JPH091061A - Method for repairing clear paint film - Google Patents

Abstract

PURPOSE: To make a subsequent polishing process simple by a method in which in advance of the application of a repairing paint, the surface of a repair part is wetted with one or more kinds of organic solvents selected from specified ester-type and ether-type organic solvents. CONSTITUTION: In a repairing method in which the repair part of a crosslinked clear paint film is sanded and coated with a repairing paint, in advance of the application of the repairing paint, the surface of the repair part is wetted with one or more kinds of organic solvents selected from ester type organic solvents with a boiling point of 200-250 deg.C and ether type organic solvents with a boiling point of 200 250 deg.C. In this way, the wettability of the repairing paint improves so that the applied paint can spread thinly. After the application, the paint film is crosslinked in conditions according to the composition of the paint. After curing, the difference in the evenness from an unrepaired part is eliminated as necessity requires, or the repaired part is polished for glossing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a clear coating film repairing method,
In particular, the present invention relates to a new coating film repairing method in which a repairing paint (so-called touch-up paint) has excellent wettability and a polishing process is simplified.

[0002]

2. Description of the Related Art The coating of outer panels of automobiles is usually composed of steps such as undercoating (usually cationic electrodeposition coating), intermediate coating, metallic coating and clear coating. Then, in this step, minute coating film defects such as dents, spots, and cissing may occur on the clear coating film. Since this defect causes a significant deterioration in the appearance of the coating film, repair coating is required to remove that portion.

In the conventional repairing method, the defective portion of the clear coating film and its peripheral portion are sanded to remove dents, spots, cissing, etc., and the polishing portion is painted with a repairing paint or the like. After being cured, it is carried out by polishing so that the height of the coating film surface of the repaired portion becomes the same height as the other coating film surfaces in the periphery.

However, according to such a method, since the repair paint is not sufficiently wet (wettability) with respect to the repair part, the repair paint is applied in a thick wall as if it were raised in the repair part. It took a great deal of time and labor to make the height of the coating film the same as that of the peripheral coating film. Furthermore, in recent years, clear coating films have been strongly crosslinked and cured in order to improve acid resistance, scratch resistance, etc., and their coating surfaces have become chemically inactive. There is also a defect that the adhesiveness of is insufficient.

[0005]

Means for Solving the Problems The present inventor has conducted diligent research in order to solve the above-mentioned problems in repairing a cross-linked and cured clear coating film, and as a result, as a result, prior to coating of a repair coating, the surface of the repaired portion was coated. Is wetted beforehand with one or more organic solvents selected from ester organic solvents having a boiling point of 200 to 250 ° C. and ether organic solvents having a boiling point of 200 to 250 ° C. It has been found that the polishing property is improved and the repaired portion after coating with the coating material is easily polished, so that the polishing process can be simplified and the adhesion to the repaired coating film is improved, and the present invention has been completed. It was

That is, the present invention provides a method of sanding a repaired portion of a crosslinked and cured clear coating film, and then applying a repairing paint to the portion to repair the repaired portion, prior to coating the repairing material. Boiling point is 20
Ester-based organic solvent of 0 to 250 ° C and boiling point of 200
The present invention relates to a clear coating film repairing method, which comprises moistening with one or more organic solvents selected from ether organic solvents at 250 ° C.

In the present invention, as a cross-linked and cured clear coating film, for example, a clear coating formed on a multi-layer coating surface in which an electrodeposition coating material, an intermediate coating material and a metallic (also solid color) coating material are successively applied to an automobile outer panel or the like. Examples of the coating film include a coating film, and a coating film formed by a method other than these is also included. The clear coating film is preferably cured by three-dimensional crosslinking reaction.

The crosslinked and cured clear coating film is coated with a clear coating composition containing a base resin and a crosslinking agent as main components, and if necessary, an organic solvent, a curing catalyst, an ultraviolet absorber and the like, and then applied at room temperature or under heating. Then, it can be formed by crosslinking and curing. Coloring pigments and metallic pigments can also be added to the extent that they do not impair the transparency of the coating film. The base resin is one or more functional groups selected from hydroxyl group, epoxy group, isocyanate group, blocked isocyanate group, alkoxysilane group, silanol group, carboxyl group, amino group, polymerizable unsaturated group-containing resin, and the like. Examples thereof include acrylic resins, alkyd resins, epoxy resins, urethane resins, and silicon-containing resins. As a cross-linking agent, melamine resin, polyisocyanate compound,
Block polyisocyanate compound, epoxy compound,
1 selected from a compound containing a carboxyl group, an amino compound, a compound containing a hydroxyl group, a compound containing a polymerizable unsaturated group, etc.
Species or two or more can be used. The combination of the base resin and the cross-linking agent can be arbitrarily selected depending on the combination of the functional groups possessed by each.

In the present invention, micro-defects such as spots, craters and dents generated in the cross-linking cured clear coating film formed by the above composition and method (the individual size is usually about 1 to 3 mm in diameter, or less) ) And its peripheral portion are sanded, that is, polished, as a repair portion to remove the defective portion. Sanding can be performed by a known method using a polishing paper, a polishing cloth, a polishing machine, or the like.

In the present invention, after the repaired portion of the clear coating film surface is sanded and before the repair coating material is applied, the coating surface of the sanding portion (repaired portion) has a boiling point of 200-200.
Ester-based organic solvent at 250 ° C. and boiling point of 200 to 2
It is essential to wet with one or more organic solvents (hereinafter referred to as wetting solvents) selected from ether organic solvents at 50 ° C.

In the wetting solvent, the ester organic solvent may be any solvent having the above boiling point range and having at least one ester bond in one molecule, for example, γ-valerolactone, benzyl acetate, diethylene glycol monomethyl acetate. Examples thereof include ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, methoxytriglycol acetate, dibutyl oxalate, diethyl maleate, dibutyl maleate, and diethylene glycol monoethyl ether acetate. The ether organic solvent may be a solvent having the above boiling point range and having one or more ether bonds in one molecule, and examples thereof include hexyl ether, 2-ethylhexyl ether, ethylene glycol mono-n-hexyl ether, Ethylene glycol monophenyl ether, ethylene glycol dibutyl ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol mono-n-
Hexyl ether, ethoxy triglycol, tetraethylene glycol dibutyl ether and the like can be mentioned.

Among the above solvents, preferred examples include diethylene glycol monoethyl ether acetate and diethylene glycol monobutyl ether.

As the wetting solvent, one kind or two or more kinds selected from these can be used. Further, the wetting solvent is preferably composed of only it, but it may be used in combination with other organic solvents other than the above composition or boiling range, in which case the wetting solvent based on the total weight. The content is preferably 50% by weight or more, and particularly preferably 65% by weight or more.

The method of moistening the coated surface of the sanding portion (repair portion) with a wetting solvent is not particularly limited. For example, a brush, a brush, or a sprayer is used to apply the wetting solvent to the sanded coated surface. It can be carried out. For example, it can be suitably wetted by wiping with a cloth containing a wetting solvent. The amount of the wetting solvent applied is not particularly limited and is, for example, 5
A range of about 0 to 100 g / m ² is suitable.

In the present invention, after being wet in this manner, the repair paint is applied while the wetting solvent remains (wet) on the coated surface.

As the repair paint, it is preferable to use one selected from those explained in the above clear paint. The coating can be performed by applying the coating material to the sanded coating surface using, for example, a brush, a brush, a sprayer or the like. The amount of the coating material for repair applied can be arbitrarily selected depending on the shape and size of the portion to be repaired, but it is at least the amount removed by polishing based on the solid content.
In the present invention, by moistening the repaired portion with the wetting solvent, the wettability of the repair coating material is improved, and the coated repair coating material spreads thinly on the repaired portion.

After coating, the coating film is crosslinked and cured under the conditions according to the composition used. After curing, if necessary, the unevenness with other non-repair coating film is eliminated, or the repair paint coating portion is polished for glossing. For example, polishing can be performed by polishing, polishing with water, etc. Specifically, it can be preferably carried out by using polishing paper, polishing cloth, steel wool, portable sander, or the like.

[0018]

【The invention's effect】

1. The repair paint has excellent wettability and spreads thinly on the repaired part, simplifying the subsequent polishing process.

2. Even with a clear coating film having improved acid resistance and scratch resistance, the use of a wetting solvent markedly improved the adhesion to the repair coating.

[0020]

EXAMPLES Examples and comparative examples of the present invention will be described.

Examples 1 and 2 A cationic electrodeposition coating (epoxy-amine resin / block polyisocyanate system) and an intermediate coating (polyester resin / melamine resin system) were applied to an outer panel (steel plate) of an automobile and heat-cured. Next, metallic paint (acrylic resin /
Melamine resin system) and the following clear paint by the wet-on-wet method, and both coating films are heated at 140 ° C. for 30 minutes.
Heat cured in minutes.

This clear coating composition was obtained from a monomer composition of a hydroxyl group-containing acrylic resin (40 parts by weight of methyl methacrylate, 44 parts by weight of ethyl acrylate, 15 parts by weight of 2-hydroxyethyl methacrylate and 1 part by weight of methacrylic acid, 70 parts by weight of number average molecular weight 15,000, 30 parts by weight of butyl etherified melamine resin and toluene / xylene (1/1, weight ratio) (viscosity: Ford Cup # 4
/ 20 ° C./15 seconds) as a main component, and its film thickness is 40 to 45 μm based on the cured coating film. Then, the spots, craters, and dents (individual size is usually 1 mm or less in diameter) generated on the surface of the clear coating film and its peripheral portion (diameter of about 30 cm) are polished with # 1500 waterproof paper only for the clear coating layer. The defects were removed (by sanding).

Then, the polishing portion was coated with diethylene glycol monobutyl ether (boiling point: 230 ° C.) (Example 1) or diethylene glycol monoethyl ether acetate (boiling point: 246 ° C.) (Example 2) with a coating amount of 60 g. / M ² evenly and uniformly, while the solvent is wet, the clear coating is 0 to 20 μm so that the central portion of the polished portion has a maximum film thickness and becomes thinner successively. Repair coating was applied at a thickness (as a cured coating film), and the repaired portion was cured by heating at 140 ° C. for 30 minutes by infrared irradiation. Then, polishing was performed with a polishing cloth so that the height of the coated surface of the repair coating portion and the periphery thereof were the same.

Comparative Examples 1, 2, 3 and 4 The wiping solvents in the above examples were ethyl acetate (boiling point 77 ° C.) (Comparative Example 1), xylene (boiling point 140).
C.) (Comparative Example 2) and triethylene glycol (boiling point 287 ° C.) (Comparative Example 3), except that the procedure was the same as in Example.

Comparative Example 4 is an example in which a repair paint was directly applied after polishing without being wet with a solvent.

The results of comparison of the buffing time (minutes), the finished appearance (visual inspection) and the adhesiveness in the above Examples and Comparative Examples are shown in Table 1 below.

[0027]

[Table 1]

The adhesion test in Table 1 above was carried out by making 100 squares having a size of 1 mm × 1 mm on the coated surface with a goggles cutter, sticking an adhesive cellophane tape on the surface, and rapidly peeling it off. Number of paint films remaining on the surface
Is the result of examining.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masataka Muramatsu 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd. (72) Inventor Shigeru Nakamura 1 Mizo-cho, Nishikamo-gun, Aichi Prefectural plain 1 Kansai Paint Co., Ltd. Within

Claims (1)

[Claims] 1. A method for sanding a repaired portion of a cross-linked and cured clear coating film, and then applying a repairing paint to the repaired portion, wherein the surface of the repaired portion is coated prior to applying the repairing coating material. Clear coating film characterized in that it is moistened with one or more organic solvents selected from ester organic solvents having a boiling point of 200 to 250 ° C. and ether organic solvents having a boiling point of 200 to 250 ° C. Repair method.