PROCESS FOR PREPARING A GLASS-CERAMIC BODY

• US 20140141960A1
• Filed: 04/20/2012
• Published: 05/22/2014
• Est. Priority Date: 04/20/2011
• Status: Active Grant

• Current Assignee: Straumann Holding AG
• Original Assignee: Straumann Holding AG
• Inventors: Borczuch-Laczka, Maria, Cholewa-Kowalska, Katharzyna, Laczka, Karolina
• Granted Patent: US 9,260,342 B2
• Time in Patent Office: Days
• US Class Current: 501/32
• CPC Class Codes: A61K 6/816 comprising titanium oxide
• CPC Class Codes: A61K 6/818 comprising zirconium oxide
• CPC Class Codes: A61K 6/822 comprising rare earth metal oxides
• CPC Class Codes: A61K 6/824 comprising transition metal oxides
• CPC Class Codes: A61K 6/833 Glass-ceramic composites
• CPC Class Codes: C03B 32/02 Thermal crystallisation, e.g. for crystallising glass bodies into glass-ceramic articles C03B27/012 takes precedence
• CPC Class Codes: C03C 10/0027 containing SiO2, Al2O3, Li2O as main constituents
• CPC Class Codes: C03C 23/0005 by irradiation
• CPC Class Codes: C03C 23/0025 by a laser beam
• CPC Class Codes: C03C 3/083 containing aluminium oxide or an iron compound
• CPC Class Codes: C03C 3/097 containing phosphorus, niobium or tantalum
• CPC Class Codes: C03C 4/0021 for dental use

Abstract

Process for preparing glass-ceramic body including the steps of providing a basic glass body and subjecting the basic glass body to a thermal treatment whereby a crystalline phase embedded in a glass matrix is formed. The basic glass body is made of a composition comprising 65 to 72 wt-% SiO₂, at least 10.1 wt-% Li₂O and at least 10.1 wt-% Al₂O₃ based on the total weight of the composition, the proportion of Li₂O to Al₂O₃ being from 1:1 to 1.5:1. The thermal treatment involves a nucleation step followed by several crystallization steps at different temperatures, whereby at least two different crystalline phases are formed.

Claims

1. Process for preparing a glass-ceramic body comprising the steps of providing a basic glass body and subjecting the basic glass body to a thermal treatment whereby a crystalline phase embedded in a glass matrix is formed,

wherein the basic glass body is made of a composition comprising 65 to 72 wt-% SiO2, at least 10.1 wt-% Li2O and at least 10.1 wt-% Al2O3 based on the total weight of the composition, the proportion of Li2O to Al2O3 being from 1:

1 to 1.5;

1, and the thermal treatment involves a nucleation step followed by a first crystallization step at a first temperature range and a second crystallization step at a second temperature range different from the first temperature range, wherein at least two different crystalline phases are formed.

2. Process for preparing a glass-ceramic body according to claim 1, wherein a first region of the glass body is subjected to the first crystallization step and a second region of the glass body different to the first region is subjected to the second crystallization step such that the proportion of the first crystalline phase is higher in the first region than in the second region and the proportion of the second crystalline phase is higher in the second region than in the first region.

3. Process according to claim 2, wherein the regions are heated to the respective temperature ranges by means of laser irradiation, electromagnetic radiation and/or susceptors.

4. Process according to any of the claim 1, wherein the first temperature range is from 620 to 820°

C. and the second temperature range is starting from 825°

C.

5. Glass composition comprising 65 to 72 wt-% SiO2, at least 10.1 wt-% Li2O and at least 10.1 wt-% Al2O3 based on the total weight of the composition, the proportion of Li2O to Al2O3 being from 1:

1 to 1.5;

1.

6. Glass composition according to claim 5, comprising at most 15 wt-% of Li2O and/or at most 15 wt-% of Al2O3.

7. Glass composition according to any of claim 5, further comprising 0 to 2 wt-% K2O, 1 to 4 wt-% Na2O, 0 to 1.5 wt-% CaO, 0 to 1.0 wt-% MgO, 0 to 1.5 wt-% B2O3, 0 to 1.5 wt-% CeO2, 1 to 5 wt-% P2O5, 0 to 3 wt-% CaF2, 0 to 2.0 wt-% AlF3, 0 to 1.0 wt-% Ag, 0 to 5 wt % ZrO2 and 0 to 4 wt-% TiO2 based on the total weight of the composition.

8. Glass composition according to any of claim 5, further comprising 0 to 2 wt-% K2O, at most 4 wt-% Na2O, 0 to 1.5 wt-% CaO, 0 to 1.5 wt-% CeO2, 1 to 5 wt-% P2O5, 0 to 0.5 wt-% V2O5, 0 to 1 wt-% Ag and 0 to 1 wt % ZrO2, the composition being devoid of TiO2, Cu2O, BaO, Sb2O3, Nb2O5, MgO, La2O3 and SnO2.

9. Glass composition according to any of claim 5, essentially consisting of 0 to 2 wt-% K2O, at most 4 wt-% Na2O, 0 to 1.5 wt-% CaO, 0 to 1.5 wt-% CeO2, 1 to 5 wt-% P2O5, 0 to 0.05 wt-% V2O5, 0 to 1 wt-% Ag and 0 to 1 wt % ZrO2 besides SiO2, Li2O and Al2O3.

10. Glass-ceramic body comprising at least two crystalline phases selected from the group consisting of Li2SiO3, Li2Si2O5, LiAlSi2O6, LiAlSiO4, LiAlSi3O8, LiAlSi4O10 and Li3PO4.

11. Glass-ceramic body according to claim 10 comprising

a) a first crystalline phase of Li2Si2O5 and

b) a second crystalline phase selected from the group consisting of LiAlSi2O6, LiAlSiO4, LiAlSi3O8 and LiAlSi4O10.

12. Glass-ceramic body according to claim 11 comprising a first region and a second region different to the first region, wherein in the first region the proportion of the first crystalline phase is higher than in the second region and in the second region the proportion of the second crystalline phase is higher than in the first region.

13. Glass-ceramic body according to claim 12, wherein the first crystalline phase and the second crystalline phase change gradually from region to region.

14. Glass-ceramic body according to claim 12, the glass-ceramic body being in the form of a dental restoration having an enamel area and a dentin area corresponding to the respective areas of a natural tooth, with the first region being arranged in the enamel area and the second region being arranged in the dentin area.

15. Method of forming a dental restoration comprising forming a dental restoration from the glass-ceramic body of claim 10.