JP6769441B2 - Wind-cooled tempered glass and wind-cooled tempered glass - Google Patents

Description

The present invention relates to a wind-cooled strengthening glass capable of applying sufficient residual stress by wind-cooling strengthening even when a thin glass having a thickness of 2.5 mm or less is used.
The present invention also relates to an air-cooled tempered glass obtained by air-cooling the tempered glass of the present invention.

Tempered glass has improved the drawback of being easily broken, which is a problem of general glass, and is used for transportation equipment, construction, and the like. Examples of transportation equipment include passenger cars, trucks, buses, railways, ships, aircraft, etc., and are used for windows, headlights, taillights, and the like. In addition, examples of architecture include buildings, houses, etc., which are used for doors, partitions, etc. In addition, it is widely used for furniture such as bookshelves and showcases, electrical appliances such as cooking utensils, and office supplies.

Tempered glass is produced, for example, by a method called heat strengthening. The heat strengthening utilizes the heat shrinkage of the glass during cooling, and cools the glass after heating it to a temperature near the softening point or the yield point. At this time, since the surface temperature drops faster than the internal temperature drop, a temperature difference occurs in the thickness direction, tensile stress and internal compressive stress are generated on the surface, and then reversal based on the stress relaxation phenomenon. As a result, compressive stress and tensile stress are generated on the surface and remain inside. Since the compressive stress remains on the surface, the strength is improved, the growth of scratches is suppressed, and the scratch resistance is improved. Typical examples of heat strengthening include wind cooling strengthening in which plate-shaped glass is manufactured by a float method or the like, the cut glass plate is heated to a temperature near the softening point or yield point, and then a cooling medium is sprayed on the surface to quench the glass. It is a typical one.

In recent years, there has been a demand for weight reduction of tempered glass in transportation equipment, construction and the like. The weight reduction of tempered glass can be achieved by reducing the thickness thereof, and for example, the thickness is required to be 2.5 mm or less. However, since heat strengthening utilizes the temperature difference between the surface and the inside during cooling, if the thickness is reduced, the temperature difference between the surface and the inside cannot be increased, and full-scale strengthening is difficult.

As a method for producing a thin tempered glass, for example, it is known to use a glass composition having a predetermined glass composition and having an average linear expansion coefficient of 80 to 110 × 10 ^-7 / ° C at 50 to 350 ° C. (See, for example, Patent Document 1).
However, in such a manufacturing method, since only the average coefficient of linear expansion on the low temperature side is controlled, it is not always possible to effectively apply residual stress to thin glass having a thickness of 2.5 mm or less.

Further, in a solar cell module having a structure in which both sides are sandwiched by glass, such as the solar cell module described in Patent Document 2, since the weight of the glass substrate occupies most of the module weight, the glass substrate is thinned and lightweight. The merit of making it is very big. Therefore, a glass substrate made of chemically strengthened glass is used as the light receiving face plate and the back plate. This is because chemically strengthened glass can apply sufficient residual stress even if the thickness is 2.5 mm or less.
However, since the chemically strengthened glass is more expensive than the air-cooled tempered glass, the solar cell module described in Patent Document 2 using the chemically strengthened glass as the light receiving face plate and the back plate is expensive.

Japanese Unexamined Patent Publication No. 2003-119048 Japanese Unexamined Patent Publication No. 2013-247238

The present invention has been made in view of the above problems, and is for air cooling strengthening, in which sufficient residual stress can be applied by air cooling strengthening even when a thin glass having a thickness of 2.5 mm or less is used. An object of the present invention is to provide a glass and an air-cooled tempered glass obtained by air-cooling tempered glass.

In order to achieve the above object, the present invention has a Fe ³⁺ content of 2.2% by mass or more in terms of Fe ₂ O ₃ and a Fe ²⁺ content of 0.8% by mass in terms of Fe ₂ O _3. The average coefficient of thermal expansion α ₅₀ to 350 at 50 to 350 ° C is 75 × 10 ^-7 / ° C or higher and 90 × 10 ^-7 / ° C or lower, and the glass transition point is 500 ° C or higher and 600 ° C or lower. Provided is a wind-cooled strengthening glass characterized in that the maximum value α _{max of the} coefficient of thermal expansion between the glass transition point and the yield point is 410 × 10 ^-7 / ° C. or higher.

The present invention also provides an air-cooled tempered glass obtained by air-cooling the tempered glass of the present invention.

Even when the wind-cooled strengthening glass of the present invention is a thin glass having a thickness of 2.5 mm or less, sufficient residual stress can be applied by the wind-cooling strengthening.

FIG. 1 is a schematic plan view of a portion where a cooling nozzle of the air cooling strengthening equipment used in the embodiment is provided.

The wind-cooled strengthening glass of the present invention has a glass transition point of 500 ° C. or higher. As described above, in the wind-cooling strengthening treatment, plate-shaped glass is produced by a float method or the like, the cut glass plate is heated to a temperature near the softening point or the yield point, and then a cooling medium is sprayed on the surface to quench the glass. By doing so, residual stress is applied to the glass. However, when the glass transition point is less than 500 ° C., it is difficult to create a temperature difference between the surface and the inside by the heating step and the cooling step described above, and residual stress cannot be effectively applied. The glass transition point is preferably 530 ° C. or higher, more preferably 540 ° C. or higher. The upper limit of the temperature during the heating step is preferably the glass transition point + 200 ° C. If the upper limit of the temperature in the heating step is higher than the glass transition point + 200 ° C., the glass tends to be viscous flow deformed at a high temperature, and the optical quality of the final tempered glass may deteriorate.
On the other hand, if the glass transition point is too high, it is necessary to heat the glass to a high temperature in the heating step, and the peripheral members for holding the glass are exposed to the high temperature, so that the life of these may be significantly shortened. It is necessary to use an expensive member having excellent heat resistance in order to extend the temperature. Therefore, the glass transition point is 600 ° C. or lower, preferably 590 ° C. or lower, and more preferably 580 ° C. or lower.

The wind-cooled strengthening glass of the present invention has a maximum value α _{max of the} coefficient of thermal expansion between the glass transition point and the yield point (hereinafter, referred to as “high temperature thermal expansion coefficient α _max ” in the present specification) of 410. × 10 ^-7 / ° C or higher. When the high-temperature coefficient of thermal expansion α _max is less than 410 × 10 ^-7 / ° C, when thin glass with a thickness of 2.5 mm or less is used, residual stress is effectively applied using a general air cooling strengthening device. It may not be possible. Generally, the wind cooling strengthening is performed by quenching from a temperature about 100 ° C. higher than the glass transition point. By setting the high-temperature coefficient of thermal expansion α _max to 410 × 10 ^-7 / ° C or higher, even if a thin glass with a thickness of 2.5 mm or less is used, a general air cooling strengthening device can be used from such a temperature. It can be used to effectively apply residual stress.

Here, the coefficient of thermal expansion α _max means the maximum value of the coefficient of thermal expansion between the glass transition point and the yield point in the expansion coefficient curve of the glass to be treated measured by the thermal expansion meter as described later. The higher the coefficient of thermal expansion α _max is, the more preferable it is from the viewpoint of imparting residual stress, but usually 600 × 10 ^-7 / ° C. is sufficient. In addition, when the high-temperature thermal expansion coefficient α _max becomes large, the glass may break due to the temporary strain generated at the initial stage of cooling and the yield may deteriorate. Therefore, the high-temperature thermal expansion coefficient α _max is 410 × 10 ^-7 /. ℃ or more and preferably 600 × 10 ^-7 / ℃ or less, preferably 420 × 10 ^-7 / ℃ or more and 520 × 10 ^-7 / ℃ or less, 430 × 10 ^-7 / ℃ or more and 500 × 10 ^-7 / ℃ or less. More preferred.

The yield point of the wind-cooled strengthening glass of the present invention is not necessarily limited, but preferably exceeds 600 ° C. When the yield point is 600 ° C. or less, when the cut glass plate is heated to a temperature near the softening point or the yield point, the heating temperature, that is, the strengthening start temperature becomes low, and residual stress may not be effectively applied. .. The yield point is preferably 750 ° C. or lower. If the yield point exceeds 750 ° C, it is necessary to heat to a high temperature, and the peripheral members for holding the glass are exposed to a high temperature, so that the life of these may be significantly shortened and the life is extended. It is necessary to use an expensive member having excellent heat resistance. The yield point of the air-cooled strengthening glass of the present invention is more preferably 700 ° C. or lower.

The wind-cooled strengthening glass of the present invention _preferably has a large average coefficient of thermal expansion α ₅₀ to 350 at 50 to 350 ° C. from the viewpoint of imparting residual stress. If it is too large, expansion inconsistency with other current members may become a problem, or it may become vulnerable to thermal shock. Therefore, the average coefficient of thermal expansion α ₅₀ to ₃₅₀ is 75 × 10 ^-7 / ° C. or higher, more preferably 77 × 10 ^-7 / ° C. or higher, and even more preferably 79 × 10 ^-7 / ° C. or higher. On the other hand, the average coefficient of thermal expansion α ₅₀ to ₃₅₀ is 110 × 10 ^-7 / ° C or less, more preferably 100 × 10 ^-7 / ° C or less, and further preferably 95 × 10 ^-7 / ° C or less.

The wind-cooled reinforcing glass of the present invention has a difference in thermal expansion coefficient (Δα (= α _max −α _{50 to 350)} ) between a high-temperature thermal expansion coefficient α _max and an average thermal expansion coefficient α ₅₀ to _{350 at 50} to 350 ° C. )) Is preferably 345 × 10 ^-7 / ° C. or higher. When the coefficient of thermal expansion from low temperature to high temperature, that is, the coefficient of thermal expansion α _max and the average coefficient of thermal expansion α ₅₀ to ₃₅₀ at ₅₀ to 350 ° C. are simply increased, thermal shock occurs during the heating and cooling steps. Cracks due to, inconsistency of thermal expansion with other members, incompatibility with the current process, etc. are likely to occur.

By setting the coefficient of thermal expansion difference (Δα) to 345 × 10 ^-7 / ° C or higher, that is, while keeping the average coefficient of thermal expansion α ₅₀ to ₃₅₀ at ₅₀ to 350 ° C constant, the coefficient of thermal expansion α _max can be increased. By making it relatively large, even if it is a thin glass with a thickness of 2.5 mm or less, residual stress can be effectively applied using a general air cooling strengthening device, and cracks due to thermal shock occur. Can also be suppressed. The coefficient of thermal expansion difference (Δα) is more preferably 360 × 10 ^-7 / ° C. or higher, and further preferably 370 × 10 ^-7 / ° C. or higher. The larger the coefficient of thermal expansion difference (Δα) is, the more preferable it is. Normally, 500 × 10 ^-7 / ° C is sufficient, but the difference in coefficient of thermal expansion (Δα) is 420 × 10 ^-7 / ° C. The following is preferable, and 400 × 10 ^-7 / ° C. or less is more preferable.

Here, the glass transition point, the yield point, and the coefficient of thermal expansion (α _max , α _{50 to 350} ) are measured by the following methods. That is, a columnar sample having a diameter of 5 mm and a length of 20 mm was prepared, and the thermal expansion was measured using a thermal expansion meter at a heating rate of 5 ° C./min and under a load condition of 10 g. Obtain the coefficient of thermal expansion (α _max , α ₅₀ to ₃₅₀ ).

Since the air-cooled tempered glass utilizes the temperature difference between the surface and the inside caused by carrying out the heating step and the cooling step described above, if the thickness is reduced, the temperature difference between the surface and the inside cannot be increased. It was difficult to apply sufficient residual stress. As a result of diligent studies on this point, the inventor of the present application can increase α _max when the content of trivalent iron (Fe ³⁺ ) in the wind-cooling strengthening glass is increased, and as a result, wind-cooling can be performed. We have found that the residual stress of the reinforced glass is improved.
Since the air-cooled strengthening glass of the present invention has a Fe ³⁺ content of 2.2% by mass or more in terms of Fe ₂ O ₃ , it is generally used even when it is a thin glass having a thickness of 2.5 mm or less. Residual stress can be effectively applied by using a conventional air cooling strengthening device. Among them, the Fe ³⁺ content is preferably 2.5% by mass or more, more preferably 2.7% by mass or more in terms of Fe ₂ O ₃ .
The air-cooled strengthening glass of the present invention preferably has a Fe ³⁺ content of 6.0% by mass or less in terms of Fe ₂ O ₃ . When the Fe ³⁺ content is 6.0% by mass or less in terms of Fe ₂ O ₃ , the yellowness does not become too strong and the appearance is unlikely to deteriorate. Among them, the Fe ³⁺ content is more preferably 5.0% by mass or less in terms of Fe ₂ O ₃ , and further preferably 4.5% by mass or less.

The air-cooled strengthening glass of the present invention has a Fe ²⁺ content of 0.8% by mass or less in terms of Fe ₂ O ₃ . If the Fe ²⁺ content is higher than 0.8% by mass in terms of Fe ₂ O ₃ , it becomes difficult to raise the temperature of the melting kiln and the solubility of the glass decreases. Among them, the Fe ²⁺ content is preferably 0.7% by mass or less in terms of Fe ₂ O ₃ , and more preferably 0.6% by mass or less.
The air-cooled strengthening glass of the present invention preferably has a Fe ²⁺ content of 0.05% by mass or more in terms of Fe ₂ O ₃ . When the Fe ²⁺ content is 0.05% by mass or more in terms of Fe ₂ O ₃ , the temperature of the melting kiln does not rise too much and the solubility can be maintained. Among them, the Fe ²⁺ content is preferably 0.1% by mass or more in terms of Fe ₂ O ₃ , and more preferably 0.2% by mass or more.

The air-cooled strengthening glass of the present invention preferably has a Fe-Redox value of 5% or more and 60% or less. Here, the Fe-Redox, a ratio of Fe ²⁺ content in terms of Fe ₂ O ₃ to the total iron content in terms of Fe ₂ O _3. When the value of Fe-Redox is 60% or less, solarization is unlikely to occur and the color is unlikely to change, so that the color is unlikely to change during long-term use. The value of Fe-Redox is more preferably 55% or less, still more preferably 50% or less, and particularly preferably 45% or less. Further, when the value of Fe-redox is 5% or more, defoaming becomes easy and high-quality glass without bubbles can be produced. Among them, the value of Fe-Redox is more preferably 10% or more, further preferably 15% or more, and particularly preferably 20% or more.

The air-cooled strengthening glass of the present invention preferably contains the following components in terms of mass% based on oxides. In the present invention, the mass% based on the oxide is simply expressed as%.
SiO ₂ 66-75%,
Al ₂ O _{30 to} 15%,
B ₂ O ₃ 0~20%,
MgO + CaO + SrO + BaO 1-30%,
Li ₂ O + Na ₂ O + K ₂ O 1-25%

According to such a composition, the constituent components of soda lime glass generally used for producing tempered glass and the basic constituent components are the same, so that the productivity is improved. Further, according to such a composition, a glass transition point of 500 to 600 ° C. and a high temperature coefficient of thermal expansion α _max of 410 × 10 ^-7 / ° C. or higher can be obtained. Hereinafter, the range of composition of each component will be described.

The content of SiO ₂ is preferably 66 to 75%. If it is less than 66%, problems such as an increase in glass density, an increase in thermal expansion coefficient, and deterioration of scratch resistance occur. The content of SiO ₂ is preferably 67% or more, more preferably 68% or more. Further, when the content of SiO ₂ exceeds 75%, the viscosity becomes high and the glass becomes difficult to melt. The content of SiO ₂ is preferably 73% or less.

Al ₂ O ₃ can be contained as needed, and the content thereof is preferably 15% or less. If the content of Al ₂ O ₃ exceeds 15%, the coefficient of thermal expansion above the glass transition point is unlikely to increase, and it may be difficult to increase the residual stress. The content of Al ₂ O ₃ is preferably 10% or less, more preferably 5% or less.

B ₂ O ₃ can be contained as needed, and the content thereof is preferably 20% or less. If the content of B ₂ O ₃ exceeds 20%, the coefficient of thermal expansion above the glass transition point is unlikely to increase, and it may be difficult to increase the residual stress. The content of B ₂ O ₃ is preferably 15% or less, more preferably 10% or less.

The total content of the alkaline earth metal oxides, that is, MgO, CaO, SrO, and BaO (MgO + CaO + SrO + BaO) is preferably 1% or more. When MgO + CaO + SrO + BaO is less than 1%, a large amount of alkali metal oxides, that is, Li ₂ O, Na ₂ O, and K ₂ O, are added in order to maintain the solubility of the glass at high temperature and an appropriate coefficient of thermal expansion. As a result, the temperature difference between the strain point and the yield point may be small, and the residual stress may be small. MgO + CaO + SrO + BaO is preferably 3% or more, more preferably 5% or more, still more preferably 10% or more. MgO + CaO + SrO + BaO is preferably 30% or less. If it exceeds 30%, the devitrification tendency of the glass becomes stronger and the productivity deteriorates. The amount of MgO + CaO + SrO + BaO is preferably 25% or less.

The content of MgO is preferably 0.1% or more. MgO is necessary to maintain the coefficient of thermal expansion of the glass appropriately, and can improve the scratch resistance. The content of MgO is preferably 2% or more, more preferably 3% or more. The MgO content is preferably 25% or less. If the MgO content exceeds 25%, the devitrification tendency of the glass becomes stronger and the productivity deteriorates. The content of MgO is preferably 23% or less, more preferably 21% or less, still more preferably 20% or less.

The CaO content is preferably 0.1% or more. CaO is required to moderately maintain the coefficient of thermal expansion of the glass. The CaO content is preferably 2% or more, more preferably 3% or more. The CaO content is preferably 15% or less. When the CaO content exceeds 15%, the devitrification tendency of the glass becomes stronger and the productivity deteriorates. The CaO content is preferably 14% or less, more preferably 13% or less.

SrO can be contained as needed, and the content thereof is preferably 10% or less. By containing SrO, the solubility of glass at high temperature and the coefficient of thermal expansion can be adjusted. When the SrO content exceeds 10%, the density of the glass increases and the weight of the glass increases. When SrO is contained, it is preferably 1% or more, more preferably 1.5% or more. The content of SrO is more preferably 7% or less, still more preferably 5% or less.

BaO can be contained as needed, and the content thereof is preferably 10% or less. By containing BaO, the solubility of glass at high temperature and the coefficient of thermal expansion can be adjusted. On the other hand, when BaO is contained, the density of the glass increases, so that the weight of the glass tends to increase. In addition, when BaO is contained, the glass becomes brittle, so that the crack initiation load becomes low and the glass becomes easily damaged. Therefore, the content of BaO is preferably 7% or less, more preferably 5% or less, still more preferably 3% or less.

The total content of the alkali metal oxides, that is, Li ₂ O, Na ₂ O, and K ₂ O (Li ₂ O + Na ₂ O + K ₂ O) is preferably 1% or more. When Li ₂ O + Na ₂ O + K ₂ O is less than 1%, the alkaline earth metal oxides, ie, MgO, CaO, SrO, and It is necessary to add a large amount of BaO, and as a result, the devitrification tendency of the glass is increased and the productivity is deteriorated. Li ₂ O + Na ₂ O + K ₂ O is preferably 3% or more, more preferably 5% or more, further preferably 8% or more, and particularly preferably 10% or more. Li ₂ O + Na ₂ O + K ₂ O is preferably 25% or less. If it exceeds 25%, the temperature difference between the strain point and the yield point becomes small, and the residual stress may become small. Li ₂ O + Na ₂ O + K ₂ O is preferably 25% or less, more preferably 20% or less.

The Na ₂ O content is preferably 8% or more. Since Na ₂ O is a component in which the coefficient of thermal expansion increases even if the density of the glass is low, it is contained in the glass composition for the purpose of adjusting the coefficient of thermal expansion. The Na ₂ O content is preferably 9% or more, more preferably 10% or more. The Na ₂ O content is preferably 20% or less. When the Na ₂ O content exceeds 20%, the temperature difference between the strain point and the yield point becomes small, so that the strengthening stress becomes small and the coefficient of thermal expansion becomes too large. The Na ₂ O content is preferably 17% or less, more preferably 15% or less.

K ₂ O can be contained if necessary, but the content thereof is preferably 0.1% or more. When the K ₂ O content is 0.1% or more, the solubility of the glass at high temperature and an appropriate coefficient of thermal expansion can be maintained. The content of K ₂ O is more preferably 0.5% or more, and particularly preferably 1% or more. The content of K ₂ O is preferably 4% or less. When the K ₂ O content exceeds 4%, the density of the glass increases and the weight of the glass increases. The content of K ₂ O is preferably 3.5% or less, more preferably 3% or less.

The air-cooled strengthening glass of the present invention preferably comprises substantially the above-mentioned components, but contains up to 10% in total of other components as necessary and to the extent not contrary to the gist of the present invention. May be good. Examples of other components include ZrO ₂ , Y ₂ O ₃ , CeO ₂ , MnO, CoO and the like. Further, PbO and the like can be contained, but it is preferable that these are not substantially contained. In addition, "substantially not contained" means less than 0.01%.

Further, SO ₃ , chloride, fluoride, halogen, SnO ₂ , Sb ₂ O ₃ , As ₂ O _{3 and the} like may be appropriately contained as a fining agent when the glass is melted. Further, Ni, Cr, V, Se, Au, Ag, Cd and the like may be contained for adjusting the color. It is preferable that the glass to be treated is substantially free of As, Sb and Pb. Since these are toxic, they are preferably not contained in the glass to prevent environmental impact. In addition, "substantially not contained" means less than 0.01%.

Even when the glass for air cooling strengthening of the present invention is a thin glass having a thickness of 2.5 mm or less, residual stress can be effectively applied by using a general known wind cooling strengthening device or method. Can be made lighter. As a known air-cooling strengthening device or method used in the present invention, for example, a glass plate is arranged so as to be sandwiched between upper and lower air-cooling strengthening outlet members at a predetermined interval, and is rapidly cooled by cooling air. An example is an air cooling strengthening device.
From the viewpoint of weight reduction, the air-cooled strengthening glass of the present invention preferably has a thickness of 2.4 mm or less, more preferably 2.3 mm or less, 2.0 mm or less, 1.5 mm or less, and 1. 3 mm or less is more preferable. However, from the viewpoint of effectively applying residual stress, the plate thickness is preferably 0.5 mm or more, and more preferably 0.7 mm or more.

The air-cooled strengthening glass of the present invention is produced by any one of glass plate forming methods such as a float method, a fusion method, a download method, and a rollout method. According to the float method, it is easy to produce a glass plate having a large area, and it is easy to reduce the thickness deviation, which is preferable.

The air-cooled strengthening glass of the present invention is a thin glass having a thickness of 2.5 mm or less, and a thin glass having a thickness of 2.5 mm or less. The compressive stress value is preferably 110 MPa or more, more preferably 122 MPa or more, still more preferably 130 MPa or more.
When a thin glass having a thickness of 2.0 mm or less is used, the surface compressive stress value of the glass after air cooling strengthening is preferably 70 MPa or more, more preferably 78 MPa or more, still more preferably 85 MPa or more. ..
When a thin glass having a thickness of 1.5 mm or less is used, the surface compressive stress value of the glass after air-cooling strengthening is preferably 60 MPa or more, more preferably 65 MPa or more, still more preferably 70 MPa or more. ..

The air-cooled tempered glass of the present invention is a wind-cooled tempered glass of the present invention.
The thickness of the air-cooled tempered glass of the present invention varies depending on the application, but it is preferable to have a thickness of 2.5 mm or less due to the above-mentioned characteristics of the air-cooled tempered glass of the present invention.
The surface compressive stress value of the air-cooled tempered glass of the present invention varies depending on the thickness of the air-cooled tempered glass, but when the thickness is 2.5 mm or less, the surface compressive stress value is preferably 110 MPa or more, more preferably 110 MPa or more. Is 122 MPa or more, more preferably 130 MPa or more. When the thickness is 2.0 mm or less, the surface compressive stress value is preferably 70 MPa or more, more preferably 78 MPa or more, and further preferably 85 MPa or more. When the thickness is 1.5 mm or less, the surface compressive stress value is preferably 60 MPa or more, more preferably 65 MPa or more, still more preferably 70 MPa or more.

When used as the back plate of a solar cell module, if the air-cooled tempered glass is highly transparent, wiring and the like will be visually observed and the design will deteriorate. In order to improve the design, the air-cooled tempered glass preferably has a visible light transmittance (D65 light source) Tv_D65 specified in ISO-9050 (2003) of 82% or less, and more preferably 80% or less. It is preferably 77% or less, and more preferably 77% or less.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention should not be construed as being limited to these Examples.

Generally used glass raw materials such as various oxides were appropriately selected so as to have the glass composition shown in Table 1, and the mixture was placed in a platinum crucible. This crucible was put into a resistance heating type electric furnace at 1600 ° C., melted for 3 hours, defoamed and homogenized, then poured into a mold material and held at a temperature about 30 ° C. higher than the glass transition point for 1 hour or more. Then, the mixture was slowly cooled to room temperature at a cooling rate of 0.3 to 1 ° C. per minute. As a result, the plate-shaped glass samples of Examples 1 to 3 and Comparative Examples 1 to 9 shown in Table 1 were prepared.

The surface of the obtained glass sample was mirror-polished, and Fe-Redox was calculated from the spectral curve measured by a spectrophotometer using the following equation (1).

Fe-Redox (%) = (-log _e (T _{1000 nm /} 91.4) / (Fe ₂ O ₃ amount x t x 20.79)) x 100 ... (1).
However, in the formula (1), T _{1000 nm} is the transmittance (%) at a wavelength of 1000 nm measured by a spectrophotometer (Lambda950, manufactured by Perkin Elmer), and t is the thickness (cm) of the glass sample. , Fe ₂ O ₃ amount is the total iron content (% = mass percentage) in terms of Fe ₂ O ₃ determined by fluorescent X-ray measurement.
The Fe-Redox is a method of finding the spectral curve of the glass sample was measured by spectrophotometer, the value, Fe of terms of Fe ₂ O ₃ to the total iron content calculated as Fe ₂ O ₃ in the same glass It may be considered equal to the ratio of ²⁺ content.

Next, based on the JIS R 3103-3: 2001 standard, a columnar sample having a diameter of 5 mm and a length of 20 mm was prepared from the glass sample, and 5 using a thermal expansion meter (TMA4000SA, manufactured by Bruker AXS). The thermal expansion was measured at a heating rate of ° C./min and a load of 10 g, and the glass transition point (Tg) was determined.

Further, based on the JIS R 1618: 2002 standard, for the glass sample, the temperature rise rate of 5 ° C./min using a thermal expansion meter (TMA4000SA, manufactured by Bruker AXS Co., Ltd.) is the same as the measurement of the glass transition point. The coefficient of thermal expansion was measured, and the average coefficient of thermal expansion α ₅₀ to 350 at 50 to 350 ° C. and the high temperature coefficient of thermal expansion α _max were determined.
The visible light transmittance (Tv_D65) was measured using a spectrophotometer (Lambda950, manufactured by PerkinElmer).

Further, in order to evaluate the characteristics of the glass samples of Examples 1 to 3 and Comparative Examples 1 to 9 in the air cooling strengthening, the surface residual stress after the wind cooling strengthening was measured by the method shown below.
The glass sample was cut into a plate having a length of 550 mm and a width of 550 mm, and chamfered. A general roller transport type air cooling strengthening facility was used for the wind cooling strengthening treatment. FIG. 1 is a schematic plan view of a portion where a cooling nozzle of this air cooling enhancement facility is provided. In FIG. 1, the figure on the left side shows the shape of the end face of the portion where the cooling nozzle is provided.
As shown in FIG. 1, the plurality of cooling nozzles 20, 30, and 40 are arranged in a staggered manner. The nozzle 20 is provided in a direction perpendicular to the surface to be treated of the glass plate to be treated to be air-cooled. The nozzle 20 has a diameter of 3.1 mm, and the pitch between the nozzles 20 is 24 mm. The nozzles 30 and 40 are provided in an oblique direction with respect to the surface to be treated of the glass plate to be treated. The nozzles 30 and 40 each have a diameter of 3.9 mm, and the pitch between the nozzles 30 and the pitch between the nozzles 40 are both 24 mm. With respect to the nozzle 30, the pitch of the nearest nozzle 20 and the pitch of the nearest nozzle 40 are both 8 mm.

The distance between the nozzle 20 and the surface to be treated of the glass plate to be treated is 10 mm. The temperature of the air supplied from the nozzles 20, 30 and 40 as a cooling medium is 60 ° C., the wind pressure (outlet wind pressure) is 18 to 19 kPa, and the glass plate to be treated is heated to 630 to 635 ° C. Air was blown onto the treated surface as a cooling medium to cool it. The surface compressive stress value of the air-cooled tempered glass produced in this manner was measured with a glass surface stress meter (FSM-7000H manufactured by Orihara Seisakusho Co., Ltd.). The value obtained by dividing the surface compressive stress value of each sample by the surface compressive stress value of Comparative Example 5 was defined as the relative surface compressive stress value.

The glasses of Examples 1 to 3 having a high-temperature coefficient of thermal expansion α _max of 410 × 10 ^-7 / ° C. or higher had a relative surface compressive stress value of 1.1 or more after being air-cooled. The glasses of Comparative Examples 1 to 6 having a high-temperature coefficient of thermal expansion α _max of less than 410 × 10 ^-7 / ° C. had a relative surface compressive stress value of less than 1.1 after being air-cooled. The glasses of Comparative Examples 7 to 9 had a high temperature coefficient of thermal expansion α _max of 410 × 10 ^-7 / ° C or higher, but the Fe ²⁺ content was more than 0.8% by mass in terms of Fe ₂ O _3. , It becomes difficult to raise the temperature of the melting kiln, and the solubility of glass is low.

The air-cooled tempered glass of the present invention can be preferably used in various applications in which tempered glass is used. Specifically, it can be preferably used for automobile applications and building applications. Further, it can be preferably used as a light receiving face plate or a back plate of a solar cell module.

The specification, claims, drawings, and abstracts of Japanese Patent Application No. 2015-220596 filed on November 10, 2015 and Japanese Patent Application No. 2016-050851 filed on March 15, 2016. The entire contents of the document are cited herein and incorporated as disclosure of the specification of the present invention.

20, 30, 40: Nozzle

Claims (15)

The Fe ³⁺ content is 2.2% by mass or more in terms of Fe ₂ O ₃ , the Fe ²⁺ content is 0.6 % by mass or less in terms of Fe ₂ O ₃ , and the average heat at 50 to 350 ° C. The coefficient of expansion α ₅₀ to ₃₅₀ is 75 × 10 ^-7 / ° C or higher and 110 × 10 ^-7 / ° C or lower, the glass transition point is 500 ° C or higher and 600 ° C or lower, and thermal expansion between the glass transition point and the yield point. A wind-cooled strengthening glass characterized in that the maximum value α _{max of the} coefficient is 410 × 10 ^-7 / ° C or higher. Fe ³⁺ The content is Fe ₂ O ₃ The air-cooled strengthening glass according to claim 1, which is 2.5% by mass or more in terms of conversion. The air-cooled strengthening glass according to claim 1 or 2, wherein the value of Fe-Redox is 5% or more and 60% or less. A maximum value alpha _max of the thermal expansion coefficient between the glass transition point and deformation _point, thermal expansion coefficient difference between the average thermal expansion coefficient alpha _{50 to 350} at _{50~350 ℃ (Δα (= α max} -α 50~350 )) Is 345 × 10 ^-7 / ° C. or higher, according to any one of claims 1 to 3 . The wind-cooled strengthening glass according to any one of claims 1 to 4, wherein the bending point of the glass exceeds 600 ° C. and is 750 ° C. or lower. The air-cooled strengthening glass according to any one of claims 1 to 5 , wherein the Fe ³⁺ content is 6.0% by mass or less in terms of Fe ₂ O ₃ . The air-cooled strengthening glass according to any one of claims 1 to 6 , wherein the Fe ²⁺ content is 0.05% by mass or more in terms of Fe ₂ O ₃ . In terms of oxide-based mass% display,
SiO ₂ 66-75%,
Al ₂ O _{30 to} 15%,
B ₂ O ₃ 0~20%,
MgO + CaO + SrO + BaO 1-30%,
Li ₂ O + Na ₂ O + K ₂ O 1-25%
The wind-cooled strengthening glass according to any one of claims 1 to 7 , which comprises. A wind-cooled tempered glass obtained by wind-cooling the wind-cooled tempered glass according to any one of claims 1 to 8 . The air-cooled tempered glass according to claim 9 , wherein the surface compressive stress value is 60 MPa or more. The air-cooled tempered glass according to claim 9 or 10 , which has a thickness of 2.5 mm or less. The air-cooled tempered glass according to any one of claims 9 to 11 , which is used for automobile applications. The air-cooled tempered glass according to any one of claims 9 to 11 , which is used for construction purposes. The air-cooled tempered glass according to any one of claims 9 to 11 , which is used for a solar cell module. The air cooling enhancement according to any one of claims 9 to 11 , which is used for the back plate of a solar cell module and has an ISO-9050 (2003) defined visible light transmittance (D65 light source) Tv_D65 of 82% or less. Glass.

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