Spinel glass ceramic, method for its manufacture and shaped dental product containing the spinel glass ceramic

Description

[0001] The present invention relates to a spinel glass-ceramic composed of the following components: 25 to 50 wt% SiO₂, 10 to 35 wt% Al₂O₃, 1 to 15 wt% MgO, 1 to 15 wt% P₂O₅, 1 to 25 wt% ZrO₂ and / or TiO₂, 0.1 to 20 wt% La₂O₃, 0 to 10 wt% B₂O₃, and 0 to 15 wt% additives. The spinel glass-ceramic contains at least one spinel phase, but no high-quartz solid solution phase. The glass-ceramic according to the invention exhibits very high mechanical stability, e.g., very high flexural strength, while its optical properties are simultaneously adjustable. Furthermore, the present invention relates to a method for producing and using the spinel glass-ceramic. The present invention also relates to a shaped dental product containing the spinel glass-ceramic.

[0002] High-strength glass ceramics are of diverse interest. Particularly in dentistry, high-strength, translucent glass ceramics are required for larger restorations, such as three-unit or multi-unit bridges in the molar region. The glass ceramics with the highest flexural strengths on the market are derived from the lithium silicate system. Such glass ceramics are described, for example, in EP 1 688 397, US 2017 / 267575, or EP 2 723 303 and exhibit maximum flexural strengths of up to 400 MPa (3-point flexural strength according to DIN EN ISO 6872).

[0003] Furthermore, glass ceramics based on the high-quartz solid solution system are known from the prior art. However, these glass ceramics, described for example in US 2016 / 0051451 A1, have not become established because they cannot compete with the lithium silicate glass ceramics currently on the market in terms of their optical / translucency and mechanical properties.

[0004] WO 2014 / 161770 A1 concerns magnesium oxide-aluminum oxide-silicon oxide glass or glass-ceramics based on the high-quartz solid solution system, which are easily machined in an intermediate crystallization stage and, after complete crystallization, represent a high-strength, highly translucent, and chemically stable glass-ceramic. The glasses or ceramics are characterized by the fact that they also contain phosphorus and a transition metal component, selected from titanium and zirconium or a mixture of both.

[0005] In his dissertation "The Influence of P₂O₅ on the Structure and Properties of Glasses and Glass Ceramics of the MgO-Al₂O₃-SiO₂ System," Axel Katzschmann, Friedrich Schiller University Jena, investigated the influence of P₂O₅ on the structure and properties of glasses and glass ceramics of the MgO-Al₂O₃-SiO₂-(TiO₂) system. The work focused on the chemical and physical characterization of the modified glasses and glass ceramics, as well as investigations into the influence of P₂O₅ on the phase separation, nucleation, and crystallization behavior of the glasses.

[0006] For applications, particularly dental ones, where flexural strengths exceeding 400 MPa are required, there is currently no viable solution from the glass-ceramic sector. Instead, sinterable nano-zirconium oxide ceramics are used in dentistry, for example, but these are not comparable to glass-ceramics, especially in terms of their optical properties.

[0007] Based on this, the object of the present invention was to provide a glass ceramic which has very high mechanical stability, in particular very high flexural strength, and at the same time advantageous optical properties.

[0008] This problem is solved with respect to a spinel glass-ceramic with the features of claim 1, with respect to a method for producing a spinel glass-ceramic with the features of claim 8, and with respect to a shaped dental product containing the spinel glass-ceramic with the features of claim 12. The respective dependent claims represent advantageous embodiments.

[0009] According to the invention, a spinel glass ceramic is thus specified, consisting of a composition with the following components: 25 to 50 wt% SiO₂, 10 to 35 wt% Al₂O₃, 1 to 15 wt% MgO, 1 to 15 wt% P₂O₅, 1 to 25 wt% ZrO₂ and / or TiO₂, 0.1 to 20 wt% La₂O₃, 0 to 10 wt% B₂O₃, and 0 to 15 wt% additives. the proportions of the components are complementary to 100 wt.%.

[0010] According to the invention, a spinel glass ceramic is understood to be a glass ceramic that contains at least one spinel phase (or spinel crystal phase).

[0011] Spinel preferably refers to magnesium spinel (e.g., with the composition MgAl₂O₄). Particularly preferably, the spinel is a magnesium-aluminum spinel, e.g., with the composition MgAl₂(2+x)O₄(4+1.5x), where x is a number from 0 to 1.

[0012] The spinel glass-ceramic according to the invention does not contain a high-quartz solid solution phase. Furthermore, the spinel glass-ceramic according to the invention has a lanthanum phosphate crystal phase.

[0013] The glass-ceramic according to the invention is characterized by its special composition. Due to this composition and the special manufacturing process of the glass-ceramic via a two-stage heat treatment, the glass-ceramic contains at least one spinel crystal phase, but no high-quartz solid solution phase. Because of the presence of this spinel crystal phase, the glass-ceramic exhibits very high mechanical strength and can therefore also be used in applications requiring particularly high mechanical strength. For example, flexural strengths of over 400 MPa (measured according to DIN EN ISO 6872) can be achieved with the glass-ceramic according to the invention when produced in small batches. Thus, the system has enormous potential for homogeneous production in larger batches, as experience has shown that the strength can increase by approximately 100 MPa in this case.

[0014] Furthermore, the glass-ceramic according to the invention exhibits particularly advantageous optical properties. For example, the optical properties of the glass-ceramic can be adjusted from highly translucent to opaque. In other words, the spinel glass-ceramic according to the invention can be obtained as a highly translucent glass-ceramic, as an opaque glass-ceramic, or in many intermediate stages.

[0015] A preferred embodiment of the spinel glass ceramic according to the invention is characterized in that the spinel glass ceramic consists of a composition with the following components: 30 to 45 wt.%, preferably 33.5 to 45 wt.%, particularly preferably 35 to 40 wt.% SiO₂, 15 to 30 wt.%, preferably 20 to 25 wt.% Al₂O₃, 3 to 10 wt.%, preferably 5 to 8 wt.% MgO, 2 to 10 wt.%, preferably 3 to 8 wt.% P₂O₅, 8 to 20 wt.%, preferably 12 to 18 wt.% ZrO₂ and / or TiO₂, 0.1 to 15 wt.%, preferably 8 to 12 wt.% La₂O₃, 0.1 to 5.0 wt.%, preferably 1.0 to 2.0 wt.% B₂O₃, and 0.1 to 10.0 wt.%, preferably 1.0 to 8.0 wt.% additives.

[0016] Preferably, the composition of the spinel glass ceramic contains 33.5 to 50 wt.%, particularly preferably 34.0 to 50 wt.%, most preferably 34.5 to 50 wt.%, in particular 35.0 to 50 wt.%, SiO 2 .

[0017] According to the invention, the spinel glass-ceramic composition contains both 1 to 15 wt% P₂O₅ and 0.1 to 20 wt% La₂O₃. The spinel glass-ceramic may contain spinel and lanthanum phosphate. Preferably, the spinel glass-ceramic does not contain monazite.

[0018] Another preferred embodiment of the spinel glass-ceramic according to the invention is characterized in that the spinel glass-ceramic has spinel as the main crystal phase. The glass-ceramic according to the invention can thus preferably have a spinel phase as the main crystal phase. A "main crystal phase" is preferably understood to be the crystal phase of the glass-ceramic that has the highest mass fraction of all the crystal phases present in the glass-ceramic. Alternatively, the glass-ceramic can also have several (e.g., two) main crystal phases, wherein these main crystal phases then have higher mass fractions than the other crystal phases present in the glass-ceramic. In this case, the glass-ceramic can thus have, for example, a second main crystal phase in addition to spinel as the main crystal phase.

[0019] Preferably, the proportion of the main spinel crystal phase to all crystal phases present in the spinel glass ceramic is at least 30 wt.%, particularly preferably at least 50 wt.%.

[0020] In addition to spinel, the glass ceramic according to the invention can have several other crystal phases. The spinel glass ceramic according to the invention has a lanthanum phosphate crystal phase. Due to the presence of both a spinel phase (or spinel crystal phase) and a lanthanum phosphate crystal phase in the glass ceramic, the glass ceramic exhibits particularly high mechanical strength.

[0021] In a further preferred embodiment of the spinel glass ceramic according to the invention, the additives are selected from the group consisting of fluorine, sodium oxide, barium oxide, strontium oxide, zinc oxide, calcium oxide, yttrium oxide, niobium oxide, tantalum oxide, lanthanum oxide, nucleating agents, in particular tin oxide and / or precious metals, fluorescent agents, dyes, auxiliary substances, and mixtures thereof.

[0022] It is preferred that the fluorescent agents are selected from the group consisting of oxides of neodymium, praseodymium, samarium, europium, terbium, dysprosium, holmium, erbium, and mixtures thereof.

[0023] Furthermore, it is preferred that the dyes are selected from the group consisting of glass-coloring oxides, preferably oxides of iron, titanium, cerium, copper, chromium, cobalt, nickel, manganese, selenium, silver, indium, gold and oxides of rare earth metals, coloring bodies, preferably doped spinels, and mixtures thereof.

[0024] Another preferred embodiment of the spinel glass ceramic according to the invention is characterized in that the spinel glass ceramic has a flexural strength, measured according to DIN EN ISO 6872, of more than 400 MPa, preferably more than 500 MPa.

[0025] The present invention also relates to a method for producing the spinel glass ceramic according to the invention in which a) a starting glass is produced which contains the components of the spinel glass ceramic, b) the starting glass is subjected to at least one first heat treatment and subsequently to at least one second heat treatment.

[0026] In a preferred embodiment of the method according to the invention, the at least one first heat treatment takes place at a temperature of 700 °C to 950 °C, preferably from 800 °C to 900 °C, and / or over a period of 15 min to 360 min, preferably from 120 min to 240 min.

[0027] Furthermore, it is preferred that the at least one second heat treatment takes place at a temperature of 900 °C to 1200 °C, preferably from 950 °C to 1000 °C, and / or over a period of 5 min to 200 min, preferably from 60 min to 120 min.

[0028] Furthermore, the present invention relates to the use of the spinel glass-ceramic according to the invention as a dental material, as a component of a dental material, or as a high-strength substrate for components, in particular electronic components. For example, the spinel glass-ceramic according to the invention can be used in a molar bridge.

[0029] The present invention further relates to a shaped dental product containing a spinel glass ceramic according to the invention, in particular in the form of an inlay, an onlay, a bridge, e.g. a molar bridge, a post and core, a veneer, a crown or a partial crown.

[0030] The following examples are intended to explain the present invention in more detail, without limiting it to the specific embodiments and parameters shown here. Examples of implementation

[0031] In a first embodiment, a starting glass with the following composition is first produced: 38.25 wt.% SiO2, 22.15 wt.% Al2O3, 6.51 wt.% MgO, 7.06 wt.% P2 O5, 7.66 wt.% ZrO2, 4.97 wt.% TiO2, 11.75 wt.% La2 O3, 1.64% by weight B 2 O 3 .

[0032] The starting glass undergoes a first heat treatment at 900 °C for 2 hours, followed by a second heat treatment at 1000 °C for 2 hours. This yields a spinel glass-ceramic according to the invention, exhibiting a maximum flexural strength of 546 MPa, measured according to DIN EN ISO 6872. X-ray diffraction and TEM examination of the produced glass-ceramic revealed that it contains a spinel phase (or spinel crystal phase) and a lanthanum phosphate crystal phase, but no high-quartz solid solution phase.

[0033] In a second embodiment, a starting glass with the following composition is first produced: 35.01 wt.% SiO2, 23.80 wt.% Al2O3, 5.23 wt.% MgO, 3.26 wt.% P2 O5, 8.83 wt.% ZrO2, 6.76 wt.% TiO2, 11.24 wt.% La2 O3, 1.57 wt.% B 2 O 3 , 1.80 wt.% CeO 2 , 2.00 wt.% Y 2 O 3 , 0.50 wt.% Tb 5 O 11 .

[0034] The starting glass undergoes a first heat treatment, which takes place at a temperature of 800 °C for a period of 4 hours, and then a second heat treatment, which takes place at a temperature of 985 °C for a period of 1 hour.

[0035] A spinel glass-ceramic according to the invention is obtained, which exhibits a maximum flexural strength of 433 MPa, measured according to DIN EN ISO 6872. Investigation of the produced glass-ceramic by X-ray diffractometry and TEM revealed that it contains a spinel phase (or spinel crystal phase) and a lanthanum phosphate crystal phase, but no high-quartz solid solution phase.

Claims

1. Spinel glass-ceramic having a composition with the following components: 25 to 50% by weight SiO2, 10 to 35% by weight Al2O3, 1 to 15% by weight MgO, 1 to 15% by weight P2O5, 1 to 25% by weight ZrO2 and / or TiO2, 0.1 to 20% by weight La2O3, 0 to 10% by weight B2O3, and 0 to 15% by weight additives, the proportions of the components adding up to 100% by weight, wherein the spinel glass-ceramic is a glass-ceramic containing at least one spinel phase, wherein the spinel glass-ceramic comprises a lanthanum phosphate crystal phase, and the spinel glass-ceramic not containing any high quartz solid solution phase.

2. The spinel glass-ceramic according to the preceding claim, having a composition with the following components: 30 to 45% by weight, preferably 35 to 40% by weight SiO2, 15 to 30% by weight, preferably 20 to 25% by weight Al2O3, 3 to 10% by weight, preferably 5 to 8% by weight MgO, 2 to 10% by weight, preferably 3 to 8% by weight P2O5, 8 to 20% by weight, preferably 12 to 18% by weight ZrO2 and / or TiO2, 0.1 to 15% by weight, preferably 8 to 12% by weight La2O3, 0.1 to 3.0% by weight, preferably 1.0 to 2.0% by weight B2O3, and 0.1 to 10.0% by weight, preferably 1.0 to 8.0% by weight additives.

3. Spinel glass-ceramic according to any one of the preceding claims, characterized in that the spinel glass-ceramic has spinel as the main crystal phase, wherein the proportion of the spinel main crystal phase in all crystal phases present in the spinel glass ceramic is preferably at least 30% by weight, particularly preferably at least 50% by weight, very particularly preferably at least 70% by weight.

4. Spinel glass-ceramic according to any one of the preceding claims, characterized in that the additives are selected from the group consisting of fluorine, sodium oxide, barium oxide, strontium oxide, zinc oxide, calcium oxide, yttrium oxide, niobium oxide, tantalum oxide, lanthanum oxide, nucleating agents, in particular tin oxide and / or precious metals, fluorescent agents, dyes, auxiliaries, and mixtures thereof.

5. Spinel glass-ceramic according to the preceding claim, characterized in that the fluorescent agents are selected from the group consisting of oxides of neodymium, praseodymium, samarium, europium, terbium, dysprosium, holmium, erbium, and mixtures thereof.

6. Spinel glass-ceramic according to any one of claims 4 or 5, characterized in that the dyes are selected from the group consisting of - glass-coloring oxides, preferably oxides of iron, titanium, cerium, copper, chromium, cobalt, nickel, manganese, selenium, silver, indium, gold and oxides of rare earth metals - color bodies, preferably doped spinels, and - mixtures thereof.

7. Spinel glass-ceramic according to any one of the preceding claims, characterized in that the spinel glass-ceramic has a flexural strength, measured according to DIN EN ISO 6872, of more than 400 MPa, preferably more than 500 MPa.

8. Method for producing a spinel glass-ceramic according to any one of the preceding claims in which a) a starting glass containing the components of the spinel glass-ceramic is produced, b) the starting glass is subjected to at least one first heat treatment and then to at least one second heat treatment.

9. Method according to the preceding claim, characterized in that the at least one first heat treatment takes place at a temperature of 700°C to 950°C, preferably from 800°C to 900°C, and / or over a period of 15 min to 360 min, preferably 120 min to 240 min.

10. Method according to any one of claims 8 or 9, characterized in that the at least one second heat treatment takes place at a temperature of 900°C to 1200°C, preferably from 950°C to 1000°C, and / or over a period of 5 min to 200 min, preferably of 60 min to 120 min.

11. Use of a spinel glass-ceramic according to any one of claims 1 to 7 as a dental material, as a component of a dental material or as a high-strength substrate for components, in particular electronic components.

12. Shaped dental product containing a spinel glass-ceramic according to any one of claims 1 to 7, in particular in the form of an inlay, an onlay, a bridge, a pin structure, a facing, a crown or a partial crown.