Polyaryletherketone-based powders for the production of ductile objects

Abstract

The present invention relates to a powder comprising particles of a composition comprising at least one polyaryletherketone and at least one flexible thermoplastic polymer. The elastic modulus of the flexible thermoplastic polymer is at least two times lower than that of the polyaryletherketone. The polyaryletherketone forms a matrix in which the flexible thermoplastic polymer is dispersed. The powder particles have a volume-weighted particle size distribution with a median diameter d50 strictly less than 500 μm. The invention also relates to a method for producing the powder, to the use of the powder and to objects obtained therefrom.

Description

[Technical field]

[0001] The present invention relates to the field of polyaryletherketones.

[0002] More particularly, the invention relates to powders based on polyaryletherketones for the production of ductile objects, in particular for the production of objects by layer-by-layer construction methods by electromagnetic radiation mediated sintering. [Background technology]

[0003] Polyaryletherketones (PAEKs) are well-known high-performance engineering polymers. They can be used in applications with severe temperature and / or mechanical or even chemical constraints. They can also be used in applications that require good fire resistance and low emissions of gases and toxic fumes. Finally, they are biocompatible. These polymers are found in a variety of fields, including aerospace, offshore drilling, automotive, rail, marine, wind power, sports, construction, electronics, medical implants, and many more.

[0004] Despite these advantageous properties, polyaryletherketones may need to be compounded to meet certain specifications. Thus, greater flexibility is required to accommodate new methods for using and installing parts with greater bending processability. In particular, polyaryletherketone compounds may be required to be more ductile, i.e., to exhibit greater deformation at break and / or to exhibit lower tensile / flexural modulus and / or higher impact strength compared to uncompounded PAEK.

[0005] For example, a composition consisting of polyetheretherketone (PEEK) and polyoctenylene is known from US Patent Application Publication No. 2009 / 0292073.

[0006] A composition consisting of polyetheretherketone (PEEK) and polysiloxane is also known from US Patent Application Publication No. 2005 / 004326.

[0007] A composition consisting of a mixture of PEEK and a polysiloxane / polyetherimide block copolymer is further known from US Patent Application Publication No. 2010 / 0147548. More specifically, a non-strippable mixture has been produced which contains PEEK and 10% to 25% by weight of a polysiloxane / polyetherimide block copolymer containing 20% ​​to 30% by weight of polysiloxane (see in particular Table 2 of the patent document).

[0008] A composition consisting of a mixture of PEEK, polyetherimide and a polysiloxane / polyetherimide block copolymer is also known from EP-A-0 323 142.

[0009] Compositions consisting of a mixture of PEEK and i) a copolymer consisting of repeating units derived from tetrafluoroethylene and propylene, or ii) a copolymer consisting of repeating units derived from hexafluoropropylene and vinylidene are also known in US Patent Application Publication No. 2019 / 0055390.

[0010] Finally, a composition consisting of a mixture of PEKK, polysiloxane / polyetherimide block copolymer and polysiloxane is known from EP 3749714. In this patent document, the use of this composition in the form of a powder is specified, but no embodiment is detailed. It is only indicated that such a powder can be obtained according to a standard grinding process. However, as will be explained below, the existing grinding process, which is already complicated to carry out for pure polyaryletherketone compositions, turns out to be practically impossible for more ductile compositions.

[0011] In particular, this is why none of the above mentioned patents use powder production procedures: all the mixtures are obtained by compounding, a process aimed at obtaining homogeneous granules of the selected composition, which are then used to form the final object by various processes, in particular extrusion and injection molding.

[0012] The methods commonly used to produce polyaryletherketone-based powders are milling methods, which have in common the feature that the material to be milled must be rendered friable enough to permit milling.

[0013] For example, it is known from US Patent Application Publication No. 2009280263 to grind coarse particles of polyetheretherketone under cryogenic conditions. In particular, the reduction in temperature makes the material more brittle. This process has been found to be ineffective for granules of ductile compositions based on polyaryletherketone.

[0014] Grinding coarse particles of polyetheretherketone at room temperature is also known from EP 2776224, starting from particles with a sufficiently low tapping density and therefore concomitantly a sufficiently high porosity. Granules of ductile compositions based on polyaryletherketone are too dense for use in room temperature grinding processes. Furthermore, a method for obtaining coarse particles of ductile compositions based on polyaryletherketone with a sufficiently low density is currently unknown.

[0015] Finally, in WO 21069833, it is known to grind coarse particles of polyetherketoneketone with talc-type fillers, thereby making them more brittle. However, the addition of such fillers has the effect of increasing the elastic modulus of the composition, which is contrary to the effect sought in the present invention.

[0016] Thus, none of the above mentioned grinding methods is suitable for providing fine powders from ductile compositions based on polyaryletherketones, i.e. in particular powders having a volume-weighted particle size distribution with a median size strictly less than 500 μm.

[0017] However, currently there exists a need to provide such powders of ductile composition for processes for the manufacture of articles that use compositions in powder form. One example of a process, which is particularly detailed below in this application, is a layer-by-layer construction process of an object by electromagnetic radiation mediated sintering. Other examples of processes requiring compositions in powder form are, for example, powder coating of metals, powder compression molding or powder compression-transfer molding. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] US Patent Application Publication No. 2009 / 0292073 [Patent Document 2] US Patent Application Publication No. 2005 / 004326 [Patent Document 3] US Patent Application Publication No. 2010 / 0147548 [Patent Document 4] European Patent Application Publication No. 0323142 [Patent Document 5] US Patent Application Publication No. 2019 / 0055390 [Patent Document 6] European Patent Application Publication No. 3749714 [Patent Document 7] US Patent Application Publication No. 2009280263 [Patent Document 8] European Patent No. 2776224 [Patent Document 9] International Publication No. 21069833 [Patent Document 10] European Patent No. 0945173 [Patent Document 11] International Publication No. 2012 / 047613 Summary of the Invention [Problem to be solved by the invention]

[0019] One object of the present invention is to provide a method for obtaining fine powders of ductile compositions based on polyaryletherketones, and to provide such powders which could not be used in the prior art.

[0020] Another object of the present invention, at least according to certain embodiments, is to provide a powder and a method for its manufacture, which powder is suitable for use in a layer-by-layer method of building an object by electromagnetic radiation mediated sintering.

[0021] Another object of the present invention, at least according to certain embodiments, is to provide a powder and a method for its manufacture, which is suitable for use in a coating process, a powder compression molding process, or a powder compression-transfer molding process using the powder.

[0022] Another object of the present invention, at least according to certain embodiments, is to provide a powder having a high density.

[0023] Another object of the present invention, at least according to certain embodiments, is to provide a powder that has good powder flowability.

[0024] Another object of the present invention, at least according to certain embodiments, is to provide a powder that is at least partially crystalline.

[0025] Finally, one object of the present invention is to provide objects having better ductility and / or better impact strength compared to objects obtained from unformulated polyaryletherketone, in particular polyaryletherketone alone. [Means for solving the problem]

[0026] The present invention relates to a powder comprising particles of a composition comprising at least one polyaryletherketone and at least one flexible thermoplastic polymer that is not a polyaryletherketone, the elastic modulus of said at least one flexible thermoplastic polymer being at least two times lower than that of said at least one polyaryletherketone, measured at 23° C. on 1BA specimens obtained by injection molding at a crosshead speed of 1 mm / min according to the ISO 527-2:2012 standard. The polyaryletherketone forms the matrix in which said flexible thermoplastic polymer is dispersed. Finally, the particles of the composition as described above have a volume-weighted particle size distribution with a median diameter d50 strictly less than 500 μm, preferably less than or equal to 300 μm, measured by laser diffraction according to the ISO 13320:2009 standard.

[0027] The inventors have unexpectedly succeeded in producing a powder comprising particles of a composition in which at least one flexible thermoplastic polymer is dispersed in a matrix comprising at least one polyaryletherketone, something that has never before been possible with the various grinding techniques commonly used.

[0028] this is, - providing a composition in a molten state comprising a flexible thermoplastic polymer dispersed in a polymer matrix comprising a polyaryletherketone; - atomizing said composition in a molten state to form droplets of the molten composition; - cooling the droplets of the molten composition to form solid particles; and - optionally one or more heat treatment steps, This has been achieved by using a manufacturing method according to the present invention, which comprises:

[0029] The inventors have now surprisingly observed that this melt spraying process can be carried out without particular difficulty on mixtures of polymers to obtain particles consisting of a dispersion of one polymer in the other.

[0030] According to certain embodiments, the flexible thermoplastic polymer may have a modulus of elasticity of less than or equal to 1.5 GPa at 23° C., measured on 1BA test specimens obtained by injection molding according to the ISO 527-2:2012 standard.

[0031] According to a particular embodiment, the flexible thermoplastic polymer may be selected from the list consisting of linear polyenes, polysiloxanes, polysiloxane block copolymers, fluoroelastomers comprising at least one repeat unit derived from tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride and chlorotrifluoroethylene, and mixtures of these polymers.

[0032] Fluoroelastomers are in particular those which have repeating units derived from tetrafluoroethylene and have the chemical formula CF2=C(F)(R) (Wherein, R represents a -CF group or a -OR group, R is C 1~5 (perfluoroalkyl) or a copolymer consisting essentially of, or consisting of, repeat units derived from monomers of Preferentially, said fluoroelastomer may consist essentially of or consist of repeating units deriving from tetrafluoroethylene and repeating units deriving from hexafluoropropylene.

[0033] Block copolymers containing polysiloxane blocks are particularly preferred in which the polysiloxane blocks are preferentially C1-C 12 mono- or di-substituted with alkyl groups and / or phenyl groups optionally substituted with one or more functional groups; and the blocks of units other than polysiloxane may preferentially be polyetherimide, polyaryletherketone, polyarylethersulfone, poly(phenylene sulfide), polyarylamideimide, polyphenylene, polybenzimidazole and / or polycarbonate blocks, or may be copolymers.

[0034] According to a particular embodiment, the flexible thermoplastic polymer may represent in total between 5% and 40% by weight, preferentially between 7% and 25% by weight, relative to the total weight of the flexible thermoplastic polymer and the polyaryletherketone of the composition.

[0035] According to certain embodiments, the combined weight of the polyaryletherketone and flexible thermoplastic polymer may represent at least 85%, or at least 90%, or at least 92.5%, or at least 95%, or at least 97.5%, or at least 98%, or at least 98.5%, or at least 99%, or at least 99.5%, or 100%, based on the total weight of the composition.

[0036] In certain embodiments, the composition may comprise a polyaryletherketone, a flexible thermoplastic polymer, optionally a polymer other than the polyaryletherketone and the flexible thermoplastic polymer, which is miscible with the polyaryletherketone, and optionally one or more functional additives.

[0037] In certain embodiments, the powder particles may have a volume weighted particle size distribution with a median diameter d50 in the range of 40 to 140 micrometers, preferably in the range of 50 to 120 micrometers, and more preferably in the range of 60 to 110 micrometers, as measured by laser diffraction according to the ISO 13320:2009 standard.

[0038] According to certain embodiments, the powder may have particularly advantageous tapping density and / or powder pourability.

[0039] In particular, 500kg / m2 when measured according to the ISO1068:1975 standard 3 The tapping density can be equal to or greater than 100 .mu.m.

[0040] In particular, it may have a powder flowability of 10 seconds or less, preferentially 7 seconds or less, very preferably 5 seconds or less, when measured according to method "A" of the ISO 6186:1998 standard, and the powder further does not comprise a powder flow agent.

[0041] According to certain embodiments, especially when the method is carried out without an additional heat treatment step, the powder may be in amorphous form.

[0042] According to certain other embodiments, the powder may be in crystalline form, especially when the method is carried out with at least one heat treatment step.

[0043] In particular, it may have a degree of crystallinity, measured by X-ray diffraction, of greater than or equal to 10% by weight, preferentially greater than or equal to 15%, more preferably greater than or equal to 15%, relative to the total weight of polymers in the composition.

[0044] According to a particular embodiment, said at least one polyaryletherketone is a polyetherketoneketone, preferentially consisting essentially of terephthalic and optionally isophthalic units, more preferably consisting of terephthalic and optionally isophthalic units, the terephthalic units (T) being

[0045] [ka]

[0046] and the isophthalic unit (I) is

[0047] [ka]

[0048] and the molar ratio of T:I ranges from 0:100 to 85:15.

[0049] The invention also relates to the use of such powders in processes for the layer-by-layer building of objects by electromagnetic radiation mediated sintering, powder coating, powder compression moulding or powder compression-transfer moulding processes.

[0050] Finally, the invention relates to objects based on polyaryletherketones, obtained by one of the manufacturing methods mentioned above, namely a method which requires the use of materials in powder form.The invention particularly relates to objects obtained by a layer-by-layer construction method of the object by electromagnetic radiation mediated sintering.

[0051] The object according to the invention has mechanical properties that were previously unobtainable due to the fact that the person skilled in the art has until now been unable to use a powder comprising at least one flexible thermoplastic polymer dispersed in a matrix of polyaryletherketone.

[0052] According to certain embodiments, the object may have an elastic modulus strictly less than 4 GPa, as measured on a 1BA specimen at 23° C. according to the ISO 527-1:2019 standard.

[0053] According to a particular embodiment, the object has a thermal resistance of 5 kJ / m2 for a type A notched bar according to the ISO 179:2010 standard. 2 Above 6kJ / m 2 Above 7kJ / m 2 Above 8kJ / m 2 More than 9 kJ / m, most preferably 2 It can have a Charpy impact strength of at least 1000 MPa.

[0054] The present invention will be better understood in light of the following detailed description of non-limiting embodiments and the following figures. [Brief description of the drawings]

[0055] [Figure 1] FIG. 1 shows a schematic representation of an apparatus for carrying out a method for the layer-by-layer building of a three-dimensional object by sintering, in which the powder according to the invention can be used. [Diagram 2] FIG. 1 is a schematic diagram of a melt spray device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056] definition The term "thermoplastic polymer" is understood to mean a polymer that becomes less viscous or becomes liquid when heated sufficiently and reversibly retains thermoplastic properties. Thermoplastic polymers are generally contrasted with thermosetting polymers, which are irreversibly transformed into an insoluble polymer network and cannot be thermoformed.

[0057] The term "homopolymer" is understood to denote a polymer consisting of a single repeating unit.

[0058] The term "copolymer" is understood to denote a polymer resulting from the copolymerization of at least two chemically different monomers, called comonomers. A copolymer is thus formed from at least two different repeat units derived from different monomers. It may also be formed from three or more repeat units derived from different monomers.

[0059] The copolymers can have a uniform structure, in particular of the statistical type, alternating type, random type, or a heterogeneous structure, in particular of the block type.

[0060] In particular, the terms "sequential copolymer" or "block copolymer" are understood to denote a copolymer in the above sense in which at least two different homopolymer blocks are covalently linked. The length of the blocks can be variable. The blocks can each consist of 1 to 1000, preferably 1 to 100, in particular 1 to 50 repeat units. The bond between the two homopolymer blocks can be a simple covalent bond or an intermediate non-repeating unit known as a junction block.

[0061] The term "consisting essentially of a unit" is understood to mean that the unit makes up a molar proportion of 95% to 99.9% relative to the total number of moles of repeating units in the polymer.

[0062] The term "consisting of a unit" is understood to mean that the unit occupies a molar proportion in the polymer of at least 99.9%, in particular 100%, relative to the total number of moles of repeating units in the polymer.

[0063] The term "mixture of polymers" is understood to denote a macroscopically homogeneous composition of polymers. This term particularly encompasses such compositions consisting of mutually immiscible phases dispersed on the micrometer or submicrometer scale.

[0064] The term "dispersed" is intended to denote a composition consisting of several phases. In the mixture according to the invention, the polyaryletherketone forms the continuous phase or matrix and the flexible thermoplastic polymer forms the dispersed phase, generally in the form of nodules. The nodules have an average size preferentially less than or equal to 5 micrometers, more preferentially less than or equal to 2 micrometers.

[0065] The size of the flexible thermoplastic polymer nodules in the composition, in particular in the matrix based on polyaryletherketone, is evaluated by microscopic analysis and digital processing of cross sections of objects that can be produced by powder methods, in particular by layer-by-layer construction of objects by electromagnetic radiation mediated sintering. A scanning electron microscope (SEM) may be used. The images obtained are binarized, allowing the average and maximum size of the nodules to be determined.

[0066] The term "melting temperature" is intended to indicate the temperature at which an at least partially crystalline polymer changes into a viscous liquid state, as measured during the second heating by differential scanning calorimetry (DSC) according to the NF EN ISO11 357-3:2018 standard, using a heating rate of 20°C / min.

[0067] The term "glass transition temperature" is intended to indicate the temperature at which an at least partially amorphous polymer changes from a rubbery to a glassy state or vice versa, as measured during the second heating by differential scanning calorimetry (DSC) according to the NF EN ISO11 357-2:2020 standard, using a heating rate of 20°C / min.

[0068] Melting temperatures and glass transition temperatures are expressed in degrees Celsius (°C).

[0069] The term "crystallinity" is intended to indicate the degree of crystallinity calculated from wide-angle X-ray scattering (WAXS) measurements on a Nano-inXider® machine under the following conditions: - Wavelength: Main Kα1 line of copper (1.54 angstroms) - Generator output: 50kV-0.6mA - Observation mode: Transparent - Counting time: 10 minutes - Temperature: 25℃

[0070] A spectrum of scattering intensity as a function of diffraction angle is thus obtained. This spectrum makes it possible to confirm the presence of crystals if a peak is visible in the spectrum in addition to the amorphous halo. In the spectrum, the area of ​​the crystalline peak (designated A) and the area of ​​the amorphous halo (designated AH) can be measured. The (mass) proportion of the crystalline phase is estimated by the ratio (A) / (A+AH). The degree of crystallinity in the present invention is expressed as the mass proportion of crystalline polymer relative to the total mass of polymer in the composition.

[0071] The term "amorphous" is understood to mean that the composition has a crystallinity of less than or equal to 7%, preferentially less than or equal to 5%, and very preferably less than or equal to 3%. According to certain embodiments, an "amorphous" composition can have a crystallinity of approximately 0%.

[0072] The term "crystalline polymer" is understood to mean that the polymer is not amorphous, in which case it has a crystallinity strictly greater than 7%.

[0073] The term "viscosity" is intended to indicate the viscosity measured using an Anton Paar MCR302 oscillatory rheometer in plate / plate geometry, under an inert atmosphere (N2), at 380°C and 1 Hz.

[0074] The term "tensile modulus", or more simply "elastic modulus", is understood to mean the slope of the stress-strain curve σ(ε) in the interval between two strains ε1=0.05% and ε2=0.25%, as defined in the ISO 527-1:2019 standard. The modulus is expressed here in gigapascals (GPa). The slope is preferably measured by linear regression.

[0075] Although the modulus of elasticity is determined here by mechanical tensile stress, it is not outside the scope of the invention if it is measured from other types of stress, such as bending or compressive stress.

[0076] For commercially available materials of construction, the modulus is often available in the supplier's product data sheet. In the absence of available or predictable data, measurements of the tensile modulus can be performed on 1BA specimens at 23° C. with a crosshead speed of 1 mm / min. The actual measured value of the modulus corresponds to the average value of five consecutive tests. These tests can be performed, for example, using an MTS810® testing machine sold by MTS Systems Corporation equipped with a mechanical extensometer.

[0077] For the characterization of the tensile modulus of the composition, considering the powder and / or one of its constituents alone, 1BA test specimens are produced by injection molding according to the ASTM D3641-15 standard. The injection molding conditions are selected according to one of the following criteria, considered in the indicated order: the conditions imposed in the standard related to the material, the instructions given by the supplier, or, in their absence, the best available information on the polymer or related polymers.

[0078] For characterization of the elastic modulus of objects producible by powder methods, 1BA specimens are produced by said methods. For example, 1BA specimens can be produced by layer-by-layer construction methods of objects by electromagnetic radiation mediated sintering.

[0079] The term "powder" refers to a fractionated state of matter, generally in the form of particles of very small size, generally less than about 100 micrometers. The term "comminuted form" refers to a composition that is generally in the form of a powder.

[0080] Particle size distribution can be measured by laser diffraction method according to the ISO13320:2009 standard, for example using a Malvern Mastersizer2000® diffractometer. Rules for the presentation of particle size distribution results are described in the ISO9276 standard parts 1-6. The term "d50" is understood to mean the value of the diameter of the powder particles for which the cumulative function of the volume-weighted particle size distribution is equal to 50%. Similarly, the terms "d10" and "d90" respectively mean the corresponding diameters for which the cumulative function of the volume-weighted particle size distribution is equal to 10% and 90%, respectively.

[0081] The term "tapping density" is understood to mean the powder density value measured according to the ISO 1068:1975 standard. It can be measured with a STAV 2003 tapping volumeter equipped with a 250 ml cylinder after 2500 pulses. The unit is kilograms per cubic meter (kg / m 3 ) is displayed.

[0082] The term "powder flowability" is intended to indicate the ability of a powder to flow freely, uniformly and constantly in the form of individual particles. Powder flowability is measured here according to method "A" of the ISO 6186:1998 standard, using a funnel with an opening of 25 mm in diameter, allowing the ground composition to flow. Incidentally, no antistatic agents are added to the composition. Powder flowability is measured in seconds (s).

[0083] The term "Charpy impact strength" or more simply "impact strength" refers to the strength of a specimen measuring 80 x 10 x 4 mm in diameter, measured according to the ISO 179:2010 standard. 3 is understood to indicate the impact strength of a type A notched bar of 0.25 ± 0.05 mm. The actual measurement is the average of three tests carried out in succession. The notch (V-shaped, notch base radius 0.25 ± 0.05 mm) can be made with a device specially prepared for this purpose (Automatic Notchvis Plus sold by the company CEAST). The bar is then left to rest for 24 hours. The measurement of the impact strength can be carried out with a Zwick 5102 impact tester.

[0084] The singular forms "a(n)" and "the" as applied to components of the composition, such as the polyaryletherketone or flexible thermoplastic polymer, or properties of these components, by default mean "at least one" and "said at least one," respectively. Nevertheless, the singular forms include, without need for reminder each time, embodiments where "a(n)" means "only one" and "the" means "only one."

[0085] Ranges of values ​​stated in this patent application are inclusive of the limits unless otherwise stated.

[0086] Polyaryletherketone Polyaryletherketones (PAEKs) contain units of the formula: (-Ar-X-) and (-Ar1-Y-), Where: - Ar and Ar1 each represent a divalent aromatic radical; Ar and Ar1 may preferably be selected from 1,3-phenylene, 1,4-phenylene, divalent 1,1'-biphenylene in the 3,3' positions, divalent 1,1'-biphenyl in the 3,4' positions, 1,4-naphthylene, 1,5-naphthylene and 2,6-naphthylene; - X represents an electron-withdrawing group, which may preferably be chosen from carbonyl and sulfonyl groups; - Y represents a group selected from an oxygen atom, a sulfur atom, and an alkylene group such as -(CH)2-, isopropylidene, etc.

[0087] In these X and Y units, at least 50%, preferably at least 70%, more particularly at least 80% of the X groups are carbonyl groups and at least 50%, preferably at least 70%, more particularly at least 80% of the Y groups represent oxygen atoms.

[0088] According to a preferred embodiment, 100% of the X groups represent a carbonyl group and 100% of the Y groups represent an oxygen atom.

[0089] Advantageously, the PAEK may be chosen from: - polyetherketoneketone, also known as PEKK; PEKK contains one or more units of the formula: -Ph-O-Ph-C(O)-Ph-C(O)-; - Polyetheretherketone, also known as PEEK; PEEK contains one or more units of the formula: - Ph-O-Ph-O-Ph-C(O)-; - polyetherketone, also known as PEK; PEK contains one or more units of the formula: -Ph-O-Ph-C(O)-; - polyetheretherketoneketone, also known as PEEKK; PEEKK contains one or more units of the formula: - Ph-O-Ph-O-Ph-C(O)-Ph-C(O)-; - polyetheretheretherketone, also known as PEEEK; PEEEK contains one or more units of the formula: - Ph-O-Ph-O-Ph-O-Ph-C(O)-; - polyether diphenyl ether ketone, also known as PEDEK; PEDEK contains one or more units of the formula -Ph-O-Ph-Ph-O-Ph-C(O)-; - mixtures thereof; and - a copolymer comprising at least two of the above units, where Ph represents a phenylene group, -C(O)- represents a carbonyl group, and each phenylene can independently be in the ortho (1,2), meta (1,3) or para (1,4) form, and is preferentially in the meta or para form.

[0090] Additionally, defects, end groups and / or monomers can be incorporated into a polymer such as those listed above in very small amounts without affecting its performance.

[0091] Preferentially, in the embodiment in which the polyaryletherketone is a copolymer, the latter has a homogeneous structure, in particular of the statistical type.

[0092] According to a particular embodiment, the PAEK is a polyetherketoneketone consisting essentially and preferentially of terephthalic repeat units and, where appropriate, isophthalic repeat units, the terephthalic repeat units ("T units") being of the formula

[0093] [ka]

[0094] having An isophthalic repeating unit ("I unit") has the formula

[0095] [ka]

[0096] has.

[0097] The mass proportion of T units relative to the sum of T units and I units can vary from 0% to 85%. The mass proportion of T units relative to the sum of T units and I units can in particular be 0% to 5%; or 5% to 10%; or 10% to 15%; or 15% to 20%; or 15% to 20%; or 20% to 25%; or 25% to 30%; or 30% to 35%; or 35% to 40%; or 40% to 45%; or 45% to 50%; or 50% to 55%; or 55% to 60%; or 60% to 65%; or 65% to 70%; or 70% to 75%; or 75% to 80%; or 80% to 85%. The choice of the molar ratio of T units relative to the sum of T units and I units is one of the factors that makes it possible to adjust the ratio of the crystallization properties of the polyetherketoneketone. A given molar proportion of T units relative to the sum of T and I units can be obtained, in a manner known per se, by adjusting the respective concentrations of the reactants during the polymerization.

[0098] For the use of the powder in a method for layer-by-layer construction of an object by electromagnetic radiation mediated sintering, the mass proportion of T units with respect to the sum of T units and I units is preferentially 0% to 25% or 45% to 75%, more preferably 0% to 15% or 55% to 65%. The mass proportion of T units with respect to the sum of T units and I units may in particular be around 0% or around 60%.

[0099] Such polyaryletherketones are commercially available from Arkema under the name Kepstan®.

[0100] According to a particular embodiment, the PAEK has the formula

[0101] [ka]

[0102] It may be a homopolymer consisting essentially of, or further consisting of, repeat units having the formula:

[0103] Such polyaryletherketones are commercially available under the names KetaSpire® from Solvay, VestaKeep® from Evonik and PEEK Victrex® from Victrex.

[0104] According to a particular embodiment, the PAEK comprises repeat units having the formula (III) and

[0105] [ka]

[0106] and

[0107] The molar ratio of (III) units to the sum of (III) and (IV) units can range from 0% to 99%, preferentially from 0% to 95%.

[0108] According to a particular embodiment, the PAEK comprises repeat units having the formula (III) and

[0109] [ka]

[0110] and

[0111] The molar ratio of (III) units to the sum of (III) and (V) units can range from 0% to 99%, preferentially from 0% to 95%.

[0112] The melting temperature of the PAEK is preferably higher than 280°C, very particularly higher than 300°C.

[0113] The glass transition temperature of the PAEK is preferably between 100°C and 250°C, preferably between 120°C and 200°C, very particularly between 140°C and 180°C.

[0114] Advantageously, the PAEK has a viscosity, measured at 380° C. and 1 Hz, of more than 100 Pa·s, preferably more than 200 Pa·s, more preferably more than 300 Pa·s. The viscosity of the PAEK generally does not exceed 1500 Pa·s. The viscosity of the PAEK may in particular be between 300 Pa·s and 600 Pa·s, or between 600 Pa·s and 800 Pa·s, or between 800 Pa·s and 1000 Pa·s, or between 1000 Pa·s and 1200 Pa·s, or between 1200 Pa·s and 1500 Pa·s.

[0115] According to a particular embodiment, the composition comprises at least two PAEKs. The composition may in particular exclusively comprise a copolymer essentially consisting of or consisting of repeat units of formulae (I) and (II), or (III) and (IV), or alternatively (III) and (V), which constitutes at least 50% by weight, preferably at least 60%, in particular at least 70%, more preferably at least 80%, in particular at least 90% of the polyaryletherketone component. The remaining 10% to 50% by weight may consist of other polymers belonging to the PAEK family, for example polymers consisting of repeat units (III).

[0116] According to a particular embodiment, the composition comprises a single type of PAEK.

[0117] A thermoplastic polymer that provides ductility to the composition The thermoplastic polymer that gives the composition its ductility, i.e. the "flexible thermoplastic polymer", is not polyaryletherketone. Its modulus of elasticity is half that of polyaryletherketone.

[0118] According to a preferred embodiment, the elastic modulus of the flexible thermoplastic polymer may be less than or equal to 1.5 GPa. The low value of the elastic modulus is not limited other than that imposed by the very chemical nature of the thermoplastic polymer used. For thermoplastic polymers currently available on the market, the elastic modulus value is generally greater than or equal to 10 MPa.

[0119] According to certain embodiments, the flexible thermoplastic polymer may have a modulus of elasticity of 1 GPa or less, or even 750 MPa or less.

[0120] According to certain embodiments, the flexible thermoplastic polymer may have a modulus of elasticity of 50 MPa or more, or even 250 MPa or less.

[0121] According to certain embodiments, the flexible thermoplastic polymer may have a modulus of elasticity between 50 MPa and 1000 MPa, or between 250 MPa and 750 MPa.

[0122] According to a particular embodiment, the flexible thermoplastic polymer may be selected from the list consisting of linear polyenes, polysiloxanes, polysiloxane block copolymers, fluoroelastomers comprising at least one repeat unit derived from tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride and chlorotrifluoroethylene, and mixtures thereof.

[0123] According to a particular embodiment, said at least one flexible thermoplastic polymer may represent from 5% to 45% by weight relative to the total weight of said flexible thermoplastic polymer and polyaryletherketone of the composition.

[0124] The at least one flexible thermoplastic polymer may in particular represent from 5% to 10%, or from 10% to 15%, or from 15% to 20%, or from 20% to 25%, or from 25% to 30%, or from 30% to 35%, or from 35% to 40%, or from 40% to 45% by weight relative to the total weight of the flexible thermoplastic polymer and the polyaryletherketone of the composition.

[0125] According to an advantageous embodiment, said at least one thermoplastic polymer may represent between 7% and 25% by weight relative to the total weight of said flexible thermoplastic polymer and polyaryletherketone of the composition.

[0126] It is known to those skilled in the art that below a certain proportion of flexible thermoplastic polymer, said polymer contributes less to the ductility of the composition. Moreover, above a certain proportion of flexible thermoplastic polymer, the composition tends to lose the excellent heat and / or chemical resistance properties imparted by the PAEK. Furthermore, problems of interpolymer adhesion (delamination) may appear due to insufficient compatibility between the PAEK and the flexible thermoplastic polymer. Thus, the skilled artisan will be led to use, in a manner known per se, a greater or lesser proportion of flexible thermoplastic polymer, taking into account the expected effects and the phenomenon of compatibility.

[0127] The viscosity of the polyaryletherketone at 380° C. and 1 Hz and the viscosity of the flexible thermoplastic polymer are sufficiently close to facilitate dispersion of the flexible thermoplastic polymer in the polyaryletherketone matrix.

[0128] According to a particular embodiment, the maximum viscosity ratio between the polyaryletherketone and the flexible thermoplastic polymer is between 0.3 and 3. Preferentially, this ratio is greater than or equal to 0.5. It may in particular be greater than or equal to 0.7.

[0129] Preferentially, this ratio is less than or equal to 2. It may in particular be less than or equal to 1.5.

[0130] According to a particular embodiment, the flexible thermoplastic polymer may be a linear polyene, preferentially poly(3-methyloctenylene), poly(3-methyldecenylene) or a polyene of the formula

[0131] [ka]

[0132] Here, n is an integer from 3 to 10. In one embodiment, the repeat unit is selected from the list consisting of copolymers consisting essentially of or consisting of repeat units having the repeat units:

[0133] The linear polyene may in particular be chosen from the list consisting of polypentenylene, polyhexenylene, polyheptenylene, polyoctenylene, polynonenylene, polydecenylene, polyundecenylene, polydodecenylene, or mixtures thereof. According to a particular embodiment, the linear polyene is polyoctenylene.

[0134] The linear polyene may represent 5% to 45% by weight, relative to the total weight of said flexible thermoplastic polymer and polyaryletherketone of the composition. The linear polyene may in particular represent up to 25% by weight, preferentially up to 15% by weight, relative to the total weight of said flexible thermoplastic polymer and polyaryletherketone of the composition. According to an embodiment in which the linear polyene is the only flexible thermoplastic polymer, it may in particular represent 5% to 15% by weight, relative to the total weight of said flexible thermoplastic polymer and polyaryletherketone of the composition.

[0135] According to certain embodiments, the flexible thermoplastic polymer may be a fluoroelastomer comprising at least one repeat unit derived from tetrafluoroethylene (TFE), hexafluoropropylene (HFP), vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE).

[0136] Preferentially, the fluoroelastomer may be a copolymer consisting essentially of, or consisting of, repeating units derived from HFP and VDF or otherwise, or a copolymer consisting essentially of, or consisting of, repeating units derived from TFE and at least one repeating unit derived from propylene, HFP, or another perfluoro(alkyl vinyl ether).

[0137] In particular, fluoroelastomers are made up of repeating units derived from TFE and the chemical formula CF2=CF-R (VII) and repeat units derived from monomers of the formula:1~5 Preferably, the compound of formula (VII) is selected from the group consisting of hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether) and perfluoro(propyl vinyl ether). More preferably, the compound of formula (VII) is selected from the group consisting of hexafluoropropylene and perfluoro(propyl vinyl ether).

[0138] According to a particular preferred embodiment, the repeating units derived from TFE can account for 80 mol % to 99.5 mol % based on the total number of moles of the units derived from TFE and the monomer of formula (VII). The repeating units derived from TFE can in particular account for 85 mol % or more, or 87 mol % or more, or 93 mol % or more based on the total number of moles of the units derived from TFE and the monomer of formula (VII).

[0139] According to a particular embodiment, the flexible thermoplastic polymer is a copolymer consisting essentially of or consisting of repeat units derived from TFE and HFP, with 7 mol% to 15 mol% TFE relative to the total number of moles of units derived from TFE and HFP. Examples of such commercially available fluoropolymers include the NEOFLON™ FEP series of polymers sold by DAIKIN, or the Teflon™ FEP series of polymers sold by Dupont, or the 3M™ Dyneon™ fluoroplastic FEP series of polymers sold by 3M.

[0140] The fluoroelastomer may represent from 10% to 40% by weight, and preferentially from 15% to 25% by weight, relative to the total weight of said flexible thermoplastic polymer and of the polyaryletherketone of the composition.

[0141] According to certain embodiments, the thermoplastic polymer may be a block copolymer including polysiloxane blocks.

[0142] Polysiloxane block is C1-C 12 , preferably with C1-C6, especially C1-C4 alkyl groups, and / or phenyl groups. Preferably, the alkyl groups are methyl groups. Preferably, the polysiloxane units present in the block copolymer comprising the polysiloxane block are poly(dimethylsiloxane) (PDMS) units.

[0143] The alkyl or phenyl group of the polysiloxane block may also be substituted with one or more functional groups, such as epoxy, alkoxy, in particular methoxy, amine, ketone, thioether, halogen, nitrile, nitro, sulfone, phosphoryl, imino or thioester. These functional groups may be located at the ends of the chains of block copolymers that contain the polysiloxane block. However, preferably, the polysiloxane block does not contain any functional groups. Furthermore, the alkyl or phenyl group of the polysiloxane block may be substituted with one or more carbocyclic, aryl, heteroaryl, alkyl, alkenyl, bicyclo or tricyclo groups.

[0144] Block copolymers containing polysiloxane blocks further contain blocks of units other than polysiloxane. They may in particular be polyetherimide, poly(aryletherketone), poly(arylethersulfone), poly(phenylene sulfide), poly(arylamideimide), poly(phenylene), poly(benzimidazole) and / or polycarbonate blocks. Preferably, block copolymers containing polysiloxane blocks also contain polyaryletherketone or polyetherimide blocks. The advantage of these blocks is that they are highly compatible with the polyaryletherketones of the composition, allowing the incorporation of large amounts of flexible thermoplastic polymers into the composition.

[0145] The polyaryletherketone blocks may be selected from the same list as the polyaryletherketones used as constituents of the composition. According to an advantageous embodiment, the polyaryletherketone blocks may have the same chemical composition as the polyaryletherketones used as constituents of the composition.

[0146] Preferentially, the polyetherimide block has the formula

[0147] [ka]

[0148] comprising, consisting essentially of, or consisting of a repeat unit having the formula: where A represents: -O- or a group of formula -OZO-, where the -O- and -OZO- divalent groups are in the 3,3', 3,4' or 4,4' positions of the benzene radical to which they are attached; and Here, Z is

[0149] [ka]

[0150] [ka]

[0151] You can choose from a list of Here, Q is -O-, -S-, -C(O)-, -SO2-, -SO-, -C y H 2y - (y is an integer from 0 to 20) and halogenated derivatives thereof; Here, B represents an aromatic hydrocarbon group having 6 to 20 carbon atoms or a halogenated derivative thereof, a linear or branched alkylene chain having 2 to 20 carbon atoms, a cycloalkylene having 3 to 20 carbon atoms, or a divalent group of formula (XIII).

[0152] The block copolymer comprising polysiloxane blocks may represent a siloxane content of 10% to 70% by weight, preferentially 15% to 60%, more preferably 20% to 50% by weight relative to the weight of the copolymer. The block copolymer comprising polysiloxane blocks may represent 5% to 20% by weight, preferentially 7% to 15% by weight relative to the total weight of said at least one thermoplastic and at least one polyaryletherketone of the composition.

[0153] Such block copolymers containing polysiloxane blocks are commercially available: thus, Sabic sells copolymers containing PEI-PDMS blocks under the name Siltem®, and Idemitsu Kosan sells polycarbonate-PDMS copolymers under the name Tarflon® Neo.

[0154] According to a particular embodiment, the flexible thermoplastic polymer may be a polysiloxane. 12 , preferably C1-C6, very particularly C1-C4 alkyl groups, and / or phenyl groups. Preferably, the alkyl groups are methyl groups. The alkyl or phenyl groups of the polysiloxane may be substituted with one or more functional groups, such as epoxy, alkoxy, especially methoxy, amine, ketone, thioether, halogen, nitrile, nitro, sulfone, phosphoryl, imino or thioester.

[0155] Nevertheless, preferably, the polysiloxane does not contain any functional groups. Furthermore, the alkyl or phenyl groups of the polysiloxane may be substituted with one or more carbocyclic, aryl, heteroaryl, alkyl, alkenyl, bicyclic or tricyclic groups.

[0156] Preferably, the polysiloxane may be poly(dimethylsiloxane) (PDMS).

[0157] The polysiloxane may represent 1% to 25% by weight, based on the total weight of said flexible thermoplastic polymer and polyaryletherketone of the composition.

[0158] According to a particular embodiment, the polysiloxane may represent 2% or more by weight, or 3% or more, or 4% or more, or 5% or more by weight, relative to the total weight of said flexible thermoplastic polymer and polyaryletherketone of the composition.Since the polysiloxane has very low compatibility with the polyaryletherketone, it may represent 20% or less by weight, preferentially 15% or less, more preferably 13% or less by weight, relative to the total weight of said flexible thermoplastic polymer and polyaryletherketone of the composition.

[0159] According to a particular embodiment, said at least one flexible thermoplastic polymer of the composition is a mixture of a block copolymer comprising a polysiloxane block, in particular a block copolymer further comprising a polyaryletherketone or a polyetherimide block, and a polysiloxane.

[0160] Other optional components of the composition According to preferred embodiments, the composition may comprise, relative to the total mass of polyaryletherketone and flexible thermoplastic polymer, at least 85%, or at least 90%, or at least 92.5%, or at least 95%, or at least 97.5%, or at least 98%, or at least 98.5%, or at least 99%, or at least 99.5%, or 100%.

[0161] The composition is preferentially free of reinforcing fillers, especially fibres, as indeed reinforcing fillers generally have the effect of reducing the ductility of the material.

[0162] In addition to the polyaryletherketone and the flexible thermoplastic polymer, the composition may also contain other polymers that are miscible with the polyaryletherketone and are therefore incorporated into the matrix in which the flexible thermoplastic polymer is dispersed, in other words, without forming nodules in addition to those of the flexible thermoplastic polymer.

[0163] The composition may also optionally contain small amounts of functional additives, in particular less than 5% by weight relative to the weight of the composition, examples of which may be mentioned are antioxidants, molten and / or solid state stabilizers, conductive and / or antistatic agents, flame retardants, dyes, and reactive agents such as alkali carbonates.

[0164] Thus, according to certain embodiments, the composition may consist of a polyaryletherketone, a flexible thermoplastic polymer, optionally a polymer other than the polyaryletherketone and the flexible thermoplastic polymer, which is miscible with the polyaryletherketone, and optionally one or more functional additives.

[0165] According to a particular embodiment, the composition may consist of a polyaryletherketone and a flexible thermoplastic polymer, in particular of a single polyaryletherketone and a single flexible thermoplastic polymer.

[0166] powder Powders according to the present invention comprise particles of the compositions, several embodiments of which are described above.

[0167] Preferably, the powder does not contain other particles of different chemical composition.The powder therefore preferentially consists of the above-mentioned composition comprising at least one polyaryletherketone and at least one flexible thermoplastic polymer.This has the advantage that the recycling of the powder can be more easily carried out, for example in embodiments in which the powder is used in a method for constructing an object by laser sintering.

[0168] In a particular embodiment, the particles may have a volume-weighted particle size distribution with a median diameter d50 in the range of 40 to 140 micrometers, as measured by laser diffraction according to the ISO13320:2009 standard. Preferentially, the median diameter d50 may be 50 to 120 micrometers. More preferably, the median diameter d50 may be 60 to 110 micrometers.

[0169] According to certain embodiments, d10 may be 15 micrometers or more, or 30 micrometers or more.

[0170] According to particular embodiments, d90 may be less than or equal to 300, preferentially less than or equal to 240 micrometers. According to particular embodiments, the value of d90 may be less than or equal to 180 micrometers.

[0171] According to an advantageous embodiment, in particular for the application of the powder in a layer-by-layer construction method of a three-dimensional object by electromagnetic radiation mediated sintering, the particle size distribution of the powder is: d10≧15μm, 60μm≦d50≦110μm, d90≦240μm etc.

[0172] According to certain embodiments, in particular for the application of the powder in a method for layer-by-layer construction of a three-dimensional object by electromagnetic radiation mediated sintering, the particle size distribution of the powder is: d10≧30μm, 80μm≦d50≦100μm, d90≦180μm etc.

[0173] According to a particular embodiment, the powder does not contain a flow agent. Advantageously, even in the absence of a flow agent, it may have a powder flowability of less than or equal to 10 seconds, preferentially less than or equal to 7 seconds, and very preferably less than or equal to 5 seconds.

[0174] According to a particular embodiment, the powder has a density of 500 kg / m 3Such powders used in the process of making an object have a density approaching the density desired for the object being made, which allows less air from the powder to have to be evacuated during the process of making the object, and therefore objects with low porosity can be more easily obtained.

[0175] According to a particular embodiment, the powder is an amorphous powder.

[0176] According to a particular embodiment, the powder is at least partially crystalline: it may have a crystallinity, in particular as measured by X-ray diffraction, of 10% or more by mass, preferentially 15% or more, more preferably 18% or more, relative to the total mass of polymer in the composition.

[0177] Use of powder Powders according to the present invention can be used in a number of applications, including the non-exhaustive list below.

[0178] Layer-by-layer building methods of objects by sintering mediated by electromagnetic radiation, in particular infrared or laser radiation, are well known to those skilled in the art. With reference to FIG. 1, a laser sintering apparatus 1 comprises a sintering chamber 10 in which a supply tank 40 containing the powder to be sintered, a horizontal plate 30 for supporting the three-dimensional object 80 being built, and a laser 20 are arranged. The powder is taken from the supply tank 40 and deposited on the horizontal plate 30 to form a thin layer 50 of powder constituting the three-dimensional object 80 being built. A forming roller / doctor blade (not shown) ensures good uniformity of the powder layer 50. The powder layer 50 being built is heated by infrared radiation 100 to reach a substantially uniform temperature equal to a predetermined building temperature Tc. In conventional building methods for sintering PAEK-based powders, Tc is generally about 20° C. lower than the melting temperature of the powder measured by DSC during the first heating with a temperature ramp equal to 20° C. / min. In some cases, Tc can be even lower. The energy required to sinter the powder particles at various points of the powder bed 50 is then provided by laser radiation 200 from a laser 20 movable in a plane (xy) corresponding to the shape of the object. The molten powder resolidifies to form a sintered portion 55, while the remaining part of the layer 50 remains in the form of green powder 56. In some cases, it may be necessary to perform the laser radiation 200 several times. The horizontal plate 30 is then lowered along the axis (z) a distance corresponding to the thickness of one layer of powder and a new layer is deposited. The laser 20 provides the energy required to sinter the powder particles in the shape corresponding to this new slice of the object, and so on. This procedure is repeated until the entire object 80 is produced. Once the object 80 is completed, it is removed from the horizontal plate 30 and the green powder 56 is sorted, if necessary, before being returned to the supply tank 40 and provided as recycled powder.

[0179] The powders according to the invention can also be used in a method for coating surfaces, in particular metal surfaces. To obtain a coating on a metal part, different processes can be used. Fluidized bed immersion is a method in which the metal part is heated and then immersed in a fluidized powder bed. Electrostatic powder coating (charged powder sprinkled on a grounded metal part) is also possible, in which case a heat treatment is carried out to produce the coating. An alternative is to powder coat a preheated part, in which case the heat treatment can be removed after powder coating. Finally, flame powder coating is also possible, in which the powder is molten sprayed onto an optionally preheated metal part.

[0180] The powder according to the invention can also be used in powder compaction processes. These methods are generally used to manufacture thick parts. In these methods, the powder is first loaded into a mold, then compressed and finally melted to produce the part. Finally, an appropriate cooling is performed, often quite slowly, to limit the presence of internal stresses in the part.

[0181] The objects obtained by these methods have properties that were not previously obtainable due to the impossibility of producing a powder comprising at least one flexible thermoplastic polymer dispersed in a matrix of PAEK.

[0182] An object obtained by one of the methods described above, preferentially by a method for layer-by-layer construction of an object by electromagnetic radiation mediated sintering, may have an elastic modulus strictly less than 4 GPa, in particular when measured on a 1BA test specimen at 23° C. according to the ISO 527-1:2019 standard.

[0183] The object obtained by one of the above mentioned methods, preferentially by the layer-by-layer construction method of the object by electromagnetic radiation mediated sintering, has a sintering power of 5 kJ / m for a notched bar of type A according to the ISO 179:2010 standard. 2 Above 6kJ / m 2 Above 7kJ / m 2 Above 8kJ / m2 More than 9 kJ / m, most preferably 2 It can have a Charpy impact strength of at least 1000 MPa.

[0184] Powder manufacturing method The method for producing a powder according to the present invention comprises the steps of: - providing a molten composition in a molten state; - atomizing the composition in a molten state to form droplets of the molten composition; - cooling the droplets of the molten composition to form solid particles; and - optionally one or more heat treatment steps, Includes.

[0185] The processes of melt spraying and cooling are known per se for pure polymer compositions. They make it possible to obtain micropowders of said polymers. Such a process is described, for example, in EP 0 945 173.

[0186] With reference to FIG. 2, the melt spraying device 2 comprises means 3 for feeding the molten composition to a spray nozzle 4 arranged at the top of the device. The spray nozzle 4 sprays the molten composition in the form of a fine jet which breaks up into minute droplets 5 as it descends. The molten droplets cool and solidify as they fall. To reduce the height of the droplets and / or to accelerate the cooling, a cryo-gas, for example liquid nitrogen or liquid carbon dioxide, can be blown in gaseous form into the device by a feeder 6 arranged at the side wall of the device. A fine solid powder 7 is thus obtained at the bottom of the device.

[0187] The mixture in the molten state can be prepared by any method known in the art.

[0188] The composition can be provided, for example, in the form of PAEK granules in which the flexible thermoplastic polymer is dispersed. Alternatively, each component can be provided separately and the composition in the molten state can be produced in situ using known melt mixing equipment suitable for preparing thermoplastics. Suitable melt mixing equipment are, for example, kneaders, Banbury mixers, single screw extruders and twin screw extruders.

[0189] The powders obtained by the atomization process are generally amorphous or semi-amorphous because the droplets of the molten composition cool very rapidly.

[0190] The amorphous powder can, if appropriate, undergo one or more heat treatment steps. One (first) heat treatment step can be carried out at or above the glass transition temperature Tg and below the melting temperature of the polyaryletherketone of the composition to cause crystallization of the composition. Optionally, if necessary, a second heat treatment can be carried out to homogenize the crystalline phase of the composition. Such heat-treated powders are particularly suitable for use in layer-by-layer construction methods of objects by electromagnetic radiation-mediated sintering.

[0191] For example, in embodiments where the polyaryletherketone of the composition is a PEKK consisting essentially of isophthalic and terephthalic repeat units and the T / I molar ratio is 45:55 to 75:25, particularly where the T / I ratio is about 60:40, the heat treatment may be carried out at a temperature between 160°C and 300°C, preferentially between 180°C and 290°C, more preferably between 190°C and 250°C, for a time sufficient to obtain the desired degree of crystallinity.

[0192] It is also known that PEKK crystallizes in two crystalline forms, called "form I" and "form II". In such cases, after the first heat treatment, a second heat treatment can be advantageously carried out so as to obtain a powder essentially comprising PEKK crystals of form I. This method is known per se and has already been described in application WO 2012 / 047613. In the case of a powder consisting of a composition comprising PEKK having a T / I ratio of about 60:40, the temperature of the second heat treatment can be in particular between 230°C and 300°C, preferentially between 260°C and 295°C. The temperature of the second heat treatment can in particular be between 275°C and 290°C.

[0193] The temperature of the second heat treatment is generally higher than that of the first heat treatment. Thus, continuing with the example of a powder consisting of a composition comprising PEKK having a T / I molar ratio of about 60:40, in particular, the first heat treatment can be carried out at a temperature of 160° C. to 250° C. and the second heat treatment at a temperature of 260° C. to 300° C. EXAMPLES

[0194] raw materials The following commercially available products were used in the examples: - 6000 grade KEPSTAN®, sold by ARKEMA, is a polyetherketoneketone with a T / I molar ratio of 60 / 40. This PEKK has a viscosity of 900 Pa·s at 380°C and 1 Hz. Five 1BA specimens were prepared by injection molding on a Battenfeld press with the following parameters: feed 330°C; nozzle 345°C; mold 80°C. At these molding conditions, the specimens were obtained in a substantially amorphous form. The tensile modulus was measured to be 2.9 GPa at 23°C and a crosshead speed of 1 mm / min according to the ISO 527-1:2019 standard.

[0195] For comparison, the tensile modulus of a specimen obtained by laser sintering with a crystallinity of 20% was measured to be 4 GPa at 23° C. and a crosshead speed of 1 mm / min (see Table 2, composition #3c).

[0196] - NEOFLON™ NF101, sold by Daikin, is a copolymer consisting essentially of repeating units of TFE and HFP (FEP). This FEP copolymer has a viscosity of 1200 Pa·s at 380°C and 1 Hz. The supplier indicates that the NEOFLON™ FEP family, which includes NEOFLON™ NF101, has a tensile modulus of 440-540 MPa (ASTM D638).

[0197] - SILTEM® 1500, sold by Sabic, is a polyetherimide-polydimethylsiloxane (PEI / PDMS) block copolymer. SILTEM® 1500 has a mass fraction of polydimethylsiloxane of 40% relative to the total mass of the polymer and a viscosity of 800 Pa·s at 380°C and 1 Hz. The supplier indicates that SILTEM® 1500 has a tensile modulus of 590 MPa at a crosshead speed of 1 mm / min (ISO 527).

[0198] PEKK is mixed with various flexible thermoplastic polymers to produce ZSK Mc 18 The mixtures were fed into the main hopper of a twin-screw extruder and extruded at a temperature of 320° C. The screw speed was 250 rpm for the PEKK and PEI / PDMS block copolymer mixtures and 320 rpm for the PEKK and FEP mixtures.

[0199] The granules thus obtained were sprayed using an apparatus as shown in FIG. 2 to obtain a solid powder.

[0200] Two successive heat treatments were performed: first the powder was treated at 185°C for 6 h and then at 270°C for 3 h.

[0201] For comparison with the powders formulated in the examples according to the invention, a control powder #3c was also prepared, which consisted of PEKK and was produced by a conventional method of grinding flakes of crystalline polymer, followed by densification and heat treatment steps.

[0202] PEKK flakes with a viscosity of about 900 Pa·s at 380 °C and 1 Hz were synthesized by an electrophilic method. They were first finely ground using an Alpine Hosokawa AFG200 air jet mill at a temperature of 23 °C to obtain powders with particle size distributions of d10 = 30 microns, d50 = 69 microns, and d90 = 132 microns.

[0203] This powder was called "non-densified" and was then subjected to a thermomechanical treatment in a Henschel Rapid Mixer with a blade tip speed of about 43 m / s for 60 min. Densified powder was obtained. The tapping density of the densified powder was 440 kg / m 3 Finally, the densified powder was heat treated at 275°C for 4 hours.

[0204] The table below shows the properties of powders #1 to #3c.

[0205] [Table 1]

[0206] 1BA test piece and dimensions: 80 x 10 x 4 mm 3 The bars were printed in the xy plane using a P810 printer sold by EOS. The printing temperature was 285°C and the laser energy was 29 mJ / mm 2 was set to.

[0207] 1BA specimens were used to determine the tensile modulus of objects produced by laser sintering of powders at 23 °C and a crosshead speed of 1 mm / min.

[0208] The bars, which had been pre-V notched and allowed to sit for 24 hours, were used to determine the Charpy impact strength.

[0209] The table below shows the results of these tests.

[0210] [Table 2]

[0211] Thus, powders #1 and #2 according to the invention, obtained by PEKK-based laser sintering, made it possible to produce objects with a lower modulus of elasticity and higher impact strength than was possible with the powder according to the prior art (powder #3c).

[0212] Another comparative example: production of powder from PEKK granules obtained by compounding. Approximately 2 mm PEKK granules were extruded. The granules were heat treated at 180°C for 9 hours to increase the crystallinity and make them more brittle during the milling process. Finally, the mill was further milled in a Mikropul 2DH® cryogenic hammer mill equipped with a 500 micron round hole screen and cooled with liquid nitrogen. The resulting powder has a d50 of 500 microns.

[0213] Thus, for PEKK granules obtained by compounding, it is generally not possible to obtain, by grinding, a powder with a d50 strictly below 500 microns, even if said granules are pre-crystallized under cryogenic conditions.

[0214] Milling under similar conditions of granules obtained by compounding compositions consisting of PEKK and flexible thermoplastic polymers, such as the granules used to prepare powders #1 and #2, would be much more difficult to carry out and would not be possible to obtain powders with a d50 strictly below 500 microns. [Explanation of symbols]

[0215] 1 Laser sintering equipment 2. Melt spray equipment 3. Means for supplying the composition in a molten state 4 Spray nozzle 5 Micro droplets 6 Feeding device 7 Solid fine powder 10 Sintering chamber 20. Laser 30 Horizontal Plate 40 Supply Tank 50 powder bed 55 Sintering section 56 Unsintered Powder 80 Three-dimensional objects 100 Infrared 200 Laser Radiation

Claims

1. 1. A powder comprising particles consisting of a composition comprising at least one polyaryletherketone and at least one flexible thermoplastic polymer that is not a polyaryletherketone, wherein the particles have a volume-weighted particle size distribution with a median diameter d50 of less than 500 μm, as measured by laser diffraction according to the ISO 13320:2009 standard; the at least one flexible thermoplastic polymer has a modulus of elasticity at least two times lower than the at least one polyaryletherketone, measured according to the ISO 527-2:2012 standard at 23°C on 1BA specimens obtained by injection molding at a crosshead speed of 1 mm / min, the polyaryletherketone forming a matrix in which the flexible thermoplastic polymer is dispersed, powder.

2. 2. The powder of claim 1, wherein the flexible thermoplastic polymer has an elastic modulus of less than or equal to 1.5 GPa, measured on 1 BA specimens at 23°C according to the ISO 527-2:2012 standard.

3. 3. Powder according to claim 1 or 2, wherein the at least one flexible thermoplastic polymer is selected from the list consisting of linear polyenes, polysiloxanes, polysiloxane block copolymers, fluoroelastomers comprising at least one repeating unit derived from tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride and chlorotrifluoroethylene, and mixtures of these polymers.

4. the at least one flexible thermoplastic polymer Repeating units derived from tetrafluoroethylene and the chemical formula CF 2 =C(F)(R) (Wherein R is -CF 3 group or -ORf group, where Rf is C 1～5 perfluoroalkyl) 4. The powder according to claim 3, comprising repeating units derived from a monomer of the formula (I), wherein the repeating units account for a molar ratio of 95% to 100% relative to the total number of moles of repeating units in the polymer.

5. 4. The powder of claim 3, wherein the at least one flexible thermoplastic polymer comprises a block copolymer comprising polysiloxane blocks.

6. 2. The powder of claim 1, wherein the at least one flexible thermoplastic polymer represents from 5% to 40% by weight, relative to the total weight of the at least one flexible thermoplastic polymer and the at least one polyaryletherketone of the composition.

7. 2. The powder of claim 1, wherein the combined weight of the polyaryletherketone and flexible thermoplastic polymer accounts for at least 85%, or at least 90%, or at least 92.5%, or at least 95%, or at least 97.5%, or at least 98%, or at least 98.5%, or at least 99%, or at least 99.5%, or 100%, of the total weight of the composition.

8. 10. The powder of claim 1, wherein the composition consists of a polyaryletherketone, a flexible thermoplastic polymer, optionally a polymer other than the polyaryletherketone and the flexible thermoplastic polymer, which other polymer is miscible with the at least one polyaryletherketone, and optionally one or more functional additives.

9. 10. The powder of claim 1, wherein the particles have a volume-weighted particle size distribution with a median diameter d50 in the range of 40 to 140 micrometers as measured by laser diffraction according to the ISO 13320:2009 standard.

10. 500 kg / m when measured according to ISO1068:1975 standard 3 The powder of claim 1 having a tapping density of at least 1000 kJ / cm2.

11. 10. The powder of claim 1, having a powder flowability of 10 seconds or less when measured according to method "A" of the ISO 6186:1998 standard without a flow agent.

12. 10. The powder of claim 1, which is amorphous.

13. 10. The powder of claim 1, which is crystalline.

14. 10. The powder of claim 1, wherein the at least one polyaryletherketone is a polyetherketoneketone.

15. The polyetherketoneketone comprising terephthalic units and optionally isophthalic units, Terephthalic units (T) 【Chemical 1】 having the chemical formula Isophthalic units (I) 【Chemistry 2】 having the chemical formula 15. The powder of claim 14, wherein the molar ratio of T:I is in the range of 0:100 to 85:15, and the terephthalic units and optionally isophthalic units account for a molar ratio of 95% to 100% relative to the total number of moles of repeat units in the polymer.

16. A method for producing the powder according to claim 1, - providing a composition in a molten state comprising said at least one flexible thermoplastic polymer dispersed in a polymer matrix comprising said at least one polyaryletherketone; - atomizing said composition in a molten state to form droplets of the molten composition; - cooling the droplets of the molten composition to form solid particles; and - Optionally one or more heat treatment steps A manufacturing method comprising:

17. 10. Use of the powder according to claim 1 in a method for layer-by-layer building of objects by electromagnetic radiation mediated sintering, in a powder coating, powder compression molding or powder compression-transfer molding method.

18. 18. An object obtainable by one of the methods according to claim 17, having an elastic modulus of less than 4 GPa when measured on a 1 BA test specimen at 23°C according to the ISO 527-1:2019 standard.

19. An object obtained by one of the methods according to claim 17, 5kJ / m for Type A notched bars according to ISO179:2010 standard 2 Charpy impact strength of more than object.

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