Additive manufacturing process for producing ceramic articles using a sol containing nano-sized particles

Patent metadata

Field	Value
Publication number	US-2018148378-A1
Application number	US-201615574630-A
Country	US
Kind code	A1
Filing date	May 18, 2016
Priority date	May 28, 2015
Publication date	May 31, 2018
Grant date	—

Abstract

The present invention relates to a process for producing a ceramic article, the process comprising the steps of providing a printing sol, the printing sol comprising solvent, nano-sized particles, radiation curable monomer(s) and photoinitiator, the printing sol having a viscosity of less than 500 mPa*s at 23° C., 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 having a Volume A, transferring the 3-dim article being in a gel state to a 3-dim article being in an aerogel state, heat treating the 3-dim article to obtain a sintered 3-dim ceramic article, the ceramic article having a Volume F, Volume A of the 3-dim article in a gel state being more than 500% of Volume F of the ceramic article in its sintered state. The invention also relates to a ceramic article obtainable according to such a process. The ceramic article can have the shape of a dental or orthodontic article.

First claim

1 . A process for producing a ceramic article, the process comprising:
providing a printing sol, wherein the printing sol comprising solvent, nano-sized particles, radiation curable monomer(s) and photoinitiator, and wherein the printing sol having a viscosity of less than 500 mPa*s at 23° C.; 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 having a Volume A, transferring the 3-dim article being in a gel state to a 3-dim article being in a dry state, namely an aerogel or xerogel; and applying a heat treatment step to obtain a sintered 3-dim ceramic article, the ceramic article having a Volume FL;
wherein Volume A of the 3-dim article in a gel state being more than 500% of Volume F of the ceramic article in its sintered state.

2 . The process of claim 1 , the transfer of the 3-dim article being in a gel state to a 3-dim article being in a dry state being conducted by applying a supercritical drying step.

3 . The process according to of claim 1 , the additive manufacturing process being selected from: stereolithographic printing.

4 . The process according to of claim 1 , the additive manufacturing processing comprising the steps of:
providing a layer of the construction material on a surface; radiation curing those parts of the layer of construction material which will belong to the 3-dim article to be produced; providing an additional layer of the construction material in contact with the radiation cured surface of the previous layer; and repeating the previous steps until the 3-dim article is obtained.

5 . The process of claim 1 , the process not comprising either or all of the following steps:
heating the construction material during the additive manufacturing processing step to a temperature above 70° C.; applying pressure during the sintering step.

6 . The process of claim 1 , the printing sol being characterized by at least one or all of the following features:
being translucent in a wavelength range from 420 to 600 nm for a path length of 10 mm; showing a transmission of at least 5% at 420 nm determined for a path length of 10 mm; pH value: from 1 to 6.

7 . The process of claim 1 , the printing sol being characterized by at least one or more or all of the following features:
the nano-sized particles being present in an amount from 20 to 70 wt.-% with respect to the weight of the sol; the average primary particle size of the nano-sized zirconia particles being in a range up to 50 nm.

8 . The process of claim 1 , the nano-sized particles being characterized by at least one or all of the following features:
being crystalline; 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 A1203 in an amount of 0 to 1 mol-%.

9 . The process of claim 1 , the printing sol comprising in addition organic dye(s).

10 . The process of claim 9 , the organic dye being characterized by at least one or all of the following features:
being present in an amount from 0.001 to 0.5 wt.-% with respect to the weight of the sol; showing a radiation absorption in the range from 200 to 500 nm; having a molecular weight in the range of 100 to 1,000 g/mol; being soluble in the solvent; being combustible without residues at a temperature below 800° C.; not containing heavy metal ions with an atomic mass above 40.

11 . The process of claim 1 , the printing sol in addition comprising inhibitor(s), preferably in an amount from 0.001 to 1 wt.-% with respect to the weight of the sol.

12 . The process of claim 1 , the radiation curable monomer(s) being characterized by at least one or all of the following features:
being represented by a formula A-B with A comprising an acidic group, a silane group, an amine, amide or alcohol group and B comprising a vinyl group; being present in the printing sol in an amount from 2 to 30 wt.-% with respect to the weight of the printing sol.

13 . The process of claim 1 , the printing sol not comprising either or all of the following components:
wax(es) in an amount of more than 0.1 wt.-%; insoluble pigment(s) in an amount of more than 0.5 wt.-%; particles having a primary particle diameter larger than 100 nm in an amount of more than 1 wt.-%;
wt.-% with respect to the weight of the sol.

14 . A ceramic article obtained by the process of claim 1 , the ceramic article being characterized by either or all 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.-%; dimension in either x, y or z direction: at least 0.25 mm.

15 . The ceramic article of claim 14 , the ceramic article having the shape of a dental or orthodontic article.

Assignees

• 3M Innovative Properties Co

Inventors

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

Classifications

• A61K6/807

  comprising magnesium oxide · CPC title

• A61K6/818

  comprising zirconium oxide · CPC title

• A61K6/822

  comprising rare earth metal oxides · CPC title

• A61K6/802

  comprising ceramics · CPC title

• B33Y80/00

  Products made by additive manufacturing · CPC title