Thermoplastic polymer compositions for constructing 3D objects

Abstract

The present invention relates to a composition for the layer-by-layer construction of three-dimensional articles by sintering of the composition induced by electromagnetic radiation, the composition comprising a semi-crystalline thermoplastic polymer powder and at least one wax having a dropping point higher than the crystallization temperature of the semi-crystalline thermoplastic polymer, and optionally further comprising a flow agent. The invention also relates to a method for preparing said composition and also to its use for the layer-by-layer construction of three-dimensional articles.

Description

[Technical Field]

[0001] This invention relates to a composition for the manufacture of layered three-dimensional (3D) articles by sintering, brought about by electromagnetic radiation. More specifically, this invention relates to a composition comprising a semicrystalline thermoplastic polymer powder and a wax, and a method for preparing the same. This invention also relates to the use of this composition and articles manufactured therefrom. [Background technology]

[0002] 3D object construction is often used in fields such as automobiles, ships, aviation, aerospace, medical (prosthetics, auditory systems, cell tissues, etc.), textiles, clothing, fashion, decoration, housings for electronic devices, telecommunications, home automation, computers, lighting, sports, and industrial tools to produce prototypes, model parts ("rapid prototyping"), or manufacture final parts in small series ("rapid production").

[0003] Among 3D object manufacturing technologies, the sintering method is particularly advantageous. In this method, a layer of polymer powder is selectively and briefly irradiated in a chamber with electromagnetic radiation (e.g., laser beam, infrared radiation, ultraviolet radiation), resulting in the melting of the radiation-affected powder particles. The molten particles fuse and solidify, forming a solid mass. This method allows for the simple production of 3D objects by repeatedly irradiating newly applied powder layers.

[0004] The quality and mechanical properties of manufactured parts depend on the properties of the polymer powder. Thermoplastic polymers are valued for use in applications where temperature and / or mechanical, and indeed even chemical, conditions are restricted. Thermoplastic elastomer polymers have proven particularly advantageous because, in a single polymer, they allow for the manufacture of lightweight and flexible parts by combining mechanical properties with very good resistance to thermal or UV aging and low density.

[0005] However, these thermoplastic polymer powders must be suitable for use in sintering equipment.

[0006] For example, the powder must be transported without agglomerating, forming lumps or cracks, and must be able to form a uniform layer.

[0007] By adding additives such as fluidizers, the flow properties can be improved to some extent.

[0008] To perform sintering, it is known that the powder layer should be maintained at a temperature within the working window between the crystallization temperature (Ct) and melting point (Mp) of the powder during manufacturing, in order to ensure good interlayer cohesion and avoid deformation. Therefore, in order to broaden the working window and make it easier to use in the sintering method, it is preferable to use a polymer with as large a difference between Mp and Ct as possible.

[0009] The term "working window" is understood to mean the temperature range of the powder layer over which sintering is actually possible.

[0010] However, for some powder compositions based on semicrystalline thermoplastic polymers, sintering was not always possible even when the difference in Mp-Ct between the polymers was sufficiently large. The working window may be narrow (e.g., below 5°C) or nonexistent.

[0011] Therefore, there is a need to provide a composition based on thermoplastic polymer powder, particularly thermoplastic elastomer polymers, that enables the manufacture of high-quality articles having good mechanical properties and accurate, clear dimensions and contours, while allowing for work within a wider working window, and that makes the method easier to implement.

[0012] Furthermore, problems with powder layer aggregation during sintering were observed. More specifically, the manufactured parts could sink into the powder layer and float to the edges, which hindered their completion.

[0013] Therefore, there is a need to provide a powder composition that enables reinforcement of the cohesiveness of the powder layer in order to prevent the parts from sinking into the powder layer during sintering.

[0014] There is also a need to provide such a thermoplastic polymer powder composition having good recyclability.

Summary of the Invention

[0015] The present invention makes it possible to meet the above needs.

[0016] According to a first aspect, the present invention relates to a composition for the layer-by-layer construction of three-dimensional (3D) articles by sintering a composition brought about by electromagnetic radiation, the composition comprising the following. - Semi-crystalline thermoplastic polymer powder, - A wax having a dropping point higher than the crystallization temperature (Ct) of the semi-crystalline thermoplastic polymer, - And an optional flow agent.

[0017] According to a particularly advantageous embodiment, the semi-crystalline thermoplastic polymer (scTP) is an elastomer.

[0018] The composition of the present invention makes it possible to construct 3D articles that exhibit good fineness and uniformity throughout the part with respect to its physical, mechanical, and actually chemical properties.

[0019] According to one embodiment of the present invention, the scTP polymer is selected from the following. - Polyamide, - Homopolymer or copolymer of vinylidene fluoride (PVDF), - A copolymer (PEBA) containing a polyamide block and a polyether block, - Thermoplastic polyurethane (TPU), - A copolymer (COPE) containing a polyester block and a polyether block, and - Their mixtures.

[0020] Preferably, the scTP polymer is an elastomer selected from the following. - PEBA, - TPU, - COPE, and - Their mixtures.

[0021] The wax can be selected particularly from polyolefin waxes, waxes of plant or animal origin, and their mixtures. For example, the wax can be selected from polyethylene wax and polypropylene wax, polytetrafluoroethylene wax, ketone wax, acid wax, partially esterified acid wax, acid anhydride wax, ester wax, aldehyde wax, amide wax, their derivatives, and their mixtures.

[0022] The present invention also relates to a method for preparing the above composition, - Supplying the SCTP polymer, preferably in powder form, and - Contacting the SCTP polymer with a wax and optionally a fluidizing agent including the method.

[0023] According to one embodiment, the operation of contacting the scTP polymer with the wax is performed by dry mixing.

[0024] According to one embodiment, the operation of contacting the scTP polymer with the wax is carried out as follows. - Dissolving the wax in a suitable solvent to form a wax solution, - Mixing the wax solution with the scTP polymer to form a dispersion, and - Removing the solvent from the dispersion, for example, by evaporation, to obtain the scTP polymer coated with the wax.

[0025] The present invention also relates to the use of the above composition for the construction of 3D articles layer by layer by sintering of the composition, preferably by electromagnetic radiation, preferably by laser radiation.

[0026] The present invention also relates to 3D articles manufactured from the above composition by layer-by-layer construction by sintering, preferably by electromagnetic radiation, and more preferably by laser radiation.

[0027] In relation to the present invention, the use of wax in the composition increases the width of the working window compared to the same composition without wax, thus enabling sintering production with a wide selection of scTP polymer-based compositions (whether they have a narrow working window or no working window at all).

[0028] This is particularly advantageous when the composition further contains a fluidizing agent.

[0029] Furthermore, it was observed that using wax enhances the cohesiveness of the powder layer during sintering, thereby preventing the manufactured parts from sinking into the powder layer and deforming. This constitutes another advantage of the present invention.

[0030] Therefore, according to another aspect, the present invention relates to the use of wax to increase the cohesiveness of an scTP polymer powder layer in a sintering process by electromagnetic radiation, preferably laser radiation.

[0031] The composition according to the present invention exhibits even better recyclability.

[0032] While I don't intend to rely on any specific theory, it seems that the wax adheres to the polymer particles at a certain temperature in the powder layer, thereby increasing the cohesiveness of the powder layer. In other words, once sintering occurs and the temperature of the powder layer decreases, the wax hardens and separates from the unsintered polymer particles, making them recyclable and reusable.

[0033] According to one aspect, the present invention relates to the use of a specific wax in an scTP polymer-based powder composition to improve the recyclability of the powder during the construction of 3D articles by sintering.

[0034] In another aspect, the present invention relates to a method for manufacturing an article by sintering using the above composition, the method comprising the step of recycling unsintered powder.

[0035] According to one embodiment, the composition is reused in several successive constructions.

[0036] In yet another aspect, the present invention relates to a 3D article obtained from a composition comprising recycled scTP polymer powder. [Modes for carrying out the invention]

[0037] <Semi-crystalline thermoplastic polymer> The thermoplastic polymer according to the present invention is semi-crystalline. The term "semi-crystalline thermoplastic polymer" is understood to mean a thermoplastic polymer that exhibits the following characteristics: - During the cooling stage in DSC (Differential Scanning Calorimetry) at a rate of 20 K / min, the crystallization temperature (Ct) was determined according to the standard ISO 11357-3:2013. - During the heating stage in DSC at a rate of 20K / min, the melting point (Mp) determined according to standard ISO 11357-3:2013, and - In the DSC heating stage at a rate of 20 K / min, the enthalpy of fusion (ΔHf) is greater than 5 J / g, preferably greater than 10 J / g, for example greater than 20 J / g, generally less than 200 J / g, preferably less than 150 J / g, for example less than 100 J / g or less than 50 J / g, as determined according to standard ISO 11357-3:2013.

[0038] The semicrystalline thermoplastic polymer of the present invention may have an Mp of 100 to 300°C, preferably 120 to 200°C. This Mp corresponds to the initial heating. The scTP polymer may have a Ct of 40 to 250°C, preferably 45 to 200°C, for example, 45 to 150°C.

[0039] Typically, Mp and Ct are measured directly from scTP powder.

[0040] In the case of a polymer mixture, the lowest Mp in the polymer mixture is considered to be Mp, and the highest Ct in the polymer mixture is considered to be Ct.

[0041] The difference between Ct and Mp in the scTP polymer is preferably 20°C or higher, preferably 30°C or higher, more preferably 40°C or higher, or 50°C or higher, or 60°C or higher, or 70°C or higher, or 80°C or higher.

[0042] The scTP polymer of the present invention can be selected from polyamides, PVDF, PEBA, TPU, COPE, and mixtures thereof.

[0043] <Polyamide> According to one embodiment, the semi-crystalline thermoplastic polymer is a semi-crystalline polyamide (scPA). It may be a homopolyamide or copolyamide, or a mixture thereof.

[0044] Therefore, the polyamide according to the present invention can be obtained by polymerization of one monomer (homopolyamide) or at least two different monomers (copolyamide) selected from the following. - Amino acids or aminocarboxylic acid type monomers, preferably α,ω-aminocarboxylic acids, - Lactam-type monomers having 3 to 18 carbon atoms in the main ring and which can be substituted. - A "diamine-diacid" type monomer resulting from a reaction between an aliphatic diamine having 4 to 36 carbon atoms, preferably 4 to 18 carbon atoms, and a dicarboxylic acid having 4 to 36 carbon atoms, preferably 4 to 18 carbon atoms, and - In the case of a mixture between amino acid type monomers and lactam type monomers, the monomers have different numbers of carbon atoms, and the mixture is of those monomers.

[0045] In this explanation, the term "monomer" should be understood as meaning "repeating unit." This is because the case where the repeating unit of polyamide (PA) consists of a combination of diamine and diacid is special. In this case, the monomer is considered to correspond to the combination of diamine and diacid, that is, a diamine-diacid pair (equomolar amount). This is explained by the fact that individually, diacid or diamine is merely a structural unit and is insufficient on its own for polymerization.

[0046] Regarding amino acid-type monomers, examples of α,ω-amino acids include those having 4 to 18 carbon atoms, such as aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, N-heptyl-11-aminoundecanoic acid, and 12-aminododecanoic acid.

[0047] Examples of lactam-type monomers include those having 3 to 18 carbon atoms on the main ring and being substituted. For example, β,β-dimethylpropiolactam, α,α-dimethylpropiolactam, amyloractam, caprolactam (also known as lactam 6), caprilactam (also known as lactam 8), oenantractam, and laurylactam (also known as lactam 12).

[0048] Regarding "diamine-diacid" type monomers, examples of dicarboxylic acids include acids having 4 to 36 carbon atoms. For example, adipic acid, sebacic acid, azelaic acid, suberic acid, isophthalic acid, butanediic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, sodium or lithium salts of sulfisoisophthalic acid, dimerized fatty acids (these dimerized fatty acids have a dimer content of at least 98% and are preferably hydrogenated), and dodecanediic acid HOOC-(CH2) 10 Examples include -COOH and tetradecanediic acid.

[0049] The terms "fatty acid dimer" or "dimerized fatty acid" are understood, more specifically, to mean the product of a dimerization reaction of fatty acids (generally containing 18 carbon atoms, often a mixture of oleic acid and / or linoleic acid). It contains 0% to 15% carbon. 18 Monoacid, 60% to 99% carbon 36 Dioxide, and 0.2% to 35% C 54 It is preferable that the mixture contains or contains three or more triacids or polyacids.

[0050] Examples of diamines include aliphatic diamines having 4 to 36 atoms, preferably 4 to 18 atoms, which may be arylic and / or saturated cyclic. Examples include hexamethylenediamine, piperazine (abbreviated as "Pip"), aminoethylenepiperazine, tetramethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, 1,5-diaminohexane, 2,2,4-trimethyl-1,6-diaminohexane, polyoldiamine, isophoronediamine (IPD), methylpentamethylenediamine (MPMD), bis(aminocyclohexyl)methane (BACM), bis(3-methyl-4-aminocyclohexyl)methane (BMACM), bis(p-aminocyclohexyl)methane (generally represented as "PACM"), meta-xylylenediamine, and bis(p-aminocyclohexyl)methane.

[0051] More specifically, examples of diamine diacids include those resulting from the condensation of 1,6-hexamethylenediamine with a dicarboxylic acid having 6 to 36 carbon atoms, and those resulting from the condensation of 1,10-decamethylenediamine with a diacid having 6 to 36 carbon atoms.

[0052] In particular, examples of "diamine-diacid" type monomers include monomers 66, 610, 611, 612, 614, and 618. Decanediamine and C6~C 36 Monomers resulting from the condensation of diacids, particularly monomers 1010, 1012, 1014, and 1018, can be cited. In the numerical notation XY, X represents the number of carbon atoms resulting from the diamine residue, and Y represents the number of carbon atoms resulting from the diacid residue, as in the conventional method.

[0053] Homopolyamides are typically aliphatic homopolyamides, and preferably linear aliphatic homopolyamides.

[0054] Copolyamides can be aliphatic, aromatic, or semi-aromatic.

[0055] According to one embodiment, scPA is a semi-aromatic copolyamide of formula X / YAr, in particular A / XT, where A is selected from units obtained from amino acids, units obtained from lactams, and units corresponding to the (diamine-diacid) formula, as described in EP1505099.

[0056] Examples of (co)polyamides include PA410, PA4T, PA66, PA46, PA610, PA612, PA11, PA12, PA910, PA912, PA913, PA914, PA915, PA916, PA918, PA936, PA1010, PA1012, PA1013, PA1014, PA1210, PA1212, PA1213, PA1214, PA614, PA613, PA615, PA616, PA618, PA MXD6, PA MXD10, PA12T, PA10T, PA9T, PA18T, PA6T / 66, PA66 / 6T / 6I, and PA6 / 6T. XT is Cx A unit obtained from the polycondensation of a diamine and terephthalic acid, where x is C x The diamine has a number of carbon atoms, x is between 6 and 36, preferably between 9 and 18, and is a polyamide of A / 6T, A / 9T, A / 10T or A / 11T in particular, A is as defined above, and is a polyamide selected from MPMDT / 6T, 5T / 10T, 11 / BACT, 11 / 6T / 10T, MXDT / 10T, MPMDT / 10T, BACT / 10T, BACT / 6T, BACT / 10T / 6T, 11 / BACT / 6T, 11 / MPMDT / 6T, 11 / MPMDT / 10T, 11 / BACT / 10T, 11 / MXDT / 10T and 11 / 5T / 10T, T corresponds to terephthalic acid, MXD corresponds to m-xylylenediamine, MPMD corresponds to methylpentamethylenediamine, and BAC corresponds to bis(aminomethyl)cyclohexane.

[0057] According to a preferred embodiment, the polyamide is selected from polyamide (PA) 11, PA12, or PA6.

[0058] In relation to the present invention, the homopolyamide or copolyamide is an scTP polymer having the above-mentioned Ct, Mp, and ΔHf.

[0059] <Vinylidene fluoride polymer (PVDF)> According to one embodiment, the semi-crystalline thermoplastic polymer is PVDF.

[0060] PVDF can be a homopolymer or copolymer.

[0061] In this specification, "copolymer" refers collectively to a polymer obtained by polymerization of VDF with at least one other comonomer, i.e., a polymer having repeating units derived from VDF and repeating units derived from at least one other comonomer. Preferably, it is a copolymer in the strict sense, i.e., a copolymer having repeating units derived from VDF and repeating units derived from just one other comonomer.

[0062] Preferably, the comonomer(s) is / are halogenated alkenes, more preferably fluoroalkenes. Particularly, halogenated propenes or halogenated ethylenes, more specifically fluoroethylene (or vinyl fluoride), chlorofluoroethylene (1-chloro-1-fluoroethylene and 1-chloro-2-fluoroethylene), trifluoroethylene, chlorodifluoroethylene (particularly 1-chloro-2,2-difluoroethylene), 1-bromo-2,2-difluoroethylene, bromotrifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, trifluoropropene (particularly 3,3,3-trifluoropropene), tetrafluoropropene (particularly 2,3,3,3-tetrafluoropropene), chlorotrifluoropropene (particularly 2-chloro-3,3,3-trifluoropropene), pentafluoropropene (particularly 1,1,3,3,3-pentafluoropropene or 1, ,3,3,3-pentafluoropropene) and hexafluoropropene also called hexafluoropropylene. It may also be a perfluoroalkyl vinyl ether of the general formula R f -O-CF-CF2, where R f is an alkyl group, preferably a C1-C4 alkyl group. Preferred examples are PPVE (perfluoropropyl vinyl ether) and PMVE (perfluoromethyl vinyl ether).

[0063] PVDF can be obtained by known polymerization methods such as solution polymerization, emulsion polymerization or suspension polymerization. According to one embodiment, it is prepared by an emulsion polymerization method in the absence of a fluorinated surfactant.

[0064] When PVDF is a copolymer, it may be homogeneous or heterogeneous, preferably it can be homogeneous. A homogeneous copolymer shows a uniform chain structure and the statistical distribution of the comonomer does not change between polymer chains. In a heterogeneous copolymer, the polymer chains show a multimodal or broadened distribution as the average content of the comonomer, and thus contain polymer chains rich in one kind of comonomer and polymer chains poor in the comonomer. Examples of heterogeneous PVDF are described in document WO2007 / 080338.

[0065] A homogeneous copolymer can be prepared in a one-step method by gradually injecting comonomers while maintaining a constant mass ratio between them.

[0066] According to a preferred embodiment, the polymer is an scTP elastomer polymer selected from PEBA copolymer, TPU, or COPE.

[0067] Preferably, the thermoplastic elastomer exhibits an instantaneous hardness of 40 Shore D or less, more preferably 35 Shore D or less. Hardness measurement can be performed according to the standard ISO 868:2003.

[0068] <Copolymer (PEBA) containing polyamide blocks and polyether blocks> According to one embodiment, the semicrystalline thermoplastic polymer is a "PEBA" copolymer, which may preferably be a linear (non-crosslinked) copolymer. PEBA is obtained from the polycondensation of a polyamide block containing reactive end groups and a polyether block containing reactive end groups, particularly the following polycondensation. 1) Polyamide blocks containing diamine chain ends and polyoxyalkylene blocks containing dicarboxyl chain ends 2) Polyamide blocks containing dicarboxyl chain ends and polyoxyalkylene blocks containing diamine chain ends are obtained, for example, by cyanoethylation and hydrogenation of aliphatic α,ω-dihydroxylated polyoxyalkylene blocks known as polyetherdiols. 3) A polyamide block containing a dicarboxyl chain terminus and a polyetherdiol, the product of which in this particular case is a polyetheresteramide.

[0069] Polyamide blocks containing dicarboxyl chain ends are derived, for example, from the condensation of polyamide precursors in the presence of chain-restricting dicarboxylic acids. Polyamide blocks containing diamine chain ends are derived, for example, from the condensation of polyamide precursors in the presence of chain-restricting diamines.

[0070] Three types of polyamide blocks can be used advantageously.

[0071] According to the first type, the polyamide block is derived from the condensation of a dicarboxylic acid, particularly one having 4 to 20 carbon atoms, preferably one having 6 to 18 carbon atoms, and an aliphatic or aromatic diamine, particularly one having 2 to 20 carbon atoms, preferably one having 6 to 14 carbon atoms.

[0072] Examples of dicarboxylic acids include butanediic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, terephthalic acid, and isophthalic acid, as well as dimerized fatty acids.

[0073] Examples of diamines include tetramethylenediamine, hexamethylenediamine, 1,10-decamethylenediamine, dodecamethylenediamine, and trimethylhexamethylenediamine.

[0074] Advantageously, polyamide blocks PA412, PA414, PA418, PA610, PA612, PA614, PA618, PA912, PA1010, PA1012, PA1014, and PA1018 can be used.

[0075] In PA XY notation, X represents the number of carbon atoms derived from the diamine residue, and Y represents the number of carbon atoms derived from the diacid residue, as in the conventional method.

[0076] According to the second type, polyamide blocks are produced from the condensation of one or more α,ω-aminocarboxylic acids and / or one or more lactams having 6 to 12 carbon atoms. Examples of lactams include caprolactam, oenantractam, and laurylactam. Examples of α,ω-aminocarboxylic acids include aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

[0077] Advantageously, the second type of polyamide block is a PA11 (polyundecaneamide) block, a PA12 (polydodecaneamide) block, or a PA6 (polycaprolactam) block.

[0078] In PA X notation, X represents the number of carbon atoms derived from an amino acid residue.

[0079] This type of condensation can be carried out in the presence of a chain limiting agent, such as a dicarboxylic acid or diamine having 4 to 12 carbon atoms.

[0080] According to the third type, the polyamide block is obtained from the condensation of at least one α,ω-aminocarboxylic acid (or one lactam), at least one diamine, and at least one dicarboxylic acid.

[0081] In this case, the polyamide PA block is prepared by the following polycondensation. - A linear aliphatic or aromatic diamine containing X carbon atoms, - A dicarboxylic acid containing Y carbon atoms, and - A comonomer (or multiple comonomer) (Z) selected from an equimolar mixture of a lactam and an α,ω-aminocarboxylic acid containing Z carbon atoms, and at least one diamine containing X1 carbon atoms and at least one dicarboxylic acid containing Y1 carbon atoms, wherein (X1, Y1) is different from (X, Y), - The comonomer(s) {Z} is introduced in a weight ratio of up to 50%, preferably up to 20%, and more preferably up to 10%, relative to the total amount of the polyamide precursor monomer. - The polycondensation is carried out in the presence of a chain limiting agent selected from dicarboxylic acids.

[0082] It is advantageous to use a dicarboxylic acid containing Y carbon atoms as a chain limiting agent, which is introduced in excess of the diamine(s) stoichiometry.

[0083] According to one variation of this third type, the polyamide block is obtained from the condensation of at least two α,ω-aminocarboxylic acids, or at least two lactams containing 6 to 12 carbon atoms, or one lactam and one aminocarboxylic acid that do not have the same number of carbon atoms, in the presence of any chain limiting agent.

[0084] Examples of aliphatic α,ω-aminocarboxylic acids include aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

[0085] Examples of lactams include caprolactam, oenantractam, and laurilactam.

[0086] Examples of aliphatic diamines include hexamethylenediamine, dodecamethylenediamine, and trimethylhexamethylenediamine.

[0087] Examples of aliphatic diacids include butanediic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid, and dimerized fatty acids. These dimerized fatty acids preferably have a dimer content of at least 98%, and preferably they are hydrogenated. These include, for example, products marketed by Croda under the trademark Pripol(R), or by BASF under the trademark Empol(R), or by Oleon under the trademark Radiacid(R), and polyoxyalkylene-α,ω-diacids.

[0088] Examples of aromatic diacids include terephthalic acid (T) and isophthalic acid (I).

[0089] Examples of a third type of polyamide block include the following: - PA66 / 6, where 66 represents the hexamethylenediamine unit condensed with adipic acid, and 6 represents the unit resulting from the condensation of caprolactam. - PA66 / 610 / 11 / 12, where 66 represents hexamethylenediamine condensed with adipic acid, 610 represents hexamethylenediamine condensed with sebaciic acid, 11 represents a unit resulting from the condensation of aminoundecanoic acid, and 12 represents a unit resulting from the condensation of laurylactam.

[0090] The notations PA X / Y, PA X / Y / Z, etc., refer to copolyamides where X, Y, and Z represent homopolyamide units as described above.

[0091] Advantageously, the polyamide blocks of copolymers used in the present invention are polyamides PA6, PA11, PA12, PA54, PA59, PA510, PA512, PA513, PA514, PA516, PA518, PA536, PA64, PA69, PA610, PA612, PA613, PA614, PA616, PA618, PA636, PA104, PA109, PA1010, PA1012, PA1013 The material comprises PA1014, PA1016, PA1018, PA1036, PA10T, PA124, PA129, PA1210, PA1212, PA1213, PA1214, PA1216, PA1218, PA1236, PA12T, or mixtures or copolymers thereof, preferably polyamide PA6, PA11, PA12, PA610, PA1010, PA1012, or mixtures or copolymers thereof.

[0092] Polyether blocks consist of alkylene oxide units.

[0093] Polyether blocks may be, in particular, blocks derived from PEG (polyethylene glycol), i.e., blocks consisting of ethylene oxide units, and / or blocks derived from PPG (propylene glycol), i.e., blocks consisting of propylene oxide units, and / or blocks derived from PO3G (polytrimethylene glycol), i.e., blocks consisting of polytrimethylene glycol ether units, and / or blocks derived from PTMG, i.e., blocks consisting of tetramethylene glycol units, also called polytetrahydrofuran. PEBA copolymers can contain several types of polyethers in their chains, and the copolymers can be block or random.

[0094] Alternatively, blocks obtained by oxyethylation of bisphenol (e.g., bisphenol A) may be used. These latter products are described in particular in reference EP613919.

[0095] Polyether blocks can also consist of ethoxylated primary amines. Examples of ethoxylated primary amines include the products of the following formulas. [ka] In the formula, m and n are integers between 1 and 20, and x is an integer between 8 and 18. These products are commercially available, for example, under the trademark Noramox(R) from CECA and under the trademark Genamin(R) from Clariant.

[0096] Polyether blocks may include polyoxyalkylene blocks containing NH2 chain termini, such blocks can be obtained by cyanoacetylation of aliphatic α,ω-dihydroxylated polyoxyalkylene blocks known as polyetherdiols. More specifically, commercially available Jeffamine or Elastamine products can be used (e.g., Jeffamine(R) D400, D2000, ED2003, or XTJ542, which are commercially available from Huntsman and are also described in references JP2004346274, JP2004352794, and EP1482011).

[0097] The polyetherdiol block is either used as is and co-condensed with a polyamide block containing a carboxyl-terminated group, or it is converted to a polyetherdiamine and aminated for condensation with a polyamide block containing a carboxyl-terminated group.

[0098] A general method for the two-step preparation of PEBA copolymers having an ester bond between a PA block and a PE block is known, for example, described in reference FR2846332. A general method for the preparation of PEBA copolymers having an amide bond between a PA block and a PE block is also known, for example, described in reference EP1482011. Furthermore, to prepare polymers containing a polyamide block and a polyether block having randomly distributed units, the polyether block can be mixed with a polyamide precursor and a diacid chain limiter (one-step method).

[0099] Of course, the term PEBA in this description of the present invention also refers precisely to PEBAX(R) products sold by Arkema, Vestamid(R) products sold by Evonik(R), Grilamid(R) products sold by EMS, PEBA-type Pelestat(R) products sold by Sanyo, or any other PEBA from other suppliers.

[0100] The block copolymers described above generally include at least one polyamide block and at least one polyether block, but the present invention also includes all copolymers that include two, three, four (in fact, more) different blocks selected from those described herein, provided that these blocks include at least one polyamide block and one polyether block.

[0101] For example, the copolymer according to the present invention may include a segmented block copolymer (or "triblock" copolymer) comprising three different types of blocks resulting from the condensation of several of the blocks. The triblock is preferably selected from copolyether ester amides and copolyether amide urethanes.

[0102] Particularly preferred PEBA copolymers in connection with the present invention are copolymers comprising the following types of blocks: namely, PA11 derived from PEG, PA11 derived from PTMG, PA12 derived from PEG, PA12 derived from PTMG, PA1010 derived from PEG, PA1010 derived from PTMG, PA610 derived from PTMG, PA610 derived from PEG, PA6 derived from PEG, and PA6 derived from PTMG.

[0103] The number-average molar mass of polyamide blocks in the PEBA copolymer is preferably in the range of 100 to 20,000 g / mol, more preferably 200 to 10,000 g / mol, and even more preferably 200 to 2,000 g / mol. Therefore, the number-average molar mass of polyamide blocks in the PEBA copolymer is 100-200 g / mol, or 200-500 g / mol, or 500-1000 g / mol, or 1000-1500 g / mol, or 1500-2000 g / mol, or 2000-2500 g / mol, or 2500-3000 g / mol, or 3000-3500 g / mol, or 3500-4000 g / mol, or 4000-5000 g / mol, or 5000-6000 g / mol, or 6000-7000 g / mol, or 7000 It has a value of ~8000 g / mol, or 8000~9000 g / mol, or 9000~10000 g / mol, or 10000~11000 g / mol, or 11000~12000 g / mol, or 12000~13000 g / mol, or 13000~14000 g / mol, or 14000~15000 g / mol, or 15000~16000 g / mol, or 16000~17000 g / mol, or 17000~18000 g / mol, or 18000~19000 g / mol, or 19000~20000 g / mol.

[0104] The number-average molar mass of the polyether block is preferably 100 to 6000 g / mol, more preferably 200 to 3000 g / mol, and even more preferably 800 to 2500 g / mol. In this embodiment, the number-average molar mass of the polyether block has a value of 100-200 g / mol, or 200-500 g / mol, or 500-800 g / mol, or 800-1000 g / mol, or 1000-1500 g / mol, or 1500-2000 g / mol, or 2000-2500 g / mol, or 2500-3000 g / mol, or 3000-3500 g / mol, or 3500-4000 g / mol, or 4000-4500 g / mol, or 4500-5000 g / mol, or 5000-5500 g / mol, or 5500-6000 g / mol.

[0105] The number-average molar mass is determined by the amount of chain limiting agent. The number-average molar mass can be calculated according to the following relationship:

number

[0106] In this formula,

number

number

number

number

[0107] The number-average molar mass of polyamide and polyether blocks can be measured by gel permeation chromatography (GPC) before copolymerization of the blocks.

[0108] The weight ratio of polyamide blocks to polyether blocks in a PEBA copolymer can be particularly between 0.1 and 20. This weight ratio can be calculated by dividing the number-average molar mass of polyamide blocks by the number-average molar mass of polyether blocks. Therefore, the weight ratio of polyamide blocks to polyether blocks in a PEBA copolymer can be 0.1-0.2, or 0.2-0.3, or 0.3-0.4, or 0.4-0.5, or 0.5-1, or 1-2, or 2-3, or 3-4, or 4-5, or 5-7, or 7-10, or 10-13, or 13-16, or 16-19, or 19-20.

[0109] A range of 2 to 19, and more specifically, a range of 4 to 10, is particularly preferred.

[0110] <Copolymer containing polyester blocks and polyether blocks (COPE)> According to one embodiment, the scTP polymer is a COPE, also known as a copolyether ester.

[0111] Therefore, the COPE according to the present invention comprises any thermoplastic elastomer polymer including at least one polyether (PE) block and at least one polyester PES block (homopolymer or copolyester).

[0112] COPE comprises flexible PE blocks derived from polyetherdiols and rigid polyester blocks derived from the reaction of at least one dicarboxylic acid with at least one chain-extending short diol unit. The PES block and PE block are linked via ester bonds resulting from the reaction of the acidic functional group of the dicarboxylic acid with the OH functional group of the polyetherdiol. The chain-extending short diol is neopentyl glycol and a compound of the formula HO(CH2) where n is an integer with a value of 2 to 10. nThe group consisting of OH aliphatic glycols can be selected. The bond between the polyether and the diacid forms a flexible block, while the bond between the glycol or butanediol and the diacid forms a rigid block of copolyether ester. Advantageously, the diacid is an aromatic dicarboxylic acid having 8 to 14 carbon atoms. Up to 50 mol% of the aromatic dicarboxylic acid can be replaced with at least one other aromatic dicarboxylic acid having 8 to 14 carbon atoms, and / or up to 20 mol% can be replaced with an aliphatic dicarboxylic acid having 2 to 14 carbon atoms. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, dibenzoic acid, naphthalenedicarboxylic acid, 4,4'-diphenylenedicarboxylic acid, bis(p-carboxyphenyl)methaneic acid, ethylenebis(p-benzoic acid), 1,4-tetramethylenebis(p-oxybenzoic acid), ethylenebis(p-oxybenzoic acid), or 1,3-trimethylenebis(p-oxybenzoic acid). Examples of glycols include ethylene glycol, 1,3-trimethylene glycol, 1,4-tetramethylene glycol, 1,6-hexamethylene glycol, 1,3-propylene glycol, 1,8-octamethylene glycol, or 1,10-decamethylene glycol.

[0113] COPE is a copolymer having PE units derived from polyetherdiols such as polyethylene glycol (PEG), polypropylene glycol (PPG), polytrimethylene glycol (PO3G), or polytetramethylene glycol (PTMG), and PES units resulting from the reaction of dicarboxylic acids such as terephthalic acid with glycols, ethanediols, or 1,4-butanediols. Such copolyether esters are described in Japanese Patents EP402883 and EP405227.

[0114] Thermoplastic polyurethane (TPU) According to one embodiment, the semi-crystalline thermoplastic polymer is a copolymer comprising a polyurethane (PU) block and a polyether (PE) block, also known as TPU, or polyether urethane.

[0115] TPU is produced from the condensation of a flexible PE block and a rigid PU block, both of which are polyetherdiols. The PU block and the PE block are bonded together via bonds resulting from the reaction between the isocyanate functional groups of the polyurethane and the -OH functional groups of the polyetherdiol.

[0116] In the sense of the present invention, the term "PU" is understood to mean the product resulting from the reaction of at least one diisocyanate, which can be selected from aromatic diisocyanates (e.g., MDI, TDI) and / or aliphatic diisocyanates (e.g., HDI or hexamethylene diisocyanate), with at least one short diol. The short diol extending this chain can be selected from the glycols described above in the description of copolyether esters. The PU involved in the composition of the copolymer according to the present invention may include all types of polyols, particularly those of renewable origin, such as polyols derived from starch (erythritol, sorbitol, maltitol, mannitol), polyols derived from sugars such as sucrose (isomalto, xylitol), or polyols derived from corn, soybeans, cotton, rapeseed, sunflower, or peanuts (glycerol, propylene glycol, ethylene glycol, reaction by-products of biodiesel production). Other examples of polyols that may be involved in the composition of these polyurethanes include polyethylene glycol (PEG), poly(1,2-propylene glycol) (PPG), poly(1,3-propylene glycol) (PO3G), or polytetramethylene glycol (PTMG).

[0117] According to one embodiment, the semi-crystalline thermoplastic elastomer polymer can also be selected from copolymers comprising styrene blocks (TPS), thermoplastic polyolefin elastomers (TPO), or thermoplastic vulcanized products (TPV). Examples of commercially available materials derived from commercially available thermoplastic elastomer polymers include, for example, Cawiton(R), Thermolast K(R), Thermolast M(R), Sofprene(R), Dryflex(R), and Laprene(R)(TPS), Desmopan(R) or Elastollan(R)(TPU), Santoprene(R), Termoton(R), Solprene(R), Thermolast V(R), Vegaprene(R), or Forprene(R)(TPV), and For-Tec E(R) or Engage, Ninjaflex(R)(TPO).

[0118] According to one embodiment, the semi-crystalline thermoplastic polymer is a polymer selected from polyoxymethylene (POM) homopolymers and copolymers, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphthalamide (PPA), and poly(p-phenylene terephthalamide).

[0119] <wax> The wax of the present invention is generally a compound that is solid at ambient temperature. The wax is malleable at 20°C.

[0120] The wax can exhibit a coarse to fine crystalline structure and a translucent to opaque appearance, but without being glassy. The wax can begin to melt above 40°C without decomposing. The wax can exhibit a melt viscosity (less than 10,000 mPa·s) 10°C above its dropping point.

[0121] Waxes can be hydrophobic compounds.

[0122] The wax used in the present invention can be selected from synthetic waxes such as polyolefin waxes, waxes of mineral origin (e.g., montan wax), petroleum origin, plant origin (e.g., carnauba wax or candelilla wax), or animal origin, as well as mixtures thereof.

[0123] The waxes described above generally consist of hydrocarbon compounds containing 10 to 100 carbon atoms, preferably 15 to 60 carbon atoms. According to a particularly advantageous embodiment, the wax is a functionalized wax of the above type that can contain at least one polar group selected from esters, ethers, acids, acid anhydrides, carboxylate salts, amides, amines, or alcohols, preferably esters, acids, acid anhydrides, or amides. The acid group is typically a carboxylic acid.

[0124] Functionalized waxes can be obtained by functionalizing existing waxes, particularly through oxidation or grafting reactions. Alternatively, functionalized waxes can be obtained by introducing monomers having functional groups during polymerization reactions.

[0125] While we do not intend to rely on any specific theory, these polar groups appear to readily interact with scTP polymers, creating weak bonds on the surface of the scTP polymer powder, such as hydrogen or van der Waals type weak bonds. This improves the cohesiveness of the powder and, in particular, increases the hardness of the powder layer at the construction temperature.

[0126] Preferably, the wax used in connection with the present invention has an acid value in the range of 2 to 100, preferably 3 to 90 mg KOH / g, for example, 2 to 10, or 10 to 20, or 20 to 50, or 50 to 90 mg KOH / g. When polyamide or PEBA-type scTP polymers are used in connection with the present invention, it has been observed that the higher the acid value of the wax, the greater the cohesiveness of the powder layer compared to waxes having similar dropping points.

[0127] In relation to the present invention, the acid value was measured using a 50:50 v / v xylene / ethanol mixture as the titration solvent, in accordance with the standard DIN EN ISO 2114-November 2000.

[0128] 1 g of the wax sample was weighed into a 250 ml Erlenmeyer flask and dissolved in 100 ml of hot xylene / ethanol mixture (approximately 90°C) on a magnetic stirrer. Subsequently, the sample was placed on the magnetic stirrer 20 of the titrator, the electrode was fully immersed, and the mixture was titrated with a 0.1 M ethanolic KOH solution.

[0129] According to one embodiment, the wax can be selected from polyethylene wax and polypropylene wax, polytetrafluoroethylene wax, ketone wax, acid wax, partially esterified acid wax, acid anhydride wax, ester wax, aldehyde wax, amide wax, derivatives thereof and mixtures thereof, preferably polyethylene wax and polypropylene wax, acid wax, partially esterified acid wax, acid anhydride wax, ester wax, amide wax, derivatives thereof and / or mixtures thereof.

[0130] Waxes can typically be mixed in a dry or molten state.

[0131] Polyolefin waxes may be ethylene homopolymers and / or propylene homopolymers and / or 1-butene homopolymers. Polyolefin waxes may be copolymers of at least two olefins (e.g., polymers of a mixture of ethylene, propylene, and / or 1-butene). They may also be copolymers of ethylene and propylene. According to one embodiment, polyolefins may be linear or branched polyolefins having 20 to 200 carbon atoms, preferably 40 to 100 carbon atoms. They may also be substituted with aliphatic groups and / or aromatic groups. Examples of such polyolefins include 1-hexene, 1-octene or 1-octadecene, and styrene. For example, a polyolefin wax used in connection with the present invention is "Crayvallac WN1495(R)" wax sold by Arkema.

[0132] The polytetrafluoroethylene waxes that can be used in connection with this invention are "Ceridust 9202F(R)" sold by Clariant or "Crayvallac WF-1000(R)" sold by Arkema.

[0133] The acid wax that can be used in connection with this invention is "Licowax S(R)", a wax sold by Clariant.

[0134] The ester waxes that can be used in connection with the present invention are polyhydroxyalkanoate waxes, such as "Ceraflour 1000(R)" sold by Byk and "Licowax OP(R)" sold by Clariant.

[0135] According to one embodiment, the wax may be a wax derived from crude oil, such as paraffin. Paraffin wax contains essentially straight-chain hydrocarbons and may also contain branched hydrocarbons such as isoparaffins and other branched substances, as well as cycloalkanes such as cycloparaffins and other cyclic substances.

[0136] According to one embodiment, polyolefin waxes can be functionalized with acid anhydrides such as maleic anhydride. For example, such a wax is "Ceridust 8020(R)" sold by Clariant.

[0137] Amide waxes can be prepared by the reaction of long-chain carboxylic acids (typically fatty acids) with amines, diamines, or ammonia.

[0138] According to a specific embodiment, the amide wax is C2-C 24 Aliphatic diamines, C6~C 18 Alicyclic diamines, C6~C 24 The present invention includes diamides obtained from diamines selected from aromatic diamines or mixtures thereof.

[0139] Aliphatic diamines are linear or branched, preferably linear. Suitable linear aliphatic diamines include 1,2-ethylenediamine, 1,3-propylenediamine, 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,8-octamethylenediamine, 1,12-dodecamethylenediamine, and mixtures thereof, preferably 1,2-ethylenediamine, 1,5-pentamethylenediamine, and 1,6-hexamethylenediamine. Suitable branched aliphatic diamines include 1,2-propylenediamine, 2,2-dimethyl-1,3-propanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, and mixtures thereof.

[0140] Alicyclic diamines are non-aromatic diamines that contain a ring, particularly a ring having six carbon atoms. C6~C 18Alicyclic diamines are alicyclic diamines containing 6 to 18 carbon atoms. Suitable examples of alicyclic diamines are 1,2-, 1,3- or 1,4-diaminocyclohexane, 2-methylcyclohexane-1,3-diamine, 4-methylcyclohexane-1,3-diamine, isophorone diamine, 1,2-, 1,3- or 1,4-bis(aminomethyl)cyclohexane, diaminodecahydronaphthalene, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexylmethane, bis(aminomethyl)norbornane, and mixtures thereof, preferably 1,3- or 1,4-bis(aminomethyl)cyclohexane, 1,2-, 1,3- or 1,4-bis(aminomethyl)cyclohexane, isophorone diamine, and 4,4'-diaminodicyclohexylmethane.

[0141] Aromatic diamines are diamines that contain an aromatic ring. C6~C 24 Aromatic diamines are aromatic diamines containing 6 to 24 carbon atoms. Suitable examples of aromatic diamines are meta- and para-phenylenediamines, meta- and para-xylylenediamines, meta- and para-toluylenediamines, 3,4'-diaminodiphenyl ethers, 4,4'-diaminodiphenyl ethers, 4,4'-diaminodiphenylmethane, and mixtures thereof, preferably meta- and para-xylylenediamines.

[0142] Preferably, the amide wax is C2-C 24 Aliphatic diamines, especially linear C2-C2 diamines. 18 Aliphatic diamines, more specifically linear C2-C 12 The diamides include aliphatic diamines, and more specifically, diamides obtained from at least one diamine selected from 1,2-ethylenediamine, 1,5-pentamethylenediamine, or 1,6-hexamethylenediamine. According to certain embodiments, the amide wax is at least one C2-C 36 This includes diamides obtained from carboxylic acids. Diamides are C2-C 36 It can be obtained as a mixture of carboxylic acids.

[0143] Carboxylic acids can be linear or branched, preferably linear. Carboxylic acids can be saturated or unsaturated, preferably saturated. Carboxylic acids can be unsubstituted or substituted, and can be hydroxylated in particular. Hydroxylated carboxylic acids are carboxylic acids substituted with one or two hydroxyl groups, preferably one hydroxyl group.

[0144] According to certain embodiments, the carboxylic acid may optionally be a hydroxylated carboxylic acid as a mixture with an unsubstituted carboxylic acid. Suitable examples of hydroxylated carboxylic acids include 12-hydroxystearic acid (12-HSA), 9-hydroxystearic acid (9-HSA), 10-hydroxystearic acid (10-HSA), 14-hydroxyicosanoic acid (14-HEA), 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butyric acid, hydroxyacetic acid (or glycolic acid), 2-hydroxypropionic acid (lactic acid), 2-hydroxy-3-(3-pyridyl)propionic acid, 3-hydroxybutyric acid, 2-hydroxybutyric acid, 2-methyl-2-hydroxybutyric acid, 2-ethyl-2-hydroxybutyric acid, hydroxypentanoic acid, hydroxyhexanoic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, hydroxynonanoic acid, hydroxydecanoic acid, and mixtures thereof, preferably 12-hydroxystearic acid or a binary or ternary mixture of 12-hydroxystearic acid and other hydroxylated acids.

[0145] Suitable examples of unsubstituted carboxylic acids include acetic acid, propionic acid, butyric acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, eicosanoic acid, palmitoleic acid, oleic acid, 11-eicosenoic acid, erucic acid, nervonic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, dihomo-γ-linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and mixtures thereof, preferably decanoic acid.

[0146] Preferably, the amide wax is C2-C 22 Carboxylic acids, especially hydroxylated C2-C222 Carboxylic acids, and optionally unsubstituted C2-C2 22 Carboxylic acids, more specifically hydroxylated C 12 ~C 20 Carboxylic acids, and optionally unsubstituted C2-C2 14 The present invention includes a diamide obtained from at least one carboxylic acid selected from carboxylic acids.

[0147] According to a preferred embodiment, the amide wax includes a diamide obtained by the reaction of 1,2-ethylenediamine or 1,6-hexamethylenediamine with 12-hydroxystearic acid or optionally decanoic acid.

[0148] Amide waxes can be compounds prepared by the reaction of ammonia or ethylenediamine with saturated and / or unsaturated fatty acids such as stearic acid, animal fat fatty acids, palmitic acid, or erucic acid. Amide waxes may also include amide compounds such as N,N'-ethylenedistearamid. For example, such a wax is "Crayvallac WN1265(R)" sold by Arkema.

[0149] According to one embodiment, polyolefin wax can be mixed with amide wax. For example, such waxes are "Crayvallac WN1135(R)" sold by Arkema or "Ceridust 9615A(R)" sold by Clariant (a mixture of polyethylene wax and amide wax).

[0150] According to one embodiment, the wax can be selected from fatty acid derivatives, such as partially or completely esterified fatty acids. Preferably, they are fatty acids containing at least 10 carbon atoms, preferably 16 to 60 carbon atoms, and more preferably 24 to 36 carbon atoms. Preferably, they are saturated alkane monocarboxylic acids, preferably linear, such as montanic acid. An example of this type of wax is the wax "Ceridust 5551(R)" sold by Clariant.

[0151] In the context of this invention, the wax does not contain a salt of a fatty acid (also called a "metal soap") containing at least 10 carbon atoms, preferably 16 to 60 carbon atoms, and more preferably 24 to 36 carbon atoms.

[0152] Typically, these are salts of saturated alkane monocarboxylic acids, preferably linear, such as montanic acid and stearic acid. Typically, they are salts of calcium and / or sodium and / or magnesium. For example, such waxes are Licomont NAV101(R), a wax sold by Clariant, and calcium stearate and / or magnesium stearate. It has been observed that using such salts as waxes in combination with semicrystalline thermoplastic polymer powders, particularly elastomer polymer powders, such as PEBA copolymer powder, does not increase the working window or ensure good cohesiveness of the layers.

[0153] However, it is possible to use such salts as additives in the scTP polymer powder used for sintering, for example, to improve flow, as described in US2006 / 0189784, or to reduce thermal stress during sintering, as described in US2008 / 0300353.

[0154] According to one embodiment, the wax in the composition of the present invention is nonionic.

[0155] The wax may be a mixture of functionalized ester wax and alcohol. An example is "Licolub WE40(R)" wax sold by Clariant.

[0156] Vegetable waxes may include, for example, derivatives of functionalized or unfunctionalized castor oil. Examples of castor oil-derived waxes include "Crayvallac PC(R)" sold by Arkema and "Jagrowax 100(R)" sold by Jayant Agro-Organics.

[0157] According to the present invention, the wax has a dropping point higher than the crystallization temperature (Ct) of the scTP polymer.

[0158] The term "dropping point" is understood to mean the temperature at which a wax changes from a semi-solid state to a liquid state under specific test conditions. The dropping point is measured according to the standard ASTM D3954-1994 (2004).

[0159] Preferably, the wax according to the present invention can have a dropping point up to 30°C, preferably up to 20°C, higher than the Mp of the scTP polymer. For example, this difference may be 1-5°C, or 5-10°C, or 10-15°C, or 15-20°C, or 20-25°C, or 25-30°C.

[0160] In particular, the wax may have a dropping point of 60 to 180°C, preferably 80 to 175°C. For example, this dropping point can be 60-65°C, or 65-70°C, or 70-75°C, or 75-80°C, or 80-85°C, or 85-90°C, or 90-95°C, or 95-100°C, or 100-105°C, or 105-110°C, or 110-115°C, or 115-120°C, or 120-125°C, or 125-130°C, or 130-135°C, or 135-140°C, or 140-145°C, or 145-150°C, or 150-155°C, or 155-160°C, or 160-165°C, or 165-170°C, or 170-175°C, or 175-180°C.

[0161] This invention proposes the use of a specific wax whose dropping point is higher than that of the scTP polymer's Ct. Thus, the wax is in a molten or at least partially molten state at the temperature of the powder layer, and a kind of tackiness can increase the cohesiveness of the scTP polymer powder, which results in increased rigidity of the powder layer and prevents parts from sinking into the layer.

[0162] Typically, the dropping point of the wax is at least 5°C, preferably at least 10°C, preferably at least 15°C, and more preferably at least 20°C higher than the Ct of the scTP polymer. For example, this temperature difference can be 5-10°C, or 10-15°C, or 15-20°C, or 20-25°C, or 25-30°C, or 30-35°C, or 35-40°C, or 40-45°C, or 45-50°C.

[0163] <Powdered composition> According to the present invention, the powder composition is semi-crystalline; that is, the conversion of the scTP polymer into powder and the preparation of the composition as powder do not affect the semi-crystalline properties of the scTP polymer as described above.

[0164] The composition according to the present invention preferably contains 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, 99% or more, 99.1% or more, 99.2% or more, and 99.3% or more. The above may contain scTP polymer(s) in weight ratios of 99.4% or more, 99.5% or more, 99.6% or more, 99.7% or more, 99.8% or more, 99.9% or more, 99.91% or more, 99.92% or more, 99.93% or more, 99.94% or more, 99.95% or more, 99.96% or more, 99.97% or more, 99.98% or more, and 99.99% or more.

[0165] Typically, scTP polymer particles can have a size Dv50 of 40–150 μm, preferably 50–100 μm. For example, the size Dv50 of scTP polymer particles can be 40-45 μm, or 45-50 μm, or 50-55 μm, or 55-60 μm, or 60-65 μm, or 65-70 μm, or 70-75 μm, or 75-80 μm, or 80-85 μm, or 85-90 μm, or 90-95 μm, or 95-100 μm, or 100-105 μm, or 105-110 μm, or 110-115 μm, or 115-120 μm, or 120-125 μm, or 125-130 μm, or 130-135 μm, or 135-140 μm, or 140-145 μm, or 145-150 μm.

[0166] Typically, the composition contains wax in a content of 0.1% to 20% by weight, preferably 0.5% to 10% by weight, and more preferably 0.5% to 5% by weight of the total composition. Thus, this content can be 0.1% to 0.2%, or 0.2% to 0.3%, or 0.3% to 0.4%, or 0.4% to 0.5%, or 0.5% to 1%, or 1% to 2%, or 2% to 4%, or 4% to 6%, or 6% to 8%, or 8% to 10%, or 10% to 12%, or 12% to 14%, or 14% to 16%, or 16% to 18%, or 18% to 20%.

[0167] Wax can be present in the composition in the form of wax particles. Typically, the wax particles have an average size (Dv50) of 1 to 30 μm, preferably 1 to 20 μm, and more preferably 5 to 15 μm.

[0168] Preferably, a wax is selected in which its average size (Dv50) is smaller than the average size of the scTP polymer in the composition.

[0169] The wax can also have a size Dv90 of less than 50 μm, preferably less than 20 μm. For example, the size Dv90 of the wax particles can be 5 to 20 μm, or 5 to 15 μm.

[0170] In connection with this patent application, - Dv50 is a particle size threshold, corresponding to the particle size threshold where 50% of particles (per volume) are smaller than this threshold, and 50% of particles (per volume) are larger than this threshold. - Dv90 is a particle size threshold, corresponding to the particle size threshold where 90% of particles (volume) are smaller than this threshold and 10% of particles (volume) are larger than this threshold.

[0171] Dv50 and Dv90 are measured according to ISO 9276 - Parts 1-6, "Representation of results of particle size analysis". For example, the volume distribution of the powder can be obtained using a laser particle sorter (Sympatec Helos) and software (Fraunhofer), and Dv50 and Dv90 can be estimated from there.

[0172] According to one embodiment, the wax is present in the composition in the form of a film that at least partially covers the particles of the scTP polymer powder.

[0173] <Flowing agent> According to one embodiment, the composition according to the present invention comprises one or more fluidizing agents.

[0174] The term "fluidizer" is understood to refer to a substance that allows for the improvement of fluidity, as well as leveling, of semi-crystalline thermoplastic polymer powders during the sintering process.

[0175] The presence of fluids in scTP polymer-based compositions has been observed to reduce the working window and make construction more difficult. Furthermore, problems with layer cohesiveness are more frequently encountered when fluids are used.

[0176] The use of wax in the compositions of the present invention proves particularly advantageous in these cases. That is, the use of wax allows for a wider working window and avoids the problem of layer aggregation, and therefore makes construction easier.

[0177] The fluidizing agent can be selected from those commonly used in the field of sintering scTP polymer powders. For example, it can be selected from silica, especially precipitated silica, hydrated silica, glassy silica, fumed silica, or calcined silica; glassy oxides, especially glassy phosphates or glassy borates; alumina, such as amorphous alumina, TiO2, calcium silicates, magnesium silicates, such as talc, mica, kaolin, attapulgite, and mixtures thereof.

[0178] The fluidizing agent is generally present in the composition in an amount of 5% by weight or less, preferably 3% or less, of the total composition. Typically, this content can be 0.1% to 2.5%, for example, 0.1% to 2%, preferably 0.5% to 2%, or 0.5% to 1.5%.

[0179] The fluidizing agent is generally in the form of a powder, preferably substantially spherical.

[0180] The fluidizing agent in the powder composition may be in the form of particles having an average size (Dv50) of 20 μm or less, preferably 15 μm or less, preferably 10 μm or less, and more preferably 1 μm or less. For example, the particle size Dv50 of the fluidizing agent may be 10 nm to 100 nm, 100 nm to 1 μm, or 1 μm to 20 μm.

[0181] <Other additives> The compositions according to the present invention may include any type of additive suitable for scTP polymer powder used in sintering, particularly additives (in powder form or not) that contribute to improving the properties of the powder for use in agglomeration techniques, and / or additives that enable improvement of the properties of the manufactured three-dimensional parts, such as mechanical properties (e.g., modulus of elasticity, elongation at break, impact strength) or aesthetic properties (color).

[0182] In a favorable embodiment, the composition according to the present invention may include inorganic additives, such as carbonate-based inorganic substances, particularly calcium carbonate, magnesium carbonate, dolomite or calcite, barium sulfate, calcium sulfate, dolomite, alumina hydrate, wollastonite, montmorillonite, zeolite, perlite, nanofillers (fillers on the nanometer scale), such as nanoclay, or carbon nanotubes, carbon black, glass fibers, carbon fibers, and organic additives, such as polymer powders having a melting point higher than the highest temperature experienced by the composition during the stratification process, particularly those having an elastic modulus greater than 1000 MPa. In one embodiment, the composition does not contain inorganic or organic additives.

[0183] The above types of additives may be present in the powder composition (including, as appropriate, those present in the scTP polymer powder) at a content of 60% by weight or less, preferably 30% by weight or less, more preferably 1% by weight or less, for example, 0.05% to 60% by weight, or 1% to 30% by weight, or 1% to 20% by weight, or 1% to 10% by weight.

[0184] The compositions of the present invention may also include dyes, colorants, infrared absorbers, fire-resistant additives, stabilizers, antioxidants, light stabilizers, impact modifiers, antistatic agents, flame retardants, and mixtures thereof. These additives are preferably in the form of powders with a Dv50 of less than 20 μm. These additives may be present in the composition at a content of 0.05 to 5%.

[0185] The additive can be mixed with the scTP polymer before and / or after the grinding step described above.

[0186] <Method for preparing the composition> The composition according to the present invention comprises a semicrystalline thermoplastic polymer and at least one wax powder.

[0187] A method for preparing the composition of the present invention includes the step of contacting the scTP polymer with a wax and optionally a fluidizing agent.

[0188] The scTP polymers that can be used in connection with the present invention are mostly commercially available, particularly in the form of granules, flakes, or coarse powders, and can be easily converted to powder by known methods.

[0189] Generally, scTP polymer powder can be obtained by grinding methods.

[0190] Preferably, the scTP polymer in contact with the wax is in the form of a powder, or, for example, granules, flakes, or coarse powder having a Dv50 size greater than 250 μm (in which case grinding and / or sieving steps can be performed).

[0191] According to one embodiment, the operation of contacting the scTP polymer with the wax is carried out by dry mixing, i.e., mixing in the absence of a solvent.

[0192] According to one embodiment, the operation of contacting the scTP polymer with wax is carried out according to the following steps. - By dissolving the wax in a suitable solvent to form a wax solution, - By mixing the wax solution with the scTP polymer to form a dispersion, and - For example, by removing the solvent from the dispersion by evaporation to obtain a wax-coated scTP polymer.

[0193] A suitable solvent may be a solvent known to those skilled in the art to be able to dissolve wax, such as acetone, ethanol, and / or a solvent comprising water and a surfactant.

[0194] The preparation method may include a grinding step to obtain scTP polymer powder having a desired particle size.

[0195] The grinding step can be performed before and / or after contacting the scTP polymer with the wax.

[0196] Preferably, the grinding is low-temperature grinding as known to those skilled in the art. Therefore, in the first step, the scTP polymer (or a mixture of scTP polymer and wax) is cooled to a temperature below the glass transition temperature of the scTP polymer. This temperature can be 10 to 50°C lower than the glass transition temperature of the scTP polymer. Thus, the mixture can be cooled to a temperature of -10°C or lower, preferably -50°C or lower, and more preferably -80°C or lower.

[0197] The scTP polymer (or a mixture of scTP polymer and wax) can be cooled, for example, using liquid nitrogen, liquid carbon dioxide, dry ice, or liquid helium.

[0198] The grinding stage can be carried out using a pin mill, hammer mill, or whirl mill.

[0199] The method for preparing the composition according to the present invention may subsequently include a sieving step. The sieving can be performed on a sieve.

[0200] Alternatively, after grinding, the preparation method may include a selection step to obtain a desired particle size profile. Typically, the powder is dispersed by a selection wheel and transported by classified air. Dust mixed into the air is transported via a support wheel and discharged through a first outlet. The crude product is rejected by the classification wheel and transported to a second outlet. The sorter may be equipped with multiple sequential wheels operating in parallel.

[0201] If the above-mentioned additive (including the fluidizing agent) is present in the composition, the scTP polymer (or a mixture of the scTP polymer and wax) is brought into contact with the additive in powder form (i.e., in the form of a simple mixture) before or after the grinding and / or sieving stage.

[0202] In certain forms, certain additives, such as inorganic additives, can be incorporated into scTP polymer powder by compounding, particularly during the manufacturing stage of scTP polymer granules intended for grinding.

[0203] Furthermore, for certain scTP polymers, such as polyamides, a dissolution-precipitation method can be considered for powder preparation. In this special case, wax can be introduced during the dissolution-precipitation process.

[0204] <Method for sintering compositions> The above composition is used in a method for constructing 3D articles layer by layer by sintering, which is brought about by electromagnetic radiation, such as infrared radiation or ultraviolet radiation, or preferably by a laser.

[0205] In this method, a thin layer of powder is deposited on a horizontal plate maintained in a chamber heated to a temperature called the construction temperature. The "construction temperature" (also called the "layer temperature") represents the temperature at which the powder layers of the constituent layers of the three-dimensional object being constructed are heated during the sintering process of each powder layer. This temperature can be less than 50°C, preferably less than 40°C, and more preferably about 20°C lower than the melting point of the scTP polymer. Electromagnetic radiation then contributes to the energy required to sinter the powder particles at different points in the powder layer according to the geometry corresponding to the object (for example, using a computer with the shape of the object in memory and reproducing the shape of the object in the form of slices).

[0206] Next, the horizontal plate is lowered by a value corresponding to the thickness of the powder layer, and a new layer is deposited. Electromagnetic radiation contributes to the energy required to sinter the powder particles according to the geometric shape corresponding to this new slice of the object. This procedure is repeated until the object is manufactured.

[0207] Preferably, the powder layer deposited on the horizontal plate (before sintering) can have a thickness of 20 to 200 μm, preferably 50 to 150 μm. After sintering, the aggregated material layer can have a thickness of 10 to 150 μm, preferably 30 to 100 μm.

[0208] Preferably, the composition of the present invention is used in selective laser sintering (SLS) methods. This composition can also be used in MJF (multi-jet fusion) and HSS (high-speed sintering) type sintering methods.

[0209] Thus, the powder composition according to the present invention makes it possible to manufacture high-quality three-dimensional articles that have good mechanical properties and accurate and clear dimensions and contours.

[0210] The above powder composition can be recycled and reused in several consecutive builds. It can be used, for example, as is or as a mixture with other powders (which may or may not be reused).

[0211] The following examples illustrate the present invention without limiting it. [Examples]

[0212] [Example 1] Various powders of PEBA copolymer are optionally mixed with a fluidizing agent (silica) at a concentration of 1% by weight (relative to polymer A) or 0% by weight (relative to polymer B), and optionally mixed with wax at a concentration of 1% by weight.

[0213] The following table lists the different PEBAs used in connection with this example.

[0214] [Table 1]

[0215] Therefore, polymers A and B were mixed with a fluidizing agent and a wax to form compositions 1 to 11. These compositions were used in the manufacture of three-dimensional articles.

[0216] [Table 2]

[0217] It was observed that the presence of wax with a dropping point higher than the polymer's Ct allowed the composition to pass through the sintering machine to obtain a 3D article (Compositions 2-6 and 8). Without wax, the composition could not pass through the sintering machine (Compositions 1 and 7). In the case of composition 9, it was found that if the dropping point of the wax was lower than the polymer's Ct, the 3D article could not be manufactured.

[0218] In the case of compositions 10 and 11 that do not contain wax, it was found that the use of salt could not increase the working window or ensure the cohesiveness of the layers, making it impossible to manufacture 3D articles.

[0219] [Example 2] PA12 powder is mixed with silica at a content of 0.15%. This powder has an Mp equal to 180°C and a Ct equal to 147°C, which are measured according to standard ISO 11357.

[0220] To form compositions 1 and 2, this powder was dry-mixed with wax. These compositions were used in the manufacture of three-dimensional articles.

[0221] The wax used is polyhydroxyalkanoate (PHA), which is sold by BYK under the trademark Ceraflour 1000(R).

[0222] [Table 3]

[0223] Determine the work window for compositions 1 and 2.

[0224] [Table 4]

[0225] For composition 1, part settling is observed below 160°C. Composition 2 allows for the construction of three-dimensional objects over a wider temperature range. Therefore, this formulation has a larger working window. Furthermore, it was observed that the addition of wax promotes polymer crystallization, i.e., the crystallization temperature is higher. This effect can be seen by melting the polymer at 220°C and then observing isothermal crystallization in DSC at 160°C. It can be seen that the crystallization rate of composition 2 is higher than that of composition 1 without wax. Surprisingly, even with a higher crystallization temperature, the presence of wax makes printing possible below 160°C.

Claims

1. A composition for constructing three-dimensional (3D) articles layer by layer by sintering of a composition brought about by electromagnetic radiation, - Semi-crystalline thermoplastic polymer powder, - A wax having a dropping point higher than the crystallization temperature (Ct) of the semicrystalline thermoplastic polymer. - and optional fluids Includes, The wax does not contain a salt of a fatty acid containing at least 10 carbon atoms. The semi-crystalline thermoplastic polymer is an elastomer selected from a copolymer containing a polyamide block and a polyether block (PEBA), a thermoplastic polyurethane (TPU), a copolymer containing a polyester block and a polyether block (COPE), and mixtures thereof. composition.

2. The composition according to claim 1, wherein the wax is selected from polyolefin waxes, plant-derived or animal-derived waxes, and mixtures thereof.

3. The composition according to claim 2, wherein the wax is selected from polyethylene wax and polypropylene wax, polytetrafluoroethylene wax, ketone wax, acid wax, partially esterified acid wax, acid anhydride wax, ester wax, aldehyde wax, amide wax, derivatives thereof, and mixtures thereof.

4. The composition according to any one of claims 1 to 3, wherein the PEBA polyamide block is selected from polyamide (PA) 11, PA12, or PA6.

5. The composition according to any one of claims 1 to 3, wherein the PEBA polyamide block is a PA6, PA11, PA12, PA610, PA1010 or PA1012 block, and / or the PEBA polyether block is a block derived from PEG (polyethylene glycol), PPG (propylene glycol), PO3G (polytrimethylene glycol) or PTMG (polytetrahydrofuran).

6. The composition according to any one of claims 1 to 5, wherein the wax is present in an amount of 0.1% to 20% by weight of the total composition.

7. The composition according to any one of claims 1 to 6, wherein the dropping point of the wax is at least 5°C higher than the crystallization temperature of the semicrystalline thermoplastic polymer.

8. The composition according to any one of claims 1 to 7, wherein the dropping point of the wax is up to 30°C higher than the melting point of the semicrystalline thermoplastic polymer.

9. The composition according to claim 1, wherein the fluidizing agent is present in an amount of 5% by weight or less of the total composition.

10. The aforementioned fluid agent is silica, glassy oxide, alumina, TiO ２ The composition according to claim 9, selected from calcium silicate, magnesium silicate, mica, kaolin, attapulgite, and mixtures thereof.

11. Use of the composition according to any one of claims 1 to 10 for the construction of a 3D article layer by layer by sintering of the composition brought about by electromagnetic radiation.

12. The use according to claim 11, wherein the composition is reused in several successive constructions.

13. A 3D article manufactured from the composition described in any one of claims 1 to 10.

14. Use of wax to enhance the cohesiveness of a layer of semicrystalline thermoplastic polymer powder in a sintering process by electromagnetic radiation, wherein the wax and / or semicrystalline thermoplastic polymer is as defined in any one of claims 1 to 10.

15. Use of wax in a semicrystalline thermoplastic-based powder composition for improving the recyclability of powder in a sintered 3D article structure, wherein the wax and / or semicrystalline thermoplastic polymer is as defined in any one of claims 1 to 10.

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