Three-dimensional object and manufacturing method thereof

Abstract

The present invention concerns a method for the manufacture of a three-dimensional object, comprising (a) providing a three-dimensional model of the object, which divides the object in voxels; (b) applying a first layer of a radiation-curable slurry onto a target surface, wherein the slurry contains a polymerizable resin and a photoinitiator; (c) polymerizing the resin by illuminating the voxels of the first layer in accordance with the model with radiation at a temperature above room temperature and above the glass transition temperature of the polymerized resin, to cause polymerization of the resin to form a cross-linked polymeric matrix; (d) applying a subsequent layer of the slurry on top of the first layer; (e) polymerizing the resin by scanning the voxels of the subsequent layer in accordance with the model with radiation at a temperature above room temperature and above the glass transition temperature of the polymerized resin, to cause polymerization of the resin to form a cross-linked polymeric matrix; (f) repeating steps (d) and (e), wherein each time a subsequent layer is applied onto the previous layer, to produce a green body; and optionally (g) debinding and (h) sintering of the three-dimensional object. The invention further concerns the three-dimensional object obtained thereby and an additive manufacturing system suitable for performing the method according to the invention.

Claims

1. A method for the manufacture of a three-dimensional object, comprising: (a) providing a three-dimensional model of the object, which divides the object in voxels; (b) applying a first layer of a radiation-curable slurry onto a target surface, wherein the slurry contains a polymerizable resin and a photoinitiator; (c) polymerizing the resin by illuminating the voxels of the first layer in accordance with the model with radiation at a temperature above room temperature and above the glass transition temperature of the polymerized resin, to cause polymerization of the resin to form a cross-linked polymeric matrix; (d) applying a subsequent layer of the slurry on top of the first layer; (e) polymerizing the resin by illuminating the voxels of the subsequent layer in accordance with the model with radiation at a temperature above room temperature and above the glass transition temperature of the polymerized resin, to cause polymerization of the resin to form a cross-linked polymeric matrix; (f) repeating steps (d) and (e), wherein each time a subsequent layer is applied onto the previous layer, to produce a green body; and optionally: (g) removing the cross-linked polymeric matrix from the green body obtained in step (f) to obtain a brown body; and (h) sintering the brown body obtained in step (h) to obtain a white body, wherein the green body or the white body is the three-dimensional object.

2. The method according to claim 1, wherein the temperature applied in step (c) and each occurrence of step (e) is in the range of 40-100° C.

3. The method according to claim 1, wherein the resin comprises monomers and/or oligomers that are polymerizable via radiation, preferably wherein the monomers are selected from urethanes, vinyl ether acrylates, allyl ether acrylates, maleimide acrylates, thiol acrylates, epoxide acrylates, oxetane acrylates and combinations thereof.

4. The method according to claim 1, wherein the temperature during step (b) and each occurrence of step (d) is the same as in step (c) and each occurrence of step (e).

5. The method according to claim 1, wherein the slurry further comprises one or more of metal, metal precursor, metal oxide or ceramic particles, preferably zirconium oxide particles.

6. The method according to claim 1, wherein the slurry comprises: (i) 2-45 wt % of a polymerizable resin; (ii) 0.001-10 wt % of one or more polymerization photoinitiators; (iii) 55-98 wt % of the particles.

7. Method according to claim 1, wherein the thickness of the first and subsequent layers of slurry is between 5 and 300 μm, preferably between 6 and 200 μm, most preferably between 9 and 100 μm.

8. Method according to claim 1, wherein the radiation is chosen from the group consisting of actinic types of radiation, preferably UV-radiation.

9. Method according to claim 1, wherein the method is a stereolithographic (SLA) method wherein illuminating of the voxels of the slurry layers in steps (c) and (e) in accordance with the model is performed voxel-by-voxel; or a Dynamic Light Processing (DLP) method wherein illuminating of the voxels of the slurry layer in steps (c) and (e) is performed by simultaneously exposing all voxels in the layer to radiation.

10. Three-dimensional object, obtainable by the process according to claim 1.

11. The three-dimensional object according to claim 10, which is made from plastic, metal, metal oxide and/or ceramics.

12. An additive manufacturing system comprising a 3D-printer including: (i) a substrate having a surface for depositing a layer of radiation-curable slurry, (ii) a slurry depositor for containing and configured for depositing the slurry onto the substrate, (ii) a stage configured to hold the three-dimensional object that is being manufactured, (iv) a radiation source arranged to illuminate the layer of slurry deposited onto the surface, (v) a positioning system which is configured to align the radiation source with respect to the slurry that is to be cured in accordance with a 3D model, and a heating means for heating the slurry prior to being deposited onto the surface.

13. The additive manufacturing system according to claim 12, wherein the heating means are implemented into the slurry depositor, preferably wherein the heating means are capable of heating the slurry to a temperature above room temperature and above the glass transition temperature of the polymerized resin contained in the slurry, more preferably to a temperature of range of 40-100° C., most preferably 60-70° C.

14. The additive manufacturing system according to claim 13, wherein the heating means are capable of heating the slurry to a temperature of range of 40-100° C.

15. The additive manufacturing system according to claim 14, wherein the heating means are capable of heating the slurry to a temperature of range of 60-70° C.

16. The method according to claim 2, wherein the temperature applied in step (c) and each occurrence of step (e) is in the range of 60-70° C.

Description

DESCRIPTION OF THE FIGURES

[0053] FIGS. 1 and 2 depict SEM images of the three-dimensional objects obtained in example 1. The images of the conventional object (slurry at room temperature) is depicted in FIG. 1 and the images of the object according to the invention (slurry at 60° C.) are depicted in FIG. 2. Clearly visible in the conventional object are the boundaries between the separate layers, reflected by horizontal lines of remain porosity (indicated with arrows). These boundaries are not visible for the object according to the present invention. Moreover, the conventional object contains large cavities, which are not visible for the object according to the invention.

EXAMPLE

[0054] A radiation-curable slurry for additive manufacturing was made of 28 wt % of the polymerizable resin A (T.sub.g=34° C.), comprising neopentyl glycol propoxylate (2 PO) diacrylate, 0.5 wt % of photoinitiator bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (Irgacure ir819), 71.5 wt % of zirconium oxide (ZrO.sub.2) particles. A slurry was made using a high speed mixer and then heated to a temperature of 60° C. The printing was performed on an Admaflex printer at the same temperature, using radiation with a wavelength between 390 and 420 nm with a curing time of 2 s and a layer thickness of 20 μm. A control experiment was performed wherein the slurry was at room temperature (about 20° C.), and printing was performed at that same temperature. The bodies of both experiments were debinded and converted in air at a top temperature of 1000° C. Sintering occurred at a temperature of 1500° C. After sintering, a zirconium oxide body was obtained.

[0055] The resulting bodies were investigated by the naked eye and using scanning electron microscopy (SEM), see FIGS. 1 and 2. Naked eye inspection showed that the product according to the present invention had a smooth surface, while the conventional object displayed delamination cracks and moon-shaped fissures at the surface. The SEM images lead to a similar conclusion, wherein the conventional object shows delamination in the form of horizontal lines of remaining porosity at the boundary between the layers (indicated with arrows in FIG. 1), which is not present for the object according to the invention. Furthermore, the conventional object contains large cavities, which are not visible for the object according to the invention. Clearly, the inventive object is more homogeneous and suffers from reduced delamination issues, when compared to the conventional object. In the inventive object, the separate layers are no longer visible, indicative of an improved adhesion between the layers and an increased density of the object.