JP4289931B2 - Method for producing chemically strengthened glass - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chemically tempered glass, particularly a chemically tempered glass useful in fields such as electronic materials, automobiles and buildings used for touch panels and the like, and a method for producing the same.
[0002]
[Prior art]
From the viewpoints of resource and energy savings and changes in social needs, tempered glass is becoming thinner and the degree of strengthening is increasing. Since the production of glass having a plate thickness of 3 mm or less, particularly 2 mm or less is difficult with the commonly used air-cooling strengthening method, the chemical strengthening method is often used for glass of 2 mm or less. In addition, chemically tempered glass generally has an advantage that it can obtain higher strength than tempered glass obtained by air cooling.
[0003]
Various methods are considered as a manufacturing method of chemically strengthened glass. For example, a method of replacing atoms of small ionic radius with atoms of large ionic radius, a method of replacing atoms of large ionic radius with atoms of small ionic radius using the viscous flow of glass, a method of utilizing difference in thermal expansion coefficient, There are many methods such as a method of crystallizing crystals and a method of combining the above methods.
[0004]
In general, many methods of replacing atoms with small ionic radii with soda-lime glass are used, and among them, many chemically strengthened glass is manufactured by the so-called immersion method, which is immersed in a chemical strengthening treatment tank. Has been. That is, a compressive stress layer is formed on the surface layer by immersing glass in a high-temperature chemical strengthening treatment solution, such as a potassium nitrate solution, and replacing sodium ions in the glass with potassium ions in potassium nitrate. In addition, as the chemical strengthening treatment liquid when the glass contains lithium, sodium nitrate or a mixed salt of sodium nitrate and potassium nitrate is frequently used.
[0005]
The reason why chemical tempered glass is widely accepted in the market is that it can be cut with tempered glass in addition to the strengthening and strengthening properties of thin glass described above. In air-cooled tempered glass, if cracks are introduced in an attempt to cut, they break apart and cannot be cut.
[0006]
From the viewpoint of known technology, for example, the use of cut glass as chemical strengthening (see, for example, Patent Document 1) is a technique for measuring surface stress, which is an important factor in cutting conditions (see, for example, Patent Document 2). Is disclosed. Steps related to chemical strengthening of hard disk drives 1) Preheating in a preheating tank (heating to 380 to 500 ° C. over about 0.5 to 2 hours)
2) Chemical strengthening treatment with molten salt solution of potassium nitrate or sodium nitrate (about 0.5-6 hours)
3) Cooling in a blast cooling tank (forced cooling to a room temperature where the in-plane temperature difference is within 5 ° C. and below the melting point of the molten salt solution with cooling air of 5 to 25 m ³ / min)
Is also described in detail (for example, see Patent Document 3). Furthermore, a method of performing both coloring and chemical strengthening using two treatment tanks is disclosed (for example, see Patent Document 4).
[0007]
[Patent Document 1]
JP 2002-160932 A [Patent Document 2]
Japanese Patent Publication No.59-37451 [Patent Document 3]
JP 2000-344550 A [Patent Document 4]
Japanese Patent Laid-Open No. 46-1329
[Problems to be solved by the invention]
Chemically tempered glass can be cut. However, even though it is possible to cut, this cutting is a very difficult technology, which is the main cause of yield reduction during production, and even after it has become a product, there is a problem of destruction due to cutting failure etc. Yes.
[0009]
For example, in a chemically strengthened thin glass used for a touch panel or the like, an attempt is made to increase productivity by taking a plurality of sheets from a large chemically strengthened glass. However, when scribing with a wheel chip type cutting machine, there are many problems that it is not divided along the scribe line at the time of division, but separated from the scribe line. For this reason, there are many cases where the merit of using multiple results is different from the original plan. In addition, there is a problem that a panel using a scribed chemically strengthened glass breaks even when it is smaller than an assumed load after being put on the market.
[0010]
Thus, in reality, it cannot be said that the cutting of chemically strengthened glass is technically established.
[0011]
That is, in Japanese Patent Application Laid-Open No. 2002-160932, it is described that the cut glass is used for chemical strengthening, but the method for cutting chemically strengthened glass is not described. Moreover, although the technique of Japanese Examined Patent Publication No. 59-37451 can know the measurement technique of the surface stress, it does not show the technique that leads to the cutting of the glass. Furthermore, the chemical strengthening method disclosed in Japanese Patent Application Laid-Open No. 2000-344550 is a case where a hard disk drive having a diameter of 60 to 100 mm is chemically strengthened, and there is no mention of cutting ability. Japanese Patent Application Laid-Open No. 46-1329 is a method in which coloring and chemical strengthening using silver are performed using two baths, and the cutting property of chemically strengthened glass is not described.
[0012]
[Means for Solving the Problems]
In the chemically tempered glass in which a compressive stress layer is formed on the glass surface layer by ion exchange, the present invention is 20 ° C. or more 50 ° C. higher than the first stage immersion liquid temperature after the first stage immersion treatment for ion exchange. This is a method for producing chemically tempered glass, which is subjected to a second immersion treatment at a high temperature of not more than ° C. and for 10 minutes or more and 60 minutes or less.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
In the chemically tempered glass in which a compressive stress layer is formed on the glass surface layer by ion exchange, the present invention is 20 ° C. or more 50 ° C. higher than the first stage immersion liquid temperature after the first stage immersion treatment for ion exchange. This is a method for producing chemically tempered glass, which is subjected to a second immersion treatment at a high temperature of not more than ° C. and for 10 minutes or more and 60 minutes or less. The reason why the second immersion liquid temperature is set to a temperature higher than the first immersion liquid temperature by 20 ° C. or more and 50 ° C. or less is that when it is less than 20 ° C., the cut ability of the chemically strengthened glass is lowered and exceeds 50 ° C. This is because the strength of the chemically strengthened glass obtained is lowered at temperature. Furthermore, there also arises a problem that the ion exchange solution is deteriorated.
[0017]
In addition, the reason for setting the time of the second dipping treatment to 10 minutes or more and 60 minutes or less is that the cutting ability of the chemically strengthened glass obtained is less than 10 minutes, and the strength of the chemically strengthened glass obtained is less than 60 minutes. It is.
[0018]
In addition, the first stage immersion treatment temperature needs to be 450 ° C. or more and 510 ° C. or less. When the temperature is lower than 450 ° C., it is difficult to improve the cutting property of the chemically strengthened glass to be obtained. When the temperature exceeds 510 ° C., there arises a problem that the strength of the chemically strengthened glass obtained becomes small.
[0019]
Furthermore, it is the chemically strengthened glass manufactured by said method. This chemically tempered glass has the characteristic of exhibiting good cutting properties at the same time while having almost the same strength as that of conventional chemically tempered glass.
[0020]
Furthermore, the chemically strengthened glass has a surface hardness of 560 to 590 kgf / cm ² . It is said that the surface hardness of soda-lime based chemically strengthened glass produced by a conventional method is 590 to 610 kgf / cm ² . However, the chemically strengthened glass according to the present invention has a surface hardness of 560 to 590 kgf / cm ² .
If it exceeds 590 kgf / cm ² , it is the same as conventional chemically tempered glass, cutting ability is poor, and sometimes it cannot be cut. Moreover, even if it can cut | disconnect, it may deviate from the desired cutting line, and it exists in the tendency for glass powder to generate | occur | produce frequently on the surface. On the other hand, chemically strengthened glass whose surface hardness is smaller than 560 kgf / cm ² tends to have low strength. The hardness may be measured by a commercially available micro hardness tester, but the load must be a small value, for example, 50 g or less. Since a load of 200 to 1000 g used for measuring the hardness of general soda-lime glass needs to be misjudged, it is necessary to be careful.
[0021]
Furthermore, it is the above chemically strengthened glass obtained by subjecting soda-lime glass having a strain point of 470 ° C. or more and 530 ° C. or less to ion exchange treatment. Since soda lime glass having a strain point lower than 470 ° C. has low chemical durability and hardness, practicality as chemically tempered glass is greatly reduced. On the other hand, soda-lime glass having a strain point higher than 530 ° C. decreases the cutting ability of the glass and also decreases the chemical strengthening property. Glasses other than soda-lime glass are expensive because of poor productivity, so their practicality is small even if they have cutting properties and strength.
[0022]
The chemically tempered glass of the present invention has the characteristics that it has substantially the same strength as conventional chemically tempered glass and has a cutting property. This is because, unlike conventional chemically strengthened glass, the stress pattern does not depend only on Fick's law.
[0023]
【Example】
Hereinafter, description will be made based on examples.
Example 1
A 0.7 mm thick soda-lime float glass was immersed in a molten salt of potassium nitrate at 460 ° C. for 10 hours and subjected to the first chemical strengthening (ion exchange) treatment, followed by a second 60 minutes at an immersion liquid temperature of 510 ° C. The ion exchange treatment was performed. Immediately thereafter, the chemically tempered glass was moved to a cooling bath set at 500 ° C., and further held therein for 60 minutes. After that, the glass was cooled at a usual cooling rate (about 10 ° C./min) to obtain a predetermined chemically strengthened glass product. The chemically hardened glass product had a surface hardness of 565 kgf / cm ² .
[0024]
When this chemically strengthened glass was subjected to a scribe (load weight: 2 kg) and a split test in accordance with a general cutting operation using a commercially available carbide wheel tip, it could be cut without any problem.
A predetermined chemically strengthened glass was obtained.
[0025]
(Example 2)
A soda-lime float glass having a thickness of 0.55 mm is immersed in molten potassium nitrate at 470 ° C. for 4 hours and subjected to a first chemical strengthening (ion exchange) treatment, followed by a second treatment for 20 minutes at an immersion liquid temperature of 510 ° C. The ion exchange treatment was performed. Immediately thereafter, the chemically tempered glass was moved to a cooling bath set at 500 ° C., and further held therein for 20 minutes. After that, the glass was cooled at a usual cooling rate (about 10 ° C./min) to obtain a predetermined chemically strengthened glass product. The chemically hardened glass product had a surface hardness of 580 kgf / cm ² .
[0026]
When this chemically strengthened glass was subjected to a scribe (load weight: 2 kg) and a split test in accordance with a general cutting operation using a commercially available carbide wheel tip, it could be cut without any problem.
[0027]
(Example 3)
A 1.1 mm thick soda-lime float glass is immersed in molten potassium nitrate at 505 ° C. for 1 hour to perform a first chemical strengthening (ion exchange) treatment, followed by a second treatment for 10 minutes at an immersion liquid temperature of 525 ° C. The ion exchange treatment was performed. Immediately thereafter, the chemically tempered glass was moved to a cooling bath set at 500 ° C., and further maintained therein for 3 minutes. After that, the glass was cooled at a usual cooling rate (about 10 ° C./min) to obtain a predetermined chemically strengthened glass product. The surface hardness of this chemically strengthened glass product was 585 kgf / cm ² .
[0028]
This chemically tempered glass was scribed (loading weight: 2kg) and split test in accordance with general cutting work using commercially available carbide wheel tips. It was possible to cut without problems.
[0029]
(Comparative Example 1)
A soda-lime float glass having a thickness of 0.7 mm was immersed in a molten potassium nitrate salt at 460 ° C. for 10 hours for chemical strengthening (ion exchange) treatment, and immediately put into a cooling step to produce chemically strengthened glass.
[0030]
When this chemically tempered glass was scribed using a commercially available carbide wheel tip and cut, a slip was noticeable. Therefore, when the cutting pressure was increased and examined, a lot of linear glass powder was generated from the scribe line and could not be used as a chemically strengthened glass product. In some cases, it could not be divided along the scribe line.
[0031]
(Comparative Example 2)
A soda-lime float glass having a thickness of 0.55 mm was immersed in a potassium nitrate molten salt at 470 ° C. for 4 hours for chemical strengthening (ion exchange) treatment, and immediately put into a cooling step to produce chemically strengthened glass.
[0032]
When this chemically tempered glass was scribed using a commercially available carbide wheel tip and cut, a slip was noticeable. Therefore, when the cutting pressure was increased and examined, this chemically strengthened glass was broken.
[0033]
(Comparative Example 3)
After a 1.1 mm thick aluminoboric acid-based glass was immersed in a molten salt of potassium nitrate at 460 ° C. for 10 hours for chemical strengthening (ion exchange) treatment, it was immediately put into a cooling step to produce chemically strengthened glass.
[0034]
When this chemically tempered glass was scribed using a commercially available carbide wheel tip and cut, a slip was noticeable. Then, although it examined by making cutting pressure strong, this chemically strengthened glass was not able to be cut | disconnected along a scribe line.
[0035]
As shown from the above results, chemically tempered glass that can be easily cut was obtained by adding the process of the present invention after the ion exchange process.
[0036]
【The invention's effect】
Up to now, it has become possible to stably cut chemically strengthened glass, which has been considered difficult.

Claims (2)

  In the method for producing chemically strengthened glass in which a compressive stress layer is formed on the glass surface layer by ion exchange, after immersion treatment for ion exchange, the temperature is higher than the immersion liquid by 20 ° C. or more and 50 ° C. or less for 10 minutes or more and 60 minutes. A method for producing chemically tempered glass, characterized by performing a second immersion treatment for a minute or less.   The method for producing chemically strengthened glass according to claim 1, wherein the temperature of the first stage immersion liquid is 450 ° C. or more and 510 ° C. or less.