Glass-ceramics

Abstract

The purpose of the present invention is to provide a glass in which crystals in the glass easily disappear at re-melting and thus devitrification hardly occurs. The present invention pertains to a crystallized glass that has a lithium aluminosilicate composition and contains crystals and residual glass, wherein the composition of the residual glass is within a definite range and parameter V is from -600 to 720 inclusive, said parameter V being calculated in accordance with the following equation with the use of the contents, in terms of mol% of oxides, of the following components in the residual glass: SiO2, Al2O3, P2O5, MgO, CaO, SrO, Li2O, Na2O, K2O, TiO2 and ZrO2. V=49.589×[SiO2]+61.806×[Al2O3]+45.456×[P2O5]+41.151×[MgO]+110.26×[CaO]+50.263×[SrO]+55.693×[Li2O]+3.598×[Na2O]+9.503×[K2O]+6.83×[TiO2]-2.885×[ZrO2]-3746.99

Description

[Technical Field]

[0001] The present invention relates to glass-ceramics that exhibit excellent crystal disappearance and reprecipitation properties when remelted. [Background technology]

[0002] Thin, strong chemically strengthened glass is used for the cover glass of mobile phones, smartphones, etc., and crystallized glass is sometimes used as the glass for chemical strengthening because it is transparent and scratch-resistant.

[0003] Glass-ceramics are formed by heating amorphous glass (mother glass) to precipitate crystals inside, and contain precipitated crystals and residual glass. Various compositions of glass-ceramics are known. Among these, glass-ceramics containing lithium aluminosilicate (LAS) crystals can be chemically strengthened to achieve extremely high strength (see, for example, Patent Document 1).

[0004] The general manufacturing process for crystallized glass includes the steps of mixing the materials, melting, forming, cutting after slow cooling, crystallization in which the glass is crystallized by heat treatment, polishing, and then processing steps such as bending and chemical strengthening. If defects such as chipping or optical inhomogeneity occur during the crystallization process, the glass will not flow easily to the next step, leading to material loss and a reduced yield rate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 022035 Summary of the Invention [Problem to be solved by the invention]

[0006] After the melting process of remelting the crystallized glass containing defects, the crystallized glass is again subjected to the forming process, the cutting process, and the crystallization process, thereby preventing the yield reduction caused by the defects occurring in the glass during the crystallization process.However, if crystals remain when the crystallized glass containing defects is remelted, the remaining crystals become nuclei and cause devitrification, which further reduces the yield.In addition, depending on the composition of the glass, there is also the problem that other crystals are generated in the glass as devitrification during remelting.

[0007] Therefore, an object of the present invention is to provide glass in which crystals are likely to disappear when remelted and devitrification is unlikely to occur. [Means for solving the problem]

[0008] The present inventors have conducted research focusing on the residual glass composition of crystallized glass, and as a result have found that the above problems can be solved by setting the residual glass composition within a specific range, thereby achieving the present invention.

[0009] The present invention provides a glass-ceramic having a lithium aluminosilicate composition and containing crystals and residual glass, the composition of which is expressed in mole percent on an oxide basis. SiO2 25-70% Al2O3 3-35% Li2O 0.1~20% Na2O 0.1~20% K2O 0~10% The present invention relates to glass-ceramics in which the content of ZrO2 is 1 to 15%, and the parameter V calculated according to the following formula using the contents of the components SiO2, Al2O3, P2O5, MgO, CaO, SrO, Li2O, Na2O, K2O, TiO2, and ZrO2, [SiO2], [Al2O3], [P2O5], [MgO], [CaO], [SrO], [Li2O], [Na2O], [K2O], [TiO2], and [ZrO2], expressed as mole percent on an oxide basis in the residual glass, is -600 or more and 720 or less. V=49.589×[SiO2]+61.806×[Al2O3]+45.456×[P2O5]+41.151×[MgO]+110.26×[CaO]+50.263 ×[SrO]+55.693×[Li2O]+3.598×[Na2O]+9.503×[K2O]+6.83×[TiO2]-2.885×[ZrO2]-3746.99

[0010] The present invention provides a glass-ceramic having a lithium aluminosilicate composition and containing crystals and residual glass, the composition of which is expressed in mole percent on an oxide basis. SiO2 25-70% Al2O3 3-35% Li2O 0.1~20% Na2O 0.1~20% K2O 0~10% The present invention relates to glass-ceramics containing 1 to 15% ZrO2, and wherein the value calculated from the formula [Al2O3] / ([SiO2]+[Al2O3]) using the respective component contents [SiO2] and [Al2O3] of SiO2 and Al2O3 in the residual glass, expressed as mole percent on an oxide basis, is 0.07 or more and 0.5 or less.

[0011] The present invention provides a glass-ceramic having a lithium aluminosilicate composition and containing crystals and residual glass, the composition of which is expressed in mole percent on an oxide basis. SiO2 25-70% Al2O3 3-35% Li2O 0.1~20% Na2O 0.1~20% K2O 0~10% The present invention relates to glass-ceramics containing 1-15% ZrO2, and wherein the value calculated by the formula [ΣR+] / ([SiO2]+[Al2O3]) using the total content of alkali components [ΣR+] and the contents of SiO2 and Al2O3, [SiO2] and [Al2O3], expressed in mole percent on an oxide basis in the residual glass, is 0.05 or more and 0.42 or less.

[0012] The present invention provides a glass-ceramic having a lithium aluminosilicate composition and containing crystals and residual glass, the composition of which is expressed in mole percent on an oxide basis. SiO2 25-70% Al2O3 3-35% Li2O 0.1~20% Na2O 0.1~20% K2O 0~10% The present invention relates to glass-ceramics in which the content of ZrO2 is 1 to 15%, and the parameter G calculated according to the following formula using the contents of the components SiO2, Al2O3, MgO, Li2O, Na2O, K2O, and ZrO2, [SiO2], [Al2O3], [MgO], [Li2O], [Na2O], [K2O], and [ZrO2], expressed as mole percent on an oxide basis in the residual glass, is -13,000 or more and less than 1,000. G=-600.1×[SiO2]-368.987×[Al2O3]-659.214×[MgO]-361.434×[Li2O]-1184.84×[Na2O]-1524.6×[K2O]-1516.47×[ZrO2]+60922.7

[0013] The present invention provides a glass-ceramic having a lithium aluminosilicate composition and containing crystals and residual glass, the composition of which is expressed in mole percent on an oxide basis. SiO2 25-70% Al2O3 3-35% Li2O 0.1~20% Na2O 0.1~20% K2O 0~10% The present invention relates to glass-ceramics in which the content of ZrO2 is 1 to 15%, and the parameter D calculated according to the following formula using the contents of the components SiO2, Al2O3, MgO, P2O5, CaO, Li2O, Na2O, K2O, TiO2, and ZrO2, [SiO2], [Al2O3], [MgO], [P2O5], [CaO], [Li2O], [Na2O], [K2O], [TiO2], and [ZrO2], expressed as mole percent on an oxide basis in the residual glass composition, is 1400 or more and 2500 or less. D=-72.3739×[SiO2]-24.174×[Al2O3]-78.0127×[P2O5]-80.0648×[MgO]-156.732×[CaO]-61 .4172×[Li2O]-99.7426×[Na2O]-106.162×[K2O]-199.391×[TiO2]+7.09771×[ZrO2]+7907.11

[0014] The present invention provides a glass-ceramic having a lithium aluminosilicate composition and containing crystals and residual glass, the composition of which is expressed in mole percent on an oxide basis. SiO2 25-70% Al2O3 3-35% Li2O 0.1~20% Na2O 0.1~20% K2O 0~10% The present invention relates to glass-ceramics in which the content of each of the components SiO2, Al2O3, P2O5, MgO, CaO, SrO, Li2O, Na2O, K2O, TiO2, and ZrO2 in the residual glass composition, expressed as mole % based on oxides, is 1 to 15%, and the sum (V+G) of parameter V and parameter G calculated according to the following formula using the contents [SiO2], [Al2O3], [P2O5], [MgO], [CaO], [SrO], [Li2O], [Na2O], [K2O], [TiO2], and [ZrO2] is -12,000 or more and 2,000 or less: V=49.589×[SiO2]+61.806×[Al2O3]+45.456×[P2O5]+41.151×[MgO]+110.26×[CaO]+50.263 ×[SrO]+55.693×[Li2O]+3.598×[Na2O]+9.503×[K2O]+6.83×[TiO2]-2.885×[ZrO2]-3746.99 G=-600.1×[SiO2]-368.987×[Al2O3]-659.214×[MgO]-361.434×[Li2O]-1184.84×[Na2O]-1524.6×[K2O]-1516.47×[ZrO2]+60922.7

[0015] A glass-ceramic having a lithium aluminosilicate composition and containing crystals and residual glass, wherein the composition of the residual glass is expressed in mole percent on an oxide basis. SiO2 25-70% Al2O3 3-35% Li2O 0.1~20% Na2O 0.1~20% K2O 0~10% A glass-ceramic in which ZrO2 is 1 to 15%, and the sum (V+D+G) of parameters V, D, and G calculated according to the following formula using the contents of the components [SiO2], [Al2O3], [P2O5], [MgO], [CaO], [SrO], [Li2O], [Na2O], [K2O], [TiO2], and [ZrO2], expressed as mole % on an oxide basis in the residual glass composition, is -9000 or more and 3000 or less. V=49.589×[SiO2]+61.806×[Al2O3]+45.456×[P2O5]+41.151×[MgO]+110.26×[CaO]+50.263 ×[SrO]+55.693×[Li2O]+3.598×[Na2O]+9.503×[K2O]+6.83×[TiO2]-2.885×[ZrO2]-3746.99 D=-72.3739×[SiO2]-24.174×[Al2O3]-78.0127×[P2O5]-80.0648×[MgO]-156.732×[CaO]-61 .4172×[Li2O]-99.7426×[Na2O]-106.162×[K2O]-199.391×[TiO2]+7.09771×[ZrO2]+7907.11 G=-600.1×[SiO2]-368.987×[Al2O3]-659.214×[MgO]-361.434×[Li2O]-1184.84×[Na2O]-1524.6×[K2O]-1516.47×[ZrO2]+60922.7 [Effects of the Invention]

[0016] The crystallized glass of the present invention has a residual glass composition within a specific range, so that crystals in the glass are easily lost when remelted, and devitrification is unlikely to occur. This reduces material loss in the production of crystallized glass, increases yield, and improves production efficiency. DETAILED DESCRIPTION OF THE INVENTION

[0017] In this specification, the use of "to" to indicate a range of values is used to mean that the values before and after it are included as the lower and upper limits, and unless otherwise specified, "to" will be used in the same sense hereinafter in this specification.

[0018] In this specification, "amorphous glass" and "crystallized glass" are collectively referred to as "glass." In this specification, "amorphous glass" refers to glass in which no diffraction peaks indicating crystals are observed by powder X-ray diffraction. "Crystallized glass" refers to "amorphous glass" that has been heat-treated to precipitate crystals, and contains crystals.

[0019] Glass-ceramics consist of a crystalline phase and "residual glass." "Residual glass" is the amorphous portion of glass-ceramics. The composition of the residual glass can be calculated by estimating the crystallization rate using the Rietveld method and then dividing the amount of crystals by the composition of the glass raw materials used. The crystallization rate can be calculated using the Rietveld method from X-ray diffraction intensity. 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] Powder X-ray diffraction measurement is carried out using CuKα radiation in the range of 2θ of 10° to 80°, and when a diffraction peak appears, the precipitated crystals are identified by, for example, the three strongest radiation method.

[0021] In this specification, "devitrification" refers to the precipitation of crystals during the melting and forming of glass. The precipitation of crystals during the melting and forming of glass reduces the transparency of the glass.

[0022] Hereinafter, "chemically strengthened glass" refers to glass after chemical strengthening treatment, and "glass for chemical strengthening" refers to glass before chemical strengthening treatment.

[0023] In this specification, unless otherwise specified, glass compositions are expressed in mole percent on an oxide basis, and mole percent is simply represented as "%."

[0024] In addition, in this specification, "substantially free" means that the content is at or below the level of impurities contained in raw materials, etc., that is, that the component is not intentionally added. When it is stated in this specification that a certain component is not substantially contained, the content of the component in question is specifically, for example, less than 0.1%.

[0025] In this specification, the term "stress profile" refers to a representation of compressive stress values with depth from the glass surface as a variable. In the stress profile, tensile stress is represented as negative compressive stress.

[0026] <Glass-ceramics> The present glass-ceramics is preferably lithium aluminosilicate glass-ceramics, that is, glass-ceramics containing SiO2, Al2O3, and Li2O as the main components. Lithium aluminosilicate glass-ceramics can be chemically strengthened by ion exchange treatment to obtain high strength.

[0027] The present crystallized glass preferably has a lithium aluminosilicate composition and has the following composition expressed in mole percent on an oxide basis: SiO2 55-80% Al2O3 3-20% Li2O 1~25% Na2O 0.1-10% K2O 0~3% ZrO20.1~5%

[0028] A preferred composition will be described below. SiO2 is a component that constitutes the glass network. It also increases chemical durability. The SiO2 content is preferably 55% or more, more preferably 57% or more, and even more preferably 60% or more. In order to increase the meltability of the glass, the SiO2 content is preferably 80% or less, more preferably 77% or less, and even more preferably 75% or less.

[0029] Al2O3 is an effective component for improving ion exchange performance during chemical strengthening and increasing surface compressive stress after strengthening. The Al2O3 content is preferably 3% or more, more preferably 4% or more, and even more preferably 5% or more. In addition, to improve meltability, the Al2O3 content is preferably 20% or less, more preferably 18% or less, and even more preferably 17% or less.

[0030] Li2O is a component that forms surface compressive stress by ion exchange and is an essential component of lithium aluminosilicate glass. The Li2O content is preferably 1% or more, more preferably 3% or more, and even more preferably 5% or more, in order to increase the compressive stress layer depth DOL after chemical strengthening. Furthermore, in order to suppress devitrification during glass production, the Li2O content is preferably 25% or less, more preferably 24% or less, and even more preferably 23% or less.

[0031] Na2O is a component that forms a surface compressive stress layer by ion exchange using a potassium-containing molten salt and also improves the meltability of glass. The Na2O content is preferably 0.1% or more, more preferably 0.5% or more, and even more preferably 1.0% or more. In order to maintain chemical durability, the Na2O content is preferably 10% or less, more preferably 8% or less, and even more preferably 6% or less.

[0032] K2O is a component that improves the meltability of glass and promotes ion exchange. K2O is an optional component, and when contained, the content is preferably 0.5% or more, more preferably 1% or more. In order to maintain chemical durability, the content of K2O is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less.

[0033] MgO, CaO, SrO, and BaO are all components that improve the meltability of glass, but tend to reduce ion exchange performance. MgO, CaO, SrO, and BaO are optional components, and when at least one of them is contained, the total content (MgO + CaO + SrO + BaO) is preferably 0.1% or more, and more preferably 0.5% or more.

[0034] When MgO is contained, the content is preferably 0.1% or more, and more preferably 0.5% or more. In order to improve the ion exchange performance, the MgO content is preferably 10% or less, and more preferably 8% or less.

[0035] When CaO is contained, the content is preferably 0.5% or more, more preferably 1% or more. In order to improve the ion exchange performance, the CaO content is preferably 5% or less, more preferably 3% or less.

[0036] When SrO is contained, the content is preferably 0.5% or more, more preferably 1% or more. In order to improve the ion exchange performance, the content of SrO is preferably 5% or less, more preferably 3% or less.

[0037] When BaO is contained, the content is preferably 0.5% or more, more preferably 1% or more. In order to improve the ion exchange performance, the content of BaO is preferably 5% or less, more preferably 1% or less, and even more preferably substantially zero.

[0038] ZnO is a component that improves the meltability of glass and may be contained. When ZnO is contained, the content is preferably 0.2% or more, more preferably 0.5% or more. To improve the weather resistance of the glass, the ZnO content is preferably 5% or less, more preferably 3% or less.

[0039] TiO2 is a component that increases the surface compressive stress due to ion exchange and may be contained. When TiO2 is contained, the content is preferably 0.1% or more. In order to suppress devitrification during melting, the content of TiO2 is preferably 5% or less, more preferably 1% or less, and even more preferably substantially zero.

[0040] ZrO2 is a component that increases the surface compressive stress due to ion exchange. The ZrO2 content is preferably 0.5% or more, more preferably 1% or more. In order to suppress devitrification during melting, the content is preferably 5% or less, more preferably 3% or less.

[0041] To color the glass, coloring components may be added within a range that does not impede the achievement of the desired chemical strengthening properties. Examples of coloring components include Co3O4, MnO2, Fe2O3, NiO, CuO, Cr2O3, V2O5, Bi2O3, SeO2, CeO2, Er2O3, and Nd2O3. These may be used alone or in combination.

[0042] The total content of coloring components is preferably 7% or less. This can prevent devitrification of the glass. The content of coloring components is more preferably 5% or less, even more preferably 3% or less, and particularly preferably 1% or less. If it is desired to increase the visible light transmittance of the glass, it is preferable that these components are substantially not contained.

[0043] Furthermore, SO3, chlorides, fluorides, etc. may be appropriately contained as fining agents during glass melting. It is preferable that As2O3 is not substantially contained. If Sb2O3 is contained, it is preferably 0.3% or less, more preferably 0.1% or less, and most preferably it is not substantially contained.

[0044] <<Residual glass>> The residual glass contained in the present glass-ceramics preferably has the following composition expressed in mole percent on an oxide basis: SiO2 25-70% Al2O3 3-35% Li2O 0.1~20% Na2O 0.1~20% K2O 0~10% ZrO21-15%

[0045] A preferred composition of the residual glass will be described below. SiO2 is an essential component of lithium aluminosilicate glass-ceramics and is also contained in the residual glass. If the SiO2 content in the residual glass is 25% or more, the weather resistance of the residual glass improves, which in turn improves the weather resistance of the glass-ceramics, making it preferable. It is more preferably 27.5% or more, and even more preferably 30% or more. Furthermore, to reduce the viscosity of the residual glass and facilitate remelting of the glass-ceramics, it is preferably 70% or less. It is more preferably 67.5% or less, and even more preferably 65% or less.

[0046] Al2O3 is 、 Al2O3 is an essential component of lithium aluminosilicate glass-ceramics and is also contained in the residual glass. If the residual glass contains 3% or more Al2O3, not only does it improve the chemical durability of the residual glass, but it also allows for chemical strengthening. It is more preferably 3.5%, and even more preferably 4.0% or more. Furthermore, to reduce the viscosity of the residual glass composition and facilitate remelting of the glass-ceramics, it is preferably 35% or less. It is more preferably 32.5% or less, and even more preferably 30% or less.

[0047] P2O5 is an optional component that not only functions as a nucleating agent for lithium aluminosilicate crystallized glass but also improves chemical strengthening ability. The P2O5 content in the residual glass is preferably 0.1% or more, more preferably 1% or more, even more preferably 2% or more, and even more preferably 3% or more. From the viewpoint of the chemical durability of the residual glass phase of the crystallized glass, the P2O5 content in the residual glass is preferably 20% or less, more preferably 18% or less, even more preferably 16% or less, and even more preferably 15% or less.

[0048] B2O3 is an optional component that reduces the viscosity of the residual glass phase and improves the crystal solubility during remelting. From the viewpoint of the chemical durability of the residual glass and the suppression of compositional changes due to the volatilization of B2O3 during remelting of the crystallized glass, its content is preferably 10% or less. It is more preferably 8% or less, even more preferably 6% or less, and even more preferably 5% or less. When B2O3 is contained in the residual glass, there is no particular lower limit for its content, but it is preferably 1% or more, and more preferably 2% or more.

[0049] Li2O is also an essential component of lithium aluminosilicate glass-ceramics and is also contained in the residual glass. If the Li2O content in the residual glass is 0.1% or more, the viscosity of the residual glass can be reduced when the glass-ceramics are remelted, making it easier to remelt the crystals. It can also improve the Young's modulus of the residual glass phase. It is more preferably 0.15% or more, and even more preferably 0.2% or more. Furthermore, from the viewpoint of the chemical durability of the residual glass phase and suppressing the reprecipitation of crystals when the glass-ceramics are remelted, it is preferably 20% or less. It is more preferably 17.5% or less, and even more preferably 15% or less.

[0050] Na2O is an essential component because it can reduce the viscosity of the residual glass in the crystallized glass when remelted. This effect can be achieved if the Na2O content in the residual glass is 0.1% or more. It is more preferably 0.2% or more, even more preferably 0.3% or more, and even more preferably 0.5% or more. Furthermore, from the perspective of the chemical durability of the residual glass, the Na2O content in the residual glass is preferably 20% or less, more preferably 17.5% or less, and even more preferably 15% or less.

[0051] K2O is an optional component that can reduce the viscosity of the residual glass in the crystallized glass when remelted. From the viewpoint of the chemical durability of the residual glass, the content of K2O is preferably 10% or less, more preferably 7.5% or less, and even more preferably 5% or less. When K2O is contained in the residual glass, there is no particular lower limit for the content, but it is preferably 0.5% or more, and more preferably 1% or more.

[0052] ZrO2 is an essential component because it not only improves the mechanical properties of the residual glass but also significantly improves its chemical durability. The ZrO2 content in the residual glass is preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more. Furthermore, in order to suppress reprecipitation of crystals when the crystallized glass is remelted, the ZrO2 content in the residual glass is preferably 15% or less, more preferably 14% or less, and even more preferably 13.5% or less.

[0053] MgO, CaO, SrO, and BaO are all optional components that enhance the meltability of glass. When MgO is contained in the residual glass, its content is preferably 0.5% or more, more preferably 1% or more. Furthermore, to suppress reprecipitation of crystals during remelting, the content of MgO in the residual glass is preferably 10% or less, more preferably 7% or less.

[0054] When the residual glass contains CaO, its content is preferably 0.5% or more, more preferably 1% or more. In order to suppress reprecipitation of crystals during remelting, the content of CaO in the residual glass is preferably 10% or less, more preferably 7% or less.

[0055] When SrO is contained in the residual glass, the content is preferably 0.5% or more, more preferably 1% or more. In order to suppress reprecipitation of crystals during remelting, the content of SrO in the residual glass is preferably 10% or less, more preferably 7% or less.

[0056] When the residual glass contains BaO, its content is preferably 0.5% or more, more preferably 1% or more. In order to suppress reprecipitation of crystals during remelting, the content of BaO in the residual glass is preferably 10% or less, more preferably 7% or less.

[0057] From the viewpoint of the strength characteristics of the glass, the TiO2 content in the residual glass is preferably 0% or more, more preferably 0.1% or more, and even more preferably 1% or more. In addition, to suppress coloration of the glass, the TiO2 content in the residual glass is preferably 7% or less, more preferably 5% or less.

[0058] From the viewpoint of improving chemical strengthening properties, it is preferable that the value calculated from the formula [Al2O3] / ([SiO2]+[Al2O3]) using the contents [SiO2] and [Al2O3] of Al2O3 and SiO2 components expressed in mole percent on an oxide basis in the residual glass of this crystallized glass is 0.07 or more. More preferably, it is 0.10 or more. Furthermore, since the viscosity of the crystallized glass increases when remelting, making it difficult to remelt the crystals, it is preferable that [Al2O3] / ([SiO2]+[Al2O3]) is 0.5 or less. More preferably, it is 0.49 or less, and even more preferably, it is 0.47 or less.

[0059] To improve the meltability of the crystals during remelting of the present crystallized glass and to improve chemical strengthening properties, the value calculated from the formula [ΣR+] / ([SiO2]+[Al2O3]) using the total content of alkali components ΣR+, SiO2, and Al2O3, expressed in mole percent on an oxide basis in the residual glass, is preferably 0.05 or more. It is more preferably 0.07 or more, and even more preferably 0.1 or more. Furthermore, from the viewpoint of the chemical durability of the residual glass phase of the crystallized glass, it is preferable that [ΣR+] / ([SiO2]+[Al2O3]) be 0.45 or less. It is more preferably 0.42 or less, even more preferably 0.40 or less, and even more preferably 0.38 or less.

[0060] In the residual glass composition of this glass-ceramics, the parameter V calculated according to the following formula using the contents of the components SiO2, Al2O3, P2O5, MgO, CaO, SrO, Li2O, Na2O, K2O, TiO2, and ZrO2, [SiO2], [Al2O3], [P2O5], [MgO], [CaO], [SrO], [Li2O], [Na2O], [K2O], [TiO2], and [ZrO2], is -600 or more and 720 or less. V=49.589×[SiO2]+61.806×[Al2O3]+45.456×[P2O5]+41.151×[MgO]+110.26×[CaO]+50.263 ×[SrO]+55.693×[Li2O]+3.598×[Na2O]+9.503×[K2O]+6.83×[TiO2]-2.885×[ZrO2]-3746.99

[0061] According to the research of the present inventors, the parameter V is a parameter that represents the ease of melting of the LAS-based crystalline phase when remelting the crystallized glass. When a defect is found in a crystallized glass article, it may be possible to reduce material loss by remelting the article. In this case, the easier the crystals are to melt when remelting the crystallized glass, the easier the remelting will be, and the higher the production efficiency can be.

[0062] The parameter V is preferably −600 or more because it is easy to obtain a transparent LAS-based crystallized glass, more preferably −500 or less, even more preferably −400 or less, and even more preferably −300 or less.

[0063] The parameter V is preferably 720 or less because the crystal is easily remelted, more preferably 700 or less, and even more preferably 680 or less.

[0064] The parameter G calculated based on the following formula using the contents of each of the components SiO2, Al2O3, MgO, Li2O, K2O and ZrO2, expressed in mole percent on an oxide basis, in the residual glass composition of the present crystallized glass is preferably -13,000 or more and less than 1,000. G=-600.1×[SiO2]-368.987×[Al2O3]-659.214×[MgO]-361.434×[Li2O]-1184.84×[Na2O]-1524.6×[K2O]-1516.47×[ZrO2]+60922.7

[0065] According to the research of the present inventors, the parameter G represents the ease of re-precipitation of LAS-based crystals when the crystallized glass is remelted.

[0066] When the parameter G is −13,000 or more, it is possible to design a residual glass phase that exhibits high strength while suppressing the precipitation of LAS-based crystals, more preferably −12,000 or more, and even more preferably −11,000 or more.

[0067] If the parameter G is less than 1000, devitrification due to reprecipitation of LAS-based crystals can be suppressed, which is preferable from the viewpoint of manufacturing properties.

[0068] It is preferable that the parameter D calculated according to the following formula using the contents of the components [SiO2], [Al2O3], [MgO], [P2O5], [CaO], [Li2O], [Na2O], [K2O], [TiO2] and [ZrO2], expressed in mole % on an oxide basis, SiO2, Al2O3, MgO, P2O5, CaO, Li2O, Na2O, K2O, TiO2 and ZrO2 in the residual glass composition, is 1400 or more and 2500 or less. D=-72.3739×[SiO2]-24.174×[Al2O3]-78.0127×[P2O5]-80.0648×[MgO]-156.732×[CaO]-61 .4172×[Li2O]-99.7426×[Na2O]-106.162×[K2O]-199.391×[TiO2]+7.09771×[ZrO2]+7907.11

[0069] According to the research of the present inventors, the parameter D represents the ease with which Zr-based crystals are generated when the glass-ceramics is remelted.

[0070] Parameter D of 1400 or more is preferable in that devitrification due to precipitation of Zr-based crystals can be suppressed while a high-strength residual glass can be designed, more preferably 1450 or more, and even more preferably 1500 or more.

[0071] The parameter D is preferably 2500 or less, since Zr-based defects occurring during remelting of the crystallized glass can be suppressed, more preferably 2400 or less, and even more preferably 2300 or less.

[0072] The sum of the parameter V and the parameter G (V+G) is preferably 2000 or less.

[0073] If the sum (V+G) of the parameters V and G is 2000 or less, the reprecipitation of LAS-based crystals that occurs when the glass-ceramics is returned to the process can be suppressed, and transparent glass-ceramics can be obtained again. The sum (V+G) of the parameters V and G is preferably 1500 or less, and more preferably 1000 or less.

[0074] Furthermore, if the sum (V+G) of the parameter V and the parameter G is preferably −12000 or more, a high-strength residual glass composition can be designed. The sum (V+G) of the parameter V and the parameter G is more preferably −11000 or more, and even more preferably −10500 or more.

[0075] The sum of the parameters V, D, and G (V+D+G) is preferably 3,000 or less.

[0076] The sum (V+D+G) of parameters V, D, and G is preferably 3000 or less from the viewpoint of suppressing the generation of LAS-based crystals and Zr-based crystals when the glass-ceramics are remelted. (V+D+G) is more preferably 2750 or less, and even more preferably 2500 or less. In addition, (V+D+G) is preferably -9000 or more in terms of designing the residual glass composition of high-strength LAS-based transparent glass-ceramics, more preferably -8500 or more, and even more preferably -8000 or more.

[0077] <Crystal> In order to improve mechanical properties, the crystallized glass preferably has a crystallization rate of 50 to 90%, more preferably 53 to 87%, even more preferably 55 to 85%, and even more preferably 60 to 80%.

[0078] The crystals contained in the present crystallized glass are preferably crystals containing SiO2, Al2O3, and Li2O (LAS-based crystals), because the inclusion of LAS-based crystals allows for extremely high strength to be obtained by chemical strengthening treatment.

[0079] The present glass-ceramics more preferably contains at least one LAS-based crystal selected from β-spodumene crystals, petalite crystals, and eucryptite crystals.

[0080] The proportion of LAS-based crystals in the crystals contained in this crystallized glass is preferably 30 to 70 mass%. When the LAS-based crystals are 30 mass% or more, the strength can be sufficiently improved by chemical strengthening treatment. When the LAS-based crystals are 70 mass% or less, the transparency can be improved. This is thought to be because the particle size of the crystals becomes smaller due to the generation of crystals with different compositions. The proportion of LAS-based crystals contained in the crystallized glass can be calculated by identifying the precipitated crystals by powder X-ray diffraction and estimating the amount of crystallization using the Rietveld method from the obtained diffraction intensity.

[0081] For example, the crystallized glasses shown in Examples 1, 2, and 9 in the Examples below contain precipitated β-spodumene. The stoichiometric composition of β-spodumene is expressed as LiAlSi2O6, and it is generally a crystal that exhibits diffraction peaks at Bragg angles (2θ) of 25.55°±0.05°, 22.71°±0.05°, and 28.20°±0.05° in the X-ray diffraction pattern. However, the obtained X-ray diffraction pattern is slightly shifted to the higher angle side, and the precipitation of β-spodumene crystals containing defects can be confirmed by using the Rietveld method. Specifically, Li 0.4 □ 0.6 AlSi2O6, where □ denotes the amount of defects.

[0082] Examples of crystals other than LAS-based crystals include lithium metasilicate, lithium disilicate, and lithium phosphate. By including crystals other than LAS-based crystals, the transparency of the glass-ceramics can be improved.

[0083] <Method of manufacturing crystallized glass and chemically strengthened glass> Chemically strengthened glass can be produced by chemically strengthening this glass-ceramics. Glass-ceramics is produced by a method in which amorphous glass is heat-treated to crystallize it.

[0084] (Amorphous Glass Manufacturing) Amorphous glass can be produced, for example, by the following method. The production method described below is an example of producing a plate-shaped chemically strengthened glass.

[0085] Glass raw materials are blended to obtain glass of a desired composition, and then 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, and slowly cooled. Alternatively, the molten glass may be formed into a block, slowly cooled, and then cut into a plate.

[0086] (crystallization treatment) The amorphous glass obtained by the above procedure is subjected to a heat treatment to obtain crystallized glass.

[0087] The heat treatment may be 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 for a certain period of time at a second treatment temperature higher than the first treatment temperature, or a one-stage heat treatment in which the temperature is maintained at a specific treatment temperature and then cooled to room temperature.

[0088] In the case of two-stage heat treatment, the first treatment temperature is preferably in a temperature range where the crystal nucleation rate is high in the glass composition, and the second treatment temperature is preferably in a temperature range where the crystal growth rate is high in the glass composition. Also, it is preferable to maintain the first treatment temperature for a long time so that a sufficient number of crystal nuclei are generated. By generating a large number of crystal nuclei, the size of each crystal becomes small, and highly transparent crystallized glass is obtained.

[0089] In the case of a two-stage treatment, for example, the first treatment temperature is held at 500°C to 700°C for 1 to 6 hours, and then the second treatment temperature is held at 600°C to 800°C for 1 to 6 hours. In the case of a one-stage treatment, for example, the temperature is held at 500°C to 800°C for 1 to 6 hours.

[0090] The crystallized glass obtained by the above procedure is ground and polished as necessary to form a crystallized glass plate. When the crystallized glass plate 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, because a compressive stress layer is formed on the end surface by the subsequent chemical strengthening treatment.

[0091] (chemical strengthening treatment) Chemical strengthening is a process in which glass is brought into contact with a metal salt (e.g., potassium nitrate) by immersion in a melt of a metal salt containing metal ions with a large ionic radius (typically Na ions or K ions), thereby replacing metal ions with a small ionic radius (typically Na ions or Li ions) in the glass with metal ions with a large ionic radius (typically Na ions or K ions for Li ions, and K ions for Na ions).

[0092] 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. Also, to create a large compressive stress through ion exchange, it is preferable to use "Na-K exchange," which exchanges Na ions in the glass with K ions.

[0093] Examples of molten salts used in chemical strengthening include nitrates, sulfates, carbonates, and chlorides. Nitrates include lithium nitrate, sodium nitrate, potassium nitrate, cesium nitrate, and silver nitrate. Sulfates include lithium sulfate, sodium sulfate, potassium sulfate, cesium sulfate, and silver sulfate. Carbonates include lithium carbonate, sodium carbonate, and potassium carbonate. Chlorides include lithium chloride, sodium chloride, potassium chloride, cesium chloride, and silver chloride. These molten salts may be used alone or in combination.

[0094] The conditions for the chemical strengthening treatment, such as time and temperature, can be selected taking into consideration the glass composition and the type of molten salt. For example, the present glass-ceramics may be chemically strengthened at 450°C or less for 1 hour or less. Specifically, for example, the glass may be immersed in a molten salt containing 0.3% by mass of Li and 99.7% by mass of Na (e.g., a mixed salt of lithium nitrate and sodium nitrate) at 450°C for about 0.5 hours.

[0095] The chemical strengthening treatment may be performed by, for example, two-stage ion exchange as follows: First, the crystallized glass is immersed in a metal salt (e.g., sodium nitrate) containing Na ions at a temperature of preferably about 350 to 500°C for preferably about 0.1 to 10 hours. This causes ion exchange between the Li ions in the crystallized glass and the Na ions in the metal salt, forming a relatively deep compressive stress layer.

[0096] Next, the substrate is immersed in a metal salt containing K ions (e.g., potassium nitrate) at a temperature of preferably about 350 to 500°C for about 0.1 to 10 hours. This generates a large compressive stress in the compressive stress layer formed in the previous treatment, for example, within a depth of about 10 μm. This two-stage treatment makes it easy to obtain a stress profile with a large surface compressive stress value.

[0097] Chemically strengthened glass obtained by chemically strengthening this glass-ceramics is also useful as cover glass for electronic devices such as mobile devices such as mobile phones and smartphones. It is 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. It is also useful as building materials such as window glass, tabletops, interiors of automobiles and airplanes, and their cover glass, as well as for curved housings. [Example]

[0098] The present invention will be described below with reference to examples, but the present invention is not limited thereto.

[0099] <Preparation of amorphous glass> Glass raw materials were mixed to obtain the glass composition shown in Table 1 in mole percent based on oxides, and weighed out to obtain 800 g of glass. The mixed glass raw materials were then placed in a platinum crucible and placed in an electric furnace at 1600°C, where they were melted for about 5 hours, degassed, and homogenized.

[0100] The resulting molten glass was poured into a mold and held at the glass transition temperature for 1 hour, and then cooled to room temperature at a rate of 0.5°C / min to obtain a glass block.

[0101] Glass-ceramics can be obtained by heat-treating the glass having the composition shown in Table 1. In Table 1, blank cells indicate that the element is not contained.

[0102] [Table 1]

[0103] <Crystallization treatment and evaluation of crystallized glass> For G1 to G4, the obtained glass blocks were processed to 50 mm x 50 mm x 1.5 mm and then heat-treated under the conditions listed in Tables 2 and 3 to obtain crystallized glass. In the crystallization conditions column of the table, the upper row indicates the nucleation treatment conditions and the lower row indicates the crystal growth treatment conditions. For example, if the upper row indicates 650°C for 2 hours and the lower row indicates 850°C for 2 hours, this means that the temperature was held at 650°C for 2 hours, followed by another 2 hours at 850°C. G1 to G8 are examples, and G9 is a comparative example.

[0104] The resulting crystallized glass was processed and mirror-polished to obtain a crystallized glass plate with a thickness t of 0.7 mm. A portion of the crystallized glass was crushed and subjected to powder X-ray diffraction analysis under the following conditions to identify the precipitated crystals. The crystallization rate was calculated from the obtained diffraction intensity using the Rietveld method. The results are shown in Tables 2 and 3. The residual glass composition, expressed in mole percent based on oxides, is shown in the SiO2-TiO2 columns of Tables 2 and 3. Measurement equipment: Rigaku SmartLab X-ray used: CuKα ray Measurement range: 2θ=10°~80° Speed: 10° / min Step: 0.02°

[0105] [Table 2]

[0106] [Table 3]

[0107] As shown in Tables 2 and 3, in Examples 1 to 8, which are working examples, the values of [Al2O3] / ([SiO2]+[Al2O3]), [ΣR+] / ([SiO2]+[Al2O3]), and the parameters V, G, D, (V+D), and (V+D+G) are all within the ranges specified in the present invention, and devitrification is likely to disappear and reprecipitation of devitrification upon remelting. On the other hand, in Example 9, which is a comparative example, these values are outside the ranges specified in the present invention, and devitrification is likely to disappear and reprecipitation of devitrification upon remelting. Therefore, it can be said that glasses in which the values of [Al2O3] / ([SiO2]+[Al2O3]), [ΣR+] / ([SiO2]+[Al2O3]), and the parameters V, G, D, (V+D), and (V+D+G) are within the ranges specified in the present invention have excellent recyclability.

[0108] Although the present invention has been described in detail 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 a Japanese patent application (Patent Application No. 2020-140348) filed on August 21, 2020, the entire contents of which are incorporated by reference. All references cited herein are incorporated in their entirety.

Claims

1. A glass-ceramic having a lithium aluminosilicate composition and containing crystals and residual glass, The composition of the crystallized glass is expressed in mole percent based on oxides, SiO 2 60-75% Al 2 O 3 3-17% Li 2 O 18.1-25% Na 2 O 0.1-1.58% K2O 3% or less ZrO 2 1.24-5% TiO 2 is 1% or less, Does not contain MgO, Contains virtually no coloring ingredients Contains at least one LAS-based crystal selected from β-spodumene crystal, petalite crystal, and eucryptite crystal, The composition of the residual glass is expressed as mole percent based on oxides. Yes ２ 25~70% <h2 style=";text-align:left;direction:ltr">Al<h2 style=";text-align:left;direction:ltr"> ２ <h2 style=";text-align:left;direction:ltr"> O<h2 style=";text-align:left;direction:ltr"> ３ <h2 style=";text-align:left;direction:ltr"> 3~355% Li ２ O 0.1~20% Na ２ O0.1~20% K ２ O 0~10% ZrO ２ 1 to 15%, and expressed in mole percent based on the oxides in the residual glass, SiO ２ , Al ２ O ３ , P ２ O ５ , MgO, CaO, SrO, Li ２ O, Na ２ O.K. ２ O, TiO ２ and ZrO ２ The content of each component [SiO ２ ], [Al ２ O ３ ], [P ２ O ５ ], [MgO], [CaO], [SrO], [Li ２ O], [Na ２ O], [K ２ O], [TiO ２ ] and [ZrO ２ ] is calculated based on the following formula, the parameter V is -600 or more and 720 or less, V=49.589×[SiO ２ ]+61.806×[A5 ２ O ３ ]+45.456×[P ２ O ５ ]+\41.151×[MgO]+110.26×[CO]+50.263×[SrO]+55.693×[- ２ O]+3.598×[N ２ O]+9.503×[K ２ O]+6.83×[T-O ２ ]-2.885×[ZrO ２ ]-3746.99 The [SiO ２ ], [Al ２ O ３ ] to obtain the compound of formula [Al ２ O ３ ] / ([SiO ２ ]+[Al ２ O ３ ]) is 0.07 or more and 0.5 or less, the total content of alkali components in the residual glass expressed in mole percent on an oxide basis [ΣR+], SiO ２ and Al ２ O ３ Using the content of each component, the formula [ΣR+] / ([SiO ２ ]+[Al ２ O ３ ]) is equal to or greater than 0.05 and equal to or less than 0.42, The [SiO ２ ], [Al ２ O ３ ], [MgO], [Li ２ O], [Na ２ O], [K ２ O] and [ZrO ２ ] is calculated based on the following formula using the above formula, and the parameter G is equal to or greater than −13,000 and less than 1,000, G=-600.1×[SiO ２ ]-368.987×[AS ２ O ３ ]-659.214×[MO]-361.334×[L ２ O]-1184.84×[N ２ O]-1524.6×[K ２ O]-1516.47×[ZrO ２ ]+60922.7 The [SiO ２ ], [Al ２ O ３ ], [MgO], [P ２ O ５ ], [CaO], [Li ２ O], [Na ２ O], [K ２ O], [TiO ２ ] and [ZrO ２ ] and the parameter D calculated based on the following formula is 1400 or more and 2500 or less, D=-72.3739×[SiO ２ ]-24.174×[A5 ２ O ３ ]-78.0127×[P ２ O ５ ]-80.0648×[MO]-156.732×[CO]-61.4172×[L ２ O]-99.7426×[N ２ O]-106.162×[K ２ O]-199.391×[T-O ２ ]+7.09771×[ZrO ２ ]+7907.11 The sum (V+G) of the parameter V and the parameter G is −12000 or more and 2000 or less, and the sum of the parameter V, the parameter D, and the parameter G (V+D+G) is −9000 or more and 3000 or less; Crystallized glass.

2. 2. The crystallized glass according to claim 1, wherein the crystallization rate is 50 to 90%.

3. 2. The crystallized glass according to claim 1, wherein the crystals contained in the crystallized glass are LAS-based crystals in a proportion of 30 to 70 mass %.

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