JP3176810B2 - How to paint a car - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating an automobile body, and more particularly to a method for coating a solid paint.

[0002]

2. Description of the Related Art As shown in FIG. 1, different coatings are applied to an outer panel 2 and an inner panel such as an engine room, a door opening and a room. On the inner plate, the inner plate color using inexpensive paint is applied on the middle coat by wet-on-wet, and the outer plate is also overcoated on the middle coat to ensure the concealment of the top coat. Has been given.

FIG. 2 shows the process. After forming an electrodeposition coating film and baking and drying, apply an intermediate coating to both the outer plate and the inner plate, and apply an inexpensive inner plate color to the inner plate by wet-on-wet on the intermediate coating. After the application, the car body is placed in a furnace, and the intermediate coating film and the inner plate color coating film are baked and dried. Thereafter, a top coat is applied to the outer plate portion, and the vehicle body is put into a furnace again to bake and dry the top coat.

FIG. 3 schematically shows a boundary region between an inner plate portion and an outer plate portion. As shown in FIG. 3, an electrodeposition coating film 8 (generally, a dark gray type) is formed on a steel plate 6, and An intermediate coating film 10 is formed, and an inner plate color film 12 is formed on the intermediate coating film 10 in the inner plate portion. On the other hand, in the outer plate portion 2, the top coat 14 is formed on the middle coat 10.

[0005]

The conventional method of providing an intermediate coating step requires three coating steps and two baking and drying steps after the electrodeposition coating, which requires a large number of steps, and requires equipment and man-hours. Disadvantageous. When the inner plate color is applied on the intermediate coating film 10, dust 12a of the inner plate color may be generated. In the case of a solid top coat, if the coating color is a clear color with no turbidity and a vivid color, the concealability is poor.
If the inner plate color dust 12a adheres to the top surface 0, the dust 12a is seen through the top coat 14, and there is a problem that the appearance quality is deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the number of steps to reduce the cost and to improve the appearance quality by eliminating the influence of dust on the outer plate portion generated when a dedicated inner plate color paint is used. Things.

[0007]

According to the present invention, as shown in FIG. 4, after an electrodeposition coating film is formed on a steel plate, it has the same resin composition as that of the top coating film and has the same resin composition. A top coat base film adjusted to a pigment concentration higher than the pigment concentration is applied to the outer plate and inner plate in common, and only the outer plate is further coated with a top coat top coat on a wet-on-wet basis. Then, the whole is baked and dried.

[0008] The intermediate coating is eliminated, and a top coat base coating is applied to both the outer plate and the inner plate instead. As a result, the number of application steps after electrodeposition coating is reduced to two steps, and baking and drying is also reduced to one step, thereby reducing the number of steps. Also,
Since the top coat base film, which is the lower layer of the top coat film, is common to the inner plate portion and the outer plate portion, there is no influence of dust due to the exclusive inner plate color paint as in the prior art.

FIG. 5 schematically shows a boundary region between the inner plate portion and the outer plate portion.
A top coat base coat 20 is commonly formed on the top, and a top coat top coat 22 is further formed on the outer plate portion 2. The inner plate part 4 is finished with a top coat base coat 20. The overcoat base coating film 20 is set to an L value similar to that of the electrodeposition coating film 8. The L value is the L value of the Hunter's color difference formulas L, a, and b.

An inexpensive pigment can be used as the top coat base paint, and its pigment concentration is adjusted so as to be higher than the pigment concentration of the paint of the top coat 22. If the color of the top coat base coat 20 is the same as that of the top coat top coat 22, or if the combination of the top coat base coat 20 and the top coat top coat 22 produces vivid colors, the top coat base coat 20 As the color 20, a color similar to the color of the top coating film 22 can be used. The top coat base coat 20 and the top coat top coat 22 have the same resin composition and different solvent settings. According to the present invention, it is possible to inexpensively deal with vivid colors. This is because the inner plate part 2 is finished with an inexpensive topcoat base, and its concealing property can be ensured by a two-layer film with the electrodeposition coating film 8.

[0011]

An embodiment will be described with reference to FIGS.
An electrodeposition coating film 8 is formed on a steel plate 6 by an ordinary method. The coating material for the electrodeposition coating film 8 is an epoxy-based cationic electrodeposition coating material containing titanium oxide, carbon black, or the like as a pigment, and has a solid content adjusted to 20% by weight. The paint is applied to a thickness of about 20 μm and baked and dried at 170 ° C. for 20 minutes to form an electrodeposition coating film 8.

An overcoat base coat 20 is applied on the inner plate 4 and the outer plate 2 in common. The coating of the overcoat base coating film 20 uses an alkyd-melamine resin as a main component resin, and disperses it in a special thinner as a solvent with a coloring pigment such as redwood and azo red.
It is a paint adjusted to be 7.5% by weight, and the paint is applied to a thickness of about 15 μm by an air spray gun method.
Apply so that

On the base coat 20, a wet
The top coat 22 is applied on a wet basis. The paint for the top coat 22 is an alkyd-melamine resin which is the same as the resin of the paint for the top coat 20 as a main component resin, and a coloring pigment such as quinacridone red or ad red is used as a solvent. It is a paint that is dispersed in thinner and adjusted to have a solid content concentration of 45.8% by weight, and the paint is applied only to the outer plate portion 2 by an air spray gun method so as to have a coating thickness of about 25 μm. I do.

Thereafter, the top coat base coat 20 and the top coat top coat 22 are simultaneously baked and dried at 140 ° C. for 20 minutes. The coating composition, coating film thickness, coating method and the like of each coating film are not limited to those shown in the examples. As a means for coating the top coat base coat and the top coat top coat, an airless spray method or an electrostatic coating method may be used in addition to the air spray method.

[0015]

According to the present invention, the intermediate coating is eliminated, and the top coating base film is formed in common on the outer plate portion and the inner plate portion instead. Therefore, the coating process after the electrodeposition coating is reduced to two processes. In addition, baking and drying are also reduced to one step, and the number of steps is reduced. In addition, since the top coat base film, which is the lower layer of the top coat film, is common to the inner plate and the outer plate, there is no dust effect due to the special inner plate color paint as in the past, and the outer plate appearance Quality is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an outer plate portion and an inner plate portion on which an automobile body is coated.

FIG. 2 is a flowchart showing a painting process in a conventional method.

FIG. 3 is a schematic sectional view showing a boundary portion between an outer plate portion and an inner plate portion painted by a conventional method.

FIG. 4 is a flowchart showing a coating method of the present invention.

FIG. 5 is a schematic cross-sectional view showing a boundary region between an outer plate portion and an inner plate portion of a coating film formed according to one embodiment.

[Explanation of symbols]

 2 outer plate part 4 inner plate part 6 steel plate 8 electrodeposition coating film 20 top coat base coat 22 top coat top coat

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-175674 (JP, A) JP-A-1-168388 (JP, A) JP-A-1-210082 (JP, A) JP-A-4- 66163 (JP, A) JP-A-4-104867 (JP, A) JP-A-4-330965 (JP, A) JP-A-5-185031 (JP, A) JP-A-7-116596 (JP, A) JP-A-8-71456 (JP, A) JP-A-61-238370 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B05D 1/00-7/26

Claims (1)

(57) [Claims] 1. After forming an electrodeposition coating film on a steel plate of an automobile, a topcoat basecoat having the same resin composition as the coating of the topcoat topcoat and adjusted to a higher pigment concentration than the pigment concentration of the topcoat topcoat. It is characterized in that the film is applied to both the outer plate and the inner plate in common, and only the outer plate is further coated with a top coat wet-on-wet, and then the whole is baked and dried. How to apply solid paint for automobiles.