ADDITIVE MANUFACTURING METHOD FOR MAKING A THREE-DIMENSIONAL OBJECT

Abstract

The present disclosure relates to an additive manufacturing (AM) method for making a three-dimensional (3D) object, using a part material (M) comprising at least one PEEK-PEoEK copolymer, in particular to a 3D object obtainable by Fused Deposition Modelling (FDM) or Fused Filament Fabrication (FFF) from this part material (M).

Claims

1. An additive manufacturing (AM) method for making a three-dimensional (3D) object, comprising extruding a part material (M) comprising a polymer component, such polymer component comprising at least one PEEK-PEoEK copolymer, wherein the copolymer comprises at least 50 mol. %, collectively, of repeat units (R.sub.PEEK) and repeat units (R.sub.PEoEK), relative to the total number of repeat units in the PEEK-PEoEK copolymer, wherein: (a) repeat units (R.sub.PEEK) are repeat units of formula (A): ##STR00014## and (b) repeat units (R.sub.PEoEK) are repeat units of formula (B): ##STR00015## wherein each R.sup.1 and R.sup.2, equal to or different from each other, is independently at each occurrence selected from the group consisting of halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium, each a and b is independently selected from the group consisting of integers ranging from 0 to 4, and the PEEK-PEoEK copolymer comprises the repeat units R.sub.PEEK and R.sub.PEoEK in a molar ratio R.sub.PEEK/R.sub.PEoEK ranging from 95/5 to 5/95.

2. The method of claim 1, wherein the repeat units (R.sub.PEEK) are repeat units of formula: ##STR00016##

3. The method of claim 1, wherein the repeat units (R.sub.PEoEK) are repeat units of formula: ##STR00017##

4. The method of claim 1, wherein the PEEK-PEoEK copolymer is essentially composed of repeat units (R.sub.PEEK) and (R.sub.PEoEK), wherein any additional repeat unit different from repeat units R.sub.PEEK and R.sub.PEoEK, are either absent or may be present in amount of at most 2 mol. % relative to the total number of moles of repeat units in the PEEK-PEoEK copolymer.

5. The method of claim 1, wherein repeat units R.sub.PEEK and R.sub.PEoEK are present in the PEEK-PEoEK copolymer in a R.sub.PEEK/R.sub.PEoEK molar ratio ranging from 95/5 to more than 50/50.

6. The method of claim 1, wherein the part material (M) further comprises 0.1 wt. % to 60 wt. %, with respect to the total weight of the part material, of an additive selected from the group consisting of flow agents, fillers, colorants, lubricants, plasticizers, stabilizers, flame retardants, nucleating agents and combinations thereof.

7. The method of claim 1, wherein the polymer component of the part material (M) further comprises at least one polymer distinct from the PEEK-PEoEK copolymer.

8. The method of claim 1, wherein the part material (M) is the shape of a filament having a cylindrical or ribbon-like geometry, its diameter or at least one its section having a size varying between 0.5 mm and 5 mm.

9. The method of claim 1, wherein the part material (M) is the form of pellets having a size ranging from 1 mm to 1 cm.

10. The method of claim 1, wherein the part material (M) comprises a polymer component comprising: from 20 to 99 wt. % of at least one PEEK-PEoEK copolymer, and from 1 to 80 wt. % of at least one PEEK (co)polymer, based on the total weight of the polymer component.

11. A filament material having a cylindrical geometry and a diameter comprised between 0.5 and 5 mm0.15 mm, comprising a polymer component, such polymer component comprising at least one PEEK-PEoEK copolymer, wherein the copolymer comprises at least 50 mol. %, collectively, of repeat units (R.sub.PEEK) and repeat units (R.sub.PEoEK), relative to the total number of repeat units in the PEEK-PEoEK copolymer, wherein: (a) repeat units (R.sub.PEEK) are repeat units of formula (A): ##STR00018## and (b) repeat units (R.sub.PEoEK) are repeat units of formula (B): ##STR00019## wherein each R.sup.1 and R.sup.2, equal to or different from each other, is independently at each occurrence selected from the group consisting of halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium, each a and b is independently selected from the group consisting of integers ranging from 0 to 4, and the PEEK-PEoEK copolymer comprises the repeat units R.sub.PEEK and R.sub.PEoEK in a molar ratio R.sub.PEEK/R.sub.PEoEK ranging from 95/5 to 5/95.

12. The filament material of claim 11, wherein the filament is obtained by a melt-mixing process carried out by heating the polymer component above its melting temperature and melt-mixing the components of the part material.

13. The filament material of claim 11, wherein the polymer component comprises at least 80 wt. % of the PEEK-PEoEK copolymer, based on the total weight of polymeric component of the filament.

14. A three-dimensional (3D) object obtained by an extrusion-based 3D printing process, from a part material (M) comprising a polymer component, such polymer component comprising at least one PEEK-PEoEK copolymer, wherein the copolymer comprises at least 50 mol. %, collectively, of repeat units (R.sub.PEEK) and repeat units (R.sub.PEoEK), relative to the total number of repeat units in the PEEK-PEoEK copolymer, wherein: (a) repeat units (R PEEK) are repeat units of formula (A): ##STR00020## and (b) repeat units (R.sub.PEoEK) are repeat units of formula (B): ##STR00021## wherein each R.sup.1 and R.sup.2, equal to or different from each other, is independently at each occurrence selected from the group consisting of halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium, each a and b is independently selected from the group consisting of integers ranging from 0 to 4, and the PEEK-PEoEK copolymer comprises the repeat units R.sub.PEEK and R.sub.PEoEK in a molar ratio R.sub.PEEK/R.sub.PEoEK ranging from 95/5 to 5/95.

15. (canceled)

Description

EXAMPLES

[0141] The disclosure will be now described in more detail with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the disclosure.

[0142] Starting Materials

[0143] Hydroquinone, photo grade, was procured from Eastman, USA. It contained 0.38 wt % moisture, which amount was used to adapt the charge weights. All weights indicated include moisture.

[0144] Resorcinol, ACS reagent grade, was procured from Aldrich, USA 4,4-Biphenol, polymer grade, was procured from SI, USA.

[0145] Pyrocatechol, flakes, was procured from Solvay USA. Its purity was 99.85% by GC. It contained 680 ppm moisture, which amount was used to adapt the charge weights. All weights indicated include moisture. 4,4-Difluorobenzophenone, polymer grade (99.8%+), was procured from Malwa, India

[0146] Diphenyl sulfone (polymer grade) was procured from Proviron (99.8% pure).

[0147] Sodium carbonate, light soda ash, was procured from Solvay S.A., France.

[0148] Potassium carbonate with a d90<45 m was procured from Armand products.

[0149] Lithium chloride (anhydrous grade) was procured from Acros.

Preparation of Resins

[0150] PEEK

[0151] In a 500 mL 4-neck reaction flask fitted with a stirrer, a N2 inlet tube, a Claisen adapter with a thermocouple plunging in the reaction medium, and a Dean-Stark trap with a condenser and a dry ice trap were introduced 127.82 g of diphenyl sulfone, 28.685 g of hydroquinone and 57.326 g of 4,4-difluorobenzophenone.

[0152] The flask content was evacuated under vacuum and then filled with high purity nitrogen (containing less than 10 ppm O2). The reaction mixture was then placed under a constant nitrogen purge (60 mL/min).

[0153] The reaction mixture was heated slowly to 150 C. At 150 C., a mixture of 28.481 g of Na.sub.2CO.sub.3 and 0.180 g of K.sub.2CO.sub.3 was added via a powder dispenser to the reaction mixture over 30 minutes. At the end of the addition, the reaction mixture was heated to 320 C. at 1 C./minute. After 14 minutes at 320 C., the reaction was terminated in 3 stages: 6.818 g of 4,4-difluorobenzophenone were added to the reaction mixture while keeping a nitrogen purge on the reactor. After 5 minutes, 0.444 g of lithium chloride were added to the reaction mixture. 10 minutes later, another 2.273 g of 4,4-difluorobenzophenone were added to the reactor and the reaction mixture was kept at temperature for 15 minutes.

[0154] The reactor content was then poured from the reactor into a SS pan and cooled.

[0155] The solid was broken up and ground in an attrition mill through a 2 mm screen. Diphenyl sulfone and salts were extracted from the mixture with acetone and water.

[0156] The powder was then dried at 120 C. under vacuum for 12 hours yielding 65 g of a white powder.

[0157] The melt viscosity measured by capillary rheology at 400 C., 1000 s1 was 0.30 kN-s/m2

[0158] PEEK-PEoEK copolymer 80/20

[0159] In a 1000 mL 4-neck reaction flask fitted with a stirrer, a N2 inlet tube, a Claisen adapter with a thermocouple plunging in the reaction medium, and a Dean-Stark trap with a condenser and a dry ice trap were introduced 343.63 g of diphenyl sulfone, 61.852 g of hydroquinone, 15.426 g of pyrocatechol and 153.809 g of 4,4-difluorobenzophenone. The flask content was evacuated under vacuum and then filled with high purity nitrogen (containing less than 10 ppm O2). The reaction mixture was then placed under a constant nitrogen purge (60 mL/min).

[0160] The reaction mixture was heated slowly to 150 C. At 150 C., a mixture of 76.938 g of Na2CO3 and 0.484 g of K2CO3 was added via a powder dispenser to the reaction mixture over 30 minutes. At the end of the addition, the reaction mixture was heated to 320 C. at 1 C./minute. After 25 minutes at 320 C., the reaction was terminated in 3 stages: 18.329 g of 4,4-difluorobenzophenone were added to the reaction mixture while keeping a nitrogen purge on the reactor. After 5 minutes, 2.388 g of lithium chloride were added to the reaction mixture. 10 minutes later, another 6.110 g of 4,4-difluorobenzophenone were added to the reactor and the reaction mixture was kept at temperature for 15 minutes.

[0161] The reactor content was then poured from the reactor into a SS pan and cooled.

[0162] The solid was broken up and ground in an attrition mill through a 2 mm screen. Diphenyl sulfone and salts were extracted from the mixture with acetone and water.

[0163] The powder was then dried at 120 C. under vacuum for 12 hours yielding 191 g of a white powder.

[0164] The repeat unit of the polymer is:

##STR00013##

[0165] The melt viscosity measured by capillary rheology at 400 C., 1000 s1 was 0.37 kN-s/m2.

[0166] The blend PEEK/PEEK-PEoEK (formulation 3 in Table 1) was prepared by first tumbling the polymers to be compounded, in resinous form, for about 20 minutes. Then, the formulation was melt compounded using a 26 mm diameter Coperion ZSK-26 co-rotating partially intermeshing twin screw extruder having an L/D ratio of 48:1. The barrel sections 2 through 12 and the die were heated to set point temperatures as follows: Barrels 2-12: 350 C., Die: 350 C. The resin blend was fed at barrel section 1 using a gravimetric feeder at throughput rates in the range 30-40 lb/hr. The extruder was operated at screw speeds of around 200 RPM. Vacuum was applied at barrel zone 10 with a vacuum level of about 27 inches of mercury. A single-hole die was used for all the compounds to give a filament approximately 2.4 to 2.5 mm in diameter and the polymer filament exiting the die was cooled in water and fed to the pelletizer to generate pellets approximately 2.0 mm in length. Pellets were annealed prior to filament extrusion, as follows: 2 h @ 200 C.

Preparation of Filaments

[0167] Feed stocks for filament production consisted of either neat polymer (PEEK or PEEK-PEoEK) or dry blends of polymeric resin. The polymers to be extruded into filament, in resinous form, were tumbled, for about 20 minutes. Filament of diameter 1.80 mm was prepared for each composition using a Brabender Intern-Torque Plasti-Corder Torque Rheometer extruder equipped with a 0.75 (1.905 cm) 32 L/D general purpose single screw, a heated capillary die attachment, a 3/32 diameter nozzle with land of length 1.5, and downstream, custom-designed filament conveying apparatus. Other downstream equipment included a belt puller and a Dual Station Coiler, both manufactured by ESI-Extrusion Services. A Beta LaserMike 5012 with DataPro 1000 data controller was used to monitor filament dimensions. The melt strand was cooled with air. The Brabender zone set point temperatures were as follows: zone 1, 395 C.; zone 2 and zone 3, 400 C.; die, 340 C. The Brabender speed ranged from 35 to 45 rpm and the puller speed from 33 to 36 feet per minute (10.058 to 10.973 meters per minute).

[0168] 3D Printing

[0169] Filaments described above were printed on an F900 extrusion-based additive manufacturing system commercially available from Stratasys, Inc., Eden Prairie, Minnesota, USA. Filaments described above were printed as the model material, while Stratasys SUP8000B breakaway support material served as the support material. High-temp (PPSU) build sheets were employed as the printed object substrate. During the printing trials, model extruder temperature was set between 400-420 C., the support extruder temperature was set to around 400 C., and the heated chamber was set at 155 C. A Stratasys T20D tip was used for the model material, with a 0.013 layer thickness, and a Stratasys T16 tip for the support material. Model material was extruded as a series of roads in a layer-by-layer fashion to print structures in the heated chamber. A 662 mm plaque was printed for each formulation, using 100% infill and 45/45 alternating rasters, and objects were promptly removed from the heated chamber and build sheet after printing.

[0170] Test Methods

[0171] DSC (Tg, Tc, Heat of fusion)

[0172] Tg is determined on the 2.sup.nd heat scan in differential scanning calorimeter (DSC) according to ASTM D3418, using a heating and cooling rate of 20 C./min.

[0173] Tc is determined on the 1.sup.st cool scan in differential scanning calorimeter (DSC) according to ASTM D3418, using a heating and cooling rate of 20 C./min.

[0174] Heat of fusion is determined on the 2.sup.nd heat scan in differential scanning calorimeter (DSC) according to ASTM D3418, using a heating rate of 20 C./min.

[0175] Results

[0176] Table 1 provides an overview of the compositions of the filaments used in examples 1, 2, and 3.

TABLE-US-00001 TABLE 1 1 2 3 C: comparative C I I I: according to the disclosure PEEK-PEoEK 100 50 PEEK 100 50

[0177] Table 2 provides the 1.sup.st cool and 2.sup.nd heat DSC data for formulations 1, 2, and 3. The last column in Table 2 displays a (Tm-Tc)/(Tm-Tg) parameter, which is a way to compare crystallization speed between similar types of polymers (i.e. PAEKs in this case) with different glass and melting transition temperatures. The closer this number is to 0.0, the closer Tc is to Tm and the faster the crystallization speed; the closer this number is to 1.0, the closer Tc is to Tg and the slower the crystallization speed. This ratio effectively measures the supercoiling thermal driving force required to effect crystallization.

TABLE-US-00002 TABLE 2 DSC 1st cool scan DSC 2nd heat scan Compo- Tc Hc Tg Tc Hc Tm Hm (Tm-Tc)/ sition ( C.) (J/g) ( C.) ( C.) (J/g) ( C.) (J/g) (Tm-Tg) 1 PEEK 290 54 151 341 52 0.27 2 PEEK- 233 35 147 303 41 0.45 PEoEK 3 50/50 272 49 148 333 55 0.33 blend

[0178] PEEK possesses the highest relative crystallization speed at 0.27, while PEEK-PEoEK is the slowest at 0.45 and the 50/50 blend splits the difference at 0.33. In the enthalpy of melting column (Hm), the PEEK-PEoEK copolymer also possesses a lower absolute degree of crystallinity than PEEK at 41 J/g vs 52 J/g respectively, while the 50/50 blend possesses a similar degree of crystallinity to the neat PEEK at 55 vs 52 J/g).

[0179] The melting point of both the neat PEEK-PEoEK copolymer (303 C.) and a 50/50 blend of the same with PEEK (333 C.) is also advantageously lower than neat PEEK (343 C.), which provides for more facile melt processing and also a lower chance for thermal degradation as compared to neat PEEK, as all of these polymer possess similar degradation temperatures that arise from fundamentally the same ether and ketone bonds and their resulting bond dissociation energies.

[0180] 662 mm plaques were printed using the above materials. For the PEEK material, there was some undesirable warpage in the front left corner of the object, which curled upward during the printing process. The central defect in all three printed objects is a clipping used for DSC analysis of the printed part, described further below. The PEEK-PEoEK copolymer did not warp during the 3D printing process. After removal from the PPSU build sheet, it displayed a slight downward curvature. The 3D printed plaque from the 50/50 blend material advantageously lied flat both during the 3D printing process and also after removal from the PPSU build sheet, without displaying any curling or warpage.

[0181] Table 3 provides 1.sup.st heat DSC thermal transitions for clippings from the 3D printed object. The heated chamber is held at 155 C. which is very close to T g for all of these polymers.

TABLE-US-00003 TABLE 3 DSC 1st heat scan Tc Hc Tm Hm Composition ( C.) (J/g) ( C.) (J/g) 1 - printed PEEK 341 45 2 - printed PEEK-PEoEK 201 27 305 33 3 - printed 50/50 blend 185 15 337 41

[0182] The PEEK printed part is fully crystallized during the printing process, as indicated by the absence of a cold crystallization peak during the DSC 1.sup.st heat scan. The neat PEEK-PEoEK copolymer possesses a cold crystallization enthalpy (H.sub.c) of 27 J/g, whereas the 50/50 blend possesses a lower H.sub.c of 15 J/g, indicating that more of the 50/50 blend crystallized during the printing process as compared to the PEEK-PEoEK copolymer.

[0183] All the above results taken together, it is apparent that PEEK-PEoEK and a blend of the same with PEEK advantageously possesses both a lower degree of crystallinity and a slower crystallization speed than PEEK, while retaining crystallinity from the 3D printing process. Although PEEK-PEoEK and a blend of the same with PEEK partly crystallized during the 3D printing process, they surprisingly and advantageously did not warp while printing. This is contrasted with neat PEEK, which warped during the 3D printing process. This retained crystallinity of PEEK-PEoEK and its blends with PEEK is advantageous for thermal, mechanical, and chemical resistance properties of the printed part, as well as maintaining part shape should the end user decide to perform a post-printing annealing step to further increase part crystallinity.