Chemically strengthened glass

Abstract

The present invention relates to a sheet-shaped chemically strengthened glass, wherein the chemically strengthened glass has a haze of 1.0% or less in terms of a thickness of 0.70 mm, and the ratio of the kurtosis value Rku of surface unevenness and the Vickers hardness Hv ((Rku / Hv) × 1000) is 1 to 4.4.

Description

[Technical Field]

[0001] The present invention relates to chemically strengthened glass. [Background technology]

[0002] BACKGROUND ART In recent years, cover glasses made of chemically strengthened glass have been used for the purpose of protecting display devices such as mobile phones, smartphones, and tablet terminals and improving their appearance.

[0003] Touch panels used in smartphones and other devices are required to be stain-resistant because they are easily stained by fingerprints and other contaminants, and are therefore required to be easy to operate with fingers. For example, Patent Document 1 describes the use of a fluorine-containing organosilicon compound as a coating that improves antifouling properties and finger slipperiness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2000-144097 Summary of the Invention [Problem to be solved by the invention]

[0005] However, coating films of fluorine-containing organosilicon compounds and the like may peel off, and there is a demand for improved adhesion between the cover glass and such coating films.

[0006] In view of the above circumstances, an object of the present invention is to provide chemically strengthened glass that has excellent film adhesion to a coating film. [Means for solving the problem]

[0007] The present inventors have discovered that forming appropriate irregularities on the glass surface is effective in preventing peeling of the coating film, and have arrived at the present invention.

[0008] That is, the present invention provides a plate-shaped chemically strengthened glass, The haze equivalent to a thickness of 0.70 mm is 1.0% or less, On at least one of the main surfaces, Provided is a chemically strengthened glass in which the ratio (Rku / Hv) × 1000 of the kurtosis Rku of the surface irregularities to the Vickers hardness Hv is 1 or more and 4.4 or less.

[0009] The chemically strengthened glass of the present invention is a plate-shaped chemically strengthened glass, On at least one of the main surfaces, Provided is chemically strengthened glass in which the height frequency distribution of surface irregularities is fitted with two or more normal distribution functions.

[0010] The chemically strengthened glass of the present invention is preferably glass-ceramic.

[0011] The chemically strengthened glass of the present invention preferably contains SiO2-Al2O3-Li2O crystals.

[0012] The chemically strengthened glass of the present invention is made of LiAlSi2O6, Li2Si2O5 and Al6O 13 It is preferable that the material contains one or more crystals selected from the group consisting of Si2.

[0013] The chemically strengthened glass of the present invention has a matrix composition expressed in mole percentage based on oxides, SiO2 40-80%, Al2O3 3-30%, P2O5 0-5%, B2O3 0-10% Li2O 5-40%, Na2O 0-10%, K2O 0-5%, MgO 0-5% CaO 0-5%, SrO 0-5%, BaO 0-5%, ZrO2 1-5%, SnO2 0-4%, It is preferable that Y2O3 is contained in an amount of 0 to 4%. [Effects of the Invention]

[0014] According to the present invention, the surface irregularities of the glass are appropriately controlled during glass formation, thereby obtaining chemically strengthened glass that has good film adhesion to a coating film. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing the height frequency distribution of the chemically strengthened glass of Example 1. [Figure 2] FIG. 2 is a diagram showing the height frequency distribution of the chemically strengthened glass of Example 2. [Figure 3] FIG. 3 shows the results of a peel resistance test of the antifouling layer for the chemically strengthened glasses of Examples 1 and 2. DETAILED DESCRIPTION OF THE INVENTION

[0016] In this specification, the use of "to" to indicate a range of values ​​means that the values ​​before and after it are included as the lower and upper limits. Unless otherwise specified, "to" will be used in the same sense hereinafter in this specification.

[0017] In this specification, "chemically strengthened glass" refers to glass after chemical strengthening treatment, and "glass for chemical strengthening" refers to glass before chemical strengthening treatment. In this specification, the "base composition of chemically strengthened glass" refers to the glass composition of glass for chemical strengthening. In chemically strengthened glass, the glass composition at a depth of half the plate thickness t is the same as the base composition of the chemically strengthened glass, except when extreme ion exchange treatment is performed.

[0018] In this specification, unless otherwise specified, glass compositions are expressed in terms of mole percentage on an oxide basis, and mole % is simply represented as "%". In addition, in this specification, "substantially free" means that the content is at or below the level of impurities contained in raw materials, etc., that is, that the content is not intentionally added. Specifically, for example, it is less than 0.1 mol %.

[0019] In this specification, the term "stress profile" refers to a representation of compressive stress values ​​with depth from the glass surface as a variable. The term "depth of compressive stress layer (DOL)" refers to the depth at which the compressive stress value (CS) is zero. The term "internal tensile stress value (CT)" refers to the tensile stress value at a depth of half the glass thickness t. In this specification, the tensile stress value is expressed as a negative compressive stress value.

[0020] The stress profile in this specification can be measured using a scattered light photoelastic stress meter (e.g., the SLP-1000 manufactured by Orihara Manufacturing Co., Ltd.). The scattered light photoelastic stress meter may be affected by surface scattering, which can reduce the measurement accuracy near the sample surface. However, for example, if compressive stress is generated solely by ion exchange between lithium ions in the glass and external sodium ions, the compressive stress value expressed as a function of depth follows a complementary error function, so measuring the internal stress value allows the surface stress value to be determined. In cases where the compressive stress value expressed as a function of depth does not follow a complementary error function, the surface portion can be measured using a different method (e.g., a surface stress meter).

[0021] <Chemically strengthened glass> The chemically strengthened glass of the present invention (hereinafter also referred to as "the present chemically strengthened glass") is preferably plate-shaped. That is, the present chemically strengthened glass preferably has a first main surface, an opposing second main surface, and edges contacting each of the first and second main surfaces. The present chemically strengthened glass is, for example, flat with the first and second main surfaces parallel to each other, but the first and second main surfaces do not have to be parallel, and one or both main surfaces may be partially or entirely curved. The present chemically strengthened glass has a haze of 1.0% or less, and on at least one main surface, the ratio (Rku / Hv) × 1000 of the kurtosis Rku of the surface irregularities to the Vickers hardness Hv is 1 or more and 4.4 or less.

[0022] The thickness (t) of the chemically strengthened glass is, for example, 2 mm or less, preferably 1.5 mm or less, more preferably 1 mm or less, even more preferably 0.9 mm or less, particularly preferably 0.8 mm or less, and most preferably 0.7 mm or less. In order to obtain sufficient strength, the thickness is, for example, 0.1 mm or more, preferably 0.2 mm or more, more preferably 0.4 mm or more, even more preferably 0.5 mm or more, and particularly preferably 0.6 mm or more.

[0023] In this chemically strengthened glass, the kurtosis Rku of the surface irregularities represents the sharpness of the height frequency distribution of the irregularities on the glass surface. When Rku = 3, the surface irregularities exhibit a normal distribution, when Rku < 3, the height frequency distribution of the surface irregularities appears flat, and when Rku > 3, the height distribution appears sharp.

[0024] It is known that when glass is polished under the same conditions, there is a correlation between the hardness of the glass and the roughness of the glass surface after polishing. Therefore, the surface roughness of this chemically strengthened glass can be evaluated by Rku per unit hardness.

[0025] That is, on at least one principal surface of the chemically strengthened glass, the ratio (Rku / Hv) × 1000 of the kurtosis Rku of the surface irregularities to the Vickers hardness Hv is 1 or more and 4.4 or less. When (Rku / Hv) × 1000 is 4.4 or less, Rku is relatively small relative to the hardness of the glass, preventing excessively sharp shapes. If the height frequency distribution is somewhat flat, the frequency bias of the surface irregularities to specific heights is relatively small. This results in relatively few flat regions in the surface irregularities, making the surface irregularities more likely to include multiple patterns of irregular shapes or irregular shapes, and less likely to be composed solely of repetitions of specific irregular shapes. The chemically strengthened glass has such surface irregularities, which can increase the surface area of ​​the glass surface and provide excellent film adhesion to coating films. (Rku / Hv) × 1000 is more preferably 4 or less, even more preferably 3.8 or less, and particularly preferably 3.6 or less.

[0026] From a similar perspective, (Rku / Hv) × 1000 is 1 or greater. If the height frequency distribution is too flat, the surface unevenness tends to have an excessively small frequency bias toward a specific height. In this case, various degrees of unevenness are included, such as a large undulation with minute unevenness, which tends to increase the flat areas in the surface unevenness and reduce the surface area of ​​the glass surface. By making (Rku / Hv) × 1000 1 or greater, the surface unevenness tends to include multiple patterns of uneven shapes or irregular uneven shapes, as described above, thereby increasing the surface area. (Rku / Hv) × 1000 is more preferably 1.5 or greater, even more preferably 2 or greater, and particularly preferably 2.5 or greater.

[0027] Furthermore, it is preferable that the height frequency distribution of the surface irregularities on at least one main surface of the chemically strengthened glass be fitted with two or more normal distribution functions. Figure 1 is a diagram showing the height frequency distribution of the chemically strengthened glass of Example 1 in the Examples, and is an example where the height frequency distribution is fitted with two normal distribution functions. Figure 2 is a diagram showing the height frequency distribution of the chemically strengthened glass of Example 2, and is an example where the height frequency distribution is fitted with one normal distribution function.

[0028] In other words, fitting the height frequency distribution of the surface irregularities with two or more normal distribution functions tends to increase the variability of the height frequency distribution compared to fitting the height frequency distribution of the surface irregularities with one normal distribution function, and tends to appropriately reduce the frequency bias toward specific heights in the surface irregularities. This is thought to facilitate improved film adhesion of the present chemically strengthened glass.

[0029] From the viewpoint of improving film adhesion, Rku in the present chemically strengthened glass is preferably 4.4 or less, more preferably 4 or less, even more preferably 3.8 or less, and particularly preferably 3.6 or less. From the viewpoint of improving film adhesion, the lower limit of Rku is also preferably 1.0 or more, more preferably 1.5 or more, even more preferably 2.0 or more, and particularly preferably 2.5 or more. Rku can be calculated in accordance with JIS B0601 (2001) by measuring the surface roughness using, for example, an atomic force microscope (AFM).

[0030] The arithmetic mean roughness Ra of the chemically strengthened glass is preferably 0.05 nm or more, more preferably 0.1 nm or more, from the viewpoint of improving film adhesion. Furthermore, from the viewpoint of aesthetic appearance, Ra is preferably 10 nm or less, more preferably 5 nm or less, and even more preferably 1 nm or less. The arithmetic mean roughness Ra can be measured in accordance with JIS B0601 (2001).

[0031] The chemically strengthened glass has excellent film adhesion, which means that the antifouling layer has excellent peel resistance as measured by the following method. The peel resistance of the antifouling layer can be evaluated by forming the antifouling layer on the glass surface, subjecting it to "eraser friction abrasion," and then measuring the contact angle of a water droplet. The larger the water contact angle after eraser friction, the better the function of the antifouling layer is maintained and the better the peel resistance.

[0032] Specifically, the peel resistance of the stain-resistant layer can be evaluated by, for example, measuring the contact angle of a water droplet after subjecting the layer to friction and abrasion with an eraser in the following manner. (eraser friction wear) A cylindrical eraser with a diameter of 6 mm is attached to an abrasion tester, and the surface of the antifouling layer is abraded 7,500 times under the conditions of a load of 1 kgf, a stroke width of 40 mm, a speed of 40 rpm, and an ambient temperature of 25°C and 50% RH. (Water contact angle measurement) A droplet of about 1 μL of pure water is placed on the surface after the eraser abrasion, and the contact angle with water is measured using a contact angle meter. The larger the water contact angle after abrasion, the better the durability of the antifouling layer. Specifically, for example, the difference between the water contact angle before abrasion and the water contact angle after abrasion is preferably 60° or less, more preferably 50° or less, and even more preferably 40° or less.

[0033] (Chemical strengthening properties) The chemically strengthened glass preferably has a surface compressive stress value CSO of 400 MPa or more, more preferably 450 MPa or more, even more preferably 500 MPa or more, still more preferably 550 MPa or more, particularly preferably 600 MPa or more, still more particularly preferably 700 MPa or more, and most preferably 800 MPa or more.

[0034] The greater the surface compressive stress value, the higher the strength; however, if the surface compressive stress value is too high, a large tensile stress will be generated inside the chemically strengthened glass, which may lead to fracture, so the surface compressive stress is preferably 1200 MPa or less, more preferably 1100 MPa or less.

[0035] In the stress profile of this chemically strengthened glass, the compressive stress value CS at a depth of 50 μm from the surface 50is preferably 50 MPa or more, more preferably 100 MPa or more, further preferably 150 MPa or more, and particularly preferably 200 MPa or more. 50 The large size makes chemically strengthened glass less likely to break when damaged by being dropped, etc.

[0036] The internal tensile stress value CT of the chemically strengthened glass is preferably 150 MPa or less, more preferably 130 MPa or less, and even more preferably 100 MPa or less. A small CT makes it less likely to fracture. The internal tensile stress value CT is preferably 50 MPa or more, more preferably 60 MPa or more, and even more preferably 70 MPa or more. A CT of at least the above value increases the compressive stress near the surface, resulting in increased strength.

[0037] If the compressive stress layer depth DOL of the chemically strengthened glass is too large relative to the thickness t, it will result in an increase in CT, so it is preferably 0.2t or less, more preferably 0.19t or less, and even more preferably 0.18t or less. Furthermore, from the viewpoint of improving strength, DOL is preferably 0.06t or more, more preferably 0.08t or more, even more preferably 0.10t or more, and particularly preferably 0.12t or more. Specifically, for example, DOL is preferably 180 μm or less, more preferably 160 μm or less. Furthermore, DOL is preferably 60 μm or more, more preferably 80 μm or more, and even more preferably 100 μm or more.

[0038] The present chemically strengthened glass is preferably glass-ceramic, which is preferable because the present chemically strengthened glass is likely to have high hardness, improved fracture toughness, and less susceptible to scratch extension.

[0039] The chemically strengthened glass preferably contains one or more of lithium silicate crystals, lithium aluminosilicate crystals, aluminosilicate crystals, and lithium phosphate crystals. From the viewpoint of improving the chemical strengthening properties, i.e., improving the strength of the chemically strengthened glass, it is more preferable that the glass contains lithium aluminosilicate crystals, i.e., SiO2-Al2O3-Li2O-based crystals.

[0040] As the lithium aluminosilicate crystal, for example, petalite crystal, β-spodumene crystal (LiAlSi2O6) or β-quartz solid solution is preferable. As the lithium silicate crystal, for example, lithium metasilicate crystal or lithium disilicate crystal (Li2Si2O5) is preferable. As the lithium phosphate crystal, for example, lithium orthophosphate crystal is preferable. As the aluminosilicate crystal, for example, mullite (Al6O 13 Si2) is preferred.

[0041] Glass-ceramics are obtained by heat-treating amorphous glass to crystallize it. The glass composition of glass-ceramics is the same as that of amorphous glass.

[0042] The visible light transmittance of this chemically strengthened glass (total visible light transmittance including diffuse transmitted light) is preferably 85% or more when converted to a thickness of 0.70 mm, so that when used as a cover glass for a mobile display, the display screen is easy to see. A visible light transmittance of 88% or more is more preferable, and 90% or more is even more preferable. The higher the visible light transmittance, the better, but it is usually 93% or less. Note that the visible light transmittance of ordinary amorphous glass is about 90% or more. If the thickness of the glass-ceramic is not 0.70 mm, the transmittance for a thickness of 0.70 mm can be calculated from the measured transmittance using the Lambert-Beer law. If the total visible light transmittance of the glass with thickness t [mm] is 100 × T [%] and the surface reflectance of one side is 100 × R [%], then by applying the Lambert-Beer law and using the constant α, T = (1 - R) 2 ×exp(-αt). From here, if α is expressed in terms of R, T, and t, and t = 0.70 mm, R does not change depending on the plate thickness, so the total light visible light transmittance T 0.7 is T 0.7 =100×T 0.7 / t / (1-R)^(1.4 / t-2)[%], where X^Y is X Y Represents. The surface reflectance may be calculated from the refractive index or may be actually measured. Furthermore, for glass with a thickness t greater than 0.70 mm, the thickness may be adjusted to 0.70 mm by polishing, etching, etc., and then actual measurements may be performed. Note that the visible light transmittance of chemically strengthened glass is roughly the same before and after chemical strengthening, and the transmittance does not change significantly even if the ion-exchanged layer on the surface is removed by polishing, etc.

[0043] Furthermore, the haze value of this chemically strengthened glass, converted into a thickness of 0.70 mm, is 1.0% or less. With a haze value of 1.0% or less, when used as the cover glass of a mobile display, for example, the display screen is easy to see. The haze value is preferably 0.4% or less, more preferably 0.3% or less, even more preferably 0.2% or less, and particularly preferably 0.15% or less. The smaller the haze value, the better, but if the crystallization rate or the crystal grain size is reduced to reduce the haze value, the mechanical strength will decrease. To increase the mechanical strength, the haze value for a thickness of 0.70 mm is preferably 0.02% or more, more preferably 0.03% or more. The haze value is measured according to JIS K7136 (2000).

[0044] If the total visible light transmittance of crystallized glass with a thickness of t [mm] is 100×T [%] and the haze value is 100×H [%], then by applying the Beer-Lambert law and using the constant α mentioned above, dH / dt ∝ exp(-αt) × (1-H) This can be expressed as: In other words, the haze value is thought to increase in proportion to the internal linear transmittance as the plate thickness increases, so the haze value H for 0.70 mm is 0.7 can be calculated using the following formula. However, "X^Y" is "X Y " represents. H 0.7 =100×[1-(1-H)^{((1-R) 2 -T 0.7 ) / ((1-R) 2 -T)}][%] In addition, in the case of glass having a thickness t of more than 0.70 mm, the thickness may be adjusted to 0.70 mm by polishing or etching, and then the actual measurement may be performed.

[0045] When this chemically strengthened glass is used as the cover glass for a mobile display, it is preferable that it has a texture and a luxurious feel different from plastic. Therefore, the refractive index of this chemically strengthened glass at a wavelength of 590 nm is preferably 1.52 or more, more preferably 1.55 or more, and even more preferably 1.57 or more.

[0046] When the chemically strengthened glass is a crystallized glass, the crystallization rate is preferably 5% or more, more preferably 10% or more, even more preferably 15% or more, and particularly preferably 20% or more to increase the mechanical strength. To increase transparency, the crystallization rate is preferably 70% or less, more preferably 60% or less, and particularly preferably 50% or less. A small crystallization rate is also advantageous in that it is easy to heat and bend.

[0047] The crystallinity can be calculated from the X-ray diffraction intensity by the Rietveld method. The Rietveld method is described in "Crystal Analysis Handbook" (Kyoritsu Shuppan, 1999, pp. 492-499), edited by the Editorial Committee of the Crystallographic Society of Japan.

[0048] The average particle size of the precipitated crystals of the crystallized glass is preferably 80 nm or less, more preferably 60 nm or less, even more preferably 50 nm or less, particularly preferably 40 nm or less, and most preferably 30 nm or less. The average particle size of the precipitated crystals can be determined from a transmission electron microscope (TEM) image. The average particle size of the precipitated crystals can be estimated from a scanning electron microscope (SEM) image.

[0049] The average thermal expansion coefficient of this chemically strengthened glass between 50℃ and 350℃ is 90×10 -7 / °C or more, and more preferably 100 × 10 -7 / °C or higher, more preferably 110 × 10 -7 / °C or more, particularly preferably 120 × 10 -7 / °C or higher, most preferably 130 × 10 -7 / ℃ or more.

[0050] If the thermal expansion coefficient is too large, cracks may occur during the chemical strengthening process due to the difference in the thermal expansion coefficient. Therefore, the thermal expansion coefficient is preferably 160 × 10 ―7 / ℃ or less, more preferably 150×10 -7 / °C or less, more preferably 140 × 10 -7 / ℃ or less.

[0051] In order to increase the wear resistance of the chemically strengthened glass, the Vickers hardness Hv is preferably 600 or more, more preferably 700 or more, even more preferably 730 or more, particularly preferably 750 or more, and most preferably 780 or more. If the chemically strengthened glass is crystallized glass, it contains crystals, so the hardness tends to be high. Therefore, it is resistant to scratches and tends to have excellent wear resistance.

[0052] If the hardness is too high, processing becomes difficult, so the Vickers hardness Hv of the present chemically strengthened glass is preferably 1100 or less, more preferably 1050 or less, and even more preferably 1000 or less. In this specification, the Vickers hardness Hv refers to the Vickers hardness (Hv0.1) defined in JIS R1610:2003.

[0053] The high Young's modulus of the chemically strengthened glass means that the bonding strength of the elements constituting the glass is high, and that a large force is required to break the glass. The Young's modulus is preferably 85 GPa or more, more preferably 90 GPa or more, even more preferably 95 GPa or more, and particularly preferably 100 GPa or more. In addition, from the viewpoint of suppressing the increase in tensile stress at the same deflection amount and the tendency to break, the Young's modulus is preferably 130 GPa or less, more preferably 125 GPa or less, and even more preferably 120 GPa or less.

[0054] The fracture toughness value of the chemically strengthened glass is preferably 0.8 MPa m 1 / 2 More preferably, 0.85 MPa m1 / 2 More preferably, 0.9 MPa m 1 / 2 This is preferable because fragments are less likely to fly off when broken.

[0055] (composition) The present chemically strengthened glass is preferably lithium aluminosilicate glass. That is, the glass for chemical strengthening used in the present chemically strengthened glass is preferably lithium aluminosilicate glass.

[0056] Specifically, the base composition of the chemically strengthened glass preferably contains 40% or more of SiO2, 3% or more of Al2O3, and 5% or more of Li2O. Because lithium aluminosilicate glass contains lithium ions, which are alkali ions with the smallest ionic radius, chemically strengthened glass with a desirable stress profile can be obtained by chemical strengthening treatment using ion exchange with various molten salts.

[0057] The base composition of this chemically strengthened glass is expressed as mole percentage based on oxides: SiO2 40-80%, Al2O3 3-30%, P2O5 0-5%, B2O3 0-10% Li2O 5-40%, Na2O 0-10%, K2O 0-5%, MgO 0-5% CaO 0-5%, SrO 0-5%, BaO 0-5%, ZrO2 1-5%, SnO2 0-4%, It is more preferable that Y2O3 is contained in an amount of 0 to 4%. In addition, in the case of chemically strengthened glass, except in cases where extreme ion exchange treatment has been performed, the glass composition at a depth of 1 / 2 of the plate thickness t is the same as the base composition of the chemically strengthened glass. The glass composition will be explained below.

[0058] SiO2 is a component that makes up the network of glass. SiO2 also increases chemical durability and reduces the occurrence of cracks when the glass surface is scratched. To improve chemical durability, the SiO content is preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, even more preferably 55% or more, and particularly preferably 60% or more. To improve meltability during glass production, the SiO content is preferably 80% or less, more preferably 75% or less, even more preferably 72% or less, and particularly preferably 70% or less.

[0059] Al2O3 is an effective component from the viewpoint of improving the ion exchange performance during chemical strengthening and increasing the surface compressive stress after strengthening. The Al2O3 content is preferably 1% or more, more preferably 3% or more, even more preferably 4% or more, and particularly preferably 5% or more, in order to improve chemical durability and chemical strengthening properties. On the other hand, if the Al2O3 content is too high, crystals may easily grow during melting. In order to prevent a decrease in yield due to devitrification defects and to reduce the haze value of the crystallized glass, the Al2O3 content is preferably 30% or less, more preferably 20% or less, even more preferably 15% or less, and particularly preferably 10% or less.

[0060] Both SiO2 and Al2O3 are components that stabilize the structure of glass, and in order to reduce brittleness, the total content is preferably 43% or more, more preferably 50% or more, even more preferably 55% or more, and particularly preferably 60% or more. Both SiO2 and Al2O3 tend to increase the melting temperature of the glass, and therefore, in order to facilitate melting, their total content is preferably 95% or less, more preferably 90% or less, even more preferably 87% or less, even more preferably 85% or less, and particularly preferably 82% or less.

[0061] Li2O is a component that forms surface compressive stress through ion exchange and improves the meltability of glass. By including Li2O in chemically strengthened glass, Li ions on the glass surface are ion-exchanged with Na ions, and then the Na ions are further ion-exchanged with K ions, resulting in a large stress profile for both the surface compressive stress and the compressive stress layer.

[0062] In order to increase the surface compressive stress during chemical strengthening, the Li2O content is preferably 5% or more, more preferably 7% or more, even more preferably 10% or more, and particularly preferably 15% or more. On the other hand, if the Li2O content is too high, the crystal growth rate during glass molding increases, which can lead to a serious problem of reduced yield due to devitrification defects. To suppress devitrification during the glass production process, the Li2O content is preferably 40% or less, more preferably 35% or less, even more preferably 30% or less, still more preferably 25% or less, particularly preferably 22% or less, and most preferably 18% or less.

[0063] Although neither Na2O nor K2O is essential, they are components that improve the meltability of the glass and reduce the crystal growth rate of the glass, and are preferably contained in order to improve the ion exchange performance.

[0064] Na2O is a component that forms a surface compressive stress layer in chemical strengthening treatment using potassium salts and can also improve the meltability of glass. To achieve this effect, the Na2O content is preferably 1% or more, more preferably 2% or more, even more preferably 3% or more, and even more preferably 3.5% or more. On the other hand, if the Na2O content is too high, it becomes difficult to increase the compressive stress in a relatively deep portion from the surface by chemical strengthening, so the content is preferably 10% or less, more preferably 8% or less, even more preferably 5% or less, and particularly preferably 3% or less.

[0065] K2O may be contained for the purpose of suppressing devitrification during the glass manufacturing process. When K2O is contained, the content is preferably 0.1% or more, more preferably 0.15% or more, and particularly preferably 0.2% or more. To further prevent devitrification, the content is preferably 0.5% or more, and more preferably 1.2% or more. On the other hand, since a large amount of K can cause brittleness and a decrease in surface stress due to back-exchange during tempering, the content of K2O is preferably 5% or less, more preferably 3% or less, even more preferably 2% or less, even more preferably 1% or less, and particularly preferably 0.5% or less.

[0066] The total content of Na2O and K2O ([Na2O] + [K2O]) is preferably 3% or more, more preferably 3.5% or more, even more preferably 4% or more, and particularly preferably 4.5% or more in order to improve the meltability of the glass. If ([Na2O] + [K2O]) is too high, the surface compressive stress value is likely to decrease, so ([Na2O] + [K2O]) is preferably 15% or less, more preferably 10% or less, even more preferably 8% or less, and particularly preferably 6% or less.

[0067] Although MgO is not essential, it may be contained to reduce viscosity during dissolution, etc. When MgO is contained, the content is preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more. On the other hand, if the MgO content is too high, it becomes difficult to increase the compressive stress layer during chemical strengthening treatment. The MgO content is preferably 5% or less, more preferably 4% or less, even more preferably 3% or less, and particularly preferably 2% or less.

[0068] Although CaO is not essential, it is a component that improves the meltability of glass and may be contained. When CaO is contained, the content is preferably 0.1% or more, more preferably 0.15% or more, and even more preferably 0.5% or more. On the other hand, if the CaO content is excessive, it becomes difficult to increase the compressive stress value during chemical strengthening treatment. The CaO content is preferably 5% or less, more preferably 3% or less, even more preferably 1% or less, and typically 0.5% or less.

[0069] Although not essential, SrO is a component that improves the meltability of chemically strengthened glass and also improves the refractive index of the glass. SrO may be contained because it can improve the transmittance of the crystallized glass by bringing the refractive index of the glass phase remaining after crystallization closer to the refractive index of the precipitated crystals. When SrO is contained, the content is preferably 0.1% or more, more preferably 0.2% or more, even more preferably 0.5% or more, and particularly preferably 1% or more. On the other hand, if the SrO content is too high, the ion exchange rate decreases, so it is preferably 5% or less, more preferably 2.5% or less, and even more preferably 1.8% or less.

[0070] Although not essential, BaO is a component that improves the meltability of the glass for chemical strengthening and also improves the refractive index of the glass. BaO may be contained because it can improve the transmittance of the crystallized glass by bringing the refractive index of the glass phase remaining after crystallization closer to the refractive index of the precipitated crystals. When BaO is contained, the content is preferably 0.1% or more, more preferably 0.2% or more, even more preferably 0.5% or more, and particularly preferably 1% or more. On the other hand, if the BaO content is too high, the ion exchange rate decreases, so the content is preferably 5% or less, more preferably 2% or less, and even more preferably 1.5% or less.

[0071] ZnO is a component that improves the meltability of glass and also improves the refractive index of glass. ZnO may be contained because it can improve the transmittance of crystallized glass by bringing the refractive index of the glass phase remaining after crystallization closer to that of the precipitated crystals. When ZnO is contained, the content is preferably 0.2% or more, more preferably 0.5% or more. To improve the weather resistance of the glass, the ZnO content is preferably 8% or less, more preferably 5% or less, and even more preferably 3% or less.

[0072] ZnO, SrO, and BaO tend to deteriorate chemical strengthening properties, so in order to facilitate chemical strengthening, the total content of ZnO, SrO, and BaO ([ZnO] + [SrO] + [BaO]) is preferably less than 1%, more preferably 0.5% or less, and even more preferably substantially none of these is contained.

[0073] Although ZrO2 does not have to be contained, it is preferable to contain it from the viewpoint of increasing the surface compressive stress of chemically strengthened glass. Furthermore, ZrO2 is a component that can form crystal nuclei during crystallization treatment. The ZrO2 content is preferably 0.5% or more, more preferably 1.0% or more, and even more preferably 2% or more. On the other hand, if the ZrO2 content is too high, devitrification defects are likely to occur, making it difficult to increase the compressive stress value during chemical strengthening treatment. The ZrO2 content is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0074] To increase the fracture toughness, it is preferable to contain at least one of Y2O3, La2O3, and ZrO2 in a total amount of 0.2% or more. The total content of Y2O3, La2O3, and ZrO2 is preferably 0.5% or more, more preferably 1.0% or more, and even more preferably 1.5% or more. Furthermore, to lower the liquidus temperature and suppress devitrification, the total content of these elements is preferably 6% or less, more preferably 5% or less, and even more preferably 4% or less.

[0075] In order to lower the devitrification temperature and suppress devitrification, the total content of Y2O3 and La2O3 is preferably greater than the content of ZrO2, and the content of Y2O3 is more preferably greater than the content of ZrO2.

[0076] Although Y2O3 is not essential, it is preferable to include it in order to increase the surface compressive stress of chemically strengthened glass while reducing the crystal growth rate. The Y2O3 content is preferably 0.1% or more, more preferably 0.2% or more, even more preferably 0.5% or more, and particularly preferably 1% or more. On the other hand, if the Y2O3 content is too high, it becomes difficult to increase the compressive stress layer during chemical strengthening treatment. The Y2O3 content is preferably 10% or less, more preferably 5% or less, even more preferably 4% or less, even more preferably 3% or less, particularly preferably 2% or less, and even particularly preferably 1.5% or less.

[0077] La2O3 is not essential, but can be included 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 content is preferably 5% or less, more preferably 3% or less, even more preferably 2% or less, and particularly preferably 1.5% or less.

[0078] Although not essential, TiO2 is a component that suppresses solarization of glass and may be contained. TiO2 is also a component that can form crystal nuclei during crystallization treatment. When TiO2 is contained, the content is preferably 0.02% or more, more preferably 0.03% or more, even more preferably 0.04% or more, particularly preferably 0.05% or more, and typically 0.06% or more. On the other hand, if the TiO2 content exceeds 2%, devitrification is likely to occur, and the quality of the chemically strengthened glass may deteriorate. The TiO2 content is preferably 2% or less, more preferably 1% or less, even more preferably 0.5% or less, and even more preferably 0.25% or less.

[0079] Although B2O3 is not essential, it may be contained for the purpose of reducing the brittleness of the glass and improving crack resistance, or for the purpose of improving the meltability of the glass. When B2O3 is contained, the content is preferably 0.5% or more, preferably 1% or more, and more preferably 2% or more. On the other hand, if the B2O3 content is too high, acid resistance tends to deteriorate, so the B2O3 content is preferably 10% or less. The B2O3 content is more preferably 6% or less, even more preferably 4% or less, and particularly preferably 2% or less. From the viewpoint of preventing the problem of striae formation during melting, it is more preferable that B2O3 is substantially not contained.

[0080] P2O5 is not essential, but may be contained for the purpose of increasing the compressive stress layer during chemical strengthening. When P2O5 is contained, the content is preferably 0.5% or more, preferably 1% or more, and more preferably 2% or more. On the other hand, from the viewpoint of increasing acid resistance, the content of P2O5 is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less. From the viewpoint of preventing the occurrence of striae during melting, it is more preferable that P2O5 is substantially not contained.

[0081] The total content of B2O3 and P2O5 is preferably 0 to 10%, more preferably 1% or more, and even more preferably 2% or more. The total content of B2O3 and P2O5 is more preferably 6% or less, and even more preferably 4% or less.

[0082] SnO2 has the effect of promoting the formation of crystal nuclei and may be contained. SnO2 is not essential, but when contained, it is preferably 0.5% or more, more preferably 1% or more, even more preferably 1.5% or more, and particularly preferably 2% or more. On the other hand, in order to suppress devitrification during melting, the content of SnO2 is preferably 4% or less, more preferably 3% or less, and even more preferably 2% or less.

[0083] NbO 5、 Ta2O5, Gd2O3 and CeO2 are not essential components, but they are components that suppress solarization of the glass and improve meltability. 5、One or more selected from Ta2O5, Gd2O3, and CeO2 may be contained. When these components are contained, the total content 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 typically 1% or more. On the other hand, if the total content of these components is too high, it becomes difficult to increase the compressive stress value during chemical strengthening treatment, so it is preferably 3% or less, more preferably 2% or less, even more preferably 1% or less, and particularly preferably 0.5% or less.

[0084] Fe2O3 absorbs heat rays and thus improves the meltability of glass, making it preferable to add it when mass-producing glass using a large melting furnace. In this case, the content is preferably 0.002% or more, more preferably 0.005% or more, even more preferably 0.007% or more, and particularly preferably 0.01% or more, by weight percent based on the oxide. On the other hand, excessive Fe2O3 content causes coloration, so from the viewpoint of improving the transparency of the glass, the 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, by weight percent based on the oxide.

[0085] Although all iron oxides in glass have been described as Fe2O3, in reality, a mixture of oxidized Fe(III) and reduced Fe(II) is usually present. Of these, Fe(III) produces a yellow color, while Fe(II) produces a blue color, and the balance between the two produces a green color in the glass.

[0086] Furthermore, coloring components may be added within a range that does not impede the achievement of the desired chemical strengthening properties. Suitable examples of coloring components include Co3O4, MnO2, NiO, CuO, Cr2O3, V2O5, Bi2O3, SeO2, CeO2, Er2O3, and Nd2O3.

[0087] The total content of the coloring components, expressed as mole percentage on an oxide basis, is preferably 5% or less. If it exceeds 5%, the glass may be prone to devitrification. The content of the coloring components is preferably 3% or less, and more preferably 1% or less. If high transmittance of the glass is desired, it is preferable that these components are substantially not contained.

[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.

[0089] <Method of manufacturing chemically strengthened glass> The chemically strengthened glass of the present invention is obtained by chemically strengthening a glass for chemical strengthening. When the chemically strengthened glass is a crystallized glass, the glass for chemical strengthening is obtained by heat-treating an amorphous glass to obtain a crystallized glass for chemical strengthening, and the obtained crystallized glass is then chemically strengthened.

[0090] (Manufacturing of chemically strengthened glass) The glass for chemical strengthening can be produced, for example, by the following method.

[0091] Glass raw materials are blended to obtain glass of a desired composition, and then heated and melted in a glass melting furnace. The molten glass is then homogenized by bubbling, stirring, adding a fining agent, etc., and formed into a glass plate of a predetermined thickness by a known forming method, and slowly cooled. Alternatively, the molten glass may be formed into a block, slowly cooled, and then cut into a plate.

[0092] Examples of forming methods for plate glass include the float method, the press method, the fusion method, and the down-draw method. In particular, when producing a large glass plate, the float method is preferred. In addition, continuous forming methods other than the float method, such as the fusion method and the down-draw method, are also preferred.

[0093] (crystallization treatment) When the glass for chemical strengthening is crystallized glass, the glass obtained by the above procedure is subjected to a heat treatment to obtain crystallized glass. The crystallization treatment may be performed after a polishing treatment or the like, which will be described later.

[0094] The heat treatment is preferably a two- or three-stage heat treatment in which the temperature is raised from room temperature to a first treatment temperature and maintained for a certain period of time, and then maintained at a second treatment temperature higher than the first treatment temperature for a certain period of time.

[0095] In the case of a two-stage heat treatment, the first treatment temperature is preferably in a temperature range where the crystal nucleation rate is high in the glass composition, and the second treatment temperature is preferably in a temperature range where the crystal growth rate is high in the glass composition. Furthermore, it is preferable to maintain the first treatment temperature for a long time so that a sufficient number of crystal nuclei are generated. By generating a large number of crystal nuclei, the size of each crystal becomes small, resulting in a highly transparent crystallized glass. Furthermore, when obtaining two-crystal crystallized glass, it may be preferable to increase the holding time of the heat treatment accordingly.

[0096] The first treatment temperature is, for example, 450°C to 700°C, and the second treatment temperature is, for example, 600°C to 800°C. After being held at the first treatment temperature for 1 to 6 hours, the second treatment temperature is held for 1 to 6 hours.

[0097] (Polishing process) The glass or glass-ceramics obtained by the above procedure is ground and polished as necessary to form glass for chemical strengthening. The uneven shape of this chemically strengthened glass can be controlled by adjusting the polishing conditions of the glass for chemical strengthening. That is, the polishing method for the glass for chemical strengthening may be any method that can obtain an uneven shape in which (Rku / Hv) × 1000 is 1 or more and 4.4 or less after chemical strengthening.

[0098] Specific polishing conditions that yield (Rku / Hv) × 1000 of 1 or greater and 4.4 or less can be adjusted appropriately to suit the glass being polished. To control surface roughness, it is preferable to adjust, for example, the average particle size of the polishing abrasive grains or the material of the polishing pad. For example, the average particle size of the polishing abrasive grains is preferably 500 nm or greater, more preferably 800 nm or greater, from the viewpoint of obtaining an appropriate Rku. Furthermore, the average particle size is preferably 3000 nm or less, more preferably 2000 nm or less, from the viewpoint of obtaining a beautiful mirror surface. Here, the average particle size refers to the median diameter measured based on the volume distribution using a laser diffraction / scattering method.

[0099] For example, a preferred method is to mix two or more types of abrasive grains to control the surface irregularities.

[0100] The type of polishing pad is not particularly limited, but a pad made of nonwoven fabric, for example, that can adequately hold polishing particles is preferred.

[0101] Furthermore, it is also preferable to perform polishing in two or more stages under multiple conditions, such as using different pads. An example of polishing in two or more stages is, for example, polishing in the first stage under conditions similar to those of a general polishing process, and polishing in the second stage using a pad different from that in the first stage for a short time to obtain the desired uneven shape.

[0102] It is known that when polishing glass under the same conditions, there is a correlation between the hardness of the glass and the roughness of the glass surface after polishing. Therefore, glasses with different hardness tend to have different surface roughness even when polished under the same conditions.

[0103] After polishing to obtain the desired uneven shape, the glass is washed and dried to obtain glass for chemical strengthening.

[0104] When cutting chemically strengthened glass into a predetermined shape and size or performing chamfering, if the cutting or chamfering is performed before performing the chemical strengthening treatment, a compressive stress layer is also formed on the end surface by the subsequent chemical strengthening treatment. This is preferable.

[0105] (chemical strengthening treatment) The present chemically strengthened glass can be obtained by chemically strengthening the glass for chemical strengthening obtained by the above method.

[0106] The chemical strengthening treatment can be performed by a known method. In the chemical strengthening treatment, a glass sheet is brought into contact with a melt of a metal salt (e.g., potassium nitrate) containing a metal ion with a large ionic radius by immersion or the like. This replaces the metal ions with a small ionic radius in the glass sheet with metal ions with a large ionic radius. Here, the metal ions with a small ionic radius are typically Na ions or Li ions. The metal ions with a large ionic radius are typically K ions or Na ions, specifically, K ions for Na ions and Na ions or K ions for Li ions.

[0107] The chemical strengthening treatment (ion exchange treatment) can be carried out, for example, by immersing the glass plate for 0.1 to 500 hours in a molten salt such as potassium nitrate heated to 360 to 600° C. The heating temperature of the molten salt is preferably 375 to 500° C., and the immersion time of the glass plate in the molten salt is preferably 0.3 to 200 hours.

[0108] Examples of molten salts used in chemical strengthening 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 molten salts may be used alone or in combination.

[0109] In the present invention, the treatment conditions for the chemical strengthening treatment may be appropriately selected in consideration of the properties and composition of the glass, the type of molten salt, and the chemical strengthening properties desired for the final chemically strengthened glass, such as the surface compressive stress and the depth of the compressive stress layer.

[0110] In the present invention, the chemical strengthening treatment may be performed only once, or multiple times under two or more different conditions (multi-stage strengthening). Here, for example, the first stage of chemical strengthening treatment is performed under conditions that increase the DOL and relatively decrease the CS. Then, the second stage of chemical strengthening treatment is performed under conditions that decrease the DOL and relatively increase the CS. This increases the CS of the outermost surface of the chemically strengthened glass, while suppressing the internal tensile stress area (St), thereby keeping the internal tensile stress (CT) low.

[0111] Because this chemically strengthened glass has excellent film adhesion to coating films such as antifouling layers, it is particularly useful as cover glass for mobile devices such as mobile phones, smartphones, personal digital assistants (PDAs), tablet devices, etc. Furthermore, it is also useful as cover glass for non-portable display devices such as televisions (TVs), personal computers (PCs), and touch panels, as well as for elevator walls, walls (full-surface displays) of buildings such as houses and buildings, building materials such as window glass, tabletops, interiors of automobiles and airplanes, and as cover glass for these, as well as for housings with curved shapes that are not flat, formed by bending or molding. [Example]

[0112] The present invention will be described below using examples, but the present invention is not limited thereto. Example 1 is an example of the present chemically strengthened glass, and Example 2 is a comparative example.

[0113] (Production of chemically strengthened glass) Glass raw materials were mixed to obtain the glass compositions shown in Table 1 in terms of oxide-based mole percentages, and chemically strengthened glasses were produced. As the glass raw materials, general glass raw materials such as oxides, hydroxides, carbonates, etc. were appropriately selected and weighed out so as to give 900 g of glass. The mixed glass raw materials were placed in a platinum crucible, melted at 1700°C, and degassed. The glass was poured onto a carbon board to obtain a glass block. The glass of Example 1 was crystallized in the form of a glass block at a temperature increase rate of 5°C / min, with a first stage at 550°C for 2 hours and a second stage at 720°C for 2 hours. Thereafter, the glasses of Examples 1 and 2 were polished under the conditions shown below to obtain plate-shaped glasses with a thickness of 0.70 mm. Polishing machine: Hamai Sangyo Co., Ltd. small polishing machine 4BF Abrasive: Slurry containing cerium oxide abrasive grains with an average particle size of approximately 1 μm (manufactured by Mitsui Mining & Smelting Co., Ltd.) Polishing pad: Nonwoven fabric (manufactured by Fujibo Ehime Co., Ltd.)

[0114] (chemical strengthening treatment) The obtained glass for chemical strengthening was chemically strengthened under the following conditions to obtain chemically strengthened glass. Example 1: NaNO3 99.7 mass% + LiNO3 0.3 mass% was immersed in molten salt at 450°C for 2.4 hours. Example 2: (1st stage) Immersed in molten salt containing 100% by mass of NaNO3 at 410°C for 2 hours. (Second stage) Immersed in molten salt of 99% by mass of KNO3 + 1% by mass of NaNO3 at 440°C for 1 hour.

[0115] [Table 1]

[0116] Next, the obtained chemically strengthened glass was subjected to the following evaluations.

[0117] (Haze value) The haze value (unit: %) was measured using a haze meter (HZ-V3 manufactured by Suga Test Instruments Co., Ltd.) under light source C. The haze values ​​of the chemically strengthened glasses of Examples 1 and 2 were both approximately 0.10%.

[0118] (Kurtosis Rku) The glass surface of chemically strengthened glass was photographed using an atomic force microscope (AFM, product name: Dimension ICON (Bruker)). The cantilever used was the standard one specified by the manufacturer. Images were taken in dynamic force mode over a scan area of ​​5 μm x 5 μm at a scan speed of 1 Hz (resolution: 256 x 256). The captured images were converted into roughness parameters using image analysis software (SPIP, Image Metrology) with tilt correction and global correction as a cubic function, and the kurtosis (Rku) of the surface roughness of the chemically strengthened glass was calculated in accordance with JIS B0601 (2001).

[0119] (Vickers hardness) The measurement was carried out using a Shimadzu micro Vickers hardness tester (HMV-2 manufactured by Shimadzu Corporation) by pressing an indenter under a load of 100 gf for 15 seconds.

[0120] Table 2 shows the Rku, Hv and (Rku / Hv)×1000 values ​​of each chemically strengthened glass.

[0121] (Peeling resistance of antifouling layer) Next, an antifouling layer was formed on the surface of the chemically strengthened glass in an area of ​​5 cm x 5 cm by the following procedure, and after rubbing and abrasion with an eraser, the water contact angle was measured. The evaluation results are shown in Table 2 and Figure 3.

[0122] ((Formation of antifouling layer)) The glass plate was washed with water and then further plasma-cleaned. A fluorine-containing organic compound (UD-509 manufactured by Daikin Industries, Ltd.) was then deposited on the glass plate using a vacuum deposition method with resistance heating. The pressure in the vacuum chamber during film deposition was 3.0 × 10 -3 Pa, and the deposition output was 318.5 kA / m 2 The deposition was carried out for 300 seconds at a temperature of 100° C. The thickness of the resulting antifouling layer was 15 nm.

[0123] ((Eraser friction and wear test)) Using a flat surface abrasion tester (triple type) (manufactured by Daiei Scientific Instruments Manufacturing Co., Ltd., device name: PA-300A), the surface of the antifouling layer was abraded 7,500 times with a 6 mm diameter eraser (Woojin Pink Pencil) under conditions of a load of 1 kgf, a stroke width of 40 mm, a speed of 40 rpm, and 25°C and 50% RH. After that, the water contact angle of the antifouling layer surface was measured.

[0124] ((Water contact angle measurement)) A droplet of approximately 1 μL of pure water was placed on the surface of the antifouling layer, and the contact angle of water was measured using a contact angle meter. The test was carried out six times or more, and the average value of the measured values ​​is shown in Table 2 as the water contact angle (°).

[0125] [Table 2]

[0126] The chemically strengthened glass of Example 1, an example, had a (Rku / Hv) × 1000 value of 4.4 or less, and was glass with appropriately controlled surface irregularities, so it had a large water contact angle even after eraser friction and abrasion, resulting in excellent film adhesion.On the other hand, the glass of Example 2, a comparative example, had a (Rku / Hv) × 1000 value of greater than 4.4, so it had a small water contact angle after eraser friction and abrasion, resulting in poor film adhesion.

[0127] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2020-138625) filed on August 19, 2020, the contents of which are incorporated herein by reference.

Claims

1. A plate-shaped chemically strengthened glass, The haze converted to a thickness of 0.70 mm is 1.0% or less, On at least one of the main surfaces, the ratio (Rku / Hv)×1000 of the kurtosis Rku of the surface irregularities to the Vickers hardness Hv is 1 or more and 4.4 or less; The base composition is expressed as mole percentage based on oxides, Contains 15% or more of Li 2 O, Chemically strengthened glass, which is a type of crystallized glass.

2. A plate-shaped chemically strengthened glass, On at least one of the main surfaces, The surface irregularity height frequency distribution is fitted with two or more normal distribution functions; On at least one of the main surfaces, the ratio (Rku / Hv)×1000 of the kurtosis Rku of the surface irregularities to the Vickers hardness Hv is 1 or more and 4.4 or less; The base composition is expressed as mole percentage based on oxides, Contains 15% or more of Li 2 O, Contains SiO 2 —Al 2 O 3 —Li 2 O crystals, Chemically strengthened glass, which is a type of crystallized glass.

3. SiO ２ -Al ２ O ３ -Li ２ The chemically strengthened glass according to claim 1, containing O-based crystals.

4. LiAlSi ２ O ６ , Li ２ Si ２ O ５ and Al ６ O １３ Si ２ The chemically strengthened glass according to claim 1 or 2, containing one or more crystals selected from the group consisting of:

5. The base composition is expressed as mole percentage based on oxides, SiO ２ 40 to 80% Al ２ O ３ を3~30%、 P ２ O ５ 0 to 5%, B ２ O ３ 0 to 10%, Li ２ Oを15~40%、 Na ２ Oを0~10%、 K ２ O 0 to 5%, MgO 0 to 5%, CaO 0 to 5%, SrO 0 to 5%, BaO 0 to 5%, ZrO ２ 1 to 5%, SnO ２ 0 to 4%, Y ２ O ３ Contains 0 to 4% of The chemically strengthened glass according to any one of claims 1 to 4.

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