JP2014124815A - Low-radiation film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, by targeting a low-radiation film possessing three metal layers, a low-radiation film having a favorable appearance in terms of a color tone, above all unaccompanied by a reddish tint when viewed obliquely.SOLUTION: The provided low-radiation film is a low-radiation film formed atop a transparent substrate wherein the low-radiation film possesses a laminate obtained by laminating, in proper order atop the transparent substrate as dielectric layers and metal layers including Ag as a main component, a first dielectric layer, a first metal layer, a second dielectric layer, a second metal layer, a third dielectric layer, a third metal layer, and a fourth dielectric layer, wherein physical film thickness of the respective layers of the laminate are as follows: first dielectric layer: 30-50 nm; first metal layer: 7-19 nm; second dielectric layer: 65-90 nm; second metal layer: 8-20 nm; third dielectric layer: 65-90 nm; third metal layer: 9-20 nm; and fourth dielectric layer: 25-45 nm, wherein the total thickness of the respective dielectric layers of the laminate is 210-240 nm, and wherein the film thickness ratio of the second dielectric layer with respect to the third dielectric layer is confined to a range of 0.95-1.20.

Description

  The present invention relates to a low-emission film used for architectural double glazing, laminated glass, and the like, and particularly provides a window glass that has both high visible light transmittance and solar shading, and has a good appearance color tone. It relates to a low-emission film suitable for the above.

  Multi-layer glass that prevents indoor heating heat from flowing outside in winter is widely used as window glass for houses and buildings. The multi-layer glass has a structure in which at least two plate glasses are bonded via a spacer, and the hollow layer between the two glasses is made of dry air or a gas having low thermal conductivity such as Ar or Kr. It is an encapsulated product.

  Low Emissivity (hereinafter referred to as Low-E) multi-layer glass, which has been provided with summer solar radiation shielding in addition to the above-described winter heat insulation, has been rapidly spread as a window glass useful for energy saving throughout the year. Low-E double glazing is provided with a low radiation film on the surface of the glass in contact with the hollow layer between the two glasses. The low emission film has a laminated structure in which a dielectric layer such as a metal oxide and a metal layer such as Ag are laminated. Low-E double-glazed glass as described above has the property of reflecting solar heat flowing from the outside into the room due to the solar radiation shielding performance of the low-radiation film. be able to.

  Low emission films used for the Low-E multilayer glass and the like are well known, and a laminated structure in which 2n + 1 layers of dielectric layers and Ag layers are laminated is disclosed (Patent Document 1).

  Moreover, the low radiation film | membrane provided with three Ag layers is disclosed as a low radiation film | membrane formed into a film on the window glass surface of a building, and has a favorable color tone and the outstanding visible light transmittance (patent document 2). . In the low radiation film having three Ag layers, the total thickness of the Ag layer is at least 425 mm (= 42.5 nm, 47.2 to 47. 7 nm).

  Further, it is disclosed that a low radiation film using an oxide, nitride, or the like as a dielectric layer is less likely to be reddish or yellowish with respect to incident light from vertical and oblique directions (Patent Document 3). Many studies have been made on the above-described appearance problems in a low-emission film having one or two metal layers, and it is disclosed that each layer is set to an optimum film thickness range as a solution (patent). Document 4 and Patent document 5).

Japanese Patent Laid-Open No. 63-239044 JP 2007-106668 A Japanese Patent Application Laid-Open No. 11-124689 JP-A-11-34216 JP 2010-195638 A

  In recent years, demands for energy saving and power saving have increased, and it has been required that architectural windows have both solar shading and daylighting. In the low emission film as described above, by increasing the number of metal layers to three or more, a low visible light reflectance can be realized using the optical interference effect, and thus excellent daylighting properties are easily obtained. At the same time, the total film thickness of the metal layer can be increased as compared with the low radiation film having one or two conventional metal layers, so that it can also have higher solar radiation shielding than the conventional one.

  On the other hand, the higher the heat shielding property of the low-reflection film, that is, the reflectance in the near infrared region, the more the reflectance near 700 nm, which is the boundary region between the visible region and the near infrared region, is affected. The color tone becomes reddish, and the reflected color tone in an oblique direction is particularly reddish. When the low-emission film is used for a window of a building or a house, it is preferable to avoid a reddish reflection color tone because a gentle appearance color tone is preferred in these applications.

  Further, as the number of layers of the low radiation film is increased, the relationship between the thickness of the metal layer and the dielectric layer and the solar radiation shielding property or color tone becomes more complicated, and the knowledge about the low radiation film having one or two metal layers Since the above-mentioned redness cannot be solved alone, a new optimal low-emission film configuration is required.

  Thus, an object of the present invention is to provide a low-emission film that has a good appearance color tone, particularly, no redness when viewed from an oblique direction, in a low-emission film having three metal layers.

The present invention is a low emission film formed on a transparent substrate, and the low emission film includes a dielectric layer and a metal layer mainly composed of Ag, the first dielectric layer on the transparent substrate. , A first metal layer, a second dielectric layer, a second metal layer, a third dielectric layer, a third metal layer, and a fourth dielectric layer are laminated in this order, The physical film thickness of each layer is
The first dielectric layer is 30-50 nm,
The first metal layer is 7 to 19 nm,
The second dielectric layer is 65-90 nm,
The second metal layer is 8-20 nm,
A third dielectric layer of 65-90 nm,
The third metal layer is 9-20 nm,
The fourth dielectric layer is 25-45 nm;
The total thickness of the dielectric layers of the laminate is 210-240 nm;
The ratio of the film thickness of the second dielectric layer to the third dielectric layer is in the range of 0.95 to 1.20.

  The metal layer containing Ag as a main component is an Ag film or an Ag alloy film containing Ag as a main component. As the Ag alloy, 5% by mass of a metal such as palladium, gold, platinum, nickel, or copper is used. It may be included within the following range. Here, the “main component” indicates that containing 90% by mass or more of Ag.

  In the laminate, the thickness t1 of the first dielectric layer and the thickness t2 of the second dielectric layer are t2> t1, and the thickness t3 of the third dielectric layer and the thickness t4 of the fourth dielectric layer are t3. > T4. When the thickness of each dielectric layer does not satisfy the above inequality, it is not possible to obtain a preferable appearance color tone such as a low emission film having a red reflection color tone or a high visible light reflectance.

  The dielectric layer is a layer for adjusting the reflection color tone of the low radiation film, and is an oxide, nitride, or at least one metal selected from the group consisting of Zn, Sn, Al, Ti, Si, and In, or A transparent thin film of oxynitride is preferably used.

  The physical film thickness of the dielectric layer and the metal layer is obtained by dividing the film formation speed of each layer estimated by the following procedure by the substrate conveyance speed set when forming the low radiation film. Is possible. The film formation speed (nm · mm / min) of each layer of the dielectric layer or metal layer is the thickness of the single layer film (nm) and the substrate transport speed (mm) when the single layer film of each layer is formed. / Min). The thickness of the single layer film is determined by marking the glass substrate with a marker such as an oil pen before film formation and removing the film after film formation. The level difference from the portion where it was not formed was measured using a stylus type level meter (Veeco, Dektak 150).

  By making each layer of the laminate within the above-mentioned range, it is possible to make the solar radiation transmittance measured in accordance with JIS R3106 0.40% or less and the visible light transmittance 60% or more. Can be prevented from exhibiting redness. In the present invention, each optical characteristic of the low emission film was measured using a self-recording spectrophotometer (manufactured by Hitachi, Ltd., U-4000).

  Further, in the examples described below, the reddish glaring and interference fringes when viewed from near 45 degrees obliquely with respect to the transparent base material surface are described as “reddish”. The angle is not limited.

  The low emission film of the present invention is a low emission film having three metal layers, and provides a low emission film that does not exhibit redness when viewed from an oblique angle with respect to a transparent base material surface, particularly with respect to a transparent substrate surface. Is possible.

It is a cross-sectional schematic diagram showing the low radiation film | membrane of this invention. It is a figure which shows the outline of a magnetron sputtering device.

An outline of the low emission film of the present invention is shown in FIG. The low radiation film of the present invention is a low radiation film formed on the transparent substrate 1, and the low radiation is produced by the dielectric layer 2 and the metal layer 3 containing Ag as a main component from the transparent to the first dielectric. A body layer, a first metal layer, a second dielectric layer, a second metal layer, a third dielectric layer, a third metal layer, and a fourth dielectric layer are stacked in this order.
The physical film thickness of each layer in the laminate is 30 to 50 nm for the first dielectric layer, 7 to 19 nm for the first metal layer, 65 to 90 nm for the second dielectric layer, 8 to 20 nm for the second metal layer, The third dielectric layer is 65-90 nm, the third metal layer is 9-20 nm, the fourth dielectric layer is 25-45 nm, the total thickness of the dielectric layers of the laminate is 210-240 nm, The ratio of the film thickness of the second dielectric layer to the body layer is in the range of 0.95 to 1.20.
When the total thickness of the dielectric layers of the laminate is out of the above range, or the ratio of the thickness of the second dielectric layer to the third dielectric layer is out of the above range, the transparent substrate surface is viewed obliquely from 45 degrees. In this case, the reflected color is red as a stimulating color, and a preferable appearance color tone cannot be obtained.

  The low radiation film may have a coating or a dielectric layer on the laminate. Moreover, it is preferable that the total thickness of a metal layer is 30-47 nm by a physical film thickness. If it is less than 30 nm, it is not possible to obtain preferable solar shading performance, and if it exceeds 47 nm, the visible light reflectance increases and the visible light transmittance decreases, so that preferable daylighting properties cannot be obtained.

  The dielectric layer is preferably a transparent thin film of oxide, nitride, or oxynitride containing at least one metal selected from the group consisting of Zn, Sn, Al, Ti, Si, and In, as described above. Used for.

As the dielectric layer, to improve the adhesion between the transparent substrate and the metal layer, to improve the chemical durability of the low emission film, to obtain a preferable appearance color tone using the optical interference effect, etc. For the purpose, in particular, ZnO or ZnO to which Al is added (hereinafter sometimes referred to as AZO), SnO ₂ , TiO ₂ thin films, multi-layers of these thin films, and mixed films of these oxides are used. preferable.

  The low-emission film preferably has a protective film layer between the metal layer and the dielectric layer subsequently formed thereon. The protective film layer is preferably formed directly on the metal layer. By forming the protective film layer, a dielectric layer such as a metal oxide, a metal nitride, or a metal oxynitride is formed. It is possible to protect the metal layer by preventing the deterioration of the metal layer due to the oxygen or nitrogen plasma generated.

  For the protective film layer, at least one selected from the group consisting of Zn, Sn, Ti, Al, Si, NiCr, Cr, Zn alloy, and Sn alloy, or 0.01 to 0.01% of Al or Sb metal as the metal. A material containing 10.0% by mass or a lower oxide thin film of the metal or the alloy can be used, and is appropriately selected in consideration of adhesion to a metal layer or a dielectric layer. The physical film thickness of the protective film layer is preferably about 1 to 7 nm, more preferably about 2 to 3 nm.

  The dielectric layer, metal layer, and protective layer of the low-emission film are preferably formed by a vapor deposition process such as a sputtering method because of their good productivity. In particular, a magnet is placed behind the sputtering target. It is preferable to form a film by a magnet sputtering method in which a plasma is confined in the vicinity of a target surface by a magnetic field and a film is formed by particles sputtered from the target.

  In the sputtering method, any power source such as a DC power source, an AC power source, and a power source in which AC and DC are superimposed can be suitably used as a plasma generation source, but a power source in which AC and DC are superimposed has excellent continuous productivity. It can be suitably used.

  As the film forming apparatus, a magnetron sputtering apparatus as shown in FIG. 2 is suitable. FIG. 2 shows a main part when the apparatus is observed from above. In this apparatus, a target 5 is bonded on a backing plate 4, a transparent substrate 7 is held on a substrate holder 6, and then the inside of the vacuum chamber 8 is evacuated using a vacuum pump 9, After introducing the atmospheric gas into 8, the power is applied to the target to form a film. The pressure in the vacuum chamber 8 during film formation is preferably adjusted by the open / close valve 11 in the range of 0.1 to 1.0 Pa. Further, the transport speed of the holder 6 that transports the transport roll 13 is adjusted so that a desired film thickness is obtained during film formation.

  Note that the type of vacuum pump, the number and type of targets, selection of a DC power supply and an AC power supply, output power to the target, pressure during film formation, and the like may be appropriately selected and are not particularly limited. Details of FIG. 2 will be described later in the embodiment.

  Although a transparent base material is not specifically limited, For example, there exists inorganic transparency, such as a window glass for buildings, the glass plate glass normally used, or the soda-lime glass manufactured by the roll-out method Flat glass can be used. The plate glass can be used for both colorless glass such as clear glass and high transmission glass, and green colored such as heat ray absorbing glass, and is not particularly limited to the shape of the glass, but visible light. In consideration of the transmittance, it is preferable to use colorless glass such as clear glass and high transmittance glass. In addition to flat glass, bent glass, various glass such as air-cooled tempered glass and chemically tempered glass, netted glass can be used. Furthermore, various glass substrates such as borosilicate glass, low expansion glass, zero expansion glass, low expansion crystallized glass, and zero expansion crystallized glass can be used. Further, examples other than the glass substrate include transparent resin substrates such as polyethylene terephthalate resin, polycarbonate resin, and polyvinyl chloride resin.

  The transparent base material having the low emission film formed on the surface thereof is preferably used for architectural window glass as multilayer glass or laminated glass. When used for architectural glass, a gentle color tone is preferred as described above. Therefore, the glass surface reflection color tone of the low emission film of the present invention is preferably in the range of -10 to 0 and b * in the range of -10 to 5 in the CIE Lab color system.

1. Production of Low Emission Film As shown in FIG. 1, a low emission film in which dielectric layers 2 and metal layers 3 are alternately formed on the surface of a transparent substrate 1 was formed. The laminated structure of the low-emission film is composed of a transparent base material, a first dielectric layer, a first metal layer, a second dielectric layer, a second metal layer, a third dielectric layer, a third metal layer, and a fourth dielectric layer. A protective film layer (not shown) between the first metal layer and the second dielectric layer, a protective film layer (not shown) between the second metal layer and the third dielectric layer, A low radiation film formed by inserting a protective film layer (not shown) between the three metal layers and the fourth dielectric layer was formed. As the transparent substrate, soda lime glass having a thickness of 3 mm was used. Table 1 shows the film thicknesses of the metal layers and the dielectric layers of the examples and comparative examples.

Example 1
A zinc oxide film to which Al is added as a dielectric layer (hereinafter sometimes referred to as an AZO film), an Ag film as a metal layer, and a zinc film to which Al is added as a protective film layer (hereinafter referred to as an AZ film) May be called). Low-emission film formation was performed using the magnetron sputtering apparatus shown in FIG.

  After holding the transparent substrate 1 on the substrate holder 6, the vacuum chamber 8 was evacuated by the vacuum pump 9 to form a first dielectric layer. During film formation, the vacuum pump 9 is continuously operated, and the atmospheric gas in the vacuum chamber is introduced with oxygen gas from the gas introduction pipe 10 and the flow rate of oxygen gas is controlled by a mass flow controller (not shown). It was adjusted. A turbo molecular pump was used as the vacuum pump 9. The pressure in the vacuum chamber during film formation was adjusted to 0.3 Pa by controlling the opening degree of the opening / closing valve 11 installed between the vacuum chamber and the vacuum pump. As the target 5 having the magnet 14 disposed on the back side, a Zn target added with Al (hereinafter referred to as AZ target) is used, and the power supplied from the DC power source 12 to the AZ target through the power cable 15 is 1000 W. did. The base material holder 6 was transported on the transport roll 13, passed by the side of the target 5, and adjusted the transport speed so that the AZO film thickness was 32 nm. In addition, about any film | membrane after that, the desired film thickness was obtained by controlling a conveyance speed, and the heating of the base material was not performed intentionally.

  Next, an Ag film as a first metal layer was continuously formed on the AZO film as the first dielectric layer while maintaining a vacuum. An Ag target was used as the target 5, and the atmospheric gas in the vacuum chamber 8 was introduced with argon gas from the gas introduction pipe 10, and the pressure was adjusted to 0.5 Pa by controlling the open / close valve 11. The power supplied from the DC power source 12 to the Ag target 5 through the power cable 15 was 360 W. The conveyance speed of the base material holder 6 was controlled so that the thickness of the Ag film was 15 nm.

  Next, a protective film layer was continuously formed on the Ag film as the first metal layer while maintaining a vacuum. An AZ target was used as the target 5, and the atmospheric gas in the vacuum chamber 8 was introduced with argon gas from the gas introduction pipe 10, and the pressure was adjusted to 0.7 Pa by controlling the open / close valve 11. The power supplied from the DC power source 12 to the Ag target 5 through the power cable 15 was 120 W. The conveyance speed of the substrate holder 6 was controlled so that the thickness of the AZO film was 2.8 nm.

  Next, a second dielectric layer was continuously formed on the protective film layer while maintaining a vacuum. The conveyance speed of the substrate holder 6 was controlled so that the thickness of the AZO film was 83 nm, and other film formation conditions were set in the same manner as the film formation conditions for the first dielectric layer.

  Next, an Ag film as a second metal layer was continuously formed on the AZO film as the second dielectric layer while maintaining a vacuum. The conveyance speed of the substrate holder 6 was controlled so that the thickness of the Ag film was 13 nm, and other film formation conditions were set in the same manner as the film formation conditions for the first metal layer.

  Next, a protective film layer was continuously formed on the Ag film as the second metal layer while maintaining a vacuum. The film formation conditions were set in the same manner as the film formation conditions for the protective film layer formed between the first dielectric layer and the first metal layer.

  Next, a third dielectric layer was continuously formed on the protective film layer while maintaining a vacuum. The transport speed of the substrate holder 6 was controlled so that the thickness of the AZO film was 71 nm, and other film formation conditions were set in the same manner as the film formation conditions for the first dielectric layer.

  Next, an Ag film as a third metal layer was continuously formed on the AZO film as the third dielectric layer while maintaining a vacuum. The conveyance speed of the substrate holder 6 was controlled so that the thickness of the Ag film was 14 nm, and other film formation conditions were set in the same manner as the film formation conditions for the first metal layer.

  Next, a protective film layer was continuously formed on the Ag film as the third metal layer while maintaining a vacuum. The film formation conditions were set in the same manner as the film formation conditions for the protective film layer formed between the first dielectric layer and the first metal layer.

  Next, a fourth dielectric layer was continuously formed on the protective film layer while maintaining a vacuum. The transport speed of the substrate holder 6 was controlled so that the thickness of the AZO film was 34 nm, and other film formation conditions were set in the same manner as the film formation conditions for the first dielectric layer.

Example 2
The thickness of the AZO film as the first dielectric layer is 32 nm, the thickness of the Ag film as the first metal layer is 15 nm, the thickness of the AZO film as the second dielectric layer is 83 nm, and the second metal layer. The thickness of the Ag film is 13 nm, the thickness of the AZO film as the third dielectric layer is 73 nm, the thickness of the Ag film as the third metal layer is 14 nm, and the thickness of the AZO film as the fourth dielectric layer is The film thickness was set to 36 nm, and other film forming conditions were set in the same manner as in Example 1 to form a low radiation film.

Example 3
The thickness of the AZO film as the first dielectric layer is 36 nm, the thickness of the Ag film as the first metal layer is 14 nm, the thickness of the AZO film as the second dielectric layer is 79 nm, and the second metal layer. The thickness of the Ag film is 11 nm, the thickness of the AZO film as the third dielectric layer is 69 nm, the thickness of the Ag film as the third metal layer is 13 nm, and the thickness of the AZO film as the fourth dielectric layer is The thickness was set to 34 nm, and other film forming conditions were set in the same manner as in Example 1 to form a low radiation film.

Example 4
The thickness of the AZO film as the first dielectric layer is 45 nm, the thickness of the Ag film as the first metal layer is 9.2 nm, the thickness of the AZO film as the second dielectric layer is 77 nm, and the second metal layer The thickness of the Ag film that is 12 nm, the thickness of the AZO film that is the third dielectric layer is 80 nm, the thickness of the Ag film that is the third metal layer is 12.5 nm, and the AZO film that is the fourth dielectric layer Was set to 31 nm, and other film formation conditions were set in the same manner as in Example 1 to form a low radiation film.

Example 5
The thickness of the AZO film as the first dielectric layer is 36 nm, the thickness of the Ag film as the first metal layer is 7 nm, the thickness of the AZO film as the second dielectric layer is 74 nm, and the second metal layer. The thickness of the Ag film is 11 nm, the thickness of the AZO film as the third dielectric layer is 73 nm, the thickness of the Ag film as the third metal layer is 9 nm, and the thickness of the AZO film as the fourth dielectric layer is The film thickness was set to 32 nm, and other film forming conditions were set in the same manner as in Example 1 to form a low radiation film.

Example 6
The thickness of the AZO film as the first dielectric layer is 32 nm, the thickness of the Ag film as the first metal layer is 19 nm, the thickness of the AZO film as the second dielectric layer is 83 nm, and the second metal layer. The thickness of the Ag film is 13 nm, the thickness of the AZO film as the third dielectric layer is 73 nm, the thickness of the Ag film as the third metal layer is 14 nm, and the thickness of the AZO film as the fourth dielectric layer is The film thickness was set to 36 nm, and other film forming conditions were set in the same manner as in Example 1 to form a low radiation film.

Comparative Example 1
The thickness of the AZO film as the first dielectric layer is 36 nm, the thickness of the Ag film as the first metal layer is 15 nm, the thickness of the AZO film as the second dielectric layer is 82 nm, and is the second metal layer The thickness of the Ag film is 13 nm, the thickness of the AZO film as the third dielectric layer is 68 nm, the thickness of the Ag film as the third metal layer is 14 nm, and the thickness of the AZO film as the fourth dielectric layer is The film thickness was set to 36 nm, and other film forming conditions were set in the same manner as in Example 1 to form a low radiation film.

Comparative Example 2
The thickness of the AZO film as the first dielectric layer is 39 nm, the thickness of the Ag film as the first metal layer is 7 nm, the thickness of the AZO film as the second dielectric layer is 67 nm, and is the second metal layer The thickness of the Ag film is 11 nm, the thickness of the AZO film as the third dielectric layer is 71 nm, the thickness of the Ag film as the third metal layer is 9 nm, and the thickness of the AZO film as the fourth dielectric layer is The film thickness was set to 27 nm, and other film forming conditions were set in the same manner as in Example 1 to form a low radiation film.

2. Evaluation of Low Radiation Film The optical characteristics of the laminated article were measured using a self-recording spectrophotometer (manufactured by Hitachi, Ltd., U-4000). Visible light transmittance and solar radiation transmittance were calculated according to JIS R3106, and the glass surface reflection color tone was expressed in the CIE Lab color system. Table 2 shows the values of the optical characteristics of the low-emission film in each example and comparative example. Further, the redness of the reflected color was determined as “Yes” when the glass surface was observed from an oblique angle of 45 degrees and reddish glare, interference fringes, etc. were observed.

  The low radiation films of Examples 1 to 6 and Comparative Examples 1 to 2 have a visible light transmittance of 69% or more and a solar radiation transmittance of 39% or less, and are preferable for daylighting and solar radiation shielding properties as an energy saving window glass for buildings. Had. However, the low radiation films of Comparative Examples 1 and 2 have a red color that is a stimulating color when the glass surface is viewed obliquely from 45 degrees, and have a preferable appearance when formed on a window glass surface of a building. I couldn't say anything. On the other hand, Examples 1-6 did not exhibit redness even when viewed obliquely, and had a more gentle appearance color tone.

  From the above, in the embodiment of the present invention, in the low radiation film having three metal layers, by controlling the thickness and thickness ratio of the dielectric layer and the metal layer, in addition to excellent daylighting and solar shading. Thus, it can be said that it is possible to have an appearance color tone preferable as a low radiation film formed on the window glass surface of the building.

DESCRIPTION OF SYMBOLS 1 Transparent base material 2 Dielectric layer 3 Metal layer 4 Backing plate 5 Target 6 Base material holder 7 Plate glass 8 Vacuum chamber 9 Vacuum pump 10 Gas introduction pipe 11 Opening / closing valve 12 DC power supply 13 Transport roll 14 Magnet 15 Power cable

Claims (4)

A low-emission film formed on a transparent substrate, the low-emission film comprising a dielectric layer and a metal layer mainly composed of Ag, the first dielectric layer and the first metal on the transparent substrate And a physical layer of each layer in the multilayer body, the second dielectric layer, the second metal layer, the third dielectric layer, the third metal layer, and the fourth dielectric layer. Thickness is
The first dielectric layer is 30-50 nm,
The first metal layer is 7 to 19 nm,
The second dielectric layer is 65-90 nm,
The second metal layer is 8-20 nm,
A third dielectric layer of 65-90 nm,
The third metal layer is 9-20 nm,
The fourth dielectric layer is 25-45 nm;
The total thickness of the dielectric layers of the laminate is 210-240 nm;
A low radiation film, wherein the ratio of the film thickness of the second dielectric layer to the third dielectric layer is in the range of 0.95 to 1.20. 2. The low emission film according to claim 1, wherein the total thickness of the metal layer is 30 to 47 nm in physical thickness in the laminate. The low radiation film according to claim 1, wherein the laminate includes a protective film layer on the metal layer. The window glass of the building which formed the low radiation film in any one of Claims 1-3 on the surface.

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