Method and device for producing three-dimensional objects using laser technology and for applying an absorber using an ink jet method
View Patent ↗The present invention relates to a process for the bonding of material for the production of three-dimensional objects by selective heating via a laser of wavelength from 100 to 3000 nm. The beam spot may be a focused or unfocused beam spot, or may indeed be spread, as is the case with the diode laser, where the bars may have a stacked arrangement. The selectivity of the melting process is achieved via the application of an absorber to certain subregions of a layer composed of a pulverulent substrate, and then heating of the absorber by laser radiation of wavelength from 100 to 3000 nm. The heated absorber transfers the energy present therein to its surrounding pulverulent substrate, which is melted thereby and, after cooling, has firm cohesive bonding.
1. A process for producing a three-dimensional object, the process comprising
a) providing a layer of a pulverulent substrate comprises a polymer, wherein the pulverant substrate is a powder material which is not coated, wherein the polymer is a homo- or copolymer selected from the group consisting of polyester, polyvinyl chloride, polyacetal, polypropylene, polyethylene, polystyrene, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polysulfone, polyarylene ether, polyurethane, thermoplastic elastomers, polylactides, polyoxyalkylenes, poly(Nmethylmethacrylimides) (PMMI), polymethyl methacrylate (PMMA), ionomer, polyamide, copolyester, copolyamides, silicone polymers, terpolymers, acrylonitrilebutadiene-styrene copolymers (ABS), and a mixture thereof,
b) controlling the temperature of a manufacturing chamber by supplying heat to said layer to bring said layer to an elevated temperature or to maintain said layer at an elevated temperature below the melting or sintering temperature of the polymer in said pulverulent substrate,
c) selectively applying an absorber in a suspension or a liquid absorber via an inkjet process to at least one region of the layer to be sintered,
e) selectively melting the at least one region of the layer of the pulverulent substrate by applying electromagnetic energy via a laser of a wavelength from 100 to 3000 nm,
f) cooling molten and non-molten regions obtained in e) to a temperature which allows formed moldings to be removed intact, and
g) removing the moldings intact, thereby obtaining the three-dimensional object,
wherein the selectively applying an absorber to the at least one region c) includes raising the temperature of the at least one region by preheating the absorber to a temperature higher than the temperature of the at least one region and applying the preheated absorber to the at least one region.
2. The process as claimed in claim 1 , wherein e) is first carried out once, and then a) to c) are carried out once, and then b) is carried out and a) is carried out again once, and then the other steps are carried out in the sequence c), a), b), and e).
3. The process as claimed in claim 1 , wherein the pulverulent substrate has a median grain size of from 10 to 150 μm.
4. The process as claimed in claim 1 , wherein said laser has a wavelength from 800 to 1070 nm.
5. The process as claimed in claim 1 , wherein said laser has a wavelength from 1900 to 2100 nm.
6. The process as claimed in claim 1 , wherein said laser is an Nd:YAG laser.
7. The process as claimed in claim 1 , wherein said laser is a diode laser.
8. The process as claimed in claim 1 , wherein said laser is a laser with an unfocused, linear or spread beam.
9. The process as claimed in claim 1 , wherein the absorber comprises at least one colorant.
10. The process as claimed in claim 9 , wherein the absorber comprises at least one pigment.
11. The process as claimed in claim 9 , wherein the absorber comprises at least one dye.
12. The process as claimed in claim 1 , wherein the absorber comprises at least one component selected from the group consisting of carbon black, CHP, animal charcoal, graphite, carbon fibers, chalk, and at least one interference pigment.
13. The process as claimed in claim 1 , wherein the absorber comprises at least one flame retardant based on phosphorus or melamine cyanurate.
14. The process as claimed in claim 9 , wherein the absorber also comprises distilled water, at least one alcohol, or at least one other solvent.
15. The process as claimed in claim 9 , wherein the absorber also comprises at least one component selected from the group consisting of a surfactant, a wetting agent, a biocide, and a moisture retainer.
16. The process as claimed in claim 1 , wherein said pulverulent substrate further comprises from 0.05 to 5% by weight of a powder-flow aid.
17. The process as claimed in claim 1 , wherein said pulverulent substrate further comprises at least one inorganic filler.
18. The process as claimed in claim 1 , wherein the filler comprises glass beads.
19. The process as claimed in claim 1 , wherein said pulverulent substrate further comprises at least one inorganic or organic pigment.
20. The process as claimed in claim 1 , wherein said laser is directed to the entire powder surface.