CN106673422A - Glass for air-quench tempering and air-quenched tempered glass - Google Patents

Abstract

The present invention provides a glass for air-cooling strengthening capable of imparting sufficient residual stress by air-cooling strengthening even in the case of thin glass having a thickness of 2.5 mm or less. In the glass for air cooling tempering, the Fe ³⁺ content is 0.8 mass % or more and less than 2.2 mass % in terms of Fe ₂ O ₃ , the Fe ²⁺ content is 0.45 mass % or less in terms of Fe ₂ O ₃ , Fe-Redox The value of 20% or less, the average coefficient of thermal expansion α _50-350 at 50-350°C is 75×10 ^-7 /°C or more and 90×10 ^-7 /°C or less, and the glass transition temperature is 500°C or more and 600°C or less , the maximum value α _max of the thermal expansion coefficient between the glass transition temperature and the yield point is 410×10 ^-7 /°C or more.

Description

Air-cooled tempered glass and air-cooled tempered glass

technical field

The present invention relates to a glass for air-cooling strengthening capable of imparting sufficient residual stress by air-cooling strengthening even in the case of thin glass having a thickness of 2.5 mm or less.

Moreover, this invention relates to the air-cooled tempered glass obtained by air-cooling tempering the glass for air-cooling tempering of this invention.

Background technique

Tempered glass is glass that has been improved from the technical problem of ordinary glass, that is, the defect that it is easy to break, and is used in vehicles, buildings, etc. Examples of vehicles include passenger cars, trucks, buses, railways, ships, and aircraft, and tempered glass is used for windows, headlights, taillights, and the like. Moreover, as a building, a building, a house, etc. are mentioned, and tempered glass is used for a door, a partition, etc. In addition, it is widely used in furniture such as bookshelves and display cabinets, electrical products such as cooking utensils, and office supplies.

Strengthened glass is produced by, for example, a method called heat strengthening. In thermal strengthening, the glass is heated to a temperature near the softening point or the yield point by utilizing the thermal contraction of the glass during cooling, and then cooled. At this time, since the surface temperature drops faster than the internal temperature drop, a temperature difference occurs in the thickness direction, tensile stress occurs on the surface and compressive stress occurs inside, and the stress relaxation phenomenon is reversed based on the subsequent stress relaxation. Compressive stress is generated on the surface and tensile stress is generated inside and remains. Since compressive stress remains on the surface, the strength is improved, and furthermore, progress of damage is suppressed, and scratch resistance is improved. As thermal strengthening, air-cooling strengthening in which plate-shaped glass is produced by a float process or the like, the cut glass plate is heated to a temperature near the softening point or yield point, and then quenched by spraying a cooling medium on the surface.

In recent years, reduction in weight of tempered glass used in vehicles, buildings, and the like has been demanded. Reinforced glass can be reduced in weight by reducing its thickness. For example, it is required to reduce the thickness to 2.5 mm or less. However, since thermal strengthening utilizes the temperature difference between the surface and the interior during cooling, if the thickness is reduced, the temperature difference between the surface and the interior cannot be increased, making it difficult to achieve true strengthening.

As a method for producing thin tempered glass, it is known to use, for example, a glass composition having a predetermined glass composition and an average coefficient of linear expansion at 50 to 350°C of 80 to 110×10 ^-7 /°C (for example, refer to Patent Document 1 ).

However, since such a manufacturing method can only control the average linear expansion coefficient at the low temperature side, it is not always possible to effectively impart residual stress to thin glass having a thickness of 2.5 mm or less.

In addition, as in the solar cell module described in Patent Document 2, in a solar cell module having a structure in which both surfaces are sandwiched by glass, the weight of the glass substrate accounts for most of the weight of the module, so the glass substrate is made thinner and lighter. The benefits are huge. Therefore, glass substrates made of chemically strengthened glass are used as the light-receiving panel and the back panel. This is because chemically strengthened glass can provide sufficient residual stress even if the thickness is 2.5 mm or less.

However, chemically strengthened glass is more expensive than air-cooled strengthened glass, so the solar cell module described in Patent Document 2 that uses chemically strengthened glass for the light-receiving panel and the back panel is expensive.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2003-119048

Patent Document 2: Japanese Patent Laid-Open No. 2013-247238

Contents of the invention

The technical problem to be solved by the invention

The present invention was made in view of the above-mentioned technical problems, and its object is to provide a glass for air-cooling strengthening that can impart sufficient residual stress by air-cooling strengthening even when it is made into a thin glass with a thickness of 2.5 mm or less. Glass, and air-cooled tempered glass obtained by air-cooling tempered glass.

Technical solutions adopted to solve technical problems

In order to achieve the above objects, the present invention provides an air-cooled strengthened glass, wherein the Fe ³⁺ content is 0.8 mass % or more and less than 2.2 mass _{% in terms of Fe 2 O 3 , and} the Fe ²⁺ content is The conversion is 0.45% by mass or less, the value of Fe-Redox is 20% or less, and the average thermal expansion coefficient α _{50 to 350} at 50 to 350°C is 75×10 ^-7 /°C or more and 90×10 ^-7 /°C or less, The glass transition temperature is not less than 500°C and not more than 600°C, and the maximum value α _max of the thermal expansion coefficient between the glass transition temperature and the yield point is not less than 410×10 ^-7 /°C.

In the air-cooled tempering glass of the present invention, expressed in mass % based on oxides, it is preferable to contain:

Moreover, this invention provides the air-cooled tempered glass obtained by air-cooling tempering the glass for air-cooling tempering of this invention.

The air-cooled tempered glass of the present invention preferably has a surface compressive stress value of 60 MPa or more.

The air-cooled tempered glass of the present invention preferably has a thickness of 2.5 mm or less.

The air-cooled tempered glass of the present invention is preferably used for automobiles.

The air-cooled tempered glass of the present invention is preferably used in construction.

The air-cooled tempered glass of the present invention is preferably used for a solar cell module.

Invention effect

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, sufficient residual stress can be imparted by air cooling strengthening.

Description of drawings

FIG. 1 is a plan view of a portion of an air-cooling strengthening device used in an example where a cooling nozzle is installed.

detailed description

Hereinafter, the glass for air cooling strengthening of this invention is demonstrated.

The glass transition temperature of the glass for air cooling strengthening of this invention is 500 degreeC or more. As mentioned above, in the air-cooling tempering treatment, after the glass plate is produced by the float process or the like, the cut glass plate is heated to a temperature near the softening point or the yield point, and then the surface is quenched by spraying a cooling medium to impart As for the glass residual stress, when the glass transition temperature is lower than 500° C., it is difficult to cause a temperature difference between the surface and the inside through the above-mentioned heating step and cooling step, and the residual stress cannot be effectively imparted. The glass transition temperature is preferably 530°C or higher, more preferably 540°C or higher. Moreover, it is preferable that the upper limit of the temperature at the time of a heating process is glass transition temperature+200 degreeC. If the upper limit of the temperature in the heating step is higher than the glass transition temperature + 200° C., the glass is liable to viscous flow deformation at high temperatures, and the optical quality of the final strengthened glass may deteriorate.

On the other hand, if the glass transition temperature is too high, it needs to be heated to a high temperature in the heating process, and the surrounding members for holding the glass are exposed to high temperature, so their life may be significantly reduced. In order to prolong the life, it is necessary to use durable An expensive component with excellent thermal properties. Therefore, the glass transition temperature is set to be 600° C. or lower. The glass transition temperature is preferably 590°C or lower, more preferably 580°C or lower.

In the glass for air cooling strengthening of the present invention, the maximum value α _max of the thermal expansion coefficient between the glass transition temperature and the yield point (hereinafter referred to as "high temperature thermal expansion coefficient α _max " in this specification) is 410×10 ^-7 /°C above. When the high-temperature thermal expansion coefficient α _max is lower than 410×10 ^-7 /°C, it may not be possible to effectively impart residual stress using a normal air-cooling tempering device in the case of thin glass having a thickness of 2.5 mm or less. Usually, air-cooling strengthening is implemented by rapid cooling from the temperature higher about 100 degreeC than a glass transition temperature. By setting the high-temperature thermal expansion coefficient α _max to 410×10 ^-7 /°C or higher, even in the case of thin glass with a thickness of 2.5mm or less, it is effective to use a normal air-cooling strengthening device from the above temperature. to impart residual stress.

Here, the high-temperature thermal expansion coefficient α _max refers to the maximum value of the thermal expansion coefficient between the glass transition temperature and the yield point in the expansion coefficient curve of the treated glass measured with a thermal dilatometer as described below. From the viewpoint of imparting residual stress, the higher the high-temperature thermal expansion coefficient α _max , the better, but generally 600×10 ^-7 /°C is sufficient. In addition, if the high-temperature thermal expansion coefficient α _max increases, the glass may break due to temporary deformation at the initial stage of cooling, and the yield may deteriorate. Therefore, the high-temperature thermal expansion coefficient α _max is preferably 410×10 ^-7 /°C or more and 600 ×10 ^-7 /℃ or less.

The yield point of the glass for air cooling strengthening of the present invention is not necessarily limited, but is preferably higher than 600°C. When the yield point is 600° C. or lower, 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 imparted. The yield point is preferably 750°C or lower. If the yield point exceeds 750°C, it needs to be heated to a high temperature, and the surrounding members for holding the glass are exposed to high temperature, so their life may be significantly reduced. In order to prolong the life, it is necessary to use expensive members with excellent heat resistance. The yield point of the glass for air cooling strengthening of the present invention is more preferably 700° C. or lower.

From the viewpoint of imparting residual stress, the average coefficient of thermal expansion α _{50 to 350} at 50 to 350° C. of the glass for air cooling tempering of the present invention is preferably as large as possible. The expansion mismatch problem, or the resistance to thermal shock becomes weak. Therefore, the average coefficient of thermal expansion α _{50 to 350} at 50 to 350°C of the glass for air cooling strengthening of the present invention is 75×10 ^-7 /°C or higher, more preferably 77×10 ^-7 /°C or higher, and still more preferably 79×10 -7 /°C or higher. Above 10 ^-7 /℃. On the other hand, the average coefficient of thermal expansion α _{50 to 350} at 50 to 350°C of the glass for air cooling tempering of the present invention is 110×10 ^-7 /°C or less, more preferably 100×10 ^-7 /°C or less, still more preferably Below 95×10 ^-7 /℃.

The thermal expansion coefficient difference between the high-temperature thermal expansion coefficient α _max and the average thermal expansion coefficient α _{50 to 350} at 50 to 350° C. (Δα (=α _max −α _{50 to 350} )) of the glass for air cooling strengthening of the present invention is preferably 345×10 ^-7 /°C or more. When simply increasing the thermal expansion coefficient from low temperature to high temperature, that is, the high temperature thermal expansion coefficient α _max and the average linear expansion coefficient α _{50 to 350} at 50 to 350°C, it is easy to cause thermal shock during the heating process and cooling process. The rupture, the mismatch with the thermal expansion of other components, the incompatibility with the current process, etc.

By making the thermal expansion coefficient difference (Δα) 345×10 ^-7 /°C or more, that is, by setting the average thermal expansion coefficient α _{50 to 350} at 50 to 350°C as a constant value, the high temperature thermal expansion coefficient is relatively increased For α _max , even in the case of thin glass with a thickness of 2.5 mm or less, residual stress can be effectively imparted by a normal air-cooled tempering device, and the occurrence of cracks due to thermal shock can be suppressed. The thermal expansion coefficient difference (Δα) is more preferably 360×10 ^-7 /°C or higher, and still more preferably 370×10 ^-7 /°C or higher. Regarding the thermal expansion coefficient difference (Δα), basically the larger the better, but generally 500×10 ^-7 /°C is sufficient.

Here, the glass transition temperature, yield point, and coefficient of thermal expansion (α _max , α _{50 to 350} ) were measured in the following manner. That is, a cylindrical sample with a diameter of 5 mm and a length of 20 mm was prepared, and the thermal expansion was measured using a thermal dilatometer at a heating rate of 5° C./min. under a load of 10 g, and the glass transition temperature, yield point, and coefficient of thermal expansion (α _max , α _50～350 ).

With regard to air-cooled strengthened glass, because it utilizes the temperature difference between the surface and the inside generated by performing the above-mentioned heating process and cooling process, if the thickness is reduced, the temperature difference between the surface and the inside cannot be increased, and it is difficult to provide sufficient temperature. Residual Stress. Regarding this point, the inventors of the present application conducted earnest research and found that the trivalent iron (Fe ³⁺ ) content, divalent iron (Fe ²⁺ ) content, and Fe-Redox content of the glass for air-cooling strengthening When the value satisfies specific conditions, α _max can be increased, and as a result, the residual stress of the air-cooled strengthened glass increases.

In the glass for air-cooling tempering of the present invention, by setting the Fe ³⁺ content to 0.8 mass % or more and less than 2.2 mass % in terms of Fe ₂ O ₃ , even when it is a thin glass with a thickness of 2.5 mm or less , residual stress can also be effectively imparted using a common air-cooling strengthening device. When the Fe ³⁺ content is less than 0.8% by mass in terms of Fe ₂ O ₃ , it may not be possible to effectively impart residual stress using a normal air-cooling strengthening device in the case of thin glass having a thickness of 2.5 mm or less. When the Fe ³⁺ content is 2.2% by mass or more in terms of Fe ₂ O ₃ , it becomes yellowish and the appearance deteriorates, which is not preferable.

In the glass for air cooling tempering of the present invention, the Fe ³⁺ content is preferably 0.9% by mass to 2.1% by mass, more preferably 1.0% by mass to 2.0% by mass, in terms of Fe ₂ O ₃ .

In the glass for air-cooling strengthening of this invention, Fe2 ⁺ content is 0.45 mass % or less in conversion _{of Fe2O3} . If the Fe ²⁺ content is higher than 0.45% by mass in terms of Fe ₂ O ₃ , the temperature of the melting furnace will decrease, and the meltability of the glass will decrease.

In the glass for air cooling tempering of the present invention, the Fe ²⁺ content is preferably 0.43% by mass or less, more preferably 0.41% by mass or less, in terms of Fe ₂ O ₃ .

In the glass for air cooling strengthening of the present invention, the Fe-Redox value is 20% or less. Here, Fe-Redox refers to the ratio of the Fe ²⁺ content in terms of Fe ₂ O ₃ to the total iron content in terms of Fe ₂ O ₃ . If the value of Fe-Redox is more than 20%, there is a problem of color change during long-term use because exposure to sunlight (Japanese: ソラリゼーション) occurs, resulting in a color change.

The glass for air-cooling tempering of the present invention preferably has a Fe-Redox value of 16% or less, more preferably 13% or less, and still more preferably 10% or less.

In the air-cooled tempering glass of the present invention, expressed in mass % based on oxides, it is preferable to contain:

Hereinafter, the mass % based on an oxide is simply expressed as %.

If such a composition is adopted, since it has substantially the same constituent components as soda lime glass generally used in the manufacture of strengthened glass, productivity is good. In addition, with this composition, glass having a glass transition temperature of 500°C to 600°C and a high-temperature thermal expansion coefficient α _max of 410×10 ^-7 /°C or higher can be obtained. The range of the composition of each component is demonstrated below.

The content of SiO ₂ is preferably not less than 66% and not more than 75%. If it is less than 66%, disadvantages such as increase in density of glass, increase in thermal expansion coefficient, and deterioration in scratch resistance will occur. The content of SiO ₂ is preferably 67% or more, more preferably 68% or more. In addition, if the content of SiO ₂ exceeds 75%, the viscosity will increase and the glass will be difficult to melt. The content of SiO ₂ is preferably 73% or less.

Al ₂ O ₃ may be contained as needed, and its content is less than 15%. If the content of Al ₂ O ₃ exceeds 15%, the thermal expansion coefficient at the glass transition temperature or higher may not easily 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 may be contained as required, and its content is below 20%. When the content of B ₂ O ₃ exceeds 20%, the coefficient of thermal expansion at the glass transition temperature or higher may become difficult 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 (MgO+CaO+SrO+BaO) of alkaline earth metal oxides, that is, MgO, CaO, SrO, and BaO is 1% or more. If MgO+CaO+SrO+BaO is less than 1%, it is necessary to add a large amount of alkali metal oxides, that is, Li ₂ O, Na ₂ O, and K ₂ O, in order to maintain the meltability of the glass at a high temperature and a moderate thermal expansion coefficient. As a result, there is a possibility that the temperature difference between the deformation point and the yield point becomes smaller, and the residual stress becomes smaller. MgO+CaO+SrO+BaO is preferably 3% or more, more preferably 5% or more, and still more preferably 10% or more. MgO+CaO+SrO+BaO is preferably 30% or less. If it exceeds 30%, the tendency of devitrification of glass will increase and productivity will deteriorate. MgO+CaO+SrO+BaO is preferably 25% or less.

The content of MgO is 0.1% or more. MgO is an essential component for maintaining a moderate thermal expansion coefficient, and can also improve scratch resistance. The content of MgO is preferably 2% or more, more preferably 3% or more. In addition, the content of MgO is 25% or less. When the content of MgO exceeds 25%, the tendency of devitrification of glass will increase and productivity will deteriorate. The content of MgO is preferably 23% or less, more preferably 21% or less, further preferably 20% or less.

The content of CaO is 0.1% or more. CaO is an essential component in order to maintain the thermal expansion coefficient of glass moderately. The content of CaO is preferably 2% or more, more preferably 3% or more. The content of CaO is 15% or less. When the content of CaO exceeds 15%, the tendency of devitrification of glass will increase, and productivity will deteriorate. The content of CaO is preferably 14% or less, more preferably 13% or less.

SrO may be contained as needed, and its content is 10% or less. By containing SrO, the meltability and thermal expansion coefficient of glass at high temperature can be adjusted. If the content of SrO exceeds 10%, the density of glass will increase and the weight of glass will increase. 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 its content is below 10%. By containing BaO, the meltability and thermal expansion coefficient of glass at high temperature can be adjusted. On the other hand, if BaO is contained, the density of the glass increases, so the weight of the glass tends to increase. In addition, when BaO is contained, the glass becomes brittle, so the crack cracking load (Japanese: crack, iniciaersion, and rod) becomes low, and it is easy to be damaged. Therefore, the content of BaO is 7% or less, preferably 5% or less, more preferably 3% or less.

The total content (Li ₂ O+Na ₂ O+K ₂ O) of alkali metal oxides, that is, Li ₂ O, Na ₂ O, and K ₂ O is 1% or more. If Li ₂ O+Na ₂ O+K ₂ O is less than 1%, it is necessary to add a large amount of alkaline earth metal oxides, that is, MgO, CaO, SrO, and BaO, in order to maintain the meltability of the glass at high temperature and a moderate thermal expansion coefficient. As a result, the devitrification tendency of glass increases and productivity deteriorates. Li ₂ O+Na ₂ O+K ₂ O is preferably 3% or more, more preferably 5% or more, further preferably 8% or more, 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 deformation point and the yield point may become smaller, and the residual stress may become smaller. Li ₂ O+Na ₂ O+K ₂ O is preferably 25% or less, more preferably 20% or less.

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

K ₂ O may be contained as needed, and its content is preferably 0.1% or more. When the content of K ₂ O is 0.1% or more, the high-temperature meltability and moderate thermal expansion coefficient of the glass can be maintained. The content of K ₂ O is more preferably 0.5% or more, particularly preferably 1% or more. The content of K ₂ O is 4% or less. If the content of K ₂ O 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 tempering glass of the present invention is preferably substantially composed of the above-mentioned components, and may contain other components not exceeding 10% in total as needed and within the limit not violating the technical idea of the present invention. As another component, ZrO2, _Y2O3 , _CeO2 , _MnO , _CoO etc. are mentioned, for example. Moreover, although PbO etc. may be contained, it is preferable not to contain these components substantially. In addition, substantially not containing means that it is less than 0.01%.

In addition, SO ₃ , chlorides, fluorides, halogens, SnO ₂ , Sb ₂ O ₃ , As ₂ O ₃ , and the like can be appropriately contained as clarifiers at the time of glass melting. In addition, Ni, Cr, V, Se, Au, Ag, Cd, etc. may be contained in order to adjust the color tone. The glass to be treated preferably does not substantially contain As, Sb, or Pb. Since these components are toxic, it is preferable not to contain these components in glass in order to prevent influence on the environment. In addition, substantially not containing means that it is less than 0.01%.

Even when the glass for air-cooling tempering of the present invention is thin glass having a thickness of 2.5 mm or less, residual stress can be effectively imparted using a general air-cooling tempering device, so that the weight of the glass can be reduced. From the viewpoint of weight reduction, the thickness is preferably 2.4 mm or less, more preferably 2.3 mm or less, further preferably 2.0 mm or less, 1.5 mm or less, and 1.3 mm or less. However, from the viewpoint of effectively imparting residual stress, the plate thickness is preferably 0.5 mm or more, more preferably 0.7 mm or more.

The glass for air-cooling tempering of the present invention can be produced by any of glass sheet forming methods such as the float method, the fusion method, the down-draw method, and the roll method. The use of the float method is preferable because it is easy to produce a large-area glass plate and to reduce thickness variations.

Even when the glass for air-cooling tempering of the present invention is a thin glass having a thickness of 2.5 mm or less, residual stress can be effectively imparted using a general air-cooling tempering device. In the case of thin glass having a thickness of 2.5 mm or less, the surface compressive stress value of the air-cooled strengthened glass is preferably 110 MPa or more, more preferably 122 MPa or more, and still more preferably 130 MPa or more.

In the case of thin glass having a thickness of 2.0 mm or less, the surface compressive stress value of the air-cooled tempered glass is preferably 70 MPa or more, more preferably 78 MPa or more, and still more preferably 85 MPa or more.

In the case of thin glass having a thickness of 1.5 mm or less, the surface compressive stress value of the air-cooled tempered glass is preferably 60 MPa or more, more preferably 65 MPa or more, and still more preferably 70 MPa or more.

The air-cooled tempered glass of the present invention is an air-cooled tempered glass obtained by air-cooling tempering the glass for air-cooling tempering 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 characteristics of the above-mentioned 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. When the thickness is 2.5 mm or less, the surface compressive stress value is preferably 110 MPa or more, more preferably 122 MPa or more, and still 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 still more 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, and still more preferably 70 MPa or more.

The air-cooled tempered glass of the present invention is preferably used in various applications in which tempered glass can be used. Specifically, it is preferably used for automobile use and construction use. In addition, it can be preferably used as a light-receiving panel or a back panel of a solar cell module.

When used as a back plate of a solar cell module, if the transparency of the air-cooled tempered glass is high, wiring and the like can be seen, degrading designability. The air-cooled tempered glass has a visible light transmittance (D65 light source) Tv_D65 specified in ISO-9050 (2003) of preferably 82% or less, more preferably 80% or less, and still more preferably 77% or less in order to improve designability.

Example

The present invention is further illustrated by the following examples.

Under the conditions of forming the glass composition shown in Table 1, properly select the commonly used glass raw materials such as oxides, put the mixture into a platinum crucible, and put it into a resistance heating electric furnace at 1600 ° C, melt for 3 hours, and perform degassing , After homogenization, pour it into the mold material, keep it at a temperature about 30°C higher than the glass transition temperature for more than 1 hour, then anneal it to room temperature at a cooling rate of 0.3-1°C per minute, and make Examples 1-5 , The plate-shaped glass samples of Comparative Examples 1-6.

With respect to the obtained glass sample, Fe-Redox was calculated using the following formula (1) from the spectrum curve of the glass sample measured by the spectrophotometer.

Fe-Redox (%)=-log _e (T _1000nm /91.4)/(Fe ₂ O ₃ amount×t×20.79)×100 (1).

in,

T _1000nm is the transmittance (%) at a wavelength of 1000nm measured by a spectrophotometer (manufactured by Perkin Elmer, Lambda950);

t is the thickness (cm) of the glass sample;

The amount of Fe ₂ O ₃ is the total iron content (%=mass %) in terms of Fe ₂ O ₃ obtained by fluorescent X-ray measurement.

The above-mentioned Fe-Redox adopts the method calculated according to the spectrogram curve of the glass sample measured by a spectrophotometer, and its value can be regarded as equal to the Fe2 ⁺ content in the same glass in terms _{of Fe2O3} and Fe2 ₊ The ratio of total iron content calculated in O ₃ conversion.

Next, according to the standard of JIS R 3103-3:2001, a cylindrical sample with a diameter of 5 mm and a length of 20 mm was made from the glass sample, and a thermal dilatometer (TMA4000SA, manufactured by Bruker AXS Co., Ltd.) was used at 5 Thermal expansion was measured at a temperature increase rate of °C/min and a load of 10 g, and the glass transition temperature (Tg) was calculated.

In addition, according to the standard of JIS R 1618:2002, for the glass to be treated, thermal expansion was measured at a heating rate of 5° C./min using a thermal dilatometer (manufactured by Bruker AXS, TMA4000SA) in the same manner as the measurement of the glass transition temperature, and 50 to 50°C were calculated. Average thermal expansion coefficient α _{50 to 350} at 350°C, and high temperature thermal expansion coefficient α _max .

In addition, the visible light transmittance (for Tv_D65, a spectrophotometer (manufactured by PerkinElmer, Lambda 950) was used for measurement.

In addition, for the glass samples of Examples 1-5 and Comparative Examples 1-6, in order to evaluate the handling easiness of air-cooling strengthening, the surface residual stress after air-cooling strengthening was measured by the method shown below.

The glass sample was cut to a size of 550 mm×550 mm, and chamfered. In the air-cooling strengthening treatment, common roll-transfer-type air-cooling strengthening equipment is used. Fig. 1 is a plan view of the part where the cooling nozzle is installed in the air-cooling strengthening equipment, and the left side of the figure shows the shape of the end surface of the part where the cooling nozzle is installed. As shown in FIG. 1 , a plurality of cooling nozzles 20 , 30 , and 40 are arranged in different heights. The nozzle 20 is installed so as to be perpendicular to the surface to be processed of the glass plate to be processed. The diameter of the nozzles 20 is 3.1 mm, and the pitch between the nozzles 20 is 24 mm. The nozzles 30 and 40 are installed obliquely toward the surface to be processed of the glass plate to be processed. The diameters of the nozzles 30 and 40 are each 3.9 mm, and the pitch between the nozzles 30 and the pitch between the nozzles 40 are each 24 mm. With respect to the nozzle 30, the distance from the nearest nozzle 20 and the distance from the nearest nozzle 40 were each 8 mm. The distance between the nozzle 20 and the surface to be processed of the glass plate to be processed was 10 mm. The temperature of the air supplied from the nozzles 20, 30, and 40 as a cooling medium is 60°C, and the wind pressure (injection port wind pressure) is 18-19kPa. From the state where the glass plate to be processed is heated to 630-635°C, the glass to be processed The surface of the plate to be processed is cooled by spraying air as a cooling medium. The surface compressive stress value of the air-cooled tempered glass thus produced was measured using a glass surface stress meter (FSM-7000H manufactured by Orihara Seisakusho). The surface compressive stress value of each sample was divided by the surface compressive stress value of Comparative Example 5, and the obtained value was defined as the relative surface compressive stress value.

[Table 1]

The Fe ³⁺ content is 0.8% by mass or more and less than 2.2% by mass in terms of Fe ₂ O ₃ , the Fe ²⁺ content is 0.45% by mass or less in terms of Fe ₂ O ₃ , and the Fe-Redox value is 20% or less The high-temperature thermal expansion coefficient α _max of the glasses of Examples 1 to 5 was 410×10 ^-7 /°C or higher, and the relative surface compressive stress value of the glass after air-cooling strengthening was 1.1 or higher. The high temperature of the glasses of Comparative Examples 1 and 2 that do not contain Fe ₂ O ₃ and the glasses of Comparative Examples 3 to 6 whose Fe ³⁺ content is less than 0.8% by mass in terms of Fe ₂ O ₃ and whose Fe-Redox value exceeds 20% The thermal expansion coefficient α _max is lower than 410×10 ^-7 /°C, and the relative surface compressive stress value of the air-cooled strengthened glass is lower than 1.1.

Symbol Description

20, 30, 40 nozzles

Claims (9)

1. Glass for air-cooled strengthening, wherein Fe³⁺In the content of Fe₂O₃0.8 mass% or more and less than 2.2 mass% in terms of Fe²⁺In the content of Fe₂O₃0.45% by mass or less in terms of Fe-Redox value, 20% or less in Fe-Redox value, and α which is an average thermal expansion coefficient at 50 to 350 DEG C_50～350Is 75 × 10^-7over/deg.C and 110 × 10^-7A glass transition temperature of 500 ℃ to 600 ℃ inclusive, and a maximum value α of a coefficient of thermal expansion between the glass transition temperature and a yield point of not higher than/° C_maxIs 410 × 10^-7at/DEG C toThe above.

2. The air-cooled tempering glass according to claim 1, comprising, in mass% on an oxide basis:

3. an air-cooled tempered glass obtained by air-cooling tempering the glass for air-cooled tempering according to claim 1 or 2.

4. The air-cooled tempered glass according to claim 3, wherein the surface compressive stress value is 60MPa or more.

5. The air-cooled tempered glass of claim 3 or 4 having a thickness of 2.5mm or less.

6. The air-cooled tempered glass of any one of claims 3 to 5, wherein the glass is used for automotive applications.

7. The air-cooled tempered glass of any one of claims 3 to 5, wherein the glass is used for architectural purposes.

8. The air-cooled tempered glass according to any one of claims 3 to 5, wherein the glass is used for a solar cell module.

9. The air-cooled tempered glass according to any one of claims 3 to 5, wherein the glass is used for a back panel of a solar cell module, and has a visible light transmittance (D65 light source) Tv _ D65 of 82% or less as defined in ISO-9050 (2003).