EP4048518A1

EP4048518A1 - Transparent substrate with a multilayer thin film coating and a multiple glazing unit comprising the same

Info

Publication number: EP4048518A1
Application number: EP20879757.1A
Authority: EP
Inventors: Kangmin KIM; Jin Woo Han
Original assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Current assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Priority date: 2019-10-25
Filing date: 2020-10-19
Publication date: 2022-08-31
Also published as: BR112022001749A2; WO2021080266A1; KR20210050042A; EP4048518A4; MX2022004929A

Abstract

A transparent substrate with a multilayer thin film coating according to an example embodiment of the present invention includes a transparent substrate and a multilayer thin film coating, wherein the multilayer thin film coating includes a lower anti-reflection film, a lower metal protective layer, a metal functional layer having an infrared reflecting function, an upper metal protective layer, and an upper anti-reflection film sequentially stacked from the transparent substrate, each of the upper anti-reflection film and the lower anti-reflection film includes at least one dielectric layer, the upper anti-reflection film includes a silicon nitride-based dielectric layer, and the silicon nitride-based dielectric layer is stacked in direct contact with the upper metal protective layer and has a thickness of greater than or equal to 30 nm, a sum of the thickness of the lower metal protective layer and the upper metal protective layer is 0.6 nm to 2.25 nm, and a thickness of the lower metal protective layer is greater than that of the upper metal protective layer.

Description

TRANSPARENT SUBSTRATE WITH A MULTILAYER THIN FILM coating AND A MULTIPLE GLAZING UNIT COMPRISING THE SAME

A transparent substrate provided with a multilayer thin film coating and a multiple glazing unit including the same are disclosed. Specifically, a transparent substrate provided with a multilayer thin film coating having improved durability and optical properties by adjusting a configuration of a layer included in the multilayer thin film coating formed on the transparent substrate, and a multiple glazing unit including the same are disclosed.

Low-emissivity glass is glass in which a low-emission layer including a metal having high reflectance in an infrared region such as silver (Ag) is deposited as a thin film. This low-emissivity glass is a functional material that reflects radiant rays in the infrared region so as to block solar radiation flowing from outdoors to indoors in summer and preserve heating room radiant heat flowing out from indoors to outdoors to bring about an energy-saving effect in buildings. Emissivity in glass refers to a degree to which the glass reflects energy of infrared with a long wavelength (2500 nm to 40,000 nm). The lower the emissivity, the better the glass reflects, and thus the more infrared energy it reflects, and accordingly, since less heat is transferred, a heat transmission rate is decreased, and thereby a heat insulation effect is increased. For example, general glass with no coating has emissivity of about 0.84, wherein the existing of the coating will lower the emissivity. For example, glass having a low emissivity coating layer may have emissivity of 0.10. When the emissivity is low, a shield coefficient is also low.

On the other hand, a coating in low-emissivity glass is generally composed of several layers including a dielectric material layer. When such a coating is deposited on a transparent substrate (glass substrate), light reflection is reduced while transmission is increased thus the visibility of objects behind the substrate is improved.

This low-emissivity glass is widely applied to exterior walls of buildings and the like, but in such an environment in which it is exposed to the outside, a low-emissivity layer containing a metal with high reflectivity may be easily corroded and damaged by moisture, oxygen, etc. This damage weakens a bonding force between the glass and the coating or between the layers included in the coating, and as a result, there may be a significant problem that the glass installed on the exterior wall of a building may fall and the like. In order to solve this problem, an effort to add a layer for prevention of the corrosion of the multilayer thin film coating, increasing the thickness, or the like has been made, which may lead to another problem of deteriorating optical properties such as transmittance and the like.

The present invention is to solve these problems by providing a transparent substrate including a multilayer thin film coating which may improve durability and simultaneously maintain excellent properties such as transmittance, emissivity, and the like, and a multiple glazing unit including the same.

However, exemplary embodiments of the present invention are not limited thereto but may be applied in various ways within the scope of the technical idea included therein.

A transparent substrate with a multilayer thin film coating according to an embodiment of the present invention includes a transparent substrate and a multilayer thin film coating, and the multilayer thin film coating includes a lower anti-reflection film, a lower metal protective layer, a metal functional layer having an infrared reflecting function, an upper metal protective layer, and an upper anti-reflection film sequentially stacked from the transparent substrate, wherein each of the upper anti-reflection film and the lower anti-reflection film includes at least one dielectric layer, the upper anti-reflection film includes a silicon nitride-based dielectric layer, and the silicon nitride-based dielectric layer is stacked in direct contact with the upper metal protective layer and has a thickness of greater than or equal to 30 nm, a sum of the thickness of the lower metal protective layer and the upper metal protective layer is 0.6 nm to 2.25 nm, and a thickness of the lower metal protective layer is greater than that of the upper metal protective layer.

An overcoat may be further included on one surface of the upper antireflection film in a direction away from the transparent substrate, and the overcoat may include Zr-doped titanium oxide or zirconium oxide.

The lower metal protective layer may have a thickness of 0.5 nm to 1.3 nm.

The upper metal protective layer may have a thickness of 0.2 nm to 0.6 nm.

The metal functional layer may have a thickness of 12 nm to 18 nm.

Each of the upper metal protective layer and the lower metal protective layer may include at least one of titanium, nickel, chromium, and niobium, or an alloy thereof.

Each of the upper metal protective layer and the lower metal protective layer may include a nickel-chromium alloy.

The lower anti-reflection film may include a silicon nitride.

Each of the lower anti-reflection film and the upper anti-reflection film may further include at least one nitride, oxide, or oxynitride selected from titanium (Ti), hafnium (Hf), zirconium (Zr), and aluminum (Al).

The lower anti-reflection film may include a lower dielectric layer disposed on the transparent substrate and an upper dielectric layer disposed on the lower dielectric layer, and the lower dielectric layer may further include doped zirconium.

The lower anti-reflection film may have a thickness of 30 nm to 45 nm, and the upper anti-reflection film may have a thickness of 35 nm to 50 nm.

A thickness ratio of the upper anti-reflection film to the lower anti-reflection film may be greater than or equal to 1.1 and less than or equal to 1.4.

A thickness ratio of the lower metal protective layer to a total thickness of the lower metal protective layer and the upper metal protective layer (lower/(lower + upper)) may be greater than 0.5 and less than 1.

A ratio of visible light transmittance to normal emissivity (= visible light transmittance/normal emissivity) may be greater than 14.

When dipped in an aqueous solution of 0.1 N of H₂SO₄ and 10 wt% of NaCl at room temperature, a time until which visible corrosion does not occur may be greater than or equal to 168 hours.

The visible light transmittance (TL) may be 70 % to 80 %.

It may be a multilayer thin film coating having coating surface reflectance of less than 10 %.

In CIELAB color coordinates, the coated surface may have a reflective color of 5 ≤ a* ≤ 10 and -20 ≤ b* ≤ -10.

Normal emissivity may be 0.03 to 0.05.

Sheet resistance of the multilayer thin film coating may be less than 4.0 Ω/square.

A multiple glazing unit according to an embodiment of the present invention is a multiple glazing unit including at least two transparent substrates spaced apart from each other with a spacer therebetween, wherein at least one of the at least two transparent substrates is the aforementioned transparent substrate with a multilayer thin film coating.

According to an embodiment of the present invention, even if a multilayer thin film coating having an infrared reflecting function is provided, a coated article in which an enamel coating having improved adhesion and surface quality is applied may be obtained.

FIG. 1 is a view showing a cross-section of a transparent substrate provided with a multilayer thin film coating according to an embodiment of the present invention.

FIG. 2 is a view showing a cross-section of a multiple glazing unit according to an embodiment of the present invention.

FIG. 3 is a photograph showing the state of each of the examples and comparative examples 7 days after the start of the dipping test for a transparent substrate with a multilayer thin film coating.

FIG. 4 is a photograph showing the state of each of the examples and comparative examples 28 days after the start of a high-temperature and high-humidity test for a transparent substrate with a thin film multilayer coating.

FIG. 5 is a photograph showing the states of each of the examples and comparative examples when a certain period elapses after the start of the field test for the multiple glazing units.

FIG. 6 is a photograph showing the states of each of the examples and comparative examples when a certain period elapses after the start of the spray test for the multiple glazing unit.

Terms such as first, second, and third are used to describe various parts, components, regions, layers, and/or sections, but are not limited thereto. These terms are only used to distinguish one part, component, region, layer, or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

The terminology used herein is for referring only to specific embodiments and is not intended to limit the present invention. Singular forms as used herein also include plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising" as used in the specification specifies a particular characteristic, region, integer, step, action, element, and/or component, and presence or addition of another characteristic, region, integer, step, action, element, and/or component is not excluded.

When a part is referred to as being "on" or "on" another part, it may be directly on or on another part, or other parts may be involved in between. In contrast, when a part is referred to as being "directly on" another part, no other part is intervened.

In the present invention, the terms "emissivity" and "transmittance" are used as commonly known in the art. "Emissivity" is a measure of how much light is absorbed and reflected at a given wavelength. In general, the following equation is satisfied.

(Emissivity) = 1 - (Reflectance)

For architectural applications, an emissivity value of about 2500 to 50000 nm in the infrared spectrum is important.

As used herein, the term "transmittance" means visible light transmittance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meanings as those generally understood by those with ordinary knowledge in the field of art to which the present invention belongs. Such terms as those defined in a generally used dictionary are to be interpreted to have the same meanings as contextual meanings in the relevant field of art, and are not to be interpreted to have idealized or excessively formal meanings unless clearly defined in the present application.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

FIG. 1 is a view showing a cross-section of a transparent substrate 100 provided with a multilayer thin film coating according to an embodiment of the present invention. The transparent substrate 100 with a multilayer thin film coating of FIG. 1 is for illustrative purposes only, and the present invention is not limited thereto. Accordingly, the transparent substrate 100 with the multilayer thin film coating of FIG. 1 may be transformed into various forms.

Referring to FIG. 1, a transparent substrate 100 with a multilayer thin film coating according to an embodiment of the present invention includes a transparent substrate 110 and a multilayer thin film coating 120 formed on the transparent substrate 110.

The transparent substrate 110 is not particularly limited, but is desirably made of a hard inorganic material such as glass or an organic material based on a polymer.

The multilayer thin film coating 120 includes a lower anti-reflection film 20, a lower metal protective layer 30, a metal functional layer 40 having an infrared reflecting function, an upper metal protective layer 50, and an upper anti-reflection film 60 which are sequentially stacked from the transparent substrate 110. An overcoat 70 is further included on the top of the upper anti-reflection film 60, that is, on one side in a direction away from the transparent substrate 100.

Each of the lower anti-reflection film 20 and the upper anti-reflection film 60 may respectively include at least one dielectric layer. The dielectric layer may include a metal oxide, a metal nitride, or a metal oxynitride. The metal may include at least one selected from titanium (Ti), hafnium (Hf), zirconium (Zr), zinc (Zn), indium (In), tin (Sn), and silicon (Si).

The lower anti-reflection film 20 and the upper anti-reflection film 60 may respectively be a single layer or a stack of two or more layers. According to an embodiment, as shown in FIG. 1, the lower anti-reflection film 20 may include a lower dielectric layer 21 disposed on the transparent substrate 110 and an upper dielectric layer 22 disposed on the lower dielectric layer 21, that is, on the side away from the transparent substrate 110. The lower dielectric layer 21 and the upper dielectric layer 22 may include silicon nitride (Si₃N₄). Herein, the upper dielectric layer 22 may be doped with zirconium, and an atomic ratio of Zr(Si+Zr) may be in a range of 10 % to 50 %. The doped zirconium may increase a refractive index of the dielectric layer and thus improve transmittance. A total thickness of the lower anti-reflection film 20 consisting of the lower dielectric layer 21 and the upper dielectric layer 22 may be in the range of 30 nm to 45 nm. In addition, in order to improve the transmittance of the dielectric layer, the upper dielectric layer 22 doped with the zirconium may be preferably formed to be thicker than the lower dielectric layer 21, but is not limited thereto. Furthermore, when the upper dielectric layer 22 is thicker, surface roughness of the metal functional layer 40 may be reduced, and accordingly, there may be an advantage of reducing sheet resistance and thus lowering the emissivity. Herein, a thickness ratio of the upper dielectric layer 22 to the lower dielectric layer 21 may be in the range of 3:1 to 2:1, but is not particularly limited thereto.

The upper anti-reflection film 60 may include silicon nitride (Si₃N₄). In addition, as shown in FIG. 1, the upper anti-reflection film 60 may be a single layer or a stack of two or more layers, but is not particularly limited thereto. Furthermore, the upper anti-reflection film 60 may be formed directly on the upper metal protective layer 50 in direct contact with the upper metal protective layer 50. The upper anti-reflection film 60 may have a thickness of greater than or equal to 30 nm, and specifically, 35 nm to 50 nm. In addition, the upper anti-reflection film 60 may be thicker than the lower anti-reflection film 20, and for example, a thickness ratio of the upper anti-reflection film 60 to the lower anti-reflection film 20 may be in the range of 1.1:1 to 1.4:1. In this way, the thickness ratio of the upper anti-reflection film 60 to the lower anti-reflection film 20 may be controlled to adjust the reflection color of the multilayer thin film coating and to simultaneously increase transmittance.

In addition, the lower anti-reflection film 20 and the upper anti-reflection film 60 may be additionally doped with aluminum and the like. The doped aluminum may contribute to easily forming the dielectric layer during the manufacturing process. In addition, various doping agents, for example, fluorine, carbon, nitrogen, boron, phosphorus, and the like in addition to the zirconium and the aluminum may be used to increase a formation speed of the dielectric layer by sputtering as well as to improve optical properties of the film.

The metal functional layer 40 may have an infrared (IR) reflection characteristic. The metal functional layer 40 may include at least one of gold (Ag), copper (Cu), palladium (Pd), aluminum (Al), and silver (Ag). Specifically, the silver or a silver alloy may be included. The silver alloy may include a silver-gold alloy and a silver-palladium alloy. The metal functional layer 40 may be 12 nm to 18 nm thick. When the thickness is too thin, a solar heat gain coefficient (SHGC) may be increased. When the thickness is too thick, color coordinates of a transmissive color may be farther away from blue.

In an embodiment of the present invention, the lower metal protective layer 30 and the upper metal protective layer 50 are respectively at the bottom and the top of the metal functional layer 40. In other words, the lower metal protective layer 30 may be disposed between the lower anti-reflection film 20 and the metal functional layer 40, and the upper metal protective layer 30 may be disposed between the upper anti-reflection film 60 and the metal functional layer 40. The lower metal protective layer 30 and the upper metal protective layer 50 may prevent oxidization and corrosion of the metal functional layer 70.

Accordingly, in order to maximize the oxidization-preventing effect, the lower metal protective layer 30 and the upper metal protective layer 50 may be formed to be thicker, however it may deteriorate transmittance of the transparent substrate 100 with the multilayer thin film coating and increase emissivity thereof. Therefore, in an embodiment of the present invention, the lower metal protective layer 30 and the upper metal protective layer 50 may have a total thickness of 0.6 nm to 2.25 nm. When the total thickness of the lower metal protective layer 30 and the upper metal protective layer 50 is less than 0.6 nm, the metal functional layer 70 may hardly be prevented from corroding, and when the total thickness of the lower metal protective layer 30 and the upper metal protective layer 50 is greater than 2.25 nm, transmittance is decreased, and emissivity is increased, which may deteriorate properties of the transparent substrate.

In addition, in an embodiment of the present invention, the lower metal protective layer 30 may be thicker than the upper metal protective layer 50. When the lower metal protective layer 30 is thicker than the upper metal protective layer 50, durability, particularly chemical durability, may be much increased. Since the multilayer thin film coating 120 is on the formed transparent substrate 100, stress may be applied to the upper anti-reflection film 60 on top, and resultantly, the multilayer thin film coating 120 may be mainly peeled off at the bottom of the stacking structure, that is, at the near side to the transparent substrate 110. In an embodiment of the present invention, when the lower metal protective layer 30 is thicker than the upper metal protective layer 50, the corrosion and peeling at the near side of the transparent substrate 110 may be effectively prevented, and accordingly, excellent durability may be obtained, compared with when the lower metal protective layer 30 having the same total thickness as the upper metal protective layer 50. As a result, low-E performance of the multilayer thin film coating 120, that is, low emissivity and high transmittance, may be accomplished, and simultaneously, durability of the multilayer thin film coating 120 may be improved by suppressing corrosion and peeling thereof.

The thickness of the lower metal protective layer 30 may be 0.5 nm to 1.3 nm, and the thickness of the upper metal protective layer 50 may be 0.2 nm to 0.6 nm. A ratio of the thickness of the lower metal protective layer 30 to the total thickness of the lower metal protective layer 30 and the upper metal protective layer 50 may be greater than 0.5 and smaller than 1. Preferably, the ratio may be greater than 0.6 and smaller than 0.8.

The lower metal protective layer 30 and the upper metal protective layer 50 may respectively include at least one selected from titanium, nickel, chromium, and niobium. Specifically, a nickel-chromium alloy may be included.

In addition, the multilayer thin film coating 120 may further include the overcoat 70 at the outermost. In other words, the overcoat 70 may be included on the upper metal protective layer 50, that is, on one side away from the transparent substrate 110. The overcoat 70 may include at least one selected from zirconium-doped titanium oxide (TiZrO), zirconium-doped titanium nitride (TiZrN), zirconium-doped titanium oxynitride (TiZrON), zirconium oxide (ZrO), zirconium nitride (ZrN), and zirconium oxynitride (ZrON). Preferably, the overcoat 70 may include TiZrO. When this overcoat 70 is included, layers included in the multilayer thin film coating 120 may be prevented from damage. The overcoat 70 may have a thickness of 2 nm to 5 nm.

Because of the aforementioned configuration, in an embodiment of the present invention, the transparent substrate 100 with the multilayer thin film coating 120 has excellent characteristics in terms of emissivity, transmittance, durability, reflectance, and color.

In other words, visible light transmittance (TL) may be in the range of 70 % to 80 %, and coating surface reflectance may be less than 10 %. Normal emissivity may be in the range of 0.03 to 0.05. In CIELAB color coordinates, the coated surface may have a reflective color of 5 ≤ a* ≤ 10 and -20 ≤ b* ≤ -10. Corrected emissivity may be 0.036 to 0.059.

In addition, a ratio of visible light transmittance to normal emissivity (= visible light transmittance/normal emissivity) may be greater than 14, and when this transparent substrate 100 is dipped in an aqueous solution of 0.1 N of H₂SO₄ + 10 wt% of NaCl at room temperature, the transparent substrate may have no visible corrosion found with the naked eye for greater than or equal to 168 hours.

FIG. 2 is a view showing a cross-section of a multiple glazing unit 200 according to an embodiment of the present invention.

The multiple glazing unit 200 of FIG. 2 is for illustrative purposes only, and the present invention is not limited thereto. Accordingly, the multiple glazing unit 200 of FIG. 2 may be modified in various forms.

As shown in FIG. 2, a multiple glazing unit 200 according to an embodiment of the present invention includes at least two transparent substrates 110 and 140, and at least one of the two or more transparent substrates may be the transparent substrate 100 with the aforementioned multilayer thin film coating 120. The multiple glazing unit 200 includes two or more transparent substrates held by a spacer 150, and at least one gas separation interface 130 disposed between two substrates. In FIG. 2, the transparent substrate 140 is shown to have no separate thin film in addition to the transparent substrate 100 with the multilayer thin film coating 120, but the same multilayer thin film coating 120 may be formed on, under, or on both thereof, or a different thin film therefrom may be formed.

The multiple glazing unit 200 according to an embodiment of the present invention may exhibit improved durability, as described above, since the multilayer thin film coating 120 is configured to form the metal protective layer on both surfaces of a metal functional layer, wherein the metal protective layer disposed on the side of the transparent substrate 110, that is, on the lower metal protective layer, is formed to be thicker than the upper metal protective layer formed at the opposite side thereof and thus may efficiently prevent corrosion and peeling of the multilayer thin film coating 120, even though the end of the multilayer thin film coating 120 is exposed to the open air.

Hereinafter, the present invention will be described in more detail through experimental examples. However, these experimental examples are for illustrative purposes only, and the present invention is not limited thereto.

Experimental Examples

A lower anti-reflection film/a lower metal protective layer/a metal functional layer/an upper metal protective layer/an upper anti-reflection film in order were stacked on a transparent substrate to form a transparent substrate with a multilayer thin film coating.

The transparent substrate was a 5 mm-thick glass substrate (Tradename: HanLite Clear, Hanglas Co., Ltd.). As for the lower anti-reflection film, a Si₃N₄ layer was formed to be 35 nm thick, and as for the lower metal protective layer, a NiCr layer was formed to have a different thickness, as shown Table 1. As for the metal functional layer, a Ag layer was formed to be 13 nm thick, and as for the upper metal protective layer, a NiCr layer was formed to have a different thickness, as shown in Table 1. As for the upper anti-reflection film, a Si₃N₄ layer was formed to be 40 nm thick.

	Comparative Example 1	Comparative Example 2	Example 1	Example 2
Thickness of upper metal protective layer (NiCr) (nm)	0.2	0.6	0.2	0.4
Thickness of lower metal protective layer (NiCr) (nm)	0.2	0.2	0.6	1
Total thickness of upper and lower metal protective layers	0.4	0.8	0.8	1.4

The transparent substrates with the multilayer thin film coating, which had the stacking structure shown in Table 1 according to examples and comparative examples, were measured with respect to visible light transmittance and corrected emissivity. In addition, durability thereof was tested by dipping each transparent substrate in an aqueous solution of 0.1 N of H₂SO₄ + 10 wt% of NaCl at room temperature, and then measuring time when each transparent substrate exhibited visible corrosion with the naked eye (dipping test). In addition, when allowed to stand at 40 °C under relative humidity of 100 % , time when the transparent substrate was corroded was also measured (high temperature and high humidity test). The results are shown in Table 2 and FIGS. 3 and 4.

	Comparative Example 1Sample 1	Comparative Example 2 Sample 2	Example 1Sample 3	Example 2Sample 4
Transmittance (%)	82	78	78	74
Corrected emissivity (%)	8	10	10	12
Dipping test	1 day	2 days	7 daysor more (*)	7 daysor more
High-temperature and high-humidity test	5 days	7 days	28 daysor more	28 daysor more

* “7 days or more” and “28 days or more” mean that since a sample was not corroded after allowed to stand for 7 days and 28 days, the test was finished. As shown in Table 2, when the upper and lower metal protective layers had the same thickness (Comparative Example 1), or the upper metal protective layer was formed to be thicker than the lower metal protective layer (Comparative Example 2), sufficient durability was not obtained. In other words, in Comparative Example 1, visible corrosion was observed with the naked eye in 1 day for the dipping test and in 5 days for the high-temperature and high-humidity test, and in Comparative Example 2, visible corrosion was observed with the naked eye in 2 days for the dipping test and in 7 days for the high-temperature and high-humidity test. On the contrary, in Examples 1 and 2 wherein the lower metal protective layer was formed to be thicker than the upper metal protective layer, satisfactory transmittance and corrected emissivity were not only maintained, but also no corrosion was identified with the naked eye even in 7 days for the dipping test and even in 28 days for the high-temperature and high-humidity test. FIG. 3 is a photograph showing the state of each sample 7 days after the start of the dipping test, and FIG. 4 is a photograph showing the state of each sample 28 days after the start of the high-temperature and high-humidity test.

As shown in FIG. 3, in Samples 1 and 2, that is, in Comparative Examples 1 and 2, corrosion was identified at the bottom of the photo, but in Samples 3 and 4, that is, in Examples 1 and 2, no change was observed. In addition, as shown in FIG. 4, even in the high-temperature and high-humidity test, Samples 1 and 2 exhibited corrosion and a color change, but Samples 3 and 4 exhibited almost no corrosion and color change. △E representing a degree of the color change exhibits a color difference before and after the experiment in CIELAB color coordinates.

In addition, durability of a multiple glazing unit including the transparent substrate with a multilayer thin film coating was tested as follows.

That is, a 12 mm-thick gas separation interface and a spacer were disposed between each transparent substrate of Comparative Examples 1 and 2 and Examples 1 and 2 and a 5 mm-thick glass substrate (Tradename: HanLite Clear, HanGlas Co., Ltd.) to manufacture a double glazing unit.

Each double glazing unit referred to as Comparative Examples 3 and 4 and Examples 3 and 4 were tested. First, the double glazing units were allowed to stand in the open air and measured with respect to time when corrosion occurred (a field test). In addition, 7.5 wt% of a NaCl aqueous solution was continuously sprayed -on the double glazing unit at 60 °C to measure time when corrosion occurred (a spray test), and the double glazing unit was dipped in a 5 wt% NaCl aqueous solution at 50 °C to measure time when corrosion occurred (a dipping test). The results are shown in Table 3 and FIGS. 5 and 6.

	Comparative Example 3(Sample 1)	Comparative Example 4 (Sample 2)	Example 3(Sample 3)	Example 4(Sample 4)
Transparent substrate with a multilayer thin film coating	Comparative Example 1	Comparative Example 2	Example 1	Example 2
Field test	2 months	-	2 yearsor more	2 yearsor more
Spray test	3 days	69 days	125 daysor more	125 daysor more
Dipping test	3 days	80 days	125 daysor more	125 daysor more

As shown in Table 3, in Comparative Example 3, corrosion was identified in just 2 months for the field test and in 3 days for the spray test and the dipping test, and in Comparative Example 4, there were no data in the field test, but corrosion was identified with the naked eye in 69 days and 80 days respectively for the spray test and the dipping test. On the contrary, as for Examples 3 and 4, no corrosion was identified with the naked eye in 2 years or more for the field test and in 125 days for the spray test and the dipping test. FIG. 5 is a photograph showing the state of each sample after a certain period of time after the start of the field test, and FIG. 6 is a photograph showing the state of each sample after a certain period of time after the start of the spray test. As shown in FIG. 5, as for Sample 1, that is, Comparative Example 3, corrosion was identified in about 2 months at the edge, as marked by the red quadrangle, and as shown in the enlarged view at the right, the corrosion state was clearly confirmed with the naked eye. However, Samples 3 and 4, that is, Examples 3 and 4, exhibited no change even in 2 years. In addition, as shown in FIG. 6, Samples 1 and 2 individually exhibited corrosion in 10 days and 70 days for the spray test, but Samples 3 and 4 exhibited no corrosion even in 2 years.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Therefore, the embodiments described above are only examples and should not be construed as being limitative in any respects.

100: transparent substrate with a multilayer thin film coating

110: transparent substrate

120: multilayer thin film coating

20: lower anti-reflection film

30: lower metal protective layer

40: metal functional layer

50: upper metal protective layer

60: upper anti-reflection film

70: overcoat

200: multiple glazing unit

Claims

A transparent substrate with a thin film multilayer coating comprising

a transparent substrate; and

a multilayer thin film coating, wherein the multilayer thin film coating includes a lower anti-reflection film, a lower metal protective layer, a metal functional layer having an infrared reflecting function, an upper metal protective layer, and an upper anti-reflection film sequentially stacked from the transparent substrate,

wherein each of the upper anti-reflection film and the lower anti-reflection film includes at least one dielectric layer, the upper anti-reflection film includes a silicon nitride-based dielectric layer, and the silicon nitride-based dielectric layer is stacked in direct contact with the upper metal protective layer and has a thickness of greater than or equal to 30 nm,

a sum of the thickness of the lower metal protective layer and the upper metal protective layer is 0.6 nm to 2.25 nm, and

a thickness of the lower metal protective layer is greater than that of the upper metal protective layer.
The transparent substrate with a thin film multilayer coating of claim 1, wherein

an overcoat is further included on one surface of the upper antireflection film in a direction away from the transparent substrate, and

the overcoat includes at least one selected from zirconium-doped titanium oxide (TiZrO), zirconium-doped titanium nitride (TiZrN), zirconium-doped titanium oxynitride (TiZrON), zirconium oxide (ZrO), zirconium nitride (ZrN), and zirconium oxynitride (ZrON).
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein the lower metal protective layer has a thickness of 0.5 nm to 1.3 nm.
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein the upper metal protective layer has a thickness of 0.2 nm to 0.6 nm.
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein the metal functional layer has a thickness of 12 nm to 18 nm.
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein each of the upper metal protective layer and the lower metal protective layer includes at least one of titanium, nickel, chromium, and niobium, or an alloy thereof.
The transparent substrate with a thin film multilayer coating of claim 6, wherein each of the upper metal protective layer and the lower metal protective layer includes a nickel-chromium alloy.
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein the lower anti-reflection film includes a silicon nitride.
The transparent substrate with a thin film multilayer coating of claim 8, wherein each of the lower anti-reflection film and the upper anti-reflection film further includes at least one nitride, oxide, or oxynitride selected from titanium (Ti), hafnium (Hf), zirconium (Zr), and aluminum (Al).
The transparent substrate with a thin film multilayer coating of claim 8, wherein

the lower anti-reflection film includes a lower dielectric layer disposed on the transparent substrate and an upper dielectric layer disposed on the lower dielectric layer, and

the lower dielectric layer further includes doped zirconium.
The transparent substrate with a thin film multilayer coating of claim 8, wherein

the lower anti-reflection film has a thickness of 30 nm to 45 nm, and

the upper anti-reflection film has a thickness of 35 nm to 50 nm.
The transparent substrate with a thin film multilayer coating of claim 11, wherein a thickness ratio of the upper anti-reflection film to the lower anti-reflection film is greater than or equal to 1.1 and less than or equal to 1.4.
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein a thickness ratio of the lower metal protective layer to a total thickness of the lower metal protective layer and the upper metal protective layer (lower/(lower + upper)) is greater than 0.5 and less than 1.
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein a ratio of visible light transmittance to normal emissivity (= visible light transmittance/normal emissivity) is greater than 14.
The transparent substrate with a thin film multilayer coating of claim 14, wherein when dipped in an aqueous solution of 0.1 N of H₂SO₄ and 10 wt% of NaCl at room temperature, a time until which visible corrosion does not occur is greater than or equal to 168 hours.
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein the visible light transmittance (TL) is 70 % to 80 %.
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein coating surface reflectance is less than 10 %.
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein in CIELAB color coordinates, the coated surface has a reflective color of 5 ≤ a* ≤ 10 and -20 ≤ b* ≤ -10.
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein normal emissivity is 0.03 to 0.05.
The transparent substrate with a thin film multilayer coating of claim 1 or claim 2, wherein sheet resistance of the multilayer thin film coating is less than 4.0 Ω/square.
A multiple glazing unit, comprising

at least two transparent substrates with a thin film multilayer coating spaced apart from each other with a spacer therebetween,

wherein at least one of the at least two transparent substrates with a thin film multilayer coatings is the transparent substrate with a multilayer thin film coating of claim 1.