Coating composition for rotary atomizing electrostatic coating device, coated film, and vehicle

Abstract

Provided is a coating composition for a rotary atomizing electrostatic coating device, which can suppress the attachment of a coating to an object other than the coating and improve coating efficiency. The coating composition for a rotary atomizing electrostatic coating device is characterized in that the rotary atomizing electrostatic coating device does not use shaping air in the atomization of the coating composition, and the coating composition has a resistance value of 0.02 to 1.5 MΩ.

Description

Technical Field

[0001] This invention relates to a coating composition, coating film, and vehicle for a rotary atomizing electrostatic coating device. Background Technology

[0002] Conventional coating apparatuses are known to atomize (also known as atomize) paint by blowing shaping air onto the paint being dispensed from a bell cup. In such apparatuses, the atomized paint is lifted up due to the reflection of the accompanying airflow of the shaping air onto the workpiece, resulting in a decrease in coating efficiency.

[0003] In contrast, a rotary atomizing electrostatic coating apparatus that does not use forming air has been proposed (for example, see Patent Document 1). The coating apparatus of Patent Document 1 is configured to discharge a linear coating material from a groove in a rotating head and electrostatically atomize the linear coating material. Then, the electrostatically atomized coating material adheres to a grounded object (conductor) through electrostatic force and is coated.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent document 1: Japanese Patent Application Publication No. 2019-055345. Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, in Patent Document 1, only the diameter of the linear coating is considered, without considering the characteristics and composition of the coating itself.

[0009] Furthermore, based on the inventors' research, it is known that if only existing coatings used in coating apparatuses employing forming air are applied using the rotary atomizing electrostatic coating apparatus of Patent Document 1, a portion of the electrostatically atomized coating emitted from the rotating head will not adhere to the object being coated, but rather to the outer periphery of the rotating head, which is not the object being coated, resulting in a decrease in coating efficiency. In this case, there is also a possibility that the coating adhering to the outer periphery of the rotating head will scatter and adhere to the object being coated, thus damaging its appearance. Furthermore, if the coating adheres to an object other than the object being coated (also known as "uneven paint spreading"), it not only has the disadvantage of decreased coating efficiency, but also incurs unnecessary steps and costs such as maintaining the object other than the object being coated, removing the coating adhering to the object other than the object being coated, or cleaning or replacing the object other than the object being coated.

[0010] Therefore, the object of the present invention is to provide a coating composition for a rotary atomizing electrostatic coating apparatus, wherein the coating composition for the rotary atomizing electrostatic coating apparatus can suppress the adhesion of the coating to the object and improve the coating efficiency.

[0011] Another object of the present invention is to provide a coating film using the coating composition described above.

[0012] Another object of the present invention is to provide a vehicle having the coating as described above.

[0013] Methods for solving problems

[0014] The coating composition of the present invention is a coating composition for a rotary atomizing electrostatic coating apparatus, characterized in that the rotary atomizing electrostatic coating apparatus does not use forming air in the micronization of the coating composition, and the resistivity of the coating composition is 0.02 to 1.5 MΩ. This suppresses the adhesion of the coating to the object and improves coating efficiency.

[0015] In one embodiment of the coating composition of the present invention, the coating composition contains 0.5% by mass or more of one or more selected from the group consisting of methanol, ethanol, 1-propanol, diethyl ether and capped isocyanate, relative to the total mass of the coating composition.

[0016] In one embodiment of the coating composition of the present invention, the coating composition comprises a compound having a dielectric constant of 3.0 F / m or more, the compound being a capped isocyanate, and the mass percentage of the compound relative to the total mass of the coating composition is 0.5% by mass or more.

[0017] In one embodiment of the coating composition of the present invention, the terminated isocyanate is a terminated isocyanate of 1,6-hexamethylene diisocyanate.

[0018] In one embodiment of the coating composition of the present invention, the coating composition comprises a compound having a dielectric constant of 3.0 F / m or more, the compound being selected from one or more of the group consisting of methanol, ethanol, 1-propanol and diethyl ether, and the mass percentage of the compound relative to the total mass of the coating composition is 0.5% by mass or more.

[0019] In one embodiment of the coating composition of the present invention, the resistance value is 0.02 to 1.0 MΩ.

[0020] In one embodiment of the coating composition of the present invention, the coating composition is a coating composition for forming a coating film on the outer panel of a vehicle.

[0021] In one embodiment of the coating composition of the present invention, the coating composition is a coating composition for forming a mid-coat film on the outer panel of a vehicle.

[0022] The coating of the present invention is a coating using the above-described coating composition for a rotary atomizing electrostatic coating apparatus.

[0023] The vehicle of the present invention is a vehicle having the above-described coating.

[0024] The effects of the invention

[0025] According to the present invention, a coating composition for a rotary atomizing electrostatic coating apparatus can be provided, which can suppress the adhesion of coating to the object and improve coating efficiency. According to the present invention, a coating film using the coating composition described above can be provided. According to the present invention, a vehicle having the coating film described above can be provided. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described. These descriptions are for illustrative purposes only and do not limit the scope of the invention in any way.

[0027] In this invention, two or more implementation methods can be combined arbitrarily.

[0028] In this specification, unless otherwise stated, numerical ranges mean both the upper and lower limits of the range. For example, 0.02 to 1.5 MΩ means above 0.02 MΩ and below 1.5 MΩ.

[0029] In this invention, coatings and coating compositions can be used interchangeably.

[0030] (Coating composition for rotary atomizing electrostatic coating device)

[0031] The coating composition of the present invention is a coating composition for a rotary atomizing electrostatic coating device, characterized in that the rotary atomizing electrostatic coating device does not use forming air in the microparticle formation of the coating composition, and the resistivity of the coating composition is 0.02 to 1.5 MΩ.

[0032] Based on the inventors' research, it was discovered that in a rotary atomizing electrostatic coating apparatus that does not use forming air in the micronization of coating compositions, by setting the resistance value of the coating composition to 0.02 to 1.5 MΩ, the adhesion of the coating to the object can be suppressed and the coating efficiency can be improved.

[0033] The resistivity of the coating composition of the present invention is 0.02 to 1.5 MΩ. If the resistivity is less than 0.02 MΩ, the droplets of the coating composition cannot be sufficiently charged. If the resistivity is greater than 1.5 MΩ, the adhesion of the coating to the object cannot be suppressed.

[0034] In one embodiment, the resistivity of the coating composition of the present invention is 0.02 MΩ or more, 0.05 MΩ or more, 0.1 MΩ or more, 0.2 MΩ or more, 0.3 MΩ or more, 0.4 MΩ or more, 0.5 MΩ or more, 0.6 MΩ or more, 0.7 MΩ or more, 0.8 MΩ or more, 0.9 MΩ or more, 1.0 MΩ or more, 1.1 MΩ or more, 1.2 MΩ or more, 1.3 MΩ or more, or 1.4 MΩ or more.

[0035] In another embodiment, the resistivity of the coating composition of the present invention is 1.5 MΩ or less, 1.4 MΩ or less, 1.3 MΩ or less, 1.2 MΩ or less, 1.1 MΩ or less, 1.0 MΩ or less, 0.9 MΩ or less, 0.8 MΩ or less, 0.7 MΩ or less, 0.6 MΩ or less, 0.5 MΩ or less, 0.4 MΩ or less, 0.3 MΩ or less, 0.2 MΩ or less, 0.1 MΩ or less, or 0.05 MΩ or less.

[0036] In one embodiment of the coating composition of the present invention, the resistance value is 0.02 to 1.0 MΩ. Further research by the inventors has revealed that even in rotary atomizing electrostatic coating apparatuses, as described in paragraph

[0038] of Patent Document 1, where the voltage applied to the rotary head is controlled by a voltage generator to maintain a constant current flow between the rotary head and the workpiece (hereinafter, sometimes referred to as a "voltage-controlled constant current type apparatus"), if the resistance value of the coating composition is high, a high voltage is applied to the rotary atomizing electrostatic coating apparatus to maintain a constant current, sometimes causing the coating apparatus to stop abnormally. If the coating apparatus stops abnormally, unnecessary operations or material losses occur, such as confirming the cause of the stop, eliminating the cause of the stop, discarding or recoating defective coated products due to uneven coating caused by the stop, and restarting the coating apparatus, resulting in decreased productivity. In contrast, by setting the resistance of the coating composition to 0.02 to 1.0 MΩ, it is possible to prevent the application of high voltage to the coating equipment, suppress abnormal stops of the coating equipment, and ensure stable coating.

[0037] The method for controlling the resistivity of the coating composition of the present invention within the range of 0.02 to 1.5 MΩ is not particularly limited. For example, one or more of the following can be selected from the group consisting of methanol, ethanol, 1-propanol, diethyl ether, and capped isocyanates. Examples of capped isocyanates include, for example, capped isocyanates of 1,6-hexamethylene diisocyanate. Furthermore, commercially available capped isocyanates include, for example, "7961" manufactured by Baxenden; and "DURANATE SBB-70P" and "DURANATEMFK-60B" manufactured by Asahi Kasei Corporation.

[0038] The amount of one or more selected from the group consisting of methanol, ethanol, 1-propanol, diethyl ether, and capped isocyanate is, for example, 0.5% by mass or more relative to the total mass of the coating composition. In one embodiment, the amount of one or more selected from the group consisting of methanol, ethanol, 1-propanol, diethyl ether, and capped isocyanate is 0.5 to 10% by mass relative to the total mass of the coating composition.

[0039] In one embodiment of the coating composition of the present invention, the coating composition contains 0.5% by mass or more of one or more selected from the group consisting of methanol, ethanol, 1-propanol, diethyl ether and capped isocyanate, relative to the total mass of the coating composition.

[0040] Alternatively, as a method for controlling the resistivity of the coating composition of the present invention to be in the range of 0.02 to 1.5 MΩ, for example, a compound having a constant dielectric constant can be used.

[0041] In one embodiment of the coating composition of the present invention, the coating composition comprises a compound having a dielectric constant of 3.0 F / m or higher.

[0042] The compound is present in a mass percentage of 0.5% or more relative to the total mass of the coating composition. Therefore, the resistivity of the coating composition of the present invention can be easily controlled within the range of 0.02 to 1.5 MΩ.

[0043] Examples of compounds having a dielectric constant of 3.0 F / m or higher (hereinafter sometimes simply referred to as "specified compounds") include, for example, methanol (33.1 F / m), ethanol (23.8 F / m), 1-propanol (22.1 F / m), isobutanol (2-methylpropanol) (18.9 F / m), diacetone alcohol (18.2 F / m), n-butanol (17.1 F / m), 2-butanol (15.5 F / m), and benzyl alcohol (13.1 F / m), etc.

[0044] Other examples of compounds specified include diethyl ether (dielectric constant 4.2 F / m) and end-capped isocyanates.

[0045] In one embodiment of the coating composition of the present invention, the coating composition comprises a compound having a dielectric constant of 3.0 F / m or more, the compound being a capped isocyanate, and the mass percentage of the compound relative to the total mass of the coating composition is 0.5% by mass or more.

[0046] In one embodiment of the coating composition of the present invention, the terminated isocyanate is a terminated isocyanate of 1,6-hexamethylene diisocyanate.

[0047] In one embodiment of the coating composition of the present invention, the coating composition comprises a compound having a dielectric constant of 3.0 F / m or more, said compound being one or more selected from the group consisting of methanol, ethanol, 1-propanol and diethyl ether, and said compound being present in a mass ratio of 0.5% by mass or more relative to the total mass of said coating composition.

[0048] In the coating composition of the present invention, from the viewpoint of reducing volatile organic compounds (VOCs) derived from the coating composition, the compound is preferably a non-alcoholic solvent.

[0049] In one embodiment of the coating composition of the present invention, the compound is specified as a capped isocyanate.

[0050] The regulations stipulate that compounds can be used alone or in combination of two or more.

[0051] By setting the mass ratio of the specified compound relative to the total mass of the coating composition of the present invention to 0.5% by mass or more, the resistivity of the coating composition of the present invention can be easily controlled within the range of 0.02 to 1.5 MΩ. In one embodiment, the mass ratio of the specified compound relative to the total mass of the coating composition of the present invention is 0.5 to 10% by mass.

[0052] The coating composition of the present invention may also contain resin, crosslinking agent, pigment, solvent (solvent other than the specified compound), pigment dispersant, anti-sagging agent, viscosity modifier, anti-settling agent, reaction accelerator, crosslinking accelerator, curing agent, leveling agent, surface conditioner, defoamer, plasticizer, preservative, mildew inhibitor, and other components such as UV stabilizer. These components may also be used individually or in combination of two or more.

[0053] Resin components

[0054] As a resin component, resin components of conventionally known coating compositions can be used. Examples of resin components include, for instance, polyester resins, melamine resins, epoxy resins, acrylic resins, alkyd resins, fluororesins, polyurethane resins, polyether resins, and modified versions of these. Additionally, as a resin component, examples include silicone resins, alkoxysilane condensates, and other polymeric compounds containing inorganic components, or composed of inorganic components. One or more resin components can also be used alone or in combination.

[0055] There are no specific limitations on the content of resin components; they can be adjusted appropriately.

[0056] The resin component preferably has curable functional groups that react with a crosslinking agent. These functional groups can be any type, including, for example, hydroxyl, carboxyl, and epoxy groups. As the curable functional group of the resin component used in the coating composition of the present invention, hydroxyl groups are preferred because they can react with end-capped isocyanate compounds having a specific range of dielectric constants.

[0057] Crosslinking agent

[0058] Crosslinking agents can be selected based on the curable functional groups possessed by the resin components. Examples of crosslinking agents include carbodiimide compounds, hydrazine compounds, amino resins, polyisocyanate compounds, end-capped polyisocyanate compounds, amine compounds, polyamide compounds, and polycarboxylic acid compounds. Crosslinking agents can also be used alone or in combination of two or more.

[0059] As the crosslinking agent used in the coating composition of the present invention, a terminal isocyanate compound having a specific range of dielectric constants is preferably used. It can also be used in combination with the terminal isocyanate compound described above and other crosslinking agents.

[0060] Isocyanate compounds (1) can be categorized as alicyclic compounds, aliphatic or aromatic compounds containing aromatic groups. As preferred examples of isocyanate compounds, diisocyanates or their isocyanurates (trimers of diisocyanates) can be mentioned.

[0061] As a diisocyanate, for example, a diisocyanate having 5 to 24 carbon atoms can be used, and a diisocyanate having 6 to 18 carbon atoms is preferred.

[0062] Examples include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexane diisocyanate, undecane-1,11-diisocyanate, lysine ester diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-isocyano-3-isocyano-methyl-3,5,5-trimethylcyclohexane (IPDI), 4,4'-diisocyanate dicyclomethane, ω,ω'-dipropyl ether diisocyanate, thiodipropyl diisocyanate, and cyclohexyl-1,4-diisocyanate. 4-Diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,5-dimethyl-2,4-bis(isocyanate methyl)benzene, 1,5-trimethyl-2,4-bis(ω-isocyanate ethyl)benzene, 1,3,5-trimethyl-2,4-bis(isocyanate methyl)benzene, 1,3,5-triethyl-2,4-bis(isocyanate methyl)benzene, dicyclohexyldimethylmethane-4,4'-diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and diphenylmethane-4,4'-diisocyanate, etc.

[0063] In addition, aromatic diisocyanates such as 2,4-diisocyanate-toluene, 2,6-diisocyanate-toluene, 4,4'-diisocyanate-diphenylmethane, 1,4-diisocyanate-isopropylbenzene, cyclohexyl-1,4-diisocyanate, toluene diisocyanate, and hexamethylene diisocyanate can also be used. Furthermore, mixtures of these compounds can also be used.

[0064] As isocyanurates, the trimer of the aforementioned diisocyanate can be cited as an example. In addition, isocyanates or mixtures of diisocyanates or diisocyanate trimers can also be used.

[0065] melamine resin

[0066] The melamine resin is not particularly limited; it can be the same resin as the melamine resin (ii) contained in the above-mentioned intermediate coating composition, or it can be a different resin. For example, methylated melamine resin, butylated melamine resin, or methyl / butyl mixed melamine resin can be used. Examples include "Cymel-303" and "Cymel254" manufactured by Nihon Cytec Industries Inc., "U-Van 20N60" and "U-Van 128" manufactured by Mitsui Chemicals, and the "Sumimal" series manufactured by Sumitomo Chemical Company, Limited.

[0067] Compared to the solid components of coating-forming resins such as urea-modified acrylic resin, polyurethane-modified polyester resin, and melamine resin, the amount of melamine resin used is preferably set to 10-40% by mass, more preferably 15-35% by mass. Curing properties are improved when the amount of melamine resin used is 10% by mass or more. Furthermore, the chipping resistance is better when the amount of melamine resin used is 40% by mass or less after coating.

[0068] pigment

[0069] As a pigment, there are no particular limitations, and well-known paint pigments can be used. Examples of pigments include: coloring pigments such as titanium dioxide, carbon black, iron oxide red, and phthalocyanine blue; extender pigments such as precipitating barium sulfate, calcium carbonate, talc, mica, and kaolin; rust-preventive pigments; and infrared-reflecting pigments. Pigments can also be used alone or in combination of two or more.

[0070] Glossy pigments

[0071] The shape is not particularly limited as a glossy pigment. Glossy pigments can also be colored. For example, flaky pigments with an average particle size (D50) of 2 to 50 μm and a thickness of 0.1 to 5 μm are preferred as glossy pigments. In addition, pigments with an average particle size in the range of 10 to 35 μm have excellent gloss and are more preferably used.

[0072] The pigment concentration (PWC) of the glossy pigment in the coating composition is, for example, 1 to 23.0%. If the PWC of the glossy pigment is below 23%, the coating film appearance is more easily improved. The PWC of the glossy pigment is preferably 1.5% to 20.0%, more preferably 2.0% to 18.0%. It should be noted that pigment concentration (PWC) represents the pigment content (%) based on the mass of the resin solids component.

[0073] Examples of glossy pigments include uncolored or colored metallic glossy materials such as metals or alloys, mixtures thereof, interference mica powder, colored mica powder, muscovite powder, graphite, or colorless or colored flat pigments. Because they can form coatings with excellent dispersibility and high transparency, uncolored or colored metallic glossy materials such as metals or alloys, mixtures thereof, interference mica powder, colored mica powder, and muscovite powder are preferred. Specific examples of metals include aluminum, alumina, copper, zinc, iron, nickel, and tin.

[0074] Furthermore, it can contain coloring pigments as needed. Examples of coloring pigments include those listed in the description of intermediate coating compositions or inorganic pigments. Even further, calcium carbonate, barium sulfate, clay, and talc can be used in combination as extender pigments.

[0075] The total pigment concentration (PWC) in the metallic coating composition, which includes glossy pigments and all other pigments, is 1 to 50%, preferably 1.5% to 40%, and more preferably 2.0% to 30%. If the total pigment concentration (PWC) is 50% or less, the coating appearance is more likely to be good.

[0076] solvent

[0077] As a solvent, solvents of conventionally known coating compositions can be appropriately selected for use. Examples include: alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, diacetone alcohol, and benzyl alcohol; esters such as ethyl acetate, butyl acetate, isobutyl acetate, ethyl propionate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; ethers such as diethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, dioxane, and tetrahydrofuran (THF); and ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, etc. Diols such as 1,3-butanediol, pentanediol, and 1,3-octanediol; amides such as formamide, N-methylformamide, dimethylformamide (DMF), dimethylacetamide, dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP); ketones such as acetone, methyl ethyl ketone (MEK), methyl propyl ketone, methyl isobutyl ketone, acetylacetone, and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, mesitylene, and dodecylbenzene; and halogen solvents such as chloroform and dichloromethane.

[0078] In one embodiment, the coating composition of the present invention is a solvent-based coating.

[0079] use

[0080] The coating composition of the present invention can be any substance used in a rotary atomizing electrostatic coating device and can be used in known coating applications. Examples of applications for the coating composition of the present invention include: intermediate coats, base coats, and clear coats for the exterior panels of vehicles such as automobiles, motorcycles, trams, buses, trucks, and taxis; intermediate coats, base coats, and clear coats for vehicle parts; aircraft such as airplanes and helicopters; household appliances such as refrigerators, washing machines, and televisions; computer equipment such as personal computers and smartphones; building materials such as steel doors, steel window frames, steel blinds, storage rooms, fences, steps, railings, and door handles; gas water heaters such as instrument boxes, exhaust fans, and water heaters; steel furniture such as storage cabinets, filing cabinets, partitions, and shelves; cast iron pipes such as valves; and intermediate coats, base coats, and clear coats for the exterior panels of castings such as conveyors, chain blocks, and manhole covers.

[0081] In one embodiment of the coating composition of the present invention, the coating composition is a coating composition for forming a coating film on the outer panel of a vehicle.

[0082] In one embodiment of the coating composition of the present invention, the coating composition is a coating composition for forming a mid-coat film on the outer panel of a vehicle.

[0083] The substrate to be coated with the coating composition is not particularly limited as long as it is a material that can be coated using a rotary atomizing electrostatic coating device; it can be appropriately selected. Examples of substrates include metals such as steel plates, iron, aluminum, and copper; and materials such as glass, plastics, and wood with a metal film or conductive film formed on their surface. The substrate can also undergo galvanizing, chemical forming, and electrodeposition treatments.

[0084] The rotary atomizing electrostatic coating apparatus using the coating composition of the present invention can also be a known rotary atomizing electrostatic coating apparatus, for example, the coating apparatus of Patent Document 1. Furthermore, the rotary atomizing electrostatic coating apparatus can be either a voltage-controlled constant current type or a current-controlled constant voltage type (a rotary atomizing electrostatic coating apparatus that controls the current applied to the rotary head to keep the voltage flowing between the rotary head and the workpiece constant).

[0085] In one embodiment, the rotary atomizing electrostatic coating apparatus of the present invention, which uses a coating composition for a rotary atomizing electrostatic coating apparatus, is a voltage-controlled constant current type apparatus.

[0086] Method for preparing coating compositions

[0087] The method for preparing the coating composition is not particularly limited except that the resistivity of the coating composition is set to 0.02 to 1.5 MΩ. The components can be mixed and prepared according to conventionally known methods.

[0088] (Coating)

[0089] The coating of the present invention is a coating using the coating composition for the above-mentioned rotary atomizing electrostatic coating apparatus.

[0090] There is no particular limitation on the film thickness after drying; it can be adjusted appropriately. For example, the film thickness after drying is 5–50 μm. In one embodiment, the film thickness after drying is 25–40 μm. In another embodiment, the film thickness after drying is 30–35 μm.

[0091] In one embodiment, the coating of the present invention is a mid-coat coating for the outer panel of a vehicle.

[0092] In another embodiment, the coating of the present invention is a topcoat base coating for the outer panel of a vehicle.

[0093] In another embodiment, the coating of the present invention is a transparent coating applied to the outer panel of a vehicle.

[0094] In another embodiment, the coating of the present invention is a mid-coat coating for an automotive exterior panel.

[0095] In another embodiment, the coating of the present invention is a topcoat base coating for an automotive exterior panel.

[0096] In another embodiment, the coating of the present invention is a transparent coating for the outer panel of an automobile.

[0097] Coating preparation method

[0098] The method for preparing the coating film is not particularly limited except for using the coating composition of the rotary atomizing electrostatic coating apparatus of the present invention and applying the coating using the rotary atomizing electrostatic coating apparatus. For example, conventionally known coating methods such as forming multiple layers of coating film and baking can be used.

[0099] The drying temperature after coating with the paint composition using the rotary atomizing electrostatic coating apparatus of the present invention can be appropriately adjusted according to the solvent and coating environment. For example, it can be 140-150°C in the case of a drying time of 20-30 minutes.

[0100] There are no particular limitations on the articles having the coating of this invention. Examples include vehicles such as automobiles, motorcycles, trams, buses, trucks, and taxis; vehicle parts; aircraft such as airplanes and helicopters; household appliances such as refrigerators, washing machines, and televisions; computer equipment such as personal computers and smartphones; building materials such as steel doors, steel window frames, steel blinds, storage rooms, fences, steps, railings, and door handles; gas water heaters such as instrument boxes, exhaust fans, and water heaters; steel furniture such as storage cabinets, filing cabinets, partitions, and shelves; cast iron pipes such as valves; and castings such as conveyors, chain pulleys, and manhole covers.

[0101] The articles of the present invention may have only one or more coatings of the present invention. In addition to one or more coatings of the present invention, the articles may also have one or more coatings using known paint compositions.

[0102] (vehicle)

[0103] The vehicle of the present invention is a vehicle having the above-described coating. There are no particular limitations on the vehicle, and any known vehicle can be appropriately selected. Examples of vehicles include automobiles; motorcycles; trams; buses; trucks; taxis; and special vehicles such as vehicle-mounted cranes, trailers, garbage trucks, and armored vehicles.

[0104] The vehicle of the present invention may have only one or more coatings of the present invention. The article may have a coating, in addition to one or more coatings of the present invention, or a coating using one or more known paint compositions.

[0105] Example

[0106] The present invention will be described in more detail below with reference to embodiments, but these embodiments are for illustrative purposes only and do not limit the present invention in any way.

[0107] The materials used in the examples are as follows.

[0108] Compound 1 is specified as a capped isocyanate manufactured by Baxenden under the trade name "7961", which is described as "7961" in Table 1.

[0109] Compound 2 is specified as a capped isocyanate, manufactured by Asahi Kasei Corporation, trade name "DURANATEMFK-60B", and described as "MFK-60B" in Table 1.

[0110] Compound 3 is specified as ethanol.

[0111] Compound 4 is specified as diethyl ether.

[0112] Manufacturing Example 1: Manufacturing of Polyurethane Modified Polyester Resin for Intermediate Coating Compositions

[0113] In a 2L reaction vessel equipped with a nitrogen inlet tube, stirrer, temperature controller, dropping funnel, and cooling pipe with a water separator, 440 parts by weight of isophthalic acid, 20 parts by weight of hexahydrophthalic acid, 40 parts by weight of azelaic acid, 300 parts by weight of trimethylolpropane, and 200 parts by weight of neopentyl glycol were added. After dissolving the raw materials by heating and stirring, 0.2 parts by weight of dibutyltin oxide were added, and stirring was initiated. The reaction layer temperature was slowly increased from 180°C to 220°C over 3 hours. The generated condensation water was distilled off and removed from the system. After reaching 220°C, the temperature was maintained for one hour, and 20 parts by weight of xylene were slowly added to the reaction layer, and the condensation reaction was carried out in the presence of the solvent. After the resin acid value reached 10 mg KOH / g, the temperature was cooled to 100°C, and 100 parts by weight of hexamethylene diisocyanate were slowly added over 30 minutes. Further, after maintaining for one hour, 200 parts by mass of xylene and 200 parts by mass of butyl acetate were added to obtain a polyurethane-modified polyester resin. The polyurethane-modified polyester resin has a solid content of 70%, a number average molecular weight of 2000, an acid value of 8 mg KOH / g (based on solid content), a hydroxyl value of 120 (based on solid content), and a glass transition temperature (Tg) of 60°C.

[0114] Manufacturing Example 2: Manufacturing of Non-Aqueous Dispersions for Intermediate Coating Compositions

[0115] (a) Manufacturing of dispersion stabilizing resin

[0116] 90 parts by mass of butyl acetate were added to a container equipped with a stirrer, temperature control device, and reflux cooler. Then, 20 parts by mass of a solution consisting of 38.9 parts by mass of methyl methacrylate, 38.8 parts by mass of stearate methacrylate, 22.3 parts by mass of 2-hydroxyethyl acrylate, and 5.0 parts by mass of azobisisobutyronitrile (AIBN) was added, and the mixture was heated while stirring to raise the temperature. At 110°C, the remaining 85 parts by mass of the above mixed solution were added dropwise over 3 hours, followed by the addition of a solution consisting of 0.5 parts by mass of AIBN and 10 parts by mass of butyl acetate over 30 minutes. The reaction solution was further stirred and refluxed for two hours to increase the rate of change to the resin, after which the reaction was terminated, yielding an acrylic resin with a solid content of 50% and a number average molecular weight of 5600.

[0117] (b) Manufacturing of non-aqueous dispersions

[0118] 90 parts by weight of butyl acetate and 120 parts by weight (60 parts by weight of solids) of acrylic resin obtained in the manufacture of the dispersion-stabilized resin described in (a) above were added to a container equipped with a stirrer, cooler, and temperature control device. Then, a solution consisting of 7.0 parts by weight of styrene, 1.8 parts by weight of methacrylic acid, 12.0 parts by weight of methyl methacrylate, 8.5 parts by weight of ethyl acrylate, 40.7 parts by weight of 2-hydroxyethyl acrylate, and 1.4 parts by weight of azobisisobutyronitrile was added dropwise over 3 hours at 100°C. Then, a solution consisting of 0.1 parts by weight of azobisisobutyronitrile and 1 part by weight of butyl acetate was added dropwise over 30 minutes. After further stirring of the reaction solution for one hour, an emulsion with a solids content of 60% and a particle size of 180 nm was obtained. The emulsion was diluted with butyl acetate to obtain a core-shell butyl acetate dispersion with a non-aqueous dispersion content of 40% by mass and a viscosity of 300 cps (25°C). The particle size of the non-aqueous dispersion was 180 nm. The Tg of the non-aqueous dispersion resin was 23°C and the hydroxyl value was 162 (based on solids content).

[0119] Manufacturing Example 3: Manufacturing of Intermediate Coating Composition 1

[0120] To a 1L container, add 107 parts by weight of polyurethane-modified polyester resin varnish for the intermediate coating composition obtained in the previous manufacturing example, 280 parts by weight of CR-97 (titanium oxide manufactured by Ishihara Sangyo Co., Ltd.), 13 parts by weight of MA-100 (carbon black pigment manufactured by Mitsubishi Chemical Group), 7 parts by weight of LMS-100 (flaky talc manufactured by Fuji Talc Co., Ltd.), 47 parts by weight of butyl acetate, and 47 parts by weight of xylene. Add an equal amount of GB503M (1.6mm glass beads) and disperse using a benchtop sand mill at room temperature for 3 hours to obtain a gray pigment paste. The particle size at the end of dispersion is 5μm or less, measured using a fineness meter. The pigment paste was obtained by filtering the glass beads.

[0121] The above-mentioned pigment paste contains 130 parts by weight of polyurethane-modified polyester resin for intermediate coating composition, 53 parts by weight of non-aqueous dispersion for intermediate coating composition, 71 parts by weight of U-Van128 (melamine resin manufactured by Mitsui Chemicals, Inc., 60% by solids), 0.5 parts by weight of capped isocyanate "7961" (manufactured by Baxenden), and capped isocyanate "DURANATE MFK-60B" (manufactured by Asahi Kasei, 60% by solids). 6.7 parts by weight (%)

[0122] Furthermore, a 1:1 mixture of ethyl ethoxypropionate and S-100 (an aromatic hydrocarbon solvent manufactured by Exxon Corporation) was diluted and adjusted for 19 seconds at 20°C using a Ford cup (No. 4) to prepare the intermediate coating composition 1. The non-volatile content during coating was 49%.

[0123] (Manufacturing Examples 4-11: Manufacturing of intermediate coating compositions 2-9)

[0124] Except for changes to the proportions of the two end-capped isocyanates and the proportions of ethanol or diethyl ether in intermediate coating composition 1 as shown in Table 1, intermediate coating compositions 2 to 9 were formulated in the same manner as in manufacturing example 3.

[0125] (Manufacturing Example 12: Manufacturing of Comparative Intermediate Coating Composition)

[0126] Except for changing the proportions of the two end-capped isocyanates in intermediate coating composition 1 as shown in Table 1, a comparative intermediate coating composition was prepared in the same manner as in manufacturing example 3.

[0127] (Manufacturing Example 13: Manufacturing of polyurethane-modified polyester resin for base coating composition)

[0128] 334 parts by mass of isophthalic acid, 311 parts by mass of hexahydrophthalic acid, 57 parts by mass of ethylene glycol, 105 parts by mass of trimethylolpropane, and 289 parts by mass of neopentyl glycol were added to a 2L reaction vessel equipped with a nitrogen inlet tube, stirrer, temperature controller, dropping funnel, and cooling pipe with a water separator. After the raw materials were dissolved and stirred by heating, 0.2 parts by mass of dibutyltin oxide were added, and stirring was started. The reaction layer temperature was slowly increased from 180℃ to 220℃ over 3 hours. The generated condensation water was distilled off the system. After reaching 220℃, the temperature was maintained for one hour, and 20 parts by mass of xylene were slowly added to the reaction layer. The condensation reaction was carried out in the presence of the solvent. After the resin acid value reached 8 mg KOH / g, the temperature was cooled to 100℃, and 10 parts by mass of hexamethylene diisocyanate were slowly added over 30 minutes. Further, after maintaining the mixture for one hour, 344 parts by mass of xylene, 43 parts by mass of butyl acetate, and 43 parts by mass of n-butanol were added to obtain a polyurethane-modified polyester resin. The polyurethane-modified polyester resin had a solid content of 70%, a number average molecular weight of 1800, a weight average molecular weight of 10000, an acid value of 6 mg KOH / g (based on solid content), and a hydroxyl value of 100 (based on solid content).

[0129] (Manufacturing Example 14: Manufacturing of Acrylic Resin for Base Coating Composition)

[0130] 50 parts by mass of xylene and 14 parts by mass of n-butanol were added to a 1L reaction vessel equipped with a nitrogen inlet tube, stirrer, temperature controller, dropping funnel, and cooling tube with a water separator. The temperature was set to 110°C. Then, a mixed solution containing 5 parts by mass of styrene, 35.3 parts by mass of ethyl acrylate, 41.1 parts by mass of butyl methacrylate, 15.5 parts by mass of hydroxyethyl acrylate, 3.1 parts by mass of methacrylic acid, and 4.0 parts by mass of tert-butyl peroxy-2-ethylhexanoate was added dropwise over 3 hours. Then, a solution consisting of 1.0 part by mass of tert-butyl peroxy-2-ethylhexanoate and 6 parts by mass of xylene was added dropwise over 30 minutes, and the mixture was maintained at 110°C for one hour. An acrylic resin was obtained with a solids content of 60%, an acid value of 20 mg KOH / g (based on solids content), a hydroxyl value of 75 (based on solids content), and a number average molecular weight of 5000.

[0131] (Manufacturing Example 15: Manufacturing of Solvent-Based Metal Substrate Coating Composition)

[0132] In a stainless steel container, 75 parts by weight of AS-9606 (urea-modified acrylic resin manufactured by Mitsubishi Rayon Co., Ltd., with a urea modification amount of 6.5%, an acid value of 12 mg KOH / g (based on solids), a hydroxyl value of 70 (based on solids), a weight-average molecular weight of 7000, and a Tg of 16°C), 14.3 parts by weight of the polyurethane-modified polyester for the base coating composition in Manufacturing Example 13, and 33.9 parts by weight of a pigment dispersion paste obtained by pre-dispersing 2.9 parts by weight of Cyanine Blue G-314 (blue pigment manufactured by Sanyo Pigment Co., Ltd.) and 6.0 parts by weight of Barifine BF-40 (barium sulfate pigment manufactured by Sakai Chemical Co., Ltd.) to 25 parts by weight of the acrylic resin for the base coating composition in Manufacturing Example 14 so that their respective particle sizes are less than 5 μm, and U-Van A light blue solvent-based metallic base coating composition (PWC 17.0%) was prepared by mixing 50 parts by weight of 20N60 (butylated melamine resin manufactured by Mitsui Chemicals Co., Ltd., 60% by solids) and 11.6 parts by weight of aluminum paste 7640NS (aluminum pigment manufactured by Toyo Aluminum Co., Ltd.) using a benchtop mixer.

[0133] Then, the above solvent-based metal substrate coating composition was diluted with a diluent consisting of 10 parts by weight of Solvesso 150 (a hydrocarbon solvent manufactured by Exxon Oil Corporation), 40 parts by weight of ethyl acetate, 40 parts by weight of toluene, and 10 parts by weight of butyl acetate using a No. 4 Ford cup at 20°C for 12.5 seconds to obtain substrate coating composition 1.

[0134] (Manufacturing Example 16: Synthesis of Acrylic Resin Containing Anhydride Groups (Component (a)))

[0135] 46.5 parts by mass of propylene glycol monomethyl ether acetate and 51.8 parts by mass of Solvesso 100 (an aromatic hydrocarbon solvent manufactured by Esso) were added to a reaction vessel equipped with a thermometer, stirrer, cooling pipe, nitrogen inlet pipe, and dropping funnel, and the temperature was raised to 130°C. In the same container, using a dropping funnel, a solution consisting of 16.4 parts by mass of styrene monomer, 18.86 parts by mass of n-butyl acrylate, 7.7 parts by mass of isobornyl acrylate, 22.53 parts by mass of cyclohexyl methacrylate, 13.94 parts by mass of 2-ethylethyl acrylate, 18 parts by mass of maleic anhydride, 2.57 parts by mass of acrylic acid, 8.5 parts by mass of tert-butyl peroxy-2-ethylhexanoate, and 5.2 parts by mass of Solvesso 100 was added dropwise over 3 hours. After the addition was complete, the temperature was maintained at 130°C for 30 minutes. Then, over another 30 minutes, a solution consisting of 1 part by mass of tert-butyl peroxy-2-ethylhexanoate and 2.2 parts by mass of Solvesso 100 was added dropwise. After this addition was completed, the reaction was further continued at 130°C for one hour to obtain a varnish with 58% non-volatile components. The varnish contained an anhydride-containing acrylic resin with a number average molecular weight of 3100 and an anhydride group concentration of 1.84 mmol / g (based on solids).

[0136] (Manufacturing Example 17: Synthesis of a carboxyl-containing polyester resin (Component (b)))

[0137] Add 8.85 parts by mass of pentaerythritol, 57.5 parts by mass of Placcel M (ε-caprolactone monomer manufactured by Daicel, trade name), 33.92 parts by mass of Rikacid HH-A (hexahydrophthalic anhydride manufactured by New Japan Chemical Co., Ltd, trade name), and 0.1 parts by mass of dibutyltin oxide to a reaction vessel equipped with a thermometer, stirrer, cooling pipe, and nitrogen inlet pipe, and heat to 150°C. After maintaining the temperature at 150°C for two hours, 616 parts by mass of hexahydrophthalic anhydride dissolved by heating were added. After maintaining the temperature at 150°C for one hour, the mixture was cooled and diluted with 33.4 parts by mass of ethyl 3-ethoxypropionate to obtain a varnish with 75% non-volatile components. The varnish contains a carboxyl-containing polyester resin with a number average molecular weight of 2500, a weight average molecular weight / number average molecular weight ratio of 1.3, a carboxyl group content of 2.2 mmol / g (based on solids), and a hydroxyl group content of 0.32 mmol / g (based on solids).

[0138] (Manufacturing Example 18: Synthesis of acrylic resin containing hydroxyl and epoxy groups (Component (c)))

[0139] 23.7 parts by weight of ethyl 3-ethoxypropionate were added to an autoclave equipped with a thermometer, stirrer, cooling pipe, nitrogen inlet pipe, and dropping funnel, and the temperature was raised to 170°C. A solution consisting of 25 parts by weight of styrene, 30.3 parts by weight of glycidyl methacrylate, 8 parts by weight of n-butyl acrylate, 23.9 parts by weight of isobornyl acrylate, 12.8 parts by weight of 4-hydroxybutyl acrylate, and 3.0 parts by weight of di-tert-amyl peroxide and 2.6 parts by weight of ethyl 3-ethoxypropionate were added dropwise to the above reaction vessel over 3 hours using a pump.

[0140] After the addition was completed, the mixture was kept at 170°C for 30 minutes. Then, a solution consisting of 0.4 parts by mass of di-tert-butyl peroxide and 1.5 parts by mass of ethyl 3-ethoxypropionate was added dropwise over 30 minutes using a pump. After this addition was completed, the reaction was further continued at 170°C for one hour to obtain a varnish with a non-volatile content of 76%. The varnish contained an acrylic resin with a number average molecular weight of 2200, an epoxy group content of 2.1 mmol / g (based on solids), and a hydroxyl group content of 0.9 mmol / g (based on solids).

[0141] (Manufacturing Example 19: Formulation of Transparent Coating Composition 1)

[0142] In a stainless steel beaker, 32g of anhydride-containing acrylic resin (component (a)) and 15g of carboxyl-containing polyester resin (component (b)) were mixed as the first component.

[0143] On the other hand, a second component was prepared by mixing 53g of acrylic resin (component (c)) based on the resin solids content, 2 parts by weight of "TINUVIN 900" UV absorber manufactured by CHIBA SPECIALTY, 1 part by weight of "Sanol LS-440" light stabilizer manufactured by Sankyo Organics, and 0.1 parts by weight of "Modaflow" surface conditioner manufactured by UCB. If the two components are stored in a liquid state, they will not react at room temperature. The first and second components obtained above were mixed immediately before use, and the viscosity was adjusted for 28 seconds in a Ford cup using a 1 / 1 mixture of butyl acetate and xylene, resulting in a transparent coating composition 1.

[0144] (Examples 1-9 and Comparative Example 1)

[0145] The resistivity and viscosity of the obtained coating composition were determined using the following method, and the adhesion to the object being rotated was evaluated. The results are shown in Table 1.

[0146] resistance value

[0147] The resistance value was measured using an instrument manufactured by Ransburg and marketed as a "Megohm Tester".

[0148] Viscosity

[0149] The viscosity of the coating composition at a temperature of 23°C was determined using a Ford cup of size 4.

[0150] The coating composition adheres to the object around the outer periphery of the rotating head.

[0151] On a matte steel plate measuring 30 cm long, 40 cm wide, and 0.8 mm thick after zinc phosphate formation treatment, a cationic electrodeposition coating composition "V-50" (manufactured by Nippon Paint Automotive Coatings) was applied to achieve a cured film thickness of approximately 20 μm. The plate was then cured at 160°C for 30 minutes. A rotary atomizing electrostatic coating apparatus was then used to apply the coating to intermediate coating compositions 1-9, or a comparison of intermediate coating composition, base coat composition 1, and clear coat composition 1, resulting in a cured film thickness of approximately 25 μm. The outer circumference of the coated rotary head was visually inspected and evaluated according to the following criteria. Criteria A, B, and C are considered acceptable.

[0152] A: No adhesion of the coating composition to the outer periphery of the rotating head was confirmed.

[0153] B: Very little coating composition was found to adhere to the outer periphery of the rotating head.

[0154] C: A small amount of coating composition was confirmed to adhere to the outer periphery of the rotating head.

[0155] D: Significant adhesion of the coating composition to the outer periphery of the rotating head was confirmed.

[0156] [Table 1]

[0157] Industrial applicability

[0158] According to the present invention, a coating composition for a rotary atomizing electrostatic coating apparatus can be provided, which can suppress coating adhesion to the object and improve coating efficiency. According to the present invention, a coating film using the coating composition described above can be provided. According to the present invention, a vehicle having the coating film described above can be provided.

Claims

1. A coating composition for a rotary atomizing electrostatic coating device, characterized in that, The rotary atomizing electrostatic coating device does not use forming air in the micronization of the coating composition. The resistivity of the coating composition is 0.02 to 1.5 MΩ.

2. The coating composition for the rotary atomizing electrostatic coating device according to claim 1, wherein, Relative to the total mass of the coating composition, the coating composition contains 0.5% by mass or more of one or more selected from the group consisting of methanol, ethanol, 1-propanol, diethyl ether and capped isocyanates.

3. The coating composition for a rotary atomizing electrostatic coating device according to claim 1, wherein, The coating composition contains a compound having a dielectric constant of 3.0 F / m or higher. The compound is a capped isocyanate. The mass percentage of the compound relative to the total mass of the coating composition is 0.5% by mass or more.

4. The coating composition for a rotary atomizing electrostatic coating device according to claim 3, wherein, The terminated isocyanate is a terminated isocyanate of 1,6-hexamethylene diisocyanate.

5. The coating composition for a rotary atomizing electrostatic coating apparatus according to claim 1, wherein, The coating composition contains a compound having a dielectric constant of 3.0 F / m or higher. The compound is selected from one or more compounds chosen from the group consisting of methanol, ethanol, 1-propanol, and diethyl ether. The mass percentage of the compound relative to the total mass of the coating composition is 0.5% by mass or more.

6. The coating composition for a rotary atomizing electrostatic coating apparatus according to claim 1, wherein, The resistance value is 0.02 to 1.0 MΩ.

7. The coating composition for a rotary atomizing electrostatic coating apparatus according to claim 1, wherein, The coating composition is a coating composition used to form a coating film on the exterior of a vehicle.

8. The coating composition for a rotary atomizing electrostatic coating apparatus according to claim 1, wherein, The coating composition is a coating composition used to form a mid-coat film on the exterior of a vehicle.

9. A coating film, wherein, The coating uses the coating composition for a rotary atomizing electrostatic coating apparatus as described in claim 1.

10. A vehicle, wherein, The vehicle has the coating as described in claim 9.

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