Powder coating method for manufacturing 3D-printed components having improved mechanical properties
The invention relates to a method for producing an object from different powdered components by means of additive manufacturing, wherein a plurality of powdered components having different melting points are simultaneously placed in precise positions, and the powder coating ( 1 ) is subsequently thermally treated. The construction material is, for example, polyether ether ketone (PEEK), polyaryl ether ketone (PAEK), polyether ketone ketone (PEKK), polyether sulfone, polyimide, polyether imide, polyester, polyamides, polycarbonates, polyurethanes, polyvinyl chloride, polyoxymethylene, polyvinyl acetate, polyacrylates, polymethacrylates, polyethylene, polypropylene, polylactide, ABS (acrylonitrile butadiene styrene copolymers), PETG (glycol modified polyethylene terephthalate), polystyrene, or mixtures thereof. The supporting material is an inorganic salt of the alkali metals, an inorganic salt of the alkaline earth metals, or a mixture thereof.
1. A method of additive manufacture of a component, comprising:
a) laying at least two different pulverulent components having a difference in melting point of ≥50° C. at least once on a substrate or on an already laid powder layer as one or more powder layers, wherein a pulverulent component having the lowest melting point is laid in a powder layer in the form of the component and a pulverulent component having the highest melting point is laid in the powder layer as a negative of the form of the component;
b) subjecting individual powder layers and/or a plurality of powder layers to heat treatment at a temperature above the melting point of the pulverulent component having the lowest melting point and below the melting point of the pulverulent component having the highest melting point to form one or more heat-treated powder layers, wherein powder constituents of the pulverulent component having the lowest melting point are melted and at least partially fused;
c) cooling the one or more heat-treated powder layers from step b) down to a temperature below the melting point of the pulverulent component having the lowest melting point; and
d) removing unfused pulverulent components to obtain the component,
wherein
either: the pulverulent component having the lowest melting point comprises polyetheretherketone, polyaryletherketone, polyetherketoneketone, polyethersulfones, polyimide, polyetherimide, polyester, polyamides, polycarbonates, polyurethanes, polyvinylchloride, polyoxymethylene, polyvinylacetate, polyacrylates, polymethacrylates, polyethylene, polypropylene, polylactide, acrylonitrile-butadiene-styrene copolymers, glycol-modified polyethylene terephthalate, polystyrene, or mixtures of at least two of the aforementioned polymers, and in that
the pulverulent component having the highest melting point comprises an inorganic salt of an alkali metal, an inorganic salt of an alkaline earth metal, or a mixture of at least two of the aforementioned salts,
or: the pulverulent component having the lowest melting point comprises polychloroprene, polybutadiene, polybutadienenitrile, hydrogenated polybutadienenitrile, ethylene-vinyl acetate, fluoro rubber, styrene-butadiene block copolymers, polyvinylchloride, polyvinylacetate, polyfluoroethylene, or polyarylsulfone, and in that
the pulverulent component having the highest melting point comprises NaCl, MgSO 4 , MgCl 2 , or CaSO 4 , with the proviso that CaSO 4 is not combined with polyfluoroethylene.
2. The method as claimed in claim 1 , wherein 90% by weight of the particles of the pulverulent component having the lowest melting point have a particle diameter measured according to ISO 13320:2009-10 of ≤0.25 mm.
3. The method as claimed in claim 1 , wherein a ratio of the average particle diameter of the pulverulent component having the lowest melting point to the average particle diameter of the pulverulent component having the highest melting point, calculated from D low /D high , is ≥1 and ≤10.
4. The method as claimed in claim 1 , wherein the heat treatment in step b) is effected at a pressure difference of ≥25 kPa based on standard pressure.
5. The method as claimed in claim 1 , wherein the heat treatment in method step b) is preceded by contacting the one or more powder layers with an inert gas.
6. The method as claimed in claim 1 , wherein an average temperature in method step b) is ≥20° C. higher than an average temperature in method step a).
7. The method as claimed in claim 1 , wherein at least 3 pulverulent components are used, wherein at least 2 of the 3 pulverulent components comprise polyurethanes having a Shore hardness ascertained according to DIN EN ISO 7619-1:2012 of ≥40A to ≤90D, and a differential in the Shore hardnesses between the 3 pulverulent components is ≥2A to ≤40A.
8. The method as claimed in claim 1 , wherein at least 3 pulverulent components are used, wherein at least 2 of the 3 pulverulent components comprise polyurethanes having a Shore hardness ascertained according to DIN ISO 7619-1:2012 of ≥40A to ≤90D, and a differential in the Shore hardnesses between the pulverulent components is ≥2A to ≤40A, and at least one pulverulent component has a melting point of ≥50° C. above the melting points of the other pulverulent components.
9. The method as claimed in claim 1 , wherein the laying of the pulverulent components in method step a) via a location-selective laying method comprising powder screenprinting, powder suspension screenprinting, electrostatic roll or plate powder laying methods, powder jetting, powder dispensing, or combinations of at least two methods therefrom.
10. The method as claimed in claim 1 , wherein a low-melting powder is a reactive powder which is reacted in method step b).