TECHNICAL FIELD

[0001] This disclosure relates to grafted and copolymers of aliphatic polyketones and methods to form them for use in additive manufacturing. In particular, the method involves the grafting of functional groups, such as grafting oligomers or polymers having an alcohol, thiol or amine into the polymer chain of the aliphatic poly ketone for use in additive manufacturing.

BACKGROUND

[0002] Various additive manufacturing processes, also known as three-dimensional (3D) printing processes, can be used to form three-dimensional objects by fusing or adhering certain materials at particular locations and/or in layers. Material can be joined or solidified under computer control, for example working from a computer-aided design (CAD) model, to create a three-dimensional object, with material, such as liquid molecules, extruded materials including polymers, or powder grains, which can be fused and/or added in various ways including layer- by-layer approaches and print head deposition approaches. Various types of additive manufacturing processes include binder jetting, directed energy deposition, material extrusion, material jetting, powder bed fusion, sheet lamination, vat photopolymerization, and fused filament fabrication.

[0003] Illustratively, fused filament fabrication (FFF) is an additive manufacturing process that employs a continuous filament that may include one or more thermoplastic materials. The filament is dispensed from a coil through a moving, heated extruder printer head, and deposited from the printer head in three dimensions to form the printed object. The printer head moves in two dimensions (e.g., an x-y plane) to deposit one horizontal plane, or layer, of the object being printed at a time. The printer head and/or the object being printed moves in a third dimension (e.g., a z-axis relative to the x-y plane) to begin a subsequent layer that adheres to the previously deposited layer and further described in U.S. Pat. Nos. 5.121,329 and 5,503,785. Because the technique requires melting of a filament and extrusion, the build materials (“build polymer”) have been limited to thermoplastic polymers. Typically, the thermoplastic polymers that have been most successfully printed by the FFF method arc aliphatic polyamides (c.g., Nylon 6,6) and polyesters such as polylactic acid (PLA).

[0004] The FFF method to make complex parts that may have unsupported members require the use of a removable support material (“support polymer or support material”) that is extruded from a separate print extrusion nozzle that supports the “build material or build polymer”. Typically, the support materials have been comprised of polymers that were dissolved in water such as described in US Pat. Nos. 6,790,403; 7,754,807; 8,822,590; and 10,100,168. In US Pat. No. 5,503,785 an interface layer between the support polymer and build polymer that was water dissolvable was used to allow the breaking away of the support material. More recently, breakaway support materials (polyethersulfone polymer blends and polyphenylene) for supporting particular high temperature build polymers such as polyetherimides and polyetherketones have been described in US Pat. No. 10,059,053 and US Pat. Publ. No. 2020/00189181. However, in many instances the production of such parts are limited by the compatibility of the build and support material. Likewise, the ability to create parts having more than one build material is limited due to compatibility issues between each of the materials. [0005] Likewise, powder-based methods of additive manufacturing include the following. Selective laser sintering (SLS) is a 3D-printing technique that uses a laser to fuse powder material in successive layers (see, for example, U.S. Pat. No. 5,597,589). High-speed sintering (HSS) and multi-jet fusion (MJF) 3D-printing employ multiple jets that similarly deposit successive layers of infrared-absorbing (IR-absorbing) ink onto powder material, followed by exposure to IR energy for selective melting of the powder layer. Electrophotographic 3D-printing employs a rotating photoconductor that builds the object layer-by-layer from the base.

[0006] Selective laser sintering (SLS), multi-jet fusion (MJF), and high-speed sintering (HSS) 3D-printing methods use the same type of free-floating, non-fixed powder bed. They generally have the same material requirements for compatibility with the printing process since the additively built object will experience similar stresses, only with different heating mechanisms to obtain the melt phase. If the residual stress is too high, the object will deform or be deformed beyond acceptable tolerances.

[0007] The residual stresses have typically been minimized for these powder bed-based 3D printers by using crystalline or semicrystalline thermoplastic polymers having sufficiently large window between its melting temperature and its recrystallization temperature. Unfortunately, this has limited the polymers that have successfully used to print large or complex parts using SLS and MJF methods (e.g., polyamides), thus limiting the use of these additive manufacturing methods as well as these methods typically employing the same polymeric powder throughout the part. Likewise, the use of semi-crystalline polymers upon recrystallization after heating to make the additive manufactured article may limit the properties of the articles produced.

[0008] Accordingly, it would be desirable to provide a thermoplastic polymer that may be tailored to form additive manufactured articles with gradient compositions, char acteristics and matched processing during the formation of the additive manufactured article.

SUMMARY

[0009] It has been discovered that grafted aliphatic polyketones (GAPs) may be particularly useful for making additive manufactured articles. The GAPs may be useful as a build material or support material depending on the type and extent of the grafting. The GAPs may be tailored to be useful as compatibilizers when making articles of differing polymers. The grafting maybe used to inhibit cross-linking of the GAPs through the carbonyl during the additive manufacturing process, for example, due to steric hindrance introduced by the grafted moities. An illustration is an additive manufactured article comprising at least two layers of a GAP adhered together. Another illustration is a filament comprised of a GAP. A further illustration is a powder comprised of a grafted aliphatic polyketone and having a D90 particle size of at most 300 micrometers and average particle size of 1 micrometer to 150 micrometers equivalent spherical diameter. The filament and powder may be useful for additive manufacturing.

DESCRIPTION OF THE DRAWING

[001] Figure 1 is a plot of a differential scanning calorimetry (DSC) plot of an aliphatic polyketone useful to make the grafted aliphatic polyketone of this invention.

[002] Figure 2 is a DSC plot of a grafted aliphatic polyketone powder of this invention. [003] Figure 3 is a DSC plot of a grafted aliphatic polyketone powder of this invention.

DETAILED DESCRIPTION

[0010] While the disclosure has been described in connection with certain embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law. [0011] The additive manufactured article may be an additive manufactured article wherein the GAP is a support material for a build material. Support material herein refers to material that supports sections of a manufactured article such as in FFF methods that are subsequently removed after the pail is made and the build material has solidified sufficiently to support itself. Illustratively, the GAP may have a sufficient amount of polar groups grafted thereto to render the GAP water soluble (amine, hydroxyl, carboxylic acid, or thio group) allowing the removal from the printed article by dissolution in water, such as described by U.S. Pat. Nos. 5,071,926;

5,955,563 and 6,214,941, each incorporated herein by reference. In a particular a particular illustration, an ungrafted aliphatic polyketone may be grafted as described in the aforementioned patents and used as the support material for a build material comprised essentially of the same ungrafted aliphatic polyketone used to form the GAP.

[0012] The additive manufactured article may comprised of a GAP having one or more cyclic groups grafted in the backbone of the GAP through 1, 4-dicarbonyl moieties present in the ungrafted aliphatic polyketones such as those described below comprised of copolymers of ethene, propene and carbon monoxide, which can be converted into thiophene, furan and pyrrole such as described in WO 1998/042770; US6225419; J.Pol.Sci.Pol.Chem. 1994, 32, 841 and Journal of Polymer Science: Part A. Polymer Chemistry, Vol. 32,84-&17 (1994) each incorporated herein by reference.

[0013] Illustratively, the GAP having the cyclic group therein may be illustrated by wherein each R’ is independently H or a methyl group, R is a hydrocarbyl group having a molecular weight of 10 Da to 1 mega Da, and n + y is an amount where the grafted polyketone has a molecular weight 1000 Da to 2 MDa, n/b is from 0.001 to 99.999, A is the saturated residue of alkene monomer having m carbons where m is from 2 to 12, 8, 6, 4 or 3. Desirably, m is 2 and 3, with the ratio being as described below for x/y for the terpolymer of CO, propylene and ethylene.

[0014] The molecular weight (i.e., n + y) may desirably be an amount wherein the molecular weight is at least 10,000, 50,000, or 100.000 Da to 1 MDa, 0.5 MDa or 0.2 MDa. R may be hydrocarbyl that is substituted or unsubstituted. Hydrocarbyl as used herein refers to a group containing one or more carbon atom backbones and hydrogen atoms, which may optionally contain one or more heteroatoms. Where the hydrocarbyl group contains heteroatoms, the heteroatoms may form one or more functional groups well known to one skilled in the art (e.g., thiol, hydroxy, amine or salts such as metal or ammonium salts). Hydrocarbyl groups may contain cycloaliphatic, aliphatic, aromatic, or any combination of such segments. The aliphatic segments can be straight or branched. The aliphatic and cycloaliphatic segments may include one or more double and/or triple bonds. Included in hydrocarbyl groups are alkyl, alkenyl, alkynyl, aryl, cycloalkyl, cycloalkenyl, alkaryl, and aralkyl groups. For example, R may be a polymeric chain such as a polycarbonate, polyolefin, polystyrene, polyarylsulfone, polyester, polyamide, polyimide or combination thereof.

[0015] The ratio n/b may vary over a wide range depending on the desired characteristics of the GAP polymer. Illustratively, it may be useful for n/b to be low (e.g., less than 1, 0.5 or 0.1) to realize a desired water solubility, when forming a support material and alternatively it may be desired to have a high n/b (greater than 1, 2 or 10) when forming a build material. Exemplary n/b ratio ranges for particular applications may be 0.001 or 0.01 to 0.1; 99.999 to 90, 95, 99 or 99.9; or 0.1 to 10.

[0016] The grafted aliphatic polyketones is formed from an ungrafted aliphatic polyketone that may be formed by reacting carbon monoxide and an alkene monomer, typically in the presence of a group 8 to 10 transition metal catalyst. In particular, the method may be any one of those described in US Pat. Nos. 4,835,250; 4,894,435 and 5,138,032 and US Pat. Publ. No. 2008/0058494 each incorporated by reference in its entirety. In particular, the method, reaction conditions and monomers are those described in US Pat. No. 5,138,032 from col. 2 line 52 to col. 5, line 17 specifically incorporated herein by reference.

[0017] Desirably, the alkene monomer is comprised of an olefin having from 2 to 12, 8 or 6 carbons. Illustratively, the alkene monomer is ethylene or the alkene monomer comprises ethylene and at least one other olefin monomer such as propylene. When the polyketone is a copolymer of ethylene and another olefin monomer (e.g., propylene), the amount of ethylene and other olefin may be as described in US Pat. No. 5,138,032 from col. 2, line 17 to col. 3, line 14. [0018] The GAP may be one that converts one or more carbonyl group of the ungrafted aliphatic polyketones described below directly into a hydrocarbyl group as described above. For example, the carbonyl may be, for example, converted to an alcohol, thiol, or acetal, such as described by U.S. Pat. Nos. 2,495,293; 5,071,926; 5,091,486; and Polymer Science: Part A. Polymer Chemistry, Vol. 32,84-&17 (1994), incorporated herein by reference. It is noted, that the grafted polymer may have both cyclic groups (e.g., thiophene, furan and pyrrole groups within the backbone of the GAP) such as described above and directly converted carbonyl groups.

[0019] Illustratively, the GAP having directly converted carbonyl groups therein may be illustrated by wherein each R ² is independently OH, SH, amine or salt, and n + z is an amount where the grafted polyketone has a molecular weight of 1000 Da to 2 MDa, n/z is from 0.001 to 99.999, A is the saturated residue of alkene monomer having m carbons where m is from 2 to 12.

[0020] The molecular weight (i.e., n + z) may desirably be an amount wherein the molecular weight is at least 10,000, 50,000, or 100,000 Da to 1 MDa, 0.5 MDa or 0.2 MDa. R ² is desirably -OH, -NH2, -NRH or -NR2, where R has the same meaning as described above.

[0021] The ratio n/z may vary over a wide range depending on the desired characteristics of the GAP polymer. Illustratively, it may be useful for n/z to be low (e.g., less than 1, 0.5 or 0.1) to realize a desired water solubility, when forming a support material and alternatively it may be desired to have a high n/z (greater than 1, 2 or 10) when forming a build material. Exemplary n/z ratio ranges for particular applications may be 0.001 or 0.01 to 0.1 ; 99.999 to 90, 95, 99 or 99.9; or 0.1 to 10.

[0022] The ungrafted aliphatic polyketone used to make the grafted aliphatic polyketone may be illustrated by

[0023] where A is the residue of an alkene monomer converted to a saturated hydrocarbon group, m is from about 1 to 6 and n is at least about 2 to any practicable amount to realize the desired number average molecular weight useful in the invention. Exemplary useful number average molecular weights may be those that provide melting temperatures from about 175 °C or 210 °C to about 270 °C or 300 °C and may be from about 1000 to 250,000 or about 10,000 to 200,000 g/mole.

[0024] The ungrafted aliphatic polyketone desirably is one that is a terpolymer of carbon monoxide, ethylene and another alkene monomer (e.g., olefin of 3 to 12, 8 or 6 carbons and in particular propylene). Such ungrafted polyketone may be illustrated by random repeating units:

[0025] Where G is the saturated residue of an olefin of 3 to 12, 8 or 6 carbons polymerized through the double bond and x/y is at least 2 to 100 or 50 or 20. Desirably, G is propylene. The polyketone may be terminated by any useful group such as alkyl group, hydroxyl, ester, carboxylic acid, ether or combination thereof. The particular terminating group may arise from using a solvent such as a low molecular alcohol such as methanol or water or combination thereof.

[0026] When making the additive manufactured article comprised of the GAP any useful method may be employed such as described above. Illustratively, the GAP may be a powder having a particle size and size distribution that is useful for making additive manufactured articles and typically have an average or median particle size (D50), by volume, from about 1 micrometer (pm), 10 pm, 20 pm, 30 pm or 40 pm to 150 pm, 125 pm, 110 pm or 100 pm. Likewise, to enable consistent heating and fusion of the powder, it desirably has a D90 of at most 300 pm, 200 pm or 150 pm. To aid in flowability the polyketone desirably has a Dio of at least 0.1 pm, 0.5 pm or 1 pm by volume. D90 means the particle size (equivalent spherical diameter) in the particle size distribution, where 90% by volume of the particles are less than or equal to that size; similarly, D50 means the particle size (equivalent spherical diameter) in the particle size distribution, where at least 50% by volume of the particles are less than that size, and Dio means the particle size (equivalent spherical diameter) in the particle size distribution, where at least 10% by volume of the particles are less than that size. The particle size may be determined by any suitable method such as those known in the art including, for example, laser diffraction or image analysis of micrographs of a sufficient number of particles (-100 to -200 particles). A representative laser diffractometer is one produced by Microtrac such as the Microtrac S35OO. [0027] The GAP powder may be realized by any suitable method such as those known in the art including, but not limited to, milling at a temperature where the semicrystalline polyketone becomes embrittled may be used and is commonly referred to as cryomilling. Generally, the temperature for cryomilling may be any temperature below about 0 °C, -25 °C, -50 °C to about - 75 °C, -100 °C, -150 °C, or -190 °C. In an embodiment, the cooling is provided by using dry ice or liquid nitrogen. These powders, because of the size reduction process may have a decreased flowability and circularity, but nevertheless may be used to form desirable additive manufactured articles when used with processing aids known in the ail such as flow aids.

[0028] The GAP may be formed into various forms useful in various 3D printing methods such as fused filament fabrication methods. For example, the GAP may be formed into pellets, one or more rods, that can be fed into a fused filament fabrication method to print an object. Such pellets, rods, may be fed into an extruder where the GAP is further formed into a filament. The filament can be dimensioned in cross-section shape, diameter, and length for use in various fused filament fabrication methods to print various objects using va ious print heads. The filament can be formed as it is being used in a printing process or the filament can be pre-formed and stored for later use in a printing process. The filament may be wound upon a spool to aid in storage and dispensing. The filament can be formed in various ways, including various extrusion methods using various dies, such as hot extrusion and cold extrusion methods.

[0029] The fused filament fabrication method may employ material extrusion of the GAP to print items, where a feedstock of the GAP is pushed through an extruder. The filament can be employed within the three-dimensional printing apparatus or system in the form of a filament wound onto a spool. The three-dimensional printing apparatus or system can include a cold end and a hot end. The cold end can draw the filament from the spool, using a gear- or roller-based feeding device to handle the filament and control the feed rate by means of a stepper motor. The cold end can further advance the filament feedstock into the hot end. The hot end can include a heating chamber and a nozzle, where the heating chamber includes a liquefier, which melts the filament to transform it into a thin liquid. This allows the molten GAP to exit from a nozzle to form a thin, tacky bead that can adhere to a surface to which it is deposited upon. The nozzle may have any useful diameter and typically depending on resolution desired has a diameter of between 0.1 or 0.2 mm to 3 mm or 2 mm. Different types of nozzles and heating methods are used depending upon the GAP, the object to be printed, and the desired resolution of the printing process.

[0030] The GAP may include further additives useful in additive manufacturing. The compositions of this invention may further comprise useful additives such as those known in the art for making articles such as additive manufactured articles. For example, the GAP may have one or more of an ultraviolet (UV) stabilizer, filler, lubricant, plasticizer, pigment, flow aid, flame retardant, or solvent. Desirably, the GAP is essentially free of solvent (i.e., at most a trace amount, which may be at most 10 parts per million (ppm) by weight of the composition, 1 ppm). The amount of any particular additive may be any useful amount to realize a particular property for printing or characteristic of the article formed therefrom. Generally, the amount of the additive or additives, when present, is at most about 50%, 25%, 10% or 5% by volume of the GAP and any other additive. The flow aid may be any known compound for improving the flowability of powders with fumed silica being an example (e.g., Aerosil 200).

[0031] The filler may be any useful filler such as those known in the art. Examples of the filler ceramics, metals, carbon (e.g., graphite, carbon black, graphene), polymeric particulates that do not melt or decompose at the printing temperatures (e.g., cross-linked polymeric particulates, vulcanized rubber particulates and the like), plant-based fillers (e.g., wood, nutshell, grain and rice hull flours or particles). Exemplary fillers include calcium carbonate, talc, silica, wollastonite, clay, calcium sulfate, mica, inorganic glass (e.g., silica, alumino-silicate, borosilicate, alkali alumino silicate and the like), oxides (e.g., alumina, zirconia, magnesia, silica “quartz”, and calcia), carbides (e.g., boron carbide and silicon carbide), nitrides (e.g., silicon nitride, aluminum nitride), combinations of oxynitride, oxycarbides, or combination thereof. In certain embodiments, the filler comprises an acicular filler such as talc, clay minerals, chopped inorganic glass, metal, or carbon fibers, mullite, mica, wollastanite or combination thereof. In a particular embodiment, the filler is comprised of talc.

[0032] The additive article may also be comprised of other polymers such as commonly used in additive manufacturing such as a thermoplastic polymer powder useful for additive manufacturing such as polyamides (e.g., Nylon 6; Nylon 6,6; Nylon 4,6; Nylon 6,9; Nylon 5,10; Nylon 6,10; Nylon 11; Nylon 6,12 and Nylon 12), polycarbonate, polyolefin, polystyrene, polyarylsulfone, polyester, polyamide, polyimide or combination thereof. The amount of other polymer may be any useful amount. Illustratively, the additive manufactured article may have an amount of GAP polymer from 1% to 5% by volume of the total amount of polymers, when the GAP is used primarily as a compatibilizer for two or more other thermoplastic polymers. In other illustrations depending on the characteristics desired, the GAP may be from 5%, 10%, 25%, 50% to 99%, 95%, 90% or 80% by volume of the polymers present in the additive manufactured article.

EXAMPLES

Example 1:

[0033] Aliphatic polyketone powder is made by a process in the manner described in U.S. Pat. No 5,138,032 from col. 2 line 52 to col. 5, line 17. The DSC plot is shown in Figure 1. The powder is used directly from the reactor. The thermal properties are determined according to ASTM D3418 at a heating and cooling rate of 20 °C/minute.

[0034] One gram of GRILAMID EMS L16 “PA 12” polyamide (EMS-Grivory) is dissolved in NMP (N-methylpyrrolidone) at 130 to 150 °C. Upon complete dissolution of the polyamide, 9 grams of the aliphatic polyketone is added and dissolved. Upon complete dissolution, the solution is cooled to about 100 °C. At this temperature, deionized water is added forming a thick slurry of grafted aliphatic poly ketone particles. The water is added until no further precipitation is observed. The particles are filtered and rinsed with further water to remove the NMP. The grafted aliphatic polyketone displayed the thermal characteristics shown in Figure 2. Examplc 2:

[0035] Example 1 is repeated except that GRILAMID TR90 amorphous nylon is used in place of the of the PA 12 used in Example 1. The thermal characteristics is shown in Figure 3. Example 3 :

[0036] Example 1 is repeated except that the polyketone prior to being dissolved is melt extruded (-240 °C) to form pellets. The thermal characteristics are similar to those in Example 1.

Example 4:

[0037] Example 2 is repeated except that the poly ketone prior to being dissolved is melt extruded (-240 °C) to form pellets. The thermal characteristics are similar to those in Example 2.