Light-colored conductive coating

Abstract

The CNS millbase dispersion comprises a solvent and 0.5 wt. % or less of at least one CNS-derived material dispersed in the millbase dispersion, the at least one CNS-derived material being selected from the group consisting of carbon nanostructures, carbon nanostructure fragments, broken carbon nanotubes, and any combination thereof. The carbon nanostructures or carbon nanostructure fragments comprise a plurality of multi-walled carbon nanotubes that are branched, interdigitated, entangled, and / or cross-linked in a polymeric structure by sharing a common layer, and the broken carbon nanotubes are derived from carbon nanostructures and are branched and share a common layer with each other. The Brookfield viscosity of the dispersion measured at room temperature and 10 rpm is less than 3000 cP.

Description

Technical Field

[0001] Field of the Invention The present invention relates to the use of carbon nanostructures in conductive coatings, such as primers and transparent coatings for decorative and protective coatings.

Background Art

[0002] Automobile and other vehicle bodies have traditionally been made of sheet metal. Metal parts can be manufactured to have a smooth, glossy surface that provides the desirable shiny, sleek appearance for automobiles and other vehicles. Typically, metal body parts are attached to the vehicle chassis and then several layers of primer and coating are applied to achieve the final color and gloss. The electrical conductivity of the metal enables the application of these primers and coatings by electrostatic spraying.

[0003] It is desirable to make the external parts of vehicles from polymeric materials, because of their lighter weight compared to metals and the ease with which parts having incorporated and complex shapes can be molded. However, many polymeric materials are electrical insulators. Therefore, it is desirable to have a surface treatment for polymeric materials that enables the application of coatings using electrostatic methods.

[0004] Polymeric materials are also used to manufacture protective films for electronic displays and other packaging components for packaging trays, carrier tapes, and electronic parts and components. Often, such polymers cannot dissipate static electricity, which can damage electronic equipment.

[0005] Conductive fillers can be used to impart electrical conductivity to polymer materials, but the required loading amounts of materials such as carbon black or metallic powders can impart color and / or block light transmission. For example, for automobiles, it may be difficult to coat a dark color with a light color, and opacity can obscure the view of an electronic display or make it difficult to see packaged electronic components for both people and automated equipment.

[0006] Therefore, it is desirable to have surface treatments for polymers and other materials that can impart electrical conductivity while providing other aesthetic advantages such as transparency or ease of coating with other colored coatings. SUMMARY OF THE INVENTION

[0007] In one aspect, a curable coating composition contains a resin and a CNS-derived material at 10 wt% or less on a dry basis. In some embodiments, the curable coating composition and the coating contain carbon nanostructures, fragments of carbon nanostructures, and / or broken carbon nanotubes at 7 wt% or less on a dry basis, such as 1 wt% - 7 wt%, 2 wt% - 6 wt%, or 3 wt% - 5 wt%.

[0008] The composition is prepared using carbon nanostructures (CNSs, or CNS in the singular), which, as described herein, are a plurality of carbon nanotubes (CNTs) polymerically cross-linked by being branched, e.g., dendritically, meshing with each other, intertwining, and / or sharing a common layer with each other. The operations performed to prepare the compositions described herein can generate CNS fragments and / or broken CNTs. Fragments of CNSs are derived from CNSs and contain a plurality of CNTs that are polymerically cross-linked by being branched, meshing with each other, intertwining, and / or sharing a common layer, like larger CNSs. Broken CNTs are derived from CNSs, are branched, and share a common layer with each other. Although not bound to any specific interpretation, CNS fragments and / or broken CNTs are considered to be derived from or generated from CNSs during one or more processing steps (e.g., operations received to disperse or mix the initial CNSs in a carrier) involved in preparing the systems described herein.

[0009] Highly intertwined CNSs are macroscopic in size and can be regarded as having carbon nanotubes (CNTs) as the basic monomeric units of their polymeric structure. For many of the CNTs in the CNS structure, at least some of the lateral layers of the CNTs are shared with another CNT. In general, each carbon nanotube in a CNS does not necessarily have to be branched, cross-linked, or share a common layer with other CNTs, but at least some of the CNTs in the carbon nanostructure can be engaged with each other and / or with carbon nanotubes in the remainder of the carbon nanostructure that are branched, cross-linked, or share a common layer.

[0010] In certain examples, the CNS is provided at a loading of 0.01 - 1 wt% of the formulation. In many cases, a loading of 0.5 wt% or less is 10 7A surface resistivity of the coating of less than Ω / square and an L of, for example, at least 55, at least 60, at least 70, or at least 80 * can result in low coloration. For example, an L of at least 30, at least 40, or at least 50 * of a darker coating may also be acceptable in some cases.

[0011] CNS can provide various advantages over normal CNTs, perhaps due to its unique structure. Further, in contrast to CNTs, CNS can be provided in a form (e.g., powder) that is easy and safe to handle on an industrial scale. In some cases, CNS forms a stable dispersion in a desired solvent.

[0012] The present invention provides many other advantages. As already described, for example, the CNS used can generate fragments of CNS (including partially fragmented CNS) and / or broken CNTs. These structures can result in improved connectivity between each other, thereby improving electrical conductivity. The use of CNS can result in the formation of a flexible conductive network structure with good coverage in a coating at a low loading amount, while a low coloring power means that a light-colored coating can exhibit a desired color tone when deposited on a primer coating containing CNS. Similarly, a transparent coating containing CNS can provide a desired visibility for the underlying surface while also showing electrical conductivity.

[0013] In one embodiment, the coating composition comprises a resin and at least one CNS-derived material dispersed in the coating composition at 10 wt% or less on a dry basis, the at least one CNS-derived material being selected from the group consisting of carbon nanostructures, fragments of carbon nanostructures, broken carbon nanotubes, and combinations thereof. The carbon nanostructure or fragment of a carbon nanostructure comprises a plurality of multi-layer carbon nanotubes cross-linked in a polymeric structure by being branched, intermeshing, intertwining, and / or sharing a common layer, and the broken carbon nanotubes are derived from a carbon nanostructure, are branched, and share a common layer with each other, and when tested according to Evaluation Method A, the resulting cured coating has a surface resistivity of at most 10 7 Ω / square, an L value of at least 30, * or both. For example, the cured coating may have an L value of at least 30, at least 40, at least 50, at least 55, at least 60, at least 70, at least 80, at least 90, 30 - 80, or 40 - 70. *

[0014] When tested according to Evaluation Method B, the resulting cured coating has a transparency of greater than 55% and log 10 (surface resistivity) ≤ 0.005 (transparency) 2 ​It may have a resistivity (Ω / sq) that satisfies -0.52 (transparency) + 19 (where the transparency is given as a percentage). The CNS-derived material may be coated with a binder or be a mixture with a binder. This resin can be selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, vinyl-chloride copolymer, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyvinyl butyral, polyolefin, and cellulose resin. For example, the resin can be selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyolefin, and cellulose resin. The coating composition may further include at least one additive selected from titania, hydrophilic fumed silica, hydrophobic fumed silica, hydrophilic precipitated silica, hydrophobic precipitated silica, clay, bentonite, talc, metal carbonate, calcium carbonate, for example, titania. The cured coating produced by curing the coating composition of any of these embodiments may contain 0.01 to 10 wt% of the CNS-derived material, for example, 0.05 to 7 wt% of the CNS-derived material. The cured coating may further contain 20 to 30 wt% of titania and may have a value of at least 55 L * It may have a value of

[0015] In another embodiment, the CNS mill base dispersion comprises a solvent and at least one CNS-derived material dispersed in the coating composition at 0.5 wt% or less, the at least one CNS-derived material being selected from the group consisting of carbon nanostructures, fragments of carbon nanostructures, broken carbon nanotubes, and any combination thereof. The carbon nanostructure or fragment of a carbon nanostructure comprises a plurality of multi-walled carbon nanotubes cross-linked in a polymeric structure by branching, intermeshing, entangling, and / or sharing a common layer, and the broken carbon nanotubes are derived from a carbon nanostructure, branched, and share a common layer with each other, and at room temperature, when measured at 10 rpm, the Brookfield viscosity of the dispersion is less than 3000 cP.

[0016] The solvent may be aqueous or non-aqueous. The CNS mill base dispersion may further comprise a dispersant. The CNS-derived material may be coated with a binder or be a mixture with a binder. The coating composition may comprise a mill base dispersion and a resin. The resin can be selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, vinyl-chloride copolymer, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyvinyl butyral, polyolefin, and cellulose resin. When the coating composition is tested according to evaluation method A, the resulting cured coating has a surface resistivity of at most 10 7 Ω / square, an L value of at least 30, * or both. When tested according to evaluation method B, the resulting cured coating has a transparency of more than 55% and log 10 (surface resistivity) ≤ 0.005 (transparency) 2It is possible to show a resistivity (Ω / sq) that satisfies -0.52 (transparency) + 19 (where the transparency is given as a percentage). When the coating composition is cured to form a coating, the resulting cured coating may contain 0.10 to 10 wt% of CNS-derived material. The resin can be selected from the group consisting of resins selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyolefin and cellulose resin. The coating composition may further comprise at least one additive selected from the group consisting of titania, hydrophilic fumed silica, hydrophobic fumed silica, hydrophilic precipitated silica, hydrophobic precipitated silica, clay, bentonite, talc, metal carbonate and calcium carbonate, for example titania. Cure the coating composition to at least 55 L * A cured coating having a value of can be prepared.

[0017] In another embodiment, a method of manufacturing a coating composition comprises providing a mill base comprising at least one CNS-derived material dispersed in a solvent, selected from the group consisting of carbon nanostructures, fragments of carbon nanostructures, broken carbon nanotubes, and any combination thereof; and combining the CNS mill base with a resin to form a coating composition, wherein the resulting cured coating has a surface resistivity of at most 10 when the coating composition is tested according to Evaluation Method A 7 Ω / square and a combining step. The carbon nanostructure or fragment of the carbon nanostructure comprises a plurality of multi-layer carbon nanotubes crosslinked in a polymeric structure by branching, intermeshing, entangling, and / or sharing a common layer, and the broken carbon nanotubes are derived from the carbon nanostructure, branched, and share a common layer with each other.

[0018] The mill base may contain CNS-derived materials of 0.5 wt% or less. The resin can be selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, vinyl-chloride copolymer, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyvinyl butyral, polyolefin, and cellulose resin, for example, it can be selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyolefin, and cellulose resin. The solvent may be aqueous or non-aqueous. The mill base may further contain a dispersant. The mill base may have a Brookfield viscosity of less than 3000 cP when measured at room temperature and 10 rpm. When the coating composition is tested according to Evaluation Method B, the resulting cured coating has a transparency of more than 55% and a resistivity (Ω / sq) satisfying log 10 (Surface resistivity) ≤ 0.005 (Transparency) 2 -0.52 (Transparency) + 19 (wherein the transparency is given as a percentage).

[0019] In another embodiment, the cured coating comprises a cured resin and at least one CNS-derived material dispersed in a solvent, the at least one CNS-derived material being selected from the group consisting of carbon nanostructures, fragments of carbon nanostructures, broken carbon nanotubes, and any combination thereof. The carbon nanostructure or the fragment of the carbon nanostructure includes a plurality of multi-layer carbon nanotubes crosslinked in a polymeric structure by being branched, intermeshed, entangled, and / or sharing a common layer, and the broken carbon nanotubes are derived from the carbon nanostructure, branched, and sharing a common layer with each other. The cured coating has a surface resistivity of at most 10 7 Ω / square.

[0020] The cured coating may have an L value of at least 30, at least 40, at least 50, at least 55, at least 60, at least 70, at least 80, at least 90, 30 - 80 or 40 - 70. * The CNS-derived material may be coated with a binder or may be a mixture with a binder. The resin can be selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, vinyl-chloride copolymer, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyvinyl butyral, polyolefin and cellulose resin, and can be selected, for example, from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyolefin and cellulose resin. The cured coating may further contain at least one additive selected from titania, hydrophilic fumed silica, hydrophobic fumed silica, hydrophilic precipitated silica, hydrophobic precipitated silica, clay, bentonite, talc, metal carbonate, calcium carbonate, for example, titania.

[0021] Both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

[0022] The present invention will be described with reference to several figures of the drawings.

Brief Description of the Drawings

[0023]

Figure 1A

Figure 1B

[0024]

Figure 2A

Figure 2B

[0025]

Figure 3A

[0026]

Figure 3B

[0027]

Figure 4

[0028]

Figure 5

DETAILED DESCRIPTION OF THE INVENTION

[0029] In one aspect, the coating composition contains a resin and a carbon nanostructure (CNS) and / or a CNS-derived material at 10 wt% or less on a dry basis, such as 7 wt%, for example 1 wt% to 7 wt%, 2 wt% to 6 wt% or 3 wt% to 5 wt% of the CNS-derived material. The coating composition has an L of at least 30 or at least 55, such as at least 30, at least 40, at least 50, at least 55, at least 60, at least 70, at least 80, at least 90, 30 to 80 or 40 to 70. * represented by. The coating composition can exhibit a surface resistivity of less than 10 7 Ω / square. Certain aspects of the present invention may relate to coating compositions containing a resin and a CNS, fragments of the CNS and / or broken CNTs. Alternatively or in addition, the coating composition may contain a greater amount of CNS and CNS-derived materials, but have an L of less than 55 * .

[0030] Many coatings are applied either as a liquid or a solid. For example, powder coatings are applied as solids, while many coatings are applied as liquids that can then be converted to solids. As used herein, a "liquid coating" is a liquid coating dispersion containing dispersed pigments applied to a substrate. The liquid coating contains a liquid carrier and additional components that can be dissolved, dispersed or suspended therein. Typically, the liquid coating is converted to a solid coating by drying after application to the substrate. A solid coating or "coating" is not a liquid, but may contain a small amount of solvent or other fluid. Any pigment particles in the coating are fixed and do not move freely. The conversion from a liquid coating to a coating may be effected, for example, by evaporation of the solvent and / or polymerization of the resin or other polymeric material. Unlike a millbase that is let down prior to application, the liquid coating is in a state of being applied to the substrate without further dilution.

[0031] Generally, a liquid coating composition comprises a pigment dispersed in a solvent and a binder or curable resin (vehicle). The vehicle for the coating composition of the present invention may be either an aqueous vehicle or a non-aqueous vehicle. Accordingly, the resulting composition may be either an aqueous coating composition or a non-aqueous coating composition.

[0032] The composition of the vehicle can be varied according to the state and requirements of the final coating. For example, the content of the curable resin can be varied from about 70% to 100%. The content of the solvent can be varied from almost 0% to 80%. The non-aqueous solvent may be water-miscible, and the aqueous solvent may contain a water-soluble or water-miscible organic solvent, such as alcohol. The aqueous solvent may contain at least 50 wt% of water, such as at least 60 wt%, at least 70 wt%, at least 80 wt% or at least 90 wt% of water.

[0033] Specific examples of non-aqueous solvents include aromatic hydrocarbons such as xylene, acetate solvents such as butyl acetate and ethyl acetate, aliphatic hydrocarbons, alcohols such as butanol, 1-methyl-2-propanol and methanol, glycols and polyalcohols such as diethylene glycol, ketones such as acetone, cyclohexanone, 2-heptanone, methyl butyl ketone and methyl ethyl ketone, esters such as n-butyl propionate, amides such as dimethylformamide, sulfoxides such as dimethyl sulfoxide, and the like. Further suitable solvents include, but are not limited to, ethyl cellosolve, ethyl cellosolve acetate, ethyl carbitol acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, lactate esters, dimethylacetamide and mixtures of any of the above solvents. It is also possible to mix non-aqueous and aqueous solvents.

[0034] Examples of curable resins or binders useful for either or both of the aqueous and non-aqueous coating compositions of the present invention include, but are not limited to, acrylic, methacrylic, alkyd, polyester, urethane, epoxy, vinyl-chloride copolymer, and cellulose resins. Phenolic resins such as epoxy bisphenol-A or epoxy novolac resins, polystyrene resins, styrene-acrylic resins, polyvinyl butyral, or polyolefin resins can also be used. The binder or curable resin can be cured thermally or by any irradiation source such as ultraviolet irradiation. Similarly, the polymers, oligomers, and monomers in the curable coating composition can also be polymerizable or crosslinkable thermally or by irradiation. For example, oligomers or monomers of these resins or other resins, or polymers such as polyester, acrylate, methacrylate, epoxide, terminal alkene, diisocyanate, diol, diamine, and styrene, can also be included in the uncured coating composition in addition to or instead of the above curable resins. Prepolymers for polyurethanes and polyureas, such as hydroxyl-terminated, amine-terminated, or isocyanate-terminated oligomers, can also be used. In this way, the uncured coating composition can be photosensitive (i.e., curable by irradiation) or thermosensitive (i.e., curable by changing the temperature, e.g., by heating). Alternatively or in addition, the curable coating composition can be cured by removal of the solvent. When the components of the curable coating composition are curable by irradiation, the curable coating composition may further comprise a photoinitiator that generates radicals upon absorption of light.

[0035] Alternatively or in addition, the binder can be used in the form of a dispersion or latex. Such binders may be particularly suitable for aqueous coating systems. For example, the polymeric binder can be a latex of an acrylate or methacrylate copolymer (e.g., NeoCryl® of NSM Neoresins, AC and AS polymers of Alberdingk-Boley), or a water-dispersible polyurethane (e.g., ABU of Alberdingk-Boley) or polyester (e.g., AQ polymer of Eastman Chemical). Polymers that can be used for the binder in an aqueous coating, such as the above polymers, variations, and related materials, are included in the Joncryl® polymers of BASF, the NeoCryl materials of DSM Neoresins, and the AC and AS polymers of Alberdingk-Boley.

[0036] The curable coating composition may further contain optional additives that can be used to improve properties such as viscosity, leveling, and drying time. Examples thereof include co-solvents (especially water-soluble solvents for aqueous coatings), surfactants, dispersants, and fillers such as clay, talc, hydrophilic and hydrophobic fumed and precipitated silica, metal carbonates such as calcium carbonate. In addition, adsorption promoters, flow modifiers, leveling aids, and biocides can also be added. Further pigments, such as titanium oxide, can also be used.

[0037] Specific examples of co-solvents include, but are not limited to, the above materials as solvents, solvents such as acetates, ethyl cellosolve, ethyl cellosolve acetate, butyl cellosolve, butyl cellosolve acetate, ethyl carbitol, ethyl carbitol acetate, diethylene glycol, cyclohexanone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, lactate esters, and mixtures thereof.

[0038] CNS, fragments and / or disrupted CNTs can be used in combination with a dispersant. Generally, the dispersant can promote the dispersion of CNS in a solvent while maintaining a composition viscosity low enough (e.g., 10000 cP at room temperature, e.g., less than 5000 cP, less than 3000 cP, less than 2500 cP, less than 2000 cP, less than 1000 cP or less than 500 cP, e.g., 400 - 3000 cP) to enable practical processing of the composition. The dispersant is selected for its ability to strongly bind to the particles and keep them apart. The dispersant may include surfactants, functionalized polymers and oligomers. The dispersant may be a non-ionic dispersant or an ionic dispersant including both anionic and cationic dispersants. Non-ionic dispersants are preferred and among the ionic dispersants, anionic dispersants are preferred. The dispersant may be amphiphilic and may be polymeric or contain polymeric groups. The dispersant does not include other additives that can be used in aqueous coatings, such as wetting agents, defoamers and co-solvents.

[0039] The concentration of the dispersant in the composition can be varied depending on the composition of the dispersant used and the types and concentrations of the CNS, polymer and solvent. In some embodiments, the concentration of the dispersant is best represented as a weight ratio of dispersant / CNS material. This weight ratio can be, on a weight basis, from no dispersant to up to 5 times (5x) the amount of CNS in the composition, e.g., 0.5x or less, 1x, 2x or less, 3x or less, 4x or less or 0.25x - 5x. However, since relatively small amounts of CNS are required to achieve the resistivity and color provided by the various embodiments herein, even 5x does not result in large amounts of dispersant in the formulated composition.

[0040] Specific examples of the polymeric dispersant include synthetic polymeric dispersants. Suitable groups of molecules that can be included in the dispersant include, but are not limited to, polyalkylene oxides such as polyethylene oxide, polypropylene oxide, and mixtures and copolymers thereof, polyesters such as polycaprolactone, polyvalerolactone, poly(hydroxystearic acid), and poly(hydroxyoleic acid), polyamides such as polycaprolactam, polyacrylates, and block copolymers having hydrophilic and hydrophobic groups. Further examples include amine-functionalized derivatives of any of these (e.g., polyamines, tertiary amine, or quaternary ammonium-functionalized derivatives), such as amine-functionalized or amine-terminated polyalkylene oxides (e.g., Huntsman's Jeffamine dispersants) or acrylic polymers containing amine or acid functional groups. Ethoxylates such as alkylphenol ethoxylates and alkyl ethoxylates are commonly used in aqueous-based formulations as dispersants. Examples include Baker Petrolite's PETROLITE. Related materials and further polymeric additives that can be used for dispersants and additives in aqueous coatings include Evonik's Tego products, Lyondell's Ethacryl products, BASF's Joncryl polymers and EFKA dispersants, Lubrizol's Solsperse TM dispersants, and those included in BYK's Disperbyk® and Byk® dispersants.

[0041] Various rheology modifiers can also be used in combination with the aqueous coating composition to adjust the viscosity of the composition and provide other desirable properties. Suitable compounds include, but are not limited to, water-soluble polymers and copolymers such as gum arabic, whether derivatized or not with ethylene oxide and propylene oxide, polyacrylate salts, polymethacrylate salts, polyvinyl alcohol (Elvanols from Dupont, Celvoline from Celanese), hydroxypropyl cellulose, hydroxyethyl cellulose, polyvinylpyrrolidone (e.g., Luvatec from BASF, Kollidon and Plasdone from ISP, and PVP-K, Glide), polyvinyl ether, starch, polysaccharide, polyethyleneimine and the like.

[0042] Suitable rheology modifiers for the organic coating composition include fumed silica, bentonite, inorganic wax, polyurethane wax and polyalkylene oxide wax.

[0043] When an aqueous coating composition is used, various additives can also be used to control and adjust the pH. Examples of suitable pH adjusters include various amines such as diethanolamine and triethanolamine, and various hydroxide reagents. The hydroxide reagent can be any reagent containing OH - ions, such as a salt having a hydroxide counterion. Examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide and tetramethylammonium hydroxide. Other hydroxide salts, as well as mixtures of hydroxide reagents, can also be used. Further, other alkaline reagents that generate OH - ions in an aqueous medium can also be used. Examples include carbonates such as sodium carbonate, bicarbonates such as sodium bicarbonate, and alkoxides such as sodium methoxide and sodium ethoxide. Buffers can also be added.

[0044] As is known in the art, carbon nanotubes (CNTs or CNTs in the plural) are made up of interconnected sp 2 Carbon nanotubes are carbonaceous materials that contain at least one sheet of hybridized carbon atoms forming a honeycomb lattice that forms a cylindrical or tubular structure. Carbon nanotubes can be single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs). SWCNTs are similar to fullerenes in that they are sp 2 They can be considered as a hybridized carbon allotrope. The structure is a cylindrical tube containing six-membered carbon rings. The similar MWCNTs, on the other hand, have multiple concentric cylindrical tubes. The number of these concentric layers is variable, for example, from 2 to 25 or more. Typically, MWNTs may be 10 nm or more, compared to 0.7 to 20 nm for typical SWNTs.

[0045] In many of the CNSs used in various embodiments, the CNT is, for example, a MWCNT having at least two coaxial carbon nanotubes. The number of layers present can be in the range of, for example, 2 to 30, such as 4 to 30; 6 to 30; 8 to 30; 10 to 30; 12 to 30; 14 to 30; 16 to 30; 18 to 30; 20 to 30; 22 to 30; 24 to 30; 26 to 30; 28 to 30; 2 to 28; 4 to 28; 6 to 28; 8 to 28; 10 to 28; 12 to 28; 14 to 28; 16 to 28; 18 to 28; 20 to 28; 22 to 28; 24 to 28; 26 to 28; 2 to 26; 4 to 26; 6 to 26; 8 to 26; 10 to 26; 12 to 26; 14 to 26; 16 to 26; 18 to 26; 20 to 26; 22 to 26; 24 to 26; 2 to 24; 4 to 24; 6 to 24; 8 to 24; 10 to 24; 12 to 24; 14 to 24; 16 to 24; 18 to 24; 20 to 24; 22 to 24; 2 to 22; 4 to 22; 6 to 22; 8 to 22; 10 to 22; 12 to 22; 14 to 22; 16 to 22; 18 to 22; 20 to 22; 2 to 20; 4 to 20; 6 to 20; 8 to 20; 10 to 20; 12 to 20; 14 to 20; 16 to 20; 18 to 20; 2 to 18; 4 to 18; 6 to 18; 8 to 18; 10 to 18; 12 to 18; 14 to 18; 16 to 18; 2 to 16; 4 to 16; 6 to 16; 8 to 16; 10 to 16; 12 to 16; 14 to 16; 2 to 14; 4 to 14; 6 to 14; 8 to 14; 10 to 14; 12 to 14; 2 to 12; 4 to 12; 6 to 12; 8 to 12; 10 to 12; 2 to 10; 4 to 10; 6 to 10; 8 to 10; 2 to 8; 4 to 8; 6 to 8; 2 to 6; 4 to 6; or 2 to 4 when determined, for example, by a transmission electron microscope (TEM) at a magnification sufficient to analyze the number of layers in a particular case.

[0046] Because the CNS is a polymeric, highly branched, and cross-linked network structure of CNTs, at least some of the chemical structures observed in individual CNTs also apply to the CNS. Additionally, some of the attractive properties often associated with the use of CNTs also appear in materials incorporating the CNS. These include, for example, electrical conductivity, attractive physical properties including maintaining or enabling good tensile strength when incorporated into a silicone-based composition, and thermal and / or chemical stability (sometimes corresponding to diamond crystals or in-plane graphite sheets).

[0047] However, as used herein, the term "CNS" is not synonymous with an individual unentangled structure, such as a "monomeric" fullerene (the term "fullerene" broadly means hollow spherical, ellipsoidal, tubular, such as carbon nanotubes, and other shaped forms of carbon allotropes). In fact, many embodiments of the present invention emphasize the differences and advantages over the use of those CNT building blocks that are observed or expected with the use of the CNS. Without wishing to be bound by a particular interpretation, in the CNS, the combination of branching, cross-linking, and sharing layers between carbon nanotubes is thought to reduce or minimize the van der Waals forces that are often a problem when using individual carbon nanotubes, particularly when it is desirable to prevent aggregation as well.

[0048] In addition to, or instead of, performance characteristics, CNTs that are part of the CNS or derived from the CNS can be characterized by many properties, at least some of which may rely on differentiating them from other nanomaterials, such as normal CNTs (i.e., CNTs that are not derived from the CNS and may be provided as individual, pure, or as-is CNTs).

[0049] In many cases, CNTs present in the CNS or derived from the CNS have typical diameters of 100 nanometers (nm) or less, such as about 5 to about 100 nm, such as about 10 to about 75 nm, about 10 to about 50 nm, about 10 to about 30 nm, about 10 to about 20 nm.

[0050] In certain embodiments, at least one of the CNTs has a length of 2 microns or more as determined by SEM. For example, at least one of the CNTs has a length of 2 to 2.25 microns; 2 to 2.5 microns; 2 to 2.75 microns; 2 to 3.0 microns; 2 to 3.5 microns; 2 to 4.0 microns; 2.25 to 2.5 microns; 2.25 to 2.75 microns; 2.25 to 3 microns; 2.25 to 3.5 microns; 2.25 to 4 microns; 2.5 to 2.75 microns; 2.5 to 3 microns; 2.5 to 3.5 microns; 2.5 to 4 microns; 3 to 3.5 microns; 3 to 4 microns; or 3.5 to 4 microns or more. In some embodiments, more than one, such as at least about 0.1%, at least about 1%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50% or more than half of the CNTs, etc., may have a length of more than 2 microns as determined by SEM, such as within the ranges specified above.

[0051] For many CNTs in the CNS, at least a portion of the lateral layer of the CNT is shared with another CNT. Generally, each carbon nanotube in the CNS does not necessarily have to be branched, cross-linked, or share a common layer with other CNTs, but it is understood that at least some of the CNTs in the carbon nanostructure may interlock with each other and / or with carbon nanotubes that are branched, cross-linked, or share a common layer in the remainder of the carbon nanostructure.

[0052] The form of CNTs present in the CNS, in fragments of the CNS, or in broken CNTs derived from the CNS often typically has a high aspect ratio, with lengths often exceeding 100 times the diameter, and in certain cases even longer. For example, in a CNS (or CNS fragment), the aspect ratio of the length to the diameter of the CNTs can be from about 200 to about 1000, such as 200 - 300; 200 - 400; 200 - 500; 200 - 600; 200 - 700; 200 - 800; 200 - 900; 300 - 400; 300 - 500; 300 - 600; 300 - 700; 300 - 800; 300 - 900; 300 - 1000; 400 - 500; 400 - 600; 400 - 700; 400 - 800; 400 - 900; 400 - 1000; 500 - 600; 500 - 700; 500 - 800; 500 - 900; 500 - 1000; 600 - 700; 600 - 800; 600 - 900; 600 - 1000; 700 - 800; 700 - 900; 700 - 1000; 800 - 900; 800 - 1000; or 900 - 1000.

[0053] In the CNS, as well as in structures derived from the CNS (CNS-derived particles or materials, such as CNS fragments or broken CNTs), at least one of the CNTs is characterized by a particular "branching density". As used herein, the term "branch" refers to the characteristic where a single-walled carbon nanotube branches into a plurality (two or more) and becomes a connected multi-walled carbon nanotube. One embodiment has a certain branching density, according to which, when determined by SEM, there are at least two branches along a 2 micrometer length of the carbon nanostructure. There can also be three or four branches.

[0054] In addition or alternatively, the number of layers observed in the branched regions (dots) in the CNS, fragments of the CNS, or disrupted CNTs is different from one side of the branch (e.g., before the branch point) to the other side of this region (e.g., after or past the branch point). Such a change in the number of layers is also referred to herein as "asymmetry" in the number of layers and is not observed in normal Y-shaped CNTs (the same number of layers is observed in both the region before and after the branch point).

[0055] Diagrams showing these features are provided in FIGS. 1A and 1B. An exemplary Y-shaped CNT 11 not derived from the CNS is shown in FIG. 1A. The Y-shaped CNT 11 includes catalyst particles 13 at or near the branch point 15. Regions 17 and 19 are located before and after the branch point 15, respectively. In the case of a Y-shaped CNT, such as Y-shaped CNT 11, regions 17 and 19 are characterized by the same number of layers, i.e., two layers in the figure.

[0056] In contrast, in the CNS (FIG. 1B), the CNT building block 111 branching at the branch point 115 does not contain catalyst particles at or near this point, as seen in the catalyst-deficient region 113. Further, the number of layers present in the region 117 located forward (or on the first side) before the branch point 115 is different from the number of layers in the region 119 (located behind, rearward, or on the other side with respect to the branch point 115). More specifically, the three-layer feature seen in region 117 is not seen through region 119, causing the above asymmetry (having only two layers in the diagram of FIG. 1B).

[0057] These features are emphasized in the TEM images of FIGS. 2A and 2B.

[0058] More specifically, there are no catalyst particles in the CNS branch in the TEM region 40 of FIG. 2A. In the TEM of FIG. 2B, the first channel 50 and the second channel 52 show the asymmetry in the number of layers characteristic of the branched CNS, while the arrow 54 indicates the region representing layer sharing.

[0059] One, more than one or all of these features may be found in the coating compositions described herein.

[0060] In some embodiments, the CNS exists as a portion of the intertwined and / or interconnected network structure of the CNS. Such an interconnected network structure may contain a bridge between CNSs.

[0061] Suitable techniques for preparing the CNS are described, for example, in U.S. Patent Application Publication No. 2014 / 0093728, issued April 3, 2014, U.S. Patent Nos. 8,784,937, 9,005,755, 9,107,292, and 9,447,259. The entire contents of these documents are incorporated herein by reference.

[0062] As described in these documents, the CNS can be grown on a suitable substrate, for example, on a catalytically treated fibrous material. The product may be a fiber-containing CNS material. In some cases, the CNS is separated from the substrate to form flakes.

[0063] As seen in U.S. Patent Application Publication No. 2014 / 0093728, carbon nanostructures obtained as flake materials (i.e., individual particles having finite dimensions) exist as three-dimensional microstructures due to the entanglement and cross-linking of their highly aligned carbon nanotubes. The aligned morphology reflects the formation of carbon nanotubes on a growth substrate under rapid carbon nanotube growth conditions (e.g., several microns per second, e.g., from about 2 microns per second to about 10 microns per second), thereby inducing the growth of carbon nanotubes substantially perpendicular to the growth substrate. Without being bound by any theory or mechanism, the rapid rate of carbon nanotube growth on the growth substrate may contribute, at least in part, to the complex structural morphology of the carbon nanostructures. Additionally, the bulk density of the CNS can be adjusted to some extent by controlling the growth conditions of the carbon nanostructures, for example, by varying the concentration of transition metal nanoparticle catalyst particles disposed on the growth substrate to initiate the growth of carbon nanotubes.

[0064] For example, the flakes can be further processed by cutting or fluffing (an operation that can include mechanical ball milling, attrition, blending, etc.), chemical treatment, or any combination thereof.

[0065] In some embodiments, the CNS used is "coated" and is also referred to herein as "sized" or "encapsulated" CNS. In a typical sizing process, the coating is applied to the CNTs that form the CNS. The sizing process can form a partial or complete coating non-covalently bound to the CNTs and, in some cases, can act as a binder. Additionally or alternatively, the sizing agent may be applied to a pre-formed CNS in a post-coating (or encapsulation) process. By using a sizing agent with binding properties, for example, CNS can be formed in larger structures, granules or pellets. In other embodiments, the granules or pellets are formed independently of the sizing function.

[0066] The amount of the coating may be variable. For example, relative to the total weight of the coated CNS material, the coating may be from about 0.1 wt% to about 10 wt% (e.g., by weight, about 0.1% to about 0.5%; about 0.5% to about 1%; about 1% to about 1.5%; about 1.5% to about 2%; about 2% to about 2.5%; about 2.5% to about 3%; about 3% to about 3.5%; about 3.5% to about 4%; about 4% to about 4.5%; about 4.5% to about 5%; about 5% to about 5.5%; about 5.5% to about 6%; about 6% to about 6.5%; about 6.5% to about 7%; about 7% to about 7.5%; about 7.5% to about 8%; about 8% to about 8.5%; about 8.5% to about 9%; about 9% to about 9.5%; or about 9.5% to about 10%).

[0067] In many cases, controlling the amount of the coating (or sizing) reduces or minimizes the undesirable effects on the properties of the CNS material itself. For example, a low coating level will likely better maintain the electrical properties brought about by incorporating the CNS or CNS-derived (e.g., CNS fragments of broken CNTs) material into the coating composition.

[0068] Various types of coatings can be selected. In many cases, the sizing solutions commonly used to coat carbon fibers or glass fibers could be utilized to coat the CNS. Specific examples of coating materials include, but are not limited to, fluorinated polymers such as poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), poly(tetrafluoroethylene) (PTFE), polyimide, water-soluble binders such as poly(ethylene) oxide, polyvinyl-alcohol (PVA), cellulose, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone (PVP), and their copolymers and mixtures. In many implementations, the CNS used is treated with polyurethane (PU), thermoplastic polyurethane (TPU), or polyethylene glycol (PEG).

[0069] In some cases, polymers such as epoxy, polyester, vinyl ester, polyetherimide, polyetherketoneketone, polyphthalamide, polyetherketone, polyetheretherketone, polyimide, phenol-formaldehyde, bismaleimide, acrylonitrile-butadiene-styrene (ABS), polycarbonate, polyethyleneimine, polyurethane, polyvinyl chloride, polystyrene, polyolefin, polypropylene, polyethylene, polytetrafluoroethylene, elastomers such as polyisoprene, polybutadiene, butyl rubber, nitrile rubber, ethylene-vinyl acetate polymer, silicone polymer, and fluorosilicone polymer, their combinations, or other polymers or polymer blends, etc., can also be used in some cases. To improve electrical conductivity, conductive polymers such as polyaniline, polypyrrole, and polythiophene can also be used.

[0070] Some implementations utilize coating materials that can assist in stabilizing the dispersion of CNSs in a solvent. In one example, the coating is selected to promote and / or stabilize the dispersion of CNSs in a vehicle produced by combining a desired resin for the coating with a desired solvent and an optional dispersant. Any suitable combination of the resin and solvent provided above can be used. In another example, the coating material is the same as, similar to, or compatible with the dispersant or thickener used when treating the CNSs.

[0071] Many of the embodiments described herein use CNS materials having a CNT purity of 97% or greater. Often, the CNSs used herein do not require additional additives that act against the van der Waals forces.

[0072] The CNSs can be provided in the form of discrete particulate materials (such as CNS flakes, granules, pellets, etc.), or in formulations that further include a liquid medium, such as dispersions, slurries, pastes, or other forms. In many implementations, the CNSs used are separated from their growth substrates.

[0073] In some embodiments, the CNS is provided in the form of flake material after being removed from the growth substrate on which the carbon nanostructure is initially formed. As used herein, the term "flake material" refers to individual particles having finite dimensions. For example, in FIG. 3A, an exemplary depiction of the CNS material after separation of the CNS from the growth substrate is shown. The flake structure 100 may have a first dimension 110 that is from about 1 nm to about 35 μm thick (including any value and any portion therebetween), particularly from 1 nm to about 500 nm thick. The flake structure 100 may have a second dimension 120 that is from about 1 micron to about 750 microns high (including any value and any portion therebetween). The flake structure 100 may have a third dimension 130 that can be from about 1 micron to about 750 microns (including any value and any portion therebetween). Two or all of the dimensions 110, 120, and 130 may be the same or different.

[0074] For example, in some embodiments, the second dimension 120 and the third dimension 130 may independently be on the order of about 1 micron to about 10 microns, about 10 microns to about 100 microns, about 100 microns to about 250 microns, about 250 microns to about 500 microns, or about 500 microns to about 750 microns.

[0075] The CNTs in the CNS range from about 10 nanometers (nm) to about 750 micrometers (μm) or more and have variable lengths. Thus, the CNTs can be 10 nm - 100 nm, 10 nm - 500 nm; 10 nm - 750 nm; 10 nm - 1 micron; 10 nm - 1.25 microns; 10 nm - 1.5 microns; 10 nm - 1.75 microns; 10 nm - 2 microns; 100 nm - 500 nm, 100 nm - 750 nm; 100 nm - 1 micron; 100 - 1.25 microns; 100 - 1.5 microns; 100 - 1.75 microns; 100 - 2 microns; 500 nm - 750 nm; 500 nm - 1 micron; 500 nm - 1 micron; 500 nm - 1.25 microns; 500 nm - 1.5 microns; 500 nm - 1.75 microns; 500 nm - 2 microns; 750 nm - 1 micron; 750 nm - 1.25 microns; 750 nm - 1.5 microns; 750 nm - 1.75 microns; 750 nm - 2 microns; 1 micron - 1.25 microns; 1.0 micron - 1.5 microns; 1 micron - 1.75 microns; 1 micron - 2 microns; 1.25 microns - 1.5 microns; 1.25 microns - 1.75 microns; 1 micron - 2 microns; 1.5 - 1.75 microns; 1.5 - 2 microns; or 1.75 - 2 microns. In some embodiments, at least one of the CNTs has a length of 2 microns or more, such as 4 microns or less, or more, as determined by SEM.

[0076] In FIG. 3B, a SEM image of an exemplary carbon nanostructure obtained as a flake material is shown. The carbon nanostructure shown in FIG. 3B exists as a three-dimensional microstructure due to the entanglement and cross-linking of its highly aligned carbon nanotubes. The aligned form reflects the formation of carbon nanotubes on a growth substrate under rapid carbon nanotube growth conditions (e.g., several microns per second, e.g., about 2 microns per second to about 10 microns per second), thereby inducing the growth of carbon nanotubes substantially perpendicular to the growth substrate. Without being bound by any theory or mechanism, the rapid rate of carbon nanotube growth on the growth substrate may contribute, at least in part, to the complex structural morphology of the carbon nanostructure. In addition, the bulk density of the carbon nanostructure can be adjusted to some extent by adjusting the growth conditions of the carbon nanostructure, for example, by changing the concentration of transition metal nanoparticle catalyst particles disposed on the growth substrate to initiate the growth of carbon nanotubes.

[0077] The flake structure may include carbon nanotubes in the form of a web-like network structure of a carbon nanotube polymer (i.e., "carbon nanopolymer") having a molecular weight of about 15,000 g / mol to about 150,000 g / mol (including all values and any subranges therebetween). In some cases, the upper limit of the molecular weight range may be about 200,000 g / mol, about 500,000 g / mol or about 1,000,000 g / mol, or higher. Higher molecular weights may be associated with dimensionally long carbon nanostructures. The molecular weight may also depend on the diameter of the dominant carbon nanotubes present in the carbon nanostructure and the number of layers of carbon nanotubes. The cross-linking density of the carbon nanostructure is about 2 mol / cm 3 ~ about 80 mol / cm 3It may be. Typically, the cross-linking density depends on the growth density of the carbon nanostructures on the surface of the growth substrate, the growth conditions of the carbon nanostructures, etc. Note that a typical CNS structure containing many CNTs maintained in an open web-like arrangement removes or cancels out the van der Waals forces. This structure can be peeled off more easily, which makes many additional steps of peeling or breaking them into branched structures unique and different from ordinary CNTs.

[0078] In the case of a web-like form, the carbon nanostructures can have a relatively low bulk density, for example, about 0.005 g / cm 3 ~ about 0.1 g / cm 3 or about 0.01 g / cm 3 ~ about 0.05 g / cm 3 can have. As-produced carbon nanostructures can have an initial bulk density of about 0.003 g / cm 3 ~ about 0.015 g / cm 3 . Further integration and / or coating for producing carbon nanostructure flake materials or similar forms can increase the bulk density to about 0.1 g / cm 3 ~ about 0.15 g / cm 3 . In some embodiments, optional further modification of the carbon nanostructures can change the bulk density and / or other properties of the carbon nanostructures. In some embodiments, the bulk density of the carbon nanostructures can be further changed by forming a coating on the carbon nanotubes of the carbon nanostructures and / or by infiltrating the interior of the carbon nanostructures with various materials. Further, the coating of the carbon nanotubes and / or the infiltration of the interior of the carbon nanostructures can adjust the properties of the carbon nanostructures for use in various applications. Further, forming a coating on the carbon nanotubes can desirably facilitate the manipulation of the carbon nanostructures. Further densification can increase the bulk density to an upper limit of about 1 g / cm 3 and, when combined with chemical modification of the carbon nanostructures, the bulk density can be about 1.2 g / cm3 It can be increased to the upper limit of

[0079] In addition to the above flakes, the CNS material can be provided as small grains, pellets or other forms of particulate materials having a typical particle size of about 1 mm to about 1 cm, such as about 0.5 mm to about 1 mm, about 1 mm to about 2 mm, about 2 mm to about 3 mm, about 3 mm to about 4 mm, about 4 mm to about 5 mm, about 5 mm to about 6 mm, about 6 mm to about 7 mm, about 7 mm to about 8 mm, about 8 mm to about 9 mm or about 9 mm to about 10 mm.

[0080] Commercially, an example of a CNS material that can be used is a CNS material developed by Applied Nanostructured Solutions, LLC (ANS) (Massachusetts, United States).

[0081] In some implementations, the CNS is provided in a liquid medium. The liquid medium can be any liquid, solvent suitable for use, for example, with the components of a coating composition. For example, the liquid medium can be the same as the solvent of the vehicle or the resin, or the same as an optional component, such as a co-solvent. Alternatively or in addition, the liquid medium can be miscible or soluble in the solvent of the vehicle or the resin. Different from solutions or dispersions using normal individualized CNTs, such as CNTs in pure form, the CNS can provide a stable dispersion, especially when provided in the form of small grains or pellets as a post-cured CNS. In some embodiments, a stable dispersion can be achieved without a stabilizing surfactant even in an aqueous vehicle. The CNS material can be combined with a liquid by suitable mixing techniques, for example using conventional mixing equipment, optionally in the presence of a dispersant. In certain embodiments, the components are blended to form, for example, a composition, solution or dispersion. The composition can be characterized, for example, by a concentration of CNS in the solvent of about 0.5 wt% or less, such as 0.1 wt% to 0.4 wt% or 0.2 wt% to 0.3 wt%. Alternatively or in addition, a high loading amount, such as about 1 wt% or less, can also be used.

[0082] Unlike solutions or dispersions using normal individualized CNTs, such as CNTs in pure form, CNSs can provide a stable dispersion, especially when provided in the form of small grains or pellets as post-cured CNSs. In some embodiments, a stable dispersion can be achieved without a stabilizing surfactant even when using water as the solvent. Other embodiments utilize a solvent in combination with water during wet processing. Examples of solvents that can be used include, but are not limited to, isopropanol (IPA), methanol, and water.

[0083] In some cases, the techniques used to prepare the dispersion produce CNS-derived species or materials, such as "CNS fragments" and / or "broken CNTs", that are distributed (e.g., uniformly) in an individualized form throughout the dispersion. Apart from the reduced size of the CNS fragments, CNS fragments (a term that includes partially fragmented CNSs) generally have the properties of the as-is CNS and can be identified by electron microscopy and other techniques as described above. Broken CNSs can form when the cross-links between CNTs in the CNS are broken under applied shear. Broken CNTs derived from (generated from or prepared from) the CNS are branched and share a common layer with each other.

[0084] In other embodiments, pelletized, granulated, flaked, or other forms of discrete CNS particles are first dispersed in a liquid medium to produce CNS fragments (including partially fragmented CNSs) and / or broken CNTs. The dispersion can be prepared from starting materials such as uncoated CNSs, PU- or PEG-coated CNSs, or CNSs having any other polymeric binder coating.

[0085] In some cases, the initial CNS is broken down into smaller CNS units or fragments. Except for their reduced size, these fragments generally have the same CNS characteristics and can be identified by electron microscopy and other techniques as described above.

[0086] It is also possible to change the initial nanostructured form of the CNS. For example, the applied shear can break the cross-links between CNTs in the CNS and form CNTs that are typically dispersed as individual CNTs in the electrode composition. It has been found that the structural features of the branched and shared layers are retained for many of these CNTs even after the cross-links are removed. CNSs derived from (prepared from) the CNS and retaining the structural features of the branched and shared layers are referred to herein as "broken" CNTs. These species can impart improved internal connectivity (between CNT units) and result in good conductivity at lower concentrations.

[0087] Thus, compared to coating compositions using normal individual individualized CNTs, such as CNTs in pure form, the coating compositions described herein often contain broken CNTs. These broken CNTs can be easily distinguished from normal carbon nanotubes by standard carbon nanotube analysis techniques, such as SEM. Not all CNTs seen need to be branched and share a common layer, and overall, many of the broken CNTs have these characteristics.

[0088] The CNS used herein can be identified and / or characterized by various techniques. For example, electron microscopes including techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM) can provide information about features such as the specific number frequency of the existing layers, branching, and the absence of catalyst particles. See FIGS. 2A - 2D.

[0089] Raman spectroscopy can show bands associated with impurities. For example, the D band (1350 cm-1 The vicinity) is related to amorphous carbon; the G band (1580 cm -1 The vicinity) is related to crystalline graphite or CNT. The G’ band (2700 cm -1 The vicinity) is expected to occur at approximately twice the frequency of the D band. In some cases, thermogravimetric analysis (TGA) can be used to distinguish between CNS and CNT structures.

[0090] The coating composition can be prepared using any technique known to those skilled in the art. For example, the CNS can be combined with a liquid vehicle and other coating constituents in a high-speed mixer / dissolver, blender or mill, such as a vertical sand mill, horizontal sand mill or bucket sand mill, or other suitable apparatus known to those skilled in the art. Alternatively or in addition, the CNS can be combined with an aqueous or non-aqueous solvent to form a mill base, which is then let down with a resin and any optional further solvent to form a curable coating composition. Optional additives can be part of the mill base or added to the composition during the let-down process. The amount of CNS used can be adjusted to optimize properties such as color, viscosity and resistivity.

[0091] To evaluate the use of a coating composition in the formation of a coating, the following procedure, referred to herein as "Evaluation Method A", can be used to produce a film that can then be tested for resistivity. The coating composition to be tested is applied to a white drawdown chart with a 1-hour air dry and a 4-mil (101.6 μm) drawdown bar and then cured to remove the solvent and produce a cured coating. Suitable curing temperatures and times will be apparent to those skilled in the art and will result in complete removal of any solvent from the coating. For aqueous solvents, a typical curing method is curing at 80°C for 1 hour. For organic solvents, a typical curing method is curing at 138°C for 1 hour. Alternatively or in addition, the following procedure, referred to herein as "Evaluation Method B", can be used to produce a film that can then be tested for both resistivity and transparency. The coating composition to be tested is applied to a transparent polyethylene terephthalate substrate with a 1-hour air dry and a 12-micron drawdown wire and then cured to remove the solvent and produce a cured coating. Suitable curing temperatures and times will be apparent to those skilled in the art and will result in complete removal of any solvent from the coating. For aqueous solvents, a typical curing method is curing at 80°C for 0.5 hour. For organic solvents, a typical curing method is curing at 140°C for 0.5 hour.

[0092] Using several measurable optical elements, a primer coating containing CNS can be evaluated. Color can be classically represented by blackness (L * ), blue / yellow (b * ) and red / green (a * ). 0 L *The value is complete black, while the higher the numerical value, the whiter it is. These values can be measured in the laboratory using equipment such as a Hunter Lab Scan 6000. In certain embodiments, after the preparation of the coating according to Evaluation Method A, the curable coating composition has an L * value of at least 30, for example at least 40, at least 55, at least 60 or at least 70, resulting in a coating. L * can be increased by increasing the amount of white pigment, such as titania, in the coating formulation. For example, the coating composition may have 20-30 wt% titania on a dry basis. Such pigments can increase the L * value to at least 55, for example at least 70, at least 80 or at least 90. Alternatively or in addition, after the preparation of the coating according to Evaluation Method B, the curable coating composition has a transparency of more than 55% and a resistivity (Ω / sq) that satisfies log 10 (surface resistivity) ≤ 0.005(transparency) 2 -0.52(transparency) + 19 (where transparency is given as a percentage), resulting in a coating.

[0093] The coatings provided herein can have a low resistivity. The use of CNS provides high conductivity at low loading levels, enabling the primer coating or base coat to exhibit an extremely low blackness or high transparency. Low blackness facilitates color coating in light colors, such as white or yellow, that do not hide a dark primer at typical thicknesses such as 8-15 microns. High transparency enables the formation of conductive coatings on substrates designed to allow light transmission, such as optical displays and packaging. The coatings provided herein can achieve a surface resistivity of less than 10 7 Ω / square, for example less than 4×10 6 or less than 2.5×10 6 Ω / square, although some transparency may be sacrificed for this purpose. The surface resistivity is 10 5It may be as low as Ω / square. A lower resistivity, for example 10 4 or 10 3 Ω / square or lower can be achieved, but it may result in a darker (i.e., lower L * ) or less transparent coating. A thinner coating, for example 1 mil (25.4 microns) or less, can achieve a surface resistivity of 5×10 10 Ω / sq, for example up to 5×10 9 Ω / sq, up to 5×10 8 Ω / sq, while maintaining a transparency of at least 55%, preferably 60 or 70%, more preferably at least 80%, for example 55% - 80% or 60% - 90%.

[0094] The low resistivity of the CNS - loaded coating also facilitates the downstream coating process. For example, the conductive surface provided by the CNS - loaded coating facilitates electrostatic coating, which cannot be done with non - conductive materials such as plastics. Electrostatic coating is used to coat a grounded surface with charged paint particles from a dedicated gun. The CNS - loaded coating can provide a conductive surface that can ground to a non - conductive substrate.

[0095] Alternatively or in addition, the conductive CNS-loaded coating can facilitate electroplating of non-conductive substrates. For example, a plastic article can be coated with a CNS-loaded primer coating and immersed in a suitable plating bath. Application of an electric current results in a thin layer of metal being deposited on the workpiece. By controlling where the CNS-loaded primer is applied, the metal can be patterned. For example, using standard photolithography techniques, the CNS-loaded primer can be applied to desired locations on the non-conductive substrate. In one embodiment, the workpiece is coated with a photoresist or patterned by suitable irradiation. The CNS-loaded primer is then coated onto the workpiece. Washing the workpiece with a suitable solvent removes those portions of the photoresist that were not exposed to irradiation and also washes those portions of the primer coating. Since the substrate is non-conductive, only those portions of the surface coated with the CNS-loaded primer are electroplated. Other methods of patterned coating known to those skilled in the art can also be used.

[0096] Alternatively or in addition, the CNS-loaded coating can contribute to electromagnetic shielding. Many automotive components are designed to provide EMI shielding for electrical components from external radio signals. Older automobiles with metal bodies performed this function automatically, but the trend towards lightweighting in automotive manufacturing has replaced many of the metal parts with plastic. Additionally, the increased use of electronic and electric components in vehicles, such as keyless ignition, remote starters, electric slide doors and windows, causes an increase in the amount of electromagnetic radiation. On the other hand, vehicles are continuing to incorporate more electrical systems such as GPA navigation systems, entertainment systems, Bluetooth®-enabled devices, hands-free control of cabin features ranging from navigation to entertainment systems, and touch screen control systems, which generate electromagnetic interference (EMI) and are vulnerable to EMI effects. The CNS-loaded primer coating provides automotive and component designers with an additional tool that can enhance the EMI shielding capabilities of the coated parts.

[0097] Alternatively or in addition, the CNS-loaded coating can contribute to the dissipation of static electricity. Antistatic coatings on protective films for displays in televisions and smartphones, as well as on antistatic coatings on packaging trays, carrier tapes, masking films and cover tapes for electronic components, can all benefit from a combination of transparency and low resistivity. Such coatings can also be applied to workbenches or floors to provide static electricity dissipation.

[0098] The present invention is further clarified by the following examples, which are intended to be merely illustrative.

Examples

[0099] Examples 1-9 Several carbon blacks described in Table 1 below, as well as carbon nanostructures coated with polyethylene glycol (Applied Nanostructured Materials, Billerica, Massachusetts), MWCNT (IM299CP, diameter 5 - 15 nm, length less than 50 μm, purity over 99%, ash less than 1%, surface area 280 - 350 m 2 / g, Chengdu Organic Chemical Co., Ltd., Chinese Academy of Sciences) and OCSiAl's TUBALL PD SWCNT (Luxembourg, Luxembourg), a dispersion of 0.4 wt% SWCNT and 0.6 wt% carboxymethyl cellulose in water, were used to prepare a series of mill bases.

Table 1

[0100] According to the formulations in Table 2 below, mill bases were prepared using each of these pigments. Deionized water, BYK - 024 defoamer and dispersant were placed in a plastic tub and stirred at 1500 rpm for 15 minutes. While stirring, the pigment was added, then the stirring speed was increased to 2000 rpm and the mixture was stirred for an additional 15 minutes. For the mill bases of Examples 1 - 7 and 8A, 50 g of the mixture was placed together with 75 g of ZrO beads (1 mm in diameter) and mixed in a LAU DAS200 disperser for 1 hour and filtered. In Example 8B, 50 g of the mixture was placed together with 70 mL of 1 mm diameter ZrO beads and milled in an Eiger mill at 2800 rpm for 3 hours. The fineness of the milling was evaluated using a Hegman grindometer. The viscosity of the mill base was tested at room temperature using a Brookfield DVII+ viscometer, and the particle size distribution was measured using a Horiba HORIBA LA - 950V2 particle size instrument. Table 2

Table 2A

Table 2B

[0101] In the same way, a white mill base was prepared using 31 wt% deionized water, 60 wt% Ti-Pure® R960 titania, 1% AMP95 co-dispersant, 6 wt% DisperBYK-90 dispersant and 2 wt% Dehydran® 1293 defoamer. An acrylic coating formulation was prepared by combining the white mill base with a colored mill base to form a let-down formulation. The components listed in Table 3 were placed into a Dispermat CV-SIP operating at 2000 rpm in the following order: resin, water, colored mill base, white mill base, and then the remaining components with dipropylene-n-butyl ether co-solvent last. The formulation was stirred for 10 minutes. A film was prepared on a BYK-O-CHART panel using a 4 mil (101.6 micron) drawdown bar, air dried for 1 hour, and then cured at 80 °C for 1 hour. For the coating colored with carbon black, the carbon black in the dry coating was approximately 4.57 wt% and the titania content on a dry film basis was approximately 27.4%. For the coating using CNS, the CNS content in the dry coating was approximately 0.24 wt% and the titania content was approximately 29.4%.

Table 3

[0102] The surface resistivity was measured using a Keithley Model 6517B potentiometer equipped with Keithley 8009 test equipment. In a hand-held spectrophotometer X-Rite SP64, CIE's L * a * b * In the color measurement system, color measurements were taken except in the specular reflection mode. The results are shown in Table 4 below.

Table 4

[0103] The data shows that for carbon black, adjusting the formulation is a tool for adjusting the resistivity at a constant filler loading. However, the use of CNS at a fairly low loading provides a fairly bright color while achieving similar conductivity. This can be easily observed in Figure 4, which shows coatings produced using the coating formulations of Comparative Example 3 (left) and Example 6 (right). CNT provides improved color performance (higher L * ) compared to carbon black, but CNT cannot match the electrical performance provided by CNS.

[0104] Example 10 A series of mill bases were prepared using carbon nanostructures coated with polyethylene glycol (Applied Nanostructured Materials, Billerica, Massachusetts), MWCNT (CNTs5, Cabot Performance Materials, Zhuhai, China), and SWCNT (Tuball CNT of OCSiAl).

[0105] The following formulation: deionized water (98.8 wt%), BYK-024 defoamer (0.2 wt%), and dispersants (both 0.4 wt% Dispersogen TC130 dispersant and 0.2 wt% Dispersogen TC93 dispersant from Clariant GmbH) were placed in a plastic beaker and stirred at 1500 rpm for 15 minutes. Accordingly, a mill base (approximately 300 g) was prepared using 0.4 wt% of each pigment. While stirring, the pigments were added, then the stirring speed was increased to 2000 rpm, and the mixture was stirred for an additional 15 minutes. 300 g of the mixture was placed together with 70 mL of ZrO beads (1 mm in diameter) and mixed in a Netzsch Minifer apparatus at 2800 rpm for 6 hours and filtered. The fineness of grind was evaluated using a Hegman grind gauge. The viscosity of the mill base was tested at room temperature on a Brookfield DVII+ viscometer at 10, 50, and 100 rpm (Table 5). The SWCNT dispersion is more viscous than the CNS dispersion.

Table 5

[0106] Coating formulations were prepared by letting down the mill base dispersion according to the formulation in Table 6 (all amounts in grams) to have coating formulations with 0.2%, 0.5%, 1.5% and 6.1% pigments on a dry weight basis. The components were placed into a Dispermat CV-SIP operating at 2000 rpm in the order: resin, water, colored mill base, then the remaining components excluding the dipropylene n-butyl ether co-solvent (the dipropylene n-butyl ether co-solvent was added last). The formulation was stirred for 10 minutes. Coatings were drawndown onto a transparent film (3M's PP2910) using 4 μm and 12 μm bird wire rods, air dried for 1 hour, and cured at 80 °C for 0.5 hour. Electrical measurements were made for Examples 1 - 9 and the transparency of the films was evaluated in a Hunterlab Ultrascan Pro operating at total transmittance with a D65 / 10 light source (Table 7 - 4 micron coatings, Table 8 - 12 micron coatings).

Table 6

[0107] In Figure 5, the surface resistivity is plotted against the transparency (circle = MWCNT, square = CNS, triangle = SWCNT; open symbol = 12 micron coating, filled symbol = 4 micron coating). At lower loadings, the MWCNT-filled coatings had lower resistivity as the loading increased. Generally, the MWCNT-filled coatings had lower resistivity than the corresponding CNS-filled coatings. The performance of the SWCNT coatings was good, but the viscosity of the mill base was higher for the CNS mill base and the fineness of the pigment was coarser.

Table 7

Table 8

[0108] Example 11 Butyl acetate (88.4 g), propylene glycol methyl ether acetate (88.4 g), Setal® 189XX65 (20.0 g) polyester resin and Efka TM PX4310 dispersant (2.4 g) were placed in a paint can and stirred at 1500 rpm for 15 minutes using a Dispermat CV-SIP mixer. While stirring, CNS coated with polyethylene glycol (0.8 g, Applied Nanostructured Materials, Billerica, Massachusetts) was added and then the stirring speed was increased to 2000 rpm for an additional 15 minutes. 300 g of 1 mm zirconium beads were loaded into the can. The paint can was vibrated in a Lau model DAS 200 disperser for 6 hours. The CNS dispersion was then separated from the beads using a 75 micron paint filter. A white titania mill base was prepared in a similar manner except that the paint can was vibrated in the disperser for only 1 hour, using 15.0 wt% Setal® 189XX65 resin, 60.0 wt% Ti-Pure® R960 titania, 9.5 wt% butyl acetate, 9.5 wt% propylene glycol methyl ether acetate and 6.0 wt% DisperBYK-161 dispersant.

[0109] The 0.4 wt% CNS mill base obtained according to the formulation in Table 9 (all amounts in grams) was let down into a polyester resin (Setal® 189XX65 resin from Allnex). The components for each formulation were placed into a Dispermat CV-SIP mixer operating at 2000 rpm in the order: butyl acetate (BuAc), propylene glycol methyl ethyl acetate (PGMEA), resin, colored mill base, then the remaining components. The formulations were stirred for 10 minutes. Films were prepared on a BYK-O-CHART panel using a 4 mil (101.6 micron) drawdown bar, air dried for 1 hour, then cured at 140 °C for 0.5 hour to obtain coatings having a CNS content of about 0.16 wt%. The surface resistivity was measured using a 4-terminal source meter Keithley 2410. For the cured films, at least 5 measurements were made at different positions. The results were recorded in Table 9 below. [Table 9] Table 9

[0110] Example 12 0.4 wt% of the CNS mill base of Example 10 was let down into a polyurethane resin, (NeoRez R-2180 resin from DSM Coating Resins), an acrylic resin, and a blend of PU resin or acrylic resin, together with chlorinated polypropylene (Eastman CP-310W resin) as an adsorption promoter, according to the formulations in Tables 10 and 11 (all amounts in grams). The components for each formulation (60% titania dispersion according to Examples 1 - 9) were put into a Dispermat CV-SIP operating at 2000 rpm in the order: resin, water, colored mill base, then the remaining components excluding the dipropylene n-butyl ether co-solvent (the dipropylene n-butyl ether co-solvent was added last). The formulation was stirred for 10 minutes. A film was prepared on a BYK-O-CHART panel using a 4-mil (101.6 micron) drawdown bar, air-dried for 1 hour, and then cured at 80 °C for 1 hour to obtain a coating having a CNS content of about 0.2 wt%. The surface resistivity was measured using a 4-terminal source meter Keithley 2410. At least 5 measurements were made at different positions on the cured film.

Table 10

Table 11

[0111] Example 13 Dispersant DisperBYK 163 (1 g, BYK Chemie) is mixed with 88.2 g of xylene and 110.3 g of propylene glycol methyl ether acetate. CNS coated with polyethylene glycol (0.5 g, Applied Nanostructured Materials, Billerica, Massachusetts) is mixed with the solvent mixture in a beaker and then loaded into a paint can having 300 g of 1 mm zirconium beads. The paint can is mixed in a Lau model DAS 20 disperser for 6 hours. The CNS dispersion is then separated from the beads using a 75 micron paint filter.

[0112] Wetting agent BYK-346 (0.37 g, BYK Chemie) and Cymel 325 melamine crosslinking agent (6.8 g, 80% active, Allnex) are combined under good stirring. Then, the CNS dispersion and 64 g of Beckosol 12-054 alkyd resin (49 - 51% active, Reichhold) are added and mixed under good stirring until complete incorporation is observed. The resulting coating composition is let down onto a steel panel from ACT Test Panels LLC using a 5 mil (127 micron) wet film applicator. The wet film is air dried at ambient temperature for 10 minutes and cured at 138 °C for 30 minutes. The resulting coating is expected to exhibit excellent electrical conductivity.

[0113] The foregoing description of the preferred embodiments of the present invention has been provided for purposes of illustration and description. It is not intended to limit the invention to the forms disclosed herein in their exact form or to be exhaustive. Changes and variations can be made in light of the above teachings or obtained from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the present invention be defined by the scope of the claims appended hereto and their equivalents. Examples of embodiments of the present invention include the following embodiments. (Appendix 1) A CNS-based dispersion comprising: a solvent; at least one CNS-derived material dispersed in the mill base dispersion at 0.5 wt% or less, the at least one CNS-derived material being selected from the group consisting of carbon nanostructures, fragments of carbon nanostructures, broken carbon nanotubes, and any combination thereof; and the carbon nanostructure or fragment of the carbon nanostructure includes a plurality of multi-walled carbon nanotubes crosslinked in a polymeric structure by being branched, intermeshed, intertwined, and / or sharing a common layer; the broken carbon nanotubes are derived from the carbon nanostructure, are branched, and share a common layer with each other; A CNS-based dispersion having a Brookfield viscosity of the dispersion measured at 10 rpm at room temperature of less than 3000 cP. (Appendix 2) The CNS-based dispersion according to Appendix 1, wherein the solvent is an aqueous solvent containing at least 50% water or an organic solvent. (Appendix 3) The CNS-based dispersion according to Appendix 1 or 2, further comprising a dispersant. (Appendix 4) The CNS-based dispersion according to any one of Appendices 1 to 3, wherein the CNS-derived material is coated with a binder or is a mixture with a binder. (Appendix 5) A coating composition comprising the mill base dispersion according to any one of Appendices 1 to 4 and a resin selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, vinyl-chloride copolymer, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyvinyl butyral, polyolefin, and cellulose resin. (Appendix 6) When tested according to Evaluation Method A, the resulting cured coating has a surface resistivity of 10 7 Ω / square. The coating composition according to Appendix 5. (Appendix 7) When tested according to Evaluation Method A, the resulting cured coating has an L * value of at least 30. The coating composition according to Appendix 5 or 6. (Appendix 8) When tested according to Evaluation Method B, the resulting cured coating has a transparency of more than 55% and a log 10 (Surface resistivity) ≤ 0.005 (Transparency) 2 The coating composition according to any one of Appendices 5 to 7, showing a resistivity (Ω / sq) that satisfies -0.52 (Transparency) + 19 (wherein the transparency is given as a percentage). (Appendix 9) The coating composition according to any one of Appendices 5 to 8, wherein when the coating composition is cured to form a coating, the resulting cured coating contains 0.10 to 10 wt% of CNS-derived material. (Appendix 10) The coating composition according to any one of Appendices 5 to 9, wherein the resin is selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyolefin, and cellulose resin. (Appendix 11) The coating composition according to any one of Appendices 5 to 10, further comprising at least one additive selected from titania, hydrophilic fumed silica, hydrophobic fumed silica, hydrophilic precipitated silica, hydrophobic precipitated silica, clay, bentonite, talc, metal carbonate, and calcium carbonate. (Appendix 12) The coating composition according to any one of Appendices 5 to 11, wherein the additive contains titania. (Appendix 13) A cured coating prepared using the coating composition according to any one of Appendices 5 to 12 and having a value of at least 55 L * . (Appendix 14) A coating composition comprising a resin, at least one CNS-derived material dispersed in the coating composition at 10 wt% or less on a dry basis, the at least one CNS-derived material being selected from the group consisting of carbon nanostructures, fragments of carbon nanostructures, broken carbon nanotubes, and any combination thereof and wherein the carbon nanostructure or fragment of the carbon nanostructure includes a plurality of multi-layer carbon nanotubes crosslinked in a polymeric structure by branching, interlocking, entangling, and / or sharing a common layer with each other and the broken carbon nanotubes are derived from the carbon nanostructure, branched, and share a common layer with each other and when tested according to Evaluation Method A, the resulting cured coating has a surface resistivity of at most 10 7 Ω / square. (Appendix 15) When tested according to Evaluation Method A, the resulting cured coating has at least 30 L * values and is the coating composition according to Supplementary Note 14. (Supplementary Note 16) When tested according to Evaluation Method B, the resulting cured coating has a transparency of more than 55% and a resistivity (Ω / sq) that satisfies log 10 (surface resistivity) ≤ 0.005 (transparency) 2 -0.52 (transparency) + 19 (wherein the transparency is given as a percentage), and is the coating composition according to Supplementary Note 14 or 15. (Supplementary Note 17) The coating composition according to any one of Supplementary Notes 14 to 16, wherein the CNS-derived material is coated with a binder or is a mixture with a binder. (Supplementary Note 18) The coating composition according to any one of Supplementary Notes 14 to 17, wherein the resin is selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, vinyl-chloride copolymer, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyvinyl butyral, polyolefin, and cellulose resin. (Supplementary Note 19) The coating composition according to any one of Supplementary Notes 14 to 17, wherein the resin is selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyolefin, and cellulose resin. (Supplementary Note 20) The coating composition according to any one of Supplementary Notes 14 to 19, further comprising at least one additive selected from titania, hydrophilic fumed silica, hydrophobic fumed silica, hydrophilic precipitated silica, hydrophobic precipitated silica, clay, bentonite, talc, metal carbonate, and calcium carbonate. (Supplementary Note 21) A cured coating produced by curing the coating composition according to any one of Supplementary Notes 14 to 20 and containing 0.01 wt% to 10 wt% of the CNS-derived material. (Supplementary Note 22) Furthermore, it contains 20 to 30 wt% of titania and has at least 55 L * values, and is the cured coating according to Supplementary Note 21. (Supplementary Note 23) A method for producing a coating composition, Providing a mill base comprising at least one CNS-derived material selected from the group consisting of a carbon nanostructure, a fragment of a carbon nanostructure, a broken carbon nanotube, and any combination thereof, dispersed in a solvent, wherein the carbon nanostructure or fragment of a carbon nanostructure comprises a plurality of multi-walled carbon nanotubes crosslinked in a polymeric structure by branching, intermeshing, entangling, and / or sharing a common layer, the broken carbon nanotubes are derived from the carbon nanostructure, branched, and share a common layer with each other, when the CNS mill base is combined with a resin and tested according to Evaluation Method A, the resulting cured coating has a surface resistivity of at most 10 7 forming a coating composition having a surface resistivity of Ω / square A method comprising. (Appendix 24) The method according to Appendix 23, wherein the mill base comprises 0.5 wt% or less of a CNS-derived material. (Appendix 25) The method according to Appendix 23 or 24, wherein the resin is selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, vinyl-chloride copolymer, phenol, epoxy bisphenol-A, epoxy novolak, polystyrene resin, styrene-acrylic resin, polyvinyl butyral, polyolefin, and cellulose resin. (Appendix 26) The method according to Appendix 23 or 24, wherein the resin is selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, phenol, epoxy bisphenol-A, epoxy novolak, polystyrene resin, styrene-acrylic resin, polyolefin, and cellulose resin. (Appendix 27) The method according to any one of Appendices 23 to 26, wherein the solvent is an aqueous solvent containing at least 50 wt% of water or an organic solvent. (Appendix 28) The method according to any one of Appendices 23 to 27, wherein the mill base has a Brookfield viscosity of less than 3000 cP when measured at room temperature at 10 rpm. (Appendix 29) The method according to any one of Appendices 23 to 28, wherein the mill base further comprises a dispersant. (Appendix 30) When the coating composition is tested according to Evaluation Method B, the resulting cured coating has a transparency of more than 55% and log 10 (Surface resistivity) ≦ 0.005 (Transparency) 2 The resistivity (Ω / sq) that satisfies -0.52 (transparency) + 19 (where the transparency is given as a percentage), and the method according to any one of paragraphs 23 to 29 of the appended text.

Claims

1. A coating composition comprising a CNS mill base dispersion and a resin, wherein the CNS mill base dispersion comprises a solvent, a dispersant, at least one CNS-derived material dispersed in the mill base dispersion at 0.5 wt% or less, the at least one CNS-derived material being selected from the group consisting of carbon nanostructures, fragments of carbon nanostructures, broken carbon nanotubes, and any combination thereof and the carbon nanostructure or fragment of a carbon nanostructure comprises a plurality of multi-walled carbon nanotubes crosslinked in a polymeric structure by being branched, intermeshing, intertwining, and / or sharing a common layer, the broken carbon nanotubes are derived from the carbon nanostructure, are branched, and share a common layer with each other, at room temperature, the Brookfield viscosity of the dispersion measured at 10 rpm is less than 3000 cP, the coating composition A) when cured to produce a cured coating by applying to a white drawdown chart with a 4 mil (101.6 μm) drawdown bar, air drying for 1 hour, and then removing the solvent and curing, the resulting cured coating has a maximum surface resistivity of 10 ７ Ω / square and an L ＊ value of at least 30, or B) when cured to produce a cured coating by applying to a transparent polyethylene terephthalate substrate with a 12 micron drawdown wire, air drying for 1 hour, and then removing the solvent and curing, the resulting cured coating has a transparency of greater than 55% and a resistivity (Ω / sq) that satisfies log １０ (surface resistivity) ≤ 0.005 (transparency) ２ -0.52 (transparency) + 19 (where transparency is given as a percentage), either a coating composition.

2. The coating composition according to claim 1, wherein the solvent is an aqueous solvent containing at least 50% water or an organic solvent.

3. The coating composition according to claim 1, wherein the resin is selected from the group consisting of acrylic, methacrylic, alkyd, polyester, urethane, epoxy, vinyl-chloride copolymer, phenol, epoxy bisphenol-A, epoxy novolac, polystyrene resin, styrene-acrylic resin, polyvinyl butyral, polyolefin and cellulose resin.

4. The coating composition according to any one of claims 1 to 3, wherein when the coating composition is cured to form a coating, the resulting cured coating contains 0.10 to 10 wt% of CNS-derived material.

5. The coating composition according to claim 4, further comprising at least one additive selected from titania, hydrophilic fumed silica, hydrophobic fumed silica, hydrophilic precipitated silica, hydrophobic precipitated silica, clay, bentonite, talc, metal carbonate and calcium carbonate.

6. A cured coating produced by curing the coating composition according to claim 4, further containing 20 to 30 wt% of titania and having a value of at least 55 L ＊ thereof.

7. A method for producing a coating composition, comprising: providing a mill base comprising at least one CNS-derived material dispersed in a solvent, selected from the group consisting of carbon nanostructures, fragments of carbon nanostructures, broken carbon nanotubes, and any combination thereof, and a dispersant, wherein the at least one CNS-derived material is 0.5 wt% or less; wherein the carbon nanostructure or fragment of the carbon nanostructure comprises a plurality of multi-walled carbon nanotubes crosslinked in a polymeric structure by being branched, intermeshed, intertwined, and / or sharing a common layer; The step in which the broken carbon nanotubes are derived from the carbon nanostructure, branched, and share a common layer with each other; The step of combining the milbase with a resin to form a coating composition, wherein the coating composition A) When applied to a white drawdown chart with a 4 mil (101.6 μm) drawdown bar, air-dried for 1 hour, and then cured to remove the solvent to produce a cured coating, the resulting cured coating has a maximum surface resistivity of 10 ７ Ω / square and an L of at least 30 ＊ or B) When applied to a transparent polyethylene terephthalate substrate with a 12 micron drawdown wire, air-dried for 1 hour, and then cured to remove the solvent to produce a cured coating, the resulting cured coating has a transparency of more than 55% and log １０ (surface resistivity) ≤ 0.005(transparency) ２ -0.52(transparency) + 19 (wherein the transparency is given as a percentage) and a resistivity (Ω / sq) satisfying either condition; A method comprising: **Claim 8** The method according to claim 7, wherein the solvent is an aqueous solvent containing at least 50 wt% water or an organic solvent. **Claim 9** The method according to claim 7, wherein the milbase has a Brookfield viscosity of less than 3000 cP when measured at room temperature at 10 rpm.

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