Polymer powder with low dusting tendency for the additive manufacturing of three-dimensional objects

Abstract

The invention relates to a polymer powder for use as a construction material for the additive manufacturing of a three-dimensional object by selectively solidifying a construction material on the cross-sectional areas of the three-dimensional object in the corresponding layers, wherein the polymer powder has a proportion of substantially cylindrical particles of at least 40 wt.%, based on the total weight of the particles, the particles contain an absorber which absorbs light in the wavelength range from 400 nm to 3000 nm and / or in the range from 4800 to 8300 nm, and wherein the powder has a dust index of 15 or less and / or a dust area of 50 or less. Using corresponding polymer powders makes it possible to achieve a significant improvement in the process stability during the processing of the powders and improved properties of a three-dimensional object produced from the powder. The invention also relates to a method for producing three-dimensional objects, in which method said polymer powders are used, and to production systems for such three-dimensional objects, which production systems contain such polymer powders as construction material.

Description

[0001] August 20, 2025

[0002] EOS GmbH Electro Optical Systems M / EOSG-033-PC PF / CBE / cbe

[0003] Polymer powder for the additive manufacturing of three-dimensional objects with low dusting tendency

[0004] Description

[0005] The invention relates to a polymeric powder for use as a building material for the additive manufacturing of a three-dimensional object by selective solidification of a building material at the cross-sectional area of ​​the three-dimensional object in the corresponding layers, wherein the polymeric powder has a proportion of substantially cylindrical particles of at least 40 wt.%, based on the total weight of the particles, the particles contain an absorber that absorbs light in the wavelength range from 400 nm to 3000 nm and / or in the range from 4800 to 8300 nm, and wherein the powder has a dust index of 15 or less and / or a dust area of ​​50 or less. The present invention further relates to methods for producing three-dimensional objects in which these polymeric powders are used, as well as to manufacturing systems for such three-dimensional objects in which such polymeric powders are provided as a building material.

[0006] State of the art

[0007] Additive manufacturing encompasses various processes in which solid three-dimensional (3D) objects are created layer by layer based on a computer model. Powder-based additive manufacturing processes use powders as build materials, which are applied layer by layer to a substrate during processing. Subsequently, those parts of the layer that correspond to the objects being built are solidified. This solidification can be achieved, for example, by selective irradiation with electromagnetic radiation or by depositing a liquid ("ink") that is then activated by surface exposure. M / EOSG-033-PC

[0008] 2

[0009] An example of a powder-based additive manufacturing process is laser sintering. In laser sintering, an object is built layer by layer in a thermally controlled process chamber, which is maintained at a temperature just below the melting point of the polymer system used. After a layer of polymer particles has been applied, a laser beam is passed over the surface of the powder layer and switched on and off to selectively sinter or fuse the polymer powder particles into a shape defined by a computer. Taking into account the reduction in thickness resulting from the densification associated with the melting of the particle layers, the object is built from a 3D CAD image that has been decomposed into profile slices.

[0010] In laser sintering, powder is typically applied in thin layers, approximately 0.01 to 0.30 mm thick, to a build platform housed within a casing. After a layer has been processed, the build platform is lowered, and a new layer of powder is applied over the completed layer. Each newly applied layer is then melted and solidified according to the defined shape to ultimately form the desired three-dimensional object.

[0011] Fig. 1 shows an example of a laser sintering device commonly used with a CO₂ laser, comprising a laser beam and a deflection mirror, which enables the layer-by-layer fabrication of a three-dimensional object. As can be seen in Fig. 1, the device has a container 1. This container is open at the top and bounded at the bottom by a support 4 for carrying the object 3 to be formed. The upper edge 2 of the container (or its side walls) defines a working plane 6. The object is located on the top surface of the support 4 and is formed from a plurality of layers of a powdered build-up material, solidifiable by electromagnetic radiation, extending parallel to the top surface of the support 4. The support is movable in the vertical direction, i.e., parallel to the side wall of the container 1, via a height adjustment device.This allows the position of the support 4 relative to the working plane 6 to be adjusted. M / EOSG-033-PC.

[0012] 3

[0013] Above the container 1 or the working plane 6, an application device 10 is provided for applying the powder material 11 to be solidified onto the carrier surface 5 or a previously solidified layer. Furthermore, an irradiation device in the form of a laser 7 is arranged above the working plane 6, emitting a directed beam of light 8. This beam is deflected by a deflection device 9, for example, a rotating mirror, as a deflected beam 8' towards the working plane 6. This arrangement is common for a laser sintering system with a CO2 laser. A control unit 40 enables the control of the carrier 4, the application device 10, and the deflection device 9. The elements 1 to 6, 10, and 11 are arranged within the machine frame 100.

[0014] When processing conventional polymer powders using laser sintering, a heating system is also present to heat the polymer powder in the build chamber where the three-dimensional object is produced. Typically, the powder is heated to a temperature close to, but still below, its melting point or, in the case of amorphous polymers, its softening point, in order to minimize the amount of energy required to melt the material. Typical heating systems are radiant heaters that emit radiation in the infrared and near-infrared ranges. However, such heating systems must be precisely controlled to prevent the unintentional melting of particles or particle regions by the heating system.This problem arises particularly in the processing of polymer powders containing additives to increase the absorption of irradiated energy, since such polymer powders are relatively sensitive to the irradiated energy.

[0015] In the production of the three-dimensional object 3, the powder material 11 is applied layer by layer to the support 4 or a previously solidified layer and solidified with the laser beam 8' at the points of each powder layer corresponding to the object. After each selective solidification of a layer, the support is lowered by the thickness of the next powder layer to be applied.

[0016] In selective beam sintering, the powder is deposited and then scanned with a directed energy beam. The energy beam is usually a laser, see M / EOSG-033-PC

[0017] 4. Electron beams can also be used. In selective inhibition sintering, the powder is first applied, and then a sintering inhibitor is selectively applied to the powder before the entire layer is irradiated with electromagnetic radiation. In high-speed sintering, a layer of powder is applied, and then a radiation-absorbing liquid is selectively applied before the layer is irradiated with electromagnetic radiation.

[0018] Furthermore, processing methods are known in which binder is applied to selected areas of the powder layer and sintering only takes place in a final step, or in which selected areas of a layer are irradiated with electromagnetic radiation using a mask.

[0019] In powder-based processes, the required polymer powders are currently mostly produced by precipitation of the polymers from a solution or by milling pellets or coarse powders. However, these processes are associated with the disadvantage of relatively high costs for plant technology and solvents or the milling process and only allow the incorporation of additives into the particles to a limited extent.

[0020] A challenge in the production of three-dimensional objects where powders are melted using electromagnetic radiation is to apply the building material as uniformly and evenly as possible in powder layers. This application process is subject to a certain degree of stress depending on the application speed, with particular difficulty in achieving a flat, dense powder layer without defects ("gaps") at high application speeds. For this to be successful, the powders being applied must exhibit both a highly uniform particle size distribution and a highly flat particle shape to prevent the particles from interlocking during application. Consequently, there is a need for polymer particle powders that can be applied at high application speeds while producing highly flat and dense polymer particle layers. M / EOSG-033-PC

[0021] 5

[0022] Another problem when applying polymer particle powders to a surface is the dusting behavior of the powder mixture, with particles in the powder mixture that are significantly smaller than the majority of the particles causing particular problems. Here, too, high coating speeds, for example 600 mm / s, or fluidization of the polymer powder, as known from the prior art, lead to significant process problems even with small z-heights, such as contamination of the axes and the exposure unit's protective screen. There is a need for polymer particle powders that can be generated with the most uniform particle size distribution possible, so that relevant proportions of very small particles are avoided.

[0023] Another problem in processing polymer particle powders intended for powder bed fusion is the processing speed itself. Since polymers generally do not absorb radiation with shorter wavelengths, prior art technologies have used CO2 lasers (see above, which operate at a wavelength in the range of 10,600 nm), but these are not very attractive due to cost. Exposure systems that emit light with wavelengths in the range of 400 nm to 3,000 nm are significantly more cost-effective, allowing such systems to be used in larger quantities in powder-based 3D printing systems, which in turn enables faster overall processing.

[0024] Approaches have already been described for avoiding CO2 lasers by adding additives (also called absorbers) to polymer powders that absorb light with a wavelength in the near-infrared range (i.e., 780 nm to 3000 nm) and transfer it to the polymer particles. However, the addition of these additives themselves results in less favorable dusting behavior in such powders. To date, no polymer particle powders have been described that exhibit both favorable processing characteristics, particularly rapid deposition with the formation of flat and dense layers, and that, on the other hand, can be removed by exposure to light with a wavelength in the range of 400 nm to 3000 nm and / or in the range of 4800 to 8300 nm, as is the case, for example, with M / EOSG-033-PC.

[0025] 6

[0026] Diode laser systems can be provided and processed. Therefore, there is a need for polymer particle powders improved in this respect.

[0027] The present invention addresses this need.

[0028] Description of the invention

[0029] In the investigations underlying this invention, it was surprisingly discovered that polymer particle powders with the desired properties can be produced by forming at least a relevant proportion of the polymer powder particles as essentially cylindrical particles containing an absorber that absorbs light in the wavelength range of 400 nm to 3000 nm and / or in the range of 4800 to 8300 nm. Here, the term "contains" refers to the fact that the absorber is integrated into the particles and embedded in a matrix of the polymer that forms the polymer powder particles. In this way, the polymer powder itself does not contain any very small particles that could lead to increased dust formation during processing.

[0030] Accordingly, according to a first aspect, the present invention relates to a polymeric powder for use as a building material for the additive manufacturing of a three-dimensional object by selective solidification of a building material at the cross-sectional surfaces of the three-dimensional object in the corresponding layers, wherein the polymeric powder has a proportion of substantially cylindrical particles of at least 40 wt.%, based on the total weight of the particles, and the particles contain an absorber that absorbs light in the wavelength range of 400 nm to 3000 nm and / or in the range of 4800 to 8300 nm, and wherein the powder has a dust index of 15 or less and / or a dust area of ​​50 or less.

[0031] The specification of "at least 40 wt.%" indicates that the polymeric powder contains a relevant proportion of essentially cylindrical particles, with a higher particle count offering advantages in terms of greater uniformity and, consequently, more stable formation of flat and denser layers at high application rates. Accordingly, a proportion of at least 50 wt.% is required according to the invention, further M / EOSG-033-PC

[0032] 7. Preferably at least 60 wt.%, more preferably at least 70 wt.%, more preferably at least 80 wt.%, more preferably at least 90 wt.%, and more preferably at least 95 wt.%, of substantially cylindrical particles are contained in the claimed polymeric powder. In a particularly preferred embodiment, the polymeric powder is formed exclusively from substantially cylindrical particles.

[0033] "Essentially cylindrical" refers to the fact that, during the production of such powders, it is often not possible for every particle to have a perfectly cylindrical shape. For example, if the essentially cylindrical particles are produced by cutting fibers, the formation of cutting artifacts, which cause the shape of the particles to deviate from a perfectly cylindrical form, cannot be avoided. The term "essentially cylindrical" is therefore intended to ensure that particles with such cutting artifacts are also covered by the present invention.

[0034] In the context of the invention described herein, an absorber is understood to be a material that absorbs light with a wavelength in the range of 400 nm to 3000 nm and / or in the range of 4800 to 8300 nm and converts it into heat. This heat can then be transferred to the polymer of the plastic powder. In contrast to conventional processing of plastic powders, the invention therefore does not involve heating, or only to a minor extent, the polymer that forms the plastic powder, but rather, in a first step, the absorber, which subsequently transfers the absorbed energy to the polymer of the plastic powder.

[0035] The dustiness that the polymeric powder is intended to exhibit in the context of the invention described herein is an important characteristic of the powder. This is achieved, on the one hand, by including essentially cylindrical particles and, on the other hand, by excluding very small particles, particularly in the form of relevant quantities of small-particle additives mixed into the polymeric powder. In a preferred embodiment, the polymeric powder therefore contains less than 0.1 wt.% of separate particle components with a particle size 100 times smaller than the particle size of the polymer particles in the powder, and less than 1 wt.% of separate particle components with a particle size of M / EOSG-033-PC.

[0036] 8

[0037] The particle size is 20 times smaller than the particle size of the polymer particles in the powder. Particle sizes are to be determined in the context of the invention described herein by laser diffraction in accordance with ISO 13320.

[0038] The dusting behavior, as described herein, is measured using the dust index and / or the dust area, which are to be determined according to the invention using a dust measuring device. In the context of this invention, the dust index and the dust area were determined, in particular, using a DustMon RD 100 from Retsch GmbH, which serves as a reference. Further details for determining the parameters are given below in the example section.

[0039] For the polymeric powder according to the invention, it is preferred that it has a dust index of 12 or less, and preferably in the range of 10 or less, and / or 1 or more, and / or 2 or more. Alternatively or additionally, it is preferred that it has a dust area of ​​40 or less, and preferably 25 or less, and / or 2 or more, and preferably 5 or more. The preferred lower limit results from the fact that a lower dust index or a smaller dust area is difficult to achieve or can only be achieved with considerable additional technical effort.

[0040] For the polymeric powder according to the invention, it is preferred that the particles, which have a substantially cylindrical shape, exhibit a particle length distribution range (“PLDS”) of no more than approximately 1.2, where PLDS is equal to (L80-L20) / L50. Here, L80, L50, and L20 denote the particle lengths at which 80%, 50%, and 20% of the particles, respectively, have a length smaller than the specified length. These dimensions are determined microscopically by measuring the lengths of a suitable number of particles (e.g., 100). A smaller distance between L20 and L80 and L50 results in a smaller difference between L80 and L20, consequently leading to a smaller PLDS. Therefore, a smaller PLDS value indicates a narrower particle length distribution overall than a larger PLDS value.For the particle length distribution range, it is preferred, in the sense of a narrower distribution of particle lengths, if it is no more than 1.1, in particular no more than 1.0, more preferably no more than 0.90, and even more preferably no more than M / EOSG-033-PC.

[0041] 9 is 0.80, more preferably not more than 0.70, more preferably not greater than 0.60, more preferably not greater than 0.50, more preferably not greater than 0.40, more preferably not greater than 0.30, more preferably not greater than 0.20, more preferably not greater than 0.10, or even not greater than 0.05. In most cases, a value of 0.01 or 0.03 can be specified as the lower limit for the particle length distribution range.

[0042] In another embodiment, the powder according to the invention contains up to 50 wt.% spherical (i.e., substantially globular) particles, wherein a proportion of 1 to 40 wt.% is preferred, a proportion of 2 to 30 wt.% is further preferred, and a proportion of 5 to 25 wt.% is even more preferred. For mixtures of spherical and substantially cylindrical particles, it is preferred if the particle sizes of the different particle shapes do not differ substantially from one another, and the d50 particle size of the spherical particles is at most a factor of 2 larger or smaller than the particle size of the substantially cylindrical particles. These respective particle sizes are to be determined by laser diffraction. A deviation of at most a factor of 1.8 larger or smaller is further preferred, at most a factor of 1.5 larger or smaller, and at most a factor of 1.3 larger or smaller.

[0043] The non-spherical particles can be produced by methods known to the skilled person for the production of such particle powders, including, but not limited to, precipitation, production in a gas / dispersion reactor, milling of larger particles, melt dispersion, underwater extrusion or multi-stage mixed processes for the production of corresponding polymer particle powders.

[0044] Any material is suitable as an absorber that exhibits a higher absorption (determined photospectrometrically at identical layer thickness) at the incident wavelength (in the range of 400 nm to 3000 nm or in the range of 4800 to 8300 nm) than the polymer that forms the particles of the polymeric powder in which the absorber is embedded. Examples of usable absorbers include metal particles, organic dyes, pigments (e.g., inorganic pigments or carbon black), salts, minerals, or mixtures of different absorber types. M / EOSG-033-PC

[0045] 10

[0046] A preferred absorber in the invention described herein is carbon black, since carbon black exhibits high absorption even at comparatively low concentrations. Particularly suitable types of carbon black for use as absorbers are, for example, those with one or preferably both of the properties described below:

[0047] (i) amorphous industrial carbon black (definition according to EC No. 215-609-0, CAS No. 1333-86-4), preferably with a mean primary particle size, determined by laser diffraction, in the range of 26 to 58 nm;

[0048] (ii) Soot with a carbon content of more than 96% (according to elemental analysis).

[0049] Particularly preferred types of carbon black for use as absorbers in core materials are those described in WO 2020 / 099236 Al.

[0050] Carbon black is particularly suitable as an absorber for applications where the color of a product made from the material is less relevant, since carbon black, due to its inherent color, usually results in a grey tone in the powder and products made from it.

[0051] Other materials that can be used as absorbers in the particles of the polymeric powders according to the invention are metal hexaborides MB6, in particular selected from the group comprising yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, strontium or calcium hexaboride, metal oxides, in particular in the form of cesium tungsten oxide, metal phosphates and / or metal phosphites, in particular orthophosphates, polyphosphates, pyrophosphates or hydroxide phosphates, such as in particular copper hydroxyide phosphate (KHP), or graphite.

[0052] In one embodiment, the absorber is carbon black. In another embodiment, the absorber is a non-black substance, preferably a light-colored substance such as LaB6 or copper hydroxide phosphate. The absorber can also be a substance that additionally acts as a flame retardant. M / EOSG-033-PC

[0053] 11

[0054] The absorber is preferably incorporated into the polymeric powder according to the invention in an amount sufficient to ensure adequate melting of the particles by light exposure during processing. A suitable amount of absorber can be specified as being in the range of 0.02 wt.% to 3 wt.%, and particularly 0.05 wt.% to 1 wt.%. Carbon black and absorbers based on metal hexaborides exhibit particularly favorable absorption efficiency, so that such absorbers are preferably used in smaller amounts, e.g., in the range of 0.02 wt.%, and particularly 0.05 wt.% to 0.3 wt.%, while less efficient absorbers, such as metal phosphates and / or metal phosphites, are usually incorporated into the polymeric powders in larger amounts, e.g., 0.2 wt.%, and particularly 0.5 wt.%.

[0055] The essentially cylindrical particles used in the polymeric powders according to the invention can be advantageously produced by spinning a polymer mixture, which consists of the polymer and the absorbers and optionally further additives, e.g. in the form of flame retardants, into fibers and cutting the generated fiber to produce the particles. A guillotine cutting system, for example, can be used for cutting the fibers.

[0056] The polymer on which the polymeric powder according to the invention is based is not subject to any relevant restrictions in the context of the invention described herein, provided that it is a thermoplastic polymer that can be liquefied / melted by absorbing energy and subsequently solidifies into a compact body upon cooling. Homopolymers, copolymers, or polyblends (also referred to as "polymer blends") can be used for this purpose. A polyblend is understood to be a mixture of two or more different polymers. A polyblend can be a single-phase polyblend (homogeneous polyblend) or a multi-phase polyblend (heterogeneous polyblend). In a multi-phase polyblend, several glass transitions are typically observed by differential scanning calorimetry.

[0057] The polymer can be made from thermoplastic elastomers, polyaryletherketones (PAEK), polyarylethersulfones (PAES), polyamides, polyesters, polyethers, M / EOSG-033-PC

[0058] 12

[0059] Polylactides (PLA), polyolefins, polystyrenes, polyphenylene sulfides, polyvinylidene fluorides, polyphenylene oxides, polyimides, polyetherimides, polycarbonates, polyurethanes, polysulfones, polyketones, polyacetals, polysiloxanes and copolymers comprising at least one of the aforementioned polymers or their monomer units, as well as polymer blends of one or more of the aforementioned polymers or copolymers thereof, are selected, but the selection is not limited to the aforementioned polymers and copolymers and polymer blends thereof.

[0060] Suitable PAEK polymers and copolymers, for example, are selected from the group consisting of polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherketone (PEK), polyetheretherketoneketone (PEEKK), polyetherketoneetherketoneketone (PEKEKK), polyaryletheretheretherketone (PEEEK) and copolymers that include at least one of the aforementioned polymers.

[0061] Suitable polyamide polymers or copolymers may be selected from the group consisting of polyamide 6 / 6T, polyamide elastomers such as polyether block amides (e.g., PEBAX™-based materials), polyamide 5, polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 510, polyamide 612, polyamide 610, polyamide 1010, polyamide 1012, polyamide 1212, polyamide PA6T / 66, PA4T / 46, and copolymers that include at least one of the aforementioned polymers. Suitable polyester polymers or copolymers may be selected from polyalkylene terephthalates (e.g., PET, PBT) or polyarylent terephthalates and their copolymers. Suitable polyolefin polymers or copolymers may be selected from the group consisting of polyethylene, polypropylene, and polybutylene. Suitable polystyrene polymers or copolymers can be selected from the group consisting of atactic, syndiotactic and isotactic polystyrenes.Suitable polyimide polymers or copolymers can be selected from the group consisting of polyarylamide, polybismaleimide, and especially polyetherimide. Suitable copolymers include, for example, acrylonitrile-butadiene-styrene (ABS) copolymer, styrene-acrylonitrile (SAN) copolymer, or acrylonitrile-styrene acylate (ASA) copolymers. In one formulation, copolyesters in combination with carbon black as an absorber material as the base of the specified polymeric powders are excluded from the scope of protection. M / EOSG-033-PC.

[0062] 13

[0063] In a further embodiment of the invention, the particles of the polymeric powder according to the invention are formed from polymers or copolymers or blends of PAEK, polyamide, or polyetherimide, wherein the PAEK is preferably PEEK, PEKK, PEK, PEEKK, PEKEKK, and / or PEEEK, and the preferred polyamide is polyamide 12 and / or polyamide 11. In a further preferred embodiment, the particles of the polymeric powder according to the invention comprise a polypropylene polymer or a polypropylene / polyethylene copolymer as the polymeric component.

[0064] In a further preferred embodiment, the particles of the polymeric powder according to the invention are formed from polyamide polymers or copolymers, in particular polyamide 12, polyamide 11 and / or polyamide 1012 and / or a copolymer comprising at least one of the aforementioned polymers or their monomer units, and / or at least one polymer blend comprising at least one of the aforementioned polymers or copolymers. Alternatively, it is preferred that the particles of the polymeric powder according to the invention comprise polyolefins, e.g., in the form of polyethylene, polypropylene or polybutylene, polystyrene, polyester, polycarbonate, acrylonitrile butadiene styrene (ABS) copolymer, styrene acrylonitrile (SAN) copolymer, an acrylonitrile styrene acylate (ASA) copolymer, polyetherimide, a thermoplastic polyurethane, or a block copolymer of polyamide and polyethers (also referred to as polyether block amide or PEBA).

[0065] In a further preferred embodiment, the particles of the polymeric powder according to the invention are formed from polymers selected from the group comprising thermoplastic elastomer, polypropylene, polyetherimide, and polyetherketone ketone.

[0066] The particle size of the polymer powder according to the invention is within a range suitable for processing polymer powders in 3D production processes, with a particle size in the range of 20 to 100 pm, and in particular at least 25 pm and / or at most 80 pm, and more preferably at least 30 pm and / or at most 60 pm, being particularly suitable. This particle size is determined by laser diffraction according to ISO 13320. M / EOSG-033-PC

[0067] 14

[0068] The polymeric powder can have a unimodal or monomodal particle size distribution, i.e., the particle size distribution exhibits a maximum. In this case, it is further preferred if the mean particle size is in the range of 30 to 60 pm. Alternatively, it is also preferred if at least 80% of the particles have a particle size in the range of ± 10 pm relative to the mean particle size of the polymeric powder, which characterizes a narrow particle size distribution.

[0069] In a further preferred embodiment, the polymeric powder according to the invention has a bi- or multimodal particle size distribution, wherein "bimodal" here refers to the fact that the particle size distribution has two maxima, while in the case of a multimodal particle size distribution more than two maxima can be detected in the particle size distribution.

[0070] As mentioned above, for the sake of minimizing dust generation during processing, application, or transfer, it is advantageous for the polymeric powder to contain no or only very small amounts of substances with a particle size smaller than that of the polymeric powder. Substances that, on the other hand, positively influence the flow behavior of the powder are not excluded according to the invention and may also be present in the powder in small amounts as separate particles. Such additives include, for example, flow agents (e.g., Aerosil 200). The amount of such flow agents is generally no more than 1% by weight, preferably at least 0.01% and / or a maximum of 1% by weight, more preferably at least 0.025% by weight and / or a maximum of 0.5% by weight, and even more preferably at least 0.05% by weight and / or a maximum of 0.4% by weight.

[0071] Additives, which may preferably be incorporated into the particles of the polymeric powders together with the absorbers, include thermostabilizers, reflective particles (e.g., in the form of TiCh), flame retardants, discoloration inhibitors, lubricants, nucleating agents, thickeners, antioxidants (e.g., N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], which is commercially available from BASF as Irganox 1098), antistatic agents, biodegradability and / or biocompatibility enhancers, preservatives, dyes, fragrances, hydrolysis stabilizers, or plasticizers. Fillers and / or reinforcing fibers, preferably M / EOSG-033-PC

[0072] 15. The particles of the polymeric powders that may be included together with the absorbers include, among others, metal particles, mineral and / or ceramic fillers or glass beads, glass and / or carbon fibers.

[0073] Another aspect of the present invention relates to a method for producing a three-dimensional object, in particular by solidifying a powdered building material at the points or surfaces that correspond to the cross-section of the three-dimensional object in the respective layer, wherein a polymeric powder as described above is used as the building material and preferably the building material is selectively solidified by the action of electromagnetic radiation emitted from a radiation source.

[0074] Within the scope of the described process, it is preferred that the respective layer is produced by applying the polymer powder to a surface, either to a substrate or to one or more layers already present on the substrate, using an application device, and that the application device is operated at a speed of at least 300 mm / s. This application speed is higher than that of known processing methods, which are associated with difficulties in applying flat and dense particle layers. On the other hand, due to the particle shape and composition of the polymer powders according to the invention, uniform layers can be applied even at high application speeds without significant dust formation.The process can therefore also be operated with application speeds that are significantly higher than 300 mm / s, such as in particular at least 400 and / or at most 800 mm / s and more preferably at least 500 and / or at most 700 mm / s.

[0075] A further aspect of the present invention relates to a system for producing a three-dimensional object by solidifying a powdered building material at the points or surfaces corresponding to the cross-section of the three-dimensional object in the respective layer, wherein the system comprises at least one radiation source configured to emit electromagnetic radiation, a process chamber configured as an open container and having a container wall, and a support located in the process chamber, wherein the process chamber and the M / EOSG-033-PC

[0076] 16

[0077] The system comprises two carriers movable relative to each other in a vertical direction, and a storage container and coating unit movable in a horizontal direction, the storage container being at least partially filled with a polymeric powder as described above. This system consists of two relevant components: firstly, a device in which the polymeric powder is processed, and secondly, the polymeric powder itself, which is stored in the device. Accordingly, the claim relates not to the device as such, but only to the device in a specific state in which it exists in combination with the powder according to the invention (analogous to a kit comprising both components).

[0078] The radiation source in the prescribed method and the corresponding system is preferably a radiation source that emits electromagnetic radiation with a wavelength in the range of 500 to 1500 nm, and more preferably in one of the wavelength ranges of 1064 ± 10 nm and / or 980 ± 10 nm and / or 940 ± 10 nm and / or 810 ± 10 nm and / or 780 ± 10 nm and / or 640 ± 10 nm. For the specified deviation “± 10 nm”, a range of ± 7 nm is considered preferred and a range of ± 5 nm is considered particularly preferred.

[0079] Alternatively, the radiation source is a radiation source that emits electromagnetic radiation with a wavelength of 4800 to 8300 nm and in particular about 5 pm.

[0080] Additionally or alternatively, it is preferred if the radiation source comprises at least one laser, preferably at least one diode laser.

[0081] Within the scope of the present invention, the terms "comprising" or "containing" and their grammatical variations have the following meanings: In one embodiment, additional elements may be included besides those mentioned. In another embodiment, essentially only the elements mentioned are included. In other words, in addition to their conventional meaning, the terms may, in a particular embodiment, be synonymous with the terms "essentially consisting of" or "consisting of". M / EOSG-033-PC

[0082] 17

[0083] Embodiments described above as preferred for one particular aspect shall also be considered preferred and described for all other aspects, provided that no obvious contradictions arise from the combination.

[0084] Figure 1 shows an example of a conventional laser sintering device for the layer-by-layer production of a three-dimensional object.

[0085] The advantages realized by the present invention can be summarized as follows:

[0086] The powder morphology and structure significantly improve powder feeding (i.e., powder supply and application). Since the powder according to the invention can be conveyed with less shear (e.g., caused by high-flow fluidization) and processed on additive manufacturing systems, dust generation is substantially reduced.

[0087] The powder morphology and structure further enable a more homogeneous and denser powder bed, resulting in optimized process capability and improved component properties (especially in terms of mechanical properties, surface quality, and accuracy / functionality).

[0088] The powder morphology and structure result in a lower tendency for the powder to accumulate an electrostatic charge. A homogeneous equilibrium (temperature and / or humidity) can be reached more quickly.

[0089] The present invention will be illustrated in more detail below by means of some examples, which, however, should not be regarded as limiting the scope of protection of the application in any way.

[0090] Examples:

[0091] All the tests described below were performed on an LPF P 500 system with a nearly identical machine setup. The two main influencing factors for dust generation in the process chamber are the M / EOSG-033-PC

[0092] 18

[0093] Coater speed and the fluidization setting of the powder application module were adjusted. These parameters were set to a constant 600 mm / s (coater speed) and between 7-12 l / min (fluidization). The build job height was always at least 150 mm or at least 1500 layers.

[0094] Dust development in the process chamber was visually assessed during and after the construction process based on the deposits within the chamber. Additionally, dust measurements were performed on the powder samples using the DustMon RD100 from Retsch GmbH to analytically confirm the subjective observations (see method description).

[0095] The DustMon RD 100 assesses the dustiness of a polymer powder by measuring a sample dropped through a tube into a chamber. The dust released upon impact is measured using an LED detector based on light opacity, and the dustiness of the sample is quantified using the Dust Index and / or Dust Area. The Dust Index is a measure of the maximum dust generation, while the Dust Area indicates the area of ​​the evaluation graph over a given period. A smaller Dust Index or Dust Area indicates lower dust generation.

[0096] In the following tests, the respective dust indices and areas were determined using the DustMon RD100 at room temperature via at least three measurements. Each measurement used 20 g of material, and the time interval for determining the dust area was 30 seconds. The value reported was the mean of three measurements. After each measurement, the downpipe and chamber were thoroughly cleaned with a vacuum cleaner. Moisture and any agglomerates present in the samples can significantly influence the results; therefore, the moisture content of the materials was measured and recorded. The Testo 635-2 temperature and humidity meter with its corresponding probe for relative humidity and air temperature measurements was used. The humidity consistently ranged from 30% to 60%. M / EOSG-033-PC

[0097] 19

[0098] The following describes four reference examples in which powders produced by conventional powder manufacturing were processed and analyzed. The following embodiments 1 and 2 were produced by manufacturing polymer fibers and subsequently cutting the fibers into pieces approximately 50 pm long.

[0099] Reference example 1

[0100] Polyamide-12 powder of type PA 2200 from EOS GmbH was dosed in the machine without the addition of further additives (i.e., in particular without absorbers) and applied to the build area with the recoater (i.e., without exposure).

[0101] Reference example 2

[0102] A mixture of polyamide 12 powder and special black 4 from Orion Engineered Carbons GmbH, acting as a soot absorber (where the soot adheres to the PA12 particle surface), was used as the starting material. The plastic powder was metered in the machine, applied to the build platform with the recoater, and cured multiple times.

[0103] Reference example 3

[0104] Polyamide 11 powder with absorber was dosed in the machine, applied to the build area with the recoater and exposed.

[0105] Reference example 4

[0106] A mixture of polyamide 12 powder with incorporated carbon black as absorber (VESTOSINT® DP 10035 bk) from Evonik Operations GmbH was dosed in the machine, applied to the build area with the coater and exposed.

[0107] Example 1

[0108] Polyetherimide powder (50:50 mixture of Ultem 1010 and 1040A) was processed into filaments with 0.1 wt% carbon black (Mogul L) as an absorber and subsequently cut into particles approximately 50 pm long. The resulting M / EOSG-033-PC

[0109] 20

[0110] Powder was dosed in the machine and applied to the build area with the recoater (without exposure).

[0111] Example 2

[0112] Polyetherimide powder (a 50:50 mixture of Ultem 1010 and 1040A) was processed into filaments with 0.75 wt% Iriotec 8850 as an absorber and then cut into particles approximately 50 pm long. The resulting powder was metered into the machine and applied to the build platform with the recoater (without exposure).

[0113] The results and observations from the processing of the plastic powders are given in the following table. M / EOSG-033-PC

[0114] 21

[0115] As can be seen from the table provided, the plastic powders according to the invention show a significantly reduced dust formation compared to conventionally produced plastic powders.

Claims

M / EOSG-033-PC 22 Claims 1. Polymeric powder for use as a building material for the additive manufacturing of a three-dimensional object by selective solidification of a building material on the cross-sectional surfaces of the three-dimensional object in the corresponding layers, wherein the polymeric powder has a proportion of substantially cylindrical particles of at least 40 wt.%, based on the total weight of the particles, and the particles contain an absorber that absorbs light in the wavelength range of 400 nm to 3000 nm and / or in the range of 4800 to 8300 nm and wherein the powder has a dust index of 15 or less and / or a dust area of ​​50 or less.

2. Polymeric powder according to claim 1, wherein the substantially cylindrical particles of the powder have a particle length distribution range (PLDS) of not more than 1.2, wherein PLDS is equal to (Lso-Lzo / Lso, where L80, L50 and L20 denote the particle length at which 80%, 50% and 20% of the particles are smaller than the specified length, respectively.

3. Polymeric powder according to claim 1 or 2, wherein the powder has a dust index of 12 or less and preferably in the range of 2 to 10 and / or a dust area of ​​40 or less and preferably in the range of 5 to 25.

4. Polymeric powder according to claims 1 to 3, wherein the absorber is selected from the group comprising metal hexaborides MB6, in particular selected from the group comprising yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, strontium or calcium hexaboride, metal oxides, in particular in the form of cesium tungsten oxide, metal phosphates and / or metal phosphites, in particular orthophosphates, polyphosphates, pyrophosphates or hydroxide phosphates, graphite and carbon black, in particular in the form of carbon black.

5. Polymeric powder according to one of the preceding claims, wherein the absorber is included in the particles in an amount of 0.02 wt.% to 3 wt.%, in particular 0.05 wt.%. M / EOSG-033-PC 23 6. Polymeric powder according to one of the preceding claims, wherein the substantially cylindrical particles are produced by spinning a polymer mixture into fibers and cutting the generated fiber to generate the particles.

7. Polymeric powder according to one of the preceding claims, wherein the powder is based on a polymer selected from the group comprising thermoplastic elastomer, polypropylene, polyethyleneimide, polyetherketone ketone as the polymeric component.

8. Polymeric powder according to one of the preceding claims, wherein the powder has a mean particle size, determined by laser diffraction, in the range of 20 to 100 pm, preferably 25 to 80 pm and more preferably 30 to 60 pm.

9. Polymeric powder according to one of the preceding claims, wherein the powder has a unimodal particle size distribution, preferably with a mean particle size in the range of 30 to 60 pm, wherein further preferably at least 80% of the particles have a particle size in the range of ± 10 pm to the mean particle size of the polymeric powder.

10. Polymeric powder according to any one of claims 1 to 7, wherein the powder has a bi- or multimodal particle size distribution.

11. Polymeric powder according to any one of the preceding claims, wherein the powder additionally contains one or more flow agents and / or fillers and / or fibers and / or, in addition to the absorber, one or more additives selected from the group comprising thermostabilizers, reflective particles, flame retardants, discoloration inhibitors, lubricants, nucleating agents, thickeners, antioxidants, antistatic agents, biodegradability and / or biocompatibility enhancers, preservatives, dyes, fragrances, hydrolysis stabilizers and plasticizers are incorporated into the particles of the polymeric powder.

12. Method for producing a three-dimensional object, in particular by solidifying a powdered building material at the points or surfaces corresponding to the cross-section of the three-dimensional object in the respective layer, wherein a polymeric powder according to a M / EOSG-033-PC 24 of claims 1 to 11 is used as a building material and preferably the building material is selectively hardened by the action of electromagnetic radiation emitted from a radiation source.

13. Method according to claim 12, wherein the respective layer is produced in such a way that the polymer powder is applied to a surface by means of an application device onto a carrier or onto one or more layers already located on the carrier, and the application device is operated at a speed of at least 300 mm / s, preferably in the range of 400 to 800 mm / s and more preferably 500 to 700 mm / s.

14. System for producing a three-dimensional object by solidifying a powdered building material at the points or surfaces corresponding to the cross-section of the three-dimensional object in the respective layer, wherein the system comprises at least one radiation source designed to emit electromagnetic radiation, a process chamber designed as an open container and having a container wall, a support located in the process chamber, wherein the process chamber and the support are movable relative to each other in a vertical direction, and a storage container and coater movable in a horizontal direction, wherein the storage container is at least partially filled with a polymeric powder according to at least one of claims 1 to 11.

15. Method according to claim 12 or 13 or system according to claim 14, wherein the radiation source emits electromagnetic radiation of a wavelength in the range of 400 to 3000 nm, preferably 500 to 1500 nm, and further preferably in one of the wavelength ranges 1064±10 nm and / or 980± 10 nm and / or 940±10 nm and / or 810±10 nm and / or 780±10 nm and / or 640±10 nm.

16. Method according to claim 11, 12 or 14 or system according to claim 13 or 14, wherein the radiation source comprises at least one laser, preferably at least one diode laser.

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