DE102018121230A1 - Process for additive manufacturing of workpieces from a flame-retardant polyamide material, thereby obtainable workpieces and use of the polyamide material - Google Patents

Abstract

The invention relates to a method for the additive manufacturing of flame-retardant workpieces with improved fire behavior. For this purpose, polyamide materials are provided which contain a flame retardant which is selected from one or more of red phosphorus, phosphorus-containing compounds and flame retardants based on melamine. In particular, powdery flame-retardant polyamide materials are provided which are suitable for selective laser sintering. The workpieces produced by selective laser sintering from these powdered flame-retardant polyamide materials show not only the good fire behavior but also a surprisingly high surface smoothness. A polyamide material made of polyamide 6 and red phosphorus is particularly suitable. The workpieces can be used in the interior of aircraft, especially in the pressurized area.

Description

The invention relates to a method for the additive manufacturing of a workpiece from a flame-retardant polyamide material and the workpieces obtainable by this method.

It also relates to a flame-retardant powdered polyamide material and its use in a process for additive manufacturing.

Additive manufacturing processes were initially used primarily for the production of individual prototypes (“rapid prototyping”). With the improvement of manufacturing processes, additive manufacturing processes are becoming increasingly important for the production of series products ("rapid manufacturing").

Selective laser sintering (SLS) is one of the additive manufacturing processes used in industry. An essential application of selective laser sintering is in the production of objects from a thermoplastic. The thermoplastics that can be used in the SLS process are also referred to below as thermoplastic polymer materials or polymer materials for short.

When selecting the polymer materials that can be used in the SLS process, one starts from the polymer materials that lead to products with the desired property profile in isotropic production processes, such as the injection molding of a polymer mass softened in an extruder. These include, for example, good mechanical properties such as tensile strength, and chemical properties such as resistance to lubricants and fuels and good fire protection properties. For fire protection, polymers are usually given flame retardants with flame retardants.

In addition, the polymer materials must be suitable for use under the specific process conditions of selective laser sintering. For example, at the high temperature of the powder bed near the melting temperature of the polymer material, the polymer particles must be able to be distributed evenly with a doctor blade to form a thin layer. They are intended to supply a powder bed that is quiet even when a protective gas flows through it. With regard to the end product, it is necessary that products sintered with the powdery polymer material are obtained with a suitable porosity. The porosity of the sintered polymer is crucial for the strength of the finished workpiece. In addition, the powdery polymer material must be constructed and the selective laser sintering must be carried out so that there is no oversintering.

A variety of polymer materials can be used in selective laser sintering. Polyolefins, polycarbonates, polyamides, polyvinyl chlorides, polybutylene terephthalates, polyacetals, polystyrenes can be used. However, the number of industrially usable polymer materials is rather small for demanding applications in the high-performance range. The existing materials sometimes show an inadequate property profile.

Particularly high performance is expected from polymer materials that are used in aircraft construction. For this area of application, polyamide materials have an advantageous property profile. They have high strength and rigidity, good chemical resistance and long-term stability. In addition, they are well suited for selective laser sintering due to their good separation resolution, their level of detail and the post-treatment options.

So that polyamide materials can be used in aircraft construction, they must be equipped with flame retardants. Inorganic-mineral flame retardants, nitrogen-containing flame retardants, phosphorus-containing flame retardants and halogen-containing flame retardants are available for the flame-retardant finishing of polymers. The problem with the introduction of such flame retardants is that they can influence the chemical and physical properties of polyamide materials.

The multitude of requirements placed on polymer materials for additive manufacturing processes, in particular selective laser sintering, has led to the development of powdery special products suitable for additive manufacturing. Powdery polymer materials available on the market have therefore been specially optimized for selective laser sintering and are typically not used in injection molding and extrusion processes.

A flame-retardant polyamide material specially developed for additive manufacturing is commercially available from EOS GmbH under the name PA 2241 FR. This is a polyamide 12 that contains a halogen-containing flame retardant. PA 2241 FR is a white polymer powder and, due to its flame-retardant properties, can be used as a high-performance plastic in the aerospace industry.

Another flame-retardant polyamide material specially developed for additive manufacturing is commercially available from EOS GmbH under the name PA 2210 FR. This is a polyamide 12 that contains a halogen-free flame retardant. PA 2210 FR is a white polymer powder for which aerospace, electrical engineering and electrics are specified as possible areas of application.

It is an object of the present invention to provide an improved method for the additive manufacturing of a workpiece from a flame-retardant polyamide material.

It is a further object of the present invention to provide improved flame-retardant workpieces obtainable by additive manufacturing.

It is a further object of the present invention to provide improved flame-retardant polyamide materials which are suitable for use in an additive manufacturing process.

According to a first aspect, the invention relates to a method for additively manufacturing a workpiece from a flame-retardant polyamide material, the flame retardant for the flame retardant finishing of the polyamide material being selected from one or more of red phosphorus, phosphorus-containing compounds and flame retardants based on melamine.

The flame retardant used in the polyamide material may consist of a single one of the above materials, such as red phosphorus, or a combination of the above materials, such as red phosphorus and a melamine based flame retardant.

The additive manufacturing process can essentially be a process carried out in a powder bed, such as selective laser sintering (SLS), selective laser melting (SLM) or selective absorbing sintering (SAS). The flame-retardant polyamide materials can also be used in fused deposition modeling, fused layer modeling (FLM), mask sintering and polyjet modeling. The flame-retardant polyamide material is processed in the form of a filament or in the form of pellets.

1. a) Bereitstellen des flammhemmend ausgerüsteten Polyamidmaterials in Form eines Pulvers,
2. b) Aufbringen des pulverförmigen, flammhemmend ausgerüsteten Polyamidmaterials auf eine Unterlage unter Erhalt einer Pulverschicht;
3. c) selektives Bestrahlen der Bereiche der Pulverschicht, die für die Werkstückbildung vorgesehen sind, mit einer Strahlung, insbesondere Laserstrahlung, die dafür geeignet ist, die Partikel der Pulverschicht in diesen Bereichen durch Sintern oder Schmelzen und Erstarren miteinander zu verbinden;
4. d) Wiederholen der Schritte b) und c) oberhalb der jeweils zuletzt bestrahlten Pulverschicht als Unterlage, bis das Werkstück aus flammhemmend ausgerüstetem Polyamidmaterial ausgebildet ist,
5. e) Trennen des Werkstücks von dem nicht durch Sintern oder Schmelzen und Erstarren verfestigten pulverförmigen, flammhemmend ausgerüsteten Polyamidmaterial.

It is preferred that the method comprises the following steps:

1. a) providing the flame-retardant polyamide material in the form of a powder,
2. b) applying the powdered, flame-retardant polyamide material to a base to obtain a powder layer;
3. c) selective irradiation of the areas of the powder layer intended for workpiece formation with radiation, in particular laser radiation, which is suitable for connecting the particles of the powder layer in these areas by sintering or melting and solidification;
4. d) repeating steps b) and c) above the respectively last irradiated powder layer as a base until the workpiece is made of flame-retardant polyamide material,
5. e) separating the workpiece from the powdery, flame-retardant polyamide material which has not been solidified by sintering or melting and solidification.

The powdery flame-retardant polyamide material is well suited for processing in a powder bed. It can be spread easily and homogeneously with a doctor blade on the powder bed of the build platform and shows a very good flow behavior in the sintering process and in connection with this an advantageous layer application and particle arrangement.

Furthermore, good material consolidation and shape retention, such as little distortion, is found during laser sintering. The processing window or process window is significantly enlarged. Powdery Polyamide material that was not solidified during laser sintering can be reused in the installation space. The refresh rate of the laser sinter powder is high.

The workpiece obtained, which is based on a polyamide material and at least one flame retardant, such as red phosphorus, showed improved results in the fire test according to AITM-0002 method B (measurement of the fire length), according to AITM2-0007 (measurement of the smoke density) and AITM3-0005 (toxicity) Fire and toxicity properties.

Another advantage of the method according to the invention is that the workpiece, which is additively manufactured from a powder, is obtained with a higher surface smoothness after it has been removed from the powder bed.

It is preferred that the polyamide material comprises one or more polyamides or a polymer blend of one or more polyamides with one or more miscible, compatible or immiscible polymers, which are selected in particular from polyolefins, polystyrenes, thermoplastic elastomers and polyacetals, the polyamide content in the Polymer blend is at least 30% by weight, preferably at least 50% by weight, preferably at least 70% by weight, more preferably at least 90% by weight.

It is preferred that the one or more phosphorus-containing compounds be selected from a group comprising: aromatic and aliphatic esters of phosphoric acid, such as resorcinol bis (diphenyl phosphate) (RDP), bisphenol A bis (diphenyl phosphate) (BPD) and their oligomers, triphenylphosphate (TPP), tris (2-ethylhexyl) phosphate (TEHP), tricresylphosphate (TKP), isopropylated triphenylphosphate (ITP), ethylenediamine diphosphate, ammonium phosphate, ammonium polyphosphate, phosphinates such as salts and their hypophosphorus derivatives, such as salts and their hypophosphorus phosphorous derivatives Alkyl phosphinate salts, e.g. B. diethylene phosphinate aluminum or diethylene phosphinate zinc or aluminum phosphinate, aluminum phosphite, aluminum phosphonate, phosphonate esters, oligomers and polymeric derivatives of methanephosphonic acid, 9,10-dihydro-9-oxa-10-phosphorylphenanthrene-10-oxide, ammonium polyphosphate, phosphacenes, vinylphosphonates.

In a preferred embodiment, the flame retardant can consist of red phosphorus or contain red phosphorus.

It is preferred that the one or more melamine-based flame retardants be selected from a group comprising: melamine, melamine derivatives, melamine condensation products, melamine salts, melem, melam, melon, benzoguanamine, allantoin, polyisocyanurate, melamine cyanurate, melamine phosphate, dimelamine phosphate, melamine pyrophosphate Melamine polyphosphate, melamine metal phosphates, such as melamine aluminum phosphate, melamine zinc phosphate, melamine magnesium phosphate, the corresponding pyrophosphates and polyphosphates, poly- [2,4- (piperazin-1,4-yl) -6- (morpholin-4-yl) -1, 3,5-triazine].

It is preferred that the flame retardant is incorporated into the polyamide material in a proportion in the range from 0.1 to 20% by weight, preferably 1 to 15% by weight, based on the total weight of the flame-retardant polyamide material.

It is preferred that the polyamide material contain one or more polyamides selected from the group consisting of polyamide 6, polyamide 11, polyamide 12, polyamide 6.6, polyamide 6.9, polyamide 6.10, polyamide 6.12, polyamide 10.10 and copolyamides thereof, such as polyamide 6/12, PA 6.6 / 6.10, or consists of one or more of these polyamides.

It is particularly preferred that the polyamide material consists of polyamide 6 or polyamide 6 in a proportion of at least 30% by weight, preferably at least 50% by weight, preferably at least 70% by weight, more preferably at least 90% by weight contains.

A powdered flame-retardant polyamide material, which delivers particularly good results with selective laser sintering, comprises polyamide 6 and red phosphorus (hereinafter abbreviated to: PA6-RP), the red phosphorus preferably being contained in a proportion of 1 to 15% by weight. The workpiece obtained by selective laser sintering from PA6-RP shows good fire properties, which are also retained in connection with lacquers. With a higher proportion of red phosphorus, such as 14%, V0 can also be achieved in the UL-94 standard. An important fire property is achieved, such as z. B. is required in the railway industry. PA6-RP workpieces show improved fire testing according to AITM-0002 method B (measurement of fire length), according to AITM2-0007 (measurement of smoke density) and AITM3-0005 (toxicity) Characteristics. A heat resistance up to at least 85 ° C was determined. Due to this fire behavior, workpieces available from PA6-RP in the additive manufacturing process can be used for the interior of aircraft.

Powdered PA6-RP shows a very good flow behavior in the sintering process with regard to layer application and particle arrangement. The material consolidates well. A high degree of form accuracy (little distortion) is found. The processing window (process window) is significantly enlarged. Powdered PA6-RP that has not solidified can be reused in the installation space. It shows a high refresh rate.

Workpieces manufactured with PA6-RP additively by selective laser sintering show a higher surface smoothness after removal from the powder bed.

It is preferred that the polyamide material contains, in addition to the flame retardant, further auxiliaries, in particular antistatic agents, dyes, such as soluble inorganic and / or organic pigments and / or insoluble dyes, fillers, such as glass fibers, chalk, graphite, carbon black, Lubricants, stabilizers and plasticizers can be selected.

It is preferred that the powdery, flame-retardant polyamide material has a particle size, in particular in the range from 40 to 110 μm.

• - Herstellen eines Gemischs oder Compounds aus dem Polyamidmaterial und dem Flammschutzmittel, insbesondere in Form eines gegossenen Blocks oder eines in einem Extruder hergestellten Granulats oder eines körnigen Materials,
• - Zerkleinern des Blocks oder des Granulats oder des körnigen Materials durch mechanisches Bearbeiten, vorzugsweise Mahlen, besonders bevorzugt kryogenes Mahlen, zu einem pulverförmigen Material, und
• - Sieben des pulverförmigen Materials unter Erhalt einer Siebfraktion des pulverförmigen Materials mit der für die additive Fertigung gewünschten Korngrößenverteilung.

It is preferred that one, several or all of the following steps are carried out to provide a powdered, flame-retardant polyamide material:

• Producing a mixture or compound from the polyamide material and the flame retardant, in particular in the form of a cast block or a granulate or a granular material produced in an extruder,
• Comminution of the block or the granulate or the granular material by mechanical processing, preferably grinding, particularly preferably cryogenic grinding, to a powdery material, and
• - Sieving the powdery material to obtain a sieve fraction of the powdery material with the grain size distribution desired for additive manufacturing.

If necessary, the angular surface of the particles of the powdery material obtained after grinding can be rounded before or after sieving.

It is preferred that in step c) the powder layer is irradiated with laser radiation with a wavelength that lies within the absorption band of the flame retardant, in particular of red phosphorus. In this case, the absorption by the flame retardant contributes to the required heating of the sintered powder.

It is alternatively preferred that in step c) the powder layer is irradiated with laser radiation with a wavelength which lies outside the absorption band of the flame retardant, in particular of red phosphorus, which is in particular on the long-wave side of visible light or more precisely in the infrared region -Radiation is or is above 3000 nm. When the powder layers are exposed outside the absorption band of the flame retardant, in particular red phosphorus, the required heating of the sintered powder advantageously takes place predominantly by absorption of the polyamide material.

It is also preferred that in step c) the laser radiation is emitted by an infrared laser, such as a CO ₂ laser, an Nd: YAG laser or a fiber laser.

It is preferred that the laser energy radiated in step c) is in the range from approximately 0.10 to 0.30 J / mm ³ , preferably approximately 0.15 to 0.25 J / mm ² , in particular approximately 0.2 J / mm ² mm ³ lies. The procedure for determining the optimally radiated energy is described in connection with the exemplary embodiment.

According to a further aspect, the invention relates to a flame-retardant workpiece that can be obtained by an additive manufacturing process as described above.

According to a further aspect, the invention relates to the use of a flame-retardant polyamide material, which is as defined above and in particular is in powder form, for additive manufacturing, in particular by selective laser sintering or selective laser melting, one flame-retardant workpiece, in particular a flame-retardant workpiece with a high surface smoothness.

According to a further aspect, the invention relates to a flame-retardant polyamide material, as defined above and in particular in powder form, for the additive manufacturing of a flame-retardant workpiece, in particular by selective laser sintering or selective laser melting.

• - Herstellen eines Gemischs oder Compounds oder Blends aus dem Polyamidmaterial und dem Flammschutzmittel, insbesondere in Form eines gegossenen Blocks oder eines in einem Extruder hergestellten Granulats oder eines körnigen Materials,
• - Zerkleinern des Blocks oder des Granulats oder des körnigen Materials durch mechanisches Bearbeiten, insbesondere Mahlen, vorzugsweise kryogenes Mahlen, zu einem pulverförmigen Material, und
• - Sieben des pulverförmigen Materials unter Erhalt einer Siebfraktion des pulverförmigen Materials mit der für die additive Fertigung gewünschten Korngrößenverteilung.

It is preferred that the flame retardant powdered polyamide material is obtainable from

• Producing a mixture or compounds or blends from the polyamide material and the flame retardant, in particular in the form of a cast block or a granulate or a granular material produced in an extruder,
• Comminuting the block or the granulate or the granular material by mechanical processing, in particular grinding, preferably cryogenic grinding, to a powdery material, and
• - Sieving the powdery material to obtain a sieve fraction of the powdery material with the grain size distribution desired for additive manufacturing.

Before or after the sieving, the angular surface of the particles of the powdery material obtained after grinding can be rounded off.

The additive manufacturing method according to the invention, in particular selective laser sintering, can be used for the manufacture of various workpieces, in particular components for interior applications in aircraft, such as interior fittings, for example system installations. Edge protection molded parts for protecting sandwich components in the interior of an aircraft, such as corner connector bumper strips, can be produced. The improved flame retardant properties through the combination of a polyamide material with a flame retardant as defined above, such as in particular red phosphorus, is particularly important for the pressurized area of the aircraft.

• 1 graphische Darstellungen der Ergebnisse der Messung des Lawinenwinkels und der Lawinenenergie der untersuchten Polyamidpulver in einem Revolution Powder Analyzer,
• 2 graphische Darstellungen der Ergebnisse der Messung des Oberflächenfraktals und der Oberflächenlinearität der untersuchten Polyamidpulver in einem Revolution Powder Analyzer;
• 3 die fotografische Darstellung des Fließverhalten von in der Trommel des Revolution Powder Analyzers in Drehung versetzten pulverförmigen Polyamidmaterialien;
• 4 eine Anlage für die Durchführung der additiven Fertigung von erfindungsgemäßen Werkstücken und dem Vergleich dienenden Werkstücken;
• 5 ein Diagramm, in dem die Bauteildichte in Abhängigkeit von der Volumenenergiedichte aufgetragen ist.

The invention is explained below using an exemplary embodiment with reference to FIG 1 to 5 described in which show:

• 1 graphical representation of the results of the measurement of the avalanche angle and the avalanche energy of the investigated polyamide powder in a revolution powder analyzer,
• 2 graphical representation of the results of the measurement of the surface fractal and the surface linearity of the examined polyamide powder in a Revolution Powder Analyzer;
• 3 the photographic representation of the flow behavior of powdered polyamide materials rotated in the drum of the Revolution Powder Analyzer;
• 4 a system for carrying out the additive manufacturing of workpieces according to the invention and the workpieces used for comparison;
• 5 a diagram in which the component density is plotted as a function of the volume energy density.

Three powdered polyamide materials are characterized with regard to their powder properties. A flame-retardant polyamide material according to the invention, which comprises polyamide 6 as a polymer base and red phosphorus as a flame retardant (hereinafter referred to as PA6-RP), a polyamide material made from polyamide 6 without a flame retardant (hereinafter referred to as PA6) as a first comparison and a polyamide material made from polyamide 12 are examined Proven suitability for selective laser sintering as a second comparison (hereinafter referred to as PA12).

The powdered PA6-RP and the powdered PA6 are processed into specimens by selective laser sintering.

The proportion of red phosphorus in the PA6-RP can advantageously be 1 to 15%. The PA6-PR used in the following experiments contains 3 to 6% red phosphorus.

Production and characterization of the powders for selective laser sintering

A1. production method

A cast PA6-RP block or a coarse-grained granulate is used as the starting material for the production of the PA6-RP sinter powder. The block or the granulate is cryogenically ground with a mill to a fine, powdery material. By sieving the powdery material, a sieve fraction with a grain size distribution desired for additive manufacturing is obtained. After cryogenic grinding, the particles have, for example, a particle size in the range from 40 to 110 μm and in particular an angular, irregular surface.

The comparative powdered PA6 without flame retardant is produced using the same process.

A2. Characterization of the powdered polyamide materials in a Revolution Powder Analyzer

• 1 zeigt den Lawinenwinkel und die Lawinenenergie von pulverförmigem PA6-RP, PA6 und PA12.
• 2 stellt das Oberflächenfraktal bzw. die Oberflächenrauheit und die Oberflächenlinearität der dieser drei Pulver dar.
• 3 zeigt drei Fotos, die das Fließverhalten von pulverförmigem PA6-RP und pulverförmigem PA6 bei einer Drehgeschwindigkeit von 10 min^-1 im Revolution Powder Analyzer zeigen. Aufnahmebedingungen: 10 Bilder/Sekunde (FPS).
  1. (I) Standardmessung von PA6-RP bei Raumtemperatur;
  2. (II) Standardmessung von PA6 bei Raumtemperatur;
  3. (III) Temperierte Messung von PA6 bei 100 °C.

Powdered PA6-RP, PA6 and PA12 are analyzed in a Revolution Powder Analyzer (RPA). In this way, the flow behavior, the fluidizability and the granulation of the powdery materials can be measured and the suitability for selective laser sintering can be estimated.

• 1 shows the avalanche angle and the avalanche energy of powdered PA6-RP, PA6 and PA12.
• 2 represents the surface fractal or surface roughness and the surface linearity of these three powders.
• 3 shows three photos showing the flow behavior of powdered PA6-RP and powdered PA6 at a rotation speed of 10 min ^-1 in the Revolution Powder Analyzer. Recording conditions: 10 frames / second (FPS).
  1. (I) standard measurement of PA6-RP at room temperature;
  2. (II) standard measurement of PA6 at room temperature;
  3. (III) Temperature-controlled measurement of PA6 at 100 ° C.

Selective laser sintering of powdered PA6-RP and PA6

The powdered PA6-RP and PA6 thus obtained are placed in the powder storage container 118 the manufacturing device 100 according to 4 given. The optimal laser energy is first determined in laser sintering experiments. Subsequently, test specimens for further investigations are produced by selective laser sintering.

B1. Implementation device

The preliminary tests for determining the density of the workpieces as a function of the exposure parameters and the production of test specimens are carried out in a conventional laser sintering system 4 schematically illustrated manufacturing device 100 equivalent.

The manufacturing device 100 has a CO ₂ laser 104 , a system for guiding the laser beam 106 , a powder bed 108 with a vertically movable construction platform 110 in which the workpiece 102 arises, a powder storage container 118 , a powder container 124 and a powder application device 112 with a squeegee 120 on. Next is a control device 114 intended to control the manufacturing process. In particular, the control device controls 114 the laser beam steering device 106 and thus the speed of the focused laser in the building plane, the laser power, the vertical movement of the building platform 110 and the horizontal movement of the powder application device 112 , The laser sintering system also has one or more heating devices for heating the powdered polyamide material or material powder 116 in the powder bed to a temperature above the glass transition temperature and below the melting temperature of the powdered polyamide material (heaters not shown).

The sinter powder produced under A. 116 PA6-RP or PA6 become in the laser beam powder bed manufacturing device 100 to the workpiece 102 shaped.

The CO ₂ laser 104 generates a high-energy laser beam at a wavelength of 10.6 µm, with which the powdered PA6-RP and the powdered PA6 are shaped into test specimens.

For the layer-by-layer generation of the workpiece 102 the powdered PA6-RP 116 from the powder reservoir 118 with the squeegee 120 on the build platform 110 evenly and repeatedly distributed in thin powder layers. On the opposite side of the build platform 110 is a powder container 124 provided that takes up excess powdered PA6-RP or PA6.

In the control device 114 are data about the shape of the workpiece 102 for example in the form of CAD data. The control device 114 then directs the laser beam 122 by means of the laser beam steering device 106 so that the entire cross section of the workpiece 102 is solidified at the level of this layer. The control device then moves 114 the build platform 110 down by a certain amount, so as to apply the next layer of powder and solidify the cross-section again.

B2. Definition of the parameters for PA6-RP

Selective laser sintering produces porous workpieces, with the porosity and density of the material depending on the exposure parameters, such as beam diameter and beam power and the speed at which the laser beam moves across the powder layer. These physical parameters determine the amount of energy introduced into a certain volume of the powder layer (measured quantity here is J / mm3). Since the porosity and density of the sintered workpiece are decisive for the material properties, such as workpiece strength, the best exposure conditions for PA6-RP are determined in preliminary tests. Table 1 shows the results for 19 tests with different parameters, Table 2 the results of the density measurement and the evaluation. The evaluation is made with: +++ (particularly well suited), ++ (well suited) to + (usable). Table 1: Determination of the laser parameters for the selective laser sintering of PA6-RP and PA6 p _Fabs V _F h _F n _F p ₀ v ₀ n ₀ E rating [W] [mm / s] [mm] [-] [W] [mm / s] [-] [J / mm ³ ] 1 20th 5080 0.15 1 10 1778 1 0.262 +++ 2 25th 5080 0.15 1 10 1778 1 0.325 ++ 3 30th 5080 0.15 1 10 1778 1 0.394 + 4 20th 5080 0.5 1 10 1778 1 0.197 ++ 5 25th 5080 0.2 1 10 1778 1 0.246 ++ 6 30th 5080 0.2 1 10 1778 1 0.295 ++ 7 35 5080 0.2 1 10 1778 1 0.344 + 8th 40 5080 0.2 1 10 1778 1 0.394 + 9 20th 5080 0.25 1 10 1778 1 0.157 ++ 10 25th 5080 0.25 1 10 1778 1 0.197 ++ 11 30th 5080 0.25 1 10 1778 1 0.236 +++ 12 35 5080 0.25 1 10 1778 1 0.276 +++ 13 40 5080 0.25 1 10 1778 1 0.315 + 14 20th 5080 0.3 1 10 1778 1 0.131 ++ 15 25th 5080 0.3 1 10 1778 1 0.164 ++ 16 30th 5080 0.3 1 10 1778 1 0.197 +++ 17 20th 5080 0.12 1 10 1778 1 0.328 + 18th 35 5080 0.15 1 10 1778 1 0.459 + 19 40 5080 0.15 1 10 1778 1 0.525 + Table 2: Density measurement and evaluation Density measurement evaluation Dimension [mm] Dimension x [m / m] Dimension y [mm] Dimension z [mm] Weight [g] Weight [g] Density 1 [g / cm ³ ] Density 2 [g / cm ³ ] Density ethanol [g / cm ³ ] Density ethanol [g / cm ³ ] Energy input [J / mm ³ ] Density averaged by hand [g / cm ³ ] Density of ethanol averaged [g / cm ³ ] 1 15 * 15 15.59 15.45 15.48 15.39 10.13 10.08 2,678 2,612 1,095 1,090 1,150 1,142 0.262 0.1093 1,146 2 15 * 17 15.87 15.71 17.71 17.58 10.22 10.24 3,024 3.114 1,053 1.101 1,111 1,151 0.328 1,077 1,131 3 15 * 19 16.34 16.48 20.48 20.58 10.53 10.56 2,970 3,371 0.843 0.941 0.915 1,032 0.394 0.892 0.937 4 15 * 21 15.41 15.39 21.32 21.33 10.13 10.05 3,536 3,485 1,062 1,056 1,123 1,114 0.197 1,059 1,118 5 15 * 23 15.43 15.45 23.37 23.28 10.20 10.31 4,040 3,991 1,098 1,076 1,143 1,138 0.246 1,087 1,141 6 15 * 25 15.77 15.78 25.78 25.76 10.31 10.38 4,520 4,588 1,078 1,087 1,126 1,142 0.295 1,083 1,134 7 15 * 27 16.02 15.91 28.03 27.94 10.40 10.47 4,542 4,988 0.973 1,072 1,018 1,118 0.344 1,022 1,068 8th 17 * 17 18.34 18.27 18.28 18.50 10.48 10.56 3,137 3,551 0.893 0.995 0.944 1,054 0.394 0.44 0.999 9 17 * 19 17.27 17.23 19.29 19.24 10.00 9.97 3,519 3,456 1,056 1,046 1,087 1,076 0.157 1,051 1,082 10 17 * 21 17.32 17.32 21.33 21.31 10.21 10.09 4,068 3,992 1,078 1,072 1.108 1.105 0.197 1,075 1,106 11 17 * 23 17.43 17.52 23.44 23.56 10.26 10.26 4,636 4,657 1,106 1,100 1,156 1,154 0.236 1.103 1,155 12 17 * 25 17.67 17.85 25.57 25.68 10.27 10.37 5,097 5.203 1,098 1,095 1,147 1,156 0.276 1,097 1,151 13 17 * 27 17.93 18.08 27.79 27.94 10.37 10.50 5,451 5,723 1,055 1,079 1,118 1,152 0.315 1,067 1,135 14 19 * 19 19.04 19.30 19.15 19.24 9.97 9.98 3,863 3,898 1,063 1,052 1,141 1,139 0.131 1,057 1,140 15 19 * 21 19.21 19.20 21.20 21.24 10.08 10.04 4,408 4,383 1,074 1,070 1,152 1,151 0.164 1,072 1,151 16 19 * 23 19.47 19.64 23.31 23.46 10.11 10.23 5,123 5.203 1,117 1.104 1,178 1,175 0.197 1,110 1,176 17 19 * 25 20.12 20.43 25.90 26.25 10.36 10.60 5,950 6,168 1,102 1,085 1,177 1,181 0.328 1,094 1,179 18th 19 * 27 21.47 21.36 29.00 28.80 11.32 11.40 6,605 7,226 0.937 1,030 1,005 1.105 0.459 0.984 1,055 19 21 * 21 23.63 23.32 23.80 23.47 11.42 11.83 5,912 6,599 0.921 1,019 1,021 1,125 0.525 0.970 1,073 1,058 1,117

The preliminary tests and their evaluation according to Tables 1 and 2 to determine the density as a function of the exposure parameters are shown in 5 summarized. Then a maximum component density with a volume energy density (J / mm ³ ) of 0.197 J / mm ³ and with a volume energy density of 0.328 J / mm ³ .

For the volume energy density of approximately 0.2 J / mm ³ , an even better sintering result is found compared to approximately 0.33 J / mm ³ . The greatest component density with the best sintering result is thus obtained with a volume energy density of approximately 0.2 J / cm ³ .

B3. Production of test specimens for the analysis of fire behavior

In the manufacturing device 100 after determining the advantageous volume energy density of the workpiece 102 made from PA6-RP and PA6 in the form of test specimens for the investigation of fire behavior. After complete additive manufacturing, the test specimens are pulled out of the powder bed. Loose sinter powder adhering to the test specimens can be easily removed. The surface of the test specimen is smooth.

The fire tests are carried out according to the standards AITM2-0002 (flammability), method B, AITM- 0007 (Smoke test) and AITM3-0005 (toxicity). The following results are obtained: characteristics 1 mm 2.5 mm 3 mm Flammability, vertical 12 s Fire length 51 mm 37 mm 39mm Afterburn time 1s 5s 4s Afterburn time of drops 0 s 0 s 0 s Smoke density 38 56 47 toxicity passed passed passed (NOx = 81)

With these fire properties, PA6-RP is suitable for the production of components for the interior of aircraft, such as the pressurized area.

Reference list

100

Laser beam powder bed manufacturing device

102

workpiece

104

CO ₂ laser

106

Laser beam steering device

108

Powder bed

110

Construction platform

112

Powder application device

114

control device

116

Material powder

118

Powder storage container

120

Squeegee

122

laser beam

124

Powder collecting container

Claims (15)

Method for additively manufacturing a workpiece from a flame-retardant polyamide material, the flame retardant for the flame-retardant finishing of the polyamide material being selected from one or more of red phosphorus, phosphorus-containing compounds and flame retardants based on melamine. Procedure according to Claim 1 , which comprises the following steps: a) providing the flame-retardant polyamide material in the form of a powder, b) applying the powdery, flame-retardant polyamide material to a base to obtain a powder layer; c) selective irradiation of the areas of the powder layer which are provided for the workpiece formation with radiation which is suitable for connecting the particles of the powder layer in these areas by sintering or melting and solidification; d) repeating steps b) and c) above the respectively last irradiated powder layer as a base until the workpiece is made of flame-retardant polyamide material, e) separating the workpiece from the powdered, flame-retardant polyamide material which has not been consolidated by sintering or melting and solidification. Procedure according to Claim 1 or 2 , characterized in that - the polyamide material comprises one or more polyamides or a polymer blend of one or more polyamides with one or more miscible, compatible or immiscible polymers, which are selected in particular from polyolefins, polystyrenes, thermoplastic elastomers and polyacetals, the polyamide content in the polymer blend is at least 30% by weight, preferably at least 50% by weight, preferably at least 70% by weight, more preferably at least 90% by weight, and / or - the one or more phosphorus-containing compounds from a group can be selected, which includes: aromatic and aliphatic esters of phosphoric acid, such as resorcinol bis (diphenyl phosphate), bisphenol A bis (diphenyl phosphate) and their oligomers, triphenyl phosphate, tris (2-ethylhexyl) phosphate, tricresyl phosphate, isopropylated triphenyl phosphine, ethylenediamine , Ammonium phosphate, ammonium poly-phosphate, phosphinates, such as salts of the hypophosphorous Acid and its derivatives, such as alkylphosphinate salts, e.g. B. diethylene phosphinate aluminum or diethylene phosphinate zinc or aluminum phosphinate, aluminum phosphite, aluminum phosphate, phosphonate ester, oligomers and polymeric derivatives of methanephosphonic acid, 9,10-dihydro-9-oxa-10-phosphorylphenanthrene-10-oxide, ammonium poly-phosphate , Phosphacenes, vinylphosphonic acid, and / or - the one or more flame retardants based on melamine are selected from a group comprising: melamine, melamine derivatives, melamine condensation products, melamine salts, melem, melam, melon, benzoguanamine, allantoin, polyisocyanurates, melamine cyanurate, melamine phosphate, Dimelamine phosphate, melamine pyrophosphate, melamine polyphosphate, melamine metal phosphates such as melamine aluminum phosphate, melamine zinc phosphate, melamine magnesium phosphate, the corresponding pyrophosphates and polyphosphates, poly- [2,4- (piperazin-1,4-yl) -6- (morpholin-4-yl ) -1,3,5-triazine]. Method according to one of the preceding claims, characterized in that the polyamide material contains one or more polyamides selected from the group consisting of polyamide 6, polyamide 11, polyamide 12, polyamide 6.6, polyamide 6.9, polyamide 6.10, polyamide 6.12, polyamide 10.10 and copolyamides thereof, such as polyamide 6/12, PA 6.6 / 6.10, or consist of one or more of these polyamides. Method according to one of the preceding claims, characterized in that the polyamide material consists of polyamide 6 or polyamide 6 in a proportion of at least 30% by weight, preferably at least 50% by weight, preferably at least 70% by weight, more preferably at least Contains 90 wt .-%. Method according to one of the preceding claims, characterized in that the polyamide material contains, in addition to the flame retardant, further auxiliaries, in particular antistatic agents, dyes, such as soluble inorganic and / or organic pigments and / or insoluble dyes, fillers, such as glass fibers, Chalk, graphite, carbon black, lubricants, stabilizers and plasticizers can be selected. Method according to one of the preceding claims, characterized in that the flame retardant in a proportion in the range of 0.1 to 20 wt .-%, preferably 1 to 15 wt .-%, based on the total weight of the flame-retardant polyamide material in the polyamide material is introduced. Method according to one of the preceding claims, characterized in that the powdery, flame-retardant polyamide material has a particle size in particular in the range from 40 to 110 µm. Method according to one of the preceding claims, characterized in that one, several or all of the following steps are carried out for the provision of a powdery, flame-retardant polyamide material: - Production of a mixture or compounds from the polyamide material and the flame retardant, in particular in the form of a cast block or a granulate or a granular material produced in an extruder, - comminuting the block or the granulate or the granular material by mechanical processing, preferably grinding, particularly preferably cryogenic grinding, to a powdery material, and - sieving the powdery material to obtain a sieve fraction of the powdery material with the grain size distribution desired for the additive manufacturing, and - if necessary before or after the rounding off of the angular surface of the particles obtained after grinding from the powdery material. Method according to one of the preceding claims, characterized in that in step c) the radiation is a laser radiation, the wavelength of which - lies within the absorption band of the flame retardant, or - lies outside the absorption band of the flame retardant, or - lies on the long-wave side of visible light , or - is in the range of infrared radiation, or - is above 3000 nm, or - is emitted by an infrared laser, such as a CO ₂ laser, an Nd: YAG laser or a fiber laser. Method according to one of the preceding claims, characterized in that the laser energy radiated in step c) in the range from approximately 0.10 to 0.30 J / mm ³ , preferably approximately 0.15 to 0.25 J / mm ³ , in particular at is about 0.2 J / mm ³ . Flame-retardant workpiece that is manufactured using an additive manufacturing process according to one of the Claims 1 to 11 is available. Use of a flame-retardant polyamide material, which is as defined in one of the preceding claims and in particular in powder form, for additive manufacturing, in particular by selective laser sintering or selective laser melting, of a flame-retardant workpiece, in particular a flame-retardant workpiece with a high surface smoothness. Flame-retardant polyamide material, as defined in one of the preceding claims and in particular in powder form, for the additive manufacturing of a flame-retardant workpiece, in particular by selective laser sintering or selective laser melting. Flame retardant polyamide material Claim 14 , which is in powder form and is obtainable by: - preparing a mixture or compound or blend from the polyamide material and the flame retardant, in particular in the form of a cast block or a granulate or granular material produced in an extruder, - comminuting the block or the granulate or the granular material by mechanical processing, in particular grinding, preferably cryogenic grinding, to a powdery material, and - sieving the powdery material to obtain a sieve fraction of the powdery material with the grain size distribution desired for additive manufacturing, and - if necessary before or after rounding the angular surface of the particles of the powdery material obtained after grinding.

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