Patent Description:
The strength of additive manufactured articles, especially tensile strength in the z direction, i.e., the direction in which layers are added during the additive manufactured, can be affected by poor interlayer adhesion, which can limit the applications of the additive manufactured articles. Additive manufactured articles can also suffer from high part warpage, especially additive manufactured articles printed with semicrystalline polymers, which can provide chemical resistance.

<CIT> relates to 3D printer inputs including filaments comprising separated layers or sections. The inputs including filaments may be prepared by coextrusion, microlayer coextrusion or multicomponent/fractal coextrusion. The inputs and filaments may enable layering or combining different materials simultaneously through one or more nozzles during the so-called 3D printing process. The techniques may facilitate smaller layer sizes (milli, micro, and nano) different layer configurations as well as the potential to incorporate materials that would otherwise not be usable in standard 3D printer methods.

<CIT> discloses a polycarbonate/polybutylene terephthalate (PC/PBT) composite material. Glass fiber and nano carbon fiber in the composite material allegedly have synergetic strengthening and toughening functions.

<CIT> is directed to a composition comprising a polyester, polycarbonate, organopolysiloxane-polycarbonate block copolymer, organophosphorus flame retardant, fluorinated polyolefin, and one or more additives. In particular, a thermoplastic composition comprises, based on the total weight of the composition: (a) from more than <NUM> to <NUM> wt. % of a polyester; (b) from <NUM> to <NUM> wt. % of a polycarbonate; (c) from <NUM> to less than <NUM> wt. % of an organopolysiloxane-polycarbonate block copolymer comprising from <NUM> to <NUM> wt. % of polydiorganosiloxane units; (d) from <NUM> to <NUM> wt. % of an organophosphorus flame retardant; (e) from <NUM> to <NUM> wt. % of a fluorinated polyolefin; (f) optionally, from <NUM> to <NUM> wt. % of an impact modifier selected from the group consisting of elastomer-based graft copolymers and elastomer-based block copolymers; and (g) from <NUM> to <NUM> wt. % of an additive composition comprising an antioxidant, a quencher, an ultraviolet light stabilizer, or a combination thereof.

It would be desirable to provide additive manufactured articles with improved strength in the z direction.

Disclosed herein are compositions and articles made therefrom.

According to claim <NUM>, the composition comprises, based on a total weight of the composition: <NUM> to <NUM> wt% of polycarbonate; <NUM> to <NUM> wt% of polybutylene terephthalate; <NUM> to <NUM> wt% of carbon fiber; <NUM> to <NUM> wt% of an ethylene acrylic ester terpolymer; and less than <NUM> wt% of glass fiber; wherein the total weight of the composition is <NUM> wt%.

The following figures are exemplary embodiments.

This disclosure relates to additive manufactured articles, e.g., articles made from thermoplastic compositions according to claim <NUM>, said compositions containing polycarbonate (PC), polybutylene terephthalate (PBT), carbon fibers (CF), an ethylene acrylic ester terpolymer (hereinafter "terpolymer"), and optionally additives (such as compatibilizers, stabilizers, and minerals). This composition enables the production of additive manufactured articles with improved warp and chemical resistance.

A synergistic effect has been discovered when using the compositions containing polycarbonate, polybutylene terephthalate, carbon fibers, and the terpolymer (hereinafter "the PC/PBT/CF/terpolymer composition"), for additive manufacturing. Namely, the use of the composition to form an additive manufactured article (also referred to herein as a printed article) improves z direction strength. This was particularly surprising as the effect is not attained when using this composition to form an injection molded article.

The printed articles containing the PC/PBT/CF/terpolymer composition also provide desirable chemical resistance and low warpage. The printed articles can exhibit z direction tensile strength of at least <NUM> megapascals (MPa), preferably at least <NUM> MPa, as determined by a modified ASTM D <NUM> test method.

Dicarboxylic acids (e.g., aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, aromatic dicarboxylic acids, and combinations thereof) and diols (e.g., aliphatic diols, alicyclic diols, aromatic diols, and combinations thereof) can be used to prepare polyester, such as the PBT. As used herein, polybutylene terephthalate can be used interchangeably with poly(l,<NUM>-butylene terephthalate). Chemical equivalents of dicarboxylic acids (e.g., anhydrides, acid chlorides, acid bromides, carboxylate salts, or esters) and chemical equivalents of diols (e.g., esters, preferably C<NUM>-C<NUM> esters such as acetate esters) may also be used to prepare the PBT.

Aromatic dicarboxylic acids that can be used to prepare the polyesters include, but are not limited to, isophthalic acid, terephthalic acid, <NUM>,<NUM>-di(p-carboxyphenyl)ethane, <NUM>,<NUM>'-dicarboxydiphenyl ether, <NUM>,<NUM>'-bisbenzoic acid, and the like, and <NUM>,<NUM>- or <NUM>,<NUM>-naphthalene dicarboxylic acids and the like. A combination of isophthalic acid and terephthalic acid can be used. The weight ratio of isophthalic acid to terephthalic acid may be, for example, <NUM>:<NUM> to <NUM>:<NUM>, or <NUM>:<NUM> to <NUM>:<NUM>. Dicarboxylic acids containing fused rings that can be used to prepare the polyesters include, but are not limited to, <NUM>,<NUM>-, <NUM>,<NUM>-, and <NUM>,<NUM>-naphthalenedicarboxylic acids. Exemplary cycloaliphatic dicarboxylic acids include, but are not limited to, decahydronaphthalene dicarboxylic acids, norbornene dicarboxylic acids, bicyclooctane dicarboxylic acids, and <NUM>,<NUM>-cyclohexanedicarboxylic acids.

Aliphatic diols that can be used to prepare the polyesters include, but are not limited to, <NUM>,<NUM>-ethylene glycol, <NUM>,<NUM>- and <NUM>,<NUM>-propylene glycol, <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-propane diol, <NUM>-ethyl-<NUM>-methyl-<NUM>,<NUM>-propane diol, <NUM>,<NUM>- and <NUM>,<NUM>-pentane diol, dipropylene glycol, <NUM>-methyl-<NUM>,<NUM>-pentane diol, <NUM>,<NUM>-hexane diol, dimethanol decalin, dimethanol bicyclooctane, <NUM>,<NUM>-cyclohexane dimethanol and its cis- and trans-isomers, triethylene glycol, <NUM>,<NUM>-decane diol, and the like, and combinations thereof. The diol may be ethylene or <NUM>,<NUM>-butylene diol. The diol may be <NUM>,<NUM>-butylene diol. The diol may be ethylene glycol with small amounts (e.g., <NUM> to <NUM> percent) of diethylene glycol. Aromatic diols that can be used to prepare the polyesters include, but are not limited to, resorcinol, hydroquinone, pyrocatechol, <NUM>,<NUM>-naphthalene diol, <NUM>,<NUM>-naphthalene diol, <NUM>,<NUM>-naphthalene diol, <NUM>,<NUM>'-dihydroxybiphenyl, bis(<NUM>-hydroxyphenyl)ether, bis(<NUM>-hydroxyphenyl)sulfone, and the like, and combinations thereof.

In some embodiments, the PBT that is obtained by polymerizing a glycol component comprising at least <NUM> mole percent, preferably at least <NUM> mole percent, of tetramethylene glycol (<NUM>,<NUM>-butanediol), and an acid component comprising at least <NUM> mole percent, preferably at least <NUM> mole percent, of terephthalic acid or polyester-forming derivatives thereof. Commercial examples of PBT include those available as VALOX™ <NUM> Resin and VALOX™ <NUM> Resin, manufactured by SABIC.

In some embodiments, the PBT comprises a modified PBT, that is, a PBT derived in part from PET, for example recycled PET from used soft drink bottles. The PET-derived PBT polyester (referred to herein for convenience as a "modified PBT") can be derived from a PET component such as PET, a PET copolymer, or a combination thereof. The modified PBT can further be derived from biomass-derived <NUM>,<NUM>-butanediol, e.g., corn-derived <NUM>,<NUM>-butanediol or a <NUM>,<NUM>-butanediol derived from a cellulosic material. Unlike conventional molding compositions containing virgin PBT (PBT that is derived from <NUM>,<NUM>-butanediol and terephthalic acid monomers), the modified PBT contains units derived from ethylene glycol and isophthalic acid. Use of modified PBT can provide a valuable way to effectively use underutilized scrap PET (from post-consumer or post-industrial streams) in PBT thermoplastic molding compositions, thereby conserving non-renewable resources and reducing the formation of greenhouse gases, e.g., carbon dioxide.

The modified PBT can have at least one residue derived from the PET component. Such residue can be selected from the group consisting of ethylene glycol residues, diethylene glycol residues, isophthalic acid residues, antimony-containing residues, germanium-containing residues, titanium-containing residues, cobalt-containing residues, tin-containing residues, aluminum, aluminum-containing residues, <NUM>,<NUM>-cyclohexane dimethanol residues, <NUM>,<NUM>-cyclohexane dimethanol residues, alkali salts and alkaline earth metal salts including calcium and magnesium and sodium and potassium salts, phosphorous-containing residues, sulfur-containing residues, naphthalene dicarboxylic acid residues, <NUM>,<NUM>-propanediol residues, and combinations thereof.

"Polycarbonate" as used herein means a homopolymer or copolymer having repeating structural carbonate units of the formula (<NUM>)
<CHM>
wherein at least <NUM> percent of the total number of R<NUM> groups are aromatic, or each R<NUM> contains at least one C<NUM>-<NUM> aromatic group. Polycarbonates and their methods of manufacture are known in the art, being described, for example, in <CIT>, <CIT>, and <CIT>. Polycarbonates are generally manufactured from bisphenol compounds such as <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl) propane ("bisphenol-A" or "BPA"), <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl) phthalimidine, <NUM>,<NUM>-bis(<NUM>-hydroxy-<NUM>-methylphenyl)cyclohexane, or <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)-<NUM>,<NUM>,<NUM>-trimethylcyclohexane (isophorone), or a combination comprising at least one of the foregoing bisphenol compounds can also be used. In a specific embodiment, the polycarbonate is a homopolymer derived from BPA; a copolymer derived from BPA and another bisphenol or dihydroxy aromatic compound such as resorcinol; or a copolymer derived from BPA and optionally another bisphenol or dihydroxyaromatic compound, and further comprising non-carbonate units, for example aromatic ester units such as resorcinol terephthalate or isophthalate, aromatic-aliphatic ester units based on C<NUM>-<NUM> aliphatic diacids, polysiloxane units such as polydimethylsiloxane units, or a combination comprising at least one of the foregoing.

The polycarbonate is present in the composition in an amount of <NUM> to <NUM> weight percent (wt%), for example, <NUM> to <NUM> wt%, preferably <NUM> to <NUM> wt%. The polycarbonate can have an intrinsic viscosity, as determined in chloroform at <NUM> of about <NUM> to about <NUM> dl/g, preferably about <NUM> to about <NUM> dl/g. The polycarbonate can be branched or unbranched. In an embodiment, the polycarbonate is a linear polycarbonate. The polycarbonate can have a weight average molecular weight of about <NUM>,<NUM> to about <NUM>,<NUM> Daltons, preferably about <NUM>,<NUM> to about <NUM>,<NUM> Daltons as measured by gel permeation chromatography, using a crosslinked styrene-divinylbenzene column and calibrated to bisphenol A homopolycarbonate references.

The polycarbonate can be BPA polycarbonate commercially available under the trade designation LEXAN™ from SABIC, such as LEXAN™ <NUM> polycarbonate. For example, the polycarbonate can have a number average molecular weight of <NUM>,<NUM> to about <NUM>,<NUM> Daltons, for example, about <NUM>,<NUM>, and a weight average molecular weight of <NUM>,<NUM> to about <NUM>,<NUM> Daltons, for example, about <NUM>,<NUM> Daltons.

The carbon fiber is present in the composition in an amount of <NUM> to <NUM> wt%, for example, <NUM> to <NUM> wt%, preferably <NUM> to <NUM> wt%, based on the total weight of the composition. Carbon fibers can be classified according to their diameter, morphology, and degree of graphitization (morphology and degree of graphitization being interrelated). Carbon fibers can be produced, for example, by pyrolysis of organic precursors in fibrous form, including phenolics, polyacrylonitrile (PAN), or pitch.

The carbon fibers can have a diameter of at least <NUM> micrometers to <NUM> micrometers, preferably <NUM> micrometers to <NUM> micrometers, <NUM> micrometers to <NUM> micrometers, or <NUM> micrometers to <NUM> micrometers. The carbon fibers can have a length of <NUM> millimeters (mm) to <NUM> millimeters, preferably <NUM> micrometers to <NUM> micrometers, or <NUM> millimeters to <NUM> millimeter. The carbon fibers can have a tensile modulus of <NUM> to <NUM> megapounds per square inch (<NUM> to <NUM> gigapascals (GPa)), preferably <NUM> to <NUM> megapounds per square inch (<NUM> to <NUM> gigapascals), more preferably <NUM> to <NUM> megapounds per square inch (<NUM> to <NUM> gigapascals). The carbon fibers can have a tensile strength of <NUM> to <NUM>,<NUM> kilopounds per square inch (<NUM>,<NUM> to <NUM>,<NUM> MPa), preferably <NUM> to <NUM>,<NUM> kilopounds per square inch (<NUM>,<NUM> to <NUM>,<NUM> MPa), more preferably <NUM> to <NUM> kilopounds per square inch (<NUM>,<NUM> to <NUM>,<NUM> MPa).

The ethylene acrylic ester terpolymers can include various acrylic esters (e.g., methyl, ethyl, or butyl acrylate) and third monomers (e.g., maleic anhydride (MAH) or glycidyl methacrylate (GMA)). For example, the following are structures of random ethylene vinyl acetate-maleic anhydride terpolymers obtained by high pressure radical polymerization.

Ethylene acrylic ester terpolymers can be characterized by a reactivity, crystallinity, and fluidity. Ethylene-vinyl acetate can react with other functional polymers to create chemical bonds, which can increase adhesion properties, heat resistance, or long term aging properties, for example, due to the presence of glycidyl methacrylate or maleic anhydride groups. Acrylic ester can decrease the crystallinity of the polymer. Acrylic ester can also help maintain desirable mechanical properties. Acrylic ester additionally can provide excellent thermal stability with limited viscosity change and discoloration (when formulated with a suitable antioxidant). Maleic anhydride can increase adhesion to polar substrates and can allow the creation of chemical bonds onto substrates such as, for example, metal, polymers, metallized products, cellulosic substrates, and rubber.

With specific reference to a random terpolymer of ethylene, acrylic ester, and glycidyl methacrylate, the acrylic ester may provide softness and polarity and may lead to high flexibility (low crystallinity) and high impact absorption behavior, while the glycidyl methacrylate may provide reactivity, leading to desirable dispersion during melt mixing with thermoplastics. An exemplary ethylene acrylic ester glycidyl methacrylate terpolymer is LOTADER™ AX8900, and an exemplary ethylene acrylic ester maleic anhydride terpolymer is LOTADER™ <NUM>, both from Arkema. The terpolymer is present in the composition in an amount of <NUM> to <NUM> wt%, preferably <NUM> to <NUM> wt%, more preferably <NUM> to <NUM> wt%, and more preferably <NUM> to <NUM> wt%, based on the total weight of the composition.

The composition can optionally further include additive(s), such as compatibilizer (e.g., an epoxy chain extender or an epoxy), mold release agent, process stabilizer (e.g., antioxidant, heat stabilizer, light stabilizer), plasticizer, flame retardant, lubricant, antistatic agent, colorant (e.g., a dye or pigment), radiation stabilizer, anti-drip agent (e.g., a polytetrafluoroethylene (PTFE)-encapsulated styrene-acrylonitrile copolymer (TSAN)), or a combination comprising one or more of the foregoing. For example, a combination of a heat stabilizer and ultraviolet light stabilizer can be used.

Examples of mold release agents include both aliphatic and aromatic carboxylic acids and their alkyl esters, for example, stearic acid, behenic acid, pentaerythritol tetrastearate, glycerin tristearate, and ethylene glycol distearate. Polyolefins such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene, and similar polyolefin homopolymers and copolymers can also be used a mold release agents. Some compositions use pentaerythritol tetrastearate, glycerol monosterate, a wax, or a poly alpha olefin. The mold release agent can be pentaerythrityl tetrastearate.

Heat stabilizer additives include organophosphites (e.g., triphenyl phosphite, tris-(<NUM>,<NUM>-dimethylphenyl)phosphite, tris-(mixed mono-and dinonylphenyl)phosphite or the like), phosphonates (e.g., dimethylbenzene phosphonate or the like), phosphates (e.g., trimethyl phosphate, or the like), or combinations comprising at least one of the foregoing heat stabilizers. The heat stabilizer can be tris(<NUM>,<NUM>-di-t-butylphenyl) phosphate.

Light stabilizers include hydroxybenzophenones (e.g., <NUM>-hydroxy-<NUM>-n-octoxy benzophenone), hydroxybenzotriazines, cyanoacrylates, oxanilides, benzoxazinones (e.g., <NUM>,<NUM>'-(<NUM>,<NUM>-phenylene)bis(<NUM>-<NUM>,<NUM>-benzoxazin-<NUM>-one, commercially available under the trade name CYASORB UV-<NUM> from Cytec), aryl salicylates, hydroxybenzotriazoles (e.g., <NUM>-(<NUM>-hydroxy-<NUM>-methylphenyl)benzotriazole, <NUM>-(<NUM>-hydroxy-<NUM>-tert-octylphenyl)benzotriazole, and <NUM>-(<NUM>-benzotriazol-<NUM>-yl)-<NUM>-(<NUM>,<NUM>,<NUM>,<NUM>-tetramethylbutyl)-phenol, commercially available under the trade name CYASORB <NUM> from Cytec) or combinations comprising at least one of the foregoing light stabilizers.

Antioxidant additives include organophosphites such as tris(nonylphenyl)phosphite, tris(<NUM>,<NUM>-di-t-butylphenyl)phosphite, bis(<NUM>,<NUM>-di-t-butylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite; alkylated monophenols or polyphenols; alkylated reaction products of polyphenols with dienes, such as tetrakis[methylene(<NUM>,<NUM>-di-tert- butyl-<NUM>-hydroxyhydrocinnamate)] methane; butylated reaction products of para-cresol or dicyclopentadiene; alkylated hydroquinones; hydroxylated thiodiphenyl ethers; alkylidene- bisphenols; benzyl compounds; esters of beta-(<NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxyphenyl)-propionic acid with monohydric or polyhydric alcohols; esters of beta-(<NUM>-tert-butyl-<NUM>-hydroxy-<NUM>-methylphenyl)- propionic acid with monohydric or polyhydric alcohols; esters of thioalkyl or thioaryl compounds such as distearylthiopropionate, dilaurylthiopropionate, ditridecylthiodipropionate, octadecyl-<NUM>-(<NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxyphenyl)propionate, pentaerythrityl-tetrakis[<NUM>-(<NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxyphenyl)propionate; amides of beta-(<NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxyphenyl)- propionic acid, or combinations comprising at least one of the foregoing antioxidants. The process stabilizer in the form of an antioxidant can be <NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxy-hydrocinnamic acid, tetraester with pentaerythritol (Chemical Abstract Registry No. <NUM>-<NUM>-<NUM>), IRGANOX™ <NUM> from Ciba-Geigy.

The article can be manufactured with an additive manufacturing process. Additive manufacturing processes, or three dimensional (<NUM>-D) printing, are generally defined as processes that build a solid object from a series of layers with each layer formed on top of the previous layer. For example, <NUM>-D printing refers to a variety of processes including fused deposition modeling or fused filament fabrication, e.g., large format additive manufacturing.

Fused deposition modeling or fused filament fabrication involves building a part or article layer-by-layer by heating thermoplastic material to a semi liquid state and extruding it according to computer-controlled paths. Fused deposition modeling utilizes a modeling material and a support material. The modeling material comprises the finished piece, and the support material comprises scaffolding that can be washed away or dissolved when the process is complete. The process involves depositing material to complete each layer before the base moves along the z-axis and the next layer begins. As used herein, the z axis is the interlayer axis, the x-axis is the axis along the bead, and the y-axis if the axis across the bead (see <FIG>), and the z direction strength is the strength along the z-axis.

A large format additive manufacturing machine (BAAM™, manufactured by Cincinnati Incorporated) was used to print <NUM> inch width x <NUM> inch length x <NUM> inch height (<NUM> centimeter (cm) width x <NUM> length x <NUM> height) single-wall box-shaped parts from the compositions listed in Table <NUM>. A printed part is shown in <FIG> which is a front view, while <FIG> is a top view. The box was designed in a way so that the back wall can be used to collect tensile specimens while the front wall (with angle changes in the z and xy direction in the middle) can be used to assess the printability of the parts.

To print the box-shaped parts, the temperature profile of the extruder, which extruded a bead, was in the range of <NUM> to <NUM> for the polybutylene terephthalate (PBT)/carbon fiber (CF) samples, and <NUM> to <NUM> for the polycarbonate (PC)/CF and PC/PBT/CF samples. The temperature was gradually increased along the length of the extruder. The PBT/CF samples were processed at lower temperature than the PC/CF and PC/PBT/CF samples as the glass transition temperature (Tg) of PBT is less than that of PC. The print speed was approximately <NUM> inches/second and the screw speed was approximately <NUM> revolutions per minute (rpm). The melt pressure was maintained at less than <NUM>,<NUM> pounds per square inch (psi). Comparative composition C4 included glass fiber (GF) rather than CF.

Dumbbell shaped tensile samples were machined from the printed articles using a computer numerical control (CNC) waterjet cutter. The samples were created from each of the compositions in two directions: horizontal, with the printed beads parallel to the tensile axis (also referred to as the xz orientation), and vertical, with the printed beads perpendicular to the tensile axis (also referred to as the zx orientation). The specimens' orientations are depicted in <FIG>. The x direction indicated in <FIG> corresponds to a direction of movement of the extruder during the printing.

The dumbbell tensile samples were conditioned at drying conditions at <NUM> for <NUM> hours in dry air followed by a normalization period at <NUM> and <NUM>% relative humidity (RH) for at least eight hours before testing. An MTS EXCEED™ E45 electromechanical load frame was used to strain the samples, at a rate of <NUM> millimeters per minute (mm/min), in tension mode up to fracture. The force-displacement data was collected for further analysis. Five (<NUM>) samples from each composition and direction were tested. The averaged results are provided in Table <NUM>. Surface appearance determinations were made by naked eye and aided by a microscope.

Regarding the Corner lift measurements provided in Table <NUM>, reference is made to <FIG>, which is provided only for purposes of illustration. The Corner lift listed in Table <NUM> was an average of measured values for four corners of the printed part, and corresponds to a warpage of the part.

As used herein, the "modified ASTM D <NUM>" test method used the test standard set forth in ASTM D <NUM><NUM> but used a test specimen varying from the standard test method of ASTM D <NUM><NUM>. <FIG> illustrates the dimensions of the test specimen used in the modified ASTM D <NUM> test method referenced herein.

Parts printed from the composition Ex1 exhibited improved warpage and tensile strength as compared to the comparative compositions including: PBT/CF without the terpolymer (comparative composition <NUM>, "C1"); PC/CF without the terpolymer (comparative composition <NUM>, "C2"): PBT/PC/CF without the terpolymer (comparative composition <NUM>, "C3"); and PBT/PC/GF (comparative composition <NUM>, "C4"). In particular, C1 did not exhibit good printability. The interlayer adhesion in the printed part was poor resulting in a poor z direction tensile strength of <NUM> MPa. C2 exhibited a z direction tensile strength of <NUM> MPa, but also exhibited a corner lift of <NUM> inches (<NUM>). Z direction tensile strength of the articles printed from composition <NUM> (i.e., the PC/PBT/CF terpolymer composition) were higher than the z direction tensile strengths of articles printed from compositions containing glass fiber (C4), no terpolymer (C3), only polycarbonate and carbon fibers (C2), or only polybutylene terephthalate and carbon fibers (C1).

In particular, the tensile strength in the z direction of C1 was <NUM> MPa and the tensile strength in the z direction of C2 was <NUM> MPa. Addition of polybutylene terephthalate to C2 would expectedly negatively impact the tensile strength in the z direction of a part printed therefrom. As expected, therefore, adding the polybutylene terephthalate to the polycarbonate and CF resulted in a tensile strength between that of C1 and C2. Adding the terpolymer to the polycarbonate/polybutylene terephthalate composition produced a lower tensile strength than the polycarbonate/polybutylene terephthalate/carbon fiber (see C4 versus C3). Seemingly, adding the terpolymer to the PC/PCB/CF composition would be expected to result in a tensile strength between that of C3 and C4, i.e., between <NUM> and <NUM> MPa. However, a synergy was discovered between the polybutylene terephthalate, polycarbonate, terpolymer, and carbon fiber. That composition resulted in a surprising improvement in the tensile strength in the z direction. Specifically, the tensile strength in the z direction of composition <NUM> was <NUM> MPa.

The synergistic effect of using the PC/PBT/CF terpolymer composition, and resultant desirable warpage and tensile strength, was particularly surprising as the effect was not attained when using the composition to form an injection molded article. In particular, Table <NUM> provides tensile strength data for a regular tensile bar and weld line strength data for a double gated tensile bar manufactured by injection molding using comparative compositions C1 and C2 and composition Ex1. In large format additive manufacturing layers in the z direction as well as the double gated tensile bar, fibers do not cross from one layer to another layer.

For the injection molded samples, tensile strength of the tensile bar formed using composition Ex1 (<NUM> MPa) was between the tensile strength of the tensile bars formed using comparative compositions C1 and C2 (<NUM> and <NUM> MPa, respectively). However, weld line strength of the double gated tensile bar formed by injection molding using composition of Ex1 (<NUM> MPa) was worse than the weld line strength of both the double gated tensile bars formed by injection molding using comparative compositions C1 and C2 (<NUM> and <NUM> MPa, respectively). Thus, both the tensile strength and the weld line strength of injection molded samples formed using the PC/PBT/CF terpolymer composition were not improved over injection molded samples formed using comparative composition C1 and comparative composition C2.

A large format additive manufacturing machine (BAAM™, manufactured by Cincinnati Incorporated) was used to print <NUM> inch width x <NUM> inch length x <NUM> inch height (<NUM> centimeter (cm) width x <NUM> length x <NUM> height) single-wall box-shaped parts from the compositions listed in Table <NUM>, similar to the printed parts of C1-C4 and Ex1.

To print the box-shaped parts, the temperature profile of the extruder, which extruded a bead, was in the range of <NUM> to <NUM>. The temperature was gradually increased along the length of the extruder. The print speed was approximately <NUM> inches per second and the screw speed was approximately <NUM> revolutions per minute (rpm). The melt pressure was maintained at less than <NUM>,<NUM> psi (<NUM> MPa).

Dumbbell shaped tensile samples were machined from the printed articles using a CNC waterjet cutter. The samples were created from each of the compositions in two directions: horizontal, with the printed beads parallel to the tensile axis (also referred to as the xz orientation), and vertical, with the printed beads perpendicular to the tensile axis (also referred to as the zx orientation), similar to the printed parts of C1-C4 and Ex1.

The dumbbell tensile samples were conditioned at drying conditions at <NUM> for <NUM> hours in dry air followed by a normalization period at <NUM> and <NUM>% RH for at least eight hours before testing. An MTS EXCEED™ E45 electromechanical load frame was used to strain the samples, at a rate of <NUM> millimeters per minute (mm/min), in tension mode up to fracture. The force-displacement data was collected for further analysis. Five (<NUM>) samples from each composition and direction were tested. The averaged results are provided in Tables <NUM> and <NUM>.

Parts printed from compositions including glass fiber in addition to carbon fiber exhibited decreased tensile strength. For example, parts printed from each of comparative composition <NUM> ("C5") and comparative composition <NUM> ("C6") exhibited tensile strength in the z direction of less than <NUM> MPa, as determined by the modified ASTM D <NUM> test method. Specifically, a part printed from C6, which included <NUM> wt% glass fiber, exhibited a tensile strength in the z direction of <NUM> MPa, as determined by the modified ASTM D <NUM> test method, and a part printed from C5, which included an increased amount of <NUM> wt% glass fiber, exhibited a tensile strength in the z direction of <NUM> MPa, as determined by the modified ASTM D <NUM> test method.

Ex1, which included <NUM> to <NUM> wt% polycarbonate (specifically <NUM> wt%); <NUM> to <NUM> wt% polybutylene terephthalate (specifically <NUM> wt%); <NUM> to <NUM> wt% carbon fiber (specifically <NUM> wt%); <NUM> to <NUM> wt% ethylene acrylic ester terpolymer (specifically <NUM> wt%); and less than <NUM> wt% glass fiber (specifically <NUM> wt%), exhibited a tensile strength in the z direction of <NUM> MPa, as determined by the modified ASTM D <NUM> test method.

Glass fiber is present in the composition in an amount of less than <NUM> wt%, for example, less than <NUM> wt%, or less than <NUM> wt%, based on the total weight of the composition. The composition can be free of glass fiber. Preferably, all fibers in the composition are carbon fibers.

The various embodiments are illustrated by the following aspects.

Aspect <NUM>: A composition comprising, based on a total weight of the composition: <NUM> to <NUM> wt% of polycarbonate; <NUM> to <NUM> wt% of polybutylene terephthalate; <NUM> to <NUM> wt% of carbon fiber; <NUM> to <NUM> wt% of an ethylene acrylic ester terpolymer; and less than <NUM> wt% of glass fiber; wherein the total weight of the composition is <NUM> wt%.

Aspect <NUM>: The composition of Aspect <NUM>, comprising less than <NUM> wt% of glass fiber, preferably less than <NUM> wt% of glass fiber, based on the total weight of the composition.

Aspect <NUM>: The composition of any one of the preceding aspects, wherein the composition is free of glass fiber.

Aspect <NUM>: The composition of any one of the preceding aspects, comprising polycarbonate in an amount of <NUM> to <NUM> wt% based on the total weight of the composition.

Aspect <NUM>: The composition of any one of the preceding aspects, comprising polybutylene terephthalate in an amount of <NUM> to <NUM> wt%, based on the total weight of the composition.

Aspect <NUM>: The composition of any one of the preceding aspects, comprising carbon fiber in an amount of <NUM> to <NUM> wt%, based on the total weight of the composition.

Aspect <NUM>: The composition of any one of the preceding aspects, comprising ethylene acrylic ester terpolymer in an amount of <NUM> to <NUM> wt%, based on the total weight of the composition.

Aspect <NUM>: The composition of any one of the preceding aspects, comprising, based on the total weight of the composition, carbon fiber in an amount of <NUM> to <NUM> wt%, and ethylene acrylic ester terpolymer in an amount of <NUM> to <NUM> wt%.

Aspect <NUM>: The composition of any one of the preceding aspects, wherein the carbon fiber has a length of <NUM> millimeters to <NUM> millimeters, preferably <NUM> millimeters to <NUM> millimeter.

Aspect <NUM>: The composition of any one of the preceding aspects, wherein the carbon fiber has a diameter of <NUM> micrometers to <NUM> micrometers, preferably <NUM> micrometers to <NUM> micrometers, or <NUM> micrometers to <NUM> micrometers.

Aspect <NUM>: The composition of any one of the preceding aspects, wherein the composition comprises carbon fibers having a tensile modulus of <NUM> to <NUM> megapounds per square inch (<NUM> to <NUM> gigapascals), preferably <NUM> to <NUM> megapounds per square inch (<NUM> to <NUM> gigapascals), more preferably <NUM> to <NUM> megapounds per square inch (<NUM> to <NUM> gigapascals).

Aspect <NUM>: The composition of any one of the preceding aspects, wherein the composition comprises carbon fibers having a tensile strength of <NUM> to <NUM>,<NUM> kilopounds per square inch (<NUM>,<NUM> to <NUM>,<NUM> megapascals), preferably <NUM> to <NUM>,<NUM> kilopounds per square inch (<NUM>,<NUM> to <NUM>,<NUM> megapascals), more preferably <NUM> to <NUM> kilopounds per square inch (<NUM>,<NUM> to <NUM>,<NUM> megapascals).

Aspect <NUM>: A method of forming an article, the method comprising three dimensional printing using the composition of any one of the preceding aspects.

Aspect <NUM>: An article formed by using the composition of any one of Aspects <NUM>-<NUM>.

Aspect <NUM>: The article of Aspect <NUM>, wherein the article exhibits a tensile strength in the first direction of at least <NUM> megapascals, preferably at least <NUM> megapascals, as determined by a modified ASTM D <NUM> test method.

Aspect <NUM>: The article of Aspect <NUM> or Aspect <NUM>, wherein the article exhibits improved tensile strength as compared to a composition comprising a same amount of polycarbonate, a same amount of polybutylene terephthalate, or a combination thereof, and a same amount of carbon fiber, without an ethylene acrylic ester terpolymer.

Aspect <NUM>: The article of any one of Aspects <NUM>-<NUM>, wherein the article exhibits improved warpage as compared to a composition comprising a same amount of polycarbonate, a same amount of polybutylene terephthalate, or a combination thereof, and a same amount of carbon fiber, without an ethylene acrylic ester terpolymer.

The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of, any appropriate components or steps herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any steps, components, materials, ingredients, adjuvants, or species that are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles.

"Or" means "and/or" unless clearly indicated otherwise by context. The terms "first," "second," and the like, "primary," "secondary," and the like, as used herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

The endpoints of all ranges directed to the same component or property are inclusive and independently combinable (e.g., ranges of "less than or equal to <NUM> wt%, or <NUM> wt% to <NUM> wt%," is inclusive of the endpoints and all intermediate values of the ranges of "<NUM> wt% to <NUM> wt%," etc.). Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group. As used herein, the total amount of the components in the composition is <NUM> wt%.

Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this disclosure belongs. A "combination" is inclusive of blends, mixtures, alloys, reaction products, and the like.

Claim 1:
A composition comprising, based on a total weight of the composition:
<NUM> to <NUM> wt% of polycarbonate;
<NUM> to <NUM> wt% of polybutylene terephthalate;
<NUM> to <NUM> wt% of carbon fiber;
<NUM> to <NUM> wt% of an ethylene acrylic ester terpolymer; and
less than <NUM> wt% of glass fiber;
wherein the total weight of the composition is <NUM> wt%.