Low-emissivity glass

Abstract

The present invention relates to a low-emission glass having a glass substrate, a first dielectric layer, a first metal protective layer, a first infrared reflective layer, a second metal protective layer, a second dielectric layer, a metal absorption layer, a third dielectric layer, a third metal protective layer, a second infrared reflective layer, a fourth metal protective layer, a fourth dielectric layer, and an overcoat layer sequentially stacked, wherein the thickness ratio of the first infrared reflective layer and the second infrared reflective layer is 1.0:2.2 to 1.0:2.7, the thickness of the first dielectric layer is 31 nm to 34 nm, and the thickness ratio of the second dielectric layer and the third dielectric layer is 1.75:1.0 to 1.97:1.0.

Description

Technology Field

[0001] The present invention relates to low-emissivity glass having low emissivity, external reflectivity, and internal reflectivity, and being achromatic. Background Technology

[0002] Low-emissivity glass is a functional building material created by depositing a metal with high reflectivity in the infrared region, such as silver (Ag), onto transparent glass. This maintains the transparency of the glass while blocking indoor heating heat from escaping to the outside during winter and reflecting solar radiation entering the interior during summer. Although the initial use of such low-emissivity glass prioritized improved thermal insulation performance and ease of handling, requirements regarding the exterior color and light reflectivity of buildings have increased since the widespread adoption of low-emissivity glass. Furthermore, there is a continuous demand for improved thermal insulation performance to reduce energy consumption for heating and cooling in buildings.

[0003] However, in order to improve thermal insulation performance, it is essential to increase the thickness of the silver (Ag) material that makes up the low-emissivity glass, which increases external reflectivity and causes the color to appear strongly blue, making it impossible to satisfy the requirements for a beautiful exterior of the building.

[0004] Therefore, there is a need for research and development on low-emissivity glass that prevents glare caused by external reflectivity in the emissivity range (emissivity 0.005 or less) where thermal insulation performance is maximized, and applies an external color in the achromatic range (gray). Prior art literature

[0005] Korean Registered Patent No. 10-1979625 (Publication Date: 2016.01.27) The problem to be solved

[0006] The present invention aims to solve the above-mentioned problems by providing low-emissivity glass having an emissivity of 0.005 or less, a colorless glass, a visible light transmittance of 20% to 50%, an external reflectance of 10% to 20%, and a visible light internal reflectance of 40% or less. means of solving the problem

[0007] The present invention provides a low-emissivity glass having a glass substrate, a first dielectric layer, a first metal protective layer, a first infrared reflective layer, a second metal protective layer, a second dielectric layer, a metal absorption layer, a third dielectric layer, a third metal protective layer, a second infrared reflective layer, a fourth metal protective layer, a fourth dielectric layer, and an overcoat layer sequentially stacked, wherein the thickness ratio of the first infrared reflective layer and the second infrared reflective layer is 1.0:2.2 to 1.0:2.7, the thickness of the first dielectric layer is 31 nm to 34 nm, and the thickness ratio of the second dielectric layer and the third dielectric layer is 1.75:1.0 to 1.97:1.0.

[0008] The sum of the thicknesses of the first infrared reflective layer and the second infrared reflective layer may be 36 nm to 39 nm.

[0009] In addition, the thickness of the first infrared reflective layer may be 9.7 nm to 11.3 nm, and the thickness of the second infrared reflective layer may be 24.5 nm to 28.5 nm.

[0010] The sum of the thicknesses of the second dielectric layer and the third dielectric layer may be 87.5 nm to 92.5 nm.

[0011] The thickness of the fourth dielectric layer may be 28 nm to 32 nm.

[0012] The first infrared reflective layer and the second infrared reflective layer may include one or more selected from the group consisting of Ag, Cu, Au, Al, and Pt.

[0013] The first to fourth dielectric layers may each independently include one or more nitrides or oxides selected from the group consisting of Zn, Ti, Si, Nb, Sn, Al, Zr, and Ta.

[0014] Specifically, the first to fourth dielectric layers may include silicon-aluminum nitride or silicon-zirconium nitride.

[0015] The low-emissivity glass according to the present invention has an emissivity of 0.005 or less as measured according to KS L 2525, and the low-emissivity glass may have an a* value of 0 to -3 and a b* value of -3 to -11 in CIE lab color coordinates.

[0016] In addition, the low-emissivity glass according to the present invention may have a transmittance of 20% to 50% at a wavelength of 380 to 780 nm as measured according to KS L 2514, an external reflectance of 10% to 20% at a wavelength of 380 to 780 nm as measured according to KS L 2514, and an internal reflectance of 40% or less at a wavelength of 380 to 780 nm as measured according to KS L 2514. Effects of the invention

[0017] The low-emissivity glass according to the present invention has excellent shielding and thermal insulation performance with a low emissivity of 0.005 or less, and at the same time has an external reflectance of visible light of 20% or less, which can prevent glare caused by light reflection from the outside, and is suitable as a building material for suppressing glare from the opposite side of a building in commercial areas that require high thermal insulation performance and a beautiful appearance with a neutral color expression. Specific details for implementing the invention

[0018] The present invention will be described in detail below.

[0019] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0020] Additionally, in this specification, when it is stated that a component is located "on" another component, this includes not only cases where a component is in contact with another component, but also cases where another component exists between the two components.

[0021] Furthermore, in this specification, "transmittance" means a value calculated according to the KS L 2514 standard by measuring the transmission spectrum in the wavelength range of 380 to 780 nm using a spectrophotometer.

[0022] In addition, in this specification, "reflectance" means a value calculated according to the KS L 2514 standard by measuring the reflection spectrum in the wavelength range of 380 to 780 nm using a spectrophotometer.

[0023] In addition, in this specification, "a" of glass * value" and "b * The "value" is the a of the glass surface measured according to KS L 2514 using a D65 standard light source in the wavelength range of 380 to 780 nm, based on an average glass substrate thickness of 6 mm. * value and b * It means value.

[0025] The low-emissivity glass according to the present invention comprises a glass substrate, a first dielectric layer, a first metal protective layer, a first infrared reflective layer, a second metal protective layer, a second dielectric layer, a metal absorption layer, a third dielectric layer, a third metal protective layer, a second infrared reflective layer, a fourth metal protective layer, a fourth dielectric layer, and an overcoat layer sequentially stacked, wherein the thickness ratio of the first infrared reflective layer and the second infrared reflective layer is 1.0:2.2 to 1.0:2.7, the thickness of the first dielectric layer is 31 nm to 34 nm, and the thickness ratio of the second dielectric layer and the third dielectric layer is 1.75:1.0 to 1.97:1.0.

[0026] Conventional low-emissivity glass provides a thermal insulation effect by depositing silver (Ag), which has high reflectivity in the infrared region, onto the glass. To improve thermal insulation performance, the thickness of the silver must be increased, but there is a disadvantage that the color of the glass changes to a chromatic color as the thickness of the silver increases. However, the low-emissivity glass according to the present invention can achieve excellent thermal insulation performance while enabling the realization of achromatic colors by adjusting the thickness ratio of the first infrared reflective layer and the second infrared reflective layer and the thickness ratio of the second dielectric layer and the third dielectric layer, thereby reducing emissivity and visible light reflectivity.

[0028] The following describes in detail each component of the low-emissivity glass according to the present invention.

[0030] glass substrate

[0031] The glass substrate serves as the base substrate for the low-emissivity glass.

[0032] At this time, the glass substrate may be a conventional glass such as soda-lime glass, low-iron glass, green glass, or blue glass used for construction or automobiles.

[0033] In addition, glass of an appropriate thickness may be used as the glass substrate depending on the purpose of use. For example, transparent soda-lime glass with an average thickness of 2 to 12 mm or 5 to 6 mm may be used as the glass substrate.

[0035] 1st to 4th dielectric layers

[0036] Each of the first to fourth dielectric layers serves to control the optical properties of the manufactured glass by blocking ions or oxygen transferred to the infrared reflective layer during heat treatment.

[0037] The first to fourth dielectric layers may each include a structure in which one or more dielectric layers are stacked independently. Specifically, the first to fourth dielectric layers may each include a structure in which one to four dielectric layers are stacked independently.

[0038] The first to fourth dielectric layers may each independently comprise one or more nitrides or oxides selected from the group consisting of Zn, Ti, Si, Nb, Sn, Al, Zr, and Ta. Specifically, the first to fourth dielectric layers may each independently comprise silicon nitride or silicon-zirconium nitride.

[0039] Specifically, the first to fourth dielectric layers are each independently SiAlN x or SiZrN y It may include, wherein x may be between 0.5 and 1.5, and y may be greater than 0.5 and less than 1.4. When x and y are within the above range, a dielectric layer that does not contain metal is formed, thereby enabling the realization of the desired properties of low-emissivity glass. If it falls outside the above range, a dielectric layer containing metal is formed, which may result in a decrease in visible light transmittance or the realization of a color other than the desired color.

[0040] The first to fourth dielectric layers may each independently have a refractive index of 1.8 or higher, 1.8 to 2.5, or 1.8 or higher and less than 2.3. Additionally, the first to fourth dielectric layers may each independently have an absorption coefficient of 0.1 or lower, or greater than 0 and less than 0.1. When the refractive index and absorption coefficient of each of the first to fourth dielectric layers are within the above ranges, the problem of reduced visible light transmittance of the manufactured glass, which impairs the visual field, can be prevented.

[0041] Meanwhile, the thickness ratio of the second dielectric layer and the third dielectric layer is stacked in a ratio of 1.75:1.00 to 1.97:1.00, 1.80:1.00 to 1.95:1.00, or 1.85:1.00 to 1.93:1.00. If the ratio of the third dielectric layer increases, the color on the front and side may appear reddish, and the external reflectance of visible light may exceed 20%. If the ratio of the second dielectric layer increases, the color on the front and side may change to a greenish hue. Within the above thickness ratios, the external reflectance of visible light of the low-emissivity glass may be 20% or less and may have an achromatic color.

[0042] Additionally, the thickness of the first dielectric layer may be 31 nm to 34 nm or 31 nm to 33 nm. The thickness of the fourth dielectric layer may be 28 nm to 32 nm or 29 nm to 31 nm. If the thickness of the first dielectric layer falls outside the above range, the wavelength in the 400-500 nm region changes, causing red or green to appear, making it difficult to achieve the target achromatic gray color. If the thickness of the fourth dielectric layer falls outside the above range, it is difficult to adjust the transmittance and color b* in the desired region.

[0043] The sum of the thicknesses of the second dielectric layer and the third dielectric layer may be 87.5 nm to 92.5 nm, 88.0 nm to 92.0 nm, or 89.0 nm to 91.0 nm. If the sum of the thicknesses of the second dielectric layer and the third dielectric layer falls outside the above range, the light interference phenomenon changes, the reflectance of visible light increases, and a color difference between the front and the side may occur.

[0045] First metal protective layer to fourth metal protective layer

[0046] The first to fourth metal protective layers are each positioned between the reflective layer and the infrared reflective layer to improve adhesion and block the movement of sodium (Na) and oxygen (O2) in the air that diffuse from the glass during heat treatment, or oxygen (O2) that diffuses during the step of depositing the dielectric layer. In addition, each of the first to fourth metal protective layers helps to fuse the metal within the infrared reflective layer so that the infrared reflective layer can behave stably even at high heat treatment temperatures, and helps to maintain the low-emissivity performance of the glass by absorbing oxygen (O2) that penetrates into the infrared reflective layer.

[0047] The first to fourth metal protective layers may each independently comprise one or more selected from the group consisting of nickel (Ni), chromium (Cr), titanium (Ti), and nickel (Ni)-chromium (Cr) alloys. Specifically, the first to fourth metal protective layers may use a nickel-chromium alloy.

[0049] First infrared reflective layer and second infrared reflective layer

[0050] The first infrared reflective metal layer and the second infrared reflective metal layer each selectively reflect solar radiation to improve the solar heat shielding performance of the manufactured glass and simultaneously achieve low radiation.

[0051] The first infrared reflective layer and the second infrared reflective layer may each independently include a metal with excellent conductivity, for example, one or more metals selected from the group consisting of gold, silver, platinum, aluminum, and copper. Specifically, the first infrared reflective layer and the second infrared reflective layer may include silver (Ag). More specifically, the first infrared reflective layer and the second infrared reflective layer may be made of silver.

[0052] Meanwhile, the thickness ratio of the first infrared reflective layer and the second infrared reflective layer may be 1.0:2.2 to 1.0:2.7, 1.0:2.3 to 1.0:2.6, or 1.0:2.4 to 1.0:2.5. Within the above thickness ratio range, the low-emissivity glass may exhibit a color in the achromatic series. If the thickness ratio of the first infrared reflective layer increases, the blue tint appearing on the outside of the low-emissivity glass may become too strong, and an achromatic series may not be imparted. If the thickness ratio of the second infrared reflective layer increases, the external reflectance of visible light may exceed 20%.

[0053] Additionally, the sum of the thicknesses of the first infrared reflective layer and the second infrared reflective layer may be 36 nm to 39 nm, 36 nm to 38 nm, or 36 nm to 37 nm. If the sum of the thicknesses exceeds the above range, the color of the low-emissivity glass may appear bluish, making it difficult to achieve a neutral color, and the transmittance of visible light may decrease. If the sum of the thicknesses is less than the above range, the emissivity of the low-emissivity glass may exceed 0.005, and the thermal insulation function may be degraded.

[0054] The thickness of the first infrared reflective layer may be 9.7 nm to 11.3 nm or 10.0 nm to 11.0 nm. The thickness of the second infrared reflective layer may be 24.5 nm to 28.5 nm or 25 nm to 28 nm. If the thicknesses of the first infrared reflective layer and the second infrared reflective layer are within the above ranges, problems such as insufficient low-emissivity and thermal insulation performance of the manufactured glass due to abnormal formation of the infrared reflective layer, and reduced durability due to oxidation of the metal within the infrared reflective layer can be prevented. If the thicknesses of the first infrared reflective layer and the second infrared reflective layer are less than the above ranges, problems such as insufficient low-emissivity and thermal insulation performance of the manufactured glass may occur, and if they exceed the above ranges, problems such as reduced durability of the manufactured glass may occur.

[0056] First metal absorption layer

[0057] The first metal absorption layer serves to increase the absorption rate in the visible light region.

[0058] The first metal absorption layer uses a metal material to lower the reflectance of the glass surface by increasing the absorption rate in the visible light region.

[0059] The first metal absorption layer may each independently include one or more selected from the group consisting of nickel (Ni), chromium (Cr), titanium (Ti), and nickel (Ni)-chromium (Cr) alloy. Specifically, a nickel-chromium alloy may be used as the first metal absorption layer.

[0061] Overcoat layer

[0062] The overcoat layer serves to protect the dielectric protective layer from physical and thermal damage. Specifically, the overcoat layer has low hardness, allowing it to absorb external shocks and protect the dielectric layer and infrared reflective layer by sacrificing thermal damage.

[0063] The above overcoat layer may include a material that has low visible light transmittance before heat treatment but completely disappears after heat treatment and does not affect optical properties, and specifically, may include a carbon layer.

[0064] The overcoat layer may include a material having high mechanical strength, low surface roughness, and high visible light transmittance. For example, the overcoat layer may include one or more selected from the group consisting of metal oxides, metal nitrides, and metal nitrides. In this case, the metals that may be included in the overcoat layer may include oxides, nitrides, or nitrides of one or more metals selected from the group consisting of silicon (Si), niobium (Nb), titanium (Ti), zirconium (Zr), and tantalum (Ta). Specifically, the overcoat layer may include titanium nitride or titanium nitride.

[0065] At this time, the titanium nitrate is TiO a N b It is represented as such, where a is 1.5 to 1.9 or 1.6 to 1.8, and b is 0.2 to 0.5 or 0.3 to 0.4. If a is within the above range, the problem of reduced durability of the manufactured glass can be prevented, and if b is within the above range, the problem of reduced visible light transmittance of the manufactured glass can be prevented.

[0067] The low-emissivity glass according to the present invention may have an emissivity of 0.005 or less as measured according to KS L 2525. Emissivity refers to the ratio of energy that is partially re-radiated or re-radiated when surface reflection occurs after absorbing external light energy, and the maximum value is 1, and the smaller the value, the greater the ratio of re-radiated or re-radiated energy.

[0068] In addition, the low-emissivity glass according to the present invention is a of the CIE lab color coordinates * The value is 0 to -3 and b * The value may be -3 to -11. Within the above range, the low-emissivity glass may be achromatic.

[0069] In addition, the low-emissivity glass according to the present invention may have a transmittance of 20% or more or 20% to 50% at a wavelength of 380 to 780 nm as measured according to KS L 2514, an external reflectance of 20% or less or 10% to 20% at a wavelength of 380 to 780 nm as measured according to KS L 2514, and an internal reflectance of 40% or less or 30% to 40% at a wavelength of 380 to 780 nm as measured according to KS L 2514.

[0071] The present invention will be explained in more detail below through specific embodiments. However, these embodiments are intended only to aid in understanding the invention and do not limit the scope of the invention in any way to these embodiments.

[0073] <Example>

[0074] Example 1. Preparation of low-emissivity glass

[0075] A low-emission glass was manufactured in the form of sequentially stacked glass substrate, a first dielectric layer, a first metal protective layer, a first infrared reflective layer, a second metal protective layer, a second dielectric layer, a first metal absorption layer, a third dielectric layer, a third metal protective layer, a second infrared reflective layer, a fourth metal protective layer, a fourth dielectric layer, and an overcoat layer.

[0076] Specifically, a first dielectric layer was coated on a 5 mm thick transparent glass substrate using a SiZr target under a nitrogen and argon atmosphere. Subsequently, a first metal protective layer was coated on the first dielectric layer using a Ni8Cr2 target under an argon atmosphere. Then, a first infrared reflective layer was coated on the first metal protective layer using an Ag target under an argon atmosphere. Subsequently, a second metal protective layer was coated in the same manner as the first metal protective layer as described above, and the second dielectric layer was coated in the same manner as the first dielectric layer, except that a SiAl target was used. A first metal absorption layer was coated on the second dielectric layer using a Ni8Cr2 target under an argon atmosphere, and a third dielectric layer was coated using a SiAl target in the same manner as the first dielectric layer. Subsequently, a third metal protective layer was coated on the third dielectric layer using a Ni8Cr2 target under an argon atmosphere. Subsequently, a second infrared reflective layer was coated on the third metal protective layer using an Ag target under an argon atmosphere. Subsequently, the fourth metal protective layer was coated in the same manner as the third metal protective layer described above, and the fourth dielectric layer was coated using a SiAl target in the same manner as the third dielectric layer.

[0077] Subsequently, titanium oxide (TiO₂) on the fourth dielectric layer under an argon and nitrogen atmosphere x An overcoat layer was coated using a target, and an overcoat protective layer was coated on the overcoat layer using a carbon target under an argon atmosphere.

[0079] Examples 2 to 5 and Comparative Examples 1 to 20

[0080] Low-emissivity glass was manufactured in the same manner as in Experimental Example 1, except that the thickness and composition of each layer were controlled as described in Tables 1 to 3.

[0081] Thickness (nm) Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 overcoat 3 3 3 3 3 3 3 3 3 4th dielectric layer 30 27 33 30 30 30 30 30 30 4th metal protective layer 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 Second infrared reflective layer 26 26 26 26 26 26 26 26 26 Third metal protective layer 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Third dielectric layer 31 31 31 31 31 31 31 31 31 First metal absorption layer 4 4 4 3.6 4.4 4 4 4 4 Second dielectric layer 59 59 59 59 59 59 59 53 65 Second metal protective layer 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 First infrared reflective layer 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 10.5 First metal protective layer 3 3 3 3 3 3 3 3 3 1st dielectric layer 32 32 32 32 32 29 35 32 32 glass substrate 5 5 5 5 5 5 5 5 5

[0083] Thickness (nm) Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 overcoat 3 3 3 3 3 3 3 3 4th dielectric layer 30 30 30 30 30 30 30 25 4th metal protective layer 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 Second infrared reflective layer 26 26 26 26 23 29 26 27 Third metal protective layer 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Third dielectric layer 28 34 31 31 31 31 36 40.9 First metal absorption layer 4 4 4 4 4 4 4 4 Second dielectric layer 59 59 59 59 59 59 54 49.1 Second metal protective layer 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 First infrared reflective layer 10.5 10.5 9.5 11.5 10.5 10.5 10.5 10 First metal protective layer 3 3 3 3 3 3 3 3 1st dielectric layer 32 32 32 32 32 32 32 35 glass substrate 5 5 5 5 5 5 5 5

[0085] Thickness (nm) Comparative Example 13 Comparative Example 14 Comparative Example 15 Comparative Example 16 Comparative Example 17 Comparative Example 18 Comparative Example 19 Comparative Example 20 overcoat 3 3 3 3 3 3 3 3 4th dielectric layer 25 25 30 30 30 30 30 30 4th metal protective layer 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 Second infrared reflective layer 27 27 24.1 21.7 18.1 14.5 12.1 10.3 Third metal protective layer 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Third dielectric layer 45 49.1 31 31 31 31 31 31 First metal absorption layer 4 4 4 4 4 4 4 4 Second dielectric layer 45 40.9 59 59 59 59 59 59 Second metal protective layer 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 First infrared reflective layer 10 10 12.1 14.5 18.1 21.7 24.1 25.9 First metal protective layer 3 3 3 3 3 3 3 3 1st dielectric layer 35 35 32 32 32 32 32 32 glass substrate 5 5 5 5 5 5 5 5

[0087] <Experimental Example>

[0088] Experimental Example 1: Evaluation of Characteristics of Low-Emission Glass

[0089] The physical properties of the low-emissivity glasses prepared in Examples 1 to 5 and Comparative Examples 1 to 20 were measured in the following manner, and the results are shown in Table 4.

[0090] Specifically, the low-emissivity glass prepared in the experimental example was heat-treated at 720°C for 15 minutes using an electric furnace, and its physical properties were evaluated after natural cooling at room temperature.

[0091] (1) Visible light transmittance

[0092] Visible light transmittance was calculated according to KS L 2514 standard by measuring the transmission spectrum in the visible light wavelength range (380 to 780 nm) using a spectrophotometer (Lambda 1050, Perkinelmer).

[0093] (2) External reflectance of visible light

[0094] The external reflectance of visible light was calculated by measuring the reflection spectrum on the glass surface in the visible light wavelength range (380 to 780 nm) using a spectrophotometer (Spectrophotometer, Lambda 1050, Perkinelmer product) and using the KS L 2514 standard.

[0095] (3) Internal reflectance of visible light

[0096] The internal reflectance of visible light was calculated by measuring the reflection spectrum on the coating surface in the visible light wavelength range (380 to 780 nm) using a spectrophotometer (Spectrophotometer, Lambda 1050, Perkinelmer product) and according to KS L 2514 standard.

[0097] (4) Front color

[0098] The frontal colors were measured using a colorimeter (Colorimeter, CM9600-A, Minolta product) according to the CIE lab color coordinates specified by the CIE (International Commission on Illumination).

[0099] (5) Emissivity

[0100] Emissivity was calculated by measuring the spectral reflectance (ρn) at wavenumbers of 400 cm⁻¹ to 4,000 cm⁻¹ (wavelength range 2.5 μm to 25 μm) using an infrared spectrometer (FT-IR) and according to KS L 2514 and KS L 2525 standards. A gold-coated mirror was used as a standard material.

[0101] number transmittance External reflectance Internal reflectance Front color a* Front color b* emissivity Example 1 34.5 16.5 36.5 -1.7 -7.9 0.005 Example 2 32.6 17.6 39.8 -3 -6.5 0.005 Example 3 36.3 15.6 33.4 -0.3 -10.3 0.005 Example 4 35 17.2 36.4 -1.8 -7.5 0.005 Example 5 33.7 15.7 36.9 -1.7 -8.5 0.005 Comparative Example 1 34.1 17.3 37.3 -5.5 -8.1 0.005 Comparative Example 2 34.9 15.7 35.8 2.5 -8.9 0.005 Comparative Example 3 35.1 14 34.2 5.1 -5.3 0.005 Comparative Example 4 33 20.4 39.8 -6.3 -6.9 0.005 Comparative Example 5 35 15.5 35.5 0.9 -6.8 0.005 Comparative Example 6 33.9 17.8 37.7 -4.1 -8.4 0.005 Comparative Example 7 34 18 37.4 -1 -2.6 0.006 Comparative Example 8 35 15.3 35.6 -2.4 -13.1 0.004 Comparative Example 9 39.5 13.2 30.6 -1.8 -8.2 0.008 Comparative Example 10 29.6 19.9 42.4 -1.9 -7.8 0.003 Comparative Example 11 34.5 16.3 38.6 -3.2 -7.4 0.005 Comparative Example 12 34.8 15.1 33.5 2.7 -10 0.005 Comparative Example 13 35.2 17.2 31.3 2.2 -11.4 0.005 Comparative Example 14 36.1 19 30.3 0.3 -12.2 0.005 Comparative Example 15 38.1 12.8 31.5 -2.9 -16.2 0.005 Comparative Example 16 42.3 9.9 24.8 -4.4 -24.5 0.005 Comparative Example 17 44.2 12.8 19 -3.4 -20.4 0.005 Comparative Example 18 40.1 23.2 20.7 -0.9 -4.6 0.005 Comparative Example 19 34.8 32.4 26.1 0.1 5.4 0.005 Comparative Example 20 30.2 39.6 31.7 0.5 11.3 0.005

[0103] According to Table 4, it can be confirmed that the low-emissivity glass of Examples 1 to 5 has a visible light transmittance of 20% to 50%, an external visible light reflectance of 10% to 20%, an internal visible light reflectance of 40% or less, and a CIE lab color coordinate a* value of 0 to -3 and a b* value of -3 to -11.

[0104] On the other hand, it can be seen that Comparative Examples 1 and 2, in which the thickness of the first dielectric layer was controlled; Comparative Examples 3 and 4, in which the thickness of the second dielectric layer was controlled; Comparative Examples 5 and 6, in which the thickness of the third dielectric layer was controlled; Comparative Examples 7 and 8, in which the thickness of the first infrared reflective layer was controlled; and Comparative Examples 9 and 10, in which the thickness of the second infrared reflective layer was controlled, all failed to satisfy the target range of visible light external and internal reflectance or CIE lab color coordinate values.

[0105] In addition, Comparative Examples 4 to 7 have the sum of the thicknesses of the second dielectric layer and the third dielectric layer being 84 nm, 96 nm, 87 nm, and 93 nm, respectively. It can be confirmed that if the sum of the thicknesses of the second dielectric layer and the third dielectric layer deviates from 87.5 nm to 92.5 nm, the color of the low-emissivity glass is not realized as achromatic.

[0106] Comparative Examples 7 to 10 have a sum of thicknesses of the first infrared reflective layer and the second infrared reflective layer of 35.5 nm, 37.5 nm, 33.5 nm, and 39.5 nm, respectively. If the sum of the thicknesses of the first infrared reflective layer and the second infrared reflective layer is less than 36 nm, it can be confirmed that the emissivity of the low-emissivity glass is high.

[0107] Comparative Examples 11 to 14 all have a combined thickness of 90 nm for the second dielectric layer and the third dielectric layer, but the thicknesses of the second dielectric layer and the third dielectric layer are adjusted differently. It can be confirmed that Comparative Examples 11 to 14 all fail to satisfy the target range of CIE lab color coordinate values. Through this, it can be confirmed that even if the total thickness of the second dielectric layer and the third dielectric layer is the same, if the ratio of the thicknesses of the second dielectric layer and the third dielectric layer is not included in the range of 1.75:1.0 to 1.97:1.0, the low-emission glass does not exhibit achromaticity.

[0108] Comparative Examples 15 to 20 all have a combined thickness of 36.2 nm for the first infrared reflective layer and the second infrared reflective layer, but the thicknesses of the first infrared reflective layer and the second infrared reflective layer are adjusted differently. It can be confirmed that Comparative Examples 15 to 20 all fail to satisfy the target range of visible light external reflectance or CIE lab color coordinate values. Through this, it can be confirmed that even if the total thickness of the first infrared reflective layer and the second infrared reflective layer is the same, the required characteristics of low-emissivity glass cannot be satisfied if the thickness ratio of the first infrared reflective layer and the second infrared reflective layer is not included in the range of 1.0:2.2 to 1.0:2.7.

Claims

Claim 1 A low-emission glass having a glass substrate, a first dielectric layer, a first metal protective layer, a first infrared reflective layer, a second metal protective layer, a second dielectric layer, a metal absorption layer, a third dielectric layer, a third metal protective layer, a second infrared reflective layer, a fourth metal protective layer, a fourth dielectric layer, and an overcoat layer sequentially stacked, wherein the thickness ratio of the first infrared reflective layer and the second infrared reflective layer is 1.0:2.2 to 1.0:2.7, the thickness of the first dielectric layer is 31 nm to 34 nm, and the thickness ratio of the second dielectric layer and the third dielectric layer is 1.75:1.0 to 1.97:1.

0. Claim 2 A low-emissivity glass according to claim 1, wherein the sum of the thicknesses of the first infrared reflective layer and the second infrared reflective layer is 36 nm to 39 nm. Claim 3 In claim 1, the thickness of the first infrared reflective layer is 9.7 nm to 11.3 nm, and the thickness of the second infrared reflective layer is 24.5 nm to 28.5 nm, low-emissivity glass. Claim 4 A low-emission glass according to claim 1, wherein the sum of the thicknesses of the second dielectric layer and the third dielectric layer is 87.5 nm to 92.5 nm. Claim 5 In claim 1, the low-emission glass having a thickness of 28 nm to 32 nm of the fourth dielectric layer. Claim 6 The low-emissivity glass according to claim 1, wherein the first infrared reflective layer and the second infrared reflective layer comprise one or more selected from the group consisting of Ag, Cu, Au, Al, and Pt. Claim 7 A low-emissivity glass according to claim 1, wherein the first to fourth dielectric layers each independently comprise one or more nitrides or oxides selected from the group consisting of Zn, Ti, Si, Nb, Sn, Al, Zr, and Ta. Claim 8 In claim 7, the first to fourth dielectric layers comprise silicon-aluminum nitride or silicon-zirconium nitride, a low-emission glass. Claim 9 In claim 1, the low-emissivity glass has an emissivity of 0.005 or less as measured according to KS L 2525, and has an a* value of 0 to -3 and a b* value of -3 to -11 in CIE lab color coordinates. Claim 10 In claim 1, the low-emissivity glass has a transmittance of 20% to 50% at a wavelength of 380 to 780 nm as measured according to KS L 2514, an external reflectance of 10% to 20% at a wavelength of 380 to 780 nm as measured according to KS L 2514, and an internal reflectance of 40% or less at a wavelength of 380 to 780 nm as measured according to KS L 2514.

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