Polymer filaments for additive manufacturing having reduced emissions

Abstract

To provide polymer filaments compatible with fused filament fabrication, capable of reducing volatile organic compound (VOC) emissions while 3D printing.SOLUTION: Polymer filaments comprise a thermoplastic polymer and a bio-based additive; the bio-based additive is admixed with the thermoplastic polymer in an effective amount to decrease total volatile organic compound (TVOC) emissions under additive manufacturing conditions, as determined by gas chromatography and measured relative to the thermoplastic polymer alone, by at least about 10% on a weight basis. Methods for forming a polymer filament compatible with fused filament fabrication may comprise: forming a melt blend comprising a thermoplastic polymer and a bio-based additive; and extruding the melt blend and cooling to form a polymer filament comprising the bio-based additive admixed with the thermoplastic polymer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates, in general, to additive manufacturing, and more specifically to polymer filaments suitable for molten filament manufacturing that reduces the emissions of volatile organic compounds (VOCs) during printing. [Background technology]

[0002] Additive manufacturing, also known as three-dimensional (3D) printing, is a rapidly growing field of technology. While traditionally used in rapid prototyping activities, this technique is increasingly being adopted to manufacture commercial and industrial parts of any number of complex shapes. The additive manufacturing process typically involves building parts layer by layer, for example, by 1) depositing a flow of molten printing material obtained from a continuous filament, or 2) sintering powder particles of printing material using a laser. Layer by layer deposition is usually computer-controlled, depositing the printing material in precise locations based on a digital three-dimensional "blueprint" of the part to be manufactured, and forming the printed part through densification of the printing material carried out in conjunction with the deposition. The printing material that forms the body of the printed part may be referred to herein as the "build material."

[0003] The additive manufacturing process that uses a flow of molten printing material to form parts is sometimes called the "molten deposition modeling" process or the "molten filament manufacturing" process. The molten printing material is formed by heating thermoplastic polymer filaments, which are then deposited layer by layer and bonded together to form compacted parts with a specific shape. Other additive manufacturing techniques rely on heating to compact polymer microparticles and include, for example, powder bed fusion (PBF), selective laser sintering (SLS), electron beam melting (EBM), binder injection and multi-jet fusion (MJF), vat photopolymerization, and directed energy deposition.

[0004] As additive manufacturing technologies become increasingly prevalent in commercial, educational, and home environments, there is a growing focus on enhancing operational safety. One problem that can be encountered in these technologies is the generation of volatile organic compounds (VOCs), particularly when printing materials such as polymer filaments, polymer microparticles, or polymer sheets are heated to their softening temperature for compaction, at least during the processes of extrusion, printing, additive manufacturing, and similar processes. Thermoplastic polymers containing styrene or acrylic monomer units, such as poly(acrylonitrile-butadiene-styrene) (ABS), can release particularly harmful VOCs. To mitigate potential health impacts, additive manufacturing units can be fitted with air filters and / or operated in ventilated workspaces. However, these measures are cumbersome and not applicable in all environments. [Overview of the Initiative]

[0005] This disclosure relates to a bio-based additive for reducing VOC emissions during additive manufacturing, and to a method for producing a printing material containing the bio-based additive.

[0006] In some embodiments, a polymer filament suitable for molten filament manufacturing comprises a thermoplastic polymer and a bio-based additive mixed with the thermoplastic polymer in an amount effective in reducing total volatile organic compound (TVOC) emissions by at least about 10% by weight under additive manufacturing conditions, as determined by gas chromatography and measured relative to the thermoplastic polymer alone.

[0007] In some embodiments, a method for forming a polymer filament suitable for molten filament manufacturing comprises forming a molten mixture containing a thermoplastic polymer and a bio-based additive, and extruding and cooling the molten mixture to form a polymer filament containing a bio-based additive mixed with the thermoplastic polymer, wherein the bio-based additive is present in an amount effective, as determined by gas chromatography and measured relative to the thermoplastic polymer alone, to reduce total volatile organic compound (TVOC) emissions by at least about 10% on a weight basis under additive manufacturing conditions.

[0008] In some embodiments, the additive manufacturing process includes providing a polymer filament comprising a thermoplastic polymer and a bio-based additive mixed with the thermoplastic polymer in an amount effective in reducing total volatile organic compound (TVOC) emissions by at least about 10% on a weight basis under additive manufacturing conditions, as determined by gas chromatography and measured for the thermoplastic polymer alone; heating the polymer filament to a temperature above the softening temperature of the thermoplastic polymer to form a softened polymer material; and depositing the softened polymer material layer by layer to form a printed part. [Brief explanation of the drawing]

[0009] The following figures are included to illustrate specific aspects of the disclosure and should not be viewed as exclusive embodiments. The disclosed subject matter may be subject to reasonable modifications, alterations, combinations, and equivalents in form and function that are conceivable to those skilled in the art and are in the interest of the disclosure.

[0010] [Figure 1] This is an illustrative diagram of a fused filament manufacturing process for producing printed parts using build material and removable support material.

[0011] [Figure 2] This is a diagram of an exemplary printed part having a protruding portion.

[0012] [Figure 3A] TEM images of comparative examples and examples of the present disclosure are shown. [Figure 3B] TEM images of comparative examples and examples of the present disclosure are shown. [Figure 3C] TEM images of comparative examples and examples of the present disclosure are shown. [Modes for carrying out the invention]

[0013] This disclosure relates, in general, to additive manufacturing, and more specifically to polymer filaments suitable for molten filament manufacturing that reduces the emissions of volatile organic compounds (VOCs) during printing.

[0014] Additive manufacturing is a growing field of technique that can utilize a wide variety of powder, particulate, and filament-based printing materials. While the number of available printing materials is rapidly expanding, the range of suitable polymers remains limited compared to the range available for competing manufacturing technologies such as injection molding. As use in commercial, educational, and home environments increases, environmental hygiene and safety associated with the additive manufacturing process are becoming increasingly important. Because the additive manufacturing process can heat polymer raw materials to degradation boundary temperatures during deposition and compaction, the emission of aerosolized particulate matter and volatile organic compounds (VOCs) has recently become a concern. While VOC and particulate emissions can be addressed with adequate ventilation and filtering, this can sometimes be cumbersome or costly. Furthermore, operators may not be aware that such safety measures are necessary for certain printing materials, and in non-industrial environments, ventilation may not be economically feasible, making air quality monitoring and control more difficult.

[0015] This disclosure demonstrates that by including one or more bio-based additives within a polymer filament, VOC emissions can be surprisingly reduced during additive manufacturing, such as during fused filament fabrication. Without being bound by any particular theory, the bio-based additives are thought to provide a carbon source that can effectively encapsulate VOCs and reduce their release into the surroundings. Advantageously, suitable bio-based additives can include various bio-waste streams that would otherwise be discarded in landfill or require time-consuming biorecycling operations such as composting and that are discharged in large quantities from manufacturing processes. Suitable bio-based additives can include, for example, coffee grounds and / or used brewer's grains. By incorporating such bio-based additives into polymer filaments suitable for additive manufacturing, the environmental impact of the additive manufacturing process can be improved and a step can be taken towards a circular economy and more efficient use of resources. As yet another advantage, polymer filaments with bio-based additives in combination therewith can continue to expand the breadth of polymer materials available for use in various additive manufacturing processes.

[0016] The terms used in the description and claims of this specification have their plain and ordinary meaning, except when modified by the following description.

[0017] As used herein, the term "thermoplastic polymer" refers to a polymeric material that softens and hardens reversibly upon heating and cooling. Thermoplastic polymers include thermoplastic elastomers.

[0018] As used herein, the term "total volatile organic compounds" (TVOC) is used to describe a group of organic compounds present in atmospheric emissions or ambient air. TVOC is the sum of the contributions of various types of organic compounds emitted from a sample, and as organic substances, typically have a boiling point of about 0 °C to about 100 °C and a carbon number of less than 6 for very volatile organic compounds (VVOC), a boiling point of about 100 °C to about 260 °C and a carbon number in the range of 6 to 16 for volatile organic compounds (VOC), and a boiling point of about 260 °C to about 400 °C and a carbon number of 16 or more for semi-volatile organic compounds (SVOC).

[0019] Unless otherwise specified, the melting point of the thermoplastic polymer is determined by ASTM E794-06(2018) at a heating and cooling rate of 10 °C / min.

[0020] Unless otherwise specified, the softening temperature or softening point of the thermoplastic polymer is determined by ASTM D6090-17. The softening temperature can be measured using a cup and ball apparatus available from Mettler-Toledo with a 0.50 gram sample at a heating rate of 1 °C / min.

[0021] The VOC emissions from the polymer filaments and additive manufacturing processes disclosed herein can be determined using any suitable technique for detecting emissions from materials and products. In one method, VOCs can be detected by gas chromatography and / or mass spectrometry, during which the VOCs can be measured under heating conditions that simulate the additive manufacturing conditions used to promote densification of the part. For example, to determine VOCs, the sample can be heated from 230 °C to 260 °C at a heating rate of 3 °C / min, the volatile substances can be collected, and analyzed over this temperature range. The data obtained is reported as total TVOC in μg per gram of sample.

[0022] Other suitable methods for measuring VOC emissions include ASTM D5116-17 and UL 2904 - “Method for Testing and Assessing Particle and Chemical Emissions from 3D Printers.” Instruments that can be used to measure TVOCs include any suitable system for quantifying volatile organic compounds such as halocarbons, alcohols, terpenes, aldehydes, ketones, ethers, and siloxanes. Examples of test systems include, but are not limited to, liquid chromatography-mass spectrometry (LC-MS), gas chromatography-mass spectrometry (GCMS), liquid chromatography by tandem mass spectrometry (LC / MS / MS), gas chromatography by tandem mass spectrometry (GC / MS / MS), high-performance liquid chromatography by tandem mass spectrometry (HPLC-LC / MS / MS), and gas chromatography by tandem mass spectrometry in electron capture negative ionization mode (GC / MSECNI).

[0023] Before discussing the various aspects of this disclosure in more detail, we first provide a brief consideration of the additive manufacturing process, in particular the molten filament manufacturing process, so that the features of this disclosure may be better understood. Figure 1 is a schematic diagram of an exemplary molten filament manufacturing process for producing parts using build material and removable support material. As shown in Figure 1, the print head 100 includes a first extruder 102a and a second extruder 102b, each configured to receive fibrous printing material. Specifically, the first extruder 102a is configured to receive a first filament 104a from a first feed reel 106a and to provide a molten flow 108a of the first printing material, and the second extruder 102b is configured to receive a second filament 104b from a second feed reel 106b and to provide a molten flow 108b of the second printing material.

[0024] Both melting flows initially deposit on the printing bed (not shown in Figure 1) and promote the layer-by-layer growth of the supported part 120. The first printing material (build material) supplied by the first extruder 102a may be a polymer used to manufacture part 110, and the second printing material (removable support material) supplied by the second extruder 102b may be a soluble or biodegradable polymer that is a sacrificial material used to manufacture the removable support 112 under the overhang 114. The overhang 114 is not in direct contact with the lower printing layer formed from the printing bed or build material. In the part arrangement shown in Figure 1, the removable support 112 is interposed between the overhang 114 and the printing bed, but it should be understood that in alternatively configured parts, the removable support 114 may be interposed between two or more parts of part 110. Figure 2 shows, for example, an exemplary component 200, in which a removable support 202 is interposed between a defined overhang between the component 200 and the printing bed 204, and a removable support 206 is interposed between two parts of the component 200.

[0025] Referring again to Figure 1, once printing of the printed component 110 and the removable support 112 is complete, the supported component 120 may be subjected to support removal conditions 125 (e.g., dissolution or disintegration conditions) that result in the removal of the removable support 112, leaving the printed component 110 with the protrusion 114 unsupported. Support removal conditions 125 may include, for example, contacting the supported component 120 with a solvent or other liquid medium on which the removable support 112 is soluble or decomposable, and the printed component 110 is not. The removable support 112 may contain a different thermoplastic polymer than the printed component 110 to support selective dissolution or decomposition.

[0026] If the printed component is formed without protrusions or similar features, there is no need to utilize removable support material during the manufacturing of the printed component. Similarly, two or more different build materials may be used, for example, when one or more build materials are inherently structural and one or more build materials are inherently functional. In non-limiting examples, a structural polymer may be printed simultaneously with a bio-based additive mixed with it, in accordance with this disclosure.

[0027] The polymer filaments of this disclosure, suitable for the manufacture of fused filaments, may comprise a thermoplastic polymer and a bio-based additive mixed with the thermoplastic polymer in an amount effective in reducing total volatile organic compound (TVOC) emissions under additive manufacturing conditions, such as during fused filament manufacture. It should be understood that the concepts disclosed herein may also be applicable to additive manufacturing processes using particle compaction. The reduced TVOC emissions can be measured compared to the thermoplastic polymer alone, and the TVOC reduction is at least about 10% on a weight basis. TVOC measurements and their reductions can be measured by gas chromatography and / or mass spectrometry under heating conditions that simulate additive manufacturing conditions. In particular, TVOC measurements can be obtained by heating a sample from 230°C to 260°C at a heating rate of 3°C / min and collecting and analyzing the volatile substances emitted over this temperature range. The obtained data can be reported as total TVOC in μg units per gram of sample.

[0028] Polymer filaments suitable for additive manufacturing may range in diameter from approximately 0.5 mm to approximately 10 mm, approximately 1 mm to approximately 5 mm, and particularly from approximately 1.5 mm to approximately 3.5 mm. The standard filament diameter for many 3D printers using fused filament manufacturing techniques is 1.75 mm or 2.85 mm (approximately 3.0 mm). While several general ranges are provided, the polymer filament diameter may be dimensional according to the drive system for the selected printer system without departing from the scope of this disclosure. Similarly, the length and / or color of the polymer filament is not considered particularly limited in the processes disclosed herein. Preferably, the polymer filaments disclosed herein are continuous and spoolable in length, for example, at least about 0.3 m, or at least about 2 m, or at least about 3 m, or at least about 4 m, or at least about 10 m, or at least about 30 m, or at least about 60 m, or at least about 100 m, or at least about 200 m.

[0029] Other properties that can determine whether a polymer filament is suitable for additive manufacturing, particularly for fused filament manufacturing, include the temperature required for filament extrusion, which should not be unnecessarily high. A suitable filament for fused filament manufacturing can minimize printing problems such as seepage from the printing nozzle or clogging of the printing nozzle. Materials suitable for inclusion in the polymer filaments disclosed herein can form parts that separate easily from the print bed, have sufficient mechanical strength once printed, and exhibit good interlayer adhesion. Additional properties of suitable polymer filaments are specified below.

[0030] The thermoplastic polymers suitable for inclusion in the polymer filaments disclosed herein are not considered particularly limited, provided that the bio-based additives can be miscible with them through a suitable mixing process such as melt-mixing in an amount effective in reducing TVOC under additive manufacturing conditions. Some examples of suitable thermoplastic polymers may exhibit softening temperatures or melting points sufficient to facilitate deposition at temperatures in the range of about 50°C to about 400°C, or about 70°C to about 275°C, or about 100°C to about 200°C, or about 175°C to about 250°C. The melting point may be determined using ASTM E794-06(2018) with heating and cooling rates of 10°C, and the softening temperature may be determined using ASTM D6090-17.

[0031] Exemplary examples of suitable thermoplastic polymers include those commonly used in melt filament manufacturing, such as polyamides, polycaprolactones, polylactic acid, poly(styrene-isoprene-styrene) (SIS), poly(styrene-ethylene-butylene-styrene) (SEBS), poly(styrene-butylene-styrene) (SBS), and high-impact polystyrene. Examples include polystyrene (HIPS), polystyrene, thermoplastic polyurethane, poly(acrylonitrile-butadiene-styrene, ABS), polymethyl methacrylate, poly(vinylpyrrolidine-vinyl acetate), polyester, polycarbonate, polyethersulfone, polyoxymethylene, polyetheretherketone, polyetherimide, polyethylene, polyethylene oxide, polyphenylene sulfide, polypropylene, polystyrene, polyvinyl chloride, poly(tetrafluoroethylene), poly(vinylidene fluoride), poly(vinylidene fluoride-hexafluoropropylene), polyvinylpyrrolidone-co-polyvinyl acetate (PVP-co-PVA), any copolymers thereof, and any combination thereof. In some examples, the thermoplastic polymer may be a styrene polymer such as poly(acrylonitrile-butadiene-styrene). In other specific examples, the thermoplastic polymer is not polylactic acid.

[0032] Suitable bio-additives for incorporation into polymer filaments disclosed herein may include, but are not limited to, cellulose, hemicellulose, lignin, and proteins, and may include bio-derived materials having carbonaceous compounds of various compositions and concentrations. After procurement, suitable bio-additives may undergo one or more pretreatment operations by physical or chemical means before being mixed with thermoplastic polymers, such as disinfection and / or sterilization, clarification, grinding, sieving, sorting, pressing to remove excess oil, washing, solvent extraction to remove organic matter, and drying.

[0033] Pretreatment of bio-based additives may include removing water from them by any preferred method to remove excess fluid and moisture, including dehydration by air drying, vacuum drying, and / or freeze-drying. Preferred bio-based additives may optionally contain a moisture content of about 0.1% by weight or less, about 0.5% by weight or less, or about 1% by weight or less after pretreatment.

[0034] Pretreatment of bio-based additives may additionally or alternatively include reducing the particle size of the bio-based additive by any preferred method such as cutting, grinding, cryogenic grinding, milling, crushing, pulverization, sonication, homogenization, and similar particle size reduction techniques. Particle size reduction may help enhance the dispersion of the bio-based additive in the thermoplastic polymer during melt mixing. Bio-based additives suitable for use in this disclosure may have an average particle size in the range of micrometers or nanometers. In specific examples, suitable bio-based additives have an average particle size (D) of about 16 μm or less, or about 14 μm or less, or about 10 μm or less. 50 ) may have. Some examples of bio-based additives have an average particle size (D) in the range of approximately 0.1 μm to approximately 20 μm, approximately 0.4 μm to approximately 14 μm, or approximately 0.4 μm to approximately 10 μm. 50) may have. Such average particle size measurements can be performed by analysis of optical images, including SEM analysis, or using the onboard software for the Multisizer 3 by Beckman Coulter. Several particle sizes and ranges are provided, but particle sizes may be larger or smaller depending on application-specific needs, such as the supply requirements to the selected additive manufacturing platform and the properties of the thermoplastic polymer.

[0035] Suitable bio-additives for use in the disclosure herein may include grains, processed grains, grain waste, and grain by-products. Examples include, but are not limited to, distiller products, brewer's spent grains, corn gluten, sorghum germ cake and meal, peanut husks, and wheat bran. Suitable grains, grain wastes, etc., may be derived from one or more of the following: barley, corn, oats, rice, sorghum, wheat, or any mixture thereof. Some of the polymer filaments of this disclosure may include brewer's spent grains, which may be derived from the beer brewing process. Additional bio-additives suitable for use in the disclosure herein may include coffee beans and coffee grounds (including spent coffee grounds). These bio-additives may be used alone or in combination with grains, grain wastes, etc., in the polymer filaments disclosed herein.

[0036] Other bio-based additives include plant protein products such as canola meal, cottonseed cake and meal, safflower meal, soybean (including organic and genetically modified soybeans) feed and meal, as well as alfalfa, bird's foot trefoil, cruciferous plants (e.g., chau molière), kale, rapeseed (canola), rutabaga, and turnips, and grasses (e.g., black locust, fescue, Bermuda grass, broom, heathergrass, meadowgrass, orchard grass). Examples include fibrous materials such as plant materials (grass, ryegrass, and timothy grass), millet, and soybeans; outer layers and fibrous substances such as grass, rice husks, cotton, jute, hemp, flax, bamboo, sisal, abaca, straw, corn cobs, rice husks, coconut hair, algae, seaweed, water hyacinth, cassava, bagasse, almond shells, crushed husks, buckwheat hulls, legumes, and synthetic cellulose; and processed and recycled paper products, wood, wood-related materials, particleboard, etc.

[0037] The filling of polymer filaments with bio-based additives disclosed herein can be adjusted to achieve a desired degree of TVOC reduction. In exemplary examples, the bio-based additive may be present in an effective amount to achieve at least about 10% TVOC reduction, or about 25% TVOC reduction, or at least about 40% TVOC reduction, or at least about 60% TVOC reduction, or at least about 80% TVOC reduction. The reduction rate is given by the formula |TVOC|. poly -TVOC fil │ / TVOC poly This can be determined by, in the formula, TVOC poly This is the TVOC of the polymer alone, and TVOC filThis refers to the TVOC of a polymer filament containing a bio-based additive. In some examples, the bio-based additive may be present in the polymer filament (or polymer melt used to form the polymer filament) of this disclosure in amounts of about 0.5% by weight or more, or about 1% by weight or more, or about 2% by weight or more, or about 5% by weight or more, or about 10% by weight or more. In more specific examples, the bio-based additive may be present in the polymer filament (or polymer melt used to form the polymer filament) in amounts ranging from about 0.5% by weight to about 10% by weight, or about 0.5% by weight to about 7.5% by weight, or about 1% by weight to about 5% by weight, or about 1% by weight to about 4% by weight. While several ranges are provided as examples, the filling of the bio-based additive may be selected so that the polymer filament remains printable by melt filament manufacturing while maintaining structural integrity as a continuous filament and still reducing TVOC emissions during additive manufacturing, as specified herein.

[0038] The polymer filaments of this disclosure may be formed by a melt-mixing process. A preferred melt-mixing process involves melt-mixing a thermoplastic polymer with a bio-based additive, followed by extrusion of the resulting melt mixture. Alternatively, melt-mixing may be carried out directly via extrusion in an extruder. During filament extrusion, the thermoplastic polymer may be melt-mixed with one or more bio-based additives and additional optional additives in an extruder, such as a uniscrew or multiscrew extruder, and mechanically passed through a die. The melt polymer mixture may be dimensioned according to one or more openings in the die to form a continuous polymer filament. Once the polymer filament has cooled, it may be collected and spooled into a form suitable for end-use applications, such as supplying printing devices for molten filament production. In addition, the melt-mixed polymer composition may also be converted into other forms, including pelletized forms, depending on the application, without departing from this disclosure.

[0039] Accordingly, the method for forming a polymer filament according to the present disclosure comprises forming a molten mixture containing a thermoplastic polymer and a bio-based additive, and extruding and cooling the molten mixture to form a polymer filament containing a bio-based additive mixed with the thermoplastic polymer, wherein the bio-based additive is present in an amount effective in reducing TVOC emissions by at least about 10% on a weight basis, as determined by gas chromatography and measured relative to the thermoplastic polymer alone, under additive manufacturing conditions.

[0040] The additive manufacturing process carried out by the molten filament manufacturing according to this disclosure may include providing a polymer filament as described herein, heating the polymer filament to a temperature above its melting point or softening temperature to form a softened polymer material, and depositing the softened polymer material layer by layer to form a printed part. The polymer filament may be deposited layer by layer on its own, or in combination with a suitable removable support material (sacrificial material) also deposited from a continuous filament to form a printed part. Suitable types of parts are not considered to be particularly limited in this disclosure.

[0041] In some molten filament manufacturing methods, the print head may include one or more extruders such that a first polymer filament containing build material is deposited from a first extruder. The build material may include the polymer filament as disclosed above. Optionally, a second polymer filament containing a removable support material (sacrificial material) may be deposited from a second extruder to form a removable support for defining one or more protrusions in a printed part formed from the build material. The second build material may also be deposited alternately with the polymer filaments disclosed herein.

[0042] While polymer filaments may be particularly advantageous when formed according to the disclosure herein, polymer compositions containing bio-based additives should be understood as being able to be formed into pellets or other forms containing particles after melt-mixing. For example, a thermoplastic polymer and one or more bio-based additives may be melt-mixed, then extruded into large fibers, and then cut, shredded, or pulverized to obtain polymer pellets or polymer powders containing the polymer and the bio-based additives mixed together. The form of polymer pellets or polymer powders may be similar to the form of polymer filaments suitable for additive manufacturing. Similar to polymer filaments, polymer pellets or polymer powders can then be processed into printed parts under suitable additive manufacturing conditions.

[0043] In addition to additive manufacturing, polymer pellets (or other polymer compositions) incorporating thermoplastic polymers and bio-based additives mixed therein in amounts effective in reducing TVOC emissions may be applicable to other manufacturing techniques such as extrusion, co-extrusion, extrusion coating, injection molding, injection blow molding, injection stretch blow molding, thermoforming, cast film extrusion, blow film extrusion, foaming, extrusion blow molding, injection stretch blow molding, rotational molding, pultrusion, calendering, and lamination.

[0044] Embodiments disclosed herein include the following:

[0045] A. Polymer filaments compatible with molten filament manufacturing. The polymer filament comprises a thermoplastic polymer and a bio-based additive mixed with the thermoplastic polymer in an amount effective in reducing total volatile organic compound (TVOC) emissions by at least about 10% by weight under additive manufacturing conditions, as determined by gas chromatography and measured relative to the thermoplastic polymer alone.

[0046] B. A method for forming a polymer filament suitable for molten filament manufacturing. The method comprises forming a molten mixture containing a thermoplastic polymer and a bio-based additive, and extruding and cooling the molten mixture to form a polymer filament containing a thermoplastic polymer and a bio-based additive mixed with it, wherein the bio-based additive is present in an amount effective in reducing total volatile organic compound (TVOC) emissions by at least about 10% on a weight basis under additive manufacturing conditions, as determined by gas chromatography and measured relative to the thermoplastic polymer alone.

[0047] C. Additive manufacturing process. The additive manufacturing process includes providing a polymer filament comprising a thermoplastic polymer and a bio-based additive mixed with the thermoplastic polymer in an amount effective in reducing total volatile organic compound (TVOC) emissions by at least about 10% on a weight basis under additive manufacturing conditions, as determined by gas chromatography and measured relative to the thermoplastic polymer alone; heating the polymer filament to a temperature above the softening temperature of the thermoplastic polymer to form a softened polymer material; and depositing the softened polymer material layer by layer to form a printed part.

[0048] Each of embodiments A, B, and C may have one or more of the following additional elements in any combination.

[0049] Element 1: The bio-based additive is present in an amount effective enough to reduce TVOC emissions by at least approximately 25% on a weight basis.

[0050] Element 2: A bio-based additive is mixed with the thermoplastic polymer in an amount of approximately 1% by weight or more based on the total mass.

[0051] Element 3: Bio-based additives are freeze-dried.

[0052] Element 4: The bio-based additive contains approximately 1% or less water by weight.

[0053] Element 5: The bio-based additive has an average particle size of approximately 14 μm or less.

[0054] Element 6: The bio-based additive has an average particle size of approximately 0.4 μm to approximately 14 μm.

[0055] Element 7: The bio-based additive includes coffee grounds, grain waste, or any combination thereof.

[0056] Element 8: Bio-based additives include brewer's used grain.

[0057] Element 9: The thermoplastic polymer includes polymers selected from the group consisting of polyamides, polycaprolactones, poly(styrene-isoprene-styrene) (SIS), poly(styrene-ethylene-butylene-styrene) (SEBS), poly(styrene-butylene-styrene) (SBS), high-impact polystyrene, polystyrene, thermoplastic polyurethanes, poly(acrylonitrile-butadiene-styrene) (ABS), polymethyl methacrylate, poly(vinylpyrrolidine-vinyl acetate), polyesters, polycarbonates, polyethersulfones, polyoxymethylenes, polyetheretherketones, polyetherimides, polyethylenes, polyethylene oxides, polyphenylene sulfide, polypropylenes, polystyrenes, polyvinyl chlorides, poly(tetrafluoroethylenes), poly(vinylidene fluoride), poly(vinylidene fluoride-hexafluoropropylenes), any copolymers thereof, and any combination thereof.

[0058] Element 10: The thermoplastic polymer is poly(acrylonitrile-butadiene-styrene) polymer.

[0059] Element 11: The thermoplastic polymer is not polylactic acid.

[0060] As non-limiting embodiments, exemplary combinations applicable to A, B, and C include 1 and 2; 1 and 3 or 4; 1 and 5 or 6; 1 and 7 or 8; 1 and 9; 1 and 10; 1 and 11; 2 and 3 or 4; 2 and 5 or 6; 2 and 7 or 8; 2 and 9; 2 and 10; 2 and 11; 3 or 4, and 5 or 6; 3 or 4, and 7 or 8; 3 or 4, 9; 3 or 4, 10; 3 or 4, 11; 5 or 6, and 7 or 8; 5 or 6, 9; 5 or 6, 10; 5 or 6, 11; 7 or 8, and 9, 7, 8 or 10; 7 or 8, 11; 9 and 10; 9 and 11; and 10 and 11.

[0061] To facilitate a better understanding of this disclosure, the following examples of preferred or representative embodiments are given. The following examples should not be interpreted in any way as limiting or defining the scope of the invention. [Examples]

[0062] In the following examples, polymer filaments were prepared using poly(acrylonitrile-butadiene-styrene) (ABS) polymer mixed with selected bio-based additives, as further specified below. Sample polymer filaments were prepared using a Filabot EX6 filament device equipped with a single-screw extruder in a barrel heated to 185°C. The sample components were filled and mixed into the device, the filament was extruded through a 2.85 mm die, air-cooled, and wound onto a spool.

[0063] Comparative sample. A comparative polymer filament was prepared by extruding ABS alone. The filament was white.

[0064] Sample 1: Spent grains (beer brewing waste) of an ABS-brewer. Polymer filaments of Sample 1 were produced from ABS containing 4 wt% of spent grains (beer brewing waste). Before combining with ABS, the spent grains were dehydrated by freeze-drying for 3 days to reduce the water content to less than 1%. The dried ground material was then transferred to a blade mill for grinding and sieved through a 58 μm sieve. As determined by particle analysis using a Multisizer 3 (Beckman Coulter), the particles had a D 50 diameter of less than 14 μm. The resulting filaments were light brown, and spots due to the bio-based additive were observed on the surface.

[0065] Sample 2: ABS-spent coffee grounds. Polymer filaments of Sample 2 were produced from ABS containing 4 wt% of spent coffee grounds. Before combining with ABS, the spent coffee grounds were dried using a dehydrator for 24 hours to reduce the water content to less than 1%. The dried ground material was then transferred to a blade mill for grinding and sieved through a 58 μm sieve. As determined by particle analysis using a Multisizer 3 (Beckman Coulter), the particles had a D 50 diameter of less than 11 μm. The resulting filaments were light brown, and spots due to the bio-based additive were observed on the surface.

[0066] Figures 3A, 3B, and 3C show transmission electron microscopy (TEM) images of the filaments of the comparative sample, Sample 1, and Sample 2. The white portions of the TEM images indicate the porosity of the filaments. As shown, the samples containing the bio-based additive exhibited a lower degree of porosity, and Sample 2 visually exhibited the lowest porosity.

[0067] Test specimens. Dogbone test specimens for Sample 1, Sample 2, and the comparative sample were produced using an Ultimizer S5 3-D printer according to ASTM D638-14. Printing was performed at a printhead temperature of 240°C, a floor temperature of 80°C, and a line height of 0.2 mm. The tensile strength of the test specimens was measured according to ASTM D638. All samples exhibited similar mechanical properties.

[0068] TVOC measurement. Polymer filaments were analyzed under heating conditions intended to mimic suitable additive manufacturing conditions for printing ABS filaments. Under simulated additive manufacturing conditions, samples were heated from 230°C to 260°C at a heating rate of 3°C / min, and volatile matter was collected during this temperature range to determine TVOC emissions. TVOC emissions were measured using gas chromatography / mass spectrometry.

[0069] The measured TVOC emissions are summarized in Table 1 below. The difference rate and reduction rate of TVOC emissions between Sample 1 and Sample 2 were determined using the TVOC measurements of the comparison sample. The reduction rate is given by the formula: |TVOC| poly -TVOC fil │ / TVOC poly Determined by, the difference rate is given by the formula TVOC poly -TVOC fil │ / (TVOC poly +TVOC fil Determined by ) / 2, in the formula, TVOC poly This refers to the TVOC of the polymer alone, and TVOC fil This is the TVOC of polymer filaments containing bio-based additives. [Table 1]

[0070] The individual reductions in styrene relative to the comparative samples were also analyzed by GC / MS, and as shown in Table 2, a reduction rate of 38% was observed for each of samples 1 and 2 under additive manufacturing conditions. [Table 2]

[0071] All documents described herein are incorporated herein by reference for the purposes of all jurisdictions in which such practice is permitted, and include any preferred documents and / or test procedures to the extent that they do not conflict with this text. As is evident from the general description and specific embodiments set forth above, the forms of this disclosure have been illustrated and described, but various modifications can be made without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not intended to be limited thereto. For example, the compositions described herein do not have to include any components or compositions not expressly enumerated or disclosed herein. Any method may omit any steps not enumerated or disclosed herein. Similarly, the terms “comprising” are considered synonymous with the terms “including.” Whenever a method, composition, element, or group of elements is preceded by the transitional phrase “comprising,” it is understood that the inventors may also intend the same composition or group of elements by the transitional phrases “essentially consisting of,” “consisting of,” “selected from a group consisting of,” or “is,” preceding an enumeration of compositions, elements, or multiple elements, and vice versa.

[0072] Unless otherwise stated, all numbers used herein and in the related claims, representing quantities of components, properties such as molecular weight, and reaction conditions, should be understood in all cases as being modified by the term "approximately." Therefore, unless otherwise indicated, the numerical parameters described in the following specification and the appended claims are approximations that may vary depending on the desired properties to be obtained by embodiments of the present invention. At the very least, without any intention to limit the application of the doctrine of equivalents to the claims, each numerical parameter should be interpreted by applying the usual rounding method in light of the number of significant figures reported.

[0073] Whenever a numerical range with lower and upper limits is disclosed, any number and any range included within that range are specifically disclosed. In particular, all ranges of values ​​disclosed herein (in the form of "about a to about b," or equivalently "approximately a to b," or equivalently "about a to b") should be understood to describe all numbers and ranges encompassed within a broad range of values. Furthermore, terms in the claims have plain, ordinary meanings unless explicitly and clearly defined by the patent holder. In addition, when used in claims, the indefinite article "a" or "an" is defined herein to mean one or more of the elements it introduces.

[0074] One or more exemplary embodiments are presented herein. For clarity, not all features of physical implementations are described or represented in this application. It is understood that in developing physical embodiments of the disclosure, numerous implementation-specific decisions must be made to achieve the developer's objectives, which vary by implementation and from time to time, including compliance with system-related, business-related, government-related, and other constraints. While this may require considerable time and effort from the developer, such efforts would still be routine work for those skilled in the art who are interested in the disclosure.

[0075] Accordingly, this disclosure is well adapted to achieve the objectives and benefits mentioned herein, as well as those inherent thereto. The specific embodiments described above are illustrative only, and this disclosure may be modified and implemented in different but equivalent ways, which will be obvious to those skilled in the art who have a teaching interest in this specification. Furthermore, it is not intended to limit this specification to any structural or design details other than those described in the following claims. Accordingly, it is obvious that the specific exemplary embodiments disclosed above may be modified, combined or altered, and all such variations will be considered within the scope and spirit of this disclosure. The embodiments preferably illustrated herein may be implemented in the absence of any elements not specifically disclosed herein, and / or any optional elements disclosed herein.

Claims

1. 1. A polymer filament adapted for fused filament manufacturing, comprising: A thermoplastic polymer that is not polylactic acid; a bio-based additive admixed with the thermoplastic polymer in an amount effective to reduce total volatile organic compound (TVOC) emissions by at least about 10% by weight under additive manufacturing conditions as determined by gas chromatography and measured relative to the thermoplastic polymer alone; 1) the bio-based additive comprises coffee grounds, grain waste, or any combination thereof, and the thermoplastic polymer is a poly(acrylonitrile-butadiene-styrene) polymer; or 2) the bio-based additive comprises brewer's spent grain; The bio-based additive is blended with the thermoplastic polymer at about 0.05% to about 10% by weight based on the total weight of the polymer; and The polymer filament has a diameter ranging from about 1.5 mm to about 3.5 mm.

2. 10. The polymer filament of claim 1, wherein the bio-based additive comprises about 1% by weight or less of water.

3. 10. The polymer filament of claim 1, wherein the bio-based additive has an average particle size of about 14 μm or less.

4. 1. A method for forming a polymer filament compatible with fused filament manufacturing, comprising: forming a molten mixture comprising a thermoplastic polymer that is not polylactic acid and a bio-based additive; and extruding and cooling the molten mixture to form a polymer filament comprising the bio-based additive admixed with the thermoplastic polymer; 1) the bio-based additive comprises coffee grounds, grain waste, or any combination thereof, and the thermoplastic polymer is a poly(acrylonitrile butadiene styrene) polymer; or 2) the bio-based additive comprises brewer's spent grain; the polymer filament has a diameter ranging from about 1.5 mm to about 3.5 mm; the bio-based additive is present in an amount effective to reduce total volatile organic compound (TVOC) emissions by at least about 10% by mass under additive manufacturing conditions as determined by gas chromatography and measured relative to the thermoplastic polymer alone; and The method, wherein the bio-based additive is admixed with the thermoplastic polymer at about 0.05% to about 10% by weight based on the total weight.

5. 5. The method of claim 4, wherein the bio-based additive comprises about 1% water or less by weight.

6. 5. The method of claim 4, wherein the bio-based additive has an average particle size of about 14 μm or less.

7. 1. An additive manufacturing process comprising: providing a polymer filament comprising a thermoplastic polymer and a bio-based additive admixed with the thermoplastic polymer in an amount effective to reduce total volatile organic compound (TVOC) emissions by at least about 10% by mass under additive manufacturing conditions as determined by gas chromatography and measured relative to the thermoplastic polymer alone; heating the polymer filaments above a softening temperature of the thermoplastic polymer to form a softened polymer material; and depositing the softened polymeric material layer by layer to form a printed part; The thermoplastic polymer is not polylactic acid, the bio-based additive is blended with the thermoplastic polymer at about 0.05% to about 10% by weight based on the total weight of the polymer; 1) the bio-based additive comprises coffee grounds, grain waste, or any combination thereof, and the thermoplastic polymer is a poly(acrylonitrile-butadiene-styrene) polymer; or 2) the bio-based additive comprises brewer's spent grain; and The process wherein the polymer filaments have a diameter ranging from about 1.5 mm to about 3.5 mm.

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