Thermoplastic polymer powder for 3D printing

Abstract

The present invention relates to a polymer powder for manufacturing articles by 3D printing, particularly by sintering, comprising a thermoplastic polymer, antioxidants, and a specific metal oxide, metal hydroxide, and / or hydrotalcite, having improved thermal stability, recyclability, and consistency of the mechanical properties of the sintered parts. The invention also relates to a process for preparing this powder, its use in a sintering manufacturing process, and articles manufactured from said powder.

Description

Title of the invention: Thermoplastic polymer powder for 3D printing. Field of the invention

[0001] The present invention relates to a polymer powder for the manufacture of articles by 3D printing, in particular by sintering, comprising a thermoplastic polymer, antioxidants, and a particular compound selected from a metal oxide, a metal hydroxide and / or a hydrotalcite, having improved thermal stability, recyclability and consistency of mechanical properties of sintered parts.

[0002] The invention also relates to a process for preparing this powder as well as its use in a manufacturing process by sintering, and articles manufactured from said powder. Technical background

[0003] There are various 3D printing techniques using polymer powder. The principle is generally based on the agglomeration of powder, layer by layer, by melting it (hereinafter "sintering") caused by electromagnetic radiation, for example one or more laser beams ("laser sintering"), infrared radiation, UV radiation, or any source of electromagnetic radiation that allows the powder to be melted layer by layer to manufacture three-dimensional objects.

[0004] One example is selective laser sintering (SLS). Another example is sintering technologies using an absorber, for example, the technologies known as High Speed ​​Sintering (HSS) and Multi-Jet Fusion (MJF).

[0005] For sintering processes, such as SLS or MJF, the use of thermoplastic polymer powder is preferred, for example a polyamide powder.

[0006] During each build by sintering process, also called a "run," a large portion of the powder is not used: for example, approximately 85% of the powder is not targeted by the laser in SLS or by the infrared in MJF and is therefore not agglomerated and / or not melted. It is therefore advantageous to be able to reuse, that is, recycle, this powder during the next build (or next "run").

[0007] However, during the sintering process, the presence of oxygen at high temperature can cause thermo-oxidative degradation of the polymer, inducing undesirable yellowing of the powder, which prevents the reuse of the powder non-agglomerated. A decrease in the inherent viscosity of the powders can also be observed due to their thermo-oxidative degradation; the resulting sintered parts may suffer a loss of mechanical properties. These thermo-oxidation phenomena also occur in so-called inert gas machines, where the oxygen content is indeed reduced, but oxygen is still present.

[0008] There is a continuing need to supply a thermoplastic polymer powder, having good thermal stability, for the manufacture of sintered parts having satisfactory mechanical properties and being recyclable.

[0009] For the purposes of the present invention, thermal stability means reduced thermo-oxidative degradation, namely, in particular limited yellowing (i.e. limited increase in YI) and / or a limited decrease in the inherent viscosity of the non-agglomerated powder during sintering.

[0010] It is known to use antioxidants in a powder formulation to improve the recyclability of the powder and / or to limit its yellowing.

[0011] Document FR 3087198 describes a powder for 3D printing based on a thermoplastic polymer, comprising a thioether antioxidant.

[0012] However, it turns out that the antioxidant effect of thioether is not always satisfactory. Indeed, yellowing of the powder has been observed during its processing in a 3D printing machine. Furthermore, an unpleasant sulfurous odor can be detected during its use and even after processing in the 3D printing machine.

[0013] US patent application 2004 / 0138363 describes a powder containing polyamide and titanium oxide particles. It describes that this powder has resistance to yellowing when exposed to thermal stress during 3D printing by laser sintering.

[0014] However, it turns out that the anti-yellowing effect of titanium oxide is not always satisfactory.

[0015] The present invention aims to provide a solution to one or more of the problems mentioned above.

[0016] More particularly, the invention aims to provide a thermoplastic polymer powder, preferably a polyamide powder, comprising antioxidants, and a metal oxide, a metal hydroxide, and / or a particular hydrotalcite, having improved thermal stability and thus better recyclability.

[0017] In the context of the present invention, a powder with improved thermal stability is understood to be a powder having a yellowness index (YI), measured after exposure in air at 177°C in a volume of approximately 50 mL for 72 hours, which is at least 20% lower than the index measured in the same conditions for the same powder without the presence of the particular metal oxide, metal hydroxide, and / or hydrotalcite. Summary of the invention

[0018] According to a first aspect, the present invention relates to a polymer powder suitable for 3D printing by sintering, comprising (a) a semi-crystalline thermoplastic polymer, (b) one or more antioxidants and (c) a metal oxide, a metal hydroxide, and / or a hydrotalcite derived from one or more alkaline earth metals, or from one or more poor metals, preferably from one or more poor metals.

[0019] The semi-crystalline thermoplastic polymer usable according to the invention can be chosen from: polyolefin, polyamide, polyester, polyarylether ketone, polyphenylene sulfide, polyacetal, polyimide, vinylidene fluoride polymer and / or their mixture, preferably a polyamide.

[0020] According to one embodiment, the metal oxide is chosen from ZnO and / or Al2O3.

[0021] It is preferable that component (c) be in powder form having a Dv suitable for 3D printing.

[0022] According to one embodiment, one or more antioxidants are chosen from one or more phenolic antioxidants, one or more phosphite / phosphonite antioxidants, one or more thioethers and / or mixtures thereof.

[0023] Thus, the powder of the present invention may comprise a mixture of phenolic and phosphite / phosphonite antioxidants, or of phenolic and thioether antioxidants, or of phosphite / phosphonite and thioether antioxidants, or even of phenolic and phosphite / phosphonite and thioether antioxidants.

[0024] Preferably, one or more antioxidants are chosen from one or more phenolic antioxidants, one or more thioethers and / or mixtures thereof.

[0025] According to one embodiment, the polymer powder further comprises fillers or reinforcements (d) and / or one or more additional additives (e).

[0026] It has been observed in the context of the present invention that the use of the metal oxide, metal hydroxide, and / or particular hydrotalcite, preferably in combination with one or more antioxidant(s) in a thermoplastic polymer powder suitable for 3D printing by sintering, made it possible to improve its thermal stability, while maintaining acceptable mechanical properties during successive builds.

[0027] More particularly, the addition of the metal oxide, metal hydroxide, and / or hydrotalcite as defined in the present invention, preferably in combination with one or more antioxidant(s) in a polymer powder suitable for Sintering printing allows for a very advantageous limitation of powder yellowing, during successive builds and / or on the printed part.

[0028] And in addition, a decrease in the unpleasant sulfurous odor during its use and even after transformation into a 3D printing machine was observed.

[0029] The present invention thus proposes a powder having excellent recyclability, even when the sintering process is carried out under severe conditions, typically in air, at high temperature (namely, generally a few degrees below the melting temperature) and / or for a prolonged duration in construction and / or when a large volume of parts is built.

[0030] Furthermore, and surprisingly, it has been observed that the addition of metal oxide, metal hydroxide, and / or hydrotalcite as defined in the present invention, preferably in combination with one or more antioxidants, makes it possible to obtain printed parts with improved mechanical properties throughout the production run, avoiding the production of parts with low elongation at break (generally those less than 10%). Indeed, compared to the same powder without the addition of metal oxide, metal hydroxide, and / or hydrotalcite as defined in the present invention, parts with low elongation are generally observed, which can generate significant quantities of parts with properties unsatisfactory for industrial-scale manufacturing.

[0031] According to one aspect, the invention relates to a method for preparing a powder as defined above.

[0032] The present invention also relates to the use of a metal oxide, a metal hydroxide, and / or a hydrotalcite derived from one or more alkaline earth metals, or from one or more poor metals, preferably from one or more poor metals, in a polymer powder suitable for 3D printing by sintering, to improve the thermal stability, in particular to limit the yellowing, of said powder.

[0033] The present invention also relates to the use of a metal oxide, a metal hydroxide, and / or a hydrotalcite derived from one or more alkaline earth metals, or from one or more poor metals, preferably from one or more poor metals, in a polymer powder suitable for 3D printing by sintering, to improve the mechanical property, in particular the elongation at break, of the printed parts made from said powder.

[0034] Preferably, the powder comprises one or more of one or more antioxidants, preferably selected from one or more phenolic antioxidants, one or more phosphite / phosphonite antioxidants, one or more thioethers and / or mixtures thereof.

[0035] Preferably, the metal oxide is chosen from ZnO and Al2O3.

[0036] The present invention also relates to a 3D printing process, preferably, a sintering process caused by electromagnetic radiation, using the powder as defined above, or a powder comprising a portion of said powder not agglomerated and recovered after one or more builds within the same printing process or a different printing process.

[0037] Preferably, the electromagnetic radiation is chosen from one or more laser beams, infrared radiation or UV radiation, with or without an absorber.

[0038] The present invention also relates to an article obtained by the 3D printing process as defined above.

[0039] The article can be chosen from prototypes, models and parts, in particular in the fields of automotive, nautical, aeronautical, aerospace, medical (prostheses, hearing systems, cellular tissues...), textiles, clothing, fashion, decoration, design, housings for electronics, telephony, computer science, lighting, sports, industrial tools.

[0040] Preferably, the inherent viscosity in solution (also called "inherent viscosity") of the printed part is greater than 0.8, so that the article exhibits acceptable mechanical properties. More preferably, the inherent viscosity of the printed part is greater than 1.0. Generally, the inherent viscosity of the printed part is less than 4.0, preferably less than 3.0.

[0041] The invention is now described in detail and in a non-limiting manner in the following description. Description of the invention Definition

[0042] In the present description of the invention, including in the examples below.

[0043] The Dv50, also referred to herein as the "median volume diameter," corresponds to the particle size value that divides the examined particle population exactly in half. The Dv50 is measured according to ISO 13320-1. In this description, a Malvern Insitec particle size analyzer and RTSizer software are used to obtain the particle size distribution of the powder and deduce the Dv50.

[0044] The inherent viscosity in solution (in particular of polyamide, polyamide powders or parts manufactured by sintering from them) is measured according to the following steps: - Sampling of polymer samples weighing between 0.07 and 0.10 g, and preferably a maximum of 0.15 g, - Addition of a sufficient quantity of m-cresol solvent by weighing in order to obtain a concentration (C) of 0.5 g / L, - Heating the mixture under stirring on a hot plate, regulated at 100°C ± 5°C, until complete dissolution of the polymer; - Cooling the solution to room temperature, preferably for at least 30 minutes; - Measurement of the flow time t0 of the pure solvent and the flow time t of the solution using a micro-Ubbelohde tube viscometer in a thermostatically controlled bath regulated at 20°C ± 0.05°C, - Calculation of viscosity according to the formula 1 / C x Ln (t / tO), where C represents the concentration and Ln the natural logarithm, For each sample, three measurements are taken on different solutions and then the average is calculated.

[0045] The thermal characteristics of the polyamide are analyzed by DSC according to ISO 11357-3 "Plastics - Differential Scanning Calorimetry (DSC) Part 3: Determination of temperature and enthalpy of melting and crystallization". The temperatures of particular interest to the invention are the melting temperature upon first heating (Tfl), the crystallization temperature (Te), and the enthalpy of fusion.

[0046] By "semi-crystalline thermoplastic polymer" is meant a thermoplastic polymer that exhibits: a crystallization temperature (Te) determined according to ISO 11357-3:2013, during the cooling step at a rate of 20K / min in DSC (differential scanning calorimetry); - a melting temperature (Tf) determined according to ISO 11357-3:2013 during the heating step at a speed of 20 K / min in DSC; and - and an enthalpy of fusion (AHf) determined according to ISO 11357-3:2013 during the heating step at a speed of 20 K / min in DSC, which is greater than 5 J / g, for example greater than 10 J / g, preferably greater than 20 J / g and is generally less than 205 J / g, preferably less than 150 J / g.

[0047] Yellowing is quantified by the yellowness index (YI) measured according to ASTM E313-96 (D65), in particular using a Konica Minolta spectrocolorimeter illuminating D65 under 10° in included specular reflection (SCI) mode.

[0048] The mechanical properties, in particular the tensile modulus and the elongation at break, are measured according to ISO 527-IB: 2012.

[0049] In the present description, it is specified that when reference is made to intervals, expressions of the type "between... and..." include the bounds of the interval.

[0050] Unless otherwise stated, the percentages expressed are mass percentages. Unless otherwise stated, the parameters referred to are measured at atmospheric pressure and ambient temperature (23°C).

[0051] The nomenclature used to designate polyamides follows ISO 1874-1:2011. The term "monomer" in this description of polyamides should be understood as "repeating unit." In particular, in the notation PA "XY" designating a polyamide resulting from the condensation of a diamine with a dicarboxylic acid, X represents the number of carbon atoms of the diamine and Y represents the number of carbon atoms of the dicarboxylic acid. In the notation PA "Z," Z represents the number of carbon atoms of the polyamide units resulting from the condensation of an amino acid or lactam. The notation PA X / Y, PA X / Y / Z, etc. (referred to in the context of the invention as PA "X / Y") refers to copolyamides in which X, Y, Z, etc., represent homopolyamide units X, Y, Z as described in the present invention. Semi-crystalline thermoplastic polymer

[0052] The semi-crystalline thermoplastic polymer of the present invention has an enthalpy of fusion (AHf) determined according to ISO 11357-3:2013 during the heating step at a speed of 20 K / min in DSC, which is greater than 5 J / g.

[0053] The semi-crystalline thermoplastic polymer usable according to the invention can be chosen from: polyolefin, polyamide, polyester, polyarylether ketone, polyphenylene sulfide, polyacetal, polyimide, vinylidene fluoride polymer and / or their mixture, preferably a polyamide.

[0054] Preferably, the semi-crystalline thermoplastic polymer is a polyamide.

[0055] The polyamide can be a homopolyamide (i.e. PA “XY” and PA “Z”), a copolyamide (i.e. PA “X / Y”), or mixtures thereof.

[0056] “Z” type polyamides are derived from the condensation of one or more α,co-aminocarboxylic acids and / or one or more lactams.

[0057] As an example of an α,co-amino carboxylic acid, one can cite the alpha-omega amino acids, such as aminocaproic, amino-7-heptanoic, amino-11-undecanoic, n-heptyl-11-aminoundecanoic and amino-12-dodecanoic.

[0058] Examples of lactams include those having 3 to 12 carbon atoms on the main ring and which can be substituted. Examples include [3,[3-dimethylpropriolactam, α,α-dimethylpropriolactam, amylolactam, caprolactam, capryllactam, oenantholactam, 2-pyrrolidone and lauryllactam.

[0059] As an example of this type of preferred polyamides, we can cite PA 6, PA 11 and PA 12.

[0060] Polyamides of the "XY" type are obtained from the condensation of a dicarboxylic acid with an aliphatic, cycloaliphatic or aromatic diamine.

[0061] As an example of a diamine, one can cite aliphatic diamines having from 6 to 12 atoms, the diamine X being able to be also aryl and / or saturated cyclic. Examples include hexamethylenediamine, piperazine, tetramethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, 1,5-diaminohexane, 2,2,4-trimethyl-1,6-diaminohexane, diamine polyols, isophoronediamine (IPD), methyl pentamethylenediamine (MPDM), bis(aminocyclohexyl)methane (BACM), bis(3-methyl-4-aminocyclohexyl)methane (BMACM), methaxylyenediamine, trimethylhexamethylenediamine. Examples of dicarboxylic acids include acids with between 4 and 18 carbon atoms, preferably from 9 to 12 carbon atoms. Examples include adipic acid, sebacic acid, azelaic acid, suberic acid, isophthalic acid, butanedioic acid, 1,4-cyclohexyldicarboxylic acid, terephthalic acid, the sodium or lithium salt of sulfoisophthalic acid, dimerized fatty acids (especially those with a dimer content of at least 98% and / or hydrogenated) and 1,2-dodecanedioic acid HOOC-(CH2)iO-COOH.

[0062] By way of example of this type of preferred polyamides, PA 612 resulting from the condensation of hexamethylene diamine and 1,12-dodecanedioic acid; PA 613 resulting from the condensation of hexamethylene diamine and brassylic acid; PA 912 resulting from the condensation of 1,9-nonanediamine and 1,12-dodecanedioic acid; PA 1010 resulting from the condensation of 1,10-decanediamine and sebacic acid; PA 1012 resulting from the condensation of 1,10-decanediamine and 1,12-dodecanedioic acid.

[0063] The polyamide can also be a copolyamide resulting from the condensation of: - at least two different monomers, for example at least two different α,co-amino carboxylic acids or - two different lactams or - of a lactam and an α,co-amino carboxylic acid with a different number of carbon atoms or -of at least one α,co-amino carboxylic acid (or a lactam), at least one diamine and at least one dicarboxylic acid, or - of an aliphatic diamine with an aliphatic dicarboxylic acid and at least one other monomer chosen from aliphatic diamines different from the previous one and aliphatic diacids different from the previous one.

[0064] Polyamide mixtures can also be used, which may be mixtures of aliphatic polyamides and semi-aromatic polyamides and mixtures of aliphatic polyamides and cycloaliphatic polyamides.

[0065] The polyamide of the present invention may also be a polyamide-polyether block copolymer (PEBA) or a mixture of a polyamide-polyether block copolymer with at least one of the aforementioned polyamides.

[0066] PEBA copolymers can result from the copolycondensation of reactive-end polyamide blocks with reactive-end polyether blocks, such as, among others: 1) polyamide blocks with diamine chain ends with polyoxyalkylene blocks with dicarboxylic chain ends; 2) polyamide blocks with dicarboxylic chain ends with polyoxyalkylene blocks with diamine chain ends; 3) polyamide blocks with dicarboxylic chain ends with polyetherdiols, the products obtained being, in this particular case, polyetheresteramides.

[0067] The polyamide blocks can be a homopolyamide or a copolyamide as described above for homopolyamides and copolyamides.

[0068] Polyamide blocks with dicarboxylic acid chain ends are obtained, for example, from the condensation of polyamide precursors in the presence of a dicarboxylic acid chain limiter. Polyamide blocks with diamine chain ends are obtained, for example, from the condensation of polyamide precursors in the presence of a diamine chain limiter.

[0069] The PEBA polyether blocks can be derived from alkylene glycols such as PEG (polyethylene glycol), PPG (propylene glycol), PO3G (polytrimethylene glycol) or PTMG (polytetramethylene glycol), preferably PTMG.

[0070] Polymers with polyamide and polyether block structures may include randomly distributed motifs. These polymers may be prepared by the simultaneous reaction of the polyether and the precursors of the polyamide blocks.

[0071] Polyetherdiol blocks are either used as is and copolycondensed with carboxyl-ended polyamide blocks, or they are amineized to be transformed into polyetherdiamines and condensed with carboxyl-ended polyamide blocks. They can also be mixed with polyamide precursors and a chain limiter to make polymers with polyamide and polyether blocks having statistically distributed motifs.

[0072] The ratio of the quantity of polyamide block copolymer and polyether block copolymer to the quantity of polyamide is advantageously between 1 / 99 and 15 / 85 by weight.

[0073] As regards the mixture of polyamide and at least one other polymer, it is in the form of a polyamide matrix mixture and the other polymer(s) form(s) the dispersed phase. Examples of this other polymer include polyolefins, polyesters, polycarbonate, PPG (polyphenylene oxide), PPS (polyphenylene sulfide), and elastomers.

[0074] Preferably, the powders comprise at least one polyamide selected from the following PEBA polyamides, copolyamides and / or copolymers comprising at least one of the following XY or Z monomers: 46, 4T, 54, 59, 510, 512, 513, 514, 516, 518, 536, 6, 64, 66, 69, 610, 612, 613, 614, 616, 618, 636, 6T, 9, 104, 109, 1010, 1012, 1013, 1014, 1016, 1018, 1036, 10T, 11, 12, 124, 129, 1210, 1212, 1213, 1214, 1216, 1218, 1236, 12T, MXD6, MXD10, MXD12, MXD14, and their mixtures; in particular selected from PA 6, PA 11, PA 12, PA 612, PA 613, PA 912, PA 1010, PA1012 6, PA 6 / 12, PA 11 / 1010, and their mixtures. Antioxidants

[0075] Component (b) according to the invention is selected from one or more phenolic antioxidants, one or more phosphite / phosphonite antioxidants, one or more thioethers and / or mixtures thereof. Phenolic antioxidant

[0076] According to one embodiment, the powder of the invention comprises a phenolic antioxidant, such as: - 3,3'-Bis(3,5-di-tert-butyl-4-hydroxyphenyl)-N,N'-hexamethylenedipropionamide, marketed notably under the name Palmarole AO.OH.98 by Palmarole, - (4,4'-Butylidenebis(2-t-butyl-5-methylphenol), marketed notably under the name Lowinox® 44B25 by Addivant, - Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), marketed notably under the name Irganox® 1010 by BASF, - N,N'-hexane-1,6-diylbis(3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)), marketed notably under the name Irganox® 1098 by BASF, - 3,3',3',5,5',5'-hexa-tert-butyl-α,α',α'-(mesitylene-2,4,6-triyl)tri-p-cresol, marketed notably under the name Irganox® 1330 by BASF, - ethylenebis(oxyethylene)bis-(3-(5-tert-butyl-4-hydroxy-β-tolyl)propionate), marketed notably under the name Irganox® 245 by BASF, -l,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-l,3,5-triazine-2,4,6(lH,3H, 5H)-trione marketed notably under the name Irganox® 3114 by BASF, - N'N'-(2-ethyl-2'-ethoxyphenyl)oxanilide, marketed notably under the name Tinuvin® 312 by BASF, - 4,4',4"-trimethyl-1,3,5-benzenetriyl) tris-(methylene)] tris 2,6-bis(l, 1-dimethylethyl)phenol marketed notably under the name Alvinox® 1330 by 3V, Hostanox® 245 FF, Hostanox® 245 Pwd, marketed by Clariant, - pentaerythritol tetrakis (3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) marketed notably under the names Evemox® 10, Evernox® 10GF, by Everspring Chemical Company Limited, - octadecyl-3-(3,5-di-tert-4-hydroxyphenyl)-propionate, marketed notably under the names Evernox® 76 and Evemox® 76GF by Everspring Chemical Company Limited, - tetrakis [methylene-3(3',5'-di-tert-butyl-4-hydroxyphenyl) propionate] methane, marketed notably under the name BNX® 1010 by Mayzo, - thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] marketed notably under the name BNX® 1035 by Mayzo, - tetrakis [methylene-3 (3',5'-di-tert-butyl-4-hydroxyphenyl)propionate] methane, - octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate, marketed notably under the name BNX® 2086 by Mayzo, and - the 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)trione marketed notably under the name BNX® 3114 by Mayzo. Phosphite / phosphonite antioxidant

[0077] According to one embodiment, the powder comprises phosphite / phosphonite antioxidants including aromatic or aliphatic phosphonites, such as the product Hostanox® P-EPQ® marketed by Clariant, alkali salts of phenylphosphonic acid or hypophosphorous acid, compounds including phosphite functions, such as trialkyl- and trialkylaryl-phosphites and cyclic diphosphites derived from pentaerythritol, for example, Irgafos® 168 marketed by BASF.

[0078] Examples of trialkyl- and trialkylaryl-phosphites include trinonyl-, tri(nonylphenyl)-, and tri[(2,4-di-tert-butyl-5-methyl)phenyl] phosphites. An example of cyclic diphosphites derived from pentaerythritol is distearylpentaerythritol diphosphite. Thioether

[0079] According to one embodiment, the thioether is selected from: dilauryl thiodipropionate (DLTDP), ditridecyl thiodipropionate (DTDTDP), distearyl thiodipropionate (DSTDP), dimyristyl thiodipropionate (DMTDP), pentaerythritol tetrakis (3-dodecylthiopropionate or 3-laurylthiopropionate), 3,3'-thiodipropionate, alkyl (C12-14) thiopropionate, dilauryl 3,3'-thiodipropionate, ditridecyl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, dioctadecyl 3,3'-thiodipropionate, lauryl stearyl 3,3-thiodipropionate, tetrakis[methylene 3-(dodecylthio)propionate] methane, thiobis(2-tert-butyl-5-methyl-4,l-phenylene)bis(3-(dodecylthio)propionate), 2,2'-thiodiethylene bis(3-aminobutenoate), 4,6-bis(octylthiomethyl)-o-cresol, 2,2'-thiodiethylene bis 3-(3,5-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-thiobis(4-methyl 6-tert-butyl-phenol), 2,2'-thiobis(6-tert-butyl-p-cresol), 4,4'-thiobis (6-tert-butyl-3-methylphenol), 4,4'- thiobis (4-methyl 6-tert-butyl phenol), bis(4,6-tert-butyl-l-yl-2-) sulfide, tridecyl-3,5-di-tert-butyl-4-hydroxybenzyl thioacetate, l,4-bis(octylthiomethyl)-6-phenol, 2,4-bis (dodecylthiomethyl)-6-methylphenol, distearyl-disulfide, bis (methyl-4-3-n-alkyl (C12 / C14) thiopropionyloxy 5-tert-butylphenyl) sulfide and / or mixtures thereof.

[0080] Preferably, the thioether is selected from the group consisting of dilauryl thiodipropionate (DLTDP), ditridecyl thiodipropionate (DTDTDP), distearyl thiodipropionate (DSTDP), dimyrystil thiodipropionate (DMTDP), pentaerythritol tetrakis (3-dodecylthio propionate or 3-laurylthiopropionate), and / or mixtures thereof.

[0081] According to one embodiment, the thioether is the DLTDP.

[0082] According to one embodiment, the thioether is the DSTDP.

[0083] Preferably, the thioether is pentaerythritol tetrakis (3-dodecylthio propionate). Such a compound is notably marketed by the companies Songnox, or Adeka under the trade name ADK ST AB AO-412S.

[0084] Preferably, the thioether has a melting point less than or equal to 180°C, preferably less than or equal to 160°C, preferably less than or equal to 140°C, even more preferably less than or equal to 130°C, or 100°C.

[0085] Metal oxide / metal hydroxide / hydrotalcite

[0086] Component (c) of the present invention is selected from a metal oxide, a metal hydroxide, and / or a hydrotalcite derived from one or more alkaline earth metals, or from one or more poor metals, preferably from one or more poor metals.

[0087] According to one embodiment, component (c) is a hydrotalcite derived from one or more alkaline earth metals, or from one or more poor metals, preferably from one or more poor metals.

[0088] The hydrotalcite according to the invention can typically be of the formula Ma2+ Mb3+(OH)2a+2b IX )b Zi, yH2O in which Ma2+ represents divalent metal ions, Mb3+ represents trivalent metal ions and X1 represents an anion, typically a carbonate or a nitrate.

[0089] For example, a hydrotalcite usable in the powder of the invention can be a Mg6Al2CO3(OH)16-4(H2O).

[0090] According to one embodiment, component (c) is derived from one or more alkaline earth metals, i.e. the metals of the second group of the periodic table.

[0091] Preferably, the alkaline earth metals are chosen from magnesium, calcium, strontium and / or barium.

[0092] According to one embodiment, component (c) is derived from one or more base metals.

[0093] By “poor metals” is meant a metallic chemical element located, in the periodic table, between the transition metals on their left and the metalloids on their right.

[0094] Preferably, the base metals are chosen from aluminium, gallium, indium, zinc, and / or tin, preferably chosen from zinc and / or aluminium.

[0095] Preferably, component (c) is chosen from ZnO and / or Al2O3. Polymer powder

[0096] According to one embodiment, the polymer powder according to the invention comprises a thermoplastic polymer (a), a thioether (b), a metal oxide, a metal hydroxide, and / or a hydrotalcite derived from one or more alkaline earth metals, or from one or more lean metals, preferably from one or more lean metals (c), fillers or reinforcements (d) and / or one or more additional additives (e).

[0097] According to one embodiment, the powder according to the invention comprises: (a) 36 to 99.9%, preferably 40 to 95%, by weight of a thermoplastic polymer; (b) 0.1 to 2%, preferably 0.5 to 1%, by weight of one or more antioxidant(s); (c) 0.05 to 2%, preferably 0.1 to 1% by weight of a metal oxide, a metal hydroxide, and / or a hydrotalcite; (d) 0 to 50%, preferably 10 to 50%, and in particular 20 to 40% by weight of loads or reinforcements; and (e) 0 to 10%, preferably 0.1 to 7.5%, in particular 1 to 5% by weight of additional additives, the respective proportions of components (a), (b), (c), (d) and (e) adding up to 100%.

[0098] Component (e) may include one or more of these additives.

[0099] Preferably, the polymer powder has a first melting point of heating (Tfl) between 80 and 220°C, preferably between 100 and 200°C.

[0100] The powder can have a crystallization temperature (Te) of 40 to 250°C, and preferably of 45 to 200°C, for example of 60 to 170°C.

[0101] When dealing with a mixture of polymers (a), we consider Tf to be the lowest Tf in the mixture, and Te to be the highest Te in the mixture.

[0102] The difference between the Te and the Tf of the powder is preferably greater than or equal to 20°C, or preferably even greater than or equal to 30°C.

[0103] According to one embodiment, the inherent viscosity in solution of the powder before its use in a sintering process is typically less than 3, preferably less than 2.

[0104] Preferably, the inherent viscosity of the powder, unaffected by electromagnetic radiation after initial construction in a sintering process, is between 0.8 and 3, preferably between 1 and 2.

[0105] Typically, the polymer powder according to the invention has a diameter Dv50 of 40 to 150 pm, and preferably of 40 to 100 pm. For example, the diameter Dv50 of the polymer powder may be 40 to 45 pm; or 45 to 50 pm; or 50 to 55 pm; or 55 to 60 pm; or 60 to 65 pm; or 65 to 70 pm; or 70 to 75 pm; or 75 to 80 pm; 80 to 85 pm; or 85 to 90 pm; or 90 to 95 pm; or 95 to 100 pm; or 100 to 105 pm; or 105 to 110 pm; or from 110 to 115 pm; or from 115 to 120 pm; or from 120 to 125 pm; or from 125 to 130 pm; or from 130 to 135 pm; or from 135 to 140 pm; or from 140 to 145 pm; or from 145 to 150 pm. Charges and reinforcements

[0106] The polymer powder according to the invention may optionally include fillers or reinforcements, particularly to ensure that the printed article exhibits sufficient mechanical properties, especially in terms of modulus. These fillers may include, in particular, carbonate minerals, notably calcium carbonate, magnesium carbonate, dolomite, calcite, barium sulfate, calcium sulfate, dolomite, alumina hydrate, wollastonite, montmorillonite, zeolite, pearlite, nanofillers (fillers with dimensions on the order of nanometers) such as nano-clays, calcium silicates, magnesium silicates, such as talc, mica, kaolin, attapulgite, and mixtures thereof. Examples of reinforcements include, in particular, carbon nanotubes, glass powder, glass fibers and carbon fibers, as well as solid or hollow glass beads, optionally coated with silane.Component (d) may include one or more fillers and / or reinforcements. Advantageously, the fillers and reinforcements do not include pigments as defined above for pigment composition.

[0107] More specifically, the powder of the invention may comprise 0 to 50%; or 5 to 50%; or 10 to 40%; or 10 to 30% by weight of component (d). In one embodiment, the polymer powder is free of fillers and reinforcements. Additional additives

[0108] The polymer powder may, where appropriate, include additional additives (e) commonly used in polymer powders used in 3D printing by sintering.

[0109] This may include additives, in powder form or otherwise, which contribute to improving the behavior of the powder in 3D printing by sintering and those which improve the properties of the printed articles, in particular mechanical strength, thermal strength, fire resistance, and in particular elongation at break and impact resistance.

[0110] These common additives may be selected from among flow agents, chain restrictors, fire retardants, flame retardants, UV stabilizers, abrasion inhibitors, light stabilizers, shock modifiers, antistatic agents, pigments and waxes. Flow agent

[0111] By way of example, the flow agent may be chosen from silicas, in particular hydrophobic fumed silica, for example, the product marketed under the name Cab-o-Sil® TS610 by Cabot Corporation, precipitated silica, hydrated silica, vitreous silica, fumed silica, vitreous oxides, in particular vitreous phosphates, vitreous borates, alumina, such as amorphous alumina, and mixtures thereof. Pigments

[0112] The pigment can be, for example for HSS or MJF technology, a pigment having an absorbance of light at a wavelength of 1000 nm, as measured according to ASTM E1790, of less than 40%. Wax

[0113] The wax may comprise polyethylene and polypropylene wax, polytetrafluoroethylene, ketones, acid, partially esterified acid, acid anhydride, ester, aldehydes, amides, their derivatives, and mixtures thereof. The wax may, in particular, comprise a product marketed under the name Crayvallac® WN1135, WN 1495, or WN1265 by ARKEMA or a product marketed under the name Ceridust® 9615A or 8020 by CLARIANT.

[0114] According to one embodiment, the wax is present in the powder in the form of a coating covering at least partially the polymer powder. Chain limiter

[0115] The powder of the invention may include a chain limiter selected from dicarboxylic acids, monocarboxylic acids, diamines and monoamines, each of which may be linear or cyclic.

[0116] Preferably, the chain limiter has a melting point below 180°C.

[0117] The monocarboxylic acid preferably has from 2 to 20 carbon atoms. Examples of monocarboxylic acids include acetic acid, propionic acid, benzoic acid, stearic acid, lauric acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, hexadecanoic acid, octodecanoic acid, and tetradecanoic acid.

[0118] The dicarboxylic acid preferably has from 2 to 20 carbon atoms, more preferably from 6 to 10 carbon atoms. As an example of a diacid Examples of carboxylic acids include sebacic acid, adipic acid, azelaic acid, suberic acid, dodecanedicarboxylic acid, butanedioic acid, and orthophthalic acid.

[0119] Monoamine can be, in particular, a primary amine having from 2 to 18 carbon atoms. Examples of monoamines include 1-aminopentane, 1-aminohexane, 1-aminoheptane, 1-aminooctane, 1-aminononane, 1-aminodecane, 1-aminoundecane, 1-aminododecane, benzylamine, and oleylamine.

[0120] The diamine may in particular be a primary diamine comprising 4 to 20 carbon atoms. Examples of diamines include the isomers of bis-(4-aminocyclohexyl)methane (BACM), bis-(3-methyl-4-aminocyclohexyl)methane (BMACM), and 2-2-bis-(3-methyl-4-aminocyclohexyl)-propane (BMACP), and para-amino-di-cyclo-hexyl-methane (PACM), isophoronediamine (IPDA), 2,6-bis-(aminomethyl)-norbornane (BAMN) and piperazine.

[0121] According to one embodiment, the chain limiter represents from 0.01 to 10%, preferably 0.01 to 5%, preferably from 0.01 to 4%, preferably from 0.01 to 3%, preferably from 0.01 to 2%, preferably from 0.01 to 1% by weight relative to the total weight of the thermoplastic polymer, or relative to the total weight of the polyamide when the thermoplastic polymer is a polyamide.

[0122] The chain limiter can represent from 0.01 to 2% by weight relative to the total weight of the thermoplastic polymer, or relative to the total weight of the polyamide when the thermoplastic polymer is a polyamide.

[0123] Preferably, the chain limiter represents 0.01 to 0.5%, 0.01 to 0.4%, 0.01 to 0.3%, 0.01 to 0.2% by weight relative to the total weight of the thermoplastic polymer, or relative to the total weight of the polyamide when the thermoplastic polymer is a polyamide. Polymer powder preparation process

[0124] The polymer powder can be manufactured using the usual methods.

[0125] For component (a), commercially available thermoplastic polymers, in particular in the form of granules, flakes or powder, or synthesized thermoplastic polymers may be used.

[0126] If necessary, component (a) can be transformed into powder, using known processes, in particular by grinding.

[0127] The grinding can be ambient temperature grinding.

[0128] The grinding can be cryogenic grinding. In this process, the material to be ground is cooled, for example by means of liquid nitrogen, liquid carbon dioxide or liquid helium, to make the material easier to grind.

[0129] Grinding can be carried out for example in a counter-rotating pin mill, a hammer mill or a whirl mill.

[0130] According to one embodiment, the process for preparing a powder according to the invention comprises one or more of the following steps: (i) synthesis of a thermoplastic polymer (a), (ii) grinding the thermoplastic polymer (a) into a powder with a diameter Dv50 of 40 to 150 pm, (iii) introduction of one or more antioxidant(s) (b), and of a metal oxide, a metal hydroxide, and / or a hydrotalcite (c), and where appropriate of one or more components (d) to (e), before or after step (ii).

[0131] The introduction of some or all of the components (b) to (e) into the thermoplastic polymer (component (a)) can be carried out according to methods known to the person skilled in the art.

[0132] By way of example, introduction can be carried out by mixing in the molten state, for example by extrusion (compounding) and, where appropriate, granulation followed by grinding of the granules. Introduction can be carried out by wet impregnation (reference may be made, for example, to the method described in EP 3 325 535 Bl). Alternatively, it is also possible to carry out introduction by dry blending.

[0133] According to one embodiment, the introduction step can be carried out during the synthesis of the thermoplastic polymer.

[0134] For example, it is possible to mix the components by means of coprecipitation of the polymer (a) with a solution in the presence of some or all of the components (b) to (e) (dissolution / precipitation). The conditions can be easily adapted by those skilled in the art. Reference may be made, for example, to document EP 0863174 BL

[0135] It is also possible to mix some or all of the components (b) to (e) with a prepolymer of component (a), during or after the synthesis of the prepolymer.

[0136] Thus, according to one embodiment, the process for preparing a powder of the invention comprises the steps of: (i) prepolymerization of the monomer(s) of the thermoplastic polymer (a); (ii) grinding into a powder; (iii) subjecting the resulting prepolymer powder to solid-phase polycondensation to obtain a polymer powder, (iv) introduction of one or more antioxidant(s) (b), a metal oxide, a metal hydroxide, and / or a hydrotalcite (c), where appropriate one or more components (d) to (e) to the prepolymer powder, by melt mixing or dry mixing, between step (i) and (ii) and / or (ii) and (iii), and / or subsequently, by dry mixing.

[0137] It is also possible to use several of these processes, depending on the additives, for their introduction into the polymer powder.

[0138] The powder thus obtained can then be sieved or subjected to a selection step to obtain the desired particle size profile.

[0139] Depending on a certain method of preparation, the polymer powder may, where appropriate, be subjected to different treatments, in particular thermal or hydraulic treatments.

[0140] The components can be used in any suitable form according to the preparation method.

[0141] According to one embodiment, one or more components are used in powder form. The shape and size of the particles forming the powder are not particularly limited, except by the application of 3D printing by sintering. The particles are most often spherical. However, their use in other forms, such as rods or lamellar forms, is not excluded.

[0142] When the components are added to the polymer by dry blending, they advantageously have a volume median diameter Dv50 substantially equal to or less than that of the powder with which they will be blended. More specifically, the volume median diameter Dv50 of the components is preferably between 0.01 and 50 pm, preferably between 0.05 and 30 pm, even more preferably between 0.1 and 20 pm, in particular between 0.2 and 10 pm, and especially between 0.5 and 5 pm.

[0143] The invention will be further explained in a non-limiting manner with the help of the following Examples. Examples

[0144] The examples below illustrate the present invention without limiting its scope. In the examples, unless otherwise indicated, all percentages and parts are expressed by weight.

[0145] Although the tests refer to a powder based on polyamide 11, it is understood that the powders according to the present invention are not limited to this embodiment, but may include any type of polymer, in particular polyamide, alone or in mixture.

[0146] The base powder used is a powder comprising one hundred parts by weight of polyamide 11, added with the different components as described above.

[0147] A low viscosity polyamide 11, referred to hereafter as "prepolymer", was synthesized from amino-11-undecanoic acid in the presence of water, hypophosphorous acid and phosphoric acid.

[0148] The polyamide lia powder was then prepared by grinding this prepolymer, and then subjecting said prepolymer to a hydraulic treatment according to the process described in EP 1413595A, followed by solid-phase polycondensation. During solid-phase polycondensation, the antioxidants were added.

[0149] The polyamide powder binds an inherent viscosity equal to 1.20 (20°C, in 0.5% mass solution in metacresol).

[0150] The metal oxides and the flow agent were added to the powder by dry mixing in a Henschel IAM 6L mixer where the compounds to be mixed are introduced in the proportions indicated in Table 1 below and are stirred at 900 rpm for 100s at room temperature.

[0151] The Dv50 of the measured powder is 50 pm.

[0152] [Tables 1 Ex. PA (100% by weight) Phenolic antioxidant (PHR) Flow agent (PHR) Thioether (PHR) Metal oxide (PHR) PTDP DST DP ZnO Al2 O3 TiO 2 1 (comparative) 100 0.4 0.13 0.5 - - - - 2 (comparative) 100 0.4 0.13 - 0.5 - - - 3 100 0.4 0.13 0.5 - 0.15 - - 4 100 0.4 0.13 0.5 - - 0.15 - 5 100 0.4 0.13 - 0.5 0.13 - - 6 100 0.4 0.13 - 0.5 - 0.13 - 7 (comparative) ative) 100 0.4 0.13 0.5 - - - 0.15

[0153] PHR = parts per hundred of resin, said parts per hundred of resin (unit of measurement used in formulation designating the number of parts of a constituent per hundred parts of base powder by mass).

[0154] PTDP is a pentaerythritol tetrakis (3-dodecylthio propionate).

[0155] DSTDP is a distearyl thiodipropionate.

[0156] Flow agent: hydrophobic fumed silica • Aging test and measurement of the yellow index (YI) of the powder

[0157] a) In solid

[0158] The test consists of exposing the powder from the examples to 177°C in a glass flask placed in an air-ventilated oven for 72 hours. The results were shown in Table 3.

[0159] This test simulates the exposure conditions that a powder may undergo in a 3D machine. The measurements of the yellow index (YI) are made using a Konica Minolta spectrocolorimeter illuminating D65 under 10° in included specular reflection (SCI) mode according to ASTM standard YI (E313-96) (D65).

[0160] b) In fade

[0161] The test consists of exposing the powder of the examples to 220°C, in an aluminium cup placed in an air-ventilated oven, for 2 hours.

[0162] Next, the melted film is peeled off and the measurement is taken by placing it in front of a Leneta Form 2A opacity plate. The results are shown in Table 3.

[0163] This test simulates the exposure conditions that a part may undergo in a 3D machine during its construction.

[0164] The measurements of the yellow index (YI) are made on a Konica Minolta spectrocolorimeter illuminating D65 under 10° in SCI mode according to the ASTM YI (E313-96) (D65) standard.

[0165] [Tables2] Ex. YI to ASTM YI (E313-96) (D65). in SCI (solid test) YI (72h 177°C in air) ASTM YI (E313-96) (D65) in SCI (solid test) YI (2h at 220°C in air) ASTM YI (E313-96) (D65) in SCI (molten test) 1 (comparative) 2 25 69 2 (comparative) 2 29 86 3 2 14 42 4 2 18 51 5 2 20 55 6 2 22 59 7 (comparative) 2 33 74

[0166] During solid and molten aging tests, it was observed that the yellow index values ​​are lower for a powder containing a thioether and a metal oxide (e.g., 3 to 6) compared to a powder without the thioether and metal oxide (e.g., 1 and 2) and compared to a powder where the metal oxide is TiO2. Thus, the use of thioether and the metal oxide ZnO and / or Al2O3 in a polyamide powder improved the color stability of both the powder and the printed part. • Elongation test at break

[0167] The polymer powder thus obtained is then used to print test specimens with ISO 527-1A geometry. These specimens are built along the Z-axis (vertical axis, [Fig. 1]) in an HP MJF5200 machine commercially available and configured. The conditions used are the same for all prints.

[0168] The model below was prepared using the software Materialized Magies 22.0.

[0169] The test specimens were then constructed according to this model shown in [Fig. 1].

[0170] During construction, the temperature of the powder at the surface of the construction tray is imposed and measured at the surface using an infrared thermal sensor.

[0171] The construction time of the two test specimen blocks is approximately 12 hours and they are allowed to cool at room temperature for 48 hours.

[0172] The test specimens of the lower block were constructed first. They were therefore subjected to thermo-oxidation for a longer period.

[0173] The lower block specimens thus obtained are then characterized with regard to their mechanical properties. More specifically, the elongation at break of the specimens is measured on an INSTRON 5966 machine according to ISO 527-2.

[0174] [Fig.2] represents the percentage of test specimens having an elongation greater than x%, x being the x-coordinate of the graph.

[0175] Compared to the same powder without the addition of a metal oxide (powder of Comparative Example 1), the rate of specimens having an elongation < 10% is higher.

[0176] It is also observed that the addition of Al₂O₃ (Example 4) or ZnO (Example 3) decreases the percentage of so-called brittle specimens (0% of specimens with an elongation <12%), thus reducing the variability of the mechanical properties of sintered parts. This allows us to propose a powder that enables the production of printed parts with improved mechanical properties, while avoiding the production of parts with low elongation, i.e., <10%.

Claims

Demands

1. Polymer powder suitable for 3D printing by sintering, comprising (a) a semi-crystalline thermoplastic polymer, (b) one or more antioxidants and (c) a metal oxide, metal hydroxide, and / or hydrotalcite derived from one or more metals selected from aluminium, gallium, indium, magnesium, calcium, zinc and / or tin, preferably selected from zinc and / or aluminium.

2. Powder according to claim 1, wherein component (c) is selected from ZnO and Al2O3.

3. Powder according to any one of the preceding claims, wherein component (b) is selected from one or more phenolic antioxidants, one or more phosphite / phosphonite antioxidants, one or more thioethers and / or mixtures thereof.

4. Powder according to claim 3, wherein component (b) is selected from one or more phenolic antioxidants, one or more thioethers and / or mixtures thereof.

5. Powder according to any one of the preceding claims, wherein the semi-crystalline thermoplastic polymer is selected from: polyolefin, polyamide, polyester, polyarylether ketone, polyphenylene sulfide, polyacetal, polyimide, vinylidene fluoride polymer and / or mixture thereof, preferably a polyamide.

6. Powder according to claim 5, wherein the polyamide is selected from a homopolyamide, a copolyamide, a polyamide-polyether block copolymer (PEBA), and / or mixtures thereof.

7. Powder according to any one of the preceding claims, comprising fillers or reinforcements (d) and / or one or more additional additives (e).

8. Powder according to any one of the preceding claims, comprising: (a) 36 to 99.9%, preferably 40 to 95%, by weight of a thermoplastic polymer; (b) 0.1 to 2%, preferably 0.2 to 1%, by weight of one or more antioxidant(s); (c) 0.05 to 5%, preferably 0.1 to 1% by weight of a metal oxide, a metal hydroxide, and / or a hydrotalcite; (d) 0 to 50%, preferably 10 to 50%, and in particular 20 to 40% by weight of fillers or reinforcements; and (e) 0 to 10%, preferably 0.1 to 7.5%, in particular 1 to 5% by weight of additional additives, the respective proportions of components (a), (b), (c), (d) and (e) adding up to 100%.

9. Powder according to any one of the preceding claims, having a Dv50 diameter of 40 to 150 pm.

10. A method for preparing a powder according to any one of claims 1 to 9 comprising one or more of the following steps: (i) synthesis of a thermoplastic polymer (a), (ii) grinding of the thermoplastic polymer (a) into a powder of a Dv50 diameter of 40 to 150 pm, (iii) introduction of one or more antioxidant(s) (b), and of a metal oxide, a metal hydroxide, and / or a hydrotalcite (c), and optionally of one or more components (d) to (e), before or after step (ii).

11. A process for preparing a powder according to any one of claims 1 to 9 comprising the steps of: (i) prepolymerizing the monomer(s) of the thermoplastic polymer (a); (ii) grinding into a powder; (iii) subjecting the resulting prepolymer powder to solid-phase polycondensation to obtain a polymer powder; (iv) introducing one or more antioxidant(s) (b), a metal oxide, a metal hydroxide, and / or a hydrotalcite (c), optionally one or more components (d) to (e) into the prepolymer powder, by melt mixing or dry mixing, between steps (i) and (ii) and / or (ii) and (iii), and / or subsequently, by dry mixing.

12. Use of a metal oxide, a metal hydroxide, and / or a hydrotalcite derived from one or more metals selected from aluminium, gallium, indium, magnesium, calcium, zinc and / or tin, preferably selected from zinc and / or aluminium, in a polymer powder suitable for 3D printing by sintering, to improve the thermal stability, in particular to limit yellowing, of said powder.

13. Use of a metal oxide, metal hydroxide, and / or hydrotalcite derived from one or more metals selected from aluminium, gallium, indium, magnesium, calcium, zinc and / or tin, preferably selected from zinc and / or aluminium, in a polymer powder suitable for 3D printing by sintering, to improve the mechanical properties, in particular elongation at break, of printed parts manufactured from said powder.

14. Use according to any one of claims 12 or 13, wherein the powder comprises one or more antioxidants, preferably selected from one or more phenolic antioxidants, one or more phosphite / phosphonite antioxidants, one or more thioethers and / or mixtures thereof.

15. Use according to any one of claims 12 to 14, wherein the metal oxide is selected from ZnO and Al2O3.

16. A 3D printing process, preferably an electromagnetic radiation-induced sintering process, using a powder according to any one of claims 1 to 9, or a powder composition comprising a portion of said powder according to any one of claims 1 to 9 not agglomerated and recovered after one or more builds within the same printing process or a different printing process.

17. Manufactured article obtained by the 3D printing process of claim 16.

Images