double-glazed windows

Abstract

To provide a double glass with a low radiation film capable of stabilizing fireproof performance.SOLUTION: A double glass includes a plurality of glass plates with a spacer interposed therebetween, and a circumferential edge part sealed with a sealing material. At least one of the plurality of glass plates is a glass with a low radiation film that includes a low radiation film whose emissivity is 0.12 or less. At least one of the plurality of glass plates other than the glass with the low radiation film is a chemically strengthened glass. A surface compressive stress CS of the chemically strengthened glass is 340 MPa or more. A depth of a compressive stress layer DOL of the chemically strengthened glass is 20-50 μm. A plate thickness of the chemically strengthened glass is 2-10 mm. A plurality of glass plates are soda lime glasses.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to double-glazed glass, and more particularly to double-glazed glass with a low-emissivity coating that has fire-resistant properties. [Background technology]

[0002] Traditionally, fire-resistant glass required for purposes such as preventing the spread of fire has included wired glass, which prevents openings from being created when the glass breaks and falls out during a fire; heat-resistant tempered glass, which is made less prone to breakage by forming surface compressive stress on the glass surface using an air-cooling strengthening method, thereby withstanding the tensile stress (thermal stress) generated by the temperature difference between the inside of the glass surface and the edge covered by the sash during a fire; and transparent crystallized glass.

[0003] To address issues such as the increased thickness of wired glass, the insufficient fire resistance of air-cooled tempered glass unless it is thick enough, and the reduced strength of transparent crystallized glass due to cracking, it has been proposed that at least one of the double-glazed panes of glass be chemically strengthened, in which at least two panes of glass are separated by a spacer and the edges are sealed with a sealant (Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-218422 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, the double-glazed glass described in Patent Document 1 was not sufficient to stabilize the fire resistance performance. Furthermore, when the glass with the low-emissivity coating was placed on the non-heated side, the low-emissivity coating reflected heat, causing the glass on the heated side to heat up more intensely, thus preventing the fire resistance performance from stabilizing.

[0006] This invention has been made in view of these circumstances, and aims to provide double-glazed glass with a low-emissivity coating that can stabilize fire resistance. [Means for solving the problem]

[0007] One embodiment of the present invention is a double-glazed glass comprising a plurality of glass plates separated by spacers and sealed at their periphery with a sealing material, wherein at least one of the plurality of glass plates is a low-emissivity glass with a low-emissivity film of 0.12 or less, at least one of the plurality of glass plates other than the low-emissivity glass is a chemically strengthened glass, the surface compressive stress CS of the chemically strengthened glass is 340 MPa or more, the depth DOL of the compressive stress layer of the chemically strengthened glass is 20 μm or more and 50 μm or less, the thickness of the chemically strengthened glass is 2 mm or more and 10 mm or less, and the plurality of glass plates are soda-lime glass.

[0008] Chemically strengthened glass used in double-glazed windows may also have a curvature of 0.25% or less, as specified in JIS R3206 (2003).

[0009] The low-emissivity glass of any of the above double-glazed glass types may have a curvature of 0.25% or less as defined in JIS R3206 (2003).

[0010] The edge strength of the chemically strengthened glass in any of the above double-glazed windows may be 260 MPa or more at a stress corresponding to a logarithmic 0.1% probability of fracture.

[0011] The chemically strengthened glass of any of the above double-glazed glass may have a minimum edge strength fracture stress of 300 MPa or higher.

[0012] The chemically strengthened glass in any of the above double-glazed glass types may have an average fracture stress value of 360 MPa or higher at its edge strength.

[0013] The chemically strengthened glass in any of the above double-glazed glass types may have a latent scratch depth of 20 μm or less at its edge.

[0014] For the chemically strengthened glass of any of the above multilayer glasses, the ratio of the depth of the latent flaw to the depth of the compressive stress layer (DOL) may be 95% or less.

Advantages of the Invention

[0015] According to the multilayer glass of the present invention, the fireproof performance can be stabilized.

Brief Description of the Drawings

[0016] [Figure 1] FIG. 1 is a cross-sectional view of a multilayer glass according to an embodiment. [Figure 2] FIG. 2 is a diagram for explaining the measurement position of the warp of the chemically strengthened glass. [Figure 3] FIG. 3 is a diagram showing a grid board used in the grid board method evaluation. [Figure 4] FIG. 4 is a diagram showing an evaluation example by the grid board method. [Figure 5] FIG. 5 is a schematic diagram showing an example of a test jig for measuring the edge strength. [Figure 6] FIG. 6 is a diagram for explaining a method of cutting four glass plates from the glass after chemical strengthening.

Modes for Carrying Out the Invention

[0017] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is described by the following preferred embodiments. Without departing from the scope of the present invention, various modifications can be made by many methods, and other embodiments other than the present embodiment can be used. Therefore, all modifications within the scope of the present invention are included in the claims.

[0018] Here, in the drawings, parts denoted by the same reference numerals are the same elements having the same functions. Also, in this specification, when a numerical range is represented using "~", the upper and lower limit numerical values indicated by "~" are also included in the numerical range.

[0019] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0020] Figure 1 is a cross-sectional view of a double-glazed window. As shown in Figure 1, the double-glazed window 10 comprises two glass plates 12A and 12B that are separated from each other at a certain distance apart, and a spacer 16 that separates the two glass plates 12A and 12B.

[0021] The two glass plates 12A and 12B are, for example, each configured in a rectangular shape. Glass plate 12A has two opposing main surfaces and four end surfaces. Similarly, glass plate 12B has two opposing main surfaces and four end surfaces.

[0022] The spacer 16 is positioned along the peripheral edges of the inner main surfaces of the two glass plates 12A and 12B so that the distance between them remains constant.

[0023] The hollow layer 14 is defined by two glass plates 12A and 12B and a spacer 16. The thickness of the hollow layer 14 (the distance between the inner main surfaces of the two glass plates 12A and 12B) is determined by the size of the spacer 16 interposed between the two glass plates 12A and 12B. The thickness of the hollow layer 14 is not limited, but from the viewpoint of improving heat insulation, it is preferably 4 mm or more, more preferably 8 mm or more, more preferably 12 mm or more, and even more preferably about 16 mm. The thickness of the hollow layer 14 may be 20 mm or less. Also, the glass plates 12A and 12B are not limited to two. The double-glazed glass 10 can consist of two or more glass plates. Therefore, the double-glazed glass may consist of three glass plates or four glass plates. Multiple glass plates are separated by spacers. Furthermore, the three or more glass plates may be double-glazed glass composed of laminated glass and glass plates separated from the laminated glass.

[0024] As shown in Figure 1, the double-glazed glass 10 has a configuration in which glass plates 12A and 12B are separated by a spacer 16, and the peripheral edges are sealed with sealing material (primary sealing material 18A and 18B and secondary sealing material 20).

[0025] The spacer 16 has surfaces facing the glass plates 12A and 12B that are bonded to the inner main surfaces of the glass plates 12A and 12B by primary sealing materials 18A and 18B. A concave space is formed between the outside of the spacer 16 (opposite the hollow layer 14) and the glass plates 12A and 12B. The secondary sealing material 20 is placed in this concave space so as to be in contact with the primary sealing materials 18A and 18B. The hollow layer 14 is sealed (airtight) by the secondary sealing material 20 and the primary sealing materials 18A and 18B.

[0026] The spacer 16 is formed in a hollow shape. On the inner surface of the spacer 16 (the side facing the hollow layer 14), ventilation holes 22 are formed at a constant pitch along the longitudinal direction of the spacer 16 (the direction perpendicular to the paper plane). The ventilation holes 22 are formed to penetrate the hollow portion 24 of the spacer 16, connecting the hollow portion 24 and the hollow layer 14. The hollow portion 24 of the spacer 16 is filled with a desiccant 26 such as granular zeolite. This dries the air in the hollow layer 14.

[0027] The spacer 16 may be a metal spacer mainly made of aluminum, or it may be a spacer in which the spacer body is made of a hard resin and its surface is covered with an aluminum sheet.

[0028] The primary sealants 18A and 18B are preferably based on butyl rubber or polyisobutylene that is not crosslinked, and contain fillers such as carbon black for coloring and reinforcement. Since the primary sealants 18A and 18B do not solidify and only have adhesive properties, the adhesion between the spacer 16 and the glass plates 12A and 12B in the so-called double-glazed glass 10 is ensured by the secondary sealant 20.

[0029] The secondary sealant 20 is polysulfide (manufactured by Yokohama Rubber Co., Ltd.: product name: Hamatite SM9000) and silicone (manufactured by Toray Dow Corning Co., Ltd.: product name: SE93). 6) Preferably, the material is based on a curable elastomer such as urethane (manufactured by Sanyurec Co., Ltd.: product name: SANYU IGS205) and has been modified appropriately to exhibit adhesion to glass plates 12A and 12B.

[0030] Glass plate 12B, one of the two glass plates 12A and 12B, is a low-emissivity glass plate with a low-emissivity film 28 formed on it. On the other hand, glass plate 12A, which is not glass plate 12B, is made of chemically strengthened glass. The low-emissivity film 28 is also called a Low-E (Low Emissivity) film.

[0031] Chemically strengthened glass, as applied to glass plate 12A, is glass that has been chemically treated to create a compressive stress layer on its surface and a tensile stress layer inside the glass. This strengthens the glass by forming a compressive stress layer on its surface. Chemical treatments include, for example, ion exchange. Ion exchange involves ion exchange between the surface and back of the glass plate, replacing ions with small ionic radii (e.g., lithium ions, sodium ions) with ions with larger ionic radii (e.g., potassium ions). This creates surface compressive stress (CS) in the surface and back layers of the glass plate. This surface compressive stress CS occurs across the entire surface of the glass, forming a compressive stress layer of uniform thickness across the entire surface. In ion exchange, the glass plate is immersed in a high-temperature treatment solution (e.g., molten potassium nitrate) to perform ion exchange.

[0032] The magnitude of the surface compressive stress CS on the glass surface and the depth of the compressive stress layer (DOL) formed on the glass surface can be adjusted by the chemical treatment time and chemical treatment temperature, respectively. For example, at the same chemical treatment temperature, a longer chemical treatment time results in a deeper compressive stress layer (DOL). Also, at the same chemical treatment temperature, a longer chemical treatment time initially results in a larger magnitude of surface compressive stress CS, which then decreases over time. When the chemical treatment time and chemical treatment temperature differ, there may not be a one-to-one correspondence between the compressive stress layer (DOL) and the magnitude of the surface compressive stress CS.

[0033] The glass plate 12A to which chemically strengthened glass is applied becomes less prone to cracking as the surface compressive stress CS increases. Therefore, the surface compressive stress CS of the glass plate 12A is 340 MPa or more, preferably 360 MPa or more, and more preferably 380 MPa or more. The surface compressive stress CS of the glass plate 12A may be 650 MPa or less in order to reduce manufacturing costs and ensure the depth of the compressive stress layer DOL to obtain mechanical strength.

[0034] The depth DOL of the compressive stress layer of the glass plate 12A is 20 μm or more, preferably 24 μm or more, and more preferably 28 μm or more, in order to ensure sufficient strength to withstand external forces. Furthermore, in order to ensure a sufficient surface compressive stress CS and to allow for short-term immersion in the molten salt, the depth DOL of the compressive stress layer of the glass plate 12A is 50 μm or less.

[0035] The thickness of the glass plate 12A to which chemically strengthened glass is applied is 2 mm or more and 10 mm or less, preferably 2 mm or more and 5 mm or less, and more preferably 2 mm or more and 4 mm or less. If the thickness of the glass plate 12A is 2 mm or more, the deflection of the glass plate 12A can be reduced when used as window glass. If the thickness of the glass plate 12A is 10 mm or less, compared to heat-resistant tempered glass or wired glass, the transparency of the double-glazed glass 10 as window glass can be improved by making the glass thinner, the total thickness and weight can be kept from increasing, and furthermore, when the total thickness of the double-glazed glass is constant, the thickness of the intermediate layer can be secured and the heat insulation performance can be maintained.

[0036] Of the two glass plates 12A and 12B, a low-emissivity film 28 with an emissivity of 0.12 or less is formed on glass plate 12B, which is not glass plate 12A to which chemically strengthened glass is applied. The low-emissivity film 28 is formed on the inner main surface of glass plate 12B. Emissivity is defined in accordance with the Japanese Industrial Standards. This is the value of normal emissivity as defined by JIS R3106 (2019). Thermal cracking can be suppressed by reducing the emissivity to 0.12 or less. The emissivity of the low-emissivity film 28 is more preferably 0.10 or less, and even more preferably 0.04 or less. The emissivity of the glass plate 12B on which the low-emissivity film 28 is formed can be measured using a Perkin Elmer FT / IR "Frontier Gold" infrared spectrometer.

[0037] The low-emissivity film 28 may be a low-emissivity film mainly composed of silver (Ag) deposited using a sputtering apparatus or the like, or a low-emissivity film mainly composed of tin oxide (SnO2) deposited using a chemical vapor deposition apparatus or a sputtering apparatus or the like.

[0038] Low-emissivity films primarily composed of silver (Ag) also include types in which a silver film is laminated with oxide films, nitride films, etc. Since low-emissivity films primarily composed of silver are easily oxidized by moisture in the air, etc., when used in double-glazed glass 10, it is preferable to form the film on the inner main surface of the glass plate 12B facing the sealed hollow layer 14.

[0039] As the glass plate 12B on which the low-emissivity film 28 is formed, for example, architectural soda-lime glass can be used. The glass plate 12B is a flat piece of glass (including cut glass) obtained by the glass manufacturing process, and may be glass that has not undergone chemical strengthening treatment, or glass that has undergone chemical strengthening treatment.

[0040] The thickness of the glass plate 12B is preferably in the range of 1 mm to 20 mm, and more preferably 2 mm to 12 mm. The glass forming the low-emissivity film applied to the glass plate 12B does not necessarily need to guarantee fire resistance. The glass applied to the glass plate 12B may be chemically strengthened glass and have fire resistance. The multiple glass plates applied to the double-glazed glass 10, in this case two glass plates 12A and 12B, are made of soda-lime glass.

[0041] Soda-lime glass preferably contains, for example, 65-76% SiO2, 0.2-3% Al2O3, 10-16% Na2O, 0-2% K2O, 2-12% MgO, and 5-15% CaO, expressed as molar percentages based on oxides. Hereafter, unless otherwise specified, percentages indicate the content as molar percentages based on oxides.

[0042] SiO2 is known as a component that forms a network structure within the microstructure of glass and is a major component of glass. The SiO2 content is 65% or more, preferably 67% or more, and more preferably 69% or more. Alternatively, the SiO2 content is 76% or less, preferably 74% or less, and more preferably 72% or less. An SiO2 content of 65% or more is advantageous in terms of glass stability and weather resistance. On the other hand, an SiO2 content of 76% or less is advantageous in terms of meltability and moldability.

[0043] Al2O3 is a component that improves the weather resistance of glass and enhances the ion exchange performance in chemical strengthening. The Al2O3 content is 0.2% or more, preferably 0.4% or more, and more preferably 0.6% or more. Alternatively, the Al2O3 content is 3% or less, preferably 2% or less, and more preferably 1.5% or less. When the Al2O3 content is 0.2% or more, sufficient weather resistance can be obtained even when the glass is used facing the outdoors. On the other hand, when the Al2O3 content is 3% or less, the viscosity during melting of the glass can be kept low, and devitrification does not occur during molding, which is advantageous in terms of melting and molding in soda-lime glass production lines.

[0044] Na2O is a component that lowers the high-temperature viscosity and devitrification temperature of glass, improving its meltability and moldability. It is also a component that forms compressive stress through ion exchange, and has the effect of increasing the depth (DOL) of the compressive stress layer. The Na2O content is 10% or more, preferably 11% or more, and more preferably 12% or more. Alternatively, the Na2O content is 16% or less, preferably 15% or less, and more preferably 14% or less. When the Na2O content is 10% or more, the desired compressive stress can be formed through ion exchange. On the other hand, when the Na2O content is 16% or less, sufficient weather resistance can be obtained.

[0045] K2O is not essential, but it may be included to improve the fusion properties of the glass, enhance its chemical durability, and increase the ion exchange rate. On the other hand, if the amount of K2O is too high, the thermal expansion coefficient of the glass increases, making it more susceptible to thermal cracking and reducing its fire resistance. When K2O is included, it is preferably 2% or less, more preferably 1% or less, and more preferably 0.5% or less. A K2O content of 2% or less makes the glass less prone to thermal cracking and suitable for fire-resistant glass.

[0046] MgO is a component that stabilizes glass. The MgO content is 2% or more, preferably 3% or more, and more preferably 4% or more. Alternatively, the MgO content is 12% or less, preferably 10% or less, and more preferably 9% or less. When the MgO content is 2% or more, the weather resistance of the glass is good. The meltability at high temperatures is also good. On the other hand, when the MgO content is 12% or less, devitrification is less likely to occur during glass manufacturing.

[0047] CaO is a component that stabilizes glass. To improve water resistance and chemical resistance, the CaO content is 5% or more, preferably 6% or more, and more preferably 7% or more. Alternatively, the CaO content can be 15% or less, preferably 13% or less, and more preferably 11% or less. When the CaO content is 5% or more, the water resistance and chemical resistance of the glass are good. On the other hand, when the CaO content is 15% or less, devitrification is less likely to occur during glass manufacturing, and the desired compressive stress can be obtained by ion exchange.

[0048] In addition to the components mentioned above, the product may also contain clarifying agents such as sulfates, and trace components such as Fe2O3, TiO2, ZrO2, and SnO2 in a total amount of 1% or less.

[0049] The curvature of the glass plate 12A to which chemically strengthened glass is applied, as defined in JIS R3206 (2003), is preferably 0.25% or less, more preferably 0.20% or less, and even more preferably 0.15% or less. When the curvature is 0.25% or less, when used as double-glazed glass, gaps in the sealant are less likely to open in the event of a fire, and flames are less likely to leak out. In addition, distortion of the reflected image as window glass can be prevented. The curvature of the glass plate 12A to which chemically strengthened glass is applied can be reduced by controlling the tilt angle of the glass during the chemical strengthening process to ±1.0 degrees, that is, by maintaining the inclination from the vertical direction to ±1.0 degrees or less, thereby suppressing the deflection of the glass.

[0050] Similarly, the warp of the glass plate 12B on which the low-emissivity film 28 is formed, as defined in JIS R3206 (2003), is preferably 0.25% or less, more preferably 0.20% or less, and even more preferably 0.15% or less. When the warp is 0.25% or less, when used as double-glazed glass, gaps in the sealant are less likely to open in the event of a fire, and flames are less likely to leak out. In addition, distortion of the reflected image as window glass can be prevented.

[0051] Figure 2 is a diagram illustrating the measurement locations for the warp of the glass plate. As shown in Figure 2, the warp at positions along the edges connecting the vertices of the glass plate (long sides A and B, short sides C and D, diagonals E and F) was measured according to the method specified in JIS R3206 (2003). By dividing the measured warp (unit: mm) by the length of the measured side (mm), the warp (= The amount of warping (calculation / length of each side) (unit: %) was calculated. Table 1 shows the results of the warping measurement. Variety Regarding the chemical strengthening glass, CT3 is 3mm thick and CT5 is 5mm thick. FR3.3 is 3.3mm thick heat-resistant tempered glass, FR3 is 3mm thick heat-resistant tempered glass, and FR5 is 5mm thick heat-resistant tempered glass. Chemical strengthening glass is manufactured by controlling the tilt angle of the glass during the chemical strengthening process to ±1.0 degrees, that is, maintaining the inclination from the vertical direction to ±1.0 degrees or less, in order to suppress glass deflection. Unlike chemical strengthening glass, heat-resistant tempered glass is manufactured by heating it to 650-700°C, close to the softening temperature of the glass, and then rapidly cooling it by uniformly blowing air on both sides of the glass. The size of the chemical strengthening glass used for measurement was 2000mm x 900mm.

[0052] As shown in Table 1, CT3 and CT5 met the requirement of 0.15% or less, FR3.3 and FR3 had edges that did not meet the requirement of 0.25% or less, and FR5 had edges that did not meet the requirement of 0.15% or less. This demonstrates that CT3 and CT5 can reduce warping.

[0053] [Table 1]

[0054] Next, we will explain the relationship between the curvature of the glass plate and the reflected image. The reflected images of CT3, CT5, FR3, and FR5 mentioned above were evaluated using the grid board method. Figure 3 shows the grid board used in the grid evaluation method. Figure 4 shows an example of evaluation using the grid board method. As shown in Figure 3, a grid board is prepared in the shape of a grid, with equally spaced parallel lines arranged perpendicularly. This grid board is placed on the extension line 10 m away from the glass plate to be evaluated, and the glass plate is observed from 0.5 m in front of the grid board. As a result, as shown in Figure 4, multiple frames enclosed by the grid of the grid board are visible as reflected images on the glass plate. From the multiple frames of the reflected image, the frame with the smallest area enclosed by the circle indicated by arrow A and the frame with the largest area enclosed by the circle indicated by arrow B were extracted, and the horizontal (vertical) stretching frame ratio was calculated from the following equation (1). Table 2 shows the varieties and the values ​​for the expansion / contraction ratio, with the longer side of Figure 4 being the horizontal and the shorter side the vertical (glass size: 2,000mm x 900mm).

[0055]

number

[0056] The smaller the value of the compression ratio shown in equation (1), the better the reflected image.

[0057] [Table 2]

[0058] As shown in Table 2, the frame rate values ​​for CT3 and CT5 are smaller than those for FR3 and FR5. From Tables 1 and 2, it can be seen that by using chemically strengthened glass for glass plate 12A, the warping of the glass plate can be reduced, and as a result, a good reflective image with less distortion can be obtained.

[0059] In the double-glazed glass 10, the glass plate 12B on which the low-emissivity film 28 is formed also exhibits little warping, similar to the chemically strengthened glass plate 12A. Therefore, it can be understood that a good reflective image with minimal distortion can be obtained.

[0060] In double-glazed glass 10, using glass plates 12A and 12B with minimal warping allows for better results in fire resistance tests. When manufacturing double-glazed glass 10, the bending stress applied around the edges of glass plates 12A and 12B can be reduced. Therefore, glass plates 12A and 12B are less likely to deform during fire resistance tests, preventing gaps in the sealant of the double-glazed glass 10 from opening and flame leakage, thus maintaining fire resistance performance and obtaining good fire resistance test results.

[0061] Next, we will explain edge strength. In the fire resistance test of double-glazed glass 10, when a glass plate is heated, thermal expansion occurs in the center of the plate, applying tensile stress to the edges. When this tensile stress exceeds the strength of the edge surface (edge ​​strength) of the glass plate, cracks begin to form starting from minute cracks or scratches from cutting on the edge surface of the glass plate, and these cracks propagate into the glass plate, leading to fracture.

[0062] Due to this fracture mechanism, edge strength is crucial for improving the fire resistance of glass plates. Therefore, as shown in the examples, we investigated the range of edge strength that stabilizes fire resistance.

[0063] In the examples, based on the test method specified in JIS R3223 (2017), the test fixture shown in Figure 5 was used to determine the edge strength of chemically strengthened glass, specifically the stress at which the logarithmic probability of fracture occurs, the minimum value of the edge strength fracture stress, and the average value of the edge strength fracture stress. Here, the stress at which the logarithmic probability of fracture occurs means that when this stress is applied to the glass, there is a possibility that 1 in 1000 pieces will break. The number of samples (N) for evaluating edge strength is preferably 10 or more, and more preferably 20 or more.

[0064] As shown in Figure 5, the glass edge of the test specimen to be evaluated was placed in the test fixture with the support rod side facing downwards. A test specimen with a plate thickness t (mm), a height H of 100 (mm), and a width W of 1000 (mm) was supported by a support span l1 of 900 (mm), with a load span l2 of 300 (mm) and a load point velocity of 1 mm / min, and the edge strength was measured. The edge strength was evaluated by bending deformation tests under these conditions. The fracture load F was substituted into equation (2) to obtain the fracture strength σ fe The 0.1% fracture probability strength of the edge was determined by calculating and statistical processing using a log-normal distribution. In this edge strength evaluation test, the maximum load at which the glass fractured due to bending deformation was defined as the fracture load F. Only data where the fracture initiation point was within the load span and at the edge of the glass plate were statistically processed.

[0065]

number

[0066] Furthermore, the breaking strength σ fe The minimum and average fracture stress values ​​of the edge strength were determined. The edge strength of chemically strengthened glass is preferably 260 MPa or higher, more preferably 280 MPa or higher, and even more preferably 300 MPa or higher, at a stress corresponding to a logarithmic 0.1% fracture probability. The minimum fracture stress value of the edge strength of chemically strengthened glass is preferably 300 MPa or higher, more preferably 330 MPa or higher, and even more preferably 350 MPa or higher. The average fracture stress value of the edge strength of chemically strengthened glass is preferably 360 MPa or higher, more preferably 370 MPa or higher, and even more preferably 380 MPa or higher.

[0067] For the evaluation of edge strength, a 2000mm x 900mm piece of chemically strengthened glass was chamfered, then chemically strengthened. Four glass plates were cut from the chemically strengthened glass to serve as test specimens. Figure 6 shows the process of cutting four glass plates from the chemically strengthened glass. As shown in Figure 6, four glass plates G1, G2, G3, and G4 (1000mm x 100mm) are cut from one glass plate G (2000mm x 900mm), including the periphery of the glass plate.

[0068] The magnitude of edge strength (fracture stress) is affected by the size of the test specimen. The fracture strength of two test specimens is σ fe1 and σ fe2 Let S be the effective surface area of ​​the edge. e1 and S e2 Given that the shape parameter is m, it is known that the following relationship (3) is satisfied. The shape parameter m can be obtained from a Weibull plot in accordance with JIS R1625 (2010).

[0069]

number

[0070] In the case of the glass plate in this embodiment, if the thickness of the glass plate is constant, the effective surface area is the ratio of the effective length. When a large glass plate and a small glass plate have the same thickness, it can be calculated as follows.

[0071] The breaking strength of a large glass plate is σ fe2 If the size of the glass plate is 1000mm(W)×100mm(H) and the effective evaluation length (load span) is 300mm(l2), and the size of the small glass plate is 70mm(W)×20mm(H) and the effective evaluation length (load span) is 20mm(l2), then the fracture strength of the small glass plate is σ fe1 When estimating (MPa), it can be calculated using equation (4) based on equation (3).

[0072]

number

[0073] Regarding the latent scratch depth of chemically strengthened glass, the latent scratch depth of the edge face of the chemically strengthened glass after chamfering, which can achieve stable edge strength and fire resistance, is preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 15 μm or less. The shape of the chamfer applied to the edge face of the chemically strengthened glass is not particularly limited, and can be C-chamfer, R-chamfer, etc. Here, latent scratches refer to microscopic scratches that occur in the glass during processing steps such as shaping the edge face, chamfering, or grinding. These latent scratches can be observed under a microscope because the tips of the scratches open up when etching is performed.

[0074] The ratio of the depth of latent defects to the depth of the compressive stress layer (DOL) of chemically strengthened glass is preferably 95% or less, more preferably 70% or less, and even more preferably 50% or less. By setting the ratio of the depth of latent defects to the depth of the compressive stress layer (DOL) within the above range, fire resistance can be improved.

[0075] Next, we will explain how to measure the depth of a latent wound.

[0076] First, the edges of the chemically strengthened glass are polished to a predetermined degree. Care is taken during this process to avoid creating new latent flaws that may affect the evaluation. Afterward, the glass is etched, cleaned, and dried, then observed under an optical microscope. For example, a 20x objective lens is used, and the observation field is 635 μm × 480 μm. If five or more latent flaws are found during this observation, the polishing amount is adjusted, and the same procedure is performed on a new sample. If fewer than five latent flaws are found, the remaining flaw depth is observed using a laser microscope, and the final flaw depth after polishing is measured. The sum of the final flaw depth and the amount of polishing is considered the original flaw depth of the chemically strengthened glass.

[0077] "Etching" is carried out at room temperature (25 °C) by immersing the entire chemically strengthened glass in an etching solution. As the etching solution, 13 mL of 46 mass% hydrofluoric acid (HF) and 12 g of citric acid are mixed, and a predetermined amount of pure water is mixed to prepare a 3% HF solution. The etching solution is used to penetrate the latent damage formed on the surface and inside of the chemically strengthened glass and to expand and clarify the latent damage.

[0078] The "etching amount" is controlled by the immersion time. Specifically, after calculating the etching rate by performing etching for a predetermined time using glass of the same composition in advance, the etching is carried out by adjusting the immersion time so as to obtain the desired etching amount. Note that depending on the type of glass, the hydrofluoric acid concentration may be changed to adjust the etching rate.

[0079] The size of the latent damage depth is affected by the size of the observation field. Here, the relationship between the latent damage depth and the observation field is the fracture strength σ in the relational expression of Equation (3) fe and the effective surface area S of the edge e and can be estimated from the relationship. The fracture strength σ of the glass fe (σ c ) is known to be inversely proportional to the square root of the depth c of the flaw as shown in Equation (5). Here, K IC is the fracture toughness value of the glass, and Y is a coefficient determined by the shape of the flaw. For the condition that the latent damage depth is 20 μm or less when observed in an observation field of 635 μm × 480 μm, when the observation field changes, the appropriate upper limit value of the latent damage depth can be obtained from Equations (3) and (5) with the values of K IC and Y kept constant.

[0080]

Equation

[0081] [Examples] [Tests] In the test, a plurality of multilayer glasses (test specimens) were prepared and a fire resistance test was carried out.

[0082] <Test Specimen> Test specimens 1 to 7, each consisting of two glass plates, a spacer separating the two glass plates, and a sealing material to seal the two glass plates and the spacer. Each of the two glass plates had a size of 900 mm in width and 2000 mm in height. At least one of the two glass plates was made of chemically strengthened glass, and the edges of the chemically strengthened glass were chamfered before the chemical strengthening treatment. Soda-lime glass with the following composition was used for both the chemically strengthened glass and the other glass.

[0083] Soda-lime glass composition (mol%): SiO2 71.1%, Al2O3 1.1%, Na2O 12.5%, K2O 0.3%, MgO 6.4%, CaO 8.5% In the double-glazed glass of Test Specimen 1, the chemically strengthened glass had a thickness of 5 mm, a surface compressive stress CS of 460 MPa, and a compressive stress layer depth DOL of 30 μm. The glass with a low emissivity coating was a 5 mm thick soda-lime glass with a low emissivity coating of 0.03 or less. The sample size for evaluating the edge strength of Test Specimen 1 was 40, and the sample size for the fire resistance test was 6.

[0084] In the double-glazed glass of test specimen 2, the chemically strengthened glass had a thickness of 5 mm, a surface compressive stress CS of 437 MPa, and a compressive stress layer depth DOL of 27 μm. The glass with a low emissivity coating was a 5 mm thick soda-lime glass with a low emissivity coating of 0.03 or less. The number of samples (N) for the edge strength evaluation of test specimen 2 was 19, and the number of samples (N) for the fire resistance test was 6.

[0085] In the double-glazed glass of test specimen 3, the chemically strengthened glass had a thickness of 3 mm, a surface compressive stress CS of 368 MPa, and a compressive stress layer depth DOL of 40 μm. The glass with a low emissivity coating was a 3 mm thick soda-lime glass with a low emissivity coating of 0.03 or less. The sample size for evaluating the edge strength of test specimen 3 was 20, and the sample size for the fire resistance test was 5.

[0086] In the double-glazed glass of test specimen 4, the chemically strengthened glass had a thickness of 3-4 mm, a surface compressive stress CS of 300 MPa, and a compressive stress layer depth DOL of 33 μm. The glass with a low emissivity coating was a 5 mm thick soda-lime glass with a low emissivity coating of 0.03 or less. The number of specimens (N) for the edge strength evaluation of test specimen 4 was 17, and the number of specimens for the fire resistance test was 4.

[0087] Test specimen 5 was a single pane of glass. The chemically strengthened glass used had a thickness of 3 mm, a surface compressive stress (CS) of 519 MPa, and a compressive stress layer depth (DOL) of 15 μm. The N count for evaluating the edge strength of test specimen 5 was 10 specimens. Note that test specimen 5 was not subjected to fire resistance testing because it was expected that it would not exhibit fire resistance performance.

[0088] In the double-glazed glass of test specimen 6, the chemically strengthened glass had a plate thickness of 3 mm, a surface compressive stress CS of 437 MPa, and a compressive stress layer depth DOL of 27 μm. The glass with a low emissivity coating was soda-lime glass with a plate thickness of 5 mm or 3 mm and a low emissivity coating with a normal emissivity of 0.03 or less. The number of specimens (N) for the edge strength evaluation of test specimen 6 was 11, and the number of specimens (N) for the fire resistance test was 4.

[0089] In the double-glazed glass of test specimen 7, the chemically strengthened glass had a thickness of 3 mm, a surface compressive stress CS of 437 MPa, and a compressive stress layer depth DOL of 27 μm. The glass with a low emissivity coating was a 5 mm thick soda-lime glass with a low emissivity coating of 0.03 or less. The number of specimens (N) for the edge strength evaluation of test specimen 7 was 12, and the number of specimens (N) for the fire resistance test was 6.

[0090] The warpage of the chemically strengthened glass specimens 1-7 was equivalent to that of CT5 and CT3, as shown in Table 1. The warpage of the glass with low-emissivity coating was equivalent to or less than that of CT5 and CT3.

[0091] <Fire Protection Test> Fire safety tests were conducted on test specimens 1 through 7 in accordance with the test procedures of JIS R3223 (2017), and the pass rate for each test specimen was determined.

[0092] Test conditions: The furnace was heated so that the temperature progression measured by the in-furnace thermocouple would be expressed by the following formula.

[0093] T=345log 10 (8t+1)+20 In the above equation, T is the average furnace temperature (°C), and t is the elapsed time of the test (minutes). The test duration was 20 minutes.

[0094] Furthermore, the overlap of the trim strip during the mounting of each test specimen was 10 mm.

[0095] In the fire resistance test, the chemically strengthened glass of the double-glazed glass used in the test specimen was placed on the heated side, and the glass with a low-emissivity coating facing the chemically strengthened glass was placed on the unheated side. The reason for this is explained below.

[0096] When a double-glazed window with a low-emissivity coating is placed on the heated side and chemically strengthened glass on the unheated side, the chemically strengthened glass, which has fire-resistant properties, is on the unheated side. Therefore, even if the low-emissivity coating glass collapses, the chemically strengthened glass on the unheated side often withstands the impact and passes the test. On the other hand, when a double-glazed window is arranged with the low-emissivity coating glass on the unheated side and the chemically strengthened glass on the heated side, the low-emissivity coating reflects heat to the inside of the furnace, causing the chemically strengthened glass to heat up faster than in the aforementioned case. This can lead to greater thermal stress in the chemically strengthened glass, causing it to break, or the sealing material of the double-glazed window to heat up faster, losing its adhesive strength and causing the chemically strengthened glass to collapse. Since the low-emissivity coating glass does not have the same fire resistance as the chemically strengthened glass, flames are more likely to penetrate it. In other words, the latter arrangement pattern is more likely to fail the test due to its configuration.

[0097] In the examples, it can be seen that by conducting fire resistance tests under the latter, more stringent arrangement pattern, the test specimens that pass the tests possess high fire resistance performance.

[0098] Passing criteria: A product was deemed to have passed if the following conditions (1) to (3) were met within 20 minutes from the start of heating; it was deemed to have failed if these conditions were not met. (1) There is no continuous emission of flames on the non-heated side for more than 10 seconds. (2) There is no flame that continues for more than 10 seconds on the non-heated side. (3) No damage or gaps such as breakage or cracks through which flames can pass.

[0099] A pass rate of 70% or higher was marked with ○, a pass rate between 30% and 70% was marked with △, and a pass rate below 30% was marked with ×.

[0100] The fire resistance test will basically follow the test procedures of JIS R 3223, but the glass size can be 900mm wide x 2000mm high or 1200mm wide x 2400mm high. In addition, the overlap of the glazing bead can be 10mm to 13mm in the case of double-glazed glass.

[0101] <Edge Strength> Using the test fixture shown in Figure 5, 1000 mm × 100 mm test pieces were prepared for the chemically strengthened glass used in test specimens 1 to 7, as shown in Figure 6. The edge strength was determined by calculating the stress at which the logarithmic 0.1% fracture probability occurred, the minimum fracture stress, and the average fracture stress.

[0102] <Evaluation Results> Table 3 shows the composition of test specimens 1 to 7, their pass rates and evaluations for fire resistance testing, and the values ​​of each edge strength.

[0103] [Table 3]

[0104] As shown in Table 3, for test specimen 4, the surface compressive stress CS of the chemically strengthened glass was 300 MPa, which does not meet the requirement of a surface compressive stress CS of 340 MPa or more, so the pass rate was 0% and the evaluation was ×. Also, for test specimen 5, the depth DOL of the compressive stress layer was 15 μm, which does not meet the requirement of a compressive stress layer depth DOL of 20 μm or more and 50 μm or less, so it will not pass the fire resistance test and the evaluation was ×. Test specimen 5 has a compressive stress layer depth DOL of less than 20 μm for the chemically strengthened glass, and the depth DOL of the compressive stress layer is insufficient for the latent damage depth, so it is assumed that it will not pass the fire resistance test. Comparing test specimens 5 to 7, the edge strength of test specimen 5 is lower than that of test specimens 6 to 7, so it is assumed that test specimen 5 will not pass the fire resistance test.

[0105] Test specimens 1-3 and 6 and 7 received a rating of △ or higher because their surface compressive stress CS was 340 MPa or higher, and their compressive stress layer depth DOL was between 20 μm and 50 μm. Regarding the edge strength of test specimens 1, 3, and 6, which received a rating of ○, the stress at which the logarithmic 0.1% probability of failure occurred was 260 MPa or higher, the minimum fracture stress was 300 MPa or higher, and the average fracture stress was 360 MPa or higher. It can be understood that the pass rate is very high when the edge strength meets this range.

[0106] Furthermore, comparing test specimen 2 and test specimen 7, it can be seen that test specimen 7, whose edge strength is closer to the range mentioned above, has a higher pass rate than test specimen 2.

[0107] Furthermore, for specimens 3, 4, and 5 out of specimens 1 to 7, the relationship between the compressive stress layer depth DOL and the latent defect depth c was examined. Table 4 shows the compressive stress layer depth DOL, latent defect depth c, c / DOL, edge strength, and fire resistance test evaluation for specimens 3, 4, and 5.

[0108] [Table 4]

[0109] As shown in Table 4, in specimens 4 and 5, which received a failing grade in the fire resistance test, the ratio of the latent defect depth c to the depth DOL of the compressive stress layer exceeded 100%. In specimen 3, which received a passing grade in the fire resistance test, the ratio of the latent defect depth c to the depth DOL of the compressive stress layer was 36.9%. A smaller ratio of the latent defect depth c to the depth DOL of the compressive stress layer results in a higher evaluation. Therefore, it can be inferred that the ratio of the latent defect depth to the depth DOL of the compressive stress layer is preferably 95% or less, more preferably 70% or less, and even more preferably 50% or less. [Explanation of Symbols]

[0110] 10...Double-glazed glass, 12A, 12B...Glass plate, 14...Air gap, 16...Spacer, 18A, 18B...Primary sealant, 20...Secondary sealant, 22...Ventilation hole, 24...Hollow section, 26...Desiccant, 28...Low-emissivity film

Claims

1. A double-glazed glass panel is constructed by separating multiple glass plates with spacers in between, and sealing the edges with a sealing material. At least one of the aforementioned multiple glass plates is a low-emissivity glass plate with a low-emissivity film formed on it, having an emissivity of 0.12 or less. Of the plurality of glass plates other than the glass with the low-emission film, at least one is chemically strengthened glass. The surface compressive stress CS of the chemically strengthened glass is 340 MPa or more. The depth DOL of the compressive stress layer of the chemically strengthened glass is 20 μm or more and 50 μm or less. The thickness of the chemically strengthened glass is 2 mm or more and 10 mm or less. The aforementioned multiple glass plates are soda-lime glass. The aforementioned chemically strengthened glass has a curvature of 0.25% or less as defined in JIS R3206 (2003). The aforementioned low-emissivity coated glass is a double-glazed glass having a curvature of 0.25% or less as defined in JIS R3206 (2003).

2. The chemically strengthened glass has a curvature of 0.20% or less as defined in JIS R3206 (2003), The double-glazed glass according to claim 1, wherein the glass with the low-emissivity film has a curvature of 0.20% or less as defined in JIS R3206 (2003).

3. The double-glazed glass according to claim 1 or 2, wherein the edge strength of the chemically strengthened glass is 260 MPa or more at a stress with a logarithmic probability of fracture of 0.1%.

4. The double-glazed glass according to claim 1 or 2, wherein the minimum fracture stress of the edge strength of the chemically strengthened glass is 300 MPa or more.

5. The double-glazed glass according to claim 1 or 2, wherein the average value of the fracture stress of the edge strength of the chemically strengthened glass is 360 MPa or more.

6. The double-glazed glass according to claim 1 or 2, wherein the depth of latent scratches on the end face of the chemically strengthened glass is 20 μm or less.

7. The double-glazed glass according to claim 1 or 2, wherein the chemically strengthened glass has a ratio of 95% or less of the depth of the latent defect to the depth DOL of the compressive stress layer.

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