JP3300831B2 - How to paint the body - 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 a vehicle body, and more particularly, to a method for coating a vehicle body including a step of performing chipping-resistant coating.

[0002]

2. Description of the Related Art There are many cases where the surface of a vehicle body is damaged or peeled off by so-called chipping, which is caused by pebbles or gravel on a road surface being rolled up and colliding with the vehicle body while the vehicle is running. In particular, such a phenomenon often occurs on the lower side of the side sill near the road surface, the lower portion of the fender, or the front panel. If the surface of the vehicle body is damaged or peeled off by such chipping, and if this scratch reaches deeply into the body of the vehicle body, the exposed base material becomes a core and spot rust occurs or rust occurs. Will spread.

Therefore, usually, in order to increase the thickness of the entire coating film in order to avoid generation of spot rust due to chipping,
The bodywork is electrodeposited, the intermediate coating is applied, and then the topcoat is applied.

[0004] Further, by plating the vehicle body base and applying an electrodeposition coating and a top coating to the plating layer, even if the surface of the vehicle body is damaged or peeled, the body of the vehicle is exposed by the plating layer. That's what you do or how to avoid spreading rust.

[0005]

However, in the above-mentioned method of coating a vehicle body for increasing the thickness of the entire coating film, the paint is baked after the intermediate coating, the top coating is applied, and then the top coating is applied. This requires at least two baking steps such as baking, which not only requires labor and labor but also leads to a significant increase in cost.

[0006] Therefore, there has been proposed a method of reducing the number of baking steps by performing anti-chipping coating and applying a predetermined top coating on the wet surface while the coating is in a wet state. However, while the paint is in a wet state, further coatings are applied, so-called wet
When chipping-resistant coating is performed by on-wet coating, there are the following disadvantages. That is, it is difficult to form a wet-on-wet coating only in combination with an intermediate coating or a top coating of a melamine-alkyd material, which is currently used for chipping-resistant coating. When performing wet-on-wet coating in combination with a metallic coating paint, there is a problem that the desired appearance quality and coating adhesion cannot be ensured. Did not.

[0007] The method of performing electrodeposition coating and topcoating after plating the body of the vehicle also has the following disadvantages. That is, the plated steel sheet deteriorates weldability such as spot welding due to the plating layer formed on the surface. Therefore, even if an attempt is made to overstrike a steel plate by spot welding or the like using such a steel plate, the overstrike cannot be performed in some cases, which is inconvenient.

The present invention was conceived in view of the above circumstances, and provides a method for coating a vehicle body capable of wet-on-wet coating of a metallic coating paint or the like on chipping-resistant paint. The task is to provide.

[0009]

DISCLOSURE OF THE INVENTION In order to solve the above problems, the present invention employs the following technical means.

That is, the method of coating a vehicle body according to the present invention is a method of coating a vehicle body including a step of performing a chipping-resistant coating on a painted surface formed by applying an electrodeposition coating to a body of the vehicle. Is performed by applying a paint containing a polyolefin-based resin to the electrodeposition coated surface, and while the paint containing the polyolefin-based resin is in a wet state, a metallic color paint and a paint are applied to the wet surface .
A top coat is applied in order with the rear paint,
Paint containing olefin resin, above metallic color
The paint and the clear paint are simultaneously baked .

Preferably, the coating material containing the polyolefin resin comprises 1.0 to 1.5% by weight of propylene ethylene rubber, 2.0 to 2.5% by weight of a vinylidene chloride vinylidene copolymer, 1.0 to 1.5% by weight of a styrenated alkyd resin.

In the method for coating a vehicle body according to the present invention, a predetermined paint is applied to the wet surface while the paint for chipping-resistant coating applied to the electrodeposition coated surface is in a wet state. It is possible to omit an intermediate coating step that requires baking before the top coating step such as a three-coat coating. Therefore, the productivity in the painting process of the vehicle body is improved, and the cost can be reduced.

[0013] Further, on the wet surface formed by coating a paint containing a resin of polyolefin, making the like metallic coating paint was traditional difficult to lower the adhesion of the appearance quality and coating Without the need for wet-on-wet painting.

Further, the chipping-resistant coating film formed by the coating material containing the polyolefin-based resin may be formed into a very thin film having a thickness of, for example, 3 to 8 μm. Equivalent or higher chipping resistance can be ensured. In addition, by making the thickness of the chipping-resistant coating film extremely thin as described above, the appearance quality of the vehicle body after the coating does not deteriorate.

[0015] Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a flowchart showing a vehicle body painting process in which the vehicle body painting method according to the present invention is employed.
FIG. 4 is a cross-sectional view illustrating a state of lamination of coating films formed by this coating step.

As shown in FIG. 1, the coating process of the vehicle body in the present embodiment includes an electrodeposition coating process, a chipping-resistant coating process, a topcoating process, and a baking process.

First, pretreatment such as degreasing and chemical conversion of the surface of the body 1 made of steel sheet is performed.

Next, an electrodeposition coating is performed on the pretreated body 1 to form an electrodeposition coating layer 2 on the body 1.

Subsequently, a chipping-resistant coating layer 3 is formed on the electrodeposition coating layer 2 by performing a chipping-resistant coating using a predetermined coating apparatus. At this time, a paint containing at least a polyolefin-based resin, for example, propylene ethylene rubber, a vinylidene chloride vinylidene copolymer, and a styrenated alkyd resin is used.
In addition, the film thickness of the chipping-resistant coating film by the above-described chipping-resistant coating is set to a thickness of 3 to 8 μm.

On a wet coating film formed by applying a coating material containing a polyolefin-based resin, a coating material for metallic coating, which has been conventionally difficult, is reduced in appearance quality and adhesion of the coating film. Wet-on-wet painting can be performed without the need.

Then, while the above-mentioned chipping-resistant coating film is in a wet state, a top coat is applied and the chipping-resistant coating layer 3 is formed.
An overcoat layer 4 is formed thereon. In this step, a metallic color paint (base paint) containing a metal pigment such as aluminum powder is applied to form a base paint layer 4a, and a clear paint containing no pigment is produced without baking the base paint. Further paint and clear paint layer 4
forming b.

In the vehicle body thus subjected to the electrodeposition coating, the chipping-resistant coating and the topcoating, the chipping-resistant coating, the base coating and the clear coating are simultaneously baked at 140 ° C., for example.

[0025]

Here, in order to better understand the significance of the present invention, the performance of the coating film formed by the vehicle body coating method according to the present invention is evaluated by the following Examples and Comparative Examples.

[0027]

Example 1 In Example 1, steel plate pieces (iron) were coated using DPX-5A manufactured by Kansai Paint Co., Ltd. having the composition shown in Table 1 below as a coating for chipping-resistant coating. First,
Pretreatment was performed as described above, and then electrodeposition coating was performed to obtain a predetermined film pressure. Subsequently, anti-chipping coating is performed so that the film thickness becomes 5 μm. While the anti-chipping coating thus formed is in a wet state, specifically, for one minute after the anti-chipping coating is completed. After the lapse of time, a metallic color paint containing aluminum powder was applied, and a clear paint containing no pigment was applied without baking the metallic color paint. Subsequently, baking of a chipping-resistant paint, a metallic color paint, and a clear paint was performed at 140 ° C. for 18 minutes.

[0028]

[Table 1]

[0029]

Comparative Example 1 In Comparative Example 1, a steel sheet piece was coated using a coating for chipping-resistant coating having a composition shown in Table 2 below. The respective coating steps were the same as in Example 1, and the thickness of the coating film formed by the chipping-resistant coating was:
75 μm.

[0030]

[Table 2]

With respect to the steel sheet pieces obtained by the coating method according to Example 1 and Comparative Example 1 described above, tests were conducted on the adhesion, appearance quality, and chip resistance, and the results obtained by this test are shown in Table 3. Shown in

[0032]

[Table 3]

In Table 3, ３ indicates good, and Δ indicates good.
Is normal or lower, and x means defective.

The steel sheet obtained by the coating method according to Example 1 has good adhesion to the acrylic melamine-based metallic paint and good chip resistance by using a vinylidene chloride copolymer. More specifically, it has the same or higher chip resistance than a three-coat coating system in which intermediate coating and top coating are performed after electrodeposition coating. The reason why the steel sheet piece obtained by the coating method according to Example 1 has good chip resistance even though it is an extremely thin film is that the coating film obtained by the conventional chip resistance coating has a film thickness effect on chipping. (It absorbs chipping in the vertical direction), but in chip-resistant coatings using chip-resistant paints containing polyolefin resin, it responds to chipping by elongation of the coating (absorption in the horizontal direction) Because they do. In addition, the appearance quality of the steel sheet obtained by the coating method according to Example 1 is superior to the steel sheet obtained by the method according to Comparative Example 1. It is not inferior to the ordinary two-coat paint system for painting, or is more than it.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a vehicle body painting process in which a vehicle body painting method according to the present invention is adopted.

FIG. 2 is a cross-sectional view illustrating a state of lamination of coating films formed by a method of coating a vehicle body according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel plate (body base) 2 Electrodeposition layer 3 Anti-chipping coating layer 4 Top coating layer 4a Base coating layer 4b Clear coating layer

Continuation of the front page (56) References JP-A-6-17294 (JP, A) JP-A-61-114779 (JP, A) JP-A-9-168765 (JP, A) JP-A-6-65791 (JP, A) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B05D 1/00-7/26

Claims (2)

(57) [Claims] 1. A coating method for a vehicle body, comprising a step of performing a chipping-resistant coating on a painted surface formed by applying an electrodeposition coating to a body of a vehicle body, wherein the chipping-resistant coating is a polyolefin-based coating on the electrodeposition-coated surface. It is performed by applying paint containing resin of
While the paint containing the polyolefin resin is in a wet state, a metallic color paint and a clear paint are applied to the wet surface.
And a top coat, and then apply
Paint containing vinyl resin, the above metallic color paint and
And baking the clear paint simultaneously . 2. The coating material containing the polyolefin resin comprises 1.0 to 1.5% by weight of propylene ethylene rubber, 2.0 to 2.5% by weight of vinylidene chloride copolymer, and 1% by weight. The vehicle body coating method according to claim 1, further comprising at least 0.0 to 1.5% by weight of a styrenated alkyd resin.