Coated Filament for Improved Additively Manufactured Parts

Abstract

To provide a coated filament that prevents formation of voids between adjacent beads in filament based additive manufacturing such as fused filament fabrication.SOLUTION: A coated filament 10 for use in additive manufacturing includes a base polymer layer 8 formed of a base polymer material 2, and a coating polymer layer 9 formed of a coating polymer material 7. At least the coating material 7 is susceptible to dielectric heating in response to electromagnetic radiation, thereby promoting fusion between adjacent beads of the coated filament that are deposited during the additive manufacturing process. Specifically, when electromagnetic radiation is applied to an interface area between two adjacent beads of the coated filament, the polymer coating layer 9 melts to diffuse across the interface area, thereby preventing formation of voids.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an apparatus and method for additive manufacturing, and more particularly to additive manufacturing techniques that use filaments as an additive material. The additive manufacturing processes disclosed herein are useful in manufacturing parts, such as environmental control ducts, door panels, tools, jigs, fixtures, and the like. Additionally, embodiments of the present disclosure may be used in a wide variety of applications, particularly in the aerospace, marine, automotive, and other transportation industries, such as casings for auxiliary power units (APUs). [Background technology]

[0002] Parts and other articles are produced using a variety of manufacturing techniques, depending on the part's performance requirements and the availability of manufacturing equipment. One additive manufacturing method that can be used to build objects is fused filament fabrication (FFF). In this method, a filament is heated into a bead that is deposited onto a substrate in successive buildable layers to form an article. The filament is typically made of thermoplastic, polycarbonate, or other materials of similar composition. Filament-based additive manufacturing such as FFF can result in voids between adjacent beads, reducing interlayer strength and resulting in a weaker structural article. Summary of the Invention

[0003] According to one aspect of the present disclosure, there is provided a coated filament for use in an additive manufacturing process, the coated filament including a base polymer layer formed of a base polymer material having a first dielectric loss factor and a coated polymer layer overlying the base polymer layer and formed of a coating polymer material having a second dielectric loss factor, the second dielectric loss factor of the coating polymer material being greater than the first dielectric loss factor of the base polymer material.

[0004] According to another aspect of the present disclosure, there is provided a method of making a coated filament for use in an additive manufacturing process, comprising advancing a polymer filament along a path, the polymer filament formed from a base polymer material, applying a liquid paint to an exterior surface of the polymer filament at a location on the path, the liquid paint formed from a coating polymer material, and drying the liquid paint on the polymer filament to form the coated filament, the coated filament including a base polymer layer formed by the polymer filament and a coated polymer layer formed by the liquid paint after drying.

[0005] According to a further aspect of the present disclosure, there is provided a method of manufacturing an article by fused filament manufacturing, comprising forming a coated filament by advancing a polymer filament along a path, the polymer filament being formed of a base polymer material, applying a liquid paint to an exterior surface of the polymer filament at a location on the path, the liquid paint being formed of a coating polymer material, and drying the liquid paint on the polymer filament to form the coated filament, the coated filament including a base polymer layer formed by the polymer filament and a coating polymer layer formed by the liquid paint after drying. The method further comprises depositing adjacent first and second beads of the coated filament on a substrate, and dielectrically heating at least the coating polymer layer in each of the first and second beads using electromagnetic radiation, thereby fusing the first and second beads of the coated filament at an interface region.

[0006] The described features, functions, and advantages may be realized individually in various embodiments, or may be combined with each other in other embodiments, further details of which will become apparent by reference to the following description and drawings. [Brief description of the drawings]

[0007] The novel features believed characteristic of the illustrative embodiments are set forth in the appended claims. However, the illustrative embodiments and preferred modes of use, as well as their objects and advantages, will best be understood by reference to the following detailed description of illustrative embodiments of the present disclosure taken in conjunction with the accompanying drawings.

[0008] [Figure 1] FIG. 1 illustrates the coating of a polymer filament with a polymer coating. [Diagram 2] FIG. 1 illustrates an article manufactured by conventional FFF technology. [Diagram 3] FIG. 2 illustrates a coated filament formed by a method for manufacturing a coated filament. [Figure 4] FIG. 4 is an end view of the coated filament of FIG. [Diagram 5] FIG. 1 is a schematic diagram of an exemplary system for manufacturing an article by fused filament manufacturing according to the present disclosure. [Figure 6] FIG. 6 illustrates two deposition beads of a coated filament deposited by the system of FIG. [Figure 7] FIG. 7 illustrates two deposition beads of the coated filament shown in FIG. 6 after the interface region has been exposed to electromagnetic radiation. [Figure 8] FIG. 1 illustrates an article formed by multiple layers of deposited beads. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The following detailed description relates to fused filament fabrication techniques that use electromagnetically sensitive polymer coatings for reinforcement. In some embodiments, for example, various portions of an article are reinforced using electromagnetic radiation. In some examples, portions of an article that require increased strength are identified and exposed to electromagnetic radiation for a given amount or duration.

[0010] Reference is made to the accompanying drawings which form a part hereof, and in which specific examples or embodiments are shown by way of illustration. Like numerals in the several drawings refer to like elements. <Definition>

[0011] "Fused Filament Fabrication" (FFF) is an additive manufacturing technique used to build up successive layers of material to form an article, such as a three-dimensional product, prototype, or model. The process is a rapid prototyping and manufacturing process in which successive layers of molten material are built up to rapidly create models, articles, or the like.

[0012] As used herein, "filament" refers to a thin, thread-like feed material used in additive manufacturing processes. Description of the embodiment

[0013] Turning now to the figures, FIG. 1 illustrates a process of converting a polymer filament 2 into a coated filament 10 that can be used in an additive manufacturing process to create an article with higher structural integrity. Specifically, the polymer filament 2 is unwound from a first spool 4 and pulled through a reservoir 6 that holds a liquid paint 7. Thus, upon exiting the reservoir 6, the polymer filament 2 is coated with the liquid paint 7. The liquid paint 7 then dries, leaving the coated filament 10 with a base polymer layer 8 (formed by the polymer filament 2) and a coating polymer layer 9 overlying the base polymer layer 8. The coated filament 10 is then collected and wound onto a second spool 12 for use in an additive manufacturing process. In this example, the rotation of the first spool 4 and the second spool 12 are controlled such that the rate at which the polymer filament 2 is unwound from the first spool 4 is substantially the same as the rate at which the coated filament 10 is wound onto the second spool 12.

[0014] The materials used to form the base polymer layer 8 and the coat polymer layer 9 in the coated filament 10 can be selectively heated during a filament-based additive manufacturing process to promote interfilament chain diffusion and bonding, resulting in a shaped article with improved structural integrity. As described in more detail below, the materials used for the base polymer layer 8 and the coat polymer layer 9 can be selected based on their relative reactivity to dielectric heating, as well as the closeness of their melting points and solubility parameters.

[0015] With regard to responsiveness to dielectric heating, for example, the material used for the coated filament 10 is selected such that the coating polymer layer 9 is more susceptible to heating in response to electromagnetic radiation than the base polymer layer 8. The ability of a material to dissipate irradiated electromagnetic energy in the form of heat is quantified by a property known as the dielectric loss factor (also known as the loss factor and represented by the symbol tan δ). A material with a higher dielectric loss factor will heat up more in response to an applied electromagnetic field than a material with a lower dielectric loss factor. To concentrate the heating on the outer surface of the coated filament 10, the coating polymer layer 9 is formed of a coating polymer material with a higher dielectric loss factor than the base polymer material used for the base polymer layer 8. In some examples, the coating polymer material has a tan δ value that is at least about 50 times the tan δ value of the base polymer material. Additionally or alternatively, the base polymer material may have a tan δ value less than 0.05 and the coating polymer material may have a tan δ value greater than 0.05.

[0016] The coated filament 10 may also use materials with similar melting points for the base polymer layer 8 and the coating polymer layer 9, which may improve the strength of the built article formed with the coated filament layers deposited during the additive manufacturing process. As described above, the coating polymer material has a higher dielectric loss factor and therefore generates heat in direct response to the application of electromagnetic energy. The base polymer material may be selected to have a melting point close to that of the coating polymer material, such that heating the coating polymer layer 9 with electromagnetic energy may also heat at least the outer portion of the base polymer layer 8. This indirect heating of the base polymer layer 8 may keep the base polymer layer 8 in a softened and / or molten state for a longer period of time, which may further promote diffusion and bonding between adjacent beads of the coated filament 10 after deposition on the substrate. The respective melting points of the base polymer material and the coating polymer material allow for the formation of solid and liquid morphologies. In some examples, the base polymer material has a first melting point and the coating polymer material has a second melting point, the first melting point of the base polymer material being within 20 degrees Celsius of the second melting point of the coating polymer material. It has been found that such materials having melting points within about 20 degrees Celsius, or about 18 degrees Celsius, or about 15 degrees Celsius, can generate sufficient heat to prolong the molten state of the base polymer layer 8 to promote diffusion and bonding between adjacent beads of the coated filament 10 that are deposited and heated during additive manufacturing.

[0017] The materials selected for the base polymer layer 8 and the coat polymer layer 8 may also have compatible solubility parameters to further promote bonding between adjacent beads and build layers of the coated filament 10 when used in an additive manufacturing process. For example, the coat polymer material may be immiscible with the base polymer material to prevent phase separation and promote fusion of the base polymer layer between adjacent beads of the deposited coated filament 10 during additive manufacturing. In some examples, the base polymer material has a first solubility parameter and the coat polymer material has a second solubility parameter that differs from the first solubility parameter by about 10 J / cc. 0.5 The difference in solubility parameters is about 10 J / cc. 0.5 , or about 8 J / cc 0.5 , or about 5J / cc 0.5 Materials within the above range have been found to be advantageous in promoting mixing when heated during additive manufacturing processes.

[0018] With the above in mind, suitable base polymer materials include polyethylene, polyethylene terephthalate, polypropylene, polyamide, polyetheretherketone, polyphenylene sulfide, polyetherimide, polystyrene, acrylonitrile-butadiene-styrene, polyacrylate, polyacrylonitrile, polycarbonate, or any mixture thereof.

[0019] Suitable coating polymeric materials include polyvinyl alcohol, polyvinylidene fluoride, polyurethane, polyamideimide, polyamide, polyvinyl chloride, acrylic, cellulose ester, or mixtures thereof. Other examples of suitable coating polymeric materials include high dielectric loss factor materials and solvents containing -OH, -NH, C=O, -N=O functional groups. Further examples of suitable coating polymeric materials include polyacrylonitrile (tan δ=0.1 at 60 Hz), polyethylene glycol, or mixtures thereof. In some examples, the coating polymeric material is particularly responsive to electromagnetic energy in a particular frequency range, such as microwave energy in the gigahertz range.

[0020] Table 1 compares the dielectric loss factor, melting point, and solubility parameters for examples in which the coating polymer material is polyvinyl alcohol and the base polymer material is Ultem® 1010 (a polyetherimide). [Table 1]

[0021] In this example, using Ultem® 1010 (a polyetherimide) as the base polymer material and polyvinyl alcohol as the coating polymer material is advantageous because polyvinyl alcohol has a high dielectric loss factor (tan δ=0.185 in the MHz-GHz frequency range) compared to Ultem® 1010 (tan δ=0.001 in the MHz-GHz frequency range), the melting points of these two materials differ by 14 degrees Celsius, and their solubility parameters are close to each other, i.e., compatible.

[0022] In addition to the chemical properties, the base polymer layer 8 and the coating polymer layer 9 may further have suitable physical properties to promote fusion, bonding, and mixing. For example, the base polymer layer 8 may have a thickness in the range of about 0.1 to about 5 millimeters, or about 0.5 to about 4 millimeters, or about 1 to about 3 millimeters. The coating polymer layer 9 may have a thickness in the range of about 1 micron to about 1,000 microns, or about 50 microns to about 750 microns, or about 100 microns to about 300 microns. Furthermore, the liquid coating 7 may be characterized by a viscosity of about 0.1 to about 10 Pascal seconds (Pa·s), or about 0.5 to about 8 Pa·s, or about 1 to about 5 Pa·s.

[0023] 2 shows an article formed by a conventional FFF process. One embodiment of FFF is an additive manufacturing technique in which a filament on a spool is fed into an extruder (the following components used in the FFF process and in producing object 20 are not shown). The extruder uses a torque and pinch system to feed and pull the filament back in precise increments relative to a heater block. The heater block melts the filament to a molten state, where the heated filament is reduced in diameter and extruded out of a nozzle where it is deposited onto a substrate or work plate. In a typical FFF process, multiple build layers are built up one on top of the other to form a three-dimensional article.

[0024] Specifically, and referring to FIG. 2, the article 20 is produced by successively depositing adjacent beads of uncoated filament 22 until the article 20 is completed. For example, the article 20 of FIG. 2 is formed by three build layers, each of which includes four beads of uncoated filament 22. The beads of uncoated filament 22 deposited on the substrate 54 in this example have seams between adjacent beads. Due to the nature of conventional uncoated polymer filaments, once the first bead is deposited, it cools and is no longer in a fully molten state when the next adjacent bead of uncoated filament is deposited. Due to the at least partial solidification of the previously deposited bead, voids 24 form between adjacent beads of uncoated filament 22 within a given build layer and between adjacent build layers, thereby weakening the article 20.

[0025] As best seen in Figures 3 and 4, a coated filament 10 according to the present disclosure includes both a base polymer layer 8 and a coating polymer layer 9. As discussed above, the materials of each of the base polymer layer 8 and the coating polymer layer 9 are selected to promote diffusion and bonding between adjacent beads and layers of the build, thereby eliminating voids 24. In one example, the coated filament 10 is manufactured using the process outlined in Figure 1, although the subject matter of the present disclosure is not limited to any particular manufacturing method. In some examples, the coated filament 10 is a filament used in an additive manufacturing machine, such as a machine using FFF or other commonly used additive manufacturing techniques.

[0026] 5 shows an example of a system 100 for manufacturing an article using a coated filament 10 by FFF and exposure to electromagnetic radiation as described below. The coated filament 10 having a base polymer layer 8 and a coating polymer layer 9 is fed to a nozzle 52. The nozzle 52 heats the coated filament 10 to a molten state before it is extruded from the nozzle 52 and deposited as a first bead 56 on a substrate 54. The substrate 54, in one non-limiting example, is a work table. The substrate 54 may be heated to prevent the filament from solidifying and adhering to the substrate 54.

[0027] The nozzle 52 heats the coated filament 10 to a molten state at a temperature of about 100 to about 500 degrees Celsius, or about 200 to about 350 degrees Celsius, or about 230 to about 285 degrees Celsius. The coated filament 10 is then deposited onto the substrate 54 at a rate of about 20 to about 200 mm / sec, or about 35 to about 150 mm / sec, or about 50 to about 100 mm / sec.

[0028] After the first bead 56 is deposited, subsequent beads are formed on the substrate 54, as best seen in FIG. 6. The number of beads per build layer and the number of build layers will depend on the particular article being manufactured and the additive manufacturing technique selected. Regardless of the technique employed, the coated filament 10 can be used to enhance the bond between adjacent beads and build layers. For example, FIG. 6 shows a front cross-sectional view of adjacent deposited beads 60, including a first bead 56 and a second bead 57 of the coated filament 10. Each bead in the deposited bead pair 60 is formed by the coated filament 10 extruded from the nozzle 52 and deposited on the substrate 54, and includes a base polymer layer 8 and a coating polymer layer 9. To enhance the bond between the first bead 56 and the second bead 57, an interface region 62 between the beads 56, 57 is irradiated with electromagnetic radiation 64. In one non-limiting example, the interface region 62 is the region located between the first bead 56 and the second bead 57, while in another example, the interface region 62 is the region between two build layers. In a further non-limiting embodiment, the electromagnetic radiation 64 is applied to the entire article (such as article 80 shown in FIG. 8) and not just the region between adjacent beads. In this case, because the base polymer material has a lower dielectric loss factor than the coating polymer material, only the coating polymer layer 9 of each bead is heated by the electromagnetic radiation, and not the base polymer layer 8.

[0029] In one non-limiting example, the electromagnetic radiation 64 is applied from a heating source 65. In this example, the heating source 65 directs the electromagnetic radiation to the interface region 62 of the article or the entire article to strengthen a localized region of the article or the entire article, and controls the duration for which the electromagnetic radiation 64 is applied. For example, applying the electromagnetic radiation 64 to the interface region 62 can further heat and melt the base polymer layer 8 of the adjacent bead. In one example, the electromagnetic radiation 64 can be microwaves having a frequency in the range between 300 MHz and 300 GHz. In this case, the coated polymer material has a high dielectric loss factor and is susceptible to microwave radiation, i.e., dielectric heating. In a further non-limiting example, the electromagnetic radiation 64 is applied continuously while the coated filament 10 is being deposited. In another example, the electromagnetic radiation 64 is applied selectively between adjacent deposited beads.

[0030] Since the coating polymer material has a higher dielectric loss factor and the base polymer material has a lower dielectric loss factor, the frequency of the electromagnetic radiation can be selected such that only the coating polymer layer 9 directly melts in response to the electromagnetic radiation. Alternatively, the base polymer material may have a melting point close to that of the coating polymer material, in which case the base polymer layer 8 at least partially melts in response to heating of the coating polymer layer 9. Thus, in response to the electromagnetic radiation 64, the coating polymer layer 9 melts directly and the base polymer layer 8 melts indirectly. In another example, the electromagnetic radiation 64 may directly heat both the coating polymer layer 9 and the base polymer layer 8. In either case, the melted portions of the base polymer layer 8 of adjacent beads fuse together, thereby preventing the formation of voids between adjacent beads and improving the structural integrity of the shaped article.

[0031] If the coat polymer material and the base polymer material have compatible solubility parameters (see non-limiting examples in Table 1), then melting both the coat polymer layer 9 and the base polymer layer 8 will form a homogenous mixture, and therefore no phase separation will occur when the molten layers subsequently cool and solidify.

[0032] 7 illustrates a first bead 56 and a second bead 57 of the coated filament 10 fused together to form a fused bead pair 70 after being melted by electromagnetic radiation 64. In this illustration, the electromagnetic radiation 64 has heated the coating polymer layer 9 of the first bead 56 and the second bead 57, which in turn melts at least a portion of the base polymer layer 8.

[0033] FIG. 8 illustrates an article 80 formed using the coated filament 10 in an additive manufacturing technique. In this example, the article 80 is produced by disposing beads 72 of the coated filament 10 on a substrate 54. Specifically, FIG. 8 illustrates three build layers 74, each including four beads 72. Also, in this example, electromagnetic radiation 64 is applied to fuse the base polymer layer 8 and the coat polymer layer 9 of adjacent beads of the coated filament 10. The resulting article 80 does not have any voids between the beads 72 or the build layers 74. <Additional Notes>

[0034] The present disclosure also includes embodiments or examples according to the following appendices.

[0035] Appendix 1. A coated filament (10) for use in an additive manufacturing process, comprising: a base polymer layer (8) formed of a base polymer material having a first dielectric loss factor; a coated polymer layer (9) covering the base polymer layer (8) and formed by a coated polymer material having a second dielectric loss factor, the second dielectric loss factor of the coated polymer material being greater than the first dielectric loss factor of the base polymer material.

[0036] Appendix 2. The coated filament (10) of Appendix 1, wherein the base polymer material has a first melting point and the coating polymer material has a second melting point, the first melting point being within about 20 degrees Celsius of the second melting point.

[0037] Addendum 3. The base polymer material has a first solubility parameter, and the coating polymer material has a second solubility parameter, and the second solubility parameter differs from the first solubility parameter by about 10 J / cc. 0.5 The coated filament (10) according to claim 2, wherein the thickness is within the range of 0.1 to 1.

[0038] Addendum 4. The base polymer material has a first solubility parameter, and the coating polymer material has a second solubility parameter, and the second solubility parameter differs from the first solubility parameter by about 10 J / cc. 0.5 The coated filament (10) according to any one of Appendices 1 to 3, wherein the thickness is within the range of 0.1 to 0.5 mm.

[0039] Appendix 5. The coated filament (10) according to any one of Appendixes 1 to 4, wherein the base polymer material includes polyetherimide and the coating polymer material includes polyvinyl alcohol.

[0040] Appendix 6. The coated filament (10) according to any one of Appendixes 1 to 5, wherein the base polymer layer (8) has a thickness of about 0.1 to about 5 millimeters, and the coating polymer layer (9) has a thickness of about 1 to about 1,000 microns.

[0041] Appendix 7. A method for producing a coated filament (10) for use in an additive manufacturing process, comprising: advancing a polymer filament (2) along a path, the polymer filament (2) being formed from a base polymer material; A liquid paint (7) is applied to an outer surface of the polymer filament (2) at a point on the path, the liquid paint (7) being formed of a coating polymer material; drying the liquid paint (7) on the polymer filaments (2) to form the coated filaments (10), the coated filaments (10) including a base polymer layer (8) formed by the polymer filaments (2) and a coated polymer layer (9) formed by the liquid paint (7) after drying.

[0042] Addendum 8. The base polymer material has a first dielectric loss factor; the coating polymeric material has a second dielectric loss factor; 8. The method of claim 7, wherein the second dielectric loss factor of the coating polymeric material is greater than the first dielectric loss factor of the base polymeric material.

[0043] Clause 9. The base polymer material has a first melting point; the coating polymeric material has a second melting point; 9. The method of claim 7 or 8, wherein the first melting point is within about 20 degrees Celsius of the second melting point.

[0044] Addendum 10. The base polymer material has a first solubility parameter; the coating polymeric material has a second solubility parameter; The second solubility parameter has a difference of about 10 J / cc from the first solubility parameter. 0.5 The method according to any one of Appendices 7 to 9, wherein the reaction is within the range of 0.1 to 0.5 μg / kg.

[0045] Addendum 11. The method according to any one of Addendums 7 to 10, wherein the polymer filament (2) is supported between a first spool (4) and a second spool (12) and the first and second spools (4, 12) are rotated when advancing the polymer filament (2) along the path.

[0046] Addendum 12. The method according to any one of Addendums 7 to 11, wherein when applying the liquid coating material (7) to the outer surface of the polymer filament (2), the polymer filament (2) is advanced by passing the polymer filament (2) through a reservoir (6) that holds the liquid coating material (7).

[0047] Addendum 13. The method of any one of Addendums 7 to 12, wherein the base polymer material comprises polyetherimide and the coating polymer material comprises polyvinyl alcohol.

[0048] Addendum 14. The method according to any one of Addendums 7 to 13, wherein the base polymer layer (8) has a thickness of about 0.1 to about 5 millimeters, and the coating polymer layer (9) has a thickness of about 1 to about 1,000 microns.

[0049] Appendix 15. A method for producing an article by fused filament manufacturing, comprising: forming a coated filament (10), advancing a polymer filament (2) along a path, the polymer filament (2) being formed from a base polymer material; A liquid paint (7) is applied to an outer surface of the polymer filament (2) at a point on the path, the liquid paint (7) being formed of a coating polymer material; The liquid paint (7) on the polymer filament (2) is dried to form the coated filament (10), the coated filament (10) comprising a base polymer layer (8) formed by the polymer filament (2) and a coated polymer layer (9) formed by the liquid paint (7) after drying, the method further comprising: depositing adjacent first and second beads (56, 57) of the coated filament (10) onto a substrate (54); the method further comprising: dielectrically heating at least the coating polymer layer in each of the first bead (56) and the second bead (57) using electromagnetic radiation (64), thereby fusing the first and second beads (56, 57) of the coated filament (10) at an interface region (62).

[0050] Clause 16. The method of clause 15, further comprising melting at least an outer portion of the base polymer layer of each of the first and second beads (56, 57).

[0051] Addendum 17. The base polymer material has a first dielectric loss factor; the coating polymeric material has a second dielectric loss factor; 17. The method of claim 15 or 16, wherein the second dielectric loss factor of the coating polymeric material is greater than the first dielectric loss factor of the base polymeric material.

[0052] Clause 18. The base polymer material has a first melting point; the coating polymeric material has a second melting point; 18. The method according to any one of claims 15 to 17, wherein the first melting point is within 20 degrees Celsius of the second melting point.

[0053] Addendum 19. The base polymer material has a first solubility parameter; the coating polymeric material has a second solubility parameter; The second solubility parameter has a difference of about 10 J / cc from the first solubility parameter. 0.5 19. The method according to any one of claims 15 to 18, wherein the range is within 1 to 20.

[0054] Addendum 20. The method of any one of Addendums 15 to 19, wherein the base polymer material comprises polyetherimide and the coating polymer material comprises polyvinyl alcohol.

[0055] It should be noted that the drawings are not necessarily drawn to scale, and that the examples of the present disclosure may be shown in schematic form. Furthermore, the detailed description is merely exemplary in nature and is not intended to limit the present disclosure or its application or uses. Thus, for convenience of explanation, the present disclosure is shown and described in terms of several exemplary embodiments, but the present disclosure may be implemented in a variety of other types of embodiments and in various other systems and environments.

Claims

1. 1. A coated filament for use in an additive manufacturing process, comprising: a base polymer layer formed from a base polymer material having a first dielectric loss factor represented by a first tan δ value; a coating polymer layer covering the base polymer layer and formed of a coating polymer material having a second dielectric loss factor represented by a second tan δ value, the second dielectric loss factor of the coating polymer material being greater than the first dielectric loss factor of the base polymer material; The coated filament, wherein the second tan δ value is at least 50 times the first tan δ value.

2. 2. The coated filament of claim 1, wherein the base polymeric material has a first melting point and the coating polymeric material has a second melting point, the first melting point being within 20 degrees Celsius of the second melting point.

3. The base polymer material has a first solubility parameter, and the coating polymer material has a second solubility parameter, the second solubility parameter differing from the first solubility parameter by less than 10 J / cc. 0.5 The coated filament according to claim 1 or 2, wherein the thickness is within a range of 1 mm to 100 mm.

4. A coated filament for use in an additive manufacturing process, comprising: a base polymer layer formed from a base polymer material having a first dielectric loss factor; a coating polymer layer covering the base polymer layer and formed by a coating polymer material having a second dielectric loss factor, the second dielectric loss factor of the coating polymer material being greater than the first dielectric loss factor of the base polymer material; A coated filament, wherein the base polymeric material comprises polyetherimide and the coating polymeric material comprises polyvinyl alcohol.

5. 5. The coated filament according to claim 1, wherein the base polymer layer has a thickness of 0.1 to 5 millimeters and the coating polymer layer has a thickness of 1 to 1,000 microns.

6. 1. A method for producing a coated filament for use in an additive manufacturing process, comprising: advancing a polymer filament along a path, the polymer filament being formed from a base polymer material; applying a liquid coating to an exterior surface of the polymer filament at a location along the path, the liquid coating being formed from a coating polymer material; drying the liquid paint on the polymer filaments to form the coated filaments, the coated filaments including a base polymer layer formed by the polymer filaments and a coated polymer layer formed by the liquid paint after drying; the base polymer material has a first dielectric loss factor expressed by a first tan δ value; The method of claim 1, wherein the coating polymeric material has a second dielectric loss factor expressed by a second tan δ value, the second tan δ value being at least 50 times the first tan δ value.

7. 7. The method of claim 6, further comprising supporting the polymer filament between a first spool and a second spool and rotating the first and second spools as the polymer filament is advanced along the path.

8. 8. The method of claim 6 or 7, wherein applying the liquid paint to the outer surface of the polymer filament comprises advancing the polymer filament through a reservoir that holds the liquid paint.

9. A method for producing a coated filament for use in an additive manufacturing process, comprising: advancing a polymer filament along a path, the polymer filament being formed from a base polymer material; applying a liquid coating to an exterior surface of the polymer filament at a location along the path, the liquid coating being formed from a coating polymer material; drying the liquid paint on the polymer filaments to form the coated filaments, the coated filaments including a base polymer layer formed by the polymer filaments and a coated polymer layer formed by the liquid paint after drying; The method, wherein the base polymeric material comprises polyetherimide and the coating polymeric material comprises polyvinyl alcohol.

10. 1. A method for producing an article by fused filament manufacturing, comprising: forming a coated filament, advancing a polymer filament along a path, the polymer filament being formed from a base polymer material; applying a liquid coating to an exterior surface of the polymer filament at a location along the path, the liquid coating being formed from a coating polymer material; forming the coated filament by drying the liquid paint on the polymer filament, the coated filament including a base polymer layer formed by the polymer filament and a coated polymer layer formed by the liquid paint after drying, the method further comprising: depositing adjacent first and second beads of the coated filament onto a substrate; dielectrically heating at least the coating polymer layer in each of the first and second beads using electromagnetic radiation, thereby fusing the first and second beads of the coated filament at an interface region; The method, wherein the base polymeric material comprises polyetherimide and the coating polymeric material comprises polyvinyl alcohol.

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