JP6762752B2 - Selection method of base forming paint and repair painting method - Google Patents

Description

The present invention relates to a method for selecting a base forming paint, which is useful for repair painting of a vehicle such as an automobile, and a repair painting method using the base forming paint selected by the selection method.

Generally, in the painting of automobile outer panels, etc., the undercoat paint is applied on the base material surface, the intermediate coat paint is applied, the colored topcoat paint is applied on the coating film by the intermediate coating paint, and the colored topcoat coating is applied on the colored topcoat paint. Top clear paint is applied to.

In general, a gray color is generally used for the intermediate coating paint provided under the colored topcoat coating, and in the coating process of the colored topcoat coating, the coating is performed until the gray color of the intermediate coating is completely hidden. However, if the color hiding property of the colored topcoat paint is poor, it becomes necessary to increase the film thickness, which is inefficient in terms of the amount of paint used and the labor required for painting.

Therefore, even if the colored topcoat coating film does not reach the concealing film thickness, the gray color of the intermediate coating film, which is the base, is adjusted to a brightness suitable for the colored topcoat coating film, thereby finally obtaining a multi-layer coating. Attempts have been made to achieve the desired color for the appearance of the film.

For example, in Patent Document 1, the sum of the absolute values of the spectral reflectance differences in a specific wavelength region between the topcoat coating film and the intermediate coating film is set to be small so that the topcoat coating film has a low concealment coating color. It is described that even if there is, a multi-layer coating film having an excellent appearance can be obtained with a normal coating amount.

In Patent Document 2, when the reflectance of the topcoat coating film measured at the wavelength of the minimum absorption of the topcoat coating film and the reflectance of the primer (intermediate coating) are the same, the multi-layer coating film having the desired appearance is obtained. It is stated that it can be obtained efficiently.

Further, an attempt has been made to use a color primer, which is a mixture of a gray primer and a color topcoat, as a base-forming paint for the colored topcoat (Patent Document 3).

However, although the techniques described in Patent Documents 1 to 3 are effective especially in paint colors such as red and yellow, there are cases where the effect is insufficient in metallic paint colors having a glittering feeling.

By the way, in the repair coating of the damaged part generated on the coated surface of the outer panel of the automobile, usually, the damaged part is sanded to the periphery thereof, putty is applied, and then the primer surfacer coating is applied, and further, the color of the automobile body is covered. The topcoat is applied with a colored base topcoat for repair so that the appearance does not look strange.

The above repair coloring base topcoat paint is applied in stages until the underlying color cannot be seen through while comparing with the surrounding color, and if the repair coloring base topcoat paint is water-based, Since setting and preheating were required for each painting at each stage, it took a lot of labor and time to perform this process. Therefore, it is important to select the coating color of the primer surfacer layer so that the coloring base topcoat coating film reaches the target color even if the number of times the coloring base topcoat coating is applied is small.

However, when a water-based metallic base is used as the repair topcoat, a phenomenon occurs in which the glittering feeling differs depending on the viewing angle of the formed metallic base coating film, so it is particularly important to select a primer surfacer coating film that is suitable for the repair metallic base coating film. It was difficult.

Regarding such a problem, in Patent Document 4, the flip-flop property is improved by selecting a primer surfacer having a maximum reflectance at a specific magnification with respect to a 105-degree maximum reflectance at a specific wavelength of the colored coating film to be repaired. It is described that the target coating film appearance can be suitably obtained even if the metallic coating film has, without thickly coating the repair base paint.

However, Patent Document 4 has a problem that a worker must prepare a target primer surfacer paint by mixing appropriate amounts of white paint and black paint at a repair painting site.

It is generally said that there are more than thousands of paint colors for automobile outer panels. Especially in recent years, the paint color of new cars has become brighter and the feeling of brilliance has increased, so the difficulty of repair painting has become higher. There is. Therefore, it is necessary to develop a method for more easily obtaining an optimum base-forming paint suitable for the repair coloring base topcoat paint.

Japanese Unexamined Patent Publication No. 58-16696 International Publication 1997/043052 JP-A-2002-020894 Japanese Unexamined Patent Publication No. 2008-307476

An object of the present invention is to select an optimum base forming paint to be provided under a colored base coating film for repair in order to obtain a multi-layer repair coating film that can obtain the desired coating film appearance even with a small number of coatings. The present invention is to provide a repair coating method using a base forming paint selected by the method.

As a result of diligent studies on the above-mentioned problems, the present inventors have made a coating having a specific relationship with the spectral reflectance curve of the coloring base coating material from among a plurality of different types of base forming coating materials having a specific pigment composition. By selecting the above, it has been found that a coating material for forming a base suitable for a colored base coating film can be obtained without requiring a great deal of labor, and the present invention has been reached.

That is, the present invention includes the following inventions.

Item 1. A paint for forming a base layer provided under the colored base coating film by the colored base paint for repair for repairing a damaged part of the coated body provided with the colored base cured coating film.
For 100 parts by mass of resin component
45 to 110 parts by mass of white pigment and 20 to 300 parts by mass of extender pigment,
Base forming paint (A1), including
For 100 parts by mass of resin component
White pigment 10 parts by mass or more and less than 45 parts by mass,
Substrate forming paint (A2) containing 20 to 300 parts by mass of extender pigment and 0.1 to 5.0 parts by mass of black pigment,
1 part by mass or more of white pigment and less than 10 parts by mass with respect to 100 parts by mass of the resin component.
A coloring base in the repair target from among a plurality of different types of base-forming paint groups including a base-forming paint (A3) containing 20 to 300 parts by mass of an extender pigment and 0.1 to 5.0 parts by mass of a black pigment. A method for selecting a base-forming paint, which comprises selecting a paint for forming a base layer having a spectral reflectance average value having the smallest absolute value of a difference from the average value of the spectral reflectance of a cured coating film.

Item 2. Item 2. The selection method according to Item 1, wherein the base forming paints (A1) to (A3) are two-component reaction-curable paints.

Item 3. A plurality of different types of base-forming paints can be obtained by mixing two or more of the base-forming paints (A1) to (A3) in addition to the base-forming paints (A1) to (A3). Item 3. The selection method according to Item 1 or 2, further comprising a base forming paint (An).

Item 4. The base-forming paint (An) is a mixture (A12) of the base-forming paint (A1) and the base-forming paint (A2), and a mixture (A23) of the base-forming paint (A2) and the base-forming paint (A3). Item 3. The selection method according to Item 3, wherein the base forming paint group is composed of five types of paint groups.

Item 5. The average value of the spectral reflectances of the colored base cured coating film and the underlying layer is the average value of the reflectances of 2.0% or more measured at every 10 nm in the wavelength range of 400 to 700 nm. The selection method described in any one of the items.

Item 6. Item 2. The selection method according to any one of Items 1 to 5, wherein the spectral reflectance of the colored base cured coating film and the underlying layer is determined by a method of irradiating light rays from multiple directions in a ring shape.

Item 7. Item 2. The selection method according to any one of Items 1 to 6, wherein the spectral reflectance of the colored base cured coating film and the underlying layer is determined by the incident angle of light rays in the range of 10 to 90 °.

Item 8. The damaged part of the coated body provided with the coloring base cured coating film is coated with the base forming paint selected by the selection method according to any one of Items 1 to 7, and repaired on the formed base layer. A repair painting method characterized by painting a colored base paint for use.

Item 9. Item 8. The repair coating method according to Item 8, wherein the colored base paint for repair is applied with a film thickness less than the concealing film thickness.

Although the base-forming paint used in the method of the present invention is composed of a small number of varieties, the target coating film appearance can be finally obtained in response to a huge variety of coloring base coating colors. It is possible to contribute to space saving in the above and to reduce the labor required for the base forming process.

Further, in the repair painting using the base forming paint, the coloring base paint can be applied in a small number of times, and the total time required for the repair painting process, the labor of the operator, and the amount of the coloring base paint used can be significantly reduced. Is something that can be done.

First, the base forming paint used in the method of the present invention will be described.

<Paint for base formation>
As the resin component contained in the base-forming paint in the present invention, those that can be usually used in the paint field can be used.

Specific examples of the resin contained in the resin component include acrylic resin, polyester resin, cellulose resin, polyurethane resin, silicone resin, epoxy resin, alkyd resin, and two or more of these modified resins, which are organic used in the coating field. Conventionally known resin of solvent type or water type can be used without limitation, and two or more of these can be used in combination.

It is desirable that the base forming paint is a two-component reaction-curable paint. This is because the two-component reaction-curable coating material provides a dense and excellent abrasive layer. A two-component reaction-curable paint is a component containing a resin component containing a reactive functional group-containing resin as a first component and a compound having two or more functional groups capable of reacting with the reactive functional group in one molecule. Is a paint containing the second component.

Examples of the resin component contained in the base material forming paint include a polyol compound and a polyisocyanate compound. When the resin component is composed of a combination of a base resin component and a curing agent component, such as a combination of a polyol compound and a polyisocyanate compound, the content of the resin component is the total content of the base resin component and the curing agent component. Is.

The polyol is not particularly limited, but an acrylic polyol is preferable.

The acrylic polyol can be a hydroxyl group-containing copolymer of a polymerizable unsaturated monomer containing at least one (meth) acryloyl group-containing monomer.

Examples of the (meth) acryloyl group-containing monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and tert-butyl (meth). Linear or branched alkyl (meth) acrylates such as acrylates, pentyl (meth) acrylates, hexyl (meth) acrylates, 2-ethylhexyl (meth) acrylates, lauryl (meth) acrylates, stearyl (meth) acrylates; cyclohexyl (meth). Alicyclic alkyl (meth) acrylates such as acrylates and isobornyl (meth) acrylates; aralkyl (meth) acrylates such as benzyl (meth) acrylates; 2-methoxyethyl (meth) acrylates, 2-ethoxyethyl (meth) acrylates and the like. Alkoxyalkyl (meth) acrylate; hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate, molecules. A hydroxyl group-containing (meth) acryloyl monomer such as a polyoxyethylene chain-containing (meth) acrylate having a hydroxyl group at the end; "Plaxel FA-1", "Plaxel FA-2", "Plaxel FA-2D", "Plaxel FA-3" , "Plaxel FA-4", "Plaxel FA-5", "Plaxel FM-1", "Plaxel FM-2", "Plaxel FM-2D", "Plaxel FM-3", "Plaxel FM-4" , "Plaxel FM-5" (both manufactured by Daicel Chemical Co., Ltd., trade name) and the like lactone-modified hydroxyalkyl (meth) acrylate; perfluoroalkyl (meth) acrylate; N, N-diethylaminoethyl (meth) acrylate. N, N-dialkylaminoalkyl (meth) acrylate; (meth) acrylamide; allyl (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1 , 3-butylene glycol di (meth) acrylate, trimethylpropantri (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (Meta) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol di (meth) acrylate, 1,1,1-trishydroxymethylethanedi (meth) acrylate, 1,1,1- A (meth) acryloyl monomer having at least two polymerizable unsaturated groups in one molecule such as trishydroxymethylethanetri (meth) acrylate and 1,1,1-trishydroxymethylpropantri (meth) acrylate; (meth). ) Acrylic acid; carbonyl group-containing (meth) acryloyl monomer such as acetoacetoxyethyl (meth) acrylate and diacetone (meth) acrylamide; glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexyl Epoxy group-containing (meth) acryloyl monomer such as methyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate; isocyanato such as isocyanatoethyl (meth) acrylate. Group-containing (meth) acryloyl monomer; alkoxysilyl group-containing (meth) acryloyl monomer such as γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltriethoxysilane; dicyclopentenyloxyethyl (meth) acrylate, dicyclopentenyl Examples thereof include oxidatively curable group-containing (meth) acryloyl monomers such as oxypropyl (meth) acrylate and dicyclopentenyl (meth) acrylate, and these can be used alone or in combination of two or more.

In addition, the acrylic polyol can also contain a polymerizable unsaturated monomer other than the (meth) acryloyl group-containing monomer as a copolymerization component. Examples of such polymerizable unsaturated monomers include (meth) acrylonitrile; vinyl ester compounds such as vinyl acetate and vinyl propionate; vinyl aromatic compounds such as styrene and α-methylstyrene; triallyl isocyanurate and diallyl terephthalate. , A polyvinyl compound having at least two polymerizable unsaturated groups in one molecule such as divinylbenzene; carboxyl group-containing polymerizable unsaturated monomers such as maleic acid, crotonic acid and β-carboxyethyl acrylate; allyl alcohol and the like. Hydroxyl group-containing polymerizable unsaturated monomer; carbonyl group such as (meth) achlorine, formylstyrene, vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone, etc.), acetoacetoxyallyl ester, etc. Containing polymerizable unsaturated monomer; Epoxy group-containing polymerizable unsaturated monomer such as allylglycidyl ether; Isocyanato group-containing polymerizable unsaturated monomer such as m-isopropenyl-α and α-dimethylbenzylisocyanate; Vinyltrimethoxysilane, vinyl An alkoxysilyl group-containing polymerizable unsaturated monomer such as triethoxysilane; an oxidatively curable group-containing unsaturated monomer such as an epoxy group-containing polymerizable unsaturated monomer or a reaction product of a hydroxyl group-containing polymerizable unsaturated monomer and an unsaturated fatty acid. Examples thereof include saturated monomers, which can be used alone or in combination of two or more.

The acrylic polyol has a weight average molecular weight in the range of 5,000 to 80,000, preferably 6,000 to 70,000, and a solid content hydroxyl value in the range of 200 mgKOH / g or less, preferably in the range of 30 to 150 mg / KOH. It is suitable that the solid content acid value is in the range of 1 to 30 mgKOH / g, preferably 3 to 15 mgKOH / g. This is because the adhesion of the base layer is improved.

In the present specification, the weight average molecular weight is a value obtained by converting the weight average molecular weight measured by a gel permeation chromatograph (manufactured by Toso Co., Ltd., “HLC8120GPC”) with reference to the weight average molecular weight of polystyrene. The columns are "TSKgel G-4000H x L", "TSKgel G-3000H x L", "TSKgel G-2500H x L", "TSKgel G-2000H x L" (all manufactured by Tosoh Corporation, trade name). ), Mobile phase; tetrahydrofuran, measurement temperature; 40 ° C., flow velocity; 1 ml / min, detector; RI conditions.

Further, as the acrylic polyol, a lactone-modified acrylic polyol is suitable from the viewpoint of adhesion of the underlying layer.

Examples of the polymerizable unsaturated monomer used for lactone-modifying the acrylic polyol include lactone-modified hydroxyalkyl (meth) acrylates as listed above, and the copolymerization ratio thereof is used in the production of the acrylic polyol. It is suitable that the content is in the range of 1 to 50% by mass, preferably 5 to 30% by mass based on the totally polymerizable unsaturated monomer to be obtained from the viewpoint of adhesion of the base layer to the topcoat coating film and polishability.

The polyisocyanate compound is a polyisocyanate compound having two or more isocyanate groups in one molecule, and specific examples thereof include hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated xyl. Polyisocyanate compounds such as range isocyanate, xylylene diisocyanate, meta-tetramethylxylylenesidiisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, lysine diisocyanate, or these polyisocyanates and polyhydric alcohols, low molecular weight Additives with polyester resin or water, cyclized polymers of each polyisocyanate as described above, isocyanate / biuret, etc. may be used, and these may be used alone or in combination of two or more. May be.

The base-forming paint may appropriately contain pigments other than the above, organic solvents, viscosity modifiers, curing catalysts, pigment dispersants, surface modifiers, resin particles and other paint additives.

Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, esters such as ethyl acetate and butyl acetate, toluene and xylene. Such as aromatic hydrocarbons, alcohols such as methanol, ethanol, propanol and butanol, tetrahydrofuran, dimethylformamide, petroleum hydrocarbons and the like can be mentioned.

The base-forming paint group in the present invention is characterized by containing three types of base-forming paints (A1) to (A3) having the following compositions having different pigment compositions. When the base forming paint group includes the following base forming paints (A1) to (A3), and according to the selection criteria described later, the repair coloring base paint is applied on the base layer to a thickness equal to or less than the concealing film thickness. This is because it is extremely easy to select a base-forming paint for obtaining the desired hue of the multi-layer repair coating film.

The base forming paint (A1) is prepared with respect to 100 parts by mass of the resin component.
45 to 110 parts by mass of white pigment, preferably 50 to 100 parts by mass, and 20 to 300 parts by mass of extender pigment, preferably 30 to 210 parts by mass.
It is included within the range of
Preferably, the black pigment is not contained or may be contained in an amount of 5.0 parts by mass or less (0 to 5.0 parts by weight).

The base forming paint (A1) is prepared with respect to 100 parts by mass of the resin component.
The white pigment may be contained in the range of 60 to 110 parts by mass, preferably 65 to 100 parts by mass, and the extender pigment 35 to 300 parts by mass, preferably 75 to 250 parts by mass.

The base forming paint (A2) is applied to 100 parts by mass of the resin component.
White pigment 10 parts by mass or more and less than 45 parts by mass, preferably 15 or more and less than 40 parts by mass,
The extender pigment is contained in the range of 20 to 300 parts by mass, preferably 70 to 250 parts by mass, and the black pigment in the range of 0.1 to 5.0 parts by mass, preferably 0.1 to 1.0 part by mass.

The base forming paint (A2) is applied to 100 parts by mass of the resin component.
White pigment 30 parts by mass or more and less than 60 parts by mass, preferably 35 or more and less than 65 parts by mass,
The extender pigment may be contained in the range of 35 to 300 parts by mass, preferably 75 to 270 parts by mass, and the black pigment in the range of 0.1 to 5.0 parts by mass, preferably 0.1 to 1.0 part by mass.

The base forming paint (A3) is used with respect to 100 parts by mass of the resin component.
White pigment 1 part by mass or more and less than 10 parts by mass, preferably 2 parts by mass or more and less than 7 parts by mass.
It is suitable to contain 20 to 300 parts by mass of the extender pigment, preferably 90 to 270 parts by mass, and 0.1 to 5.0 parts by mass of the black pigment, preferably more than 1.0 part by mass and 5 parts by mass or less. ing.

The base forming paint (A3) is used with respect to 100 parts by mass of the resin component.
White pigment 1 part by mass or more and less than 30 parts by mass, preferably 3 parts by mass or more and less than 35 parts by mass.
The extender pigment may be contained in an amount of 35 to 300 parts by mass, preferably 75 to 280 parts by mass, and 0.1 to 5.0 parts by mass of the black pigment, preferably more than 1.0 part by mass and 5 parts by mass or less. it can.

In the relationship between the base forming paints (A1), (A2) and (A3), the content of the black pigment is preferably (A1) at the lowest and (A3) at the highest.

Examples of the white pigment include titanium dioxide, white lead, aluminum oxide and the like, and these can be used alone or in combination of two or more.

Examples of the extender pigment include talc, zinc oxide, calcium carbonate, barium sulfate, barium carbonate, aluminum silicate, gypsum, clay, silica, white carbon, diatomaceous earth, magnesium carbonate, alumina white, gloss white, mica powder and the like. These can be used alone or in combination of two or more.

Examples of the black pigment include carbon black, acetylene black, lamp black, bone black, graphite, iron black, aniline black and the like, and these can be used alone or in combination of two or more.

The base forming paint group is obtained by mixing two or more of the base forming paints (A1) to (A3) in addition to the base forming paints (A1) to (A3). It may be a group further containing a paint (An). In a preferred embodiment of the present invention, the base-forming paint group including the base-forming paints (A1) to (A3) is a group consisting of three types of base-forming paints (A1) to (A3), or base-forming. Any of the group further containing the base forming paint (An) obtained by mixing two or more of the base forming paints (A1) to (A3) in addition to the three types of the base forming paints (A1) to (A3). Is it?

The base forming paint (An) may be previously manufactured by the paint manufacturer, or may be repair-painted using the base forming paints (A1) to (A3) provided by the paint manufacturer. It may be prepared at the repair painting site by a trader.

For example, the base-forming paint (An) is a mixture (A12) of the base-forming paint (A1) and the base-forming paint (A2), and a mixture of the base-forming paint (A2) and the base-forming paint (A3) (A3). A23), it is suitable that the base forming paint group consists of five types of paint groups.

In the present invention, the base-forming paint (A12) and the base-forming paint (A23) can be prepared by using the base-forming paints (A1) to (A3), so that even if the paint color to be repaired is wide, it is small. It is possible to easily select the optimum base forming paint for each type.

The mixing ratio of the base forming paint (A1) and the base forming paint (A2) in the base forming paint (A12) is not particularly limited. For example, the ratio of (A1): (A2) can be about 1:10 to 10: 1, preferably about 1: 5 to 5: 1, and more preferably about 1: 2 to 2: 1. Further, the mixing ratio of the base forming paint (A2) and the base forming paint (A3) in the base forming paint (A23) is not particularly limited. For example, the ratio of (A2): (A3) can be about 1:10 to 10: 1, preferably about 1: 5 to 5: 1, and more preferably about 1: 2 to 2: 1.

In particular, the base-forming paint (A12) is an equal amount mixture of the base-forming paint (A1) and the base-forming paint (A2), and the base-forming paint (A23) is the base-forming paint (A2) and the base-forming paint. An equal amount mixture of the paint (A3) is suitable because the paint preparation work becomes simpler.

<Calculation of the average spectral reflectance of the colored base cured coating film and the base layer>
In the method of the present invention, it is necessary to obtain the average value of the spectral reflectances of the colored base cured coating film to be repaired and each base layer formed from the base forming paint group.

In the present specification, as the average value of the spectral reflectance, for example, the average value of the reflectance having a measured value of 2.0% or more at every 10 nm in the wavelength range of 400 to 700 nm is calculated. it can. (That is, if the reflectance value is less than 2.0%, it is not included as the spectral reflectance average value data.)
The spectral reflectance can be obtained by measuring the reflectance with a colorimeter, and the measuring method is not particularly limited and may be a known method or a colorimeter. For example, a method of irradiating light rays from one direction or a light source. There are various methods such as irradiating light rays from multiple directions in an annular shape arranged at radial intervals, an annular light beam irradiation method in which the light source is arranged on the circumference, and a method of irradiating light rays from multiple directions with an integrating sphere. Can be mentioned. Examples of measuring devices capable of measuring reflectance by such a method include "CM512 series" such as "CM-512m" and "CM-512m3A" (trade name, manufactured by Konica Minolta), "MA-". "MA-68 series" (trade name, manufactured by X-Rite) such as "68II", "MA-94", "MA-96", "MA-98", "BYK-mac"
, "BYK-mac color", "BYK-mac Robotech", etc. "BYK series" (trade name, manufactured by BYK Gardner), "GCMS-4", "GCMS-3B", "GCMS-11", etc. "GCMS series" (manufactured by Murakami Color Technology Research Institute) and the like can be mentioned.

The spectral reflectances of the colored base cured coating film and the base layer can be approximated by the values measured from above the top clear coating film.

The angle of incidence of the light beam for measuring the spectral reflectance is, for example, in the range of 10 to 90 °, preferably 25 to 90 °, and more preferably 50 to 90 °. When the incident angle is within this range, even if the colored base coating film for repair is less than the concealing film thickness, it is used for forming a base layer that can be a multi-layer repair coating film having a desired hue appearance. It becomes possible to select the paint more accurately. In the embodiment of the present invention, the incident angle of the light beam for measuring the spectral reflectance is preferably fixed to a value in the above range.

In the present specification, the incident angle means the angle formed by the direction in which the light beam is incident and the normal line of the test plate at that point.

In the method of the present invention, the spectral reflectance average value of the colored base cured coating film may be measured and calculated at any time by measuring and calculating the spectral reflectance of the coating material to be repaired, for example, the spectral reflectance average of the coating color of the automobile outer panel. The value may be stored in a database in advance.

In a preferred embodiment of the present invention, the spectral reflectance of the base layer is such that the base layer formed by the base forming paint (A1) is the minimum and the base layer formed by the base forming paint (A3) is the maximum. When the base-forming paint (A12) and the base-forming paint (A23) are used, the value of the base layer formed by the base-forming paint (A12) is the value of the base layer formed by the base-forming paint (A1). The value between the base layer and the base layer formed by the base forming paint (A2), and the value of the base layer formed by the base forming paint (A23) is the value of the base layer formed by the base forming paint (A2). It is a value between the base layer and the base layer formed by the base forming paint (A3).

<Repair painting method using the optimum base forming paint>
In the present invention, the spectral reflectance having the smallest absolute value of the difference from the average spectral reflectance of the colored base cured coating material to be repaired from among a plurality of different types of base forming paints having the above characteristics. A paint that forms a base layer having an average value is selected as an optimum base formation paint. Then, the optimum base forming paint is applied to the damaged portion of the coated body provided with the coloring base curing coating film, and the repair coloring base paint is applied on the formed base layer to perform repair coating. If there are multiple paints that form the underlying layer with the smallest spectral reflectance average value, the absolute value of the difference from the average spectral reflectance of the colored base cured coating to be repaired is the same, any of the applicable paints. Can be used.

First, the damaged portion of the coating film is scraped off, sanding is performed around the damaged portion as necessary, and then degreasing is performed as necessary. For line scratches, spot scratches, etc., the composition of the present invention can be directly applied to the degreased portion, and depending on the damage, the composition of the present invention can be applied after filling the scraped portion with various putties. .. The putty can be filled by a method known per se, such as by using a spatula. Examples of the putty include conventionally known sheet metal putty and resin putty, and examples thereof include vitrified cotton-based, acrylic resin-based, epoxy acrylate resin-based, unsaturated polyester resin-based, and urethane resin-based putty. When a putty is applied, it is preferable to dry the putty and then polish the putty surface. However, since the composition of the present invention has a good base hiding property, the polished surface may be rough.

As the coating of the base forming paint, a conventionally known coating method can be adopted, and spray coating is particularly preferable. The coating film thickness is preferably in the range of 50 to 500 μm in terms of dry film thickness.

The drying conditions are, for example, 5 to 80 ° C., preferably 10 to 60 ° C., and can be carried out for 10 to 120 minutes, particularly 20 to 90 minutes.

For the coating of the colored base paint for repair, a one-coat finish using only the colored base paint containing a metallic pigment (brilliant pigment) and / or the colored pigment, or the colored base paint and the clear paint are used. Conventionally known coatings such as 2-coat finishing can be mentioned.

As the colored base paint for repair, organic solvent-based, water-based, etc. topcoat paints normally used for repair can be used without particular limitation, and known painting means such as spray painting, electrostatic coating, brush coating, and roller coating can be used. Can be painted.

Drying after the coating of the colored base paint for repair is completed is not particularly limited, and may be in an uncured state when the top clear is reapplied. Generally, it is preferable to dry for 5 to 60 minutes under a temperature condition of, for example, 5 to 100 ° C. The film thickness varies depending on the coating color of the coloring base for repair, but generally, the dry film thickness is preferably in the range of 5 to 100 μm, particularly 10 to 60 μm.

Further, in the present invention, since the optimum base forming paint based on the colored base cured coating film to be repaired is selected, the target is even when the repair colored base paint is applied to a thickness less than the concealing film thickness. The appearance of the coating film can be obtained.

As the top clear paint to be applied on the colored base coating film for repair as needed, conventionally known ones can be used without particular limitation. For example, acrylic resin or fluorine resin containing a crosslinkable functional group such as a hydroxyl group can be used. A curable paint containing block polyisocyanate, polyisocyanate, melamine resin, etc. as a curing agent, or a lacquer paint containing cellulose acetate butyrate-modified acrylic resin as the main component can be preferably used as the main agent, and further, if necessary. It can contain additives for paints such as pigments, fibrous derivatives, additive resins, ultraviolet absorbers, light stabilizers, surface conditioners, and curing catalysts.

The top clear paint is preferably dried under temperature conditions of, for example, 20 to 100 ° C., preferably 40 to 100 ° C. for 5 to 60 minutes. The film thickness can be appropriately adjusted according to the condition of the surface to be coated, but generally, the dry film thickness is preferably in the range of 5 to 100 μm, particularly 10 to 60 μm.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to these examples. In addition, "part" and "%" in the following example mean "part by mass" and "mass%" respectively.

<Creation of test coating plate for measuring optical data of colored base topcoat coating>
Manufacturing example 1
A steel plate having a length of 300 mm and a width of 450 mm on which an intermediate coating paint was formed was used as a base material. A metallic coating color M (complete concealment film thickness of 12 μm) is applied to the base material so as to be 3 μm thicker than the complete concealment film thickness to form a metallic base coating film, and then a clear paint (Retan PG Eco HS Clear Q, (Manufactured by Kansai Paint Co., Ltd.) was spray-coated so that the dry film thickness was 50 μm and dried to obtain a laminated coating plate having a metallic coating color M.

Manufacturing example 2
A laminated coating plate of red mica coating color R was obtained in the same manner as in Production Example 1 except that the metallic coating color M was red mica coating color R in Production Example 1.

Manufacturing example 3
A laminated coating plate having a white mica coating color W was obtained in the same manner as in Production Example 1 except that the metallic coating color M was a white mica coating color W in Production Example 1.

Manufacturing example 4
A laminated coating plate of beige mica coating color BE was obtained in the same manner as in Production Example 1 except that the metallic coating color M was beige mica coating color BE in Production Example 1.

Production example 5
A laminated coating plate of blue mica coating color BL was obtained in the same manner as in Production Example 1 except that the metallic coating color M was blue mica coating color BL in Production Example 1.

Table 1 below shows the average value of the spectral reflectances of the laminated coating plates obtained in Production Examples 1 to 5 at an incident angle of 75 °, the maximum reflectance of 105 °, and the complete concealment film thickness of each colored base coating material.

(*) Average spectral reflectance The laminated coated plate obtained in Production Examples 1 to 5 above is subjected to a spectrophotometer CM512m3 (trade name, manufactured by Konica Minolta, a method of irradiating light rays from multiple directions in a ring shape). The spectral reflectance for each 10 nm was measured in the wavelength range of 400 to 700 nm under the condition of an incident angle of 75 °, and the average value of the obtained data was calculated.
(*) The ratio of the reflected light to the incident light in the direction of 105 °, with the direction of the positively reflected light as 0 ° when the light source is irradiated at the incident angle of 105 ° maximum reflectance 45 °, is determined by the spectrophotometer MA61B ( Using the product name (X-rite, colorimeter), the color temperature of the measurement light source was measured at about 3000 Kelvin, the set light source was the D65 light source, and the field of view was 10 degrees. The value was determined.

<Manufacturing paint for base formation>
Production example 6
30 parts of acrylic resin solution (Note 1) with 55% solid content, 6 parts of butyl acetate, 4 parts of methyl isobutyl ketone, 1.5 parts of pigment dispersant, 20 parts of titanium white, 0.03 part of carbon black, 30 parts of talc. , 5 parts of barium sulfate, 10 parts of zinc oxide, 0.1 part of dibutyltin dilaurate, 1.0 part of amide thickener (fatty acid amide, amide viscosity modifier, 20% active ingredient) are sequentially mixed, mixed and stirred. Then, it was dispersed for 30 minutes to obtain a main ingredient. Six parts of a polyisocyanate compound (“Sumijour N3390EA”, trade name, manufactured by Sumika Bayer Urethane Co., Ltd.) was mixed with 100 parts of the main ingredient component immediately before use to obtain a coating composition (A1) for forming a base. ..

(Note 1) Acrylic resin solution (1)
52 parts of butyl acetate was charged into the reaction vessel, and the temperature was raised to 110 ° C. with stirring. 15 parts of styrene, 10 parts of methyl methacrylate, 10 parts of n-butyl methacrylate, 20 parts of t-butyl methacrylate, 2-part of methacrylic acid. A monomer mixture consisting of 19 parts of ethylhexyl, 15 parts of 2-hydroxyethyl methacrylate, 10 parts of praxel FA-2D, and 1 part of acrylic acid and a monomer mixture of a polymerization initiator was prepared at 110 ° C. or lower over 3 hours using a dropping pump. And dropped at a constant rate. After the completion of the dropping, the temperature was maintained at 110 ° C. for 60 minutes, and stirring was continued. Then, as an additional catalyst, 0.5 part of azobisisobutyronitrile dissolved in 7 parts of butyl acetate was added dropwise at a constant rate over 60 minutes. Then, after the completion of the dropping, the temperature was maintained at 110 ° C. for 60 minutes to complete the reaction. The obtained hydroxyl group-containing acrylic resin solution was a uniform yellow transparent solution having a non-volatile content of 55%, the weight average molecular weight of the resin was 14,000, and the hydroxyl value was 81 mgKOH / g.

Production example 7
In 30 parts of an acrylic resin solution (Note 1) with a solid content of 55%, 6 parts of butyl acetate, 4 parts of methyl isobutyl ketone, 1.5 parts of pigment dispersant, 8 parts of titanium white, 0.1 part of carbon black, and 3 parts of talc.
0 part, barium sulfate 15 parts, zinc oxide 10 parts, dibutyltin dilaurate 0.1 parts, amide thickener (fatty acid amide, amide viscosity modifier, active ingredient 20%) 1.0 part are sequentially mixed and mixed. -Stirring and dispersion treatment for 30 minutes were carried out to obtain a main ingredient. Six parts of a polyisocyanate compound (“Sumijour N3390EA”, trade name, manufactured by Sumika Bayer Urethane Co., Ltd.) was mixed with 100 parts of the main ingredient component immediately before use to obtain a coating composition (A2) for forming a base. ..

Production Example 8
In 30 parts of an acrylic resin solution (Note 1) with a solid content of 55%, 6 parts of butyl acetate, 4 parts of methyl isobutyl ketone, 1.5 parts of pigment dispersant, 1 part of titanium white, 0.8 parts of carbon black, and 3 parts of talc.
0 parts, barium sulfate 20 parts, zinc oxide 10 parts, dibutyltin dilaurate 0.1 parts, amide thickener (fatty acid amide, amide viscosity modifier, active ingredient 20%) 1.0 part are sequentially mixed and mixed. -Stirring and dispersion treatment for 30 minutes were carried out to obtain a main ingredient. Six parts of a polyisocyanate compound (“Sumijour N3390EA”, trade name, manufactured by Sumika Bayer Urethane Co., Ltd.) was mixed with 100 parts of the main ingredient component immediately before use to obtain a coating composition (A3) for forming a base. ..

Manufacturing example 9
50 parts of the base-forming paint composition (A1) and 50 parts of the base-forming paint composition (A2) produced in Production Examples 6 and 7 were stirred and mixed to obtain a base-forming paint composition (A12).
Production Example 10
50 parts of the base-forming paint composition (A2) and 50 parts of the base-forming paint composition (A3) produced in Production Examples 7 and 8 were stirred and mixed to obtain a base-forming paint composition (A23).

Production Example 11 (for comparison)
In 30 parts of acrylic resin solution (Note 1) with 55% solid content, 6 parts of butyl acetate, 4 parts of methyl isobutyl ketone, 1.5 parts of pigment dispersant, 10 parts of titanium white, 0.1 part of carbon black, 50 parts of talc. , 15 parts of barium sulfate, 10 parts of zinc oxide, 0.1 part of dibutyltin dilaurate, 1.0 part of amide thickener (fatty acid amide, amide viscosity modifier, 20% active ingredient) are sequentially mixed, mixed and stirred. Then, it was dispersed for 30 minutes to obtain a main ingredient. Immediately before use, 5 parts of a polyisocyanate compound (“Sumijour N3390EA”, trade name, manufactured by Sumika Bayer Urethane Co., Ltd.) was mixed with 100 parts of the main ingredient to obtain a coating composition (B1) for forming a base. ..

Production Example 12 (for comparison)
In 30 parts of an acrylic resin solution (Note 1) with a solid content of 55%, 6 parts of butyl acetate, 4 parts of methyl isobutyl ketone, 1.5 parts of pigment dispersant, 10 parts of titanium white, 0.1 part of carbon black, and 5 parts of talc. , 0.1 part of dibutyltin dilaurate and 1.0 part of amide thickener (fatty acid amide, amide viscosity modifier, active ingredient 20%) are sequentially mixed, mixed and stirred, dispersed for 30 minutes, and the main ingredient. Ingredients were obtained. 11 parts of a polyisocyanate compound (“Sumijour N3390EA”, trade name, manufactured by Sumika Bayer Urethane Co., Ltd.) was mixed with 100 parts of the main ingredient component immediately before use to obtain a coating composition (B2) for forming a base. It was.

Production Example 13 (for comparison)
50 parts of the base-forming paint composition (A1) and 50 parts of the base-forming paint composition (B1) were stirred and mixed to obtain a base-forming paint composition (A1B1).

Production Example 14 (for comparison)
50 parts of the base-forming paint composition (A3) and 50 parts of the base-forming paint composition (B1) were stirred and mixed to obtain a base-forming paint composition (B1A3).

Production Example 15 (for comparison)
50 parts of the base-forming paint composition (A1) and 50 parts of the base-forming paint composition (B2) were stirred and mixed to obtain a base-forming paint composition (A1B2).

Production Example 16 (for comparison)
50 parts of the base-forming paint composition (A3) and 50 parts of the base-forming paint composition (B2) were stirred and mixed to obtain a base-forming paint composition (A3B2).

Production Example 17 (for comparison)
In 30 parts of an acrylic resin solution (Note 1) with a solid content of 55%, 6 parts of butyl acetate, 4 parts of methyl isobutyl ketone, 1.5 parts of pigment dispersant, 3 parts of titanium white, 2 parts of carbon black, 30 parts of talc, and sulfuric acid. 20 parts of barium, 10 parts of zinc oxide, 0.1 part of dibutyltin dilaurate, and 1.0 part of amide thickener (fatty acid amide, amide viscosity modifier, 20% active ingredient) are sequentially mixed, mixed and stirred. The dispersion treatment was carried out for 30 minutes to obtain the main ingredient. A polyisocyanate compound (“Sumijour N3390EA”, trade name, manufactured by Sumika Bayer Urethane Co., Ltd.) was mixed with 100 parts of the main ingredient component immediately before use to obtain a coating composition (B3) for forming a base. ..

Production Example 18 (for comparison)
50 parts of the base-forming paint composition (A2) and 50 parts of the base-forming paint composition (B3) were stirred and mixed to obtain a base-forming paint composition (A2B3).

In the base-forming coating composition produced in this example, the "resin component" is a solid content of the acrylic resin solution and a polyisocyanate compound which is a curing agent.

Table 2 below shows the brightness, the average spectral reflectance at an incident angle of 75 °, and the maximum reflectance of 105 ° of each of the base forming coating compositions obtained in Production Examples 6 to 18.

(*)brightness:
Each base-forming paint composition is coated on a tin plate with a concealing film thickness, dried at 60 ° C. for 20 minutes, and a clear paint (Retan PG Eco HS Clear Q, (trade name, manufactured by Kansai Paint Co., Ltd.)) is dried. The test coating plate obtained by spray coating so that the film thickness was 50 μm and dried at 60 ° C. for 20 minutes was L-valued under the condition of an incident angle of 45 ° using a spectrocolorimeter CM512m3 (trade name, manufactured by Konica Minolta). Was measured.
(*) Average spectral reflectance:
The test coating plate used for the measurement of brightness was measured with a spectrocolorimeter CM512m3 (trade name, manufactured by Konica Minolta) under the condition of an incident angle of 75 °, and the spectral reflectance was measured every 10 nm in the wavelength range of 400 to 700 nm. Then, the average value of the obtained data was calculated.
(*) 105 ° maximum reflectance:
The test coating plate used for measuring the brightness is reflected by 105 ° in the wavelength range of 400 to 700 nm under the condition of an incident angle of 45 ° using a spectrophotometer MA61B (trade name, manufactured by X-rite, colorimeter). The rate was measured and the highest reflectance was selected from the obtained data.

<Selection of the optimum base forming paint composition for each colored topcoat base and evaluation results of the actual repair coating board>
Example 1
The average value of the spectral reflectance of the metallic paint color M at an incident angle of 75 ° is 13. The base forming paints (A1), (A12), (A2), (A23), and (A3) according to the present invention were prepared. The base forming paint having the spectral reflectance average value closest to the spectral reflectance average value of the metallic paint color M is the base forming paint (A23).
Next, five laminated coating plates having the metallic coating color M obtained in Production Example 1 were prepared. One side of these five laminated coating plates is polished with sandpaper until the steel plate can be seen, and then dried to form a base forming coating composition (A1), (A12), (A2), (A23), (A3). Is spray-coated until the film has a completely concealed film thickness, dried at 60 ° C. for 20 minutes, and then each base-forming coating film is polished with No. 600 sandpaper, and metallic coating color A is applied thereto. , Spray coating is applied so that the drying film thickness is 9 μm (the complete concealing film thickness of the metallic coating color M is 12 μm) to form a metallic base coating film having a drying film thickness less than the concealing film thickness, and then drying at 60 ° C. for 10 minutes. After that, a clear paint (Retan PG Eco HS Clear Q, manufactured by Kansai Paint Co., Ltd.) is spray-applied so as to have a dry film thickness of 50 μm, and dried at 60 ° C. for 30 minutes to form a clear coating film and form various substrates. Using the paints (A1), (A12), (A2), (A23), and (A3), repair coating plates (M1) to (M5) having a common metallic color were obtained for the metallic coating color M and the clear coating. The prepared metallic color repair coating plates (M1) to (M5) were actually evaluated according to the following criteria. The results are shown in Table 3. The evaluation results of the metallic color repair coating plate obtained by actually painting with the base forming paint (A23) selected based on the average spectral reflectance are good, and the selection method of the present invention and the actual coating plate Correlation was found in. (See Production Example 22.).

Example 2
The average value of the spectral reflectance of the red mica paint color R at an incident angle of 75 ° is 17. The base forming paints (A1), (A12), (A2), (A23), and (A3) according to the present invention were prepared. The base-forming paint having the average spectral reflectance closest to the average spectral reflectance of the red mica coating color R is the base-forming paint (A2). Next, in Example 1 above, the red mica color R was used instead of the metallic paint color M, and the film thickness after polishing was 20 μm (the complete concealment film thickness of the red mica paint color R was 35 μm). In the same manner as in Example 1, various base forming paints (A1), (A12), (A2), (A23), and (A3) are used, and the red mica paint color R and the clear paint are common red mica color repairs. Coated plates (R1) to (R5) were obtained. The evaluation results of the red mica-colored repair coating plate obtained by actually painting with the base forming paint (A2) selected based on the average spectral reflectance are good, and the selection method of the present invention and the actual coating plate are good. A correlation was found with. (See Production Example 26.).

Example 3
The average value of the spectral reflectance of the white mica paint color W at an incident angle of 75 ° is 57.7. The base forming paints (A1), (A12), (A2), (A23), and (A3) according to the present invention were prepared. The base-forming paint having the spectral reflectance average value closest to the spectral reflectance average value of the white mica coating color W is the base-forming paint (A1). Next, in Example 1 above, white mica color W is used instead of the metallic paint color M, and the film thickness after polishing is 30 μm (the complete concealment film thickness of the white mica paint color W is 45 μm). In the same manner as in Example 1, using various base forming paints (A1), (A12), (A2), (A23), and (A3), white mica paint color W and clear paint are common white mica color repair. Coated plates (W1) to (W5) were obtained. The evaluation results of the white mica-colored repair coating plate obtained by actually painting with the base forming paint (A1) selected based on the average spectral reflectance are good, and the selection method of the present invention and the actual coating plate are good. A correlation was found with. (See Production Example 29).

Example 4
The average value of the spectral reflectance of the beige mica paint color BE at an incident angle of 75 ° is 32.0. The base forming paints (A1), (A12), (A2), (A23), and (A3) according to the present invention were prepared. The base-forming paint having the average spectral reflectance closest to the average spectral reflectance of the beige mica coating color BE is the base-forming paint (A12). Next, in Example 1 above, beige mica color BE is used instead of the metallic paint color M, and the film thickness after polishing is 25 μm (the complete concealment film thickness of the beige mica paint color BE is 40 μm). In the same manner as in Example 1, various base forming paints (A1), (A12), (A2), (A23), and (A3) are used, and the beige mica paint color BE and the clear paint are the common beige mica color BE. Repair coating plates (BE1) to (BE5) were obtained. The evaluation results of the beige mica-colored repair coating plate obtained by actually painting with the base forming paint (A12) selected based on the average spectral reflectance are good, and the selection method of the present invention and the actual coating plate are good. A correlation was found with. (See Production Example 35.).

Example 5
The average value of the spectral reflectance of the blue mica paint color BL at an incident angle of 75 ° is 3.0. The base forming paints (A1), (A12), (A2), (A23), and (A3) according to the present invention were prepared. The base-forming paint having the average spectral reflectance closest to the average spectral reflectance of the blue mica coating color BL is the base-forming paint (A3). Next, in Example 1, the blue mica coating color BL is used instead of the metallic coating color M, and the film thickness after polishing is 20 μm (the completely concealing film thickness of the blue mica coating color BL is 35 μm). In the same manner as in Example 1, various base forming paints (A1), (A12), (A2), (A23), and (A3) are used, and the blue mica paint color BL and the clear paint are common blue repair paint plates. (BL1) to (BL5) were obtained. The evaluation result of the blue repair coating plate obtained by actually painting with the base forming paint (A3) selected based on the average spectral reflectance is good, and the selection method of the present invention and the actual coating plate are used. Correlation was observed. (See Production Example 43.).

Comparative Example 1
In Example 2, the same as in Example 2 except that the base-forming paint (B1) having a larger amount of the extender pigment than the range of the present invention is used instead of the base-forming paint (A2).
Using various base-forming paints (A1), (A1B1), (B1), (B1A3), and (A3), a red mica paint color R and a common red mica paint for clear paint were obtained. The base forming paint having the spectral reflectance average value closest to the spectral reflectance average value of the red mica coating color R is the base forming paint (B1). However, when the repair coating plate obtained by actually painting with the base forming paint (B1) was evaluated, the finished appearance was Δ rank and the adhesiveness was × rank. (See Production Example 46).

Comparative Example 2
In the second embodiment, the same as in the second embodiment except that the base forming paint B2 in which the blending amount of the extender pigment is smaller than the range of the present invention is used instead of the base forming paint A2.
Using various base-forming paints (A1), (A1B2), (B2), (B2A3), and (A3), a red mica paint color R and a common red mica paint for clear paint were obtained. The base forming paint having the spectral reflectance average value closest to the spectral reflectance average value of the red mica coating color R is the base forming paint (B2). However, when the repair coating plate obtained by actually painting with the base forming paint (B2) was evaluated, the polishability was x rank. (See Production Example 51).

Comparative Example 3
In the fifth embodiment, the same as in the fifth embodiment except that the base forming paint B3 having a black pigment blending amount larger than the range of the present invention is used instead of the base forming paint A3.
Using various base forming paints (A1), (A1A2), (A2), (A2B3), and (B3), a common blue repair coating plate was obtained for the blue mica coating color BL and the clear coating. The base forming paint having the spectral reflectance average value closest to the spectral reflectance average value of the blue mica coating color BL is the base forming paint (B3).

However, when the repair coating plate obtained by actually painting with the base forming paint (B3) was evaluated, the degree of scale was x rank. (See Production Example 58).

Comparative Example 4
The base-forming paints (A1), (A12), (A2), (A23), and (A3) according to the present invention are prepared, and the incident angle is 45 ° instead of the spectral reflectance average value at 75 °. Based on the value of the maximum reflectance of 105 °, a base forming paint suitable for each coloring base paint was selected. The results are shown in Table 4. When the value of the maximum reflectance of 105 ° was used, good results were obtained for the white mica coating color W and the blue mica coating color BL even in the repair coating plate obtained by actually painting, and a correlation was observed. However, with respect to the metallic paint color M, the red mica paint color R, and the beige mica paint color BE, the repair paint board actually painted had a scale. (See Production Examples 23, 28, 36).

(*) Degree of coating film for base formation The extent to which the coating film for base formation can be seen through the clear coating film and the coloring base coating film of each repair coating plate was visually evaluated according to the following criteria.
〇: The paint color of the base film is not visible at all, and the difference between the unrepaired part and the repaired part cannot be confirmed.
Δ: The coloring base coating film is transparent, and the coating color of the base film forming coating film can be seen faintly.
X: The coloring base coating film is transparent and the coating color of the coating film for forming the base is clearly visible (*) Finished appearance The appearance of each repair coating plate was visually evaluated according to the following criteria.
◎: The glossiness and smoothness of the coated surface are very good, and neither suction nor plastic suff marks are observed.
◯: Good gloss and smoothness on the coated surface, no suction or traces of plastic suff, Δ: Slightly poor gloss and smoothness on the coated surface, no traces of suction or plastic suff. ,
X: The glossiness and smoothness of the coated surface are poor, and either suction or Prasaf marks are observed. (*) Adhesiveness For each repair coating plate, a grid test conforming to JIS K5600 was performed on the portion coated with the coating film for forming the base. Specifically, 100 cuts that reach the material in a grid pattern are made on the coating film at intervals of 2 mm in the vertical and horizontal directions, and an adhesive tape having an adhesive force (120 gf / 10 mm) is attached. Then, the adhesive tape was instantly peeled off, and the number of coating film pieces that were peeled off and adhered to the adhesive tape was examined and evaluated according to the following criteria.
◯: No peeling between the undercoat coating and the metallic base coating,
Δ: The number of peels between the undercoat coating film and the metallic base coating film is less than 10%.
X: The number of peelings between the undercoat coating film and the metallic base coating film is 10% or more.
(*) Polishability The polishing feeling when the surface of the coating film for forming various substrates was polished with P600 paper was evaluated.
◎: Very good,
○: Good,
△: There is some entanglement,
×: There is considerable entanglement.

Claims (7)

A paint for forming a base layer provided under the colored base coating film by the colored base paint for repair for repairing a damaged part of the coated body provided with the colored base cured coating film.
For 100 parts by mass of resin component
45 to 110 parts by mass of white pigment and 20 to 300 parts by mass of extender pigment,
Base forming paint (A1), including
For 100 parts by mass of resin component
White pigment 10 parts by mass or more and less than 45 parts by mass,
Substrate forming paint (A2) containing 20 to 300 parts by mass of extender pigment and 0.1 to 5.0 parts by mass of black pigment,
1 part by mass or more of white pigment and less than 10 parts by mass with respect to 100 parts by mass of the resin component.
A coloring base in the repair target from among a plurality of different types of base-forming paint groups including a base-forming paint (A3) containing 20 to 300 parts by mass of an extender pigment and 0.1 to 5.0 parts by mass of a black pigment. a method for selecting a base-forming coating material, characterized in that selecting a coating material for forming an underlayer absolute value with the smallest spectral reflectance average value of the difference between the average value of the spectral reflectance of the cured coating film ,
The method in which the average value of the spectral reflectances of the colored base cured coating film and the underlying layer is the average value of the reflectances measured at intervals of 10 nm in the wavelength range of 400 to 700 nm and 2.0% or more . The selection method according to claim 1, wherein the base forming paints (A1) to (A3) are two-component reaction-curable paints. A plurality of different types of base-forming paint groups can be obtained by mixing two or more of the base-forming paints (A1) to (A3) in addition to the base-forming paints (A1) to (A3). The selection method according to claim 1 or 2, further comprising a base forming paint (An). The base-forming paint (An) is a mixture (A12) of the base-forming paint (A1) and the base-forming paint (A2), and a mixture (A23) of the base-forming paint (A2) and the base-forming paint (A3). The selection method according to claim 3, wherein the base-forming paint group comprises five types of paint groups. The selection method according to any one of claims 1 to 4 , wherein the spectral reflectance of the colored base cured coating film and the underlying layer is determined by a method of irradiating light rays from multiple directions in an annular shape. The selection method according to any one of claims 1 to 5 , wherein the spectral reflectance of the colored base cured coating film and the underlying layer is performed within a range of an incident angle of light rays of 10 to 90 °. A base forming paint selected by the selection method according to any one of claims 1 to 6 is applied to a damaged portion of a coated body provided with a coloring base cured coating film, and the base layer is formed. A repair painting method characterized by painting a colored base paint for repair.