Inorganic composition product

Abstract

The invention relates to an inorganic composition product which is formed by strengthening crystallized glass. The crystallized glass contains, as a main crystal phase, one or more substances selected from the group consisting of alpha-cristobalite and alpha-cristobalite solid solutions. The content of the SiO2 component is 50.0% to 75.0%, the content of the Li2O component is 3.0% to 10.0%, the content of the Al2O3 component is 5.0% to less than 15.0%, the content of the B2O3 component is more than 0% to 10.0% (inclusive), and the content of the P2O5 component is more than 0% to 10.0% (inclusive) in terms of mass% of oxides; the mass ratio of SiO2 / (B2O3 + Li2O) is from 3.0 to 10.0; the inorganic composition product has a compressive stress layer on the surface and has a four-point bending strength of 760 MPa or more.

Description

Technical Field

[0001] The present invention relates to an inorganic composition product related to strengthened crystallized glass having a compressive stress layer on the surface. Background Art

[0002] Various glass types are expected to be used in the field as cover glass and housings for display protection of portable electronic devices such as smartphones and tablet PCs (Personal Computers), as well as lens protectors for automotive optical devices, interior trims, console panels, touch panel materials, and smart keys. Furthermore, these devices are required to operate in harsh environments, and the demand for higher-strength glass is increasing.

[0003] Chemically strengthened glass has traditionally been used for protective components and other applications. However, this conventional chemically strengthened glass poses a problem: portable devices such as smartphones often break when dropped. This requires high-strength, crystallized glass that resists breakage when dropped.

[0004] High strength tends to be less prone to breakage, but on the other hand, there is sometimes a need for higher impact resistance when dropped. Since the thickness of the compressive stress layer (DOLzero (μm)) and the compressive stress (CS) (MPa) contribute to impact resistance, glass with high strength and desired DOLzero (μm) and compressive stress (CS) (MPa) is sought.

[0005] Patent Document 1 discloses the material composition of a chemically strengthened crystallized glass substrate for information recording media. The α-cristobalite crystallized glass described in Patent Document 1 is said to be chemically strengthened and can be used as a high-strength substrate. However, crystallized glass for information recording media, such as hard disk substrates, is not intended for use in harsh environments.

[0006] Patent Document 2 discloses a glass-ceramic product having excellent mechanical properties and a main crystal phase including lithium silicate and a quartz crystal phase. However, the product is not expected to have the strength to withstand a harsh environment.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2008-254984

[0010] Patent Document 2: Japanese Patent Application No. 2021-520330 Summary of the Invention

[0011] The object of the present invention is to provide an inorganic composition product related to tempered crystallized glass that is not easily broken when dropped, has high strength, and has a desired DOLzero (μm) and compressive stress CS (MPa).

[0012] The present invention provides the following configurations.

[0013] [Composition 1]

[0014] An inorganic composition product made by strengthening crystallized glass;

[0015] The crystallized glass contains one or more selected from α-cristobalite and α-cristobalite solid solution as the main crystalline phase;

[0016] Calculated in mass % of oxide conversion:

[0017] The content of SiO2 component is 50.0% to 75.0%;

[0018] The content of Li2O component is 3.0% to 10.0%;

[0019] The content of Al2O3 component is 5.0% or more and less than 15.0%;

[0020] The content of B2O3 is greater than 0% and less than 10.0%;

[0021] The content of P2O5 is greater than 0% and less than 10.0%;

[0022] The mass ratio SiO2 / (B2O3+Li2O) is 3.0 to 10.0;

[0023] The inorganic composition product has a compressive stress layer on the surface and has a four-point bending strength of 760 MPa or more.

[0024] [Composition 2]

[0025] The inorganic composition product according to configuration 1, wherein the crystallized glass is expressed in mass % as oxides:

[0026] The content of ZrO2 is greater than 0% and less than 10.0%;

[0027] The total content of Al2O3 and ZrO2 components is 10.0% or more.

[0028] [Composition 3]

[0029] The inorganic composition product according to configuration 1 or configuration 2, wherein the crystallized glass is expressed in mass % as oxides:

[0030] The content of K2O component is 0% to 5.0%.

[0031] [Composition 4]

[0032] The inorganic composition product according to any one of Configurations 1 to 3, wherein the crystallized glass is expressed in mass % as oxides:

[0033] The content of Na2O component is 0% to 4.0%;

[0034] The content of MgO component is 0% to 4.0%;

[0035] The content of CaO component is 0% to 4.0%;

[0036] The content of SrO component is 0% to 4.0%;

[0037] The content of BaO component is 0% to 5.0%;

[0038] The content of ZnO component is 0% to 10.0%;

[0039] The content of Sb2O3 component is 0% to 3.0%.

[0040] [Composition 5]

[0041] The inorganic composition product according to any one of Configurations 1 to 4, wherein the crystallized glass is expressed in mass % as oxides:

[0042] The content of Nb2O5 component is 0% to 5.0%;

[0043] The content of Ta2O5 component is 0% to 6.0%;

[0044] The content of the TiO2 component is from 0% to less than 1.0%.

[0045] [Composition 6]

[0046] The inorganic composition product according to any one of Configurations 1 to 5, wherein the glass transition temperature Tg of the crystallized glass before crystallization is 610° C. or lower.

[0047] [Composition 7]

[0048] The inorganic composition product according to any one of Configurations 1 to 6, wherein [compressive stress CS (MPa)]×[thickness of the compressive stress layer DOLzero (μm)] / [thickness of the substrate t (mm)] is 100 to 350.

[0049] According to the present invention, by controlling the amount of LiO2 and adjusting the amounts of SiO2 and Al2O3, it is possible to easily and stably manufacture an inorganic composition product related to crystallized glass with high impact resistance. Furthermore, it is possible to provide an inorganic composition product with high strength and desired DOLzero (μm) and compressive stress CS (MPa).

[0050] The "inorganic composition product" (hereinafter referred to as "product") in the present invention is composed of inorganic composition materials such as glass, crystallized glass, ceramics, or composite materials thereof. For example, products obtained by molding these inorganic materials into a desired shape through processing, synthesis using chemical reactions, etc. are consistent with the products of the present invention. In addition, pressurized powders obtained by crushing inorganic materials and then pressurizing them, sintered bodies obtained by sintering pressurized powders, etc. also meet the requirements. There are no restrictions on the shape, smoothness, curvature, size, etc. of the product obtained here. For example, it can be a plate-like substrate, a molded body with curvature, or a three-dimensional structure with a complex shape. In addition, products obtained by chemically strengthening inorganic composition materials also meet the requirements.

[0051] The inorganic composition product of the present invention can be effectively utilized as a high-strength glass-based material for use in protective components for devices. It can be used as cover glass and housings for smartphones, components for portable electronic devices such as tablet PCs and wearable devices, as well as components such as protectors and head-up display substrates used in transportation vehicles such as cars and airplanes. It can also be used in other electronic devices, machinery and equipment, architectural components, solar panel components, projector components, and cover glass (windproof) for eyeglasses and clocks. DETAILED DESCRIPTION

[0052] Hereinafter, embodiments and examples of the inorganic composition product of the present invention will be described in detail. However, the present invention is not limited to the following embodiments and examples, and can be implemented with appropriate modifications within the scope of the purpose of the present invention.

[0053] The inorganic composition product of the present invention and the crystallized glass serving as the base material of the product contain one or more selected from α-cristobalite and α-cristobalite solid solutions as the main crystalline phase. The crystallized glass precipitated with these crystalline phases has high mechanical strength.

[0054] The "main crystalline phase" in this specification corresponds to the crystalline phase that is most abundant in the crystallized glass as determined by the peaks of the X-ray diffraction pattern.

[0055] In this specification, unless otherwise specified, the content of each component is expressed in mass % of oxide conversion. Here, "oxide conversion" refers to the amount of each component's oxide contained in the crystallized glass, expressed in mass %, assuming that all components of the crystallized glass are decomposed and converted into oxides, with the total mass of the oxides being 100 mass %. In this specification, "A% to B%" means greater than A% and less than B%.

[0056] Hereinafter, the inorganic composition product according to the first embodiment of the present invention will be described.

[0057] The tempered crystallized glass of the inorganic composition product according to the first embodiment of the present invention and the crystallized glass serving as the base material of the product are expressed in terms of oxide mass %:

[0058] The content of SiO2 component is 50.0% to 75.0%;

[0059] The content of Li2O component is 3.0% to 10.0%;

[0060] The content of Al2O3 component is 5.0% or more and less than 15.0%;

[0061] The content of B2O3 is greater than 0% and less than 10.0%;

[0062] The content of P2O5 is greater than 0% and less than 10.0%;

[0063] Furthermore, the mass ratio SiO2 / (B2O3+Li2O) is 3.0 to 10.0.

[0064] By having the above-mentioned composition, strengthening by chemical strengthening is possible, and thus it is possible to provide a tempered crystallized glass having high strength and desired DOLzero (μm) and compressive stress CS (MPa).

[0065] Hereinafter, the composition range of each component constituting the crystallized glass serving as the base material of the present invention will be specifically described.

[0066] The SiO2 component is an essential component for forming one or more selected from α-cristobalite and an α-cristobalite solid solution. If the SiO2 content is 75.0% or less, an excessive increase in viscosity and a deterioration in solubility can be suppressed. On the other hand, if the SiO2 content is 50.0% or more, deterioration in devitrification can be suppressed.

[0067] The upper limit is preferably set to 74.0% or less, 73.0% or less, 72.0% or less, or 70.0% or less, and the lower limit is preferably set to 55.0% or more, 58.0% or more, or 60.0% or more.

[0068] The Li2O component improves the meltability of the raw glass. When the Li2O content is 3.0% or more, the meltability of the raw glass can be improved. Furthermore, when the Li2O content is 10.0% or less, the increase in the formation of lithium disilicate crystals can be suppressed. Furthermore, the Li2O component is involved in chemical strengthening.

[0069] The lower limit is preferably 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, or 5.5% or more, and the upper limit is preferably 9.0% or less, for example, 8.5% or less, or 8.0% or less.

[0070] Al2O3 is a suitable component for improving the mechanical strength of crystallized glass. If the content of Al2O3 is less than 15.0%, deterioration of solubility and devitrification can be suppressed. In addition, if it is 5.0% or more, reduction in mechanical strength can be suppressed.

[0071] The upper limit is preferably set to 14.5% or less, 14.0% or less, 13.5% or less, or 13.0% or less. The lower limit may be set to 5.5% or more, 5.8% or more, 6.0% or more, 6.5% or more, or 8.0% or more.

[0072] The B 2 O 3 component is a component suitable for lowering the glass transition temperature of crystallized glass. If the amount of the B 2 O 3 component is set to 10.0% or less, a decrease in chemical durability can be suppressed.

[0073] The upper limit is preferably 8.0% or less, 7.0% or less, 5.0% or less, or 4.0% or less. The lower limit is greater than 0%, and is preferably 0.001% or more, 0.01% or more, 0.05% or more, 0.10% or more, or 0.30% or more.

[0074] The ZrO 2 component is a component that can improve mechanical strength. If the amount of the ZrO 2 component is 10.0% or less, deterioration of solubility can be suppressed.

[0075] The upper limit is preferably set to 10.0% or less, 9.0% or less, 8.5% or less, or 8.0% or less. The lower limit may preferably be set to greater than 0%, 1.0% or more, 1.5% or more, or 2.0% or more.

[0076] If the sum of the contents of Al2O3 and ZrO2 [Al2O3 + ZrO2] is high, the surface compressive stress will increase during strengthening. Preferably, the lower limit of [Al2O3 + ZrO2] is set to 10.0% or more, 11.0% or more, 12.0% or more, or 13.0% or more.

[0077] On the other hand, by setting it to 22.0% or less, deterioration of solubility can be suppressed. Therefore, the upper limit of [Al2O3+ZrO2] is preferably set to 22.0% or less, 21.0% or less, 20.0% or less, or 19.0% or less.

[0078] The mass ratio SiO2 / (B2O3+Li2O) is 3.0 to 10.0. Setting this mass ratio to 3.0 to 10.0 can help reduce the viscosity of the glass, making it easier to manufacture the glass. Furthermore, it can increase the amount of alkali ions that undergo ion exchange during chemical strengthening, thereby producing a desired CS30 (compressive stress at a depth of 30 μm from the outermost surface) strengthened crystallized glass.

[0079] Therefore, the lower limit of the mass ratio SiO2 / (B2O3+Li2O) is preferably set to 3.5 or more, and more preferably to 4.64 or more. In addition, the upper limit of the mass ratio SiO2 / (B2O3+Li2O) is preferably set to 9.5 or less, and more preferably to less than 8.6.

[0080] A high sum of the contents of SiO₂, Li₂O, Al₂O₃, and B₂O₃ [SiO₂ + Li₂O + Al₂O₃ + B₂O₃] facilitates chemical strengthening, resulting in high-strength glass. Therefore, the lower limit of [SiO₂ + Li₂O + Al₂O₃ + B₂O₃] is preferably set to 75.0% or higher, 77.0% or higher, 79.0% or higher, 80.0% or higher, 83.0% or higher, or 85.0% or higher. The upper limit is not particularly limited and can be, for example, less than 100% or 99% or lower.

[0081] P2O5 is an essential component that can be added to act as a crystal nucleating agent for glass. By setting the amount of P2O5 to 10.0% or less, deterioration of the devitrification of the glass and phase separation of the glass can be avoided.

[0082] The upper limit is preferably set to 8.0% or less, 6.0% or less, 5.0% or less, or 4.0% or less. The lower limit is greater than 0%, for example, 0.5% or more, 1.0% or more, or 1.5% or more.

[0083] The K2O component is an arbitrary component that is involved in chemical strengthening when its content is greater than 0%. The lower limit of the K2O component can be set to 0% or more, greater than 0%, 0.1% or more, 0.3% or more, or 0.5% or more.

[0084] Furthermore, by setting the K2O content to 5.0% or less, crystallization can be promoted. Therefore, the upper limit of the K2O content is preferably set to 5.0% or less, 4.0% or less, 3.5% or less, or 3.0% or less.

[0085] The Na2O component is an arbitrary component that participates in chemical strengthening when its content is greater than 0%. By setting the Na2O component to 4.0% or less, the desired crystalline phase can be easily obtained. The upper limit of the Na2O component can be set to preferably 4.0% or less, 3.5% or less, more preferably 3.0% or less, and even more preferably 2.5% or less. The lower limit of the Na2O component can be set to 0% or more.

[0086] MgO, CaO, SrO, BaO, and ZnO are arbitrary components that improve low-temperature melting properties when their contents exceed 0%, and may be contained within a range that does not impair the effects of the present invention.

[0087] Therefore, the upper limit of the MgO content is preferably 4.0%, 3.5%, 3.0%, or 2.5%. The lower limit of the MgO content is preferably 0%, more than 0%, 0.3%, or 0.4%.

[0088] The upper limit of the CaO content can be preferably set to 4.0% or less, 3.0% or less, 2.5% or less, or 2.0% or less. The lower limit of the CaO content can be set to 0% or more.

[0089] The upper limit of the SrO component can be preferably set to 4.0% or less, 3.0% or less, 2.5% or less, or 2.0% or less. The lower limit of the SrO component can be set to 0% or more.

[0090] The upper limit of the BaO component can be preferably set to 5.0% or less, 4.0% or less, 3.0% or less, 2.5% or less, or 2.0% or less. The lower limit of the BaO component can be set to 0% or more.

[0091] The upper limit of the ZnO content is preferably 10.0%, 9.0%, 8.5%, 8.0%, or 7.5%. The lower limit of the ZnO content is preferably 0%, more than 0%, 0.5%, or 1.0%.

[0092] The crystallized glass may or may not contain Nb2O5, Ta2O5 and TiO2 components within a range that does not impair the effects of the present invention.

[0093] The Nb2O5 component is an arbitrary component that improves the mechanical strength of the crystallized glass when its content is greater than 0%. The upper limit of the Nb2O5 component can be set to 5.0% or less, 4.0% or less, 3.5% or less, or 3.0% or less. The lower limit of the Nb2O5 component can be set to 0% or more.

[0094] The Ta2O5 component is an arbitrary component that improves the mechanical strength of the crystallized glass when its content is greater than 0%. The upper limit of the Ta2O5 component can be preferably set to 6.0% or less, 5.5% or less, 5.0% or less, or 4.0% or less. The lower limit of the Ta2O5 component can be set to 0% or more.

[0095] The TiO2 component is an arbitrary component that improves the chemical durability of crystallized glass when its content is greater than 0%. Preferably, the upper limit can be set to less than 1.0%, less than 0.8%, less than 0.5%, or less than 0.1%. The lower limit of the TiO2 component can be set to greater than 0%.

[0096] Furthermore, within the scope that does not impair the efficacy of the present invention, the crystallized glass may or may not contain La2O3, Gd2O3, Y2O3, WO3, TeO2, and Bi2O3. The blending amounts may be set to 0% to 2.0%, 0% to less than 2.0%, or 0% to 1.0%.

[0097] Furthermore, within the scope of not impairing the characteristics of the crystallized glass of the present invention, the crystallized glass may include or not include other components not mentioned above, such as metal components such as Yb, Lu, V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo (including their metal oxides).

[0098] Sb2O3 may also be included as a glass clarifier. On the other hand, by setting the Sb2O3 content to 3.0% or less, it is possible to suppress deterioration in transmittance in the short-wavelength region of the visible light range. Therefore, the upper limit is preferably set to 3.0% or less, more preferably 2.0% or less, even more preferably 1.0% or less, and even more preferably 0.6% or less. The lower limit of the Sb2O3 content can be set to 0% or more.

[0099] Furthermore, as a glass clarifier, in addition to the Sb2O3 component, one or more selected from the group consisting of SnO2, CeO2, As2O3, F, NOx, and SOx may be included, or not included. However, the upper limit of the clarifier content is preferably 2.0% or less, more preferably 1.0% or less, and most preferably 0.6% or less.

[0100] On the other hand, since the use of each of Pb, Th, Tl, Os, Be, Cl, and Se has tended to be avoided in recent years as harmful chemical substances, it is preferable that these components are not substantially contained.

[0101] The compressive stress CS (MPa) of the compressive stress layer of the inorganic composition product is preferably 550 MPa or greater, more preferably 600 MPa or greater, and even more preferably 700 MPa or greater. The upper limit is, for example, 1400 MPa or less, 1300 MPa or less, 1200 MPa or less, or 1100 MPa or less. Having such a compressive stress value can suppress the development of cracks and improve mechanical strength.

[0102] The compressive stress CS (MPa) can be measured by the method described in the Examples.

[0103] The central tensile stress CT (MPa) becomes an indicator of the degree of strengthening of the glass using chemical strengthening. If the CT value is high, the fragments when the glass breaks are small, and there is a tendency to break into small fragments. Therefore, for the impact resistance of the glass, the lower limit of the central tensile stress CT (MPa) is 70MPa or more, preferably 75MPa or more, more preferably 80MPa or more, and further preferably 85MPa or more. The upper limit is 200MPa or less, preferably 150MPa or less, and more preferably 120MPa or less. By having such a central tensile stress, it is possible to obtain the desired strengthened crystallized glass using chemical strengthening.

[0104] The central tensile stress CT (MPa) can be measured by the method described in the Examples.

[0105] The thickness DOLzero (μm) of the compressive stress layer also depends on the thickness of the inorganic composition product, but can be set to 8.0μm to 500μm. It can be preferably set to 9.5μm to 440μm, more preferably to 20μm to 400μm, more preferably to 30μm to 350μm, further preferably to 50μm to 300μm, and further preferably to 60μm to 120μm. For example, when the thickness of the inorganic composition product is 0.1mm, DOLzero can be set to 8.0μm to 25μm. The upper limit of DOLzero when the thickness of the inorganic composition product is 0.1mm can be set to, for example, 25μm or less, 22μm or less, or 20μm or less. In addition, the lower limit of DOLzero when the thickness of the inorganic composition product is 0.1mm can be set to, for example, 8.0μm or more, 8.5μm or more, or 9.5μm or more. For inorganic composition products with a thickness of 2.0 mm, the DOLzero value can be set to 160 μm to 500 μm. For inorganic composition products with a thickness of 2.0 mm, the upper limit of the DOLzero value can be set to, for example, 500 μm or less, 440 μm or less, or 400 μm or less. Furthermore, for inorganic composition products with a thickness of 2.0 mm, the lower limit of the DOLzero value can be set to, for example, 160 μm or more, or 180 μm or more.

[0106] The lower limit of the thickness of the compressive stress layer, DOLzero, is 8.0% or greater, preferably 9.0% or greater, more preferably 9.5% or greater, even more preferably 10% or greater, and further preferably 15% or greater, relative to the thickness of the inorganic composition product. The upper limit of the thickness of the compressive stress layer, DOLzero, is 25.0% or less, preferably 22.0% or less, and more preferably 20.0% or less, relative to the thickness of the inorganic composition product.

[0107] The thickness DOLzero (μm) of the compressive stress layer can be measured by the method described in the Examples.

[0108] When the crystallized glass related to the inorganic composition product is used as the substrate, the lower limit of the thickness (plate thickness) of the substrate is preferably 0.1 mm or more, more preferably 0.3 mm or more, even more preferably 0.4 mm or more, and further preferably 0.5 mm or more, and the upper limit of the thickness of the substrate is preferably 2.0 mm or less, more preferably 1.5 mm or less, even more preferably 1.1 mm or less, further preferably 1.0 mm or less, further preferably 0.9 mm or less, and further preferably 0.8 mm or less.

[0109] Here, the term "plate thickness of an inorganic composition product" refers to the distance between two substantially parallel, opposing principal surfaces of the inorganic composition product when the inorganic composition product is in the form of a plate having a finite thickness. For example, in the case of a short strip having a finite thickness, the term "plate thickness" refers to the distance between two substantially rectangular planes.

[0110] [Compressive stress CS (MPa)]×[thickness of the compressive stress layer DOLzero (μm)] / [thickness of the substrate t (mm)] is an indicator of impact resistance.

[0111] That is, the lower limit of [compressive stress CS (MPa)] × [thickness of compressive stress layer DOLzero (μm)] / [thickness of substrate t (mm)] of the tempered crystallized glass of the present invention is preferably 100 or more, more preferably 110 or more, and even more preferably 120 or more.

[0112] On the other hand, the upper limit of [compressive stress CS (MPa)] × [thickness of compressive stress layer DOLzero (μm)] / [thickness of substrate t (mm)] is preferably 350 or less, more preferably 300 or less, and even more preferably 250 or less. By setting it within such a numerical range, high-strength crystallized glass can be obtained by chemical strengthening.

[0113] The four-point bending strength (flexural stress) of the inorganic composition product is 760 MPa or higher, and can also be 800 MPa or higher, 850 MPa or higher, 900 MPa or higher, 950 MPa or higher, 1000 MPa or higher, 1050 MPa or higher, 1100 MPa or higher, 1150 MPa or higher, or 1200 MPa or higher. By having such a four-point bending strength, the inorganic composition product of one embodiment of the present invention has high resistance to deformation and is not easily broken.

[0114] The four-point bending strength was measured by the method described in the Examples.

[0115] The crystallized glass of the inorganic composition product according to the embodiment of the present invention (hereinafter referred to as "crystallized glass") can be produced by the following method. Specifically, the raw materials are uniformly mixed so that the respective components are within a predetermined content range, and then melted and formed to produce raw glass. Next, the raw glass is crystallized to produce crystallized glass.

[0116] The glass transition temperature Tg of the crystallized glass before crystallization is preferably 610° C. or lower, more preferably 600° C. or lower, and further preferably 590° C. or lower.

[0117] The heat treatment for crystallization may be performed at a single temperature step or at two temperature steps.

[0118] In the two-stage heat treatment, first, a nucleation step is performed by heat treatment at a first temperature, and after the nucleation step, a crystal growth step is performed by heat treatment at a second temperature higher than that in the nucleation step.

[0119] The first temperature of the two-stage heat treatment is preferably 450° C. to 750° C., more preferably 500° C. to 720° C., and even more preferably 550° C. to 680° C. The holding time at the first temperature is preferably 30 minutes to 2000 minutes, more preferably 180 minutes to 1440 minutes.

[0120] The second temperature of the two-stage heat treatment is preferably 550° C. to 850° C., more preferably 600° C. to 800° C. The holding time at the second temperature is preferably 30 to 600 minutes, more preferably 60 to 400 minutes.

[0121] In a one-stage heat treatment, the nucleation step and the crystal growth step are performed continuously at a single temperature. Typically, the temperature is raised to a predetermined heat treatment temperature, maintained at that temperature for a predetermined period of time, and then cooled.

[0122] When performing a single-stage heat treatment, the heat treatment temperature is preferably 600 to 800° C., more preferably 630 to 770° C. The holding time at the heat treatment temperature is preferably 30 to 500 minutes, more preferably 60 to 400 minutes.

[0123] Methods for forming a compressive stress layer in inorganic composition products include, for example, chemical strengthening, which involves exchanging an alkali component present in the surface layer of crystallized glass with an alkali component having a larger ion radius than the alkali component, thereby forming a compressive stress layer on the surface layer. Other methods include thermal strengthening, which involves heating the crystallized glass and then rapidly cooling it, and ion implantation, which involves injecting ions into the surface layer of the crystallized glass.

[0124] The inorganic composition product of the present invention can be produced, for example, by the following chemical strengthening method.

[0125] The crystallized glass is brought into contact with or immersed in a molten salt containing a salt of potassium, sodium, and lithium, such as a mixed salt of potassium nitrate (KNO3), sodium nitrate (NaNO3), and lithium nitrate (LiNO3), or a composite salt. The contact or immersion in the molten salt can be carried out in one stage or two stages.

[0126] In the case of a two-stage chemical strengthening treatment, for example, first, contact or immersion is performed in a mixed salt of potassium and sodium, a sodium salt, or a mixed salt of potassium, sodium, and lithium heated at 350°C to 550°C for 1 minute to 1440 minutes (preferably 15 minutes to 500 minutes, more preferably 30 minutes to 300 minutes). Then, second, contact or immersion is performed in a potassium salt, a mixed salt of potassium and sodium, a mixed salt of potassium and lithium, or a mixed salt of potassium, sodium, and lithium heated at 350°C to 550°C for 1 minute to 1440 minutes (preferably 60 minutes to 600 minutes). In the case of a two-stage chemical strengthening treatment, for example, the first-stage treatment is performed in a single bath or mixed bath of potassium (KNO3), sodium (NaNO3), or lithium (LiNO3), and the second-stage treatment is performed in a molten salt containing a salt of potassium, sodium, and lithium (for example, a mixed salt or a composite salt of potassium nitrate (KNO3), sodium nitrate (NaNO3), and lithium nitrate (LiNO3)).

[0127] In the case of a one-stage chemical strengthening treatment, for example, contact or immersion in a mixed salt containing potassium and sodium, a mixed salt containing potassium, sodium, and lithium, a mixed salt containing sodium, a mixed salt containing sodium and lithium (a mixed salt containing potassium and / or sodium and / or lithium) heated at 350°C to 550°C is performed for 1 minute to 1440 minutes (preferably 30 minutes to 500 minutes).

[0128] Example

[0129] Examples 1 to 27 and Comparative Example 1

[0130] 1. Production of inorganic composition products

[0131] As raw materials for the various components of crystallized glass, corresponding oxides, hydroxides, carbonates, nitrates, fluorides, chlorides, metaphosphate compounds and the like are selected, and these raw materials are weighed and uniformly mixed so as to have the compositions described in Tables 1 to 4.

[0132] Next, the mixed raw materials were placed in a platinum crucible and melted in an electric furnace at 1300°C to 1600°C for 2 to 24 hours. The molten glass was then stirred and homogenized, and the temperature was lowered to 1000°C to 1450°C, cast into a mold, and slowly cooled to produce raw glass. The resulting raw glass was heated under the crystallization conditions of the nucleation step and crystal growth step described in Tables 1 to 4 to produce crystallized glass.

[0133] The crystalline phase of the crystallized glass is determined by the angle of the peak that appears in the X-ray diffraction pattern using an X-ray diffraction analysis device (manufactured by Bruker, "D8Discover"). When confirming the X-ray diffraction patterns of the crystallized glasses of Examples 1 to 27, a peak is confirmed at a position corresponding to the peak pattern of α-cristobalite and / or α-cristobalite solid solution, thereby determining that α-cristobalite and / or α-cristobalite solid solution is precipitated as the main crystalline phase. In addition, when observing the X-ray diffraction pattern of the crystallized glass of Comparative Example 1, a peak of α-cristobalite is not confirmed, and a peak is confirmed at a position corresponding to the peak pattern of Li2Si2O5 and α-quartz, thereby determining that Li2Si2O5 and α-quartz are the main crystalline phases.

[0134] The glass transition point (Tg) of the glasses of Examples 1 to 27 and Comparative Example 1 before crystallization was measured in accordance with the Japan Optical Glass Industries Association standard JOGIS08-2019 “Measurement method of thermal expansion of optical glass”.

[0135] In Example 16 and Comparative Example 1, no measurement was possible.

[0136] The crystallized glasses produced in Example 1 and Comparative Example 1 were cut and ground, and then subjected to parallel polishing of the surfaces thereof to obtain crystallized glass substrates so as to have the thicknesses shown in Tables 5 to 9.

[0137] The crystallized glass substrate was used as a base material to obtain chemically strengthened crystallized glass substrates of Examples 1-1 to 1-29 and Comparative Example 1-1.

[0138] Examples 1-1 to 1-29 used the crystallized glass of Example 1 and were chemically strengthened under the strengthening conditions shown in Tables 5 to 9. The crystallized glass was ground to a width of 72 mm × a length of 135 mm and a thickness as shown in Tables 5 to 9.

[0139] Comparative Example 1-1 used the crystallized glass of Comparative Example 1 and performed a chemical strengthening treatment under the strengthening conditions shown in Table 9.

[0140] For example, "KNO3 10:NaNO3 1, 450°C x 120 min" in Example 1-1 (first stage of strengthening conditions) in Table 5 means immersion for 120 minutes in a mixed bath at 450°C in which potassium salt and sodium salt are mixed at a mass ratio of potassium salt:sodium salt = 10:1.

[0141] For example, "KNO 3 , 400° C.×300 min" in Example 1-2 (second stage of chemical strengthening) in Table 5 means immersion in a potassium salt bath at 400° C. for 300 minutes.

[0142] [Table 1]

[0143]

[0144] [Table 2]

[0145]

[0146] [Table 3]

[0147]

[0148] [Table 4]

[0149]

[0150] 2. Evaluation of inorganic composition products

[0151] The following properties of the obtained tempered crystallized glass substrate were measured and a four-point bending strength test was performed. The results are shown in Tables 5 to 9.

[0152] The photoelastic constant (β) is calculated by applying a compressive load in a predetermined direction to a sample, which is polished to form a circular plate with a diameter of 25 mm and a thickness of 8 mm. The optical path difference generated at the center of the glass is measured and calculated using the equation δ = β·d·F. In this equation, the optical path difference is expressed as δ (nm), the glass thickness is expressed as d (mm), and the apparent stress is expressed as F (MPa).

[0153] The compressive stress CS (MPa) of the compressive stress layer was measured using a glass surface stress meter (FSM-6000LE series, manufactured by Orihara Seisakusho). The measurement light source used a 365nm wavelength. The refractive index at a wavelength of 365nm was calculated using a quadratic approximation based on the V-block method specified in JIS B 7071-2:2018, using the measured refractive index values ​​for C-rays, d-rays, F-rays, and g-rays.

[0154] The photoelastic constant used in the CS measurement was calculated using a quadratic approximation based on the measured values ​​of the photoelastic constant at wavelengths of 435.8 nm, 546.1 nm, and 643.9 nm. The photoelastic constant used was 31.3. The CS value for Comparative Example 1-1 was calculated using the value from Example 2 of Patent Document 2.

[0155] The depth DOLzero (μm) and central tensile stress (CT) of the compressive stress layer at a compressive stress of 0 MPa were measured using a scattered light photoelasticity stress meter (SLP-1000, manufactured by Orihara Seisakusho). A light source with a wavelength of 405 nm was used for Examples 1-1 to 1-9, and a light source with a wavelength of 518 nm was used for Examples 1-10 to 1-29.

[0156] The refractive index value for a wavelength of 405 nm or 518 nm is calculated using a quadratic approximation from the measured refractive index values ​​for the wavelengths of C-rays, d-rays, F-rays, and g-rays according to the V-block method specified in JIS B 7071-2:2018.

[0157] In addition, the "substrate thickness" shown in Tables 5 to 9 is the thickness of the chemically strengthened crystallized glass substrate (mm), and the "CS×DOLzero / substrate thickness" shown in Tables 5 to 9 is the value obtained by dividing DOLzero (μm) by the thickness of the chemically strengthened crystallized glass substrate (mm) and multiplying it by the compressive stress CS (MPa).

[0158] The photoelastic constants for wavelengths of 405 nm and 518 nm used in DOLzero and CT measurements can be calculated using a quadratic approximation based on the measured values ​​of the photoelastic constants for wavelengths of 435.8 nm, 546.1 nm, and 643.9 nm. A value of 31.0 was used for Examples 1-1 to 1-9, and a value of 30.1 was used for Examples 1-10 to 1-29. The CS value for Comparative Example 1-1 is the value from Example 2 of Patent Document 2.

[0159] (2) Four-point bending strength test

[0160] A four-point bending strength test was conducted on the crystallized glass substrate using a bending tester (manufactured by Tateno Machinery Co., Ltd., "TFM-01") in accordance with JIS 1601:2008, with the distance between the outer support points of the support being 40 mm, the distance between the inner support points being 20 mm, and the crosshead speed being 10 mm / min. The bending stress (MPa) was measured. The results are shown in Tables 5 to 9.

[0161] [Table 5]

[0162]

[0163] [Table 6]

[0164]

[0165] [Table 7]

[0166]

[0167] [Table 8]

[0168]

[0169] [Table 9]

[0170]

[0171] While several embodiments and / or examples of the present invention have been described in detail above, it is readily apparent to those skilled in the art that various modifications may be made to these illustrative embodiments and / or examples without materially departing from the novel teachings and effects of the present invention. Therefore, these various modifications are within the scope of the present invention.

[0172] The contents of the documents described in this specification and the applications on which the present application claims priority under the Paris Convention are based are incorporated herein by reference in their entirety.

Claims

1. An inorganic composition product made by strengthening crystallized glass; The crystallized glass contains one or more selected from α-cristobalite and α-cristobalite solid solution as the main crystalline phase; Calculated in mass % of oxide conversion: The content of SiO2 component is 50.0% to 75.0%; The content of Li2O component is 3.0% to 10.0%; The content of Al2O3 component is 5.0% or more and less than 15.0%; The content of B2O3 is greater than 0% and less than 10.0%; The content of P2O5 is greater than 0% and less than 10.0%; The mass ratio SiO2 / (B2O3+Li2O) is 3.0 to 10.0; The inorganic composition product has a compressive stress layer on the surface and has a four-point bending strength of 760 MPa or more.

2. The inorganic composition product according to claim 1, wherein: The crystallized glass is expressed in mass % as oxides: The content of ZrO2 is greater than 0% and less than 10.0%; The total content of Al2O3 and ZrO2 components is 10.0% or more.

3. The inorganic composition product according to claim 1 or 2, wherein: The crystallized glass is expressed in mass % as oxides: The content of K2O component is 0% to 5.0%.

4. The inorganic composition product according to claim 1 or 2, wherein: The crystallized glass is expressed in mass % as oxides: The content of Na2O component is 0% to 4.0%; The content of MgO component is 0% to 4.0%; The content of CaO component is 0% to 4.0%; The content of SrO component is 0% to 4.0%; The content of BaO component is 0% to 5.0%; The content of ZnO component is 0% to 10.0%; The content of Sb2O3 component is 0% to 3.0%.

5. The inorganic composition product according to claim 1 or 2, wherein: The crystallized glass is expressed in mass % as oxides: The content of Nb2O5 component is 0% to 5.0%; The content of Ta2O5 component is 0% to 6.0%; The content of the TiO2 component is from 0% to less than 1.0%.

6. The inorganic composition product according to claim 1 or 2, wherein: The crystallized glass has a glass transition temperature Tg of 610° C. or lower before crystallization.

7. The inorganic composition product according to claim 1 or 2, wherein: [Compressive stress CS (MPa)]×[Thickness of the compressive stress layer DOLzero (μm)] / [Thickness of the substrate t (mm)] is 100 to 350.

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