JP2876654B2 - Molding method of resin outer plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of molding a resin component and a steel plate member on separate lines, assembling the resin component to the steel plate member, and painting the same on the same line. The present invention relates to a method for molding a resin outer plate suitable for a resin.

[Prior art] Conventionally, steel plates have been used for outer panels of automobiles, but in order to respond to individualization of users, there is a shift to low-volume production of various types. Molded articles have been adopted, and thermosetting resins reinforced with glass fibers are generally used. As the glass fiber reinforced thermosetting resin, a sheet molding compound (SMC) made by impregnating unsaturated polyester resin with glass fiber is mainly used, but thermoplastic polymers are also used for fenders and engines. It has come to be used in foods and the like.

When this resin part is used for the outer panel, the resin part is assembled on the steel body and the same line is applied in order to make the finished appearance of the surface such as color, texture, gloss etc. with the steel part the same. An on-line painting method for painting is advantageous.

Japanese Patent Application Laid-Open No. 62-4466 discloses that an undercoating film containing conductive fine particles is formed on the outer surface and inner surface of a molded article made of synthetic resin, and the outer surface of the synthetic resin molded article is formed on the outer surface of the synthetic resin molded article together with the vehicle body on a vehicle body painting line. A method of applying a top coat by painting has been proposed.

In order to carry out the online coating method in this way, as shown in FIG. 3, a conductive primer is applied to the surface of a resin-made vehicle body part molded in a separate line in advance to form a conductor. An online coating method is used in which the paint is processed so as not to interfere with the electropainting, and then assembled on a steel plate body and painted on the same line.

In particular, in the case of using SMC, an in-mold coating method (hereinafter referred to as IMC) that can be painted simultaneously with molding and that prevents pinholes generated during molding has recently been developed and put into practical use. Became.

The present applicant has previously filed a patent application (Japanese Patent Application No. 1-181778) regarding the invention of in-mold coating of plastic.
No.).

[Problems to be solved by the invention]

In the plastic in-mold coating method, for example, when resin parts are used for the engine hood 1,
As shown in FIG. 4, since the conductive primer 1b applied to the SMC 1a is applied only to the surface of the SMC, static electricity is charged on the surface of the engine hood 1 and the engine hood 1 in this state is attached to the vehicle body. As shown in FIG. 3, when electrostatic painting is performed online, there is a danger that the solvent in the paint may catch fire and cause a fire.

In order to prevent this, it is necessary to provide a vehicle-side hairs made of a steel plate from the painted portion on the surface of the engine hood. One example is shown in FIG. 5 and FIG.

FIG. 5 is a front view showing the rear surface of the engine hood, and FIG. 6 is an enlarged sectional view of the hinge mounting portion. Hinge mounting brackets 11 are mounted on both sides of a lip 1R formed on the rear surface of the engine hood. In this case, as shown by the broken line in FIG.
The conductive primer 1c is sprayed in advance so that it is electrically connected to the surface of the conductive primer 1b from around the hinge attachment part.
Is painted. As shown in FIG. 6, the hinge fitting 11 is fixed on the conductive primer 1c with an adhesive 12 and a bolt 13, and a hinge 14 is fixed on the hinge with a bolt 15. As shown in FIG. 3, when the engine hood 1 is mounted on a vehicle body made of steel plate, the hinge 14 grounds static electricity charged on the engine hood to the vehicle body.

Elimination of static electricity by the above-described method involves the steps of spraying and drying a conductive primer, and reduces the advantage of the IMC in which the engine hood is molded and painted in the same mold.

The present invention solves the above-mentioned problems, and can perform a grounding measure for a resin part in the same mold at the time of molding, assemble the resin part as-molded on a steel plate body, and enable online painting. It is an object of the present invention to provide a molding method.

[Means and Actions for Solving the Problems] The present invention places a conductive SMC on a part of the periphery of a mold, superimposes a non-conductive SMC thereon, press-molds a resin outer plate, A conductive paint is injected into the surface of the non-conductive SMC with the pressure of the mold released, and then the molding pressure is increased to flow the paint into the mold. And a method for forming a resin outer plate by electrically connecting the resin outer plate formed portion with the conductive SMC.

The resin outer plate molded by this molding method has a surface covered with a conductive paint, and the conductive paint is electrically connected to a molded portion of the resin outer plate made of the conductive SMC on the back surface. When a mounting bracket is attached to the molded part of the resin outer plate made of conductive SMC on the back surface of the resin outer plate and assembled to a steel plate member manufactured on a separate line, static electricity charged on the resin outer plate causes the steel plate member to When the steel plate member and the resin outer plate are painted on-line under the same painting conditions, the paint is prevented from being ignited by static electricity.

〔Example〕

 Embodiments of the present invention will be described with reference to the drawings.

1 and 2 show a case where the present invention is applied to the molding of an engine hood of an automobile. FIG. 2 is a sectional view showing a molding die, and FIG. FIG. 1 (B) is a plan view showing the state, and FIG. 1 (B) shows a cross section taken along line XX of FIG. 1 (A).

A tab 2 serving as a paint inlet is formed in a molded engine hood 1. Engine hood 1 with this tab 2
Is formed between the lower mold 3 and the upper mold 4 of the split mold, a cavity having a shape corresponding to the molded body, and a paint injection port 5 at a position corresponding to the tab 2 in the upper mold 4; On the other side, a lower die 3 is provided, which is connected to a vacuum pump.
The upper mold 4 and the upper mold 4 are provided with a temperature control circuit 7, and a sealing material 8 is provided on the joint surface between the lower mold 3 and the upper mold 4. A pressure sensor 9 is provided. The lower mold 3 is provided with a concave portion 10 for forming a rib on the back surface of the engine hood.

Next, a molding method using the mold shown in FIG. 2 will be described with reference to FIG.

As shown in FIG. 1, a conductive SM having a surface electric resistance of 10 ⁷ to 10 ⁸ Ω is placed in a lower mold 3 of a mold whose temperature is controlled at 140 to 150 ° C.
The C sheet 1B is placed so that a continuous layer is formed in the range from the outer peripheral portion to the hinge mounting portion, and the non-conductive SMC sheet 1A is placed thereon.
Overlaid. The non-conductive SMC sheet 1A has a large charge area in order to reduce the flow of SMC during pressure compression molding.

The above 4 is closed, and a molding pressure of 70 to 80 kg / cm ² is maintained for a specified time. This time is the time for the SMC in the mold to pass through the peak of exothermic expansion and enter the curing shrinkage stage. When the detection value of the pressure sensor 9 reaches a predetermined pressure during the molding of the SMC, a signal is sent to the vacuum deaerator, the pressure of the press is released, and the inside of the mold kept closed without applying the molding pressure is evacuated. Degas. Next, conductive paint is injected at a high pressure of about 300 kg / cm ² from the injection port 5 at the position of the tab 2, and after the paint is injected, the molding pressure is increased to 70 to 80 kg / cm ² again, and the state is maintained for a predetermined time. Hold and cure paint.

The resin used for the "conductive paint" is a resin that can be dried and cured at a temperature lower than the heat resistance of the SMC, has adhesion to the SMC surface, and at the same time, connects the conductive material in a chain to provide conductivity. Any urethane resin (isocyanate compound), polyester urethane resin, acrylic resin and the like are preferable.

The conductivity is adjusted by the type and amount of the conductive agent and the type, amount and film thickness of the pigment used in combination.

When the molding pressure is released and the mold is evacuated while the mold is closed, and the paint is injected, the non-conductive SMC sheet 1A and the conductive SMC sheet 1B in the mold are integrally joined and contracted. As a result, the conductive paint flows well on the cured surface of the SMC, and a good paint can be stably obtained.

In the molded engine hood, the conductive paint on the front surface and the conductive SMC on the hinge mounting portion on the back surface are electrically connected, so when this resin engine hood is mounted on the vehicle body, the charged static electricity is It is grounded to the steel plate body via the hinge, and accidents due to static electricity can be prevented.

The coating process of a steel plate body may be performed by a commonly used method, and after the steel plate surface is subjected to rust removal or rust prevention treatment, the electrodeposition paint is subjected to a pre-treatment such as a conversion coating treatment by zinc phosphate treatment or the like. Paint and bake. Either a cationic electrodeposition paint or an anionic electrodeposition paint can be used as the electrodeposition paint, but a cationic electrodeposition paint is preferable in terms of durability.

Next, an alkyd resin-based or polyester resin-based or acrylic resin-based paint is applied on the electrodeposition paint film, for example, by electrostatic coating, and baked according to a conventional method to form an intermediate coating film.

An alkyd resin, an acrylic resin, a polyester resin, a fluorine-containing resin, or the like is applied as a top coat on the middle coat by the same method as the middle coat.

Intermediate coating and overcoating processes for steel plate members and resin outer panels are carried out on the same line under the same coating conditions without danger of fire, and the coated steel plate members and resin outer panels do not have different colors and uneven color tone. The appearance finish is improved.

〔The invention's effect〕

In the present invention, grounding measures are taken at the time of molding the resin outer plate, so the molded resin outer plate is assembled as it is to a steel plate member, and these are effectively coated on the same line under the same coating conditions without danger of fire occurrence. There is an effect that can be implemented.

[Brief description of the drawings]

1 and 2 show a case where the present invention is applied to the molding of an engine hood of an automobile. FIG. 1 (A) is a plan view showing a state where a mold of SMC material is charged, and FIG. B) is a cross-sectional view of the first (A) taken along line XX, FIG. 2 is a cross-sectional view showing a molding die, FIG.
FIG. 6 to FIG. 6 show the prior art, and FIG.
Is a front view of the surface of the engine hood molded by IMC.
FIG. 5B is a sectional view taken along line YY in FIG.
The figure is a front view showing the back side of the engine hood, and FIG. 6 is an enlarged sectional view of the hinge mounting portion. 1: Engine hood, 2: Paint inlet tab 3: Lower mold, 4: Upper mold 5: Paint inlet, 6: Nipple 7: Temperature control circuit, 8: Seal material 1A: Non-conductive SMC sheet 1B: Conductive SMC sheet

Claims (1)

(57) [Claims] 1. A conductive SMC is placed on a part of the periphery of a mold, a non-conductive SMC is superimposed on the conductive SMC, and a resin outer plate is formed under pressure, and the pressure of the mold is released. A conductive paint is injected into the surface of the non-conductive SMC, and then the molding pressure is increased to flow the paint into a mold, and the paint and the conductive SMC molded portion of the resin outer plate are electrically connected. A method for forming a resin outer plate, characterized by being connected.