WO2024062797A1

WO2024062797A1 - Crystallised glass

Info

Publication number: WO2024062797A1
Application number: PCT/JP2023/029313
Authority: WO
Inventors: 早矢吉川; 俊剛八木
Original assignee: 株式会社オハラ
Priority date: 2022-09-22
Filing date: 2023-08-10
Publication date: 2024-03-28
Also published as: TW202413297A; JP2024045871A

Abstract

A crystallised glass containing α-cristobalite and lithium disilicate as main crystal phases and containing, in mass%, 65.0%-85.0% of a SiO2 component, 1.5%-5.9% of an Al2O3 component, more than 0% and 5.0% or less of a P2O5 component, 5.0%-10.8% of a Li2O component, and 4.0%-12.5% of a ZrO2 component in terms of oxide, wherein [(the content of the SiO2 component + the content of the Li2O component)/the content of the Al2O3 component] is more than 13.9.

Description

crystallized glass

The present invention relates to crystallized glass, particularly hard crystallized glass.

In recent years, glass materials have begun to be used for the cover glass and housing of smartphones to increase the degree of design freedom. These glass members are required to be resistant to scratches and resistant to breakage even when subjected to impact from external factors, such as when a smartphone is dropped on asphalt.

Crystallized glass is a type of glass with increased strength and hardness. Crystallized glass is made by depositing crystals inside glass, and is known to have better mechanical strength than amorphous glass. Furthermore, it is also known to increase strength and hardness by forming a compressive stress layer on the surface by chemical strengthening or the like.

Patent Document 1 discloses a glass-ceramic material having a transparent or translucent petalite crystalline phase and a lithium silicate crystalline phase, which has rapid ion exchangeability and high fracture toughness.

Patent Document 2 discloses a reinforced crystallized glass containing α-cristobalite.

JP 2021-095333 Publication JP2022-044054A

However, for applications such as smartphone glass components, there was a demand for glass with even higher hardness.

An object of the present invention is to provide a hard crystallized glass.

As a result of intensive research, the inventors have discovered that by heat treating glass having a specified composition under specified conditions, crystallized glass containing both α-cristobalite and lithium disilicate as the main crystal phase can be obtained, and that the addition of lithium disilicate to α-cristobalite increases hardness. They also discovered that while crystallized glass containing lithium disilicate as the main crystal phase is difficult to two-stage chemically strengthen, glass with a specified composition and main crystal phase is easy to two-stage chemically strengthen. These findings led to the completion of the present invention.

The present invention provides the following.
(Configuration 1)
Contains α-cristobalite and lithium disilicate as the main crystal phase,
In terms of oxide mass%,
Content of _two SiO components: 65.0% to 85.0%,
Content of _three Al ₂ O components: 1.5% to 5.9%,
Content of P ₂ O ₅ components: more than 0% and less than 5.0%,
Content of Li ₂ O component 5.0% to 10.8%,
Content of _two ZrO components: 4.0% to 12.5%,
and
[(Content of ₂ SiO components + Content of Li ₂ O component)/Content of ₃ Al ₂ O components] More than 13.9,
A crystallized glass characterized by:
(Configuration 2)
In terms of oxide mass%,
Content of _three B ₂ O components: 0% to 5.0%,
Content of Na ₂ O component 0% to 5.0%,
K ₂ O component content 0% to 5.0%,
MgO component content 0% to 5.0%,
Content of CaO component: 0% to 5.0%,
Content of ZnO component: 0% to 5.0%,
Content of _two TiO components: 0% to 5.0%,
Content of Gd ₂ O ₃ components 0% to 5.0%,
Content of _three Sb ₂ O components: 0% to 3.0%,
Content of Nb ₂ O ₅ components 0% to 3.0%,
The crystallized glass according to configuration 1, characterized in that:
(Configuration 3)
The crystallized glass according to configuration 1 or 2, wherein the content of the _two ZrO components is 4.7% to 12.5%.
(Configuration 4)
The crystallized glass according to any one of Structures 1 to 3, wherein the content of the _two ZrO components is more than 7% and 12.5% or less.
(Configuration 5)
In terms of oxide mass%,
[(Content of K ₂ O component + content of ₃ components of Al ₂ O) / content of ₂ components of ZrO] less than 0.88,
The crystallized glass according to any one of Structures 1 to 4, characterized in that:
(Configuration 6)
In terms of oxide mass%,
[(Content of P ₂ O ₅ components + content of K ₂ O component + content of MgO component + content of ₃ Al ₂ O components) / content of ₂ ZrO components] less than 1.32,
The crystallized glass according to any one of Structures 1 to 5, characterized in that:
(Configuration 7)
The crystallized glass according to any one of Structures 1 to 6, which has a compressive stress layer on its surface.
(Configuration 8)
The crystallized glass according to any one of Structures 1 to 7, which is used for a glass member of a smartphone.

According to the present invention, hard crystallized glass can be provided.

In view of its high hardness, the crystallized glass of the present invention can be used as a component for smartphone housings, portable electronic devices such as tablet PCs and wearable devices, and for protection used in transportation vehicles such as cars and airplanes. It can be used as a member for protectors, heads-up display boards, etc.

The following provides a detailed explanation of embodiments and examples of the crystallized glass of the present invention, but the present invention is in no way limited to the following embodiments and examples, and can be practiced with appropriate modifications within the scope of the object of the present invention.

In this specification, unless otherwise specified, the content of each component is expressed in mass % in terms of oxide. Here, "in terms of oxide" refers to the amount of water contained in crystallized glass when the total mass of the oxides is 100% by mass, assuming that all the constituent components of crystallized glass are decomposed and converted to oxides. The amount of oxide of each component contained is expressed in mass %. In this specification, A% to B% represents A% or more and B% or less.

The crystallized glass of the present invention contains α-cristobalite and lithium disilicate as main crystal phases. By including both of these crystal phases in a predetermined composition, the present invention has higher hardness than a crystallized glass that contains α-cristobalite but not lithium disilicate. Crystalline phases also include solid solutions.
In the present invention, the "main crystalline phase" refers to the crystalline phase that is contained the most among the main crystalline phases identified from the peak of the X-ray diffraction pattern of crystallized glass, that is, the crystalline phase that is contained the first and second most. It is a crystalline phase. α-cristobalite may be the first predominant crystalline phase, and lithium disilicate may be the first predominant crystalline phase.
The crystallized glass may further contain one or more other crystal phases selected from petalite, vergilite, quartz, and lithium monosilicate crystals, but it is preferable that these crystal phases are present in small amounts or not included. .

Crystallized glass containing α-cristobalite and lithium disilicate as main crystal phases can be obtained by crystallizing raw glass having the following composition by heat treatment.
The composition of crystallized glass is expressed as oxide mass%,
The content of _two SiO components is 65.0% to 85.0%,
The content of the _three Al ₂ O components is 1.5% to 5.9%,
The content of P ₂ O ₅ components is more than 0% and not more than 5.0%,
The content of Li ₂ O component is 5.0% to 10.8%,
The content of ZrO ₂ components is 4.0% to 12.5%,
[(Content of ₂ SiO components + Content of Li ₂ O components)/Content of ₃ Al ₂ O components] is more than 13.9.

In particular, by setting the contents of the SiO ₂ component, Al ₂ O ₃ component, and Li ₂ O component within the above ranges, a predetermined crystal phase can be obtained. If the Al ₂ O ₃ component is more than the above upper limit, a lithium aluminum silicate crystal phase is likely to be generated, and if the SiO ₂ component and Li ₂ O component are outside the above range, lithium disilicate is not formed and only α-cristobalite is generated. It becomes easier.

The SiO ₂ component is a skeleton component constituting crystallized glass, and is an essential component necessary for increasing stability and precipitating a desired crystal phase. Setting the content of the _two SiO components to 85.0% or less can suppress excessive increases in viscosity and deterioration of solubility, and setting the content to 65.0% or more can improve the stability of crystallized glass. can be improved.
Therefore, the upper limit is preferably 85.0% or less, more preferably 83.0% or less, even more preferably 80.0% or less. Further, the lower limit is preferably 65.0% or more, more preferably 68.0% or more, and even more preferably more than 70.0%.

The _three Al ₂ O components are skeleton components constituting crystallized glass, and are essential components necessary to improve stability. When the content of the Al ₂ O ₃ components is 5.9% or less, the transmittance at 450 nm can be increased and deterioration of devitrification can be suppressed, and when the content is 1.5% or more, the stability It can suppress sexual deterioration.
Therefore, the upper limit is preferably 5.9% or less, more preferably 5.5% or less, even more preferably 5.3% or less. Further, the lower limit is preferably 1.5% or more, more preferably 1.8% or more, and even more preferably 2.0% or more.

The P ₂ O ₅ component is an essential component that promotes crystal formation of crystallized glass. When the content of the P ₂ O ₅ component is 5.0% or less, phase separation of the glass can be suppressed. Moreover, if it is 0%, the desired crystal phase cannot be obtained.
Therefore, the upper limit is preferably 5.0% or less, more preferably 4.5% or less, even more preferably 4.0% or less. Further, the lower limit is preferably more than 0%, more preferably 0.5% or more, and even more preferably 1.0% or more.

The Li ₂ O component is an essential component necessary for improving the meltability of the raw glass, increasing the manufacturability, and precipitating a desired crystal phase. When the content of the Li ₂ O component is 10.8% or less, deterioration of devitrification can be suppressed, and when it is 5.0% or more, deterioration of viscosity and meltability can be suppressed, Manufacturability can be improved. Moreover, a desired crystal phase can be obtained.
Therefore, the upper limit is preferably 10.8% or less, more preferably 10.5% or less, for example, 10.2% or less, 8.9% or less, or 8.5% or less. Further, the lower limit is preferably 5.0% or more, more preferably 6.2% or more, even more preferably 7.0% or more, and can be, for example, 8.1% or more, or 9.0% or more.

The ZrO ₂ component is a component that serves as a crystal nucleating agent. When the content of _{the two} ZrO components is 12.5% or less, deterioration in solubility can be suppressed. When the content of the _two ZrO components is 4.0% or more, it becomes easy to increase the transmittance at 450 nm.
Therefore, the upper limit is preferably 12.5% or less, for example, 12.0% or less, 11.5% or less, 11.0% or less, 10.0% or less, or 9.0% or less. Also, preferably the lower limit is 4.0% or more, more preferably 4.7% or more, more preferably 5.7% or more, still more preferably more than 6.9%, for example, more than 7%, or 10%. It can be 5% or more.

Although the glass according to the present invention can be produced even when the MgO component is 0%, it is an optional component that improves low-temperature meltability when it is contained in an amount exceeding 0%. In the present invention, optional components are components that may or may not be included. When the content of the MgO component is 5.0% or less, chemical strengthening becomes easier.
Therefore, the upper limit is preferably 5.0% or less, more preferably 3.0% or less, and still more preferably less than 2.0%. Further, the lower limit is preferably set to 0% or more, more preferably 0.1% or more, and still more preferably 0.2% or more.

The ZnO component is an optional component that improves low-temperature meltability when contained in an amount exceeding 0%, although it is possible to produce the glass according to the present invention even when the ZnO component is 0%. When the content of the ZnO component is 5.0% or less, chemical strengthening becomes easier.
Therefore, the upper limit is preferably 5.0% or less, more preferably 3.0% or less, and still more preferably less than 2.0%. Further, the lower limit is preferably 0% or more, more preferably more than 0%, more preferably 0.1% or more, and still more preferably 0.2% or more.

Although the glass according to the present invention can be produced even when the CaO component is 0%, it is an optional component that improves low-temperature meltability when it is contained in an amount exceeding 0%. When the content of the CaO component is 5.0% or less, chemical strengthening becomes easier.
Therefore, the upper limit is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably less than 1.0%. Further, the lower limit is preferably more than 0%, more preferably 0.1% or more, more preferably 0.2% or more, and still more preferably 0.3% or more.

The K ₂ O component and the Na ₂ O component are optional components that improve the meltability of the raw glass and increase the productivity. When the content of each of the K ₂ O component and the Na ₂ O component is 5.0% or less, deterioration of devitrification can be suppressed. Further, the glass according to the present invention can be produced even when the K ₂ O component and Na ₂ O component are 0%, but when they are contained in excess of 0%, deterioration of viscosity and meltability are suppressed, and productivity is improved. can be increased.
Therefore, the upper limit of the Na ₂ O component is preferably 5.0% or less, more preferably 4.0% or less, more preferably less than 3.0%, and still more preferably less than 2.0%. Further, the lower limit is preferably 0% or more, more preferably 0.2% or more, and even more preferably 0.3% or more.
The upper limit of the K ₂ O component is preferably 5.0% or less, more preferably 4.0% or less, and can be, for example, 3.0% or less, 2.0% or less, or 1.0% or less. Also, preferably the lower limit is 0% or more, more preferably 0.2% or more, even more preferably 0.3% or more, for example, 0.5% or more, 1.0% or more, 2.0% or more, It can be 2.5% or more, or 3.0% or more.

The Sb ₂ O ₃ component is an optional component that functions as a clarifying agent when producing raw glass. If the Sb ₂ O ₃ component is contained excessively, the transmittance in the short wavelength region of the visible light region may deteriorate. Therefore, the upper limit is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, more preferably 0.6% or less, even more preferably 0.5% or less. Preferably, the lower limit is 0% or more, more preferably 0.01% or more, and even more preferably 0.03 or more.

The B ₂ O ₃ component is an optional component that has the effect of lowering the viscosity of the raw glass. When the content of the _three B ₂ O components is 5.0% or less, deterioration of devitrification can be suppressed. Further, the glass according to the present invention can be produced even when the content of _{the three} B ₂ O components is 0%, but when the content exceeds 0%, deterioration of the viscosity and meltability of the original glass can be suppressed. .
Therefore, the upper limit is preferably 5.0% or less, more preferably 4.5% or less, even more preferably 4.0% or less. Further, the lower limit is preferably 0% or more, more preferably more than 0%, more preferably 0.1% or more, and still more preferably 0.3% or more.

The _TiO2 component is an optional component that has the effect of increasing the refractive index. When the content of the _two TiO components is 5.0% or less, deterioration of devitrification can be suppressed. Further, although the glass according to the present invention can be produced even when the content of the TiO ₂ component is 0%, the refractive index can be increased when the content exceeds 0%.
Therefore, the upper limit is preferably 5.0% or less, more preferably 4.5% or less, and even more preferably 4.0% or less. Further, the lower limit is preferably 0% or more, more preferably more than 0%, more preferably 0.1% or more, and still more preferably 0.3% or more.

The Gd ₂ O ₃ component is an optional component that has the effect of increasing the refractive index. When the content of the _three Gd ₂ O components is 5.0% or less, deterioration of devitrification can be suppressed. Although the glass according to the present invention can be produced even when the content of the Gd ₂ O ₃ component is 0%, the refractive index can be increased when the content exceeds 0%.
Therefore, the upper limit is preferably 5.0% or less, more preferably 4.5% or less, and even more preferably 4.0% or less. Further, the lower limit is preferably 0% or more, more preferably more than 0%, more preferably 0.1% or more, and still more preferably 0.3% or more.

The Nb ₂ O ₅ component is an optional component that has the effect of increasing the refractive index. When the content of the Nb ₂ O ₅ component is 3.0% or less, deterioration of devitrification can be suppressed. Further, the glass according to the present invention can be produced even when the content of the Nb ₂ O ₅ component is 0%, but when the content exceeds 0%, the refractive index can be increased.
Therefore, the upper limit is preferably 3.0% or less, more preferably 2.0% or less, and even more preferably 1.0% or less. Further, the lower limit is preferably 0% or more, more preferably more than 0%, more preferably 0.1% or more, and still more preferably 0.3% or more.

Although the glass according to the present invention can be produced even with 0% of the SrO component and the BaO component, these are optional components that improve low-temperature melting property when contained in excess of 0%. When the content of each of the SrO component and the BaO component is 5.0% or less, the glass is easily strengthened when chemically strengthened.
Therefore, the upper limit of each of the SrO component and the BaO component can be preferably set to 5.0% or less, more preferably 3.0% or less, and further preferably 1.0% or less.

By setting the total content of CaO component and MgO component [content of CaO component + content of MgO component] to 5.0% or less, it is possible to prevent chemical strengthening from becoming difficult, and even at 0%, the glass according to the present invention can be made. However, if the content exceeds 0%, deterioration of meltability can be suppressed.
Therefore, the preferable upper limit of [content of CaO component + content of MgO component] is 5.0% or less, more preferably 3.0% or less, more preferably less than 3.0%, and still more preferably 1.0% or less. .
Further, the preferable lower limit of [content of CaO component+content of MgO component] is 0% or more, more preferably 0.1% or more, and still more preferably 0.2% or more.

The glass according to the present invention can be produced even if the total content of the K ₂ O component and the Na ₂ O component [content of the K ₂ O component + content of the Na ₂ O component] is 0%; In some cases, deterioration of viscosity can be suppressed and an increase in melting temperature can be suppressed. Further, by setting the content to 5.0% or less, deterioration of devitrification can be suppressed.
Therefore, [content of K ₂ O component + content of Na ₂ O component] preferably has an upper limit of 5.0% or less, more preferably 4.0% or less, more preferably less than 4.0%, and more preferably 3 It should be less than .0%, more preferably less than 2.0%. Further, the lower limit is preferably 0% or more, more preferably 0.2% or more, and still more preferably 0.3% or more.

By setting [(content of SiO ₂ components + content of Li ₂ O components)/content of Al ₂ O ₃ components] to more than 13.9, α-cristobalite and lithium disilicate can be produced as the main crystal phases.
Therefore, the preferable upper limit of [(content of SiO ₂ components + content of Li ₂ O components)/content of Al ₂ O ₃ components] is 50.0 or less, more preferably 48.0 or less, still more preferably 45.0 or less. do. Further, the preferable lower limit is more than 13.9, more preferably 14.5 or more, and still more preferably 15.0 or more.

[(Content of K ₂ O component + content of ₃ Al ₂ O components)/content of ₂ ZrO components] may be less than 0.88. By setting it to less than 0.88, α-cristobalite and lithium disilicate can be easily produced as the main crystal phases.
Therefore, the preferable upper limit of [(content of K ₂ O component + content of ₃ components of Al ₂ O)/content of ₂ components of ZrO] is less than 0.88, more preferably 0.87 or less, still more preferably 0.85 or less. do. Further, the lower limit is preferably 0.10 or more, more preferably 0.15 or more, and still more preferably 0.20 or more.

[(Content of P ₂ O ₅ components + content of K ₂ O component + content of MgO component + content of ₃ Al ₂ O components)/content of ₂ ZrO components] may be less than 1.32. By setting it to less than 1.32, α-cristobalite and lithium disilicate can be easily produced as the main crystal phases.
Therefore, the preferable upper limit of [(content of P ₂ O ₅ components + content of K ₂ O component + content of MgO component + content of ₃ Al ₂ O components)/content of ₂ ZrO components] is less than 1.32, more preferably 1. 28 or less, more preferably 1.25 or less. Further, the lower limit is preferably 0.2 or more, more preferably 0.3 or more, and still more preferably 0.4 or more.

[Content of ₃ Al ₂ O components/content of ₂ ZrO components] may be greater than 0 and less than or equal to 1.0. By setting it to 1.0 or less, it becomes easier to obtain a desired crystal phase, and by setting it to more than 0, it becomes easier to suppress deterioration of devitrification.
Therefore, the preferable upper limit of [content of ₃ Al ₂ O components/content of ₂ ZrO components] is 1.0 or less, more preferably 0.9 or less, still more preferably 0.8 or less. Further, the preferable lower limit is more than 0, more preferably 0.1 or more, and still more preferably 0.2 or more.

[Li ₂ O component content + Al ₂ O ₃ component content] may be 6.5% to 15.5%. When the content is 15.5% or less, the formation of a lithium aluminum silicate crystal phase can be easily suppressed, and when the content is 6.5% or more, a desired crystal phase can be obtained and the glass can be easily stabilized.
Therefore, the preferable upper limit of [content of Li ₂ O component + content of _three Al ₂ O components] is 15.5% or less, more preferably 15.0% or less, and more preferably 14.0% or less. Further, the preferable lower limit is 6.5% or more, more preferably 8.0% or more, and still more preferably 10.0% or more.

[(Li ₂ O component content + Al ₂ O ₃ component content)/ZrO ₂ component content] may be set to 1.0 to 2.7. By setting it to 2.7 or less, it becomes easier to suppress the formation of a lithium aluminum silicate crystal phase, and by setting it to 1.0 or more, it becomes easier to stabilize the glass while obtaining a desired crystal phase.
Therefore, the preferable upper limit of [(content of Li ₂ O component + content of ₃ Al ₂ O components)/content of ₂ ZrO components] is 2.7 or less, more preferably 2.4 or less, and even more preferably 2.1 or less. do. Further, the preferable lower limit is 1.0 or more, more preferably 1.3 or more, and even more preferably 1.6 or more.

[Content of ₂ SiO components/(Content of ₅ P ₂ O components+Content of Li ₂ O component+Content of Na ₂ O component+Content of K ₂ O component)] may be set to 4.5 or more. When it is 4.5 or more, it becomes easier to obtain a desired crystal phase.
Therefore, the lower limit is preferably 4.5 or more, more preferably 5.0 or more. In addition, by setting [content of SiO ₂ components/(content of P ₂ O ₅ components + content of Li ₂ O component + content of Na ₂ O component + content of K ₂ O component)] to 20.0 or less, desired crystals can be obtained. It is possible to precipitate a phase and suppress excessive increase in viscosity and deterioration of solubility. Therefore, the upper limit of [SiO ₂ component content/(P ₂ O ₅ component content + Li ₂ O component content + Na ₂ O component content + K ₂ O component content)] is, for example, 20.0 or less, 10.0 or less , or 7.5 or less.

[Content of K ₂ O component/Content of ZrO ₂ component] may be greater than 0 and less than 0.5. When it is less than 0.5, it becomes easier to obtain a desired crystalline phase, and when it is more than 0, deterioration in viscosity and meltability can be suppressed, and productivity can be easily improved.
Therefore, the upper limit of [K ₂ O component content/ZrO ₂ component content] is preferably less than 0.5, more preferably 0.4 or less, and even more preferably 0.3 or less. Further, the lower limit is preferably greater than 0, more preferably 0.1 or more.

[(Content of K ₂ O component + content of ₃ Al ₂ O components)/content of ₂ ZrO components] may be greater than 0 and not more than 0.85. When it is 0.85 or less, it becomes easier to suppress the formation of lithium aluminum silicate crystal phase, and when it is more than 0, it becomes easier to stabilize the glass.
Therefore, the preferable upper limit of [(content of K ₂ O component + content of ₃ components of Al ₂ O)/content of ₂ components of ZrO] is 0.85 or less, more preferably 0.80 or less, still more preferably 0.75 or less. do. Further, the preferable lower limit is more than 0, more preferably 0.1 or more, and still more preferably 0.2 or more.

[(Content of K ₂ O component + content of ₃ Al ₂ O components)/(content of ZnO component + content of ₂ ZrO components)] may be greater than 0 and not more than 0.95. When it is 0.95 or less, it becomes easier to suppress the formation of lithium aluminum silicate crystal phase, and when it is more than 0, it becomes easier to stabilize the glass.
Therefore, the preferable upper limit of [(content of K ₂ O component + content of ₃ components of Al ₂ O)/(content of ZnO component + content of ₂ components of ZrO)] is 0.95 or less, more preferably 0.90 or less, even more preferably shall be 0.85 or less. Further, the preferable lower limit is more than 0, more preferably 0.1 or more, and still more preferably 0.2 or more.

The crystallized glass of the present invention contains Bi ₂ O ₃ , Cr ₂ O ₃ , CuO, La ₂ O ₃ , MnO, MoO ₃ , PbO, V ₂ O ₅ , WO ₃ , within a range that does not impair the effects of the present invention. Each of the _three Y ₂ O components may or may not be included. Not including these components has the effect of preventing deterioration of transmittance.

Further, the crystallized glass may or may not contain other components not mentioned above as long as the characteristics of the crystallized glass of the present invention are not impaired. For example, metal components such as Yb, Lu, Fe, Co, Ni, and Ag (including oxides of these metals) are used.

Further, as a fining agent for glass, in addition to _Sb2O3 , _SnO2 , _CeO2, _As2O3 , and one or more selected from the group consisting of F, _NOx , and SOx may or may not be included. However _, the upper limit of the content of the fining agent can be preferably set to 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, and most preferably 0.6% or less.

On the other hand, since there is a trend in recent years to refrain from using Pb, Th, Tl, Os, Be, Cl, and Se as harmful chemical substances, it is preferable that these components are not substantially contained.

The Vickers hardness (Hv0.2: Hv at a test load of 200 gf) of the crystallized glass of the present invention is preferably 630 or more, more preferably 690 or more, and still more preferably 710 or more. Vickers hardness tends to increase by decreasing the ZrO ₂ component, increasing the Li ₂ O component, or decreasing the K ₂ O component.

When the crystallized glass of the present invention has a thickness of 1 mm, the transmittance at a wavelength of 450 nm is 0% to 80%, and may be, for example, 20% or more, 30% or more, or 50% or more. Further, it may be less than 20%. The transmittance can be adjusted by adjusting the content of the ZrO ₂ component, Li ₂ O component, or K ₂ O component.

The crystallized glass of the present invention can be produced by the following method. Specifically, raw glass is manufactured by uniformly mixing raw materials so that each component is within a predetermined content range, and melt-molding. Next, this raw glass is crystallized to produce crystallized glass.

The heat treatment for crystal precipitation may be carried out in one step or may be carried out in two steps.
In the two-step heat treatment, first a nucleation step is 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 the nucleation step.
The first temperature of the two-step heat treatment is preferably 400°C to 680°C, more preferably 450°C to 650°C, still more preferably 500°C to 600°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-step heat treatment is preferably 680°C or higher, for example 700°C to 800°C, preferably 700°C to 750°C. The holding time at the second temperature is preferably 30 minutes to 600 minutes, more preferably 60 minutes to 400 minutes.

In the one-stage heat treatment, the nucleation step and the crystal growth step are carried out consecutively at a single temperature step. Usually, 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.
In the case of one-stage heat treatment, the heat treatment temperature is preferably 680° C. or higher, for example, 700° C. to 800° C., and preferably 700° C. to 750° C. The holding time at the heat treatment temperature is preferably 30 minutes to 500 minutes, and more preferably 60 minutes to 400 minutes.

A compressive stress layer may be formed on the surface by strengthening the crystallized glass. As a method for forming a compressive stress layer in strengthened crystallized glass, for example, an alkali component present in the surface layer of the crystallized glass is exchange-reacted with an alkali component having a larger ionic radius to form a compressive stress layer in the surface layer. There is a chemical strengthening method to do this.

The chemical strengthening method can be carried out, for example, in the following steps. The crystallized glass is brought into contact with or immersed in a molten salt containing potassium or sodium, such as potassium nitrate (KNO ₃ ), sodium nitrate (NaNO ₃ ), or a mixed or complex salt thereof. The treatment of contacting or immersing in this molten salt (chemical strengthening treatment) may be carried out in one step or in two steps.

In the case of one-step chemical strengthening treatment, for example, the material is brought into contact with or immersed in a salt containing potassium or sodium, or a mixed salt thereof heated at 350° C. to 550° C. for 1 minute to 1440 minutes.
In the case of a two-step chemical strengthening treatment, for example, first, it is contacted or immersed in a sodium salt or a mixed salt of a potassium salt and a sodium salt heated at 350° C. to 550° C. for 1 minute to 1440 minutes, preferably 30 minutes to 1000 minutes. . Continuously, secondly, it is brought into contact with or immersed in potassium salt or a mixed salt of potassium salt and sodium salt heated at 350° C. to 550° C. for 1 minute to 1440 minutes, preferably 60 minutes to 600 minutes.

The present invention contains lithium disilicate as the main crystal phase, but can be chemically strengthened in two stages, where the lithium is exchanged for sodium, and then the sodium is exchanged for potassium. This two-stage chemical strengthening can increase the compressive stress value of the outermost surface.

The compressive stress value (CS) of the outermost surface of the strengthened crystallized glass is preferably 400 MPa or more, more preferably 500 MPa or more. The depth (DOL zero) when the compressive stress of the compressive stress layer is 0 MPa is preferably 120 μm or more, more preferably 130 μm or more. The central tensile stress (CT) can be, for example, 30 MPa or more, or 40 MPa or more.

Examples 1 to 27, Comparative Examples 1 and 2
1. Production of Crystallized Glass As raw materials for each component of the crystallized glass, raw materials such as oxides, hydroxides, carbonates, nitrates, fluorides, chlorides, metaphosphate compounds, etc. corresponding to each component were selected, and these raw materials were weighed and mixed uniformly to obtain the compositions shown in Tables 1 to 4. Comparative Example 1 is Example 9 of Patent Document 2.
In the table, (Si+Li)/Al is an abbreviation for [( _SiO2 component content + _Li2O component content)/ _Al2O3 component content], (K+Al)/Zr is an abbreviation for [( _K2O component content + _Al2O3 component content)/ _ZrO2 component content], and (P+K+ _Mg + _Al )/Zr is _an abbreviation for [( _P2O5 component content + _K2O component content + _MgO component content + _Al2O3 component content)/ _ZrO2 component content].

Next, the mixed raw materials were put into a platinum crucible and melted in an electric furnace at 1300°C to 1600°C for 2 to 24 hours depending on the melting difficulty of the glass composition. Thereafter, the molten glass was stirred to homogenize, the temperature was lowered to 1000°C to 1450°C, and then poured into a mold and slowly cooled to produce raw glass. The obtained raw glass was heated under the crystallization conditions shown 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 (D8 Discover, manufactured by Bruker). The precipitated crystal phases are listed in Tables 1 to 4. In addition, in the table, cri. is an abbreviation for α-cristobalite, LS2 is an abbreviation for lithium disilicate, LS is an abbreviation for lithium monosilicate crystal, Quartz is an abbreviation for quartz, and Petalite is an abbreviation for petalite. It is. The main crystalline phases in all examples were α-cristobalite and lithium disilicate.

2. Evaluation of Crystallized Glass The prepared crystallized glass was cut and ground to prepare samples, and the following evaluations were made. The results are shown in Tables 1 to 4.
(1) Transmittance (λ5, λ80)
The light transmittance including reflection loss at a thickness of 1 mm was measured using a spectrophotometer (manufactured by Hitachi High Technologies, Model U-4000). The wavelength (λ5) at which the transmittance was 5% and the wavelength (λ80) at which the transmittance was 80% were determined.

(2) Transmittance Light transmittance including reflection loss at 450 nm at a thickness of 1 mm was measured using a spectrophotometer (manufactured by Hitachi High Technologies, Model U-4000).

(3) Vickers hardness (Hv0.2)
The load applied when a pyramidal indentation was made on the surface of the sample using a diamond pyramid indenter with a facing angle of 136° was divided by the surface area ( ^mm2 ) calculated from the length of the indentation. The measurement was performed using a micro Vickers hardness tester HMV-G21D manufactured by Shimadzu Corporation, with a test load of 200 gf and a holding time of 10 seconds.

3. Chemical Strengthening As Comparative Example 2, crystallized glass having the following composition (% by mass) was used. This crystallized glass contains petalite and lithium disilicate as main crystal phases.
78.3% of SiO ₂ component, 8.1% of Al ₂ O ₃ component, 0.2% of B ₂ O ₃ component, 11.9% of Li ₂ O component, 1.7% of Na ₂ O component. , K ₂ O component 0.0%, ZnO component 0.0%, ZrO ₂ component 4.0%, P ₂ O ₅ component 2.2%.

In Examples 8, 24, 27, and Comparative Example 2, the produced crystallized glass was cut and ground to obtain crystallized glass substrates having the material thicknesses (substrate thicknesses) shown in Table 5. Using this crystallized glass substrate as a base material, primary strengthening (first stage) and secondary strengthening (second stage) were performed under the conditions shown in Table 5 to obtain strengthened crystallized glass.

For the strengthened crystallized glass, the compressive stress value (CS [MPa]) at the outermost surface was measured using a glass surface stress meter FSM-6000LE series manufactured by Orihara Seisakusho. A light source with a wavelength of 596 nm was used as the light source of the measuring device. For the photoelastic constant at a wavelength of 596 nm, 28.2 was used as a representative value in the examples, and 26.2 was used in the comparative examples. The results are shown in Table 5.

The depth (DOL zero [μm]) and center tensile stress (CT [(MPa)]) when the compressive stress of the compressive stress layer is 0 MPa were measured using a scattered light photoelastic stress meter (manufactured by Orihara Seisakusho, SLP-1000). It was measured using A light source with a wavelength of 518 nm was used as the measurement light source. For the photoelastic constant at a wavelength of 518 nm, 28.8 was used as a representative value in the examples, and 26.6 was used in the comparative examples. The results are shown in Table 5.

Although some embodiments and/or examples of the present invention have been described in detail above, those skilled in the art will appreciate that these exemplary embodiments and/or It is easy to make many changes to the embodiment. Accordingly, many of these modifications are within the scope of this invention.
The documents mentioned in this specification and the content of the application that is the basis of the priority right under the Paris Convention of this application are all incorporated by reference.

Claims

Contains α-cristobalite and lithium disilicate as the main crystal phase,
In terms of oxide mass%,
Content of two SiO components: 65.0% to 85.0%,
Content of three Al 2 O components: 1.5% to 5.9%,
Content of P 2 O 5 components: more than 0% and less than 5.0%,
Content of Li 2 O component 5.0% to 10.8%,
Content of two ZrO components: 4.0% to 12.5%,
and
[(Content of 2 SiO components + Content of Li 2 O component)/Content of 3 Al 2 O components] More than 13.9,
A crystallized glass characterized by:
In terms of oxide mass%,
Content of three B 2 O components: 0% to 5.0%,
Content of Na 2 O component 0% to 5.0%,
K 2 O component content 0% to 5.0%,
MgO component content 0% to 5.0%,
Content of CaO component: 0% to 5.0%,
Content of ZnO component: 0% to 5.0%,
Content of two TiO components: 0% to 5.0%,
Content of Gd 2 O 3 components 0% to 5.0%,
Content of three Sb 2 O components: 0% to 3.0%,
Content of Nb 2 O 5 components 0% to 3.0%,
The crystallized glass according to claim 1, characterized in that:
The crystallized glass according to claim 1 or 2, characterized in that the content of the ZrO 2 component is 4.7% to 12.5%.
3. The crystallized glass according to claim 1, wherein the content of ZrO2 component is more than 7% and not more than 12.5%.
In terms of oxide mass%,
[(Content of K 2 O component + content of 3 components of Al 2 O) / content of 2 components of ZrO] less than 0.88,
The crystallized glass according to claim 1 or 2, characterized in that:
In terms of oxide mass%,
[(Content of P 2 O 5 components + content of K 2 O component + content of MgO component + content of 3 Al 2 O components) / content of 2 ZrO components] less than 1.32,
The crystallized glass according to claim 1 or 2, characterized in that:
The crystallized glass according to claim 1 or 2, which has a compressive stress layer on the surface.
The crystallized glass according to claim 1 or 2, which is used for a glass member of a smartphone.