DE4024274C2 - Method for producing a padded polypropylene equipment part, in particular for vehicles - Google Patents

Description

The invention relates to a method for producing a padded polypro pylen equipment part, in particular for vehicles, which has a carrier layer, has a cushion layer and a film-like surface layer. The aim is to make plastic parts increasingly recyclable design. In the case of multi-layer parts, all layers should be the same Chen basic material exist. Because of its excellent recyclability speed should therefore be used for upholstered vehicle equipment, such as In instrument panels, armrests, glove box covers, or the like. Polypropylene are used as plastic.

DE 38 42 846 A1 describes a process for the production of polyolefin Sandwich moldings described, which as a classic particle foam pro process can be called. Here are the foaming process trimmed foam pearls are foamed by applying hot steam. This method is not universally applicable, in particular also not for the production of an at least three-layer molded body after the Preamble of claim 1 of the present extension. For the rest is a sol cher three-layer molded body made of other materials from the DE 38 37 221 A1 known.

At least internal state of the art is the proposal to use a polypropylene Carrier part, which may also contain talc, and a prefabricated poly  propylene particle foam part and a deep-drawn polypropylene surface to connect the foil in the order mentioned. To do this, click on apply appropriate adhesive to both sides of the particle foam part gen. The surface film itself can also be constructed in multiple layers and especially on the outside certain admixtures of EPDM Haptic improvement included.

However, the problem here is the adhesion between the particle foam and the carrier layer or the surface layer, since this particle foam resembles features with the known polystyrene blocks. On the other hand, known polypropylene particle foam shrinkage at higher temperatures on.

The object of the invention is therefore to provide a manufacturing process for a multilayer to show complete, upholstered polypropylene equipment, in which an opti Male connection of the individual layers is made possible. To solve this problem it is provided that a film-like polypropylene Surface layer and a prefabricated polypropylene carrier layer in one Forming tool are inserted and between the film-like polypropylene Surface layer and the prefabricated polypropylene backing layer under Influence of foamable polypropylene material for the cushion layer in Form of granules introduced and then by heating the mold the granulate to form the upholstery layer polypropylene foam is heated to its frothing temperature, during the frothing mens by the molding tool pressure on the upholstery layer polypropylene foam is exercised. Advantageous further training is the subject of the Unteran claims.

It is thus proposed to place the cushion layer directly between the supports layer and the surface layer in a mold, so that optimal contact to the two boundary layers is guaranteed. For one sentence comes for this under the influence of heat foamable polypropylene, wel  the cushion layer of a vehicle made entirely of polypropylene Equipment forms. This polypropylene foam advantageously shows For example, in comparison to polyurethane at half density a better energy sorption, which is particularly important with regard to the risk of injury to vehicle Equipment is essential. In addition, the Upholstery layer in different parts of the equipment from various of such thickness. Advantageously, the Process simply create undercuts. Here are also advantageous no adhesives required.

It is also proposed that the polypropylene material for the cushion layer as granules between the carrier layer and the surface layer bring. This granulate can also be pre-assembled, but still not foamed molded part, which is made of pressed, not yet warm traded granulate is manufactured, be introduced. The foaming pro Process heat is then carried out in a particularly simple manner Heating the mold can be introduced.

Furthermore, it is suggested to achieve particularly good results rend foaming by the mold or by the ent speaking mold halves of the mold adjacent layers (Backing layer or surface layer) pressure on the cushion layer poly to exercise propylene foam. This will cause excessive blistering avoided and also the adhesion between the individual layers improved. The easiest way to apply the pressure you want is through in the two mold halves of the mold during the foaming process to move towards each other.

In this context, it may be advisable to use the film-like poly propylene surface layer by negative pressure or by suction on the  to keep associated mold half of the mold. Here it is too possible to thermoform the PP surface film directly in this mold half.

The attached schematic shows a section through a molding tool, whereby in the left half of the picture the polypropylene material for the upholstery layer before frothing, and in the right half of the picture after frothing is shown.

Shown is a polypropylene equipment part designated in its entirety with 1 , which consists in detail of a carrier layer 2 , a cushion layer 3 , and a film-like surface layer 4 . This piece of equipment is manufactured in a molding tool 5 , which has one of the surface layer 4 associated mold half 5 a, and one of the carrier layer 2 associated mold half 5 b.

First, in the mold 5 on the mold half 5 b a carrier layer 2 forming the carrier part is inserted, which was previously made of polypropylene in an injection molding process. On the mold half 5 a, a polypropylene film is placed and held there by suction. This polypropylene film, which forms the surface layer 4 , can be preformed or molded over the mold half 5 a.

The polypropylene material for the cushion layer 3 is then introduced into the mold 5 between the two layers 2 , 4 . As the left half of the picture shows, the foamable polypropylene material only partially fills the free volume. Then the polypropylene material is heated to its foaming temperature by heating the mold 5 , at the same time the mold half 5 a being moved slightly in the direction of the mold half 5 b to exert pressure on the polypropylene foam of the cushion layer 3 . The right half of the picture shows the condition after foaming.

Claims (4)

1. A method for producing a padded polypropylene equipment part ( 1 ), in particular for vehicles, which has a carrier layer ( 2 ), a cushion layer ( 3 ) and a film-like surface layer ( 4 ), characterized in that a film-like polypropylene surface layer ( 4 ) and a prefabricated polypropylene carrier layer ( 2 ) are introduced into a mold ( 5 ) and between the film-like polypropylene surface layer ( 4 ) and the prefabricated polypropylene carrier layer ( 2 ) a polypropylene material for the cushion layer ( 3 ) introduced in the form of granules and then, by heating the molding tool ( 5 ), the granules to form the cushion layer polypropylene foam are heated to their foaming temperature, pressure being exerted on the cushion layer polypropylene foam by the molding tool ( 5 ) during foaming. 2. The method according to claim 1, characterized in that the film-like polypropylene surface layer ( 4 ) is held by negative pressure on the associated mold half ( 5 a) of the mold ( 5 ). 3. The method according to claim 2, characterized in that the surface polypropylene film in the mold half ( 5 a) of the mold ( 5 ) is formed. 4. The method according to any one of the preceding claims, characterized in that a Po lypropylene injection molded part is used as the carrier part (carrier layer 2 ).