JP7019941B2 - Manufacturing method of tempered glass and manufacturing method of tempered glass - Google Patents

Description

The present invention relates to a method for producing tempered glass and a method for producing tempered glass, and more particularly to a method for producing tempered glass and a method for producing tempered glass, which contribute to improving scratch resistance.

Currently, smartphones are widely used. Tempered glass that has been ion-exchanged is used for the cover glass of smartphones. Tempered glass is suitable for this application because it has higher mechanical strength than unreinforced glass (see Patent Document 1 and Non-Patent Document 1).

In addition to high mechanical strength, tempered glass is required to have properties such as high scratch resistance, light weight, and low cost. Furthermore, in smartphone applications, there is an increasing demand for weight reduction, that is, thinning.

However, if the tempered glass is made thinner, the internal tensile stress becomes excessive, so that when the tempered glass is broken, the glass pieces may scatter or the tempered glass may self-destruct. Therefore, when the tempered glass is made thinner, it is necessary to reduce the compressive stress value and the stress depth of the compressive stress layer, and as a result, the mechanical strength tends to decrease.

Japanese Unexamined Patent Publication No. 2006-83045

Tetsuro Izumitani et al., "New Glass and Its Physical Properties", First Edition, Keiei System Research Institute, Inc., August 20, 1984, p. 451-498

Therefore, it is effective to maintain the mechanical strength by reducing the surface scratches of the tempered glass (tempered glass) as much as possible.

Conventionally, as a means for reducing surface scratches, it has been proposed to form a protective film on the reinforcing glass. However, the formation and removal of the protective film are costly, and it becomes impossible to meet the demand for cost reduction.

Therefore, the present invention is to devise a method for manufacturing a reinforcing glass that can maintain mechanical strength without causing an increase in cost.

As a result of various studies, the present inventor has found that the above technical problems can be solved by placing the reinforcing glass in a moist environment, and proposes the present invention. That is, the method for producing a reinforcing glass of the present invention has a glass composition of SiO ₂ 40 to 75%, Al ₂ O ₃₀ to 30%, Na ₂ O 5 to 25%, and K ₂ O 0 to 20% by mass. A blending step of blending a glass raw material to obtain a glass batch, a melting step of melting the glass batch to obtain molten glass, and a molten glass into a predetermined shape so that a strengthening glass containing 10% can be obtained. It is characterized by comprising a molding step of forming to obtain a tempering glass and a contacting step of bringing the tempering glass into contact with a moist atmosphere having a humidity of 60 to 99%.

The method for producing a tempering glass of the present invention includes a contacting step of bringing the tempering glass having the above glass composition into contact with a moist atmosphere having a humidity of 60 to 99%. As a result, the crack occurrence rate of the strengthening glass is reduced, and surface scratches are less likely to occur on the strengthening glass.

Secondly, in the method for producing a tempering glass of the present invention, when the temperature in a moist atmosphere is T (° C.) and the contact time of the tempering glass is t (hours), -14.0 ≦ 0.5 ×. It is preferable to satisfy the relationship of ln (t) -5021 / (T + 273) ≦ −7.5.

Thirdly, in the method for producing the reinforcing glass of the present invention, it is preferable to form the molten glass into a flat plate shape.

Fourth, the method for producing the tempering glass of the present invention preferably includes a slow cooling step of slowly cooling the tempering glass after the molding step and before the contacting step.

Fifth, in the method for producing tempered glass of the present invention, in the method for producing tempered glass in which the tempered glass is ion-exchanged to obtain tempered glass, the tempered glass is produced by the above-mentioned method for producing tempered glass. It is preferable to do so.

Sixth, in the method for producing tempered glass of the present invention, it is preferable to use tempered glass as the cover glass of the touch panel display.

Seventh, in the method for producing tempered glass of the present invention, it is preferable to use tempered glass as a substrate or a cover glass of a solar cell.

Eighth, in the method for producing tempered glass of the present invention, it is preferable to use tempered glass as an exterior member.

In the method for producing a reinforcing glass of the present invention, a glass raw material as an introduction source of each component is prepared and mixed to prepare a glass batch batch. If necessary, a glass cullet may be used as a glass raw material. The glass cullet is glass scrap discharged in the glass manufacturing process or the like. The method for mixing the glass raw materials is not particularly limited, but may be appropriately selected depending on the mass to be mixed at one time and the type of the glass raw materials. For example, a method of mixing using a bread type mixer, a rotary mixer, or the like can be mentioned.

In the method for producing a reinforcing glass of the present invention, the glass composition is SiO ₂ 40 to 75%, Al ₂ O ₃₀ to 30%, Na ₂ O 5 to 25%, K ₂ O 0 to 10% by mass. The glass raw material is prepared so as to obtain a strengthening glass containing. The reasons for limiting the content range of each component as described above are shown below. In the description of the content range of each component, the% indication indicates mass% unless otherwise specified.

SiO ₂ is a component that forms a network of glass. Suitable lower limit range of SiO ₂ is 40% or more, 45% or more, 46% or more, 47% or more, 47.5% or more, 50% or more, 55% or more, 56% or more, 57% or more, 58% or more, It is 59% or more, particularly 60% or more, and suitable upper limit ranges of SiO ₂ are 75% or less, 72% or less, 71% or less, and particularly 70% or less. If the content of SiO ₂ is too small, it becomes difficult to vitrify, the coefficient of thermal expansion becomes unreasonably high, and the thermal impact resistance tends to decrease. On the other hand, if the content of SiO ₂ is too large, the meltability, formability, thermal workability, etc. tend to decrease, and the coefficient of thermal expansion becomes unreasonably low, making it difficult to match the coefficient of thermal expansion of the peripheral material. ..

Al ₂ O ₃ is a component that enhances the ion exchange performance, and is a component that enhances the strain point and Young's modulus. Suitable lower limit range of Al ₂ O ₃ is 0% or more, 1% or more, 3% or more, 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, 10% or more, 11% or more, 12% or more, 13% or more, 14% or more, 15% or more, 16% or more, 17% or more, particularly 18% or more, and suitable upper limit ranges of Al ₂ O ₃ are 30% or less, 29% or less, 28. % Or less, 27% or less, 26% or less, 25% or less, 24% or less, especially 23% or less. If the content of Al ₂ O ₃ is too small, there is a risk that the ion exchange performance cannot be fully exhibited. In addition, the crack occurrence rate may increase. On the other hand, if the content of Al ₂ O ₃ is too large, devitrified crystals are likely to precipitate on the glass, and it becomes difficult to form a flat plate shape by an overflow down draw method or the like. In particular, when an alumina molded body is used and molded into a flat plate shape by the overflow downdraw method, devitrified crystals of spinel are likely to precipitate at the interface with the alumina molded body. In addition, the coefficient of thermal expansion becomes unreasonably low, and it becomes difficult to match the coefficient of thermal expansion of peripheral materials. In addition, the acid resistance is lowered, which makes it difficult to apply to the acid treatment process. Further, the high-temperature viscosity becomes high, and the meltability, heat workability, and the like tend to decrease.

Na ₂ O is an ion exchange component, and is a component that effectively exhibits the effect of reducing the crack generation rate when exposed to a moist atmosphere. Further, Na ₂ O is a component that lowers the high-temperature viscosity and enhances meltability, moldability, heat processability, etc., and is also a component that improves the reactivity with the refractory of the molded product. Suitable lower limit ranges of Na ₂ O are 5% or more, 7% or more, 7.0% or more, 8% or more, 9% or more, 10% or more, 11% or more, particularly 12% or more, and Na ₂ O. Suitable upper limit ranges are 25% or less, 23% or less, 21% or less, 20% or less, 19.5% or less, 19% or less, 18.5% or less, 18% or less, 17.5% or less, especially 17%. It is as follows. If the content of Na ₂ O is too small, it becomes difficult to enjoy the above effects. On the other hand, if the content of Na ₂ O is too large, the coefficient of thermal expansion becomes unreasonably high, the thermal impact resistance is lowered, and it becomes difficult to match the coefficient of thermal expansion of the peripheral material. In addition, the strain point may be lowered too much, or the component balance of the glass composition may be lost, and the devitrification resistance may be lowered.

K ₂ O is a component that promotes ion exchange, and is a component that easily increases the stress depth among alkali metal oxides. In addition, it is a component that lowers the high-temperature viscosity and enhances meltability, moldability, heat processability, and the like. Furthermore, it is also a component that improves devitrification resistance. Suitable upper limit ranges of K ₂ O are 10% or less, 9% or less, 8% or less, 7% or less, particularly 6% or less, and suitable lower limit ranges of K ₂ O are 0% or more and 0.1% or more. , 0.5% or more, 1% or more, 1.5% or more, especially 2% or more. Further, when it is desired to avoid the addition of K ₂ O as much as possible, the content of K ₂ O is preferably 0 to 1%, 0 to less than 1.0%, and particularly 0 to 0.05%. If the content of K ₂ O is too large, the coefficient of thermal expansion becomes unreasonably high, the thermal impact resistance is lowered, and it becomes difficult to match the coefficient of thermal expansion of the peripheral material. In addition, the strain point tends to decrease too much, or the component balance of the glass composition is disturbed, and the devitrification resistance tends to decrease.

In addition to the above components, for example, the following components may be added.

B ₂ O ₃ is a component that lowers the high temperature viscosity, density, slow cooling point, softening point, etc., stabilizes the glass, makes it difficult for crystals to precipitate, and lowers the liquidus temperature. It is also a component that reduces the crack generation rate and enhances scratch resistance. However, if the content of B ₂ O ₃ is too large, ion exchange tends to cause coloring of the glass surface, which is called discoloration, deterioration of water resistance, and reduction of stress depth. Therefore, the preferred range of B ₂ O ₃ is 0-10%, 0-9%, 0-8%, 0-7%, 0-6%, 0-5%, 0-4%, 0-3%. , 0.1-2%, especially 0.5-1%.

Li ₂ O is an ion exchange component, and is a component that lowers the high-temperature viscosity and enhances meltability, moldability, heat processability, and the like. Li ₂ O is a component that increases Young's modulus. The content of Li ₂ O is preferably 0 to 10%, 0 to 9%, 0 to 8%, 0 to 7%, 0 to 6%, 0 to 5%, 0 to 4%, 0 to 3%, 0 to 2%, 0 to 1.7%, 0 to 1.5%, 0 to 1%, 0 to less than 1.0%, 0 to 0.5%, 0 to 0.3%, 0 to 0. It is 1%, especially 0 to 0.05%. Li ₂ O has a large effect of increasing the compressive stress value among alkali metal oxides, but in a glass system containing 7% or more of Na ₂ O, when the Li ₂ O content becomes extremely large, the compressive stress value is rather high. Tends to decrease. Further, if the content of Li ₂ O is too large, the liquidus viscosity is lowered and the glass is easily devitrified. In addition, the coefficient of thermal expansion is unreasonably high and the thermal shock resistance is lowered. It becomes difficult to match with the coefficient of thermal expansion of peripheral materials. Further, the low-temperature viscosity is lowered too much, stress relaxation is likely to occur during the ion exchange treatment, and the compressive stress value may be lowered. Further, the eluted Li ions tend to deteriorate the ion exchange solution, and it becomes difficult to secure a desired compressive stress value by the ion exchange treatment.

MgO is a component that lowers the high-temperature viscosity and enhances meltability, formability, thermal processability, etc., and is a component that increases the strain point and Young's modulus. Further, among alkaline earth metal oxides, ions It is a component that has a great effect of enhancing exchange performance. Therefore, the suitable lower limit range of MgO is 0% or more, 0.1% or more, 0.5% or more, 1% or more, 1.5% or more, particularly 2% or more, and the preferable upper limit range of MgO is 10. % Or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, especially 3% or less. If the content of MgO is too small, it becomes difficult to enjoy the above effect. On the other hand, if the content of MgO is too large, the density and the coefficient of thermal expansion tend to be high, and the glass tends to be devitrified. In particular, when a glass plate is formed by an overflow downdraw method using an alumina molded body, devitrified crystals of spinel are likely to precipitate at the interface with the alumina molded body.

Compared with other components, CaO lowers the high-temperature viscosity without lowering the devitrification resistance, improves the meltability, moldability, heat workability, etc., and raises the strain point and Young's modulus. The effect is great. However, if the CaO content is too high, the density and the coefficient of thermal expansion tend to increase, the ion exchange performance tends to deteriorate, and the ion exchange solution tends to deteriorate. Therefore, the suitable content of CaO is 0-6%, 0-5%, 0-4%, 0-3.5%, 0-3%, 0-2%, 0-1%, especially 0-0. It is 5.5%.

SrO and BaO are components that lower the high-temperature viscosity to improve meltability, moldability, thermal processability, etc., and increase the strain point and Young's modulus, but if the content is too large, an ion exchange reaction will occur. In addition to being easily disturbed, the density and coefficient of thermal expansion are high, and the glass is easily devitrified. Therefore, the suitable contents of SrO and BaO are 0 to 2%, 0 to 1.5%, 0 to 1%, 0 to 0.5%, 0 to 0.1%, and particularly 0 to 0.1, respectively. Less than%.

TiO ₂ is a component that enhances ion exchange performance and a component that lowers high-temperature viscosity, but if the content is too large, the glass is easily colored or devitrified. Therefore, the suitable content of TiO ₂ is 0 to 4.5%, 0 to 0.5%, and particularly 0 to 0.3%.

ZrO ₂ is a component that enhances ion exchange performance and also a component that enhances viscosity and strain points near the liquid phase viscosity. However, if the content is too large, the devitrification resistance may be significantly reduced. There is also a risk that the density will be too high. Therefore, the suitable content of ZrO ₂ is 0 to 5%, 0 to 4%, 0 to 2%, 0-1%, and particularly less than 0 to 0.1%.

ZnO is a component that enhances the ion exchange performance, particularly a component that has a large effect of increasing the compressive stress value. It is also a component that lowers the high temperature viscosity without lowering the low temperature viscosity. However, if the ZnO content is too high, the glass tends to be phase-separated, the devitrification resistance is lowered, the density is high, and the stress depth is low. Therefore, the suitable content of ZnO is 0 to 6%, 0 to 5%, 0 to 3%, and particularly 0 to 1%.

P ₂ O ₅ is a component that enhances the ion exchange performance, and is a component that particularly increases the stress depth. However, if the content of P ₂ O ₅ is too large, the glass tends to be phase-separated and the water resistance tends to decrease. Therefore, the suitable content of P ₂ O ₅ is 0 to 10%, 0 to 3%, 0-1%, and particularly 0 to 0.5%.

SnO ₂ has the effect of enhancing the ion exchange performance. Therefore, the suitable content of SnO ₂ is 0 to 3%, 0.01 to 3%, 0.05 to 3%, 0.1 to 3%, and particularly 0.2 to 3%.

As the clarifying agent, one or more selected from the group of Cl, SO ₃ and CeO ₂ (preferably the group of Cl and SO ₃ ) may be added in an amount of 0 to 3%.

Suitable contents of Fe ₂ O ₃ are less than 1000 ppm (less than 0.1%), less than 800 ppm, less than 600 ppm, less than 400 ppm, especially less than 300 ppm. Furthermore, after limiting the content of Fe ₂ O ₃ to the above range, the molar ratio Fe ₂ O ₃ / (Fe ₂ O ₃ + SnO ₂ ) should be 0.8 or more, 0.9 or more, especially 0.95 or more. It is preferable to regulate. By doing so, the internal transmittance at a wavelength of 400 to 770 nm and a plate thickness of 1 mm can be easily improved (for example, 90% or more).

Rare earth oxides such as Nd ₂ O ₃ and La ₂ O ₃ are components that increase Young's modulus. However, the cost of the raw material itself is high, and if a large amount is added, the devitrification resistance tends to decrease. Therefore, the content of the rare earth oxide is preferably 3% or less, 2% or less, 1% or less, 0.5% or less, 0.2% or less, and particularly preferably less than 0.1%.

From the viewpoint of environmental consideration, it is preferable that the glass composition does not substantially contain As ₂ O ₃ , Sb ₂ O ₃ , PbO, Bi ₂ O ₃ , F and the like. "Substantially free of ..." means that although the specified component is not positively added as a glass component, it is allowed to be mixed as an impurity. Specifically, the content of the specified component is It means that it is less than 0.05%.

In the method for producing a tempering glass of the present invention, it is preferable to have a compounding step of blending a glass raw material so as to obtain a tempering glass having the following glass characteristics to obtain a glass batch.

The density is preferably 2.6 g / cm ³ or less, 2.55 g / cm ³ or less, 2.50 g / cm ³ or less, 2.48 g / cm ³ or less, 2.46 g / cm ³ or less, especially 2.45 g / It is cm ³ or less. The smaller the density, the lighter the reinforcing glass can be. It should be noted that the content of SiO ₂ , B ₂ O ₃ , and P ₂ O ₅ in the glass composition is increased, and the content of alkali metal oxide, alkaline earth metal oxide, ZnO, ZrO ₂ , and TiO ₂ is reduced. If this is done, the density tends to decrease.

The slow cooling point is preferably 700 ° C. or lower, 680 ° C. or lower, 660 ° C. or lower, 640 ° C. or lower, 620 ° C. or lower, 600 ° C. or lower, 580 ° C. or lower, 560 ° C. or lower, and particularly 540 ° C. or lower. If the cooling point is too high, the heat workability tends to decrease. If the content of B ₂ O ₃ and alkali metal oxide in the glass composition is increased, the slow cooling point tends to be lowered, and conversely, if the content of SiO ₂ and Al ₂ O ₃ is increased, the slow cooling point is likely to be lowered. The point is likely to rise.

The softening points are preferably 1000 ° C. or lower, 980 ° C. or lower, 960 ° C. or lower, 940 ° C. or lower, 920 ° C. or lower, 900 ° C. or lower, 880 ° C. or lower, 860 ° C. or lower, 840 ° C. or lower, 820 ° C. or lower, particularly 800 ° C. or lower. Is. If the softening point is too high, the heat workability tends to decrease. If the contents of B ₂ O ₃ and alkali metal oxide in the glass composition are increased, the softening point tends to be lowered, and conversely, if the contents of SiO ₂ and Al ₂ O ₃ are increased, the softening point is lowered. It becomes easy to rise.

The temperature at a high temperature viscosity of 10 ^4.0 dPa · s is preferably 1400 ° C. or lower. The lower the temperature at the high temperature viscosity of 10 ^4.0 dPa · s, the less the burden on the molding equipment, the longer the life of the molding equipment, and as a result, the easier it is to reduce the manufacturing cost of the reinforcing glass. Here, the "temperature at a high temperature viscosity of 10 ^4.0 dPa · s" can be measured by, for example, a platinum ball pulling method. If the contents of alkali metal oxides, alkaline earth metal oxides, ZnO, B ₂ O ₃ and TiO ₂ are increased, or the contents of SiO ₂ and Al ₂ O ₃ are reduced, ^104.0 The temperature at dPa · s tends to decrease.

The temperature at a high temperature viscosity of 10 ^2.5 dPa · s corresponds to the melting temperature, preferably 1700 ° C. or lower, 1680 ° C. or lower, 1650 ° C. or lower, 1600 ° C. or lower, 1580 ° C. or lower, 1550 ° C. or lower, especially 1500 ° C. or lower. be. The lower the temperature at the high temperature viscosity of 10 ^2.5 dPa · s, the lower the temperature melting becomes possible, the burden on the glass manufacturing equipment such as the glass melting kiln is reduced, and the foam quality is easily improved, resulting in strengthening. It becomes easy to reduce the manufacturing cost of glass for use. Here, the "temperature at a high temperature viscosity of 10 ^2.5 dPa · s" can be measured by, for example, a platinum ball pulling method. If the content of alkali metal oxide, alkaline earth metal oxide, ZnO, B2 O ₃ and TiO ₂ in the glass composition is increased or the content of SiO ₂ and Al ₂ O ₃ is decreased _, the content may be increased. The temperature at a high temperature viscosity of 10 ^2.5 dPa · s tends to decrease.

The liquid phase temperature is preferably 1300 ° C. or lower, 1280 ° C. or lower, 1250 ° C. or lower, 1230 ° C. or lower, 1200 ° C. or lower, 1170 ° C. or lower, 1150 ° C. or lower, 1100 ° C. or lower, 1070 ° C. or lower, 1050 ° C. or lower, 1020 ° C. or lower. , 1000 ° C or lower, especially 980 ° C or lower. The lower the liquidus temperature, the better the devitrification resistance and moldability. In addition, increase the content of Na ₂ O, K ₂ O, B ₂ O ₃ in the glass composition, or reduce the content of Al ₂ O ₃ , Li ₂ O, MgO, ZnO, TiO ₂ , and ZrO ₂ . If so, the liquidus temperature tends to decrease.

The liquidus viscosity is preferably 10 ^4.0 dPa · s or higher, 10 ^4.4 dPa · s or higher, 10 ^4.8 dPa · s or higher, 10 ^5.0 dPa · s or higher, and 10 ^5.3 dPa · s. ^105.5 dPa · s or more, 10 ^5.7 dPa · s or more, 10 ^5.8 dPa · s or more, especially 10 ^6.0 dPa · s or more. The higher the liquidus viscosity, the better the devitrification resistance and moldability. Further, if the content of Na ₂ O and K ₂ O in the glass composition is increased or the content of Al ₂ O ₃ , Li ₂ O, MgO, ZnO, TiO ₂ and ZrO ₂ is decreased, the liquid phase viscosity is increased. Tends to be high.

The Young's modulus is preferably 60 GPa or more, 62 GPa or more, 65 GPa or more, 67 GPa or more, 69 GPa or more, 70 GPa or more, 71 GPa or more, 75 GPa or more, and particularly 77 GPa or more. The higher the young rate, the more difficult it is for the tempered glass to bend. It becomes easy to prevent a situation where a display defect occurs due to contact with a positioned liquid crystal element. In addition, since the amount of deformation with respect to the stress generated during the ion exchange process is small, the dimensional change before and after the ion exchange process is reduced.

The β-OH value (β-OH value of the entire glass) of the strengthening glass before the contact step is preferably 1.0 / mm or less, 0.9 / mm or less, 0.8 / mm or less, 0.7 / It is mm or less, 0.6 / mm or less, 0.5 / mm or less, 0.4 / mm or less, and particularly 0.3 / mm or less. If the β-OH value is too large, it becomes difficult to enjoy the effect of increasing the crack resistance after the contact step, and the ion exchange performance tends to deteriorate. The β-OH value is an index of the amount of water in the glass and can be obtained by the following formula 1.

[Number 1]
β-OH value = (1 / X) log ₁₀ (T ₁ / T ₂ )
X: Glass wall thickness (mm)
T ₁ : Transmittance (%) at a reference wavelength of 3846 cm ^-1 (2600 nm)
T ₂ : Minimum transmittance (%) near hydroxyl group absorption wavelength 3600 cm ^-1 (2800 nm)

The method for producing reinforcing glass of the present invention includes a melting step of melting a glass batch to obtain molten glass. The charging of the glass batch into the glass melting kiln is usually performed continuously by a raw material feeder such as a screw charger, but may be performed intermittently.

The glass batch put into the glass melting kiln is heated by a combustion atmosphere such as a burner or an electrode installed inside the glass melting kiln to become molten glass. The melting temperature of the glass batch is, for example, about 1500 to 1650 ° C.

Subsequently, the obtained molten glass is supplied to the molding apparatus while being gradually cooled through a clarification step and a stirring step.

The method for producing a tempering glass of the present invention includes a molding step of molding molten glass into a predetermined shape to obtain a tempering glass, and the molding step is preferably a step of molding into a flat plate shape by an overflow downdraw method. If the glass ribbon is formed into a flat plate shape by the overflow down draw method, temperature differences and composition differences between the front and back surfaces of the glass ribbon are unlikely to occur during molding, and it becomes easy to form a reinforced glass plate that is unpolished and has good surface quality. The reason for this is that in the case of the overflow down draw method, the surface to be the surface does not come into contact with the gutter-shaped refractory and is formed in a free surface state.

In addition to the overflow down draw method, molding can also be performed by a slot down draw method, a float method, a rollout method, a redraw method, or the like. In the float method, the temperature difference and composition difference between the front and back surfaces of the glass ribbon are likely to occur during molding, but if the temperature control during molding is strictly performed, the temperature difference and composition difference can be reduced.

In the method for producing a tempering glass of the present invention, it is preferable to have a slow cooling step of slowly cooling the tempering glass after the molding step and before the contacting step, in which case the slow cooling temperature is (slow cooling point-50). The temperature range from (° C.) to (slow cooling point + 100 ° C.), particularly (slow cooling point -10 ° C) to (slow cooling point + 50 ° C.) is preferable, and the slow cooling time is preferably 10 to 120 minutes, particularly preferably 20 to 60 minutes. .. By doing so, it becomes easier to enjoy the effect of reducing the crack generation rate of the reinforcing glass by the contact process.

The method for producing a tempering glass of the present invention includes a contacting step of bringing the tempering glass into contact with a moist atmosphere having a humidity of 60 to 99%. The contact step is preferably performed in an airtight container in order to control the conditions of the moist atmosphere, but it is not necessary to use a completely airtight container as long as the moist atmosphere can be maintained.

Suitable lower limit range of humidity in a moist atmosphere is 65% or more, 70% or more, 75% or more, 80% or more, particularly 85% or more, and suitable upper limit range of humidity is 99% or less, 97% or less, Especially 95% or less. If the humidity is too low, it becomes difficult to reduce the crack occurrence rate of the reinforcing glass, and it becomes difficult to obtain the effect of reducing surface scratches. On the other hand, if the humidity is too high, the equipment cost for carrying out the contact process may increase.

The preferred lower limit of the temperature in the moist atmosphere is 27 ° C. or higher, 28 ° C. or higher, 29 ° C. or higher, 30 ° C. or higher, 35 ° C. or higher, 40 ° C. or higher, 45 ° C. or higher, particularly 50 ° C. or higher, and the temperature is suitable. The upper limit range is 1000 ° C. or lower, 900 ° C. or lower, 800 ° C. or lower, 700 ° C. or lower, 600 ° C. or lower, 500 ° C. or lower, 400 ° C. or lower, 300 ° C. or lower, 200 ° C. or lower, particularly 100 ° C. or lower. If the temperature is too low, it becomes difficult to reduce the crack occurrence rate of the reinforcing glass, and it becomes difficult to obtain the effect of reducing surface scratches. On the other hand, if the temperature is too high, the equipment cost for carrying out the contact process may increase.

The preferred lower limit of the process time of the contact step is 0.5 minutes or more, 1 minute or more, 2 minutes or more, 3 minutes or more, 4 minutes or more, 5 minutes or more, 7 minutes or more, 10 minutes or more, 12 minutes or more, 15 minutes. Minutes or more, 30 minutes or more, 1 hour or more, 2 hours or more, 6 hours or more, 12 hours or more, 24 hours or more, particularly 48 hours or more, and a suitable upper limit of the process time is 500 hours or less, 200 hours or less. , 150 hours or less, especially 100 hours or less. If the process time is too short, it becomes difficult to reduce the crack occurrence rate of the reinforcing glass, and it becomes difficult to obtain the effect of reducing surface scratches. On the other hand, if the process time is too long, the manufacturing efficiency of the tempering glass tends to decrease.

When the temperature in the moist atmosphere is T (° C.) and the contact time of the reinforcing glass is t (hours), the preferable lower limit range of 0.5 × ln (t) -5021 / (T + 273) is -14.0 or more. , -13.8 or higher, -13.6 or higher, -13.4 or higher, -13.2 or higher, especially -13.0 or higher, and suitable upper limit ranges are -7.5 or lower, -7.7 or lower. , -7.9 or less, -8.0 or less, -8.2 or less, -8.4 or less, -8.6 or less, -8.8 or less, -9.0 or less, -9.2 or less,- 9.4 or less, -9.6 or less, -9.8 or less, -10.0 or less, -10.2 or less, -10.4 or less, -10.6 or less, -10.8 or less, especially -11 It is less than or equal to 0.0. When 0.5 × ln (t) -5021 / (T + 273) is out of the above range, it becomes difficult to reduce the crack generation rate of the reinforcing glass, and it becomes difficult to obtain the effect of reducing surface scratches.

The β-OH value of the glass surface of the strengthening glass after the contact process is 3% or more, 5% or more, 7% or more, 10% or more, 15% or more, 20% or more, 30% compared to before the contact process. As mentioned above, it is preferable that the increase is 40% or more, particularly 50% or more, and the amount of increase is preferably 200% or less, 180% or less, 160% or less, and particularly preferably 150% or less. If the increase in the β-OH value on the glass surface is too small, it becomes difficult to reduce the crack generation rate of the reinforcing glass, and it becomes difficult to obtain the effect of reducing surface scratches. On the other hand, if the increase in the β-OH value on the glass surface is too large, the process time becomes long and the manufacturing efficiency of the reinforcing glass tends to decrease. Here, the β-OH value on the glass surface can be obtained by the following mathematical formula 2.

[Number 2]
Β-OH value on the glass surface = B + (BA) ÷ (50/1000)
A: β-OH value measured after polishing to a depth of 50 μm from the surface layer of glass B: β-OH value measured before polishing

The method for producing tempered glass of the present invention is characterized in that, in the method for producing tempered glass in which the tempered glass is ion-exchanged to obtain tempered glass, the tempered glass is produced by the above-mentioned method for producing tempered glass. do.

When the tempered glass is ion-exchanged, tempered glass having a compressive stress layer on the surface can be obtained. The compressive stress value of the compressive stress layer is preferably 300 MPa or more, 400 MPa or more, 500 MPa or more, 600 MPa or more, 700 MPa or more, 800 MPa or more, 900 MPa or more, 950 MPa or more, 1000 MPa or more, 1100 MPa or more, 1150 MPa or more, 1200 MPa or more, 1250 MPa or more, It is 1300 MPa or more, especially 1350 MPa or more. The stress depth is preferably 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, and particularly 45 μm or more.

The conditions for the ion exchange treatment are not particularly limited, and the optimum conditions may be selected in consideration of the viscosity characteristics of the glass, the application, the thickness, the internal tensile stress, the dimensional change, and the like. For example, the ion exchange treatment can be carried out by immersing in a KNO ₃ molten salt at 390 to 480 ° C. for 2 to 6 hours. In particular, when K ions in the KNO ₃ molten salt are ion-exchanged with the Na component in the glass, a compressive stress layer can be efficiently formed on the surface of the glass.

Hereinafter, the present invention will be described in detail based on examples. However, the following examples are merely examples. The present invention is not limited to the following examples.

Table 1 shows the sample No. It shows 1 to 16 glass compositions and glass properties.

Each sample was prepared as follows. First, glass raw materials were prepared so as to have the glass composition shown in the table, and after obtaining a glass batch, the glass batch was put into a platinum pot and melted at 1580 ° C. for 8 hours. The obtained molten glass was poured onto a carbon plate and molded into a flat plate shape. Various properties of the obtained glass were evaluated.

The density ρ is a value measured by the well-known Archimedes method.

The strain point Ps and the slow cooling point Ta are values measured based on the method of ASTM C336.

The softening point Ts is a value measured based on the method of ASTM C338.

The temperature at the high temperature viscosity of 10 ^4.0 dPa · s, 10 ^3.0 dPa · s, and 10 ^2.5 dPa · s is a value measured by the platinum ball pulling method.

The coefficient of thermal expansion α is a value obtained by measuring the average coefficient of thermal expansion in the temperature range of 25 to 380 ° C. using a dilatometer.

The liquidus temperature TL passes through a standard sieve of 30 mesh (seam opening 500 μm), and the glass powder remaining in 50 mesh (siege opening 300 μm) is placed in a platinum boat and then held in a temperature gradient furnace for 24 hours. , It is a value measured by the temperature at which crystals precipitate.

The liquid phase viscosity logηTL is a value obtained by measuring the viscosity of glass at the liquid phase temperature by the platinum ball pulling method.

Young's modulus E is a value measured by a well-known resonance method.

Next, both surfaces of each sample were optically polished and then immersed in a KNO ₃ molten salt at 430 ° C. for 4 hours to perform an ion exchange treatment. The surface of each sample was washed after the ion exchange treatment. Subsequently, the compressive stress value CS and the stress depth DOL of the compressive stress layer on the surface were calculated from the number of interference fringes observed using a surface stress meter (FSM-6000 manufactured by Toshiba Corporation) and their intervals. In the calculation, the refractive index of each sample was 1.50, and the optical elastic constant was 30 [(nm / cm) / MPa].

In addition, sample No. The materials of 2 and 16 were formed into a flat plate shape having a plate thickness of 0.55 mm by an overflow downdraw method, and then cut into a rough shape of 50 mm × 50 mm to obtain a plurality of glass plates. The average surface roughness Ra of the glass plate was 2 Å or less.

The crack occurrence rate was measured as follows. First, the Vickers indenter set to a load of 800 gf or 1600 gf is driven into the glass surface (optically polished surface) for 15 seconds after being kept in a constant temperature and humidity chamber maintained at a humidity of 30% and a temperature of 25 ° C., and 15 seconds later. The number of cracks generated from the four corners of the indentation is counted (maximum of 4 per indentation). In this way, the indenter was driven 50 to 100 times to obtain the total number of cracks generated, and then the total number of cracks generated / (number of times the indenter was driven × 4) × 100 was calculated.

Further, the glass plate was placed under the conditions of the moist atmosphere shown in Table 2, and after performing the contact step with the moist atmosphere, the crack generation rate was determined by the above method. The results are shown in Table 2. The sample F was subjected to a slow cooling treatment at a temperature of (slow cooling point Ta + 50 ° C.) for 30 minutes before the glass plate was put into the moist atmosphere.

As can be seen from Table 2, the sample A contained 14.5% by mass of Na _2O in the glass composition and the humidity in the moist atmosphere was 90%, so that the crack generation rate decreased by 17% after the contact step. The β-OH value on the glass surface of the sample A after the contact step was 7% higher than that before the contact step. Since the humidity of the sample B in the moist atmosphere was 50%, the crack generation rate did not decrease after the contact step. Since the sample C did not contain Na ₂ O in the glass composition and the humidity in the moist atmosphere was 50%, the crack generation rate did not decrease after the contact step. Since the sample D did not contain Na ₂ O in the glass composition, the crack generation rate decreased by only 9% after the contact step. The β-OH value on the glass surface of the sample D after the contact step was 3% higher than that before the contact step. Since the humidity of the sample E in the moist atmosphere was 20%, the crack generation rate did not decrease after the contact step. Sample F contained 14.5% by mass of Na _2O in the glass composition and was slowly cooled before the contact step with the moist atmosphere. Since the humidity in the moist atmosphere was 90%, cracks were generated after the contact step. The rate dropped by 37%.

In the above experiment, sample No. Although the glass of No. 2 was used, the sample No. It is considered that the same effect can be enjoyed with 1, 3 to 15 glasses.

The tempered glass produced by the present invention is suitable as a cover glass for mobile phones, digital cameras, PDAs, etc., or as a glass substrate for touch panel displays, etc. In addition to these applications, the tempered glass produced by the present invention is used for applications requiring high design, such as window glass, flat panel display substrate, solar cell cover glass, and solid image pickup element cover glass. , Application to tableware is desired.

Claims (7)

As a glass composition, a strengthening glass containing SiO ₂ 40 to 75%, Al ₂ O ₃₀ to 30%, Na ₂ O 5 to 25%, and K ₂ O 0 to 10% in mass% can be obtained. , The compounding process of compounding glass raw materials to obtain a glass batch,
The melting process of melting a glass batch to obtain molten glass,
A molding process in which molten glass is formed into a predetermined shape and cut to obtain glass for strengthening.
A slow cooling process that slowly cools the strengthening glass after the molding process,
A method for producing a reinforcing glass, which comprises a contacting step of bringing the strengthening glass after a slow cooling step into contact with a moist atmosphere having a humidity of 60 to 99% and a temperature of 65 ° C. or lower. When the temperature in the moist atmosphere is T (° C.) and the contact time of the strengthening glass is t (hours), -14.0 ≦ 0.5 × ln (t) -5021 / (T + 273) ≦ -7.5. The method for manufacturing a reinforcing glass according to claim 1, wherein the relationship is satisfied. The method for producing a reinforcing glass according to claim 1 or 2, wherein the molten glass is formed into a flat plate shape. In a method for manufacturing tempered glass, which obtains tempered glass by ion-exchange treatment of tempered glass.
A method for producing tempered glass, which comprises producing the tempered glass by the method for producing tempered glass according to any one of claims 1 to 3. The method for manufacturing tempered glass according to claim 4, wherein the tempered glass is used as a cover glass of a touch panel display. The method for producing tempered glass according to claim 4, wherein the tempered glass is used for a substrate or a cover glass of a solar cell. The method for producing tempered glass according to claim 4, wherein the tempered glass is used as an exterior member.