DE4116437C2 - Process for the production of a molded plastic part - Google Patents

Abstract

For ease of handling and multiple uses, a method for producing a plastic molded part by using the following process steps is proposed: DOLLAR A (a) a transparent film (1) completely coated with a colored lacquer (5) is introduced into a mold (7) in such a way that that they thermoformed the colored lacquer layer (5) on their side facing away from the molding tool (7) and then in the open molding tool (7) in a vacuum process; DOLLAR A (b) the mold (7) is closed by means of a core tool (10) assigned to it, the core tool (10) being dimensioned such that between its inner surface (11) and the lacquered surface in the mold (7) Film (1, 5) a defined space (12) remains accessible via at least one channel (13); DOLLAR A (c) the intermediate space (12) is filled via the channel (13) with a hardenable plastic material (14) which connects over the entire surface to the side of the film (1, 5) coated with the colored lacquer (5); and DOLLAR A (d) after the hardening of the plastic material (14) the molded part (15) is removed.

Description

The invention relates to a method for producing a molded plastic part and a Molded part produced by this process and its use.

It is known to produce molded plastic parts by injection molding. of such Manufactured molded parts are also used in the automotive industry, for example as a cover for Bumper or used as a mirror housing. There is often a desire to optical enhancement of the vehicle such, used just outside Adapt molded parts to the vehicle exterior color. For this purpose, the molded parts in known way, sometimes in body color, painted. This process is not only very elaborate, it also creates difficulties to apply the paint permanently to the molding to apply without it again after a relatively short time, favored by Rockfalls and weather influences, peels off.

An injection molding process is known from EP 0 101 095 A2, in which during the Molding process a decorative pattern on the surface of the molded part to be produced is applied. In a transfer technique according to a first variant of the Process a carrier film, which carries the pattern to be transferred, in a tool deep-drawn, the tool closed with a core tool and the film with a Plastic melt injected back, the pattern with the hardening plastic combines. In an alternative embodiment, the film is on top of the pattern injection molded on the opposite side, so that the film with the injected plastic combines.

Other processes are aimed at the production of upholstered plastic molded parts. So that's it DE 21 14 181 A is a process for producing upholstered trim parts known for vehicle interiors, in which a cushion insert in a mold inserted and then with a solidifying, forming the support layer Plastic compound is injected. DE 21 26 587 A is a process for the production a multi-layered object with a foam base, after which a foamable plastic in a molding tool against one Foam or other wrapping material is foamed. DE 17 79 871 A  finally describes a process for producing foamed moldings Use as a cushion for dashboards, seat cushions and armrests. For that first the surface of a mold with a clear one Coated polyurethane layer. Then a second coat of paint is applied sprayed onto the polyurethane layer. Then a third spray coating, also a Polyurethane foam applied, which is subsequently obtained with the molding is foamed. These processes aim at the production of matt, textured and soft surfaces of the fittings and are not used to produce hard plastic Molded parts with lacquered, highly smooth surfaces, for example, suitable for vehicle exterior parts.

The invention is therefore based on the object of a method for producing To develop molded plastic parts with a high surface quality that is easy to handle is and gives the molded part permanent protection. According to the invention Task by those mentioned in claim 1 Process steps solved.

The vacuum expediently remains on even after the deep-drawing process Slide on. It remains fixed in its position, what for the subsequent work step, namely filling the space with plastic material is advantageous. So can For example, wrinkles can be prevented.

The demolding of the molded part, i.e. the removal of the finished workpiece from the Tool, is carried out according to a further embodiment of the invention in that in the Channels that were used to create the vacuum are now blown with compressed air. Consequently special ejectors, as are known and customary in injection molding machines, omitted.

The further subclaims contain further expedient configurations of the Invention.

An embodiment of the invention will become more apparent from the drawing below explained. It shows the production of a colored plastic molded part, which as Part of a motor vehicle bumper is attached to a carrier plate and in primarily to visually upgrade the bumper and thus the vehicle. The Plastic molded part thus represents an aperture or cover, the color of the Body color is adjusted.  

So far, the cover has been painted in the usual way. Apart from the fact that the Paint layer of the exposed parts of the vehicle for damage existing bumper is very quickly affected, there are often already at Difficulty applying the paint, especially when using a Metallic effect paint, which is known to contain the smallest aluminum flakes. If those Aluminum plates not parallel to each other and also not parallel to the painted one Surface are aligned, which is regularly the case in such areas of the surface is in which - due to small radii or sharp edges, pronounced There are transitions from one surface part to another, then streaks occur in the paintwork, which reduce the visual impression. These problems occur the cover made according to the invention not on.

The drawing shows in detail:

Fig. 1, the one-sided coating of a deep-drawable film with a metallic effect paint,

Fig. 2 u. 3 deep-drawing the painted film in the open first half of an injection mold,

Fig. 4, the injection mold closed by means of the second half and

Fig. 5 in an enlarged view the film trimming on the demolded cover.

First of all, a thermoformable, transparent and weather-resistant film 1 is coated on one side with a metal spray paint 3 using a suitable spray device 2 . For this purpose, the film 1 is guided in the direction of arrow 4 under the stationary spray device 2 , so that a uniform layer of lacquer 5 is formed. The lacquer layer 5 can then flash off by means of a downstream suction fan in a fume cupboard 6 .

Thereafter, the lacquered film 1 , 5 is heated to the deep-drawing temperature and deep-drawn in a deep-drawing tool 7 in a vacuum process, with the non-lacquered film side 8 coming into contact with the mold wall 9 of the deep-drawing tool 7 . Half of an injection mold, which is also referred to as the die side, serves as the deep-drawing tool 7 . FIG. 2 shows the coated film 1 , 5 and the deep-drawing tool 7 before deep-drawing, FIG. 3 afterwards.

The lacquered film 1 , 5 now remains in the mold half 7 according to FIG. 3, and the injection mold is closed with its other half, the core side 10 , as shown in FIG. 4. This leaves a cavity 12 between the lacquer layer 5 and the end face 11 of the core side 10 , into which a plasticized thermoplastic material is now injected via a channel 13 , which adheres firmly to the lacquered film 1 , 5 after cooling without additives such as glue. The cooled thermoplastic material forms, as it were, a support shell 14 for the lacquered film 1 , 5 , but at the same time also protects the lacquer layer 5 .

After a certain cooling time, the injection mold is opened, that is to say the two halves 7 and 10 are separated from one another, and the three-layer but one-piece molded part 15 , which comprises the lacquered film 1 , 5 and the support shell 14 , is removed.

In a further operation, as indicated in FIG. 5, the protruding edge 16 of the lacquered film 1 , 5 is cut off.

The finished molding 15 can then be used to complete the bumper, not shown in the drawing. The film 5 is largely protected by the film 1 on the front and the back-injected layer 14 made of thermoplastic material. The metallic effect is fully have and without visual impairments to advantage, since the ahead of the deep-drawing process within the coating layer 5 in several planes parallel to each other aligned aluminum platelets have been indeed stretched by the deep-drawing process in a certain way, but not lost their parallelism to the surface of the molded part ,

Claims (8)

1. Process for the production of a plastic molded part with the process steps

• a) a film ( 1 ) coated with a colored lacquer ( 5 ) is deep-drawn in an open mold ( 7 ) in a vacuum process;
• b) the mold (7) by means of an associated core die (10) closed it, wherein the core die (10) is dimensioned in such a way that between its inner surface (11) and the adjacent in the mold (7) coated film (1 , 5 ) a defined space ( 12 ) remains accessible via at least one channel ( 13 );
• c) the intermediate space ( 12 ) is filled via the channel ( 13 ) with a hardenable plastic material ( 14 ) which connects over the entire surface with the lacquered film ( 1 , 5 );
• d) after the hardening of the plastic material ( 14 ), the molded part ( 15 ) is removed,

characterized in that a transparent film is used as the film ( 1 ) and that this is introduced into the core tool ( 10 ) in such a way that it completely covers the colored lacquer on its side facing the inner surface ( 11 ) of the core tool ( 10 ) and that the side of the film ( 1 ) coated with the colored lacquer ( 5 ) is connected to the entire surface of the hardenable plastic material ( 14 ). 2. The method according to claim 1, characterized in that a metallic effect lacquer is used as the lacquer ( 5 ). 3. The method according to claim 1 or 2, characterized in that the film ( 1 ) is coated evenly with the lacquer ( 5 ). 4. The method according to any one of the preceding claims, characterized in that the vacuum between the film ( 1 ) and mold ( 7 ) is maintained at least until after the filling of the space ( 12 ) with the plastic material ( 14 ). 5. The method according to any one of the preceding claims, characterized in that the demolding of the molded part ( 15 ) is carried out by introducing compressed air into the same channels in the mold ( 7 ) that were previously used to generate the vacuum. 6. Use of a molded plastic part ( 15 ) produced by a method according to one of claims 1 to 5 as a cover or cover for a motor vehicle with a paint layer ( 5 ) adapted to the vehicle color. 7. Use according to claim 6, characterized in that the plastic molded part ( 15 ) is designed as part of a motor vehicle bumper. 8. Plastic molded part ( 15 ) which is produced by a method according to one of claims 1 to 5 and is designed as a panel or cover for a motor vehicle and is produced by the following method:
a transparent film ( 1 ) is coated over its entire area with a colored lacquer ( 5 ) and then deep-drawn in an open mold in a vacuum process, the side of the film ( 1 ) coated with lacquer ( 5 ) forming the concave side;
After the mold has been closed, the lacquered deep-drawn film ( 1 , 5 ) is back-injected with a hardenable plastic material ( 14 ) between the core tool and the side of the film ( 1 , 5 ) provided with the lacquer layer ( 5 ), a firmly adhering composite with the structure plastic material ( 14 ) lacquer layer ( 5 ) film ( 1 ) is formed;
wherein the molded plastic part ( 15 ) is adapted to the vehicle color of the motor vehicle by the lacquer layer ( 5 ) lying between the plastic material ( 14 ) and the transparent film ( 1 ).