Chemically strengthened glass, crystallized glass, and glass

Abstract

The present invention relates to a chemically strengthened glass which is a crystallized glass, wherein the composition of the central part in the thickness direction contains, in molar percentages in terms of oxides, 62-75% of SiO2, 2.2-6.0% of Al2O3, more than 0% and not more than 3% of P2O5, 20-27% of Li2O, more than 0% and not more than 5% of Na2O, 0-1% of K2O, 0-2% of MgO, 0-2% of CaO, 0-1% of SrO, 1-4.2% of ZrO2, 0-1% of SnO2, and substantially no Y2O3, while satisfying {[K2O] / [Na2O]} is 0-0.3 and[{[Al2O3}] / [ZrO2]} - {[B2O3] / [P2O5]}] is 0.5-1.5.

Description

Chemically strengthened glass, crystallized glass, and glass

[0001] The present invention relates to chemically strengthened glass, crystallized glass, and glass.

[0002] Thin, high-strength chemically strengthened glass is used as cover glass for displays of electronic devices such as mobile devices such as mobile phones and smartphones. Chemically strengthened glass is produced by bringing glass into contact with a molten salt composition such as sodium nitrate to cause ion exchange between alkali metal ions contained in the glass and alkali metal ions with a larger ionic radius contained in the molten salt composition, thereby forming a compressive stress layer from the surface to the interior of the glass.

[0003] Among electronic device housings equipped with chemically strengthened glass as a cover glass, particularly for mobile devices, the cover glass must be resistant to breakage when the housing is dropped from hand to the floor. To evaluate this breakage resistance, a "drop strength test" is used in which an electronic device housing or a simulated structure thereof is dropped freely and the height at which it breaks is evaluated.

[0004] In Patent Document 1, in order to increase the strength measured by the drop strength test in chemically strengthened glass, the compressive stress value CS at a depth of 50 μm from the glass surface is ５０ and the compressive stress value CS at the same depth of 90 μm ９０ is considered to be important.

[0005] It is also known that in order to increase the strength of glass measured by a drop strength test, the fracture toughness value K1c of the glass is increased, and crystallized glass having a crystalline phase is known as glass with a high fracture toughness value.

[0006] For example, Patent Document 2 discloses a crystallized glass having a fracture toughness value K1c of 1.13 MPa m １／２ Patent Document 3 discloses a glass-ceramic that satisfies a specific composition range and has a fracture toughness value K1c of 1.0 MPa m １／２ A glass-ceramic having a crystallinity of 0.15 to 0.25 μm is disclosed.

[0007] International Publication No. 2013 / 243574 Chinese Patent Application Publication No. 118771728 Chinese Patent Application Publication No. 118834018

[0008] As described in Patent Document 1, drop strength tests have been conducted up to now by freely dropping electronic device housings or simulated structures thereof onto #80 sandpaper or #180 sandpaper. This is because #80 and #180 have been used as sandpaper grits, taking into consideration that the coarser the grit of the sandpaper, i.e., the smaller the grit number, the lower the crack height.

[0009] In recent years, however, attention has begun to be paid to the evaluation of electronic device housings or their simulated structures when they are dropped freely onto coarser sandpaper, #60. It has been found that glass that exhibits high strength when dropped onto #80 or #180 sandpaper does not necessarily exhibit high strength when dropped onto #60 sandpaper.

[0010] Therefore, an object of the present invention is to provide chemically strengthened glass that exhibits high strength characteristics in a #60 sandpaper set drop strength test. Another object of the present invention is to provide glass-ceramics before chemical strengthening treatment that can be made into chemically strengthened glass having the above characteristics, and glass before crystallization treatment that can be made into the above glass-ceramics.

[0011] In the #60 sandpaper set drop strength test, cracks are deeper than in the #80 sandpaper set drop strength test and the #180 sandpaper set drop strength test, and the test is conducted under more severe conditions. And, as mentioned above, in the #180 sandpaper set drop strength test and the #80 sandpaper set drop strength test, CS ５０ and CS ９０ It has been considered important that

[0012] Based on this idea, it is presumed that in the #60 sandpaper set drop strength test, it is important to increase the compressive stress value at a position deeper than 90 nm from the glass surface.

[0013] However, in order to increase the compressive stress value at deeper positions, it is necessary to increase the overall compressive stress applied to the glass, which in turn increases the tensile stress applied to the glass, causing fragments to fly violently when the glass is shattered.

[0014] In response to this, the inventors conducted extensive research and discovered that the above problem can be solved by using glass-ceramics with a high fracture toughness value K1c and a low tensile stress value CT through chemical strengthening, leading to the completion of the present invention. Based on previous findings, it was predicted that glass that excels in the #60 sandpaper set drop strength test would be glass with a high compressive stress value, i.e., glass with a high tensile stress value corresponding to a high compressive stress value. Surprisingly, the present invention has been conceived to solve the above problem by using the opposite low tensile stress value.

[0015] That is, the gist of this embodiment relates to the following: [1] A crystallized glass having a crystalline phase, the composition of the center portion in the thickness direction being expressed in mole percentage based on oxides: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, P ２ O ５ More than 0% and less than 3%, Li ２ O 20-27%, Na ２ O more than 0% and less than 5%, K ２ O 0-1%, MgO 0-2%, CaO 0-2%, SrO 0-1%, ZrO ２ 1 to 4.2%, and SnO ２ 0 to 1%, Y ２ O ３ Substantially does not contain K ２ O and Na ２ Using the content ratio of O expressed in mole percentage, {[K ２ O] / [Na ２ O} is 0 to 0.3, ２ O ３ , ZrO ２ , B ２ O ３ and P２ O ５ Using the content ratio expressed in mole percentage, [{[Al ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O ５ [2] A chemically strengthened glass having a crystal phase, the composition of the center portion in the thickness direction is expressed in mole percentage based on oxides as follows: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, Li ２ O 20-27%, and ZrO ２ 1 to 4.2%, and the integral value of the tensile stress I ＣＴ (MPa μm) and the thickness direction length L of the tensile stress region ＣＴ (μm), {I ＣＴ / L ＣＴ} The average value of the tensile stress CT ａｖｅ Chemically strengthened glass having an integral value I of tensile stress of 60 MPa or less. ＣＴ (MPa μm) and the thickness direction length L of the tensile stress region ＣＴ (μm), {I ＣＴ / L ＣＴ} The average value of the tensile stress CT ａｖｅ [4] The chemically strengthened glass according to the above [1], wherein the crystalline phase is Li ２ Si ２ O ５ , LiAlSi ２ O ６ , LiAlSi ４ O １０ , Li ３ P.O. ４ [5] The chemically strengthened glass according to any one of [1] to [3], which contains at least one crystal selected from the group consisting of β-quartz solid solution and β-quartz solid solution. １／２ [6] The chemically strengthened glass according to any one of [1] to [4], wherein the compressive stress value CS at a depth of 50 μm from the surface is ５０[7] The chemically strengthened glass according to any one of [1] to [5], wherein the compressive stress value CS at a depth of 150 μm from the surface is 220 MPa or less. １５０ [8] The chemically strengthened glass according to any one of [1] to [7], wherein the value of Y represented by the following formula is 10 or more: Y = 0.1 × α - 0.05 × CT ａｖｅ α=200×K1c-100 CT ａｖｅ =I ＣＴ / L ＣＴ I ＣＴ : Integrated value of tensile stress (MPa μm) L ＣＴ : Length of tensile stress region in the plate thickness direction (μm) K1c: Fracture toughness value (MPa m １／２ ) [9] The chemically strengthened glass according to any one of [1] to [8], wherein the depth K-DOL from the surface of the compressive stress layer formed by K ions is 3 μm or more.

[10] The chemically strengthened glass according to any one of [1] to [9], wherein the compressive stress layer depth DOL is 100 μm or more.

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

[10] , wherein the compressive stress layer depth DOL is {t × 0.15} μm or more, where t (μm) is the thickness of the glass.

[12] Na ion concentration at a depth of 100 μm from the surface [Na] １００ is 2.5 mol% or more, and the compressive stress value CS at a depth of 100 μm from the surface １００

[13] The chemically strengthened glass according to any one of [1] to

[11] , wherein the Na ion concentration at a depth of 100 μm from the surface [Na] is 30 MPa or less. １００ and the Na ion concentration at a depth of 50 μm from the surface [Na] ５０ Using {[Na] ５０ / [Na] １００

[14] The chemically strengthened glass according to any one of [1] to

[12] , wherein the ratio represented by the formula {} is 1.4 or less. ０The chemically strengthened glass according to any one of [1] to

[13] , wherein the Young's modulus is 300 to 700 MPa.

[15] The chemically strengthened glass according to any one of [1] to

[14] , wherein the Young's modulus is 105 GPa or greater.

[16] The chemically strengthened glass according to any one of [1] to

[15] , wherein the average crack height measured by a sandpaper set drop strength test under the following conditions is 40 cm or greater. (Conditions) The test specimen is an electronic device equipped with chemically strengthened glass, or an electronic device simulation structure in which chemically strengthened glass and a housing for holding the chemically strengthened glass are integrated. The drop test is conducted by dropping the test specimen onto #60 sandpaper with the chemically strengthened glass facing downward. The test specimen is dropped from a height of 15 cm. If the chemically strengthened glass in the test specimen does not break upon dropping, the drop height is increased by 5 cm and the drop process is repeated. The height at which the chemically strengthened glass in the test specimen first breaks is defined as the crack height. The drop test is carried out on 10 test specimens, and the average crack height is taken as the average crack height.

[17] Al ２ O ３ and Na ２ Using the content ratio of O expressed in mole percentage, {[Al ２ O ３ ] / [Na ２

[18] The chemically strengthened glass according to any one of [1] to

[16] , wherein a value represented by the formula {Li, Li ... ２ O and ZrO ２ Using the content ratio expressed in mole percentage, {[Li ２ O] / [ZrO ２ ]} is 8 or more.

[19] The chemically strengthened glass according to any one of [1] to

[18] above, having a crystallization rate of 40 mass% or more.

[20] The chemically strengthened glass according to any one of [1] to

[19] above, having an average particle size of crystals constituting the crystalline phase of 10 to 100 nm.

[21] The chemically strengthened glass according to any one of [1] to

[20] above, having a transmittance of 80% or more for light with a wavelength of 600 nm when converted into a glass with a thickness of 0.6 mm.

[0016]

[22] A crystallized glass having a crystalline phase, the composition of which is expressed in mole percentage based on oxides: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, P ２ O ５ More than 0% and less than 3%, Li ２ O 20-27%, Na ２ O more than 0% and less than 5%, K ２ O 0-1%, MgO 0-2%, CaO 0-2%, SrO 0-1%, ZrO ２ 1 to 4.2%, and SnO ２ 0 to 1%, Y ２ O ３ Substantially does not contain K ２ O and Na ２ Using the content ratio of O expressed in mole percentage, {[K ２ O] / [Na ２ O} is 0 to 0.3, ２ O ３ , ZrO ２ , B ２ O ３ and P ２ O ５ Using the content ratio expressed in mole percentage, [{[Al ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O ５

[23] The crystallized glass, wherein the value represented by the formula (I) is 0.5 to 1.5. ２ Si ２ O ５ , LiAlSi ２ O ６ , LiAlSi ４ O １０ , Li ３ P.O. ４

[24] The glass-ceramics according to

[22] , which contains at least one crystal selected from the group consisting of β-quartz solid solution and β-quartz solid solution. １／２

[25] The glass-ceramics according to any one of

[22] to

[24] , having a Young's modulus of 105 GPa or more.

[26] Al ２ O ３ and Na ２ Using the content ratio of O expressed in mole percentage, {[Al ２ O ３ ] / [Na ２

[27] The glass-ceramics according to any one of

[22] to

[25] , wherein the value represented by {Li + Li + O} is greater than 0 and not greater than 0.23. ２ O and ZrO ２ Using the content ratio expressed in mole percentage, {[Li ２ O] / [ZrO ２ ]} is 8 or more.

[28] The glass-ceramics according to any one of the above

[22] to

[27] , having a crystallization rate of 40 mass% or more.

[29] The glass-ceramics according to any one of the above

[22] to

[28] , having an average particle size of crystals constituting the crystalline phase of 10 to 100 nm.

[30] The glass-ceramics according to any one of the above

[22] to

[29] , having a transmittance of 80% or more for light with a wavelength of 600 nm when converted into a glass with a thickness of 0.6 mm.

[0017]

[31] The composition is expressed in mole percentage based on oxides, and is: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, P ２ O ５ More than 0% and less than 3%, Li ２ O 20-27%, Na ２ O more than 0% and less than 5%, K ２ O 0-1%, MgO 0-2%, CaO 0-2%, SrO 0-1%, ZrO ２ 1 to 4.2%, and SnO ２ 0 to 1%, Y ２ O ３ Substantially does not contain K ２ O and Na ２ Using the content ratio of O expressed in mole percentage, {[K２ O] / [Na ２ O} is 0 to 0.3, ２ O ３ , ZrO ２ , B ２ O ３ and P ２ O ５ Using the content ratio expressed in mole percentage, [{[Al ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O ５ ]}] is 0.5 to 1.5.

[32] Al ２ O ３ and Na ２ Using the content ratio of O expressed in mole percentage, {[Al ２ O ３ ] / [Na ２

[33] The glass according to the above

[31] , wherein the value represented by the formula {Li, Li ... ２ O and ZrO ２ Using the content ratio expressed in mole percentage, {[Li ２ O] / [ZrO ２ ]} is 8 or more.

[0018] According to the present invention, chemically strengthened glass having high strength characteristics in a #60 sandpaper set drop strength test can be obtained. In addition, it is possible to obtain crystallized glass that becomes the chemically strengthened glass having the above characteristics when subjected to chemical strengthening treatment, and glass that becomes the above crystallized glass when subjected to crystallization treatment.

[0019] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the embodiments described below. In this specification, the term "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. Furthermore, in this specification, mass % and weight %, and parts by mass and parts by weight have the same meaning.

[0020] In this specification, the composition of the thickness direction center of chemically strengthened glass is the same as the composition of the glass before chemical strengthening treatment. Except in cases where extreme ion exchange treatment has been performed, the glass composition deeper than the compressive stress layer depth DOL of the chemically strengthened glass can be considered to be the same as the composition of the thickness direction center of the chemically strengthened glass. Also, in this specification, the composition of crystallized glass is the same as the composition of amorphous glass (mother glass) before crystals are precipitated. In other words, the composition of the amorphous glass before crystallization, the composition of the crystallized glass after crystallization treatment, and the composition of the thickness direction center of the chemically strengthened glass after further chemical strengthening treatment of the crystallized glass can all be considered to be the same. Regarding crystallized glass, the composition of the glass before crystallization and the composition of the amorphous phase (residual glass phase) in the crystallized glass are strictly different. The composition of the amorphous phase in crystallized glass is determined from the composition of the crystallized glass and the composition and content of the crystalline phase.

[0021] Chemically strengthened glass The chemically strengthened glass according to this embodiment is glass-ceramics having a crystalline phase. That is, the glass-ceramics has an ion-exchanged compressive stress layer on its surface due to chemical strengthening treatment.

[0022] In a first aspect of the chemically strengthened glass according to the present embodiment, the composition of the center portion in the thickness direction satisfies the following in terms of mole percentage based on oxides: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, Li ２ O 20-27%, and ZrO ２ 1 to 4.2%.

[0023] In addition to the above, the first aspect of the chemically strengthened glass according to this embodiment is the integral value I of tensile stress. ＣＴ (MPa μm) and the thickness direction length L of the tensile stress region ＣＴ (μm), {I ＣＴ / L ＣＴ} The average value of the tensile stress CT ａｖｅ is 60 MPa or less.

[0024] In a second aspect of the chemically strengthened glass according to the present embodiment, the composition at the center in the thickness direction satisfies the following in terms of mole percentage based on oxides: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, P ２ O ５ More than 0% and less than 3%, Li ２ O 20-27%, Na ２ O more than 0% and less than 5%, K ２ O 0-1%, MgO 0-2%, CaO 0-2%, SrO 0-1%, ZrO ２ 1-4.2%, SnO ２ 0 to 1%, and Y ２ O ３ It is substantially free of

[0025] In addition to the above, a second aspect of the chemically strengthened glass according to this embodiment is that the composition at the center in the thickness direction contains K ２ O and Na ２ Using the content ratio of O expressed in mole percentage, {[K ２ O] / [Na ２ O} is 0 to 0.3, and Al ２ O ３ , ZrO ２ , B ２ O ３ and P ２ O ５ Using the content ratio expressed in mole percentage, [{[Al ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O ５ ]}] is 0.5 to 1.5.

[0026] In the present invention, in order to have high strength characteristics in a #60 sandpaper set drop strength test, the fracture toughness value K1c is high and the average value of the tensile stress CT ａｖｅIt has been found that it is important to use chemically strengthened glass-ceramics with low compressive stress. As mentioned above, based on previous findings, it was predicted that glasses that excel in the #60 sandpaper set drop strength test would be glasses with high compressive stress, i.e., glasses with high tensile stress corresponding to high compressive stress. In contrast, the present invention has surprisingly achieved the opposite: that the above problem can be solved by using low tensile stress.

[0027] First, in the #60 sandpaper drop strength test, a portion of the glass hits the abrasive grains of the sandpaper simulating a floor surface, causing a crack. The crack then propagates from the starting point. It is presumed that the propagation of the crack depends on whether the tensile stress at the tip of the crack is sufficient to support the energy required for crack propagation. In an actual drop strength test, the glass does not break immediately upon contact with the sandpaper; rather, the crack propagates when the glass is bent as it bounces off the sandpaper. However, strictly speaking, cracks caused by contact with the sandpaper and crack propagation caused by bending stress cannot be separated, resulting in variability. Therefore, in this specification, the average crack height measured in the #60 sandpaper drop strength test using 10 test specimens is used as an indicator of the strength characteristics in the #60 sandpaper drop strength test.

[0028] In order to solve the above problem, the fracture toughness value K1c is examined. The fracture toughness value K1c is a value proportional to Young's modulus and surface energy. Young's modulus reflects the properties of the crystallized glass itself. Furthermore, it is believed that the surface energy is significantly affected not only by the properties of the crystallized glass itself but also by chemical strengthening. Therefore, in this embodiment, the presence of a crystalline phase increases the Young's modulus of the glass, resulting in high rigidity and small bending. As a result, the concentration of stress at the crack tip is reduced, which is thought to be one of the factors behind the excellent strength in the #60 sandpaper set drop strength test. Furthermore, in order to achieve a high Young's modulus, it is important that the crystallized glass has a crystalline phase. In particular, as the crystalline phase, for example, lithium disilicate (lithium disilicate, Li ２ Si ２ O ５ ) crystals and petalite (LiAlSi ４ O １０ ) crystals are preferred.

[0029] Furthermore, since the chemically strengthened glass according to this embodiment is a crystallized glass, the presence of grain boundaries due to crystallization and cleavage planes resulting from the crystal structure inhibit crack propagation. Therefore, more energy is required for crack propagation than in amorphous glass. Therefore, by optimizing the crystallization rate of the crystallized glass, the average particle size of the crystals constituting the crystalline phase, the type of crystals constituting the crystalline phase, etc., the energy required for crack propagation can be increased, and superior strength can be achieved in a #60 sandpaper set drop strength test.

[0030] Next, the average value of the tensile stress CT ａｖｅ However, the average value of tensile stress CT ａｖｅ is the integral value of tensile stress I ＣＴ (MPa μm) and the thickness direction length L of the tensile stress region ＣＴ (μm), {I ＣＴ / L ＣＴ}. Here, the inventors focused on the depth of cracks generated by a #60 sandpaper set drop strength test. They found that the depth was deeper than 120 μm, reaching approximately 150 μm. Generally, a depth of 150 μm from the surface falls within the tensile stress region of chemically strengthened glass. The smaller the absolute value of the tensile stress, the less the cracks in this region will propagate. Based on this, in this embodiment, the average value CT of the tensile stress ａｖｅ By lowering the value, it was found that excellent strength in a #60 sandpaper set drop strength test could be achieved.

[0031] In light of the above, the first aspect of this embodiment is the average value of the tensile stress CT ａｖｅ The present invention relates to a chemically strengthened glass obtained by chemically strengthening glass-ceramics having a crystalline phase with a tensile stress of 60 MPa or less. ａｖｅ As the composition of the center portion in the thickness direction where the strength is 60 MPa or less, SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, Li ２ O 20-27%, and ZrO ２ 1 to 4.2%.

[0032] In addition, as a second aspect of the chemically strengthened glass according to this embodiment, it is a crystallized glass having a crystalline phase, and the composition of the center portion in the thickness direction satisfies a specific range or relationship. As a result, it has a high K1c and a low average value of tensile stress CT ａｖｅ This allows for both of these to be achieved, and excellent strength can be achieved in a #60 sandpaper set drop strength test.

[0033] In addition, if only chemically strengthened glass with low tensile stress is to be obtained, it is possible to consider a method of suppressing the diffusion of Na ions and K ions used in ion exchange by shortening the time for ion exchange treatment or lowering the temperature of the molten salt for ion exchange. However, when the above method is adopted, the value of the compressive stress layer depth DOL also becomes small, and the glass becomes more likely to break if a crack occurs. In contrast, in both the first and second aspects of this embodiment, the chemically strengthened glass is made of crystallized glass having a crystalline phase, and the composition of the center in the thickness direction is set to a specific range. Even if ions diffuse to a sufficient depth to form a compressive stress layer, the compressive stress value is not excessively large, and the average value CT of low tensile stress is maintained. ａｖｅ It was discovered that this could be achieved.

[0034] <Composition> The composition of the center portion of the chemically strengthened glass in the thickness direction, i.e., the composition of the chemically strengthened crystallized glass, will be described below. The content ratio of each component is expressed as a mole percentage based on the oxide unless otherwise specified. The composition of chemically strengthened glass can be identified using a conventionally known method. For example, the composition can be identified by wet chemical analysis or quantitative analysis using a fluorescent X-ray calibration curve.

[0035] SiO ２ is a component that constitutes the glass network and also a component that constitutes lithium disilicate crystals. SiO in chemically strengthened glass ２ The content ratio of is 62 to 75%. Here, from the viewpoint of facilitating the formation of lithium disilicate crystals, the content ratio is 62% or more, preferably 64% or more, more preferably 66% or more, and even more preferably 68% or more. Furthermore, from the viewpoint of facilitating the formation of lithium disilicate crystals and enhancing the meltability of the glass, the content ratio is 75% or less, preferably 73% or less, more preferably 72% or less, even more preferably 70% or less, and particularly preferably 69% or less.

[0036] Li ２ O is a component of lithium disilicate crystals, and Li ２Li ions that make up O are ion-exchanged with Na ions, which causes compressive stress to form near the surface of the glass-ceramics. ２ The O content is 20 to 27%. From the viewpoint of facilitating the formation of lithium disilicate crystals and increasing compressive stress, the O content is 20% or more, preferably 21% or more, more preferably 22% or more, and even more preferably 23% or more. From the viewpoint of facilitating the formation of lithium disilicate crystals and increasing the chemical durability of the glass, the O content is 27% or less, preferably 26.5% or less, more preferably 26% or less, even more preferably 25% or less, and particularly preferably 24% or less.

[0037] Al ２ O ３ Al is a component that improves ion exchangeability during chemical strengthening treatment and increases the surface compressive stress after chemical strengthening treatment. ２ O ３ The content ratio is 2.2 to 6.0%. Here, from the viewpoint of performing the chemical strengthening treatment suitably, the content ratio is 2.2% or more, preferably 2.4% or more, more preferably 2.5% or more, more preferably 2.6% or more, even more preferably 2.8% or more, and particularly preferably 3.2% or more. Furthermore, from the viewpoint of facilitating the formation of lithium disilicate crystals, the content ratio is 6.0% or less, preferably 5.5% or less, more preferably 5.0% or less, and even more preferably 4.5% or less.

[0038] ZrO ２ is a thickening component that increases the viscosity when melted, and at the same time, is a component that increases the surface compressive stress due to ion exchange. ２ It has been found that by adding an appropriate amount of ZrO, phase separation can be suitably controlled so that crystallization can be easily performed while maintaining high transparency. As a result, when the glass is made into a crystallized glass, the crystallization degree can be increased while maintaining high transparency, and higher strength can be achieved. ２The content ratio of is 1 to 4.2%. Here, from the viewpoint of controlling phase separation and from the viewpoint of realizing higher transparency of the glass by acting as a thickening component and slowing the growth rate of crystals that become crystalline phases to form fine crystals, the content ratio is 1% or more, preferably 1.5% or more, more preferably 1.6% or more, even more preferably 1.7% or more, even more preferably 2.0% or more, and particularly preferably 2.5% or more. Furthermore, from the viewpoint of suppressing devitrification during melting, the content ratio is 4.2% or less, preferably 4.0% or less, more preferably 3.8% or less, even more preferably 3.5% or less, even more preferably 3.0% or less, or may be 2.5% or less, or may be 2.4% or less.

[0039] In addition, ZrO in the chemically strengthened glass according to this embodiment ２ The content ratio is preferably 1 to 10 mass% when expressed as a mass percentage based on oxides. Here, from the viewpoint of controlling phase separation and acting as a thickening component to slow the growth rate of crystals that become crystalline phases and form fine crystals, thereby realizing higher transparency of the crystallized glass, the content ratio is preferably 1 mass% or more, more preferably 2.5 mass% or more, even more preferably 3.2 mass% or more, and even more preferably 3.7 mass% or more. Furthermore, from the viewpoint of suppressing devitrification during melting, the content ratio is preferably 10 mass% or less, more preferably less than 5 mass%, even more preferably 4.8 mass% or less, and may be 4.5 mass% or less, or may be 4.4 mass% or less.

[0040] P ２ O ５ is a component that promotes crystallization. ２ O ５ The content of P is preferably more than 0% and not more than 3%. ２ O ５It is preferable that the content is 0.2% or more, more preferably 0.5% or more, even more preferably 0.7% or more, and particularly preferably 0.8% or more. From the viewpoint of suppressing phase separation during melting and a decrease in acid resistance, the content is preferably 3% or less, more preferably 2.5% or less, even more preferably 2.0% or less, and most preferably 1.5% or less.

[0041] Na ２ O is Na ２ It is a component that generates compressive stress by ion-exchanging Na ions that make up O with K ions, and the inclusion of a small amount of Na can increase the stability of the glass. ２ The content of O is preferably more than 0% and not more than 5%. Here, from the viewpoint of increasing the compressive stress and improving the stability, the content is preferably more than 0%, i.e., Na ２ It preferably contains O, more preferably 0.5% or more, even more preferably 1.0% or more, and even more preferably 2.0% or more. From the viewpoint of maintaining chemical durability, the content is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0042] K ２ O is a component that enhances chemical strengthening properties and suppresses phase separation. ２ The content of O is preferably 0 to 1%. ２ The content of O is 0%, that is, it may not be contained, but K ２ When O is contained, from the viewpoint of enhancing the stability of the glass, the content is preferably 0.02% or more, more preferably 0.2% or more, and even more preferably 0.4% or more. From the viewpoint of maintaining chemical durability, the content is preferably 1% or less, more preferably 0.9% or less, even more preferably 0.8% or less, even more preferably 0.7% or less, and particularly preferably 0.6% or less.

[0043] MgO is a component that improves the meltability of glass. The MgO content in chemically strengthened glass is preferably 0 to 2%. Here, the MgO content may be 0%, i.e., not contained. However, if MgO is contained, from the viewpoints of meltability and strength, the content is preferably 0.03% or more, more preferably 0.2% or more, and even more preferably 0.4% or more. Furthermore, from the viewpoint of maintaining good ion exchange performance, the content is preferably 2% or less, more preferably 1.5% or less, and even more preferably 1.0% or less.

[0044] CaO is a component that improves the meltability of glass. The CaO content in chemically strengthened glass is preferably 0 to 2%. Here, the CaO content may be 0%, i.e., not contained, but if CaO is contained, from the viewpoints of meltability and strength, the content is preferably 0.03% or more, more preferably 0.2% or more, and even more preferably 0.4% or more. Furthermore, from the viewpoint of maintaining good ion exchange performance, the content is preferably 2% or less, more preferably 1.5% or less, even more preferably 1.0% or less, and particularly preferably 0.8% or less.

[0045] SrO is a component that improves the meltability of glass. The SrO content in chemically strengthened glass is preferably 0 to 1%. Here, the SrO content may be 0%, i.e., not contained. However, if SrO is contained, from the viewpoints of meltability and strength, the content is preferably 0.03% or more, more preferably 0.2% or more, and even more preferably 0.4% or more. Furthermore, from the viewpoint of maintaining good ion exchange performance, the content is preferably 1% or less, more preferably 0.9% or less, and even more preferably 0.7% or less.

[0046] SnO ２ is a fining agent during melting and also a component that forms crystal nuclei. ２ The content of SnO is preferably 0 to 1%. ２When containing, it acts as a component for generating crystal nuclei and forms minute crystals, so that the glass can be highly transparent. From the viewpoint of this, the content is preferably 0.02% or more, more preferably 0.1% or more, and even more preferably 0.2% or more. Furthermore, from the viewpoint of suppressing defects due to unmelted matter, the content is preferably 1% or less, more preferably 0.9% or less, even more preferably 0.7% or less, and most preferably 0.5% or less.

[0047] B ２ O ３ is a component that improves chipping resistance and melting property. ２ O ３ The content of B is preferably 0 to 4%. ２ O ３ The content of B is 0%, that is, it may not be contained. ２ O ３ When containing, from the viewpoint of obtaining good chipping resistance and meltability, the content is preferably 0.3% or more, more preferably 0.5% or more, even more preferably 1.0% or more, and particularly preferably 1.5% or more. In addition, from the viewpoint of suppressing the occurrence of striae and phase separation during melting and maintaining the quality of chemically strengthened glass, the content is preferably 4% or less, more preferably 3.5% or less, even more preferably 3.0% or less, and even more preferably 2.5% or less.

[0048] ZnO is a component that enhances the meltability of glass. The ZnO content in chemically strengthened glass is preferably 0 to 2%. Here, the ZnO content may be 0%, i.e., not contained, but if ZnO is contained, from the viewpoint of obtaining good meltability, the content is preferably 0.2% or more, more preferably 0.5% or more, and even more preferably 1.0% or more. Furthermore, from the viewpoint of improving weather resistance, the content is preferably 2% or less, more preferably 1.8% or less, even more preferably 1.6% or less, and even more preferably 1.4% or less.

[0049] TiO ２ is a thickening component that increases the viscosity when melted, and also a component that increases UV resistance. ２The content of TiO is preferably 0 to 1%. ２ The content ratio of TiO is 0%, that is, it may not be contained. ２ When it is contained, it acts as a thickening component, slows down the growth rate of crystals that become crystalline phases, and forms fine crystals, so that high transparency of the glass is realized. From the viewpoint of realizing this, the content is preferably 0.01% or more, more preferably 0.1% or more, and even more preferably 0.3% or more. Furthermore, from the viewpoint of suppressing a decrease in the haze value due to coloring, the content is preferably 1% or less, more preferably 0.8% or less, and even more preferably 0.6% or less.

[0050] Y ２ O ３ is a thickening component that increases the viscosity during melting, and at the same time, it is a component that increases the mechanical strength of the glass. It is also a component that increases the refractive index. ２ O ３ Therefore, the chemically strengthened glass according to this embodiment has a function of inhibiting the formation of crystal nuclei. ２ O ３ In this specification, "substantially free of" means that the content is at or below the impurity level contained in raw materials, etc., i.e., it is not intentionally added, and the content is, for example, less than 0.01%.

[0051] Furthermore, other components such as coloring components may be added as appropriate within a range that does not inhibit the achievement of desired properties of the chemically strengthened glass. Examples of such other components include BaO, La, ２ O ３ , Nb ２ O ５ , Ta ２ O ５ , CeO ２ , Co ３ O ４ , MnO ２ , Fe ２ O ３ , NiO, CuO, Cr ２ O ３ , V ２ O ５ , Bi ２ O ３ , SeO ２, Er ２ O ３ , Nd ２ O ３ The total content of the other components in the chemically strengthened glass is preferably 0.2% or less. In addition, if the light transmittance of the chemically strengthened glass is desired to be higher, it is preferable that the coloring component is not substantially contained.

[0052] In addition, SO is used as a fining agent when melting glass. ３ , chloride, fluoride, As ２ O ３ , Sb ２ O ３ The content of each of the fining agents is preferably 0.3% or less, more preferably 0.1% or less, and most preferably substantially none.

[0053] The chemically strengthened glass according to this embodiment has a composition at the center in the thickness direction of SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, Li ２ O 20-27%, and ZrO ２ In addition to the above, it is preferable that P ２ O ５ More than 0% and less than 3%, Na ２ O More than 0% but not more than 5%, K ２ O 0-1%, MgO 0-2%, CaO 0-2%, SrO 0-1%, SnO ２ 0-1%, and Y ２ O ３ It is more preferable that one or more of the following conditions are satisfied, even more preferable that three or more of the following conditions are satisfied, even more preferable that five or more of the following conditions are satisfied, especially preferable that seven or more of the following conditions are satisfied, and it is particularly preferable that all eight of the following conditions are satisfied.

[0054] In addition to the content ratios of each of the above components, the chemically strengthened glass according to this embodiment more preferably satisfies one or more of the following relationships (1) to (4) expressed using the content ratios of each component, more preferably satisfies two or more, even more preferably satisfies three or more, and particularly preferably satisfies all four. Among them, it is even more preferable to satisfy (1) and (2).

[0055] (1) {[K ２ O] / [Na ２ O]} is 0 to 0.3. ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O ５ (3) The value represented by {[Al ２ O ３ ] / [Na ２ O]} is greater than 0 and not greater than 0.23. ２ O] / [ZrO ２ ]} is 8 or more.

[0056] Of the above relationships, (1) is {[K ２ O] / [Na ２ O]} is 0 to 0.3. This value contributes to the exchange characteristics of K ions. Therefore, the chemically strengthened glass according to this embodiment has K ２ It may not contain O, that is, the value may be 0. ２ When O is contained, the value may be 0.03 or more, or may be 0.05 or more, but from the viewpoint of reducing charging characteristics, the value is preferably 0.3 or less, more preferably 0.27 or less, even more preferably 0.25 or less, and particularly preferably 0.23 or less.

[0057] Of the above relationships, (2) is [{[Al ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O ５]}] is 0.5 to 1.5. ２ O ３ ] / [ZrO ２ ]} is an index of the K ion and Na ion exchange properties, and ２ O ３ ] / [P ２ O ５ The value expressed by [{[Al ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O ５ From the viewpoint of enhancing the chemical strengthening properties, the value represented by {[Al ion exchange coefficient (Al ion exchange coefficient)}} is preferably 0.5 or more, more preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.8 or more, and particularly preferably 0.9 or more. From the viewpoint of facilitating the nucleation of crystallization, the value is preferably 1.5 or less, more preferably 1.3 or less, more preferably 1.2 or less, even more preferably 1.1 or less, and particularly preferably 0.9 or less. In addition, the value represented by {[Al ion exchange coefficient (Al ion exchange coefficient)}}], which is an index of the K ion and Na ion exchange properties, is preferably 0.5 or more, more preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.8 or more, and particularly preferably 0.9 or more. ２ O ３ ] / [ZrO ２ ]} is preferably 0.7 to 3.0. Here, the value is preferably 0.7 or more, more preferably 0.8 or more, even more preferably 0.9 or more, even more preferably 1.0 or more, and particularly preferably 1.1 or more. The value is preferably 3.0 or less, more preferably 2.0 or less, even more preferably 1.5 or less, and even more preferably 1.2 or less.

[0058] Among the above relationships, (3) is {[Al ２ O ３ ] / [Na ２ O]} is more than 0 and 2.3 or less. This value contributes to the exchange characteristics of Na ions and resistance to alkali. ２ O ３However, from the viewpoint of enhancing the Na ion exchange properties, the value is more preferably 0.1 or more, even more preferably 0.3 or more, and most preferably 0.5 or more. On the other hand, from the viewpoint of enhancing the alkali resistance, the value is preferably 2.3 or less, more preferably 1.9 or less, even more preferably 1.7 or less, even more preferably 1.2 or less, and particularly preferably 1.0 or less.

[0059] Among the above relations, (4) is {[Li ２ O] / [ZrO ２ ]} is 8 or more, preferably 8 to 20. This value contributes to the Li ion exchange properties and alkali resistance. From the viewpoint of improving the Li ion exchange properties, the value is preferably 8 or more, more preferably 9 or more, even more preferably 11 or more, and particularly preferably 13 or more. On the other hand, from the viewpoint of improving the alkali resistance, the value is preferably 20 or less, more preferably 17 or less, even more preferably 15 or less, and particularly preferably 14 or less.

[0060] <Crystalline Phase> The chemically strengthened glass according to this embodiment is a crystallized glass having a crystalline phase. The crystalline phase is not particularly limited, but may be, for example, Li ２ Si ２ O ５ (lithium disilicate crystal), LiAlSi ２ O ６ (β-spodumene crystal), LiAlSi ４ O １０ (Petalite crystal), Li ３ P.O. ４ (lithium phosphate crystal), β-quartz solid solution (Li ｘ Al ｘ Si ３－ｘ O ６ bergerite crystals), Li ２ SiO ３ (lithium metasilicate crystal), LiAlSiO ４ (eucryptite crystal), Al ４＋２ｘ Si ２－２ｘ O １０－ｘ(0.2≦x≦0.5, mullite crystal), etc. However, the present invention is not limited to these and may be appropriately selected according to the desired properties.

[0061] Among these, from the viewpoint of increasing the strength of chemically strengthened glass, particularly obtaining a higher fracture toughness value K1c, it is preferable to use Li as a crystalline phase. ２ Si ２ O ５ , LiAlSi ２ O ６ , LiAlSi ４ O １０ , Li ３ P.O. ４ and β-quartz solid solution, and ２ Si ２ O ５ and LiAlSi ４ O １０ It is more preferable that the crystal contains at least one of the following crystals: Li ２ Si ２ O ５ It is more preferred that the composition comprises:

[0062] For example, from the viewpoint of facilitating ion exchange by chemical strengthening treatment, the crystalline phase may be only lithium disilicate crystals, but may further include β-spodumene crystals, petalite, β-quartz, lithium metasilicate, etc. It may also include.

[0063] Furthermore, when it is desired to obtain crystallized glass having higher strength, the crystal phase may consist of only lithium disilicate crystals, but may also contain β-spodumene crystals, petalite, β-quartz, lithium metasilicate, mullite, etc.

[0064] Furthermore, when it is desired to achieve higher transparency, the crystalline phase may consist of only lithium disilicate crystals, but may also contain petalite, β-quartz, lithium metasilicate, lithium phosphate, or the like.

[0065] The type of crystals constituting the above crystalline phase can be selected mainly depending on the composition of the glass-ceramics and the crystallization conditions.

[0066] The presence of the crystalline phase can be confirmed by observing diffraction peaks indicative of crystals in the XRD pattern obtained by powder X-ray diffraction (XRD). Heat treatment of amorphous glass (mother glass) that does not exhibit diffraction peaks indicative of crystals can produce crystallized glass with a crystalline phase in which crystals are precipitated. Furthermore, chemical strengthening of the crystallized glass does not significantly affect the crystalline phase. The XRD measurement is performed using CuKα radiation in the 2θ range of 10° to 80°. From the diffraction pattern and diffraction intensity obtained as a result of the measurement, Rietveld analysis can be used to identify the crystalline structure of the crystals that make up the crystalline phase, the content ratio of each crystalline phase, and the total content ratio (degree of crystallinity) of the crystalline phase. 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).

[0067] When the crystalline phase contains lithium disilicate crystals, the content of lithium disilicate crystals in the crystalline phase is preferably 60% by mass or more, more preferably 60 to 100% by mass. From the viewpoint of achieving higher strength, the content is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more. The content may also be 100% by mass, i.e., the crystalline phase may consist solely of lithium disilicate crystals. From the viewpoint of bendability, other crystals may also be contained, in which case the content of lithium disilicate crystals in the crystalline phase may be 95% by mass or less, or may be 85% by mass or less.

[0068] The crystallization rate of the chemically strengthened glass according to this embodiment, i.e., the content ratio of the crystalline phase (degree of crystallization), is preferably 40% by mass or more, more preferably 40 to 80% by mass. From the viewpoint of achieving higher strength, the crystallization rate is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. Furthermore, from the viewpoint of maintaining high transparency and three-dimensional formability, the content ratio of the crystalline phase is preferably 80% by mass or less, more preferably 70% by mass or less, and more preferably 65% ​​by mass or less. When the chemically strengthened glass according to this embodiment contains two or more types of crystals as crystalline phases, the crystallization rate refers to the total content ratio of these. The crystallization rate can be adjusted by the composition of the crystallized glass, the temperature, time, heating rate, etc. during crystallization.

[0069] In the chemically strengthened glass according to this embodiment, the average particle size of the crystals constituting the crystalline phase is preferably 10 to 100 nm. From the viewpoint of achieving higher strength, the average particle size is preferably 10 nm or more, more preferably 20 nm or more, even more preferably 30 nm or more, and even more preferably 40 nm or more. From the viewpoint of achieving higher transparency, the average particle size is preferably 100 nm or less, more preferably 90 nm or less, even more preferably 80 nm or less, and even more preferably 60 nm or less. The average particle size can be measured by observation with a scanning electron microscope (SEM). The average particle size can also be adjusted by adjusting the heat treatment conditions. The average particle size can be adjusted by the temperature and time during crystallization, the cooling rate during glass molding, and the like.

[0070] <Strengthened Layer> The chemically strengthened glass according to this embodiment is crystallized glass having an ion-exchange layer on the surface thereof. By ion exchange, a compressive stress layer is formed on the outermost surface thereof, and a tensile stress layer is formed inside the outermost surface thereof.

[0071] The integrated value I of tensile stress of the chemically strengthened glass according to this embodiment ＣＴ (MPa μm) and the thickness direction length L of the tensile stress region ＣＴ (μm), {I ＣＴ / L ＣＴ} The average value of the tensile stress CT ａｖｅAs mentioned above, the cracks generated by the #60 sandpaper set drop strength test are deep and fall within the tensile stress region of chemically strengthened glass. Therefore, the average value of the tensile stress in this region, CT ａｖｅ By reducing this, the progression of cracks is suppressed, and excellent strength can be achieved in a #60 sandpaper set drop strength test.

[0072] From the above viewpoint, the average value CT of the tensile stress of the chemically strengthened glass according to this embodiment ａｖｅ is preferably 60 MPa or less, more preferably 50 MPa or less, and even more preferably 40 MPa or less. Although the lower limit is not particularly limited, from the viewpoint of obtaining a certain or higher compressive stress value, the average value CT of the tensile stress is ａｖｅ The average value of the tensile stress CT may be 10 MPa or more, or 20 MPa or more. ａｖｅ Although it is partly affected by the chemical strengthening treatment conditions, it can also be adjusted by the composition of the center part in the thickness direction of the chemically strengthened glass.

[0073] The average value of the tensile stress CT ａｖｅ The stress profile, such as the compressive stress value, can be measured using, for example, a scattered light photoelastic stress meter (SLP) or a film stress measurement (FSM).

[0074] The method using a scattered light photoelastic stress meter (SLP) can measure the compressive stress resulting from Li—Na exchange inside the glass, which is a region several tens of micrometers or more deep from the glass surface. On the other hand, the method using a glass surface stress meter (FSM) can measure the compressive stress resulting from Na—K exchange in the glass surface layer, which is a shallow region several tens of micrometers or less from the glass surface (see, for example, WO 2018 / 056121 and WO 2017 / 115811).

[0075] Maximum CT of tensile stress of chemically strengthened glass according to this embodiment ｍａｘHere, from the viewpoint of realizing superior strength in a #60 sandpaper set drop strength test, the maximum tensile stress CT ｍａｘ is preferably 120 MPa or less, more preferably 110 MPa or less, even more preferably 100 MPa or less, and even more preferably 80 MPa or less. Although the lower limit is not particularly limited, from the viewpoint of obtaining a certain or higher compressive stress value, the maximum value CT of the tensile stress is ｍａｘ may be 30 MPa or more, 40 MPa or more, or 50 MPa or more.

[0076] The integral value I of the tensile stress of the chemically strengthened glass according to this embodiment ＣＴ Here, from the viewpoint of realizing superior strength in a #60 sandpaper set drop strength test, the integral value I of the tensile stress is preferably 8000 to 33000 MPa μm. ＣＴ is preferably 8000 MPa μm or more, more preferably 12000 MPa μm or more, even more preferably 15000 MPa μm or more, and even more preferably 18000 MPa μm or more. In addition, from the viewpoint of realizing superior strength in a #60 sandpaper set drop strength test, the integrated value I ＣＴ is preferably 33,000 MPa·μm or less, more preferably 30,000 MPa·μm or less, even more preferably 28,000 MPa·μm or less, and even more preferably 25,000 MPa·μm or less.

[0077] The value of Y represented by the following formula of the chemically strengthened glass according to this embodiment is preferably 10 or more, and more preferably 10 to 50: Y = 0.1 × α - 0.05 × CT ａｖｅ In the above formula, α and CT ａｖｅ is expressed by the following formula: α = 200 × K1c - 100 CT ａｖｅ =I ＣＴ / L ＣＴ Here, I ＣＴ is the integral value of tensile stress (MPa μm), L ＣＴ is the length of the tensile stress region in the thickness direction (μm), K1c is the fracture toughness value (MPa m １／２ ) respectively.

[0078] The value of Y indicates durability against deep cracks. From the viewpoint of achieving superior strength in a #60 sandpaper set drop strength test, the value of Y is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more. From the viewpoint of reducing the transmittance of the glass, the value of Y is preferably 50 or less, more preferably 40 or less, and even more preferably 30 or less.

[0079] The compressive stress value CS at a depth of 50 μm from the surface of the chemically strengthened glass according to this embodiment ５０ Here, the average value of the tensile stress CT is preferably 220 MPa or less in order to realize superior strength in the #60 sandpaper set drop strength test. ａｖｅ From the viewpoint of realizing the above compressive stress value CS ５０ is preferably 220 MPa or less, more preferably 200 MPa or less, even more preferably 170 MPa or less, even more preferably 140 MPa or less, and particularly preferably 110 MPa or less. ５０ is preferably 10 MPa or more, more preferably 30 MPa or more, even more preferably 50 MPa or more, and most preferably 80 MPa or more. ５０ The compressive stress value CS at the outermost surface can be adjusted by the molten salt, temperature, time, etc. used in the chemical strengthening treatment. ０ and compressive stress values ​​CS at depths of 50 μm, 100 μm, or 150 μm from the surface. ５０ , C.S. １００ or CS １５０ The same is true for .

[0080] The compressive stress value CS at a depth of 100 μm from the surface of the chemically strengthened glass according to this embodiment １００ is preferably 30 MPa or less, more preferably 0 to 30 MPa. Here, from the viewpoint of preventing spontaneous destruction due to excessive tensile stress, the compressive stress value CS １００ is preferably 30 MPa or less, more preferably 25 MPa or less, even more preferably 20 MPa or less, and even more preferably 15 MPa or less.１００ is preferably 0 MPa or more, more preferably 5 MPa or more, and even more preferably 10 MPa or more.

[0081] The compressive stress value CS at a depth of 150 μm from the surface of the chemically strengthened glass according to this embodiment １５０ is preferably −100 MPa or more, and more preferably −100 to 0 MPa. Here, from the viewpoint of improving the drop strength of a #60 sandpaper set, the compressive stress value CS １５０ is preferably −100 MPa or more, more preferably −80 MPa or more, even more preferably −70 MPa or more, even more preferably −60 MPa or more, and most preferably −50 MPa or more. １５０ is preferably 0 MPa or less, more preferably −10 MPa or less, further preferably −20 MPa or less, and most preferably −30 MPa or less.

[0082] The compressive stress value CS at the outermost surface of the chemically strengthened glass according to this embodiment ０ Here, from the viewpoint of increasing the bending test strength, the compressive stress value CS ０ is preferably 300 MPa or more, more preferably 400 MPa or more, and even more preferably 500 MPa or more. ０ is preferably 700 MPa or less, more preferably 650 MPa or less, and even more preferably 600 MPa or less.

[0083] The compressive stress layer depth DOL of the chemically strengthened glass according to this embodiment is preferably {0.15 × t} μm or more, and more preferably {0.15 × t + 10} μm or more and {0.15 × t + 70} μm or less, where t (μm) is the thickness of the glass. Here, from the viewpoint of preventing cracks when scratches occur on the surface of the chemically strengthened glass, the compressive stress layer depth DOL is preferably {0.15 × t} μm or more, more preferably {0.15 × t + 10} μm or more, even more preferably {0.15 × t + 20} μm or more, and even more preferably {0.15 × t + 25} μm or more. Further, from the viewpoint of improving the productivity of the strengthening process, the compressive stress layer depth DOL is preferably {0.15 × t + 70} μm or less, more preferably {0.15 × t + 50} μm or less, and even more preferably {0.15 × t + 40} μm or less. The compressive stress layer depth DOL can be adjusted by the molten salt, temperature, time, etc. used in the chemical strengthening treatment. In this specification, the compressive stress layer depth (DOL) is the depth at which the surface compressive stress (CS) becomes zero.

[0084] From the viewpoint of improving the falling ball strength and the drop strength, the chemically strengthened glass according to this embodiment preferably has a compressive stress layer in which Li ions are ion-exchanged with Na ions and then Na ions are ion-exchanged with K ions. In this case, a surface compressive stress is imparted to a portion close to the surface of the glass due to the ion exchange of Na ions with K ions, and a deep compressive stress is imparted to a portion deeper than that due to the ion exchange of Li ions with Na ions.

[0085] In chemically strengthened glass to which the surface compressive stress and deep compressive stress as described above are imparted, the depth K-DOL from the surface of the compressive stress layer due to K ions is preferably 3 μm or more, more preferably 3 to 10 μm. Here, from the viewpoint of improving bending strength, the K-DOL is preferably 3 μm or more, more preferably 4 μm or more, even more preferably 5 μm or more, and even more preferably 6 μm or more. Furthermore, from the viewpoint of reducing electrostatic chargeability, the K-DOL is preferably 10 μm or less, more preferably 9 μm or less, even more preferably 8 μm or less, and even more preferably 7 μm or less.

[0086] Na ion concentration [Na] at a depth of 100 μm from the surface of the chemically strengthened glass according to this embodiment １００ is preferably 2.5 mol % or more, and more preferably 2.7 to 5 mol %. Here, from the viewpoint of improving drop strength, the Na ion concentration [Na] １００ is preferably 2.5 mol% or more, more preferably 2.7 mol% or more, even more preferably 3.0 mol% or more, and particularly preferably 3.5 mol% or more. １００ is preferably 5 mol % or less, more preferably 4.5 mol % or less, and even more preferably 4.0 mol % or less.

[0087] Na ion concentration [Na] at a depth of 50 μm from the surface of the chemically strengthened glass according to this embodiment ５０ is preferably 3 mol % or more, and more preferably 3 to 6 mol %. Here, from the viewpoint of drop strength, the Na ion concentration [Na] ５０ is preferably 3 mol% or more, more preferably 3.3 mol% or more, and even more preferably 3.6 mol% or more. ５０ is preferably 6 mol % or less, more preferably 5.5 mol % or less, even more preferably 5.2 mol % or less, and even more preferably 4.9 mol % or less.

[0088] The chemically strengthened glass according to this embodiment has a Na ion concentration [Na] at a depth of 100 μm from the surface. １００ is 2.5 mol% or more, and the compressive stress value CS at a depth of 100 μm from the surface １００ From the viewpoint of improving the drop strength, it is preferable that the compressive strength be 30 MPa or less.

[0089] The chemically strengthened glass according to this embodiment has a Na ion concentration [Na] at a depth of 100 μm from the surface. １００ and the Na ion concentration [Na] at a depth of 50 μm from the surface ５０ Using {[Na] ５０ / [Na] １００} is preferably 1.4 or less, more preferably 1.05 to 1.4. From the viewpoint of improving the efficiency of the manufacturing process, the ratio is preferably 1.4 or less, more preferably 1.35 or less, and even more preferably 1.3 or less. Furthermore, from the viewpoint of improving drop strength, the ratio is preferably 1.05 or more, more preferably 1.1 or more, and even more preferably 1.2 or more.

[0090] <Characteristics and Physical Properties> The Young's modulus of the glass according to this embodiment is preferably 105 GPa or more, more preferably 105 to 130 GPa. From the viewpoint of high strength, the Young's modulus is preferably 105 GPa or more, more preferably 110 GPa or more, and even more preferably 115 GPa or more. Furthermore, from the viewpoint of high strength, the higher the Young's modulus, the more preferable it is, and although there are no particular limitations, it may be, for example, 130 GPa or less. The Young's modulus in this specification can be measured by an ultrasonic method.

[0091] The transmittance of light with a wavelength of 600 nm of the chemically strengthened glass according to this embodiment, converted to a thickness of 0.6 mm, is preferably 80% or more, more preferably 80 to 98%. From the viewpoint of visibility when the chemically strengthened glass is used as a cover glass, the transmittance is preferably 80% or more, more preferably 85% or more, even more preferably 90% or more, and most preferably 95% or more. The higher the transmittance, the better, but it may be, for example, 98% or less. The transmittance can be adjusted by the crystal species, degree of crystallization, and glass composition. If the thickness of the chemically strengthened glass is not 0.6 mm, the transmittance for a thickness of 0.6 mm can be calculated from the measured transmittance using the Lambert-Beer law. In addition, in the case of chemically strengthened glass with a thickness t greater than 0.6 mm, the thickness may be adjusted to 0.6 mm by polishing, etching, or the like, and the value obtained by actually measuring the transmittance may be used.

[0092] The haze value of the chemically strengthened glass according to this embodiment is preferably 0.20% or less, more preferably 0.05 to 0.20%. Here, from the viewpoint of visibility when the chemically strengthened glass is used as a cover glass, particularly a three-dimensionally shaped cover glass, the haze value is preferably 0.20% or less, more preferably 0.17% or less, even more preferably 0.15% or less, even more preferably 0.13% or less, particularly preferably 0.10% or less, and particularly preferably 0.09% or less. The smaller the haze value, the better, but it may be, for example, 0.05% or more. The haze value can be adjusted by the crystal species, degree of crystallization, and glass composition. In this specification, the haze value refers to the value calculated using a C light source and measured in accordance with JIS K 7136:2000, converted into a thickness of 0.7 mm of chemically strengthened glass. Furthermore, if the actual thickness of the chemically strengthened glass is not 0.7 mm, the haze value can be converted into a 0.7 mm thickness equivalent based on the measured value using the Lambert-Beer law. Furthermore, if the plate thickness t is greater than 0.7 mm, the plate thickness of the chemically strengthened glass may be adjusted to 0.7 mm by polishing, etching, or the like, and then the measurement may be performed.

[0093] The chemically strengthened glass according to this embodiment exhibits a high average crack height measured by a sandpaper set drop strength test under the following conditions. Specifically, the average crack height is preferably 60 cm or more, more preferably 80 cm or more, and the higher the average crack height, the better. (Conditions) The test specimen is an electronic device equipped with chemically strengthened glass, or an electronic device simulation structure integrating chemically strengthened glass with a housing holding the chemically strengthened glass. The drop test is performed by dropping the test specimen onto #60 sandpaper with the chemically strengthened glass of the test specimen facing downward. The test specimen is dropped from a height of 15 cm. If the chemically strengthened glass of the test specimen does not break upon dropping, the drop height is increased by 5 cm and the drop process is repeated. The height at which the chemically strengthened glass of the test specimen first breaks is defined as the crack height. The drop test is performed on 10 test specimens, and the average of their crack heights is defined as the average crack height.

[0094] Regarding the fracture toughness value K1c of the chemically strengthened glass according to this embodiment, although it is difficult to measure the fracture toughness value K1c of crystallized glass, it is generally considered to be almost the same as the fracture toughness value K1c of the crystallized glass before and after chemical strengthening treatment. Therefore, the fracture toughness value K1c of the chemically strengthened glass according to this embodiment is set to 1.0 MPa m １／２ More preferably, 1.2 MPa m １／２ More preferably, 1.3 MPa m １／２ More preferably, 1.35 MPa m １／２ The upper limit is not particularly limited, but is, for example, 2.0 MPa m １／２ The following is also acceptable.

[0095] <<Glass-ceramics>> The glass-ceramics according to this embodiment is glass having a crystalline phase, and is the glass before chemical strengthening treatment of the chemically strengthened glass described above in <<Chemically strengthened glass>>.

[0096] As one aspect of the crystallized glass according to this embodiment, the composition satisfies the following in terms of mole percentage based on oxides: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, P ２ O ５ More than 0% and less than 3%, Li ２ O 20-27%, Na ２ O more than 0% and less than 5%, K ２ O 0-1%, MgO 0-2%, CaO 0-2%, SrO 0-1%, ZrO ２ 1-4.2%, SnO ２ 0-1%, Y ２ O ３ Substantially does not contain K ２ O and Na ２ Using the content ratio of O expressed in mole percentage, {[K ２ O] / [Na ２ O} is 0 to 0.3, ２ O ３ , ZrO ２ , B ２ O ３ and P２ O ５ Using the content ratio expressed in mole percentage, [{[Al ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O ５ ]}] is 0.5 to 1.5.

[0097] The crystallized glass according to this embodiment does not show any significant changes in the overall composition of the glass, the crystalline phase such as crystallinity, or the characteristics and physical properties (other than strength) compared to chemically strengthened glass after chemical strengthening treatment, and can be considered to be the same. That is, the composition and crystalline phase of the crystallized glass according to this embodiment are the same as those described in the "composition" and "crystalline phase" in the above "chemically strengthened glass", respectively, and the preferred aspects are also the same.

[0098] Furthermore, the characteristics and physical properties of the crystallized glass according to this embodiment other than the average crack height measured by a #60 sandpaper set drop strength test are the same as those described in the "Characteristics and Physical Properties" section of the "Chemically Tempered Glass" above, and preferred aspects are also the same.

[0099] The fracture toughness value K1c of the crystallized glass according to this embodiment is 1.0 MPa m １／２ More preferably, 1.2 MPa m １／２ More preferably, 1.3 MPa m １／２ More preferably, 1.35 MPa m １／２ The upper limit is not particularly limited, but is, for example, 2.0 MPa m １／２ The fracture toughness value K1c can be adjusted by the crystal species, the degree of crystallization, and the glass composition. ＩＣ can be measured by the pre-crack introduction fracture test method (SEPB method: Single-Edge-Precracked-Beam method) specified in JIS R 1607:2015.

[0100] The peak positions in the X-ray diffraction (XRD) pattern of the surface of the crystallized glass shift before and after chemical strengthening. Specifically, for example, by performing chemical strengthening, the peak positions derived from lithium disilicate crystals shift to a lower angle by approximately 0.02 to 0.10°. This peak shift means that the Li ions that make up the crystalline phase are also ion-exchanged with Na ions. However, this does not significantly affect the physical properties and characteristics other than strength.

[0101] <<Glass>> The glass according to this embodiment is a glass before crystallization suitable for obtaining the crystallized glass described in the above <<Crystalline Glass>>. In one aspect of the glass according to this embodiment, the composition expressed in mole percentage based on oxides satisfies the following: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, P ２ O ５ More than 0% and less than 3%, Li ２ O 20-27%, Na ２ O more than 0% and less than 5%, K ２ O 0-1%, MgO 0-2%, CaO 0-2%, SrO 0-1%, ZrO ２ 1-4.2%, SnO ２ 0-1%, Y ２ O ３ Substantially does not contain K ２ O and Na ２ Using the content ratio of O expressed in mole percentage, {[K ２ O] / [Na ２ O} is 0 to 0.3, ２ O ３ , ZrO ２ , B ２ O ３ and P ２ O ５ Using the content ratio expressed in mole percentage, [{[Al ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O５ ]}] is 0.5 to 1.5.

[0102] The glass according to this embodiment does not show a significant change in the overall composition of the glass compared to the crystallized glass after crystallization, and can be considered the same. Also, as described above, the crystallized glass according to this embodiment does not show a significant change in the overall composition of the glass compared to the chemically strengthened glass after chemical strengthening treatment, and can be considered the same. That is, the composition of the glass according to this embodiment is the same as that described in the "Composition" in the above "Chemically Strengthened Glass", and the preferred aspects are also the same.

[0103] <<Applications>> The chemically strengthened glass according to this embodiment is useful as a cover glass for electronic devices such as mobile phones and smartphones. It is also useful as a cover glass for non-portable electronic devices such as televisions, personal computers, and touch panels, as well as elevator walls and wall surfaces (full-surface displays) of buildings such as houses and buildings. It is also useful as building materials such as window glass, tabletops, interiors of automobiles and airplanes, and their cover glass, as well as for curved housings. Furthermore, the crystallized glass according to this embodiment becomes very useful for each of the above applications by undergoing a chemical strengthening treatment. Furthermore, the glass according to this embodiment becomes very useful for each of the above applications by undergoing a crystallization treatment and a chemical strengthening treatment.

[0104] <<Methods for producing glass, crystallized glass, and chemically strengthened glass>> The glass according to this embodiment can be produced by blending raw materials to obtain a desired composition and using a conventionally known method. That is, the method for producing glass according to this embodiment includes the following step 1. The crystallized glass according to this embodiment can be produced by heat-treating amorphous glass to crystallize it. That is, the method for producing crystallized glass according to this embodiment includes the following steps 1 and 2. The chemically strengthened glass according to this embodiment can be produced by chemically strengthening the crystallized glass. That is, the method for producing chemically strengthened glass according to this embodiment includes the following steps 1 to 3.

[0105] Step 1: A step of producing amorphous glass. Step 2: A step of crystallizing the amorphous glass obtained in step 1 to obtain crystallized glass. Step 3: A step of chemically strengthening the crystallized glass obtained in step 2 to obtain chemically strengthened glass.

[0106] Each step will be described below.

[0107] <Step 1> Step 1 is a step of producing amorphous glass, and a conventionally known method can be used as the specific method. That is, when obtaining amorphous glass, for example, glass raw materials are blended to obtain a desired composition and heated and melted in a glass melting furnace. The molten glass is then homogenized by bubbling, stirring, adding a fining agent, etc., formed into a desired shape by a known forming method, and slowly cooled. Alternatively, the molten glass may be formed into a block, slowly cooled, and then cut and processed into a desired shape. Examples of glass forming methods include the float method, the press method, the fusion method, and the downdraw method. Examples of slowly cooling methods include a method of cooling to room temperature at a rate of 0.1 to 2°C / min. The slowly cooling may be performed by holding the glass at a specific temperature for a specific time and then cooling to room temperature. Specifically, for example, the glass may be held at 420 to 550°C for 10 to 180 minutes and then cooled to room temperature at a rate of 0.1 to 2°C / min.

[0108] The desired composition is the same as the preferred embodiment described in the <Composition> section of the <<Chemically strengthened glass>> above.

[0109] <Step 2> Step 2 is a step of obtaining crystallized glass by crystallizing the amorphous glass obtained in step 1. This results in crystallized glass having a crystalline phase and a desired composition.

[0110] The heat treatment for crystallization is not particularly limited as long as it produces the desired crystals, but may be, for example, a two-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. After the two-stage heat treatment, a three-stage heat treatment may be performed in which the temperature is maintained at a third treatment temperature for a certain period of time. Alternatively, a one-stage heat treatment in which the temperature is maintained at a specific treatment temperature and then cooled to room temperature may be performed.

[0111] 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 for the glass composition, and the second treatment temperature is preferably in a temperature range where the crystal growth rate is high for the glass composition.

[0112] In the case of a three-stage heat treatment, it is preferable that the first and second treatment temperatures are temperatures at which the crystal nucleation rate increases, and the third treatment temperature is a temperature at which the crystal growth rate increases. Alternatively, the first treatment temperature may be a temperature at which the crystal nucleation rate increases, and the second and third treatment temperatures may be temperatures at which the crystal growth rate increases.

[0113] In the two-stage heat treatment and the three-stage heat treatment, the holding time at the first treatment temperature is preferably long enough to generate a sufficient number of crystal nuclei. The generation of a large number of crystal nuclei reduces the size of each crystal, resulting in a highly transparent crystallized glass.

[0114] More specifically, in the case of a two-stage treatment, for example, the first treatment temperature is held at 500°C to 700°C for 1 hour to 6 hours, and then the second treatment temperature is held at 600°C to 800°C for 1 hour to 6 hours.

[0115] More specifically, in the case of a three-stage treatment, for example, after holding at a first treatment temperature of 450°C to 600°C for 1 hour to 6 hours, for example, at a second treatment temperature of 500°C to 650°C for 1 hour to 6 hours, and further, for example, at a third treatment temperature of 600°C to 800°C for 1 hour to 6 hours.

[0116] More specifically, in the case of a one-stage treatment, the temperature may be maintained at 500° C. to 800° C. for 1 hour to 6 hours.

[0117] The crystallized glass obtained in step 2 may be ground and polished as necessary. When the crystallized glass obtained is cut to a predetermined shape and size or chamfered, it is preferable to perform the cutting or chamfering before performing the chemical strengthening treatment in the next step 3. This allows a compressive stress layer to be formed on the cut surface or the chamfered surface by the subsequent chemical strengthening treatment.

[0118] <Step 3> Step 3 is a step of obtaining chemically strengthened glass by performing a chemical strengthening treatment on the crystallized glass obtained in step 2. The chemical strengthening treatment is a treatment in which the glass is brought into contact with a metal salt (e.g., potassium nitrate) containing a metal ion with a large ionic radius (typically, Na ion or K ion) by, for example, immersing the glass in a melt of the metal salt, thereby replacing the metal ion with a small ionic radius (typically, Li ion or Na ion) with a metal ion with a large ionic radius (typically, Na ion or K ion for Li ion, and K ion for Na ion).

[0119] To increase the speed of chemical strengthening, it is preferable to use "Li-Na exchange," which exchanges Li ions in the glass with Na ions. Here, the crystallized glass in this embodiment contains a crystalline phase, but a compressive stress layer is formed not only in the amorphous phase but also when Li constituting the crystalline phase is converted to Na.

[0120] In order to form a larger compressive stress by ion exchange, it is preferable to use "Na-K exchange" in which Na ions in the glass are exchanged with K ions.

[0121] Examples of molten salts for chemical strengthening include nitrates, sulfates, carbonates, and chlorides. Examples of nitrates include lithium nitrate, sodium nitrate, potassium nitrate, cesium nitrate, and silver nitrate. Examples of sulfates include lithium sulfate, sodium sulfate, potassium sulfate, cesium sulfate, and silver sulfate. Examples of carbonates include lithium carbonate, sodium carbonate, and potassium carbonate. Examples of chlorides include lithium chloride, sodium chloride, potassium chloride, cesium chloride, and silver chloride. These molten salts may be used alone or in combination.

[0122] When both the Li—Na exchange and the Na—K exchange are carried out, for example, a mixed molten salt of lithium nitrate, sodium nitrate, and potassium nitrate may be used. In this case, the mixing ratio of lithium nitrate, sodium nitrate, and potassium nitrate is not particularly limited, but for example, the lithium nitrate is preferably 0.002 to 0.5 parts by mass, the sodium nitrate is preferably 20 to 70 parts by mass, and the potassium nitrate is preferably 30 to 80 parts by mass, per 100 parts by mass of the total of lithium nitrate, sodium nitrate, and potassium nitrate.

[0123] The conditions for the chemical strengthening treatment, such as time and temperature, can be selected taking into consideration the glass composition, the type of molten salt, etc. For example, the crystallized glass obtained in step 2 can be chemically strengthened at preferably 500°C or less for preferably 20 hours or less. Alternatively, two or more stages of chemical strengthening treatment may be performed.

[0124] The present invention will be described below with reference to test examples, but the present invention is not limited thereto. Examples 1 to 4 are working examples, and Examples 5 to 8 are comparative examples.

[0125] Examples 1 to 8 Glass raw materials were blended to obtain the glass compositions (glass materials A to G) shown in Table 1 in mole percent based on oxides, and weighed to obtain 600 g of glass. The mixed glass raw materials were then placed in a platinum crucible and placed in an electric furnace at 1550°C, where they were melted for approximately 5 hours, degassed, and homogenized. The resulting molten glass was poured into a mold, held at 470°C for 1 hour, and then cooled to room temperature at a rate of 0.5°C / min to obtain a glass block. Note that blanks in the glass composition columns in Table 1 indicate that no additives were added.

[0126] The obtained glass blocks were each processed into plates measuring 50 mm x 50 mm x 0.6 mm thick, and subjected to a two- or three-stage crystallization treatment. Specifically, the first and second treatments, or the first, second and second treatments, were performed at the temperatures and holding times listed under "Crystallization Conditions" in Table 1. The blocks were then cooled to room temperature to obtain crystallized glass. Note that the "-" mark in the "Crystallization Conditions" section of Table 1 indicates that the third heat treatment was not performed.

[0127] The obtained crystallized glass was subjected to ion exchange treatment using the molten salt, at the temperature, and for the time shown in the "Toughening Conditions" section of Table 2, to obtain chemically strengthened glass.

[0128] <Evaluation> <Transmittance> The transmittance of the crystallized glass was measured using a spectrophotometer (product name U-4100) manufactured by Hitachi High-Tech Corporation. Specifically, the transmittance of light with a wavelength of 600 nm was determined. The thickness of the crystallized glass was 0.6 mm. The results are shown in Table 2.

[0129] <X-ray diffraction: precipitated crystals> Powder X-ray diffraction was measured for the crystallized glass under the following conditions, and the crystallization rate, precipitated crystals, and their content ratio were determined by Rietveld analysis. The results are shown in Table 1, but only the main crystal species is listed for the crystalline phase. Here, the main crystal species refers to the type of crystal with the highest content ratio among the crystals that make up the crystalline phase. Measuring device: SmartLab manufactured by Rigaku Corporation X-ray used: Cu-Kα ray Measuring range: 2θ = 10° to 80° Speed: 10° / min Step: 0.02°

[0130] <Composition> Composition analysis of the obtained glass-ceramics and chemically strengthened glass confirmed that there was no significant change from the glass composition before crystallization and that it was the same as the glass composition shown in Table 1. Therefore, although "composition" is shown in Table 1, this represents the composition of the entire amorphous glass before crystallization, the glass-ceramics, and the chemically strengthened glass after the glass-ceramics was chemically strengthened at the center in the thickness direction.

[0131] <Young's modulus> The Young's modulus of the crystallized glass was measured by an ultrasonic method using an ultrasonic thickness gauge (manufactured by Olympus Corporation, product name 38DL). The results are shown in Table 1. It was confirmed that the Young's modulus of the chemically strengthened glass after chemical strengthening treatment was also comparable to that of the crystallized glass.

[0132] <Fracture toughness value K1c> Fracture toughness value K of crystallized glass ＩＣ was measured using a strength testing machine (Shimadzu Corporation, Autograph AGS-X) according to the SEPB method (Single-Edge-Precracked-Beam method) specified in JIS R1607:2015. The results for the glass-ceramics are shown in Table 1. The fracture toughness value K for the chemically strengthened glass was also measured. ＩＣ Although the fracture toughness value K is not measured, it is the same as that of glass-ceramics. ＩＣ The values ​​are shown in parentheses in Table 2.

[0133] <Stress Profile> The stress profile in the depth direction of the chemically strengthened glass was measured using a measuring instrument SLP-2000 manufactured by Orihara Manufacturing Co., Ltd. Based on the stress profile, the compressive stress value CS at a depth of 50 μm from the surface was calculated. ５０ (MPa), compressive stress value CS at a depth of 100 μm from the surface １００ (MPa), compressive stress value CS at a depth of 150 μm from the surface １５０ (MPa), compressive stress layer depth DOL (μm), depth from the surface of the compressive stress layer due to K ions K-DOL (μm), maximum tensile stress CT ｍａｘ (MPa), and the integral value I of the tensile stress ＣＴ (MPa μm) and the thickness direction length L of the tensile stress region ＣＴAverage value of tensile stress CT obtained from (μm) ａｖｅ (MPa) are shown in Table 2. The average value of the tensile stress CT ａｖｅ The values ​​of α and Y, which are evaluation parameters calculated using the fracture toughness value K1c (MPa) and the above-mentioned fracture toughness value K1c according to the following formula, are also shown in Table 2: Y = 0.1 × α - 0.05 × CT ａｖｅ α=200×K1c-100 CT ａｖｅ =I ＣＴ / L ＣＴ I ＣＴ : Integrated value of tensile stress (MPa μm) L ＣＴ : Length of tensile stress region in the plate thickness direction (μm) K1c: Fracture toughness value (MPa m １／２ )

[0134] <Na ion concentration> Na ion concentration at a depth of 100 μm from the surface in chemically strengthened glass [Na] １００ and the Na ion concentration at a depth of 50 μm from the surface [Na] ５０ was obtained by analysis using an electron probe microanalyzer (EPMA). In this embodiment, the Na profile in the thickness direction of the chemically strengthened crystallized glass was obtained by the following method. First, the chemically strengthened glass was embedded in resin, a cross section was prepared on a plane parallel to the thickness direction of the chemically strengthened glass, and the cross section was mirror-polished to obtain a measurement sample. The surface of the cross section of the chemically strengthened glass of the obtained measurement sample was analyzed by EPMA. For the EPMA analysis, a JXA-8500F manufactured by JEOL was used. In the EPMA analysis, a line scan analysis was performed along the thickness direction of the chemically strengthened glass of the measurement sample. The results are shown in Table 2. Table 2 also shows [Na] ５０ [Na] １００ In addition to each value of {[Na] ５０ / [Na] １００ The chemically strengthened glass of Example 7 was not measured, and therefore is shown as "-" in Table 2.

[0135] <#60 Sandpaper Set Drop Strength> As an electronic device simulation structure, a 50 mm x 50 mm x 0.6 mm thick chemically strengthened glass (4 g) was attached to a 70 mm x 70 mm x 2 mm thick aluminum plate (26 g) using 30 mm x 30 mm double-sided tape to create a test specimen with a total weight of 31 g. The double-sided tape used was a differential type removable double-sided tape (Double Face (registered trademark) DF8350, manufactured by Toyochem Co., Ltd.) with strong and weak adhesive properties. The test specimen was placed in the device with the chemically strengthened glass facing downward and dropped onto #60 sandpaper. The test specimen was dropped from a height of 15 cm. If the chemically strengthened glass did not break, the drop height was increased by 5 cm and the drop process was repeated. The height at which the chemically strengthened glass first broke in the test specimen was recorded as the crack height. For each test example, the drop test was performed on 10 test specimens, and the average of the crack heights was recorded as the average crack height. The results are shown in Table 2.

[0136]

[0137]

[0138] From the above results, it can be seen that the chemically strengthened glass according to this embodiment has a high fracture toughness value K1c and a low average tensile stress CT by satisfying a specific composition range. ａｖｅ As a result, high strength characteristics were achieved in a #60 sandpaper set drop strength test.

[0139] 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 Japanese patent applications filed on June 7, 2024 (Patent Application No. 2024-092882), December 24, 2024 (Patent Application No. 2024-227177), and March 31, 2025 (Patent Application No. 2025-058529), the contents of which are incorporated herein by reference.

Claims

1. It is a crystallized glass with a crystalline phase, and the composition of the center of the thickness direction is expressed as mole percentage based on oxides: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, P ２ O ５ More than 0% and less than 3%, Li ２ O 20-27%, Na ２ O more than 0% and less than 5%, K ２ O 0-1%, MgO 0-2%, CaO 0-2%, SrO 0-1%, ZrO ２ 1 to 4.2%, and SnO ２ 0 to 1%, Y ２ O ３ Substantially does not contain K ２ O and Na ２ Using the content ratio of O expressed in mole percentage, {[K ２ O] / [Na ２ O} is 0 to 0.3, ２ O ３ , ZrO ２ , B ２ O ３ and P ２ O ５ Using the content ratio expressed in mole percentage, [{[Al ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O ５ ]}] is 0.5 to 1.

5.

2. It is a crystallized glass with a crystalline phase, and the composition of the center of the thickness direction is expressed as mole percentage based on oxides: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, Li ２ O 20-27%, and ZrO ２ 1 to 4.2%, and the integral value of the tensile stress I ＣＴ (MPa μm) and the thickness direction length L of the tensile stress region ＣＴ (μm), {I ＣＴ / L ＣＴ } The average value of the tensile stress CT ａｖｅ Chemically strengthened glass, wherein the strength is 60 MPa or less.

3. The crystalline phase is Li ２ Si ２ O ５ , LiAlSi ２ O ６ , LiAlSi ４ O １０ , Li ３ P.O. ４ The chemically strengthened glass according to claim 1 or 2, comprising at least one crystal selected from the group consisting of β-quartz solid solution.

4. Fracture toughness value K1c is 1.3 MPa m １／２ The chemically strengthened glass according to claim 1 or 2.

5. Integral value of tensile stress I ＣＴ (MPa μm) and the thickness direction length L of the tensile stress region ＣＴ (μm), {I ＣＴ / L ＣＴ } The average value of the tensile stress CT ａｖｅ The chemically strengthened glass according to claim 1, wherein the compressive strength is 60 MPa or less.

6. Compressive stress value CS at a depth of 50 μm from the surface ５０ The chemically strengthened glass according to claim 1 or 2, wherein the compressive strength is 220 MPa or less.

7. Compressive stress value CS at a depth of 150 μm from the surface １５０ The chemically strengthened glass according to claim 1 or 2, wherein the strain is −100 MPa or more.

8. The chemically strengthened glass according to claim 1 or 2, wherein the value of Y represented by the following formula is 10 or more: Y = 0.1 × α - 0.05 × CT ａｖｅ α=200×K1c-100 CT ａｖｅ =I ＣＴ / L ＣＴ I ＣＴ : Integrated value of tensile stress (MPa μm) L ＣＴ : Length of tensile stress region in the plate thickness direction (μm) K1c: Fracture toughness value (MPa m １／２ ) 9. The chemically strengthened glass according to claim 1 or 2, wherein the depth (K-DOL) from the surface of the compressive stress layer due to K ions is 3 μm or more.

10. The chemically strengthened glass according to claim 1 or 2, wherein the compressive stress layer depth DOL is 100 μm or more.

11. The chemically strengthened glass according to claim 1 or 2, wherein the compressive stress layer depth DOL is {t × 0.15} μm or greater, where t (μm) is the thickness of the glass.

12. Na ion concentration at a depth of 100 μm from the surface [Na] １００ is 2.5 mol% or more, and the compressive stress value CS at a depth of 100 μm from the surface １００ The chemically strengthened glass according to claim 1 or 2, wherein the compressive strength is 30 MPa or less.

13. Na ion concentration at a depth of 100 μm from the surface [Na] １００ and the Na ion concentration at a depth of 50 μm from the surface [Na] ５０ Using {[Na] ５０ / [Na] １００ The chemically strengthened glass according to claim 1 or 2, wherein the ratio represented by {} is 1.4 or less.

14. Compressive stress value CS at the outermost surface ０ The chemically strengthened glass according to claim 1 or 2, wherein the compressive strength is 300 to 700 MPa.

15. The chemically strengthened glass according to claim 1 or 2, having a Young's modulus of 105 GPa or more.

16. The chemically strengthened glass according to claim 1 or 2, wherein the average crack height measured by a sandpaper set drop strength test under the following conditions is 40 cm or more. (Conditions) The test specimen is an electronic device equipped with chemically strengthened glass, or an electronic device simulation structure in which chemically strengthened glass is integrated with a housing that holds the chemically strengthened glass. The drop test is conducted by dropping the test specimen, with the chemically strengthened glass of the test specimen facing downward, onto #60 sandpaper. The test specimen is dropped from a height of 15 cm. If the chemically strengthened glass of the test specimen does not break upon dropping, the drop height is increased by 5 cm increments and the drop process is repeated. The height at which the chemically strengthened glass of the test specimen first breaks is defined as the crack height. The drop test is conducted on 10 test specimens, and the average of their crack heights is defined as the average crack height.

17. Al ２ O ３ and Na ２ Using the content ratio of O expressed in mole percentage, {[Al ２ O ３ ] / [Na ２ The chemically strengthened glass according to claim 1 or 2, wherein the value represented by {R(t)} is greater than 0 and not greater than 2.

3.

18. Li ２ O and ZrO ２ Using the content ratio expressed in mole percentage, {[Li ２ O] / [ZrO ２ 3. The chemically strengthened glass according to claim 1 or 2, wherein a value represented by {overscore (R)} is 8 or more.

19. Chemically strengthened glass according to claim 1 or 2, having a crystallization rate of 40 mass% or more.

20. The chemically strengthened glass according to claim 1 or 2, wherein the average grain size of the crystals constituting the crystalline phase is 10 to 100 nm.

21. The chemically strengthened glass according to claim 1 or 2, which has a transmittance of 80% or more for light with a wavelength of 600 nm when converted into a glass with a thickness of 0.6 mm.

22. A crystallized glass having a crystalline phase, the composition of which is expressed in mole percentage based on oxides: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, P ２ O ５ More than 0% and less than 3%, Li ２ O 20-27%, Na ２ O more than 0% and less than 5%, K ２ O 0-1%, MgO 0-2%, CaO 0-2%, SrO 0-1%, ZrO ２ 1 to 4.2%, and SnO ２ 0 to 1%, Y ２ O ３ Substantially does not contain K ２ O and Na ２ Using the content ratio of O expressed in mole percentage, {[K ２ O] / [Na ２ O} is 0 to 0.3, ２ O ３ , ZrO ２ , B ２ O ３ and P ２ O ５ Using the content ratio expressed in mole percentage, [{[Al ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O ５ ]}] is 0.5 to 1.

5.

23. The crystalline phase is Li ２ Si ２ O ５ , LiAlSi ２ O ６ , LiAlSi ４ O １０ , Li ３ P.O. ４ 23. The crystallized glass according to claim 22, comprising at least one crystal selected from the group consisting of: and β-quartz solid solution.

24. The fracture toughness value K1c is 1.2 MPa·m １／２ The crystallized glass according to claim 22 or 23, wherein 25. The crystallized glass according to claim 22 or 23, having a Young's modulus of 105 GPa or more.

26. Al ２ O ３ and Na ２ Using the content ratio of O expressed in mole percentage, {[Al ２ O ３ ] / [Na ２ 24. The crystallized glass according to claim 22 or 23, wherein the value represented by [Ratio of % to %] is greater than 0 and not greater than 0.

23.

27. Li ２ O and ZrO ２ Using the content ratio expressed in mole percentage, {[Li ２ O] / [ZrO ２ 24. The crystallized glass according to claim 22, wherein the value represented by {overscore (R)} is 8 or more.

28. The crystallized glass according to claim 22 or 23, having a crystallization rate of 40% by mass or more.

29. The crystallized glass according to claim 22 or 23, wherein the average grain size of the crystals constituting the crystalline phase is 10 to 100 nm.

30. Crystallized glass according to claim 22 or 23, which has a transmittance of 80% or more for light with a wavelength of 600 nm when converted into a glass with a thickness of 0.6 mm.

31. The composition is expressed as mole percentage based on oxides: SiO ２ 62-75%, Al ２ O ３ 2.2-6.0%, P ２ O ５ More than 0% and less than 3%, Li ２ O 20-27%, Na ２ O more than 0% and less than 5%, K ２ O 0-1%, MgO 0-2%, CaO 0-2%, SrO 0-1%, ZrO ２ 1 to 4.2%, and SnO ２ 0 to 1%, Y ２ O ３ Substantially does not contain K ２ O and Na ２ Using the content ratio of O expressed in mole percentage, {[K ２ O] / [Na ２ O} is 0 to 0.3, ２ O ３ , ZrO ２ , B ２ O ３ and P ２ O ５ Using the content ratio expressed in mole percentage, [{[Al ２ O ３ ] / [ZrO ２ ]-{[B ２ O ３ ] / [P ２ O ５ ]}] is 0.5 to 1.

5.

32. Al ２ O ３ and Na ２ Using the content ratio of O expressed in mole percentage, {[Al ２ O ３ ] / [Na ２ 32. The glass of claim 31 , wherein the value of {O} is greater than 0 and less than or equal to 0.

23.

33. Li ２ O and ZrO ２ Using the content ratio expressed in mole percentage, {[Li ２ O] / [ZrO ２ 33. The glass according to claim 31 or 32, wherein the value represented by {R(x,y)} is 8 or greater.

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