CA3078975A1 - Composition for additive manufacturing - Google Patents

Abstract

The invention relates to a composition for additive manufacturing, characterized in that it comprises: - a polymeric mixture comprising a polyetheretherketone and a polyetherimide, and - carbon fibers.

Description

Description Title of the invention: Composition for additive manufacturing Technical area The present invention relates to the field of additive manufacturing known as also 3D printing, and more particularly to the compositions and methods useful for such technology.
Prior art In the aeronautical field, the problem of reducing the mass of materials components of aircraft in order to reduce fuel consumption leads To research new materials. In particular, it is proposed to replace the metallic structures by composites based on polymers, lighter than the metallic structures. However, the polymers must exhibit properties physico-chemical and mechanical compatible with the specifications of the field aeronautics.
Polyetheretherketones (PEEK for the English acronym Poly Ether Ether Ketone) or polyetherimides (PEI for the English acronym Poly Ether Imide) are among the polymers with high thermomechanical performance.
However, although much superior to other polymers, their properties mechanicals remain insufficient to meet the needs of the field aeronautics. To increase the mechanical resistance of polymers, it is often proposed to combine them with an additive such as nanotubes, graphene, carbon or glass fibers or even alumina.
Additive manufacturing is a manufacturing method that makes it possible to simplify considerably the manufacture of complex structures, at reduced, and compatible with many materials, including polymers. For the additive manufacturing from polymers, the layer deposition method under melted form is often used.
However, it is difficult to use, in a manufacturing process, polymers with the aforementioned additives which make it possible to reinforce their properties mechanical, because these additives adversely affect the fluidity of the polymer on the one hand, and on the other hand it is Date Received / Date Received 2020-04-21

2 often observed phenomena of clogging or even obstruction of the nozzles prints used for deposition above an additive concentration superior at 10% by mass.
It is therefore currently not possible to easily obtain by manufacturing additive a part or coating of a polymer which exhibits properties very high mechanicals.
Disclosure of the invention The invention aims precisely to respond to the aforementioned industrial problem.
In a first embodiment, the invention relates to a composition for additive manufacturing including:
- a polymeric mixture comprising a polyetheretherketone and a polyetherimide and, - carbon fibers.
Both polymers exhibit good miscibility and properties mechanical complementary. The inventors have thus observed that by mixing polyetherimides with polyetheretherketones, it is possible to obtain a polymeric mixture whose properties are particularly advantageous in terms of ease of extrusion, physicochemical properties and resistance in temperature. In particular, the glass transition temperature of the mixture polymer is greater than that of polyetheretherketone alone, and the strength of mixing required for extrusion is reduced compared to polyetherimide alone.
In addition, the introduction of carbon fibers in the polymeric mixture to to arrive at such a composition makes it possible to obtain a Young modulus very better than that of the polymer mixture while maintaining good printability, even To high carbon fiber load rates.
Carbon fibers as additives to increase the properties mechanics of the polymer mixture are also chosen because of their mass low compatible with the desired application. In addition, the fibers of carbon are not subject to entanglement phenomena, even to strong concentrations, unlike carbon nanotubes. Thus, the carbon fibers remain Date Received / Date Received 2020-04-21

3 dispersed in the polymeric mixture which makes it possible to obtain homogeneous mechanics throughout the part obtained by manufacturing additive from a composition of the invention.
Preferably, the polymeric mixture comprises at least 50% by mass of polyetheretherketone relative to the total mass of the polymer mixture.
Preferably, the polymeric mixture comprises at most 50% by mass of polyetherimide relative to the total mass of the polymer mixture.
In one embodiment, the polymeric mixture comprises between 50% and 90 %
by mass of polyetheretherketone and between 10% and 50% by mass of polyetherimide relative to the total mass of the polymer mixture.
As illustrated in the examples below, in the proportions above, the compositions obtained have a low viscosity which allows a good distribution of carbon fibers in the polymer mixture.
In addition, the surface interactions between the polyetherimide and the fibers of carbon promote a homogeneous distribution of the fibers in the polymeric mixture.
Preferably, the polymeric mixture does not comprise any polymer other than the polyetheretherketone and polyetherimide.
Alternatively, the polymeric mixture can comprise one or more other polymers such as polyetherketoneketone (PEKK), polyaryletherketone (PAEK) or even polyphenylsulfone (PPSU).
Preferably, the polyetheretherketone is chosen from polyetheretherketones having a melt viscosity of less than 90 Pa.s.
Preferably, the polyetherimide is chosen from polyetherimides having a dynamic viscosity less than 500 Pa.s at 385 C and for a rate of deformation in shear of 100 s-1.
The inventors have found that the choice of a polyetheretherketone and a low viscosity polyetherimide allows a polymeric mixture of which homogenization can be done easily. In addition, this low viscosity from polymers allows the composition to remain compatible with additive manufacturing even at high carbon fiber concentrations.
Date Received / Date Received 2020-04-21

4 Preferably, the composition comprises a higher concentration of preferably strictly greater than 30% by mass of carbon fibers per relative to the total mass of the polymer mixture. Better the composition understand a mass concentration of fibers between strictly more than 30%
and 50% by mass relative to the total mass of the polymeric mixture. Thereby he emerges from the examples below, such a concentration of carbon fibers allow to increase the mechanical properties of the composition while maintaining a viscosity compatible with additive manufacturing processes.
Preferably, the carbon fibers have a length varying from 25 µm to 25 mm.
Such a choice of fiber length allows, on the one hand, good printability.
of the composition, in particular avoiding the phenomena of head obstruction printing and also ensures good rigidity to the product obtained by additive manufacturing.
In another embodiment, the invention relates to a method of manufacturing of a part or of a coating by an additive manufacturing process including at least one step of depositing a composition as described above under melted form.
For example, the deposit of the composition can take place in the form of a deposit successive filaments of composition in molten form.
Preferably, the method of manufacturing a part or a coating by a additive manufacturing process further comprises, and prior to step of deposit of the composition, a step of extruding the composition.
This extrusion step makes it possible to obtain a homogeneous dispersion of the fibers of carbon in the polymer mixture, and thus guarantee the homogeneity of the rooms or coatings obtained.
Preferably, the extrusion is carried out between 360 C and 420 C. This choice allows to ensure good fluidity of the polymeric mixture during the step extrusion and ensures a homogeneous mixture of carbon fibers in the polymeric mixture.
The additive manufacturing process described above allows indifferently to get a part or a coating on the surface of a substrate thanks to the composition of invention.
Date Received / Date Received 2020-04-21

5 The invention is not limited either by the shape or the size of the parts to be get, neither by the nature of the substrates which can be coated.
According to another of its aspects, the invention relates to a manufacturing process of a part or a coating by additive manufacturing comprising at least one step of deposit of a composition as defined above.
Preferably, in one embodiment, such a method may comprise, prior to the deposition step, a step of extruding a composition such as described above.
For example, such an extrusion can be carried out at a temperature of Between 360 C and 420 C
According to aspects of the invention also relates to the printing of parts aeronautics using a composition as described above. In particular of such aeronautical parts can be: composites with high properties mechanical, structures printed on a curved composite substrate, acoustic panels composite brackets, molds for setting form composites by resin transfer molding.
Brief description of the drawings [Fig. 1] FIG. 1 diagrammatically represents a step of a method according to a embodiment of the invention.
[Fig. 2] FIG. 2 diagrammatically represents a step of a method according to a embodiment of the invention.
[Fig. 3] Figure 3 is a photograph obtained by electron microscopy To sweeping of a composition according to one embodiment after extrusion.
[Fig. 4] Figure 4 is a photograph obtained by electron microscopy To scanning of a filament obtained by additive manufacturing from a composition according to the invention.
[Fig. 5] FIG. 5 is a result of thermogravimetry analysis relating to example 4.
[Fig. 4] FIG. 6 is a result of thermogravimetry analysis relating to example 4.
Date Received / Date Received 2020-04-21

6 Description of the embodiments The invention will now be described by means of the figures which are not present for illustrative purposes and should not be interpreted as limiting invention.
As described above the present invention relates to a composition for additive manufacturing comprising a polymeric mixture, comprising a polyetheretherketone and polyetherimide, and carbon fibers.
As specified above, the polyetheretherketones are preferably chosen among those having a viscosity of less than 90 Pa.s in the molten state, for example example at 400 C. As such, the polyetheretherketone available under the name commercial Victrex 90G, is suitable for the invention.
Likewise, the polyetherimides are preferably chosen from those having a viscosity less than 500 Pa.s at 385 C with a deformation rate in shear from 100 s-1. As such, the polyetherimide available under the name commercial Ultem 1010, is suitable for the invention.
The composition further comprises carbon fibers. For example, fibers carbon available under the trade name CF-Zoltek PX35-85, which have an average length of 6 mm, are suitable for the invention.
Preferably, the additive manufacturing process in which a composition as described above is a method of depositing a composition in melted form, also called FDM for the English acronym Fused Deposition Modeling.
FIG. 1 describes a first step of a method of the invention.
In a first step of such a process, a composition as described below above, can be fed into an extruder 1.
In the illustrated embodiment, the extruder 1 can be of the double type screw.
For example, extrusion can be performed between 360 C and 420 C.
The rotation of the screws can be between 50 revolutions per minute and 120 revolutions through minute, and the mixing time can be between 5 min and 30 min.
Date Received / Date Received 2020-04-21

7 The extrusion allows an excellent mixing of the different components of the composition and thus better homogenization of the carbon fibers in the mixture polymeric.
At the end of the extrusion, the composition 2 obtained can be in form of a .. wire with a diameter between 1.50 mm and 1.95 mm.
Figure 2 shows a 3D printer that can allow the manufacture of a object by additive manufacturing from a composition as described below above.
For example, the body of the printer 4 can be supplied by the composition in the form of a wire 3. Such a wire is preferably obtained directly by extrusion of composition 2, as described in relation to Figure 1.
The printer body 4 is connected to a print head 5 which allows the deposition of the composition in the molten state.
For example, the printhead 5 may have a temperature between the room temperature and 450 C.
During the additive manufacturing process according to the invention, the body of the printer 4 can be heated to temperatures between temperature ambient and 200 C.
A temperature higher than the ambient temperature in the body of the the printer allows in particular to reduce delamination and increase the surface adhesion between the composition filaments once these deposited in molten form.
Examples Example 1: Quantities of carbon fibers introduced In a twin screw extruder are introduced a given quantity of polyetheretherketone of the trade name Victrex 90G, and fibers of CF-Zoltek PX35-85 trade name carbon in quantities different, so that several samples with concentrations of fibers different carbon are made.
Date Received / Date Received 2020-04-21

8 The extrusion is carried out at a temperature between 380 C and 420 C with a screw rotation speed of 100 revolutions per minute and a mixing time of minutes.
The polyetheretherketone yarn obtained at the end of the extrusion is introduced in 5 AonM2 commercial reference 3D printer. Printing temperature is of 410 C. A 15 cm filament with a diameter of 0.6 mm is printed and subject to a tensile test carried out on an MTS insight machine and analyzed by a method of image correlation (DIC for the English acronym Digital image correlation).
Table 1 gathers the results of the determination of the Young's modulus got 10 for the different samples made.
[Table 1]
Mass concentration Sample Young's Modulus (GPa) carbon fiber (%) 1 0 2.91 2 30 13.04 3 40 17.88 4 50 13.86 Table 1 first shows that when carbon fibers are present, the mechanical properties are greatly increased compared to polymer alone.
The results also show that optimal conditions are obtained for a carbon fiber concentration of about 40 A.
Finally, it is observed that a mass concentration of 50% of fibers of carbon does not affect the printability of the composition.
Example 2: Polyetheretherketone / polyetherimide ratio Filaments of 15 cm and a diameter of 0.6 mm were synthesized by additive manufacturing with different compositions, under conditions similar to Date Received / Date Received 2020-04-21

9 Example 1. The Young's moduli of the filaments obtained were determined in by a test identical to that of Example 1.
Polyetheretherketone is the product of the trade name Victrex 90G

while the polyetherimide is the Ultem 1010 product.
The results of the characterizations are presented in Table 2.
[Table 2]
Polyetheretherketone Polyetherimide Concentration Young's modulus (% of the mixture (% of the mass mixture of fibers (GPa) polymeric) polymeric) carbon (%) 100 0 0 2.91 30 13.04 90 10 2.9 30 11.88 80 20 0 3.39 30 14.05 70 30 0 2.70 30 11.41 60 40 0 2.82 30 13.99 50 50 0 3.03 30 10.56 40 60 0 3.04 30 10.87 0 100 0 3.59 30 10.07 As in example 1, the addition of carbon fibers always allows the increase Young's modulus of the material obtained by additive manufacturing.
The best mechanical performance is obtained for a mixture polymeric comprising a concentration of polyetheretherketone included Between 60% and 90% and a polyetherimide concentration between 40% and 10 %.
Here again, no difficulty in printing the different compositions, even for mass concentrations of carbon fibers of 30%.
Example 3: Characterization by scanning electron microscopy Date Received / Date Received 2020-04-21

10 Figures 3 and 4 represent photographs obtained by microscopy scanning electronics.
The samples all have a mass concentration of carbon fibers of 30 %
by mass relative to the total mass of the polymer mixture.
Figure 3 is obtained for a polymeric mixture containing 90% of polyetheretherketone and 10% polyetherimide obtained after extrusion.
Figure 4 is obtained for a polymeric mixture containing 70% of polyetheretherketone and 30% polyetherimide obtained after extrusion after 3D printing, under conditions identical to those of example 1.
io Figures 3 and 4 show the good homogeneity of the distribution of fibers carbon in the polymer mixture at all stages of the preparation, thus that good wetting of the polymeric mixture on the carbon fibers.
Example 4: Characterization of the degradation temperature of the compositions Different polymers and polymeric mixtures, loaded with carbon fibers or no were subjected to thermogravimetric analysis.
Figure 5 shows the results of such a thermogravimetric analysis for a polyetheretherketone alone (Victrex90G) 51, a polyetherimide alone (Ultem 1010) 52 and a polyetheretherketone / polyetherimide mixture in a 70/30 mass ratio 53.
Figure 6 shows the results of an analysis similar to that in Figure 5 but for a polyetheretherketone alone (Victrex381G) 61, a polyetherimide alone (Ultem 1010) 62 and a polyetheretherketone / polyetherimide mixture in a ratio mass 70/30 all three loaded with 30% by mass of fibers of carbon (CF-Zoltek PX35-85 carbon fibers).
These two analyzes show on the one hand that the decomposition temperature of polymeric mixture is greater than 500 C and is between that of polyetherimide and that of polyetheretherketone. This temperature is compatible with an application for additive manufacturing, especially since it is higher than the temperatures reached in the print heads.
Date Received / Date Received 2020-04-21

11 On the other hand, the decomposition temperature is little modified by the introduction in the polymeric mixture of carbon fibers, which makes it possible to conclude than the polymeric mixture can be used for additive manufacturing, notably at the temperatures reached in the print heads.
Date Received / Date Received 2020-04-21

Claims

Claims [Claim 1]
Composition for additive manufacturing characterized in that that it understands:
- a polymeric mixture comprising a polyetheretherketone and a polyetherimide, and - carbon fibers.
[Claim 2] Composition for additive manufacturing according to Claim 1 in which the polymeric mixture comprises between 50%
and 90% by mass of polyetheretherketone and between 10% and 50% by mass of polyetherimide relative to the total mass of the polymeric mixture.
[Claim 3]
Composition for additive manufacturing according to one any of claims 1 to 2, wherein the polymeric mixture only includes polyetheretherketone and polyetherimide.
[Claim 4] Composition for additive manufacturing according to one any of claims 1 to 3, wherein the polyetheretherketone has a viscosity of less than 90 Pa.s in the molten state.
[Claim 5]
Composition for additive manufacturing according to one any of claims 1 to 4, wherein the polyetherimide has a viscosity less than about 500 Pa.s at 385 C and a strain rate in shear of 100 s-1.
[Claim 6]
Composition for additive manufacturing according to one any of claims 1 to 5, wherein the mass concentration of carbon fibers is between strictly more than 30% by mass and 50% by mass relative to the total mass of the polymeric mixture.
[Claim 7]
Composition for additive manufacturing according to one any of claims 1 to 6, wherein the carbon fibers have a length varying from 25 microns to 25 mm.
[Claim 8]
Manufacturing process of a part or coating by additive manufacturing comprising at least one step of depositing a composition as defined by any one of claims 1 to 6 in molten form.
Date Received / Date Received 2020-04-21 [Claim 9]
Manufacturing process according to claim 8 comprising, prior to the deposition step, a step of extruding a composition as defined by any one of claims 1 to 6.
[Claim 10]
Manufacturing process according to claim 9 in which extrusion is carried out at a temperature between 360 C and 420 C.
Date Received / Date Received 2020-04-21