Amorphous silicon dioxide in a building material for improving the reusability of the building material

Abstract

The invention relates to a process for preparing an aged building material from a process for additively manufacturing a three-dimensional object, wherein the preparation process comprises: mixing i) an aged building material from a process for additively manufacturing a three-dimensional object, wherein: the process for additively manufacturing a three-dimensional object comprises providing a building material layer by layer and selectively solidifying the building material layer by layer by the action of electromagnetic radiation, emitted by a radiation source, at positions in each layer that correspond to the cross section of the object in this layer; and the non-solidified building material is detached and forms the aged building material, and ii) a fresh building material for additively manufacturing a three-dimensional object, wherein: a prepared building material for additively manufacturing a three-dimensional object is formed; the aged building material and the fresh building material each contain a polymer and at least the fresh building material contains an amorphous silicon dioxide; and the ratio based on percent by weight of aged building material to fresh building material is greater than 60:40.

Description

[0001] EOS GmbH Electro Optical Systems September 12, 2025

[0002] M / EOSG-072-PC

[0003] Amorphous silicon dioxide in a build-up material to improve the reusability of the build-up material.

[0004] Description

[0005] The invention relates to a method for processing aged build material from a method for the additive manufacturing of a three-dimensional object. The invention further relates to a method for manufacturing a three-dimensional object. The invention further relates to the use of amorphous silicon dioxide in a build material to improve the reusability of the build material in a method for the additive manufacturing of a three-dimensional object. The invention also relates to a mixture comprising i) aged build material from a method for the additive manufacturing of a three-dimensional object and ii) fresh build material for the additive manufacturing of a three-dimensional object.

[0006] Methods for the additive manufacturing of three-dimensional objects are becoming increasingly important. Such a method involves providing a build material layer by layer and selectively solidifying the build material layer by layer by applying electromagnetic radiation, emitted by a radiation source, to positions in each layer that correspond to the cross-section of the object in that layer.

[0007] A polymer, such as a polyamide, can serve as the building material. In addition to the polymer, the building material often contains one or more additives.

[0008] Build material that does not solidify during the process and therefore does not form part of the three-dimensional object is separated during the additive manufacturing of three-dimensional objects. Compared to fresh build material—that is, build material that has not yet been used in an additive manufacturing process—this build material exhibits signs of aging and is also referred to as aged build material. For example, the polymer chains of the build material can elongate due to the temperature during the additive manufacturing process. Meissner Bolte M / EOSG-072-PC 2

[0009] For ecological and economic reasons, the reusability and reuse of materials are also becoming increasingly important.

[0010] Therefore, additive manufacturing processes for three-dimensional objects also use mixtures of aged and fresh build material. For example, aged build material from an additive manufacturing process for a three-dimensional object is reprocessed by mixing it with fresh build material. This reprocessing is also called refreshing. So far, the ratio of aged to fresh build material by weight has been a maximum of 60:40. If a larger proportion of aged build material is used, defects occur in the manufacturing process and / or in the three-dimensional object when using conventional build material in the additive manufacturing process.

[0011] Existing build materials, existing processes for reprocessing aged build materials from additive manufacturing processes for three-dimensional objects, and existing processes for manufacturing three-dimensional objects still offer potential for improvement in terms of product quality, efficiency, costs, energy savings, resource conservation, reusability, and waste reduction. In particular, there is a desire to increase the ratio of aged to fresh build material during the refinishing process.

[0012] Against this background, one object of the present invention is to provide an improved method for preparing an aged build-up material from a method for additively manufacturing a three-dimensional object and an improved method for manufacturing a three-dimensional object.

[0013] Summary of the invention

[0014] The efforts to solve this problem have resulted, in a first aspect, in a method for processing an aged build material from a method for the additive manufacturing of a three-dimensional object, whereby the processing method involves mixing of

[0015] i) an aged build material from a process for the additive manufacturing of a three-dimensional object, wherein the process for the additive manufacturing of a three-dimensional object involves providing a build material layer by layer Meissner Bolte M / EOSG-072-PC 3

[0016] and comprising selectively solidifying the build material layer by layer by applying electromagnetic radiation emitted from a radiation source to positions in each layer corresponding to the cross-section of the object in that layer, wherein the build material that is not solidified is separated and forms the aged build material, and

[0017] ii) a fresh build-up material for the additive manufacturing of a three-dimensional object,

[0018] includes, whereby a processed build-up material is formed for the additive manufacturing of a three-dimensional object,

[0019] wherein the aged build-up material and the fresh build-up material each contain a polymer and wherein at least the fresh build-up material contains an amorphous silicon dioxide, wherein the ratio based on weight percent of aged build-up material to fresh build-up material is greater than 60:40.

[0020] Furthermore, the efforts to solve the aforementioned task result, in a second aspect, in a method for producing a three-dimensional object, comprising

[0021] a) the process for processing according to the first aspect and

[0022] b) the provision of the prepared build material, wherein the provision is carried out layer by layer, and the selective solidification of the build material layer by layer by the action of electromagnetic radiation emitted from a radiation source at positions in each layer corresponding to the cross-section of the object in that layer. The process can also be referred to as a method for the additive manufacturing of a three-dimensional object or as an additive manufacturing process.

[0023] A further aspect of the efforts to solve the aforementioned problem is the use of amorphous silicon dioxide in a build-up material to improve the reusability of the build-up material in a process for the additive manufacturing of a three-dimensional object.

[0024] It was found that amorphous silicon dioxide in a build-up material surprisingly improves its properties, particularly its reusability in an additive manufacturing process for three-dimensional objects. For example, the use of amorphous silicon dioxide in the build-up material can increase the ratio, by weight percent, of aged build-up material to fresh build-up material to greater than 60:40 (Meissner Bolte M / EOSG-072-PC 4).

[0025] This is particularly advantageous because amorphous silicon dioxide can also serve, or does serve, as a flow aid in the building material.

[0026] In a fourth aspect, the invention relates to a mixture comprising i) an aged build-up material from a method for additively manufacturing a three-dimensional object, wherein the method for additively manufacturing a three-dimensional object comprises providing a build-up material layer by layer and selectively solidifying the build-up material layer by layer by applying electromagnetic radiation emitted by a radiation source at positions in each layer corresponding to the cross-section of the object in that layer, wherein the build-up material that is not solidified is separated and forms the aged build-up material, and

[0027] ii) a fresh build-up material for the additive manufacturing of a three-dimensional object,

[0028] wherein the aged build-up material and the fresh build-up material each contain a polymer and wherein at least the fresh build-up material contains an amorphous silicon dioxide,

[0029] where the ratio, based on weight percent of aged building material to fresh building material, is greater than 60:40.

[0030] In a fifth aspect, the invention relates to a three-dimensional object, wherein the object is obtainable by a method according to the invention.

[0031] In a sixth aspect, the invention relates to a processed build-up material for the additive manufacturing of a three-dimensional object, wherein the processed build-up material is obtainable by a method according to the invention.

[0032] Detailed description of the invention

[0033] According to the invention, a method for processing aged build material from a method for the additive manufacturing of a three-dimensional object is provided. In other words, the aged build material originates from a method for the additive manufacturing of a three-dimensional object. As described above, aged build material exhibits signs of aging compared to fresh build material, i.e., build material that has not yet been used in a method for the additive manufacturing of three-dimensional objects. In other words, aged build material and fresh build material differ in that the aged build material originates from a method for the additive manufacturing of three-dimensional objects. Meissner Bolte M / EOSG-072-PC 5

[0034] was used and the fresh build-up material was not used in a process for the additive manufacturing of three-dimensional objects.

[0035] The build-up material is preferably in powder form. This applies to fresh, aged, and processed build-up material. Selective solidification of the build-up material comprises melting it through exposure to electromagnetic radiation, followed by solidification and / or recrystallization of the build-up material as a component of the three-dimensional object.

[0036] In a preferred embodiment, the aged build-up material and the fresh build-up material contain the same polymer.

[0037] In a preferred embodiment, the polymer comprises a polyamide. In a preferred embodiment, the polymer is a polyamide. A polyamide selected from polyamide 12, polyamide 11, polyamide 6, and mixtures thereof is preferred. It has been found that amorphous silicon dioxide, particularly in a build-up material containing polyamide, surprisingly improves the reusability of the build-up material in a process for the additive manufacturing of a three-dimensional object.

[0038] According to a preferred embodiment of the method for manufacturing a three-dimensional object, build material that does not solidify during the process and thus does not form part of the three-dimensional object is separated during the additive manufacturing of the three-dimensional object. In a preferred embodiment, the separated build material is processed as aged build material in a method according to the invention. In a preferred embodiment, the processed build material is used in a method for the additive manufacturing of a three-dimensional object. Such a method can represent a closed loop, thereby reducing resource and energy consumption as well as waste volumes. The separated and aged build material can thus be reused multiple times.

[0039] The invention enables improved reusability of the build-up material. In other words, the inventive method and use are characterized by improved reusability of the build-up material. Improved reusability is characterized by a ratio, based on weight percent, of aged build-up material to fresh build-up material that is greater than 60:40. For example, the Meissner Bolte M / EOSG-072-PC 6

[0040] The ratio of aged to fresh material by weight should be greater than 60:40 but no more than 80:20. In a preferred embodiment, the ratio of aged to fresh material by weight should be between 65:35 and 80:20. In a further preferred embodiment, the ratio of aged to fresh material by weight should be between 65:35 and 75:25.

[0041] The improved reusability according to the invention is also characterized by the fact that a continuous process can be operated, in particular a continuous circular process. For example, the process according to the invention can be designed such that the process according to the second aspect comprises separating build-up material that does not solidify, processing the separated, aged build-up material, and using the processed build-up material in a process for the additive manufacturing of a three-dimensional object.According to the invention, such a method can be operated in which at least two, preferably at least three, more preferably at least four, and even more preferably at least five successive processes for the additive manufacturing of a three-dimensional object according to the second aspect are carried out, wherein the ratio based on weight percent of aged build-up material to fresh build-up material is in each case greater than 60:40, without the manufactured three-dimensional objects having a defect with respect to at least one parameter selected from surface defect-freeness, tensile strength, elongation at break and modulus of elasticity and / or without disturbances occurring in the additive manufacturing process (for example, adhesions during coating).

[0042] In preferred embodiments, the amorphous silicon dioxide is a pyrogenic silica. The amorphous silicon dioxide preferably has a hydrophobic surface. In particular, in preferred embodiments, the amorphous silicon dioxide can have a surface modification with dimethyldichlorosilane. It has been found that particularly good results can be achieved with amorphous silicon dioxide with a corresponding hydrophobic surface with regard to the reusability of the build material and with regard to at least one parameter selected from surface defect freedom, tensile strength, elongation at break, and modulus of elasticity of three-dimensional objects produced.

[0043] Preferably, the amorphous silicon dioxide has a BET surface area between 75 m². 2 / g and 190 m 2 / g, preferably from at least 80 m 2 / g and / or at most 160 m 2 / g, Meissner Bolte M / EOSG-072-PC 7

[0044] especially preferred from at least 90 m 2 / g and / or at most 140 m 2 / g, on. The BET surface can be determined, for example, according to DIN EN ISO 9277. It has been found that particularly good results can be achieved with amorphous silicon dioxide with a corresponding BET surface regarding the reusability of the build material and with regard to at least one parameter selected from surface defect freedom, tensile strength, elongation at break, and modulus of elasticity of manufactured three-dimensional objects.

[0045] Preferably, the amorphous silicon dioxide has a mean particle size between 1 nm and 50 nm, preferably at least 5 nm and / or at most 35 nm, and particularly preferably at least 10 nm and / or at most 20 nm. The mean particle size is preferably the mean particle size d50. The particle size can be determined according to ISO 13320-1 (wet), e.g., using a CILAS 1064 laser diffraction meter. It has been found that particularly good results can be achieved with amorphous silicon dioxide with a corresponding mean particle size with regard to the reusability of the build material and with regard to at least one parameter selected from surface defect freedom, tensile strength, elongation at break, and Young's modulus of three-dimensional objects produced.

[0046] In preferred embodiments, at least the fresh build-up material contains at least 0.01 wt.% to at most 0.5 wt.% of amorphous silicon dioxide. Preferably, at least the fresh build-up material contains at least 0.02 wt.% or at least 0.03 wt.% of amorphous silicon dioxide. Preferably, at least the fresh build-up material contains at most 0.3 wt.% or at most 0.1 wt.% of amorphous silicon dioxide.

[0047] In preferred embodiments, the aged build material and / or the processed build material also contains at least 0.01 wt.% to 0.5 wt.% of amorphous silicon dioxide. Preferably, the aged build material and / or the processed build material also contains at least 0.02 wt.% or at least 0.03 wt.% of amorphous silicon dioxide. Preferably, the aged build material and / or the processed build material also contains at most 0.3 wt.% or at most 0.1 wt.% of amorphous silicon dioxide.

[0048] It was found that particularly good results with amorphous silicon dioxide in appropriate quantities were achieved with regard to the processability and reusability of the build-up material, as well as with regard to at least one parameter selected from Meissner Bolte M / EOSG-072-PC 8.

[0049] Surface defect-free surfaces, tensile strength, elongation at break and modulus of elasticity of manufactured three-dimensional objects can be achieved.

[0050] In a preferred embodiment, the amorphous silicon dioxide increases the recrystallization temperature of the build material by at most 4 °C, more preferably by at most 3 °C, even more preferably by at most 2 °C, and most preferably by at most 1 °C, compared to the build material without the amorphous silicon dioxide. In other words, the onset of recrystallization upon cooling of the build material is at most 4 °C, more preferably by at most 3 °C, even more preferably by at most 2 °C, and most preferably by at most 1 °C higher than that of the build material and / or the pure polymer without the amorphous silicon dioxide. The recrystallization temperature can be determined by differential scanning calorimetry, for example, according to DIN EN ISO 11357-3:2018-07. It has been found that amorphous silicon dioxide increases the recrystallization temperature only slightly, which is advantageous for the processability of the build material by additive manufacturing.a. because the sintering window is preserved.

[0051] In a preferred embodiment, the use is such that a three-dimensional object additively manufactured from the build-up material exhibits an improvement over an additively manufactured three-dimensional reference object with respect to at least one parameter selected from surface defect-free properties, tensile strength, elongation at break, and modulus of elasticity, wherein both objects are manufactured by a method for additively manufacturing a three-dimensional object, the method comprising providing a build-up material layer by layer and selectively solidifying the build-up material layer by layer by applying electromagnetic radiation emitted by a radiation source at positions in each layer corresponding to the cross-section of the object in that layer, wherein the method for manufacturing the three-dimensional object differs from the method for manufacturing the reference object in thatthat the build-up material for producing the comparison object does not contain the amorphous silicon dioxide, wherein the build-up material is in each case a mixture comprising i) an aged build-up material from a method for additively manufacturing a three-dimensional object, wherein the method for additively manufacturing a three-dimensional object comprises providing a build-up material layer by layer and selectively solidifying the build-up material layer by layer by applying electromagnetic radiation emitted from a radiation source at positions in each layer corresponding to the cross-section of the object in Meissner Bolte M / EOSG-072-PC 9,

[0052] This layer comprises, wherein the unconsolidated structural material is separated and forms the aged structural material, and

[0053] ii) a fresh build-up material for the additive manufacturing of a three-dimensional object,

[0054] wherein the aged build-up material and the fresh build-up material each contain a polymer and optionally wherein at least the fresh build-up material contains an amorphous silicon dioxide, wherein the ratio based on weight percent of aged build-up material to fresh build-up material is greater than 60:40.

[0055] The embodiments and aspects within this document may be combined arbitrarily, unless the subject matter and the description of the embodiments and aspects clearly indicate otherwise. Preferred embodiments are also listed in the claims.

[0056] The verbs “contain” and “encompass” and their conjugations also include the verb “consist of” with its conjugations.

[0057] The terms “ein” and “eine” do not represent a numerical limit, but are to be understood as “at least one” and “at least one”, unless the context clearly indicates otherwise.

[0058] The invention is illustrated below by means of examples and with reference to Figures 1-4, the examples and figures being non-limiting. In a comparative example, the powdered build-up material 0 was used. This is polyamide 12 with 0.05 wt% of a conventional flow agent. First, the powdered build-up materials 1-5 were prepared. For this purpose, powdered polyamide 12 was mixed with various types of powdered amorphous silicon dioxide. An overview of the build-up materials 0-5 and the properties of the amorphous silicon dioxide used is shown in Table 1:

[0059]

[0060] Meissner Bolte M / EOSG-072-PC io

[0061]

[0062] Table 1.

[0063] The recrystallization temperature was determined using differential scanning calorimetry according to DIN EN ISO 11357-3:2018-07 on fresh build-up material 1-3. Only a slight increase due to the amorphous silicon dioxide was observed. The results are shown in Table 1 and Fig. 1. For pure polyamide 12, recrystallization began at 147.7 °C. No or only a slight change in the recrystallization temperature is advantageous to maintain a sufficiently large sintering window.

[0064] The flow behavior of fresh build-up material 1-3 at room temperature was measured by determining the avalanche angle. This was performed on fresh powder and after successive cycles, each comprising an additive manufacturing process and a refreshing of the aged build-up material. Thus, the fresh build-up material and the processed build-up material after the 1st, 2nd, 3rd, 4th, and 5th refreshing were analyzed. The results are shown in Fig. 2. The larger the avalanche angle, the poorer the flowability.

[0065] The compressibility of fresh build-up material 1-3 was further determined using the following procedure: The powder was sheared at a specific height with a test glass to create a flat and homogeneous powder surface. Subsequently, a ram exerted a normal force on the powder surface, compressing the powder. This process was carried out in 10 steps, starting with an initial force of 0.5 kPa and increasing to a maximum normal force of 18 kPa. The results of this method include the "conditioned bulk density" of Meissner Bolte M / EOSG-072-PC 11.

[0066] The powder and its "compressibility at 18 kPa," defined as the degree of compaction of the powder at 18 kPa and expressed as a percentage change in volume, were measured. The procedure was performed on fresh powder as well as on the processed build-up material after the 1st, 2nd, 3rd, 4th, and 5th refreshing stages. The result is shown in Fig. 3.

[0067] Fig. 4 is a schematic overview of a use according to the invention and of a method 10 according to the invention, comprising an additive manufacturing 12 of a three-dimensional object 13, a processing 15 of aged build material 14 and a further additive manufacturing process 12. The invention is not limited to this, however, but can also comprise only the processing 15 or a process with several cycles, each comprising an additive manufacturing process 12 and a processing 15.

[0068] The powdered build materials 0-5 are each used as fresh build material 11 in an additive manufacturing process 12 to produce a three-dimensional object 13. In other words, the corresponding fresh build material 11 is provided layer by layer and selectively solidified layer by layer by the action of electromagnetic radiation emitted from a radiation source at positions in each layer that correspond to the cross-section of the object 13 in that layer.

[0069] Build material 14, which does not solidify and therefore does not form part of the additively manufactured, three-dimensional object 13, is separated. Since the material 14 exhibits altered properties due to the thermal stress in the preceding additive manufacturing process 12, it is considered aged and must be reprocessed for reuse. Reprocessing 15 is carried out by mixing the aged build material 14 with fresh build material 11 in a ratio of 70:30 (based on the weight percentage of aged build material 14 to fresh build material 11). The aged build material 14 is mixed with the corresponding fresh build material 11 (i.e., aged build material 0 with fresh build material 0, aged build material 1 with fresh build material 1, aged build material 2 with fresh build material 2, etc.). This yields reprocessed build material.

[0070] The appropriately prepared build material is then used again in an additive manufacturing process 12 to produce a three-dimensional object 13. Build material 14, which is not solidified and therefore does not form part of Meissner Bolte M / EOSG-072-PC 12

[0071] The material formed from the additively manufactured, three-dimensional object 13 is separated again, processed and fed back into the additive manufacturing process 12.

[0072] To test the robustness of the process over several cycles (each comprising an additive manufacturing step 12 and a refreshing step 15), the process shown in Fig. 4 was continued, as indicated by the dashed arrow. First, a three-dimensional component 13 was produced from 100% fresh build material 0-5. This was followed by five cycles, each comprising a reprocessing step 15 ("refreshing") of the aged build material 14 with the corresponding fresh build material 11, as well as an additive manufacturing step 12.

[0073] The additive manufacturing processes 12 were each carried out in the same manner, with the aim that all manufactured or to be manufactured objects 13 have the same three-dimensional shape. Among other things, distortion frames and components were manufactured in accordance with DIN EN ISO 527-2:2012-06 (test specimens 1A and 1B).

[0074] The manufactured objects were examined for surface defects. The results are shown in Table 2:

[0075]

[0076] Table 2.

[0077] The experiment shows that the build-up material with amorphous silicon dioxide can be repeatedly refreshed with fresh build-up material at a ratio (by weight percent) of aged build-up material to fresh build-up material greater than 60:40 and reused in additive manufacturing processes without surface defects occurring. Build-up materials 1 and 5 were particularly advantageous in this regard. Refreshing build-up material 0 with a ratio of aged build-up material to fresh build-up material greater than 60:40 (by weight percent) was unsuccessful.

[0078] Reference symbol list

[0079] 10. Inventive method

[0080] 11 Fresh assembly material Meissner Bolte M / EOSG-072-PC

[0081] 13

[0082] 12 Additive manufacturing of a three-dimensional object 13 Three-dimensional object

[0083] 14 Aged building material

[0084] 15. Reprocessing the aged building material

Claims

Meissner Bolte M / EOSG-072-PC 14 Claims 1. Method for processing an aged build material from a method for additively manufacturing a three-dimensional object, wherein the processing method comprises: Mixing (i) an aged build-up material from a method for additively manufacturing a three-dimensional object, wherein the method for additively manufacturing a three-dimensional object comprises providing a build-up material layer by layer and selectively solidifying the build-up material layer by layer by applying electromagnetic radiation emitted from a radiation source at positions in each layer corresponding to the cross-section of the object in that layer, wherein the build-up material that is not solidified is separated and forms the aged build-up material, and ii) a fresh build-up material for the additive manufacturing of a three-dimensional object, wherein a processed build material is formed for the additive manufacturing of a three-dimensional object, wherein the aged build-up material and the fresh build-up material each contain a polymer and wherein at least the fresh build-up material contains an amorphous silicon dioxide, wherein the ratio based on weight percent of aged build-up material to fresh build-up material is greater than 60:

40.

2. Method for producing a three-dimensional object, comprising a) the process for processing according to the preceding claim and b) the provision of the prepared build material, wherein the provision is carried out layer by layer, and the selective solidification of the build material layer by layer by the action of electromagnetic radiation emitted from a radiation source at positions in each layer corresponding to the cross-section of the object in that layer.

3. Method according to the previous claim, characterized by the fact that the building material that is not solidified is separated and used as aged building material in a process according to one of the preceding claims Meissner Bolte M / EOSG-072-PC 15 is processed and optionally used in a process for the additive manufacturing of a three-dimensional object.

4. Method according to any of the preceding claims, characterized by the fact that The ratio, based on weight percent of aged building material to fresh building material, is between 65:35 and 80:

20.

5. Method according to any of the preceding claims, characterized by the fact that amorphous silicon dioxide has a hydrophobic surface.

6. Method according to any of the preceding claims, characterized by the fact that the amorphous silicon dioxide has a surface modification with dimethyldichlorosilane.

7. Method according to any of the preceding claims, characterized by the fact that the amorphous silicon dioxide has a BET surface area between 75 m 2 / g and 190 m 2 / g, preferably from at least 80 m 2 / g and / or at most 160 m 2 / g, particularly preferably of at least 90 m 2 / g and / or at most 140 m 2 / g, exhibits.

8. Method according to any of the preceding claims, characterized by the fact that the amorphous silicon dioxide has a mean particle size between 1 nm and 50 nm, preferably at least 5 nm and / or at most 35 nm, particularly preferably at least 10 nm and / or at most 20 nm.

9. Method according to any of the preceding claims, characterized by the fact that at least the fresh build-up material contains at least 0.01 wt.% to 0.5 wt.%, preferably at least 0.02 wt.% and / or at most 0.3 wt.%, particularly preferably at least 0.03 wt.% and / or at most 0.1 wt.%, of amorphous silicon dioxide.

10. Method according to any of the preceding claims, Meissner Bolte M / EOSG-072-PC 16 characterized by the fact that The aged building material and the fresh building material contain the same polymer.

11. Method according to any of the preceding claims, characterized by the fact that the polymer comprises a polyamide, preferably a polyamide selected from polyamide 12, polyamide 11, polyamide 6 and mixtures thereof.

12. Use of amorphous silicon dioxide in a build-up material to improve the reusability of the build-up material in a process for the additive manufacturing of a three-dimensional object.

13. Use according to the previous claim, characterized by the fact that The amorphous silicon dioxide increases the recrystallization temperature of the build material by a maximum of 4 °C.

14. Use according to any of the preceding claims, characterized by the fact that A three-dimensional object additively manufactured from the build-up material exhibits an improvement over an additively manufactured three-dimensional reference object with respect to at least one parameter selected from surface defect freedom, tensile strength, elongation at break, and Young's modulus, wherein both objects are manufactured by a method for additively manufacturing a three-dimensional object, the method comprising providing a build-up material layer by layer and selectively solidifying the build-up material layer by layer by applying electromagnetic radiation emitted by a radiation source at positions in each layer corresponding to the cross-section of the object in that layer, wherein the method for manufacturing the three-dimensional object differs from the method for manufacturing the reference object in thatthat the build-up material for producing the comparison object does not contain amorphous silicon dioxide, wherein the build-up material is in each case a mixture comprising, i) an aged build-up material from a process for the additive manufacturing of a three-dimensional object, wherein the process for the additive manufacturing of a three-dimensional object involves providing a build-up material layer Meissner Bolte M / EOSG-072-PC 17 for layer and selective solidification of the build-up material layer by layer by the action of electromagnetic radiation emitted from a radiation source at positions in each layer corresponding to the cross-section of the object in that layer, wherein the build-up material that is not solidified is separated and forms the aged build-up material, and ii) a fresh build-up material for the additive manufacturing of a three-dimensional object, wherein the aged build-up material and the fresh build-up material each contain a polymer and optionally wherein at least the fresh build-up material contains an amorphous silicon dioxide, wherein the ratio based on weight percent of aged build-up material to fresh build-up material is greater than 60:

40.

15. Mixture, comprehensive (i) an aged build-up material from a method for additively manufacturing a three-dimensional object, wherein the method for additively manufacturing a three-dimensional object comprises providing a build-up material layer by layer and selectively solidifying the build-up material layer by layer by applying electromagnetic radiation emitted from a radiation source at positions in each layer corresponding to the cross-section of the object in that layer, wherein the build-up material that is not solidified is separated and forms the aged build-up material, and ii) a fresh build-up material for the additive manufacturing of a three-dimensional object, wherein the aged build-up material and the fresh build-up material each contain a polymer and wherein at least the fresh build-up material contains an amorphous silicon dioxide, where the ratio, based on weight percent of aged building material to fresh building material, is greater than 60:40.

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