Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
  • C03C10/0018—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing SiO2, Al2O3 and monovalent metal oxide as main constituents
  • C03C10/0027—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing SiO2, Al2O3 and monovalent metal oxide as main constituents containing SiO2, Al2O3, Li2O as main constituents
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C21/00—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface
  • C03C21/001—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions
  • C03C21/002—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions to perform ion-exchange between alkali ions
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/097—Glass compositions containing silica with 40% to 90% silica, by weight containing phosphorus, niobium or tantalum

Definitions

• the present invention relates to an inorganic composition article made of reinforced crystallized glass having a compressive stress layer on the surface.
• cover glass and housings to protect the displays of mobile electronic devices such as smartphones and tablet PCs, as protectors to protect the lenses of optical devices used in automobiles, as interior bezels and console panels, touch panel materials, smart keys, and more. These devices must be used in harsh environments, and so there is an increasing demand for glass with higher strength.
• Chemically strengthened glass has traditionally been used as a material for protective components and other applications.
• conventional chemically strengthened glass has been problematic due to the high number of accidents involving breakage when mobile devices such as smartphones are dropped.
• crystallized glass that is stronger and less likely to break when dropped.
• Patent Document 1 discloses the material composition of a chemically strengthenable crystallized glass substrate for information recording media. It is stated that the ⁇ -cristobalite crystallized glass described in Patent Document 1 can be chemically strengthened and can be used as a high-strength material substrate. However, crystallized glass for information recording media, such as substrates for hard disks, was not designed for use in harsh environments.
• Patent Document 2 discloses a microcrystalline glass product with excellent mechanical properties, the main crystal phase of which is lithium silicate and a quartz crystal phase, but does not envision a strength that would withstand harsh environments.
• the object of the present invention is to provide an inorganic composition article made of reinforced crystallized glass that is resistant to cracking when dropped, has high strength, and has the desired DOLzero ( ⁇ m) and compressive stress CS (MPa).
• the present invention provides the following: (Configuration 1) An inorganic composition article reinforced with glass-ceramics,
• the crystallized glass contains, as a main crystal phase, at least one selected from ⁇ -cristobalite and an ⁇ -cristobalite solid solution, In terms of oxide, mass %
• the content of SiO2 component is 50.0% to 75.0%,
• the content of Li 2 O component is 3.0% to 10.0%,
• the content of Al 2 O 3 component is 5.0% or more and less than 15.0%;
• the content of B2O3 component is more than 0% and 10.0% or less ;
• the content of the P2O5 component is more than 0% and 10.0% or less,
• the mass ratio SiO 2 /(B 2 O 3 +Li 2 O) is 3.0 to 10.0;
• the inorganic composition article has a compressive stress layer on a surface thereof and has a four-point bending strength of 760 MPa or more.
• the crystallized glass contains, in terms of oxide, The content of ZrO2 component is more than 0% and 10.0% or less, 2.
• the crystallized glass contains, in terms of oxide, K2O content is 0% to 5.0% 3.
• the inorganic composition article according to claim 1 or 2 (Configuration 4)
• the crystallized glass contains, in terms of oxide, The content of Na 2 O 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%, ZnO content is 0% to 10.0%, Sb 2 O 3 content is 0% to 3.0%
• the inorganic composition article according to any one of configurations 1 to 3, (Configuration 5)
• the crystallized glass contains, in terms of oxide,
• the content of Nb 2 O 5 component is 0% to 5.0%
• the content of Ta 2 O 5 component is 0% to 6.0%, 5.
• Configuration 6 The inorganic composition article 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.
• the present invention by controlling the amount of LiO2 and adjusting the amount of SiO2 and Al2O3 , it is possible to easily and stably manufacture an inorganic composition article related to crystallized glass having high impact resistance. In addition, it is possible to provide an inorganic composition article having high strength and a desired DOLzero ( ⁇ m) and compressive stress CS (MPa).
• the "inorganic composition article” (hereinafter, simply referred to as “article") is composed of an inorganic composition material such as glass, crystallized glass, ceramics, or a composite material of these.
• the article of the present invention includes, for example, an article obtained by forming these inorganic materials into a desired shape by processing or synthesis through a chemical reaction.
• a green compact obtained by crushing an inorganic material and then applying pressure, and a sintered body obtained by sintering the green compact.
• the shape of the article obtained here is not limited by smoothness, curvature, size, etc. For example, it may be a plate-shaped substrate, a molded body with curvature, or a three-dimensional structure with a complex shape.
• inorganic composition materials that have been chemically reinforced.
• the inorganic composition article of the present invention can be used as a protective material for devices, taking advantage of the fact that it is a glass-based material with high strength. It can be used as cover glass or housing for smartphones, or as a component for portable electronic devices such as tablet PCs or wearable devices, or as a component for protective protectors or head-up display substrates used in transport vehicles such as cars and airplanes. It can also be used for other electronic devices and machinery, building components, solar panel components, projector components, cover glass (windshield) for glasses and watches, etc.
• the inorganic composition article of the present invention and the crystallized glass serving as its base material contain at least one type of crystal phase selected from ⁇ -cristobalite and ⁇ -cristobalite solid solution as the main crystal phase.
• the crystallized glass in which these crystal phases precipitate has high mechanical strength.
• the term "main crystalline phase" as used herein corresponds to the crystalline phase that is most abundant in the glass-ceramics as determined from the peaks of the X-ray diffraction pattern.
• oxide equivalent refers to the amount of oxide of each component contained in the crystallized glass expressed as mass% when it is assumed that all the crystallized glass constituent components are decomposed and converted to oxide, and the total mass of the oxide is 100 mass%.
• A% to B% means A% or more and B% or less.
• the reinforced crystallized glass of the inorganic composition article according to the first embodiment of the present invention and the crystallized glass serving as the base material thereof are In terms of oxide, mass %
• the content of SiO2 component is 50.0% to 75.0%, The content of Li 2 O component is 3.0% to 10.0%, The content of Al 2 O 3 component is 5.0% or more and less than 15.0%;
• the content of B2O3 component is more than 0% and 10.0% or less ;
• the content of the P2O5 component is more than 0% and 10.0% or less, Mass ratio SiO 2 /(B 2 O 3 +Li 2 O) is 3.0 to 10.0 It is.
• the above composition allows for chemical strengthening, providing a strengthened crystallized glass with high strength and the desired DOLzero ( ⁇ m) and compressive stress CS (MPa).
• composition ranges of each component that constitutes the crystallized glass that serves as the base material of the present invention are described below.
• the SiO2 component is an essential component necessary for forming one or more selected from ⁇ -cristobalite and ⁇ -cristobalite solid solution.
• the content of the SiO2 component is 75.0% or less, an excessive increase in viscosity and a deterioration in meltability can be suppressed, and when the content is 50.0% or more, a deterioration in devitrification can be suppressed.
• the upper limit is 74.0% or less, 73.0% or less, 72.0% or less, or 70.0% or less, and preferably, the lower limit is 55.0% or more, 58.0% or more, or 60.0% or more.
• the Li2O component is a component that improves the meltability of the base glass, and when the amount of the Li2O component is 3.0% or more, the effect of improving the meltability of the base glass can be obtained, and when the amount of the Li2O component is 10.0% or less, the increase in the generation of lithium disilicate crystals can be suppressed.
• the Li2O component is a component that participates in chemical strengthening.
• the lower limit is 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, or 5.5% or more.
• the upper limit is 9.0% or less, and may be, for example, 8.5% or less, or 8.0% or less.
• the Al2O3 component is a suitable component for improving the mechanical strength of the crystallized glass.
• the content of the Al2O3 component is less than 15.0%, the deterioration of meltability and devitrification can be suppressed, and when the content is 5.0% or more, the decrease in mechanical strength can be suppressed.
• the upper limit is 14.5% or less, 14.0% or less, 13.5% or less, or 13.0% or less, and the lower limit can be 5.5% or more, 5.8% or more, 6.0% or more, 6.5% or more, or 8.0% or more.
• the B 2 O 3 component is a component suitable for lowering the glass transition temperature of the crystallized glass, and by controlling the amount of this component to 10.0% or less, it is possible to suppress the deterioration of the chemical durability.
• the upper limit is 8.0% or less, 7.0% or less, 5.0% or less, or 4.0% or less.
• the lower limit is more than 0%, and preferably 0.001% or more, 0.01% or more, 0.05% or more, 0.10% or more, or 0.30% or more.
• the ZrO2 component is a component that can improve the mechanical strength, and if the amount thereof is 10.0% or less, the deterioration of the meltability can be suppressed.
• the upper limit is 10.0% or less, 9.0% or less, 8.5% or less, or 8.0% or less, and preferably, the lower limit is more than 0%, 1.0% or more, 1.5% or more, or 2.0% or more.
• the compressive stress on the surface increases when strengthened.
• the lower limit of [Al2O3 + ZrO2 ] is 10.0% or more, 11.0% or more, 12.0% or more, or 13.0% or more.
• the upper limit of [Al 2 O 3 +ZrO 2 ] is preferably set to 22.0% or less, 21.0% or less, 20.0% or less, or 19.0% or less.
• the mass ratio SiO 2 /(B 2 O 3 +Li 2 O) is 3.0 to 10.0. By setting this mass ratio to 3.0 to 10.0, it contributes to lowering the viscosity of the glass, making it easier to prepare the glass, and also increases the amount of alkali ions exchanged during chemical strengthening, making it possible to prepare strengthened crystallized glass with the desired CS30 (compressive stress at a depth of 30 ⁇ m from the outermost surface).
• the lower limit of the mass ratio SiO2 /( B2O3 + Li2O ) is preferably 3.5 or more, more preferably 4.64 or more, and the upper limit of the mass ratio SiO2 /( B2O3 + Li2O ) is preferably 9.5 or less, more preferably less than 8.6.
• the lower limit of [ SiO2 + Li2O + Al2O3 + B2O3 ] is preferably 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, but can be, for example , less than 100 % or 99% or less.
• the P 2 O 5 component is an essential component that can be added to act as a crystal nucleation agent for glass.
• the amount of the P 2 O 5 component is 10.0% or less, it is possible to suppress the deterioration of the devitrification tendency of the glass and the phase separation of the glass.
• the upper limit is 8.0% or less, 6.0% or less, 5.0% or less, or 4.0% or less
• the lower limit is more than 0%, for example, 0.5% or more, 1.0% or more, or 1.5% or more.
• the K 2 O component is an optional component involved in chemical strengthening when the content exceeds 0%.
• the lower limit of the K 2 O component can be 0% or more, more than 0%, 0.1% or more, 0.3% or more, or 0.5% or more.
• the upper limit of the K 2 O content can be preferably set at 5.0% or less, 4.0% or less, 3.5% or less, or 3.0% or less.
• the Na 2 O component is an optional component involved in chemical strengthening when it is contained in an amount exceeding 0%. By making the Na 2 O component 4.0% or less, it is possible to easily obtain a desired crystal phase.
• the upper limit of the Na 2 O component can be 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 Na 2 O component can be 0% or more.
• the MgO component, CaO component, SrO component, BaO component, and ZnO component are optional components that improve low-temperature melting properties when their content exceeds 0%, and can be contained within a range that does not impair the effects of the present invention. Therefore, the upper limit of the MgO component can be preferably set to 4.0% or less, 3.5% or less, 3.0% or less, or 2.5% or less.
• the lower limit of the MgO component can be preferably set to 0% or more, more than 0%, 0.3% or more, or 0.4% or more.
• the upper limit of the CaO 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 CaO component can be set to 0% or more.
• 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.
• 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.
• the upper limit of the ZnO component can be preferably set to 10.0% or less, 9.0% or less, 8.5% or less, 8.0% or less, or 7.5% or less.
• the lower limit of the ZnO component can be preferably set to 0% or more, more than 0%, 0.5% or more, or 1.0% or more.
• the crystallized glass may or may not contain each of the Nb 2 O 5 component, the Ta 2 O 5 component, and the TiO 2 component, as long as the effects of the present invention are not impaired.
• the Nb2O5 component is an optional component that improves the mechanical strength of the crystallized glass when it is contained in an amount exceeding 0%.
• the upper limit of the Nb2O5 component is preferably 5.0% or less, 4.0% or less, 3.5% or less, or 3.0% or less.
• the lower limit of the Nb2O5 component is 0% or more.
• Ta2O5 component is an optional component that improves the mechanical strength of the crystallized glass when it is contained in an amount exceeding 0%.
• the upper limit of 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 Ta2O5 component can be set to 0% or more.
• the TiO2 component is an optional component that improves the chemical durability of the crystallized glass when it is contained in an amount of more than 0%.
• the upper limit of the TiO2 component 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.
• the crystallized glass may or may not contain La2O3 , Gd2O3 , Y2O3 , WO3 , TeO2 , and Bi2O3 , as long as the effect of the present invention is not impaired.
• the blending amount of each of these components can be 0% to 2.0 %, 0% to less than 2.0%, or 0% to 1.0 %.
• the crystallized glass may or may not contain other components not mentioned above, as long as they do not impair the properties of the crystallized glass of the present invention.
• metal components such as Yb, Lu, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo (including oxides of these metals).
• Sb 2 O 3 may be contained as a clarifier for glass.
• the Sb 2 O 3 component 3.0% or less, it is possible to suppress deterioration of transmittance in the short wavelength region of the visible light region. Therefore, the upper limit can be preferably made 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, and even more preferably 0.6% or less.
• the lower limit of the Sb 2 O 3 component can be made 0% or more.
• a fining agent for glass in addition to Sb2O3 , one or more selected from the group consisting of SnO2 , CeO2 , As2O3 , F, NOx and SOx may or may not be included.
• the upper limit of the content of the fining agent can be preferably set to 2.0% or less, more preferably 1.0% or less, and most preferably 0.6% or less.
• the compressive stress CS (MPa) of the compressive stress layer of the inorganic composition article is preferably 550 MPa or more, more preferably 600 MPa or more, and even 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, it is possible to suppress the progress of cracks and increase the mechanical strength.
• the compressive stress CS (MPa) can be measured by the method described in the Examples.
• the central tensile stress CT (MPa) is an index of the degree of strengthening of glass by chemical strengthening. If the value of CT is high, the fragments when the glass breaks tend to be small and shards. Therefore, for the impact resistance of the glass, the lower limit of the central tensile stress CT (MPa) is 70 MPa or more, preferably 75 MPa or more, more preferably 80 MPa or more, and even more preferably 85 MPa or more.
• the upper limit is 200 MPa or less, preferably 150 MPa or less, and more preferably 120 MPa or less. By having such a central tensile stress, it is possible to obtain a desired strengthened crystallized glass by chemical strengthening.
• the central tensile stress CT (MPa) can be measured by the method described in the Examples.
• the thickness DOLzero ( ⁇ m) of the compressive stress layer depends on the thickness of the inorganic composition article, but can be 8.0 ⁇ m to 500 ⁇ m. More preferably, it can be 9.5 ⁇ m to 440 ⁇ m, more preferably 20 ⁇ m to 400 ⁇ m, more preferably 30 ⁇ m to 350 ⁇ m, more preferably 50 ⁇ m to 300 ⁇ m, and even more preferably 60 to 120 ⁇ m.
• DOLzero can be 8.0 to 25 ⁇ m.
• the upper limit of DOLzero can be, for example, 25 ⁇ m or less, 22 ⁇ m or less, or 20 ⁇ m or less.
• the lower limit of DOLzero can be, for example, 8.0 ⁇ m or more, 8.5 ⁇ m or more, or 9.5 ⁇ m or more.
• the DOLzero can be 160 to 500 ⁇ m.
• the upper limit of DOLzero can be, for example, 500 ⁇ m or less, 440 ⁇ m or less, or 400 ⁇ m or less.
• the lower limit of DOLzero can be, for example, 160 ⁇ m or more, 180 ⁇ m or more.
• the lower limit of the thickness DOLzero of the compressive stress layer is 8.0% or more, preferably 9.0% or more, more preferably 9.5% or more, more preferably 10% or more, and even more preferably 15% or more, relative to the plate thickness of the inorganic composition article.
• the upper limit of the thickness DOLzero of the compressive stress layer is 25.0% or less, preferably 22.0% or less, and more preferably 20.0% or less, relative to the plate thickness of the inorganic composition article.
• the thickness DOLzero ( ⁇ m) of the compressive stress layer can be measured by the method described in the Examples.
• 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, more preferably 0.4 mm or more, and even more preferably 0.5 mm or more
• the upper limit of the thickness of the substrate is preferably 2.0 mm or less, more preferably 1.5 mm or less, more preferably 1.1 mm or less, more preferably 1.0 mm or less, more preferably 0.9 mm or less, and even more preferably 0.8 mm or less.
• plate thickness of an inorganic composition article refers to the distance between two opposing principal surfaces arranged approximately parallel to each other when the inorganic composition article is shaped like a plate having a finite thickness.
• the inorganic composition article is shaped like a strip having a finite thickness, it refers to the distance between two approximately rectangular planes.
• [Compressive stress CS (MPa)] x [thickness of compressive stress layer DOLzero ( ⁇ m)] / [thickness of substrate t (mm)] is an index of impact resistance). That is, the lower limit of the [compressive stress CS (MPa)] ⁇ [thickness of the compressive stress layer DOLzero ( ⁇ m)] / [thickness of the substrate t (mm)] of the strengthened crystallized glass of the present invention is preferably 100 or more, more preferably 110 or more, and even more preferably 120 or more.
• the upper limit of [compressive stress CS (MPa)] ⁇ [thickness of compressive stress layer DOLzero ( ⁇ m)] / [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 in such a numerical range, it is possible to obtain a crystallized glass with high strength by chemical strengthening.
• the four-point bending strength (bending stress) of the inorganic composition article is 760 MPa or more, and can be 800 MPa or more, 850 MPa or more, 900 MPa or more, 950 MPa or more, 1000 MPa or more, 1050 MPa or more, 1100 MPa or more, 1150 MPa or more, or 1200 MPa or more.
• the four-point bending strength is measured by the method described in the Examples.
• crystallized glass of the inorganic composition article according to an embodiment of the present invention (hereinafter simply referred to as "crystallized glass”) can be produced by the following method. That is, the raw materials are mixed uniformly so that each component falls within a specified content range, and the mixture is melt-molded to produce raw glass. This raw glass is then crystallized to produce crystallized glass.
• the glass transition temperature Tg of the glass before crystallization of the crystallized glass is preferably 610°C or less, more preferably 600°C or less, and even more preferably 590°C or less.
• the heat treatment for crystal precipitation may be performed at a single temperature stage or at two temperature stages.
• a nucleation step is first performed by heat treatment at a first temperature, and after this nucleation step, a crystal growth step is performed by heat treatment at a second temperature higher than that of the nucleation step.
• 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, and more preferably 180 minutes to 1440 minutes.
• 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 minutes to 600 minutes, more preferably 60 minutes to 400 minutes.
• the nucleation step and the crystal growth step are carried out consecutively at a single temperature step.
• the temperature is raised to a predetermined heat treatment temperature, and after reaching the heat treatment temperature, the temperature is maintained for a certain period of time, and then the temperature is lowered.
• the heat treatment temperature is preferably 600° C. to 800° C., more preferably 630° C. to 770° C.
• the holding time at the heat treatment temperature is preferably 30 minutes to 500 minutes, more preferably 60 minutes to 400 minutes.
• Methods for forming a compressive stress layer in an inorganic composition article include, for example, a chemical strengthening method in which an alkali component present in the surface layer of crystallized glass is subjected to an exchange reaction with an alkali component having a larger ionic radius to form a compressive stress layer in the surface layer.
• Other methods include a thermal strengthening method in which crystallized glass is heated and then rapidly cooled, and an ion implantation method in which ions are implanted into the surface layer of crystallized glass.
• the inorganic composition article of the present invention can be produced, for example, by the following chemical strengthening method.
• the crystallized glass is brought into contact with or immersed in a molten salt of a salt containing potassium, sodium, and lithium, such as a mixed salt or composite salt of potassium nitrate (KNO 3 ), sodium nitrate (NaNO 3 ), or lithium nitrate (LiNO 3 ).
• a molten salt of a salt containing potassium, sodium, and lithium such as a mixed salt or composite salt of potassium nitrate (KNO 3 ), sodium nitrate (NaNO 3 ), or lithium nitrate (LiNO 3 ).
• KNO 3 potassium nitrate
• NaNO 3 sodium nitrate
• LiNO 3 lithium nitrate
• the steel is contacted or immersed for 1 to 1440 minutes, preferably 15 to 500 minutes, more preferably 30 to 300 minutes, in a mixed salt of potassium and sodium, sodium salt, or a mixed salt of potassium, sodium, and lithium heated at 350 ° C. to 550 ° C.
• the steel is contacted or immersed for 1 to 1440 minutes, preferably 60 to 600 minutes, 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.
• a two-stage chemical strengthening treatment for example, it is desirable to use a single bath or a mixed bath of potassium (KNO 3 ), sodium (NaNO 3 ), or lithium (LiNO 3 ) in the first stage treatment, and a molten salt of a salt containing potassium, sodium, and lithium, such as a mixed salt or a composite salt of potassium nitrate (KNO 3 ), sodium nitrate (NaNO 3 ), and lithium nitrate (LiNO 3 ), in the second stage treatment.
• KNO 3 potassium
• NaNO 3 sodium nitrate
• LiNO 3 lithium nitrate
• the material is contacted with or immersed in a mixed salt containing potassium and sodium, a mixed salt containing potassium, sodium, and lithium, a mixed salt containing sodium, or 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 for 1 to 1440 minutes, preferably 30 to 500 minutes.
• Examples 1 to 27 and Comparative Example 1 Preparation of Inorganic Composition Articles As raw materials for each component of the crystallized glass, raw materials such as oxides, hydroxides, carbonates, nitrates, fluorides, chlorides, and metaphosphate compounds corresponding thereto were selected, and these raw materials were weighed and uniformly mixed to obtain the compositions shown in Tables 1 to 4.
• the mixed raw materials were then 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 to homogenize it, and the temperature was then lowered to 1000°C to 1450°C before it was poured into a metal mold and slowly cooled to produce base glass.
• the resulting base glass was then heated under the crystallization conditions for the nucleation process and crystal growth process listed in Tables 1 to 4 to produce crystallized glass.
• the crystal phase of the crystallized glass was determined from the angle of the peak appearing in the X-ray diffraction pattern using an X-ray diffraction analyzer (manufactured by Bruker, "D8Discover").
• X-ray diffraction analyzer manufactured by Bruker, "D8Discover"
• a peak was observed at a position corresponding to the peak pattern of ⁇ -cristobalite and/or ⁇ -cristobalite solid solution, and it was determined that ⁇ -cristobalite and/or ⁇ -cristobalite solid solution had precipitated as the main crystal phase.
• Tg glass transition points of the glasses before crystallization in Examples 1 to 27 and Comparative Example 1 were measured in accordance with the Japan Optical Glass Industry Association standard JOGIS08-2019 "Method for measuring thermal expansion of optical glass.”
• Example 1 and Comparative Example 1 The crystallized glass prepared in Example 1 and Comparative Example 1 was cut and ground, and then face-to-face parallel polished to obtain a crystallized glass substrate so as to have the thickness shown in Tables 5 to 9.
• the crystallized glass substrate was used as a base material to obtain the chemically strengthened crystallized glass substrates of Examples 1-1 to 1-29 and Comparative Example 1-1.
• Examples 1-1 to 1-29 the crystallized glass of Example 1 was used and chemically strengthened under the strengthening conditions shown in Tables 5 to 9.
• the crystallized glass was polished to a width of 72 mm, a length of 135 mm, and a thickness shown in Tables 5 to 9.
• Comparative Example 1-1 the crystallized glass of Comparative Example 1 was used and chemical strengthening treatment was performed under the strengthening conditions shown in Table 9.
• Example 1-1 first row of strengthening conditions
• Example 1-2 second row of chemical strengthening
• “KNO 3 , 400° C. ⁇ 300 min” indicates that the specimen was immersed in a single potassium salt bath at 400° C. for 300 minutes.
• the optical path difference is expressed as ⁇ (nm), the glass thickness as d (mm), and the stress as F (MPa).
• the compressive stress CS (MPa) of the compressive stress layer was measured using a glass surface stress meter (manufactured by Orihara Seisakusho, "FSM-6000LE series”).
• a light source with a wavelength of 365 nm was used as the measurement light source, and the refractive index value at a wavelength of 365 nm or less was calculated using a quadratic approximation formula from the measured values of the refractive index at the wavelengths of C line, d line, F line, and g line in accordance with the V-block method defined in JIS B 7071-2:2018.
• the photoelastic constant value used in the CS measurement was calculated using a quadratic approximation formula from 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 of Comparative Example 1-1 was the value of Example 2 of Patent Document 2.
• the depth DOLzero ( ⁇ m) and central tensile stress (CT) when the compressive stress of the compressive stress layer was 0 MPa were measured using a scattered light photoelastic stress meter (manufactured by Orihara Seisakusho, "SLP-1000").
• SLP-1000 scattered light photoelastic stress meter
• a light source with a wavelength of 405 nm was used for Examples 1-1 to 1-9
• a light source with a wavelength of 518 nm was used for Examples 1-10 to 1-29.
• the refractive index at a wavelength of 405 nm or 518 nm was calculated using a quadratic approximation equation from the measured refractive index values at the wavelengths of C line, d line, F line, and g line in accordance with the V-block method specified in JIS B 7071-2:2018.
• the "substrate thickness” shown in Tables 5 to 9 is the thickness (mm) of the chemically strengthened crystallized glass substrate
• the "CS ⁇ DOLzero / substrate thickness” shown in Tables 5 to 9 is the value obtained by dividing DOLzero ( ⁇ m) by the thickness (mm) of the chemically strengthened crystallized glass substrate and multiplying the value by the compressive stress CS (MPa).
• the photoelastic constant at wavelengths of 405 nm or 518 nm used in DOLzero and CT measurements can be calculated using a quadratic approximation formula from the measured values of the photoelastic constant at wavelengths of 435.8 nm, 546.1 nm, and 643.9 nm.
• a value of 31.0 was used in Examples 1-1 to 1-9, and 30.1 was used in Examples 1-10 to 1-29.
• the CS value in Comparative Example 1-1 was the value in Example 2 of Patent Document 2.

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