Multicolour extrusion-based 3D print process
View Patent ↗A 3D extrusion print process for producing multicolored three-dimensional objects is provided. The process produces mechanically stable, multicolored 3D objects with good color definition. The process according to the invention is based on coating, upstream of the printing head, of the polymer strand used for producing the actual object, and on fixing of the coating upstream of entry of the polymer strand into the printing head. Downstream of the extrusion process in the printing head, the coating remains predominantly at the surface of the extruded strand.
1. A 3D extrusion printer, comprising:
a first printing head comprising a nozzle which receives a coated solid build material filament, melts the coated solid build material filament, thereafter applies the melted coated solid build material as print to a print bed;
a filament supply stream in communication with the first printing head which supplies a fixed coated solid build material filament to the first printing head;
a coating unit upstream to the first printing head on the filament supply stream which applies a coating to a solid build material filament;
a coating fixing region located between the coating unit and the first printing head;
a plurality of feed containers equipped with metering devices to supply a coating composition comprising at least one of an additive and an ink to the coating unit; and
a mixing unit between and in communication with the plurality of feed containers wherein the coating composition is mixed prior to being supplied to the coating unit; and
wherein the coating material applied to the filament in the coating unit is completely or incompletely fixed in the fixing region before entering the first printing head.
2. The 3D extrusion printer according to claim 1 , wherein the first printing head further comprises a static mixer in a lower region of the nozzle.
3. The 3D extrusion printer according to claim 1 , further comprising:
a guide system or a brake upstream of the coating unit; and
a conveying unit between the fixing region and the first printing head; such that the solid build material filament is tensioned in the coating unit by the guide system or brake and the conveying unit.
4. The 3D extrusion printer according to claim 1 further comprising:
a second printing head configured for applying a support material as print; and
optionally, a third printing head constructed equivalently to the second printing head which is configured for applying a filament stream for a second build material.
5. The 3D extrusion printer according to claim 4 , comprising the third printing head, wherein
the second printing head is configured for applying the support material that upstream of the coating process the filament is not colored and is non-transparent, and the third printing head is configured for applying a build material that upstream of the coating process is not colored and is transparent.
6. The 3D extrusion printer according to claim 4 wherein the second and third printing heads each respectively have dedicated mixing devices, which are in communication with common ink-feed containers of the plurality of feed containers.
7. The 3D extrusion printer according to claim 4 , comprising the third printing head, wherein
the first and third printing heads are each independently configured to apply materials comprising: a thermoplastically processable material, and
the second printing head is configured to apply material comprising: a polymethacrylate or a polycarbonate.
8. The 3D extrusion printer according to claim 7 , wherein the thermoplastically processable material of the first and third printing heads comprises a polymer selected from the group consisting of an acrylonitrile-butadiene-styrene terpolymer (ABS), a polycarbonate (PC), a poly(meth)acrylate, a polyphenylene sulfone (PPSU), a high density polyethylene (HDPE), a polyetherimide (PEI), a polyether ether ketone (PEEK) and a polylactic acid (PLA).
9. The 3D extrusion printer according to claim 4 , wherein the support material of the second printing head comprises an acid-soluble, base-soluble or water-soluble polymer.
10. The 3D extrusion printer according to claim 1 , further comprising a computer wherein a color shade of the print is input into a CAD program, and that a file is provided to the computer which comprises, in addition to coordinates, color information for the manufacturing process and for the regulation of the formulation of materials and of inks such that respective color shade is established through regulation of the metering devices and controlled metering of primary colors and black inks from the plurality of feed containers into the coating unit.
11. The 3D extrusion printer according to claim 1 , wherein one of the plurality of feed containers is configured for applying materials comprising: a colorless coating composition which comprises one selected from the group consisting of an activatable additive, an adhesion promoter and an adhesive.
12. The 3D extrusion printer according to claim 1 , wherein the fixing region comprises a fixing unit or is a length measuring at least 1 cm.
13. The 3D extrusion printer according to claim 1 , further comprising sensors arranged upstream of the first printing head, wherein the sensors determine the diameter of the coated solid build filament and the flow of materials to the coating unit is optimized with information for color monitoring and print control.