KR102521878B1 - Curved Tempered Glass And Method For Manufacturing The Same - Google Patents

Abstract

The present invention relates to a tempered glass comprising a glass substrate having a stress layer formed on its surface after being strengthened, and a method for manufacturing the same, wherein the glass substrate extends and bends in at least one direction from the flat portion and the flat portion, and has a thickness different from that of the flat portion. Includes a curved portion having. An inclination between one surface of the flat part and one surface of the curved part adjacent to the one surface of the flat part gradually changes.

Description

Tempered glass having a curved surface and manufacturing method thereof {Curved Tempered Glass And Method For Manufacturing The Same}

The present invention relates to a tempered glass having a curved portion and a manufacturing method thereof.

Recently, in order to increase the mechanical strength of fragile glass, tempered glass, the surface of which is tempered, is being spread, and its application fields are also diversifying. For example, thanks to the development of portable information processing devices, demand for various displays is rapidly increasing. The display device includes a protective cover for protecting internal elements of the display device, and glass may be used as a material for the protective cover. When glass is used as a protective cover, it has the advantage of securing weather resistance, scratch resistance, and high transmittance, but has the disadvantage of being easily broken by impact or the like caused by external factors because it is exposed to the outside. In order to solve these disadvantages, research is being actively conducted to secure the mechanical strength of glass.

As a method for strengthening glass, a physical strengthening method is known. The physical strengthening method is a method of heating the glass to a high temperature for a certain period of time and then rapidly cooling the surface of the glass by air cooling to generate compressive stress on the surface of the glass and tensile stress on the inside.

However, the physical strengthening method using the temperature difference between the inside and the outside has limitations in strengthening thin film-type glass. That is, in the case of thin glass, since it is difficult to generate a temperature difference between the surface and the inside, it is difficult to form compressive stress on the surface of the glass sheet. The display device includes a touch screen panel capable of recognizing a user's touch and/or gesture, and can sense a user's hand or movement of a conductor. Glass protecting the display device is required to be formed as a thin film in order to increase touch sensing sensitivity. Accordingly, there is a limit to using a physical strengthening method to form a thin tempered glass.

On the other hand, as glass is applied in various fields, glass having a curved portion corresponding to various needs of users is spreading. For example, as a curved display device is provided, it is required to manufacture glass having a curved portion as a protective cover corresponding to the curved display device.

In the prior art for manufacturing glass including a curved portion, a machining method using a traditional lathe and an automatic lathe (CNC), a press 55 that heats the glass to a certain temperature or higher and then presses it using a mold corresponding to the glass shape including the curved portion. There are a molding method, and a slumping molding method using gravity and a mold at a high temperature. However, the glass provided by this method has problems of poor quality, low productivity and yield. In addition, it is also a problem how the tempered glass can be processed.

Therefore, there is a need to develop a method for manufacturing a tempered glass capable of processing a curved part while enhancing mechanical strength by tempering thin glass.

An object of the present invention is to provide a tempered glass having a curved portion by chemically strengthening thin glass and performing a removal process on a portion thereof. In addition, an object of the present invention is to provide a tempered glass in which a step that can be formed at the boundary between a flat portion and a curved portion is reduced.

In order to achieve the above or other objects, the present invention relates to a tempered glass comprising a glass substrate having a stress layer formed on a surface thereof after being strengthened, and extending and bending in at least one direction from the flat part, wherein the It includes a curved portion having a thickness different from that of the flat portion. An inclination between one surface of the flat part and one surface of the curved part adjacent to the one surface of the flat part gradually changes.

In the method for manufacturing tempered glass according to an embodiment of the present invention, a first step of preparing a glass substrate having a flat portion and a curved portion extending in at least one direction from the flat portion is defined; A second step of forming a stress layer on the surface, a third step of bending the curved part by performing a removal process on at least a part of the surface of the curved part, and a removal process along the boundary between the flat part and the curved part. and a fourth step of processing the formed step so that an inclination between one surface of the plane part and one surface of the curved part adjacent to the one surface of the plane part is gradually changed.

A method for manufacturing tempered glass according to another embodiment of the present invention includes a first step of preparing a glass substrate having a flat portion and a curved portion extending in at least one direction from the flat portion, and strengthening the glass substrate to obtain the glass substrate. A second step of forming a stress layer on a surface, and a third step of bending the curved part by performing a polishing process on at least a part of the surface of the curved part. An inclination between one surface of the flat part and one surface of the curved part adjacent to the one surface of the flat part gradually changes.

The tempered glass according to the present invention is tempered by a chemical strengthening method, so that the tempering process can be performed on a thin glass substrate, manufacturing cost and manufacturing time can be reduced, and productivity and yield can be improved. In addition, it has the advantage of being able to be strengthened without additional deformation or physical processing of the glass substrate.

Unlike conventional processing methods used to form a curved portion, the present invention forms a curved portion through an etching process, thereby improving productivity and yield, preventing deterioration in the quality of processed glass, and reducing manufacturing costs and manufacturing costs. It has the effect of reducing time. In addition, according to the tempered glass manufacturing method according to an embodiment of the present invention, since the designer can process the shape of the final product differently by adjusting the process conditions, various design changes are possible compared to the conventional processing method using a mold or the like. And it has the advantage of relatively easy design change.

According to the present invention, by reducing a step that may be formed along the boundary between a flat part and a curved part during a process, it is possible to prevent a step from being visually recognized from the outside. In addition, the present invention can prevent a problem of deterioration in visibility that may occur due to the accumulation of foreign substances on the stepped portion.

1 is a view showing a tempered glass according to a first embodiment of the present invention.
2 to 6 are cross-sectional views illustrating a process for manufacturing a tempered glass according to an embodiment of the present invention.
FIG. 7 is an enlarged view of an AR area in FIG. 6 .
8 to 12 are cross-sectional views illustrating a process for manufacturing a tempered glass according to another embodiment of the present invention.
13 is a view showing a tempered glass according to a second embodiment of the present invention.
14 is a cross-sectional view illustrating a tempered glass and a process for manufacturing the tempered glass according to an embodiment of the present invention.
15 is a cross-sectional view illustrating a tempered glass and a process for manufacturing the tempered glass according to another embodiment of the present invention.
16 to 19 are cross-sectional views illustrating a process for manufacturing a tempered glass according to another embodiment of the present invention.
FIG. 20 is an enlarged view of an area AR' in FIG. 19 .
21 relates to a third embodiment of the present invention, and is a view for explaining application fields of tempered glass according to the first and second embodiments.
22 is a flow chart explaining a process for manufacturing a tempered glass according to a fourth embodiment of the present invention.

Hereinafter, the embodiments disclosed in this specification will be described in detail with reference to the accompanying drawings, but the same or similar elements are given the same reference numerals regardless of reference numerals, and redundant description thereof will be omitted. The suffix "part" for components used in the following description is given or used interchangeably in consideration of ease of writing the specification, and does not itself have a meaning or role distinct from each other. In addition, in describing the embodiments disclosed in this specification, if it is determined that a detailed description of a related known technology may obscure the gist of the embodiment disclosed in this specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in this specification, the technical idea disclosed in this specification is not limited by the accompanying drawings, and all changes included in the spirit and technical scope of the present invention , it should be understood to include equivalents or 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. These terms are only used for the purpose of distinguishing one component from another.

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

In this application, terms such as "comprise" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

<First Embodiment>

Hereinafter, a tempered glass and a manufacturing method thereof according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 6 .

1 is a view showing a tempered glass according to a first embodiment of the present invention.

Referring to FIG. 1 , the tempered glass 1 according to the first embodiment of the present invention includes a flat portion FA and a curved portion BA. The flat portion FA means a region having a planar shape in the tempered glass 1 according to the present invention. The curved portion BA refers to a region having a curved shape by bending the tempered glass 1 according to the present invention. The curved portion BA is provided extending from at least one side of the flat portion FA. The flat portion FA has a first thickness t1, and the curved portion BA has a second thickness t2. At the boundary between the flat portion FA and the curved portion BA, a step 30 is formed due to a difference in thickness between the flat portion FA and the curved portion BA.

A method of manufacturing the tempered glass 1 according to an embodiment of the present invention will be described with reference to FIGS. 2 to 6 . 2 to 6 are cross-sectional views illustrating a process for manufacturing a tempered glass according to an embodiment of the present invention.

Referring to FIG. 2 , a glass substrate 10 for strengthening treatment is provided. A flat portion FA and a curved portion BA extending from at least one side of the flat portion FA are defined in the glass substrate 10 . The flat part FA means a region having a planar shape after passing through a final process. The curved portion BA means a region having a curved shape that is bent after passing through a final process.

Referring to FIG. 3 , a strengthening process of strengthening the glass substrate 10 in which the flat portion FA and the curved portion BA are defined is performed. The strengthening process proceeds according to the chemical strengthening method. The chemical strengthening method is a method of forming a stress layer on a glass surface layer through ion substitution. The stress layer may be the compressive stress layer 20 . The driving force for ion replacement can be governed by the diffusion coefficient of individual ions with concentration gradient diffusion. For example, by immersing the glass substrate 10 in a salt bath (molten potassium nitrate) at 400 to 500 ° C. for a certain period of time, alkali metal ions (sodium ions) having a small ionic radius present in the surface layer of the glass substrate 10 can be induced to be substituted with an alkali metal ion (potassium ion) having a relatively large ionic radius. Accordingly, the compressive stress layer 20 is formed on the surface of the glass substrate 10 . The compressive stress layer 20 refers to an outer surface layer of the glass substrate 10 formed when relatively large ions invade the surface of the glass substrate 10 by ion exchange. As the compressive stress layer 20 is formed, the strength of the glass substrate 10 vulnerable to tensile stress may be increased. The strength of the glass substrate 10 can be further improved as the depth of the compressive stress layer 20 (Depth Of Layer, hereinafter referred to as 'DOL') (D) is deep.

The tempered glass 1 according to an embodiment of the present invention is strengthened by a chemical strengthening method rather than a physical strengthening method, so that the thin glass substrate 10 can be strengthened, and manufacturing cost and manufacturing time can be reduced. Productivity and yield can be improved. In addition, it has the advantage of being able to be strengthened without additional deformation or physical processing of the glass substrate 10 .

Referring to FIG. 4 , a mask 50 is provided on the tempered glass substrate 10 . The mask 50 includes an opening OR and a non-opening NOR. The mask 50 may be made of a material that is not deformed by the etchant 60 . The mask 50 surrounds the entire surface along the circumference of the tempered glass substrate 10 and exposes one of the upper and lower surfaces of the curved portion BA through the opening OR. A surface of the curved portion BA exposed through the opening OR may be determined according to a bending direction intended by a designer. In other words, the bending direction of the curved portion BA may be determined according to the location of the opening OR. The location of the opening may determine the bending direction. For example, in order to bend the curved portion BA downward, the designer may arrange the opening OR of the mask 50 to expose the lower surface of the curved portion BA. Hereinafter, a case in which the openings OR are disposed to expose the lower surface in order to bend the curved portion BA downward will be described as an example.

Referring to FIG. 5 , an etching process of applying an etchant 60 to the surface of the glass substrate 10 provided with the mask 50 is performed. The etching process may include all known processes capable of removing the surface of the glass substrate 10 . The etchant 60 is preferably applied in a direction perpendicular to the surface exposed by the openings OR. Through the etching process, a portion of the thickness of the curved portion BA exposed to the outside by the opening OR is removed.

Referring to FIG. 6 , when the lower surface of the curved portion BA is removed by an etching process, a difference in DOL (D) occurs between the lower surface where the etching process is performed and the upper surface where the etching process is not performed. As the compressive stress formed on the lower surface of the curved portion BA is reduced compared to the compressive stress formed on the upper surface, the curved portion BA is bent downward in response to the difference in compressive stress. At this time, as the etching process is performed only on the curved portion BA, the thickness t2 of the curved portion BA is reduced compared to the thickness t1 of the flat portion FA. Accordingly, a step 30 is generated at the boundary between the curved portion BA and the flat portion FA.

Unlike the conventional processing methods used to form the curved portion BA, the present invention can improve productivity and yield by forming the curved portion BA through an etching process, and can prevent the quality deterioration of the processed glass. and has the effect of reducing manufacturing cost and manufacturing time. In addition, in the tempered glass manufacturing method according to an embodiment of the present invention, the designer adjusts the process conditions such as the tempering process time and the corresponding depth of the DOL, the type and amount of the etchant, and the etching process time, so that the shape of the final product is different. can be processed Therefore, compared to the conventional processing method using a mold or the like, various design changes are possible, and the design change is relatively easy.

For example, in the method of manufacturing the tempered glass 1 according to an embodiment of the present invention, the degree of bending of the curved portion BA may be varied by varying the etching amount. Table 1 is based on the reference (REF) when the length (L) of the curved portion (BA) is 10 mm in glass of 0.1T thickness (t) (see FIG. 3), and only the etching amount is controlled while other conditions are constant. This is experimental data showing that the degree of bending of the curved portion BA can be adjusted by doing so. In the table, the etching amount means the thickness of the lower surface of the curved portion BA removed through the etching process.

0.1T Glass DOL (D) (㎛) Etching amount (㎛) Curved part (BA) (mm) t (thickness) L (length) REF. - - 0.10 10.00 One
30
20 4.32 8.31 2 30 4.95 7.91 3 40 6.03 7.11

As another example, in the method of manufacturing the tempered glass 1 according to an embodiment of the present invention, the degree of bending of the curved portion BA may be varied by changing the DOL (D). Table 2 is a reference (REF) when the length (L) of the curved portion (BA) is 10 mm in glass of 0.1T thickness (t) (see FIG. 3), DOL (D) under constant conditions This is experimental data showing that the degree of bending of the curved portion BA can be adjusted by adjusting only.

0.1T Glass DOL (D) (㎛) Etching amount (㎛) Curved part (BA) (mm) t (thickness) L (length) REF. - - 0.10 10.00 One 10
20

2.23 9.24 2 20 3.16 8.65 3 30 4.32 8.31 4 40 4.15 7.91

As another example, in the method of manufacturing the tempered glass 1 according to an embodiment of the present invention, the degree of bending of the curved portion BA may be varied by varying the etching amount and DOL(D). Table 3 is based on the reference (REF) when the length (L) of the curved portion (BA) is 10 mm in glass of 0.1T thickness (t) (see FIG. 3), and the etching amount and/or other conditions are constant. Alternatively, it is experimental data showing that the degree of bending of the curved portion BA can be adjusted by adjusting the DOL (D).

0.1T Glass DOL (D) (㎛) Etching amount (㎛) Curved part (BA) (mm) t (thickness) L (length) REF. - - 0.10 10.00 One
10
20 2.23 9.24 2 30 2.81 8.38 3 40 3.58 7.73 4
20
20 3.16 8.65 5 30 3.68 8.37 6 40 4.84 7.97 7
30
20 4.32 8.31 8 30 4.95 7.91 9 40 6.03 7.11 10
40
20 4.15 7.91 11 30 4.81 7.43 12 40 6.35 6.47

Referring to FIG. 7 , the relationship between the surface thickness (etching amount) of the curved portion BA removed through the etching process and the compressive stress layer 20 formed during chemical strengthening will be described. FIG. 7 is an enlarged view of an AR area in FIG. 6 .

As shown in FIG. 7 and the above experimental example, as the etching process is performed on the lower surface of the curved portion BA, the thickness of the compressive stress layer 20 formed on the lower surface of the curved portion BA may be reduced. (Fig. 7 (a)), the compressive stress layer 20 may be removed (Fig. 7 (b)), and may be over-etched beyond the compressive stress layer 20 (Fig. 7 (c) ). An etching amount may be adjusted to correspond to a target degree of bending according to a designer's intention. However, it is preferable that the amount of etching is appropriately adjusted so as to prevent a decrease in strength caused by the complete removal of the compressive stress layer 20 formed on the lower surface of the curved portion BA.

Hereinafter, a tempered glass and a manufacturing method thereof according to another embodiment of the present invention will be described with reference to FIGS. 8 to 12 . 8 to 12 are cross-sectional views illustrating a process for manufacturing a tempered glass according to another embodiment of the present invention.

Referring to FIG. 8 , a glass substrate 10 for strengthening treatment is prepared. A flat portion FA and a curved portion BA extending from at least one side of the flat portion FA are defined in the glass substrate 10 . The flat part FA means a region having a planar shape after passing through a final process. The curved portion BA means a region having a curved shape that is bent after passing through a final process.

Referring to FIG. 9 , a strengthening process of strengthening the glass substrate 10 in which the flat portion FA and the curved portion BA are defined is performed. The strengthening process proceeds according to the chemical strengthening method. The chemical strengthening method is a method of forming a stress layer on a glass surface layer through ion substitution. The stress layer may be the compressive stress layer 20 . The driving force for ion replacement can be governed by the diffusion coefficient of individual ions with concentration gradient diffusion. For example, by immersing the glass substrate 10 in a salt bath (molten potassium nitrate) at 400 to 500 ° C. for a certain period of time, alkali metal ions (sodium ions) having a small ionic radius present in the surface layer of the glass substrate 10 can be induced to be substituted with an alkali metal ion (potassium ion) having a relatively large ionic radius. Accordingly, the compressive stress layer 20 is formed on the surface of the glass substrate 10 . The compressive stress layer 20 refers to an outer surface layer of the glass substrate 10 formed when relatively large ions invade the surface of the glass substrate 10 by ion exchange. As the compressive stress layer 20 is formed, the strength of the glass substrate 10 vulnerable to tensile stress may be increased. The strength of the glass substrate 10 may be further improved as the DOL(D) of the compressive stress layer 20 increases.

The tempered glass 1 according to another embodiment of the present invention is strengthened by a chemical strengthening method rather than a physical strengthening method, so that the thin glass substrate 10 can be strengthened, and manufacturing cost and manufacturing time can be reduced. Productivity and yield can be improved. In addition, it has the advantage of being able to be strengthened without additional deformation or physical processing of the glass substrate 10 .

Referring to FIG. 10 , a polishing pad 53 and a press 55 for providing a load to the polishing pad 53 are provided on the glass substrate 10 subjected to the tempering process. The polishing pad 53 is disposed on one of the upper and lower surfaces of the curved portion BA. The surface of the curved portion BA on which the polishing pad 53 is disposed may be determined according to a bending direction intended by a designer. In other words, the bending direction of the curved portion BA may be determined according to the position where the polishing pad 53 is disposed. For example, a designer may place the polishing pad 53 on the upper surface of the curved portion BA in order to bend the curved portion BA in an upward direction. Hereinafter, a case in which the polishing pad 53 is disposed on the upper surface of the curved portion BA in order to bend the curved portion BA in an upward direction will be described as an example.

Referring to FIG. 11 , a polishing process is performed on the surface of the tempered glass substrate 10 . The upper surface of the curved portion is in contact with the polishing pad 53 . A polishing load is applied to the upper surface of the curved portion from the press 55 via the polishing pad 53 . As shown, the polishing pad 53 may be repeatedly operated in a specific direction. A portion of the upper surface of the curved portion BA is removed by the repeated operation of the polishing pad 53 . In order to continuously perform the polishing process, polishing liquid and cleaning liquid may be selectively supplied during operation of the polishing pad 53, thereby increasing process efficiency and yield. Process conditions such as polishing load, polishing rate, and polishing time may be appropriately selected depending on the strength of the glass substrate and the like. Known techniques may be used for the shape and structure of the polishing pad 53, a polishing process method, and the like.

Referring to FIG. 12 , when the upper surface of the curved portion BA is removed by a polishing process, a difference in DOL (D) occurs between the upper surface where the polishing process is performed and the lower surface where the polishing process is not performed. As the compressive stress formed on the upper surface of the curved portion BA is reduced compared to the compressive stress formed on the lower surface, the curved portion BA is bent upward in response to the difference in compressive stress. At this time, as the polishing process is performed only on the curved portion BA, the thickness t2 of the curved portion BA is reduced compared to the thickness t1 of the flat portion FA. Accordingly, a step 30 is generated at the boundary between the curved portion BA and the flat portion FA.

The curved portion BA of the tempered glass according to the present invention may be formed by performing a polishing process with high precision. In the method for manufacturing tempered glass according to another embodiment of the present invention, a tempered glass having a curved portion BA having improved flatness and smoothness may be provided by using a polishing process.

<Second Embodiment>

Unlike the first embodiment, the second embodiment of the present invention is characterized by providing the tempered glass 201 with a reduced step 30 formed at the boundary between the flat portion FA and the curved portion BA. The step 30 formed at the boundary between the flat portion FA and the curved portion BA may be visually recognized from the outside and may be a factor deteriorating the aesthetics of the tempered glass 201 . In addition, foreign substances, etc. may be stacked on the stepped portion 30 formed at the boundary between the flat portion FA and the curved portion BA during the manufacturing process and/or distribution process, and the foreign matter may be visually inspected through the tempered glass 201. The visibility of the incident light may be deteriorated. In order to solve this problem, a tempered glass 201 and a method for manufacturing the tempered glass 201 with reduced steps 30 that may be formed at the boundary between the flat portion FA and the curved portion BA will be described below.

13 is a view showing a tempered glass according to a second embodiment of the present invention.

Referring to FIG. 13 , the tempered glass 201 according to the second embodiment of the present invention includes a flat portion FA and a curved portion BA. The flat portion FA means a region having a planar shape in the tempered glass 201 according to the present invention. The curved portion BA refers to a region having a curved shape by bending the tempered glass 201 according to the present invention. The curved portion BA is positioned to extend from the flat portion FA in at least one direction. A slope formed between one surface of the flat portion FA and one surface of the curved portion BA adjacent thereto is gentle. To this end, the curved portion BA has a different thickness from that of the flat portion FA. For example, the flat portion FA has a first thickness t1, and the curved portion BA has a thickness different from that of the flat portion FA, but may have different thicknesses t2 and t3 depending on the location. there is.

Referring to FIG. 14, a tempered glass 201 and a manufacturing method thereof according to an embodiment of the present invention will be described. 14 is a cross-sectional view illustrating a tempered glass and a process for manufacturing the tempered glass according to an embodiment of the present invention.

Referring to FIG. 14, an embodiment of the present invention is a glass substrate having a step 30 formed at the boundary between the tempered glass 1 according to the first embodiment, that is, the flat portion FA and the curved portion BA ( 210), a tempered glass 201 having a reduced step 30 is provided. In the tempered glass 201 formed through the processes of FIGS. 2 to 6 or FIGS. 8 to 12 , an etching process or a polishing process is performed on one surface of the curved portion BA to determine the thickness of the curved portion BA and the flat portion. The thickness of (FA) becomes different. That is, a portion of the thickness of one side of the curved portion BA is removed, so that the thickness t2 of the curved portion BA is reduced compared to the thickness t1 of the flat portion FA. Accordingly, a steep step 30 is formed at the boundary between the curved portion BA and the flat portion FA.

An additional polishing process is performed on the stepped portion formed at the boundary between the flat portion FA and the curved portion BA. An additional polishing process can be performed using known equipment and methods. By an additional polishing process, one surface of the glass substrate 210 on which the step is formed is removed. One surface removed may be the compressive stress layer 220 . As a partial region of the compressive stress layer 220 is removed, the degree of bending of the curved portion BA may vary. For convenience of explanation, a region of the curved portion BA in which an additional polishing process is performed is defined as a first curved portion BA1. In other words, the curved portion BA is defined as a first curved portion BA1 adjacent to the flat portion FA and a second curved portion BA2 spaced apart from the flat portion FA, and the first curved portion BA1 denotes an area in which an additional polishing process is performed. In this case, the thickness of the curved portion BA is formed to be thinner than the thickness of the flat portion FA, and the thickness of the first curved portion BA1 gradually decreases as the distance from the flat portion FA increases, and the second curved portion The thickness of portion BA2 is constant.

Since the purpose of the additional polishing process performed on the first curved portion BA1 is to remove the step 30 , it may be sufficient to remove only the compressive stress layer 220 in a narrow area. Therefore, it should be noted that the additional polishing process may not affect the degree of bending.

The tempered glass 201 according to an embodiment of the present invention in which the step difference 30 is reduced through an additional polishing process can prevent the step difference 30 from being visually recognized from the outside. In addition, it is possible to prevent a decrease in visibility that may occur due to the accumulation of foreign substances on the stepped portion 30 .

Referring to FIG. 15, a tempered glass 201 and a manufacturing method thereof according to another embodiment of the present invention will be described. 15 is a cross-sectional view illustrating a tempered glass and a process for manufacturing the tempered glass according to another embodiment of the present invention.

Referring to FIG. 15, another embodiment of the present invention is a glass substrate having a step 30 formed at the boundary between the tempered glass 1 according to the first embodiment, that is, the flat portion FA and the curved portion BA ( 210), a tempered glass 201 having a reduced step 30 is provided. In the tempered glass 201 formed through the processes of FIGS. 2 to 6 or FIGS. 8 to 12 , an etching process or a polishing process is performed on one surface of the curved portion BA to determine the thickness of the curved portion BA and the flat portion. The thickness of (FA) becomes different. That is, a portion of the thickness of one side of the curved portion BA is removed, so that the thickness t2 of the curved portion BA is reduced compared to the thickness t1 of the flat portion FA. Accordingly, a steep step 30 is formed at the boundary between the curved portion BA and the flat portion FA.

In order to reduce the level difference 30, a process of forming the filling layer 240 on the curved portion BA of the glass substrate 210 is performed. The filling layer 240 serves to fill the step 30 formed at the boundary between the curved portion BA and the flat portion FA of the glass substrate 210 . That is, the filling layer 240 is positioned so as to fill the step 30 formed along the boundary between the curved portion BA and the flat portion FA, so that one surface of the flat portion FA and the curved portion BA adjacent thereto are formed. One side should have a gentle slope.

The filling layer 240 may be formed on the entire surface of one side of the curved portion BA on which the step 30 is formed. In this case, the glass substrate 210 and the filling layer 240 are laminated on the curved portion BA of the tempered glass 201, and the thicknesses t2 and t3 of the curved portion BA are It gradually decreases as the distance increases (Fig. 15(a)). The filling layer 240 may be formed only on a partial surface of one side of the curved portion BA on which the step 30 is formed. That is, the curved portion BA may be defined as a first curved portion BA1 adjacent to the flat portion FA and a second curved portion BA2 spaced apart from the flat portion FA. In this case, the first curved portion BA1 refers to a region in which the filling layer 240 is stacked on the glass substrate 210 . In this case, the thickness of the curved portion BA of the tempered glass 201 is thinner than the thickness of the flat portion FA, and the thickness t2 of the first curved portion BA1 is far from the flat portion FA. The thickness t3 of the second curved portion BA2 is constant ((b) of FIG. 15).

The filling layer 240 is preferably a transparent resin that transmits light. For example, the filling layer 240 may include a transparent acryl-based resin, an epoxy-based resin, and a urethane-based resin. In addition, the filling layer 240 is preferably formed of a material having good adhesion to the glass substrate 210 . The filling layer 240 is preferably formed of a material having excellent optical properties in order to prevent deterioration in visibility of light incident to the user's naked eye through the glass substrate 210 and the filling layer 240 . In addition, the filling layer 240 is preferably a material having transmittance and refractive index equivalent to that of the glass substrate 210 .

The tempered glass 201 according to another embodiment of the present invention in which the step difference 30 is reduced through the formation of the filling layer 240 can prevent the step difference 30 from being visually recognized from the outside. In addition, it is possible to prevent a decrease in visibility that may occur due to the accumulation of foreign substances on the stepped portion 30 .

The filling layer 240 may function as a buffer layer formed on the curved portion BA to absorb an external force that may act on the tempered glass 201 . In detail, the curved portion BA of the tempered glass 201 according to the present invention may have a lower strength than the surrounding area because a part of the compressive stress layer 220 is removed. In this situation, another embodiment of the present invention further forms a filling layer 240 on the curved portion BA, thereby reducing deformation or cracking of the curved portion BA due to an external force supplied from the outside. Tempered glass 201 can provide.

Hereinafter, with reference to FIGS. 16 to 19 , a tempered glass 201 and a manufacturing method thereof according to another embodiment of the present invention will be described. 16 to 19 are cross-sectional views illustrating a process for manufacturing a tempered glass according to another embodiment of the present invention.

Referring to FIG. 16 , a glass substrate 210 for strengthening treatment is prepared. A flat portion FA and a curved portion BA extending from at least one side of the flat portion FA are defined in the glass substrate 210 . The flat part FA means a region having a planar shape after passing through a final process. The curved portion BA means a region having a curved shape that is bent after passing through a final process.

Referring to FIG. 17 , a strengthening process of strengthening the glass substrate 210 in which the flat portion FA and the curved portion BA are defined is performed. The strengthening process proceeds according to the chemical strengthening method. The chemical strengthening method is a method of forming a stress layer on a glass surface layer through ion substitution. The stress layer may be the compressive stress layer 220 . The driving force for ion replacement can be governed by the diffusion coefficient of individual ions with concentration gradient diffusion. For example, by immersing the glass substrate 210 in a salt bath (molten potassium nitrate) at 400 to 500° C. for a certain period of time, alkali metal ions (sodium ions) having a small ionic radius existing on the surface layer of the glass substrate 210 can be induced to be substituted with an alkali metal ion (potassium ion) having a relatively large ionic radius. Accordingly, the compressive stress layer 220 is formed on the surface of the glass substrate 210 . The compressive stress layer 220 refers to an outer surface layer of the glass substrate 210 formed when relatively large ions invade the surface of the glass substrate 210 by ion exchange. As the compressive stress layer 220 is formed, the strength of the glass substrate 210 vulnerable to tensile stress may be increased. The strength of the glass substrate 210 may be further improved as the depth of layer (DOL) (D) of the compressive stress layer 220 increases.

The tempered glass 201 according to another embodiment of the present invention is strengthened by a chemical strengthening method rather than a physical strengthening method, so that the thin glass substrate 210 can be strengthened and the manufacturing cost and manufacturing time can be reduced. Productivity and yield can be improved. In addition, it has the advantage of being able to be strengthened without additional deformation or physical processing of the glass substrate 210 .

Referring to FIG. 18 , a polishing process is performed on one surface of the curved portion BA of the tempered glass substrate 210 . The polishing process can be performed using known devices and methods. Hereinafter, a case in which the polishing process is performed on the upper surface of the curved portion BA will be described as an example. A portion of the upper surface of the curved portion BA is removed by the polishing process. In this case, the thickness of the curved portion BA gradually decreases as the distance from the flat portion FA increases through the polishing process. When viewed in cross section, an upper surface of the curved portion BA may have an oblique shape. Accordingly, an angle formed between one surface of the flat portion FA and one surface of the curved portion BA adjacent thereto is gentle.

Referring to FIG. 19 , when the upper surface of the curved portion BA is removed by a polishing process, a difference in DOL (D) occurs between the upper surface where the polishing process is performed and the lower surface where the polishing process is not performed. As the compressive stress formed on the upper surface of the curved portion BA is reduced compared to the compressive stress formed on the lower surface, the curved portion BA is bent upward in response to the difference in compressive stress. At this time, as the polishing process is performed only on the curved portion BA, the thicknesses t2 and t3 of the curved portion BA are reduced compared to the thickness t1 of the flat portion FA. In addition, the thicknesses t2 and t3 of the curved portion BA may vary depending on positions.

The curved portion BA of the tempered glass 201 according to another embodiment of the present invention may be formed by performing a polishing process with high precision. The method of manufacturing the tempered glass 201 according to another embodiment of the present invention may provide the tempered glass 201 having the curved portion BA with improved flatness and smoothness by using a polishing process.

The tempered glass 201 according to another embodiment of the present invention reduces the step 30 that may occur at the boundary between the flat portion FA and the curved portion BA, so that the step 30 is visually recognized from the outside. problems can be avoided. In addition, it is possible to prevent a decrease in visibility that may occur due to the accumulation of foreign substances on the stepped portion 30 .

Referring to FIG. 20 , an example of the structure of the curved portion BA on which the polishing process is performed will be described. FIG. 20 is an enlarged view of an area AR' in FIG. 19 .

As the polishing process is performed on the upper surface of the curved portion BA, the thickness of the compressive stress layer 220 formed on the upper surface of the curved portion BA may be reduced. In this case, the thickness of the curved portion BA may gradually decrease as the distance from the flat portion FA increases (FIG. 20(a)). As the polishing process is performed on the upper surface of the curved portion BA, the compressive stress layer 220 formed on a portion of the upper surface may be removed. That is, the compressive stress layer 220 may remain only in a portion of the curved portion BA adjacent to the flat portion FA. For example, the thickness of the curved portion BA of the area BA1 where the compressive stress layer 220 remains gradually decreases as the distance from the flat portion FA increases, and the area BA2 where the compressive stress layer 220 does not remain. The thickness of the curved portion BA of ) may be constant ((b) of FIG. 20). As the polishing process is performed on the upper surface of the curved portion BA, a portion of the curved portion BA may be removed beyond the compressive stress layer 220 to an area outside the compressive stress layer 220 (see FIG. 20 ). (c)). The thickness removal amount of the curved portion BA may be adjusted to correspond to a target degree of bending according to a designer's intention. However, it is preferable that the thickness removal amount of the curved portion BA be appropriately adjusted so as to prevent a decrease in strength caused by the complete removal of the compressive stress layer 220 formed on the upper surface of the curved portion BA.

<Third Embodiment>

The tempered glasses 1 and 201 according to the first and second embodiments of the present invention can be used in various fields. 21 is a view for explaining application fields of tempered glass according to the first and second embodiments of the present invention.

For example, referring to (a) of FIG. 21 , the tempered glass 1 or 201 according to the present invention may be a cover glass CW of a display device having a curved portion. The cover glass CW functions as a substrate protecting elements inside the display device. The display device may include a display panel (DP) having display elements and driving elements for displaying images, and a touch screen panel (TSP) that senses the movement of a user's hand and/or a conductor. In this case, the cover glass CW disposed on the upper portion of the touch screen panel TSP needs to be a thin tempered glass that is thin to prevent a decrease in touch sensing sensitivity and is not easily broken by external impact. In addition, it is necessary to use a cover glass (CW) including a curved portion in response to variously changing shape display devices. Accordingly, the tempered glass 1 or 201 according to the present invention can perform all of the above-described functions, and thus can be suitable as a cover glass CW of a display device.

As another example, referring to (b) of FIG. 21 , the tempered glass 1 or 201 according to the present invention may be a protective film PF that protects a cover glass of a display device. Tempered glass (hereinafter referred to as "tempered glass film") is used as a protective film PF to protect the cover glass CW of the display device DD. The tempered glass film PF needs to secure mechanical strength required to protect the cover glass CW provided on the outermost side of the display device DD. In addition, it needs to correspond to various release products in order to improve aesthetics and needs to be thin to prevent thickness increase. Therefore, the tempered glass 1, 201 according to the present invention can satisfy these demands, and is a tempered glass film PF for protecting the cover glass CW provided on the outermost surface of the display device DD. may be suitable as

<Fourth Embodiment>

Hereinafter, a method for manufacturing tempered glass according to a fourth embodiment of the present invention will be described with reference to FIG. 21 . 22 is a flow chart explaining a process for manufacturing a tempered glass according to a fourth embodiment of the present invention.

In the method for manufacturing tempered glass according to the fourth embodiment of the present invention, a step of preparing a glass substrate in which a flat portion and a curved portion are defined (S310), a step of first strengthening the glass substrate (S320), A step of performing a removal process on at least a partial region (S330), and a step of performing a secondary strengthening treatment on the glass substrate (S340).

The tempered glass manufacturing method according to the fourth embodiment of the present invention is substantially the same as the above-described tempered glass manufacturing methods of the present invention except for the step of performing the secondary tempering treatment on the glass substrate (S340). Therefore, only the second strengthening process (S340) of the glass substrate will be described below.

A compressive stress layer is formed on the surface of the glass substrate through primary strengthening treatment. At this time, when a portion of the thickness of the curved portion BA is removed, the compressive stress layer at the corresponding position is removed or the thickness is reduced. In other words, by the etching or polishing process, a compressive stress layer is not formed or a part of the thickness of the curved portion BA remains in a state where the compressive stress layer is partially removed. Some areas of the curved portion BA have lower strength than other areas of the glass substrate subjected to the strengthening treatment and are easily damaged from external impact. In order to solve this problem, a secondary strengthening process (S340) may be performed on the glass substrate on which the etching process or the polishing process has been performed.

The secondary strengthening process (S340) proceeds according to the chemical strengthening method. The chemical strengthening method is a method of forming a stress layer on a glass surface layer through ion replacement. The stress layer may be a compressive stress layer. The secondary strengthening process (S340) may be performed in the same method and/or process conditions as the primary reinforcing process (S320), or may be performed in a different method and/or process condition. For example, the secondary reinforcement process (S340) proceeds in the same way as the primary reinforcement process (S320), but the primary reinforcement process (S320) and process conditions, such as process time, stress layer formation thickness conditions, etc. You can proceed differently.

By the secondary strengthening process ( S340 ), the thickness of the compressive stress layer formed on some areas of the curved portion BA may be different from the compressive stress layer formed on other areas. If necessary, it may be desirable to perform the secondary strengthening process ( S340 ) only on the curved portion BA where the etching process or the polishing process has been performed. Accordingly, in the fourth embodiment according to the present invention, it is possible to provide a tempered glass whose strength does not decrease even after the etching process or the polishing process is performed by performing the secondary strengthening process (S340).

Through the above description, those skilled in the art will be able to make various changes and modifications without departing from the spirit of the present invention. Therefore, the technical scope of the present invention is not limited to the contents described in the detailed description of the specification, but should be defined by the claims.

1, 201: tempered glass 10, 210: glass substrate
FA: flat part BA: curved part
20, 220: compressive stress layer 30: step
240: filling layer PF: tempered glass film

Claims (18)

In the tempered glass comprising a glass substrate that has been strengthened and has a stress layer formed on its surface,
flat part; and
A curved portion extending and bending in at least one direction from the flat portion and having a thickness different from that of the flat portion;
An inclination between one surface of the flat part and one surface of the curved part adjacent to the one surface of the flat part gradually changes,
The curved portion includes a first curved portion adjacent to the flat portion and a second curved portion spaced apart from the flat portion,
The thickness of the first curved portion gradually decreases as the distance from the flat portion increases,
Tempered glass having a constant thickness of the second curved portion. According to claim 1,
The thickness of the curved portion is
Tempered glass that gradually decreases as the distance from the flat portion increases. delete According to claim 1,
Tempered glass further comprising a filling layer applied to one surface of the curved portion. According to claim 4,
The curved part,
A first curved portion adjacent to the flat portion and a second curved portion spaced apart from the flat portion,
The filling layer is
Tempered glass positioned only on the first curved portion. According to claim 4,
The filling layer is
Tempered glass that is a transparent resin containing at least one of an acrylic resin, an epoxy resin, and a urethane resin. According to claim 4,
The filling layer is
Tempered glass comprising a material having at least one of the same transmittance and refractive index as the glass substrate. A first step of preparing a glass substrate in which a flat portion and a curved portion extending in at least one direction from the flat portion are defined;
A second step of forming a stress layer on the surface of the glass substrate by strengthening the glass substrate;
a third step of bending the curved portion by performing a removal process on at least a portion of the surface of the curved portion; and
By the removal process, the step formed along the boundary between the flat part and the curved part is processed so that the slope formed by one surface of the flat part and one surface of the curved part adjacent to the one surface of the flat part is gradually changed. Including the fourth step,
The process of reducing the step is a method for manufacturing tempered glass that is a polishing process. According to claim 8,
The removal process,
A method for manufacturing tempered glass, which is any one of an etching process and a polishing process. delete According to claim 8,
The process of reducing the step,
A method for manufacturing tempered glass, which is a step of forming a filling layer on the surface of the curved portion where the removal step is performed. According to claim 8,
Tempered glass manufacturing method further comprising the step of subjecting the glass substrate to a secondary strengthening treatment. A first step of preparing a glass substrate in which a flat portion and a curved portion extending in at least one direction from the flat portion are defined;
A second step of forming a stress layer on the surface of the glass substrate by strengthening the glass substrate; and
A third step of bending the curved portion by performing a polishing process on at least a portion of the surface of the curved portion;
An inclination between one surface of the flat part and one surface of the curved part adjacent to the one surface of the flat part gradually changes,
Wherein the polishing process is a process of removing the stress layer. According to claim 13,
The polishing process,
A method for manufacturing tempered glass, which is a process of removing a portion of the thickness of the stress layer. 15. The method of claim 14,
The thickness of the curved portion is
A method for manufacturing tempered glass that gradually decreases as it moves away from the plane portion. 15. The method of claim 14,
The curved part,
A first curved portion where the stress layer remains and a second curved portion where the stress layer is removed,
The thickness of the first curved portion gradually decreases as the distance from the flat portion increases,
The thickness of the second curved portion is a constant tempered glass manufacturing method. delete According to claim 13,
Tempered glass manufacturing method further comprising the step of subjecting the glass substrate to a secondary strengthening treatment.

Images