Glass-ceramics with quartz solid solution

Abstract

The invention relates to quartz mixed crystal glass-ceramics, and to precursors thereof, which are characterized by excellent mechanical and optical properties, and which can be used in particular as dental restorative materials.

Description

[0001] This invention relates to glass-ceramics having a quartz solid solution phase, which are particularly suitable for use in dentistry, preferably for the preparation of dental restorations, and to precursors for the preparation of these glass-ceramics.

[0002] Glass ceramics with a quartz solid solution phase are basically known from existing technology.

[0003] DE2507131A1 describes a special magnesium aluminate glass-ceramic containing 45 to 65 wt% SiO2, 20 to 35 wt% Al2O3, and 9 to 15 wt% MgO. The host material, made of glass-ceramic, has a heterogeneous structure because the crystal structure of the surface layer differs from that of the interior. This results in surface compressive stress that significantly affects the mechanical properties, thus machining the surface layer leads to a deterioration of these properties. A high-quartz solid solution is detected in the surface layer of the host, while a low-quartz solid solution is detected in the interior.

[0004] JP2000 / 063144A discloses a magnesium aluminum silicate glass substrate for preparing a storage medium containing 30 to 60 mol% SiO2 and a large amount of B2O3.

[0005] GB2172282A describes magnesium aluminum silicate glass ceramics containing 30 to 55 wt% SiO2 and 10 to 40 wt% Al2O3. These glass ceramics are intended for microelectronic applications, particularly as coatings for substrates such as aluminum, and in addition to high strength, they possess a suitable dielectric constant in the range of 7 to 10 and high resistivity.

[0006] WO2012 / 143137A1 describes a glass-ceramic body containing at least 10.1% by weight of Al2O3 and having different crystalline phases in different regions.

[0007] WO2015 / 155038A1 describes glass-ceramics with a quartz solid solution phase for dental use. No glass-ceramics containing several quartz solid solution phases are described.

[0008] In their article in J. Biomed. Mater. Res. Part B: 100B: 463-470 (2012), M. Dittmer and C. Rüssel described glass ceramics with a high-quartz or low-quartz solid solution phase as the main crystalline phase, containing up to 55.1 wt% SiO2 and at least 25.9 wt% Al2O3.

[0009] In conclusion, the strength and translucency achieved with these known glass ceramics are not entirely satisfactory for their application as dental materials.

[0010] Therefore, the present invention addresses the problem of providing a glass-ceramic with a combination of high strength and good translucency. The glass-ceramic should also have a coefficient of thermal expansion that can be adjusted over a wide range. Furthermore, the glass-ceramic should be easily processed into dental restorations and thus be excellently suited as a restorative dental material.

[0011] This problem is solved by a glass-ceramic having two different quartz solid solution phases according to the invention. The subject matter of the invention also includes the starting glass according to the invention, the method according to the invention, and the application according to the invention.

[0012] The glass-ceramic according to the present invention is characterized in that it comprises the following components

[0013] Component weight %

[0014] SiO2 68.0 to 81.0

[0015] Li2O 6.0 to 14.0

[0016] Al2O3 1.0 to 8.0

[0017] It contains at least two different quartz solid solution phases.

[0018] This glass-ceramic, also referred to below as "glass-ceramic with multiple quartz solid solution phases," surprisingly exhibits a favorable combination of mechanical and optical properties desired for restorative dental materials. The glass-ceramic possesses high strength, and it can be readily shaped into dental restorations through pressing or machining. Furthermore, unexpectedly, very good optical properties can still be achieved by providing multiple quartz solid solution phases. This is because many subcrystalline phases negatively impact the optical properties of glass-ceramics. For example, they reduce translucency, and they also impair the possibility of imparting color to the glass-ceramic, leading to considerable difficulty in mimicking the color of the natural tooth material to be replaced.

[0019] Furthermore, it has been shown that the coefficient of thermal expansion of the glass-ceramics according to the invention can be varied over a wide range by the type and amount of the formed quartz solid solution phase. Finally, it has also been found that the glass-ceramics according to the invention can be densely sintered at higher temperatures than lithium silicate-quartz glass-ceramics without losing their shape.

[0020] The term "quartz solid solution phase" refers to a SiO2 crystalline phase in which foreign atoms are bonded to interstitial or lattice sites within the SiO2 crystal lattice. These foreign atoms can be, in particular, Al, as well as Li, Mg, and / or Zn. Al is preferably present at a molar concentration corresponding to the sum of the molar concentrations of Li, twice the molar concentrations of Mg, and twice the molar concentrations of Zn.

[0021] The quartz solid solution phase can be stoichiometric or non-stoichiometric. A stoichiometric quartz solid solution phase refers to those crystalline phases in which the ratio of the number of silicon atoms to the number of one of the foreign atoms is x:y, where x and y are integers in the range of 1 to 8, particularly integers in the range of 1 to 5. In a preferred embodiment, the glass-ceramic comprises at least one, preferably at least two, non-stoichiometric quartz solid solutions.

[0022] At least one quartz solid solution phase may be a stoichiometric or non-stoichiometric aluminosilicate crystalline phase. In a preferred embodiment, the glass-ceramic comprises at least one, preferably at least two, stoichiometric or non-stoichiometric aluminosilicate crystalline phases. In a particularly preferred embodiment, the glass-ceramic comprises at least one, preferably at least two, non-stoichiometric aluminosilicate crystalline phases. In this context, a stoichiometric aluminosilicate crystalline phase is understood to be one in which the ratio of the number of silicon atoms to the number of aluminum atoms is x:y, where x and y are integers in the range of 1 to 8, particularly those in the range of 1 to 5. Examples of stoichiometric aluminosilicate crystalline phases are nepheline (LiAlSiO4), spodumene (LiAlSi2O6), and lepidolite (LiAlSi4O3). 10 ) and cordierite (Mg2Al4Si5O 18 ).

[0023] The glass-ceramic according to the invention preferably comprises at least two different quartz solid solution phases, which are used in Cu Kα The highest intensity reflection peaks in the X-ray powder diffraction of the radiation are each in the 2θ range of 25 to 26.7°, preferably in the 2θ range of 25.5° to 26.6°, and particularly preferably in the 2θ range of 25.8° to 26.5°.

[0024] Furthermore, it is preferable to use glass-ceramics containing two different quartz solid solution phases, which are suitable for use with Cu Kα The highest intensity reflection peak in the X-ray powder diffraction of the radiation has a spacing of at least 0.2° 2θ, preferably at least 0.3° 2θ, particularly preferably at least 0.4° 2θ, especially 0.2 to 0.7° 2θ, preferably 0.3 to 0.6° 2θ, particularly preferably 0.4 to 0.5° 2θ.

[0025] The quartz solid solution phase of the glass-ceramic according to the present invention can be particularly utilized by using Cu. Kα X-ray powder diffraction was used for detection. The quartz solid solution phase showed characteristic peak shapes, where each characteristic peak originated from the low-quartz peak shape but shifted to different 2θ values. This was observed in... Figure 1The X-ray powder diffraction pattern of the glass-ceramic obtained in Example 19 is used for illustration. Several peak types contained in the PDF-4+ 2020 (International Centre for Diffraction Data) database are reproduced below the X-ray powder diffraction pattern. The peak type of low-quartz (α-SiO2) is marked with the letter "A" and shows the peak with the highest intensity between 2θ and 26.6°. In the X-ray powder diffraction pattern, two quartz solid solution phases can be seen, whose peak types are shifted to smaller 2θ values ​​compared to the low-quartz peak type, with their highest intensity peaks located at 2θ at 26.5° and 2θ at 26.0°, respectively.

[0026] The glass-ceramic with a multi-quartz solid solution phase according to the invention contains, in particular, 70.0 to 79.0% by weight, especially preferably 73.0 to 76.0% by weight of SiO2.

[0027] Further preferably, the glass-ceramic according to the invention contains 7.5 to 13.0% by weight, particularly preferably 9.0 to 12.0% by weight of Li₂O. It is believed that Li₂O reduces the viscosity of the glass matrix and thus promotes the crystallization of the desired phase.

[0028] In a preferred embodiment, the glass-ceramic according to the invention comprises 2.0 to 6.5% by weight, particularly preferably 3.0 to 6.0% by weight of Al2O3.

[0029] In another preferred embodiment, the glass-ceramic contains 1.0 to 7.0% by weight, preferably 2.5 to 5.0% by weight, and particularly preferably 3.0 to 4.4% by weight of P2O5. P2O5 is considered to act as a nucleating agent.

[0030] Preferably, the glass ceramic contains 1.0 to 8.0% by weight, more preferably 1.0 to 5.5% by weight, and particularly preferably 1.5 to 2.5% by weight of oxides of monovalent elements selected from K₂O, Na₂O, Rb₂O, Cs₂O, and mixtures thereof. I 2O.

[0031] Particularly preferably, the glass contains a specified amount of oxide Me of at least one, particularly all, of the following monovalent elements. I 2O:

[0032] Component weight %

[0033] K2O 0 to 5.0

[0034] Na₂O 0 to 2.0

[0035] Rb2O 0 to 8.0

[0036] Cs2O 0 to 7.0.

[0037] In a particularly preferred embodiment, the glass-ceramic according to the invention contains 0 to 5.0% by weight, preferably 1.0 to 3.5% by weight, and particularly preferably 1.5 to 2.5% by weight of K2O.

[0038] Furthermore, preferably, the glass-ceramic contains 0 to 9.0% by weight, more preferably 2.0 to 8.0% by weight, and particularly preferably 3.0 to 7.0% by weight of an oxide of a divalent element selected from CaO, MgO, SrO, ZnO, and mixtures thereof. II O.

[0039] In another preferred embodiment, the glass ceramic contains less than 2.0% by weight of BaO. In particular, the glass ceramic is substantially free of BaO.

[0040] Preferably, the glass-ceramic contains a specified amount of oxide of at least one, particularly all, of the following divalent elements, Me. II O:

[0041] Component weight %

[0042] CaO 0 to 3.0

[0043] MgO 0 to 6.0

[0044] SrO 0 to 5.0

[0045] ZnO 0 to 3.0

[0046] In a particularly preferred embodiment, the glass-ceramic according to the invention comprises 0 to 6.0% by weight, particularly 0.1 to 6.0% by weight, preferably 1.0 to 5.5% by weight, more preferably 2.0 to 5.0% by weight, especially preferably 2.5 to 4.5% by weight, and most preferably 3.0 to 4.0% by weight of MgO.

[0047] Furthermore, it is preferred to contain 0 to 5.0% by weight, more preferably 1.0 to 4.0% by weight, and particularly preferably 2.0 to 3.0% by weight of oxides of trivalent elements selected from B2O3, Y2O3, La2O3, Ga2O3, In2O3, and mixtures thereof. III Glass ceramics of 2O3.

[0048] Particularly preferably, the glass-ceramic contains a specified amount of oxide of at least one, particularly all, of the following trivalent elements, Me. III 2O3:

[0049] Component weight %

[0050] B2O3 0 to 4.0

[0051] Y2O3 0 to 5.0

[0052] La2O30 to 5.0

[0053] Ga2O30 to 3.0

[0054] In₂O₃ 0 to 5.0

[0055] Furthermore, it is preferred to contain 0 to 10.0% by weight, and particularly preferred 0 to 8.0% by weight of an oxide of a tetravalent element selected from ZrO2, TiO2, SnO2, CeO2, GeO2, and mixtures thereof. IV O2 glass ceramics.

[0056] Particularly preferably, the glass-ceramic contains a specified amount of an oxide of at least one, particularly all, of the following tetravalent elements, Me. IV O2:

[0057] Component weight %

[0058] ZrO20 to 3.0

[0059] TiO20 to 4.0

[0060] SnO2 0 to 3.0

[0061] GeO2 0 to 9.0, especially 0 to 8.0

[0062] CeO2 0 to 4.0.

[0063] In another embodiment, the glass-ceramic comprises 0 to 8.0% by weight, preferably 0 to 6.0% by weight, of an oxide of a pentavalent element selected from V₂O₅, Ta₂O₅, Nb₂O₅, and mixtures thereof. V 2O5.

[0064] Particularly preferably, the glass-ceramic contains a specified amount of oxide of at least one, particularly all, of the following pentavalent elements, Me. V 2O5:

[0065] Component weight %

[0066] V2O5 0 to 2.0

[0067] Ta2O5 0 to 5.0

[0068] Nb₂O₅ 0 to 5.0

[0069] In another embodiment, the glass-ceramic comprises 0 to 5.0% by weight, preferably 0 to 4.0% by weight, of an oxide of a hexavalent element selected from WO3, MoO3, and mixtures thereof. VI O3.

[0070] Particularly preferably, the glass-ceramic contains a specified amount of at least one, and in particular all, of the following oxides Me. VI O3:

[0071] Component weight %

[0072] WO3 0 to 3.0

[0073] MoO3 0 to 3.0

[0074] In another embodiment, the glass ceramic according to the invention contains 0 to 1.0% by weight, particularly 0 to 0.5% by weight, of fluorine.

[0075] Particularly preferred are glass-ceramics containing at least one, preferably all, of the following components:

[0076] Component weight %

[0077] SiO2 68.0 to 81.0

[0078] Li2O 6.0 to 14.0

[0079] Al2O3 1.0 to 8.0

[0080] P2O5 1.0 to 7.0

[0081] Me I 2O 1.0 to 8.0

[0082] Me II O 0 to 9.0

[0083] Me III 2O3 1.0 to 8.0

[0084] Me IV O2 0 to 10.0

[0085] Me V 2050 to 8.0

[0086] Me VI O30 to 5.0

[0087] Fluorine 0 to 1.0,

[0088] Among them Me I 2O, Me II O, Me III 2O3, Me IV O2, Me V 2O5 and Me VI O3 is defined as above.

[0089] In another particularly preferred embodiment, the glass-ceramic comprises at least one, preferably all, of the following components:

[0090] Component weight %

[0091] SiO2 68.0 to 81.0

[0092] Li2O 8.0 to 14.0

[0093] Al2O3 1.0 to 8.0

[0094] P2O5 1.0 to 7.0

[0095] K2O 0 to 5.0

[0096] Na₂O 0 to 2.0

[0097] Rb2O 0 to 8.0

[0098] Cs2O 0 to 7.0

[0099] CaO 0 to 3.0

[0100] MgO 0 to 6.0

[0101] SrO 0 to 5.0

[0102] ZnO 0 to 3.0

[0103] B2O3 0 to 4.0

[0104] Y2O3 0 to 5.0

[0105] La2O3 0 to 5.0

[0106] Ga2O3 0 to 3.0

[0107] In₂O₃ 0 to 5.0

[0108] ZrO2 0 to 3.0

[0109] TiO2 0 to 4.0

[0110] SnO2 0 to 3.0

[0111] GeO2 0 to 9.0, especially 0 to 8.0

[0112] CeO2 0 to 4.0

[0113] V2O5 0 to 2.0

[0114] Ta2O5 0 to 5.0

[0115] Nb₂O₅ 0 to 5.0

[0116] WO3 0 to 3.0

[0117] MoO3 0 to 3.0

[0118] Fluorine content: 0 to 1.0.

[0119] Some of the above components can be used as colorants and / or fluorescent agents. The glass-ceramics according to the invention may also contain additional colorants and / or fluorescent agents. These can be selected, for example, from Bi₂O₃ or Bi₂O₅, and particularly from other inorganic pigments and / or oxides of d and f elements, such as oxides of Mn, Fe, Co, Pr, Nd, Tb, Er, Dy, Eu, and Yb. With the aid of these colorants and fluorescent agents, glass-ceramics can be readily colored to mimic desired optical properties, especially those of natural dental materials. Surprisingly, this is readily possible despite the existence of several quartz solid solution phases.

[0120] In a preferred embodiment of the glass-ceramic, the molar ratio of SiO2 to Li2O is in the range of 2.2 to 6.0, preferably 2.8 to 5.0, and particularly preferably 3.0 to 4.0. Surprisingly, the preparation of the glass-ceramic with a multi-quartz solid solution phase of the present invention is possible within these broad ranges.

[0121] Further preferably, the glass-ceramic according to the invention contains lithium pyrosilicate or lithium metasilicate as an additional crystalline phase, particularly as the main crystalline phase. Particularly preferably, the glass-ceramic according to the invention contains lithium pyrosilicate as an additional crystalline phase, particularly as the main crystalline phase.

[0122] The term "dominant crystalline phase" refers to the crystalline phase with the highest weight fraction among all crystalline phases present in a glass-ceramic. The amount of the crystalline phase is determined specifically by the Rietveld method. For example, a suitable procedure for the quantitative analysis of crystalline phases using the Rietveld method is described in M. Dittmer's dissertation "Gläser und Glaskeramiken im System MgO-Al2O3-SiO2 mit ZrO2 als Keimbildner", University of Jena 2011.

[0123] Preferably, the glass-ceramic according to the invention contains at least 20% by weight, preferably 25 to 55% by weight, and particularly preferably 30 to 55% by weight of lithium pyrosilicate crystals.

[0124] More preferably, the glass-ceramic according to the invention contains 0.2 to 28% by weight, preferably 0.2 to 25% by weight, of a quartz solid solution.

[0125] The glass-ceramics with a multi-quartz solid solution phase according to the present invention are characterized by particularly good mechanical and optical properties, and can be formed by heat treatment of the corresponding starting glass or the corresponding starting glass with a core. Therefore, these materials can be used as precursors for the glass-ceramics with a multi-quartz solid solution phase according to the present invention.

[0126] The type and, in particular, amount of the crystalline phase formed can be controlled by the composition of the starting glass and the applied heat treatment for preparing glass-ceramics from the starting glass. Examples illustrate this by varying the composition of the starting glass and the applied heat treatment.

[0127] The glass-ceramic exhibits a high biaxial fracture strength, preferably at least 200 MPa, and particularly preferably 250 to 460 MPa. The biaxial fracture strength is determined according to ISO 6872 (2008) (three-ball piston test).

[0128] The glass-ceramic according to the invention has a density, particularly 3.0 to 14.0 × 10⁻⁶. -6 K -1 Preferably 5.0 to 14.0·10 -6 K -1 The preferred values ​​are 7.0 to 14.0·10. -6 K -1 The coefficient of thermal expansion (CTE) is measured in the range of 100 to 500 °C. CTE is determined according to ISO 6872 (2008). Adjusting the coefficient of thermal expansion to a desired value is achieved, in particular, by the type and amount of crystalline phases present in the glass-ceramic and by the chemical composition of the glass-ceramic.

[0129] According to British Standard BS 5612, the translucency of glass ceramics is determined by the contrast ratio (CR value), which is preferably between 40 and 92.

[0130] The specific combination of properties present in the glass-ceramic according to the invention even allows it to be used as a dental material, particularly as a material for preparing dental restorations.

[0131] The present invention also relates to precursors of corresponding compositions from which the glass-ceramics of the present invention, having a multi-quartz solid solution phase, can be prepared by heat treatment. These precursors are starting glasses of corresponding compositions and starting glasses of corresponding compositions with nucleations. The term "corresponding composition" means that these precursors contain the same amount of the same components as the glass-ceramics; for both glasses and glass-ceramics, components are typically calculated in terms of oxides, except for fluorine.

[0132] Therefore, the present invention also relates to starting glasses containing components of glass-ceramics having a multi-quartz solid solution phase according to the present invention.

[0133] Therefore, the starting glass according to the invention specifically contains suitable amounts of SiO2, Li2O, and Al2O3 required for forming the glass-ceramic with a multi-quartz solid solution phase according to the invention. Furthermore, the starting glass may also contain other components as specified above for the glass-ceramic with a multi-quartz solid solution phase according to the invention. All such embodiments are preferred for the composition of the starting glass, and are also specified as preferred for the composition of the glass-ceramic with a multi-quartz solid solution phase according to the invention.

[0134] Particularly preferred is the starting glass in the form of powder, granules, or a powder compact pressed from powder or granules. Compared to bulk glass, such as that obtained by pouring molten glass into a mold, the starting glass in the above form has a large inner surface area where subsequent crystallization of several quartz solid solution phases can occur.

[0135] The present invention also relates to a starting glass containing nuclei for the crystallization of various quartz solid solution phases. Preferably, the starting glass further contains nuclei for the crystallization of lithium pyrosilicate or lithium metasilicate.

[0136] In particular, the starting glass is prepared by melting a mixture of suitable starting materials, such as carbonates and oxides, at a temperature of approximately 1500 to 1700 °C for 0.5 to 4 hours. To achieve particularly high homogeneity, the obtained glass melt can be poured into water to produce a glass frit, which is then remelted.

[0137] The melt can then be poured into molds, such as steel or graphite molds, to prepare a preform for the starting glass, known as a solid glass preform or a monolithic preform. Typically, these monolithic preforms are then stress-relieved, for example by holding them at 800 to 1200°C for 5 to 60 minutes and then slowly cooling them to room temperature.

[0138] In a preferred embodiment, the melt is poured into water to prepare a frit. This glass frit can be ground into powder or granules. Preferably, if necessary, the resulting powder or granules can be pressed into a preform, a process known as powder compaction, after the addition of other components such as colorants and fluorescent agents.

[0139] First, a further precursor glass with a core can be prepared by heat treatment of the starting glass. Then, a glass-ceramic having several quartz solid solution phases according to the invention can be prepared by heat treatment of this further precursor. Alternatively, a glass-ceramic having multiple quartz solid solution phases according to the invention can be formed by heat treatment of the starting glass.

[0140] Preferably, the starting glass is subjected to heat treatment at a temperature of 400 to 600°C, particularly 450 to 550°C, for a duration preferably of 5 to 120 minutes, particularly 10 to 60 minutes, to prepare a starting glass having a nucleus for crystallization of a multi-quartz solid solution phase.

[0141] Further preferably, the starting glass or a starting glass having a core is subjected to heat treatment at a temperature of 800 to 1000°C, preferably 850 to 950°C, for a duration particularly 1 to 120 minutes, preferably 5 to 120 minutes, and particularly preferably 10 to 60 minutes, to prepare a glass-ceramic having a multi-quartz solid solution phase.

[0142] Therefore, the present invention also relates to a method for preparing glass-ceramics having a multi-quartz solid solution phase according to the invention, wherein a starting glass or a starting glass having a core, particularly in particulate form, preferably in powder form, especially preferably in powder compact form, or a starting glass having a core, is subjected to at least one heat treatment in the range of 800 to 1000°C, preferably 850 to 950°C, for a duration particularly 1 to 120 minutes, preferably 5 to 120 minutes, especially preferably 10 to 60 minutes, and is particularly sintered thereon.

[0143] The at least one heat treatment performed in the method according to the invention can also be carried out during the hot pressing or sintering process of the starting glass according to the invention or the starting glass with a core according to the invention.

[0144] The glass-ceramics and glasses according to the invention are particularly available as powders, granules, or blanks of any shape and size, such as solid blanks, sheets, cubes, or cylinders, or as pressed powder blanks. In these forms, they can be readily further processed, for example, into dental restorations. However, they can also be in the form of dental restorations, such as inlays, onlays, crowns, veneers, facets, or abutment teeth.

[0145] Dental restorations, such as bridges, inlays, high-mounts, crowns, veneers, facets, or abutment teeth, can be prepared from glass-ceramics and glass according to the invention. Therefore, the invention also relates to their use in the preparation of dental restorations. Preferably, the desired shape of the dental restoration is imparted to the glass-ceramic or glass by pressing or machining.

[0146] Pressing is typically carried out under high pressure and high temperature. Preferably, pressing is performed at a temperature of 700 to 1200°C. More preferably, pressing is performed at a pressure of 2 to 10 bar. During pressing, the desired shape change is achieved through the viscous flow of the material used. Starting glasses according to the invention, cored starting glasses according to the invention, and glass-ceramics according to the invention having a multi-quartz solid solution phase can be used for pressing. Specifically, the glasses and glass-ceramics according to the invention can be used in blanks of any shape and size, such as powder compacts, for example in unsintered, partially sintered, or densely sintered forms.

[0147] Machining is typically performed by material removal methods, particularly by milling and / or grinding. Particularly preferred is machining using CAD / CAM methods. The starting glass according to the invention, the cored starting glass according to the invention, and the glass-ceramics according to the invention having a multi-quartz solid solution phase can be machined. For this purpose, the glass and glass-ceramics according to the invention can be used, in particular, in the form of blanks, such as powder compacts, for example, in unsintered, partially sintered, or densely sintered forms.

[0148] After a dental prosthesis has been prepared into the desired shape, for example by pressing or machining, it can still be heat-treated to reduce the porosity of, for example, the porous powder compact used.

[0149] However, the glass-ceramics according to the invention and the glass according to the invention are also suitable as coating materials for, for example, ceramics and glass-ceramics. Therefore, the invention also relates to the use of the glass according to the invention or the glass-ceramics according to the invention for coating, particularly for coating ceramics and glass-ceramics.

[0150] The present invention also relates to a method for coating ceramics, metals, metal alloys and glass ceramics, wherein the glass ceramic or glass according to the invention is applied to the respective substrate and subjected to high temperature.

[0151] This can be accomplished, particularly by sintering on it or by bonding a coating prepared via CAD-CAM using a suitable glass solder or adhesive, and preferably by pressing on it. In the case of sintering on it, the glass ceramic or glass is applied to the material to be coated, such as ceramic or glass ceramic, in a conventional manner, for example as a powder, and then sintered at a high temperature. In the preferred pressing on it, the glass ceramic or glass according to the invention, in the form of a powder compact, is pressed on it at a high temperature, for example, 700 to 1200°C, and under a pressure, for example, 2 to 10 bar. Specifically, the method described in EP231773 and the pressing furnace disclosed therein can be used for this purpose. A suitable furnace is, for example, Programat EP 5000 from Ivoclar Vivadent AG, Liechtenstein.

[0152] Due to the properties described above of the glass-ceramics and glasses according to the invention, they are particularly suitable for use in dentistry. Therefore, another subject of the invention is the use of the glass-ceramics or glasses according to the invention as dental materials, preferably for coating dental restorations, and particularly preferably for preparing dental restorations such as bridges, inlays, high-mount inlays, veneers, abutments, partial crowns, crowns, or facets.

[0153] Therefore, the present invention also relates to a method for preparing dental restorations, particularly bridges, inlays, high inlays, veneers, abutments, partial crowns, crowns or facets, wherein the glass ceramic or glass according to the invention is given the desired shape of the dental restoration by pressing or by machining, particularly by CAD / CAM methods.

[0154] The invention will now be explained in more detail with the aid of non-limiting embodiments. Example

[0155] Examples 1 to 24—Composition and Crystal Phase

[0156] A total of 24 types of glasses and glass ceramics having the compositions shown in Table I according to the present invention were prepared by melting the corresponding starting glass and then subjecting it to controlled crystallization through heat treatment.

[0157] The applied heat treatments are also given in Table I, and the following meanings apply:

[0158] T g Glass transition temperature determined by DSC

[0159] T S and t S Temperature and time applied to melt the starting glass

[0160] T Kb and t Kb Temperature and time applied for nucleation of the starting glass

[0161] T C and t C The temperature and time applied for crystallization.

[0162] T 烧结 and t 烧结 Temperature and time applied during sintering

[0163] T 压制 and t 压制 Temperature and time applied during hot pressing crystallization

[0164] The CR value is determined according to British Standard BS 5612 using the following contrast ratio values ​​for glass ceramics:

[0165] Instrument: CM-3700d spectrometer (Konica-Minolta)

[0166] Measurement parameters:

[0167] Measuring surface: 7 mm × 5 mm

[0168] Measurement type: Remission

[0169] Measurement range: 400 nm - 700 nm

[0170] Sample size:

[0171] Diameter: 15-20 mm

[0172] Thickness: 2 mm + / - 0.025 mm

[0173] Planar parallelism: + / - 0.05 mm

[0174] Surface roughness: approximately 18 μm.

[0175] CTE, according to ISO 6872 (2008), coefficient of thermal expansion of glass ceramics in the range of 100 to 500°C.

[0176] σ 双轴 Biaxial fracture strength as measured according to dental standard ISO 6872 (2008).

[0177] Therefore, firstly, in an air atmosphere in a platinum-rhodium crucible at a temperature T S Starting with melting glass from common raw materials, the duration is t. S .

[0178] In Examples 1 to 23, glass flocs, i.e. glass particles, were prepared by pouring molten starting glass into water. The glass flocs were ground to a particle size of < 45 μm using a ball mill or a grinding mill, and then pressed into powder compacts using a powder press.

[0179] Optionally at temperature T Kb Heat treatment duration t Kb After nucleation, at temperature T 烧结 The duration of powder compaction sintering t 烧结 It becomes a dense body, during which nucleation and crystallization occur simultaneously.

[0180] Therefore, the obtained sintered billet may optionally be subsequently subjected to temperature T 压制 Duration of heat pressing t 压制 To take shape.

[0181] In Example 24, the molten starting glass was cast into a graphite mold to prepare monolithic glass. These monolithic glass pieces were then subjected to temperature T immediately after casting. Kb Below, duration t Kb The first heat treatment is used to form nuclei, followed by slow cooling to room temperature. They are then subjected to temperature T. C Below, duration t C Heat treatment is used to achieve crystallization.

[0182] The meanings in Table I below are:

[0183] QMK: Quartz solid solution

[0184] QMK1: 1. Quartz solid solution phase

[0185] QMK2: 2. Quartz solid solution phase

[0186] LAS: Lithium aluminosilicate (Li2O·Al2O3·7.5SiO2)

[0187] Table I

[0188]

[0189]

[0190]

[0191]

[0192]

[0193]

[0194]

[0195] The glass-ceramic obtained in Example 19 was used with Cu at room temperature. Kα The X-ray diffraction pattern obtained from the X-ray diffraction of the radiation is shown in Figure 1 The characteristic peaks (peak shapes) of the following crystal phases from the PDF-4+ 2020 database (International Data Center for Diffraction) are reproduced below this X-ray diffraction pattern and are labeled with letters A to D:

[0196] A: Low quartz (α-SiO2)

[0197] B: High-quality quartz (β-SiO2)

[0198] C: Lithium pyrosilicate (Li2Si2O5)

[0199] D: Lithium phosphate (Li3PO4)

[0200] In the X-ray diffraction pattern, two quartz solid solution phases can be identified. Compared with the low quartz peak, its peak shape is shifted to a smaller 2θ value, and its highest intensity peaks are at 2θ at 26.5° and 2θ at 26.0°, respectively.

Claims

1. Glass ceramics, comprising the following components Component weight % SiO2 68.0 to 81.0 Li2O 6.0 to 14.0 Al2O3 1.0 to 8.0 And it contains at least two different quartz solid solution phases. The glass-ceramic described herein contains at least two different quartz solid solution phases using Cu Kα The highest intensity reflection peaks in the X-ray powder diffraction of the irradiated material are each in the 2θ range of 25.8 to 26.5°, and when using Cu... Kα The highest intensity reflection peak in the X-ray powder diffraction of the radiation has a 2θ spacing of 0.3 to 0.5°.

2. The glass-ceramic according to claim 1, comprising at least one non-stoichiometric quartz solid solution phase.

3. The glass-ceramic according to claim 2, comprising at least two non-stoichiometric quartz solid solution phases.

4. The glass-ceramic according to claim 1, comprising at least one stoichiometric aluminosilicate crystalline phase.

5. The glass-ceramic according to claim 4, comprising at least two stoichiometric aluminosilicate crystalline phases.

6. The glass-ceramic according to claim 1, comprising at least one non-stoichiometric aluminosilicate crystalline phase.

7. The glass-ceramic according to claim 6, comprising at least two non-stoichiometric aluminosilicate crystalline phases.

8. The glass-ceramic according to claim 1, comprising two different quartz solid solution phases, wherein the two different quartz solid solution phases are used in Cu Kα The highest intensity reflection peak in the X-ray powder diffraction of the radiation has a 2θ spacing of 0.4 to 0.5°.

9. The glass-ceramic according to any one of claims 1 to 8, comprising 70.0 to 79.0% by weight of SiO2.

10. The glass-ceramic according to claim 9, comprising 73.0 to 76.0% by weight of SiO2.

11. The glass-ceramic according to any one of claims 1 to 8, comprising 7.5 to 13.0% by weight of Li2O.

12. The glass-ceramic according to claim 11, comprising 9.0 to 12.0% by weight of Li2O.

13. The glass-ceramic according to any one of claims 1 to 8, comprising 2.0 to 6.5% by weight of Al2O3.

14. The glass-ceramic according to claim 13, comprising 3.0 to 6.0% by weight of Al2O3.

15. The glass-ceramic according to any one of claims 1 to 8, comprising 1.0 to 7.0% by weight of P2O5.

16. The glass-ceramic of claim 15, comprising 2.5 to 5.0% by weight of P2O5.

17. The glass-ceramic of claim 15, comprising 3.0 to 4.4% by weight of P2O5.

18. The glass-ceramic according to any one of claims 1 to 8, comprising 1.0 to 8.0% by weight of an oxide of a monovalent element selected from K₂O, Na₂O, Rb₂O, Cs₂O, and mixtures thereof. I 2O.

19. The glass-ceramic according to claim 18, comprising 1.0 to 5.5% by weight of an oxide of a monovalent element selected from K₂O, Na₂O, Rb₂O, Cs₂O, and mixtures thereof. I 2O.

20. The glass-ceramic according to claim 18, comprising 1.5 to 2.5% by weight of an oxide of a monovalent element selected from K₂O, Na₂O, Rb₂O, Cs₂O, and mixtures thereof. I 2O.

21. The glass ceramic according to any one of claims 1 to 8, comprising 0 to 5.0% by weight of K2O.

22. The glass-ceramic of claim 21, comprising 1.0 to 3.5% by weight of K2O.

23. The glass-ceramic according to claim 21, comprising 1.5 to 2.5% by weight of K2O.

24. The glass-ceramic according to any one of claims 1 to 8, comprising 0 to 9.0% by weight of an oxide of a divalent element selected from CaO, MgO, SrO, ZnO, and mixtures thereof. II O.

25. The glass-ceramic according to claim 24, comprising 2.0 to 8.0% by weight of an oxide of a divalent element selected from CaO, MgO, SrO, ZnO, and mixtures thereof. II O.

26. The glass-ceramic according to claim 24, comprising 3.0 to 7.0% by weight of an oxide of a divalent element selected from CaO, MgO, SrO, ZnO, and mixtures thereof. II O.

27. The glass ceramic according to any one of claims 1 to 8, comprising 0 to 6.0% by weight of MgO.

28. The glass-ceramic of claim 27, comprising 0.1 to 6.0% by weight of MgO.

29. The glass-ceramic of claim 27, comprising 1.0 to 5.5% by weight of MgO.

30. The glass-ceramic of claim 27, comprising 2.0 to 5.0% by weight of MgO.

31. The glass-ceramic according to claim 27, comprising 2.5 to 4.5% by weight of MgO.

32. The glass-ceramic according to claim 27, comprising 3.0 to 4.0% by weight of MgO.

33. The glass-ceramic according to any one of claims 1 to 8, comprising 0 to 5.0% by weight of an oxide of a trivalent element selected from B₂O₃, Y₂O₃, La₂O₃, Ga₂O₃, In₂O₃, and mixtures thereof. III 2O3.

34. The glass-ceramic according to claim 33, comprising 1.0 to 4.0% by weight of an oxide of a trivalent element selected from B₂O₃, Y₂O₃, La₂O₃, Ga₂O₃, In₂O₃, and mixtures thereof. III 2O3.

35. The glass-ceramic according to claim 33, comprising 2.0 to 3.0% by weight of an oxide of a trivalent element selected from B₂O₃, Y₂O₃, La₂O₃, Ga₂O₃, In₂O₃, and mixtures thereof. III 2O3.

36. The glass-ceramic according to any one of claims 1 to 8, comprising SiO2 and Li2O in a molar ratio ranging from 2.2 to 6.

0.

37. The glass-ceramic according to claim 36, comprising SiO2 and Li2O in a molar ratio ranging from 2.8 to 5.

0.

38. The glass-ceramic according to claim 36, comprising SiO2 and Li2O in a molar ratio ranging from 3.0 to 4.

0.

39. The glass-ceramic according to any one of claims 1 to 8, comprising lithium pyrosilicate or lithium metasilicate as the main crystalline phase.

40. The glass-ceramic according to claim 39, comprising lithium pyrosilicate as the main crystalline phase.

41. The glass-ceramic according to any one of claims 1 to 8, comprising at least 20% by weight of lithium pyrosilicate crystals.

42. The glass-ceramic according to claim 41, comprising 25 to 55% by weight of lithium pyrosilicate crystals.

43. The glass-ceramic according to claim 41, comprising 30 to 55% by weight of lithium pyrosilicate crystals.

44. The glass-ceramic according to any one of claims 1 to 8, comprising 0.2 to 28% by weight of a quartz solid solution phase.

45. The glass-ceramic according to claim 44, comprising 0.2 to 25% by weight of a quartz solid solution phase.

46. ​​A starting glass comprising the components of a glass-ceramic according to any one of claims 1 to 38.

47. The starting glass of claim 46, comprising nuclei for the crystallization of two different quartz solid solution phases.

48. The starting glass of claim 47, further comprising a nucleus for crystallization of lithium pyrosilicate or lithium metasilicate.

49. The glass-ceramic according to any one of claims 1 to 8 or the starting glass according to any one of claims 46 to 48, wherein the glass-ceramic and the starting glass are in the form of powder, granules, blanks or dental restorations.

50. A method for preparing glass-ceramics according to any one of claims 1 to 45, wherein the starting glass according to any one of claims 46 to 48 is subjected to at least one heat treatment in the range of 800°C to 1000°C.

51. The method of claim 50, wherein the starting glass according to any one of claims 46 to 48 is in granular form.

52. The method of claim 50, wherein the starting glass according to any one of claims 46 to 48 is in powder form.

53. The method of claim 50, wherein the starting glass according to any one of claims 46 to 48 is in the form of a powder compact.

54. The method of claim 50, wherein the heat treatment is a heat treatment in the range of 850°C to 950°C.

55. The method of claim 50, wherein the heat treatment comprises sintering the starting glass according to any one of claims 46 to 48.

56. Use of the glass-ceramic according to any one of claims 1 to 45 or 49, or the starting glass according to any one of claims 46 to 49, as a dental material.

57. The use according to claim 56, wherein the glass ceramic or the starting glass is used to coat a dental restoration.

58. The use according to claim 56, wherein the glass-ceramic or the starting glass is used to prepare dental restorations.

59. Use according to claim 58 for preparing dental restorations, wherein the glass-ceramic or the starting glass is given the desired shape of the dental restoration by pressing or machining.

60. The use of the dental restoration according to claim 59, wherein the dental restoration is a bridge, inlay, high inlay, veneer, abutment tooth, partial crown, crown or facet.

61. A method for preparing a dental prosthesis, wherein the desired shape of the dental prosthesis is imparted by pressing or machining to the glass-ceramic or the starting glass according to any one of claims 1 to 45 or 49.

62. The method according to claim 61, wherein the dental restoration is a bridge, inlay, high inlay, veneer, abutment tooth, partial crown, crown or facet.

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