Method for manufacturing a three-dimensional object

Abstract

The invention relates to a method for manufacturing a three-dimensional object using additive manufacturing, in particular selective laser sintering (L-PBF), said method comprising the steps of: (a) providing a starting material that is solid at 25°C and comprises a thermally curable resin composition and a sintering material, (b) additively manufacturing the three-dimensional object, (c) thermally curing at least part of the resin composition in the three-dimensional object, (d) decomposing the resin composition in the three-dimensional object, and (e) thermally treating the three-dimensional object. The invention also relates to the use of a starting material that is solid at 25°C in additive manufacturing, in particular in selective laser sintering (L-PBF), to manufacture a three-dimensional object, wherein the starting material comprises a thermally curable resin composition and a sintering material, characterised in that the starting material comprises the sintering material in an amount of 20 vol.% or more relative to the total volume of the starting material.

Description

[0001] Method for producing a three-dimensional object

[0002] The present invention relates to a method for producing a three-dimensional object using additive manufacturing, in particular selective laser sintering (L-PBF).

[0003] The invention further relates to the use of a starting material which is solid at 25 °C in additive manufacturing, in particular in selective laser sintering (L-PBF), for producing a three-dimensional object, wherein the starting material comprises a thermosetting resin composition and a sintering material.

[0004] Methods for producing three-dimensional objects using additive manufacturing are known in the prior art. A method for producing three-dimensional plastic objects is described, for example, in DE 10 2019 212 298 A1, wherein a powder mixture is used for selective laser sintering. The powder mixture comprises a first powder with powder particles containing a first thermoplastic polymer material and a reinforcing material, and a second powder with powder particles containing a second thermoplastic polymer material. The reinforcing material can comprise carbon fibers, glass fibers, carbon nanotubes, glass spheres, or a flame retardant, wherein the flame retardant can comprise metal oxides, metal hydroxides, metal II salts, boron and zinc compounds, silicon compounds, graphite, or nitrogen-based melamine-based flame retardants.

[0005] Methods for producing three-dimensional ceramic objects are also known in the prior art, for example from WO 2018 / 005350 A1, where production takes place using a fused filament fabrication (FFF) process. This process uses a mixture consisting of an organic reactive material (e.g., prepolymers of polyurethanes, polyesters, epoxies, silicones) and inorganic particles that is flowable at room temperature. The inorganic particles can comprise a metal or a ceramic, such as an oxide, nitride, or carbide. The amount of inorganic particles in the mixture can range from 10 to 80 wt.%, based on the total weight of the mixture. The mixture is deposited in layers in the form of filaments at room temperature or directly extruded to produce a three-dimensional object. The organic reactive material is then cured at room temperature or at an elevated temperature to obtain a thermoset.The three-dimensional object is then heated to a temperature of 400 °C or more to decompose the thermoset, forming a carbon phase to bind the inorganic particles. The resulting three-dimensional object exhibits a high porosity of at least 35%.

[0006] Photolithographic processes are also used to produce three-dimensional ceramic objects, for example lithography-based ceramic manufacturing (LCM). In this process, a liquid mixture comprising a photopolymer and a ceramic raw material is printed layer by layer. After each layer has been applied, the photopolymer contained therein is polymerized by irradiation with light. After additive manufacturing, the three-dimensional object is heated to remove the binder, and the ceramic particles are then densified by sintering. Although ceramic objects with a comparatively high resolution can be produced using LCM processes, care must be taken to ensure that the light is not scattered or absorbed by the ceramic raw material, as this can impair printability and resolution. LCM processes are also low in productivity and cost-intensive.

[0007] Another established process for producing three-dimensional objects is binder jetting (BJT). In this process, powdered starting material is applied layer by layer and selectively bonded with an organic binder between each application. The resulting bonded powder objects exhibit high porosity, usually over 50 vol%, and only low compressive strength.

[0008] Furthermore, methods for producing three-dimensional ceramic or metallic objects using additive manufacturing are known in the state of the art.

[0009] EP 2998 282 Al relates to a method for producing a reaction-bonded silicon carbide component.

[0010] WO 2018 / 079169 A1 relates to a method for producing modeling material, modeling material, three-dimensional modeling method and three-dimensional modeling system.

[0011] US 2005 / 0191200 Al relates to a method and a composition for the production of metal freeform surfaces.

[0012] WO 2016 / 127521 A1 relates to a method for producing a composite product from short fiber reinforced thermosetting resin by means of 3D printing.

[0013] The quality of three-dimensional, ceramic objects produced by additive manufacturing can hardly be improved by post-processing (e.g. grinding), as this is complex and difficult due to the hardness and brittleness of the ceramic object, and is associated with high tool wear and a risk of breakage of the ceramic object. Furthermore, some surfaces of geometrically complex objects often cannot be post-processed at all due to their inaccessibility, or can only be done by complex flow grinding. There is therefore a need for a method with which three-dimensional, particularly ceramic, objects can be produced with fine, complex structures in different sizes and with high productivity, without the need for post-processing. It is an object of this invention to provide such a method.

[0014] The invention relates to a method for producing a three-dimensional object using additive manufacturing, in particular selective laser sintering (L-PBF), comprising the steps:

[0015] (a) providing a starting material which is solid at 25 °C and comprises a thermosetting resin composition and a sintered material,

[0016] (b) Additive manufacturing of the three-dimensional object,

[0017] (c) at least partially heat-curing the resin composition in the three-dimensional object,

[0018] (d) decomposition of the resin composition in the three-dimensional object, and (e) heat treatment of the three-dimensional object.

[0019] Surprisingly, the process enables the production of three-dimensional, particularly ceramic, objects in a wide variety of sizes, combining a short production time with good precision and high stability of the objects, even after the decomposition of the resin composition.

[0020] The starting material can, for example, comprise a powder, granules, and / or filaments. The shape of the starting material can thus be easily adapted to the respective additive manufacturing process. The invention is not limited to starting materials in the form of powder, granules, and / or filaments. It is preferred if the starting material is in powder form. This makes it particularly suitable for selective laser sintering (Laser Power Bed Fusion, L-PBF).

[0021] In principle, however, any additive manufacturing process can be used for step (b); provided that the process is suitable for processing starting materials that are solid at 25 °C and thus a three-dimensional object can be obtained from the starting material. Such additive manufacturing processes are sufficiently known to the person skilled in the art and are listed, for example, in Wohlers Report 2022: 3D Printing and Additive Manufacturing Global State of the Industry, Wohlers Associates, ISBN 0991333292, 9780991333295. The following additive manufacturing methods are particularly suitable for carrying out step (b): the binder jetting process, the high-speed sintering process, the selective heat sintering process (SHS), the fused deposition modeling process (FDM), and, as already mentioned, the selective laser sintering process (L-PBF).

[0022] The starting material preferably has a d5o particle size of 10 to 100 pm, more preferably 20 to 60 pm, even more preferably 25 to 50 pm, in particular 30 to 40 pm. This can result in a uniform layer structure in additive manufacturing, particularly in powder bed processes such as L-PBF, and a three-dimensional object with a smooth surface can be obtained. The d5o particle sizes specified in this description can be determined according to the ISO 8130-13:2019 standard. For micro-SLS or micro-L-PBF processes, the starting material preferably has a comparatively small d5o particle size of 2 to 10 pm, more preferably 4 to 8 pm. For the binder jetting process, the d5o particle size of the starting material is preferably in the range of 5 to 100 pm, more preferably 15 to 40 pm.If another additive manufacturing process is used, the person skilled in the art, using his or her general technical knowledge, selects a dosage form of the starting material that is suitable for the respective process, such as a suitable particle size for powdered or granular starting materials or a suitable diameter for starting materials in the form of a filament.

[0023] Preferably, the starting material is solid at 30°C, more preferably at 40°C, and even more preferably at 50°C. The chain mobility of molecules in the starting material is comparatively low when stored in the solid state. Consequently, the risk of initiating a curing reaction in the starting material prior to additive manufacturing, especially during storage of the starting material, can be significantly reduced, and the storage stability of the starting material can thus be increased. Likewise, handling a solid starting material can be easier and safer than liquid starting materials.

[0024] The thermosetting resin composition preferably at least partially encloses the sintered material. This can improve the homogeneity of the three-dimensional object because the thermosetting resin composition and the sintered material can then be distributed particularly evenly within the three-dimensional object. Consequently, the shape of the three-dimensional object can be very well retained even after the decomposition of the resin composition. Likewise, this can reduce or even completely prevent separation of the thermosetting resin composition from the sintered material, thereby improving both the printability of the starting material and the recyclability of excess starting material, e.g., from a powder bed or an overflow container of the 3D printer.To provide a starting material in which the thermosetting resin composition at least partially envelops the sintered material, the thermosetting resin composition and the sintered material are preferably coextruded. Alternatively, another melt-mixing process can be used, for example, using a heatable stirred reactor. A spray-drying process is also possible.

[0025] In a preferred embodiment, at least one particle of the sintered material is completely surrounded by the thermosetting resin composition, preferably at least 10% of the particles of the sintered material, more preferably at least 20% of the particles of the sintered material, even more preferably at least 30% of the particles of the sintered material, in particular at least 40% of the particles of the sintered material or even at least 50% of the particles of the sintered material.

[0026] According to a further preferred embodiment, the starting material is obtained in a process which comprises contacting, in particular mixing, the sintered material in the solid state with the thermosetting resin composition in the molten state. This contacting preferably comprises co-extrusion (as disclosed in particular in the preceding paragraph) or mixing the sintered material and resin composition in a heated stirred tank, both preferably in such a way that the resin composition transitions to the molten state during co-extrusion / mixing, while the sintered material remains solid. The resulting extrudate / mixture can then be ground, for example, to obtain the starting material.

[0027] The melting (or softening) of the thermosetting resin composition can be achieved, for example, by heating and / or the application of shear forces. It is understood that a certain maximum temperature (e.g., 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or 140°C), in particular the curing temperature of the thermosetting resin composition (or the lower limit of the corresponding curing temperature range), is not exceeded or is exceeded only temporarily (e.g., for less than 240 seconds, or 120 seconds, or 60 seconds, or less than 30 seconds), so that premature curing of the thermosetting resin composition is completely or at least largely avoided.

[0028] The provided starting material comprises a thermosetting resin composition. The resin composition comprises a thermosetting resin that can react with a hardener contained in the resin composition upon the addition of thermal energy and / or be self-curing. Preferably, the resin is not self-curing, so that the resin composition also comprises a hardener in addition to the resin. The use of a thermosetting resin composition instead of a thermoplastic, non-curable polymer, as known from the prior art, is advantageous because, due to the higher rigidity and higher temperature resistance of a thermoset, which forms during the at least partial heat curing of the resin composition according to the invention, comparatively good dimensional stability of the three-dimensional object can be provided even at a higher temperature.This is particularly advantageous during the decomposition step of the resin composition, as it can improve the dimensional stability of the object.

[0029] The starting material preferably comprises the resin composition in an amount of 10 to 60 wt%, more preferably 20 to 50 wt%, even more preferably 20 to 45 wt%, particularly preferably 25 to 45 wt%, based on the total weight of the starting material, for example 15, 25, 30, 35, or 40 wt%. The resin composition can then stabilize the three-dimensional object well, especially after its at least partial heat curing. Likewise, good printability of the starting material can then be ensured.

[0030] The thermosetting resin composition preferably has a curing temperature of 80°C or more, more preferably in the range of 100 to 250°C, even more preferably 150 to 250°C, and particularly preferably 160 to 220°C. This prevents accidental curing of the resin composition, e.g., during production, storage, or transportation of the resin composition, or during additive manufacturing, particularly if this occurs without partial heat curing of the resin composition. At the same time, at least partial heat curing of the resin composition can occur rapidly as soon as the resin composition is heated to a temperature equal to or higher than the curing temperature.

[0031] The thermosetting resin composition preferably comprises an epoxy resin and / or a polyester resin. The polyester resin can improve the processing properties of the starting material, while the epoxy resin can impart good stability to the three-dimensional object even before at least partial thermosetting.

[0032] The weight ratio of polyester resin to epoxy resin is preferably in the range of 2.0:1.0 to 1.0:4.0 (polyester:epoxy resin), more preferably from 1.0:1.0 to 1.0:2.0, even more preferably from 1.0:1.0 to 1.0:1.7, and particularly preferably from 1.0:1.1 to 1.0:1.4. This allows a good balance between processing properties and mechanical properties of the three-dimensional object before and during decomposition of the resin composition. The average functionality of the resin, in particular of the epoxy resin and / or the polyester resin, is preferably two or more, more preferably in the range of two to four, especially preferably two to three. If the resin composition comprises two or more resins, the functionality of all resins is preferably within the stated range. Efficient curing is then possible, and an optimal crosslinking density can be achieved.

[0033] The starting material preferably comprises the polyester resin in an amount of 3 to 30 wt%, more preferably 5 to 30 wt%, even more preferably 10 to 25 wt%, particularly preferably 8 to 20 wt%, based on the total weight of the starting material, for example 12, 14, 16, or 18 wt%. This can result in good processing properties of the starting material, particularly during additive manufacturing in step (b).

[0034] The polyester resin, in particular an amorphous polyester resin, preferably has a glass transition temperature in the range of 50 to 100°C, more preferably 50 to 80°C. If the additive manufacturing and / or the at least partial heat curing of the resin composition takes place above the glass transition temperature of the polyester resin, the polyester resin can be in the entropically elastic state in step (b) and / or in step (c), which can increase its chain mobility and thereby facilitate the processability of the starting material or the curing reaction of the resin composition. Since the polyester resin can be tacky in the entropically elastic state, the cohesion of the layers printed during additive manufacturing can be improved in step (b), even if heat curing does not yet occur.However, the glass transition temperature of the amorphous domains of semi-crystalline polyester resins can also be significantly below the ranges mentioned in this paragraph, for example below 25 °C or even below 0 °C; this is not problematic, however, since the mobility of polymer chains in amorphous domains is limited by the rigidity of the crystalline domains below their melting range, which is usually 80 °C or above, more preferably 100 °C or above.

[0035] The polyester resin preferably comprises an aliphatic polyester resin. This can increase the chain mobility of the polyester resin and, accordingly, the flowability of the starting material at a certain temperature, which can further improve the processability of the starting material.

[0036] The polyester resin preferably comprises a carboxylated and / or hydroxylated polyester resin. The polyester resin can then cure via carboxyl groups and / or hydroxyl groups upon application of thermal energy. The same hardener can then be used to cure the epoxy resin via the epoxy groups and to cure the polyester resin via the carboxyl groups and / or hydroxyl groups. A reaction between the epoxy resin and the polyester resin can also occur, in particular a reaction between the epoxy groups of the epoxy resin and the carboxyl groups of the polyester resin, which can further improve the stability and homogeneity of the resulting three-dimensional network (i.e., the thermoset).The carboxylated polyester resin preferably has an acid number in the range of 10 to 100 mg KOH / g, preferably 20 to 90 mg KOH / g, more preferably 20 to 50 mg KOH / g, even more preferably 25 to 40 mg KOH / g, for example, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85 mg KOH / g. The carboxylated polyester resin may also have an acid number in the range of 30 to 90 mg KOH / g, preferably 50 to 90 mg KOH / g, more preferably 60 to 85 mg KOH / g. The hydroxylated polyester resin preferably has a hydroxyl number in the range of 10 to 300 mg KOH / g, more preferably 15 to 200 mg KOH / g, even more preferably 20 to 100 mg KOH / g, for example, 30, 40, 50, 60, 70, 80, or 90 mg KOH / g. Likewise, a carboxyl / hydroxyl bifunctional polyester resin can be used, which is understood to mean a polyester resin whose acid number and hydroxyl number are each 10 mg KOH / g or higher, preferably 15 mg KOH / g or higher.This can result in a crosslinking density through which an optimal ratio of the mechanical properties of the resin composition can be obtained, in particular an optimal ratio between elongation at break and stress at break.

[0037] The polyester resin preferably comprises a semi-crystalline polyester resin. At the melting temperature of the semi-crystalline polyester resin, crystalline domains can melt, which can significantly reduce the viscosity of the starting material. If the processing, in particular additive manufacturing, takes place at a temperature close to or above the melting temperature of the semi-crystalline polyester resin, the processability of the starting material can be significantly improved. Preferably, step (b) is carried out at a temperature in the range of 50°C below and 20°C above the melting temperature, more preferably in the range of 40°C below and 10°C above the melting temperature. In a powder bed process, for example L-PBF, the temperature during additive manufacturing in step (b) is understood to mean the powder bed temperature.Semi-crystalline polymers do not have a sharp melting peak, but rather a melting range, and crystalline domains can begin to melt even below the melting temperature. The viscosity can therefore be reduced even if the additive manufacturing takes place in the temperature range mentioned below the melting temperature of the semi-crystalline polyester resin. Due to the viscosity reduction and the associated improved chain mobility, the rate of the curing reaction of the resin composition during heat curing can also increase, whereby the three-dimensional object can be stabilized as quickly as possible by the forming three-dimensional network of the resin composition, thus ensuring good dimensional stability. In a powder bed process, the temperature during additive manufacturing in step (b) (ieThe powder bed temperature (the powder bed temperature) is below the melting range of the semi-crystalline polyester resin, as this improves the recyclability of excess starting material and the unpacking behavior of the three-dimensional object from the powder bed. However, in an L-PBF process, the brief laser irradiation of the powder bed can, of course, result in a temperature significantly above the powder bed temperature and thus also above the melting range of the semi-crystalline polyester at those points that correspond to a cross-sectional area of ​​the three-dimensional object of the respective layer.

[0038] The melting temperature of the semi-crystalline polyester resin is preferably in the range of 80 to 150 °C, more preferably 90 to 130 °C, even more preferably 90 to 120 °C, particularly preferably 105 to 120 °C. The additive manufacturing in step (b) can then be carried out at a temperature that is above the melting temperature of the semi-crystalline polyester resin and at the same time below a curing temperature of the starting material.

[0039] Preferably, the resin composition comprises a semi-crystalline polyester resin with a melting temperature in the range of 105 to 120 °C and a viscosity at 120 °C of 2.0 Pa s or below. This can significantly improve the processability and curing properties of the starting material.

[0040] The resin composition can comprise a semi-crystalline polyester resin and an amorphous polyester resin. This makes it possible to control the viscosity reduction associated with the melting of crystalline domains of the semi-crystalline polyester resin. The ratio of semi-crystalline polyester resin to amorphous polyester resin is preferably in the range of 3.0:1.0 to 1.0:3.0 (semi-crystalline amorphous), more preferably 2.0:1.0 to 1.0:2.0, even more preferably 1.7:1.0 to 1.0:1.0, and particularly preferably 1.6:1.0 to 1.3:1.0. For example, a higher proportion of the amorphous polyester resin is possible, such as a ratio of 1.0:1.7 (semi-crystalline amorphous); 1.0:1.6; 1.0:1.5; 1.0:1.4; 1.0:1.3; 1.0:1, 2:1, 0:1.1, but also a higher proportion of the semi-crystalline polyester resin is possible, such as a ratio of 1.8:1.0 (semi-crystalline amorphous); 1.7:1.0; 1.6:1.0; 1.5:1.0; 1.4:1.0; 1.3:1.0; 1.2:1.0 or 1.1:1.0.This allows a viscosity reduction advantageous for processing the starting material in additive manufacturing in step (b) to be achieved by melting the crystalline domains (provided the temperature in step (b) is close to or above the melting temperature of the semi-crystalline polyester resin, or, in an L-PBF process, such a temperature is generated at least briefly at the irradiated cross-sectional surfaces of the three-dimensional object). It may also be advantageous to use only semi-crystalline polyester resin, as this allows a particularly high viscosity reduction to be achieved. However, it should be noted that this strong viscosity reaction can also lead to a loss of printing precision in step (b), depending on the geometry of the three-dimensional object and the selected process parameters.If this problem occurs, the addition of an additional amorphous polyester resin has often proven effective.

[0041] The glass transition temperature of the amorphous polyester resin is preferably in the range of 35 to 70°C, more preferably 45 to 65°C, and even more preferably 50 to 65°C. If the additive manufacturing and / or the at least partial heat curing of the resin composition takes place above the glass transition temperature of the amorphous polyester resin, the amorphous polyester resin can be in an entropically elastic state, which increases its chain mobility and can thereby facilitate the processability of the starting material or the curing reaction of the resin composition. Likewise, a glass transition temperature in this range has a beneficial effect on the storage and transport stability of the starting material.Possible commercially available polyester resins that can be used alone or in combination are Uralac P5127 (Covestro, Germany; Tg of 57°C, acid number of 69-79 mg KOH / g, viscosity at 150°C of 18-38 Pa s); Uralac P3250 (Covestro, Germany; Tg of 53°C, acid number of 70-85 mg KOH / g, viscosity at 160°C of 7-17 Pa s); Crylcoat 1510-0 (Allnex, Germany; Tg of 58°C, acid number of 71 mg KOH / g, viscosity at 175°C of 8.5 Pa s); Crylcoat 1573 (Allnex, Germany; Tg of 56°C, acid number of 70 mg KOH / g, viscosity at 200°C of 3.5 Pa s); Sirales PE8210 (SIR Industrial, Italy; Tg of 56 °C, acid number of 68-78 mg KOH / g, viscosity at 200 °C of 1.2-4.0 Pa s); Sirales PE5900 (SIR Industrial, Italy; Tg below 0 °C; melting range of 105-120 °C, acid number of 28-36 mg KOH / g, viscosity at 120 °C of 1.5 Pa s; semi-crystalline, carboxylated polyester resin).

[0042] The starting material preferably comprises the epoxy resin in an amount of 5 to 35 wt%, more preferably 10 to 30 wt%, even more preferably 15 to 28 wt%, and particularly preferably 15 to 25 wt%, based on the total weight of the starting material, for example 18, 22, 24, or 26 wt%. The three-dimensional object can then exhibit good mechanical properties immediately after its additive manufacturing, in particular high tensile and compressive strength. Shrinkage resulting from the at least partial heat curing of the resin composition can also be reduced by adding the epoxy resin in the stated amount.

[0043] The epoxy resin preferably has a glass transition temperature in the range of 60 to 150°C, more preferably 80 to 120°C. If the additive manufacturing and / or the at least partial heat curing of the resin composition takes place above the glass transition temperature of the epoxy resin, the epoxy resin can be in the entropically elastic state, which can increase its chain mobility and thereby facilitate the processability of the starting material or the curing reaction of the resin composition. Since the epoxy resin can be sticky in the entropically elastic state, the cohesion of the layers printed during additive manufacturing can be improved in step (b), even if heat curing does not yet occur. Likewise, a glass transition temperature in this range has a beneficial effect on the storage and transport stability of the starting material. Again, in the L-PBF process, the temperature of step (b) (ieThe temperature of the powder bed (e.g. the powder bed temperature) can also be selected below the glass transition temperature of the epoxy resin, and only upon irradiation by the laser and the associated short-term temperature increase on the irradiated cross-sectional areas of the three-dimensional object can the epoxy resin then be in the entropy-elastic state, which results in the advantages described.

[0044] The epoxy resin preferably has a viscosity at 150 °C in the range of 0.1 to 10 Pas, more preferably 0.5 to 10 Pas, even more preferably 1.0 to 5.0 Pas. This can improve the flowability of the starting material and consequently the processability in additive manufacturing.

[0045] The epoxy equivalent weight (EEW) of the epoxy resin is preferably 150 g / eq or more, more preferably 350 g / eq or more, even more preferably in the range of 350 to 1000 g / eq, particularly preferably in the range of 350 to 700 g / eq; for example, 400, 450, 500, 550, 600, or 650 g / eq. This can result in a good balance between the elongation at break and the stress at break of the three-dimensional object before the decomposition of the resin composition, especially after at least partial heat curing of the resin composition.

[0046] The epoxy resin preferably comprises an aromatic epoxy resin, in particular an aromatic epoxy resin selected from the group comprising a bisphenol-based epoxy resin, a novolak-based epoxy resin, a phenol-based epoxy resin, and a naphthalene-based epoxy resin, or a mixture thereof, wherein the bisphenol-based epoxy resin preferably comprises a bisphenol A-based epoxy resin. These epoxy resins are rapidly curable, provide good mechanical properties, and are readily miscible with polyester resins.

[0047] The resin composition preferably comprises one or more epoxy resins, wherein the epoxy resin or at least one of the epoxy resins has an epoxy equivalent weight of 350 to 600 g / eq, more preferably 400 to 500 g / eq, and a viscosity at 150°C of 10.0 Pa s or less, preferably all epoxy resins. This not only provides particularly good processability of the starting material, but also good stability, especially good tensile and compressive strength, of the three-dimensional object before decomposition of the resin composition, especially after at least partial heat curing.

[0048] Possible commercially available epoxy resins that can be used alone or in combination are Kukdo KD-213 (Kukdo Chemical, South Korea; Tg of 88-98 °C, EEW of 730-840 g / eq, viscosity at 150 °C of 3.5-7.0 Pa s); Kukdo KD-2011 (Kukdo Chemical; Tg of 90-100 °C, EEW of 400-500 g / eq, viscosity at 150 °C of 1.0-3.5 Pa s); DER 6225 HT (Olin Corporation, US; Tg of 87-95 °C, EEW of 650-725 g / eq, viscosity at 150 °C of 0.8-1.6 Pa s); DER 642U-20 (Dow Chemical Company; Tg of 89-97 °C, EEW of 500-560 g / eq, viscosity at 150 °C of 1.9-3.3 Pa s); DER 6510-HT (Olin Corporation, US; EEW of 410-440 g / eq, viscosity at 150 °C of 7.5-9.5 Pa s; novolak-modified epoxy resin); DER 671 (Olin Corporation, US; Tg of 75-85 °C, EEW of 475-550 g / eq, viscosity at 150 °C of 0.4-0.95 Pa s); DER692 (Olin Corporation, US; Tg of 89-97 °C, EEW of 660-720 g / eq, viscosity at 150 °C of 1.6-2.4 Pa s); Araldite GT6064 (Huntsman, US; Tg of 82-90 °C, EEW of 600-700 g / eq, viscosity at 150 °C of 0.6-1.5 Pa s); Araldite GT7220 (Huntsman, US; Tg of 95 °C, EEW of 520-545 g / eq, viscosity at 175 °C of 1-2 Pa s); Epon 165 (Westlake Epoxy, US; melting range of 90-100 °C, EEW of 200-230 g / eq, viscosity at 150 °C of 3-5 Pa s); Epiclon 152 (DIC Corporation, Japan; Tg of 56-66 °C, EEW of 340-380 g / eq, viscosity at 150 °C of 1.0 Pa s); Epiclon HP-4710 (DIC Corporation, Japan; Tg of 95-96 °C; EEW of 160-171 g / eq; viscosity at 150 °C of 1 Pa s).

[0049] The resin composition preferably comprises an elastomer-modified epoxy resin. This can improve the impact strength of the three-dimensional object and reduce its brittleness. Preferably, the resin composition comprises the elastomer-modified epoxy resin in addition to another resin, preferably in addition to an epoxy resin (i.e., a non-elastomer-modified epoxy resin) and / or a polyester resin, more preferably in addition to a non-elastomer-modified epoxy resin and / or a carboxylated polyester resin. A particularly good balance between the impact strength and stiffness properties of the three-dimensional object can then be achieved.

[0050] The starting material preferably comprises the elastomer-modified epoxy resin in an amount of 1 wt% or more, more preferably 5 wt% or more, even more preferably 1 to 10 wt%, most preferably 5 to 10 wt%, based on the total weight of the starting material. Preferably, the starting material comprises the elastomer-modified epoxy resin in addition to another, non-elastomer-modified epoxy resin in an amount of 1 to 50 wt%, more preferably 5 to 50 wt%, even more preferably 20 to 50 wt%, even more preferably 30 to 40 wt%, based on the total weight of epoxy resin in the starting material. This allows the impact strength of the three-dimensional object to be significantly improved without significantly reducing its stability, in particular its rigidity.

[0051] The epoxy equivalent weight of the elastomer-modified epoxy resin is preferably 600 g / eq or more, preferably 800 g / eq or more, more preferably 900 g / eq or more, even more preferably in the range of 900 to 1500 g / eq, particularly preferably in the range of 1200 to 1500 g / eq. The elastomer-modified epoxy resin can then be readily incorporated into the three-dimensional network formed during at least partial heat curing.

[0052] The glass transition temperature of the elastomer-modified epoxy resin is preferably 60°C or higher, more preferably 80°C or higher, even more preferably in the range of 80 to 150°C, even more preferably 85 to 120°C. During additive manufacturing of the three-dimensional object, the glass transition temperature can then be exceeded, which can improve the processability of the starting material. In an L-PBF process, this can also only occur upon laser irradiation.

[0053] The average functionality of the elastomer-modified epoxy resin is preferably two or more, more preferably three or more. The epoxy resin can then cure efficiently, and an optimal crosslink density can develop. The average functionality is related to the number of functional groups in the epoxy resin (i.e., not to functional groups in the elastomer, if present).

[0054] The elastomer-modified epoxy resin preferably has an elastomer content of 20 to 60 wt%, more preferably 20 to 50 wt%, and even more preferably 25 to 40 wt%, based on the weight of the elastomer-modified epoxy resin. This allows the balance between impact strength and stiffness to be well adjusted.

[0055] The elastomer-modified epoxy resin preferably comprises a polyacrylate rubber (ACM), an acrylonitrile-butadiene rubber (NBR), and / or a hydrogenated acrylonitrile-butadiene rubber (HNBR), particularly preferably a carboxylated NBR and / or HNBR, in particular a carboxyl-terminated acrylonitrile-butadiene rubber (CTBN). The functional groups of the rubber can, if desired, react with a suitable hardener to form a three-dimensional network, which can further improve the impact strength of the three-dimensional object. The use of a carboxylated rubber has the advantage that no separate hardener is required for its crosslinking, but that the hardener used for curing the resin, in particular the epoxy resin and / or the polyester resin, can also be used for crosslinking the rubber. The carboxyl groups of the rubber can, if desired,react with functional groups of the resin, in particular with epoxy groups of the epoxy resin, and / or with carboxyl groups and / or hydroxyl groups of the carboxylated and / or hydroxylated polyester resin during at least partial heat curing and thus further improve the stability of the three-dimensional object.

[0056] Possible commercially available elastomer-modified epoxy resins that can be used alone or in combination are Hypox RK84L (Huntsman, US; Tg of 100 °C, EEW of 1250-1500 g / eq); HyPox RK820 (Huntsman, US; Tg of 75-95 °C, EEW of 850-1050 g / eq); DER858 (Olin Corporation, US; Tg of 95-105 °C, EEW of 380-420 g / eq); FORTEGRA 104 (Olin Corporation; EEW of 960-1060 g / eq); FORTEGRA 304 (Olin Corporation; Tg of 105-115 °C, EEW of 920-1090 g / eq); KSR-1000 (Kukdo Chemical, Korea; EEW of 1100-1300 g / eq, silicone-modified epoxy resin); KR-102 (Kukdo Chemical, Korea; EEW of 1100-1300 g / eq, CTBN-modified epoxy resin); KR-101 (Kukdo Chemical, Korea; CTBN-modified epoxy resin); KR-104L (Kukdo Chemical, Korea; EEW of 1100-1300 g / eq, CTBN-modified epoxy resin); KR-692 (Kukdo Chemical, Korea, EEW of 675-775 g / eq, acrylic elastomer-modified epoxy resin); KR-693 (Kukdo Chemical, Korea, EEW of 800-900 g / eq, acrylic elastomer-modified epoxy resin); Struktol Polydis 3610 (Schill+Seilacher "Struktol" GmbH, Germany; EEW of 600 g / eq, nitrile-modified epoxy resin); Polycavyt 3632 (Schill+Seilacher "Struktol" GmbH, Germany; EEW of 600 g / eq, fatty acid-modified epoxy resin based on DGEBA).

[0057] The thermosetting resin composition preferably comprises a hardener for curing the thermosetting resin. The hardener can be used to cure the resin by applying heat energy. The heat energy can be generated, for example, by a laser beam, a convection oven, or IR radiation.

[0058] The hardener can be selected from the group comprising a hardener containing a functional group, an initiator and a catalyst, or a mixture thereof. By choosing an appropriate hardener, or a combination of two or more hardeners, the curing temperature, the speed of the curing reaction and / or the resulting crosslinking density can be adapted to the respective requirements (e.g. to the type of resin, and / or to the temperature and / or time of the heat curing in step (c) and optionally in step (b)). A di- or polyfunctional hardener is understood to be a hardener that can react with functional groups of the resin by a polyaddition and / or polycondensation reaction and can thereby be incorporated into the forming three-dimensional network. An initiator is understood to be a hardener that initiates the curing reaction of the resin by forming a reactive species (e.g.a radical and / or an ion, in particular a cation). A catalyst is understood to be a hardener that kinetically accelerates the curing reaction of the resin alone (in the case of self-crosslinking resins) or between the resin and another hardener, preferably a hardener containing a functional group.

[0059] The curing agent containing a functional group preferably has an average functionality of two to four, more preferably two to three. This allows for efficient reaction with the resin and also results in a crosslinking density within an optimal range.

[0060] The hardener preferably comprises a latent hardener. This prevents undesired pre-curing, particularly during production (e.g., extrusion), storage, and / or transport of the starting material and / or during additive manufacturing. A latent hardener is understood to be a hardener whose curing temperature is significantly above room temperature (25 °C) and which, at room temperature, undergoes no or only a slow, negligible chemical reaction. For this purpose, functional groups of the latent hardener can be provided with protective groups that are only released at a specific, elevated temperature. Curing can therefore only occur once this temperature has been reached or exceeded.

[0061] The functional group of the curing agent is preferably selected from the group comprising an amine group, an amide group, a cyanamide group (especially a dicyandiamide group), an acid group (especially a carboxyl group), an anhydride group (especially an anhydride group of a carboxylic acid), an epoxy group, a hydroxyl group, a cyanide group, a vinyl group, and an allyl group, or a mixture thereof. Other functional groups familiar to a person skilled in the art are also possible, as long as they are suitable for crosslinking the thermosetting resin used. The curing agent preferably contains at least one amine group and / or at least one amide group, more preferably two or more amine groups and / or two or more amide groups. This allows the thermosetting resin composition to be cured efficiently. The curing agent preferably has an amine number in the range of 150 to 240 mg KOH / g, more preferably 180 to 210 mg KOH / g.Then the curing reaction can take place particularly efficiently.

[0062] The hardener preferably comprises dicyandiamide and / or a polyamine; more preferably, the hardener consists of the dicyandiamide, the polyamine, or a combination thereof. This can be particularly advantageous when the resin composition comprises a polyester resin and an epoxy resin, because both of these resins can react with functional groups of the dicyandiamide or the polyamine, respectively. The polyamine can be an aliphatic polyamine, which can increase the chain mobility of the hardener at a given temperature, allowing curing to occur more quickly. Likewise, aliphatic amines are typically more reactive than aromatic amines, allowing heat curing to occur at lower temperatures, for example, already partially during additive manufacturing.It can also be advantageous if the hardener comprises a dicyandiamide, since its functional groups are only reactive at higher temperatures compared to amines, thus allowing the curing reaction to be particularly well controlled. The initiator is, for example, an ionic initiator, particularly a cationic initiator. This can catalyze, for example, a homopolymerization of the epoxy resin. The catalyst preferably comprises a Lewis acid and / or a Lewis base; in particular, the catalyst preferably comprises an imidazole group. The curing reaction can then proceed efficiently.

[0063] Preferably, the starting material comprises the curing agent in an amount of 0.1 wt% or more, more preferably 0.5 wt% or more, even more preferably 0.7 wt% or more, in particular from 0.5 to 10.0 wt%; from 0.8 to 5.5 wt%; from 1.0 to 4.0 wt%; from 0.8 to 2.0 wt%; or from 0.8 to 1.5 wt%; such as 0.9 wt%; 1.2 wt%; or 1.4 wt%, based on the total weight of the starting material. This allows a good balance to be achieved between the rate of the curing reaction and the crosslinking density.

[0064] Possible commercially available hardeners that can be used alone or in combination are Aradur 835CH (Huntsman, US; aliphatic polyamine); Aradur 2844 (Huntsman, US; dicyandiamide derivative); EPIKURE P-104 (Hexion, US; dicyandiamide); EPIKURE P-108 (Hexion, US; dicyandiamide); 2-Ethylimidazole (Donau Chemie, Austria); Technicure D-10 (A&C Catalysts, US; dicyandiamide); Dyhard 100S (Alz Chem, Germany; dicyandiamide); Dyhard UR300 (Alz Chem, Germany; uron-based initiator); Dicyanex 1200 (Evonik, Germany; dicyandiamide); CUREZOL 2MZ (Shikoku Chemical Corporation, Japan / Evonik, Germany; imidazole-based hardener); CUREZOL C17Z (Shikoku Chemical Corporation, Japan / Evonik, Germany; imidazole-based hardener); CUREZOL 1B2PZ (Shikoku Chemical Corporation, Japan / Evonik, Germany; imidazole-based hardener); OMICURE DDA 5 (Huntsman CVC Thermoset Specialties, US; dicyandiamide);OMICURE 33- DDA (Huntsman CVC Thermoset Specialities, diaminodiphenyl sulfone); Eutomer B31 (Whyte Chemicals, UK; 2-phenylimidazoline), BENOX A-75 (United Initiators, Germany; dibenzoyl peroxide); PEROXAN PK295P (PERGAN GmbH, Germany; peroxyketal).

[0065] It is preferred if the thermosetting resin composition comprises an epoxy resin and a hardener for the epoxy resin. The hardener and the epoxy resin can react with each other at elevated temperature in step (c), and optionally also in step (b), so that the epoxy resin hardens, preferably cures. The resin composition can then provide good stability.

[0066] The resin composition preferably comprises at least two thermosetting resins and a hardener. By using two thermosetting resins, the properties of the starting material can be well adapted to the respective requirements (e.g., the additive manufacturing process), particularly with regard to the processing properties of the starting material, but also with regard to the mechanical properties of the additively manufactured three-dimensional object.

[0067] Alternatively, the resin composition preferably comprises at least two thermosetting resins and at least two hardeners. Each hardener can then be adapted to one of the thermosetting resins, particularly with regard to the type and number of functional groups of the thermosetting resin. The curing rate at a given temperature and / or the resulting crosslinking density can then be adjusted even more effectively. Likewise, one of the at least two hardeners can be a hardener containing a functional group, and the other hardener can be a catalyst.

[0068] The two thermosetting resins preferably comprise at least one epoxy resin and at least one carboxylated polyester resin. This allows a particularly good balance to be achieved between the processing properties of the starting material and the mechanical properties of the three-dimensional object (before and in step (d)). Preferably, at least one hardener then contains at least one amine group, preferably an aliphatic amine group; and / or at least one amide group, preferably a dicyandiamide group. This is advantageous because the hardener can then react with both the epoxy resin and the carboxylated polyester resin.

[0069] The provided starting material further comprises a sintered material. The sintered material preferably has a density in the range of 2.0 to 16.0 g / cm 3 preferably from 2.0 to 10.0 g / cm 3 , more preferably from 2.5 to 6.0 g / cm 3, particularly preferably from 2.5 to 4.5 g / cm 3 The three-dimensional object can then maintain good dimensional stability even after the decomposition of the resin composition.

[0070] The starting material preferably comprises the sintered material in an amount of 20 vol% or more, more preferably 25 vol% or more, even more preferably 30 vol% or more, even more preferably 35 vol% or more, particularly preferably 40 vol% or more, based on the total volume of the starting material. In particular, the starting material comprises the sintered material in an amount of 25 to 65 vol%, preferably in the range of 30 to 60 vol%, more preferably in the range of 35 to 60 vol%, even more preferably in the range of 40 to 60 vol%, particularly preferably 40 to 55 vol%, based on the total volume of the starting material. This can result in a lower porosity of the three-dimensional object (because the proportion of the resin composition is lower the higher the proportion of the sintered material is) and, accordingly, a smaller change in its shape during the heat treatment in step (e), especially during sintering.The three-dimensional object can then exhibit particularly low shrinkage, which can reduce the risk of deformation.

[0071] Expressed by weight, the starting material preferably comprises the sintered material in an amount of 40 wt% or more, preferably 50 wt% or more, more preferably 55 wt% or more; preferably in the range of 40 to 95 wt%, more preferably 50 to 80 wt%, even more preferably 50 to 75 wt%, particularly preferably 53 to 70 wt%, based on the total weight of the starting material, in particular when the sintered material has a density in the aforementioned range.

[0072] The sintered material preferably has a d5o particle size of 0.02 pm to 75 pm, more preferably from 0.1 pm to 50 pm, preferably with the narrowest possible particle size distribution. The sintered material can then be mixed or co-extruded particularly well with the resin composition, so that a homogeneous starting material can be obtained. A homogeneous sintered structure can then also form during heat treatment. The sintered material (or at least 50%, preferably at least 75%, in particular at least 90% of the sintered material particles) preferably has an aspect ratio of 1:1 to 2:1, preferably 1:1 to 1.5:1 and particularly preferably 1:1 to 1.2:1. The particles are therefore preferably round to polyhedral and not fibrous particles (or not needle-shaped and / or filamentous particles (filaments)). This improves the applicability and / orThe flow of the starting material in the printer is improved compared to fibrous sintered materials. Furthermore, round to polyhedral sintered materials lead to a more homogeneous layer structure and thus to a denser component after sintering. Furthermore, this round to polyhedral particle shape means that the particles of the sintered material can be more easily completely encased by the (molten) thermosetting resin composition during the production of the starting material, at least if a production method is chosen that involves bringing the sintered material into contact, in particular mixing, in the solid state with the thermosetting resin composition in the molten state.

[0073] The sintered material is preferably a ceramic precursor. This refers, in particular, to a ceramic raw material from which a ceramic object can be produced. The method according to the invention can produce a high-precision, three-dimensional ceramic object using a ceramic precursor.

[0074] The sintered material is preferably selected from the group comprising titanium dioxide, titanium carbide, titanium carbonitride, zirconium oxide, niobium carbide, magnesium oxide, yttrium oxide, tungsten carbide, boron carbide, boron nitride, silicon carbide, silicon dioxide, silicon nitride, aluminum oxide, aluminum hydroxide, and aluminum nitride, or a mixture thereof. More preferably, the sintered material is selected from the group comprising titanium dioxide, zirconium oxide, silicon carbide, aluminum hydroxide, and aluminum oxide, or a mixture thereof. Particularly preferably, the sintered material is selected from the group comprising titanium dioxide, aluminum oxide, aluminum hydroxide, silicon carbide, or a mixture thereof. These sintered materials are particularly suitable for processing together with the resin composition in the additive manufacturing process and can be readily converted into a ceramic object by the heat treatment in step (e).The sintered material is most preferably selected from the group comprising titanium dioxide, aluminum oxide, aluminum hydroxide, or a mixture thereof, since the aforementioned advantageous effect is more pronounced for these sintered materials.

[0075] The sintered material can preferably comprise aluminum hydroxide. Heating aluminum hydroxide can lead to dehydration, forming aluminum oxide and releasing water. This can be accompanied by a greater mass loss, which can result in a somewhat higher porosity of the three-dimensional object after heat treatment (step (e)). If a three-dimensional object with a comparatively high porosity is to be produced, the use of aluminum hydroxide can therefore be advantageous. However, sintering the three-dimensional object can also increase its density and reduce its porosity without resulting in an excessive loss of geometric proportions, but rather allowing a sintered, three-dimensional object with high precision to be obtained. The sintered material particularly preferably comprises titanium dioxide and / or aluminum oxide.The three-dimensional object can then retain particularly good stability after the decomposition of the resin composition in step (d). The precision of the three-dimensional ceramic object obtained by the process according to the invention can also be further improved. Preferably, the titanium dioxide is used at least partially or exclusively in rutile form, because this form has a crystal structure well suited for heat treatment, especially sintering, in order to obtain a high-precision, three-dimensional object after step (e).

[0076] The sintered material can be coated and / or surface-modified, in particular with aluminum oxide, silicon dioxide, zirconium oxide, and / or an organic silane. The sintered material can also be coated and / or surface-modified with stearic acid. This allows the surface properties of the three-dimensional object to be influenced; in particular, its surface can be made comparatively smooth or shiny through the coating and / or surface modification. The coated and / or surface-modified sintered material preferably comprises titanium dioxide, as this is easy to coat or modify. The coated sintered material particularly preferably comprises titanium dioxide coated with zirconium oxide, as these two materials are very compatible, allowing the coating to adhere well to the sintered material.A coating and / or surface modification of the sintered material can also have a beneficial effect on compatibility with the resin composition.

[0077] Possible commercially available sintered materials that can be used alone or in combination are Portafill A40 (Sibelco Europe, Germany; synthetic aluminum hydroxide); Sepasil EK (HPF Minerals, Quarzwerke, Germany; aluminum oxide); Silatherm Plus 1432 (HPF Minerals, Quarzwerke, Germany; aluminum oxide); AA-04 (Sumitomo; Japan; aluminum oxide); AKP-20 (Sumiomo Chemical, Japan; aluminum oxide); Alodur ZWSK F500 (Imerys, France; aluminum oxide); Tioxide TR81 (Huntsman, US; surface-treated titanium dioxide); TiSelect6200 (Chemours, Netherlands; surface-treated titanium dioxide); Kronos 2300 (Kronos, US; surface-treated titanium dioxide); Kronos 2500 (Kronos, US; surface-treated titanium dioxide); Kronos 2450 (Kronos, US; surface-treated titanium dioxide); Kronos 3025 (Kronos, US; titanium dioxide); Kronos 2160 (Kronos, US; titanium dioxide); Kronos 2310 (Kronos, US; titanium dioxide); Kronos 2360 (Kronos, US, titanium dioxide); Kronos 1002 (Kronos, US;Titanium dioxide, anatase type); Aeroxide P25 (Evonik, Germany, titanium dioxide, anatase type); TiONA 592 (Tronox, US; surface-treated titanium dioxide); TiONA 826 (Tronox, US; surface-treated titanium dioxide); TiKON 33 (Tronox, US; surface-treated titanium dioxide); Silicon carbide F800 (ESK, Germany), Silicon carbide F1200 (ESK, Germany;

[0078] The starting material preferably comprises an additive. This can improve certain properties of the resin composition. The additive can be selected from the group comprising a degassing agent, an absorber, an adhesion promoter, a light stabilizer, a UV stabilizer, a structuring agent, a pigment, a filler, and a processing aid, or a mixture thereof. The starting material preferably comprises a degassing additive in order to be able to remove components present in the gaseous state in a controlled manner at the temperature used in the process. The starting material preferably comprises the degassing additive in an amount of 0.1 to 3 wt.%, more preferably 0.1 to 1.0 wt.%, based on the total weight of the starting material. Good degassing is possible by adding the degassing additive in this amount.

[0079] The starting material preferably comprises a processing aid, in particular a leveling agent, to further improve the processing properties of the resin composition, especially in additive manufacturing. The use of a leveling agent can increase the compatibility between the resin composition and the sintered material, which can improve the mechanical and surface properties of the three-dimensional object.

[0080] The starting material preferably comprises the leveling agent in an amount of 0.5 to 5.0 wt%, more preferably 2.0 to 3.0 wt%, based on the total weight of the starting material. This can increase the homogeneity of the surface of the three-dimensional object.

[0081] The flow control agent preferably comprises a silica and / or an acrylic resin. The resulting flow properties are particularly good, allowing the creation of a three-dimensional object with a very homogeneous surface. The term "acrylic resin" encompasses monomers, oligomers, and polymers containing an acrylic group or a methacrylic group.

[0082] The starting material preferably comprises a black pigment as an absorber. This can improve the energy absorption of the starting material in step (b), and accordingly its processability in additive manufacturing. This can be particularly advantageous when using a sintered material that at least partially reflects and / or absorbs the laser light used in the additive manufacturing process, which can reduce the energy input into the resin composition.

[0083] The starting material preferably comprises the black pigment in an amount of 0.1 to 5 wt%, more preferably 0.1 to 3.0 wt%, and particularly preferably 0.3 to 1.5 wt%, based on the total weight of the starting material. This allows for effective compensation of reflective or absorbent properties of the sintered material.

[0084] The black pigment preferably comprises a carbon black, particularly preferably a carbon black with an oil absorption in the range of 50 to 120 ml / 100g, preferably determined according to the standard ASTM D2414, and / or with a specific surface in the range of 100 to 300 m 2 / g, preferably determined according to ASTM D6556. Alternatively to or in combination with the black pigment, an absorber that at least partially absorbs the radiated energy in the respective wavelength range can be used.

[0085] Possible commercially available additives that can be used alone or in combination are Benzoin (Harke Chemicals, Germany; degassing additive); Ceretan MA 7020 (Münzing, Germany; degassing additive); Deurex A20K (Deurex, Germany; degassing additive); Raven Carbon Black (Birla Carbon; US; black pigment, carbon black); Printex Beads (Orion Engineered Carbons, Luxembourg; black pigment, carbon black). IRASORB CTOMIO (PC 6012 IR (Seta§ Masterbatch, Turkey; IR absorber); StanoStat CPM10F (Keeling & Walker, UK; IR absorber); Nyacol SN902SD (NYACOL Nano Technologies, US; IR absorber); IRASORB BITO (Keeling & Walker, UK; IR absorber); Nyacol SN902SD (NYACOL Nano Technologies, US; IR absorber); BYK-3900P (BYK, Germany; leveling agent); BYK-3933P (BYK, Germany; leveling agent); Modaflow Powder 6000 (Allnex, Austria; leveling agent); Resiflow PL200 (Worlee-Chemie, Germany; leveling agent).

[0086] In step (a), the starting material, which is solid at 25°C and comprises a thermosetting resin composition and a sintering material, is prepared. The prepared starting material can be obtained by any process that allows the resin composition (comprising, for example, resins, hardeners, additives) and the sintering material to be homogeneously mixed. During the preparation of the starting material, the temperature is preferably kept below the curing temperature, or a production step is carried out very quickly at a temperature at or above the curing temperature, in order to avoid or at least minimize pre-curing.

[0087] Preferably, the starting material is extruded before step (a), particularly in a twin-screw extruder. The resin composition can be in a plasticized state when mixed with the sintered material, thereby yielding a homogeneous starting material. Alternatively, only the resin composition can be extruded and the sintered material can be added at a later time, for example, after grinding the extruded resin composition, in a dry-mixing process. It can also be advantageous to perform a double extrusion, particularly if the starting material contains a high proportion of sintered material.

[0088] Preferably, a first portion of the sintered material is extruded with the resin composition in a first extrusion step, and subsequently a second portion of the sintered material is extruded with the resin composition in a second extrusion step. The first portion and the second portion of the sintered material preferably each range from 10 to 90 wt.%, more preferably from 30 to 70 wt.%, even more preferably from 40 to 60 wt.%, based on the total weight of the sintered material. Such a two-stage extrusion can significantly improve the homogeneity of the starting material. An extrudate obtained in the first extrusion step can be comminuted before the second extrusion step; in particular, it can be granulated. For example, 50 wt.% of the intended sintered material can be extruded with the resin composition in a first step.The extrudate thus obtained can then be granulated and subsequently re-extruded in a second step with the addition of the remaining 50 wt% of the intended sintered material.

[0089] The extrusion speed is preferably in the range of 400 to 1400 rpm, more preferably 600 to 1200 rpm. This allows for good mixing, while simultaneously minimizing or preventing material degradation or pre-reactions due to shear. The temperature in a feed zone of the extruder is preferably 30°C or higher, more preferably 40°C or higher, particularly preferably in the range of 35 to 45°C. The temperature in an exit zone of the extruder is preferably 80°C or higher, more preferably 90°C or higher, particularly preferably in the range of 80 to 100°C. This allows for gradual heating to bring the resin composition into a plasticized state without thermally degrading or curing it.The extrusion parameters, especially speed and temperature, also depend on the raw materials used, especially the thermosetting resin and, if present, the hardener, and must be adjusted to the respective resin composition in order to achieve sufficient dispersion and avoid undesirable pre-reactions. These adjustments are routinely carried out by a specialist.

[0090] The extruded starting material can then be ground. Preferably, the starting material is ground to a powder. The d5o particle size to which grinding is carried out can vary depending on the additive manufacturing process used in step (b).

[0091] In step (b), the three-dimensional object is produced using additive manufacturing. This not only allows the shape of the three-dimensional object to be tailored and adapted to specific requirements, but the resin composition also ensures good handling of the three-dimensional object until the resin composition decomposes. The three-dimensional object obtained in step (b) can also be referred to as a "green body" or "green compact."

[0092] Preferably, the three-dimensional object is manufactured using selective laser sintering (L-PBF). This allows even structurally complex geometries to be realized. The starting material can be applied layer by layer during selective laser sintering, and at least a portion of each layer can be irradiated with a laser, in particular with a carbon dioxide laser. The thickness of each layer is preferably in the range of 80 to 120 pm, more preferably 90 to 110 pm. This allows for a uniform energy input into the respective layer during subsequent laser irradiation.

[0093] An energy density of the laser during selective laser sintering in step (b) is preferably in the range of 30 to 290 mJ / mm 2 , preferably from 90 to 240 mJ / mm 2 , particularly preferably from 60 to 120 mJ / mm 2. As a result of this energy introduced into the starting material, the resin composition and the sintered material can at least partially bond with one another within a layer and thereby form a stable, three-dimensional object. Furthermore, depending on the reactivity of the resin composition and the respective process parameters during additive manufacturing, at least partial heat curing can occur in a layer and / or between adjacent layers, whereby the mechanical stability of the three-dimensional object can be improved; in particular, two adjacent layers can at least partially bond with one another through at least partial heat curing of the resin composition. This can, among other things, facilitate the unpacking of the three-dimensional object (i.e. the green compact) from the powder bed and / or the removal of excess starting material.

[0094] The temperature in step (b) is preferably in the range of 40 to 120°C, more preferably 60 to 100°C, and even more preferably 65 to 90°C. This allows the viscosity of the resin composition to be reduced, allowing the starting material to be processed effectively. The temperature in step (b) refers to the melt temperature of the layered starting material. In a powder bed process, this temperature is referred to as the powder bed temperature. Of course, the temperature at those locations where energy is selectively introduced for a short time, for example, by a laser, can be significantly higher for a short time.

[0095] The additive manufacturing of the three-dimensional object in step (b) can take place below a curing temperature of the resin composition, i.e., without heat-curing the resin composition. The individual layers of the three-dimensional object can be held together by additive manufacturing taking place at a temperature above the glass transition temperature of the resin (or, in the case of multiple resins, at a temperature above the glass transition temperature of at least one of the resins), so that the resin is in an entropically elastic, sticky state, whereby the layers can be well connected or bonded using the resin. This allows better control of the curing conditions in step (c), in particular the temperature and duration of heat-curing to achieve a specific degree of crosslinking of the resin composition.

[0096] Preferably, the additive manufacturing of the three-dimensional object in step (b) takes place with at least partial heat curing of the resin composition. This can improve the temperature resistance of the resin composition, so that the three-dimensional object can be better stabilized in the subsequent step (c). Since the three-dimensional object is heated in step (c) in order to (further) cure it, the viscosity of the resin composition and accordingly the dimensional stability of the three-dimensional object may initially decrease before curing can further increase the crosslinking density and thereby improve the dimensional stability. By at least partially heat curing the resin composition in step (b), an initial decrease in the viscosity of the resin composition in step (c) can be reduced and thus the dimensional stability can be improved.Likewise, partial heat curing in step (b) can improve the mechanical stability of the three-dimensional object, making it easier to unpack and handle it from a powder bed without causing damage.

[0097] Preferably, excess starting material is separated from the three-dimensional object between steps (b) and (c). Excess starting material can be recycled, preferably as a mixture with fresh starting material. It is also recommended to subject such excess starting material to a technical inspection before recycling, for example to exclude starting materials that have already reacted and / or aged from further use in additive manufacturing. Sieving to separate clumped particles from the excess starting material can also be advantageous. The separation of excess starting material is preferably carried out using compressed air and / or sandblasting. This not only enables efficient separation but can also prevent damage to or deformation of the three-dimensional object.Alternatively, the separation can also be carried out by hand or with the help of brushes and the like.

[0098] In step (c), the resin composition in the three-dimensional object is at least partially heat-cured. This further increases the mechanical properties and thus the dimensional stability of the three-dimensional object, reducing the risk of damage or deformation in subsequent steps of the process. The at least partial heat-curing of the three-dimensional object can be carried out in a convection oven. Preferably, the three-dimensional object is placed on a substrate that cannot react with the resin composition, such as a film or plate made of polytetrafluoroethylene (PTFE). If the resin composition is already partially cured in step (b), the heat-curing in step (c) is understood to be post-curing.

[0099] To at least partially cure the resin composition, in step (c) a specific elevated temperature is preferably maintained for a period of 2 hours or more, more preferably for a period in the range of 2 to 5 hours, even more preferably 3 to 4 hours. A high degree of crosslinking of the resin composition can then be achieved, provided the temperature corresponds to or exceeds the curing temperature. The actual time period can be selected depending, among other things, on the wall thickness of the three-dimensional object, the resin, and / or the curing agent.

[0100] To at least partially cure the resin composition in step (c), the resin composition can be heated to its curing temperature or above. The temperature in step (c), which is preferably maintained for the above-specified time period, is preferably 100°C or above, more preferably 130°C or above, even more preferably 150°C or above, even more preferably in the range of 100 to 250°C, particularly preferably in the range of 150 to 220°C, for example, from 150 to 200°C. Rapid curing of the resin composition can then occur. The temperature can be selected depending, among other things, on the wall thickness of the three-dimensional object and the curing temperature.

[0101] Preferably, the temperature in step (c) is 10°C or more above the curing temperature, more preferably 20°C or more, even more preferably 30°C or more. Since the curing temperature can increase with increasing crosslinking density due to the associated decrease in chain mobility of the resin composition, this can ensure that curing can be as complete as possible, provided that the temperature is maintained for a sufficiently long period of time. Preferably, the resin composition is cured in step (c). By curing the resin composition, the dimensional stability of the three-dimensional object can be particularly well maintained in the subsequent steps of the process.

[0102] The at least partial heat curing of the resin composition in step (c) preferably takes place with a gradual increase in temperature, with the temperature preferably being increased in two, three, or more steps, particularly preferably in three or four steps. This counteracts the decreasing chain mobility with increasing crosslinking density, allowing a higher crosslinking density to be achieved. Likewise, the dimensional stability of the three-dimensional object can be improved.

[0103] When increasing the temperature step by step, the temperature is preferably maintained for 30 minutes or longer in at least one step, preferably for 60 minutes or longer. Particularly preferably, the temperature is maintained for 30 minutes or longer in all steps. The temperature distribution in the three-dimensional object can become uniform at a constant temperature during this holding time, which can result in a particularly homogeneous crosslinking density of the resin composition throughout the entire three-dimensional object.

[0104] Preferably, the at least partial heat curing of the resin composition in step (c) takes place for 30 to 40 minutes at 70 to 80 °C, then for 30 to 40 minutes at 80 to 90 °C, then for 60 to 80 minutes at 110 to 120 °C, and then for 60 to 80 minutes at 180 to 190 °C. This allows a high crosslinking density to be achieved, in particular the resin composition can be cured.

[0105] Alternatively, the at least partial heat curing of the resin composition in step (c) can be carried out for 60 to 80 minutes at 80 to 90 °C, followed by 110 to 130 minutes at 110 to 120 °C, and then for 60 to 80 minutes at 210 to 220 °C. This temperature program allows for particularly effective curing of complex structures.

[0106] Preferably, the at least partial heat curing of the resin composition in the three-dimensional object in step (c) takes place in a salt bath. The three-dimensional object can then be supported by the salt bath, preventing accidental deformation, especially in complex structures. Alternatively, a sand or glass bead bath can be used; the material of the bath is unimportant, as long as it is suitable for supporting the three-dimensional object and can subsequently be separated from the three-dimensional object.

[0107] In step (d), the resin composition in the three-dimensional object is decomposed, in particular pyrolyzed and / or thermolyzed. This step can also be referred to as "debinding" or "debinding." Thermolysis can take place in air, i.e., in the presence of oxygen, while pyrolysis can take place with substantial or complete exclusion of oxygen. The resin composition is preferably thermolyzed in step (d) if the sintered material comprises an oxide. If the sintered material comprises a carbide and / or a nitride, the resin composition is preferably pyrolyzed in step (d). In each case, efficient decomposition of the resin composition is then possible.

[0108] To decompose the resin composition, in step (d) a specific elevated temperature is preferably maintained for a period of 0.5 h or more, more preferably for a period in the range of 1.0 to 20.0 h, even more preferably from 5.0 to 15.0 h, for example, 10.0 h. This allows the most complete decomposition of the resin composition to be achieved. The actual period can be selected, for example, depending on the wall thickness of the three-dimensional object.

[0109] Preferably, the temperature in step (d), which is preferably maintained for the above-specified time period, is 300°C or higher, more preferably 400°C or higher, particularly preferably 500°C or higher, and most preferably 600°C or higher. The resin composition can then be decomposed as completely as possible. The temperature in step (d) is preferably in the range of 600 to 750°C. This can result in good process economy, particularly if steps (d) and (e) are not carried out immediately one after the other. Carrying out steps (d) and (e) not immediately one after the other can be advantageous for a structurally complex three-dimensional object because the process parameters in the two steps can then be controlled independently of one another and better adapted to the respective three-dimensional object.

[0110] Preferably, steps (d) and (e) are carried out in the same process chamber. This has the advantage that the process can be simplified and made more efficient, since setting a specific temperature for this one process chamber is sufficient, and steps (d) and (e) can then be carried out directly one after the other (e.g., in the same convection oven). Heating the process chamber to a temperature intended for step (e) can begin as early as step (d). In this case, the temperature in step (d) is preferably in the range from 300 to 2000°C, preferably from 500 to 1500°C, more preferably from 600 to 1300°C, and particularly preferably from 600 to 1000°C.This not only allows the decomposition of the resin composition in step (d) to occur quickly, but also allows the heat treatment in step (e) to be carried out more efficiently, since the process chamber is then already at least partially heated to the temperature required for step (e). A further advantage of performing steps (d) and (e) in the same process chamber is that the risk of deformation of the three-dimensional object can be further reduced, since the three-dimensional object does not need to be moved between steps (d) and (e). Since steps (d) and (e) can be performed immediately one after the other, the time window for any deformation can also be reduced.

[0111] It is also possible to carry out steps (c), (d), and (e) in the same process chamber, again ensuring a gradual temperature increase so that the individual steps can take place one after the other and the geometry of the three-dimensional object can be maintained. This is only possible if no salt bath or the like is required to stabilize the three-dimensional object in step (c). In step (e), the three-dimensional object is heat-treated. This can increase the dimensional stability and durability of the three-dimensional object. The heat treatment can include sintering and / or firing. Firing is understood to mean a heat treatment in which the size of the three-dimensional object is maintained. Accordingly, a fired three-dimensional object can have a comparatively high porosity.Sintering is a heat treatment during which the densification of the sintered material causes shrinkage (i.e. volume shrinkage) of the three-dimensional object. A sintered object is smaller than before sintering and can therefore have a comparatively low porosity. Sintering can be very uniform, so that a high level of precision of the three-dimensional object can be maintained even after step (e). If a ceramic precursor is used as the sintered material, the heat treatment can produce a three-dimensional, ceramic object with a high level of precision. Particularly when using a homogeneous starting material, the shrinkage can be easily reproducible, so that it can be determined in advance by means of calculations, in particular by means of a CAD model to determine one or more shrinkage factors, and can therefore be easily compensated for.

[0112] To heat-treat the three-dimensional object, in step (e), a specific elevated temperature is preferably maintained for a period of 30 minutes or more, more preferably for a period of 60 minutes or more, and even more preferably for a period in the range of 30 to 180 minutes. In particular, if a ceramic precursor is used as the sintering material, a ceramic can then form throughout the three-dimensional object. The actual duration of the heat treatment can be adapted to the respective sintering material.

[0113] The temperature in step (e), which is preferably maintained for the above-specified time period, is preferably in the range of 500 to 2500°C, more preferably from 600 to 2200°C, even more preferably from 1000 to 2000°C, and particularly preferably from 1200 to 1800°C. The temperature can be selected depending on the particular sintered material. For example, if aluminum oxide is used as the sintered material, the temperature in step (e) is preferably in the range of 1500 to 2000°C. If titanium dioxide is used as the sintered material, the temperature in step (e) can be in the range of 700 to 1300°C.

[0114] Sintering preferably takes place in two stages, with particles of the sintered material bonding at their contact points in a first stage, which can create sinter necks; this stage is also referred to as "sintering." Shrinkage can be relatively low. In a second stage, the particles can come closer together through diffusion processes, which can lead to comparatively high shrinkage.

[0115] Alternatively, the heat treatment in step (e) may comprise infiltration, in particular liquid-phase infiltration. In this case, a liquid material, for example liquid silicon, is infiltrated into the three-dimensional object. This silicon can at least partially react with the carbon remaining from the decomposition of the resin composition to form beta-silicon carbide. If liquid silicon is used, the sintered material preferably comprises silicon carbide. Thus, a homogeneous three-dimensional ceramic object can be obtained. If the heat treatment comprises liquid-phase infiltration with a liquid material, the liquid material can fill pores of the three-dimensional object. Then, no shrinkage, or only comparatively low shrinkage, of the three-dimensional object occurs during the heat treatment.

[0116] The invention further relates to the use of the above-described starting material, which is solid at 25 °C, in additive manufacturing, in particular in selective laser sintering (L-PBF), for producing a three-dimensional object, wherein the starting material comprises the thermosetting resin composition and the sintered material, wherein the starting material comprises the sintered material in an amount of 20 vol% or more, preferably 25 vol% or more, based on the total volume of the starting material.

[0117] Due to its high precision, the three-dimensional object obtainable by the method according to the invention is well suited for use in the medical, automotive or electronics industries, in particular as an implant, prosthesis, water filter, catalyst or insulation.

[0118] The invention particularly relates to the following embodiments:

[0119] 1. A method for producing a three-dimensional object using additive manufacturing, in particular selective laser sintering (L-PBF), comprising the steps:

[0120] (a) providing a starting material which is solid at 25 °C and comprises a thermosetting resin composition and a sintered material,

[0121] (b) Additive manufacturing of the three-dimensional object,

[0122] (c) at least partially heat-curing the resin composition in the three-dimensional object,

[0123] (d) decomposition of the resin composition in the three-dimensional object, and

[0124] (e) Heat treatment of the three-dimensional object.

[0125] 2. The process according to embodiment 1, wherein the starting material is in powder form.

[0126] 3. Process according to embodiment 1 or 2, wherein the starting material has a d5o particle size of 10 to 100 pm, preferably of 20 to 60 pm, more preferably of 25 to 50 pm, in particular of 30 to 40 pm.

[0127] 4. The process according to any one of embodiments 1 to 3, wherein the starting material is solid at 30°C, more preferably at 40°C, even more preferably at 50°C.

[0128] 5. The method according to any one of embodiments 1 to 4, wherein the thermosetting resin composition at least partially envelops the sintered material. 6. The method according to any one of embodiments 1 to 5, wherein at least one particle of the sintered material is completely enveloping the thermosetting resin composition, preferably wherein at least 10% of the particles of the sintered material are completely enveloping the thermosetting resin composition, more preferably at least 20% of the particles of the sintered material, even more preferably at least 30% of the particles of the sintered material, in particular at least 40% of the particles of the sintered material or even at least 50% of the particles of the sintered material.

[0129] 7. The process according to any one of embodiments 1 to 6, wherein the starting material provided in step (a) is obtained in a process which comprises contacting, in particular mixing, the sintered material in the solid state with the thermosetting resin composition in the molten state, preferably wherein the contacting comprises co-extrusion of sintered material and resin composition or mixing of sintered material and resin composition in a heated stirred tank.

[0130] 8. The method according to any one of embodiments 1 to 7, wherein the starting material provided in step (a) is obtained by coextrusion of the thermosetting resin composition and the sintered material.

[0131] 9. The process according to any one of embodiments 1 to 8, wherein the starting material comprises the resin composition in an amount of 10 to 60 wt%, preferably 20 to 50 wt%, more preferably 20 to 45 wt%, even more preferably 25 to 45 wt%, based on the total weight of the starting material.

[0132] 10. The method according to any one of embodiments 1 to 9, wherein the thermosetting resin composition comprises an epoxy resin and / or a polyester resin.

[0133] 11. The method according to embodiment 10, wherein the thermosetting resin composition comprises an epoxy resin and a polyester resin, and wherein the weight ratio of polyester resin to epoxy resin is in the range of 2.0:1.0 to 1.0:4.0, preferably from 1.0:1.0 to 1.0:2.0, more preferably from 1.0:1.0 to 1.0:1.7, particularly preferably from 1.0:1.1 to 1.0:1.4.

[0134] 12. The process according to any one of embodiments 1 to 11, wherein a resin in the resin composition, in particular an epoxy resin and / or a polyester resin, has an average functionality of two or more, preferably in the range of two to four, more preferably two to three. 13. The process according to any one of embodiments 1 to 12, wherein the thermosetting resin composition has a curing temperature of 80°C or more, preferably in the range of 100 to 250°C, more preferably 150 to 250°C, particularly preferably 160 to 220°C.

[0135] 14. The process according to any one of embodiments 8 to 13, wherein the starting material comprises the polyester resin in an amount of 3 to 30 wt%, preferably 5 to 30 wt%, more preferably 10 to 25 wt%, particularly preferably 8 to 20 wt%, based on the total weight of the starting material.

[0136] 15. The process according to any one of embodiments 8 to 14, wherein the polyester resin has a glass transition temperature in the range of 50 to 100°C, preferably 50 to 80°C.

[0137] 16. The method according to any one of embodiments 8 to 15, wherein the polyester resin comprises an aliphatic polyester resin.

[0138] 17. The process according to any one of embodiments 8 to 16, wherein the polyester resin comprises a carboxylated and / or hydroxylated polyester resin.

[0139] 18. The process according to embodiment 17, wherein the carboxylated polyester resin has an acid number in the range of 10 to 100 mg KOH / g, preferably 20 to 90 mg KOH / g, more preferably 20 to 50 mg KOH / g, even more preferably 25 to 40 mg KOH / g.

[0140] 19. The process according to embodiment 17 or 18, wherein the hydroxylated polyester resin has a hydroxyl number in the range of 10 to 300 mg KOH / g, preferably 15 to 200 mg KOH / g, more preferably 20 to 100 mg KOH / g.

[0141] 20. The process according to any one of embodiments 10 to 19, wherein the polyester resin comprises a semi-crystalline polyester resin.

[0142] 21. The process according to embodiment 20, wherein the temperature in step (b) is in the range of 50 °C below and 20 °C above the melting temperature of the semi-crystalline polyester resin, preferably in the range of 40 °C below and 10 °C above.

[0143] 22. The process according to embodiment 20 or 21, wherein the melting temperature of the semi-crystalline polyester resin is in the range from 80 to 150°C, preferably from 90 to 130°C, more preferably from 90 to 120°C, particularly preferably from 105 to 120°C. 23. The process according to any one of embodiments 20 to 22, wherein the semi-crystalline polyester resin has a melting temperature in the range from 105 to 120°C and a viscosity at 120°C of 2.0 Pa s or below.

[0144] 24. The process according to any one of embodiments 20 to 23, wherein the resin composition comprises a semi-crystalline polyester resin and an amorphous polyester resin, preferably in a ratio of semi-crystalline polyester resin to amorphous polyester resin in the range from 3.0:1.0 to 1.0:3.0, more preferably from 2.0:1.0 to 1.0:2.0, even more preferably from 1.7:1.0 to 1.0:1.0, particularly preferably from 1.6:1.0 to 1.3:1.0.

[0145] 25. The process according to embodiment 24, wherein the glass transition temperature of the amorphous polyester resin is in the range of 35 to 70°C, preferably 45 to 65°C, more preferably 50 to 65°C.

[0146] 26. The process according to any one of embodiments 8 to 25, wherein the starting material comprises the epoxy resin in an amount of 5 to 35 wt%, preferably 10 to 30 wt%, more preferably 15 to 28 wt%, particularly preferably 15 to 25 wt%, based on the total weight of the starting material.

[0147] 27. The process according to any one of embodiments 10 to 26, wherein the epoxy resin has a glass transition temperature in the range from 60 to 150 °C, preferably from 80 to 120 °C.

[0148] 28. Process according to any one of embodiments 10 to 1, wherein the epoxy resin has a viscosity at 150°C in the range from 0.1 to 10 Pa s, preferably from 0.5 to 10 Pa s, more preferably from 1.0 to 5.0 Pa s.

[0149] 29. The process according to any one of embodiments 10 to 28, wherein the epoxy resin has an epoxy equivalent weight (EEW) of 150 g / eq or more, preferably of 350 g / eq or more, more preferably in the range of 350 to 1000 g / eq, most preferably of 350 to 700 g / eq.

[0150] 30. The method according to any one of embodiments 10 to 29, wherein the epoxy resin comprises an aromatic epoxy resin, wherein the aromatic epoxy resin is preferably selected from the group comprising a bisphenol-based epoxy resin, a novolak-based epoxy resin, a phenol-based epoxy resin and a naphthalene-based epoxy resin, or a mixture thereof, wherein the bisphenol-based epoxy resin preferably comprises a bisphenol A-based epoxy resin.

[0151] 31. The process according to any one of embodiments 10 to 30, wherein the resin composition comprises one or more epoxy resins, wherein at least one epoxy resin has an epoxy equivalent weight of 350 to 600 g / eq, preferably of 400 to 500 g / eq, and a viscosity at 150°C of 10.0 Pas or below.

[0152] 32. The method of any one of embodiments 10 to 31, wherein the resin composition comprises an elastomer-modified epoxy resin.

[0153] 33. The method of embodiment 32, wherein the resin composition further comprises an epoxy resin and / or a polyester resin, preferably an epoxy resin and / or a carboxylated polyester resin.

[0154] 34. The method according to embodiment 32 or 33, wherein the resin composition comprises the elastomer-modified epoxy resin in an amount of 1 wt% or more, preferably 5 wt% or more, more preferably 1 to 10 wt%, most preferably 5 to 10 wt%, based on the total weight of the starting material; in particular, wherein the resin composition comprises an epoxy resin and the elastomer-modified epoxy resin, and wherein the resin composition preferably comprises the elastomer-modified epoxy resin in an amount of 1 to 50 wt%, more preferably 5 to 50 wt%, more preferably 20 to 50 wt%, even more preferably 30 to 40 wt%, based on the total weight fraction of epoxy resin in the starting material.

[0155] 35. The process according to any one of embodiments 32 to 34, wherein the elastomer-modified epoxy resin has an epoxy equivalent weight of 600 g / eq or above, preferably of 800 g / eq or above, more preferably of 900 g / eq or above, even more preferably in the range of 900 to 1500 g / eq, particularly preferably in the range of 1200 to 1500 g / eq.

[0156] 36. The process according to any one of embodiments 32 to 35, wherein the glass transition temperature of the elastomer-modified epoxy resin is 60°C or higher, preferably 80°C or higher, more preferably in the range from 80 to 150°C, even more preferably from 85 to 120°C.

[0157] 37. The process according to any one of embodiments 32 to 36, wherein the elastomer-modified epoxy resin has an average functionality of two or more, preferably three or more.

[0158] 38. The process according to any one of embodiments 32 to 37, wherein the elastomer-modified epoxy resin has an elastomer content of 20 to 60 wt%, preferably 20 to 50 wt%, more preferably 25 to 40 wt%, based on the weight of the elastomer-modified epoxy resin.

[0159] 39. The process according to any one of embodiments 32 to 38, wherein the elastomer-modified epoxy resin comprises a polyacrylate rubber (ACM), an acrylonitrile-butadiene rubber (NBR) and / or a hydrogenated acrylonitrile-butadiene rubber (HNBR), particularly preferably a carboxylated NBR and / or HNBR, in particular a carboxyl-terminated acrylonitrile-butadiene rubber (CTBN).

[0160] 40. The process according to any one of embodiments 1 to 39, wherein the thermosetting resin composition comprises a curing agent, wherein the curing agent is preferably selected from the group comprising a curing agent containing a functional group, an initiator and a catalyst, or a mixture thereof.

[0161] 41. The process according to embodiment 40, wherein the curing agent containing a functional group has an average functionality of two to four, preferably of two to three.

[0162] 42. The process according to embodiment 40 or 41, wherein the curing agent contains one amine group and / or one amide group, preferably two or more amine groups and / or two or more amide groups.

[0163] 43. The process according to embodiment 42, wherein the curing agent has an amine number in the range of 150 to 240 mg KOH / g, preferably 180 to 210 mg KOH / g.

[0164] 44. The method according to any one of embodiments 40 to 43, wherein the curing agent comprises dicyandiamide and / or a polyamine, wherein the curing agent preferably consists of dicyandiamide and / or the polyamine.

[0165] 45. The process according to any one of embodiments 40 to 44, wherein the catalyst is an ionic catalyst, preferably a cationic catalyst.

[0166] 46. ​​The process according to any one of embodiments 40 to 45, wherein the starting material comprises the hardener in an amount of 0.1 wt% or more, preferably 0.5 wt% or more, more preferably 0.7 wt% or more, in particular in an amount of 0.5 to 10.0 wt%, more preferably 0.8 to 5.5 wt%, even more preferably 1.0 to 4.0 wt%, even more preferably 0.8 to 2.0 wt%, particularly preferably 0.8 to 1.5 wt%, based on the total weight of the starting material.

[0167] 47. The method according to any one of embodiments 1 to 46, wherein the thermosetting resin composition comprises an epoxy resin and a curing agent for the epoxy resin.

[0168] 48. The method according to any one of embodiments 1 to 47, wherein the resin composition comprises at least two thermosetting resins and a curing agent.

[0169] 49. The process according to any one of embodiments 1 to 48, wherein the resin composition comprises at least two thermosetting resins and at least two curing agents. 50. The process according to embodiment 48 or 49, wherein the two thermosetting resins comprise at least one epoxy resin and at least one carboxylated polyester resin, wherein at least one curing agent preferably contains at least one amine group and / or at least one amide group, wherein the amine group is preferably an aliphatic amine group and / or wherein the amide group is preferably a dicyandiamide group.

[0170] 51. The method according to any one of embodiments 1 to 50, wherein the sintered material has a density in the range of 2.0 to 16.0 g / cm 3 preferably from 2.0 to 10.0 g / cm 3 , preferably from 2.5 to 6.0 g / cm 3 , particularly preferably from 2.5 to 4.5 g / cm 3 .

[0171] 52. The method according to any one of embodiments 1 to 51, wherein the starting material comprises the sintered material in an amount of 20 vol% or more, preferably 25 vol% or more, more preferably 30 vol% or more, even more preferably 35 vol% or more, particularly preferably 40 vol% or more, based on the total volume of the starting material.

[0172] 53. The method according to embodiment 52, wherein the starting material comprises the sintered material in an amount in the range of 25 to 65 vol%, more preferably in the range of 30 to 60 vol%, even more preferably in the range of 35 to 60 vol%, even more preferably in the range of 40 to 60 vol%, particularly preferably in the range of 40 to 55 vol%, based on the total volume of the starting material.

[0173] 54. The process according to any one of embodiments 1 to 53, wherein the starting material comprises the sintered material in an amount of 40 wt% or more, preferably 50 wt% or more, more preferably 55 wt% or more; preferably in the range of 40 to 95 wt%, more preferably 50 to 80 wt%, even more preferably 50 to 75 wt%, particularly preferably 53 to 70 wt%, based on the total weight of the starting material.

[0174] 55. The method according to any one of embodiments 1 to 54, wherein the sintered material has a d5o particle size of 0.02 pm to 75 pm, more preferably of 0.1 pm to 50 pm.

[0175] 56. The method according to any one of embodiments 1 to 55, wherein the sintered material is a ceramic precursor.

[0176] 57. The method according to any one of embodiments 1 to 56, wherein the sintered material is selected from the group comprising titanium dioxide, titanium carbide, titanium carbonite, niobium carbide, magnesium oxide, yttrium oxide, zirconium oxide, tungsten carbide, boron carbide, boron nitride, silicon carbide, silicon dioxide, silicon nitride, aluminum oxide, aluminum hydroxide, and aluminum nitride, or a mixture thereof; more preferably from the group comprising titanium dioxide, zirconium oxide, silicon carbide, aluminum hydroxide, and aluminum oxide, or a mixture thereof. 58. The method according to embodiment 57, wherein the sintered material comprises, in particular consists of, titanium dioxide, aluminum hydroxide, and / or aluminum oxide; and / or wherein the sintered material is coated and / or surface-modified, preferably with aluminum oxide, silicon dioxide, zirconium oxide, stearic acid, and / or an organic silane.

[0177] 59. The method according to embodiment 58, wherein the sintered material comprises titanium dioxide and / or aluminum oxide, and preferably consists of titanium dioxide and / or aluminum oxide.

[0178] 60. The method according to embodiment 58, wherein the sintered material comprises titanium dioxide, and preferably consists of titanium dioxide.

[0179] 61. The method according to embodiment 58, wherein the sintered material comprises aluminum hydroxide, and preferably consists of aluminum hydroxide.

[0180] 62. The method according to embodiment 58, wherein the sintered material comprises aluminum oxide, and preferably consists of aluminum oxide.

[0181] 63. The method according to any one of embodiments 1 to 62, wherein the sintered material is coated and / or surface-modified, preferably with aluminum oxide, silicon dioxide, zirconium oxide, stearic acid and / or an organic silane.

[0182] 64. Process according to one of embodiments 1 to 63, wherein at least 50%, preferably at least 75%, in particular at least 90% of the sintered material particles have an aspect ratio of 1:1 to 2:1, preferably of 1:1 to 1.5:1 and particularly preferably of 1:1 to 1.2:1.

[0183] 65. The method according to any one of embodiments 1 to 63, wherein the sintered material has an aspect ratio of 1:1 to 2:1, preferably of 1:1 to 1.5:1 and particularly preferably of 1:1 to 1.2:1.

[0184] 66. The process according to any one of embodiments 1 to 66, wherein the starting material comprises an additive.

[0185] 67. The method of embodiment 66, wherein the additive comprises a degassing additive.

[0186] 68. The process according to embodiment 67, wherein the starting material comprises the degassing additive in an amount of 0.1 to 3 wt%, more preferably 0.1 to 1.0 wt%, based on the total weight of the starting material. 69. The process according to embodiment 67 or 68, wherein the degassing additive is benzoin.

[0187] 70. The method of any one of embodiments 66 to 69, wherein the additive comprises a leveling agent.

[0188] 71. The process of embodiment 70, wherein the starting material comprises the leveling agent in an amount of 0.5 to 5.0 wt%, more preferably 2.0 to 3.0 wt%, based on the total weight of the starting material.

[0189] 72. The method of embodiment 70 or 71, wherein the leveling agent comprises a silica and / or an acrylic resin.

[0190] 73. The method of any one of embodiments 70 to 72, wherein the starting material comprises a black pigment.

[0191] 74. The process of embodiment 73, wherein the starting material comprises the black pigment in an amount of 0.1 to 5 wt%, preferably 0.1 to 3.0 wt%, more preferably 0.3 to 1.5 wt%, based on the total weight of the starting material.

[0192] 75. The method of embodiment 73 or 74, wherein the black pigment comprises a carbon black.

[0193] 76. Process according to any one of embodiments 1 to 75, wherein the starting material is extruded before step (a), preferably wherein the starting material is ground after extrusion; wherein particularly preferably a first part of the sintered material is extruded with the resin composition in a first extrusion step, and subsequently a second part of the sintered material is extruded with the resin composition in a second extrusion step, wherein the first part and the second part of the sintered material are preferably each in the range from 10 to 90 wt%, more preferably from 30 to 70 wt%, even more preferably from 40 to 60 wt%, based on the total weight of the sintered material.

[0194] 77. The method according to any one of embodiments 1 to 76, wherein the three-dimensional object in step (b) is manufactured using selective laser sintering (L-PBF).

[0195] 78. The method of embodiment 77, wherein a laser energy density in step (b) is in the range of 30 to 290 mJ / mm 2 preferably from 90 to 240 mJ / mm 2 , preferably from 60 to 120 mJ / mm 2 .

[0196] 79. The method according to any one of embodiments 1 to 78, wherein the temperature in step (b) is in the range from 40 to 120°C, preferably from 60 to 100°C, more preferably from 65 to 90°C. 80. The method according to any one of embodiments 1 to 79, wherein the additive manufacturing of the three-dimensional object in step (b) takes place below a curing temperature of the resin composition.

[0197] 81. The method according to any one of embodiments 1 to 80, wherein the additive manufacturing of the three-dimensional object in step (b) is carried out with at least partial heat curing of the resin composition.

[0198] 82. The method according to embodiment 81, wherein between steps (b) and (c) a resin composition which is not at least partially cured is separated from the three-dimensional object, preferably by means of compressed air or by sandblasting.

[0199] 83. The process according to any one of embodiments 1 to 82, wherein the temperature in step (c) is 100°C or above, more preferably 130°C or above, even more preferably 150°C or above, even more preferably in the range from 100 to 250°C, even more preferably from 150 to 220°C, particularly preferably from 150 to 200°C.

[0200] 84. The process according to any one of embodiments 1 to 83, wherein in step (c) a certain temperature is maintained for a period of 2 hours or more, preferably for a period in the range of 2 to 5 hours, more preferably 3 to 4 hours.

[0201] 85. The process according to any one of embodiments 1 to 84, wherein the at least partial heat curing of the resin composition in step (c) is carried out with a stepwise increase in temperature, wherein the temperature in step (c) is preferably increased in two, three or more steps, particularly preferably in three or four steps.

[0202] 86. The method of embodiment 85, wherein the temperature is maintained for 30 minutes or longer, preferably for 60 minutes or longer, in at least one step.

[0203] 87. The method according to embodiment 85 or 86, wherein the at least partial heat curing of the resin composition in step (c) is carried out for 30 to 40 minutes at 70 to 80°C, then for 30 to 40 minutes at 80 to 90°C, then for 60 to 80 minutes at 110 to 120°C, and then for 60 to 80 minutes at 180 to 190°C.

[0204] 88. The method according to embodiment 85 or 87, wherein the at least partial heat curing of the resin composition in step (c) takes place for 60 to 80 minutes at 80 to 90°C, then for 110 to 130 minutes at 110 to 120°C, and then for 60 to 80 minutes at 210 to 220°C. 89. The method according to any one of embodiments 1 to 88, wherein the at least partial heat curing of the resin composition in the three-dimensional object in step (b) takes place in a salt bath, in a sand bath, or in a glass bead bath.

[0205] 90. The process according to any one of embodiments 1 to 89, wherein the temperature in step (c) is 10°C or more above the curing temperature, more preferably 20°C or more, even more preferably 30°C or more.

[0206] 91. The method according to any one of embodiments 1 to 90, wherein the resin composition is cured in step (c).

[0207] 92. The method according to any one of embodiments 1 to 91, wherein the resin composition in the three-dimensional object is pyrolyzed in step (d).

[0208] 93. The process according to any one of embodiments 1 to 92, wherein a certain temperature in step (d) is maintained for a period of time of 0.5 h or more, more preferably for a period of time in the range of 1.0 to 20.0 h, even more preferably from 5.0 to 15.0 h.

[0209] 94. The process according to any one of embodiments 1 to 93, wherein the temperature in step (d) is 300°C or above, preferably 400°C or above, more preferably 500°C or above, even more preferably 600°C or above; particularly preferably in the range from 600 to 750°C.

[0210] 95. The method according to any one of embodiments 1 to 94, wherein steps (d) and (e) are carried out in the same process space, preferably wherein steps (c), (d) and (e) are carried out in the same process space.

[0211] 96. The process of embodiment 95, wherein the temperature in step (d) is in the range from 300 to 2000°C, preferably from 500 to 1500°C, more preferably from 600 to 1300°C, even more preferably from 600 to 1000°C.

[0212] 97. The method according to any one of embodiments 1 to 96, wherein the heat treatment of the three-dimensional object in step (e) comprises sintering and / or firing, preferably sintering.

[0213] 98. The process according to any one of embodiments 1 to 97, wherein a certain temperature in step (e) is maintained for a period of 30 minutes or more, preferably for a period of 60 minutes or more, more preferably for a period in the range of 30 minutes to 180 minutes. 99. The process according to any one of embodiments 1 to 98, wherein the temperature in step (e) is in the range of 500 to 2500°C, preferably from 600 to 2200°C, more preferably from 1000 to 2000°C, even more preferably from 1200 to 1800°C.

[0214] 100. Use of a starting material which is solid at 25 °C in additive manufacturing, in particular in selective laser sintering (L-PBF), for producing a three-dimensional object, wherein the starting material comprises a thermosetting resin composition and a sintering material, wherein the starting material comprises the sintering material in an amount of 20 vol% or more, preferably 25 vol% or more, based on the total volume of the starting material.

[0215] 101. Use according to embodiment 100, wherein the starting material comprises the sintered material in an amount of 30 vol% or more, preferably 35 vol% or more, more preferably 40 vol% or more, based on the total volume of the starting material.

[0216] 102. Use according to embodiment 100 or 101, wherein the sintered material is selected from the group comprising titanium dioxide, zirconium oxide, silicon carbide, aluminum oxide, aluminum hydroxide and mixtures thereof.

[0217] 103. Use according to any one of embodiments 100 to 102, wherein the resin composition comprises at least two thermosetting resins and at least one curing agent.

[0218] 104. Use according to any one of embodiments 100 to 103, wherein the starting material comprises a black pigment.

[0219] 105. Use according to any one of embodiments 100 to 104, wherein the starting material has one or more features of embodiments 2 to 99.

[0220] Definitions

[0221] [Additive Manufacturing] This term refers to a process that produces a three-dimensional object from 3D model data by combining material layer by layer, in contrast to subtractive and forming manufacturing methods (DIN EN ISO / ASTM 52900:2022-03).

[0222] [Amine number] The amine number is defined as the amount of potassium hydroxide (KOH) in mg equivalent to the amine content of 1 g of a chemical substance containing free amine groups. The amine number of a component of the starting material (e.g., the amine number of a hardener) can be determined according to DIN EN ISO 9702:1998. If, for example, a mixture of two or more hardeners containing amine groups is used, the specified amine number is the average value of the mixture. [Starting material] This term refers to a bulk raw material that can be used for the build-up process in additive manufacturing. This includes starting materials in various forms, e.g., liquids, powders, suspensions, filaments, or films (DIN EN ISO / ASTM 52900:2022-03). Here, "a starting material that is solid at 25°C" preferably refers to a starting material that is solid at 25°C under atmospheric pressure (101325 Pa).

[0223] [Epoxy resin] This term refers to a monomer, oligomer, or polymer containing one or more epoxy groups. The terms epoxy and epoxy resin can be used synonymously. In this description, the epoxy resin can be a monomer, oligomer, polymer, or a mixture thereof. Unless expressly stated otherwise, the term "epoxy resin" in the singular can encompass one or more epoxy resins.

[0224] [Functionality, average] The average functionality of a resin or a hardener is understood to be the average number of functional groups per molecule of the resin or hardener, which functional groups can react with other functional groups, e.g. of a resin or hardener, under appropriate conditions, e.g. under the supply of thermal energy.

[0225] [Glass transition temperature] The glass transition temperature (Tg) characterizes the temperature range in which a polymer transitions from the energy-elastic (i.e., glassy) state to the entropy-elastic (i.e., rubbery) state. In this description, the inflection point of the endothermic step indicating the glass transition is referred to as Tg. Only endothermic steps above 0 °C are considered Tg. The Tg can be determined according to ISO 11357-2:2014 using a DSC measurement. The DSC measurement can be carried out under nitrogen. A heating and cooling rate of 20 K / min and a sample weight of 10 to 15 mg can be used. In a first heating step, the thermal history can be eliminated, and the Tg can then be determined from a second heating curve. DSC measurements can be carried out, in particular, using the temperature program shown in Table 3 of this description.Steps 1-6 of this temperature program can be performed to determine the Tg of an uncured, at least partially cured, or cured resin composition, or the Tg of an individual component (e.g., a resin or curing agent). Steps 1-10 of the temperature program can be performed to determine a Tg of the resin composition from the heating curve of step 9, which can be compared to the Tg of an at least partially thermoset resin composition in the three-dimensional object. Steps 11-13 can be performed to confirm that the previously completed curing was complete. [Curing agent] The term curing agent (also called "crosslinker") is understood to mean a component of the starting material that can react with a thermosetting resin or initiate or accelerate a chemical reaction of the resin to form a three-dimensional network (e.g., a thermoset).

[0226] [Curing] This term (also referred to as "curing" or "crosslinking") refers to the treatment of a thermosetting resin composition with energy (e.g. thermal energy or radiation) such that curable components of the resin composition (e.g. resins with functional, curable groups) are stimulated to react and the resin composition is brought into an at least partially cured state. The resin composition can also be not only partially cured, but fully cured. This means that no curing peak is then visible in a heating curve of a subsequent DSC measurement, and that the difference in the glass transition temperature of the resin composition in two consecutive heating curves is preferably less than 4 °C, more preferably less than 2 °C.

[0227] [Curing temperature] The curing temperature is defined as the temperature at which the thermosetting resin composition can be cured. The curing temperature depends, among other things, on the resin and, if applicable, the curing agent contained in the starting material. The curing temperature of the resin composition can be determined by DSC measurement, in particular according to ISO 11357-2:2014. The measurement can be carried out under nitrogen. A heating and cooling rate of 20 K / min and a sample weight of 10 to 15 mg can be used. The onset of the curing peak of the resin composition in the first heating curve indicates the beginning of curing and is considered the curing temperature.

[0228] [Resin composition, thermosetting] This term refers to a resin composition comprising a thermosetting resin (ie a monomer, an oligomer and / or a polymer having at least one functional, thermosetting group) which can react with another functional group (eg a hardener) under the supply of thermal energy so that a three-dimensional network (ie a thermoset) can be formed.

[0229] [Hydroxyl number] The hydroxyl number is defined as the amount of potassium hydroxide (KOH) in mg required to neutralize the amount of acetic acid absorbed during the acetylation of 1 g of a chemical substance containing free hydroxyl groups. The hydroxyl number of components of the starting material (e.g. the hydroxyl number of a hydroxylated polyester resin) can be determined according to the standard DIN EN ISO 4629-2:2016-07. If, for example, a mixture of two or more hydroxylated polyester resins is used, the stated hydroxyl number is the mean value of the mixture. [Homogeneity] The term homogeneity refers to the components of a starting material, e.g. a thermosetting resin and a hardener, being in a well-dispersed state with a random distribution.

[0230] [Polyester resin] This term refers to an oligomer or a polymer having at least two ester groups in its backbone. A polyester resin can be synthesized, for example, by a polycondensation reaction of a di-, tri-, or polyfunctional carboxylated monomer and a di-, tri-, or polyfunctional hydroxyfunctional monomer. The terms polyester, polyester resin, and polyester polymer can be used synonymously. In the present description, the polyester resin can be an oligomer, a polymer, or a mixture thereof. Unless expressly stated otherwise, the term "polyester resin" in the singular can encompass one or more polyester resins.

[0231] [Polymer, amorphous] An amorphous polymer is one that is not capable of crystallizing. A polymer is amorphous if, after eliminating its thermal history, it exhibits no discernible crystallization or melting peak, which can be determined by DSC measurement.

[0232] [Polymer, semi-crystalline] A semi-crystalline polymer is defined as one that, in its solid state, exhibits both amorphous and crystalline domains. A polymer is semi-crystalline if, after eliminating its thermal history, it exhibits a crystallization peak or melting peak, which can be determined by DSC measurement.

[0233] [Acid value] The acid value is defined as the amount of potassium hydroxide (KOH) in mg required to neutralize acid groups in a chemical substance. The acid value of components of the starting material (e.g., the acid value of a carboxylated polyester resin) can be determined according to DIN EN ISO 2114:2002-06. If, for example, a mixture of two or more carboxylated polyester resins is used, the stated acid value is the average value of the mixture.

[0234] [Melting temperature] The melting temperature (Tm) of a chemical substance is the temperature at which its state changes from solid to liquid. Since semi-crystalline polymers have a melting range, the Tm of a semi-crystalline polymer is the temperature of the endothermic melting peak of the polymer's crystalline domains. The Tm can be determined by DSC measurement according to ISO 11357-3:2018. The measurement can be performed under nitrogen. A heating and cooling rate of 20 K / min and a sample weight of 10 to 15 mg can be used. In a first heating step, the thermal history can be eliminated, and the Tm can then be determined from a second heating curve. In particular, the DSC measurement can be performed using the temperature program according to Table 3 of this description, where the Tm can be determined from the heating curve of step 5.[Aspect ratio] The aspect ratio of particles is the proportional ratio of the side width to the side height. The aspect ratio can be determined according to ISO 9276-6:2008.

[0235] [Viscosity] The dynamic viscosity of resins, such as epoxy resins or polyester resins, can be measured using a cone-and-plate viscometer (Brookfield CAP 2000+ from Brookfield Ametek, US) equipped with a spindle 06 (CAP-S-06). Depending on the expected dynamic viscosity of the resin sample, other spindles can also be used (e.g., spindle 02 for an expected dynamic viscosity of less than 0.5 Pa s at 150 °C). The viscometer plate can be preheated to 150 °C (or another desired measurement temperature), and a sufficient amount of sample can be applied to it (approximately 0.1 g of sample when using spindle 06). The sample can then be held at the desired temperature, e.g., 150 °C, and the measurement can be started at a rotation speed of 700 revolutions per minute for a period of 115 seconds.The dynamic viscosity at 150 °C can then be read on the device's display. Additional information can be found in the device's instruction manual (Manual no. M02-313-I0916; available at https: / / www.brookfieldengineering.com / - / media / ametekbrookfield / manuals / lab%20viscometers / cap2000%20instructions.pdf?la=en).

[0236] The viscosity of the starting material can be determined according to ISO 6721-10:2015. The measurement can be performed, for example, using the AR2000ex plate rheometer from TA Instruments (US).

[0237] Figures

[0238] Figures 1-3 show DSC curves of starting materials according to Example 1 (Fig. 1), Example 2 (Fig. 2), and Example 3 (Fig. 3). Each shows a first, a second, and a third heating curve (named with the suffixes "_1," "_2," and "_3").

[0239] Fig. 4 shows DSC curves of samples of heat-cured, three-dimensional objects produced from the starting materials according to Examples 1-3. A first heating curve is shown in each case.

[0240] Fig. 5-7 show TGA curves of samples of thermoset three-dimensional objects prepared from the starting materials according to Example 1 (Fig. 1), Example 2 (Fig. 6) and Example 3 (Fig. 7).

[0241] Fig. 8 shows images of a three-dimensional object produced from the starting material according to Example 1, after steps (b), (c), and (e) of the process. Figs. 9-10 show SEM images of sintered, three-dimensional objects produced from the starting materials according to Example 1 (Fig. 9) and Example 2 (Fig. 10).

[0242] Fig. 11 shows photographs of three-dimensional objects produced from the starting materials according to Example 2 and Example 3, after step (b) of the process.

[0243] Examples

[0244] The invention is further explained below with reference to examples, to which the invention is not intended to be limited.

[0245] (I) Production of starting materials

[0246] The starting materials according to Table 1 were prepared, with the starting material according to Example 1 containing titanium dioxide in an amount of 25.8 vol% (equivalent to 54.6 wt%), and the starting material according to Examples 2 and 3 containing aluminum hydroxide (ATH) in an amount of 37.6 vol% and 37.7 vol% (equivalent to 55.0 wt% and 55.1 wt%), respectively. First, the components were premixed and then extruded using a twin-screw extruder (ZSK-18, Coperion, Germany). In Example 3, 50 wt% of the intended amount of ATH was added to the resin composition in a first extrusion step, and the remaining amount of ATH (50 wt%) was added in a further extrusion step.

[0247] For all examples, a speed of 600 to 1200 rpm, an extruder inlet temperature of 40 °C, and an extruder outlet temperature of 80 °C were used; for example 3, these parameters were chosen for both extrusion steps. The extrudates were then cooled, coarsely crushed, and then milled with a mill (ICM 158 CX, Neuman & Esser, Germany) with an air flow of 2.4 m 3 / min until a d5o particle size of 100 pm or less was achieved. In the case of Example 1, a d5o particle size of 39 pm was obtained; for Example 2, the d5o particle size was 36 pm; and for Example 3, it was 32 pm. The resulting starting materials were subsequently used for the process according to the invention.

[0248] Table 1: Compositions of starting materials according to the invention (quantities in wt%)

[0249] (II) Production of thermosetting, three-dimensional objects

[0250] The powdered starting materials according to Examples 1, 2, and 3 were used for additive manufacturing using L-PBF. The printing process was carried out using a ProMaker P1000 printer (Prodways, France) or an HT252P printer (Farsoon Europe, Germany). The respective starting materials were smoothly applied layer by layer to a thickness of 100 μm on the printer's build platform. The three-dimensional object was constructed by selectively irradiating the smooth powder surface with a carbon dioxide laser with a wavelength of 10.6 pm at a laser power of 16 W (ProMaker P1000) or 31 W (HT252P), a scan speed of 3.5 m / s (ProMaker P1000) or 7.6 m / s (HT252P), and a scan line spacing of 0.15 mm (ProMaker P1000) or 0.13 mm (HT252P). The resulting laser energy density was at a similar level for both printing variants, namely 91.4 mJ / mm 2 (ProMaker P1000) or 108.3 mJ / mm 2(HT252P). The temperature on the build platform, the so-called powder bed temperature, was 72 °C for examples 1 and 3 and 66 °C for example 2. Tensile test specimens with the test specimen shape described in DIN EN ISO 3167 with a total length of 150 mm, a maximum width of 20 mm, and a thickness of 4 mm for testing according to DIN EN ISO 527-1:2019 were printed. Cubes with an edge length of 12 mm were also printed. After printing, excess starting material was removed using brushes, compressed air, and sandblasting.

[0251] (III) Heat curing of the three-dimensional objects

[0252] The three-dimensional objects printed using the starting materials according to Examples 1, 2, and 3 were heat-cured in a convection oven (Carbolite PF200, Carbolite Gero, Germany) using the temperature program shown in Table 2. They were then cooled in the convection oven to approximately 120 °C and then cooled in ambient air to room temperature (approximately 25 °C). The resin compositions in the respective three-dimensional objects were fully cured.

[0253] The temperature-dependent curing behavior of the resin compositions was determined using DSC. For the DSC measurements, samples of the starting materials as well as samples of the printed and heat-cured tensile specimens from Examples 1, 2, and 3 with a mass ranging from 10 to 15 mg were subjected to the temperature program specified in Table 3. The DSC measurements were performed in accordance with ISO 11357-2:2014 using a DSC 204 Fl Phoenix (Netzsch, Germany) under a nitrogen atmosphere.

[0254] The first heating curve of the starting materials up to 250 °C (step 5 of Table 3) shows an exothermic curing peak with an onset at approximately 130 °C (Example 1, see Fig. 1), approximately 140 °C (Example 1, see Fig. 2), and approximately 160 °C (Example 3, see Fig. 3). In the second heating curve up to 250 °C (step 9 of Table 3), no exothermic peak is present. The third heating curve essentially corresponds to the second heating curve, indicating that the resin composition was already fully cured before the second heating step (see Figs. 1-3).

[0255] Heating curves of the samples of the thermoset, three-dimensional objects confirm that the curing of the resin composition was complete during the thermoset of these objects: As can be seen from Fig. 4, the initial heating curves of all samples (based on the starting materials of Examples 1-3) already show no exothermic peaks; heating was carried out according to step 5 of Table 3 up to 250 °C. Therefore, the measurements were terminated after step 6.

[0256] Table 2: Temperature program for heat curing of the resin composition

[0257] Table 3: Temperature program of the DSC measurements

[0258] (IV) Mechanical characterization of the three-dimensional objects before and after heat curing

[0259] The mechanical characterization of the three-dimensional objects before and after heat curing was performed using a tensile testing machine (Shimadzu AGS-10kN XD Series, Shimadzu, Germany) according to DIN EN ISO 527-1:2019. A clamping length of 125 mm and a tensile speed of 1 mm / min were used. The tensile test results are presented in Table 4.

[0260] Table 4: Mechanical properties of the three-dimensional objects before and after heat curing

[0261] A comparison of the results in Table 4 clearly shows the effect of heat curing the resin compositions on the mechanical properties of the three-dimensional object. These properties can be significantly enhanced by the formation of a three-dimensional network. The increase in mechanical properties has a positive effect on the stability of the three-dimensional object up to and even during the decomposition of the resin composition.

[0262] (V) Decomposition of the resin composition in the three-dimensional object

[0263] After heat curing, the cube-shaped, three-dimensional objects according to Examples 1-3 were heated in a furnace (Phoenix Microwave Muffle Furnace, CEM, Germany) at 10 K / min to a temperature of 600 °C, which temperature was then maintained for 10 h to decompose the respective resin composition. During heating, a gradual, continuous decomposition of the resin composition occurred, as evident from the TGA curves (Fig. 5 for Example 1, Fig. 6 for Example 2, Fig. 7 for Example 3). The TGA measurements were performed with the TGA2 (Mettler Toledo, Germany) in synthetic air. A sample of the three-dimensional object (approximately 10 mg, taken from a printed tensile bar) was heated in synthetic air from 50 to 700 °C at 20 K / min. The onset of decomposition was 330 °C (Example 1, see Fig. 5).In the case of the starting materials according to Examples 2 and 3, which contain aluminum hydroxide as the sintering material, dehydration of the aluminum hydroxide and the formation of aluminum oxide occurred before the decomposition of the resin composition at a temperature of approximately 250 °C, resulting in additional weight loss (see Figs. 6 and 7). However, this did not reduce the stability of the three-dimensional object. In fact, the cured resin composition can achieve good stability even at higher temperatures, which only decreases with progressive decomposition of the resin composition upon further heating. The mass loss at a temperature of 700 °C was approximately 45 wt% (Example 1), approximately 62 wt% (Example 2), and approximately 61.6 wt% (Example 3).

[0264] (VI) Heat treatment of the three-dimensional object

[0265] Following decomposition of the resin composition, the three-dimensional objects were heat-treated. This was achieved by sintering at 1200 °C or 1640 °C for 48 h at atmospheric pressure (approx. 1013 mbar) in air in a muffle furnace (Nabertherm P310, Nabertherm, Germany). Table 5 lists the average shrinkage of the sintered objects relative to their initial size. Table 5 also shows the density of the three-dimensional objects and the ratio to the actual density of the respective sintered material (titanium dioxide or aluminum oxide formed by dehydration of aluminum hydroxide at elevated temperature). The shrinkage of the object is also illustrated in Fig. 8, which shows a cube-shaped object produced from the starting material according to Example 1 after each of steps (b), (c), and (e).

[0266] The three-dimensional objects sintered at 1200 °C were subsequently examined using a JEO JSM-ITIOO scanning electron microscope (Jeol, Japan) equipped with a secondary electron detector. The scanning electron microscopy (SEM) images clearly show that a homogeneous sintered structure was formed during sintering (Fig. 9 for Example 1, Fig. 10 for Example 2).

[0267] Table 5: Properties of the three-dimensional objects after heat treatment at different temperatures

[0268] 1 The theoretical density of rutile is 4.24 g / cm 3 , the theoretical density of aluminum oxide at 3.94 g / cm 3

[0269] 2 Swelling and spreading in x- and y-direction already during heat curing

[0270] As can be seen from Table 5, porous three-dimensional, ceramic objects can be specifically produced by using aluminum hydroxide as a sintering material. The open porosity is 48.9 vol% and 54.6 vol% for Examples 2 and 3, respectively, compared to approximately 22 vol% for Example 1. In the case of Example 3, the thermal treatment of the objects (steps (c), (d) and (e) of the process) results in deformation of these objects in the x and y directions. Such deformation can be reduced or prevented by using an appropriately adapted starting material and / or by appropriate scaling of the object to be printed. The influence of the starting material is illustrated in Fig. 11, which shows cube-shaped objects with starting compositions according to Examples 2 and 3 after additive manufacturing (i.e., after step (b)) of the process. The dimensional stability of the object of Example 2 is comparatively high.

Claims

Patent claims 1. A method for producing a three-dimensional object using additive manufacturing, in particular selective laser sintering (L-PBF), comprising the steps: (a) providing a starting material which is solid at 25 °C and comprises a thermosetting resin composition and a sintered material, (b) Additive manufacturing of the three-dimensional object, (c) at least partially heat-curing the resin composition in the three-dimensional object, (d) decomposition of the resin composition in the three-dimensional object, and (e) Heat treatment of the three-dimensional object.

2. The method according to claim 1, characterized in that the additive manufacturing of the three-dimensional object in step (b) is carried out with at least partial heat curing of the resin composition.

3. A process according to claim 1 or 2, characterized in that the at least partial heat curing of the resin composition in step (c) is carried out with a gradual increase in temperature.

4. Method according to one of claims 1 to 3, characterized in that the sintered material is a ceramic precursor.

5. The method according to claim 4, characterized in that the sintered material is selected from the group comprising titanium dioxide, zirconium oxide, silicon carbide, aluminum hydroxide and aluminum oxide, or a mixture thereof.

6. The method according to claim 5, characterized in that the sintered material is selected from the group comprising titanium dioxide, aluminum hydroxide and aluminum oxide, or a mixture thereof.

7. Process according to one of claims 1 to 6, characterized in that the starting material comprises a black pigment.

8. A method according to any one of claims 1 to 7, characterized in that the thermosetting resin composition comprises an epoxy resin and a hardener for the epoxy resin, wherein the hardener preferably contains at least one amine group and / or at least one amide group.

9. A method according to any one of claims 1 to 8, characterized in that the resin composition comprises at least two thermosetting resins and a hardener.

10. Method according to one of claims 1 to 9, characterized in that the Resin composition comprising at least two thermosetting resins and at least two hardeners.

11. Method according to one of claims 1 to 10, characterized in that the The starting material comprises the sintered material in an amount of 20 vol% or more, based on the total volume of the starting material.

12. The method according to claim 11, characterized in that the starting material comprises the sintered material in an amount of 25 vol% or more, preferably 30 vol% or more, more preferably 35 vol% or more, particularly preferably 40 vol% or more; preferably in the range of 25 to 65 vol%, more preferably in the range of 30 to 60 vol%, even more preferably in the range of 35 to 60 vol%, even more preferably in the range of 40 to 60 vol%, particularly preferably from 40 to 55 vol%, based on the total volume of the starting material.

13. Method according to one of claims 1 to 12, characterized in that the thermosetting resin composition at least partially envelops the sintered material.

14. The method according to any one of claims 1 to 13, characterized in that the thermosetting resin composition comprises a hardener, wherein the hardener is preferably selected from the group comprising a hardener containing a functional group, an initiator and a catalyst, or a mixture thereof.

15. Process according to one of claims 8 to 14, characterized in that the at least two thermosetting resins comprise at least one epoxy resin and at least one carboxylated polyester resin, and in that at least one hardener preferably contains at least one amine group and / or at least one amide group.

16. Use of a starting material which is solid at 25 °C in additive manufacturing, in particular in selective laser sintering (L-PBF), for producing a three-dimensional object, wherein the starting material comprises a thermosetting resin composition and a sintering material, characterized in that the starting material comprises the sintering material in an amount of 20 vol% or more, based on the total volume of the starting material.

17. Use according to claim 16, characterized in that the starting material comprises the sintered material in an amount of 25 vol% or more, preferably 30 vol% or more, more preferably 35 vol% or more, particularly preferably 40 vol% or more, based on the total volume of the starting material.

18. Use according to claim 16 or 17, characterized in that the sintered material is selected from the group comprising titanium dioxide, zirconium oxide, silicon carbide, aluminum oxide, aluminum hydroxide and mixtures thereof.

19. Use according to any one of claims 16 to 18, characterized in that the resin composition comprises at least two thermosetting resins and at least one hardener.

20. Use according to any one of claims 16 to 19, characterized in that the starting material comprises a black pigment.

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