JP2510188B2 - Body painting method - Google Patents

Description

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

(Prior Art) Conventionally, a steel sheet has been used as an outer panel for an automobile, but there is a demand for reducing the air resistance by improving the appearance of the vehicle body and reducing the weight of the vehicle body to improve fuel efficiency. As a result, resin-based materials such as filler-mixed resins represented by FRP (Fiber Reinforced Plastics) and polymer alloys have recently come to be used as outer panels for automobiles. For example, as shown in FIG. , Bumper or bumper fascia 1, fender 2, door 3
Parts such as the side sill molding 4 and the like have been converted to resin-based materials (JP-A-57-194,074).

By the way, as a method of painting a vehicle body using such a resin part, conventionally, as shown in FIG. 3a, the resin part and the steel plate body body are separately coated and then the resin body part is attached to the body part. Assembling method, and as shown in Fig. 3b, after applying the electrodeposition coating to the steel body of the steel plate and the primer coating to the resin parts, assemble the resin parts to the body, The method was to apply the vehicle body paint (intermediate coat, top coat) on the same line.

(Problems to be solved by the invention) However, in the conventional coating method as shown in FIG. 3a, since the resin component and the steel plate body are separately coated, the coating material and baking conditions are different. Therefore, it is difficult to match the color of the painting of the vehicle body and the resin parts, especially in the case of metallic color painting, there is a difference in the coating quality, and the coating cost rises. there were. Further, in the conventional coating method as shown in FIG. 3b, since a general steel sheet paint is used for the intermediate coating and the top coating, the baking temperature is usually as high as 130 to 150 ° C. Parts may be deformed, and especially for resin parts containing filler, the painted surface becomes rough due to the difference in the coefficient of thermal expansion between the resin matrix and the filler during baking. However, there is a problem that the adhesion between the steel sheet and the paint for steel sheets is poor and the coating film strength is low. Thus, according to the conventional body painting method shown in FIGS. 3a and 3b,
It was not possible to give a satisfactory coating film to both the steel body body and the resin parts.

(Means for Solving Problems) The present invention has been made by paying attention to such problems in the related art. After the primer coating is applied in advance on another line, the intermediate coating with the resin / steel plate intermediate coating paint is applied. The above resin parts are attached to the body of the vehicle body that has been electrodeposited and coated with an intermediate coating for steel plates, and then overcoated with a resin / steel plate overcoat on the same line. Is to solve.

(Operation) However, according to the vehicle body painting method of the present invention, since the resin component and the steel plate vehicle body are simultaneously coated with the same topcoat paint under the same conditions, the color tone between them is reduced. There is no difference, and only resin parts whose surface is liable to be rough due to the difference in the coefficient of thermal expansion between the resin matrix and the filler are given 4 coats of primer coating, 2 intermediate coatings and top coating. In order to apply the three coats of electrodeposition coating, intermediate coating and top coating to the body of a steel plate body which does not require the above, the appearance finish is sufficiently consistent and economical. Further, as a paint used for intermediate coating and top coating on resin parts, since a common coating for resin and steel plate is applied, adhesion between the primer and the intermediate coating, or the intermediate coating and top coating on the resin parts is good, Therefore, the adhesion of the finished coating film on the resin parts will be good, while the adhesion between the steel sheet intermediate coating paint and the resin / steel sheet topcoating paint that is also used on the body of the steel sheet will be good, and the adhesion of the finished coating film will be good. The quality is good. Further, since the baking temperature of the coating material for both resin and steel plate is relatively low, thermal deformation of the resin parts does not occur during baking.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 2 is a drawing showing the steps of the vehicle body painting method of the present invention.
The vehicle body painting method of the present invention is applied to, for example, a bumper or bumper fascia 1, a fender 2, as shown in FIG.
Suitable for the case where the exterior parts such as the door 3 and the side seal molding 4 are made of a resin-based material such as a filler-containing resin and the resin parts and the steel plate vehicle main body 5 are painted in the same color. Is used for. As shown in FIG. 2, in the vehicle body painting method of the present invention, the steel plate body is first subjected to pretreatment steps such as degreasing, chemical conversion treatment, and water washing as in the case of general vehicle body painting, and then the undercoating step is carried out. The coating is applied, and the intermediate coating for steel plates is applied. On the other hand, resin parts are molded into a specified shape, then undergo a pre-treatment process such as degreasing and cleaning on a line different from the body of the car body, then primer coating, and then intermediate coating with resin / steel plate intermediate coating paint. Then, again, the intermediate coating with the resin / steel common intermediate coating is applied again. The resin-made parts that have been subjected to the two-time intermediate coating with the resin-steel intermediate coating paint are then mounted on the steel plate body body that has been subjected to the intermediate coating for steel plates. Subsequently, the resin-made parts and the body of the vehicle body are coated on the same line with the resin / steel sheet common topcoating, thereby completing the bodywork painting and carrying the vehicle body to the assembly process.

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

The primer used in the car body coating method of the present invention does not require a baking step,
It is desirable to be able to apply the middle coat on wet, for example, olefin resin varnish type Soflex 6100
UN-3 (Kansai Paint Co., Ltd.), Pro Glass 1100UN-
102 (manufactured by Nippon Oil & Fats Co., Ltd.) and the like are preferably used. Further, both the resin / steel plate intermediate coating and the resin / steel common top coating are both at a relatively low temperature, preferably 70 to 90
It is desirable that it can be baked at a temperature of ℃ for a short time, preferably for a treatment time of about 10 to 60 minutes, and it is necessary to have good adhesiveness to both the resin system and the steel plate system, In particular, it is necessary to have the flexibility to follow the expansion and contraction of the resin part in a wide temperature range. Specifically, as the intermediate coating paint for both resin and steel plate, for example, polyurethane-based KPX30-II (manufactured by Kansai Paint Co., Ltd.), Prograss 4600 (manufactured by NOF CORPORATION, etc.), etc. For example, polyurethane-based Unicoat X-100 (manufactured by Kansai Paint Co., Ltd.), Prograss 8600
(Nippon Yushi Co., Ltd.) and the like are preferably used.

Hereinafter, the present invention will be described more specifically by way of examples.

Fiber reinforced nylon (mineral nylon CM6011RM12, manufactured by Toray Industries, Inc.) and urethane R-RIM (Fila = RU901
P, Asahi Glass Co., Ltd./Urethane = I-160L, made by Nippon Polyurethane Co., Ltd. First, primer coating and two intermediate coatings with resin / steel plate intermediate coating on resin-filled resin test pieces. On the other hand, after applying the electrodeposition coating, the chipping primer coating and the intermediate coating with the steel sheet intermediate coating to the steel sheet test pieces, both test pieces are simultaneously overcoated with the resin and steel sheet common top coating on the same line. Was carried out. The paints used and baking conditions are as follows:
As shown in the table. With respect to the obtained test pieces, color matching, appearance finish, chipping resistance and cost were examined. The results are shown in Table 2.

Comparative Example 1 Example except that the intermediate coating of the resin test piece was performed once, the chipping primer coating was not applied to the steel plate test piece, and the coating used for the intermediate coating was the resin / steel plate intermediate coating paint. Painting was performed in the same manner as in 1. The paints used and the baking conditions are as shown in Table 1. Color consistency with respect to the obtained test piece,
The 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 with the intermediate coating for steel plates, the intermediate coating with the resin / intermediate coating for steel plates was applied. The paints used and the baking conditions are as shown in Table 1. Regarding the obtained test piece, color matching, appearance finish,
The chipping resistance and cost were examined. The results are shown in Table 2.

Comparative Example 3 Using a resin coating material shown in Table 1 on a filler-containing resin test piece made of the same material as in Example 1, primer coating and topcoat coating were performed under the baking conditions shown in Table 1. On the other hand, for steel plate test pieces, in a line separate from the resin test piece, using the steel plate paint shown in Table 1, electrodeposition coating, chipping primer coating, intermediate coating and top coating are shown in Table 1. It was carried out under the baking conditions shown. The obtained test pieces were examined for color matching, appearance finish and cost. 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 subjected to primer coating, while a steel plate test piece was subjected to electrodeposition coating and chipping primer coating, and then both test pieces were subjected. On the same line, the intermediate coating and the top coating were simultaneously performed with the steel sheet paint. The coating materials used and the baking conditions are as shown in Table 1. The obtained test pieces were examined for color matching, appearance finish and cost. The results are shown in Table 2.

The color matching, appearance finish, and cost comparison were measured as follows.

Color Consistency According to JIS Z 8730-80 (color difference display method), the color difference between the standard plate and the test piece was determined by the L ^* a ^* b ^* system.

Appearance Finishability Visually, the coated surface of the test piece was visually compared with a standard plate under fluorescent light or diffused daylight, and the flow of the coated surface and the presence or absence of orange peel were examined. The determination was based on the following.

○: good, △: standard, ×: bad ICM (Image Clarity Meter) In ICM, the reflected light of the sample piece is transmitted through the 0.5 mm wide optical comb installed at an angle of 60 ° with the incident light to The image clarity C (%) value was obtained from the maximum value M of transmitted light in the bright part and the minimum value in the dark part.

Chipping resistance A specified shot material was sprayed onto the test piece using a gravimeter conforming to SAE J600, and the peeling condition of the coated surface was examined. The judgment was classified into the following grades by comparison with the standard plate.

○: Good, △: Standard, ×: Bad Cost comparison We calculated the cost of painting and compared the price per unit area.

[Advantages of the Invention] As described above, according to the present invention, in a vehicle body painting method for an automobile, in which a steel plate body body and a resin component assembled to the body body are painted in the same color, a primer coating is previously applied in a separate line. After that, the resin parts that have been subjected to the intermediate coating with the resin / steel sheet intermediate coating paint twice are attached to the body of the vehicle body that has been subjected to the electrodeposition coating and the steel sheet intermediate coating coating, and then the resin / steel sheet common coating Since the top coating is performed on the same line, the color matching of the body and resin parts is different from the case where the body and resin parts are painted separately. It is extremely easy, and since the resin parts whose surface is rough are coated with 4 coats, they have a good appearance finish, which is in good agreement with the appearance finish of the steel plate vehicle body with 3 coats. In addition, the 4 coat is economical because it is applied only to resin parts. Furthermore, resin and steel plate common intermediate coating and top coat paint are applied to resin parts while steel plate body bodies are used for steel plates. Since the intermediate coating and the resin / steel plate top coating will be applied, the finished coating will be formed on both the vehicle body and the resin parts with good adhesion, and there will be no thermal deformation during baking of the resin parts. .

[Brief description of drawings]

FIG. 1 is a perspective view showing each exterior part of an automobile, FIG. 2 is a process diagram of a vehicle body painting method of the present invention, and FIG.
FIGS. 3A to 3B are process diagrams of a conventional vehicle body painting method.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Shingu 2 Takaracho, Kanagawa-ku, Yokohama-shi Nissan Motor Co., Ltd. (72) Inventor Takashi Toyama 2 Takaracho, Kanagawa-ku, Yokohama-shi Nissan Motor Co., Ltd. (72) Inventor Akira Yamashita 10-1 Amanuma, Hiratsuka-shi, Nissan Shatai Co., Ltd. (72) Inventor Watano Hatano 10-1 Amanuma, Hiratsuka-shi, Nissan Shatai Co., Ltd.

Claims (1)

(57) [Claims] 1. A vehicle body painting method for an automobile, wherein a steel body made of steel and a resin part assembled to the body are painted in the same color. In this method, a primer coating is applied in advance on a separate line, and then an intermediate coating with a resin / steel intermediate coating paint is applied. The resin parts that have been painted twice are attached to the body of the car body that has been electrodeposited and the intermediate coating of the steel sheet has been applied.
A body painting method characterized in that the top coating is applied on the same line as the top coating for both steel plates.