Chemically tempered crystallized glass, and crystallized glass to be chemically tempered

Abstract

To provide novel glass that has not been conventionally available.SOLUTION: Chemically tempered crystallized glass obtained by chemically tempering crystallized glass to be chemically tempered, wherein an absolute value of a maximum voltage measured is 1950 V or more when corona discharge is generated under an applied voltage of 10 kV and the chemically tempered crystallized glass is charged for 30 seconds, measured by a static honest meter.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to chemically strengthened glass-ceramics obtained by chemically strengthening glass-ceramics for chemical strengthening, and to chemically strengthened glass-ceramics. [Background technology]

[0002] In recent years, cover glass has been used for the purpose of protecting and enhancing the aesthetic appearance of display devices such as mobile phones, smartphones, and tablet terminals. Cover glass for these applications is required to have excellent strength to prevent breakage due to impact, etc. Furthermore, the above-mentioned cover glass is sometimes used to protect solar cell modules and the like.

[0003] BACKGROUND ART Conventionally, a method for increasing the surface strength of glass by chemically strengthening the glass by immersing the glass in a molten salt of potassium nitrate or the like has been known. For example, Patent Document 1 discloses that the surface strength of a glass plate is improved by chemically strengthening the glass by immersing it in a potassium nitrate molten salt. More specifically, it discloses that the strength of a glass plate is improved by chemically strengthening a Li-containing glass with a Na-containing molten salt and then a K-containing molten salt. It also discloses that the mechanism by which the strength of a glass plate is strengthened by such chemical treatment is due to compressive stress generated by the exchange of alkali metals. Patent Document 1 also discloses that crystallized glass, in which crystals are precipitated in glass, is used as the glass to be chemically strengthened. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022-215575 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, with the diversification of devices, there has been a demand for novel glasses with various properties.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a novel glass that has never existed before. [Means for solving the problem]

[0007] As a result of extensive research into the above-mentioned problems, the present inventors have discovered chemically strengthened crystallized glass that exhibits a voltage measured by a static honestometer device of a predetermined value or more, and have arrived at the present invention.

[0008] That is, the inventors have found that the above problems can be solved by the following configuration. [1] Chemically strengthened glass-ceramics obtained by chemically strengthening glass-ceramics for chemical strengthening, A chemically strengthened glass-ceramics is charged for 30 seconds using a static honestometer device to generate a corona discharge at an applied voltage of 10 kV, and the absolute value of the maximum measured voltage is 1950 V or more. [2] The composition of the above-mentioned chemically strengthened crystallized glass is expressed in mole percentage based on oxides, SiO2 60-75%, Al2O3 3-20%, P2O5 0-5%, Li2O 6~23%, Na2O 0-5%, K2O 0-5%, MgO 0-10% CaO 0-5%, The chemically strengthened glass-ceramics according to [1] contains 0 to 5% of ZrO2. [3] Li3PO4, Li2SiO3, Li2Si2O5, LiAlSi4O 10 The chemically strengthened glass-ceramics according to [1] or [2], comprising crystals selected from the group consisting of LiAlSi2O6 and LiAlSi2O6. [4] The chemically strengthened glass-ceramics according to any one of [1] to [3], wherein the absolute value of the maximum measured voltage is 2250 V or less. [5] Fracture toughness value K IC but 0.90 MPa m 1 / 2 The chemically strengthened glass-ceramics according to any one of [1] to [4] above. [6] The chemically strengthened glass-ceramics according to any one of [1] to [5], which has a Young's modulus of 85 GPa or more. [7] Average value of tensile stress CT of the above-mentioned glass-ceramics for chemical strengthening ave The chemically strengthened glass-ceramics according to any one of [1] to [6], wherein the compressive strength is 95 MPa or more. [8] Maximum tensile stress CT of the above-mentioned chemically strengthened glass-ceramics Max The chemically strengthened glass-ceramics according to any one of [1] to [7], wherein the compressive strength is 100 MPa or more. [9] The chemically strengthened glass-ceramics according to any one of [1] to [8], which satisfies the following formula (I): Formula (I) CS 90 ≧ 0.2t - 10 In formula (I), CS 90 is the compressive stress value at a depth of 90 μm from the surface of the chemically strengthened glass-ceramics, and is expressed in MPa. In formula (I), t is the plate thickness of the chemically strengthened crystallized glass, and is expressed in μm.

[10] The chemically strengthened crystallized glass according to any one of [1] to [9], wherein the compressive stress layer depth DOC is 0.17 to 0.25 times the plate thickness of the chemically strengthened crystallized glass, wherein the compressive stress layer depth and the plate thickness of the chemically strengthened crystallized glass are in μm.

[11] The chemically strengthened glass-ceramics according to any one of [1] to

[10] , wherein an antifouling layer containing a fluorine-containing compound is formed on one surface of the chemically strengthened glass-ceramics, and after a rubber rubbing test is performed 2500 times under a load of 9.8 N on the surface of the chemically strengthened glass-ceramics on the side on which the antifouling layer is formed, the water contact angle is 80° or more.

[12] A chemically strengthened crystallized glass having an absolute value of 1200 V or more of the maximum measured voltage when a corona discharge is generated using a static honestometer device with an applied voltage of 10 kV and the glass is charged for 30 seconds.

[13] In mole percentage based on oxides, SiO2 60-75%, Al2O3 3-20%, P2O5 0-5%, Li2O 6~23%, Na2O 0-5%, K2O 0-5%, MgO 0-10% CaO 0-5%, The chemically strengthened crystallized glass according to

[12] , containing 0 to 5% of ZrO2.

[14] Li3PO4, Li2SiO3, Li2Si2O5, LiAlSi4O 10

[14] or

[15] , wherein the glass-ceramics for chemical strengthening according to

[12] or

[13] contain crystals selected from the group consisting of LiAlSi2O6 and LiAlSi2O6.

[15] Fracture toughness value K IC but 0.90 MPa m 1 / 2 The chemically strengthened crystallized glass according to any one of

[12] to

[14] above.

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

[12] to

[15] , which has a Young's modulus of 85 GPa or more. [Effects of the Invention]

[0009] According to the present invention, a novel glass can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram of a sample used to measure fracture toughness KIC by the DCDC method. [Figure 2] This is a graph showing the K1-v curve, which shows the relationship between the stress intensity factor K1 (unit: MPa·m1 / 2) and the crack growth rate v (unit: m / s), used in measuring the fracture toughness value KIC using the DCDC method. DETAILED DESCRIPTION OF THE INVENTION

[0011] The chemically strengthened crystallized glass of the present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be practiced with any modifications within the scope of the gist of the present invention.

[0012] In this specification, "chemically strengthened glass-ceramics" refers to glass-ceramics after chemical strengthening treatment, and "glass-ceramics for chemical strengthening" refers to glass-ceramics before chemical strengthening treatment.

[0013] In this specification, the glass composition of chemically strengthened glass-ceramics is sometimes referred to as the mother glass composition of chemically strengthened glass-ceramics. In chemically strengthened glass-ceramics, a compressive stress layer is usually formed on the glass surface due to ion exchange, so the glass composition of the non-ion-exchanged portion is identical to the mother glass composition of chemically strengthened glass-ceramics. In this specification, glass compositions are expressed in mole percentages based on oxides, and mole % is sometimes simply referred to as %. Furthermore, the symbol "to" indicating a range of values ​​is used to mean that the values ​​before and after it are included as the lower and upper limits.

[0014] In the glass composition, "substantially not contained" means that the components are not contained except for unavoidable impurities contained in raw materials, etc., that is, they are not intentionally contained. Specifically, the content of components other than those described as the glass composition is preferably less than 0.1 mol%, more preferably 0.08 mol% or less, and even more preferably 0.05 mol% or less.

[0015] In this specification, the term "stress profile" refers to a pattern that expresses compressive stress values ​​as a function of depth from the glass surface. A negative compressive stress value indicates tensile stress. In this specification, the "stress profile" can be measured by a method using a scattered light photoelastic stress meter.

[0016] The method using a scattered light photoelastic stress meter can measure stress regardless of the refractive index distribution that occurs from the surface to the inside of chemically strengthened glass. An example of a scattered light photoelastic stress meter is the SLP2000 manufactured by Orihara Seisakusho Co., Ltd.

[0017] In this specification, the compressive stress layer depth is the depth at which the compressive stress value becomes zero.

[0018] In this specification, the "fracture toughness value K IC " is measured with reference to the DCDC method [Reference: MY He, MR Turner and AG Evans, Acta Metall. 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) as shown in Figure 2 is measured. 1 / 2 The K1-v curve, which shows the relationship between the stress intensity factor K1 at 0.1 m / s and the crack propagation velocity v (unit: m / s), was measured, and the obtained Region III data was regressed and extrapolated using a linear equation to calculate the fracture toughness value K1. IC Let's say.

[0019] <Chemically strengthened glass-ceramics> The chemically strengthened glass-ceramics of the present invention can be obtained by chemically strengthening a chemically strengthened glass-ceramics. Furthermore, the chemically strengthened crystallized glass of the present invention has an absolute value of a maximum measured voltage of 1950 V or more when a corona discharge is generated using a static honestometer device with an applied voltage of 10 kV and the chemically strengthened crystallized glass is charged for 30 seconds. The chemically strengthened glass-ceramics of the present invention will be described below.

[0020] [Maximum measurement voltage] The chemically strengthened crystallized glass of the present invention has an absolute value of a maximum measured voltage of 1950 V or more when a corona discharge is generated using a static honestometer device with an applied voltage of 10 kV and the chemically strengthened crystallized glass is charged for 30 seconds. The method for measuring the maximum measurement voltage will now be described in detail.

[0021] In the present invention, a static honest meter (H0110-S4) manufactured by Shishido Electrostatic Corporation is used as the static honest meter device. The measurement environment is set to a temperature of 22 to 25°C and a relative humidity of 47 to 55%. The static honest meter device includes a turntable for holding a measurement sample, an application unit connected to a high voltage DC power supply for generating a corona discharge, and a power receiving unit for measuring the potential of the measurement sample. The turntable has a test specimen mounting frame that holds the measurement sample so that a portion of the measurement sample is exposed on the surface.

[0022] Next, a measurement sample measuring 45 mm in length and 45 mm in width is cut out from the chemically strengthened crystallized glass. The measurement sample is fixed to the test piece mounting frame of the turntable. After fixing, the height of the application unit is adjusted so that the distance from the frame surface of the test piece mounting frame to the tip of the needle electrode of the application unit is 18 mm. Also, the height of the power receiving unit is adjusted so that the distance from the frame surface of the test piece mounting frame to the electrode of the power receiving unit is 13 mm. Thereafter, the measurement sample is neutralized with a neutralization device.

[0023] Then, while rotating the turntable, a corona discharge is generated by applying a voltage of 10 kV to charge the measurement sample for 30 seconds. The maximum voltage measured at the receiving part during charging is recorded as the maximum measured voltage (unit: V). The above measurement is carried out for five measurement samples, and the arithmetic mean value of the obtained maximum measurement voltages is defined as the maximum measurement voltage of the chemically strengthened glass-ceramics.

[0024] In the chemically strengthened crystallized glass of the present invention, the absolute value of the maximum measured voltage is 1950 V or more, preferably 1960 V or more. The absolute value of the maximum measured voltage is preferably 2250 V or less, more preferably 2200 V or less, even more preferably 2100 V or less, and particularly preferably less than 2070 V, in order to prevent the antifouling layer formed on the surface of the chemically strengthened crystallized glass from peeling off.

[0025] From the investigations of the present inventors, it has been found that when the absolute value of the maximum measured voltage is large, the surface resistance value of the chemically strengthened glass-ceramics tends to be large. Furthermore, the inventors' investigations have revealed a relationship between abnormal light emission at the edges of an organic electroluminescence display (OLED) and the surface resistance value. Specifically, when chemically strengthened crystallized glass is used as a cover glass, repeated contact with a finger or the like can cause charge to accumulate on the surface of the cover glass. It is believed that the accumulated charge is less likely to move in the in-plane direction if the surface resistance of the chemically strengthened crystallized glass is high. Therefore, if the surface resistance of the glass increases, the absolute value of the maximum charging voltage increases above a certain value, making it difficult for the charge accumulated at the edges of the screen to be supplied, which is thought to suppress abnormal OLED light emission.

[0026] Compressive Stress The chemically strengthened glass-ceramics of the present invention often have a compressive stress layer on the surface side where compressive stress acts. Preferred parameters relating to the compressive stress will be described below.

[0027] The compressive stress (CS0) of the outermost surface of the chemically strengthened glass-ceramics of the present invention is preferably 150 MPa or more, more preferably 200 MPa or more, even more preferably 300 MPa or more, and particularly preferably 400 MPa or more. The CS0 of the chemically strengthened glass-ceramics of the present invention is often 1500 MPa or less, preferably 1200 MPa or less, more preferably 1100 MPa or less, and even more preferably 1000 MPa or less. The CSO of the chemically strengthened glass-ceramics of the present invention is measured by the scattered light photoelastic stress meter described above.

[0028] The compressive stress (CS 50 ) is preferably 40 MPa or more, more preferably 80 MPa or more, and even more preferably 120 MPa or more, in order to prevent cracks from occurring even with a larger impact when another object collides with the chemically strengthened glass-ceramics of the present invention. 50 From the viewpoint of not exceeding the CT limit of the glass, is often 500 MPa or less, preferably 300 MPa or less, more preferably 250 MPa or less, further preferably 200 MPa or less, and particularly preferably 180 MPa or less.

[0029] The compressive stress (CS 90 ) is preferably -10 MPa or more, more preferably 10 MPa or more, and even more preferably 30 MPa or more, in order to prevent cracks from occurring even with a larger impact when another object collides with the chemically strengthened glass-ceramics of the present invention. 90 From the viewpoint of not exceeding the CT limit of the glass, the compressive strength is often 200 MPa or less, preferably 180 MPa or less, more preferably 150 MPa or less, and even more preferably 120 MPa or less. The compressive stress at each depth can be calculated from the stress profile obtained by the above-mentioned method.

[0030] The depth of compressive stress layer (DOC) of the chemically strengthened glass-ceramics of the present invention is preferably 80 μm or more, more preferably 90 μm or more, and even more preferably 100 μm or more. The DOC of the chemically strengthened glass-ceramics of the present invention is preferably 180 μm or less, more preferably 150 μm or less, and even more preferably 120 μm or less.

[0031] The product of CSO and DOC of the chemically strengthened glass-ceramics of the present invention (CS area) is often 15,000 Pa·m or more, preferably 20,000 Pa·m or more, more preferably 40,000 Pa·m or more, and even more preferably 60,000 Pa·m or more. area is often 200,000 Pa·m or less, preferably 180,000 Pa·m or less, and more preferably 160,000 Pa·m or less.

[0032] Furthermore, it is also preferable that the DOC value of the chemically strengthened glass-ceramics of the present invention is 0.17 to 0.25 times or more the plate thickness of the chemically strengthened glass-ceramics of the present invention, i.e., the value obtained by dividing the DOC (unit: μm) of the chemically strengthened glass-ceramics of the present invention by the plate thickness (unit: μm) is 0.17 to 0.25.

[0033] CS of the chemically strengthened glass-ceramics of the present invention 90 It is also preferable that the plate thickness satisfies the following formula (I): Formula (I) CS 90 ≧ 0.2t - 10 In formula (I), CS 90 is the compressive stress value at a depth of 90 μm from the surface of the chemically strengthened glass-ceramics, and is expressed in MPa. In formula (I), t is the plate thickness of the chemically strengthened crystallized glass, and is expressed in μm. When the above formula (I) is satisfied, the value obtained by subtracting the value on the left side of the formula (I) from the value on the right side is a positive value, and the value obtained by subtraction is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more. In addition, the value obtained by subtraction is often 100 or less, and preferably 50 or less.

[0034] Tensile Stress The chemically strengthened glass-ceramics of the present invention often have a compressive stress layer on the surface, but in this case, a tensile stress that balances this acts inside the chemically strengthened glass-ceramics. Preferred parameters regarding the tensile stress will be described below.

[0035] The maximum tensile stress (CTMax ) is preferably 40 MPa or more, more preferably 50 MPa or more, further preferably 70 MPa or more, and particularly preferably 100 MPa or more. Max is often 250 MPa or less, preferably 180 MPa or less, more preferably 150 MPa or less, and even more preferably 120 MPa or less. CT Max is determined from the stress profile and usually acts at the mid-thickness position.

[0036] The average tensile stress (CT ave ) is preferably 30 MPa or more, more preferably 40 MPa or more, further preferably 50 MPa or more, and particularly preferably 60 MPa or more. ave is often 200 MPa or less, preferably 140 MPa or less, and more preferably 120 MPa or less. The average value of the tensile stress is obtained by dividing the integral value of the tensile stress in the thickness direction in the depth region showing the tensile stress in the stress profile by the length of the tensile stress portion.

[0037] The integrated tensile stress (ICT) of the chemically strengthened glass-ceramics of the present invention is often 60,000 Pa m or less, preferably 50,000 Pa m or less, more preferably 40,000 Pa m or less, and even more preferably 30,000 Pa m or less. There is no particular lower limit for ICT, but it is often 10,000 Pa m or more, and preferably 20,000 Pa m or more. ICT is calculated by integrating the tensile stress in the depth region that shows the tensile stress from the stress profile.

[0038] Plate Thickness The thickness of the chemically strengthened crystallized glass of the present invention can be adjusted appropriately depending on the application, but is often 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. The thickness of the chemically strengthened crystallized glass of the present invention is often 2.0 mm or less, preferably 1.5 mm or less, more preferably 1.2 mm or less, and even more preferably 1.0 mm or less.

[0039] [Physical Properties] The fracture toughness value K of the chemically strengthened glass-ceramics of the present invention IC is 0.80 MPa m 1 / 2 More than 0.85 MPa m is preferable. 1 / 2 More preferably, 0.90 MPa m 1 / 2 More preferably, it is 1.0 MPa m 1 / 2 or more, most preferably 1.1 MPa m 1 / 2 That's all. Fracture toughness value K IC There is no particular upper limit, but it is typically 1.6 MPa m 1 / 2 The following is the result. Fracture toughness value K of chemically strengthened glass-ceramics IC is the fracture toughness value K of the chemically strengthened glass-ceramic IC usually coincides with

[0040] The Young's modulus of the chemically strengthened glass-ceramics of the present invention is preferably 80 GPa or more, more preferably 85 GPa or more, even more preferably 90 GPa or more, particularly preferably 95 GPa or more, and most preferably 100 GPa or more. The upper limit of the Young's modulus is not particularly limited, but is typically 120 GPa or less. The Young's modulus of chemically strengthened glass-ceramics is usually the same as that of glass-ceramics for chemical strengthening.

[0041] [composition] The chemically strengthened glass-ceramics of the present invention can be obtained by chemically strengthening a plate glass before chemical strengthening (glass-ceramics for chemical strengthening). The glass composition of the chemically strengthened glass-ceramics is the same as the composition of the chemically strengthened glass-ceramics at the center of the thickness of the plate. That is, the preferred composition of the chemically strengthened glass-ceramics at the center of the thickness of the plate is the same as the preferred composition of the chemically strengthened glass-ceramics. The composition of the chemically strengthened glass-ceramics is expressed as mole percentage based on oxides: SiO2 60-75%, Al2O3 3-20%, P2O5 0-5%, Li2O 6~23%, Na2O 0-5%, K2O 0-5%, MgO 0-10% CaO 0-5%, It is preferable that ZrO2 is contained in an amount of 0 to 5%. More preferred compositions of the chemically strengthened crystallized glass and a method for producing the chemically strengthened crystallized glass will be described in detail later. The crystals contained in the chemically strengthened crystallized glass are also contained in the chemically strengthened crystallized glass, and the preferred embodiments of the crystals contained in the chemically strengthened crystallized glass are the same as the preferred embodiments of the crystals contained in the chemically strengthened crystallized glass. That is, chemically strengthened glass-ceramics are Li3PO4, Li2SiO3, Li2Si2O5, LiAlSi4O 10 and LiAlSi2O6.

[0042] [Chemical strengthening treatment] As described above, the chemically strengthened glass-ceramics of the present invention can be obtained by chemically strengthening a chemically strengthened glass-ceramics. The chemical strengthening treatment will be described below. Hereinafter, the chemically strengthened crystallized glass to be subjected to the chemical strengthening treatment may be simply referred to as a "glass plate."

[0043] The chemical strengthening treatment can be carried out by a known method. For example, the chemical strengthening treatment is carried out by bringing the glass sheet into contact with a molten salt of a metal salt (e.g., potassium nitrate or sodium nitrate) containing a metal ion (typically, K ion or Na ion) of a large ionic radius. The contact between the glass sheet and the molten salt of the metal salt is carried out, for example, by immersing the glass sheet in the molten salt of the metal salt. When the glass plate comes into contact with the metal salt, metal ions with a small ionic radius (typically Na ions or Li ions) in the glass plate are replaced with metal ions with a large ionic radius (typically K ions for Na ions, and Na ions or K ions for Li ions).

[0044] Chemical strengthening treatment, i.e., ion exchange treatment, can be performed, for example, by immersing a glass plate in molten salt heated to 360 to 600°C for 0.1 to 100 hours. The heating temperature of the molten salt is preferably 375°C or higher, more preferably 415°C or higher. The heating temperature of the molten salt is preferably 500°C or lower, more preferably 470°C or lower, and particularly preferably 450°C or lower. The immersion time of the glass plate in the molten salt is preferably 0.5 hours or longer, more preferably 1 hour or longer, even more preferably 1.5 hours or longer, particularly preferably 2 hours or longer, and most preferably 6 hours or longer. The immersion time of the glass plate in the molten salt is preferably 100 hours or shorter, more preferably 50 hours or shorter, and even more preferably 20 hours or shorter.

[0045] Examples of metal salts contained in the molten salt for chemical strengthening treatment include nitrates, sulfates, carbonates, and chlorides. Nitrates include lithium nitrate, sodium nitrate, potassium nitrate, cesium nitrate, and silver nitrate. Sulfates include lithium sulfate, sodium sulfate, potassium sulfate, cesium sulfate, and silver sulfate. Carbonates include lithium carbonate, sodium carbonate, and potassium carbonate. Chlorides include lithium chloride, sodium chloride, potassium chloride, cesium chloride, and silver chloride. These metal salts may be used alone or in combination. In particular, the molten salt preferably contains sodium nitrate. The content of sodium nitrate in the molten salt may be 70% by mass or more, or 90% by mass or more. The content of sodium nitrate in the molten salt may be 100% by mass.

[0046] The chemical strengthening treatment may be carried out only once, or may be carried out multiple times under two or more different conditions (multi-stage strengthening). That is, the chemical strengthening treatment may be carried out in one stage, or in two or more stages. An example of a two-stage or more chemical strengthening treatment is a method in which chemically strengthened crystallized glass containing Li is contacted with a molten salt of a metal salt containing at least Na ions (first molten salt), and then with a molten salt of a metal salt containing at least K ions (second molten salt). The first molten salt also preferably contains a metal salt containing Na ions and a metal salt containing K ions. When the first molten salt contains a metal salt containing Na ions and a metal salt containing K ions, the content of the metal salt containing Na ions is preferably 5 mass% or more, more preferably 10 mass% or more, even more preferably 20 mass% or more, and particularly preferably 40 mass% or more, relative to the total mass of the first molten salt. Alternatively, the first molten salt may consist solely of the metal salt containing Na ions. The second molten salt preferably contains a metal salt containing K ions and a metal salt containing Li ions. The second molten salt may further contain a metal salt containing Na ions. In order to easily obtain the chemically strengthened glass-ceramics of the present invention, the chemical strengthening treatment is preferably performed in one step.It is also preferable that the chemical strengthening treatment is performed in one step and that the content of sodium nitrate in the molten salt is 90 mass% or more.

[0047] [Durability of anti-fouling layer] It is also preferable that the chemically strengthened crystallized glass of the present invention has an anti-fouling layer containing a fluorine-containing compound formed on one side of the chemically strengthened crystallized glass, and that the surface of the chemically strengthened crystallized glass on which the anti-fouling layer is formed has a water contact angle of 80° or more after a rubber rubbing test is performed 2,500 times with a load of 9.8 N on the surface. The detailed method for forming the antifouling layer, the method for the rubber rubbing test, and the method for measuring the contact angle of test water are in accordance with the methods described in the Examples below. A water contact angle of 80° or more after the rubber rubbing test indicates that the antifouling layer remains even after the rubber rubbing test, and corresponds to high durability of the antifouling layer. The water contact angle after the rubber rubbing test is more preferably 85° or more.

[0048] [Application] The chemically strengthened glass-ceramics of the present invention are useful, for example, as cover glass. The cover glass can also be suitably used for purposes such as protecting the surfaces of displays and solar cell modules. In particular, the chemically strengthened crystallized glass of the present invention is useful as a cover glass for mobile devices such as mobile phones, smartphones, personal digital assistants (PDAs), and tablet devices. It is also useful as a cover glass for non-portable display devices such as televisions (TVs), personal computers (PCs), and touch panels; a cover glass for the surface of a solar cell module; an elevator wall; a wall surface (full-screen display) of a building such as a house or building; a window glass; and a tabletop; an interior of an automobile or airplane. It is also useful as a cover glass for the above-mentioned items. Furthermore, it can be used for applications such as a curved housing by bending and bending forming.

[0049] <Chemically strengthened glass-ceramics> The chemically strengthened crystallized glass of the present invention has an absolute value of 1200 V or more of the maximum measured voltage when charged for 30 seconds by applying a voltage of 10 kV to generate a corona discharge using a static honestometer. The method for measuring the maximum measurement voltage is the same as that described above in connection with the chemically strengthened crystallized glass of the present invention, and therefore the description thereof will be omitted. As described above in the section on the chemically strengthened glass-ceramics of the present invention, a large absolute value of the maximum measured voltage tends to indicate a large surface resistance value of the chemically strengthened glass-ceramics. That is, the chemically strengthened glass-ceramics of the present invention is a novel glass with a large surface resistance. The chemically strengthened crystallized glass of the present invention is also suitable for use in producing the chemically strengthened crystallized glass of the present invention. The chemically strengthened crystallized glass of the present invention will be described in detail below.

[0050] [composition] The composition of the chemically strengthened crystallized glass of the present invention will be described below. Hereinafter, the preferred composition of the chemically strengthened crystallized glass will also be referred to as the "mother glass composition."

[0051] A preferred composition (base glass composition) of the chemically strengthened glass-ceramics of the present invention is, expressed in mole percentage based on oxides, SiO2 60-75%, Al2O3 3-20%, P2O5 0-5%, Li2O 6~23%, Na2O 0-5%, K2O 0-5%, MgO 0-10% CaO 0-5%, Contains 0-5% ZrO2. Each component contained in the mother glass composition will be described below.

[0052] SiO2 is a component that makes up the network of glass. It also increases chemical durability and reduces the occurrence of cracks when the glass surface is scratched.

[0053] In order to improve chemical durability, the SiO2 content is preferably 63% or more, and even more preferably 65% ​​or more. On the other hand, in order to improve meltability, the SiO2 content is preferably 74.0% or less, and even more preferably 72.0% or less.

[0054] Al2O3 is a component that improves ion exchange performance during chemical strengthening and increases the surface compressive stress after strengthening. It also contributes to the formation of crystals containing Al and Li. From the viewpoint of achieving the above effects, the Al2O3 content is more preferably 3.5% or more, and even more preferably 4.0% or more and 4.5% or more, in the following order. On the other hand, there are also cases where it is required to make it difficult for crystals to grow during melting, to make it difficult for devitrification defects to occur, to increase yield, and to reduce the high-temperature viscosity of the glass to make it easier to melt. From these viewpoints, the Al2O3 content is more preferably 18.0% or less, and even more preferably 15.0% or less, 12.0% or less, 9.0% or less, 7.0% or less, and 6.0% or less, in the following order.

[0055] SiO2 and Al2O3 are both components that stabilize the glass structure. To reduce brittleness, the total content of SiO2 and Al2O3 is preferably 64.0% or more, more preferably 66.0% or more, and even more preferably 68.0% or more. Furthermore, both SiO2 and Al2O3 tend to increase the melting temperature of the glass. Therefore, in order to make the glass more easily meltable, the total content of SiO2 and Al2O3 is preferably 80.0% or less, more preferably 78.0% or less, even more preferably 76.0% or less, and particularly preferably 74.0% or less.

[0056] Li2O is an ion-exchangeable component that improves the meltability of glass. When glass contains Li2O, Li ions on the glass surface are ion-exchanged with external Na ions to incorporate them into the glass, and the incorporated Na ions are then ion-exchanged with external K ions, which facilitates the production of a stress profile with a large surface compressive stress and a thick compressive stress layer. Furthermore, by including Li2O in the above range, crystallized glass is easily obtained when a specific heat treatment is performed. From the above viewpoints, the Li2O content is more preferably 15% or more, and even more preferably 18% or more, 20% or more, and 21% or more, in the following order.

[0057] On the other hand, from the viewpoint of reducing the crystal growth rate during glass molding and making it difficult for deterioration in quality due to devitrification to occur, the Li2O content is more preferably 22% or less.

[0058] Na2O and K2O are components that improve the meltability of glass and reduce the crystal growth rate during glass molding. In addition, it is preferable to include a small amount of Na2O and K2O in order to improve ion exchange performance.

[0059] Na2O is a component that can undergo ion exchange in chemical strengthening treatment using potassium salts and also reduces the viscosity of glass. To achieve the above effects, the Na2O content is preferably 0.3% or more, and more preferably 0.5% or more, 0.8% or more, 1.0% or more, 1.2% or more, 1.5% or more, and 1.8% or more, in the following order. On the other hand, from the viewpoint of maintaining the glass network and avoiding a decrease in surface compressive stress (Na_CS) in strengthening treatment using sodium salts, the Na2O content is preferably 3.0% or less, more preferably 2.5% or less, and even more preferably 2.3% or less.

[0060] K2O is a component that suppresses an increase in the devitrification temperature, thereby suppressing devitrification, and also improves ion exchange performance. The K2O content is more preferably 0.03% or more, even more preferably 0.05% or more, and particularly preferably 0.1% or more. On the other hand, from the viewpoint of avoiding a decrease in surface compressive stress (K_CS) in the strengthening treatment with sodium salts, the content of K2O is preferably 1.0% or less, more preferably 0.8% or less, and even more preferably 0.5% or less. It is not necessary for K2O to be substantially contained.

[0061] R, which is the total of the Li2O content, the Na2O content, and the K2O content, is more preferably 10 to 30%, further preferably 15 to 28%, and particularly preferably 18 to 25%, from the viewpoint of suppressing an increase in the devitrification temperature and reducing the crystal growth rate.

[0062] The ratio of the Li2O content to the R ([Li2O] / ([Li2O] + [Na2O] + [K2O]), hereinafter also referred to as "Li2O / R2O") is more preferably 0.88 or more, and even more preferably 0.90 or more, from the viewpoint of further improving deep layer stress in chemical strengthening properties. From the viewpoint of further increasing the electrical resistance and chemical resistance of the glass, Li2O / R2O is more preferably 0.99 or less, even more preferably 0.98 or less, and particularly preferably 0.95 or less.

[0063] The ratio of the Na2O content to the R ([Na2O] / ([Li2O] + [Na2O] + [K2O]), hereinafter also referred to as "Na2O / R2O") is preferably greater than 0, more preferably 0.01 or greater, even more preferably 0.02 or greater, particularly preferably 0.05 or greater, and most preferably 0.06 or greater, from the viewpoint of further improving deep layer stress in chemical strengthening properties. Na2O / R2O 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, from the viewpoint of further improving chemical resistance.

[0064] The ratio of the content of K2O to the above-mentioned R ([K2O] / ([Li2O]+[Na2O]+[K2O]), hereinafter also referred to as "K2O / R2O") is preferably 0.001 or more, more preferably 0.004 or more, and even more preferably 0.01 or more, from the viewpoint of further increasing the electrical resistance of the glass. From the viewpoint of increasing the compressive stress near the surface in chemical strengthening properties, K2O / R2O is preferably 0.50 or less, more preferably 0.40 or less, even more preferably 0.30 or less, and particularly preferably 0.20 or less. It should be noted that K2O / R2O may be 0.

[0065] Furthermore, from the viewpoint of suppressing an increase in the devitrification temperature and reducing the crystal growth rate, the products of Li2O / R2O, Na2O / R2O, and K2O / R2O are more preferably 0.00005 or more, even more preferably 0.0001 or more, and particularly preferably 0.01 or more. Moreover, the products are more preferably 0.020 or less. The above product may be zero.

[0066] The ratio of the Al2O3 content to the R ([Al2O3] / ([Li2O] + [Na2O] + [K2O]), hereinafter also referred to as "Al2O3 / R2O") is preferably 0.05 or more, more preferably 0.10 or more, even more preferably 0.15 or more, and still more preferably 0.20 or more. Al2O3 / R2O is preferably 0.50 or less, more preferably 0.40 or less, even more preferably 0.30 or less, and particularly preferably 0.25 or less.

[0067] The value represented by [Al2O3]-[Na2O]-[K2O]+[Li2O] is preferably 15.0% or more, more preferably 20.0% or more, and is preferably 35.0% or less, more preferably 30.0% or less.

[0068] MgO may be contained to reduce viscosity during dissolution, etc. The MgO content is more preferably 0.05% or more, and even more preferably 0.5% or more, 1.0% or more, 2.0% or more, 3.0% or more, and 4.0% or more, in the following order. On the other hand, in terms of making it easier to increase the compressive stress layer during chemical strengthening treatment, the MgO content is more preferably 9.0% or less, and even more preferably 8.0% or less, 7.0% or less, and 6.0% or less, in that order.

[0069] Furthermore, by including MgO, it is possible to suppress the phase transition of the crystal phase from β-quartz solid solution to β-spodumene, and to suppress the precipitation of β-spodumene crystals. Therefore, in the second embodiment, it is preferable to include MgO. From the above viewpoint, it is preferable to include more than 0.5% and not more than 7.0% of MgO. The more preferable range is as described above. MgO may not be substantially contained.

[0070] CaO is a component that improves the meltability of glass and may be contained. 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 the tendency to increase the compressive stress value during chemical strengthening treatment, the CaO content is more preferably 2.0% or less, even more preferably 1.0% or less, particularly preferably 0.8% or less, and most preferably 0.5% or less. CaO may not be substantially contained.

[0071] To improve the stability of the glass, it is more preferable to contain at least one of MgO and CaO, and even more preferable to contain MgO. The total content of MgO and CaO is preferably 0.01% or more, more preferably more than 1.0%, even more preferably 2.0% or more, particularly preferably 3.0% or more, and most preferably 4.0% or more. To further improve chemical strengthening properties, the total content of MgO and CaO is preferably 10.0% or less, more preferably 8.0% or less, 7.0% or less, and 6.0% or less, in that order.

[0072] SrO is a component that improves the meltability of glass and may be contained. 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 order to make it easier to increase the compressive stress value during chemical strengthening treatment, the SrO content is more preferably 3.0% or less, even more preferably 2.0% or less, particularly preferably 1.0% or less, and most preferably 0.5% or less. SrO may not be substantially contained.

[0073] BaO is a component that improves the meltability of glass and may be contained. When BaO is contained, the content is preferably 0.1% or more, more preferably 0.15% or more, and even more preferably 0.5% or more. In order to make it easier to increase the compressive stress value during chemical strengthening treatment, the BaO 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. BaO may not be substantially contained.

[0074] ZnO is a component that improves the meltability of glass. The ZnO content is more preferably 0.1% or more, even more preferably 0.15% or more, and particularly preferably 0.5% or more. In order to make it easier to increase the compressive stress value during chemical strengthening treatment, the ZnO content is more preferably 3.0% or less, even more preferably 2.0% or less, particularly preferably 1.0% or less, and most preferably 0.5% or less. ZnO may not be substantially contained.

[0075] lnW is a parameter that represents the degree of oxide mixing, calculated from the contents of alkali metal oxides, alkaline earth metal oxides, and zinc oxide contained in the glass. It is expressed by the following formula: lnW=ln(([Li2O]+[Na2O]+[K2O]+[MgO]+[CaO]+[SrO]+[BaO]+[ZnO])! / ([Li 2O]!×[Na2O]!×[K2O]!×[MgO]!×[CaO]!×[SrO]!×[BaO]!×[ZnO]!))...Formula (W1) In formula (W1), [LiO], [NaO], [KO], [MgO], [CaO], [SrO], [BaO] and [ZnO] represent the contents of LiO, NaO, KO, MgO, CaO, SrO, BaO and ZnO, respectively, expressed as mole percentages on an oxide basis. Also, ! indicates the factorial of a positive integer. For example, [XO]! means that the mole percentage content of the component XO, expressed on an oxide basis, is rounded down to the nearest integer, and then that integer is factorized. For example, if Na2O is 4.8 mole%, the calculation is 4 factorial, i.e., 4 x 3 x 2 x 1. The larger the value of lnW, the higher the degree of mixing of the above metal oxides, and the more effectively devitrification of the glass can be suppressed. From the above viewpoint, lnW is preferably 10 or more, more preferably 12 or more, even more preferably 13 or more, and particularly preferably 14 or more. lnW is preferably 20 or less, more preferably 18 or less, and even more preferably 17 or less.

[0076] TiO2 is a component that is highly effective in suppressing solarization of glass and is a material that forms crystal nuclei, so it may be contained. When TiO2 is contained, the content is preferably 0.05% or more, more preferably 0.1% or more, even more preferably 0.2% or more, particularly preferably 0.5% or more, and most preferably 0.8% or more. On the other hand, since TiO2 has light absorption properties, in order to prevent color development in the glass, the TiO2 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. TiO2 may not be substantially contained.

[0077] ZrO2 is a component that facilitates increasing the surface compressive stress of chemically strengthened glass-ceramics. Furthermore, since ZrO2 is a material that forms crystal nuclei, ZrO2 may be contained. The ZrO2 content is more preferably greater than 0%, and even more preferably 0.5% or more, 1% or more, 1.5% or more, 2% or more, and 2.5% or more, in the following order. The ZrO2 content is more preferably 4% or less.

[0078] P2O5 tends to increase the compressive stress layer during chemical strengthening. The P2O5 content is more preferably 0.5% or more, even more preferably 1.0% or more, and particularly preferably 2.0% or more. On the other hand, from the viewpoint of increasing acid resistance, the content of P2O5 is more preferably 3.0% or less. From the viewpoint of preventing the formation of striae during melting, it is also preferable that P2O5 is substantially not contained.

[0079] B2O3 reduces the brittleness of the glass and improves the crack resistance, or improves the meltability of the glass. The B2O3 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 order to maintain good acid resistance, the B2O3 content is preferably 8.0% or less. The B2O3 content is more preferably 6.0% or less, even more preferably 4.0% or less, and particularly preferably 2.0% or less. In order to prevent the occurrence of striae during melting, it is also preferable that the B2O3 content be substantially zero.

[0080] Y2O3 is a component that facilitates increasing the surface compressive stress of chemically strengthened glass-ceramics while slowing the crystal growth rate. The Y2O3 content is preferably greater than 0%, and more preferably 0.1% or more, 0.2% or more, 0.5% or more, and 0.8% or more, in that order. On the other hand, in terms of facilitating the enlargement of the compressive stress layer during chemical strengthening treatment, the Y2O3 content is more preferably 2.0% or less, and even more preferably 1.5% or less.

[0081] From the viewpoint of improving the initial solubility, the total content of ZrO2 and Y2O3 is more preferably 5.0% or less. Although there is no particular lower limit for the total content of ZrO2 and Y2O3, from the viewpoint of increasing the strength of the glass, it is more preferably 0.5% or more, and further preferably 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, and 3.0% or more, in that order.

[0082] The ratio of the ZrO2 content to the total content of ZrO2 and Y2O3, [ZrO2] / ([ZrO2]+[Y2O3]), is more preferably 0.50 or more, even more preferably 1.00 or more, and particularly preferably 2.00 or more. [ZrO2] / ([ZrO2]+[Y2O3]) is more preferably 8.00 or less, even more preferably 7.00 or less, and particularly preferably 6.00 or less.

[0083] ZrO2 and Y2O3 are known as nucleating agents when added alone, but co-addition of ZrO2 and Y2O3 forms a eutectic of ZrO2 and Y2O3, which allows control of the devitrification temperature, crystal growth rate, and crystallization onset temperature. Furthermore, by setting [ZrO2] / ([ZrO2]+[Y2O3]) within the above range, the diffusion of ions in the glass is suppressed, which prevents an increase in the devitrification temperature and thus suppresses devitrification. By keeping [ZrO2] / ([ZrO2]+[Y2O3]) within the above range, the glass is stabilized, and the temperature ranges where nucleation occurs and where crystal growth occurs are separated and do not overlap, suppressing an increase in the crystal growth rate and thus suppressing the occurrence of defects. Furthermore, by keeping [ZrO2] / ([ZrO2]+[Y2O3]) within the above range, the temperature range where nucleation occurs is shifted to the lower side, suppressing a decrease in the crystallization onset temperature and improving manufacturing properties.

[0084] La2O3 is not essential, but can be contained for the same reasons as Y2O3. The La2O3 content 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 the content is too high, it becomes difficult to increase the compressive stress layer during chemical strengthening treatment, so the La2O3 content 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. It is also preferable that La2O3 is substantially not contained.

[0085] NbO 5、Ta2O5, Gd2O3, and CeO2 are components that have the effect of suppressing solarization of glass and improving meltability, and may be contained. When these components are contained, 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, the content is preferably 3.0% or less, more preferably 2.0% or less, and even more preferably 1.0% or less.

[0086] Fe2O3 absorbs heat rays and thus improves the meltability of glass. Therefore, its inclusion is preferable when mass-producing glass using a large melting furnace. In this case, the content, expressed as mass% on the oxide basis, 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. However, since excessive Fe2O3 content causes coloration, the content, expressed as mass% on the oxide basis, 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, from the viewpoint of enhancing the transparency of the glass.

[0087] Furthermore, other coloring components may be added to the extent that the desired chemical strengthening properties are not impaired. Suitable examples of other coloring components include Co3O4, MnO2, NiO, CuO, Cr2O3, V2O5, Bi2O3, SeO2, Er2O3, and Nd2O3.

[0088] SO3, chlorides, fluorides, etc. may be appropriately contained as fining agents during melting of the glass. It is preferable that As2O3 is not contained. If Sb2O3 is contained, it is preferably 0.3% or less, more preferably 0.1% or less, and most preferably zero. From the viewpoint of clarifying bubbles in the glass, the SnO2 content is preferably 0.1% or more, further preferably 0.2% or more, and particularly preferably 0.3% or more. In addition, in order to suppress the occurrence of defects, the SnO2 content is preferably 1% or less, more preferably 0.8% or less, further preferably 0.7% or less, and particularly preferably 0.5% or less.

[0089] The chemically strengthened crystallized glass of the present invention contains crystals. The type of crystal contained is not particularly limited, but for example, one or more crystals selected from the group consisting of lithium silicate crystals, lithium aluminosilicate crystals, and lithium phosphate crystals are preferred. As the lithium silicate crystals, lithium metasilicate (Li2SiO3) crystals, lithium disilicate crystals (Li2Si2O5), etc. are preferred. As the lithium phosphate crystals, lithium orthophosphate crystals (Li3PO4), etc. are preferred. As the lithium aluminosilicate crystals, β-spodumene crystals (LiAlSiO6), petalite crystals (LiAlSiO4), etc. are preferred. 10 ) etc. are preferred. Among these, the crystal glass for chemical strengthening of the present invention is Li3PO4, Li2SiO3, Li2Si2O5, LiAlSi4O 10 and LiAlSi2O6.

[0090] The crystallization rate of the chemically strengthened crystallized glass 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 70% or less, more preferably 60% or less, and even more preferably 50% or less. A low crystallization rate is also advantageous in that it is easy to heat and bend. The crystallization rate can be calculated from X-ray diffraction intensity using the Rietveld method. The Rietveld method is described in "Crystal Analysis Handbook," edited by the Editorial Committee of the Crystallographic Society of Japan (Kyoritsu Shuppan, 1999, pp. 492-499).

[0091] The average particle size of the precipitated crystals in the chemically strengthened crystallized glass is preferably 300 nm or less to improve transparency, more preferably 200 nm or less, even more preferably 150 nm or less, and particularly preferably 100 nm or less. The average particle size of the precipitated crystals can be determined from a transmission electron microscope (TEM) image or estimated from a scanning electron microscope (SEM) image.

[0092] [Physical Properties] Preferred physical properties of the chemically strengthened crystallized glass of the present invention will be described below.

[0093] (devitrification temperature) The devitrification temperature of the chemically strengthened crystallized glass is preferably 1300°C or lower. The devitrification temperature is more preferably 1280°C or lower, and even more preferably 1250°C or lower. Particularly preferred are 1240°C or lower, 1230°C or lower, 1220°C or lower, and 1210°C or lower, in the following order. The lower limit of the devitrification temperature is not particularly limited, but is usually 1100°C or higher.

[0094] (glass transition temperature Tg, crystallization onset temperature Tcs, crystallization peak temperature Tc) The crystallization starting temperature Tcs of the chemically strengthened glass-ceramics (for example, glass having the above-mentioned mother glass composition) measured by DSC is preferably 500°C or higher. There is no particular upper limit to the crystallization starting temperature, but it is usually 800°C or lower.

[0095] When the crystallization onset temperature Tcs is within the above range, for example, by holding the glass at 500 to 600°C for 1 to 6 hours, followed by heat treatment at 600 to 800°C for 0.5 to 6 hours, crystals can be precipitated in the glass, and chemically strengthened crystallized glass can be obtained. The heat treatment may be carried out in three stages, for example, by holding at 500 to 600°C for 1 to 6 hours, holding at 550 to 650°C for 0.5 to 6 hours, and holding at 600 to 800°C for 0.5 to 6 hours to obtain chemically strengthened crystallized glass.

[0096] From the viewpoint of reducing warpage after chemical strengthening, 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 ease of float forming, the glass transition temperature 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.

[0097] The crystallization peak temperature Tc of the chemically strengthened crystallized glass having the above-mentioned mother glass composition is preferably 600°C or higher, more preferably 650°C or higher, and even more preferably 700°C or higher. A crystallization peak temperature Tc of 600°C or higher allows stable molding. Most preferably, no crystallization peak is observed. The upper limit of the crystallization peak temperature Tc is not particularly limited, but is usually 950°C or lower.

[0098] The β-OH value of the chemically strengthened glass-ceramics is 0.1 mm. -1 It is preferable that the thickness is 0.15 mm or more. -1 More than 0.2 mm is preferable. -1 More preferably, 0.22 mm or more -1 More than 0.25 mm is particularly preferable. -1 The above is most preferable.

[0099] The β-OH value is an index of the amount of water in glass. Glass with a large β-OH value tends to have a lower softening point and be easier to bend. On the other hand, from the perspective of improving the strength of glass by chemical strengthening, as the β-OH value of glass increases, the surface compressive stress (CS) value after chemical strengthening tends to decrease. From this perspective, the β-OH value is 0.5 mm -1 Less than 0.4mm is preferable -1 Less than 0.3mm is preferable. -1 The following is even more preferred:

[0100] Chemically strengthened glass-ceramics have a fracture toughness value (K IC ) is 0.80 MPa m 1 / 2 It is preferable that the pressure is 0.85 MPa m or more. 1 / 2More preferably, it is 0.90 MPa m 1 / 2 More preferably, it is equal to or greater than 1.0 MPa m 1 / 2 or more, most preferably 1.1 MPa m 1 / 2 The upper limit of the fracture toughness value is not particularly limited, but is typically 1.6 MPa m 1 / 2 The following is the result.

[0101] The Young's modulus of the chemically strengthened crystallized glass is preferably 80 GPa or more, more preferably 85 GPa or more, even more preferably 90 GPa or more, particularly preferably 95 GPa or more, and most preferably 100 GPa or more. The upper limit of the Young's modulus is not particularly limited, but is typically 120 GPa or less. The Young's modulus of the chemically strengthened crystallized glass is measured according to the method described in the Examples section below.

[0102] [Manufacturing method] The chemically strengthened crystallized glass of the present invention can be obtained, for example, by mixing raw materials so as to have the above-mentioned mother glass composition, heating the mixture, and then heat-treating the mixture at a predetermined temperature. Note that the heat treatment causes crystals to precipitate. The conditions for the heat treatment can be adjusted as appropriate depending on the crystallization start temperature Tcs of the above-mentioned mother glass composition, etc., but it is preferable to carry out the heat treatment under the following conditions, for example. Preferred heat treatment conditions include holding at 500 to 650°C for 1 to 6 hours, followed by holding at 600 to 800°C for 0.5 to 6 hours. More preferred heat treatment conditions include holding at 500 to 600°C for 1.5 to 4.5 hours, followed by holding at 620 to 740°C for 1.5 to 4.5 hours. [Example]

[0103] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples. Examples 4 to 12 are working examples of chemically strengthened glass-ceramics, and Examples 1 to 3 and Examples 13 and 14 are comparative examples of chemically strengthened glass-ceramics. Moreover, Examples 15 and 17 are working examples of chemically strengthened crystallized glass, and Example 16 is a comparative example of chemically strengthened crystallized glass.

[0104] <Production of chemically strengthened glass-ceramics> First, glass raw materials were melted in a platinum crucible to prepare glass materials A and B so as to have the glass compositions shown in Table 1, expressed in mole percentages based on oxides. Specifically, oxides, hydroxides, carbonates, nitrates, etc. used as glass raw materials were appropriately selected from commonly used glass raw materials and weighed out to give 1000 g of glass. The mixed raw materials were then placed in a platinum crucible and placed in a resistance heating electric furnace at 1500-1700°C, where they were melted for approximately three hours, degassed, and homogenized to obtain molten glass. The resulting molten glass was poured into a mold and held at a temperature of the glass transition point + 50°C for one hour, after which it was cooled to room temperature at a rate of 0.5°C / min to obtain a glass block. The resulting glass block was then cut and ground to obtain plate glass. Here, for glass material A, after it was made into a plate glass, it was heated to 550° C., held at that temperature for 2 hours, and then heated to 720° C. and held at that temperature for 2 hours, whereupon it was subjected to a heat treatment. Regarding glass material B, after it was made into a plate glass, it was heated to 550° C., held at that temperature for 4 hours, and then heated to 660° C. and held at that temperature for 4 hours, whereby it was subjected to a heat treatment. Both sides of the obtained glass plates were mirror-finished to finally obtain glass plates (glass for chemical strengthening) measuring 120 mm long x 60 mm wide x 0.55 mm thick or 120 mm long x 60 mm wide x 0.7 mm thick. In addition, for glass materials A and B, the same heat treatment as above was performed on the glass blocks, and the fracture toughness value (K IC ) and a sample piece for measuring Young's modulus were obtained.

[0105] The chemically strengthened glasses (glass materials A and B) obtained by the above procedure were subjected to a chemical strengthening treatment under the conditions shown in Table 2 to obtain the chemically strengthened glasses of Examples 1 to 12. Note that glass materials A and B are crystallized glasses for chemical strengthening. For the chemically strengthened glasses of Examples 13 and 14, the heat treatment conditions for glass material A were as shown in Table 2 below, and the chemical strengthening treatment conditions were also as shown in Table 2 below. The glasses for chemical strengthening in Examples 15 to 17 were heat treated under the conditions shown in Table 3 below.

[0106] <Stress profile measurement> The stress profile of the chemically strengthened glass was obtained by the method described above.

[0107] <Measurement of Young's modulus> The Young's modulus of the glass for chemical strengthening was measured using the sample pieces cut out in the procedure for obtaining each of the above glass materials. Specifically, the measurement was performed using the sample pieces by the ultrasonic pulse method in accordance with JIS R 1602. After chemical strengthening, the Young's modulus was measured in the same manner and was found to be the same as the value before chemical strengthening.

[0108] <Measurement of fracture toughness> In the procedure for obtaining each of the above glass materials, the fracture toughness value K of the glass for chemical strengthening was measured using the cut sample pieces. IC The fracture toughness was measured by the DC-DC method described above. After chemical strengthening, the fracture toughness value K IC When measured, the value was the same as that before chemical strengthening.

[0109] <Anti-fouling layer durability test> An antifouling layer was formed on the surface of the chemically strengthened glass of each example by the method described above, and a durability test of the formed antifouling layer was carried out. More specifically, the chemically strengthened glass was cut into a 5 cm square, an antifouling layer was formed by the following procedure, a rubber rubbing test was performed, and then the water contact angle was measured.

[0110] First, the water-washed chemically strengthened glass was plasma-cleaned, and then a fluorine-containing organic compound (UD-509 manufactured by Daikin) was deposited on the chemically strengthened glass by vacuum deposition to form an anti-fouling layer. The pressure in the vacuum chamber during deposition was 3.0 × 10 -3 The organic compound was heated by resistance heating at an output of 318.5 kA / m 2 The deposition was carried out for 300 seconds.

[0111] Next, a rubber rubbing test was carried out on the surface of the chemically strengthened glass on which the antifouling layer was formed, in the following manner. Specifically, a flat friction tester (triple type) (manufactured by Daiei Scientific Instruments Co., Ltd., device name: PA-300A) was used to conduct a rubber rubbing test 2,500 times under the following conditions: a load of 9.8 N, a friction element (eraser (Woojin Co., pink pencil)), a stroke width of 40 mm, and a reciprocating speed of 40 times / min. The test environment was 25°C and 50% RH.

[0112] After the rubber rubbing test, the water contact angle of the surface of the chemically strengthened glass below the antifouling layer was measured. Specifically, a water droplet of about 1 μL was placed on the surface of the chemically strengthened glass, and the water contact angle (°) was measured using a contact angle meter. Since the water contact angle on the surface of the antifouling layer is greater than the water contact angle on the chemically strengthened glass before the antifouling layer is formed, a larger water contact angle in the rubber rubbing test is thought to correspond to a larger amount of the formed antifouling layer remaining.

[0113] <Drop height> The drop strength of the obtained chemically strengthened glass of each example was evaluated by the following procedure. Each example of chemically strengthened glass was fitted into a structure whose mass and rigidity were adjusted to match the size of a typical smartphone currently in use, to create a pseudo-smartphone. The pseudo-smartphone was then free-falling onto #80 SiC sandpaper, with the side with the chemically strengthened glass facing the ground, while varying the height. The drop height was first 20 cm. If the chemically strengthened glass did not break after being dropped from a height of 20 cm, it was dropped from a height of 25 cm. If the chemically strengthened glass did not break after being dropped from a height of 25 cm, it was dropped from a height of 30 cm. If the glass did not break after being dropped, it was dropped from a height 5 cm higher than the previous height, and this process was repeated until the chemically strengthened glass broke. The height at which the chemically strengthened glass first broke in the above procedure was recorded as the drop height. The drop height was measured for each of the 19 tempered glass sheets, and the arithmetic mean value of the drop heights is shown in the table below as the drop height. Note that a larger drop height value corresponds to the chemically strengthened glass not breaking even when dropped from a higher position, i.e., the higher the drop strength.

[0114] <Result> The composition of the chemically strengthened glass subjected to the chemical strengthening treatment in each example, the conditions for the chemical strengthening treatment, and the results of the above measurements are shown in Tables 1 to 3 below. In Tables 2 and 3, the maximum measured voltages were measured using the method described above. Tables 2 and 3 show the absolute values ​​of the maximum measured voltages. In Table 2, Young's modulus and K IC The fracture toughness values ​​are values ​​measured by the above-mentioned method using a sample piece for measurement. In Table 2, the descriptions in the stress profile column have the following meanings. The calculation method for each value is as described above or as shown below. CS 50 and C.S. 90 : Compressive stress at each depth (unit: μm) of the obtained chemically strengthened glass CS0: Compressive stress on the surface of chemically strengthened glass DOC: Depth of compressive stress layer in chemically strengthened glass The above-mentioned "DOC" is typically the depth at which the compressive stress is 0 MPa in the stress distribution obtained using only a scattered light photoelastic stress meter. CS area : Product of compressive stress layer depth DOC of chemically strengthened glass and CS0 CT Max : Maximum tensile stress CT ave :Average value of tensile stress ICT: Average value of tensile stress

[0115] [Table 1]

[0116] [Table 2]

[0117] [Table 3]

[0118] From the results shown in Table 2, it was confirmed that the chemically strengthened glasses of Examples 4 to 12 were chemically strengthened glass-ceramics, and were novel glasses with maximum measured voltages of 1950 V or more. Comparison of Examples 4 to 8 with Examples 9 to 12 confirmed that when the maximum measured voltage was less than 2070 V, the antifouling layer formed on the surface of the chemically strengthened glass-ceramics had excellent durability. From the results shown in Table 3, it was confirmed that the chemically strengthened glasses of Examples 1 and 3 were glass-ceramics for chemical strengthening, and were novel glasses with a maximum measured voltage of 1200 V or more.

Claims

1. A chemically strengthened glass-ceramics obtained by chemically strengthening a chemically strengthened glass-ceramics, A chemically strengthened glass-ceramics is charged for 30 seconds using a static honestometer device to generate a corona discharge at an applied voltage of 10 kV, and the absolute value of the maximum measured voltage is 1950 V or more.

2. The composition of the glass-ceramics for chemical strengthening is expressed in mole percentage based on oxides, SiO ２ 60 to 75% of Al ２ O ３ を3~20%、 P ２ O ５ 0 to 5%, Li ２ Oを6~23%、 Na ２ Oを0~5%、 K ２ O 0 to 5%, MgO 0 to 10%, CaO 0 to 5%, ZrO ２ 2. The chemically strengthened glass-ceramics according to claim 1, containing 0 to 5% of

3. Li ３ P.O. ４ , Li ２ SiO ３ , Li ２ Si ２ O ５ , LiAlSi ４ O １０ , and LiAlSi ２ O ６ The chemically strengthened glass-ceramics according to claim 1 or 2, comprising crystals selected from the group consisting of:

4. 3. The chemically strengthened glass-ceramics according to claim 1, wherein the absolute value of the maximum measured voltage is 2250 V or less.

5. Fracture toughness value K ＩＣ However, 0.90 MPa m １／２ The chemically strengthened glass-ceramics according to claim 1 or 2, wherein

6. 3. The chemically strengthened glass-ceramics according to claim 1, having a Young's modulus of 85 GPa or more.

7. The average value CT of the tensile stress of the chemically strengthened crystallized glass ａｖｅ The chemically strengthened glass-ceramics according to claim 1 or 2, wherein the strain is 95 MPa or more.

8. The maximum value CT of the tensile stress of the chemically strengthened crystallized glass Ｍａｘ The chemically strengthened glass-ceramics according to claim 1 or 2, wherein the strain is 100 MPa or more.

9. The chemically strengthened glass-ceramics according to claim 1 or 2, which satisfies the following formula (I): Formula (I) CS ９０ ≧ 0.2t - 10 In formula (I), CS ９０ is the compressive stress value at a depth of 90 μm from the surface of the chemically strengthened crystallized glass, and is expressed in MPa. In formula (I), t is the thickness of the chemically strengthened crystallized glass, and is expressed in μm.

10. The chemically strengthened crystallized glass according to claim 1, wherein the compressive stress layer depth DOC is 0.17 to 0.25 times the plate thickness of the chemically strengthened crystallized glass, wherein the unit of the compressive stress layer depth and the unit of the plate thickness of the chemically strengthened crystallized glass are μm.

11. 3. The chemically strengthened crystallized glass according to claim 1, wherein an anti-fouling layer containing a fluorine-containing compound is formed on one side of the chemically strengthened crystallized glass, and after a rubber rubbing test is performed 2,500 times under a load of 9.8 N on the side of the chemically strengthened crystallized glass on which the anti-fouling layer is formed, the water contact angle is 80° or more.

12. A chemically strengthened crystallized glass having an absolute value of 1200 V or more of the maximum measured voltage when corona discharge is generated at an applied voltage of 10 kV using a static honestometer device and the glass is charged for 30 seconds.

13. In mole percentage based on oxides, SiO ２ 60 to 75% of Al ２ O ３ を3~20%、 P ２ O ５ 0 to 5%, Li ２ Oを6~23%、 Na ２ Oを0~5%、 K ２ O 0 to 5%, MgO 0 to 10%, CaO 0 to 5%, ZrO ２ The glass-ceramics for chemical strengthening according to claim 12, containing 0 to 5% of

14. Li ３ P.O. ４ , Li ２ SiO ３ , Li ２ Si ２ O ５ , LiAlSi ４ O １０ , and LiAlSi ２ O ６ The glass-ceramics for chemical strengthening according to claim 12 or 13, comprising crystals selected from the group consisting of:

15. Fracture toughness value K ＩＣ However, 0.90 MPa m １／２ The glass-ceramics for chemical strengthening according to claim 12 or 13, wherein the glass-ceramics is of the above structure.

16. 14. The chemically strengthened crystallized glass according to claim 12, having a Young's modulus of 85 GPa or more.

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