JP2018002552A - Manufacturing method of reinforced glass and reinforced glass manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a reinforced glass and a reinforced glass manufacturing device capable of stably manufacturing a reinforced glass sheet having high strength.SOLUTION: There is provided a manufacturing method of a reinforced glass for exchanging ions of a reinforced glass surface layer, having a process for making an ion exchange inhibition membrane inhibiting ion exchange on at least a part of a surface of a glass and a process for exchanging ions by contacting molten salt with a surface of the glass on which the ion exchange inhibition membrane is made, the molten salt contains a first ion which is introduced to a glass surface layer in ion exchange and a second ion which is an ion of same group element as the first ion and has smaller ion radius than that of the first ion and content of the second ion in the molten salt is 4500 mass.ppm or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing tempered glass and an apparatus for producing tempered glass, and more specifically to a method for producing tempered glass and an apparatus for producing tempered glass for chemically strengthening a glass plate by an ion exchange method.

  Conventionally, a tempered glass plate that has been chemically strengthened as a cover glass has been used for touch panel displays mounted on electronic devices such as smartphones and tablet PCs.

  Such a tempered glass plate is generally produced by chemically treating a glass plate containing an alkali metal as a composition with a tempering solution to form a compressive stress layer on the surface. Since such a tempered glass plate has a compressive stress layer on the main surface, the impact resistance to the main surface is improved. On the other hand, a tensile stress layer corresponding to the compressive stress layer on the main surface is formed inside such a tempered glass plate. If this tensile stress becomes excessively large, cracks on the end face are caused due to this. Damage due to progress (so-called self-destruction) is likely to occur. Further, when the compressive stress layer on the surface of the glass plate is formed to be shallow as a whole in order to reduce such tensile stress, there is a problem that sufficient impact resistance cannot be obtained at the end face.

  In order to solve the above problems, a technique has been developed to appropriately set the balance of the compressive stress between the main surface and the end face of the tempered glass sheet and reduce the internal tensile stress within an appropriate range. For example, in Patent Document 1, by forming a film that suppresses ion exchange in advance on the main surface and suppressing the progress of chemical strengthening compared to the end surface, the compressive stress layer on the end surface is relatively deeper than the main surface. A technique for forming and improving the strength at the end face is disclosed.

JP 2014-208570 A

  The molten salt used for ion exchange of tempered glass gradually changes in liquid quality by repeated use. Therefore, when a membrane that suppresses ion exchange is formed as in the technique of Cited Document 1, depending on the quality of the reinforcing liquid used for ion exchange, chemical strengthening is excessive at the location where the membrane that suppresses ion exchange is formed. In some cases, a sufficient compressive stress layer could not be obtained. That is, there is still room for improvement in the method for stably producing tempered glass having high strength.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a tempered glass manufacturing method and a tempered glass manufacturing apparatus capable of stably manufacturing a tempered glass plate having high strength. And

  The method for producing tempered glass of the present invention is a method for producing tempered glass for exchanging ions on the surface layer of a tempered glass, and an ion exchange suppressing film for suppressing ion exchange is formed on at least a part of the surface of the glass. A step of bringing the molten salt into contact with the surface of the glass on which the ion exchange suppressing film has been formed and exchanging ions, wherein the molten salt includes first ions introduced into the glass surface layer in the exchange of ions; The second ion is a first ion and a second element ion having a smaller ion radius than the first ion, and the content of the second ion in the molten salt is 4500 mass ppm or more.

  In the method for producing tempered glass of the present invention, the first ion is potassium ion, the second ion is sodium ion, and the content of sodium ion in the molten salt is preferably 5000 to 7900 mass ppm or more. .

The method of manufacturing a tempered glass of the present invention, the ion-exchange suppression layer has a composition containing SiO ₂ 90% or more preferably has a thickness of 5～2000Nm.

The method of manufacturing a tempered glass of the present invention, the reinforcing glass, in weight percent as a glass _{composition, SiO 2 45~75%, Al 2} O 3 1~30%, Na 2 O 0~20%, K 2 O 0 A glass plate containing ˜20%, an ion exchange suppressing film is formed only on the main surface of the reinforcing glass, and the glass with film is immersed in a molten salt at 350 to 500 ° C. for 0.1 to 150 hours for ions. It is preferable to perform the exchange.

  The tempered glass manufacturing apparatus of the present invention is a tempered glass manufacturing apparatus provided with a salt bath containing molten salt for exchanging ions on the glass surface layer, and the molten salt is introduced into the glass surface layer in the exchange of ions. The first ion and a second ion that is an ion of the same family element as the first ion and has an ion radius smaller than that of the first ion, and the content of the second ion in the molten salt is 4500 mass ppm or more. And

  The tempered glass manufacturing apparatus includes a film forming apparatus that forms an ion exchange suppressing film that suppresses permeation of ions on at least a part of the surface of the glass, and a support apparatus that supports the formed glass. It is preferable that the glass is supported so as to be immersed in the salt bath.

  According to the present invention, by appropriately adjusting the molten salt used for the chemical strengthening of the glass, the ion exchange is not excessively suppressed at the location where the ion exchange suppressing film is formed, and has a high strength. Can be manufactured stably.

The figure which shows an example of the manufacturing method of the tempered glass of this invention

  Hereinafter, the manufacturing method of the tempered glass of embodiment of this invention is demonstrated. FIG. 1 is a diagram showing an example of a method for producing tempered glass of the present invention.

  First, the preparatory process shown in FIG. The preparation step is a step of preparing the reinforcing glass G1. The tempering glass G1 is a glass that can be tempered using an ion exchange method.

Reinforced glass G1 is the mass% as a glass _{composition, SiO 2 45~75%, Al 2} O 3 1~30%, Na 2 O 0~20%, preferably contains K 2 O 0 to 20% . If the glass composition range is regulated as described above, it becomes easy to achieve both ion exchange performance and devitrification resistance at a high level.

  The thickness of the reinforcing glass G1 is, for example, 1.5 mm or less, preferably 1.3 mm or less, 1.1 mm or less, 1.0 mm or less, 0.8 mm or less, 0.7 mm or less, 0.6 mm or less. 0.5 mm or less, 0.4 mm or less, 0.3 mm or less, 0.2 mm or less, especially 0. 1 mm or less. As the plate thickness of the tempered glass substrate is smaller, the tempered glass substrate can be made lighter, and as a result, the device can be made thinner and lighter. In consideration of productivity and the like, the glass thickness of the tempering glass G1 is preferably 0.01 mm or more.

  The dimensions of the main surface of the tempering glass G1 are, for example, 480 × 320 mm to 3350 × 3950 mm.

  It is preferable that the glass G1 for reinforcement | strengthening is plate-shaped using the overflow downdraw method, and the main surface S is not grind | polished. The strengthened glass G1 formed in this way can provide a strengthened glass plate having high surface quality at low cost. In addition, you may select arbitrarily the shaping | molding method and processing state of the glass G1 for reinforcement | strengthening. For example, the reinforcing glass G1 may be formed using a float process, and the main surface S and the end surface E may be polished.

  Next, after the preparatory step, the film forming step shown in FIG. The film forming step is a step of obtaining the film-coated glass G2 by forming the ion exchange suppressing film M on at least a part of the surface of the reinforcing glass G1. The ion exchange suppression membrane M is a membrane layer that suppresses permeation of ions when ion exchange is performed on the surface of the reinforcing glass G1 in the strengthening step described later. In other words, the ion exchange suppression membrane M allows the ions to be exchanged to permeate appropriately, and does not completely block the permeation of the ions. In the present embodiment, in the glass with film G2, the ion exchange suppression film M is formed only on the front and back main surfaces S, and the end face E is exposed.

As a material of the ion exchange suppressing film M, any material may be used as long as the permeation of ions to be ion exchanged can be suppressed. When the ion to be exchanged is an alkali metal ion, the ion exchange suppressing film M is, for example, a film made of a metal oxide, metal nitride, metal carbide, metal oxynitride, metal oxycarbide, metal carbonitride, or the like. Preferably there is. More specifically, examples of the material of the ion exchange suppressing film M include SiO ₂ , Al ₂ O ₃ , SiN, SiC, Al ₂ O ₃ , AlN, ZrO ₂ , TiO ₂ , Ta ₂ O ₅ , and Nb ₂ O. ₅ , a film containing one or more of HfO ₂ and SnO ₂ can be used.

In particular, it is preferable to use SiO ₂ as a main component of the ion exchange suppressing film M because the ion exchange suppressing film M can be easily formed at low cost and can function as an antireflection film. The ion exchange suppression film M may be a film made of only SiO ₂ . Specifically, the ion exchange suppressing membrane M may have a composition containing 90% or more, preferably 99% or more of SiO ₂ by mass%.

  The thickness of the ion exchange suppression membrane M is preferably 5 to 2000 nm, more preferably 50 to 1000 nm, still more preferably 100 to 600 nm, and most preferably 150 to 500 nm. By setting the thickness of the ion exchange suppression membrane M within the above range, ion exchange can be suitably performed without permeating ions or blocking ions too much.

  The film formation method of the ion exchange suppression film M is a PVD method (physical vapor deposition method) such as a sputtering method or a vacuum evaporation method, a CVD method (chemical vapor deposition method) such as a thermal CVD method or a plasma CVD method, or dip coating. A wet coating method such as a method or a slit coating method can be used. In particular, a sputtering method and a dip coating method are preferable. When the sputtering method is used, the ion exchange suppressing film M can be easily and uniformly formed. The position where the ion exchange suppression film M is formed may be set by an arbitrary method. For example, the film formation may be performed in a state where a mask is previously applied to a non-film formation portion (end surface E in the present embodiment).

  Next, after the film forming step, the strengthening step shown in FIG. The tempering step is a step of chemically strengthening the film-coated glass G2 by an ion exchange method to obtain a film-coated tempered glass G3. Specifically, ion exchange is performed by immersing the film-coated glass G2 in a molten salt T containing alkali metal ions.

  In the present embodiment, the molten salt T includes potassium ions (first ions) introduced into the glass surface layer in the exchange of ions, and sodium ions (second ions) that are ions of the same family elements as the potassium ions and have a smaller ion radius than the potassium ions. Ion). The content of sodium ions (second ions) in the molten salt is 4500 mass ppm or more, preferably 5000 to 25000 ppm, more preferably 5500 to 10000, and most preferably 6000 to 7900 ppm.

  By setting the content of sodium ions contained in the molten salt T within the above range, ions to be ion exchanged, that is, potassium ions introduced into the strengthening glass G1 and sodium ions derived from the strengthening glass G1 are ionized. The exchange suppression membrane M can be permeated appropriately. Therefore, it is possible to appropriately perform ion exchange at the film formation location. The molten salt T in this embodiment is, for example, a mixed salt of potassium nitrate molten salt and sodium nitrate molten salt.

  In this invention, it is preferable to implement the adjustment process which adjusts content of the sodium ion (2nd ion) in molten salt T in the said range before or after a reinforcement | strengthening process. In the adjustment step, for example, the molten salt T can be adjusted by adding a potassium nitrate molten salt, a sodium nitrate molten salt, or the like.

  Although the temperature of the molten salt in a reinforcement | strengthening process may be determined arbitrarily, it is 350-500 degreeC, for example, Preferably it is 370-480 degreeC. The time for immersing the film-coated glass G2 in the molten salt T may be arbitrarily determined, and is, for example, 0.1 to 150 hours, preferably 0.5 to 50 hours.

  In the tempering step, sodium ions on the surface of the film-coated glass G2 and potassium ions in the molten salt T are exchanged to obtain a film-reinforced glass G3 having a compressive stress layer C on the surface. Here, in the surface of the film-coated glass G2, the ion exchange suppression is suppressed in the portion (main surface S) where the ion exchange suppression film M is provided compared to the exposed portion E where the surface of the reinforcing glass G1 is exposed. Therefore, the depth of the compressive stress layer is reduced. In other words, in the exposed portion E, the ion exchange can proceed more easily than the portion where the ion exchange suppressing film M is provided, and the depth of the compressive stress layer is increased. In this way, the tempered glass with film G3 has a deeper compressive stress layer at the end surface than the main surface, and therefore has a lower internal tensile stress than the tempered glass strengthened entirely, and at the end portion. High impact resistance. Therefore, the damage resulting from the progress of the crack from the end can be suitably suppressed.

  In addition, when the above-described inorganic composition material is adopted as the ion exchange suppressing film M, it is melted compared to a conventional organic protective film or the like even when immersed in the molten salt T with the film provided. It is difficult to deteriorate the salt T.

  Treatment conditions such as treatment temperature and immersion time in the tempering step may be appropriately determined according to the characteristics required for the tempered glass with film G3. The processing conditions are preferably adjusted so that the depth of the compressive stress layer on the main surface S of the tempered glass G3 with film is smaller than the depth of the compressive stress layer on the exposed portion E.

  Since the ion exchange suppression film M also functions as a protective coating or an antireflection film for electronic devices, the tempered glass with film G3 can be used as a product as it is, but depending on the application, the ion exchange suppression film M can be used. It may be peeled off. In the peeling step shown in FIG. 1 (d), the ion exchange inhibiting film M is peeled from the tempered glass G3 with film to obtain a tempered glass plate G4.

Specifically, the ion exchange suppressing film M is removed by attaching an etching solution to the film-reinforced glass G3. When the ion exchange suppressing film M is a film containing SiO ₂ , for example, a solution containing fluorine, TMAH, EDP, KOH or the like can be used as an etching solution, and a hydrofluoric acid solution is particularly preferably used as an etching solution. . In addition, the peeling method of the ion exchange suppression film | membrane M is not restricted above, You may use a well-known method as a method of removing the film | membrane provided in the glass plate, for example, the ion exchange suppression film | membrane M by mechanical processing, such as grinding | polishing. It may be removed.

  In the peeling step, only the ion exchange suppression film M on one main surface side may be removed, or the ion exchange suppression film M on both main surfaces may be removed. In addition, the ion exchange suppression membrane M may be partially removed from each main surface, or all of the ion exchange suppression membrane M may be removed.

  When removing the ion exchange suppressing film M on one side or partially, the etching liquid is partially adhered using a spray, roll, brush, etc., or the masked tempered glass G3 is partially masked to etch the liquid. It is possible to remove the film by immersing the film in the film.

  In the case of removing all of the ion exchange suppressing film M, it is preferable to immerse the entire film-reinforced glass G3 in an etching solution. Thus, if the whole tempered glass G3 with a film | membrane is immersed in etching liquid, the tempered glass board G4 which reduced the microcrack which causes damage and improved the intensity | strength will be easy.

  As described above, according to the method for producing tempered glass according to the embodiment of the present invention, the tempered glass G3 and the tempered glass G4 with less damage from the end face can be efficiently produced.

  In addition, the material of the ion exchange suppression film | membrane M mentioned above is an example, and as long as it is a film | membrane which can suppress permeation | transmission of the ion exchanged in a reinforcement | strengthening process, you may use arbitrary materials.

  In addition, before and after the arbitrary steps described above, a processing step for performing any one of cutting processing, end surface processing, and drilling processing may be provided. In addition, before and after the arbitrary steps described above, the glass plate may be appropriately washed and dried.

  Moreover, although the said embodiment demonstrated as an example the case where the molten salt T contains a sodium ion as a 2nd ion, the molten salt T may contain the lithium ion as a 2nd ion. Further, the present invention is not limited to alkali metal ions, but can be applied to ions of other arbitrary groups used for ion exchange of glass.

The manufacturing method of the tempered glass mentioned above can be implemented using the tempered glass manufacturing apparatus provided with the salt bath X which accommodated the said molten salt T. FIG. The salt tub X is, for example, a tank made of a metal casing having an upper opening, and has an internal space filled with the molten salt T. The said tempered glass manufacturing apparatus is further provided with the support apparatus (not shown) which is comprised by the shape and dimension which can be accommodated in the salt tub X, and can support the glass G2 with a film | membrane. The support device is a jig constituted by a metal frame such as stainless steel, for example. By immersing in the molten salt T in the salt bath X in a state where the glass G2 with film is supported by the support device, the treatment of the strengthening step can be performed. Note that the tempered glass manufacturing apparatus may further include a film forming apparatus (not shown) that performs the film forming process. As the film forming apparatus, a known sputter film forming apparatus or the like can be used.

  Hereinafter, based on an Example, this invention is demonstrated in detail.

  In Table 1, Nos. 1 to 4 show examples of the present invention, and Nos. 5 to 8 show comparative examples.

Each sample in Table 1 and Table 2 was produced as follows. First, the glass composition contains glass so as to contain 61.6% SiO ₂ , 19.6% Al ₂ O ₃ , 0.8% B ₂ O ₃ , 16% Na ₂ O, and 2% K ₂ O by mass%. The raw materials were prepared and melted, and formed into a plate shape using an overflow downdraw method to obtain a plurality of tempered glasses having a thickness of 0.7 mm. Next, a film having a film thickness shown in Table 1 and having a film thickness of 100% SiO ₂ as an ion exchange suppressing film was formed on both main surfaces of the glass for strengthening by sputtering, and then 20 × 50 mm in size by scribe cleaving. The glass with a film | membrane which has an exposed part in the end surface was obtained by cutting out into rectangular shape. In addition, about the sample of No. 7 and 8, the said cutting | disconnection was performed without performing the said film-forming. Next, the obtained film-coated glass was immersed in a mixed molten salt of potassium nitrate and sodium nitrate at 430 ° C. containing sodium ions in the amount shown in Table 1 for 5 hours, chemically reinforced, washed with pure water and naturally dried. No. of description. The tempered glass board sample of 1-8 was obtained.

  The following measurement test was performed on each glass sample obtained as described above.

  The main surface compressive stress value CS, the main surface stress depth DOL, and the internal tensile stress CT were measured with a stress meter (FSM-6000LE and FsmXP manufactured by Orihara Seisakusho).

  The falling ball test was carried out by placing the edge of a tempered glass plate sample having a size of 65 mm in length and 130 mm in width created in the same manner as described above on a frame-shaped jig having an open center portion made of paper bakelite. A steel ball was dropped on the center of the glass, and the height at which it was damaged by a single collision was recorded. Specifically, from a height of 15 cm, the steel ball is repeatedly dropped while raising the drop position in 5 cm increments, the height at which the tempered glass is broken is recorded, the height of the broken glass is Weibull plotted, and the breakage probability is 63 % Height was obtained as an average value. In addition, each sample grind | polished the end surface beforehand with the 800th grindstone. Further, the tempered glass of each sample was placed on a jig so that the margin of each side was 5 mm.

  As shown in Table 1, since the sample Nos. 5 and 6 as comparative examples have a low sodium ion content in the molten salt, the ion exchange is excessively suppressed by the ion exchange suppression membrane, and an appropriate surface compressive stress value CS is obtained. And the surface compressive stress depth DOL could not be obtained. On the other hand, each sample of the example has a compressive stress layer having an appropriate surface compressive stress value and surface compressive stress depth on the surface on which the ion exchange suppressing film is formed as a result of appropriately adjusting the content of sodium ions. Been formed.

  Moreover, as a result of the chemical strengthening of the samples of Comparative Examples No. 7 and 8 without forming an ion exchange suppressing film, the balance between the compressive stress on the surface and the end face is not suitable, the internal tensile stress CT is high, and self-destructing is easy. It was glass. On the other hand, each sample of the example was a glass that was not easily self-breaking because the balance between the compressive stresses on the surface and the end face was suitably set and the internal tensile stress CT was suppressed.

  The tempered glass plate and the manufacturing method thereof of the present invention are useful as a glass substrate used for a touch panel display and the like, a manufacturing method thereof, and the like.

G1 Glass for strengthening G2 Glass with film G3 Tempered glass with film G4 Tempered glass plate M Ion exchange inhibiting film T Molten salt X Salt bath

Claims (6)

A method for producing tempered glass for exchanging ions on the surface of a tempered glass,
Forming a film-reinforced glass by forming an ion exchange suppressing film that suppresses the exchange of ions on at least a part of the surface of the reinforcing glass; and
A step of bringing the molten glass into contact with the molten salt and exchanging the ions,
The molten salt is
A first ion introduced into the tempered glass surface layer in the exchange of the ions;
A second ion that is an ion of the same element as the first ion and has an ion radius smaller than that of the first ion,
Content of said 2nd ion in the said molten salt is 4500 mass ppm or more, The manufacturing method of tempered glass characterized by the above-mentioned. The first ion is a potassium ion;
The second ion is a sodium ion;
2. The method for producing tempered glass according to claim 1, wherein a content of the sodium ion in the molten salt is 5000 to 7900 mass ppm or more. The ion-exchange suppression film has a composition containing SiO ₂ 90% or more, wherein the thickness is 5～2000Nm, method for producing a tempered glass according to claim 1 or 2. The reinforcing glass, in weight percent as a glass _{composition, SiO 2 45~75%, Al 2} O 3 1~30%, Na 2 O 0~20%, a glass plate containing K 2 O 0 to 20% Yes,
Forming the ion exchange suppressing film only on the main surface of the strengthening glass,
The method for producing tempered glass according to any one of claims 1 to 3, wherein the ion exchange is performed by immersing the film-coated glass in the molten salt at 350 to 500 ° C for 0.1 to 150 hours. A tempered glass manufacturing apparatus including a salt bath containing a molten salt for exchanging ions on a tempered glass surface,
The molten salt is
A first ion introduced into the tempered glass surface layer in the exchange of the ions;
A second ion that is an ion of the same element as the first ion and has an ion radius smaller than that of the first ion,
The tempered glass manufacturing apparatus, wherein the content of the second ion in the molten salt is 4500 mass ppm or more. A film forming apparatus for forming an ion exchange suppressing film for suppressing permeation of the ions on at least a part of the surface of the strengthening glass;
A support device for supporting the tempered glass thus formed;
The tempered glass manufacturing apparatus according to claim 6, wherein the support device is configured to be dipped in the salt bath in a state where the tempering glass is supported.