JP5841412B2 - COATING BODY, METAL COATING COMPOSITION AND METHOD OF COATING THE SAME - Google Patents

Description

  The present invention relates to a coated body obtained by coating a chrome plating of a resin material on a metal surface, in particular, an automobile exterior decoration, mainly a radiator grill, an emblem, and the like. The present invention relates to a coating composition for coating and a coating method thereof.

  It is known that a material obtained by applying chrome plating to a resin material is coated with a transparent color clear or an exterior color that partially matches the body color in order to improve the design.

  These chromium platings have a hard metal chromium surface and poor adhesion to the coating film, and the reaction between acrylic and epoxy silane compounds with amino groups, rather than acrylic-urethane paints, which are often used in plastic plastics. It is known that an acrylic-silicone resin coating using a siloxane bond obtained in (1) is advantageous (for example, see Patent Document 1).

  The above acrylic-silicone resin paint has a brittle property on the other hand, but it has a brittle property, and it is easy to cause scratches due to pebbles colliding (chipping) that the car jumps while driving. The agent induces corrosion of the plating base and causes the coating film to peel off.

  On the other hand, the viscosity of a specific range obtained by reacting a hydroxyl group-containing resin (A) having a specific hydroxyl value and a specific average molecular weight, a polyisocyanate compound (B), and a diol having 2 to 10 carbon atoms with a carbonylating agent. In addition, it has been proposed to use a coating composition containing a polycarbonate diol compound (C) having a specific number average molecular weight in an automobile (see, for example, Patent Document 2).

  With the above polycarbonate diol-containing paint, the hardness of the coating film can be obtained in the same way as with the acrylic-silicone paint, but it is difficult to suppress the occurrence of scratches caused by the collision of the pebbles that the automobile jumps during driving (chipping). The snow melting agent induced corrosion of the plating base from the scratches caused by chipping, which was a factor in peeling the coating film.

JP-A-8-71496 Special table 2009-530425 gazette

  In order to suppress the brittleness of acrylic-silicon paints, techniques such as using acrylic-urethane resin in combination with lowering the hardness to suppress chipping have been tried. It was difficult to improve the chipping resistance while maintaining the above.

  An object of the present invention is to solve the above-mentioned problems, that is, a coated body having good chipping resistance while maintaining the coating film hardness, and excellent in weather resistance and adhesion, its coating method, and metal coating composition Is to provide things.

According to the present invention, there is provided a coated body having at least two coating layers of a coating on a metal surface,
The coating in the lowermost layer in the coating layer is modified with an acrylic resin having an amino group and a hydroxyl group and polycarbonate diol, and has a glass transition temperature (Tg) of −75 ° C. or higher and −60 ° C. or lower, and a number average molecular weight. (Mw) containing a polyester resin, a silicon compound and a polyisocyanate compound having a molecular weight of 500 g / mol or more and 2500 g / mol or less ,
A coated body is provided in which the mass ratio of the acrylic resin and the polyester resin is 6: 4 to 9: 1 in terms of solid content.

Further, according to the present invention, in the method for producing a coated body in which at least two coating layers of paint are formed on the metal surface,
Forming a metal layer on the surface of the substrate;
The lowermost layer of the coating layer on the metal is an acrylic resin having an amino group and a hydroxyl group, a glass transition temperature (Tg) of −75 ° C. or more and −60 ° C. or less, and a number average molecular weight (Mw) of 500 g. Containing a polycarbonate diol-modified polyester resin, a silicon compound and a polyisocyanate compound that are not less than / mol and not more than 2500 g / mol , and the mass ratio of the acrylic resin to the polyester resin is 6: 4 to 9: 1 in terms of solid content There is provided a method for producing a coated body comprising a step of applying a coating composition.

Further, according to the present invention, there is provided a metal coating composition for forming at least two coating layers of a coating on a metal surface,
The coating in the lowermost layer in the coating layer is modified with an acrylic resin having an amino group and a hydroxyl group and polycarbonate diol, and has a glass transition temperature (Tg) of −75 ° C. or higher and −60 ° C. or lower, and a number average molecular weight. (Mw) containing a polyester resin, a silicon compound and a polyisocyanate compound having a molecular weight of 500 g / mol or more and 2500 g / mol or less ,
A metal coating composition is provided in which the mass ratio of the acrylic resin to the polyester resin is 6: 4 to 9: 1 in terms of solid content.

  The coated body, the coating method thereof, and the coating composition for metal according to the present invention can provide a coated body having good chipping resistance while maintaining the coating film hardness and excellent in weather resistance and adhesion. It was.

  Hereinafter, embodiments of the present invention will be described in detail.

  The acrylic resin containing a hydroxyl group and an amino group used in the present invention is composed of one or more monomers having a hydroxyl group and / or an amino group, and other ethylenic monomers that can be polymerized with these monomers. It is obtained by polymerizing one or more monomers having a saturated bond.

  Examples of hydroxyl-containing acrylic monomers include 2-alkylethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate and other hydroxyalkyl esters of 2 to 24 carbon atoms and lactones such as hydroxybutyl (meth) acrylate. Examples thereof include modified hydroxyalkyl esters.

  Examples of the amino group-containing acrylic monomer include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and N, N-di. -T-butylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, etc. are mentioned.

  Examples of other monomers that can be polymerized with the above monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, and tert-butyl. C1-C24 alkyl or cycloalkyl esters such as (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate; glycidyl (meth) Acrylate; Monomer having alkoxysilyl group such as γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyldiethoxysilane (Meth) acrylic acid, itaconic acid, carboxylic acids having an ethylenic unsaturated bond, such as crotonic acid; styrene, vinyl toluene, styrene based monomers such as α- methylstyrene; and (meth) acrylonitrile.

  The hydroxyl group-containing acrylic resin used in the present invention preferably has a hydroxyl value of 5 to 200 mgKOH / g, and a number average molecular weight (Mw) of preferably 1,000 to 20,000, more preferably 2,000 to 15. 000 is suitable. When a hydroxyl group-containing acrylic resin having a hydroxyl value of less than 5 mgKOH / g is used, the weather resistance and solvent resistance tend to decrease, and when a hydroxyl group-containing acrylic resin having a hydroxyl value exceeding 200 mgKOH / g is used. Have a tendency to decrease acid resistance and moisture resistance. In addition, when a hydroxyl group-containing acrylic resin having a number average molecular weight of less than 1,000 is used, low-temperature curability and solvent resistance tend to decrease, and a hydroxyl group-containing acrylic having a number average molecular weight exceeding 20,000. When resin is used, the smoothness of the coating surface and the fineness during spray coating tend to decrease.

  In the present invention, the content of the acrylic resin containing a hydroxyl group and an amino group used as the lowermost layer coating is preferably 50 to 90% by mass, more preferably 60 to 70% by mass in the coating resin. If the amount is less than 50% by mass, the tackiness increases and affects the upper layer coating film, and the curing rate tends to decrease. If the amount exceeds 90% by mass, the chipping resistance decreases and the target performance is difficult to obtain.

  The content of the acrylic resin used as the outermost layer coating material in the present invention is preferably 40 to 90% by mass, more preferably 65 to 75% by mass in the coating resin. If it is less than 40% by mass, the coating film hardness tends to decrease, and if it exceeds 90% by mass, the chipping resistance tends to deteriorate.

  The polyester resin used in the present invention can be produced by a known esterification reaction using a combination of a polyol component, which is a normal raw material constituting the polyester resin, and a polyvalent carboxylic acid or an ester-forming derivative thereof. There is no restriction | limiting in particular about the manufacturing method of a polyester resin, For example, methods, such as a melt condensation method, an azeotropic condensation method, or these combined use, can be used.

  Examples of the polyol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, and 2-butyl-2-ethyl-1,3-propane. Diol, 1,4-butanediol, neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2 -Methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, diethyleneglycol , Aliphatic diols such as triethylene glycol, alicyclic diols such as cyclohexanedimethanol and cyclohexanediol, trimethylolethane, trimethylolpropane, hexitols, pentitols, glycerin, pentaerythritol, and tetramethylolpropane And trivalent or higher alcohols. These polyol components may be used alone or in combination of two or more.

  Examples of the polyvalent carboxylic acid or its ester-forming derivative include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, 2-methylsuccinic acid 2-methyladipic acid, 3-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,8-dimethyldecanedioic acid, 3,7-dimethyldecanedioic acid, hydrogenated dimer acid, Aliphatic dicarboxylic acids such as dimer acid, aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2- Cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1 4-dicarboxylic methylenecyclohexane, alicyclic dicarboxylic acids such as nadic acid, methyl nadic acid, polycarboxylic acids such as trimellitic acid, trimesic acid, castor oil fatty acid trimer, and other polycarboxylic acids such as these Acid anhydrides, halides of polyvalent carboxylic acids, halides such as bromides, methyl esters of the polyvalent carboxylic acids, ethyl esters, propyl esters, isopropyl esters, butyl esters, isobutyl esters, amyl esters and lower esters, Examples include lactones such as γ-caprolactone, δ-caprolactone, ε-caprolactone, dimethyl-ε-caprolactone, δ-valerolactone, γ-valerolactone, and γ-butyrolactone. These 1 type and several types can be mixed and used in arbitrary ratios.

  Among them, it is more preferable to use polycarbonate diol-modified polyester. The polycarbonate diol-modified polyester can be produced by a known method, for example, 200 to 250 ° C. while stirring the polycarbonate diol with one or more polyhydric alcohol and / or polycarboxylic acid under nitrogen gas reflux. And obtained by reacting for 1 to 20 hours.

  Polycarbonate diol is usually a compound obtained by polycondensation reaction of a known diol and a carbonylating agent. Specific examples include, for example, “Placcel CD205PL”, “Plaxel CD210”, “Plaxel CD220”, “Plaxel CD220PL” manufactured by Daicel Chemical Industries, Ltd., “ETERRNACOLL UH-50”, “ETERACOLLOL UH” manufactured by Ube Industries, Ltd. -100 "," ETERARNACOLL UH-200 "," ETERARNACOLL UH-300 "," ETERARNACOLL UHC50-200 "," ETERARNACOLL UHC50-100 "," ETERARNACOLL UC-100 ", and" ETERARNACOLL UM-90 ". .

  In the present invention, the content of the polyester resin used as the lowermost layer coating is preferably 30 to 40% by mass in the coating resin, but more preferably 30 to 35% by mass. If it is less than 30% by mass, the chipping resistance tends to be lowered, and if it exceeds 40% by mass, the coating tends to be hardened.

  The content of the polyester resin used as the outermost layer coating material in the present invention is preferably 5 to 30% by mass in the coating resin, and more preferably 10 to 15% by mass. If it is less than 5% by mass, scratches on the coating film are easily noticeable, and if it exceeds 30% by mass, the hardness of the coating film tends to decrease.

  The glass transition temperature (Tg) of the polycarbonate diol-modified polyester is preferably −75 ° C. or higher and −60 ° C. or lower, and more preferably −75 ° C. or higher and −65 ° C. or lower. When the glass transition temperature (Tg) of the polycarbonate diol-modified polyester is less than −75 ° C., curing of the coating film becomes dull, and when it exceeds −60 ° C., chipping resistance tends to deteriorate. The number average molecular weight (Mw) of the polycarbonate diol-modified polyester is preferably 500 g / mol to 2500 g / mol, and more preferably 800 g / mol to 1200 g / mol. When the number average molecular weight (Mw) of the polycarbonate diol-modified polyester is less than 500 g / mol, the film formation tends to be poor, and when it exceeds 2500 g / mol, the appearance tends to deteriorate.

  The mass ratio of the acrylic resin and the polyester resin used in the present invention is essentially 6: 4 to 9: 1 in terms of solid content, but more preferably 6: 4 to 7: 3. When the acrylic ratio is less than 6, the coating film hardness decreases, and when it exceeds 9, the chipping resistance deteriorates.

  The silicon compound used in the present invention is preferably a silicon compound having at least one epoxy group and hydrolyzable alkoxysilane group in one molecule. For example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3,4-epoxycyclohexylmethyltrimethoxysilane, 3,4-epoxycyclohexylethyl Examples include trimethoxysilane and condensates thereof. The silicon compound may be a single compound or a mixture of two or more.

  The silicon compound is preferably adjusted to the same amount for both the lowermost layer coating and the outermost layer coating based on the equivalent relationship between the amino group and hydroxyl group in the coating composition and the epoxy group in the silicon compound. When the amino group is excessive, sufficient reaction cannot be obtained and adhesion is reduced. When the epoxy group is excessive, the contact resistance is decreased.

  Examples of the polyisocyanate compound used in the present invention include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1 , 3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate and other aliphatic diisocyanates, 1,3-cyclopentane diisocyanate, 1, 4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4′-methyl Cyclohexane such as bis (cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,4-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane Alkylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate or Mixtures thereof, aromatic diisocyanates such as 4,4′-toluidine diisocyanate, dianisidine diisocyanate, 4,4′-diphenyl ether diisocyanate, 1, -Or fragrance such as 1,4-xylylene diisocyanate or a mixture thereof, ω, ω'-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-bis (α, α-dimethylisocyanatomethyl) benzene Aliphatic diisocyanates, triphenylmethane-4,4 ′, 4 ″ -triisocyanate, 1,3,5-triisocyanatebenzene, 2,4,6-triisocyanatotoluene triisocyanate, 4,4′-diphenyldimethyl Examples include tetraisocyanates such as methane-2,2 ′, 5,5′-tetraisocyanate, and polymerized polyisocyanates such as dimers and trimers of tolylene diisocyanate and polyphenylpolymethylene polyisocyanate. These can be used alone or as a mixture of two or more. It is.

  The polyisocyanate compound generally has a ratio of isocyanate groups to hydroxyl groups of 0.8 to 1.2 hydroxyl groups per isocyanate group, particularly 0.9 to 1 for both the lowermost layer coating and the outermost layer coating. It is more preferable to blend so that the isocyanate group becomes excessive. If it is less than 0.8, the adhesion between the layers tends to decrease, and if it exceeds 1.2, the coating film hardness tends to decrease.

  In the present invention, a pigment can also be added. Examples of the pigment used include monoazo, disazo, lake azo, β naphthol, naphthol AS, benzimidazolone, condensed disazo, azo metal complex pigment, phthalocyanine, quinacridone, perylene, and perinone. Thioindigo, anthrone, anthraquinone, flavantron, indanthrone, isoviolanthrone, pyranthrone, dioxazine, quinophthalone, isoindolinone, isoindoline and diketopyrrolopyrrole pigments, carbon black, titanium dioxide, Zinc sulfide, iron oxide, chromium oxide, ultramarine, nickel antimony titanium oxide, chromium antimony titanium oxide, cobalt oxide, mixed oxide of cobalt and aluminum, bismuth vanadate, and mixed pigments It is. The above-mentioned pigments can be used alone or in combination of two or more.

  The solvent used in the present invention is not particularly limited as long as it is generally used for paints. For example, aromatic hydrocarbons such as toluene, xylene, Solvesso 100, Solvesso 150, ethyl acetate, acetic acid Examples include esters such as butyl, ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone, aliphatic solvents such as alcohols, glycols, acetates, and mineral spirits, and water. These are appropriately selected in consideration of solubility, evaporation rate and safety. The solvent mentioned above can be used individually by 1 type or in mixture of 2 or more types.

  Other additives are not particularly limited, for example, extender pigments such as barium sulfate and calcium carbonate, matting agents such as silica and alumina, antifoaming agents, leveling agents, anti-sagging agents, surface conditioners, viscosity modifiers And conventional additives such as an agent, a dispersant, an ultraviolet absorber, a polymer stabilizer, and a wax.

  Further, in the present invention, by applying a clear coating on the outermost layer of the coating layer, there is an effect of suppressing the influence of ultraviolet rays and maintaining the color tone of the colored lower layer, so that an improvement in weather resistance can be expected.

  The resin of the clear coating used is preferably a two-pack type clear obtained by a reaction between a polyol and a polyisocyanate having good weather resistance such as acrylic, polyester, silicon-modified acrylic and fluorine-modified acrylic. In order to improve the chipping resistance, the clear coating resin preferably contains 5 to 15% by mass of polycarbonate diol-modified polyester, more preferably 7 to 10% by mass.

  The solvent used for the clear coating is preferably a weak solvent that hardly affects the underlying coating film, such as butyl acetate, methoxypropyl acetate, methoxybutyl acetate, methyl isobutyl ketone, diisobutyl ketone, and cyclohexane. The solvent content of the clear coating is preferably 45 to 55% by mass, more preferably 49 to 53% by mass.

  Examples of the metal used in the present invention include various metal plates and resin substrates coated with metal such as plating. As various metal plates, for example, cold rolled steel plate, hot rolled steel plate, galvanized steel plate, alloy galvanized steel plate, zinc-iron alloy plated steel plate, zinc-aluminum alloy plated steel plate, aluminum plated steel plate, chrome plated steel plate, tin plated steel plate Examples of such steel plates include aluminum plates, aluminum plates, stainless steel plates, and titanium plates.

  Conventionally known plating methods can be used for resin-coated resin substrates such as plating, for example, dry plating such as vacuum plating and chemical vapor plating, electroplating, chemical plating and hot dipping. Wet plating such as

  Among these, from the viewpoint of weight reduction and workability of the base material, a method of applying chromium plating to the resin parts by electroplating is preferable. As a method of performing chromium plating by electroplating on resin parts, for example, after forming a base plating layer using chromic acid etching and chemical nickel on a molded product obtained by injection molding of ABS resin, by electroplating, A method of forming a chromium film on the outermost surface of the molded article by plating with copper, nickel, chromium (hexavalent chromium bath or trivalent chromium bath), and the like. In addition, since each plating film thickness and the plating structure under chrome plating differ with product specifications, they are not fixed.

  A method of applying a chipping-resistant coating material applied on the resin chrome plating according to the embodiment of the present invention will be described.

  The method of painting the chipping-resistant paint is to coat the lowermost paint of acrylic-silicone resin system containing polyester resin in the paint resin and urethane curing together on the chrome-plated resin parts. The outermost layer is preferably coated with an outermost layer paint of acrylic and polyester-urethane resin.

  Further, this lowermost layer coating can be colored with the above-mentioned pigments, and is preferably applied in a film thickness range of 10 μm to 30 μm in order to impart design properties and at the same time maintain impact absorption performance. Subsequent coating of the outermost layer coating is preferably performed in a film thickness range of 20 μm to 40 μm in order to have functions of mitigating impact on the lowermost layer coating, concealing chipping scratches, and improving weather resistance by absorbing ultraviolet rays. .

  When the film thickness of the lowermost layer paint is 10 μm or more and the film thickness of the outermost layer paint is 20 μm or more, the reduction of chipping scratches is increased, and improvement of chipping resistance can be expected. The chipping resistance of the coating film increases as the film thickness increases, and the influence of the film thickness of the lowermost layer paint is greater than the film thickness of the outermost layer paint.

  The coating composition for metal used in the present invention can be prepared by using commonly used machines such as a roller mill, a paint shaker, a pot mill, a disper, and a sand grind mill.

  The method for applying the metal coating composition is not particularly limited. For example, it is generally used such as dipping, brush, roller, roll coater, air spray, airless spray, curtain flow coater, roller curtain coater, and die coater. The coating method etc. which can be mentioned can be mentioned. These are appropriately selected according to the purpose of use of the substrate.

  The chrome-plated surface used in the present invention is preferably subjected to a known plating treatment on a plastic substrate such as acrylonitrile butadiene styrene (ABS) or polycarbonate, and the coating surface state is preferably kept clean, and the paint performance is improved. It can be fully demonstrated.

  Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, “parts” and “%” are based on mass unless otherwise specified.

(Synthesis Example 1)
A clean container refluxed with nitrogen gas is charged with 27 parts of trimethylolpropane, 212 parts of hexanediol, 292 parts of adipic acid, 24 parts of benzoic acid and 500 parts of polycarbonate diol (trade name: Plaxel CD205PL, manufactured by Daicel) and stirred. The temperature was raised to 240 ° C. and kept for 10 hours, followed by cooling. The product thus obtained is designated as polyester resin (A). The polycarbonate diol-modified polyester resin (A) had a hydroxyl value of 112, a number average molecular weight (Mw) of 1100 g / mol, and a glass transition temperature (Tg) of −69 ° C.

(Synthesis Example 2)
A clean container refluxed with nitrogen gas was charged with 27 parts of trimethylolpropane, 224 parts of hexanediol, 584 parts of adipic acid, 24 parts of benzoic acid and 1500 parts of polycarbonate diol (trade name: Plaxel CD205PL, manufactured by Daicel) and stirred. The temperature was raised to 240 ° C. and kept for 10 hours, followed by cooling. The product thus obtained is designated as polyester resin (D). The polycarbonate diol-modified polyester resin (D) had a hydroxyl value of 56, a number average molecular weight (Mw) of 2000 g / mol, and a glass transition temperature (Tg) of −65 ° C.

(Method of forming chrome plating on ABS base material)
After forming a base plating layer using chromic acid etching and chemical nickel on the molded product obtained by injection molding of ABS resin, copper 15 μm and nickel 15 μm by electroplating, 0.2 μm in order of hexavalent chromium bath Plating was performed to form a chromium film on the outermost surface of the molded product.

(Example 1)
Example 1 has the components shown in Table 1 below, and the main component of the undercoat coating used as the lowermost layer is an acrylic resin solution (A) having a hydroxyl group (trade name: ACRYDIC WYU188, manufactured by DIC Corporation). , 30 parts of solid content (NV) = 55%, Acrylic resin solution having amino group (B) (trade name: ACRYDIC TY924, manufactured by DIC, NV = 50%), 33 parts, polyester resin (B) (becco) Light WHF363, manufactured by DIC, NV = 70%) 6 parts and toluene (TL) / butyl acetate (BA) = 1/1 mixed solution 31 parts as a solvent were kneaded with a disper for 30 minutes to obtain a main agent. . Further, as a curing agent, disperse 5 parts of 3-glycidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Silicon Co., Ltd.) and 6 parts of polyisocyanate (A) (trade name: Barnock DN980, manufactured by DIC). Kneaded for 30 minutes to obtain a curing agent.

  Next, the main agent and curing agent of the undercoat paint are kneaded with a disper for 30 minutes, and applied to the object ABS-chrome plating material after chrome plating by air spray so that the film thickness becomes 10 to 20 μm. A lower layer was formed.

  As a top coat on the lowermost layer obtained, acrylic resin (C) (trade name: Desmophen A870, manufactured by Sumika Bayer, NV = 70%) 26 parts, polyester resin (C) (trade name: Desmophen 670BA, 29 parts by Sumika Bayer, NV = 80%, 5 parts polyester resin (A), 2 parts UV absorber (trade name: Tinuvin 384-2, Ciba Special), polymer stabilizer (trade name: Tinuvin 292, manufactured by Ciba Special Co., Ltd.) 1 part, silicone leveling agent (trade name: Disparon LC915, manufactured by Enomoto Kasei Co., Ltd.) 1 part, methoxypropyl acetate (PMA) / butyl acetate (BA) = 1/1 mixed solution as solvent Main component obtained by kneading 36 parts with Disper for 30 minutes, and polyisocyanate (B) (trade name: Sumidur N3300, manufactured by Sumika Bayer) 26 And kneaded with a disper for 30 minutes, coated on the lowermost layer by air spray so as to be 20 to 30 μm, forcedly dried at 70 ° C. for 40 minutes, cooled, and then formed the outermost layer, did. The specimen was evaluated using the following test method.

(Examples 2-6 and Comparative Examples 1-9)
The components shown as Examples 2 to 6 and Comparative Examples 1 to 9 in Table 1 below were prepared in the same manner as in Example 1 and used as test specimens. The specimen was evaluated using the following test method.

  About each of the obtained test body, each test of the surface characteristic of the produced | generated coating film, a coating-film hardness test, an adhesion test, a chipping test, and a weather-proof adhesion test was implemented. The results of the test obtained are shown in Table 2 below. Each test was performed according to the following method, and the results were evaluated.

"Film performance test"
<Surface characteristics of coating film>
The presence or absence of appearance abnormalities such as discoloration, turbidity, and cracks in the coating film and the presence or absence of adhesion when the coating film was touched were visually evaluated.

<Adhesion test>
Apply 100 blades such as a cutter knife vertically to the surface of the coating, draw 11 parallel lines with a spacing of 2 mm to reach the substrate, and draw 11 parallel lines with a spacing of 2 mm that intersect these parallel lines. An adhesive tape was attached to the film, and the number and state of the films in which 50% or more of the coating film in each square was peeled off were examined by pulling it rapidly at an angle of 45 ° from the coating film.

<Film hardness test>
After applying the paint, apply a load of about 1 kg at a 45 ° angle with a pencil (trade name: Uni, manufactured by Mitsubishi Pencil Co., Ltd.) using a paint film that has passed 72 hours, and a length of 10 to 20 mm. The scratch test was performed 5 times, and the pencil density with less than 2 scratches was indicated.

<Chipping resistance test>
A test plate cooled to −20 ° C. is vertically installed on a stepping stone tester specified in the ASTM D3170 standard, and 100 g of basalt No. 7 crushed stone is hit against the coating film at a pressure of 0.3 MPa. After the test, the peeled coating film was removed with a tape or the like, and the state of the generated coating film scratch was indicated by the following scratch area ratio (%) as the coating film scratch area (a) in the area (b) of the entire test surface. .
* Scratch area ratio (%) = total scratch area (a) / test plate area (b) × 100
A: Less than 0.5% B: 0.5% or more and 1.0% or less x: More than 1.0% <Weather resistance adhesion test>
The adhesion test was carried out after accelerated exposure for 400 hours with an accelerated weathering tester sunshine weather meter and then immersed in warm water at 40 ° C. for 48 hours.

従来のアクリル−シリコン結合のみの１層の塗膜のチッピング傷が全体面積の４〜５％であったのに対し、本発明により生成された２層の塗膜は硬度の低下を抑えたまま、チッピング傷を全体面積の１％以下に保持することが可能となった。

Whereas the conventional chipping scratch of one layer of acrylic-silicon bond only was 4-5% of the total area, the two-layer coating produced according to the present invention suppressed the decrease in hardness. It was possible to keep the chipping scratches at 1% or less of the entire area.

Claims (11)

A coated body having at least two coating layers of paint on the metal surface, and the lowermost layer of the coating layer is modified with an acrylic resin having an amino group and a hydroxyl group, and polycarbonate diol. A polyester resin having a glass transition temperature (Tg) of −75 ° C. or more and −60 ° C. or less and a number average molecular weight (Mw) of 500 g / mol or more and 2500 g / mol or less , a silicon compound and a polyisocyanate compound, A coated body, wherein a mass ratio of the acrylic resin and the polyester resin is 6: 4 to 9: 1 in terms of solid content.   Content of the said polyester resin is 30-40 mass% in the said lowermost layer coating resin, The coating body of Claim 1 characterized by the above-mentioned. The coating material of the outermost layer of the coating layer contains one or both of an acrylic resin and a polyester resin, and a coating film is formed with a curing agent mainly composed of a polyisocyanate or a silane compound. Or the coating body in any one of 2 . The said metal is chrome plating, The coating body in any one of Claims 1-3 characterized by the above-mentioned. In a method for producing a coated body in which at least two coating layers of paint are formed on a metal surface,
Forming a metal layer on the surface of the substrate;
The lowermost layer of the coating layer on the metal is an acrylic resin having an amino group and a hydroxyl group, a glass transition temperature (Tg) of −75 ° C. or more and −60 ° C. or less, and a number average molecular weight (Mw) of 500 g. Containing a polycarbonate diol-modified polyester resin, a silicon compound and a polyisocyanate compound that are not less than / mol and not more than 2500 g / mol , and the mass ratio of the acrylic resin to the polyester resin is 6: 4 to 9: 1 in terms of solid content And a step of applying the coating composition. 6. The method according to claim 5 , further comprising the step of forming an outermost layer on the lowermost layer with a curing agent containing one or both of an acrylic resin and a polyester resin and having a polyisocyanate or a silane compound as a main component. The manufacturing method of the coating body of description. The said metal is chrome plating, The manufacturing method of the coating body of Claim 5 or 6 characterized by the above-mentioned. A coating composition for metal that forms at least two coating layers of a coating on the surface of a metal, wherein the lowermost coating in the coating layer is modified with an acrylic resin having an amino group and a hydroxyl group, or polycarbonate diol. A polyester resin having a glass transition temperature (Tg) of −75 ° C. or more and −60 ° C. or less and a number average molecular weight (Mw) of 500 g / mol or more and 2500 g / mol or less , a silicon compound and a polyisocyanate compound. A metal coating composition, wherein the mass ratio of the acrylic resin and the polyester resin is 6: 4 to 9: 1 in terms of solid content. The metal coating composition according to claim 8 , wherein the content of the polyester resin is 30 to 40% by mass in the lowermost coating resin. The outermost layer of the coating material of the coating layer contains one or both of acrylic and polyester resins, claim 8, characterized in that to form a coating film with a curing agent composed mainly of polyisocyanate or a silane compound or 10. The metal coating composition according to any one of 9 above. The metal coating composition according to any one of claims 8 to 10 , wherein the metal is chrome plating.