JP2005220291A - Metallic base coating composition and method for forming layered coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metallic coating film free from the variation of hue caused by the interlayer mixing of a metallic base coating film and a clear coating film in the case of coating by a two-coat one-bake coating method, having excellent hue stability of the coating material and dense glittering appearance of the coating film and exhibiting flip-flop property. <P>SOLUTION: The solvent-type metallic base coating composition contains (A) a urea-modified acrylic resin, (B) a urethane-modified polyester resin, (C) a curing agent, (D) a glittering pigment, (E) a color pigment and (F) a dispersion assistant for the color pigment. The weight ratio of (A) the urea-modified acrylic resin to (B) the urethane-modified polyester resin is 60/40 to 95/5 in solid basis. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a solvent-type metallic base coating composition for forming a top coating film of an automobile body or the like and a method for forming a laminated coating film using the coating composition.

  In recent years, metallic coating films formed by a so-called two-coat one-bake method, in which a clear coating film is formed on a metallic base coating film by a wet-on-wet method and simultaneously baked, are increasing as an automotive top coating film.

  In the case of the 2-coat 1-bake coating method, the clear paint is applied onto the metallic base coating film as described above, but the appearance that can be obtained from the metallic base coating film is obtained by applying the clear paint. It may be slightly different from the appearance. This can be prevented by applying a little temperature to the metallic base coating film (so-called preheating). However, when the 2-coat 1-bake method is adopted, it is possible to form the coating film wet-on-wet without preheating. It is a merit of adoption, and it is common to apply a clear paint continuously after forming a metallic base coating film from the viewpoint of work efficiency and energy saving. That is, the slight change in the appearance when the clear paint is applied has been sacrificed in a sense.

  Such slight changes in appearance are thought to be caused by familiarity at the interface during clear coating, and measures to prevent such familiarity are addition of additives to paint and modification to vehicle resin Is being considered.

  For example, as a disclosure of use of a resin having a urea group in the base paint, JP-A-8-283612 discloses a polyurethane polyurea crosslinked fine particle dispersion obtained by using a specific polyol compound, a polyisocyanate compound and a polyamine compound. An aqueous base coat resin composition comprising a body (I), an aqueous resin (II) having a hydroxyl group and / or a carboxyl group, and an aqueous curing agent (III) having reactivity with a hydroxyl group and / or a carboxyl group is described. ing. In this coating material, urea groups are introduced into the resin component, but since it is an aqueous coating, preheating is always required after metallic base coating, which is different from two-coat one-bake coating with a solvent-based coating that does not preheat.

  Japanese Patent Application Laid-Open No. 2003-82280 describes a resin composition for a colored paint containing a polyester resin having a hydroxyl group, a curing agent, internal cross-linking fine particles, and a urea rheology control agent. This paint is for a paint system based on a polyester resin, and is not a study on an acrylic resin and a solvent-based base paint.

  Furthermore, JP-A-10-174929 describes a coating method using a transparent topcoat composition containing an acrylic resin having a specific functional group and / or urea functional group and an aminoplast crosslinking agent. This paint is an improvement of the clear paint, not a solvent-based metallic base paint.

  On the other hand, in Japanese Patent Application Laid-Open No. 2002-126627, a pigment dispersion paste obtained by previously dispersing a pigment dispersant and a pigment substantially free of a volatile basic substance is blended with an aqueous intermediate coating or an aqueous base coating. A method for forming a multilayer coating film used in this manner is disclosed. Since this paint is a water-based paint and the above-mentioned preheating is an essential paint system, there are few problems caused by mixing with the clear coating film.

  In any case, existing metallic base paints are not sufficient in terms of flip-flop property (hereinafter referred to as FF property) in which the brightness of the coating film (whiteness of the coating film) changes depending on the viewing angle. In particular, it was difficult to form a paint film having a high density and a high FF property of the luster material with a medium color that increases the pigment concentration (PWC).

JP-A-8-283612 JP 2003-82280 A JP-A-10-174929 JP 2002-126627 A

Metallic paint with a large hue difference between when viewed from the highlight position and when viewed from the shade position, that is, with high FF properties, excellent adhesion, and excellent hue stability when storing paint It is hoped to provide.

In particular, the medium-colored metallic paint film is caused by the high PWC of the metallic base paint, or the hue variation due to the mixture of the metallic base paint film and the clear paint film when applied by the 2-coat 1-baking method. Therefore, the design of a new metallic base paint is desired since the appearance of the coating film and the glossiness are likely to be low (it tends to give a mushy feeling) and the glossiness is likely to be lowered.

The present invention relates to a metallic base coating composition for satisfying the above requirements and a method for forming a laminated coating film using the coating composition, and provides a novel solvent-based metallic base coating composition. It is providing the formation method of the laminated coating film using a coating composition.

  That is, the present invention includes a urea-modified acrylic resin (A), a urethane-modified polyester resin (B), a curing agent (C), a glitter pigment (D), a color pigment (E), and a color pigment dispersion aid (F). A solvent-type metallic base coating composition containing, wherein the solid content weight ratio of the urea-modified acrylic resin (A) and the urethane-modified polyester resin (B) is 60/40 to 95/5. An object of the present invention is to provide a solvent-type metallic base coating composition.

Further, the present invention provides a solvent-type metallic base coating composition, wherein the color pigment dispersion aid is selected from melamine co-condensed acrylic resins, basic pigment dispersants and mixtures thereof. .

Furthermore, the present invention provides a solvent-type metallic base coating composition, wherein the curing agent (C) is a melamine resin.

Furthermore, in the method for forming a laminated coating film in which a solvent-based metallic base coating composition and a clear coating are sequentially formed on a substrate by wet-on-wetting, the solvent-based metallic base coating composition is a urea-modified acrylic resin (A). And a urethane-modified polyester resin (B), a curing agent (C), a bright pigment (D), a color pigment (E), and a color pigment dispersion aid (F). Is to provide.

The solvent-based metallic base coating composition of the present invention is excellent in hue stability, the obtained multilayer coating film is excellent in adhesion, and can exhibit a fine glitter feeling that the glitter pigment is uniformly dispersed. . In addition, since the metallic base coating film and the clear coating film are not mixed to cause color reversion or appearance to deteriorate, a metallic coating film can be formed industrially stably.
Hereinafter, the present invention will be described in more detail.

  The solvent-type metallic base coating composition of the present invention comprises a urea-modified acrylic resin (A), a urethane-modified polyester resin (B), a curing agent (C), a glitter pigment (D), a color pigment (E), and a color pigment dispersion. A solvent-type metallic base coating composition containing an auxiliary agent (F), wherein a solid weight ratio of the urea-modified acrylic resin (A) and the urethane-modified polyester resin (B) is 60/40 to 95 / 5.

When the content of the urea-modified acrylic resin (A) is less than the lower limit, the coating film appearance is improved, but the FF property is lowered. When the content exceeds the upper limit, the FF property is improved, but the coating film appearance (skin feeling) is lowered. . The solid content weight ratio is more preferably 65/35 to 92/8, and particularly preferably 70/30 to 90/10. On the other hand, when the urethane-modified polyester resin (B) is not within the above range, the interlaminar property at the interface with the clear coating film is lowered, and as a result, when the clear coating film is formed, color reversion occurs, which is not preferable.

Urea-modified acrylic resin (A)
As said urea modified acrylic resin (A), the acrylic resin which has a urea bond group (urea group) -NH-CO-NH- can be mentioned. Based on the solid content of the urea-modified acrylic resin (A), the urea group-NH-CO-NH- is, for example, a urea group introduction (modified) component amount in the case of using the components described later is 1 to 15% by weight. It is preferable that it is 2 to 12% by weight. When the upper limit is exceeded, the appearance (skin feel) when the coating film is formed is lowered, and when the lower limit is not reached, the dense feeling of the FF property and the glittering face material is lowered. Particularly preferred is 3 to 10% by weight. However, there are no particular problems with the synthetic components and techniques, and it is important as an effect obtained after the coating film is prepared to use an acrylic resin having a urea group introduced in the coating composition of the present invention.

  For example, the urea-modified acrylic resin (A) can be formed from a reaction between (1) an isocyanate compound, (2) a hydroxyl group-containing acrylic resin, and (3) an amine compound. Examples of the component include (1) an isocyanate compound and (3) an amine compound.

  Specifically, among the three components described above, the isocyanate compound (1) and the hydroxyl group-containing acrylic resin (2) synthesized in advance are used as the synthesis method, and the isocyanate group of the compound (1) is based on the hydroxyl equivalent of the acrylic resin. A method of reacting an amine compound (3) with an unreacted isocyanate group after reacting to be excessive, or an amine compound such that the amine value is less than or equal to the isocyanate group of the isocyanate compound (1) A method of reacting the hydroxyl group-containing acrylic resin (2) with an unreacted isocyanate group after reacting (3), urea functionality such as acrylic monomer and urea functional acrylic acid or alkyl ester of methacrylic acid Synthesized by copolymerization with vinyl monomers or using isocyanate group-containing monomers. Various methods are conceivable, such as that reacting an amine compound to an acrylic resin. The urea-modified acrylic resin (A) as the reaction product may be produced by a method obtained by synthesis in the presence of another binder, a curing agent and / or a binder or a curing agent used in the paint. Can do.

  The urea-bonding group forms a pseudo-network structure due to hydrogen bonding in the paint, and can exhibit thixotropic properties (hereinafter referred to as thixotropy) in the paint. It is preferable because it can be incorporated into The thixotropy developed by the urea bonding group in the coating composition is very excellent because it is not affected at all or hardly by the water and / or the organic solvent contained in the coating composition. Further, the thixotropy developed by the urea bonding group is hardly affected by temperature, and is extremely effective at a temperature of 60 ° C. to 260 ° C., that is, a high temperature such as a temperature at which a baking type paint is generally cured. Sex can be maintained.

  Further, the urea-modified acrylic resin (A) from the above component examples (1) to (3) is produced by the equivalent of the isocyanate group present in the starting component to the isocyanate group present in the starting component. Using the reactants in such a ratio that the ratio (isocyanate reactive groups / isocyanate groups) is 0.5-2, preferably 0.7-1.5, more preferably 0.8-1.2, This is accomplished in a known manner in one or more stages. In particular, in the reaction between the diisocyanate and the amine compound, generally either the diisocyanate or the amine compound can be used in excess of the stoichiometric amount, for example, the number of amino groups of the amine compound and the number of isocyanate groups of the diisocyanate. The ratio can be 0.7 to 1.5, preferably 0.9 to 1.1.

  The reaction between the diisocyanate and the amine compound can be carried out by any method selected by generally mixing these reaction components and raising the temperature as desired. This reaction is desirably performed at a temperature of 10 to 150 ° C, preferably 20 to 80 ° C. In general, the reaction components can be mixed by an arbitrarily selected method, but it is usually desirable to add diisocyanate to the amine compound, and this addition can be carried out in several steps as desired. In general, this reaction is carried out in the presence of a solvent such as an aliphatic hydrocarbon such as acetone, methyl isobutyl ketone, 1-methoxy-2-propanol, benzene, toluene, xylene or petroleum ether.

  The urea-modified acrylic resin (A) preferably has a weight average molecular weight (Mw) of 3000 to 150,000, more preferably 4000 to 130,000. If the lower limit is not reached, the coating workability and the interlaminarity with the clear coating film deteriorate, and if the upper limit is exceeded, the non-volatile content at the time of coating becomes too low and the workability deteriorates. A range of 5,000 to 120,000 is particularly preferred from the viewpoint of coating film appearance. In the present specification, the molecular weight is determined by the GPC method using styrene polymer as a standard.

  The urea-modified acrylic resin (A) preferably has a hydroxyl value (solid content) of 30 to 180, and more preferably 50 to 150. When the upper limit is exceeded, the water resistance decreases when the coating film is formed, and when the lower limit is exceeded, the curability of the coating film decreases. Furthermore, the urea-modified acrylic resin (A) preferably has an acid value (solid content) of 5 to 30 mgKOH / g, and more preferably 8 to 25 mgKOH / g. When the upper limit is exceeded, the water resistance decreases when the coating film is formed, and when the lower limit is exceeded, the curability of the coating film decreases.

  Further, the urea-modified acrylic resin (A) preferably has a glass transition temperature (Tg) of −10 to 30 ° C., more preferably 0 to 25 ° C. If it is out of the above range, the physical properties of the coating film are lowered.

  Examples of the isocyanate compound (1) include alicyclic, aromatic group-containing aliphatic or aromatic compounds. Examples of suitable isocyanate compounds include diisocyanate or its isocyanurate (triisocyanate of diisocyanate).

  As said diisocyanate, what contains generally 5-24, preferably 6-18 carbon atoms can be used.

  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′-diisocyanatodicyclodicyclomethane, ω, ω′-dipropyl ether diisocyanate, thiodipropyl diisocyanate Cyclohexyl-1,4-diisocyanate, 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, diphenylmethane-4,4'-diisocyanate and the like.

  2,4-diisocyanatotoluene and / or 2,6-diisocyanatotoluene, 4,4′-diisocyanatodiphenylmethane and 1,4-diisocyanatoisopropylbenzene, cyclohexyl-1,4-diisocyanate, Aromatic diisocyanates such as toluene diisocyanate and hexamethylene diisocyanate can also be used. Furthermore, mixtures of these compounds can also be used.

  As said isocyanurate, the trimer of the diisocyanate mentioned above can be mentioned. The isocyanate may be a diisocyanate or a mixture of trimers.

  The hydroxyl group-containing acrylic resin (2) is obtained by copolymerizing a hydroxyl group-containing ethylenically unsaturated monomer and another ethylenically unsaturated monomer. The hydroxyl group-containing acrylic resin (2) preferably has a number average molecular weight (Mn) of 1000 to 8000, and more preferably 1200 to 6000. If the lower limit is not reached, the coating workability and the interlaminarity with the clear coating film deteriorate, and if the upper limit is exceeded, the non-volatile content at the time of coating becomes too low and the workability deteriorates. The number average molecular weight is particularly preferably in the range of 1500 to 5000 from the viewpoint of coating film appearance.

  The hydroxyl group-containing acrylic resin (2) preferably has a hydroxyl value (solid content) of 40 to 180, and more preferably 50 to 150. When the upper limit is exceeded, the water resistance decreases when the coating film is formed, and when the lower limit is exceeded, the curability of the coating film decreases. Furthermore, it preferably has an acid value (solid content) of 7 to 32 mgKOH / g, and more preferably 10 to 27 mgKOH / g. When the upper limit is exceeded, the water resistance decreases when the coating film is formed, and when the lower limit is exceeded, the curability of the coating film decreases.

  The hydroxyl group-containing acrylic resin (2) can be obtained by copolymerizing a hydroxyl group-containing ethylenically unsaturated monomer and another ethylenically unsaturated monomer. Based on the total amount of the ethylenically unsaturated monomer used for the production, the hydroxyl group-containing ethylenically unsaturated monomer is 5 to 60% by weight, preferably 8 to 50% by weight, and the other ethylenically unsaturated monomer is 95 to 40%. % By weight, preferably 92-50% by weight. If the content of the hydroxyl group-containing ethylenically unsaturated monomer is below the lower limit, the production stability is lowered. If the upper limit is exceeded, the water resistance of the resulting coating film will be reduced.

  Specific examples of the hydroxyl group-containing ethylenically unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, allyl alcohol, and methacryl alcohol. Examples include adducts of hydroxyethyl (meth) acrylate and ε-caprolactone. Among these, it is preferable to use a long-chain hydroxyl group-containing monomer as the hydroxyl group-containing monomer in terms of improving chipping resistance. Examples thereof include 4-hydroxybutyl (meth) acrylate, adducts of 2-hydroxyethyl (meth) acrylate and ε-caprolactone.

  Although it does not specifically limit as said other ethylenically unsaturated monomer, First, the ethylenically unsaturated monomer which has a carboxyl group can be mentioned. Examples thereof include (meth) acrylic acid derivatives (e.g., acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, acrylic acid dimer, and α-hydro-ω-((1 -Oxo-2-propenyl) oxy) poly (oxy (1-oxo-1,6-hexanediyl)) etc.); and unsaturated dibasic acids, their half esters, half amides and half thioesters (eg maleic acid, Fumaric acid, itaconic acid, its half esters, half amides and half thioesters).

  Furthermore, examples other than the above monomers include (meth) acrylate ester monomers (for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) ) Acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, phenyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, dicyclopentadienyl ( Meth) acrylate and dihydrodicyclopentadienyl (meth) acrylate), polymerizable aromatic compounds (eg styrene, α-methyl styrene, vinyl ketone, t-butyl styrene, parachlorostyrene and Vinyl naphthalene etc.), polymerizable nitriles (eg acrylonitrile and methacrylonitrile etc.), α-olefins (eg ethylene and propylene etc.), vinyl esters (eg vinyl acetate and vinyl propionate etc.), dienes (eg butadiene and isoprene etc.) If necessary, an isocyanate group-containing monomer can be mentioned. Such other ethylenically unsaturated monomers can be used alone or in admixture of two or more.

  A hydroxyl group-containing acrylic resin can be obtained by radical copolymerization of each of the above ethylenically unsaturated monomers, and the polymerization method may be a normal method described in known literature such as solution radical polymerization. . For example, a method of stirring while dropping a suitable radical polymerization initiator and a monomer mixed solution into a suitable solvent at a polymerization temperature of 60 to 160 ° C. over 2 to 10 hours can be mentioned. The radical polymerization initiator that can be used here is not particularly limited as long as it is usually used in polymerization, and examples thereof include azo compounds and peroxides. In general, the amount of initiator relative to the total amount of unsaturated compounds is generally from 0.1 to 18% by weight, preferably from 0.5 to 15% by weight.

  Moreover, the solvent which can be used here will not be specifically limited if it does not have a bad influence on reaction, For example, alcohol, a ketone, a hydrocarbon type solvent, etc. are mentioned. Further, in order to adjust the molecular weight, a mercaptan such as lauryl mercaptan and a chain transfer agent such as α-methylstyrene dimer can be used as necessary.

  As a typical example of the amine compound (3), which is the third component used in the production of the urea-modified acrylic resin (A), generally 55 or less carbon atoms, preferably 1 to 24, more preferably 1 And ether amines and primary amines containing ˜12 carbon atoms.

  The ether amine may contain one or more hydroxyl groups, such as 2-methoxyethylamine, 2-ethoxyethylamine, 3-methoxy-1-propylamine, 1-methoxymethylpropylamine, 1,1 -Dimethoxy-2-propylamine, 3-ethoxy-1-propylamine, 3-butoxy-1-propylamine, 3- (2-ethylhexyloxy) -1-propylamine, 3-tridecyloxypropylamine, 3- Stearyloxypropylamine, p-methoxybenzylamine, 3,4-dimethoxybenzylamine, p-methoxyphenylethylamine, 3,4-dimethoxyphenyl-ethylamine, 9-phenoxy-4,7-dioxanon-1-amine, 2-Methyl-4-methoxyaniline, 2,5-di Toxi-aniline, furfurylamine, tetrahydrofurfurylamine, 2- (4-morpholinyl) ethylamine, 4- (3-aminopropyl) morpholine, 2,2'-aminoethoxyethanol, 4,7-dioxadecane-1,10-diamine 4,9-dioxadecane-1,12-diamine, 7-methyl-4,10-dioxatridecane-1,13-diamine, 4,7,10-trioxatridecane-1,13-diamine and bis (3-aminopropyl) polytetrahydrofuran (molecular weight about 750). A mixture of the above ether amines can also be used.

  Further, as the primary amine, an amine having one or more primary amino groups and one or more ethers and / or hydroxyl groups can be used, for example, ethanolamine, 6-aminohexanol, p-methoxybenzylamine. , Methoxypropylamine, 3,4-dimethoxyphenylethylamine, 2,5-dimethoxyaniline, furfurylamine, tetrahydrofurfurylamine, benzylamine, ethylamine, n-propylamine, sec-propylamine, n-butylamine, sec-butylamine , Tert-butylamine, n-pentylamine, α-methylbutylamine, α-ethylpropylamine, β-ethylbutylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamino , Aniline, primary amines such as hexamethylene diamine and the like. The above amine compounds can be mixed and used.

  Content of the said urea modified acrylic resin (A) is 20-65 weight part with respect to 100 weight part of coating resin solid content. When the content is below the lower limit, the FF property is lowered, and when the content exceeds the upper limit, the appearance is lowered. Preferably it is 25-60 weight part.

Urethane-modified polyester resin (B)
As the urethane-modified polyester resin (B), a hydroxyl group-containing polyester resin including a mixture of an acid component such as a polyvalent carboxylic acid and / or an acid anhydride and a polyhydric alcohol, and a diisocyanate compound are used. Examples thereof include resins obtained by reacting at a ratio, and it is preferable that one molecule has two or more hydroxyl groups.

  The urethane-modified polyester resin (B) preferably has a weight average molecular weight (Mw) of 2000 to 20000, more preferably 3000 to 15000. If the lower limit is not reached, the coating workability and the interlaminarity when wet-on-wet are applied are reduced, and if the upper limit is exceeded, the non-volatile content of the paint becomes too low and the coating workability is reduced.

  The urethane-modified polyester resin (B) preferably has a hydroxyl value (solid content) of 30 to 180, and more preferably 40 to 160. When the upper limit is exceeded, the water resistance in the case of a coating film is lowered, and when the lower limit is exceeded, the curability of the coating film is lowered. Moreover, it is preferable that it has an acid value (solid content) of 2-20 mgKOH / g, and it is still more preferable that it is 3-15 mgKOH / g. When the upper limit is exceeded, the water resistance in the case of a coating film is lowered, and when the lower limit is exceeded, the curability of the coating film is lowered.

  Furthermore, the urethane-modified polyester resin (B) preferably has a glass transition temperature (Tg) of −10 to 70 ° C., more preferably −5 to 50 ° C. When the glass transition point (Tg) is lower than the lower limit, the coating film hardness is lowered. When the glass transition point (Tg) is higher than the upper limit, the solid content of the paint is lowered and the coating workability is lowered.

  In general, a polyester resin can be produced by polycondensation of an acid component such as a polyvalent carboxylic acid and / or an acid anhydride and a polyhydric alcohol.

  The polyvalent carboxylic acid and / or acid anhydride is not particularly limited. For example, phthalic acid, isophthalic acid, phthalic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, methyl Tetrahydrophthalic acid, methyltetrahydrophthalic anhydride, hymic anhydride, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, terephthalic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, adipic acid And azelaic acid, sebacic acid, succinic acid, succinic anhydride, dodecenyl succinic acid, dodecenyl succinic anhydride and the like.

  The polyhydric alcohol is not particularly limited, and examples thereof include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, neopentyl glycol, 1,2-butanediol, and 1,3-butanediol. 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 2,2-dimethyl-3-hydroxypropyl-2,2 -Dimethyl-3-hydroxypropionate, 2,2,4-trimethyl-1,3-pentanediol, polytetramethylene ether glycol, polycaprolactone polyol, glycerin, sorbitol, annitol, trimethylolethane Trimethylol propane, trimethylol butane, hexanetriol, pentaerythritol, dipentaerythritol and the like.

  As other reaction components other than the polyvalent carboxylic acid and / or acid anhydride and the polyhydric alcohol component, monocarboxylic acid, hydroxycarboxylic acid, lactone and the like may be contained. Moreover, you may contain dry oil, semi-dry oil, and those fatty acids. Specific examples include monoepoxide compounds such as Cardura E (manufactured by Shell Chemical Co.) and lactones. The lactones can be subjected to ring-opening addition to polyesters of polyvalent carboxylic acids and polyhydric alcohols to form graft chains. For example, β-propiolaclone, dimethylpropiolactone, butyllactone, γ- Examples include valerolactone, ε-caprolactone, γ-caprolactone, γ-caprolactone, crotolactone, δ-valerolactone, and δ-caprolactone, among which ε-caprolactone is most preferable.

  The diisocyanate compound to be reacted with the hydroxyl group-containing polyester resin is a compound having two or more free isocyanate groups in one molecule, and specifically, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate and trimethylene diisocyanate. Aliphatic diisocyanates such as: isophorone diisocyanate, alicyclic diisocyanates such as methylene bis (cyclohexyl isocyanate) and cyclohexane diisocyanate; aromatic diisocyanates such as xylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate and biphenylene diisocyanate; These can be used alone or in combination of two or more.

  Particularly preferred diisocyanate compounds are aliphatic diisocyanates, specifically hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4,4-diisocyanate, methylcyclohexane diisocyanate and the like. Can be mentioned.

  The reaction conditions of the usual urethanization reaction can be widely applied to the reaction between the hydroxyl group-containing polyester resin and the diisocyanate compound.

  Furthermore, content of the said urethane-modified polyester resin (B) is 5-40 weight part on the basis of 100 weight part of coating resin solid content. When the content is less than the lower limit, the interlaminar property is lowered, and when the content exceeds the upper limit, the FF property is lowered. Preferably it is 8-25 weight%.

Curing agent (C)
As said hardening | curing agent (C), although a melamine resin, a block isocyanate compound, etc. are mentioned, a melamine resin is preferable. The melamine resin is not particularly limited, and a methylated melamine resin, a butylated melamine resin, or a methyl / butyl mixed melamine resin can be used. Examples include “Cymel-303” and “Cymel 254” manufactured by Nippon Cytec Co., Ltd., “Uban 20N60” and “Uban 128” manufactured by Mitsui Chemicals, and “Summar Series” manufactured by Sumitomo Chemical Co., Ltd.

  The amount of the melamine resin used is preferably 20 to 100 parts by weight with respect to 100 parts by weight of the solid content of the film-forming resin such as urea-modified acrylic resin (A) and urethane-modified polyester resin (B). More preferably, it is 40-90 weight part. When the amount used is less than the lower limit, the curability becomes insufficient, and when the amount exceeds the upper limit, the cured film becomes too hard and the chipping property is lowered when the coating film is formed.

  Further, the blocked isocyanate compound is obtained by adding a blocking agent to polyisocyanate, and the blocking agent is dissociated by heating to generate an isocyanate group, which reacts with the functional group in the acrylic resin and cures. It is done.

  The polyisocyanate is not particularly limited, and examples thereof include aliphatic isocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; 1,3-cyclopentane diisocyanate, 1,4 -Aliphatic cyclic isocyanate such as cyclohexane diisocyanate, 1,2-cyclohexane diisocyanate, isophorone diisocyanate, norbornane diisocyanate methyl; aromatic isocyanate such as xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate; These nurate bodies and mixtures can be used.

  Examples of the blocking agent include methanol, ethanol, n-propanol, isopropanol, furfuryl alcohol, alkyl-substituted furfuryl alcohol, aliphatic or aromatic alcohols such as benzyl alcohol, phenols, methyl ethyl ketone oxime, Examples include oximes such as methyl isobutyl ketone oxime, acetone oxime and cyclohexane oxime, active methylene compounds such as acetylacetone, ethyl acetoacetate and ethyl malonate, and captolactam.

  The compounding quantity in the case of using the said block isocyanate compound is 20-100 weight with respect to 100 weight part of solid content of film forming resin, such as a urea modified acrylic resin (A) and a urethane modified polyester resin (B). Outside the above range, curing is insufficient.

Bright pigment (D)
The shape of the glitter pigment (D) is not particularly limited and may be further colored. For example, the average particle diameter (D50) is 2 to 50 μm and the thickness is 0.1 to 5 μm. The scaly thing which is is preferable. Those having an average particle diameter in the range of 10 to 35 μm are excellent in glitter and are more preferably used.

  The pigment concentration (PWC) in the paint of the glitter pigment (D) is generally 23.0% or less. When the upper limit is exceeded, the appearance of the coating film deteriorates. Preferably, it is 0.01% to 20.0%, and more preferably 0.01% to 18.0%.

  Examples of the glitter pigment (D) include non-colored or colored metallic glitter materials such as metals or alloys and mixtures thereof, interference mica powder, colored mica powder, white mica powder, graphite, colorless or colored flat pigments, and the like. Can be mentioned. Excellent dispersibility and high transparency can be formed, so there are no colored or colored metallic glitter materials such as metals or alloys and their mixtures, interference mica powder, colored mica powder, and white mica powder. preferable. Specific examples of the metal include aluminum, aluminum oxide, copper, zinc, iron, nickel, tin and the like.

Color pigment (E)
The solvent-type metallic base coating composition of the present invention further contains a color pigment. The color pigments may be those conventionally used in this type of coating composition. Examples of such pigments include organic azo chelate pigments, insoluble azo pigments, condensed azo pigments, diketopyrrolopyrrole pigments. Benzimidazolone pigments, phthalocyanine pigments, indigo pigments, perinone pigments, perylene pigments, dioxane pigments, quinacridone pigments, isoindolinone pigments, metal complex pigments, etc. Examples include yellow iron oxide, bengara, carbon black, and titanium dioxide. Furthermore, an extender pigment may be included as necessary. As extender pigments, calcium carbonate, barium sulfate, clay, talc and the like may be used in combination.

  The total pigment concentration (PWC) in the metallic paint including the glitter pigment (D) and all other pigments (colored pigment and extender pigment) is 0.1 to 50%, preferably 0.8. It is 5% to 40%, and more preferably 1.0% to 30%. When the upper limit is exceeded, the appearance of the coating film deteriorates.

Coloring pigment dispersion aid (F)
The solvent-type metallic base coating composition of the present invention comprises, as a pigment dispersion paste of a colored pigment (E), one or more pigment dispersants selected from melamine co-condensed acrylic resins or basic pigment dispersants, and a color pigment (E ) And, if necessary, a dispersion of extender pigments. If the color pigment dispersion aid (F) is missing, the transparency and adhesion of the coating film and the paint stability after dispersion are poor.

Examples of the melamine co-condensed acrylic resin include an acrylic copolymer obtained by solution polymerization of a hydroxyl group-containing ethylenically unsaturated monomer, an acid group-containing ethylenically unsaturated monomer and, if necessary, another ethylenically unsaturated monomer. Examples thereof include those obtained by co-condensing a melamine resin with the coalescence.

Examples of the co-condensation of the melamine resin include a method of condensing the acrylic copolymer and the melamine resin in an appropriate solvent while stirring at a condensation temperature of 50 to 120 ° C. for 0.5 to 5 hours. .

As for the said melamine resin, the melamine resin described by the said hardening | curing agent (C) can be mentioned. As the melamine resin, although it overlaps, for example, methylated melamine resin, butylated melamine resin or methyl / butyl mixed melamine resin can be used.

As an ethylenically unsaturated monomer used for obtaining the acrylic copolymer, a hydroxyl group-containing ethylenically unsaturated monomer described in the hydroxyl group-containing acrylic resin contained in the urea-modified acrylic resin (A), an acid group-containing Ethylenically unsaturated monomers and other ethylenically unsaturated monomers can be used.

The resulting acrylic copolymer can have a number average molecular weight (Mn) in the range of about 700 to 10,000, preferably about 1,000 to 8,000. Below the lower limit, the stability of the pigment-dispersed paste decreases, and above the upper limit, the dispersion efficiency decreases.

The basic pigment dispersant is a linear polymer having a pigment affinity portion composed of a basic pigment affinity group at least at one end of the main chain (including both ends) by a block or graft structure. The basic pigment affinity group is a tertiary amino group, a quaternary ammonium group or a heterocyclic group having a basic nitrogen atom, and a linear polymer such as polyacrylate, polyurethane, polyester, or these Any one of the modified products may be mentioned.

Moreover, what has 2-3000 said basic pigment affinity groups in 1 molecule is preferable. If it is less than 2, the F / F value may be too high, and if it exceeds 3000, the viscosity may be too high and handling may be difficult. More preferably, it is 5 to 1500.

The basic pigment dispersant preferably has a number average molecular weight of 1,000 to 1,000,000. If it is less than 1000, the F / F value may be too high, and if it exceeds 1000000, the viscosity may be too high and handling may be difficult. More preferably, it is 2000-500000.

As the pigment dispersant, a commercially available one can be used. Examples of the commercially available products include Disperbyk 161, Disperbyk 166, Disperbyk 182, Disperbyk 183, Disperbyk 185 (all manufactured by Big Chemie), Solsperse 5000, Solsperse 24000, Solsperse 32550 (all manufactured by Abyssia) it can.

The solvent-type metallic base coating composition of the present invention is obtained by previously mixing and dispersing a color pigment, the above-mentioned pigment dispersion aid (F) and an extender pigment as necessary, and obtaining it as a pigment paste. It is preferable to manufacture in order of mixing with an organic solution or the like. The mixing method of the pigment and the pigment dispersion aid (F) is not particularly limited, but may be performed using normal low-shear stirring, high-shear stirring with a homogenizer, or ultrasonic waves. .

The mixing ratio of the pigment dispersion aid (F) and the color pigment or extender pigment varies depending on the type of pigment, but the dispersion resin (solid content) is usually about 100 parts by weight of the color pigment or extender pigment. It is desirable that the amount be 0.1 to 1,000 parts by weight, preferably about 0.5 to 500 parts by weight. The mixing and dispersion can be carried out by a conventionally known method such as pebble mill dispersion, sand mill dispersion, roll mill dispersion or shaker dispersion.

As a method of dispersing the pigment dispersion aid (F) and the color pigment or extender pigment, since the dispersion ability and dispersion efficiency are high, the output density is 2.6 KW or more per 1 L (liter) of capacity, and 6.7 m. For example, a dispersion method using a wet bead mill operated at a stirrer outer speed of at least a second per second, and a power density of 2.6 to 4.2 KW per liter of capacity and a stirrer outer speed of from 9 to 20 m / second. A dispersion method using a wet bead mill is desirable. Other conditions are appropriately set depending on the type and size (capacity) of the apparatus, the type and amount of the dispersion sample (mixture of resin, pigment, and water), the peripheral speed of the stirrer, the flow rate of the dispersion sample, and the like. However, other methods may be used as long as the dispersion state can be maintained. For example, a dispersion method using a crushing force of a stirring blade such as a homodisper, or a dispersion method using a bead collision such as a paint conditioner or a sand mill. And so on.

The above-mentioned wet bead mill uses a liquid feed pump to feed a sample into the disperser, and the bead, which is the dispersion medium filled inside the disperser, is rotated by the agitating blade while colliding between the beads, the agitating blade, the inner wall of the disperser, etc. Then, if necessary, circulate as needed and further disperse, and then separate and collect only the sample through the slit. Examples of such wet bead mills include dyno mill, bore mill, visco mill, motor mill, etc. Is mentioned. In addition, a horizontal type of wet bead mill has heretofore been the mainstream, but a vertical type has recently appeared, which is preferable because the dispersion efficiency is further improved in that the beads are not biased.

The type of beads used in the wet bead mill is not particularly limited, and examples thereof include glass beads, oxidized zirconia beads, steel beads, and ceramic beads. The filling amount of the beads is not particularly limited, but as an example, 20 to 90% of the internal volume of the apparatus is desirable, and 70 to 85% is most desirable.

As the size of the beads becomes finer, the dispersion ability increases. However, since a large pressure is required for separating the beads with a filter, an appropriate range, for example, a diameter of 0.05 to 3 mm, preferably a diameter of 0.1. Use ~ 1 mm beads.

For example, the flow rate of the dispersion sample is usually 10 to 1000 ml / min, preferably 50 to 500 ml / min per 1 L of the remaining volume after subtracting the volume of beads filled in the dispersion container. The total residence time is generally 10 minutes or longer, preferably 30 minutes to 5 hours. For example, when a wet bead mill having a dispersion container with a capacity of 2 L is filled with beads having a capacity of 1 L, the remaining capacity after subtracting the capacity of the beads filled in the dispersion container is 1 L. When the pigment mixture is circulated at a rate of 100 ml / min, the residence time in the dispersion container is 10 minutes, and when this is circulated four times, the total residence time in the dispersion container is 40 minutes.

According to the above dispersion method, sufficient dispersion force is efficiently given to the pigment in the presence of the dispersion resin, so that the particle diameter of the pigment becomes fine and dispersion stabilization by the resin coating can be achieved simultaneously. The pigment dispersion obtained in this way is excellent in storage stability. In addition, these pigment dispersions have already adsorbed the resin to the pigment, and by removing and concentrating the dispersion medium such as the solvent, the pigment and the resin are further strongly adsorbed. In addition, even when other resins and solvents are added and processed, excellent storage stability can be maintained.

Other Components The solvent-based metallic base coating composition of the present invention can contain other film-forming resins. The other film-forming resin is not particularly limited, and a film-forming resin such as an acrylic resin, a polyester resin, an alkyd resin, an epoxy resin, or a urethane resin can be mentioned as a preferable one. Two or more species can be used in combination.

  In addition, a viscosity control agent may be added to the solvent-type metallic base coating composition in order to ensure coating workability. For example, crosslinkable or non-crosslinkable resin particles, fatty acid amide swelling dispersions, amide fatty acids, polyamides such as long-chain polyaminoamide phosphates, polyethylenes such as colloidal swelling dispersion of oxidized polyethylene, etc. Organic bentonite-based materials such as organic acid smectite clay and montmorillonite, inorganic pigments such as aluminum silicate and barium sulfate, and flat pigments that develop viscosity depending on the shape of the pigment.

  In the solvent-type metallic base paint composition used in the present invention, in addition to the above-mentioned components, additives usually added to the paint, such as surface conditioners, thickeners, antioxidants, UV inhibitors, antifoaming An agent or the like can be blended. These amounts are within the well-known range of those skilled in the art.

  The solid content at the time of application of the solvent-based metallic base coating composition used in the present invention is 20 to 45% by weight, preferably 21 to 40% by weight. If the upper limit is exceeded, the viscosity is too high and the appearance of the coating film is lowered. If the lower limit is not reached, the viscosity is too low and appearance defects such as familiarity and unevenness occur. Outside this range, the paint stability is reduced.

  Production of the coating composition used in the present invention is not particularly limited, including those described later, and those skilled in the art such as kneading and dispersing a composition such as a pigment using an SG mill, a kneader, or a roll. All methods well known in the art can be used.

Clear coating In the method for forming a laminated coating of the present invention, a clear coating is used to form a clear coating. As this clear paint, a solvent-type clear paint containing a film-forming resin and a curing agent can be used. The film-forming resin is not particularly limited, and an acrylic resin, a polyester resin, an epoxy resin, a urethane resin, and the like can be used. These include a curing agent such as an amino resin and / or a blocked isocyanate resin. Used in combination. From the viewpoint of transparency or acid etching resistance, it is preferable to use an acrylic resin and / or a combination of a polyester resin and an amino resin, or an acrylic resin and / or a polyester resin having a carboxylic acid / epoxy curing system.

  Solid content at the time of application | coating of the said clear coating is 30 to 70 weight%, Preferably it is 35 to 65 weight%.

  In addition, the clear paint usually contains the viscosity control agent described in the above-mentioned metallic base paint in order to prevent familiarity, inversion, or sagging between layers because it is applied in an uncured state after the base paint is applied. It is preferable to do. The addition amount of the viscosity control agent is 0.01 to 10 parts by weight, preferably 0.02 to 8 parts by weight, more preferably 0.03 to 6 parts by weight based on 100 parts by weight of the resin solid content of the clear coating composition. Added in parts by weight. If the amount of the viscosity control agent exceeds the upper limit, the appearance deteriorates, and if the amount is lower than the lower limit, the viscosity control effect cannot be obtained, which causes problems such as sagging during coating.

The clear paint used in the present invention may be any of the above solvent type, aqueous type (water-soluble, water-dispersible, emulsion), non-water-dispersed type, and powder type, and if necessary, a curing catalyst, surface A preparation agent or the like can be used.

A method of forming a coating film article to be coated <br/> present invention, various coating objects such as metal, plastic, foam and the like, in particular metal surfaces, and may be advantageously used in casting, a cationic electrodeposition coating can It can be particularly suitably used for a simple metal product.

Examples of the metal products include iron, copper, aluminum, tin, zinc, and the like, and alloys and castings containing these metals. Specific examples include automobile bodies and parts such as passenger cars, trucks, motorcycles, and buses. These metals are particularly preferably those subjected to chemical conversion treatment with phosphate, chromate or the like in advance.

Forming method of laminated coating film In the coating film forming method of the present invention, an undercoat film such as an electrodeposition film is formed on an object to be coated, and then an intermediate coat film is formed with an intermediate coat and cured. Thereafter, in the method of forming a laminated coating film in which a metallic base coating film is formed with the solvent-based metallic base coating composition of the present invention, and a clear coating film is formed with a clear coating by wet-on-wet, and simultaneously baked and cured, The metallic base coating composition contains a urea-modified acrylic resin (A), a urethane-modified polyester resin (B), a curing agent (C), and a glitter pigment (D).

As the electrodeposition paint for forming the undercoat film, a cation type and an anion type can be used. However, the cation type electrodeposition paint composition provides a multilayer coating film excellent in anticorrosion.

The intermediate coating composition for forming the intermediate coating film contains various organic and inorganic color pigments and extender pigments, a film-forming resin, a curing agent, and the like. The intermediate coating film can conceal the base, ensure surface smoothness after the top coating (improve the appearance), and impart coating film properties (impact resistance, chipping resistance, etc.).

Examples of the color pigment used for the intermediate coating include organic pigments and inorganic pigments described in the above-mentioned solvent-type metallic base coating composition. Further, extender pigments, and flat pigments such as aluminum powder and mica powder may be used in combination.

As a standard, a gray-based intermediate coating material having carbon black and titanium dioxide as main pigments is used. Furthermore, a so-called color intermediate coating composition in which a set gray in which the top coating color is combined with lightness, hue, or the like or various coloring pigments are combined can also be used.

The film-forming resin used for the intermediate coating is not particularly limited, and acrylic resin, polyester resin, alkyd resin, epoxy resin, urethane resin, and the like can be used. Alternatively, it is used in combination with a curing agent such as a blocked isocyanate resin. From the viewpoint of pigment dispersibility or workability, a combination of an alkyd resin and / or a polyester resin and an amino resin is preferable.

The intermediate coating film can be cured at a curing temperature of 100 to 180 ° C., preferably 120 to 160 ° C., to obtain a cured coating film having a high degree of crosslinking. If the upper limit is exceeded, the coating film becomes hard and brittle, and if it is less than the lower limit, curing is not sufficient. The curing time varies depending on the curing temperature, but 120 to 160 ° C. and 10 to 30 minutes are appropriate.

When the solvent-based metallic base coating composition of the present invention is applied to an automobile body or the like, air electrostatic spray coating, or so-called “μμ (micro micro) bell”, “μ (micro ) Bell ”or“ Metal Bell ”or the like, and multi-stage coating using a rotary atomizing electrostatic coating machine, preferably two stages. The method of the present invention can be suitably used for these coating methods.

  Although the dry film thickness of a metallic base coating film changes with desired uses, it is 5-20 micrometers in many cases, Preferably it is 6-18 micrometers. If the upper limit is exceeded, defects such as unevenness, sagging, and pinholes will occur during painting, and if it falls below the lower limit, the scale, unevenness, and appearance will deteriorate.

In the coating film forming method of the present invention, the clear coating film that is applied after forming the metallic base coating film smoothes and protects unevenness, flickering, and the like caused by the bright pigment contained in the metallic base coating film. Formed for. Specifically, as a coating method, it is preferable to form a coating film by the above-described rotary atomizing electrostatic coater such as μμ bell or μbell.

Although the dry film thickness of the clear coating film formed with the said clear coating material changes with desired uses, it is 10-80 micrometers in many cases, More preferably, it is about 20-60 micrometers. If the upper limit is exceeded, sharpness may deteriorate, or defects such as unevenness, pinholes, or flow may occur during painting. If the lower limit is exceeded, the substrate cannot be concealed and film breakage occurs.

After the clear coating film is applied, a cured coating film having a high degree of crosslinking can be obtained by setting the curing temperature for curing the metallic coating film to 80 to 180 ° C, preferably 120 to 160 ° C. If the upper limit is exceeded, the coating film becomes hard and brittle, and if it is less than the lower limit, curing is not sufficient. The curing time varies depending on the curing temperature, but it is suitably from 120 to 160 ° C. for 10 to 30 minutes.

The film thickness of the laminated coating film formed in the present invention is often 30 to 300 μm, and preferably 50 to 250 μm. When the upper limit is exceeded, film physical properties such as a cooling cycle decrease, and when the lower limit is exceeded, the strength of the film itself decreases.

  EXAMPLES Hereinafter, although a specific Example is given and this invention is demonstrated in detail, this invention is not limited by a following example. In the following description, “part” means “part by weight”.

(Example 1)
Production Example 1
Manufacture of urethane-modified polyester resin A 2 L reaction vessel equipped with a nitrogen introducing tube, a stirrer, a temperature controller, a dropping funnel and a cooling tube equipped with a decanter, 334 parts of isophthalic acid, 311 parts of hexahydrophthalic acid, 57 parts of ethylene glycol Then, 105 parts of trimethylolpropane and 289 parts of neopentylglycol were charged, and when the raw material was dissolved and stirred by heating, 0.2 part of dibutyltin oxide was added, stirring was started, and the reaction layer temperature was set at 180 ° C. The temperature was gradually raised to 220 ° C. over 3 hours. The resulting condensed water was distilled out of the system. When the temperature reached 220 ° C., the temperature was kept for 1 hour, 20 parts of xylene was gradually added into the reaction layer, and the condensation reaction proceeded in the presence of a solvent. When the resin acid value reached 8 mgKOH / g, it was cooled to 100 ° C., and 10 parts of hexamethylene diisocyanate was gradually added over 30 minutes. Further, after holding for 1 hour, 344 parts of xylene, 43 parts of butyl acetate and 43 parts of n-butanol were added, and urethane having a solid content of 70%, a number average molecular weight of 1800, a weight average molecular weight of 10,000, an acid value of 6 mgKOH / g, and a hydroxyl value of 100 A modified polyester resin was obtained.

Production Example 2
Production of acrylic resin 50 parts of xylene and 14 parts of n-butanol were placed in a 1 L reaction vessel equipped with a nitrogen introducing tube, a stirrer, a temperature controller, a dropping funnel and a cooling tube equipped with a decanter, and the temperature was adjusted to 110 ° C. . Next, 5 parts of styrene, 35.3 parts of ethyl acrylate, 41.1 parts of butyl methacrylate, 15.5 parts of hydroxyethyl acrylate, 3.1 parts of methacrylic acid, and 4.0 parts of t-butylperoxy 2-ethylhexanoate Was added dropwise over 3 hours. Next, a solution consisting of 1.0 part of t-butylperoxy 2-ethylhexanoate and 6 parts of xylene was added dropwise over 30 minutes, and the mixture was further maintained at 110 ° C. for 1 hour. An acrylic resin having a solid content of 60%, an acid value of 20 mgKOH / g, a hydroxyl value of 75, and a number average molecular weight of 5000 was obtained.

Production Example 3
In a reactor equipped with a stirring apparatus for producing a melamine co-condensed acrylic resin, 166.7 parts of the acrylic resin of Production Example 2 and Uban 20N-60 (Butylated melamine manufactured by Mitsui Chemicals, solid content 60%) 16.7 The melamine co-condensed acrylic resin co-condensed was obtained by charging the part and stirring at 80 ° C. for 1 hour.

Production Example 4
Production of solvent-type metallic base paint 1 AS-9606 (Urea modified acrylic resin manufactured by Mitsubishi Rayon Co., Ltd., urea modified amount 6.5%, acid value 12 mgKOH / g, hydroxyl value 70, weight average molecular weight) 7000, Tg 16 ° C.) 75 parts, 14.3 parts of urethane-modified polyester of Production Example 1 and 2.9 parts of cyanine blue G-314 (Sanyo Dye Company Blue Pigment) in advance to 25 parts of Melamine Co-Condensed Acrylic Resin of Production Example 3 In addition, 33.9 parts of pigment dispersion paste obtained by dispersing 6.0 parts of Varifine BF-40 (barium sulfate pigment manufactured by Sakai Chemical Co., Ltd.) so that each particle size is 5 μm or less, Uban 20N60 (Mitsui Chemicals) 50 parts of butylated melamine resin, solid content 60%, aluminum paste 7640NS (aluminum pigment manufactured by Toyo Aluminum Co., Ltd.) Weigh 65%) 17.8 parts, was stirred at tabletop stirrer was adjusted in light blue solvent-borne metallic base paint 1 (PWC17.0%).

Forming method of multilayer coating Cationic electrodeposition paint "V-50" (manufactured by Nippon Paint Co., Ltd.) is cured on a 30cm long, 40cm wide, 0.8mm thick steel plate that has been subjected to zinc phosphate conversion treatment. Electrodeposited to a film thickness of about 20 μm, cured at 160 ° C. for 30 minutes, and then cured with a gray intermediate coating “Orga P-2 Primer” (manufactured by Nippon Paint Co., Ltd.) to a cured film thickness of about 25 μm. Air-spray coating was performed, and the mixture was allowed to stand at room temperature for 3 minutes and then heated and cured at 140 ° C. for 30 minutes to obtain an article to be coated.

The solvent-type metallic base paint 1 produced previously was diluted with a thinner diluted with 10 parts of Solvesso 150 (a hydrocarbon solvent manufactured by Exxon Petroleum), 40 parts of ethyl acetate, 40 parts of toluene and 10 parts of butyl acetate. The dilution was adjusted to 12.5 seconds / 20 ° C. with a 4 Ford cup.

The above-mentioned substrate board degreased with a solvent is set up vertically, and the above-mentioned metallic base paint is made of “Metal Bell” (rotary atomization type static product manufactured by Lansburg Co., Ltd.) in two stages at intervals of 2 minutes so that the dry film thickness becomes 15 μm. It was painted with an electric coating machine. It was left to stand at room temperature for 4 minutes, and the metallic base coating film was created.

Next, in advance, no. A clear paint “McFlow O-1800” (manufactured by Nippon Paint Co., Ltd.) diluted to 25 seconds / 20 ° C. with a 4 Ford cup is wet-on-wet so that the dry paint film becomes 35 μm. Painted by recoating. Then, after standing at room temperature for 7 minutes in a vertical state, the film was baked in a dryer at 140 ° C. for 30 minutes in the vertical state. A metallic coating film was obtained by 2 coats and 1 bake.

The obtained metallic coating film was evaluated according to the following evaluation method.
<Dispersion stability>
In order to evaluate the dispersion stability (paint circulation property) of the organic coloring pigment that occurs during the circulation of the paint, 4 L of a metallic base paint 1 adjusted to the paint viscosity was prepared. A plunger pump “PPS-102” manufactured by Anest Iwata with a compression ratio of 1: 3 was used and circulated at an air pressure of 0.5 kg / cm 2 for 24 hours. Next, the paint after this circulation was spray-coated by the same method as the paint before the circulation to create a metallic coating film.
After the obtained coating film was cured, the color difference (ΔE) was measured with a color difference meter “CR-200” manufactured by Minolta Co., Ltd. using the coating film prepared using the paint before circulation as a standard. The smaller the value, the better the storage stability (hue stability) of the paint.
<Adhesion>
Adhesion of the obtained coated plate was performed as follows using evaluation of chipping resistance. Using a gravel tester tester (manufactured by Suga Test Instruments Co., Ltd.), 300 specimens of No. 7 crushed stone cooled to −30 ° C. from a distance of 35 cm to an air pressure of 3.0 kgf / cm 2 and 45 ° to the coating film Collided at an angle. After washing and drying, a peel test was performed using an industrial gum tape manufactured by Nichiban Co., Ltd., and then the degree of peeling of the coating film was visually observed to evaluate adhesion. Evaluation was made in 5 stages.
1: Peeling scratches on the entire surface, peeling from the substrate 2: Peeling scratches on the entire surface, no peeling from the substrate 3: Peeling scratches on the entire surface, peeling from the substrate 4: Partial peeling scratches, no peeling from the substrate 5: Table 1 shows the evaluation results with almost no peeling.

[Table 1]

Examples 2 and 3
The melamine co-condensed acrylic resin used in Example 1 so as to have the resin component blending amounts shown in Table 1 were 10.0 parts of Solsperse 232550 (basic pigment dispersant manufactured by Avicia) and Disperbyk 182 (base manufactured by BYK). Example of using solvent-type metallic base paints 2 and 3 produced in the same manner as solvent-type metallic base paint 1 except that a pigment paste in which a pigment is dispersed in advance was blended instead of 5.0 parts. A metallic coating film was prepared in the same manner as in Example 1 and evaluated in the same manner.

Comparative Example 1
Similarly, the melamine co-condensed acrylic resin used in the solvent-type metallic base paint used in Example 1 is replaced with the acrylic resin of Production Example 2, so that the resin component blending amounts shown in Table 1 above are obtained. A solvent-type metallic base coating 4 was prepared, and a metallic coating film was prepared in the same manner as in Example 1 and evaluated in the same manner.

Each of the light blue based solvent-based metallic base paints obtained in the above examples is excellent in hue stability, and the obtained metallic coating film is excellent in adhesion under severe conditions such as application of chipping evaluation. In addition, it was possible to feel a fine radiance that was not particularly obtained with a conventional medium-color paint such that the brilliant pigment was uniformly dispersed.

Claims (4)

  Solvent-type metallic base containing urea-modified acrylic resin (A), urethane-modified polyester resin (B), curing agent (C), glitter pigment (D), color pigment (E), and color pigment dispersion aid (F) A solvent-type metallic base, characterized in that the solid content weight ratio of the urea-modified acrylic resin (A) and the urethane-modified polyester resin (B) is 60/40 to 95/5. Paint composition.   2. The solvent-based metallic base coating composition according to claim 1, wherein the coloring pigment dispersing aid is selected from melamine co-condensed acrylic resins, basic pigment dispersing agents and mixtures thereof.   3. The solvent-type metallic base coating composition according to claim 1, wherein the curing agent (C) is a melamine resin. In the method of forming a laminated coating film in which a solvent-based metallic base coating composition and a clear coating are sequentially formed on a substrate by wet-on-wetting, the solvent-based metallic base coating composition includes a urea-modified acrylic resin (A) and a urethane-modified coating. A laminate characterized by being a solvent-type metallic base coating composition containing a polyester resin (B), a curing agent (C), a glitter pigment (D), a color pigment (E), and a color pigment dispersion aid (F) Method for forming a coating film.