阅读说明：本技术 结晶化玻璃基板 (Crystallized glass substrate ) 是由 八木俊刚 小笠原康平 本岛勇纪 小岛玲香 山下丰 后藤直雪 于 2018-08-09 设计创作，主要内容包括：一种结晶化玻璃基板,其表面具有压缩应力层,所述压缩应力层的压缩应力为0MPa时的应力深度DOL_(zero)是45～200μm、所述压缩应力层的最外表面的压缩应力CS是400～1400MPa,所述最外表面的压缩应力CS与所述应力深度DOL_(zero)(μm)之积CS×DOL_(zero)是4.8×10~4以上。(A crystallized glass substrate having a compressive stress layer on the surface thereof, wherein the compressive stress layer has a stress depth DOL at a compressive stress of 0MPa zero Is 45 to 200 μm, the compressive stress CS of the outermost surface of the compressive stress layer is 400 to 1400MPa, the compressive stress CS of the outermost surface and the stress depth DOL zero Product CS x DOL of (mum) zero Is 4.8X 10 4 The above.)

1. A crystallized glass substrate having a compressive stress layer on a surface thereof,

the stress depth DOL when the compressive stress of the compressive stress layer is 0MPa_zero45 to 200 μm,

The compressive stress CS of the outermost surface of the compressive stress layer is 400 to 1400MPa,

compressive stress CS and said depth of stress DOL of said outermost surface_zeroProduct CS x DOL of (mum)_zeroIs 4.8X 10⁴The above.

2. The crystallized glass substrate according to claim 1, wherein the sum of the stress depths obtained from both surfaces of the crystallized glass substrate is 2 x DOL_zeroThe thickness is 10 to 80% of the thickness T of the crystallized glass substrate.

3. The crystallized glass substrate according to claim 1 or 2, which comprises, in% by weight in terms of oxides:

40.0 to 70.0 percent of SiO₂Ingredients (A) and (B),

11.0 to 25.0 percent of Al₂O₃Ingredients (A) and (B),

5.0 to 19.0 percent of Na₂O component (a),

0 to 9.0 percent of K₂O component (a),

1.0 to 18.0% of at least one component selected from the group consisting of MgO component and ZnO component,

0 to 3.0% of CaO component, and

0.5 to 12.0 percent of TiO₂And (3) components.

4. The crystallized glass substrate according to any one of claims 1 to 3, wherein a thickness T of the crystallized glass substrate is 0.1 to 1.0 mm.

5. A crystallized glass substrate according to any one of claims 1 to 4, wherein a ratio E/p of Young's modulus E (GPa) to specific gravity p is 31 or more.

6. The crystallized glass substrate according to any one of claims 1 to 5, wherein a sum of a compressive stress CS of the outermost surface and a central stress CT obtained by curve analysis is 600 to 1400 MPa.

7. The crystallized glass substrate according to any one of claims 1 to 6, wherein,

said depth of stress DOL_zeroIs 70 to 110 μm in diameter,

the compressive stress CS of the outermost surface is 550 to 890MPa,

the central stress CT is 100 to 250MPa,

the sum of the compressive stress CS of the outermost surface and the central stress CT is 800-1200 MPa.

8. The crystallized glass substrate according to any one of claims 1 to 6, wherein,

said depth of stress DOL_zeroIs 65 to 85 μm in diameter,

the compressive stress CS of the outermost surface is 700 to 860MPa,

the central stress CT is 120-240 MPa,

the thickness T of the crystallized glass substrate is 0.15 to 0.7 mm.

Technical Field

The present invention relates to a crystallized glass substrate having a compressive stress layer on a surface thereof.

Background

Portable electronic devices such as smart phones and tablet computers use cover glass to protect the display. In addition, in an optical device for an automobile, a lens is also protected by a protector. Further, in recent years, there is a demand for application to a case or the like as an exterior body of an electronic device. Also, in order for these devices to withstand more demanding uses, the need for materials that are hard and difficult to crack is increasing.

Conventionally, chemical strengthening has been known as a method for strengthening a glass substrate. For example, patent document 1 discloses a crystallized glass substrate for an information recording medium. When this crystallized glass substrate is subjected to chemical strengthening, a sufficient compressive stress value is not obtained.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2014-114200

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made in view of the above problems. The purpose of the present invention is to obtain a crystallized glass substrate which is hard and hard to break.

Means for solving the problems

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that a crystallized glass substrate having high impact resistance and being less likely to crack can be obtained by providing a predetermined compressive stress layer on the surface, and have completed the present invention. Specifically, the present invention provides the following products.

(mode 1)

A crystallized glass substrate having a compressive stress layer on a surface thereof,

the stress depth DOL when the compressive stress of the compressive stress layer is 0MPa_zero45 to 200 μm,

The compressive stress CS of the outermost surface of the compressive stress layer is 400 to 1400MPa,

compressive stress CS and said depth of stress DOL of said outermost surface_zeroProduct CS x DOL of (mum)_zeroIs 4.8X 10⁴The above.

(mode 2)

The crystallized glass substrate according to mode 1, wherein the total of the stress depths obtained from both surfaces of the crystallized glass substrate is 2 × DOL_zeroThe thickness is 10 to 80% of the thickness T of the crystallized glass substrate.

(mode 3)

The crystallized glass substrate according to mode 1 or 2, which comprises, in% by weight in terms of oxides:

40.0 to 70.0 percent of SiO₂Ingredients (A) and (B),

11.0 to 25.0 percent of Al₂O₃Ingredients (A) and (B),

5.0 to 19.0 percent of Na₂O component (a),

0 to 9.0 percent of K₂O component (a),

1.0 to 18.0% of at least one component selected from the group consisting of MgO component and ZnO component,

0 to 3.0% of CaO component, and

0.5 to 12.0 percent of TiO₂And (3) components.

(mode 4)

The crystallized glass substrate according to any one of modes 1 to 3, wherein a thickness T of the crystallized glass substrate is 0.1 to 1.0 mm.

(mode 5)

The crystallized glass substrate according to any one of aspects 1 to 4, wherein a ratio E/ρ of the Young's modulus E (GPa) to the specific gravity ρ is 31 or more.

(mode 6)

The crystallized glass substrate according to any one of modes 1 to 5, wherein a sum of the compressive stress CS of the outermost surface and the central stress CT obtained by curve analysis is 600 to 1400 MPa.

(mode 7)

The crystallized glass substrate according to any one of modes 1 to 6, wherein,

said depth of stress DOL_zeroIs 70 to 110 μm in diameter,

the compressive stress CS of the outermost surface is 550 to 890MPa,

the central stress CT is 100 to 250MPa,

the sum of the compressive stress CS of the outermost surface and the central stress CT is 800-1200 MPa.

(mode 8)

The crystallized glass substrate according to any one of modes 1 to 6, wherein,

said depth of stress DOL_zeroIs 65 to 85 μm in diameter,

the compressive stress CS of the outermost surface is 700 to 860MPa,

the central stress CT is 120-240 MPa,

the thickness T of the crystallized glass substrate is 0.15 to 0.7 mm.

According to the present invention, a crystallized glass substrate which is hard and hard to break can be obtained.

The crystallized glass substrate of the present invention can be used for cover glass for displays and lenses of electronic devices, outer frame members or housings, optical lens materials, and other various members.

Drawings

Fig. 1 is a schematic sectional view of a frame used in a drop test of an example.

Detailed Description

The present invention is not limited to the embodiments and examples described below, and can be carried out with appropriate modifications within the scope of the object of the present invention.

[ crystallized glass substrate ]

The crystallized glass substrate of the present invention is a crystallized glass substrate having a base material of crystallized glass (also referred to as a crystallized glass base material) and a compressive stress layer on a surface thereof. 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 to the inside, and the compressive stress is highest at the outermost surface and gradually decreases to zero toward the inside.

The compressive stress CS of the outermost surface of the compressive stress layer (also referred to as the outermost surface compressive stress) is 400 to 1400MPa, and may be 550 to 1300MPa, 600 to 1200MPa, 650 to 1000MPa, 700 to 890MPa, 700 to 880MPa, or 750 to 860MPa, for example.

Depth DOL at 0MPa of compressive stress layer_zero(also referred to as stress depth) of 45 to 200 μm, for example, 50 to 140 μm, 55 to 120 μm, 65 to 110 μm, 70 to 100 μm or 75 to 85 μm.

The sum of the stress depths determined from both surfaces of the crystallized glass substrate may be 10 to 80% of the thickness of the compressive stress layer, or 12 to 60%, 15 to 50%, or 20 to 40%.

The central stress CT may be 55 to 300MPa, for example, 60 to 250MPa, 65 to 240MPa, 80 to 230MPa, 100 to 200MPa, 105 to 180MPa or 120 to 150 MPa. In the present invention, the central stress CT is obtained by curve analysis.

The sum of the compressive stress CS of the outermost surface and the central stress CT may be 600 to 1400MPa, or 700 to 1200MPa, 750 to 1100MPa, or 800 to 1000 MPa.

The crystallized glass substrate of the present invention has a compressive stress at the outermost surface denoted as CS (MPa) and a stress depth denoted as DOL_zeroIn (. mu.m), CS. times.DOL_zeroIs 4.8X 10⁴The above. For example, it may be 4.8 × 10⁴～9.0×10⁴、5.0×10⁴～8.0×10⁴、5.3×10⁴～7.2×10⁴、5.5×10⁴～7.0×10⁴Or 5.7X 10⁴～6.9×10⁴。

Compressive stress layer having the above-mentioned depth of stress DOL_zeroThe outermost surface should be compressedThe force CS and the central stress CT, particularly if they have the above-mentioned stress depth and the outermost surface compressive stress, make the substrate difficult to damage. The stress depth, the outermost surface compressive stress and the central stress 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 0.15mm or more, more preferably 0.30mm or more, still more preferably 0.40mm or more, and still more preferably 0.50mm or more, and the upper limit of the thickness of the crystallized glass substrate is preferably 1.00mm or less, more preferably 0.90mm or less, still more preferably 0.70mm or less, and still more preferably 0.6mm or less.

The ratio E/rho of Young's modulus E (GPa) to specific gravity rho of the crystallized glass substrate is preferably not less than 31, more preferably not less than 32, and still more preferably not less than 33.

Crystallized glass is a material having a crystalline phase and a glass phase, and is distinguished from amorphous solids. Generally, the crystalline phase of the crystallized glass is discriminated by using a peak angle appearing in an X-ray diffraction pattern of an X-ray diffraction analysis and TEMEDX as necessary.

The crystallized glass may contain, for example, MgAl as a crystal phase₂O₄、MgTi₂O₄、MgTi₂O₅、Mg₂TiO₄、Mg₂SiO₄、MgAl₂Si₂O₈、Mg₂Al₄Si₅O₁₈、Mg₂TiO₅、MgSiO₃、NaAlSiO₄、FeAl₂O₄And a solid solution thereof.

The average grain size of the crystallized glass is, for example, 4 to 15nm, and may be 5 to 13nm or 6 to 10 nm. When the average crystal grain diameter is small, the surface roughness Ra after polishing can be easily processed smoothly into a numberDegree of the disease. Further, the transmittance may become high.

The compositional ranges of the respective components constituting the crystallized glass are as follows. In the present specification, the content of each component is expressed in terms of weight% in terms of oxide unless otherwise specified. Here, "oxide conversion" means that, assuming that all the components of the crystallized glass are decomposed and converted to oxides, the amount of the oxide of each component contained in the crystallized glass is expressed as wt% when the total weight of the oxides is taken as 100 wt%.

The crystallized glass as a base material preferably contains, in terms of oxide, in% by weight:

40.0 to 70.0 percent of SiO₂Ingredients (A) and (B),

11.0 to 25.0 percent of Al₂O₃Ingredients (A) and (B),

5.0 to 19.0 percent of Na₂O component (a),

0 to 9.0 percent of K₂O component (a),

1.0 to 18.0% of at least one component selected from the group consisting of MgO component and ZnO component,

0 to 3.0 percent of CaO component,

0.5 to 12.0 percent of TiO₂And (3) components.

SiO₂The component (B) is more preferably 45.0 to 65.0%, still more preferably 50.0 to 60.0%.

Al₂O₃The component (B) is more preferably 13.0 to 23.0%.

Na₂The content of the component O is more preferably 8.0% to 16.0%, and may be 9.0% or more or 10.5% or more.

K₂The content of the component O is more preferably 0.1% to 7.0%, still more preferably 1.0% to 5.0%.

More preferably, the content of 1 or more components selected from the MgO component and the ZnO component is 2.0 to 15.0%, still more preferably 3.0 to 13.0%, and particularly preferably 5.0 to 11.0%. The 1 or more components selected from the MgO component and the ZnO component may be only the MgO component, only the ZnO component, or both, but preferably only the MgO component.

The CaO component is more preferably contained in an amount of 0.01 to 3.0%, still more preferably 0.1 to 2.0%.

TiO₂The component (B) is more preferably contained in an amount of 1.0 to 10.0%, still more preferably 2.0 to 8.0%.

The crystallized glass may contain 0.01 to 3.0% (preferably 0.1 to 2.0%, more preferably 0.1 to 1.0%) of Sb₂O₃Composition, SnO₂Component (B) and CeO₂More than 1 component of the component (A).

The above-described amounts of blending can be appropriately combined.

Selected from SiO₂Component (C) and Al₂O₃Component (I) Na₂More than 1 of O component, MgO component, ZnO component, and TiO₂The total amount of the components may be 90% or more, preferably 95% or more, more preferably 98% or more, and still more preferably 98.5% or more.

Selected from SiO₂Component (C) and Al₂O₃Component (I) Na₂Component O and K₂More than 1 of O component, MgO component and ZnO component, CaO component and TiO component₂Component (A), and with Sb₂O₃Composition, SnO₂Component (B) and CeO₂The total amount of 1 or more components of the component(s) may be 90% or more, preferably 95% or more, more preferably 98% or more, and still more preferably 99% or more. These components may also be present at 100%.

The crystallized glass may or may not contain ZrO within a range not impairing the effects of the present invention₂And (3) components. The amount of the additive can be 0-5.0%, 0-3.0% or 0-2.0%.

In addition, the crystallized glass may or may not contain B, respectively, within a range not impairing the effects of the present invention₂O₃Component (B) P₂O₅Component (B), BaO component, FeO component, SnO₂Component (C), Li₂O component, SrO component, La₂O₃Component (B) and (Y)₂O₃Component (B) and Nb₂O₅Component (A) Ta₂O₅Component (I) and WO₃Component (C) TeO₂Component (B) Bi₂O₃And (3) components. The blending amount of each of the above-mentioned additives may be 0 to 20%, 0 or more and less than 2.0%, or 0 to 1.0%.

The crystallized glass of the present invention, as a fining agent, has Sb as an exception₂O₃Composition, SnO₂Component (C) CeO₂In addition to the components, may or may not contain As₂O₃Component (b) and (c) is selected from F, Cl, NO_X、SO_XOne or more than two of the formed groups. The upper limit of the content of the clarifying agent is preferably 5.0% or less, more preferably 2.0% or less, and most preferably 1.0% or less.

The crystallized glass as a base material preferably contains, in terms of mol% in terms of oxides:

43.0 mol% -73.0 mol% SiO₂Ingredients (A) and (B),

4.0 mol% -18.0 mol% of Al₂O₃Ingredients (A) and (B),

5.0 mol% -19.0 mol% of Na₂O component (a),

0 mol% to 9.0 mol% of K₂O component (a),

2.0 to 22.0 mol% of at least one component selected from the group consisting of MgO component and ZnO component,

0 to 3.0 mol% of CaO component,

0.5 mol% -11.0 mol% of TiO₂And (3) components.

Selected from SiO₂Component (C) and Al₂O₃Component (I) Na₂More than 1 of O component, MgO component and ZnO component, and TiO₂The total content of the components may be 90 mol% or more, preferably 95 mol% or more, more preferably 98 mol% or more, and still more preferably 99 mol% or more.

Other components not mentioned above may be added to the crystallized glass of the present invention as necessary within a range not impairing the characteristics of the crystallized glass of the present invention. For example, the crystallized glass (and the substrate) of the present invention may be colorless and transparent, but the glass may be colored within a range not impairing the characteristics of the crystallized glass.

Further, since each component of Pb, Th, Tl, Os, Be, and Se is considered to Be a harmful chemical substance in recent years and tends to Be avoided, it is preferable that these components are not substantially contained.

The crystallized glass substrate of the present invention is preferably 60cm or more, 70cm or more, 80cm or more, 90cm or more, 100cm or more, or 110cm or more in the height at which breakage occurs in the drop test measured in examples.

[ production method ]

The crystallized glass of the present invention can be produced by the following method. That is, the raw materials are uniformly mixed and melt-formed to produce a starting glass. Then, the starting glass is crystallized to produce a crystallized glass base material. Further, the crystallized glass base material is chemically strengthened.

The starting glass is heat-treated to precipitate crystals in the glass. The heat treatment may be performed at a temperature of 1 stage or 2 stages.

In the 2-stage heat treatment, the 1 st temperature is first subjected to heat treatment to thereby perform a nucleation step, and after the nucleation step, the 2 nd temperature higher than the nucleation step is further subjected to heat treatment to thereby perform a crystal growth step.

In the 1-stage heat treatment, the nucleation step and the crystal growth step are continuously performed at a temperature of 1 stage. Generally, 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 1 st temperature of the 2-stage heat treatment is preferably 600 to 750 ℃. The holding time at the 1 st temperature is preferably 30 minutes to 2000 minutes, more preferably 180 minutes to 1440 minutes.

The 2 nd temperature of the 2-stage heat treatment is preferably 650 to 850 ℃. The holding time at the 2 nd temperature is preferably 30 minutes to 600 minutes, more preferably 60 minutes to 300 minutes.

When the heat treatment is performed at a 1-stage temperature, the heat treatment temperature is preferably 600 to 800 ℃, more preferably 630 to 770 ℃. The holding time at the heat treatment temperature is preferably 30 minutes to 500 minutes, more preferably 60 minutes to 300 minutes.

A thin plate-like crystallized glass base material can be produced from the crystallized glass base material by using a method such as grinding and polishing.

Thereafter, a compressive stress layer can be formed in the crystallized glass base material by ion exchange in the chemical strengthening method.

The crystallized glass substrate of the present invention can be formed not by a mixed molten salt (mixed salt bath) of a potassium salt and a sodium salt but by a potassium salt (1 or 2 or more kinds of potassium salts, for example, potassium nitrate (KNO)₃) Potassium carbonate (K)₂CO₃) Potassium sulfate (K)₂SO₄) A molten salt (single salt bath) is subjected to a chemical strengthening treatment at a predetermined temperature for a predetermined time, thereby obtaining a crystallized base material. For example, in a molten salt heated to 450 ℃ to 580 ℃ (500 ℃ to 550 ℃, or 520 ℃ to 530 ℃), for example, 380 minutes to 630 minutes, 400 minutes to 600 minutes, 450 minutes to 550 minutes, or 480 minutes to 520 minutes. By such chemical strengthening, the components present in the vicinity of the surface and the components contained in the molten salt undergo an ion exchange reaction, and as a result, a compressive stress layer having the above characteristics is formed in the surface portion. In particular, when the substrate is strengthened at 500 to 550 ℃ for 480 to 520 minutes, a substrate which is difficult to crack can be easily obtained.

Examples

Examples 1 to 11 and comparative example 1

In examples 1 to 11, as the raw materials of each component of the crystallized glass, the corresponding raw materials such as oxide, hydroxide, carbonate, nitrate, fluoride, chloride, metaphosphoric acid compound were selected, and these raw materials were weighed and uniformly mixed in the following composition ratios.

(weight% in terms of oxide)

SiO₂54% of Al₂O₃The component is 18 percent and Na₂The O component is 12%, K₂2% of O component, 8% of MgO component, 1% of CaO component, and TiO component₂5% of Sb₂O₃The content of the components is 0.1 percent.

Next, the mixed raw materials were put into a platinum crucible to be melted. Then, the molten glass is homogenized by stirring, and then cast in a mold and gradually cooled to produce a starting glass.

The obtained starting glass was subjected to 1-stage heat treatment (650 to 730 ℃ C., 5 hours) for nucleation and crystallization to prepare crystallized glass as a base material. The crystallized glass obtained was analyzed by a 200kV field emission transmission electron microscope FE-TEM (JEM 2100F, manufactured by JE), and as a result, precipitated crystals having an average crystal grain diameter of 6 to 9nm were observed. Further, the lattice image of the electron diffraction pattern was confirmed, and EDX analysis was performed to confirm MgAl₂O₄、MgTi₂O₄The crystalline phase of (1). Average grain size was determined by transmission electron microscopy at 180X 180nm²The crystal grain diameter of the crystal grains in the range of (1), and the average value of the crystal grain diameters is calculated.

The crystallized glass base material thus obtained was cut and ground to obtain a shape having a length of 150mm, a width of 70mm and a thickness of more than 1.0mm, and the surface thereof was polished in parallel. The crystallized glass base material was colorless and transparent.

The crystallized glass base material polished in parallel in the opposite direction to a thickness shown in table 1 was chemically strengthened to obtain a crystallized glass substrate having a compressive stress layer on the surface. Specifically, the salt bath temperature and the immersion time were measured in KNO according to the Table 1₃Is immersed in the molten salt of (3).

In comparative example 1, a general chemically strengthened glass substrate having the following composition was used. The substrate is immersed in KNO₃With NaNO₃After the mixed salt bath, the mixture was immersed in KNO₃A single salt bath.

(weight% in terms of oxide)

SiO₂54% of Al₂O₃13% of Na as the component₂O component 5%, K₂17% of O component, 5.5% of MgO component, 0.5% of CaO component, and B₂O₃ZrO content of 3% by weight₂The component is 2 percent.

The compressive stress value (CS) (MPa) and the depth of stress (DOL) of the outermost surface of the crystallized glass substrate were measured by using a glass surface stress meter FSM-6000 LE manufactured by flexography_zero) (μm). The refractive index of the sample was 1.54, and the optical elastic constant was 29.658[ (nm/cm)/MPa]To calculate. The central stress value (CT) (MPa) was obtained by Curve analysis (Curve analysis). Table 1 also describes: thickness (T) (mm) of the substrate; CS × DOL_zeroDOL in thickness (T) of substrate_zero(DOL obtained from both sides of the substrate)_zeroSum of (d) of (2 DOL)_zero/1000T × 100); the sum of the outermost surface compressive stress value and the central stress value (CS + CT) (MPa).

The steel ball drop test was performed on the crystallized glass substrate in the following manner.

An acrylic manufactured frame 1 having a cross-section as shown in fig. 1 was used. The frame 1 is formed by a rectangular outer frame 10 and an inner frame 20 lower than the outer frame, and steps are formed by the outer frame and the inner frame, and the inner side of the inner frame is empty. The inner dimensions of the outer frame 10 are 151mm × 71mm, and the inner frame 20 is 141mm × 61 mm. The crystallized glass substrate 30 is placed inside the outer frame and on the inner frame. 130g of a stainless steel ball was dropped from a height of 10cm from the crystallized glass substrate. After dropping, if the substrate is not damaged, the height is raised by another 10cm, and the same test is continued until the substrate is damaged. The height of the damage to the substrate is shown in table 1. As can be seen from table 1, the substrates of the examples were hardly damaged.

Further, Young's modulus E (GPa) and specific gravity ρ are measured, and the ratio E/ρ is determined. Young's modulus was measured by an ultrasonic method. The results are shown in Table 1.

[ TABLE 1 ]

Although the embodiments and/or examples of the present invention have been described in detail, those skilled in the art can easily make various changes to the embodiments and/or examples of the example embodiments without substantially departing from the novel teaching and effects of the present invention. Therefore, these various modifications are also included in the scope of the present invention.

The entire contents of the documents described in this specification are incorporated herein by reference.