JPS60261575A - Partial painting method of plastic molded article - Google Patents

Abstract

PURPOSE:To make the parting line clear by coating a primer on the masked inner peripheral surface, removing the masking, clamping the mold, injecting a resin, masking the part not to be painted, and then overcoating. CONSTITUTION:A masking member is furnished to the inner peripheral surface of a cavity 1, a primer paint 5a is previously mold-coated, and the primer paint is closely adhered to the surface to be painted of a plastic molded article when the plastic is molded. Simultaneously, the end surface of the primer paint at the parting line of the part not to be painted is completely covered with the resin and a paint 5b. Consequently, the primer paint is not exposed at the parting line part, and the resistance of the coated film to solvents is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for partially painting a resin molded article, such as a resin bumper for an automobile.

(Prior art) When coloring only a part of the painted surface of various products such as metal products or resin products, only a part of the painted surface is exposed during the painting process, and other non-painted parts are covered and painted. do.

To perform such partial painting, a so-called spray painting method is used, in which the product is partially covered with a 7-sking table or masking jig, and then the paint is sprayed using a spray gun. As shown in FIG. 12 (A), a heat-resistant and solvent-resistant masking tape 2 is first applied to the non-painted area 1 (area surrounded by broken lines) of the product, for example, the bumper W.

Next, as shown in FIG. 12(B), the primer paint 5a is sprayed over the entire surface of the bumper W using the spray gun 3 to perform primer coating.

The primer coated product is placed in a drying oven at an ambient temperature of about 120° C. for about 10 minutes and baked to dry (depending on the paint, it may be at room temperature) to ensure that the primer paint 5a adheres to the bumper W.

Furthermore, as shown in FIG. 12(C), a top coat 5b is sprayed onto the primer paint 5a using a spray gun 4,
This is dried in a drying oven at a temperature of about 120°C for about 20 minutes to improve the adhesion between the primer paint and the second coat.

Finally, as shown in FIG. 12(D), the masking tape 2 described above is peeled off. If the mass 4-ing day 12 is removed, a bumper W with no paint attached to the non-painted portion 1 will be obtained, as shown in FIG. 12(E).

However, in the bumper W painted by such a painting method, as shown in FIG. There is a problem that the parting line becomes unclear.

(Purpose of the Invention) The present invention has been made by focusing on the above-mentioned problems, and provides a resin molded product that has a clear parting line after painting and can be painted quickly and easily. The purpose of the present invention is to provide a partial painting method.

(Structure of the Invention) In order to achieve the above object, in the present invention, before performing resin molding, a primer paint is applied in advance to the inner peripheral surface of the cavity, and when resin molding is performed, this primer paint is applied to the resin molding. It is characterized in that the surface of the product is mold-coated, and the end surfaces of the primer paint are covered with resin and top coat paint at the parting line portion of the unpainted part.

(Example) Hereinafter, an example of the method of the present invention will be described in detail based on the drawings.

The method of the present invention performs painting using a mold coating process. Mold coating treatment here refers to a method in which paint is applied in advance to the cavity of a mold used to make a resin molded product, and then when resin is injected, the paint adheres to the resin surface.

However, when processing this Moltco-1, the coating process differs slightly depending on the type of resin base material for the resin molded product, so the following explanation uses ordinary polypropylene as the resin base material for convenience. Resin 3 - The case of molding a bumper will be explained. Furthermore, the 12th
The same reference numerals are used for the same members as those shown in Figures (A) to (F).

First, the molding die 10 shown in FIG. 1 (△) is heated to about 70°C
An M-type agent (based on wax as a main component) 11 is applied to the inner circumferential surface 10a of the cavity in a moderately heated state, and this is wiped off. Although the W shape of the mold release agent 11 is somewhat exaggerated in FIG. 1(B), the 1m mold agent 11 is evenly applied in a film over the entire inner peripheral surface 10a of the cavity.

Next, as shown in FIG. 2(A), this cavity inner peripheral surface 1
A masking tape 2 (or a masking jig may be used) having a predetermined meat #11 is attached to a predetermined position of 0a.

Figure 3 (A) shows the primer coating process, in which a spray knife 3 is used to coat a masking tape 2 with a release agent 11 and a primer paint 58 to a uniform thickness. . After applying this primer paint 5a, take a setting time of about 5 minutes and apply the primer paint 58.
The masking tape 2 is removed after the solvent inside has completely evaporated.

Note that this masking tape 2 can be peeled off relatively easily because the mold release agent 11 is interposed between the masking tape 2 and the cavity inner circumferential surface 10a. Furthermore, this masking tape 2 is not subject to thermal deformation and is not affected by the solvent of the top coat, so it can be reused.

Fixed side mold 1 after this masking tape 2 is removed
0, the core side mold 12 is clamped as shown in FIG. The cavity 13 created by this mold clamping does not simply have an inverted U-shaped cross section, but a part of it protrudes by the thickness 12 of the primer paint 5a, and this protruding part 13a is the surface of the primer paint 5a. It is almost on the same level as 14.

FIG. 5 is a schematic cross-sectional view of an injection molding device M, in which resin heated to about 40° C. and made fluid is injected into a cavity 13 of the injection molding device M. This resin 15 solidifies in about 0.5 minutes. This tree 1115 and the primer paint 5a are firmly attached due to the anchor effect, and since the primer paint 5a is in contact with the fixed mold 10 via the mold release agent 11, the resin solidified from within the molds 10, 12 Even when the bumper W is taken out, there is no fear that the primer paint 5a will adhere to the fixed mold 10 and the primer paint 11 will peel off from the resin bumper W.

The resin bumper W taken out from the molds 10 and 12 is coated with primer paint 5 as shown in FIGS.
a surface 14 and the surface 1a of the non-painted part 1 of the resin bumper W
and are almost flush. In other words, since the end surface 6 of the primer paint 5a with poor solvent resistance is covered with the resin 15 which is the base material of the bumper,
At the current stage of applying this coating method, at least as far as this end face 6 is concerned, the situation where the cut line becomes unclear can be prevented.

:1 ''11 fat t:y t<-W'' vs. 6 Figure 7 (A
) 1° Set the masking jig 16 as shown.

This masking jig 16 is slightly smaller than the outer circumference of the non-coated portion 1.

Resin bumper W with this masking jig 16
is installed on the caster 17 as shown in FIG.
B, and the painted surface of this resin bumper W is engraved and top coat paint 5b is sprayed with a spray gun 4. After this top coat, the resin bumper W@atmospheric wetness a is 120℃
A coating film is formed by a conventional method such as placing it in a furnace for about 20 minutes and baking it.

Next, as shown in FIG. 9, the masking jig 16 is removed from the resin bumper W. As described above, this masking jig 16 is slightly smaller than the non-painted area 1, so when this masking jig 16 is removed, the top coat 5b is shown somewhat exaggerated in FIG. As shown in FIG.

This occurs because the peel strength of the top coat 51) satisfies the relationship expressed by the following equation (1). The details of this formula (1) are shown in the table below.

7- Peel strength with primer coated surface (A) N Paint film strength (
B) 〉 Peel strength of primer-unpainted surface (C)...
...(1) That is, as is clear from the above equation (1), the top coat paint 5b adheres to the primer paint 5a quite firmly, but the non-painted portion 8-1 of the resin bumper W Since the degree of adhesion with the masking jig 16 is weak, as the masking jig 16 peels off, the "double paint 5" on the outer periphery of the masking jig 16 is removed.
b will be pulled up and break.

The fact that the top coat 5h protrudes above the non-painted area 1 in this way means that the primer paint 5a is not exposed to the outside at all without removing it. The resin 15 and the top coating 5b prevent the solvent from coming into contact with the primer coating 5a.

Finally, by cutting the protruding top coat 511 using a cutter or the like, a resin bumper W4 with a clear paint parting line as shown in FIG. 11 is obtained! :Obtainable.

In addition to the above-mentioned examples, as the sealing material for the resin bumper, as shown in the table above, paint volip D-pyrene, R-
It can also be covered with IM urethane, etc. In addition, in this example, the masking member was attached (prior to pulling, an orchid type agent was applied to the inner circumferential surface of the cavity, but the inner circumferential surface was coated with Teflon, or a resin with a good cross-section shape was used. It is not necessary in some cases.

(Effects of the Invention) As is clear from the above explanation, according to the method of the present invention, a masking member is attached to the inner circumferential surface of the key bit (JI) (shell primer coating 1 is preliminarily coated with Mold Nico-1). a3
During resin molding, this primer paint was brought into close contact with the painted surface of the resin molded product, and at the parting line part of the non-painted part, the end face of this primer paint was covered with the resin and top coat, so that the parting line part Primer paint is exposed! Since the solvent resistance of the paint film can be improved, the paint separation line, which is extremely important for painting, can be made very clear.

[Brief explanation of the drawing]

Figures 1 and 3 (△) are perspective views of essential parts showing one embodiment of the method of the present invention step by step; Figures 1 to 3 (B) are front 1): (Figures 1 to 3 (△)) 4 is a cross-sectional view showing the mold clamping state of the same example, =1
1- Applicant: Nissan Motor Co., Ltd. Cedar Figure 5 is a cross-sectional schematic diagram of an injection molding device, Figures 6 and 7 (A)
6 and 7 (B) are cross-sectional views taken along the line B-B shown in FIGS. 6 and 7 (Δ), and FIG. The 8th factor is a schematic perspective view showing the top coating process of the same example, Fig. 9 is a perspective view showing the state in which the masking jig of the same example is removed, and Fig. 10 is along the x-X line of Fig. 9. 11 is a sectional view showing a resin bumper in a painted state according to the same embodiment, and FIGS. 12(A) to (E)
) is a perspective view of a main part showing a conventional partial painting method step by step, and FIG. 12(F) is a sectional view showing a bumper in a state where painting is completed by the same method. 1... Non-painted part, 2... Masking tape, 5...
... Paint film, 5a... Primer paint, 5b... Top coat paint, 6... End surface, 10... Cavity side mold,
10a... Cavity inner peripheral surface, 11... Mold release agent, 1
2... Core side mold, 13... Cavity, 15.
...Resin, 16...Masking jig, W...Resin bumper. 12- 13- Kusuda≧1-

Claims (1)

[Claims] A step of attaching a masking member to a part of the inner circumferential surface of the cavity of a molding die, a step of applying a primer coating to the inner circumferential surface of the cavity, and a step of attaching a masking member to a part of the inner circumferential surface of the cavity of the mold, and after removing the masking member, a step of attaching a masking member to a part of the inner circumferential surface of the cavity of the mold. A process of clamping the mold and injecting resin into the cavity, a process of taking out the resin molded product from the mold, and attaching a masking jig to the non-applied area of the painted surface,
a step of applying a top coat to the painted surface and baking it;
A method for partially painting a resin molded product, comprising the step of peeling off the masking jig.