JP5547450B2 - Colored paint composition - Google Patents

Description

  The present invention relates to a colored coating composition, a coating film forming method using the same, and a coating film repairing method.

  A white composite film consisting of an electrodeposition coating film, intermediate coating film, white base coat film, white pearl-like or silver pearl-like glitter base coat film, and clear coat film is applied to an object such as an automobile outer plate. Forming a layer coating film is known (for example, Patent Document 1).

  In such a white multi-layer coating film, light passes through the clear coat film and the glitter base coat film, and thus the color tone of the white base coat film and the design of the glitter base coat film are combined. A coating film having an excellent appearance with a white pearl tone or silver pearl tone luxury can be formed.

  Recently, as a paint for forming the white base coat film, a study has been conducted to further improve the design by using a paint containing other color pigments in addition to a titanium dioxide pigment which is a white pigment. It is. In this case, the color pigment used is generally a pigment having a relatively small particle diameter and excellent coloring power. This is the same when a black pigment is used as the colored pigment. In the white base coat film, it is common to use a relatively small black pigment having a particle size of about 20 to 25 μm. It was.

  In addition, as a method for forming the white multi-layer coating film, generally, the electrodeposition coating material and the intermediate coating material are heated and cured to form the electrodeposition coating material and the intermediate coating film, and then the obtained intermediate coating material is applied. A white base coat paint, a glitter base coat paint and a clear coat paint were sequentially applied on the film, and then a three-coat one-bake (3C1B) method in which these three layers of paint were simultaneously cured and a white base coat paint were applied. Thereafter, the white base coat paint is cured, and then the glitter base coat paint and the clear coat paint are sequentially applied, and then these two layers of paint are simultaneously cured, and a 3 coat 2 bake (3C2B) system is used. . However, in both the 3-coat 1-bake method and the 3-coat 2-bake method, each coating surface during the coating process, for example, during coating, during transfer to the next process, during heat curing of the coating film, etc. The finished appearance may be deteriorated due to dust adhering to the surface or dents on the coating film.

  In general, as a method for repairing these defective portions, in the 3-coat 1-bake method, generally, the portion is ground and removed until the electrodeposition coating film is exposed, and a white base coat coating film or a glittering base coat coating film is applied to that section. Forming a three-layer coating film composed of a film and a clearcoat coating film is performed (for example, Patent Document 2).

  On the other hand, in the 3-coat 2-bake method, there is a curing step after the white base coat paint is applied, and thereby a cured coating film of the white base coat is formed, so when a defective part is found in the cured coating film, The defective portion is ground and removed to such an extent that the lower layer coating film cannot be seen through, and subsequently the defective portion is repaired by forming a two-layer coating film composed of a glittering base coat paint and a clear coat paint. It is.

  The repair method in the 3-coat 2-bake method does not require the white base coat paint to be applied again after grinding and removing the defective portion. Compared to the repair method in the 3-coat 1-bake method, the repair paint is used. It has the advantage that it can be repaired with a small amount and a small number of man-hours.

  However, in the 3-coat 2-bake method, when the white base coat paint containing a black pigment having a relatively small particle diameter is used, the color of the repaired portion where the white base coat paint is ground and removed is lower layer. Even when the grinding removal was performed to such an extent that the coating film could not be seen through, the color of the non-repaired portion was sometimes different. In this case, the color difference between the repaired part and the non-repaired part generated in the white base coat film is visually recognized through the glitter base coat film and the clear coat film, and as a result, the resulting white multilayer coat film Caused a decrease in the appearance of, and was a problem.

JP-A-8-164358 JP 2002-205007 A

  An object of the present invention is to form a white multi-layer coating film by sequentially applying a white base coat paint, a glitter base coat paint and a clear coat paint on an object to be coated. An object of the present invention is to provide a colored coating composition excellent in repairability, which does not cause a difference in color between a repaired portion and a non-repaired portion even if the white base coat film is ground and removed for repair.

  As a result of diligent research, the present inventors have found that the above object can be achieved when a colored paint composition containing a specific pigment is used as the white base coat paint, and the present invention has been completed. It was.

That is, the present invention provides the following colored coating composition, and a coating film forming method and a coating film repair method using the same.
1. The following steps (1) to (4),
Step (1): A step of applying a white base coat paint (X) on an object to be coated and curing to form a white base coat cured coating film having L * of 70 or more,
Step (2): a step of coating the white basecoat cured coating film formed in Step (1) with a glittering basecoat coating (Y) to form a glittering basecoat coating film,
Step (3): a step of applying a clear coat paint (Z) on the uncured glitter base coat film formed in step (2) to form a clear coat film, and step (4): step In the white multi-layer coating film forming method in which the uncured base coat film formed in (2) and the uncured clear coat film formed in step (3) are simultaneously heated and cured, A colored coating composition for use as a base coat coating (X), which is a film-forming resin (A), a curing agent (B), and a titanium dioxide pigment (C) having an average primary particle size in the range of 200 to 350 nm. ) And a black pigment (D), and the blending ratio of the film-forming resin (A), the curing agent (B), the titanium dioxide pigment (C), and the black pigment (D) is the film-forming resin (A) and 100 parts by mass of the total amount of the curing agent (B) As a reference, the film-forming resin (A) is 30 to 95 parts by mass, the curing agent (B) is 5 to 70 parts by mass, the titanium dioxide pigment (C) is 15 to 160 parts by mass, and the black pigment (D) is 0.00. The black pigment (D1) in the range of 01 to 5 parts by mass and the black pigment (D) having an average primary particle diameter in the range of 30 to 300 nm is based on the total amount of the black pigment (D). 40% by mass or more of a colored coating composition,
2. The following steps (1) to (4),
Step (1): A step of applying a white base coat paint (X) on an object to be coated and curing to form a white base coat cured coating film having L ^* of 70 or more,
Step (2): a step of coating the white basecoat cured coating film formed in Step (1) with a glittering basecoat coating (Y) to form a glittering basecoat coating film,
Step (3): a step of applying a clear coat paint (Z) on the uncured glitter base coat film formed in step (2) to form a clear coat film, and step (4): step In the white multi-layer coating film forming method in which the uncured base coat film formed in (2) and the uncured clear coat film formed in step (3) are simultaneously heated and cured, The base coat paint (X) contains a film-forming resin (A), a curing agent (B), a titanium dioxide pigment (C) and a black pigment (D) whose average primary particle diameter is in the range of 200 to 350 nm , The blending ratio of the film-forming resin (A), the curing agent (B), the titanium dioxide pigment (C) and the black pigment (D) is 100 parts by mass of the total amount of the film-forming resin (A) and the curing agent (B). As a standard, the film-forming resin (A) is 30 95 parts by weight, 5 to 70 parts by weight curing agent (B), is in the range from 15 to 160 parts by weight of titanium dioxide pigment (C) is a black pigment (D) is 0.01 to 5 parts by weight, and black The pigment (D) is a colored coating composition containing 40% by mass or more of a black pigment (D1) having an average primary particle diameter in the range of 30 to 300 nm, based on the total amount of the black pigment (D). A method for forming a white multi-layer coating film, comprising:
3. The method for forming a white multi-layer coating film according to Item 2 , wherein the article to be coated is a vehicle body on which an undercoat film and / or an intermediate coat film is formed.
4. An article coated by the method for forming a white multi-layer coating film as described in 2 or 3 above.
5 . The following steps (I) to (V),
Step (I): A step of applying a white base coat paint (X) on an object to be coated and curing to form a white base coat cured coating film having L ^* of 70 or more,
Process (II): Grinding and removing the defective part generated in the white base coat cured coating film formed in process (I) within a range where the brightness difference ΔL ^* between the ground part and the non-ground part is 0.5 or less. The process of
Step (III): a step of coating the white basecoat cured coating film formed in steps (I) and (II) with a glittering basecoat coating (Y) to form a glittering basecoat coating film,
Step (IV): a step of applying a clear coat paint (Z) on the uncured glitter base coat film formed in step (III) to form a clear coat film, and step (V): step In the repair method of the white multi-layer coating film in which the uncured base coat film formed in (III) and the uncured clear coat film formed in step (IV) are heated and cured simultaneously, The base coat paint (X) contains a film-forming resin (A), a curing agent (B), a titanium dioxide pigment (C) and a black pigment (D) whose average primary particle diameter is in the range of 200 to 350 nm. The blending ratio of the film-forming resin (A), the curing agent (B), the titanium dioxide pigment (C), and the black pigment (D) is 100 mass of the total amount of the film-forming resin (A) and the curing agent (B). Film-forming tree 30-95 parts by mass of (A), 5-70 parts by mass of curing agent (B), 15-160 parts by mass of titanium dioxide pigment (C), and 0.01-5 parts by mass of black pigment (D). And the black pigment (D) contains 40% by mass or more of the black pigment (D1) having an average primary particle diameter in the range of 30 to 300 nm based on the total amount of the black pigment (D). A method for repairing a white multilayer coating film, which is a colored coating composition.

  When a white base coat paint, a glitter base coat paint, and a clear coat paint are sequentially applied on an object to form a white multi-layer coating film, the colored paint composition of the present invention is used as the white base coat paint. By using it, even if the white base coat film is ground and removed to repair defective parts that occurred in the painting process, the color difference between the repaired part and the non-repaired part does not occur, and the paint film has excellent repairability. Can be formed.

  Hereinafter, the colored coating composition of the present invention will be described in detail.

The colored coating composition of the present invention (hereinafter sometimes abbreviated as “present coating”) is prepared by the following steps (1) to (4),
Step (1): A step of applying a white base coat paint (X) on an object to be coated and curing to form a white base coat cured coating film having L ^* of 70 or more,
Step (2): a step of coating the white basecoat cured coating film formed in Step (1) with a glittering basecoat coating (Y) to form a glittering basecoat coating film,
Step (3): a step of applying a clear coat paint (Z) on the uncured glitter base coat film formed in step (2) to form a clear coat film, and step (4): step In the white multi-layer coating film forming method in which the uncured base coat film formed in (2) and the uncured clear coat film formed in step (3) are simultaneously heated and cured, A colored paint composition for use as a base coat paint (X), comprising a film-forming resin (A), a curing agent (B), a titanium dioxide pigment (C) and a black pigment (D), and black Colored paint characterized in that the pigment (D) contains a black pigment (D1) having an average primary particle diameter in the range of 30 to 500 nm in an amount of 40% by mass or more based on the total amount of the black pigment (D). It is a composition.

  Hereinafter, the white type multilayer coating film forming method using the colored coating composition of the present invention will be described in more detail.

Process (1)
In this step, a white base coat paint (X) is applied on the object to be coated and cured to form a white base coat cured coating film having L ^* of 70 or more. Especially, it is suitable that L ^* is in the range of 75 to 95, preferably 80 to 90, from the viewpoint of excellent design properties of the resulting white multi-layer coating film.

Here, L ^* is a value in the L ^* a ^* b ^* color system defined by JIS Z 8729 (1994). In the L ^* a ^* b ^* color system, “brightness” is expressed by L ^* as the degree of brightness that can be compared regardless of hue, and indicates that the color becomes brighter as L ^* increases and becomes darker as it decreases. . In addition, “hue” which varies depending on each color is indicated by a ^* and b ^* values, a ^* indicates red (+) to green (−) direction, and b ^* indicates yellow (+) to blue (−) direction, In each direction, the color becomes brighter as the absolute value increases, and the color becomes dull as it approaches 0. This makes it possible to digitize one color using L ^* , a ^* , and b ^* . In the white base coat cured coating film, {(a ^* ) ² + (b ^* ) ² } ^1/2 is 10 or less, preferably 5 or less, more preferably 3 or less.

In the present invention, L ^* , a ^* , and b ^* of the white base coat film are irradiated with light from an angle of 45 ° with respect to an axis perpendicular to the paint film surface, and the reflected light is perpendicular to the paint film surface. This is the value when the color of the direction light is measured. Specifically, the L ^* , a ^* , and b ^* are measured, for example, using a multi-angle spectrocolorimeter “CM-512m3” (manufactured by Konica Minolta Co., Ltd.) under measurement conditions with an illumination incident angle of 45 °. It can be obtained by coloring.

In this step, by forming a white base coat cured coating film having L ^* of 70 or more, a white multilayer coating film having excellent design properties can be obtained.

Coating material The coating material to which the white base coat paint (X) can be applied according to the present invention is not particularly limited. For example, an outer plate portion of an automobile body such as a passenger car, a truck, a motorcycle, a bus; Parts: Examples of the outer plate of a home electric product such as a mobile phone or an audio device. Of these, the outer plate portion of the automobile body and the automobile parts are preferable.

  The material of these objects to be coated is not particularly limited. For example, iron, aluminum, brass, copper, tinplate, stainless steel, galvanized steel, alloyed zinc (Zn-Al, Zn-Ni, Zn) -Fe, etc.) Metal materials such as plated steel; resins such as polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, epoxy resin, etc. Examples include various plastic materials such as FRP; inorganic materials such as glass, cement, and concrete; wood; fiber materials such as paper and cloth. Of these, metal materials and plastic materials are preferred.

  The object to be coated may be one in which a surface treatment such as a phosphate treatment, a chromate treatment, or a complex oxide treatment is performed on a metal surface of the metal material or a vehicle body formed from the metal material. Further, the object to be coated may be one in which an undercoat film and / or an intermediate coat film such as various electrodeposition paints are formed on the metal base material, the vehicle body or the like.

White base coat paint (X)
In the present invention, the white base coat paint (X) contains a film-forming resin (A), a curing agent (B), a titanium dioxide pigment (C) and a black pigment (D), and the black pigment (D) A colored coating composition containing 40% by mass or more of the black pigment (D1) having an average primary particle diameter in the range of 30 to 500 nm based on the total amount of the black pigment (D) is used.

Film-forming resin (A)
As the film-forming resin (A), a film-forming resin known per se that has been conventionally used in paints can be used. As a kind of resin, an acrylic resin, a polyester resin, an alkyd resin, a polyurethane resin etc. are mentioned, for example. The film-forming resin (A) usually has a crosslinkable functional group such as a hydroxyl group, a carboxyl group, or an epoxy group.

  The film-forming resin (A) is preferably a hydroxyl group-containing polyester resin (A1) and / or a hydroxyl group-containing acrylic resin (A2), and more preferably a hydroxyl group-containing polyester resin (A1). .

  When the film-forming resin (A) has a hydroxyl group, the hydroxyl value is preferably 1 to 300 mgKOH / g, more preferably 2 to 250 mgKOH / g, and 3 to 180 mgKOH / g. Is more preferable. When the film-forming resin (A) has an acid group such as a carboxyl group, the acid value is preferably 1 to 200 mgKOH / g, more preferably 2 to 150 mgKOH / g, and 3 to 100 mgKOH. More preferably, it is / g.

Hydroxyl-containing polyester resin (A1)
In the colored coating composition of the present invention, the smoothness of the resulting coating film can be improved by using the hydroxyl group-containing polyester resin (A1) as the film-forming resin (A).

  The hydroxyl group-containing polyester resin (A1) can be usually produced by an esterification reaction or an ester exchange reaction between an acid component and an alcohol component.

  As said acid component, the compound normally used as an acid component can be used at the time of manufacture of a polyester resin. Examples of the acid component include an aliphatic polybasic acid, an alicyclic polybasic acid, an aromatic polybasic acid, and the like.

  The aliphatic polybasic acid is generally an aliphatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aliphatic compound, and an esterified product of the aliphatic compound. Examples of the aliphatic polybasic acid include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, octadecanedioic acid, and citric acid. Aliphatic polyvalent carboxylic acid; anhydride of the aliphatic polyvalent carboxylic acid; esterified product of lower alkyl having about 1 to 4 carbon atoms of the aliphatic polyvalent carboxylic acid. The above aliphatic polybasic acids can be used alone or in combination of two or more.

  As the aliphatic polybasic acid, it is particularly preferable to use adipic acid and / or adipic anhydride from the viewpoint of the smoothness of the resulting coating film.

  The alicyclic polybasic acid is generally a compound having one or more alicyclic structures and two or more carboxyl groups in one molecule, an acid anhydride of the compound, and an esterified product of the compound. The alicyclic structure is mainly a 4- to 6-membered ring structure. Examples of the alicyclic polybasic acid include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 3-methyl- Alicyclic polycarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid; An anhydride of an alicyclic polyvalent carboxylic acid; an esterified product of a lower alkyl having about 1 to 4 carbon atoms of the alicyclic polyvalent carboxylic acid. The said alicyclic polybasic acid can be used individually or in combination of 2 or more types.

  As said alicyclic polybasic acid, from a smoothness viewpoint of the coating film obtained, 1, 2- cyclohexane dicarboxylic acid, 1, 2- cyclohexane dicarboxylic acid anhydride, 1, 3- cyclohexane dicarboxylic acid, 1, 4 -Cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic anhydride are preferably used, among which 1,2-cyclohexanedicarboxylic acid and / or 1,2 -More preferred is the use of cyclohexanedicarboxylic anhydride.

  The aromatic polybasic acid is generally an aromatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aromatic compound, and an esterified product of the aromatic compound, for example, phthalic acid , Isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, trimellitic acid, pyromellitic acid and other aromatic polycarboxylic acids; anhydrides of the aromatic polycarboxylic acids; aromatics Examples thereof include esterified products of lower alkyl having about 1 to 4 carbon atoms of polyvalent carboxylic acid. The aromatic polybasic acids can be used alone or in combination of two or more.

  As the aromatic polybasic acid, it is preferable to use phthalic acid, phthalic anhydride, isophthalic acid, trimellitic acid, or trimellitic anhydride.

  Moreover, acid components other than the said aliphatic polybasic acid, alicyclic polybasic acid, and aromatic polybasic acid can also be used. Such acid component is not particularly limited, for example, coconut oil fatty acid, cottonseed oil fatty acid, hemp seed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, Fatty acids such as castor oil fatty acid, dehydrated castor oil fatty acid, safflower oil fatty acid; lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, p-tert-butylbenzoic acid, cyclohexane Examples thereof include monocarboxylic acids such as acid and 10-phenyloctadecanoic acid; hydroxycarboxylic acids such as lactic acid, 3-hydroxybutanoic acid, and 3-hydroxy-4-ethoxybenzoic acid. These acid components can be used alone or in combination of two or more.

  As said alcohol component, the polyhydric alcohol which has a 2 or more hydroxyl group in 1 molecule can be used conveniently. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3 -Butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentane 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, water Dihydric alcohols such as hydrogenated bisphenol A and hydrogenated bisphenol F; polylactone diols obtained by adding lactones such as ε-caprolactone to these dihydric alcohols; ester diols such as bis (hydroxyethyl) terephthalate; alkylenes of bisphenol A Oxide adducts, polyether diols such as polyethylene glycol, polypropylene glycol, polybutylene glycol; glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6- Trivalent or higher alcohols such as hexanetriol, pentaerythritol, dipentaerythritol, tris (2-hydroxyethyl) isocyanuric acid, sorbitol, mannitol; lactones such as ε-caprolactone are added to these trivalent or higher alcohols And polylactone polyols.

  Moreover, alcohol components other than the said polyhydric alcohol can also be used. The alcohol component is not particularly limited, and examples thereof include monoalcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, stearyl alcohol, and 2-phenoxyethanol; propylene oxide, butylene oxide, “Cardura E10” (trade name, HEXION Specialty) Examples include alcohol compounds obtained by reacting monoepoxy compounds such as Chemicals, Inc. (glycidyl esters of synthetic highly branched saturated fatty acids) and acids.

  The manufacturing method of a hydroxyl-containing polyester resin (A1) is not specifically limited, It can carry out in accordance with a normal method. For example, the acid component and the alcohol component are heated in a nitrogen stream at about 150 to 250 ° C. for about 5 to 10 hours, and a method of performing esterification reaction or transesterification reaction of the acid component and alcohol component is performed. A containing polyester resin can be produced.

  When the acid component and the alcohol component are esterified or transesterified, they may be added to the reaction vessel at one time, or one or both may be added in several portions. . First, after synthesizing a hydroxyl group-containing polyester resin, the resulting hydroxyl group-containing polyester resin may be reacted with an acid anhydride to be half-esterified to obtain a carboxyl group- and hydroxyl group-containing polyester resin. First, after synthesizing a carboxyl group-containing polyester resin, the alcohol component may be added to obtain a hydroxyl group-containing polyester resin.

  In the esterification or transesterification reaction, as a catalyst for promoting the reaction, dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, tetraisopropyl A catalyst known per se, such as titanate, can be used.

  The hydroxyl group-containing polyester resin (A1) can be modified with a fatty acid, a monoepoxy compound, a polyisocyanate compound or the like during or after the preparation of the resin.

  Examples of the fatty acid include coconut oil fatty acid, cottonseed oil fatty acid, hemp seed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor oil fatty acid, dehydrated castor Oil fatty acid, safflower oil fatty acid and the like can be mentioned, and as the above-mentioned monoepoxy compound, for example, “Cardura E10” (trade name, manufactured by HEXION Specialty Chemicals, glycidyl ester of synthetic highly branched saturated fatty acid) is preferably used. it can.

  Examples of the polyisocyanate compound include aliphatic diisocyanates such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, and methylcyclohexane-2. , 6-diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), alicyclic diisocyanates such as 1,3- (isocyanatomethyl) cyclohexane; aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate Organic polyisocyanates such as polyisocyanates having 3 or more valences such as lysine triisocyanate An adduct of each of these organic polyisocyanates with a polyhydric alcohol, a low molecular weight polyester resin, water, etc .; a cyclized polymer (for example, isocyanurate) of each of these organic polyisocyanates, a biuret type adduct Etc. These polyisocyanate compounds can be used alone or in combination of two or more.

  Further, as the hydroxyl group-containing polyester resin (A1), the total content of the aliphatic polybasic acid and the alicyclic polybasic acid in the raw acid component is selected from the viewpoint of excellent smoothness of the resulting coating film. What is 30-100 mol% on the basis of the total amount of a component is preferable, What is 40-97 mol% is more preferable, What is 50-80 mol% is still more preferable. In particular, the aliphatic polybasic acid is adipic acid and / or adipic anhydride, and the alicyclic polybasic acid is 1,2-cyclohexanedicarboxylic acid and / or 1,2-cyclohexanedicarboxylic anhydride. Preferably there is.

  The hydroxyl group-containing polyester resin (A1) has a hydroxyl value of 10 to 300 mgKOH / g, preferably 30 to 250 mgKOH / g, more preferably 50 to 180 mgKOH / g, and an acid value of 1 is preferable. It is suitable to be in the range of ˜200 mg KOH / g, preferably 2 to 100 mg KOH / g, more preferably 3 to 60 mg KOH / g. The number average molecular weight is 500 to 50,000, preferably 1,000 to 30,000, and more preferably 1,200 to 10,000.

  In addition, the number average molecular weight and the weight average molecular weight in the present specification are based on the number average molecular weight or the weight average molecular weight measured with a gel permeation chromatograph (manufactured by Tosoh Corporation, “HLC8120GPC”) based on the molecular weight of standard polystyrene. It is a converted value. In this measurement, four columns of “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL”, and “TSKgel G-2000HXL” (both trade names, manufactured by Tosoh Corporation) were used as columns. The measurement conditions of mobile phase tetrahydrofuran, measurement temperature 40 ° C., flow rate 1 mL / min, detector RI were used.

  The amount of the hydroxyl group-containing polyester resin (A1) is 5 to 95 parts by mass, preferably 15 to 85, based on a total of 100 parts by mass of the film-forming resin (A) and the curing agent (B) in the paint. It is suitable that it is in the range of 25 parts by mass, more preferably 25 to 75 parts by mass.

Hydroxyl group-containing acrylic resin (A2)
The hydroxyl group-containing acrylic resin (A2) is usually prepared by a method known per se, for example, an organic compound containing a hydroxyl group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer. It can be produced by copolymerization by a method such as a solution polymerization method in a solvent or an emulsion polymerization method in water.

  The hydroxyl group-containing polymerizable unsaturated monomer is a compound having at least one hydroxyl group and one polymerizable unsaturated bond in one molecule, such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( Monoesterified product of (meth) acrylic acid such as (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and a dihydric alcohol having 2 to 8 carbon atoms; the (meth) acrylic acid Ε-caprolactone modified product of monoesterified product of C 2 and C 8 dihydric alcohol; N-hydroxymethyl (meth) acrylamide; allyl alcohol, and further having a polyoxyethylene chain whose molecular terminal is a hydroxyl group (meta ) Acrylate and the like.

  In the present specification, “(meth) acrylate” means “acrylate or methacrylate”. “(Meth) acrylic acid” means “acrylic acid or methacrylic acid”. “(Meth) acryloyl” means “acryloyl or methacryloyl”. “(Meth) acrylamide” means “acrylamide or methacrylamide”.

  Moreover, the other polymerizable unsaturated monomer copolymerizable with the said hydroxyl-containing polymerizable unsaturated monomer can be suitably selected and used according to the characteristic desired for a hydroxyl-containing acrylic resin (A2). Specific examples of the monomer are listed in (i) to (xix). These can be used alone or in combination of two or more.

  (I) alkyl or cycloalkyl (meth) acrylate: for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) Acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) a Relate, cyclododecyl (meth) acrylate, tricyclodecanyl (meth) acrylate.

  (Ii) Polymerizable unsaturated monomer having an isobornyl group: isobornyl (meth) acrylate and the like.

  (Iii) Polymerizable unsaturated monomer having an adamantyl group: adamantyl (meth) acrylate and the like.

  (Iv) Polymerizable unsaturated monomer having a tricyclodecenyl group: tricyclodecenyl (meth) acrylate and the like.

  (V) Aromatic ring-containing polymerizable unsaturated monomers: benzyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene and the like.

  (Vi) Polymerizable unsaturated monomer having an alkoxysilyl group: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) Acryloyloxypropyltriethoxysilane and the like.

  (Vii) Polymerizable unsaturated monomer having a fluorinated alkyl group: perfluoroalkyl (meth) acrylate such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate; fluoroolefin and the like.

  (Viii) A polymerizable unsaturated monomer having a photopolymerizable functional group such as a maleimide group.

  (Ix) Vinyl compound: N-vinyl pyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate and the like.

  (X) Phosphoric acid group-containing polymerizable unsaturated monomer: 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, 2-methacryloyloxypropyl acid phosphate, and the like.

  (Xi) Carboxy group-containing polymerizable unsaturated monomer: (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate and the like.

  (Xii) Nitrogen-containing polymerizable unsaturated monomer: (meth) acrylonitrile, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylamino Propyl (meth) acrylamide, methylene bis (meth) acrylamide, ethylene bis (meth) acrylamide, 2- (methacryloyloxy) ethyltrimethylammonium chloride, adducts of glycidyl (meth) acrylate and amines.

  (Xiii) Polymerizable unsaturated monomers having two or more polymerizable unsaturated groups in one molecule: allyl (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and the like.

  (Xiv) Epoxy group-containing polymerizable unsaturated monomer: glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate 3,4-epoxycyclohexylpropyl (meth) acrylate, allyl glycidyl ether and the like.

  (Xv) (meth) acrylate having a polyoxyethylene chain whose molecular end is an alkoxy group.

  (Xvi) polymerizable unsaturated monomer having a sulfonic acid group: 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth) acrylate, allylsulfonic acid, 4-styrenesulfonic acid, etc .; sodium salt of these sulfonic acids And ammonium salts.

  (Xvii) polymerizable unsaturated monomer having an ultraviolet-absorbing functional group: 2-hydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2-hydroxy-4- (3-acryloyloxy-2-hydroxy) Propoxy) benzophenone, 2,2′-dihydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2,2′-dihydroxy-4- (3-acryloyloxy-2-hydroxypropoxy) benzophenone, 2- (2′-hydroxy-5′-methacryloyloxyethylphenyl) -2H-benzotriazole and the like.

  (Xviii) UV-stable polymerizable unsaturated monomer: 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloyloxy-2,2,6,6- Tetramethylpiperidine, 4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4- (meth) acryloylamino-2,2,6,6 -Tetramethylpiperidine, 1- (meth) acryloyl-4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6- Tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2, , 6-tetramethylpiperidine and the like.

  (Xix) polymerizable unsaturated monomer having a carbonyl group: acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrol, vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl methyl ketone) , Vinyl ethyl ketone, vinyl butyl ketone) and the like.

  In addition, as the hydroxyl group-containing acrylic resin (A2), as a part thereof, a so-called urethane-modified acrylic resin obtained by extending a polyisocyanate compound to a part of the hydroxyl group in the resin by a urethanization reaction to increase the molecular weight is used in combination. May be.

  The hydroxyl value of the hydroxyl group-containing acrylic resin (A2) is 1 to 200 mgKOH / g, preferably 2 to 150 mgKOH / g, more preferably 3 to 100 mgKOH / g, from the viewpoints of storage stability and water resistance of the resulting coating film. It is preferable to be within the range of g.

  The acid value of the hydroxyl group-containing acrylic resin (A2) is from 1 to 200 mgKOH / g, preferably from 2 to 150 mgKOH / g, more preferably from 3 to 100 mgKOH / g, from the viewpoint of water resistance of the resulting coating film. It is preferable to be within the range.

  The weight-average molecular weight of the hydroxyl group-containing acrylic resin (A2) is 1,000 to 500,000, preferably 2,000 to 300,000, more preferably 3,000 to 200,000. Is preferred.

  When this paint contains a hydroxyl group-containing acrylic resin (A2), the amount of the hydroxyl group-containing acrylic resin (A2) is 100 parts by mass in total of the film-forming resin (A) and the curing agent (B) in the paint. Is based on 2 to 95 parts by mass, preferably 5 to 85 parts by mass, and more preferably 10 to 75 parts by mass.

Curing agent (B)
The curing agent (B) is a compound that can cure the composition of the present invention by reacting with a crosslinkable functional group such as a hydroxyl group, a carboxyl group, and an epoxy group in the film-forming resin (A). Examples of the curing agent (B) include amino resins, polyisocyanate compounds, blocked polyisocyanate compounds, epoxy group-containing compounds, carboxyl group-containing compounds, carbodiimide group-containing compounds, and the like. Of these, amino resins, polyisocyanate compounds and blocked polyisocyanate compounds that can react with hydroxyl groups are preferred, and amino resins are particularly preferred. A hardening | curing agent (B) can be used individually or in combination of 2 or more types.

  As said amino resin, the partial methylolation amino resin obtained by reaction of an amino component and an aldehyde component, or a complete methylolation amino resin can be used. Examples of the amino component include melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, dicyandiamide and the like. Examples of the aldehyde component include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde.

  Moreover, what methylated the methylol group of the said methylolated amino resin partially or completely with suitable alcohol can also be used. Examples of the alcohol used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2-ethyl-1-butanol, and 2-ethyl-1. -Hexanol etc. are mentioned.

  As the amino resin, a melamine resin is preferable. In particular, methyl ether melamine resins in which methylol groups of partially or fully methylolated melamine resins are partially or completely etherified with methyl alcohol, methylol groups of partially or fully methylolated melamine resins are partially or completely with butyl alcohol. Preferred is a methyl-butyl mixed etherified melamine resin in which the methylol group of a partially or completely methylolated melamine resin is partially or completely etherified with methyl alcohol and butyl alcohol. Etherified melamine resins are more preferred.

  The melamine resin preferably has a weight average molecular weight of 400 to 6,000, more preferably 500 to 4,000, and still more preferably 600 to 3,000.

  A commercially available product can be used as the melamine resin. Examples of commercially available product names include “Cymel 202”, “Cymel 203”, “Cymel 204”, “Cymel 211”, “Cymel 238”, “Cymel 251”, “Cymel 303”, “Cymel 323”, “Cymel 324”, “Cymel 325”, “Cymel 327”, “Cymel 350”, “Cymel 385”, “Cymel 1156”, “Cymel 1158”, “Cymel 1116”, “Cymel 1130” , "Uban 120", "Uban 20HS", "Uban 20SE60", "Uban 2021", "Uban 2028", "Uban 28-60" (above, Mitsui Chemicals).

  When a melamine resin is used as the curing agent (B), sulfonic acids such as paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid; salts of these sulfonic acids with amine compounds; It can be used as a catalyst.

  The blocked polyisocyanate compound is a compound obtained by blocking an isocyanate group of a polyisocyanate compound having at least two isocyanate groups in one molecule with a blocking agent.

  Examples of the polyisocyanate compound having at least two isocyanate groups in one molecule include aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and lysine diisocyanate; hydrogenated xylylene diisocyanate, cyclohexylene Cycloaliphatic diisocyanates such as diisocyanate and isophorone diisocyanate; Aromatic diisocyanates such as tolylene diisocyanate, phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate; 2-isocyanato Ethyl-2,6-diisocyanatocaproate, 3-i Trivalent or higher organic polyisocyanate compounds such as cyanatomethyl-1,6-hexamethylene diisocyanate and 4-isocyanatomethyl-1,8-octamethylene diisocyanate (commonly known as triaminononane triisocyanate); 2 of these polyisocyanate compounds A polymer or a trimer (biuret, isocyanurate, etc.); a prepolymer obtained by subjecting these polyisocyanate compound and polyhydric alcohol, low molecular weight polyester resin or water to urethanization under an excess of isocyanate groups. .

  Examples of the blocking agent include phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; ε-caprolactam, δ-valero Lactams such as lactam, γ-butyrolactam, β-propiolactam; aliphatic alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene Glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether Ethers such as propylene glycol monomethyl ether and methoxymethanol; benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylol urea, methylol melamine, di Alcohols such as acetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate; oximes such as formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime; dimethyl malonate, malon Active methylenes such as diethyl acetate, ethyl acetoacetate, methyl acetoacetate, acetylacetone; butyl mercaptan, Mercaptans such as t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol; acetanilide, acetanisid, acetolide, acrylamide, methacrylamide, acetic acid amide, stearic acid amide Acid amides such as benzamide; imides such as succinimide, phthalic acid imide, and maleic acid imide; diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, butylphenyl Amines such as amines; Imidazoles such as imidazole and 2-ethylimidazole; urea, thiourea, ethyleneurea, ethylene Ureas such as lenthiourea and diphenylurea; Carbamates such as phenyl N-phenylcarbamate; Imines such as ethyleneimine and propyleneimine; Sulphites such as sodium bisulfite and potassium bisulfite; Azole compounds Etc. Examples of the azole compounds include pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3, Pyrazole or pyrazole derivatives such as 5-dimethylpyrazole and 3-methyl-5-phenylpyrazole; Imidazole or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole and 2-phenylimidazole; 2-methylimidazoline And imidazoline derivatives such as 2-phenylimidazoline.

  Among them, preferred blocking agents include oxime blocking agents, active methylene blocking agents, pyrazoles or pyrazole derivatives.

  In addition, as the blocking agent, hydroxycarboxylic acids having one or more hydroxyl groups and one or more carboxyl groups, such as hydroxypivalic acid and dimethylolpropionic acid, can be used. In particular, when the present paint is a water-based paint, a blocked polyisocyanate compound in which an isocyanate group is blocked using the hydroxycarboxylic acid and then the carboxyl group of the hydroxycarboxylic acid is neutralized to impart water dispersibility is suitable. Can be used.

  As said carbodiimide group containing compound, what made the carbon dioxide reaction of the isocyanate groups of the said polyisocyanate compound can be used, for example. A commercial item can be used as this carbodiimide group containing compound. Examples of commercially available product names include “Carbodilite SV-02”, “Carbodilite V-02”, “Carbodilite V-02-L2”, “Carbodilite V-04”, “Carbodilite E-01”, “Carbodilite E”. -02 "(all manufactured by Nisshinbo Co., Ltd.).

Titanium dioxide pigment (C)
The titanium dioxide pigment (C) used in the present paint is a white pigment, and can impart white color to the formed coating film.

  The titanium dioxide pigment (C) has an average primary particle diameter of 200 to 350 nm, preferably 220 to 330 nm, more preferably 240 to 290 nm, from the viewpoints of repairability, concealability, weather resistance, and the like of the resulting coating film. It is preferable that

  In this specification, the average primary particle diameter of the pigment is an average value of the particle diameters of the individual independent pigment particles. In general, pigment particles are present in an aggregated state, so it is difficult to distinguish and measure individual and independent particles with an ordinary particle size distribution measuring device. It is possible to measure the average primary particle diameter of the independent pigment particles themselves. In this specification, the average primary particle diameter of the pigment is a value obtained by observing the formed coating film with an electron microscope and averaging the maximum diameter of 20 pigment particles on a straight line drawn randomly on an electron micrograph. is there.

  The crystal form of the titanium dioxide pigment (C) may be either a rutile type or an anatase type, but the rutile type is preferred from the viewpoint of excellent concealability and weather resistance of the formed coating film.

  The titanium dioxide pigment (C) may be obtained by coating the surface of titanium dioxide with an inorganic oxide such as aluminum oxide, zirconium oxide or silicon dioxide; an organic compound such as amine or alcohol.

Black pigment (D)
Examples of the black pigment (D) include carbon black, iron black (black iron oxide), aniline black, and the like, and these can be used alone or in combination of two or more.

  In the present invention, the black pigment (D) is a black pigment having an average primary particle diameter of 30 to 500 nm, preferably 45 to 400 nm, more preferably 150 to 300 nm, from the viewpoint of the repairability of the resulting coating film. (D1) is contained in an amount of 40% by mass or more based on the total amount of the black pigment (D). Among them, the black pigment (D) is 55 to 100 mass%, preferably 70 to 100 mass%, more preferably 80 to 100 mass% based on the total amount of the black pigment (D1). %, More particularly preferably 90 to 100% by mass.

  In the present invention, by using a colored coating composition containing 40% by mass or more of the black pigment (D1) having an average primary particle diameter in the range of 30 to 500 nm based on the total amount of the black pigment (D). The reason why the color difference between the repaired part and the non-repaired part is not clear is not clear, but by using a black pigment having a relatively large particle size as a black pigment, the paint is applied to the object to be coated. It is inferred that the black pigment does not easily move until the coating is cured, and as a result, the black pigment is relatively uniformly present in the white base coat coating.

  Examples of the black pigment (D1) having an average primary particle size in the range of 30 to 500 nm include metal oxide pigments such as black iron oxide and titanium black pigment; carbon black and the like. Or it can be used in combination of two or more. Of these, black iron oxide and carbon black are preferred, and black iron oxide is more preferred from the viewpoint of excellent repairability of the resulting coating film.

  Examples of commercially available products of the black pigment (D1) include “Toda Color KN320” (manufactured by Toda Kogyo Co., Ltd.), “Special Black 100” (manufactured by EVONIK INDUSTRIES Co., Ltd.), and “Mitsubishi Carbon Black MA-220” (Mitsubishi Chemical Corporation). Company-made).

Colored paint composition The colored paint composition of the present invention contains the film-forming resin (A), the curing agent (B), the titanium dioxide pigment (C) and the black pigment (D), and the black pigment (D). However, this is a colored coating composition containing 40% by mass or more of the black pigment (D1) having an average primary particle diameter in the range of 30 to 500 nm based on the total amount of the black pigment (D).

In the colored coating composition of the present invention, the blending ratio of the film-forming resin (A), the curing agent (B), the titanium dioxide pigment (C) and the black pigment (D) is the same as that of the film-forming resin (A) and the curing agent. The total amount of (B) is preferably within the following range based on 100 parts by mass.
Film-forming resin (A): 30 to 95 parts by mass, preferably 50 to 90 parts by mass, more preferably 60 to 80 parts by mass,
Curing agent (B): 5-70 parts by mass, preferably 10-50 parts by mass, more preferably 20-40 parts by mass,
Titanium dioxide pigment (C): 5-160 parts by mass, preferably 10-140 parts by mass, more preferably 15-120 parts by mass,
Black pigment (D): 0.001 to 20 parts by mass, preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass.

  If necessary, the colored coating composition of the present invention is a colored pigment other than the titanium dioxide pigment (C) and the black pigment (D), an extender pigment, a bright pigment, a rust preventive pigment, a curing catalyst, a thickener, Additives for paints such as ultraviolet absorbers, light stabilizers, antifoaming agents, rust preventives, surface conditioners, antisettling agents, dispersants, surfactants and film-forming aids can be contained.

  Examples of coloring pigments other than the titanium dioxide pigment (C) and the black pigment (D) include white pigments such as zinc oxide, zinc sulfide, and lithopone; yellow iron oxide, titanium yellow, monoazo yellow, condensed azo yellow, and azomethine yellow. , Bismuth vanadate, benzimidazolone, isoindolinone, isoindoline, quinophthalone, benzidine yellow, permanent yellow and other yellow pigments; permanent orange and other orange pigments; red iron oxide, naphthol AS azo red, ansanthrone, anthraquinonyl Red pigments such as red, perylene maroon, quinacridone red, diketopyrrolopyrrole red, and permanent red; purple pigments such as cobalt violet, quinacridone violet, and dioxazine violet; cobalt blue, phthalos Ninburu, blue pigments such as vat blue; green pigments and the like, such as phthalocyanine green, which can be used singly or in combination of two or more.

  Examples of the extender pigment include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, and alumina white. Among them, barium sulfate and / or talc are preferably used.

  When the colored coating composition of the present invention contains the above extender, the amount of the extender is 1 to 4 parts by mass based on the total amount of the film-forming resin (A) and the curing agent (B) of 100 parts by mass. It is suitable to be in the range of 120 parts by weight, preferably 5 to 100 parts by weight, more preferably 10 to 80 parts by weight.

  Examples of the bright pigment include aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, aluminum oxide, mica, aluminum oxide coated with titanium oxide and iron oxide, titanium oxide and iron oxide. Mention may be made of coated mica, glass flakes, hologram pigments and the like. These glitter pigments can be used alone or in combination of two or more. The aluminum pigment includes non-leafing aluminum and leafing aluminum, and any of them can be used.

  The glitter pigment is preferably flake shaped. Specifically, as the bright pigment, flakes having a longitudinal dimension of about 1 to 100 μm, preferably about 5 to 40 μm, and a thickness of about 0.001 to 5 μm, preferably about 0.01 to 2 μm. A pigment can be preferably used.

  When the colored coating composition of the present invention contains the above-mentioned glittering pigment, the blending amount of the glittering pigment is that of the film-forming resin (A) and the curing agent (B) in the colored coating composition of the present invention. Based on the total amount of 100 parts by mass, it is usually in the range of 1-50 parts by mass, preferably 2-30 parts by mass, more preferably 3-20 parts by mass.

  The colored coating composition of the present invention can be prepared by mixing the components described above according to a known method. When the resin component is in the form of an organic solvent solution, an emulsion, or the like, it can be mixed as it is. The pigment component may be mixed with the dispersing resin to form a paste and then mixed. Moreover, when mixing each component, you may add an organic solvent, water, or these mixtures as needed.

  The colored coating composition of the present invention is preferably a liquid coating composition having a solid content of about 30 to 80% by mass, preferably about 40 to 70% by mass. The colored coating composition may be either an aqueous type or an organic solvent type. In this specification, the water-based paint is a paint whose main component is water, and the organic solvent-type paint is a paint that does not substantially contain water as a solvent.

  In addition, the black-and-white concealment film thickness of the colored coating composition of the present invention is about 10 to 50 μm, preferably about 15 to 40 μm, and more preferably about 20 to 30 μm. In the present invention, the black-and-white concealment film thickness refers to the concealment when the paint is applied on the concealment rate test paper defined in JIS K5600-4-1 (1999) while changing the film thickness and drying and curing. This means the minimum cured film thickness at which the white and black portions printed on the rate test paper cannot be visually discerned.

  The colored paint composition of the present invention described above is used as a white base coat paint (X) on the article to be coated by a method known per se, for example, air spray, airless spray, rotary atomizer, etc. Can be painted. When painting, electrostatic application may be performed. The coating film thickness is a cured film thickness and can be generally in the range of 10 to 60 μm, preferably 21 to 40 μm, and more preferably 25 to 35 μm. The colored coating composition of the present invention is usually applied so that the cured film thickness is 2 to 10 μm, preferably about 3 to 8 μm, thicker than the black and white masking film thickness.

  The colored coating composition of the present invention is a coated object in which a metal member formed with an undercoat film and / or an intermediate coat film of various electrodeposition paints and a plastic member such as a bumper are integrated as necessary. It is also possible to paint on top, which provides the advantage of matching the paint colors of the metal and plastic members.

  The white base coat film obtained by applying the colored paint composition of the present invention as the white base coat paint (X) is then cured by a known curing means. Examples of the curing means for the coating film include heat curing, ultraviolet curing, and electron beam curing. Of these, heat curing is preferable.

  The heat curing can be performed by a known heating means such as hot air heating, infrared heating, high frequency heating or the like. The heating temperature is preferably about 80 to 180 ° C, more preferably about 100 to 170 ° C, and still more preferably about 120 to 160 ° C. The heating time is not particularly limited, but is usually preferably about 10 to 60 minutes, more preferably about 20 to 40 minutes.

  In addition, when the colored coating composition of the present invention is an aqueous coating, after the colored coating composition of the present invention is applied, it is applied from the viewpoint of preventing the occurrence of coating film defects such as armpits before performing the heat curing. It is preferable to perform preheating, air blowing, or the like under heating conditions in which the film is not substantially cured. The preheating temperature is preferably about 40 to 100 ° C, more preferably about 50 to 90 ° C, and still more preferably about 60 to 80 ° C. The preheating time is preferably about 30 seconds to 15 minutes, more preferably about 1 to 10 minutes, and further preferably about 2 to 5 minutes. Moreover, the said air blow can be normally performed by spraying the air heated to the normal temperature or the temperature of about 25 to 80 degreeC on the coating surface of the to-be-coated article for about 30 seconds to 15 minutes.

Process (2)
According to the present invention, the glittering base coat paint (Y) is applied on the white base coat cured coating film formed in the step (1).
Bright base coat paint (Y)
The glitter base coat paint (Y) is a paint composition containing a glitter pigment, and is generally intended to give an excellent appearance to an object to be coated.

  The method for forming a multilayer coating film according to the present invention is such that the color tone of the white base coat film formed by the colored coating composition of the present invention and the color tone of the glitter base coat film formed by the glitter base coat paint (Y) are as follows. This is a coating method capable of obtaining a combined pearly white multi-layer coating film, and the glittering base coat film is coated in a state where the underlying white base coat film is not concealed.

  As the glittering base coat paint (Y), for example, those known per se that are usually used in the painting of automobile bodies can be used.

  Specifically, for example, a base resin such as an acrylic resin, a polyester resin, an alkyd resin, a urethane resin, and an epoxy resin having a crosslinkable functional group such as a carboxyl group and a hydroxyl group, and a polyisocyanate compound that may be blocked, A resin component composed of a curing agent such as a melamine resin or a urea resin can be prepared by mixing according to a known method together with a bright pigment, a pigment other than the bright pigment, other additives, and the like.

  When the resin component is in the form of an organic solvent solution, an emulsion, or the like, it can be mixed as it is. The pigment component may be mixed with the dispersing resin to form a paste and then mixed. Moreover, when mixing each component, you may add an organic solvent, water, or these mixtures as needed.

  The glittering base coat paint (Y) is preferably a liquid paint composition having a solid content of about 5 to 50% by mass, preferably about 10 to 45% by mass. Further, the glittering base coat paint (Y) may be either an aqueous type or an organic solvent type.

  As the glitter base coat paint (Y), the hydroxyl group-containing polyester resin (A1) and / or the hydroxyl group-containing acrylic resin (A2) exemplified in the description of the colored paint composition of the present invention is used as the base resin, and the curing agent is used. A thermosetting water-based paint using a melamine resin can be suitably used.

  As the glitter pigment contained in the glitter base coat paint (Y), for example, aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, aluminum oxide, exemplified in the description of the colored paint composition of the present invention, Examples thereof include mica, aluminum oxide coated with titanium oxide or iron oxide, mica coated with titanium oxide or iron oxide, glass flakes, and hologram pigments. Of these, it is preferable to use aluminum, aluminum oxide, mica, aluminum oxide coated with titanium oxide or iron oxide, mica coated with titanium oxide or iron oxide, and oxidation coated with mica, titanium oxide or iron oxide. It is particularly preferable to use mica coated with aluminum, titanium oxide or iron oxide. The above luster pigments can be used alone or in combination of two or more.

  The glitter pigment is preferably flake shaped. Specifically, as the bright pigment, flakes having a longitudinal dimension of about 1 to 100 μm, preferably about 5 to 40 μm, and a thickness of about 0.001 to 5 μm, preferably about 0.01 to 2 μm. A pigment can be preferably used.

  Further, the glittering base coat paint (Y) can contain a pigment other than the glittering pigment. Examples of pigments other than glitter pigments include color pigments and extender pigments, and these can be used alone or in combination of two or more.

  Examples of the colored pigment include titanium oxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment, selenium pigment, and perylene pigment.

  Examples of extender pigments include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, and alumina white. Among these, barium sulfate is preferably used.

  In addition, the glittering base coat paint (Y) further comprises a curing catalyst, a thickener, an ultraviolet absorber, a light stabilizer, an antifoaming agent, a plasticizer, an organic solvent, a surface conditioner, an anti-settling agent, etc. These usual paint additives can be contained alone or in combination of two or more.

  The black-and-white concealment film thickness of the glittering base coat paint (Y) is 50 μm or more, preferably 70 μm or more.

  The glittering base coat paint (Y) can be applied by a method known per se, for example, air spray, airless spray, rotary atomizer, etc., and electrostatic application may be performed. . The coating film thickness is usually 5 to 40 μm, preferably 8 to 30 μm, and more preferably 10 to 20 μm as a cured film thickness.

  Further, the glittering base coat paint (Y) obtains a synergistic effect with the lower white base coat film, so that the cured film thickness of the paint (Y) is thinner than the black-and-white concealment film thickness of the paint (Y). It is painted to become. Specifically, for example, the black-and-white concealment film thickness of the glittering base coat paint (Y) is 50 μm or more, and the paint film thickness of the paint (Y) is in the range of 5 to 40 μm in terms of the cured film thickness. Is preferred.

  In addition, when the glittering base coat paint (Y) is a water-based paint, after the glittering base coat paint (Y) is applied, the coating does not substantially cure from the viewpoint of preventing the occurrence of coating film defects such as armpits. It is preferable to perform preheating, air blowing, etc. under the conditions. The preheating temperature is preferably about 40 to 100 ° C, more preferably about 50 to 90 ° C, and still more preferably about 60 to 80 ° C. The preheating time is preferably about 30 seconds to 15 minutes, more preferably about 1 to 10 minutes, and further preferably about 2 to 5 minutes. Moreover, the said air blow can be normally performed by spraying the air heated to the normal temperature or the temperature of about 25 to 80 degreeC on the coating surface of the to-be-coated article for about 30 seconds to 15 minutes.

Step (3)
On the uncured coating film of the glittering base coat paint (Y) formed as described above, a clear coat paint (Z) is further applied.

  As the clear coat paint (Z), for example, a paint known per se that is usually used in the painting of automobile bodies can be used. Specifically, for example, a base resin such as an acrylic resin, a polyester resin, an alkyd resin, a urethane resin, an epoxy resin, or a fluororesin having a crosslinkable functional group such as a hydroxyl group, a carboxyl group, an epoxy group, or a silanol group, and melamine Resin, urea resin, polyisocyanate compound which may be blocked, carboxyl group-containing compound or resin, epoxy group-containing compound or resin-containing cross-linking agent as an organic solvent-based thermosetting paint, aqueous thermosetting paint Further, a thermosetting powder coating can be used. Among these, a thermosetting paint comprising a hydroxyl group-containing acrylic resin and a melamine resin, a thermosetting paint comprising a hydroxyl group-containing acrylic resin and an optionally blocked polyisocyanate compound, or a carboxyl group-containing resin and an epoxy group A thermosetting paint comprising a resin is particularly preferred.

  Further, as the clear coat paint (Z), a one-component paint or a multi-component paint such as a two-component urethane resin paint may be used.

  In addition, the clear coat paint (Z) can contain a color pigment, a bright pigment, a dye, etc. as long as it does not impair the transparency, if necessary, and an extender pigment, a curing catalyst, a thickener, An ultraviolet absorber, a light stabilizer, an antifoaming agent, a plasticizer, an organic solvent, a surface conditioner, an anti-settling agent and the like can be appropriately contained.

  The clear coat paint (Z) can be applied onto the paint film of the glittering base coat paint (Y) by a method known per se, for example, airless spray, air spray, rotary atomizing coater, etc. At this time, electrostatic application may be performed. The clear coat paint (Z) can be applied usually in a range of 10 to 60 μm, preferably 25 to 50 μm in cured film thickness.

  After the clear coat paint (Z) is applied, it may be preliminarily heated at room temperature for 1 to 60 minutes, preferably 3 to 20 minutes, or preheated at about 40 to 80 ° C. for 1 to 60 minutes. it can.

Step (4)
The multilayer coating film comprising the uncured base coat and the uncured clear coat formed as described above is cured simultaneously by a normal coating film heating means, for example, hot air heating, infrared heating, high-frequency heating, etc. Can be made. The heating temperature is preferably about 80 to 180 ° C, more preferably about 100 to 170 ° C, and still more preferably about 120 to 160 ° C. The heating time is not particularly limited, but is usually preferably about 10 to 60 minutes, more preferably about 20 to 40 minutes.

Repair coating method In the multilayer coating film forming method using the colored coating composition of the present invention, when a defective portion is found in the white base coat cured coating film formed in the step (1), the defective portion is removed. The defective portion can be repaired by grinding and removing to such an extent that the appearance of the coating film does not deteriorate due to the color difference from the ground portion, and subsequently applying a glittering base coat paint and a clear coat paint.

That is, in the multilayer coating film forming method using the colored coating composition of the present invention, the coating film can be repaired by a repairing method in which the following steps (I) to (V) are sequentially performed.
Step (I): A step of applying a white base coat paint (X) on an object to be coated and curing to form a white base coat cured coating film having L ^* of 70 or more,
Process (II): Grinding and removing the defective part generated in the white base coat cured coating film formed in process (I) within a range where the brightness difference ΔL ^* between the ground part and the non-ground part is 0.5 or less. The process of
Step (III): a step of coating the white base coat film formed in steps (I) and (II) with a glitter base coat paint (Y) to form a glitter base coat film,
Step (IV): a step of applying a clear coat paint (Z) on the uncured glitter base coat film formed in step (III) to form a clear coat film, and step (V): step A repair method for a white multi-layer coating film in which the uncured base coat film formed in (III) and the uncured clear coat film formed in step (IV) are heated and cured simultaneously.

Step (I)
In this step, a white base coat cured coating film having an L ^* of 70 or more is formed by applying and curing the colored coating composition of the present invention as a white base coat paint (X) on the object to be coated. Is done. Especially, it is suitable that L ^* is in the range of 75 to 95, preferably 80 to 90, from the viewpoint of excellent design properties of the resulting white multi-layer coating film.

  The white base coat cured coating film can be formed in the same manner as described in the step (1). Specifically, for example, the colored coating composition of the present invention is applied onto the article to be coated by a method known per se, for example, air spray, airless spray, rotary atomizing coating machine or the like. Can do. The coating film thickness is a cured film thickness and can be generally in the range of 10 to 60 μm, preferably 21 to 40 μm, and more preferably 25 to 35 μm.

  The white base coat film can be cured in the same manner as described in the step (1). Specifically, for example, it can be cured by heat curing, ultraviolet curing, electron beam curing or the like, and among them, it is preferable to cure by heat curing.

  The heat curing can be performed by a known heating means such as hot air heating, infrared heating, high frequency heating or the like. The heating temperature is preferably about 80 to 180 ° C, more preferably about 100 to 170 ° C, and still more preferably about 120 to 160 ° C. The heating time is not particularly limited, but is usually preferably about 10 to 60 minutes, more preferably about 20 to 40 minutes.

Step (II)
In the step (I), when the coating composition of the present invention is applied, or when the coating film is cured, dust or the like adheres to the uncured coating film. In the case where a defective portion is generated, the defective portion is ground and removed within a range where the brightness difference ΔL ^* between the ground portion and the non-ground portion is 0.5 or less. When the lightness difference ΔL ^* between the ground part and the non-ground part exceeds 0.5, the color difference between the ground part and the non-ground part is visually recognized, so that the appearance of the obtained white multi-layer coating film is deteriorated. .

The removal of the defective portion is usually performed by grinding the coating film using, for example, abrasive paper, a polishing cloth, or a device in which these are attached to a tool (sander). For example, first, the defective portion is ground and removed by using abrasive paper and / or a polishing cloth containing a relatively coarse abrasive of # 400 to 600, and then an abrasive having a fine particle size of # 1000 to 1500 In order to improve the finish, it is preferable to smooth the ground surface using a polishing paper and / or a polishing cloth containing. And in order to remove the powder of the coating film etc. which arose by grinding, it is preferable to wipe the coating surface with organic solvents, such as gasoline, and to degrease the coating surface simultaneously by it.
In this step, it is desirable to grind and remove the minimum required area of the coating surface of only the defective part and the peripheral part of the white base coat film. Further, the depth to be removed by grinding can be arbitrarily adjusted within a range in which the brightness difference ΔL ^* between the ground portion and the non-ground portion is 0.5 or less. Specifically, for example, when removing defective parts such as attached dust, the white base coat cured coating film is usually ground and removed in the depth direction by about 1 to 8 μm, preferably about 2 to 5 μm. Moreover, it is suitable that the white base coat cured coating film of the ground portion remains at 20 μm or more, preferably about 23 to 33 μm, more preferably about 25 to 28 μm. Further, it is preferable that the grinding removal be performed in a circular shape having a radius of about 2 cm with the defect portion as the center, while being inclined toward the center.

When a conventional paint is used as the white base coat paint, a color difference is likely to occur between the ground part and the non-ground part on the white base coat film, and the lightness difference ΔL ^* between the ground part and the non-ground part is 0. Within the range of 5 or less, the white base coat film could not be sufficiently ground, and there was a case where dust or the like at the defective part could not be completely removed. On the other hand, when the colored paint composition of the present invention is used as the white base coat paint, the difference in color between the ground part and the non-ground part hardly occurs, and the lightness difference ΔL ^* between the ground part and the non-ground part is 0. Even within the range of 5 or less, the white base coat film can be ground relatively deeply, and it is possible to completely remove dust and the like at defective portions.

  The reason why there is no difference in color between the ground part and the non-ground part when the colored paint composition of the present invention is used as a white base coat paint is not clear, but a black pigment having a relatively large particle size as a black pigment By using this, it is difficult for the black pigment to move between the time the paint is applied to the object and the coating is cured, and as a result, the black pigment is relatively contained in the white base coat film. It is inferred that it exists uniformly.

  As a method for causing the black pigment to uniformly exist in the white base coat film, a method using a color separation inhibitor is known. However, since the color separation inhibitor generally contains a surface conditioner, the surface conditioner is scattered on the white base coat film, and the glittering base coat paint (Y) is applied on the paint film. In some cases, repelling occurred. On the other hand, the present invention has the advantage that repelling is unlikely to occur because the black pigment can be uniformly present in the white base coat film without relying on the color separation inhibitor.

Step (III)
In this step, the glittering base coat paint (Y) is applied to the unrepaired portion of the white base coat film formed in the step (I) and the repair portion of the white base coat film formed in the step (II). By coating, a glittering base coat film is formed. Formation of the glittering base coat film can be carried out in the same manner as described in the step (2). Specifically, for example, a glittering base coat paint (Y) is applied to the unrepaired and repaired parts of the white base coat film by a method known per se, for example, air spray, airless spray, rotary atomizing coating machine, etc. This can be done by painting. The coating film thickness is a cured film thickness, and is usually 5 to 40 μm, preferably 8 to 30 μm, and more preferably 10 to 20 μm.

Step (IV)
In this step, the clear coat coating film (Z) is applied on the uncured glittering base coat coating film formed in the above step (III) to form a clear coat coating film. The formation of the clear coat film can be carried out in the same manner as described in the step (3). Specifically, for example, the clear coat paint (Z) is applied on the glittering base coat film by a method known per se, for example, air spray, airless spray, rotary atomizing coating machine, etc. Can do. The coating film thickness is a cured film thickness and can be generally in the range of 10 to 60 μm, preferably 25 to 50 μm.

Process (V)
In this step, the uncured base coat film formed in the step (III) and the uncured clear coat film formed in the step (IV) are simultaneously heat-cured. Heat curing of the uncured base coat film and clear coat film can be performed in the same manner as described in the step (4). Specifically, for example, the uncured base coat film and clear coat film can be cured by heating with a known heating means such as hot air heating, infrared heating, and high frequency heating. The heating temperature is preferably about 80 to 180 ° C, more preferably about 100 to 170 ° C, and still more preferably about 120 to 160 ° C. The heating time is not particularly limited, but is usually preferably about 10 to 60 minutes, more preferably about 20 to 40 minutes.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited only to these Examples. “Parts” and “%” indicate “parts by mass” and “% by mass”.

Production Example 1 of White Base Coat Paint (X)
70 parts by mass of a hydroxyl group-containing acrylic resin (Note 1), 30 parts by mass of melamine resin (Note 2), 120 parts of “TITANIX JR-405” (trade name, manufactured by Teika, titanium dioxide pigment, average primary particle size: 210 nm) and 0.5 parts of “Todacolor KN320” (trade name, manufactured by Toda Kogyo Co., Ltd., black iron oxide coloring pigment, average primary particle size: 270 nm) is mixed and dispersed in an organic solvent (equal mass solvent of toluene and xylene) Ford Cup No. 20 at 20 ° C. The white base coat paint (X-1) was obtained by adjusting the viscosity according to 4 to 21 seconds. In addition, all the compounding quantity of each component shows solid content mass.
(Note 1) Hydroxyl group-containing acrylic resin: Hydroxyl group-containing acrylic resin having a hydroxyl value of 70 mgKOH / g, an acid value of 14 mgKOH / g, and a number average molecular weight of 30,000.
(Note 2) Melamine resin: methyl-butyl mixed etherified melamine resin, weight average molecular weight 1,800.

Examples 2-12, Comparative Examples 1-2
A Ford Cup No. 20 at 20 ° C. was prepared in the same manner as in Example 1 except that the pigment composition was as shown in Table 1 below. The white base coat paints (X-2) to (X-14) having a viscosity according to 4 of 21 seconds were obtained.

(Note 3) “TITANIX JR-605”: trade name, manufactured by Teika, titanium dioxide pigment, average primary particle size of 250 nm
(Note 4) “TITANIX JR-301”: trade name, manufactured by Teika, titanium dioxide pigment, average primary particle size of 300 nm
(Note 5) “Special Black 100”: trade name, manufactured by EVONIK INDUSTRIES, carbon black coloring pigment, average primary particle size: 50 nm
(Note 6) “Mitsubishi Carbon Black MA-220”: trade name, manufactured by Mitsubishi Chemical Corporation, carbon black coloring pigment, average primary particle size: 55 nm
(Note 7) “Mitsubishi Carbon Black MA-100”: trade name, manufactured by Mitsubishi Chemical Corporation, carbon black coloring pigment, average primary particle size: 20 nm.

Production of test plates Using the white base coat paints (X-1) to (X-14) obtained in Examples 1 to 12 and Comparative Examples 1 and 2, test plates were produced as follows. An evaluation test was conducted.

(Preparation of test article)
A thermosetting epoxy resin cationic electrodeposition coating composition (trade name “Electron GT-10”, manufactured by Kansai Paint Co., Ltd.) is applied to a zinc phosphate-treated cold rolled steel sheet having a width of 100 mm, a length of 300 mm, and a thickness of 0.8 mm. ) Was electrodeposited to a cured film thickness of 20 μm and cured by heating at 170 ° C. for 30 minutes. Next, an intermediate coating composition (trade name “TP-65-2 No. 8007”, manufactured by Kansai Paint Co., Ltd., polyester resin / amino resin organic solvent-based coating composition) is cured on this electrodeposition coating film. It was coated to 35 μm and cured by heating at 140 ° C. for 30 minutes. Thus, an object to be tested was prepared by forming an electrodeposition coating film and an intermediate coating film on the steel plate.

Example 13
The white base coat paint (X-1) obtained in Example 1 is electrostatically applied to the above test object so as to have a cured film thickness of 30 μm using a rotary atomizing electrostatic coater. The mixture was allowed to stand at room temperature for 7 minutes and then heated at 140 ° C. for 30 minutes to obtain a white base coat cured coating film. Next, L ^* of the obtained white base coat film was measured using a multi-angle spectrocolorimeter “CM-512m3” (manufactured by Konica Minolta Co., Ltd.) under measurement conditions with an illumination incident angle of 45 °. Next, the white base coat film surface is formed into a circle having a radius of about 2 cm, and until the cured film thickness of the white base coat film at the center of the circle becomes 25 μm, the # 600 water resistant abrasive paper and the # 1200 water resistant paper It was removed by polishing with abrasive paper. Next, a glittering base coat paint (trade name “Magicron TB-516 No. 070”, manufactured by Kansai Paint Co., Ltd., acrylic resin / amino resin-based organic solvent-type paint composition is applied to the entire test article including the polishing removal portion. ) Was electrostatically coated using a rotary atomizing type electrostatic coating machine so as to have a cured film thickness of 15 μm. After leaving at room temperature for 7 minutes, a clear coat paint (trade name “Magicron Kino-1210TW”, manufactured by Kansai Paint Co., Ltd., acrylic resin-based organic solvent paint composition) is rotated on the uncured glittering base coat film. Using an atomizing type electrostatic coating machine, coating was performed so that the cured film thickness was 40 μm. After leaving at room temperature for 7 minutes, it was heated at 140 ° C. for 30 minutes to simultaneously cure the glittering base coat film and the clear coat film to prepare a test plate.

Examples 14-24, Comparative Examples 3-4
A test plate was produced in the same manner as in Example 13 except that the paint shown in Table 2 was used as the white base coat paint.

Evaluation Test Each test plate obtained in Examples 13 to 24 and Comparative Examples 3 to 4 was evaluated by the following test method. The evaluation results are shown in Table 2.

(Test method)
Repairability: Using a multi-angle spectrocolorimeter “CM-512m3” (manufactured by Konica Minolta Co., Ltd.), with and without the portion where the white base coat film was polished and removed under the measurement conditions with an illumination incident angle of 45 ° The brightness difference ΔL ^* (JIS K 5600-4-6 (1999)) was measured. The smaller the ΔL ^* , the smaller the color difference between the repaired part and the non-repaired part, and the better the repairability of the coating film.

Claims (5)

The following steps (1) to (4),
Step (1): A step of applying a white base coat paint (X) on an object to be coated and curing to form a white base coat cured coating film having L * of 70 or more,
Step (2): a step of coating the white basecoat cured coating film formed in Step (1) with a glittering basecoat coating (Y) to form a glittering basecoat coating film,
Step (3): a step of applying a clear coat paint (Z) on the uncured glitter base coat film formed in step (2) to form a clear coat film, and step (4): step In the white multi-layer coating film forming method in which the uncured base coat film formed in (2) and the uncured clear coat film formed in step (3) are simultaneously heated and cured, A colored coating composition for use as a base coat coating (X), which is a film-forming resin (A), a curing agent (B), and a titanium dioxide pigment (C) having an average primary particle size in the range of 200 to 350 nm. ) And a black pigment (D), and the blending ratio of the film-forming resin (A), the curing agent (B), the titanium dioxide pigment (C), and the black pigment (D) is the film-forming resin (A) and 100 parts by mass of the total amount of the curing agent (B) As a reference, the film-forming resin (A) is 30 to 95 parts by mass, the curing agent (B) is 5 to 70 parts by mass, the titanium dioxide pigment (C) is 15 to 160 parts by mass, and the black pigment (D) is 0.00. The black pigment (D1) in the range of 01 to 5 parts by mass and the black pigment (D) having an average primary particle diameter in the range of 30 to 300 nm is based on the total amount of the black pigment (D). 40% by mass or more of a colored coating composition, The following steps (1) to (4),
Step (1): A step of applying a white base coat paint (X) on an object to be coated and curing to form a white base coat cured coating film having L ^* of 70 or more,
Step (2): a step of coating the white basecoat cured coating film formed in Step (1) with a glittering basecoat coating (Y) to form a glittering basecoat coating film,
Step (3): a step of applying a clear coat paint (Z) on the uncured glitter base coat film formed in step (2) to form a clear coat film, and step (4): step In the white multi-layer coating film forming method in which the uncured base coat film formed in (2) and the uncured clear coat film formed in step (3) are simultaneously heated and cured, The base coat paint (X) contains a film-forming resin (A), a curing agent (B), a titanium dioxide pigment (C) and a black pigment (D) whose average primary particle diameter is in the range of 200 to 350 nm , The blending ratio of the film-forming resin (A), the curing agent (B), the titanium dioxide pigment (C) and the black pigment (D) is 100 parts by mass of the total amount of the film-forming resin (A) and the curing agent (B). As a standard, the film-forming resin (A) is 30 95 parts by weight, 5 to 70 parts by weight curing agent (B), is in the range from 15 to 160 parts by weight of titanium dioxide pigment (C) is a black pigment (D) is 0.01 to 5 parts by weight, and black The pigment (D) is a colored coating composition containing 40% by mass or more of a black pigment (D1) having an average primary particle diameter in the range of 30 to 300 nm, based on the total amount of the black pigment (D). A method for forming a white multi-layer coating film, comprising: The white multilayer coating film forming method according to claim 2 , wherein the article to be coated is a vehicle body on which an undercoat film and / or an intermediate coat film is formed. Articles coated with white multilayer coating film forming method according to claim 2 or 3. The following steps (I) to (V),
Step (I): A step of applying a white base coat paint (X) on an object to be coated and curing to form a white base coat cured coating film having L ^* of 70 or more,
Process (II): Grinding and removing the defective part generated in the white base coat cured coating film formed in process (I) within a range where the brightness difference ΔL ^* between the ground part and the non-ground part is 0.5 or less. The process of
Step (III): a step of coating the white basecoat cured coating film formed in steps (I) and (II) with a glittering basecoat coating (Y) to form a glittering basecoat coating film,
Step (IV): a step of applying a clear coat paint (Z) on the uncured glitter base coat film formed in step (III) to form a clear coat film, and step (V): step In the repair method of the white multi-layer coating film in which the uncured base coat film formed in (III) and the uncured clear coat film formed in step (IV) are heated and cured simultaneously, The base coat paint (X) contains a film-forming resin (A), a curing agent (B), a titanium dioxide pigment (C) and a black pigment (D) whose average primary particle diameter is in the range of 200 to 350 nm. The blending ratio of the film-forming resin (A), the curing agent (B), the titanium dioxide pigment (C), and the black pigment (D) is 100 mass of the total amount of the film-forming resin (A) and the curing agent (B). Film-forming tree 30-95 parts by mass of (A), 5-70 parts by mass of curing agent (B), 15-160 parts by mass of titanium dioxide pigment (C), and 0.01-5 parts by mass of black pigment (D). And the black pigment (D) contains 40% by mass or more of the black pigment (D1) having an average primary particle diameter in the range of 30 to 300 nm based on the total amount of the black pigment (D). A method for repairing a white multilayer coating film, which is a colored coating composition.