Inorganic composition product

Abstract

The present invention is an inorganic composition product obtained by strengthening a crystallized glass containing, as a main crystal phase, one or more elements selected from the group consisting of alpha-cristobalite and alpha-cristobalite solid solutions, and having, in terms of mass% in terms of oxides: 50.0-75.0% of an SiO2 component; the content of the Li2O component is 3.0% to 10.0%; the content of the Al2O3 component is 5.0% or more and less than 15.0%; the content of the B2O3 component is more than 0% to 10.0% or less; and the content of the P2O5 component is greater than 0% to 10.0% or less; the mass ratio of SiO2 / (B2O3 + Li2O) is from 3.0 to 10.0; the thickness (DOLzero) of the compressive stress layer on the surface of the inorganic composition product is 8.0% to 25.0% of the plate thickness of the inorganic composition product; and a central tensile stress (CT) of 70 MPa to 120 MPa.

Description

Technical Field

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

[0002] Various glasses are expected to be used as cover glasses or housings for protecting the displays of portable electronic devices such as smartphones and tablet PCs (Personal Computers), or as protectors, interior bezels or control panels, touch panel materials, smart keys, etc. for protecting the lenses of in-vehicle optical devices. Moreover, these devices need to be used in harsh environments, and the demand for glass with higher strength is gradually increasing.

[0003] Conventionally, chemically strengthened glass has been used as a material for protective component applications and the like. However, many accidents of breakage occur when portable devices such as smartphones are dropped, which has become a problem. In particular, crystallized glass that is not easily broken when dropped on a rough surface such as asphalt with unevenness is needed.

[0004] If the central tensile stress (CT (central tensile stress) [MPa]) is high, when the glass breaks, the glass fragments tend to be small and become smashed into pieces. Furthermore, when used for applications such as protective components, the glass surface is sometimes polished for use. However, since the CT decreases when the glass surface is polished, it is necessary to increase the CT of the glass before polishing in advance. However, since the CT is too high when there is no polishing step, when the glass breaks, there is a problem that the glass fragments become too small and become smashed. Also, the thickness of the compressive stress layer (DOL (Depth of layer) zero [μm]) affects the difficulty of glass breakage and the size of the glass fragments when the glass breaks. Thus, a glass that can also cope with the case without a polishing step, whose CT is not too high and has a certain thickness (DOL zero) of the compressive stress layer, has been sought.

[0005] Patent Document 1 discloses the material composition of a crystallized glass substrate for a chemically strengthenable information recording medium. It is stated that the α-cristobalite-based crystallized glass described in Patent Document 1 can be chemically strengthened and can be used as a high-strength material substrate. However, for crystallized glass for information recording media typified by a hard disk substrate, use in a harsh environment has not been envisioned.

[0006] Prior Art Documents

[0007] Patent Document

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2008-254984 Summary of the Invention

[0009] An object of the present invention is to provide an inorganic composition product of strengthened crystallized glass that is not easily broken when dropped onto a rough surface. Furthermore, an object of the present invention is to provide an inorganic composition product of strengthened crystallized glass having a center tensile stress (CT) that is not too high and having a certain thickness (DOLzero) of the compressive stress layer.

[0010] The present invention provides the following inorganic composition products.

[0011] (Composition 1)

[0012] An inorganic composition product obtained by strengthening crystallized glass, wherein the crystallized glass contains one or more selected from α-tridymite and α-tridymite solid solution as the main crystal phase, and in terms of mass% in terms of oxide conversion:

[0013] The content of the SiO2 component is 50.0% to 75.0%;

[0014] The content of the Li2O component is 3.0% to 10.0%;

[0015] The content of the Al2O3 component is 5.0% or more and less than 15.0%;

[0016] The content of the B2O3 component is more than 0% and 10.0% or less; and

[0017] The content of the P2O5 component is more than 0% and 10.0% or less;

[0018] The mass ratio of SiO2 / (B2O3 + Li2O) is 3.0 to 10.0;

[0019] The thickness (DOLzero) of the compressive stress layer on the surface of the inorganic composition product is 8.0% to 25.0% of the plate thickness of the inorganic composition product;

[0020] The center tensile stress (CT) is 70 MPa to 120 MPa.

[0021] (Composition 2)

[0022] An inorganic composition product obtained by strengthening crystallized glass, wherein the crystallized glass contains one or more selected from α-tridymite and α-tridymite solid solution as the main crystal phase;

[0023] In terms of mass% in terms of oxide conversion:

[0024] The content of the SiO2 component is 50.0% to 75.0%;

[0025] The content of the Li2O component is 3.0% to 10.0%;

[0026] The content of the Al2O3 component is 5.0% or more and less than 15.0%;

[0027] The content of the B2O3 component is more than 0% and 10.0% or less; and

[0028] The content of the P2O5 component is more than 0% and 10.0% or less;

[0029] The mass ratio of SiO2 / (B2O3 + Li2O) is 3.0 to 10.0;

[0030] The thickness (DOLzero) of the compressive stress layer on the surface of the inorganic composition product is 8.0 μm to 500 μm;

[0031] The central tensile stress (CT) is 70 MPa to 120 MPa.

[0032] (Composition 3)

[0033] The inorganic composition product according to Composition 1 or Composition 2, wherein

[0034] The crystallized glass is in terms of mass% in terms of oxide conversion:

[0035] The content of the ZrO2 component is more than 0% and 10.0% or less; and

[0036] The total content of the Al2O3 component and the ZrO2 component is 10.0% or more.

[0037] (Composition 4)

[0038] The inorganic composition product according to any one of Compositions 1 to 3, wherein

[0039] The crystallized glass is in terms of mass% in terms of oxide conversion:

[0040] The content of the K2O component is 0% to 5.0%.

[0041] (Composition 5)

[0042] The inorganic composition product according to any one of Compositions 1 to 4, wherein

[0043] The crystallized glass is in terms of mass% in terms of oxide conversion:

[0044] The content of the Na2O component is 0% to 4.0%;

[0045] The content of the MgO component is 0% to 4.0%;

[0046] The content of the CaO component is 0% to 4.0%;

[0047] The content of the SrO component is 0% to 4.0%;

[0048] The content of the BaO component is 0% to 5.0%;

[0049] The content of the ZnO component is 0% to 10.0%; and

[0050] The content of the Sb2O3 component is 0% to 3.0%.

[0051] (Composition 6)

[0052] For the inorganic composition product according to any one of Composition 1 to Composition 5, wherein

[0053] For the crystallized glass, in terms of mass% in terms of oxide conversion:

[0054] The content of the Nb2O5 component is 0% to 5.0%;

[0055] The content of the Ta2O5 component is 0% to 6.0%; and

[0056] The content of the TiO2 component is 0% or more and less than 1.0%.

[0057] (Composition 7)

[0058] For the inorganic composition product according to any one of Composition 1 to Composition 6, wherein

[0059] The glass transition temperature (Tg) of the glass before crystallization of the crystallized glass is 610 °C or lower.

[0060] (Composition 8)

[0061] For the inorganic composition product according to any one of Composition 1 to Composition 7, wherein

[0062] The plate thickness of the inorganic composition product is 0.1 mm to 2.0 mm.

[0063] According to the present invention, by controlling the amount of LiO2, adjusting the amounts of SiO2 and Al2O3, it is easy to manufacture an inorganic composition product related to strengthened crystallized glass that is not easily broken when dropped onto a rough surface, and it can be stably manufactured. Furthermore, according to the present invention, an inorganic composition product having a central tensile stress (CT) that is not too high and a certain thickness (DOLzero) of the compressive stress layer can be provided.

[0064] The "inorganic composition product" in the present invention is composed of inorganic composition materials such as glass, crystallized glass, ceramics, or composite materials of these materials. As the "product" of the present invention, for example, products that are shaped into the required shape by processing or chemical reactions of these inorganic materials are suitable. Furthermore, compressed powders obtained by crushing inorganic materials and then applying pressure, or sintered bodies obtained by sintering the compressed powders, etc. are also suitable. The shape of the product obtained here is not limited by smoothness, curvature, size, etc. For example, it can be a plate-shaped substrate, a molded body with curvature, or a three-dimensional structure with a complex shape, etc. Moreover, products obtained by chemically strengthening the inorganic composition materials are also suitable.

[0065] The inorganic composition product of the present invention makes flexible use of glass-based materials with high strength and processability and can be used in protective components of machines, etc. It can be used as the cover glass or housing of a smartphone, components of portable electronic devices such as a tablet PC or a wearable terminal, or components such as protective guards or substrates for head-up displays used in transportation bodies such as automobiles or airplanes. Furthermore, it can be used in other electronic devices, mechanical appliances, building components, components for solar panels, components for projectors, cover glass (windshields) for glasses or watches, etc. Detailed implementation modes

[0066] The following is a detailed description of the implementation modes and examples of the inorganic composition product of the present invention. However, the present invention is in no way limited to the following implementation modes and examples and can be implemented with appropriate modifications within the scope of the object of the present invention.

[0067] The inorganic composition product of the present invention and the crystallized glass that is its base material contain one or more selected from α-cristobalite and α-cristobalite solid solution as the main crystal phase. The crystallized glass in which these crystal phases are precipitated has high mechanical strength.

[0068] Here, the so-called "main crystal phase" in this specification corresponds to the crystal phase that contains the most in the crystallized glass determined by the peaks of the X-ray diffraction pattern.

[0069] In this specification, unless otherwise specifically denied, the content of each component is expressed as mass % in terms of oxides. Here, the so-called "in terms of oxides" means that when it is assumed that all the composition components of the crystallized glass are decomposed and changed into oxides, and the total mass of the oxides is set to 100 mass %, the amount of the oxides of each component contained in the crystallized glass is indicated in mass %. In this specification, A% to B% means A% or more and B% or less.

[0070] The inorganic composition product of the first embodiment of the present invention will be described below.

[0071] The devitrified glass of the inorganic composition product of the first embodiment of the present invention, and the devitrified glass that is its base material are based on mass % in terms of oxide conversion:

[0072] The content of the SiO2 component is 50.0% to 75.0%;

[0073] The content of the Li2O component is 3.0% to 10.0%;

[0074] The content of the Al2O3 component is 5.0% or more and less than 15.0%;

[0075] The content of the B2O3 component is more than 0% and 10.0% or less; and

[0076] The content of the P2O5 component is more than 0% and 10.0% or less;

[0077] The mass ratio SiO2 / (B2O3 + Li2O) is 3.0 to 10.0.

[0078] By having the above-mentioned main crystal phase and composition, the glass transition temperature of the devitrified glass becomes lower, the meltability of the raw materials is improved and it becomes easier to manufacture, and the obtained devitrified glass becomes easier to process such as 3D (three-dimensional) processing.

[0079] Hereinafter, the composition ranges of the respective components of the devitrified glass that constitutes the base material of the inorganic composition product of the present invention will be specifically described.

[0080] The SiO2 component is an essential component necessary to form one or more selected from α-cristobalite and α-cristobalite solid solution. If the content of the SiO2 component is 75.0% or less, an excessive increase in viscosity and deterioration of meltability can be suppressed. Furthermore, if it is 50.0% or more, deterioration of devitrification resistance can be suppressed.

[0081] Preferably, the upper limit is set to 74.0% or less, 73.0% or less, 72.0% or less, or 70.0% or less. And preferably, the lower limit is set to 55.0% or more, 58.0% or more, or 60.0% or more.

[0082] The Li2O component is a component that improves the meltability of the original glass. If its amount is 3.0% or more, an effect of improving the meltability of the original glass can be obtained. Furthermore, by setting it to 10.0% or less, an increase in the formation of lithium disilicate crystals can be suppressed. Furthermore, the Li2O component is a component related to chemical strengthening.

[0083] Preferably, the lower limit is set to 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, or 5.5% or more. Further preferably, the upper limit is set to 9.0% or less, 8.5% or less, or 8.0% or less.

[0084] The Al2O3 component is a suitable component for improving the mechanical strength of the crystallized glass. If the content of the Al2O3 component is less than 15.0%, deterioration of meltability and devitrification can be suppressed. Moreover, if it is 5.0% or more, a decrease in mechanical strength can be suppressed.

[0085] Preferably, the upper limit is set to 14.5% or less, 14.0% or less, 13.5% or less, or 13.0% or less. And the lower limit can be set to 5.5% or more, 5.8% or more, 6.0% or more, 6.5% or more, or 8.0% or more.

[0086] The B2O3 component is a suitable component for lowering the glass transition temperature of the crystallized glass. If its amount is 10.0% or less, a decrease in chemical durability can be suppressed.

[0087] Preferably, the upper limit is set to 8.0% or less, 7.0% or less, 5.0% or less, or 4.0% or less. And the lower limit is greater than 0%, preferably set to 0.001% or more, 0.01% or more, 0.05% or more, 0.10% or more, or 0.30% or more.

[0088] The ZrO2 component is a component that can improve mechanical strength. If its amount is 10.0% or less, deterioration of meltability can be suppressed.

[0089] Preferably, the upper limit is set to 10.0% or less, 9.0% or less, 8.5% or less, or 8.0% or less. And preferably, the lower limit can be set to greater than 0%, 1.0% or more, 1.5% or more, or 2.0% or more.

[0090] If [Al2O3 + ZrO2], which is the sum of the contents of the Al2O3 component and the ZrO2 component, is large, the compressive stress on the surface becomes large when strengthening is performed. 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.

[0091] On the other hand, by setting it to 22.0% or less, deterioration of meltability 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.

[0092] The mass ratio of SiO2 / (B2O3+Li2O) is from 3.0 to 10.0. By setting this mass ratio to be from 3.0 to 10.0, it helps to lower the viscosity of the glass, making it easier to fabricate the glass, and increasing the amount of alkali ions that undergo ion exchange during chemical strengthening, enabling the production of the desired strengthened and crystallized glass with CS30 (compressive stress at a depth of 30 μm from the outermost surface).

[0093] Therefore, the lower limit of the mass ratio of SiO2 / (B2O3+Li2O) is preferably set to 3.5 or more, more preferably 4.64 or more. Also, the upper limit of the mass ratio of SiO2 / (B2O3+Li2O) is preferably set to 9.5 or less, more preferably less than 8.6.

[0094] If [SiO2+Li2O+Al2O3+B2O3], which is the sum of the contents of the SiO2 component, Li2O component, Al2O3 component, and B2O3 component, is large, chemical strengthening is facilitated and glass with high strength can be obtained. Therefore, the lower limit of [SiO2+Li2O+Al2O3+B2O3] is preferably set to 75.0% or more, 77.0% or more, 79.0% or more, 80.0% or more, 83.0% or more, or 85.0% or more. The upper limit is not particularly limited and can be set to less than 100%, or 99% or less, for example.

[0095] The P2O5 component is an essential component that can be added to act as a glass crystallization nucleating agent. By setting the amount of the P2O5 component to 10.0% or less, deterioration of the devitrification resistance of the glass or phase separation of the glass can be suppressed.

[0096] The upper limit is preferably set to 8.0% or less, 6.0% or less, 5.0% or less, or 4.0% or less. And the lower limit is greater than 0%, and can be set to 0.5% or more, 1.0% or more, or 1.5% or more, for example.

[0097] The K2O component is an optional component related to 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.

[0098] Furthermore, by setting the K2O component to 5.0% or less, precipitation of crystals can be promoted. Therefore, the upper limit of the K2O component is preferably set to 5.0% or less, 4.0% or less, 3.5% or less, or 3.0% or less.

[0099] The Na2O component is any component related to 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 is preferably settable to 4.0% or less, 3.5% or less, more preferably 3.0% or less, and still more preferably 2.5% or less. The lower limit of the Na2O component can be set to 0% or more.

[0100] The MgO component, CaO component, SrO component, BaO component, and ZnO component are any components that improve the low-temperature fusibility when their respective contents are greater than 0%, and can be contained within the range that does not impair the effects of the present invention.

[0101] Therefore, the upper limit of the MgO component is preferably settable to 4.0% or less, 3.5% or less, 3.0% or less, or 2.5% or less. And the lower limit of the MgO component is preferably settable to 0% or more, greater than 0%, 0.3% or more, 0.4% or more.

[0102] The upper limit of the CaO component is preferably settable to 4.0% or less, 3.0% or less, 2.5% or less, or 2.0% or less. The lower limit of the CaO component can be set to 0% or more.

[0103] The upper limit of the SrO component is preferably settable 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.

[0104] The upper limit of the BaO component is preferably settable 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.

[0105] The upper limit of the ZnO component is preferably settable to 10.0% or less, 9.0% or less, 8.5% or less, 8.0% or less, or 7.5% or less. And the lower limit of the ZnO component is preferably settable to 0% or more, greater than 0%, 0.5% or more, 1.0% or more.

[0106] The crystallized glass can contain the Nb2O5 component, Ta2O5 component, and TiO2 component respectively within the range that does not impair the effects of the present invention, or can also not contain them.

[0107] The Nb2O5 component is any component that improves the mechanical strength of the crystallized glass when its content is greater than 0%. The upper limit is preferably settable 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.

[0108] The Ta2O5 component is an optional component that improves the mechanical strength of the crystallized glass when its content is greater than 0%. Preferably, the upper limit can be 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.

[0109] The TiO2 component is an optional component that improves the chemical durability of the crystallized glass when its content is greater than 0%. Preferably, the upper limit can be set to less than 1.0%, 0.8% or less, 0.5% or less, or 0.1% or less. The lower limit of the TiO2 component can be set to 0% or more.

[0110] Furthermore, within the range that does not impair the effects of the present invention, the crystallized glass may also contain La2O3 component, Gd2O3 component, Y2O3 component, WO3 component, TeO2 component, Bi2O3 component, or may not contain them. The blending amounts can be set to 0% to 2.0%, 0% to less than 2.0%, or 0% to 1.0% respectively.

[0111] Furthermore, in the crystallized glass, within the range that does not impair the characteristics of the crystallized glass of the present invention, other components not mentioned above may be included, or may not be included. For example, metal components such as Yb, Lu, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo (metal oxides containing these metal components), etc.

[0112] As a glass fining agent, the Sb2O3 component may be contained. On the other hand, by setting the Sb2O3 component to 3.0% or less, the deterioration of the transmittance in the short wavelength region of the visible light region can be suppressed. Therefore, preferably, the upper limit can be set to 3.0% or less, more preferably 2.0% or less, still more preferably 1.0% or less, and further preferably 0.6% or less. The lower limit of the Sb2O3 component can be set to 0% or more.

[0113] Furthermore, as a glass fining agent, in addition to the Sb2O3 component, one or more selected from the group consisting of SnO2 component, CeO2 component, As2O3 component, and F, NOx, SOx may be included, or may not be included. However, the content of the fining agent is preferably set to 2.0% or less, more preferably 1.0% or less, and most preferably 0.6% or less.

[0114] On the other hand, each component of Pb, Th, Tl, Os, Be, Cl, and Se has a tendency to be avoided in recent years as harmful chemical substances, so it is preferably substantially free of these components.

[0115] The compressive stress (CS [MPa]) of the compressive stress layer of the inorganic composition product is preferably 550 MPa or more, more preferably 600 MPa or more, and still more preferably 700 MPa or more. The upper limit is, for example, 1400 MPa or less, 1300 MPa or less, 1200 MPa or less, or 1100 MPa or less. By having such a compressive stress value, the progress of cracks can be suppressed and the mechanical strength can be improved.

[0116] The center tensile stress (CT [MPa]) is an index of the degree of strengthening of the glass for chemical strengthening. If the value of CT is high, the fragments at the time of glass breakage are small and tend to become pulverized. Therefore, for the impact resistance of the glass, the center tensile stress (CT [MPa]) is 70 MPa or more, preferably 75 MPa or more, more preferably 80 MPa or more, and still preferably 85 MPa or more. The upper limit is 120 MPa or less, preferably 115 MPa or less, or 110 MPa or less. By having such a center tensile stress, the desired strengthened crystallized glass brought about by chemical strengthening can be obtained.

[0117] The thickness (DOLzero [μm]) of the compressive stress layer on the surface also depends on the thickness of the inorganic composition product, but can be set to 8.0 μm to 500 μm. More preferably, it can be set to 9.5 μm to 440 μm, still more preferably 20 μm to 400 μm, further preferably 30 μm to 350 μm, still further preferably 50 μm to 300 μm, and even more preferably 60 μm to 120 μm. In the following description, the "thickness of the compressive stress layer on the surface" is sometimes simply referred to as the "thickness of the compressive stress layer". For example, when the plate thickness of the inorganic composition product is 0.1 mm, DOLzero can be set to 8.0 μm to 25 μm. When the plate thickness of the inorganic composition product is 0.1 mm, the upper limit of DOLzero can be, for example, 25 μm or less, 22 μm or less, 20 μm or less. And when the plate thickness of the inorganic composition product is 0.1 mm, the lower limit of DOLzero can be, for example, 8.0 μm or more, 8.5 μm or more, 9.5 μm or more. When the plate thickness of the inorganic composition product is 2.0 mm, DOLzero can be set to 160 μm to 500 μm. When the plate thickness of the inorganic composition product is 2.0 mm, the upper limit of DOLzero can be, for example, 440 μm or less, 420 μm or less, or 400 μm or less.

[0118] Furthermore, when the plate thickness of the inorganic composition product is 2.0 mm, the lower limit of DOLzero can be, for example, 120 μm or more, 160 μm or more, 180 μm or more.

[0119] Furthermore, the lower limit of the thickness of the compressive stress layer (DOLzero) relative to the plate thickness of the inorganic composition product may be 8.0% or more, preferably 9.0% or more, more preferably 9.5% or more, still more preferably 10% or more, and further preferably 15% or more. Furthermore, the upper limit of the thickness of the compressive stress layer (DOLzero) relative to the plate thickness of the inorganic composition product may be 25.0% or less, preferably set to 22.0% or less, and more preferably 20.0% or less.

[0120] When the crystallized glass of the inorganic composition product is used as a 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, still more preferably 0.4 mm or more, and further preferably 0.5 mm or more. The upper limit is preferably 2.0 mm or less, more preferably 1.5 mm or less, still more preferably 1.1 mm or less, further preferably 1.0 mm or less, still further preferably 0.9 mm or less, and even more preferably 0.8 mm or less.

[0121] Here, the "plate thickness of the inorganic composition product" is the distance between two main surfaces that are arranged slightly parallel and opposite to each other when the shape of the inorganic composition product becomes a plate shape with a finite thickness. For example, as long as it is a strip shape with a finite thickness, it refers to the distance between two substantially rectangular planes.

[0122] The inorganic composition product of the second embodiment of the present invention will be described below.

[0123] The inorganic composition product of the second embodiment of the present invention has a thickness of the compressive stress layer on the surface (DOLzero [μm]) of 8.0 μm to 500 μm.

[0124] The thickness of the compressive stress layer on the surface of the inorganic composition product of the second embodiment (DOLzero [μm]) is preferably 9.5 μm to 440 μm, more preferably 20 μm to 400 μm, still more preferably 30 μm to 350 μm, yet more preferably 50 μm to 300 μm, and further preferably 60 μm to 120 μm.

[0125] Furthermore, for the inorganic composition product of the second embodiment of the present invention, the lower limit of the thickness of the compressive stress layer (DOLzero) relative to the plate thickness of the inorganic composition product is preferably set to 8.0% or more, more preferably set to 9.0% or more, still more preferably set to 9.5% or more, yet more preferably set to 10% or more, and further preferably set to 15% or more. And the upper limit of the thickness of the compressive stress layer (DOLzero) relative to the plate thickness of the inorganic composition product is preferably set to 25.0% or less, more preferably set to 22.0% or less, and yet more preferably set to 20.0% or less.

[0126] The inorganic composition product of the second embodiment of the present invention has the same characteristics as the inorganic composition product of the first embodiment of the present invention, except for the above points. Furthermore, the necessary composition range and the suitable composition range of the strengthened crystallized glass of the inorganic composition product of the second embodiment of the present invention, and the crystallized glass serving as its base material, are the same as the necessary composition range and the suitable composition range of the strengthened crystallized glass of the inorganic composition product of the first embodiment of the present invention, and the crystallized glass serving as its base material.

[0127] The crystallized glass (hereinafter simply referred to as "crystallized glass") of the inorganic composition product of the first embodiment of the present invention and the inorganic composition product of the second embodiment of the present invention (hereinafter sometimes simply referred to as "the inorganic composition product of the present invention") can be produced by the following method. That is, the raw materials are uniformly mixed so that each component is within a specified content range, and then melted and formed to produce the raw glass. Then, this raw glass is crystallized to produce the crystallized glass.

[0128] The glass transition temperature (Tg) of the glass before crystallization of the crystallized glass is preferably 610 °C or lower, more preferably 600 °C or lower, and still more preferably 590 °C or lower.

[0129] The heat treatment for precipitating crystals can be carried out in one stage or in two-stage temperatures.

[0130] In the two-stage heat treatment, first, the nucleation step is carried out by heat treatment at the first temperature. After this nucleation step, the crystal growth step is carried out by heat treatment at the second temperature higher than the nucleation step.

[0131] The first temperature of the two-stage heat treatment can preferably be set to 450 °C to 750 °C, more preferably to 500 °C to 720 °C, and still more preferably to 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.

[0132] The second temperature of the two-stage heat treatment can preferably be set to 550 °C to 850 °C, more preferably to 600 °C to 800 °C. The holding time at the second temperature is preferably 30 minutes to 600 minutes, more preferably 60 minutes to 400 minutes.

[0133] In the one-stage heat treatment, the nucleation step and the crystal growth step are continuously carried out at one-stage temperature. Usually, the temperature is raised until the specified heat treatment temperature, and after reaching this heat treatment temperature, the temperature is maintained for a certain time, and then the temperature is lowered.

[0134] When performing the first-stage heat treatment, the heat treatment temperature is preferably 600°C to 800°C, more preferably 630°C to 770°C. Furthermore, the holding time at the heat treatment temperature is preferably 30 minutes to 500 minutes, more preferably 60 minutes to 400 minutes.

[0135] As a method for forming a compressive stress layer in an inorganic composition product, for example, there is a chemical strengthening method in which an alkaline component present in the surface layer of the crystallized glass is exchanged with an alkaline component having a larger ionic radius than the alkaline component to form a compressive stress layer in the surface layer. Furthermore, there are a thermal strengthening method in which the crystallized glass is heated and then rapidly cooled, and an ion implantation method in which ions are implanted into the surface layer of the crystallized glass.

[0136] The inorganic composition product of the present invention can be manufactured by, for example, the following chemical strengthening method.

[0137] The crystallized glass is brought into contact with or immersed in a molten salt containing salts of potassium, sodium, and lithium (for example, a mixed salt or a complex salt of potassium nitrate (KNO3), sodium nitrate (NaNO3), and lithium nitrate (LiNO3)). The treatment of bringing into contact with or immersing in this molten salt can be carried out in one stage or in two stages.

[0138] In the case of two-stage treatment, for example, in the first stage, it is brought into contact with or immersed in a mixed salt of potassium and sodium, or a sodium salt, or a mixed salt of potassium, sodium, and lithium heated to 350°C to 550°C for 1 minute to 1440 minutes, preferably 15 minutes to 500 minutes, more preferably 30 minutes to 300 minutes. Subsequently, in the second stage, it is brought into contact with or immersed 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 to 350°C to 550°C for 1 minute to 1440 minutes, preferably 60 minutes to 600 minutes.

[0139] In the case of two-stage treatment, for example, preferably, the treatment in the first stage is a single bath, a mixed bath of potassium (KNO3) or sodium (NaNO3) or lithium (LiNO3), and the treatment in the second stage is a molten salt containing salts of potassium, sodium, and lithium, for example, a mixed salt or a complex salt of potassium nitrate (KNO3), sodium nitrate (NaNO3), and lithium nitrate (LiNO3).

[0140] In the case of one-stage chemical strengthening treatment, for example, it is brought into contact with or immersed in a mixed salt of potassium and sodium, or a mixed salt of potassium, sodium, and lithium, a sodium salt-containing salt, a sodium and lithium-containing salt (a mixed salt containing potassium and / or sodium and / or lithium) heated to 350°C to 550°C for 1 minute to 1440 minutes, preferably 30 minutes to 500 minutes.

[0141] Examples

[0142] Example 1, Comparative Example 1, and Comparative Example 2

[0143] 1. Production of inorganic composition products

[0144] As raw materials for the respective components of the crystallized glass, raw materials corresponding to oxides, hydroxides, carbonates, nitrates, fluorides, chlorides, metaphosphate compounds, etc. of each component were selected, and these raw materials were weighed and uniformly mixed so as to have the composition described in Table 1.

[0145] Next, the mixed raw materials were put into a platinum crucible and melted in an electric furnace at 1300°C to 1600°C for 2 hours to 24 hours. After that, the melted glass was stirred and homogenized, then the temperature was lowered to 1000°C to 1450°C and cast into a mold, and slowly cooled to produce the original glass. The obtained original glass was heated under the crystallization conditions of the nucleation step and the crystal growth step described in Table 1 to produce the crystallized glass.

[0146] The crystal phase of the crystallized glass was determined by the angles of the peaks shown in the X-ray diffraction pattern obtained using an X-ray diffraction analyzer (manufactured by Bruker Corporation, "D8 Discover"). When the X-ray diffraction pattern of the crystallized glass of Example 1 was confirmed, since peaks were confirmed at positions corresponding to the peak patterns of α-cristobalite and / or α-cristobalite solid solution, it was determined that α-cristobalite and / or α-cristobalite solid solution precipitated as the main crystal phase. Furthermore, when the X-ray diffraction pattern of the crystallized glass of Comparative Example 1 was confirmed, since the peak of α-cristobalite was not confirmed, and peaks were confirmed at positions corresponding to the peak patterns of Li2Si2O5 and α-quartz, it was judged that Li2Si2O5 and α-quartz were the main crystal phases. In Comparative Example 2, since the peaks of α-cristobalite and α-cristobalite solid solution were not confirmed by the X-ray diffraction analyzer (manufactured by Bruker Corporation, "D8 Discover"), after confirmation by the lattice image brought by the electron diffraction image, the crystal phase was confirmed by the analysis using EDX (energy dispersive X-ray spectrometer). As a result, it was confirmed that the crystal phase of the glass of Comparative Example 2 was MgAl2O4 and MgTi2O4.

[0147] In accordance with the Japan Optical Glass Industry Association standard JOGIS08-2019 "Method for Measuring the Thermal Expansion of Optical Glasses", the glass transition point (Tg) of the glass before crystallization of Example 1 was measured.

[0148] The crystallized glass produced in Example 1, Comparative Example 1, and Comparative Example 2 was cut and ground, and then face-to-face parallel grinding was performed to obtain a plate thickness (thickness) as shown in Tables 2 to 6, thereby obtaining a crystallized glass substrate.

[0149] Using this crystallized glass substrate as a base material, a chemically strengthened crystallized glass substrate was obtained.

[0150] In Examples 1-1 to 1-19, the crystallized glass of Example 1 was used and two-stage strengthening (chemical strengthening treatment) was performed under the strengthening conditions shown in Tables 2 to 5.

[0151] In Comparative Example 1-1 and Comparative Example 2-1, the crystallized glasses of Comparative Example 1 and Comparative Example 2 were respectively used, and one-stage strengthening (chemical strengthening treatment) was performed under the strengthening conditions shown in Table 6.

[0152] For example, “Na single 380 °C × 100 min” in Example 1-1 (the first stage of chemical strengthening) in Table 2 means that it was immersed in a single bath of sodium salt at 380 °C for 100 minutes.

[0153] In addition, for example, “K:Na:Li = 70:1:0.05 400 °C × 300 min” in Example 1-2 (the second stage of chemical strengthening) in Table 2 means that it was immersed in a mixed bath at 400 °C for 300 minutes, where the potassium salt, sodium salt, and lithium salt were mixed at a ratio of potassium salt:sodium salt:lithium salt = 70:1:0.05 by mass.

[0154]

Table 1

[0155]

[0156] 2. Evaluation of inorganic composition products

[0157] For the obtained strengthened crystallized glass substrates, the following characteristics were measured, and a sandpaper ball-drop test was performed. The results are shown in Tables 2 to 6.

[0158] (1) Measurement of DOLzero and CT

[0159] The photoelastic constant (β) was obtained by performing face-to-face grinding on the sample shape to form a disk shape with a diameter of 25 mm and a thickness of 8 mm, applying a compressive load in a specified direction, measuring the optical path difference generated at the center of the glass, and using the relational expression δ = β·d·F. In this relational expression, the optical path difference is denoted as δ (nm), the thickness of the glass is denoted as d (mm), and the stress is denoted as F (MPa).

[0160] The depth DOLzero (μm) at which the compressive stress of the compressive stress layer is 0 MPa and the central tensile stress (CT) are measured using a scattered light photoelastic stress meter (manufactured by Oriehara Seisakusho, "SLP-1000"). The light source used for the measurement was a light source with a wavelength of 518 nm.

[0161] The refractive index value at a wavelength of 518 nm is calculated using a quadratic approximation formula from the measured values of the refractive indices at the wavelengths of C line, d line, F line, and g line according to the V-block method specified in JIS B 7071-2:2018.

[0162] In addition, the "thickness" shown in Tables 2 to 6 is the thickness (μm) of the chemically strengthened crystallized glass substrate, and the "DOLzero / thickness" shown in Tables 2 to 6 is the value obtained by dividing DOLzero (μm) by the thickness (μm) of the chemically strengthened crystallized glass substrate.

[0163] The photoelastic constant at a wavelength of 518 nm used for the measurement of DOLzero and CT can be calculated using a quadratic approximation formula from the measured values of the photoelastic constants at wavelengths of 435.8 nm, 546.1 nm, and 643.9 nm. In Examples 1-1 to 1-19, 30.1 was used. In Comparative Example 1-1, 28.8 was used. In Comparative Example 2-1, 28.9 was used.

[0164] (2) Sandpaper ball-drop test

[0165] For the crystallized glass substrate, the sandpaper ball-drop test was carried out using the following method.

[0166] Sandpaper with a roughness of #180 was laid on a stainless steel base, and a crystallized glass substrate with a length of 150 mm and a width of 73 mm was placed thereon. Then, an iron ball with a diameter of φ6 mm and a mass of 0.87 g was dropped from a height of 10 cm above the center of the crystallized glass substrate to collide with the crystallized glass substrate. As long as the crystallized glass substrate was not broken, the height of the iron ball drop was increased by 10 cm, and the same test was continued until the crystallized glass substrate was broken. After breakage, the state of the fragments was observed. The height at which the crystallized glass substrate was broken and cracked is shown in Tables 2 to 6.

[0167] Ten large fragments were selected from the fragments of the broken crystallized glass substrate, and the weight of each fragment was measured. The volume of each fragment was calculated from the specific gravity of the substrate of 2.48, and the surface area of each fragment was obtained by dividing by the plate thickness. Using this surface area, the state (fracture mode) of the fragments was evaluated according to the following criteria. The results are shown in Tables 2 to 6.

[0168] 〇: 1 cm 2Four or more of the above fragments, or 10 cm 2 One or more of the above fragments

[0169] △: 1 cm 2 One to three of the above fragments

[0170] ×: 1 cm 2 Zero of the above fragments (all are small fragments less than 1 cm 2 of fine fragments)

[0171] As can be seen from Tables 2 to 6, the substrate of the present invention is hard and difficult to break, and even if it is broken, it is difficult to become pulverized.

[0172]

Table 2

[0173]

[0174]

Table 3

[0175]

[0176]

Table 4

[0177]

[0178]

Table 5

[0179]

[0180]

Table 6

[0181]

[0182] Although several embodiments and / or examples of the present invention have been described in detail above, those skilled in the art can easily make many changes to these illustrated embodiments and / or examples without substantially departing from the novel inspiration and effects of the present invention. Therefore, these many changes are included in the scope of the present invention.

[0183] All the documents described in this specification and the contents of the application that form the basis of the priority of the Paris Convention for this case are incorporated by reference.

Claims

1. An inorganic composition product is obtained by strengthening crystallized glass. The crystallized glass contains one or more selected from α-cristobalite and α-cristobalite solid solution as the main crystal phase, and in terms of mass% in terms of oxide conversion: 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% or more and less than 15.0%; The content of the B2O3 component is more than 0% and 10.0% or less; and The content of the P2O5 component is more than 0% and 10.0% or less; And the mass ratio SiO2 / (B2O3 + Li2O) is 3.0 to 10.0; The thickness (DOLzero) of the compressive stress layer on the surface of the inorganic composition product is 8.0% to 25.0% of the plate thickness of the inorganic composition product; The central tensile stress (CT) is 70 MPa to 120 MPa.

2. An inorganic composition product is obtained by strengthening crystallized glass. The crystallized glass contains one or more selected from α-cristobalite and α-cristobalite solid solution as the main crystal phase, and in terms of mass% in terms of oxide conversion: 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% or more and less than 15.0%; The content of the B2O3 component is more than 0% and 10.0% or less; and The content of the P2O5 component is more than 0% and 10.0% or less; And the mass ratio SiO2 / (B2O3 + Li2O) is 3.0 to 10.0; The thickness (DOLzero) of the compressive stress layer on the surface of the inorganic composition product is 8.0 μm to 500 μm; The central tensile stress (CT) is 70 MPa to 120 MPa.

3. The inorganic composition product according to claim 1 or claim 2, wherein, In terms of mass% in terms of oxide conversion of the crystallized glass: The content of the ZrO2 component is more than 0% and 10.0% or less; and The total content of the Al2O3 component and the ZrO2 component is 10.0% or more.

4. The inorganic composition product according to claim 1 or claim 2, wherein, In terms of mass% in terms of oxide conversion of the crystallized glass: The content of the K2O component is 0% to 5.0%.

5. The inorganic composition product according to claim 1 or claim 2, wherein In terms of mass% in terms of oxide conversion of the crystallized glass: The content of the Na2O component is 0% to 4.0%; The content of the MgO component is 0% to 4.0%; The content of the CaO component is 0% to 4.0%; The content of the SrO component is 0% to 4.0%; The content of the BaO component is 0% to 5.0%; The content of the ZnO component is 0% to 10.0%; and The content of the Sb2O3 component is 0% to 3.0%.

6. The inorganic composition product according to claim 1 or claim 2, wherein In terms of mass% in terms of oxide conversion of the crystallized glass: The content of the Nb2O5 component is 0% to 5.0%; The content of the Ta2O5 component is 0% to 6.0%; and The content of the TiO2 component is 0% or more and less than 1.0%.

7. The inorganic composition product according to claim 1 or claim 2, wherein, The glass transition temperature (Tg) of the glass before crystallization of the crystallized glass is 610 °C or lower.

8. The inorganic composition product according to claim 1 or claim 2, wherein, The plate thickness of the inorganic composition product is 0.1 mm to 2.0 mm.

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