JP2667886B2 - Repair method of coating film - Google Patents

Description

The present invention relates to a method for repairing a coating film, and more particularly, to a method for repairing a coating film capable of forming a high-grade finish coating film particularly suitable for repairing automobiles.

[Prior art and problems] In recent years, each automobile manufacturer has been upgrading the quality of painting, and the number of highly finished coating films with a feeling of durability, gloss, and depth has been increasing.

On the other hand, the conventional specifications for repairing coating films are generally primer surfacer coating-polishing-overcoating with one type of paint or overcoating with one type of paint, to improve the finish of new car coatings. However, the conventional repair method is inferior in the finish and is not practical in practice.

For this reason, establishment of a repair method capable of forming a high-grade finish coating film has been desired.

DISCLOSURE OF THE INVENTION Accordingly, the present inventors have intensively studied a repair method capable of forming a high-grade finish coating film that can also be applied to repair of a high-grade finish vehicle, and as a result, have reached the present invention. That is, the present invention provides a method for repairing a coating film in which a top coat is applied with or without a primer surfacer coating film, wherein (a) an acrylic urethane paint containing a pigment in an amount of 70 to 170 PHR is applied as a top coating process. And then drying to form a topcoat first-layer coating film, (b) a step of polishing the topcoat first-layer coating film, and (c) a colored topcoat that has been color-coded on the polished topcoat first-layer coating film. A step of applying a paint to form a top coat second layer coating film, (d) on the top coat second layer coating film, in the colored top coat paint,
The present invention relates to a method for repairing a coating film, which comprises a step of applying a finish topcoat having a pigment content ratio of 0 to 90% of a resin solid content.

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

The main processes of standard repair painting are coating peeling, substrate polishing, feather edging, primer coating, sheet metal putty and polyester putty attaching and polishing, primer surfacer painting, polishing, top coat painting, polishing finish, etc. Some steps may be omitted depending on circumstances such as the degree.

The present invention provides a high-quality finishing repair method by conducting various studies on the topcoat painting step of the above-mentioned repair painting steps.

The first step (a) of the overcoating step in the present invention comprises:
An acrylic urethane paint is applied with or without a polished primer surfacer coating film, and dried to form a top coat first layer coating film. The acrylic urethane paint contains a hydroxyl group-containing acrylic resin, a polyisocyanate compound and a pigment as main components.

The hydroxyl group-containing acrylic resin is a resin obtained by copolymerizing a monomer component mainly composed of a hydroxyl group-containing polymerizable unsaturated monomer and an acrylic monomer copolymerizable therewith, and is a hydroxyl group-containing polymerizable unsaturated resin. Examples of the saturated monomer include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and other hydroxy group-containing alkyl (meth) acrylates ( _C2-10 ) esters; commercially available products of Daicel Chemical Industries, Ltd. Certain Praxel FA-1 (a monomer obtained by adding 1 mol of ε-caprolactone to 1 mol of 2-hydroxyethyl acrylate), Praxel FM-1, Praxel FM-3, Praxel FM-5
(Monomer obtained by adding 1 mol, 3 mol, and 5 mol of ε-caprolactone to 1 mol of 2-hydroxyethyl methacrylate), TONE M-100 (2-hydroxyethyl acrylate), a product of Union Carbide (US) 1
Monomer in which 2 mol of ε-caprolactone is added to the mol)
One or two or more selected from adducts of 1 mol of a hydroxyl group-containing (meth) acrylate and 1 to 5 mol of a lactone can be used. Examples of the acrylic monomer copolymerizable with the monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and 2- (meth) acrylate.
Examples thereof include esterified products of acrylic acid or methacrylic acid such as ethylhexyl (meth) acrylate and a monohydric alcohol having 1 to 20 carbon atoms. In addition to these, ethylene glycol di (meth) acrylate and 1,6-hexanedi (meth) acrylate By reacting acrylic acid or methacrylic acid such as acrylate, trimethylolpropane di (meth) acrylate, allyl (meth) acrylate, tri (meth) acrylate and trimethylolpropane with a dihydric or higher alcohol having 2 to 16 carbon atoms Compounds having two or more polymerizable double bonds in one molecule; monocarboxylic acids such as (meth) acrylic acid, dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; and half-esterified products of dicarboxylic acids. α, β-ethylenically unsaturated carboxylic acid; N-propoxymethyl (meth) acrylamide , N-butoxymethyl (meth) acrylamide, glycidyl (meth) acrylate, vinyl toluene, styrene, dimethylaminoethyl acrylate, acrylamide, vinyl acetate and the like can also be used.

Hydroxyl group-containing resin is obtained by copolymerizing the above-mentioned monomer component by a usual method in the presence of an azo-based polymerization initiator or a peroxide-based polymerization initiator.
As a monomer component, for example, a product of Toa Gosei Chemical Co., Ltd.,
AA-2, AA-6, AB-2, AB-6 and other acrylic macromonomers having a molecular weight of 2000 to 15,000 having a polymerizable unsaturated group at one end of the molecule are copolymerized, or cellulose acetate butyrate is used. Those obtained by graft copolymerization with the monomer component can also be used.

These hydroxyl-containing acrylic resins have a hydroxyl value of 20 to 20.
It is preferable that the number average molecular weight is in the range of 5,000 to 50,000.

In addition, the polyisocyanate compound contains 2 per molecule.
A compound having at least one free isocyanate group, specifically, tolylene diisocyanate, 4,4′-
Diphenylmethane diisocyanate, xylylene diisocyanate, meta-xylylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate,
Hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate,
Dimer acid diisocyanate, adduct of tolylene diisocyanate (3 mol) with trimethylolpropane (1 mol), polymer of tolylene diisocyanate, adduct of hexamethylene diisocyanate (3 mol) with trimethylolpropane (1 mol) Reaction product of hexamethylene diisocyanate and water, adduct of xylylene diisocyanate (3 mol) and trimethylolpropane (1 mol), adduct of tolylene diisocyanate (3 mol) and hexamethylene diisocyanate (2 mol) One or more selected from the group consisting of a reaction product of xylene diisocyanate and water, an adduct of xylylene diisocyanate and trimethylolpropane, and a tolylene diisocyanate and hexamethylene diisocyanate having excellent weather resistance. Soshi Adducts of sulfonates, isophorone diisocyanate, hexamethylene diisocyanate, are non-yellowing type, such as lysine diisocyanate preferable.

The compounding ratio of the hydroxyl group-containing acrylic resin to the polyisocyanate compound is 0.5 to 2.5, particularly 0.7 to 500, based on the hydroxyl group / isocyanate group (molar ratio) contained therein.
A range of 2.0 is preferred. Also, since both components may react at room temperature to cause crosslinking and curing, it is preferable to separate them in advance and mix them immediately before use.

As the pigment, coloring pigments and extenders commonly used in the field of paints can be used.These pigments are contained in an amount of 70 to 170 PHR, and more preferably 100 to 150 PHR.
Is preferably within the range. If the pigment is less than 70 PHR, the resulting top coat first layer coating film has poor abrasion properties, while 170 PHR
When it exceeds, the suction of the top coat first layer coating film becomes large,
A high-quality coating film cannot be obtained as an overall coating film. In addition, the degree of dispersion of the pigment is 50 microns or less, and 30 to
It is preferable that the thickness be within the range of 50 microns from the viewpoints of abrasion and glossiness of the final coating film.

In addition to the above-mentioned components, the acrylic urethane coating material for forming the first-layer coating film may be, for example, dibutyltin (2
-Ethylhexoate), tin octenoate, di-n-butyltin dilaurylate, tri-n-butyltin chloride, tetra-n-butyltin, etc. are preferable, and the catalyst is added in an amount of 0.01 to 100 parts by weight of the hydroxyl group-containing acrylic resin solid content. 10 parts by weight, especially 0.05 to 5 parts by weight, is preferred.

Also, acrylic urethane paint is a quick-drying type from the viewpoint of coating workability, that is, drying at 20 ° C for 3 hours, 60 ° C.
In that case, it is preferable that the resin be cured by the drying for 20 minutes before polishing in the next step can be performed.

The step (b) in the present invention is a step of polishing the coating film obtained in the step (a), and is usually 30 to 80 microns, preferably 40 to 60, obtained in the step (a).
A film having a film thickness of about a micron is ground and / or water-polished by sanding, hand polishing, or the like. As the polishing paper, # 600 or a finer paper than # 600 is used, and it is preferable to polish the surface smoothly in terms of finishability. By interposing this polished first-layer top coat, it is possible to prevent the paint to be applied onto the top coat, so that a glossy finish can be easily obtained, and a smooth coated skin can be easily obtained. .

In the present invention, a colored topcoat paint having a predetermined color is applied onto the polished topcoat first-layer paint film subjected to step (b) as step (c) to form a topcoat second-layer paint film. Acrylic lacquer, nitrocellulose or cellulose acetate butyrate-modified acrylic lacquer, or acrylic urethane can be used as the coating for the second layer of the top coat. As the resin component, the resin composition of the acrylic urethane paint described in the step (a) can be used. This is preferred from the viewpoint of coating film performance and the like.

The pigment component may be appropriately used according to the desired coating color, and is usually a pigment composition having the same or similar color as the coating color around the repaired part.

The step (c) is not particularly limited, but in detail, it is usually a waste blowing step in which the paint is applied to the first top coat, a color-determining step in which the paint is applied without scratches, and a coating surface. It consists of three steps, the process of adjusting the paint surface to apply it evenly to the skin while looking at it.
Painted wet, -between wet-on-wet or after the process to further improve the finished appearance,
The step of curing the coating film and then polishing the cured coating film may be performed, or the step of curing and polishing without polishing may be performed after the step.

In each step of ~ 10 ~ 30 microns, preferably about 15 ~ 30 microns, the sum of ~ 30 ~ 100 microns, preferably 45 ~ 90 microns, in the case of enamel finish, more preferably 60 ~ 75 microns (dry The film thickness is applied.

In the present invention, as the step (d), after the step (c),
A finish topcoat is applied over the uncured or cured topcoat second layer coating.

As the finish topcoat, any of acrylic lacquer, nitrocellulose or cellulose acetate butyrate-modified acrylic lacquer, and acrylic urethane can be used. As the resin component, the resin composition described in the acrylic urethane paint in step (a) must be used. Is preferable from the viewpoint of coating film performance. In addition, the pigment content of the finish top coat is 0 to 90%, preferably 0 to 60%, of the pigment content of the second layer coating used in the step (c).
It must be a clear paint or a low pigment concentration paint. In the case of a low pigment concentration paint, a paint having the same or similar color as the paint for the second layer coating film is mixed with a clear paint to reduce the pigment concentration. The pigment ratio of the finish coating is the pigment ratio of the pigment for the second layer coating film.
If it exceeds 90%, it is not preferable because improvement in the feeling of stickiness, gloss and depth is not sufficiently achieved in the finally obtained total coating film. The film thickness (dry film) of the finish coat is preferably in the range of 30 to 90 microns, more preferably 50 to 70 microns in the case of metallic finish, and in the range of 10 to 90 microns, more preferably 15 to 70 microns in the case of enamel finish. Is preferred.

In the present invention, by having the above-mentioned steps (a) to (d) as the top-coating step in the method for repairing a coating film, a high-quality finish coating film with a high finish having a feeling of meat retention, gloss, and depth. The present invention provides a repair method capable of forming a coating film, and is particularly applicable to repair of a high-grade coating film of an automobile.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. Note that the present invention is not limited to only the examples.

Example 1 Polyester putty was coated on a mild steel mild steel plate at 1000 μm, dried at room temperature (20 ° C.) for 1 hour, and polished with # 120 sandpaper. Next, a lacquer-based primer surfacer was applied thereon by 50 μm, dried at room temperature (20 ° C.) for 1 hour, and polished with # 400 sandpaper to obtain a test material.

The test material is coated with 50 µm of urethane PG First Coat (Kansai Paint Co., Ltd., acrylic urethane paint, white) as the first coat of top coat, dried at 60 ° C for 20 minutes, and then polished with # 600 sandpaper. Was done. Then apply 50 μm (dry film thickness) of urethane PG80 metallic color (manufactured by Kansai Paint Co., Ltd., quick-drying acrylic urethane paint, silver metallic color) on the polished top coat first layer coating film, and leave it at room temperature for 3 minutes. , Retan PG-
80 Quartz Clear Z (Kansai Paint Co., Ltd., quick-drying acrylic urethane paint clear) wet-on-wet
60 micron (dry film thickness) was applied and baked at 60 ° C for 30 minutes to prepare a test coated plate.

Example 2 A test material similar to that used in Example 1 was coated with 50 μm of Retan PG First Coat as a top coat first layer paint, dried at room temperature (20 ° C.) for 3 hours, and then #
Polishing was performed with 600 sandpapers. Then, on the polished top coat first layer coating, Retan PG60 White (Kansai Paint Co., Ltd., acrylic urethane paint enamel, white)
After painting 70 microns (dry film thickness) and leaving it to stand at room temperature for 3 minutes, the ratio of the pigment content of 50% to the ratio A of the pigment content to the resin solid content of the urethane PG-60 white, that is, 0.5A
As shown in the figure, Retan PG White is mixed with Retan PG-60 clear (Kansai Paint Co., Ltd., acrylic urethane paint clear), and the top finish paint is wet-on-wet.
It was coated with 25 microns and dried at 70 ° C. for 30 minutes to prepare a test coated plate.

Example 3 Instead of applying 70 μm of Retan PG60 White on the first layer coating film in Example 2, 50 μm of Retan PG60 White (dry film thickness) was applied and wound at 60 ° C. for 30 minutes. The same operation as in Example 2 was carried out except that the surface was polished with a sandpaper of 1000, and then, 25 μm (dry film thickness) of a urethane PG60 white was sprayed thereon.

Example 4 The same procedure was performed as in Example 1 except that the Rethane PG first coat coating film was polished with # 400 sandpaper.

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

Comparative Example 2 The procedure of Example 1 was repeated, except that a lacquer-based primer surfacer was applied in 50 μm (dry film thickness) in place of the urethane PG first coat.

Comparative Example 3 The procedure of Example 2 was repeated except that the Retan PG first coat was not applied.

A test was performed on the test coated plates obtained in Examples 1 to 4 and Comparative Examples 1 to 3 described above. The test results are shown in Table 1 below.

The tests in Table 1 were performed according to the following methods.

(* 1) Feeling of flesh: The degree of flesh of the coating film is visually evaluated under a fluorescent lamp with an illuminance of 1000 lux.

(* 2) Luster: The glossiness of the coating film is visually evaluated under a fluorescent lamp with an illuminance of 1000 lux. Also, measure the 20 ° specular gloss reflectance (20 ° gloss) with a gloss meter.

(* 3) Skin: The smoothness of the coating film is visually evaluated under a fluorescent lamp with an illuminance of 1000 lux. Also, the PGD-I sharpness gloss meter sold by Japan Color Research Institute
Measure the degree of sharpness of the coating film with V.

In addition, the visual evaluation in (* 1), (* 2), and (* 3) was performed according to the following evaluation criteria.

Claims (4)

(57) [Claims] (1) through a primer surfacer coating film,
Alternatively, in a method of repairing a coating film in which a top coat is applied without intervening, as a top coat coating step, (a) an acrylic urethane paint containing a pigment in an amount of 70 to 170 PHR is applied and dried to form a top coat first layer coating film And (b) a step of polishing the first top coat film of the top coat, (c) a colored top coat paint that has been colored is applied onto the polished first coat film of the top coat to form a second top coat film of the top coat. (D) on the top coat second layer coating film,
A method for repairing a coating film, which comprises a step of applying a finish top coating having a pigment content ratio of 0 to 90% of a resin solid content. 2. The step (c) comprises applying a color-coded colored topcoat paint to the ground topcoat first layer coating film, curing the same, and then polishing the cured coating film. 2. The method for repairing a coating film according to claim 1, wherein the method is a step of applying the colored topcoat paint determined in color. 3. The method for repairing a coating film according to claim 1, wherein the top coat first layer coating film is polished with # 600 or a paper finer than # 600. 4. The method for repairing a coating film according to claim 1, wherein the colored top coating composition for forming the second coating film of the top coating and the finishing top coating composition are both acrylic urethane coating compositions.