TW202024671A - Crystallized glass substrate the hardness of the outermost surface at a pressed depth of 20 nm is 7.50 GPa to 9.50 GPa - Google Patents

Abstract

The present invention is a crystallized glass substrate having a compressive stress layer on the surface. When the depth corresponding to the surface compressive stress of the compressive stress layer being 0 MPa is set to the stress depth DOLzero, in the compressive stress layer, the gradient A of the surface compressive stress from the outermost surface to the depth of 6[mu]m is 50.0MPa/[mu]m to 110.0MPa/[mu]m, and the gradient B of the surface compressive stress from the depth of (the aforementioned stress depth DOLzero-10[mu]m) to the aforementioned stress depth DOLzero is 2.5MPa/[mu]m to 15.0MPa/[mu]m. The hardness of the aforementioned outermost surface at a pressed depth of 20 nm is 7.50 GPa to 9.50 GPa.

Description

Crystallized glass substrate

The invention relates to a crystallized glass substrate with a compressive stress layer on the surface.

In portable electronic devices such as smart phones and tablet PCs (personal computers), glass covers are used to protect displays. In addition, a protective lens (protector) for protecting the lens is also used in the optical equipment for the vehicle. Furthermore, in recent years, it has also been sought to be used as an outer casing of an electronic device. Then, in order to allow these machines to withstand more rigorous use, the requirements for materials with higher hardness have gradually increased.

In the past, chemically strengthened glass was used as a material for protecting members. However, since conventional chemically strengthened glass is very weak to cracks that enter vertically from the glass surface, many damage accidents occur when the portable device is dropped, which becomes a problem. Furthermore, there is a risk of injury when it is crushed into pulverized powder when damaged. Seek to become large fragments when destroyed.

Patent Document 1 discloses a crystallized glass substrate for information recording media. When the crystallized glass substrate is chemically strengthened, a sufficient compressive stress value cannot be obtained. [Prior Technical Literature] [Patent Literature]

Patent Document 1: JP 2014-114200 A.

[The problem to be solved by the invention]

The present invention is made in view of the above-mentioned problems. The object of the present invention is to obtain a crystallized glass substrate that is hard and not easily broken.

In order to solve the above-mentioned problems, the present inventors have devoted themselves to the results of repeated experiments and found that a crystallized glass substrate can be obtained, which is chemically strengthened by a mixed acid, thereby increasing the surface compressive stress of the compressive stress layer and reducing the central compressive stress. The impact resistance is high, and even if it is damaged by impact, it is difficult to break (explosive damage), and the present invention has been completed. Specifically, the present invention provides the following.

(Configuration 1) A crystallized glass substrate having a compressive stress layer on the surface; when the depth at which the surface compressive stress of the compressive stress layer is 0 MPa is the stress depth DOLzero, the compressive stress layer is from the outermost surface to The gradient A of the surface compressive stress at a depth of up to 6μm is 50.0MPa/μm to 110.0MPa/μm; the gradient B of the surface compressive stress from the depth (the aforementioned stress depth DOLzero-10μm) to the aforementioned stress depth DOLzero is 2.5MPa/ μm to 15.0MPa/μm; the hardness of the indentation depth 20nm of the aforementioned outermost surface is 7.50GPa to 9.50GPa. (Configuration 2) A crystallized glass substrate having a compressive stress layer on the surface; when the depth at which the surface compressive stress of the compressive stress layer is 0 MPa is the stress depth DOLzero, the compressive stress layer is from the outermost surface to The gradient A of the surface compressive stress at a depth of up to 6μm is 50.0MPa/μm to 110.0MPa/μm; the gradient B of the surface compressive stress from the depth (the aforementioned stress depth DOLzero-10μm) to the aforementioned stress depth DOLzero is 2.5MPa/ μm to 15.0MPa/μm; the hardness of the indentation depth 100nm of the aforementioned outermost surface is 8.00GPa to 9.50GPa. (Configuration 3) A crystallized glass substrate having a compressive stress layer on the surface; when the depth at which the surface compressive stress of the compressive stress layer is 0 MPa is the stress depth DOLzero, the compressive stress layer is from the outermost surface to The gradient A of the surface compressive stress at a depth of up to 6μm is 50.0MPa/μm to 110.0MPa/μm; the gradient B of the surface compressive stress from the depth (the aforementioned stress depth DOLzero-10μm) to the aforementioned stress depth DOLzero is 2.5MPa/ μm to 15.0 MPa/μm; the surface compressive stress CS of the outermost surface of the compressive stress layer is 900.0 MPa to 1200.0 MPa. (Configuration 4) The crystallized glass substrate as described in Configuration 1 or 2, wherein the stress depth DOLzero is 30.0 μm to 70.0 μm; the surface compressive stress CS of the outermost surface of the compressive stress layer is 870.0 MPa to 1150.0 MPa; central compression The stress CT is 35.0MPa to 70.0MPa. (Constitution 5) The crystallized glass substrate as described in Compositions 1 to 4, when converted to oxide weight%, contains: SiO ₂ component 40.0% to 70.0%; Al ₂ O ₃ component 11.0% to 25.0%; Na ₂ O component 5.0% to 19.0%; K ₂ O component 0% to 9.0%; one or more selected from MgO component and ZnO component 1.0% to 18.0%; CaO component 0% to 3.0%; and TiO ₂ component 0.5% To 12.0%. (Configuration 6) The crystallized glass substrate as described in Configurations 1 to 5, wherein the thickness of the crystallized glass substrate is 0.1 mm to 1.0 mm.

With the present invention, a hard and hard to crack crystallized glass substrate can be obtained.

The crystallized glass substrate of the present invention can be used for display or lens glass covers of electronic equipment, lens protection mirrors for optical equipment used in vehicles, outer frame members or housings, optical lens materials, and various other members.

Hereinafter, embodiments and examples of the crystallized glass substrate of the present invention will be described in detail, but the present invention is not limited to the following embodiments and examples, and can be implemented with appropriate changes within the scope of the purpose of the present invention.

[Crystalized Glass Substrate] The crystallized glass substrate of the present invention uses crystallized glass as a base material (also referred to as a crystallized glass base material), and has a compressive stress layer on the surface. The compressive stress layer can be formed by subjecting the crystallized glass base material to ion exchange treatment. The compressive stress layer is formed with a predetermined thickness from the outermost surface of the substrate on the inner side, and the compressive stress is the highest on the outermost surface and decreases to zero toward the inner side.

Fig. 1 is a diagram showing an example of changes in the compressive stress (MPa) from the depth (μm) of the outermost surface in the compressive stress layer of the surface portion of the crystallized glass substrate of the present invention. A depth of zero indicates the outermost surface. The compressive stress of the outermost surface (also referred to as the uppermost surface compressive stress) is represented by CS, and the depth of the compressive stress layer (also referred to as stress depth) when the compressive stress is 0 MPa is represented by DOLzero. In Figure 1, after the compressive stress decreases sharply (large slope) from the outermost surface to the inner side, the compressive stress decreases slowly (with a small slope).

Specifically, the compressive stress gradient A from the outermost surface to the depth of 6 μm is 50.0 MPa/μm to 110.0 MPa/μm, preferably 60.0 MPa/μm to 105.0 MPa/μm or 70.0 MPa/μm to 100.0 MPa /Μm. The compressive stress gradient B from the depth of (stress depth DOLzero-10μm) to the stress depth DOLzero is 2.5MPa/μm to 15.0MPa/μm, preferably 3.0MPa/μm to 13.0MPa/μm or 3.5MPa/μm To 12.0MPa/μm. In Figure 1, when the compressive stress from the outermost surface to a depth of 6μm is CS1, the gradient A can be obtained by (CS-CS1)/6. When the compressive stress of the part shallow 10 μm from the stress depth DOLzero is CS2, the gradient B can be obtained by CS2/10.

The compressive stress CS of the outermost surface of the compressive stress layer is generally 870.0 MPa to 1200.0 MPa, for example, 900.0 MPa to 1200.0 MPa, 930. MPa to 1150.0 MPa, 950.0 MPa to 1100.0 MPa, or 960.0 MPa to 1050.0 MPa.

The compression depth DOLzero obtained by curve analysis may be 30.0 μm to 70.0 μm, for example, it may be 35.0 μm to 60.0 μm or 38.0 μm to 58.0 μm.

The compression depth DOL obtained by linear analysis may be 40.0 μm to 80.0 μm, for example, it may be 45.0 μm to 75.0 μm or 50.0 μm to 70.0 μm.

The central stress CT obtained by curve analysis may be 35.0 MPa to 70.0 MPa, for example, it may be 38.0 MPa to 65.0 MPa or 40.0 MPa to 60.0 MPa.

The hardness of the indentation depth of 20 nm of the crystallized glass substrate is preferably 7.50 GPa to 9.50 GPa, more preferably 7.80 GPa to 9.30 GPa, and still more preferably 8.00 GPa to 9.10 GPa. The hardness when the crystallized glass substrate is pressed from the outermost surface to a depth of 50 nm (hardness at a depth of 50 nm) is preferably 7.50 GPa to 9.50 GPa, more preferably 7.80 GPa to 9.30 GPa, and still more preferably 8.00 GPa to 9.10 GPa. The hardness at an indentation depth of 100 nm of the crystallized glass substrate is preferably 8.00 GPa to 9.50 GPa, more preferably 8.30 GPa to 9.30 GPa, and still more preferably 8.50 GPa to 9.10 GPa. The hardness of the crystallized glass substrate at an indentation depth of 20 nm is preferably 8.00 GPa to 9.50 GPa, more preferably 8.30 GPa to 9.30 GPa, and still more preferably 8.50 GPa to 9.10 GPa. The above-mentioned hardness can be obtained by the method described in the Examples.

If the compressive stress layer has the above-mentioned stress gradients A, B, hardness, and/or the outermost surface compressive stress CS, the substrate is difficult to break. The stress depth, stress gradient, hardness, surface compressive stress, and central stress system can be adjusted by adjusting the composition, the thickness of the substrate, and the chemical strengthening conditions.

The lower limit of the thickness of the crystallized glass substrate is preferably 0.10 mm or more, more preferably 0.30 mm or more, more preferably 0.40 mm or more, and still more preferably 0.50 mm or more; the upper limit of the thickness of the crystallized glass substrate is preferably 1.00 mm Below, it is more preferably 0.90 mm or less, more preferably 0.70 mm or less, and still more preferably 0.60 mm or less.

Crystallized glass is a material with a crystalline phase and a glass phase, which is different from amorphous solids. Generally speaking, the crystalline phase of crystallized glass can use the angle of the peak appearing in the X-ray diffraction pattern of X-ray diffraction analysis and TEMEDX (Transmission electron microscopy energy-dispersive X-ray spectroscopy; Microscope X-ray energy dispersion analysis) to distinguish.

The crystallized glass contains, for example, MgAl ₂ O ₄ , MgTi ₂ O ₄ , MgTi ₂ O ₅ , Mg ₂ TiO ₄ , Mg ₂ SiO, MgAl ₂ Si ₂ O ₈ , Mg ₂ Al ₄ Si ₅ O ₁₈ and One or more selected from Mg ₂ TiO ₅ , MgSiO ₃ , NaAlSiO ₄ , FeAl ₂ O ₄ and these solid solutions.

The average crystal diameter in the crystallized glass can be, for example, 4 nm to 15 nm, 5 nm to 13 nm, or 6 nm to 10 nm. If the average crystal diameter is small, the polished surface roughness Ra can be smoothly processed to the order of several Å. In addition, the light transmittance becomes higher.

The composition range of each component constituting the crystallized glass is as follows. In this specification, unless otherwise specified, the content of each component is expressed in weight% converted to oxide. Here, the term "converted to oxides" means that assuming that all components of the crystallized glass are decomposed into oxides, when the total weight of the oxides is set to 100% by weight, the crystallized glass contains The amount of oxide of each component is expressed in% by weight.

The crystallized glass as the base material preferably contains: SiO ₂ component 40.0% to 70.0%; Al ₂ O ₃ component 11.0% to 25.0%; Na ₂ O component 5.0% to 19.0 when converted to oxide weight% %; K ₂ O component 0% to 9.0%; one or more selected from MgO component and ZnO component 1.0% to 18.0%; CaO component 0% to 3.0%; and TiO ₂ component 0.5% to 12.0%.

The SiO ₂ component is more preferably 45.0% to 65.0%, and still more preferably 50.0% to 60.0%. The Al ₂ O ₃ component more preferably contains 13.0% to 23.0%. More preferably, the Na ₂ O component contains 8.0% to 16.0%. It may also contain 9.0% or more or 10.5% or more. The K ₂ O component is more preferably 0.1% to 7.0%, and still more preferably 1.0% to 5.0%. One or more selected from the MgO component and the ZnO component more preferably contains 2.0% to 15.0%, still more preferably contains 3.0% to 13.0%, and particularly preferably contains 5.0% to 11.0%. One or more selected from the MgO component and the ZnO component may be the MgO component alone, the ZnO component alone, or both, but it is preferable to have only the MgO component. The content of CaO is more preferably 0.01% to 3.0%, and still more preferably 0.1% to 2.0%. The content of the TiO ₂ component is more preferably 1.0% to 10.0%, and even more preferably 2.0% to 8.0%. The crystallized glass may contain 0.01% to 3.0% (preferably 0.03% to 2.0%, and more preferably 0.05% to 1.0%) of one selected from Sb ₂ O ₃ , SnO ₂ and CeO ₂ the above. The above-mentioned compounding amounts can be appropriately combined.

One or more selected from SiO ₂ component, Al ₂ O ₃ component, Na ₂ O component, MgO component, and ZnO component, plus 90% or more of TiO ₂ component, preferably 95% or more, more preferably 98 % Or more, and more preferably 98.5% or more. One or more selected from SiO ₂ component, Al ₂ O ₃ component, Na ₂ O component, K ₂ O component, MgO component, and ZnO component. CaO component, TiO ₂ component and Sb ₂ O ₃ component can be added. The selected one or more of the SnO ₂ component and the CeO ₂ component is 90% or more, preferably 95% or more, more preferably 98% or more, and still more preferably 99% or more. These ingredients can also account for 100%.

The crystallized glass may contain or not contain ZrO _{2 as long as it} does not impair the effectiveness of the present invention. The blending amount can be 0% to 5.0%, 0% to 3.0%, or 0% to 2.0%. In addition, the crystallized glass may contain or not contain B ₂ O ₃ components, P ₂ O ₅ components, BaO components, FeO components, SnO ₂ components, and Li ₂ O components, within the range that does not impair the effectiveness of the present invention. , SrO component, La ₂ O ₃ component, Y ₂ O ₃ component, Nb ₂ O ₅ component, Ta ₂ O ₅ component, WO ₃ component, TeO ₂ component, Bi ₂ O ₃ component. The blending amount can be 0% to 2.0%, 0 or more and less than 2.0%, or 0% to 1.0%.

The crystallized glass of the present invention, as a fining agent, in addition to the Sb ₂ O ₃ component, the SnO ₂ component, and the CeO ₂ component, it may also contain or not contain the As ₂ O ₃ component and the group consisting of F, Cl, NOx, and SOx One or more than two selected in the group. Among them, the upper limit of the content of the clarifying agent is preferably 0.5% or less, more preferably 0.2% or less, and particularly preferably 0.1% or less.

In addition, the crystallized glass as the base material preferably contains SiO ₂ component 43.0 mol% to 73.0 mol%; Al ₂ O ₃ component 4.0 mol% to 18.0 mol% in mole% converted to oxides. %; Na ₂ O component 5.0 mol% to 19.0 mol%; K ₂ O component 0 mol% to 9.0 mol%; 1 or more selected from MgO component and ZnO component 2.0 mol% to 22.0 mol% %; CaO component 0 mol% to 3.0 mol%; and TiO ₂ component 0.5 mol% to 11.0 mol%. One or more selected from SiO ₂ component, Al ₂ O ₃ component, Na ₂ O component, MgO component, and ZnO component can add TiO ₂ component at 90 mol% or more, preferably 95 mol% or more, More preferably, it is 98 mol% or more, and still more preferably 99 mol% or more.

As long as the crystallized glass of the present invention does not impair the characteristics of the crystallized glass of the present invention, other components not mentioned above may be added as necessary. For example, the crystallized glass (and substrate) of the present invention may be colorless and transparent, but the glass may be colored within a range that does not impair the characteristics of the crystallized glass.

Furthermore, since the respective components of Pb, Th, Tl, Os, Be, and Se tend to avoid the use of harmful chemical substances in recent years, it is preferable that these components are not contained substantially.

[Manufacturing method] The crystallized glass substrate of the present invention can be produced by the following method. That is, the raw materials are uniformly mixed and melted and molded to produce raw glass. Then, the raw glass is crystallized to produce a crystallized glass base material. Furthermore, the crystallized glass base material is chemically strengthened.

The raw glass is heat-treated and crystals are precipitated inside the glass. This heat treatment can be performed at a temperature of one stage or two stages. 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 the nucleation step. In the one-stage heat treatment, the nucleation step and the crystal growth step are continuously performed at the temperature of one stage. Generally, the temperature is raised to a predetermined heat treatment temperature, and after the heat treatment temperature is reached, the temperature is maintained for a certain period of time, and then the temperature is lowered. The first temperature of the two-stage heat treatment is preferably 600°C to 750°C. The holding time at the first temperature is preferably 30 minutes to 2000 minutes, more preferably 180 minutes to 1440 minutes. The second temperature of the two-stage heat treatment is preferably 650°C to 850°C. The holding time at the second temperature is preferably 30 minutes to 600 minutes, more preferably 60 minutes to 300 minutes. When the heat treatment is performed at a one-step temperature, the temperature of the heat treatment is preferably 600°C to 800°C, more preferably 630°C to 770°C. In addition, the holding time at the temperature of the heat treatment is preferably 30 minutes to 500 minutes, more preferably 60 minutes to 300 minutes.

For example, grinding and polishing can be used to produce a thin plate-like crystallized glass base material from the crystallized glass base material.

After that, ion exchange is performed by a chemical strengthening method, thereby forming a compressive stress layer on the crystallized glass base material.

The crystallized glass base material is chemically strengthened with a mixed molten salt of potassium salt and sodium salt (mixed bath), and the mixed bath is further chemically strengthened with a separate mixed molten salt of potassium salt (separate bath). Specifically, for example, contacting or immersing the crystallized glass base material in a salt containing potassium or sodium, for example, contacting or immersing in a mixed salt such as potassium nitrate (KNO ₃ ) and sodium nitrate (NaNO ₃ ) or a composite The salt is heated to 350°C to 600°C (preferably 380°C to 570°C, more preferably 400°C to 500°C, and more preferably 430°C to 490°C) in the molten salt for 100 minutes or more, for example, 200 minutes to 800°C The points are preferably 300 to 700 points, and more preferably 450 to 550 points. The mixing ratio of potassium salt and sodium salt is, for example, a weight ratio of 1:1 to 50:1, 1.5:1 to 30:1, 2:1 to 20:1, or 3:1 to 15:1. Furthermore, it is preferable to continue contacting or immersing in a salt containing potassium, such as contacting or immersing in heating potassium nitrate (KNO ₃ ) to 380°C to 550°C (more preferably 400°C to 500°C, and more preferably 430°C to 490°C) for a short time in molten salt, such as 1 minute or more, 3 minutes to 40 minutes, 4 minutes to 30 minutes, or 5 minutes to 20 minutes. In this way, by chemical strengthening, the component existing near the surface and the component contained in the molten salt undergo an ion exchange reaction. As a result, a compressive stress layer is formed on the surface. [Example]

Examples 1 and 2 As the raw materials for each component of crystallized glass, the corresponding raw materials for oxides, hydroxides, carbonates, nitrates, fluorides, chlorides, and partial oxide compounds were selected, and these raw materials were Weigh it so that it becomes the ratio of the following composition, and mix it uniformly. (Calculated as weight% of oxide) SiO ₂ component 54%, Al ₂ O ₃ component 18%, Na ₂ O component 12%, K ₂ O component 2%, MgO component 8%, CaO component 1%, TiO ₂ component 5%, 0.1% of Sb ₂ O ₃ content.

Then, put the mixed raw materials into a platinum crucible to melt. After that, the molten glass is stirred and homogenized, and then cast into a mold, slowly cooled to produce raw glass.

For nucleation and crystallization, a one-stage heat treatment (650°C to 730°C, 5 hours) is applied to the obtained raw glass to produce crystallized glass as a base material. The obtained crystallized glass was analyzed by a 200kV field emission type transmission electron microscope FE-TEM (JEM2100F manufactured by JEOL Ltd.), and as a result, precipitated crystals with an average crystal diameter of 6 nm to 9 nm were observed. Furthermore, the lattice image caused by the electron diffraction image was confirmed and analyzed by EDX (energy-dispersion X-ray analysis; X-ray energy dispersion analysis), and the crystal phases of MgAl ₂ O ₄ and MgTi ₂ O ₄ were confirmed . The average crystal diameter is determined by using a transmission electron microscope to obtain the crystal diameter of the crystal particles in the range of 180×180 nm ² and calculate the average value.

The prepared crystallized glass base material is cut and ground, and face-to-face parallel grinding is performed so that it becomes a substrate with a thickness of 0.61mm and 0.54mm. The base material of crystallized glass is colorless and transparent.

Chemical strengthening is performed on the crystallized glass base material that is ground in parallel to obtain a crystallized glass substrate. Specifically, in Example 1, after being immersed in a mixed molten salt of KNO ₃ and NaNO ₃ at a mixing ratio of KNO ₃ :NaNO ₃ =3:1 (weight ratio) at 460°C for 500 minutes, only KNO ₃ Soaked in molten salt at 460°C for 15 minutes. In Example 2, the chemical strengthening was performed in the same manner as in Example 1, except that the mixing ratio of KNO ₃ and NaNO ₃ was changed to KNO ₃ :NaNO ₃ =10:1 (weight ratio).

The following evaluations were performed on the obtained substrate. (1) Using the glass surface stress meter FSM-6000LE manufactured by Orihara Manufacturing Co., Ltd., the thickness of the compressive stress layer (stress depth DOLzero) of the crystallized glass substrate and the surface compressive stress value of the compressive stress layer from the outermost surface to DOLzero were measured. Determination. Calculated with the refractive index of the sample 1.54 and the optical elastic constant 29.658 [(nm/cm)/MPa]. Obtain the surface compressive stress gradient A (MPa/μm) from the outermost surface to the depth of 6μm and the surface compressive stress gradient B (MPa/μm) from the depth (stress depth DOLzero-10μm) to the stress depth DOLzero . The central compressive stress (CT) is obtained by curve analysis (Curve　analysis). Furthermore, the thickness of the compressive stress layer (stress depth DOL) is also obtained by linear analysis. The results are shown in Table 1.

(2) Using the Nano-indentation system (TI Premier) manufactured by Bruker, the hardness of the substrate was measured when it was indented from the outermost surface to depths of 20 nm, 50 nm, 100 nm, and 200 nm. The results are shown in Table 1.

(3) For the crystallized glass substrate, a ball drop test was performed using sandpaper by the following method. The falling ball test system simulates falling onto the pitch. Spread sandpaper with roughness #180 on the marble base, and place a crystallized glass substrate (length 15 cm x width 7 cm). Then, 16.5 g of SUS (Steel Special Use Stainless) iron balls were dropped onto the substrate from a height of 10 mm (1 cm) from the substrate. After falling, if the substrate is not damaged, increase the height by 10 mm (1 cm), and continue the same test until it fails. After destruction, observe the state of the fragments. The results are shown in Table 2. It is indicated by ○ when it is not broken, and × when it is broken.

The state of the fragments was evaluated based on the following criteria. The results are shown in Table 2. A: There are 4 or more fragments of 1 cm ² or more, or ¹ or more fragments of 10 cm ² or more. B: There are 1 to 3 fragments of 1 cm ² or more. C: There are zero fragments of 1 cm ² or more (all are small fragments of less than 1 cm ² ). It can be seen from Table 2 that the substrate of the present invention is hard and difficult to break, and even if broken, it is hard to break.

Comparative Examples 1 and 2 In Comparative Examples 1 and 2, amorphous glass was used. As the raw materials for each component of the glass, select the corresponding raw materials such as oxides, hydroxides, carbonates, nitrates, fluorides, chlorides, and partial oxide compounds, and set these raw materials to the following composition ratios Method of weighing and mixing evenly. (Comparative example 1 is converted to oxide weight%) SiO ₂ component 62.4%, Al ₂ O ₃ component 21%, Na ₂ O component 12%, K ₂ O component 0.1%, MgO component 1.5%, B ₂ O ₃ The composition is 2.9%, and the composition of Sb ₂ O ₃ is 0.1%. (Comparative Example 2 is converted to oxide weight%) SiO ₂ component 62.2%, Al ₂ O ₃ component 16%, Na ₂ O component 8.3%, K ₂ O component 5.7%, MgO component 4.8%, B ₂ O ₃ The composition is 2.9%, and the composition of Sb ₂ O ₃ is 0.1%.

Then, put the mixed raw materials into a platinum crucible to melt. After that, the molten glass is stirred and homogenized, and then cast into a mold, slowly cooled to produce raw glass.

The obtained raw glass is annealed and the distortion remaining in the glass is removed. Cut and grind the produced amorphous glass base material, and perform face-to-face parallel grinding so that the thickness becomes 0.66mm. The base material of amorphous glass is colorless and transparent.

Chemical strengthening is performed on the amorphous glass base material that is ground in parallel to obtain an amorphous glass substrate. Specifically, in Comparative Example 1, after being immersed in a mixed molten salt of KNO ₃ and NaNO ₃ at a mixing ratio of KNO ₃ :NaNO ₃ =2:1 (weight ratio) at 450°C for 300 minutes, only KNO ₃ Soak in the molten salt at 450°C for 15 minutes. In Comparative Example 2, after being immersed in a mixed molten salt of KNO ₃ and NaNO ₃ at a mixing ratio of KNO ₃ :NaNO ₃ = 1:1 (weight ratio) at 450° C. for 500 minutes, in a molten salt containing only KNO ₃ Soak at 410°C for 15 minutes.

The following evaluations were performed on the obtained substrate. (1) Using the glass surface stress meter FSM-6000LE manufactured by Orihara Manufacturing Co., Ltd., the thickness of the compressive stress layer (stress depth DOLzero) of the amorphous glass substrate and the surface compressive stress value of the compressive stress layer from the outermost surface to DOLzero Perform the measurement. In Comparative Example 1, it was calculated with the refractive index of the sample 1.50 and the optical elastic constant 30.3 [(nm/cm)/MPa]. In Comparative Example 2, it was calculated with the refractive index of the sample 1.51 and the optical elastic constant 28.2 [(nm/cm)/MPa]. Obtain the surface compressive stress gradient A (MPa/μm) from the outermost surface to the depth of 6μm and the surface compressive stress gradient B (MPa/μm) from the depth (stress depth DOLzero-10μm) to the stress depth DOLzero . The central compressive stress (CT) is obtained by curve analysis. Furthermore, the thickness of the compressive stress layer (stress depth DOL) is also obtained by linear analysis. The results are shown in Table 1.

(2) The indentation hardness was measured in the same manner as in Examples 1 and 2. The results are shown in Table 1.

(3) The falling ball test was carried out in the same manner as in Examples 1 and 2. The results are shown in Table 2.

[Table 1] Example 1 Example 2 Comparative example 1 Comparative example 2 Material thickness [mm] 0.61 0.54 0.66 0.66 CS [MPa] 993.3 1027.8 841.5 828.7 CT [MPa] 43.9 55.4 67.9 33.0 DOLzero [μm] 54.0 41.5 75.7 62.3 The most surface to 6μm [ΔMPa] 567.3 453.7 225.8 486.8 Gradient A 94.6 75.6 37.6 81.1 DOLzero-10 to DOLzero [ΔMPa] 42.8 95.5 33.1 20.6 Gradient B 4.3 9.6 3.3 2.1 DOL by straight line analysis [μm] 64.0 57.3 84.0 90.4 Hardness indentation depth 20nm [GPa] 8.44 8.94 6.94 7.08 Hardness indentation depth 50nm [GPa] 8.75 8.72 7.45 7.13 Hardness indentation depth 100nm [GPa] 8.81 8.75 7.60 7.13 Hardness indentation depth 200nm [GPa] 8.94 8.83 8.03 7.50

[Table 2] Example 1 Example 2 Comparative example 1 Comparative example 2 Steel ball drop test result (mm) 10 〇 〇 〇 〇 20 〇 〇 〇 〇 30 〇 〇 〇 × 40 〇 〇 × 50 〇 〇 60 〇 〇 70 〇 〇 80 × × Fragmented state A A C A

Although a number of embodiments and/or embodiments of the present invention have been described in detail above, those with ordinary knowledge in the technical field will not deviate from the novel teachings and effects of the present invention in substance, and it is easy for those exemplified embodiments and / Or the embodiment imposes many changes. Therefore, these many changes are included in the scope of the present invention. The contents of the documents described in this specification are all quoted here.

no.

Fig. 1 is a diagram showing an example of the change in the compressive stress of the crystallized glass substrate of the present invention with respect to the depth from the outermost surface.

Claims (6)

A crystallized glass substrate with a compressive stress layer on the surface; When the depth when the surface compressive stress of the compressive stress layer is 0 MPa is the stress depth DOLzero, the gradient A of the surface compressive stress from the outermost surface to the depth of 6 μm in the compressive stress layer is 50.0 MPa/μm to 110.0 MPa/μm, the surface compressive stress gradient B from the stress depth DOLzero-10 μm to the stress depth DOLzero is 2.5 MPa/μm to 15.0 MPa/μm, and the hardness at the indentation depth of the outermost surface at 20 nm is 7.50 GPa To 9.50GPa. A crystallized glass substrate with a compressive stress layer on the surface; When the depth when the surface compressive stress of the compressive stress layer is 0 MPa is the stress depth DOLzero, the gradient A of the surface compressive stress from the outermost surface to the depth of 6 μm in the compressive stress layer is 50.0 MPa/μm to 110.0 MPa/μm, the surface compressive stress gradient B from the stress depth DOLzero-10 μm to the stress depth DOLzero is 2.5 MPa/μm to 15.0 MPa/μm, and the hardness at the indentation depth of the outermost surface at 100 nm is 8.00 GPa To 9.50GPa. A crystallized glass substrate with a compressive stress layer on the surface; When the depth when the surface compressive stress of the compressive stress layer is 0 MPa is the stress depth DOLzero, the gradient A of the surface compressive stress from the outermost surface to the depth of 6 μm in the compressive stress layer is 50.0 MPa/μm to 110.0 MPa/μm, the surface compressive stress gradient B from the depth of the aforementioned stress depth DOLzero-10μm to the aforementioned stress depth DOLzero is 2.5MPa/μm to 15.0MPa/μm; The surface compressive stress CS of the outermost surface of the compressive stress layer is 900.0 MPa to 1200.0 MPa. The crystallized glass substrate according to claim 1 or 2, wherein the aforementioned stress depth DOLzero is 30.0 μm to 70.0 μm; The surface compressive stress CS of the outermost surface of the aforementioned compressive stress layer is 870.0 MPa to 1150.0 MPa; The central compressive stress CT is 35.0MPa to 70.0MPa. The crystallized glass substrate as described in any one of claims 1 to 3, wherein when converted into weight% of oxide, it contains: SiO ₂ component 40.0% to 70.0%; Al ₂ O ₃ component 11.0% to 25.0%; Na ₂ O component 5.0% to 19.0%; K ₂ O component 0% to 9.0%; 1 or more selected from MgO component and ZnO component 1.0% to 18.0%; CaO component 0% to 3.0%; and TiO ₂ component 0.5 % To 12.0%. The crystallized glass substrate according to any one of claims 1 to 3, wherein the thickness of the crystallized glass substrate is 0.1 mm to 1.0 mm.

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