U.S. patent application number 13/044704 was filed with the patent office on 2011-07-07 for powder mixture to be made into evaporation source material for use in ion plating, evaporation source material for use in ion plating and method of producing the same, and gas barrier sheet and method of producing the same.
This patent application is currently assigned to Dai Nippon Printing Co., Ltd.. Invention is credited to Yoshihiro KISHIMOTO.
Application Number | 20110163276 13/044704 |
Document ID | / |
Family ID | 40158904 |
Filed Date | 2011-07-07 |
United States Patent
Application |
20110163276 |
Kind Code |
A1 |
KISHIMOTO; Yoshihiro |
July 7, 2011 |
POWDER MIXTURE TO BE MADE INTO EVAPORATION SOURCE MATERIAL FOR USE
IN ION PLATING, EVAPORATION SOURCE MATERIAL FOR USE IN ION PLATING
AND METHOD OF PRODUCING THE SAME, AND GAS BARRIER SHEET AND METHOD
OF PRODUCING THE SAME
Abstract
A powder mixture to be made into an evaporation source material
for use in ion plating, and an evaporation source material useful
for ion plating and a method of producing it, and a gas barrier
sheet and a method of producing it. The powder mixture comprises
100 parts by weight of silicon oxide powder and 5 to 100 parts by
weight of a conductive material powder. Preferably, both the
silicon oxide powder and the conductive material powder have a mean
particle diameter of 5 .mu.m or less. The conductive material
powder is preferably a powder of at least one material selected
from metals and electrically conductive metallic oxides, nitrides
and acid nitrides. The evaporation source material for use in ion
plating is in the form of agglomerates having a mean particle
diameter of 2 mm or more, or a block, obtained by granulating or
compression-molding the powder mixture.
Inventors: |
KISHIMOTO; Yoshihiro;
(Kashiwa-Shi, JP) |
Assignee: |
Dai Nippon Printing Co.,
Ltd.
Shinjuku-Ku
JP
|
Family ID: |
40158904 |
Appl. No.: |
13/044704 |
Filed: |
March 10, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12141309 |
Jun 18, 2008 |
7947377 |
|
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13044704 |
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Current U.S.
Class: |
252/512 ;
252/500; 252/519.54; 252/520.1; 252/521.3; 427/527 |
Current CPC
Class: |
C23C 14/10 20130101;
C23C 14/28 20130101; Y10T 428/31667 20150401; C09D 1/00 20130101;
C23C 14/562 20130101 |
Class at
Publication: |
252/512 ;
252/500; 252/519.54; 252/520.1; 252/521.3; 427/527 |
International
Class: |
C23C 14/14 20060101
C23C014/14; H01B 1/04 20060101 H01B001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 20, 2007 |
JP |
2007-162497 |
Claims
1. A powder mixture to be made into an evaporation source material
for use in ion plating, comprising 100 parts by weight of silicon
oxide powder, and 5 parts by weight or more and 100 parts by weight
or less of a conductive material powder.
2. The powder mixture according to claim 1, wherein the silicon
oxide powder has a mean particle diameter of 5 .mu.m or less, and
the conductive material powder has a mean particle diameter of 5
.mu.m or less.
3. The powder mixture according to claim 1, wherein the silicon
oxide powder has a specific surface area of 600 m.sup.2/g or
larger.
4. The powder mixture according to claim 1, wherein the conductive
material powder comprises at least one material selected from
metals and electrically conductive metallic oxides, nitrides and
acid nitrides.
5. The powder mixture according to claim 4, wherein the conductive
material powder comprises zinc oxide.
6. The powder mixture according to claim 4, wherein the conductive
material powder comprises tin oxide.
7. A method of producing an evaporation source material for use in
ion plating, comprising the steps of: preparing a powder mixture
comprising 100 parts by weight of silicon oxide powder and 5 parts
by weight or more and 100 parts by weight or less of a conductive
material powder, and granulating or compression-molding the powder
mixture into an evaporation source material for use in ion plating,
in a predetermined form.
8. The method according to claim 7, wherein the silicon oxide
powder has a mean particle diameter of 5 .mu.m or less, and the
conductive material powder has a mean particle diameter of 5 .mu.m
or less.
9. The method according to claim 7, wherein the step of making the
powder mixture into an evaporation source material in a
predetermined form comprises the step of granulating or
compression-molding the silicon oxide powder and the conductive
material powder, the components of the powder mixture, into
agglomerates having a mean particle diameter of 2 mm or more, or a
block.
10. The method according to claim 9, wherein the step of making the
powder mixture into an evaporation source material in a
predetermined form further comprises the step of heating the
agglomerates or block obtained by granulation or compression
molding.
11. The method according to claim 10, wherein the step of making
the powder mixture into an evaporation source material in a
predetermined form further comprises the step of sintering the
agglomerates or block obtained by granulation or compression
molding.
12. An evaporation source material for use in ion plating, that is
in the form of agglomerates having a mean particle diameter of 2 mm
or more, or a block, obtained by granulating or compression-molding
a powder mixture comprising 100 parts by weight of silicon oxide
powder and 5 parts by weight or more and 100 parts by weight or
less of a conductive material powder.
13. The evaporation source material according to claim 12, wherein
the silicon oxide powder has a mean particle diameter of 5 .mu.m or
less, and the conductive material powder has a mean particle
diameter of 5 .mu.m or less.
14. The evaporation source material according to claim 12, wherein
the conductive material powder comprises at least one material
selected from metals and electrically conductive metallic oxides,
nitrides and acid nitrides.
15. The evaporation source material according to claim 14, wherein
the conductive material powder comprises zinc oxide.
16. The evaporation source material according to claim 14, wherein
the conductive material powder comprises tin oxide.
17. A method of producing a gas barrier sheet, comprising the steps
of: preparing an evaporation source material for use in ion
plating, in a predetermined form, by compression-molding or
granulating a powder mixture comprising 100 parts by weight of
silicon oxide powder and 5 parts by weight or more and 100 parts by
weight or less of a conductive material powder, and depositing a
gas barrier film on a substrate by ion plating using as a source
the evaporation source material.
18. The method according to claim 17, wherein the silicon oxide
powder has a mean particle diameter of 5 .mu.m or less, and the
conductive material powder has a mean particle diameter of 5 .mu.m
or less.
19. The method according to claim 17, wherein the conductive
material powder comprises at least one material selected from
metals and electrically conductive metallic oxides, nitrides and
acid nitrides.
20. A gas barrier sheet comprising a substrate and a gas barrier
film formed at least on one side of the substrate, the gas barrier
film being Si--O--Sn film in which the number of Si atoms, that of
O atoms and that of Sn atoms is in the ratio of
100:(150-400):(2-60), the ratio being constant along the thickness
of the film.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S.
application Ser. No. 12/141,309, filed Jun. 18, 2008, and claims
the benefit of Japanese Patent Application No. 2007-162497, filed
on Jun. 20, 2007, which is herein incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a powder mixture to be made
into an evaporation source material for use in ion plating, an
evaporation source material for use in ion plating and a method of
producing the same, and a gas barrier sheet and a method of
producing the same. More particularly, the present invention
relates to a powder mixture to be made into an evaporation source
material for use in ion plating, capable of forming a gas barrier
film that is dense and has good adhesive properties, and to
others.
BACKGROUND OF THE INVENTION
[0003] A gas barrier sheet having, on a substrate, a film of an
inorganic oxide such as silicon oxide or aluminum oxide, serving as
a gas barrier film, has been proposed as a gas barrier sheet
impermeable to oxygen gas, water vapor, etc. Since gas barrier
sheets of this sort are excellent in transparency and have little
influence on environments, demand for them is highly expected to
grow in such areas as packaging materials.
[0004] Besides vacuum vapor deposition and sputtering, ion plating
is employed as a process of depositing an inorganic oxide film that
serves as a gas barrier film. In terms of adhesion to substrate and
denseness, a gas barrier film formed by ion plating is superior to
one deposited by vacuum vapor deposition and is comparable to one
formed by sputtering. On the other hand, the rate of gas barrier
film deposition in ion plating is higher than that in sputtering
and is nearly equal to that in vacuum vapor deposition.
[0005] A gas barrier film formed by ion plating having the
above-described features is described in Japanese Laid-Open Patent
Publication No. 2000-272044 (Patent Document 1), for example.
Patent Document 1 (claim 1) describes a transparent barrier film
that is a thin film formed by ion plating using as a source
SiO.sub.x (0.ltoreq.x.ltoreq.2), composed mainly of silicon oxide
(SiO.sub.y (1.5.ltoreq.y.ltoreq.2)), having an oxygen permeability
of 0.02-0.5 cc/m.sup.2day.
[0006] Silicon oxide materials are inexpensive. They are therefore
suitable for use as gas barrier films in such areas as packaging
materials for foods and the like in which there is a demand for
reduction in cost.
[0007] The gas barrier film described in Patent Document 1 has the
required gas barrier properties. In recent years, however, demands
for packaging materials of better performance have become stronger
than ever, and the present goal in this area is making an overall
improvement in gas barrier properties by suppressing not only
oxygen permeability but also water vapor permeability. For example,
also in such areas as foods in which packaging materials require a
large reduction in cost, there is a growing demand for development
of gas barrier sheets having more excellent gas barrier properties
than ever, without an increase in cost.
[0008] The present invention was accomplished in order to fulfill
the above-described goal in the art. An object of the present
invention is therefore to provide a powder mixture to be made into
an evaporation source material for use in ion plating, capable of
forming a gas barrier film that is dense and is excellent in gas
barrier properties, while keeping the cost low. More specifically,
an object of the present invention is to provide a powder mixture
to be made into an evaporation source material useful for ion
plating, an evaporation source material for use in ion plating and
a method of producing it, and a gas barrier sheet and a method of
producing it.
SUMMARY OF THE INVENTION
[0009] In the course of studies we made in order to produce gas
barrier sheets having enhanced gas barrier properties without
increasing costs, we found that it is possible to obtain
significantly enhanced gas barrier properties by improving
evaporation source materials to be used in ion plating.
[0010] A powder mixture to be made into an evaporation source
material for use in ion plating, that fulfils the above object of
the invention, is characterized by comprising 100 parts by weight
of silicon oxide powder having a mean particle diameter of 5 .mu.m
or less and 5 parts by weight or more and 100 parts by weight or
less of a conductive material powder having a mean particle
diameter of 5 .mu.m or less.
[0011] According to the present invention, the powder mixture to be
made into an evaporation source material for use in ion plating
comprises 100 parts by weight of silicon oxide powder and 5 parts
by weight or more and 100 parts by weight or less of a conductive
material powder, so that when an evaporation source material
obtained by compression-molding or granulating the powder mixture
is used in ion plating as a source, plasma injected for film
deposition concentrates at the evaporation source material and
easily penetrates into it via the conductive material, causing
efficiently the excitation of the evaporation source material.
Consequently, there is deposited a gas barrier film having
significantly enhanced gas barrier properties. It is preferred that
the mean particle diameter of the silicon oxide powder be 100 .mu.m
or less, and that the mean particle diameter of the conductive
material powder be 100 .mu.m or less. It is more preferred that the
mean particle diameter of the silicon oxide powder be 5 .mu.m or
less, and that the mean particle diameter of the conductive
material powder be 5 .mu.m or less.
[0012] In the powder mixture of the invention, to be made into an
evaporation source material for use in ion plating, when the powder
mixture is made into an evaporation source material for use in ion
plating by granulation, it is preferred that the silicon oxide
powder have a specific surface area of 600 m.sup.2/g or larger.
[0013] According to this invention, since the silicon oxide powder
has a specific surface area of 600 m.sup.2/g or more, it can easily
adsorb the conductive material powder that is mixed with it, and
Si-conductive material network is satisfactorily incorporated in
Si--O network. On the other hand, when the powder mixture is made
into an evaporation source material for use in ion plating by
compression molding, it is preferred that the silicon oxide powder
have a specific surface area of 1 to 60 m.sup.2/g.
[0014] In the powder mixture of the invention, to be made into an
evaporation source material for use in ion plating, it is preferred
that the conductive material powder comprise at least one material
selected from metals and electrically conductive metallic oxides,
nitrides and acid nitrides. It is more preferred that the
conductive material powder comprise zinc oxide or tin oxide.
[0015] According to this invention, the conductive material powder
comprises at least one material selected from metals and
electrically conductive metallic oxides, nitrides and acid
nitrides, so that, when an evaporation source material is produced
by heating or sintering the powder mixture, the conductive material
is hardly oxidized in the heating or sintering step and tends to
remain in the silicon oxide while maintaining its conductivity,
which makes it easy to control the composition of the evaporation
source material.
[0016] A method of the present invention, for producing an
evaporation source material for use in ion plating, that fulfils
the above object of the invention, is characterized by comprising
the steps of preparing a powder mixture comprising 100 parts by
weight of silicon oxide powder having a mean particle diameter of 5
.mu.m or less and 5 parts by weight or more and 100 parts by weight
or less of a conductive material powder having a mean particle
diameter of 5 .mu.m or less, and granulating or compression-molding
the powder mixture into an evaporation source material for use in
ion plating, in a predetermined form.
[0017] According to this invention, the production method comprises
the steps of preparing the above-described powder mixture to be
made into an evaporation source material for use in ion plating,
and granulating or compression-molding the powder mixture into an
evaporation source material in a predetermined form, so that when
the evaporation source material obtained by granulation or
compression molding is used as a source in ion plating, plasma
injected for film deposition concentrates at the evaporation source
material and easily penetrates into it via the conductive material,
causing efficiently the excitation of the evaporation source
material. Consequently, there is deposited a gas barrier film
having significantly enhanced gas barrier properties. It is
preferred that the mean particle diameter of the silicon oxide
powder be 100 .mu.m or less, and that the mean particle diameter of
the conductive material powder be 100 .mu.m or less. It is more
preferred that the mean particle diameter of the silicon oxide
powder be 5 .mu.m or less, and that the mean particle diameter of
the conductive material powder be 5 .mu.m or less.
[0018] In the method of the present invention, for producing an
evaporation source material for use in ion plating, it is preferred
that the step of making the powder mixture into an evaporation
source material in a predetermined form comprise the step of
granulating or compression-molding the silicon oxide powder and the
conductive material powder, the components of the powder mixture,
into agglomerates having a mean particle diameter of 2 mm or more,
or a block. Further, in the production method, it is preferred that
the step of making the powder mixture into an evaporation source
material in a predetermined form further comprise the step of
heating the agglomerates or block obtained by granulation or
compression molding. Alternatively, it is preferred that the step
of making the powder mixture into an evaporation source material in
a predetermined form further comprise the step of sintering the
agglomerates or block obtained by granulation or compression
molding.
[0019] According to this invention, in the step of making the
powder mixture into an evaporation source material in a
predetermined form, since the silicon oxide powder and the
conductive material powder, the components of the powder mixture,
are granulated or compression-molded into agglomerates having a
mean particle diameter of 2 mm or more, or a block, the evaporation
source material obtained is hardly scattered when vaporized.
[0020] An evaporation source material of the invention, for use in
ion plating, that fulfils the object of the invention, is in the
form of agglomerates having a mean particle diameter of 2 mm or
more, or a block, obtained by granulating or compression-molding a
powder mixture comprising 100 parts by weight of silicon oxide
powder having a mean particle diameter of 5 .mu.m or less and 5
parts by weight or more and 100 parts by weight or less of a
conductive material powder having a mean particle diameter of 5
.mu.m or less.
[0021] According to this invention, the evaporation source material
is in the form of agglomerates having a mean particle diameter of 2
mm or more, or a block, obtained by granulating or
compression-molding a powder mixture comprising 100 parts by weight
of silicon oxide powder and 5 parts by weight or more and 100 parts
by weight or less of a conductive material powder, so that, when it
is used as a source in ion plating, plasma injected for film
deposition concentrates at the evaporation source material and
easily penetrates into it via the conductive material, causing
efficiently the excitation of the evaporation source material.
Consequently, there is deposited a gas barrier film having
significantly enhanced gas barrier properties. Although some
manufacturers of materials for use in vacuum deposition have
developed evaporation source materials for use in ion plating, most
of these materials are merely modifications of materials for use as
sources in vacuum vapor deposition or as targets in sputtering. It
is the present situation that there have not yet been proposed
evaporation source materials for use in ion plating, capable of
forming films improved in film quality. It is preferred that the
mean particle diameter of the silicon oxide powder be 100 .mu.m or
less, and that the mean particle diameter of the conductive
material powder be 100 .mu.m or less. It is more preferred that the
mean particle diameter of the silicon oxide powder be 5 .mu.m or
less, and that the mean particle diameter of the conductive
material powder be 5 .mu.m or less.
[0022] In the evaporation source material of the invention, for use
in ion plating, it is preferred that the conductive material powder
comprise at least one material selected from metals and
electrically conductive metallic oxides, nitrides and acid
nitrides. It is more preferred that the conductive material powder
comprise zinc oxide or tin oxide.
[0023] According to this invention, the conductive material powder
comprises at least one material selected from metals and
electrically conductive metallic oxides, nitrides and acid
nitrides, so that, when the evaporation source material is produced
from the powder mixture by heating or sintering, the conductive
material is hardly oxidized in the heating or sintering step and
tends to remain in the silicon oxide while maintaining its
conductivity, which makes it easy to control the composition of the
evaporation source material.
[0024] A method of the present invention, for producing a gas
barrier sheet, that fulfils the above object of the invention, is
characterized by comprising the steps of preparing an evaporation
source material for use in ion plating, in a predetermined form, by
compression-molding or granulating a powder mixture comprising 100
parts by weight of silicon oxide powder having a mean particle
diameter of 5 .mu.m or less and 5 parts by weight or more and 100
parts by weight or less of a conductive material powder having a
mean particle diameter of 5 .mu.m or less, and depositing a gas
barrier film on a substrate by ion plating using as a source the
evaporation source material.
[0025] According to this invention, the production method comprises
the steps of preparing the above-described evaporation source
material for use in ion plating and depositing a gas barrier film
on a substrate by ion plating using as a source the evaporation
source material. In particular, the evaporation source material of
the invention is used in the production method, so that plasma
injected for film deposition concentrates at the evaporation source
material and easily penetrates into it via the conductive material,
causing efficiently the excitation of the evaporation source
material. Consequently, there is deposited a gas barrier film
having significantly enhanced gas barrier properties. It is
preferred that the mean particle diameter of the silicon oxide
powder be 100 .mu.m or less, and that the mean particle diameter of
the conductive material powder be 100 .mu.m or less. It is more
preferred that the mean particle diameter of the silicon oxide
powder be 5 .mu.m or less, and that the mean particle diameter of
the conductive material powder be 5 .mu.m or less.
[0026] In the method of the present invention, for producing a gas
barrier sheet, it is preferred that the conductive material powder
comprise at least one material selected from metals and
electrically conductive metallic oxides, nitrides and acid
nitrides.
[0027] According to this invention, the conductive material powder
comprises at least one material selected from metals and
electrically conductive metallic oxides, nitrides and acid
nitrides, so that, when the evaporation source material is produced
from the powder mixture by heating or sintering, the conductive
material is hardly oxidized in the heating or sintering step and
tends to remain in the silicon oxide while maintaining its
conductivity, which makes it easy to control the composition of the
evaporation source material.
[0028] A gas barrier sheet of the present invention, that fulfils
the above-described object of the invention, comprises a substrate
and a gas barrier film formed at least on one side of the
substrate, and the gas barrier film is Si--O--Zn film in which the
number of Si atoms, that of O atoms and that of Zn atoms are in the
ratio of 100:(200-500):(2-100), the ratio being constant along the
thickness of the film.
[0029] According to this invention, the gas barrier film is
Si--O--Zn film in which the number of Si atoms, that of O atoms and
that of Zn atoms are in the ratio of 100:(200-500):(2-100), and
this number-of-atoms ratio is constant (scattering: within .+-.10%)
along the thickness of the film, so that the gas barrier sheet has
the gas barrier film having film quality uniform along the
thickness of the film. The gas barrier sheet is therefore
significantly excellent in gas barrier properties. The
number-of-atoms ratio is herein on a bulk basis.
[0030] A gas barrier sheet of the present invention, that fulfils
the above-described object, comprises a substrate and a gas barrier
film formed at least on one side of the substrate, and the gas
barrier film is Si--O--Sn film in which the number of Si atoms,
that of O atoms and that of Sn atoms are in the ratio of
100:(150-400):(2-60), the ratio being constant along the thickness
of the film.
[0031] According to this invention, the gas barrier film is
Si--O--Sn film in which the number of Si atoms, that of O atoms and
that of Sn atoms are in the ratio of 100:(150-400):(2-60), and this
number-of-atoms ratio is constant along the thickness of the film,
so that the gas barrier sheet has the gas barrier film having film
quality uniform along the thickness of the film. The gas barrier
sheet is therefore significantly excellent in gas barrier
properties. The number-of-atoms ratio is herein on a bulk
basis.
[0032] According to the powder mixture of the invention, to be made
into an evaporation source material for use in ion plating, when an
evaporation source material obtained by compression-molding or
granulating the powder mixture is used as a source in ion plating,
plasma injected for film deposition concentrates at the evaporation
source material and easily penetrates into it via the conductive
material, causing efficiently the excitation of the evaporation
source material. Consequently, there is deposited a gas barrier
film having significantly enhanced gas barrier properties.
[0033] According to the method of the invention, for producing an
evaporation source material for use in ion plating, when an
evaporation source material obtained by compression-molding or
granulating the powder mixture is used as a source in ion plating,
plasma injected for film deposition concentrates at the evaporation
source material and easily penetrates into it via the conductive
material, causing efficiently the excitation of the evaporation
source material. Consequently, there is deposited a gas barrier
film having significantly enhanced gas barrier properties.
[0034] According to the evaporation source material of the
invention, for use in ion plating, plasma injected for film
deposition concentrates at the evaporation source material and
easily penetrates into it via the conductive material, causing
efficiently the excitation of the evaporation source material.
Consequently, there is deposited a gas barrier film having
significantly enhanced gas barrier properties. Although some
manufacturers of materials for use in vacuum deposition have
developed evaporation source materials for use in ion plating, most
of these materials are merely modifications of materials for use as
sources in vacuum vapor deposition or as targets in sputtering. It
is the present situation that there have not yet been proposed
evaporation source materials for use in ion plating, capable of
forming films improved in film quality.
[0035] According to the method of the present invention, for
producing a gas barrier sheet, since the evaporation source
material of the invention is used in ion plating, plasma injected
for film deposition concentrates at the evaporation source material
and easily penetrates into it via the conductive material, causing
efficiently the excitation of the evaporation source material.
Consequently, there is deposited a gas barrier film significantly
enhanced in gas barrier properties.
[0036] According to the gas barrier sheet of the present invention,
since it has a gas barrier film having film quality uniform along
the thickness of the film, as well as high density, denseness and
excellent adhesive properties, it can exhibit extremely excellent
gas barrier properties.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a diagrammatical cross-sectional view of a gas
barrier sheet of the present invention.
[0038] FIG. 2 is a view showing the structure of an ion-plating
device of hollow cathode type that was used in Examples.
DETAILED DESCRIPTION OF THE INVENTION
[0039] Embodiments of the present invention will be described
hereinafter in detail. However, the present invention is not
limited to the following embodiments and is susceptible to
modifications without departing from the spirit of this disclosure
and the scope of the appended claims.
[0040] (Powder Mixture to be made into Evaporation Source Material
for Use in Ion Plating)
[0041] A powder mixture of the invention, to be made into an
evaporation source material for use in ion plating (sometimes
referred to simply as a "powder mixture" in this specification) is
a powder mixture to be made into an evaporation source that is used
in ion plating as a source of atoms to be ionized. Specifically,
the powder mixture comprises 100 parts by weight of silicon oxide
powder having a mean particle diameter of 100 .mu.m or less,
preferably 5 .mu.m or less, and 5 parts by weight or more and 100
parts by weight or less of a conductive material powder having a
mean particle diameter of 100 .mu.m or less, preferably 5 .mu.m or
less.
[0042] When an evaporation source material made from the above
powder mixture is used as a source in ion plating, plasma injected
for film deposition concentrates at the evaporation source material
and easily penetrates into it via the conductive material, causing
efficiently the excitation of the evaporation source material.
Consequently, there is deposited a gas barrier film having
significantly enhanced gas barrier properties. The following is the
possible reason why the evaporation source material obtained from
the powder mixture by compression molding or granulation has the
above-described effects on gas barrier film deposition.
[0043] In the present invention, since a conductive material is
used together with silicon oxide, an insulating material, to
produce an evaporation source material, plasma injected from a
plasma gun easily concentrates at the evaporation source material.
If a single insulating material, such as silicon oxide, is exposed
to plasma, the charge on its surface increases, and the plasma
discharges to the non-floating parts (earth-potential parts) of a
deposition chamber and becomes unstable. Consequently, it becomes
difficult to conduct film deposition continuously. In the present
invention, on the other hand, a conductive material is present in
the evaporation source material, so that plasma easily concentrates
at the evaporation source material, which makes it easy to conduct
film deposition continuously.
[0044] Furthermore, in the present invention, since silicon oxide
powder having a mean particle diameter of 100 .mu.m or less,
preferably 5 .mu.m or less, is mixed with a specified amount of a
conductive material powder having a mean particle diameter of 100
.mu.m or less, preferably 5 .mu.m or less, there can be obtained a
powder mixture excellent in uniformity of dispersion. It is
therefore assumed that, also in the evaporation source material for
use in ion plating, obtained from the powder mixture, the
conductive material is dispersed uniformly in the silicon oxide.
The conductive material uniformly dispersed in the evaporation
source material makes plasma easily penetrate into the evaporation
source material.
[0045] It is assumed that the concentration of plasma at the
evaporation source material and the penetration of plasma into the
evaporation source material synergically act to excite efficiently
the evaporation source material. It is also assumed that, since the
evaporation source material is efficiently excited, the rate of
ionization increases, which makes it possible to obtain a gas
barrier film having greatly improved film quality.
[0046] An evaporation source material that sublimes, i.e.,
undergoes a direct change in state from solid to gas, when exposed
to plasma is usually used in ion plating. This is because a
material that undergoes a change in state from solid to gas via
liquid when exposed to plasma is at a disadvantage in that it makes
the rate of film deposition lower to increase deposition time,
since it becomes liquid before becoming gaseous. In the course of
our studies, we found the following. Of silicon oxide materials,
especially silicon dioxide has the property of undergoing a change
in state from solid to gas via liquid when exposed to plasma, and
an evaporation source material composed of a combination of silicon
dioxide and a conductive material is more readily melted and shows
the increased tendency to be vaporized after becoming liquid.
Therefore, the use of a conductive material together with silicon
oxide seems to be inadequate from the viewpoint of increase in the
rate of film deposition and decrease in deposition time in ion
plating. However, we found the following in the course of our
studies. When a conductive material is incorporated in an
evaporation source material, plasma injected from a plasma gun
comes to concentrate at the evaporation source material and the
output of the plasma is thus stabilized, which makes continuous
film deposition easier. In addition to this, we also found the
following. Since the small-particle-sized conductive material
incorporated in the evaporation source material accelerates melting
of the evaporation source material, the plasma injected penetrates
more fully into the evaporation source material, and the
evaporation source material is thus excited efficiently.
Consequently, the deposited gas barrier film has significantly
enhanced gas barrier properties. Such a significant enhancement of
gas barrier properties is very advantageous to a gas barrier
sheet.
[0047] Any powder can be used as the silicon oxide powder as long
as it is a powder of a compound consisting of silicon and oxygen,
and silicon dioxide powder is preferably used in the present
invention. Silicon dioxide powder can be represented by the
chemical formula SiO.sub.x (x=1.8 to 2.2), typically by SiO.sub.2.
The silicon oxide powder is in powder form, and more specifically,
it is a powder having a mean particle diameter of 100 .mu.m or
less, preferably 5 .mu.m or less. The "mean particle diameter"
herein is a value obtained from measurements on apparatus for
particle size distribution measurement (the Coulter Counter
method), using as a sample a specified amount, e.g., 1 g, of a
powder. Although the silicon oxide powder may contain small amounts
of impurities and other elements, its purity is usually as high as
99.9% or more in the present invention.
[0048] Any powder can be used as the conductive material powder as
long as it is a powder of a material having electrical
conductivity, and a powder of an inorganic material is preferably
used in the invention. Examples of conductive materials useful
herein include materials whose volume resistivity values are 1.4
.mu..OMEGA.cm or more and 1 k.OMEGA.cm or less. In the present
invention, the volume resistivity is determined by the testing
method using a four-point prove array, specified in JIS-K7194.
Examples of conductive materials having volume resistivity values
in the above range include metals, alloys, and electrically
conductive compounds.
[0049] First, the case where a metal or alloy is used as the
conductive material will be described. In this case, it is
preferable to pay attention to the following points according to
the type of the metal or alloy to be used and to the method to be
employed to produce the evaporation source material. As will be
described later, an evaporation source material of the present
invention can be obtained by granulating or compression-molding the
powder mixture into a predetermined form and heating or sintering
the granulated or compression-molded one. When the evaporation
source material is obtained by heating or sintering from the powder
mixture containing as the conductive material powder a metal or
alloy, it is desirable to control the degree of oxidization of the
metal or alloy according to its type. More specifically, a metal or
alloy tends to react with oxygen either in the air or in the
silicon oxide to cause oxidation in the heating or sintering step.
For this reason, it is preferred that the metal or alloy to be used
in the powder mixture be a material that retains conductivity when
slightly oxidized, or a material that retains conductivity even
when considerably oxidized.
[0050] The material that retains conductivity when slightly
oxidized is at least one material selected from such metals as
aluminum, silicon, copper, silver, nickel, chromium, gold, white
gold, indium, tin, zinc, gallium and germanium, and alloys of these
metals. For example, of the above metals and alloys, aluminum comes
to have insulating properties when oxidized to Al.sub.2O.sub.3.
However, by feeding to aluminum only a small amount of oxygen, it
is possible to maintain the conductivity of aluminum. Therefore, in
the case where a metal or alloy that retains conductivity when
oxidized slightly is used, it is possible to ensure the electrical
conductivity of the conductive material contained in the
evaporation source material by controlling various conditions such
as the heating or sintering temperature and the atmosphere in which
the heating or sintering step is performed. Of the above metals and
alloys, gold, silver, copper, white gold, indium, tin and zinc, and
alloys of these metals are preferred from the viewpoint of
electrical conductivity, and aluminum, tin and zinc are preferred
from the viewpoint of cost.
[0051] Examples of the material that retains conductivity even when
considerably oxidized include such metals as indium, zinc, tin and
cerium, and alloys of these metals. Of these metals and alloys,
zinc itself is conductive, and zinc oxide (ZnO) is also conductive.
It is therefore possible to ensure the electrical conductivity of
the conductive material contained in the evaporation source
material obtained by heating or sintering, without controlling the
degree of oxidization of the conductive material. For this reason,
when such a metal or alloy is used, there is no need to control the
degree of its oxidization. Of the above-described materials,
indium, zinc and tin, and alloys of these metals are preferred from
the viewpoint of conductivity, and zinc and zinc alloys are
preferred from the viewpoint of cost.
[0052] On the other hand, in the case where an evaporation source
material is obtained by granulating the powder mixture into a
predetermined form, there is sometimes no need to take oxidation of
the metal or alloy into consideration. For example, when the powder
mixture is granulated by such a method as pressing, without
conducting heating or sintering, the above-described influence of
oxidization can be minimized. Even when heating or sintering is
conducted, if it is conducted in an inert gas or in vacuum, the
influence of oxidization can be minimized. For this reason, a metal
or alloy selected from a wide variety of materials can be used
irrespective of whether it retains conductivity when oxidized
slightly or even when oxidized considerably. Specifically, such a
material can be selected from the above-enumerated metals and
alloys.
[0053] Next, the case where an electrically conductive compound is
used as the conductive material will be described. Preferably, the
conductive compound is at least one selected from electrically
conductive metallic oxides, nitrides and acid nitrides. Metallic
oxides or nitrides include double oxides or nitrides that are
oxides or nitrides of two or more metallic elements. The same
applies to metallic acid nitrides. Since such a conductive compound
is mostly in the state of being oxidized and/or nitrided and
chemically stable, it is hardly oxidized in the heating or
sintering step in the production of the evaporation source material
and tends to remain in the silicon oxide while maintaining its
conductivity. This makes it easy to control the composition of the
evaporation source material. From the viewpoint of conductivity and
stability, it is preferable to use, as the conductive compound, an
oxide, nitride or acid nitride of at least one metal selected from
indium, zinc, tin, and cerium, more preferably from indium, zinc,
and tin. More specific examples of such conductive materials are
preferably tin oxide, zinc oxide, and ITO.
[0054] Of the above-described conductive materials, a metal or
alloy that retains conductivity even when oxidized considerably, or
a conductive compound, is preferably used to produce an evaporation
source material by heating or sintering the powder mixture. This is
because it is not necessary to control the oxidation of such a
material and is easy to control the composition of the evaporation
source material to be produced, which is convenient for industrial
production.
[0055] The conductive material powder is in powder form. More
specifically, it is a powder having a mean particle diameter of 100
.mu.m or less, preferably 5 .mu.m or less. The mean particle
diameter of the conductive material powder is determined by the
same method as is used to determine the mean particle diameter of
the silicon oxide powder. Although the conductive material powder
may contain small amounts of impurities and other elements, its
purity is usually as high as 99.9% or more in the present
invention.
[0056] In the powder mixture of the invention, both the mean
particle diameter of the silicon oxide powder and that of the
conductive material powder are 100 .mu.m or less, preferably 5
.mu.m or less, more preferably 3 .mu.m or less. As long as the two
powders have mean particle diameters in the above range, it is easy
to mix them with each other, and there can be obtained a powder
mixture without non-uniformity in dispersion. In a small portion
(unit volume) of an evaporation source material produced by
compression-molding or granulating such a powder mixture, the fine
silicon oxide powder and the fine conductive material powder are
uniformly dispersed, and the individual powder can be well exposed
to plasma that occurs in an ion-plating device. Particularly within
the evaporation source material, the conductive material is present
in the silicon oxide, so that plasma injected from a plasma gun
concentrates at the evaporation source material. In addition to
this, since the conductive material is uniformly mixed with the
silicon oxide, the plasma injected for film deposition easily
penetrates into the evaporation source material via the conductive
material, causing efficiently the excitation of the evaporation
source material. It is therefore easy to obtain a gas barrier film
having significantly enhanced gas barrier properties.
[0057] Although the mean particle diameter of the silicon oxide
powder and that of the conductive material powder have no
particular lower limit, the lower limit is preferably 0.2 .mu.m.
When the two powders have mean particle diameters of 0.2 .mu.m or
more, they are hardly scattered when mixed with each other or when
the powder mixture consisting of the two powders is
compression-molded or granulated, which brings about increase in
productivity.
[0058] On the other hand, when both of, or either one of the mean
particle diameter of the silicon oxide powder and that of the
conductive material powder is in excess of 5 .mu.m, the two powders
are not fully dispersed when mixed with each other. Therefore, even
when the powder mixture obtained is compression-molded or
granulated into an evaporation source material for use in ion
plating, the fine silicon oxide powder and the fine conductive
material powder cannot be uniformly present in a small portion
(unit volume) of the evaporation source material, so that it
becomes difficult to obtain the effects of the evaporation source
material, i.e., the concentration of plasma at the evaporation
source material and the penetration of plasma into the evaporation
source material via the conductive material. Thus, when the two
powders have greater mean particle diameters, the evaporation
source material is excited less sufficiently.
[0059] Preferably, the powder mixture of the invention, to be made
into an evaporation source material for use in ion plating, is
composed mainly of silicon oxide powder. The reason for this is as
follows. Since silicon oxide powder is inexpensive, the use of it
makes possible to produce a powder mixture, an evaporation source
material and a gas barrier sheet at decreased cost. Silicon oxide
powder can therefore be used favorably in such areas as the food
industries in which there is an insistent demand for reduction in
the cost of packaging materials. In the powder mixture of the
invention, to be made into an evaporation source material for use
in ion plating, a specified amount of the conductive material
powder is used together with the silicon oxide powder, in order to
obtain a gas barrier film having enhanced gas barrier properties by
making use of the effects of the conductive material, i.e., the
concentration of plasma at the evaporation source material and the
penetration of plasma into the evaporation source material via the
conductive material. Taking these effects into account, the content
of the conductive material powder in the powder mixture is set to 5
parts by weight or more, preferably 10 parts by weight or more,
more preferably 30 parts by weight or more, and 100 parts by weight
or less, preferably 80 parts by weight or less, and more preferably
70 parts by weight or less, for 100 parts by weight of the silicon
oxide powder. When ion plating is conducted using the evaporation
source material made from the powder mixture containing the
conductive material powder in an amount of the above range, plasma
fully concentrates at the evaporation source material due to the
conductive material present in the evaporation source material, and
readily penetrates into the evaporation source material via the
conductive material, as described above. Consequently, the
evaporation source material is excited efficiently, and there can
thus be easily obtained a gas barrier film having excellent gas
barrier properties.
[0060] When the content of the conductive material powder in the
powder mixture is less than 5 parts by weight for 100 parts by
weight of the silicon oxide powder, the effects of addition of the
conductive material (i.e., the concentration of plasma at the
evaporation source material, and the satisfactory penetration of
plasma into the evaporation source material) may not be easily
obtained. On the other hand, when the content of the conductive
material powder in the powder mixture is more than 100 parts by
weight for 100 parts by weight of the silicon oxide powder, the gas
barrier film obtained is often colored, e.g., brown-colored, and is
hard. Therefore, 100 parts by weight for 100 parts by weight of the
silicon oxide powder is adequate as the upper limit of the
conductive material content, if a gas barrier film is deposited on
a transparent substrate, or if the intended gas barrier sheet is
flexible one.
[0061] If a granulation process is employed in the method of
producing an evaporation source material for use in ion plating,
which will be described later, it is preferred that the silicon
oxide powder have a specific surface area of 600 m.sup.2/g or more.
When the silicon oxide powder has a specific surface area of 600
m.sup.2/g or more, it can easily adsorb the conductive material
powder mixed with it, and Si-conductive material network can be
readily incorporated in Si--O network. For example, silicon oxide
powder having a specific surface area of 600 m.sup.2/g or more has
a greater number of functional groups (silanol groups) in primary
particles and thus has a greater number of adsorption sites, as
compared to the same volume of silicon oxide powder whose specific
surface area is less than 600 m.sup.2/g. Silicon oxide powder
having a specific surface area of less than 600 m.sup.2/g tends to
adsorb only insufficiently the conductive material mixed with it,
and Si-conductive material network is sometimes not fully
incorporated in Si--O network. Further, such silicon oxide powder
is not easily solidified even when granulated, so that it is
sometimes impossible to obtain an evaporation source material in
the form of the desired agglomerates or block. In the present
invention, the specific surface area is measured with an automatic
specific surface area meter (the nitrogen adsorption method, the
BET equation) using as a sample a specified amount (e.g., 1 g) of a
powder.
[0062] Whether Si-conductive material network has been
satisfactorily incorporated in Si--O network or not can be known by
evaluating the film quality of the gas barrier film obtained by ion
plating. That the Si-conductive material network is satisfactorily
incorporated in the Si--O network is confirmed if the conductive
material or the component elements thereof are uniformly
distributed in the gas barrier film, and, moreover, the gas barrier
film is dense. The specific surface area of the silicon oxide
powder is preferably 800 m.sup.2/g or more. Although the specific
surface area has no particular upper limit, silicon oxide powders
having specific surface areas of up to 1000 m.sup.2/g can be used
in the present invention.
[0063] On the other hand, in the case where a compression molding
process such as CI press is used in the method of producing an
evaporation source material for use in ion plating, which will be
described later, it is preferred that the specific surface area of
the silicon oxide powder be from 1 to 60 m.sup.2/g. The use of
silicon oxide powder having a specific surface area of 1-60
m.sup.2/g makes it easier to produce, by compression molding, an
evaporation source material for use in ion plating, in a
predetermined shape.
[0064] As described above, according to the powder mixture of the
invention, to be made into an evaporation source material for use
in ion plating, when an evaporation source material produced by
compression-molding or granulating the powder mixture is used as a
source in ion plating, plasma injected for film deposition
concentrates at the evaporation source material and easily
penetrates into it via the conductive material, causing efficiently
the excitation of the evaporation source material. Consequently,
there is deposited a gas barrier film having significantly enhanced
gas barrier properties.
[0065] (Evaporation Source Material for Use in Ion Plating)
[0066] An evaporation source material of the invention is for use
in ion plating as a source of atoms to be ionized, and it is
obtained by compression-molding or granulating the above powder
mixture of the invention. Specifically, the evaporation source
material is in the form of agglomerates having a mean particle
diameter of 2 mm or more, or a block, obtained by granulating or
compression-molding a powder mixture comprising 100 parts by weight
of silicon oxide powder having a mean particle diameter of 100
.mu.m or less, preferably 5 .mu.m or less, and 5 parts by weight or
more and 100 parts by weight or less of a conductive material
powder having a mean particle diameter of 100 .mu.m or less,
preferably 5 .mu.m or less.
[0067] The evaporation source material in the form of agglomerates
having a mean particle diameter of 2 mm or more, or of a block is
good enough to fulfill the object of the invention, and the mean
particle diameter is preferably 5 mm or more and has no particular
upper limit. Therefore, the evaporation source material may be in
the form of agglomerates having a mean particle diameter of about 2
mm, or even in the form of a block whose size is as large as 10 mm,
50 mm, etc. The reason why the mean particle diameter of
agglomerates constituting the evaporation source material is set to
2 mm or more is as follows. Since particles having a mean particle
diameter of less than 2 mm are very small, an evaporation source
material composed of such fine particles is easily scattered by the
impact of plasma injection in an ion-plating device. Moreover,
placing such an evaporation source material on a boat (hearth) in
an ion-plating device often requires careful handling. The mean
particle diameter has no particular upper limit, but is about 200
mm, if any. Particles with any large mean particle diameter can be
used herein as long as they can be contained in the material
introduction port (hearth) of a deposition chamber. Furthermore,
the particles of the evaporation source material may be in any
shape; they may be circular, elliptic, or rectangular, for example.
A variety of granulation or compression molding processes can be
employed to produce an evaporation source material in the form of
agglomerates or a block. The "mean particle diameter" of the
evaporation source material is a value obtained from measurements
on apparatus for particle diameter distribution measurement (the
Coulter Counter method), using as a sample a specified amount
(e.g., 1 g) of a powder, like the mean particle diameter of the
powder mixture, as described above.
[0068] The elements constituting the silicon oxide powder and the
elements constituting the conductive material powder are in the
form of secondary particles and are distributed uniformly in the
evaporation source material. Due to the actions of the elements
constituting the conductive material powder, plasma injected for
film deposition concentrates at the evaporation source material,
and easily penetrates into it via the conductive material, causing
efficiently the, excitation of the evaporation source material. The
gas barrier film deposited, therefore, has enhanced gas barrier
properties.
[0069] Preferably, the powder mixture of the invention, to be made
into an evaporation source material for use in ion plating, is
composed mainly of silicon oxide powder. The reason for this is as
follows. Since silicon oxide powder is inexpensive, the use of it
makes it possible to produce a powder mixture, an evaporation
source material, and a gas barrier sheet at decreased cost. Silicon
oxide powder can therefore be used favorably in such areas as the
food industries in which there is an insistent demand for reduction
in the cost of packaging materials. In the powder mixture of the
invention, to be made into an evaporation source material for use
in ion plating, a specified amount of a conductive material powder
is used together with the silicon oxide powder, in order to obtain
a gas barrier film with enhanced gas barrier properties by making
use of the effects of the conductive material, that is, the
concentration of plasma at the evaporation source material and the
penetration of plasma into the evaporation source material via the
conductive material. Taking these effects into account, the content
of the conductive material powder in the evaporation source
material is set to 5 parts by weight or more, preferably 10 parts
by weight or more, more preferably 30 parts by weight or more, and
100 parts by weight or less, preferably 80 parts by weight or less,
and more preferably 70 parts by weight or less, for 100 parts by
weight of the silicon oxide powder. When ion plating is conducted
using such an evaporation source material, there can be
satisfactorily obtained the above-described effects of the
conductive material, that is, plasma injected concentrates at the
evaporation source material and easily penetrates into it via the
conductive material. On the other hand, when the content of the
conductive material powder in the evaporation source material is
less than 5 parts by weight for 100 parts by weight of the silicon
oxide powder, it is not easy to obtain the above effects. And when
the content of the conductive material powder in the evaporation
source material is more than 100 parts by weight for 100 parts by
weight of the silicon oxide powder, the gas barrier film obtained
is often colored, e.g., brown-colored, and is hard. Therefore, 100
parts by weight for 100 parts by weight of the silicon oxide powder
is adequate as an upper limit of the conductive material content,
if a gas barrier film is deposited on a transparent member, or if
the intended gas barrier sheet is flexible one.
[0070] Except for the above-described points, the features of the
evaporation source material are the same as those mentioned in the
above description of the powder mixture. For example, the
conductive material in the evaporation source material is
preferably at least one compound selected from electrically
conductive metallic oxides, nitrides and acid nitrides, as
mentioned before. Therefore, those points that have already been
referred in the description of the powder mixture will not be
described any more.
[0071] According to the evaporation source material of the
invention for use in ion plating, plasma injected from a plasma gun
concentrates at the evaporation source material in an ion-plating
device and easily penetrates into it via the conductive material,
causing efficiently the excitation of the evaporation source
material. Consequently, there is deposited a gas barrier film
having significantly enhanced gas barrier properties. Although some
manufacturers of materials for use in vapor deposition have
developed evaporation source materials for use in ion plating, most
of these materials are merely modifications of materials for use as
sources in vacuum vapor deposition or as targets in sputtering. It
is the present situation that there have not yet been proposed
evaporation source materials for use in ion plating, capable of
forming films improved in film quality.
[0072] (Method of Producing Evaporation Source Material for Use in
Ion Plating)
[0073] A method of producing an evaporation source material for use
in ion plating (sometimes referred to simply as a "method of
producing an evaporation source material" in this specification) of
the invention comprises the steps of preparing the above-described
powder mixture of the invention, and compression-molding or
granulating the powder mixture into an evaporation source material
for use in ion plating, in a predetermined form.
[0074] As mentioned in the above description of the powder mixture,
the step of preparing the powder mixture is the step of preparing a
powder mixture to be made into an evaporation source material for
use in ion plating, comprising 100 parts by weight of silicon oxide
powder having a mean particle diameter of 100 .mu.m or less,
preferably 5 .mu.m or less, and 5 parts by weight or more and 100
parts by weight or less of a conductive material powder having a
mean particle diameter of 100 .mu.m or less, preferably 5 .mu.m or
less. In this step, 5 parts by weight or more and 100 parts by
weight or less of a conductive material powder is mixed with 100
parts by weight of silicon oxide powder by means of mixing, such as
a mixer.
[0075] Although the step of making the powder mixture into an
evaporation source material in a predetermined form can be
performed in any manner, it is preferred that this step comprise
the step of granulating or compression-molding the silicon oxide
powder and the conductive material powder, the components of the
powder mixture, into agglomerates having a mean particle diameter
of 2 mm or more, or a block. The evaporation source material
produced in this manner is less scattered when vaporized. Further,
it is preferred that the step of making the powder mixture into an
evaporation source material in a predetermined form further
comprise, after the step of granulating or compression-molding the
silicon oxide powder and the conductive material powder into
agglomerates or a block, the step of heating or sintering the
agglomerates or block.
[0076] A variety of conventional techniques, such as metal mold
press, CI press (cold isostatic press), and RI press (rubber
isostatic press), can be employed to compression-mold the powder
mixture into a predetermined shape. Of these, CI press is most
preferred in the invention. In the heating or sintering step, there
can be employed any conventional means of heating or sintering with
which the compression-molded material can be heated to a
temperature lower than the melting points of its component powders,
thereby combining the powders.
[0077] The heating or sintering step can be performed at any
temperature in the range from preferably 500.degree. C., more
preferably 750.degree. C., to preferably 1500.degree. C., more
preferably 1200.degree. C. By performing the heating or sintering
step at a temperature in the above range, it is possible to degas
the powder mixture satisfactorily and make it into agglomerates
having a mean particle diameter of 2 mm or more, or a block. When
the heating or sintering step is performed at a temperature of less
than 500.degree. C., the powder mixture cannot be heated or
sintered satisfactorily, so that it may not become agglomerates
having a mean particle diameter of 2 mm or more, or a block. On the
other hand, when the heating or sintering step is performed at a
temperature of more than 1500.degree. C., the conductive material
is sometimes oxidized excessively. In the present invention, the
word "sintering" means that a powder mixture is heated so that its
component powders are combined with each other, thereby causing
volume shrinkage in the powder mixture to make it dense. Although
the powder mixture can be heated at a temperature at which
sintering occurs, or higher, it may be heated at a temperature
lower than the sintering temperature, thereby degassing it without
causing sintering.
[0078] Various granulation techniques such as agitation
granulation, fluidized bed granulation and extrusion granulation
can be used as a means of granulation. Specifically, agitation
granulation is a method for producing nearly spherical
agglomerates, in which a powder is placed in a vessel, a liquid
binder is added to the stirred powder to agglomerate it, and the
agglomerates produced are dried. Fluidized bed granulation is a
method for producing relatively bulky agglomerates, in which while
blowing hot air from the bottom of a vessel in which a powder is
placed, a binder is sprayed over the powder slightly floating in
the air, thereby agglomerating the powder, and, at the same time,
drying the agglomerates produced. Extrusion granulation is a method
for producing agglomerates with relatively high density, in which a
wet mass of a powder is cylindrically extruded through a small hole
and is dried. These methods of granulation usually use binders.
When a binder is used, it is usually removed, after granulation, by
heating/sintering the agglomerates at a temperature of 500.degree.
C. or more and 1500.degree. C. or less, for example. Even when no
binder is used, the agglomerates are heated/sintered at a
temperature of 500.degree. C. or more and 1500.degree. C. or less,
for example. With this heating/sintering, degassing can be fully
done and there can be easily obtained agglomerates having a mean
particle diameter of 2 mm or more.
[0079] In the case where a binder is used in compression-molding or
granulating the powder mixture, such a material as starch, wheat
protein, or cellulose can be typically used as the binder, and
other materials can of course be used as well. Usually, the binder
is removed from the compression-molded or granulated one by
heating/sintering.
[0080] According to the method of the invention, for producing an
evaporation source material, the compression-molded or sintered
evaporation source material for use in ion plating, in a
predetermined shape, is advantageous in that plasma injected for
film deposition concentrates at the evaporation source material and
easily penetrates into it via the conductive material, causing
efficiently the excitation of the evaporation source material.
Consequently, there is deposited a gas barrier film having
significantly enhanced gas barrier properties.
[0081] (Gas Barrier Sheet)
[0082] FIG. 1 is a diagrammatic cross-sectional view of a gas
barrier sheet of the present invention. A gas barrier sheet 1 of
the invention comprises a substrate 2 and a gas barrier film 3
formed at least on one side of the substrate 2, as shown in FIG. 1.
The gas barrier film 3 is formed from silicon oxide and a
conductive material that is preferably zinc oxide or tin oxide. As
mentioned in the above description of the powder mixture, zinc and
tin are industrially advantageous because not only they themselves
but also their oxides are electrically conductive. More
specifically, the gas barrier film 3 is Si--O--Zn film in which the
number of Si atoms, that of O atoms and that of Zn atoms are in the
range of 100:(200-500):(2-100), and this number-of-atoms ratio is
constant along the thickness of the film. Alternatively, the gas
barrier film 3 is Si--O--Sn film in which the number of Si atoms,
that of O atoms and that of Sn atoms are in the range of
100:(150-400):(2-60), and this number-of-atoms ratio is constant
along the thickness of the film. Since the gas barrier sheet 1
comprises the gas barrier film 3 having film quality uniform along
the thickness of the film, it is excellent in gas barrier
properties.
[0083] The gas barrier film 3 has the function of blocking gas
(typically oxygen and water vapor) penetration. The gas barrier
film in the invention has excellent gas barrier properties, with an
oxygen permeability of 1 cc/m.sup.2/dayatom or less and a water
vapor permeability of 1 g/m.sup.2/day or less. The reason why the
gas barrier film 3 has such excellent gas barrier properties is
that, since the above-described evaporation source material of the
invention, which is excited more efficiently than a conventional
one, is used in ion plating as a source, the deposited film has
high density, is dense, and is good in adhesive properties.
[0084] The thickness of the gas barrier film 3 is preferably 0.01
.mu.m or more, more preferably 0.02 .mu.m or more. A gas barrier
film 3 with a thickness in the above range is excellent in
impermeability to oxygen and waver vapor, and its oxygen
permeability and water vapor permeability fall in the above
respective ranges. The thickness of the gas barrier film 3 is
preferably 1 .mu.m or less, more preferably 0.2 .mu.m or less. A
gas barrier film 3 with a thickness in the above range causes
decreased bending stress, so that it hardly cracks when the
substrate on which it is deposited is a flexible film, and,
moreover, its gas barrier properties scarcely deteriorate.
Furthermore, since such a gas barrier film can be deposited in a
shorter time, it is easy to increase productivity.
[0085] In the present invention, the expression "the
number-of-atoms ratio is constant along the thickness of the film"
means that the scattering of the number-of-atoms ratios determined
along the thickness of the gas barrier film is within plus or minus
10%, preferably within plus or minus 5%. This range of scattering
is characteristically obtained when the evaporation source material
of the invention is used as a source in ion plating. Namely, the
evaporation source material of the invention is obtained by
compression-molding or granulating the powder mixture prepared by
mixing silicon oxide powder with zinc oxide or tin oxide, a
preferred conductive material powder, so that the gas barrier film
deposited in ion plating using the evaporation source material has
the above-described almost constant number-of-atoms ratio
(scattering: within .+-.10%, preferably within .+-.5%) along the
thickness of the film. The number-of-atoms ratio is herein on a
bulk basis. The surface of the gas barrier film sometimes undergoes
natural oxidation, and the film--substrate interface sometimes
undergoes oxidation due to the gaseous matter emitted from the
substrate. It is considered that the number-of-atoms ratio changes
slightly in either case.
[0086] The number-of-atoms ratio can be obtained from measurements
on an analyzer such as an ESCA. For example, when zinc oxide powder
is used as the conductive material powder, electron spectroscopic
measurement is made using an ESCA, model LAB 220i-XL, manufactured
by VG Scientific Corp., England. A combination of a source of
monochromatic Al X-rays having an Ag-3d-5/2 peak intensity of 300
Kcps to 1 Mcps and a slit with a diameter of about 1 mm was used as
a source of X-rays. Setting a detector on the normal to the sample
surface, measurement was made, and appropriate electrification
corrections were made in the measurements obtained. The data
obtained was analyzed with a software Eclipse version 2.1 contained
in the ESCA, using the peaks corresponding to the binding energies
of Si: 2p, Zn: 2p, C: 1s, and O: 1s. Each peak was subjected to
Shirley background subtraction, and the peak area of each element
was subjected to sensitivity correction (Zn=27.30, Si=0.865, and
O=2.850 for C=1), whereby the number-of-atoms ratio was obtained.
Taking the number of Si atoms as 100, the number of oxygen atoms
and that of zinc atoms were calculated from the number-of-atoms
ratio obtained. Even when the conductive material powder is
composed of other material, e.g., tin oxide, measurement can be
made in a manner almost the same as the above-described one.
[0087] The conductive material can provide the gas barrier film 3
with significantly enhanced gas barrier properties. Especially when
zinc oxide or tin oxide is used, a gas barrier film 3 having higher
density is deposited, so that it is easy to obtain enhanced gas
barrier properties. The gas barrier properties of the gas barrier
film 3 can be evaluated from the wavelength range of infrared
absorption due to Si--O--Si stretching vibration and from the film
density. Specifically, when the gas barrier film 3 is Si--O--Zn
film, the infrared absorption due to Si--O--Si stretching vibration
occurs in the range between 1005 cm.sup.-1 and 1060 cm.sup.-1, and
the density of the film is preferably 2.2 g/cm.sup.3 or more, more
preferably 2.5 g/cm.sup.3 or more, and preferably 2.7 g/cm.sup.3 or
less. When the number-of-atoms ratio in the gas barrier film, the
wavelength range of infrared absorption due to Si--O--Si stretching
vibration, and the film density are in the above respective ranges,
it is easy to ensure denseness for the gas barrier film 3, and the
gas barrier film 3 can exhibit excellent gas barrier properties (an
oxygen permeability of 1 cc/m.sup.2/dayatom or less and a water
vapor permeability of 1 g/m.sup.2/day or less). Moreover, such a
gas barrier film 3 can have flexibility and enhanced
durability.
[0088] In the present invention, the wavelength range of infrared
absorption due to Si--O--Si stretching vibration is determined
using a Fourier transform infrared spectrophotometer, model
Herschel FT-IR-610, manufactured by Nippon Bunko Kabushiki Kaisha,
Japan, equipped with apparatus for multiple reflection (ATR)
measurement. Further, the above-described film density is measured
with an X-ray reflectometer, model ATX-E, manufactured by Rigaku
Denki Kabushiki Kaisha, Japan. Although various apparatus for
measurement can be used to evaluate gas barrier properties, the
above gas barrier properties, i.e., oxygen permeability and water
vapor permeability, were measured with apparatus PARMATRAN 3/31
manufactured by Mocon Corp. under the conditions of 37.8.degree. C.
and 100% RH.
[0089] When the gas barrier sheet of the invention requires
transparency, the substrate 2 is preferably a material having high
transparency. Specifically, gas barrier sheets whose transmission
rates for light of 400-700 nm are 80% or more can be favorably used
for display media, lighting fixtures, covers of solar cells, etc.
that are needed to transmit light, and for packaging materials,
containers, etc. that are needed to be transparent so that their
contents can be seen through them. On the other hand, gas barrier
sheets having light transmission rates of about 50% are good enough
for those objects that are not needed to be transparent and can be
used as ordinary gas barrier sheets for purposes other than the
above-described ones. The term "light transmission rate" is herein
used interchangeably with "total light transmittance". However, the
total light transmittance can be optically adjusted by controlling
film thickness and refractive index, so that this value can be used
as a measure but is not always applicable strictly.
[0090] In FIG. 1, the gas barrier film 3 is formed on one side of
the substrate 2. The present invention, however, is not limited to
this embodiment and encompasses other embodiments. For example, gas
barrier films may be formed on each side of the substrate 2, or a
gas barrier film may be deposited on a resin layer formed on one
side of the substrate 2. Moreover, gas barrier films may be
deposited on resin layers formed on each side of the substrate 2,
and the resin layer and the gas barrier film may be repeatedly
layered two times or more. On the gas barrier film 3, a hard coat
layer, a non-scratching layer, a conductive layer, an
anti-reflection layer, etc. may be formed, as needed. Furthermore,
the gas barrier film 3 may be a multi-layered film.
[0091] On the substrate 2 is deposited the evaporation source
material for use in ion plating, and any substrate can be used in
the present invention. A substrate in sheet or film form is
typically used as the substrate 2, and either a non-flexible or
flexible substrate can be used depending on the intended use or
purpose of the gas barrier sheet finally obtained. Examples of
substrates useful herein include non-flexible substrates such as
glass plates, hard resin boards, wafers, printed circuit boards, a
variety of cards and resin sheets, and flexible substrates made
from polyethylene terephthalate (PET), polyamides, polyolefins,
polyethylene naphthalate (PEN), polycarbonate, polyacrylate,
polymethacrylate, polyurethane acrylate, polyether sulfone,
polyimide, polysilsesquioxanes, polynorbornene, polyether imide,
polyallylates, and cyclic polyolefins. To make a resin-made
substrate 2, the use of a resin capable of withstanding
temperatures of preferably 100.degree. C. or more, more preferably
150.degree. C. or more, is adequate.
[0092] Although the substrate 2 can have any thickness, the
thickness of the substrate is usually made 6 .mu.m or more,
preferably 12 .mu.m or more, and usually 400 .mu.m or less,
preferably 250 .mu.m or less, with consideration for flexibility
and shape retention.
[0093] A resin layer (not shown in the figure) is formed between
the substrate 2 and the gas barrier film 3 in order to increase the
adhesion between them and to enhance gas barrier properties. A
resin layer (not shown in the figure) covering the gas barrier
layer 3 serves as a protective film and provides the gas barrier
sheet with heat resistance, chemical resistance and weathering
resistance. Moreover, even when the gas barrier film 3 has voids,
the voids are filled with the resin layer, so that the gas barrier
film 3 can have excellent gas barrier properties. Examples of such
resin layers useful herein include layers of commercially available
resin materials such as polyamic acid resins, polyethylene resins,
melamine resins, polyurethane resins, polyester resins, polyol
resins, polyurea resins, polyazomethine resins, polycarbonate
resins, polyacrylate resins, polystyrene resins, polyacrylonitrile
(PAN) resins and polyethylene naphthalate (PEN) resins; curable
epoxy resins containing high-molecular-weight epoxy polymers of
bifunctional epoxy resins and bifunctional phenols; and one of, or
two or more of the resin materials used for the substrate. It is
preferable to determine the thickness of the resin layer according
to the material to be used to form the resin layer, and it can be
set to a value between 5 nm and 500 .mu.m, for example.
[0094] In such a resin layer may be incorporated a non-fibrous
inorganic filler with a mean particle diameter of 0.8 to 5 .mu.m.
Examples of non-fibrous inorganic fillers useful herein include
aluminum hydroxide, magnesium hydroxide, talc, alumina, magnesia,
silica, titanium dioxide, and clay. Of these fillers, calcined clay
is particularly preferred. Such an inorganic filler can be
incorporated in the resin layer usually in an amount of 10% by
weight or more, preferably 25% by weight or more, and usually 60%
by weight or less, preferably 45% by weight or less, of the resin
layer.
[0095] According to the gas barrier sheet of the present invention,
there can be obtained a gas barrier sheet having a gas barrier film
whose film quality is uniform along the thickness of the film,
since the gas barrier film has a number-of-atoms ratio constant
along the thickness of the film (scattering: within .+-.10%). More
specifically, there can be obtained a gas barrier sheet having
significantly enhanced gas barrier properties since it has a gas
barrier film having film quality uniform along the thickness of the
film, as well as high density, denseness, and excellent adhesive
properties. The gas barrier sheet of the invention, having the
above advantageous features, can be applied to various objects that
require gas barrier properties. For example, the gas barrier sheet
of the invention can be used as part of materials to be used for
packaging various foods and drinks, chemicals such as adhesives and
pressure-sensitive adhesives, cosmetics, pharmaceuticals, sundry
goods such as chemical self-warmers, and electronic parts. The gas
barrier sheet can also be used for components of liquid crystal
displays. It is particularly preferable to use the gas barrier
sheet in the area of foods because there is an insistent demand for
reduction in the cost of packaging materials in this area.
[0096] (Method of Producing Gas Barrier Sheet)
[0097] A method of the invention, for producing a gas barrier
sheet, comprises the steps of preparing an evaporation source
material for use in ion plating, in a predetermined form, by
compression-molding or granulating a powder mixture comprising 100
parts by weight of silicon oxide powder having a mean particle
diameter of 100 .mu.m or less, preferably 5 .mu.m or less, and 5
parts by weight or more and 100 parts by weight or less of a
conductive material powder having a mean particle diameter of 100
.mu.m or less, preferably 5 .mu.m or less, and depositing a gas
barrier film on a substrate by ion plating using as a source the
evaporation source material.
[0098] In the production method of the invention, the powder
mixture, the evaporation source material and the gas barrier sheet
are the same as those described above. For example, as mentioned
previously, it is preferred that the conductive material be at
least one compound selected from electrically conductive metallic
oxides, nitrides and acid nitrides. Therefore, the powder mixture,
the evaporation source material, and the gas barrier sheet will not
be explained any more. Further, the manner in which the powder
mixture is made into the evaporation source material by compression
molding or granulation is also as explained in the above
description of the method of producing an evaporation source
material, so that it will not be explained any more.
[0099] FIG. 2 is a view showing the structure of an ion-plating
device, and more particularly, it is a view showing the structure
of an ion-plating device of hallow cathode type that was used in
the following Examples. A hollow-cathode-type ion-plating device
101 shown in FIG. 2 comprises a vacuum chamber 102; a feed roll
103a, a wind-up roll 103b and a coating drum 104, which are
situated in the chamber 102; a vacuum exhaust pump 105 connected to
the vacuum chamber 102 by a valve; screens 109, 109; a deposition
chamber 106 separated from the vacuum chamber 102 by the screens
109, 109; a crucible 107 placed in the deposition chamber 106 at
its bottom; an anode magnet 108; a pressure gradient plasma gun 110
situated in a predetermined position on the deposition chamber 106
(in the example shown in the figure, on the right-hand sidewall of
the deposition chamber); a focusing coil 111; a sheeted magnet 112;
a valve 113 for controlling the rate at which argon gas is fed to
the pressure gradient plasma gun 110; a vacuum exhaust pump 114
connected to the deposition chamber 106 by a valve; and a valve 116
for controlling the feed rate of oxygen gas. As shown in the
figure, the feed roll 103a and the wind-up roll 103b are provided
with a reverse mechanism, so that a substrate can be unwound or
wound in either direction.
[0100] Deposition of a gas barrier film, using the ion-plating
device 101, is conducted in the following manner. The vacuum
chamber 102 and the deposition chamber 106 are first evacuated to a
specified vacuum by the vacuum exhaust pumps 105, 114,
respectively, and then oxygen gas is fed to the deposition chamber
106 at a predetermined rate. By manipulating the valve in the line
connecting the vacuum exhaust pump 114 and the deposition chamber
106, the chamber 106 is held at a specified pressure. While letting
a substrate film run, electric power for plasma generation is
supplied to the pressure gradient plasma gun 110 to which argon gas
has been fed at a predetermined rate. A stream of plasma is made to
concentrate at the crucible 107 placed on the anode magnet 108,
thereby vaporizing the evaporation source material. Evaporating
molecules are ionized by the high-density plasma and are deposited
on the substrate to form an intended gas barrier film. In this
manner, a gas barrier sheet is obtained.
[0101] The present invention is characterized in that the
aforementioned evaporation source material of the invention, for
use in ion plating, is used as a source. In ion plating using the
evaporation source material, plasma injected for film deposition
concentrates at the evaporation source material and easily
penetrates into it via the conductive material, causing efficiently
the excitation of the evaporation source material. Consequently,
there is deposited a gas barrier film having significantly enhanced
gas barrier properties.
EXAMPLES
[0102] The present invention will now be described more
specifically by referring to the following Examples. However, these
examples are not intended to limit or restrict the scope of the
invention in any way.
Example 1
[0103] A powder mixture according to the present invention was
obtained by mixing 100 parts by weight of silicon dioxide
(SiO.sub.2) powder (manufactured by Tosoh Silica Corporation,
Japan; mean particle diameter determined by the Coulter Counter
method using apparatus for particle size distribution measurement:
2 .mu.m; specific surface area determined by the nitrogen
adsorption method, using an automatic specific surface area meter
and the BET equation: 800 m.sup.2/g) with 30 parts by weight of
zinc oxide (ZnO) powder (manufactured by Kojundo Kagaku Kabushiki
Kaisha, Japan; mean particle diameter determined by the Coulter
Counter method using apparatus for particle size distribution
measurement: 0.5 .mu.m; volume resistivity measured by the testing
method using a four-point probe array, specified in JIS-K7194: 10
.OMEGA.cm).
[0104] While adding dropwise a 2% aqueous cellulose solution, a
binder, to the powder mixture, the mixture was rolled, thereby
making it into a spherical block with a diameter of 10 mm, which
was placed in an oven at a temperature of 1000.degree. C. for 1
hour. In this manner, there was obtained an evaporating source
material of the invention, for use in ion plating, in the form of a
block with a diameter of 7 mm. Using an X-ray spectroscopic
analyzer (XPS/ESCA), the composition, by weight, of the evaporation
source material obtained was determined. The result was that the
weight ratio of the zinc oxide to the silicon dioxide in the
evaporation source material was 30 to 100. This was nearly equal to
the ratio at which the zinc oxide powder had been initially mixed
with the silicon dioxide powder.
[0105] On the other hand, a plastic film of PEN resin, having a
thickness of 100 .mu.m (Q65 manufactured by Teijin DuPoint Films
Japan Limited, Japan), serving as the transparent film substrate,
was dried in a drier at 160.degree. C. for 1 hour and then set
between the feed roll 103a and the wind-up roll 103b in the
hollow-cathode-type ion-plating device having the structure shown
in FIG. 2.
[0106] Next, after placing the evaporation source material in the
crucible in the ion-plating device, a vacuum was drawn on the
inside of the device. When the vacuum reached 5.times.10.sup.-4 Pa,
argon gas was fed to the plasma gun at a rate of 15 sccm to
generate plasma with a current of 110 A and a voltage of 90V. While
maintaining the inside of the chamber at 1.times.10.sup.-3 Pa, the
magnetic force was exerted to the plasma to bend it to a
predetermined direction, thereby concentrating the plasma at the
evaporation source material. It was confirmed that the evaporation
source material in the crucible was evaporated after it had been
melted. By conducting ion plating for five seconds using as a
source the evaporation source material, a SiO.sub.aZn.sub.b gas
barrier film with a thickness of 30 nm was deposited on the
substrate. The unit "sccm" used herein and also in the following
Examples and Comparative Examples is the abbreviation of standard
cubic centimeter per minute.
[0107] The composition of the gas barrier film was determined using
an ESCA (model LAB 220i-XL, manufactured by VG Scientific Corp.,
England). a and b in SiO.sub.aZn.sub.b were 2.6 and 0.35,
respectively, and the ratio Si:O:Zn was therefore 100:264:35. In
this measurement using the ESCA, a combination of a source of
monochromatic A1 X-rays having an Ag-3d-5/2 peak intensity of 300
Kcps to 1 Mcps and a slit with a diameter of about 1 mm was used as
a source of X-rays. Setting a detector on the normal to the sample
surface, measurement was made, and appropriate electrification
corrections were made in the measurements obtained. The data
obtained was analyzed with a software Eclipse version 2.1 contained
in the ESCA, using the peaks corresponding to the binding energies
of Si: 2p, Zn: 2p, C: 1s, and O: 1s. Each peak was subjected to
Shirley background subtraction, and the peak area of each element
was subjected to sensitivity correction (Zn=27.30, Si=0.865, and
O=2.850 for C=1), whereby the number-of-atoms ratio was obtained.
Taking the number of Si atoms as 1 or 100, the number of oxygen
atoms and that of zinc atoms were calculated from the
number-of-atoms ratio obtained.
[0108] The water vapor permeability, a measure of gas barrier
properties, of the gas barrier film was determined using apparatus
for water vapor permeability measurement (model PERMATRAN-W 3/31,
manufactured by MOCON Corp.) under the conditions of 37.8.degree.
C. and 100% RH; it was 1.4.times.10.sup.-2 g/m.sup.2/day. The
oxygen gas permeability, another measure of gas barrier properties,
of the gas barrier film was determined using apparatus for oxygen
gas permeability measurement (model OX-TRAN 2/20, manufactured by
MOCON Corp.) under the conditions of 23.degree. C. and 90% RH, with
individual zero measurement for background subtraction. The gas
barrier film was found to have an oxygen gas permeability of
3.5.times.10.sup.-1 cc/m.sup.2/dayatom.
Example 2
[0109] A SiO.sub.aZn.sub.b gas barrier film with a thickness of 30
nm was obtained in the same manner as in Example 1, except that the
powder mixture of the invention was prepared by using 15 parts by
weight of the zinc oxide (ZnO) powder for 100 parts by weight of
the silicon dioxide powder. Measurement using the ESCA was made in
the same manner as in Example 1. a and b in SiO.sub.aZn.sub.b were
2.2 and 0.1, respectively, and the ratio Si:O:Zn was therefore
100:224:12. The water vapor permeability and oxygen gas
permeability of the gas barrier film obtained were measured; the
former was 5.6.times.10.sup.-1 g/m.sup.2/day and the latter
6.5.times.10.sup.-1 cc/m.sup.2/day-atom.
Example 3
[0110] A SiO.sub.aZn.sub.b gas barrier film with a thickness of 25
nm was obtained in the same manner as in Example 1, except that the
powder mixture of the invention was prepared by using 70 parts by
weight of the zinc oxide (ZnO) powder for 100 parts by weight of
the silicon dioxide powder. Measurement using the ESCA was made in
the same manner as in Example 1. a and b in SiO.sub.aZn.sub.b were
3.2 and 0.7, respectively, and the ratio Si:O:Zn was therefore
100:321:65. The water vapor permeability and oxygen gas
permeability of the gas barrier film obtained were measured; the
former was 5.0.times.10.sup.-2 g/m.sup.2/day and the latter
2.4.times.10.sup.-1 cc/m.sup.2/dayatom.
Example 4
[0111] A powder mixture according to the invention was prepared by
mixing 100 parts by weight of silicon dioxide (SiO.sub.2) powder
(manufactured by Admatex Kabushiki Kaisha, Japan; mean particle
diameter determined by the Coulter Counter method using apparatus
for particle size distribution measurement: 0.5 .mu.m; specific
surface area obtained by the nitrogen adsorption method, using an
automatic specific surface area meter and the BET equation: 6.8
m.sup.2/g) with 30 parts by weight of tin oxide (SnO) powder.
[0112] While adding dropwise a 3% aqueous cellulose solution, a
binder, to the powder mixture, the mixture was rolled, followed by
stirring one over night. Thereafter, the mixture was dried and then
powdered in a mortar. Subsequently, the powder was placed in a 62
mm-square metal mold and was press-molded with a pressure of 0.2
t/cm.sup.2. The press-molded product was vacuum-packaged and then
compression-molded with a pressure of 1.3 t/cm.sup.2 using a CI
press process. The compression-molded product was placed in an oven
at 500.degree. C. for 24 hours, thereby obtaining an evaporation
source material of the invention, for use in ion plating, in the
form of a 50 mm-square block. Using an X-ray spectroscopic analyzer
(XPS/ESCA), the composition, by weight, of the evaporation source
material obtained was determined. The result was that the weight
ratio of the tin oxide to the silicon dioxide in the evaporation
source material was 30 to 100. This was nearly equal to the ratio
at which the tin oxide powder had been initially mixed with the
silicon dioxide powder.
[0113] On the other hand, using, as the transparent film substrate,
a PEN resin film with a thickness of 100 .mu.m (Q65 manufactured by
Teijin DuPoint Films Japan Limited, Japan) that had been dried in a
drier at 160.degree. C. for 1 hour, ion plating was conducted in
the same manner as in Example 1. In this manner, there was obtained
a SiO.sub.aSn.sub.b gas barrier film deposited on the
substrate.
[0114] The composition of the gas barrier film was determined using
an ESCA (model LAB 220i-XL, manufactured by VG Scientific Corp.,
England). It was found that the ratio Si:O:Sn was 100:202:14. The
thickness of the gas barrier film was 93 nm.
[0115] The water vapor permeability, a measure of gas barrier
properties, of the gas barrier film was determined using apparatus
for water vapor permeability measurement (model PERMATRAN-W 3/31,
manufactured by MOCON Corp.) under the conditions of 37.8.degree.
C. and 100% RH; it was 1.2.times.10.sup.-2 g/m.sup.2/day. The
oxygen gas permeability, another measure of gas barrier properties,
of the gas barrier film was also determined using apparatus for
oxygen gas permeability measurement (model OX-TRAN 2/20,
manufactured by MOCON Corp.) under the conditions of 23.degree. C.
and 90% RH, with individual zero measurement for background
subtraction. The gas barrier film was found to have an oxygen gas
permeability of 2.2.times.10.sup.-1 cc/m.sup.2/dayatom.
Example 5
[0116] A SiO.sub.aSn.sub.b gas barrier film was obtained in the
same manner as in Example 4, except that the powder mixture of the
invention was prepared by using 60 parts by weight of the tin oxide
(SnO) powder for 100 parts by weight of the silicon dioxide powder.
Measurement using the ESCA was made in the same manner as in
Example 4. It was found that the composition (Si:O:Sn) of the gas
barrier film was 100:232:26. The thickness of the gas barrier film
was 87 nm. Further, the water vapor permeability and oxygen gas
permeability of the gas barrier film formed were measured; the
former was 0.9.times.10.sup.-2 g/m.sup.2/day and the latter
1.9.times.10.sup.-2 cc/m.sup.2/dayatom.
Example 6
[0117] A powder mixture according to the invention was prepared by
mixing 100 parts by weight of silicon dioxide (SiO.sub.2) powder
(manufactured by Admatex Kabushiki Kaisha, Japan; mean particle
diameter determined by the Coulter Counter method using apparatus
for particle size distribution measurement: 0.5 .mu.m; specific
surface area obtained by the nitrogen adsorption method using an
automatic specific surface area meter and the BET equation: 6.8
m.sup.2/g) with 30 parts by weight of metallic tin (Sn) powder
(manufactured by Kojundo Kagaku Kabushiki Kaisha, Japan, mean
particle diameter: 63 .mu.m).
[0118] While adding dropwise a 3% aqueous cellulose solution, a
binder, to the powder mixture, the mixture was rolled, followed by
stirring one over night. The mixture was dried and then powdered in
a mortar. Subsequently, the powder was placed in a 62 mm-square
metal mold and was press-molded with a pressure of 0.2 t/cm.sup.2.
The press-molded product was vacuum-packaged and then
compression-molded with a pressure of 1.3 t/cm.sup.2 using a CI
press process. The compression-molded product was placed in an oven
at 500.degree. C. for 24 hours, thereby obtaining an evaporation
source material of the invention, for use in ion plating, in the
form of a 50 mm-square block.
[0119] On the other hand, using, as the transparent film substrate,
a PEN resin film with a thickness of 100 .mu.m (Q65 manufactured by
Teijin DuPoint Films Japan Limited, Japan) that had been dried in a
drier at 160.degree. C. for 1 hour, ion plating was conducted in
the same manner as in Example 1. In this manner, there was obtained
a SiO.sub.aSn.sub.b gas barrier film deposited on the
substrate.
[0120] The composition of the gas barrier film was determined using
an ESCA (model LAB 220i-XL, manufactured by VG Scientific Corp.,
England). It was found that the ratio Si:O:Sn was 100:155:21. The
thickness of the gas barrier film was 74 nm.
[0121] The water vapor permeability, a measure of gas barrier
properties, of the gas barrier film was determined using apparatus
for water vapor permeability measurement (model PERMATRAN-W 3/31,
manufactured by MOCON Corp.) under the conditions of 37.8.degree.
C. and 100% RH; it was 1.4.times.10.sup.-2 g/m.sup.2/day. The
oxygen gas permeability, another measure of gas barrier properties,
of the gas barrier film was also determined using apparatus for
oxygen gas permeability measurement (model OX-TRAN 2/20,
manufactured by MOCON Corp.) under the conditions of 23.degree. C.
and 90% RH, with individual zero measurement for background
subtraction. The gas barrier film was found to have an oxygen gas
permeability of 1.8.times.10.sup.-2 cc/m.sup.2/dayatom.
Comparative Example 1
[0122] A SiO.sub.cZn.sub.d gas barrier film with a thickness of 32
nm was obtained in the same manner as in Example 1, except that the
powder mixture was prepared by using 3 parts by weight of the zinc
oxide powder, serving as the conductive material powder, for 100
parts by weight of the silicon dioxide powder. Measurement using
the ESCA was made in the same manner as in Example 1. c and d in
SiO.sub.cZn.sub.d were 2.1 and 0.04, respectively, and the ratio
Si:O:Zn was therefore 100:205:4. The water vapor permeability
oxygen and oxygen gas permeability of the gas barrier film were
measured; the former was 2.5 g/m.sup.2/day and the latter 2.5
cc/m.sup.2/dayatom.
Comparative Example 2
[0123] A SiO.sub.e gas barrier film with a thickness of 35 nm was
obtained in the same manner as in Example 1, except that the zinc
oxide powder, a conductive material powder, was not used.
Measurement using the ESCA was made in the same manner as in
Example 1. e in SiO.sub.e was 2.2. The water vapor permeability
oxygen and oxygen gas permeability of the gas barrier film were
measured; the former was 2.5 g/m.sup.2/day and the latter 2.7
cc/m.sup.2/dayatom.
* * * * *