Thermoplastic polyester for manufacturing 3D printed objects

Abstract

The present invention relates to the use of a thermoplastic polyester for producing a 3D printed object, the polyester comprising at least one 1.4:3.6-dianhydrohexitol unit (A), at least one ethylene glycol unit (B), and at least one terephthalic acid unit (C), wherein the ratio (A) / [(A)+(B)] is at least 0.01 and at most 0.60, the polyester containing no cycloaliphatic diol units or comprising cycloaliphatic diol units in a molar amount of less than 5% relative to the total number of monomer units in the polyester, and having a reduced viscosity in solution (35°C; orthochlorophenol; 5 g / L polyester) of more than 40 mL / g.

Description

[Technical Field]

[0001] The present invention relates to the field of 3D printing, and in particular to the use of thermoplastic polyesters for the production of 3D printed objects, which thermoplastic polyesters have properties that make them particularly interesting for this application. [Background technology]

[0002] The field of 3D printing has grown rapidly in recent years, and it is now possible to produce 3D printed objects in a number of materials, such as plastic, wax, metal, plaster of Paris, and even ceramic.

[0003] Although there is a wide variety of materials available, the selection of available compounds within each material can be limited.

[0004] With regard to 3D printed objects that are manufactured using plastic materials, only a few polymers can be used, especially due to the filament spools used in certain 3D printing techniques.

[0005] Currently, polymers such as ABS (acrylonitrile-butadiene-styrene) and PLA (polylactic acid) play a major role alongside polyamides and photoresins or photopolymers.

[0006] ABS is an amorphous polymer whose Tg varies between 100 and 115°C depending on its composition, which limits its molding. In fact, its use requires relatively high process temperatures of 220-240°C, especially bed temperatures of 80-110°C, which require particularly suitable equipment. In addition, the use of ABS to obtain solid objects always results in very significant shrinkage, which leads to visible dents and cracks in the final object.

[0007] PLA (alone or optionally mixed, typically with polyhydroxyalkanoates) is less demanding in terms of the temperature required, and one of its main features is its low shrinkage during 3D printing, which is why the use of a heated plate is not necessary during 3D printing by the FDM (Fused Deposition Modeling) technique. However, its main limitation is the low glass transition temperature of the mixture, around 60°C.

[0008] Certain thermoplastic aromatic polyesters have thermal properties that allow them to be used directly in the production of materials. They contain units of aliphatic diols and aromatic dicarboxylic acids. Among these aromatic polyesters, mention may be made of polyethylene terephthalate (PET), a polyester containing units of ethylene glycol and terephthalic acid.

[0009] If the SLS (Selective Laser Sintering) technique is used, the number of available polymers is also very limited. The most suitable polymers are semi-crystalline, since sintering results from a melting / recrystallization process and makes it possible to obtain a very good cohesion of the material. Some materials such as polyamides (PA12, PA11), as well as thermoplastic polyurethanes (TPU), polyetherketones (PEK), polyetheretherketones (PEEK), and polyetherblockamides (PEBA) are the most commonly found.

[0010] technical issues However, for certain applications or under certain conditions, it is necessary to improve some properties, especially impact resistance or heat resistance. Therefore, glycol-modified PET (PETg) has been developed. These are generally polyesters containing cyclohexanedimethanol (CHDM) units in addition to ethylene glycol and terephthalic acid units. The introduction of this CHDM diol into PET makes it possible to tailor its properties to the intended application, for example, to improve its impact resistance or its optical properties, especially when PETg is amorphous.

[0011] Other modified polyesters have also been developed by incorporating 1,4:3,6-dianhydrohexitol units, particularly isosorbide (PEIT), into polyesters. These modified polyesters have higher glass transition temperatures than unmodified PET or PETg containing CHDM. Furthermore, 1,4:3,6-dianhydrohexitol has the advantage that it can be obtained from renewable resources such as starch.

[0012] It is known from the prior art to use polyesters with reduced crystallinity in order to improve their impact resistance, and the aim is therefore to obtain a polymer in which the crystallinity has been removed by adding a comonomer, in this case 1,4-cyclohexanedimethanol.

[0013] With regard to isosorbide-based polyesters, reference may be made to US Patent Application Publication No. 2012 / 0177854, which discloses impact-improved polyesters comprising terephthalic acid units and diol units comprising 1 to 60 mol % isosorbide and 5 to 99 % 1,4-cyclohexanedimethanol.

[0014] The use of copolyesters with improved thermal properties and necessarily containing cycloaliphatic diols such as CHDM, isosorbide, and terephthalic acid for 3D printing applications is disclosed in WO 2018020192. Such copolyesters are free of or contain residual amounts of ethylene glycol.

[0015] WO2018212596 discloses a blend of polyesters used to produce 3D printed filaments. The blend consists of a polyester A containing at least isosorbide and terephthalic acid and a polyester B containing a diol other than terephthalic acid and isosorbide. To produce a 3D object using such a blend, an additional step of homogenizing the two polyesters is required.

[0016] Thanks to the Applicant, it has therefore been found that this demand for alternative plastic raw materials for use in 3D printing can be met, contrary to all expectations, by thermoplastic polyesters based on 1,4:3,6-dianhydrohexitol, and in particular isosorbide, which have no or very few cycloaliphatic diol units, in particular CHDM, whereas until now the latter were known to be essential in order to obtain polymers with good thermal and optical properties, with reduced or even eliminated crystallinity. Summary of the Invention

[0017] Therefore, the present invention One aspect The present invention relates to the use of a thermoplastic polyester for producing a 3D printed object, the polyester comprising: at least one 1.4:3.6-dianhydrohexitol unit (A), at least one ethylene glycol unit (B), - at least one terephthalic acid unit (C), the molar ratio (A) / [(A)+(B)] is at least 0.01 and at most 0.60; The polyester does not contain alicyclic diol units or contains alicyclic diol units in a molar amount of less than 5% relative to the total amount of monomer units in the polyester, and has a reduced viscosity in a solution (35°C; orthochlorophenol; 5 g / L polyester) of more than 40 mL / g.

[0018] The present invention One aspect relates to 3D printed objects comprising the thermoplastic polyesters disclosed above.

[0019] lastly, One aspect of the present invention is a method for producing a 3D printed object from the thermoplastic polyester disclosed above, the method comprising: - preparing a thermoplastic polyester comprising at least one 1.4:3.6-dianhydrohexitol unit (A), at least one ethylene glycol unit (B) other than the 1.4:3.6-dianhydrohexitol unit (A), and at least one terephthalic acid unit (C), wherein the molar ratio (A) / [(A)+(B)] is at least 0.01 and at most 0.60, the polyester containing no cycloaliphatic diol units or a molar amount of cycloaliphatic diol units of less than 5% relative to the total monomer units in the polyester, and the reduced viscosity in solution (35°C; orthochlorophenol; 5 g / L polyester) of greater than 40 mL / g; - molding the thermoplastic polyester obtained in the previous step; - 3D printing an object from molded thermoplastic polyester; - recovering the 3D printed object.

[0020] The thermoplastic polyesters used according to the present invention offer excellent properties and allow for the production of 3D printed objects.

[0021] Polymer compositions incorporating such thermoplastic polyesters are particularly advantageous and have improved properties, and indeed their presence in the composition can provide additional properties and broaden the range of applications for other polymers.

[0022] The thermoplastic polyesters according to the invention therefore have very good properties, in particular optical and thermal properties, and are particularly suitable for use in the production of 3D printed objects, which production is not limited by the 3D printing method used. DETAILED DESCRIPTION OF THE INVENTION

[0023] Therefore, the present invention One aspect The present invention relates to the use of a thermoplastic polyester for producing a 3D printed object, the polyester comprising: at least one 1.4:3.6-dianhydrohexitol unit (A), at least one ethylene glycol unit (B), - at least one terephthalic acid unit (C), the molar ratio (A) / [(A)+(B)] is at least 0.01 and at most 0.60; The polyester does not contain alicyclic diol units or contains alicyclic diol units in a molar amount of less than 5% relative to the total amount of monomer units in the polyester, and has a reduced viscosity in a solution (35°C; orthochlorophenol; 5 g / L polyester) of more than 40 mL / g.

[0024] "(A) / [(A)+(B)] molar ratio" is intended to mean the molar ratio of 1.4:3.6-dianhydrohexitol units (A) / the sum of 1.4:3.6-dianhydrohexitol units (A) and ethylene glycol diol units (B).

[0025] The thermoplastic polyester contains no or a small amount of cycloaliphatic diol units.

[0026] "A small molar amount of cycloaliphatic diol units" is intended to mean in particular a molar amount of cycloaliphatic diol units of less than 5%, which, according to the invention, represents the ratio of the sum of the cycloaliphatic diol units (which may be identical or different) to the sum of the monomer units in the polyester.

[0027] The alicyclic diol is also called an aliphatic and cyclic diol. The alicyclic diol is most preferably 1,4-cyclohexanedimethanol. The alicyclic diol (B) may be in the cis or trans configuration, or may be a mixture of cis and trans configuration diols.

[0028] The polyester may contain no cycloaliphatic diol units or may contain cycloaliphatic diol units in a molar amount of less than 1% relative to the total of the monomer units in the polyester, and preferably the polyester does not contain cycloaliphatic diol units.

[0029] Thus, the molar amount of cycloaliphatic diol units, which may be selected from 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol or mixtures thereof, is advantageously less than 1%. Preferably, the polyester does not contain cycloaliphatic diol units, which may be selected from 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol or mixtures thereof. More preferentially, it does not contain 1,4-cyclohexanedimethanol.

[0030] Despite the small amount or absence of the cycloaliphatic diol used in the synthesis, i.e., 1,4-cyclohexanedimethanol, a thermoplastic polyester is obtained that surprisingly has a high reduced viscosity in solution and allows the amount of isosorbide incorporated to be controlled. Thus, depending on the isosorbide incorporation rate, amorphous or semi-crystalline copolyesters can be obtained, widening the range of properties available for 3D-printed objects obtained by different manufacturing methods, whether by filament printing or SLS.

[0031] Monomer (A) is a 1.4:3,6-dianhydrohexitol and can be isosorbide, isomannide, isoidide, or a mixture thereof. Preferably, the 1.4:3,6-dianhydrohexitol (A) is isosorbide.

[0032] Isosorbide, isomannide, and isoidide can be obtained by dehydration of sorbitol, mannitol, and iditol, respectively. Isosorbide is sold by the applicant under the trade name POLYSORB®.

[0033] The molar ratio of 1.4:3.6-dianhydrohexitol units (A) to the sum of 1.4:3.6-dianhydrohexitol units (A) and ethylene glycol diol units (B), i.e., (A) / [(A) + (B)], is at least 0.01 and at most 0.60. When the molar ratio (A) / [(A) + (B)] is less than 0.15, the thermoplastic polyester is semi-crystalline and is characterized by the presence of a crystalline phase resulting in X-ray diffraction lines and the presence of an endothermic melting peak in differential scanning calorimetry (DSC) analysis.

[0034] Conversely, when the molar ratio (A) / [(A)+(B)] is greater than 0.15, the thermoplastic polyester is amorphous, characterized by the absence of X-ray diffraction lines and by the absence of an endothermic melting peak in differential scanning calorimetry (DSC) analysis.

[0035] Thermoplastic polyesters that are particularly suitable for producing 3D printed objects are: - 1,4:3,6-dianhydrohexitol units (A) in a molar amount ranging from 0.5 to 33 mol %, - ethylene glycol units (B) in a molar amount ranging from 18 to 54.5 mol %, - terephthalic acid units (C) in a molar amount ranging from 45 to 55 mol %.

[0036] Depending on the application and properties desired for the 3D printed object, the thermoplastic polyester can be a semi-crystalline thermoplastic polyester or an amorphous thermoplastic polyester.

[0037] For example, if one wishes to obtain an object that is opaque and has improved mechanical properties for a particular application, the thermoplastic polyester may be semi-crystalline, so that - 1,4:3,6-dianhydrohexitol units (A) in a molar amount ranging from 0.5 to 8.5 mol %, - ethylene glycol units (B) in a molar amount ranging from 38 to 54.5 mol %, - terephthalic acid units (C) in a molar amount ranging from 45 to 55 mol %.

[0038] Advantageously, when the thermoplastic polyester is semi-crystalline, it has a molar ratio (A) / [(A)+(B)] between 0.01 and 0.15.

[0039] Conversely, if the object is required to be transparent, the thermoplastic polyester may be amorphous, - a molar amount ranging from 7 to 33 mol % of 1,4:3,6-dianhydrohexitol units (A), - ethylene glycol units in a molar amount ranging from 18 to 46.5 mol %, - terephthalic acid units (C) in a molar amount ranging from 45 to 55 mol %.

[0040] Advantageously, when the thermoplastic polyester is amorphous, it has a molar ratio (A) / [(A)+(B)] between 0.16 and 0.60.

[0041] Those skilled in the art can easily determine the analytical conditions for determining the amount of each unit of a thermoplastic polyester. For example, in the NMR spectrum of poly(ethylene-co-isosorbide terephthalate), the chemical shift associated with ethylene glycol is approximately 4.8 ppm, the chemical shift associated with the terephthalate ring is 7.8 to 8.4 ppm, and the chemical shift associated with isosorbide is 4.1 to 5.8 ppm. The amount of each unit of the polyester can be determined by integrating each signal.

[0042] When the thermoplastic polyester is semi-crystalline, it has a glass transition temperature in the range of 75 to 140°C, for example 75 to 95°C, and when the thermoplastic polyester is amorphous, it has a glass transition temperature in the range of 95 to 140°C, for example.

[0043] Glass transition temperatures and melting points are measured by conventional methods, in particular using differential scanning calorimetry (DSC) with a heating rate of 10° C. / min. The experimental protocol is described in detail in the Examples section below.

[0044] If the thermoplastic polyester used according to the present invention is semi-crystalline, it has a melting point in the range of 205 to 250°C, for example 215 to 245°C.

[0045] Advantageously, when the thermoplastic polyester is semi-crystalline, it has a heat of fusion of more than 20 J / g, preferably more than 25 J / g, the measurement of which consists in evaluating the heat of fusion by DSC by heat treating a sample of the polyester at 170°C for 16 hours, followed by heating the sample at 10°C / min.

[0046] The thermoplastic polyester of the polymer composition according to the invention has in particular a color value L of more than 45. * Advantageously, the lightness L * is greater than 50, preferably greater than 55, most preferentially greater than 60, for example greater than 62. * can be determined using a spectrophotometer according to the CIE Lab model.

[0047] Finally, the thermoplastic polyesters used according to the invention have a reduced viscosity in solution of more than 40 mL / g, preferably less than 150 mL / g, which can be measured using an Ubbelohde capillary viscometer in orthochlorophenol at 35°C after dissolving the polymer at 130°C with stirring, the concentration of polymer introduced being 5 g / L.

[0048] This test for measuring reduced viscosity in solution is perfectly suitable for determining the viscosity of viscous polymers prepared according to the process described below, depending on the choice of solvent and the concentration of polymer used.

[0049] Advantageously, if the thermoplastic polyester is semi-crystalline, it has a reduced viscosity in solution of more than 40 mL / g and less than 120 mL / g, and if the thermoplastic polyester is amorphous, it has a reduced viscosity in solution of 50 to 90 mL / g.

[0050] The semi-crystalline or amorphous nature of the thermoplastic polyester used according to the present invention is characterized by the optional presence of an endothermic melting peak in X-ray diffraction lines or differential scanning calorimetry (DSC) analysis after heat treatment for 16 hours at 170° C. Thus, if there is an endothermic melting peak in X-ray diffraction lines and differential scanning calorimetry (DSC) analysis, the thermoplastic polyester is semi-crystalline; otherwise, it is amorphous.

[0051] According to certain embodiments, one or more additional polymers can be used in a blend with the thermoplastic polyester to produce a 3D printed object.

[0052] The additional polymer may be selected from polyamides, photoresins, photopolymers, polyesters other than the polyesters according to the present invention, polystyrene, styrene copolymers, styrene-acrylonitrile copolymers, styrene-acrylonitrile-butadiene copolymers, poly(methyl methacrylate), acrylic copolymers, poly(ether-imides), poly(phenylene oxides) such as poly(2,6-dimethylphenylene oxide), poly(phenylene sulfate), poly(ester-carbonates), polycarbonates, polysulfones, polysulfone ethers, polyether-ketones, and mixtures of these polymers.

[0053] The additional polymer may also be a polymer making it possible to improve the impact properties of the polyester, in particular a functionalized polyolefin such as functionalized ethylene or propylene polymers and copolymers, core-shell copolymers or block copolymers.

[0054] In particular, the 3D printed object comprises a polymer blend of the thermoplastic polyester and one or more additional polymers, the blend comprising at least 30 wt. % of the thermoplastic polyester relative to the total weight of the blend, and preferably the one or more additional polymers are selected from polyesters such as polybutylene terephthalate (PBT), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polyethylene terephthalate PET, glycolated polyethylene terephthalate (PETg), polycarbonate (PC), polyamide (PA), acrylonitrile butadiene styrene (ABS), thermoplastic polyurethane (TPU), polyether ether ketone (PEEK), polyacrylate, etc.

[0055] If an additional polymer is used, the latter can be added, for example, when molding the thermoplastic polyester for 3D printing or when preparing the thermoplastic polyester.

[0056] One or more additives can also be added to the thermoplastic polyester to impart specific properties during the production of the 3D printed object.

[0057] Thus, examples of additives can include fillers or organic or inorganic fibers, whether nanometer-scale or not, functionalized or not. These may be silica, zeolite, glass beads or fibers, clay, mica, titanates, silicates, graphite, calcium carbonate, carbon nanotubes, wood fibers, carbon fibers, polymer fibers, proteins, cellulose fibers, lignocellulosic fibers, and non-destructured granular starch. These fillers or fibers can improve the hardness, stiffness, or surface appearance of the printed part.

[0058] The additives may also be selected from opacifiers, dyes and pigments, such as cobalt acetate and the following compounds: HS-325 Sandoplast® RED BB (a compound with an azo functional group also known as Solvent Red 195), HS-510 Sandoplast® Blue 2B, an anthraquinone, Polysynthren® Blue R, and Clariant® RSB Violet.

[0059] The additive may also be a UV inhibitor, such as a benzophenone or benzotriazole type molecule, such as the Tinuvin™ range from BASF: for example Tinuvin 326, Tinuvin P or Tinuvin 234, or a hindered amine, such as the Chimassorb™ range from BASF: for example Chimasorb 2020, Chimasorb 81 or Chimasorb 944.

[0060] The additive may also be a fire retardant or flame retardant, such as a halogenated or non-halogenated flame retardant (e.g., phosphorus-based derivatives such as Exolit® OP), or a range of melamine cyanurates (e.g., Melapur®: Melapur 200), or aluminum hydroxide or magnesium hydroxide.

[0061] Finally, the additive may be an antistatic or antiblocking agent, such as a derivative of a hydrophobic molecule, such as Incroslip™ or Incromol™ from Croda.

[0062] The thermoplastic polyester according to the invention is therefore used to manufacture 3D printed objects.

[0063] 3D printed objects can be manufactured using 3D printing techniques known to those skilled in the art.

[0064] For example, 3D printing can be performed by fused deposition modeling (FDM) or selective laser sintering. Preferentially, 3D printing is performed by fused deposition modeling.

[0065] Fused deposition modeling 3D printing specifically consists of extruding threads of thermoplastic polymer material onto a platform through a nozzle that moves on three axes: x, y, and z. The platform descends one level each time a new layer is applied until the object is completely printed.

[0066] Thus, a person skilled in the art can easily adapt the molding of the thermoplastic polyester according to the invention to enable the latter to be used according to any one of the 3D printing methods.

[0067] The thermoplastic polyester can be in the form of threads, filaments, rods, granules, pellets, or powder. For example, in the case of fused deposition modeling 3D printing, the thermoplastic polyester can be in the form of a rod or thread, preferably thread, which is then cooled and wound up. The resulting spool of thread can then be used in a 3D printing machine to manufacture an object. In another example, in the case of selective laser sintering 3D printing, the thermoplastic polyester can be in the form of a powder.

[0068] Preferentially, when the object according to the invention is manufactured by fused deposition modeling 3D printing, the properties used for 3D printing can be optimized depending on whether the thermoplastic polyester is semi-crystalline or amorphous.

[0069] Thus, during fused deposition modeling 3D printing, if the thermoplastic polyester is semi-crystalline, the print nozzle temperature is preferentially between 250°C and 275°C, and the bed has a temperature between 40°C and 75°C. If the thermoplastic polyester is amorphous, the print nozzle temperature is preferentially between 200°C and 220°C, and the bed may or may not be heated to temperatures up to 60°C.

[0070] According to certain embodiments, when an object is manufactured by fused deposition modeling 3D printing from a semi-crystalline thermoplastic polyester, the object can be recrystallized to render it opaque and improve its mechanical properties, especially its impact resistance. Recrystallization can be carried out at a temperature of 130°C to 190°C, preferably 140°C to 180°C, such as 160°C, for a period of 3 hours to 5 hours, preferentially 3.5 hours to 4.5 hours, such as 4 hours.

[0071] The thermoplastic polyesters defined above have many advantages for producing 3D printed objects.

[0072] Indeed, thermoplastic polyesters, in particular those having a molar ratio of 1.4:3.6-dianhydrohexitol units (A) / the sum of 1.4:3.6-dianhydrohexitol units (A) and ethylene glycol units (B) of at least 0.01 and a reduced viscosity in solution of more than 40 mL / g, preferably less than 120 mL / g, make it possible to obtain 3D printed objects that do not creep, do not crack and exhibit good mechanical properties, in particular impact strength.

[0073] More specifically, when the thermoplastic polyester is an amorphous thermoplastic polyester, it has a higher glass transition temperature than polymers traditionally used to manufacture 3D printed objects, thereby allowing for improved heat resistance of the resulting object.

[0074] If the thermoplastic polyester used to manufacture the 3D printed object is a semi-crystalline thermoplastic polyester, the 3D printed object will have sufficient crystallinity to be solid and stable. Advantageously, the semi-crystalline thermoplastic polyester can be recrystallized by subsequent heating to increase the crystallinity, thereby improving mechanical properties, including impact strength.

[0075] Finally, the thermoplastic polyesters according to the invention are advantageous because, when mixed with the usual polymers used in the manufacture of 3D printed objects, such as polyamides, photoresins or photopolymers, they make it possible to widen the range of properties available for the 3D printed objects.

[0076] The present invention One aspect 1. A method for manufacturing a 3D printed object, the method comprising: a) providing a thermoplastic polyester as defined above; b) molding the thermoplastic polyester obtained in the previous step; c) 3D printing an object from the molded thermoplastic polyester; and d) recovering the 3D printed object.

[0077] The shaping of step b) is adapted by the skilled person depending on the 3D printing method carried out in step c).

[0078] Therefore, the thermoplastic polyester can be arranged in the form of thread, filament, rod, granule, pellet or powder.For example, when 3D printing is performed by fused deposition modeling, the molding is advantageously a thread, in particular a spooled thread.The spooled thread can be obtained by extruding the thermoplastic polyester in the form of a thread, and then cooling and winding the thread.

[0079] 3D printing can be performed using techniques known to those skilled in the art, for example, the 3D printing process can be performed by fused deposition modeling or selective laser sintering.

[0080] According to one alternative, if the provided polyester is a semi-crystalline thermoplastic polyester, the method according to the invention may further comprise an additional step e) of recrystallization. This recrystallization step makes it possible in particular to render the 3D printed object opaque and to improve its mechanical properties, such as its impact resistance. The recrystallization step can be carried out at a temperature between 130°C and 190°C, preferably between 140°C and 180°C, such as 160°C, for a period of 3 hours to 5 hours, preferably between 3.5 hours and 4.5 hours, such as 4 hours.

[0081] The present invention One aspect The present invention relates to 3D printed objects manufactured using the thermoplastic polyesters disclosed above. The 3D printed objects may also include one or more additional polymers and one or more additives.

[0082] Thermoplastic polyesters that are particularly suitable for obtaining the polymer composition are: - introducing into a reactor monomers comprising at least one 1.4:3.6-dianhydrohexitol (A), at least one ethylene glycol (B) and at least one terephthalic acid (C), the molar ratio ((A)+(B)) / (C) being in the range of 1.05 to 1.5, the monomers either not comprising a cycloaliphatic diol or comprising a molar amount of cycloaliphatic diol units of less than 5% relative to the total amount of monomers introduced; - introducing a catalyst system into a reactor; - polymerizing said monomers to form a polyester, a first stage of oligomerization in which the reaction medium is stirred under an inert atmosphere at a temperature ranging from 235 to 280°C, advantageously from 240 to 270°C, for example 250°C; - a second stage of condensation of the oligomers formed, stirring them under vacuum at a temperature ranging from 238 to 290°C, advantageously from 250 to 270°C, for example 265°C, so as to form a polyester; - recovering the thermoplastic polyester.

[0083] If the polymer is semi-crystalline, the method may further comprise: - optionally a step of solid-phase post-condensation; - crystallizing the polymer in an inert atmosphere, preferably at 120-190°C; - a step of solid-state post-condensation under vacuum or inert gas flow, preferably at 180 to 240°C.

[0084] This first stage of the process is carried out in an inert atmosphere, i.e., under an atmosphere of at least one inert gas, which may in particular be dinitrogen. This first stage can be carried out under gas flow or under pressure, for example at a pressure of 1.05 to 8 bar.

[0085] Preferably, the pressure is in the range of 1.05 to 6 bar, most preferentially 1.5 to 5 bar, for example 2.5 bar. Under these preferred pressure conditions, the reaction of all the monomers with each other is promoted, by limiting the loss of monomers at this stage.

[0086] Prior to the first stage of oligomerization, a step of deoxygenation of the monomers is preferably carried out. This can be done, for example, by creating a vacuum after the monomers are introduced into the reactor and then introducing an inert gas such as nitrogen. This vacuum-inert gas cycle can be repeated several times, for example, 3 to 5 times. Preferably, this vacuum-nitrogen cycle is carried out at a temperature of 60 to 80°C to ensure complete melting of the reagents, especially the diol. This deoxygenation step has the advantage of improving the color properties of the polyester obtained at the end of the process.

[0087] The second stage of condensation of the oligomers is carried out under vacuum. The pressure can be continuously reduced during this second stage by using a pressure reduction gradient in stages or by using a combination of a pressure reduction gradient and stages. Preferably, at the end of this second stage, the pressure is less than 10 mbar, most preferentially less than 1 mbar.

[0088] The first stage of the polymerization process preferably has a duration ranging from 20 minutes to 5 hours. Advantageously, the second stage has a duration ranging from 30 minutes to 6 hours, the start of which stage consists of the moment when the reactor is placed under vacuum, i.e. under a pressure of less than 1 bar.

[0089] The process further comprises the step of introducing a catalyst system into the reactor, which can occur before or during the polymerization step described above.

[0090] Catalyst system refers to a catalyst or mixture of catalysts, optionally dispersed or immobilized on an inert support.

[0091] The catalyst is used in an amount suitable to obtain a high viscosity polymer to obtain the polymer composition.

[0092] An esterification catalyst is advantageously used during the oligomerization step. The esterification catalyst can be selected from tin, titanium, zirconium, hafnium, zinc, manganese, calcium, or strontium derivatives, organic catalysts such as paratoluenesulfonic acid (PTSA) or methanesulfonic acid (MSA), or mixtures of these catalysts. Examples of such compounds include those described in paragraphs

[0026] to

[0029] of U.S. Patent Application Publication No. 2011282020 (A1) and on page 5 of WO 2013 / 062408 (A1).

[0093] Preferably, a zinc derivative or a manganese, tin or germanium derivative is used during the first stage of transesterification.

[0094] As an example of amounts by weight, 10 to 500 ppm of metal contained in the catalyst system during the oligomerization stage can be used relative to the amount of monomer introduced.

[0095] At the end of the transesterification, the catalyst from the first step can optionally be blocked by adding phosphorous acid or phosphoric acid, or, as in the case of tin(IV), can be reduced with a phosphite such as triphenyl phosphite or tris(nonylphenyl) phosphite or those cited in paragraph

[0034] of U.S. Patent Application Publication No. 2011282020(A1).

[0096] The second stage of condensation of the oligomers can optionally be carried out with the addition of a catalyst. This catalyst is advantageously selected from tin derivatives, preferentially derivatives of tin, titanium, zirconium, germanium, antimony, bismuth, hafnium, magnesium, cerium, zinc, cobalt, iron, manganese, calcium, strontium, sodium, potassium, aluminum or lithium, or mixtures of these catalysts. Examples of such compounds can be, for example, those indicated in paragraphs

[0090] to

[0094] of EP 1 882 712 (B1).

[0097] Preferably, the catalyst is a derivative of tin, titanium, germanium, aluminum or antimony.

[0098] As an example of amounts by weight, 10 to 500 ppm of metal contained in the catalyst system during the oligomer condensation stage can be used relative to the amount of monomer introduced.

[0099] Most preferentially, a catalyst system is used during the first and second stages of polymerization, said system advantageously consisting of a tin-based catalyst or a mixture of tin, titanium, germanium and aluminum-based catalysts.

[0100] For example, 10 to 500 ppm by weight of metal contained in the catalyst system relative to the amount of monomer introduced can be used.

[0101] According to the preparation process, it is advantageous to use antioxidants during the polymerization step of the monomers. These antioxidants make it possible to reduce the coloration of the resulting polyester. The antioxidants can be primary and / or secondary antioxidants. The primary antioxidants can be sterically hindered phenols such as the compounds Hostanox® 03, Hostanox® 010, Hostanox® 016, Ultranox® 210, Ultranox® 276, Dovernox® 10, Dovernox® 76, Dovernox® 3114, Irganox® 1010, or Irganox® 1076, or phosphonic acids such as Irgamod® 195. The secondary antioxidants can be trivalent phosphorus-based compounds such as Ultranox® 626, Doverphos® S-9228, Hostanox® P-EPQ, or Irgafos® 168.

[0102] It is also possible to introduce into the reactor as a polymerization additive at least one compound capable of limiting unwanted etherification reactions, such as sodium acetate, tetramethylammonium hydroxide, or tetraethylammonium hydroxide.

[0103] Finally, the process involves recovering the polyester at the end of the polymerization step, which can then be packaged in easy-to-handle forms such as pellets or granules before being reshaped for 3D printing needs.

[0104] According to a variant of the synthesis process, if the thermoplastic polyester is semi-crystalline, the step of recovering the thermoplastic polyester can be followed by a step of increasing the molar mass.

[0105] The step of increasing the molar mass is carried out by post-polymerization and can consist of a step of solid-state polycondensation (SSP) of the semi-crystalline thermoplastic polyester or of reactive extrusion of the semi-crystalline thermoplastic polyester in the presence of at least one chain extender.

[0106] Thus, according to a first variant of the manufacturing process, the post-polymerization step is carried out by SSP.

[0107] SSP is generally carried out at a temperature between the glass transition temperature and the melting point of the polymer. Therefore, to carry out SSP, the polymer must be semi-crystalline. Preferably, the latter has a heat of fusion of more than 20 J / g, preferably more than 25 J / g, and the measurement of this heat of fusion consists of subjecting a sample of this polymer in solution at a lower reduced viscosity to heat treatment at 170°C for 16 hours, and then evaluating the heat of fusion by DSC by heating the sample at 10 K / min.

[0108] Advantageously, the SSP process is carried out at a temperature in the range of 180 to 250°C, preferably in the range of 190 to 230°C, which process must necessarily be carried out at a temperature below the melting point of the semi-crystalline thermoplastic polyester.

[0109] The SSP process can be carried out in an inert atmosphere, for example under nitrogen or argon or under vacuum.

[0110] According to a second variant of the manufacturing process, the post-polymerization step is carried out by reactive extrusion of the semi-crystalline thermoplastic polyester in the presence of at least one chain extender.

[0111] The chain extender is a compound containing two functional groups capable of reacting with the alcohol, carboxylic acid, and / or carboxylic acid ester functional groups of the semicrystalline thermoplastic polyester during reactive extrusion. The chain extender can be selected, for example, from compounds containing two isocyanate, isocyanurate, lactam, lactone, carbonate, epoxy, oxazoline, and imide functional groups, which may be the same or different. Chain extension of thermoplastic polyesters can be carried out in any reactor capable of mixing highly viscous media with stirring sufficiently dispersive to ensure a good interface between the molten material and the gaseous headspace of the reactor. An extrusion reactor is particularly suitable for this process.

[0112] The reactive extrusion can be carried out in any type of extruder, in particular a single screw extruder, a co-rotating twin screw extruder or a counter-rotating twin screw extruder, however it is preferred to carry out this reactive extrusion using a co-rotating extruder.

[0113] The reactive extrusion process is - introducing the polymer into an extruder to melt the polymer; - then introducing a chain extender into the molten polymer; - then reacting the polymer with a chain extender in an extruder; - then recovering the semi-crystalline thermoplastic polyester obtained in the extrusion step.

[0114] During extrusion, the temperature inside the extruder is adjusted to be higher than the melting point of the polymer, and can range from 150 to 320°C.

[0115] The resulting semi-crystalline thermoplastic polyester after the molar mass increasing step can be recovered and then packaged in an easy-to-handle form, such as pellets or granules, which can then be reshaped to suit 3D printing needs.

[0116] The invention will be more clearly understood by the following examples and figures, which are intended to be purely illustrative and do not in any way limit the scope of protection. [Example]

[0117] The properties of the polymer were investigated using the following methods.

[0118] Reduced viscosity in solution The reduced viscosity in solution is evaluated using an Ubbelohde capillary viscometer after dissolving the polymer at 130° C. under stirring in orthochlorophenol at 35° C. and at an introduced polymer concentration of 5 g / L.

[0119] DSC The thermal properties of the polyesters were measured by differential scanning calorimetry (DSC). First, the sample was heated from 10 to 300°C (10°C / min) in an open crucible under nitrogen, cooled to 10°C (10°C / min), and then heated again to 300°C under the same conditions as in the first step. The glass transition temperature was taken at the midpoint of the second heating. Any melting points were determined from the endothermic peak (peak onset) in the first heating.

[0120] Similarly, the enthalpy of fusion (area under the curve) is determined on the first heat.

[0121] For the illustrative examples set forth below, the following reagents were used:

[0122] Ethylene glycol, Aldrich

[0123] Isosorbide (purity >99.5%) Polysorb® P manufactured by Roquette Freres

[0124] Terephthalic acid (99+% purity), manufactured by Acros

[0125] Sodium acetate tetrahydrate, Aldrich

[0126] Irgamod® 195 from BASF AG (calcium phosphonate).

[0127] Germanium dioxide, Aldrich

[0128] Example 1: Use of amorphous thermoplastic polyester to manufacture 3D printed objects. An amorphous thermoplastic polyester P1 is prepared for use according to the invention in 3D printing.

[0129] A: Polymerization Add 893 g (14.4 mol) of ethylene glycol, 701 g (4.8 mol) of isosorbide, 2656 g (16 mol) of terephthalic acid, 0.7070 g of Irgamod 195 (antioxidant), 0.1825 g of sodium acetate tetrahydrate, and 0.9820 g of germanium dioxide (catalyst) to a 7 L reactor. To extract residual oxygen from the isosorbide crystals, perform four vacuum-nitrogen cycles once the temperature of the reaction medium reaches 60-80 °C.

[0130] The reaction mixture is then heated to 250°C (4°C / min) under a pressure of 2.5 bar and constant stirring (150 rpm). The degree of esterification is calculated based on the amount of distillate collected. The pressure is then reduced to 0.7 mbar over 90 minutes according to a logarithmic gradient, and the temperature is brought to 265°C.

[0131] These low pressure and low temperature conditions were maintained until a torque increase of 21 Nm over the initial torque was obtained.

[0132] Finally, a polymer rod is cast through the bottom valve of the reactor, cooled in a thermoregulated water bath at 15° C. and chopped into approximately 15 mg of granules G1.

[0133] By using such a method, contact between the heated polymer and oxygen can be avoided, and discoloration and thermal oxidative degradation can be reduced.

[0134] The resin thus obtained has a reduced viscosity in solution of 63 mL / g.

[0135] Polyester P1 1 H NMR analysis shows that it contains 31.4 mole % isosorbide relative to the diol.

[0136] Regarding the thermal properties (measured during the second heating), polyester P1 has a glass transition temperature of 112°C.

[0137] B: Extrusion of granules to form rods The granules G1 obtained in the previous step are dried under vacuum at 80° C. so that the residual moisture content is less than 150 ppm. In this example, the moisture content of the granules is 109 ppm.

[0138] The extrusion of the rods / threads is carried out in a Collin extruder equipped with a die having two holes of 2 mm diameter each, and the assembly is completed by a cooled former and a water cooling bath.

[0139] The extrusion parameters are summarized in Table 1 below.

[0140] [Table 1]

[0141] The resulting yarn has a diameter of 1.75 mm at the exit of the extruder. It is then cooled by passing hot air at 60°C, and then surface-dried and wound up.

[0142] C: Fabrication of 3D printed objects using fused deposition modeling The spool is installed in a Volumic Stream 20 Pro 3D printer.

[0143] The nozzle temperature is set at 210°C and the bed is heated to 55°C.

[0144] The resulting print is a 3D polyhedron formed by several planar pentahedrons connected at their edges.

[0145] Visual observation reveals that the produced objects are free of creep and cracks. In addition, the resulting objects are transparent and have a good surface finish.

[0146] The amorphous thermoplastic polyesters according to the invention are therefore particularly suitable for the production of prints.

[0147] Example 2: Use of semi-crystalline thermoplastic polyesters to manufacture 3D printed objects. The semi-crystalline thermoplastic polyester P2 is prepared for use according to the invention in 3D printing.

[0148] A: Polymerization 1004 g (16.2 mol) of ethylene glycol, 322 g (2.2 mol) of isosorbide, 2656 g (16 mol) of terephthalic acid, 0.7070 g of Irgamod 195 (antioxidant), 0.1825 g of sodium acetate tetrahydrate, and 0.9820 g of germanium dioxide (catalyst) are added to a 7 L reactor. Once the temperature of the reaction medium reaches 60 °C, four vacuum-nitrogen cycles are carried out to extract residual oxygen from the isosorbide crystals.

[0149] The reaction mixture is then heated to 250°C (4°C / min) under a pressure of 2.5 bar and constant stirring (150 rpm). The degree of esterification is calculated based on the amount of distillate collected. The pressure is then reduced to 0.7 mbar over 90 minutes according to a logarithmic gradient, and the temperature is brought to 265°C.

[0150] These low pressure and low temperature conditions were maintained until a torque increase of 13 Nm over the initial torque was obtained.

[0151] Finally, a polymer rod is cast through the bottom valve of the reactor, cooled in a thermoregulated water bath at 15° C. and chopped into approximately 15 mg of granules G2.

[0152] By using such a method, contact between the heated polymer and oxygen can be avoided, and discoloration and thermal oxidative degradation can be reduced.

[0153] The resin thus obtained has a reduced viscosity in solution of 57 mL / g.

[0154] Polyester P2 1 H NMR analysis shows that it contains 10.2 mole % isosorbide relative to the diol.

[0155] The granules thus obtained are subjected to a solid-state post-condensation treatment according to the following protocol: 2.8 kg of granules of the previous polymer are introduced into a 50 L rotary evaporator. The oil bath is then rapidly brought to 120 ° C, and then gradually heated to 145 ° C until optimal crystallization of the granules is obtained. This step is carried out under a nitrogen flow at a rate of 3.3 L / min. The flask is then heated to 220 ° C under a nitrogen flow of 3.3 L / min until an IV of 88 mL / g is obtained.

[0156] Regarding thermal properties, polymer P2 has a glass transition temperature of 91° C., a melting point of 222° C. and a melting enthalpy of 36 J / g.

[0157] B: Extrusion of granules to form rods The granules G2 obtained in the previous step are dried under vacuum at 80° C. so that the residual moisture content is less than 100 ppm. In this example, the moisture content of the granules is 78 ppm.

[0158] The extrusion of the rods / threads is carried out in a Collin extruder equipped with a die having two holes of 2 mm diameter each, and the assembly is completed by a cooled former and a water cooling bath.

[0159] The extrusion parameters are summarized in Table 1 below.

[0160] [Table 2]

[0161] The resulting yarn has a diameter of 1.75 mm at the exit of the extruder. It is then cooled by passing hot air at 60°C, and then surface-dried and wound up.

[0162] C: Fabrication of 3D printed objects using fused deposition modeling The spool is installed in a Volumic Stream 20 Pro 3D printer.

[0163] The nozzle temperature is set at 240°C and the bed is heated to 75°C.

[0164] The resulting print is a 3D polyhedron formed by several planar pentahedrons connected at their edges.

[0165] Visual observation reveals that the produced objects are free of creep and cracks. In addition, the resulting objects are transparent and have a good surface finish.

[0166] The semi-crystalline thermoplastic polyesters according to the invention are therefore particularly suitable for the production of prints.

Claims

1. 1. Use of a thermoplastic polyester in a 3D printing process for producing a 3D printed object, the polyester comprising: at least one 1.4:3.6-dianhydrohexitol unit (A), at least one ethylene glycol unit (B), at least one terephthalic acid unit (C), -Does not contain diethylene glycol units the ratio (A) / [(A)+(B)] is at least 0.01 and at most 0.60; the molar ratio (1.4:3.6-dianhydrohexitol units (A) + ethylene glycol units (B)) / (terephthalic acid units (C)) is 1.05 to 1.5; The polyester does not contain any cycloaliphatic diol units or contains cycloaliphatic diol units in a molar amount of less than 5% relative to the total amount of monomer units in the polyester, and has a reduced viscosity in a solution (35°C; orthochlorophenol; 5 g / L polyester) of more than 40 mL / g.

2. at least one 1.4:3.6-dianhydrohexitol unit (A), at least one ethylene glycol unit (B), at least one terephthalic acid unit (C), A 3D printed object comprising a thermoplastic polyester that does not contain diethylene glycol units, the ratio (A) / [(A)+(B)] is at least 0.01 and at most 0.60; the molar ratio (1.4:3.6-dianhydrohexitol units (A) + ethylene glycol units (B)) / (terephthalic acid units (C)) is 1.05 to 1.5; 1. A 3D printed object, wherein the polyester does not contain cycloaliphatic diol units or contains cycloaliphatic diol units in a molar amount of less than 5% relative to the total of monomer units in the polyester, and has a reduced viscosity in solution (35° C.; orthochlorophenol; 5 g / L polyester) of greater than 40 mL / g.

3. 1. A method for manufacturing a 3D printed object, comprising the steps of: a) providing a thermoplastic polyester comprising at least one 1.4:3.6-dianhydrohexitol unit (A), at least one ethylene glycol unit (B) other than the 1.4:3.6-dianhydrohexitol unit (A), and at least one terephthalic acid unit (C), the thermoplastic polyester being free of diethylene glycol units; the ratio (A) / [(A)+(B)] is at least 0.01 and at most 0.60; the molar ratio (1.4:3.6-dianhydrohexitol units (A) + ethylene glycol units (B)) / (terephthalic acid units (C)) is 1.05 to 1.5; providing a thermoplastic polyester, the polyester containing no alicyclic diol units or containing alicyclic diol units in a molar amount of less than 5% relative to the total of the monomer units in the polyester, and having a reduced viscosity in solution (35°C; orthochlorophenol; 5 g / L polyester) of greater than 40 mL / g; b) forming the thermoplastic polyester obtained in the previous step into the form of threads, filaments, rods, granules, pellets or powder; c) 3D printing an object from the molded thermoplastic polyester; d) collecting the 3D printed object.

4. The manufacturing method according to claim 3 , characterized in that the 3D printing step c) is carried out by fused deposition modeling or selective laser sintering techniques.

5. 2. The use according to claim 1, wherein the 1.4:3.6-dianhydrohexitol (A) is isosorbide.

6. A 3D printed object as described in claim 2, characterized in that the 1.4:3.6-dianhydrohexitol (A) is isosorbide.

7. The production method described in claim 3 or 4, characterized in that the 1.4:3.6-dianhydrohexitol (A) is isosorbide.

8. 6. The use according to claim 1 or 5, characterized in that the polyester does not contain cycloaliphatic diol units or contains cycloaliphatic diol units in a molar amount of less than 1% relative to the total of the monomer units in the polyester.

9. A 3D printed object as described in claim 2 or 6, characterized in that the polyester does not contain alicyclic diol units or contains alicyclic diol units in a molar amount of less than 1% relative to the total of monomer units in the polyester.

10. A method for producing a polyester as described in claim 3, 4 or 7, characterized in that the polyester does not contain alicyclic diol units or contains alicyclic diol units in a molar amount of less than 1% relative to the total number of monomer units in the polyester.

11. 9. Use according to claim 8, characterized in that the polyester does not contain 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol or mixtures of these diols.

12. The 3D printed object of claim 9, wherein the polyester does not contain 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, or mixtures of these diols.

13. The polyester, wherein the polyester is a mixture of 1,4-cyclohexanedimethanol, 1,2-cyclohexane The process according to claim 10, characterized in that it does not contain dimethanol, 1,3-cyclohexanedimethanol or a mixture of these diols.

14. 12. The use according to claim 1, 5, 8 or 11, characterized in that the 3D printed object comprises one or more additives.

15. The 3D printed object of claim 2, 6, 9 or 12, wherein the 3D printed object comprises one or more additives.

16. The manufacturing method described in claim 3, 4, 7, 10 or 13, characterized in that the 3D printed object includes one or more additives.

17. 15. The use of claim 1, 5, 8, 11 or 14, characterized in that the 3D printed object comprises a polymer blend of the thermoplastic polyester and one or more additional polymers, the blend comprising at least 30 wt% thermoplastic polyester based on the total weight of the blend, and the one or more additional polymers are selected from polybutylene terephthalate (PBT), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polyethylene terephthalate (PET), glycolated polyethylene terephthalate (PETg), polycarbonate (PC), polyamide (PA), acrylonitrile butadiene styrene (ABS), thermoplastic polyurethane (TPU), polyether ether ketone (PEEK), polyacrylate.

18. The 3D printed object of claim 2, 6, 9, 12 or 15, wherein the 3D printed object comprises a polymer blend of the thermoplastic polyester and one or more additional polymers, the blend comprising at least 30 wt% thermoplastic polyester based on the total weight of the blend, and the one or more additional polymers selected from polybutylene terephthalate (PBT), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polyethylene terephthalate PET, glycolated polyethylene terephthalate (PETg), polycarbonate (PC), polyamide (PA), acrylonitrile butadiene styrene (ABS), thermoplastic polyurethane (TPU), polyether ether ketone (PEEK), polyacrylate.

19. The method of claim 3, 4, 7, 10, 13 or 16, wherein the 3D printed object comprises a polymer blend of the thermoplastic polyester and one or more additional polymers, the blend comprising at least 30 wt% thermoplastic polyester based on the total weight of the blend, and the one or more additional polymers selected from polybutylene terephthalate (PBT), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polyethylene terephthalate PET, glycolated polyethylene terephthalate (PETg), polycarbonate (PC), polyamide (PA), acrylonitrile butadiene styrene (ABS), thermoplastic polyurethane (TPU), polyether ether ketone (PEEK), polyacrylate.

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