Method for processing amorphous materials in powder-based additive manufacturing

Abstract

The present invention relates to methods for producing three-dimensional objects (3) from powdered amorphous thermoplastics in powder-bed-based additive manufacturing, in which the radiation source (7) allows planar exposure and the plastic powder has increased absorption compared to conventional plastic powders. The invention further relates to plastic powders that are formulated for use in corresponding methods, to methods for producing such plastic powders, to correspondingly produced three-dimensional objects that can be produced according to the specified method, and to systems for producing such three-dimensional objects. By adding an absorber to the amorphous polymer, an improved heating behaviour of the amorphous polymer is achieved, which allows such polymers to be processed using planar exposure systems without semi-crystalline or crystalline polymers having to be added for this purpose.

Description

[0001] September 27, 2024

[0002] EOS GmbH Electro Optical Systems M / EOSG-025-PC PF / CBE / cbe

[0003] Methods for processing amorphous materials in powder-based additive manufacturing

[0004] Description

[0005] The present invention relates to methods for producing three-dimensional objects from powdered amorphous thermoplastics using powder bed fusion additive manufacturing, in which the radiation source allows for planar illumination and the plastic powder exhibits increased absorption compared to conventional plastic powders. The present invention further relates to plastic powders prepared for use in such methods, methods for producing such plastic powders, three-dimensional objects produced accordingly that can be manufactured according to the specified method, and systems for producing such three-dimensional objects.

[0006] State of the art

[0007] Methods for the layer-by-layer construction of three-dimensional objects using polymer powders, in which the object is built up layer by layer by applying powder layers and melting / solidifying layer areas by means of electromagnetic radiation, which after production form the three-dimensional object, are known, for example, from DE 44 10 046. Such a method for producing three-dimensional objects is also referred to as "additive manufacturing".

[0008] When energy is applied to melt the plastic powder during processing, homogeneous energy absorption poses a significant challenge. The applied energy must be sufficient to melt and adequately liquefy the powder material in the targeted area, concentrating a large amount of energy into a relatively small space. If the energy absorption is not homogeneous, hot spots can easily form, where M / EOSG-025-PC

[0009] 2. The polymer is degraded or even decomposed, which consequently has a negative impact on the mechanical properties of the object. To counteract this, processing usually takes place in a closed and temperature-controlled chamber (also called a "build chamber") where the temperature can be set to just below the polymer's melting point. During subsequent processing, the amount of energy radiated to liquefy the polymer material can then be minimized.

[0010] Some polymers of interest for additive manufacturing, such as polyetherimide, which is highly temperature-resistant and transparent, form only amorphous particles when produced using conventional methods. A problem with amorphous polymer materials is that they can only be heated to their glass transition temperature (or slightly above), as the powder particles clump together at temperatures above this point. This prevents uniform powder deposition and reduces component quality. Furthermore, it negatively impacts the detail definition of the manufactured components. Consequently, amorphous polymer materials have not yet been used in powder bed fusion processes or for the production of dense, mechanically robust components.

[0011] Amorphous polymers must therefore be heated from their glass transition temperature to well above their melting point, requiring a significantly higher energy input from the secondary energy source (e.g., a laser, infrared emitter, etc.) to achieve a sufficiently fluid polymer melt. This process is much more likely to damage the material. A gentler manufacturing method (using lower-power energy input over a longer period) is also not economically viable because it drastically slows down the production of the object.

[0012] To enable the processing of amorphous polymers via selective laser melting or laser sintering, several approaches have already been described in the prior art. For example, WO 2018 / 046582 A1 describes the processing of a mixture of a semi-crystalline and an amorphous polymer, to which a compatibility enhancer is added to form the product M / EOSG-025-PC.

[0013] 3. To ensure a homogeneous mixture of the polymers. The combination with the semi-crystalline polymer component is intended to overcome the problems observed when processing only amorphous polymers, namely the comparatively porous products and the resulting, usually insufficient, mechanical strength.

[0014] WO 2014 / 151500 A1 describes the production of precipitating powders from amorphous polyetherimide (Ultem 1000) by producing an emulsion of the polymer in a mixture of organic solvent and water, introducing the generated emulsion into deionized water and subsequently condensing off the organic solvent.

[0015] In another approach, melt-amorphous polymers can be treated in such a way that partial crystalline structure is achieved, e.g., through dissolution or swelling of the polymers (see, e.g., WO 2016 / 209870). However, such an approach is not feasible with all amorphous polymers.

[0016] Against this background, there is a need for a way to modify the melting behavior of amorphous polymers during processing using additive manufacturing techniques in such a way that even when higher energy levels are applied to melt the polymer powder particles, undesirable degradation and decomposition of the polymer is avoided, allowing the material to be processed without reducing the build speed or energy input. Ideally, such a technology should enable the production of objects with good surface quality (e.g., low porosity) and dimensional stability.

[0017] This is particularly relevant given that newer generations of processing systems for the production of three-dimensional objects use planar exposure systems to accelerate production, enabling faster processing and manufacturing.

[0018] The present invention addresses this need.

[0019] Detailed description of the invention M / EOSG-025-PC

[0020] 4

[0021] The investigations underlying this application surprisingly revealed that improved and more uniform melting behavior of a polymer or plastic powder can be achieved by modifying the plastic powder with a radiation absorber. The absorber can be present as a discrete additive along with the plastic particles, incorporated into the plastic particles, or a combination of both. This allows for the development of readily available area exposure systems for processing the powders. The absorber is incorporated into the plastic powder in such an amount that the powder exhibits an absorption at the wavelength of the radiation source used that is at least twice that of an analogous powder without an absorber.

[0022] Accordingly, the present invention relates in a first aspect to a method for producing three-dimensional objects from powdered amorphous thermoplastics in powder bed-based additive manufacturing according to claim 1, i.e., a method wherein

[0023] - the powdered amorphous thermoplastic is applied layer by layer to a carrier system,

[0024] - the powdered amorphous thermoplastic is preheated to a processing temperature in the range of the softening temperature, in particular in the range Tg-20°C to Tg+20°C, by a heat source,

[0025] - the powdered amorphous thermoplastic is solidified by a radiation source at the corresponding points in the cross-section of the three-dimensional object in the respective layer,

[0026] - the radiation source allows for area-wide illumination, and

[0027] - the plastic powder has an absorption of at least 2 times that of the pure polymer, preferably at least 3 times, particularly preferably at least 5 times that of the pure polymer in the range of the wavelength of the radiation source used.

[0028] Advantageous embodiments of the method according to the invention are specified in dependent claims 2 to 5. M / EOSG-025-PC

[0029] 5

[0030] According to a second aspect, the present invention relates to a plastic powder for use in such a process according to claim 6, wherein the plastic of the plastic powder is formed from an amorphous polymer and the plastic powder has an added absorber which is preferably incorporated into powder particles and / or is present on their surface.

[0031] Advantageous embodiments of the plastic powder according to the invention are specified in dependent claims 7 to 11.

[0032] According to a third aspect, the present invention relates to a method for producing such plastic powders according to claim 12, in a fourth aspect a three-dimensional object according to claim 13, and in a fifth aspect a system for producing shaped bodies in combination with the plastic powders according to the invention according to the second aspect stated.

[0033] In a plastic powder where the powder particles are largely composed of amorphous polymer, the improved melting behavior mediated by the absorber is most pronounced, since in this case processing must take place at a lower temperature than with mixtures of semi-crystalline and amorphous polymers that do not contain an absorber. In the context of the invention described here, it is therefore preferred if the polymer contained in the plastic powder is provided by amorphous polymer to at least 50 wt.%, particularly at least 60 wt.%, more preferably at least 70 wt.%, even more preferably at least 80 wt.%, and still more preferably at least 90 wt.%. It is especially preferred if the polymer powder contains exclusively amorphous polymer as the plastic component.

[0034] In the context of the invention described herein, an amorphous polymer is a polymer with a fusion enthalpy of less than 5 J / g and preferably less than 1 J / g. The fusion enthalpy is determined here by DSC according to ISO 11357-3:2018-03. In this context, polymers with amorphous and semi-crystalline components are not to be considered "amorphous" polymers within the meaning of the invention if such polymers have a fusion enthalpy of 5 J / g or more.

[0035] To ensure uniform particle fusion and dimensional stability, it must be ensured that the M / EOSG-025-PC

[0036] 6

[0037] The viscosity of the polymer is neither too high nor too low. Particularly suitable polymers exhibit a melt volume flow rate of 10 to 50 cm³ at a test temperature of 100°C above the glass transition temperature and a test weight of 5 kg. 3 / 10 min. The glass transition temperature can be determined, for example, by differential scanning calorimetry according to DIN EN ISO 11357-2; the relevant glass transition temperature in connection with this invention is the value Ti / 2. g Assuming that the particles have more than one glass transition temperature, the glass transition temperature with the highest temperature is decisive.

[0038] 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.

[0039] The statement "absorbs light with a wavelength in the range of 400 nm to 3000 nm" should be understood to mean that the absorber can absorb light with a wavelength in this range, but not that the absorber only exhibits absorption bands in this wavelength range. In other words, the term "absorber" also includes materials that, in addition to light with a wavelength in the range of 400 nm to 3000 nm, can also absorb light with a wavelength above 3000 nm and / or below 400 nm. Soot, for example, is such an absorber, as it absorbs light across a very broad wavelength range.

[0040] As mentioned above, it is not crucial whether the absorber is present discretely from the polymer particles of the plastic powder or as an absorber integrated into the powder particles. Accordingly, the absorber can be located within the polymer-based particles, on the surface of the polymer-based particles, or in both forms within the plastic powder. An absorber present discretely alongside the polymer particles has the advantage of simpler manufacturing, as the two components can be easily mixed, while integration (or "incorporation") offers the advantage of a uniform M / EOSG-025-PC.

[0041] 7

[0042] which brings with it particle material whose flow properties can be more easily controlled and adjusted.

[0043] The wavelength range specified above (400 nm to 3000 nm) offers the advantage that organic polymers in this range generally exhibit no significant self-absorption. Therefore, when irradiated with light of a specific wavelength within this range, the absorber can be selectively targeted and heated. In this way, the amount of absorber can always be adjusted, regardless of the polymer, to deliver the desired amount of thermal energy to the irradiated powder volume. This can be further enhanced by using a radiation source with a very narrow emission wavelength (especially a laser).Since lasers with certain emission wavelengths in the range of 400 nm to 3000 nm are commercially available, it is preferred if the absorber absorbs radiation of one of the wavelengths (1064 10) nm and / or (980110) nm and / or (940110) nm and / or (810110) nm and / or (640110) nm.

[0044] In an alternative embodiment, the absorber absorbs electromagnetic radiation with a wavelength in the range of 4800 to 8300 pm and in particular about 5 pm.

[0045] With regard to the chemical nature of the absorber, the present invention is not subject to any relevant restrictions, provided the absorber provides sufficient absorption in the specified wavelength range. For example, the absorber can be selected from the group consisting of carbon black, graphite, salts, metals and metal oxides, carbon fibers, as well as organic and inorganic color pigments, copper phosphate or copper hydroxyphosphate, chalk, and mica pigments. Mica pigments are pigments based on the natural mineral mica, coated with a thin layer of metal oxides, for example, titanium dioxide and / or iron oxide, and are available with a mean particle size distribution between 1 and 60 pm. Such mica pigments are commercially available, for example, from Merck under the trade name Iriodin®.Other materials that can be used as absorbers include titanium dioxide, kaolin, organic and inorganic color pigments, antimony(III) oxide, metal pigments, pigments based on bismuth oxychloride (e.g., Biflair series from Merck, high-gloss pigment), indium tin oxide (Nano ITO powder, from Nanogate Technologies GmbH or AdNa M / EOSG-025-PC).

[0046] 8 notm ITO of Degussa), AdNanotm Zinc Oxide (Degussa), Lantan Hexachloride or ClearWeld® (WO 2002 / 38677).

[0047] For a suitably homogeneous distribution of the absorbers in the plastic powder, it is advantageous if the density of the plastic powder (determined according to DIN EN ISO 1183) and the density of the absorber (preferably determined according to DIN EN ISO 3953-2011-05) are similar, and preferably do not differ from each other by more than 50%, and more preferably not by more than 20%. Since this requirement cannot generally be met by metals, in a preferred embodiment the absorber is not a metal. In another preferred embodiment, the absorber is not carbon fibers, which are sometimes used to improve the mechanical properties of plastic powders for processing by selective solidification.

[0048] A particularly suitable absorber that fulfills this requirement and is therefore preferred in the context of the invention described herein is carbon black, especially in the form of industrial carbon black (EC No. 215-609-9, CAS No. 1333-86-4), which is carbon black specifically produced as an industrial raw material. Industrial carbon black is, by its very nature, a modification of carbon with a high surface-to-volume ratio and is primarily used as a filler and as a black pigment. Preferably, the carbon content of the carbon black, especially the industrial carbon black, is at least 96% according to quantitative elemental analysis.

[0049] It is particularly preferred if the absorber, in the form of carbon black, is incorporated into the plastic powder according to the invention, which, when analyzed by rheometer at aeration of 1.0 mm / s, exhibits a power consumption of less than 200 mJ, preferably less than 170 mJ, and particularly less than 140 mJ. This property results in significantly improved process stability compared to other types of carbon black.

[0050] The power consumption is preferably determined according to standard ASTM D 7891, e.g., using a Freeman FT4 Powder Rheometer (manufacturer: Freeman Technology; software: C740). Air is blown into a cylindrical vessel through the bottom. Powder is added to the vessel, and the power consumption of a stirrer is measured. The stirrer's power consumption is measured at an air velocity of M / EOSG-025-PC.

[0051] 9

[0052] Aeration speed of 1.0 mm / s is used as the criterion. The vessel has the following dimensions: 50 mm x 260 ml (e.g., Split Vessel, No. 8329, designation C2001). A stirring tool with a 48 mm diameter is used (e.g., Blade Assembly, designation C211). The filling volume into the cylindrical vessel is 160 ml. The maximum shear rate ("tip speed") of the stirring tool used (48 mm diameter) is 20 mm / s. The aeration is carried out in five stages from 0.0 to 2.0 mm / s at a helical angle of 5° and a shear rate of 20 mm / s.

[0053] For some applications, carbon black as an absorber has the disadvantage of darkening the polymer, which may be undesirable. Therefore, for such applications, an absorber with a different inherent color (e.g., white, like TiÜ2) can be used in the plastic powder.

[0054] The amount of absorber to be included in the plastic powder according to the invention depends on the temperature difference between the glass transition temperature and the melting temperature of the polymer from which the plastic powder is formed, and on the amount of energy that can be irradiated without degrading or decomposing the polymer. Generally, however, the absorber is used in an amount (based on weight) that is significantly less than the amount of polymer in the plastic powder. Preferably, the weight fraction of the absorber, based on the total weight of amorphous polymer and absorber, is at least 0.01 wt.%, more preferably at least 0.05 wt.%, further preferably at least 0.1 wt.% and / or at most 10 wt.%, more preferably at most 5 wt.%, and more preferably at most 2 wt.%.

[0055] It is further preferred if the absorber is incorporated into the plastic powder in such an amount that at least 5% and at most 100% of the incident radiation is absorbed across the thickness of a layer formed from the plastic powder for selective solidification (e.g., 40 pm, 50 pm, or 60 pm). It is particularly preferred if the amount is adjusted so that approximately 30% to 95%, and especially approximately 50% to 80%, of the incident energy is absorbed, since in this case the excess energy can remelt lower layers and thus improve the bonding between the layers. M / EOSG-025-PC

[0056] 10

[0057] Alternatively or additionally, it is preferred if the plastic powder according to the invention contains the absorber in a proportion, based on the total weight of amorphous polymer and absorber, such that the ratio of absorption of the incident radiation by the absorber to absorption of the incident radiation by the amorphous polymer is at least 2, preferably at least 5, more preferably at least 10 (i.e., the absorber absorbs at least 2, 5 or 10 times the radiation that is absorbed by the polymer).

[0058] For the plastic powder according to the invention, it is further preferred if it has one or more of the following properties:

[0059] - a glass transition temperature Tg, measured by DSC, of ​​about 50 to 300 °C and preferably of at least 80 and / or at most 250 °C;

[0060] - a particle size D50, determined by laser diffraction, of at least 20 pm, preferably at least 30 pm, more preferably at least 40 pm, and / or at most 100 pm, preferably at most 80 pm and more preferably at least 60 pm;

[0061] - a distribution width (D90-D10) / D50 of less than 3, preferably less than 2 and further preferably less than 1 ;

[0062] - a sphericity greater than 0.6, preferably greater than 0.7, even more preferably greater than 0.8, particularly preferably greater than 0.9 (determined by dynamic image analysis according to ISO 13322-2; e.g. with a Retsch (now Microtrac) Camsizer XT);

[0063] - a BET surface, determined according to DIN ISO 9277, of less than 20 m² 2 / g, preferably less than 10 m 2 / g, preferably less than 5 m 2 / g and even more preferably less than 2 m 2 / g; a bulk density according to DIN EN ISO 60 of at least 0.35 g / cm³ 3, preferably at least 0.4 g / cm³ 3 , particularly preferably at least 0.45 g / cm² 3 and / or a maximum of 0.7 g / cm² 3 , preferably with a maximum density of 0.65 g / cm³.

[0064] The amorphous polymer contained in the plastic powder according to the invention, or forming it as a polymer component, is also not subject to any relevant restrictions, provided it has a fusion enthalpy within the range described above. Possible polymers that this M / EOSG-025-PC

[0065] 11

[0066] Examples of polymers that can meet this requirement include:

[0067] Polyetherimide (PEI), polyaryletherketone (PAEK), polyethersulfone (PES), polyphenylenesulfone (PPSU), polysulfone (PSU), polyamides, polyesters, polyethers, polylactide, polyolefins, polystyrene, polyphenylene oxide, polyimide, polycarbonate, polyvinyl chloride, acrylonitrile butadiene styrene (ABS), styreneacrylonitrile (SAN), polyacrylate, polymethacrylate, polyamide-imide, polyurethane, or mixtures of these polymers. The amorphous polymer may also be a copolymer containing at least monomer units of one of the aforementioned polymers and / or at least a polymer blend comprising at least one of the aforementioned polymers or copolymers.

[0068] A particularly preferred polymer type in the context of the invention described herein is polyetherimide. A polyetherimide with a mean molecular weight (Mw) of 20,000 to 100,000 g / mol is especially preferred. Commercially available polyetherimides that can therefore be preferably used in the plastic powder according to the invention include, for example, Ultem. tm 1010 or Ultem tm 1040.

[0069] As mentioned above, the plastic powder according to the invention is preferably composed predominantly of amorphous polymer, while crystalline or semi-crystalline polymers (as a further component of a mixture) are not included to a relevant extent. "Not included to a relevant extent" here refers to a proportion of a maximum of 10 wt.% of the total polymer mass and preferably a maximum of 5 wt.%. In this context, the phrase "not to a relevant extent" and the phrase "essentially free of" are synonymous. In a highly preferred embodiment, the plastic powder according to the invention is free of crystalline or semi-crystalline polymers. Furthermore, the present invention is characterized in that the amorphous polymers can be processed without the need to add reactive components such as crosslinking agents.Therefore, it is still preferred if the plastic powder according to the invention is free of such reactive components or crosslinking agents. M / EOSG-025-PC.

[0070] 12

[0071] Alternatively, semi-crystalline or crystalline polymers are added which do not essentially melt under the processing conditions used and are therefore to be regarded as fillers.

[0072] In addition to the absorber and the amorphous polymer, the plastic powder according to the invention can contain further components and additives for property control and optimization. Such additives include, for example, fibers, particularly in the form of organic fibers, glass fibers, wollastonite, carbon fibers, carbon nanotubes, glass beads, pigments, particularly in the form of calcium carbonate or titanium dioxide, flame retardants, UV stabilizers, and heat stabilizers. Such additives can be included in the plastic powder according to the invention individually or as a mixture of several of the aforementioned additives. The proportion of these additives is not limited to a relevant extent, although in most cases the total amount of additives is less than that of the amorphous polymer and preferably does not exceed 50% by weight, based on the total weight of the plastic powder.For fillers that can absorb or reflect radiation as such, it is further required that they should not be included in the plastic powder according to the invention in a proportion that opposes the absorption of the absorber in this plastic powder (i.e., if the absorber is incorporated into the plastic powder particles, for example, only small amounts of reflective filler should be contained in the particles).

[0073] Furthermore, additives to improve processing properties can be added to the plastic powder according to the invention, e.g., flow-modifying agents or antistatic agents. Pyrogenic silica is, for example, a suitable flow-modifying additive. The proportion of the flow-modifying agent can usually be very small; that is, in most cases it is sufficient if the flow-modifying agent is included in the plastic powder in an amount of less than 0.5 wt.% and, in particular, less than 0.1 wt.%.

[0074] As described above, the core of the invention described here consists in a modification of the plastic powder in such a way that the incident energy is absorbed to the greatest extent possible not by the polymer, but by an added absorber, which the M / EOSG-025-PC

[0075] 13

[0076] The energy is subsequently transferred to the plastic as heat energy. In this way, the energy can be transferred to the plastic gently (over a longer period than through radiation alone). This also allows higher amounts of energy to be introduced into the material, which are necessary for melting an amorphous polymer. In a further aspect, the present invention therefore also relates to the use of an absorber in a plastic powder comprising an amorphous polymer, preferably a plastic powder as described above, as a means that absorbs the substantial portion of the energy irradiated into the plastic powder and transfers it as heat to the amorphous polymer. In this way, the construction of a three-dimensional object is facilitated by selectively solidifying the build-up material at the locations corresponding to the cross-section of the three-dimensional object in the respective layer through the action of radiation.

[0077] According to the first aspect stated above, the present invention relates to a method for producing three-dimensional objects from powdered amorphous thermoplastics in powder bed-based additive manufacturing, as specified above, in which the powdered thermoplastic is applied layer by layer to a support system, preheated to a temperature in the range of the softening temperature and solidified by a radiation source at the locations corresponding to the cross-section of the three-dimensional object, wherein the radiation source allows planar illumination and the plastic powder has an absorption of at least 2 times that of the pure polymer in the range of the wavelength of the radiation source used.

[0078] The requirement that the radiation source allows for area-wide exposure is to be interpreted as meaning that the radiation source is operated in such a way that the polymer powder is exposed to an area during the process. In other words, the process does not involve exposure where a light beam sequentially scans the areas to be solidified, but rather where a larger area of ​​the plastic powder is always exposed at any given time. This area can be linear, with the area to be solidified being M / EOSG-025-PC in a single layer.

[0079] 14 by guiding the linear beam over the surface to be consolidated, or in a planar manner in such a way that the light source illuminates a part of the surface to be consolidated in a layer with an extent in the x and y directions or the entire surface to be consolidated in a layer simultaneously.

[0080] Preheating the powdered amorphous thermoplastic to a processing temperature close to its softening temperature ensures that the amount of energy required from the radiation source to liquefy the powdered thermoplastic is minimized. Furthermore, the plastic powder's absorption in the wavelength range of the radiation source is at least twice that of the pure polymer, guaranteeing sufficient liquefaction of the powdered thermoplastic despite the typically lower energy input due to the planar illumination.

[0081] In the process according to the invention, the wavelength of the radiation emitted by the radiation source is preferably matched to the absorber such that at least 70%, preferably at least 80%, and particularly preferably at least 90% of the absorbed radiation is absorbed by the absorber. Preferably, a plastic powder is incorporated into the process as described above.

[0082] In the process, the radiation acting on the plastic powder preferably has a wavelength in the range of 400 nm to 3000 nm, and preferably in the range of (1064 nm and / or (980 nm and / or (940 nm and / or (810 nm and / or (640 nm).) Alternatively, the radiation can have a wavelength in the range of 4800 to 8300 nm (preferably about 5 pm), in which case a plastic powder is used that contains an absorber which absorbs in this wavelength range.

[0083] In the inventive method, exposure is preferably carried out with a radiation source selected from area and / or line exposure units and / or diode arrays and / or laser scanner exposure systems with the option of area exposure by beam shaping. M / EOSG-025-PC

[0084] 15

[0085] The inventive process is further characterized by the fact that the powdered amorphous thermoplastic is applied layer by layer to a carrier system, and in particular is discharged as a powder bed, and is preheated to a temperature in the range of the softening temperature, in particular in the range of Tg-20°C to Tg+20°C, by a heat source before selective solidification. Subsequently, the powdered amorphous thermoplastic is selectively solidified by the action of radiation. The softening temperature of the polymer is determined for the pure polymer by DSC measurement according to ISO 11357-2:2020-03 as the midpoint of the melting point peak in the measurement.

[0086] In a particularly preferred embodiment of the process, the consolidation is carried out by single or multiple exposure, with multiple exposure being particularly preferred.

[0087] For the execution of the described method, it is preferred that the plastic powder has an absorption of at least 10%, more preferably at least 20%, and even more preferably at least 25% at the wavelength of the radiation source (particularly in the NIR range). Alternatively or additionally, it is preferred that the absorption is at most 95%, more preferably at most 90%, and even more preferably at most 85%. The absorption is to be determined, as described above, using a layer formed from the plastic powder (e.g., with a thickness of 40 pm, 50 pm, or 60 pm), as the amount of incident light minus the amount of light remaining after passing through the layer.

[0088] For the process, it is further preferred if the plastic powder has a melt volume flow rate, determined according to ISO 1133, at a test temperature of 100°C (± 10°C) above the glass transition temperature (determined by DSC according to ISO 11357-2) and a test weight of 5 kg of at least 5 cm. 3 / 10 min, preferably at least 8 cm 3 / 10 min, preferably 10 cm 3 / min, especially preferred 15 cm 3 / 10 min and a maximum of 200 cm 3 / 10 min, preferably no more than 150 cm 3 / 10 min, preferably no more than 120 cm 3 / 10min. M / EOSG-025-PC

[0089] 16

[0090] Alternatively or additionally, it is preferred if the plastic powder used in the inventive process exhibits coalescing behavior, i.e., that pronounced sinter necks are formed between the particles and, preferably, a melt film is formed from the adjacent particles when the plastic powder is heated by hot-bed microscopy at a heating rate of 20°C / min to 40°C above processing temperature. It is particularly suitable if the molten material also flows together over longer distances.

[0091] Alternatively or additionally, it is preferred if the plastic powder used in the inventive process has a glass transition temperature Tg, a particle size D50, a sphericity, a BET surface and / or a bulk density as specified above as preferred for the polymer powder according to the invention.

[0092] The inventive method can also be configured such that the polymer powder according to the invention is only produced during processing within the process by first applying a powder layer and subsequently applying absorbers selectively (regioselectively) to areas of this powder layer that are to be solidified, in order to adjust the absorption of the polymer powder in the wavelength range of the radiation source used within the range specified by the method. For this purpose, the absorber can, for example, be formulated as an ink with a carrier solvent, which is evaporated after application to the polymer powder.Since in this case areas with plastic powder according to the invention and areas in which polymer particles without absorber are present are produced, it is not necessary with such a process to selectively irradiate the areas to be solidified, and instead an imager can be used that irradiates the entire layer. In this embodiment, the absorber is therefore selectively applied to the areas to be solidified, and the areas to be solidified are preferably selectively solidified by means of an imager.

[0093] In another embodiment, the plastic powder is used in the context of the inventive process as a mixture of amorphous polymer and absorber, which is applied layer by layer in the process M / EOSG-025-PC

[0094] 17 is applied and areas to be solidified are treated by selective irradiation.

[0095] For the above-mentioned method, it is further preferred that the energy introduced by the radiation and / or the amount of absorber and / or the weight fraction of the absorber in relation to the total weight of the amorphous polymer and the absorber is / are adjusted depending on the desired layer adhesion, detail resolution and surface quality of the object.

[0096] In a further aspect, the present invention relates to a method for producing a plastic powder for use in a method for producing a three-dimensional object by selectively solidifying a plastic powder as a build-up material at the locations corresponding to the cross-section of the three-dimensional object in the respective layer by the action of radiation, comprising:

[0097] (i) Mixing a thermoplastic polymer, wherein the polymer is preferably amorphous, with one or more absorbers, wherein the absorber may be loose in the powder or fixed on / in the surface of at least part of the particles, depending on the mixing conditions,

[0098] (ii) Incorporation of the absorber before and / or during the pulverization of the thermoplastic polymer, by incorporation into the melt or solution of the polymer or by addition during polymerization and production of the powder by precipitation, milling, spraying, co-extrusion and / or fiber spinning and cutting.

[0099] The plastic powder produced by this process is preferably a plastic powder for use in a process for producing a three-dimensional object, as described above. Alternatively or additionally, it is preferred that, within the scope of the process, the amorphous polymer or the polymer-based particles and / or the absorber are of the type specified above as preferred for the plastic powder according to the invention.

[0100] If the plastic powder according to the invention is produced only by mixing the plastic particles and the particles of the absorber, the M / EOSG-025-PC exhibit

[0101] 18

[0102] The particles should already be the size they are intended to be in the finished plastic powder. In this case, mixing can be carried out without the addition of solvent to produce a dry blend.

[0103] Alternatively, the absorber particles can be applied to the plastic particles, for example, by spraying a dispersion of the NIR radiation absorbing material particles in a solvent onto the plastic particles and then evaporating the solvent, or by producing a mixed dispersion of NIR radiation absorbing material particles, plastic particles, and solvent, and then evaporating the solvent. Incorporation to produce mixed particles can be achieved, for example, by compounding larger plastic particles, such as conventional granules, with NIR radiation absorbing material particles in an extruder and processing them into smaller particles, for example, by generating spun fibers and subsequently cutting them into particles, or by cryogenic milling and, if necessary, subsequent rounding of the particles using a suitable method.

[0104] In a further aspect, the present invention relates to a three-dimensional object produced by selectively solidifying a plastic powder, as described above, as a build-up material at the locations corresponding to the cross-section of the three-dimensional object in the respective layer by the action of radiation. For the production of such three-dimensional objects, reference can be made to the descriptions of methods for producing such objects. Compared to conventionally manufactured three-dimensional objects based on amorphous polymers, such an object is characterized by a significantly lower porosity, preferably exhibiting a density of > 85%, more preferably > 90%, and even more preferably > 95% of the theoretical density of a compact component produced from the plastic powder.The “theoretical density” is calculated from the proportion of all components in the plastic powder and their corresponding densities according to the formula (AnteÜAin% x DensityA + proportion). B in % x density B + ...). M / EOSG-025-PC

[0105] 19

[0106] In a further aspect, the present invention relates to a system for producing shaped bodies by selectively solidifying a powdered build-up material at the locations corresponding to the cross-section of the shaped body in the respective layer by the action of radiation, wherein the system comprises at least one radiation source, a process chamber designed as an open container with 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, a storage container and a coater movable in a horizontal direction, wherein the storage container is at least partially filled with a plastic powder as described above, wherein the system preferably includes at least one radiation source selected from point, line and area exposure units.

[0107] Such a system is described by way of example in Figure 1:

[0108] Figure 1 schematically shows a laser sintering device with a laser beam and a deflection mirror, as is common when using a CCL laser, with which a method for the layer-by-layer fabrication of a three-dimensional object can be carried out. This device has a container 1, which is open at the top and bounded at the bottom by a support 4 for carrying an object 3 to be formed. A working plane 6 is defined by the upper edge 2 of the container (or its side walls). The object is located on the top of the support 4 and is formed from a plurality of layers extending parallel to the top of the support 4, made of a powdered build-up material that can be solidified by means of electromagnetic radiation. In the invention described here, the solidifiable powdered build-up material is the plastic powder according to the invention. The support is adjustable in the vertical direction, i.e.,The support 4 can be moved parallel to the side wall of the container 1. This allows the position of the support 4 relative to the working plane 6 to be adjusted.

[0109] Above the container 1 or the working level 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 M / EOSG-025-PC is provided above the working level 6.

[0110] The elements 1 to 6, 10, and 11 are arranged within the machine frame 100. These elements emit a directed light beam 8. This beam is deflected by a deflecting 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 deflecting device 9. Elements 1 to 6, 10, and 11 are arranged within the machine frame 100.

[0111] 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.

[0112] Suitable process and system parameters are selected for the layer-by-layer melting of the plastic powder according to the invention. In addition to the proportion of absorber to be adjusted, the layer thickness, laser power, and exposure speed are specifically selected.

[0113] In a preferred embodiment of the invention, the electromagnetic radiation is emitted specifically in the NIR range within a window of no more than 50 nm (A2 - A1 < 50 nm), preferably no more than 40 nm, more preferably no more than 30 nm, and particularly no more than 20 nm. This allows the plastic powder according to the invention to comprise other substances that would interfere due to their absorption or reflection properties in a first sub-range of the NIR range. By selecting a relatively narrow wavelength range outside the first sub-range, the interfering influence can be reduced or prevented.

[0114] In a preferred embodiment of the invention, the radiation source emits electromagnetic radiation specifically at one or more wavelengths in the range of 400-3000 nm, in particular at one or more wavelengths in the range of 500 to 1500 nm, more preferably 600 to 1100 nm, and most preferably in one or more of the M / EOSG-025-PC

[0115] 21 subsequent wavelengths: 980±7 nm and / or 940±7 nm and / or 810±7 nm and / or 640±7 nm and / or 1064±7 nm. Preferably, the radiation source emits at 980±7 nm. In an alternative embodiment, the radiation source emits radiation with a wavelength in the range of 4800 to 8300 nm.

[0116] In a preferred embodiment of the invention, the radiation source comprises at least one laser, preferably one or more laser diodes. The laser diodes can be arranged in a cell-like or staggered configuration. It is also possible to arrange the laser diodes in a two-dimensional array. The laser can be an edge emitter. Preferably, it is a surface emitter (VCSEL or Philips VCSEL). High build speeds can be achieved through line exposure. Furthermore, the use of laser diodes enables high efficiency and reduces energy costs.

[0117] Suitable laser diodes typically operate at a power output between 0.1 and 500 watts, preferably at least 1.0 watt and / or at most 100 watts. The laser beam focus can have a radius between 0.05 mm and 1 mm, preferably at least 0.1 mm and / or at most 0.4 mm. The exposure speed, i.e., the speed of the laser focus relative to the build plane, is typically between 10 mm / s and 10,000 mm / s, preferably at least 300 mm / s and / or at most 5,000 mm / s.

[0118] 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".

[0119] The following examples serve for illustration and are not to be understood as limiting. They define further preferred embodiments of the invention. M / EOSG-025-PC

[0120] 22

[0121] Examples:

[0122] Example 1: Sintering test of a mixture of Ultem 1010 and 1040 with mineral

[0123] NIR absorber

[0124] To produce the mixture, 50 wt% Ultem 1010 and 50 wt% Ultem 1040 were compounded with 0.75% of the NIR-absorbing additive Iriotec 8850 (Merck) using a twin-screw extruder. The resulting granules were then spun into filaments with a diameter of approximately 60 µm. Cutting the filaments to a length of approximately 50 µm using a guillotine cutter yielded a powder consisting of cylindrical particles with the additive incorporated. To improve flowability, the free-flowing agent Aerosil 200 (Evonik) was added to the powder after cutting.

[0125] The material was used for build tests on a powder bed-based additive manufacturing system with a diode exposure unit (EOS P500 LPF) and with a volume energy input (total energy over two exposures) in the range of 1.3 to 2.4 J / mm². 3The material is fused into thin plates at a processing temperature of 200°C. A suitable volume energy input, determined using common methods, is in the range of 0.35–0.50 J / mm². 3 The process involved passing the exposure unit over the area to be exposed twice. These plates consist of uniformly and homogeneously fused particles that form a smooth film.

[0126] Example 2: Sintering test of a mixture of Ultem 1010 and 1040 with carbon black

[0127] The powder was produced analogously to Example 1, using 0.1 wt% Mogul L carbon black as an additive, which acts as a broadband absorber in the NIR range. 0.15% Aerosil 200 was added as a flow agent.

[0128] Analogous to Example 1, the obtained powder was processed on an EOS P500 LPF system, where the specified energy input range (total energy) of 0.67 J / mm² 3and at a processing temperature of 200°C, platelets made of homogeneously and uniformly fused particles could also be obtained here. In the M / EOSG-025-PC

[0129] 23

[0130] In this experiment, the area to be exposed was exposed twice by the exposure unit.

[0131] Example 3: Sintering test of a mixture of Ultem 1040 with carbon black

[0132] A polymer powder containing carbon black as a NIR absorber was produced by precipitation from an emulsion: 20 wt% Ultem 1040 was dissolved in a non-water-soluble, low-boiling organic solvent, e.g., methylene chloride, at room temperature and atmospheric pressure. Additionally, 1.0% carbon black Mogul L was added to the polymer solution as an NIR absorber. The polymer solution was dispersed with stirring in a dilute aqueous solution of an emulsion stabilizer, e.g., polyvinyl alcohol Poval 8-88 (volume ratio of polymer solution to aqueous emulsifier solution 1:1 to 1:3), resulting in a homogeneous emulsion. The droplet size, and thus the resulting particle size, can be controlled by selecting the stirring tools and speed. Subsequently, the low-boiling organic solvent was slowly distilled off by increasing the temperature, leaving the polymer-absorber composite as solid particles in the aqueous solution.The solid fraction was isolated by filtration, and the emulsifier was removed by washing with warm water. The resulting powder was dried under vacuum at an elevated temperature, e.g., 60°C, and subjected to protective sieving at 250 pm before further processing to remove any oversize particles. Aerosil R812 was added to improve the powder's flowability.

[0133] The resulting powder was processed on a powder bed-based additive manufacturing test system at a process chamber temperature of 200°C using a laser diode array. The material was processed with volume energy inputs of 0.33 to 0.89 J / mm³. 3 exposed, whereby the energy dose was distributed across two passes of the laser diode array, while the total exposure time of the layer was 300 cm². 2less than 15 seconds. Homogeneously fused platelets were obtained, exhibiting a very smooth, uniform surface and minimal film porosity. When processing the material with a conventional laser scanner system (single M / EOSG-025-PC)

[0134] 24

[0135] With a beam source, a stable, pore-free film cannot be generated with a comparably short exposure time.

[0136] Example 4: Sintering test of a mixture of Ultem 1010 with Fabulase

[0137] A polymer powder containing a NIR absorber was produced by precipitation from an emulsion: 20 wt% Ultem 1010 was dissolved in a non-water-soluble, low-boiling organic solvent, e.g., methylene chloride, at room temperature and atmospheric pressure. Additionally, 5% Fabulase 322 (Chem. Fabrik Budenheim) was added to the polymer solution as an NIR absorber. The polymer solution was dispersed, with stirring, in a dilute aqueous solution of an emulsion stabilizer, e.g., polyvinyl alcohol Poval 8-88 (volume ratio of polymer solution to aqueous emulsifier solution 1:1 to 1:3), so that a homogeneous emulsion was formed. The droplet size, and thus the resulting particle size, can be controlled by selecting the stirring tools and speed. The low-boiling organic solvent was then slowly distilled off by increasing the temperature, so that the polymer-absorber composite was present as a solid particle in the aqueous solution.The solid fraction was isolated by filtration, and the emulsifier was removed by washing with warm water. The resulting powder was dried under vacuum at an elevated temperature, e.g., 60°C, and subjected to protective sieving at 250 pm before further processing to remove any oversize particles. Aerosil R812 was added to improve the powder's flowability.

[0138] The resulting powder was processed on a powder bed-based additive manufacturing test system at a process chamber temperature of 200°C using a laser diode array. The material was treated with volume energy inputs of 0.60 to 1.4 J / mm³. 3 exposed, whereby the energy dose was distributed across two passes of the laser diode array, while the total exposure time of the layer was 300 cm². 2less than 15 seconds. Homogeneously fused platelets were obtained, exhibiting a very smooth, uniform surface and minimal film porosity. When processing the material with a conventional laser scanner system (single M / EOSG-025-PC)

[0139] 25

[0140] With a beam source, a stable, pore-free film cannot be generated with a comparably short exposure time.

[0141] 5: Sintering test of a mixture of Ultem 1010 with carbon black

[0142] The powder was produced analogously to Examples 3 and 4, except that the absorber was not added to the polymer solution, but rather mixed dry with the powder after drying and sieving (dry blend). 1.0% of the carbon black Mogul L was added as a NIR absorber.

[0143] The resulting powder was processed on a powder bed-based additive manufacturing test system at a process chamber temperature of 200°C using a laser diode array. The material was treated with volume energy inputs of 0.44 to 1.1 J / mm³. 3 exposed, whereby the energy dose was distributed across four passes of the laser diode array, while the total exposure time of the layer was 300 cm². 2 The exposure time was less than 15 seconds. Homogeneously fused platelets were obtained, exhibiting a very smooth, uniform surface and minimal film porosity. When processing the material with a conventional laser scanner system (single beam source), a stable, pore-free film cannot be generated with a comparably short exposure time.

[0144] Example 6: Sintering test of a mixture of ABS and carbon black

[0145] A commercially available ABS granulate (Terluran GP-35, Ineos Styrolution) was cryogenically milled into a fine powder on a REKORD 224A pin mill. For this purpose, the granulate was embrittled in liquid nitrogen and fed into the mill. The mill outlet temperature was approximately -20°C. The resulting powder was sieved at a mesh size of 250 µm, and the sieve was used for further processing. 0.1% carbon black (Monarch 570 type) was added to the powder by high-shear mixing on a MIXACO LAB CM 6-12 MB / SM laboratory mixer, reaching a maximum mixing temperature of 80°C. M / EOSG-025-PC

[0146] 26

[0147] The resulting powder was processed on a powder bed-based additive manufacturing test system using a diode array with a wavelength of approximately 980 nm, with the powder bed preheated to 110°C. Sintered platelets were obtained by simple exposure to light.

[0148] Example 7: Sintering test of polystyrene with carbon black

[0149] For these experiments, a commercially available laser sintering powder (PrimeCast 101, EOS) was processed on a powder bed-based additive manufacturing test system at room temperature using a laser diode array. The material was sintered with volume energy inputs ranging from 1.1 to 2.65 J / mm³. 3 The plates were exposed, with the energy dose being distributed across three passes of the laser diode array. Well-fused and straight plates were obtained.

[0150] 8: Sintering test of Ultem 1000 with and without carbon black (not invented)

[0151] Ultem was used to produce the mixture. tm1000 were pulverized by precipitation analogously to Examples 2 to 4, with no carbon black, or 0.1 wt%, 0.5 wt% and 1.0 wt% carbon black of type Mogul L added to the polymer solution. Analogous to Examples 2 to 4, these mixtures were also tested with volume energy inputs between 0.74 and >4 J / mm³. 3 exposed, with the energy input being recorded over up to 20 exposure passes.

[0152] Exposure tests showed that in the sample with 0.1 wt% carbon black, sintered particles were observed after 5 exposure passes, but no film formation had yet occurred. A comparable result was achieved in the sample with 0.5 wt% carbon black after only 2 exposure passes. In the sample with 1.0 wt% carbon black, sintered but not yet fully dispersed particles were observed after a single exposure pass. In the overlap of the cascades, these particles had already dispersed more extensively, and dark streaks were visible. These investigations also revealed a roughly constant depth of penetration, which varied depending on the concentration at comparable energy inputs of M / EOSG-025-PC.

[0153] 27 was independent. A sample without additionally added soot could not be sintered at all.

Claims

M / EOSG-025-PC 28 Claims 1. Method for producing three-dimensional objects from powdered amorphous thermoplastics in powder bed-based additive manufacturing, wherein - the powdered amorphous thermoplastic is applied layer by layer to a carrier system, - the powdered amorphous thermoplastic is preheated to a processing temperature in the range of the softening temperature, in particular in the range Tg-20°C to Tg+20°C, by a heat source, - the powdered amorphous thermoplastic is solidified by a radiation source at the corresponding points in the cross-section of the three-dimensional object in the respective layer, - the radiation source allows for area-wide illumination, and - the plastic powder has an absorption of at least 2 times that of the pure polymer, preferably at least 3 times, particularly preferably at least 5 times that of the pure polymer in the range of the wavelength of the radiation source used.

2. Method according to claim 1, wherein the radiation source is selected from area and / or line exposure units and / or diode arrays and / or laser scanner exposure systems with the option of area exposure by beam shaping, and wherein the incident radiation has a wavelength in the range of 400 nm to 3000 nm, and / or in the range of 4800 to 8300 nm, preferably (1064 nm and / or (980 nm and / or (940 nm and / or (840 nm and / or (810 nm and / or (640 nm).

3. Method according to claim 1 or 2, wherein the plastic powder - exhibits an absorption at the wavelength of the radiation source in the NIR range of at least 10%, preferably at least 20%, particularly preferably at least 25% and / or of at most 95%, preferably at most 90%, particularly preferably at most 85%. - and a melt volume flow rate of the plastic powder, determined according to ISO 1133, at a test temperature of 100°C (1 10°C) above the M / EOSG-025-PC 29 Glass transition temperature (determined by DSC according to ISO 11357-2) and a test weight of 5 kg at least 5 cm 3 / 10 min, preferably at least 8 cm 3 / 10 min, preferably 10 cm 3 / min, especially preferred 15 cm 3 / 10 min and a maximum of 200 cm 3 / 10 min, preferably no more than 150 cm 3 / 10 min, preferably no more than 120 cm 3 / 10min, and preferably also has one or more of the following properties: - Coalescence behavior; - and / or a (maximum) glass transition temperature Tg, measured by DSC, of ​​about 50 to 300 °C and preferably of at least 80 and / or at most 250 °C - a particle size D50, determined by laser diffraction, of at least 20 pm, preferably at least 30 pm, more preferably at least 40 pm, and / or a maximum of 150 pm, preferably a maximum of 100 pm and more preferably a maximum of 80 pm; - a sphericity greater than 0.6, preferably greater than 0.7, even more preferably greater than 0.8, particularly preferably greater than 0.9; - a BET surface, determined according to DIN ISO 9277, of less than 20 m² 2 / g, preferably less than 10 m 2 / g, preferably less than 5 m 2 / g and even more preferably less than 2 m 2 / g; a bulk density according to DIN EN ISO 60 of at least 0.35 g / cm³ 3 , preferably at least 0.4 g / cm³ 3 , particularly preferably at least 0.45 g / cm² 3and / or a maximum of 0.7 g / cm² 3 , preferably a maximum of 0.65 g / cm².

4. Method according to one of the preceding claims, wherein the selective solidification is carried out by single or multiple exposure and preferably by multiple exposure.

5. Method according to one of the preceding claims, wherein an absorber is applied regioselectively to the areas of the plastic powder to be solidified during layer-by-layer processing in order to adjust the absorption of the plastic powder in the range of the wavelength of the radiation source used to the range specified by claim 1. M / EOSG-025-PC 30 6. Plastic powder for use in a process according to one of claims 1-5, wherein the plastic of the plastic powder is formed from an amorphous polymer and the plastic powder has an added absorber, which is preferably incorporated into powder particles and / or is present on their surface.

7. Plastic powder according to claim 6, wherein the absorber is selected from the group consisting of carbon black, graphite, salts, metals and metal oxides, carbon fibers, as well as organic and inorganic color pigments, copper phosphate or copper hydroxyphosphate, chalk, and mica pigments.

8. Plastic powder according to claim 6 or 7, wherein the weight fraction of the absorber, based on the total weight of amorphous polymer and absorber, is at least 0.01 wt.%, preferably at least 0.05 wt.%, more preferably at least 0.1 wt.%; and / or wherein the weight fraction of the absorber in the total weight of the amorphous polymer and the absorber is at most 10 wt.%, preferably at most 5 wt.%, more preferably at most 2 wt.%, wherein the absorber is most preferably in the form of carbon black; and / or wherein the plastic powder contains the absorber in a proportion, based on the total weight of amorphous polymer and absorber, such that the ratio of absorption of the incident radiation by the absorber to absorption of the incident radiation by the amorphous polymer is at least 2, preferably at least 5, more preferably at least 10.

9. Plastic powder according to at least one of claims 6 to 8, wherein the plastic powder is substantially free of crystalline or semi-crystalline polymers and / or wherein the plastic powder is free of reactive components.

10. Plastic powder according to at least one of claims 6 to 9, wherein the amorphous polymer is selected from the group consisting of at least one polyetherimide, polyaryletherketone (PAEK), polyethersulfone M / EOSG-025-PC 31 (PES), polyphenylene sulfone (PPSU), polysulfone (PSU), polyamide, polyester, polyether, polylactide, polyolefin, polystyrene, polyphenylene oxide, polyimide, polycarbonate, polyvinyl chloride, acrylonitrile butadiene styrene (ABS), styrene acrylonitrile (SAN), polyacrylate, polymethacrylate, polyamide-imide, polyurethane, or mixtures of these polymers, and / or wherein the amorphous polymer is selected from the group consisting of at least one copolymer comprising at least one monomer unit of one of the preceding polymers, and / or at least one polymer blend comprising at least one of the aforementioned polymers or copolymers.

11. Plastic powder according to at least one of claims 6 to 10, wherein the plastic powder additionally contains one or more additives, which are preferably selected from the group comprising fibers, in particular organic fibers, glass fibers, wollastonite, carbon fibers, carbon nanotubes, glass beads, pigments, in particular in the form of calcium carbonate or titanium dioxide, flame retardants, UV stabilizers, and heat stabilizers.

12. A method for producing a plastic powder for use in a method for producing a three-dimensional object by selectively solidifying a plastic powder as a build-up material at the locations corresponding to the cross-section of the three-dimensional object in the respective layer by the action of radiation, preferably for use in a method according to one of claims 1 to 5, comprising: (i) Mixing a thermoplastic polymer powder with one or more absorbers, wherein the absorber may be loose in the powder or fixed to / in the surface of at least part of the particles, depending on the mixing conditions, (ii) Incorporation of the absorber before and / or during the pulverization of the thermoplastic polymer, by incorporation into the melt or solution of the polymer or by addition during polymerization and production of the powder by precipitation, milling, spraying, co-extrusion and / or fiber spinning and cutting. M / EOSG-025-PC 32 13. Three-dimensional object which can be produced or has been produced by selectively solidifying a plastic powder according to one of claims 6 to 11 as a building material at the locations corresponding to the cross-section of the three-dimensional object in the respective layer by the action of radiation.

14. Three-dimensional object according to claim 13, wherein the polymer matrix of the three-dimensional object is substantially amorphous and / or the object has a density of >85%, preferably > 90% and further preferably > 95% of the theoretical density of a compact object produced from the plastic powder.

15. System for producing shaped bodies by selectively solidifying a powdered build-up material at the locations corresponding to the cross-section of the shaped body in the respective layer by the action of radiation, wherein the system comprises at least one radiation source, a process chamber designed as an open container with 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, a storage container and a coater movable in a horizontal direction, wherein the storage container is at least partially filled with a plastic powder according to one of claims 6 to 11 as build-up material, wherein the system preferably includes at least one radiation source selected from point, line and area exposure units.

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