The invention claimed is:
1. A filamentary structure manufactured during 3D printing by liquid deposition modelling, the filamentary structure comprising a continuous strand comprising a matrix material and filler particles, wherein the filler particles comprise hexagonal boron nitride particles comprising hexagonal boron nitride platelets, and wherein the ratio of the width of the continuous strand to the height of the continuous strand is either more than 2 or less than 1.
2. The filamentary structure of claim 1 , wherein the boron nitride platelets have a mean aspect ratio of more than 7.
3. The filamentary structure of claim 1 , wherein the mean particle size (d 50 ) of the boron nitride platelets is from 5 to 100 μm.
4. The filamentary structure of claim 1 , wherein the matrix material is a polymer resin or a sol-gel system, and wherein the polymer resin is selected from the group consisting of acrylic resins, epoxy resins, polyurethane resins, silicone resins and mixtures thereof, and wherein the sol-gel system is selected from the group consisting of silica based sol-gel systems, alumina based sol-gel systems and titania based sol-gel systems.
5. The filamentary structure of claim 1 , wherein the continuous strand comprises portions being oriented parallelly to one another.
6. A 3D printed component part comprising at least one portion formed from the filamentary structure of claim 1 .
7. The component part of claim 6 , wherein the at least one portion of the component part formed from the filamentary structure has a texture index of at least 8, and wherein the ratio of the width of the continuous strand to the height of the continuous strand in the filamentary structure is more than 2.
8. The component part of claim 6 , wherein the at least one portion of the component part formed from the filamentary structure has a texture index of less than 1, and wherein the ratio of the width of the continuous strand to the height of the continuous strand in the filamentary structure is less than 1.
9. The component part according to claim 6 , wherein the at least one portion of the component part formed from the filamentary structure has a relative density of at least 60% of the theoretical density of the filamentary structure.
10. A 3D printing method for making the 3D printed component part of claim 6 , the method comprising
providing an ink composition, the ink composition comprising a matrix material and filler particles, wherein the filler particles comprise hexagonal boron nitride particles comprising hexagonal boron nitride platelets;
extruding a continuous strand from a nozzle and depositing the continuous strand on a substrate in a predetermined pattern layer by layer to form a filamentary structure, wherein the continuous strand comprises the ink composition; and
hardening the filamentary structure to form a 3D printed component part comprising a hardened matrix material and the hexagonal boron nitride particles comprising hexagonal boron nitride platelets dispersed therein, the hexagonal boron nitride platelets having a predetermined orientation in the hardened matrix material; wherein
(i) the ratio of the width of the continuous strand to the height of the continuous strand is more than 2, and wherein the hexagonal boron nitride platelets have a basal plane, and wherein the basal plane of the hexagonal boron nitride platelets in the hardened matrix material is oriented parallelly to the substrate, or
(ii) the ratio of the width of the continuous strand to the height of the continuous strand is less than 1, and wherein the hexagonal boron nitride platelets have a basal plane, and wherein the basal plane of the hexagonal boron nitride platelets in the hardened matrix material is oriented perpendicularly to the substrate.
11. The method of claim 10 , wherein the ratio of the width of the continuous strand to the height of the continuous strand is more than 2, and wherein the hexagonal boron nitride platelets have a basal plane, and wherein the basal plane of the hexagonal boron nitride platelets is oriented parallelly to the substrate.
12. The method of claim 10 , and wherein the ratio of the width of the continuous strand to the height of the continuous strand is less than 1, and wherein the hexagonal boron nitride platelets have a basal plane, and wherein the basal plane of the hexagonal boron nitride platelets is oriented perpendicularly to the substrate.
13. The method of claim 10 , wherein at least one part of the continuous strand is deposited in portions being oriented parallelly to one another.