Material for selective laser sintering and laser sintering using such material

Abstract

To propose a powder for use in a powder bed fusion bonding method, such as a selective laser sintering (SLS) method.SOLUTION: There is provided a method for preparing a molded article in a layer-by-layer process in which an area of a powdered layer is selectively melted, sintered, fused or otherwise solidified. The method is characterized in that: a thermoplastic ground polyamide powder is used as a powder for the powdered layer; the polyamide contains laurolactam and caprolactam, preferably exclusively contains them; and a proportion of caprolactam falls within a range of 40 to 60 mol% of lactams to be used.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to materials used in powder bed fusion (PBF) technology, such as selective laser sintering (SLS), as well as methods for producing such materials, selective PBF processes using such materials, such as laser sintering processes, and articles prepared by an SLS process using these materials. [Background technology]

[0002] Powder bed fusion (PBF) technology is an additive manufacturing process that produces spatial structures by sintering powder starting materials using a laser. In this process, loose, unlayered powder is placed in a container, and the processed product is continuously layered by selective irradiation from above using a laser, which irradiates only the areas to be solidified, causing the material to melt and solidify. After the irradiation of a layer, and its liquefaction and / or solidification, a subsequent layer made of the powder starting materials is spread on top, and in the next step, a desired area of ​​this next layer is melted, solidified if necessary, and simultaneously fused with the molten or already solidified layer below. Specifically, to prepare a molded part, polymer powder is applied in a thin layer to a lowered plate in a sintering chamber, which is typically heated to a temperature slightly below the polymer's melting point. The layer thickness is selected so that a molten layer is formed during or after the subsequent laser sintering. According to the specifications of the control computer, a laser sintersects the powder particles. The plate is then lowered by the amount of the layer thickness, typically 0.05 to 2.0 mm. A new powder layer is applied, and the process is repeated. After completion of a pre-selected number of cycles according to the intended number of layers, a block consisting of powder is formed externally. Internally, it encases a block of highly viscous molten or already largely solidified material in the shape of the desired molded part. The non-molten regions, where the powder remains in solid form, stabilize the shape of the molten material. The block, consisting of the powder shell and molten material, is then slowly cooled, and the molten material solidifies when it falls below the polymer's solidification temperature. It is advantageous if the block is kept at the solidification temperature until the phase transformation is complete. This is achieved by selecting a slow cooling rate within the phase transformation temperature range, thereby keeping the internal molded body at just the solidification temperature until the phase transformation is complete. After cooling, the block is removed from the sintering chamber, and the molded body is separated from the unsolidified polymer powder. The powder can be reused in the process.

[0003] As described in DE19747309, commonly used polymers powdered for such processes include not only polyamide 11 (PA11) or polyamide 12 (PA12), and polyamide 6 (PA6), but also polyacetal, polypropylene (PP), polyethylene (PE), and ionomers. Polycarbonate (PC) and polystyrene (PS) have also been used. EP1720930 relates to copolymer powders, the use of these powders for a non-centralized molding process, and molded articles made from these polymer powders. The molding process is a layer-by-layer process using the powder, thereby selectively melting regions of each layer by the non-centralized introduction of electromagnetic energy. Selectivity can be achieved by masking, imparting inhibitors, absorbers, and susceptors. Molded articles made from powders according to the above process can vary over a wide range in terms of component properties, particularly mechanical and thermal component properties, compared to molded articles made from conventional powders, depending on the composition. The PA6 / 12 / 66 structure system is efficiently produced, and MVR values ​​in the range of 1 to 12 g / min have been shown. EP2274363 relates to a method for lowering the crystallization and melting temperatures of a polyamide powder obtained from the polymerization of at least one main monomer, wherein the reduction in crystallization temperature is greater than the reduction in the melting temperature process, and the method comprises a polymerization step of at least one majority monomer and at least one small number of different comonomers based on a similar polymerization method, wherein at least one small number of comonomers is selected from aminocarboxylic acids, diamine-dibasic acid pairs, lactams, and / or lactones, and at least one less comonomer corresponds to 0.1 to 20% by mass of the total mixture of monomers and comonomers, preferably 0.5 to 15% by mass of the total mixture, preferably 1 to 10% by mass of the total mixture. A PA12 / 6 type system is used, and therefore the proportion of caprolactam should not exceed 20%.

[0004] WO-A-2011124278 relates to a polymer powder used in a layer-by-layer process in which regions of each powder layer are selectively fused by introducing electromagnetic energy. The polymer powder comprises at least one AB-type polyamide prepared by polymerization of a lactam having 10 to 12 carbon atoms in monomer units, or by polycondensation of a corresponding aminocarboxylic acid having 10 to 12 carbon atoms in monomer units, and at least one AABB-type polyamide prepared by polycondensation of a diamine and a dicarboxylic acid, each having 10 to 14 carbon atoms in monomer units, wherein the AB-type polyamide contains up to 20 mol% AABB comonomer units, and the AABB-type polyamide contains up to 20 mol% AB monomer units. The invention also relates to a process for preparing such a powder, and a layer-by-layer process for producing a molded article from such a powder in which regions of each layer are selectively melted by introducing electromagnetic energy, wherein selectivity is achieved by using a mask, or by imparting an inhibitor, absorbent or susceptor, or by concentrating the imparted energy, thereby preparing a molded article.

[0005] WO-A-2015009790 describes a component material for printing three-dimensional parts using an electrophotographic additive manufacturing system, wherein the component material comprises a composition having a semi-crystalline thermoplastic material and a charge control agent. The component material is supplied in the form of a powder with controlled particle size and is configured for use in an electrophotographic additive manufacturing system having a layer injection configuration for printing three-dimensional parts layer by layer. Different materials for the powder used are mentioned, but no specific system is described. WO-A-2020064825 relates to a sintered powder comprising a first polyamide component and a second polyamide component, wherein the melting point of the second polyamide component is higher than the melting point of the first polyamide component. The invention further relates to a method for preparing a molded article by sintering or an FFF process (fusible filament manufacturing method) of the sintered powder, and to a molded article obtained by the method of the invention. The invention further relates to a process for preparing the sintered powder. A mixture of aliphatic polyamide and semi-aromatic polyamide is used, and therefore polyamide 6 and polyamide 66 are used as aliphatic polyamides.

[0006] CN-A-107337793 describes copolymer nylon powder used in selective laser sintering and a process for producing the same. The method includes the following steps: a step of copolymerizing short-chain nylon raw materials and long-chain nylon raw materials using the copolymerization reaction principle to obtain a copolymer nylon resin; a step of low-temperature crushing, drying, and sieving of the copolymer nylon resin; and a step of adding a flow aid and an antioxidant to obtain a copolymer nylon powder material used in selective laser sintering. Systems based on polyamide 1010 and polyamide 1212 or polyamide 66 are used. CN-A-104830053 relates to the field of polymer materials and aims to solve the problem of the high industrial cost of nylon 12 in the field of 3D printing. The above invention discloses a caprolactam-laurolactam copolymer modified with glass fibers and a method for preparing its powder, and the relative mechanical properties of the obtained polymer are described as follows: tensile strength of 50-65 MPa, elongation at break of 50-300%, and water absorption of 2.3-0.4%. The powder has a particle size of 10-80 [mu] m. No toxic or harmful substances, such as wastewater and exhaust gases, are generated throughout the preparation process. The above preparation method requires a short reaction time, has a high conversion rate, stable molecular weight, and low cost. The above copolymer powder has excellent performance, such as thermodynamic properties and size stability, low manufacturing and usage costs, and uniform particle size, and can be used to partially replace nylon 12, particularly in the field of 3D printing.

[0007] WO2005082979 relates to polymer powders containing copolymers, the use of such powders in a molding method, and molded articles produced from such polymer powders. The molding method involves working layer by layer with the powder, during which each layer is fused by the concentrated application of electromagnetic energy. Selectivity of energy application can be achieved by focusing a laser beam through a suitable lens or through a suitable tube, cable, or optical fiber, but the invention is not limited to the use of these materials. Furthermore, it can also be focused using a suitable mirror or lens. Once cooled, the solidified molded article can be removed from the powder bed. The component properties, particularly the mechanical and thermal component properties, of molded articles produced using the powder of the invention according to the method of the invention can vary over a wide range depending on their composition compared to molded articles produced from conventional powders. In particular for amorphous copolymers, the flow behavior in the molding method can be optimized by the skilled selection of comonomers. A further advantage is that the clever composition of the copolymers also simplifies processing. Processing can be performed at low temperatures, which simplifies temperature control and accelerates the processing. The slower crystallization of semicrystalline polymers compared to semicrystalline homopolymers promotes the coalescence of fused particles, resulting in improved shrinkage behavior in molded articles. US-B-8097333 provides a pre-impregnated composite material (prepreg) that can be cured to form composite parts with a high level of damage resistance. The matrix resin contains a thermoplastic particle component which is a blend of particles having a melting point higher than the curing temperature and particles having a melting point at or below the curing temperature. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] DE19747309 [Patent Document 2] EP1720930

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

Summary of the Invention

[0009] The object of the present invention is to propose a powder used in a powder bed fusion bonding method, for example, an SLS method of the type described above. The powder bed fusion bonding method can include selectively fusing, melting, sintering, or solidifying a powder material using a concentrated or non-concentrated input of electromagnetic energy, thermal energy, or other energy in an additive manufacturing process. Preferably, the powder is for the manufacture of an article / molded product in a layer-by-layer process in which regions of a powder layer are selectively melted by a concentrated or non-concentrated input of electromagnetic energy. It can be used not only in the SLS process but also in the multi-jet fusion (MJF) process, the selective absorption fusion (SAF) process, or the high-speed sintering (HSS) process.

[0010] Specifically, a powder having at least one of the following advantageous properties is provided. · Wide range of mechanical and physical properties similar to those of conventional PP-based and PA11-based ones, · Lower operating temperature (increased process speed) with an increased amount of laurolactam, accompanied by a shortened cooling time and increased recyclability of the product, without significantly changing the impact strength of the material, · A polyamide having material properties with reduced shrinkage in the Z direction, which is in contrast to the current market level, and having excellent properties, with or without such reduced shrinkage, · A reduction in manufacturing cost compared to PA11 materials, · The possibility of dry mixing a colorant into the material for printing a fully colored portion where the colorant does not bleed out.

[0011] The powder according to the present invention is defined as a solid substance (at room temperature) that has been broken into fine, discrete particles, for example, by crushing, grinding, disintegration, precipitation, or a combination thereof. According to a first aspect of the present invention, the present invention relates to a powder of a copolyamide for the preparation of a molded article in a layer process, and optionally, the region of the powder layer (1) is melted by the input of electromagnetic energy (typically by a controlled laser), (2) is melted by the input of thermal energy from a source other than electromagnetic energy, or (3) otherwise is melted, fused, sintered, or solidified to form an article or object, relates to the powder.

[0012] Such a powder is, according to claim 1, a thermoplastic powder for the powder layer, preferably a ground polyamide powder is used, and the polyamide is composed of laurolactam (Lc12) and caprolactam (Lc6), that is, consists of these, and the proportion of laurolactam is 40 - 60 mol% of the lactams used, which is characterized. Therefore, the above powder contains, or consists of, a thermoplastic ground polyamide powder in which the polyamide contains or consists of laurolactam and caprolactam, and the proportion of caprolactam is 40 - 60 mol% of the lactams used. In fact, when the above thermoplastic polyamide powder is based on a powder consisting of laurolactam (Lc12) and caprolactam (Lc6), it has been shown that the above-mentioned advantages can be surprisingly achieved.

[0013] The powder for a layer-by-layer process, preferably in which regions of the powder layer are selectively melted, sintered, fused, or solidified by concentrated or non-concentrated input of electromagnetic energy, may consist solely of the thermoplastic polyamide powder, or it may be a mixture of thermoplastic polyamide powder with other powder materials. The proportion of the thermoplastic polyamide powder in such a mixture is typically at least 50% by mass, preferably at least 60% by mass, or as further detailed below, relative to the total amount of the powders. The powder materials different from the thermoplastic polyamide may include, for example, powder particles consisting of filler materials (organic or inorganic), flow aid materials, stabilizer materials (including thermal stabilization and optical stabilization), colorants including pigments or dyes, or combinations thereof, in the form of individual particles or particles in a mixture of such materials. Preferably, the particle size of such different powder particles is selected within a range similar to, or essentially similar to, that further defined below for the powder particles of the thermoplastic polyamide powder.

[0014] Preferably, the powder material, which is different from the thermoplastic polyamide powder as defined above, does not contain glass fibers or crushed glass fibers. The thermoplastic polyamide powder may consist of a single thermoplastic polyamide, a mixture of different thermoplastic polyamides, or particles made from a mixture of one or more thermoplastic polyamide species as additives. Typically, the thermoplastic polyamide powder comprises a thermoplastic polyamide powder containing at least 70% by mass of laurolactam (Lc12) and caprolactam (Lc6) based on 100% by mass of the total thermoplastic polyamide powder. Preferably, the additives account for a maximum of 20% by mass, or a maximum of 10% by mass, or a maximum of 5% by mass, based on 100% of the total thermoplastic polyamide powder. According to one preferred embodiment, the thermoplastic polyamide powder consists of only one or more thermoplastic polyamide systems made from only laurolactam (Lc12) and caprolactam (Lc6) without any additives. The additives can be selected as described in further detail below. Alternatively, or furthermore, the thermoplastic polyamide powder of the above-mentioned powder does not contain flame retardant additives. According to yet another preferred embodiment, the thermoplastic polyamide powder comprises the polyamide and an amount of further additives in the range of 20% or less by mass or 15% or less by mass, preferably 1 to 12% or 5 to 10% by mass, relative to the total mass of the powder.

[0015] Preferably, the above additive is one or a combination of the following: fillers, preferably selected from the group consisting of talc, aluminum oxide-based fillers, glass fillers, and metal carbonates containing calcium carbonate; fluidizers, preferably selected from the group consisting of fumed silica or precipitated silica, metal salts of long-chain fatty acids containing metal stearate, titanium dioxide, Group 1 salts, and fumed aluminum oxide; and flame retardants, preferably selected from the group consisting of organic or inorganic monophosphinates or diphosphinates, preferably alkylphosphinate metal salts, particularly aluminum diethylphosphinate, either alone or in combination with synergistic compounds preferably containing nitrogen and / or phosphorus, including melem, melam, melon, or other melamine or derivatives thereof. Preferably, the above additive does not contain glass fibers or crushed glass fibers. Preferably, the powder does not contain glass fibers or crushed glass fibers. Preferably, the thermoplastic pulverized polyamide powder is prepared from a polyamide starting material that does not contain glass fibers, and then pulverized.

[0016] According to the present invention, the above-mentioned thermoplastic pulverized polyamide consists of a polyamide made solely from laurolactam (Lc12) and caprolactam (Lc6), with the proportion of laurolactam being 40-60 mol% of the lactam used. Therefore, there are no further lactams other than laurolactam (Lc12) and caprolactam (Lc6), and no further dibasic acids or diamines are present. In a further aspect of the present invention, the present invention relates to a method for producing thermoplastic polyamide powder used in the processes described above. In one example, the method is characterized in that a particle size distribution suitable for the printing process is obtained, in particular, by appropriate filtering or sieving techniques (tumble air jet screener, ultrasonic tumbler, or air separator). In other examples, the method does not require the use of sieving techniques. Furthermore, in some examples, the above method includes a step of forming a thermoplastic polyamide powder using solvent precipitation, solvent pulverization, melt emulsification, melt pulverization, or another pulverization technique. Furthermore, in some embodiments, the polyamide powder can be blended with one or more additional components or additives, such as additives or fillers, to prepare compositions for use in additional manufacturing. Such compositions can be prepared in some examples by dry blending or wet blending.

[0017] In a further embodiment, the present invention describes powders or compositions used in additive manufacturing, such as SLS, or other additive manufacturing methods in which granular or fine particle materials are selectively melted, fused, sintered, or solidified by other means. In some embodiments, such compositions include, as components, the polyamide powders described herein. The polyamide powders may form all or part of the sinterable powder. In some cases, the polyamide powders are the main or majority component of the sinterable powder composition. For example, in some embodiments, the additive manufacturing compositions described herein include up to 100% by mass, up to 99% by mass, up to 95% by mass, or up to 90% by mass of copolyamide powder, based on the total mass of the sinterable powder. In some cases, the sinterable powder contains 50-100% by mass, 50-99% by mass, 50-90% by mass, 50-80% by mass, 50-70% by mass, 60-100% by mass, 60-99% by mass, 60-90% by mass, 70-100% by mass, 70-99% by mass, 70-90% by mass, 80-100% by mass, 80-99% by mass, 80-95% by mass, 85-100% by mass, 85-99% by mass, 85-95% by mass, 90-100% by mass, or 90-99% by mass of copolyamide powder, based on the total mass of the sinterable powder. In some cases, the sinterable powder further contains another granular component, particulate component, or powder component in addition to the copolyamide powder component. Again, preferably, the other granular components, fine particles, or powder components from the thermoplastic polyamide powder as defined above do not include glass fibers or crushed glass fibers. According to a preferred embodiment, in the thermoplastic pulverized polyamide powder, the proportion of caprolactam is at least 50 mol% of the lactam used, and preferably in the range of 50 to 60 mol% of the lactam used.

[0018] The above-mentioned thermoplastic pulverized polyamide powder preferably has a relative viscosity (measured in m-cresol at a temperature of 20°C and a concentration of 0.5% by mass in accordance with ISO 307) in the range of 1.4 to 1.8, more preferably in the range of 1.5 to 1.75. The above thermoplastic pulverized polyamide powder is more preferably in the range of 110 to 190°C, and more preferably in the range of 120 to 180°C. The above thermoplastic pulverized polyamide powder does not need to have a recrystallization temperature or a low-temperature crystallization temperature. cc ) is taken as the peak value during the second heating cycle; recrystallization temperature (T rc The values ​​recorded are taken during the cooling phase of the first heating cycle, and all measurements are taken in accordance with ISO 11357-3 (2013). Typically, the above powders are suitable for and compatible with the manufacture of molded articles in a layer-by-layer process in which regions of the powder layer are selectively melted by concentrated or non-concentrated input of electromagnetic energy.

[0019] According to a preferred embodiment, in the thermoplastic pulverized polyamide powder, the proportion of caprolactam is in the range of 40 to 60 mol%, preferably 50 to 60 mol%, of the lactam used, the melting point is in the range of 120 to 170°C, preferably 125 to 170°C, and the crystallization temperature is in the range of 100 to 140°C, preferably 90 to 160°C, and the polyamide powder is prepared without chain control. In yet another preferred embodiment, the proportion of caprolactam is in the range of 40-60 mol%, preferably 50-60 mol%, of the lactam used, the melting point is in the range of 150-200°C, preferably 155-195°C, and the crystallization temperature is in the range of 110-170°C, preferably 120-165°C, and the polyamide powder is prepared without chain control. The above powder preferably has a recrystallization temperature (T rc ) is also the low-temperature crystallization temperature (T cc ) also does not have a wide range of possible temperatures for the partial floor temperature. rc T cc If measurement is not possible, this indicates very slow crystallization of the powder over a wide temperature range, which also allows for a wide temperature range during printing. This enables more robust printing parameters. The thermoplastic pulverized polyamide powder can be prepared by a pulverization process, preferably using a low-temperature pulverization process. After pulverization, a sieving or filtering process is preferably performed to produce the desired particle size distribution.

[0020] If necessary for the preparation of the final powder, the thermoplastic polyamide powder may be mixed with other powder particles as further detailed above. The particle size filtering described above may be performed before, after, or both of the mixing with the other powder particles. Preferably, the particle size distribution is such that 80%, preferably 90%, of the particles are located in the size range of 20 to 100 μm, preferably 40 to 90 μm. Preferably, the D10 value measured in accordance with ISO 13322-2 is in the range of 15 to 40 μm, preferably 20 to 30 μm, and / or the D95 value measured in accordance with ISO 13322-2 is in the range of 80 to 99 μm, preferably 85 to 98 μm. Typically, the above powder has a diameter D50 of 50-75 μm, preferably 50-65 μm, and more preferably 50-60 μm, as measured in accordance with ISO 13322-2.

[0021] The above particles preferably have an essentially spherical or potato shape. The above-mentioned thermoplastic pulverized polyamide powder preferably has an MFR value in the range of 7 to 12 g / 10 min, as measured in accordance with ISO 1133. Furthermore, the present invention relates to a copolyamide composed of laurolactam and caprolactam for preparing the powders described in detail above, wherein the proportion of caprolactam is 40 to 60 mol% of the lactam used. Furthermore, the present invention relates to the use of thermoplastic pulverized polyamide powder for the preparation of molded articles in a layer-by-layer process in which selective regions of the powder layer are fused, sintered, melted, or solidified by concentrated or non-concentrated input of electromagnetic energy, wherein the polyamide is composed of, or contains, laurolactam and caprolactam, preferably only thereof, and the proportion of caprolactam is 40 to 60 mol% of the lactam used.

[0022] The present invention also relates to a method for preparing a thermoplastic polyamide powder used in a layer-by-layer process in which a selective region of a powder layer is sintered, melted, or solidified, preferably by concentrated or non-concentrated input of electromagnetic energy, wherein the powder is a thermoplastic pulverized polyamide powder in which the polyamide contains or consists of laurolactam and caprolactam, preferably consisting of only these, the proportion of caprolactam is in the range of 40 to 60 mol% of the lactam used, and preferably the thermoplastic pulverized polyamide powder is prepared by a low-temperature pulverization process. Furthermore, the present invention relates to a method for printing a three-dimensional article, comprising the steps of providing a composition containing a powder as detailed above, and preferably forming the article by selectively solidifying layers of the composition by concentrated or non-concentrated input of electromagnetic energy. Preferably, the composition is provided in a layer-by-layer process. In some embodiments, for example, the compositions for additional manufacturing described herein include a flow aid component. Lastly and importantly, the present invention relates to a molded article prepared using the method described above, or a molded article prepared or formed from the composition or powder described above. Further embodiments are shown in the dependent claims. [Modes for carrying out the invention]

[0023] Preferred embodiments of the present invention are described below based on embodiments, but these are for illustrative purposes only and should not be construed as limiting. The present invention describes condensation reactions, as well as grinding processes and uses. [Examples]

[0024] Process A-copolyamide Caprolactam (40.2 kg, 56 mol%) and laurolactam (53.7 kg, 44 mol%) were transferred to an autoclave with water (3.95 mass%), and the mixture was stirred at 190-200°C for 120 minutes. The mixture was then heated to 270°C, 20 bar, and stirred at 290°C for 5 hours under a constant pressure of 20 bar. The polymer was cooled to 270°C over 4 hours, and the pressure was reduced to 0.3 bar. The temperature was then reduced to 260°C. The polycondensate was then granulated and dried using a standard procedure. Analysis of the granular material: Melting point T m The temperature is 130°C and the glass transition temperature is T g It's 30℃. Process B-Powder The granules obtained in step A were ground into coarse material at -50°C using a Hosokawa 160C pin mill by adding liquid nitrogen flowing in the opposite direction. Subsequently, the coarse material was separated into particles with a particle size distribution of approximately 40-90 μm using an ultrasonic sieve with a screen cloth of a matching mesh size. The measured particle size distribution (μm) was D10: 24.4, D50: 52.9, and D95: 95.3, measured with Camsizer XT in accordance with ISO 13322-2. Further properties of the powder are shown in the table below. Process C: SLS molded product The powder obtained in step C was printed for sample production using a 3D Systems SPro60 SLS printer (equipped with a CO2 laser) (ISO 527). The printer was configured with the parameters shown in the table below.

[0025]

Table 1

[0026] The glass transition temperature (T g ), melting point (T m ) of the pellet / granular material were measured: ISO standards 11357-1, 11357-2, 11357-3 (2013); pelletized material; using a DSC 2920 device from TA Instruments, differential scanning calorimetry (DSC) was performed at a heating rate of 20 K / min and a cooling rate of 5 K / min. The thermogram was analyzed using the Universal Analysis 2000 program from TA Instruments. For the purpose of measuring the glass transition temperature, the sample was quenched in dry ice after the first heating. The glass transition temperature (Tg) was determined during the second heating. The midpoint of the glass transition range was recorded as the glass transition temperature (T g ) and confirmed by the "half-height" method. The glass transition temperature (T g ), melting point (T m ), low-temperature crystallization temperature (T cc ), recrystallization temperature (T rc): ISO standards 11357-1, 11357-2, 11357-3 (2013); powder material; differential scanning calorimetry (DSC) was performed using a TA Instruments DSC 2920 instrument at a heating rate of 20 K / min and a cooling rate of 5 K / min. Thermograms were analyzed using the TA Instruments Universal Analysis 2000 program.

[0027] To measure the glass transition temperature, the sample was quenched in dry ice after the first heating. During the second heating, the glass transition temperature (T g The midpoint of the glass transition range is the glass transition temperature (T g This was recorded as such and confirmed by the "half-height" method. Low temperature crystallization temperature (T cc ) is taken as the peak value during the second heating cycle; recrystallization temperature (T rc ) The value taken during the cooling phase of the first heating cycle is recorded.

[0028] [Table 2] The powder according to the present invention can be printed at relatively low, energy-efficient temperatures, and while it offers significantly better mechanical properties, particularly in terms of impact strength and elongation at break, compared to other commonly printed SLS powders such as PP, PA11, and PA12, it is a material that provides excellent mechanical properties. A good surface appearance is also achieved in printing using the powder of the present invention.

[0029] The powder according to the present invention is T cc and T rc It was not possible to measure this, which provides a large sintering window / temperature range for 3D printing. Two comparative examples, PP and PA11, had peaks in the DSC measurement, with sintering windows read in the ranges of 20°C and 25°C, respectively, and melting temperature T m and recrystallization temperature T rc The window between (Tm -T rc ) is defined as. On the other hand, in Example 1 according to the present invention, crystallization is very slow, and this peak is no longer detectable, thus a wide range of crystallization temperatures exists. The comparative system PA12 has a sintering window of about 30°C according to the above definition, and only a 5°C efficiently usable temperature window of the powder bed during printing. The powder according to the present invention in Example 1 has a temperature range that is twice as wide (about 10°C) for efficient use, but there is no measurable sintering window.

Claims

1. A powder for manufacturing molded articles in a layer-by-layer process, The powder is a thermoplastic pulverized polyamide powder consisting of laurolactam and caprolactam. The proportion of caprolactam used is 40-60 mol% of the lactam. In a layer-by-layer process, regions of the powder layer are selectively melted, sintered, fused, or solidified. The aforementioned powder.

2. The powder according to claim 1, wherein the proportion of caprolactam in the thermoplastic pulverized polyamide powder is at least 50 mol%, preferably 50 to 60 mol%, of the lactam used.

3. The relative viscosity of the thermoplastic pulverized polyamide powder (measured in m-cresol at a temperature of 20°C and a concentration of 0.5% by mass in accordance with ISO 307) is in the range of 1.4 to 1.8, preferably in the range of 1.5 to 1.

75. and / or the melting point of the thermoplastic pulverized polyamide powder is in the range of 110 to 190°C, preferably in the range of 120 to 180°C. The powder according to claim 1 or 2, wherein the crystallization temperature of the thermoplastic pulverized polyamide powder is in the range of 80 to 170°C, preferably in the range of 90 to 160°C.

4. The powder according to claim 1 or 2 for the manufacture of a molded article in a layer-by-layer process in which a region of the powder layer is selectively melted by concentrated or non-concentrated input of electromagnetic energy.

5. The powder according to claim 1 or 2, wherein the proportion of caprolactam in the thermoplastic pulverized polyamide powder is in the range of 40 to 60 mol%, preferably 50 to 60 mol%, of the lactam used, the melting point is in the range of 120 to 170°C, preferably 125 to 170°C, the crystallization temperature is in the range of 100 to 140°C, preferably 90 to 160°C, and the polyamide powder is prepared without chain control.

6. The powder according to claim 1 or 2, wherein the proportion of caprolactam is in the range of 40 to 60 mol%, preferably 50 to 60 mol%, of the lactam used, the melting point is in the range of 150 to 200°C, preferably 155 to 195°C, the crystallization temperature is in the range of 110 to 170°C, preferably 120 to 165°C, and the polyamide powder is prepared without chain control.

7. The powder according to claim 1 or 2, wherein the powder has neither a recrystallization temperature nor a low-temperature crystallization temperature.

8. The powder according to claim 1 or 2, wherein the thermoplastic pulverized polyamide powder is prepared by a low-temperature pulverization process.

9. The diameter D50 of the powder, measured in accordance with ISO 13322-2, is 50 to 75 μm, preferably 50 to 65 μm, and more preferably 50 to 60 μm. and / or the MFR value of the thermoplastic pulverized polyamide powder, measured in accordance with ISO 1133, is in the range of 7 to 12 g / 10 min. The powder according to claim 1 or 2, characterized in that it is the powder described in claim 1 or 2.

10. A copolyamide comprising laurolactam and caprolactam for preparing the powder according to claim 1 or 2, wherein the proportion of caprolactam is 40 to 60 mol% of the lactam used.

11. The use of thermoplastic pulverized polyamide powder for the preparation of molded articles in a layer-by-layer process, The polyamide comprises laurolactam and caprolactam, preferably comprising only laurolactam and caprolactam. The proportion of caprolactam used is 40-60 mol% of the lactam. The use wherein a selective region of the powder layer is fused, sintered, melted, or solidified, preferably by concentrated or non-concentrated input of electromagnetic energy.

12. A method for preparing thermoplastic polyamide powder used in a layer-by-layer process, A selective region of the powder layer is sintered, melted, or solidified, preferably by concentrated or non-concentrated input of electromagnetic energy. The powder is a thermoplastic pulverized polyamide powder containing laurolactam and caprolactam, or consisting of laurolactam and caprolactam, preferably consisting only of laurolactam and caprolactam. The proportion of caprolactam used is in the range of 40-60 mol% of the lactam used. Preferably, the thermoplastic pulverized polyamide powder is prepared by a low-temperature pulverization process in the method described above.

13. A method for printing three-dimensional objects, A step of providing a composition containing the powder described in claim 1, and A step of selectively solidifying layers of a composition to form an article, preferably a step of selectively solidifying layers of a composition to form an article by concentrated or non-concentrated input of electromagnetic energy. Includes, Preferably, the composition is provided by a layer-by-layer process.

14. A molded article prepared using the method described in claim 12 or 13.