Dispersions for additive manufacturing comprising discrete carbon nanotubes

Abstract

This invention relates to additive manufacturing compositions and methods for producing additive manufacturing composite blends having oxidized discrete carbon nanotubes having a dispersant bonded to at least one sidewall of the oxidized discrete carbon nanotubes. Such compositions are particularly useful when subjected to radiation curing, sintering, or melting.

Description

Technical Field

[0001] This invention relates to additive manufacturing compositions and methods for producing additive manufacturing composite blends having oxidized discrete carbon nanotubes having a dispersant bonded to at least one sidewall of the oxidized discrete carbon nanotubes. Such compositions are particularly useful when subjected to radiation curing, sintering, or melting. Prior Technology

[0002] Additive manufacturing (AM) is an apt name for describing the technology of building 3D entities by adding layers of material, typically crosslinkable monomers or oligomers, polymers, metals, ceramics, and biocompatible materials. AM technology generally uses computers, 3D modeling software (computer-aided design or CAD), machinery, and layered materials. Once a CAD sketch is generated, the AM device reads data from the CAD file and places or adds successive layers of liquid, powder, sheet material, or other materials (such as tape) one after another to create a 3D entity. The term AM encompasses many technologies, including subsets such as 3D printing, rapid prototyping (RP), direct digital manufacturing (DDM), layered manufacturing, and additive manufacturing.

[0003] Liquid radiation-cured resins are selectively crosslinked (or cured) by an energy source (such as a laser). Efforts in UV-cured resin formulations focus on enhancing mechanical properties to achieve similarities to those of commercial plastics and engineered polymers. Improving the mechanical properties of UV-cured resins can be achieved through the development of specialized monomers and curing agents, alteration of chain growth mechanisms, utilization of hybrid polymerization methods, and the addition of additives and fillers. However, many limitations remain due to the need to balance their properties, such as heat distortion resistance, rigidity, and impact strength.

[0004] Adding fillers has been used to meet specific performance requirements, such as stiffness, for selected AM applications. Inorganic fillers (such as SiO2 and Al2O3) have been shown to improve the strength and stiffness of components manufactured by tank photopolymerization, but they typically have much longer, undesirable curing times. Furthermore, these fillers often result in high initial resin viscosity, poor viscosity stability, and exhibit a tendency to separate from the base resin. There remains a need for fillers that do not impose undesirable additional curing times on the base crosslinkable resin formulation.

[0005] Therefore, radiation-cured resins are needed to produce components with enhanced mechanical, thermal, electrical, magnetic, and chemical properties, while meeting stringent requirements for polymer resins, such as high curing rates, low viscosity, excellent stability, and high green strength. In particular, achieving a resistance of at least 10 billion ohms per square meter using conductive carbon black is a challenge due to the aforementioned curing rate requirements.

[0006] For AM methods utilizing powdered materials (metals, ceramics, or polymers), it is necessary to improve their sintering ability and green strength before secondary processing. Binder selection is considered crucial for successful part manufacturing. First, the binder must be sprayable. An ideal binder has low viscosity, is stable under shear stress, interacts well with the powdered raw material, has clean burn-off, and a long shelf life. Common liquid binders include butyral resins, polyethylene compounds, polysiloxanes, polyacrylic acid, and polyether polyurethanes. In some cases, higher-strength polymer binders are required, especially when sintering is performed at higher temperatures.

[0007] Binders used for metal and ceramic powders are typically aqueous or non-aqueous dispersions of inorganic particles, such as silica dispersions, aluminum nitrate dispersions, or film-forming polymer dispersions. Adding nanoparticles to the binder system fills the voids in the powder bed, thus improving sinterability, increasing component density, and reducing shrinkage. As the size of the nanoparticles decreases, their melting point decreases exponentially. Therefore, the nanoparticles in the binder will sinter at a lower temperature than the raw powder, allowing for the fusion of larger particles, thereby improving the green strength of the component. Binders with low ash residue content are required at the sintering or curing temperatures of metals, cermats, or ceramics.

[0008] Binders for polymer powders typically consist of solvents or solvent mixtures that promote the swelling of the polymer raw materials, leading to particle aggregation through interdiffusion and entanglement. Solutions of film-forming polymer dispersions can also be used as binders. Water-based binders are required for processing hydrophilic powders (e.g., starch, gypsum, and cement). Hydrophobic polymer powders (e.g., polylactic acid or PLA) can be treated using organic solvents. These types of binders for polymer powders can also be used to coat thermoplastic filaments for fusion-bonded parts.

[0009] Carbon nanotubes can be classified into single-walled, double-walled, and multi-walled types based on the number of walls within the tube. Each wall of a carbon nanotube can be further classified as chiral or achiral. Some carbon atoms in a carbon nanotube can be replaced by nitrogen atoms. Currently, carbon nanotubes are manufactured as aggregated carbon nanotube spheres or bundles, with very limited commercial applications. The use of carbon nanotubes as reinforcing agents in polymer composites is one area where they are expected to have significant utility. However, their use in these applications is hampered by the generally unreliable production of individualized carbon nanotubes. To realize the full potential of carbon nanotubes as a performance enhancer in polymer composites, the aspect ratio (i.e., the ratio of length to diameter) should be greater than 10. For a given tube length, the maximum aspect ratio is reached when each tube is completely separated from the other. For example, the effective aspect ratio of a carbon nanotube bundle in a composite is the average length of the bundle divided by its diameter.

[0010] Various methods have been developed to untangle or detangle carbon nanotubes in solutions. For example, carbon nanotubes can be significantly shortened by an aggressive oxidation method and then dispersed as individual nanotubes in dilute solutions. These tubes have a low aspect ratio, making them unsuitable for high-strength composites. Carbon nanotubes can also be dispersed as individuals in very dilute solutions by ultrasonication in the presence of surfactants. Exemplary surfactants for dispersing carbon nanotubes in aqueous solutions include, for example, sodium dodecyl sulfate or hexadecyltrimethylammonium bromide. In some cases, solutions of individualized carbon nanotubes can be prepared from polymer-encapsulated carbon nanotubes. Solutions of individualized single-walled carbon nanotubes have also been prepared in very dilute solutions using polysaccharides, peptides, water-soluble polymers, nucleic acids, DNA, polynucleotides, polyimides, and polyvinylpyrrolidone; however, these dilute solutions are not suitable for additive manufacturing. Summary of the Invention

[0011] This invention relates to novel compositions and methods for producing additive manufacturing dispersions and their components.

[0012] In one embodiment, the composition of the present invention includes an additively manufactured dispersion, wherein the dispersion comprises at least a portion of crosslinkable partially oxidized discrete carbon nanotubes, the oxidized discrete carbon nanotubes having a dispersant bonded to at least one sidewall of the oxidized discrete carbon nanotubes, wherein the oxidized discrete carbon nanotubes are present in a range greater than 0 to at most about 30% by weight based on the total weight of the dispersion, and the majority of the carbon nanotubes present in the dispersion are discrete.

[0013] Ideally, the oxidized discrete carbon nanotube includes an inner surface and an outer surface, each surface including an inner surface oxidized material content and an outer surface oxidized material content, wherein the inner surface oxidized material content differs from the outer surface oxidized material content by at least about 20% and up to 100%.

[0014] Oxidized discrete carbon nanotubes may include a mixture of oxidized discrete carbon nanotubes, the mixture being formed by a combination of oxidized discrete single-walled carbon nanotubes, oxidized discrete double-walled carbon nanotubes and oxidized discrete multi-walled carbon nanotubes, having a diameter of oxidized discrete carbon nanotubes with a bimodal or trimodal distribution.

[0015] Ideally, the dispersant bonded to the sidewalls of oxidized discrete carbon nanotubes should be covalently bonded.

[0016] The dispersant bound to the sidewall of the oxidized discrete carbon nanotube ideally comprises an average molecular weight in the range of about 50 to about 20,000 Daltons, and the weight fraction of the dispersant bound to the sidewall of the discrete carbon nanotube relative to the oxidized discrete carbon nanotube is greater than about 0.02 and less than about 0.8.

[0017] The materials of the dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes are ideally miscible with those of the contact-bonded dispersant.

[0018] A second embodiment of the present invention is an additively manufactured dispersion, wherein the dispersion comprises at least a portion of a crosslinkable acrylate portion and an oxidized discrete carbon nanotube, wherein a dispersant is bound to at least one sidewall of the oxidized discrete carbon nanotube, wherein the dispersant bound to the sidewall of the discrete carbon nanotube comprises molecular units selected from the group consisting of ethers.

[0019] The molecular unit of the second implementation scheme ideally includes ethylene oxide.

[0020] The first or second embodiment may further include about 0.1% to about 30% by weight of filler in the dispersion, ideally wherein the filler is selected from the group consisting of carbon black, graphene, graphene oxide, reduced graphene, carbon fiber, silica, silicate, halloysite, clay, calcium carbonate, wollastonite, glass, flame retardant and talc.

[0021] The first or second embodiment may further include members of the group consisting of thermoplastics, thermosettings and elastomers.

[0022] The first or second embodiment may further include a core-shell elastomer, wherein the elastomer ideally comprises particles with a diameter of about 0.01 to about 1 micrometer.

[0023] The first or second embodiment may further include semiconductor powder, metal powder or ceramic powder, wherein the powder comprises particles with a diameter of about 1 nm to about 20 micrometers.

[0024] The first or second embodiment may further include at least one additional dispersant attached to the sidewall of the oxidized discrete carbon nanotube, said additional dispersant being selected from the group consisting of anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants, polyvinyl alcohol, copolymers of polyvinyl alcohol and polyvinyl acetate, polyvinylpyrrolidone and copolymers thereof, carboxymethyl cellulose, carboxypropyl cellulose, carboxymethylpropyl cellulose, hydroxyethyl cellulose, polyetherimide, polyether, starch and mixtures thereof.

[0025] In the first or second embodiment, the oxidized discrete carbon nanotubes comprise about 0.1% to about 20% by weight of nitrogen atoms.

[0026] A third embodiment of the invention is an additive manufacturing dispersion comprising at least a portion of a thermoplastic portion and discrete carbon nanotubes, wherein a bound dispersant is present on at least one sidewall of the discrete carbon nanotubes, wherein the discrete carbon nanotubes are present in an amount greater than 0 to at most about 30% by weight based on the total weight of the dispersion.

[0027] A third embodiment may include a dispersant bonded to the sidewalls of an oxidized discrete carbon nanotube, the dispersant being at least partially thermally decomposed in nitrogen at a temperature below about 500°C with an ash content of less than about 5% by weight.

[0028] The third implementation scheme may include a majority of discrete carbon nanotubes.

[0029] Any of the three implementation schemes may include a component made by additive manufacturing, which has a resistance of less than about 10 billion ohms per square.

[0030] Any of the three implementation schemes may include a dispersion in which the concentration of oxidized discrete carbon nanotubes is 2.5 × 10⁻⁵ g / ml and the dispersion has a UV-Vis absorption at 500 nm greater than about 0.5 absorbance units.

[0031] Any of the three implementations may further include a filler selected from the group consisting of thermally conductive materials, such as, but not limited to, metals and metal alloys, boron nitride, alumina, silicon nitride, aluminum nitride, diamond, graphite, and graphene.

[0032] Any of the three implementation schemes may further include a bioactive substance selected from the group consisting of substances that can interact with bacteria, viruses, fungi and biological agents.

[0033] Oxidized carbon nanotubes are those carbon nanotubes that have been subjected to an oxidizing medium, such as, but not limited to, concentrated nitric acid, peroxides, and persulfates, which introduce chemical units, such as carboxylic acids, hydroxyl groups, ketones, and lactones. Oxidized discrete carbon nanotubes are selected from the group consisting of oxidized discrete single-walled carbon nanotubes, oxidized discrete double-walled carbon nanotubes, or oxidized discrete multi-walled carbon nanotubes.

[0034] The oxidized discrete carbon nanotube may further include an inner surface and an outer surface, each surface including an inner surface oxidized material content (also referred to as an internal oxygen-containing material content, since the internal oxygen-containing material may differ from the external oxygen-containing material) and an outer surface oxidized material content (also referred to as an external oxygen-containing material content, since the internal oxygen-containing material may differ from the external oxygen-containing material), wherein the inner surface oxidized material content differs from the outer surface oxidized material content by at least 20% and up to 100%, ideally wherein the inner surface oxidized material content is less than the outer surface oxidized material content. The inner surface oxidized material content relative to the weight of the carbon nanotube can be up to 3% by weight, ideally about 0.01 to about 3% by weight, more ideally about 0.01 to about 2%, and most ideally about 0.01 to about 1%. Particularly ideally, the inner surface oxidized material content relative to the weight of the carbon nanotube is 0 to about 0.01% by weight. The outer surface oxidized material content relative to the weight of the carbon nanotube can be about 0.1 to about 65% by weight, ideally about 1 to about 40%, and more ideally about 1 to about 20% by weight. This is determined by comparing the amount of externally oxidized material in a given majority of nanotubes with the total weight of that majority of nanotubes.

[0035] The oxidized discrete carbon nanotubes may further comprise a mixture of oxidized discrete carbon nanotubes, formed by a combination of oxidized discrete single-walled carbon nanotubes, oxidized discrete double-walled carbon nanotubes, and oxidized discrete multi-walled carbon nanotubes, having a bimodal or trimodal distribution of the diameter of the oxidized discrete carbon nanotubes. Ideally, the dispersion of oxidized discrete carbon nanotubes comprises a majority of oxidized discrete multi-walled carbon nanotubes, more ideally a majority of oxidized discrete double-walled carbon nanotubes, and even more ideally a majority of oxidized discrete single-walled carbon nanotubes. "Most" means more than 50% by weight of all carbon nanotubes present in the dispersion.

[0036] In another embodiment of the invention, the dispersant bonded to the sidewall of the additively manufactured dispersion—oxidized discrete carbon nanotube—is hydrogen-bonded, ideally ionic-bonded, and more ideally covalently bonded.

[0037] In another embodiment, the oxidized discrete carbon nanotube further comprises a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotube, the bonded dispersant comprising a molecular weight in the range of about 50 to about 20,000 Daltons. Ideally, the molecular weight of the bonded dispersant is in the range of about 60 to about 5,000 Daltons, and more ideally about 70 to about 1,000 Daltons. The dispersant bonded to the sidewalls of the oxidized discrete carbon nanotube comprises chemical units selected from the group consisting of carbon-carbon bonds, carbon-nitrogen bonds, carbon-oxygen bonds, carbon-sulfur bonds, and silicon-oxygen bonds. In the presence of a crosslinkable matrix, the chemical units of the bonded dispersant are ideally crosslinked into the matrix.

[0038] The weight fraction of the dispersant bound to the sidewall of the discrete carbon nanotube is greater than about 0.02 and less than about 0.8 relative to the oxidized discrete carbon nanotube. Ideally, the weight fraction of the bound dispersant is about 0.03 to about 0.6, more ideally about 0.05 to about 0.5, and most ideally about 0.06 to about 0.4.

[0039] The dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes is selected to ensure good compatibility with the material of the contact dispersant. Good compatibility, in this specification, means a sufficient amount of electron, van der Waals force, ionic, or dipole interaction to allow the oxidized carbon nanotubes to be dispersed as single or discrete carbon nanotubes. Ideally, the dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes is selected to be thermodynamically miscible, i.e., to form a homogeneous mixture with the material of the contact dispersant.

[0040] The dispersant bonded to the sidewalls of the discrete carbon nanotubes may further comprise ethylene oxide molecular units. More ideally, the bonded dispersant comprises a mixture of propylene oxide and ethylene oxide molecular units. There may be mixtures of dispersants bonded to the sidewalls of the discrete carbon nanotubes or mixtures of oxidized discrete carbon nanotubes having different types of bonds to the dispersant.

[0041] In another embodiment of the invention, the dispersant bonded to the oxidized discrete carbon nanotube sidewalls may be further selectively thermally decomposed such that the ash content of the dispersant is less than about 5% by weight in nitrogen at a temperature below 500°C. Ideally, the dispersant bonded to the oxidized discrete carbon nanotube sidewalls undergoes thermal decomposition such that the ash content of the dispersant is less than about 1% by weight in nitrogen at a temperature below about 500°C, and more ideally, the dispersant bonded to the oxidized discrete carbon nanotube sidewalls undergoes thermal decomposition such that the ash content of the dispersant is less than about 1% by weight in nitrogen at a temperature below about 400°C.

[0042] Oxidized discrete carbon nanotubes, which have a dispersant bonded to their sidewalls, consist of aspect ratios (referred to as the ratio of the length to the diameter of the oxidized discrete carbon nanotube) of about 10 to about 10,000. For oxidized discrete single-walled carbon nanotubes, the ideal aspect ratio is about 300 to about 10,000; for oxidized discrete double-walled carbon nanotubes, the ideal aspect ratio is about 150 to about 5,000; and for oxidized discrete multi-walled carbon nanotubes, the ideal aspect ratio is about 40 to about 500.

[0043] The aspect ratio of oxidized discrete carbon nanotubes can be unimodal or multimodal (e.g., bimodal or trimodal). A multimodal distribution can have a uniformly distributed range of aspect ratios (e.g., 50% of one L / D range and approximately 50% of another). The distribution can also be asymmetric—meaning a relatively small percentage of discrete nanotubes can have one particular L / D, while a larger number of discrete nanotubes can include a different aspect ratio distribution.

[0044] In one embodiment of the invention, the oxidized discrete carbon nanotubes having a dispersant bonded to their sidewalls are present in a weight range greater than zero and at most about 30% by weight, based on the total weight of the dispersion. Ideally, the weight range of the oxidized discrete carbon nanotubes having a dispersant bonded to their sidewalls in the dispersion is from about 0.01 to about 10% by weight, more ideally from about 0.01 to about 5% by weight, based on the total weight of the dispersion.

[0045] In another embodiment of the invention, the majority of carbon nanotubes present in the dispersion are discrete. Ideally, at least about 51% by weight of the oxidized carbon nanotubes with bound dispersant on their sidewalls are discrete; ideally, at least about 65% by weight of the oxidized carbon nanotubes with bound dispersant on their sidewalls are discrete; more ideally, at least about 75% by weight of the oxidized carbon nanotubes with bound dispersant on their sidewalls are discrete; and most ideally, at least about 85% by weight of the carbon nanotubes are discrete.

[0046] In another embodiment of the invention, the dispersion of the oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes comprises about 0.05% to about 80% of filler relative to the total weight of the dispersion (by weight%). Ideally, the weight percentage of filler relative to the total weight of the dispersion is about 0.05% to about 30%, most ideally about 0.1% to about 10%.

[0047] The filler is selected from the group consisting of carbon black, graphene, graphene oxide, reduced graphene, carbon fiber, silica, silicate, halloysite, clay, calcium carbonate, wollastonite, glass, flame retardant, and talc. The filler can be in the shape of generally spherical particles, rods, fibers, or plates. Ideally, the filler has at least one size range greater than about 1 nm and less than about 10 micrometers, more ideally at least one size range greater than about 5 nm and less than about 2 micrometers, and most ideally at least one size range greater than about 10 nm and less than about 1 micrometer.

[0048] In some embodiments, the dispersion of oxidized discrete carbon nanotubes further comprises a mixture of at least two different fillers. In some embodiments, the dispersion of oxidized discrete carbon nanotubes further comprises a mixture of different types of single fillers, which may vary depending on particle size, thermal conductivity, filler content, or molecular weight.

[0049] In a further embodiment of the invention, the dispersion further comprises a photocrosslinkable monomer, oligomer, or polymer. The crosslinkable monomer, oligomer, or polymer contains molecular units selected from the group consisting of carbon-carbon double bonds, carbon-carbon triple bonds, amine esters, acrylates, alkyl acrylates, cyanonitriles, cyanoacrylates, nitrile, epoxy resins, amides, amines, alcohols, ethers, and esters.

[0050] In another embodiment, the dispersion of oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes further comprises a thermoplastic. The dispersion of oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes may be coated with a thermoplastic, or the oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes may be dispersed within a thermoplastic. Ideal thermoplastics are selected from amorphous and semi-crystalline thermoplastics, including but not limited to polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polycarbonate-acrylonitrile butadiene styrene blends (PC-ABS), polyetherimide (PEI), polystyrene sulfide (PPSF), polyethylene terephthalate (PET), polyethylene terephthalate diol (PETG), polyetheretherketone (PEEK), polyamides (e.g., but not limited to nylon 12, nylon 11, nylon 6, and nylon 6,6), polyvinyl alcohol and its copolymers, polyvinyl butyrate and its copolymers, polyvinylpyrrolidone and its copolymers, and polyethers and their copolymers. Thermoplastics can be linear polymers, graft polymers, comb polymers, or block polymers.

[0051] In yet another embodiment, the dispersion of the oxidized discrete carbon nanotubes having a bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes further includes an elastomer. The elastomer may be selected from, but is not limited to, the group consisting of: natural rubber, polyisobutylene, polybutadiene, styrene-butadiene, hydrogenated styrene-butadiene, butyl rubber, polyisoprene, styrene-isoprene rubber, ethylene propylene diene monomer (EPDM) rubber, silicone resin, polyurethane, polyester, polyether, polyacrylate, hydrogenated and non-hydrogenated nitrile butadiene rubber, halogenated elastomers, polyolefin elastomers, fluorinated elastomers, and combinations thereof. The elastomer may be non-crosslinked or crosslinked, grafted or copolymerized.

[0052] In another embodiment, the dispersion of the oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes further comprises polymer impact modifiers with a glass transition temperature below about 25°C. The impact modifiers are selected from the group consisting of polyethers, polyesters, vinyl polymers, polyethylene copolymers, polyolefin polyacrylates, polyurethanes, polyamides and polysiloxanes, blends thereof, and copolymers thereof. They may be further functionalized with reactive groups (e.g., but not limited to epoxy, hydroxyl, isocyanate, and carboxyl groups).

[0053] Ideally, impact modifiers should be phase-separated from the main matrix material of the dispersion, yet still possess good cohesiveness or thermodynamic interactions. More ideally, the impact modifier should be composed of block copolymers or core-shell polymers. Examples of core-shell polymers include PARALOID™ impact modifiers based on acrylates or butadiene. Even more ideally, the refractive index of the impact modifier should be at least within 0.03 units, and more preferably within 0.02 units, of the matrix refractive index to minimize radiative scattering in the UV-visible wavelength range.

[0054] Core-shell particles may include more than one core and / or more than one shell. Furthermore, a mixture of core-shell particles and elastomer particles may be used. In one embodiment, two impact modifiers of different diameters are used in a certain ratio. Using two different impact modifiers of different diameters has the effect of reducing the viscosity of the liquid radiation-cured resin. In one embodiment, the impact modifier composition is a diameter ratio of about 7:1 (e.g., 140 nm particles to 20 nm particles) and a wt% ratio of about 4:1. In another embodiment, the impact modifier composition is a diameter ratio of about 5:1 and a wt% ratio of about 4:1. In yet another embodiment, the impact modifier composition is a diameter ratio of about 5:1 and a wt% ratio of about 6:1.

[0055] In a dispersion of oxidized discrete carbon nanotubes with a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes, the diameter of the phase-separated domain size of the impact modifier can be greater than about 0.005 μm and less than about 1 μm, with an ideal diameter greater than 0.01 μm and less than about 0.8 μm, and a most ideal diameter greater than about 0.05 μm and less than about 0.6 μm.

[0056] The impact modifier may be present in the dispersion of oxidized discrete carbon nanotubes having a dispersant bound to the sidewalls of the oxidized discrete carbon nanotubes at a concentration of at least about 0.1% by weight to less than about 30% by weight, ideally at least greater than about 0.5% to less than about 15%, and most ideally at least about 2% to less than about 10%.

[0057] In another embodiment, the dispersion of oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes further comprises metal powder. The metal powder may contain any of the metallic elements listed in the periodic table. The metal may also be a metal oxide, metal carbide, metal silicate, or metal nitride, or an alloy with other elements. Ideally, the metal powder may be selected from, but is not limited to, categories such as stainless steel, Inconel, bronze, copper, silver, platinum, tungsten, aluminum, cobalt, and tungsten carbide. More ideally, the metal powder particle diameter is greater than about 1 nm and less than about 20 micrometers. For more efficient sintering, a bimodal metal powder particle diameter distribution is further desirable. Even more ideally, the larger particle size constitutes the majority of the metal powder particle distribution.

[0058] In another embodiment, the dispersion of oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes further comprises ceramic powder. The ceramic powder may be selected from, but is not limited to, alumina, zirconium oxide, silicon dioxide, boron nitride, and silicon carbide, and mixtures thereof. Ideally, the ceramic powder particle diameter is greater than about 1 nm and less than about 20 micrometers. For more efficient sintering of the ceramic, it may be further ideally to have a bimodal ceramic powder particle diameter distribution. Further ideally, the larger particle size constitutes the majority of the ceramic powder particle distribution.

[0059] In another embodiment, the dispersion of the oxidized discrete carbon nanotubes having a bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes further comprises a mixture of ceramic powder and metal powder, which forms a cermet upon sintering. The ideal cermet is based on carbides, nitrides, borides, and silicates from Groups 4 to 6 of the periodic table.

[0060] In another embodiment of the invention, the dispersion of the oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes further comprises at least one additional dispersant attached to the sidewalls of the oxidized discrete carbon nanotubes, said additional dispersant being selected from the group consisting of: anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants, polyvinyl alcohol, copolymers of polyvinyl alcohol and polyvinyl acetate, polyvinylpyrrolidone and copolymers thereof, carboxymethyl cellulose, carboxypropyl cellulose, carboxymethylpropyl cellulose, hydroxyethyl cellulose, polyetherimide, polyether, starch and mixtures thereof. Ideally, non-covalently linked polymeric dispersants are selected from the group consisting of amphiphilic polymers.

[0061] The molecular weight of the additional dispersant attached to the sidewall of the oxidized discrete carbon nanotubes is ideally in the range of about 100 to about 400,000 Daltons, more ideally in the range of about 1,000 to about 200,000 Daltons, and most ideally in the range of about 10,000 to about 100,000 Daltons.

[0062] The additional dispersant attached to the sidewalls of the oxidized discrete carbon nanotubes and the dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes may be present in the dispersion at a weight ratio of about 0.01 to about 2 of the additional dispersant attached to the oxidized discrete carbon nanotubes and the dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes. Ideally, the weight ratio is about 0.1 to about 1, and more ideally about 0.2 to about 0.75.

[0063] Another embodiment of the invention further comprises an organic solvent in which a dispersion of oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes is further comprising a dispersant. A preferred organic solvent is selected from the group consisting of alcohols, ethers, ketones, dioxolane, acetates, glycols, and mixtures thereof.

[0064] In another embodiment of the invention, the dispersion of oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes further comprises water.

[0065] In one embodiment of the invention, the dispersion of oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes is electrostatically dissipative. Ideally, the surface resistivity of the dispersion is less than 10 billion ohms per square meter, more ideally less than 10 million ohms per square meter.

[0066] In yet another embodiment of the invention, the dispersion of the oxidized discrete carbon nanotubes having a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes further comprises about 0.1% by weight to about 20% by weight of nitrogen atoms.

[0067] In one embodiment of the invention, for a dispersion of oxidized discrete carbon nanotubes with bound dispersant in the dispersion being 2.5 × 10⁻⁵ g / ml, the dispersion of oxidized discrete carbon nanotubes with bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes has a UV-Vis absorbance greater than 0.5 absorbance units at 500 nm. Ideally, at the same concentration of oxidized carbon nanotubes and measurement wavelength, it is greater than 0.75 absorbance units, and most ideally, at the same concentration of oxidized carbon nanotubes and measurement wavelength, it is greater than 1 absorbance unit.

[0068] In another embodiment of the invention, the filler may be selected from the group consisting of a charring agent, an expanding agent, and a flame retardant (e.g., but not limited to, organohalides (haloalkanes)) that reacts in the gas phase.

[0069] In one embodiment, the dispersion of the oxidized discrete carbon nanotube having a bound dispersant on the sidewall of the oxidized discrete carbon nanotube comprises a filler selected from the group consisting of thermally conductive materials (e.g., but not limited to metals and metal alloys, boron nitride, alumina, silicon nitride, aluminum nitride, diamond, graphite).

[0070] In another embodiment, the dispersion of the oxidized discrete carbon nanotube having a bound dispersant on the sidewall of the oxidized discrete carbon nanotube comprises a filler selected from magnetic and ferromagnetic materials (e.g., but not limited to those containing nickel atoms, iron atoms, cobalt atoms and their alloys and oxides).

[0071] One embodiment of the invention is a dispersion of oxidized discrete carbon nanotubes with a bound dispersant, the dispersion further comprising magnetic or ferromagnetic particles that provide electromagnetic absorption or shielding at frequencies greater than about 1 MHz, ideally greater than about 1 GHz. A dispersion of oxidized discrete carbon nanotubes with a bound dispersant, further comprising electron-conducting filler particles, is also ideal for shielding radio frequencies.

[0072] In yet another embodiment, a dispersion of oxidized discrete carbon nanotubes, including at least a portion of the crosslinkable portion and a dispersant bonded to at least one sidewall of the oxidized discrete carbon nanotube, is at least partially crosslinked by radiation, and subsequently post-cured by a heat or irradiation method to obtain the final desired component properties, wherein the time required for post-curing to obtain the final desired component properties is 10% less, ideally 25% less, and more ideally 50% less than that for a dispersion without oxidized discrete carbon nanotubes.

[0073] In another embodiment, the dispersion of the oxidized discrete carbon nanotube, including at least a crosslinkable portion and a dispersant bonded to at least one sidewall of the oxidized discrete carbon nanotube, is sprayable.

[0074] In another embodiment, the dispersion of oxidized discrete carbon nanotubes, including at least a portion of the crosslinkable portion and a dispersant bonded to at least one sidewall of the oxidized discrete carbon nanotubes, further includes materials sintered with about 10% lower radiation power than similar dispersions without oxidized discrete carbon nanotubes, ideally about 25% lower radiation power, and more ideally about 50% lower radiation power than similar dispersions without oxidized discrete carbon nanotubes.

[0075] In one embodiment, the dispersion of oxidized discrete carbon nanotubes with a bound dispersant further includes an elastomer, wherein the final component exhibits at least about 20% higher fracture resistance, ideally at least about 50% higher, and most ideally at least about 100% higher fracture resistance under cyclic fatigue than a similar dispersion of oxidized discrete carbon nanotubes without a bound dispersant.

[0076] Other implementation plans

[0077] Implementation Scheme 1. An additive manufacturing dispersion, wherein the dispersion comprises at least a crosslinkable portion and oxidized discrete carbon nanotubes, the oxidized discrete carbon nanotubes having a bound dispersant on at least one sidewall of the oxidized discrete carbon nanotubes, wherein the oxidized discrete carbon nanotubes are present in a range greater than 0 to at most about 30% by weight based on the total weight of the dispersion, and the majority of the carbon nanotubes present in the dispersion are discrete.

[0078] Implementation Scheme 2. The dispersion according to Implementation Scheme 1, wherein the oxidized discrete carbon nanotube includes an inner surface and an outer surface, each surface including an inner surface oxidized substance content and an outer surface oxidized substance content, wherein the inner surface oxidized substance content differs from the outer surface oxidized substance content by at least about 20% and up to 100%.

[0079] Implementation Scheme 3. The dispersion according to Implementation Scheme 1, wherein the oxidized discrete carbon nanotubes comprise a mixture of oxidized discrete carbon nanotubes having a bimodal or trimodal diameter, formed by a combination of oxidized discrete single-walled carbon nanotubes, oxidized discrete double-walled carbon nanotubes, and oxidized discrete multi-walled carbon nanotubes.

[0080] Implementation Scheme 4. The dispersion according to Implementation Scheme 1, wherein the dispersant bonded to the sidewall of the oxidized discrete carbon nanotube is covalently bonded.

[0081] Implementation Scheme 5. The dispersion according to Implementation Scheme 1, wherein the dispersant bound to the sidewall of the oxidized discrete carbon nanotube comprises an average molecular weight in the range of about 50 to about 20,000 Daltons, and the weight fraction of the dispersant bound to the sidewall of the discrete carbon nanotube relative to the oxidized discrete carbon nanotube is greater than about 0.02 and less than about 0.8.

[0082] Implementation Scheme 6. The dispersion according to Implementation Scheme 1, wherein the dispersant bonded to the sidewall of the oxidized discrete carbon nanotube is miscible with the material in contact with the bonded dispersant.

[0083] Implementation Scheme 7. An additively manufactured dispersion, wherein the dispersion comprises at least a portion of a crosslinkable acrylate moiety and an oxidized discrete carbon nanotube, wherein the oxidized discrete carbon nanotube has a dispersant bonded to at least one sidewall of the oxidized discrete carbon nanotube, wherein the dispersant bonded to the sidewall of the discrete carbon nanotube comprises molecular units selected from the group consisting of ethers.

[0084] Implementation Scheme 8. The dispersion according to Implementation Scheme 7, wherein the molecular unit comprises ethylene oxide.

[0085] Implementation Scheme 9. The dispersion according to Implementation Scheme 1 further comprises about 0.1% to about 30% by weight of a filler, said filler being selected from the group consisting of carbon black, graphene, graphene oxide, reduced graphene, carbon fiber, silica, silicates, halloysite, clay, calcium carbonate, wollastonite, glass, flame retardant and talc.

[0086] Implementation Scheme 10. The dispersion according to Implementation Scheme 1 further includes a member of the group consisting of thermoplastic plastics, thermosetting plastics and elastomers.

[0087] Implementation Scheme 11. The dispersion according to Implementation Scheme 1 further comprises a core-shell elastomer, said core-shell elastomer further comprising a particle diameter of about 0.01 to about 1 micrometer.

[0088] Implementation Scheme 12. The dispersion according to Implementation Scheme 1 further comprises semiconductor powder, metal powder and / or ceramic powder having a particle diameter of about 1 nm to about 20 micrometers.

[0089] Implementation Scheme 13. The dispersion according to Implementation Scheme 1 further comprises at least one additional dispersant attached to the sidewall of the oxidized discrete carbon nanotube, said additional dispersant being selected from the group consisting of anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants, polyvinyl alcohol, copolymers of polyvinyl alcohol and polyvinyl acetate, polyvinylpyrrolidone and copolymers thereof, carboxymethyl cellulose, carboxypropyl cellulose, carboxymethylpropyl cellulose, hydroxyethyl cellulose, polyetherimide, polyether, starch and mixtures thereof.

[0090] Implementation Scheme 14. The composition according to Implementation Scheme 1, wherein the oxidized discrete carbon nanotube comprises about 0.1 wt% to about 20 wt% of nitrogen atoms.

[0091] Implementation Scheme 15. An additively manufactured dispersion, wherein the dispersion comprises at least a portion of a thermoplastic portion and discrete carbon nanotubes, wherein the discrete carbon nanotubes have a dispersant bonded to at least one sidewall of the discrete carbon nanotubes, wherein the discrete carbon nanotubes are present in an amount greater than 0 to at most about 30% by weight based on the total weight of the dispersion.

[0092] Implementation Scheme 16. The dispersion according to Implementation Scheme 15, wherein the dispersant bound to the sidewall of the oxidized discrete carbon nanotube is at least partially thermally decomposed in nitrogen at a temperature below about 500°C with an ash content of less than about 5% by weight.

[0093] Implementation Scheme 17. An additive manufacturing dispersion according to Implementation Scheme 15, wherein most of the carbon nanotubes are discrete.

[0094] Implementation Scheme 18. The dispersion according to Implementation Scheme 1, wherein the component prepared by additive manufacturing has a resistance of less than about 10 billion ohms per square.

[0095] Implementation Scheme 19. The dispersion according to Implementation Scheme 1, wherein the concentration of the oxidized discrete carbon nanotubes in the dispersion is 2.5 × 10⁻⁵ g / ml, and the dispersion has a UV-Vis absorption at 500 nm greater than about 0.5 absorbance units.

[0096] Implementation Scheme 20. The dispersion according to Implementation Scheme 1 further comprises a filler selected from the group consisting of thermally conductive materials, such as, but not limited to, metals and metal alloys, boron nitride, alumina, silicon nitride, aluminum nitride, diamond, graphite, and graphene.

[0097] Implementation Scheme 21. An additive manufacturing dispersion for at least partially encapsulating electronic components, wherein the dispersion comprises: At least a portion of the crosslinkable portion; and Oxidized discrete carbon nanotubes; The oxidized discrete carbon nanotubes include a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes; and The oxidized discrete carbon nanotubes are present in a range greater than zero and at most about 30% by weight, based on the total weight of the dispersion; and Most of the carbon nanotubes present in the dispersion are discrete. Implementation

[0098] In the following description, certain details (e.g., specific quantities, dimensions, etc.) are set forth to provide a full understanding of the embodiments disclosed herein. However, it will be apparent to those skilled in the art that the invention can be practiced without such specific details. In many cases, relevant details have been omitted (for such considerations, etc.) because such details are not essential for obtaining a full understanding of the invention and are within the skill level of those skilled in the art.

[0099] While most terms used in this specification are recognizable to those skilled in the art, it should be understood that, where no explicit definition is given, terms should be interpreted as having the meaning currently accepted by those skilled in the art. Where an interpretation of a term would render it meaningless or substantially meaningless, the definition shall be taken from Merriam-Webster, 3rd edition, 2009. Unless specifically stated in this specification or necessary for its validity, definitions and / or interpretations shall not be incorporated from other relevant or unrelated patent applications, patents, or publications.

[0100] In various embodiments, a dispersion is disclosed comprising oxidized discrete carbon nanotubes having a dispersant bound to at least one sidewall of an oxidized discrete carbon nanotube, wherein the oxidized discrete carbon nanotubes are present in an amount greater than 0 to at most about 30% by weight based on the total weight of the dispersion, and most of the carbon nanotubes present in the dispersion are discrete.

[0101] Carbon nanotubes made using metal catalysts (e.g., iron, aluminum, or cobalt) can retain significant amounts of bound or trapped catalyst within the carbon nanotubes, up to 5% by weight or more. These residual metals can be detrimental in applications such as electronic devices due to enhanced corrosion, or can interfere with the vulcanization process in cured elastomeric composites. Furthermore, these divalent or polyvalent metal ions can bind to carboxylic acid groups on the carbon nanotubes and interfere with their dispersion in subsequent dispersion processes. In one embodiment, a dispersion is disclosed comprising oxidized discrete carbon nanotubes having a bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes, the dispersion comprising a residual metal concentration of less than about 50,000 ppm, and ideally less than about 10,000 ppm. The residual catalyst concentration can be conveniently determined using thermogravimetric analysis, which involves heating in nitrogen at 5 °C / min from 25 °C to 800 °C, then switching the gas to air and holding at 800 °C for 30 min. The residual ash percentage is determined by comparing the weight of the remaining material to the weight of the starting material. The metal composition of the ash can then be analyzed using energy-dispersive X-ray diffraction (EDXD) and scanning electron microscopy (SEM). Alternatively, oxidized discrete carbon nanotubes can be separated from the dispersion medium and analyzed using atomic absorption spectrometry (AAS).

[0102] The oxidation level of oxidized discrete carbon nanotubes is defined as the amount (by weight) of oxidized material covalently bonded to the carbon nanotubes. A thermogravimetric analysis method for determining the weight percentage of oxidized material on carbon nanotubes involves taking approximately 5 mg of dried oxidized carbon nanotubes and heating them from room temperature to 800°C at a rate of 5°C / min in a dry nitrogen atmosphere. The percentage of weight loss from 200 to 600°C is taken as the percentage of oxidized material loss. Fourier transform infrared spectroscopy (FTIR) can also be used to quantify the oxidized material, particularly in the wavelength range of 1680 to 1730 cm⁻¹.

[0103] Oxidized carbon nanotubes may contain oxidizing agents including carboxylic acids or carbonyl derivatives. Carbonyl derivatives may include ketones, quaternary ammonium compounds, amides, esters, amide halogens, monovalent metal salts, etc. Alternatively, or furthermore, carbon nanotubes may contain oxidizing agents selected from hydroxyl groups or derived from hydroxyl-containing substances, ketones, and lactones.

[0104] The term "discrete," or "stripped," in this specification refers to individual carbon nanotubes that are substantially separated along their length, i.e., not bundled. Aspect ratio is defined as the ratio of the length to the diameter of a carbon nanotube. If a bundle of carbon nanotubes exists, the aspect ratio is considered to be the ratio of the bundle's length to its diameter. For a spherical object wrapped with carbon nanotubes, the aspect ratio is considered to be 1.

[0105] Depending on the desired application, the aspect ratio of oxidized discrete carbon nanotubes can be unimodal or multimodal (e.g., bimodal or trimodal). A multimodal distribution can have a uniformly distributed range of aspect ratios (e.g., 50% of one L / D range and approximately 50% of another). The distribution can also be asymmetric—meaning a relatively small percentage of discrete nanotubes can have one particular L / D, while a larger number of discrete nanotubes can include a different aspect ratio distribution. The aspect ratio of oxidized discrete carbon nanotubes can be determined, for example, using a dilution of the dispersion in an organic solvent and a scanning electron microscope.

[0106] Manufacturers of carbon nanotubes suitable for use in the applications described in this specification include, for example, Southwest Nanotechnologies, Zeonano or Zeon, CNano Technology, Nanocyl, ACS Materials, American Elements, Chasm Technologies, Haoxin Technology, Hanwha Nanotech Group, Hyperion Catalysis, KH Chemical, Klean Commodities, LG Chem, Nano-C, NTP Shenzhen Nanotech Port, Nikkiso, Raymor, Saratoga Energy, SK Global, Solid Carbon Products, Sigma Aldrich, Sun Nanotech, Thomas Swan, TimesNano, Tokyo Chemical Industry, XF Nano, and OCSiAl.

[0107] One method for obtaining discrete carbon nanotubes involves subjecting them to high mechanical forces. During shearing, the sample may be subjected to intense destructive forces resulting from shearing (turbulence) and / or cavitation, where the processing equipment is capable of generating energy densities up to 10⁶ to 10⁸ joules / m³. Equipment meeting this specification includes, but is not limited to, ultrasonicators, cavitation generators, mechanical homogenizers, pressure homogenizers, and microfluidizers. Such a homogenizer is disclosed in U.S. Patent 756,953, the disclosure of which is incorporated herein by reference. Other shearing equipment includes, but is not limited to, HAAKE™ mixers, Brabender mixers, Omni mixers, Silverson mixers, colloid mills, Gaullin homogenizers, and / or twin-screw extruders. After shearing, the carbon nanotube bundles are loosened, thereby exposing a greater number of nanotube surfaces and / or a larger portion of the nanotube surface to the surrounding environment. Typically, based on a given initial amount of entanglement, the carbon nanotubes produced by this process have a high surface area of ​​oxidized carbon nanotubes, with most, ideally at least about 60%, more ideally at least about 75%, most ideally at least about 95%, and up to 100%. A few tubes, usually very few, remain tightly bound, and the surface of such tightly bound nanotubes is essentially inaccessible.

[0108] In various patent applications (e.g., US2012-0183770A1 and US2011-0294013 A1), Bosnyak et al. prepared discrete carbon nanotubes by intelligently and substantially simultaneously using oxidation and shear forces, thereby oxidizing the inner and outer surfaces of the nanotubes, typically achieving approximately the same level of oxidation on both the inner and outer surfaces, producing single or discrete tubes.

[0109] In many embodiments, this invention differs from earlier applications and disclosures by Bosnyak et al. During the oxidation of carbon nanotubes and the binding of a dispersant to the sidewalls of the oxidized discrete carbon nanotubes, the degree of fibrillation of the carbon nanotubes (which varies depending on the content or type of oxygen-containing material) can affect the number of carbon nanotubes and also the dispersant bound to the sidewalls of the oxidized carbon nanotubes. For example, if many tubes are arranged in a trunk, the tubes within the core of the trunk are less likely to contain oxidized material that reacts with nitric acid compared to the tubes in the outermost part of the trunk. For more homogeneous groups of modified carbon nanotubes, a discrete or open carbon nanotube structure is desirable during the reaction process. For some applications (e.g., but not limited to conductivity in two-phase materials), it may be desirable to control the degree of fibrillation of the carbon nanotube bundle to obtain the distribution of the dispersant bound to the sidewalls of the oxidized discrete carbon nanotubes.

[0110] A dispersion of oxidized discrete carbon nanotubes, including a dispersant bound to the sidewalls of the oxidized discrete carbon nanotubes, can be prepared by first preparing oxidized discrete carbon nanotubes, and then binding a dispersant to the sidewalls or ends of the oxidized discrete carbon nanotubes; or alternatively, preparing oxidized carbon nanotubes, then binding a dispersant to the sidewalls or ends of the oxidized carbon nanotubes, and then discretizing the carbon nanotubes with the bound dispersant.

[0111] While not limited by the chemistry of covalently bonding the dispersant to the carbon nanotubes, it is generally used to react the carboxylic acid groups on the carbon nanotubes with the amine functional groups of the selected dispersant. An example (but not limited to) suitable dispersants is a commercial product from Huntsman Corporation, an amine-terminated polyether, Jeffamine. The ratio of propylene oxide to ethylene oxide and the degree of amination can vary in the Jeffamine series. Alternatively, the hydroxyl groups present on the carbon nanotubes can react with the carboxyl, isocyanate, or glycidyl groups of the selected dispersant. Other useful chemical motifs for covalently bonding molecules to the sidewalls of carbon nanotubes include, but are not limited to, azide, acetic acid, and silane motifs.

[0112] Dispersions of oxidized discrete carbon nanotubes with bound dispersants can be advantageously used in additive manufacturing to improve processability and part properties by employing near-infrared to up to 1 terahertz radio frequency radiation that is rapidly absorbed by the carbon nanotubes to generate heat. This effect can be used to improve the time required for complete curing of crosslinkable molecules, improve the sintering of materials, and reduce part warpage.

[0113] Suitable impact modifiers are elastomers, ideally pre-formed elastomer particles. These elastomers have a glass transition temperature (Tg) below 0°C, ideally below -20°C.

[0114] The particle size of the impact-modified component can be obtained using, for example, a dynamic light scattering nanoparticle size analysis system. An example of such a system is the LB-550 machine available from Horiba Instruments. The ideal method for measuring particle size is laser diffraction particle size analysis according to ISO 13320:2009. Information on such analysis can be found in Setting New Standards for Laser Diffraction Particle Size Analysis, Alan Rawle and Paul Kippax, Laboratory Instrumentation News, January 21, 2010.

[0115] The monomers or solvents of the liquid radiation-cured resin used for analysis can affect the measured average particle size. Furthermore, laser diffraction analysis may require the use of solvents or other low-viscosity dispersants. These solvents can also affect the measured average particle size. For the purposes of this study, the average particle size of the dispersion refers to those particles that have been exposed to the listed monomers of a given formulation, dispersed, and then analyzed using propylene carbonate as the solvent for laser diffraction particle size analysis. For particle size analysis of dispersions of impact modifier particles, a concentration of 0.1–0.4 g of dispersion per 10 g of propylene carbonate is typically used in dilute propylene carbonate solutions.

[0116] Suitable impact modifiers are elastomers based on copolymers of ethylene or propylene with one or more C2 to C12 olefin monomers, which can be mixed into dispersions of oxidized discrete carbon nanotubes with bound dispersants.

[0117] Such examples are ethylene / propylene copolymers or ethylene / propylene copolymers that optionally contain a third copolymerizable diene monomer (EPDM) (e.g., 1,4-hexadiene, dimercyclopentadiene, bicyclooctadiene, methylene norbornene, ethylidene norbornene, and tetrahydroindene); ethylene / α-olefin copolymers, such as ethylene-octene copolymers and ethylene / α-olefin / polyene copolymers.

[0118] Other suitable elastomers are polybutadiene, polyisoprene, styrene / butadiene random copolymers, styrene / isoprene random copolymers, acrylate rubbers (e.g., polybutyl acrylate), poly(hexamethylene carbonate), ethylene / acrylate random copolymers and acrylic block copolymers, styrene / butadiene / (meth)acrylate (SBM) block copolymers, styrene / butadiene block copolymers (styrene-butadiene-styrene block copolymers (SBS), styrene-isoprene-styrene block copolymers (SIS and their hydrogenated forms, SEBS, SEPS) and (SIS), as well as ionomers.

[0119] Suitable commercial elastomers are Kraton (SBS, SEBS, SIS, SEBS and SEPS) block copolymers produced by Shell, Nanostrength block copolymers E20, E40 (SBM type) and M22 (all acrylic) produced by Arkema, Lotryl ethyl / acrylate random copolymers (Arkema) and Surlyn ionomers (Dupont).

[0120] Optionally, the elastomer can be modified to contain reactive groups, such as epoxy, trimethoxy ester, carboxyl, or ethanol groups. This modification can be introduced, for example, through reactive grafting or copolymerization. Commercial examples of modification introduced through copolymerization are Arkema's Lotader random ethylene / acrylate copolymers AX8840 (glycidyl methacrylate / GMA modified), AX8900, and AX8930 (GMA and maleic anhydride modified / MA).

[0121] Optionally, the elastomer can be crosslinked after being mixed into a dispersion of oxidized discrete carbon nanotubes with a binding dispersant. The crosslinked structure can be introduced by conventional methods. Examples of crosslinking agents for such materials include peroxides, sulfur, cresols, etc., optionally combined with multifunctional monomers such as divinylbenzene, ethylene glycol di(meth)acrylate, diallyl maleate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, trimethylolpropane triacrylate, allyl methacrylate, etc.

[0122] In one embodiment, the impact modifier that can be mixed into a dispersion of oxidized discrete carbon nanotubes having a bound dispersant is a pre-formed elastomer particle. The elastomer particle can be prepared by various methods, including those obtained by separation from latex prepared by emulsion polymerization or by in-situ preparation in another component of the composition.

[0123] Suitable commercial sources of such pre-formed elastomer particles are PB (polybutadiene) latex or PBA (polybutyl acrylate) latex with different average particle sizes, which are available from various manufacturers, or latex obtained by emulsifying EPDM, SBS, SIS or any other rubber.

[0124] Optionally, the elastomer may contain a crosslinked structure. The crosslinked structure can be introduced by conventional methods. Examples of crosslinking agents for such materials include peroxides, sulfur, cresols, etc., optionally combined with multifunctional monomers such as divinylbenzene, ethylene glycol di(meth)acrylate, diallyl maleate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, trimethylolpropane triacrylate, allyl methacrylate, etc.

[0125] Optionally, a shell may be present on the particles, which may be introduced, for example, by grafting or during the second stage of emulsion polymerization. Examples of such particles are core-shell impact modifier particles containing a rubber core and a glass shell. Examples of core materials are polybutadiene, polyisoprene, acrylic rubber (e.g., polybutyl acrylate rubber), styrene / butadiene random copolymers, styrene / isoprene random copolymers, or polysiloxanes. Examples of shell materials or graft copolymers are (co)polymers of vinyl aromatic compounds (e.g., styrene) and vinyl cyanides (e.g., acrylonitrile) or (meth)acrylates (e.g., methyl methacrylate).

[0126] Optionally, reactive groups can be introduced into the shell by copolymerization (e.g., copolymerization with glycidyl methacrylate) or by treating the shell to form reactive functional groups. Suitable reactive functional groups include, but are not limited to, epoxy, trimethoxy ester, hydroxy, carboxyl, vinyl ether, and / or acrylate groups.

[0127] Suitable commercially available products of these core-shell elastomer particles are, for example, but not limited to, Resinous Bond RKB (a dispersion of core-shell particles in epoxy resin manufactured by Resinous Chemical Industries, Inc.), Durathrength D400, Durathrength 400R (manufactured by Arkema Group), Paraaloid EXL-2300 (non-functional shell), Paraaloid EXL-2314 (epoxy functional shell), Paraaloid EXL-2600, Paraaloid KM 334, and Paraaloid EXL 2300G. Paraloid core-shell elastomers are manufactured by Dow Chemical Company, Genioperl P53, Genioperl P23, and Genioperl P22 are manufactured by Wacker Chemie, and Kane Ace MX products (manufactured by Kaneka).

[0128] Other examples of such elastomer particles are crosslinked polyorganosiloxane rubbers that may comprise dialkylsiloxane repeating units, wherein "alkyl" is a C1 to C6 alkyl group. Such particles can be prepared by the method disclosed in Block's U.S. Patent No. 4,853,434 (which is incorporated herein by reference in its entirety). The particles can be modified to include reactive groups, such as ethylene oxide, glycidyl, trimethoxy ester, hydroxyl, vinyl ester, vinyl ether, or (meth)acrylate groups, or combinations thereof, ideally on the surface of the particles. An example of commercially available polyorganosiloxane elastomer particles is Albidur.

[0129] EP 2240(A), Albidur EP 2640, Albidur VE 3320, Albidur EP 5340, Albidur EP 5640 and Albiflex 296 (dispersions of particles in epoxy or vinyl ether resins, Hanse Chemie, Germany), Genioperl M41C (dispersions in epoxy resins, Wacker Chemie), Chemisnow MX series and MP series (Soken Chemical and Engineering). Other materials that can be used to manufacture core-shell particles for use in this invention can be found, for example, in Nakamura et al., J Appl. Polym. Sci. v 33 n 3 Feb. 20, 1987, pp. 885-897, 1987, which discloses core-shell materials having a poly(butyl acrylate) core and a poly(methyl methacrylate) shell. The shell is treated to contain epoxy groups; Saija, LM and Uminski, M., Surface Coatings International Part B 2002 85, No. B2, June 2002, pp. 149-53, describes a core-shell material having a core and shell prepared from poly(methyl methacrylate-butyl acrylate copolymer), and treated with MMA or AMPS to produce a material with carboxylic acid groups on the surface; Aerdts, A. M. et al., Polymer 1997 38, No. 16, 1997, pp. 4247-52, describes a material using polystyrene, poly(methyl methacrylate), or polybutadiene as its core. Epoxidized poly(methyl methacrylate) is used for the shell. Epoxide sites are reaction sites on the shell of this material. In another embodiment, glycidyl methacrylate and methyl methacrylate are used as comonomers in the shell.

[0130] Core-shell particles may include more than one core and / or more than one shell. Furthermore, mixtures of core-shell particles and elastomer particles can be used. Two impact modifiers of different diameters can be used in a certain ratio to reduce the viscosity of dispersions comprising crosslinkable monomers or oligomers. For example, the impact modifier composition may be approximately a 7:1 diameter ratio (i.e., 140 nm diameter particles to 20 nm diameter particles) and a 4:1 wt% ratio.

[0131] Another desirable characteristic for selecting elastomers or impact modifiers is choosing a composition whose refractive index is at least within 0.03 units, and more ideally within 0.02 units, of the refractive index of the material in which it is dispersed, in order to minimize radiation scattering in the UV-visible wavelength range. An example of such a mixture is Paraaloid KM 334, with a refractive index of 1.47, and Dymax BR-952-a urea-dimethacrylate, with a refractive index of 1.48.

[0132] The dispersion of oxidized discrete carbon nanotubes with a bound dispersant further comprises, by weight, about 0.1% to about 30% of a filler selected from the group consisting of carbon black, graphene, graphene oxide, reduced graphene, carbon fibers, silica, silicates, halloysite, clay, calcium carbonate, wollastonite, glass, flame retardants, and talc. The filler may also be surface modified to improve its bonding and distribution within the dispersion. One example of surface treatment is the use of a silane coupling agent on silica particles.

[0133] A general method for determining the thermal conductivity of a dispersion is to apply a known heat flux to the sample, and once the steady-state temperature of the sample is reached, measure the temperature difference across the sample thickness. After assuming one-dimensional heat flux and an isotropic medium, Fourier's law is then used to calculate the measured thermal conductivity.

[0134] [Example] [1–] [Oxidation] [Tuball, TM , (OCSiAl) ] In a 1-liter glass reactor equipped with a stirrer and condenser, 500 g of 67% by weight nitric acid was heated to 95°C. 5 g of unprocessed single-walled carbon nanotubes (Tuball™) were added to the acid. The unprocessed, fluffy carbon nanotubes have a tightly bound trunk-like morphology, ranging in length from a few millimeters to a diameter of one millimeter. The mixture of acid and carbon nanotubes was stirred while the solution was maintained at approximately 95°C for 5 hours. At the end of the reaction period, the oxidized single-walled carbon nanotubes were filtered to remove the acid and washed with reverse osmosis (RO) water until the pH reached 3–4. The resulting CNTs were oxidized to approximately 3.6% and contained 4.4% metal residue.

[0135] [Example] [2–] [Oxide multi-walled carbon nanotubes] [CNano Flotube 9000] Four liters of concentrated nitric acid containing 65% nitric acid were added to a 10-liter temperature-controlled reaction vessel equipped with an ultrasonic transducer and stirrer. Forty grams of non-discrete multi-walled carbon nanotubes (Flowtube 9000 class from CNano) were added to the reaction vessel while the acidic mixture was stirred, and the temperature was maintained at 85°C. The ultrasonic transducer power was set to 130-150 watts, and the reaction was continued for 3 hours. After 3 hours, the viscous solution was transferred to a sieving process with a 5-micron filter screen, and most of the acidic mixture was removed by filtration at 100 psi. The filter cake was washed once with 4 liters of deionized water, followed by once with 4 liters of ammonium hydroxide solution with a pH greater than 9, and then twice more with 4 liters of deionized water. The final pH of the washed solution was 4.5. Small samples of the filter cake were vacuum-dried at 100°C for 4 hours and subjected to thermogravimetric analysis as previously described. The amount of oxidized material on the fibers was 2.4% by weight, and the average aspect ratio was 60 as determined by scanning electron microscopy. The residual catalyst content was determined to be 2,500 ppm.

[0136] [Example] [3–] [The dispersant is covalently attached to the oxidized single-walled carbon nanotubes]. Oxidized single-walled carbon nanotubes in wet cake form with a water content of 6.6% by weight, from Example 1, were used. 30.3 g of the wet cake was mixed with 30 g of isopropanol, and then 3 g of Jeffamine M2005 monoamine-terminated polyether dissolved in 350 g of isopropanol and 622 g of water was added with stirring. Stirring was continued for 10 minutes. The slurry was then transferred to a Waring mixer and mixed at high speed for 10 minutes. The slurry was then passed through a laboratory-scale homogenizer, kept at a temperature below 45°C, until no large structures with a size >20 micrometers could be observed under an optical microscope. The resulting mixture was then filtered through a Buchner sieve and No. 2 Whatman filter paper at 13°C and washed four times with a 100 cm³ 335 wt% isopropanol aqueous solution. The washed wet filter cake was then first dried in a convection oven at 120°C to 95% solids, and then dried in a vacuum oven at 150°C for 1 hour. This is referred to as SWNT MB in Table 3. TGA analysis conducted in nitrogen at a rate of 5 °C / min within the range of 200–600 °C yielded a 47% covalently bonded polyether.

[0137] [Example] [4–] [The dispersant was covalently attached to the oxidized multi-walled carbon nanotubes]. Oxidized multi-walled carbon nanotubes in wet cake form with a water content of 5% by weight, from Example 2, were used. 40 g of the wet cake was mixed with 30 g of isopropanol, and then 2 g of Jeffamine M2005 monoamine-terminated polyether dissolved in 350 g of isopropanol and 622 g of water was added while stirring. Stirring was continued for 10 minutes. The slurry was then transferred to a Waring mixer and mixed at high speed for 10 minutes. The slurry was then passed through a laboratory-scale homogenizer, kept at a temperature below 45°C, until no large structures with a size >20 micrometers could be observed under an optical microscope. The resulting mixture was then filtered through a Buchner sieve and No. 2 Whatman filter paper at 13°C and washed four times with 100 cm³ of 335 wt% isopropanol aqueous solution. The washed wet filter cake was then first dried in a convection oven at 120°C to 95% solids, and then dried in a vacuum oven at 150°C for 1 hour. TGA analysis performed in nitrogen at 5 °C / min in the range of 200–600 °C yielded 18% covalently bonded polyether.

[0138] [Example] [5–] [Coated with nylon powder] [] Nylon 11 was ground into small powder particles with a diameter of less than 10 micrometers. A dispersion was prepared by adding 1 g of the carbon nanotubes from Example 4 and 1 g of polyvinylpyrrolidone (Sigma Aldrich) with a molecular weight of approximately 24,000 Daltons to 200 g of an isopropanol aqueous solution (50 / 50). 100 g of nylon 11 powder was stirred into the modified carbon nanotube dispersion and stirred for 1 hour. The material was then dried in a convection oven at 110°C. The dried material was placed in a ball mill for 1 hour to obtain a fine dispersion of nylon 11 with a dried dispersion coating. The powder can then be used in SLS additive manufacturing processes to produce robust parts with enhanced conductivity and a resistance of less than 10 billion ohms per square meter. Coating of oxidized discrete carbon nanotubes with covalently linked dispersants allows for improved post-sintering annealing of the parts via infrared or radio frequency radiation.

[0139] [Example] [6–] [Coated ceramic powder] [] Alumina powder particles with a diameter of less than 10 micrometers were used. A dispersion was prepared by adding 1 g of the carbon nanotubes from Example 4 along with 1 g of Sigma Aldrich (with a molecular weight of approximately 24,000 Daltons) to 200 g of isopropanol and mixing at 2000 rpm for 5 minutes in a Thinky mixer. The dispersion was selectively sprayed onto a layer of alumina powder, and the alcohol was removed by drying. The powder is combined with a dry dispersion of oxidized discrete carbon nanotubes, which can then be sintered to produce robust parts. The dispersion of oxidized discrete carbon nanotubes with covalently bonded dispersants significantly improves the green strength of ceramic parts, and the covalently bonded dispersants are removed during sintering. Oxidized discrete carbon nanotubes can be used to induce heating via electric / magnetic fields, or infrared or radio frequency radiation.

[0140] [Example] [7–] [Mixed radiation-cured resin] [] Radiation-cured compositions for trough photopolymerization were prepared by weighing the components and placing them into containers. The mixture was mechanically stirred at room temperature or high temperature (up to 80°C) until a homogeneous resin mixture was obtained. The prepared compositions were treated in a trough photopolymerization apparatus, and the manufactured samples were analyzed according to the test methods described below. []

[0141] Manufacturing three-dimensional samples [] The general procedure for preparing three-dimensional samples using a tank-type photopolymerization apparatus is as follows: Radiation-curable resin is poured into the tank. Manufacturing parameters are set to standard black resin and a layer thickness of 25 μm. In this manner, the resin is heated to 31°C before fabrication. Depending on the resin composition, sufficient laser passes are used to provide the required polymerization energy. The material is exposed to a laser emitted in the 405 nm range. Initially, a "green part" is formed in which the middle layer is not fully cured. This under-curing allows subsequent successive layers to adhere better through bonding when further cured. The fabricated "green part" is removed from the machine, washed with isopropanol, air-dried, and post-cured in a curing chamber equipped with a 405 nm multi-directional LED lamp. Unless otherwise specified, all samples are post-cured in the curing chamber at room temperature for 30 minutes. []

[0142] Test methods Resins were prepared to meet desired viscosity and wetting behavior requirements. Viscosity and wetting behavior directly affect recoating depth (layer thickness before radiation exposure), which in turn affects build resolution in the z-direction. Viscosity data of freshly prepared resins were collected using an HR20 Discovery Mixture Rheometer (TA Instrument). A 40 mm 2.002° stainless steel Peltier plate was used for flow scanning experiments. Logarithmic scans were performed by scanning at shear rates from 1.0e⁻³ to 8000 l / s at room temperature. Additional flow temperature ramp tests were performed by increasing the temperature from 25°C to 80°C at a shear rate of 6 l / s and a heating rate of 2°C / min. Table 1 shows the viscosity of the three example compositions at zero shear rate. The data show that viscosity increases exponentially with increasing content of oxidized discrete carbon nanotubes with bound dispersants in the final resin formulation. Table 2 shows the temperature ramp results and provides comparison points at 25°C, 50°C, and 80°C. The results show that viscosity decreases exponentially at a constant shear rate with increasing temperature.

[0143] Table 1 [Example] [25℃] [Viscosity below] [,[cP]] 7.1 2,093 7.2 14,084 Comparison 1 2,284 Table 2 [Example] [25℃] [Viscosity below] [,[cP]] [50℃] [Viscosity below] [,[cP]] [80℃] [Viscosity below] [,[cP]] 7.1 770 161 63 7.2 778 219 105 Comparison 1 2073 267 50 [] Table 3 lists the components of each photocurable composition labeled Examples 7.1, 7.2, and Control 7.1. Note: The amounts of TPO and OB are not included in the total composition percentage. Table 3 [Components] [Example] [7.1] [:] [[] [weight] [%]] [Example] [7.2] [:] [[] [weight] [%]] [Comparison] [1] [[] [weight] [%]] BR-952 47.00 37.00 67.00 BR-371 7.00 7.00 7.00 HEMA 26.00 26.00 26.00 TPO 1.00 1.00 1.00 OB 0.00 0.00 0.06 SWCNT MB 20.00 30.00 0 Tensile data were collected by testing Type IV tensile specimens (ASTM D638) manufactured using a tank photopolymerization apparatus. All specimens were fabricated vertically. Tensile strength, Young's modulus, and elongation at break tests were performed 24 hours or more after post-curing. Tensile tests were performed according to ASTM D638, which is incorporated herein by reference in its entirety except where no measures were taken to control room temperature and humidity, and the bars were not equilibrated within 2 days. Tests were performed on an Instron testing machine (model 5985). The reported data are the average of three measurements. Table 3 shows the ultimate tensile strength, yield strength, and Young's modulus of Examples 7.1 and 7.2 compared to a control without the addition of oxidized discrete carbon nanotubes with a bound dispersant to the composition. These examples demonstrate that the addition of oxidized discrete carbon nanotubes with a bound dispersant increases tensile strength, yield strength, and Young's modulus compared to resins without oxidized discrete carbon nanotubes. Table 4 [Example] [Tensile strength,] [[MPa]] [Yield Strength] [[MPa]] Young's modulus [[GPa]] 7.1 69±0.1 53.0±1.5 2.9±0.05 7.2 67±0.4 48.6±0.6 2.8±0.04 Comparison 1 63.7±1 34.7±0.8 2.1±0.03 [] The cured specimens used for determining Izod impact strength were prepared in the same manner as the tensile test bars, except that the specimens were designed according to ASTM D-256A and had dimensions of 3.2 mm × 12.7 mm × 63.5 mm (thickness × width × length). The specimens were notched using an electric notch cutter from Ray-Ran. Izod impact was measured using a Ray-Ran universal pendulum impact system equipped with a 2.75 J pendulum. The reported data is the average of three measurements. Table 4 shows the impact strength of Examples 7.1 to 7.4. These examples demonstrate that the addition of discrete oxidized carbon nanotubes with a bound dispersant significantly improves the impact strength of the manufactured samples compared to resins with unoxidized discrete carbon nanotubes. [] Table 5 [Example] [Average Impact] [[J / m]] [%] [Increase] 7.1 19.8 32 7.2 15.7 4 7.3 19.8 75 7.4 28.5 151 Comparison 1 15.0 ** Comparison 2 11.3 ** Table 6 lists the components of each photocurable composition labeled Examples 7.3, 7.4 and Control 2. Table 6 [Components] [Example] [7.3] [,] [[] [weight] [%]] [Example] [7.4] [,] [[] [weight] [%]] [Comparison] [2] [,] [[] [weight] [%]] Formlabs Clear 99.95 99.80 100.00 MWCNT 0.05 0.20 0.00 []

[0144] Cross-references to related applications This invention is a continuation-in-part of U.S. Serial No. 17 / 187,658, filed February 26, 2021. U.S. Serial No. 17 / 187,658 itself is a continuation-in-part of U.S. Serial No. 16 / 012,265 (now U.S. Patent No. 10,934,447), filed June 19, 2018. U.S. Serial No. 16 / 012,265 is a continuation-in-part of U.S. Serial No. 15 / 288,553 (now U.S. Patent No. 9,636,649), filed October 7, 2016. U.S. Serial No. 15 / 288,553 is a continuation-in-part of U.S. Serial No. 15 / 225,215, filed August 1, 2016, granted September 12, 2016, and published as U.S. Patent No. 9,493,626. U.S. Serial No. 15 / 225,215 was filed May 27, 2016. And as a continuation-into-part of U.S. Serial No. 15 / 166,931, filed on October 27, 2015, as a continuation of U.S. Serial No. 14 / 924,246, filed on October 27, 2015, as a continuation of U.S. Serial No. 9,353,240, which in turn is a continuation of U.S. Serial No. 13 / 993,206, filed on June 11, 2013, as a continuation of U.S. Serial No. 9,212,273, which claims priority to PCT / EP 2011 / 072427, filed on December 12, 2011, which in turn claims a benefit to U.S. Provisional Application 61 / 423,033, filed on December 14, 2010. All of the foregoing U.S. applications and / or granted patents are expressly incorporated herein by reference. This invention also relates to U.S. Serial Nos. 62 / 319,599; 14 / 585,730; 14 / 628,248; and 14 / 963,845.

Claims

1. An additive manufacturing dispersion, characterized in that the dispersion comprises at least a crosslinkable portion and oxidized discrete carbon nanotubes, the oxidized discrete carbon nanotubes having a dispersant bonded to at least one sidewall of the oxidized discrete carbon nanotubes, wherein the oxidized discrete carbon nanotubes are present in a range greater than 0 to at most about 30% by weight based on the total weight of the dispersion, and most of the carbon nanotubes present in the dispersion are discrete, wherein... The dispersant in this combination is covalently bonded, and wherein the dispersant in this combination comprises ethylene oxide molecular units, or a mixture of propylene oxide and ethylene oxide molecular units.

2. The dispersion as described in claim 1, wherein, The oxidized discrete carbon nanotube includes an inner surface and an outer surface, each surface including an inner surface oxidized material content and an outer surface oxidized material content, wherein the inner surface oxidized material content differs from the outer surface oxidized material content by at least about 20% and up to 100%.

3. The dispersion as described in claim 1, wherein, The oxidized discrete carbon nanotubes include a mixture of oxidized discrete carbon nanotubes with bimodal or trimodal diameters, formed by combining oxidized discrete single-walled carbon nanotubes, oxidized discrete double-walled carbon nanotubes, and oxidized discrete multi-walled carbon nanotubes.

4. The dispersion as described in claim 1, wherein, The dispersant bound to the sidewall of the oxidized discrete carbon nanotube comprises an average molecular weight in the range of about 50 to about 20,000 Daltons, and the weight fraction of the dispersant bound to the sidewall of the discrete carbon nanotube relative to the oxidized discrete carbon nanotube is greater than about 0.02 and less than about 0.

8.

5. The dispersion as described in claim 1, wherein, The dispersant bonded to the sidewall of the oxidized discrete carbon nanotube is miscible with the material in contact with the bonded dispersant.

6. The dispersion as described in claim 1, wherein, The dispersion further comprises about 0.1% to about 30% by weight of a filler selected from the group consisting of carbon black, graphene, graphene oxide, reduced graphene, carbon fiber, silica, silicates, halloysite, clay, calcium carbonate, wollastonite, glass, flame retardant and talc.

7. The dispersion as described in claim 1, wherein, It further includes members of the group consisting of thermoplastics, thermosettings and elastomers.

8. The dispersion as described in claim 1, wherein, It further includes a core-shell elastomer, which further includes a particle diameter of about 0.01 to about 1 micrometer.

9. The dispersion as described in claim 1, wherein, Further including semiconductor powders, metal powders and / or ceramic powders having a particle diameter of about 1 nm to about 20 micrometers.

10. The dispersion as described in claim 1, wherein, It further includes at least one additional dispersant attached to the sidewall of the oxidized discrete carbon nanotube, the additional dispersant being selected from the group consisting of anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants, polyvinyl alcohol, copolymers of polyvinyl alcohol and polyvinyl acetate, polyvinylpyrrolidone and copolymers thereof, carboxymethyl cellulose, carboxypropyl cellulose, carboxymethylpropyl cellulose, hydroxyethyl cellulose, polyetherimide, polyether, starch and mixtures thereof.

11. The dispersion as described in claim 1, wherein, The oxidized discrete carbon nanotubes comprise approximately 0.1% to approximately 20% nitrogen atoms.

12. The dispersion as described in claim 1, wherein, Components manufactured by additive manufacturing have a resistance of less than 10 billion ohms per square meter.

13. The dispersion as described in claim 1, wherein, The concentration of oxidized discrete carbon nanotubes in the dispersion is 2.5 × 10⁻⁵ g / ml, and the UV-Vis absorption of the dispersion at 500 nm is greater than about 0.5 absorbance units.

14. The dispersion as described in claim 1, wherein, It further includes fillers selected from the group consisting of thermally conductive materials, such as, but not limited to, metals and metal alloys, boron nitride, aluminum oxide, silicon nitride, aluminum nitride, diamond, graphite, and graphene.

15. The dispersion as described in claim 1, wherein, Further, it includes bioactive substances selected from the group consisting of substances that can interact with bacteria, viruses, fungi, and biological agents.

16. An additively manufactured dispersion, characterized in that the dispersion comprises at least a portion of a crosslinkable acrylate moiety and an oxidized discrete carbon nanotube, the oxidized discrete carbon nanotube having a bound dispersant on at least one sidewall of the oxidized discrete carbon nanotube, wherein the bound dispersant on the sidewall of the discrete carbon nanotube comprises molecular units selected from the group consisting of ethers, wherein the molecular units comprise ethylene oxide, or a mixture of propylene oxide and ethylene oxide.

17. An additively manufactured dispersion, characterized in that the dispersion comprises at least a thermoplastic portion and discrete carbon nanotubes, the discrete carbon nanotubes having a bound dispersant on at least one sidewall of the discrete carbon nanotubes, wherein the discrete carbon nanotubes are present in an amount greater than 0 to at most about 30% by weight based on the total weight of the dispersion, wherein the bound dispersant on the sidewall of the discrete carbon nanotubes comprises ethylene oxide molecular units, or a mixture of propylene oxide and ethylene oxide molecular units.

18. The dispersion as described in claim 17, wherein, The dispersant bonded to the sidewall of the discrete carbon nanotube undergoes at least partial thermal decomposition in nitrogen at temperatures below approximately 500°C with an ash content of less than approximately 5% by weight.

19. The dispersion as described in claim 17, wherein, Most carbon nanotubes are discrete.

20. An additive manufacturing dispersion for at least partially encapsulating electronic components, characterized in that the dispersion comprises: At least a portion of the crosslinkable portion; The oxidized discrete carbon nanotubes include a dispersant bonded to the sidewalls of the oxidized discrete carbon nanotubes; and the oxidized discrete carbon nanotubes are present in a range greater than zero and up to about 30% by weight based on the total weight of the dispersion; and the majority of the carbon nanotubes present in the dispersion are discrete, wherein the dispersant bonded to the sidewalls of the discrete carbon nanotubes comprises ethylene oxide molecular units, or a mixture of propylene oxide and ethylene oxide molecular units.