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EP-4570775-B1 - POLYMER BINDER, CERAMIC POWDER AND POLYMER BINDER FORMULATION FOR MAKING CERAMIC PARTS BY 3D PRINTING PROCESS, METHOD OF MAKING THIS FORMULATION AND METHOD OF OBTAINING A CERAMIC OBJECT

EP4570775B1EP 4570775 B1EP4570775 B1EP 4570775B1EP-4570775-B1

Inventors

  • Auzene, Delphine
  • BOUDIFA, Mohamed
  • ABID, Marwa
  • Lacrampe, Marie France
  • Ordynski, Luc
  • Charlon, Sébastien

Dates

Publication Date
20260513
Application Date
20241107

Claims (10)

  1. Polymeric binder for three-dimensional printing by extrusion of a composite element based on a ceramic compound and said polymeric binder, characterized in that said binder consists of: - PEG (polyethylene glycol) 4,000 g/mol in a proportion of between 25 and 50% (w/w); - PEG (polyethylene glycol) 10,000 g/mol in a proportion of between 0 and 25% (w/w); - a biosourced structural polymer chosen from PBSA (poly(butylene succinate co-adipate) and PBS (poly(butylene succinate)), said structural polymer being in a proportion of between 30 and 50% (w/w).
  2. Polymeric binder for three-dimensional printing according to claim 1, characterized in that it consists of: - PEG (polyethylene glycol) 4,000 g/mol in a proportion of between 25 and 30% (w/w); - PEG (polyethylene glycol) 10,000 g/mol in a proportion of between 20 and 25% (w/w); - a biosourced structural polymer chosen from PBSA and PBS in a proportion equal to 50% (w/w).
  3. Polymeric binder for three-dimensional printing according to claim 1 or claim 2, characterized in that it consists of: - PEG (polyethylene glycol) 4,000 g/mol in a proportion equal to 25% (w/w); - PEG (polyethylene glycol) 10,000 g/mol in a proportion equal to 25% (w/w); - a biosourced structural polymer chosen from PBSA and PBS in a proportion equal to 50% (w/w).
  4. Polymeric binder for three-dimensional printing according to any of claims 1 to 3, characterized in that said structural polymer is PBSA.
  5. Composite formulation, for three-dimensional printing of a composite element by extrusion, characterized in that it comprises at least one ceramic compound, stearic acid and a polymeric binder according to any of claims 1 to 4, said formulation comprising: - powder of a ceramic compound chosen from zirconia (ZrO 2 ), yttriated zirconia (YSZ), aluminum oxide (Al 2 O 3 ), hydroxyapatite (HAP Ca 5 (PO 4 ) 3 (OH)), tricalcium phosphate (TCP) in a proportion of between 74 and 85% (w/w); - said polymeric binder consisting of PEG 4000, PEG 10000 and a biosourced structural polymer chosen from PBSA and PBS, in a proportion of between 14 and 25% (w/w); - stearic acid powder in a proportion of between 0.2 and 1% (w/w).
  6. Composite formulation, for three-dimensional printing of a composite element by extrusion, according to claim 5, characterized in that it consists of: - zirconia (ZrO 2 ) or yttriated zirconia (YSZ) powder in a proportion approximately equal to or equal to 80% (w/w); - polymeric binder, consisting of 25% PEG 4000, 25% PEG 10000 and 50% PBSA or PBS, in a proportion approximately equal to or equal to 19.6% (w/w); - stearic acid powder in a proportion approximately equal to or equal to 0.4% (w/w).
  7. Method for preparing a composite formulation according to either of claims 5 or 6, and for obtaining composite granules from this formulation, said method being characterized in that it comprises, at least, the following steps: - dissolving stearic acid in a volume V1 of diethyl ether with stirring to obtain a solution of dissolved stearic acid of a volume V1'; - adding ceramic powder and a volume V2 of diethyl ether to said stearic acid solution, with stirring, so that the total volume of liquid, equal to V1'+V2, is greater than the volume of powder; - evaporating ether at room temperature in a fume hood to obtain stearic acid-coated ceramic powder particles; - mixing coated ceramic powder particles and polymeric binder together dry in a mixer and then melted together in a twin-screw extruder at a temperature of the order of, or equal to, 110°C, and obtaining the composite formulation; - extruding filaments from said composite formulation and grinding said filaments to obtain composite granules.
  8. Composite granules based on the composite formulation according to claim 5 or claim 6, obtainable according to the method of the preceding claim and comprising: - powder of a ceramic compound chosen from zirconia (ZrO 2 ), yttriated zirconia (YSZ), aluminum oxide (Al 2 O 3 ), hydroxyapatite (HAP Ca 5 (PO 4 ) 3 (OH)), tricalcium phosphate (TCP) in a proportion of between 74 and 85% (w/w); - the polymeric binder consisting of PEG 4000, PEG 10000 and PBSA or PBS in a proportion of between 14 and 25% (w/w); - stearic acid powder in a proportion of between 0.2 and 1% (w/w).
  9. Composite granules according to claim 8, characterized in that they have the following composition: - zirconia (ZrO 2 ) or yttriated zirconia (YSZ) powder in a proportion approximately equal to or equal to 80% (w/w); - polymeric binder, consisting of 25% PEG 4000, 25% PEG 10000 and 50% PBSA or PBS, in a proportion approximately equal to or equal to 19.6% (w/w); - stearic acid powder in a proportion approximately equal to or equal to 0.4% (w/w).
  10. Method for producing a ceramic part from composite granules according to claim 8 or claim 9, characterized in that it comprises the following steps: - three-dimensional printing of a composite part from composite granules according to claim 8 or claim 9; - applying thermal debinding to the composite part obtained in the previous step, the thermal debinding being carried out in temperature stages according to the following program: ∘ from an initial temperature of 25°C, increasing the temperature to which said composite part is subjected up to a first temperature stage of 140°C at a heating rate of 2°C/min; ∘ from this first temperature stage, increasing the temperature up to a second temperature stage of 170°C at a heating rate of 0.1°C/min; o from this second temperature stage, increasing the temperature up to a third temperature stage of 200°C at a heating rate of 1°C/min; ∘ from this third temperature stage, increasing the temperature up to a final temperature of 380°C at a heating rate of 0.4°C/min; - sintering at a temperature of between 1450 and 1500°C to consolidate and obtain the final ceramic part.

Description

The present invention relates to the field of manufacturing parts in technical ceramics, i.e. in non-metallic mineral materials. In particular, the object of the present invention falls within the field of manufacturing ceramic parts by three-dimensional (3D) printing, by extrusion, also known as "CIM-like" for "Ceramic Injection Moulding like", or "Material Extrusion" according to the definition of the ASTM ISO 17296-2 standard. More particularly, the present invention relates to a new formulation or composition comprising, in particular, as a ceramic material, zirconia, or zirconium dioxide ZrO2 , preferably stabilized with yttrium oxide (also called yttria-stabilized zirconia or YSZ for Yttria-Stabilized Zirconia), and a polymeric binder consisting of at least partially bio-based polymers, namely polyethylene glycol, or PEG, on the one hand, and poly(butylene succinate-co-adipate), or PBSA, or PBS (poly(butylene succinate)), on the other hand. This formulation is used more specifically in the form of granules that can be subsequently extruded for the manufacture of various ceramic parts by three-dimensional (3D) printing. The final ceramic parts, manufactured from the formulation of the invention, by 3D printing can in particular have applications in various fields such as the medical or health industry, or even in the chemical industry. Thus, for example, it is conceivable, by means of the formulation according to the present invention, to manufacture parts such as filters for applications in chemistry, bone substitutes or scaffold structures in the medical field. However, the applications mentioned above should in no way be considered as being exhaustive. In the state of the art, we already know of compositions for three-dimensional printing of ceramic parts, as well as manufacturing processes for such parts. Thus, traditionally, 3D printing of ceramic parts is carried out using granules composed of a plastic-ceramic polymer mixture, constituting the raw material, or "feedstock", and whose composition is adapted to 3D printing. This is done using a machine, consisting of a 3D printer, equipped with a means of extruding granules, for additive manufacturing of a solid object, layer by layer, based on a digital model. After the extrusion stage, and in order to obtain a fully ceramic part, a debinding stage is carried out. The objective of this stage is the complete removal of the plastic polymer binder, thus facilitating the subsequent densification stage. The part obtained after debinding is brittle and porous, with no dimensional change due to the loss of the binder. Finally, high-temperature solid-phase sintering is carried out to densify and consolidate the ceramic part. The debinding stage can be carried out in different ways, and is particularly delicate as it can cause damage to the structure of the part finally obtained. In particular, incomplete or poorly controlled removal of the polymer binder is likely to result in defects such as cracks, or chemical contamination of the final part by the presence of carbon residues from the binder that have not been properly removed. Effective and optimal debinding should prevent deformation, crumbling, swelling, or even breakage of the final ceramic part obtained by 3D printing. Thus, the main debinding techniques that can be implemented in the manufacture of ceramic parts are: thermal unbinding, by applying a controlled temperature; a chemical or catalytic debinding, by bringing the part, depending on its printing, into contact with a solvent. The main drawback of implementing thermal unbinding is that it is particularly long and energy-intensive. As for chemical debinding, it also requires contact between the part and the solvent for a relatively long time, and it is generally not sufficient for satisfactory and complete removal of the polymer binder. Therefore, chemical unbinding must almost always be followed by thermal unbinding, the major drawback of which has been mentioned above. Furthermore, the implementation of chemical unbinding is harmful to the environment and the safety of people, due to the use of chemical solvents which may, for example, produce toxic fumes. This is particularly the case with the American application published under number US 2018/162048 , in which compositions and processes with powder/binder systems are described, in which a primary binder is associated with a secondary binder, said primary binder comprising a high molecular weight polymer that can be chemically decomposed by exposure to a solvent, while the secondary binder is insoluble in that solvent. The solvent in question may consist of an aliphatic hydrocarbon, ethyl acetate, acetone, methyl ethyl ketone, trans-dichloroethylene, benzene, or toluene. It may also include water, 1,4-dioxane, dimethylformamide, or cyclohexanone. The compositions currently known and used as polymer binders in the manufacture of ceramic parts by 3D printing thus have the disadvantage of r