WO2012093525A1

WO2012093525A1 - Method for manufacturing reinforced glass material

Info

Publication number: WO2012093525A1
Application number: PCT/JP2011/077127
Authority: WO
Inventors: 昌志田部
Original assignee: 日本電気硝子株式会社
Priority date: 2011-01-07
Filing date: 2011-11-25
Publication date: 2012-07-12
Also published as: TW201231418A; JPWO2012093525A1

Abstract

Provided is a method which can manufacture a reinforced glass material having a high degree of strength. A chemical etching step is performed for chemically etching a surface compressive stress layer of a glass material in which the compressive stress layer is formed as the surface layer.

Description

Method for producing tempered glass material

The present invention relates to a method for producing a tempered glass material. In particular, the present invention relates to a method for producing a tempered glass material having a compressive stress layer on the surface.

Conventionally, tempered glass plates have been widely used for applications such as displays and solar cells. For example, Patent Document 1 listed below describes a method for flattening by wet etching after chemically strengthening a glass substrate as a method for producing a chemically strengthened strengthened glass substrate. In the manufacturing method described in Patent Document 1, since wet etching is intended to flatten the surface of a glass substrate, wet etching is performed for a relatively long time using a relatively high concentration of hydrofluoric acid. Is called. Specifically, it is described that wet etching is performed for 10 minutes using 0.5% by mass of hydrofluoric acid and wet etching is performed for 0.5 minutes using 15% by mass of hydrofluoric acid.

JP 2000-154040 A

However, the method for producing a tempered glass substrate described in Patent Document 1 has a problem that it is difficult to produce a tempered glass substrate having sufficiently high strength.

The present invention has been made in view of such points, and an object thereof is to provide a method capable of producing a tempered glass material having high strength.

The method for producing a tempered glass material according to the present invention relates to a method for producing a tempered glass material in which a compressive stress layer is formed on the surface layer. The manufacturing method of the tempered glass material which concerns on this invention is equipped with the preparation process and the chemical etching process. A preparation process is a process of preparing the glass material in which the compressive-stress layer was formed in the surface layer. The chemical etching step is a step of chemically etching the surface layer of the compressive stress layer.

The preparing step may be a compressive stress layer forming step of forming a compressive stress layer on the surface layer of the glass material.

The compressive stress layer forming step may be a step of forming the compressive stress layer by exchanging ions in the surface layer of the glass material with ions having a larger ion radius than the ions.

In the chemical etching step, the surface layer of the compressive stress layer is preferably chemically etched so that the compressive stress reduction rate of the compressive stress layer is 5% or less.

It is preferable to perform the preparation step and the chemical etching step so that the compressive stress of the compressive stress layer after chemical etching is in the range of 300 MPa to 1200 MPa.

It is preferable to perform the compressive stress layer forming step so that the compressive stress of the compressive stress layer before chemical etching is in the range of 320 MPa to 1250 MPa.

In the chemical etching step, it is preferable that the surface layer of the compressive stress layer is chemically etched using hydrofluoric acid having an HF concentration of 0.01% by mass to 0.1% by mass as an etchant for 1 second to 22 minutes.

In the chemical etching step, chemical etching may be performed by immersing the glass material in an etching solution.

In the chemical etching step, it is preferable to perform chemical etching so that the thickness reduction due to etching is 0.1 μm to 3 μm.

According to the present invention, a method capable of producing a tempered glass material having high strength can be provided.

FIG. 1 is a schematic cross-sectional view of a glass plate according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a glass plate after a compressive stress layer forming step is performed in an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a tempered glass sheet manufactured in one embodiment of the present invention. FIG. 4 is a photomicrograph of the end face of the evaluation sample before etching. FIG. 5 is a photomicrograph of the end face of the evaluation sample 8.

Hereinafter, an example of a preferable embodiment in which the present invention is implemented will be described. However, the following embodiments are merely examples. The present invention is not limited to the following embodiments.

In the present embodiment, a method for manufacturing the tempered glass plate 1 shown in FIG. 3 will be described. However, in the present invention, the tempered glass material may not be a tempered glass plate. That is, the tempered glass material may not be plate-shaped. The tempered glass material may have, for example, a rectangular parallelepiped shape or a spherical shape.

(Glass material preparation process)
First, the glass plate 10 (refer FIG. 1) used as the base material of the tempered glass plate 1 is prepared. The glass plate 10 is typically a stress-substantially homogeneous glass plate that does not have a compressive stress layer. The glass plate 10 has a shape corresponding to the shape of the tempered glass plate 1 to be manufactured. For this reason, for example, when manufacturing a rectangular parallelepiped tempered glass material, a rectangular parallelepiped glass material may be prepared.

The glass plate 10 can form a compressive stress layer 11a described later. Specifically, for example, when the compressive stress layer 11a is formed by an ion exchange method, a glass plate containing an alkali metal ion such as sodium ion can be used as the glass plate 10, for example. When the compressive stress layer 11a is formed by a method other than the ion exchange method, for example, an alkali-free glass plate may be used as the glass plate 10.

(Compressive stress layer forming process)
Next, a compressive stress layer forming step is performed. Thereby, the preparation process which prepares the glass plate 10 in which the compressive-stress layer was formed in the surface layer 10a is performed.

In the compressive stress layer forming step, in detail, a compressive stress layer is formed on the surface layer 10 a of the glass plate 10. The method for forming the compressive stress layer is not particularly limited. For example, the compressive stress layer may be formed by an air cooling strengthening method in which the surface layer is rapidly cooled by blowing cold air to the surface layer, or the compressive stress layer may be formed by an ion exchange method. Here, the ion exchange method is a method of forming a compressive stress layer by exchanging ions in the surface layer 10a of the glass plate 10 with ions having an ion radius larger than that of the ions.

Hereinafter, in the present embodiment, an example in which a compressive stress layer is formed by exchanging sodium ions in the surface layer 10a with potassium ions will be described. In this embodiment, specifically, a plate made of silicate glass containing sodium ions is used as the glass plate 10. By immersing this glass plate 10 in a high-temperature ion exchange solution containing potassium ions such as KNO ₃ molten salt, sodium ions in the surface layer 10a are exchanged with potassium ions, and a compressive stress layer is formed. FIG. 2 shows a schematic cross-sectional view of the glass plate 11 on which the compressive stress layer 11a is formed.

The ion exchange conditions such as the type of ion exchange solution, temperature, and immersion time are the type of glass plate 10 to be used, the thickness of the compressive stress layer 11a to be formed, and the magnitude of the compressive stress of the compressive stress layer 11a to be formed. It can be set as appropriate according to the situation. The temperature of the ion exchange solution can be, for example, about 400 ° C. to 500 ° C. The immersion time of the glass plate 10 in the ion exchange solution can be, for example, about 1 hour to 10 hours.

Depending on the required characteristics of the tempered glass plate 1, the thickness of the compressive stress layer 11a can be, for example, 20 μm to 70 μm, and preferably 30 μm to 50 μm. The compressive stress of the compressive stress layer 11a is preferably 320 MPa to 1250 MPa. The compressive stress of the compressive stress layer 11a is more preferably 430 MPa to 1160 MPa. The compressive stress of the compressive stress layer 11a is more preferably 570 MPa to 850 MPa. The compressive stress of the compressive stress layer 11a is more preferably 700 MPa to 850 MPa. This is because if the compressive stress of the compressive stress layer 11a is too low, the strength of the tempered glass plate 1 may be too low. On the other hand, if the compressive stress of the compressive stress layer 11a is too high, the internal stress of the tempered glass plate 1 becomes too high and may lead to self-destruction.

In the present invention, the “thickness of the compressive stress layer” means the depth of the region where the optical waveguide effect is generated by the compressive stress of the surface layer of the tempered glass plate. Specifically, in the present invention, “thickness of compressive stress layer” and “compressive stress value” are values measured by using FSM-6000 manufactured by Orihara Seisakusho and setting photoelastic constants according to the glass material at appropriate times. .

(Chemical etching process)
Next, a chemical etching process is performed. Specifically, only the surface layer of the compressive stress layer 11a is chemically etched. Thereby, the compressive stress layer 1a shown in FIG. 3 is formed from the compressive stress layer 11a. As a result, the tempered glass plate 1 having the compressive stress layer 1a formed on the surface layer can be completed.

Thus, in this embodiment, the compressive stress layer 1a is formed by chemically etching only the surface layer of the compressive stress layer 11a. For this reason, the tempered glass board 1 which has high intensity | strength can be manufactured so that it may be supported also in the experiment example mentioned later. Although the reason why the strength is improved by chemically etching the surface layer of the compressive stress layer 11a is not clear, it is considered that the surface scratches, cracks, etc. disappear, or the surface is flattened.

From this point of view, it seems that it is preferable to form a thick compressive stress layer and to remove more parts by chemical etching. However, when the chemical etching is performed beyond the surface layer of the compressive stress layer, the strength of the tempered glass plate is lowered. Therefore, in order to manufacture the high-strength tempered glass plate 1, it is necessary to chemically etch only the surface layer of the compressive stress layer 11a as in this embodiment. The reason why the strength is reduced by chemical etching beyond the surface layer of the compressive stress layer is not clear, but chemical etching causes time on the end face of the glass plate and the compressive stress of the compressive stress layer is reduced. This is probably due to the fact that it becomes too low.

Specifically, in the chemical etching step, the compression stress layer 11a has a compressive stress reduction rate, that is, a value obtained by subtracting the compressive stress of the compressive stress layer 1a from the compressive stress of the compressive stress layer 11a. The ratio [((compressive stress of compressive stress layer 11a) − (compressive stress of compressive stress layer 1a)) / (compressive stress of compressive stress layer 11a)] to stress is 5% or less, more preferably 2% or less. It is preferable to chemically etch the surface layer of the compressive stress layer 11a within the range.

Further, it is preferable to perform the compressive stress layer forming step and the etching step so that the compressive stress of the compressive stress layer 1a is in the range of 300 MPa to 1200 MPa. More preferably, the compressive stress layer forming step and the etching step are performed so that the compressive stress of the compressive stress layer 1a is in the range of 400 MPa to 1100 MPa. More preferably, the compressive stress layer forming step and the etching step are performed so that the compressive stress of the compressive stress layer 1a is in the range of 540 MPa to 820 MPa. More preferably, the compressive stress layer forming step and the etching step are performed so that the compressive stress of the compressive stress layer 1a is in the range of 720 MPa to 820 MPa. This is because if the compressive stress of the compressive stress layer 1a is too low, the strength of the tempered glass plate 1 may be too low. On the other hand, if the compressive stress of the compressive stress layer 1a is too high, the internal stress of the tempered glass plate 1 becomes too high and may lead to self-destruction.

In order to perform the chemical etching step within the preferable range as described above, it is preferable to perform chemical etching for a relatively short period of time using an etching solution having a relatively low concentration. Specifically, chemical etching is preferably performed for 1 second to 22 minutes using hydrofluoric acid having an HF concentration of 0.01% by mass to 0.1% by mass as an etchant. More preferably, chemical etching is performed for 30 seconds to 22 minutes using hydrofluoric acid having an HF concentration of 0.03% to 0.1% by mass as an etchant.

Note that the etching solution is not limited to hydrofluoric acid. As the etching solution, for example, hydrochloric acid, sulfuric acid, nitric acid, ammonium fluoride, alkali metal hydroxide, aqueous ammonia, buffered hydrofluoric acid, and the like are preferably used.

The chemical etching may be performed, for example, by applying an etching solution to the surface of the compressive stress layer 11a, but is preferably performed by immersing the glass plate 11 in the etching solution. In the chemical etching step, it is preferable to stir the etching solution.

Further, in the chemical etching step, it is preferable to perform chemical etching so that the amount of decrease in the thickness of the compressive stress layer 11a due to etching falls within the range of 0.1 μm to 3 μm, and the amount of decrease in the thickness of the compressive stress layer 11a due to etching. More preferably, the chemical etching is performed so that the thickness is in the range of 0.5 μm to 3 μm.

(Experimental example)
Hereinafter, the present invention will be described in more detail based on specific experimental examples, but the present invention is not limited to the following experimental examples.

(Preparation of glass plate)
A glass base material made of Nippon Electric Glass Co., Ltd. made of chemically strengthened glass (material name: CX-01) having a thickness of 1 mm is cut into a size of 40 mm × 80 mm, and the end surface is mirror-polished to obtain a size of 40 mm × 80 mm × 1 mm. A glass plate was created.

(Compressive stress layer forming process)
Next, ion exchange was performed by immersing the glass plate in KNO ₃ molten salt at 440 ° C. for 6 hours. As a result, a tempered glass plate having a surface compressive stress of 665 MPa and a compressive stress layer thickness of 45 μm was obtained.

(Etching process)
Next, the tempered glass plate was etched by immersing it in hydrofluoric acid having an HF concentration of 0.06% by mass for the time shown in Table 1 below, and an evaluation sample was prepared.

(Evaluation)
The four-point bending strength of the obtained evaluation sample, the compressive stress of the compressive stress layer, and the thickness reduction amount of the compressive stress layer were measured. Moreover, the reduction rate of the compressive stress before and behind the etching process was computed from the measured value of the compressive stress of the compressive stress layer. The results are shown in Table 1 below.

Further, the end face of the sample before etching (etching time = 0 minutes) and the end face of the evaluation sample 8 with an etching time of 50 minutes were observed with a microscope. An end face of the sample before etching is shown in FIG. A photomicrograph of the end face of the evaluation sample 8 is shown in FIG. From the photographs shown in FIGS. 4 and 5, it can be seen that if the etching time is too long, the end face is damaged by the etching.

The four-point bending strength was determined by placing the evaluation sample on two cylindrical bars (R = 2 mm) arranged in parallel at an interval of 50 mm, and two cylindrical bars arranged in parallel at an interval of 25 mm ( R = 2 mm), and when the pressure is gradually applied to the upper surface of the evaluation sample, the evaluation sample is broken.

For the measurement of 4-point bending strength, Shimadzu Autograph AG-IS was used, and the 4-point bending strength was measured under a load speed of 5 mm / min.

DESCRIPTION OF SYMBOLS 1 ... Tempered glass plate 1a ... Compression stress layer 10 ... Glass plate 10a ... Surface layer 11 of a glass plate ... Glass plate 11a with a compression stress layer formed ... Compression stress layer before etching

Claims

A method for producing a tempered glass material in which a compressive stress layer is formed on a surface layer,
A preparation step of preparing a glass material having the compressive stress layer formed on a surface layer;
A chemical etching step of chemically etching the surface layer of the compressive stress layer;
A method for producing a tempered glass material.
The method for producing a tempered glass material according to claim 1, wherein the preparing step is a compressive stress layer forming step of forming the compressive stress layer on a surface layer of the glass material.
The tempered glass according to claim 2, wherein the compressive stress layer forming step is a step of forming the compressive stress layer by exchanging ions in a surface layer of the glass material with ions having an ion radius larger than the ions. A method of manufacturing the material.
The tempered glass according to any one of claims 1 to 3, wherein in the chemical etching step, a surface layer of the compressive stress layer is chemically etched so that a reduction rate of the compressive stress of the compressive stress layer is 5% or less. A method of manufacturing the material.
The tempered glass according to any one of claims 1 to 4, wherein the preparation step and the chemical etching step are performed so that a compressive stress of the compressive stress layer after the chemical etching is in a range of 300 MPa to 1200 MPa. A method of manufacturing the material.
The method for producing a tempered glass material according to claim 2, wherein the compressive stress layer forming step is performed such that the compressive stress of the compressive stress layer before the chemical etching is within a range of 320 MPa to 1250 MPa.
In the chemical etching step, the surface layer of the compressive stress layer is chemically etched for 1 second to 22 minutes using hydrofluoric acid having an HF concentration of 0.01% by mass to 0.1% by mass as an etchant. The method for producing a tempered glass material according to any one of 1 to 6.
The method for producing a tempered glass material according to any one of claims 1 to 7, wherein in the chemical etching step, the chemical etching is performed by immersing the glass material in an etching solution.
The method for producing a tempered glass material according to any one of claims 1 to 8, wherein in the chemical etching step, the chemical etching is performed so that the thickness reduction due to the etching is 0.1 μm to 3 μm.