JPS6071224A - Coating method for resin molded article having deep- drawn portion - Google Patents

Abstract

PURPOSE:To coat a resin molded article having a deep-drawn portion, by spraying a coating material onto the projection of a mold for forming the deep-drawn portion, and by applying the coating material on the surfasce of the molded article after resin is molded monolithically. CONSTITUTION:In the state that a mold composed of a mold 2 in which a projection 5 for forming a deep-drawn portion is formed on a cavity 4 forming side and a mold 3 corresponding to the mold 2 is opened, a coating material is sprayed on the projection of the mold. Then, said mold is closed and a resin is introduced into it to form a molded article 19. Next, the molded article 19 is taken out of the mold and a coating material of synthetic resin is applied on the surface of the molded article. The surface of the molded article is coated in the following process, after the deep-drawn portion is masked with a masking tape 22, a primer is applied thereon, and then, after the masking is removed, a topcoat is applied on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a coating method for uniformly applying paint to the surface of a resin molded article having a recessed part, particularly the recessed part. .

(Prior Art) Recently, weight reduction of car bodies has been adopted as a measure to reduce the fuel consumption of automobiles, and efforts are being made to replace metal parts in various parts of car bodies with synthetic resin molded products as much as possible. Among them, when applied to soft facia S as shown in Figure 7, which shows a cross section of a synthetic resin molded product, this soft facia S is attached to the surface of the car body, and the material is available in many colors. In this case, since the finish color is not the same as the car body, it is customary to paint the surface with paint P to finish it in the same color as the car body. Therefore, if the surface shape of Soft Facial S is smooth, the paint p
It is possible to apply the paint p unevenly (but if the surface to be painted has a hollowed-out area n, it is difficult to apply the paint p evenly to the hollowed-out area n, so the coating film may be defective). There is a problem in that the coating becomes uniform and impairs the appearance as shown in the column of "Conventional method" in Table 7, and in particular, in the case of metallic coating, metal misalignment occurs.

Therefore, after molding a synthetic resin molded product in a mold, the mold was slightly opened to create a small gap between the mold and the molded product, and paint was injected into this gap from the paint port provided in the mold. One method of in-mold coating is known, in which pressure is applied afterwards, but this method eliminates the above-mentioned drawbacks of the conventional method, as the paint does not flow well (a uniform coating film is not formed) if the searched portion n is formed. It's not something you do.

(Object of the Invention) In view of the above-mentioned conventional problems, the present invention is based on the results of various experiments such as "painting of the searched portion of a resin molded product".

It has been found that good results can be obtained by preceding the molding process of the molded product, so the protrusion formed on the cavity forming surface of the other mold while the mold is in an open state. The purpose of this is to spray paint in advance on the area to form a uniform coating on the searched area.

(Structure of the Invention) The structure of the present invention is such that when the molding die is opened, the entire surface of the protruding part for forming the recessed part formed on the cavity forming surface of the mold forming one half of the molding die is Spraying is a process in which a synthetic resin molded product is sprayed, a process in which a mold is clamped and a synthetic resin is introduced into the mold to form a molded product that is integrated with the paint; The method is characterized in that the molded product is removed from the molding die, and a product surface coating step of applying a synthetic resin paint to the surface of the molded product having the above-mentioned search marks is sequentially performed.

(Example) Hereinafter, the configuration of the present invention will be explained in detail from the implementation side.

Fig. 1 shows a molding die 1 that is applied to molding synthetic resin products such as soft fascias, and the molding die has a concave shape 2.
and a mold 3 for the concave mold. Inside the cavity 4 of the concave mold 2 is a search section 1 for a molded product 19, which will be described later.
A protrusion 5 corresponding to 8 is formed, and the core 6 of the mold B
A deep groove portion 7 is formed in the protrusion portion 5 .

The method of the present invention is carried out by applying the above-mentioned molding die 1, and the mold release agent application step 8, the spraying step 9, the injection molding step 10, the cleaning step 11, and the product surface coating step 12 are carried out in this order. It is constructed as the main part.

In the mold release agent application step 8, with the mold 1 open as shown in FIG.
A wax mold release agent 14 is applied to each mold surface of the core 6 using a spray coating device 13.

In step 9 of the spraying process, following the mold release agent application step 8, with the mold 1 open, as shown in FIG. A coating layer 15 made of a two-component urethane paint is applied using a spray coater 16 to form a coating film with a thickness of 70 to 30 μm, and then left to cure for 7 to 5 minutes.

In the injection molding step 10, after the spraying step 9, as shown in FIG. A molded article 19 having a cut-out portion 18 such as a soft fascia is molded integrally with the coating layer 15, and left for 2 to 3 minutes to harden.

In the cleaning step 11, after the injection molding step 101, the molded product 19 is taken out from the molding die 1, and then the weir 20 and other unnecessary parts are removed from the molding step 7 as shown in FIG.
Arrange the product shape of the molded product 19 as shown in the figure, /, /,
The molded article 19 is degreased and cleaned by continuing steam cleaning with /-trichloroethane for 60 to 720 seconds.

The product surface painting step 12 includes an undercoat step 12a and a top coat, ff1l 2b.The undercoat step 12a is performed after the cleaning step 11, as shown in No. 66, by turning the surface 21 of the molded product 19 upward. Then, masking tape 22 is applied to the outer edge of the part to which the coating layer 15 has been applied, and then the surface 21 of the molded product 19 is covered with 2
A paint device 24 sprays a primer 26 using liquid urethane paint.
After coating to form a coating film thickness of 75 to 30μ,
/2θ0C and harden for 20 minutes. The top coating step 12b is followed by the undercoating step 12al, and as shown in FIG. Paint with a spray paint machine 26,
After forming a coating film with a thickness of 20 to θμ, /2θ0C
Heat to harden for 30 minutes.

In the method of the above embodiment, the locating portion 18 of the molded product 19 that is difficult to paint is easily and uniformly coated by spraying step 9, which is performed prior to the injection molding step 10 of the molded product 19. Even if the top coat 25 does not bend into the deep part of the deep scarf part 18 in the surface painting process 12, if the top coat and the coating layer 15 are made the same color, the appearance of the finished product will not be impaired. . Incidentally, when an attempt was made to paint a synthetic resin molded article having a searched portion based on the above-mentioned method of the example, favorable results were obtained as shown in the column of "Method of the present invention" in Table 2.

Note that the cleaning step 11 and the undercoating step 12a of the above embodiment
The application of the masking tape 22 may be omitted depending on the coating specifications, and instead of this example, the top coat 25 may be applied in the spraying step 9, and the product surface painting step 12 may be performed only in the top coating step 12b. can.

(Effects of the Invention) According to the above configuration of the present invention, a resin molded product having a search part is formed with a uniform coating film on the search part during the spraying process, and is formed integrally with the coating film on the search part. After going through the molding process, a uniform coating film is formed on the surface of the molded product having the above-mentioned cut-out parts in the product surface painting process, so it can be finished with a uniform painted appearance, and is especially excellent in the case of metallic paint. There is some effect.

Table - Comparison of appearance of painted parts of resin molded products with and without coating layer on searched parts *NBS unit J I S Zj? 00.00 with 730 color difference display. s or less Difficult to visually identify/, 2 to 2.0 Visually identifiable, claim limit 3.0
Easy to visually identify, complaint level

[Brief explanation of drawings]

The drawings illustrate embodiments of the method of the present invention, and FIG. 1 is a longitudinal sectional view of the mold in an open state showing the process of applying a mold release agent, and FIG.
The figure is a vertical cross-sectional view of the concave mold showing the spraying process, Figure 3 is a vertical cross-sectional view of the molding die showing the injection molding process, Figure 7 is a vertical cross-sectional view of the molded product showing the cleaning process, and Figures 5 and 3 are vertical cross-sectional views of the molded product showing the cleaning process. Figure 3 is a vertical cross-sectional view of a molded product showing the undercoating and top-coating processes of the product surface coating process, Figure 7 is a vertical cross-sectional view of a molded product illustrating a conventional example of coating the searched areas, and Figure 2 is a diagram showing each process. FIG. 1...Molding mold, 2-...Concave mold, 6...
・Mold, 4...Cavity, 5...Protrusion, 8...Mold release agent application process, 9...In-mold coat spraying process, 10. ...Injection molding process, 11...Cleaning process, 12...Product surface painting process, 12a...Undercoating process, 12
b...Top coating step, 14...Wax release agent, 15...Coating layer 517...Synthetic resin, 19...Molded product, 21...Surface, 22...Masking tape, 23...
・Primer, 25...Totsubu Coat J&, Factory ~ 餘

Claims (2)

[Claims] (1) Prepare a mold consisting of a mold in which a protrusion is formed on the cavity forming surface and a mold for the mold, and open the mold. , a spraying step for spraying paint onto the protruding portion of the mold; a step of clamping the molding mold and introducing a synthetic resin into the molding mold to mold a molded product; A method for painting a resin molded article having a search section, comprising sequentially performing a product surface coating step of removing the article from a molding die and applying a synthetic resin paint to the surface of the molded article having the search section. (2) The product surface painting process includes a sub-coating process in which a primer is applied after masking the searched areas, and a top-coating process in which a top coat is applied after the masking is removed. A method of painting a resin molded product having the described searching part.