Crystallized glass, chemically strengthened glass, glass, and three-dimensionally shaped cover glass

Abstract

The present invention pertains to a crystallized glass which has a crystal phase and an amorphous phase. The composition of the crystallized glass includes, as indicated in oxide-based mole percentage, 55-70% of SiO2, 15-27.0% of Li2O, 0.1-2.6% of Al2O3, 0.5-5% of P2O5, and 0.5-2.6% of ZrO2. The content proportion of the crystal phase in the crystallized glass is 50-85 mass%. The crystal phase contains Li2Si2O5 crystals. The content proportion of the Li2Si2O5 crystals in the crystal phase is not less than 80 mass%.

Description

Crystallized glass, chemically strengthened glass, glass, and three-dimensional cover glass

[0001] The present invention relates to crystallized glass, chemically strengthened glass, glass, and three-dimensionally shaped cover glass.

[0002] Thin, high-strength chemically strengthened glass is used as the cover glass for display devices of mobile devices such as mobile phones and smartphones, and for in-vehicle display components such as instrument panels and head-up displays (HUDs). These display devices may require a three-dimensional (curved) cover glass to improve operability and visibility. Three-dimensional cover glass is produced by heating a flat glass plate and bending it using a forming mold (also referred to as three-dimensional bending or three-dimensional forming).

[0003] As an index of the strength of such a cover glass, Young's modulus and fracture toughness value K ＩＣ Glass-ceramics have been attracting attention as a way to realize high-strength cover glass with high values ​​for these properties. In particular, considering that chemical strengthening treatment is also performed, it is considered to apply Li-based glass-ceramics containing lithium to the cover glass.

[0004] As a crystalline phase in high-strength Li-based crystallized glass, lithium disilicate (Li ２ Si ２ O ５ For example, Patent Document 1 discloses a method for producing a silicon dioxide film using SiO ２ Ingredients, Al ２ O ３ Ingredients: Li ２ O component, ZrO ２ Ingredients, and P ２ O ５ Crystallized glass articles are disclosed that contain lithium silicate crystalline phases (one or both of lithium metasilicate and lithium disilicate) with component proportions within specified ranges.

[0005] Japanese Patent Application Publication No. 2023-506666

[0006] However, the inventors have found through their research that increasing the crystallinity of crystallized glass in order to achieve higher strength tends to decrease transparency, and lithium disilicate crystals in particular tend to become cloudy and white.

[0007] In fact, it has been found that the crystallized glass product disclosed in Patent Document 1 exhibits a decrease in transparency when the degree of crystallization is increased, and the desired transparency cannot be achieved.

[0008] In addition, the crystalline phase of crystallized glass depends on the matrix composition of the glass before crystallization, so it is necessary to make the matrix composition close to the stoichiometric ratio of the target crystal phase.However, lithium disilicate crystal is in the composition range where phase separation is likely to occur, and the glass itself before crystallization is likely to be cloudy and white.On the other hand, the above-mentioned phase separation is advantageous for the generation of crystal nuclei, and when it is made into crystallized glass, it can be said that it is easy to increase its crystallinity.

[0009] Therefore, an object of the present invention is to provide a crystallized glass that combines high transparency and high strength. Another object is to provide a chemically strengthened glass of the crystallized glass, and a glass suitable as a mother glass for obtaining the crystallized glass. Another object is to provide a three-dimensional cover glass made of the chemically strengthened glass.

[0010] As a result of intensive research into the above-mentioned problems, the present inventors have determined that the composition of the crystallized glass should be within a specific range, and that ZrO ２ The present inventors have found that by controlling the content ratio of the compound (I), it is possible to suitably control phase separation, maintain high transparency even when the crystallinity is increased, and achieve higher strength, and have completed the present invention.

[0011] That is, the gist of the present invention relates to the following [1] to

[18] . [1] A crystallized glass having a crystalline phase and an amorphous phase, wherein the composition of the crystallized glass is expressed in mole percentage based on oxides as follows: SiO ２ 55-70%, Li ２ O 15-27.0%, Al ２ O ３ 0.1-2.6%, P ２ O ５ 0.5 to 5%, and ZrO ２0.5 to 2.6%, the content of the crystalline phase in the crystallized glass is 50 to 85 mass%, and the crystalline phase is Li ２ Si ２ O ５ The Li in the crystalline phase ２ Si ２ O ５ The crystal content is 80% by mass or more. [2] SiO ２ , Al ２ O ３ , Li ２ O, and ZrO ２ Using the content ratio expressed in mole percentage, the formula (1): {([SiO ２ ]+[Al ２ O ３ ]+[Li ２ O]) / [ZrO ２ ]} is 18 or more. [3] The composition of the crystallized glass is expressed in mole percentage based on oxides as follows: Na ２ O 0.1 to 5%, and K ２ [4] The glass-ceramics according to the above [1] or [2], further satisfying the following: LiO 0.1 to 3%. [5] The glass-ceramics according to the above [1] or [2], further satisfying the following: LiO 0.1 to 3%. [6] The glass-ceramics according to the above [1] or [2], further satisfying the following: LiO 0.1 to 3%. [7] The glass-ceramics according to the above [1] or [2], ２ Si ２ O ５ The glass-ceramics according to any one of the above [1] to [3], wherein the half-width of the peak derived from the crystal is 0.1 to 0.4. [5] The composition of the amorphous phase is expressed in mole percentage based on oxides as follows: SiO ２ 50-80%, Li ２ O 0.1-17%, Al ２ O ３ 0.1 to 20%, P ２ O ５ 0.1 to 15%, and ZrO ２[6] The glass-ceramics according to any one of [1] to [4], which has a Young's modulus of 95 to 120 GPa. [7] The glass-ceramics according to any one of [1] to [6], which has a haze value of 0.02 to 1.00%. [8] The glass-ceramics according to any one of [1] to [6], which has a fracture toughness value of 1.00 MPa m １／２ [9] The glass-ceramics according to any one of [1] to [8], wherein the average particle size of the crystals constituting the crystalline phase is 20 to 200 nm.

[0012]

[10] Chemically strengthened glass having a compressive stress layer formed by ion exchange on the surface layer of the crystallized glass according to any one of [1] to [9].

[11] Na ２ The content of O is determined by the ratio of Na in the composition of the crystallized glass. ２

[12] The chemically strengthened glass according to

[10] above, wherein the Li content is higher than the O content, and the difference is 1 mol % or more.

[13] The chemically strengthened glass according to

[10] above or

[11] above, wherein the surface compressive stress is 300 MPa or more and the compressive stress layer depth is 50 μm or more.

[14] In the X-ray diffraction pattern of the surface using Cu-Kα radiation, ２ Si ２ O ５

[10] to

[12] , wherein, among the peaks derived from crystals, there is one or more peaks having a peak shift amount of 0.02 ° or more from the peak before the ion exchange. Chemically strengthened glass according to any one of the above.

[0013]

[14] The composition in terms of mole percentage based on oxide is SiO ２ 55-70%, Li ２ O 15-27.0%, Al ２ O ３ 0.1-2.6%, P ２ O ５ 0.5 to 5%, and ZrO ２

[15] Glass that satisfies the following conditions: 0.5 to 2.6%. ２ Si ２ O ５The glass according to the above

[14] , wherein a crystalline phase containing SiO is formed.

[16] ２ , Al ２ O ３ , Li ２ O, and ZrO ２ Using the content ratio expressed in mole percentage, the formula (1)": {([SiO ２ ]+[Al ２ O ３ ]+[Li ２ O]) / [ZrO ２

[17] The glass according to the above

[14] or

[15] , wherein the value represented by the formula {R(x,y)} is 18 or more.

[17] The composition expressed in mole percentage based on oxides is: Na ２ O 0.1 to 5%, and K ２ The glass according to any one of the above

[14] to

[16] , further satisfying O 0.1 to 3%.

[0014]

[18] A three-dimensional cover glass made of the chemically strengthened glass according to any one of

[10] to

[13] , wherein the chemically strengthened glass has a three-dimensional shape having a curved surface portion that forms a three-dimensional curved surface.

[0015] According to the present invention, it is possible to obtain a crystallized glass that combines high transparency and high strength, and a glass suitable as a mother glass for obtaining the crystallized glass. Furthermore, it is also possible to obtain a chemically strengthened glass that achieves higher strength by chemically strengthening the crystallized glass. Furthermore, it is also possible to obtain a three-dimensional cover glass by adding a three-dimensional curved surface portion to the crystallized glass or chemically strengthened glass. The three-dimensional cover glass is suitable as a cover glass for display devices of mobile devices such as mobile phones and smartphones, and for in-vehicle display components such as instrument panels and HUDs.

[0016] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the embodiments described below. Furthermore, in this specification, the term "to" indicating a range of values ​​is used to mean that the values ​​before and after it are included as the lower and upper limits. In this specification, mass % and weight % have the same meaning.

[0017] <<Ceramics>> The crystallized glass according to this embodiment has a crystalline phase and an amorphous phase, and its composition satisfies the following in terms of mole percentage based on oxides: SiO ２ 55-70%, Li ２ O 15-27.0%, Al ２ O ３ 0.1-2.6%, P ２ O ５ 0.5 to 5%, and ZrO ２ 0.5 to 2.6%. In the crystallized glass according to this embodiment, the content of the crystalline phase is 50 to 85 mass %. The crystalline phase is composed of lithium disilicate (Li ２ Si ２ O ５ ) crystals, and the content of the lithium disilicate crystals in the crystalline phase is 80 mass % or more.

[0018] In this specification, the composition of crystallized glass can be identified by using conventionally known methods.For example, the composition of crystallized glass can be identified by wet chemical analysis or quantitative analysis using fluorescent X-ray calibration curve.In addition, the composition (mother composition) of amorphous glass (mother glass) before crystallization is the same as the composition of crystallized glass.The composition of the amorphous phase (residual glass phase) in crystallized glass is strictly different from the mother composition, and the composition of amorphous phase can also be determined from the composition of crystallized glass and the composition and content of crystalline phase.

[0019] The crystallized glass in this specification can be determined to have a crystalline phase by observing diffraction peaks indicative of crystals in an XRD pattern obtained by powder X-ray diffraction (XRD). The crystallized glass has a crystalline phase in which crystals are precipitated by heat-treating amorphous glass (mother glass) in which no diffraction peaks indicative of crystals are observed. The XRD measurement is performed using CuKα radiation at a 2θ range of 10° to 80°. From the diffraction pattern and diffraction intensity obtained as a result of the measurement, Rietveld analysis can be used to identify the crystalline structure of the crystals constituting the crystalline phase, the content ratio of each crystalline phase, and the total content ratio of the crystalline phases (degree of crystallization). The Rietveld method is described in "Crystal Analysis Handbook," edited by the Editorial Committee of the Crystallographic Society of Japan (Kyoritsu Shuppan, 1999, pp. 492-499).

[0020] As described above, the composition of the crystallized glass according to this embodiment satisfies the following in terms of mole percentage based on oxides: SiO ２ 55-70%, Li ２ O 15-27.0%, Al ２ O ３ 0.1-2.6%, P ２ O ５ 0.5 to 5%, and ZrO ２ 0.5 to 2.6%.

[0021] In addition to the above, the composition of the crystallized glass is Na ２ O 0.1 to 5%, and K ２ It is preferable to further satisfy at least one of the following conditions: O 0.1 to 3%, and it is more preferable to satisfy both of the above conditions.

[0022] Each component that can be contained in the crystallized glass will be described below.

[0023] SiO ２ is a component that constitutes the glass network and also a component that constitutes lithium disilicate crystals. ２The content ratio of is 55 to 70%, preferably 56 to 69%, and more preferably 57 to 68%. Here, from the viewpoint of facilitating the formation of lithium disilicate crystals, the content ratio is preferably 55% or more, more preferably 56% or more, and even more preferably 57% or more. Furthermore, from the viewpoint of facilitating the formation of lithium disilicate crystals and enhancing the meltability of the glass, the content ratio is preferably 70% or less, more preferably 69.5% or less, even more preferably 69% or less, and even more preferably 68% or less.

[0024] Li ２ O is a component of lithium disilicate crystals, and is also a component that forms compressive stress near the surface of the crystallized glass by being ion-exchanged with Na ions. ２ The O content is preferably 15 to 27.0%, more preferably 16 to 26.8%, and even more preferably 17 to 26.6%. Alternatively, it may be 15 to 26.4%. From the viewpoint of facilitating the formation of lithium disilicate crystals and increasing compressive stress, the O content is preferably 15% or more, more preferably 16% or more, and even more preferably 17% or more. From the viewpoint of facilitating the formation of lithium disilicate crystals and increasing the chemical durability of the glass, the O content is preferably 27.0% or less, and may be 26.8% or less, 26.6% or less, 26.5% or less, 26.4% or less, 26.3% or less, or 26.2% or less.

[0025] Al ２ O ３ is a component that improves ion exchangeability during chemical strengthening treatment and increases the surface compressive stress after chemical strengthening treatment. ２ O ３The content is preferably 0.1 to 2.6%, more preferably 0.3 to 2.5%, and even more preferably 0.5 to 2.4%. Here, from the viewpoint of performing chemical strengthening treatment appropriately, the content is preferably 0.1% or more, more preferably 0.3% or more, and even more preferably 0.5% or more, and may be 1.0% or more, 1.5% or more, 1.6% or more, or 2.0% or more. Furthermore, from the viewpoint of facilitating the formation of lithium disilicate crystals, the content is preferably 2.6% or less, more preferably 2.5% or less, and even more preferably 2.4% or less.

[0026] P ２ O ５ is a component that promotes crystallization. ２ O ５ The content of is preferably 0.5 to 5%, more preferably 0.8 to 4.5%, and even more preferably 1 to 4%. From the viewpoint of facilitating crystallization, the content is preferably 0.5% or more, more preferably 0.8% or more, and even more preferably 1% or more. Furthermore, from the viewpoint of suppressing phase separation during melting and a decrease in acid resistance, the content is preferably 5% or less, more preferably 4.5% or less, and even more preferably 4% or less.

[0027] ZrO ２ is a thickening component that increases the viscosity when melted, and at the same time, is a component that increases the surface compressive stress due to ion exchange. ２ It has been found that by adding an appropriate amount of ZrO, it is possible to suitably control phase separation so that crystallization is facilitated while maintaining high transparency. As a result, when the glass is made into a crystallized glass, the crystallization degree can be increased while maintaining high transparency, and higher strength can be achieved. ２The content ratio is preferably 0.5 to 2.6%, more preferably 1 to 2.5%, and even more preferably 1.5 to 2.4%. Here, from the viewpoint of controlling phase separation and acting as a thickening component to slow the growth rate of crystals that become crystalline phases and form fine crystals, thereby realizing higher transparency of the crystallized glass, the content ratio is preferably 0.5% or more, more preferably 1% or more, and even more preferably 1.5% or more. Furthermore, from the viewpoint of suppressing devitrification during melting, the content ratio is preferably 2.6% or less, more preferably 2.5% or less, even more preferably 2.4% or less, and may be 2.3% or less, 2.2% or less, or 2.1% or less.

[0028] Furthermore, ZrO in the crystallized glass according to this embodiment ２ The content ratio is preferably 1 to 6 mass% when expressed as a mass percentage based on oxides. Here, from the viewpoint of controlling phase separation and acting as a thickening component to slow the growth rate of crystals that become crystalline phases and form fine crystals, thereby realizing higher transparency of the crystallized glass, the content ratio is preferably 1 mass% or more, more preferably 2.5 mass% or more, even more preferably 3.2 mass% or more, and even more preferably 3.7 mass% or more. Furthermore, from the viewpoint of suppressing devitrification during melting, the content ratio is preferably 6 mass% or less, more preferably less than 5 mass%, even more preferably 4.8 mass% or less, and may be 4.5 mass% or less, or may be 4.4 mass% or less.

[0029] Na ２ O is a component that forms compressive stress by ion-exchanging with K ions, and the inclusion of a small amount of O can increase the stability of the glass. ２ The content of O is preferably 0 to 5%, more preferably 0.1 to 5%, more preferably 0.5 to 4.5%, even more preferably 1 to 4%, and even more preferably 1.5 to 3.5%. ２ The content of O is 0%, that is, it may not be contained, but Na ２When O is contained, from the viewpoint of increasing compressive stress and improving stability, the content is preferably 0.1% or more, more preferably 0.5% or more, even more preferably 1% or more, and even more preferably 1.5% or more. Also, from the viewpoint of maintaining chemical durability, the content is preferably 5% or less, more preferably 4.5% or less, even more preferably 4% or less, and even more preferably 3.5% or less.

[0030] K ２ O is a component that enhances chemical strengthening properties and suppresses phase separation. ２ The content of O is preferably 0 to 3%, more preferably 0.1 to 3%, and even more preferably 0.5 to 2.5%. ２ The content of O is 0%, that is, it may not be contained, but K ２ When O is contained, the content is preferably 0.1% or more, more preferably 0.3% or more, and even more preferably 0.5% or more from the viewpoint of enhancing the stability of the glass, and is preferably 3% or less, more preferably 2.5% or less from the viewpoint of maintaining chemical durability.

[0031] BaO is a component that improves the meltability of glass. The BaO content in the crystallized glass is preferably 0 to 5%, more preferably 0.1 to 4%, and even more preferably 0.5 to 3%. Here, BaO does not have to be contained, but if it is contained, from the viewpoints of meltability and strength, the content is preferably 0.1% or more, more preferably 0.5% or more. Furthermore, from the viewpoint of maintaining good ion exchange performance, the content is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0032] MgO, CaO, and SrO, which are alkaline earth metals other than BaO, are also components that, like BaO, improve the meltability of the glass. The total content of MgO, CaO, SrO, and BaO is preferably 0 to 5%, more preferably 0.1 to 4%, and even more preferably 0.5 to 3%. Although alkaline earth metals are not required, if they are contained, from the viewpoints of meltability and strength, the total content is preferably 0.1% or more, more preferably 0.5% or more. Furthermore, from the viewpoint of maintaining good ion exchange performance, the total content is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0033] The respective contents of MgO, CaO, and SrO are preferably 0 to 4%, more preferably 0.1 to 3%, even more preferably 0.5 to 3%, even more preferably 1 to 2.5%, and particularly preferably 1 to 2%. MgO, CaO, and SrO do not necessarily need to be contained, but if they are contained, from the viewpoint of enhancing the stability of the glass, the respective contents are preferably 0.1% or more, more preferably 0.5% or more, and even more preferably 1% or more. From the viewpoint of maintaining good ion exchange performance, the respective contents are preferably 4% or less, more preferably 3% or less, even more preferably 2.5% or less, and even more preferably 2% or less.

[0034] Y ２ O ３ Y is a thickening component that increases the viscosity during melting, and at the same time, it is a component that increases the mechanical strength of the glass. It is also a component that increases the refractive index. ２ O ３ The content of Y is preferably 0 to 5%, more preferably 0.1 to 4%, and even more preferably 0.3 to 3%. ２ O ３ Although it is not necessary to contain, when it is contained, it acts as a thickening component, slows down the growth rate of the crystal that becomes crystalline phase, and makes it into minute crystals, so that the high transparency of crystallized glass is realized, so that the content ratio is preferably 0.1% or more, more preferably 0.3% or more.In addition, from the viewpoint of suppressing mismatch during melting, the content ratio is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0035] TiO ２ is a thickening component that increases the viscosity when melted, and at the same time, is a component that increases UV resistance. ２ The content of TiO is preferably 0 to 5%, more preferably 0.1 to 4%, and even more preferably 0.5 to 3%. ２ Although it is not necessary to contain, when it is contained, it acts as a thickening component, slows down the growth rate of the crystals that become crystalline phase, and makes them into minute crystals, so that the high transparency of the crystallized glass can be realized, and the content ratio is preferably 0.1% or more, more preferably 0.5% or more.In addition, from the viewpoint of suppressing the decrease in haze value due to coloring, the content ratio is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0036] SnO ２ is a fining agent during melting and also a component that forms crystal nuclei. ２ The content of SnO is preferably 0 to 2%, more preferably 0.1 to 1.5%, and even more preferably 0.5 to 1%. ２ Although it is not necessary to contain, when it is contained, it acts as a component that generates the nucleus of crystal, and by forming minute crystals, from the viewpoint of realizing high transparency of crystallized glass, the content ratio is preferably 0.1% or more, more preferably 0.5% or more.In addition, from the viewpoint of suppressing the defects caused by unmelted matter, the content ratio is preferably 2% or less, more preferably 1.5% or less, and even more preferably 1% or less.

[0037] ZnO is a component that improves the meltability of glass. The ZnO content in the crystallized glass is preferably 0 to 5%, more preferably 0.1 to 4%, and even more preferably 0.2 to 1%. While ZnO need not be contained, if it is contained, its content may be 0.1% or more, or even 0.2% or more. From the viewpoint of improving weather resistance, the content is preferably 5% or less, more preferably 4% or less, even more preferably 1% or less, even more preferably 0.7% or less, and particularly preferably 0.5% or less.

[0038] B ２ O３ is a component that improves chipping resistance and melting property. ２ O ３ The content of B is preferably 0 to 10%, more preferably 0.1 to 9%, and even more preferably 0.2 to 8%. ２ O ３ Although it is not necessary to contain it, if it is contained, from the viewpoint of obtaining good chipping resistance and melting property, the content ratio is preferably 0.1% or more, more preferably 0.2% or more. Furthermore, from the viewpoint of suppressing the occurrence of striae and phase separation during melting and maintaining the quality of the crystallized glass, the content ratio is preferably 10% or less, more preferably 9% or less, and even more preferably 8% or less.

[0039] La ２ O ３ , Nb ２ O ５ and Ta ２ O ５ Is Y ２ O ３ Similarly to La, it has the effect of increasing the mechanical strength of the glass and may be contained to increase the refractive index. ２ O ３ , Nb ２ O ５ and Ta ２ O ５ The total content of these components is preferably 0 to 3%, more preferably 0.5 to 2%. These components do not necessarily have to be contained, but if they are contained, the total content is preferably 0.5% or more from the viewpoint of increasing the refractive index. Furthermore, the total content is preferably 3% or less, more preferably 2% or less from the viewpoint of suppressing devitrification of the glass during melting.

[0040] CeO ２ has the effect of oxidizing the glass, and the glass-ceramic becomes SnO ２ When the content is large, SnO ２ The reduction of CeO in the glass-ceramics to SnO, which is a coloring component, can be suppressed, thereby suppressing coloration. ２The content of CeO is preferably 0 to 1.5%, more preferably 0.03 to 1.5%, even more preferably 0.05 to 1%, and even more preferably 0.07 to 1%. ２ However, if it is contained, the content is preferably 0.03% or more, more preferably 0.05% or more, and even more preferably 0.07% or more, from the viewpoint of suppressing coloration due to SnO. ２ From the viewpoint of suppressing coloration of the glass due to the presence of arsenic, the content is preferably 1.5% or less, and more preferably 1% or less.

[0041] Furthermore, a coloring component may be added to the glass-ceramic to the extent that it does not impede the achievement of the desired properties. ３ O ４ , MnO ２ , Fe ２ O ３ , NiO, CuO, Cr ２ O ３ , V ２ O ５ , Bi ２ O ３ , SeO ２ , Er ２ O ３ , Nd ２ O ３ etc. The content ratio of the above coloring components in the crystallized glass is preferably in the range of 1% or less in total. Furthermore, if it is desired to increase the light transmittance of the crystallized glass, it is preferable that these components are not substantially contained. In this specification, "substantially not contained" means that the content is below the impurity level contained in raw materials, etc., that is, it is not intentionally added. In this specification, when it is stated that a certain component is not substantially contained, the content ratio of the component is specifically, for example, less than 0.03%.

[0042] In addition, SO is used as a fining agent when melting glass. ３ , chloride, fluoride, As ２ O ３ , Sb ２ O ３The content of each of the fining agents is preferably 0.3% or less, more preferably 0.1% or less, and most preferably substantially none.

[0043] The composition of the crystallized glass according to this embodiment is SiO ２ , Al ２ O ３ , Li ２ O, and ZrO ２ It is preferable that the value represented by the following formula (1) using the content ratio expressed in mole percentage of [SiO ２ ] is SiO in the crystallized glass ２ The same applies to other components. Formula (1): {([SiO ２ ]+[Al ２ O ３ ]+[Li ２ O]) / [ZrO ２ ]

[0044] The molecule in the above formula (1) ([SiO ２ ]+[Al ２ O ３ ]+[Li ２ O]) means the total content ratio of the main components of the crystallized glass, and is calculated by dividing it by the devitrification suppressing component ZrO ２ Dividing this by the content ratio of the sintered body gives an index of crystallinity. The above value is preferably 18 or more, more preferably 20 or more, and even more preferably 20 to 500. Here, from the viewpoint of increasing the crystallinity, the above value is preferably 18 or more, more preferably 20 or more, even more preferably 25 or more, even more preferably 30 or more, even more preferably 34 or more, and may be 40 or more, or may be 45 or more. Furthermore, from the viewpoint of suppressing devitrification, the above value is preferably 500 or less, more preferably 400 or less, even more preferably 300 or less, and even more preferably 200 or less.

[0045] The composition of the crystallized glass according to this embodiment is SiO ２ and ZrO ２ Using the content ratio expressed in mole percentage, it is preferable that the value represented by the following formula (2) is 16 to 150. Formula (2): {[SiO２ ] / [ZrO ２ ]

[0046] The molecule in formula (2) is [SiO ２ ] means the content ratio of the main component constituting the glass network, and is calculated by subtracting the content ratio of the phase separation suppressing component ZrO ２ Dividing this by the content ratio of 16 or more gives an index of glass-forming ability. The above value is preferably 16 or more, more preferably 16 to 150, and even more preferably 20 to 120. Here, from the viewpoint of enhancing glass-forming ability, the above value is preferably 16 or more, more preferably 20 or more, even more preferably 25 or more, and even more preferably 30 or more. Furthermore, from the viewpoint of suppressing phase separation, the above value is preferably 150 or less, more preferably 120 or less, even more preferably 80 or less, and even more preferably 60 or less.

[0047] The composition of the crystallized glass according to this embodiment is SiO ２ , Al ２ O ３ and ZrO ２ Using the content ratio expressed in mole percentage, it is preferable that the value represented by the following formula (3) is 16 to 150. Formula (3): {([SiO ２ ]+[Al ２ O ３ ]) / [ZrO ２ ]

[0048] The molecule in the above formula (3) ([SiO ２ ]+[Al ２ O ３ ]) means the content ratio of the glass network constituent component, and this is calculated by subtracting the content ratio of the phase separation suppressing component ZrO ２ Dividing this by the content ratio of the sintered body gives an index of glass-forming ability. The above value is preferably 16 or more, more preferably 16 to 150, and even more preferably 20 to 140. From the viewpoint of enhancing glass-forming ability, the above value is preferably 16 or more, more preferably 20 or more, even more preferably 25 or more, and even more preferably 30 or more. From the viewpoint of suppressing phase separation, the above value is preferably 150 or less, more preferably 140 or less, even more preferably 80 or less, even more preferably 60 or less, and may be 50 or less, 45 or less, or 40 or less.

[0049] The composition of the crystallized glass according to this embodiment is ２ O, Al ２ O ３ and ZrO ２ Using the content ratio expressed in mole percentage, it is preferable that the value represented by the following formula (4) is 6 to 70. Formula (4): {([Li ２ O] + [Al ２ O ３ ]) / [ZrO ２ ]

[0050] The molecule in formula (4) ([Li ２ O] + [Al ２ O ３ ]) is the content ratio of the component that is an index of the depth of compressive stress layer (DOL) after chemical strengthening, and is used as an index of the surface compressive stress (CS) ２ Dividing by the content ratio of the compound (I) gives an index of chemical strengthening properties. The above value is preferably 6 or more, more preferably 6 to 70, and even more preferably 10 to 70. Here, from the viewpoint of increasing the compressive stress layer depth (DOL), the above value is preferably 6 or more, more preferably 10 or more, even more preferably 14 or more, and even more preferably 16 or more. Furthermore, from the viewpoint of increasing the surface compressive stress (CS), the above value is preferably 70 or less, more preferably 60 or less, and even more preferably 50 or less.

[0051] The composition of the crystallized glass according to this embodiment is ２ O, P ２ O ５ and ZrO ２ Using the content ratio expressed in mole percentage, it is preferable that the value represented by the following formula (5) is 3 to 10. Formula (5): {[Li ２ O] / ([P ２ O ５ ]+[ZrO ２ ])

[0052] The molecule in formula (5) [Li ２ O] is the content ratio of a component that indicates the ease of forming lithium disilicate, and P is an index of the ease of crystal precipitation. ２ O ５ and ZrO, which is an index of phase separation suppression.２ Dividing this by the sum of the content ratios of the above gives an index of the ease of forming lithium disilicate. The above value is preferably 3 or more, more preferably 3 to 10, and even more preferably 4 to 10. Here, from the viewpoint of increasing the crystallinity, the above value is preferably 3 or more, more preferably 4 or more, and even more preferably 6 or more. Furthermore, from the viewpoint of suppressing phase separation, the above value is preferably 10 or less, more preferably 9.5 or less, and even more preferably 9 or less.

[0053] In this embodiment, the composition of the amorphous phase preferably satisfies the following in terms of mole percentage based on oxides: SiO ２ 50-80%, Li ２ O 0.1-17%, Al ２ O ３ 0.1 to 20%, P ２ O ５ 0.1 to 15%, and ZrO ２ 0.1 to 20%.

[0054] In addition to the above, Na ２ O 0.1 to 20%, and K ２ It is preferable to further satisfy at least one of the following conditions: O 0.1 to 15%, and it is more preferable to satisfy both of the above conditions.

[0055] The content of the crystalline phase (degree of crystallization) in the crystallized glass according to this embodiment is 50 to 85% by mass, preferably 55 to 80% by mass, and more preferably 60 to 75% by mass. Conventional crystallized glass containing lithium disilicate crystals tends to become cloudier and whiter when the content of the crystalline phase is increased, and high transparency cannot be maintained. In contrast, the crystallized glass according to this embodiment can favorably control phase separation, and therefore can maintain high transparency even when the content of the crystalline phase is 50% by mass or more.

[0056] The content of the crystalline phase is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more from the viewpoint of realizing higher strength. Also, from the viewpoint of maintaining high transparency and three-dimensional moldability, the content of the crystalline phase is preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[0057] The crystalline phase is lithium disilicate (Li ２ Si ２ O ５ When the crystalline phase contains two or more types of crystals, the content of the crystalline phase means the total content of the two or more types of crystals.

[0058] The lithium disilicate crystals contained in the crystalline phase in this embodiment are high-strength crystals, and are therefore suitable for increasing the strength of crystallized glass. The content of lithium disilicate crystals in the crystalline phase is preferably 80% by mass or more, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass. From the viewpoint of achieving high strength, the content is preferably 80% by mass or more, more preferably 90% by mass or more. The content may also be 100% by mass, i.e., the crystalline phase may consist solely of lithium disilicate crystals. From the viewpoint of bendability, other crystals may also be contained, in which case the content of lithium disilicate crystals in the crystalline phase may be 95% by mass or less, or may be 85% by mass or less.

[0059] Examples of the other crystals include β-spodumene crystals (LiAlSi ２ O ６ ), petalite (LiAlSi ４ O １０ ), β-quartz (including bergerite) (Li ｘ Al ｘ Si ３－ｘ O ６ ), lithium metasilicate (Li ２ SiO ３ ), eucryptite (LiAlSiO ４ ), mullite (Al ４＋２ｘ Si ２－２ｘ O １０－ｘ , 0.2≦x≦0.5), lithium phosphate (Li ３ P.O. ４ However, the present invention is not limited to these and may be appropriately selected according to the desired properties.

[0060] For example, when it is desired to obtain a crystalline phase capable of ion exchange by chemical strengthening treatment, the crystals constituting the crystalline phase in the crystallized glass may be only lithium disilicate crystals, but may also contain β-spodumene crystals, petalite, β-quartz, lithium metasilicate, etc.

[0061] When it is desired to obtain crystallized glass having higher strength, the crystals constituting the above crystal phase may be only lithium disilicate crystals, but may also contain β-spodumene crystals, petalite, β-quartz, lithium metasilicate, mullite, etc.

[0062] When it is desired to achieve higher transparency, the crystals constituting the crystalline phase may be lithium disilicate crystals only, but may also contain β-quartz, lithium metasilicate, lithium phosphate, etc.

[0063] The crystallized glass according to this embodiment preferably has a half-width of 0.1 to 0.4 of the peak derived from lithium disilicate crystals observed in the range of 2θ = 23.5 to 25.5° in a powder X-ray diffraction pattern (XRD pattern) using Cu-Kα radiation. The half-width is related to the crystallinity and crystallite size, and the higher the crystallinity, the narrower the half-width, and the smaller the crystallite size, the narrower the half-width. In light of this tendency, the half-width is preferably 0.4 or less, more preferably 0.3 or less, even more preferably 0.25 or less, and preferably 0.1 or more.

[0064] The half width may be satisfied by a peak between 23.5 and 25.5 among peaks observed in the range of 2θ=10 to 80°.

[0065] In this embodiment, the average particle size of the crystals constituting the crystalline phase is preferably 20 to 200 nm. From the viewpoint of achieving higher strength, the average particle size is preferably 20 nm or more, more preferably 30 nm or more, even more preferably 40 nm or more, even more preferably 45 nm or more, and may be 50 nm or more, 55 nm or more, 60 nm or more, 70 nm or more, more than 80 nm, or even 90 nm or more. From the viewpoint of achieving higher transparency, the average particle size is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less. The average particle size can be measured by observation with a scanning electron microscope (SEM). The average particle size can also be adjusted by adjusting the heat treatment conditions.

[0066] The Young's modulus of the crystallized glass according to this embodiment is preferably 95 to 120 GPa. From the viewpoint of high strength, the Young's modulus is preferably 95 GPa or more, more preferably 98 GPa or more, and even more preferably 100 GPa or more. From the viewpoint of high strength, the higher the Young's modulus, the more preferable it is, and although there are no particular limitations, it may be, for example, 120 GPa or less. The Young's modulus in this specification can be measured by an ultrasonic method.

[0067] The fracture toughness value K of the crystallized glass according to this embodiment ＩＣ is 1.00 MPa m １／２ or more is preferable, and 1.00 to 1.60 MPa m １／２ Here, from the viewpoint of high strength, the fracture toughness value K ＩＣ is 1.00 MPa m １／２ More preferably, 1.20 MPa m １／２ More preferably, 1.30 MPa m １／２ The upper limit is not particularly limited, but is, for example, 1.60 MPa m １／２ The fracture toughness value K ＩＣ can be adjusted by the crystal species, the degree of crystallization, and the glass composition. ＩＣcan be measured by the pre-crack introduction fracture test method (SEPB method: Single-Edge-Precracked-Beam method) specified in JIS R1607:2015.

[0068] The haze value of the crystallized glass according to this embodiment is preferably 0.02 to 1.00%, more preferably 0.02 to 0.80%. From the viewpoint of visibility when the crystallized glass is used as a cover glass, particularly a three-dimensionally shaped cover glass, the haze value is preferably 1.00% or less, more preferably 0.80% or less, even more preferably 0.40% or less, even more preferably 0.30% or less, even more preferably 0.20% or less, and particularly preferably 0.15% or less. The smaller the haze value, the better, but it is usually 0.02% or more. The haze value can be adjusted by the crystal species, degree of crystallization, and glass composition. The haze value in this specification refers to the value measured using illuminant C in accordance with JIS K 7136:2000, converted into a 0.7 mm thickness of the crystallized glass. Furthermore, when the actual thickness of the crystallized glass is not 0.7 mm, the haze value can be converted into a 0.7 mm thickness based on the measured value using the Lambert-Beer law. Furthermore, when the plate thickness t is greater than 0.7 mm, the plate thickness of the crystallized glass may be adjusted to 0.7 mm by polishing, etching, or the like, before measurement.

[0069] Chemically strengthened glass according to this embodiment has a compressive stress layer formed by ion exchange on the surface of the crystallized glass. Here, the crystallized glass may be the crystallized glass described in the above section, and preferred aspects other than strength are also the same.

[0070] That is, the chemically strengthened glass according to this embodiment has, in terms of mole percentage based on oxides, SiO ２ 55-70%, Li ２ O 15-27.0%, Al ２ O ３ 0.1-2.6%, P ２ O ５ 0.5 to 5%, and ZrO ２The content of the crystalline phase in the chemically strengthened glass is 50 to 85 mass %, and the crystalline phase satisfies the following: Li 0.5 to 2.6%. ２ Si ２ O ５ Li in the crystalline phase ２ Si ２ O ５ The content of crystals is 80% by mass or more.

[0071] In this specification, the term "ion exchange" is synonymous with chemical strengthening, and refers to the ion exchange of specific ions in the surface layer of crystallized glass with other ions having a larger ionic radius. As a result, a compressive stress layer is formed on the surface layer of the crystallized glass. Crystallized glass that has undergone such chemical strengthening is referred to as "chemically strengthened glass." The matrix composition of chemically strengthened glass is considered to be the same as the composition of the crystallized glass before the chemical strengthening treatment, and except in cases where extreme ion exchange treatment has been performed, the composition of the portion deeper than the compressive stress layer depth (DOL) of the chemically strengthened glass is considered to be the same as the matrix composition of the chemically strengthened glass. In other words, the composition of the center of the plate thickness of chemically strengthened glass is the same as the matrix composition of the chemically strengthened glass.

[0072] The chemically strengthened glass according to this embodiment is preferably a chemically strengthened glass in which Li ions in the glass are ion-exchanged with Na ions. ２ The content of O is determined based on the composition of the glass-ceramics before chemical strengthening, i.e., the Na content in the base composition of the chemically strengthened glass. ２ The content of Na is preferably higher than that of O, and the difference is more preferably 1 mol % or more. The difference is further preferably 5 mol % or more, and even more preferably 10 mol % or more. ２ The upper limit of the difference in the O content is not particularly limited, but is, for example, 30 mol % or less.

[0073] The chemically strengthened glass according to this embodiment does not show significant changes in the overall composition, crystallinity, and physical properties other than strength compared to the crystallized glass before chemical strengthening treatment, and can be considered the same. However, the peak position in the X-ray diffraction (XRD) pattern of the surface of the crystallized glass shifts from before the chemical strengthening treatment. In addition, the composition, crystalline structure, and crystallinity near the surface of the chemically strengthened glass may differ.

[0074] In the XRD pattern, the peak position derived from lithium disilicate crystals in the surface X-ray diffraction pattern using Cu-Kα radiation preferably shifts before and after ion exchange, more preferably to a lower angle. The peak shift means that ions in the crystals are also exchanged. The XRD measurement is performed on the surface of the crystallized glass before and after chemical strengthening treatment using CuKα radiation at a 2θ range of 10° to 80°. Specifically, among the peaks derived from lithium disilicate crystals in the chemically strengthened glass, the peak shift from the peak before ion exchange is preferably 0.02° or more, more preferably 0.02 to 0.10°. Here, the peak shift is preferably 0.02° or more, more preferably 0.03° or more. Furthermore, from the viewpoint of maintaining the crystal structure, the peak shift is preferably 0.10° or less, more preferably 0.08° or less.

[0075] The physical properties related to the strength include surface compressive stress (CS), depth of compressive stress layer (DOL), internal tensile stress (CT), ST limit, fracture toughness value, Young's modulus, Vickers hardness, etc. On the other hand, physical properties other than strength include haze value, average transmittance, average thermal expansion coefficient, etc.

[0076] The surface compressive stress (CS) of the chemically strengthened glass according to this embodiment is preferably 300 MPa or more, more preferably 500 MPa or more, and even more preferably 600 MPa or more, from the viewpoint of preventing cracking due to deformation such as bending. The upper limit of the surface compressive stress is not particularly limited, but is, for example, 1400 MPa or less. The value of the surface compressive stress can be adjusted, for example, by the Na concentration in the molten salt used in the chemical strengthening treatment, the chemical strengthening treatment conditions, the Li concentration in the glass composition, etc. In this specification, the surface compressive stress (CS) can be measured by slicing a cross section of the chemically strengthened glass and analyzing the sliced ​​sample with a birefringence imaging system. An example of a birefringence imaging system is the Abrio-IM birefringence imaging system manufactured by Tokyo Instruments Inc. Surface compressive stress can also be measured using scattered light photoelasticity. In this method, light is incident on the surface of the chemically strengthened glass, and the polarization of the scattered light is analyzed to measure CS. An example of a stress measuring instrument that utilizes scattered light photoelasticity is the scattered light photoelastic stress meter SLP-1000 manufactured by Orihara Seisakusho.

[0077] The compressive stress layer depth (DOL) of the chemically strengthened glass according to this embodiment is preferably 50 μm or more, more preferably 60 μm or more, and even more preferably 70 μm or more, from the viewpoint of preventing cracks when scratches occur on the surface of the chemically strengthened glass. The upper limit of the compressive stress layer depth is not particularly limited, but is, for example, 200 μm or less. The value of the compressive stress layer depth can be adjusted, for example, by the time for performing the chemical strengthening treatment. In this specification, the compressive stress layer depth (DOL) is the depth at which the surface compressive stress (CS) becomes zero.

[0078] The chemically strengthened glass according to this embodiment more preferably satisfies both a surface compressive stress of 300 MPa or more and a compressive stress layer depth of 50 μm or more.

[0079] The Vickers hardness of the crystallized glass according to this embodiment that has been subjected to chemical strengthening treatment is preferably 680 GPa or more, more preferably 720 GPa or more, and even more preferably 750 GPa or more, from the viewpoint of scratch resistance. The higher the Vickers hardness, the better, but it is usually 1200 GPa or less. In this specification, the Vickers hardness refers to the Vickers hardness (HV0.1) specified in JIS R1610:2003.

[0080] <<Glass>> The glass according to this embodiment has a composition expressed in mole percentage based on oxides that satisfies the following: SiO ２ 55-70%, Li ２ O 15-27.0%, Al ２ O ３ 0.1-2.6%, P ２ O ５ 0.5 to 5%, and ZrO ２ 0.5 to 2.6%.

[0081] In addition to the above, the glass composition is Na ２ O 0.1 to 5%, and K ２ It is preferable to further satisfy at least one of the following conditions: O 0.1 to 3%, and it is more preferable to satisfy both of the above conditions.

[0082] In addition, the glass according to this embodiment contains SiO ２ , Al ２ O ３ , Li ２ O, and ZrO ２ Using the content ratio expressed in mole percentage, the formula (1)": {([SiO ２ ]+[Al ２ O ３ ]+[Li ２ O]) / [ZrO ２ ]} is preferably 18 or more, and may be 20 to 500. From the viewpoint of increasing the crystallinity, the value is preferably 18 or more, more preferably 20 or more, even more preferably 25 or more, and even more preferably 30 or more. Furthermore, from the viewpoint of suppressing devitrification, the value is preferably 500 or less, more preferably 400 or less, even more preferably 300 or less, and even more preferably 200 or less.

[0083] The glass according to this embodiment is the glass before crystallization, which is suitable for obtaining the crystallized glass described in the above "crystallized glass". Therefore, the suitable range of each component of the glass is the same as the suitable range of each component in the above "crystallized glass".

[0084] The glass is preferably glass-ceramics in which a crystalline phase containing lithium disilicate crystals is formed by heat treatment, and more preferably glass-ceramics in which the content of lithium disilicate crystals in the crystalline phase is 80% by mass or more and the haze value is 1.00% or less when the crystallinity is increased to 50% by mass or more by heat treatment.

[0085] <<Three-dimensional Shape Cover Glass>> The three-dimensional shape cover glass according to this embodiment may be made of crystallized glass having a three-dimensional shape with a curved surface portion forming a three-dimensional curved surface, or may be made of chemically strengthened crystallized glass having a three-dimensional shape with a curved surface portion forming a three-dimensional curved surface. Here, the crystallized glass may be one described in the above section <<Crystalline Glass>>, and preferred embodiments are the same. Furthermore, the chemically strengthened crystallized glass may be one described in the above section <<Chemically Strengthened Glass>>, and preferred embodiments are the same.

[0086] When crystallized glass or chemically strengthened glass is bent into a three-dimensional shape to form a three-dimensional cover glass, no significant changes are observed in the composition, crystallinity, or physical properties of the crystallized glass or chemically strengthened glass as a whole, and the resulting glass can be considered to be the same as the flat crystallized glass or chemically strengthened glass before three-dimensional forming.

[0087] The three-dimensional cover glass according to the present embodiment can have any conventionally known three-dimensional shape. Here, the three-dimensional shape refers to a shape obtained by bending a flat plate. The three-dimensional shape is not limited to a shape with a uniform thickness overall, but may also have portions with varying thicknesses.

[0088] The three-dimensional shape may be, for example, a shape in which the central portion is flat and the end portions are concave or convex. Alternatively, the central portion may not be flat, and the entire crystallized glass or the entire chemically strengthened glass may be curved, or may be a shape composed of multiple R shapes.

[0089] <<Uses>> The crystallized glass, chemically strengthened glass, and three-dimensionally shaped cover glass according to the present embodiment are all useful as cover glass for electronic devices such as mobile devices such as mobile phones and smartphones. They are also useful as cover glass for non-portable electronic devices such as televisions, personal computers, and touch panels, as well as elevator walls and wall surfaces (full-surface displays) of buildings such as houses and buildings. They are also useful as building materials such as window glass, tabletops, interiors of automobiles and airplanes, and cover glass for these, as well as for curved housings.

[0090] <<Method for Manufacturing Crystallized Glass, Chemically Strengthened Glass, and Three-Dimensional Shape Cover Glass>> The crystallized glass according to this embodiment can be manufactured by heat-treating amorphous glass to crystallize it. That is, the method for manufacturing crystallized glass according to this embodiment includes the following steps 1 and 2. Furthermore, the method for manufacturing chemically strengthened glass according to this embodiment includes the following steps 1 to 3. Furthermore, the method for manufacturing a three-dimensional shape cover glass according to this embodiment includes the following steps 1 to 4, or the following steps 1, 2, and 4.

[0091] Step 1: A step of producing amorphous glass. Step 2: A step of crystallizing the amorphous glass obtained in step 1 to obtain crystallized glass. Step 3: A step of chemically strengthening the crystallized glass obtained in step 2 to obtain chemically strengthened glass. Step 4: A step of providing a three-dimensional curved surface to the crystallized glass obtained in step 2 or the chemically strengthened glass obtained in step 3 to obtain a three-dimensional shaped cover glass.

[0092] Each step will be described below.

[0093] <Step 1> Step 1 is a step of producing amorphous glass, and a conventionally known method can be used as the specific method. That is, when obtaining plate-shaped amorphous glass, for example, glass raw materials are blended to a desired composition and heated and melted in a glass melting furnace. The molten glass is then homogenized by bubbling, stirring, adding a fining agent, etc., and formed into a glass plate of a predetermined thickness by a known forming method, followed by annealing. Alternatively, the molten glass may be formed into a plate by forming it into a block, annealing it, and then cutting it. Examples of forming methods for plate-shaped glass include the float method, the press method, the fusion method, and the downdraw method. Examples of annealing methods include a method in which the glass is cooled to room temperature at a rate of 0.1 to 2°C / min. The annealing may involve holding the glass at a specific temperature for a specific period of time and then cooling it to room temperature. Specifically, for example, the glass may be held at 420 to 550°C for 10 to 180 minutes and then cooled to room temperature at a rate of 0.1 to 2°C / min.

[0094] Furthermore, the above-mentioned desired composition is the same as the preferred embodiment described in the above "Ceramics", and in order to obtain such crystallized glass, it is preferable to obtain the amorphous glass described in the above "Glass".

[0095] <Step 2> Step 2 is a step of obtaining crystallized glass by crystallizing the amorphous glass obtained in step 1. This results in crystallized glass containing a crystalline phase of lithium disilicate crystals.

[0096] The heat treatment for crystallization is not particularly limited as long as it produces the desired crystals, but may be, for example, a two-stage heat treatment in which the temperature is raised from room temperature to a first treatment temperature and maintained for a certain period of time, and then maintained at a second treatment temperature higher than the first treatment temperature for a certain period of time. After the two-stage heat treatment, a three-stage heat treatment in which the temperature is maintained at a third treatment temperature for a certain period of time may be performed. Alternatively, a one-stage heat treatment in which the temperature is maintained at a specific treatment temperature and then cooled to room temperature may be performed.

[0097] In the case of a two-stage heat treatment, the first treatment temperature is preferably in a temperature range where the crystal nucleation rate is high for the glass composition, and the second treatment temperature is preferably in a temperature range where the crystal growth rate is high for the glass composition.

[0098] In the case of a three-stage heat treatment, it is preferable that the first and second treatment temperatures are temperatures at which the crystal nucleation rate increases, and the third treatment temperature is a temperature at which the crystal growth rate increases. Alternatively, the first treatment temperature may be a temperature at which the crystal nucleation rate increases, and the second and third treatment temperatures may be temperatures at which the crystal growth rate increases.

[0099] In the two-stage heat treatment and the three-stage heat treatment, the holding time at the first treatment temperature is preferably long enough to generate a sufficient number of crystal nuclei. The generation of a large number of crystal nuclei reduces the size of each crystal, resulting in a highly transparent crystallized glass.

[0100] More specifically, in the case of a two-stage treatment, for example, the first treatment temperature is held at 500°C to 700°C for 1 hour to 6 hours, and then the second treatment temperature is held at 600°C to 800°C for 1 hour to 6 hours.

[0101] More specifically, in the case of a three-stage treatment, for example, after holding at a first treatment temperature of 450°C to 600°C for 1 hour to 6 hours, for example, at a second treatment temperature of 500°C to 650°C for 1 hour to 6 hours, and further, for example, at a third treatment temperature of 600°C to 800°C for 1 hour to 6 hours.

[0102] More specifically, in the case of a one-stage treatment, the temperature may be maintained at 500° C. to 800° C. for 1 hour to 6 hours.

[0103] The crystallized glass obtained in step 2 may be ground and polished as necessary. Furthermore, when the crystallized glass obtained is cut to a predetermined shape and size or chamfered, it is preferable to perform the cutting or chamfering before performing the chemical strengthening treatment in the next step 3. This allows a compressive stress layer to be formed on the end surfaces, such as the cut surface and the chamfered surface, by the subsequent chemical strengthening treatment.

[0104] <Step 3> Step 3 is a step of obtaining chemically strengthened glass by performing a chemical strengthening treatment on the crystallized glass obtained in step 2. The chemical strengthening treatment is a treatment in which the glass is brought into contact with a metal salt (e.g., potassium nitrate) containing a metal ion with a large ionic radius (typically, Na ion or K ion) by, for example, immersing the glass in a melt of the metal salt, thereby replacing the metal ion with a small ionic radius (typically, Li ion or Na ion) with a metal ion with a large ionic radius (typically, Na ion or K ion for Li ion, and K ion for Na ion).

[0105] To increase the speed of chemical strengthening, it is preferable to use "Li-Na exchange," which exchanges Li ions in the glass with Na ions. Here, the crystallized glass in this embodiment contains lithium disilicate crystals and optionally other crystals, and a compressive stress layer is formed not only in the amorphous phase but also by converting Li constituting these crystals to Na.

[0106] In order to form a larger compressive stress by ion exchange, it is preferable to use "Na-K exchange" in which Na ions in the glass are exchanged with K ions.

[0107] Examples of molten salts for chemical strengthening include nitrates, sulfates, carbonates, and chlorides. Examples of nitrates include lithium nitrate, sodium nitrate, potassium nitrate, cesium nitrate, and silver nitrate. Examples of sulfates include lithium sulfate, sodium sulfate, potassium sulfate, cesium sulfate, and silver sulfate. Examples of carbonates include lithium carbonate, sodium carbonate, and potassium carbonate. Examples of chlorides include lithium chloride, sodium chloride, potassium chloride, cesium chloride, and silver chloride. These molten salts may be used alone or in combination.

[0108] The conditions for the chemical strengthening treatment, such as time and temperature, can be selected taking into consideration the glass composition, the type of molten salt, etc. For example, the crystallized glass obtained in step 2 can be chemically strengthened at preferably 500°C or less for preferably 20 hours or less. Alternatively, two or more stages of chemical strengthening treatment may be performed.

[0109] <Step 4> Step 4 is a step of imparting a three-dimensional curved surface to the crystallized glass obtained in step 2 or the chemically strengthened glass obtained in step 3 to obtain a three-dimensionally shaped cover glass.

[0110] To provide a curved surface, a conventionally known bending method can be used. Examples of the bending method include gravity forming, vacuum forming, and press forming. Two or more bending methods may also be used in combination.

[0111] The gravity forming method is a method in which crystallized glass or chemically strengthened glass is placed on a forming mold, and then the crystallized glass or chemically strengthened glass is heated and conformed to the forming mold by gravity, thereby bending and forming it into a predetermined shape.

[0112] In vacuum forming, crystallized glass or chemically strengthened glass is placed on a forming mold, the periphery of the crystallized glass or chemically strengthened glass is sealed, and then the space between the forming mold and the crystallized glass or chemically strengthened glass is reduced in pressure, and a pressure difference is applied to the front and back surfaces of the crystallized glass or chemically strengthened glass to bend and form it. At this time, pressure may be applied to the top surface of the crystallized glass or chemically strengthened glass as an auxiliary step.

[0113] In the press molding method, crystallized glass or chemically strengthened glass is placed between molds (lower and upper molds), heated, and pressed between the upper and lower molds to bend and mold it into a predetermined shape. In either molding method, the crystallized glass or chemically strengthened glass is deformed by applying force while heated.

[0114] The bending (hot bending) temperature is, for example, 700°C to 1100°C, and preferably 750°C to 1050°C.

[0115] Furthermore, the difference between the maximum temperature of the crystallization treatment in step 2 and the heat bending temperature in step 4 is preferably 10 to 120°C, more preferably 10 to 100°C, even more preferably 30 to 90°C, and even more preferably 30 to 60°C. Here, if the heat bending temperature is higher than the maximum temperature of the crystallization treatment in step 2, thermal deformation easily occurs, so from the viewpoint of achieving high dimensional accuracy, the difference between the maximum temperature of the crystallization treatment and the heat bending temperature is preferably 10°C or more, more preferably 30°C or more. Furthermore, from the viewpoint of suppressing a decrease in light transmittance due to bending, the temperature difference is preferably 120°C or less, more preferably 100°C or less, even more preferably 90°C or less, and even more preferably 60°C or less.

[0116] The reduction in the average transmittance of light having a wavelength of 380 to 780 nm of the crystallized glass or chemically strengthened glass due to bending is preferably 3% or less, more preferably 2% or less, even more preferably 1.5% or less, and even more preferably 1% or less, and the smaller the better.

[0117] Alternatively, the crystallized glass obtained in step 2 may be subjected to step 4 to obtain a three-dimensional cover glass, and then subjected to chemical strengthening treatment in step 3 to obtain chemically strengthened glass.

[0118] The present invention will be described below with reference to examples, but is not limited thereto. Examples 1 to 11 are working examples, and Examples 12 to 15 are comparative examples.

[0119] Examples 1 to 15 Glass raw materials were blended to obtain the glass compositions shown in Table 1 or Table 2 in terms of oxide-based mole percent, and weighed to obtain 600 g of glass. The mixed glass raw materials were then placed in a platinum crucible and placed in an electric furnace at 1550°C, where they were melted for approximately 5 hours, degassed, and homogenized. The resulting molten glass was poured into a mold, held at 470°C for 1 hour, and then cooled to room temperature at a rate of 0.5°C / min to obtain a glass block. Note that blanks in the glass composition columns in Table 1 or Table 2 indicate that no additives were added.

[0120] The obtained glass blocks were each processed into a plate of 50 mm × 50 mm × 1.5 mm and subjected to a two-stage crystallization treatment. Specifically, the first treatment and the second treatment were performed at the temperature and holding time shown in the "Heat Treatment Conditions" in Table 1 or Table 2. For Example 12, a third treatment was also performed. Then, the blocks were cooled to room temperature to obtain crystallized glass.

[0121] <Evaluation> <X-ray diffraction: precipitated crystals> Powder X-ray diffraction was measured for the crystallized glass under the following conditions, and the crystallinity, precipitated crystals and their content ratio, and average crystal particle size were determined by Rietveld analysis. ２ Si ２ O ５ ) crystals, a peak was observed at 2θ = 23.8° in the range of 2θ = 23.5 to 25.5°, and the half-width of this peak was also determined. The results are shown in Table 1 or Table 2. Blanks for the average particle size and half-width mean that the data has not been analyzed. Measuring device: SmartLab manufactured by Rigaku Corporation X-ray used: Cu-Kα ray Measuring range: 2θ = 10° to 80° Speed: 10° / min Step: 0.02°

[0122] <Composition> The composition of the obtained crystallized glass was analyzed, and it was confirmed that there was no significant change from the glass composition before crystallization, and that it was the same as the glass composition shown in Table 1 or Table 2. Therefore, in Tables 1 and 2, the composition is shown as "(crystallized) glass". In addition, the composition of the amorphous phase of the crystallized glass was determined from the composition of the crystallized glass, the degree of crystallization, and the precipitated crystalline phase and its content ratio. The results are shown in Table 1 or Table 2.

[0123] <Haze Value> The haze value of the crystallized glass was measured using a haze meter (HZ-V3 manufactured by Suga Test Instruments) under Illuminant C and converted into a haze value at a thickness of 0.7 mm. The results are shown in Table 1 or Table 2.

[0124] <Young's Modulus> The Young's modulus of the crystallized glass was measured by an ultrasonic method using an ultrasonic thickness gauge (manufactured by Olympus Corporation, trade name 38DL). The results are shown in Table 1 or Table 2.

[0125] Fracture toughness value K ＩＣ> Fracture toughness value K of crystallized glass ＩＣ was measured using a strength testing machine (Shimadzu Corporation, Autograph AGS-X) by the pre-crack introduction fracture test method (SEPB method: Single-Edge-Precracked-Beam method) specified in JIS R1607:2015. The results are shown in Table 1 or Table 2.

[0126]

[0127]

[0128] From the above results, the crystallized glass according to this embodiment can realize a crystalline phase containing 80% or more lithium disilicate crystals and having a crystallinity of 50 to 85% by mass. This allows for both high transparency and high crystallinity. Although the crystallized glass of Examples 1 to 11 above was not chemically strengthened, the lithium disilicate crystals are crystals that can undergo ion exchange between Li ions in the crystals and Na ions in the molten salt through chemical strengthening. Therefore, it can be said to have excellent chemical strengthening processability, and further strengthening through ion exchange is possible. Furthermore, since the crystallized glass or chemically strengthened glass according to this embodiment contains a low proportion of crystals other than lithium disilicate crystals, it can achieve both a high Young's modulus and high three-dimensional formability.

[0129] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese patent applications filed on June 7, 2024 (Patent Application No. 2024-092882) and March 31, 2025 (Patent Application No. 2025-058528), the contents of which are incorporated herein by reference.

Claims

1. A crystallized glass having a crystalline phase and an amorphous phase, wherein the composition of the crystallized glass is expressed in mole percentage based on oxides: SiO ２ 55-70%, Li ２ O 15-27.0%, Al ２ O ３ 0.1-2.6%, P ２ O ５ 0.5 to 5%, and ZrO ２ 0.5 to 2.6%, the content of the crystalline phase in the crystallized glass is 50 to 85 mass%, and the crystalline phase is Li ２ Si ２ O ５ The Li in the crystalline phase ２ Si ２ O ５ The crystallized glass has a crystal content of 80% by mass or more.

2. SiO ２ , Al ２ O ３ , Li ２ O, and ZrO ２ Using the content ratio expressed in mole percentage, the formula (1): {([SiO ２ ]+[Al ２ O ３ ]+[Li ２ O]) / [ZrO ２ 2. The crystallized glass according to claim 1, wherein the value represented by {overscore (R)} is 18 or more.

3. The composition of the crystallized glass is expressed in mole percentage based on oxides: Na ２ O 0.1 to 5%, and K ２ 2. The crystallized glass according to claim 1, further comprising 0.1 to 3% O.

4. The Li is observed in the range of 2θ=23.5 to 25.5° in a powder X-ray diffraction pattern using Cu-Kα radiation. ２ Si ２ O ５ 2. The crystallized glass according to claim 1, wherein the half-value width of the peak derived from the crystal is 0.1 to 0.

4.

5. The composition of the amorphous phase is expressed in mole percentage on an oxide basis as follows: SiO ２ 50-80%, Li ２ O 0.1-17%, Al ２ O ３ 0.1 to 20%, P ２ O ５ 0.1 to 15%, and ZrO ２ 2. The crystallized glass according to claim 1, wherein the content of the crystallized glass satisfies 0.1 to 20%.

6. The crystallized glass according to claim 1, having a Young's modulus of 95 to 120 GPa.

7. The crystallized glass according to claim 1, having a haze value of 0.02 to 1.00%.

8. Fracture toughness value is 1.00 MPa m １／２ The chemically strengthened glass according to claim 1, wherein 9. The crystallized glass according to claim 1, wherein the average grain size of the crystals constituting the crystalline phase is 20 to 200 nm.

10. Chemically strengthened glass having a compressive stress layer formed by ion exchange on the surface of the crystallized glass according to any one of claims 1 to 9.

11. Na in the surface layer ２ The content of O is determined by the ratio of Na in the composition of the crystallized glass. ２ The chemically strengthened glass according to claim 10, wherein the content ratio of O is higher than the content ratio of O, and the difference is 1 mol% or more.

12. The chemically strengthened glass according to claim 10, wherein the surface compressive stress is 300 MPa or more and the compressive stress layer depth is 50 μm or more.

13. In the X-ray diffraction pattern of the surface using Cu-Kα radiation, ２ Si ２ O ５ The chemically strengthened glass according to claim 10, wherein, among peaks derived from crystals, there is one or more peaks having a peak shift amount of 0.02 ° or more from the peak before the ion exchange.

14. The composition in mole percentage based on oxide is SiO ２ 55-70%, Li ２ O 15-27.0%, Al ２ O ３ 0.1-2.6%, P ２ O ５ 0.5 to 5%, and ZrO ２ Glass that satisfies 0.5 to 2.6%.

15. Li by heat treatment ２ Si ２ O ５ 15. The glass of claim 14, wherein a crystalline phase comprising crystals is formed.

16. SiO ２ , Al ２ O ３ , Li ２ O, and ZrO ２ Using the content ratio expressed in mole percentage, the formula (1)": {([SiO ２ ]+[Al ２ O ３ ]+[Li ２ O]) / [ZrO ２ ]} is 18 or more.

17. The above composition in mole percentage on an oxide basis is: Na ２ O 0.1 to 5%, and K ２ The glass according to claim 14 or 15, further comprising 0.1 to 3% O.

18. A three-dimensional cover glass comprising the chemically strengthened glass according to claim 10, wherein the chemically strengthened glass has a three-dimensional shape having a curved surface portion that forms a three-dimensional curved surface.

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