the side
opposite to the easy adhesion layer side of the PET film: a
TiO.sub.2 layer formed by a sol-gel method and ultraviolet
irradiation (first layer)|a layer formed by post-oxidizing a metal
Ti layer/an Ag--Cu alloy layer/a metal Ti layer (second layer)|a
TiO.sub.2 layer formed by a sol-gel method and ultraviolet
irradiation (third layer)|a layer formed by post-oxidizing a metal
Ti layer/an Ag--Cu alloy layer/a metal Ti layer (fourth layer)|a
TiO.sub.2 layer formed by a sol-gel method and ultraviolet
irradiation (fifth layer)|a layer formed by post-oxidizing a metal
Ti layer/an Ag--Cu alloy layer/a metal Ti layer (sixth layer)|a
TiO.sub.2 layer formed by a sol-gel method and ultraviolet
irradiation (seventh layer).
[0248] In the above, post-oxidized metal Ti layers correspond to
barrier layers. The barrier layers, as thin films attached to the
alloy layers, are included in the alloy layers for laminating layer
number counting. The post-oxidation, specifically, is thermal
oxidation.
[0249] Table 3 illustrates detailed lamination configurations of
transparent laminate films having the three-layer laminate
structures (with grooves and without grooves), and Table 4
illustrates detailed lamination configurations of transparent
laminate film having the seven-layer laminate structures (with
grooves and without grooves).
TABLE-US-00003 TABLE 3 Comparative Embodiment 9 Example 7 Film
Transparent polymer film -- PET PET Film thickness (.mu.m) 38 38
Thin film layer formation side Easy adhesion layer Opposite side
(PET side) of easy adhesion layer Thin first Metal oxide layer
(sol-gel + UV) -- TiO.sub.2 TiO.sub.2 film layer layer Film
thickness (nm) 22 22 configuration Refractive index -- 1.85 1.85
(grooves Organic Component content (%) 15 15 are formed second
layer Barrier layer Post-oxidation Titanium oxide Titanium oxide
during Film thickness (nm) 2 2 lamination Ti/O ratio --
1.0/1.8-1.0/1.6 1.0/1.8-1.0/1.6 for Metal layer -- Ag--Cu Ag--Cu
embodiment) Film thickness (nm) 9 9 Secondary element content (% by
atom) Cu: 4 Cu: 4 Barrier layer Post-oxidation Titanium oxide
Titanium oxide Film thickness (nm) 2 2 Ti/O ratio --
1.0/1.8-1.0/1.6 1.0/1.8-1.0/1.6 third Metal oxide layer (sol-gel +
UV) -- TiO.sub.2 TiO.sub.2 layer Film thickness (nm) 34 34
Refractive index -- 1.85 1.85 Organic component content (%) 15 15
Grooves existence Yes (Cracks) No Order of a laminating layer is
counted from the film side. A barrier layer, as a thin film layer
attached to a metal layer, is included in the metal layer for
laminating layer number counting. Film thickness is physical film
thickness.
TABLE-US-00004 TABLE 4 Comparative Embodiment 10 Example 8 Film
Transparent polymer film -- PET PET Film thickness (.mu.m) 38 38
Thin film layer formation side Easy adhesion layer Opposite side
(PET side) of easy adhesion layer Thin first Metal oxide layer
(sol-gel + UV) -- TiO.sub.2 TiO.sub.2 film layer layer Film
thickness (nm) 22 22 configuration Refractive index -- 1.85 1.85
(grooves Organic component content (%) 15 15 are formed second,
Barrier layer Post-oxidation Titanium oxide Titanium oxide during
sixth Film thickness (nm) 2 2 lamination layers Ti/O ratio --
1.0/1.8-1.0/1.6 1.0/1.8-1.0/1.6 for Metal layer -- Ag--Cu Ag--Cu
embodiment) Film thickness (nm) 9 9 Secondary element content (% by
atom) Cu: 4 Cu: 4 Barrier layer Post-oxidation Titanium oxide
Titanium oxide Film thickness (nm) 2 2 Ti/O ratio --
1.0/1.8-1.0/1.6 1.0/1.8-1.0/1.6 third, Metal oxide layer (sol-gel +
UV) -- TiO.sub.2 TiO.sub.2 fifth Film thickness (nm) 68 68 layers
Refractive index -- 1.85 1.85 Organic component content (%) 15 15
fourth layer Barrier layer Post-oxidation Titanium oxide Titanium
oxide Film thickness (nm) 2 2 Ti/O ratio -- 1.0/1.8-1.0/1.6
1.0/1.8-1.0/1.6 Metal layer -- Ag--Cu Ag--Cu Film thickness (nm) 11
11 Secondary element content (% by atom) Cu: 4 Cu: 4 Barrier layer
Post-oxidation Titanium oxide Titanium oxide Film thickness (nm) 2
2 Ti/O ratio -- 1.0/1.8-1.0/1.6 1.0/1.8-1.0/1.6 seventh Metal oxide
layer (sol-gel + UV) -- TiO.sub.2 TiO.sub.2 layer Film thickness
(nm) 34 34 Refractive index -- 1.85 1.85 Organic component content
(%) 15 15 Grooves existence Yes (Cracks) No Order of a laminating
layer is counted from the film side. A barrier layer, as a thin
film layer attached to a metal layer, is included in the metal
layer for laminating layer number counting. Film thickness is
physical film thickness.
[0250] 4. Evaluation of Transparent Laminate Films
[0251] 4.1 Optical Characteristics
[0252] With respect to each of the prepared transparent laminated
films, the following optical characteristics were measured. A
measurement sample used for a measurement was prepared by pasting
an acryl adhesive sheet having a thickness of 25 .mu.m ("CS9621"
manufactured by Nitto Denko Corporation) on a thin film laminating
layer surface of the transparent laminate film, and pasting an
adhesive layer of the adhesive sheet on one side of a float glass
having a thickness of 3 mm. Measurement light was made incident
from a glass surface side during evaluation of optical
characteristics.
[0253] (Visible Light Transmittance and Visible Light
Reflectance)
[0254] Transmission spectrum in a wavelength range of 300-1000 nm
was measured using a spectral photometer ("UV 3100" manufactured by
Shimadzu Corporation) in accordance with JIS A5759, and visible
light transmittance and visible light reflectance were obtained by
calculation.
[0255] (Solar Radiation Transmittance)
[0256] Transmission spectrum in a wavelength range of 300-2500 nm
was measured using a spectral photometer ("UV 3100" manufactured by
Shimadzu Corporation) in accordance with JIS A5759, and solar
radiation transmittance was obtained by calculation.
[0257] 4.2 Radio Wave Transparency
[0258] Transmission attenuation at a frequency of 1 GHz was
measured using an electromagnetic wave shielding and
electromagnetic shielding properties testing equipment ("MA8602B"
manufactured by Anritsu Corporation) and a spectrum analyzer
("MS2661C" manufactured by Anritsu Corporation), according to a
method of the Kansai Electronic Industry Development Center
(KEC).
[0259] 4.3 Appearance
[0260] The thin film layer formation side of the transparent
laminate film was applied to a window glass using a method of wet
application. Whether the grooves are visible was visually confirmed
from a distance of 30 cm. A case where the grooves are not visible
was considered as having a good appearance; and a case where the
grooves are visible was considered as having a poor appearance.
[0261] Results of the measurements with respect to each of the
transparent laminate films are summarized in Tables 5-8.
TABLE-US-00005 TABLE 5 three-layer laminate structure seven-layer
laminate structure Comparative Comparative Comparative Comparative
Embodiment 1 example 1 example 3 Embodiment 2 example 2 example 4
Grooves Formation method -- Ozone ashing -- Ozone ashing Ozone
ashing -- Ozone ashing 5 times 3 times 5 times 3 times Shape --
Cracks -- Cracks Cracks -- Cracks Surface resistance
(.OMEGA./.quadrature.) 480 16 47 476 4 12 Optical characteristics
Visible light transmittance (%) 88 88 87 70 72 70 Visible light
reflectance (%) 7 6 6 8 8 8 Solar radiation (%) 63 62 62 43 41 42
transmittance Radio wave transparency Transmission attenuation (dB)
1 24 15 1 34 18 (frequency 1.0 GHz) Appearance Good Good Good Good
Good Good
TABLE-US-00006 TABLE 6 three-layer laminate structure seven-layer
laminate structure Comparative Comparative Comparative Comparative
Embodiment 3 example 1 example 5 Embodiment 4 example 2 example 6
Grooves Formation method -- Laser -- Laser Laser -- Laser
processing processing processing processing Shape Groove 10 .mu.m
-- 10 .mu.m 10 .mu.m -- 10 .mu.m width Groove 2 mm -- 2 mm 2 mm --
2 mm pitch -- Angular -- Slit like Angular -- Slit like lattice
like lattice like Surface resistance (.OMEGA./.quadrature.) 400 16
85 385 4 80 Optical characteristics Visible light transmittance (%)
87 88 88 72 72 71 Visible light reflectance (%) 7 6 6 8 8 7 Solar
radiation (%) 62 62 63 41 41 40 transmittance Radio wave
transparency Transmission attenuation (dB) 1 24 13 1 34 10
(frequency 1.0 GHz) Appearance Good Good Good Good Good Good
TABLE-US-00007 TABLE 7 three-layer laminate structure seven-layer
laminate structure Comparative Comparative Embodiment 5 Embodiment
6 example 1 Embodiment 7 Embodiment 8 example 2 Grooves Formation
method -- Uniaxially Biaxially -- Uniaxially Biaxially --
stretching stretching stretching stretching 15% 3% .times. 3% 15%
3% .times. 3% Shape -- Cracks Cracks -- Cracks Cracks -- Surface
resistance (.OMEGA./.quadrature.) 500 or more 500 or more 16 333
303 4 Optical characteristics Visible light transmittance (%) 79 79
79 70 70 70 Visible light reflectance (%) 10 10 10 8 8 8 Solar
radiation (%) 60 61 59 44 45 43 transmittance Radio wave
transparency Transmission attenuation (dB) 1 1 24 1 3 30 (frequency
1.0 GHz) Appearance Good Good Good Good Good Good
TABLE-US-00008 TABLE 8 three-layer seven-layer laminate structure
laminate structure Comparative Embodiment Comparative Embodiment 9
example 7 10 example 8 Grooves Shape -- Cracks -- Cracks -- Surface
resistance (.OMEGA./.quadrature.) 500 or more 16 220 4 Optical
characteristics Visible light transmittance (%) 79 79 70 70 Visible
light reflectance (%) 10 10 8 8 Solar radiation (%) 59 59 43 43
transmittance Radio wave transparency Transmission attenuation (dB)
1 24 3 30 (frequency 1.0 GHz) Appearance Good Good Good Good
[0262] According to Table 5, the following is clear. That is, for
the transparent laminate films according to the comparative
examples 1 and 2, grooves due to cracks are not formed in the
laminate structures. Therefore, the metal layers in the laminate
structures are continuous, conductivity is high, and it is
difficult to achieve an overall surface resistance of
150.OMEGA./.quadrature. or more for the films. For this reason, the
transmission attenuation becomes large, and radio wave transparency
is poor.
[0263] For the transparent laminate films according to the
comparative examples 3 and 4, by performing ozone ashing with
respect to the surfaces of the laminate structures, remaining
components of starting materials of the sol-gel method contained in
the TiO.sub.2 layers (in particular, the outermost layers) are
further sol-gel reacted. However, insufficient energy was applied
to the laminate structures. Therefore, as FIG. 3 illustrates, there
are not enough number of cracks formed to achieve an overall
surface resistance of 150.OMEGA./.quadrature. or more for the
films. For this reason, although the transmission attenuation is
reduced as compared to the transparent laminate films according to
the comparative examples 1 and 2, the transmission attenuation is
still large, and the radio wave transparency is still poor.
[0264] In contrast, for the transparent laminate films according to
the embodiments 1 and 2, as FIG. 4 illustrates, there are numerous
cracks having a width of about 2-3 .mu.m formed in the laminate
structures. Due to the cracks introduced into the laminate
structures, the overall surface resistances of the films are
150.OMEGA./.quadrature. or more. That is, the metal layers in the
laminate structures are broken due to the cracks so that the
overall surface resistances of the films become
150.OMEGA./.quadrature. or more. Therefore, the films have good
radio wave transparency. In addition, because there are numerous
cracks, directionality in the surface resistance is unlikely to
appear so that the films also have superior uniformity in the
surface resistance.
[0265] Further, because the width of the grooves is 30 .mu.m or
less, the grooves are hardly visible to human eyes when used and
thus the films have a good appearance. In the above laminate
structures, the metal oxide layers such as the TiO.sub.2 layers and
the metal layers such as the Ag--Cu alloy layers and the like are
laminated. Therefore, good visible light transparency and solar
radiation shielding capability can be achieved. Reduction in
visible light transparency and solar radiation shielding capability
due to the introduction of the cracks is hardly seen.
[0266] According to Table 6, the following is clear. That is, for
the transparent laminate films according to the comparative
examples 1 and 2, grooves due to laser processing are not formed in
the laminate structures. Therefore, the metal layers in the
laminate structures are continuous, conductivity is high, and it is
difficult to achieve an overall surface resistance of
150.OMEGA./.quadrature. or more for the films. For this reason, the
transmission attenuation becomes large, and radio wave transparency
is poor.
[0267] For the transparent laminate films according to the
comparative examples 5 and 6, grooves are formed in the laminate
structures by subjecting the surfaces of the laminate structures to
laser processing. However, the number of grooves formed is not
sufficient. Therefore, the overall surface resistances of the films
are less than 150.OMEGA./.quadrature.. For this reason, although
the transmission attenuation is reduced as compared to the
transparent laminate films according to the comparative examples 1
and 2, the transmission attenuation is still large, and the radio
wave transparency is still poor.
[0268] In contrast, for the transparent laminate films according to
the embodiments 3 and 4, as FIG. 5 and FIG. 6 illustrate, cracks
having a width of about 10 .mu.m are formed in the laminate
structures by the laser processing. Due to the grooves introduced
into the laminate structures, the overall surface resistances of
the films are 150.OMEGA./.quadrature. or more. That is, the metal
layers in the laminate structures are broken due to the grooves so
that the overall surface resistances of the films become
150.OMEGA./.quadrature. or more. Therefore, the films have good
radio wave transparency. In addition, because the grooves are
formed in a lattice-like shape, as compared to the case where the
grooves are formed in a slit-like shape, directionality in the
surface resistance is unlikely to appear so that the films also
have superior uniformity in the surface resistance.
[0269] Further, because the width of the grooves is 30 .mu.m or
less, the grooves are hardly visible to human eyes when used and
thus the films have a good appearance. In the above laminate
structures, the metal oxide layers such as the TiO.sub.2 layers and
the metal layers such as the Ag--Cu alloy layers and the like are
laminated. Therefore, good visible light transparency and solar
radiation shielding capability can be achieved. Reduction in
visible light transparency and solar radiation shielding capability
due to the introduction of the grooves formed by the laser
processing is hardly seen.
[0270] According to Table 7, the following is clear. That is, for
the transparent laminate films according to the comparative
examples 1 and 2, grooves due to cracks are not formed in the
laminate structures. Therefore, the metal layers in the laminate
structures are continuous, conductivity is high, and it is
difficult to achieve an overall surface resistance of
150.OMEGA./.quadrature. or more for the films. For this reason, the
transmission attenuation becomes large, and radio wave transparency
is poor.
[0271] In contrast, for the transparent laminate films according to
the embodiments 5-8, as FIG. 7 and FIG. 8 illustrate, there are
numerous cracks having a width of about 2-3 .mu.m formed in the
laminate structures. Due to the cracks introduced into the laminate
structures, the overall surface resistances of the films are
150.OMEGA./.quadrature. or more. That is, the metal layers in the
laminate structures are broken due to the cracks so that the
overall surface resistances of the films become
150.OMEGA./.quadrature. or more. Therefore, the films have good
radio wave transparency. In addition, because there are numerous
cracks, directionality in the surface resistance is unlikely to
appear so that the films also have superior uniformity in the
surface resistance.
[0272] Further, because the width of the grooves is 30 .mu.m or
less, the grooves are hardly visible to human eyes when used and
thus the films have a good appearance. In the above laminate
structures, the metal oxide layers such as the TiO.sub.2 layers and
the metal layers such as the Ag--Cu alloy layers and the like are
laminated. Therefore, good visible light transparency and solar
radiation shielding capability can be achieved. Reduction in
visible light transparency and solar radiation shielding capability
due to the introduction of the cracks is hardly seen.
[0273] When making a comparison between the embodiments, the
numerous cracks formed by uniaxial stretching are in a direction
perpendicular to the tensile direction (FIG. 7). In contrast, the
numerous cracks formed by biaxial stretching are irregular and
directionless (FIG. 8). It is clear that, when the stretching is
biaxial stretching, directionality in the surface resistance is
unlikely to appear, and a transparent laminate film having superior
uniformity in the surface resistance is likely to be obtained.
[0274] According to Table 8, the following is clear. That is, for
the transparent laminate films according to the comparative
examples 7 and 8, the laminate structure is formed on the surface
(PET surface) on the side opposite to the easy adhesion layer side
of the PET film. Therefore, cracks are not formed during the
formation of the laminate structure, continuity of the metal layers
is maintained, and the surface resistance is small. Thus, the
transmission attenuation is large, and the radio wave transparency
is poor.
[0275] In contrast, for the transparent laminate films according to
the embodiments 9 and 10, as FIG. 9 illustrates, despite the
omission of the groove formation process, there are numerous cracks
having a width of about 2-3 .mu.m formed in the laminate
structures. Due to the cracks introduced into the laminate
structures, the overall surface resistances of the films are
150.OMEGA./.quadrature. or more. That is, the metal layers in the
laminate structures are broken by the cracks formed during the
formation of the laminate structures so that the overall surface
resistances of the films become 150.OMEGA./.quadrature. or more.
Therefore, the films have good radio wave transparency. In
addition, because there are numerous cracks, directionality in the
surface resistance is unlikely to appear so that the films also
have superior uniformity in the surface resistance.
[0276] Further, because the width of the grooves is 30 .mu.m or
less, the grooves are hardly visible to human eyes when used and
thus the films have a good appearance. In the above laminate
structures, the metal oxide layers such as the TiO.sub.2 layers and
the metal layers such as the Ag--Cu alloy layers and the like are
laminated. Therefore, good visible light transparency and solar
radiation shielding capability can be achieved. Reduction in
visible light transparency and solar radiation shielding capability
due to the introduction of the cracks is hardly seen.
[0277] From the above results, it is confirmed that the transparent
laminate film according to the present invention has a combination
of visible light transparency, soar radiation shielding capability,
radio wave transparency, and a good appearance.
[0278] In the above, the embodiments and examples of the present
invention were explained. However, the present invention is not
intended to be limited to the embodiments and examples. Various
modifications are possible within the scope without departing from
the spirit of the present invention.
* * * * *