Chemically strengthened crystallized glass, method for producing chemically strengthened crystallized glass, and cover glass

Abstract

Provided is a chemically strengthened crystallized glass which has excellent moisture resistance.　With respect to a Raman spectrum of the chemically strengthened crystallized glass obtained by Raman spectrometry, when A1 is the peak area of 380-440 cm-1 and A2 is and the peak area of 520-570 cm-1, the maximum value of A2 / A1 in the depth range of 0-3 µm from the surface is 2.2 or less. The chemically strengthened crystallized glass contains Li2Si2O5 crystals.

Description

Chemically strengthened crystallized glass, method for manufacturing chemically strengthened crystallized glass, cover glass

[0001] This invention relates to chemically strengthened crystallized glass and cover glass containing chemically strengthened crystallized glass. The invention also relates to a method for manufacturing chemically strengthened crystallized glass.

[0002] In recent years, cover glass has been used to protect and enhance the aesthetics of display devices such as mobile phones, smartphones, and tablet devices. Cover glass used in these applications requires excellent strength to suppress damage from impacts, etc. Furthermore, such cover glass is sometimes used to protect solar power generation modules (solar cell modules). Cover glass used in solar power generation modules plays a role in protecting the modules from flying objects, etc., and it is believed that a reduction in the rate of damage to solar power generation modules will ultimately contribute to the reduction of greenhouse gases.

[0003] Conventionally, a method has been known to increase the surface strength of glass by chemically strengthening it through immersion in a molten salt such as potassium nitrate. For example, Patent Document 1 describes obtaining chemically strengthened glass by immersing glass in a molten salt. Patent Document 1 also describes using crystallized glass, in which crystals are precipitated within the glass, as the glass to be used for chemical strengthening.

[0004] International Publication No. 2024 / 014305

[0005] Cover glass is used for purposes such as protecting display devices or solar power generation modules, and is therefore typically used in contact with moisture-containing air. In other words, it is required that the cover glass does not deteriorate during use, i.e., that it has moisture resistance. The present inventors investigated glass obtained by chemically strengthening conventional crystallized glass, such as that described in Patent Document 1 (hereinafter also referred to as "chemically strengthened crystallized glass"), and found that there is room for improvement in the moisture resistance of chemically strengthened crystallized glass.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a chemically strengthened crystallized glass having excellent moisture resistance. Another object of the present invention is to provide a method for producing a chemically strengthened crystallized glass and a cover glass.

[0007] As a result of intensive studies by the present inventors on the above problems, it has been found that when the peak area ratio in a predetermined wave number region is adjusted to a predetermined range in the Raman spectrum, the moisture resistance is excellent, and the present invention has been completed.

[0008] That is, the inventors have found that the above problems can be solved by the following configuration. [1] In the Raman spectrum obtained by performing Raman spectroscopic measurement, when the peak area at 380 to 440 cm －１ is A1 and the peak area at 520 to 570 cm －１ is A2, the maximum value of A2 / A1 in the range of 0 to 3 μm from the surface is 2.2 or less, and a chemically strengthened crystallized glass containing Li ２ Si ２ O ５ crystals. [2] When A2 / A1 at a depth of 1 μm from the surface is R １μｍ and A2 / A1 at a depth of 10 μm from the surface is R １０μｍ , the chemically strengthened crystallized glass according to [1], wherein R １μｍ / R １０μｍ is 0.7 to 1.3. [3] The chemically strengthened crystallized glass according to [1] or [2], having a Young's modulus of 105 GPa or more. [4] The chemically strengthened crystallized glass according to any one of [1] to [3], having a fracture toughness value K ＩＣ of 1.30 MPa·m １／２ or more. [5] The chemically strengthened crystallized glass according to any one of [1] to [4], having a depth of a compressive stress layer measured using a scattered light photoelastic stress gauge of 30 μm or more. [6] The chemically strengthened crystallized glass according to any one of [1] to [5], having no Na ion diffusion layer. [7] The chemically strengthened crystallized glass according to any one of [1] to [6], having an absolute value of a tensile stress value at the center position of the plate thickness of 50 MPa or less. [8] The composition at the center position of the plate thickness is expressed in terms of molar percentage based on oxides, and SiO ２60.0-75.0%, Al ２ O ３ 2.0-6.0%, P ２ O ５ Li ２ 20.0-30.0% O, Na ２ O at 0.0-5.0%, K ２ O 0.0-1.0%, MgO 0.0-2.0%, CaO 0.0-2.0%, SrO 0.0-1.0%, ZrO ２ 1.0-5.0%, SnO ２ It contains 0.0 to 1.0% of Y ２ O ３ A chemically strengthened crystallized glass according to any one of [1] to [7], which substantially does not contain [1]. [9] A chemically strengthened crystallized glass according to any one of [1] to [8], wherein the K ion diffusion depth is 7 μm or more from the surface.

[10] In the Raman spectrum obtained by Raman spectroscopy, 380 to 440 cm⁻¹ －１ Let A1 be the peak area, and the range be 520-570 cm². －１ When the peak area is taken as A2, the maximum value of A2 / A1 in the range from the surface to a depth of 0 to 3 μm is 2.2 or less, and Li ２ Si ２ O ５ A method for producing chemically strengthened crystallized glass, comprising chemically strengthening a crystallized glass containing crystals by contacting it with the following molten salt A or molten salt B to obtain chemically strengthened crystallized glass. Molten salt A: A molten salt containing 30% by mass or more of K salt, 30% by mass or more of Na salt, and 0.02% by mass or more of Li salt. Molten salt B: A molten salt containing 95% by mass or more of K salt.

[11] The K salt contained in the above molten salt A and above molten salt B is KNO ３ Therefore, the Na salt contained in the above molten salt A is NaNO ３ Therefore, the Li salt contained in the above molten salt A is LiNO ３ The method for producing chemically strengthened crystallized glass as described in

[10] .

[12] The method for producing chemically strengthened crystallized glass as described in

[10] or

[11] , wherein the Young's modulus of the chemically strengthened crystallized glass is 105 GPa or more.

[13] The fracture toughness value K of the chemically strengthened crystallized glass. ＩＣ However, 1.30 MPa·m１／２ The method for producing chemically strengthened crystallized glass according to any one of

[10] to

[12] .

[14] The method for producing chemically strengthened crystallized glass according to any one of

[10] to

[13] , wherein the compressive stress layer depth measured using a scattered light photoelastic stress meter in the obtained chemically strengthened crystallized glass is 30 μm or more.

[15] The method for producing chemically strengthened crystallized glass according to any one of

[10] to

[14] , wherein the obtained chemically strengthened crystallized glass does not have a Na ion diffusion layer.

[16] The method for producing chemically strengthened crystallized glass according to any one of

[10] to

[15] , wherein the absolute value of the tensile stress at the center of the plate thickness in the obtained chemically strengthened crystallized glass is 50 MPa or less.

[17] The method for producing chemically strengthened crystallized glass according to any one of

[10] to

[16] , wherein when the chemically strengthened crystallized glass is brought into contact with the molten salt B to perform chemical strengthening, the temperature of the molten salt B is 430°C or higher and the chemical strengthening time is 200 minutes or more.

[18] When chemical strengthening is performed by bringing the above-mentioned chemically strengthened crystallized glass into contact with the above-mentioned molten salt B, the temperature of the above-mentioned molten salt B is set to T Ｋ , the processing time for the above K salt strengthening treatment is t Ｋ A method for manufacturing chemically strengthened crystallized glass according to any one of

[10] to

[17] , wherein the G value obtained by the formula (PI) described later is 4.5 to 10.0.

[19] A method for manufacturing chemically strengthened crystallized glass according to any one of

[10] to

[16] , wherein when the above-mentioned crystallized glass for chemical strengthening is brought into contact with the above-mentioned molten salt A to perform chemical strengthening, the temperature of the above-mentioned molten salt A is 430°C or higher and the chemical strengthening time is 150 minutes or more.

[20] When the above-mentioned crystallized glass for chemical strengthening is brought into contact with the above-mentioned molten salt A to perform chemical strengthening, the temperature of the above-mentioned molten salt A is T Ｋ , the processing time for the above K salt strengthening treatment is t Ｋ A method for producing chemically strengthened crystallized glass according to any one of

[10] to

[16] , wherein the G value obtained by the formula (PI) described later is 3.8 to 9.5.

[21] The composition of the above chemically strengthened crystallized glass is expressed as a mole percentage based on oxides, SiO ２ 60.0-75.0%, Al ２ O ３2.0-6.0%, P ２ O ５ Li ２ 20.0-30.0% O, Na ２ O at 0.0-5.0%, K ２ O 0.0-1.0%, MgO 0.0-2.0%, CaO 0.0-2.0%, SrO 0.0-1.0%, ZrO ２ 1.0-5.0%, SnO ２ It contains 0.0 to 1.0% of Y ２ O ３ A method for producing chemically strengthened crystallized glass according to any one of

[10] to

[20] , which substantially does not include [1].

[22] A cover glass comprising the chemically strengthened crystallized glass according to any one of [1] to [9].

[23] The cover glass according to

[22] , which is a cover glass for a display.

[0009] According to the present invention, chemically strengthened crystallized glass with excellent moisture resistance can be provided. Furthermore, according to the present invention, a method for manufacturing chemically strengthened crystallized glass and a cover glass can also be provided.

[0010] Fracture toughness value K by DCDC method ＩＣ This is an explanatory diagram of the sample used for measurement. Fracture toughness value K by DCDC method. ＩＣ The stress intensity factor K1 (unit: MPa・m) used in the measurement １／２ This figure shows the K1-v curve, which illustrates the relationship between the crack growth rate v (unit: m / s) and the crack propagation rate v.

[0011] The present invention will now be described in detail. The following description of the constituent elements may be based on a typical embodiment of the present invention, but the present invention is not limited to such embodiments and can be modified and implemented as such without departing from the spirit of the invention.

[0012] In this specification, "chemically strengthened crystallized glass" refers to crystallized glass that has undergone chemical strengthening treatment. Furthermore, "crystallized glass for chemical strengthening" refers to crystallized glass before chemical strengthening treatment.

[0013] In this specification, the glass composition of chemically strengthened crystallized glass is sometimes referred to as the matrix glass composition of the chemically strengthened crystallized glass. In chemically strengthened crystallized glass, a compressive stress layer is usually formed on the glass surface due to ion exchange; therefore, the glass composition of the portion that has not undergone ion exchange (for example, at the center of the plate thickness) is the same as the matrix glass composition of the chemically strengthened crystallized glass. In this specification, the glass composition is expressed in mole percentages based on oxides, and mole% may be simply written as %. Furthermore, the "~" indicating a numerical range is used to mean that the values ​​written before and after it are included as the lower and upper limits, respectively.

[0014] In glass composition, "substantially absent" means that, excluding unavoidable impurities contained in the raw materials, etc., it does not mean that the impurities are not intentionally included. Specifically, for components other than those listed in the glass composition, for example, less than 0.1 mol% is preferred, 0.08 mol% or less is more preferred, and 0.05 mol% or less is even more preferred.

[0015] In this specification, "stress profile" refers to a profile that represents the compressive stress value with respect to the depth from the glass surface as a variable. A negative compressive stress value indicates tensile stress.

[0016] In this specification, the compressive stress layer depth is defined as the depth to which the compressive stress value becomes zero.

[0017] In this specification, "fracture toughness value K" ＩＣ The stress intensity factor K1 (unit: MPa・m) is measured using the DCDC method [Reference: M. Y. He, M. R. Turner and A. G. Evans, Acta Metal. Mater. 43 (1995) 3453.]. Specifically, using a sample with the shape shown in Figure 1 and a SHIMADZU Autograph AGS-X5KN, the stress intensity factor K1 (unit: MPa・m) is measured as shown in Figure 2. １／２ The K1-v curve, which shows the relationship between the stress intensity factor K1 and the crack propagation rate v (unit: m / s), was measured. The obtained data for Region III was then regression-extrapolated using a linear equation, and the fracture toughness value K1 at 0.1 m / s was obtained. ＩＣ Let's assume that.

[0018] <Chemically strengthened crystallized glass> The chemically strengthened crystallized glass of the present invention has a Raman spectrum obtained by Raman spectroscopy that shows a range of 380 to 440 cm⁻¹. －１ Let A1 be the peak area, and the range be 520-570 cm². －１ When the peak area is denoted as A2, the maximum value of A2 / A1 in the range of 0 to 3 μm from the surface is 2.2 or less. Furthermore, the chemically strengthened crystallized glass of the present invention is Li ２ Si ２ O ５ Contains crystals.

[0019] The mechanism by which the chemically strengthened crystallized glass of the present invention exhibits superior moisture resistance is not entirely clear, but the inventors speculate as follows. When the inventors investigated the moisture resistance of chemically strengthened crystallized glass, they found that chemically strengthened crystallized glass with poor moisture resistance showed the formation of foreign matter on the surface after moisture resistance testing. Through diligent investigation, the inventors discovered that when the above-mentioned A2 / A1 is within a predetermined range at a predetermined depth from the surface, the formation of the above-mentioned foreign matter is suppressed, resulting in superior moisture resistance. Note that in Raman spectroscopy, the range was 380-440 cm⁻¹. －１ The peak, and 520-570 cm －１ The peak is Li ２ Si ２ O ５ This peak is thought to originate from (lithium disilicate). Our investigations have shown that Li is produced by the chemical strengthening process. ２ Si ２ O ５ It was suggested that the state of Li can change, and that depending on the state, it may affect moisture resistance. The chemically strengthened crystallized glass of the present invention is Li ２ Si ２ O ５ Because it contains crystals, scratches on the surface are less likely to propagate inside the glass, resulting in superior strength and other properties.

[0020] The chemically strengthened crystallized glass of the present invention will be described in detail below.

[0021] [Raman Spectrum] The chemically strengthened crystallized glass of the present invention satisfies the above-mentioned requirements with respect to the Raman spectrum. In this specification, Raman spectroscopy measurements are performed using a micro-laser Raman spectrometer (Horiba, Ltd., LabRAM HR Evolution) and the following conditions are met for measurement and analysis. The horizontal axis of the Raman spectroscopy measurement is the Raman shift (unit: cm). －１ A Raman spectrum is obtained, with the vertical axis representing the Raman scattering intensity. The measurement conditions are as follows: • Excitation light wavelength: 532 nm • Measurement Raman shift range: 0–1700 cm －１ • Confocal hole: 10 μm • Excitation light output: 30 mW • Exposure time: 4 seconds • Number of integrations: 2 • Grating: 600 lines / mm (phrase wavelength 500 nm) • Baseline creation method: 1400-1600 cm －１ The baseline is established by offsetting the average scattering intensity at 0. Furthermore, with the above measuring device, by modulating the focal position, non-destructive depth-direction Raman spectroscopy measurements can be performed from the surface of chemically strengthened crystallized glass. Specifically, in this specification, Raman spectroscopy measurements are performed using the above device at 0.1 μm intervals in the range of 0 to 20 μm.

[0022] In the obtained Raman spectrum, 380–440 cm⁻¹ －１ The peak area is calculated and designated as A1. When calculating the peak area, the difference between the baseline intensity of each measured wavenumber and the Raman scattering intensity of each measured wavenumber is taken, and the value obtained by multiplying this difference by the difference to the next measured wavenumber is 380 to 440 cm². －１ The calculation is performed within the range of 520-570 cm. －１ The peak area is calculated similarly and designated as A2. A1 and A2 are calculated for each Raman spectrum measured in the depth direction. As described above, in the chemically strengthened crystallized glass of the present invention, the maximum value of A2 / A1 in the range of 0 to 3 μm from the surface is 2.2 or less. Preferably, the maximum value of A2 / A1 in the range of 0 to 3 μm from the surface is 2.1 or less. Also, the maximum value of A2 / A1 in the range of 0 to 3 μm from the surface is often 1.0 or more, preferably 1.3 or more, and more preferably 1.5 or more.

[0023] Also, the above A2 / A1 at a depth of 1 μm from the surface and the above A2 / A1 at a depth of 10 μm from the surface can be calculated in the same manner. Here, let the above A2 / A1 at a depth of 10 μm from the surface be R １０μｍ and the above A2 / A1 at a depth of 1 μm from the surface be R １μｍ . When this is done, R １μｍ / R １０μｍ is often 0.5 or more, preferably 0.7 or more, and more preferably 0.8 or more. Also, the above R １μｍ / R １０μｍ is often 1.5 or less, preferably 1.3 or less, and more preferably 1.1 or less.

[0024] Also, in the obtained Raman spectrum, the wavenumber showing the strongest scattering intensity in the range of 380 to 440 cm －１ is preferably 390 cm －１ or more, and more preferably 400 cm －１ or more. Also, the wavenumber showing the strongest scattering intensity in the range of 380 to 440 cm －１ is preferably 430 cm －１ or less, and more preferably 420 cm －１ or less. Also, in the obtained Raman spectrum, the wavenumber showing the strongest scattering intensity in the range of 520 to 570 cm －１ is preferably 525 cm[[ID=3D]] －１ or more, more preferably 530 cm －１ or more, and even more preferably 540 cm －１ or more. Also, the wavenumber showing the strongest scattering intensity in the range of 520 to 570 cm －１ is preferably 570 cm －１ or less, and more preferably 560 cm －１ or less. Further, in the obtained Raman spectrum, the wavenumber showing the strongest scattering intensity in the range of 520 to 600 cm －１ is preferably 530 cm －１ or more, and more preferably 540 cm －１ or more. Also, the wavenumber showing the strongest scattering intensity in the range of 520 to 600 cm －１ is preferably 590 cm －１The following is preferable: 580 cm －１ The following is more preferable: 570 cm －１ The following is more preferable: 560 cm －１ The following is the most preferable.

[0025] Furthermore, in the obtained Raman spectrum, the range of 450–520 cm² was found to further improve moisture resistance. －１ It is preferable that there is no peak in the range of 460 to 510 cm. －１ It is more preferable that there is no peak in the range of 1000-1080 cm. Furthermore, in terms of further improving moisture resistance, 1000-1080 cm is preferable. －１ It is preferable that there is no peak in the range of 1010 to 1070 cm. －１ It is more preferable that there is no peak in the range of 1020 to 1060 cm. －１ It is even more preferable that there is no peak in the range of 1030 to 1055 cm. －１ It is particularly preferable that there are no peaks in the range described above. The absence of peaks in each of the above ranges means 1400–1600 cm. －１ The average value of the scattering intensity in I Ｂ In that case, I Ｂ This means that there are no peaks showing a scattering intensity of more than three times that of 450-520 cm. －１ Within the scope of I Ｂ It is preferable that the number of peaks showing a scattering intensity of more than three times is zero. Also, 1000-1080 cm －１ Within the scope of I Ｂ It is preferable that the number of peaks showing a scattering intensity of three times or more is zero.

[0026] [Crystal species] The chemically strengthened crystallized glass of the present invention is Li ２ Si ２ O ５ Contains crystals. ２ Si ２ O ５ It is also called lithium disilicate. The chemically strengthened crystallized glass of the present invention is Li ２ Si ２ O ５It may also contain other crystals. The chemically strengthened crystallized glass of the present invention may contain Li ２ Si ２ O ５ As for crystals other than crystalline materials, one or more crystals selected from the group consisting of lithium silicate crystals, lithium aluminosilicate crystals, and lithium phosphate crystals are preferred, and one or more crystals selected from the group consisting of lithium silicate crystals and lithium aluminosilicate crystals are more preferred. As for lithium silicate crystals, lithium metasilicate (Li ２ SiO ３ ) Crystals are preferred. Lithium phosphate crystals include lithium orthophosphate (Li ３ PO ４ ) Crystals are preferred. As lithium aluminosilicate crystals, β-spodumene (LiAlSi ２ O ６ ) crystal, β-quartz solid solution (LiAlSiO ４ ) Crystal, petalite (LiAlSi ４ O １０ ) Crystals, etc. are preferred.

[0027] The crystallinity of the chemically strengthened crystallized glass of the present invention is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, and particularly preferably 25% or more, in terms of improving mechanical strength. Furthermore, in order to increase transparency, it is preferably 85% or less, more preferably 75% or less, and even more preferably 70% or less. A low crystallinity is also advantageous in that it is easy to heat and bend or shape. The crystallinity 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 (Kyoritsu Shuppan, 1999, pp. 492-499). Among the crystals contained in the chemically strengthened crystallized glass of the present invention, Li ２ Si ２ O ５ The proportion of crystals is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. Li ２ Si ２ O ５The proportion of crystals may be 100% by mass. That is, the crystals contained in the chemically strengthened crystallized glass of the present invention are Li ２ Si ２ O ５ It may be just the crystal. Li contained in the crystal ２ Si ２ O ５ The proportion of crystals can be analyzed using the method described above.

[0028] [K-ion diffusion depth] In the chemically strengthened crystallized glass of the present invention, it is also preferable that the K-ion diffusion depth is 7 μm or more. The above K-ion diffusion depth is obtained from the K-profile in the thickness direction of the chemically strengthened crystallized glass obtained by analysis with an electron probe microanalyzer. The method for obtaining the K-profile will be described in detail below.

[0029] The K profile described above is obtained by analysis using an Electron Probe Microanalyzer (EPMA). In this invention, the K profile in the thickness direction of chemically strengthened crystallized glass is obtained by the following method. First, the chemically strengthened crystallized glass is embedded in resin, a cross-section is prepared on a plane parallel to the thickness direction of the chemically strengthened crystallized glass, and the cross-section is mirror-polished to obtain a sample for measurement. The surface of the cross-section of the obtained sample of chemically strengthened crystallized glass is analyzed with EPMA. For EPMA analysis, a JEOL JXA-8500F is used. In EPMA analysis, line scan analysis is performed along the thickness direction of the chemically strengthened crystallized glass of the sample for measurement. Detailed measurement conditions follow the method described in the examples below. From the above measurement, a K profile is obtained in which the horizontal axis is depth (μm) and the vertical axis is the K content (mol%) relative to the total element content contained in the chemically strengthened crystallized glass. The K profile of the chemically strengthened crystallized glass of the present invention often takes a maximum value at a depth of 0 to 5 μm, from which the content decreases toward the center of the plate thickness, and then becomes constant.

[0030] The above K ion diffusion depth refers to the depth at which the K profile begins to rise when viewed from the center of the plate thickness toward the surface. Specifically, the K ion diffusion depth is determined by the following method. First, the value of the K content at which the above constant is determined. Ｋａｖｅ Let's assume that C Ｋａｖｅ For example, C is the average value of the K content in a 20 μm width at the center of the plate thickness. Also, C is the standard deviation of the K content in the region where the K content is constant. Ｋσ For example, the standard deviation of the K content in a width of 20 μm at the center of the plate thickness is C Ｋσ Let's assume that, when viewed from the center of the plate thickness toward the surface, the K content is first found to be C Ｋａｖｅ +3・C Ｋσ The depth to which this occurs is defined as the K ion diffusion depth.

[0031] As described above, the K ion diffusion depth is preferably 7 μm or more, may be 10 μm or more, or 12 μm or more. The K ion diffusion depth is often 30 μm or less, and preferably 20 μm or less. The K ion diffusion depth can be adjusted by the conditions of the chemical strengthening treatment described later, and the composition of the chemically strengthened crystallized glass used for chemical strengthening.

[0032] [Na ion diffusion depth] In the chemically strengthened crystallized glass of the present invention, it is also preferable that there is no Na ion diffusion layer. The Na ion diffusion layer refers to the layer from the surface to the Na ion diffusion depth which can be measured in the same manner as the K ion diffusion depth described above. Here, "not having a Na ion diffusion layer" means that the Na ion diffusion depth is 0 μm. A method for obtaining chemically strengthened crystallized glass with a Na ion diffusion depth of 0 μm (not having a Na ion diffusion layer) is to perform a chemical strengthening treatment using a molten salt that does not contain Na salt, as described later.

[0033] In the chemically strengthened crystallized glass of the present invention, the Na ion diffusion depth is preferably t / 2 or less, more preferably t / 3 or less, and even more preferably 3t / 10 or less, when the thickness of the chemically strengthened crystallized glass plate is t (unit: μm). Furthermore, as described above, the Na ion diffusion depth is preferably 0 μm. The above Na ion diffusion depth may be t / 7 or more, t / 5 or more, or 7t / 30 or more.

[0034] [Compressive Stress] The compressive stress of chemically strengthened crystallized glass can be measured using a scattered light photoelastic stymeter. Using a scattered light photoelastic stymeter makes it easy to obtain the compressive stress distribution in the depth direction. Hereinafter, the stress profile obtained using a scattered light photoelastic stymeter will also be called the "SLP stress profile". A stress profile is a profile that represents the compressive stress value with depth from the glass surface as a variable. A negative compressive stress value indicates tensile stress.

[0035] In the chemically strengthened crystallized glass of the present invention, the compressive stress layer depth determined from the SLP stress profile is preferably 10 μm or more, more preferably 30 μm or more, even more preferably 50 μm or more, and particularly preferably 100 μm or more. The compressive stress layer depth determined from the SLP stress profile is often 300 μm or less, and preferably 200 μm or less. Furthermore, the compressive stress layer depth determined from the SLP stress profile (measured using a scattered light photoelastic stress meter) is preferably 0.10 times or more the thickness of the chemically strengthened crystallized glass. That is, when the thickness of the chemically strengthened crystallized glass is t (unit: μm), the compressive stress layer depth is preferably 0.10t or more. The compressive stress layer depth is more preferably 0.12t or more, even more preferably 0.15t or more, and even more preferably 0.17t or more. The compressive stress layer depth is often 0.25t or less. The thickness of the chemically strengthened crystallized glass is often 0.03 mm or more, preferably 0.1 mm or more, preferably 0.2 mm or more, more preferably 0.3 mm or more, and even more preferably 0.4 mm or more. Furthermore, the thickness of the chemically strengthened crystallized glass is preferably 5.0 mm or less, more preferably 3.0 mm, even more preferably 1.0 mm or less, and most preferably 0.6 mm or less.

[0036] The compressive stress values ​​at each depth can be obtained from the above SLP stress profile. For example, the compressive stress value CS at a depth of 50 μm ５０ The compressive stress value CS is preferably -15 MPa or higher, more preferably -10 MPa or higher, may be 0 MPa or higher, or 15 MPa or higher. ５０ The compressive stress value CS at a depth of 70 μm is often 300 MPa or less, and preferably 200 MPa or less. ７０ The compressive stress value CS is preferably -20 MPa or higher, more preferably -15 MPa or higher, may be 0 MPa or higher, or 10 MPa or higher. ７０ The compressive stress value CS at a depth of 90 μm is often 200 MPa or less, and preferably 100 MPa or less. ９０ The compressive stress value CS is preferably -20 MPa or higher, more preferably -10 MPa or higher, may be 0 MPa or higher, or 5 MPa or higher. ５０ The pressure is often 150 MPa or less, and preferably 100 MPa or less.

[0037] Furthermore, while compressive stress typically acts on the surface of chemically strengthened crystallized glass, tensile stress acts within the interior of the chemically strengthened crystallized glass to balance the compressive stress. The maximum value of tensile stress (CT) in the chemically strengthened crystallized glass of the present invention Ｍａｘ The absolute value of ) is preferably 50 MPa or less, more preferably 45 MPa or less, and may also be 40 MPa or less, in that the fragments are less likely to scatter when the glass is broken. Ｍａｘ There is no particular lower limit to the absolute value of , but it is often 5 MPa or higher. Ｍａｘ This is determined from the SLP stress profile and typically acts at the center of the plate thickness.

[0038] Furthermore, the average value of the tensile stress (CT) of the chemically strengthened crystallized glass of the present invention. ａｖｅ The absolute value of ) is preferably 50 MPa or less, more preferably 40 MPa or less, even more preferably 32 MPa or less, and may also be 28 MPa or less, in that the fragments are less likely to scatter when the glass is broken. ａｖｅThere is no particular lower limit to the absolute value of the stress, but it is often 5 MPa or higher. The average value of the tensile stress is obtained by dividing the integral value of the tensile stress in the thickness direction of the plate in the depth region showing tensile stress in the SLP stress profile by the length of the tensile stress region.

[0039] [Mechanical Properties] The Young's modulus of the chemically strengthened crystallized glass of the present invention is preferably 90 GPa or higher, more preferably 100 GPa or higher, and even more preferably 105 GPa or higher. The above Young's modulus is often 150 GPa or lower. The method for measuring the Young's modulus of the chemically strengthened crystallized glass is as described in the examples below.

[0040] Fracture toughness value K of the chemically strengthened crystallized glass of the present invention ＩＣ This is 1.10 MPa·m １／２ The above is preferable, and 1.20 MPa·m １／２ The above is more preferable, specifically 1.30 MPa·m １／２ The above is even more preferable. The fracture toughness value K ＩＣ The pressure is 2.00 MPa·m １／２ The following is often the case: Fracture toughness value K ＩＣ The measurement method is as described above.

[0041] [Composition] The composition of the chemically strengthened crystallized glass of the present invention at the center of the plate thickness is SiO2, expressed as a mole percentage based on oxides. ２ 60.0-75.0%, Al ２ O ３ 2.0-6.0%, P ２ O ５ Li ２ 20.0-30.0% O, Na ２ O at 0.0-5.0%, K ２ O 0.0-1.0%, MgO 0.0-2.0%, CaO 0.0-2.0%, SrO 0.0-1.0%, ZrO ２ 1.0-5.0%, SnO ２ It contains 0.0 to 1.0% of Y ２ O ３It is preferable that it substantially does not contain [the specified element]. The preferred configuration of the composition at the center of the thickness of the chemically strengthened crystallized glass is the same as the preferred configuration of the chemically strengthened crystallized glass used in the method for manufacturing chemically strengthened crystallized glass, which will be described in detail later.

[0042] <Method for Manufacturing Chemically Strengthened Crystallized Glass> The method for manufacturing chemically strengthened crystallized glass of the present invention involves obtaining a Raman spectrum by Raman spectroscopy, where the region is 380 to 440 cm⁻¹. －１ Let A1 be the peak area, and the range be 520-570 cm². －１ When the peak area is taken as A2, the maximum value of A2 / A1 in the range from the surface to a depth of 0 to 3 μm is 2.2 or less, and Li ２ Si ２ O ５ Chemically strengthened crystallized glass containing crystals is brought into contact with either molten salt A or molten salt B below to perform chemical strengthening and obtain chemically strengthened crystallized glass. Molten salt A: A molten salt containing 30% by mass or more of K salt, 30% by mass or more of Na salt, and 0.02% by mass or more of Li salt. Molten salt B: A molten salt containing 95% by mass or more of K salt. According to the above method for producing chemically strengthened crystallized glass of the present invention, the above chemically strengthened crystallized glass of the present invention can be obtained. The method for producing chemically strengthened crystallized glass of the present invention will be described below.

[0043] [Chemically Strengthened Crystallized Glass] The chemically strengthened crystallized glass used in the production of the chemically strengthened crystallized glass of the present invention has a maximum A2 / A1 value of 2.2 or less in the range of 0 to 3 μm from the surface, and Li ２ Si ２ O ５ Contains crystals. The method of Raman spectroscopy measurement and the method of calculating A2 / A1 above are the same as those for the chemically strengthened crystallized glass of the present invention described above, so the explanation is omitted. Furthermore, preferred embodiments of the chemically strengthened crystallized glass are the same as those for the chemically strengthened crystallized glass of the present invention described above. Furthermore, Li contained in the chemically strengthened crystallized glass ２ Si ２ O ５ Crystal structure, and Li which may be included ２ Si ２ O ５Other crystalline forms are the same as those of the chemically strengthened crystallized glass of the present invention, so their explanation will be omitted.

[0044] The following describes the composition of chemically strengthened crystallized glass. As mentioned above, the composition of chemically strengthened crystallized glass will also be referred to as the "matrix glass composition" below.

[0045] The preferred composition of the chemically strengthened crystallized glass of the present invention (matrix glass composition) is SiO2, expressed as a molar percentage based on oxides. ２ 60.0-75.0%, Al ２ O ３ 2.0-6.0%, P ２ O ５ Li ２ 20.0-30.0% O, Na ２ O at 0.0-5.0%, K ２ O 0.0-1.0%, MgO 0.0-2.0%, CaO 0.0-2.0%, SrO 0.0-1.0%, ZrO ２ 1.0-5.0%, SnO ２ It contains 0.0 to 1.0% of Y ２ O ３ It substantially does not contain. The following describes each component included in the mother glass composition. The following describes each component included in the mother glass composition. Note that, for example, SiO ２ The content expressed as a mole percentage based on oxides is "[SiO ２ It may be written as ]"

[0046] SiO ２ It is a component that makes up the network of glass. It is also a component that increases chemical durability and reduces the occurrence of cracks when the glass surface is scratched.

[0047] SiO ２ The content of is more preferably 61.0% or more, and even more preferably 62.0% or more, in order to improve chemical durability. On the other hand, from the viewpoint of improving meltableness, SiO ２ The content of is more preferably 72.0% or less, and even more preferably 70.0% or less.

[0048] Al ２ O ３ It is a component that improves ion exchange performance during chemical strengthening and increases surface compressive stress after chemical strengthening. Also, crystals containing Al and Li (for example, Li ２ Si ２ O ５ It contributes to the formation of crystals. From the viewpoint of obtaining the above effect, Al ２ O ３ A content of 2.2% or more is more preferable. On the other hand, it is sometimes required that crystal growth is less likely to occur during melting, that devitrification defects are less likely to occur and that the yield tends to be higher, and that the high-temperature viscosity of the glass is reduced to make it easier to melt. From this viewpoint, Al ２ O ３ The content of is more preferably 5.0% or less, and even more preferably 4.5% or less, 4.0% or less, 3.5% or less, and 3.0% or less, in that order.

[0049] SiO ２ and Al ２ O ３ These are all components that stabilize the structure of glass. To reduce brittleness, SiO ２ and Al ２ O ３ The total content is preferably 62.0% or more, more preferably 64.0% or more, and even more preferably 66.0% or more. Also, SiO ２ and Al ２ O ３ Both tend to increase the melting temperature of the glass. Therefore, in order to make it easier to melt, SiO ２ and Al ２ O ３ The total content is preferably 90.0% or less, more preferably 80.0% or less, and even more preferably 75.0% or less.

[0050] Li ２ O is a component that can undergo ion exchange and improves the meltability of glass. Also, within the above range, Li ２ The presence of O makes it easier to obtain crystallized glass when heat treatment is applied. From the above viewpoint, Li ２The O content is more preferably 21.0% or more, even more preferably 22.0%, particularly preferably 24.0% or more, and most preferably 25.0% or more.

[0051] On the other hand, in order to reduce the crystal growth rate during glass molding and to minimize quality degradation due to devitrification, Li ２ The O content is more preferably 29.0% or less, even more preferably 28.0% or less, and particularly preferably 27.0% or less.

[0052] As mentioned above, the chemically strengthened crystallized glass is Li ２ Si ２ O ５ Contains crystals. The type of crystals precipitated on the glass depends on the composition of the glass. That is, the type and number of crystals that precipitate can be adjusted by the range of the glass composition (preferably the composition of the mother glass). Li ２ Si ２ O ５ The matrix glass composition on which crystals can precipitate is SiO ２ 60.0-70.0%, Al ２ O ３ 2.0 to 4.0%, Li ２ Compositions containing 20.0-30.0% oxygen are examples.

[0053] Na ２ O and K ２ O is a component that improves the meltability of glass and reduces the crystal growth rate during glass molding. It is also preferable to include a small amount to improve ion exchange performance.

[0054] Na ２ O is a component that can undergo ion exchange in chemical strengthening treatment using potassium salts, and also a component that reduces the viscosity of glass. ２ Including O makes it easier to adjust the above A2 / A1 range to the above range. To obtain the above effect, Na ２The O content is preferably 0.3% or more, and more preferably 0.5% or more, 0.8% or more, 1.2% or more, 1.6% or more, and 2.0% or more, in that order. On the other hand, from the viewpoint of maintaining the glass network and avoiding a decrease in surface compressive stress (Na_CS) during the strengthening treatment with sodium salt, Na ２ The O content is more preferably 4.0% or less, even more preferably 3.5% or less, and particularly preferably 3.0% or less.

[0055] K ２ O is a component that suppresses devitrification by inhibiting the rise in devitrification temperature, and also improves ion exchange performance. ２ The O content is more preferably 0.05% or more, even more preferably 0.1% or more, and particularly preferably 0.15% or more. On the other hand, from the viewpoint of avoiding a decrease in surface compressive stress (K_CS) during the strengthening treatment with sodium salt, K ２ The O content is preferably 0.9% or less, more preferably 0.8% or less, and even more preferably 0.7% or less. ２ O does not necessarily need to be included.

[0056] Li ２ O content, Na ２ O content and K ２ The total oxygen content, R, is preferably 21.0 to 35.0%, more preferably 25.0 to 32.0%, and particularly preferably 27.0 to 31.0%, from the viewpoint of suppressing the rise in devitrification temperature and reducing the crystal growth rate.

[0057] Li for the above R ２ Ratio of O content ([Li ２ O] / ([Li ２ O] + [Na] ２ O] + [K ２ O]), hereinafter referred to as “Li ２ O / R ２ Li (also written as "O") is more preferably 0.80 or higher, and even more preferably 0.85 or higher, from the viewpoint of further improving the deep stress in the chemical strengthening properties. ２ O / R ２From the viewpoint of further improving chemical resistance, O is more preferably 0.99 or less, even more preferably 0.98 or less, and particularly preferably 0.95 or less.

[0058] Na for the above ２ Ratio of O content ([Na ２ O] / ([Li ２ O] + [Na] ２ O] + [K ２ O]), hereinafter referred to as “Na ２ O / R ２ Na (also written as "O") is preferably greater than 0.00, more preferably 0.01 or higher, even more preferably 0.02 or higher, particularly preferably 0.05 or higher, and most preferably 0.06 or higher, from the viewpoint of further improving the deep stress in chemical strengthening properties. ２ O / R ２ From the viewpoint of further improving resistance to chemicals, O is preferably 0.40 or less, more preferably 0.30 or less, even more preferably 0.20 or less, and particularly preferably 0.10 or less.

[0059] K for the above R ２ Ratio of O content ([K ２ O] / ([Li ２ O] + [Na] ２ O] + [K ２ O]), hereinafter referred to as “K ２ O / R ２ (Also written as "O") From the viewpoint of further increasing the electrical resistance of the glass, a value of 0.001 or higher is preferred, 0.004 or higher is more preferred, and 0.01 or higher is even more preferred. ２ O / R ２ From the viewpoint of increasing the compressive stress near the surface in the chemical strengthening properties, O is preferably 0.40 or less, more preferably 0.30 or less, even more preferably 0.20 or less, and particularly preferably 0.10 or less. ２ O / R ２ O may be 0.

[0060] Also, Li ２ O / R ２ O and Na ２ O / R ２ O and K ２ O / R ２The product with O is preferably 0.00005 or higher, more preferably 0.0001 or higher, and even more preferably 0.001 or higher, from the viewpoint of suppressing the rise in devitrification temperature and reducing the crystal growth rate. Furthermore, the above product is more preferably 0.020 or lower. Note that the above product may also be 0.

[0061] Also, Na ２ K in relation to O content ２ Ratio of O content ([K ２ O] / [Na ２ O], hereinafter referred to as “K ２ O / Na ２ The value of (also written as "O") is preferably 0.50 or less, more preferably 0.40 or less, and even more preferably 0.30 or less, as it makes it easier to adjust the maximum value of A2 / A1 within the above range. ２ O / Na ２ O is often 0.02 or higher, and preferably 0.05 or higher.

[0062] Al for the above R ２ O ３ Ratio of content ([Al ２ O ３ ] / ([Li ２ O] + [Na] ２ O] + [K ２ O]), hereinafter referred to as “Al ２ O ３ / R ２ Al (also written as "O") is preferably 0.02 or higher, more preferably 0.04 or higher, even more preferably 0.06 or higher, and particularly preferably 0.07 or higher. ２ O ３ / R ２ O is preferably 1.00 or less, more preferably 0.50 or less, even more preferably 0.20 or less, and particularly preferably 0.15 or less.

[0063] [Al ２ O ３ ]-[Na ２ O] - [K ２ O] + [Li ２ The value represented by [O] is preferably 15.0% or more, and more preferably 20.0% or more. Furthermore, the above value is preferably 35.0% or less, and more preferably 30.0% or less.

[0064] MgO may be included to reduce viscosity during dissolution, etc. The MgO content is more preferably 0.05% or more, and even more preferably 0.08% or more. On the other hand, in order to easily increase the compressive stress layer during chemical strengthening treatment, the MgO content is more preferably 1.5% or less, and even more preferably 1.0% or less, and 0.5% or less, in that order. MgO may be substantially absent.

[0065] CaO is a component that improves the meltability of the glass and may be included. The CaO content is more preferably 0.005% or more, and even more preferably 0.01% or more. On the other hand, in terms of easily increasing the compressive stress value during chemical strengthening treatment, the CaO content is more preferably 1.8% or less, even more preferably 1.0% or less, particularly preferably 0.8% or less, and most preferably 0.5% or less. CaO may be substantially omitted.

[0066] To enhance the stability of the glass, it is more preferable to include at least one of MgO and CaO, and even more preferable to include MgO. The total content of MgO and CaO is preferably 0.01% or more, more preferably more than 0.05%, even more preferably 0.1% or more, and particularly preferably 0.2% or more. In terms of further improving the chemical strengthening properties, the total content of MgO and CaO is preferably 3.5% or less, and more preferably 3.0% or less, 2.0% or less, and 1.0% or less, in that order. Note that MgO and CaO may be substantially absent.

[0067] SrO is a component that improves the meltability of the glass and may be included. The SrO content is more preferably 0.1% or more, even more preferably 0.15% or more, and particularly preferably 0.5% or more. In terms of making it easier to increase the compressive stress value during chemical strengthening treatment, the SrO content is more preferably 1.8% or less, even more preferably 1.5% or less, particularly preferably 1.0% or less, and most preferably 0.5% or less. SrO may be substantially absent.

[0068] BaO is a component that improves the meltability of the glass and may be included. When BaO is included, the content is preferably 0.1% or more, more preferably 0.15% or more, and even more preferably 0.5% or more. In terms of making it easier to increase the compressive stress value during chemical strengthening treatment, the BaO content is preferably 2.0% or less, more preferably 1.5% or less, even more preferably 1.0% or less, and particularly preferably 0.5% or less. BaO may be substantially omitted.

[0069] ZnO is a component that improves the meltability of glass. The ZnO content is preferably 0.1% or more, more preferably 0.15% or more, and even more preferably 0.5% or more. In terms of making it easier to increase the compressive stress value during chemical strengthening treatment, the ZnO content is preferably 3.0% or less, more preferably 2.0% or less, even more preferably 1.0% or less, and particularly preferably 0.5% or less. ZnO may be substantially absent.

[0070] TiO ２ TiO is a component that is highly effective in suppressing glass solarization and is a material that forms crystal nuclei, so it may be included. ２ When containing, the content is preferably 0.03% or more, more preferably 0.05% or more, and even more preferably 0.08% or more. On the other hand, TiO ２ Because it has light-absorbing properties, TiO ２ The content is preferably 2.5% or less, more preferably 2.0% or less, even more preferably 1.5% or less, and particularly preferably 1.0% or less. ２ It does not necessarily have to be included in practice.

[0071] ZrO ２ ZrO is a component that makes it easier to increase the surface compressive stress of chemically strengthened crystallized glass. Also, because it is a material that forms crystal nuclei, ２ It may contain ZrO ２The content of is more preferably 1.2% or more, and even more preferably 1.5% or more, and 1.7% or more, in that order. ZrO ２ The content of is more preferably 4.0% or less, and even more preferably 3.0% or less, 2.5% or less, and 2.3% or less, in that order.

[0072] In the composition of the mother glass, Y ２ O ３ It is preferable that it is substantially not included. ２ O ３ The content is preferably less than 0.1%, more preferably 0.08 mol% or less, and even more preferably 0.05 mol% or less.

[0073] P ２ O ５ This makes it easier to increase the compressive stress layer during chemical strengthening. Also, Li ２ Si ２ O ５ In some cases, crystal nuclei, which are the structures that cause crystal precipitation, may be more easily precipitated. ２ O ５ The content of is more preferably 0.2% or more, and even more preferably 0.5% or more, 0.8% or more, 1.0% or more, and 1.2% or more, in that order. On the other hand, from the viewpoint of increasing acid resistance, P ２ O ５ The content of is more preferably 2.5% or less, and even more preferably 2.0% or less.

[0074] B ２ O ３ This reduces the brittleness of the glass and improves its crack resistance, or improves its meltability. ２ O ３ The content is preferably 0.5% or more, more preferably 1.0% or more, and even more preferably 2.0% or more. On the other hand, in terms of maintaining good acid resistance, B ２ O ３ The content of is preferably 8.0% or less. ２ O ３ The content is more preferably 6.0% or less, even more preferably 4.0% or less, and particularly preferably 2.0% or less. From the viewpoint of preventing striation formation during melting, it is also preferable that it be substantially absent.

[0075] La ２ O ３ This component increases the surface compressive stress of chemically strengthened crystallized glass while simultaneously reducing the crystal growth rate. ２ O ３ The amount 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 the chemical strengthening treatment, so La ２ O ３ The amount 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. ２ O ３ It is also preferable that it is not included in any meaningful sense.

[0076] Nb ２ O ５、 Ta ２ O ５ , Gd ２ O ３ , CEO ２ These components have the effect of suppressing glass solarization and improving meltability, and may be included. When these components are included, the content of each is preferably 0.03% or more, more preferably 0.1% or more, even more preferably 0.5% or more, particularly preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, it is preferably 3.0% or less, more preferably 2.0% or less, and even more preferably 1.0% or less.

[0077] Fe ２ O ３ Since it absorbs heat rays, it has the effect of improving the solubility of glass, and it is preferable to include it when mass-producing glass using a large melting furnace. In that 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, expressed in mass percent based on oxide. On the other hand, Fe ２ O ３Since excessive amounts of this substance cause discoloration, 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, in terms of mass percentage based on oxides, from the viewpoint of improving the transparency of the glass.

[0078] Furthermore, other coloring components may be added, to the extent that they do not hinder the achievement of desired chemical strengthening properties, etc. Examples of other coloring components include Co ３ O ４ MnO ２ , NiO, CuO, Cr ２ O ３ , V ２ O ５ , Bi ２ O ３ SeO ２ Er ２ O ３ , Nd ２ O ３ These are some examples of suitable options.

[0079] SO4 is used as a clarifying agent when melting glass. ３ It may also contain chlorides, fluorides, etc., as appropriate. ２ O ３ It is preferable that it does not contain Sb. ２ O ３ If it is present, it is preferably 0.3% or less, more preferably 0.1% or less, and most preferably not present. From the viewpoint of clarifying bubbles in the glass, SnO ２ The content of is more preferably 0.05% or more, and even more preferably 0.08% or more. Also, SnO ２ The content of is preferably 1.5% or less, more preferably 1.2% or less, even more preferably 0.5% or less, particularly preferably 0.4% or less, and most preferably 0.2% or less, in order to suppress the occurrence of defects.

[0080] The glass having the above-described matrix glass composition preferably has a devitrification temperature of 1300°C or lower. A devitrification temperature of 1280°C or lower is more preferable, and 1250°C or lower is even more preferable. Particularly preferable are, in order, 1240°C or lower, 1230°C or lower, 1220°C or lower, and 1210°C or lower. The lower limit of the devitrification temperature is not particularly limited, but is usually 1100°C or higher.

[0081] By setting the devitrification temperature to 1300°C or lower (preferably 1250°C or lower), glass can be stably molded, improving manufacturing characteristics. Specifically, for example, when molding glass by the float process, if crystals form before the molten glass is poured into the float bath, the crystals may erode the bricks that make up the float bath. By setting the devitrification temperature to 1300°C or lower (preferably 1250°C or lower), the erosion of the bricks can be suppressed. The devitrification temperature of glass is defined as the minimum temperature at which no crystals precipitate on the surface or inside the glass when crushed glass particles of 2 mm to 3 mm are placed in a platinum dish, heat-treated for 17 hours in an electric furnace controlled to a constant temperature, and observed with an optical microscope after heat treatment.

[0082] In this specification, the glass transition temperature Tg and the crystallization peak temperature Tc can be measured by a differential scanning calorimetry (DSC). In this specification, a Bruker DSC3300SA is used as the DSC. The DSC measurement procedure is as follows: First, the glass is crushed and classified into 150-300 μm particles to obtain glass powder. The obtained glass powder is placed in a platinum pan (container) and heated from room temperature to 1050°C for DSC measurement. The heating rate is 5°C / min.

[0083] The curve obtained by DSC (DSC curve) has temperature on the horizontal axis and heat quantity on the vertical axis. By analyzing the DSC curve, the glass transition temperature Tg and the crystallization peak temperature Tc can be obtained. When a glass transition occurs in a sample, a baseline shift is observed in the DSC curve. In this specification, the extrapolation glass transition onset temperature is defined as the glass transition temperature Tg. The extrapolation glass transition onset temperature is defined as the temperature at the intersection of a straight line extending from the low-temperature baseline to the high-temperature side and a tangent line drawn at the point where the slope of the curve representing the stepwise change portion of the glass transition is maximum.

[0084] Furthermore, if crystallization occurs in the sample, an exothermic peak is observed in the DSC curve. In this specification, the temperature at which the exothermic peak reaches its maximum value is defined as the crystallization peak temperature. Note that the glass of the mother glass composition may have multiple crystallization peak temperatures.

[0085] The glass transition temperature Tg is preferably 400°C or higher, more preferably 430°C or higher, and even more preferably 450°C or higher. Furthermore, the glass transition temperature Tg is preferably 570°C or lower, more preferably 540°C or lower, and even more preferably 520°C or lower.

[0086] In a glass with a matrix glass composition, the highest crystallization peak temperature Tc is preferably 700°C or higher, more preferably 730°C or higher, and even more preferably 750°C or higher. Furthermore, the highest crystallization peak temperature Tc is preferably 870°C or lower, more preferably 840°C or lower, and even more preferably 820°C or lower. In addition, in a glass with a matrix glass composition, if there are multiple crystallization peak temperatures Tc, the lowest crystallization peak temperature Tc is preferably 520°C or higher, more preferably 550°C or higher, and even more preferably 570°C or higher. Furthermore, the lowest crystallization peak temperature Tc is preferably 680°C or lower, more preferably 650°C or lower, and even more preferably 630°C or lower.

[0087] Furthermore, the "β-OH value" was measured by the FT-IR method at a reference wavelength of 4000 cm². －１ Transmittance X １ (%), the absorption wavelength of the hydroxyl group is 3570 cm. －１ Minimum transmittance X in the vicinity ２The β-OH value can be calculated from the percentage (%) and the thickness t of the glass plate (in mm) using formula (1). β-OH value = (1 / t) log １０ (X １ / X ２ )・・・・・(1) The β-OH value can be adjusted by the amount of water contained in the glass raw material and the dissolution conditions.

[0088] The crystallized glass for chemical strengthening, with a mother glass composition, has a β-OH value of 0.1 mm. －１ Preferably, it should be 0.15 mm or more. －１ The above is more preferable, 0.2 mm －１ The above is even more preferable, 0.22 mm －１ The above is particularly preferred, 0.25 mm －１ The above is the most preferable option.

[0089] Here, chemically strengthened crystallized glass can be manufactured by conventional methods. For example, crystallized glass is obtained, and then subjected to a predetermined heat treatment to obtain chemically strengthened crystallized glass. More specifically, the raw materials for each component of the glass are mixed and heated and melted in a glass melting furnace. After that, the glass is homogenized by a known method, formed into a desired shape such as a glass plate, and slowly cooled.

[0090] 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.

[0091] Subsequently, the molded glass is ground and polished as needed to form a glass substrate. When cutting or chamfering the glass substrate to a predetermined shape and size, it is preferable to do so before applying the chemical strengthening treatment described later, as this will allow a compressive stress layer to be formed on the edges during the subsequent chemical strengthening treatment.

[0092] The heat treatment is not particularly limited, but for example, it is carried out by holding the obtained glass substrate at a temperature below the crystallization peak temperature. For example, a chemically strengthened crystallized glass can be obtained by heat treatment in which the substrate is held at 450 to 600°C for 1 to 6 hours and then at 600 to 800°C for 0.5 to 6 hours. The above heat treatment may be carried out in three stages. For example, a chemically strengthened crystallized glass can be obtained by holding the substrate at 450 to 550°C for 1 to 6 hours, then at 500 to 600°C for 0.5 to 6 hours, and then at 600 to 800°C for 0.5 to 6 hours.

[0093] The Young's modulus of the chemically strengthened crystallized glass is preferably 90 GPa or higher, more preferably 100 GPa or higher, and even more preferably 105 GPa or higher. The above Young's modulus is often 150 GPa or lower. The method for measuring the Young's modulus of the chemically strengthened crystallized glass follows the method described in the examples below.

[0094] Fracture toughness value K of chemically strengthened crystallized glass ＩＣ This is 1.10 MPa·m １／２ The above is preferable, and 1.20 MPa·m １／２ The above is more preferable, specifically 1.30 MPa·m １／２ The above is even more preferable. The fracture toughness value K ＩＣ The pressure is 2.00 MPa·m １／２ The following is often the case: Fracture toughness value K ＩＣ The measurement method is as described above.

[0095] [Chemical Strengthening Treatment] In the method for producing chemically strengthened crystallized glass of the present invention, chemical strengthening is performed by contacting the crystallized glass for chemical strengthening with the following molten salt A or molten salt B to obtain chemically strengthened crystallized glass. Molten salt A: A molten salt containing 30% by mass or more of K salt, 30% by mass or more of Na salt, and 0.02% by mass or more of Li salt. Molten salt B: A molten salt containing 95% by mass or more of K salt. Hereinafter, the treatment of chemically strengthening the crystallized glass for chemical strengthening by contacting it with molten salt A or molten salt B is also referred to as the "chemical strengthening treatment". When chemical strengthening is performed, metal ions with small ionic radii (typically Na ions or Li ions) in the crystallized glass for chemical strengthening are replaced by metal ions with large ionic radii (typically K ions for Na ions, and Na ions or K ions for Li ions). The above K salt, Na salt, and Li salt refer to salts containing K ions, Na ions, and Li ions as cationic components, respectively.

[0096] The method for contacting the chemically strengthened crystallized glass with molten salt A or molten salt B is not particularly limited, but for example, it can be carried out by immersing the chemically strengthened crystallized glass in molten salt A or molten salt B. The chemical strengthening treatment can be carried out, for example, by immersing the chemically strengthened crystallized glass in molten salt A or molten salt B heated to 350 to 600°C for 0.1 to 500 hours.

[0097] When chemical strengthening treatment is performed using molten salt A, the temperature of molten salt A is preferably 350°C or higher, more preferably 400°C or higher, even more preferably 420°C or higher, and particularly preferably 430°C or higher. Furthermore, the temperature of molten salt A is preferably 550°C or lower, more preferably 500°C or lower, and even more preferably 470°C or lower. When chemical strengthening treatment is performed using molten salt A, the contact time (chemical strengthening time) between the chemically strengthened crystallized glass and molten salt A is preferably 0.3 hours or more, more preferably 0.5 hours or more, even more preferably 1 hour or more, and particularly preferably 2 hours or more. Furthermore, the above chemical strengthening time is preferably 200 hours or less, more preferably 100 hours or less, even more preferably 30 hours or less, and particularly preferably 10 hours or less. It is also preferable that the temperature of molten salt A is 430°C or higher and the chemical strengthening time is 150 minutes or more.

[0098] Furthermore, when performing chemical strengthening treatment using molten salt A, the temperature of molten salt A is set to T Ｋ , chemical strengthening time t Ｋ In this case, it is also preferable that the G value, which can be calculated using the following formula (PI), is between 3.8 and 9.5.

[0099]

[0100] In formula (PI), t is the thickness of the chemically strengthened crystallized glass plate, and the unit of t is m. Ｋ The unit is °C. In formula (PI), t Ｋ The unit is seconds. In formula (PI), E is 125,000 J / mol. In formula (PI), R is 8.31 J / (K·mol).

[0101] Furthermore, when chemical strengthening treatment is performed using molten salt B, the temperature of molten salt B is preferably 350°C or higher, more preferably 400°C or higher, even more preferably 420°C or higher, and particularly preferably 430°C or higher. Also, the temperature of molten salt B is preferably 550°C or lower, more preferably 500°C or lower, and even more preferably 470°C or lower. When chemical strengthening treatment is performed using molten salt B, the contact time (chemical strengthening time) between the chemically strengthened crystallized glass and molten salt B is preferably 0.5 hours or more, more preferably 1 hour or more, even more preferably 2 hours or more, and particularly preferably 4 hours or more. Furthermore, the above chemical strengthening time is also preferably 200 minutes or more, more preferably 250 minutes or more, and may be 5 hours or more. Furthermore, the above chemical strengthening time is also preferably 200 hours or less, more preferably 100 hours or less, even more preferably 30 hours or less, and particularly preferably 10 hours or less. It is also preferable that the temperature of molten salt B is 430°C or higher and the chemical strengthening time is 200 minutes or more. It is also preferable that the temperature of molten salt B is 430°C or higher and the chemical strengthening time is 250 minutes or longer.

[0102] Furthermore, when performing chemical strengthening treatment using molten salt B, the temperature of molten salt B is set to T Ｋ , chemical strengthening time t Ｋ In this case, it is also preferable that the G value, which can be calculated using the following formula (PI), be between 4.5 and 10.0.

[0103]

[0104] In formula (PI), t is the thickness of the chemically strengthened crystallized glass plate, and the unit of t is m. Ｋ The unit is °C. In formula (PI), t Ｋ The unit is seconds. In formula (PI), E is 125,000 J / mol. In formula (PI), R is 8.31 J / (K·mol).

[0105] The above molten salt A is not particularly limited as long as it contains 30% by mass or more of K salt, 30% by mass or more of Na salt, and 0.02% by mass or more of Li salt. The content of K salt in molten salt A is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more, based on the total mass of molten salt A. The content of K salt in molten salt A is preferably 69% by mass or less, and more preferably 65% ​​by mass or less, based on the total mass of molten salt A. The content of Na salt in molten salt A is preferably 33% by mass or more, more preferably 35% by mass or more, and even more preferably 37% by mass or more, based on the total mass of molten salt A. The content of Na salt in molten salt A is preferably 69% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, and especially preferably 45% by mass or less, based on the total mass of molten salt A. The content of Li salt in molten salt A is preferably 0.03% by mass or more, based on the total mass of molten salt A. The Li salt content in molten salt A is preferably 1% by mass or less, more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0.05% by mass or less, relative to the total mass of molten salt A.

[0106] The above K salt is potassium nitrate (KNO). ３ ), potassium sulfate (K ２ SO ４ ), and potassium carbonate (K ２ CO ３ ) are examples, and the above K salt is KNO ３ It is preferable that the above Na salt is sodium nitrate (NaNO ３ ), sodium sulfate (Na ２ SO ４), and sodium carbonate (Na ２ CO ３ ) are examples, and the above Na salt is NaNO ３ It is preferable that the above Li salt is lithium nitrate (LiNO3). ３ ), lithium sulfate (Li ２ SO ４ ), and lithium carbonate (Li ２ CO ３ ) are examples, and the above Li salt is LiNO ３ It is preferable that this be the case.

[0107] KNO in molten salt A ３ The content of is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more, relative to the total mass of molten salt A. ３ The content of is preferably 69% by mass or less, and more preferably 65% ​​by mass or less, relative to the total mass of molten salt A. ３ The content of is preferably 33% by mass or more, more preferably 35% by mass or more, and even more preferably 37% by mass or more, relative to the total mass of molten salt A. ３ The content of LiNO in molten salt A is preferably 69% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, and particularly preferably 45% by mass or less, relative to the total mass of molten salt A. ３ The content of is preferably 0.03% by mass or more relative to the total mass of molten salt A. ３ The content of is preferably 1% by mass or less, more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0.05% by mass or less, relative to the total mass of molten salt A.

[0108] The molten salt B described above is not particularly limited as long as it contains 95% by mass or more of K salt. The K salt content in the molten salt B is preferably 96% by mass or more, more preferably 97% by mass or more, even more preferably 98% by mass or more, and particularly preferably 99% by mass or more, based on the total mass of the molten salt B. The K salt content in the molten salt B may be 100% by mass or less, based on the total mass of the molten salt B. The K salt described above is potassium nitrate (KNO).３ ), potassium sulfate (K ２ SO ４ ), and potassium carbonate (K ２ CO ３ ) are examples, and the above K salt is KNO ３ It is preferable that this is the case. KNO in molten salt B ３ The content of is preferably 96% by mass or more, more preferably 97% by mass or more, even more preferably 98% by mass or more, and particularly preferably 99% by mass or more, relative to the total mass of molten salt B. ３ The content of this substance may be 100% by mass or less relative to the total mass of molten salt B.

[0109] Molten salts A and B may contain components other than those listed above. Examples of these other components include nitrates, sulfates, carbonates, and chlorides other than those listed above. Examples of nitrates include 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 metal salts may be used individually or in combination.

[0110] Molten salt

[0111] The 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. In particular, it is preferable to perform a single-stage chemical strengthening treatment for two hours or more using molten salt A or molten salt B. Furthermore, when performing multiple chemical strengthening treatments, it is also preferable to perform the treatment using molten salt A or molten salt B for two hours or more as the last of the chemical strengthening treatments.

[0112] Furthermore, the preferred properties of the chemically strengthened crystallized glass obtained by the method for producing chemically strengthened crystallized glass of the present invention are the same as the preferred properties of the chemically strengthened crystallized glass of the present invention described above. For example, the compressive stress layer depth determined from the above SLP stress profile is preferably 10 μm or more, more preferably 30 μm or more, even more preferably 50 μm or more, and particularly preferably 100 μm or more. The compressive stress layer depth determined from the SLP stress profile is often 300 μm or less, and preferably 200 μm or less. It is also preferable that the obtained chemically strengthened crystallized glass does not have a Na ion diffusion layer. Furthermore, in the obtained chemically strengthened crystallized glass, the maximum value of the tensile stress (CT) Ｍａｘ The absolute value of ) is preferably 50 MPa or less, more preferably 45 MPa or less, and may also be 40 MPa or less, in that the fragments are less likely to scatter when the glass is broken. Ｍａｘ There is no particular lower limit to the absolute value of , but it is often 5 MPa or higher. Ｍａｘ This is determined from the SLP stress profile and typically acts at the center of the plate thickness. The measurement method and definition are as described above.

[0113] <Applications> The chemically strengthened crystallized glass of the present invention is useful, for example, as a cover glass. The cover glass can also be suitably used for surface protection of displays and solar cell modules, etc. In particular, the chemically strengthened crystallized glass of the present invention is useful as a cover glass used in mobile devices such as mobile phones, smartphones, personal digital assistants (PDAs), and tablet devices. Furthermore, it is useful as a cover glass for display devices such as televisions (TVs), personal computers (PCs), and touch panels that are not intended to be portable, as well as a cover glass provided on the surface of solar cell modules, building materials such as elevator walls, walls of buildings such as houses and office buildings (full-surface displays), and window glass, and as well as for tabletops, interiors of automobiles and airplanes, etc. It is also useful as a cover glass for the above articles. Furthermore, it can be applied to applications such as casings with curved shapes by bending and bending forming.

[0114] The present invention will be described in more detail below based on the following examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples. Examples 2, 3, 5, and 6 are comparative examples, while Examples 1 and 4 are examples.

[0115] First, we will explain the procedure for obtaining the chemically strengthened crystallized glass shown in Example 1 as a representative example.

[0116] <Example 1> First, glass raw materials were mixed to obtain glass material A, which was then melted in a platinum crucible to obtain the glass composition shown in Table 1 below, in molar percentages based on oxides. More specifically, oxides, hydroxides, carbonates, or nitrates used as glass raw materials were appropriately selected from commonly used glass raw materials and weighed to obtain 1000 g of glass.

[0117] Next, the mixed raw materials were placed in a platinum crucible and melted in a resistance-heated electric furnace at 1500-1700°C for about 3 hours. After degassing and homogenization, molten glass was obtained. The obtained molten glass was poured into a mold, held at a temperature 50°C above the glass transition point for 1 hour, and then 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 to form glass plates. The thickness of the glass plates was 0.6 mm.

[0118] Furthermore, after forming glass material A into a glass plate, it was heat-treated by holding it at 530°C for 2 hours, and then at 740°C for 2 hours. The heat treatment atmosphere was air. Chemically strengthened crystallized glass for chemical strengthening was obtained using the above procedure. In addition, the fracture toughness value (K) was obtained from the above glass block using the method described above. ＩＣ Sample pieces for measuring ( ) and sample pieces for measuring Young's modulus were cut out and subjected to the same heat treatment as described above. The obtained chemically strengthened crystallized glass was subjected to chemical strengthening treatment under the conditions described in Table 2 to obtain the chemically strengthened crystallized glass of Example 2. The molten salt used in Example 1 corresponds to molten salt B described above.

[0119] <Examples 2 to 6> The chemically strengthened crystallized glass used was the glass material shown in Table 2, and the chemical strengthening treatment was carried out under the conditions described in Table 2 to obtain the chemically strengthened crystallized glass of each example. The molten salt used in Example 4 corresponds to molten salt A above. For glass material B used in Examples 5 and 6, heat treatment was performed under the conditions of holding at 540°C for 4 hours, then at 600°C for 4 hours, and then at 780°C for 4 hours.

[0120] <Raman Spectroscopy Measurement> Raman spectroscopy measurements were performed using the method described above, and the parameters listed in Tables 1 and 2 were obtained.

[0121] <Measurement of stress profile> The stress profile of the chemically strengthened crystallized glass was obtained by the method described above.

[0122] <Measurement of Young's Modulus> In the procedure for obtaining each of the above glass materials, the Young's modulus of the chemically strengthened crystallized glass was measured using the cut sample pieces. Specifically, the measurement was performed using the ultrasonic pulse method with the above sample pieces in accordance with JIS R 1602. The Young's modulus of the chemically strengthened crystallized glass corresponds to the Young's modulus at the center of the thickness of the chemically strengthened crystallized glass. Furthermore, the Young's modulus at the in-plane center of the chemically strengthened crystallized glass was measured in the same manner as the measurement of the above sample pieces, and the value was the same as the value measured using the above sample pieces. Therefore, the Young's modulus at the in-plane center is omitted in the table below.

[0123] <Measurement of Fracture Toughness> In the procedure for obtaining each of the glass materials described above, the fracture toughness of the chemically strengthened crystallized glass was measured using the cut sample pieces. The fracture toughness was measured using the DCDC method described above.

[0124] <Humidity Resistance Evaluation> The humidity resistance of each example of chemically strengthened crystallized glass was evaluated according to the following procedure. Specifically, first, each example of chemically strengthened crystallized glass was cut into 5 cm squares to serve as test samples. The obtained test samples were placed in a constant temperature and humidity chamber (SH-642, manufactured by ESPEC Corporation) and left to stand for two weeks in an environment of 25°C and 60% relative humidity. After each test sample had stood, the surface of each test sample was observed visually. The observation was performed in an environment with direct illumination from a high-intensity light source at an illuminance of 25,000 lx, and the observation distance was 20 cm. Based on the observation results, the humidity resistance of the chemically strengthened crystallized glass was evaluated according to the following criteria. A rating is preferable for practical purposes. ・A: No foreign matter was observed. ・B: Foreign matter was observed. The foreign matter appeared as white dots, with a diameter of approximately 0.5 mm.

[0125] <Results> The composition of the chemically strengthened crystallized glass for each example is shown in Table 1. Table 1 also shows the Young's modulus and fracture toughness values ​​of the chemically strengthened crystallized glass. Furthermore, the chemical strengthening treatment conditions, the above measurement results, and the above evaluation results for the chemically strengthened crystallized glass for each example are shown in Table 2. The meaning of each symbol in Tables 1 and 2 is as described above. In Table 2, "450-520 cm" －１ The "number of peaks in" refers to the number of peaks in the above wavenumber range of the obtained Raman spectrum, as described above. Ｂ This counts the number of peaks showing a scattering intensity of more than three times that of the above. (1000-1080 cm) －１ The same applies to "the number of peaks in [location]".

[0126]

[0127]

[0128] From the results shown in Table 2, A2 / A1 is 2.2 or less in the range of 0 to 3 μm from the surface, and Li ２ Si ２ O ５ When crystals are present, it has been confirmed to have excellent moisture resistance.

[0129] Furthermore, the entire contents of the specifications, claims, drawings, and abstracts of Japanese Patent Application No. 2024-227177, filed on December 24, 2024, and Japanese Patent Application No. 2025-046956, filed on March 21, 2025, are incorporated herein by reference as disclosures of the present invention.

Claims

1. In the Raman spectrum obtained by Raman spectroscopy, 380–440 cm⁻¹ －１ Let A1 be the peak area, and the range be 520-570 cm². －１ When the peak area is denoted as A2, the maximum value of A2 / A1 in the range from the surface to a depth of 0 to 3 μm is 2.2 or less, and Li ２ Si ２ O ５ Chemically strengthened crystallized glass containing crystals.

2. Let the A2 / A1 at a depth of 1 μm from the surface be R １μｍ and let the A2 / A1 at a depth of 10 μm from the surface be R １０μｍ . When R １μｍ / R １０μｍ is 0.7 to 1.3, the chemically strengthened crystallized glass according to claim 1.

3. The chemically strengthened crystallized glass according to claim 1 or 2, wherein the Young's modulus is 10⁵ GPa or higher.

4. Fracture toughness value K ＩＣ However, 1.30 MPa·m １／２ The chemically strengthened crystallized glass according to claim 1 or 2.

5. The chemically strengthened crystallized glass according to claim 1 or 2, wherein the compressive stress layer depth measured using a scattered light photoelastic stress meter is 30 μm or more.

6. A chemically strengthened crystallized glass according to claim 1 or 2, which does not have a Na ion diffusion layer.

7. The chemically strengthened crystallized glass according to claim 1 or 2, wherein the absolute value of the tensile stress at the center of the plate thickness is 50 MPa or less.

8. The composition at the center of the plate thickness is SiO₂, expressed as a mole percentage based on oxides. ２ 60.0-75.0%, Al ２ O ３ 2.0-6.0%, P ２ O ５ Li ２ 20.0-30.0% O, Na ２ O at 0.0-5.0%, K ２ O 0.0-1.0%, MgO 0.0-2.0%, CaO 0.0-2.0%, SrO 0.0-1.0%, ZrO ２ 1.0-5.0%, SnO ２ It contains 0.0 to 1.0% of Y ２ O ３ A chemically strengthened crystallized glass according to claim 1 or 2, which substantially does not contain the specified element.

9. The chemically strengthened crystallized glass according to claim 1 or 2, wherein the K ion diffusion depth is 7 μm or more from the surface.

10. In the Raman spectrum obtained by Raman spectroscopy, 380–440 cm⁻¹ －１ Let A1 be the peak area, and the range be 520-570 cm². －１ When the peak area is taken as A2, the maximum value of A2 / A1 in the range from the surface to a depth of 0 to 3 μm is 2.2 or less, and Li ２ Si ２ O ５ A method for producing chemically strengthened crystallized glass, comprising chemically strengthening a crystallized glass containing crystals by contacting it with either molten salt A or molten salt B described below. Molten salt A: A molten salt containing 30% by mass or more of K salt, 30% by mass or more of Na salt, and 0.02% by mass or more of Li salt. Molten salt B: A molten salt containing 95% by mass or more of K salt.

11. The K salt contained in molten salt A and molten salt B is KNO ３ The Na salt contained in the molten salt A is NaNO ３ The Li salt contained in the molten salt A is LiNO ３ The method for producing chemically strengthened crystallized glass according to claim 10.

12. The method for producing chemically strengthened crystallized glass according to claim 10 or 11, wherein the Young's modulus of the chemically strengthened crystallized glass is 10⁵ GPa or higher.

13. Fracture toughness value K of the chemically strengthened crystallized glass. ＩＣ However, 1.30 MPa·m １／２ The method for producing chemically strengthened crystallized glass according to claim 10 or 11.

14. The method for producing chemically strengthened crystallized glass according to claim 10 or 11, wherein the compressive stress layer depth measured using a scattered light photoelastic stress meter in the obtained chemically strengthened crystallized glass is 30 μm or more.

15. The method for producing chemically strengthened crystallized glass according to claim 10 or 11, wherein the obtained chemically strengthened crystallized glass does not have a Na ion diffusion layer.

16. The method for producing chemically strengthened crystallized glass according to claim 10 or 11, wherein the absolute value of the tensile stress at the center of the plate thickness in the obtained chemically strengthened crystallized glass is 50 MPa or less.

17. The method for producing chemically strengthened crystallized glass according to claim 10 or 11, wherein, when the chemically strengthened crystallized glass is brought into contact with the molten salt B, the temperature of the molten salt B is 430°C or higher, and the chemical strengthening time is 200 minutes or more.

18. When chemical strengthening is performed by bringing the chemically strengthened crystallized glass into contact with the molten salt B, the temperature of the molten salt B is set to T Ｋ , chemical strengthening time t Ｋ A method for producing chemically strengthened crystallized glass according to claim 10 or 11, wherein the G value, which can be determined by the following formula (PI), is 4.5 to 10.

0. In formula (PI), t is the thickness of the chemically strengthened crystallized glass plate, and the unit of t is m. Ｋ The unit is °C. In formula (PI), t Ｋ The unit is seconds. In formula (PI), E is 125,000 J / mol. In formula (PI), R is 8.31 J / (K·mol).

19. The method for producing chemically strengthened crystallized glass according to claim 10 or 11, wherein, when the chemically strengthened crystallized glass is brought into contact with the molten salt A, the temperature of the molten salt A is 430°C or higher, and the chemical strengthening time is 150 minutes or longer.

20. When chemical strengthening is performed by bringing the chemically strengthened crystallized glass into contact with the molten salt A, the temperature of the molten salt A is set to T Ｋ , chemical strengthening time t Ｋ A method for producing chemically strengthened crystallized glass according to claim 10 or 11, wherein the G value, calculated by the following formula (PI), is 3.8 to 9.

5. In formula (PI), t is the thickness of the chemically strengthened crystallized glass plate, and the unit of t is m. Ｋ The unit is °C. In formula (PI), t Ｋ The unit is seconds. In formula (PI), E is 125,000 J / mol. In formula (PI), R is 8.31 J / (K·mol).

21. The composition of the chemically strengthened crystallized glass is expressed as SiO2 in molar percentage based on oxides. ２ 60.0-75.0%, Al ２ O ３ 2.0-6.0%, P ２ O ５ Li ２ 20.0-30.0% O, Na ２ O at 0.0-5.0%, K ２ O 0.0-1.0%, MgO 0.0-2.0%, CaO 0.0-2.0%, SrO 0.0-1.0%, ZrO ２ 1.0-5.0%, SnO ２ It contains 0.0 to 1.0% of Y ２ O ３ A method for producing chemically strengthened crystallized glass according to claim 10 or 11, which substantially does not contain the specified element.

22. A cover glass comprising the chemically strengthened crystallized glass according to claim 1 or 2.

23. The cover glass according to claim 22, which is a cover glass for a display.

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