CN116924699A - Chemical strengthening method for glass raw sheet, low-warpage value strengthened glass, cover plate glass and display - Google Patents

Abstract

The invention relates to the field of chemical strengthening of glass, specifically a method of chemical strengthening of original glass sheets, low warpage value strengthened glass, cover glass and displays. The chemical strengthening method of glass original sheets provided by the invention includes the following steps: S1) placing the preheated glass original sheets in molten salt for wet ion exchange; S2) placing the wet ion exchanged glass original sheets in step S1) The sheet is subjected to dry ion exchange; S3) annealing the original glass sheet after dry ion exchange in step S2). Compared with the traditional method, the present invention adds a step of dry ion exchange, so that the original glass sheet is not easily bent during the chemical strengthening process, and solves the problem that glass is prone to warping during the production and manufacturing process of existing strengthened glass. Experiments show that the surface compressive stress of the glass obtained by the present invention reaches the standard, and the warpage value is reduced from 0.28mm to 0.15mm, which is reduced by nearly 50%.

Description

A chemical strengthening method for original glass sheets, low warpage value strengthened glass, and cover glass and monitor

Technical field

The invention relates to the field of chemical strengthening of glass, specifically a method for chemical strengthening of original glass sheets, low warpage value strengthened glass, cover glass and displays.

Background technique

Chemical strengthening can improve the strength, scratch resistance and impact resistance of ultra-thin cover glass. Chemically strengthened ultra-thin cover glass can meet the performance requirements of mobile displays such as mobile phones and tablet computers.

There are two production processes for cover glass: overflow method and float method. Due to the huge investment amount in the overflow method, the float production process is mainly used for the production of original cover glass sheets on the market. The glass plate forming in the float production process is to flow high-temperature molten glass on top of the molten tin liquid. After being flattened, polished, thinned and cooled, it leaves the tin liquid and enters the annealing furnace. The entire process is completed on the surface of the tin liquid, and one side is in contact with the tin liquid (called the tin surface), and the other side is in contact with the protective gas (called the air surface), resulting in the inevitable diffusion of tin ions to the lower surface of the glass. ;The final glass product shows different chemical compositions between the tin surface and the air surface, and both are different from the composition of the glass body. The difference in chemical composition between the tin surface and the air surface is an inherent problem of cover glass produced by the float process. Chemical strengthening of cover glass produced by the float process means immersing the glass in a molten salt (such as potassium nitrate) containing an alkali metal ion with a radius larger than the alkali metal ion in the glass at a temperature not higher than the glass transition point (Tg). , ion exchange occurs between the glass and the molten salt. For example, K ⁺ in the molten salt replaces Na ⁺ in the glass. K ⁺ (0.133nm) with a large ion radius replaces the position vacated by Na ⁺ (0.099nm) with a small ion radius. , due to the volume difference between exchanged ions, the surface is "crowded", forming surface compressive stress. When an external force acts on the surface, this part of the compressive stress must first be offset, thus improving the mechanical strength of the glass. To achieve the purpose of glass strengthening.

During the chemical strengthening process of float ultra-thin alkali aluminosilicate glass, the inconsistent composition on both sides of the glass affects the ion exchange rate, making the CS (surface compressive stress) and DOL (ion exchange depth) on both sides of the cover glass inconsistent, resulting in The glass bulges and warps toward the atmosphere surface. This warping seriously affects the promotion of domestic ultra-thin alkali-aluminosilicate glass and its use by downstream customers.

Contents of the invention

In view of this, the technical problem to be solved by the present invention is to provide a chemical strengthening method for the original glass sheet, low warpage value tempered glass, cover glass and display. The chemical strengthening method provided by the present invention can strengthen the original glass sheet. A strengthened glass with high compressive stress and low warpage value is obtained.

The invention provides a chemical strengthening method for original glass sheets, which includes the following steps:

S1) Place the preheated glass original piece in molten salt for wet ion exchange;

S2) Perform dry ion exchange on the original glass sheet after wet ion exchange in step S1);

S3) Anneal the original glass sheet after dry ion exchange in step S2).

The dry ion exchange described in the present invention is specifically: after the wet ion exchanged glass original piece is completely taken out from the molten salt, it is directly insulated without any treatment. At this time, the molten salt remaining on the surface of the original glass piece will continue to damage the glass. The original piece was subjected to dry ion exchange. The present invention has no special restrictions on the medium in which the original glass sheet is placed during dry ion exchange, and it suffices to be completely placed outside the molten salt; in some embodiments of the present invention, the original glass sheet after wet ion exchange is directly placed After the glass sheet is taken out from the molten salt, the original glass sheet after wet ion exchange is in the air and is directly kept warm without any treatment, that is, dry ion exchange is performed. The temperature of dry ion exchange in the present invention is 360°C to 450°C, preferably 370°C to 440°C, more preferably 380°C to 430°C, and more preferably 400°C to 420°C; the dry ion exchange The time is 0.1h to 4h, preferably 0.3h to 3h, more preferably 0.5h to 2h, even more preferably 1h to 1.5h.

The wet ion exchange of the present invention is a method of using molten salt to ion exchange glass in the glass chemical strengthening process well known to those skilled in the art. The preheated glass original piece is placed in the molten salt. Specifically, the preheated glass is placed in the molten salt. The final piece of glass is completely placed in the molten salt. The temperature of wet ion exchange in the present invention is 360°C to 450°C, preferably 370°C to 440°C, and more preferably 380°C to 430°C; the time of wet ion exchange is 0.5h to 8h, preferably 1h to 7h, more preferably 2h to 6h. The molten salt of the present invention is selected from alkali metal ion molten salts. In some embodiments, the molten salt is selected from at least one or two of potassium nitrate molten salt, sodium nitrate, and lithium nitrate. In other embodiments, the molten salt is selected from a mixed molten salt with a mass percentage of 99.8% KNO ₃ and 0.2% NaNO ₃ .

The inventor of the present application creatively discovered that the original glass sheet after wet ion exchange in the molten salt is directly placed outside the molten salt for dry ion exchange. Through such sequential wet ion exchange and dry ion exchange, the traditional glass sheet can be replaced. Ion exchange can ensure that the original glass sheet has higher compressive stress and lower warpage value after strengthening. The present invention also optimizes the temperature and time in the wet ion exchange and dry ion exchange processes, thereby further reducing the warpage value of the glass. The temperature of the wet ion exchange in the present invention is not lower than the temperature of the dry ion exchange; the time of the wet ion exchange is not less than the time of the dry ion exchange.

The chemical strengthening method of the original glass sheet provided by the present invention first places the preheated original glass sheet in molten salt for wet ion exchange. Specifically, in the present invention, the original glass sheet is first preheated to obtain a preheated original glass sheet, and then the preheated original glass sheet is completely placed in molten salt for wet ion exchange. The preheating temperature in the present invention is 360°C to 450°C, preferably 370°C to 440°C, and more preferably 380°C to 430°C; the preheating time is 1h to 3h. The wet ion exchange in the present invention is the same as above and will not be described again.

In the present invention, the preheated glass original sheet is subjected to wet ion exchange, and then the wet ion exchanged glass original sheet is subjected to dry ion exchange. The dry ion exchange in the present invention is the same as above and will not be described again.

In the present invention, the original glass sheet after wet ion exchange is subjected to dry ion exchange, and then the original glass sheet after dry ion exchange is annealed to complete the chemical strengthening of the original glass sheet. The annealing temperature in the present invention is 360°C to 450°C, preferably 370°C to 440°C, and more preferably 380°C to 430°C; the annealing time is 2h to 4h.

The present invention provides a kind of low warpage value strengthened glass, which is obtained by strengthening the original glass sheet by the above-mentioned chemical strengthening method. In some embodiments of the present invention, the size of the low-warpage tempered glass of the present invention is 7 inches, which is obtained by strengthening the 7-inch original glass sheet. The thickness of the low-warp strengthened glass of the present invention is 0.1 mm to 2 mm, and the thickness of the original glass sheet is the same as the thickness of the finally obtained low-warp strengthened glass.

In some embodiments of the present invention, the size of the low-warp strengthened glass of the present invention is 7 inches, and the warpage value of the low-warp strengthened glass is 0.10 mm to 0.15 mm; the low warp Value The surface compressive stress (CS) value of the strengthened glass is 450MPa to 1000MPa, preferably 500MPa to 900MPa, and more preferably 550MPa to 800MPa. The stress layer depth (DOL value) of the low-warp value strengthened glass of the present invention is 8 μm to 60 μm, preferably 10 μm to 55 μm, and more preferably 12 μm to 50 μm. The low-warp value strengthened glass provided by the present invention not only has a compressive stress that can meet the usage requirements, but also has a low warp value.

In some embodiments of the present invention, the components of the original glass sheet of the present invention include, in terms of mass percentage of oxides: 62% to 73% SiO ₂ ; 4% to 13% Al ₂ O ₃ ; 0.5 to 7.8% CaO; 4% to 11% MgO; 10% to 16% _Na2O ; and 0.5% to 3% _K2O . In other embodiments of the present invention, the components of the original glass sheet of the present invention include, in terms of mass percentage of oxides: 58% to 73% SiO ₂ ; 8% to 18% Al ₂ O ₃ ; 0.2 % to 3% B ₂ O ₃ ; 4% to 11% MgO; 10% to 20% Na ₂ O; and 0.5% to 8% K ₂ O. In one embodiment, the components of the original glass sheet of the present invention include, in terms of mass percentage of oxides: 69% SiO ₂ ; 5% Al ₂ O ₃ ; 6.5% CaO; 4.5% MgO; 14 % Na ₂ O; and 1% K ₂ O. In one embodiment, the components of the original glass sheet of the present invention include, in terms of mass percentage of oxides: 58% SiO ₂ ; 16% Al ₂ O ₃ ; 1% B ₂ O ₃ ; 5% MgO; 15% _Na2O ; and 5% _K2O .

The present invention also provides a cover glass, which is prepared from the above-mentioned low-warp value tempered glass. Since the above-mentioned low-warp tempered glass has a low warpage value, it can be used as cover glass in displays for various devices such as mobile phones, tablet computers, and televisions. The present invention provides a display having the above-mentioned cover glass. The display of the present invention includes but is not limited to one or more of a mobile phone display, a tablet computer display, and a television display.

The invention provides a chemical strengthening method for original glass sheets, low warpage value strengthened glass, cover glass and a display. The chemical strengthening method of the original glass sheet provided by the present invention includes the following steps: S1) placing the preheated original glass sheet in molten salt for wet ion exchange; S2) placing the wet ion exchanged original glass sheet in step S1) The sheet is subjected to dry ion exchange; S3) annealing the original glass sheet after dry ion exchange in step S2). Compared with the three steps of preheating, ion exchange and annealing in traditional chemical strengthening manufacturing, the strengthening method of the original glass sheet of the present invention adds a dry ion exchange, so that during the chemical strengthening process of the original glass sheet, The glass is not easy to bend, which solves the technical problem that the glass is prone to warping during the existing chemically strengthened glass production and manufacturing process. Experiments show that the compressive stress on the glass surface obtained by using the chemical strengthening method of the present invention can not only meet the needs of downstream customers, but also reduce the warpage value of 7-inch glass from 0.28mm to 0.15mm, that is, the warpage value is reduced by nearly 50%.

Detailed ways

The invention discloses a chemical strengthening method for original glass sheets, low warpage value strengthened glass, cover glass and a display. Those skilled in the art can learn from the contents of this article and appropriately improve the implementation of process parameters. It should be noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are deemed to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments. Relevant persons can obviously modify or appropriately change and combine the methods and applications herein without departing from the content, spirit and scope of the present invention to implement and apply the present invention. Invent technology.

The original glass sheet to be chemically strengthened used in Examples 1 to 3 and Comparative Examples 1 to 3 of the present application has a thickness of 0.7 mm and a size of 7 inches. Its components include:

69% _SiO2 ; 5% _Al2O3 ; 6.5% CaO; 4.5 MgO; 14% _Na2O ; and 1 _{% K2O} .

The original glass sheet to be chemically strengthened used in Example 4 and Comparative Example 4 of the present application has a thickness of 0.7 mm and a size of 7 inches. Its components include: in terms of mass percentage of oxides:

58% _SiO2 ; 16% _Al2O3 ; 1% _{B2O3 ;} 5% MgO; ₁₅ % _Na2O ; and 5% _K2O .

The present invention will be further elaborated below in conjunction with the examples:

Example 1

(1) Use a preheating furnace to preheat the original glass sheet to be chemically strengthened. The preheating temperature is 400°C and the time is 2 hours;

(2) Completely immerse the preheated glass original piece into molten salt (99.8% KNO ₃ + 0.2% NaNO ₃ ) for wet ion exchange, the temperature is 400°C, and the time is 2.5 hours;

(3) Take the original glass piece after wet ion exchange out of the molten salt without any treatment, and directly perform dry ion exchange, that is, keep it at a temperature of 400°C for 1.5 hours;

(4) The original glass sheet after dry ion exchange is annealed at an annealing temperature of 400°C and an annealing time of 2 hours to obtain the chemically strengthened glass of the present invention.

Comparative example 1

(1) Use a preheating furnace to preheat the original sheet of chemically strengthened glass; the preheating temperature is 400°C and the time is 2 hours;

(2) Immerse the preheated glass original piece into molten salt (99.8% KNO ₃ + 0.2% NaNO ₃ ) for wet ion exchange, the temperature is 400°C, and the time is 4 hours;

(3) The original glass sheet after wet ion exchange is annealed at an annealing temperature of 400°C and an annealing time of 2 hours to obtain traditional chemically strengthened glass.

The glass obtained in Example 1 and Comparative Example 1 was subjected to performance testing and warpage value testing, as shown in Table 1:

Table 1

The surface compressive stress (CS) and stress layer depth (DOL) results of the two strengthening methods are similar. Although the surface compressive stress of the chemically strengthened glass of the present invention has slightly decreased, it can fully meet the needs of downstream customers, and the 7-inch glass is warped. The warpage value has been reduced from 0.28mm to 0.15mm, that is, the warpage value has been reduced by nearly 50%, which is far superior to traditional chemically strengthened glass.

Example 2

(1) Use a preheating furnace to preheat the original glass sheet to be chemically strengthened. The preheating temperature is 400°C and the time is 2 hours;

(2) Completely immerse the preheated glass original piece into molten salt (mass percentage: 99.8% KNO ₃ + 0.2% NaNO ₃ ) for wet ion exchange, the temperature is 420°C, and the time is 3 hours;

(3) Take the original glass piece after wet ion exchange out of the molten salt without any treatment, and directly perform dry ion exchange, that is, keep it at 420°C for 1 hour;

(4) The original glass sheet after dry ion exchange is annealed at an annealing temperature of 400°C and an annealing time of 2 hours to obtain the chemically strengthened glass of the present invention.

Comparative example 2

(1) Use a preheating furnace to preheat the original sheet of chemically strengthened glass; the preheating temperature is 400°C and the time is 2 hours;

(2) Dip the preheated glass sheet into molten salt for wet ion exchange at a temperature of 420°C for 4 hours;

(3) The original glass sheet after wet ion exchange is annealed at an annealing temperature of 400°C and an annealing time of 2 hours to obtain traditional chemically strengthened glass.

The glass obtained in Example 2 and Comparative Example 2 was subjected to performance testing and warpage value testing, as shown in Table 3:

Table 2

sample Comparative example 2 Example 2 process Traditional chemical strengthening Chemical strengthening of the present invention pre-heat temperature 400℃/2hrs 400℃/2hrs Ion exchange/wet ion exchange conditions 420℃/4hrs 420℃/3hrs Dry ion exchange conditions none 420℃/1hrs Annealing temperature 400℃/2hrs 400℃/2hrs Surface compressive stress/MPa 723 642 Stress layer depth/μm 14.8 14.3 Warpage value/mm 0.35 0.18

Example 3

(1) Use a preheating furnace to preheat the original glass sheet to be chemically strengthened. The preheating temperature is 400°C and the time is 2 hours;

(2) Completely immerse the preheated glass original piece into molten salt (mass percentage: 99.8% KNO ₃ + 0.2% NaNO ₃ ) for wet ion exchange, the temperature is 380°C, and the time is 5 hours;

(3) Take the original glass piece after wet ion exchange out of the molten salt without any treatment, and directly perform dry ion exchange, that is, keep it at 380°C for 1 hour;

(4) The original glass sheet after dry ion exchange is annealed at an annealing temperature of 400°C and an annealing time of 2 hours to obtain the chemically strengthened glass of the present invention.

Comparative example 3

(1) Use a preheating furnace to preheat the original sheet of chemically strengthened glass; the preheating temperature is 400°C and the time is 2 hours;

(2) Immerse the preheated glass original sheet into molten salt for wet ion exchange at a temperature of 380°C for 6 hours;

(3) The original glass sheet after wet ion exchange is annealed at an annealing temperature of 400°C and an annealing time of 2 hours to obtain traditional chemically strengthened glass.

The glass obtained in Example 3 and Comparative Example 3 was subjected to performance testing and warpage value testing, as shown in Table 3:

table 3

sample Comparative example 3 Example 3 process Traditional chemical strengthening Chemical strengthening of the present invention pre-heat temperature 400℃/2hrs 400℃/2hrs Ion exchange/wet ion exchange conditions 380℃/6hrs 380℃/5hrs Dry ion exchange conditions none 380℃/1hrs Annealing temperature 400℃/2hrs 400℃/2hrs Surface compressive stress/MPa 742 671 Stress layer depth/μm 13.5 13.0 Warpage value/mm 0.30 0.16

Example 4

(1) Use a preheating furnace to preheat the original sheet of chemically strengthened glass; the preheating temperature is 400°C and the time is 2 hours;

(2) Immerse the preheated glass original piece into molten salt (mass percentage: 99.8% KNO ₃ + 0.2% NaNO ₃ ) for wet ion exchange, the temperature is 420°C, and the time is 4 hours;

(3) Take the original glass piece after wet ion exchange out of the molten salt without any treatment, and directly perform dry ion exchange, that is, keep it at 420°C for 1 hour;

(4) The original glass sheet after dry ion exchange is annealed at an annealing temperature of 400°C and an annealing time of 2 hours to obtain the chemically strengthened glass of the present invention.

Comparative example 4

(1) Use a preheating furnace to preheat the original sheet of chemically strengthened glass; the preheating temperature is 400°C and the time is 2 hours;

(2) Immerse the preheated glass original piece into molten salt (mass percentage: 99.8% KNO ₃ + 0.2% NaNO ₃ ) for wet ion exchange, the temperature is 420°C, and the time is 5 hours;

(3) The original glass sheet after wet ion exchange is annealed at an annealing temperature of 400°C and an annealing time of 2 hours to obtain traditional chemically strengthened glass.

The glass obtained in Example 4 and Comparative Example 4 was subjected to performance testing and warpage value testing, as shown in Table 4:

Table 4

sample Comparative example 4 Example 4 process Traditional chemical strengthening Chemical strengthening of the present invention pre-heat temperature 400℃/2hrs 400℃/2hrs Ion exchange/wet ion exchange conditions 420℃/5hrs 420℃/4hrs Dry ion exchange conditions none 420℃/1hrs Annealing temperature 400℃/2hrs 400℃/2hrs Surface compressive stress/MPa 842 801 Stress layer depth/μm 43.3 42.8 Warpage value/mm 0.25 0.13

The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can, within the technical scope disclosed in the present invention, implement the technical solutions of the present invention. Equivalent substitutions or changes of the inventive concept thereof shall be included in the protection scope of the present invention.

Claims (10)

1. A method for chemically strengthening a glass raw sheet, comprising the steps of:

s1) placing the preheated glass raw sheet into molten salt for wet ion exchange;

s2) carrying out dry ion exchange on the glass raw sheet subjected to the wet ion exchange in the step S1);

s3) annealing the glass raw sheet subjected to the dry ion exchange in the step S2).

2. The method according to claim 1, wherein the temperature of the dry ion exchange in step S2) is 360 ℃ to 450 ℃ and the time of the dry ion exchange is 0.1h to 4h.

3. The method according to claim 1, wherein the wet ion exchange in step S1) is performed at a temperature of 360 ℃ to 450 ℃ for a time of 0.5h to 8h.

4. The method according to claim 1, wherein the temperature of the wet ion exchange in step S1) is not lower than the process temperature of the dry ion exchange in step S2);

the wet ion exchange treatment time in step S1) is not less than the dry ion exchange treatment time in step S2).

5. The method according to claim 1, wherein the preheating in step S1) is performed at a temperature of 360 ℃ to 450 ℃ for a period of 1h to 3h.

6. The method according to claim 1, wherein the annealing temperature in step S3) is 360 ℃ to 450 ℃ and the annealing time is 2h to 4h.

7. A low warp value tempered glass obtained by tempering a glass raw sheet by the chemical tempering method according to any one of claims 1 to 6.

8. The low warp value strengthened glass of claim 7, wherein the composition of the raw glass sheet comprises, in mass percent of oxides:

62 to 73 percent of SiO ₂ The method comprises the steps of carrying out a first treatment on the surface of the 4% -13% of Al ₂ O ₃ The method comprises the steps of carrying out a first treatment on the surface of the 0.5 to 7.8 percent of CaO;4% -11% MgO;10 to 16 percent of Na ₂ O; and 0.5 to 3% K ₂ O；

Alternatively, the composition of the raw glass sheet comprises, in mass percent of oxides:

58% -73% of SiO ₂ The method comprises the steps of carrying out a first treatment on the surface of the 8% -18% of Al ₂ O ₃ The method comprises the steps of carrying out a first treatment on the surface of the 0.2 to 3 percent of B ₂ O ₃ The method comprises the steps of carrying out a first treatment on the surface of the 4% -11% MgO;10 to 20 percent of Na ₂ O; and 0.5 to 8% of K ₂ O。

9. A cover glass prepared from the low warp value tempered glass of claim 7 or 8.

10. A display device having the cover glass of claim 8.