Patent Application
20230027920
The present invention relates to polyetherimide (PEI) polymers which can for example be used in lithographic processes for the photofabrication of three-dimensional (3D) articles. The invention further relates to formulations including these polyetherimide polymers. Still further, the invention relates to lithographic methods to form three-dimensional (3D) objects that incorporate the aforementioned polymer formulations.
Polymer compositions are commonly used to manufacture articles for the automotive and aerospace industries, for example as engine parts, as well as in the healthcare industry, for example as implantable devices and dental prostheses. These articles have to present good mechanical properties after fabrication, but they also have to retain a sufficient percentage of these properties over time, notably at their temperature of use (sometimes higher than 150° C.).
Lithographic process for the photofabrication of 3D articles from polymeric materials have found recent popularity due to their relative speed and simplicity. In general, lithographic processes involve the use of light, for example UV irradiation, to locally cure a polymerizable composition at specific locations. The localized curing allows for the fabrication of 3-dimensional articles.
Lithographic processes generally use polymerizable compositions that are liquid in order to obtain parts with a good resolution. Polymerizable compositions that are liquid at room temperature are easier to use in a printing process, but they generally lead to articles having moderate mechanical properties and thermal stability.
Certain polymers present a better mechanical property profile, but they need to be above their melting temperature to be used in lithographic processes. Additionally, these polymers not only need to be reactive in the printing process, when irradiating the layer of polymer, but they also need to be sufficiently thermally stable at temperatures required to melt the polymers.
WO18035368A1 relates to a polymer resin for vat photopolymerization. The polymer resin can include a polyamic diacrylate ester or salt thereof, the polyamic diacrylate ester or salt comprising a plurality of photocrosslinkable groups pendently attached thereto; a photoinitiator suitable for initiating crosslinking of the photocrosslinkable groups when exposed to a light source of a suitable wavelength and intensity; and a suitable organic solvent.
Hegde, et al. “3D printing all-aromatic high-performance polyimides using μSLA: Processing the non-processable” (252nd ACS National Meeting & Exposition, Aug. 21-25, 2016) and Hedge et al. “3D Printing All-Aromatic Polyimides using Mask-Projection Stereolithography: Processing the Nonprocessable” (Adv. Mater. 2017, 29, published on Jun. 19, 2017), disclose 3D printing of a polyamic diacrylate ester (PADE) in which each repeating unit derives from 4,4′-oxydianiline (ODA) and pyromellitic dianhydride, and contains two photo-crosslinkable acrylate groups.
Herzberger et al. “3D Printing All-Aromatic Polyimides Using Stereolithographic 3D Printing of Polyamic Acid Salts” (ACS Macro Lett., 2018, 7 (4), pp 493-497) describes 3D printing of polyamic acid (PAA) structures derived from 4,4′-oxydianiline (ODA) and pyromellitic dianhydride, and containing 2-(dimethylamino)ethyl methacrylate.
There is a need for polymerizable polymers and compositions to be used in lithographic processes which are capable of producing 3D articles that possess good mechanical properties after photofabrication while also retaining their mechanical properties after exposure to high temperature and light, for example above 150° C. There is also a need for polymerizable polymers and compositions well-suited for high temperature 3D printing processes, notably that are thermally stable at temperatures required to melt the polymers. The present invention relates to a polymer that is soluble, photo reactive, and can convert into a thermally stable sulfone following photo reaction via imidization of the linkages.
According to a first aspect, the present invention relates to polyetherimide (PEI) polymers, which can for example be used in lithographic processes for the photofabrication of three-dimensional (3D) articles.
Stereolithography is an additive manufacturing process that works by focusing light, for example an ultraviolet (UV) light or visible light, on a vat of crosslinkable photopolymer resin. Then complex three-dimensional (3D) structures can be built in a layer-by-layer fashion.
The PEI polymer of the invention can be 3D printed to manufacture articles, for example using the stereolithography technology (SLA), the ink-jet technology, direct ink writing (DIW) or digital light processing (DLP).
The PEI polymer of the present invention may notably be liquid, in the form of a powder or pellets.
Since the PEI polymer notably contains PEI recurring units, the printed material has been shown to exhibit properties, notably mechanical properties, similar to PEI polymers as such.
The polyetherimide (PEI) polymer (P1) also comprises at least one group of formula (L1) to (L4):
in which Ar and Ar′ are respectively trivalent or tetravalent aromatic moiety selected from the group consisting of a substituted or unsubstituted, saturated, unsaturated or aromatic monocyclic and polycyclic group having 5 to 50 carbon atoms, and in which Z is a group which may optionally be removed during the 3D printing process or after printing as a post-printing step involving thermo-curing.
The PEI polymer (P1) of the invention is such that, in formulas (L1) and (L2) above, each Z is independently selected from the group consisting of:
In some embodiments, the PEI polymer (P1) is such that Z is O—(CH2)k—O—CO—CH═CHR4, with k is between 2 and 6, preferably equal to 2 or 3, and R4 is H or CH3.
The PEI polymer (P1) may preferably have a number average molecular weight (Mn) (as measured by gel permeation chromatography (GPC) using N,N-dimethylformamide as a mobile phase, with polystyrene standards) of:
According to an embodiment, the PEI polymer (P1) of the present invention has a Tg ranging from 120 and 250° C., preferably from 170 and 240° C., more preferably from 180 and 230° C., as measured by differential scanning calorimetry (DSC) according to ASTM D3418.
According to a second aspect of the present invention, the PEI polymer (P1) described above may be incorporated in a formulation (F) to be used in photofabrication processes. In particular, the polymer (P1) and formulation (F) of the present invention can be incorporated into lithographic processes in which light is used to cure or crosslink the functionalized polymers.
The formulation (F) of the present invention also comprises:
The formulation (F) of the present invention is preferably liquid, for example at room temperature or above.
The formulation (F) can have a large viscosity range, which depends on the type of 3D printing method used. For example the viscosity of the formulation (F) may vary between 0.01 and 10,000 Pa·s. The viscosity of the formulation (F) preferably ranges between 0.01 and 10 Pa·s when the object is printed via stereolithography (SLA). The viscosity of the formulation (F) preferably ranges between 10 and 10,000 Pa·s when the object is printed via direct ink writing (DIW). The viscosity of the formulation (F) is preferably less than 0.1 Pa·s when the object is printed via ink-jetting.
According to the present invention, a photoinitiator is a compound especially added to a formulation to convert absorbed light energy, UV or visible light, into chemical energy in the form of initiating species, for example free radicals or cations.
According to the present invention, a blocker is a compound added to either scavenge unused radicals created by the photoinitiator or absorb a portion of the incident light energy, for example UV light and visible light. This compound allows for improving dimensional accuracy of the fabricated part.
The formulation (F) of the present invention can comprise more than one polymer (P1), for example two of three distinct polymers (P1).
Polyetherimide (PEI) Polymer
The polyetherimide (PEI) polymer (P1) of the present invention comprises recurring units RPEI according to formula (M):
wherein R and T are as follows
—O— or —O-Q-O—
According to an embodiment of the present disclosure, Q is of the general formula (IX), as detailed above. For example, Q is of formula (X):
According to an embodiment of the present disclosure, at least 50 mol. %, at least 60 mol. %, at least 70 mol. %, at least 80 mol. %, at least 90 mol. %, at least 95 mol. %, at least 99 mol. % or all of the recurring units in the PEI (P1) are recurring units (RPEI) of formulas (M).
According to an embodiment, the polyetherimide (PEI) polymer (P1) of the present invention comprises recurring units (RPEI) of formulas (M1) or (M2), in imide forms, or their corresponding amic acid forms and mixtures thereof:
In a preferred embodiment of the present invention, at least 50 mol. %, at least 60 mol. %, at least 70 mol. %, at least 80 mol. %, at least 90 mol. %, at least 95 mol. %, at least 99 mol. % or all of the recurring units in the PEI (P1) are recurring units (RPEI) of formulas (M1) or (M2), in imide forms, or their corresponding amic acid forms and mixtures thereof.
Such aromatic polyimides are notably commercially available from Sabic Innovative Plastics as ULTEM® polyetherimides.
Solvent
The concentration of the solvent may be between 1 to 80 wt. %, based on the total weight of the formulation (F), for example between 2 and 75 wt. %, between 5 and 70 wt. % or between 10 and 65 wt. %.
According to an embodiment of the present invention, the solvent is selected from the group consisting of ortho-dichlorbenzene 1,2 dichloroethane, m-cresol, chlorobenzene, chloroform, N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), 1,3-dimethyl-2-imidazolidinone, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO) and sulfolane, and γ-butyrolactone and γ-valerolactone
Preferably, the solvent is a dipolar aprotic solvent. Preferably, the solvent is selected from the group consisting of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc or DMA), N-Cyclohexyl-2-pyrrolidone (CHP) and dimethyl sulfoxide (DMSO), and γ-butyrolactone and γ-valerolactone
Photoinitiator
According to the present invention, the photoinitiator is a compound especially added to a formulation to convert absorbed light energy such as UV or visible light, into chemical energy in the form of initiating species, for example free radicals or cations. Based on the mechanism by which initiating radicals are formed, photoinitiators are generally divided into two classes:
The concentration of the photoinitiator in the formulation (F) may be between 0.01 to 10 wt. %, based on the total weight of the formulation (F), for example between 0.1 and 5 wt. %, between 0.2 and 4 wt. %, or between 0.5 and 3 wt. %.
According to an embodiment of the present invention, the photoinitiator is selected from the group consisting of:
mixture thereof. Preferably, the photoinitiator is selected from the group consisting of 2,2-dimethoxy-2-phenylacetophenone (DMPA), Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.
Blocker
According to the present invention, a blocker is a compound that is added to the formulation in order to (i) scavenge a predetermined amount of radicals formed by the photoinitiator while irradiated by light, (ii) scavenge unused radicals that may be present after the light irradiation source has been turned off, and/or (iii) absorb a portion of the energy that is delivered to the system during light irradiation.
The concentration of the blocker in the formulation (F) may be between 0.05 to 10 wt. %, based on the total weight of the formulation (F), for example between 0.1 and 5 wt. %, between 0.2 and 4 wt. % or between 0.5 and 3 wt. %.
According to an embodiment of the present invention, the blocker is selected from the group consisting of:
Preferably, the blocker is selected from the group consisting of avobenzone and 2,5-Bis(5-tert-butyl-benzoxazol-2-yl)thiophene.
Optional Components
The formulation of the present invention may comprise at least one additive, for example selected from the group consisting of fillers such as silica, antioxidants, antibacterial compounds and antistatic compounds. The additive may for example be a chemically inert species such as carbon black, silica (e.g. microsilica particles) and carbon nano tubes.
According to a third aspect of the present invention, the PEI polymer (P1) described above may be incorporated in a composition (C).
The composition (C) may comprise the PEI polymer (P1) in an amount of at least 1 wt. %, for example at least 5 wt. %, at least 10 wt. %, at least 15 wt. %, at least 20 wt. %, at least 25 wt. %, or at least 30 wt. %, based on the total weight of the composition (C).
The composition (C) may comprise the PEI polymer (P1) in an amount of more than 50 wt. %, for example more than 55 wt. %, more than 60 wt. %, more than 65 wt. %, more than 70 wt. %, more than 75 wt. %, more than 80 wt. %, more than 85 wt. %, more than 90 wt. %, more than 95 wt. % or more than 99 wt. %, based on the total weight of the composition (C).
According to an embodiment, the composition (C) comprises the PEI polymer (P1) in an amount ranging from 1 to 99 wt. %, for example from 3 to 96 wt. %, from 6 to 92 wt. % or from 12 to 88 wt. %, based on the total weight of the composition (C).
The composition (C) may further optionally comprise one or more additional additives selected from the group consisting of light stabilizers (for example UV light stabilizers), photosensitizers, heat stabilizers, acid scavengers (i.e. zinc oxide, magnesium oxide), antioxidants, pigments, processing aids, lubricants, flame retardants, and/or conductivity additive (i.e. carbon black and carbon nanofibrils).
The composition (C) may also further comprise other polymers than the PEI polymer (P1) of the present invention, for example sulfone polymer, e.g. poly(biphenyl ether sulfone) (PPSU), polysulfone (PSU), polyethersulfone (PES), or a polyphenylene sulfide (PPS), a poly(aryl ether ketone) (PAEK), e.g. a poly(ether ether ketone) (PEEK), a polyamide-imide (PAI), a polyimide (PI), a polyphenylene (SRP), a poly(ether ketone ketone) (PEKK), a poly(ether ketone) (PEK) or a copolymer of PEEK and poly(diphenyl ether ketone) (PEEK-PEDEK copolymer), another polyetherimide polymer (PEI), and/or polycarbonate (PC).
The composition (C) may further comprise flame retardants such as halogen and halogen free flame retardants.
The composition (C) may comprise glass fibers, for example E-glass fibers or high modulus glass fibers having an elastic modulus (also called tensile modulus of elasticity) of at least 76, preferably at least 78, more preferably at least 80, and most preferably at least 82 GPa as measured according to ASTM D2343. The composition (C) may also comprise high modulus glass fibers selected from the group consisting of R, S and T glass fibers, for example in an amount of at least 5 wt. %, for example at least 10 wt. %, at least 15 wt. %, at least 20 wt. %, at least 25 wt. %, at least 26 wt. %, or at least 28 wt. %, based on the total weight of the composition (C). The composition (C) may comprise circular cross-section glass fibers and/or non-circular cross-section glass fibers (e.g. flat, rectangular, cocoon-shaped glass fibers).
The composition (C) may comprise carbon fibers, graphene or carbon nanotubes.
The composition (C) can be made by methods well known to the person skilled in the art. For example, such methods include, but are not limited to, melt-mixing processes. Melt-mixing processes are typically carried out by heating the polymer components above the melting temperature of the thermoplastic polymers thereby forming a melt of the thermoplastic polymers. In some embodiments, the processing temperature ranges from about 280-450° C., preferably from about 290-400° C., from about 300-360° C. or from about 310-340° C. Suitable melt-mixing apparatus are, for example, kneaders, Bradbury mixers, single-screw extruders, and twin-screw extruders. Preferably, use is made of an extruder fitted with means for dosing all the desired components to the extruder, either to the extruder's throat or to the melt. The components of the polymer composition are fed to the melt-mixing apparatus and melt-mixed in that apparatus. The components may be fed simultaneously as a powder mixture or granule mixer, also known as dry-blend, or may be fed separately.
According to a fourth aspect, the present invention also relates to a process for preparing the PEI polymer (P1) of the present invention.
According to a first embodiment, the process for preparing the PEI polymer (P1) comprises at least the following two steps:
a) providing a PEI polymer (P0) of formula RnRmN—P—NRnRm, wherein P comprises recurring units RPEI, as above described, and each Rn and Rm is independently H or an alkyl, preferably H or an alkyl having 1 to 5 carbon atoms;
b) reacting the PEI polymer (P0) with a compound of any one of formulas (I) to (IV):
wherein:
The polymer PEI (P0) is according to formula RnRmN—P—NRnRm. Preferably, Rn and Rm are H and P0 is according to formula H2N—P—NH2.
In embodiments wherein the amine moieties (NRnRm or NH2) are link to the polymer P via a phenylene group (C6H6), the amine moieties may be in position ortho (1,2-aminophenyl), meta (1,3-aminophenyl), or para (1,4-aminophenyl) with respect to the polymer chain P, preferably in position para (1,4-aminophenyl) with respect to the carbon chain P.
According to an embodiment, the polar aprotic solvent is selected from the group consisting of chlorobenzene, chloroform, N-methylpyrrolidone (NMP), N,Ndimethylformamide (DMF), N,N-dimethylacetamide (DMAC), 1,3-dimethyl-2-imidazolidinone, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO) and sulfolane.
According to an embodiment, the organic base is selected from the group consisting of pyridine and alkylamine, for example trimethylamine.
According to a second embodiment, the process for preparing the PEI polymer (P1) comprises at least the following three steps:
a) providing a PEI polymer (P0) of formula RnRmN—P—NRnRm, wherein P comprises recurring units RPEI, wherein
as above described, and each Rn and Rm is independently H or an alkyl, preferably H or an alkyl having 1 to 5 carbon atoms;
b) reacting the PEI polymer (P0) with a compound of any one of formulas (V), to (VIII):
wherein:
According to a fifth aspect, the present invention also relates to a method for manufacturing a 3D article with an additive manufacturing system, comprising:
According to an embodiment, the step of printing comprises irradiating the polymer formulation (F), for example a layer of such formulation (F) deposited onto the printing surface, with light. For example, with UV light, the layer preferably presents a size in the range of 5 μm to 300 μm, for example 20 μm to 150 μm.
The light source can for example be laser light. The irradiation is preferably of sufficient intensity to cause substantial curing of the polymer formulation (F), for example the layer of such formulation (F). Also, the irradiation is preferably of sufficient intensity to cause adhesion of the layers of polymer formulation (F).
According to another embodiment of the present invention, the method for manufacturing a 3D article with an additive manufacturing system, comprises the steps of:
According to an embodiment, the polymer formulation (F) is at room temperature during the process. Alternatively, the formulation can be heated before and/or during printing, especially if the polymer concentration in the formulation is high. In this case, the temperature can be heated up to 130° C., up to 120° C. or up to 110° C. before and/or during printing.
The present invention also relates to the use of the polymer (P1) of the present invention or of the polymer formulation (F) of the present invention, for the manufacture of 3D objects/articles.
All of the embodiments described above with respect to the polymer (P1) and the polymer formulation (F) do apply equally to the use for the manufacture of 3D objects/articles.
The present invention also relates to 3D objects or 3D articles obtainable, at least in part, from the method of manufacture of the present invention, using the polymer (P1) or the polymer formulation (F) herein described.
The 3D objects or articles obtainable by such method of manufacture can be used in a variety of final applications. Mention can be made in particular of implantable device, dental prostheses, brackets and complex shaped parts in the aerospace industry and under-the-hood parts in the automotive industry.
Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.
The invention will be now described in more detail with reference to the following examples whose purpose is merely illustrative and not limitative of the scope of the invention.
A PEI polymer (P1) and corresponding PEI polymer (P2) according to the present invention were prepared and characterized.
Molecular Weight (Mn, Mw, Mz and Mz+1)
The molecular weights were measured by gel permeation chromatography (GPC), using N,N-dimethylformamide as a mobile phase. Two 5μ mixed D columns with guard column from Agilent Technologies were used for separation. An ultraviolet detector of 254 nm was used to obtain the chromatogram. A flow rate of 1.5 ml/min and injection volume of 20 μL of a 0.2 w/v % solution in mobile phase was selected. Calibration was performed with 12 narrow molecular weight polystyrene standards (Peak molecular weight range: 371,000 to 580 g/mol). The number average molecular weight Mn, weight average molecular weight Mw, higher average molecular weight Mz and Mz+1, were reported.
This example demonstrates the synthesis of a polymer (P1-A), comprising recurring units RPEI according to Scheme 1.
Formation of the Reactants Amine-PEI and PDMA-HEA (I-A)
The Amine-PEI (polymer P0-A) was synthetized as follows:
In a 100-mL 3-neck flask (equipped with a mechanical stirrer, a Dean-Stark trap wrapped in heat tape at 110° C., a condenser (above the dean-Stark trap), and a nitrogen gas inlet/outlet, and external thermocouple with oil bath), 1,3-bis[N-(4-chlorophthalimido)]benzene (11.0841 g), 4,4′-biphenol (5.2290 g), m-aminophenol (0.4685 g), and K2CO3 (3.6825 g) were suspended in mixture of NMP (22.29 g), toluene (13.66 g) and sulfolane (60.21 g) for a 19.5 wt % solids solution. The mixture was heated for 1 h at 140° C. and then heated for 10 h at 210° C. with stirring (160 rpm) and medium nitrogen flow. The solution was cooled to 60° C. the solution was coagulated in a blender containing 500 mL of de-ionized water which gave rise to a grey precipitate. The solid material collected was then repeatedly washed with hot H2O (3×500 mL), filtered, and then washed with methanol (3×500 mL). The final solid material collected via filtration was then dried in a vacuum oven (45° C., 25 inHg) for 72 h to yield 11.54 g of a light grey solid.
The PDMA-HEA diacid chloride (I-A) (PMDA-HEA-Cl, Mw: 455.24 g/mol) was synthesized according to methods reported in the literature. Reference can be made in particular to Hedge et al. “3D Printing All-Aromatic Polyimides using Mask-Projection Stereolithography: Processing the Nonprocessable” (Adv. Mater. 2017, 29).
Formation of the PEI Polymer (P1-A)
A three-neck flask equipped with a gas-inlet, magnetic stir bar and thermocouple was charged with 2.3195 g of Amine-PEI, 0.1 mL of pyridine and 10.5 mL dry NMP. To the flask, 0.2036 g PMDA-HEA (I-A) was then added as single portion and then left stirring at room temperature for 4 h. After mixing the solution was coagulated into 500 mL MeOH and washed MeOH (500 mL×3) with heavy agitation with each wash. The precipitant was collected under vacuum filtration and dried under reduced pressure (25 inHg) at 25° C. for 48 h. Yield 2.4456 g
This example demonstrates the synthesis of a PEI polymer (P2-A), according to Scheme 2.
A tube furnace was charged 506.7 mg of polymer P1-A and was purged for 20 min under a flow of N2. A flow of N2 kept until the sample was taken out of the furnace. After the purge, the tube was then heated at 250° C. for 17 min. After heating, the tube was allowed to cool to room temperature (˜1.5 h) and the sample was removed from the furnace.
The different polymers were characterized by GPC to determine molecular weights (Mn & Mw) and polydispersity index (PDI). The results are summarized in Table 1.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20165233.6 | Mar 2020 | EP | regional |
This application claims priority to U.S provisional application U.S. 62/938,508 filed on Nov. 21, 2019 and to European patent application 20165233.6 filed on Mar. 24, 2020, the whole content of these applications being incorporated herein by reference for all purposes.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/082644 | 11/19/2020 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62938508 | Nov 2019 | US |
