TW202244202A - Dispersions for additive manufacturing comprising discrete carbon nanotubes - Google Patents

Abstract

The present invention is directed to additive manufacturing compositions and methods for producing additive manufacturing composite blends with oxidized discrete carbon nanotubes with dispersion agents bonded to at least one sidewall of the oxidized discrete carbon nanotubes. Such compositions are especially useful when radiation cured, sintered or melt fused.

Description

Dispersions for additive manufacturing comprising discrete carbon nanotubes

The present invention relates to additively manufactured compositions and methods of producing additively manufactured composite material blends having oxidized discrete carbon nanotubes having bonded to A dispersant on at least one sidewall of the oxidized discrete carbon nanotubes. Such compositions are especially useful when radiation cured, sintered or melted.

Additive manufacturing (AM) is an appropriate name to describe the technique of building 3D solids by adding layer after layer of material, usually cross-linkable monomers or oligomers, polymers, metals, ceramics and biocompatible material. AM techniques typically use computers, 3D modeling software (computer-aided design, or CAD), machines, and layered materials. Once the CAD sketch is generated, the AM device reads the data from the CAD file and places or adds successive layers of liquid, powder, sheet material or other (e.g. tape) layers in a layer-by-layer manner to create a 3D solid. The term AM encompasses a number of technologies, including subsets such as 3D printing, rapid prototyping (RP), direct digital manufacturing (DDM), layered manufacturing, and additive manufacturing.

Liquid radiation-curable resins are selectively crosslinked (or cured) by an energy source, such as a laser. Efforts in photocurable resin formulations have focused on enhancements in mechanical properties that mimic those of commodity plastics and engineering polymers. Improving the mechanical properties of photocurable resins can be achieved by developing special monomers and curing agents, changing the chain growth mechanism, using hybrid polymerization methods, and adding additives and fillers. However, there are still many limitations due to the balance of their properties such as heat deformation resistance, rigidity, and impact strength.

Addition of 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 fabricated by channel photopolymerization, but generally have much longer undesired cure times. Additionally, these fillers often result in high initial resin viscosity, poor viscosity stability, and exhibit a tendency for the filler to separate from the base resin. There remains a need for fillers that do not introduce undesired additional cure time to the base crosslinkable resin formulation.

Therefore, there is a need for radiation curable resins that produce parts with enhanced mechanical, thermal, electrical, magnetic and chemical properties and meet stringent polymeric resin requirements such as high cure rate, low viscosity, excellent stability and High green strength. In particular, achieving a resistance of at least 10 billion ohms per square with conductive carbon blacks is a challenge due to the aforementioned cure rate requirements.

For AM methods using materials in powder form (metals, ceramics or polymers) there is a need to improve their sinterability as well as their green strength before secondary processing. Adhesive selection is considered critical to successful part fabrication. First, the adhesive must be sprayable. The ideal binder has low viscosity, is stable under shear stress, has good interaction with powdered raw materials, has clean burnout, and has a long shelf life. Common liquid adhesives are butyral resins, polyvinyl compounds, polysiloxanes, polyacrylic acids, and polyether polyurethanes. In some cases, higher strength polymeric binders are required, especially if sintering is performed at higher temperatures.

Binders for metal and ceramic powders are usually 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 packed powder bed, thus improving sinterability, increasing part density, and reducing shrinkage. As the nanoparticle size decreases, the melting point of the nanoparticles decreases exponentially. As a result, the nanoparticles in the binder will sinter at a lower temperature than the raw powder and can fuse the larger particles, improving the green strength of the component. There is a need for binders with low ash residue content at the sintering or curing temperatures of metals, cermats or ceramics.

Binders for polymer powders usually consist of solvents or solvent mixtures that promote swelling of the polymer feedstock, leading to particle agglomeration through interdiffusion and entanglement. Solutions of film-forming polymer dispersions can also be used as binders. Handling of hydrophilic powders such as starch, gypsum and cement requires water-based binders. Hydrophobic polymer powders such as polylactic acid or PLA can be treated with organic solvents. These types of binders for polymer powders can also be used to coat thermoplastic filaments for fusion into parts.

Carbon nanotubes can be classified into single-wall, double-wall and multi-wall according to the number of walls in the tube. Each wall of carbon nanotubes can be further classified as chiral or achiral. Some carbon atoms of carbon nanotubes may be replaced by nitrogen atoms. Carbon nanotubes are currently fabricated as agglomerated carbon nanotube spheres or carbon nanotube bundles, which have very limited commercial use. The use of carbon nanotubes as reinforcing agents in polymer composites is an area where carbon nanotubes are predicted to have significant utility. However, the use of carbon nanotubes in these applications has been hampered by the general inability to reliably produce individualized carbon nanotubes. To realize the full performance-enhancing potential of carbon nanotubes as composites in polymers, the aspect ratio (ie, 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 bundle of carbon nanotubes in a composite is the average length of the bundle divided by the diameter of the bundle.

Various methods have been developed to unravel or disentangle carbon nanotubes in solution. For example, carbon nanotubes can be greatly shortened by aggressive oxidation methods and then dispersed as individual nanotubes in dilute solutions. These tubes have a low aspect ratio unsuitable for high strength composites. Carbon nanotubes can also be dispersed as individuals in very dilute solutions by sonication in the presence of surfactants. Exemplary surfactants for dispersing carbon nanotubes in an aqueous solution include, for example, sodium lauryl sulfate or cetyltrimethylammonium bromide. In some cases, solutions of individualized carbon nanotubes can be prepared from polymer-wrapped carbon nanotubes. Individualized SWNT solutions have also been prepared in very dilute solutions using polysaccharides, polypeptides, water-soluble polymers, nucleic acids, DNA, polynucleotides, polyimides, and polyvinylpyrrolidone, but these Dilute solutions are not suitable for additive manufacturing.

The present invention relates to novel compositions and methods for producing additively manufactured dispersions and parts thereof.

In one embodiment, the composition of the present invention comprises an additively manufactured dispersion, wherein said dispersion comprises at least a portion of crosslinkable partially oxidized discrete carbon nanotubes, said oxidized discrete carbon nanotubes in said The oxidized discrete carbon nanotubes have a dispersant bound on at least one sidewall thereof, wherein the oxidized discrete carbon nanotubes are present in a range of greater than 0 up to about 30 weight percent based on the total weight of the dispersion, and the Most of the carbon nanotubes present in the dispersion are discrete.

Ideally, the oxidized discrete carbon nanotubes comprise an inner surface and an outer surface, each surface comprising an oxidized species content of the inner surface and an oxidized species content of the outer surface, wherein the inner surface oxidized species content is the same as the outer surface oxidized species content The contents vary by at least about 20%, and up to 100%.

The oxidized discrete carbon nanotubes may include a mixture of oxidized discrete carbon nanotubes having a composition consisting of oxidized discrete single-walled carbon nanotubes, oxidized discrete double-walled carbon nanotubes, and oxidized discrete multi-walled carbon nanotubes. Combinations of nanotubes are formed, with a bimodal or trimodal distribution of oxidized discrete carbon nanotube diameters.

The bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is ideally covalently bound.

The bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes desirably comprises an average molecular weight in the range of about 50 to about 20,000 Daltons, and the bound dispersant on the sidewalls of the discrete carbon nanotubes is relative to the oxidized discrete carbon nanotubes The weight fraction of rice tubes is greater than about 0.02 and less than about 0.8.

The bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is ideally miscible with the material of the contact bound dispersant.

A second embodiment of the present invention is an additively manufactured dispersion, wherein the dispersion comprises at least a portion of a crosslinkable acrylate moiety and oxidized discrete carbon nanotubes on at least one sidewall of the oxidized discrete carbon nanotubes has a bound dispersant on the sidewalls of the discrete carbon nanotubes, wherein the bound dispersant on the sidewalls of the discrete carbon nanotubes comprises molecular units selected from the group of ethers.

The molecular units of the second embodiment desirably comprise ethylene oxide.

The first or second embodiment may further comprise from about 0.1% to about 30% by weight of the dispersion (in % by weight) of a filler, ideally wherein the filler is selected from the group consisting of carbon black, graphene, graphene oxide, reduced graphite group consisting of alkenes, carbon fibers, silica, silicates, halloysite, clay, calcium carbonate, wollastonite, glass, flame retardants, and talc.

The first or second embodiment may further comprise members of the group consisting of thermoplastics, thermosets and elastomers.

The first or second embodiment may further comprise a core-shell elastomer, wherein the elastomer desirably comprises particles having a diameter of about 0.01 to about 1 micron.

The first or second embodiment may further comprise a semiconductor powder, a metal powder or a ceramic powder, wherein the powder comprises a particle diameter of about 1 nm to about 20 microns.

The first or second embodiment may further comprise at least one additional dispersant attached to the sidewalls of the oxidized discrete carbon nanotubes, said additional dispersant selected from the group consisting of anionic surfactants, cationic surfactants, nonionic surfactants Agents and zwitterionic surfactants, polyvinyl alcohol, copolymers of polyvinyl alcohol and polyvinyl acetate, polyvinylpyrrolidone and its copolymers, carboxymethylcellulose, carboxypropylcellulose, carboxymethylpropylcellulose , hydroxyethylcellulose, polyetherimide, polyether, starch and mixtures thereof.

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

In a third embodiment of the present invention is an additively manufactured dispersion, wherein the dispersion comprises at least a portion of a thermoplastic portion and discrete carbon nanotubes having a dispersant bound on at least one sidewall of the discrete carbon nanotubes, wherein The discrete carbon nanotubes are present in an amount greater than 0 up to about 30 weight percent based on the total weight of the dispersion.

A third embodiment may include an bound dispersant on the sidewalls of oxidized discrete carbon nanotubes that at least partially thermally decomposes at an ash content of less than about 5% by weight in nitrogen at less than about 500°C.

A third embodiment may include a plurality of discrete carbon nanotubes.

Any of the three embodiments may include a component made by additive manufacturing having a resistance of less than about 10 billion ohms per square.

Any of the three embodiments may include a dispersion having a UV-visible absorbance at 500 nm greater than About 0.5 absorbance units.

Any of the three embodiments may further comprise a group 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. filler.

Any of the three embodiments may further comprise a biologically active substance selected from the group consisting of substances that can interact with bacteria, viruses, fungi and biological agents.

Oxidized carbon nanotubes are those that have been subjected to oxidizing media such as but not limited to concentrated nitric acid, peroxides, and persulfates that introduce chemical units such as carboxylic acids, hydroxyl groups, ketones and lactones. The 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.

Oxidized discrete carbon nanotubes can also include inner and outer surfaces, each surface including the oxidized species content of the inner surface (also referred to as the inner oxygen species content, since the inner oxygen species may be different from the outer oxygen species) and the outer surface Oxygenated species content (also called outer oxygenated species content, since inner oxygen species may be different from outer oxygen species), wherein the inner surface oxidized species content differs from the outer surface oxidized species 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 content of the inner surface oxidized substance can be up to 3% by weight relative to the weight of the carbon nanotubes, ideally about 0.01 to about 3% by weight relative to the weight of the carbon nanotubes, more preferably about 0.01 to about 2%, and most ideally from about 0.01 to about 1. A particularly desirable content of oxidized substances on the inner surface is 0 to about 0.01% by weight relative to the weight of the carbon nanotubes. The content of the substance oxidized on the outer surface may be about 0.1 to about 65% by weight relative to the weight of the carbon nanotubes, ideally about 1 to about 40% by weight, and more ideally about 1 to about 20% by weight. This is determined by comparing the externally oxidized species content of a given majority of nanotubes to the total weight of that majority of nanotubes.

The oxidized discrete carbon nanotubes may further comprise a mixture of oxidized discrete carbon nanotubes consisting of oxidized discrete single-walled carbon nanotubes, oxidized discrete double-walled carbon nanotubes, and oxidized discrete multi-walled carbon nanotubes Combinations of nanotubes are formed, with a bimodal or trimodal distribution of oxidized discrete carbon nanotube diameters. Ideally, the dispersion of oxidized discrete carbon nanotubes includes a majority of oxidized discrete multi-walled carbon nanotubes, more desirably a majority of oxidized discrete double-walled carbon nanotubes, and even more desirably a majority of oxidized discrete single-walled carbon nanotubes carbon nanotubes. By majority is meant more than 50% by weight of all carbon nanotubes present in the dispersion.

In another embodiment of the present invention, the additively manufactured dispersion-bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is hydrogen bonded, ideally ionically bound, and more desirably covalently bound.

In another embodiment, the oxidized discrete carbon nanotubes further have a bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes, the bound dispersant ranging from about 50 to about 20,000 Daltons molecular weight composition. Desirably, the combined dispersant has a molecular weight ranging from about 60 to about 5000 Daltons, and more desirably from about 70 to about 1000 Daltons. The bound dispersants on the sidewalls of the oxidized discrete carbon nanotubes consist of chemical units selected from the group 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 incorporated dispersant desirably are capable of being crosslinked into the matrix.

The weight fraction of bound dispersant on the sidewalls of the discrete carbon nanotubes relative to oxidized discrete carbon nanotubes is greater than about 0.02 and less than about 0.8. The weight fraction of dispersant combined is desirably from about 0.03 to about 0.6, more desirably from about 0.05 to about 0.5, most desirably from about 0.06 to about 0.4.

The bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is selected such that it has good compatibility with the materials contacting the dispersant. Good compatibility in this specification refers to a sufficient amount of electrons, van der Waals force, ionic or dipole interactions, so that the oxidized carbon nanotubes can be dispersed into single or discrete carbon nanotubes rice tube. The bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is ideally selected such that it is thermodynamically miscible, ie, forms a homogeneous mixture with the material contacting the dispersant.

The bound dispersant on the sidewalls of the discrete carbon nanotubes may further include ethylene oxide molecular units. More desirably, the combined dispersant comprises a mixture of propylene oxide and ethylene oxide molecular units. There may be a mixture of dispersants bound to the sidewalls of the discrete carbon nanotubes or a mixture of oxidized discrete carbon nanotubes with different types bound to the dispersant.

In another embodiment of the invention, the bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes can be further selected to thermally decompose such that the ash content of the dispersant is low in nitrogen at temperatures below 500°C At about 5% by weight. Desirably, the bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes thermally decomposes such that the ash content of the dispersant is less than about 1% by weight in nitrogen at less than about 500°C, and more desirably The bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes thermally decomposes such that the dispersant has an ash content of less than about 1% by weight in nitrogen at less than about 400°C.

The oxidized discrete carbon nanotubes having an incorporated dispersant on the sidewalls of the oxidized discrete carbon nanotubes have an aspect ratio of from about 10 to about 10,000 (referred to as the length-to-diameter ratio of the oxidized discrete carbon nanotubes) ratio) composition. The aspect ratio desirably ranges from about 300 to about 10,000 for oxidized discrete single-walled carbon nanotubes, from about 150 to about 5,000 for oxidized discrete double-walled carbon nanotubes, and for oxidized discrete multi-walled carbon nanotubes. For carbon nanotubes, the aspect ratio is desirably from about 40 to about 500.

The aspect ratio of the oxidized discrete carbon nanotubes may be unimodal, or multimodal (eg, bimodal or trimodal). A multimodal distribution may have a uniform distribution of aspect ratio ranges (eg, 50% of one L/D range and about 50% of another L/D range). The distribution can also be asymmetric—meaning that a relatively small percentage of discrete nanotubes can have one particular L/D, while a larger number of discrete nanotubes can include another distribution of aspect ratios.

It is an embodiment of the invention that the oxidized discrete carbon nanotubes having dispersants bound to their sidewalls are present in a weight range of greater than zero and up to about 30 weight percent, based on the total weight of the dispersion . Desirably, the weight of the oxidized discrete carbon nanotubes with the dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes present in the dispersion ranges from about 0.01 to about 10 weight percent, more preferably based on the total weight of the dispersion. Ideally from about 0.01 to about 5% by weight.

In another embodiment of the invention, the majority of carbon nanotubes present in the dispersion are discrete. At least about 51% by weight of the oxidized carbon nanotubes present on the sidewalls of the ideal dispersion are discrete, and at least about 65% by weight of the oxidized carbon nanotubes present in the ideal dispersion are discrete. The oxidized carbon nanotubes with bound dispersant on the sidewalls of the carbon nanotubes are discrete, and more desirably at least about 75% by weight of the oxidized carbon nanotubes with bound dispersant on the sidewalls of the dispersion are present in the dispersion. The carbon nanotubes are discrete, and most ideally at least about 85% by weight of the carbon nanotubes present in the dispersion are discrete.

In another embodiment of the present invention, the dispersion of oxidized discrete carbon nanotubes having a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes comprises (in % by weight) relative to the total weight of the dispersion ) from about 0.05% to about 80% filler. Desirably, the weight percent of filler is from about 0.05% to about 30%, most desirably from about 0.1% to about 10%, relative to the total weight of the dispersion.

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 roughly spherical particles, rods, fibers or plates. Desirably, the filler has at least one size range greater than about 1 nm and less than about 10 microns, more desirably has at least one size range greater than about 5 nm and less than about 2 microns, and most desirably has at least one size range greater than about 10 nm and less than about 1 micron Size range.

In some embodiments, the dispersion comprising oxidized discrete carbon nanotubes further comprises a mixture of at least two different fillers. In some embodiments, the dispersion comprising oxidized discrete carbon nanotubes further comprises a mixture of different kinds of single fillers which may vary in terms of particle size, thermal conductivity, packing or molecular weight.

In a further embodiment of the invention, the dispersion further comprises a photocrosslinkable monomer, oligomer or polymer. Crosslinkable monomers, oligomers or polymers containing carbon-carbon double bonds, carbon-carbon triple bonds, urethanes, acrylates, alkyl acrylates, cyanonitriles, cyanoacrylates, nitriles, Molecular unit of the group of epoxy resins, amides, amines, alcohols, ethers and esters.

In another embodiment, the dispersion of oxidized discrete carbon nanotubes with a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes further comprises a thermoplastic. Dispersions of oxidized discrete carbon nanotubes with bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes can be coated with thermoplastic or have bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes Oxidized discrete carbon nanotubes can be dispersed within thermoplastics. Desirable 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 Polyethylene styrene blend (PC-ABS), polyetherimide (PEI), polyphenylene styrene (PPSF), polyethylene terephthalate (PET), polyethylene terephthalate Glycols (PETG), polyetheretherketone (PEEK), polyamides (such as but not limited to nylon 12, nylon 11, nylon 6, and nylon 6,6), polyvinyl alcohol and its copolymers, polyvinyl butyrate Esters and their copolymers, polyvinylpyrrolidone and its copolymers, polyethers and their copolymers. Thermoplastics can be linear polymers, graft polymers, comb polymers or block polymers.

In yet another embodiment, the dispersion of oxidized discrete carbon nanotubes with a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes further comprises an elastomer. The elastomer may be selected from, but not limited to, the group consisting of: natural rubber, polyisobutylene, polybutadiene, styrene-butadiene, hydrogenated styrene-butadiene, butyl rubber, polyisoprene, Styrene-isoprene rubber, EPDM rubber, silicone resin, polyurethane, polyester, polyether, polyacrylate, hydrogenated and non-hydrogenated nitrile rubber, halogen modified elastomer, polyolefin elastomer, containing Fluoroelastomers and combinations thereof. Elastomers can be non-crosslinked or crosslinked, grafted or copolymers.

In another embodiment, the dispersion of oxidized discrete carbon nanotubes having a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes further comprises a polymer impact resistant polymer having a glass transition temperature of less than about 25°C. Modifiers (impact modifiers). Impact modifier selected from the group of polyethers, polyesters, vinyl polymers, polyethylene copolymers, polyolefin polyacrylates, polyurethanes, polyamides and polysiloxanes, blends thereof and copolymers thereof . They can be further functionalized with reactive groups such as, but not limited to, epoxy, hydroxyl, isocyanate, and carboxyl groups.

Impact modifiers are ideally separated from the main matrix material of the dispersion, but still have good cohesive or thermodynamic interactions. More desirably, the composition of the impact modifier is a block copolymer or a core-shell polymer. Examples of core shell polymers are acrylate or butadiene based PARALOID™ impact modifiers. More desirably, the impact modifier has a refractive index value that is at least within 0.03 units, more desirably within 0.02 units, of the matrix refractive index value in order to minimize radiation scatter in the UV-visible wavelength range.

Core-shell particles may comprise more than one core and/or more than one shell. Furthermore, mixtures 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 curable resin. In one embodiment, the composition of the impact modifier is about a 7 to 1 diameter ratio (eg, 140 nm particles to 20 nm particles) and a weight percent ratio of about 4 to 1. In another embodiment, the composition of the impact modifier is about a 5 to 1 diameter ratio and about a 4 to 1 weight percent ratio. In another embodiment, the composition of the impact modifier is about 5 to 1 diameter ratio and about 6 to 1 weight percent ratio.

In a dispersion of oxidized discrete carbon nanotubes with a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes, the phase-separated domain size of the impact modifier can have a diameter greater than about 0.005 microns and less than about 1 micron, ideally greater than about 0.01 micron and less than about 0.8 micron in diameter, most desirably greater than about 0.05 micron and less than about 0.6 micron in diameter.

The impact modifier may be present at least about 0.1% to less than about 30% by weight of the dispersion, desirably at least greater than about 0.5% to less than about 15%, and most desirably at least about 2% to less than about A dispersion of oxidized discrete carbon nanotubes with a dispersant bound on the sidewalls of the discrete carbon nanotubes.

In another embodiment, the dispersion of oxidized discrete carbon nanotubes with a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes further comprises a metal powder. The metal powder may contain any of the metal elements listed in the periodic table. Metals may also be in the form of metal oxides, metal carbides, metal silicides or metal nitrides, or alloys with other elements. Ideal metal powders can be selected from, but not limited to the categories of Stainless Steel, Inconel, Bronze, Copper, Silver, Platinum, Tungsten, Aluminum, Cobalt, Platinum and Tungsten Carbide. More desirably, the metal powder has a particle diameter greater than about 1 nm and less than about 20 microns. For more efficient sintering, it may further be desirable to have a bimodal metal powder particle diameter distribution. It is further desirable that in the particle distribution of the metal powder, the number of larger particle sizes predominates.

In another embodiment, the dispersion of oxidized discrete carbon nanotubes having a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes further comprises a ceramic powder. Ceramic powders may be selected from, but are not limited to, the classes of alumina, zirconia, silica, boron nitride, and silicon carbide, and mixtures thereof. Desirably, the particle diameter of the ceramic powder is greater than about 1 nm and less than about 20 microns. For more efficient sintering of ceramics, it may further be desirable to have a bimodal ceramic powder particle diameter distribution. It is further desirable that in the particle distribution of the ceramic powder, the number of larger particle sizes accounts for the majority.

In another embodiment, the dispersion of oxidized discrete carbon nanotubes having a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes further comprises a mixture of ceramic powder and metal powder which upon sintering forms Cermet. Ideal cermets are based on carbides, nitrides, borides and silicides of elements from groups 4 to 6 of the periodic table.

In another embodiment of the present invention, the dispersion of oxidized discrete carbon nanotubes having a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes further comprises At least one additional dispersant selected from the group consisting of anionic, cationic, nonionic and zwitterionic surfactants, polyvinyl alcohol, polyvinyl alcohol and polyvinyl alcohol Copolymers of vinyl acetate, polyvinylpyrrolidone and its copolymers, carboxymethylcellulose, carboxypropylcellulose, carboxymethylpropylcellulose, hydroxyethylcellulose, polyetherimide, polyether, starch and mixtures thereof. Desirable non-covalently linked polymeric dispersants are selected from the group of amphiphilic polymers.

The additional dispersant attached to the sidewalls of the oxidized discrete carbon nanotubes desirably has a molecular weight in the range of about 100 to about 400,000 Daltons, more desirably in the range of about 1000 to about 200,000 Daltons, most desirably in the range of about 10,000 to about 200,000 Daltons In the range of about 100,000 Daltons.

The additional dispersant attached to the sidewalls of the oxidized discrete carbon nanotubes and the combined dispersant on the sidewalls of the oxidized discrete carbon nanotubes can be attached to the additional dispersants of the oxidized discrete carbon nanotubes at about 0.01 to about 2 The weight ratio of dispersant to bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is present in the dispersion. Desirably, the weight ratio is from about 0.1 to about 1, and more desirably from about 0.2 to about 0.75.

Another embodiment of the present invention is the dispersion of oxidized discrete carbon nanotubes having a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes further comprising an organic solvent. Desirable organic solvents are selected from the group of alcohols, ethers, ketones, dioxolanes, acetates, diols and mixtures thereof.

Yet another embodiment of the present invention is the dispersion of oxidized discrete carbon nanotubes having a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes further comprising water.

In one embodiment of the invention, the dispersion of oxidized discrete carbon nanotubes with a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes is electrostatically dissipative. Ideally, the dispersion has a surface resistivity of less than 10 billion ohms per square, more desirably less than 10 million ohms per square.

In yet another embodiment of the present invention, the dispersion of oxidized discrete carbon nanotubes having a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes further comprises from about 0.1% to about 20% by weight nitrogen atom.

In one embodiment of the invention, for a concentration of 2.5 x 10 ^-5 g/ml of oxidized discrete carbon nanotubes with bound dispersant in the dispersion, there is The dispersion of oxidized discrete carbon nanotubes with the combined dispersant has a UV-visible absorption at 500 nm of greater than 0.5 absorbance units. Ideally, greater than 0.75 absorbance units at the same concentration of oxidized carbon nanotubes and measurement wavelength, and most ideally, greater than 1 absorbance unit at the same concentration of oxidized carbon nanotubes and measurement wavelength.

In yet another embodiment of the present invention, the filler may be selected from the group consisting of carbon formers, expansion agents, and flame retardants that react in the gas phase (such as but not limited to organic halides (halogenated alkanes)).

In one embodiment, the dispersion of oxidized discrete carbon nanotubes having a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes comprises a material selected from the group consisting of thermally conductive materials such as, but not limited to, metals and metal alloys, nitrided carbon nanotubes, Fillers of the group of boron, alumina, silicon nitride, aluminum nitride, diamond, graphite).

In another embodiment, the dispersion of oxidized discrete carbon nanotubes having a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes comprises a material selected from magnetic and ferromagnetic materials such as, but not limited to, containing nickel atoms. , iron atoms, cobalt atoms and those materials of their alloys and oxides).

One embodiment of the present invention is a dispersion of oxidized discrete carbon nanotubes having an incorporated dispersant, the dispersion further comprising providing electromagnetic absorption or Masked magnetic or ferromagnetic particles. Dispersions of oxidized discrete carbon nanotubes with incorporated dispersants further comprising electron conductive filler particles are also ideal for radio frequency masking.

In yet another embodiment, a dispersion of oxidized discrete carbon nanotubes comprising at least a portion of the crosslinkable moiety and having a dispersant bound on at least one sidewall of the oxidized discrete carbon nanotubes is at least partially crosslinked by radiation , followed by post-curing by thermal or irradiation methods the oxidized discrete carbon nanotubes comprising at least a portion of the crosslinkable moiety and having a dispersant bound on at least one sidewall of the oxidized discrete carbon nanotubes to obtain the final desired part properties, where the time to post cure to achieve the final desired part properties is 10% less, ideally 25% less time, and more desirably 50% less time than a dispersion of discrete carbon nanotubes without oxidation.

In another embodiment, the dispersion of oxidized discrete carbon nanotubes comprising at least a portion of the crosslinkable portion and having a dispersant bound to at least one sidewall of the oxidized discrete carbon nanotubes is sprayable.

In another embodiment, the dispersion of oxidized discrete carbon nanotubes comprising at least a portion of the crosslinkable moiety and having a dispersant bound on at least one sidewall of the oxidized discrete carbon nanotubes further comprises Similar dispersions containing oxidized discrete carbon nanotubes have about 10% lower radiant power, ideally use about 25% lower radiant power, and more ideally use about 50% lower radiant power than similar dispersions without oxidized discrete carbon nanotubes % of the radiant power to sinter the material.

In one embodiment, the dispersion of oxidized discrete carbon nanotubes with bound dispersant further comprises an elastomer, wherein the final part exhibits a better performance under cycle fatigue than oxidized discrete carbon nanotubes without bound dispersant Similar dispersions of rice tubes have at least about 20% higher fracture resistance, desirably at least about 50% higher fracture resistance, and most desirably at least about 100% higher fracture resistance.

Other implementations

Embodiment 1. An additively manufactured dispersion, wherein the dispersion comprises at least a portion of a crosslinkable portion and oxidized discrete carbon nanotubes within the oxidized discrete carbon nanotubes At least one sidewall of the tube has a bound dispersant, wherein the oxidized discrete carbon nanotubes are present in a range of greater than 0 up to about 30 wt. % based on the total weight of the dispersion, and the majority of carbon present in the dispersion Nanotubes are discrete.

Embodiment 2. The dispersion of embodiment 1, wherein the oxidized discrete carbon nanotubes comprise an inner surface and an outer surface, each surface comprising an inner surface oxidized species content and an outer surface oxidized species content, wherein The inner surface oxidized matter content differs from the outer surface oxidized matter content by at least about 20%, and up to 100%.

Embodiment 3. The dispersion according to embodiment 1, wherein the oxidized discrete carbon nanotubes comprise oxidized discrete single-walled carbon nanotubes, oxidized discrete double-walled carbon nanotubes, and oxidized discrete multi-walled carbon nanotubes. The combination of walled carbon nanotubes forms a mixture of oxidized discrete carbon nanotubes having a bimodal or trimodal distribution of oxidized discrete carbon nanotube diameters.

Embodiment 4. The dispersion of embodiment 1, wherein the bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is covalently bound.

Embodiment 5. The dispersion of embodiment 1, wherein the bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes comprises an average molecular weight in the range of about 50 to about 20,000 Daltons, and the discrete carbon nanotubes The weight fraction of bound dispersant on the nanotube sidewalls relative to oxidized discrete carbon nanotubes is greater than about 0.02 and less than about 0.8.

Embodiment 6. The dispersion of embodiment 1, wherein the bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is miscible with a material contacting the bound dispersant.

Embodiment 7. An additive manufacturing dispersion, wherein said dispersion comprises at least a portion of crosslinkable acrylate moieties and oxidized discrete carbon nanotubes, said oxidized discrete carbon nanotubes in said oxidized discrete At least one sidewall of the carbon nanotubes has a bound dispersant, wherein the bound dispersant on the sidewalls of the discrete carbon nanotubes comprises molecular units selected from the group of ethers.

Embodiment 8. The dispersion of embodiment 7, wherein the molecular units comprise ethylene oxide.

Embodiment 9. The dispersion of embodiment 1, further comprising from about 0.1% to about 30% by weight of the dispersion in % by weight of a filler 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.

Embodiment 10. The dispersion of embodiment 1, further comprising a member of the group consisting of thermoplastics, thermosets, and elastomers.

Embodiment 11. The dispersion of embodiment 1, further comprising a core-shell elastomer further comprising a particle diameter of about 0.01 to about 1 micron.

Embodiment 12. The dispersion of embodiment 1, further comprising semiconductor powder, metal powder, and or ceramic powder having a particle diameter of from about 1 nm to about 20 microns.

Embodiment 13. The dispersion according to embodiment 1, further comprising at least one additional dispersant attached to the sidewalls of the oxidized discrete carbon nanotubes, said additional dispersant selected from the group consisting of anionic surfactants, cationic surfactants Agents, nonionic surfactants and zwitterionic surfactants, polyvinyl alcohol, copolymers of polyvinyl alcohol and polyvinyl acetate, polyvinylpyrrolidone and its copolymers, carboxymethyl cellulose, carboxypropyl cellulose, carboxy Group consisting of methylpropylcellulose, hydroxyethylcellulose, polyetherimines, polyethers, starches and mixtures thereof.

Embodiment 14. The composition of Embodiment 1, wherein the oxidized discrete carbon nanotubes comprise from about 0.1% to about 20% by weight nitrogen atoms.

Embodiment 15. An additive manufacturing dispersion, wherein the dispersion comprises at least a portion of a thermoplastic portion and discrete carbon nanotubes having bonded on at least one sidewall of the discrete carbon nanotubes The dispersant of wherein the discrete carbon nanotubes are present in an amount greater than 0 up to about 30% by weight based on the total weight of the dispersion.

Embodiment 16. The dispersion of embodiment 15, wherein the bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is at an ash content of less than about 5% by weight in nitrogen at less than about 500°C Thermally decomposes at least partially.

Embodiment 17. The additively manufactured dispersion of embodiment 15, wherein the majority of the carbon nanotubes are discrete.

Embodiment 18. The dispersion according to embodiment 1, wherein the part produced by additive manufacturing has a resistance of less than about 10 billion ohms per square.

^Embodiment 19. The dispersion according to embodiment 1, wherein the dispersion has a UV-visible Absorption is greater than about 0.5 absorbance units.

Embodiment 20. The dispersion according to embodiment 1, further comprising a filler selected from the group of thermally conductive materials such as, but not limited to, metals and metal alloys, boron nitride, aluminum oxide, silicon nitride, nitrogen aluminum oxide, diamond, graphite and graphene.

Embodiment 21. An additively manufactured dispersion for at least partially encapsulating an electronic component, wherein the dispersion comprises: at least a portion of the crosslinkable moiety; and Oxidized discrete carbon nanotubes; wherein the oxidized discrete carbon nanotubes include a dispersant bound to the sidewalls of the oxidized discrete carbon nanotubes; and wherein 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 Most of the carbon nanotubes present in the dispersion are discrete.

In the following description, certain details are set forth (eg, specific quantities, dimensions, etc.) in order to provide a comprehensive understanding of the embodiments disclosed in this specification. It will be apparent, however, to one skilled in the art that the present invention may be practiced without such specific details. In many instances, pertinent details (such considerations, etc.) have been omitted since such details are not necessary to gain a complete understanding of the invention and are within the skill of one having ordinary knowledge in the relevant fields.

Although most of the terms used in this specification are recognizable to those of ordinary skill in the art, it should be understood that when not explicitly defined, the terms should be interpreted as currently accepted by those of ordinary skill in the art. meaning. Where the interpretation of a term would render it meaningless or essentially meaningless, then the definition should be taken from Webster's Dictionary, 3rd Edition, 2009. Definitions and/or interpretations should not be incorporated from other related or unrelated patent applications, patents or publications unless specifically stated in this specification, or where incorporation is necessary to maintain validity.

In various embodiments, a dispersion is disclosed comprising oxidized discrete carbon nanotubes having a dispersant bound on at least one sidewall of the oxidized discrete carbon nanotubes, wherein the oxidized discrete carbon nanotubes The carbon nanotubes are present in an amount greater than 0 up to about 30 weight percent based on the total weight of the dispersion, and the majority of the carbon nanotubes present in the dispersion are discrete.

Carbon nanotubes made using metal catalysts such as iron, aluminum, or cobalt can retain a significant amount of catalyst bound or trapped within the carbon nanotubes, as much as 5% by weight or more. These residual metals may be detrimental in such applications (eg electronics) due to enhanced corrosion, or may interfere with the vulcanization process in cured elastomeric composites. In addition, these divalent or polyvalent metal ions can combine with the carboxylic acid groups on the carbon nanotubes and interfere with the dispersion of the carbon nanotubes in the subsequent dispersion process. In one embodiment, a dispersion is disclosed comprising oxidized discrete carbon nanotubes having a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes, the dispersion comprising less than about a hundred A residual metal concentration of 50,000 parts per million (50,000 ppm), and ideally less than about 10,000 parts per million. Residual catalyst concentration can be conveniently determined by using thermogravimetric analysis by heating from 25°C to 800°C at 5°C/min in nitrogen, then switching the gas to air and holding at 800°C for 30 minutes . The residual ash % is determined by the weight of the remaining material compared to the weight of the starting material. The ash can then be analyzed for metal types using energy dispersive X-ray and scanning electron microscopy. Alternatively, oxidized discrete carbon nanotubes can be isolated from the dispersion medium and analyzed using atomic absorption techniques.

The oxidation level of oxidized discrete carbon nanotubes is defined as the amount (by weight) of oxidized species covalently bound to the carbon nanotubes. The thermogravimetric method used to determine the weight percent of oxidized species on CNTs involved taking approximately 5 mg of dry oxidized CNTs and heating them at 5 °C/min from room temperature to 800 °C in a dry nitrogen atmosphere. Celsius. The percent weight loss from 200 to 600 degrees Celsius was taken as the percent weight loss of the oxidized species. Oxidized species can also be quantified using Fourier Transform Infrared Spectroscopy (FTIR), particularly in the wavelength range from 1680 to 1730 cm ⁻¹ .

Oxidized carbon nanotubes may have oxidized species including carboxylic acids or carbonyl-containing derivatives. Carbonyl derivatives may include ketones, quaternary amines, amides, esters, acyl halides, monovalent metal salts, and the like. Alternatively, or in addition, the carbon nanotubes may comprise oxidized species selected from hydroxyl groups or derived from hydroxyl-containing species, ketones, and lactones.

The term "discrete", alternatively referred to as the term "exfoliated", refers in this specification to individual carbon nanotubes substantially separated along their length, ie not bundled. The aspect ratio is defined as the ratio of the length to the diameter of a carbon nanotube. If there is a bundle of carbon nanotubes, the aspect ratio is considered to be the ratio of the length to the diameter of the bundle. For spherical spheres with wound carbon nanotubes, the aspect ratio is considered to be 1.

Depending on the desired application, the aspect ratio of the oxidized discrete carbon nanotubes can be a unimodal distribution, or a multimodal distribution (eg, a bimodal or trimodal distribution). A multimodal distribution may have a uniform distribution of aspect ratio ranges (eg, 50% of one L/D range and about 50% of another L/D range). The distribution can also be asymmetric—meaning that a relatively small percentage of discrete nanotubes can have one particular L/D, while a larger number of discrete nanotubes can include another distribution of aspect ratios. The aspect ratio of oxidized discrete carbon nanotubes can be determined, for example, using a dilution of the dispersion in an organic solvent and scanning electron microscopy.

Manufacturers of carbon nanotubes that may be suitable for use in applications described herein 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.

One way to obtain discrete carbon nanotubes is to subject the carbon nanotubes to high mechanical forces. During shearing, samples may be subjected to strong destructive forces resulting from shearing (turbulence) and/or cavitation, where processing equipment can generate energy densities as high as 10 ⁶ to 10 ⁸ Joules/m ³ . Equipment meeting this specification includes, but is not limited to, sonicators, cavitators, mechanical homogenizers, pressure homogenizers, and microfluidizers. One such homogenizer is shown in US Patent 756,953, the disclosure of which is incorporated herein by reference. Additional shearing devices include, but are not limited to, HAAKE™ mixers, Brabender mixers, Omni mixers, Silverson mixers, colloid mills, Gaullin homogenizers, and/or twin-screw extruders. After the shearing process, the carbon nanotube bundles have loosened, exposing a greater number of nanotube surfaces and/or a greater portion of the nanotube surfaces to the surrounding environment. Typically, a majority, desirably at least about 60%, more desirably at least about 75%, most desirably at least about 95% and up to 100% based on a given starting amount of entangled as-made and fabricated carbon nanotubes High surface area oxidized carbon nanotubes are produced by this process, a small number of tubes, usually very few tubes, remain tightly packed, and the surfaces of such tightly packed nanotubes are substantially inaccessible.

In various patent applications (e.g., US2012-0183770A1 and US2011-0294013 A1), Bosnyak et al. prepared discrete carbon nanotubes by judiciously and substantially simultaneously using oxidation and shear forces to oxidize the interior of the nanotubes. The surface and outer surfaces, usually to approximately the same level of oxidation, produce individual or discrete tubes.

In many embodiments, the present invention differs from those earlier applications and publications of Bosnyak et al. During the process of oxidizing the carbon nanotubes and incorporating the dispersant on the sidewalls of the oxidized discrete carbon nanotubes, the degree of fibrillation of the carbon nanotubes (which varies with the content or type of oxygen-containing species) can be Affects the number of carbon nanotubes and also affects the bound dispersant on the oxidized carbon nanotube sidewalls. For example, if many tubes are arranged in a trunk, the tubes within the core of the trunk are less likely to contain oxidizing species that react with nitric acid than the tubes in the outermost portion of the trunk. For a more uniform population of modified carbon nanotubes, it is desirable to have discrete or open carbon nanotube structures during the reaction of the modified carbon nanotubes. For some applications, such as, but not limited to, electrical conductivity in dual-phase materials, it may be desirable to control the degree of fibrillation of the carbon nanotube bundles to obtain a distribution of the bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes.

A dispersion comprising oxidized discrete carbon nanotubes with a dispersant bound on the sidewalls of the oxidized discrete carbon nanotubes can be prepared by first preparing the oxidized discrete carbon nanotubes and then incorporating the dispersant in the oxidized carbon nanotubes. On the sidewalls or ends of the discrete carbon nanotubes, or alternatively prepare oxidized carbon nanotubes, then combine the dispersant on the sidewalls or ends of the oxidized carbon nanotubes, and then make the Discrete carbon nanotubes.

Although not limited by the chemistry of covalently bonding the dispersant to the carbon nanotubes, the carboxylic acid groups on the carbon nanotubes are typically used to react with the amine functional groups of the dispersant of choice. An example of, but not limited to, a suitable dispersant is a commercial product from Huntsman Corporation, which is 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 moieties for covalently bonding molecules to the sidewalls of carbon nanotubes include, but are not limited to, azide, acyl halide, and silane moieties.

Dispersions of oxidized discrete carbon nanotubes with incorporated dispersants can be advantageously used in additive manufacturing to generate heat by employing near-infrared to up to 1 terahertz radio frequency radiation that is rapidly absorbed by the carbon nanotubes to generate heat To improve processability and component performance. This effect can be used to improve the time required to fully cure the crosslinkable molecule, improve sintering of the material and reduce part warpage.

An example of a suitable impact modifier is an elastomer, more desirably preformed elastomer particles. These elastomers have a glass transition temperature (Tg) below 0°C, ideally below -20°C.

The particle size of the impact modifying component can be obtained by 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 Corporation. The ideal method for measuring particle size is laser diffraction particle size analysis according to ISO13320:2009. Information on such an analysis can be found in Setting New Standards for Laser Diffraction Particle Size Analysis. Alan Rawle and Paul Kippax, Laboratory Instrumentation News, 21 January 2010.

The monomer or solvent of the liquid radiation-curable resin used for analysis can affect the measured average particle size. In addition, laser diffraction analysis may require the use of solvents or other low-viscosity dispersants. These solvents can affect the measured average particle size. For the purposes of this study, dispersed average particle sizes refer to those particles that have been exposed to the listed monomers for a given formulation, dispersed, and then analyzed using propylene carbonate as the solvent for laser diffraction particle size analysis. Particle size analysis is performed on dispersions of impact modifier particles, and in dilute propylene carbonate solutions, concentrations of 0.1-0.4 g dispersion in 10 g propylene carbonate are typically used.

Suitable impact-modifying components are elastomers based _on copolymers of ethylene or propylene with one or more _C2 to C12 olefinic monomers, which can be blended into an oxidized Dispersions of Discrete Carbon Nanotubes.

Examples of this are ethylene/propylene copolymers or optionally containing a third copolymerizable diene monomer (EPDM) (e.g. 1,4-hexadiene, dicyclopentadiene, bicyclooctadiene, Ethylene/propylene copolymers of methylnorbornene, ethylidene norbornene and tetrahydroindene); ethylene/α-olefin copolymers such as ethylene-octene copolymers and ethylene/α-olefin/polyene copolymers .

Other suitable elastomers are polybutadiene, polyisoprene, styrene/butadiene random copolymers, styrene/isoprene random copolymers, acrylate rubbers (e.g., polybutylacrylate ), poly(hexamethylene carbonate), ethylene/acrylate random and acrylic block copolymers, styrene/butadiene/(meth)acrylate (SBM) block copolymers, styrene / Butadiene block copolymers (styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS) and its hydrogenated forms, SEBS, SEPS) and (SIS) and ionomers.

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 copolymer (Arkema) and Surlyn ionomer (Dupont).

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

Optionally, the elastomer can be cross-linked after mixing into the dispersion of oxidized discrete carbon nanotubes with incorporated dispersant. A crosslinked structure can be introduced by a conventional method. As examples of crosslinking agents for such materials, peroxides, sulfur, cresol, etc., optionally with polyfunctional monomers such as divinylbenzene, ethylene glycol di(meth)acrylic acid ester, diallyl maleate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, trimethylolpropane triacrylate, methacrylic acid allyl ester, etc.) combination.

In one embodiment, the impact modifier that can be mixed into the dispersion of oxidized discrete carbon nanotubes with incorporated dispersant is preformed elastomeric particles. Elastomeric particles can be prepared by various methods, including those obtained by isolation from a latex prepared by emulsion polymerization, or prepared in situ in another component of the composition.

Suitable commercial sources of such prefabricated elastomeric particles are PB (polybutadiene) latex or PBA (polybutyl acrylate) latex with different average particle sizes available from various manufacturers, or by emulsifying EPDM, Latex obtained from SBS, SIS or any other rubber.

Optionally, the elastomer may contain a cross-linked structure. A crosslinked structure can be introduced by a conventional method. As examples of crosslinking agents for such materials, peroxides, sulfur, cresol, etc., optionally with polyfunctional monomers such as divinylbenzene, ethylene glycol di(meth)acrylic acid ester, diallyl maleate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, trimethylolpropane triacrylate, methacrylic acid allyl ester, etc.) combination.

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

Optionally, reactive groups can be introduced into the shell by copolymerization, eg with glycidyl methacrylate, or by treating the shell to form reactive functional groups. Suitable reactive functional groups include, but are not limited to, epoxy groups, trimethoxylate groups, hydroxyl groups, carboxyl groups, vinyl ether groups, and/or acrylate groups.

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 Ltd.), Durarstrength D400, Durarstrength 400R (manufactured by Arkema Group), Paraloid EXL-2300 (non-functional shell), Paraloid EXL-2314 (epoxy functional shell), Paraloid EXL-2600, Paraloid KM 334 and Paraloid EXL 2300G. Paraloid core-shell elastomers are manufactured by Dow Chemical Company, Genioperl P53, Genioperl P23, Genioperl P22 are manufactured by Wacker Chemie, Kane Ace MX products (manufactured by Kaneka).

Other examples _of such elastomeric particles are crosslinked polyorganosiloxane rubbers, which may include dialkylsiloxane repeating units, where "alkyl" is C to C ₆ alkyl. Such particles can be prepared by the methods disclosed in US Patent No. 4,853,434 to Block, which is hereby incorporated by reference in its entirety. The particles can be modified to include reactive groups such as oxirane, glycidyl, trimethoxyester, hydroxyl, vinylester, vinylether or (meth)acrylate groups or combination, ideally on the surface of the granules. An example of a commercially available polyorganosiloxane elastomer particle is Albidur.

EP 2240 (A), Albidur EP 2640, Albidur VE 3320, Albidur EP 5340, Albidur EP 5640 and Albiflex 296 (dispersion of particles in epoxy resin or vinyl ether resin, Hanse Chemie, Germany), Genioperl M41C (cyclo Dispersions in epoxy resins, Wacker Chemicals), Chemisnow MX series and MP series (Soken Chemical and Engineering Company). Other materials that can be used to make core-shell particles for use in the present invention can be found, for example: Nakamura et al., J Appl. Polym. Sci. v 33 n 3 Feb. 20, 1987 pp. 885-897, 1987, which disclose Core-shell material with poly(butyl acrylate) core and poly(methyl methacrylate) shell. The shell is treated to contain epoxy groups; Saija, L.M. and Uminski, M., Surface Coatings International Part B 2002 85, No. B2, June 2002, pp. 149-53, which describe (Methyl methacrylate-butyl acrylate copolymer) prepared core and shell core-shell materials and treated with MMA or AMPS to produce materials 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) was used for the shell. The epoxide sites are the reactive sites on the shell of this material. In another embodiment, glycidyl methacrylate and methyl methacrylate are used as comonomers in the shell.

Core-shell particles may comprise more than one core and/or more than one shell. Furthermore, mixtures of core-shell particles and elastomer particles may be used. Two impact modifiers of different diameters may be used in a ratio to reduce the viscosity of dispersions comprising crosslinkable monomers or oligomers. For example, the composition of the impact modifier is about a 7 to 1 diameter ratio (ie, 140 nm diameter particles to 20 nm diameter particles) and about a 4 to 1 wt% ratio.

Another desirable feature of selecting an elastomer or impact modifier is selecting an elastomer or impact modifier composition having a refractive index value that is at least within 0.03 units of the refractive index value of the material in which it is dispersed , more ideally within 0.02 units, in order to minimize radiation scattering in the UV-visible wavelength range. An example of such a mixture is Paraloid KM 334, with a refractive index of 1.47, and Dymax BR-952-a urethane dimethacrylate, with a refractive index of 1.48.

The dispersion of oxidized discrete carbon nanotubes with bound dispersant further comprises (in weight %) of the dispersion from about 0.1% to about 30% by weight of a filler selected from the group consisting of carbon black, graphene, Group consisting of graphene oxide, reduced graphene, carbon fibers, silica, silicates, halloysite, clay, calcium carbonate, wollastonite, glass, flame retardants, and talc. Fillers can also be surface modified to improve their incorporation and distribution in the dispersion. An example of surface treatment is the use of silane coupling agents on silica particles.

A general method of determining the thermal conductivity of a dispersion is to apply a known heat flux to the sample and measure the temperature difference across the thickness of the sample once the steady state temperature of the sample has been reached. After assuming one-dimensional heat flow and an isotropic medium, the measured thermal conductivity is then calculated using Fourier's law,

Example 1 - Oxidation of Tuball ^™ (OCSiAl) In a 1 liter glass reactor equipped with a stirrer and condenser, 500 grams of 67% by weight nitric acid were heated to 95°C. To the acid was added 5 grams of single-walled carbon nanotubes (Tuball™) as received. As-is, fluffy carbon nanotubes have the form of tightly packed tree trunks that can be several millimeters in length and one millimeter in diameter. The mixture of acid and carbon nanotubes was mixed while maintaining the solution at about 95 degrees Celsius for 5 hours. At the end of the reaction period, the oxidized SWNTs were filtered to remove acid and washed with reverse osmosis (RO) water to pH 3-4. The resulting CNTs were oxidized to about 3.6% and contained 4.4% metal residues.

Example 2 - Oxidation of multi-walled carbon nanotubes, CNano Flotube 9000 4 liters of concentrated nitric acid containing 65% nitric acid were added to a 10 liter temperature-controlled reaction vessel equipped with a sonicator and stirrer. 40 grams of non-discrete multi-walled carbon nanotubes (Flowtube 9000 grade from CNano company) were charged into the reaction vessel while stirring the acidic mixture and maintaining the temperature at 85°C. The power of the sonicator was set at 130-150 watts, and the reaction was continued for 3 hours. After 3 hours, the viscous solution was transferred to a screening program with a 5 micron filter, and most of the acidic mixture was removed by filtration using 100 psi pressure. The filter cake was washed once with 4 liters of deionized water, then once with 4 liters of ammonium hydroxide solution having a pH greater than 9, and then twice more with 4 liters of deionized water. The resulting pH of the final wash was 4.5. A small sample of the filter cake was dried under vacuum at 100 °C for 4 h and subjected to thermogravimetric analysis as previously described. The amount of oxidized species on the fibers was 2.4% by weight, and the average aspect ratio as determined by scanning electron microscopy was 60. The residual catalyst content was determined to be 2,500 ppm.

Example 3 - Covalent attachment of dispersants to oxidized single-walled carbon nanotubes . The oxidized single-walled carbon nanotubes from Example 1 were used in the form of a wet cake with a water solids content of 6.6% by weight. 30.3 grams of the wet cake was mixed with 30 grams of isopropanol, then 3 grams of Jeffamine M2005 monoamine terminated polyether dissolved in 350 grams of isopropanol and 622 grams of water were added with stirring. Stirring was continued for 10 minutes. Transfer the slurry to a Waring mixer and mix on high speed for 10 minutes. The slurry was then passed through a laboratory scale homogenizer, maintaining the temperature below 45°C, until no large structures >20 microns in size were observed by optical microscopy. The resulting mixture was then filtered at 13 using a Buchner screening program and No. 2 Whatman filter paper, and washed 4 times with 100 ^cm3 of 35 wt% aqueous isopropanol. The washed wet cake was then dried first in a convection oven at 120°C to 95% solids and then in a vacuum oven at 150°C for 1 hour. This is referred to as SWNT MB in Table 3. TGA analysis in nitrogen at 5°C/min in the range 200-600°C yielded 47% covalently bound polyether.

Example 4 - Covalent attachment of dispersants to oxidized multi-walled carbon nanotubes . The oxidized multi-walled carbon nanotubes from Example 2 in the form of a wet cake with a water solids content of 5% by weight were used. 40 grams of the wet cake was mixed with 30 grams of isopropanol, then 2 grams of Jeffamine M2005 monoamine terminated polyether dissolved in 350 grams of isopropanol and 622 grams of water was added with stirring. Stirring was continued for 10 minutes. Transfer the slurry to a Waring mixer and mix on high speed for 10 minutes. The slurry was then passed through a laboratory scale homogenizer, maintaining the temperature below 45°C, until no large structures >20 microns in size were observed by optical microscopy. The resulting mixture was then filtered at 13 using a Buchner screening program and No. 2 Whatman filter paper, and washed 4 times with 100 ^cm3 of 35 wt% aqueous isopropanol. The washed wet cake was then dried first in a convection oven at 120°C to 95% solids and then in a vacuum oven at 150°C for 1 hour. TGA analysis in nitrogen at 5°C/min in the range 200-600°C yielded 18% covalently bound polyether.

Example 5 - Coating Nylon Powder Nylon 11 was ground into small powder particles less than 10 microns in diameter. The dispersion was prepared by adding 1 g of the carbon nanotubes of Example 4 and 1 g of polyvinylpyrrolidone (Sigma Aldrich) with a molecular weight of about 24,000 Daltons to 200 g of aqueous isopropanol (50/50). Stir 100 g of nylon 11 powder into the modified carbon nanotube dispersion and stir 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 dry dispersion coating. This powder can then be used in the SLS additive manufacturing method to create robust parts with enhanced electrical conductivity and resistance of less than 10 billion ohms per square. Coating of oxidized discrete carbon nanotubes with covalently attached dispersants allows for improved post-sintering annealing of components by infrared or radio frequency radiation.

Example 6 - Coating Ceramic Powders Alumina powder particles with a diameter of less than 10 microns were used. A dispersion was prepared by adding 1 g of the carbon nanotubes of Example 4 to 200 g of isopropanol along with 1 g of CNTs with a molecular weight of approximately 24,000 Daltons (Sigma Aldrich) and mixing in a Thinky mixer at 2000 rpm for 5 minutes. The dispersion is selectively sprayed onto a bed of alumina powder and the alcohol is removed by drying. The powder is combined with a dry dispersion of oxidized discrete carbon nanotubes, which can then be sintered to produce strong parts. Dispersions of oxidized discrete carbon nanotubes with covalently attached dispersant significantly improved the green strength of ceramic parts, and the covalently attached dispersant was removed during sintering. Oxidized discrete carbon nanotubes can be used to induce heating by electric/magnetic fields, or infrared or radio frequency radiation.

Example 7 - Mixing Radiation Curable Resin A radiation curable composition for tank photopolymerization was prepared by weighing the ingredients and filling into containers. The mixture is stirred mechanically at room temperature or elevated temperature (up to 80°C) until a homogeneous resin mixture is obtained. The prepared compositions were processed in a tank photopolymerization apparatus, and the manufactured samples were analyzed according to the test methods described below.

Make 3D samples The general procedure for preparing three-dimensional samples with a trough photopolymerization device is as follows. The radiation curable resin is poured into the tank. Fabrication parameters were set to standard black resin and 25 μm layer thickness. In this way, the resin is heated to 31°C before the part is fabricated. Depending on the composition of the resin, sufficient laser passes are used to provide the required polymerization energy. The material is exposed to laser light emitting in the 405 nm range. Initially a "green part" is formed in which the layers are not fully cured. Undercuring allows subsequent successive layers to adhere better by bonding when cured further. The fabricated "green parts" were removed from the machine, washed with isopropanol, dried in air, and post-cured in a curing chamber equipped with 405 nm multidirectional LED lamps. All samples were post-cured in a curing chamber for 30 minutes at room temperature unless otherwise specified.

Test Methods Resins are prepared to meet the desired viscosity and wetting behavior requirements. Viscosity and wetting behavior directly affect recoat depth (layer thickness before radiation exposure), which in turn affects build resolution in the z direction. Viscosity data for freshly prepared resins were collected using an HR20 Discovery Hybrid Rheometer (TA Instruments). A 40mm 2.002° stainless steel Peltier plate was used for flow scanning experiments. Logarithmic sweeps were performed by sweeping shear rates from 1.0e ⁻³ to 8000 l/s at room temperature. Additional flow temperature ramp tests were performed at a shear rate of 6 1/s and the temperature was ramped from 25°C to 80°C at a ramp rate of 2°C/min. Table 1 shows the viscosity of the compositions of the three examples at zero shear rate. The data show that viscosity increases exponentially with increasing content of oxidized discrete carbon nanotubes with bound dispersant 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 the viscosity decreases exponentially at a constant shear rate with increasing temperature.

Table 1 Example Viscosity at 25°C , [cP] 7.1 2,093 7.2 14,084 Control 1 2,284 Table 2 Example Viscosity at 25°C , [cP] Viscosity at 50℃ ,[cP] Viscosity at 80℃ ,[cP] 7.1 770 161 63 7.2 778 219 105 Control 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 amount of TPO and OB is not included in the total composition percentage. table 3 components Example 7.1 : [ % by weight ] Example 7.2 : [ % by weight ] Control 1 [ wt %] 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 was collected by testing Tensile Type IV samples (ASTM D638) fabricated using a trough photopolymerization apparatus. All samples were fabricated vertically. Tensile strength, Young's modulus, and elongation at break tests were performed after post-curing for 24 hours or more. Tensile testing was performed in accordance with ASTM D638, which is incorporated by reference in its entirety except that: no measures were taken to control room temperature and humidity, and the rod was not equilibrated within 2 days. Testing was performed on an Instron testing machine (Model 5985). Data reported are the average of three measurements. Table 3 shows the ultimate tensile strength, yield strength, and Young's modulus for Examples 7.1 and 7.2 compared to a control that did not incorporate oxidized discrete carbon nanotubes with incorporated dispersant into the composition. These examples show that the addition of oxidized discrete carbon nanotubes with incorporated dispersant increases tensile and yield strength as well as 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 Control 1 63.7±1 34.7±0.8 2.1±0.03 Cured samples for determination of Izod impact strength were prepared in the same manner as tensile bars except that the samples were designed according to the ASTM D-256A standard and had dimensions of 3.2 mm x 12.7 mm x 63.5 mm (thickness x width x length ). Samples were notched using a motorized notch cutter from Ray-Ran. Izod impacts were measured using a Ray-Ran Universal Pendulum Impact System equipped with a 2.75 J pendulum. Data reported are 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 incorporated dispersant significantly increases the impact strength of fabricated samples compared to resins without oxidized 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 Control 1 15.0 ** Control 2 11.3 ** Table 6 lists the components of each photocurable composition labeled as Examples 7.3, 7.4 and Control 2. Table 6 components Example 7.3 , [ % by weight ] Example 7.4 , [ % by weight ] Control 2 , [ wt %] Formlabs Clear 99.95 99.80 100.00 MWCNT 0.05 0.20 0.00

Cross References to Related Applications This application is a continuation-in-part of U.S. Serial No. 17/187,658, filed February 26, 2021, which itself is a continuation of U.S. Serial No. 16/012,265 (now U.S. Patent 10,934,447), filed June 19, 2018. Continuation-in-Part, Serial No. 16/012,265 is a continuation-in-part of U.S. Serial No. 15/288,553 filed October 7, 2016 (now U.S. Patent No. 9,636,649) filed August 1, 2016, 2016 Approved September 12, 2016 and issued as a Continuation-in-Part of U.S. Serial No. 15/225,215, filed May 27, 2016, and issued as U.S. Patent No. 9,422,413 166,931, which is a continuation-in-part of U.S. Serial No. 15/166,931, which is a continuation of U.S. Serial No. 14/924,246, which was filed on October 27, 2015 and issued as U.S. Patent No. 9,353,240, which was filed on June 11, 2013 And as a continuation of U.S. Serial No. 13/993,206 issued as U.S. Patent No. 9,212,273, which claims priority to PCT/EP2011/072427 filed December 12, 2011, which asserts Benefit to U.S. Provisional Application 61/423,033, filed December 14, 2010. All of the aforementioned US applications and/or issued patents are expressly incorporated herein by reference. This invention is also related to US Ser. Nos. 62/319,599; 14/585,730; 14/628,248; and 14/963,845.

Claims (22)

An additively manufactured dispersion characterized in that the dispersion includes at least a portion of a crosslinkable portion and oxidized discrete carbon nanotubes in at least one of the oxidized discrete carbon nanotubes having a bound dispersant on the sidewall, wherein the oxidized discrete carbon nanotubes are present in a range of greater than 0 up to about 30 wt. % based on the total weight of the dispersion, and the majority of the carbon nanotubes present in the dispersion are discrete of. The dispersion of claim 1, wherein the oxidized discrete carbon nanotubes comprise an inner surface and an outer surface, each surface comprising an inner surface oxidized species content and an outer surface oxidized species content, wherein the inner surface is oxidized The content of matter differs by at least about 20%, and up to 100%, from that of the outer surface oxidation. The dispersion according to claim 1, wherein the oxidized discrete carbon nanotubes comprise oxidized discrete single-walled carbon nanotubes, oxidized discrete double-walled carbon nanotubes and oxidized discrete multi-walled carbon nanotubes The combination of tubes forms a mixture of oxidized discrete carbon nanotubes having a bimodal or trimodal distribution of oxidized discrete carbon nanotube diameters. The dispersion of claim 1, wherein the bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is covalently bound. The dispersion of claim 1, wherein the bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes comprises an average molecular weight in the range of about 50 to about 20,000 Daltons, and the sidewalls of the discrete carbon nanotubes The weight fraction of bound dispersant on the oxidized discrete carbon nanotubes is greater than about 0.02 and less than about 0.8. The dispersion of claim 1, wherein the bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is miscible with a material contacting the bound dispersant. An additive manufacturing dispersion characterized in that the dispersion comprises at least a portion of a crosslinkable acrylate moiety and oxidized discrete carbon nanotubes within the oxidized discrete carbon nanotubes At least one sidewall has a bound dispersant, wherein the bound dispersant on the sidewall of the discrete carbon nanotubes comprises molecular units selected from the group of ethers. The dispersion according to claim 7, wherein the molecular unit comprises ethylene oxide. The dispersion as claimed in claim 1, wherein, further comprising fillers of about 0.1% by weight to about 30% by weight of the dispersion in % by weight, the fillers are selected from carbon black, graphene, graphene oxide, reduced graphite group consisting of alkenes, carbon fibers, silica, silicates, halloysite, clay, calcium carbonate, wollastonite, glass, flame retardants, and talc. The dispersion according to claim 1, further comprising members of the group consisting of thermoplastics, thermosetting plastics and elastomers. The dispersion of claim 1, further comprising a core-shell elastomer, the core-shell elastomer further comprising a particle diameter of about 0.01 to about 1 micron. The dispersion according to claim 1, further comprising semiconductor powder, metal powder and or ceramic powder having a particle diameter of about 1 nm to about 20 microns. The dispersion of claim 1, further comprising at least one additional dispersant attached to the sidewalls of the oxidized discrete carbon nanotubes, the additional dispersant being selected from anionic surfactants, cationic surfactants, Nonionic and zwitterionic surfactants, polyvinyl alcohol, copolymers of polyvinyl alcohol and polyvinyl acetate, polyvinylpyrrolidone and its copolymers, carboxymethyl cellulose, carboxypropyl cellulose, carboxymethyl Group consisting of propylcellulose, hydroxyethylcellulose, polyetherimides, polyethers, starches and mixtures thereof. The dispersion of claim 1, wherein the oxidized discrete carbon nanotubes comprise about 0.1% to about 20% by weight nitrogen atoms. An additively manufactured dispersion characterized in that the dispersion includes at least a portion of a thermoplastic portion and discrete carbon nanotubes having a dispersant bound to at least one sidewall of the discrete carbon nanotubes, wherein The discrete carbon nanotubes are present in an amount greater than 0 up to about 30 weight percent based on the total weight of the dispersion. The dispersion of claim 15, wherein the bound dispersant on the sidewalls of the oxidized discrete carbon nanotubes is at least partially thermally decomposed at less than about 500° C. in nitrogen with an ash content of less than about 5% by weight quantity. The dispersion according to claim 15, wherein most of the carbon nanotubes are discrete. The dispersion of claim 1, wherein the additively manufactured part has a resistance of less than 10 billion ohms per square. The dispersion of claim 1, wherein the dispersion has a UV-visible absorbance at 500 nm of greater than about 0.5 absorbance for a concentration of oxidized discrete carbon nanotubes in the dispersion of 2.5 x 10-5 g/ml unit. The dispersion as claimed in claim 1, further comprising a filler selected from the group 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. The dispersion according to claim 1, further comprising a biologically active substance selected from the group consisting of substances capable of interacting with bacteria, viruses, fungi and biological agents. An additive manufacturing dispersion for at least partially encapsulating electronic components, characterized in that the dispersion comprises: at least a portion of the crosslinkable moiety; and Oxidized discrete carbon nanotubes; wherein the oxidized discrete carbon nanotubes include a dispersant bound to the sidewalls of the oxidized discrete carbon nanotubes; and wherein 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 Wherein the majority of carbon nanotubes present in the dispersion are discrete.