KR20220031208A - Reinforced glass product and method of manufacturing the same - Google Patents

Abstract

A tempered glass article according to exemplary embodiments comprises a high-etching surface and a low-etching surface on both sides, respectively, and comprises a tempered glass body having a shape in which both ends of the low-etching surface are curved in a direction facing each other, wherein the strengthening depth of the high-etching surface is deeper than that of the low-etching surface. Curls are formed in one direction of the tempered glass article, and flexural properties in a curl direction can be improved.

Description

Tempered glass article and manufacturing method thereof

The present invention relates to a tempered glass article and a method for making the same.

Glass products are treated as essential components in a wide range of technological and industrial fields such as video and optical equipment such as monitors, cameras, VTRs, mobile phones, transportation equipment such as automobiles, various tableware, and construction facilities. Accordingly, glass having various physical properties is manufactured and used according to the characteristics of each industrial field.

In particular, as a flexible display device has recently been developed, the need for an upper transparent protective film having excellent bending properties and durability is increasing.

Conventionally, plastic organic materials such as polyester or acrylic have been used as the upper transparent protective film, but these materials have weak mechanical strength and are limited in durability, such as being deformed or damaged by repeated bending. Accordingly, tempered thin glass having excellent heat resistance, mechanical strength and hardness is gradually emerging as a material for an upper transparent protective film for flexible display devices.

However, in the case of tempered thin glass, there is a risk that the tempered thin glass is broken by the compressive stress caused by repeated bending in spite of its excellent strength.

Therefore, there is a need for a study on the tempered thin glass with improved folding durability while maintaining the excellent mechanical strength of the tempered thin glass.

Korean Patent Publication No. 10-2011-0049524 discloses a flexible display substrate using chemically tempered glass, but does not disclose a tempered thin glass for a flexible display including a tempered thin glass having excellent folding durability.

Republic of Korea Patent Publication No. 10-2011-0049524

One object of the present invention is to provide a tempered glass article having excellent flexural properties.

Another object of the present invention is to provide a method for manufacturing a tempered glass article having excellent flexural properties.

The present invention includes a tempered glass body including a high-etching surface and a low-etching surface on both sides, respectively, and both ends of the low-etching surface are bent in a direction facing each other, and the strengthening depth of the high-etching surface is the low-etching surface Deeper than the tempered depth of, provide tempered glass products.

In one embodiment of the present invention, the ratio of the strengthening depth of the low-etched surface to the strengthening depth of the high-etched surface may be 66 to 85%.

In one embodiment of the present invention, the ratio of the surface roughness of the low-etched surface to the surface roughness of the high-etched surface may be 50 to 80%.

In one embodiment of the present invention, the tempered glass body may include a glass surface-modified with potassium (K).

In one embodiment of the present invention, the ratio of the surface potassium content of the high-etched surface to the surface potassium content of the low-etched surface may be 60 to 95%.

In one embodiment of the present invention, the low-etched surface may be a non-etched surface.

In one embodiment of the present invention, the thickness of the tempered glass body may be 10 to 100㎛.

In one embodiment of the present invention, the amount of curl of the tempered glass body may be 5 to 25 mm.

In addition, the present invention comprises the steps of forming a thin glass plate by asymmetrically etching both sides of the glass plate; and chemically strengthening the surface of the glass sheet.

In one embodiment of the present invention, the step of forming the thin glass plate may be to etch only one surface of the original glass plate.

In one embodiment of the present invention, before etching the glass original plate, the step of masking one surface of the glass original plate may be further included.

In one embodiment of the present invention, both surfaces of the thin glass plate may be asymmetrically modified by potassium.

In one embodiment of the present invention, the thickness of the glass original plate may be 50 to 500㎛.

In one embodiment of the present invention, the thickness of the thin glass plate may be 10 to 100 ㎛.

In one embodiment of the present invention, the glass original plate may be etched by an acidic etchant.

Tempered glass products according to exemplary embodiments of the present invention may include a high-etching surface and a low-etching surface on both surfaces, and the degree of strengthening of each of the high-etching surface and the low-etching surface may be different. Accordingly, the tempered glass product may be bent in a direction in which both ends of the low-etched surface face each other.

In addition, the tempered glass article may have improved bending properties when applied to a device that is bent in a direction coincident with the bending direction.

In addition, according to exemplary embodiments of the present invention, it is possible to easily manufacture tempered glass products having different degrees of strengthening on both sides by etching both sides of the glass original plate with asymmetric strength and then chemically strengthening it.

1 is a schematic cross-sectional view illustrating a tempered glass article according to exemplary embodiments of the present invention.
2 to 4 are schematic conceptual views illustrating a method of manufacturing a tempered glass article according to exemplary embodiments.

Embodiments of the present invention provide a tempered glass product in which the etching degree of both surfaces is different and both ends of the low-etched surface are bent in a direction facing each other, and a method of manufacturing the same. Curls are formed in one direction, so that flexural properties in the curl direction may be improved.

In the present specification, the surface compressive stress (CS; Compressive Stress) may mean a compressive stress in the outermost surface of the glass.

The surface compressive stress may decrease from the surface of the glass toward the inside of the glass. In this case, the depth to the point at which the surface compressive stress becomes substantially zero may be defined as the depth of reinforcement (DOL).

Surface compressive stress and strengthening depth can be measured using a surface stress meter (FSM-6000LE).

Hereinafter, embodiments of the present invention will be described in detail. However, this is merely exemplary and the present invention is not limited to the specific embodiments described by way of example.

1 is a schematic cross-sectional view illustrating a tempered glass article according to exemplary embodiments of the present invention.

Referring to FIG. 1 , a tempered glass article 10 according to exemplary embodiments includes a tempered glass body 100 , a high-etching surface 102 , and a low-etching surface 104 .

In one embodiment of the present invention, the tempered glass body 100 may include chemically strengthened glass. Chemical strengthening may be, for example, the substitution of atoms with a small ionic radius on the glass surface with an atom with a large ionic radius.

In an embodiment of the present invention, the tempered glass body 100 may include a glass modified with potassium (K). For example, the glass may contain sodium (Na) ions, and when the glass is immersed in a solution containing a potassium source such as potassium nitrate (KNO ₃ ), at least a portion of the sodium ions are replaced with potassium ions. can be Compressive stress may be applied to the surface of the glass by such potassium modification, and flexibility and impact resistance may be increased.

In some embodiments, a depth of substitution (DOL) of the potassium-modified glass may be 5 to 15% of the total thickness. The substitution depth may mean a depth from the surface of the glass to the deepest point where sodium ions are substituted with potassium ions.

In an embodiment of the present invention, the tempered glass body 100 may include an aluminosilicate-based glass having an Al ₂ O ₃ content of 15% by weight or more.

In the present invention, one surface of the tempered glass body 100 may be defined as a highly etched surface 102 . In addition, the other surface of the tempered glass body 100 may be defined as a low-etched surface 104 .

As used herein, the terms "high-etching surface" and "low-etching surface" express a relative degree of etching. For example, a "high etched surface" may mean a surface etched with relatively strong strength compared to a "low etched surface". In addition, the "low-etched surface" may mean a surface etched with a weaker strength than a "high-etched surface".

In an embodiment of the present invention, the high-etched surface 102 may have a higher surface strengthening degree (surface modification degree) than the low-etched surface 104 . For example, the high-etching surface 102 may have a protective film on the glass surface removed by relatively strong etching, and the molecular structure of the glass surface may be at least partially damaged. Chemical treatment can be easily performed on the already damaged surface of the high-etched surface 102 . Accordingly, the degree of surface strengthening of the high-etched surface 102 may be higher than that of the low-etched surface 104 .

When the degree of surface strengthening of the highly etched surface 102 is higher than that of the low etched surface 104 , asymmetric surface compressive stress may be formed on both surfaces of the tempered glass body 100 . For example, the surface compressive stress of the low-etched surface 104 is greater than that of the high-etched surface 102 , so that both ends of the low-etched surface 104 may be bent in a direction facing each other.

The tempered glass may have some flexibility in upper and lower directions. When the tempered glass itself has a curved shape in a specific direction, flexibility in a direction coincident with the curved direction may be further improved. In addition, it may have a predetermined flexibility with respect to the direction opposite to the bent direction. For example, a curved shape may have stable flexibility with respect to a shape developed in a plane.

In the case of a typical flexible device, the folding direction may be limited to one direction. Specifically, in the flexible device, a flat shape in an unfolded state and a folding shape in a folded state in one direction may be continuously converted to each other.

When the direction of the curl of the tempered glass product 10 (the direction in which both ends of the low-etched surface 104 are folded to face each other) is applied to match the folding direction of the flexible device, the bending characteristics can be significantly improved, and the flat shape stable durability can be ensured.

The low-etched surface 104 is provided as a surface opposite to the high-etched surface 102 , and the degree of reinforcement is lower than that of the high-etched surface 102 . Accordingly, the low-etched surface 104 may have a greater surface compressive stress than the high-etched surface 102 . Accordingly, the tempered glass product 10 may be bent in a direction in which the high etching surface 102 having a small surface compressive stress expands or extends.

In some embodiments, the low-etched surface 104 may include a substantially unetched non-etched surface. In this case, the difference in the degree of reinforcement of each surface may be further increased. Accordingly, the difference in physical properties with respect to the highly etched surface 102 may increase.

In one embodiment of the present invention, the reinforcement depth (reinforcement thickness) of the high-etching surface 102 may be deeper than the strengthening depth of the low-etching surface 104 .

In one embodiment of the present invention, the strengthening depth of the low-etched surface 104 may be 15% or more smaller than the strengthening depth of the high-etched surface 102 . In this case, a predetermined amount of curls may be formed in the tempered glass product 10 , and bending characteristics in the direction in which the curls are formed may be improved.

In some embodiments, the ratio of the strengthening depth of the low-etching surface 104 to the strengthening depth of the high-etching surface 102 may be 66 to 85%. When the ratio of the strengthening depth of the low-etching surface 104 to the strengthening depth of the high-etching surface 120 is less than 66%, when the curled tempered glass product 10 is flattened, in the center of the curl in the reverse direction of the curl Excessive stress may be applied. Therefore, a crack may occur in the center of the curl.

In one embodiment of the present invention, the surface compressive stress in the low-etching surface 104 may be greater than the surface compressive stress in the high-etching surface (102).

In some embodiments, the surface compressive stress of the low-etched surface 104 may be 15% or more greater than the surface compressive stress of the high-etched surface 102 . In this case, curls may be formed naturally in a direction in which both ends of the low-etched surface 104 are folded with each other. Accordingly, crack resistance may be improved when the low-etched surface 104 is bent in the folding direction.

In some embodiments, the ratio of the surface compressive stress of the low-etched surface 104 to the surface compressive stress of the high-etched surface 102 may be 115 to 140%. When the ratio of the surface compressive stress of the low-etched surface 104 to the surface compressive stress of the high-etched surface 102 exceeds 140%, reverse cracks may occur when the tempered glass product 10 is spread in parallel.

In some embodiments, the hardening depth of the high etch surface 102 may be between 3 and 30 μm. In addition, the depth of reinforcement of the low-etched surface 104 may be 2 to 25 μm.

In one embodiment of the present invention, the ratio of the strengthening depth of the low-etching surface 104 to the strengthening depth of the high-etching surface 102 may be 66 to 85%.

In an embodiment of the present invention, the surface roughness of the high-etching surface 102 may be greater than the surface roughness of the low-etching surface 104 .

In some embodiments, the surface roughness of the highly etched surface 102 may be 0.02 to 0.5 nm. The surface roughness of the low-etched surface 104 may be 0.01 to 0.4 nm.

In some embodiments, the ratio of the surface roughness of the low-etching surface 104 to the surface roughness of the high-etching surface 102 may be 50 to 80%.

In an embodiment of the present invention, the surface potassium content of the low-etching surface 104 may be greater than the surface potassium content of the high-etching surface 102 .

In some embodiments, the ratio of the surface potassium content of the high-etching surface 102 to the surface potassium content of the low-etching surface 104 may be 60 to 95%.

In one embodiment of the present invention, the thickness of the tempered glass body 100 may be 10 to 100㎛. When the thickness of the tempered glass body 100 is less than 10 μm, sufficient hardness and strength may not be secured, so that impact resistance may be lowered and fracture may occur during bending. In addition, when the thickness of the tempered glass body 100 is more than 100 μm, the bending resistance of the tempered glass product 10 may be reduced. More preferably, the thickness of the tempered glass body 100 may be 30 to 80 ㎛.

In one embodiment of the present invention, the amount of curl of the tempered glass body 100 may be 5 to 25 mm. As used herein, the term “curl amount” may mean a difference between the height of the central point of the tempered glass (eg, the lowest point of the upper surface of the tempered glass) and the height of a point separated by 30 mm from the central point. When the amount of curl of the tempered glass body 100 is less than 5 mm, the effect of improving the bending properties in a specific direction may be insufficient. When the amount of curl of the tempered glass body 100 is greater than 25 mm, it may be difficult to deform and maintain the tempered glass product 10 in a planar shape.

2 to 4 are schematic conceptual views illustrating a method of manufacturing a tempered glass article according to exemplary embodiments.

Referring to FIG. 2 , the glass disk 200 may include a preliminary high-etched surface 202 and a preliminary low-etched surface 204 . At this time, one surface of the glass original plate 200 may be defined as a preliminary high-etched surface 202 . In addition, the other surface of the glass original plate 200 may be defined as a preliminary low-etched surface (204).

The size of the arrow shown in FIG. 2 may indicate the degree of etching. The etching degree can be adjusted by asymmetrically setting the application direction, application amount, and application time of the etchant. In this case, the etchant may be applied by a method such as spray spraying, dipping, or application.

In some embodiments, the etchant may be an acidic aqueous solution containing hydrofluoric acid. For example, the etchant may be 1 wt% to 20 wt% of hydrofluoric acid, 0.1 wt% to 5 wt% ammonium fluoride, 1 wt% to 20 wt% inorganic acid, 1 wt% to 10 wt% organic acid or the organic acid of salt, and water such that the total weight of the total composition is 100% by weight.

In some embodiments, the inorganic acid is sulfuric acid (H ₂ SO ₄ ), hydrochloric acid (HCl), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ), sulfamic acid (SO ₃ HNH ₂ ), perchloric acid (HClO ₄ ) , chromic acid (HCrO ₄ ), sulfurous acid (H ₂ SO ₃ ), nitrous acid (HNO ₂ ), and the like may include any one or more selected.

In some embodiments, the organic acid is carboxylic acid, dicarboxylic acid, tricarboxylic acid (tricarboxlicacid), tetracarboxylic acid, acetic acid (acetic acid), butanoic acid (butanoic acid), citric acid ( citric acid, formic acid, gluconic acid, glycolic acid, malonic acid, oxalic acid, pentanoic acid, sulfobenzoic acid , sulfosuccinic acid, sulfophthalic acid, salicylic acid, sulfosalicylic acid, benzoic acid, lactic acid, glyceric acid, succinic acid From (succinic acid), malic acid (malic acid), tartaric acid (tartaric acid), isocitric acid (isocitric acid), propenoic acid (propenoic acid), imminodiacetic acid (imminodiacetic acid), ethylenediaminetetraacetic acid (EDTA; ethylenediaminetetraacetic acid) may include any one or more selected

In some embodiments, the water may be deionized water having a resistivity of 18 MΩ/cm or more at 25°C.

For example, when the etchant is sprayed in the direction of the preliminary high-etching surface 202 , the preliminary high-etching surface 202 is etched a lot, and the preliminary low-etching surface 204, which is the opposite surface, may be less etched.

The preliminary high-etched surface 202 may be etched relatively much to form the high-etched surface 102 . In addition, the preliminary low-etched surface 204 may be etched relatively little to form the low-etched surface 104 .

In one embodiment of the present invention, the thickness of the glass original plate 200 may be 50 to 500㎛. When the thickness of the glass disc 200 is less than 50 μm, the strength and hardness of the disc itself are too weak, so that impact resistance and bending resistance may be reduced. In addition, when the thickness of the glass original plate 200 is greater than 500 μm, it may be difficult to etch the thickness of the tempered glass body 100 within a desired range (eg, 100 μm or less).

A thin glass plate 206 may be formed by asymmetric etching.

In one embodiment of the present invention, the thickness of the thin glass plate 206 may be 10 to 100 ㎛. When the thickness of the thin glass plate 206 is less than 10 μm, sufficient hardness and strength may not be secured, so that impact resistance may be lowered and fracture may occur during bending. In addition, when the thickness of the thin glass plate 206 is more than 100 μm, the bending resistance of the tempered glass product 10 may be reduced. More preferably, the thickness of the thin glass plate 206 may be 30 to 80 μm.

The thin glass plate 206 may be chemically strengthened after being cut to a desired size. For the cutting, methods such as wheel cut laser cone, water jet cut, sand blast cut, ultrasonic cut, and air jet cut may be used without limitation.

The cut surface of the thin glass plate 206 may be polished by a non-limiting method such as diamond chuck polishing, laser melt polishing, chemical polishing, brushing, thermal polishing, or the like.

The polished glass plate 206 may have a surface wound repaired through an acid solution treatment or heating process such as hydrofluoric acid, hydrochloric acid, nitric acid, or the like.

Referring to FIG. 3 , an etching mask 210 may be disposed on the preliminary low-etched surface 204 of the glass original plate 200 . The etch mask 210 may mask the preliminary low-etched surface 204 to substantially prevent the preliminary low-etched surface 204 from being etched in an asymmetric etching process. In this case, the preliminary low-etched surface 204 may be provided as a non-etched surface.

The etch mask 210 may use, without limitation, a mask material resistant to an etchant such as hydrofluoric acid, hydrochloric acid, or nitric acid. The etching mask 210 may be removed after completion of the asymmetric etching process.

Referring to FIG. 4 , the manufactured thin glass plate 206 may be chemically strengthened. The ion displacement solution 230 may be used for chemical strengthening. The chemical strengthening may be performed by immersing the thin glass plate 206 in the ion displacement solution 230 accommodated in the reaction vessel 220 .

In one embodiment of the present invention, the ion displacement solution 230 is potassium nitrate (KNO ₃ ), potassium hydroxide phosphate (K ₂ HPO ₄ ), potassium chloride (KCl), potassium phosphate (K ₂ PO ₄ ) Potassium sources such as may include Potassium ions included in the potassium source may be substituted with sodium ions on the surface of the thin glass plate 206 . As sodium ions with a small radius are replaced with potassium ions with a large radius, compressive stress is applied to the surface of the glass to form tempered glass.

A high-etching surface and a low-etching surface (non-etching surface) of the thin glass plate 206 may be chemically strengthened asymmetrically. For example, the degree of potassium cleavage of the high-etching surface and the low-etching surface may be different.

Hereinafter, preferred embodiments are presented to help the understanding of the present invention, but these examples are merely illustrative of the present invention and do not limit the appended claims, and are within the scope and spirit of the present invention. It is obvious to those skilled in the art that various changes and modifications are possible, and it is natural that such variations and modifications fall within the scope of the appended claims.

[Examples 1 to 5]

Samples were prepared by cutting and processing aluminosilicate glass with a thickness of about 100 μm to 50×100 mm.

Both sides of the prepared sample were etched by spraying an etching solution containing hydrofluoric acid (including 5 to 10% hydrofluoric acid, sulfuric acid, nitric acid, surfactant and water). Next, the etched glass was washed with water. At this time, the etching degree of both sides of the sample was adjusted to be different from each other by controlling the injection amount (injection flow rate) of the etchant.

The sample, etched on both sides differently, was chemically strengthened by immersion in an ion replacement solution (Mitsubishi Chemical Co., Ltd., KNO ₃ 99.99%) containing potassium nitrate for 30 minutes.

The depth of penetration of potassium ions by chemical strengthening (strengthening depth, DOL) was controlled as described in Table 1 below according to the etching degree of both sides of the glass.

The surface compressive stress and strengthening depth of the prepared tempered glass product samples were measured using a surface glass stress analyzer (ORIHARA, FSM-6000LE).

[Comparative example]

Samples were prepared by cutting and processing aluminosilicate glass with a thickness of about 100 μm to 50×100 mm.

A tempered glass product sample was prepared in the same manner as in Example, except that both sides of the prepared sample were etched to the same extent.

Experimental Example: Curl direction flexural property evaluation

The tempered glass product samples prepared in Examples and Comparative Examples are bent so that the radius of curvature of the fold is 5 mm in the direction in which the curl is formed (the direction in which both ends of one side are folded to face each other), so that both ends of the sample are parallel to each other The flexural properties were evaluated by repeating the process (cycle) of completely unfolding the sample so that both ends were positioned on the same plane.

Flexural properties were evaluated according to the following criteria.

O: No cracks after 200,000 cycles

△: cracks occur during 100,000 to 200,000 cycles

X: Crack occurred before 100,000 cycles

reinforcement depth
(μm) surface compressive stress
(MPa) reinforcement depth
ratio
(Low etch side/high etch side)
(%) surface
compressive stress
ratio
(Low etch side/high etch side)
(%) curl direction
Flexural Characteristics Example 1 antiquity 8.21 580 74.5 135.0 O low etched side 6.12 783 Example 2 antiquity 5.50 764 75.1 128.4 O low etched side 4.13 981 Example 3 antiquity 13.20 453 74.5 117.4 O low etched side 9.84 532 Example 4 antiquity 6.58 695 76.3 124.7 O low etched side 5.02 867 Example 5 antiquity 7.64 595 76.4 133.6 O low etched side 5.84 795 comparative example side 1 6.1 727 100.2 100.3 X 2nd side 6.2 725

Referring to Table 1, compared to the comparative example sample in which the etching degree and the strengthening degree of both sides of the prepared glass-reinforced product sample are substantially the same, the strengthening depth and the surface compressive stress between the low-etching surface and the high-etching surface are different. In the example sample, it can be seen that the curl direction flexural property is remarkably improved.

10: tempered glass products
100: tempered glass body
102: high etching plane
104: low etched surface

Claims (15)

A tempered glass body including a high-etched surface and a low-etched surface on both sides, respectively, and both ends of the low-etched surface are bent in a direction facing each other,
The strengthening depth of the high-etching surface is deeper than the strengthening depth of the low-etching surface, tempered glass products. According to claim 1,
The ratio of the strengthening depth of the low-etching surface to the strengthening depth of the high-etching surface is 66 to 85%, a tempered glass article. According to claim 1,
The ratio of the surface roughness of the low-etched surface to the surface roughness of the high-etched surface is 50 to 80%, tempered glass article. According to claim 1,
wherein the tempered glass body comprises a glass surface-modified with potassium. According to claim 1,
The ratio of the surface potassium content of the high-etching surface to the surface potassium content of the low-etching surface is 60 to 95%, tempered glass article. According to claim 1,
The low-etched surface is a non-etched surface, a tempered glass article. According to claim 1,
The thickness of the tempered glass body is 10 to 100 ㎛, tempered glass article. According to claim 1,
wherein the amount of curl of the tempered glass body is 5 to 25 mm. forming a thin glass plate by asymmetrically etching both surfaces of the glass original plate; and
A method of manufacturing a tempered glass article, comprising chemically strengthening the surface of the glass sheet. 10. The method of claim 9,
Forming the thin glass plate is a method of manufacturing a tempered glass product by etching only one surface of the glass original plate. 10. The method of claim 9,
Before etching the glass original plate, the method of manufacturing a tempered glass article further comprising the step of masking one surface of the glass original plate. 10. The method of claim 9,
Both sides of the glass sheet are asymmetrically modified by potassium, a method for producing a tempered glass article. 10. The method of claim 9,
The thickness of the glass original plate is 50 to 500 ㎛, a method of manufacturing a tempered glass product. 10. The method of claim 9,
The thickness of the glass sheet is 10 to 100 μm, a method of manufacturing a tempered glass article. 10. The method of claim 9,
The glass original plate is etched by an acidic etchant, a method of manufacturing a tempered glass article.

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