WO2019195689A1 - Compositions pour fabrication additive - Google Patents

Compositions pour fabrication additive Download PDF

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Publication number
WO2019195689A1
WO2019195689A1 PCT/US2019/026006 US2019026006W WO2019195689A1 WO 2019195689 A1 WO2019195689 A1 WO 2019195689A1 US 2019026006 W US2019026006 W US 2019026006W WO 2019195689 A1 WO2019195689 A1 WO 2019195689A1
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WIPO (PCT)
Prior art keywords
additive manufacturing
carbon atoms
weight percent
aliphatic
repeat units
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PCT/US2019/026006
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English (en)
Inventor
Sik BOEN
David A. BUZZELLI
Berardino D'achille
Yanyan Cao
Lynda Kaye Johnson
Rahul B. Kasat
Thomas E. Lovelace
Michael Joseph Molitor
Jennifer Leigh Thompson
Kai Qi
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E. I. Du Pont De Nemours And Company
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Publication of WO2019195689A1 publication Critical patent/WO2019195689A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
    • C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
    • C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids
    • C08G69/265—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids from at least two different diamines or at least two different dicarboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
    • C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
    • C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids
    • C08G69/32—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids from aromatic diamines and aromatic dicarboxylic acids with both amino and carboxylic groups aromatically bound
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
    • C08L77/06—Polyamides derived from polyamines and polycarboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group

Definitions

  • additive manufacturing(AM) compositions of use in preparing 3D printed articles using material extrusion additive manufacturing processes Disclosed herein are additive manufacturing(AM) compositions of use in preparing 3D printed articles using material extrusion additive manufacturing processes.
  • polyamide compositions may be used to prepare filaments and pellets, which may be used in fused filament fabrication and pellet additive manufacturing processes, respectively. Also disclosed herein are 3D printed articles prepared by such processes.
  • Additive manufacturing also known as 3 -dimensional (3D) printing, is used to print or otherwise manufacture 3D parts from digital representations of the 3D parts (e.g ., AMF and STL format files) using one or more additive manufacturing techniques. Successive layers of a composition are deposited and fused together to produce an article having a defined shape. By the term“fused” is meant that the successive layers adhere to one another. Examples of commercially available additive manufacturing techniques include material extrusion, jetting, selective laser sintering, powder/binder jetting, electron-beam melting, and stereolithographic processes.
  • FFF fused filament fabrication
  • PAM pellet additive manufacturing
  • BAAM big area additive manufacturing
  • LSAM large-scale additive manufacturing
  • FFF extrusion-based processes
  • PAM extrusion-based processes
  • a filament, fiber, or strand enters the 3D printing device and a 3D object is formed by extruding the filament through a heated nozzle, where the filament is melted, to form layers and where each layer hardens after extrusion, i.e ., layer-by- layer deposition.
  • Pellet additive manufacturing processes utilize polymer pellets and powders, fiber reinforcements, and other fillers and additives as the feedstock with the additive manufacturing system combining melting, compounding, and extrusion functions, enabling stiff, highly reinforced materials to be printed.
  • materials used in extrusion-based AM are compatible with a broad nozzle/hot-end temperature range.
  • increasing the nozzle temperature can improve interlayer adhesion and increase the mechanical performance of a 3D-printed part.
  • materials that are capable of being printed at lower nozzle temperatures, while still retaining functional and aesthetic properties exhibit broad compatibility with a wide variety of printers.
  • materials used in fused filament fabrication to be capable of being wound onto a spool as a continuous strand with no breakages.
  • Moisture-tolerant materials are desirable for use in FFF, PAM and other extrusion-based 3D printing processes.
  • 3D printers are used in a broad range of environments, often with high relative humidity. If the feedstock has absorbed moisture, printing at too high of a temperature will result in macroscopic bubbles, a rough surface, and compromised mechanical properties. Low water absorption is also important for retaining the properties of the printed part, as water absorption alters dimensions as well as lowers mechanical properties such as stiffness and strength.
  • parts printed by extrusion-based processes are often printed with soluble support structures, which are typically removed by immersing the printed part in an aqueous bath.
  • Polyamides such as PA66 and PA6, are easy to process and have high melting points and high heat deflection temperatures, particularly when they have glass-fiber or carbon-fiber reinforcement or comprise mineral fillers. However, they typically have high water absorption and exhibit warpage or curl when printed due to rapid crystallization. Winding these highly crystalline polyamides as a continuous strand on a spool can be challenging, particularly when the composition incorporates glass or carbon reinforcement.
  • Long-chain aliphatic polyamides such as those composed of aminoundecanoic acid (PA11), laurolactam (PA12), or a combination of dodecanediamine and dodecanedioic acid (PA1212) have low water absorption and relatively low warpage when printed, but have low melting points, low modulus and low strength, even when dry. They are undesirable for technical applications at relatively high temperatures.
  • Semicrystalline, semiaromatic polyamides have reduced water absorption and mechanical properties are substantially retained after water absorption.
  • melting points are often too high to be processed by most desktop FFF printers.
  • High rates of crystallization of many semicrystalline polyamides adversely affect inter layer adhesion and induces shrinkage that may distort the article as it is printed.
  • blends of semicrystalline and amorphous polyamides have been printed to slow the crystallization rate.
  • compositions for fused filament fabrication comprising substantially miscible blends of at least one semi-crystalline polyamide and at least one amorphous polyamide with preferred semicrystalline polyamides selected from non-aromatic polyamides including PA6, PA66, and PA12.
  • U.S. Patent 5,391,640 discloses a blend of a conventional polyamide and an amorphous polyamide wherein such blends are relatively insensitive to humidity and exhibit good film barrier properties.
  • WO2017153586A1 discloses a semicrystalline copolyamide for FFF comprising at least 0.5 wt% of a cyclic monomer.
  • a representative copolyamide of this application is PA-6/IPDT wherein IPD is isophoronediamine and T is terephthalic acid and wherein IPDT is present at 1 wt% in the copolyamide.
  • compositions comprising semi-crystalline copolyamides for use in material extrusion additive manufacturing processes such as FFF and PAM that result in tailored features and mechanical properties of the resulting articles and/or an improved processing window.
  • Such compositions should be processable over a broad temperature range and exhibit a combination of low curl/warpage, low moisture absorption, and good mechanical properties of both dry and conditioned parts.
  • FIGURE l is a view of test bars in various directions including vertical, edge, or flat.
  • MI Melt Index
  • wt. % refers to weight percent
  • mm refers to millimeters.
  • mol. % refers to mole percent
  • IV refers to inherent viscosity
  • RV refers to relative viscosity
  • the article “a” refers to one as well as more than one and does not necessarily limit its referent noun to the grammatical category of singular number.
  • the terms“about” and“at or about”, when used to modify an amount or value refers to an approximation of an amount or value that is more or less than the precise amount or value recited in the claims or described herein. The precise value of the
  • the term“article” refers to an unfinished or finished item, thing, object, or an element or feature of an unfinished or finished item, thing or object.
  • the term “article” may refer to any item, thing, object, element, device, etc. that has a form, shape, configuration that may undergo further processing in order to become a finished article.
  • the term “article” refers to an item, thing, object, element, device, etc. that is in a form, shape, configuration that is suitable for a particular use/purpose without further processing of the entire entity or a portion of it.
  • An article may comprise one or more element(s) or subassembly(ies) that either are partially finished and awaiting further processing or assembly with other elements/subassemblies that together will comprise a finished article.
  • article may refer to a system or configuration of articles.
  • additive manufacturing refers to a process of joining materials together, usually in a layer-by-layer process, to form an article.
  • additive manufacturing system refers to a set of connected parts forming a unit or units that prints, builds, or otherwise produces 3D items and/or support structures at least in part using additive manufacturing and may be a stand-alone unit, a sub-unit of a larger unit or production line, and/or may include other nonadditive manufacturing features, such as subtractive-manufacturing features, pick-and-place features, and two-dimensional printing features.
  • the term“material extrusion” refers to a manufacturing process that is used to build a three-dimensional (3D) model from a digital representation of the 3D model in a layer-by-layer manner by selectively dispensing a flowable material through a nozzle or orifice.
  • thermoplastic material is melted or heated to a flowable state and extruded as a series of layers, which cool down to form a 3D part.
  • Feedstocks for material extrusion can include filaments, polymer pellets and powders, fiber reinforcements, and other fillers and additives.
  • Material extrusion techniques include fused filament fabrication, pellet additive manufacturing big area additive manufacturing and large-scale additive manufacturing, as well as other material extrusion technologies as defined by ASTM F2792-l2a.
  • FFF fused filament fabrication
  • FDM fused deposition modeling
  • ratio of vertical to flat tensile strength refers to the tensile strength of a tensile bar printed in the vertical (zx) direction (see Figure 1) divided by the tensile strength of a tensile bar printed in the flat (xy) direction, where the tensile strength is measured on test samples pursuant to ISO 527-2:2012 and the printing of both flat and vertical bars is conducted with the same printer, printing conditions and parameters. Accordingly, the ratio of vertical to flat tensile strength is an indicator for the strength of interlayer adhesion and the degree of anisotropy of properties of printed 3D parts.
  • Curl refers to the degree to which a 3D printed test sample bends at the end of the sample relative to a flat test sample in which the entire test sample is flat or straight with no bending. Curl is measured pursuant to the Curl Bar Test.
  • the term“temperature range” refers to the range of nozzle or hot-end temperatures useful for 3D-printing parts with functional performance and desirable aesthetic surface appearance as observed by the unaided human eye. In other words, it is the temperature range in which no visible defects are observable on the surface of a printed test cylinder pursuant to the Temperature Range Test.
  • dry-as-printed or“DAP” refers to test samples printed under a nitrogen environment, with the printed test samples kept under nitrogen until being sealed in aluminum bags under vacuum and stored until being tested.
  • conditioned refers to articles/test samples printed under a nitrogen environment and conditioned at 23 °C and 50% RH for at least 40 h prior to testing.
  • ambient conditions refers to an environment with a
  • aliphatic polyamide refers to a polyamide that comprises greater than 95 mole percent aliphatic repeat units derived from one or more aliphatic dicarboxylic acids with 6 to 20 carbon atoms and one or more aliphatic diamines with 4 to 20 carbon atoms.
  • long- chain aliphatic polyamide refers to an aliphatic polyamide with a repeating unit monomer length comprising greater than or equal to 10 carbon atoms.
  • any range set forth herein expressly includes its endpoints unless explicitly stated otherwise. Setting forth an amount, concentration, or other value or parameter as a range specifically discloses all possible ranges formed from any possible upper range limit and any possible lower range limit, regardless of whether such pairs of upper and lower range limits are expressly disclosed herein. Polymer compositions, compounds, processes and articles described herein are not limited to specific values disclosed in defining a range in the description.
  • AM compositions which may be used in material extrusion additive manufacturing processes and may be in the form of filaments, pellets, and/or powders.
  • the desirable additive manufacturing process in which these AM compositions may be used is fused filament fabrication, wherein said AM compositions are in the form of filaments, especially filaments which may be easily wound onto spools or reels, and pellet additive manufacturing, wherein said AM compositions are in the form of pellets of appropriate size which may be readily fed into the extruder of a PAM printer.
  • the AM compositions are often compounded, preferably into well mixed or homogeneous mixtures, prior to preparing said filaments and pellets.
  • Additive Manufacturing compositions disclosed herein comprise:
  • additive manufacturing compositions comprising:
  • copolyamide comprises
  • 3D printed articles prepared from said filaments and pellets by material extrusion additive manufacturing processes.
  • AM compositions disclosed herein may be used in material extrusion additive manufacturing processes to prepare 3D printed articles.
  • filaments for use in fused filament fabrication processes and pellets for use in pellet additive are particularly disclosed herein.
  • said filaments and pellets comprising a polyamide composition comprising a mixture of at least one semi-crystalline copolyamide, at least one amorphous copolyamide, at least one aramid material, and optionally at least one additive.
  • An advantage of the AM compositions disclosed herein is that the ratio of semi-crystalline copolyamide to amorphous copolyamide may be varied to alter the physical properties of 3D printed articles comprising these compositions.
  • AM compositions disclosed herein exhibit desirable wear properties.
  • 3D printed articles prepared from AM compositions disclosed herein especially when using fused filament fabrication and pellet additive manufacturing processes, exhibit a good balance of mechanical properties, lower warpage, less distortion, and desirable printability upon cooling compared to articles prepared using AM compositions which comprise only a semi crystalline copolyamide or only an amorphous copolyamide.
  • Semi-crystalline copolyamide A used in the AM compositions described herein is a copolyamide comprising 5 to 40 mole percent aromatic repeat units (a-l), preferably 10 to 30 mole percent (a-l), and 60 to 95 mole percent aliphatic repeat units (a-2), preferably 70 to 90 mole percent (a-2).
  • Aromatic repeat units (a-l) comprise at least one aromatic dicarboxylic acid with 8 to 20 carbon atoms such as terephthalic acid, isophthalic acid, and 2,6-napthalenedioic acid. Terephthalic acid and isophthalic acid are preferred, with terephthalic acid most preferred.
  • Aliphatic repeat units (a-2) comprise at least one aliphatic dicarboxylic acid with 6 to 20 carbon atoms and may include adipic acid, decanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, and octadecanedioic acid.
  • Dodecanedioic acid, decanedioic acid, hexadecanedioic acid, and octadecanedioic acid are preferred aliphatic dicarboxylic acids, with dodecanedioic acid and decanedioic acid being most preferred.
  • Aromatic repeat units (a-l) and aliphatic repeat units (a-2) may each comprise at least one aliphatic diamine having from 4 to 20 carbon atoms and may include hexamethylenediamine (HMD), l, l0-decanediamine, l, l2-dodecanediamine, and 2-methyl-l,5-pentamentylenediamine with hexamethylenediamine being preferred.
  • HMD hexamethylenediamine
  • l l0-decanediamine
  • l l2-dodecanediamine
  • 2-methyl-l,5-pentamentylenediamine with hexamethylenediamine being preferred.
  • Non-limiting examples of semi-crystalline copolyamides useful in the AM compositions include those selected from the group consisting of: poly(hexamethylene
  • hexanamide/hexamethylene terephthal amide or PA 66/6T having a molar ratio of 66:6T ranging from (95/5) to (60/40), preferably (90/10) to (70/30), and more preferably (85/15) to (75/25); poly(hexamethylene dodecanamide/hexamethylene terephthalamide) or PA 612/6T having a molar ratio of 6l2:6T ranging from (95/5) to (60/40), preferably (90/10) to (70/30), and more preferably (85/15) to (75/25); poly(hexamethylene decanamide/hexamethylene terephthal amide) or PA 610/6T having a molar ratio of 6lO:6T ranging from (95/5) to (60/40), preferably (90/10) to (70/30), and more preferably (85/15) to (75/25); poly(hexamethylene
  • the semi-crystalline copolyamide is selected from the group consisting of PA 610/6T, PA 612/6T, PA 614/6T, PA 616/6T, and PA 618/6T.
  • the concentration of semi-crystalline copolyamide in the AM compositions disclosed herein ranges from about 5 to 94.9 weight percent, preferably from about 5 to 90, more preferably from about 5 to 80, and most preferably from about 15 to 69.9 weight percent based on the total weight percent of semi-crystalline copolyamide (A), amorphous copolyamide (B), material (C), and additive (D) in the polyamide composition with the weight percent of all ingredients equal to 100 weight percent.
  • Amorphous copolyamide B used in the AM compositions described herein is a copolyamide comprising 60 to 90 mole percent aromatic repeat units (b-l), preferably 70 to 90 mole percent (b-l), and 10 to 40 mole percent aromatic repeat units (b-2), preferably 10 to 30 mole percent (b-2).
  • Amorphous copolyamide B used in the AM compositions described herein is a copolyamide having two or more amides and/or diamide molecular repeat units in which one repeat unit comprises terephthalic acid and the second repeat unit comprises isophthalic acid.
  • the diamines which may be used to prepare amorphous copolyamide B includes linear, branched, or cyclic aliphatic diamines with 4 to 20 carbon atoms.
  • suitable diamines include hexamethylenediamine (HMD), l,l0-decanediamine, l,l2-dodecanediamine, 1,4- cyclohexanediamine, and 2-methyl-l,5-pentamentylenediamine with hexamethylenediamine being preferred.
  • HMD hexamethylenediamine
  • l,l0-decanediamine l,l2-dodecanediamine
  • 1,4- cyclohexanediamine 1,4- cyclohexanediamine
  • 2-methyl-l,5-pentamentylenediamine with hexamethylenediamine being preferred.
  • Non-limiting examples of amorphous copolyamides useful in the AM compositions include those selected from the group consisting of: poly(hexamethylene
  • PA 6I/6T having a molar ratio of 6I:6T ranging from (60/40) to (95/5), preferably (70/30) to (80/20).
  • the concentration of amorphous copolyamide in the AM compositions disclosed herein ranges from about 5 to 94.9 weight percent, preferably from about 5 to 90, more preferably from 5 to 50, and most preferably from 5 to 30 weight percent based on the total weight percent of semi-crystalline copolyamide (A), amorphous copolyamide (B), material (C), and additive (D) in the polyamide composition with the weight percent of all ingredients equal to 100 weight percent.
  • the weight ratio of semi-crystalline copolyamide (A) to amorphous copolyamide (B) in the AM compositions ranges from about 95:5 to 5:95, preferably from 90: 10 to 10:90, more preferably from 85: 15 to 65:35 depending on the physical properties desired in the 3D printed articles.
  • AM compositions disclosed herein for use in additive manufacturing processes comprise aramid materials such as aramid fibers, particulate aramid, and combinations of these.
  • Aramid materials are prepared from polyamides wherein at least 85% of the amide (-CONH-) linkages are attached directly to two aromatic rings.
  • a preferred aromatic polyamide is para-aramid due to exceptional tensile strength and modulus.
  • a preferred para-aramid is poly (p-phenylene terephthalamide), which is called PPD-T.
  • PPD-T poly (p-phenylene terephthalamide)
  • Aramid fibers and their production are also disclosed in US 3,767,756; US 4,172,938; US 3,869,429; US 3,869,430; US 3,819,587; US 3,673, 143; US 3,354,127; and US 3,094,511.
  • Para- aramid materials are available under the registered trademark Kevlar® from E. I. Du Pont de Nemours and Company, Wilmington, DE (DuPont).
  • the weight percent of aramid materials in the polyamide composition may range from about 0.1% to 50%, preferably 1% to 30%, although concentrations between 1% and 25% or between 5% to 22% are also contemplated based on the total weight percent of ingredients (A), (B), (C), and (D) in the polyamide composition .
  • Aramid fibers are generally continuous or from 0.01 to 50 mm in length, and preferably about 1 to 10 mm; and the fibers generally have a diameter of 0.01 to 200 microns and preferably about 5 to 50 microns. Additionally, it is preferred that the fibers have a surface area of greater than 5 sq.m./g and a ratio of length to diameter of 10 to 10,000, preferably 20 to 1000.
  • the fibers can be used in the form of floe or pulp. Floe is made by cutting fibers into short lengths without significant fibrillation of the fiber ends; and the lengths of floe fibers may range from 1 to 10 mm. Pulp can be made by grinding fibers to fibrillate the ends of short pieces of the fiber material. An example of pulp and a method for making it can be found in the Research
  • Pulp can, also, be made by casting a polymerizing solution of polymer material and grinding the solution, once solidified, such as is disclosed in US
  • Pulp particles differ from floe, as so-called short fibers, by having a multitude of fibrils or tentacles extending from the body of each pulp particle. Those fibrils or tentacles provide minute, hair-like, anchors for reinforcing composite materials and cause the pulp to have a very high surface area.
  • Aramid pulp and pulp-like particles generally have a surface area of 5 to 15 sq.m./g.
  • Particulate aramid is meant aramid particles whose average largest dimension is less than 500 micrometers and preferably is less than 250 micrometers.
  • the particles may be of any shape, for example short fibers, fibrils, fibrids, irregular, spherical, disc-shaped, etc.
  • Particulate aramid includes aramid powders, aramid micropulps, and combinations of these.
  • aramid powders substantially fibril-free, relatively low surface area, aramid particle powder.
  • the individual particles are generally rounded, in shape, and are substantially without fibrils or tentacles.
  • the aramid powder usually has a surface area, as determined by the BET method using nitrogen, of 2 sq.m./g or less, and an average diameter from about 50 to 500 micrometers, often from about 75 to 250 micrometers.
  • Aramid powders are made by comminuting aramid polymer to the desired size.
  • aramid polymer made in accordance with the teachings in US 3,063,966 and 4,308,374 is finished in the form of a water-wet crumb, dried and then pulverized in a hammer mill to an average diameter of 50 to 500 micrometers. Once dried and pulverized, aramid powders of the desired size range can be isolated for use, such as by sieving.
  • Para-aramid fibers are particularly suited for the manufacture of pulp and micropulp due to their fibrillar morphology.
  • Para-aramid pulp such as Kevlar® pulp is a fibrillated fiber product that is manufactured from yarn by chopping into staple then mechanically abrading in water to partially shatter the fibers.
  • Kevlar® pulps must be kept moist to prevent the fibrillated structure from collapsing if they are to be highly dispersible in different matrices.
  • United States patents 5,084,136 and 5,171 ,402 describe such para-aramid pulps.
  • Aramid pulps may comprise fibers having a fiber length of from 0.5 to 1.1 mm and a specific surface area of from 5 to 15 sq.m./g, whereas aramid micropulps comprise fibers having a length-weighted average length of from 20 to 500 micrometers, as measured optically, and a relative specific surface area of from 18 to 28 sq.m./g, as measured by the B.E.T. method using nitrogen.
  • the fibers of the aromatic pulp and micropulp may be aromatic polyamide, aromatic copolyamide, polyazole, or polyacrylonitrile.
  • Any combination of aramid fibers and particulate aramids may be used in the AM compositions.
  • AM compositions disclosed herein for use in additive manufacturing processes may optionally comprise additional additives such as reinforcing agents other than aramid fibers and/or pulps, tougheners, fillers, adhesion promoters or compatibilizers, crystallization accelerators or crystallization retarders, flow aids, lubricants, mold-release agents, colorants, plasticizers, antioxidants, heat stabilizers, processing aids, flame retardants including halogen- free flame-retardants and synergists, antistatic agents, high temperature copolyamides, aliphatic polyamides, and mixtures of any of these additives.
  • additional additives such as reinforcing agents other than aramid fibers and/or pulps, tougheners, fillers, adhesion promoters or compatibilizers, crystallization accelerators or crystallization retarders, flow aids, lubricants, mold-release agents, colorants, plasticizers, antioxidants, heat stabilizers, processing aids, flame retardants including halogen- free flame-re
  • the concentration of additive D in the AM compositions when present, may range from about 0.1 weight percent up to about 50 weight percent based on the total weight of (A), (B), (C), and (D) in the polyamide composition.
  • reinforcing agents as additive (D) which may be used in the AM compositions include fibrous and nonfibrous materials and mixtures of these.
  • fibrous materials include circular and noncircular glass fibers, carbon fibers, silica carbide fibers, boron fibers, cellulose fibers, boron nitride fibers, ceramic fibers, and combinations of these.
  • Nonfibrous materials include materials such as solid glass beads, hollow glass beads, glass flake, glass microflake, ground glass, calcium carbonate, talc, mica, wollastonite, calcined clay, kaolin, diatomite, magnesium sulfate, magnesium silicate, barium sulfate, titanium dioxide, sodium aluminum carbonate, barium ferrite, potassium titanate nanocellulose, silicate, quartz, amorphous silicates, magnesium carbonate, magnesium hydroxide, sodium aluminum carbonate, aluminum oxide, chalk, lime, feldspar, permanently magnetic or respectively magnetizable metal compounds and/or alloys, electrically conductive materials, thermally conductive materials, and mixtures thereof. Any combination of fibers and nonfibrous materials may be used as additive (D).
  • D additive
  • tougheners which may be used in the AM compositions include
  • a functionalized toughener has attached to it reactive functional groups which can react with the polyamide.
  • Such functional groups are usually“attached” to the polymeric toughener by grafting small molecules onto an already existing polymer or by copolymerizing a monomer containing the desired functional group when the polymeric toughener molecules are made by copolymerization.
  • maleic anhydride may be grafted onto a hydrocarbon rubber (such as an ethylene/a-olefm or ethylene/a-olefm/diene copolymer, an a- olefin being a straight chain olefin with a terminal double bond such as propylene, 1 -butene or 1- octene) using free radical grafting techniques.
  • a hydrocarbon rubber such as an ethylene/a-olefm or ethylene/a-olefm/diene copolymer, an a- olefin being a straight chain olefin with a terminal double bond such as propylene, 1 -butene or 1- octene
  • the resulting grafted polymer has carboxylic anhydride and/or carboxyl groups attached to it.
  • functionalized polymeric tougheners include Fusabond ® , Surlyn ® and TRX ® tougheners (E. I. DuPont de Nemours
  • Ethylene copolymers are an example of a polymeric toughening agent wherein the functional groups are copolymerized into the polymer, for instance, a copolymer of ethylene and a (meth)acrylate monomer containing the appropriate functional group.
  • ethylene copolymers include ethylene terpolymers and ethylene multi -polymers, i.e. having greater than three different repeat units.
  • (meth)acrylate means the compound may be either an acrylate, a methacrylate, or a mixture of the two.
  • Useful functionalized comonomers for copolymerizing with ethylene include (meth)acrylic acid, carbon monoxide, sulfur dioxide, acrylonitrile, maleic anhydride, maleic acid diesters, (meth)acrylic acid, maleic acid, maleic acid monoesters, itaconic acid, fumaric acid, fumaric acid monoesters and potassium, sodium and zinc salts of said preceding acids, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2- isocyanatoethyl (meth)acrylate, glycidyl vinyl ether.
  • ethylene and a functionalized comonomer other monomers may be copolymerized into such a polymer, such as vinyl acetate and unfunctionalized (meth)acrylate esters such as ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate and cyclohexyl (meth)acrylate.
  • vinyl acetate and unfunctionalized (meth)acrylate esters such as ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate and cyclohexyl (meth)acrylate.
  • Another functionalized toughener is a polymer having carboxylic acid metal salts.
  • Such polymers may be made by grafting or by copolymerizing a carboxyl or carboxylic anhydride containing compound to attach it to the polymer.
  • Useful materials of this sort include Surlyn ® ionomers of ethylene copolymers (E. I. DuPont de Nemours & Co. Inc., Wilmington, DE) comprising ethylene and a C to Cs a, b ethylenically unsaturated carboxylic acid wherein the carboxylic acid functionalities are at least partially neutralized with a metal, and the metal neutralized maleic anhydride grafted ethylene/a-olefm polymer described above.
  • Metal cations for these carboxylate salts include Zn, Li, Na, Mg and Mn.
  • the ionomer may further comprise an additional comonomer selected from alkyl acrylate, alky! methacrylate, or combinations of these.
  • the comonomer may be present in a range from 0.1 wt% to about 40 wt% based on the total weight of all monomers used to prepare the ionomer.
  • the alkyl groups of the alkyl acrylate and/or alkyl methacrylate may comprise from 1 to 8 carbon atoms with suitable alkyl groups chosen from among, for example, methyl, ethyl, propyl, and butyl such as n-butyl, sec-butyl, isobutyi and tert-butyl.
  • ionomers may further comprise a reactive comonomer, such as maleic anhydride monoethylester, that can potentially react with the polyamide.
  • the reactive comonomer may be present in a range from 0.1 wt% to about 10 wt%, preferably from about 0.5 wt% to about 7 wt%, based on the total weight of all monomers used to prepare the ionomer.
  • ionomers may be characterized by a melt index ranging from about 0.5 g/lO minutes to 50 g/lO minutes using a 2.16 kg weight measured according to ASTM D1238-13. It has also been discovered that some functionalized tougheners improve z-directional properties of these articles, as indicated by a ratio of vertical :flat tensile strength of greater than or equal to 0.5, 0.6 or 0.7.
  • Preferred functionalized polymeric tougheners useful in improving the relative vertical tensile strength of 3D printed articles include those selected from the group consisting of ionomers of ethylene copolymers comprising ethylene and a C ⁇ to Cs a, b ethylenically unsaturated carboxylic acid, wherein the carboxylic acid functionalities are at least partially neutralized with a metal, and ethylene/(meth)acrylate, ethyl ene/a-olefm or ethylene/a- olefm/diene copolymers grafted with an unsaturated carboxylic anhydride.
  • Preferred ionomers of ethylene copolymers further comprise a reactive comonomer, an alkyl acrylate, an alkyl methacrylate or combinations of these, wherein the alkyl group comprises 1 - 8 carbon atoms.
  • Preferred alkyl acrylates and alkyl methacrylates comprise 4 to 8 carbon atoms.
  • Reactive comonomers are selected from the group consisting of maleic anhydride, maleic acid diesters, (meth)acrylic acid, maleic acid, maleic acid monoesters, itaconic acid, fumaric acid, fumaric acid monoesters, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-isocyanatoethyl
  • (meth)acrylate and glycidyl vinyl ether are preferred reactive comonomers.
  • Preferred reactive comonomers include maleic acid monoesters.
  • a preferred metal for neutralization is zinc.
  • the functionalized polymeric toughener contain a minimum of about 0.5 and more preferably 1.0 weight percent of repeat units and/or grafted molecules containing functional groups or carboxylate salts (including the metal) and a maximum of about 16, more preferably about 13, and very preferably about 10 weight percent of monomers containing functional groups or carboxylate salts (including the metal). It is to be understood than any preferred minimum amount may be combined with any preferred maximum amount to form a preferred range. There may be more than one type of functional monomer present in the polymeric toughener, and/or more than one polymeric toughener present in the composition for extrusion additive manufacturing.
  • an ionomer and an ethylene/a-olefm copolymer grafted with an unsaturated carboxylic anhydride may be present.
  • the toughness of the composition is increased by increasing the amount of functionalized toughener.
  • increasing these amounts may also increase the melt viscosity, and the melt viscosity should preferably not be increased so much that 3D printing is made difficult.
  • Nonfunctionalized tougheners may also be present.
  • Nonfunctionalized tougheners include polymers such as ethylene/a-olefm/diene (EPDM) rubber, polyolefins including polyethylene (PE) and polypropylene, and ethylene/a-olefm rubbers such as ethylene/l-octene copolymers available as ENGAGE ® polymers from The Dow Chemical Company, Midland Michigan.
  • EPDM ethylene/a-olefm/diene
  • PE polyethylene
  • polypropylene polypropylene
  • ethylene/a-olefm rubbers such as ethylene/l-octene copolymers available as ENGAGE ® polymers from The Dow Chemical Company, Midland Michigan.
  • nonfunctional tougheners include styrene based polymers such as acrylonitrile- styrene copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene-acrylate copolymers, styrene-isoprene-styrene copolymers, styrene-hydrogenated isoprene-styrene copolymers, styrene-butadiene-styrene copolymers, and styrene-hydrogenated butadiene-styrene copolymers.
  • styrene based polymers such as acrylonitrile- styrene copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene-acrylate copolymers, styrene-isopren
  • acrylonitrile-butadiene-styrene is a terpolymer made by polymerizing styrene and acrylonitrile in the presence of polybutadiene.
  • the monomer proportions can vary from 15 to 35% acrylonitrile, 5 to 30% butadiene and 40 to 60% styrene.
  • the presence of tougheners in the AM compositions can improve the impact strength of 3D printed articles from about 1.4 to greater than 10 times the impact strength of an identical 3D printed article but which does not comprise a toughener.
  • Compositions disclosed herein may comprise up to 50 weight percent of one or more tougheners, preferably from 0.1 to 40, more preferably from about 2 to 30, and most preferably from 5 to 20 weight percent, based on the total weight of components A and B.
  • high temperature copolyamides which may be used as additive (D) in the AM compositions disclosed herein include, for example, poly(hexamethylene
  • terephthalamide/hexamethylene dodecanamide or PA 6T/612 having a molar ratio of 6T:6l2 ranging from (50/50) to (80/20), preferably (60/40) to (70/30); poly(hexamethylene
  • terephthalamide/hexamethylene decanamide or PA 6T/610 having a molar ratio of 6T:6lO ranging from (50/50) to (80/20), preferably (60/40) to (70/30); poly(hexamethylene
  • terephthalamide/hexamethylene hexadecanamide or PA 6T/616 having a molar ratio of 6T:6l6 ranging from (55/45) to (80/20), preferably (60/40) to (70/30); poly(hexamethylene
  • terephthalamide/hexamethylene octadecanamide or PA 6T/618 having a molar ratio of 6T:6l8 ranging from (55/45) to (80/20), preferably (60/40) to (70/30); poly(hexamethylene adipamide/ hexamethylene ter ephthal amide or PA 66/6T having a molar ratio of 66:6T ranging from (40:60 to (70:30); poly(hexamethylene terephthalamide/methylpentylene ter ephthal amide) or PA 6T/DT having a molar ratio ranging from (30:70) to (70:30); and poly(hexamethylene ter ephthal amide/ hexamethylene isophthalamide/caprolactam or PA 6T/6I/6 having a molar ratio ranging from (55:30: 15) to (75:20:5).
  • Additive (D) may also comprise one or more aliphatic polyamide(s).
  • aliphatic polyamides useful as additive (D) include those selected from the group consisting of: poly(s- caprolactam) (PA6), poly(hexamethylene hexanediamide/( e-caprolactam) (PA66/6), poly(hexamethylene hexanediamide) (PA66), poly (hexamethylene decanediamide) (PA610), poly(hexamethylene dodecanediamide) (PA612), poly(decamethylene decanediamide) (PA1010), poly(l l- aminoundecanamide) (PA11), and poly(l2-aminododecanamide) (PA12).
  • PA6 poly(s- caprolactam)
  • PA66/6 poly(hexamethylene hexanediamide/( e-caprolactam)
  • PA66 poly(hexamethylene hexanediamide)
  • PA610 poly(
  • Preferred aliphatic polyamides include PA6, PA66/6, PA66, PA610, PA612, PA1010, PA11 and PA12.
  • additive (D) comprises one or more long-chain aliphatic polyamide(s).
  • Preferred long-chain polyamides include PA610, PA612, PA1010, PA612, PA11, and PA12, with PA1010 most preferred.
  • high temperature copolyamides which may be used in the AM compositions disclosed herein as additive (D) include, for example, poly(hexamethylene
  • terephthalamide/hexamethylene dodecanamide or PA 6T/612 having a molar ratio of 6T:6l2 ranging from (50/50) to (80/20), preferably (60/40) to (70/30); poly(hexamethylene
  • terephthalamide/hexamethylene decanamide or PA 6T/610 having a molar ratio of 6T:6lO ranging from (50/50) to (80/20), preferably (60/40) to (70/30); poly(hexamethylene
  • terephthalamide/hexamethylene hexadecanamide or PA 6T/616 having a molar ratio of 6T:6l6 ranging from (55/45) to (80/20), preferably (60/40) to (70/30); and poly(hexamethylene terephthalamide/hexamethylene octadecanamide) or PA 6T/618 having a molar ratio of 6T:6l8 ranging from (55/45) to (80/20), preferably (60/40) to (70/30).
  • additives (D) disclosed herein may be used in any concentration ratio in the AM compositions.
  • compositions disclosed herein when in the form of filaments, pellets or powders, and comprising at least one semi-crystalline copolyamide having a specific molar ratio of aromatic repeat units and aliphatic repeat units in combination with an amorphous copolyamide having a specific 6I:6T molar ratio, and wherein the weight ratio of the semi-crystalline copolyamide to amorphous copolyamide is within a defined range, may be used to manufacture 3D printed articles which exhibit various combinations of low moisture absorption, low warpage, dimensional stability, spoolable, a good balance of mechanical properties, as well as having broad processing windows to prepare 3D printed articles.
  • the specific combinations of semicrystalline and amorphous copolyamides disclosed herein exhibit broad compatibility with each other over a wide range of concentrations, enabling the optimization of the printing process and the tailoring of mechanical, chemical and visual properties of the resulting 3D printed articles. Compatibility of the semicrystalline and amorphous copolyamides is important to achieving 3D printed articles having desirable properties.
  • An advantage of the AM compositions disclosed herein is they enable the production of filaments that can be spooled for use in FFF processes to prepare 3D printed articles. Such articles exhibit desirable properties such as reduced warpage, superior printing capability, high dimensional accuracy, and improved surface appearance compared to articles produced by filaments from AM compositions comprising either semi-crystalline copolyamides or amorphous copolyamides alone.
  • Articles 3D printed from these spooled filaments exhibit mechanical properties which are similar for both dry and conditioned articles and exhibit desirable relative strengths and high heat deflection temperatures. Surprisingly, the visible surface quality of such 3D printed articles is good, even with reinforcing agents, such as aramid fibers, as high as 30 wt%.
  • 3D printed articles comprising the AM compositions disclosed herein exhibit low moisture absorption, high modulus of elasticity, high tensile strength, high relative strength, and relatively high HDT, particularly when reinforced with glass and/or carbon fibers.
  • the ratio of wet: dry tensile moduli of elasticity of 3D printed articles is greater than or equal to 0.85, 0.90 or 0.95 and the ratio of wetdry maximum tensile strengths is greater than or equal to 0.85, 0.90, or 0.95.
  • 3D printed articles comprising the AM compositions disclosed herein exhibit a height displacement of less than 2 mm, preferably less than 1 mm, more preferably less than 0.5 mm, and most preferably less than 0.05 mm.
  • Compositions which exhibit low degrees of curl can be used to 3D print large, complex geometries with extrusion-based additive manufacturing systems such as FFF processes.
  • AM compositions disclosed herein can be produced by feeding the at least one semi crystalline copolyamide, the at least one amorphous copolyamide, the at least one aramid material, and any optional materials into a device designed to mix molten thermoplastics, such as a single or twin screw extruder, Banbury® mixer, Farrel Continuous Mixer (FCMTM), or a two- roll mill.
  • the materials are fed into the mixing device where the thermoplastic polymers are heated to a molten state, mixed with any optional materials such as reinforcing agents and/or other additives, extruded or removed from the mixing device and cooled to form the AM compositions.
  • the polyamide composition can be pelletized, granulated and/or extruded into filaments. Such processes are well known in the art.
  • Filaments, strands, or fibers for use in additive manufacturing processes, especially FFF processes may be formed by any method known in the art.
  • filaments disclosed herein may be prepared by the following process steps:
  • amorphous copolyamide, the at least one aramid material, and any optional materials are fed into an extruder in which the temperature of the extruder is sufficient to form a molten mixture;
  • filaments disclosed herein may be prepared by the following process step: 1) Semi-crystalline copolyamide, amorphous copolyamide, the at least one aramid material, and any optional materials are mixed at a temperature sufficient to form a molten mixture, the molten mixture is extruded through a die, and the extrudate is cooled to form a filament.
  • the AM compositions described herein may be used to prepare articles by additive manufacturing or 3 -dimensional (3D) printing techniques, especially by fused filament fabrication processes which preferably use filaments supplied from spools, and by pellet additive manufacturing processes, which preferably use pellets.
  • Fused filament fabrication is a process commonly used to prepare articles from filaments.
  • a filament comprising AM compositions disclosed herein, is fed through a heated die or nozzle wherein the temperature of the die is sufficiently high to melt the filament.
  • the molten filament exits the die and is deposited in a layer-by-layer fashion to form the desired article. Control of deposition rate may be varied by altering the filament feed rate.
  • a filament is unwound from a spool and fed to a heated nozzle, which can be turned on or off to control the flow and the temperature of the nozzle varied as needed.
  • a worm-drive or pair of profiled wheels pushes the filament into the nozzle at a controlled rate.
  • the nozzle heats the filament past its melting and/or glass transition temperature and the melted material/filament is deposited by a print head on a substrate to form a layer. Subsequent layers are deposited on top of the previous layer. After each layer is deposited, the position of the print head relative to the substrate is then incremented along a z-axis
  • the temperature of the melt is controlled such that the melted material solidifies substantially immediately (within several seconds) upon forming a layer on the base of the 3D printer, with the buildup of multiple layers to form the desired three-dimensional object.
  • extrusion-based AM processes including“pellet additive manufacturing” (PAM) and“big area additive manufacturing” (BAAM), utilize polymer pellets and powders, fiber reinforcements, and other fillers and additives as the feedstock instead of filaments with the additive manufacturing system combining melting, compounding, and extrusion functions, enabling stiff, highly reinforced materials to be printed.
  • PAM pellet additive manufacturing
  • BAAM big area additive manufacturing
  • 3D printed articles disclosed herein may be prepared by the following process steps for FFF :
  • 3D printed articles disclosed herein may be prepared by the following process steps for PAM:
  • PA1 PA 612/6T (85/15) having an inherent viscosity of 1.25-1.40 dl/g available from DuPont.
  • PA2 PA 6I/6T (70/30) having an inherent viscosity of 0.79-0.85 dl/g available from DuPont.
  • KP1 Kevlar® Powder having a particle size of 127 micron (dso, laser diffraction method) and a surface area of 0.59 m 2 /g.
  • KMP1 Kevlar® Micropulp having a weight-average length of 0.1-0.2 mm, a particle size of 54 micron (dso, laser diffraction method) and a surface area of 21.5 m 2 /g.
  • Relative strength was calculated according to Equation 1, wherein the tensile strength and percent elongation at break are each measured pursuant to ISO 527-2:2012.
  • Heat deflection temperature (HDT) values were determined according to ISO 75-2:2013 method B, using a flexural stress of either 66 psi (0.45 MPa) or 261 psi (1.8 MPa), as specified in the Examples. Bars with dimensions of 80 mm x 10 mm x 4 mm were either 3D-printed or prepared from injection-molded ISO 1 A MPB. All bars were tested either“dry-as-printed” or “dry-as-molded” unless specified otherwise.
  • Impact strength and impact energy were determined according to ISO 180:2000 method A (ISO 180/ A, notched Izod). Bars with dimensions of 80 mm x 10 mm x 4 mm were either 3D- printed or prepared from injection-molded ISO 1 A MPB. All bars were prepared“dry-as- printed” or“dry-as-molded” as specified in the examples, and measured without conditioning unless specified otherwise.
  • Curl Bar Test This test was adapted from US20140141 166 A1 and is used to measure the amount of curl in a 3D-printed test sample. Printing of the test samples is performed in a layer-by-layer manner using an extrusion-based additive manufacturing system as specified. For FFF, the test involves treating the entire bed of the 3D printer with a sheet of poly ether imide (PEI), commercially available from Aleph Objects, Inc.
  • PEI poly ether imide
  • a test bar from tool path instructions to ideally have a 270 m length, a 10 mm width, and a 10 mm vertical height using the following printer settings: 0.35 to 0.5 mm nozzle, 0.20 mm to 0.25 mm layer height, 100% 45/-4S degree infill, 1 shell, and 100% flow.
  • the nozzle and bed temperatures, printing speed, and cooling can be adjusted according to the material being printed.
  • a nozzle temperature of 275 °C, a bed temperature of 85 °C and a printing speed of 30 mm/sec were used, unless specified otherwise, with no cooling fan.
  • a light layer of glue stick (Elmer’s Washable Glue Stick) was applied prior to printing. After the test bar was printed, it was removed from the system and measured for curl at room temperature (25 C C). The curl of the material manifests itself by the ends of the test bar curling up, such that the test bar will bow or curl.
  • the curl measurement involves identifying a line that connects the ends of the test bar in the longest dimension and locating the midpoint along the length of the test bar between the ends. The amount of curl is then measured as the height of the displacement of the ends of the test bar measured from the line between the two ends of the test bar to the surface of the test bar at the midpoint. This height of the displacement may be measured with a micrometer and recorded in mm.
  • a line is drawn between the edge of the two ends in the lengthwise direction (longest direction) of the test bar.
  • the distance or height between the midpoint of the test bar in the lengthwise direction and the line created by the two ends of the test bar is the degree of curl in mm.
  • Temperature Range Test This test involves printing a single-wall cylinder with 0% infill and 0.2 mm or 0.25 mm layer height at various nozzle temperatures. A range of nozzle temperatures can be explored by varying the temperature with height. Software from Cura or Simplify3D may be used to run these tests; the use of this software for this test is easily within the capabilities of one skilled in the art.
  • the single-wall cylinder has a diameter of 40 mm and total vertical height of 120 mm, although the height may be varied to, for example, test a wider temperature range or accommodate finer step-changes in temperature.
  • Temperature ranges are as specified, e.g., from 295 °C to 190 °C with the temperature starting at the highest temperature and decreasing by 10 °C for every' 10-rnrn increase in height.
  • the cylinder is inspected using the unaided human eye for defects. Common defects include bubbles due to release of moisture, cracks in the cylinder wall, and unraveling of the printed strand due to poor interlayer adhesion, particularly at lower temperatures.
  • the temperature region in which the material for extrusion additive manufacturing can be printed into a 3D cylinder test sample without visible bubbles, cracks, delamination or other defects is recorded as the printing temperature range.
  • any temperature region in which a defect is observed is excluded from the temperature range, with the temperature range defined as the largest continuous region for which defects are not observed, as calculated in Equation 2, with T1 the highest temperature included in this region and T2 the lowest temperature included in this region, with temperatures measured in degrees Celsius. If the cylinder prints with defect-free walls at the highest attempted temperature, Tl is assigned as that temperature. If the cylinder prints with defect-free walls at the lowest attempted temperature, T2 is defined as that temperature.
  • compositions disclosed in the Examples into a Werner & Pfleiderer 30 mm twin screw extruder Barrel temperatures were set between 220-280 °C to ensure melting and adequate mixing.
  • the melt mixture was extruded through a die, quenched in a water bath at a temperature between 5- 60 °C, cut into pellets, and dried in a vacuum oven at 80 °C under a sweep of nitrogen overnight.
  • the dried pellets were sealed in aluminum moisture proof bags under vacuum before being used to produce filaments.
  • the dried pellets were fed into a 1.25 inch (32 mm) Brabender single- screw extruder. Barrel temperatures were set between 220-280 °C to achieve optimal filament quality depending on the specific polymer composition being processed.
  • the melt mixture coming out of the die was quenched in a water bath at a temperature between 5-60 °C to form a filament.
  • the filament was moved by a strand puller at a rate to prevent breakage and wound into spools.
  • Two diameters of filaments, 2.85 mm and 1.75 mm, were produced by adjusting the pulling rate. These filaments were used to print 3D articles of the Examples.
  • printers were used, as specified, for the examples described herein: (a) Lulzbot ® Mini and Lulzbot ® TAZ6 (Aleph Objects, Inc. Loveland, CO), each equipped with a hexagon direct-drive hot-end and 0.5 mm hexagon style nozzle and utilizing nominally 2.85 mm filament (b) Makergear M2 (Makergear, LLC; Beachwood, OH), equipped with a direct-drive hot-end and 0.35 mm nozzle and utilizing nominally 1.75 mm filament. Unless specified otherwise, properties across all examples and comparative examples within the same table are compared using the same printer/hot end/nozzle combination. Hardened- steel or abrasion- resistant nozzles were used when printing any composition comprising fillers.
  • Test bars can be tested in various directions including vertical, edge, or flat as shown in Figure 1 and are listed in the tables as bar type. All test bars were printed with a 45L-45 infill angle and 1 perimeter.
  • Tables 1 and 2 show the properties of various 3D-printed test samples prepared from AM compositions disclosed herein comprising blends of semi crystalline copolyamide A and amorphous copolyamide B with Kevlar ® powder and micropulp. All the test bars for the examples and comparative examples in tables 1 and 2 were printed on a Lulzbot Mini or Makergear M2 under a nitrogen-purged atmosphere at 30 mm/sec at a nozzle temperature of 275 °C and a bed temperature of 85 °C with no cooling fan. Tensile properties are reported for DAP ISO 5 A bars or DAM injection-molded ISO 1 A bars, with the exceptions of the printed 5 A bars of E3 and E9, which were conditioned.
  • Curl was measured according to the Curl Bar Test with the bars printed on a Makergear M2.
  • print temperatures ranged from 295 - 220 °C, stepping down the temperature by 5 °C in 10 mm increments while printing a hollow cylinder according to the Temperature Range Test.
  • Printing speed was 30 mm/sec with no fan and a Lulzbot TAZ6 or Lulzbot Mini used as the printer.
  • Table 1 shows the properties of various 3D printed and injection molded test samples prepared from AM compositions disclosed herein comprising 10 wt. % to 30 wt. % of KP1 (Examples El to E6).
  • Comparative Examples Cl to C3 are AM compositions comprising PA1 and P A2 without KP 1.
  • Examples El to E6 whether prepared by IM or 3D printed, show higher tensile modulus, comparable tensile strength, and lower strain at break compared to Cl to C3.
  • HDT of E4 is more than 30 °C higher than the HDT of C3 (both prepared by IM).
  • 3D printed samples El to E3 maintain at least 70 % of the tensile strength, tensile modulus, and impact strength.
  • Comparison of conditioned example E3 with DAP example El demonstrates that mechanical properties are not adversely compromised due to the presence of moisture.
  • the ratio of wefidry tensile moduli is 0.85 and the ratio of wefidry tensile strengths is 1.02.
  • AM compositions comprising semi-crystalline polyamide A and amorphous polyamide B are compatible with Kevlar® powder over a broad composition range as exemplified in El to E6.
  • the printability of these compositions indicates that Kevlar powder is well dispersed in the polyamide matrix at particle sizes below the 3D printer nozzle size ( ⁇ 0.35 mm).
  • the narrow particle size distribution of the Kevlar ® powder and good compatibility with polyamide matrices provides both good printability and part performance.
  • Table 2 shows the properties of various 3D-printed and injection-molded test samples prepared from AM compositions disclosed herein comprising 10 wt.% to 30 wt.% of Kevlar ® micropulp KMP1 (Examples E7-E12). Compared with Cl to C3, Examples E7 to E12 show significantly higher tensile modulus (1.5-2 times higher), higher tensile strength (30% to 80% higher (except E8), and comparable or slightly lower strain at break. Examples E8 and E10-E12 show that inclusion of Kevlar ® micropulp (KMP1) in the polyamide blends provides significant improvement in HDT (from 31 °C in E12 to 83 °C in El l).
  • KMP1 Kevlar ® micropulp
  • 3D-printed samples E7-E9 maintain over 70% of the tensile strength, tensile modulus, and strain at break. Impact strength of 3D-printed Example E8 is higher than injection-molded examples E10-E12.
  • Example E9 Comparison of conditioned Example E9 with DAP Example E7 demonstrates that the mechanical properties are not adversely compromised due to the presence of moisture.
  • the ratio of wetdry tensile moduli is 1.08 and the ratio of wetdry tensile strengths is 0.97.
  • Kevlar ® micropulp is compatible with polyamide blends comprising semi-crystalline polyamide and amorphous polyamide over a broad composition range as exemplified in E10 to E12.
  • Tables 1 and 2 demonstrate that the AM compositions disclosed herein comprising aramid powders and micropulps can be 3D printed by FFF to produce articles having balanced mechanical properties close to injection molding results.

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Abstract

L'invention concerne des compositions pour fabrication additive comprenant : A) de 5 à 94,9 pour cent en poids d'au moins un copolyamide semi-cristallin possédant un point de fusion ; ledit copolyamide semi-cristallin comprenant : a-1) de 5 à 40 pour cent en moles de motifs répétés aromatiques dérivés : i) d'un ou de plusieurs acides dicarboxyliques aromatiques comportant de 8 à 20 atomes de carbone et d'une diamine aliphatique comportant de 4 à 20 atomes de carbone ; et a-2) de 60 à 95 pour cent en moles de motifs répétés aliphatiques dérivés : ii) d'un acide dicarboxylique aliphatique comportant de 6 à 20 atomes de carbone et d'une diamine aliphatique comportant de 4 à 20 atomes de carbone ; B) de 5 à 94,9 pour cent en poids d'au moins un copolyamide amorphe comprenant : b-1) de 60 à 90 pour cent en moles de motifs répétés aromatiques dérivés : iii) de l'acide isophtalique et d'une diamine aliphatique comportant de 4 à 20 atomes de carbone ; et b-2) de 10 à 40 pour cent en moles de motifs répétés aromatiques dérivés : iv) de l'acide téréphtalique et d'une diamine aliphatique comportant de 4 à 20 atomes de carbone ; C) de 0,1 à 50 pour cent en poids d'au moins un matériau aramide ; et d) de 0 à 30 pour cent en poids d'au moins un additif. Ces compositions fournissent des articles imprimés 3D présentant des propriétés physiques améliorées.
PCT/US2019/026006 2018-04-06 2019-04-05 Compositions pour fabrication additive WO2019195689A1 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112322029A (zh) * 2020-11-19 2021-02-05 广东聚石科技研究有限公司 一种无卤阻燃尼龙材料及其制备方法和应用
CN114231022A (zh) * 2021-12-10 2022-03-25 杭州晟天新材料科技有限公司 适用于fdm型3d打印的尼龙复合材料及其制备方法
EP4316781A1 (fr) 2022-08-01 2024-02-07 Arkema France Procédé de fabrication d'un article par impression par extrusion additive de matériau à l'aide d'un modificateur de rhéologie

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CN112322029A (zh) * 2020-11-19 2021-02-05 广东聚石科技研究有限公司 一种无卤阻燃尼龙材料及其制备方法和应用
CN114231022A (zh) * 2021-12-10 2022-03-25 杭州晟天新材料科技有限公司 适用于fdm型3d打印的尼龙复合材料及其制备方法
EP4316781A1 (fr) 2022-08-01 2024-02-07 Arkema France Procédé de fabrication d'un article par impression par extrusion additive de matériau à l'aide d'un modificateur de rhéologie
WO2024028326A1 (fr) 2022-08-01 2024-02-08 Arkema France Procédé de fabrication d'un article par impression par extrusion additive de matériau à l'aide d'un modificateur de rhéologie

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