THERMOPLASTIC POLYESTER FOR PRODUCING 3D-PRINTED OBJECTS

Abstract

The invention relates to the use of a thermoplastic polyester for producing a 3D-printed object, said 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), wherein the ratio (A)/[(A)+(B)] is at least 0.01 and at most 0.60, said polyester being free of alicyclic diol units or comprising a molar amount of alicyclic diol units, relative to the total of monomeric units in the polyester, of less than 5%, and having a reduced viscosity in solution (35° C.; orthochlorophenol; 5 g/L polyester) greater than 40 mL/g.

Claims

1. A use of a thermoplastic polyester for producing a 3D-printed object, said 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); wherein the ratio (A)/[(A)+(B)] is at least 0.01 and at most 0.60; said polyester being free of alicyclic diol units or comprising a molar amount of alicyclic diol units, relative to the total of monomeric units in the polyester, of less than 5%, and having a reduced viscosity in solution (35° C.; orthochlorophenol; 5 g/L polyester) greater than 40 mL/g.

2. A 3D-printed object comprising a thermoplastic 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); wherein the ratio (A)/[(A)+(B)] is at least 0.01 and at most 0.60; said polyester being free of alicyclic diol units or comprising a molar amount of alicyclic diol units, relative to the total of monomeric units in the polyester, of less than 5%, and having a reduced viscosity in solution (35° C.; orthochlorophenol; 5 g/L polyester) greater than 40 mL/g.

3. A method for producing a 3D-printed object comprising the following 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 units (A), at least one terephthalic acid unit (C), wherein the ratio (A)/[(A)+(B)] is at least 0.01 and at most 0.60, said polyester being free of alicyclic diol units or comprising a molar amount of alicyclic diol units, relative to the total of monomeric units in the polyester, of less than 5%, and having a reduced viscosity in solution (35° C.; orthochlorophenol; 5 g/L polyester) greater than 40 mL/g, b) Shaping the thermoplastic polyester obtained in the preceding step, c) 3D printing an object from the shaped thermoplastic polyester, d) Recovering the 3D-printed object.

4. The production method according to claim 3, wherein in step b) the thermoplastic polyester is shaped like a thread, filament, rod, granules, pellets or powder.

5. The method according to claim 3, wherein the 3D printing step c) is carried out by the fused deposition modeling technique or by the selective laser sintering technique.

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

7. The use according to claim 1 wherein the polyester is free of alicyclic diol units or comprises a molar amount of alicyclic diol units, relative to the total of monomeric units in the polyester, of less than 1%, preferably the polyester is free of alicyclic diol units.

8. The use according to claim 7, wherein the polyester is free of 1.4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol or a mixture of these diols.

9. The use according to claim 1 wherein the molar ratio (3.6-dianhydrohexitol unit (A)+ethylene glycol unit (B))/(terephthalic acid unit (C)) is from 1.05 to 1.5.

10. The use according to claim 1 wherein the 3D-printed object comprises one or more additives.

11. The use according to claim 1, wherein the 3D-printed object comprises a polymeric mixture consisting of said thermoplastic polyester and one or more additional polymers, said mixture comprising at least 30% by weight of thermoplastic polyester with respect to the total weight of said mixture, preferably said one or more additional polymers being 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), polycarbonates (PC), polyamide (PA), acrylonitrile butadiene styrene (ABS), thermoplastic polyurethane (TPU), polyetheretherketone (PEEK), polyacrylates.

Description

EXAMPLES

[0156] The properties of the polymers were studied with the following techniques:

[0157] Reduced Viscosity in Solution

[0158] The reduced viscosity in solution is assessed using an Ubbelohde capillary viscometer at 35° C. in orthochlorophenol after dissolving the polymer at 130° C. under stirring, the concentration of polymer introduced being 5 g/L.

[0159] DSC

[0160] The thermal properties of the polyesters were measured by differential scanning calorimetry (DSC): The sample is first heated under a nitrogen atmosphere in an open crucible from 10 to 300° C. (10° C.min-1), cooled to 10° C. (10° C.min-1), then heated again to 300° C. under the same conditions as the first step. The glass transition temperatures were taken at the mid-point of the second heating. Any melting points are determined on the endothermic peak (peak onset) at the first heating.

[0161] Similarly, the enthalpy of fusion (area under the curve) is determined at the first heating.

[0162] For the illustrative examples presented below, the following reagents were used:

[0163] Ethylene glycol, Aldrich

[0164] Isosorbide (purity >99.5%) Polysorb® P from Roquette Freres

[0165] Terephthalic acid (purity 99+%) from Acros

[0166] Sodium acetate tetrahydrate, Aldrich

[0167] Irgamod® 195 from BASF AG (calcium phosphonate)

[0168] Germanium dioxide, Aldrich

Example 1

Use of an Amorphous Thermoplastic Polyester for Producing a 3D-Printed Object

[0169] An amorphous thermoplastic polyester P1 is prepared for use according to the invention in 3D printing.

[0170] A: Polymerization

[0171] 893 g (14.4 mol) ethylene glycol, 701 g (4.8 mol) isosorbide, 2656 g (16 mol) terephthalic acid, 0.7070 g Irgamod 195 (antioxidant), 0.1825 g sodium acetate tetrahydrate, and 0.9820 g germanium dioxide (catalyst) are added to a 7 L reactor. To extract the residual oxygen from the isosorbide crystals, four vacuum-nitrogen cycles are performed once the temperature of the reaction medium is between 60 and 80° C.

[0172] The reaction mixture is then heated to 250° C. (4° C/min) under 2.5 bar of pressure and under constant stirring (150 rpm). The degree of esterification is estimated 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.

[0173] These low-pressure and temperature conditions were maintained until an increase in torque of 21 Nm with respect to the initial torque was obtained.

[0174] Finally, a polymer rod is cast via the bottom valve of the reactor, cooled in a heat-regulated water bath at 15° C. and chopped up in the form of granules G1 of about 15 mg.

[0175] Using such a method makes it possible to avoid contact between the heated polymer and oxygen, so as to reduce the coloration and the thermo-oxidative degradation.

[0176] The resin thus obtained has a reduced viscosity in solution of 63 mL/g.

[0177] .sup.1H NMR analysis of the polyester P1 shows that it contains 31.4% mol % of isosorbide with respect to the diols.

[0178] With regard to the thermal properties (measured during the second heating), the polyester P1 has a glass transition temperature of 112° C.

[0179] B: Extrusion of the Granules to Form a Rod

[0180] The granules G1 obtained in the previous step are dried under vacuum at 80° C. in order to achieve residual moisture levels of less than 150 ppm. For this example, the water content of the granules is 109 ppm.

[0181] The extrusion of the rod/thread is carried out on a Collin extruder equipped with a die having two holes with a diameter of 2 mm each, the assembly is completed by a cooled shaper and a water cooling bath.

[0182] The extrusion parameters are grouped together in Table 1 below:

TABLE-US-00001 TABLE 1 Parameters Units Values Temperature (supply −> ° C. 210/220/230/220/215 die): Screw rotation speed rpm 75

[0183] At the outlet of the extruder, the thread obtained has a diameter of 1.75 mm. It is then surface-dried after cooling by a flow of hot air at 60° C. and then spooled.

[0184] C: Shaping of a 3D-Printed Object by Fused Deposition Modeling

[0185] The spool is installed on a Stream 20 Pro 3D printer from the company Volumic.

[0186] The temperature of the nozzle is set at 210° C. and the bed is heated to 55° C.

[0187] The printed object obtained is a 3D polyhedron formed by several planar pentahedrons connected together by the edges.

[0188] A visual observation reveals that the produced object does not have any creep or any cracks. In addition, the object obtained is transparent and also has a good surface finish.

[0189] Thus, the amorphous thermoplastic polyester according to the invention is particularly suitable for producing a printed object.

Example 2

Use of a Semi-Crystalline Thermoplastic Polyester for Producing a 3D-Printed Object

[0190] A semi-crystalline thermoplastic polyester P2 is prepared for use according to the invention in 3D printing.

[0191] A: Polymerization

[0192] 1004 g (16.2 mol) ethylene glycol, 322 g (2.2 mol) isosorbide, 2656 g (16 mol) terephthalic acid, 0.7070 g Irgamod 195 (antioxidant), 0.1825 g sodium acetate tetrahydrate, and 0.9820 g germanium dioxide (catalyst) are added to a 7 L reactor. To extract the residual oxygen from the isosorbide crystals, four vacuum-nitrogen cycles are performed once the temperature of the reaction medium is 60° C.

[0193] The reaction mixture is then heated to 250° C. (4° C./min) under 2.5 bar of pressure and under constant stirring (150 rpm). The degree of esterification is estimated 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.

[0194] These low-pressure and temperature conditions were maintained until an increase in torque of 13 Nm with respect to the initial torque was obtained.

[0195] Finally, a polymer rod is cast via the bottom valve of the reactor, cooled in a heat-regulated water bath at 15° C. and chopped up in the form of granules G2 of about 15 mg.

[0196] Using such a method makes it possible to avoid contact between the heated polymer and oxygen, so as to reduce the coloration and the thermo-oxidative degradation.

[0197] The resin thus obtained has a reduced viscosity in solution of 57 mL/g.

[0198] .sup.1H NMR analysis of the polyester P2 shows that it contains 10.2 mol % of isosorbide with respect to the diols.

[0199] The granules thus obtained are subjected to a solid-state post-condensation treatment following the following protocol: 2.8 kg of granules of the previous polymer are introduced into a 50 L rotary evaporator. The oil of the bath is then rapidly brought to 120° C. and is then gradually heated to 145° C. until optimum crystallization of the granules is obtained. This step is carried out under a flow of nitrogen 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.

[0200] With regard to the thermal properties, the polymer P2 has a glass transition temperature of 91° C., and a melting point of 222° C. with an enthalpy of fusion of 36 J/g.

[0201] B: Extrusion of the Granules to Form a Rod

[0202] The granules G2 obtained in the previous step are dried under vacuum at 80° C. in order to achieve residual moisture levels of less than 100 ppm. For this example, the water content of the granules is 78 ppm.

[0203] The extrusion of the rod/thread is carried out on a Collin extruder equipped with a die having two holes with a diameter of 2 mm each, the assembly is completed by a cooled shaper and a water cooling bath.

[0204] The extrusion parameters are grouped together in Table 1 below:

TABLE-US-00002 TABLE 1 Parameters Units Values Temperature (supply −> ° C. 240/250/260/250/245 die): Screw rotation speed rpm 75

[0205] At the outlet of the extruder, the thread obtained has a diameter of 1.75 mm. It is then surface-dried after cooling by a flow of hot air at 60° C. and then spooled.

[0206] C: Shaping of a 3D-Printed Object by Fused Deposition Modeling

[0207] The spool is installed on a Stream 20 Pro 3D printer from the company Volumic.

[0208] The temperature of the nozzle is set at 240° C. and the bed is heated to 75° C.

[0209] The printed object obtained is a 3D polyhedron formed by several planar pentahedrons connected together by the edges.

[0210] A visual observation reveals that the produced object does not have any creep or any cracks. In addition, the object obtained is transparent and also has a good surface finish.

[0211] Thus, the semi-crystalline thermoplastic polyester according to the invention is particularly suitable for producing a printed object.