Coating composition for rotary atomization-type electrostatic coating device, coating film, and vehicle

Abstract

To provide a coating composition for a rotary atomization-type electrostatic coating device, wherein it is possible to suppress undesired paint wraparound and improve coating efficiency.SOLUTION: This coating composition for a rotary atomization-type electrostatic coating device is characterized in that the rotary atomization-type electrostatic coating device does not use shaping air to atomize the coating composition, and the coating composition has an electrical resistance value of 0.02-1.5 MΩ.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a coating composition for use in a rotary atomizer electrostatic coating device, a coating film, and a vehicle. [Background technology]

[0002] Conventionally, there is known a coating device that atomizes (also called mist) the paint by blowing shaping air onto the paint discharged from a bell cup. This type of coating device has the drawback that the accompanying flow of the shaping air is reflected by the workpiece, causing the atomized paint to fly up, resulting in a decrease in coating efficiency.

[0003] In response to this, a rotary atomization electrostatic coating device that does not use shaping air has been proposed (see, for example, Patent Document 1). The coating device in Patent Document 1 is configured to release thread-like paint from grooves in a rotary head, and the thread-like paint is electrostatically atomized. The electrostatically atomized paint then adheres to an earthed workpiece (electrical conductor) by electrostatic force, and is coated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2019-055345 Summary of the Invention [Problem to be solved by the invention]

[0005] However, Patent Document 1 focuses only on the diameter of the paint filaments, and does not focus on the properties and composition of the paint itself.

[0006] In addition, the inventors have found that when paint used in a conventional coating device using shaping air is applied by the rotary atomization electrostatic coating device of Patent Document 1, part of the electrostatically atomized paint discharged from the rotary head does not adhere to the object to be coated, but adheres to the outer periphery of the rotary head, which is not the object to be coated, and coating efficiency is reduced. In this case, the paint that adhered to the outer periphery of the rotary head may scatter and adhere to the object to be coated, damaging the appearance of the object. Furthermore, when the paint adheres to an object that is not the object to be coated (also called "paint adhesion"), not only does the coating efficiency decrease, but there is also the disadvantage that unnecessary steps and costs are incurred, such as curing the object that is not the object to be coated, removing the paint that has adhered to the object that is not the object to be coated, and cleaning or replacing the object that is not the object to be coated.

[0007] Therefore, an object of the present invention is to provide a coating composition for use in a rotary atomizer type electrostatic coating device that is capable of suppressing coating adhesion and increasing coating efficiency.

[0008] Another object of the present invention is to provide a coating film using such a coating composition.

[0009] Another object of the present invention is to provide a vehicle having such a coating. [Means for solving the problem]

[0010] The coating composition according to the present invention is a coating composition for a rotary atomizer type electrostatic coating device, The rotary atomizer electrostatic coating device does not use shaping air to atomize the coating composition, The coating composition for a rotary atomizer type electrostatic coating device is characterized in that the coating composition has an electric resistance value of 0.02 to 1.5 MΩ, which makes it possible to suppress the coating adhesion and increase the coating efficiency.

[0011] In one embodiment of the coating composition according to the present invention, the coating composition contains at least one selected from the group consisting of methanol, ethanol, 1-propanol, diethyl ether and blocked isocyanate in an amount of at least 0.5 mass% based on the total mass of the coating composition.

[0012] In one embodiment of the coating composition according to the present invention, the coating composition comprises a compound having a dielectric constant of 3.0 F / m or more, the compound is a blocked isocyanate, The mass ratio of the compound to the total mass of the coating composition is 0.5 mass % or more.

[0013] In one embodiment of the coating composition according to the present invention, the blocked isocyanate is a blocked isocyanate of 1,6-hexamethylene diisocyanate.

[0014] In one embodiment of the coating composition according to the present invention, the coating composition comprises a compound having a dielectric constant of 3.0 F / m or more, the compound is one or more selected from the group consisting of methanol, ethanol, 1-propanol, and diethyl ether; The mass ratio of the compound to the total mass of the coating composition is 0.5 mass% or more.

[0015] In one embodiment of the coating composition according to the present invention, the electrical resistance value is 0.02 to 1.0 MΩ.

[0016] In one embodiment of the coating composition according to the present invention, the coating composition is a coating composition for forming a coating film on an outer panel of a vehicle.

[0017] In one embodiment of the coating composition according to the present invention, the coating composition is a coating composition for forming an intermediate coating film on an outer panel of a vehicle.

[0018] The coating film according to the present invention is a coating film that uses the coating composition for the rotary atomizer type electrostatic coating device.

[0019] The vehicle according to the present invention is a vehicle having the above-mentioned coating film. Effect of the Invention

[0020] According to the present invention, it is possible to provide a coating composition for a rotary atomizer type electrostatic coating device that can suppress coating adhesion and increase coating efficiency. According to the present invention, it is possible to provide a coating film using such a coating composition. According to the present invention, it is possible to provide a vehicle having such a coating film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, embodiments of the present invention will be described. These descriptions are intended to be illustrative of the present invention and are not intended to limit the present invention in any way.

[0022] In the present invention, two or more embodiments can be combined in any manner.

[0023] In this specification, unless otherwise specified, any numerical range is intended to include the upper and lower limits of the range, for example, 0.02 to 1.5 MΩ means 0.02 MΩ or more and 1.5 MΩ or less.

[0024] In the present invention, the paint and the paint composition can be used interchangeably.

[0025] (Paint composition for rotary atomizer electrostatic coating device) The coating composition according to the present invention is a coating composition for a rotary atomizer type electrostatic coating device, The rotary atomizer electrostatic coating device does not use shaping air to atomize the coating composition, The coating composition for use in a rotary atomizer type electrostatic coating device is characterized in that the coating composition has an electric resistance value of 0.02 to 1.5 MΩ.

[0026] As a result of investigations, the present inventors have found that in a rotary atomization electrostatic coating device that does not use shaping air to atomize a coating composition, by setting the electrical resistance value of the coating composition to 0.02 to 1.5 MΩ, it is possible to suppress paint adhesion and increase coating efficiency.

[0027] The electrical resistance of the coating composition of the present invention is 0.02 to 1.5 MΩ. If the electrical resistance is less than 0.02 MΩ, the droplets of the coating composition cannot be sufficiently charged. If the electrical resistance is more than 1.5 MΩ, the adhesion of the coating composition cannot be suppressed.

[0028] In one embodiment, the electrical resistance 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. In another embodiment, the electrical resistance 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.

[0029] In one embodiment of the coating composition according to the present invention, the electrical resistance is 0.02 to 1.0 MΩ. As a result of further investigation by the present inventor, it was found that in the case of a rotary atomization electrostatic coating apparatus in which the voltage applied to the rotary head is controlled by a voltage generator to keep the current flowing between the rotary head and the workpiece constant, as described in paragraph

[0038] of Patent Document 1 (hereinafter sometimes referred to as a "voltage-controlled constant current type apparatus"), if the electrical resistance of the coating composition is high, a high voltage is applied to the rotary atomization electrostatic coating apparatus to keep the current constant, and the coating apparatus may abnormally stop. When the coating apparatus abnormally stops, unnecessary work or loss of raw materials occurs, such as identifying the cause of the stop, removing the cause of the stop, discarding or repainting defective coated products due to uneven coating caused by the stop, and restarting the coating apparatus, and productivity decreases. In contrast, by setting the electrical resistance of the coating composition to 0.02 to 1.0 MΩ, it is possible to prevent high voltage from being applied to the coating apparatus, suppress abnormal stopping of the coating apparatus, and perform stable coating.

[0030] The method for controlling the electrical resistance value of the coating composition of the present invention to the range of 0.02 to 1.5 MΩ is not particularly limited, but may be, for example, blending one or more selected from the group consisting of methanol, ethanol, 1-propanol, diethyl ether, and blocked isocyanates. Examples of blocked isocyanates include blocked isocyanates of 1,6-hexamethylene diisocyanate. In addition, examples of commercially available blocked isocyanates include products manufactured by Baxenden under the trade name "7961" and products manufactured by Asahi Kasei under the trade names "Duranate SBB-70P" and "Duranate MFK-60B".

[0031] The amount of one or more selected from the group consisting of methanol, ethanol, 1-propanol, diethyl ether, and blocked isocyanate is, for example, 0.5 mass% or more based on 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 blocked isocyanate is 0.5 to 10 mass% based on the total mass of the coating composition.

[0032] In one embodiment of the coating composition according to the present invention, the coating composition contains at least one selected from the group consisting of methanol, ethanol, 1-propanol, diethyl ether and blocked isocyanate in an amount of at least 0.5 mass% based on the total mass of the coating composition.

[0033] Alternatively, an example of a method for controlling the electrical resistance value of the coating composition of the present invention to within the range of 0.02 to 1.5 MΩ is to blend a compound having a certain dielectric constant.

[0034] In one embodiment of the coating composition according to the present invention, the coating composition comprises a compound having a dielectric constant of 3.0 F / m or more, The mass ratio of the compound to the total mass of the coating composition is 0.5 mass % or more, which makes it easier to control the electrical resistance value of the coating composition of the present invention to the range of 0.02 to 1.5 MΩ.

[0035] Examples of compounds having a dielectric constant of 3.0 F / m or more (hereinafter, simply referred to as "predetermined compounds") include alcohol solvents such as 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.

[0036] Other examples of the predetermined compound include diethyl ether (dielectric constant: 4.2 F / m) and blocked isocyanate.

[0037] In one embodiment of the coating composition according to the present invention, the coating composition comprises a compound having a dielectric constant of 3.0 F / m or more, the compound is a blocked isocyanate, The mass ratio of the compound to the total mass of the coating composition is 0.5 mass % or more.

[0038] In one embodiment of the coating composition according to the present invention, the blocked isocyanate is a blocked isocyanate of 1,6-hexamethylene diisocyanate.

[0039] In one embodiment of the coating composition according to the present invention, the coating composition comprises a compound having a dielectric constant of 3.0 F / m or more, the compound is one or more selected from the group consisting of methanol, ethanol, 1-propanol, and diethyl ether; The mass ratio of the compound to the total mass of the coating composition is 0.5 mass % or more.

[0040] In the coating composition according to the present invention, from the viewpoint of reducing VOCs derived from the coating composition, it is preferable that the specified compound is not an alcohol-based solvent.

[0041] In one embodiment of the coating composition according to the present invention, the predetermined compound is a blocked isocyanate.

[0042] The predetermined compounds may be used alone or in combination of two or more.

[0043] By making the mass ratio of the predetermined compound 0.5 mass% or more relative to the total mass of the coating composition of the present invention, the electrical resistance value of the coating composition of the present invention can be easily controlled in the range of 0.02 to 1.5 MΩ. In one embodiment, the mass ratio of the predetermined compound relative to the total mass of the coating composition of the present invention is 0.5 to 10 mass%.

[0044] The coating composition of the present invention may contain other components such as resins, crosslinking agents, pigments, solvents (solvents other than the specified compounds), pigment dispersants, anti-sagging agents, viscosity modifiers, anti-settling agents, reaction accelerators, crosslinking accelerators, curing agents, leveling agents, surface conditioners, defoamers, plasticizers, preservatives, antifungal agents, UV stabilizers, etc. These optional components may be used alone or in combination of two or more.

[0045] Resin components The resin component may be a resin component of a conventionally known coating composition. Examples of the resin component include polyester resin, melamine resin, epoxy resin, acrylic resin, alkyd resin, fluororesin, polyurethane resin, polyether resin, and modified products thereof. In addition, polymer compounds containing inorganic components or consisting of inorganic components, such as silicone resin and alkoxysilane condensate, may also be used as the resin component. The resin component may be used alone or in combination of two or more.

[0046] The content of the resin component is not particularly limited and may be appropriately adjusted.

[0047] The resin component preferably has a curable functional group that reacts with the crosslinking agent. Any functional group that reacts with the crosslinking agent may be used, and examples of such functional groups include hydroxyl groups, carboxyl groups, and epoxy groups. The curable functional group of the resin component used in the coating composition of the present invention is preferably a hydroxyl group, since it can react with a blocked isocyanate compound having a dielectric constant in a specific range.

[0048] Crosslinking agent The crosslinking agent can be selected according to the curable functional group of the resin component. For example, the crosslinking agent can be a carbodiimide compound, a hydrazine compound, an amino resin, a polyisocyanate compound, a blocked polyisocyanate compound, an amine compound, a polyamide compound, and a polycarboxylic acid compound. The crosslinking agent can be used alone or in combination of two or more.

[0049] As the crosslinking agent used in the coating composition of the present invention, it is preferable to use a blocked isocyanate compound having a dielectric constant in a specific range. Such a blocked isocyanate compound may be used in combination with other crosslinking agents.

[0050] The isocyanate compound (1) may be an alicyclic, aromatic group-containing aliphatic or aromatic compound. Examples of suitable isocyanate compounds include diisocyanates and their isocyanurates (trimers of diisocyanates).

[0051] As the diisocyanate, for example, a diisocyanate having 5 to 24, preferably 6 to 18, carbon atoms can be used.

[0052] For example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexane diisocyanate, undecane diisocyanate-(1,11), lysine ester diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (IPDI), 4,4'-diisocyanatodicyclomethane, ω,ω'-dipropyl ether diisocyanate, thiodipropyl diisocyanate, cyclohexyl-1,4-diisocyanate, socyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,5-dimethyl-2,4-bis(isocyanatomethyl)benzene, 1,5-trimethyl-2,4-bis(ω-isocyanatoethyl)-benzene, 1,3,5-trimethyl-2,4-bis(isocyanatomethyl)benzene, 1,3,5-triethyl-2,4-bis(isocyanatomethyl)benzene, dicyclohexyldimethylmethane-4,4'-diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate and diphenylmethane-4,4'-diisocyanate.

[0053] Also usable are aromatic diisocyanates such as 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenylmethane, 1,4-diisocyanatoisopropylbenzene, cyclohexyl-1,4-diisocyanate, toluene diisocyanate and hexamethylene diisocyanate. Mixtures of these compounds can also be used.

[0054] The isocyanurate may be a trimer of the above-mentioned diisocyanates, and the isocyanate may be a mixture of diisocyanates or trimers.

[0055] Melamine Resin The melamine resin is not particularly limited and may be the same as or different from the melamine resin (ii) contained in the above intermediate coating composition. As the melamine resin, for example, methylated melamine resin, butylated melamine resin, or methyl / butyl mixed type melamine resin can be used. For example, "Cymel-303" and "Cymel 254" manufactured by Nippon Cytec Industries, "Uban 20N60" and "Uban 128" manufactured by Mitsui Chemicals, and "Sumimal Series" manufactured by Sumitomo Chemical Co., Ltd. can be mentioned.

[0056] The amount of the melamine resin used is preferably 10 to 40% by mass based on the solid content of the film-forming resins such as urea-modified acrylic resin, urethane-modified polyester resin, and melamine resin. More preferably, it is 15 to 35% by mass. When the amount of the melamine resin used is 10% by mass or more, the curability is enhanced. Also, when the amount of the melamine resin used is 40% by mass or less, the chipping property of the coating film becomes better.

[0057] · Pigment The pigment is not particularly limited, and known pigments for paints can be used. Examples of the pigment include coloring pigments such as titanium dioxide, carbon black, iron oxide red, and phthalocyanine blue; extender pigments such as precipitated barium sulfate, calcium carbonate, talc, mica, and kaolin; rust preventive pigments; and infrared reflective pigments. The pigments may be used alone or in combination of two or more.

[0058] Lustrous pigment The shape of the lustrous pigment is not particularly limited. The lustrous pigment may be colored. As the lustrous pigment, for example, flaky ones having an average particle size (D50) of 2 to 50 μm and a thickness of 0.1 to 5 μm are preferable. Also, those having an average particle size in the range of 10 to 35 μm are excellent in luster and are more preferably used.

[0059] The pigment concentration (PWC) of the luster pigment in the coating composition is, for example, 1 to 23.0%. If the PWC of the luster pigment is 23% or less, the appearance of the coating film tends to be better. The PWC of the luster pigment is preferably 1.5% to 20.0%, and more preferably 2.0% to 18.0%. The pigment concentration (PWC) indicates the pigment content (%) based on the resin solid mass.

[0060] Examples of the luster pigment include uncolored or colored metallic luster materials such as metals or alloys, and mixtures thereof, interference mica powder, colored mica powder, white mica powder, graphite, or colorless or colored flat pigments. Uncolored or colored metallic luster materials such as metals or alloys, and mixtures thereof, interference mica powder, colored mica powder, and white mica powder are preferred because they have excellent dispersibility and can form a highly transparent coating film. Specific examples of metals include aluminum, aluminum oxide, copper, zinc, iron, nickel, and tin.

[0061] Furthermore, if necessary, a coloring pigment may be contained. Examples of the coloring pigment include the coloring pigments and inorganic pigments described in the description of the intermediate coating composition. Furthermore, calcium carbonate, barium sulfate, clay, talc, etc. may be used in combination as an extender pigment.

[0062] The total pigment concentration (PWC) in the metallic coating composition, including the luster pigment 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 film appearance tends to be better.

[0063] ·solvent The solvent may be appropriately selected from solvents for conventionally known coating compositions. For example, 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); ethylene glycol, diethyl ether ... Examples of suitable solvents include glycols such as ethylene glycol, propylene glycol, dipropylene glycol, 1,3-butylene glycol, pentamethylene glycol, and 1,3-octylene glycol; amides such as formamide, N-methylformamide, dimethylformamide (DMF), dimethylacetamide, dimethylsulfoxide (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 halogenated solvents such as chloroform and dichloromethylene.

[0064] The coating composition of the present invention, in one embodiment, is a solvent-based coating.

[0065] ·Applications The coating composition of the present invention can be used in known coating applications as long as it is used in a rotary atomization electrostatic coating device.The applications of the coating composition of the present invention include, for example, the intermediate coating paint, topcoat base coating paint, and topcoat clear coating paint for the outer panels of vehicles such as automobiles, motorcycles, trains, buses, trucks, and taxis; the intermediate coating paint, topcoat base coating paint, and topcoat clear coating paint for vehicle parts; aircraft such as airplanes and helicopters; home appliances such as refrigerators, washing machines, and televisions; computer equipment such as personal computers and smartphones; building materials such as steel doors, steel sashes, steel shutters, storage sheds, fences, stairs, guardrails, and doorknobs; hot water gas appliances such as meter boxes, ventilation fans, and water heaters; steel furniture such as lockers, cabinets, partitions, and racks; cast iron pipes such as valves; intermediate coating paints, topcoat base coating paints, and topcoat clear coating paints for the outer panels of castings such as conveyors, chain blocks, and manhole covers.

[0066] In one embodiment of the coating composition according to the present invention, the coating composition is a coating composition for forming a coating film on an outer panel of a vehicle.

[0067] In one embodiment of the coating composition according to the present invention, the coating composition is a coating composition for forming an intermediate coating film on an outer panel of a vehicle.

[0068] The substrate to be coated with the coating composition is not particularly limited as long as it can be coated with a rotary atomizer type electrostatic coating device, and can be appropriately selected. Examples of the substrate include metals such as steel plate, iron, aluminum, and copper; glass, plastic, and wood with a metal thin film or conductive thin film formed on the surface. The substrate may be subjected to a zinc plating treatment, a chemical conversion treatment, an electrodeposition treatment, and the like.

[0069] The rotary atomization electrostatic coating device using the coating composition for rotary atomization electrostatic coating device of the present invention may be a known rotary atomization electrostatic coating device, such as the coating device of Patent Document 1. The rotary atomization electrostatic coating device may be a voltage-controlled constant current type device, or a current-controlled constant voltage type (a rotary atomization electrostatic coating device that controls the current applied to the rotary head to keep constant the voltage flowing between the rotary head and the workpiece).

[0070] In one embodiment, the rotary atomizer electrostatic spraying device using the coating composition of the present invention is a voltage controlled constant current type device.

[0071] Method for preparing coating composition The method for preparing the coating composition is not particularly limited, except that the coating composition has an electrical resistance value of 0.02 to 1.5 MΩ, and the coating composition can be prepared by mixing the components by a conventionally known method.

[0072] (Paint film) The coating film according to the present invention is a coating film that uses the coating composition for the rotary atomizer type electrostatic coating device.

[0073] The thickness of the coating film after drying is not particularly limited and may be appropriately adjusted. For example, the thickness of the coating film after drying is 5 to 50 μm. In one embodiment, the thickness of the coating film after drying is 25 to 40 μm. In another embodiment, the thickness of the coating film after drying is 30 to 35 μm.

[0074] In one embodiment, the coating of the present invention is an undercoat coating for vehicle exterior panels. In another embodiment, the coating of the present invention is a topcoat basecoat for vehicle exterior panels. In another embodiment, the coating of the present invention is a clear topcoat for the exterior panels of a vehicle. In another embodiment, the coating of the present invention is an intermediate coating for automotive exterior panels. In another embodiment, the coating of the present invention is a topcoat basecoat for automotive exterior panels. In another embodiment, the coating of the present invention is a clear topcoat for automotive exterior panels.

[0075] -How to prepare the coating The method for producing the coating film is not particularly limited, except that the coating composition for a rotary atomization type electrostatic coating device of the present invention is used to coat the coating film using a rotary atomization type electrostatic coating device. For example, a coating method such as a conventionally known method for forming a multi-layer coating film or baking can be used.

[0076] The drying temperature after application of the coating composition for use in a rotary atomizer electrostatic coating device of the present invention may be appropriately adjusted depending on the solvent, coating environment, etc. For example, in the case of a drying time of 20 to 30 minutes, the drying temperature is 140 to 150°C.

[0077] Examples of articles having the coating film of the present invention include, but are not limited to, vehicles such as automobiles, motorcycles, trains, buses, trucks, and taxis; vehicle parts; aircraft such as airplanes and helicopters; home appliances such as refrigerators, washing machines, and televisions; computer equipment such as personal computers and smartphones; building materials such as steel doors, steel sashes, steel shutters, storerooms, fences, stairs, guardrails, and doorknobs; hot water gas appliances such as meter boxes, ventilation fans, and water heaters; steel furniture such as lockers, cabinets, partitions, and racks; cast iron pipes such as valves; and castings such as conveyors, chain blocks, and manhole covers.

[0078] The coating film of the article of the present invention may be only one or more of the coating films of the present invention, or the coating film of the article may be one or more of the coating films of the present invention and one or more of the coating films made of known coating compositions.

[0079] (vehicle) The vehicle according to the present invention is a vehicle having the above coating film. The vehicle is not particularly limited and can be appropriately selected from known vehicles. Examples of the vehicle include automobiles, motorcycles, trains, buses, trucks, taxis, truck cranes, trailers, garbage trucks, tanks, and other specialized vehicles.

[0080] The coating film of the vehicle of the present invention may be only one or more coating films of the present invention, while the coating film of the article may be one or more coating films using a known paint composition in addition to one or more coating films of the present invention. EXAMPLES

[0081] The present invention will be described in more detail below by way of examples. However, these examples are intended to illustrate the present invention and are not intended to limit the present invention in any way.

[0082] The materials used in the examples are as follows: Prescribed compound 1: blocked isocyanate, trade name "7961" manufactured by Baxenden, indicated as "7961" in Table 1 Specified compound 2: blocked isocyanate, trade name "Duranate MFK-60B" manufactured by Asahi Kasei Corporation, indicated as "MFK-60B" in Table 1 Prescribed compound 3: Ethanol Specified compound 4: Diethyl ether

[0083] Production Example 1: Production of urethane-modified polyester resin for intermediate coating composition In a 2L reaction vessel equipped with a cooling tube equipped with a nitrogen inlet tube, a stirrer, a temperature controller, a dropping funnel and a decanter, 440 parts by mass of isophthalic acid, 20 parts by mass of hexahydrophthalic acid, 40 parts by mass of azelaic acid, 300 parts by mass of trimethylolpropane and 200 parts by mass of neopentyl glycol were charged, and when the raw materials were dissolved by heating and became stirrable, 0.2 parts by mass of dibutyltin oxide was added, stirring was started, and the reaction layer temperature was gradually raised from 180 to 220 ° C. over 3 hours. The condensation water generated was distilled out of the system. When the temperature reached 220 ° C., it was kept warm for 1 hour, and 20 parts by mass of xylene was gradually added to the reaction layer, and the condensation reaction was allowed to proceed in the presence of the solvent. When the resin acid value reached 10 mg KOH / g, it was cooled to 100 ° C., and 100 parts by mass of hexamethylene diisocyanate was gradually added over 30 minutes. After further holding for 1 hour, 200 parts by mass of xylene and 200 parts by mass of butyl acetate were added to obtain a urethane-modified polyester resin with a solid content of 70%, a number average molecular weight of 2000, an acid value of 8 mg KOH / g (solid content), a hydroxyl value of 120 (solid content), and a resin Tg of 60°C.

[0084] Production Example 2: Production of non-aqueous dispersion for intermediate coating composition (a) Manufacture of dispersion stabilizing resin 90 parts by mass of butyl acetate was charged into a vessel equipped with a stirrer, a temperature control device, and a reflux condenser. Next, 20 parts by mass of a solution composed of 38.9 parts by mass of methyl methacrylate, 38.8 parts by mass of stearyl methacrylate, 22.3 parts by mass of 2-hydroxyethyl acrylate, and 5.0 parts by mass of azobisisobutyronitrile was added, and the mixture was heated with stirring to increase the temperature. At 110°C, the remaining 85 parts by mass of the above mixed solution was dripped over 3 hours, and then a solution composed of 0.5 parts by mass of azobisisobutyronitrile and 10 parts by mass of butyl acetate was dripped over 30 minutes. The reaction solution was stirred and refluxed for another 2 hours to increase the conversion rate to resin, and then the reaction was terminated to obtain an acrylic resin with a solid content of 50% and a number average molecular weight of 5600.

[0085] (b) Preparation of non-aqueous dispersion 90 parts by mass of butyl acetate and 120 parts by mass of the acrylic resin obtained in the above (a) production of dispersion-stabilizing resin (60 parts by mass as solids) were added to a container equipped with a stirrer, a cooler, and a temperature control device. Next, a solution consisting of 7.0 parts by mass of styrene, 1.8 parts by mass of methacrylic acid, 12.0 parts by mass of methyl methacrylate, 8.5 parts by mass of ethyl acrylate, 40.7 parts by mass of 2-hydroxyethyl acrylate, and 1.4 parts by mass of azobisisobutyronitrile was dropped at 100°C for 3 hours, and then a solution consisting of 0.1 parts by mass of azobisisobutyronitrile and 1 part by mass of butyl acetate was dropped for 30 minutes. When the reaction solution was further stirred for 1 hour, an emulsion with a solid content of 60% and a particle diameter of 180 nm was obtained. This emulsion was diluted with butyl acetate to obtain a core-shell type butyl acetate dispersion with a viscosity of 300 cps (25°C), a particle diameter of 180 nm, and a non-aqueous dispersion content of 40% by mass. This non-aqueous dispersion resin had a Tg of 23° C. and a hydroxyl value of 162 (solid content).

[0086] Production Example 3: Production of intermediate coating composition 1 In a 1L vessel, 107 parts by mass of the urethane-modified polyester resin varnish for intermediate coating composition obtained in the previous manufacturing example, 280 parts by mass of CR-97 (titanium oxide manufactured by Ishihara Sangyo Kaisha), 13 parts by mass of MA-100 (carbon black pigment manufactured by Mitsubishi Chemical Corporation), 7 parts by mass of LMS-100 (flake talc manufactured by Fuji Talc Co., Ltd.), 47 parts by mass of butyl acetate, and 47 parts by mass of xylene were charged, and the same amount of GB503M (glass beads with a particle size of 1.6 mm) was added, and the mixture was dispersed at room temperature for 3 hours using a benchtop sand grinder mill to obtain a gray pigment paste. The particle size at the end of dispersion measured by a grind gauge was 5 μm or less. The glass beads were filtered to obtain a pigment paste.

[0087] 100 parts by mass of the above pigment paste was mixed with 130 parts by mass of the above urethane-modified polyester resin for intermediate coating composition, 53 parts by mass of the above nonaqueous dispersion for intermediate coating composition, 71 parts by mass of U-BAN 128 (a melamine resin manufactured by Mitsui Chemicals, Inc., solids content 60%), 0.5 parts by mass of blocked isocyanate "7961" (manufactured by Baxenden), and 6.7 parts by mass of blocked isocyanate "Duranate MFK-60B" (manufactured by Asahi Kasei Corporation, solids content **%).

[0088] The mixture was then diluted with a No. 4 Ford cup using a 1 / 1 mixed solvent of ethoxyethyl propionate / S-100 (aromatic hydrocarbon solvent manufactured by Exxon Corp.) to 19 seconds / 20°C to prepare intermediate coating composition 1. The non-volatile content at the time of application was 49%.

[0089] (Production Examples 4 to 11: Production of Intermediate Coating Compositions 2 to 9) Intermediate coating compositions 2 to 9 were prepared in the same manner as in Preparation Example 3, except that the amounts of the two types of blocked isocyanates and the amount of ethanol or diethyl ether in intermediate coating composition 1 were changed as shown in Table 1.

[0090] (Production Example 12: Production of Comparative Intermediate Coating Composition) Comparative intermediate coating compositions were prepared in the same manner as in Preparation Example 3, except that the amounts of the two blocked isocyanates in intermediate coating composition 1 were changed as shown in Table 1.

[0091] (Production Example 13: Production of urethane-modified polyester resin for base coating composition) In a 2L reaction vessel equipped with a cooling tube equipped with a nitrogen inlet tube, a stirrer, a temperature controller, a dropping funnel and a decanter, 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 charged, and when the raw materials were dissolved by heating and became stirrable, 0.2 parts by mass of dibutyltin oxide was added, stirring was started, and the reaction layer temperature was gradually raised from 180 to 220 ° C. over 3 hours. The condensation water generated was distilled out of the system. When it reached 220 ° C., it was kept warm for 1 hour, and 20 parts by mass of xylene was gradually added to the reaction layer, and the condensation reaction was allowed to proceed in the presence of the solvent. When the resin acid value reached 8 mg KOH / g, it was cooled to 100 ° C., and 10 parts by mass of hexamethylene diisocyanate was gradually added over 30 minutes. After further holding for 1 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 urethane-modified polyester resin with a solid content of 70%, a number average molecular weight of 1,800, a weight average molecular weight of 10,000, an acid value of 6 mg KOH / g (solid content) and a hydroxyl value of 100 (solid content).

[0092] (Production Example 14: Production of acrylic resin for base coating composition) A 1L reaction vessel equipped with a cooling tube equipped with a nitrogen inlet tube, a stirrer, a temperature controller, a dropping funnel and a decanter was charged with 50 parts by mass of xylene and 14 parts by mass of n-butanol, and the temperature was set to 110 ° C. Next, a solution of 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 t-butylperoxy-2-ethylhexanoate was dropped over 3 hours. Next, a solution consisting of 1.0 parts by mass of t-butylperoxy-2-ethylhexanoate and 6 parts by mass of xylene was dropped over 30 minutes, and then the temperature was maintained at 110 ° C. for another hour. An acrylic resin with a solid content of 60%, an acid value of 20 mg KOH / g (solid content), a hydroxyl value of 75 (solid content) and a number average molecular weight of 5000 was obtained.

[0093] (Production Example 15: Production of Solvent-Based Metallic Base Coating Composition) Into a stainless steel container, 75 parts by mass of AS-9606 (urea-modified acrylic resin manufactured by Mitsubishi Rayon Co., Ltd., urea modification amount 6.5%, acid value 12 mgKOH / g (solid content), hydroxyl value 70 (solid content), weight average molecular weight 7000, Tg 16°C), 14.3 parts by mass of the urethane-modified polyester for the base coating composition of Production Example 13, 25 parts by mass of the acrylic resin for the base coating composition of Production Example 14, 2.9 parts by mass of Cyanine Blue G-314 (blue pigment manufactured by Sanyo Dye Co., Ltd.) and Varifine were added. 33.9 parts by mass of a pigment dispersion paste obtained by dispersing 6.0 parts by mass of BF-40 (barium sulfate pigment manufactured by Sakai Chemical Co., Ltd.) so that the particle size of each was 5 μm or less, 50 parts by mass of U-BAN 20N60 (butylated melamine resin manufactured by Mitsui Chemicals, Inc., solids content 60%), and 11.6 parts by mass of Aluminum Paste 7640NS (aluminum pigment manufactured by Toyo Aluminum K.K.) were weighed and stirred with a tabletop stirrer to prepare a light blue solvent-based metallic base paint composition (PWC 17.0%).

[0094] Next, the above solvent-based metallic base paint composition was diluted with a dilution thinner consisting of 10 parts by mass of Solvesso 150 (a hydrocarbon solvent manufactured by Exxon Oil), 40 parts by mass of ethyl acetate, 40 parts by mass of toluene, and 10 parts by mass of butyl acetate in a No. 4 Ford cup to 12.5 seconds / 20°C to obtain base paint composition 1.

[0095] (Production Example 16: Synthesis of acid anhydride group-containing acrylic resin (component (A)) A reaction vessel equipped with a thermometer, a stirrer, a cooling pipe, a nitrogen inlet pipe, and a dropping funnel was charged with 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 ExxonMobil), and the temperature was raised to 130°C. Using the 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-ethylhexyl acrylate, 18 parts by mass of maleic anhydride, 2.57 parts by mass of acrylic acid, 8.5 parts by mass of t-butyl peroxy 2-ethylhexanoate, and 5.2 parts by mass of Solvesso 100 was added dropwise over 3 hours. After the addition was completed, the mixture was held at 130°C for 30 minutes, and then a solution consisting of 1 part by mass of t-butyl peroxy 2-ethylhexanoate and 2.2 parts by mass of Solvesso 100 was added dropwise over 30 minutes. After the addition of this solution was completed, the reaction was continued at 130°C for an additional 1 hour to obtain a varnish having a non-volatile content of 58% containing an acid anhydride group-containing acrylic resin having a number average molecular weight of 3100 and an acid anhydride group content of 1.84 mmol / g (solid content).

[0096] (Production Example 17: Synthesis of Carboxyl Group-Containing Polyester Resin (Component (a)) A reaction vessel equipped with a thermometer, a stirrer, a cooling pipe, and a nitrogen inlet pipe was charged with 8.85 parts by mass of pentaerythritol, 57.5 parts by mass of Placcel M (ε-caprolactone monomer manufactured by Daicel Corporation, trade name), 33.92 parts by mass of Rica Sid HH-A (hexahydrophthalic anhydride manufactured by Shin Nippon Rika Co., Ltd., trade name), and 0.1 part by mass of dibutyltin oxide, and the temperature was raised to 150°C. After holding at 150°C for 2 hours, 616 parts by mass of hexahydrophthalic anhydride, which had been heated and dissolved, was added, and after holding at 150°C for 1 hour, the mixture was cooled and diluted with 33.4 parts by mass of 3-ethoxyethyl propionate to obtain a varnish having a non-volatile content of 75% containing a carboxyl group-containing polyester resin having a number average molecular weight of 2500, a weight average molecular weight / number average molecular weight = 1.3, a carboxyl group content of 2.2 mmol / g (solid content), and a hydroxyl group content of 0.32 mmol / g (solid content).

[0097] (Production Example 18: Synthesis of acrylic resin containing hydroxyl groups and epoxy groups (component (C)) An autoclave equipped with a thermometer, a stirrer, a cooling tube, a nitrogen inlet tube, and a dropping funnel was charged with 23.7 parts by mass of 3-ethoxyethyl propionate, and the temperature was raised to 170° C. Using a liquid pump, 25 parts by mass of styrene, 30.3 parts by mass of glycidyl methacrylate, 8 parts by mass of n-butyl acrylate, 23.9 parts by mass of isobornyl acrylate, 12.8 parts by mass of 4-hydroxybutyl acrylate, and a solution consisting of 3.0 parts by mass of di-tert-amyl peroxide and 2.6 parts by mass of 3-ethoxyethyl propionate were dropped into the reaction tank over 3 hours.

[0098] After the dropwise addition, the mixture was held at 170°C for 30 minutes, and then a solution consisting of 0.4 parts by mass of di-tert-butyl peroxide and 1.5 parts by mass of 3-ethoxyethyl propionate was added dropwise over 30 minutes using a liquid pump. After the dropwise addition, the reaction was continued at 170°C for another hour, and a varnish containing an acrylic resin with a number average molecular weight of 2200, an epoxy group of 2.1 mmol / g (solid content), and a hydroxyl group of 0.9 mmol / g (solid content) and a non-volatile content of 76% was obtained.

[0099] (Production Example 19: Preparation of clear coating composition 1) A first package was prepared by mixing 32 g of the prepared acid anhydride group-containing acrylic resin (component (A)) as a resin solid content, 15 g of the prepared carboxyl group-containing polyester resin (component (B)) as a resin solid content, and 0.5 parts by mass of a tetrabutylammonium bromide curing catalyst in a stainless steel beaker.

[0100] On the other hand, 53 g of the prepared acrylic resin (component (c)) as resin solids, 2 parts by mass of the ultraviolet absorber "Tinuvin 900" manufactured by Ciba Specialty, 1 part by mass of the light stabilizer "Sanol LS-440" manufactured by Sankyo Machinery, and 0.1 parts by mass of the surface conditioner "Modaflow" manufactured by UCB were mixed to prepare the second package. If stored in this two-liquid state, there will be no reaction under room temperature conditions. The first and second packages obtained above were mixed immediately before use, and the viscosity was adjusted to 28 seconds in Ford Cup No. 4 with a mixed solvent consisting of butyl acetate / xylene = 1 / 1 to prepare clear coating composition 1.

[0101] (Examples 1 to 9 and Comparative Example 1) The electrical resistance and viscosity of the resulting coating composition were measured, and the adhesion to the rotary head was evaluated as follows. The results are shown in Table 1.

[0102] Electrical resistance value The electrical resistance value was measured using a "Mega Ohm Tester" manufactured by Ransberg Corporation.

[0103] ·viscosity The viscosity of the coating composition was measured at a coating composition temperature of 23° C. using a Ford Cup No. 4.

[0104] - Coating composition adheres to the outer circumference of the rotating head A cationic electrodeposition coating composition "V-50" (manufactured by Nippon Paint Automotive Coatings Co., Ltd.) was electrocoated onto a 30 cm long, 40 cm wide, 0.8 mm thick dull steel plate that had been subjected to zinc phosphate conversion treatment so that the cured film thickness was about 20 μm, and then heated at 160°C for 30 minutes to cure, and then intermediate coating compositions 1 to 9 or comparative intermediate coating compositions, base coating composition 1, and clear coating composition 1 were applied using a rotary atomization electrostatic coating device so that the cured film thickness was about 25 μm. The outer circumference of the rotating head after coating was visually observed and evaluated according to the following criteria. Criteria A, B, and C are acceptable. A: No adhesion of the coating composition to the outer periphery of the rotating head is observed. B: A very small amount of paint composition is found adhering to the outer periphery of the rotating head. C: A small amount of paint composition is found adhering to the outer periphery of the rotating head. D: Significant adhesion of the coating composition to the outer periphery of the rotating head is observed.

[0105] [Table 1] [Industrial Applicability]

[0106] According to the present invention, it is possible to provide a coating composition for a rotary atomizer type electrostatic coating device that can suppress coating adhesion and increase coating efficiency. According to the present invention, it is possible to provide a coating film using such a coating composition. According to the present invention, it is possible to provide a vehicle having such a coating film.

Claims

1. A coating composition for use in a rotary atomizer electrostatic coating device, comprising: The rotary atomizer electrostatic coating device does not use shaping air to atomize the coating composition, A coating composition for use in a rotary atomizer type electrostatic coating device, characterized in that the coating composition has an electric resistance value of 0.02 to 1.5 MΩ.

2. 2. The coating composition for a rotary atomization type electrostatic coating device according to claim 1, wherein the coating composition contains at least one selected from the group consisting of methanol, ethanol, 1-propanol, diethyl ether and blocked isocyanate in an amount of at least 0.5 mass% based on the total mass of the coating composition.

3. The coating composition contains a compound having a dielectric constant of 3.0 F / m or more, the compound is a blocked isocyanate, 2. The coating composition for use in a rotary atomizer type electrostatic coating device according to claim 1, wherein the mass ratio of said compound to the total mass of said coating composition is 0.5 mass % or more.

4. 4. The coating composition for use in a rotary atomizer electrostatic sprayer according to claim 3, wherein the blocked isocyanate is a blocked isocyanate of 1,6-hexamethylene diisocyanate.

5. The coating composition contains a compound having a dielectric constant of 3.0 F / m or more, the compound is one or more selected from the group consisting of methanol, ethanol, 1-propanol, and diethyl ether; 2. The coating composition for use in a rotary atomizer type electrostatic coating device according to claim 1, wherein the mass ratio of said compound to the total mass of said coating composition is 0.5 mass % or more.

6. 2. The coating composition for use in a rotary atomizer electrostatic coating device according to claim 1, wherein the electrical resistance value is 0.02 to 1.0 MΩ.

7. 2. The coating composition for use in a rotary atomizer electrostatic coating device according to claim 1, wherein the coating composition is for forming a coating film on an exterior panel of a vehicle.

8. 2. The coating composition for use in a rotary atomizer type electrostatic coating device according to claim 1, wherein the coating composition is a coating composition for forming an undercoat coating film on an exterior panel of a vehicle.

9. A coating film formed using the coating composition for use in a rotary atomizer type electrostatic coating device according to claim 1.

10. A vehicle having the coating film according to claim 9.

Images