KR20180045500A - Anti-reflective construction glass - Google Patents

Abstract

Anti-reflective construction glass using a two-layer thin film is disclosed. The anti-reflective construction glass according to the present invention comprises: a glass substrate; and an anti-reflective layer disposed on the glass substrate, wherein the anti-reflective layer has a two-layer structure composed of a first layer disposed on the glass substrate and a second layer disposed on the first layer, wherein the refractive index of the first layer is higher than the refractive index of the second layer, and the thickness of the first layer is thinner than the thickness of the second layer.

Description

ANTI-REFLECTIVE CONSTRUCTION GLASS

The present invention relates to an antireflection glass for architectural use, and more particularly to an antireflection glass for architectural use using a two-layer thin film.

In many modern buildings, a large area of the exterior is made of glass to improve aesthetics. In the case of a glass enclosure, light is reflected from the glass, causing glare around it. To solve this problem, anti-reflective coating is applied to glass for construction. The anti-reflective coating is performed by coating the glass with a multilayered film in which a high refractive index material and a low refractive index material are repeated.

However, in the glass coated with the multilayer thin film, the refractive index of the thin film of each layer increases according to the temperature during the heat treatment process, which may decrease the transmittance and degrade the antireflective function.

Therefore, nonreflective glass having a reflectance close to 0% is required.

As a background related to the present invention, there is disclosed a low refractive index thin film manufacturing method disclosed in Korean Patent Laid-Open Publication No. 10-2007-0016579 (published on Mar. 2, 2007) and an anti-reflective coating method using the same.

An object of the present invention is to provide an antireflection glass for construction having a two-layer thin film structure and having an anti-reflection effect.

According to an aspect of the present invention, there is provided an antireflection glass for architectural use, comprising a glass substrate and an antireflective layer disposed on the glass substrate, wherein the antireflective layer comprises a first layer disposed on a glass substrate, Wherein the refractive index of the first layer is higher than the refractive index of the second layer and the thickness of the first layer is thinner than the thickness of the second layer .

The first layer may be made of a metal material and the second layer may be made of a ceramic material.

The metal may include at least one of gold (Au), silver (Ag), copper (Cu), and aluminum (Al).

The thickness of the first layer may be less than 20 nm, and the thickness of the second layer may be 20 to 100 nm.

The thickness of the first layer and the thickness of the second layer may satisfy the following expression (1).

[Formula 1]

Y _inc : admittance of incident medium (air)

Y _eq : the alternate admittance from the glass substrate to the first layer;

Y ₂ : admittance of the second layer

d ₂ : thickness of the second layer

The antireflection glass for architectural use according to the present invention is composed of a two-layer thin film, which is more stable than the conventional multilayer thin film. Further, a thin film having an appropriate thickness is provided by the reflectance formula, and an anti-reflection effect with a reflectance close to 0% can be provided.

1 is a cross-sectional view of an antireflection glass for construction according to the present invention.
2 is a graph showing the reflectance according to wavelengths according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an antireflection glass for construction according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In conventional architectural glass, an anti-reflective coating is used to mix two or more kinds of materials so that the refractive index continuously changes. Glass is mainly coated with a multilayer thin film. Architectural glass coated with multilayer thin film not only improves the heat insulation and soundproof effect of the building but also is used in a wide area of the exterior of the building, and has a effect of producing aesthetic appearance gorgeously and beautifully.

However, in the glass coated with the multilayer thin film, the thin film refractive index of each layer increases with the temperature during the heat treatment process, thereby decreasing the transmittance and deteriorating the anti-reflection function.

The construction glass of the present invention is composed of a two-layer thin film and exhibits an anti-reflection effect with a reflectance close to 0%. In addition, the reflectance formula is used to provide the appropriate thickness of the thin film.

1 is a cross-sectional view of an antireflection glass for construction according to the present invention.

Referring to FIG. 1, an antireflection glass for architectural use according to the present invention includes a glass substrate and an antireflection layer disposed on the glass substrate.

A glass substrate having a transmittance of 80% or more and a small absorption coefficient may be used for satisfying light transmittance, and a glass substrate having a refractive index of approximately 1.3 to 1.5 may be used. Examples thereof include borosilicate glass including B ₂ O ₃ and soda lime glass based on Na ₂ O-CaO-SiO ₂ .

In order to reduce the difference in refractive index between the organic substrate and the first layer to lower the reflectance, it is preferable that the glass substrate has a refractive index difference of 0.1 or more with respect to the refractive index of the first layer.

The antireflection layer has a two-layer structure composed of a first layer disposed on a glass substrate and a second layer disposed on the first layer. The first layer may be a metal material including at least one of gold (Au), silver (Ag), copper (Cu), and aluminum (Al). The second layer is made of a ceramic material such as SiO ₂ , Al ₂ O ₃ , Y ₂ O ₃ or the like, and generally used SiO ₂ can be applied to the second layer.

The refractive index of the first layer is preferably higher than the refractive index of the second layer and the refractive index of the second layer is higher than the refractive index of the first layer. In order to reduce the reflectance by reducing the refractive index difference between the first layer and the second layer, And a refractive index difference of 0.1 or more.

More specifically, the refractive index of the first layer may be approximately 1.3 to 1.5, and the refractive index of the second layer may be approximately 1.0 to 1.3. When the refractive index of the second layer is lower than the refractive index of the first layer, the refractive index difference between the first layer and the second layer is reduced and the reflectance is lowered. Thus, a thin film having a reflectance close to 0% can be provided.

If the refractive indexes of the first layer and the second layer are similar or the refractive index of the first layer is lower than the refractive index of the second layer, the transmittance decreases and reflectance increases.

According to the reflectance formula, when the optical admittance of the incident medium coincides with the substitutive admittance of the optical element, the reflectance becomes 0%.

When the two-layer thin film as shown in Fig. 1 is applied to the following formula 1, it can be concluded that the reflectance becomes 0%.

In order to exhibit the anti-reflective effect of the thin film, it is preferable that the thickness of the first layer is thinner than the thickness of the second layer. More specifically, the thickness of the first layer may be less than 20 nm, and the thickness of the second layer may be 20 to 100 nm. If the thickness of the first layer exceeds 20 nm or is thicker than the thickness of the second layer, there is a problem that the amount of absorption of light increases excessively.

The thickness (d ₁ ) of the first layer and the thickness (d ₂ ) of the second layer of the present invention can satisfy the following formula (1).

[Formula 1]

Y _inc : admittance of incident medium (air)

Y _eq : the alternate admittance from the glass substrate to the first layer;

Y ₂ : admittance of the second layer

d ₂ : thickness of the second layer

Since the left and right sides of Equation 1 always exist in the form of complex number (i), the real number / imaginary number of the right side = real number / imaginary number of the left side. That is, the ratio of the real numbers and the imaginary numbers on the left and right sides should be the same.

Y _eq is a parameter depending on d ₁ and is a refractive index from the glass substrate to the first layer, And Y ₂ is the refractive index of the second layer. K ₀ is a phase constant (wavelength constant), K ₀ = 2π / wavelength length (nm) of the visible light region, and the actual parameters in the equation 1 are d ₁ and d ₂ .

[Table 1]

For example, by applying the values in Table 1 to Equation 1, a value of d ₁ that can derive Y _eq can be obtained, and d ₂ of the right side can be obtained from the left side of the completed value.

As shown in Table 1, the d ₂ value can be obtained using a glass substrate made of soda lime, a first layer made of Al metal and having a thickness of 1.4 nm, and a second layer made of SiO ₂ .

First, the ^{tan -1 {1- (1.63-1.28i) /} i (1.46- (1.63-1.28i) /1.46)} = 0.01232Х1.46Хd 2 expression, tan ^-1 {0.989722-0.90075i} = 0.01799Хd ₂ Lt; / RTI > Calculating from the value of 1.025 on the left, we can calculate the result with d ₂ = 57 nm.

Therefore, the thickness d ₁ of the first layer and the thickness d ₂ of the second layer, which have an anti-reflection effect with a reflectance close to 0%, can be calculated.

2 is a graph showing the reflectance according to wavelengths according to the present invention.

Referring to FIG. 2, it is shown that the average reflectance is about 0 to 1% in the visible light wavelength range from 700 nm (red) to 400 nm (purple). In particular, the average reflectance of the thin film is the closest to 0% in the wavelength range of about 500 nm to 520 nm. This result means that the reference wavelength applied to the K ₀ wavenum in Equation 1 is 510 nm. In the same manner, when the reference wavelength is set to 400 nm and the calculation result is derived from the formula 1, the reflectance of the thin film becomes close to 0% in the 400 nm region. When the reference wavelength is set to 600 nm and the calculation result is derived from the formula 1, the reflectance of the thin film becomes close to 0% in the region of 600 nm.

As described above, in the present invention, the reflection color of the thin film can be adjusted by adjusting the reference wavelength nearest to 0% reflectance. The reflection color means a wavelength at which a relatively large amount of reflection occurs.

The thickness of the first layer and the second layer can be uniformly formed by uniformly dispersing the particles on the glass substrate. For example, metal particles and ceramic particles can be deposited by rotating the substrate, but are not limited thereto.

As described above, the antireflection layer having a two-layer structure is formed on a glass substrate of the antireflection glass for construction according to the present invention, so that it is relatively easy to produce the antireflection glass in comparison with a glass having a thin film of the conventional multilayer structure. In addition, the thicknesses of the first layer and the second layer thin film exhibiting the anti-reflection effect can be set by the equation (1) derived from the reflectance formula.

While the present 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, It is to be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

d ₁ : thickness of the first layer
d ₂ : thickness of the second layer

Claims (5)

A glass substrate and an antireflection layer disposed on the glass substrate,
Wherein the antireflection layer has a two-layer structure including a first layer disposed on a glass substrate and a second layer disposed on the first layer, wherein the refractive index of the first layer is higher than the refractive index of the second layer, Wherein the thickness of the first layer is thinner than the thickness of the second layer.
The method according to claim 1,
Wherein the first layer is made of a metal material and the second layer is made of a ceramic material.
3. The method of claim 2,
Wherein the metal comprises at least one of gold (Au), silver (Ag), copper (Cu), and aluminum (Al).
The method according to claim 1,
Wherein the thickness of the first layer is less than 20 nm and the thickness of the second layer is 20 to 100 nm.
The method according to claim 1,
Wherein the thickness of the first layer and the thickness of the second layer satisfy the following expression (1).
[Formula 1]

Y _inc : admittance of incident medium (air)
Y _eq : the alternate admittance from the glass substrate to the first layer;
Y ₂ : admittance of the second layer
d ₂ : thickness of the second layer

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