JPH02126972A - Method for repairing coating film - Google Patents

Abstract

PURPOSE:To form a highly-finished lustrous coating film having an appearance of thickness and depth by applying an acrylic urethane coating which is then dried and polished, then applying a colored top coat, and applying a specified finishing top coat to repair a coating film. CONSTITUTION:When the coating film on an automobile is repaired, an acrylic urethane coating is applied directly or through a primer surfacer coating film which has been polished in the finish coating stage, and dried to form a first overcoating film. The first overcoating film is polished, and a specified colored top coat is applied. Before or after the second overcoating film is cured, a finishing top coat such as an acrylic lacquer contg. the pigment corresponding to 0-90% of the pigment contained in the solid resin in the colored top coat is applied. By this method, a highly-finished lustrous coating film having an appearance of thickness and depth is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for repairing a paint film, and more particularly, to a method for repairing a paint film that can form a high-quality finished paint film that is particularly suitable for repairing automobiles.

[Conventional technology and problem 1] In recent years, automobile manufacturers have increasingly advanced the quality of their paints, and the number of high-finish paint films with a durable feel, gloss, and depth is increasing.

On the other hand, conventional paint film repair specifications generally include primer surfer painting, polishing, and topcoating with one type of paint.
Or, it is only top coated with one type of paint.
Although the finish quality of new car paint films has improved, conventional repair methods are currently impractical due to the noticeable poor quality of the finish.

For this reason, it has been desired to establish a repair method that can form a high-quality finished coating.

[Disclosure of the Invention] Therefore, the present inventors have intensively studied a repair method that can form a high-grade finish coating film that can be applied to the repair of high-grade finished cars, and as a result, they have arrived at the present invention. That is, the present invention provides a method for repairing a paint film in which a top coat is applied with or without a primer surfacer paint film, and the top coat step includes fa) applying an acrylic urethane paint, drying it, and applying a first top coat. Step of forming a film, [BL Step of polishing the first top layer coating film, (CL) Applying a color-determined colored top coat paint on the polished first top layer coating film, and applying a second top layer coating film. (d) on the second top coat coating film, in the colored top coat paint,
The present invention relates to a method for repairing a coating film, which includes the step of applying a finishing top coat having a pigment content ratio of 0 to 90% relative to the resin solid content.

According to the method of the present invention, it is possible to form a coating film with either a high-quality finish such as an enamel finish or a metallic finish.

The main processes of standard repair painting are: ■Paint removal, base polishing, ■Feather etching, ■Blimmer painting, ■Sheet metal putty and polyester putty application and polishing, ■Blimmer Surf Acer painting and polishing, ■Final coating, ■This includes polishing and finishing, and some steps may be omitted depending on the situation, such as the degree of scratches.

The present invention provides a repair method with a high-quality finish by adding various studies to the top coating process of the above-mentioned repair painting processes.

The first step (al) of the top coating process in the present invention is to apply an acrylic urethane paint with or without a polished primer surfer paint film and dry it to form a first top layer paint film. The above-mentioned acrylic urethane paint mainly contains a hydroxyl group-containing acrylic resin, a polyisocyanate compound, and a pigment.

The above-mentioned hydroxyl group-containing acrylic resin is a resin obtained by copolymerizing a monomer component whose main components are a hydroxyl group-containing polymerizable unsaturated monomer and an acrylic monomer copolymerizable with the hydroxyl group-containing polymerizable monomer. Saturated monomers include hydroxy group-containing monomers such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate.
Meth)alkyl acrylate (C, ~,.) ester; commercially available product is Plaxel FA-1 (monomer obtained by adding 1 mole of ε-caprolactone to 1 mole of 2-hydroxyethyl acrylate), a product of Daicel Chemical Industry ■. , Praxel FM-1, Praxel FM-3, Praxel FM
-5 (ε for 1 mole of 2-hydroxyethyl methacrylate)
- Monomer to which 1 mol, 3 mol, and 5 mol of caprolactone were added, respectively), TONE M-100, a product of Union Carbide (USA) (monomer to which 2 mol of ε-caprolactone was added to 1 mol of 2-hydroxyethyl acrylate) ), etc., adducts of 1 mol of hydroxyl group-containing (meth)acrylic acid ester and 1 to 5 mols of lactones, and the like can be used. Examples of acrylic monomers copolymerizable with saturated monomers include 1, for example, methyl (
meth)acrylate, ethyl(meth)acrylate,
Examples include propyl (meth)acrylate butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and other esters of acrylic acid or methacrylic acid with monohydric alcohols having 1 to 20 carbon atoms. (meth)acrylate, 1.
Acrylic acid or methacrylic acid such as 6-hexanone (meth)acrylate, trimethylolpropane di(meth)acrylate, allyl (meth)acrylate, trimethylolpropane tri(meth)acrylate and 2 to 2 carbon atoms
Compounds having two or more polymerizable double bonds in one molecule obtained by reacting with 16 dihydric or higher alcohols; monocarboxylic acids such as (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, etc. α, β-ethylenically unsaturated carboxylic acids such as dicarboxylic acids or half esters of dicarboxylic acids: N-propoxymethyl (meth)acrylamide, N-
Butoxymethyl (meth)acrylamide, glycidyl (
Meth)acrylate, vinyltoluene, styrene, dimethylaminoethyl acrylate, acrylic acid amide, vinyl acetate, etc. can also be used.

The hydroxyl group-containing resin can be obtained by copolymerizing the above-mentioned monomer components in the presence of an azo polymerization initiator or a peroxide polymerization initiator, but other monomer components such as Toagosei Co., Ltd. ■Product, AA-
2, AA-6゜AB-2, AB-6, etc., having a polymerizable unsaturated group at one end of the molecule and having a molecular weight of 2000 to 1500
Copolymerization of 0.0 acrylic macromonomer or graft copolymerization of cellulose acetate butyrate with the above monomer components can also be used.

These hydroxyl group-containing acrylic resins have a hydroxyl value of 20 to 2.
00, and the number average molecular weight is preferably within the range of 15,000 to 50,000.

Further, the polyisocyanate compound is a compound having two or more free isocyanate groups in one molecule, and specifically, tolylene diisocyanate, 4.4'-
diphenylmethane diisocyanate, xylylene diisocyanate, metaxylylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate,
hydrogenated 4.4'-diphenylmethane diisocyanate,
Hydrogenated tolylene diisocyanate, inphorone diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, adduct of tolylene diisocyanate (3 mol) and trimethylolpropane (1 mol), polymer of tolylene diisocyanate, hexamethylene diisocyanate (3 mol) and trimethylolpropane (1 mol), reaction product of hexamethylene diisocyanate and water, adduct of xylylene diisocyanate (3 mol) and trimethylolpropane (1 mol), tolylene diisocyanate (3 mol) and hexamethylene diisocyanate (2 mol), etc. One or more types selected from adducts of xylylene diisocyanate and water, which have excellent weather resistance, etc., can be used. Adduct of diisocyanate and trimethylolpropane, adduct of tolylene diisocyanate and hexamethylene diisocyanate, inphorone diisocyanate, hexamethylene diisocyanate,
Non-yellowing types such as lysine diisocyanate are preferred.

The mixing ratio of the hydroxyl group-containing acrylic resin and the polyisocyanate compound is 0.5 to 2.5, especially 0.
．． A range of 7 to 2.0 is preferable, and since the same components may react at room temperature and crosslink and harden, it is preferable to separate them in advance and mix them immediately before use.

In addition, as pigments, coloring pigments and extender pigments that are commonly used in the field of paints can be used, and these pigments have a pigment rating of 70 to 170 PI (R, and even 100 to 150 PI).
Preferably the pigment is within the range of HH 70PHR
If it is less than 170 PIIR, the abrasiveness of the resulting first top layer coating film will be poor; on the other hand, if it exceeds 170 PIIR, the suction of the first top layer coating film will be large, making it impossible to obtain a high-finish overall coating film.

Further, it is preferable that the degree of dispersion of the pigment is within the range of 30 to 50 microns in terms of polishability and gloss of the final coating film.

In addition to the above-mentioned components, the acrylic urethane paint forming the first layer coating film contains a curing accelerator such as dibutyltin (2-
ethylhexoate), tin octenoate, di-n-butyltin dilaurate, tri-n-butyltin chloride, tetra-n
-Butyltin etc. are preferable, and the amount of catalyst added is 0.01-
1° part by weight is preferred, especially 0.05 to 5 parts by weight.

In addition, this acrylic urethane paint is quick-drying from the viewpoint of painting workability, that is, it dries at 20°C for 3 hours.
If the temperature is 60° C., it is preferable that the material be cured by drying for 20 minutes before the next step of polishing can be performed.

The step (bl) in the present invention is a step of polishing the coating film obtained by the above step (a), and is usually 30 to 80 microns, preferably 40 microns, which is obtained by step fa).
A coating film with a thickness of about 60 microns is dry-sanded and/or wet-sanded using a sander, hand sanding, or the like. As the polishing vapor, use #600 or a vapor finer than #600, and it is preferable to polish it smoothly from the viewpoint of finishing quality. Since the absorption of paint applied to the surface is suppressed, it is easier to obtain a glossy finish and a smooth coating surface.

In the present invention, (as a CL step), a colored top coat of a determined color is applied on top of the polished first layer of the top coat that has undergone the BL step to form a second top layer.
As the layer paint, any of acrylic lacquer, nitrocellulose or cellulose acetate butyrate modified acrylic lacquer, and acrylic urethane can be used. This is preferable from the viewpoint of membrane performance.

In addition, the pigment content can be used as appropriate depending on the desired coating color.
Usually, the pigment composition is the same or similar to the paint color around the repaired area.

(The CL process is not particularly limited, but if you look at it in detail, it is usually: (1) a discard blowing process that blends the paint into the first JI topcoat film.

It consists of three steps: ■ Color deciding process, in which the paint is painted without any scratches, and ■ Surface adjustment process, in which the paint is applied evenly to the skin while observing the painted surface.
It is painted wet, and between ■-〇 is wet-on-wet or after the ■ process to further improve the finished appearance.
After curing the coating film and then polishing the cured coating film, the step (2) may be performed (or, after the step (2), the step (2) may be performed without curing and polishing.

In each step of ■ to ■, usually lO to about 30 microns, preferably about 15 to 30 microns, the sum of ■ to ■ is 30 to 10
0 micron, preferably 45-90 micron, more preferably 60-75 micron (for enamel finishing)
(dry film thickness).

In the present invention, in the fdl step, after the step (C), a finishing top coat is applied on the uncured or hardened second layer top coat.

As a finishing top coat, [in the colored top @ paint used in the CL process, the pigment content ratio to resin solid content is 0]
Any of acrylic lacquer, nitrocellulose or cellulose acetate butyrate modified acrylic lacquer, and acrylic urethane having a pigment content ratio of ~50% can be used. It is preferable from the point of view of coating performance, etc., and the pigment content ratio of the finishing top coat is 0 to 90% of the pigment content ratio of the second layer paint used in the fc) step, preferably 0 to 60%. %, that is, it needs to be a clear paint or a low pigment concentration paint. In the case of a low pigment concentration paint, a paint of the same color or similar color to the paint for the second layer coating is usually mixed with a clear paint to reduce the pigment concentration. If the pigment content ratio of the finishing top coat exceeds 0% of the pigment content ratio of the second layer paint, the overall paint film that is finally obtained will not have sufficient improvement in durability, gloss, and depth. The undesirable film thickness (dry film) of the finishing top coat is preferably in the range of 30 to 90 microns, more preferably 50 to 70 microns in the case of metallic finishes, and 10 to 90 microns, and more preferably 15 to 15 microns in the case of enamel finishes.
A range of 70 microns is preferred.

In the present invention, by including the above and the above-mentioned steps (a) to (d) as the top coating step in the paint film repair method, a high-quality finish paint film with a solid feel, gloss, and depth can be obtained. A repair method is provided which is particularly applicable to the repair of high-grade paint films on automobiles.

[Example] Hereinafter, the present invention will be described in more detail with reference to Examples. Note that the present invention is not limited only to the examples.

Example 1 150 microns of polyester putty was applied onto a polished mild steel plate, and after drying at room temperature (20°C) for 1 hour, #120
6 Next, 50 microns of lacquer-based Brimer Surfacer was applied on this, dried at room temperature (20°C) for 1 hour, and then polished with #400 sandpaper to obtain the test material. And so.

The above test material was coated with 50 microns of Rethane PG First Coat (manufactured by Kansai Paint Co., Ltd., acrylic urethane paint, white) as the first layer of paint, dried at 60°C for 20 minutes, and then polished with #600 sandpaper. I did it. Next, 50 microns (dry film thickness) of Rethane PG80 Metalitta Color (manufactured by Kansai Paint Co., Ltd., quick-drying acrylic urethane paint, silver metallic color) was applied on the first layer of the polished top coat, and the film was left at room temperature for 3 minutes. After leaving to stand still, rethane PG-80
Quartz Clear 2 (manufactured by Kansai Paint Co., Ltd., quick-drying acrylic urethane paint clear) wet on wet 6
A coated plate for testing was prepared by applying 0 micron (dry film thickness) coating and baking at 60°C for 30 minutes.

Example 2 A test material similar to that used in Example 1 was coated with 50 microns of Rethane PG First Coat as the first top coat, dried at room temperature (20°C) for 3 hours, and then sanded with #600 sandpaper. Polishing was performed. Next, 70 microns (dry film thickness) of Rethane PG60 White (manufactured by Kansai Paint Co., Ltd., acrylic urethane paint enamel, white) was applied on the polished first layer of top coat, and after standing at room temperature for 3 minutes, Rethane PG60 White was applied. Rethane PG-60 Clear (manufactured by Kansai Paint Co., Ltd., Acrylic Finishing paint mixed with urethane paint (clear) was applied wet-on-wet to a thickness of 25 microns.70
A test coated plate was prepared by drying at ℃ for 30 minutes.

Example 3 In Example 2, instead of coating 70 microns of Rethane PG60 white on the first layer coating, Rethane PG60
Paint white 50 microns (dry film thickness) at 60℃ 3
After baking for 0 minutes, the same procedure as in Example 2 was carried out except that it was polished with #1000 sandpaper and then sprayed with Rethane PG60 White to a thickness of 25 microns (dry film thickness).

Example 4 The same procedure as in Example 1 was carried out except that the rethane PG first coat coating was polished with #400 sandpaper.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the rethane PG first coat was not applied.

Comparative Example 2 The same procedure as in Example 1 was carried out except that a 50 micron (dry film thickness) lacquer-based Brimer Surfacer was applied instead of the rethane PG first coat.

Comparative Example 3 The same procedure as in Example 2 was carried out except that the rethane PG first coat was not applied.

Tests were conducted on the test coated plates obtained in Examples 1 to 4i5 and Comparative Examples 1 to 3 above. The test results are shown in Table 1 below.

The tests in Table 1 were conducted according to the following method.

The degree of fleshiness of the coating film was visually evaluated under a fluorescent lamp with an illuminance of 1000 lux.

($2) Gloss Visually evaluate the gloss of the paint film under a fluorescent lamp with an illuminance of 1000 lux.

Also, the glossy needle has a 20° mirror shine. Reflectance (20° gross) is also measured. Ru.

(*3) Skin: Visually evaluate the smoothness of the coating film under a fluorescent lamp with an illuminance of 1000 lux.

Further, the degree of sharpness of the coating film is measured using a sharpness gloss meter P GD-IV sold by Japan Color Research Institute.

Note that visual evaluation in (*1), ($2), and (*3) was performed according to the following evaluation criteria.

Claims (1)

[Scope of Claims] 1. A method for repairing a coating in which a top coat is applied with or without a primer surfacer coating,
The top coating process includes: (a) a step of applying an acrylic urethane paint and drying it to form a first top layer coating; (b) a step of polishing the first top layer coating; (c) a step of polishing the first top layer coating; A step of applying a colored top coat with a determined color on the first top layer paint film to form a second top coat film; (d) on the second top coat film, in the colored top coat paint;
A method for repairing a coating film, comprising the step of applying a finishing top coat having a pigment content ratio of 0 to 90% of the pigment content ratio to the resin solid content. 2. Step (c) is to apply a color-determined colored topcoat on the polished first-layer paint film, cure it, then polish the cured paint film, and then apply the color-determined color on this paint film. 2. The method for repairing a paint film according to claim 1, which is a step of applying a colored top coat. 3. The method for repairing a coating film according to claim 1 or 2, characterized in that the first top coat coating film is polished with #600 paper or a paper finer than #600. 4. The method for repairing a paint film according to claim 1, 2 or 3, wherein both the colored top coat paint for forming the second top layer paint film and the finishing top coat paint are acrylic urethane paints.