Material for 3D printing and a 3D printed device

Abstract

A material for 3D printing is described. The material comprises a polymeric composition comprising a thermoplastic polymer; and from 50 to 99 wt. % ceramic particles comprising a metal, wherein at least 50% by weight of the particles have a diameter in a range from 10 to 100 μm; wherein the material has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

Claims

1. A material for 3D printing comprising: a polymeric composition comprising a thermoplastic polymer; and from 50 to 99 wt. % ceramic particles comprising a metal, wherein at least 50% by weight of the particles have a diameter in a range from 10 to 100 μm; wherein the material has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

2. The material according to claim 1, wherein the material has a dielectric strength of at least 8 kV/mm and/or a dielectric constant of at least 10.

3. The material according to claim 1 comprising at most 95 wt. % particles.

4. The material according to claim 1, wherein at least 50% by weight of the particles have a diameter in a range from 15 to 45 μm.

5. The material according to claim 1, wherein the particles comprise an oxide of the metal, wherein the metal is a transition metal.

6. The material according to claim 1, wherein the thermoplastic polymer is selected from a group consisting of poly(methyl methacrylate) (PMMA), acrylonitrile butadiene styrene (ABS), aliphatic or semi-aromatic polyamides, polylactic acid (polylactide) (PLA), polybenzimidazole (PBI), polycarbonate (PC), polyether sulfone (PES), polyetherimide, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and polybutene-1 (PB-1), polystyrene (PS), polyvinyl chloride (PVC) thermoplastic polyurethane (TPU), poly(meth)acrylate, polyphenylene sulphone (PPSU), high density polyethylene HDPE, polyetherimide (PEI), polyether ether ketone (PEK, and nylon.

7. A filament for fused filament fabrication (FFF) formed from the material according to claim 1.

8. A method of providing a material for 3D printing comprising: sintering ceramic particles comprising a metal; milling the sintered particles, wherein at least 50% by weight of the milled particles have a diameter in a range from 10 to 100 μm; mixing the milled particles in an amount of from 50 to 99 wt. % with a polymeric composition comprising a thermoplastic polymer to provide a mixture; heating the mixture thereby melting the thermoplastic; and cooling the mixture thereby providing the material; wherein the material has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

9. The method according to claim 8, comprising providing a filament of the material by extruding the mixture.

10. An electrical energy storage device formed at least in part by fused filament fabrication (FFF), wherein the at least part of the electrical energy storage device comprises the material according to claim 1.

11. A method of forming an electrical energy storage device at least in part by fused filament fabrication (FFF), the method comprising: providing a filament formed from the material according to claim 1; melting at least a part of the filament; and solidifying the melted part of the filament to form at least a part of the electrical energy storage device, wherein the formed at least part of the electrical energy storage device has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

12. The method according to claim 11, wherein melting the at least a part of the filament is carried out in an oxygen-free atmosphere, and wherein the oxygen-free atmosphere comprises nitrogen, sulfur hexafluoride (SF.sub.6), hydrogen (H.sub.2), helium (He), and/or mixtures thereof.

13. The method according to claim 11, wherein the formed at least part of the electrical energy storage device has a porosity of at most 1% by volume of the formed at least part of the electrical energy storage device and/or wherein at most 50% by volume of pores therein have a diameter of at most 1 μm.

14. An electrical energy storage device comprising the material according to claim 1.

15. A filament comprising the material according to claim 1.

16. The method according to claim 11, wherein melting the at least a part of the filament is carried out using a heated extrusion nozzle, and solidifying the melted part of the filament to form at least a part of the electrical energy storage device occurs after extrusion of the filament from the nozzle.

17. The material according to claim 1, wherein the material has a porosity of at most 1% by volume of the material and/or wherein at most 50% by volume of pores therein have a diameter of at most 1 μm.

18. A filament material for 3D printing, the material comprising: a polymeric composition comprising a thermoplastic polymer; and from 50 to 95 wt. % ceramic particles comprising a metal, wherein at least 50% by weight of the particles have a diameter in a range from 15 to 45 μm; wherein the material has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

19. The material according to claim 18, wherein the particles comprise an oxide of the metal, wherein the metal is a transition metal.

20. The material according to claim 18, wherein the material has a porosity of at most 1% by volume of the material and/or wherein at most 50% by volume of pores therein have a diameter of at most 1 μm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a better understanding of the invention, and to show how exemplary embodiments of the same may be brought into effect, reference will be made, by way of example only, to the accompanying diagrammatic Figures, in which:

(2) FIG. 1 schematically depicts an electrical energy storage device according to an exemplary embodiment;

(3) FIGS. 2A-2B schematically depict an electrical energy storage device according to an exemplary embodiment;

(4) FIG. 3 schematically depicts an electrical energy storage device according to an exemplary embodiment;

(5) FIGS. 4A-4B schematically depict an electrical energy storage device according to an exemplary embodiment;

(6) FIGS. 5A-5B schematically depict an electrical energy storage device according to an exemplary embodiment;

(7) FIG. 6 schematically depicts a jig arrangement for a conventional electrical energy storage;

(8) FIGS. 7A-7B schematically depict a conventional electrical energy storage device;

(9) FIGS. 8A-8B schematically depict parts of an electrical energy storage device according to an exemplary embodiment;

(10) FIG. 9 schematically depicts a part of an electrical energy storage device according to an exemplary embodiment;

(11) FIG. 10 schematically depicts a method according to an exemplary embodiment; and

(12) FIG. 11 schematically depicts a method according to an exemplary embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

(13) Generally, like reference signs denote like features, description of which is not repeated for brevity.

(14) FIG. 1 schematically depicts an electrical energy storage device 4 according to an exemplary embodiment.

(15) Particularly, the electrical energy storage device 4 is formed at least in part by Fused Deposition Modelling (FDM), wherein the at least part of the electrical energy storage device 4 has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

(16) In more detail, the electrical energy storage device 4 is a block capacitor 4 which contains a first electrode 1 and a second electrode 2 sandwiching a block of dielectric material 5. The first electrode 1 is connected to an electrical contact 6 and the second electrode 2 is connected to an electrical contact 7. The capacitor structure is then encapsulated (potted) in a suitable potting material 3, so as to avoid electrical breakdown of the capacitor 4.

(17) Particularly, the block of dielectric material 5 is formed by FDM of a material comprising:

(18) a polymeric composition comprising a thermoplastic polymer; and

(19) from 50 to 99 wt. % ceramic particles comprising a metal, wherein at least 50% by weight of the particles have a diameter in a range from 10 to 100 μm;

(20) wherein the material has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

(21) FIGS. 2A-2B schematically depict an electrical energy storage device 14 according to an exemplary embodiment.

(22) Particularly, the electrical energy storage device 14 is formed at least in part by Fused Deposition Modelling (FDM), wherein the at least part of the electrical energy storage device 14 has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

(23) In more detail, the electrical energy storage device 14 is a capacitor set up 14. FIG. 2A shows a side projection of a capacitor set up 14, with a first electrode 16 with protrusions 11, and a second electrode 17, with protrusions 12. The protrusions 11 and 12 have been designed to mate together such that the height of the final mated capacitor plate is only a few millimetres thicker than the thickness of one of the electrodes with its associated protrusions. In between the protrusions 11 and 12, there is a defined gap 13, into which the opposing protrusion and a dielectric material F (not shown) will fit.

(24) On the rear face 18 of the electrode 17, as shown in FIG. 2B, there is a plurality of voids 19, which extend as through holes, which are located in the electrode structure 17. The holes 19 permit the flow of a conventional curable flowable liquid dielectric, for example a resin, into the gaps 13, between the protrusions (dotted lines) 12. Without the presence of the holes 19 the dielectric would not migrate in between the mated protrusions, as the likely gap between the two sets of mated protrusions 11 and 12 will be of the order of a few millimetres.

(25) In contrast, by forming the dielectric material 15 by FDM, rather than using the conventional curable flowable liquid dielectric, the holes 19 are not required, thereby simplifying manufacture of the electrical energy storage device 14. Furthermore, problems associated with air pockets formed by incomplete flow of the conventional curable flowable liquid dielectric and/or shrinkage of the conventional curable flowable liquid dielectric upon curing and/or solidification, for example, may be avoided.

(26) The dielectric material 15 is as described with respect to the dielectric material 5.

(27) FIG. 3 schematically depicts an electrical energy storage device 24 according to an exemplary embodiment.

(28) Particularly, the electrical energy storage device 24 is formed at least in part by Fused Deposition Modelling (FDM), wherein the at least part of the electrical energy storage device 24 has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

(29) In more detail, the electrical energy storage device 24 is a capacitor 24. FIG. 3 shows a top view of one half of the capacitor 24, the electrode 26 has a series of upstanding protrusions 21, which define a generally semi-circular pattern, similar to that shown in FIG. 2A. The generally circular pattern is broken up by voids in the form of slits 27, which extend the entire height of the protrusion 21. There are also additionally further voids in the form of through holes 29. The electrode 26 will have a mating pair (not shown) similar to that shown in FIG. 2A, with similar slits and holes.

(30) When the mated pair are brought together, the holes 29 and slits 27 allow a conventional curable flowable liquid dielectric, for example a resin, to be flowed evenly throughout the mated structure.

(31) In contrast, the electrical energy storage device 24 comprises a dielectric material 25 (not shown) formed by FDM, rather than the conventional curable flowable liquid dielectric, that has a shape to conform with the mated electrodes 26. Hence, the holes 29 and the slits 27 are not required, thereby simplifying manufacture of the electrical energy storage device 24. Furthermore, problems associated with air pockets formed by incomplete flow of the conventional curable flowable liquid dielectric and/or shrinkage of the conventional curable flowable liquid dielectric upon curing and/or solidification, for example, may be avoided.

(32) The dielectric material 25 is as described with respect to the dielectric material 5.

(33) FIGS. 4A-4B schematically depict an electrical energy storage device 34 according to an exemplary embodiment.

(34) Particularly, the electrical energy storage device 34 is formed at least in part by Fused Deposition Modelling (FDM), wherein the at least part of the electrical energy storage device 34 has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

(35) In more detail, the electrical energy storage device 34 is a capacitor structure 34. FIG. 4A shows a side projection of one half of the capacitor structure 34. The electrode 37 has a plurality of parallel fins 32, arranged with a gap 33 between each fin, the gap has a dimension 39 which permits the location of the corresponding protrusions 31, which are located on a second electrode 37, and the dielectric material 35 (not shown).

(36) The outer circumference of the capacitor structure 34 has no perimeter, such that the open ends of the fins behave as slits 38, which readily permits the flow of a conventional curable flowable liquid dielectric material between the gap when the fins are mated together as shown in FIG. 4B.

(37) FIG. 4B clearly shows the mating of the fins 31 and 32 which are the protrusions on electrodes 36 and 37, respectively.

(38) In contrast, the electrical energy storage device 34 comprises the dielectric material 35 (not shown) formed by FDM, rather than the conventional curable flowable liquid dielectric, that has a shape to conform with the mated electrodes 37. Hence, the slits 38 are not required, thereby simplifying manufacture of the electrical energy storage device 34. Furthermore, problems associated with air pockets formed by incomplete flow of the conventional curable flowable liquid dielectric and/or shrinkage of the conventional curable flowable liquid dielectric upon curing and/or solidification, for example, may be avoided.

(39) The dielectric material 35 is as described with respect to the dielectric material 5.

(40) FIGS. 5A-5B schematically depict an electrical energy storage device 44 according to an exemplary embodiment.

(41) Particularly, the electrical energy storage device 44 is formed at least in part by Fused Deposition Modelling (FDM), wherein the at least part of the electrical energy storage device 24 has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

(42) In more detail, the electrical energy storage device 44 is a capacitor 44. FIG. 5a shows a cross-section of a mated structure of circular protrusions as shown in FIG. 2A. The capacitor comprises circular fins 41 on a first electrode 46 with mated with circular fins 42 on a second electrode 47, (as shown in FIG. 2A), the gap between the fins 41 and 42 has been filled with a dielectric material 45. A reservoir for excess conventional curable flowable liquid dielectric material 45a is shown at the distil ends of the drawing, the excess is there to ensure that there is sufficient conventional curable flowable liquid dielectric material to flow through the structure and to ensure all conductive areas of the electrodes 46 and 47 are encapsulated to ensure there is no potential for an electrical short.

(43) In contrast, the electrical energy storage device 44 comprises the dielectric material 45 formed by FDM, rather than the conventional curable flowable liquid dielectric, that has a shape to conform with the mated electrodes 46 and 47. Hence, the reservoir for excess conventional curable flowable liquid dielectric material 45a is not required, thereby simplifying manufacture of the electrical energy storage device 44. Furthermore, problems associated with air pockets formed by incomplete flow of the conventional curable flowable liquid dielectric and/or shrinkage of the conventional curable flowable liquid dielectric upon curing and/or solidification, for example, may be avoided.

(44) The dielectric material 45 is as described with respect to the dielectric material 5.

(45) FIG. 5B shows a model of the electrical fields generated in a capacitor similar to that in FIG. 5B. The capacitor has been optimised, the first electrode 46 and second electrode 47 have been provided with complex geometries. The central protrusion 42a has been designed to be of a greater thickness 48 than the thickness of the other fins 48a. A further modification has been made the protrusions 41, 42, by enlarging the radius of the rounded tips 49 of the protrusion. These modifications have reduced unwanted field enhancements.

(46) FIG. 6 schematically depicts a jig arrangement for a conventional electrical energy storage device, in which a conventional curable flowable liquid dielectric material is used.

(47) Particularly, FIG. 6 shows one example of a jig arrangement 54, where the outer casing 58, 59 can be removed after construction of a capacitor. The jig 54 comprises two casing halves 58, 59 which hold the first electrode 51 and second electrode 52 respectively. The two halves 58, 59 are brought into alignment by locating lugs 56 and receiving holes 57. The thickness of the jig 59 ensures that the plurality of fins 53 and 53a engage to the correct depth. The action of the two halves 58, 59 and the thickness of jig 59 ensures that the fins 53 and 53a interlocate with a uniform spacing provided therebetween.

(48) In contrast, by providing an electrical energy storage device comprising a dielectric material formed by FDM, rather than the conventional curable flowable liquid dielectric, such a jig arrangement 54 is not required since the dielectric material formed by FDM may determine the spacing between corresponding electrodes, thereby simplifying manufacture of the electrical energy storage device. Furthermore, problems associated with air pockets formed by incomplete flow of the conventional curable flowable liquid dielectric and/or shrinkage of the conventional curable flowable liquid dielectric upon curing and/or solidification, for example, may be avoided.

(49) FIGS. 7A and 7B schematically depict a jig arrangement for a conventional electrical energy storage device, in which a conventional curable flowable liquid dielectric material is used.

(50) In more detail, FIGS. 7A and 7B show a further arrangement with an integrated jig 63, which provides the correct spacings between the first electrode 61 and second electrode 62.

(51) The first and second electrode 61, 62 have the fin type arrangement as shown in FIG. 4B.

(52) The central protrusion 61a has been designed to be of a greater thickness than the thickness of the other fins 61. The radii of the bottom of the fins 69 have been enlarged to provide rounded tips of the fin protrusions. The second electrode 62 has an additional wall 64, so as to create a well so that the entire structure may be filled by a flowable dielectric. The gap 66 between the two electrodes is then filled by the conventional curable flowable liquid dielectric material to provide a final capacitor structure. To permit a more reproducible fill, fill holes 68 are located such that all of the gap 66 may be completely filled with dielectric material.

(53) After the dielectric (not shown) has been cured, the area defined by box 65, is then machined away to remove the unwanted jig 63 and excess well area defined by wall 64.

(54) In contrast, by providing an electrical energy storage device comprising a dielectric material formed by FDM, rather than the conventional curable flowable liquid dielectric, such a jig arrangement is not required since the dielectric material formed by FDM may determine the spacing between corresponding electrodes, thereby simplifying manufacture of the electrical energy storage device. For example, the dielectric material formed by FDM may have a shape to conform with the shape of the gap 66. In addition, the holes 68 are not required. Furthermore, problems associated with air pockets formed by incomplete flow of the conventional curable flowable liquid dielectric and/or shrinkage of the conventional curable flowable liquid dielectric upon curing and/or solidification, for example, may be avoided.

(55) The dielectric material formed by FDM is as described with respect to the dielectric material 5.

(56) FIGS. 8A-8B schematically depict parts 75A, 75B of an electrical energy storage device according to an exemplary embodiment. Particularly, FIGS. 8A-8B respectively show photographs of the parts 75A, 75B of the electrical energy storage device formed at least in part by Fused Deposition Modelling (FDM), wherein the at least parts 75A, 75B of the electrical energy storage device have a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

(57) In detail, the parts 75A, 75B are formed by FDM from a dielectric material as described with respect to the dielectric material 5. The part 75A is frustoconical, having a wall thickness that decreases towards the end having the larger diameter. The part 75B is frustoconical, having a wall thickness that decreases towards the end having the smaller diameter.

(58) FIG. 9 schematically depicts a part 85 of an electrical energy storage device according to an exemplary embodiment. Particularly, FIG. 9 shows a photograph of the part 85 of the electrical energy storage device formed at least in part by Fused Deposition Modelling (FDM), wherein the at least part 85 of the electrical energy storage device has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

(59) In detail, the part 85 is formed by FDM from a dielectric material as described with respect to the dielectric material 5. The part 85 is a circular pipe, having constant internal and external diameters.

(60) FIG. 10 schematically depicts a method according to an exemplary embodiment. Particularly, FIG. 10 schematically depicts a method of providing a material for 3D printing according to an exemplary embodiment.

(61) At S1001, ceramic particles comprising a metal are sintered.

(62) At S1002, the sintered particles are milled, wherein at least 50% by weight of the milled particles have a diameter in a range from 10 to 100 μm.

(63) At S1003, the milled particles are mixed in an amount of from 50 to 99 wt. % with a polymeric composition comprising a thermoplastic polymer to provide a mixture.

(64) At S1004, the mixture is heated, thereby melting the thermoplastic.

(65) At S1005, the mixture is cooled, thereby providing the material, wherein the material has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

(66) The method may include any of the steps described herein, for example as described with respect to the third aspect. The ceramic particles, the metal, the polymeric composition comprising the thermoplastic polymer and/or the material may be as described herein, for example as described with respect to the first aspect.

(67) FIG. 11 schematically depicts a method according to an exemplary embodiment. Particularly,

(68) FIG. 11 schematically depicts a method of forming an electrical energy storage device at least in part by Fused Deposition Modelling (FDM) according to an exemplary embodiment.

(69) At S1101, a filament according to the second aspect is provided.

(70) At S1102, at least a part of the filament is melted in an oxygen-free atmosphere.

(71) At S1103, the melted part of the filament is solidified to form at least a part of the electrical energy storage device, wherein the formed at least part of the electrical energy storage device has a dielectric strength of at least 5 kV/mm and/or a dielectric constant of at least 5.

(72) The method may include any of the steps described herein, for example as described with respect to the fifth aspect. The filament may be as described herein, for example as described with respect to the second aspect. The ceramic particles, the metal, the polymeric composition comprising the thermoplastic polymer and/or the material may be as described herein, for example as described with respect to the first aspect.

(73) Although a preferred embodiment has been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims and as described above.

(74) In summary, the invention provides a material for 3D printing, as set forth in the appended claims. Also provided is a filament of the material, a method of providing the material, a device formed from the material, a method of forming the device and use of the material to provide a device. In this way, by providing ceramic particles in a material comprising additionally a polymeric composition comprising a thermoplastic polymer, a dielectric strength of the material may be increased compared with the ceramic material, to the dielectric strength of at least 5 kV/mm. Furthermore, by including the ceramic particles in the material in an amount of from 50 to 99 wt. %, the material may still have relatively high dielectric constant of at least 5, such that a relatively high capacitance and/or a relatively high volumetric electrical energy storage density of the material may be provided. In addition, by providing the material for 3D printing, complex electrical energy storage devices may be formed by 3D printing therefrom. In this way, relatively complex shapes of the electrical energy storage device may be provided, as formed by the FDM. By forming the electrical energy storage device at least in part by FDM, net or near-net solid shapes may be provided that may be assembled with corresponding electrodes, simplifying electrode design and/or manufacture and/or reducing or eliminating further processing steps and/or jig arrangements.

(75) Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

(76) All of the features disclosed in this specification (including any accompanying claims and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at most some of such features and/or steps are mutually exclusive.

(77) Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

(78) The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.