Glass, crystallized glass, and chemically strengthened glass

Abstract

To provide glass that achieves excellent strength through chemical strengthening and also possesses excellent radio wave transparency. [Solution] The present invention relates to glass having a specific composition range, wherein the value of Y calculated based on the following formula using the content of each component [MgO], [CaO], [SrO], [BaO], [Li2O], [Na2O], and [K2O] in molar percentages on an oxide basis, is 19.5 or less. Y=1.2×([MgO]+[CaO]+[SrO]+[BaO])+1.6×([Li2O]+[Na2O]+[K2O])

Description

[Technical Field]

[0001] This invention relates to glass, crystallized glass, and chemically strengthened glass. [Background technology]

[0002] For cover glass and other components of mobile devices, chemically strengthened glass is widely used because it is required to be strong enough to withstand drops without easily breaking. Chemically strengthened glass is glass that has been strengthened by ion exchange between alkali ions contained in the glass and alkali ions with larger ionic radii contained in the molten salt, such as by immersing the glass in a molten salt such as sodium nitrate, thereby forming a compressive stress layer on the surface of the glass. For example, Patent Document 1 discloses aluminosilicate glass having a specific composition that can obtain high surface compressive stress through chemical strengthening. Patent Document 2 also discloses a glass article containing SiO2, Al2O3, B2O3, Li2O, and SnO2, and having fusion lines, and states that such a glass article can be strengthened by an ion exchange process.

[0003] On the other hand, in communication equipment such as mobile phones, smartphones, personal digital assistants (PDAs), and Wi-Fi devices, as well as electronic devices such as surface acoustic wave (SAW) devices, radar components, and antenna components, the frequency of signals is being increased to achieve higher communication capacities and faster communication speeds. In recent years, the spread of 5G (fifth-generation mobile communication system) is expected as a new communication system that uses even higher frequency bands. In the high-frequency band used in 5G, cover glass can interfere with radio wave transmission and reception, so 5G-compatible mobile terminals require cover glass with excellent radio wave transparency.

[0004] Several alkali-free glasses have been developed to date to produce glass with high radio wave transparency in high-frequency bands such as those used in 5G, i.e., glass with low relative permittivity and dielectric loss tangent (for example, Patent Document 3). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-520082 [Patent Document 2] Japanese Patent Application Publication No. 2019-532906 [Patent Document 3] International Publication No. 2019 / 181707 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] However, an alkali-free glass that contains almost no alkali ions is difficult to be chemically strengthened, and it is difficult to achieve both radio wave permeability and strength. Further, in the conventional chemically strengthened glasses as described in Patent Documents 1 and 2, the relative permittivity and dielectric loss tangent in the high-frequency region have not been particularly focused on. Even if the strength was sufficient, the radio wave permeability was not sufficient. Therefore, an object of the present invention is to provide a glass that can obtain excellent strength by chemical strengthening and has excellent radio wave permeability. Another object of the present invention is to provide a chemically strengthened glass that has excellent strength and excellent radio wave permeability. [Means for Solving the Problems]

[0007] As a result of investigations, the inventors of the present invention have found that a glass having high strength can be obtained by chemical strengthening by adjusting the glass composition, and the radio wave permeability is also good, and thus the present invention has been achieved.

[0008] That is, the present invention is represented by a molar percentage based on oxides, SiO2 is 50.0 to 75.0%, Al2O3 is 7.5 to 25.0%, B2O3 is 0 to the 25.0%, Li2O is 6.5 to 20.0%, Na2O is 1.5 to 10.0%, K2O is 0 to 4.0%, MgO is 1.0 to 20.0%, One or more substances selected from MgO, CaO, SrO, and BaO, totaling 1.0-20.0%. It contains 0-5.0% TiO2, This relates to glass in which the value of Y, calculated based on the following formula using the molar percentage content of each component [MgO], [CaO], [SrO], [BaO], [Li2O], [Na2O], and [K2O] on an oxide basis, is 19.5 or less. Y=1.2×([MgO]+[CaO]+[SrO]+[BaO])+1.6×([Li2O]+[Na2O]+[K2O])

[0009] In the glass of the present invention, it is preferable that the value of X calculated based on the following formula, using the content of each component Al2O3, MgO, Li2O, Na2O, and K2O in molar percentages on an oxide basis [Al2O3], [MgO], [Li2O], [Na2O], and [K2O], is 30.0 or higher. X=3×[Al2O3]+[MgO]+[Li2O]-2×([Na2O]+[K2O])

[0010] This invention expresses the mole percentage based on oxides, SiO2 at 55.0-75.0%, Al2O3 at 9.1-25.0% B2O3 at 0-14.0% Li2O at 7.5-12.5% Na2O at 3.6-10.0%, K2O at 0-2.0%, One or more of the following are selected from MgO, CaO, SrO, and BaO, totaling 0-13.0%. It contains 0-8.0% ZnO, This relates to glass in which the value of X calculated based on the following formula is 25.0 or greater and the value of Z is 22.0 or less, using the content of each component [Al2O3], [B2O3], [MgO], [Li2O], [Na2O], and [K2O] in molar percentages on an oxide basis. X=3×[Al2O3]+[MgO]+[Li2O]-2×([Na2O]+[K2O]) Z=3×[Al2O3]-3×[B2O3]-2×[Li2O]+4×[Na2O]

[0011] This invention expresses the mole percentage based on oxides, SiO2 at 50.0-75.0%, Al2O3 at 9.0-25.0% B2O3 at 0-20.0% Li2O at 6.5-14.5% Na2O at 2.5-10.0% K2O at 0-4.0%, One or more elements selected from MgO, CaO, SrO, and BaO, totaling 0-20.0%. It contains 0-3.0% TiO2, This relates to glass in which the value of X calculated based on the following formula, using the molar percentage content of each component Al2O3, B2O3, MgO, CaO, SrO, BaO, Li2O, Na2O, and K2O on an oxide basis, is 35.0 or greater, and the sum of the values ​​of Y and Z is 35.0 or less. X=3×[Al2O3]+[MgO]+[Li2O]-2×([Na2O]+[K2O]) Y=1.2×([MgO]+[CaO]+[SrO]+[BaO])+1.6×([Li2O]+[Na2O]+[K2O]) Z=3×[Al2O3]-3×[B2O3]-2×[Li2O]+4×[Na2O]

[0012] The glass of the present invention preferably has a plate thickness (t) of 100 μm or more and 2000 μm or less.

[0013] In this invention, the base composition is expressed as a mole percentage based on oxides. SiO2 at 50.0-75.0%, B2O3 at 0-25.0% Al2O3 at 7.5-25.0% Li2O at 6.5-20.0% Na2O at 1.5-10.0%, K2O at 0-4.0%, MgO at 1.0-20.0% One or more substances selected from MgO, CaO, SrO, and BaO, totaling 1.0-20.0%. It contains 0-5.0% TiO2, This relates to chemically strengthened glass in which the value of Y, calculated based on the following formula using the content of each component [MgO], [CaO], [SrO], [BaO], [Li2O], [Na2O], and [K2O] in molar percentages on an oxide basis, is 19.5 or less. Y=1.2×([MgO]+[CaO]+[SrO]+[BaO])+1.6×([Li2O]+[Na2O]+[K2O])

[0014] The chemically strengthened glass of the present invention preferably has a surface compressive stress value CS0 of 300 MPa or higher. The chemically strengthened glass of the present invention has a compressive stress value CS at a depth of 50 μm from the glass surface. 50 It is preferable that the pressure is 75 MPa or higher and the plate thickness (t) is 300 μm or higher. The chemically strengthened glass of the present invention preferably has a compressive stress layer depth (DOL) of 80 μm or more and a plate thickness (t) of 350 μm or more.

[0015] The present invention relates to crystallized glass having the glass composition of the glass of the present invention as described above. [Effects of the Invention]

[0016] The glass of the present invention, due to its glass composition being within a specific range, achieves high strength through chemical strengthening and exhibits excellent radio wave transparency. Furthermore, the chemically strengthened glass of the present invention exhibits excellent strength and radio wave transparency. [Brief explanation of the drawing]

[0017] [Figure 1]Figure 1 shows the relationship between parameter X and the surface compressive stress value CS0(Na) when the glass is chemically strengthened in an example of this glass. [Figure 2] Figure 2 shows the relationship between parameter Y and the relative permittivity at 10 GHz in an embodiment of this glass. [Figure 3] Figure 3 shows the relationship between the parameter Z and the dielectric loss tangent tanδ at 10 GHz in an embodiment of this glass. [Modes for carrying out the invention]

[0018] In this specification, the symbol "~" indicating a numerical range includes the values ​​before and after it as the lower and upper limits. Unless otherwise specified, "~" will be used in the same sense hereafter in this specification.

[0019] In this specification, "chemically strengthened glass" refers to glass that has undergone chemical strengthening treatment, and "glass for chemical strengthening" refers to glass that has not undergone chemical strengthening treatment. In this specification, "matrix composition of chemically strengthened glass" refers to the glass composition of chemically strengthened glass. In chemically strengthened glass, except in cases of extreme ion exchange treatment, the glass composition at a depth of half the plate thickness t is the matrix composition of the chemically strengthened glass.

[0020] In this specification, glass composition is expressed in molar percentages based on oxides unless otherwise specified, and mole percent is simply denoted as "%". Furthermore, in this specification, "substantially absent" means that the level is below the level of impurities contained in the raw materials, etc., that is, it is not intentionally included. Specifically, "substantially absent" means, for example, that the content is less than 0.1 mol%.

[0021] In this specification, "stress profile" refers to the compressive stress value expressed with respect to the depth from the glass surface. "Compressive stress layer depth (DOL)" is the depth at which the compressive stress value (CS) becomes zero. "Internal tensile stress value (CT)" refers to the tensile stress value at a depth of half the glass plate thickness t.

[0022] The stress profiles described herein can be measured using a scattered light photoelastic stress meter (for example, the SLP-1000 manufactured by Orihara Seisakusho Co., Ltd.). Scattered light photoelastic stress meters may experience reduced measurement accuracy near the sample surface due to surface scattering. However, if compressive stress is generated solely by ion exchange between lithium ions in the glass and external sodium ions, for example, the compressive stress value expressed as a function of depth follows a complementary error function, allowing the surface stress value to be determined by measuring the internal stress value. If the compressive stress value expressed as a function of depth does not follow a complementary error function, the surface portion should be measured by another method, such as using a surface stress meter.

[0023] <Glass> In the embodiment of the present invention (hereinafter sometimes referred to as "this glass"), lithium aluminosilicate glass is preferred. Since lithium aluminosilicate glass contains lithium ions, which are the alkali ions with the smallest ionic radius, it is easy to obtain chemically strengthened glass with a desirable stress profile and excellent strength by chemical strengthening treatment using ion exchange with various molten salts.

[0024] Specifically, this glass is, SiO2 at 50.0-75.0%, Al2O3 at 7.5-25.0% Li2O 6.5-20.0% It is preferable to include it.

[0025] Furthermore, this glass also... B2O3 at 0-25.0% Na2O at 1.5-10.0%, K2O at 0-4.0%, It is preferable that the mixture contains a total of 0-20.0% of one or more elements selected from MgO, CaO, SrO, and BaO.

[0026] The glass preferably has a parameter X value of 25.0 or higher, calculated based on the following formula using the content of each component Al2O3, MgO, Li2O, Na2O, and K2O in molar percentages on an oxide basis [Al2O3], [MgO], [Li2O], [Na2O], and [K2O]. A parameter X value of 30.0 or higher is more preferable, 35.0 or higher is even more preferable, 37.5 or higher is even more preferable, 40.0 or higher is particularly preferable, 42.0 or higher is even more preferable, and 45.0 or higher is most preferable. X=3×[Al2O3]+[MgO]+[Li2O]-2×([Na2O]+[K2O])

[0027] Figure 1 shows the relationship between the value of parameter X and the surface compressive stress value CS0(Na) when the glass is chemically strengthened in an example of this glass. Here, the surface compressive stress value CS0(Na) refers to the surface compressive stress value when the glass is chemically strengthened by immersing it in a 100% sodium nitrate salt at 450°C for 1 hour. From Figure 1, it can be seen that the larger the value of parameter X, the greater the tendency for CS0(Na) to be. Specifically, a value of parameter X of 25.0 or higher makes it easier to obtain chemically strengthened glass with excellent strength through chemical strengthening. From the viewpoint of glass strengthening time, the value of parameter X is preferably 80.0 or less, more preferably 55.0 or less, even more preferably 50.0 or less, even more preferably 49.0 or less, particularly preferably 48.0 or less, even more preferably 47.0 or less, and most preferably 46.0 or less.

[0028] The glass preferably has a parameter Y value of 19.5 or less, calculated based on the following formula using the molar percentage content of each component [MgO], [CaO], [SrO], [BaO], [Li2O], [Na2O], and [K2O] on an oxide basis. The parameter Y value is more preferably 19.0 or less, even more preferably 18.5 or less, even more preferably 18.25 or less, particularly preferably 18.0 or less, even more preferably 17.5 or less, and most preferably 17.0 or less. Furthermore, if a large amount of B2O3 is present, it is preferable to reduce the amount of components that increase the Y value from the viewpoint of suppressing phase separation of the glass. Specifically, if the amount of B2O3 exceeds 5.0%, the Y value is preferably 18.0 or less, more preferably 17.75 or less, even more preferably 17.5 or less, even more preferably 17.25 or less, particularly preferably 17.0 or less, even more preferably 16.75 or less, and most preferably 16.5 or less. Y=1.2×([MgO]+[CaO]+[SrO]+[BaO])+1.6×([Li2O]+[Na2O]+[K2O])

[0029] Figure 2 shows the relationship between the value of parameter Y and the relative permittivity at 10 GHz in an embodiment of this glass. From Figure 2, it can be seen that the smaller the value of parameter Y, the lower the relative permittivity at 10 GHz tends to be. Specifically, by setting the value of parameter Y to 19.5 or less, it is easier to obtain glass with a lower relative permittivity and good radio wave transparency. From the viewpoint of making the glass high strength, the value of parameter Y is preferably 10.0 or higher, more preferably 11.0 or higher, even more preferably 12.0 or higher, even more preferably 13.0 or higher, particularly preferably 14.0 or higher, even more preferably 15.0 or higher, and most preferably 15.5 or higher.

[0030] In this glass, the value of parameter Z, calculated based on the following formula using the content of each component Al2O3, B2O3, Li2O, and Na2O in molar percentages on an oxide basis [Al2O3], [B2O3], [Li2O], and [Na2O], is preferably 22.0 or less, more preferably 21.0 or less, even more preferably 20.0 or less, even more preferably 19.0 or less, particularly preferably 18.0 or less, even more preferably 14.0 or less, and most preferably 12.0 or less. Z=3×[Al2O3]-3×[B2O3]-2×[Li2O]+4×[Na2O]

[0031] Figure 3 shows the relationship between the value of parameter Z and the dielectric loss tangent tanδ at 10 GHz in an embodiment of this glass. It can be seen that the smaller the value of parameter Z, the smaller the tanδ at 10 GHz tends to be. Specifically, when the value of parameter Z is 22.0 or less, it is easier to obtain glass with a smaller dielectric loss tangent and good radio wave transparency. From the viewpoint of obtaining high-strength glass during chemical strengthening, the value of parameter Z is preferably -5.0 or higher, more preferably 0.0 or higher, even more preferably 2.0 or higher, even more preferably 4.0 or higher, particularly preferably 6.0 or higher, even more preferably 8.0 or higher, and most preferably 10.0 or higher.

[0032] The sum of the values ​​of parameter Y and parameter Z for this glass is preferably 35.0 or less, more preferably 33.0 or less, even more preferably 32.0 or less, even more preferably 31.0 or less, particularly preferably 30.0 or less, even more preferably 29.0 or less, and most preferably 28.0 or less. Furthermore, if a large amount of B2O3 is present, it is preferable to reduce the amount of components that increase the values ​​of Y and Z from the viewpoint of suppressing phase separation of the glass. Specifically, if the amount of B2O3 exceeds 5.0%, the value of Y+Z is preferably 34.0 or less, more preferably 32.0 or less, even more preferably 30.0 or less, even more preferably 28.0 or less, particularly preferably 27.0 or less, even more preferably 26.0 or less, and most preferably 25.5 or less. When the sum of the Y and Z values ​​is 35.0 or less, it is easier to obtain glass with both low relative permittivity and dielectric loss tangent, resulting in good radio wave transmittance. From the viewpoint of making the glass high-strength, the sum of the Y and Z values ​​is preferably 0.0 or higher, more preferably 10.0 or higher, even more preferably 15.0 or higher, even more preferably 20.0 or higher, particularly preferably 21.0 or higher, even more preferably 23.0 or higher, and most preferably 25.0 or higher.

[0033] The preferred composition of this glass will be further described below.

[0034] SiO2 is a component that makes up the network of glass. Furthermore, SiO2 is a component that increases chemical durability and reduces the occurrence of cracks when the glass surface is scratched. To improve chemical durability, the SiO2 content is preferably 50.0% or more, more preferably 52.0% or more, even more preferably 55.0% or more, even more preferably 56.0% or more, particularly preferably 60.0% or more, even more preferably 62.0% or more, even more preferably 64.0% or more, and most preferably 66.0% or more. On the other hand, to improve melting properties during glass manufacturing, the SiO2 content is preferably 75.0% or less, more preferably 74.0% or less, even more preferably 72.0% or less, even more preferably 71.0% or less, particularly preferably 70.0% or less, even more preferably 69.0% or less, and most preferably 68.0% or less.

[0035] Al2O3 is an effective component in chemical strengthening because it improves ion exchange performance and increases the surface compressive stress after strengthening. The Al2O3 content is preferably 7.5% or more, more preferably 9.0% or more, even more preferably 9.1% or more, even more preferably 9.5% or more, particularly preferably 10.0% or more, even more preferably 11.0% or more, and most preferably 12.0% or more, in order to improve chemical durability and chemical strengthening properties. On the other hand, if the Al2O3 content is too high, crystals may grow more easily during melting. In order to prevent yield reduction due to devitrification defects, the Al2O3 content is preferably 25.0% or less, more preferably 23.0% or less, even more preferably 21.0% or less, even more preferably 20.0% or less, particularly preferably 16.0% or less, even more preferably 15.0% or less, and most preferably 13.5% or less.

[0036] SiO2 and Al2O3 are both components that stabilize the structure of glass, and in order to reduce brittleness, the total content is preferably 57.5% or more, more preferably 65.0% or more, even more preferably 75.0% or more, even more preferably 77.0% or more, and particularly preferably 79.0% or more. Both SiO2 and Al2O3 tend to increase the melting temperature of glass. Therefore, in order to facilitate the melting of glass, the total content of these elements is preferably 95.0% or less, more preferably 90.0% or less, even more preferably 87.0% or less, even more preferably 85.0% or less, and particularly preferably 82.0% or less.

[0037] Li2O is a component that forms surface compressive stress through ion exchange and improves the meltability of glass. By including Li2O in chemically strengthened glass, Li ions on the glass surface are exchanged for Na ions, and then Na ions are exchanged for K ions, resulting in a stress profile with large surface compressive stress and a large compressive stress layer.

[0038] To increase the surface compressive stress during chemical strengthening, the Li2O content is preferably 6.5% or more, more preferably 7.1% or more, even more preferably 7.5% or more, even more preferably 7.6% or more, particularly preferably 8.0% or more, even more preferably 8.1% or more, even more preferably 8.5% or more, and most preferably 9.0% or more. On the other hand, if the Li2O content is too high, the crystal growth rate during glass molding increases, which can lead to a greater problem of reduced yield due to devitrification defects. To suppress devitrification during the glass manufacturing process, the Li2O content is preferably 20.0% or less, more preferably 18.0% or less, even more preferably 16.0% or less, even more preferably 14.5% or less, particularly preferably 14.0% or less, even more particularly preferably 12.5% ​​or less, even more preferably 12.0% or less, and most preferably 11.0% or less. Furthermore, if the alkali ion content is too high, the radio wave transparency tends to decrease, so from the viewpoint of improving radio wave transparency, the Li2O content is preferably 12.0% or less, more preferably 11.0% or less, even more preferably 10.0% or less, and even more preferably 9.5% or less.

[0039] Although neither Na2O nor K2O are essential, they are components that improve the meltability of the glass and reduce the crystal growth rate of the glass, and it is preferable to include them in order to improve the ion exchange performance.

[0040] Na2O is a component that forms a surface compressive stress layer in chemical strengthening treatment using potassium salts, and is also a component that can improve the meltability of glass. To obtain this effect, the Na2O content is preferably 1.5% or more, more preferably 2.5% or more, even more preferably 3.0% or more, even more preferably 3.3% or more, particularly preferably 3.5% or more, even more preferably 3.6% or more, and most preferably 4.0% or more. On the other hand, if the Na2O content is too high, it becomes difficult to increase the compressive stress in the relatively deep parts from the surface by chemical strengthening, so from this viewpoint, the content is preferably 10.0% or less, more preferably 9.0% or less, even more preferably 8.0% or less, even more preferably 7.0% or less, particularly preferably 6.0% or less, even more preferably 5.5% or less, and most preferably 5.0% or less.

[0041] K2O may be included for purposes such as suppressing devitrification during the glass manufacturing process. When K2O is included, the content is preferably 0.1% or more, more preferably 0.15% or more, even more preferably 0.2% or more, even more preferably 0.25% or more, particularly preferably 0.3% or more, and even more preferably 0.4% or more. Furthermore, to further prevent devitrification, the K2O content is preferably 0.45% or more, more preferably 0.6% or more, even more preferably 0.7% or more, even more preferably 0.8% or more, particularly preferably 0.9% or more, and even more preferably 1.0% or more. On the other hand, from the viewpoint of suppressing increased brittleness and preventing a decrease in surface stress due to reverse exchange during strengthening, the K2O content is preferably 4.0% or less, more preferably 3.5% or less, even more preferably 3.0% or less, even more preferably 2.5% or less, particularly preferably 2.0% or less, even more preferably 1.5% or less, even more preferably 1.3% or less, and most preferably 1.1% or less.

[0042] The total content of Na2O and K2O ([Na2O]+[K2O]) is preferably 1.0% or more, more preferably 2.0% or more, even more preferably 3.0% or more, even more preferably 4.0% or more, particularly preferably 5.0% or more, even more preferably 5.5% or more, and most preferably 6.0% or more, in order to increase the meltability of the glass. If ([Na2O]+[K2O]) is too high, a decrease in the surface compressive stress value is likely to occur, so ([Na2O]+[K2O]) is preferably 18.0% or less, more preferably 16.0% or less, even more preferably 15.0% or less, even more preferably 14.0% or less, particularly preferably 12.0% or less, even more preferably 10.0% or less, and most preferably 8.0% or less. Furthermore, the coexistence of Na2O and K2O suppresses the movement of alkaline components, which is preferable from the viewpoint of radio wave transparency.

[0043] MgO, CaO, SrO, and BaO are not essential, but one or more of them may be included from the viewpoint of improving the stability of the glass and enhancing its chemical strengthening properties. When these are included, the total amount of one or more selected from MgO, CaO, SrO, and BaO, [MgO]+[CaO]+[SrO]+[BaO], is preferably 1.0% or more, more preferably 1.5% or more, even more preferably 2.0% or more, even more preferably 2.5% or more, particularly preferably 3.0% or more, even more preferably 3.5% or more, and most preferably 5.0% or more. Furthermore, from the viewpoint of applying sufficient chemical strengthening stress during chemical strengthening and improving radio wave transparency, the total content of these materials is preferably 20.0% or less, more preferably 16.0% or less, even more preferably 15.0% or less, even more preferably 14.0% or less, particularly preferably 13.0% or less, even more particularly preferably 12.0% or less, even more preferably 10.0% or less, and most preferably 8.0% or less.

[0044] MgO may be included to reduce viscosity during dissolution, etc. When MgO is included, the content is preferably 1.0% or more, more preferably 1.5% or more, even more preferably 2.0% or more, even more preferably 2.5% or more, particularly preferably 3.0% or more, even more preferably 3.5% or more, and most preferably 5.0% or more. On the other hand, if the MgO content is too high, it becomes difficult to increase the compressive stress layer during chemical strengthening treatment. The MgO content is preferably 20.0% or less, more preferably 16.0% or less, even more preferably 15.0% or less, even more preferably 14.0% or less, particularly preferably 12.0% or less, even more preferably 10.0% or less, and most preferably 8.0% or less.

[0045] CaO is a component that improves the meltability of glass and may be included. When CaO is included, the content is preferably 0.1% or more, more preferably 0.15% or more, and even more preferably 0.5% or more. On the other hand, if the CaO content is excessive, it becomes difficult to increase the compressive stress value during chemical strengthening treatment. From this viewpoint, the CaO content is preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, and typically 1.0% or less.

[0046] ZnO is not essential, but it is a component that improves the meltability of the glass and may be included. If ZnO is included, the content is preferably 0.2% or more, more preferably 0.5% or more. To improve the weather resistance of the glass, the ZnO content is preferably 8.0% or less, more preferably 5.0% or less, and even more preferably 3.0% or less.

[0047] Since ZnO, SrO, and BaO tend to degrade chemical strengthening properties, the total content of these elements [ZnO] + [SrO] + [BaO] is preferably less than 1.0%, and more preferably 0.5% or less, in order to facilitate chemical strengthening. It is even more preferable that they are substantially absent.

[0048] While ZrO2 is not required to be included, its inclusion is preferable from the viewpoint of increasing the surface compressive stress of the chemically strengthened glass. The ZrO2 content is preferably 0.1% or more, more preferably 0.15% or more, even more preferably 0.2% or more, particularly preferably 0.25% or more, and typically 0.3% or more. On the other hand, if the ZrO2 content is too high, devitrification defects are more likely to occur, making it difficult to increase the compressive stress value during the chemical strengthening treatment. The ZrO2 content is preferably 2.0% or less, more preferably 1.5% or less, even more preferably 1.0% or less, and particularly preferably 0.8% or less.

[0049] While Y2O3 is not essential, its inclusion is preferable to increase the surface compressive stress of the chemically strengthened glass while reducing the crystal growth rate. Furthermore, to increase the fracture toughness, it is preferable to include at least 0.2% in total of one or more of Y2O3, La2O3, and ZrO2. The total content of Y2O3, La2O3, and ZrO2 is preferably 0.5% or more, more preferably 1.0% or more, and even more preferably 1.5% or more. In addition, to lower the liquidus temperature and suppress devitrification, the total content of these elements is preferably 6.0% or less, more preferably 5.0% or less, and even more preferably 4.0% or less.

[0050] In order to lower the devitrification temperature and suppress devitrification, it is preferable that the total amount of Y2O3 and La2O3 is greater than the amount of ZrO2, and more preferably that the amount of Y2O3 is greater than the amount of ZrO2.

[0051] The Y2O3 content is preferably 0.1% or more, more preferably 0.2% or more, even more preferably 0.5% or more, and particularly preferably 1.0% or more. On the other hand, if the Y2O3 content is too high, it becomes difficult to increase the compressive stress layer during chemical strengthening treatment. The Y2O3 content is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, particularly preferably 2.0% or less, and even more particularly preferably 1.5% or less.

[0052] La2O3 is not essential, but can be included for the same reasons as Y2O3. The amount of La2O3 is preferably 0.1% or more, more preferably 0.2% or more, even more preferably 0.5% or more, and particularly preferably 0.8% or more. On the other hand, if there is too much, it becomes difficult to increase the compressive stress layer during chemical strengthening treatment, so it is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, and particularly preferably 1.5% or less.

[0053] TiO2 is not essential, but it is a component that suppresses solarization of glass and may be included. When TiO2 is included, the content is preferably 0.02% or more, more preferably 0.03% or more, even more preferably 0.04% or more, particularly preferably 0.05% or more, and typically 0.06% or more. On the other hand, if the TiO2 content exceeds 5.0%, devitrification is likely to occur, which may degrade the quality of the chemically strengthened glass. The TiO2 content is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, even more preferably 1.0% or less, particularly preferably 0.5% or less, and even more preferably 0.25% or less.

[0054] B2O3 is not essential, but it may be included to reduce the brittleness of the glass, improve crack resistance, and improve radio wave transparency. When B2O3 is included, the content is preferably 2.0% or more, more preferably 3.0% or more, even more preferably 4.0% or more, even more preferably 5.0% or more, particularly preferably 6.0% or more, even more preferably 7.0% or more, and most preferably 8.0% or more. On the other hand, if the B2O3 content is too high, the acid resistance tends to deteriorate, so the B2O3 content is preferably 25.0% or less. The B2O3 content is more preferably 20.0% or less, even more preferably 17.0% or less, even more preferably 14.0% or less, particularly preferably 12.0% or less, even more preferably 10.0% or less, and most preferably 9.0% or less.

[0055] P2O5 is not essential, but it may be included to increase the compressive stress layer during chemical strengthening. When P2O5 is included, the content is preferably 0.5% or more, more preferably 1.0% or more, even more preferably 2.0% or more, even more preferably 2.5% or more, particularly preferably 3.0% or more, even more preferably 3.5% or more, and most preferably 4.0% or more. On the other hand, from the viewpoint of increasing acid resistance, the P2O5 content is preferably 10.0% or less, more preferably 9.0% or less, even more preferably 8.0% or less, even more preferably 7.0% or less, particularly preferably 6.0% or less, and even more preferably 5.0% or less.

[0056] The total content of B2O3 and P2O5 is preferably 0 to 35.0%, more preferably 3.0% or more, more preferably 5.0% or more, even more preferably 7.0% or more, even more preferably 9.0% or more, particularly preferably 11.0% or more, even more preferably 13.0% or more, and most preferably 15.0% or more. The total content of B2O3 and P2O5 is preferably 35.0% or less, more preferably 25.0% or less. Even more preferably 23.0% or less, even more preferably 21.0% or less, particularly preferably 20.0% or less, even more preferably 19.0% or less, and most preferably 18.0% or less.

[0057] Nb2O 5、 Ta2O5, Gd2O3, and CeO2 are components that suppress the solarization of glass and improve meltability, and may be included. When these components are included, their total content is preferably 0.03% or more, more preferably 0.1% or more, even more preferably 0.3% or more, and typically 0.5% or more. On the other hand, if the content of these components is too high, it becomes difficult to increase the compressive stress value during chemical strengthening treatment. From this viewpoint, the total content of these components is preferably 3.0% or less, more preferably 2.0% or less, and particularly preferably 1.0% or less.

[0058] Fe2O3 absorbs heat rays, thus improving the solubility of glass, and its inclusion is preferable when mass-producing glass using large melting furnaces. In this case, the content is preferably 0.002% or more, more preferably 0.005% or more, even more preferably 0.007% or more, and particularly preferably 0.01% or more, based on the weight percentage of oxides. On the other hand, excessive Fe2O3 content causes discoloration, so from the viewpoint of improving the transparency of the glass, its content is preferably 0.3% or less, more preferably 0.04% or less, even more preferably 0.025% or less, and particularly preferably 0.015% or less, based on the weight percentage of oxides.

[0059] Here, we have described all iron oxides in glass as Fe2O3, but in reality, a mixture of oxidized Fe(III) and reduced Fe(II) is usually present. Of these, Fe(III) causes yellow discoloration, Fe(II) causes blue discoloration, and the balance between the two causes green discoloration in the glass.

[0060] Furthermore, coloring components may be added to the extent that they do not hinder the achievement of the desired chemical strengthening properties. Suitable coloring components include, for example, Co3O4, MnO2, NiO, CuO, Cr2O3, V2O5, Bi2O3, SeO2, CeO2, Er2O3, and Nd2O3.

[0061] The content of coloring components is preferably 5.0% or less in total, expressed as a mole percentage based on oxides. If it exceeds 5.0%, the glass may become devitrified. The content of coloring components is preferably 3.0% or less, and more preferably 1.0% or less. If it is desired to increase the transmittance of the glass, it is preferable that these components are substantially absent.

[0062] SO3, chlorides, fluorides, etc., may be appropriately included as clarifying agents during glass melting. It is preferable that As2O3 is not included. If Sb2O3 is included, it is preferable that it be 0.3% or less, more preferably 0.1% or less, and most preferably not included.

[0063] Specific examples of preferred compositions for this glass, though not limited to these, include the following compositional examples 1 to 4.

[0064] (Composition Example 1) SiO2 at 50.0-75.0%, Al2O3 at 7.5-25.0% B2O3 at 0-25.0% Li2O at 6.5-20.0% Na2O at 1.5-10.0%, K2O at 0-4.0%, MgO at 1.0-20.0% One or more substances selected from MgO, CaO, SrO, and BaO, totaling 1.0-20.0%. It contains 0-5.0% TiO2, Glass with a Y value of 19.5 or less.

[0065] Composition Example 1 is preferred because it is easy to obtain glass with high strength through chemical strengthening and good radio wave transparency. Furthermore, since the glass of Composition Example 1 has a low relative permittivity and a low dielectric loss tangent, it can suppress both the absorption and reflection of radio waves and transmits radio waves easily.

[0066] (Composition example 2) SiO2 at 50.0-75.0%, Al2O3 at 7.5-25.0% B2O3 at 0-25.0% Li2O at 6.5-20.0% Na2O at 1.5-10.0%, K2O at 0-4.0%, MgO at 1.0-20.0% One or more substances selected from MgO, CaO, SrO, and BaO, totaling 1.0-20.0%. It contains 0-5.0% TiO2. Glass with an X value of 30.0 or greater and a Y value of 19.5 or less.

[0067] Composition Example 2 is preferred because it is easy to obtain glass with high strength through chemical strengthening and good radio wave transparency. The glass of Composition Example 2 tends to be stronger when the value of X is large.

[0068] (Composition Example 3) SiO2 at 55.0-75.0%, Al2O3 at 9.1-25.0% B2O3 at 0-14.0% Li2O at 7.5-12.5% Na2O at 3.6-10.0%, K2O at 0-2.0%, One or more of the following are selected from MgO, CaO, SrO, and BaO, totaling 0-13.0%. It contains 0-8.0% ZnO, Glass in which the value of X is 25.0 or greater and the value of Z is 22.0 or less.

[0069] Composition Example 3 is preferred because it allows for obtaining high strength through chemical strengthening, and makes it easier to obtain glass with a smaller dielectric loss tangent and good radio wave transparency.

[0070] (Composition Example 4) SiO2 at 50.0-75.0%, Al2O3 at 9.0-25.0% B2O3 at 0-20.0% Li2O at 6.5-14.5% Na2O at 2.5-10.0% K2O at 0-4.0%, One or more elements selected from MgO, CaO, SrO, and BaO, totaling 0-20.0%. It contains 0-3.0% TiO2, Glass where the value of X is 35.0 or greater, and the sum of Y and Z is 35.0 or less.

[0071] Composition example 4 is preferred because it allows for high strength to be obtained through chemical strengthening, and also makes it easier to obtain glass with good radio wave transparency due to its smaller relative permittivity and dielectric loss tangent.

[0072] The relative permittivity of this glass at 20°C and 10GHz is preferably 7.0 or less, more preferably 6.5 or less, and even more preferably 6.0 or less. A low relative permittivity suppresses radio wave loss due to reflection at the glass surface, thus resulting in good radio wave transparency. The lower limit of the relative permittivity is not particularly limited, but is usually 4.0 or higher.

[0073] The dielectric loss tangent (tanδ) of this glass at 20°C and 10GHz is preferably 0.015 or less, more preferably 0.012 or less, and even more preferably 0.01 or less. A small dielectric loss tangent suppresses the loss of radio waves as they pass through the glass, resulting in good radio wave transparency. There is no particular lower limit to the dielectric loss tangent, but it is usually 0.001 or higher.

[0074] Furthermore, it is preferable to bring the relative permittivity and dielectric loss tangent values ​​at 20°C and 10GHz closer to those at higher frequencies, thereby reducing frequency dependence (dielectric dispersion). This makes the frequency characteristics of the dielectric properties less prone to change, and reduces the need for design changes when using different frequencies. The relative permittivity and dielectric loss tangent can be adjusted by the composition of the glass.

[0075] Because the alkali content in this glass is appropriately adjusted in its glass composition, the relative permittivity and dielectric loss tangent at 10 GHz are small. Generally, in the frequency range of 10 GHz to 40 GHz, the frequency dependence of the relative permittivity and dielectric loss tangent of glass is small. Therefore, this glass, which has excellent dielectric properties at 10 GHz, also exhibits excellent radio wave transparency in bands such as 28 GHz and 35 GHz used in 5G.

[0076] Furthermore, the relative permittivity and dielectric loss tangent can be measured using a cavity resonator and a vector network analyzer in accordance with the method specified in JIS R1641 (2007).

[0077] The β-OH value is a value used as an indicator of the water content of glass. It is measured by the absorbance to light with a wavelength of 2.75 to 2.95 μm, and the maximum value β is used.max It is a value obtained by dividing by the glass thickness (mm).

[0078] Set the β-OH value to 0.8 mm -1 By setting it as follows, the radio wave permeability of the glass can be further improved, which is preferable. The β-OH value is 0.6 mm -1 The following is more preferable, and 0.5 mm -1 The following is even more preferable, and 0.4 mm -1 The following is even more preferable. On the other hand, by setting the β-OH value to 0.05 mm -1 or more, it is not necessary to dissolve in an extremely dry atmosphere or extremely reduce the moisture content in the raw materials, and the productivity of the glass and the quality of the foam can be improved, which is preferable. The β-OH value is 0.1 mm -1 The following is more preferable, and 0.2 mm -1 The following is even more preferable. The β-OH value can be adjusted according to the composition of the glass, the heat source during melting, the melting time, and the raw materials.

[0079] In this glass, when chemically strengthened by immersing in a 100% sodium nitrate salt at 450 °C for 1 hour, the surface compressive stress value CS0(Na) is preferably 230 MPa or more, more preferably 250 MPa or more, even more preferably 300 MPa or more, even more preferably 350 MPa or more, and particularly preferably 400 MPa or more. When the value of CS0(Na) is 230 MPa or more, sufficient compressive stress is likely to be introduced when this glass is chemically strengthened, and excellent strength is easily obtained. Also, when the value of CS0(Na) is relatively large, the compressive stress value CS 50 is also likely to be large, which is preferable. If the value of CS0(Na) is too large, a large tensile stress will occur inside the chemically strengthened glass, and there is a risk of fracture, so it is preferably 800 MPa or less, and more preferably 700 MPa or less.

[0080] The fracture toughness value of this glass is 0.70 MPa·m 1 / 2 or more is preferable, more preferably 0.75 MPa·m 1 / 2 or more, and even more preferably 0.80 MPa·m1 / 2 The above is particularly preferable at 0.83 MPa·m 1 / 2 That concludes the explanation. Furthermore, the fracture toughness value is typically 2.0 MPa·m. 1 / 2 The following is typical, usually 1.5 MPa·m 1 / 2 The following is true: Due to its high fracture toughness, even when large surface compressive stresses are introduced into the glass through chemical strengthening, severe fracture is less likely to occur.

[0081] Fracture toughness values ​​can be measured, for example, using the DCDC method (Acta metall.mater. Vol.43, pp.3453-3458, 1995).

[0082] The Young's modulus of this glass is preferably 80 GPa or higher, more preferably 82 GPa or higher, even more preferably 84 GPa or higher, and particularly preferably 85 GPa or higher, in order to prevent the glass from shattering easily. There is no particular upper limit to the Young's modulus, but since glass with a high Young's modulus may have low acid resistance, it is preferably 110 GPa or lower, more preferably 100 GPa or lower, and even more preferably 90 GPa or lower. The Young's modulus can be measured, for example, by the ultrasonic pulse method.

[0083] The average linear thermal expansion coefficient (thermal expansion coefficient) of this glass at 50-350°C is preferably 95 × 10⁻⁶, from the viewpoint of reducing warping after chemical strengthening. -7 / ℃ or lower, more preferably 90 × 10 -7 / ℃ or lower, more preferably 88 × 10 -7 / ℃ or lower, particularly preferably 86 × 10 -7 / ℃ or lower, most preferably 84 × 10 -7 It is below / ℃. There is no particular lower limit to the coefficient of thermal expansion, but since glass with a small coefficient of thermal expansion may be difficult to melt, the average linear thermal expansion coefficient (coefficient of thermal expansion) of this glass at 50~350℃ is, for example, 60 × 10 -7 Preferably above / ℃, more preferably 70×10 -7 / ℃ or higher, more preferably 74 × 10 -7 / ℃ or higher, more preferably 76 × 10 -7 It is above / ℃.

[0084] The glass transition temperature (Tg) is preferably 500°C or higher, more preferably 520°C or higher, and even more preferably 540°C or higher, from the viewpoint of reducing warping after chemical strengthening. For ease of float molding, the Tg is preferably 750°C or lower, more preferably 700°C or lower, even more preferably 650°C or lower, particularly preferably 600°C or lower, and most preferably 580°C or lower.

[0085] Viscosity is 10 2 The temperature (T2) at which the dPa·s temperature is obtained is preferably 1750°C or lower, more preferably 1700°C or lower, even more preferably 1675°C or lower, and particularly preferably 1650°C or lower. The temperature (T2) is an indicator of the melting temperature of the glass, and the lower the T2, the easier it tends to be to manufacture the glass. The lower limit of T2 is not particularly limited, but since glasses with a low T2 tend to have a glass transition temperature that is too low, T2 is preferably 1400°C or higher, and more preferably 1450°C or higher.

[0086] Also, the viscosity is 10 4 The temperature at which the dPa·s temperature is obtained (T4) is preferably 1350°C or lower, more preferably 1300°C or lower, even more preferably 1250°C or lower, and particularly preferably 1150°C or lower. The temperature (T4) is a guideline temperature for forming the glass into a plate, and glass with a high T4 tends to place a higher load on the forming equipment. The lower limit of T4 is not particularly limited, but glass with a low T4 tends to have a glass transition temperature that is too low, so T4 is preferably 900°C or higher, more preferably 950°C or higher, and even more preferably 1000°C or higher.

[0087] The devitrification temperature of this glass is when the viscosity is 10 4 A temperature 120°C higher or lower than the temperature at which the dPa·s temperature is obtained (T4) is preferable because devitrification is less likely to occur during molding by the float method. More preferably, the devitrification temperature is 100°C higher or lower than T4, even more preferably 50°C higher or lower than T4, and particularly preferably T4 or lower.

[0088] The softening point of this glass is preferably 850°C or lower, more preferably 820°C or lower, and even more preferably 790°C or lower. This is because a lower softening point of glass allows for a lower heat treatment temperature during bending, resulting in less energy consumption and reduced equipment load. From the viewpoint of lowering the bending temperature, a lower softening point is preferable, but for general glass, it is 700°C or higher. Glass with a softening point that is too low tends to have low strength because the stress introduced during chemical strengthening treatment is easily relaxed; therefore, a softening point of 700°C or higher is preferable. The softening point is more preferably 720°C or higher, and even more preferably 740°C or higher. The softening point can be measured by the fiber stretching method described in JIS R3103-1:2001.

[0089] For this glass, it is preferable that the crystallization peak temperature, as measured by the following measurement method, is higher than the softening point -100°C. Furthermore, it is even preferable that no crystallization peak is observed.

[0090] Specifically, approximately 70 mg of glass is crushed, ground in an agate mortar, and measured using a differential scanning calorimeter (DSC) from room temperature to 1000°C at a heating rate of 10°C / min.

[0091] When the glass is in the form of a plate (glass plate), its thickness (t) is, from the viewpoint of enhancing the effect of chemical strengthening, for example, 2 mm or less, preferably 1.5 mm or less, more preferably 1 mm or less, even more preferably 0.9 mm or less, particularly preferably 0.8 mm or less, and most preferably 0.7 mm or less. Furthermore, from the viewpoint of obtaining a sufficient effect of strength improvement through chemical strengthening treatment, the thickness is, for example, preferably 0.1 mm or more, more preferably 0.2 mm or more, even more preferably 0.3 mm or more, even more preferably 0.35 mm or more, particularly preferably 0.4 mm or more, and even more particularly preferably 0.5 mm or more.

[0092] The shape of the glass may not be flat, depending on the product and application to which it is applied. The glass plate may also have a rim shape with different thicknesses on its outer edge. Furthermore, the shape of the glass plate is not limited to this; for example, the two main surfaces do not have to be parallel to each other. Also, one or both of the two main surfaces may be curved, in whole or in part. More specifically, the glass plate may be, for example, a flat glass plate without warping, or a curved glass plate with a curved surface.

[0093] The glass according to the embodiment of the present invention can be manufactured by a general method. For example, the raw materials for each component of the glass are mixed and heated and melted in a glass melting furnace. Then, the glass is homogenized by a known method, formed into a desired shape such as a glass plate, and slowly cooled.

[0094] Examples of glass plate forming methods include the float method, press method, fusion method, and down-draw method. The float method is particularly preferred as it is suitable for mass production. Continuous forming methods other than the float method, such as the fusion method and the down-draw method, are also preferred.

[0095] Subsequently, the molded glass is ground and polished as needed to form a glass substrate. When cutting the glass substrate to a predetermined shape and size, or when chamfering the glass substrate, it is preferable to perform the cutting and chamfering before applying the chemical strengthening treatment described later, because this will allow a compressive stress layer to be formed on the edges during the subsequent chemical strengthening treatment.

[0096] <Crystallized glass> The crystallized glass according to an embodiment of the present invention (hereinafter also referred to as "this crystallized glass") is a crystallized glass having the glass composition of this glass described above.

[0097] The crystallized glass preferably contains one or more selected from lithium silicate crystals, lithium aluminosilicate crystals or lithium phosphate crystals, magnesium aluminosilicate crystals, magnesium silicate crystals, and silicate crystals. Lithium metasilicate crystals are more preferred as lithium silicate crystals. One or more selected from petalite crystals or β-spodumene crystals, α-eucryptite, and β-eucryptite are preferred as lithium aluminosilicate crystals. Lithium orthophosphate crystals are preferred as lithium phosphate crystals.

[0098] To achieve high transparency, crystallized glass containing lithium metasilicate crystals is more preferable.

[0099] Crystallized glass is obtained by heating amorphous glass having a similar composition to this glass to induce crystallization. The glass composition of crystallized glass is the same as that of amorphous glass.

[0100] Crystallized glass has a visible light transmittance (total visible light transmittance including diffusely transmitted light) of preferably 85% or more when converted to a thickness of 0.7 mm, which makes the display screen easy to see when used as cover glass for mobile phone displays. A visible light transmittance of 88% or more is more preferable, and 90% or more is even more preferable. A higher visible light transmittance is preferable, but it is usually 93% or less. For reference, the visible light transmittance of ordinary amorphous glass is about 90% or more. If the thickness of the crystallized glass is not 0.7 mm, the Lambert-Beer law can be used to calculate the visible light transmittance that would be the case for a 0.7 mm thickness from the measured transmittance. If a glass plate with thickness t [mm] has a total visible light transmittance of 100 × T [%] and a surface reflectance of 100 × R [%] on one side, then by applying the Lambert-Beer law, using a constant α, T = (1 - R) 2 There is a relationship of ×exp(-αt). From here, we can express α in terms of R, T, and t, and if we set t = 0.7 mm, then R does not change with plate thickness, so the total visible light transmittance T on a 0.7 mm basis is... 0.7 is T 0.7 = 100 × T 0.7 / t It can be calculated as / (1-R)^(1.4 / t-2)[%], where X^Y is X Y It represents. Surface reflectance can be calculated from the refractive index or measured directly. Furthermore, for glass with a thickness t greater than 0.7 mm, the thickness can be adjusted to 0.7 mm through polishing or etching, and the visible light transmittance can be measured directly.

[0101] Furthermore, the haze value is preferably 1.0% or less, more preferably 0.4% or less, even more preferably 0.3% or less, particularly preferably 0.2% or less, and most preferably 0.15% or less, when converted to a thickness of 0.7 mm. A smaller haze value is preferable, but reducing the crystallinity or grain size to reduce the haze value will decrease the mechanical strength. To increase the mechanical strength, the haze value for a thickness of 0.7 mm is preferably 0.02% or more, and more preferably 0.03% or more. The haze values ​​are measured according to JIS K7136 (2000). Furthermore, if a crystallized glass plate with thickness t[mm] has a total visible light transmittance of 100×T[%] and a haze value of 100×H[%], then by applying the Lambert-Beer law, using the constant α mentioned above, dH / dt ∝ exp(-αt) × (1-H) It can be expressed as follows. In other words, the haze value is thought to increase proportionally to the internal linear transmittance as the plate thickness increases, so the haze value H for 0.7mm is 0.7 It can be calculated using the following formula. However, "X^Y" is "X Y This represents ". H 0.7 =100 × [1-(1-H)^{((1-R) 2 -T 0.7 ) / ((1-R) 2 -T)}][%] Furthermore, in the case of glass with a plate thickness t greater than 0.7 mm, the plate thickness may be adjusted to 0.7 mm by polishing or etching, and the haze value may be measured in person.

[0102] When using tempered glass, which is made by strengthening crystallized glass, as the cover glass for a mobile phone display, it is preferable that it has a different texture and a sense of luxury compared to plastic. For this reason, the refractive index of this crystallized glass is preferably 1.52 or higher at a wavelength of 590 nm, more preferably 1.55 or higher, and even more preferably 1.57 or higher.

[0103] The crystallinity of crystallized glass is preferably 5% or more, more preferably 10% or more, even more preferably 15% or more, and particularly preferably 20% or more, in order to increase its mechanical strength. In order to increase its transparency, it is preferably 70% or less, more preferably 60% or less, and particularly preferably 50% or less. A low crystallinity is also advantageous in that it is easy to heat and bend or shape.

[0104] The crystallization rate can be calculated from the X-ray diffraction intensity using the Rietveld method. The Rietveld method is described in the "Crystal Analysis Handbook" edited by the editorial committee of the Crystallographic Society of Japan (Kyōritsu Shuppan, 1999, pp. 492-499).

[0105] The average particle size of the precipitated crystals in the crystallized glass is preferably 80 nm or less, more preferably 60 nm or less, even more preferably 50 nm or less, particularly preferably 40 nm or less, and most preferably 30 nm or less. The average particle size of the precipitated crystals can be determined from transmission electron microscope (TEM) images. The average particle size of the precipitated crystals can be estimated from scanning electron microscope (SEM) images.

[0106] The average thermal expansion coefficient of crystallized glass at 50°C to 350°C is 90 × 10⁻⁶. -7 Preferably above / ℃, more preferably 100×10 -7 / ℃ or higher, more preferably 110 × 10 -7 / ℃ or higher, particularly preferably 120 × 10 -7 / ℃ or higher, most preferably 130 × 10 -7 It is above / ℃.

[0107] If the coefficient of thermal expansion is too large, cracking may occur during the chemical strengthening process due to the difference in thermal expansion coefficients. Therefore, the average coefficient of thermal expansion between 50°C and 350°C is preferably 160 × 10⁻⁶. ―7 / ℃ or lower, more preferably 150×10 -7 / ℃ or lower, more preferably 140 × 10 -7 It is below / ℃.

[0108] Crystallized glass has high hardness because it contains crystals. Therefore, it is resistant to scratches and has excellent wear resistance. To maximize wear resistance, a Vickers hardness of 600 or higher is preferred, 700 or higher is more preferred, 730 or higher is even more preferred, 750 or higher is particularly preferred, and 780 or higher is most preferred.

[0109] If the hardness is too high, it becomes difficult to process, so the Vickers hardness of the crystallized glass is preferably 1100 or less, more preferably 1050 or less, and even more preferably 1000 or less.

[0110] The Young's modulus of crystallized glass is preferably 85 GPa or higher, more preferably 90 GPa or higher, even more preferably 95 GPa or higher, and particularly preferably 100 GPa or higher, in order to suppress warping due to strengthening during chemical strengthening. Crystallized glass may be used after polishing. For ease of polishing, the Young's modulus is preferably 130 GPa or lower, more preferably 125 GPa or lower, and even more preferably 120 GPa or lower.

[0111] The fracture toughness value of the crystallized glass is preferably 0.8 MPa·m 1 / 2 The above is more preferable at 0.85 MPa·m 1 / 2 More preferably, 0.9 MPa·m 1 / 2 That concludes the explanation. It is preferable that the fracture toughness value is equal to or greater than the above value, because when chemically strengthened, fragments are less likely to scatter when the material breaks.

[0112] This crystallized glass has the same glass composition as the glass described above. That is, this crystallized glass is obtained by heat-treating amorphous glass having the same glass composition as this glass to crystallize it. Because this crystallized glass has the same glass composition as this glass, it can be chemically strengthened to obtain excellent strength and has excellent radio wave transmittance, just like this glass.

[0113] <Chemically strengthened glass> The chemically strengthened glass according to an embodiment of the present invention (hereinafter also referred to as "this chemically strengthened glass") is obtained by chemically strengthening the above-described glass or crystallized glass. That is, the base composition of this chemically strengthened glass is the same as the glass composition of the above-described glass, and the preferred composition range is also the same. In the chemically strengthened glass, except in the case of extreme ion exchange treatment, the glass composition at a depth of 1 / 2 of the plate thickness t is the same as the base composition of the chemically strengthened glass. Furthermore, the average composition of this chemically strengthened glass is the same as the composition of the glass or crystallized glass. Here, the average composition refers to the composition obtained by analyzing a glass sample that has been finely crushed after heat treatment from the glassy state.

[0114] This chemically strengthened glass preferably has a surface compressive stress value CS0 of 300 MPa or higher, more preferably 350 MPa or higher, even more preferably 400 MPa or higher, even more preferably 450 MPa or higher, and particularly preferably 500 MPa or higher. A surface compressive stress value CS0 of 300 MPa or higher makes it easier to obtain excellent strength, and furthermore, the compressive stress value CS at a depth of 50 μm from the surface is also desirable. 50 This is preferable because it also tends to grow larger.

[0115] While a higher surface compressive stress value (CS0) generally results in greater strength, excessively high CS0 can lead to significant tensile stress within the chemically strengthened glass, potentially causing fracture. From this perspective, a surface compressive stress value (CS0) of 1000 MPa or less is preferable, and 800 MPa or less is more preferable.

[0116] In the stress profile of this chemically strengthened glass, the compressive stress value CS at a depth of 50 μm from the surface is shown. 50 The pressure is preferably 75 MPa or higher, more preferably 90 MPa or higher, even more preferably 100 MPa or higher, and particularly preferably 125 MPa or higher. 50 The larger size of the glass makes it less likely to break when chemically strengthened glass is damaged by a fall or other impact.

[0117] The internal tensile stress value (CT) of this chemically strengthened glass is preferably 80 MPa or less, and more preferably 75 MPa or less. A lower CT makes it less prone to shattering. The internal tensile stress value (CT) is preferably 50 MPa or more, more preferably 60 MPa or more, and even more preferably 65 MPa or more. A CT of the above value or higher increases the compressive stress near the surface, resulting in higher strength.

[0118] The compressive stress layer depth (DOL) of this chemically strengthened glass is preferably 0.25t or less, more preferably 0.2t or less, even more preferably 0.19t or less, and even more preferably 0.18t or less, because if it is too large relative to the thickness t (μm), it will lead to an increase in CT. Furthermore, from the viewpoint of improving strength, the DOL is preferably 0.06t or more, more preferably 0.08t or more, even more preferably 0.10t or more, and particularly preferably 0.12t or more. Specifically, for example, when the plate thickness t is 700 μm (0.7 mm), the DOL is preferably 140 μm or less, more preferably 133 μm or less. Also, the DOL is preferably 70 μm or more, more preferably 80 μm or more, and even more preferably 90 μm or more. The preferred plate thickness (t) and preferred shape of this chemically strengthened glass are the same as the preferred plate thickness (t) and preferred shape of this glass described above.

[0119] This chemically strengthened glass can be manufactured by applying a chemical strengthening treatment to the obtained glass plate, followed by washing and drying.

[0120] Chemical strengthening can be carried out by known methods. In chemical strengthening, a glass plate is brought into contact with a molten metal salt (e.g., potassium nitrate) containing metal ions with a large ionic radius (typically K ions) by immersion or other means. As a result, metal ions with a small ionic radius (typically Na ions or Li ions) in the glass plate are replaced by metal ions with a large ionic radius (typically K ions for Na ions, and Na ions for Li ions).

[0121] Chemical strengthening (ion exchange treatment) can be performed, for example, by immersing a glass plate in a molten salt such as potassium nitrate heated to 360-600°C for 0.1-500 hours. Preferably, the heating temperature of the molten salt is 375-500°C, and the immersion time of the glass plate in the molten salt is 0.3-200 hours.

[0122] Examples of molten salts used for chemical strengthening treatment include nitrates, sulfates, carbonates, and chlorides. Examples of nitrates include lithium nitrate, sodium nitrate, potassium nitrate, cesium nitrate, and silver nitrate. Examples of sulfates include lithium sulfate, sodium sulfate, potassium sulfate, cesium sulfate, and silver sulfate. Examples of carbonates include lithium carbonate, sodium carbonate, and potassium carbonate. Examples of chlorides include lithium chloride, sodium chloride, potassium chloride, cesium chloride, and silver chloride. These molten salts may be used individually or in combination.

[0123] In the present invention, the processing conditions for the chemical strengthening treatment should be selected appropriately, taking into consideration the properties and composition of the glass, the type of molten salt, and the chemical strengthening characteristics such as the desired surface compressive stress and the depth of the compressive stress layer in the final chemically strengthened glass.

[0124] Furthermore, in this invention, chemical strengthening treatment may be performed only once, or multiple chemical strengthening treatments (multi-stage strengthening) may be performed under two or more different conditions. For example, as the first stage of chemical strengthening treatment, chemical strengthening treatment is performed under conditions in which DOL is large and CS is relatively small. Subsequently, as the second stage of chemical strengthening treatment, chemical strengthening treatment is performed under conditions in which DOL is small and CS is relatively high. This allows for increasing the CS of the outermost surface of the chemically strengthened glass while suppressing the internal tensile stress area (St) and keeping the internal tensile stress (CT) low.

[0125] This glass is particularly useful as cover glass for mobile devices such as mobile phones, smartphones, personal digital assistants (PDAs), and tablet devices. Furthermore, it is also useful for applications not intended for portability, such as cover glass for display devices like televisions (TVs), personal computers (PCs), and touch panels; elevator walls; building materials such as walls of houses and buildings (full-surface displays); window glass; tabletops; interiors of automobiles and airplanes, etc., and as cover glass for these; and for enclosures with curved shapes other than flat sheets, which are formed by bending or molding. [Examples]

[0126] The present invention will be described below with reference to examples, but the present invention is not limited thereto. The glass raw materials were mixed to achieve the compositions shown in Tables 1-6, expressed as molar percentages based on oxides, and weighed to produce 400g of glass. The mixed raw materials were then placed in a platinum crucible and melted in an electric furnace at 1500-1700°C for approximately 3 hours, after which they were degassed and homogenized. In the tables, Mg+Ca+Sr+Ba means [MgO]+[CaO]+[SrO]+[BaO].

[0127] The obtained molten glass was poured into a metal mold and held at a temperature approximately 50°C above the glass transition point for 1 hour. After that, it was cooled to room temperature at a rate of 0.5°C / min to obtain a glass block. The obtained glass block was cut and ground, and finally both sides were mirror-polished to obtain a glass plate with a thickness of 600 μm. Examples 1 to 50 are examples of the present glass, and Examples 51 to 53 are comparative examples.

[0128] For each example of glass, the relative permittivity ε' and dielectric loss tangent tanδ were measured at 20°C and 10 GHz. Measurements were performed using a cavity resonator and a vector network analyzer, following the method specified in JIS R1641 (2007). The measurement frequency was set to 20°C and 10 GHz, which are the resonant frequencies of air in the cavity resonator. The results are shown in Tables 1-6.

[0129] Furthermore, each glass was chemically strengthened by immersion in a 100% sodium nitrate salt solution at 450°C for 1 hour. The surface compressive stress value CS0(Na) and compressive stress depth DOL after chemical strengthening were measured using a scattered light photoelastic stress meter SLP-1000 manufactured by Orihara Seisakusho Co., Ltd. The results are shown in Tables 1-6. In the tables, blank spaces indicate that measurements were not taken.

[0130] Figure 1 shows the relationship between the value of parameter X and the surface compressive stress value CS0(Na) after chemical strengthening for the glasses in Examples 1 to 50. From Figure 1, it can be seen that there is a tendency for CS0(Na) to increase as the value of parameter X increases.

[0131] Figure 2 shows the relationship between the value of parameter Y and the relative permittivity at 20°C and 10GHz for the glasses in Examples 1 to 50. From Figure 2, it can be seen that the smaller the parameter Y, the lower the relative permittivity at 20°C and 10GHz tends to be.

[0132] Figure 3 shows the relationship between the value of parameter Z and the dielectric loss tangent at 20°C and 10GHz for the glasses in Examples 1 to 50. From Figure 3, it can be seen that the smaller the parameter Z, the smaller the dielectric loss tangent at 20°C and 10GHz tends to be.

[0133] [Table 1]

[0134] [Table 2]

[0135] [Table 3]

[0136] [Table 4]

[0137] [Table 5]

[0138] [Table 6]

[0139] The glass samples in Examples 1 to 50, which are examples of the case studies, had surface compressive stress values ​​exceeding 230 MPa after chemical strengthening, demonstrating that excellent strength was obtained through chemical strengthening. Furthermore, the glasses in Examples 1 to 50 exhibited excellent relative permittivity ε' and dielectric loss tangent tanδ at 20°C and 10GHz, confirming their superior radio wave transmission properties.

[0140] On the other hand, the comparative examples 51 and 52 did not contain lithium ions, making it difficult to increase their strength through chemical strengthening using sodium salts. Furthermore, the glasses in 51 and 52 had high dielectric constants and tanδ, resulting in poor radio wave transparency. In addition, although the glass in 53 had a small tanδ, the surface compressive stress value during chemical strengthening was insufficient, resulting in a failure to achieve both strength and radio wave transparency.

[0141] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2020-115920, filed 3 July 2020, the contents of which are incorporated herein by reference.

Claims

1. Expressed as a mole percentage based on oxides, SiO ２ 50.0-75.0% Al ２ O ３ を7.5~25.0%、 B ２ O ３ 8.0-25.0%, Li ２ Oを6.5~20.0%、 Na ２ Oを1.5~10.0%、 K ２ O at 0-4.0%, MgO at 1.0-20.0%, P ２ O ５ is 0 to 1%, One or more elements selected from MgO, CaO, SrO, and BaO, totaling 1.0-20.0%. TiO ２ It contains 0-5.0% of MgO, CaO, SrO, BaO, Li ２ O, Na ２ O, K ２ The content of each component of O in mole percentage form based on oxides: [MgO], [CaO], [SrO], [BaO], [Li ２ O] [Na ２ O], [K ２ Using O, the value of Y calculated based on the following formula is 17.5 or less. Al ２ O ３ , B ２ O ３ Li ２ O, Na ２ Content of each component of O in molar percentage based on oxides [Al ２ O ３ ] [B ２ O ３ ], [Li ２ O] [Na ２ Glass in which the value of Z calculated using the following formula is 12.0 or less. Y=1.2×([Mg0]+[Ca0]+[Sro]+[Ba0])+1.6×([Li] ２ O]+[Na ２ O]+[K ２ O] Z=3×[AS ２ O ３ ]-3×[B ２ O ３ ]-2×[L) ２ O]+4×[N ２ O]

2. Al ２ O ３ , MgO, Li ２ O, Na ２ O, K ２ Content of each component of O in molar percentage based on oxides [Al ２ O ３ ], [MgO], [Li ２ O] [Na ２ O], [K ２ The glass according to claim 1, wherein the value of X calculated using the following formula is 30.0 or more. ^=3×[AS ２ O ３ ]+[MO]+[L- ２ O]-2×([N ２ O]+[K ２ O])

3. Expressed as a mole percentage based on oxides, SiO ２ 55.0-75.0% Al ２ O ３ を9.1~25.0%、 B ２ O ３ 0-14.0%, Li ２ Oを7.5~12.5%、 Na ２ Oを3.6~5.5%、 K ２ O at 0-2.0%, One or more elements selected from MgO, CaO, SrO, and BaO, totaling 0-13.0%. It contains 0-8.0% ZnO, Al ２ O ３ , B ２ O ３ , MgO, Li ２ O, Na ２ O, K ２ Content of each component of O in molar percentage based on oxides [Al ２ O ３ ] [B ２ O ３ ], [MgO], [Li ２ O] [Na ２ O], [K ２ Using O, the value of X calculated based on the following formula is 31.3 or greater, and the value of Z is 12.0 or less, and the glass (however, Pr ２ O ３ Glass containing WO ３ and MoO ３ (Excluding glass containing at least one of the following.) ^=3×[AS ２ O ３ ]+[MO]+[L- ２ O]-2×([N ２ O]+[K ２ O]) Z=3×[AS ２ O ３ ]-3×[B ２ O ３ ]-2×[L) ２ O]+4×[N ２ O]

4. Expressed as a mole percentage based on oxides, SiO ２ 50.0-65.9% Al ２ O ３ を9.0~25.0%、 B ２ O ３ 0-20.0%, Li ２ Oを6.5~14.5%、 Na ２ Oを2.5~10.0%、 K ２ O at 0-4.0%, One or more elements selected from MgO, CaO, SrO, and BaO, totaling 0-20.0%. TiO ２ It contains 0-3.0% of Al ２ O ３ , B ２ O ３ , MgO, CaO, SrO, BaO, Li ２ O, Na ２ O, K ２ Content of each component of O in molar percentage based on oxides [Al ２ O ３ ] [B ２ O ３ ], [MgO], [CaO], [SrO], [BaO], [Li ２ O] [Na ２ O], [K ２ Using O, the value of X calculated based on the following formula is 35.0 or greater, the value of Y is 18.6 or greater, the value of Z is 13.0 or less, and the sum of the values ​​of Y and Z is 35.0 or less, and this is a glass for cover glass (however, WO ３ and MoO ３ (Excluding glass containing at least one of the following.) ^=3×[AS ２ O ３ ]+[MO]+[L- ２ O]-2×([N ２ O]+[K ２ O]) Y=1.2×([Mg0]+[Ca0]+[Sro]+[Ba0])+1.6×([Li] ２ O]+[Na ２ O]+[K ２ O] Z=3×[AS ２ O ３ ]-3×[B ２ O ３ ]-2×[L) ２ O]+4×[N ２ O]

5. The glass according to any one of claims 1 to 4, wherein the plate thickness (t) is 100 μm or more and 2000 μm or less.

6. The base composition is expressed as a mole percentage based on oxides. SiO ２ 50.0-75.0% B ２ O ３ 8.0-25.0%, Al ２ O ３ を7.5~25.0%、 Li ２ Oを6.5~20.0%、 Na ２ Oを1.5~10.0%、 K ２ O at 0-4.0%, MgO at 1.0-20.0%, P ２ O ５ 0-1%, One or more elements selected from MgO, CaO, SrO, and BaO, totaling 1.0-20.0%. TiO ２ It contains 0-5.0% of MgO, CaO, SrO, BaO, Li ２ O, Na ２ O, K ２ The content of each component of O in mole percentage form based on oxides: [MgO], [CaO], [SrO], [BaO], [Li ２ O] [Na ２ O], [K ２ Using O, the value of Y calculated based on the following formula is 17.5 or less. Al ２ O ３ , B ２ O ３ Li ２ O, Na ２ Content of each component of O in molar percentage based on oxides [Al ２ O ３ ] [B ２ O ３ ], [Li ２ O] [Na ２ Chemically strengthened glass in which the value of Z calculated using the following formula is 12.0 or less. Y=1.2×([Mg0]+[Ca0]+[Sro]+[Ba0])+1.6×([Li] ２ O]+[Na ２ O]+[K ２ O] Z=3×[AS ２ O ３ ]-3×[B ２ O ３ ]-2×[L) ２ O]+4×[N ２ O]

7. Surface compressive stress value CS ０ The chemically strengthened glass according to claim 6, wherein the pressure is 300 MPa or more.

8. Compressive stress value CS at a depth of 50 μm from the glass surface. ５０ The chemically strengthened glass according to claim 6 or 7, wherein the pressure is 75 MPa or more and the plate thickness (t) is 300 μm or more.

9. A chemically strengthened glass according to any one of claims 6 to 8, wherein the compressive stress layer depth DOL is 80 μm or more and the plate thickness (t) is 350 μm or more.

10. A crystallized glass having the glass composition of the glass described in any one of claims 1 to 4.

11. The crystallized glass according to claim 10, wherein the visible light transmittance is 88% or more when converted to a thickness of 0.7 mm.

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