Building material composition and heat conducting agent for three-dimensional printing

Abstract

Examples of build material compositions and thermally conductive agents for three-dimensional printing are disclosed. An example of a build material composition includes from about 90 wt% to about 99 wt% of thermoplastic polyurethane particles and from about 1 wt% to about 10 wt% of a thermally conductive filler, based on the total weight of the build material composition. Examples of thermal conductive agents include an aqueous carrier and from about 1 wt% to about 10 wt% active thermally conductive filler based on the total weight of the thermal conductive agent. In both examples, the thermally conductive filler is selected from cubic boron nitride and diamond-like carbon.

Description

Background Art

[0001] Three-dimensional (3D) printing is an additive manufacturing process for fabricating 3D printed articles from digital models. 3D printing typically involves applying successive layers of printing materials (such as, build materials, one or more reagents, and / or other (multiple) printing materials) to create the final 3D printed article. This is different from traditional machining processes, which typically rely on removing material to create the final 3D article. 3D printing is commonly used for rapid product prototyping, mold generation, mold master generation, and short-run manufacturing to enable mass personalization and customization of goods. Brief Description of the Drawings

[0002] The features of the examples of the present disclosure will become apparent by reference to the following detailed description and the drawings, in which like reference numerals correspond to similar but possibly different components. For the sake of brevity, reference numerals or features having a previously described function may or may not be described in combination with other drawings in which the reference numerals or features appear.

[0003] Figure 1 is a schematic diagram showing an example of a 3D printing method.

[0004] Figure 2 is a schematic diagram showing another example of a 3D printing method.

[0005] Figure 3 is by Figure 1 and Figure 2 is an enlarged schematic cross-sectional view of a 3D printed article created by the 3D printing method.

[0006] Figure 4 is a bar graph showing the thermal conductivity (W / (m·K), Y-axis) of four samples of a build material composition comprising thermoplastic polyurethane and a thermally conductive filler and two samples of a comparative build material composition comprising only thermoplastic polyurethane determined at multiple temperatures.

[0007] Figure 5 is a graph showing the melting enthalpy (J / g, Y-axis) determined for all six samples.

[0008] Figure 6 is a graph showing the crystallization enthalpy (J / g, Y-axis) determined for all six samples.

[0009] Figure 7 is a graph showing the thermal window (°C, Y-axis) of all six samples.

[0010] Figure 8 is a bar graph showing the Young's modulus (MPa, Y-axis) of all six samples.

[0011] Figure 9 It is a bar graph showing the elongation at break (%, Y-axis) of all six samples.

[0012] Figure 10 It is a bar graph showing the heat capacity (J / g·C, Y-axis) of two samples of a comparative build material composition containing polypropylene powder and cubic boron nitride thermal conductive filler and one sample of a comparative build material composition containing only polypropylene powder, determined at multiple temperatures.

[0013] Figure 11 It is a bar graph showing the heat capacity (J / g·C, Y-axis) of two samples of a comparative build material composition containing polypropylene powder and diamond-like carbon thermal conductive filler and one sample of a comparative build material composition containing only polypropylene powder, determined at multiple temperatures. Detailed Description

[0014] The performance of 3D printing processes or techniques typically depends at least in part on the thermal properties of the 3D printing material(s) used in the process. For example, the time required to melt the polymer in the build material composition, the time allowed for the melted polymer to fully melt, and the heat transfer between the patterned build material compositions each play a role in the overall performance of the 3D printing process. One way to control the thermal properties of 3D printing materials involves reformulating the polymer of the build material composition. However, reformulating the polymer can be inefficient and is typically limited by the capabilities of the reformulation process used. Thus, controlling the thermal properties of 3D printing material(s) to improve the performance of 3D printing processes remains a challenge.

[0015] The inventors of the present disclosure have found that by introducing a thermal conductive filler together with the polymer in the build material composition or introducing the thermal conductive filler into the build material composition during patterning, the thermal properties of the polymer of the build material composition can be controlled. The presence of the filler improves 3D printing performance without relying solely on the thermal properties of the polymer. As shown in the following examples section, improvements in the operating thermal window, melting enthalpy, crystallization enthalpy, and thermal conductivity were achieved with build material compositions comprising a thermoplastic polyurethane (TPU) polymer and a thermal conductive filler selected from cubic boron nitride and diamond-like carbon. The build material compositions disclosed herein exhibit improved thermal properties without changing the chemical properties of the thermoplastic polyurethane by including a thermal conductive filler. In other words, improved thermal properties are achieved without reformulating the polymer of the build material. Additionally, the thermal conductive filler present in the build material composition does not have an adverse effect on the mechanical properties of the 3D printed article or part.

[0016] The present disclosure provides two embodiments, and provides a number of examples for each of the two embodiments. The first embodiment ("Embodiment 1") includes a building material composition containing a thermal conductive filler, and a 3D printing kit and a 3D printing method including or utilizing the building material composition. The second embodiment ("Embodiment 2") includes a thermal conductive agent containing a thermal conductive filler, and a 3D printing kit and a 3D printing method including or utilizing the thermal conductive agent. Embodiment 1 will be described first, and then Embodiment 2 will be described.

[0017] Throughout the present disclosure, the weight percentage referred to as "wt% active" refers to the loading amount of the active component of the stock preparation present in, for example, a thermal conductive agent, a melting agent, a refining agent, etc. For example, a thermal conductive filler (such as, cubic boron nitride) may be present in an aqueous preparation (such as, a stock solution or dispersion) before being incorporated into the carrier of the thermal conductive agent. In this example, the wt% active of the cubic boron nitride takes into account the loading amount (by weight percentage) of the cubic boron nitride solid present in the thermal conductive agent, without considering the weight of other components (such as, water, etc.) present in the stock solution or dispersion together with the cubic boron nitride solid. The term "wt%" without the term "active" refers to the loading amount of 100% active component excluding other inactive components.

[0018] Embodiment 1

[0019] In Embodiment 1, the thermal conductive filler is incorporated into the building material composition. During 3D printing, the building material composition is patterned using a melting agent and exposed to electromagnetic radiation to initiate the coalescence of the polymer in the building material composition.

[0020] Building material composition

[0021] In Embodiment 1, the building material composition for three-dimensional printing includes: thermoplastic polyurethane particles, present in an amount of about 90 wt% to about 99 wt% based on the total weight of the building material composition; and a thermal conductive filler, present in an amount of about 1 wt% to about 10 wt% based on the total weight of the building material composition, the thermal conductive filler being selected from the group consisting of cubic boron nitride and diamond-like carbon.

[0022] The building material composition includes thermoplastic polyurethane particles. Thermoplastic polyurethane is a block copolymer including an alternating sequence of hard segments and soft segments, and is a reaction product of an isocyanate component and an isocyanate-reactive component.

[0023] The isocyanate component is selected from aliphatic, cycloaliphatic, and aromatic isocyanates. In an example, the isocyanate component is a diisocyanate such as diphenylmethane diisocyanate (MDI), polymeric diphenylmethane diisocyanate (PMDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and combinations thereof. The isocyanate component forms each hard segment of the block copolymer. The hard segments are responsible for various physical properties of the thermoplastic polyurethane, including hardness, scratch resistance, and impact strength.

[0024] The isocyanate-reactive component is a polyol such as a diol, triol, and ethylene glycol. The polyol can be selected from aliphatic polyols, cycloaliphatic polyols, aromatic polyols, and heterocyclic polyols. Examples of suitable isocyanate-reactive components include polyether polyols and polyester polyols. The isocyanate-reactive component forms each soft segment of the block copolymer. The soft segments are at least responsible for the flexibility and elastomeric properties of the thermoplastic polyurethane. The presence of the soft segments in the thermoplastic polyurethane enables 3D printed articles formed from the construction material composition to be used in products such as footwear, sports protection equipment, orthotics, orthotic models, automotive interior components, various industrial tools, and the like, as well as molded fiber products such as protective packaging products, beverage containers, food service trays, and the like. Other similar products are also contemplated.

[0025] The thermoplastic polyurethane can be formed in the presence of a suitable catalyst and one or more additives such as one or more crosslinking agents and / or chain extenders. The (multiple) additives can be introduced into the isocyanate component and / or the isocyanate-reactive component before combining the isocyanate component and the isocyanate-reactive component to form a reaction product. Alternatively, the (multiple) additives can be introduced as a separate component after the isocyanate component and the isocyanate-reactive component have been combined.

[0026] In an example, the thermoplastic polyurethane particles have a particle size of from about 10 μm to about 200 μm. In another example, the thermoplastic polyurethane particles have a particle size of from about 50 μm to about 120 μm. In yet another example, the thermoplastic polyurethane particles have a particle size of from about 70 μm to about 90 μm.

[0027] As used herein, the term "particle size" refers to the value of the diameter of spherical particles, or in the case of non-spherical particles, can refer to the longest dimension of the particle. The particle size can be represented as a Gaussian distribution or a Gaussian-like distribution (or a normal distribution or a normal-like distribution). A Gaussian-like distribution is a distribution curve whose shape may appear Gaussian but may be slightly skewed in one direction or the other (towards the smaller end of the particle size distribution range or towards the larger end of the particle size distribution range). Thus, for example, an exemplary Gaussian-like distribution of thermoplastic polyurethane particles can be characterized using "D10", "D50", and "D90" particle size distribution values, where D10 refers to the particle size at the 10th percentile, D50 refers to the particle size at the 50th percentile, and D90 refers to the particle size at the 90th percentile. For example, a D50 value of 80 μm means that 50% of the particles (by number or volume) have a particle size greater than 80 μm, and 50% of the particles have a particle size less than 80 μm. The particle size distribution values may not be related to a Gaussian distribution curve, but in one example of the present disclosure, the thermoplastic polyurethane particles can have a Gaussian distribution, or more typically a Gaussian-like distribution with an offset peak at approximately D50. In fact, a true Gaussian distribution generally does not exist because there may be some skewness, but the Gaussian-like distribution can still be considered the "Gaussian" distribution used in practice.

[0028] In the example, the thermoplastic polyurethane particles are provided in the form of a thermoplastic polyurethane powder. An example of a suitable thermoplastic polyurethane powder is one that can be obtained from BASF Corporation (Florham Park, New Jersey) TPU01.

[0029] The thermoplastic polyurethane particles can have a melting range of about 120 °C to about 150 °C. Other types of thermoplastic polyurethane particles can have a melting range of about 130 °C to about 250 °C.

[0030] The build material composition further includes a thermally conductive filler. As previously described, the thermally conductive filler is incorporated into the build material composition to improve the thermal properties (e.g., thermal conductivity) of the thermoplastic polyurethane. The improvement in thermal properties is achieved without changing the chemical properties of the thermoplastic polyurethane (e.g., reformulating the thermoplastic polyurethane). Additionally, the thermally conductive filler does not have an adverse effect on the mechanical properties of the 3D printed article created by the 3D printing method (described in detail below) that utilizes the build material composition. In the example, the thermally conductive filler is selected from the group consisting of cubic boron nitride and diamond-like carbon.

[0031] Cubic boron nitride (c-BN) is an allotropic crystalline form of boron nitride and has a zinc blende crystal structure similar to that of diamond. Cubic boron nitride is one of the hardest (in terms of material properties) materials available, second only to diamond, and is the most stable among the various allotropes of boron nitride. In addition, cubic boron nitride has better thermal and chemical stability than diamond.

[0032] Cubic boron nitride can be obtained naturally, or it can also be synthesized. If synthesized, cubic boron nitride can be formed by treating hexagonal boron nitride (h-BN) at high temperature (e.g., about 1730 °C to about 3230 °C) and high pressure (e.g., about 5 GPa to about 18 GPa), similar to the synthesis used to produce synthetic diamond from graphite. In some cases, a catalyst can be used.

[0033] Diamond-like carbon (DLC) is an amorphous carbon material with a hexagonal layered chemical structure similar to that of graphite, except that diamond-like carbon has a higher amount of sp 3 bonding and a lower amount of sp 2 bonding. Diamond-like carbon can be synthesized from graphite or other carbon-based materials C x H y using various synthesis techniques.

[0034] In addition, diamond-like carbon has material properties similar to those of diamond. For example, the density of diamond-like carbon has been measured to be about 3 g / cm 3 , while the density of diamond has been measured to be about 3.52 g / cm 3 . In another example, the hardness of diamond-like carbon (measured using nanoindentation on a film with a thickness less than 1 μm under a load of less than 1 N) has been measured to be about 10 GPa to about 90 GPa, while the hardness of diamond (measured using the same nanoindentation method) is about 90 GPa to about 100 GPa. It should be understood that the hardness of diamond-like carbon can vary at least in part depending on the ratio of sp 3 bonding and sp 2 bonding and the amount of hydrogen present in the chemical structure.

[0035] In an example, the thermally conductive filler (cubic boron nitride or diamond-like carbon) is in solid form. The solid form can be a powder including nanoparticles of cubic boron nitride or diamond-like carbon. Thus, in some examples, the thermally conductive filler is further defined as thermally conductive nanoparticles. Nanoparticles (i.e., having a particle size in the range of 1 nm to less than 1 μm) are desirable, in part because they are at least one order of magnitude smaller than the thermoplastic polyurethane particles and thus are minimally or non-destructive to the blend with the thermoplastic polyurethane particles.

[0036] In the case where the thermally conductive nanoparticles are cubic boron nitride nanoparticles, the cubic boron nitride nanoparticles have a particle size of, for example, about 70 nm to about 800 nm. In another example, the cubic boron nitride nanoparticles have a particle size of about 100 nm to about 500 nm. In the case where the thermally conductive nanoparticles are diamond-like carbon nanoparticles, the diamond-like carbon nanoparticles have a particle size of, for example, about 80 nm to about 600 nm. In another example, the diamond-like carbon nanoparticles have a particle size of about 100 nm to about 250 nm.

[0037] As described above, the construction material composition comprises or includes thermoplastic polyurethane particles and a thermally conductive filler. In an example, the construction material composition consists of thermoplastic polyurethane and a thermally conductive filler. In this particular example, the construction material composition does not contain any additional components. Thus, in this example, the total weight of the construction material composition consists of thermoplastic polyurethane particles and a thermally conductive filler.

[0038] However, in other examples, the construction material composition can include one or more additives such as antioxidants, whitening agents, antistatic agents, flow aids, or combinations thereof. Although several examples of these additives are provided, it should be understood that these additives are selected to be thermally stable (i.e., will not decompose) at the 3D printing temperature.

[0039] An antioxidant(s) can be added to the construction material composition to prevent or slow down the reduction in the molecular weight of the thermoplastic polyurethane particles and / or to prevent or slow down the discoloration (e.g., yellowing) of the thermoplastic polyurethane particles by preventing or slowing down the oxidation of the thermoplastic polyurethane particles. In some examples, the thermoplastic polyurethane particles may discolor when reacting with oxygen, and this discoloration may cause the construction material composition to discolor. The antioxidant can be selected to minimize the discoloration. In some examples, the antioxidant can be a free radical scavenger. In these examples, the antioxidant can include 1098 (Benzeneacetamide, N,N'-1,6-hexanediylbis(3,5-bis(1,1-dimethylethyl)-4-hydroxy)) 254 (a mixture of 40% triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl), polyvinyl alcohol, and deionized water) and / or other sterically hindered phenols. In other examples, the antioxidant can include phosphites and / or organic sulfides (e.g., thioesters). The antioxidant can be in the form of fine particles (e.g., with an average particle size of 5 μm or less). In an example, based on the total weight of the build material composition, the antioxidant can be included in the build material composition in an amount in the range of about 0.01 wt% to about 5 wt%. In other examples, based on the total weight of the build material composition, the antioxidant can be included in the build material composition in an amount in the range of about 0.01 wt% to about 2 wt% or about 0.2 wt% to about 1 wt%.

[0040] A (multi)whitening agent can be added to the build material composition to make the L of the build material composition * closer to 100 (white) and / or improve visibility. Examples of suitable whitening agents include titanium dioxide (TiO2), zinc oxide (ZnO), calcium carbonate (CaCO3), zirconium dioxide (ZrO2), aluminum oxide (Al2O3), silicon dioxide (SiO2), boron nitride (BN), and combinations thereof. In some examples, stilbene derivatives can be used as whitening agents and brightening agents. In these examples, the (multi)temperature of the 3D printing process can be selected such that the stilbene derivative remains stable (i.e., the 3D printing temperature does not cause thermal decomposition of the stilbene derivative). Based on the total weight of the build material composition, any example of the whitening agent can be included in the build material composition in an amount in the range of greater than 0 wt% to about 10 wt%.

[0041] A (multi)antistatic agent can be added to the build material composition to inhibit triboelectrification. Examples of suitable antistatic agents include fatty amines (which can be ethoxylated), fatty amides, quaternary ammonium salts (e.g., dodecyl trimethyl ammonium chloride or cocamidopropyl betaine), phosphate esters, polyethylene glycol esters, or polyols. Some suitable commercially available antistatic agents include FA 38 (natural-based ethoxylated alkylamine), FE2 (fatty acid ester), and HS1 (alkane sulfonate), each of which can be obtained from Clariant Int. Ltd. In an example, based on the total weight of the build material composition, the antistatic agent is added in an amount in the range of greater than 0 wt% to less than 5 wt%.

[0042] One or more glidants can be added to improve the coating fluidity of the build material composition. Glidants can be particularly beneficial when the build material composition has an average particle size of less than 25 μm. Glidants improve the fluidity of the build material composition by reducing friction, lateral resistance, and frictional charge accumulation (by increasing particle conductivity). Examples of suitable glidants include aluminum oxide (Al2O3), tricalcium phosphate (E341), powdered cellulose (E460(ii)), magnesium stearate (E470b), sodium bicarbonate (E500), sodium ferrocyanide (E535), potassium ferrocyanide (E536), calcium ferrocyanide (E538), bone phosphate (E542), sodium silicate (E550), silicon dioxide (E551), calcium silicate (E552), magnesium trisilicate (E553a), talc (E553b), sodium aluminosilicate (E554), potassium aluminum silicate (E555), calcium aluminosilicate (E556), bentonite (E558), aluminum silicate (E559), stearic acid (E570), and polydimethylsiloxane (E900). In the examples, the glidant is added in an amount in the range of greater than 0 wt% to less than 5 wt% based on the total weight of the build material composition.

[0043] As described above, the thermoplastic polyurethane particles are provided in the form of micron-sized particles and the thermally conductive filler is provided in the form of nano-sized particles, and thus each of these components is in powder form. The powders are combined to form a dry blend of the thermoplastic polyurethane particles and the thermally conductive filler. In one example, the thermally conductive filler includes thermally conductive nanoparticles and the build material composition is a dry blend of the thermoplastic polyurethane particles and the thermally conductive nanoparticles. The dry blend can be formed by mixing the dry thermoplastic polyurethane particles (or powder) and the dry thermally conductive filler (or powder) in a mixer or blender suitable for combining dry components. In the examples, the dry blend is a homogeneous mixture of the thermoplastic polyurethane particles and the thermally conductive filler. It should be understood that the term "dry blend" can be used interchangeably with the term "powder blend". Additionally, as a dry blend or powder blend, the build material composition is considered a solid.

[0044] When using one or more of the additives for the build material composition described herein, the additive(s) is / are dry blended with the thermoplastic polyurethane particles and the thermally conductive filler.

[0045] In any exemplary build material composition of Embodiment 1, thermoplastic polyurethane particles are present in the build material composition in an amount of, for example, more than 85 wt%, based on the total weight of the build material composition. In another example, the thermoplastic polyurethane particles are present in an amount of about 90 wt% to about 99 wt%, based on the total weight of the build material composition. In yet another example, the thermoplastic polyurethane particles are present in an amount of about 94 wt% to about 96 wt%, based on the total weight of the build material composition. In a specific example, the thermoplastic polyurethane is present in an amount of about 95 wt%, based on the total weight of the build material composition.

[0046] In any exemplary build material composition of Embodiment 1, a thermally conductive filler is present in the build material composition in an amount of, for example, up to about 15 wt%, based on the total weight of the build material composition. In another example, the thermally conductive filler is present in an amount of about 1 wt% to about 10 wt%, based on the total weight of the build material composition. In yet another example, the thermally conductive filler is present in an amount of about 4 wt% to about 6 wt%, based on the total weight of the build material composition. In a specific example, the thermally conductive filler is present in an amount of about 5 wt%, based on the total weight of the build material composition. It should be understood that it is not desirable to include the thermally conductive filler in an amount exceeding or higher than 15 wt%, based on the total weight of the build material composition. A higher loading of the thermally conductive filler may have a greater impact on the meltability, which may in turn affect the parameters used in the 3D printing process. By controlling the thermal conductivity of the build material composition using the thermally conductive filler described herein, the printing parameters (e.g., shortening the melting time, reducing the melting power, etc.) can be simplified and thus the process can be improved.

[0047] The build material composition described with reference to Embodiment 1 can be used in a 3D printing method. A 3D printing system 100 (such as the system shown in Figure 1 can be used to implement the 3D printing method. The method can include selectively applying (in accordance with a 3D digital model for the 3D printed article being formed) a fusing agent to pattern a build material layer formed from the build material composition and exposing the entire patterned layer to electromagnetic radiation. In this method, the patterned region of the build material composition (which in some cases is less than the entire layer) coalesces and cures to become a layer of the 3D printed article. The fusing agent that can be used in such a printing method will now be described.

[0048] Flux

[0049] In 3D printing methods, various fusing agents can be used, and each fusing agent contains an energy absorber. In some examples, the energy absorber exhibits absorbency at certain wavelengths at least in the range of 100 nm to 4000 nm. Unless otherwise specified, the term "absorbency" means that 80% or more of the applied radiation having wavelengths within the specified range is absorbed by the energy absorber. Additionally, unless otherwise specified, the term "transparency" means that 25% or less of the applied radiation having wavelengths within the specified range is absorbed by the energy absorber. Several examples of suitable fusing agents are described below.

[0050] Flux #1

[0051] One example of a fusing agent ("Fusing Agent #1") is referred to as a core fusing agent, and the energy absorber in the core fusing agent exhibits absorbency at least at wavelengths from 400 nm to 780 nm (e.g., in the visible light region). The energy absorber in the core fusing agent can also absorb energy in the infrared region (e.g., 800 nm to 4000 nm). During 3D printing, the absorbency of the energy absorber generates heat suitable for coalescing / fusing the build material composition in contact therewith, which enables the 3D printed article to have mechanical integrity and relatively uniform mechanical properties (e.g., strength, elongation at break, etc.). However, this absorbency also causes the 3D printed article (or 3D printed article region) to exhibit an overly dark color, such as dark gray or black.

[0052] Examples of the energy absorber in the core fusing agent can be infrared light absorbing colorants. In an example, the energy absorber is a near-infrared light absorbing colorant. Any near-infrared colorant (e.g., near-infrared colorants produced by Fabricolor Holding, Int'l LLC, Eastman Kodak Company, BASF SE, Yamamoto Chemicals Inc.) can be used in the core fusing agent. As an example, the core fusing agent can be a printing liquid formulation comprising carbon black as the energy absorber. Examples of such printing liquid formulations are commercially known as CM997A, 516458, C18928, C93848, C93808, etc., all of which are available from HP Inc.

[0053] As another example, the core fusing agent can be a printing liquid formulation comprising a near-infrared absorbing dye as the active material. Examples of such printing liquid formulations are described in U.S. Patent No. 9,133,344, which is incorporated herein by reference in its entirety. Some examples of near-infrared absorbing dyes are water-soluble near-infrared absorbing dyes selected from the group consisting of and mixtures thereof:

[0054]

[0055]

[0056] In the above-mentioned preparation, M can be a divalent metal atom (e.g., copper, etc.), or if the metal is higher than divalent (e.g., indium, etc.), it can have an OSO3Na axial group filling any unfilled valence state. R can be hydrogen or any C1-C8 alkyl group (including substituted alkyl groups and unsubstituted alkyl groups), and Z can be a counterion such that the total charge of the near-infrared absorbing dye is neutral. For example, the counterion can be sodium, lithium, potassium, NH4 + etc.

[0057] Some other examples of near-infrared absorbing dyes are hydrophobic near-infrared absorbing dyes and mixtures thereof selected from the group consisting of:

[0058]

[0059]

[0060] . For hydrophobic near-infrared absorbing dyes, M can be a divalent metal atom (e.g., copper, etc.), or if the metal is higher than divalent, it can include a metal having an axial group of Cl, Br, or OR' (R' = H, CH3, COCH3, COCH2COOCH3, COCH2COCH3) filling any unfilled valence state, and R can be hydrogen or any C1-C8 alkyl group (including substituted alkyl groups and unsubstituted alkyl groups).

[0061] Other near-infrared absorbing dyes or pigments can be used in the core flux. Some examples include anthraquinone dyes or pigments, metal dithiolene dyes or pigments, cyanine dyes or pigments; perylene diimide dyes or pigments, croconic acid dyes or pigments, pyrilium or thiopyrilium dyes or pigments, boron-dipyrromethene dyes or pigments, or azaboron-dipyrromethene dyes or pigments.

[0062] Anthraquinone dyes or pigments and metal (e.g., nickel) dithiolene dyes or pigments can have the following structures respectively:

[0063]

[0064] wherein R in the anthraquinone dye or pigment can be hydrogen or any C1-C8 alkyl group (including substituted alkyl groups and unsubstituted alkyl groups), and R in the dithiolene can be hydrogen, COOH, SO3, NH2, any C1-C8 alkyl group (including substituted alkyl groups and unsubstituted alkyl groups), etc.

[0065] The cyanine dyes or pigments and the perylene diimide dyes or pigments can respectively have the following structures:

[0066]

[0067] Wherein R in the perylene diimide dyes or pigments can be hydrogen or any C1-C8 alkyl group (including substituted alkyl groups and unsubstituted alkyl groups).

[0068] The croconic acid dyes or pigments and the pyranium or thiopyranium dyes or pigments can respectively have the following structures:

[0069]

[0070]

[0071] The boron-dipyrromethene dyes or pigments and theaza-boron-dipyrromethene dyes or pigments can respectively have the following structures:

[0072]

[0073] Other suitable near-infrared absorbing dyes can include amino dyes, tetraaryldiamine dyes, phthalocyanine dyes and other dyes.

[0074] Other near-infrared absorbing materials include conjugated polymers (i.e., polymers having a backbone with alternating double bonds and single bonds), such as poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), polythiophene, poly(p-phenylene sulfide), polyaniline, poly(pyrrole), poly(acetylene), poly(p-styrene), poly(p-phenylene) or combinations thereof.

[0075] Based on the total weight of the core flux, the amount of the energy absorber present in the core flux is greater than 0 wt% active to about 40 wt% active. In other examples, the amount of the active material in the core flux is about 0.3 wt% active to 30 wt% active, about 1 wt% active to about 20 wt% active, about 1.0 wt% active to up to about 10.0 wt% active, or greater than 4.0 wt% active to up to about 15.0 wt% active. It is believed that these active material loadings provide a balance between the core flux having jetting reliability and the heat and / or radiation absorbance efficiency.

[0076] Flux #2

[0077] Another example of a fusing agent (“fusing agent #2”) is referred to herein as a primer fusing agent or a low-tone fusing agent, and the energy absorber in the primer fusing agent is a plasmon resonance absorber that is absorptive at wavelengths from 100 nm to 400 nm or from 800 nm to 4000 nm and transparent at wavelengths from 400 nm to 780 nm. This absorptivity and transparency allow the primer fusing agent to absorb sufficient radiation to coalesce / fuse the build material composition in contact with the primer fusing agent while rendering the 3D printed article (or 3D printed article region) white or slightly colored.

[0078] Some examples of primer fusing agents are dispersions that include an energy absorber that is absorptive at wavelengths from 800 nm to 4000 nm and transparent at wavelengths from 400 nm to 780 nm. The absorptivity of such an energy absorber can be the result of a plasmon resonance effect. Electrons associated with the atoms of the energy absorber can be collectively excited by radiation, resulting in a collective oscillation of the electrons. The wavelength at which these electrons can be collectively excited and oscillated depends on the number of electrons present in the energy absorber particles, which in turn depends on the size of the energy absorber particles. The energy of the electrons that can collectively oscillate the particles is low enough that very small particles (e.g., 1 nm to 100 nm) can absorb radiation at wavelengths several times the particle size (e.g., 8 to 800 times or greater). The use of these particles allows the primer fusing agent to be inkjet printable and electromagnetically selective (e.g., absorptive at wavelengths from 800 nm to 4000 nm and transparent at wavelengths from 400 nm to 780 nm).

[0079] In an example, the energy absorber of the primer fusing agent has an average particle size greater than 0 nm to less than 220 nm. In another example, the energy absorber has an average particle size greater than 0 nm to 120 nm. In yet another example, the energy absorber has an average particle size of about 10 nm to about 200 nm.

[0080] In an example, the energy absorber of the primer fusing agent is an inorganic pigment. Examples of suitable inorganic pigments include lanthanum hexaboride (LaB6), tungsten bronze (AWO3), indium tin oxide (In2O3:SnO2, ITO), antimony tin oxide (Sb2O3:SnO2, ATO), titanium nitride (TiN), aluminum zinc oxide (AZO), ruthenium oxide (RuO2), fayalite (A x Fe y Si2O6, where A is Ca or Mg, x = 1.5 - 1.9, y = 0.1 - 0.5), modified iron phosphate (A x Fe y PO4), modified copper phosphate (A x Cu y POz ) and modified copper pyrophosphate (A x Cu y P2O7). Tungsten bronze may be alkali-doped tungsten oxide. Examples of suitable alkali dopants (i.e., A in x WO3) may be cesium, sodium, potassium, or rubidium. In an example, the alkali-doped tungsten oxide may be doped in an amount greater than 0 mol% to about 0.33 mol% based on the total mol% of the alkali-doped tungsten oxide. Suitable modified iron phosphate (A x Fe y PO) may include iron copper phosphate (A = Cu, x = 0.1 - 0.5, and y = 0.5 - 0.9), iron magnesium phosphate (A = Mg, x = 0.1 - 0.5, and y = 0.5 - 0.9), and iron zinc phosphate (A = Zn, x = 0.1 - 0.5, and y = 0.5 - 0.9). For modified iron phosphate, it will be understood that the amount of phosphate may vary based on charge balance with the cation. Suitable modified copper pyrophosphate (A x Cu y P2O7) includes iron copper pyrophosphate (A = Fe, x = 0 - 2, and y = 0 - 2), magnesium copper pyrophosphate (A = Mg, x = 0 - 2, and y = 0 - 2), and zinc copper pyrophosphate (A = Zn, x = 0 - 2, and y = 0 - 2). Combinations of inorganic pigments may also be used.

[0081] Based on the total weight of the primer flux, the amount of the energy absorber present in the primer flux is greater than 0 wt% active to about 40 wt% active. In other examples, the amount of the energy absorber in the primer flux is about 0.3 wt% active to 30 wt% active, about 1 wt% active to about 20 wt% active, about 1.0 wt% active to up to about 10.0 wt% active, or greater than 4.0 wt% active to up to about 15.0 wt% active. It is believed that these energy absorber loadings provide a balance between a primer flux having jetting reliability and heat and / or radiation absorbance efficiency.

[0082] In some instances, the energy absorber of the primer flux may be dispersed with a dispersant. Thus, the dispersant helps to evenly distribute the energy absorber throughout the primer flux. Examples of suitable dispersants include polymeric or small molecule dispersants, charged groups attached to the surface of the energy absorber, or other suitable dispersants. Some specific examples of suitable dispersants include water-soluble acrylic polymers (e.g., K7028 available from Lubrizol Corporation), water-soluble styrene-acrylic copolymer / resin (e.g., 296 available from BASF Corp.), 671, 678, 680, 683, 690, etc.), high molecular weight block copolymers having pigment - affinity groups (e.g., those available from BYK Additives and Instruments) -190) or water - soluble styrene - maleic anhydride copolymers / resins.

[0083] Whether a single dispersant or a combination of multiple dispersants is used, the total amount of the (multiple) dispersants in the primer flux can be from about 10% to about 200% of the weight of the energy absorber in the primer flux. For example, if the energy absorber accounts for 20 wt% of the flux, the dispersant can be in the range of about 2 wt% active (i.e., 10% of 20 wt%) to about 40 wt% active (i.e., 200% of 20%).

[0084] Silane coupling agents can also be added to the primer flux to aid in bonding organic (e.g., dispersants) and inorganic (e.g., pigments) materials. Examples of suitable silane coupling agents include those manufactured by Momentive A series.

[0085] Whether a single silane coupling agent or a combination of multiple silane coupling agents is used, the total amount of the (multiple) silane coupling agents in the primer flux, based on the weight of the energy absorber in the primer flux, can be from about 0.1 wt% active to about 50 wt% active. In an example, the total amount of the (multiple) silane coupling agents in the primer flux, based on the weight of the energy absorber, is from about 1 wt% active to about 30 wt% active. In another example, the total amount of the (multiple) silane coupling agents in the primer flux, based on the weight of the energy absorber, is from about 2.5 wt% active to about 25 wt% active.

[0086] An example of the primer flux includes cesium tungsten oxide (CTO) nanoparticles as an energy absorber. The CTO nanoparticles have the formula Cs x WO3, where 0 < x < 1. The cesium tungsten oxide nanoparticles can make the primer flux light blue. The intensity of the color may depend at least in part on the amount of CTO nanoparticles in the primer flux. When it is desired to form a white outer layer on a 3D - printed object, fewer CTO nanoparticles can be used in the primer flux to achieve white. In an example, based on the total weight of the primer flux, the CTO nanoparticles can be present in the primer flux in an amount from about 1 wt% active to about 20 wt% active.

[0087] The average particle size of the CTO nanoparticles can be from about 1 nm to about 40 nm. In some examples, the average particle size of the CTO nanoparticles can be from about 1 nm to about 15 nm, or from about 1 nm to about 10 nm. The upper end values of the particle size range (e.g., about 30 nm to about 40 nm) may be less desirable because these particles may be more difficult to stabilize.

[0088] This example of the primer fluxing agent can also include an zwitterionic stabilizer. The zwitterionic stabilizer can improve the stability of this example of the primer fluxing agent. Although the zwitterionic stabilizer has an overall neutral charge, at least one region of the molecule has a positive charge (e.g., an amino group) and at least another region of the molecule has a negative charge. The CTO nanoparticles can carry a slightly negative charge. The zwitterionic stabilizer molecules can be oriented around the slightly negatively charged CTO nanoparticles, where the positively charged region of the zwitterionic stabilizer molecule is closest to the CTO nanoparticles and the negatively charged region of the zwitterionic stabilizer molecule is farthest from the CTO nanoparticles. Then, the negative charge of the negatively charged region of the zwitterionic stabilizer molecule may cause the CTO nanoparticles to repel each other. The zwitterionic stabilizer molecules can form a protective layer around the CTO nanoparticles and prevent the CTO nanoparticles from coming into direct contact with each other and / or increase the distance between the particle surfaces (e.g., increase the distance by about 1 nm to about 2 nm). Therefore, the zwitterionic stabilizer can prevent the CTO nanoparticles from agglomerating and / or precipitating in the primer fluxing agent.

[0089] Examples of suitable zwitterionic stabilizers include C2 - C8 betaines, C2 - C8 aminocarboxylic acids with a solubility of at least 10 g in 100 g of water, taurine, and combinations thereof. Examples of C2 - C8 aminocarboxylic acids include β-alanine, γ-aminobutyric acid, glycine, and combinations thereof.

[0090] Based on the total weight of the primer fluxing agent, the zwitterionic stabilizer can be present in the primer fluxing agent in an amount of about 2 wt% active to about 35 wt% active. When the zwitterionic stabilizer is a C2 - C8 betaine, the C2 - C8 betaine can be present in an amount of about 8 wt% to about 35 wt% active based on the total weight of the primer fluxing agent. When the zwitterionic stabilizer is a C2 - C8 aminocarboxylic acid, the C2 - C8 aminocarboxylic acid can be present in an amount of about 2 wt% active to about 20 wt% active based on the total weight of the primer fluxing agent. When the zwitterionic stabilizer is taurine, taurine can be present in an amount of about 2 wt% active to about 35 wt% active based on the total weight of the primer fluxing agent.

[0091] In this example, the weight ratio of the CTO nanoparticles to the zwitterionic stabilizer can be from 1:10 to 10:1; or the weight ratio of the CTO nanoparticles to the zwitterionic stabilizer can be 1:1.

[0092] Flux #3

[0093] Another example of a fusing agent (“fusing agent #3”) is referred to herein as an ultraviolet (UV) light fusing agent, and the energy absorber in the UV fusing agent is a molecule or compound that is absorptive at wavelengths from 100 nm to 400 nm. These energy absorbers efficiently absorb UV radiation, convert the absorbed UV radiation into heat energy, and facilitate the transfer of heat energy to the build material composition to cause the build material composition to coalesce.

[0094] The UV fusing agent can be used with a narrow-band emission source (e.g., a UV light-emitting diode (LED)), which reduces the photon energy bands to which the unpatterned build material is exposed and thus may absorb. This can result in a more precise object shape and reduced rough edges. Some UV energy absorbers are substantially colorless and can thus produce 3D objects that are much lighter in color (e.g., white, off-white, or even translucent) than infrared (IR) and / or visible radiation absorbers.

[0095] Some examples of UV energy absorbers suitable for use in the UV fusing agent include B vitamins and / or B vitamin derivatives. Any water-soluble B vitamin and / or B vitamin derivative that is absorptive at wavelengths from about 340 nm to about 415 nm can be used in the UV light fusing agent. As used herein, the phrase “absorptive at wavelengths from about 340 nm to about 415 nm” means that the B vitamin or B vitamin derivative exhibits maximum absorbance at wavelengths within the given range and / or has an absorbance of about 0.1 (a transmittance of about 80% or less) at one or more wavelengths within the given range. Some B vitamins or B vitamin derivatives have a lower absorbance. When these B vitamins or B vitamin derivatives are combined with a higher intensity and / or higher dose (where dose = intensity * × radiation time), they can still produce adequate coalescence and fusion.

[0096] Examples of suitable B vitamins include riboflavin (vitamin B2), pantothenic acid (vitamin B5), pyridoxine (one form of vitamin B6), pyridoxamine (another form of vitamin B6), biotin (vitamin B7), folic acid (synthetic form of vitamin B9), cyanocobalamin (synthetic form of vitamin B12), and combinations thereof. Examples of suitable B vitamin derivatives include flavin mononucleotide, pyridoxal phosphate hydrate, pyridoxal hydrochloride, pyridoxine hydrochloride, and combinations thereof. Any combination of one or more B vitamins and one or more B vitamin derivatives can also be used. For example, this may be desirable when the absorbance rate of one vitamin or vitamin derivative is low.

[0097] The amount of B vitamins and / or B vitamin derivatives present in the UV light fusing agent will depend in part on their solubility in water and their effect on the ejectability of the fusing agent. When the solubility limit of the B vitamins and / or B vitamin derivatives is low, the B vitamins and / or B vitamin derivatives can be present in an amount of from about 1 wt% active to about 5 wt% active based on the total weight of the fusing agent. For example, when the B vitamin or B vitamin derivative is selected from the group consisting of riboflavin (solubility in water is 1000 mg / 3,000 mL - 15,000 mL depending on crystal structure), folic acid (solubility in water is 0.01 mg / mL), cyanocobalamin (solubility in water is 1000 mg / 80 mL), pantothenic acid (solubility in water is 2110 mg / mL), biotin (solubility in water is 0.22 mg / mL), pyridoxine (solubility in water ranges from 79 mg / mL to 220 mg / mL), and combinations thereof, the B vitamin or B vitamin derivative is present in an amount of from about 1 wt% active to about 5 wt% active based on the total weight of the UV light fusing agent. When the solubility limit of the B vitamins and / or B vitamin derivatives is higher, the B vitamins and / or B vitamin derivatives can be present in an amount of from about 1 wt% active to about 8 wt% active based on the total weight of the fusing agent. For example, when the B vitamin or B vitamin derivative is selected from the group consisting of pyridoxal phosphate hydrate (solubility in water is 5.7 mg / mL), pyridoxal hydrochloride (solubility in water is 11.7 mg / mL), pyridoxine hydrochloride (solubility in water is 200 mg / mL), pyridoxamine (solubility in water is 29 mg / mL), and combinations thereof, the B vitamin or B vitamin derivative can be present in an amount of from about 1 wt% active to about 8 wt% active based on the total weight of the UV light fusing agent.

[0098] Another example of a UV energy absorber is a functionalized benzophenone. Some functionalized benzophenones are absorbent at wavelengths from about 340 nm to 405 nm. The phrase "absorbent at wavelengths from about 340 nm to about 405 nm" means that the functionalized benzophenone exhibits maximum absorbance at wavelengths within the given range and / or has an absorbance of about 0.1 (a transmittance of about 80% or less) at one or more wavelengths within the given range.

[0099] A functionalized benzophenone is a benzophenone substituted with at least one hydrophilic functional group. Functionalization can make the substituted benzophenone more hydrophilic than benzophenone and / or can shift the absorbance of the substituted benzophenone to a desired UV range (340 nm to 405 nm). Thus, a functionalized benzophenone is a benzophenone derivative that includes at least one hydrophilic functional group. In some examples, the functionalized benzophenone is a benzophenone substituted with one hydrophilic functional group. In other examples, the functionalized benzophenone is a benzophenone substituted with two hydrophilic functional groups. In still other examples, the functionalized benzophenone is a benzophenone substituted with three hydrophilic functional groups. In examples where the benzophenone is substituted with multiple functional groups, these groups can be the same or different. Examples of hydrophilic functional groups can optionally be selected from the group consisting of amino, hydroxyl, alkoxy, carboxylic acid, or sulfonic acid groups.

[0100] In an example where at least one hydrophilic functional group is an amino group, the functionalized benzophenone is selected from the group consisting of: 4-aminobenzophenone:

[0101]

[0102] 4,4-dimethylaminobenzophenone:

[0103] and combinations thereof.

[0104] In an example where at least one hydrophilic functional group is a hydroxyl group, the functionalized benzophenone is selected from the group consisting of: 4-hydroxy-benzophenone: 2,4-dihydroxy-benzophenone: 4,4-dihydroxy-benzophenone: 2,4,4'-trihydroxy-benzophenone: 2,4,6-trihydroxy-benzophenone: 2,2',4,4'-tetrahydroxy-benzophenone: 2,3,4-trihydroxy-benzophenone: 2,3,4,4'-tetrahydroxy-benzophenone: and combinations thereof.

[0105] In an example where at least one hydrophilic functional group is an alkoxy group, the functionalized benzophenone is 4,4'-dimethoxybenzophenone:

[0106] In other examples, the functionalized benzophenone can contain different hydrophilic functional groups. In these examples, the functionalized benzophenone is a benzophenone derivative that includes at least two different hydrophilic functional groups.

[0107] In one example, the first hydrophilic functional group among at least two different hydrophilic functional groups is an alkoxy group, and the second hydrophilic functional group among at least two different hydrophilic functional groups is a hydroxyl group. Some examples of these functionalized benzophenones include 2-hydroxy-4-dodecyloxy-benzophenone: 2-hydroxy-4-methoxy-benzophenone: 2,2'-hydroxy-4-methoxy-benzophenone: and combinations thereof.

[0108] In another example, the first hydrophilic functional group among at least two different hydrophilic functional groups can be selected from the group consisting of a hydroxyl group and a carboxylic acid group, and the second hydrophilic functional group among at least two different hydrophilic functional groups is an alkyl group. Some examples of these functionalized benzophenones include 2-hydroxy-4-methyl-benzophenone: and 4'-methylbenzophenone-2-carboxylic acid:

[0109] In yet another example, the first hydrophilic functional group among at least two different hydrophilic functional groups is a hydroxyl group, the second hydrophilic functional group among at least two different hydrophilic functional groups is an alkoxy group, and the third hydrophilic functional group among at least two different hydrophilic functional groups is a sulfonic acid group. An example of such a functionalized benzophenone is 2-hydroxy-4-methoxy-benzophenone-5-sulfonic acid.

[0110] Examples of functionalized benzophenones include 4-hydroxy-benzophenone, 2,4-dihydroxy-benzophenone, 4,4-dihydroxy-benzophenone, 2,4,4'-trihydroxy-benzophenone, 2,4,6-trihydroxy-benzophenone, 2,2’,4,4'-tetrahydroxy-benzophenone, 4,4'-dimethoxybenzophenone, 4-aminobenzophenone, 4-dimethylaminobenzophenone, 2-hydroxy-4-methyl-benzophenone, 4'-methylbenzophenone-2-carboxylic acid, 2-hydroxy-4-dodecyloxy-benzophenone, 2-hydroxy-4-methoxy-benzophenone, 2-hydroxy-4-methoxy-benzophenone-5-sulfonic acid, 2,3,4-trihydroxy-benzophenone, 2,3,4,4'-tetrahydroxy-benzophenone, 2,2'-hydroxy-4-methoxy-benzophenone and combinations thereof.

[0111] Although several examples of functionalized benzophenones have been provided herein, it should be understood that any benzophenone substituted with at least one hydrophilic functional group can be used. These benzophenones can be naturally occurring or synthetic. As an example, benzophenone derivatives having at least one poly(ethylene glycol) (PEG) chain or at least one phosphocholine chain can be synthesized.

[0112] The functionalized benzophenone is at least partially soluble in the aqueous carrier of the melt agent. The phrase "at least partially soluble" means that at least 0.5 wt% of the functionalized benzophenone is capable of dissolving in the aqueous carrier.

[0113] The amount of the functionalized benzophenone present in the UV light melt agent will depend in part on its solubility in the aqueous carrier and its effect on the ejectability of the melt agent. The functionalized benzophenone can be present in an amount of from about 0.01 wt% active to about 10 wt% active, based on the total weight of the melt agent. When the solubility limit of the functionalized benzophenone in the aqueous carrier is low (e.g., soluble less than 5 wt%), the functionalized benzophenone can be present in an amount of from about 0.01 wt% active to about 5 wt% active, based on the total weight of the melt agent. In an example, the functionalized benzophenone can be present in an amount of from about 2 wt% active to about 4 wt% active, based on the total weight of the melt agent.

[0114] Yet another example of a UV energy absorber is a plasmonic metal nanoparticle that i) provides enhanced absorbance at radiation wavelengths of from about 340 nm to about 450 nm and ii) is present in an amount of up to 2 wt% active, based on the total weight of the UV light melt agent.

[0115] In an example, the plasmonic metal nanoparticles are selected from the group consisting of silver nanoparticles, gold nanoparticles, copper nanoparticles, aluminum nanoparticles, and combinations thereof. Exemplary plasmonic metal nanoparticles not only absorb UV in the selected range but also exhibit enhanced absorbance due to localized surface plasmon resonance at the high photon energy end of the near-UV and visible light ranges (range 340 nm - 450 nm). The phrase "absorb radiation at wavelengths of from about 340 nm to about 450 nm" means that the plasmonic metal nanoparticles exhibit maximum absorbance at wavelengths within the given range and / or have an absorbance greater than 1 (about 10% transmittance or less) at one or more wavelengths within the given range.

[0116] The plasmonic metal nanoparticles can have an average particle size of from about 1 nm to about 200 nm. In one example, the plasmonic metal nanoparticles have an average particle size of from about 1 nm to about 100 nm. In another example, the plasmonic metal nanoparticles have an average particle size of from about 1 nm to about 50 nm.

[0117] Yet another example of a suitable UV energy absorber is a fluorescent yellow dye that has a target wavelength for maximum absorbance for a 3D printing system that includes a narrow UV band emission source. The UV light absorber consists of the fluorescent yellow dye and does not contain any other colorants. In particular, any pigments or dyes that absorb other light or any pigments that may precipitate out of solution when included with the fluorescent yellow dye will not be desired.

[0118] The fluorescent yellow dye can be trisodium 8-hydroxy-1,3,6-pyrenetrisulfonate (pyranine): Trisodium 8-hydroxy-1,3,6-pyrenetrisulfonate derivative coumarin: Coumarin derivative naphthalimide:

[0119] Naphthalimide derivatives, disazomethine derivatives: RCH=N-N=CHR or mixtures of these compounds. Some specific examples include Solvent Green 7 (trisodium 8-hydroxy-1,3,6-pyrenetrisulfonate), Acid Yellow 184 (coumarin derivative), Acid Yellow 250 (coumarin derivative), Yellow 101, Basic Yellow 40 (coumarin derivative), Solvent Yellow 43 (naphthalimide derivative), Solvent Yellow 44 (naphthalimide derivative), Solvent Yellow 85 (naphthalimide derivative), Solvent Yellow 145 (coumarin derivative), Solvent Yellow 160:1 (coumarin derivative), and combinations thereof.

[0120] Based on the total weight of the UV light fusing agent, the fluorescent yellow dye can be present in the UV light fusing agent in an amount of about 1 wt% active to about 10 wt% active. In another example, the fluorescent yellow dye can be present in the fusing agent in an amount of about 5 wt% active to about 8 wt% active, or about 5.5 wt% active to about 7.5 wt% active.

[0121] Flux carrier

[0122] Any example of Fusing Agent #1, #2, or #3 (core fusing agent, primer fusing agent, UV light fusing agent) includes a liquid carrier. The fusing agent carrier or "FA carrier" can refer to a liquid in which an energy absorber is dispersed or dissolved to form the corresponding fusing agent. A wide variety of FA carriers can be used in the fusing agent, including aqueous carriers and non-aqueous carriers. In some examples, the FA carrier can consist solely of water or solely of a non-aqueous solvent, i.e., without other components. In other examples, the FA carrier can include other components, depending in part on the applicator to be used to dispense the fusing agent. Examples of other suitable fusing agent components include (a) co-solvents, (a) humectants, (a) surfactants, (a) antimicrobial agents, (a) anti-scaling agents, (a) chelating agents, (a) buffers, (a) pH regulators, (a) preservatives, and / or combinations thereof.

[0123] Water-soluble or water-miscible organic cosolvent classes useful in the flux include fatty alcohols, aromatic alcohols, diols, ethylene glycol ethers, polyethylene glycol ethers, lactams, formamides (substituted and unsubstituted), acetamides (substituted and unsubstituted), ethylene glycol, and long-chain alcohols. Examples of these cosolvents include primary fatty alcohols, secondary fatty alcohols, 1,2-alcohols (e.g., 1,2-ethylene glycol, 1,2-propylene glycol, etc.), 1,3-alcohols (e.g., 1,3-propylene glycol), 1,5-alcohols (e.g., 1,5-pentanediol), 1,6-hexanediol or other diols (e.g., 2-methyl-1,3-propanediol, etc.), ethylene glycol alkyl ethers, propylene glycol, propylene glycol alkyl ethers, higher homologs of polyethylene glycol alkyl ethers (C6-C 12 ), diethylene glycol, triethylene glycol, tripropylene glycol methyl ether, tetraethylene glycol, glycerol, N-alkylcaprolactam, unsubstituted caprolactam, 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-(2-hydroxyethyl)-2-pyrrolidone (also known as N-(2-hydroxyethyl)-2-pyrrolidone (HEP)), etc. Other examples of organic cosolvents include dimethyl sulfoxide (DMSO), isopropyl alcohol, ethanol, pentanol, acetone, etc.

[0124] Based on the total weight of the flux, the (multiple) cosolvent(s) may be present in the flux in a total amount of from about 1 wt% active to about 20 wt% active. In examples, the flux includes from about 2 wt% active to about 15 wt% active, or from about 5 wt% active to about 10 wt% active, of the (multiple) cosolvent(s).

[0125] The FA carrier may also include the (multiple) humectant(s). An example of a suitable humectant is ethoxylated glycerol having the following formula:

[0126] where the sum of a + b + c is in the range of about 5 to about 60, or in other examples, in the range of about 20 to about 30. An example of ethoxylated glycerol is EG-1 (LEG-1, glycerol polyether-26, a + b + c = 26, available from Lipo Chemicals).

[0127] In examples, based on the total weight of the flux, the total amount of the (multiple) humectant(s) present in the flux is from about 3 wt% active to about 10 wt% active.

[0128] The FA carrier may also include (a) surfactant(s). Suitable (a) surfactant(s) include nonionic or anionic surfactants. Some exemplary surfactants include alcohol ethoxylates, alcohol ethoxysulfates, alkynediols, alkyl polyethylene oxides, alkyl phenyl polyethylene oxides, polyethylene oxide block copolymers, alkynyl polyethylene oxides, polyethylene oxide (di)esters, polyethylene oxide amines, protonated polyethylene oxide amines, protonated polyethylene oxide amides, polydimethylsiloxane copolyols, substituted amine oxides, fluorosurfactants, etc. Some specific examples of nonionic surfactants include the following products from Evonik Degussa: SEF (a self-emulsifiable wetting agent based on alkynediol chemistry), 440 or CT-111 (a nonionic ethoxylated low-foaming wetting agent), 420 (a nonionic ethoxylated wetting agent and molecular defoamer), 104E (a nonionic wetting agent and molecular defoamer) and Wet 510 (an organic surfactant). Other specific examples of nonionic surfactants include the following products from Dow Chemical Company: TERGITOL TM TMN-6, TERGITOL TM 15-S-7, TERGITOL TM 15-S-9, TERGITOL TM 15-S-12 (secondary alcohol ethoxylate). Other suitable nonionic surfactants are available from Chemours, including fluorosurfactants, such as FS-35 (a nonionic fluorosurfactant). Some specific examples of anionic surfactants include alkyl diphenyl ether disulfonates (e.g., the DOWFAXTM series, such as 2A1, 3B2, 8390, C6L, C10L, and 30599 from Dow Chemical Company), sodium dioctyl sulfosuccinate (i.e., sodium sulfosuccinate dioctyl ester), sodium dodecyl sulfate (SDS).

[0129] Whether a single surfactant or a combination of multiple surfactants is used, based on the total weight of the fluxing agent, the total amount of (a) surfactant(s) in the fluxing agent can be in the range of about 0.01 wt% active to about 3 wt% active. In an example, based on the total weight of the construction material reactive functional agent, the total amount of (a) surfactant(s) in the fluxing agent can be about 1 wt% active.

[0130] The FA carrier may also include (a) biocide(s). Biocides are also known as germicides and / or fungicides. Examples of suitable biocides include (Ashland Inc.), UCARCIDE TM or KORDEK TM or ROCIMA TM (Dow Chemical Company), (Arch Chemicals) series, B20 and M20 and MBL (a blend of 2-methyl-4-isothiazolin-3-one (MIT), 1,2-benzisothiazolin-3-one (BIT) and bronopol) (Thor Chemicals), AXIDE TM (Planet Chemical), NIPACIDE TM (Clariant), the blend of 5-chloro-2-methyl-4-isothiazolin-3-one (CIT or CMIT) and MIT sold under the trade name KATHON TM (Dow Chemical Company) and combinations thereof.

[0131] In an example, based on the total weight of the flux, the total amount of (a) biocide(s) in the flux is from about 0.01 wt% active to about 0.05 wt% active. In another example, based on the total weight of the flux, the total amount of (a) biocide(s) in the flux is about 0.04 wt% active.

[0132] The FA carrier may also contain (a) scale inhibitor(s) to be ejected using thermal inkjet printing. Scaling refers to the deposition of the dried printing fluid (e.g., the flux) on the heating elements of the thermal inkjet printhead. Inclusion of (a) scale inhibitor(s) helps prevent the build-up of scaling.

[0133] Examples of suitable scale inhibitors include oleth-3-phosphate (available commercially as CRODAFOS TM O3A or CRODAFOS TM N-3A), or dextran 500k. Other suitable examples of scale inhibitors include CRODAFOS TM HCE (a phosphate ester from Croda Int.), O10A (oleth-10-phosphate from Croda Int.) or LFH (an anionic acidic polymer dispersant with an aromatic anchoring group from Clariant Corporation), etc. It should be understood that any combination of the listed anti-scaling agents can be used.

[0134] Based on the total weight of the fluxing agent, the anti-scaling agent can be present in the fluxing agent in an amount of about 0.1 wt% active to about 1.5 wt% active. In the example, based on the total weight of the fluxing agent, the anti-scaling agent is present in an amount of about 0.5 wt% active.

[0135] A chelating agent (or complexing agent) can be included in the FA carrier of the fluxing agent to eliminate the harmful effects of heavy metal impurities. In the example, the chelating agent is selected from the group consisting of: trisodium methylglycinediacetate; disodium 4,5-dihydroxy-1,3-benzenedisulfonate monohydrate; ethylenediaminetetraacetic acid (EDTA); potassium hexamethylenediaminetetra(methylenephosphonic acid); and combinations thereof. Trisodium methylglycinediacetate (Na3MGDA) can be purchased commercially from BASF Corp., and disodium 4,5-dihydroxy-1,3-benzenedisulfonate monohydrate can be purchased commercially as TIRON TM monohydrate. Potassium hexamethylenediaminetetra(methylenephosphonic acid) can be purchased commercially as 2054 from Italmatch Chemicals.

[0136] Whether a single chelating agent or a combination of multiple chelating agents is used, based on the total weight of the fluxing agent, the total amount of the chelating agent(s) in the fluxing agent can be in the range of greater than 0 wt% active to about 0.5 wt% active. In the example, based on the total weight of the fluxing agent, the chelating agent is present in an amount of about 0.05 wt% active to about 0.2 wt% active. In another example, based on the total weight of the fluxing agent, the chelating agent(s) is present in the fluxing agent in an amount of about 0.05 wt% active.

[0137] Some examples of the fluxing agent include buffering agents. The buffering agent can be TRIS (tris(hydroxymethyl)aminomethane or )、TRIS or Hydrochloride, bis - tripropane, TES (2 - [(2 - hydroxy - 1,1 - bis(hydroxymethyl)ethyl)amino]ethanesulfonic acid), MES (2 - ethanesulfonic acid), MOPS (3 - (N - morpholino)propanesulfonic acid), HEPES (4 - (2 - hydroxyethyl)-1 - piperazineethanesulfonic acid), DIPSO (3 - (N,N - bis[2 - hydroxyethyl]amino)-2 - hydroxypropanesulfonic acid), trimethylglycine (N - [tris(hydroxymethyl)methyl]glycine), HEPPSO (β - hydroxy - 4 - (2 - hydroxyethyl)-1 - piperazinepropanesulfonic acid monohydrate), POPSO (piperazine - 1,4 - bis(2 - hydroxypropanesulfonic acid) dihydrate), EPPS (4 - (2 - hydroxyethyl)-1 - piperazinepropanesulfonic acid, 4 - (2 - hydroxyethyl)piperazine - 1 - propanesulfonic acid), TEA (triethanolamine buffer solution), Gly - Gly (glycylglycine), N,N - dihydroxyethylglycine (N,N - bis(2 - hydroxyethyl)glycine), HEPBS (N - (2 - hydroxyethyl)piperazine - N’-(4 - butanesulfonic acid)), TAPS ([tris(hydroxymethyl)methylamino]propanesulfonic acid), AMPD (2 - amino - 2 - methyl - 1,3 - propanediol), TABS (N - tris(hydroxymethyl)methyl - 4 - aminobutanesulfonic acid), etc.

[0138] In an example, based on the total weight of the fluxing agent, the total amount of the (multiple) buffering agents in the fluxing agent is from about 0.01 wt% to about 3 wt%.

[0139] Some examples of the fluxing agent include pH regulators. Suitable pH regulators can include amino acids or sodium bicarbonate. An example of a suitable amino acid pH regulator is taurine. In an example, based on the total weight of the fluxing agent, the total amount of the (multiple) pH regulators in the fluxing agent is from about 0.01 wt% to about 3 wt%.

[0140] Some examples of the fluxing agent include preservatives. Preservatives may be particularly suitable when vitamin B or vitamin B derivatives are used as energy absorbers. Examples of suitable preservatives include 2 - phenoxyethanol, sodium benzoate, and parabens. In an example, based on the total weight of the UV light fluxing agent, the total amount of the (multiple) preservatives in the fluxing agent is from about 0.1 wt% to about 3 wt%.

[0141] Some examples of the fusing agent, particularly a UV light fusing agent, also include bases. In some examples, B vitamins or B vitamin derivatives are more soluble at neutral or basic pH. For example, folic acid is more soluble in an aqueous carrier with a pH greater than 5. Thus, it may be desirable to add a base (such as potassium hydroxide, sodium hydroxide, or tetramethylammonium hydroxide) until the desired pH is obtained. In an example, based on the total weight of the fusing agent, the total amount of base in the fusing agent is about 0.5 wt% to about 5 wt%. In other examples, based on the total weight of the fusing agent, the amount of base can be in the range of about 0.75 wt% to about 2.5 wt%.

[0142] The balance of the fusing agent is water (such as deionized water, purified water, etc.). The amount of water can vary depending on the amounts of other components in the fusing agent. In one example, the fusing agent can be ejected through a thermal inkjet printhead and contains about 50 wt% to about 90 wt% water.

[0143] Fusing agent #4

[0144] Yet another example of a fusing agent (“fusing agent #4”) is referred to as a color fusing agent because it contains a colored visible light absorber (which exhibits absorption at least at wavelengths in the visible light region). The visible wavelengths of light can be in the range of 400 nm to 780 nm. In an example, the visible wavelength of light can be approximately 455 nm.

[0145] The color fusing agent includes a first solvent that provides a polymer plasticizer, a second solvent that is miscible with water, and a colored visible light absorber that absorbs visible wavelength light.

[0146] The first solvent can be a plasticizer and / or can have plasticizing properties when interacting with the build material composition of Embodiment 1 or the build material of Embodiment 2. For example, the first solvent can interact with thermoplastic polyurethane to lower the melting temperature of the build material composition. The first solvent can be an organic solvent such as benzyl alcohol or diethylene glycol butyl ether (DEGBE).

[0147] The first solvent can be present in the color fusing agent in an amount in the range of about 10 wt% active to about 40 wt% active.

[0148] The second solvent can be a water-miscible solvent that is compatible with the colored visible light absorber. The second solvent can help keep the colored visible light absorber dissolved in the water of the color fusing agent and can help provide stability and prevent the colored visible light absorber from aggregating over time. In an example, the second solvent can include at least one of diethylene glycol (DEG) butyl ether, 1,2 - hexanediol, hydroxyethyl - 2 - pyrrolidone (HE2P), glycerol, propylene glycol and its oligomers, ethylene glycol and its oligomers, or 1,5 - pentanediol.

[0149] The second solvent may be present in the colored flux in an amount ranging from about 30 wt% active to about 60 wt% active.

[0150] In an example, the colored visible light absorber can be any colored light absorber capable of absorbing light in the visible wavelength range. For example, the colored visible light absorber can absorb light with wavelengths between 400 nm and 780 nm. In a specific example, the colored visible light absorber can be a dye that absorbs light at approximately 455 nm. Examples of colored visible light absorbers that can absorb light with a wavelength approximately 455 nm include Acid Yellow 23 (AY-23), Acid Yellow 1, trisodium 8-hydroxy-1,3,6-pyrenetrisulfonate, and Direct Black 168 (DB-168).

[0151] The colored visible light absorber may be present in the colored flux in an amount less than 3 wt% active. As an example, the colored visible light absorber can be added in an amount as low as less than 0.05 wt% active of the total weight of the colored flux. As another example, the colored visible light absorber can be added in an amount of 0.75 wt% active. In yet another example, an amount of the colored visible light absorber in the range of about 0.1 wt% active to 3 wt% active can be added based on the total weight of the colored flux.

[0152] By using a relatively low amount of the colored visible light absorber, different colored fluxes can be formulated using a small amount of colored dye that does not affect the melting properties of the colored flux. Thus, some examples of the colored flux also include additional colored dyes that do not absorb light at the same wavelength as the colored visible light absorber. The additional colored dyes can be used to formulate different colored fluxes without affecting the overall melting behavior of the different colored fluxes. Examples of the colored dyes can include C854, AY17, Acid Red (AR) 52, AR 289, Reactive Red 180 (RR 180), Direct Blue (DB) 199, Pigment Blue (PB) 15:3, Pigment Red (PR) 122, Pigment Yellow (PY) 155, PY74, and cesium tungsten oxide.

[0153] Based on the total weight of the colored flux, the amount of the additional dye is in the range of about 0.10 wt% active to about 3 wt% active. The amount of the additional dye can be varied to achieve the desired color. For example, when a dark portion (e.g., dark magenta, dark cyan, etc.) is desired, more additional dye can be added, while when a light portion (e.g., light magenta, light cyan, etc.) is desired, less additional dye can be added.

[0154] The colored flux may also include any other suitable flux components, such as (a) humectant(s), (a) surfactant(s), (an) antimicrobial agent(s), (an) anti-scaling agent(s), (a) buffer(s), (a) pH regulator(s), and / or combinations thereof. Any one of these components may be added in the amounts described herein for the flux carrier (except that the total amount is relative to the colored flux). In one example, the colored flux also includes a surfactant in an amount ranging from about 0.5 wt% active to about 1 wt% active. The surfactant may include secondary alcohol ethoxylates, such as TERGITOL TM 15-S-9, or other water-soluble nonionic surfactants described herein.

[0155] Refining agent

[0156] A 3D printing method involving selectively applying a flux to pattern a layer of a build material composition may also involve selectively applying a refinisher. The refinisher does not include an energy absorber and may be applied to (a) portion(s) of the build material composition outside of the area based on the 3D digital model used to form the 3D printed article. The (a) portion(s) of the build material composition exposed to the refinisher may experience a cooling effect, and thus the refinisher helps prevent the (a) portion(s) from coalescing. The refinisher may also be applied in the same (a) portion(s) as the flux. In these examples, the cooling effect of the refinisher can be used to regulate the degree of melting in the (a) portion(s).

[0157] The refinisher may include a surfactant, a co-solvent, and balance water. In some examples, the refinisher consists of these components and does not contain other components. In some other examples, the refinisher may also contain a colorant. In still some other examples, the refinisher consists of a colorant, a surfactant, a co-solvent, and balance water and does not contain other components. In yet some other examples, the refinisher may also contain additional components, such as (a) anti-scaling agent(s), (an) antimicrobial agent(s), and / or (a) chelating agent(s) (each component was described above with reference to the flux).

[0158] The (a) surfactant(s) that can be used in the refinisher includes any surfactant listed herein with reference to the flux. The total amount of the (a) surfactant(s) in the refinisher may be in the range of about 0.10 wt% active to about 5.00 wt% active relative to the total weight of the refinisher.

[0159] The (a) co-solvent(s) that can be used in the refinisher includes any co-solvent listed above with reference to the flux. The total amount of the (a) co-solvent(s) in the refinisher may be in the range of about 1 wt% active to about 65 wt% active relative to the total weight of the refinisher.

[0160] In some examples, the finishing agent does not include a colorant. In these examples, the finishing agent may be colorless. As used herein, the term "colorless" means that the finishing agent is non-colored and does not contain a colorant. A colorless finishing agent can be used with any of the fusing agents disclosed herein.

[0161] In other examples, the finishing agent does contain a colorant. When applying the finishing agent to the edges of a colored 3D printed article (e.g., an article formed using a core fusing agent), it may be desirable to add color to the finishing agent. The color in the finishing agent may be desirable when used at the edges of the article because some colorants may become embedded in the build material composition that melts / coalesces at the edges. Thus, in some examples, the dye in the finishing agent can be selected such that its color matches the color of the energy absorber in the fusing agent. As an example, the dye can be any azo dye having sodium or (multiple) potassium counterions, or any diazo (i.e., bisazo) dye having sodium or (multiple) potassium counterions, where the color of the azo or bisazo dye matches the color of the fusing agent.

[0162] When the finishing agent contains a colorant and is to be used with a core fusing agent, the colorant can be a dye of any color that has substantially no absorbance in the range of 650 nm to 2500 nm. "Substantially no absorbance" means that the dye does not absorb radiation having wavelengths in the range of 650 nm to 2500 nm, or the dye absorbs less than 10% of the radiation having wavelengths in the range of 650 nm to 2500 nm. The dye can also be capable of absorbing radiation having a wavelength of 650 nm or less. Thus, the dye absorbs at least some wavelengths within the visible spectrum but little or no radiation within the near-infrared spectrum. This is in contrast to the energy absorber in the core fusing agent, which absorbs wavelengths within the near-infrared spectrum. Thus, the colorant in the finishing agent will generally not absorb the fusing radiation and thus will not initiate melting and fusing (coalescence) of the build material composition in contact therewith when the build material layer is exposed to energy.

[0163] In an example, the dye is a black dye. Some examples of black dyes include azo dyes having sodium or potassium counterions and diazo (i.e., bisazo) dyes having sodium or (multiple) potassium counterions. Examples of azo and bisazo dyes can include tetrasodium (6Z)-4-acetamido-5-oxo-6-[[7-sulphonato-4-(4-sulphonatophenyl)azo-1-naphthyl]hydrazono]naphthalene-1,7-disulphonate, the chemical structure of which is: (Commercially available as Food Black 1); tetrasodium 6-amino-4-hydroxy-3-[[7-sulphonato-4-[(4-sulphonatophenyl)azo]-1-naphthyl]azo]naphthalene-2,7-disulphonate, the chemical structure of which is: (Commercially available as Food Black 2); tetrasodium (6E)-4-amino-5-oxo-3-[[4-(2-sulfooxyethylsulfonyl)phenyl]diazenyl]-6-[[4-(2-sulfooxyethylsulfonyl)phenyl]hydrazinyl]naphthalene-2,7-disulfonate, the chemical structure of which is: (Commercially available as Reactive Black 31); tetrasodium (6E)-4-amino-5-oxo-3-[[4-(2-sulfooxyethylsulfonyl)phenyl]diazenyl]-6-[[4-(2-sulfooxyethylsulfonyl)phenyl]hydrazinyl]naphthalene-2,7-disulfonate, the chemical structure of which is: And combinations thereof. Some other commercially available examples of dyes for the fining agent include: multi-purpose black azo dye-based liquids such as Fast Black 1 (available from Fujifilm Holdings); and black azo dye-based liquids with enhanced water color fastness such as Fast Black 2 (available from Fujifilm Holdings).

[0164] In some cases, in addition to the black dye, the colorant in the fining agent may also include another dye. In the example, the other dye may be a cyan dye used in combination with any of the dyes disclosed herein. The other dye may also be substantially free of absorbance above 650 nm. The other dye may be any colored dye that helps to improve the hue and color uniformity of the final 3D printed object.

[0165] Some examples of other dyes include salts such as sodium salts, ammonium salts or potassium salts. Some specific examples include ethyl-[4-[[4-[ethyl-[(3-sulfophenyl)methyl]amino]phenyl]-(2-sulfophenyl)ethylidene]-1-cyclohex-2,5-dienylidene]-[(3-sulfophenyl)methyl]ammonium salt, the chemical structure of which is: (Commercially available as Acid Blue 9, where the counterion may alternatively be a sodium counterion or a potassium counterion); sodium 4-[(E)-{4-[benzyl(ethyl)amino]phenyl}{(4E)-4-[benzyl(ethyl)imino]cyclohex-2,5-dien-1-ylidene}methyl]benzene-1,3-disulfonate, the chemical structure of which is: (Commercially available as Acid Blue 7); and phthalocyanine, the chemical structure of which is: (Commercially available as Direct Blue 199); and combinations thereof.

[0166] In an example of a refiner, the dye may be present in an amount of about 1 wt % active to about 3 wt % active, based on the total weight of the refiner. In another example of a refiner comprising a combination of dyes, one dye (e.g., a black dye) is present in an amount of about 1.50 wt % active to about 1.75 wt % active, based on the total weight of the refiner, and another dye (e.g., a cyan dye) is present in an amount of about 0.25 wt % active to about 0.50 wt % active, based on the total weight of the refiner.

[0167] The balance of the refiner is water. Therefore, the amount of water may vary depending on the amounts of the other components included.

[0168] Colorant

[0169] The 3D printing method comprising selectively applying a fusing agent to pattern a layer of a build material composition may also comprise selectively applying a colorant. The colorant may be used to impart color to the 3D printed article.

[0170] In these examples, the colorant is separate from the flux. A colorant separate from the flux may be desirable because the two agents may be applied separately, allowing control over where the color is added. The colorant may be applied during printing (e.g., on a build material composition with a flux) or after printing (e.g., on a 3D printed article) to impart a colored appearance to the 3D printed article.

[0171] The colorant may include a colorant, a co-solvent, and a balance of water. In some examples, the colorant consists of these components and contains no other components. In other examples, the colorant may also include additional components that aid in the dispersibility of the colorant and / or the jetting properties of the ink. Some examples of other colorant components include (multiple) dispersants (e.g., water-soluble acrylic polymers (e.g., available from Lubrizol Corporation) K7028), water-soluble styrene-acrylic acid copolymer / resin (e.g., available from BASF 296, 671, 678, 680, 683, 690, etc.), high molecular weight block copolymers with pigment-affinic groups (e.g., available from BYK Additives and Instruments -190) or water-soluble styrene-maleic anhydride copolymer / resin), humectant(s), surfactant(s), anti-fouling agent(s) and / or antimicrobial agent(s) (examples of which are described herein with reference to the flux).

[0172] The colorant can be a black reagent, a cyan reagent, a magenta reagent, or a yellow reagent. Accordingly, the colorant can be a black colorant, a cyan colorant, a magenta colorant, a yellow colorant, or a combination of colorants that together achieve black, cyan, magenta, or yellow. Although some examples have been provided, it should be understood that other colored inks can also be used.

[0173] The colorant of the colorant can be any pigment or dye. When the colorant is a separate reagent, the pigment or dye will impart color and is not intended to replace the energy absorber in the melt agent. Accordingly, the colorant can act as an energy absorber or as part of an energy absorber, or it can provide no energy absorption.

[0174] Examples of pigment-based colored inks can include about 1 wt% to about 10 wt% of (one or more) pigments, about 10 wt% to about 30 wt% of (one or more) co-solvents, about 1 wt% to about 10 wt% of (one or more) dispersants, 0.01 wt% to about 1 wt% of (one or more) anti-scaling agents, about 0.05 wt% to about 0.1 wt% of (one or more) anti-microbial agents, and the balance water. Examples of dye-based colored inks can include about 1 wt% to about 7 wt% of (one or more) dyes, about 10 wt% to about 30 wt% of (one or more) co-solvents, about 1 wt% to about 7 wt% of (one or more) dispersants, about 0.05 wt% to about 0.1 wt% of (one or more) anti-microbial agents, 0.05 wt% to about 0.1 wt% of (one or more) chelating agents, about 0.005 wt% to about 0.2 wt% of (one or more) buffering agents, and the balance water.

[0175] 3D printing kit

[0176] The build material composition can be part of a 3D printing kit together with one or more of the above melt agents. In one example, the 3D printing kit is a single melt agent kit that includes the build material composition and a single melt agent (such as a core melt agent or a primer melt agent or a UV light melt agent or a color melt agent). In another example, the 3D printing kit is a multi-melt agent kit that includes the build material composition and two or more melt agents (such as a core melt agent and a primer melt agent).

[0177] Any example of a 3D printing kit can also be a multi-fluid kit that includes the build material composition (which is a dry or solid component), one or more melt agents, and the above-mentioned refiners and / or colorants.

[0178] It should be understood that the (multiple) fluid and build material compositions of the 3D printing kit can be maintained separately until they are used together in the 3D printing method described below. The (multiple) fluid and / or build material compositions can be each contained in one or more containers before and during printing, but can be combined together during printing. The containers can be any type of vessel (e.g., reservoir), cartridge, or receptacle made of any material.

[0179] 3D printing method

[0180] The following refers to Figure 1 A 3D printing method using a build material composition is described. The 3D printing method utilizes a 3D printing system 100. The printing system 100 includes a build area platform 102 having a build surface 104 on which a 3D printed article is built, formed, or created. The build surface 104 defines the X-Y plane for building the 3D printed article. The build area platform 102 is movable in a direction along the Z-axis, as shown by the arrow A in Figure 1 In addition, based on a 3D digital model, the build area platform 102 is programmable to move along the Z-axis, as shown in the example depicted in Figure 1 To move in the downward direction so that the build material composition 10 can be delivered to the build surface 104 or a previously formed layer on the build surface 104. It should be noted that once the 3D printed article has been built, the build area platform 102 can also move in the opposite direction along the Z-axis to return the build area platform 102 to its initial position.

[0181] The 3D printing system 100 also includes a build material supply source 106 for containing the build material composition 10. The build material supply source 106 can be a container, bed, or other surface and is configured to position the build material composition 10 between the build material dispenser 108 and the build area platform 102 during printing. In an example, the build material supply source 106 includes a heater so that the build material composition 10 can be heated to a suitable supply temperature, such as from about 25°C to about 135°C. The supply temperature can depend in part on the build material composition 10 and / or the 3D printing system 100. Thus, the provided range is an example, and higher or lower temperatures can be used as long as the supply temperature is below the lowest temperature in the melting range of the thermoplastic polyurethane particles in the build material composition 10.

[0182] The 3D printing system 100 also includes a build material dispenser 108 coupled to the build material supply source 106. The dispenser 108 is movable in two directions along the Y-axis above the build material supply source 106 and through the build area platform 102 (as shown in Figure 1as shown by arrow B in [Fig.], for spreading the build material composition 10 to form a build material layer 16. The dispenser 108 can be a blade (e.g., a squeegee), a roller, a combination of a roller and a blade, and / or any other device capable of spreading the build material composition 10 on the build area platform 102. In one example, the dispenser 108 is a counter-rotating roller.

[0183] The 3D printing system 100 also includes a heat source adapted to expose the build material composition 10 deposited on the build area platform 102 to heating. Examples of heat sources include a thermal heat source (e.g., a heater (not shown) integrated into the build area platform 102 which may include sidewalls)) or a radiation source 110.

[0184] The 3D printing system 100 also includes an applicator 112 coupled to a fluid supply source (not shown) and adapted to dispense a fluid, such as a fusing agent 18, onto (a) selected portion(s) of the build material composition 10. The fusing agent 18 is dispensed onto (a) selected portion(s) of the build material composition 10 according to a 3D digital model. In an example, the applicator 112 includes a thermal inkjet printhead, a piezoelectric printhead, a continuous inkjet printhead, etc., and the selective application of the fusing agent 18 can be accomplished by thermal inkjet printing, piezoelectric inkjet printing, continuous inkjet printing, etc. Other devices capable of using inkjet technology to eject a fluid are also contemplated for the applicator 112.

[0185] In an example, the 3D printing system 100 can include at least one additional applicator 112', and another fluid 22, such as a refining agent or a coloring agent, can be dispensed from the at least one additional applicator 112'. The at least one additional applicator 112' includes any of the above-mentioned inkjet printheads and corresponding inkjet technologies. Additionally, the applicators 112, 112' can be separate applicators, or they can also be a single applicator having several separate cartridges for dispensing the respective fluids 18, 22. When more than two fluids are required, additional applicators can also be used.

[0186] The printing system 100 also includes a controller (not shown). The controller is configured to access data stored in a data repository related to the 3D article to be built. In an example, the data includes a 3D digital model of the 3D article to be built, and additional data such as the number of build material layers 16 to be formed, the locations where the fluid is to be deposited on one or more build material layers 16, etc.

[0187] Before performing the 3D printing method of Embodiment 1, the build material composition 10 can be first prepared by combining thermoplastic polyurethane particles 12 with a thermally conductive filler 14 to form a dry blend. As described above, both the thermoplastic polyurethane particles 12 and the thermally conductive filler 14 can be provided in powder form. In an example, the combining can involve dry blending the powders together to form a dry blend. The combining step can be accomplished by mixing the powders together in a mixer or blender suitable for combining dry components. The amount of mixing time can be any amount of time suitable for forming a homogeneous mixture of the thermoplastic polyurethane 12 and the filler 14.

[0188] Details of the 3D printing method for Embodiment 1 will now be described. The 3D printing method includes a step of applying the build material composition 10 to form a build material layer 16, wherein the build material composition 10 includes thermoplastic polyurethane particles 12 present in an amount of about 90 wt% to about 99 wt% and a thermally conductive filler 14 present in an amount of about 1 wt% to about 10 wt%. The thermally conductive filler 14 is selected from the group consisting of cubic boron nitride and diamond-like carbon. The amounts of the thermoplastic polyurethane particles 12 and the thermally conductive filler 14 are based on the total weight of the build material composition 10.

[0189] The step of applying the build material composition 10 includes ejecting a predetermined amount of the build material composition 10 from a supply source 106 via a build material dispenser 108 and pushing it onto the surface 104 of a build area platform 102. In an example, the build area platform 102 is programmed (by a controller) to advance a sufficient distance in the direction of arrow A such that the build material dispenser 108 can push the build material composition 10 onto the build area platform 102. For example, when a 3D printed article has been built and thus the 3D printing method is complete, the build area platform 102 can also be programmed to return to its original position.

[0190] The method further includes a step of spreading the build material composition 10. Spreading is effected by moving the dispenser 108 in the Y direction in the X - Y plane to form a generally uniform layer 16 of the build material composition 10. Thereafter, the dispenser 108 returns to a position adjacent to the supply source 106. In some cases, the supply source 106 or a portion of the supply source 106 is translated with the dispenser 108 such that the build material composition 10 is continuously delivered to the build area platform 102, rather than being supplied from a single position at the side of the printing system 100 as Figure 1 shown.

[0191] In an example, a supply source 106 supplies a build material composition 10 into a location such that the build material composition 10 is ready to be spread onto a build area platform 102. A build material dispenser 108 spreads the supplied build material composition 10 onto the build area platform 102. A controller processes "control build material supply source" data and, in response, controls the supply source 106 to appropriately position particles 12, 14 of the build material composition 10. The controller also processes "control spreader data" and, in response, controls the dispenser 108 to spread the build material composition 10 onto the build area platform 102 to form a build material layer 16. In Figure 1 a build material layer 16 has been formed.

[0192] The formed build material layer 16 has a generally uniform thickness on the build area platform 102. In an example, the build material layer 16 has a thickness of from about 50 μm to about 120 μm. In another example, the thickness of the build material layer 16 is from about 30 μm to about 200 μm. It should be understood that thinner or thicker layers may also be used. In the minimum layer thickness for more refined part definitions, the layer thickness can be about 2x (i.e., 2 times) the average particle size (e.g., diameter) of the thermoplastic polyurethane particles. In some examples, the layer thickness can be about 1.2 times the average diameter of the thermoplastic polyurethane particles in the build material composition 10.

[0193] After the build material composition 10 has been applied and spread and before further processing, the method includes a step of preheating the build material layer 16. The preheating step is carried out to heat the build material layer 16 and is carried out before the step of applying a fluid (such as a fusing agent 18) described below. In an example, the preheating temperature can be lower than the lowest melting temperature of the melting range of the thermoplastic polyurethane particles 12 in the build material composition 10. As an example, the heating temperature can be in the range of about 10 °C to about 100 °C lower than the lowest melting temperature of the thermoplastic polyurethane particles 12. In a particular example, the preheating temperature is in the range of about 45 °C to about 135 °C.

[0194] After the build material layer 16 has been formed and in some cases preheated, the method further includes a step of selectively applying a fusing agent 18 including an energy absorber onto at least a portion of the build material layer 16 based on a 3D digital model to produce a patterned portion 20. As described above, the fusing agent 18 is dispensed from an applicator 112. In an example, the controller processes data for a corresponding layer of the 3D object model and, in response, controls the applicator 112 to selectively deposit the fusing agent 18 onto (a) predetermined portion(s) 20 of the build material layer 16. The predetermined portion of the build material layer 18 patterned with the fusing agent 18 is referred to herein as (a) patterned portion(s) 20.

[0195] Any one of a core flux, a primer flux, a UV light flux, or a color flux can be used as the flux 18. When it is desired to form a white, colored, or slightly colored layer of the 3D article, a primer flux or a UV light flux can be used to pattern the layer 16 of the build material composition 10. The primer flux or the UV light flux is transparent or slightly colored (depending on the energy absorber used), and thus the final layer of the 3D printed article may appear white, light-colored (e.g., yellow), or the color of the build material composition 10. When it is desired to form a layer having a specific color (e.g., magenta, cyan, blue, etc.), a color flux can be used. When it is desired to form a darker color or a black layer, a core flux can be used. The core flux is dark or black, and thus the final layer of the 3D printed article may appear gray, black, or another dark color. Two or more fluxes can also be used to pattern different portions of a single build material layer. Additionally, color can be added by using colorants (as described below).

[0196] The amount of the flux 18 applied to the build material composition 10 in the patterned portion 20 should be sufficient to absorb and convert enough electromagnetic radiation so that the build material composition 10 in the patterned portion 20 will coalesce / melt. The amount of the flux 18 applied depends at least in part on the energy absorber used, the energy absorber loading in the flux 18, and the components of the build material composition 10 (particularly the amount of the thermally conductive filler 14 in the build material composition 10). In particular, the concentration of the energy absorber in the flux 18 can be considered. This concentration can be used to determine how much of the flux 18 to apply to achieve a weight ratio of the flux 18 to the build material composition 10, thereby achieving acceptable layer-by-layer melting. Thus, if the flux 18 (10 wt%) is applied to the build material composition 10 (90 wt%) at a weight ratio of about 1:9, the weight ratio of the energy absorber to the build material composition 10 (as applied) can be from about 1:9000 to about 1:22.5. If more (up to 20 wt%) or less (down to 5 wt%) of the flux 18 is applied to the build material composition 10, these ratios can be adjusted accordingly. That is, in some more specific examples, the weight ratio of the energy absorber to the build material composition 10 (as applied) can be, for example, from about 1:1000 to about 1:80, from about 1:800 to about 1:100, or from about 1:500 to about 1:150.

[0197] The selective application of the fusing agent 18 can be accomplished in a single print pass or in multiple print passes. In some examples, the fusing agent 18 is selectively applied during a single print pass. In some other examples, during multiple print passes, such as during 2 to 4 passes, the fusing agent 18 is selectively applied. It may be desirable to apply the fusing agent 18 in multiple print passes to increase, for example, the amount of energy absorber applied to the build material composition 10, thereby avoiding liquid splashing, avoiding displacement of the build material composition 10, etc.

[0198] In an example, another fluid 22, such as a refining agent or a colorant, can be dispensed from an additional applicator 112'. The another fluid 22 can be selectively applied in a single print pass or in multiple print passes.

[0199] In Figure 1 the example shown, the another fluid 22 is a refining agent that is selectively applied to the (multiple) portions 36 of the layer 16 that are outside of the (multiple) patterned portions 20. These (multiple) portions 36 are not patterned with the fusing agent 18 and thus do not become part of the final 3D printed article layer 24. The thermal energy generated during radiation exposure can propagate into the (multiple) surrounding portions 36 where the fusing agent 18 is not applied. When the refining agent is applied to the (multiple) non-patterned build material portions 36, the propagation of the thermal energy can be inhibited and thus the coalescence of the (multiple) non-patterned build material portions 36 can be prevented. Although Figure 1 not shown in, the refining agent can also or alternatively be applied to the (multiple) patterned portions 20 together with the fusing agent 18 to reduce the degree of melting in the (multiple) patterned portions 20. In these examples, the amount of the refining agent (the another fluid 22) applied should be low enough so that melting is not completely inhibited.

[0200] After the reagent 18 and / or the fluid 22 have been selectively applied in the (multiple) specific portions 20, 36 of the build material layer 16, the entire layer 16 of the build material composition 10 is exposed to electromagnetic radiation (shown as Figure 1 EMR in).

[0201] Electromagnetic radiation is emitted from the radiation source 110. The length of time or energy exposure during which the electromagnetic radiation is applied can depend on, for example, one or more of the following: the characteristics of the radiation source 110; the characteristics of the build material composition 10; and / or the characteristics of the fusing agent 18. For example, the presence of the filler 14 in the build material composition 10 increases the thermal conductivity of the build material composition 10, and thus enables the build material composition 10 to heat up and melt faster than when the filler 14 is absent. Accordingly, the presence of the filler 14 can reduce the time required for electromagnetic radiation exposure. In an example, electromagnetic radiation exposure is carried out for a time period of from about 0.5 seconds to about 4 seconds. Additionally, for example, when compared to the energy levels used with a thermoplastic polyurethane build material composition that does not contain the filler 14, electromagnetic radiation exposure can be carried out at a reduced energy level due to the presence of the filler 14.

[0202] Electromagnetic radiation exposure can be accomplished in a single radiation event or in multiple radiation events. As used herein, the term "radiation event" refers to a period of electromagnetic radiation exposure from the radiation source 110. In an example, a radiation event can occur when the movable radiation source 110 passes over the build material layer 16 (similar to a printing pass). In an example, the number of radiation events ranges from 1 to 8, and can thus be carried out as a single radiation event or multiple events. It may be desirable to expose the build material composition 10 to electromagnetic radiation in multiple radiation events to counteract the cooling effect that the amount of fusing agent 18 (alone or in combination with another fluid 22) applied to the build material layer 16 may impart. Additionally, it may be desirable to expose the build material composition 10 to electromagnetic radiation in multiple radiation events to sufficiently raise the temperature of the build material composition 10 in the (multiple) patterned portions 20 without overheating the build material composition 10 in the non-(multiple) patterned portions 36.

[0203] The fusing agent 18 enhances the absorption of radiation, converts the absorbed radiation into heat energy, and facilitates the transfer of heat energy to the build material composition 10 with which it is in contact. The enhanced thermal conductivity of the build material composition 10 enables the (multiple) patterned portions 20 to reach the melting range of the thermoplastic polyurethane particles 12 more efficiently than in the absence of the filler 14. Accordingly, the combination of the filler 14 and the fusing agent 18 sufficiently raises the temperature of the build material composition 10 in the patterned portions 20 to a temperature above the minimum melting temperature of the thermoplastic polyurethane particles, thereby allowing coalescence / fusion (e.g., thermal merging, melting, bonding, etc.) of the build material composition 10 to occur. The application of electromagnetic radiation forms the layer 24 of the 3D printed article.

[0204] In some examples, the electromagnetic radiation has a wavelength of 100 nm to 400 nm, 400 nm to 4000 nm, or 800 nm to 1400 nm, or 800 nm to 1200 nm. The radiation used depends on the fusing agent 18 employed. Radiation having a wavelength within an appropriate range can be absorbed by the fusing agent 18 and can heat the build material composition 10 in contact therewith and can be not absorbed by the unpatterned build material composition 10 (e.g., in the (multiple) portions 36).

[0205] After a layer 24 of the 3D printed article has been formed, (multiple) additional layers can be formed thereon to create an example of a 3D printed article. To form the next layer, an additional build material composition 10 is applied onto the layer 24 of the 3D printed article. Then, based on data obtained from the 3D digital model, the fusing agent 18 is selectively applied to at least a portion of the additional build material composition 10. After applying the fusing agent 18 (alone or in combination with another fluid 22), the entire layer of the additional build material composition 10 is exposed to electromagnetic radiation in the manner described above. The application of the additional build material composition 10, the selective application of the fusing agent 18, and the electromagnetic radiation exposure can be repeated for a predetermined number of cycles to form the final 3D printed article according to the 3D digital model. Details of the 3D printed article are described below.

[0206] The 3D printed article produced using the method of Embodiment 1 may appear darker in color when using a core fusing agent, or may appear white or the color of the build material composition 10 when using a primer or UV fusing agent, or may have a slight color when using a UV fusing agent, or may be colored when using a colored fusing agent. For a 3D printed article with a lighter color, color can be added during 3D printing or using a separate colorant after the 3D printed article is produced.

[0207] In one example, the method further includes selectively applying a colorant to the (multiple) patterned portions 20 based on the 3D object model. In this example, the colorant is applied to the build material composition 10 together with the fusing agent 18. In this example, the colorant of the colorant is embedded in the entire coalesced / fused build material composition 10 of the 3D article layer 24. To introduce color, it may be desirable to introduce the colorant into the patterned portions 20 that define the edge boundaries of the 3D printed article being formed.

[0208] In yet another example, the method further includes selectively applying a colorant to the 3D printed article layer 24 (after coalescence has occurred) based on the 3D object model. In this example, the colorant is applied to the outer surface of the 3D printed article layer 24.

[0209] In the examples disclosed herein, the 3D printed article can be printed in any orientation. For example, the 3D printed article can be printed from bottom to top, from top to bottom, from the side, at an angle, or in any other orientation. The orientation of the 3D object can also be formed in any orientation relative to the layering of the build material composition 10. For example, the 3D printed article can be formed in an inverted orientation or on its side relative to the layering of the build material composition 10. For example, the build orientation within each layer 16 can be preselected or even selected by the user during printing.

[0210] Embodiment 2

[0211] In Embodiment 2, the thermally conductive filler is incorporated into the thermally conductive agent selectively applied to the build material layer, rather than being incorporated into the build material composition 10 as described in Embodiment 1. During 3D printing, both the thermally conductive agent and the fusing agent are used to pattern the build material and expose it to electromagnetic radiation to initiate coalescence of the polymer in the build material composition.

[0212] Building material

[0213] In Embodiment 2, the build material comprises thermoplastic polyurethane particles 12. The thermoplastic polyurethane particles of the build material for Embodiment 2 are the same as the thermoplastic polyurethane particles of the build material composition for Embodiment 1 described above.

[0214] In the example, the build material consists of thermoplastic polyurethane particles 12. In other words, the build material does not contain any additional components (including the filler 14 described in the build material composition 10 of Embodiment 1), and thus, the build material is 100% thermoplastic polyurethane particles 12. In another example, the build material can include one or more additives such as antioxidants, whitening agents, antistatic agents, flow aids, or combinations thereof, as described with reference to the build material composition 10 of Embodiment 1.

[0215] Thermal conductivity agent

[0216] Examples of the thermally conductive agent include an aqueous carrier and a thermally conductive filler dispersed in the aqueous carrier (shown as Figure 2 14’ in). The thermally conductive agent is a fluid, and deposition of the thermally conductive agent is achieved using inkjet technology during 3D printing, thereby achieving deposition of the thermally conductive filler 14’. Additionally, the thermally conductive filler 14’ in the thermally conductive agent does not have an adverse effect on the mechanical properties of the 3D printed article.

[0217] The thermal conductive filler 14' is selected from the group consisting of cubic boron nitride and diamond-like carbon. The chemical, physical, and mechanical properties of the cubic boron nitride and diamond-like carbon that can be used as the thermal conductive filler 14' are the same as those of the cubic boron nitride and diamond-like carbon described herein, with the limitation that the size of the filler 14' is specifically selected such that it can be ejected from an inkjet printer.

[0218] Thus, in the case where the thermal conductive filler 14' is cubic boron nitride nanoparticles, the cubic boron nitride nanoparticles have a particle size of, for example, from about 8 nm to about 300 nm. In another example, the cubic boron nitride nanoparticles have a particle size of from about 8 nm to about 150 nm. Similarly, in the case where the thermal conductive filler 14' is diamond-like carbon nanoparticles, the diamond-like carbon nanoparticles have a particle size of, for example, from about 3 nm to about 300 nm. In another example, the diamond-like carbon nanoparticles have a particle size of from about 8 nm to about 150 nm.

[0219] In an example, the thermal conductive filler 14' can be self-dispersible. The self-dispersible thermal conductive filler 14' includes cubic boron nitride or diamond-like carbon nanoparticles having organic groups attached to their surfaces. The organic groups are selected from the group consisting of carboxylates, fatty acid chains, sulfonyl groups, and poly(ethylene glycol). The surface modification of the thermal conductive filler 14' may depend on the ability to modify the surface of the filler 14' with NaOH or HNO3 to produce hydroxyl groups (-OH), which can react with a silane coupling agent containing the listed organic dispersing groups.

[0220] In some examples, cubic boron nitride or diamond-like carbon in solid powder form is added to a liquid carrier to form a thermal conductive agent.

[0221] In other examples, the thermal conductive filler 14' is present in a dispersion before being incorporated into the thermal conductive agent. As an example, cubic boron nitride nanopowder can be mixed with water to form a CBN dispersion, which is then mixed with a liquid carrier to form a thermal conductive agent. As another example, diamond-like carbon is commercially available in the form of an aqueous dispersion. In these examples, the thermal conductive filler 14' is present in the dispersion in an amount in the range of from about 0.5 wt% to about 50 wt%, based on the total weight of the dispersion. In another example, the thermal conductive filler 14' is present in the dispersion in an amount in the range of from about 10 wt% to about 50 wt%, based on the total weight of the dispersion. It should be understood that any liquid component of the dispersion becomes part of the thermal conductive agent.

[0222] The solid form of the thermal conductive filler 14' or a dispersion containing the thermal conductive filler 14' can be combined with a liquid carrier component to form a thermal conductive agent. The solid form or dispersion can be added such that the amount of the thermal conductive filler 14' present in the thermal conductive agent is up to about 15 wt% active based on the total weight of the thermal conductive agent. In another example, the thermal conductive filler 14' is present in an amount of about 1 wt% active to about 10 wt% active based on the total weight of the thermal conductive agent. In another example, the thermal conductive filler 14' is present in an amount of about 4 wt% active to about 6 wt% active based on the total weight of the thermal conductive agent. In a specific example, the thermal conductive filler 14' is present in an amount of about 5 wt% active based on the total weight of the thermal conductive agent.

[0223] The aqueous carrier for the thermal conductive agent includes water, a co-solvent, and additives selected from the group consisting of surfactants and / or dispersants, anti-scaling agents, anti-microbial agents, pH buffers, and combinations thereof. Any examples of co-solvents, surfactants, anti-scaling agents, anti-microbial agents, pH buffers for the fusing agent carrier (FA carrier) described above in connection with Embodiment 1 can also be used for the liquid carrier of the thermal conductive agent in Embodiment 2. However, the loading amounts of the individual components of the liquid carrier for the thermal conductive agent may be different from those of the FA carrier. The loading amount of each individual component of the liquid carrier of the thermal conductive agent is described below.

[0224] Based on the total weight of the thermal conductive agent, the co-solvent(s) can be present in the liquid carrier in an amount of about 1 wt% active to about 50 wt% active. In an example, the liquid carrier contains about 5 wt% active to about 30 wt% active co-solvent(s).

[0225] Based on the total weight of the thermal conductive agent, the total amount of surfactant(s) (whether a single surfactant or a combination of multiple surfactants is used) in the liquid carrier is about 0.01 wt% active to about 3 wt% active. In an example, based on the total weight of the thermal conductive agent, the total amount of surfactant(s) in the liquid carrier is about 0.85 wt% active.

[0226] It may be desirable to have a dispersant separate from the surfactant to disperse the filler 14' throughout the carrier of the thermal conductive agent. Some specific examples of suitable dispersants include water-soluble styrene-acrylic copolymers / resins (e.g., the 60 series, 400 series, or 600 series) available from BASF Corporation or water-soluble styrene-maleic anhydride or styrene maleimide dispersants from Cray Valley / Polyscope or BYK Additives and Instruments. When a dispersant is included, the dispersant can be present in the thermal conductive agent at a weight ratio of filler 14' to dispersant of 5:1 or 10:1.

[0227] Based on the total weight of the heat transfer agent, the anti-scaling agent is present in the liquid carrier in an amount of about 0.1 wt% active to about 1.5 wt% active. In an example, based on the total weight of the heat transfer agent, the anti-scaling agent is present in an amount of about 0.5 wt% active.

[0228] Based on the total weight of the heat transfer agent, the total amount of the antimicrobial agent(s) in the liquid carrier is about 0.01 wt% active to about 0.5 wt% active. In an example, based on the total weight of the heat transfer agent, the amount of the antimicrobial agent(s) is about 0.32 wt% active.

[0229] Based on the total weight of the heat transfer agent, the total amount of the buffer agent(s) in the liquid carrier is about 0.01 wt% active to about 3 wt% active. In an example, based on the total weight of the heat transfer agent, the buffer agent(s) is present in an amount of about 0.1 wt% active.

[0230] The balance of the liquid carrier of the heat transfer agent is water (e.g., deionized water or another form of purified water).

[0231] Flux

[0232] Any fusing agent 18 described herein with reference to Embodiment 1 can be used with the heat transfer agent in Embodiment 2.

[0233] 3D printing kit

[0234] The heat transfer agent can be used as part of a multifluid kit with the fusing agent(s) described herein (e.g., with a UV light fusing agent, with both a core and primer fusing agent, etc.). Some examples of the multifluid kit also include a refining agent and / or a coloring agent described with reference to Embodiment 1.

[0235] The heat transfer agent can be used as part of a 3D printing kit with a build material. One or more of the fusing agents described above for Embodiment 1 are also included in the 3D printing kit. In one example, the 3D printing kit is a single fusing agent kit that includes a build material, a heat transfer agent, and a single fusing agent (such as a core fusing agent or a primer fusing agent or a UV light fusing agent or a color fusing agent). In another example, the 3D printing kit is a multi-fusing agent kit that includes a build material, a heat transfer agent, and two or more fusing agents (such as a core fusing agent and a primer fusing agent). The 3D printing kit can also include other fluids such as a refining agent and / or a coloring agent. The details of the refining agent and / or the coloring agent were described above with reference to Embodiment 1.

[0236] It should be understood that the fluids of the multi-fluid kit or the (multiple) fluids and build materials of the 3D printing kit can be maintained separately until they are used together in the examples of the 3D printing methods described below. The (multiple) fluids and / or build materials can be individually contained in one or more containers before and during printing, but can be combined during printing. The container can be any type of vessel (e.g., reservoir), cartridge, or receptacle made of any material.

[0237] 3D printing method

[0238] The following refers to Figure 2 A 3D printing method using a heat transfer agent is described. The 3D printing method utilizes a 3D printing system 200. The printing system 200 is similar to the printing system 100 and includes a build area platform 102 having a build surface 104 on which a 3D printed article is built. The 3D printing system 200 further includes a build material supply source 106 for containing the build materials described in Embodiment 2, a build material dispenser 108 coupled to the build material supply source 106, and a heat source such as a radiation source 110. The components 102, 104, 106, 108, and 110 are the same physical components that operate in the same manner as the 3D printing system 100 for Embodiment 1 previously.

[0239] The 3D printing system 200 further includes at least two applicators 212, 212', each applicator being coupled to a fluid supply source (not shown), and each applicator being adapted to independently dispense a corresponding fluid. One of the applicators 212 is adapted to dispense a heat transfer agent 32 (including a heat transfer filler 14') onto (multiple) selected portions of a build material 10' (which is thermoplastic polyurethane particles 12 with or without the build material additives described herein) according to a 3D digital model (described below). The other applicator 212' is adapted to also dispense a fusing agent 18 onto (multiple) selected portions of the build material composition 10 according to the 3D digital model. In an example, each applicator 212, 212' includes a thermal inkjet print head, a piezoelectric print head, a continuous inkjet print head, etc., and the selective application of the heat transfer agent 32 and the fusing agent 18 can be accomplished by thermal inkjet printing, piezoelectric inkjet printing, continuous inkjet printing, etc. Other devices capable of using inkjet technology to eject fluids are also contemplated for the applicators 212, 212'.

[0240] In an example, the 3D printing system 200 further includes at least one additional applicator 212”, and another fluid 22, such as a refining agent or a colorant, can be dispensed from the at least one additional applicator 212”. The at least one additional applicator 212” includes any one of the above-described inkjet print heads and corresponding inkjet technologies. Additionally, the applicators 212, 212’, 212” can be separate applicators, or can also be a single applicator having a number of separate cartridges for dispensing the respective fluids. When more than two fluids are used, additional applicators can also be used.

[0241] The printing system 200 further includes a controller (not shown). The controller is configured to access data stored in a data repository related to the 3D article to be built. In an example, the data includes a 3D digital model of the 3D article to be built, and additional data such as the number of build material layers 16’ to be formed, and the locations where the fluid will be deposited on one or more build material layers 16’.

[0242] Details of the 3D printing method for Embodiment 2 will now be described. The 3D printing method includes the step of applying a build material 10’ to form a build material layer 16, where the build material 10’ includes thermoplastic polyurethane particles 12 without fillers 14, and may or may not have one or more build material additives described herein. The step of applying the build material 10’ includes ejecting a predetermined amount of the build material 10’ from a supply source 106 and pushing it onto the surface 104 of a build area platform 102 via a build material dispenser 108. In an example, the build area platform 102 is programmed (by the controller) to advance a sufficient distance in the direction of arrow A (shown in Figure 2 ) so that the build material dispenser 108 can push the build material 10’ onto the build area platform 102. For example, when the 3D printed article has been built and thus the 3D printing method is complete, the build area platform 102 can further be programmed to return to its original position.

[0243] The method further includes the step of spreading the build material 10’. Spreading is effected by moving the dispenser 108 in the Y direction in the X-Y plane of the platform 102 to form a generally uniform layer 16’ of the build material 10’. Thereafter, the dispenser 108 returns to a position adjacent to the supply source 106. In some cases, the supply source 106 or a portion of the supply source 106 is translated with the dispenser 108 so that the build material 10’ is continuously conveyed to the build area platform 102, rather than being supplied from a single position at the side of the printing system 200 as Figure 2 shown.

[0244] In an example, a supply source 106 supplies a build material 10' into a position such that the build material 10' is ready to be spread onto a build area platform 102. A build material dispenser 108 spreads the supplied build material 10' onto the build area platform 102. A controller processes "control build material supply source" data and, in response, controls the supply source 106 to position thermoplastic polyurethane particles 12 appropriately. The controller also processes "control spreader data" and, in response, controls the dispenser 108 to spread the build material 10' onto the build area platform 102 to form a build material layer 16'. In Figure 2 a build material layer 16' has been formed.

[0245] The formed build material layer 16' has a generally uniform thickness on the build area platform 102. In an example, the build material layer 16' has a thickness of from about 50 μm to about 120 μm. In another example, the thickness of the build material layer 16' is from about 30 μm to about 300 μm. It should be understood that thinner or thicker layers may also be used. For example, the thickness of the build material layer 16' may be from about 20 μm to about 500 μm. In the minimum layer thickness for finer part definition, the layer thickness may be about 2x (i.e., 2 times) the average particle size (e.g., diameter) of the thermoplastic polyurethane particles 12. In some examples, the layer thickness may be about 1.2 times the average diameter of the thermoplastic polyurethane particles 12 in the build material 10'.

[0246] After the build material 10' has been applied and spread and before further processing, the method includes the step of preheating the build material layer 16'. The preheating may be carried out as described with reference to Embodiment 1.

[0247] After the build material layer 16' has been formed and in some cases preheated, the method further includes selectively applying a fusing agent 18 and a heat conducting agent 32 respectively on the same part(s) of the build material layer 16' based on a 3D digital model to form at least one patterned part 20'. In this exemplary method, the fusing agent 18 is applied to define the part(s) 20' of the layer 16' that will become part of the 3D printed particle layer 24, and the heat conducting agent 32 is applied to the same part(s) 20' to increase the thermal conductivity of the build material 10' in the part(s) 20'.

[0248] As described above, the thermal agent 32 is dispensed from the applicator 212. In an example, the controller processes data and, in response, controls the applicator 212 to deposit the thermal agent 32 onto the (multiple) predetermined portions 20' of the build material layer 16'. The amount of the thermal agent 32 applied to the build material layer 16' depends on the loading of the filler 14' in the thermal agent 32 and the desired loading of the filler 14' throughout the layer 16'. In an example, sufficient thermal agent 32 is added to the build material layer 16' such that about 1 wt% to about 10 wt% of the filler 14' is added to the portion 20' (where the weight is based on the combined weight of the build material and the filler 14' in the portion 20').

[0249] The thermal filler 14' is dispersed throughout the liquid carrier of the thermal agent 32. When the thermal agent 32 is applied to the (multiple) portions 20', the filler 14' can be homogeneously introduced into the (multiple) portions. This enables the (multiple) portions 20' to exhibit generally uniform enhanced thermal properties (e.g., conductivity).

[0250] As described above, the fusing agent 18 is dispensed from the applicator 212'. In an example, the controller processes data and, in response, controls the applicator 212' to deposit the fusing agent 18 onto the (multiple) predetermined portions 20' of the build material layer 16'.

[0251] Any one of a core fusing agent, a primer fusing agent, a UV light fusing agent, or a colored fusing agent can be used as the fusing agent 18. When it is desired to form a white, colored, or slightly colored layer 24' of the 3D printed article, the primer fusing agent or the UV light fusing agent or the colored fusing agent can be used to pattern the layer 16' of the build material 10'. The primer fusing agent or the UV light fusing agent is transparent or slightly colored (depending on the energy absorber used), and thus the final layer of the 3D printed article may appear white, light-colored (e.g., yellow), or the color of the build material 10'. The colored fusing agent can impart a specific color (e.g., cyan, blue, magenta, etc.) to the 3D printed article. When it is desired to form a darker color or a black layer, the core fusing agent can be used. The core fusing agent is dark or black, and thus the final layer of the 3D printed article may appear gray, black, or another dark color. Using two or more fusing agents 18 can also be used to pattern different portions of a single build material layer.

[0252] The amount of the fusing agent 18 applied to the build material layer 16' to form the (multiple) patterned portions 20' should be sufficient to absorb and convert sufficient electromagnetic radiation such that the build material 10' in the (multiple) patterned portions 20' will coalesce / fuse. The amount of the fusing agent 18 applied depends at least in part on the energy absorber used, the energy absorber loading in the fusing agent 18, and the amount of the heat conducting agent 32 (in particular the filler 14') applied with the fusing agent 18. In particular, the concentration of the energy absorber in the fusing agent 18 can be considered. This concentration can be used to determine how much fusing agent 18 to apply to achieve a weight ratio of the fusing agent 18 to the build material 10', and thus to achieve acceptable layer-by-layer fusing. Thus, if the fusing agent 18 (10 wt%) is applied to the build material 10' (90 wt%) at a weight ratio of about 1:9, the weight ratio of the energy absorber to the build material 10' (as applied) can be from about 1:9000 to about 1:22.5. If more (up to 20 wt%) or less (down to 5 wt%) of the fusing agent 18 is applied to the build material 10', these ratios can be adjusted accordingly.

[0253] The selective application of the heat conducting agent 32 and the fusing agent 18 can be done independently in a single print pass or in multiple print passes. In some examples, the heat conducting agent 32 is selectively applied during a single print pass and then the fusing agent 18 is selectively applied during a single print pass. In some other examples, the heat conducting agent 32 is selectively applied during multiple print passes and then the fusing agent 18 is selectively applied during multiple print passes. In still other examples, the fusing agent 18 is applied before the heat conducting agent 32, or both agents 18, 32 are applied during the same (multiple) print pass. The multiple print passes for each application of the heat conducting agent 32 and the fusing agent 18 are, for example, from 1 to 8 passes.

[0254] In Figure 2 the example shown, another fluid 22 is a refiner which is selectively applied to the (multiple) portions 36' of the layer 16' that are outside the (multiple) patterned portions 20'. These (multiple) portions 36' are not patterned with the fusing agent 18 and thus will not become part of the final 3D printed article layer 24'. The heat energy generated during radiation exposure can propagate into the (multiple) surrounding portions 36' where the fusing agent 18 is not applied. When the refiner is applied to the (multiple) non-patterned build material portions 36', the propagation of the heat energy can be inhibited and thus the coalescence of these (multiple) portions 36' can be prevented. While Figure 2Although not shown, the fining agent may also or alternatively be applied to the (multiple) patterned portions 20' together with the fusing agent 18 and the thermal conductor 32 to reduce the degree of melting in the (multiple) patterned portions 20'. In these examples, the amount of the applied fining agent (other fluid 22) should be low enough that melting is not completely inhibited.

[0255] After the reagents 32, 18 are selectively applied to the (multiple) predetermined portions 20' of the build material layer 16', the entire layer 16' is exposed to electromagnetic radiation (shown as Figure 2 the EMR in). The electromagnetic radiation is emitted from a radiation source 110. In some examples, the electromagnetic radiation has a wavelength of 100 nm to 400 nm, 400 nm to 4000 nm, or 800 nm to 1400 nm, or 800 nm to 1200 nm. The radiation used depends on the fusing agent 18 used. Radiation within an appropriate wavelength range can be absorbed by the fusing agent 18 and can heat the build material 10' in contact therewith and may not be absorbed by the unpatterned build material 10' (e.g., in the (multiple) portions 36').

[0256] In this exemplary method, the electromagnetic radiation exposure can be carried out in the same manner as described with reference to Figure 1 In this example, the length of time of applying the electromagnetic radiation or the energy exposure time can depend, for example, on one or more of the following: the characteristics of the radiation source 110; the characteristics of the build material 10'; the characteristics of the thermal conductor 32; and / or the characteristics of the fusing agent 18. In addition, the presence of the filler 14' in the (multiple) portions 20' can reduce the amount of time required for electromagnetic radiation exposure. Any exposure time in Embodiment 1 can be used in Embodiment 2.

[0257] The electromagnetic radiation exposure can be completed in a single radiation event or in multiple radiation events. In an example, the number of radiation events is in the range of 1 to 8. It may be desirable to expose the build material composition 10 to electromagnetic radiation in multiple radiation events to counteract the cooling effect that may be brought about by the amounts of the thermal conductor 32 and the fusing agent 18 applied to the build material layer 16'. Additionally, it may be desirable to expose the build material layer 16' to electromagnetic radiation in multiple radiation events to sufficiently raise the temperature of the build material 10' in the (multiple) patterned portions 20 without overheating the build material 10' in the (multiple) non-patterned portions 36'.

[0258] The flux 18 enhances the absorption of radiation, converts the absorbed radiation into heat energy, and facilitates the transfer of the heat energy to the build material 10' in contact therewith. The enhanced thermal conductivity of the build material 10' obtained by selectively applying the filler 14' enables the (multiple) patterned portions 20' to reach the melting range of the thermoplastic polyurethane particles 12 more efficiently than in the absence of the filler 14'. Thus, the combination of the filler 14' and the flux 18 sufficiently raises the temperature of the build material 10' in the patterned portions 20' to a temperature higher than the minimum melting temperature of the thermoplastic polyurethane particles 12, thereby allowing coalescence / fusion (e.g., thermal merging, melting, bonding, etc.) of the build material 10' to occur. The application of electromagnetic radiation forms the layer 24' of the 3D printed article.

[0259] After the layer 24' of the 3D printed article has been formed, (multiple) additional layers can be formed thereon to create an example of a 3D printed article. To form the next layer, additional build material 10' is applied to the layer 24' of the 3D printed article. Then, according to the data received from the 3D digital model, a thermal conductor 32 is selectively applied to at least a portion of the additional build material 10'. Then, according to the data obtained from the 3D digital model, the flux 18 and the thermal conductor 32 are selectively applied to the (multiple) portions 20' of the additional build material 10' respectively. After the thermal conductor 32 and the flux 18 have been applied, the entire layer of the additional build material 10' is exposed to electromagnetic radiation in the above-described manner. The application of the additional build material 10', the selective application of the thermal conductor 32, the selective application of the flux 18, and the electromagnetic radiation exposure can be repeated for a predetermined number of cycles to form the final 3D printed article according to the 3D digital model. Details of the 3D printed article are described below.

[0260] A 3D printed article produced using the method of Embodiment 2 may appear darker in color when using a core flux, or may appear white or the color of the build material composition 10 when using a primer or a UV flux, or may be slightly colored when using a UV flux, or may be a specific color when using a colored flux. For a 3D printed article with a lighter color, color can be added during 3D printing or after the 3D printed article is produced by using a separate colorant.

[0261] In one example, the method further includes selectively applying a colorant to the (multiple) patterned portions 20' based on a 3D object model. In this example, the colorant is applied to the build material 10' together with the flux 18 and the thermal conductor 32. In this example, the colorant of the colorant is embedded in the entire coalesced / fused build material 10' of the 3D article layer 24'. To introduce color, it may be desirable to introduce the colorant into the patterned portions 20' that define the edge boundaries of the 3D printed article being formed.

[0262] In yet another example, the method further includes selectively applying a colorant to the 3D printed article layer 24' (after coalescence occurs) based on the 3D object model. In this example, the colorant is applied to the outer surface of the 3D printed article layer 24'.

[0263] In the examples disclosed herein, the 3D printed article can be printed in any orientation. For example, the 3D printed article can be printed from bottom to top, from top to bottom, from the side, at an angle, or in any other orientation. The orientation of the 3D object can also be formed in any orientation relative to the layering of the build material 10'. For example, the 3D printed article can be formed in an inverted orientation or on its side relative to the layering of the build material 10'. For example, the build orientation within each layer 16' can be preselected or even selected by the user during printing.

[0264] 3D printed article

[0265] Each 3D printing method in Embodiment 1 and Embodiment 2 forms a 3D printed article. As Figure 3 shown, the 3D printed article 40 includes a plurality of coalesced thermoplastic polyurethane particle layers 24 or 24' and a thermally conductive filler 14 or 14' and an energy absorber incorporated throughout the coalesced thermoplastic polyurethane particles. Based on the total weight of the 3D printed article 40, the coalesced thermoplastic polyurethane particles are present in an amount of about 90 wt% to about 99 wt%. Based on the total weight of the 3D printed article, the thermally conductive filler 14 or 14' is present in an amount of about 1 wt% to about 10 wt% and is selected from the group consisting of cubic boron nitride and diamond-like carbon. In the case where the thermally conductive filler 14 or 14' is cubic boron nitride, in a particular example, cubic boron nitride is present in an amount of about 5 wt% based on the total weight of the 3D printed article 40. In the case where the thermally conductive filler 14 or 14' is diamond-like carbon, in a particular example, diamond-like carbon is present in an amount of about 5 wt% based on the total weight of the 3D printed article 40. Generally, other liquid carrier components such as water, co-solvents, etc. will evaporate during processing and, therefore, a negligible amount will remain in the final 3D printed article.

[0266] Although four layers 24, 24' are shown in Figure 3 , the 3D printed article 40 can have the desired number of layers 24, 24' to form the 3D printed article 40. Additionally, for illustrative purposes, Figure 3 an enlarged single layer 24, 24' is depicted. It should be understood that the single layer 24, 24' has a much smaller thickness than shown, for example, on the order of about 20 μm to about 200 μm as described above. Additionally, once the layers 24, 24' are formed, the layers 24, 24' coalesce at the respective interfaces to form a single unit.

[0267] To further illustrate the present disclosure, examples are presented herein. It should be understood that these examples are provided for descriptive purposes and should not be construed as limiting the scope of the present disclosure.

[0268] Example

[0269] Example 1

[0270] Six samples (BM1, BM2, BM3, BM4, BM5, BM6) of the construction material composition were prepared. One type of thermoplastic polyurethane powder (from BASF Corp.) was used for three of these samples (BM1, BM2, BM3), and another type of thermoplastic polyurethane powder (from Lubrizol Corp.) was used for the other three samples (BM4, BM5, BM6). The construction material compositions BM1 and BM4 were each prepared by mixing 95 wt% of the thermoplastic polyurethane powder with 5 wt% of cubic boron nitride (purity 99.99%) to form a dry blend. The construction material compositions BM3 and BM6 were each prepared by mixing 95 wt% of the thermoplastic polyurethane powder with 5 wt% of diamond-like carbon to form a dry blend. The construction material compositions BM1, BM3, BM4, and BM6 represent the construction material compositions of the present disclosure (cubic boron nitride or diamond-like carbon is the thermal conductive filler).

[0271] The construction material compositions BM2 and BM5 each consisted of the respective thermoplastic polyurethane powder (i.e., 100 wt% of the thermoplastic polyurethane powder, without any added filler). Thus, the construction material compositions BM2, BM5 are comparative samples.

[0272] A number of tests were performed using each of the samples BM1, BM3, BM4, BM6 and each of the comparative samples BN2, BN5 to determine the effect of the filler on the thermal properties of the construction material composition. Briefly summarizing the results, each of the samples BM1, BM3, BM4, BM6 (with filler) showed improvement in their thermal properties (in terms of thermal conductivity, enthalpy, and thermal window) compared to the comparative samples BN2, BN5 (without filler).

[0273] Thermal conductivity

[0274] The thermal stability of all six samples (BM1, BM2, BM3, BM4, BM5, BM6) was tested using the transient plane source (TPS) method.

[0275] The thermal conductivity of each sample was determined at temperatures of 21 °C, 50 °C, 75 °C, 100 °C, 125 °C, 150 °C and 200 °C, and the results are presented in the Figure 4 depicted graph. The results show that samples BM1, BM3, BM4, BM6 (including one of the thermal conductive fillers) have significantly higher thermal conductivity values (from about 0.110 W / m·K to about 0.150 W / m·K) compared to the comparative samples BM2, BM5 (from about 0.060 W / m·K to about 0.070 W / m·K). These results indicate that the thermal conductivity is increased by the presence of any one of these fillers in the construction material composition.

[0276] Melting enthalpy

[0277] The enthalpy of fusion, also known as the heat of fusion, is the thermal energy required to change the physical state of a substance (i.e., thermoplastic polyurethane) from solid to liquid, expressed in joules per gram (J / g). The enthalpy of fusion of each of the six samples was determined using differential scanning calorimetry (DSC).

[0278] In the Figure 5 depicted graph, the enthalpy of fusion (J / g) of the six samples is shown. The results show that the enthalpy of fusion of samples BM1, BM3, BM4, BM6, which include one of the thermal conductive fillers, is significantly reduced compared to the comparative samples BM2, BM5. The reduction in the enthalpy of fusion indicates that any one of the fillers in the construction material composition can result in faster melting compared to the comparative samples without any filler.

[0279] Crystallization enthalpy

[0280] The enthalpy of crystallization, also known as the heat of crystallization, is the thermal energy absorbed (J / g) when one mole of a substance (e.g., TPU) crystallizes from a saturated solution of the same substance. The enthalpy of crystallization of each of the six samples was also determined using DSC.

[0281] In the Figure 6 depicted graph, the enthalpy of crystallization (J / g) of the six samples is shown. Similar to the enthalpy of fusion, the results show that the enthalpy of crystallization of samples BM1, BM3, BM4, BM6, which include the thermal conductive filler, is significantly reduced compared to the comparative samples BM2, BM5.

[0282] Thermal window

[0283] The thermal window is the difference between the end of the melting transition and the start of the crystallization transition. The thermal window of each of the six samples was determined using DSC.

[0284] In the Figure 7The thermal window (°C) of six samples is depicted in the figure shown. The results indicate that, compared with the comparative samples BM2 and BM5, the thermal conductive fillers in samples BM1, BM3, BM4, and BM6 increased the thermal window of the construction material composition. For example, the thermal windows of samples BM1 and BM4, each including cubic boron nitride, are approximately 12.7 °C and 13.75 °C respectively, while in contrast, the thermal window of the comparative sample BM2, containing the same type of thermoplastic polyurethane but no filler, is approximately 11.25 °C. Compared with the comparative sample BM5, which contains the same type of thermoplastic polyurethane but no filler, a more significant increase in the thermal window is shown for samples BM3 and BM6, each including diamond-like carbon. In particular, the thermal window of sample BM3 is approximately 22.5 °C and the thermal window of sample BM6 is approximately 18.75 °C, while the thermal window of the comparative sample BM5 is approximately 11.5 °C.

[0285] Example 2

[0286] The six samples (BM1, BM2, BM3, BM4, BM5, BM6) prepared in Example 1 were used in Example 2. Each of the six samples was tested to determine the effect of the presence of the filler on the mechanical properties of the construction material composition. Briefly summarizing the results, the tests showed that, compared with the comparative samples without filler (BN2, BN5), there were slight and insignificant changes in the mechanical properties of the thermoplastic polyurethane in the samples with filler (BN1, BN3, BN4, BN6). This means that neither of the two fillers had a significant impact on the integrity of the thermoplastic polyurethane.

[0287] Young's modulus

[0288] The Young's modulus or elastic modulus is a mechanical property of a material that measures the tensile or compressive stiffness of the material when a force is applied longitudinally. Essentially, the Young's modulus is an indicator of how easily a material can be stretched and deformed. The Young's modulus of each of the samples BM1, BM2, BM3, BM4, BM5, and BM6 was determined using the tensile pull method (ASTM 680).

[0289] In Figure 8 The Young's modulus of each of the samples BM1, BM2, BM3, BM4, BM5, and BM6 is shown in the bar graph depicted. As shown, the modulus of the construction material samples with filler (BN1, BN3, BN4, BN6) was determined to be from approximately 65 MPa to approximately 80 MPa, while the modulus of the comparative samples (BN2, BN5) was determined to be from approximately 60 MPa to approximately 80 MPa. Therefore, the Young's modulus of the samples including the filler remained roughly the same as that of the comparative samples.

[0290] Elongation at break

[0291] The elongation at break, also known as the breaking strain, is a property of a material that shows the resistance of the material to changing shape or breaking.

[0292] In Figure 9 The elongation at break of each of the samples BM1, BM2, BM3, BM4, BM5, BM6 is shown in the bar graph depicted. As shown, the elongation at break of the samples of the construction material containing fillers (BN1, BN3, BN4, BN6) was determined to be from about 200% to about 230%, while the elongation at break of the comparative samples (BN2, BN5) was determined to be from about 190% to about 225%. Thus, the elongation at break of the samples including fillers is generally the same as that of the comparative samples.

[0293] Example 3

[0294] In this example, polypropylene was used as the basis of the construction material composition, and thus all samples were comparative samples (since they did not include thermoplastic polyurethane particles).

[0295] Six samples of polypropylene-based construction material compositions (PPBM7 to PPBM12) were prepared. Polypropylene powder was used for all six samples. The construction material compositions PPBM7 and PPBM8 were prepared by mixing 95 wt% of polypropylene powder with 5 wt% of cubic boron nitride (purity 99.99%) to form a dry blend, respectively. The construction material compositions PPBM10 and PPBM11 were prepared by mixing 95 wt% of polypropylene powder with 5 wt% of diamond-like carbon to form a dry blend, respectively. The construction material compositions PPBM9 and PPBM12 each consisted of polypropylene powder (i.e., 100 wt% of polypropylene powder, without any added fillers).

[0296] Heat capacity

[0297] The thermal stability of all six comparative samples (PPBM7 - PPBM12) was tested using differential scanning calorimetry (DSC). This test is an analytical technique that measures the change in heat capacity of a sample as a function of temperature. The test conducted in a differential scanning calorimeter involves simultaneously introducing thermal energy into a sample cell (containing the corresponding comparative sample) and a blank reference cell while increasing the temperature of both cells in the same manner over time. Since the compositions of the specific comparative sample and the blank reference are different, different amounts of energy are required to raise the temperature of the cells. The excess energy required to compensate for the temperature difference between the cells is measured as the heat capacity as a function of temperature. The heat capacity was tested at the following temperatures: 25 °C, 50 °C, 100 °C, 150 °C and 200 °C, and at Figure 10(PPBM7 - PPBM9) and Figure 11 The results are illustrated in the figures depicted by (PPBM10 - PPBM12). Figure 10 and Figure 11 The results in and respectively show that adding cubic boron nitride and diamond - like carbon to polypropylene powder hardly improves the thermal conductivity of the polypropylene powder.

[0298] It should be understood that the ranges provided herein include the stated range and any value or sub - range within that range. For example, a range of about 90 wt% to about 99 wt% should be interpreted to include not only the explicitly recited limits of about 90 wt% to about 99 wt%, but also individual values such as 95 wt%, 91.5 wt%, 97 wt%, 97.25 wt%, etc., and sub - ranges such as about 90.5 wt% to about 98 wt%, about 92 wt% to about 97 wt%, etc. Additionally, when using "about" to describe a value, it is intended to cover minor variations (up to + / - 10%) relative to the stated value.

[0299] Throughout the specification, references to "one example", "another example", "an example", etc. mean that a particular element (e.g., a feature, a structure, and / or a property) described in connection with the example is included in at least one example described herein and may or may not be present in other examples. Further, it should be understood that, unless the context clearly indicates otherwise, the elements of any example can be combined in any suitable manner in various examples.

[0300] In describing and claiming the examples disclosed herein, unless the context clearly indicates otherwise, the singular forms "a / an" and "the" include plural referents.

[0301] Although several examples have been described in detail, it should be understood that modifications can be made to the disclosed examples. Accordingly, the above description should be regarded as non - limiting.

Claims

1. A build material composition for 3D printing, the build material composition comprising: Thermoplastic polyurethane particles present in an amount of about 90 wt% to about 99 wt% based on the total weight of the build material composition; and A thermal conductive filler present in an amount of about 1 wt% to about 10 wt% based on the total weight of the build material composition, the thermal conductive filler selected from the group consisting of cubic boron nitride and diamond-like carbon.

2. The build material composition according to claim 1, wherein the thermal conductive filler is present in an amount of about 4 wt% to about 6 wt% based on the total weight of the build material composition.

3. The build material composition according to claim 1, wherein the thermal conductive filler comprises thermally conductive nanoparticles, and the build material composition is a dry blend of the thermoplastic polyurethane particles and the thermally conductive nanoparticles.

4. The build material composition according to claim 3, wherein: The thermally conductive nanoparticles are cubic boron nitride nanoparticles with an average particle size of about 70 nm to about 800 nm; or The thermally conductive nanoparticles are diamond-like carbon nanoparticles with an average particle size of about 80 nm to about 600 nm.

5. The build material composition according to claim 1, wherein the build material composition does not contain any additional components.

6. The build material composition according to claim 1, wherein compared with a build material containing only thermoplastic polyurethane particles, the build material composition exhibits improved thermal properties without changing the chemical properties of the thermoplastic polyurethane particles by including the thermal conductive filler.

7. A thermal conductive agent for 3D printing, the thermal conductive agent comprising: An aqueous carrier; and A thermal conductive filler dispersed in the aqueous carrier, the thermal conductive filler present in an amount of about 1 wt% active to about 10 wt% active based on the total weight of the thermal conductive agent, and the thermal conductive filler selected from the group consisting of cubic boron nitride and diamond-like carbon.

8. The thermal conductive agent according to claim 7, wherein the thermal conductive filler comprises self-dispersing thermally conductive nanoparticles.

9. The thermal conductive agent according to claim 8, wherein the self-dispersing thermally conductive nanoparticles comprise the thermally conductive nanoparticles and organic groups attached to the thermally conductive nanoparticles, the organic groups selected from the group consisting of phosphorus-containing groups, carboxyl groups, and sulfonic acid groups.

10. The thermal conductive agent according to claim 8, wherein the thermal conductive filler is present in an amount of about 4 wt% active to about 6 wt% active based on the total weight of the thermal conductive agent.

11. The thermal conductive agent according to claim 10, wherein: The thermally conductive filler particles are cubic boron nitride particles with an average particle size of about 70 nm to about 800 nm; or The thermally conductive nanoparticles are diamond-like carbon particles with an average particle size of about 80 nm to about 600 nm.

12. The thermal conductive agent according to claim 8, wherein the aqueous carrier comprises a co-solvent, a surfactant, and an additive, and the additive is selected from the group consisting of an anti-scaling agent, an anti-microbial agent, a pH buffer, and combinations thereof.

13. A three-dimensional (3D) printed article, the 3D printed article comprising: Coalesced thermoplastic polyurethane particles present in an amount of from about 90 wt% to about 99 wt% based on the total weight of the 3D printed article; A thermal conductive filler incorporated throughout the coalesced thermoplastic polyurethane particles, the thermal conductive filler being present in an amount of from about 1 wt% to about 10 wt% based on the total weight of the 3D printed article, and the thermal conductive filler being selected from the group consisting of cubic boron nitride and diamond-like carbon; and An energy absorber incorporated throughout the coalesced thermoplastic polyurethane particles.

14. The 3D printed article according to claim 13, wherein the thermal conductive filler is cubic boron nitride present in an amount of 5 wt% based on the total weight of the 3D printed article.

15. The 3D printed article according to claim 13, wherein the thermal conductive filler is diamond-like carbon present in an amount of 5 wt% based on the total weight of the 3D printed article.

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