Aqueous dispersions

Abstract

Conductive aqueous dispersions for use as coating applications and methods of producing conductive aqueous dispersions are provided. In one embodiment, a method of producing an electrically conductive aqueous dispersion includes mixing water, a solvent, and a binder to form a homogeneous mixture. In addition, the method includes adding carbon nanotubes to the homogeneous mixture and mixing under high shear to form a dispersion.

Description

Technical Field

[0001] The present technical field generally relates to aqueous dispersions, and more particularly to conductive aqueous dispersions containing carbon nanotubes or their use as coatings. Background Art

[0002] Conductive coatings are typically formed on non-conductive substrates using either dry or wet processes. In dry processes, metal oxide-based conductive coatings are formed using physical vapor deposition (PVD) (including sputtering, ion plating, and vacuum deposition) or chemical vapor deposition (CVD). In wet processes, conductive coating compositions are formed using dispersions of mixed oxide conductive powders and a binder.

[0003] A major discovery and improvement in the production of conductive inks, dyes, and coatings has been the discovery and improvement of carbon nanotubes, which are essentially single layers of graphite rolled into tubes, either single-walled nanotubes, double-walled nanotubes (DWNTs), or multi-walled nanotubes (MWNTs) rolled into multiple concentric cylindrical layers. Carbon nanotubes are easy to synthesize and commercially available. They have good intrinsic electrical conductivity and have been used to form conductive materials.

[0004] It would be desirable to provide coatings or paints having enhanced qualities, such as those suitable for use on automobiles or other vehicles. In particular, it would be desirable to provide coatings or paints having low resistivity. Furthermore, it would be desirable to form an aqueous dispersion of binder and carbon nanotubes having a composition suitable for spraying onto automotive body parts. Summary of the Invention

[0005] The present invention provides a conductive aqueous dispersion for use as a coating and a method for producing the conductive aqueous dispersion. In one embodiment, the method for producing the conductive aqueous dispersion comprises mixing water, a solvent, and a binder to form a homogeneous mixture. Furthermore, the method comprises adding carbon nanotubes to the homogeneous mixture and mixing under high shear to form a dispersion.

[0006] In another embodiment, a conductive aqueous dispersion is provided. The aqueous dispersion comprises water, a solvent, a binder, and carbon nanotubes. In the aqueous dispersion, the carbon nanotubes are conductive, and the dispersion comprises from about 5% to about 20% of the conductive material based on the total binder solids.

[0007] This summary is intended to introduce some concepts in a simplified form that will be further described in the detailed description below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. DETAILED DESCRIPTION

[0008] The following detailed description is merely illustrative and is not intended to limit the compositions and methods described herein. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or in the following detailed description.

[0009] Unless otherwise indicated, as used herein, "a", "an" or "said / the" means one (kind) or more (kinds). The term "or" can be conjunction or disjunction. Open terms such as "include", "including", "contain", "containing", etc. mean "comprising". In certain embodiments, the numerical values ​​expressing amounts, material ratios, material physical properties and / or uses in this specification can be understood to be modified by the word "about". The term "about" used in conjunction with numerical values ​​and claims indicates an accuracy interval familiar to and accepted by those skilled in the art. Typically, this accuracy interval is ±10%. All numerical values ​​expressing amounts, material ratios, material physical properties and / or uses in this specification can be understood to be modified by the word "about", or can be understood to be not modified by the word "about". As described herein, unless otherwise indicated, the "%" or "percentage" described in this disclosure refers to weight percentage.

[0010] As noted above, provided herein are electrically conductive aqueous dispersions for application as coatings or paints to substrates such as automotive body parts. Exemplary aqueous dispersions comprise electrically conductive carbon nanotubes.

[0011] Example

[0012] Comparative Example 1

[0013] A four-liter reactor was equipped with a steel propeller mixer and filled with deionized (DI) water (60%), ethylene glycol monobutyl ether (3.08%), heavy naphtha (1.37%), and dipropylene glycol monobutyl ether (1.37%). While mixing (at a temperature of 20 to 25°C), the solid resin, binder, and additives (except CNTs) were slowly added to the solvent and homogenized for an additional thirty minutes under moderate shear. After the binder was fully homogenized, the homogenous mixture was transferred to a high-shear disperser equipped with a stainless steel sawtooth propeller. The conductive dispersion was then produced by adding 1.13% carbon nanotubes (CNTs) under high shear and mixing for approximately forty-five minutes to form the resulting dispersion.

[0014] Table A - Comparative Example 1

[0015] Components parts by weight Deionized water 60.00 Ethylene glycol monobutyl ether 3.08 Heavy naphtha 1.37 Dipropylene glycol monobutyl ether 1.37 Acrylic resin (Example 1 of US 7,825,173) 11.43 Polyester resin (Example 5 of US10,233,353) --- Polyurethane resin (Example 2a of US 9,688,877) 10.37 Melamine-formaldehyde resin 3.41 amine 0.14 magnesium silicate 7.36 defoaming agent 0.34 carbon nanotubes 1.13 total 100.00 % Conductive Material Based on Binder Solids 10

[0016] Comparative Example 2

[0017] The four-liter reactor is equipped with a steel propeller A stirring mixer was charged with deionized water (61.21%), ethylene glycol monobutyl ether (2.94%), heavy naphtha (1.31%), and dipropylene glycol monobutyl ether (1.31%). While mixing (at a temperature of 20 to 25°C), the solid resin, binder, and additives (except CNTs) were slowly added to the solvent and homogenized for an additional 30 minutes under moderate shear. After the binder was fully homogenized, the homogenous mixture was transferred to a high-shear disperser equipped with a stainless steel sawtooth propeller. A conductive dispersion was then produced by adding 1.63% carbon nanotubes (CNTs) under high shear mixing and mixing the resulting dispersion for approximately 45 minutes.

[0018] Table B - Comparative Example 2

[0019] Components parts by weight Deionized water 61.21 Ethylene glycol monobutyl ether 2.94 Heavy naphtha 1.31 Dipropylene glycol monobutyl ether 1.31 Acrylic resin (Example 1 of US 7,825,173) 10.93 Polyester resin (Example 5 of US10,233,353) --- Polyurethane resin (Example 2a of US 9,688,877) 9.92 Melamine-formaldehyde resin 3.26 amine 0.13 magnesium silicate 7.03 defoaming agent 0.33 carbon nanotubes 1.63 total 100.00 % Conductive Material Based on Binder Solids 15

[0020] Example 3

[0021] A four-liter reactor was equipped with a steel propeller mixer and charged with deionized water (60.62%), ethylene glycol monobutyl ether (3.07%), heavy naphtha (1.37%), and dipropylene glycol monobutyl ether (1.37%). While mixing (at a temperature of 20 to 25°C), the solid resin, binder, additives, and experimental polyester resin #1 (excluding CNTs) were slowly added to the solvent and homogenized for an additional thirty minutes under moderate shear. After the binder was fully homogenized, the homogenous mixture was transferred to a high-shear disperser equipped with a stainless steel sawtooth propeller. A conductive dispersion was then produced by adding 1.14% carbon nanotubes (CNTs) under high shear mixing and mixing the resulting dispersion for approximately forty-five minutes.

[0022] Table C - Example 3

[0023] Components parts by weight Deionized water 60.62 Ethylene glycol monobutyl ether 3.07 Heavy naphtha 1.37 Dipropylene glycol monobutyl ether 1.37 Acrylic resin (Example 1 of US 7,825,173) 11.41 Polyester resin (Example 5 of US10,233,353) 2.86 Polyurethane resin (Example 2a of US 9,688,877) 6.93 Melamine-formaldehyde resin 3.40 amine 0.14 magnesium silicate 7.35 defoaming agent 0.34 carbon nanotubes 1.14 total 100.00 % Conductive Material Based on Binder Solids 10

[0024] Example 4

[0025] A four-liter reactor was equipped with a steel propeller mixer and charged with deionized water (61.77%), ethylene glycol monobutyl ether (2.94%), heavy naphtha (1.31%), and dipropylene glycol monobutyl ether (1.31%). While mixing (at a temperature of 20 to 25°C), the solid resin, binder, additives, and experimental polyester resin #1 (excluding CNTs) were slowly added to the solvent and homogenized under moderate shear for an additional thirty minutes. After the binder was fully homogenized, the homogenous mixture was transferred to a high-shear disperser equipped with a stainless steel sawtooth propeller. A conductive dispersion was then produced by adding 1.14% carbon nanotubes (CNTs) under high shear mixing and mixing the dispersion for approximately forty-five minutes.

[0026] Table D - Example 4

[0027]

[0028]

[0029] For Comparative Examples 1-2 and Examples 3-4, the binder solids content was measured using a ComputracMAX 4000xL available from Ametek of Brookfield, USA, following the procedure of ASTM D7232-06.

[0030] As noted, the acrylic resin component is defined in Example 1 of US Patent No. 7,825,173, which is incorporated herein by reference in its entirety. In the examples herein, the total solids content of the acrylic resin component is 46.3%.

[0031] As noted, the polyester resin component is defined in Example 5 of US Patent No. 10,233,353, which is incorporated herein by reference in its entirety. In the examples herein, the polyester resin component has a total solids content of 43.7%.

[0032] As noted, the polyurethane resin component is defined in Example 2a of US Patent No. 9,688,877, which is incorporated herein by reference in its entirety. In the examples herein, the polyurethane resin component has a total solids content of 35.3%.

[0033] The surface resistivity of the coated articles formed with the coatings from Examples 1-4 was analyzed for comparison. Specifically, the surface resistivity of the four coated articles was measured using a "Prostat PRS-801 Resistance System" (Prostat, Inc., Glendale Heights, IL, USA) following the procedure of ASTM D4496, which is used to determine the resistivity or conductivity of materials that are generally classified as moderately conductive and are neither good electrical insulators nor good conductors. In ASTM D4496, test measurements of resistivity (or conductivity) and sample geometry data are used to calculate the resistivity of the material. This test method is applicable to all materials with a surface resistivity in the range of 103 to 107 Ω / □. This test method is designed for measurements made under standard conditions of 23°C and 50% relative humidity, but its operating principles can be applied to samples measured at lower or higher temperatures and relative humidities.

[0034] Table E shows the surface resistivity test results of articles formed with the coatings from Examples 1-4:

[0035] Table E Surface resistivity measured according to ASTM D4496

[0036]

[0037] Surface resistivity is the resistance to leakage current along the surface of an insulating material. As shown, articles coated with the compositions of Examples 3 and 4 exhibit improved surface resistivity (lower values ​​indicate better resistivity).

[0038] Examples 1-4 had the following estimated compositions.

[0039] Table F - Composition

[0040]

[0041] Example 5

[0042] A four-liter reactor was equipped with a steel propeller mixer and filled with deionized water (74.26%), dipropylene glycol methyl ether (0.58%), dipropylene glycol monobutyl ether (0.58%), heavy naphtha (0.73%), and diethylene glycol monobutyl ether (0.35%). While mixing (at a temperature of 20 to 25°C), the solid resin, binder, and additives (except CNTs) were slowly added to the solvent and homogenized for an additional 30 minutes under moderate shear. After the binder was fully homogenized, the homogenous mixture was transferred to a high-shear disperser equipped with a stainless steel sawtooth propeller. The conductive dispersion was then produced by adding 1.13% carbon nanotubes (CNTs) under high shear and mixing for approximately 45 minutes.

[0043] Table G - Example 5

[0044]

[0045]

[0046] Example 6

[0047] A four-liter reactor was equipped with a steel propeller mixer and filled with deionized water (74.78%), dipropylene glycol methyl ether (0.56%), dipropylene glycol monobutyl ether (0.56%), heavy naphtha (0.70%), and diethylene glycol monobutyl ether (0.34%). While mixing (at a temperature of 20 to 25°C), the solid resin, binder, and additives (except CNTs) were slowly added to the solvent and homogenized for an additional thirty minutes under moderate shear. After the binder was fully homogenized, the homogenous mixture was transferred to a high-shear disperser equipped with a stainless steel sawtooth propeller. The conductive dispersion was then produced by adding 1.63% carbon nanotubes (CNTs) under high shear mixing and mixing the resulting dispersion for approximately forty-five minutes.

[0048] Table H - Example 6

[0049]

[0050]

[0051] Example 7

[0052] A four-liter reactor was equipped with a steel propeller mixer and charged with deionized water (74.00%), dipropylene glycol methyl ether (0.55%), dipropylene glycol monobutyl ether (0.55%), heavy naphtha (0.69%), and diethylene glycol monobutyl ether (0.33%). While mixing (at a temperature of 20 to 25°C), the solid resin, binder, and additives (except CNTs) were slowly added to the solvent and homogenized for an additional thirty minutes under moderate shear. After the binder was fully homogenized, the homogenous mixture was transferred to a high-shear disperser equipped with a stainless steel sawtooth propeller. The conductive dispersion was then produced by adding 1.17% carbon nanotubes (CNTs) under high shear mixing and mixing the resulting dispersion for approximately forty-five minutes.

[0053] Table I - Example 7

[0054]

[0055] Example 8

[0056] A four-liter reactor was equipped with a steel propeller mixer and filled with deionized water (74.55%), dipropylene glycol methyl ether (0.52%), dipropylene glycol monobutyl ether (0.52%), heavy naphtha (0.66%), and diethylene glycol monobutyl ether (0.32%). While mixing (at a temperature of 20 to 25°C), the solid resin, binder, and additives (except CNTs) were slowly added to the solvent and homogenized for an additional thirty minutes under moderate shear. After the binder was fully homogenized, the homogenous mixture was transferred to a high-shear disperser equipped with a stainless steel sawtooth propeller. The conductive dispersion was then produced by adding 1.68% carbon nanotubes (CNTs) under high shear mixing and mixing the resulting dispersion for approximately forty-five minutes.

[0057] Table J - Example 8

[0058]

[0059] For Examples 5-8, binder solids content was measured using a Computrac MAX 4000xL available from Ametek of Brookfield, USA, following the procedure of ASTM D7232-06.

[0060] Table K gives the surface resistivity test results for articles formed with the coatings from Examples 5-8:

[0061] Table K Surface resistivity measured according to ASTM D4496

[0062]

[0063] The performance of Examples 5-8 on coated articles was evaluated. For example, surface resistivity was measured using the "PROSTAT PRS-801 RESISTANCE SYSTEM" (PROSTAT CORPORATION, USA) following the ASTM D4496 procedure. Surface resistivity is the resistance to leakage current along the surface of an insulating material. Lower values ​​indicate better coating performance, depending on the test parameters.

[0064] Examples 5-8 have the following estimated compositions.

[0065] Table L - Composition

[0066]

[0067] carbon nanotubes

[0068] The carbon nanotubes are provided in the form of solid materials such as pellets and mixed into the composition. Exemplary carbon nanotubes are branched and cross-linked carbon structures with a conductive coating. Exemplary carbon nanotube pellet dimensions are 5 mm in length, 1 mm in diameter, and have a bulk density of 0.135 g / cm 3 (ASTM D 7481), with a surface area of ​​200 m 2 / g (ASTM D 6556), with a carbon content of 97%. Exemplary carbon nanotubes are available from Cabot Corporation in Boston, Massachusetts under the trademark Athlos TM Purchased.

[0069] In exemplary embodiments, the aqueous dispersion has a total carbon nanotube content of at least 0.1 wt %, such as at least 0.5 wt %, for example at least 0.6 wt %, such as at least 0.7 wt %, for example at least 0.8 wt %, such as at least 0.9 wt %, for example at least 1.0 wt %, such as at least 1.1 wt %, for example at least 1.2 wt %, such as at least 1.3 wt %, for example at least 1.4 wt %, such as at least 1.5 wt %, for example at least 1.6 wt %, such as at least 1.7 wt %, for example at least 1.8 wt %, such as at least 1.9 wt %, for example at least 2.0 wt %. Exemplary aqueous dispersions have a total carbon nanotube content of at most 5 wt%, such as at most 2.5 wt%, for example at most 2.4 wt%, such as at most 2.3 wt%, for example at most 2.2 wt%, such as at most 2.1 wt%, for example at most 2.0 wt%, such as at most 1.9 wt%, for example at most 1.8 wt%, such as at most 1.7 wt%, for example at most 1.6 wt%, such as at most 1.5 wt%, for example at most 1.4 wt%, such as at most 1.3 wt%, for example at most 1.2 wt%, such as at most 1.1 wt%, for example at most 1.0 wt%.

[0070] In an exemplary embodiment, carbon nanotubes are the sole source of conductive material in the aqueous dispersion. Based on binder solids, exemplary aqueous dispersions have a conductive material content of at least 5 wt %, such as at least 6 wt %, for example at least 7 wt %, such as at least 8 wt %, for example at least 9 wt %, such as at least 10 wt %, for example at least 11 wt %, such as at least 12 wt %, for example at least 13 wt %, such as at least 14 wt %, for example at least 15 wt %. Based on binder solids, exemplary aqueous dispersions have a conductive material content of at most 25 wt %, such as at most 20 wt %, for example at most 19 wt %, such as at most 18 wt %, for example at most 17 wt %, such as at most 16 wt %, for example at most 15 wt %, such as at most 14 wt %, for example at most 13 wt %, such as at most 12 wt %, for example at most 11 wt %, such as at most 10 wt %, for example at most 9 wt %, such as at most 8 wt %. As described herein, binder solids may be measured following the procedure of ASTM D7232-06.

[0071] water

[0072] In an exemplary embodiment, the aqueous dispersion has a total water content of at least 40% by weight, such as at least 45% by weight, for example at least 50% by weight, such as at least 52.5% by weight, for example at least 55% by weight, such as at least 57.5% by weight, for example at least 60% by weight, such as at least 62.5% by weight, for example at least 65% by weight. Exemplary aqueous dispersions have a total water content of at most 75% by weight, such as at most 70% by weight, for example at most 65% by weight, such as at most 60% by weight, for example at most 55% by weight, such as at most 50% by weight, for example at most 45% by weight, such as at most 40% by weight, for example at most 35% by weight, such as at most 30% by weight, for example at most 25% by weight.

[0073] solvent

[0074] In an exemplary embodiment, the aqueous dispersion has a total solvent content of at least 2% by weight, such as at least 2.5% by weight, for example at least 3% by weight, such as at least 3.5% by weight, for example at least 4% by weight, such as at least 4.5% by weight, for example at least 5% by weight, such as at least 5.5% by weight, for example at least 6% by weight. Exemplary aqueous dispersions have a solvent content of at most 10% by weight, such as at most 8% by weight, for example at most 7.5% by weight, such as at most 7% by weight, for example at most 6.5% by weight, such as at most 6% by weight, for example at most 5.5% by weight, such as at most 5% by weight, for example at most 4.5% by weight, such as at most 4% by weight.

[0075] The aqueous dispersion may contain conventional organic solvents. Examples of such solvents are alcohols, such as propanol, butanol, hexanol, 2-ethylhexanol, benzyl alcohol, isodecyl alcohol; glycol ethers, such as diethylene glycol di-C1-C6-alkyl ether, dipropylene glycol di-C1-C6-alkyl ether, ethoxypropanol, methoxypropanol, butyl glycol, butoxypropanol, butyl diglycol, hexyl glycol, methoxybutanol; glycol ether esters, such as methoxypropyl acetate, butyl glycol acetate, butyl diglycol acetate; glycols, such as ethylene glycol and / or propylene glycol, and dimers or trimers thereof; ketones, such as methyl ethyl ketone, methyl isobutyl ketone, acetone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone; terpenes, aromatic or aliphatic hydrocarbons, such as toluene, xylene, or linear or branched aliphatic C6-C12 hydrocarbons.

[0076] Exemplary solvents include ethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and heavy naphtha, although other suitable solvents may also be used.

[0077] Binder

[0078] In exemplary embodiments, the aqueous dispersion has a total binder content of at least 10 wt %, such as at least 11 wt %, for example at least 12 wt %, such as at least 13 wt %, for example at least 14 wt %, such as at least 15 wt %, for example at least 16 wt %, such as at least 17 wt %, for example at least 18 wt %, such as at least 19 wt %, for example at least 20 wt %, such as at least 21 wt %, for example at least 22 wt %, such as at least 23 wt %, for example at least 24 wt %, such as at least 25 wt %, for example at least 26 wt %, such as at least 27 wt %, for example at least 28 wt %, such as at least 29 wt %, for example at least 30 wt %. In an exemplary embodiment, the aqueous dispersion has a total binder content of at most 35 wt %, such as at most 34 wt %, for example at most 33 wt %, such as at most 32 wt %, for example at most 31 wt %, such as at most 30 wt %, for example at most 29 wt %, such as at most 28 wt %, for example at most 27 wt %, such as at most 26 wt %, for example at most 25 wt %, such as at most 24 wt %, for example at most 23 wt %, such as at most 22 wt %, for example at most 21 wt %, such as at most 20 wt %, for example at most 19 wt %, such as at most 18 wt %, for example at most 17 wt %, such as at most 16 wt %, for example at most 15 wt %.

[0079] In an exemplary embodiment, the binder includes a variety of different resins. For example, the aqueous dispersion may include acrylic resins, polyester resins, polyurethane resins, acrylic / (meth)acrylic acid-based copolymer hybrid resins and / or polyurethane polyester / (meth)acrylic acid-based copolymer hybrid resins and mixtures thereof.

[0080] Acrylic resin

[0081] One exemplary binder is an acrylic resin, such as that produced according to Example 1 of US Patent No. 7,825,173.

[0082] In an exemplary embodiment, the aqueous dispersion has a total acrylic resin content of at least 2.5 wt%, such as at least 5 wt%, for example at least 6 wt%, such as at least 7 wt%, for example at least 8 wt%, such as at least 9 wt%, for example at least 10 wt%, such as at least 10.5 wt%, for example at least 11 wt%, such as at least 11.5 wt%, for example at least 12 wt%. In an exemplary embodiment, the aqueous dispersion has a total acrylic resin content of at most 20 wt%, such as at most 15 wt%, for example at most 14.5 wt%, such as at most 14 wt%, for example at most 13.5 wt%, such as at most 13 wt%, for example at most 12.5 wt%, such as at most 12 wt%, for example at most 11.5 wt%, such as at most 11 wt%, for example at most 10.5 wt%, such as at most 10 wt%, for example at most 8 wt%, such as at most 5 wt%.

[0083] Certain embodiments herein have at least 2%, such as at least 2.5%, at least 3%, at least 3.5%, at least 4%, at least 4.5%, at least 5%, at least 5.5%, at least 6%, at least 6.5%, at least 7%, or at least 7.5% acrylic composition. In addition, such embodiments may have no more than 10%, such as no more than 9.5%, no more than 9%, no more than 8.5%, no more than 8%, no more than 7.5%, no more than 7%, no more than 6.5%, no more than 6%, no more than 5.5%, or no more than 5% acrylic composition. Some embodiments have 5.0% to 8.2% acrylic composition.

[0084] polyester resin

[0085] An exemplary binder is a polyester resin, such as that produced according to Example 5 of U.S. Patent No. 10,233,353. In an exemplary embodiment, the aqueous dispersion has a total polyester resin content of at least 0.5% by weight, such as at least 1% by weight, for example, at least 1.5% by weight, such as at least 2% by weight, for example, at least 2.2% by weight, such as at least 2.4% by weight, for example, at least 2.5% by weight, such as at least 2.6% by weight, for example, at least 2.7% by weight, such as at least 2.8% by weight, for example, at least 2.9% by weight, such as at least 3% by weight. In an exemplary embodiment, the aqueous dispersion has a total polyester resin content of at most 4% by weight, such as at most 3.5% by weight, for example, at most 3.0% by weight, such as at most 2.9% by weight, for example, at most 2.8% by weight, such as at most 2.7% by weight, for example, at most 2.6% by weight, such as at most 2.5% by weight, for example, at most 2% by weight, such as at most 1.5% by weight, for example, at most 1% by weight.

[0086] Certain embodiments herein have At least 0.5%, such as at least 1%, at least 1.5%, at least 2%, at least 2.5%, at least 3%, at least 3.5%, at least 4%, at least 4.5%, at least 5%, at least 5.5%, or at least 6% of the polyester component. In addition, such embodiments may have no more than 10%, such as no more than 9.5%, no more than 9%, no more than 8.5%, no more than 8%, no more than 7.5%, no more than 7%, no more than 6.5%, no more than 6%, or no more than 5.5%, no more than 5%, no more than 4.5%, no more than 4%, no more than 3.5%, no more than 3%, no more than 2.5%, or no more than 2% of the polyester component. Some embodiments have from 1.0% to 6.2% of the polyester component. As shown in Comparative Examples 1 and 2, the compositions without polyester exhibited inferior resistivity properties.

[0087] polyurethane resin

[0088] An exemplary binder is a polyurethane resin, Such as Polyurethane resin produced according to Example 2a of U.S. Patent No. 9,688,877.

[0089] In exemplary embodiments, the aqueous dispersion has at least 0.5 wt %, such as at least 1 wt %, for example at least 1.5 wt %, such as at least 2 wt %, for example at least 2.5 wt %, such as at least 3 wt %, for example at least 3.5 Heavy quantity%, such as at least 4 wt %, for example at least 4.5 wt %, such as at least 5 wt %, for example at least 5.5 wt %, such as at least 6 wt %, for example at least 6.1 wt %, such as at least 6.2 wt %, for example at least 6.3 wt %, such as at least 6.4 wt %, for example at least 6.5 wt %, such as at least 6.6 wt %, for example at least 6.7 wt %, such as at least 6.8 wt %, for example at least 6.9 wt %, such as at least 7 wt %. In an exemplary embodiment, the aqueous dispersion has a total polyurethane resin content of at most 10 wt %, such as at most 9 wt %, for example at most 8 wt %, such as at most 7.5 wt %, for example at most 7 wt %, such as at most 6.9 wt %, for example at most 6.8 wt %, such as at most 6.7 wt %, for example at most 6.6 wt %, such as at most 6.5 wt %, for example at most 6 wt %.

[0090] Certain embodiments herein do not include polyurethane. In embodiments that include polyurethane, these embodiments can have at least 0.1%, such as at least 0.5%, at least 1%, at least 1.5%, at least 2%, at least 2.5%, at least 3%, or at least 3.5% of the polyurethane component. In addition, these embodiments can have no more than 5%, such as no more than 4.5%, no more than 4%, no more than 3.5%, no more than 3%, no more than 2.5%, no more than 2%, no more than 1.5%, no more than 1%, or no more than 0.5%, or no more than 0.1% of the polyurethane component.

[0091] Mixed resin

[0092] An exemplary binder is a polyurethane polyester / (meth)acrylic acid-based copolymer hybrid resin ("hybrid resin") produced according to U.S. patent application No. 17 / 446,059, filed on August 26, 2021 (incorporated herein in its entirety). In an exemplary embodiment, the aqueous dispersion has a total hybrid resin content of at least 1% by weight, for example, at least 5% by weight, such as at least 10% by weight, for example, at least 20% by weight, such as at least 30% by weight, for example, at least 40% by weight, such as at least 50% by weight, for example, at least 60% by weight, such as at least 70% by weight, or for example, at least 75% by weight. In an exemplary embodiment, the aqueous dispersion has a total hybrid resin content of at most 80% by weight, such as at most 75% by weight, for example, at most 65% by weight, such as at most 55% by weight, for example, at most 45% by weight, such as at most 35% by weight, for example, at most 25% by weight, such as at most 20% by weight, for example, at most 15% by weight, such as at most 10% by weight, for example, at most 5% by weight. In certain embodiments, the aqueous dispersion has a total hybrid resin content of 10 to 50%.

[0093] crosslinking agent

[0094] The aqueous dispersions contemplated herein may contain one or more conventional crosslinking agents in a proportion corresponding to a solids contribution of 0 to about 40% by weight of the resin solids of the aqueous dispersion. Examples of such crosslinking agents include aminoplast resins, transesterification crosslinking agents, and crosslinking agents with free or reversibly blocked isocyanate groups. Examples of aminoplast resins include benzoguanamine resins, particularly melamine resins. Examples of transesterification crosslinking agents include trialkoxycarbonylaminotriazines. Examples of crosslinking agents with free or reversibly blocked isocyanate groups include conventional free or blocked polyisocyanate crosslinking agents known as crosslinking agents for coating compositions.

[0095] Melamine resin

[0096] An exemplary crosslinking agent is a melamine-formaldehyde resin. In an exemplary embodiment, the aqueous dispersion has a total melamine-formaldehyde resin content of at least 0.5 wt %, such as at least 1 wt %, for example at least 1.5 wt %, such as at least 2 wt %, for example at least 2.2 wt %, such as at least 2.4 wt %, for example at least 2.5 wt %, such as at least 2.6 wt %, for example at least 2.7 wt %, such as at least 2.8 wt %, for example at least 2.9 wt %, such as at least 3 wt %, for example at least 3.1 wt %, such as at least 3.2 wt %, for example at least 3.3 wt %, such as at least 3.4 wt %, for example at least 3.5 wt %, such as at least 3.6 wt %, for example at least 3.7 wt %, such as at least 3.8 wt %, for example at least 3.9 wt %, such as at least 4 wt %. In an exemplary embodiment, the aqueous dispersion has a total melamine-formaldehyde resin content of at most 6 wt%, such as at most 5 wt%, for example at most 4.5 wt%, such as at most 4.2 wt%, for example at most 4 wt%, such as at most 3.9 wt%, for example at most 3.8 wt%, such as at most 3.7 wt%, for example at most 3.6 wt%, such as at most 3.5 wt%, for example at most 3.4 wt%, such as at most 3.3 wt%, for example at most 3.2 wt%, such as at most 3.1 wt%, for example at most 3.0 wt%, such as at most 2.9 wt%, for example at most 2.8 wt%.

[0097] Certain embodiments herein have at least 0.5%, such as at least 1%, at least 1.5%, at least 2%, at least 2.5%, at least 3%, at least 3.5%, at least 4%, at least 4.5%, at least 5%, at least 5.5%, or at least 6% melamine component. In addition, these embodiments may have no more than 10%, such as no more than 9.5%, no more than 9%, no more than 8.5%, no more than 8%, no more than 7.5%, no more than 7%, no more than 6.5%, no more than 6%, or no more than 5.5%, no more than 5%, no more than 4.5%, no more than 4%, no more than 3.5%, no more than 3%, no more than 2.5%, or no more than 2% melamine component. Some embodiments have 2.5% to 2.8% melamine component.

[0098] additive

[0099] In an exemplary embodiment, the aqueous dispersion comprises additives such as neutralizing agents, fillers, and defoamers, as well as other desired and suitable additives. Examples are wetting agents, adhesion promoters, catalysts, leveling agents, anti-cratering agents, rheology control agents (e.g., thickeners), and light stabilizers (e.g., UV absorbers and / or HALS-based compounds (HALS, hindered amine light stabilizers)).

[0100] Exemplary neutralizing agents can be selected from amines and / or amino alcohols, but any suitable neutralizing agent can be used. In an exemplary embodiment, the aqueous dispersion has a total neutralizing agent content of at least 0.01% by weight, such as at least 0.05% by weight, for example, at least 0.08% by weight, such as at least 0.1% by weight, for example, at least 0.11% by weight, such as at least 0.12% by weight, for example, at least 0.13% by weight, such as at least 0.14% by weight, for example, at least 0.15% by weight. In an exemplary embodiment, the aqueous dispersion has a total neutralizing agent content of at most 0.5% by weight, such as at most 0.4% by weight, for example, at most 0.3% by weight, such as at most 0.25% by weight, for example, at most 0.2% by weight, such as at most 0.18% by weight, for example, at most 0.15% by weight, such as at most 0.13% by weight, for example, at most 0.1% by weight.

[0101] An exemplary filler is magnesium silicate, but any suitable filler may be used. Examples include barium sulfate, kaolin, talc, silicon dioxide, and layered silicates. In an exemplary embodiment, the aqueous dispersion has a total filler content of at least 3 wt%, such as at least 4 wt%, for example at least 5 wt%, such as at least 6 wt%, for example at least 7 wt%, such as at least 8 wt%, for example at least 9 wt%, such as at least 10 wt%. In an exemplary embodiment, the aqueous dispersion has a filler content of at most 12 wt%, such as at most 11 wt%, for example at most 10 wt%, such as at most 9 wt%, for example at most 8 wt%, such as at most 7 wt%, for example at most 6 wt%, such as at most 5 wt%.

[0102] In an exemplary embodiment, the aqueous dispersion has a total defoamer content of at least 0.1 wt %, such as at least 0.2 wt %, for example at least 0.25 wt %, such as at least 0.3 wt %, for example at least 0.33 wt %, such as at least 0.34 wt %, for example at least 0.35 wt %. In an exemplary embodiment, the aqueous dispersion has a defoamer content of at most 0.5 wt %, such as at most 0.4 wt %, for example at most 0.35 wt %, such as at most 0.34 wt %, for example at most 0.33 wt %, such as at most 0.3 wt %.

[0103] pigment

[0104] The aqueous dispersion may contain one or more conventional pigments or special effect pigments, including pigments selected from white, colored and black pigments. Examples of white, colored and black pigments are conventional inorganic or organic pigments known to those skilled in the art, such as titanium dioxide, iron oxide pigments, carbon black, azo pigments, phthalocyanine pigments, quinacridone pigments, pyrrolopyrrole pigments and perylene pigments. Examples of special effect pigments are conventional pigments that impart angular chromaticity and / or angular chromaticity of the color and / or brightness of the coating depending on the viewing angle, such as non-leafing metallic pigments of, for example, aluminum, copper or other metals; interference pigments, such as metallic pigments coated with metal oxides, such as aluminum coated with iron oxide, coated mica, such as mica coated with titanium dioxide, pigments imparting a graphite effect, flaky iron oxide, liquid crystal pigments, coated aluminum oxide pigments, coated silicon dioxide pigments.

[0105] The aqueous dispersion can be applied to a substrate, particularly an automotive substrate such as an automotive body, automotive body component, or other automotive part, to form a coating or film thereon. The automotive substrate can be a plastic or metal substrate, or a so-called hybrid substrate comprising plastic and metal. As previously mentioned, the automotive substrate can be an automotive body or an automotive body component; the automotive body can be a metal substrate or a hybrid substrate, while the automotive body component can be a metal substrate, a plastic substrate, or a hybrid substrate. The automotive plastic substrate can be uncoated or can have a pre-coating layer.

[0106] In an exemplary embodiment, the aqueous dispersion is sprayed onto a substrate to form a layer or film thereon. Spraying can be performed by any conventional spraying method; in the case of OEM coatings, a typical spraying method is electrostatically assisted high-speed rotary atomization, and this method can be performed to spray the aqueous dispersion in one or more spray passes, each spray pass being performed by electrostatically assisted high-speed rotary atomization. The film thickness of the total layer, which may be composed of two or more coating layers or sub-layers, is, for example, between about 7 and about 40 μm. The film thickness indicated herein for the coatings in each case refers to the dry film thickness.

[0107] Application of the aqueous dispersion may be followed by a drying procedure, particularly a brief, for example, about 30 seconds to about 30 minutes, flash phase at an air temperature of about 20 to about 100° C., after which an overcoat composition may be sprayed to form an overcoat layer.

[0108] Although at least one exemplary embodiment has been provided in the foregoing specific embodiments, it should be understood that there are a large number of variations. It should also be understood that the at least one exemplary embodiment described is merely an example and is not intended to limit the scope, applicability, or configuration in any way. On the contrary, the foregoing specific embodiments will provide a convenient roadmap for those skilled in the art to implement the exemplary embodiments. It should be understood that various changes may be made to the functions and arrangements of the elements described in the exemplary embodiments without departing from the scope specified in the appended claims.

Claims

1. A method for producing a conductive aqueous dispersion, the method comprising: mixing water, solvent, and binder to form a homogeneous mixture; and The carbon nanotubes are added to the homogeneous mixture and mixed under high shear to form a dispersion.

2. The method of claim 1, wherein the carbon nanotubes are electrically conductive, and wherein the dispersion comprises from about 5 to about 20% electrically conductive material based on total binder solids.

3. The method of claim 1, wherein the carbon nanotubes are electrically conductive, and wherein the dispersion comprises from about 10 to about 15% electrically conductive material based on total binder solids.

4. The method of claim 1, wherein the dispersion formed has a carbon nanotube content of about 0.5 to about 2.5 weight percent based on the total weight of the dispersion.

5. The method of claim 1, wherein the dispersion formed has a carbon nanotube content of about 1.0 to about 1.8 weight percent based on the total weight of the dispersion.

6. The method of claim 1 , wherein the dispersion is formed by: grafting the first acrylic resin component and the polyester resin component to each other; and The second acrylic resin component and the polyurethane resin component are grafted to each other.

7. The method of claim 1 , wherein the dispersion formed has: a total acrylic resin content of about 5 to 8.2% by weight; from about 1 to about 6.2 weight percent total polyester resin content; Up to about 3.7% by weight total polyurethane resin content.

8. The method of claim 1, wherein the dispersion formed has a binder content of about 16 to about 33 weight percent based on the total weight of the dispersion.

9. The method according to claim 1, wherein the binder comprises: acrylic resin; Polyester resin; polyurethane resin; and Melamine formaldehyde resin.

10. The method of claim 1 , wherein the dispersion formed has, based on the total weight of the dispersion: an acrylic resin content of about 5 to 8.2% by weight; a polyester resin content of about 1 to about 6.2 weight percent; A polyurethane resin content of about 0.0 to 3.7 weight percent; and A melamine formaldehyde resin content of about 2.5 to about 2.8 weight percent.

11. The method of claim 1 , further comprising mixing the filler with the water, solvent, and binder to form a homogeneous mixture.

12. The method of claim 11, wherein the filler is magnesium silicate.

13. The method of claim 11, wherein the dispersion formed has a filler content of about 5 to about 10 weight percent based on the total weight of the dispersion.

14. The method of claim 1, further comprising mixing a defoaming agent with the water, the solvent, and the binder to form a homogeneous mixture.

15. The method of claim 14, wherein the dispersion formed has a defoamer content of about 0.2 to about 0.5 weight percent based on the total weight of the dispersion.

16. The method of claim 1, further comprising mixing a neutralizing agent with the water, solvent, and binder to form a homogeneous mixture.

17. The method of claim 16, wherein the neutralizing agent is an amine.

18. The method of claim 16, wherein the dispersion formed has a neutralizing agent content of about 0.05 to about 0.25 weight percent based on the total weight of the dispersion.

19. A conductive aqueous dispersion comprising: water; solvents; Binder; and Carbon nanotubes; wherein the carbon nanotubes are electrically conductive, and wherein the dispersion comprises from about 5 to about 20% electrically conductive material based on total binder solids.

20. The conductive aqueous dispersion of claim 19, wherein the dispersion has: a carbon nanotube content of from about 0.5 to about 2.5 weight percent, based on the total weight of the dispersion; a water content of about 50 to about 70 weight percent, based on the total weight of the dispersion; a solvent content of from about 4 to about 8 weight percent, based on the total weight of the dispersion; and A binder content of about 16 to about 33 weight percent, based on the total weight of the dispersion.

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