WO2018199431A1

WO2018199431A1 - Curved glass and manufacturing method thereof

Info

Publication number: WO2018199431A1
Application number: PCT/KR2018/000789
Authority: WO
Inventors: 문병천; 최학년; 안정식; 이진수; 장봉철; 황민규
Original assignee: 엘지전자 주식회사
Priority date: 2017-04-24
Filing date: 2018-01-17
Publication date: 2018-11-01

Abstract

The present invention relates to curved cover glass used for a curved display, and a manufacturing method thereof. The present invention provides tempered glass comprising: glass including a curved area; and a low reflection coating layer, coated on a surface of the glass, composed of a mixture of a binder and a hollow material, wherein the glass comprises potassium ions which penetrate up to a predetermined depth therein. According to the present invention, a low reflection coating layer is formed prior to curved surface processing, and thus, the low reflection coating layer can be uniformly formed even on areas having different curvatures. Thus, the present invention can minimize the color difference generated in curved glass due to low reflection coating layers.

Description

Curved glass and its manufacturing method

The present invention relates to a curved cover glass used in a curved display and a manufacturing method thereof.

In a conventional display, a cover glass for protecting the display is disposed. The cover glass should be high in light transmittance and not easily broken. To this end, various reinforcement methods have been utilized to prevent the glass from breaking easily.

Meanwhile, as display technology develops, curved displays have started to develop, and accordingly, demand for curved cover glass is increasing. In particular, attempts have been made to apply the curved display to a vehicle.

As an example of the glass strengthening method, a chemical strengthening method has been utilized. Conventional cover glass was prepared by replacing sodium ions contained in the glass with potassium ions through an ion exchange method. When the glass is cooled in a state in which potassium ions are relatively bulkier than sodium ions, the volume of the glass can be increased while maintaining the same volume as before.

The chemical strengthening method is a very useful glass strengthening method because it does not increase the thickness of the glass, and does not lower the transparency of the glass. However, the chemical strengthening method has some disadvantages.

First, when the chemically strengthened glass is exposed to high temperatures, the chemical strengthening effect disappears. For this reason, there is a problem that high temperature processing cannot be performed after chemically strengthening the glass. Second, since the chemical strengthening proceeds in a manner of penetrating potassium ions into the glass, there is a problem that the chemical strengthening cannot be performed after the coating layer is formed on the glass. Due to this drawback, the chemical strengthening must be carried out after the curved surface processing, and the coating layer must be formed after the chemical strengthening.

Meanwhile, in order to apply the curved glass to a vehicle or the like, a low reflection coating layer is used that does not interfere with the driver's view. The low reflection coating layer absorbs light introduced from the outside, thereby preventing the cover glass from reflecting light and obstructing the driver's view.

Since the low reflection coating layer may be destroyed at high temperatures and may interfere with chemical strengthening, it should be formed after the surface processing and chemical strengthening. However, when the coating layer is formed on the curved region, the thickness of the coating layer may vary depending on the curvature of the curved region. In addition, when the coating layer is formed in the curved region, the uniformity of the coating layer may be inferior as compared with forming the coating layer in the planar region. As a result, color differences between the planar region and the curved region may occur. This can give a sense of heterogeneity to the user.

The present invention provides a curved glass and a method of manufacturing the same that can solve the problems caused when chemically strengthening the curved glass while forming a low reflection coating layer.

First, it is an object of the present invention to provide a tempered glass and a manufacturing method thereof comprising a curved surface where the low reflection coating layer is uniformly formed in the curved area.

Secondly, an object of the present invention is to provide a tempered glass including a curved surface for minimizing color difference between regions having different curvatures, and a method of manufacturing the same.

In addition, the present invention aims to be able to form a coating layer irrespective of the glass area by converting the low reflection coating treatment to a coating method instead of dry deposition.

In order to achieve the first object described above, the present invention comprises a glass comprising a curved area, a low reflection coating layer coated on the glass surface, a low reflection coating layer consisting of a mixture of a binder and a hollow material, the glass to a predetermined depth Provided is a tempered glass, characterized in that the ions have penetrated.

In one embodiment, the content of the hollow material included in the low reflection coating layer, the central portion of the low reflection coating layer may be higher than the edge of the low reflection coating layer.

In one embodiment, the binder may be in a state in which Tetraethyl orthosilicate and Trimethoxy-methylsilane are polymerized together.

In one embodiment, the glass may include a first region having a first curvature and a second region having a second curvature different from the first curvature.

In an embodiment, the color difference ΔE * ab between the first area and the second area may be 2 or less based on the first area.

In one embodiment, based on the thickness of the low reflection coating layer coated on the first region, the thickness of the low reflection coating layer coated on the first region and the thickness of the low reflection coating layer coated on the second region is 10% It can be different.

In one embodiment, the weight average molecular weight of the binder may be 1500 to 3500.

In one embodiment, the average particle diameter of the hollow material may be 60 to 90nm.

In one embodiment, the low reflection coating layer may be formed of a single layer.

In one embodiment, the depth of penetration of the potassium ions may be 30 to 50μm.

In one embodiment, the thickness of the low reflection coating layer may be 100 to 150 nm.

In addition, the present invention is a step of polymerizing the first monomer and the second monomer to form a binder polymer, by mixing the binder polymer and the hollow material and then polymerizing, to prepare a low reflection coating liquid, the low reflection coating liquid flat glass Forming a low reflection coating layer by baking on the glass, and forming a low reflection coating layer on the flat glass on which the low reflection coating layer is formed. It provides a method for producing tempered glass comprising the step of penetrating potassium ions.

According to the present invention, since the low reflection coating layer is formed before the curved surface processing, the low reflection coating layer can be uniformly formed even in regions having different curvatures. Through this, the present invention can minimize the color difference generated in the curved glass due to the low reflection coating layer.

Further, according to the present invention, since the low reflection coating layer does not interfere with chemical strengthening, the low reflection coating layer can be formed on the glass surface before chemical strengthening. Through this, the present invention can form a low reflection coating layer before the glass is curved, it is possible to increase the uniformity of the low reflection coating layer.

1 is a conceptual diagram illustrating a conventional method of performing chemical strengthening and low reflection coating on curved glass.

2 is a conceptual diagram illustrating a method of manufacturing tempered glass according to the present invention.

3 is a conceptual diagram showing a cross section of the tempered glass according to the present invention.

Figure 4a is a cross-sectional picture of the tempered glass before chemical strengthening.

Figure 4b is a cross-sectional picture of the tempered glass after chemical strengthening.

5 is a graph showing reflectances before and after chemical strengthening.

Figure 6a is a graph showing the element distribution of the tempered glass chemically strengthened in the absence of a coating layer.

6b is a graph showing an element distribution of tempered glass according to the present invention.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, and the same or similar components are denoted by the same reference numerals regardless of the reference numerals, and redundant description thereof will be omitted. In addition, in describing the embodiments disclosed herein, when it is determined that the detailed description of the related known technology may obscure the gist of the embodiments disclosed herein, the detailed description thereof will be omitted. In addition, the accompanying drawings are intended to facilitate understanding of the embodiments disclosed herein, but are not limited to the technical spirit disclosed herein by the accompanying drawings, all changes included in the spirit and scope of the present invention. It should be understood to include equivalents and substitutes.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this application, the terms "comprises" or "having" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

First, a conventional method of performing chemical strengthening on a curved glass and forming a low reflection coating layer will be described.

According to the conventional method, the step (S120) of processing the flat glass of the desired size (S110), and the flat surface of the flat glass 110 (S120) proceeds first. Curve forming is carried out at a high temperature of 600 ° C or higher. For this reason, when the chemical strengthening and the low reflection coating is performed before the surface forming, the chemical strengthening effect may disappear or the low reflection coating layer may be broken during the surface forming.

Thereafter, in the conventional method, step S130 of chemically strengthening the curved glass is performed. Chemical strengthening is a method of increasing the hardness of the glass by penetrating potassium ions into the glass, when the coating layer is formed on the glass surface, it is difficult to penetrate potassium ions. Because of this, chemical strengthening must be performed prior to forming a coating layer on the glass surface.

Finally, forming a low reflection coating layer on the surface of the chemically strengthened curved glass (S140). The deposition method is utilized to form a relatively uniform coating layer on the curved shape. However, even using such a deposition method, it is difficult to reduce the difference in thickness between the coating layer deposited on each of the planar region and the curved region below a certain level. As a result, the curved area has a different color from the planar area.

The present invention provides a method for uniformly forming a low reflection coating layer in performing chemical strengthening and low reflection coating on curved glass. Hereinafter, a method of manufacturing tempered glass according to the present invention will be described with reference to the accompanying drawings.

First, in the manufacturing method according to the present invention, the step S220 of processing a flat glass of a desired size and forming a low reflection coating layer on the flat glass is performed.

The low reflection coating layer 120 according to the present invention may be formed through a firing process after applying a coating liquid consisting of a mixture of a binder and a hollow material to the flat glass 110 surface.

Here, the hollow material serves to lower the reflectance of the coating layer. Specifically, the hollow material lowers the reflectance by making an air layer on the glass surface to lower the refractive index.

On the other hand, the hollow material may be made of silica. Since the hollow silica made of silica does not decompose even at a high temperature of 600 ° C. or higher, the coating layer may not be broken even if the low reflection coating layer is formed and then the curved surface is formed.

On the other hand, the average particle diameter of the hollow material may be 60 to 90nm. Hollow silica having a particle diameter of less than 60 nm is difficult to manufacture in fact, and when the particle diameter of the hollow silica exceeds 90 nm, the coating layer is difficult to form uniformly because it becomes similar to the thickness of the coating layer to be described later.

On the other hand, the binder serves to allow the hollow material to be fixed to the glass. Since the binder is exposed to a high temperature of 600 ° C. or higher during curved forming, the binder should be made of a material that does not break down even at a temperature of 600 ° C. or higher. For example, the binder may be made of a silane-based binder, and specifically, the binder may be a binder of tetraethyl orthosilicate (TEOS), trimethoxy-methylsilane (MTMS), Fluoro-Silaner series, Acryl-Silane series, Silazane series have.

On the other hand, the weight average molecular weight of the binder may be 1500 to 3500. When the weight average molecular weight of the binder is less than 1500, since the viscosity of the coating liquid is lowered, the influence on foreign matters during coating may be increased, and the intermolecular interaction may be weakened, thereby decreasing the coatability. On the other hand, when the weight average molecular weight of the binder exceeds 3500, the viscosity is high, the smoothness of the coating layer is lowered, the stability of the coating layer may be lowered.

Meanwhile, in the present invention, two or more kinds of binders may be mixed and used. For example, a mixture of TEOS and MTMS can be utilized as the binder. In this case, the monomers of each of TEOS and MTMS may be mixed and polymerized first, and then mixed with a hollow material to prepare a coating solution. When TEOS and MTMS are first polymerized and then mixed with the hollow material, the binder molecules surround the hollow material surface. As a result, a core-cell structure can be formed in which the hollow material is the core and the binder molecules are the cell. This core-cell structure allows the hollow material to spread evenly when applied to the glass surface. In addition, since the binder always surrounds the hollow material, the content of the binder is increased at the edge of the low reflection coating layer, and the content of the hollow material is more at the center of the low reflection coating layer. Through this, the present invention can protect the hollow material having a function of substantially lowering the reflectance from external impact or the like.

After applying a coating liquid consisting of a mixture of a hollow material and a binder to the flat glass surface, a low reflection coating layer may be formed through a firing process. Here, the firing may be performed for 4 to 6 minutes at a temperature of 400 to 750 ℃ in the kiln.

The low reflection coating layer formed in the above-described manner may have a thickness of 100 to 150 nm. If the thickness of the coating layer is less than 100nm, the effect of reducing the reflectance is inferior, and if it exceeds 150nm, the coating layer is inferior in uniformity, and the chemical strengthening to be performed later may not be performed properly.

On the other hand, the low reflection coating layer may be composed of a single layer so that potassium ions can pass through the coating layer.

On the other hand, the porosity of the low reflection coating layer according to the present invention may be 30 to 70%. When the porosity of the low reflection coating layer is less than 30%, it is difficult to expect the reflection suppression effect, and potassium ions hardly penetrate to the glass surface during chemical strengthening, which will be described later. On the other hand, when the porosity of the coating layer exceeds 70%, the durability of the coating layer may be excessively degraded.

On the other hand, the low reflection coating layer formed in the above-described manner has a reflectance of 1% or less.

On the other hand, after forming the low reflection coating layer on the flat glass, the step of forming the curved surface of the flat glass (S230) is performed. Curved molding may be performed by press molding, and may be performed at a pressure of 0.005 to 0.006 MPa at a temperature of 700 to 780 ° C. However, the present invention is not limited thereto.

Since the hollow material and the binder according to the present invention are not decomposed at a temperature of 700 to 780 ° C., the low reflection coating layer is not destroyed even after the curved surface forming, and the uniform coating layer formed on the flat glass can be maintained as it is.

On the other hand, the radius of curvature of the curved glass may be 5R or more. However, the present invention is not limited thereto, and the radius of curvature may vary depending on the thickness of the glass and the area of the glass.

Finally, step S240 is performed to chemically strengthen the curved surface.

Chemical strengthening may be carried out by immersing the glass in KNO 3 solution heated to a temperature of 380 to 435 ° C. for 2 to 8 hours. At this time, due to the difference in potassium ion concentration between the glass and the solution, potassium ions penetrate into the glass. As a result, the glass strength is improved.

Conventional chemical strengthening is carried out to allow potassium ions to penetrate 30 μm or more into the glass. In this case, the glass is implemented with a CS of 750 MPa or more. Since the low reflection coating layer according to the present invention is formed to a thickness of less than 150nm and has a porosity of 30% or more, potassium ions can easily penetrate the glass surface. That is, the low reflection coating layer according to the present invention does not interfere with the movement of potassium ions. An experimental example thereof will be described later.

On the other hand, because the chemical strengthening is carried out in a high pH solution, hydrolysis may destroy the low reflection coating layer, especially hollow material. If TEOS and MTMS utilize primarily polymerized binders, the binder can surround the hollow material surface and protect the hollow material from strongly basic solutions.

Hereinafter, the tempered glass manufactured by the method mentioned above is demonstrated.

The tempered glass 100 manufactured by the above-described manufacturing method includes a glass 110 including a curved area, a low reflection coating layer coated on the glass surface and made of a mixture of a binder 120 and a hollow material 130. The glass is characterized in that potassium ions penetrate to a predetermined depth.

On the other hand, when using a binder polymerized primarily by TEOS and MTMS in the tempered glass manufacturing process, the content of the hollow material included in the low reflection coating layer, the center of the low reflection coating layer is higher than the edge of the low reflection coating layer . This structure protects the hollow material from strongly basic solutions and protects the hollow material from external impacts upon chemical strengthening.

On the other hand, the tempered glass may include curved surfaces having different curvatures according to its use. For example, the glass may include a first region having a first curvature and a second region having a second curvature different from the first curvature. Here, when the curvature is 0, the curvature may be referred to as a plane, and the glass according to the present invention may include a planar region.

Meanwhile, since the tempered glass according to the present invention is formed by forming a coating layer on the flat glass and then curved, the thickness of the low reflection coating layer coated on the first region is based on the thickness of the low reflection coating layer coated on the first region. The thickness of the low reflection coating layer coated on the second region may vary within 10%.

For this reason, in the tempered glass according to the present invention, the color difference ΔE * ab between the first region and the second region may be 2 or less based on the first region. The greater the difference in curvature between the two regions of the glass, the larger the color difference. In the tempered glass according to the present invention, the color difference ΔE * ab between a region having a maximum curvature and a region having a minimum curvature is 2 or less. That is, in the tempered glass according to the present invention, the color difference between all arbitrary regions is 2 or less.

On the other hand, the radius of curvature of the curved glass may be 5R or more. However, the present invention is not limited thereto, and the radius of curvature may vary depending on the thickness of the glass and the area of the glass. That is, the tempered glass according to the present invention may have a curvature of at most 1 / 5R. Accordingly, the maximum curvature difference in the tempered glass according to the present invention may be 1 / 5R. In the tempered glass according to the present invention, the color difference ΔE * ab between two regions where the difference in curvature is maximum is 2 or less.

On the other hand, in the tempered glass according to the present invention, the depth of penetration of potassium ions into the glass may be 30 to 50 μm. This is the same depth as the potassium ions penetrated when the chemical strengthening is performed in the absence of the coating layer. That is, according to the present invention, even if the chemical strengthening after the coating layer is formed, the same chemical strengthening effect as in the prior art can be obtained.

Hereinafter, the present invention will be described in more detail with reference to examples and experimental examples, but the scope and contents of the present invention are not reduced or limited by the following examples and experimental examples.

Example. Manufacture of Tempered Glass

Tempered glass was manufactured according to the above-mentioned manufacturing method using hollow silica having an average particle diameter of 73.29 nm and a dispersion degree of 0.031 as a hollow material, and a material obtained by primarily polymerizing TEOS and MTMS as a binder.

Figure 4a is a cross-sectional picture of the tempered glass before chemical strengthening, Figure 4b is a cross-sectional picture of the tempered glass after chemical strengthening.

In the case of Figure 4b, it can be seen that the wave pattern is generated in the glass, but this is only a pattern generated during the glass cutting process, even if the chemical strengthening does not change the structure of the glass with the naked eye.

Meanwhile, referring to FIGS. 4A and 4B, it can be seen that the binder forms a coating layer in a state surrounding the surface of the hollow material. Accordingly, a binder is mainly disposed at the edge of the coating layer, and a hollow material is mainly disposed at the center of the coating layer.

On the other hand, referring to Figure 4b it can be seen that the low reflection coating layer is 100 to 130nm.

Experimental Example 1. Reflectance Measurement of Tempered Glass

When manufacturing the tempered glass according to the embodiment, the reflectance was measured before and after chemical strengthening.

5 is a graph showing reflectances before and after chemical strengthening.

Referring to Figure 5, after the chemical strengthening it can be seen that the reflectance of the tempered glass slightly decreased. That is, even when chemical strengthening is performed, it can be seen that the hollow material included in the low reflection coating layer is not destroyed.

On the other hand, referring to Figure 5, the tempered glass according to the present invention can be confirmed that the reflectance is less than 1% at a wavelength of 500nm or more. That is, it can be confirmed that the tempered glass according to the present invention has a reflectance of less than 1% even at a thickness of 100 to 150 nm.

Experimental Example 2 Color difference measurement of tempered glass

ΔE * ab was 0.8 as a result of measuring the color difference between the curved area and the planar area of the tempered glass according to the present invention. This is difficult for the human eye to distinguish. Through this, the tempered glass according to the present invention is almost no color difference caused by the low reflection coating does not give a user a foreign object.

On the other hand, for comparison, the color difference between the curved area and the planar area of the curved glass on which the low reflection coating layer was formed by the conventional deposition method was measured. As a result, ΔE * ab was 8, the color of the planar region was purple, and the color of the curved region was yellow. This is the color difference that humans see with the naked eye.

Experimental Example 3 Chemical Strengthening Depth Measurement

Element (Na, Si, K) distribution according to the depth of the tempered glass prepared in Example was measured. On the other hand, for comparison, the element distribution of the tempered glass which was chemically strengthened in the absence of the coating layer was measured.

6A is a graph showing an element distribution of tempered glass subjected to chemical strengthening in the absence of a coating layer, and FIG. 6B is a graph showing an element distribution of tempered glass according to the present invention.

6a and 6b, it can be seen that the distribution of the K element according to the depth of each of the tempered glass and the tempered glass according to the present invention performed the chemical strengthening in the absence of the coating layer. Through this, it can be seen that the chemical strengthening effect similar to the conventional one can be obtained even if the chemical strengthening by the manufacturing method according to the present invention.

It is apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential features of the present invention.

In addition, the above detailed description should not be interpreted as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

Claims

A glass comprising a curved area;

A low reflection coating layer coated on the glass surface, the mixture comprising a binder and a hollow material;

The glass,

Tempered glass, characterized in that the potassium ion has penetrated to a predetermined depth.
The method of claim 1,

The content of the hollow material included in the low reflection coating layer,

Tempered glass, characterized in that the central portion of the low reflection coating layer is higher than the edge of the low reflection coating layer.
The method of claim 2,

The binder is tempered glass, characterized in that the tetraethyl orthosilicate and Trimethoxy-methylsilane is polymerized together.
The method of claim 1,

The glass,

A first region having a first curvature; And

And a second region having a second curvature different from the first curvature.
The method of claim 4, wherein

The tempered glass according to the first region, wherein the color difference ΔE * ab between the first region and the second region is 2 or less.
The method of claim 4, wherein

Based on the thickness of the low reflection coating layer coated on the first region,

Tempered glass, characterized in that the thickness of the low reflection coating layer coated on the first region and the thickness of the low reflection coating layer coated on the second region within 10%.
The method of claim 1,

Tempered glass, characterized in that the weight average molecular weight of the binder is 1500 to 3500.
The method of claim 1,

Tempered glass, characterized in that the average particle diameter of the hollow material is 60 to 90nm.
The method of claim 1,

The low reflection coating layer is tempered glass, characterized in that consisting of a single layer.
The method of claim 1,

Tempered glass, characterized in that the penetration depth of the potassium ion is 30 to 50um.
The method of claim 1,

The thickness of the low reflection coating layer,

Tempered glass, characterized in that 100 to 150 nm.
Polymerizing the first monomer and the second monomer to form a binder polymer;

Mixing and then polymerizing the binder polymer and the hollow material to prepare a low reflection coating solution;

Coating the low reflection coating liquid on a flat glass and then baking to form a low reflection coating layer;

Molding the flat glass on which the low reflection coating layer is formed at a predetermined temperature such that a curved surface is formed on the flat glass on which the low reflection coating layer is formed; And

Method of manufacturing a tempered glass comprising the step of penetrating potassium ions into the glass comprising a curved surface.