JP6573773B2 - Vehicle paint composition - Google Patents

Description

  The present invention relates to a coating composition for vehicles, preferably a coating composition for vehicle repair, and in particular, to a coating composition for vehicles excellent in painting workability and drying property.

  In vehicles such as automobiles, a primer, a putty, and a surfacer are generally coated in order on a base material such as a metal plate to form an undercoat film, and then a metallic paint or enamel paint is applied on the undercoat film. A base coating film is formed, and a clear coating is applied as necessary to form a clear coating film. And when these coating films have defects, after removing the defective parts (coating films), the repair paints corresponding to the respective paints are sequentially applied onto the base material, The coating will be repaired.

  In coating compositions for vehicle repairs, in addition to cost, aromatic compounds such as xylene, toluene, and ethylbenzene are currently used as solvents from the viewpoint of coating workability, drying properties, and finish. Yes (for example, Patent Documents 1 and 2), a coating composition that does not use these aromatic compounds is desired for the purpose of reducing the burden on the environment.

Japanese Patent Laid-Open No. 11-13015 JP 2004-018041 A

  However, a coating composition that does not contain xylene or toluene cannot be sufficiently used as a coating composition for repair because coating workability and drying are not sufficiently obtained.

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and is a vehicle paint composition that does not contain an aromatic compound such as xylene, toluene, ethylbenzene, etc., and has excellent paint workability and drying properties. It is to provide a composition.

  As a result of intensive studies to achieve the above object, the inventor of the present invention uses an ester solvent and at least one hydrocarbon selected from alicyclic hydrocarbons and aliphatic hydrocarbons at a specific ratio. The present inventors have found that it is possible to provide a coating composition for vehicles that is excellent in painting workability and drying properties, and have completed the present invention.

  That is, the vehicle paint composition of the present invention is a vehicle paint composition containing a resin and an organic solvent, wherein the organic solvent is an ester solvent (A), an alicyclic hydrocarbon, and an aliphatic hydrocarbon. And the content of the ester solvent (A) in the organic solvent is 65.0 to 99.0% by mass, and the hydrocarbon is in the organic solvent. Content of (B) is 0.3-25.0 mass%, and content of the aromatic compound which occupies for the said organic solvent is less than 5.0 mass%, It is characterized by the above-mentioned.

  In a preferred example of the vehicle paint composition of the present invention, the organic solvent further contains a ketone solvent (C), and the content of the ketone solvent (C) in the organic solvent is 0.5 to 15.0. % By mass.

  In another preferred embodiment of the vehicle paint composition of the present invention, the ester solvent (A) is ethyl acetate, (iso) butyl acetate, (iso) pentyl acetate, methoxypropyl acetate, ethyl 3-ethoxypropionate. , Butyl glycol acetate, and at least one selected from the group consisting of butyl diglycol acetate.

  In another preferable example of the vehicle paint composition of the present invention, the ketone solvent (C) is at least one selected from the group consisting of methyl pentyl ketone, methyl isopentyl ketone, and methyl ethyl ketone.

  In another preferable example of the vehicle paint composition of the present invention, the resin includes a resin (X) having a weight average molecular weight of 5000 to 60000, and a content of the resin (X) in the entire resin is 80 to 100. % By mass.

  In another preferable example of the vehicle paint composition of the present invention, the resin (X) has an acid value of 3 to 30.

  In another preferable example of the vehicle paint composition of the present invention, the resin (X) is at least one selected from the group consisting of an acrylic resin, a polyester resin, and an alkyd resin.

  The vehicle paint composition of the present invention is preferably a two-component type.

  In another preferred embodiment of the vehicle paint composition of the present invention, a colorant is further contained.

  In another preferred embodiment of the vehicle paint composition of the present invention, a metallic pigment is further included.

  According to the present invention, the content of the ester solvent in the organic solvent is 65.0 to 99.0% by mass, and the content of the alicyclic hydrocarbon and / or the aliphatic hydrocarbon is 0.3 to 25. By adjusting the content to 0% by mass, it is possible to provide a vehicle paint composition having excellent coating workability and drying properties even when the content of the aromatic compound in the organic solvent is less than 5.0% by mass. .

  Hereinafter, the vehicle paint composition of the present invention (hereinafter, also simply referred to as the paint composition of the present invention) will be described in detail. The vehicle paint composition of the present invention is a vehicle paint composition containing a resin and an organic solvent, wherein the organic solvent is selected from an ester solvent (A), an alicyclic hydrocarbon, and an aliphatic hydrocarbon. The content of the ester solvent (A) in the organic solvent is 65.0 to 99.0% by mass, and the hydrocarbon (B ) Is 0.3 to 25.0 mass%, and the content of the aromatic compound in the organic solvent is less than 5.0 mass%. According to the vehicle paint composition of the present invention, by using the ester solvent (A) and the hydrocarbon (B) at a specific ratio, it is possible to provide a vehicle paint composition excellent in coating workability and drying property. Therefore, the content of the aromatic compound in the organic solvent is less than 5.0% by mass, and the effect of reducing the burden on the environment is high.

  In the vehicle paint composition of the present invention, from the viewpoint of reducing the burden on the environment, the content of the aromatic compound in the organic solvent is preferably as low as possible, specifically less than 1.0% by mass. Preferably, it is less than 0.5% by mass, more preferably 0.0% by mass, that is, it is particularly preferable that no aromatic compound is contained. In addition, as an aromatic compound, xylene, toluene, ethylbenzene, etc. are mentioned, for example.

  The organic solvent used in the coating composition of the present invention needs to contain an ester solvent and at least one hydrocarbon selected from alicyclic hydrocarbons and aliphatic hydrocarbons, and further adjust the pot life. Therefore, it is preferable to include a ketone solvent.

  Here, the ester solvent is used to obtain good drying properties and coating workability. The content of the ester solvent in the organic solvent is 65.0 to 99.0% by mass. If the content of the ester solvent is less than 65.0% by mass, the drying property and the coating workability are poor. When it exceeds 99.0% by mass, the appearance of the coating film is deteriorated.

  In the coating composition of the present invention, the content of the ester solvent in the organic solvent is preferably 70.0 to 98.5% by mass. The ester solvent is not particularly limited. For example, methyl acetate, ethyl acetate, (iso) propyl acetate, (iso) butyl acetate, (iso) pentyl acetate, cyclohexyl acetate, 2-ethylbutyl acetate, acetic acid 2-ethylhexyl, sec-hexyl acetate (1-methylpentyl acetate), methyl propionate, ethyl propionate, (iso) propyl propionate, (iso) butyl propionate, (iso) pentyl propionate, methyl butyrate, ethyl butyrate (Iso) propyl butyrate, (iso) butyl butyrate, (iso) propyl butyrate, isobutyl isobutyrate, ethyl 2-hydroxy-2-methylpropionate, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 3-methoxy acetate Butyl, 3-ethoxybutyl acetate, methoxypropyl acetate (PMA), ethyl 3-ethoxypropionate (EEP), butyl glycol acetate, butyl diglycol acetate, etc. Among these, ethyl acetate, (iso) butyl acetate, (iso) pentyl acetate, methoxypropyl acetate, Ethyl 3-ethoxypropionate, butyl glycol acetate, and butyl diglycol acetate are preferred. These ester solvents may be used alone or in combination of two or more.

  In addition, the hydrocarbon used as the organic solvent in the coating composition of the present invention is at least one hydrocarbon selected from alicyclic hydrocarbons and aliphatic hydrocarbons, and has a good coating appearance with a rich feeling. Used to get. In addition, when the coating composition of the present invention containing the hydrocarbon is applied onto a coating film obtained from the metallic coating composition, return unevenness hardly occurs. The content of hydrocarbons (alicyclic hydrocarbons or aliphatic hydrocarbons or a mixture of alicyclic hydrocarbons and aliphatic hydrocarbons) in the organic solvent is 0.3 to 25.0% by mass, and the hydrocarbons If the content is less than 0.3% by mass, a good coating film appearance cannot be obtained. On the other hand, if it exceeds 25.0% by mass, the coating workability is deteriorated.

  In the coating composition of the present invention, the content of hydrocarbons (alicyclic hydrocarbons or aliphatic hydrocarbons or a mixture of alicyclic hydrocarbons and aliphatic hydrocarbons) in the organic solvent is 0.5 to 20.0. It is preferable that it is mass%. The alicyclic hydrocarbon and the aliphatic hydrocarbon are not particularly limited, but as the alicyclic hydrocarbon, a cyclic alkane such as cyclopentane, cyclohexane, and cyclobutane is preferable, and in particular, cyclohexane and alkylcyclohexane. Is preferred. For example, as the alkylcyclohexane, methylcyclohexane, ethylcyclohexane, 1,2-dimethylcyclohexane, 1,3-dimethylcyclohexane, 1,4-dimethylcyclohexane, propylcyclohexane, isopropylcyclohexane, 1-methyl-2-ethylcyclohexane, 1 -Methyl-3-ethylcyclohexane, 1-methyl-4-ethylcyclohexane, 1,2,3-trimethylcyclohexane, 1,2,4-trimethylcyclohexane, 1,3,5-trimethylcyclohexane and the like. Examples of the aliphatic hydrocarbon include n-butane, n-hexane, n-heptane, n-octane, isononane, n-decane, n-dodecane, and other normal paraffin hydrocarbons and isoparaffin hydrocarbons. Such chain saturated hydrocarbons such as isomers of normal paraffin hydrocarbons are preferred, and isoparaffin hydrocarbons are particularly preferred. As for the isoparaffinic hydrocarbon, a commercially available isoparaffinic solvent can be used, and examples thereof include IP solvent 1016, IP solvent 1620, IP solvent 2028 (manufactured by Idemitsu Kosan Co., Ltd.) and the like. In addition, these hydrocarbons may be used individually by 1 type, and may be used in combination of 2 or more type.

  As described above, the organic solvent used in the coating composition of the present invention preferably contains a ketone solvent. The ketone solvent can be used for the purpose of extending the pot life of the coating composition or further improving the coating workability. In the coating composition of the present invention, the content of the ketone solvent in the organic solvent is preferably 0.5 to 15.0% by mass. When the content of the ketone solvent in the organic solvent exceeds 15.0% by mass, the ability to dissolve the resin is too high, and return unevenness easily occurs.

  In the coating composition of the present invention, the content of the ketone solvent in the organic solvent is more preferably 0.5 to 12.0% by mass. The ketone solvent is not particularly limited. For example, acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, 3-pentanone (diethyl ketone), butyl methyl ketone, methyl pentyl ketone (methyl amyl ketone), Examples include monoketones such as methyl isopentyl ketone (methyl isoamyl ketone), dipropyl ketone, diisobutyl ketone, isophorone, cyclohexanone, and methylcyclohexanone, and diketones such as acetonyl acetone and acetyl acetone. Among these, methyl pentyl ketone, methyl Isopentyl ketone and methyl ethyl ketone are preferred. These ketone solvents may be used alone or in combination of two or more.

  In the coating composition of the present invention, the organic solvent may include an ester solvent, an alicyclic hydrocarbon, an aliphatic hydrocarbon, and a solvent other than the ketone solvent (hereinafter also referred to as other organic solvent). The content of other organic solvents in the organic solvent is, for example, 0.1 to 5.0% by mass. Examples of other organic solvents include alcohol solvents such as isopropyl alcohol, isobutyl alcohol and n-butanol, and Solvesso 100. These other organic solvents may be used alone or in combination of two or more.

  In the coating composition of the present invention, the total content of the organic solvent is preferably 35 to 80% by mass.

  As the resin used in the coating composition of the present invention, resins usually used in the coating industry can be used. For example, acrylic resin, epoxy resin, polyester resin, phenol resin, phthalic resin, alkyd resin, fluororesin, urea (urea) ) Resins, polyurethane resins, melamine resins, polyolefin resins, vinyl chloride resins, cellulose resins, and resins modified from these resins, among these, acrylic resins, polyester resins, alkyd resins, and cellulose resins Is preferred. In addition, these resin may be used individually by 1 type, and may be used in combination of 2 or more type.

The resin preferably contains a resin (X) having a weight average molecular weight of 5000 to 60000. It is preferable that the ratio of resin (X) whose weight average molecular weight is 5000-60000 is 80-100 mass% of the whole resin. Since the ester solvent that is the main component of the organic solvent used in the coating composition of the present invention has a very high solvency for a resin having a weight average molecular weight of less than 5000, the weight average molecular weight of the resin used in the coating composition of the present invention. When it is less than 5000, for example, when it is used as a metallic paint composition for vehicles or a clear paint composition for vehicles, it may cause return unevenness. Here, if the weight average molecular weight of the resin is 5000 or more, the occurrence of unevenness of return can be prevented. On the other hand, when the weight average molecular weight of the resin exceeds 60,000, the viscosity of the coating composition increases and the coating workability deteriorates. In the present invention, the weight average molecular weight is a value measured by gel filtration chromatography, and polystyrene is used as the standard substance.
The resin used in the coating composition of the present invention may include a resin having a weight average molecular weight exceeding 60000. In this case, the proportion of the resin having a weight average molecular weight exceeding 60000 is 20% by mass or less of the entire resin. Preferably there is. When the ratio of the resin having a weight average molecular weight exceeding 60,000 exceeds 20% by mass, the viscosity of the coating composition is increased even when the resin having a weight average molecular weight of 5,000 to 60,000 is included, resulting in poor coating workability. There is a fear.

  In addition, as the resin (X), a resin usually used in the paint industry as described above can be used. Among them, from the viewpoint of solubility in organic solvents, coating workability, and durability of the coating film. Acrylic resin, polyester resin, and alkyd resin are preferred.

The resin (X) preferably has an acid value of 3 to 30, and more preferably 5 to 15. When the acid value of the resin (X) is 3 or more, the reaction with the curing agent is efficiently performed, so that the drying property can be further improved. On the other hand, when the acid value of the resin (X) exceeds 30, the pot life tends to be shortened and the resin tends to be colored, which is not preferable.
The acid value of the resin can be measured by a method according to JIS K5601-2-1. Specifically, by quantifying the number of mg of potassium hydroxide required to neutralize 1 g of the resin. Can be measured.

  In the coating composition of the present invention, the resin content is preferably 10 to 35% by mass.

  The vehicle paint composition of the present invention can take various forms depending on the type of compounding agent. For example, a vehicle metallic paint composition, a vehicle enamel paint composition, and a vehicle clear paint composition are used. Is mentioned. When the vehicle paint composition of the present invention is a metallic paint, in addition to the resin and the organic solvent, the vehicle paint composition of the present invention usually further includes a metallic pigment and preferably a pigment dispersant, and the vehicle paint composition of the present invention is an enamel paint. In addition to the above resin and organic solvent, it usually further includes a colorant and preferably a pigment dispersant.

  The metallic pigment is not particularly limited, and may be a known metallic pigment such as aluminum, and may include a pearl pigment such as pearl mica. The colorant is not particularly limited, and known pigments, dyes, and the like can be used. As pigments, azo lake pigments, insoluble azo pigments, monoazo pigments, disazo pigments, condensed azo pigments, chelate azo pigments, azo pigments such as azomethine pigments, phthalocyanine pigments, anthraquinone pigments, perylene pigments, quinacridone pigments, isoindoline pigments, benzimidazolone Other organic pigments such as pigments, thioindigo pigments, dioxazine pigments, quinophthalone pigments, pyrrolopyrrole pigments, and other organic pigments; nitro pigments, nitroso pigments, aniline black, fluorescent pigments; inorganic oxide pigments, hydroxides Pigments, sulfide pigments, ferrocyanide pigments, chromate pigments, carbonate pigments, silicate pigments, phosphate pigments, carbon pigments, inorganic pigments such as metal powders; metal complex pigments Etc. Examples of the dye include oil-soluble dyes such as azos, anthraquinones, indigoids, phthalocyanines, carboniums, quinoneimines, methines, xanthenes, nitros, nitrosos, disperse dyes, acid dyes, reactive dyes, Cationic dyes, direct dyes and the like can be mentioned. In the coating composition of this invention, when a metallic pigment or a coloring agent is included, it is preferable that the content is 1-28 mass%, for example.

  The pigment dispersant is not particularly limited, and a known pigment dispersant can be used. Specific examples include phosphoric pigment dispersants, acrylic pigment dispersants, silicone pigment dispersants, wax pigment dispersants, and the like. In the coating composition of this invention, content of a pigment dispersant is 0.01-5 mass%, for example.

  The coating composition of the present invention includes additives usually used in the coating industry, such as surface conditioners, antifoaming agents, anti-settling agents, fungicides, preservatives, ultraviolet absorbers, or light stabilizers. You may mix | blend suitably. The coating composition of the present invention may be a one-component type or a two-component type. Here, when the coating composition of the present invention is a two-component type, it further contains a curing agent.

  The curing agent is not particularly limited, and a known resin curing agent can be used. Specific examples include aliphatic polyamines, alicyclic polyamines, aromatic polyamines, polyamidoamines, diisocyanates, isocyanurates, and modified products thereof. In the coating composition of this invention, content of a hardening | curing agent is 5-11 mass%, for example.

  The coating composition of the present invention can be prepared by mixing a resin and an organic solvent and various additives appropriately selected as necessary. In addition, when the coating composition of the present invention is a two-component type, a main component containing a resin and an organic solvent and a curing agent component containing a curing agent and an organic solvent are prepared in advance, and these components are mixed immediately before coating. Can be prepared. In addition to the main component and the curing component, an organic solvent can be used as a diluent.

  The paint composition of the present invention is preferably used as a base coat paint or a clear coat paint for vehicles (for example, automobiles, railways, large vehicles, construction machines, etc.), and for various painting purposes such as new installation, repainting, and partial repair. Applicable. Among them, use as a base coat paint or a clear coat paint for automobile repair is more preferable.

  Although the coating method of the coating composition of this invention is not specifically limited, Coating methods, such as brush coating coating, spin coater coating, airless spray coating, air spray coating, electrostatic coating, are possible. Moreover, the drying temperature of the coating composition of this invention is 0 to 120 degreeC, for example, Preferably it is 5 to 100 degreeC. The drying time of the coating composition of the present invention is preferably about 10 hours when the drying temperature is 0 ° C, and preferably 15 to 30 minutes when it is 120 ° C. At the time of painting, an organic solvent may be added and diluted as necessary.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

<Preparation of acrylic resin solutions 1-5>
(Acrylic resin solution 1)
Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, etc., 27 parts by mass of butyl acetate was charged and stirred with heating. After reaching 120 ° C., the following monomer mixture 1 was added dropwise over 3 hours. After the completion of dropping, an additional catalyst solution, which was a mixture of 0.2 parts by mass of 2,2′-azobis-2-methylbutyronitrile and 2 parts by mass of butyl acetate, was added dropwise over 1 hour while maintaining 120 ° C. . The solution after dropping was further stirred at 120 ° C. for 1 hour and then cooled. The cooled solution was diluted by adding 12 parts by mass of butyl acetate to obtain an acrylic resin solution 1 having a solid content concentration of 61.1% by mass. The acrylic resin in the obtained acrylic resin solution 1 had a weight average molecular weight (Mw) of 9,800 and an acid value of 10.5 mgKOH / g.
Monomer mixture 1: 3 parts by mass of styrene, 14 parts by mass of methyl methacrylate, 22 parts by mass of n-butyl methacrylate, 9 parts by mass of t-butyl methacrylate, 1 part by mass of methacrylic acid, 7 parts by mass of 2-hydroxyethyl methacrylate, butanediol mono 5 parts by mass of acrylate, and 3 parts by mass of 2,2′-azobis-2-methylbutyronitrile as a polymerization initiator

(Acrylic resin solution 2)
Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser and the like, 27 parts by mass of butyl acetate was charged and stirred with heating. After reaching 120 ° C., the following monomer mixture 2 was added dropwise over 3 hours. After the completion of dropping, an additional catalyst solution, which was a mixture of 0.2 parts by mass of 2,2′-azobis-2-methylbutyronitrile and 2 parts by mass of butyl acetate, was added dropwise over 1 hour while maintaining 120 ° C. . The solution after dropping was further stirred at 120 ° C. for 1 hour and then cooled. The cooled solution was diluted by adding 12 parts by mass of butyl acetate to obtain an acrylic resin solution 2 having a solid content concentration of 61.2% by mass. The acrylic resin in the obtained acrylic resin solution 2 had a weight average molecular weight (Mw) of 5,000 and an acid value of 10.1 mgKOH / g.
Monomer mixture 2: 3 parts by weight of styrene, 14 parts by weight of methyl methacrylate, 22 parts by weight of n-butyl methacrylate, 9 parts by weight of t-butyl methacrylate, 1 part by weight of methacrylic acid, 7 parts by weight of 2-hydroxyethyl methacrylate, butanediol mono 5 parts by mass of acrylate, and 4 parts by mass of 2,2′-azobis-2-methylbutyronitrile as a polymerization initiator

(Acrylic resin solution 3)
Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and the like, 27 parts by mass of butyl acetate was charged and stirred with heating. After reaching 100 ° C., the following monomer mixture 3 was added dropwise over 3 hours. After completion of the dropwise addition, an additional catalyst solution, which was a mixture of 0.2 parts by mass of 2,2′-azobis-2-methylbutyronitrile and 2 parts by mass of butyl acetate, was added dropwise over 1 hour while maintaining 100 ° C. . The solution after dropping was further stirred at 100 ° C. for 1 hour and then cooled. The cooled solution was diluted by adding 12 parts by mass of butyl acetate to obtain an acrylic resin solution 3 having a solid content concentration of 60.0% by mass. The acrylic resin in the resulting acrylic resin solution 3 had a weight average molecular weight (Mw) of 58,000 and an acid value of 10.6 mgKOH / g.
Monomer mixture 3: Styrene 3 parts by mass, methyl methacrylate 14 parts by mass, n-butyl methacrylate 22 parts by mass, t-butyl methacrylate 9 parts by mass, methacrylic acid 1 part by mass, 2-hydroxyethyl methacrylate 7 parts by mass, butanediol mono 5 parts by mass of acrylate and 0.3 parts by mass of 2,2′-azobis-2-methylbutyronitrile as a polymerization initiator

(Acrylic resin solution 4)
Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser and the like, 27 parts by mass of butyl acetate was charged and stirred with heating. After reaching 120 ° C., the following monomer mixture 4 was added dropwise over 3 hours. After the completion of dropping, an additional catalyst solution, which was a mixture of 0.2 parts by mass of 2,2′-azobis-2-methylbutyronitrile and 2 parts by mass of butyl acetate, was added dropwise over 1 hour while maintaining 120 ° C. . The solution after dropping was further stirred at 100 ° C. for 1 hour and then cooled. The cooled solution was diluted by adding 12 parts by mass of butyl acetate to obtain an acrylic resin solution 4 having a solid content concentration of 60.0% by mass. The acrylic resin in the resulting acrylic resin solution 4 had a weight average molecular weight (Mw) of 10,000 and an acid value of 8.2 mgKOH / g.
Monomer mixture 4: 3 parts by mass of styrene, 14 parts by mass of methyl methacrylate, 22 parts by mass of n-butyl methacrylate, 9 parts by mass of t-butyl methacrylate, 0.8 parts by mass of methacrylic acid, 7 parts by mass of 2-hydroxyethyl methacrylate, butane 5 parts by mass of diol monoacrylate and 3 parts by mass of 2,2′-azobis-2-methylbutyronitrile as a polymerization initiator

(Acrylic resin solution 5)
Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, etc., 27 parts by mass of butyl acetate was charged and stirred with heating. After reaching 120 ° C., the following monomer mixture 5 was added dropwise over 3 hours. After the completion of dropping, an additional catalyst solution, which was a mixture of 0.2 parts by mass of 2,2′-azobis-2-methylbutyronitrile and 2 parts by mass of butyl acetate, was added dropwise over 1 hour while maintaining 120 ° C. . The solution after dropping was further stirred at 120 ° C. for 1 hour and then cooled. The cooled solution was diluted by adding 12 parts by mass of butyl acetate to obtain an acrylic resin solution 5 having a solid content concentration of 61.0% by mass. The acrylic resin in the resulting acrylic resin solution 5 had a weight average molecular weight (Mw) of 10,000 and an acid value of 12.2 mgKOH / g.
Monomer mixture 5: Styrene 3 parts by mass, methyl methacrylate 14 parts by mass, n-butyl methacrylate 22 parts by mass, t-butyl methacrylate 9 parts by mass, methacrylic acid 1.2 parts by mass, 2-hydroxyethyl methacrylate 7 parts by mass, butane 5 parts by mass of diol monoacrylate and 3 parts by mass of 2,2′-azobis-2-methylbutyronitrile as a polymerization initiator

<Preparation of enamel coating composition: Examples 1 to 17, Comparative Example 4>
About the main ingredient component, the main ingredient component was prepared by mixing the raw materials shown in Tables 1 to 3 and 7 and dispersing the colorant by a known method. Moreover, about the hardening | curing agent component and the diluent component, the raw material shown in Tables 1-3 and 7 was mixed and prepared.
Next, the enamel coating composition was prepared by mixing the main component and the curing agent component immediately before use. And the diluent component was added to this enamel coating composition, and the viscosity was adjusted so as to be suitable for coating.

<Preparation of metallic coating composition: Examples 18 to 27, Comparative Example 5>
About the main ingredient component, the raw materials shown in Tables 4 and 7 were mixed, and the main ingredient component was prepared by dispersing the metallic pigment by a known method. Moreover, about the hardening | curing agent component and the diluent component, the raw material shown in Table 4 and 7 was mixed and prepared.
Next, the main component and the curing agent component were mixed immediately before use to prepare a metallic coating composition. And the diluent component was added to this metallic coating composition, and the viscosity adjustment was performed so that it might be suitable for coating.

<Preparation of Clear Coating Composition: Examples 28 to 37, Comparative Examples 1 to 3 and 6>
The raw materials shown in Tables 5 to 7 were mixed to prepare a main component, a curing agent component, and a diluent component, respectively. Next, a main coating component and a curing agent component were mixed immediately before use to prepare a clear coating composition. And the diluent component was added to this clear coating composition, and the viscosity adjustment was performed so that it might be suitable for coating.

Details of the raw materials indicated by trade names in the table will be described below.
・ Colorant CR-95 (Titanium oxide, manufactured by Ishihara Sangyo)
Raven 5000 Ultra II (carbon black, Colombian)
Chromofine blue 5191D (phthalocyanine pigment, manufactured by Dainichi Seika)
・ Organic solvent IP solvent 1620 (isoparaffinic solvent, manufactured by Idemitsu Kosan Co., Ltd.)
・ Surface conditioner BYK333 (silicone surface conditioner, manufactured by Big Chemie Japan)
・ Hardener Sumidur N3300 (Isocyanurate modified from hexamethylene diisocyanate, manufactured by Sumika Bayer Urethane)
Duranate TPA100 (isocyanurate-modified hexamethylene diisocyanate, manufactured by Asahi Kasei Chemicals)
Metallic pigment 7640NS (aluminum pigment dispersion, solid content 65% by weight, dispersion solvent: mineral spirit and aromatic hydrocarbon, manufactured by Toyo Aluminum)
-Cellulose resin H1 / 2 (about 70% by mass of nitrocellulose, about 30% by mass of isopropyl alcohol, manufactured by Taihei Chemical)

<Evaluation>
1. Preparation of base material A cation electrodeposition coating film (film thickness 20 μm) and an acrylic resin surfacer layer (20 to 30 μm) are laminated in this order on the surface of a zinc-based plated steel sheet used as an anti-rust steel sheet for automobiles. A material was prepared.

2. The coating composition (Examples 1 to 37, Comparative Examples 1 to 6) is air-coated on the base material prepared in “1. Preparation of base material” so that the dry film thickness is 40 to 50 μm. After coating with a spray, the coating film was dried at 60 ° C. for 30 minutes, and the coating workability was evaluated according to the following evaluation criteria.
◯: The paint spread evenly on the substrate immediately after spraying, and the coating workability was good.
X: The paint immediately after spraying did not sufficiently wet and spread on the substrate, and the coating workability was poor.

3. On the base material produced in the drying property “1. Production of base material”, the coating compositions (Examples 1 to 37, Comparative Examples 1 to 6) are air sprayed so that the dry film thickness is 40 to 50 μm. The coating film was dried at a temperature of 60 ° C. for 10 minutes, and the drying property was evaluated according to the following evaluation criteria.
○: When the coating film was lightly touched with the fingertip, the paint did not adhere to the fingertip.
X: When the coating film was lightly touched with a fingertip, the paint adhered to the fingertip.

4). The coating composition (Examples 1 to 37, Comparative Examples 1 to 6) is air-coated on the base material prepared in “1. Preparation of base material” on the coating film appearance so that the dry film thickness becomes 40 to 50 μm. The coating was applied by spraying, and the coating film was dried at a temperature of 60 ° C. for 1 hour to prepare a coated plate. The coating film appearance of the coated plate was evaluated according to the following evaluation criteria.
○: A smooth coating film was obtained.
X: A smooth coating film was not obtained.

5. Pot Life First, the coating compositions (Examples 1 to 37, Comparative Examples 1 to 6) were not used for coating immediately after preparation but were allowed to stand at 40 ° C. for 2 hours. Next, the coating compositions (Examples 1 to 37, Comparative Examples 1 to 6) are air-treated on the base material prepared in “1. Preparation of base material” so that the dry film thickness becomes 40 to 50 μm. The coating was applied by spraying, and the coating film was dried at a temperature of 60 ° C. for 1 hour to prepare a coated plate. Further, a coated plate was produced in the same manner except that the condition of leaving was changed to 40 ° C. × 2 hours 30 minutes. Pot life was evaluated according to the following evaluation criteria.
A: Even when the condition for standing was 40 ° C. × 2 hours 30 minutes, the paint spread evenly on the substrate immediately after spraying, the coating workability was good, and a smooth coating film was obtained.
◯: When the condition for standing was 40 ° C. × 2 hours, the paint spread evenly on the substrate immediately after spraying, the coating workability was good, and a smooth coating film was obtained. However, when the condition is left at 40 ° C. × 2 hours 30 minutes, the viscosity of the paint increases, and even if the spray gun is clogged or painted, it is applied in a rough state and a smooth coating film is obtained. I couldn't.
X: Under either of the standing conditions, the viscosity of the paint was high and the spray gun was clogged at the time of painting or even if it could be painted, it was painted in a rough state and a smooth coating film could not be obtained.

6). Return unevenness (Example 38)
On the base material prepared in “1. Preparation of base material”, the metallic paint composition of Example 18 was applied by air spray so that the dry film thickness was 20 to 30 μm, and the coating film was heated to 60 ° C. The coating plate provided with the metallic layer was produced by drying at ° C for 15 minutes. Next, the coated plate was cooled to room temperature (20 to 25 ° C.), and the clear coating composition of Example 28 was applied onto the metallic layer by air spray so that the dry film thickness was 30 to 40 μm. The film was dried at a temperature of 60 ° C. for 15 minutes to produce a coated plate having a clear layer on the metallic layer. Return unevenness was evaluated according to the following evaluation criteria.
◯: A good metallic appearance was exhibited, and no return unevenness occurred.
X: Remarkable unevenness was seen in the metallic appearance, and return unevenness occurred.
(Examples 39 to 56)
A coated plate was produced by the same coating method as in Example 38 except that the metallic paint composition and the clear paint composition were changed to the combinations shown in Table 8, and the return unevenness was evaluated according to the same evaluation criteria as in Example 38.

Claims (3)

A vehicle paint composition comprising a resin and an organic solvent, wherein the resin comprises a resin (X) having a weight average molecular weight of 5000 to 60000, and the content of the resin (X) in the entire resin is 86. 1 to 100% by mass, the resin (X) is an acrylic resin having an acid value of 3 to 30, and the organic solvent is an ester solvent (A), an alicyclic hydrocarbon and an aliphatic hydrocarbon. It contains at least one selected hydrocarbon (B) and further a ketone solvent (C), and the content of the ester solvent (A) in the organic solvent is 65.0 to 99.0% by mass. The content of the hydrocarbon (B) in the organic solvent is 0.3 to 25.0 mass%, and the content of the ketone solvent (C) in the organic solvent is 0.5 to 15.0 mass%. %, And the ester solvent (A) is ethyl acetate, vinegar Acid (iso) butyl, acetic acid (iso) pentyl, methoxypropyl acetate, ethyl 3-ethoxypropionate, butyl glycol acetate, and butyl diglycol acetate, and the ketone solvent ( C) is at least one selected from the group consisting of methylpentyl ketone, methyl isopentyl ketone, and methyl ethyl ketone, and the content of the aromatic compound in the organic solvent is less than 5.0% by mass. A two-pack type coating composition for vehicles. The vehicle paint composition according to claim 1, further comprising a colorant. Furthermore, the vehicle composition for coating according to claim 1 or 2, characterized in that it comprises a metallic pigment.