U.S. patent number RE37,446 [Application Number 08/853,953] was granted by the patent office on 2001-11-13 for low emissivity film.
This patent grant is currently assigned to Asahi Glass Company Ltd.. Invention is credited to Eiichi Ando, Masami Miyazaki.
United States Patent |
RE37,446 |
Miyazaki , et al. |
November 13, 2001 |
Low emissivity film
Abstract
A low emissivity film which comprises: a substrate; and a
coating of oxide and metallic films alternately formed on the
substrate in a total of (2n+1) layers where n is an integer being
equal to or more than 1, with the innermost layer being an oxide
film, wherein the oxide film (B) formed on the outer side of the
metallic film (A) being most apart from the substrate, has an
internal stress which is equal to, or less than 1.1.times.10.sup.10
dyne/cm.sup.2.
Inventors: |
Miyazaki; Masami (Ebina,
JP), Ando; Eiichi (Yokohama, JP) |
Assignee: |
Asahi Glass Company Ltd.
(Tokyo, JP)
|
Family
ID: |
26497260 |
Appl.
No.: |
08/853,953 |
Filed: |
May 9, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
726263 |
Jul 5, 1991 |
05413864 |
May 9, 1995 |
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Foreign Application Priority Data
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Jul 5, 1990 [JP] |
|
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2-176282 |
Nov 27, 1990 [JP] |
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2-321273 |
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Current U.S.
Class: |
428/432; 359/350;
359/360; 359/577; 359/580; 359/581; 359/582; 359/585; 359/586;
428/212; 428/426; 428/469; 428/472; 428/697; 428/699; 428/701;
428/702 |
Current CPC
Class: |
C03C
17/36 (20130101); C03C 17/3613 (20130101); C03C
17/3618 (20130101); C03C 17/3639 (20130101); C03C
17/3644 (20130101); C03C 17/366 (20130101); C03C
17/3676 (20130101); C03C 17/3681 (20130101); C23C
14/086 (20130101); C23C 14/18 (20130101); C03C
2217/78 (20130101); Y10T 428/24942 (20150115) |
Current International
Class: |
C03C
17/36 (20060101); C23C 14/08 (20060101); B32B
015/04 () |
Field of
Search: |
;428/697,699,701,432,426,469,472,212,702
;359/350,360,577,580,581,582,585,586 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0183052 |
|
Oct 1985 |
|
EP |
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0332717 |
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Mar 1988 |
|
EP |
|
2586245 |
|
Feb 1987 |
|
FR |
|
Other References
World Patent Index Latest Accession No. 84-059802, week 10, Derwent
Publications Ltd. London, GB & JP-A-59 018 134, (Asahi Glass
KK), Jan. 1984.* .
World Patent Index Lastest Accession No. 89-003563, week 01,
Derwent Publcations Ltd., London, GB & JP-A-63-281-204 (Sharp
KK) Nov. 17, 1988.* .
Cotton et al, "Advanced Inorganic Chemistry", 4th ed., Wiley New
York, p. 598, 1980..
|
Primary Examiner: Turner; Archene
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, P.C.
Claims
We claim: .[.
1. A low emissivity film which comprises:
a substrate; and
a coating of an oxide of zinc or tin and metallic films alternately
formed on the substrate in a total of (2n+1) layers where n is an
integer being equal to or more than 1, with the layer closest to
the substrate being an oxide film, wherein the oxide film (B)
formed on the outer side of the metallic film (A) being most remote
from the substrate, has an internal stress which is equal to, or
less than 1.1.times.10.sup.10 dyne/cm.sup.2 and is doped with at
least one dopant selected from the group consisting of Al, Si, B,
Ti, Sn, Mg and Cr, said oxide film (B) having a thickness of 200 to
700 .ANG. and said metallic film having a thickness of 50 to 150
.ANG...]. .[.
2. The low emissivity film according to claim 1, wherein at least
one layer of the oxide film except the oxide film (B) has an
internal stress, whose value is equal to or less than
1.1.times.10.sup.10 dyne/cm.sup.2..]..[.
3. The low emissivity film according to claim 1, wherein the oxide
of the oxide film most remote from the substrate of zinc or tin is
doped with at least one dopant selected from the group consisting
of Al, Si, B, Ti, Sn, Mg and Cr in an amount of at most 10% atomic
ratio based on the total amount of metal present..]..[.
4. The low emissivity film according to claim 1, wherein the oxide
film (B) is a multi-layer film comprising at least two layers,
having a film layer which has an internal stress, whose value is
equal to or less than 7.0.times.10.sup.9 dyne/cm.sup.2 and whose
major component is tin oxide..]..[.
5. The low emissivity film according to claim 4, wherein the oxide
film layer (B) is a multi-layer film layer having at least a film
whose major component is zinc oxide, and a film having an internal
stress, whose value is equal to or less than 7.0.times.10.sup.9
dyne/cm.sup.2, and whose major component is tin oxide..]..[.
6. The low emissivity film according to claim 1, wherein the oxide
film (B) is composed of a single layer or a multi-layer, having at
least a layer of which major component is zinc oxide..]..[.
7. The low emissivity film according to claim 6, wherein the layer
of said oxide film (B) most remote from the substrate comprises a
layer for controlling adhesive strength thereof with a plastic
intermediate film for lamination with another substrate..]..[.
8. The low emissivity film according to claim 6, wherein the
crystal structure of said zinc oxide is hexagonal, and the value of
the diffraction angle 2.theta. (center of gravity position) of
(002) diffraction line of the hexagonal zinc oxide in X-ray
diffraction method using CuK.alpha. radiation, is not smaller than
33.88.degree. and not larger than 35.00.degree...]..[.
9. The low emissivity film according to claim 8, wherein the value
of the diffraction angle 2.theta. (center of gravity position) of
(002) diffraction line of the hexagonal zinc oxide in X-ray
diffraction method using CuK.alpha. radiation, is not smaller than
34.00.degree. and not larger than 34.88.degree...]..[.
10. A low emissivity film which comprises:
a substrate; and
a coating of an oxide of zinc or tin and metallic films alternately
formed on the substrate in a total of (2n+1) layers where n is an
integer being equal to or more than 1, with a layer thereof closest
to the substrate being an oxide film,
wherein the oxide film (B) formed on the side of the metallic film
(A) being most remote from the substrate, is a single layer film or
a multi-layer film having at least a film whose major component is
hexagonal zinc oxide and is doped with at least one dopant selected
from the group consisting of Al, Si, B, Ti, Sn, Mg and Cr; and
the value of the diffraction angle 2.theta. (center of gravity
position) or (002) diffraction line of the hexagonal zinc oxide of
the low emissivity film in X-ray diffraction method using
CuK.alpha. radiation, is not smaller than 33.88.degree. and not
larger than 35.00.degree. wherein said oxide film (B) has a
thickness of 200 to 700 .ANG. and said metallic film has a
thickness of 50 to 150 .ANG...]. .[.
11. The low emissivity film according to claim 10, wherein the
oxide of the oxide film most remote from the substrate of zinc or
tin is doped with at least one dopant selected from the group
consisting of Al, Si, B, Ti, Sn, Mg and Cr in an amount of at most
10% atomic ratio based on the total amount of metal
present..]..[.
12. The low emissivity film according to claim 10, wherein the
layer of said oxide film (B) most remote from the substrate
comprises a layer for controlling adhesive strength thereof with a
plastic intermediate film for lamination with another
substrate..]..[.
13. The low emissivity film according to claim 10, wherein the
value of the diffraction angle 2.theta. (center of gravity
position) of (002) diffraction line of the hexagonal zinc oxide in
x-ray diffraction method using CuK.alpha. radiation is not smaller
than 34.00.degree. and not larger than 34.88.degree...]..[.
14. The low emissivity film according to claim 10, wherein the
metallic film (A) is a metallic film whose major component is
Ag..]..[.
15. A low emissivity film which comprises:
a substrate; and
a coating of an oxide of zinc or tin and metallic films alternately
formed on the substrate in a total of (2n+1) layers where n is an
integer being equal to or more than 1, with the layer closest to
the substrate being an oxide film,
wherein the oxide film (B) formed on the side of the metallic film
(a) being most remote from the substrate is a multi-layer and is
doped with at least one dopant selected from the group consisting
of Al, Si, B, Ti, Sn, Mg and Cr, comprising at least three layers
in which a single layer or a plurality of layers, the major
component thereof being zinc oxide and a single layer or a
plurality of layers, the major component thereof being tin oxide,
are alternatively formed, said oxide film (B) having a thickness of
200 to 700 .ANG. and said metallic film having a thickness of 50 to
150 .ANG., wherein the oxide film (B) formed on the side of the
metallic film (A) being most remote from the substrate has an
internal stress which is equal to, or less than 1.1.times.10.sup.10
dyne/cm.sup.2..]. .[.
16. The low emissivity film according to claim 15, wherein the
oxide of the oxide film most remote from the substrate of zinc or
tin is doped with at least one dopant selected from the group
consisting of Al, Si, B, Ti, Sn, Mg and Cr in an amount of at most
10% atomic ratio based on the total amount of metal
present..]..[.
17. The low emissivity film according to claim 15, wherein the
crystal structure of said zinc oxide is hexagonal, and the value of
the diffraction angle 2.theta. (center of gravity position) of
(002) diffraction line of the hexagonal zinc oxide in X-ray
diffraction method using CuK.alpha. radiation, is not smaller than
33.88.degree. and not larger than 35.00.degree...]..[.
18. The low emissivity film according to claim 15, wherein the
metallic film (A) is a metallic film whose major component is
Ag..]..[.
19. The low emissivity film according to claim 15, wherein the
oxide film (B) has a multi-layer film comprising three layers or
five layers in which a plurality of layers, the major component
thereof being zinc oxide (C), and a single layer or a plurality of
layers, the major component thereof tin oxide (D), are
alternatively laminated in an order of (C) layer, (D) layer, and
(C) layer..]..[.
20. The low emissivity film according to claim 15, wherein the
oxide film (B) has a multi-layer film comprising three layers or
five layers in which a single layer or a plurality of layers whose
major component is zinc oxide (E), and a plurality of layers whose
major component is tin oxide (F), are alternatively laminated in an
order of (F) layer, (E) layer, and (F) layer..]..[.
21. The low emissivity film according to claim 15, wherein at least
one layer of the oxide films except the oxide film (B) is a
multi-layer film having at least a layer whose major component is
zinc oxide and a layer whose major component is tin
oxide..]..[.
22. A low emissivity film which comprises:
a substrate; and
a coating of an oxide of zinc or tin and metallic films alternately
formed on the substrate in a total of (2n+1) layers where n is an
integer being equal to or more than 1, with the layer closest to
the substrate being an oxide film,
wherein the oxide film (B) being most remote from the substrate is
composed of a multi-layer having at least one layer of which major
component is zinc oxide, at least one of said layer whose major
component is zinc oxide being doped with at least one dopant
selected from the group consisting of Al, Si, B, Ti, Sn, Mg and Cr,
said oxide film (B) comprising at least three layers in which a
single layer or a plurality of layers, the major component thereof
being zinc oxide and a single layer or a plurality of layers, the
major component thereof being tin oxide, are alternatively formed,
said oxide film (B) having a thickness of 200 to 700 .ANG. and said
metallic film having a thickness of 50 to 150 .ANG., wherein the
layer of the oxide film (B) formed on the side of the metallic film
(A) being most remote from the substrate whose major component is
zinc oxide has an internal stress which is equal to, or less than
1.1.times.10.sup.10 dyne/cm.sup.2 and
wherein the layer of said oxide film (B) most remote from the
substrate comprises a layer for controlling adhesive strength
thereof with a plastic intermediate film for lamination with
another substrate..]. .Iadd.
23. A low emissivity film which comprises:
a substrate; and
a coating of an oxide of zinc or tin and metallic films alternately
formed on the substrate in a total of (2n+1) layers where n is an
integer being equal to or more than 1, with the layer closest to
the substrate being an oxide film,
wherein the oxide film (B) formed on the side of the metallic film
(a) being most remote from the substrate is a multi-layer,
comprising at least three layers, each layer of which comprises
zinc oxide or tin oxide, alternatively formed, said oxide film (B)
having a thickness of 200 to 700 .ANG. and said metallic film
having a thickness of 50 to 150 .ANG., wherein the crystal
structure of said zinc oxide is hexagonal, and the value of the
diffraction angle 2.theta. (center of gravity position) of (002)
diffraction line of the hexagonal zinc oxide in X-ray diffraction
method using CuK.alpha. radiation, is not smaller than
33.88.degree. and not larger than 35.00.degree...Iaddend..Iadd.
24. The low emissivity film according to claim 23, wherein the
oxide of the zinc oxide film most remote from the substrate is
doped with at least one dopant selected from the group consisting
of Al, Si, B, Ti, Sn, Mg and Cr in an amount of at most 10% atomic
ratio based on the total amount of metal
present..Iaddend..Iadd.
25. The low emissivity film according to claim 23, wherein the
metallic film (A) is a metallic film whose major component is
Ag..Iaddend..Iadd.
26. The low emissivity film according to claim 23, wherein the
oxide film (B) has a multi-layer film comprising three layers or
five layers in which a plurality of layers, the major component
thereof being zinc oxide (C), and a single layer or a plurality of
layers, the major component thereof being tin oxide (D), are
alternatively laminated in an order of (C) layer, (D) layer, and
(C) layer..Iaddend..Iadd.
27. The low emissivity film according to claim 23, wherein the
oxide film (B) has a multi-layer film comprising three layers or
five layers in which a single layer or a plurality of layers whose
major component is zinc oxide (E), and a plurality of layers whose
major component is tin oxide (F), are alternatively laminated in an
order of (F) layer, (E) layer, and (F) layer..Iaddend..Iadd.
28. The low emissivity film according to claim 23, wherein at least
one layer of the oxide films except the oxide film (B) is a
multi-layer film having at least a layer whose major component is
zinc oxide and a layer whose major component is tin
oxide..Iaddend..Iadd.
29. The low emissivity film according to claim 23, wherein said
oxide film (B) comprises three layers, wherein the three layers
comprise, respectively, ZnO/SnO.sub.2 /ZnO..Iaddend..Iadd.
30. The low emissivity film according to claim 23, wherein said
oxide film (B) comprises three layers, wherein the three layers
comprise, respectively, SnO.sub.2
/ZnO/SnO.sub.2..Iaddend..Iadd.
31. The low emissivity film according to claim 23, wherein said
oxide film (B) is doped with at least one dopant selected from the
group consisting of Al, Si, B, Ti, Sn, Mg and
Cr..Iaddend..Iadd.
32. The low emissivity film according to claim 23, wherein said
oxide film (B) formed on the side of the metallic film (A) being
most remote from the substrate has an internal stress which is
equal to or less than 1.1.times.10.sup.10
dyne/cm.sup.2..Iaddend..Iadd.
33. A low emissivity film which comprises:
a substrate; and
a coating of an oxide of zinc or tin and metallic films alternately
formed on the substrate in a total of (2n+1) layers where n is an
integer being equal to or more than 1, with the layer closest to
the substrate being an oxide film,
wherein the oxide film (B) formed on the side of the metallic film
(a) being most remote from the substrate is a multi-layer,
comprising at least three layers, each layer of which comprises
zinc oxide or tin oxide, alternatively formed, said oxide film (B)
having a thickness of 200 to 700 .ANG. and said metallic film
having a thickness of 50 to 150 .ANG., wherein said oxide film (B)
formed on the side of the metallic film (A) being most remote from
the substrate has an internal stress which is equal to or less than
1.1.times.10.sup.10 dyne/cm.sup.2..Iaddend..Iadd.
34. The low emissivity film according to claim 33, wherein the
oxide of the zinc oxide film most remote from the substrate is
doped with at least one dopant selected from the group consisting
of Al, Si, B, Ti, Sn, Mg and Cr in an amount of at most 10% atomic
ratio based on the total amount of metal
present..Iaddend..Iadd.
35. The low emissivity film according to claim 33, wherein the
metallic film (A) is a metallic film whose major component is
Ag..Iaddend..Iadd.
36. The low emissivity film according to claim 33, wherein the
oxide film (B) has a multi-layer film comprising three layers or
five layers in which a plurality of layers, the major component
thereof being zinc oxide (C), and a single layer or a plurality of
layers, the major component thereof being tin oxide (D), are
alternatively laminated in an order of (C) layer, (D) layer, and
(C) layer..Iaddend..Iadd.
37. The low emissivity film according to claim 33, wherein the
oxide film (B) has a multi-layer film comprising three layers or
five layers in which a single layer or a plurality of layers whose
major component is zinc oxide (E), and a plurality of layers whose
major component is tin oxide (F), are alternatively laminated in an
order of (F) layer, (E) layer, and (F) layer..Iaddend..Iadd.
38. The low emissivity film according to claim 33, wherein at least
one layer of the oxide films except the oxide film (B) is a
multi-layer film having at least a layer whose major component is
zinc oxide and a layer whose major component is tin
oxide..Iaddend..Iadd.
39. The low emissivity film according to claim 33, wherein said
oxide film (B) comprises three layers, wherein the three layers
comprise, respectively, ZnO/SnO.sub.2 /ZnO..Iaddend..Iadd.
40. The low emissivity film according to claim 33, wherein said
oxide film (B) comprises three layers, wherein the three layers
comprise, respectively, SnO.sub.2
/ZnO/SnO.sub.2..Iaddend..Iadd.
41. The low emissivity film according to claim 33, wherein said
oxide film (B) is doped with at least one dopant selected from the
group consisting of Al, Si, B, Ti, Sn, Mg and
Cr..Iaddend..Iadd.
42. A low emissivity film which comprises:
a substrate; and
a coating of an oxide of zinc or tin and metallic films alternately
formed on the substrate in a total of (2n+1) layers where n is an
integer being equal to or more than 1, with the layer closest to
the substrate being an oxide film,
wherein the oxide film (B) being most remote from the substrate is
composed of a multi-layer, said oxide film (B) comprising at least
three layers, each layer of which comprises zinc oxide or tin
oxide, alternatively formed, said oxide film (B) having a thickness
of 200 to 700 .ANG. and said metallic film having a thickness of 50
to 150 .ANG.,
wherein the layer of said oxide film (B) most remote from the
substrate comprises a layer for controlling adhesive strength
thereof with a plastic intermediate film for lamination with
another substrate,
wherein said oxide film (B) formed on the side of the metallic film
(A) being most remote from the substrate has an internal stress
which is equal to or less than 1.1.times.10.sup.10
dyne/cm.sup.2..Iaddend..Iadd.
43. The low emissivity film according to claim 42, wherein said
multilayer has at least one layer of which major component is zinc
oxide, at least one of said layer whose major component is zinc
oxide being doped with at least one dopant selected from the group
consisting of Al, Si, B, Ti, Sn, Mg and Cr..Iaddend..Iadd.
44. A low emissivity film which comprises:
a substrate; and
a coating of an oxide of zinc or tin and metallic films alternately
formed on the substrate in a total of (2n+1) layers where n is an
integer being equal to or more than 1, with the layer closest to
the substrate being an oxide film,
wherein the oxide film (B) formed on the side of the metallic film
(a) being most remote from the substrate is a multi-layer,
comprising at least three layers, each layer of which comprises
zinc oxide or tin oxide, alternatively formed, said oxide film (B)
having a thickness of 200 to 700 .ANG. and said metallic film
having a thickness of 50 to 150 .ANG.,
wherein said oxide film (B) comprises three layers, wherein the
three layers comprise, respectively, ZnO/SnO.sub.2
/ZnO..Iaddend..Iadd.
45. The low emissivity film according to claim 44, wherein the
oxide of the zinc oxide film most remote from the substrate is
doped with at least one dopant selected from the group consisting
of Al, Si, B, Ti, Sn, Mg and Cr in an amount of at most 10% atomic
ratio based on the total amount of metal
present..Iaddend..Iadd.
46. The low emissivity film according to claim 44, wherein the
metallic film (A) is a metallic film whose major component is
Ag..Iaddend..Iadd.
47. The low emissivity film according to claim 44, wherein said
oxide film (B) is doped with at least one dopant selected from the
group consisting of Al, Si, B, Ti, Sn, Mg and
Cr..Iaddend..Iadd.
48. A low emissivity film which comprises:
a substrate; and
a coating of an oxide of zinc or tin and metallic films alternately
formed on the substrate in a total of (2n+1) layers where n is an
integer being equal to or more than 1, with the layer closest to
the substrate being an oxide film,
wherein the oxide film (B) formed on the side of the metallic film
(a) being most remote from the substrate is a multi-layer,
comprising at least three layers, each layer of which comprises
zinc oxide or tin oxide, alternatively formed, said oxide film (B)
having a thickness of 200 to 700 .ANG. and said metallic film
having a thickness of 50 to 150 .ANG.,
wherein said oxide film (B) comprises three layers, wherein the
three layers comprise, respectively, SnO.sub.2
/ZnO/SnO.sub.2..Iaddend..Iadd.
49. The low emissivity film according to claim 48, wherein the
oxide of the zinc oxide film most remote from the substrate is
doped with at least one dopant selected from the group consisting
of Al, Si, B, Ti, Sn, Mg and Cr in an amount of at most 10% atomic
ratio based on the total amount of metal
present..Iaddend..Iadd.
50. The low emissivity film according to claim 48, wherein the
metallic film (A) is a metallic film whose major component is
Ag..Iaddend..Iadd.
51. The low emissivity film according to claim 48, wherein said
oxide film (B) is doped with at least one dopant selected from the
group consisting of Al, Si, B, Ti, Sn, Mg and Cr..Iaddend.
Description
This invention relates to a low emissivity film which is excellent
in durability, especially in moisture resistance or in acid
resistance.
A film composed of (2n+1) layers (n.gtoreq.1) such as a film
composed of three layers in which an oxide film, an Ag film, and an
oxide film are successively coated on a surface of a substrate, or
a film composed of five layers in which an oxide film, an Ag film,
an oxide film, an Ag film, and an oxide film are successively
coated on a surface of a substrate, is a heat reflective film
called Low-E (Low-Emissivity) film. A glass in which such a Low-E
film is formed, is called a Low-E glass. This glass can prevent
lowering of room temperature by reflecting the thermal infrared
radiation emitted from within the heated room, it being used mainly
in cold district on the climates for a decreasing heating load.
Furthermore, since this glass has a heat insulating effect of solar
radiation energy, it can be used in a windshield of an automobile.
Since this glass is transparent and is electrically conductive, it
has a use as an electromagnetic shielding glass. When this glass is
equipped with an electric heating such as a bus bar composed of an
electrically conductive printing or the like, this glass can be
used as an electrically heated window.
As a major Low-E glass, such a glass is exemplified by having a
film composition of ZnO/Ag/ZnO/glass. However, since this film is
devoid of durability such as anti-scratching property or chemical
stability, it can not be used on a single plate, and it is
necessary to use the film in a laminated glass or in double
glazing. This film has a problem especially in moisture resistance,
in which white dot or white turbidity is caused by moisture in the
air or by moisture contained in an intermediate film in case of the
laminated glass. Furthermore, since ZnO is insufficient in acid
resistance, the film may be deteriorated by acid substance in the
air. Due to these shortcomings, caution is required in the storage
or in the handling of the single plate.
It is an object of the present invention to provide a Low-E film
capable of overcoming the above shortcomings, and excellent in
durability, especially in moisture resistance or in acid
resistance.
According to the first aspect of the present invention, there is
provided a low emissivity film which comprises:
a substrate; and
a coating of oxide and metallic films alternately formed on the
substrate in a total of (2n+1) layers where n is an integer being
equal to or more than 1, with the innermost layer being an oxide
film,
wherein the oxide film (B) formed on the outer side of the metallic
film (A) being most apart from the substrate, has an internal
stress which is equal to, or less than 1.1.times.10.sup.10
dyne/cm.sup.2.
According to the second another aspect of the present invention,
there is provided a low emissivity film which comprises:
a substrate; and
a coating of oxide and metallic films alternately formed on the
substrate in a total of (2n+1) layers where n is an integer being
equal to or more than 1, with the innermost layer being an oxide
film,
wherein the oxide film (B) formed on the outer side of the metallic
film (A) being mostly apart from the substrate, is a single layer
film or a multi-layer film having at least a film whose major
component is hexagonal zinc oxide; and
a value of a diffraction angle 2.theta. (center of gravity
position) of (002) diffraction line of the hexagonal zinc oxide of
the low emissivity film in X-ray diffraction method using
CuK.alpha. radiation is not smaller than 33.88.degree. and not
larger than 35.00.degree..
According to the third aspect of the present invention, there is
provided a low emissivity film which comprises:
a substrate; and
a coating of oxide and metallic films alternately formed on the
substrate in a total of (2n+1) layers where n is an integer being
equal to or more than 1, with the innermost layer being an oxide
film,
wherein the oxide film (B) formed on the outer side of the metallic
film (A) being most apart from the substrate, is a multi-layer film
having at least a layer whose major component is zinc oxide and a
layer whose major component is tin oxide.
In the drawings:
FIGS. 1a and 1b are sectional diagrams showing embodiments of Low-E
glasses on which low emissivity films are formed, according to the
present invention. The oxide film (B) according to the first and
second aspects of the invention are as follows.
As mentioned above, in case of the conventional Low-E glass (film
composition: ZnO/Ag/ZnO/glass), when it is left in a room, white
turbidity or white dot appears on the film due to the moisture in
the air.
When the film with white turbidity or white dot is observed by a
scanning electron microscope (SEM), the existence of cracks or
wrinkles, and exfoliation of the film are recognized on the surface
of the film.
When an elementary analysis is performed on the exfoliated part of
this film, with respect to Ag and Zn, Ag is found to exist in a
certain amount irrespective of the existence of the exfoliation. On
the contrary, the detected amount of Zn is halved at the exfoliated
part. Accordingly, the exfoliation is found to take place on the
interface between the uppermost layer of ZnO and the Ag layer.
Samples before and after a moisture resistance test (the samples
are left for 6 days, at 50.degree. C., in an atmosphere of relative
humidity of 95%) were examined by an X-ray diffraction method. The
diffraction angle 2.theta. (center of gravity position of peak),
interplanar spacing d, and the peak width (integral width) I.W.
with respect to (002) diffraction line of hexagonal zinc oxide, and
(111) diffraction line of cubic Ag, are respectively shown in Table
1.
It is possible to detect the degree of strain of the lattice due to
an internal stress, by the deviation of peaks in the X-ray
diffraction method. In case of the sample of
ZnO(b)/Ag/ZnO(a)/glass, the peak of ZnO(b) of the uppermost layer,
is detected with an intensity 5 to 15 times as much as the peak of
ZnO(a). Therefore, the peak of ZnO by the X-ray diffraction method
with respect to the total of the sample, is considered to be the
peak of hexagonal ZnO(b) of the uppermost layer, although ZnO(a)
may more or less influence it.
TABLE 1 ZnO (002) Ag (111) Before After Before After moisture
moisture moisture moisture resistance resistance resistance
resistance test test test test 2.theta. (deg.) 33.78 33.91 38.09
38.09 d (.ANG.) 2.650 2.641 2.361 2.361 1 .multidot. w (deg.) 0.510
0.623 0.977 0.675
According to Table 1, (002) diffraction line of ZnO in the Low-E
film before the moisture resistance test, deviates in its position,
compared with 2.theta.=34.44.degree. of ZnO powder. This suggests
the existence of a lattice strain. This lattice strain is due to an
internal stress of the film. In the samples before the moisture
resistance test, the interplanar space d.sub.002 =2.650 .ANG.,
which is larger than d.sub.002 =2.602 .ANG. of ZnO powder by 1.8%.
From this result, the film is found to receive a considerably large
compressive stress. In case of samples after the moisture
resistance test, the lattice strain is more or less decreased, as
d.sub.002 =2.641 .ANG.. This test result corresponds with the fact
in which the internal stress of ZnO at the uppermost layer is
partly relieved by the cracks, the wrinkles, and the
exfoliation.
Concerning the (111) diffraction line of Ag, the peak width after
the moisture resistance test is decreased. Therefore grain growth
of Ag is considered to take place by performing the moisture
resistance test.
Accordingly, mechanism of generation of the white turbidity or
white dots, is considered as follows. The hexagonal ZnO film at the
uppermost layer can not resist the large internal stress. The film
is exfoliated from the interface with Ag film, and is destroyed.
Next grain size of Ag is increased. The film displays white
turbidity or white dot since light is scattered by the destroyed
surface and by the large silver grain. In the examples of Table 1,
the internal stress is a compressive stress. However there are two
kinds of internal stress, that is, a compressive stress and the
tensile stress, both of which cause destruction of the film.
From the above observation, in this invention, it is found that the
decrease of the internal stress of ZnO film at the upper most
layer, is effective to prevent the white turbidity or white dots
due to moisture.
FIGS. 1a and 1b are sectional diagrams showing embodiments of low
emissivity films according to the present invention. FIG. 1a is a
sectional diagram of the low emissivity film composed of three
layers, and FIG. 1b is a sectional diagram of the low emissivity
film composed of (2n+1) layers. Reference numeral 1 designates a
substrate, 2, an oxide film, 3, a metallic film, and 4, an oxide
film (B) having low internal stress.
As a substrate 1 in this invention, a film or a plate substrate
made of plastic or the like can be used as well as a glass
plate.
The oxide film (B) can be used, so long as the internal stress is
equal to or less than 1.1.times.10.sup.10 dyne/cm.sup.2, and is not
particularly restricted. The internal stress of the film depends
considerably on the deposition condition of the film. The
deposition condition is necessary to be controlled precisely, when
a film of low internal stress, is formed. As a method in which a
tendency of decreasing internal stress of the film is shown, a
method of changing the deposition condition (especially depositing
by a sputtering method), such as, increasing the pressure of the
atmosphere in deposition of the film (sputtering pressure), or
heating the substrate in depositing the film, and a method in which
a heat treatment is performed after depositing the film, are
suggested. By these methods, the internal stress of the film can be
decreased. The respective specific conditions can be chosen
depending upon each apparatus for depositing the film, and are not
particularly restricted.
No particular restriction is made on the material of the film of
the oxide film (B). The film may be of a single layer, or of a
multi-layer. For instance, in case of the laminated glass, there is
a case in which an oxide film, such as chromium oxide, having a
thickness being equal to or less than 100 .ANG., is formed as the
outermost layer in contact with a plastic intermediate film for
lamination with another substrate, for the purpose of controlling
the adhesive strength with the plastic intermediate film, or for
increasing the durability. The film may be composed of at least two
layers including such layer.
No restriction is especially required for a specific film which
comprises the oxide film (B). For instance, a film whose major
component is ZnO, a film whose major component is SnO.sub.2, a film
whose major component is TiO.sub.2, and a multi-layer film which
contains at least two of the above layers, can be used. When other
elements whose ionic radii are smaller than those of Zn.sup.2+ in
oxidized states are added to these films, there is a tendency of
decreasing the internal stress of the film, although there may be a
considerable variation depending on the condition of film
deposition.
Especially, concerning ZnO film comprised in the oxide film (B), as
mentioned above, the internal stress of the zinc oxide film almost
corresponds to the diffraction angle 2.theta. (center of gravity
position) in X-ray diffraction method. The crystal structure of a
film whose major component is zinc oxide is hexagonal. To enhance
the durability of the Low-E film of this invention, the range of
the diffraction angle 2.theta. (center of gravity position) of
(002) diffraction line of the hexagonal zinc oxide in X-ray
diffraction method using CuK.alpha. radiation of the Low-E film, is
desirable to be from 33.88.degree. to 35.00.degree., particularly,
from 34.00.degree. to 34.88.degree.. The value of the diffraction
angle 2.theta. of 34.44.degree. at most, corresponds with the
compressive stress, and the value of 34.44.degree. at least, with
the tensile stress.
When other elements whose ionic radii are smaller than those of
Zn.sup.2+ in oxidized states are added (doped) in the ZnO film,
there is a tendency of decreasing the internal stress, although
depending on the condition of film deposition. A film whose major
component is ZnO, doped with at least one metal selected from the
group consisting of Al, Si, B, Ti, Sn, Mg, and Cr can be used in
the same way as a ZnO film. Since the effect of decreasing the
internal stress remains almost unchanged, when at least one of Al,
Si, B, Ti, Sn, Mg, and Cr, are added in an amount of more than 10%
atomic ratio, of the total amount including Zn, it is sufficient to
add these elements by most at 10% . Concerning the ZnO film doped
with the other elements, the same reasoning is applicable as in ZnO
film, with respect to the deviation of diffraction angle 2.theta.
(center of gravity position) of (002) diffraction line of hexagonal
zinc oxide.
The film thickness of the oxide film (B), although not especially
restricted, is desirable to be within the range of 200 to 700
.ANG., considering a color tone on the total of the Low-E film, and
a visible light transmittance thereof.
When the oxide film (B) is deposited by reactive sputtering in an
oxygen-containing atmosphere, it is preferable to first deposit a
thin metal layer in a non-oxidation atmosphere on the metallic film
(A), in order to prevent the oxidation of the metallic film (A).
The thin metal layer is oxidized to be an oxide layer during the
deposition of the oxide film (B). Therefore the above preferable
thickness of the oxide film (B) includes the thickness of the oxide
layer formed by the oxidation of said thin metal layer.
As an oxide film (B), a multi-layer film can be used, having a
composition of at least two layers by combining films of high
internal stress and those of low internal stress. As a film of low
internal stress, although depending on the condition of the film
deposition, SnO.sub.2 film is suggested because a SnO.sub.2 film of
comparatively low internal stress of 7.0.times.10.sup.9
dyne/cm.sup.2 at most, is relatively easy to deposit. As specific
examples, three layer series such as ZnO/SnO.sub.2 /ZnO, or
SnO.sub.2 /ZnO/SnO.sub.2, or five layer series such as
ZnO/SnO.sub.2 /ZnO/SnO.sub.2 /ZnO, or SnO.sub.2 /ZnO/SnO.sub.2
/ZnO/SnO.sub.2, are suggested in which ZnO films and SnO.sub.2
films are alternatively coated. The internal stress of the total of
the oxide film (B) having these multi-layer films, may be
1.1.times.10.sup.10 dyne/cm.sup.2 at most, and the diffraction
angle of ZnO (002) of the X-ray diffraction is not necessary to be
the above value. Of course it is desirable that the ZnO film has
low internal stress, and diffraction angle of ZnO (002) in X-ray
diffraction method is within the above range.
In case of a multi-layer film which is composed of at least two
layers by combining films of high internal stress and those of low
internal stress, as an oxide film (B), as shown in the above, the
number of layers and the film thickness of a layer, may be chosen
depending on an apparatus, and is not especially restricted, so
long as the total thickness is within the range of 200 to 700
.ANG.. Moreover, the film thickness of each layer may be
different.
Table 2 shows the relationship among the internal stress of the
oxide film (B), the diffraction angle 2.theta. (center of gravity
position) of (002) diffraction line of zinc oxide of a Low-E film
in which the oxide film (B) is formed on Ag/ZnO/glass by a
sputtering method, and the moisture resistance of the Low-E
film.
TABLE 2 Oxide film (B)/Ag/ZnO/glass 450 .ANG. 100 .ANG. 450 .ANG.
Oxide film (B) (002) 450 .ANG. Diffraction A value of line of ZnO
internal stress Diffraction Moisture Material (dyne/cm.sup.2) angle
2.theta. (deg.) resistance 1 ZnO 1.5 .times. 10.sup.10 33.78 X 2
ZnO 1.0 .times. 10.sup.10 33.89 .DELTA. 3 ZnO 6.3 .times. 10.sup.9
34.10 .largecircle. 4 ZnO 1.0 .times. 10.sup.9 34.42 .largecircle.
5 Al-doped ZnO 6.2 .times. 10.sup.9 34.10 .largecircle. 6 B-doped
ZnO 9.5 .times. 10.sup.9 33.89 .largecircle. 7 Si-doped ZnO 7.8
.times. 10.sup.9 33.99 .largecircle. 8 Ti-doped ZnO 4.6 .times.
10.sup.9 34.21 .largecircle. 9 Cr-doped ZnO 6.1 .times. 10.sup.9
34.12 .largecircle. 10 Mg-doped ZnO 7.9 .times. 10.sup.9 33.99
.largecircle. 11 Sn-doped ZnO 5.7 .times. 10.sup.9 34.18
.largecircle. 12 ZnO/SnO.sub.2 /ZnO/ 9.2 .times. 10.sup.9 --
.largecircle. SnO.sub.2 /ZnO
The internal stress in Table 2 is in compressive stress. The
moisture resistance is evaluated by performing a test in which
samples are left in an atmosphere of relative humidity of 95% at
50.degree. C., for 6 days. In this evaluation standard,
.largecircle. is for a sample having no white turbidity at adjacent
to the edge of the film, and no white spot with a diameter of at
least 1 mm, .DELTA. for a sample having no turbidity at adjacent to
the edge of the film, and white spot with a diameter of 1 to 2 mm,
and x for a sample having white turbidity at adjacent to the edge
of the film, and white spot with a diameter at least 2 mm. The
doping quantities of Al, Si, B, Ti, Sn, Mg, and Cr for all the
samples are 4% in atomic ratio, of the total amount including Zn.
In sample 2, the pressure of the atmosphere in film deposition, is
increased compared with sample 1. In sample 3, the temperature of
the substrate in film forming is elevated compared with sample 1.
Sample 4 is heated after film deposition. It is found from Table 2,
that the moisture resistance of the Low-E film, does not depend on
the material of the film, or number of layers; a single layer or
multi-layer, and depends on the internal stress and the diffraction
angle 2.theta. (center of gravity position) of (002) diffraction
line of ZnO.
The oxide film (B) according to the third aspect of the invention
is as follows. By using a multi-layer film as the oxide film (B)
composed of, at least one layer of film whose major component is
zinc oxide, and one layer of film whose major component is tin
oxide, a Low-E film excellent in acid resistance is realized. The
tin oxide is excellent in acid resistance, and the optical property
such as refractive index is almost the same with that of zinc
oxide. Therefore, by replacing a portion of the zinc oxide film,
with tin oxide, an oxide film (B) excellent in acid resistance can
be composed, while maintaining the optical property. On the other
hand, when these films are deposited by a sputtering method,
especially by a direct current sputtering method, a zinc oxide film
can be deposited at a higher rate than tin oxide. Therefore, the
film composition and film thickness of the oxide film (B) must be
determined by considering the desired acid resistance and the film
forming rate.
The film thickness of the oxide film (B), although not especially
restricted, is desirable to be in the range of 200 to 700 .ANG.,
considering the color tone of the total of the Low-E film, and the
visible light transmittance thereof. The number of layers and the
film thickness of a single layer may be chosen according to an
apparatus used, and are not especially restricted. Furthermore, the
thickness of each layer may be different.
Zinc oxide can resist the influence of acid from the edge of the
film, when the zinc oxide layer is divided to a plurality zinc
oxide films, and the film thickness of the single layer of zinc
oxide is made thinner. Accordingly, a specific film composition of
oxide film (B), is specifically composed of a three layer series
such as ZnO/SnO.sub.2 /ZnO, a SnO.sub.2 /ZnO/SnO.sub.2, or five
layer series such as ZnO/SnO.sub.2 /ZnO/SnO.sub.2 /ZnO, or
SnO.sub.2 /ZnO/SnO.sub.2 /ZnO/SnO.sub.2, and the film thickness of
a single layer of zinc oxide is preferably at most 200 .ANG., most
preferably 180 .ANG.. More preferably, the film thickness is
particularly desirable to be at most 100 .ANG. at most, and the
film is composed by the five layer series. Considering the
productivity of film depositing, a multi-layer composed of the five
layer series is preferred, in which the film thickness of the each
layer is about 90 .ANG., and total thickness of the film is about
450 .ANG..
Such oxide film layer (B) is further preferred, when the internal
stress is at most 1.1.times.10.sup.10 dyne/cm.sup.2. When the
internal stress of zinc oxide is low, the film is difficult to be
peeled off by the influence of acid from the edge of the film.
Therefore, the low internal stress of zinc oxide is preferred also
in view of the acid resistance and the moisture resistance. It is
more preferable when the diffraction angle 2.theta. (center of
gravity position) of (002) diffraction line of zinc oxide by X-ray
diffraction method, is within the range of 33.88.degree. to
35.00.degree., particularly, from 34.00.degree. to
34.88.degree..
The material of the oxide film 2 other than oxide film (B) is not
especially restricted. As the oxide film 2, a film of ZnO,
SnO.sub.2, TiO.sub.2, and a multi-layer film containing at least 2
kinds of these, and a film further added with the other elements,
can be utilized. Furthermore, considering the productivity, a film
in which at least two layers of ZnO, SnO.sub.2, and ZnO-SnO.sub.2
are alternatively laminated, and a film in which at least one of
Al, Si, B, Ti, Sn, Mg, and Cr, is added in an amount of at most 10
atomic % of the total quantity including Zn, are preferred.
Considering the color tone and the visible light transmittance
thereof, the thickness of the oxide film 2 is desirable to be in
the range of 200 to 700 .ANG.. In case of a multi-layer film, the
total thickness may be in the range of 200 to 700 .ANG., and the
film thickness of each layer is not restricted.
As the metallic film 3 in the present invention, a metal layer with
high heat reflective function, whose major component is Ag, or Ag
added with at least one of Au, Cu, and Pd, can be utilized. The
metallic film 3 may also be comprised of a metal layer with various
other function, other than the heat reflective metal layer (i.e. Ag
layer), for example, a metal layer, such as Zn, Al, Cr, W, Ni, Ti,
or alloy of these, for controlling the adhesive strength between
the heat reflective metal layer and the oxide film 2 and/or the
oxide film (B), or a metal layer, such as Zn, Al, Cr, W, Ni, Ti, or
alloy of these, with a barrier function for preventing the
diffusion of the metal from the heat reflective metal layer.
Considering the balance between high heat reflective function and
high visible light transmittance, the film thickness of the
metallic film 3 is desirable to be in the range of 50 to 150 .ANG.,
especially about 100 .ANG..
Especially in case of a Low-E film of five layers such as an oxide
film, a metallic film, an oxide film, a metallic film, an oxide
film alternately formed, or a Low-E film of more than five layers,
it is desirable to use an oxide film having an internal stress of
at most 1.1.times.10.sup.10 dyne/cm.sup.2, as an oxide film 2 (an
oxide film other than the oxide film (B).)
Compared with a conventional Low-E film, the moisture resistance of
the Low-E film of the present invention is considerably improved in
moisture resistance, by using a film of at most low internal stress
of 1.1.times.10.sup.10 dyne/cm.sup.2, as an oxide film (B). This is
due to the fact that the oxide film is difficult to be destroyed by
the low internal stress of the oxide film, and the deterioration by
moisture is prevented. Furthermore, the acid resistance is
improved, by introducing a film whose major component is tin oxide
in the oxide layer (B).
EXAMPLES
EXAMPLE 1
An Al doped ZnO film with a thickness of 450 .ANG., is deposited on
a glass substrate, by a direct current sputtering method, in an
atmosphere of Argon and oxygen, of Ar:O.sub.2 =2:8, with pressure
of 6.5.times.10.sup.-3 Torr, using a target made of metal of Al and
Zn, the composition of Al being 3.0 atomic % of the total quantity
including Zn. Next, an Ag film with a thickness of 100 .ANG. is
deposited in an atmosphere of only Ar with pressure of
6.5.times.10.sup.-3 Torr, using Ag as a target. Next, an Al doped
Zn film having a very thin thickness of about 20 .ANG., is
deposited, without changing the atmosphere, using a target made of
a metal of Al and Zn, the Al composition being 3.0 atomic % of the
total quantity including Zn. Lastly, an Al doped ZnO film is
deposited in an atmosphere of Argon and oxygen of Ar:O.sub.2 =2:8,
with a pressure of 6.5.times.10.sup.-3 Torr, using a target made of
metal of Al and Zn, the composition of the Al being 3.0 atomic % of
the total quantity including Zn. During the deposition of the Al
doped ZnO film, the Al doped Zn film is oxidized in the oxygen
containing atmosphere to be Al doped ZnO film. Therefore the total
thickness of Al doped ZnO film deposited on the Ag film is 450
.ANG.. The substrate temperature in depositing film is room
temperature. The dc power density in depositing Al doped ZnO film,
is 2.7 W/cm.sup.2, and 0.7 W/cm.sup.2, in depositing Ag film.
When the obtained Low-E film is checked by X-ray diffraction
method, the diffraction angle 2.theta. (center of gravity position)
of (002) diffraction line of ZnO, is found to be 34.12.degree.. The
internal stress of the Al doped ZnO film (450 .ANG.) formed under
the same condition, is 6.5.times.10.sup.9 dyne/cm.sup.2.
The moisture resistance test is performed on the Low-E film, in
which samples are left in an atmosphere of relative humidity 95% at
50.degree. C., for 6 days. The appearance of the samples after the
moisture resistance test, is favorable, in which although very
small spots are observed, conspicuous white dots and white
turbidity are not observed. According to a SEM photograph of the
surface of the film after the moisture resistance test, almost no
cracks, nor wrinkles, nor exfoliations are observed on the surface
of the film.
A glass on which the above Low-E film is deposited, is laminated
with another glass plate with a plastic intermediate film
therebetween, disposing the Low-E film the adhesive strength being
controlled inside. The same moisture test is carried out also for
the laminated glass. As the result, no white turbidity nor white
spot is observed on the film even after 14 days of the moisture
resistance test.
EXAMPLE 2
A low-E film is deposited, using an RF sputtering method, by
successively coating ZnO film, Ag film, and Al doped ZnO film,
having the film thickness of 450 .ANG., 100 .ANG., and 450 .ANG.,
respectively, on a glass substrate. As a target material, ZnO, Ag,
and ZnO having added Al.sub.2 O.sub.3 (98 weight % ZnO, 2 weight %
Al.sub.2 O.sub.3), respectively, is used and a sputtering is
performed in argon gas. The sputtering pressure is
1.8.times.10.sup.-3 Torr, the substrate temperature is room
temperature, and the RF power density is 3 W/cm.sup.2.
When the obtained Low-E film is checked by X-ray diffraction
method, the diffraction angle 2.theta. (center of gravity position)
of (002) diffraction line of ZnO, is found to be 34.00.degree.. The
internal stress of Al doped ZnO film deposited under the same
condition, is 6.2.times.10.sup.9 dyne/cm.sup.2.
The same moisture resistance test as in Example 1 is carried out on
the above film. The moisture resistance of the film is fair, in
which although very small spots are observed on the film after the
test, no conspicuous white turbidity nor white spot is
observed.
EXAMPLE 3
A Low-E film is produced, which has a film composition of
ZnO/SnO.sub.2 /ZnO/SnO.sub.2 /ZnO/Ag/ZnO/glass, by the same method
as in Example 2. The film thickness of Ag is 100 .ANG., that of ZnO
between Ag and glass, 450 .ANG., and those of ZnO layer and
SnO.sub.2 layer on top of Ag layer, 90 .ANG.. ZnO layer and Ag
layer are obtained by sputtering ZnO and Ag targets in Ar gas, and
SnO.sub.2 layer is obtained by sputtering SnO.sub.2 target in an
atmosphere of a mixed gas of Ar and O.sub.2. The sputtering
pressure, the substrate temperature, and the RF power in film
deposition of ZnO and Ag are the same in the above Example 2. The
power density is 1 W/cm.sup.2 in film deposition of SnO.sub.2, gas
flow rate ratio of Al:O.sub.2 is 8:2.
The internal stress of film of ZnO/SnO.sub.2 /ZnO/SnO.sub.2 /ZnO,
formed under the same condition as above, is 9.2.times.10.sup.9
dyne/cm.sup.2.
The moisture resistance of the Low-E film obtained, is as favorable
as in the above Example.
EXAMPLE 4
A Low-E film is produced, of which film composition is
ZnO/SnO.sub.2 /ZnO/SnO.sub.2 /ZnO/Ag/ZnO/SnO.sub.2 /ZnO/SnO.sub.2
/ZnO/glass, by the same method as in Example 3. The thickness of Ag
layer is 100 .ANG., those of ZnO layer and SnO.sub.2 layer are 90
.ANG. for each layer. The target, and the sputtering gas, the
sputtering pressure, the substrate temperature, and RF power
density, are the same as in Example 3.
The internal stress of the film of ZnO/SnO2/ZnO/SnO2/ZnO produced
under this condition, is 9.2.times.10.sup.9 dyne/cm.sup.2.
The moisture resistance of the obtained Low-E film, is as favorable
as in the above Example.
EXAMPLE 5
A ZnO film, an Ag film and ZnO film, having a film thicknesses of
450 .ANG., 100 .ANG., and 450 .ANG., respectively, are successively
formed on a glass substrate, by the same method as in Example 2. As
target materials, ZnO and Ag are used, and sputterings are
performed in an argon gas atmosphere. The sputtering pressure, the
substrate temperature, the power density are the same as in Example
2. A heat treatment is performed on the film after the film
deposition, in which samples are heated at 400.degree. C. in
N.sub.2 atmosphere, for 1 hour.
When the Low-E film after the heat treatment, is checked by X-ray
diffraction method, the diffraction angle 2.theta. (center of
gravity position) of (002) diffraction line of ZnO, is found to be
34.42.degree..
The moisture resistance of the Low-E film is as favorable as in the
above Example.
COMPARATIVE EXAMPLE 1
A ZnO film, an Ag film, a ZnO film, with film thicknesses of 450
.ANG., 100 .ANG., and 450 .ANG., respectively, are successively
coated on a glass substrate, by the same method as in the above
Example 2. As for target materials, ZnO and Ag are used, and
sputtering is performed in argon gas atmosphere. The sputtering
pressure, the substrate temperature, and the RF power density are
the same as in Example 2.
When the obtained Low-E film is checked by X-ray diffraction
method, the diffraction angle 2.theta. (center of gravity position)
of (002) diffraction line of ZnO is found to be 33.78.degree.. The
internal stress of ZnO film formed under this condition, is
1.5.times.10.sup.10 dyne/cm.sup.2.
The Low-E film after the moisture resistance test, have a thin
turbidity on the whole area of the surface of samples, and
recognizable white spots with diameter of at least 1 mm are clearly
observed.
According to the same SEM photograph after the moisture resistance
test, cracks prevail on the whole area of the surface of the film,
which shows considerable destruction of the film.
A glass on which the above Low-E film is deposited, is laminated
with another glass plate with a plastic intermediate film
therebetween, disposing the Low-E film inside. The same moisture
test is carried out also for this laminated glass. As a result,
clear white turbidity is observed on the edge of the film after 14
days of the moisture resistance test.
EXAMPLE 6
A Low-E film having the composition of ZnO/SnO.sub.2 /ZnO/SnO.sub.2
/ZnO/Ag/ZnO/SnO.sub.2 /ZnO/SnO.sub.2 /ZnO/glass, is made by using
metal targets made of zinc, tin, and silver, respectively, in which
the Ag film is made by a direct current sputtering method, in argon
atmosphere, and the SnO.sub.2 film and the ZnO film are made by a
reactive direct current sputtering method in an atmosphere
containing oxygen. The thickness of Ag film is 100 .ANG. and those
of ZnO film and SnO.sub.2 film are 90 .ANG. for each layer,
respectively. The visible light transmittance of the glass having
such Low-E film is 86%, and its emissivity is 0.06.
An acid resistance test was performed on the glass with Low-E film,
in which the glass is immersed in 1N hydrochloric acid. No change
is observed until 2 minutes after the immersion. However, after 3
minutes the color of the sample begins to change into brownish
color from edge of the film. After 5 minutes a part of the film is
observed to be exfoliated.
COMPARATIVE EXAMPLE 2
A Low-E film having the film composition of ZnO/Ag/ZnO/glass is
made, by using metal targets made of zinc and silver, respectively,
in which the Ag film is made by a direct current sputtering method,
in argon atmosphere, and the ZnO film is made by a reactive direct
current sputtering method, in a atmosphere containing oxygen. The
thickness of the Ag film is 100 .ANG., and the thickness of the ZnO
film is 450 .ANG.. The visible light transmittance of the glass
having the Low-E film, is 86%, and its emissivity is 0.06.
An acid resistance test was performed on the glass with Low-E film,
in which the glass is immersed in 1N hydrochloric acid. The film
begins to be exfoliated just after the immersion, and after 5
minutes, the Low-E film is totally exfoliated from the glass, and
vanished.
In the Low-E film of this invention, the moisture resistance and
the acid resistance are significantly improved. Accordingly, the
handling of the glass with such Low-E film on single plate, is
likely to become easy. Furthermore, the possibility of the
preservation of such glass in single plate for a long time in a
room, is realized. Furthermore the reliability of the Low-E glass
for an automobile or for a building, is promoted. When the film is
used in a laminated glass, the glass is not deteriorated by the
moisture contained in an intermediate film, which improves the
durability of the laminated glass for an automobile or for a
building.
The Low-E film of this invention is electrically conductive, for it
is comprising the metal layer. Therefore the Low-E film of the
present invention can be used in various technical fields, for
example, as an electrode in electronics field (for example, solar
cell), or as a heating element for electrically heated window, or
as an electromagnetic shielding film for a window or for
electronics use. In some cases, the Low-E film of the present
invention can be applied on a substrate with various functioning
layers therebetween, in which case the optical property of this
Low-E film can be adjusted depending on each purpose by choosing
suitable film thickness for each layer comprised in the Low-E film
of the present invention.
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