Sol containing nano zirconia particles for use in additive manufacturing processes for the production of 3-dimensional articles

Patent metadata

Field	Value
Publication number	US-11339095-B2
Application number	US-201615574646-A
Country	US
Kind code	B2
Filing date	May 26, 2016
Priority date	May 28, 2015
Publication date	May 24, 2022
Grant date	May 24, 2022

Abstract

The invention relates to the use of a printing sol as construction material in an additive manufacturing process for producing a 3-dim article, the printing sol comprising solvent(s), nano-sized crystalline zirconia particles in an amount from 2 to 25 vol.-% with respect to the volume of the sol, the average primary particle size of the nano-sized crystalline zirconia particles being in a range up to 50 nm, a first monomer being a polymerizable surface modification agent represented by formula A-B, with A being capable of attaching to the surface of the nano-sized crystalline zirconia particles and B being a radiation curable group, optionally a second monomer, the second monomer comprising at least one radiation curable moiety but no acidic or silane group(s), photo initiator(s). The invention also relates to a ceramic article obtainable according to such a process.

First claim

The invention claimed is:

1. A printing sol as construction material in an additive manufacturing process for producing a three-dimensional article, the printing sol comprising:
solvent(s);
nano-sized crystalline zirconia particles in an amount from 2 to 25 vol.-% with respect to the volume of the sol, the average primary particle size of the nano-sized crystalline zirconia particles being in a range up to 20 nm;
a first monomer being a polymerizable surface modification agent represented by formula A-B, with A being capable of attaching to a surface of the nano-sized crystalline zirconia particles and B being a radiation curable group;
optionally a second monomer, the second monomer comprising at least one radiation curable moiety but no acidic or silane group(s); and
photoinitiator(s),
wherein the solvent(s), the nano-sized crystalline zirconia particles, the first monomer, optionally the second monomer, and the photoinitiator(s) form a sol,
wherein the printing sol forms the three-dimensional article in a gel body state characterized by a Volume A,
wherein the printing sol forms the three-dimensional article in a sintered state characterized by a Volume F, and
wherein Volume A is more than 200% greater than Volume F.

2. The printing sol of claim 1 , the printing sol being characterized by at least one or all of the following features:
showing a transmission of at least 5% at 420 nm determined for a path length of 10 mm;
the sol having a viscosity of less than 500 mPa*s at 23° C.;
pH value: from 1 to 6 if brought in contact with water.

3. The printing sol of claim 1 , the polymerizable surface modification agent represented by formula A-B being characterized by at least one of the following features:
A comprising an acidic group or a silane group;
B comprising a vinyl group;
being present in the sol in an amount from 2 to 30 wt.-% with respect to the weight of the sol.

4. The printing sol of claim 3 , wherein B is selected from an acryl group and a methacryl group.

5. The printing sol of claim 1 , the nano-sized zirconia particles being characterized by at least one or all of the following features:
being essentially spherical, cuboidal or a mixture thereof;
being non-associated;
comprising ZrO 2 in an amount of 70 to 100 mol-%;
comprising HfO 2 in an amount of 0 to 4.5 mol-%;
comprising a stabilizer selected from Y 2 O 3 , CeO 2 , MgO, CaO, La 2 O 3 or a combination thereof in an amount of 0 to 30 mol-%;

comprising Al 2 O 3 in an amount of 0 to 1 mol-%.

6. The printing sol of claim 1 , the photoinitiator being characterized by at least one or all of the following features:
showing radiation absorbance in the range from 200 to 500 nm;
being combustible without residues at a temperature below 800° C.;
comprising a moiety selected from benzophenone, xanthone, quinone, benzoin ether, acetophenone, benzoyl oxime or acyl phosphine;
being present in the sol in an amount from 0.01 to 3 wt.-% with respect to the weight of the sol.

7. The printing sol of claim 1 , the solvent being characterized by at least one of the following features:
having a boiling point above 70° C.;
having a molecular weight from 25 to 300 g/mol;
having a viscosity from 0.1 to 50 mPa*s at 23° C.

8. The printing sol of claim 7 , the solvent being characterized as having a boiling point above 150° C.

9. The printing sol of claim 1 , the sol further comprising inhibitor(s) in an amount from 0.001 to 0.5 wt.-% with respect to the weight of the sol.

10. The printing sol of claim 1 , the printing sol being characterized as follows:
the solvent(s) in an amount from 25 to 70 wt.-%;
the nano-sized crystalline zirconia particles in an amount from amount from 2 to 25 vol.-%;
one or more of the first monomer and the second monomer present in an amount totaling from 2 to 30 wt.-%;

the photoinitiator in an amount from 0.001 to 3 wt.-%;
an inhibitor in an amount from 0 to 0.5 wt.-%;
wt.-% and vol.-% with respect to the weight or volume of the printing sol.

11. A process for producing a ceramic article, the process comprising:
providing a printing sol as described in claim 1 ;
processing the printing sol as construction material in an additive manufacturing process to obtain a 3-dim article being in a gel state, the 3-dim article in a gel state having a Volume A;
transferring the 3-dim article being in a gel state to a 3-dim article being in a dry state selected from an aerogel and a xerogel;
applying a heat treatment step to obtain a sintered 3-dim ceramic article, the sintered ceramic article having a Volume F
wherein Volume A is more than 200% greater than Volume F.

12. The process of claim 11 , wherein Volume A is at least 500% greater than Volume F.

13. The process of claim 11 , the process further comprising:
additive manufacturing desired geometries by sequential light curing of layers to obtain a 3-dim article being in a gel state;
optionally cleaning a surface of the 3-dim article being in a gel state;
optionally post-curing the 3-dim article being in a gel state to a temperature in the range of 35 to 80° C. or by additional light hardening to form a post-cured 3-dim article characterized by a Volume B;
optionally soaking the 3-dim article being in a gel state with a solvent;
applying a supercritical drying step to the 3-dim article being in a gel state to form a 3-dim article being in a dry state as an aerogel characterized by a Volume C;
optionally heating the 3-dim article being in a dry state as an aerogel to a temperature in the range of 400 to 800° C. to form a green body characterized by a Volume D;
optionally heating the green body to a temperature in the range of 800 to 1100° C. to form a pre-sintered body or a white body having a porous structure, the pre-sintered body or white body characterized by a Volume E;
optionally coloring at least a part of a surface of the pre-sintered body or white body;
applying the heat treatment step to obtain the sintered 3-dim ceramic article characterized by the Volume F.

14. The process of claim 11 , wherein the processing of the printing sol comprises one or more of the following parameters:
slice thickness of printing sol exposed to radiation: 0.001 to 0.500 mm;
energy dose per layer in the range of 5 mJ/cm 2 to 100 mJ/cm 2 .

15. The process of claim 11 , the process excluding one or more of the following:
heating the construction material during the processing step to a temperature above 70° C.;
applying pressure during the heat treatment step.

16. The process of claim 11 , the sintered 3-dim ceramic article being characterized by at least one of the following features:
density: more than 98.5% with respect to theoretical density;
translucency: more than 30% determined on a polished sample having a thickness of 1 mm;
flexural strength: at least 450 MPa according to ISO 6872;
phase content tetragonal phase: from 0 to 100 wt.-%;
phase content cubic phase: from 0 to 100 wt.-%;
size in either x, y or z direction: at least 0.25 mm.

17. The process of claim 16 , the sintered 3-dim ceramic article having a shape of a dental restoration or orthodontic bracket.

Assignees

• 3M Innovative Properties Co

Inventors

• Mayr Helmar B
• Korten Malte
• Andres Christine M
• Kolb Brant U
• Hauptmann Holger
• Schechner Gallus
• Jahns Michael
• Humpal Kathleen M
• Lackey Melissa A
• Pennington Paul D

Classifications

• B33Y70/10

  Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials · CPC title

• A61C13/0019

  using three dimensional printing · CPC title

• A61C13/09

  {Composite teeth, e.g. front and back section (A61C13/0835, A61C13/1023 take precedence)}; Multilayer teeth · CPC title

• A61K6/82

  comprising hafnium oxide · CPC title

• A61K6/807

  comprising magnesium oxide · CPC title