JPS63232879A - Method for coating vehicle body - Google Patents

Abstract

PURPOSE:To facilitate the color matching by fixing a plastic part applied with a primer coating and two intermediate coatings in another line to the main vehicle body applied with an electrodeposition coating and an intermediate coating, and then carrying out finish coating in the same line. CONSTITUTION:When the main vehicle body 5 made of a steel sheet and plastic parts 1-4 to be integrated into the main body 5 are coated in the same color, the plastic parts 1-4 previously applied with a primer coating in another line and then applied with two intermediate coatings by a paint capable of being used for both resin and steel sheet are fixed to the main body 5 applied with an electrodeposition coating and an intermediate coating by an intermediate coat for steel sheet, and a finish coating by a top coat capable of being used for resin and steel sheet is carried out in the same line. As a result, the color matching of the coating between the main vehicle body and the plastic part is coating between the main vehicle body and the plastic part is coating between the main vehicle body and the plastic part is facilitated. In addition, a finish coated film is formed on both the main vehicle body and the plastic part with good adhesion, and thermal deformation is not caused when the plastic part is coated and baked.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for painting a vehicle body.

More specifically, the present invention relates to a method for painting a vehicle body having resin parts.

(Conventional technology) Conventionally, steel plates have been used as outer panels for automobiles, but there have been demands for a more streamlined car body to improve the appearance and improve fuel efficiency, as well as to reduce air resistance by improving the shape of the car body. As a result, resin-based materials such as filler-mixed resins and polymer alloys, represented by FRP (fiber-reinforced plastics), have recently come to be used more and more as outer panels for automobiles.For example, as shown in Figure 1, , parts such as the bumper or bumper 7 Asia 1, fender 2, door 3, and side sill molding 4 have been converted to resin-based materials (Japanese Patent Laid-Open No. 194-074-1974).

Conventionally, the method of painting a car body using such resin parts is to paint the resin parts and the steel plate body body separately, and then apply the resin parts to the car body body, as shown in Figure 3a. As shown in Figure 3b, after applying electrodeposition coating to the steel plate body and primer coating to the resin parts, the resin parts are assembled to the car body, and then the general Car body painting with steel plate paint (
A method was used in which the intermediate coat and top coat were applied on the same line.

(Problems to be Solved by the Invention) However, in the conventional painting method shown in Figure 3a, the resin parts and the steel plate body are painted separately, so the paint and baking conditions are different. Because of this, it becomes difficult to match the paint color between the car body and the resin parts, especially in the case of metallic paint, and there are also problems such as differences in paint quality and an increase in painting costs. was there. In addition, in the conventional painting method shown in Fig. 3b, the baking temperature is usually 130 to 15°C because common steel plate paints are used for the intermediate and top coats.
Because the temperature is as high as 0°C, there is a risk that resin parts may be deformed during baking, and especially for resin parts that contain fillers, the painted surface may become rough due to the difference in thermal expansion coefficient between the resin matrix and filler during baking. Moreover, there was a problem in that the adhesion between the primer paint for resin parts and the paint for steel plates was poor, resulting in low coating film strength. As described above, the conventional vehicle body painting method shown in FIGS. 3a and 3b has not been able to provide a satisfactory coating on both the steel vehicle body body and the resin parts.

(Means for Solving the Problems) The present invention was made by focusing on such conventional problems, and after applying primer coating in advance on a separate line, resin
Resin parts that have been coated twice with intermediate coating paint for steel plates are attached to the car body that has been electro-deposited and intermediate coated with intermediate coating paint for steel plates, and then top coated with a top coating paint that can be used for resin and steel plates on the same line. By doing so, we attempt to solve the above problems.

(Function) According to the car body painting method of the present invention, since the resin parts and the steel plate car body body are painted at the same time under the same conditions and using the same top coat, the color tone between them is different. Only resin parts where no difference occurs and whose surfaces are prone to roughness due to the difference in coefficient of thermal expansion between the resin matrix and filler are coated with four coats: a primer coat, two intermediate coats, and a top coat. Since the steel plate car body body is not required to be coated with three coats of electrodeposition, intermediate coat and top coat, the exterior finish has sufficient properties and is economical. In general, as a paint used for intermediate coating and top coating on resin parts,
In order to apply a paint that can be used for both resin and steel plates, there is good adhesion between the primer and intermediate coat paint on resin parts, and between the intermediate coat paint and top coat paint, and therefore the adhesion of the finished paint film on resin parts is good. On the other hand, the adhesion between the intermediate coating paint for steel plates and the top coating paint for both resin and steel plates used in the steel plate car body body is good, and the adhesion of the finished coating film is good. Furthermore, since the baking temperature of the paint for both resin and steel plates is relatively low, thermal deformation of resin parts does not occur during baking.

(Example) Hereinafter, the present invention will be explained in more detail based on the drawings. Second
The figures are drawings showing the steps of the car body painting method of the present invention. In the vehicle body painting method of the present invention, exterior parts such as a bumper or bumper fencing 71, a fender 2, a door 3, and a side sill molding 4 as shown in FIG. This is suitably used when it is desired to paint these resin parts and the steel plate vehicle body 5 in the same color for an automobile. As shown in Fig. 2, in the car body painting method of the present invention, the steel plate car body is first subjected to pretreatment processes such as degreasing, chemical conversion treatment, and water washing, as in the case of general car body painting, and then subjected to electrolysis as an undercoating process. A pre-coated paint is applied, and then an intermediate coat is applied using an intermediate paint for steel plates. On the other hand, after resin parts are molded into a predetermined shape, they go through pre-treatment processes such as degreasing and cleaning on a line different from the car body itself, and are then painted with a primer.
Next, an intermediate coating is applied using an intermediate coating paint that can be used for both resin and steel plates, and then an intermediate coating is applied again using an intermediate coating paint that can be used for both resin and steel plates. The resin parts that have been given two intermediate coatings using a common intermediate coating for resin and steel plates are then attached to a steel plate vehicle body that has been given an intermediate coating for steel plates. Next, apply resin to the resin parts and the car body on the same line.
The car body painting is completed by applying a top coat using a common paint for steel plates, and the car body is then transported to the assembly process.

In the car body painting method of the present invention, it is also possible to apply the primer used for resin parts to the car body body after electrodeposition coating, as shown in FIG. 2, and then apply an intermediate coat. At this time, the primer used acts as a chipping primer on the vehicle body, and on the other hand, has the effect of ensuring the adhesion of the paint film on the resin parts and mitigating the impact force on the resin parts.

The primer used in the car body painting method of the present invention is preferably one that does not require a baking process and can be applied as a so-called wet-on-wet intermediate coat.
For example, Soflex 6100, an olefin resin varnish.
UN-'3 (manufactured by Kansai Paint Co., Ltd.), Prograss '1
100UN-102 (manufactured by NOF Corporation) and the like are preferably used.

In addition, both intermediate paints for resins and steel plates and top coats for resins and steel plates should be used at relatively low temperatures, preferably at 70%
It is desirable that it can be baked at a temperature of ~90'C in a short time, preferably about 10 to 60 minutes, and it must have good adhesion to both resin and steel plates. Therefore, it is necessary to have flexibility that can follow the expansion and contraction of resin parts over a particularly wide temperature range.

Specifically, as intermediate coating paints for resin and steel plates, for example, polyurethane-based KPX30-II (manufactured by Kansai Paint Co., Ltd.) and Proglass 4600 (manufactured by Nippon Oil & Fats Co., Ltd.) are also used as top coat paints for resin and steel plates. For example, polyurethane Unicoat X-100 (Kansai Paint Co., Ltd.)
(manufactured by Nippon Oil & Fats Co., Ltd.), Progras 8600 (manufactured by Nippon Oil & Fats Co., Ltd.), and the like are preferably used.

Hereinafter, the present invention will be roughly and concretely explained with reference to Examples.

Fiber reinforced nylon (mineral nylon CM6011RM
12, manufactured by Toshiku Co., Ltd.) and urethane R-RIM (filler RtJ901P, manufactured by Asahi Glass Co., Ltd./urethane = I-
A filler-containing resin specimen using 16OL (manufactured by Nippon Polyurethane Co., Ltd.) was first coated with a primer and two intermediate coats with a common intermediate coat paint for resin and steel plates.
5 After applying electrodeposition coating, chipping primer coating, and intermediate coating with intermediate coating paint for steel plates to the steel plate test pieces, both test pieces were top coated simultaneously on the same line with top coat paint for both resin and steel plates. . The paints and baking conditions used are as shown in Table 1. Regarding the obtained test pieces, color matching, appearance finish, chipping resistance, and cost were examined. The results are shown in Table 2.

Comparative Example 1 The resin test piece was coated with an intermediate coat once, and the steel plate test piece was not coated with a chipping primer.
Roughly speaking, painting was carried out in the same manner as in Example 1, except that the paint used for the intermediate coating was a common intermediate coating for resin and steel plates. The paints and baking conditions used are shown in Table 1.

Regarding the obtained test pieces, color matching, appearance finish, chipping resistance, and cost were examined. The results are shown in Table 2.

Comparative Example 2 A steel plate test piece was coated in the same manner as in Example 1, except that after the intermediate coating was applied with the intermediate coating for steel plates, an intermediate coating was applied using the intermediate coating for resin and steel plates. The paints and baking conditions used are shown in Table 1.

Regarding the obtained test pieces, color matching, appearance finish, chipping resistance, and cost were examined. The results are shown in Table 2.

Comparative Example 3 A filler-containing resin test piece made of the same material as in Example 1 was subjected to primer coating and top coating using the resin paint shown in Table 1 under the baking conditions shown in Table 1. -5 For steel plate test pieces, electrodeposition coating, chipping primer coating, intermediate coating, and top coating are applied using the steel plate paint shown in Table 1 on a separate line from the resin test pieces. The baking was carried out under the baking conditions shown below. The color consistency, appearance finish, and cost of the obtained test pieces were examined. The results are shown in Table 2.

Comparative Example 4 A filler-containing resin test piece made of the same material as in Example 1 was first coated with primer, and a -5 steel plate test piece was coated with electrodeposition and chipping primer. An intermediate coat and a top coat of paint for steel plates were applied simultaneously on the same line. The paints and baking conditions used are as shown in Table 1. The color consistency, appearance finish, and cost of the obtained test pieces were examined. The results are shown in Table 2.

Note that color matching, appearance finish, and cost comparison were measured as shown below.

The color difference between the standard plate and the test piece was determined by the L″a′ b″ system in accordance with Nani-Ni-Kidan JIS Z 8730-80 (color difference display method).

Visual inspection The painted surface of the 1st Tsujigami Prison Test piece was visually compared with a standard board under a fluorescent light or diffused daylight to check for flow on the painted surface and the presence or absence of orange peel. The judgment was based on the following.

Q...Good, △...Standard, X...Bad I CM
(Image C1arit Meter)ICM
, the reflected light from the sample piece is transmitted through an optical comb with a width of 0.5, which is set at an angle of 60 degrees with the incident light, and the image clarity is determined from the maximum value M of the transmitted light in the bright part of the optical comb and the minimum value in the dark part. The C (%) value was determined.

A specified shot material was sprayed onto the test piece using a gravelometer compliant with SAE J600, and the peeling status of the coated surface was examined. The evaluation was graded as follows based on comparison with standard plates.

O: Good, Δ: Standard, X: Poor Varnish The cost required for five-stop painting was calculated and the prices per unit area were compared.

[Effects of the Invention] As described above, the present invention provides an automobile body painting method in which a steel body body and resin parts assembled to the body body are painted in the same color. After that, the resin parts were coated twice with an intermediate coating paint for resin and steel plates, and then attached to the car body, which had been electro-deposited and intermediate coated with an intermediate coating paint for steel plates, and then coated with a top coat paint for resin and steel plates. Since the top coat is applied on the same line, the color matching between the car body and resin parts is better than when the car body and resin parts are painted separately. It is extremely easy to use, and for resin parts whose surfaces are prone to roughness,
Because it is coated, the exterior finish is good.3
The exterior finish matches well with the coated steel vehicle body, and the 4 coat is economical as it can only be applied to resin parts.
Intermediate and top coat paints for steel plates will be applied to the steel body, while intermediate coats for steel plates and top coats for resin and steel plates will be applied to both the body and resin parts. It is formed with good adhesion and there is no thermal deformation during painting baking of resin parts.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing each exterior part of an automobile, FIG. 2 is a process diagram of the car body painting method of the present invention, and FIG.
Figures a-b are process diagrams of a conventional car body painting method. Patent applicant Nissan Motor Co., Ltd. Nissan Shatai Co., Ltd. Figure 1

Claims (1)

[Claims] In an automobile body painting method in which a steel body body and resin parts assembled to the body body are painted in the same color, a primer coating is applied in advance on a separate line, and then an intermediate coating is applied twice with an intermediate coating paint for resin and steel plates. A car body painting method characterized by attaching resin parts to a car body that has been electro-deposited and coated with an intermediate coat paint for steel plates, and then top coated with a top coat paint for both resin and steel plates on the same line. .