Aromatic polyester containing powders for powder bed fusion printing process and printed articles thereof

Abstract

The invention relates to a 3D printable powder comprising a copolymer obtained from at least one aromatic polyester or a copolymer thereof, at least one aromatic-co-aliphatic polyester, and at least one chain extender. The invention further relates to its process of preparation, as well as its use to prepare a 3D article.

Description

[0001] AROMATIC POLYESTER CONTAINING POWDERS FOR POWDER BED FUSION PRINTING PROCESS AND PRINTED ARTICLES THEREOF

[0002] The invention relates to 3D printable powders that may be used in an additive process for the preparation of a three-dimensional article. According to the invention, the 3D printable powders are prepared from at least one aromatic polyester or copolymer thereof, at least one aromatic-co-aliphatic polyester, and at least one chain extender.

[0003] A turning point has been reached in the last years with the emergence of three-dimensional (3D) printing techniques allowing the production of custom and low-cost 3D articles. Using such technique, the 3D article is produced layer by layer. For this purpose, by means of upstream computer- aided design software (CAD), the 3D structure of the 3D article to be obtained is divided up into slices. The 3D article is then created by laying down successive slices or layers of material until the entire 3D article is produced. In other words, the slices are produced one by one in the form of layers, by carrying out the following binary sequence repeatedly:

[0004] - depositing a layer of the material necessary for producing the desired article on a platform or on an existing consolidated layer, followed by

[0005] - agglomerating said layer and bonding said layer to the precedent if present in accordance with the predefined pattern.

[0006] Thus, the 3D article is constructed by superposing elementary layers that are bonded one to another.

[0007] Conventional 3D printing processes are limited to particular types of materials. These materials should be resistant to heat (i.e. no degradation should occur upon heating during the additive process), to moisture, to radiation and to weathering, and should have a slow solidification time. Importantly, the slices or layers should adhere to one another in order to produce a 3D article with satisfactory mechanical strength that will not collapse. Ideally, the material should also have a low melting temperature and an appropriate viscosity or flowability. Importantly, after the additive process, the obtained 3D articles should have the desired properties such as mechanical properties, and should be of the exact desired dimensions and shape.

[0008] The material is usually composed of polymer(s) in combination with additives that are used to tailor the properties of the material and of the resulting 3D articles. For example, dyes, fillers, antistatic agents, antinucleating agents, viscosity agents, antioxidants or flowing aids are commonly added.

[0009] The suitability of a polymer depends on its thermal and physical properties, which depend on its chemical structure. Both its melting temperature and its crystallization temperature are important since they must allow the effective sintering of the resulting powder and a satisfactory strengthening of the final 3D printed article. Ideally, the thermal conductivity is high and as well as its processing window (which is defined as the difference between the onset melting temperature and the onset crystallization temperature). A processing window of at least 10 °C seems to be required in order to be used in an additive process. Moreover, to avoid brittleness in the resulting 3D printed article, high modulus and / or strength at break and / or elongation at break are mandatory.

[0010] Another issue is the cost of these materials. Indeed, these materials and their preparation may be expensive.

[0011] Furthermore, during the additive process, a portion of the deposited layer is not agglomerated, depending on the predefined pattern. It is desirable to reuse this non-agglomerated material for the preparation of another 3D article.

[0012] The most frequently employed polymers in additive techniques such as selective laser sintering (SLS) technology are polyamides (PA), mostly polyamide 12 and polyamide 11. Other semi-crystalline polymers are used such as polypropylene, polyethylene and polyacetals. Amorphous polymers such as polycarbonates and polystyrene have also been used. Polyesters have attracted less attention compared to polyamides but could be interesting thanks to their biodegradability, their recyclability and their wide diversity of mechanical properties.

[0013] An important point in high-speed sintering, multijet fusion technology and selective laser sintering is the level of the melting temperature of the sinter powder. This should not be more than 200° C, in order firstly to minimize the energy required in the sintering operation, and secondly to assure sinterability of the sinter powder in standard laser sintering systems, which have a maximum build space temperature of about 200° C. Since pure polybutylene terephthalate (PBT), for example, has a melting temperature of about 220° C, the processing of pure polybutylene terephthalate powders in standard laser sintering systems is generally very difficult. The same also applies, for example, to pure polyethylene terephthalate (PET) powder, since pure polyethylene terephthalate likewise has a high melting temperature of more than 250° C.

[0014] Among polyesters, polyethylene terephthalate (PET) has been used in additive techniques. The use of polybutylene terephthalate (PBT) and copolymers thereof has also been reported, for example in US 2021 / 0332232, US 2021 / 0323194 and US 2023 / 0082902. Polybutylene adipate terephthalate (PBAT) has also been described, for example in CN 112300552, CN 114031914 and CN 114891324.

[0015] Patent EP 2 331 603 describes a polymer blend comprising:

[0016] - 5% to 95% by weight of a polyester comprising: i) 52 to 65 mol%, based on components i to ii, of one or more dicarboxylic acid derivatives or dicarboxylic acids selected from the group consisting of sebacic acid, azelaic acid and brassylic acid; ii) 48 to 35 mol%, based on components i to ii, of terephthalic acid derivative; iii) 92 to 102 mol%, based on component i to ii, of 1,3- propanediol or 1,4-butanediol; and iv) 0.01% to 5% by weight, based on the total weight of components i to iii, of a chain extender and / or crosslinker selected from the group consisting of a polyfunctional isocyanate, isocyanurate, oxazoline, epoxide, carboxylic anhydride and / or an at least trihydric alcohol or an at least tribasic carboxylic acid and

[0017] - 95% to 5% by weight of one or more polymer selected from the group consisting of chitosan, gluten, polybutylene succinate adipate, polybutylene succinate sebacate, polybutylene terephthalate-co-adipate; and

[0018] - 0% to 2% by weight of a compatibilizer.

[0019] This polymer blend is described as exhibiting improved biodegradability compared to PBAT. This polymer blend is in particular used to produce films or sheets.

[0020] Patent application US 2015 / 0307671 describes a polyester mixture comprising: i) 71 to 91 wt%, based on the total weight of components i and ii, of a polyester I obtained from: a.l) 40 to 70 mol%, based on component a and b, of a sebacic acid or a sebacic acid derivative; b.l) 30 to 60 mol%, based on component a and b, of terephthalic acid or a terephthalic acid derivative; c.l) 98 to 100 mol%, based on component a and b, of a C3-C6 diol; and ii) 9 to 29 wt%, based on the total weight of components i and ii, of a polyester II obtained from: a.2) 40 to 70 mol%, based on component a and b, of an adipic acid or an adipic acid derivative; b.2) 30 to 60 mol%, based on component a and b, of terephthalic acid or a terephthalic acid derivative; c.2) 98 to 100 mol%, based on component a and b, of a C3-C6 diol; and iii) 10 to 35 wt%, based on the total weight of the polymer mixture, of one or more fillers selected from talc, calcium carbonate or a mixture thereof.

[0021] The polyester mixture is used for the manufacture of agriproducts, and not for 3D printing.

[0022] The Applicant has then focused his research on aromatic polyester based powders with improved mechanical properties, and in particular improved impact resistance and elongation at break. For that purpose, the Applicant has undertaken a research program to study the compatibility and sintering behaviour of various polymers and additives, as well as the mechanical properties, the processability and the recycling of the resulting powders.

[0023] In this context, the Applicant has solved the above mentioned problems by providing a 3D printable powder made from at least one aromatic polyester or co-polymer thereof, at least one aromatic-co-aliphatic polyester, and at least one chain extender.

[0024] More precisely, the invention relates to a 3D printable powder comprising a copolymer (I) obtained from: i) 60% to 95% by weight of at least one aromatic polyester or a copolymer thereof, obtained by reacting at least one first aromatic dicarboxylic acid or a derivative thereof, with at least one first aliphatic diol, provided that no aliphatic dicarboxylic acid is used for the preparation of the at least one aromatic polyester or a copolymer thereof, ii) 5% to 40% by weight of at least one aromatic-co-aliphatic polyester, obtained by reacting at least a second aromatic dicarboxylic acid or a derivative thereof, at least one aliphatic dicarboxylic acid or a derivative thereof, and at least a second aliphatic diol, and iii) and 0,2 to 100 mmol. kg1of at least one chain extender, the weights percentages of at least one aromatic polyester or a copolymer thereof and of at least one aromatic-co-aliphatic polyester, and the amount of chain extender being relative to the total weight of aromatic polyester or copolymer thereof and of aromatic-co-aliphatic polyester.

[0025] The 3D printable powder according to the invention further has advantageously one or more of the following characteristics: the at least one first aromatic dicarboxylic acid or a derivative thereof has the following formula (A-al):

[0026] ROOC-L1-COOR' (A-al) with LI representing an unsubstituted aromatic group containing 5 to 14 carbon atoms and R and R' representing independently from one another H or a (C1-C6) alkyl group; the at least one first aromatic dicarboxylic acid or a derivative thereof is an aromatic dicarboxylic acid chosen from terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, and derivatives thereof, and mixtures thereof; the at least one first aliphatic diol is of the following formula:

[0027] HO-L2-OH (A-a2) wherein L2 represents a group chosen among: o (CH2)Zwith z being an integer ranging from 2 to 6; o (CH2-CH2-O)Z' CH2-CH2with z' being an integer ranging from 1 to 1000; o CH2-C(RIR2)CH2 with R1 and R2 being identical or different and representing a linear or branched (Cl-C6)alkyl group; o cyclohexanediyl group eventually substituted by one or more identical or different (Cl-C6)alkyl group; o cyclohexanedi methanyl group eventually substituted by one or more identical or different (Cl-C6)alkyl group; or o cyclobutanediyl group eventually substituted by one or more identical or different (Cl-C6)alkyl group; the at least one first aliphatic diol is chosen among ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-l,5-diol, hexane-1,6- diol, neopentyl glycol, 2-ethyl-2-butylpropane-l, 3-diol, 2-ethyl-2- isobutylpropane-l,3-diol, cyclohexane-l,4-dimethanol, 2,2,4- trimethylhexane-l,6-diol, polyethylene glycol, or 2, 2,4,4- tetramethylcyclobutane-l,3-diol; the at least one aromatic polyester or a copolymer thereof is polybutylene terephthalate or a copolymer of polybutylene terephthalate and neopentyl terephthalate; the at least a second aromatic dicarboxylic acid or derivative thereof is of formula (B-bl):

[0028] R3OOC-L3-COOR3' (B-bl) with L3 representing an unsubstituted aromatic group containing 5 to 14 carbon atoms and R3 and R3' representing independently from one another H or a (C1-C6) alkyl group; the at least a second aromatic dicarboxylic acid or derivative thereof is chosen among terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid and derivatives thereof and mixtures thereof; the at least one aliphatic dicarboxylic acid or derivative thereof is of formula (B-b2):

[0029] R4OOC-L5-COOR4' (B-b2) with L5 representing an unsubstituted aliphatic group containing 1 to 14 carbon atoms and R4 and R4' representing independently from one another H or a (C1-C6) alkyl group; the at least one aliphatic dicarboxylic acid or derivative thereof is chosen among adipic acid, succinic acid, glutaric acid, sebacic acid, suberic acid and azelaic acid and derivatives thereof, and mixture thereof; the at least a second aliphatic diol is of the following formula (B- b3):

[0030] HO-L4-OH (B-b3), with L4 representing: o (CH2)ywith y being an integer ranging from 2 to 6; o (CH2-CH2-O)yCH2-CH2with y' being an integer ranging from 1 to 1000; o CH2-C(R5R6)CH2with R5 and R6 being identical or different and representing a linear or branched (Cl-C6)alkyl group; o cyclohexanediyl eventually substituted by one or more identical or different (Cl-C6)alkyl group; o cyclohexanedi methanyl eventually substituted by one or more identical or different (Cl-C6)alkyl group; or o cyclobutanediyl eventually substituted by one or more identical or different (Cl-C6)alkyl group. the at least a second aliphatic diol is chosen among ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-l,5-diol, hexane-1,6- diol, neopentyl glycol, 2-ethyl-2-butylpropane-l, 3-diol, 2-ethyl-2- isobutylpropane-1, 3-diol, cyclohexane-l,4-dimethanol, 2,2,4- trimethylhexane-l,6-diol, polyethylene glycol, and 2, 2,4,4- tetramethylcyclobutane-1, 3-diol, and mixtures thereof; the at least a second aliphatic diol is chosen among ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-l,5-diol, and hexane- 1,6-diol, and mixtures thereof; the aromatic-co-aliphatic polyester is polybutylene adipate terephthalate; the epoxy chain extender is an epoxy chain extender of formula: (IV-1) or o R9, Rll, R12, R13 and R14 are identical or different and represent independently from one another H, a (C1-C6) alkyl group, o RIO represents an aromatic group, a COOR13' or a OCOR13' group with R13' being a (C1-C6) alkyl group, o R15 is a (C1-C6) alkyl group, o L7 represents a linear or branched, cyclic or acyclic alkylidene eventually comprising a -C(O)O- or -OC(O)- group, o u is an integer ranging from 0 to 100, o v is an integer ranging from 0 to 100, o u+v>0, and o w is an integer ranging from 2 to 200; the 3D printable powder further comprises one or more additives preferably selected from antioxidants, flow aids, fillers, antinucleating agents, co-crystallizers, antistatic agents, plasticizers or dyes; the 3D printable powder comprises 0.25% to 1% by weight of antioxidant, relative to the total weight of the 3D printable powder; and the antioxidant is a phenolic antioxidant, a phosphite antioxidant or a mixture thereof.

[0031] The invention further relates to a process for the preparation of the 3D printable powder according to the invention. The process of the invention comprises the following steps:

[0032] 1) providing at least one aromatic polyester or a copolymer thereof, at least one aromatic-co-aliphatic polyester, at least one chain extender, and optionally at least one additive,

[0033] 2) mixing at a temperature ranging from 150 to 350°C: i) 60% to 95% by weight of at least one aromatic polyester or a copolymer thereof, ii) 5% to 40% by weight of at least one aromatic-co- aliphatic polyester, iii) 5 to 50 mmol. kg1of at least one chain extender, iv) and optionally at least one additive, the weight percentages of at least one aromatic polyester or a copolymer thereof and of at least one aromatic-co-aliphatic polyester, and the amount of chain extender being relatives to the total weight of the at least one aromatic polyester or a copolymer thereof and the at least one aromatic-co-aliphatic polyester, to obtain granulates containing copolymer,

[0034] 3) grinding the granulates containing copolymer (I),

[0035] 4) optionally adding at least one additive and mixing, to afford the 3D printable powder.

[0036] The process of preparation of the 3D printable powder according to the invention further has advantageously one or more of the following characteristics:

[0037] - the mixing is performed in an extruder, preferably a twin-screw extruder;

[0038] - the grinding is performed with a cryo-milling apparatus; and

[0039] - the at least one additive added in step 2) is at least one antioxidant.

[0040] The invention also relates to the 3D printable powder obtained thanks to the process of the invention.

[0041] The invention further relates to a method for manufacturing a 3D article by an additive process, preferably by powder bed fusion technique such as selective laser sintering or multi-jet fusion techniques, thanks to the 3D printable powder of the invention, or thanks to the 3D printable powder obtained thanks to the process according to the invention.

[0042] The invention also relates to a three-dimensional (3D) article fabricated by powder bed fusion technique using the 3D printable powder according to the invention, or according to the 3D printable powder obtained thanks to the process according to the invention.

[0043] Finally, the invention relates to the use of a 3D printable powder according to the invention, or a 3D printable powder obtained thanks to the process of the invention, for the manufacture of a 3D article.

[0044] 3D printable powder

[0045] The invention relates to a thermoplastic 3D printable powder that comprises a copolymer I prepared by reacting: i) 60% to 95% by weight, preferably 70% to 90% by weight, more preferably 80% to 85% by weight of at least one aromatic polyester or a copolymer thereof (also named component A), ii) 5% to 40% by weight, preferably 10% to 30% by weight, more preferably 15% to 20% by weight of at least one aromatic-co- aliphatic polyester (also named component B), and iii) 0,2 to 100 mmol. kg1, preferably 1 to 50 mmol. kg1, more preferably 5 to 25 mmol. kg1of at least one chain extender (also named component C), the weight percentages of components A and B and the amount of chain extender C being relatives to the total weight of the at least one aromatic polyester or a copolymer thereof (component A) and the at least one aromatic-co-aliphatic polyester (component B).

[0046] In the context of the invention, a "3D printable powder" is a powder or pulverulent solid that is usable in a 3D printing process, such as selective laser sintering (SLS) or multi-jet fusion (MJF). Therefore, a 3D printable powder preferably has specific characteristics in order to be used in such process, such as specific melt flow index, flowability, thermal properties and granulometry as detailed below. As a consequence, a powder in the context of the invention is different from filaments, granules or pellets that may be of diameter of a few mm.

[0047] In the context of the invention, the bulk density of the 3D printable powders preferably ranges from 0.22 g / cm3to 0.55 g / cm3.

[0048] The 3D printable powders of the invention preferably have a tap density ranging from 0.27 g / cm3to 0.66 g / cm3.

[0049] The number of tap for reaching half of tap density (nl / 2) is preferably ranging from 3 to 30.

[0050] The Haussner ratio is the ratio bulk density / tap density. Preferably in the context of the invention, the Haussner ration ranges from 1.01 to 1.35.

[0051] Bulk and tap densities as well as nl / 2 and Haussner ratio may be measured with a granupack from Granutools brand, according to 1508967:2005, ASTM B527:2014 standard.

[0052] 3D printable powders preferably have a melt flow index ranging from 1 g / 10 min to 60 g / 10 min, more preferably from 3 g / 10 min to 50 g / 10 min, even more preferably ranging from 5 g / 10 min to 45 g / 10 min, at a temperature Tmfi and under a load of 2.16 kg. The melt flow index is determined according to ISO 1133:2011 standard which indicates the value of Tmfi depending on the polymer(s). For example, when polypropylene homopolymer or copolymer is only present, the temperature Tmfiis of 230°C.

[0053] In order to be successfully used in an additive process, a 3D printable powder preferably has specific thermal properties. Advantageously, its melting peak temperature Tmis at least 20 °C higher than its crystallization temperature Tc. Advantageously, its melting peak temperature Tmis at most 10 °C higher than its onset melting temperature Tmonset- Advantageously, its start melt temperature Tmstart is at least higher than the onset crystallization temperature Tconset- The melting peak temperature Tm, the crystallization temperature Tc, the onset melting temperature Tmonset, and the start melt temperature Tmstart may be determined by differential scanning calorimetry (DSC) usually at ±10°C I min.

[0054] The melting peak temperature Tmcorresponds to the temperature measured at the maximum of the peak of the thermal phenomenon corresponding to melting. The start melt temperature Tmstart corresponds to the start of the phenomenon of melting of the crystallites, i.e. when the first crystallites start to melt. The onset value corresponds to an extrapolated temperature corresponding to the intersection of the base line of the peak and of the tangent to the point with the largest slope of the first portion of the melting peak for temperatures below the maximum temperature for the peak. The onset of crystallization is determined with the same graphical method during the cooling phase. The crystallization temperature corresponds to the temperature measured at the maximum of the peak of the thermal phenomenon corresponding to crystallization.

[0055] In order to be used in an additive process, a 3D printable powder preferably has a melting peak temperature Tmfrom about 70 °C to about 250 °C, preferably from about 110 °C to about 180 °C.

[0056] In order to be used in an additive process, the processing window (i.e. the gap between the onset of the crystallisation peak and the onset of the melting peak) is advantageously of at least 10°C.

[0057] In order to be used in an additive process, a 3D printable powder advantageously has:

[0058] - a mean particle size dlO ranging from 20 pm to 60 pm,

[0059] - a mean particle size d50 ranging from 40 pm to 130 pm, and

[0060] - a mean particle size d90 ranging from 75 pm to 200 pm.

[0061] The mean particle sizes dlO, d50, d90 and d99 are the mean sizes of particles (corresponding to the highest dimension of said particles) for which 10%, 50%, 90% and 99% by volume respectively of said particles have a lower size, as measured by dry laser granulometry technique (also known as laser diffraction granulometry). When the particle is spherical, the mean particle size d50 corresponds to the mean particle diameter d50. In the context of the invention, an "aromatic polyester" and "polyfaromatic ester)" are used synonymously and designates a polymer prepared from a carboxylic acid or a derivative thereof (in particular carboxylate) and an alcohol, provided that at least one of said carboxylic acid or derivative thereof and said alcohol is aromatic. In other words, either the carboxylic acid or derivative thereof, or the alcohol, or both the carboxylic acid or derivative thereof and the alcohol is (are) aromatic(s). In the context of the invention, the carboxylic acid or derivative thereof is advantageously aromatic. In the context of the invention, the alcohol is advantageously an aliphatic alcohol.

[0062] In the context of the invention, a "copolymer of aromatic polyester" is a copolymer prepared from at least a carboxylic acid and / or derivative thereof (in particular carboxylate), and at least an alcohol, provided that either two different carboxylic acids and / or derivatives thereof or two different alcohols are used, and provided that at least one of said carboxylic acid(s) or derivative(s) thereof and said alcohol(s) is aromatic. In the context of the invention, the carboxylic acid(s) and derivative(s) thereof are advantageously aromatic. In the context of the invention, the alcohol(s) is advantageously an aliphatic alcohol.

[0063] The 3D printable powder according to the invention may further comprise one or more additives. When present, the amount of additive(s) is up to 40 wt% relative to the total weight of component A and component B. These additives may be for example chosen from anti-oxidants, fillers, antinucleating agents, co-crystallizers, antistatic agents, plasticizers, flow aids, or dyes. Such additives are commonly used by one skilled in the art and will not be further detailed.

[0064] In a particularly preferred embodiment, the 3D printable powder according to the invention comprises 0.25% to 1% by weight of antioxidant, relative to the total weight of the 3D printable powder, preferably a phenolic antioxidant, a phosphite antioxidant or a mixture thereof. Component A

[0065] In the description of the invention, "at least one aromatic polyester or copolymer thereof" and component A are used synonymously and have the same meaning. It has to be clear that in the context of the invention, these expressions mean one or more aromatic polyester, or one or more copolymer thereof, or a mixture of one or more aromatic polyester and one or more copolymer thereof. According to a first preferred embodiment, component A is an aromatic polyester. According to a second preferred embodiment, component A is an aromatic copolyester.

[0066] In the context of the invention, no aliphatic dicarboxylic acid is used for the preparation of component A. Only aromatic carboxylic acid(s) may be used for the preparation of component A.

[0067] In the context of the invention, the aromatic polyester(s) and / or copolymer(s) thereof used as component A are preferably semi-crystalline.

[0068] In the context of the invention a "semi-crystalline" polymer is a polymer that has an enthalpy of fusion after second heating AH2 of greater than 1 J / g, preferably of greater than 2 J / g. In the context of the invention, enthalpies of fusion are measured by means of differential scanning calorimetry (DSC) according to ISO 11357-4:2014 standard.

[0069] While not preferred, the aromatic polyester(s) and / or copolymer(s) thereof used as component A may be amorphous. According to this embodiment, the Tg is preferably comprised between 10°C and 90°C, preferably between 30°C and 55°C.

[0070] Component A preferably has an enthalpy of fusion after second heating AH2(A) of greater than 1 J / g, preferably of greater than 2 J / g. Component A preferably has an enthalpy of fusion after second heating AH2(A) of less than 150 J / g, preferably of less than 100 J / g and especially preferably of less than 80 J / g.

[0071] Preferably, component A has a viscosity number (VN(A)) ranging from 0.1 to 2.0 dL / g, more preferably from 0.5 to 1.8 dL / g and even more preferably from 0.6 to 1.5 dL / g. In the context of the invention, viscosity numbers are determined in a phenol / o-dichlorobenzene mixture (weight ratio 1:1 at 25° C) using ISO 1628-5:1998 standard.

[0072] Component A has preferably a melting peak temperature (TM(A)) ranging from 130 to 210° C, more preferably from 135 to 205° C and even more preferably in the range from 140 to 180° C. In the context of the invention, melting temperatures may be determined by DSC.

[0073] Preferably, component A has a weight-average molecular weight (MW(A)) ranging from 500 to 2 000 000 g / mol, more preferably from 10 000 to 300 000 g / mol and even more preferably from 20 000 to 200 000 g / mol. In the context of the invention, weight-average molecular weights are determined by means of SEC-MALLS (Size Exclusion Chromatography-Multi- Angle Laser Light Scattering) according to Chi-san Wu "Handbook of size exclusion chromatography and related techniques", second Ed., Chap. 6.

[0074] Preferably, component A has the following chemical structure: with LI and L2 as detailed below, and n representing an integer ranging from 10 to 10000.

[0075] Aromatic polyester may be prepared by all methods known to those skilled in the art. Preferably, it is prepared by reacting (typically via a polycondensation reaction):

[0076] - a first aromatic dicarboxylic acid (also named component al) and

[0077] - a first aliphatic diol (also named component a2).

[0078] In other words, an aromatic polyester according to the invention is obtained by reacting only one aromatic dicarboxylic acid or a derivative thereof (named component al), with only one aliphatic diol (named component a2).

[0079] In the context of the invention, no aliphatic dicarboxylic acid is used for the preparation of aromatic polyester. Only one aromatic dicarboxylic acid may be used for the preparation of copolymer of aromatic polyester

[0080] The molar ratio of component al to component a2 for the preparation of aromatic polyester is preferably in the range from 1:0.7 to 1:1.5, more preferably from 1:0.8 to 1:1.1, even more preferably in the range from 1:0.85 to 1:1.05.

[0081] Copolymers of aromatic polyester may be prepared by all methods known to those skilled in the art. Preferably, it is prepared by reacting (via a polycondensation reaction):

[0082] - at least one first aromatic dicarboxylic acid (also named component al), and

[0083] - at least one first aliphatic diol (also named component a2).

[0084] In other words, a copolymer of aromatic polyester is obtained by reacting one or more aromatic dicarboxylic acid(s) or derivative(s) thereof (named component al), with one or more aliphatic diol(s) (named component a2).

[0085] In the context of the invention, no aliphatic dicarboxylic acid is used to prepare a copolymer of aromatic polyester. Only aromatic dicarboxylic acid(s) is (are) used for the preparation of a copolymer of aromatic polyester.

[0086] The molar ratio of components al to component a2 for the preparation of copolymer of aromatic polyester is preferably in the range from 1:0.7 to 1:1.5, more preferably from 1:0.8 to 1:1.1, even more preferably in the range from 1:0.85 to 1:1.05.

[0087] Component al

[0088] In the context of the invention, one or more component(s) al may be used to prepare component A, but preferably only one component al is used to prepare component A. In the context of the invention, component al is an aromatic carboxylic diacid, named "first aromatic dicarboxylic acid", or a derivative thereof. To simplify, component al is often described as an aromatic carboxylic diacid (or aromatic dicarboxylic acid), but it has to be clear that derivatives thereof are also meant when these expressions are used.

[0089] In the context of the invention "dicarboxylic acid" and "carboxylic diacid" are used synonymously and have the same meaning. These expressions designate a molecule having two carboxylic acid functions (COOH).

[0090] Component al is described here as an aromatic carboxylic diacid. However, component al may also designate derivative(s) of said aromatic carboxylic diacid, and in particular aromatic carboxylic diester(s), or a mixture of said aromatic carboxylic diacid(s) and of said derivative(s) of said aromatic carboxylic diacid(s). Preferably, esters of aromatic carboxylic diacids al are (Cl-C6)alkyl esters of the aromatic dicarboxylic acids, for example the dimethyl, diethyl, di-( -propyl), diisopropyl, di-( -butyl), diisobutyl, di-( butyl), di-( -pentyl), diisopentyl or di-( -hexyl) esters of the aromatic dicarboxylic acids.

[0091] Component al is advantageously of the following formula A-al: ROOC-L1-COOR' (A-al) with LI representing a substituted or unsubstituted aromatic group and R and R' representing independently from one another H or a (C1-C6) alkyl group.

[0092] Preferably, LI is a hydrocarbonated group, i.e. it contains only H and C atoms. LI may be a group with only one aromatic ring such as phenyl, or a group with two or more fused aromatic rings such as naphthalene or anthracene groups.

[0093] Preferably, LI is an aromatic group containing 5 to 14 carbon atoms, preferably 6 to 10 carbon atoms, even more preferably 6 carbon atoms.

[0094] Preferably, LI is an unsubstituted aromatic group. While not preferred, LI may be a substituted aromatic group, and the substituent may be for example (Cl-C6)alkyl group, (Cl-C6)alkoxy group, COO(Cl-C6)alkyl group or OCO(Cl-C6)alkyl group.

[0095] In a preferred embodiment, LI is an unsubstituted aromatic group containing 5 to 14 carbon atoms, preferably 6 to 10 carbon atoms, even more preferably 6 carbon atoms.

[0096] The position of the two carboxylic groups on the aromatic group of LI is not critical, and any position may acceptable in the context of the invention. Preferably, the two carboxylic groups on the aromatic group of LI are in para position when LI is a phenyl group.

[0097] According to a preferred embodiment, R and R' are identical. According to this embodiment, R and R' preferably both represent H.

[0098] In other words, component al is preferably an aromatic dicarboxylic acid having 7 to 16 carbon atoms and preferably an aromatic dicarboxylic acid having 8 to 12 carbon atoms, more preferably an aromatic dicarboxylic acid having 8 carbon atoms. The aromatic group of the at least one first aromatic dicarboxylic acid al may be substituted by one or more substituent(s), such as (Cl-C6)alkyl group, (Cl-C6)alkoxy group, COO(C1- C6)alkyl group or OCO(Cl-C6)alkyl group. Alternatively and preferably, the aromatic group of at least one first aromatic dicarboxylic acid is unsubstituted.

[0099] The position of the two carboxylic groups (and of the substituent(s) if any) on the aromatic ring(s) is not critical and any position may be envisaged in the context of the present invention.

[0100] Component al is preferably chosen among terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, and mixtures thereof, more preferably among terephthalic acid, isophthalic acid, phthalic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylate thereof), and mixtures thereof.

[0101] According to a preferred embodiment, component al is chosen among terephthalic acid, isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid, and more preferably among terephthalic acid, isophthalic acid, and phthalic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylate thereof).

[0102] According to a particular embodiment, component al is terephthalic acid or a derivative thereof.

[0103] Component a2

[0104] In the context of the invention, one or more component(s) a2 may be used to prepare component A, but preferably only one or two component(s) a2 is (are) used to prepare component A. In the context of the invention, component a2 is an aliphatic diol, named "first aliphatic diol".

[0105] Component a2 is an aliphatic diol of the following formula A-a2:

[0106] HO-L2-OH (A-a2), wherein L2 represents a linear or branched, cyclic or acyclic aliphatic group.

[0107] In the context of the invention, L2 is a hydrocarbonated group, i.e. it contains only H and C atoms.

[0108] Preferably, L2 represents:

[0109] - (CH2)Zwith z being an integer ranging from 2 to 6;

[0110] - (CH2-CH2-O)Z'CH2-CH2with z' being an integer ranging from 1 to 1000;

[0111] - CH2-C(RIR2)CH2with R1 and R2 being identical or different and representing a linear or branched (Cl-C6)alkyl group;

[0112] - cyclohexanediyl eventually substituted by one or more identical or different (Cl-C6)alkyl group;

[0113] - cyclohexanedi methanyl eventually substituted by one or more identical or different (Cl-C6)alkyl group; or

[0114] - cyclobutanediyl eventually substituted by one or more identical or different (Cl-C6)alkyl group.

[0115] When L2 is a cyclic aliphatic group, the hydroxyl groups of component a2 may be in any position (for example, 1,2-, 1,3- or 1,4- in the case of cyclohexane diol).

[0116] Examples of components a2 that may be used in the context of the invention are ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-1,5- diol, hexane-l,6-diol, neopentyl glycol, 2-ethyl-2-butylpropane-l, 3-diol, 2- ethyl-2-isobutylpropane-l,3-diol, cyclohexane-l,4-dimethanol, 2,2,4- trimethylhexane-l,6-diol, polyethylene glycol, or 2, 2,4,4- tetramethylcyclobutane-l,3-diol.

[0117] According to an embodiment, component a2 is a cyclic aliphatic diol, preferably cyclohexane-l,4-dimethanol.

[0118] According to a preferred embodiment, component a2 is an acyclic aliphatic diol. According to this embodiment, component a2 is preferably of formula A-a2 with L2 being chosen from (CH2)Zwith z being an integer ranging from 2 to 6; (CH2-CH2-O)Z'CH2-CH2 with z' being an integer ranging from 1 to 1000; and CH2-C(RIR2)CH2with R1 and R2 being identical or different and representing a linear or branched (Cl-C6)alkyl group. More preferably according to this embodiment, component a2 of formula A-a2 with L2 being chosen from (CH2)Zwith z being an integer ranging from 2 to 6; and CH2-C(RIR2)CH2with R1 and R2 being identical or different and representing a linear or branched (Cl-C6)alkyl group. Examples of preferred components a2 according to this preferred embodiment are: propane-1, 3- diol, butane-l,4-diol, pentane-l,5-diol, hexane-l,6-diol, neopentyl glycol, 2- ethyl-2-butylpropane-l,3-diol, 2-ethyl-2-isobutylpropane-l,3-diol, and polyethylene glycol. Particularly preferred components a2 are butane-1,4- diol and neopentyl glycol that may be used alone or in combination for the preparation of component A.

[0119] Preferably, component A is prepared by reacting only one first aromatic dicarboxylic acid or a derivative thereof (al), with at least one first aliphatic diol (a2), provided that no aliphatic dicarboxylic acid is used.

[0120] According to a preferred embodiment, component A is prepared by reacting:

[0121] - terephthalic acid or (Cl-C6)alkyle terephthalate (component al) and

[0122] - at least one aliphatic diol (component a2).

[0123] In a preferred embodiment, component A is prepared by reacting:

[0124] - terephthalic acid or (Cl-C6)alkyle terephthalate (component al) and - at least two aliphatic diols (component a2) including a cyclic aliphatic diol and an acyclic aliphatic diol.

[0125] In a preferred embodiment, component A is prepared by reacting:

[0126] - terephthalic acid or (Cl-C6)alkyle terephthalate (component al) and

[0127] - at least two aliphatic diols (component a2) including neopentyl glycol and butane-l,4-diol.

[0128] According to a particularly preferred embodiment, component A is prepared by reacting:

[0129] - terephthalic acid or (Cl-C6)alkyle terephthalate (component al) and

[0130] - at least two aliphatic diols (component a2), including butane-l,4-diol and neopentyl glycol preferably in molar ratio ranging from 1:0.1 to 1:0.75, where the molar ratio of component al to component a2 is in the range from 1:0.8 to 1:1.1.

[0131] Preferably, component A is polybutylene terephthalate or a copolymer thereof. According to a first preferred embodiment, component A is polybutylene terephthalate. According to a second preferred embodiment, component A is a co-polymer of polybutylene terephthalate and neopentylene terephthalate obtained by polycondensation of neopentyl glycol, 1,4 butanediol and dimethylterephathalate or terephthalic acid. According to a third preferred embodiment, component A is a co-polymer of polybutylene terephthalate and cyclohexylene dimethyl terephthalate obtained by polycondensation of 1,4 cyclohexane dimethanol (1,4-CMD), 1,4- butanediol (1,4 BDO) and dimethylterephatalate (DMT).

[0132] Component B

[0133] "Aromatic-co-aliphatic polyester", "aromatic-co-aliphatic copolyester" and component B are used synonymously and have the same meaning. It has to be clear that in the context of the invention, all these expressions mean one or more aromatic-co-aliphatic polyester. According to a preferred embodiment, component B is one aromatic-co-aliphatic polyester.

[0134] Preferably in the context of the invention, the aromatic-co-aliphatic polyester(s) and / or copolymer(s) thereof used as component B are semicrystalline.

[0135] While not preferred, the aromatic-co-aliphatic polyester(s) and / or copolymer(s) thereof used as component B may be amorphous. According to this embodiment, the aromatic-co-aliphatic polyester(s) and / or copolymer(s) thereof preferably has a Tg comprised between 10°C and 90°C, preferably between 30°C and 55°C.

[0136] Component B preferably has an enthalpy of fusion after second heating

[0137] AH2(B) of greater than 1 J / g, preferably of greater than 2 J / g. Component B preferably has an enthalpy of fusion after second heating AH2(B) of less than 150 J / g, preferably of less than 100 J / g and especially preferably of less than

[0138] 80 J / g.

[0139] Preferably, component B has a viscosity number (VN(B)) ranging from

[0140] 0.1 to 2.0 dL / g, more preferably from 0.5 to 1.8 dL / g and even more preferably from 0.6 to 1.5 dL / g.

[0141] Component B has preferably a melting temperature (TM(B)) ranging from 130 to 250° C, more preferably from 135 to 205° C and even more preferably in the range from 140 to 180° C.

[0142] Preferably, component B has a weight-average molecular weight

[0143] (MW(B)) ranging from 2000 to 2 000 000 g / mol, more preferably from 10 000 to 300 000 g / mol and even more preferably from 20 000 to 200 000 g / mol.

[0144] The component B has advantageously the following chemical structure:

[0145] - L3 is a substituted or unsubstituted aromatic group,

[0146] - L4, L5 and L6 are identical or different and represent independently from one another a linear or branched, cyclic or acyclic aliphatic group,

[0147] - m is from 10 to 10000, et

[0148] - p is from 10 to 10000.

[0149] In the context of the present invention, the at least one aromatic-co- aliphatic copolyester (component B) is prepared by reacting (typically via a polycondensation reaction):

[0150] - at least one second aromatic dicarboxylic acid (also named component bl),

[0151] - at least one aliphatic dicarboxylic acid (also named component b2), and

[0152] - at least one second aliphatic diol (also named component b3), .

[0153] The molar ratio of (component bl + component b2) to component b3 is preferably in the range from 1: 0.7 to 1: 1:1.5, more preferably from 1:0.8 to 1:1.1.

[0154] The molar ratio of component b2 to component bl is preferably in the range from 1:0.05 to 1:1, more preferably from 1:0.1 to 1:0.7.

[0155] Component bl

[0156] In the context of the invention, one or more component(s) bl may be used to prepare component B, but preferably only one component bl is used to prepare component B. In the context of the invention, component bl is an aromatic carboxylic diacid (or aromatic dicarboxylic acid), named "second aromatic carboxylic diacid", or a derivative thereof. To simplify, component bl is often described as an aromatic carboxylic diacid (or aromatic dicarboxylic acid), but it has to be clear that derivatives thereof are also meant when these expressions are used.

[0157] Component bl is described here as an aromatic carboxylic diacid. However, component bl may also designate derivatives of said aromatic carboxylic diacid, and in particular aromatic carboxylic diesters, or a mixture of said aromatic carboxylic diacid and of said derivatives of said aromatic carboxylic diacid. Preferably, esters of aromatic carboxylic diacid bl are (Cl- C6)alkyl esters of the aromatic dicarboxylic acid, for example the dimethyl, diethyl, di-( -propyl), diisopropyl, di-( -butyl), diisobutyl, di-(f-butyl), di-( / 7- pentyl), diisopentyl or di-( -hexyl) esters of the aromatic dicarboxylic acids.

[0158] Component bl has advantageously the following chemical structure B- bl:

[0159] R3OOC-L3-COOR3' (B-bl) with L3 representing a substituted or unsubstituted aromatic group and R3 and R3' representing independently from one another H or a (C1-C6) alkyl group.

[0160] Preferably, L3 is a hydrocarbonated group, i.e. it contains only H and C atoms. L3 may be a group with only one aromatic ring such as phenyl, or a group with two or more fused aromatic rings such as naphthalene or anthracene groups.

[0161] Preferably, L3 is an aromatic group containing 5 to 14 carbon atoms, preferably 6 to 10 carbon atoms, even more preferably 6 carbon atoms.

[0162] Preferably, L3 is an unsubstituted aromatic group. While not preferred, L3 may be a substituted aromatic group, and the substituent may be for example (Cl-C6)alkyl group, (Cl-C6)alkoxy group, COO(Cl-C6)alkyl group or OCO(Cl-C6)alkyl group.

[0163] In a preferred embodiment, L3 is an unsubstituted aromatic group containing 5 to 14 carbon atoms, preferably 6 to 10 carbon atoms, even more preferably 6 carbon atoms.

[0164] The position of the two carboxylic groups on the aromatic group of L3 is not critical, and any position may acceptable in the context of the invention. Preferably, the two carboxylic groups on the aromatic group of L3 are in para position when L3 is a phenyl group.

[0165] According to a preferred embodiment, R3 and R3' are identical. According to this embodiment, R3 and R3' preferably both represent H.

[0166] In other words, component bl is preferably an aromatic dicarboxylic acid having 7 to 16 carbon atoms and preferably an aromatic dicarboxylic acid having 8 to 12 carbon atoms, more preferably an aromatic dicarboxylic acid having 8 carbon atoms. The aromatic group of the at least one second aromatic dicarboxylic acid bl may be substituted by one or more substituent, such as (Cl-C6)alkyl group, (Cl-C6)alkoxy group, COO(C1- C6)alkyl group or OCO(Cl-C6)alkyl group. Alternatively and preferably, the aromatic group of at least one aromatic dicarboxylic acid is unsubstituted.

[0167] The position of the two carboxylic groups (and of the substituent(s) if any) on the aromatic ring(s) is not critical and any position may be envisaged in the context of the present invention.

[0168] Component bl is preferably chosen among terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof), and mixtures thereof, and more preferably among terephthalic acid, isophthalic acid, phthalic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof), and mixtures thereof.

[0169] Component bl is more preferably chosen among terephthalic acid, isophthalic acid, phthalic acid and naphthalene dicarboxylic acid, and derivatives thereof, and more preferably among terephthalic acid, isophthalic acid, phthalic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof).

[0170] According to a particular embodiment, component bl is terephthalic acid or a derivative thereof (in particular (C1-C6) alkyl carboxylate thereof).

[0171] Component b2

[0172] In the context of the invention, one or more component b2 may be used to prepare component B, but preferably only one component b2 is used to prepare component B. In the context of the invention, component b2 is an aliphatic carboxylic diacid (or aliphatic dicarboxylic acid) or a derivative thereof. To simplify, component b2 is often described as an aliphatic carboxylic diacid (or aliphatic dicarboxylic acid), but it has to be clear that derivatives thereof are also meant when these expressions are used.

[0173] Component b2 is described here as an aliphatic carboxylic diacid. However, component b2 may also designate derivatives of said aliphatic carboxylic diacid, and in particular aliphatic carboxylic diesters, or a mixture of said aliphatic carboxylic diacid and of said derivatives of said aliphatic carboxylic diacid. Preferably, esters of aliphatic carboxylic diacid b2 are (Cl- C6)alkyl esters of the aliphatic dicarboxylic acids, for example the dimethyl, diethyl, di-( -propyl), diisopropyl, di-( -butyl), diisobutyl, di-(f-butyl), di-( / 7- pentyl), diisopentyl or di-( -hexyl) esters of the aliphatic dicarboxylic acids.

[0174] Component b2 is advantageously of the following formula B-b2: R4OOC-L5-COOR4' (B-b2) with L5 representing a linear or branched, cyclic or acyclic aliphatic group and R4 and R4' representing independently from one another H or a (C1-C6) alkyl group.

[0175] Preferably, L5 is a hydrocarbonated group, i.e. it contains only H and C atoms.

[0176] Preferably, L5 is an aliphatic group containing 1 to 14 carbon atoms, preferably 2 to 10 carbon atoms.

[0177] Preferably, L5 is an unsubstituted aliphatic group. While not preferred, L5 may be a substituted aliphatic group, and the substituent may be for example (Cl-C6)alkyl group, (Cl-C6)alkoxy group, COO(Cl-C6)alkyl group, or OCO(Cl-C6)alkyl group.

[0178] In a preferred embodiment, L5 is an unsubstituted aliphatic group containing 1 to 14 carbon atoms, preferably 2 to 10 carbon atoms.

[0179] The position of the two carboxylic groups on the aliphatic group L5 is not critical, and any position may acceptable in the context of the invention.

[0180] According to a preferred embodiment, R4 and R4' are identical. According to this embodiment, R4 and R4' preferably both represent H.

[0181] In other words, component b2 is preferably an unsubstituted aliphatic dicarboxylic acid having 1 to 14 carbon atoms, more preferably 2 to 10 carbon atoms, of structure B-b2 above with R4 and R4' being identical and representing preferably both H.

[0182] Component b2 is preferably chosen among adipic acid, succinic acid, glutaric acid, sebacic acid, suberic acid, azelaic acid, and derivatives thereof, and mixtures thereof, more preferably among adipic acid, succinic acid, glutaric acid, and suberic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof), and mixtures thereof.

[0183] Component b2 is preferably chosen among adipic acid, succinic acid, glutaric acid, sebacic acid, suberic acid and azelaic acid, and derivatives thereof, more preferably among adipic acid, succinic acid, glutaric acid, and suberic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof).

[0184] In a particularly preferred embodiment, component b2 is adipic acid or a derivative thereof.

[0185] Component b3

[0186] In the context of the invention, one or more component b3 may be used to prepare component B, but preferably only one component b3 is used to prepare component B. In the context of the invention, component b3 is an aliphatic diol, named "second aliphatic diol".

[0187] In the context of the invention, component b3 is at least one aliphatic diol (B-b3) of the following formula:

[0188] HO-L4-OH (B-b3), with L4 representing a linear or branched, cyclic or acyclic aliphatic group.

[0189] In the context of the invention, L4 is preferably a hydrocarbonated group, i.e. it contains only H and C atoms.

[0190] Preferably, L4 represents:

[0191] - (CH2)ywith y being an integer ranging from 2 to 6;

[0192] - (CH2-CH2-O)y'CH2-CH2with y' being an integer ranging from 1 to 1000;

[0193] - CH2-C(R5R6)CH2with R5 and R6 being identical or different and representing a linear or branched (Cl-C6)alkyl group;

[0194] - cyclohexanediyl eventually substituted by one or more identical or different (Cl-C6)alkyl group;

[0195] - cyclohexanedi methanyl eventually substituted by one or more identical or different (Cl-C6)alkyl group; or

[0196] - cyclobutanediyl eventually substituted by one or more identical or different (Cl-C6)alkyl group.

[0197] When L4 is a cyclic aliphatic group, the hydroxyl groups of component b3 may be in any position (for example, 1,2-, 1,3- or 1,4- in the case of cyclohexane diol).

[0198] Examples of components b3 that may be used in the context of the invention are ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-1,5- diol, hexane-l,6-diol, neopentyl glycol, 2-ethyl-2-butylpropane-l, 3-diol, 2- ethyl-2-isobutylpropane-l, 3-diol, cyclohexane-l,4-dimethanol, 2,2,4- trimethylhexane-l,6-diol, polyethylene glycol, and 2, 2,4,4- tetramethylcyclobutane-1, 3-diol.

[0199] According to a preferred embodiment, component b3 is an acyclic aliphatic diol. According to this embodiment, component b3 is preferably of formula B-b3 with L4 being chosen from (CH2)ywith y being an integer ranging from 2 to 6; (CH2-CH2-O)yCH2-CH2 with y' being an integer ranging from 1 to 1000; and CH2-C(R5R6)CH2 with R5 and R6 being identical or different and representing a linear or branched (Cl-C6)alkyl group. More preferably according to this embodiment, component b3 of formula B-b3 with L4 being chosen from (CH2 with y being an integer ranging from 2 to 6; and CH2-C(R5R6)CH2 with R5 and R6 being identical or different and representing a linear or branched (Cl-C6)alkyl group. Examples of preferred components b3 according to this preferred embodiment are: propane-1, 3- diol, butane-l,4-diol, pentane-l,5-diol, hexane-l,6-diol, neopentyl glycol, 2- ethyl-2-butylpropane-l, 3-diol, 2-ethyl-2-isobutylpropane-l, 3-diol, and polyethylene glycol, and more preferably ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-l,5-diol, and hexane-l,6-diol. Particularly preferred component b3 is butane-l,4-diol.

[0200] According to a first embodiment, only one aliphatic diol is used to prepare component B. According to this embodiment, component B is of the following formula: (HI-1)

[0201] According to a second embodiment, two different aliphatic diols are used to prepare component B.

[0202] According to a third embodiment, more than two aliphatic diols are used to prepare component B.

[0203] Preferably, component B is prepared by reacting:

[0204] - a second aromatic carboxylic acid (component bl) chosen among terephthalic acid, isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof),

[0205] - an aliphatic dicarboxylic acid (component b2) chosen among adipic acid, succinic acid, glutaric acid, sebacic acid, suberic acid and azelaic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof),

[0206] - a second aliphatic diol (component b3) chosen from ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-l,5-diol, hexane-l,6-diol, neopentyl glycol, 2-ethyl-2-butylpropane-l,3- diol, 2-ethyl-2-isobutylpropane-l, 3-diol, cyclohexane- 1,4- dimethanol, 2,2,4-trimethylhexane-l,6-diol, polyethylene glycol, and 2,2,4,4-tetramethylcyclobutane-l,3-diol.

[0207] Preferably, component B is prepared by reacting:

[0208] - a second aromatic carboxylic acid (component bl) chosen among terephthalic acid, isophthalic acid, and phthalic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof),

[0209] - an aliphatic dicarboxylic acid (component b2) chosen among adipic acid, succinic acid, glutaric acid, sebacic acid, suberic acid and azelaic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof),

[0210] - a second aliphatic diol (component b3) chosen from ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-l,5-diol, hexane-l,6-diol, neopentyl glycol, 2-ethyl-2-butylpropane-l,3- diol, 2-ethyl-2-isobutylpropane-l, 3-diol, cyclohexane- 1,4- dimethanol, 2,2,4-trimethylhexane-l,6-diol, and 2, 2,4,4- tetramethylcyclobutane-1, 3-diol.

[0211] Preferably, component B is prepared by reacting:

[0212] - a second aromatic carboxylic acid (component bl) chosen among terephthalic acid, isophthalic acid, and phthalic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof),

[0213] - an aliphatic dicarboxylic acid (component b2) chosen among adipic acid, succinic acid, glutaric acid, sebacic acid, suberic acid and azelaic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof),

[0214] - a second aliphatic diol (component b3) chosen from ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-l,5-diol, hexane-l,6-diol, neopentyl glycol, 2-ethyl-2-butylpropane-l,3- diol, 2-ethyl-2-isobutylpropane-l, 3-diol, 2,2,4-trimethylhexane- 1,6-diol, and 2,2,4,4-tetramethylcyclobutane-l,3-diol.

[0215] Preferably, component B is prepared by reacting:

[0216] - a second aromatic carboxylic acid (component bl) chosen among terephthalic acid, isophthalic acid, and phthalic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof), - an aliphatic dicarboxylic acid (component b2) chosen among adipic acid, succinic acid, glutaric acid, and suberic acid, and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof),

[0217] - a second aliphatic diol (component b3) chosen from ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-l,5-diol, and hexane-l,6-diol.

[0218] Preferably, component B is prepared by reacting:

[0219] - terephthalic acid (component bl), and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof),

[0220] - adipic acid (component b2), and derivatives thereof (in particular (C1-C6) alkyl carboxylates thereof),

[0221] - butane-l,4-diol (component b3).

[0222] According to a preferred embodiment, component B is a terephthalic- co-aliphatic polyester.

[0223] According to a particular embodiment, component B is polybutylene adipate terephthalate.

[0224] Component C

[0225] According to the invention, component C and "chain extender" are used synonymously and have the same meaning. In the context of the invention these expressions mean one or more chain extender(s).

[0226] Suitable chain extenders (component C) have a melting temperature (TM(C)) preferably in the range from 130 to 210° C, more preferably in the range from 135 to 205° C and especially preferably in the range from 140 to 180° C.

[0227] Preferably, component C has a weight-average molecular weight (MW(C)) in the range from 500 to 500 000 g / mol, preferably in the range from 1 000 to 200 000 g / mol and especially preferably in the range from 20 000 to 50 000 g / mol.

[0228] Preferably, component C is an epoxy chain extender. According to a first preferred embodiment, component C is an epoxy chain extender of formula IV-1: , identical or different and represent independently from one another H, a (C1-C6) alkyl group,

[0229] - RIO represents an aromatic group, a COOR13' or a OCOR13' group with R13' being a (C1-C6) alkyl group,

[0230] - L7 represents a linear or branched, cyclic or acyclic alkylidene eventually comprising a -C(O)O- or -OC(O)- group,

[0231] - v is an integer ranging from 2 to 200, and

[0232] - w is an integer ranging from 2 to 200.

[0233] According to a second preferred embodiment, component C is an epoxy chain extender of formula IV-2:

[0234] - R9, Rll, R12, R13 and R14 are identical or different and represent independently from one another H, a (C1-C6) alkyl group,

[0235] - R15 is a (C1-C6) alkyl group,

[0236] - u is an integer ranging from 0 to 100, - v is an integer ranging from 0 to 100,

[0237] - u+v>0, and

[0238] - w is an integer ranging from 2 to 200.

[0239] According to this embodiment, component C is preferably prepared by reacting (for example via a free radical reaction):

[0240] - at least one epoxy functionalized free radical monomer (also named component cl), and

[0241] - at least one aromatic or ester functionalized free radical monomer (also named component c2)

[0242] - optionally a radical initiator (also named component c3).

[0243] The molar ratio of component cl to component c2 in the preparation of component C is preferably in the range from 1:20 to 1:0, more preferably in the range from 1:10 to 1:0.

[0244] The radical initiator that may be used in the context of the invention are well known from one skilled in the art and will not be detailed.

[0245] Component cl

[0246] In the context of the invention, one or more component cl may be used to prepare component C, but preferably only one component cl is used to prepare component C. In the context of the invention, component cl is an epoxy functionalized free radical monomer, i.e. a radical monomer bearing an epoxy group.

[0247] Preferably, component cl comprises 5 to 12, more preferably 5 to 10, and even more preferably 6 carbon atoms. Preferred component cl are glycidyl methacrylate, glycidyl acrylate, 3,4-epoxycyclohexylmethyl methacrylate, and mixtures thereof. Particularly preferred component cl is glycidyl methacrylate.

[0248] Component c2

[0249] In the context of the invention, one or more component c2 may be used to prepare component C, but preferably only one or two components c2 are used to prepare component C. In the context of the invention, component c2 is an aromatic or ester functionalized free radical monomer, i.e. a radical monomer bearing an aromatic group and / or an ester group.

[0250] Preferred component c2 are methyl acrylate, methyl methacrylate, ethylacrylate, ethyl methacrylate, ethyl ethylacrylate, butyl methacrylate, styrene, alpha-methylstyrene, beta-methylstyrene, 4-methylstyrene and mixtures thereof. Particularly preferred components c2 are styrene, methyl methacrylate and mixtures thereof.

[0251] In a preferred embodiment, the component C is prepared by reacting:

[0252] - glycidyl methacrylate (component cl),

[0253] - a mixture of styrene and methyl methacrylate (component c2), preferably in a molar ratio 1:0.1 to 1:20.

[0254] According to this embodiment, the ratio of epoxy functions (from component cl) to aromatic and / or ester function (from component c2) in component C ranges preferably from 1:0 to 1:10.

[0255] Process of preparation of the 3D printable powder

[0256] The invention further relates to a process for the preparation of the 3D printable powder according to the invention.

[0257] Components A, B and C may be prepared according to any procedures known by one skilled in the art, from components al, a2, bl, b2, b3, cl and c2 as described above. Since the preparation of such components may be achieved thanks to well-known procedures, this will not be detailed.

[0258] The process of preparation of the 3D printable powder according to the invention comprises the following successive steps:

[0259] 1) providing component A, component B and component C, and optionally at least one additive,

[0260] 2) mixing at a temperature ranging from 150 to 350°C: i) 60% to 95% by weight of at least one aromatic polyester or a copolymer thereof (component A), ii) 5% to 40% by weight of at least one aromatic-co-aliphatic polyester (component B), iii) 0,2 to 100 mmol. kg1of at least one chain extender (component C), iv) and optionally at least one additive, the weight percentages of components A and B and the amount of chain extender C being relatives to the total weight of components A and B, to obtain granulates containing copolymer I,

[0261] 3) grinding the granulates containing copolymer I,

[0262] 4) optionally adding at least one additive and mixing, to afford the 3D printable powder.

[0263] The mixing in step 2) is preferably performed in an extruder, more preferably a twin-screw extruder.

[0264] The choice of which additives are added in step 2) or 4) may be done by one skilled in the art thanks to the common knowledge in the art. For example, at least one antioxidant may be added in step 2 and / or flow aids may be added in step 4.

[0265] The grinding in step 3) may be performed by dissolution followed by precipitation. Alternatively and preferably, the grinding in step 3) is performed with a cryo-milling apparatus.

[0266] Method for manufacturing a 3D article and 3D article obtained

[0267] Finally, the invention relates to a method for preparing a 3D printed article. Several additive methods may be used, among which selective laser sintering (SLS) and multi-jet fusion (MJF) techniques are particularly preferred.

[0268] The SLS technique implies the formation of superimposed layers that are bonded together by repeating the following two steps: a) depositing a continuous bed of 3D printable powder or exclusively constituted by the 3D printable powder as defined in the context of the invention, on a platform or on a previously consolidated layer; b) carrying out a localized consolidation of a portion of the deposited 3D printable powder by applying a laser beam in accordance with a predetermined pattern for each layer and simultaneously bonding the layer that has been formed thereby to the preceding consolidated layer if present, in a manner such as to cause the desired three-dimensional shape of the 3D article to grow progressively.

[0269] Advantageously, the continuous bed of 3D printable powder of step a) has a constant thickness and extends as a surface above the section of the desired 3D article taken at the level of the layer, in order to guarantee precision at the ends of the article. The thickness of the bed of powder is advantageously in the range of 40 pm to 120 pm.

[0270] The consolidation of step b) is carried out by laser treatment. To this end, it is possible to use any SLS printing machine that is known to the person skilled in the art such as for example a 3D printer of the SnowWhite type from Sharebot, the Vanguard HS type from 3D Systems, the Formiga P396 type from EOS, the Promaker P1000 type from Prodways, Formiga P110 type from EOS or HT251P type from Farsoon. By dry blending with black carbon powder or black carbon masterbatch powder, it's also possible to use 3D printer built for black materials like Lisa Pro and Lisa X from Sinterit.

[0271] The parameters of the SLS printing machine are selected in a manner such that the surface temperature of the bed of powder composition is in the sintering range, i.e. comprised between the offset crystallization temperature and the onset fusion temperature.

[0272] The MJF technique implies the formation of superimposed layers that are bonded together by repeating the following steps: a) depositing a continuous bed of 3D printable powder comprising or exclusively constituted by the 3D printable powder as defined in the context of the invention, on a platform or on a previously consolidated layer; b) applying a fusing agent in accordance with a predetermined pattern for each layer, c) carrying out a localized consolidation of a portion of the deposited 3D printable powder by application of energy.

[0273] The MJF process may also comprise the application of a detailing agent.

[0274] Fusing agents and detailing agents that may be used according to the invention are those commonly used in the art, as detailed in patent application WO 2019 / 182579 for example.

[0275] Whatever the additive process used, the 3D printable powder may be recycled. In other words, the 3D printable powder used that is not consolidated during the additive process for the preparation of a 3D printed article may be reused for the preparation of another 3D printed article. Typically, 20 wt% to 100 wt% of 3D printable powder is recycled 3D printable powder according to this embodiment. Advantageously according to this embodiment, both mechanical properties of the 3D printed article and sintering thermal properties of the 3D printable powder are same when the 3D printable powder comprise reused non consolidated 3D printable powder or only "fresh" (i.e. not reused) 3D printable powder.

[0276] The invention will now be further illustrated by the following examples that are for illustrative purpose only.

[0277] Examples

[0278] In the following examples, the granulometry in volume of the 3D printable powders were measured with a granulometer Mastersizer 3000 from Malvern. The Hausner ratio and the initial bulk density of the 3D printable powders were determined with a granular material density analyzer (GranuPack from GranuTools™) using a tapped density measurement test. Young modulus, stress at break, stress at yield, strain at yield and strain at break were measured according to NF EN ISO 527-2:2012 and ASTM D638- 08 standards. The unotched impact resilience was measured according to NF EN ISO 179-1:2010 standard. Results were obtained after a 48h conditioning at 23°C and 50% relative humidity. Intrinsic viscosities were determined in a phenol / o-dichlorobenzene mixture (weight ratio 1:1 at 25° C) according to ISO 1628-5:1998 standard. Weight-average molecular weight was determined by means of SEC-MALLS (Size Exclusion Chromatography-Multi- Angle Laser Light Scattering). Melting point, melting enthalpy and glass transition were measured in each case by differential scanning calorimetry (DSC) according to ISO 11357-4:2014 standard.

[0279] Example 1: comparative example

[0280] A co-polymer of polybutylene terephthalate and neo pentylene terephthalate (named co-PBTl hereafter) was obtained by polycondensation of neo pentyl glycol, 1,4 butanediol (1,4 BDO) and dimethylterephatalate (DMT).

[0281] A total of 100 kg of these monomers were copolymerized with the following molar feed ratio: 0.88 mol of 1,4 BDO, 0.12 mol of neo pentyl glycol and 1 mol of DMT. Monomers were mixed under nitrogen in a batch reactor at 130°C at 100 rpm with 60 ppm Tyzor TOT® (Titanium(IV) 2- ethyl hexyloxide, commercialized by Merck). When DMT is melted, temperature was raised up to 220°C during 150 minutes for the transesterification stage. When 70% of methanol were removed, the polycondensation stage was initiated by the addition of 150 ppm of phosphoric acid with increased temperature of 290°C for 120 minutes. For this stage, vacuum was applied gradually up to 40 Pa to remove unreacted monomers from transesterification and finish the product. After completion of the reaction, the obtained co-PBTl with an intrinsic viscosity of 0.8 dL / g was granulated. Weight average molar weight (Mw) of co-PBTl was 200000 g.mol1. The melting point of co-PBTl was 154°C, its melting enthalpy was 12 J / g and its glass transition was 45°C.

[0282] Granulates of co-PBTl were grinded using a cryo-milling equipment (GSM 250T KV from Gothic). The resulting powder were mixed with 0.4% Cabosil TS622 (fumed silica commercialized by Cabot) to afford a 3D printable powder PPI used as a referenced compared to the invention. Ten kg of 3D printable powder PPI were used to prepare 3D printed articles by laser sintering printing using a ProMaker P1000 S series 3D printer from Prodways. The laser parameters used were as follows: power at 10 W, hatching distance at 0.1 mm, speed at 3500 mm.s1. The chamber temperature was 146.5°C. Hl tensile specimens (using ISO 527-2:2012 standard) and impact specimens (using ISO 179-1:2010 standard) were printed and unpacked from the building cake with a good dimensional stability (no bending) after the end of printing.

[0283] Example 2: comparative example

[0284] Co-polymer of polybutylene terephthalate and neo pentylene terephthalate co-PBTl was obtained by polycondensation of neo pentyl glycol, 1,4 butanediol (1,4 BDO) and dimethylterephatalate (DMT) as described in example 1.

[0285] The following blend was produced with an industrial tumbler mixer at room temperature:

[0286] -100 kilograms of co-PBTl (component A) and

[0287] -0.5 kilogram of Joncryl ADR4400 (commercialized by BASF), a multifunctional epoxy chain extender (component C).

[0288] The dry blend obtained was introduced inside a twin-screw extruder (26 mm diameter and ten thermoregulated segments). For the melting of polymers and the optimal reaction of epoxy-chain extender, the temperature profile was: 180°C; 250°C; 250°C; 250°C; 220°C; 200°C; 200°C; 180°C; 170°C; 170°C. The screw speed was 300 rotations per minute for a 20 kg.h1throughput.

[0289] Granulates were grinded using a cryo-milling equipment (GSM 250T KV from Gothic). The resulting powder was mixed with 0.4% Alu C (commercialized by Evonik) to afford a 3D printable powder PP2.

[0290] Ten kg of 3D printable powder PP2 were used to prepare a 3D printed article by laser sintering printing using a ProMaker P1000 S series 3D printer from Prodways. The laser parameters used were as follows: power at 10 W, hatching distance at 0.1 mm, speed at 3500 mm.s1. The chamber temperature was 149.5°C. Hl tensile specimens (using ISO 527-2:2012 standard) and impact specimens (using ISO 179-1:2010 standard) were printed and unpacked from the building cake with a good dimensional stability (no bending) after the end of printing.

[0291] Example 3: example according to the invention

[0292] Co-polymer of polybutylene terephthalate and neo pentylene terephthalate co-PBTl was obtained by polycondensation of neo pentyl glycol, 1,4 butanediol (1,4 BDO) and dimethylterephatalate (DMT), as described in example 1.

[0293] The following blend was produced with an industrial tumbler mixer at room temperature:

[0294] - 85 kilograms of co-PBTl (component A),

[0295] - 15 kilograms of Ecoflex C1200 (commercialized by BASF), a statistical polybutylene adipate terephthalate (PBAT) (component B),

[0296] - 0.5 kilogram of Joncryl ADR4400 (commercialized by BASF), a multifunctional epoxy chain extender (component C), and

[0297] - 0.25 kilogram of Irganos B215 (commercialized by BASF), a 50% / 50% mixture of primary phenolic antioxidant and a secondary phosphite antioxidant.

[0298] The dry blend obtained was introduced inside a twin-screw extruder (26 mm diameter and ten thermoregulated segments). For the melt-mixing of polymers and the optimal reaction of epoxy-chain extender the temperature profile was: 180°C; 250°C; 250°C; 250°C; 220°C; 200°C; 200°C; 180°C; 170°C; 170°C. The screw speed was 300 rotations per minute for a 20 kg.h1throughput.

[0299] Granulates were grinded using a cryo-milling equipment (GSM 250 T KV commercialized by Gothic) and the resulting powder was mixed with 0.4% Alu C (aluminum oxide commercialized by Evonik) to afford a 3D printable powder PP3 according to the invention. Ten kg of 3D printable powder PP3 were used to prepare 3D printed articles by laser sintering printing using a ProMaker P1000 S series 3D printer from Prodways. The laser parameters used were as follows: power at 10 W, hatching distance at 0.1 mm, speed at 3500 mm.s1. The chamber temperature was 146°C. Hl tensile specimens (using ISO 527-2:2012 standard) and impact specimens (using ISO 179-1:2010 standard) were printed and unpacked from the building cake with a good dimensional stability (no bending) after the end of printing.

[0300] Example 4: example according to the invention

[0301] Co-polymer of polybutylene terephthalate and neo pentylene terephthalate co-PBTl was obtained by polycondensation of neo pentyl glycol, 1,4 butanediol (1,4 BDO) and dimethylterephatalate (DMT), as described in example 1.

[0302] The following blend was produced with an industrial tumbler mixer at room temperature:

[0303] - 80 kilograms of co-PBTl (component A),

[0304] - 20 kilograms of Ecoflex C1200 (commercialized by BASF), a statistical polybutylene adipate terephthalate (PBAT) (component B),

[0305] - 0.32 kilogram of Joncryl ADR 4468 (commercialized by BASF), a multifunctional epoxy chain extender (component C), and

[0306] - 0.25 kilogram of Irganos B215 (commercialized by BASF), a 50% / 50% mix of primary phenolic antioxidant and a secondary phosphite antioxidant

[0307] The dry blend obtained was introduced inside a twin-screw extruder (26 mm diameter and ten thermoregulated segments). For the melt-mixing of polymers and the optimal reaction of epoxy-chain extender the temperature profile was: 180°C; 250°C; 250°C; 250°C; 220°C; 200°C; 200°C; 180°C; 170°C; 170°C. The screw speed was 300 rotations per minute for a 20 kg.h1throughput.

[0308] Granulates were grinded using a cryo-milling equipment (GSM 250 T KV commercialized by Gothic) and the resulting powder is mixed with 0.4% Alu C (aluminum oxide commercialized by Evonik) to afford a 3D printable powder PP4 according to the invention.

[0309] Ten kg of 3D printable powder PP4 were used to prepare a 3D printed article by laser sintering printing using a ProMaker P1000 S series 3D printer from Prodways. The laser parameters used were as follows: power at 10 W, hatching distance at 0.1 mm, speed at 3500 mm.s1. The chamber temperature was 145°C. Hl tensile specimens (using ISO 527-2:2012 standard) and impact specimens (using ISO 179-1:2010 standard) were printed and unpacked from the building cake with a good dimensional stability (no bending) after the end of printing.

[0310] Example 5 : example according to the invention

[0311] A co-polymer of polybutylene terephthalate and cyclohexylene dimethyl terephthalate (PBT-co-PCT) was obtained by polycondensation of 1,4 cyclohexane dimethanol (1,4-CMD), 1,4-butanediol (1,4 BDO) and dimethylterephatalate (DMT).

[0312] A total of 100 kg of these monomers were copolymerized with the following molar feed ratio: 0.3 mole for 1,4-BDO, 0.7 mole for 1,4-CMD and 1 mole for DMT. Monomers were mixed under nitrogen in a batch reactor at 130°C at 100 rpm with 60 ppm Tyzor TOT® (Titanium(IV) 2-ethyl hexyloxide, commercialized by Merck). When DMT is melted, temperature was raised up to 220°C during 150 minutes for the transesterification stage. When 80% of methanol were removed, the polycondensation stage was initiated by the addition of 150 ppm of acid phopsphoric with increased temperature of 290°C for 120 minutes. For this stage vacuum was applied gradually up to 40 Pa to remove unreacted monomers from transesterification and finish the product. After the completion of the reaction, a PBT-co-PCT with an intrinsic viscosity of 0.9 dl / dg is granulated. The average molar weight was 100000 g.mol-1. The melting point of this PBT-co-PBT was 170°C, the melting enthalpy was 18 J / g and the glass transition temperature was 50°C.

[0313] The following blend was produced with an industrial tumbler mixer at room temperature:

[0314] - 80 kilograms of PBT-co-PCT (component A)

[0315] - 20 kilograms of Ecoflex C1200 (commercialized by BASF), a statistical polybutylene adipate terephthalate (component B)

[0316] - 0,32 kilogram of Joncryl ADR4468 (commercialized by BASF), a multifunctional epoxy chain extender (component C)

[0317] - 0,25 kilogram of Irganos B215 (commercialized by BASF), a 50% / 50% mixture of primary phenolic antioxidant and a secondary phosphite antioxidant

[0318] The dry blend obtained was introduced inside a twin-screw extruder (26 mm diameter and ten thermoregulated segments). For the melt-mixing of polymers and the optimal reaction of epoxy-chain extender the temperature profile was: 180°C ; 250°C ; 250°C ; 250°C ; 220°C ; 200°C ; 200°C ; 180°C ; 170°C ; 170°C. The screw speed was 300 rotations per minute for a 20 kg.h1throughput.

[0319] Granulates were grinded using a cryo-milling equipment (GSM 250 T KV commercialized by Gothic) and the resulting powder is mixed with 0,4% Alu C (aluminum oxide commercialized by Evonik) to afford a 3D printable powder PP5 according to the invention.

[0320] Example 6: properties of 3D printable powders PPI to PP4

[0321] The properties of the exemplified 3D printable powders PPI to PP4 were measured and are reported in Tables 1 to 3 below.

[0322] Table 1: particle size distribution of PPI to PP4

[0323] All 3D printable powders have a satisfactory particle size distribution. Table 2: Hausner ratio and initial bulk density of PPI to PP4

[0324] The bulk density and the Hausner ratio of PPI to PP4 were found similar and compatible for 3D printing applications.

[0325] Table 3: mechanical properties of PPI to PP4 PP3 and PP4 according to the invention have an improved resilience and a higher elongation compared to comparative blends PPI and PP2. Young modulus is reduced but between 1200 MPa and 1500 MPa. These modulus values are comparable to standard powder for PBF (PA11, PA12 and PP). The recycling of PP3 has also been evaluated by using 100% of recycled powder ten-times in a row. For the first printing, ten kg of 3D printable powder PP3 were used to prepare 3D printed articles by laser sintering printing using a ProMaker P1000 S series 3D printer from Prodways. The packing density, which represents the volume of printed item, was 8%. The density of sintered items is 1.24. So, to maintain the quantity for the ten printing, 1 kg of PP3 powder was added after each printing.

[0326] For the ten printing, the laser parameters used were as follows: power at 10 W, hatching distance at 0.1 mm, speed at 3500 mm.s1. The chamber temperature was 146°C for the first seven printings (1 to 7). The chamber temperature was 149°C for three last printing (8 to 10). Hl tensile specimens (using ISO 527-2:2012 standard) and impact specimens (using ISO 179-1:2010 standard) were printed and unpacked from the building cake with a good dimensional stability (no bending) after the end of printing.

[0327] Mechanical properties for each printing cycle are reported in Table 4. Table 4: recycling of PP3

[0328] The mechanical properties remain stable after 10 cycles, demonstrating that recycled PP3 may be used at least up to 10 times.

Claims

CLAIMS1 - 3D printable powder comprising a copolymer (I) obtained from : i) 60% to 95% by weight of at least one aromatic polyester or a copolymer thereof (A), obtained by reacting at least one first aromatic dicarboxylic acid or a derivative thereof (al), with at least one first aliphatic diol (a2), provided that no aliphatic dicarboxylic acid is used for the preparation of the at least one aromatic polyester or copolymer thereof (A), ii) 5% to 40% by weight of at least one aromatic-co-aliphatic polyester (B), obtained by reacting at least a second aromatic dicarboxylic acid or a derivative thereof (bl), at least one aliphatic dicarboxylic acid or a derivative thereof (b2), and at least a second aliphatic diol (b3), and iii) and 0,2 to 100 mmol. kg1of at least one chain extender (C), the weights percentages of at least one aromatic polyester or a copolymer thereof (A) and of at least one aromatic-co-aliphatic polyester (B), and the amount of chain extender (C) being relative to the total weight of aromatic polyester or copolymer thereof (A) and of aromatic-co-aliphatic polyester (B).2 - 3D printable powder according to claim 1, wherein the at least one first aromatic dicarboxylic acid or a derivative thereof (al) has the following formula (A-al):ROOC-L1-COOR' (A-al) with LI representing an unsubstituted aromatic group containing 5 to 14 carbon atoms and R and R' representing independently from one another H or a (C1-C6) alkyl group.3 - 3D printable powder according to any one of the preceding claims wherein the at least one first aromatic dicarboxylic acid or a derivative thereof (al) is an aromatic dicarboxylic acid chosen from terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, and derivatives thereof, and mixtures thereof.4 - 3D printable powder according to any one of the preceding claims, wherein the at least one first aliphatic diol (a2) is of the following formula:HO-L2-OH (A-a2) wherein L2 represents a group chosen among:- (CH2)Zwith z being an integer ranging from 2 to 6;- (CH2-CH2-O)Z- CH2-CH2with z' being an integer ranging from 1 to 1000;- CH2-C(RIR2)CH2with R1 and R2 being identical or different and representing a linear or branched (Cl-C6)alkyl group;- cyclohexanediyl group eventually substituted by one or more identical or different (Cl-C6)alkyl group;- cyclohexanedi methanyl group eventually substituted by one or more identical or different (Cl-C6)alkyl group; or- cyclobutanediyl group eventually substituted by one or more identical or different (Cl-C6)alkyl group.5 - 3D printable powder according to any one of the preceding claims wherein the at least one first aliphatic diol (a2) is chosen among ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-l,5-diol, hexane-l,6-diol, neopentyl glycol, 2-ethyl-2-butylpropane-l, 3-diol, 2-ethyl-2-isobutylpropane- 1, 3-diol, cyclohexane-l,4-dimethanol, 2,2,4-trimethylhexane-l,6-diol, polyethylene glycol, or 2,2,4,4-tetramethylcyclobutane-l,3-diol.6 - 3D printable powder according to any one of the preceding claims wherein the at least one aromatic polyester or a copolymer thereof (A) is polybutylene terephthalate or a copolymer of polybutylene terephthalate and neopentyl terephthalate.7 - 3D printable powder according to any one of the preceding claims wherein the at least a second aromatic dicarboxylic acid or derivative thereof (bl) is of formula (B-bl):R3OOC-L3-COOR3' (B-bl) with L3 representing an unsubstituted aromatic group containing 5 to 14 carbon atoms and R3 and R3' representing independently from one another H or a (C1-C6) alkyl group.8 - 3D printable powder according to any one of the preceding claims wherein the at least a second aromatic dicarboxylic acid or derivative thereof (bl) is chosen among terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid and derivatives thereof and mixtures thereof.9 - 3D printable powder according to any one of the preceding claims wherein the at least one aliphatic dicarboxylic acid or derivative thereof (b2) is of formula (B-b2):R4OOC-L5-COOR4' (B-b2) with L5 representing an unsubstituted aliphatic group containing 1 to 14 carbon atoms and R4 and R4' representing independently from one another H or a (C1-C6) alkyl group.10 - 3D printable powder according to any one of the preceding claims, wherein the at least one aliphatic dicarboxylic acid or derivative thereof (b2) is chosen among adipic acid, succinic acid, glutaric acid, sebacic acid, suberic acid and azelaic acid and derivatives thereof, and mixture thereof.11 - 3D printable powder according to any one of the preceding claims wherein the at least a second aliphatic diol (b3) is of the following formula (B-b3):H0-L4-0H (B-b3), with L4 representing:- (CH2)ywith y being an integer ranging from 2 to 6;- (CH2-CH2-O)yCH2-CH2 with y' being an integer ranging from 1 to 1000;- CH2-C(R5R6)CH2with R5 and R6 being identical or different and representing a linear or branched (Cl-C6)alkyl group;- cyclohexanediyl eventually substituted by one or more identical or different (Cl-C6)alkyl group;- cyclohexanedi methanyl eventually substituted by one or more identical or different (Cl-C6)alkyl group; or- cyclobutanediyl eventually substituted by one or more identical or different (Cl-C6)alkyl group.12 - 3D printable powder according to any one of the preceding claims wherein the at least a second aliphatic diol (b3) is chosen among ethylene glycol, propane-1, 3-diol, butane-l,4-diol, pentane-l,5-diol, and hexane-1,6- diol, and mixtures thereof.13 - 3D printable powder according to any one of the preceding claims, wherein the aromatic-co-aliphatic polyester (B) is polybutylene adipate terephthalate.14 - 3D printable powder according to any one of the preceding claims, wherein the epoxy chain extender (C) is an epoxy chain extender of formula:wherein:- R9, Rll, R12, R13 and R14 are identical or different and represent independently from one another H, a (C1-C6) alkyl group,- RIO represents an aromatic group, a COOR13' or a OCOR13' group with R13' being a (C1-C6) alkyl group,- R15 is a (C1-C6) alkyl group,- L7 represents a linear or branched, cyclic or acyclic alkylidene eventually comprising a -C(O)O- or -OC(O)- group,- u is an integer ranging from 0 to 100,- v is an integer ranging from 0 to 100,- u+v>0, and- w is an integer ranging from 2 to 200.15 - 3D printable powder according to any one of the preceding claims further comprising one or more additives preferably selected from antioxidants, flow aids, fillers, anti-nucleating agents, co-crystallizers,antistatic agents, plasticizers or dyes.16 - Process of preparation of a 3D printable powder according to any one of the preceding claims comprising the steps of:1) providing at least one aromatic polyester or a copolymer thereof (A), at least one aromatic-co-aliphatic polyester (B), at least one chain extender (C), and optionally at least one additive,2) mixing at a temperature ranging from 150 to 350°C: i) 60% to 95% by weight of at least one aromatic polyester or a copolymer thereof (A), ii) 5% to 40% by weight of at least one aromatic-co-aliphatic polyester (B), iii) 5 to 50 mmol. kg1of at least one chain extender (C), iv) and optionally at least one additive, the weight percentages of at least one aromatic polyester or a copolymer thereof (A) and of at least one aromatic-co-aliphatic polyester (B), and the amount of chain extender (C) being relatives to the total weight of the at least one aromatic polyester or a copolymer thereof (A) and the at least one aromatic-co-aliphatic polyester (B), to obtain granulates containing copolymer (I),3) grinding the granulates containing copolymer (I),4) optionally adding at least one additive and mixing, to afford the 3D printable powder.17 - Process according to the preceding claim, wherein the mixing is performed in an extruder, preferably a twin-screw extruder.18 - Method for manufacturing a 3D article by powder bed fusion technique using the 3D printable powder according to any one of claims 1 to 15, or the 3D printable powder obtained according to the process as claimed in claim 16 or 17.19 - Method according to the preceding claim wherein the powder bed fusion technique used is selective laser sintering or multi-jet fusion technique.20 - 3D article fabricated by powder bed fusion technique using the 3D printable powder according to any one of claims 1 to 15, or the 3D printable powder obtained according to the process as claimed in claim 16 or 17.21 - Use of the 3D printable powder according to anyone of claims 1 to 15, or obtained thanks to the process according to claim 16 or 17 for the manufacture of a 3D article.

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